Articles de revues sur le sujet « Nonmammalian Embryo »
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1
Mailho-Fontana, Pedro L., Marta M. Antoniazzi, Guilherme R. Coelho, Daniel C. Pimenta, Lígia P. Fernandes, Alexander Kupfer, Edmund D. Brodie et Carlos Jared. « Milk provisioning in oviparous caecilian amphibians ». Science 383, no 6687 (8 mars 2024) : 1092–95. http://dx.doi.org/10.1126/science.adi5379.
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Among vertebrates, the yolk is commonly the only form of nutritional investment offered by the female to the embryo. Some species, however, have developed parental care behaviors associated with specialized food provisioning essential for offspring survival, such as the production of lipidic-rich parental milk in mammals. Here, we show that females of the egg-laying caecilian amphibian Siphonops annulatus provide similarly lipid-rich milk to altricial hatchlings during parental care. We observed that for 2 months, S. annulatus babies ingested milk released through the maternal vent seemingly in response to tactile and acoustic stimulation by the babies. The milk, composed mainly of lipids and carbohydrates, originates from the maternal oviduct epithelium’s hypertrophied glands. Our data suggest lactation in this oviparous nonmammalian species and expand the knowledge of parental care and communication in caecilians.
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Herrmann, Anne, Arthur Taylor, Patricia Murray, Harish Poptani et Violaine Sée. « Magnetic Resonance Imaging for Characterization of a Chick Embryo Model of Cancer Cell Metastases ». Molecular Imaging 17 (1 janvier 2018) : 153601211880958. http://dx.doi.org/10.1177/1536012118809585.
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Metastasis is the most common cause of death for patients with cancer. To fully understand the steps involved in metastatic dissemination, in vivo models are required, of which murine ones are the most common. Therefore, preclinical imaging methods such as magnetic resonance imaging (MRI) have mainly been developed for small mammals and their potential to monitor cancer growth and metastasis in nonmammalian models is not fully harnessed. We have here used MRI to measure primary neuroblastoma tumor size and metastasis in a chick embryo model. We compared its sensitivity and accuracy to end-point fluorescence detection upon dissection. Human neuroblastoma cells labeled with green fluorescent protein (GFP) and micron-sized iron particles were implanted on the extraembryonic chorioallantoic membrane of the chick at E7. T2 RARE, T2-weighted fast low angle shot (FLASH) as well as time-of-flight MR angiography imaging were applied at E14. Micron-sized iron particle labeling of neuroblastoma cells allowed in ovo observation of the primary tumor and tumor volume measurement noninvasively. Moreover, T2 weighted and FLASH imaging permitted the detection of small metastatic deposits in the chick embryo, thereby reinforcing the potential of this convenient, 3R compliant, in vivo model for cancer research.
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Mercola, M., et C. D. Stiles. « Growth factor superfamilies and mammalian embryogenesis ». Development 102, no 3 (1 mars 1988) : 451–60. http://dx.doi.org/10.1242/dev.102.3.451.
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With the availability of amino acid and nucleotide sequence information has come the realization that growth factors can be clustered in to superfamilies. Several of these superfamilies contain molecules that were not initially identified because of growth-promoting activities; rather they were discovered through their ability to regulate other processes. Certain members of these superfamilies are present during early mammalian embryogenesis. However, until recently, it has been difficult to manipulate the developing mammalian embryo to observe directly the effects of inappropriate, excessive, or reduced expression of these molecules. Despite this limitation, at least some of these molecules have been implicated in the control of differentiation and morphogenesis, two actions unpredicted from the cell biology of most of the growth factors. Moreover, these actions are reflected in nonmammalian species where homologues of the mammalian growth factors control crucial steps in the choice of developmental fate. This review describes five growth factor superfamilies and the role these molecules may have in controlling proliferation, differentiation, and morphogenesis during mammalian development.
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Gibert, Yann, Victoria J. Lattanzi, Jason Holzheimer, Sarah F. Burnett et Paula G. Fraenkel. « The Zebrafish Ortholog of Hemojuvelin Participates in Notochord and Somite Development, but Fails to Regulate Embryonic Hepcidin Expression ». Blood 112, no 11 (16 novembre 2008) : 118. http://dx.doi.org/10.1182/blood.v112.11.118.118.
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Abstract Hemojuvelin (hjv), a member of the repulsive-guidance molecule (RGM) family upregulates the iron regulatory hormone hepcidin in a BMP-dependent manner in mammalian cells. A mutation interfering with hjv’s ability to bind neogenin has been identified in patients with juvenile hemochromatosis, while furin cleavage of hjv has also been implicated in its function. Previously, we demonstrated that hepcidin expression in zebrafish embryos increases in response to iron loading or activation of the BMP pathway. We hypothesized that hjv would regulate hepcidin expression in zebrafish embryos and used whole mount in situ hybridization and morpholino knockdowns to study the expression and function of hjv. We found that hjv is strongly and sequentially expressed in the notochord and somites and that knockdown of hjv resulted in severe defects in these structures. Hjv was not expressed in the liver and knockdown of hjv failed to affect the timing, intensity, or location of hepcidin expression. Furthermore, knockdown of hjv failed to prevent the upregulation of hepcidin expression caused by overexpression of BMP2b. Zebrafish hjv exhibits conservation at the site required for binding neogenin, however zebrafish hjv and all nonmammalian RGM’s lack the furin cleavage motif. We found that morpholino knockdown of the zebrafish orthologs of neogenin or furin failed to affect hepcidin expression. Taken together, these data indicate that regulation of hepcidin expression in the zebrafish embryo is BMP-responsive, but independent of hjv, furin, or neogenin zebrafish hjv participates in notochord and somite development, which we propose as the ancestral function of hjv.
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Palis, James. « Primitive and Definitive Erythropoiesis ». Blood 120, no 21 (16 novembre 2012) : SCI—37—SCI—37. http://dx.doi.org/10.1182/blood.v120.21.sci-37.sci-37.
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Abstract Abstract SCI-37 Studies in mammalian and nonmammalian vertebrate embryos indicate that erythropoiesis comes in two flavors: primitive and definitive. The primitive erythroid lineage in mammalian embryos is characterized by a transient wave of lineage-committed progenitors that emerge from the yolk sac and generate a wave of precursors that synchronously mature in the bloodstream. Primitive erythroid precursors dynamically regulate embryonic globin gene expression and ultimately enucleate to form erythrocytes. Primitive erythropoiesis is superseded by definitive erythroid cells that mature extravascularly in association with macrophage cells. Studies in the mouse embryo indicate that definitive erythropoiesis has two distinct developmental origins. The first is a transient wave of erythro-myeloid progenitors (EMP) that emerge from the yolk sac and seed the early fetal liver. The second is a long-term program of erythropoiesis derived from hematopoietic stem cells. Erythropoietin is the central regulator of definitive erythropoiesis, in part by regulating the survival of committed progenitors. In contrast, the role of erythropoietin in primitive erythropoiesis remains poorly understood. Recent studies indicate that erythropoietin does not regulate the primitive erythroid progenitor compartment, but rather plays a critical role in establishing an antiapoptotic state during the terminal maturation of primitive erythroblasts. EMP-derived proerythroblasts are capable of extensive self-renewal in vitro, while primitive erythroid progenitors are incapable of self-renewal under the same conditions. These studies, taken together, indicate that the primitive and definitive forms of erythropoiesis have fundamental differences in the regulation of red cell output. The overlapping emergence of primitive and definitive erythroid lineages in differentiating embryonic stem cells suggests that the transient yolk-sac-derived primitive and EMP-derived definitive erythroid programs are recapitulated in vitro. These studies offer the hope that human embryonic stem cells can serve as a source of functional definitive erythroid cells for transfusion therapy. Disclosures: No relevant conflicts of interest to declare.
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Swann, Karl, et F. Anthony Lai. « Egg Activation at Fertilization by a Soluble Sperm Protein ». Physiological Reviews 96, no 1 (janvier 2016) : 127–49. http://dx.doi.org/10.1152/physrev.00012.2015.
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The most fundamental unresolved issue of fertilization is to define how the sperm activates the egg to begin embryo development. Egg activation at fertilization in all species thus far examined is caused by some form of transient increase in the cytoplasmic free Ca2+ concentration. What has not been clear, however, is precisely how the sperm triggers the large changes in Ca2+ observed within the egg cytoplasm. Here, we review the studies indicating that the fertilizing sperm stimulates a cytosolic Ca2+ increase in the egg specifically by delivering a soluble factor that diffuses into the cytosolic space of the egg upon gamete membrane fusion. Evidence is primarily considered in species of eggs where the sperm has been shown to elicit a cytosolic Ca2+ increase by initiating Ca2+ release from intracellular Ca2+ stores. We suggest that our best understanding of these signaling events is in mammals, where the sperm triggers a prolonged series of intracellular Ca2+ oscillations. The strongest empirical studies to date suggest that mammalian sperm-triggered Ca2+ oscillations are caused by the introduction of a sperm-specific protein, called phospholipase C-zeta (PLCζ) that generates inositol trisphosphate within the egg. We will discuss the role and mechanism of action of PLCζ in detail at a molecular and cellular level. We will also consider some of the evidence that a soluble sperm protein might be involved in egg activation in nonmammalian species.
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Comizzoli, Pierre, et William V. Holt. « Breakthroughs and new horizons in reproductive biology of rare and endangered animal species ». Biology of Reproduction 101, no 3 (17 février 2019) : 514–25. http://dx.doi.org/10.1093/biolre/ioz031.
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Abstract Because of higher extinction rates due to human and natural factors, more basic and applied research in reproductive biology is required to preserve wild species and design proper strategies leading to sustainable populations. The objective of the review is to highlight recent, inspiring breakthroughs in wildlife reproduction science that will set directions for future research and lead to more successes in conservation biology. Despite new tools and approaches allowing a better and faster understanding of key mechanisms, we still know little about reproduction in endangered species. Recently, the most striking advances have been obtained in nonmammalian species (fish, birds, amphibians, or corals) with the development of alternative solutions to preserve fertility or new information about parental nutritional influence on embryo development. A novel way has also been explored to consider the impact of environmental changes on reproduction—the allostatic load—in a vast array of species (from primates to fish). On the horizon, genomic tools are expected to considerably change the way we study wildlife reproduction and develop a concept of “precision conservation breeding.” When basic studies in organismal physiology are conducted in parallel, new approaches using stem cells to create artificial gametes and gonads, innovations in germplasm storage, and more research on reproductive microbiomes will help to make a difference. Lastly, multiple challenges (for instance, poor integration of new tools in conservation programs, limited access to study animals, or few publication options) will have to be addressed if we want reproductive biology to positively impact conservation of biodiversity.
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TOLLNER, THEODORE L., JAMES W. OVERSTREET, MING W. LI, STUART A. MEYERS, ASHLEY I. YUDIN, EDWARD R. SALINAS et GARY N. CHERR‡. « Lignosulfonic Acid Blocks In Vitro Fertilization of Macaque Oocytes When Sperm Are Treated Either Before or After Capacitation ». Journal of Andrology 23, no 6 (12 novembre 2002) : 889–98. http://dx.doi.org/10.1002/j.1939-4640.2002.tb02347.x.
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ABSTRACT: Lignin‐derived macromolecules (LDMs) are biologically active compounds that affect a variety of cell‐to‐cell interactions including the inhibition of fertilization and embryo development in a number of nonmammalian species. The effect of lignosulfonic acid (LSA), a highly sulfonated LDM, on cynomolgus macaque sperm‐oocyte interaction was evaluated with a zona pellucida binding assay and by in vitro fertilization (IVF). Sperm were treated with LSA (1.5 mg/mL) either before washing or after capacitation. Capacitation included centrifugation through 80% Percoll followed by 2 consecutive washes with medium, overnight incubation, and activation with dibutyryl cyclic adenosine monophosphate and caffeine. The zona binding assay was performed using immature oocytes that had adhered to the center of glass “binding chambers.” The number of capacitated sperm that attached to the zona over a 3‐minute period was recorded. Sperm attachment was significantly inhibited by LSA as compared to controls whether treatment occurred after capacitation (92.5%; P < .001) or before washing (82.5%; P < .001). When sperm were treated similarly with fucoidin, a sulfated polysaccharide known to inhibit sperm‐oocyte interaction, sperm‐zona binding was significantly inhibited by postcapacitation treatment but not by prewash treatment. Treatment of sperm with LSA consistently blocked fertilization over 4 IVF cycles both before washing and after capacitation. Fertilization rate for controls was 65% ± 17%. No LSA‐treated sperm were observed on the surface of lightly rinsed oocytes after 4 hours of coincubation. Localization of biotinylated LSA showed labeling over the entire sperm surface with the greatest intensity observed over the head and midpiece. LSA treatment had no effect on the percentage of motile sperm or quality of sperm motility. Due to the antifertility properties of this nontoxic molecule, LSA appears to have potential as a vaginal contraceptive.
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Guillette, L. J., D. H. Dubois et A. Cree. « Prostaglandins, oviducal function, and parturient behavior in nonmammalian vertebrates ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 260, no 5 (1 mai 1991) : R854—R861. http://dx.doi.org/10.1152/ajpregu.1991.260.5.r854.
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Extensive data show that in mammals and birds, prostaglandins (PGs) are associated with ovulation, luteal function, oviposition, and parturition, and that also in mammals they are associated with birth-related behavior and sexual receptivity. In mammals and birds, the ability of PGs to stimulate oviducal contractions varies regionally along the oviduct (i.e., there is a functional cervix or uterovaginal region that acts to retain eggs or embryos in utero during shelling or embryonic development). Furthermore, at least in mammals, there is neural control over oviducal contractions. In reptiles, PGs stimulate oviducal contractions, and these contractions may be overridden by neural control. No data are available on whether PGs stimulate oviducal contractions in amphibians or whether there is a functional cervix in amphibians or reptiles. We suggest that in ancestral amphibians with oviparity and external fertilization, eggs moved rapidly through the oviduct after ovulation and that ovarian and oviducal PGF served as an endocrine hormone coordinating oviducal contractions and central nervous system-controlled oviposition behavior. Furthermore, we hypothesize that there was little or no neural control over oviducal contractions and no functional cervix. These conditions may still exist in present-day oviparous amphibians. In contrast, we suggest that modern-day oviparous reptiles have evolved a functional cervix and neural control over PG-induced uterine contractions, allowing egg passage to be blocked and thus the development of egg retention. These characteristics may be viewed as exaptations for the evolution of viviparity.
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Larabell, Carolyn A., David G. Capco, G. Ian Gallicano, Robert W. McGaughey, Karsten Dierksen et Kenneth H. Downing. « 3-D examination of the cytoskeletal sheets of mammalian eggs ». Proceedings, annual meeting, Electron Microscopy Society of America 50, no 1 (août 1992) : 914–15. http://dx.doi.org/10.1017/s0424820100124975.
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Mammalian eggs and embryos contain an elaborate cytoskeletal network of “sheets” which are distributed throughout the entire cell cytoplasm. Cytoskeletal sheets are long, planar structures unlike the cytoskeletal networks typical of somatic cells (actin filaments, microtubules, and intermediate filaments), which are filamentous. These sheets are not found in mammalian somatic cells nor are they found in nonmammalian eggs or embryos. Evidence that they are, indeed, cytoskeletal in nature is derived from studies demonstrating that 1) the sheets are retained in the detergent-resistant cytoskeleton fraction; 2) there are no associated membranes (determined by freeze-fracture); and 3) the sheets dissociate into filaments at the blastocyst stage of embryogenesis. Embedment-free sections of hamster eggs viewed at 60 kV show sheets running across the egg cytoplasm (Fig. 1). Although this approach provides excellent global views of the sheets and their reorganization during development, the mechanism of image formation for embedment-free sections does not permit evaluation of the sheets at high resolution.
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Singulani, Junya L., Liliana Scorzoni, Patricia B. da Silva, Ana C. Nazaré, Carlos R. Polaquini, Franciele G. Baveloni, Marlus Chorilli, Luis O. Regasini, Ana M. Fusco-Almeida et Maria JS Mendes-Giannini. « Antifungal activity and toxicity of an octyl gallate-loaded nanostructured lipid system on cells and nonmammalian animals ». Future Microbiology 17, no 4 (mars 2022) : 281–91. http://dx.doi.org/10.2217/fmb-2021-0095.
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Aim: Octyl gallate (OG) loaded into a nanostructured lipid system (NLS) was tested for antifungal activity and in vitro and in vivo toxicity. Methods & Results: The features of NLS-OG were analyzed by dynamic light scattering and showed adequate size (132.1 nm) and homogeneity (polydispersity index = 0.200). OG was active against Paraccoccidioides spp., and NLS-OG did not affect antifungal activity. NLS-OG demonstrated reduced toxicity to lung cells and zebrafish embryos compared with OG, whereas NLS was toxic to hepatic cells. OG and NLS-OG did not show toxicity in a Galleria mellonella model at 20 mg/kg. All toxic concentrations were superior to MIC (antifungal activity). Conclusion: These results indicate good anti- Paracoccidioides activity and low toxicity of NLS-OG.
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Kohno, Satomi, Melissa C. Bernhard, Yoshinao Katsu, Jianguo Zhu, Teresa A. Bryan, Brenna M. Doheny, Taisen Iguchi et Louis J. Guillette. « Estrogen Receptor 1 (ESR1 ; ERα), not ESR2 (ERβ), Modulates Estrogen-Induced Sex Reversal in the American Alligator, a Species With Temperature-Dependent Sex Determination ». Endocrinology 156, no 5 (25 février 2015) : 1887–99. http://dx.doi.org/10.1210/en.2014-1852.
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All crocodilians and many turtles exhibit temperature-dependent sex determination where the temperature of the incubated egg, during a thermo-sensitive period (TSP), determines the sex of the offspring. Estrogens play a critical role in sex determination in crocodilians and turtles, as it likely does in most nonmammalian vertebrates. Indeed, administration of estrogens during the TSP induces male to female sex reversal at a male-producing temperature (MPT). However, it is not clear how estrogens override the influence of temperature during sex determination in these species. Most vertebrates have 2 forms of nuclear estrogen receptor (ESR): ESR1 (ERα) and ESR2 (ERβ). However, there is no direct evidence concerning which ESR is involved in sex determination, because a specific agonist or antagonist for each ESR has not been tested in nonmammalian species. We identified specific pharmaceutical agonists for each ESR using an in vitro transactivation assay employing American alligator ESR1 and ESR2; these were 4,4′,4′’-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT) and 7-bromo-2-(4-hydroxyphenyl)-1,3-benzoxazol-5-ol (WAY 200070), respectively. Alligator eggs were exposed to PPT or WAY 200070 at a MPT just before the TSP, and their sex was examined at the last stage of embryonic development. Estradiol-17β and PPT, but not WAY 200070, induced sex reversal at a MPT. PPT-exposed embryos exposed to the highest dose (5.0 μg/g egg weight) exhibited enlargement and advanced differentiation of the Müllerian duct. These results indicate that ESR1 is likely the principal ESR involved in sex reversal as well as embryonic Müllerian duct survival and growth in American alligators.
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Lin, Hui-Feng, David Traver, Hao Zhu, Kimberly Dooley, Barry H. Paw, Leonard I. Zon et Robert I. Handin. « Analysis of thrombocyte development in CD41-GFP transgenic zebrafish ». Blood 106, no 12 (1 décembre 2005) : 3803–10. http://dx.doi.org/10.1182/blood-2005-01-0179.
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Thrombocytes are the nucleated equivalent of platelets in nonmammalian vertebrates such as the zebrafish, Danio rerio. We have cloned zebrafish CD41 cDNA (αIIb, glycoprotein IIb [GPIIb]) and its promoter and have generated transgenic zebrafish lines with green fluorescent protein (GFP)–tagged thrombocytes. CD41 mRNA transcripts appeared 42 hours after fertilization (hpf) by reverse-transcriptase–polymerase chain reaction (RT-PCR) and at 48 hpf in circulating hematopoietic cells. Flow sorting of thrombocytes from the mesonephros of adult CD41-GFP zebrafish showed a GFPhigh subset, which had the morphologic appearance of mature thrombocytes, and a GFPlow subset with an immature appearance, suggesting that they may be thrombocyte precursors. Confocal laser microscopy of embryos 40 and 48 hpf also showed a nonmobile population of GFP+ cells in a discrete area between the dorsal aorta and caudal vein. Production of circulating thrombocytes was inhibited by the injection of antisense morpholinos for the stem-cell transcription factor scl and c-mpl, the receptor for thrombopoietin. The nonmobile pool of GFP+ cells was abolished by scl knockdown and partially inhibited by c-mpl knockdown. These studies have shown that it is possible to identify thrombocytes, thrombocyte precursors, and, possibly, early hematopoietic stem cells in zebrafish embryos and track their proliferation and maturation.
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Ying, Ying, Xiaoxia Qi et Guang-Quan Zhao. « Induction of Primordial Germ Cells from Pluripotent Epiblast ». Scientific World JOURNAL 2 (2002) : 801–10. http://dx.doi.org/10.1100/tsw.2002.155.
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The formation of germ cells during embryogenesis bears the ultimate importance for the continuation of every species. It becomes evident that mechanisms governing germ cell fate specification are not well conserved across the animal kingdom. In most of the invertebrate and nonmammalian vertebrate species, certain maternally derived factors are key to the establishment of germ cell lineage. In contrast, mouse primordial germ cells (PGCs) are induced from the pluripotent epiblast cells before and during gastrulation by the extraembryonic cell-derived signals. The molecular identity for some of these signals has recently been revealed by genetic and epiblast culture experiments. Both bone morphogenetic proteins 4 (Bmp4) and 8b (Bmp8b) are expressed in the extraembryonic ectoderm and are required for PGC formation. Furthermore, BMP4 or BMP8B alone are unable to induce PGCs from cultured epiblasts, while they can in combination, indicating they signal through separate receptor complexes. In addition, Bmp4 homozygous embryos cannot be induced to form PGCs by the synergistic action of BMP4 and BMP8B, suggesting that BMP4 proteins produced by pregastrula embryos are required for epiblast cells to maintain pluripotency. Moreover, Bmp2, a close relative of Bmp4, is expressed in visceral endoderm at the time of PGC specification, and inactivation of Bmp2 results in a reduction in PGC number, revealing a novel function of visceral endoderm in PGC generation in the mouse.
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Li, Jiang-Yuan, Yue-Yi Wang, Tong Shao, Dong-Dong Fan, Ai-Fu Lin, Li-Xin Xiang et Jian-Zhong Shao. « The zebrafish NLRP3 inflammasome has functional roles in ASC-dependent interleukin-1β maturation and gasdermin E–mediated pyroptosis ». Journal of Biological Chemistry 295, no 4 (18 décembre 2019) : 1120–41. http://dx.doi.org/10.1074/jbc.ra119.011751.
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The NLR family pyrin domain containing 3 (NLRP3) inflammasome is one of the best-characterized inflammasomes in humans and other mammals. However, knowledge about the NLRP3 inflammasome in nonmammalian species remains limited. Here, we report the molecular and functional identification of an NLRP3 homolog (DrNLRP3) in a zebrafish (Danio rerio) model. We found that DrNLRP3's overall structural architecture was shared with mammalian NLRP3s. It initiates a classical inflammasome assembly for zebrafish inflammatory caspase (DrCaspase-A/-B) activation and interleukin 1β (DrIL-1β) maturation in an apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC)-dependent manner, in which DrNLRP3 organizes DrASC into a filament that recruits DrCaspase-A/-B by homotypic pyrin domain (PYD)–PYD interactions. DrCaspase-A/-B activation in the DrNLRP3 inflammasome occurred in two steps, with DrCaspase-A being activated first and DrCaspase-B second. DrNLRP3 also directly activated full-length DrCaspase-B and elicited cell pyroptosis in a gasdermin E (GSDME)-dependent but ASC-independent manner. These two events were tightly coordinated by DrNLRP3 to ensure efficient IL-1β secretion for the initiation of host innate immunity. By knocking down DrNLRP3 in zebrafish embryos and generating a DrASC-knockout (DrASC−/−) fish clone, we characterized the function of the DrNLRP3 inflammasome in anti-bacterial immunity in vivo. The results of our study disclosed the origin of the NLRP3 inflammasome in teleost fish, providing a cross-species understanding of the evolutionary history of inflammasomes. Our findings also indicate that the NLRP3 inflammasome may coordinate inflammatory cytokine processing and secretion through a GSDME-mediated pyroptotic pathway, uncovering a previously unrecognized regulatory function of NLRP3 in both inflammation and cell pyroptosis.
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Wu, Zhen, Yuanyuan Wu, Wei Zhang, Andres Merits, Peter Simmonds, Mingshu Wang, Renyong Jia et al. « The First Nonmammalian Pegivirus Demonstrates Efficient In Vitro Replication and High Lymphotropism ». Journal of Virology 94, no 20 (5 août 2020). http://dx.doi.org/10.1128/jvi.01150-20.
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ABSTRACT Members of the Pegivirus genus, family Flaviviridae, widely infect humans and other mammals, including nonhuman primates, bats, horses, pigs, and rodents, but are not associated with disease. Here, we report a new, genetically distinct pegivirus in goose (Anser cygnoides), the first identified in a nonmammalian host species. Goose pegivirus (GPgV) can be propagated in goslings, embryonated goose eggs, and primary goose embryo fibroblasts, and is thus the first pegivirus that can be efficiently cultured in vitro. Experimental infection of GPgV in goslings via intravenous injection revealed robust replication and high lymphotropism. Analysis of the tissue tropism of GPgV revealed that the spleen and thymus were the organs bearing the highest viral loads. Importantly, GPgV could promote clinical manifestations of goose parvovirus infection, including reduced weight gain and 7% mortality. This finding contrasts with the lack of pathogenicity that is characteristic of previously reported pegiviruses. IMPORTANCE Members of the Pegivirus genus, family Flaviviridae, widely infect humans and other mammals, but are described as causing persistent infection and lacking pathogenicity. The efficiency of in vitro replication systems for pegivirus is poor, thus limiting investigation into viral replication steps. Because of that, the pathogenesis, cellular tropism, route of transmission, biology, and epidemiology of pegiviruses remain largely uncovered. Here, we report a phylogenetically distinct goose pegivirus (GPgV) that should be classified as a new species. GPgV proliferated in cell culture in a species- and cell-type-specific manner. Animal experiments show GPgV lymphotropism and promote goose parvovirus clinical manifestations. This study provides the first cell culture model for pegivirus, opening new possibilities for studies of pegivirus molecular biology. More importantly, our findings stand in contrast to the lack of identified pathogenicity of previously reported pegiviruses, which sheds lights on the pathobiology of pegivirus.
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Fukushima, Hiroto S., Hiroyuki Takeda et Ryohei Nakamura. « Incomplete erasure of histone marks during epigenetic reprogramming in medaka early development ». Genome Research, 28 avril 2023. http://dx.doi.org/10.1101/gr.277577.122.
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Epigenetic modifications undergo drastic erasure and reestablishment after fertilization. This reprogramming is required for proper embryonic development and cell differentiation. In mammals, some histone modifications are not completely reprogrammed and play critical roles in later development. In contrast, in nonmammalian vertebrates, most histone modifications are thought to be more intensively erased and reestablished by the stage of zygotic genome activation (ZGA). However, histone modifications that escape reprogramming in nonmammalian vertebrates and their potential functional roles remain unknown. Here, we quantitatively and comprehensively analyzed histone modification dynamics during epigenetic reprogramming in Japanese killifish, medaka (Oryzias latipes) embryos. Our data revealed that H3K27ac, H3K27me3, and H3K9me3 escape complete reprogramming, whereas H3K4 methylation is completely erased during cleavage stage. Furthermore, we experimentally showed the functional roles of such retained modifications at early stages: (i) H3K27ac premarks promoters during the cleavage stage, and inhibition of histone acetyltransferases disrupts proper patterning of H3K4 and H3K27 methylation at CpG-dense promoters, but does not affect chromatin accessibility after ZGA; (ii) H3K9me3 is globally erased but specifically retained at telomeric regions, which is required for maintenance of genomic stability during the cleavage stage. These results expand the understanding of diversity and conservation of reprogramming in vertebrates, and unveil previously uncharacterized functions of histone modifications retained during epigenetic reprogramming.