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Current topics in developmental biology. Preface.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19737639 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - September 10, 2009 Category: Biology Authors: Lecuit T Tags: Curr Top Dev Biol Source Type: journals

Intercellular adhesion in morphogenesis: molecular and biophysical considerations.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A major challenge in developmental biology is to understand how cellular processes that result from expression of the genetic program determine the material properties and shape transformations of tissues during morphogenesis. Cell/cell adhesion is critical in development, and it controls many aspects of tissue rearrangements that support morphogenesis. Intercellular adhesion not only allows cells to adhere together but also supports structure and function compartmentalization on the scale of cell assemblies, tissues, and organs. In metazoans, cadherins comprise a major class of cell/cell adhesion proteins. They form C...
Source: Current Topics in Developmental Biology - September 10, 2009 Category: Biology Authors: Borghi N, James Nelson W Tags: Curr Top Dev Biol Source Type: journals

Remodeling of the adherens junctions during morphogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Morphogenesis of epithelial tissues involves various forms of reshaping of cell layers, such as invagination or bending, convergent extension, and epithelial-mesenchymal transition. At the cellular level, these processes include changes in the shape, position, and assembly pattern of cells. During such morphogenetic processes, epithelial sheets in general maintain their multicellular architecture, implying that they must engage the mechanisms to change the spatial relationship with their neighbors without disrupting the junctions. A major junctional structure in epithelial tissues is the "adherens junction," which is c...
Source: Current Topics in Developmental Biology - September 10, 2009 Category: Biology Authors: Nishimura T, Takeichi M Tags: Curr Top Dev Biol Source Type: journals

How the cytoskeleton helps build the embryonic body plan: models of morphogenesis from Drosophila.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
One key challenge for cell and developmental biologists is to determine how the cytoskeletal toolkit is used to build embryonic tissues and organs. Here, we review recent progress in meeting this challenge, focusing on epithelial morphogenesis in the Drosophila embryo as a model. We outline how actin and microtubule networks are regulated by embryonic patterning systems, and how they affect cell shape, cell behavior, and cell-cell interactions to shape epithelial structures. We focus on the formation of the first epithelium at cellularization, the assembly of junctions, apical constriction of cells in the ventral furro...
Source: Current Topics in Developmental Biology - September 10, 2009 Category: Biology Authors: Harris TJ, Sawyer JK, Peifer M Tags: Curr Top Dev Biol Source Type: journals

Cell topology, geometry, and morphogenesis in proliferating epithelia.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Epithelia are sheets of tightly adherent cells that line both internal and external surfaces in a vast array of metazoans. During development, an intrinsic consequence of coupling tight adhesion with cellular proliferation is the emergence of an epithelial form characterized by a stereotyped distribution of polygonal cell shapes. Despite the near universality of this constraint on cell shape and tissue organization, very little is known about the possible implications of cell pattern geometry for mechanical properties of tissues or key biological processes, such as planar polarization, tissue remodeling, and cell divis...
Source: Current Topics in Developmental Biology - September 10, 2009 Category: Biology Authors: Gibson WT, Gibson MC Tags: Curr Top Dev Biol Source Type: journals

Principles of Drosophila eye differentiation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The Drosophila eye is one of nature's most beautiful structures and one of its most useful. It has emerged as a favored model for understanding the processes that direct cell fate specification, patterning, and morphogenesis. Though composed of thousands of cells, each fly eye is a simple repeating pattern of perhaps a dozen cell types arranged in a hexagonal array that optimizes coverage of the visual field. This simple structure combined with powerful genetic tools make the fly eye an ideal model to explore the relationships between local cell fate specification and global tissue patterning. In this chapter, I discus...
Source: Current Topics in Developmental Biology - September 10, 2009 Category: Biology Authors: Cagan R Tags: Curr Top Dev Biol Source Type: journals

Cellular and molecular mechanisms underlying the formation of biological tubes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Biological tubes are integral components of many organs. Based on their cellular organization, tubes can be divided into three types: multicellular, unicellular, and intracellular. The mechanisms by which these tubes form during development vary significantly, in many cases even for those sharing a similar final architecture. Here, we present recent advances in studying cellular and molecular aspects of tubulogenesis in different organisms. PMID: 19737645 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - September 10, 2009 Category: Biology Authors: Baer MM, Chanut-Delalande H, Affolter M Tags: Curr Top Dev Biol Source Type: journals

Convergence and extension movements during vertebrate gastrulation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
During vertebrate gastrulation, coordinated cell movements shape the basic body plan. Key components of gastrulation are convergence and extension (C&E) movements, which narrow and lengthen the embryonic tissues, respectively. The rates of C&E movements differ significantly according to the position and the stage of gastrulation. Here, we review the distinct cellular behaviors that define the spatial and temporal patterns of C&E movements, with the special emphasis on zebrafish. We also summarize the molecular regulation of these cellular behaviors and the interplay between different signaling pathways that...
Source: Current Topics in Developmental Biology - September 10, 2009 Category: Biology Authors: Yin C, Ciruna B, Solnica-Krezel L Tags: Curr Top Dev Biol Source Type: journals

Hox genes. Preface.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Authors: PMID: 19651299 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Tags: Curr Top Dev Biol Source Type: journals

The bithorax complex of Drosophila an exceptional Hox cluster.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In his 1978 seminal paper, Ed Lewis described a series of mutations that affect the segmental identities of the segments forming the posterior two-thirds of the Drosophila body plan. In each class of mutations, particular segments developed like copies of a more-anterior segment. Genetic mapping of the different classes of mutations led to the discovery that their arrangement along the chromosome paralleled the body segments they affect along the anteroposterior axis of the fly. As all these mutations mapped to the same cytological location, he named this chromosomal locus after its founding mutation. Thus the first ho...
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Authors: Maeda RK, Karch F Tags: Curr Top Dev Biol Source Type: journals

Evolution of the Hox gene complex from an evolutionary ground state.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this chapter, we consider the question of how the ordered clusters of Hox genes arose during evolution. Since ordered Hox clusters are found in all major superphyla, we have to assume that the Hox clusters arose before the Cambrian "explosion" giving rise to all of these taxa. Based on his studies of the bithorax complex (BX-C) in Drosophila Lewis considered the ground state to be the mesothoracic segment (T2) since the deletion of all of the genes of the BX-C leads to a transformation of all segments from T3 to A8/9 (the last abdominal segment) into T2 segments. We define the developmental ground state genetically,...
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Authors: Gehring WJ, Kloter U, Suga H Tags: Curr Top Dev Biol Source Type: journals

Hox specificity unique roles for cofactors and collaborators.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Hox proteins are well known for executing highly specific functions in vivo, but our understanding of the molecular mechanisms underlying gene regulation by these fascinating proteins has lagged behind. The premise of this review is that an understanding of gene regulation-by any transcription factor-requires the dissection of the cis-regulatory elements that they act upon. With this goal in mind, we review the concepts and ideas regarding gene regulation by Hox proteins and apply them to a curated list of directly regulated Hox cis-regulatory elements that have been validated in the literature. Our analysis of the Hox...
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Authors: Mann RS, Lelli KM, Joshi R Tags: Curr Top Dev Biol Source Type: journals

Hox genes and segmentation of the vertebrate hindbrain.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the vertebrate central nervous system, the hindbrain is an important center for coordinating motor activity, posture, equilibrium, sleep patterns, and essential unconscious functions, such as breathing rhythms and blood circulation. During development, the vertebrate hindbrain depends upon the process of segmentation or compartmentalization to create and organize regional properties essential for orchestrating its highly conserved functional roles. The process of segmentation in the hindbrain differs from that which functions in the paraxial mesoderm to generate somites and the axial skeleton. In the prospective hin...
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Authors: Tümpel S, Wiedemann LM, Krumlauf R Tags: Curr Top Dev Biol Source Type: journals

Hox genes in neural patterning and circuit formation in the mouse hindbrain.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The mammalian hindbrain is the seat of regulation of several vital functions that involve many of the organ systems of the body. Such functions are controlled through the activity of intricate arrays of neuronal circuits and connections. The establishment of ordered patterns of neuronal specification, migration, and axonal topographic connectivity during development is crucial to build such a complex network of circuits and functional connectivity in the mature hindbrain. The early development of the vertebrate hindbrain proceeds according to a fundamental metameric partitioning along the anteroposterior axis into cell...
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Authors: Narita Y, Rijli FM Tags: Curr Top Dev Biol Source Type: journals

Hox networks and the origins of motor neuron diversity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Motor behaviors are the primary means by which animals interact with their environment, forming the final output of most central nervous system (CNS) activity. The neural circuits that govern basic locomotor functions appear to be genetically hard wired and are comprised of discrete groups of neurons residing within the spinal cord. These local microcircuits coordinate simple reflexive behaviors in response to sensory stimuli and underlie the generation of rhythmic patterns of neural activity necessary for walking. In recent years there have been significant advances in understanding the genetic and molecular programs ...
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Authors: Dasen JS, Jessell TM Tags: Curr Top Dev Biol Source Type: journals

Establishment of Hox vertebral identities in the embryonic spine precursors.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The vertebrate spine exhibits two striking characteristics. The first one is the periodic arrangement of its elements-the vertebrae-along the anteroposterior axis. This segmented organization is the result of somitogenesis, which takes place during organogenesis. The segmentation machinery involves a molecular oscillator-the segmentation clock-which delivers a periodic signal controlling somite production. During embryonic axis elongation, this signal is displaced posteriorly by a system of traveling signaling gradients-the wavefront-which depends on the Wnt, FGF, and retinoic acid pathways. The other characteristic fe...
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Authors: Iimura T, Denans N, Pourquié O Tags: Curr Top Dev Biol Source Type: journals

Hox, Cdx, and anteroposterior patterning in the mouse embryo.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cdx and Hox gene families descend from the same ProtoHox cluster, already present in the common ancestors of bilaterians and cnidarians, and thought to act by providing anteroposterior (A-P) positional identity to axial tissues in all bilaterians. Mouse Cdx and Hox genes still exhibit common features in their early expression and function. The initiation and early shaping of Hox and Cdx transcriptional domains in mouse embryos are very similar, in keeping with their common involvement in conveying A-P information to the nascent tissues during embryonic axial elongation. Considerations of the impact on axial patterning ...
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Authors: Young T, Deschamps J Tags: Curr Top Dev Biol Source Type: journals

Hox genes and vertebrate axial pattern.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The axial skeleton in all vertebrates is comprised of similar structures that extend from anterior to posterior along the body axis: the occipital skull bones, cervical, thoracic, lumbar, sacral and caudal vertebrae. Despite significant changes in the number and size of these elements during vertebrate evolution, the basic character of these anatomical elements, as well as the order in which they appear, has remained strikingly similar. Extensive expression analysis, classic embryology experiments in chick and targeted loss-of-function mutant analyses in mice have clearly demonstrated that Hox genes are key regulators ...
Source: Current Topics in Developmental Biology - August 6, 2009 Category: Biology Authors: Wellik DM Tags: Curr Top Dev Biol Source Type: journals

Current topics in developmental biology. Evolution and development. Preface.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19361686 [PubMed - indexed for MEDLINE] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Jeffery WR Tags: Curr Top Dev Biol Source Type: journals

Chapter 1. Gene regulatory networks in neural crest development and evolution.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The neural crest is a multipotent migratory embryonic cell population that is present in all vertebrates, but missing from basal chordates. In this chapter, we discuss recent work in amphioxus, ascidians, lamprey, and gnathostomes that reflects the current state of knowledge of the evolutionary origin of this fascinating cell population. We summarize recent evidence for the ongoing diversification of the neural crest in several vertebrate species, with particular reference to studies in nontraditional vertebrate model organisms. PMID: 19361687 [PubMed - indexed for MEDLINE] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Nikitina N, Sauka-Spengler T, Bronner-Fraser M Tags: Curr Top Dev Biol Source Type: journals

Chapter 2. Evolution of vertebrate cartilage development.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Major advances in the molecular genetics, paleobiology, and the evolutionary developmental biology of vertebrate skeletogenesis have improved our understanding of the early evolution and development of the vertebrate skeleton. These studies have involved genetic analysis of model organisms, human genetics, comparative developmental studies of basal vertebrates and nonvertebrate chordates, and both cladistic and histological analyses of fossil vertebrates. Integration of these studies has led to renaissance in the area of skeletal development and evolution. Among the major findings that have emerged is the discovery of ...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Zhang G, Eames BF, Cohn MJ Tags: Curr Top Dev Biol Source Type: journals

Chapter 3. Caenorhabditis nematodes as a model for the adaptive evolution of germ cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A number of major adaptations in animals have been mediated by alteration of germ cells and their immediate derivatives, the gametes. Here, several such cases are discussed, including examples from echinoderms, vertebrates, insects, and nematodes. A feature of germ cells that make their development (and hence evolution) distinct from the soma is the prominent role played by posttranscriptional controls of mRNA translation in the regulation of proliferation and differentiation. This presents a number of special challenges for investigation of the evolution of germline development. Caenorhabditis nematodes represent a pa...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Haag ES Tags: Curr Top Dev Biol Source Type: journals

Chapter 4. New model systems for the study of developmental evolution in plants.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The number of genetically tractable plant model systems is rapidly increasing, thanks to the decreasing cost of sequencing and the wide amenability of plants to stable transformation and other functional approaches. In this chapter, I discuss emerging model systems from throughout the land plant phylogeny and consider how their unique attributes are contributing to our understanding of development, evolution, and ecology. These new models are being developed using two distinct strategies: in some cases, they are selected because of their close relationship to the established models, while in others, they are chosen wit...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Kramer EM Tags: Curr Top Dev Biol Source Type: journals

Chapter 5. Patterning the spiralian embryo: insights from Ilyanassa.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The spiralian developmental program is a highly conserved mode of early development that is characterized by regularities in cleavage pattern, fate map, and larval morphology. It is found in a number of animal phyla, and was likely present in the last common ancestor of the large superphylum Lophotrochozoa. Despite this key position for understanding the evolution of development in animals, and the intrinsic advantages for using spiralian embryos to study embryonic development and asymmetric cell division, very little is known about the molecular mechanisms of spiralian embryogenesis. The snail Ilyanassa has typical sp...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Lambert JD Tags: Curr Top Dev Biol Source Type: journals

Chapter 6. The origin and diversification of complex traits through micro- and macroevolution of development: insights from horned beetles.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Understanding how development and ecology shape organismal evolution is a central goal of evolutionary developmental biology. This chapter highlights a class of traits and organisms that are emerging as new models in evo-devo and eco-devo research: beetle horns and horned beetles. Horned beetles are morphologically diverse, ecologically rich, and developmentally and genetically increasingly accessible. Recent studies have begun to take advantage of these attributes and are starting to link the microevolution of horned beetle development to the macroevolution of novel features, and to identify the genetic, developmental...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Moczek AP Tags: Curr Top Dev Biol Source Type: journals

Chapter 7. Axis formation and the rapid evolutionary transformation of larval form.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Marine invertebrate embryos and larvae are diverse and can evolve rapidly, providing a link between early developmental and evolutionary mechanisms. We here discuss the role of evolutionary changes in axis formation, which is a crucial part of the patterning of marine embryos and larvae. We focus on sea urchin embryos, where axial features are well defined and subject to active current investigation. The genetic control of processes of formation of the three axial systems, animal-vegetal, dorsal-ventral, and left-right, is becoming established for species that undergo development via the feeding pluteus larva. These sp...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Raff RA, Snoke Smith M Tags: Curr Top Dev Biol Source Type: journals

Chapter 8. Evolution and development in the cavefish Astyanax.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The teleost Astyanax mexicanus is a single species consisting of two radically different forms: a sighted pigmented surface-dwelling form (surface fish) and a blind depigmented cave-dwelling form (cavefish). The two forms of Astyanax have favorable attributes, including descent from a common ancestor, ease of laboratory culture, and the ability to perform genetic analysis, permitting their use as a model system to explore questions in evolution and development. Here, we review current research on the molecular, cellular, and developmental mechanisms underlying the loss of eyes and pigmentation in Astyanax cavefish. Alt...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Jeffery WR Tags: Curr Top Dev Biol Source Type: journals

Theoretical models of neural circuit development.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Proper wiring up of the nervous system is critical to the development of organisms capable of complex and adaptable behaviors. Besides the many experimental advances in determining the cellular and molecular machinery that carries out this remarkable task precisely and robustly, theoretical approaches have also proven to be useful tools in analyzing this machinery. A quantitative understanding of these processes can allow us to make predictions, test hypotheses, and appraise established concepts in a new light. Three areas that have been fruitful in this regard are axon guidance, retinotectal mapping, and activity-depe...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Simpson HD, Mortimer D, Goodhill GJ Tags: Curr Top Dev Biol Source Type: journals

The developmental integration of cortical interneurons into a functional network.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The central goal of this manuscript is to survey our present knowledge of how cortical interneuron subtypes are generated. To achieve this, we will first define what is meant by subtype diversity. To this end, we begin by considering the mature properties that differentiate between the different populations of cortical interneurons. This requires us to address the difficulties involved in determining which characteristics allow particular interneurons to be assigned to distinct subclasses. Having grappled with this thorny issue, we will then proceed to review the progressive events in development involved in the genera...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Batista-Brito R, Fishell G Tags: Curr Top Dev Biol Source Type: journals

Transcriptional networks in the early development of sensory-motor circuits.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The emergence of coordinated locomotor behaviors in vertebrates relies on the establishment of selective connections between discrete populations of neurons present in the spinal cord and peripheral nervous system. The assembly of the circuits necessary for movement presumably requires the generation of many unique cell types to accommodate the intricate connections between motor neurons, sensory neurons, interneurons, and muscle. The specification of diverse neuronal subtypes is mediated largely through networks of transcription factors that operate within progenitor and postmitotic cells. Selective patterns of transc...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Dasen JS Tags: Curr Top Dev Biol Source Type: journals

Development of neural circuits in the adult hippocampus.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The hippocampal formation is widely studied in part because of its distinct and highly laminar organization as well as its demonstrated fundamental role in learning and memory. The dentate gyrus of the hippocampal formation is one of two recognized brain regions that continually generate new neurons in adulthood. In this chapter, we review the basic structure of hippocampal cellular components and circuitry, the properties of stem cells and their progeny in the dentate gyrus, and the known mechanisms and timing of their maturation and integration into the adult circuitry. We also address the functional implication of n...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Li Y, Mu Y, Gage FH Tags: Curr Top Dev Biol Source Type: journals

Looking beyond development: maintaining nervous system architecture.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Neuronal circuitries established in development must persist throughout life. This poses a serious challenge to the structural integrity of an embryonically patterned nervous system as an animal dramatically increases its size postnatally, remodels parts of its anatomy, and incorporates new neurons. In addition, body movements, injury, and ageing generate physical stress on the nervous system. Specific molecular pathways maintain intrinsic properties of neurons in the mature nervous system. Other factors ensure that the overall organization of entire neuronal ensembles into ganglia and fascicles is appropriately mainta...
Source: Current Topics in Developmental Biology - June 28, 2009 Category: Biology Authors: Bénard C, Hobert O Tags: Curr Top Dev Biol Source Type: journals

Red cell development. Preface.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 18282514 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - April 10, 2008 Category: Biology Authors: Bieker JJ Tags: Curr Top Dev Biol Source Type: journals

Preface.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 18282514 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - February 20, 2008 Category: Biology Authors: Bieker JJ Tags: Curr Top Dev Biol Source Type: journals

Chapter 1 ontogeny of erythropoiesis in the Mammalian embryo.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Red cells are required not only for adult well-being but also for survival and growth of the mammalian embryo beyond early postimplantation stages of development. The embryo's first "primitive" erythroid cells, derived from a transient wave of committed progenitors, emerge from the yolk sac as immature precursors and differentiate as a semisynchronous cohort in the bloodstream. Surprisingly, this maturational process in the mammalian embryo is characterized by globin gene switching and ultimately by enucleation. The yolk sac also synthesizes a second transient wave of "definitive" erythroid progenitors that enter the b...
Source: Current Topics in Developmental Biology - February 20, 2008 Category: Biology Authors: McGrath K, Palis J Tags: Curr Top Dev Biol Source Type: journals

Chapter 2 the erythroblastic island.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Erythroblastic islands are specialized microenvironmental compartments within which definitive mammalian erythroblasts proliferate and differentiate. These islands consist of a central macrophage that extends cytoplasmic protrusions to a ring of surrounding erythroblasts. The interaction of cells within the erythroblastic island is essential for both early and late stages of erythroid maturation. It has been proposed that early in erythroid maturation the macrophages provide nutrients, proliferative and survival signals to the erythroblasts, and phagocytose extruded erythroblast nuclei at the conclusion of erythroid ma...
Source: Current Topics in Developmental Biology - February 20, 2008 Category: Biology Authors: Manwani D, Bieker JJ Tags: Curr Top Dev Biol Source Type: journals

Chapter 3 epigenetic control of complex Loci during erythropoiesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Epigenetic mechanisms involving dynamic changes in posttranslational histone modifications commonly control gene transcription and therefore the execution of all cellular differentiation programs. The differentiation of hematopoietic stem cells into specific progenitor cells and the diverse blood cell types represents a particularly powerful system for the study of epigenetic mechanisms. The hematopoietic system allows one to define mechanisms underlying the establishment and regulation of histone modification patterns covering entire genes and/or chromosomes at distinct stages of differentiation. This chapter reviews ...
Source: Current Topics in Developmental Biology - February 20, 2008 Category: Biology Authors: Wozniak RJ, Bresnick EH Tags: Curr Top Dev Biol Source Type: journals

Chapter 4 the role of the epigenetic signal, DNA methylation, in gene regulation during erythroid development.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The sequence complexity of the known vertebrate genomes alone is insufficient to account for the diversity between individuals of a species. Although our knowledge of vertebrate biology has evolved substantially with the growing compilation of sequenced genomes, understanding the temporal and spatial regulation of genes remains fundamental to fully exploiting this information. The importance of epigenetic factors in gene regulation was first hypothesized decades ago when biologists posited that methylation of DNA could heritably alter gene expression [Holliday and Pugh, 1975. Science187(4173), 226-232; Riggs, 1975. Cyt...
Source: Current Topics in Developmental Biology - February 20, 2008 Category: Biology Authors: Ginder GD, Gnanapragasam MN, Mian OY Tags: Curr Top Dev Biol Source Type: journals

Chapter 5 three-dimensional organization of gene expression in erythroid cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The history of globin research is marked by a series of contributions seminal to our understanding of the genome, its function, and its relation to disease. For example, based on studies on hemoglobinopathies, it was understood that gene expression can be under the control of DNA elements that locate away from the genes on the linear chromosome template. Recent technological developments have allowed the demonstration that these regulatory DNA elements communicate with the genes through physical interaction, which loops out the intervening chromatin fiber. Subsequent studies showed that the spatial organization of the ...
Source: Current Topics in Developmental Biology - February 20, 2008 Category: Biology Authors: de Laat W, Klous P, Kooren J, Noordermeer D, Palstra RJ, Simonis M, Splinter E, Grosveld F Tags: Curr Top Dev Biol Source Type: journals

Chapter 6 iron homeostasis and erythropoiesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Erythrocytes require iron to perform their duty as oxygen carriers. Mammals have evolved a mechanism to maintain systemic iron within an optimal range that fosters erythroid development and function while satisfying other body iron needs. This chapter reviews erythroid iron uptake and utilization as well as systemic factors that influence iron availability. One of these factors is hepcidin, a circulating peptide hormone that maintains iron homeostasis. Elevated levels of hepcidin in the bloodstream effectively shut off iron absorption by disabling the iron exporter ferroportin. Conversely, low levels of circulating hep...
Source: Current Topics in Developmental Biology - February 20, 2008 Category: Biology Authors: Wrighting DM, Andrews NC Tags: Curr Top Dev Biol Source Type: journals

Chapter 7 effects of nitric oxide on red blood cell development and phenotype.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Nitric oxide (NO) is a diffusible free radical generated primarily by NO synthases (NOS), isoenzymes that convert the l-arginine and molecular oxygen to citrulline and NO in cells. Endothelial cells as well as macrophages, components of hematopoietic microenvironment and potent NO producers, play an active role in the modulation of human hematopoietic cell growth and differentiation. A role of NO in erythroid cell differentiation has been postulated based on demonstration that NO inhibits growth, differentiation, and hemoglobinization of erythroid primary cells. Endothelial NOS (eNOS) mRNA and protein levels, as well a...
Source: Current Topics in Developmental Biology - February 20, 2008 Category: Biology Authors: Cokić VP, Schechter AN Tags: Curr Top Dev Biol Source Type: journals

Chapter 8 diamond blackfan anemia: a disorder of red blood cell development.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Diamond Blackfan anemia (DBA) is an inherited hypoplastic anemia that typically presents in the first year of life. The genes identified to date that are mutated in DBA encode ribosomal proteins, and in these cases ribosomal protein haploinsufficiency gives rise to the disease. The developmental timing of DBA presentation suggests that the changes in red blood cell production that occur around the time of birth trigger a pathophysiological mechanism, likely linked to defective ribosome synthesis, which precipitates the hematopoietic phenotype. Variable presentation of other clinical phenotypes in DBA patients indicates...
Source: Current Topics in Developmental Biology - February 20, 2008 Category: Biology Authors: Ellis SR, Lipton JM Tags: Curr Top Dev Biol Source Type: journals

Multiscale modeling of developmental systems. Introduction.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 18023722 [PubMed - indexed for MEDLINE] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - January 31, 2008 Category: Biology Authors: Schnell S, Maini PK, Newman SA, Newman TJ Tags: Curr Top Dev Biol Source Type: journals

Introduction.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 18023722 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - November 21, 2007 Category: Biology Authors: Schnell S, Maini PK, Newman SA, Newman TJ Tags: Curr Top Dev Biol Source Type: journals

1 models of biological pattern formation: from elementary steps to the organization of embryonic axes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
An inroad into an understanding of the complex molecular interactions on which development is based can be achieved by uncovering the minimum requirements that describe elementary steps and their linkage. Organizing regions and other signaling centers can be generated by reactions that involve local self-enhancement coupled to antagonistic reactions of longer range. More complex patterns result from a chaining of such reactions in which one pattern generates the prerequisites for the next. Patterning along the single axis of radial symmetric animals including the small freshwater polyp hydra can be explained in this wa...
Source: Current Topics in Developmental Biology - November 21, 2007 Category: Biology Authors: Meinhardt H Tags: Curr Top Dev Biol Source Type: journals

2 Robustness of Embryonic Spatial Patterning in Drosophila melanogaster.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 18023724 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - November 21, 2007 Category: Biology Authors: Umulis D, O'Connor MB, Othmer HG Tags: Curr Top Dev Biol Source Type: journals

3 integrating morphogenesis with underlying mechanics and cell biology.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We describe processes operating in the embryo from whole embryo scale, the tissue-scale, to the cellular and extracellular matrix scale. We focus on describing cells, their behaviors and the unique microenvironments they traverse during gastrulation and discuss the role of tissue mechanics in these processes. PMID: 18023725 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - November 21, 2007 Category: Biology Authors: Davidson LA Tags: Curr Top Dev Biol Source Type: journals

4 the mechanisms underlying primitive streak formation in the chick embryo.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Formation of the primitive streak is one of the key events in the early development of amniote embryos. The streak is the site where during gastrulation the mesendoderm cells ingress to take up their correct topographical positions in the embryo. The process of streak formation can be conveniently observed in the chick embryo, where the streak forms as an accumulation of cells in the epiblast in the posterior pole of the embryo and extends subsequently in anterior direction until it covers 80% of the epiblast. A prerequisite for streak formation is the differentiation of mesoderm, which is induced in the epiblast at th...
Source: Current Topics in Developmental Biology - November 21, 2007 Category: Biology Authors: Chuai M, Weijer CJ Tags: Curr Top Dev Biol Source Type: journals

5 grid-free models of multicellular systems, with an application to large-scale vortices accompanying primitive streak formation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper is comprised of two parts. In the first we provide a brief overview of grid-free methods for modeling multicellular systems. We focus on an approach based on Langevin equations, in which inertia is ignored, and stochastic effects on cell motion are included. The discussion starts with simpler models, in which cells are modeled as adhesive spheres. We then turn to more sophisticated approaches in which nontrivial cell shape is accommodated, including the recently introduced Subcellular Element Model, in which each cell is described as a cluster of adhesively coupled over-damped subcellular elements, represent...
Source: Current Topics in Developmental Biology - November 21, 2007 Category: Biology Authors: Newman TJ Tags: Curr Top Dev Biol Source Type: journals

6 mathematical models for somite formation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Somitogenesis is the process of division of the anterior-posterior vertebrate embryonic axis into similar morphological units known as somites. These segments generate the prepattern which guides formation of the vertebrae, ribs and other associated features of the body trunk. In this work, we review and discuss a series of mathematical models which account for different stages of somite formation. We begin by presenting current experimental information and mechanisms explaining somite formation, highlighting features which will be included in the models. For each model we outline the mathematical basis, show results o...
Source: Current Topics in Developmental Biology - November 21, 2007 Category: Biology Authors: Baker RE, Schnell S, Maini PK Tags: Curr Top Dev Biol Source Type: journals