ChromosomaThis is an RSS file. You can use it to subscribe to this data in your favourite RSS reader, such as GoogleReader, or to display this data on your own website or blog. Subscribe to this data using MyMedWorm.Subscribe to this data using GoogleReader.Subscribe to this data using Bloglines.Subscribe to this data using MyYahoo.

This page shows you the latest items in this publication.

Pages: 1 2 3 4 5 6

259 records returned

Chromosomal and telomeric reprogramming following ES-somatic cell fusionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Chromosomal and telomeric reprogramming was assessed in intraspecies hybrids obtained by fusion of embryonic stem (ES) cells and mouse embryonic fibroblasts. Evaluation of the ploidy of ES-somatic hybrids revealed that 21 of 59 clones had a tetraploid DNA profile while the remaining clones showed deviations from the expected profile of fusion between two diploid cells. Microsatellite polymerase chain reaction analysis of four of these clones demonstrated no random loss of somatic chromosome pairs in the ES-somatic cell hybrids. Pluripotential of ES-somatic hybrids was assessed by gene expression ana...
Source: Chromosoma - November 11, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Re-examination of siRNA specificity questions role of PICH and Tao1 in the spindle checkpoint and identifies Mad2 as a sensitive target for small RNAsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The DNA-dependent adenosine triphosphatase (ATPase) Plk1-interacting checkpoint helicase (PICH) has recently been implicated in spindle checkpoint (SAC) signaling (Baumann et al., Cell 128(1):101–114, 2007). Depletion of PICH by siRNA abolished the SAC and resulted in an apparently selective loss of Mad2 from kinetochores, suggesting a role for PICH in the regulation of the Mad1–Mad2 interaction. An apparent rescue of SAC functionality by overexpression of PICH in PICH-depleted cells initially seemed to confirm a role for PICH in the SAC. However, we have subsequently discovered that all PICH-di...
Source: Chromosoma - November 10, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

MRN and the race to the breakEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In all living cells, DNA is constantly threatened by both endogenous and exogenous agents. In order to protect genetic information, all cells have developed a sophisticated network of proteins, which constantly monitor genomic integrity. This network, termed the DNA damage response, senses and signals the presence of DNA damage to effect numerous biological responses, including DNA repair, transient cell cycle arrests (“checkpoints”) and apoptosis. The MRN complex (MRX in yeast), composed of Mre11, Rad50 and Nbs1 (Xrs2), is a key component of the immediate early response to DNA damage, involved ...
Source: Chromosoma - October 27, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Synaptonemal complex stability depends on repressive histone marks of the lateral element-associated repeat sequencesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The synaptonemal complex (SC) is the central key structure for meiosis in organisms undergoing sexual reproduction. During meiotic prophase I, homologous chromosomes exchange genetic information at the time they are attached to the lateral elements by specific DNA sequences. Most of these sequences, so far identified, consist of repeat DNA, which are subject to chromatin structural changes during meiotic prophase I. In this work, we addressed the effect of altering the chromatin structure of repeat DNA sequences mediating anchorage to the lateral elements of the SC. Administration of the histone dea...
Source: Chromosoma - October 9, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

SUMOylation is required for normal development of linear elements and wild-type meiotic recombination in Schizosaccharomyces pombeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In the fission yeast, Schizosaccharomyces pombe, synaptonemal complexes (SCs) are not formed during meiotic prophase. However, structures resembling the axial elements of SCs, the so-called linear elements (LinEs) appear. By in situ immunostaining, we found Pmt3 (S. pombe's SUMO protein) transiently along LinEs, suggesting that SUMOylation of some component(s) of LinEs occurs during meiosis. Mutation of the SUMO ligase Pli1 caused aberrant LinE formation and reduced genetic recombination indicating a role for SUMOylation of LinEs for the regulation of meiotic recombination. Western blot analysis of T...
Source: Chromosoma - September 16, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Divergence in centromere structure distinguishes related genomes in Coix lacryma-jobi and its wild relativeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Knowledge about the composition and structure of centromeres is critical for understanding how centromeres perform their functional roles. Here, we report the sequences of one centromere-associated bacterial artificial chromosome clone from a Coix lacryma-jobi library. Two Ty3/gypsy-class retrotransposons, centromeric retrotransposon of C. lacryma-jobi (CRC) and peri-centromeric retrotransposon of C. lacryma-jobi, and a (peri)centromere-specific tandem repeat with a unit length of 153 bp were identified. The CRC is highly homologous to centromere-specific retrotransposons reported in grass species...
Source: Chromosoma - September 16, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Solving the Dnmt2 enigmaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Dnmt2 is a member of the animal DNA methyltransferase family of enzymes. While the role of other Dnmt proteins has been extensively characterized, comparably little is known about Dnmt2. This is surprising because Dnmt2 is the most widely conserved Dnmt protein, with homologues in protists, plants, fungi, and animals. In this review, we discuss the evidence supporting the seemingly contradictory roles of Dnmt2 in both DNA and RNA methylation. New studies are uncovering the enzymatic mechanisms that mediate these activities and also provide first insights into the biological functions of Dnmt2. Lastl...
Source: Chromosoma - September 16, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Spatial organization of genes as a component of regulated expressionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The DNA of living cells is highly compacted. Inherent in this spatial constraint is the need for cells to organize individual genetic loci so as to facilitate orderly retrieval of information. Complex genetic regulatory mechanisms are crucial to all organisms, and it is becoming increasingly evident that spatial organization of genes is one very important mode of regulation for many groups of genes. In eukaryotic nuclei, it appears not only that DNA is organized in three-dimensional space but also that this organization is dynamic and interactive with the transcriptional state of the genes. Spatial ...
Source: Chromosoma - September 3, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

pRb, a local chromatin organizer with global possibilitiesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The retinoblastoma (pRb) family of proteins are well known for their tumor suppressor properties and for their ability to regulate transcription. The action of pRb family members correlates with the appearance of repressive chromatin marks at promoter regions of genes encoding key regulators of cell proliferation. Recent studies raise the possibility that pRb family members do not simply act by controlling the activity of individual promoters but that they may also function by promoting the more general organization of chromatin. In several contexts, pRb family members stimulate the compaction or co...
Source: Chromosoma - August 28, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

H2AX: functional roles and potential applicationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Upon DNA double-strand break (DSB) induction in mammals, the histone H2A variant, H2AX, becomes rapidly phosphorylated at serine 139. This modified form, termed γ-H2AX, is easily identified with antibodies and serves as a sensitive indicator of DNA DSB formation. This review focuses on the potential clinical applications of γ-H2AX detection in cancer and in response to other cellular stresses. In addition, the role of H2AX in homeostasis and disease will be discussed. Recent work indicates that γ-H2AX detection may become a powerful tool for monitoring genotoxic events associated with cancer deve...
Source: Chromosoma - August 25, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Partitioning the C. elegans genome by nucleosome modification, occupancy, and positioningEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract We have characterized two post-translational histone modifications in Caenorhabditis elegans on a genomic scale. Micrococcal nuclease digestion and immunoprecipitation were used to obtain distinct populations of single nucleosome cores, which were analyzed using massively parallel DNA sequencing to obtain positional and coverage maps. Two methylated histone H3 populations were chosen for comparison: H3K4 histone methylation (associated with active chromosomal regions) and H3K9 histone methylation (associated with inactivity). From analysis of the sequence data, we found nucleosome cores with these m...
Source: Chromosoma - August 25, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Histone3 variants in plantsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Regulation of chromatin activity by covalent histone modifications has been long recognized. Histones that constitute the nucleosome are encoded by large families of genes and display a strong degree of conservation. However, histone variants exist and it is becoming clear that they play important roles in genome regulation. While most studies of the role of histone3 (H3) variants in transcriptional control comes from animal models, emerging data in plants suggest functional conservation, although plant-specific roles are likely. We review these data and speculate on the biological significance of H...
Source: Chromosoma - August 23, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Macrosatellite epigenetics: the two faces of DXZ4 and D4Z4Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Almost half of the human genome consists of repetitive DNA. Understanding what role these elements have in setting up chromatin states that underlie gene and chromosome function in complex genomes is paramount. The function of some types of repetitive DNA is obvious by virtue of their location, such as the alphoid arrays that define active centromeres. However, there are many other types of repetitive DNA whose evolutionary origins and current roles in genome biology remain unknown. One type of repetitive DNA that falls into this class is the macrosatellites. The relevance of these sequences to dise...
Source: Chromosoma - August 19, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Localization and characteristics of DNA underreplication zone in the 75C region of intercalary heterochromatin in Drosophila melanogaster polytene chromosomesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In Drosophila polytene chromosomes, regions of intercalary heterochromatin are scattered throughout the euchromatic arms. Here, we present data on the first fine analysis of the individual intercalary heterochromatin region, 75C1-2, located in the 3L chromosome. By using electron microscopy, we demonstrated that this region appears as three closely adjacent condensed bands. Mapping of the region on the physical map by means of the chromosomal rearrangements with known breakpoints showed that the length of the region is about 445 kb. Although it seems that the SUUR protein binds to the whole 75C...
Source: Chromosoma - August 14, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Spatial link between nucleoli and expression of the Zac1 geneEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Eukaryotic genomes are highly organized within the cell nucleus. Genome organization not only implies the preferential positioning of genetic elements in the interphase nucleus but also the topographic distribution of biological processes. We have investigated the relationship between spatial organization and genome function in single cells. Myc, c-Met, Igf2r, Asb4, and Zac1 genes have the same radial distribution, but they are not positioned in close proximity with respect to each other. Three-dimensional mapping of their transcription sites uncovered a gene-specific pattern of relative positioning ...
Source: Chromosoma - July 31, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Meiotic behavior of aneuploid chromatin in mouse models of Down syndromeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Aneuploidy, which leads to unpaired chromosomal axes during meiosis, is frequently accompanied by infertility. We previously showed, using three mouse models of Down syndrome, that it is an extra chromosome, but not extra gene dose, that is associated with male infertility and virtual absence of post-meiotic gem cells. Here, we test the hypothesis that aneuploid segments are differentially modified and expressed during meiosis, depending on whether they are present as an extra chromosome or not. In all three models examined, the trisomic region lacks a pairing partner, but in one case, spermatocytes...
Source: Chromosoma - July 29, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

The amount of heterochromatic proteins in the egg is correlated with sex determination in Planococcus citri (Homoptera, Coccoidea)Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report here that egg cells of aged females show larger amounts of HP1 and Su(Var)3–9 than egg cells of young females. These data suggest that a determinant of sex may be the amount of maternally derived heterochromatic proteins. Content Type Journal ArticleCategory Research ArticleDOI 10.1007/s00412-009-0231-7Authors Giovanni Luigi Buglia, University of Rome “La Sapienza” Department of Genetics and Molecular Biology P.le A. Moro 5 00185 Rome ItalyDaniela Dionisi, University of Rome “La Sapienza” Department of Genetics and Molecular Biology P.le A. Moro 5 00185 Rome ItalyMarina Ferraro, University of Rom...
Source: Chromosoma - July 27, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Persistent mechanical linkage between sister chromatids throughout anaphaseEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In budding yeast, we have found that sister rDNA arrays marked with fluorescent probes can be visualized as two distinguishable strands during metaphase. Upon anaphase, these arm loci are drawn into the spindle, where they adopt a cruciform-like structure and stretch 2.5-fold as they migrate to the poles. Therefore, while sister rDNA arrays appear separated in metaphase, mechanical linkages between sister arm loci persist throughout anaphase in yeast, as shown in grasshopper spermatocytes (Paliulis and Nicklas 2004). These linkages are partially dependent on the protector of cohesin, SGO1. In anapha...
Source: Chromosoma - July 23, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Site-specifically phosphorylated forms of H1.5 and H1.2 localized at distinct regions of the nucleus are related to different processes during the cell cycleEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The cell cycle-associated phosphorylation of histone H1.5 is manifested as three discrete phosphorylated forms, occurring exclusively on Ser17, Ser172, and Ser188 during interphase. During late G2 and mitosis the up-phosphorylation occurs exclusively on threonine at either Thr137 or Thr154 to build the tetraphosphorylated forms of H1.5, whereas the pentaphosphorylated forms result from phosphorylation at Thr10. To determine the kinetic and spatial distribution of histone H1 phosphorylation within the nucleus of synchronized Hela cells we localized three distinct phosphorylation sites of histone subtyp...
Source: Chromosoma - July 18, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

At the right place at the right time: novel CENP-A binding proteins shed light on centromere assemblyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Centromeres, the chromosomal loci that form the sites of attachment for spindle microtubules during mitosis, are identified by a unique chromatin structure generated by nucleosomes containing the histone H3 variant CENP-A. The apparent epigenetic mode of centromere inheritance across mitotic and meiotic divisions has generated much interest in how CENP-A assembly occurs and how structurally divergent centromeric nucleosomes can specify the centromere complex. Although a substantial number of proteins have been implicated in centromere assembly, factors that can bind CENP-A specifically and deliver n...
Source: Chromosoma - July 10, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

The spatial repositioning of adipogenesis genes is correlated with their expression status in a porcine mesenchymal stem cell adipogenesis model systemEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we have examined the genome organization in interphase nuclei during adipogenesis, using the pig as a model organism. We hypothesized that changes in the gene expression profile and chromatin remodeling which occur during cellular differentiation would elicit repositioning of whole chromosomes, moving specific genes on them to different regions of the nucleus. We established an in vitro adipogenesis differentiation system using mesenchymal stem cells, derived from porcine bone marrow. The nuclear position of seven adipogenesis genes (PPARG, SREBF1, FABP4, CEBPA, CEBPB, CREB, and GATA2), two control gene...
Source: Chromosoma - July 9, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Zeste can facilitate long-range enhancer–promoter communication and insulator bypass in Drosophila melanogasterEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The looping model of enhancer–promoter interactions predicts that these specific long-range interactions are supported by a certain class of proteins. In particular, the Drosophila transcription factor Zeste was hypothesized to facilitate long-distance associations between enhancers and promoters. We have re-examined the role of Zeste in supporting long-range interactions between an enhancer and a promoter using the white gene as a model system. The results show that Zeste binds to the upstream white promoter region and the enhancer that is responsible for white activation in the eyes. We have confi...
Source: Chromosoma - July 6, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Rye B chromosomes are weakly transcribed and might alter the transcriptional activity of A chromosome sequencesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract B chromosomes (Bs) are dispensable components of the genomes of numerous species. To test whether the transcriptome of a host is influenced by Bs, we looked for differences in expression in response to additional Bs. Comparative complementary DNA amplified fragment length polymorphism experiments resulted in the identification of 16 putative B-chromosome-associated transcripts. This comprises 0.7% of the total transcript number and indicates a low activity of Bs. We also provide evidence that B chromosome influences in trans the transcription of A chromosome sequences. The B-specific transcribed seq...
Source: Chromosoma - July 6, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Synaptonemal complex assembly and H3K4Me3 demethylation determine DIDO3 localization in meiosisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Synapsis of homologous chromosomes is a key meiotic event, mediated by a large proteinaceous structure termed the synaptonemal complex. Here, we describe a role in meiosis for the murine death-inducer obliterator (Dido) gene. The Dido gene codes for three proteins that recognize trimethylated histone H3 lysine 4 through their amino-terminal plant homeodomain domain. DIDO3, the largest of the three isoforms, localizes to the central region of the synaptonemal complex in germ cells. DIDO3 follows the distribution of the central region protein SYCP1 in Sycp3−/− spermatocytes, which lack the axial el...
Source: Chromosoma - June 26, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Cohesin gene defects may impair sister chromatid alignment and genome stability in Arabidopsis thalianaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In contrast to yeast, plant interphase nuclei often display incomplete alignment (cohesion) along sister chromatid arms. Sister chromatid cohesion mediated by the multi-subunit cohesin complex is essential for correct chromosome segregation during nuclear divisions and for DNA recombination repair. The cohesin complex consists of the conserved proteins SMC1, SMC3, SCC3, and an α-kleisin subunit. Viable homozygous mutants could be selected for the Arabidopsis thaliana α-kleisins SYN1, SYN2, and SYN4, which can partially compensate each other. For the kleisin SYN3 and for the single-copy genes SMC1, ...
Source: Chromosoma - June 17, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Nuclear envelope-limited chromatin sheets (ELCS) and heterochromatin higher order structureEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The interphase nucleus and nuclear envelope can acquire a myriad of shapes in normal or pathological cell states. There exist a wide variety of indentations and invaginations, of protrusions and evaginations. It has been difficult to classify and name all of these nuclear shapes and, consequently, a barrier to understanding the biochemical and biophysical causes. This review focuses upon one type of nuclear envelope shape change, named “nuclear envelope-limited chromatin sheets” (ELCS), which appears to involve exaggerated nuclear envelope growth, carrying with it one or more layers of ∼30&nbs...
Source: Chromosoma - June 12, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

DNA methylation and methyl-CpG binding proteins: developmental requirements and functionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract DNA methylation is a major epigenetic modification in the genomes of higher eukaryotes. In vertebrates, DNA methylation occurs predominantly on the CpG dinucleotide, and approximately 60% to 90% of these dinucleotides are modified. Distinct DNA methylation patterns, which can vary between different tissues and developmental stages, exist on specific loci. Sites of DNA methylation are occupied by various proteins, including methyl-CpG binding domain (MBD) proteins which recruit the enzymatic machinery to establish silent chromatin. Mutations in the MBD family member MeCP2 are the cause of Rett syndro...
Source: Chromosoma - June 9, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Cohesin axis maturation and presence of RAD51 during first meiotic prophase in a true bugEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract We have analyzed in a true bug, Graphosoma italicum (Pentatomidae, Hemiptera), the temporal and functional relationships between recombination events, synapsis progression, and SMC1α and SMC3 cohesin axis maturation throughout the male first meiotic prophase. The localization of the histone variant histone H3 trimethylated at lysine 9 at chromosome ends has allowed us to determine the association of these heterochromatic domains through prophase I stages. Results highlighted that cohesins provide to be good markers for synapsis progression since the formation, morphology, and development of the SMC...
Source: Chromosoma - June 4, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

In memoriam—Crodowaldo PavanEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Content Type Journal ArticleCategory ObituaryDOI 10.1007/s00412-009-0217-5Authors Eduardo Gorab, Universidade de São Paulo Departamento de Genética e Biologia Evolutiva, Instituto de Biociências Rua do Matão 277, Cidade Universitária São Paulo São Paulo 05508-090 Brazil Journal ChromosomaOnline ISSN 1432-0886Print ISSN 0009-5915 (Source: Chromosoma)
Source: Chromosoma - May 29, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Epigenetic marks for chromosome imprinting during spermatogenesis in coccidsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The establishment of sex-specific epigenetic marks during gametogenesis is one of the key feature of genomic imprinting. By immunocytological analysis, we thoroughly characterized the chromatin remodeling events that take place during gametogenesis in the mealybug Planococcus citri, in which an entire haploid set of (imprinted) chromosomes undergoes facultative heterochromatinization in male embryos. Building on our previous work, we have investigated the interplay of several epigenetic marks in the regulation of this genome-wide phenomenon. We characterized the germline patterns of histone modifica...
Source: Chromosoma - May 21, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Molecular cloning and characterization of the germline-restricted chromosome sequence in the zebra finchEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The zebra finch (Taeniopygia guttata) germline-restricted chromosome (GRC) is the largest chromosome and has a unique system of transmission in germ cells. In the male, the GRC exists as a single heterochromatic chromosome in the germline and is eliminated from nuclei in late spermatogenesis. In the female, the GRC is bivalent and euchromatic and experiences recombination. These characteristics suggest a female-specific or female-beneficial function of the GRC. To shed light on the function of GRC, we cloned a portion of the GRC using random amplified polymorphic DNA–polymerase chain reaction and ...
Source: Chromosoma - May 19, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Constitutive heterochromatin: a surprising variety of expressed sequencesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The organization of chromosomes into euchromatin and heterochromatin is amongst the most important and enigmatic aspects of genome evolution. Constitutive heterochromatin is a basic yet still poorly understood component of eukaryotic chromosomes, and its molecular characterization by means of standard genomic approaches is intrinsically difficult. Although recent evidence indicates that the presence of transcribed genes in constitutive heterochromatin is a conserved trait that accompanies the evolution of eukaryotic genomes, the term heterochromatin is still considered by many as synonymous of gene ...
Source: Chromosoma - May 2, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

GAL4 induces transcriptionally active puff in the absence of dSAGA- and ATAC-specific chromatin acetylation in the Drosophila melanogaster polytene chromosomeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Puffs in the polytene chromosome of Drosophila melanogaster are characteristic of sites of high-level active transcription which can be observed directly under the microscope. We studied the dependence of puff formation on chromatin modifications at a site where a GAL4-inducible transgene is located in the 61C7 cytological region. Immunostaining of salivary gland polytene chromosomes indicated no increase of either dSAGA-specific histone H3 lysine 14, or ATAC-specific histone H4 lysine 5 and 12 acetylation in the puffed region. Nor did we observe increased levels of H4K8ac, H3K18ac, or H4K16ac in th...
Source: Chromosoma - May 2, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Cajal’s contribution to the knowledge of the neuronal cell nucleusEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In 1906, the Spanish neurobiologist Santiago Ramón y Cajal was awarded the Nobel Prize in Physiology or Medicine in recognition of his work on the structure of neurons and their connections. Cajal is commonly regarded as the father of modern neuroscience. What is less well known is that Cajal also had a great interest in intracellular neuronal structures and developed the reduced silver nitrate method for the study of neurofibrils (neurofilaments) and nuclear subcompartments. It was in 1903 that Cajal discovered the “accessory body” (“Cajal body”) and seven years later, published an article...
Source: Chromosoma - April 30, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Distinct acetylation of Trypanosoma cruzi histone H4 during cell cycle, parasite differentiation, and after DNA damageEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Histones of trypanosomes are quite divergent when compared to histones of most eukaryotes. Nevertheless, the histone H4 of Trypanosoma cruzi, the protozoan that causes Chagas’ disease, is acetylated in the N terminus at lysines 4, 10, and 14. Here, we investigated the cellular distribution of histone H4 containing each one of these posttranslational modifications by using specific antibodies. Histone H4 acetylated at lysine 4 (H4-K4ac) is found in the entire nuclear space preferentially at dense chromatin regions, excluding the nucleolus of replicating epimastigote forms of the parasite. In contra...
Source: Chromosoma - April 25, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Meiotic localization of Mre11 and Rad50 in wild type, spo11-1, and MRN complex mutants of Coprinus cinereusEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The Mre11-Rad50-Nbs1 (MRN) complex is required for numerous cellular processes that involve interactions with DNA double-strand breaks. For the majority of these processes, the MRN complex is thought to act as a unit, with each protein aiding the activity of the others. We have examined the relationship between Mre11 and Rad50 during meiosis in the basidiomycete Coprinus cinereus (Coprinopsis cinerea), investigating to what extent activities of Mre11 and Rad50 are interdependent. We showed that mre11-1 is epistatic to rad50-1 with respect to the time of meiotic arrest, indicating that Mre11 activity f...
Source: Chromosoma - April 25, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

An elegant miRror: microRNAs in stem cells, developmental timing and cancerEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract MicroRNAs (miRNAs) were first discovered in genetic screens for regulators of developmental timing in the stem-cell-like seam cell lineage in Caenorhabditis elegans. As members of the heterochronic pathway, the lin-4 and let-7 miRNAs are required in the seam cells for the correct progression of stage-specific events and to ensure that cell cycle exit and terminal differentiation occur at the correct time. Other heterochronic genes such as lin-28 and lin-41 are direct targets of the lin-4 and let-7 miRNAs. Recent findings on the functions of the let-7 and lin-4/mir-125 miRNA families and lin-28 and lin...
Source: Chromosoma - April 2, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

The Mi-2/NuRD complex associates with pericentromeric heterochromatin during S phase in rapidly proliferating lymphoid cellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Chromosomal replication results in the duplication not only of DNA sequence but also of the patterns of histone modification, DNA methylation, and nucleoprotein structure that constitute epigenetic information. Pericentromeric heterochromatin in human cells is characterized by unique patterns of histone and DNA modification. Here, we describe association of the Mi-2/NuRD complex with specific segments of pericentromeric heterochromatin consisting of Satellite II/III DNA located on human chromosomes 1, 9, and 16 in some but not all cell types. This association is linked in part to DNA replication and...
Source: Chromosoma - March 20, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Chromatin dynamics is correlated with replication timingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, a bio-computational approach is employed to simultaneously measure the translational motion of large populations of ChrD in the cell nucleus of living cells. Both movement and configurational changes are strikingly higher in early S-phase replicating ChrD compared to those that replicate in mid and late S-phase. The chromatin dynamics was not sensitive to transcription inhibition by α-amanitin but was significantly reduced by actinomycin D treatment. Since a majority of active genes replicate in early S-phase, our results suggest a correlation between levels of chromatin dynamics and chromatin poised f...
Source: Chromosoma - March 20, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

2C or not 2C: a closer look at cell nuclei and their DNA contentEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The life cycle of animals and plants involves changes in chromosome number (nuclear phase) and sometimes even the karyotype, and consequently the DNA content of a nuclear genome is not static in time. Thus, in order to interpret DNA content data, it is important that the status of the materials from which DNA content is estimated be precisely defined. The previously proposed distinction between “holoploid” (C) and “monoploid” (Cx) genome size covers the most frequent states of plant and animal nuclear genomes. However, restricting nomenclature to just C and Cx still leaves a number of unreso...
Source: Chromosoma - February 26, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Monoallelic gene expression in mammalsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Three systems of monoallelic gene expression in mammals are known, namely, X-chromosome inactivation, imprinting, and allelic exclusion. In all three systems, monoallelic expression is regulated epigenetically and is frequently directed by long non-coding RNAs (ncRNAs). This review briefs all three systems of monoallelic gene expression in mammals focusing on chromatin modifications, spatial chromosome organization in the nucleus, and the functioning of ncRNAs. Content Type Journal ArticleCategory ReviewDOI 10.1007/s00412-009-0206-8Authors Irina S. Zakharova, Russian Academy of Sciences Siberian...
Source: Chromosoma - February 26, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Relationship between incomplete synapsis and chiasma localizationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract One of the subjects within the meiotic field that has been actively investigated in the recent years is the temporal and functional relationships between meiotic recombination, cohesin loading and synaptonemal complex (SC) assembly. Although the study of meiotic mutants has shed some light, many questions remain to be answered. Here, we have studied this topic in the orthopteran Paratettix meridionalis, a species with telocentric chromosomes, which shows two unusual cytological features: pairing and synapsis of homologues during prophase I are restricted to the non-centromeric distal regions and ext...
Source: Chromosoma - February 24, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Two new chromodomain-containing proteins that associate with heterochromatin in Sciara coprophila chromosomesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report here the molecular and cytological characterization of two proteins, ScoHET1 and ScoHET2 (for Sciara coprophila heterochromatin), which associate to constitutive heterochromatin in the dipteran S. coprophila. Both proteins, ScoHET1 of 37 kDa and ScoHET2 of 44 kDa, display two chromodomain motifs that contain the conserved residues essential for the recognition of methylated histone H3 at lysine 9. We raised antibodies to analyze the chromosomal location of ScoHET1 and ScoHET2 in somatic and germline cells. In S. coprophila polytene chromosomes, both proteins associate to the pericentromeric regions an...
Source: Chromosoma - February 11, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Parental genomes mix in mule and human cell nucleiEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Whether chromosome sets inherited from father and mother occupy separate spaces in the cell nucleus is a question first asked over 110 years ago. Recently, the nuclear organization of the genome has come increasingly into focus as an important level of epigenetic regulation. In this context, it is indispensable to know whether or not parental genomes are spatially separated. Genome separation had been demonstrated for plant hybrids and for the early mammalian embryo. Conclusive studies for somatic mammalian cell nuclei are lacking because homologous chromosomes from the two parents cannot be di...
Source: Chromosoma - February 7, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Cloning and sequencing of the breakpoint regions of inversion 5g fixed in Drosophila buzzatiiEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we have characterized the breakpoint regions of inversion 5g, fixed in D. buzzatii and absent in Drosophila koepferae and other closely related species. A novel approach comprising four experimental steps was used. First, D. buzzatii BAC clones encompassing the breakpoints were identified and their ends sequenced. Then, breakpoint regions were mapped at high resolution in the Drosophila mojavensis genome sequence. Finally, breakpoint regions were isolated by polymerase chain reaction in D. buzzatii and D. koepferae and sequenced. Our aim was to shed light on the mechanism that generated inversion 5g and spe...
Source: Chromosoma - February 7, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

In memoriam—Evgueni AnanievEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Content Type Journal ArticleCategory ObituaryDOI 10.1007/s00412-009-0202-zAuthors Antoni Rafalski, DuPont Co./Pioneer Hi-Bred Wilmington DE 19807 USA Journal ChromosomaOnline ISSN 1432-0886Print ISSN 0009-5915 (Source: Chromosoma)
Source: Chromosoma - February 3, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Disruption of FEM1C-W gene in zebra finch: evolutionary insights on avian ZW genesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we analyzed the gene FEM1C which is highly conserved from Caenorhabditis elegans to higher vertebrates and interacts with the sex determining pathway in C. elegans. We found that FEM1C is located on the Z and W chromosome of zebra finches and probably other Passerine birds, but shows only Z linkage in other avian orders. In the zebra finch, FEM1C-W is degraded because of a point mutation and possibly because of loss of the first exon containing the start methionine. Thus, FEM1C-W appears to have degenerated or been lost from most bird species. FEM1C-Z is expressed in a cytoplasmic location in zebra finch f...
Source: Chromosoma - January 13, 2009 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

Changes in chromatin structure correlate with transcriptional activity of nucleolar rDNA in polytene chromosomesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Ribosomal DNA genes (rDNA) are found in tandem arrays of hundreds of repeated genes, but only a fraction of these genes are actively transcribed. The regulatory mechanism controlling the transition between active and inactive rDNA in higher eukaryotes is vital for cell survival. Here, we show that the nucleolus from Drosophila salivary gland cells contains two levels of chromatin organization reflecting differences in transcriptional activity: Decondensed chromatin is highly occupied with TATA-box-binding protein (TBP), phosphorylated H3S10, and acetylated H3K14, suggesting that rDNA in decondensed ...
Source: Chromosoma - December 10, 2008 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals

CAF-1 is required for efficient replication of euchromatic DNA in Drosophila larval endocycling cellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The endocycle constitutes an effective strategy for cell growth during development. In contrast to the mitotic cycle, it consists of multiple S-phases with no intervening mitosis and lacks a checkpoint ensuring the replication of the entire genome. Here, we report an essential requirement of chromatin assembly factor-1 (CAF-1) for Drosophila larval endocycles. This complex promotes histone H3–H4 deposition onto newly synthesised DNA in vitro. In metazoans, the depletion of its large subunit leads to the rapid accumulation of cells in S-phase. However, whether this slower S-phase progression result...
Source: Chromosoma - December 10, 2008 Category: Genetics & Stem Cells Tags: Chromosoma Source Type: journals