MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'FEMS Microbiology Reviews' source. Thu, 09 Feb 2012 21:34:59 +0100 http://www.medworm.com/index.php?rid=5674647&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2012.00331.x AbstractTuberculosis (TB) remains a major health threat, killing near to 2 million individuals around this globe, annually. The sole vaccine developed almost a century ago, provides limited protection only during childhood. After decades without the introduction of new antibiotics, several candidates are currently undergoing clinical investigation. Curing TB requires prolonged combination chemotherapy with several drugs. Moreover, monitoring the success of therapy is questionable due to the lack of reliable biomarkers. To substantially improve the situation, a detailed understanding of the crosstalk between human host and the pathogen Mycobacterium tuberculosis (Mtb) is vital. Principally, Mtb's enormous success is based on three capacities: First, reprogramming of macrophages after primar... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5674647 Fri, 10 Feb 2012 01:54:35 +0100 5674647 http://www.medworm.com/index.php?rid=5674648&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2012.00330.x AbstractMeasles remains one of the most important causes of child morbidity and mortality worldwide with the greatest burden in the youngest children. Most acute measles deaths are due to secondary infections that result from a poorly understood measles‐induced suppression of immune responses. Young children are also vulnerable to late development of subacute sclerosing panencephalitis, a progressive, uniformly fatal neurologic disease caused by persistent measles virus (MeV) infection. During acute infection, the rash marks the appearance of the adaptive immune response and CD8+ T cell‐mediated clearance of infectious virus. However, after clearance of infectious virus, MeV RNA persists and can be detected in blood, respiratory secretions, urine and lymphoid tissue for many weeks to m... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5674648 Wed, 08 Feb 2012 05:00:00 +0100 5674648 http://www.medworm.com/index.php?rid=5674649&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2012.00324.x AbstractBartonella spp. are facultative intracellular bacteria that typically cause a long‐lasting intraerythrocytic bacteremia in their mammalian reservoir hosts, thereby favoring transmission by blood‐sucking arthropods. In most cases, natural reservoir host infections are subclinical and the relapsing intraerythrocytic bacteremia may last weeks, months, or even years. In this review, we will follow the infection cycle of Bartonella spp. in a reservoir host, which typically starts with an intradermal inoculation of bacteria that are superficially scratched into the skin from arthropod feces and terminates with the pathogen exit by the blood‐sucking arthropod. The current knowledge of bacterial countermeasures against mammalian immune response will be presented for each critical ste... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5674649 Mon, 09 Jan 2012 05:00:00 +0100 5674649 http://www.medworm.com/index.php?rid=5577112&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2012.00324.x AbstractBartonella spp. are facultative intracellular bacteria that typically cause a long‐lasting intraerythrocytic bacteremia in their mammalian reservoir hosts, thereby favoring transmission by blood‐sucking arthropods. In most cases, natural reservoir host infections are subclinical and the relapsing intraerythrocytic bacteremia may last weeks, months or even years. In this review, we will follow the infection cycle of Bartonella spp. in a reservoir host, which typically starts with an intradermal inoculation of bacteria that are superficially scratched into the skin from arthropod feces and terminates with the pathogen exit by the blood‐sucking arthropod. The current knowledge of bacterial countermeasures against mammalian immune response will be presented for each critical step... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5577112 Mon, 09 Jan 2012 05:00:00 +0100 5577112 http://www.medworm.com/index.php?rid=5625233&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2012.00328.x AbstractMulti‐species biofilm communities are environments in which complex but ill understood exchanges between bacteria occur. Although monospecies cultures are still widely used in the laboratory, new approaches have been undertaken to study interspecies interactions within mixed communities. This review describes our current understanding of competitive relationships involving non‐biocidal biosurfactants, enzymes and metabolites produced by bacteria and other microorganisms. These molecules target all steps of biofilm formation, ranging from inhibition of initial adhesion to matrix degradation, jamming of cell‐cell communications and induction of biofilm dispersion. This review presents available data on non‐biocidal molecules and provides a new perspective on competitive inter... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5625233 Sun, 01 Jan 2012 05:00:00 +0100 5625233 http://www.medworm.com/index.php?rid=5604502&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2012.00327.x AbstractGram negative bacteria assemble many proteins into the inner and outer membranes, and export a large number of proteins to the periplasm or to the extracellular medium. During the billions of years bacteria have been around, they have evolved a number of different pathways with sophisticated machines to accurately and efficiently move proteins from one location to another. In this review, we first introduce specific proteins that are representative substrates of the protein transport pathways and describe their function. Then their specific routes from synthesis to their destinations are described mentioning the signal peptide that may initiate their export and discuss what is known about the folding state of the substrates during transport. The membrane translocation device involv... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5604502 Sun, 01 Jan 2012 05:00:00 +0100 5604502 http://www.medworm.com/index.php?rid=5594020&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2012.00326.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5594020 Sun, 01 Jan 2012 05:00:00 +0100 5594020 http://www.medworm.com/index.php?rid=5577111&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2012.00325.x AbstractOur knowledge regarding the nature and development of microbial biofilms has grown significantly since the first report of these communities by Antonie van Leeuwenhoek in the late 1600s. Nevertheless, most biofilm studies examine mono‐species cultures whereas nearly all biofilm communities in nature comprise a variety of microorganisms. The species that constitute a mixed biofilm and the interactions between these microorganisms critically influence the development and shape of the community. In this review we focus on interactions occurring within a multi‐species biofilm and their effects on the nature of the mixed community. In general, inter‐species interactions involve communication, typically via quorum sensing, and metabolic cooperation or competition. Interactions amon... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5577111 Sun, 01 Jan 2012 05:00:00 +0100 5577111 http://www.medworm.com/index.php?rid=5550278&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00323.x AbstractLactic acid bacteria are indigenous to food‐related habitats as well as associated with the mucosal surfaces of animals. The lactic acid bacteria family Streptococcaceae consists of the genera Lactococcus and Streptococcus. Members of the family include the industrially important species Lactococcus lactis which has a long history safe use in the fermentative food industry as well as the disease‐causing streptococci S. pneumoniae and S. pyogenes. The central metabolic pathways of the Streptococcaceae family have been extensively studied because of their relevance in the industrial use of some species, as well as their influence on virulence of others. Recent developments in high throughput proteomic and DNA‐microarray techniques, in in vivo NMR studies and importantly, in who... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5550278 Thu, 29 Dec 2011 22:06:56 +0100 5550278 http://www.medworm.com/index.php?rid=5644291&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00323.x AbstractLactic acid bacteria (LAB) are indigenous to food‐related habitats as well as associated with the mucosal surfaces of animals. The LAB family Streptococcaceae consists of the genera Lactococcus and Streptococcus. Members of the family include the industrially important species Lactococcus lactis, which has a long history safe use in the fermentative food industry, and the disease‐causing streptococci Streptococcus pneumoniae and Streptococcus pyogenes. The central metabolic pathways of the Streptococcaceae family have been extensively studied because of their relevance in the industrial use of some species, as well as their influence on virulence of others. Recent developments in high‐throughput proteomic and DNA‐microarray techniques, in in vivo NMR studies, and importantl... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5644291 Wed, 28 Dec 2011 05:00:00 +0100 5644291 http://www.medworm.com/index.php?rid=5550279&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00322.x Discussions will center on structure‐function relationships, regulation, and the role of individual matrix molecules in niche biology. (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5550279 Wed, 28 Dec 2011 05:00:00 +0100 5550279 http://www.medworm.com/index.php?rid=5542482&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00321.x AbstractPathogenic microorganisms employ numerous molecular strategies in order to delay or circumvent recognition by the immune system of their host. One of the most widely used strategies of immune evasion is antigenic variation, in which immunogenic molecules expressed on the surface of a microorganism are continuously modified. As a consequence, the host is forced to constantly adapt its humoral immune response against this pathogen. An antigenic change thus provides the microorganism with an opportunity to persist and/or replicate within the host (population) for an extended period of time or to effectively infect a previously infected host. In most cases, antigenic variation is caused by genetic processes that lead to modification of the amino acid sequence of a particular antigen or... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5542482 Mon, 26 Dec 2011 14:19:48 +0100 5542482 http://www.medworm.com/index.php?rid=5501730&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00320.x AbstractHerpes simplex virus type 1 (HSV‐1) is a neurotropic herpesvirus that establishes latency within sensory neurones. Following primary infection the virus replicates productively within mucosal epithelial cells and enters sensory neurones via nerve termini. The virus is then transported to neuronal cell bodies where latency can be established. Periodically the virus can reactivate to resume its normal lytic cycle gene expression programme and result in the generation of new virus progeny that are transported axonally back to the periphery. The ability to establish lifelong latency within the host and to periodically reactivate to facilitate dissemination is central to the survival strategy of this virus. Although incompletely understood this review will focus on the mechanisms invo... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5501730 Wed, 14 Dec 2011 16:02:26 +0100 5501730 http://www.medworm.com/index.php?rid=5418530&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00315.x AbstractMagnetotactic bacteria are remarkable organisms with the ability to exploit the earth's magnetic field for navigational purposes. To do this, they build specialized compartments called magnetosomes that consist of a lipid membrane and a crystalline magnetic mineral. These organisms have the potential to serve as models for the study of compartmentalization as well as biomineralization in bacteria. Additionally, they offer the opportunity to design applications that take advantage of the particular properties of magnetosomes. In recent years, a sustained effort to identify the molecular basis of this process has resulted in a clearer understanding of the magnetosome formation and biomineralization. Here, I present an overview of magnetotactic bacteria and explore the possible molecu... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5418530 Thu, 17 Nov 2011 05:00:00 +0100 5418530 http://www.medworm.com/index.php?rid=5418529&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00316.x AbstractCytoskeletal proteins are important mediators of cellular organization in both eukaryotes and bacteria. In the past, cytoskeletal studies have largely focused on three major cytoskeletal families, namely the eukaryotic actin, tubulin, and intermediate filament proteins and their bacterial homologs MreB, FtsZ, and crescentin. However, mounting evidence suggests that these proteins represent only the tip of the iceberg, as the cellular cytoskeletal network is far more complex. In bacteria, each of MreB, FtsZ, and crescentin represent only one member of large families of diverse homologs. There are also newly‐identified bacterial cytoskeletal proteins with no eukaryotic homologs, such as WACA proteins and bactofilins. Furthermore, there are universally conserved proteins such as the... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5418529 Thu, 17 Nov 2011 05:00:00 +0100 5418529 http://www.medworm.com/index.php?rid=5397508&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00313.x AbstractStreptomyces bacteria are ubiquitous in soil, conferring the characteristic earthy smell, and they have an important ecological role in the turnover of organic material. More recently, a new picture has begun to emerge in which streptomycetes are not in all cases simply free‐living soil bacteria but have also evolved to live in symbiosis with plants, fungi and animals. Furthermore, much of the chemical diversity of secondary metabolites produced by Streptomyces species has most likely evolved as a direct result of their interactions with other organisms. Here we review what is currently known about the role of streptomycetes as symbionts, with fungi, plants and animals. These interactions can be parasitic, as is the case for scab‐causing streptomycetes, which infect plants, and... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5397508 Tue, 08 Nov 2011 05:00:00 +0100 5397508 http://www.medworm.com/index.php?rid=5550280&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00312.x AbstractThe analysis of different multi‐host systems suggests that even hosts that are not capable of transmitting Borrelia burgdorferi sensu lato (s.l.) to the tick vector, Ixodes ricinus, or that are secondary reservoirs for these agents contribute to the intensity of transmission and to the overall risk of Lyme borreliosis, through the process of vector augmentation and pathogen amplification. On the other hand, above certain threshold densities, or in the presence of competition with primary reservoir hosts or low attachment rate of ticks to reservoir hosts, incompetent or less competent hosts may reduce transmission through dilution. The transmission of B. burgdorferi s.l. is affected by molecular processes at the tick‐host interface including mechanisms for the protection of spi... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5550280 Tue, 01 Nov 2011 04:00:00 +0100 5550280 http://www.medworm.com/index.php?rid=5483922&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00319.x AbstractEffective innate and adaptive immune responses are essential for the control of hepatitis C virus (HCV) infection. Indeed, elimination of HCV during acute infection correlates with an early induction of innate and a delayed induction of adaptive immune responses. However, in the majority of acutely HCV infected individuals these responses are insufficient to clear the virus and persistence develops. In recent years, different mechanisms responsible for the failure of innate and adaptive immune responses have been identified. These include the proteolytic cleavage of molecules playing key roles in the induction of the interferon response, manipulation of interferon‐induced effector proteins, interference with CD8+ T cell function or immune escape in T‐ and B‐cell epitopes. In ... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5483922 Tue, 01 Nov 2011 04:00:00 +0100 5483922 http://www.medworm.com/index.php?rid=5465765&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00318.x AbstractThe microsporidia are a diverse phylum of obligate intracellular parasites related to the Fungi which cause significant and sometimes life‐threatening disease in immune compromised hosts, such as AIDS and organ transplant patients. More recently, their role in causing pathology in immune competent populations has also been appreciated. Interestingly, in several instances the microsporidia have been shown to persist in their hosts long term, causing at opposite ends of the spectrum either an intractable chronic diarrhea and wasting in advanced stage AIDS patients, or asymptomatic shedding of spores in healthy populations. Much remains to be studied regarding the immune response to these pathogens, but it seems clear that CD8+ T cells are essential in clearing infection. However, i... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5465765 Tue, 01 Nov 2011 04:00:00 +0100 5465765 http://www.medworm.com/index.php?rid=5418528&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00317.x AbstractStreptomyces coelicolor is the genetically best characterized species of a populous genus belonging to the Gram‐positive Actinobacteria. Streptomycetes are filamentous soil organisms, well known for the production of a plethora of biologically active secondary metabolic compounds. The Streptomyces developmental life cycle is uniquely complex, and involves coordinated multicellular development with both physiological and morphological differentiation of several cell types, culminating in production of secondary metabolites and dispersal of mature spores. This review presents a current appreciation of the signaling mechanisms used to orchestrate the decision to undergo morphological differentiation, and the regulators and regulatory networks that direct the intriguing development o... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5418528 Tue, 01 Nov 2011 04:00:00 +0100 5418528 http://www.medworm.com/index.php?rid=5397507&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00314.x AbstractProtein phosphorylation on serine, threonine and tyrosine is recognized as a major tool of signal transduction in bacteria. However, progress in the field has been hampered by the lack of global and site‐specific data on bacterial phosphoproteomes. Recent advances in mass spectrometry‐based proteomics have encouraged bacteriologists to start using powerful gel‐free approaches for global detection of phosphorylated proteins. These studies have generated large datasets of proteins phosphorylated on serine, threonine and tyrosine, with identified phosphorylation sites which represent an excellent starting point for in‐depth physiological characterization of kinases and their substrates. The list of phosphorylated proteins inspired a number of physiological studies in which the... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5397507 Tue, 01 Nov 2011 04:00:00 +0100 5397507 http://www.medworm.com/index.php?rid=5376522&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00312.x AbstractThe analysis of different multi‐host systems suggests that even hosts that are not capable of transmitting Borrelia burgdorferi sensu lato (sl) to the tick vector, Ixodes ricinus, or that are secondary reservoirs for these agents contribute to the intensity of transmission and to the overall risk of Lyme borreliosis, through the process of vector augmentation and pathogen amplification. On the other hand, above certain threshold densities, or in the presence of competition with primary reservoir hosts or low attachment rate of ticks to reservoir hosts, incompetent or less competent hosts may reduce transmission through dilution. The transmission of B. burgdorferi sl is affected by molecular processes at the tick‐host interface including mechanisms for the protection of spiroche... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5376522 Tue, 01 Nov 2011 04:00:00 +0100 5376522 http://www.medworm.com/index.php?rid=5331365&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00311.x AbstractStaphylococcal food poisoning is one of the most common food‐borne diseases and results from the ingestion of staphylococcal enterotoxins preformed in food by enterotoxigenic strains of Staphylococcus aureus. To date, more than 20 staphylococcal enterotoxins have been described: SEA to SElV. All of them have superantigenic activity whereas half of them have been proved to be emetic, representing a potential hazard for consumers. This review, divided into four parts, will focus on i) the worldwide story of staphylococcal food poisoning outbreaks, ii) the characteristics and behaviour of S. aureus in food environment, iii) the toxinogenic conditions and characteristics of staphylococcal enterotoxins, and iv) staphylococcal food poisoning outbreaks including symptomatology, occurren... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5331365 Thu, 20 Oct 2011 06:29:18 +0100 5331365 http://www.medworm.com/index.php?rid=5397509&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00311.x AbstractStaphylococcal food poisoning (SFP) is one of the most common food‐borne diseases and results from the ingestion of staphylococcal enterotoxins (SEs) preformed in food by enterotoxigenic strains of Staphylococcus aureus. To date, more than 20 SEs have been described: SEA to SElV. All of them have superantigenic activity whereas half of them have been proved to be emetic, representing a potential hazard for consumers. This review, divided into four parts, will focus on the following: (1) the worldwide story of SFP outbreaks, (2) the characteristics and behaviour of S. aureus in food environment, (3) the toxinogenic conditions and characteristics of SEs, and (4) SFP outbreaks including symptomatology, occurrence in the European Union and currently available methods used to charact... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5397509 Wed, 19 Oct 2011 04:00:00 +0100 5397509 http://www.medworm.com/index.php?rid=5311519&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00310.x AbstractThe Gram‐positive bacterium Bacillus subtilis can initiate the process of sporulation under conditions of nutrient limitation. Here, we review some of the last five years of work in this area, with a particular focus on the decision to initiate sporulation, DNA translocation, cell‐cell communication, protein localization and spore morphogenesis. The progress we describe has implications not just for the study of sporulation but also for other biological systems where homologs of sporulation‐specific proteins are involved in vegetative growth. (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5311519 Thu, 13 Oct 2011 15:56:53 +0100 5311519 http://www.medworm.com/index.php?rid=5294033&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00309.x AbstractCaulobacter crescentus uses a multi‐layered system of oscillating regulators to program different developmental fates into each daughter cell at division. This is achieved by superimposing gene expression, subcellular localization, phosphorylation and regulated proteolysis to form a complex regulatory network that integrates chromosome replication, segregation, polar differentiation, and cytokinesis. In this review, we outline the current state of research in the field of Caulobacter development, emphasizing new findings that elaborate how the developmental program is modulated by factors such as the environment or the metabolic state of the cell. (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5294033 Fri, 07 Oct 2011 23:49:15 +0100 5294033 http://www.medworm.com/index.php?rid=5234247&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00306.x AbstractNumerous viruses of human or animal origin can spread in the environment and infect people via water and food, mostly through ingestion and occasionally through skin contact. These viruses are released into the environment by various routes including water run‐offs and aerosols. Furthermore, zoonotic viruses may infect humans exposed to contaminated surface waters. Foodstuffs of animal origin can be contaminated and their consumption may cause human infection if the viruses are not inactivated during food processing. Molecular epidemiology and surveillance of environmental samples are necessary to elucidate the public health hazards associated with exposure to environmental viruses. Whereas monitoring of viral nucleic acids by PCR methods is relatively straightforward and well‐... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5234247 Fri, 16 Sep 2011 04:00:00 +0100 5234247 http://www.medworm.com/index.php?rid=5234246&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00307.x AbstractIn bird flocks, fish schools and many other living organisms, regrouping among individuals of the same kin is frequently an advantageous strategy to survive, forage and face predators. However, these behaviors are costly because the community must develop regulatory mechanisms to coordinate and adapt its response to rapid environmental changes. In principle, these regulatory mechanisms, involving communication between individuals, may also apply to cellular systems which must respond collectively during multicellular development. Dissecting the mechanisms at work requires amenable experimental systems, for example developing bacteria. Myxococcus xanthus, a Gram negative δ‐proteobacterium, is able to coordinate its motility in space and time to swarm, predate and grow millimeter�... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5234246 Fri, 16 Sep 2011 04:00:00 +0100 5234246 http://www.medworm.com/index.php?rid=5269729&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00304.x AbstractBacteria, fungi, algae and higher plants are the most prolific producers of natural products (secondary metabolites). Compared to macroalgae, considerably fewer natural products have been isolated from microalgae, which offer the possibility of obtaining sufficient and well‐defined biological material from laboratory cultures. Interest in microalgae is reinforced by large‐scale data sets from genome sequencing projects and the development of genetic tools such as transformation protocols. This review highlights what is currently known about the biosynthesis and biological role of natural products in microalgae, with examples from isoprenoids, complex polyketides, nonribosomal peptides, polyunsaturated fatty acids and oxylipins, alkaloids, and aromatic secondary metabolites. In ... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5269729 Mon, 12 Sep 2011 04:00:00 +0100 5269729 http://www.medworm.com/index.php?rid=5218220&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00305.x AbstractToxoplasma gondii is an obligate intracellular protozoan parasite that causes opportunistic disease, particularly in immunocompromised individuals. Central to its transmission and pathogenesis is the ability of the proliferative stage (tachyzoite) to convert into latent tissue cysts (bradyzoites). Encystment allows Toxoplasma to persist in the host, and affords the parasite a unique opportunity to spread to new hosts without proceeding through its sexual stage, which is restricted to felids. Bradyzoite tissue cysts can cause reactivated toxoplasmosis if host immunity becomes impaired. A greater understanding of the molecular mechanisms orchestrating bradyzoite development is needed to better manage the disease. Here we will review key studies that have contributed to our knowledge ... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5218220 Mon, 12 Sep 2011 04:00:00 +0100 5218220 http://www.medworm.com/index.php?rid=5234245&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00308.x AbstractMajor insights into sexual development and cryptic sexuality within filamentous fungi have been gained from investigations using Aspergillus species. Here, an overview is first given into sexual morphogenesis in the aspergilli, describing different types of sexual structures formed and how their production is influenced by a variety of environmental and nutritional factors. It is argued that the formation of cleistothecia and accessory tissues, such as Hülle cells and sclerotia, should be viewed as two independent but co‐ordinated developmental pathways. Next, a comprehensive survey of over 75 genes associated with sexual reproduction in the aspergilli is presented, including genes relating to mating and the development of cleistothecia, sclerotia and ascospores. Most of these g... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5234245 Thu, 01 Sep 2011 04:00:00 +0100 5234245 http://www.medworm.com/index.php?rid=5218219&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00304.x AbstractBacteria, fungi, algae and higher plants are the most prolific producers of natural products (secondary metabolites). Compared to macroalgae, considerably fewer natural products have been isolated from microalgae, which offer the possibility of obtaining sufficient and well‐defined biological material from laboratory cultures. Interest in microalgae is reinforced by large‐scale datasets from genome sequencing projects and the development of genetic tools such as transformation protocols. This review highlights what is currently known about the biosynthesis and biological role of natural products in microalgae, with examples from isoprenoids, complex polyketides, non‐ribosomal peptides, polyunsaturated fatty acids and oxylipins, alkaloids, and aromatic secondary metabolites. I... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5218219 Thu, 01 Sep 2011 04:00:00 +0100 5218219 http://www.medworm.com/index.php?rid=5194824&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00303.x AbstractInvestigating the contribution of microbial populations to biochemical processes of global significance is challenging as there are few approaches that can detect microbial metabolic activities on single cell level. Given the widespread distribution and importance of microorganisms in elemental transformations, improved methods for measuring microbial activities in naturally‐occurring microbial communities is essential. In the present article, microautoradiography (MAR), Raman microspectroscopy and secondary ion mass spectrometry (SIMS) and their combination with isotope labeling and molecular genetic methods for cell identification (i.e. fluorescence in situ hybridization – FISH, and related methods) are reviewed. We focus our review on the application of MAR‐FISH, Raman‐F... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5194824 Wed, 31 Aug 2011 23:00:00 +0100 5194824 http://www.medworm.com/index.php?rid=5156593&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00302.x AbstractTuberculosis remains a major health problem worldwide. Attempts to control this disease have proved difficult owing to our poor understanding of the pathobiology of Mycobacterium tuberculosis and the emergence of strains that are resistant to multiple drugs currently available for treatment. Genome‐wide expression profiling has provided new insight into the transcriptome signatures of the bacterium during infection, notably of macrophages and dendritic cells. These data indicate that M. tuberculosis expresses numerous genes to evade the host immune responses, to suit its intracellular life style, and to respond to various antibiotic drugs. Among the intracellularly induced genes, several have functions in lipid metabolism, cell wall synthesis, iron uptake, oxidative stress resist... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5156593 Thu, 25 Aug 2011 10:13:56 +0100 5156593 http://www.medworm.com/index.php?rid=5117858&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00301.x AbstractMost bacteria pathogenic for humans have closely related non‐pathogenic counterparts that live as saprophytes, commensals or even symbionts (mutualists) in similar or different habitats. The knowledge of how these bacteria adapt their metabolism to the preferred habitats is critical for our understanding of pathogenesis, commensalism and symbiosis, and ‐ in case of bacterial pathogens ‐ could help to identify targets for new antimicrobial agents. The focus of this review is on the metabolic potentials and adaptations of three different groups of human extra‐ and intracellular bacterial pathogens and their non‐pathogenic relatives. All bacteria selected have the potential to reach the interior of mammalian host cells. However, their ability to replicate intracellularly dif... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5117858 Thu, 11 Aug 2011 18:16:03 +0100 5117858 http://www.medworm.com/index.php?rid=5218221&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00301.x AbstractMost bacteria pathogenic for humans have closely related nonpathogenic counterparts that live as saprophytes, commensals or even symbionts (mutualists) in similar or different habitats. The knowledge of how these bacteria adapt their metabolism to the preferred habitats is critical for our understanding of pathogenesis, commensalism and symbiosis, and – in the case of bacterial pathogens – could help to identify targets for new antimicrobial agents. The focus of this review is on the metabolic potentials and adaptations of three different groups of human extra‐ and intracellular bacterial pathogens and their nonpathogenic relatives. All bacteria selected have the potential to reach the interior of mammalian host cells. However, their ability to replicate intracellularly diffe... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5218221 Wed, 10 Aug 2011 04:00:00 +0100 5218221 http://www.medworm.com/index.php?rid=5169186&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00300.x We describe the regularity of the position and structure of the AT‐rich regions in bacterial chromosomes and plasmids. The importance of 13‐nucleotide‐long repeats present at the AT‐rich region, as well as other motifs overlapping them, was pointed out to be essential for DNA replication initiation including origin opening, helicase loading and replication complex assembly. We also summarize the role of AT‐rich region repeated sequences for DNA replication regulation. (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5169186 Tue, 19 Jul 2011 23:00:00 +0100 5169186 http://www.medworm.com/index.php?rid=5048831&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00299.x ABSTRACTSergei Winogradsky, was born in Russia in 1856 and was to become a founder of modern microbiology. After his Master's degree work on the nutrition and growth physiology of the yeast Mycoderma vini at the University of St.Petersburg, he joined the laboratory of Anton DeBary in Strassburg. There he carried out his studies on the sulfur‐oxidizing bacterium Beggiatoa which resulted in his formulation of the theory of chemolithotrophy. He then joined the Swiss Polytechnic Institute in Zurich where he did his monumental work on bacterial nitrification. He isolated the first pure cultures of the nitrifying bacteria and confirmed that they carried out the separate steps of the conversion of ammonia to nitrite and of nitrite to nitrate. This led directly to the concept of the cycles of su... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5048831 Sun, 17 Jul 2011 23:00:00 +0100 5048831 http://www.medworm.com/index.php?rid=5007059&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00294.x AbstractThe emergence of antibiotic and antimicrobial resistance in Gram‐negative bacteria is incremental and linked with genetic elements that function in a so called ‘one ended transposition’ manner, including ISEcp1, ISCR elements and Tn3‐like transposons. The power of these elements lies in their inability to consistently recognise one of their own terminal sequences, whilst recognising more genetically distant surrogate sequences. This has the effect of mobilising DNA sequence found adjacent to their initial location. In general, resistance in Gram‐negatives is closely linked with a few one‐off events. These include: the capture of the class 1 integron by a Tn5090‐like transposon; the formation of the 3′ conserved segment (3′‐CS) and the fusion of the ISCR1 element... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5007059 Mon, 04 Jul 2011 23:00:00 +0100 5007059 http://www.medworm.com/index.php?rid=5048830&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00300.x We describe regularity of the position and structure of the AT‐rich regions in bacterial chromosomes and plasmids. The importance of 13‐nucleotide‐long repeats present at the AT‐rich region, as well as other motifs overlapping them, were pointed out to be essential for DNA replication initiation including origin opening, helicase loading and replication complex assembly. We also summarize the role of AT‐rich region repeated sequences for DNA replication regulation. (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5048830 Thu, 30 Jun 2011 23:00:00 +0100 5048830 http://www.medworm.com/index.php?rid=5027220&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00298.x AbstractUntil recently, microbial identification in clinical diagnostic laboratories has mainly relied on conventional phenotypic and gene sequencing identification techniques. The development of Matrix‐Assisted Laser Desorption Ionization Time‐Of‐Flight mass spectrometry (MALDI‐TOFMS) devices has revolutionized the routine identification of microorganisms in clinical microbiology laboratories by introducing an easy, rapid, high throughput, low‐cost and efficient identification technique. This technology has been adapted to the constraint of clinical diagnostic laboratories and has the potential to replace and/or complement conventional identification techniques for both bacterial and fungal strains. Using standardized procedures, the resolution of MALDI‐TOFMS allows accurate i... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5027220 Thu, 30 Jun 2011 23:00:00 +0100 5027220 http://www.medworm.com/index.php?rid=5018535&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00297.x AbstractProtozoan parasites of the genus Plasmodium are the causative agents of malaria. Despite more than 100 years of research, the complex life cycle of the parasite still bears many surprises and it is safe to say that understanding the biology of the pathogen will keep scientists busy for many years to come. Malaria research has mainly concentrated on the pathological blood stage of Plasmodium parasites, leaving us with many questions concerning the parasite development within the mosquito and during the exo‐erythrocytic stage in the vertebrate host. After the discovery of the Plasmodium liver stage in the middle of the last century, it remained understudied for many years but the realization that it represents a promising target for vaccination approaches has brought it back into f... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5018535 Thu, 30 Jun 2011 23:00:00 +0100 5018535 http://www.medworm.com/index.php?rid=5007058&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00296.x AbstractThe maize pathogen Ustilago maydis has to undergo various morphological transitions for the completion of its sexual life cycle. For example, haploid cells respond to pheromone by forming conjugation tubes that fuse at their tips. The resulting dikaryon grows filamentously expanding rapidly at the apex and inserting retraction septa at the basal pole. In this review, we present progress on the underlying mechanisms regulating such defined developmental programmes. Key findings of the postgenomic era are: (i) endosomes function not only during receptor recycling but also as multifunctional transport platforms; (ii) a new transcriptional master regulator for pathogenicity is part of an intricate transcriptional network; (iii) determinants for uniparental mitochondrial inheritance are... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5007058 Thu, 30 Jun 2011 23:00:00 +0100 5007058 http://www.medworm.com/index.php?rid=4992057&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00295.x AbstractWithin a susceptible wild‐type population, a small fraction of cells, even <10−9, is not affected when challenged by an antimicrobial agent. This subpopulation has mutations that impede antimicrobial action allowing their selection during clinical treatment. Emergence of resistance occurs in the frame of a selective compartment termed mutant selection window (MSW). The lower margin corresponds to the MIC of the susceptible cells, whereas the upper boundary, named mutant prevention concentration (MPC), restricts the growth of the whole population, including that of the resistant mutants. By combining pharmacokinetic/pharmacodynamic concepts and an MPC strategy, the selection of resistant mutants can be limited. Early treatment avoiding an increase of the inoculum size as well... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4992057 Thu, 30 Jun 2011 23:00:00 +0100 4992057 http://www.medworm.com/index.php?rid=4983878&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00293.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4983878 Thu, 30 Jun 2011 14:26:15 +0100 4983878 http://www.medworm.com/index.php?rid=4974976&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00292.x AbstractHorizontal genetic transfer (HGT) has played an important role in bacterial evolution at least since the origins of the bacterial divisions, and HGT still facilitates the origins of bacterial diversity, including diversity based on antibiotic resistance. Adaptive HGT is aided by unique features of genetic exchange in bacteria such as the promiscuity of genetic exchange and the shortness of segments transferred. Genetic exchange rates are limited by the genetic and ecological similarity of organisms. Adaptive transfer of genes is limited to those that can be transferred as a functional unit, provide a niche‐transcending adaptation, and are compatible with the architecture and physiology of other organisms. Horizontally transferred adaptations may bring about fitness costs, and nat... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4974976 Tue, 28 Jun 2011 20:04:31 +0100 4974976 http://www.medworm.com/index.php?rid=4974977&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00291.x AbstractPlasmids contain a backbone of core genes that remains relatively stable for long evolutionary periods, making sense to speak about plasmid species. The identification and characterization of the core genes of a plasmid species has a special relevance in the study of its epidemiology and modes of transmission. Besides, this knowledge will help to unveil the main routes that genes, for example antibiotic resistance (AbR) genes, use to travel from environmental reservoirs to human pathogens. Global dissemination of multiple antibiotic resistances and virulence traits by plasmids is an increasing threat for the treatment of many bacterial infectious diseases. To follow the dissemination of virulence and AbR genes we need to identify the causative plasmids and follow their path from re... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4974977 Mon, 27 Jun 2011 23:00:00 +0100 4974977 http://www.medworm.com/index.php?rid=5085454&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00288.x AbstractCircadian clocks organize our inner physiology with respect to the external world, providing life with the ability to anticipate and thereby better prepare for major fluctuations in its environment. Circadian systems are widely represented in nearly all major branches of life, except archaebacteria, and within the eukaryotes, the filamentous fungus Neurospora crassa has served for nearly half a century as a durable model organism for uncovering the basic circadian physiology and molecular biology. Studies using Neurospora have clarified our fundamental understanding of the clock as nested positive and negative feedback loops regulated through transcriptional and post‐transcriptional processes. These feedback loops are centered on a limited number of proteins that form molecular c... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5085454 Sun, 26 Jun 2011 23:00:00 +0100 5085454 http://www.medworm.com/index.php?rid=5076841&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00290.x AbstractAntibiotic resistance mechanisms reported in Gram‐negative bacteria are causing a worldwide health problem. The continuous dissemination of ‘multidrug‐resistant’ (MDR) bacteria drastically reduces the efficacy of our antibiotic ‘arsenal’ and consequently increases the frequency of therapeutic failure. In MDR bacteria, the overexpression of efflux pumps that expel structurally unrelated drugs contributes to the reduced susceptibility by decreasing the intracellular concentration of antibiotics. During the last decade, several clinical data have indicated an increasing involvement of efflux pumps in the emergence and dissemination of resistant Gram‐negative bacteria. It is necessary to clearly define the molecular, functional and genetic bases of the efflux pump in orde... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=5076841 Sun, 26 Jun 2011 23:00:00 +0100 5076841 http://www.medworm.com/index.php?rid=4974980&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00288.x AbstractCircadian clocks organize our inner physiology with respect to the external world providing life with the ability to anticipate and thereby better prepare for major fluctuations in its environment. Circadian systems are widely represented in nearly all major branches of life except archaebacteria, and within the eukaryotes the filamentous fungus Neurospora crassa has served for nearly half a century as a durable model organism for uncovering the basic circadian physiology and molecular biology. Studies using Neurospora have clarified our fundamental understanding of the clock as nested positive and negative feedback loops regulated through transcriptional and post‐transcriptional processes. These feedback loops are centered on a limited number of proteins that form molecular comp... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4974980 Sun, 26 Jun 2011 23:00:00 +0100 4974980 http://www.medworm.com/index.php?rid=4974979&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00289.x AbstractUnfortunately for mankind it is very likely that the antibiotic resistance problem we have generated during the last 60 years due to the extensive use and misuse of antibiotics is here to stay for the foreseeable future. This view is based on theoretical arguments, mathematical modeling, experiments and clinical interventions, suggesting that even if we could reduce antibiotic use, resistant clones would remain persistent and only slowly (if at all) be outcompeted by their susceptible relatives. In this review, we discuss the multitude of mechanisms and processes that are involved in causing persistence of chromosomal and plasmid borne resistance determinants, and how we might use them to our advantage to increase the likelihood of reversing the problem. Of particular interest is t... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4974979 Sun, 26 Jun 2011 23:00:00 +0100 4974979 http://www.medworm.com/index.php?rid=4974978&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00290.x AbstractAntibiotic resistance mechanisms reported in Gram‐negative bacteria are producing a worldwide health problem. The continuous dissemination of «multi‐drug resistant» (MDR) bacteria drastically reduces the efficacy of our antibiotic “arsenal” and consequently increases the frequency of therapeutic failure. In MDR bacteria, the over‐expression of efflux pumps that expel structurally‐unrelated drugs contributes to the reduced susceptibility by decreasing the intracellular concentration of antibiotics. During the last decade, several clinical data indicate an increasing involvement of efflux pumps in the emergence and dissemination of resistant Gram‐negative bacteria. It is necessary to clearly define the molecular, functional and genetic bases of the efflux pump in orde... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4974978 Sun, 26 Jun 2011 23:00:00 +0100 4974978 http://www.medworm.com/index.php?rid=4920440&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00287.x AbstractLike all microbes, yeast cells spend most of their natural lifetime in a reversible, quiescent state that is primarily induced by limitation for essential nutrients. Substantial progress has been made in defining the features of quiescent cells and the nutrient signaling pathways that shape these features. A view that emerges from the wealth of new data is that yeast cells dynamically configure the quiescent state in response to nutritional challenges by employing a set of key nutrient signaling pathways, which (i) regulate pathway‐specific effectors, (ii) converge on a few regulatory nodes that bundle multiple inputs to communicate unified, graded responses, and (iii) mutually modulate their competences to transmit signals. Here, I present an overview of our current understandin... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4920440 Sat, 11 Jun 2011 03:19:50 +0100 4920440 http://www.medworm.com/index.php?rid=4920444&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00283.x AbstractAntibiotic resistant Gram positive bacteria are responsible for morbidity and mortality in health care environments. Enterococcus faecium, Enterococcus faecalis, Staphylococcus aureus and Streptococcus pneumoniae all exhibit clinically relevant multidrug resistance phenotypes due to acquired resistance genes on mobile genetic elements. It is possible that clinically relevant multi‐drug resistant Clostridium difficile will appear in the future as the organism is adept at acquiring mobile genetic elements. This review will detail our current knowledge of the Tn916/Tn1545 family of conjugative transposons, including the major antibiotic resistance determinants which they carry and their biology in these different bacteria. Additionally we will highlight their ability to acquire addi... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4920444 Wed, 08 Jun 2011 23:00:00 +0100 4920444 http://www.medworm.com/index.php?rid=4920443&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00284.x AbstractInfections caused by multi‐resistant Gram positive bacteria represent a major health burden in the community as well as in hospitalized patients. Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium are well‐known pathogens of hospitalized patients, frequently linked with resistance against multiple antibiotics, compromising effective therapy. Streptococcus pneumoniae and Streptococcus pyogenes are important pathogens in the community and S. aureus has recently emerged as an important community‐acquired pathogen. Population genetic studies reveal that recombination prevails as a driving force of genetic diversity in E. faecium, E. faecalis, S. pneumoniae, and S. pyogenes and thus, these species are weakly clonal. Although recombination has a relatively modest... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4920443 Wed, 08 Jun 2011 23:00:00 +0100 4920443 http://www.medworm.com/index.php?rid=4920442&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00285.x AbstractFilamentous fungi produce a number of small bioactive molecules as part of their secondary metabolism ranging from benign antibiotics such as penicillin to threatening mycotoxins such as aflatoxin. Secondary metabolism can be linked to fungal developmental programs in response to various abiotic or biotic external triggers. The velvet family of regulatory proteins plays a key role in coordinating secondary metabolism and differentiation processes as asexual or sexual sporulation and sclerotia or fruiting body formation. The velvet family shares a protein domain that is present in most parts of the fungal kingdom from chytrids to basidiomycetes. Most of the current knowledge derives from the model A. nidulans where VeA, the founding member of the protein family was discovered almost... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4920442 Wed, 08 Jun 2011 23:00:00 +0100 4920442 http://www.medworm.com/index.php?rid=4920441&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00286.x AbstractThe ability of fungi to transition between unicellular and multicellular growth has a profound impact on our health and the economy. Many important fungal pathogens of humans, animals and plants are dimorphic, and the ability to switch between morphological states has been associated with their virulence. Cryptococcus neoformans is a human fungal pathogen that causes life‐threatening meningoencephalitis in immunocompromised and, in some cases, immunocompetent hosts. C. neoformans grows vegetatively as a budding yeast and switches to hyphal growth during the sexual cycle, which is important in the study of cryptococcal pathogenicity because spores resulting from sexual development are infectious propagules and can colonize the lungs of a host. In addition, sexual reproduction cont... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4920441 Wed, 08 Jun 2011 23:00:00 +0100 4920441 http://www.medworm.com/index.php?rid=4901688&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00282.x AbstractIt is generally assumed that antibiotics and resistance determinants are the task forces of a biological warfare in which each resistance determinant counteracts the activity of a specific antibiotic. Under this view, antibiotic resistance might be considered as a specific response to an injury, not necessarily linked to bacterial metabolism, excepting for the burden that the acquisition of resistance might impose to bacteria (fitness costs). Nevertheless, it is known that changes in bacterial metabolism, such as those associated to dormancy or to biofilm formation, modulate bacterial susceptibility to antibiotics (phenotypic resistance), indicating that there exists a linkage between bacterial metabolism and antibiotic resistance. The analyses of the intrinsic resistomes of bacter... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4901688 Mon, 06 Jun 2011 19:30:54 +0100 4901688 http://www.medworm.com/index.php?rid=4820010&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00278.x AbstractThe incidence of infections caused by Candida species (candidosis) has increased greatly over the past three decades, mainly due to the rise of the AIDS epidemic, an increasingly aged population, higher numbers of immunocompromised patients, and the more widespread use of indwelling medical devices. Candida albicans is the main cause of candidosis, however, non‐Candida albicans Candida species such as Candida glabrata, Candida tropicalis and Candida parapsilosis are now frequently identified as human pathogens. The apparent increased emergence of these species as human pathogens can be attributed to improved identification methods and also associated with the degree of diseases of the patients, the interventions that they were subjected and with the drugs used. Candida pathogenic... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4820010 Thu, 12 May 2011 23:00:00 +0100 4820010 http://www.medworm.com/index.php?rid=4820009&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00279.x AbstractGrowth rate regulation in bacteria has been an important issue in bacterial physiology for the past 50 years. This review, using E. coli as a paradigm, summarizes the mechanisms for the regulation of rRNA synthesis in the context of systems biology, particularly, in the context of genome‐wide competition for limited RNA polymerase in the cell under different growth conditions including nutrient starvation. The specific location of the seven rrn operons in the chromosome and the unique properties of the rrn promoters contribute to growth rate regulation. The length of the rrn transcripts, coupled with gene dosage effects, influence the distribution of RNAP on the chromosome in response to growth rate. Regulation of rRNA synthesis depends on multiple factors that affect the structu... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4820009 Thu, 12 May 2011 23:00:00 +0100 4820009 http://www.medworm.com/index.php?rid=4820011&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00277.x AbstractAntibiotic resistance in Gram‐negative bacteria is often due to acquisition of resistance genes from a shared pool. In multi‐resistant isolates these genes, together with associated mobile elements, may be found in complex conglomerations on plasmids or the chromosome. Analysis of available sequences reveals that these regions are modular, mosaic structures composed of different combinations of components from a limited set arranged in a limited number of ways. Components common to different regions provide targets for homologous recombination, allowing these regions to evolve by combinatorial evolution but our understanding of this process is far from complete. Advances in technology are leading to increasing amounts of sequence data but currently available automated annotatio... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4820011 Wed, 11 May 2011 23:00:00 +0100 4820011 http://www.medworm.com/index.php?rid=4871192&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00281.x AbstractThe history of research on microbial rhodopsins offers a novel perspective on the history of the molecular life sciences. Events in this history play important roles in the development of fields such as general microbiology, membrane research, bioenergetics, metagenomics and, very recently, neurobiology. New concepts, techniques, methods and fields have arisen as the results of microbial rhodopsin investigations. In addition, the history of microbial rhodopsins illuminates dynamic connections between basic and applied science, and hypothesis‐driven and data‐driven approaches. The story begins with the late nineteenth century discovery of microbes on salted fish and leads into ecological and taxonomical studies of halobacteria in hypersaline environments. These programmes were b... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4871192 Sat, 30 Apr 2011 23:00:00 +0100 4871192 http://www.medworm.com/index.php?rid=4820008&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00280.x AbstractSince their discovery in the early 80s, viruses that infect the third domain of life, the Archaea, have captivated our attention because of their virions' unusual morphologies and proteins, which lack homologues in extant databases. Moreover, the life cycles of these viruses have unusual features, as revealed by the recent discovery of a novel virus egress mechanism that involves the formation of specific pyramidal structures on the host cell surface. The available data elucidate the particular nature of the archaeal virosphere and shed light on questions concerning the origin and evolution of viruses and cells. In this review, we summarise the current knowledge of archeoviruses, their interaction with hosts and plasmids and their role in the evolution of life. (Source: FEMS Microb... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4820008 Sat, 30 Apr 2011 23:00:00 +0100 4820008 http://www.medworm.com/index.php?rid=4758282&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00276.x AbstractApproximately one third of the world's population is infected with Mycobacterium tuberculosis, the causative agent of tuberculosis. This bacterium has an unusual lipid rich cell wall containing a vast repertoire of antigens, providing a hydrophobic impermeable barrier against chemical drugs, thus representing an attractive target for vaccine and drug development. Apart from the mycolyl‐arabinogalactan‐peptidoglycan (mAGP) complex, mycobacteria possess several immunomodulatory constituents, notably lipomannan (LM) and lipoarabinomannan (LAM). The availability of whole genome sequences of M. tuberculosis and related bacilli over the past decade, has led to the identification and functional characterization of various enzymes and potential drug targets involved in the biosynthesis... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4758282 Thu, 28 Apr 2011 04:37:32 +0100 4758282 http://www.medworm.com/index.php?rid=4882866&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00276.x AbstractApproximately one third of the world's population is infected with Mycobacterium tuberculosis, the causative agent of tuberculosis. This bacterium has an unusual lipid‐rich cell wall containing a vast repertoire of antigens, providing a hydrophobic impermeable barrier against chemical drugs, thus representing an attractive target for vaccine and drug development. Apart from the mycolyl–arabinogalactan–peptidoglycan complex, mycobacteria possess several immunomodulatory constituents, notably lipomannan and lipoarabinomannan. The availability of whole‐genome sequences of M. tuberculosis and related bacilli over the past decade has led to the identification and functional characterization of various enzymes and the potential drug targets involved in the biosynthesis of these g... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4882866 Tue, 26 Apr 2011 23:00:00 +0100 4882866 http://www.medworm.com/index.php?rid=4847485&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00274.x AbstractHorizontal gene transfer (HGT) can create diversity in the genetic repertoire of a lineage. Successful gene transfer likely occurs more frequently between more closely related organisms, leading to the formation of higher‐level exchange groups that in some respects are comparable to single‐species populations. Genes that appear fixed in a single species can be replaced through distant homologs or iso‐functional analogs acquired through HGT. These genes may originate from other species or they may be acquired by an individual strain from the species pan‐genome. Because of their similarity to alleles in a population, we label these gene variants that are exchanged between related species as homeoalleles. In a case study, we show that biased gene transfer plays an important ro... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4847485 Tue, 26 Apr 2011 23:00:00 +0100 4847485 http://www.medworm.com/index.php?rid=4758284&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00274.x AbstractHorizontal gene transfer (HGT) can create diversity in the genetic repertoire of a lineage. Successful gene transfer likely occurs more frequently between more closely related organisms, leading to the formation of higher‐level exchange groups that in some respects are comparable to single‐species populations. Genes that appear fixed in a single species can be replaced through distant homologs or iso‐functional analogs acquired through HGT. These genes may originate from other species or they may be acquired by an individual strain from the species pan‐genome. Because of their similarity to alleles in a population, we label these gene variants that are exchanged between related species as homeoalleles. In a case study, we show that biased gene transfer plays an important ro... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4758284 Tue, 26 Apr 2011 23:00:00 +0100 4758284 http://www.medworm.com/index.php?rid=4758283&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00275.x AbstractThe budding yeast Saccharomyces cerevisiae is a eukaryotic microorganism that is able to choose between different unicellular and multicellular lifestyles. The potential of individual yeast cells to switch between different growth modes is of advantage for optimal dissemination, protection and substrate colonization at the population level. A crucial step in lifestyle adaptation is the control of self and foreign adhesion. For this purpose, S. cerevisiae contains a set of cell wall associated proteins, which confer adhesion to diverse biotic and abiotic surfaces. Here, we provide an overview of different aspects of S. cerevisiae adhesion, including a detailed description of known lifestyles, recent insights into adhesin structure and function and an outline of the complex regulator... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4758283 Tue, 26 Apr 2011 23:00:00 +0100 4758283 http://www.medworm.com/index.php?rid=4747214&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00273.x AbstractAntibiotics were one of the great discoveries of the 20th Century. However, resistance appeared even in the earliest years of the antibiotic era. Antibiotic resistance continues to get worse, despite the ever increasing resources devoted to combat the problem. One of the most important factors in development of resistance to antibiotics is the remarkable ability of bacteria to share genetic resources via Lateral Gene Transfer (LGT). LGT happens on a global scale, such that in theory, any gene in any organism anywhere in the microbial biosphere might be mobilized and spread. With sufficiently strong selection, any gene may spread to a point where it establishes a global presence. From an antibiotic resistance perspective, this means a resistance phenotype can appear in a diverse ran... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4747214 Mon, 25 Apr 2011 14:17:25 +0100 4747214 http://www.medworm.com/index.php?rid=4847484&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00273.x AbstractAntibiotics were one of the great discoveries of the 20th century. However, resistance appeared even in the earliest years of the antibiotic era. Antibiotic resistance continues to become worse, despite the ever‐increasing resources devoted to combat the problem. One of the most important factors in the development of resistance to antibiotics is the remarkable ability of bacteria to share genetic resources via Lateral Gene Transfer (LGT). LGT occurs on a global scale, such that in theory, any gene in any organism anywhere in the microbial biosphere might be mobilized and spread. With sufficiently strong selection, any gene may spread to a point where it establishes a global presence. From an antibiotic resistance perspective, this means that a resistance phenotype can appear in ... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4847484 Sun, 24 Apr 2011 23:00:00 +0100 4847484 http://www.medworm.com/index.php?rid=4747216&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00271.x AbstractA key feature of the virulence of many bacterial pathogens is the ability to deliver effector proteins into eukaryotic cells via a dedicated type three secretion system (T3SS). Many bacterial pathogens, including species of Chlamydia, Xanthomonas, Pseudomonas, Ralstonia, Shigella, Salmonella, Escherichia and Yersinia depend on the T3SS to cause disease. T3SS effectors constitute a large and diverse group of virulence proteins that mimic eukaryotic proteins in structure and function. A salient feature of bacterial effectors is their modular architecture, comprising domains or motifs that confer an array of subversive functions within the eukaryotic cell. These domains/motifs therefore represent a fascinating repertoire of molecular determinants with important roles during infection.... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4747216 Sun, 24 Apr 2011 23:00:00 +0100 4747216 http://www.medworm.com/index.php?rid=4747215&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00272.x AbstractIn all living organisms, the response to double strand breaks (DSBs) is critical for the maintenance of chromosome integrity. Homologous recombination (HR), which utilizes a homologous template to prime DNA synthesis and to restore genetic information lost at the DNA break site, is a complex multistep response. In Bacillus subtilis, this response can be subdivided into five general acts: (a) recognition of the break site(s) and formation of a repair centre (RC), which enable cells to commit to HR; (b) end‐processing of the broken end(s) by different avenues to generate a 3′‐tailed duplex and RecN‐mediated DSB ‘coordination’; (c) loading of RecA onto ssDNA at the RecN‐induced RC and concomitant DNA strand exchange; (d) branch migration and resolution, or dissolution, o... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4747215 Sun, 24 Apr 2011 23:00:00 +0100 4747215 http://www.medworm.com/index.php?rid=4610431&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00270.x AbstractAlong the human gastrointestinal tract, microorganisms are confronted with multiple barriers. Besides selective physical conditions, the epithelium is regularly replaced and covered with a protective mucus layer trapping immune molecules. Recent insights into host defense strategies show that the host selects the intestinal microbiota, particularly the mucosa‐associated microbial community. In this context, humans coevolved with thousands of intestinal microbial species that have adapted to provide host benefits, while avoiding pathogenic behavior that might destabilize their host interaction. While mucosal microorganisms would be crucial for immunological priming, luminal microorganisms would be important for nutrient digestion. Further, we propose that the intestinal microorgan... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4610431 Tue, 01 Mar 2011 00:00:00 +0100 4610431 http://www.medworm.com/index.php?rid=4531576&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00269.x AbstractMembers of the genus Pseudomonas inhabit a wide variety of environments, which is reflected in their versatile metabolic capacity and broad potential for adaptation to fluctuating environmental conditions. Here we examine and compare the genomes of a range of Pseudomonas spp. encompassing plant, insect, and human pathogens, and environmental saprophytes. In addition to a large number of allelic differences of common genes that confer regulatory and metabolic flexibility, genome analysis suggests many other factors contribute to the diversity and adaptability of Pseudomonas spp. Horizontal gene transfer has impacted the capability of pathogenic Pseudomonas spp. in terms of disease severity (P. aeruginosa) and specificity (P. syringae). Genome rearrangements likely contribute to adap... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4531576 Tue, 01 Mar 2011 00:00:00 +0100 4531576 http://www.medworm.com/index.php?rid=4531575&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00270.x AbstractAlong the human gastrointestinal tract, microbes are confronted with multiple barriers. Besides selective physical conditions, the epithelium is regularly replaced and covered with a protective mucus layer trapping immune molecules. Recent insights in host defense strategies show that the host selects the intestinal microbiota, particularly the mucosa‐associated microbial community. In this context, humans co‐evolved with thousands of intestinal microbial species that have adapted to provide host benefits, while avoiding pathogenic behavior that might destabilize their host interaction. While mucosal microbes would be crucial for immunological priming, luminal microbes would be important for nutrient digestion. Further, we propose the intestinal microbes also co‐evolved with ... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4531575 Tue, 01 Mar 2011 00:00:00 +0100 4531575 http://www.medworm.com/index.php?rid=4454909&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00268.x AbstractMulti‐locus sequence typing reveals that many bacterial species have a clonal structure and that some clones are widespread. This underlying phylogeny was not revealed by PFGE, a method better suited to short‐term outbreak investigation. Some global clones are multi‐resistant and it is easy to assume that these have disseminated from single foci. Such conclusions need caution however, unless there is a clear epidemiological trail, as with KPC carbapenemase‐positive Klebsiella pneumoniae ST258 from Greece to northwest Europe. Elsewhere, established clones may have repeatedly and independently acquired resistance. Thus, the global ST131 Escherichia coli clone most often has CTX‐M‐15 ESBL, but also occurs without ESBLs and as a host of many other ESBL types. We explore thi... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4454909 Thu, 10 Feb 2011 00:46:07 +0100 4454909 http://www.medworm.com/index.php?rid=4570221&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00267.x AbstractS‐adenosyl‐l‐methionine (SAM)‐dependent methyltransferases represent a diverse group of enzymes that catalyze the transfer of a methyl group from a methyl donor SAM to nitrogen, oxygen, sulfur or carbon atoms of a large number of biologically active large and small molecules. These modifications play a major role in the regulation of various biological functions such as gene expression, signaling, nuclear division and metabolism. The three‐step SAM‐dependent methylation of phosphoethanolamine to form phosphocholine catalyzed by phosphoethanolamine N‐methyltransferases (PMTs) has emerged as an important biochemical step in the synthesis of the major phospholipid, phosphatidylcholine, in some eukaryotes. PMTs have been identified in nematodes, plants, African clawed fro... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4570221 Wed, 09 Feb 2011 00:00:00 +0100 4570221 http://www.medworm.com/index.php?rid=4535709&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00268.x AbstractMultilocus sequence typing reveals that many bacterial species have a clonal structure and that some clones are widespread. This underlying phylogeny was not revealed by pulsed‐field gel electrophoresis, a method better suited to short‐term outbreak investigation. Some global clones are multiresistant and it is easy to assume that these have disseminated from single foci. Such conclusions need caution, however, unless there is a clear epidemiological trail, as with KPC carbapenemase‐positive Klebsiella pneumoniae ST258 from Greece to northwest Europe. Elsewhere, established clones may have repeatedly and independently acquired resistance. Thus, the global ST131 Escherichia coli clone most often has CTX‐M‐15 extended‐spectrum β‐lactamase (ESBL), but also occurs withou... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4535709 Wed, 09 Feb 2011 00:00:00 +0100 4535709 http://www.medworm.com/index.php?rid=4454910&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00267.x AbstractS‐adenosyl‐L‐methionine‐dependent methyltransferases represent a diverse group of enzymes that catalyze the transfer of a methyl group from a methyl donor S‐adenosyl‐L‐methionine to nitrogen, oxygen, sulfur or carbon atoms of a large number of biologically active large and small molecules. These modifications play a major role in the regulation of various biological functions such as gene expression, signaling, nuclear division and metabolism. The three‐step S‐adenosyl‐L‐methionione‐dependent methylation of phosphoethanolamine to form phosphocholine catalyzed by phosphoethanolamine N‐methyltransferases has emerged as an important biochemical step in the synthesis of the major phospholipid, phosphatidylcholine, in some eukaryotes. Phosphoethanolamine N‐me... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4454910 Wed, 09 Feb 2011 00:00:00 +0100 4454910 http://www.medworm.com/index.php?rid=4501221&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00266.x AbstractResearch on freshwater fungi has concentrated on their role in plant litter decomposition in streams. Higher fungi dominate over bacteria in terms of biomass, production and enzymatic substrate degradation. Microscopy‐based studies suggest the prevalence of aquatic hyphomycetes, characterized by tetraradiate or sigmoid spores. Molecular studies have consistently demonstrated the presence of other fungal groups, whose contributions to decomposition are largely unknown. Molecular methods will allow quantification of these and other microorganisms. The ability of aquatic hyphomycetes to withstand or mitigate anthropogenic stresses is becoming increasingly important. Metal avoidance and tolerance in freshwater fungi implicate a sophisticated network of mechanisms involving external a... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4501221 Sat, 29 Jan 2011 00:00:00 +0100 4501221 http://www.medworm.com/index.php?rid=4337427&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00261.x AbstractLateral genetic transfer is a major source of phenotypic innovation among bacteria. Determinants for antibiotic resistance and other adaptive traits can spread rapidly, particularly by conjugative plasmids but also phages and natural transformation. Each successive step from the uptake of foreign DNA, its genetic recombination and regulatory integration, to its establishment in the host population presents differential barriers and opportunities. The emergence of successive multidrug‐resistant strains of Staphylococcus aureus illustrates the ongoing role of lateral genetic transfer in the combinatorial assembly of pathogens. The dynamic interplay among hosts, vectors, DNA elements, combinations of genetic determinants, and environments constructs communities of genetic exchange. ... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4337427 Tue, 11 Jan 2011 00:00:00 +0100 4337427 http://www.medworm.com/index.php?rid=4337426&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00262.x AbstractCompared to the impressive progress in understanding signal transduction pathways and mechanisms in mammalian systems, advances in protozoan signalling processes, including cyclic nucleotide metabolism, has been very slow. This is in large part connected to the fact that the components of these pathways are very different in the protozoan parasites, as confirmed by the recently completed genome. For instance, kinetoplastids have no equivalents to the mammalian class I adenylyl cyclases in their genomes, nor any of the subunits of the associated G‐proteins. The cyclases in kinetoplastid parasites contain a single trans‐membrane domain, a conserved intracellular catalytic domain and a highly variable extracellular domain – consistent with the expression of multiple receptor‐a... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4337426 Tue, 11 Jan 2011 00:00:00 +0100 4337426 http://www.medworm.com/index.php?rid=4414410&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00266.x AbstractResearch on freshwater fungi has concentrated on their role in plant litter decomposition in streams. Higher fungi dominate over bacteria in terms of biomass, production and enzymatic substrate degradation. Microsopy‐based studies suggest the prevalence of aquatic hyphomycetes, characterized by tetraradiate or sigmoid spores. Molecular studies have consistently demonstrated the presence of other fungal groups, whose contributions to decomposition are largely unknown. Molecular methods will allow quantification of these and other microorganisms. The ability of aquatic hyphomycetes to withstand or mitigate anthropogenic stresses is becoming increasingly important. Metal avoidance and tolerance in freshwater fungi implicate a sophisticated network of mechanisms involving external an... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4414410 Sat, 01 Jan 2011 00:00:00 +0100 4414410 http://www.medworm.com/index.php?rid=4399121&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00265.x AbstractThe tree of life is split into three main branches, eukaryotes, bacteria and archaea. Our knowledge of eukaryotic and bacteria cell biology has been built on a foundation of studies in model organisms, using the complementary approaches of genetics and biochemistry. Archaea have led to some exciting discoveries in the field of biochemistry, but archaeal genetics has been slow to get off the ground, not least because these organisms inhabit some of the more inhospitable places on earth and are therefore believed to be difficult to culture. In fact, many species can be cultivated with relative ease and there has been tremendous progress in the development of genetic tools for both major archaeal phyla, the Euryarchaeota and the Crenarchaeota. There are several model organisms availab... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4399121 Sat, 01 Jan 2011 00:00:00 +0100 4399121 http://www.medworm.com/index.php?rid=4377165&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2011.00264.x AbstractPhytopathogens have evolved specialized pathogenicity determinants that enable them to colonize their specific plant hosts and cause disease; but, their intimate associations with plants also predisposes them to frequent encounters with herbivorous insects, providing these phytopathogens with ample opportunity to colonize and eventually evolve alternative associations with insects. Decades of research have revealed that these associations have resulted in the formation of bacterial‐vector relationships, in which the insect mediates dissemination of the plant pathogen. Emerging research, however, has highlighted the ability of plant pathogenic bacteria to use insects as alternative hosts, exploiting them as they would their primary plant host. The identification of specific bacter... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4377165 Sat, 01 Jan 2011 00:00:00 +0100 4377165 http://www.medworm.com/index.php?rid=4337425&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00263.x AbstractPlant pathogenic fungi adapt quickly to changing environments including overcoming plant disease resistance genes. This is usually achieved by mutations in single effector genes of the pathogens enabling them to avoid recognition by the host plant. In addition, horizontal gene transfer (HGT) and horizontal chromosome transfer (HCT) provide means to pathogens to broaden their host range. Recently, several reports have appeared in literature on HGT, HCT and hybridization between plant pathogenic fungi that affect their host range including species of Stagonospora/Pyrenophora, Fusarium and Alternaria. Evidence is given that HGT of the ToxA gene from Stagonospora nodorum to Pyrenophora tritici‐repentis enabled the latter fungus to cause a serious disease on wheat. A non‐pathogenic ... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4337425 Sat, 01 Jan 2011 00:00:00 +0100 4337425 http://www.medworm.com/index.php?rid=4241373&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00260.x AbstractNeisseria meningitidis and Neisseria gonorrhoeae are globally important pathogens, which in part owe their success to their ability to successfully evade human immune responses over long periods. The phase variable Opacity‐associated (Opa) adhesin proteins are a major surface component of these organisms, and are responsible for bacterial adherence and entry into host cells and interactions with the immune system. Most immune interactions are mediated via binding to members of the carcinoembryonic antigen cell adhesion molecule (CEACAM) family. These Opa variants are able to bind to different receptors of the CEACAM family on epithelial cells, neutrophils, and T and B lymphocytes, influencing the innate and adaptive immune responses. Increased epithelial cell adhesion creates the... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4241373 Thu, 09 Dec 2010 01:01:05 +0100 4241373 http://www.medworm.com/index.php?rid=4360421&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00260.x AbstractNeisseria meningitidis and Neisseria gonorrhoeae are globally important pathogens, which in part owe their success to their ability to successfully evade human immune responses over long periods. The phase‐variable opacity‐associated (Opa) adhesin proteins are a major surface component of these organisms, and are responsible for bacterial adherence and entry into host cells and interactions with the immune system. Most immune interactions are mediated via binding to members of the carcinoembryonic antigen cell adhesion molecule (CEACAM) family. These Opa variants are able to bind to different receptors of the CEACAM family on epithelial cells, neutrophils, and T and B lymphocytes, influencing the innate and adaptive immune responses. Increased epithelial cell adhesion creates t... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4360421 Mon, 06 Dec 2010 00:00:00 +0100 4360421 http://www.medworm.com/index.php?rid=4224649&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00256.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4224649 Fri, 03 Dec 2010 00:00:00 +0100 4224649 http://www.medworm.com/index.php?rid=4182757&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00258.x AbstractSea‐surface warming, sea‐ice melting and related freshening, changes in circulation and mixing regimes and ocean acidification induced by the present climate changes are modifying marine ecosystem structure and function and have the potential to alter the cycling of carbon and nutrients in surface oceans. Changing climate has direct and indirect consequences on marine viruses, including cascading effects on biogeochemical cycles, food webs and the metabolic balance of the ocean. We discuss here a range of case studies of climate change and the potential consequences on virus function, viral assemblages and virus‐host interactions. In turn, marine viruses influence directly and indirectly biogeochemical cycles, C sequestration capacity of the oceans and the gas exchange betwee... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4182757 Fri, 19 Nov 2010 00:00:00 +0100 4182757 http://www.medworm.com/index.php?rid=4182756&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00259.x AbstractAll organisms that produce fatty acids do so via a repeated cycle of reactions. In mammals and other animals, these reactions are catalyzed by a type I fatty acid synthase (FAS), a large multifunctional protein to which the growing chain is covalently attached. In contrast, most bacteria (and plants) contain a type II system in which each reaction is catalyzed by a discrete protein. The pathway of fatty acid biosynthesis in Escherichia coli is well established and has provided a foundation for elucidating the type II FAS pathways in other bacteria (White et al., 2005). However, fatty acid biosynthesis is more diverse in the phylum Actinobacteria: Mycobacterium, possess both FAS systems while Streptomyces species have only the multi‐enzyme FAS II system and Corynebacterium species... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4182756 Mon, 01 Nov 2010 00:00:00 +0100 4182756 http://www.medworm.com/index.php?rid=4175295&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00257.x AbstractPertussis, or whooping cough, is a highly contagious, acute respiratory disease of humans that is caused by the Gram‐negative bacterial pathogen Bordetella pertussis. In the face of extensive global vaccination, this extremely monomorphic pathogen has persisted and reemerged, causing approximately 300 000 deaths each year. In this review we discuss the interaction of B. pertussis with the host mucosal epithelium and immune system. Using a large number of virulence factors, B. pertussis is able to create a niche for colonization in the human respiratory tract. The successful persistence of this pathogen is mainly due to its ability to interfere with almost every aspect of the immune system, from the inhibition of complement‐ and phagocyte‐mediated killing to the suppression ... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4175295 Mon, 01 Nov 2010 00:00:00 +0100 4175295 http://www.medworm.com/index.php?rid=4064874&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00255.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4064874 Thu, 14 Oct 2010 09:35:29 +0100 4064874 http://www.medworm.com/index.php?rid=4081592&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00252.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4081592 Thu, 30 Sep 2010 23:00:00 +0100 4081592 http://www.medworm.com/index.php?rid=4012099&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00254.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=4012099 Tue, 31 Aug 2010 23:00:00 +0100 4012099 http://www.medworm.com/index.php?rid=3998312&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00253.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3998312 Tue, 31 Aug 2010 23:00:00 +0100 3998312 http://www.medworm.com/index.php?rid=3993018&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00251.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3993018 Tue, 31 Aug 2010 23:00:00 +0100 3993018 http://www.medworm.com/index.php?rid=3993017&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00252.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3993017 Tue, 31 Aug 2010 23:00:00 +0100 3993017 http://www.medworm.com/index.php?rid=3934383&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00250.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3934383 Tue, 31 Aug 2010 23:00:00 +0100 3934383 http://www.medworm.com/index.php?rid=3815952&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00243.x This article provides an update on our current understanding of FnBPs from both Gram-negative and Gram-positive bacteria and their proposed roles in bacterial colonization, bacterial virulence and bacteria[ndash]host interactions. (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3815952 Tue, 03 Aug 2010 23:00:00 +0100 3815952 http://www.medworm.com/index.php?rid=3907143&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00249.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3907143 Sat, 31 Jul 2010 23:00:00 +0100 3907143 http://www.medworm.com/index.php?rid=3880478&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00246.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3880478 Sat, 31 Jul 2010 23:00:00 +0100 3880478 http://www.medworm.com/index.php?rid=3805576&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00245.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3805576 Fri, 30 Jul 2010 23:00:00 +0100 3805576 http://www.medworm.com/index.php?rid=3790286&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00242.x The continuous degradation and synthesis of prokaryotic mRNAs not only give rise to the metabolic changes that are required as cells grow and divide but also rapid adaptation to new environmental conditions. In bacteria, RNAs can be degraded by mechanisms that act independently, but in parallel, and that target different sites with different efficiencies. The accessibility of sites for degradation depends on several factors, including RNA higher-order structure, protection by translating ribosomes and polyadenylation status. Furthermore, RNA degradation mechanisms have shown to be determinant for the post-transcriptional control of gene expression. RNases mediate the processing, decay and quality control of RNA. RNases can be divided into endonucleases that cleave the RNA internally or exo... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3790286 Mon, 26 Jul 2010 23:00:00 +0100 3790286 http://www.medworm.com/index.php?rid=3775964&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00241.x Bacteria use a range of RNA regulators collectively termed small RNAs (sRNAs) to help respond to changes in the environment. Many sRNAs regulate their target mRNAs through limited base-pairing interactions. Ongoing characterization of base-pairing sRNAs in bacteria has started to reveal how these sRNAs participate in global regulatory networks. These networks can be broken down into smaller regulatory circuits that have characteristic behaviors and functions. In this review, we describe the specific regulatory circuits that incorporate base-pairing sRNAs and the importance of each circuit in global regulation. Because most of these circuits were originally identified as network motifs in transcriptional networks, we also discuss why sRNAs may be used over protein transcription factors to h... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3775964 Wed, 21 Jul 2010 23:00:00 +0100 3775964 http://www.medworm.com/index.php?rid=3761205&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00240.x The bacterial phage shock protein (Psp) response functions to help cells manage the impacts of agents impairing cell membrane function. The system has relevance to biotechnology and to medicine. Originally discovered in Escherichia coli, Psp proteins and homologues are found in Gram-positive and Gram-negative bacteria, in archaea and in plants. Study of the E. coli and Yersinia enterocolitica Psp systems provides insights into how membrane-associated sensory Psp proteins might perceive membrane stress, signal to the transcription apparatus and use an ATP-hydrolysing transcription activator to produce effector proteins to overcome the stress. Progress in understanding the mechanism of signal transduction by the membrane-bound Psp proteins, regulation of the psp gene-specific transcription a... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3761205 Fri, 16 Jul 2010 23:00:00 +0100 3761205 http://www.medworm.com/index.php?rid=3746475&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00239.x Gene transcription is a fundamental cellular process carried out by RNA polymerase (RNAP) enzymes and is highly regulated through the action of gene regulatory complexes. Important mechanistic insights have been gained from structural studies on multisubunit RNAP from bacteria, yeast and archaea, although the initiation process that involves the conversion of the inactive transcription complex to an active one has yet to be fully understood. RNAPs are unambiguously closely related in structure and function across all kingdoms of life and have conserved mechanisms. In bacteria, sigma ([sigma]) factors direct RNAP to specific promoter sites and the RNAP/[sigma] holoenzyme can either form a stable closed complex that is incompetent for transcription (as in the case of [sigma]54) or can sponta... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3746475 Mon, 12 Jul 2010 23:00:00 +0100 3746475 http://www.medworm.com/index.php?rid=3721496&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00234.x High and changing salt concentrations represent major abiotic factors limiting the growth of microorganisms. During their long evolution, cyanobacteria have adapted to aquatic habitats with various salt concentrations. High salt concentrations in the medium challenge the cell with reduced water availability and high contents of inorganic ions. The basic mechanism of salt acclimation involves the active extrusion of toxic inorganic ions and the accumulation of compatible solutes, including sucrose, trehalose, glucosylglycerol, and glycine betaine. The kinetics of these physiological processes has been exceptionally well studied in the model Synechocystis 6803, leading to the definition of five subsequent phases in reaching a new salt acclimation steady state. Recent '-omics' technologies us... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3721496 Fri, 02 Jul 2010 23:00:00 +0100 3721496 http://www.medworm.com/index.php?rid=3815953&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00244.x Members of the genus Bacillus are known to produce a wide arsenal of antimicrobial substances, including peptide and lipopeptide antibiotics, and bacteriocins. Many of the Bacillus bacteriocins belong to the lantibiotics, a category of post-translationally modified peptides widely disseminated among different bacterial clades. Lantibiotics are among the best-characterized antimicrobial peptides at the levels of peptide structure, genetic determinants and biosynthesis mechanisms. Members of the genus Bacillus also produce many other nonmodified bacteriocins, some of which resemble the pediocin-like bacteriocins of the lactic acid bacteria (LAB), while others show completely novel peptide sequences. Bacillus bacteriocins are increasingly becoming more important due to their sometimes broader... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3815953 Thu, 01 Jul 2010 23:00:00 +0100 3815953 http://www.medworm.com/index.php?rid=3842902&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00216.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842902 Wed, 30 Jun 2010 23:00:00 +0100 3842902 http://www.medworm.com/index.php?rid=3842901&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00214.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842901 Wed, 30 Jun 2010 23:00:00 +0100 3842901 http://www.medworm.com/index.php?rid=3842900&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00215.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842900 Wed, 30 Jun 2010 23:00:00 +0100 3842900 http://www.medworm.com/index.php?rid=3842899&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00213.x Abstract (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842899 Wed, 30 Jun 2010 23:00:00 +0100 3842899 http://www.medworm.com/index.php?rid=3842889&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00245.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842889 Wed, 30 Jun 2010 23:00:00 +0100 3842889 http://www.medworm.com/index.php?rid=3842888&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00243.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842888 Wed, 30 Jun 2010 23:00:00 +0100 3842888 http://www.medworm.com/index.php?rid=3842887&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00244.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842887 Wed, 30 Jun 2010 23:00:00 +0100 3842887 http://www.medworm.com/index.php?rid=3842886&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00246.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842886 Wed, 30 Jun 2010 23:00:00 +0100 3842886 http://www.medworm.com/index.php?rid=3842885&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00247.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842885 Wed, 30 Jun 2010 23:00:00 +0100 3842885 http://www.medworm.com/index.php?rid=3842884&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00248.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842884 Wed, 30 Jun 2010 23:00:00 +0100 3842884 http://www.medworm.com/index.php?rid=3842883&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00249.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842883 Wed, 30 Jun 2010 23:00:00 +0100 3842883 http://www.medworm.com/index.php?rid=3695164&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00237.x Cystic fibrosis (CF), the most common autosomal recessive disorder in Caucasians, and chronic obstructive pulmonary disease (COPD), a disease of adults, are characterized by chronic lung inflammation, airflow obstruction and extensive tissue remodelling, which have a major impact on patients' morbidity and mortality. Airway inflammation is stimulated in CF by chronic bacterial infections and in COPD by environmental stimuli, particularly from smoking. Pseudomonas aeruginosa is the major bacterial pathogen in CF, while in COPD, Haemophilus influenzae is most frequently observed. Molecular studies indicate that during chronic pulmonary infection, P. aeruginosa clones genotypically and phenotypically adapt to the CF niche, resulting in a highly diverse bacterial community that is difficult to... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3695164 Thu, 24 Jun 2010 23:00:00 +0100 3695164 http://www.medworm.com/index.php?rid=3721497&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00238.x A large number of prokaryotic regulatory elements have been interfaced artificially with biological circuits that execute specific expression programs. Engineering such circuits involves the association of input/output components that perform discrete signal-transfer steps in an autonomous fashion while connected to the rest of the network with a defined topology. Each of these nodes includes a signal-recognition component for the detection of the relevant physicochemical or biological stimulus, a molecular device able to translate the signal-sensing event into a defined output and a genetic module capable of understanding such an output as an input for the next component of the circuit. The final outcome of the process can be recorded by means of a reporter product. This review addresses ... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3721497 Sun, 06 Jun 2010 23:00:00 +0100 3721497 http://www.medworm.com/index.php?rid=3842891&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00233.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842891 Mon, 31 May 2010 23:00:00 +0100 3842891 http://www.medworm.com/index.php?rid=3842890&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00236.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842890 Mon, 31 May 2010 23:00:00 +0100 3842890 http://www.medworm.com/index.php?rid=3609998&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00232.x Infections caused by Candida spp. continue to be a substantial cause of disease burden, especially in immunocompromised patients. New approaches are needed to improve the outcome of patients suffering from Candida infections, because it seems unlikely that the established standard treatment will drastically lower the morbidity of mucocutaneous Candida infections and the high mortality associated with invasive candidiasis. New insights into the mechanisms of the anti-Candida host response have contributed to the design of novel immunotherapeutic approaches that have been proposed as adjuvant therapy in Candida infections. This review presents an overview of novel strategies in the prevention and treatment of Candida infections, with a special focus on adjuvant immunotherapy. (Source: FEMS M... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3609998 Fri, 28 May 2010 23:00:00 +0100 3609998 http://www.medworm.com/index.php?rid=3695165&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00236.x The tripartite ATP-independent periplasmic (TRAP) transporters are the best-studied family of substrate-binding protein (SBP)-dependent secondary transporters and are ubiquitous in prokaryotes, but absent from eukaryotes. They are comprised of an SBP of the DctP or TAXI families and two integral membrane proteins of unequal sizes that form the DctQ and DctM protein families, respectively. The SBP component has a structure comprised of two domains connected by a hinge that closes upon substrate binding. In DctP-TRAP transporters, substrate binding is mediated through a conserved and specific arginine/carboxylate interaction in the SBP. While the SBP component has now been relatively well characterized, the membrane components of TRAP transporters are still poorly understood both in terms of... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3695165 Thu, 27 May 2010 23:00:00 +0100 3695165 http://www.medworm.com/index.php?rid=3607202&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00231.x Repeats-in-toxin (RTX) exoproteins of Gram-negative bacteria form a steadily growing family of proteins with diverse biological functions. Their common feature is the unique mode of export across the bacterial envelope via the type I secretion system and the characteristic, typically nonapeptide, glycine- and aspartate-rich repeats binding Ca2+ ions. In this review, we summarize the current state of knowledge on the organization of rtx loci and on the biological and biochemical activities of therein encoded proteins. Applying several types of bioinformatic screens on the steadily growing set of sequenced bacterial genomes, over 1000 RTX family members were detected, with the biological functions of most of them remaining to be characterized. Activities of the so far characterized RTX famil... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3607202 Thu, 27 May 2010 23:00:00 +0100 3607202 http://www.medworm.com/index.php?rid=3595297&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00229.x The gram-negative bacterium Proteus mirabilis can exist in either of two cell types, a vegetative cell characterized as a short rod and a highly elongated and hyperflagellated swarmer cell. This differentiation is triggered by growth on solid surfaces and multiple inputs are sensed by the cell to initiate the differentiation process. These include the inhibition of flagellar rotation, the accumulation of extracellular putrescine and O-antigen interactions with a surface. A key event in the differentiation process is the upregulation of FlhD2C2, which activates the flagellar regulon and additional genes required for differentiation. There are a number of genes that influence FlhD2C2 expression and the function of these genes, if known, will be discussed in this review. Additional genes that... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3595297 Mon, 24 May 2010 23:00:00 +0100 3595297 http://www.medworm.com/index.php?rid=3588706&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00230.x Since their discovery in the 1960s as 'osmotic shock-sensitive' transporters, a plethora of so-called binding protein-dependent (canonical) ATP-binding cassette (ABC) importers has been identified in bacteria and archaea. Their cellular functions go far beyond the uptake of nutrients. Canonical ABC importers play important roles in the maintenance of cell integrity, responses to environmental stresses, cell-to-cell communication and cell differentiation and in pathogenicity. A new class of abundant micronutrient importers, the 'energy-coupling factor' (ECF) transporters, was originally identified by functional genomics. ABC ATPases are an integral part of both canonical ABC and ECF importers. Fundamental differences include the modular architecture and the independence of ECF systems of ex... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3588706 Fri, 21 May 2010 23:00:00 +0100 3588706 http://www.medworm.com/index.php?rid=3671199&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00235.x A global regulatory complex made up of two unconventional transcriptional factors, CarD and CarG, is implicated in the control of various processes in Myxococcus xanthus, a Gram-negative bacterium that serves as a prokaryotic model system for multicellular development and the response to blue light. CarD has a unique two-domain architecture composed of: (1) a C-terminal DNA-binding domain that resembles eukaryotic high mobility group A (HMGA) proteins, which are relatively abundant, nonhistone components of chromatin that remodel DNA and prime it for the assembly of multiprotein[ndash]DNA complexes essential for various DNA transactions, and (2) an N-terminal domain involved in interactions with CarG and RNA polymerase, which is also the founding member of the large CarD_TRCF family of bac... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3671199 Wed, 19 May 2010 23:00:00 +0100 3671199 http://www.medworm.com/index.php?rid=3695166&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00233.x The ability of Helicobacter pylori, one of the most successful human bacterial pathogens, to colonize the acidic gastric niche persistently, depends on the proper homeostasis of intracellular metal ions, needed as cofactors of essential metallo-proteins involved in acid acclimation, respiration and detoxification. This fundamental task is controlled at the transcriptional level mainly by the regulators Fur and NikR, involved in iron homeostasis and nickel response, respectively. Herein, we review the molecular mechanisms that underlie the activity of these key pleiotropic regulators. In addition, we will focus on their involvement in the transcriptional regulatory network of the bacterium, pinpointing a surprising complexity of network motifs that interconnects them and their gene targets.... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3695166 Tue, 18 May 2010 23:00:00 +0100 3695166 http://www.medworm.com/index.php?rid=3577041&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00227.x The vast majority of experimental data have been accumulated on the transcription regulation of individual genes within a single model prokaryote, Escherichia coli, which form the well-established on[ndash]off switch model of transcription by DNA-binding regulatory proteins. After the development of modern high-throughput experimental systems such as microarray analysis of whole genome transcription and the Genomic SELEX search for the whole set of regulation targets by transcription factors, a number of E. coli promoters are now recognized to be under the control of multiple transcription factors, as in the case of eukaryotes. The number of regulation targets of a single transcription factor has also been found to be more than hitherto recognized, ranging up to hundreds of promoters, gene... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3577041 Tue, 18 May 2010 23:00:00 +0100 3577041 http://www.medworm.com/index.php?rid=3559891&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00228.x We describe the functional classification of the detected transcription regulators and their interactions in the gene-regulatory network. Moreover, we provide an overview of the molecular features of transcription regulators and their regulons to integrate these data into the gene-regulatory network and to unravel the flow of information from the environment toward the gene level. (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3559891 Wed, 12 May 2010 23:00:00 +0100 3559891 http://www.medworm.com/index.php?rid=3842894&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00223.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842894 Fri, 30 Apr 2010 23:00:00 +0100 3842894 http://www.medworm.com/index.php?rid=3842893&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00226.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842893 Fri, 30 Apr 2010 23:00:00 +0100 3842893 http://www.medworm.com/index.php?rid=3842892&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00230.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842892 Fri, 30 Apr 2010 23:00:00 +0100 3842892 http://www.medworm.com/index.php?rid=3490235&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00221.x Lipopeptides constitute a structurally diverse group of metabolites produced by various bacterial and fungal genera. In the past decades, research on lipopeptides has been fueled by their antimicrobial, antitumour, immunosuppressant and surfactant activities. However, the natural functions of lipopeptides in the lifestyles of the producing microorganisms have received considerably less attention. The substantial structural diversity of lipopeptides suggests that these metabolites have different natural roles, some of which may be unique to the biology of the producing organism. This review gives a detailed overview of the versatile functions of lipopeptides in the biology of Pseudomonas and Bacillus species, and highlights their role in competitive interactions with coexisting organisms, i... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3490235 Tue, 20 Apr 2010 23:00:00 +0100 3490235 http://www.medworm.com/index.php?rid=3490237&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00224.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3490237 Mon, 19 Apr 2010 23:00:00 +0100 3490237 http://www.medworm.com/index.php?rid=3486530&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00222.x TEM-1 [beta]-lactamase is one of the most well-known antibiotic resistance determinants around. It confers resistance to penicillins and early cephalosporins and has shown an astonishing functional plasticity in response to the introduction of novel drugs derived from these antibiotics. Since its discovery in the 1960s, over 170 variants of TEM-1 [ndash] with different amino acid sequences and often resistance phenotypes [ndash] have been isolated in hospitals and clinics worldwide. Next to this well-documented 'natural' evolution, the in vitro evolution of TEM-1 has been the focus of attention of many experimental studies. In this review, we compare the natural and laboratory evolution of TEM-1 in order to address the question to what extent the evolution of antibiotic resistance can be r... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3486530 Mon, 19 Apr 2010 23:00:00 +0100 3486530 http://www.medworm.com/index.php?rid=3459885&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00220.x Microorganisms have the capacity to utilize a variety of nutrients and adapt to continuously changing environmental conditions. Many microorganisms, including yeast and bacteria, accumulate carbon and energy reserves to cope with the starvation conditions temporarily present in the environment. Glycogen biosynthesis is a main strategy for such metabolic storage, and a variety of sensing and signaling mechanisms have evolved in evolutionarily distant species to ensure the production of this homopolysaccharide. At the most fundamental level, the processes of glycogen synthesis and degradation in yeast and bacteria share certain broad similarities. However, the regulation of these processes is sometimes quite distinct, indicating that they have evolved separately to respond optimally to the h... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3459885 Sun, 11 Apr 2010 23:00:00 +0100 3459885 http://www.medworm.com/index.php?rid=3577043&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00226.x This review covers the physiological aspects of regulation of the arabinose operon in Escherichia coli and the physical and regulatory properties of the operon's controlling gene, araC. It also describes the light switch mechanism as an explanation for many of the protein's properties. Although many thousands of homologs of AraC exist and regulate many diverse operons in response to many different inducers or physiological states, homologs that regulate arabinose-catabolizing genes in response to arabinose were identified. The sequence similarities among them are discussed in light of the known structure of the dimerization and DNA-binding domains of AraC. (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3577043 Wed, 07 Apr 2010 23:00:00 +0100 3577043 http://www.medworm.com/index.php?rid=3559892&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00225.x The fungal wall contains a small proportion of alkali-extractable water-soluble heteromannans (F1SS). They are the glycidic moiety of glycoproteins that have important roles in the biology of fungi. A considerable number of these polysaccharides has been described, differing in composition or linkage types. Their structure is similar in all species of a well-delimited genus, and teleomorphs and their corresponding anamorphs. Therefore, these polysaccharides have been used as chemotaxonomic markers at the genus level. Here we review cases where they have been found to resolve relationships around the genus level, and assess their phylogenetic informativeness in the delineation of taxa at family and higher ranks in the ascomycetes by comparison with molecular trees. Generally, the correlatio... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3559892 Thu, 01 Apr 2010 23:00:00 +0100 3559892 http://www.medworm.com/index.php?rid=3842898&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00218.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842898 Wed, 31 Mar 2010 23:00:00 +0100 3842898 http://www.medworm.com/index.php?rid=3842897&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00219.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842897 Wed, 31 Mar 2010 23:00:00 +0100 3842897 http://www.medworm.com/index.php?rid=3842896&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00221.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842896 Wed, 31 Mar 2010 23:00:00 +0100 3842896 http://www.medworm.com/index.php?rid=3842895&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00222.x (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3842895 Wed, 31 Mar 2010 23:00:00 +0100 3842895 http://www.medworm.com/index.php?rid=3424371&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00223.x In order to adapt to a variety of environmental conditions, bacteria bring about alterations in their protein expression profiles. This is mostly achieved by transcribing the required set of genes by deploying specific sigma factors. Since the amount of core RNA polymerase inside the cell is limited, the sigma factors have to compete against each other for association with core RNAP. During active growth, majority of the transcription activity is carried out by the house keeping sigma factor ([sigma]70 in E. coli, [sigma]A in B. subtilis), whose association with core RNAP is generally favoured because of its higher intracellular level and higher affinity to core RNAP. Increased levels of alternative sigma factors (e.g. E. coli[sigma]38) during stress or starvation help in competing for cor... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3424371 Tue, 30 Mar 2010 23:00:00 +0100 3424371 http://www.medworm.com/index.php?rid=3577042&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00223.x During active growth of Escherichia coli, majority of the transcriptional activity is carried out by the housekeeping sigma factor ([sigma]70), whose association with core RNAP is generally favoured because of its higher intracellular level and higher affinity to core RNAP. In order to facilitate transcription by alternative sigma factors during nutrient starvation, the bacterial cell uses multiple strategies by which the transcriptional ability of [sigma]70 is diminished in a reversible manner. The facilitators of shifting the balance in favour of alternative sigma factors happen to be as diverse as a small molecule (p)ppGpp (represents ppGpp or pppGpp), proteins (DksA, Rsd) and a species of RNA (6S RNA). Although 6S RNA and (p)ppGpp were known in literature for a long time, their role in... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3577042 Mon, 29 Mar 2010 23:00:00 +0100 3577042 http://www.medworm.com/index.php?rid=3490236&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00219.x Recent studies on the regulation of phage [phi]29 gene expression reveal new ways to accomplish the processes required for the orderly gene expression in prokaryotic systems. These studies revealed a novel DNA-binding domain in the phage main transcriptional regulator and the nature and dynamics of the multimeric DNA[ndash]protein complex responsible for the switch from early to late gene expression. This review describes the features of the regulatory mechanism that leads to the simultaneous activation and repression of transcription, and discusses it in the context of the role of the topological modification of the DNA carried out by two phage-encoded proteins working synergistically with the DNA. (Source: FEMS Microbiology Reviews) FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3490236 Wed, 17 Mar 2010 00:00:00 +0100 3490236 http://www.medworm.com/index.php?rid=3353986&cid=s_32048_77_f&fid=32048&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6976.2010.00216.x Gram-positive bacteria have developed elaborate mechanisms to control ammonium assimilation, at the levels of both transcription and enzyme activity. In this review, the common and specific mechanisms of nitrogen assimilation and regulation in Gram-positive bacteria are summarized and compared for the genera Bacillus, Clostridium, Streptomyces, Mycobacterium and Corynebacterium, with emphasis on the high G+C genera. Furthermore, the importance of nitrogen metabolism and control for the pathogenic lifestyle and virulence is discussed. In summary, the regulation of nitrogen metabolism in prokaryotes shows an impressive diversity. Virtually every phylum of bacteria evolved its own strategy to react to the changing conditions of nitrogen supply. Not only do the transcription factors differ bet... FEMS Microbiology Reviews journals http://www.medworm.com/rss/comments.php?id=3353986 Thu, 11 Mar 2010 00:00:00 +0100 3353986