RESUMO
A mechanistic connection between aging and development is largely unexplored. Through profiling age-related chromatin and transcriptional changes across 22 murine cell types, analyzed alongside previous mouse and human organismal maturation datasets, we uncovered a transcription factor binding site (TFBS) signature common to both processes. Early-life candidate cis-regulatory elements (cCREs), progressively losing accessibility during maturation and aging, are enriched for cell-type identity TFBSs. Conversely, cCREs gaining accessibility throughout life have a lower abundance of cell identity TFBSs but elevated activator protein 1 (AP-1) levels. We implicate TF redistribution toward these AP-1 TFBS-rich cCREs, in synergy with mild downregulation of cell identity TFs, as driving early-life cCRE accessibility loss and altering developmental and metabolic gene expression. Such remodeling can be triggered by elevating AP-1 or depleting repressive H3K27me3. We propose that AP-1-linked chromatin opening drives organismal maturation by disrupting cell identity TFBS-rich cCREs, thereby reprogramming transcriptome and cell function, a mechanism hijacked in aging through ongoing chromatin opening.
Assuntos
Envelhecimento , Cromatina , Fator de Transcrição AP-1 , Animais , Envelhecimento/genética , Envelhecimento/metabolismo , Fator de Transcrição AP-1/metabolismo , Cromatina/metabolismo , Camundongos , Humanos , Camundongos Endogâmicos C57BL , Sítios de LigaçãoRESUMO
The Wnt/ß-catenin signaling pathway is highly conserved throughout evolution, playing crucial roles in several developmental and pathological processes. Wnt ligands can act at a considerable distance from their sources and it is therefore necessary to examine not only the Wnt-producing but also the Wnt-receiving cells and tissues to fully appreciate the many functions of this pathway. To monitor Wnt activity, multiple tools have been designed which consist of multimerized Wnt signaling response elements (TCF/LEF binding sites) driving the expression of fluorescent reporter proteins (e.g. GFP, RFP) or of LacZ. The high stability of those reporters leads to a considerable accumulation in cells activating the pathway, thereby making them easily detectable. However, this makes them unsuitable to follow temporal changes of the pathway's activity during dynamic biological events. Even though fluorescent transcriptional reporters can be destabilized to shorten their half-lives, this dramatically reduces signal intensities, particularly when applied in vivo. To alleviate these issues, we developed two transgenic quail lines in which high copy number (12× or 16×) of the TCF/LEF binding sites drive the expression of destabilized GFP variants. Translational enhancer sequences derived from viral mRNAs were used to increase signal intensity and specificity. This resulted in transgenic lines efficient for the characterization of TCF/ß-catenin transcriptional dynamic activities during embryogenesis, including using in vivo imaging. Our analyses demonstrate the use of this transcriptional reporter to unveil novel aspects of Wnt signaling, thus opening new routes of investigation into the role of this pathway during amniote embryonic development.
Assuntos
Fatores de Transcrição TCF , beta Catenina , Animais , Animais Geneticamente Modificados , Desenvolvimento Embrionário , Codorniz/metabolismo , Fatores de Transcrição TCF/metabolismo , Proteínas Wnt/metabolismo , Via de Sinalização Wnt , beta Catenina/genética , beta Catenina/metabolismoRESUMO
Fusion of nascent myoblasts to pre-existing myofibres is critical for skeletal muscle growth and repair. The vast majority of molecules known to regulate myoblast fusion are necessary in this process. Here, we uncover, through high-throughput in vitro assays and in vivo studies in the chicken embryo, that TGFß (SMAD2/3-dependent) signalling acts specifically and uniquely as a molecular brake on muscle fusion. While constitutive activation of the pathway arrests fusion, its inhibition leads to a striking over-fusion phenotype. This dynamic control of TGFß signalling in the embryonic muscle relies on a receptor complementation mechanism, prompted by the merging of myoblasts with myofibres, each carrying one component of the heterodimer receptor complex. The competence of myofibres to fuse is likely restored through endocytic degradation of activated receptors. Altogether, this study shows that muscle fusion relies on TGFß signalling to regulate its pace.
Assuntos
Fibras Musculares Esqueléticas/efeitos dos fármacos , Mioblastos/citologia , Mioblastos/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Animais , Comunicação Celular/fisiologia , Diferenciação Celular/fisiologia , Fusão Celular , Galinhas , Imuno-Histoquímica , Hibridização In Situ , Camundongos , Fibras Musculares Esqueléticas/metabolismo , Miofibrilas/metabolismo , Transdução de Sinais/fisiologiaRESUMO
Skeletal muscle regenerates through the activation of resident stem cells. Termed satellite cells, these normally quiescent cells are induced to proliferate by wound-derived signals1. Identifying the source and nature of these cues has been hampered by an inability to visualize the complex cell interactions that occur within the wound. Here we use muscle injury models in zebrafish to systematically capture the interactions between satellite cells and the innate immune system after injury, in real time, throughout the repair process. This analysis revealed that a specific subset of macrophages 'dwell' within the injury, establishing a transient but obligate niche for stem cell proliferation. Single-cell profiling identified proliferative signals that are secreted by dwelling macrophages, which include the cytokine nicotinamide phosphoribosyltransferase (Nampt, which is also known as visfatin or PBEF in humans). Nampt secretion from the macrophage niche is required for muscle regeneration, acting through the C-C motif chemokine receptor type 5 (Ccr5), which is expressed on muscle stem cells. This analysis shows that in addition to their ability to modulate the immune response, specific macrophage populations also provide a transient stem-cell-activating niche, directly supplying proliferation-inducing cues that govern the repair process that is mediated by muscle stem cells. This study demonstrates that macrophage-derived niche signals for muscle stem cells, such as NAMPT, can be applied as new therapeutic modalities for skeletal muscle injury and disease.
Assuntos
Macrófagos/metabolismo , Músculo Esquelético/citologia , Músculo Esquelético/lesões , Mioblastos/citologia , Nicotinamida Fosforribosiltransferase/metabolismo , Nicho de Células-Tronco , Peixe-Zebra/metabolismo , Animais , Proliferação de Células , Modelos Animais de Doenças , Humanos , Macrófagos/citologia , Masculino , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Mioblastos/metabolismo , Nicotinamida Fosforribosiltransferase/genética , Fator de Transcrição PAX7/metabolismo , RNA-Seq , Receptores CCR5/genética , Receptores CCR5/metabolismo , Regeneração/fisiologia , Análise de Célula Única , Peixe-Zebra/imunologiaRESUMO
Due to its amenability to manipulations, to live observation and its striking similarities to mammals, the chicken embryo has been one of the major animal models in biomedical research. Although it is technically possible to genome-edit the chicken, its long generation time (6 months to sexual maturity) makes it an impractical lab model and has prevented it widespread use in research. The Japanese quail (Coturnix coturnix japonica) is an attractive alternative, very similar to the chicken, but with the decisive asset of a much shorter generation time (1.5 months). In recent years, transgenic quail lines have been described. Most of them were generated using replication-deficient lentiviruses, a technique that presents diverse limitations. Here, we introduce a novel technology to perform transgenesis in quail, based on the in vivo transfection of plasmids in circulating Primordial Germ Cells (PGCs). This technique is simple, efficient and allows using the infinite variety of genome engineering approaches developed in other models. Furthermore, we present a website centralizing quail genomic and technological information to facilitate the design of genome-editing strategies, showcase the past and future transgenic quail lines and foster collaborative work within the avian community.
Assuntos
Coturnix/genética , Técnicas de Transferência de Genes , Animais , Animais Geneticamente Modificados/genética , Animais Geneticamente Modificados/crescimento & desenvolvimento , Coturnix/crescimento & desenvolvimento , Feminino , Masculino , Plasmídeos/genética , Transfecção , NavegadorRESUMO
Striated muscle is the most abundant tissue in the body of vertebrates and it forms, together with the skeleton, the locomotory system required both for movement and the creation of the specific body shape of a species. Research on the embryonic development of muscles has a long tradition both in classical embryology and in molecular developmental biology. While the gene networks regulating muscle development have been discovered mostly in the mouse through genetics, our knowledge on cell lineages, muscle morphogenesis and tissue interactions regulating their formation is to a large extent based on the use of the avian model. This review highlights present knowledge of the development of skeletal muscle in vertebrate embryos. Special focus will be placed on the contributions from chicken and quail embryo model systems.
Assuntos
Embrião de Galinha , Desenvolvimento Embrionário , Desenvolvimento Muscular/fisiologia , Animais , Diferenciação Celular/fisiologia , Linhagem da Célula , Galinhas , Eletroporação , Mesoderma/fisiologia , Camundongos , Morfogênese , Codorniz/embriologia , Transdução de Sinais , Somitos , Células-TroncoRESUMO
The migration of limb myogenic precursors from limb level somites to their ultimate site of differentiation in the limb is a paradigmatic example of a set of dynamic and orchestrated migratory cell behaviours. The homeobox containing transcription factor ladybird homeobox 1 (Lbx1) is a central regulator of limb myoblast migration, null mutations of Lbx1 result in severe disruptions to limb muscle formation, particularly in the distal region of the limb in mice (Gross et al., 2000). As such Lbx1 has been hypothesized to control lateral migration of myoblasts into the distal limb anlage. It acts as a core regulator of the limb myoblast migration machinery, controlled by Pax3. A secondary role for Lbx1 in the differentiation and commitment of limb musculature has also been proposed (Brohmann et al., 2000; Uchiyama et al., 2000). Here we show that lateral migration, but not differentiation or commitment of limb myoblasts, is controlled by the phosphorylation of three adjacent serine residues of LBX1. Electroporation of limb level somites in the chick embryo with a dephosphomimetic form of Lbx1 results in a specific defect in the lateral migration of limb myoblasts. Although the initial delamination and migration of myoblasts is unaffected, migration into the distal limb bud is severely disrupted. Interestingly, myoblasts undergo normal differentiation independent of their migratory status, suggesting that the differentiation potential of hypaxial muscle is not regulated by the phosphorylation state of LBX1. Furthermore, we show that FGF8 and ERK mediated signal transduction, both critical regulators of the developing limb bud, have the capacity to induce the phosphorylation of LBX1 at these residues. Overall, this suggests a mechanism whereby the phosphorylation of LBX1, potentially through FGF8 and ERK signalling, controls the lateral migration of myoblasts into the distal limb bud.
Assuntos
Extremidades/embriologia , Mioblastos/citologia , Fatores de Transcrição/fisiologia , Proteínas de Peixe-Zebra/fisiologia , Sequência de Aminoácidos , Animais , Movimento Celular , Células Cultivadas , Embrião de Galinha , MAP Quinases Reguladas por Sinal Extracelular/fisiologia , Fator 8 de Crescimento de Fibroblasto/fisiologia , Humanos , Camundongos , Mutação , Fosforilação/efeitos dos fármacos , Fosfosserina/metabolismo , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Somitos/citologia , Especificidade da Espécie , Fatores de Transcrição/genética , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/genéticaRESUMO
Genome editing is driving a revolution in the biomedical sciences that carries the promise for future treatments of genetic diseases. The CRISPR/Cas9 system of RNA-guided genome editing has been successfully applied to modify the genome of a wide spectrum of organisms. We recently showed that this technique can be combined with in vivo electroporation to inhibit the function of genes of interest in somatic cells of the developing chicken embryo. We present here a simplified version of the previously described technique that leads to effective gene loss-of-function.
Assuntos
Sistemas CRISPR-Cas , Edição de Genes/métodos , Engenharia Genética/métodos , Animais , Células Cultivadas , Embrião de Galinha , Galinhas , Eletroporação , Fibroblastos/citologia , Fibroblastos/metabolismo , Genoma , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismoRESUMO
The fusion of myoblasts into multinucleated myotubes is a crucial step of muscle growth during development and of muscle repair in the adult. While multiple genes were shown to play a role in this process, a vertebrate model where novel candidates can be tested and analyzed at high throughput and relative ease has been lacking. Here, we show that the early chicken embryo is a fast and robust model in which functional testing of muscle fusion candidate genes can be performed. We have used known modulators of muscle fusion, Rac1 and Cdc42, along with the in vivo electroporation of integrated, inducible vectors, to show that the chicken embryo is a suitable model in which their function can be tested and quantified. In addition to nuclei content, specific characteristics of the experimental model allow a fine characterization of additional morphological features that are nearly impossible to assess in other model organisms. This study should establish the chicken embryo as a cheap, reliable and powerful model in which novel vertebrate muscle fusion candidates can be evaluated.
Assuntos
Desenvolvimento Muscular , Mioblastos/metabolismo , Proteína cdc42 de Ligação ao GTP/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismo , Animais , Núcleo Celular/metabolismo , Embrião de Galinha , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Mioblastos/citologia , Proteína cdc42 de Ligação ao GTP/genética , Proteínas rac1 de Ligação ao GTP/genéticaRESUMO
How cells in the embryo coordinate epithelial plasticity with cell fate decision in a fast changing cellular environment is largely unknown. In chick embryos, skeletal muscle formation is initiated by migrating Delta1-expressing neural crest cells that trigger NOTCH signaling and myogenesis in selected epithelial somite progenitor cells, which rapidly translocate into the nascent muscle to differentiate. Here, we uncovered at the heart of this response a signaling module encompassing NOTCH, GSK-3ß, SNAI1 and ß-catenin. Independent of its transcriptional function, NOTCH profoundly inhibits GSK-3ß activity. As a result SNAI1 is stabilized, triggering an epithelial to mesenchymal transition. This allows the recruitment of ß-catenin from the membrane, which acts as a transcriptional co-factor to activate myogenesis, independently of WNT ligand. Our results intimately associate the initiation of myogenesis to a change in cell adhesion and may reveal a general principle for coupling cell fate changes to EMT in many developmental and pathological processes.
Assuntos
Transição Epitelial-Mesenquimal/genética , Células Musculares/metabolismo , Desenvolvimento Muscular/genética , Músculo Esquelético/metabolismo , Receptores Notch/genética , beta Catenina/genética , Animais , Adesão Celular , Diferenciação Celular , Membrana Celular/metabolismo , Embrião de Galinha , Citoplasma/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Glicogênio Sintase Quinase 3 beta/genética , Glicogênio Sintase Quinase 3 beta/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Células Musculares/citologia , Músculo Esquelético/citologia , Músculo Esquelético/crescimento & desenvolvimento , Crista Neural/citologia , Crista Neural/metabolismo , Receptores Notch/metabolismo , Transdução de Sinais , Fatores de Transcrição da Família Snail/genética , Fatores de Transcrição da Família Snail/metabolismo , Somitos/citologia , Somitos/metabolismo , beta Catenina/metabolismoRESUMO
Gene-targeted knockout technologies are invaluable tools for understanding the functions of genes in vivo. CRISPR/Cas9 system of RNA-guided genome editing is revolutionizing genetics research in a wide spectrum of organisms. Here, we combined CRISPR with in vivo electroporation in the chicken embryo to efficiently target the transcription factor PAX7 in tissues of the developing embryo. This approach generated mosaic genetic mutations within a wild-type cellular background. This series of proof-of-principle experiments indicate that in vivo CRISPR-mediated cell genome engineering is an effective method to achieve gene loss-of-function in the tissues of the chicken embryo and it completes the growing genetic toolbox to study the molecular mechanisms regulating development in this important animal model.
Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/fisiologia , Engenharia Genética , Animais , Sequência de Bases , Embrião de Galinha , Galinhas , Eletroporação , Genoma , Dados de Sequência Molecular , Fator de Transcrição PAX7/fisiologiaRESUMO
This review will focus on the use of the chicken and quail as model systems to analyze myogenesis and as such will emphasize the experimental approaches that are strongest in these systems-the amenability of the avian embryo to manipulation and in ovo observation. During somite differentiation, a wide spectrum of developmental processes occur such as cellular differentiation, migration, and fusion. Cell lineage studies combined with recent advancements in cell imaging allow these biological phenomena to be readily observed and hypotheses tested extremely rapidly-a strength that is restricted to the avian system. A clear weakness of the chicken in the past has been genetic approaches to modulate gene function. Recent advances in the electroporation of expression vectors, siRNA constructs, and use of tissue specific reporters have opened the door to increasingly sophisticated experiments that address questions of interest not only to the somite/muscle field in particular but also fundamental to biology in general. Importantly, an ever-growing body of evidence indicates that somite differentiation in birds is indistinguishable to that of mammals; therefore, these avian studies complement the complex genetic models of the mouse.
Assuntos
Diferenciação Celular/genética , Modelos Biológicos , Desenvolvimento Muscular/genética , Somitos/crescimento & desenvolvimento , Animais , Linhagem da Célula/genética , Embrião de Galinha , Regulação da Expressão Gênica no Desenvolvimento , Camundongos , Codorniz/crescimento & desenvolvimentoRESUMO
Skeletal muscle development, growth and regeneration depend upon the ability of muscle cells to fuse into multinucleated fibers. Surprisingly little is known about the cellular events that underlie fusion during amniote development. Here, we have developed novel molecular tools to characterize muscle cell fusion during chick embryo development. We show that all cell populations arising from somites fuse, but each with unique characteristics. Fusion in the trunk is slow and independent of fiber length. By contrast, the addition of nuclei in limb muscles is three times more rapid than in trunk and is tightly associated with fiber growth. A complex interaction takes place in the trunk, where primary myotome cells from the medial somite border rarely fuse to one another, but readily do so with anterior and posterior border cells. Conversely, resident muscle progenitors actively fuse with one another, but poorly with the primary myotome. In summary, this study unveils an unexpected variety of fusion behaviors in distinct embryonic domains that is likely to reflect a tight molecular control of muscle fusion in vertebrates.
Assuntos
Fusão Celular , Morfogênese/fisiologia , Fibras Musculares Esqueléticas/citologia , Músculo Esquelético/embriologia , Somitos/embriologia , Análise de Variância , Animais , Embrião de Galinha , Eletroporação , Imuno-Histoquímica , Indóis , Microscopia Confocal , Plasmídeos/genéticaRESUMO
In amniotes, it is widely accepted that WNTs secreted by the dorsal neural tube form a concentration gradient that regulates early somite patterning and myotome organization. Here we demonstrate in the chicken embryo that WNT protein is not secreted to act at a distance, but rather loaded onto migrating neural crest cells that deliver it to somites. Inhibiting neural crest migration or ablating their population has a profound impact on the WNT response in somites. Furthermore, we show that a central player in the efficient delivery of WNT to somites is the heparan sulfate proteoglycan GPC4, expressed by neural crest. Together, our data describe a novel mode of signaling whereby WNT proteins hitch a ride on migratory neural crest cells to pattern the somites at a distance from its source.
Assuntos
Movimento Celular/fisiologia , Via de Sinalização Wnt , Animais , Animais Geneticamente Modificados , Embrião de Galinha , Regulação da Expressão Gênica no Desenvolvimento , Glipicanas/fisiologia , Crista Neural/fisiologia , Somitos/citologia , Somitos/fisiologia , Proteínas Wnt/genética , Proteínas Wnt/metabolismo , Via de Sinalização Wnt/genética , Proteína Wnt1/genética , Proteína Wnt1/metabolismoRESUMO
Satellite cells are resident stem cells of skeletal muscle, supplying myoblasts for post-natal muscle growth, hypertrophy and repair. Many regulatory networks control satellite cell function, which includes EGF signalling via the ErbB family of receptors. Here we investigated the role of ErbB3 binding protein-1 (Ebp1) in regulation of myogenic stem cell proliferation and differentiation. Ebp1 is a well-conserved DNA/RNA binding protein that is implicated in cell growth, apoptosis and differentiation in many cell types. Of the two main Ebp1 isoforms, only p48 was expressed in satellite cells and C2C12 myoblasts. Although not present in quiescent satellite cells, p48 was strongly induced during activation, remaining at high levels during proliferation and differentiation. While retroviral-mediated over-expression of Ebp1 had only minor effects, siRNA-mediated Ebp1 knockdown inhibited both proliferation and differentiation of satellite cells and C2C12 myoblasts, with a clear failure of myotube formation. Ebp1-knockdown significantly reduced ErbB3 receptor levels, yet over-expression of ErbB3 in Ebp1 knockdown cells did not rescue differentiation. Ebp1 was also expressed by muscle cells during developmental myogenesis in mouse. Since Ebp1 is well-conserved between mouse and chick, we switched to chick to examine its role in muscle formation. In chick embryo, Ebp1 was expressed in the dermomyotome, and myogenic differentiation of muscle progenitors was inhibited by specific Ebp1 down-regulation using shRNA electroporation. These observations demonstrate a conserved function of Ebp1 in the regulation of embryonic muscle progenitors and adult muscle stem cells, which likely operates independently of ErbB3 signaling.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Desenvolvimento Muscular/fisiologia , Músculos/metabolismo , Proteínas Nucleares/metabolismo , Células-Tronco/citologia , Sequência de Aminoácidos , Animais , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Embrião de Galinha , Proteínas de Ligação a DNA , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Músculo Esquelético/metabolismo , Mioblastos/metabolismo , Proteínas Nucleares/fisiologia , Proteínas de Ligação a RNA , Receptor ErbB-3/metabolismo , Homologia de Sequência de Aminoácidos , Transdução de SinaisRESUMO
The use of shRNAmir to down-regulate the expression of genes of interest is a powerful tool for studying gene function during early chick development. However, because of the limitations of electroporation-mediated transgenesis, the down-regulation of genes expressed at late stages of development in specific tissues is difficult to perform. By combining electroporation of a doxycycline-inducible, miR30-based shRNA plasmid with the Tol2 genomic integration system, we are now able to down-regulate the expression of any gene of interest at defined stage of chicken development.
Assuntos
Galinhas/genética , Regulação da Expressão Gênica no Desenvolvimento , Animais , Embrião de Galinha , Galinhas/metabolismo , Elementos de DNA Transponíveis , Regulação para Baixo , Doxiciclina/farmacologia , Eletroporação , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Ordem dos Genes , Vetores Genéticos/genética , MicroRNAs/genética , Mutagênese Insercional , Especificidade de Órgãos/genética , Fator de Transcrição PAX7/genética , Fator de Transcrição PAX7/metabolismo , Interferência de RNA , Sequências Reguladoras de Ácido Nucleico/efeitos dos fármacosRESUMO
During embryonic and fetal life, skeletal muscle growth is dependent upon the proliferation and the differentiation of a population of resident muscle progenitors, from which derive the muscle stem cells of the adult, the satellite cells. Under poorly defined extrinsic and intrinsic influences, muscle progenitors proliferate, differentiate or enter a quiescent state to become reserve satellite cells. Despite their primordial role, surprisingly little is known on the homeostasis of resident progenitors during embryogenesis. Preliminary studies in chick and mouse describing the key progenitor populations contributing to muscle growth during embryogenesis have led to differing results that could be due to technical issues or to fundamental differences between animal models. To address this question, we have undertaken a comprehensive analysis of the state of differentiation and proliferation of muscle progenitor cells from the time of their emergence within the dermomyotome until late fetal life, when they adopt a satellite cell-like position under the basal lamina. This was done by immunostaining against key players of myogenic differentiation, in muscles chosen from different regions of the body in two model organisms, the chick and mouse. This study identified two co-existing populations of progenitors during embryonic and fetal life in both chick and mouse: a minor, slow-cycling pool of undifferentiated resident progenitors which express Pax7, co-existing with a major fast-cycling population that co-express Pax7 and the early myogenic differentiation marker Myf5. We found that the overall proliferation rate of both progenitors drastically decreased with embryonic age, as an increasingly large portion of slow and fast-cycling progenitors entered quiescence during development. Together, this data suggests that the cellular strategies that drive muscle growth during embryonic and fetal life are remarkably conserved in amniotes throughout evolution. They rely on the tight regulation of proliferation, entry in quiescence, and modulation of the cell cycle's length for both of the co-existing populations of muscle progenitors to maintain the homeostasis of growing muscles during development.
Assuntos
Evolução Biológica , Diferenciação Celular/fisiologia , Desenvolvimento Muscular/fisiologia , Músculo Esquelético/embriologia , Células Satélites de Músculo Esquelético/fisiologia , Fatores Etários , Animais , Proliferação de Células , Embrião de Galinha , Imuno-Histoquímica , Camundongos , Microscopia Confocal , Fator Regulador Miogênico 5/metabolismo , Fator de Transcrição PAX7/metabolismo , Estatísticas não ParamétricasRESUMO
Zebrafish is a common model organism in research and yet, despite its widespread use, anatomical resources for this species are incomplete or lacking in functionality. There remains a need for a single reference resource that integrates user-friendly tools to facilitate the identification of structures, display of reference images, provides data on gene expression, links to relevant literature, and covers the complete range of zebrafish developmental stages. To fulfill this need, we have designed the Zebrafish Anatomy Portal (www.zfap.org), containing annotated three-dimensional images of zebrafish at stages throughout development and adulthood, acquired by optical projection tomography. ZFAP combines functionalities to allow scanning through 3D data sets, searching of images by anatomical terms, predictions of gene expression from literature analysis, and facilitation of the identification of relevant literature through assisted searching of the NCBI PubMed resource. ZFAP provides a highly functional anatomical resource that will aid future education and research in the zebrafish model system.
Assuntos
Peixe-Zebra/anatomia & histologia , Peixe-Zebra/embriologia , Animais , Bases de Dados Factuais , Embrião não Mamífero/anatomia & histologia , Larva/anatomia & histologia , PubMed , Projetos de PesquisaRESUMO
MOTIVATION: The exponential growth of scientific literature has resulted in a massive amount of unstructured natural language data that cannot be directly handled by means of bioinformatics tools. Such tools generally require structured data, often generated through a cumbersome process of manual literature curation. Herein, we present MyMiner, a free and user-friendly text annotation tool aimed to assist in carrying out the main biocuration tasks and to provide labelled data for the development of text mining systems. MyMiner allows easy classification and labelling of textual data according to user-specified classes as well as predefined biological entities. The usefulness and efficiency of this application have been tested for a range of real-life annotation scenarios of various research topics. AVAILABILITY: http://myminer.armi.monash.edu.au.