Letteratura scientifica selezionata sul tema "Nonmammalian Embryo"
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Articoli di riviste sul tema "Nonmammalian Embryo"
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Mailho-Fontana, Pedro L., Marta M. Antoniazzi, Guilherme R. Coelho, Daniel C. Pimenta, Lígia P. Fernandes, Alexander Kupfer, Edmund D. Brodie e Carlos Jared. "Milk provisioning in oviparous caecilian amphibians". Science 383, n. 6687 (8 marzo 2024): 1092–95. http://dx.doi.org/10.1126/science.adi5379.
Testo completoAbstract (sommario):
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 e Violaine Sée. "Magnetic Resonance Imaging for Characterization of a Chick Embryo Model of Cancer Cell Metastases". Molecular Imaging 17 (1 gennaio 2018): 153601211880958. http://dx.doi.org/10.1177/1536012118809585.
Testo completoAbstract (sommario):
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., e C. D. Stiles. "Growth factor superfamilies and mammalian embryogenesis". Development 102, n. 3 (1 marzo 1988): 451–60. http://dx.doi.org/10.1242/dev.102.3.451.
Testo completoAbstract (sommario):
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 e Paula G. Fraenkel. "The Zebrafish Ortholog of Hemojuvelin Participates in Notochord and Somite Development, but Fails to Regulate Embryonic Hepcidin Expression". Blood 112, n. 11 (16 novembre 2008): 118. http://dx.doi.org/10.1182/blood.v112.11.118.118.
Testo completoAbstract (sommario):
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, n. 21 (16 novembre 2012): SCI—37—SCI—37. http://dx.doi.org/10.1182/blood.v120.21.sci-37.sci-37.
Testo completoAbstract (sommario):
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, e F. Anthony Lai. "Egg Activation at Fertilization by a Soluble Sperm Protein". Physiological Reviews 96, n. 1 (gennaio 2016): 127–49. http://dx.doi.org/10.1152/physrev.00012.2015.
Testo completoAbstract (sommario):
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, e William V. Holt. "Breakthroughs and new horizons in reproductive biology of rare and endangered animal species". Biology of Reproduction 101, n. 3 (17 febbraio 2019): 514–25. http://dx.doi.org/10.1093/biolre/ioz031.
Testo completoAbstract (sommario):
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 e 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, n. 6 (12 novembre 2002): 889–98. http://dx.doi.org/10.1002/j.1939-4640.2002.tb02347.x.
Testo completoAbstract (sommario):
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 e A. Cree. "Prostaglandins, oviducal function, and parturient behavior in nonmammalian vertebrates". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 260, n. 5 (1 maggio 1991): R854—R861. http://dx.doi.org/10.1152/ajpregu.1991.260.5.r854.
Testo completoAbstract (sommario):
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 e Kenneth H. Downing. "3-D examination of the cytoskeletal sheets of mammalian eggs". Proceedings, annual meeting, Electron Microscopy Society of America 50, n. 1 (agosto 1992): 914–15. http://dx.doi.org/10.1017/s0424820100124975.
Testo completoAbstract (sommario):
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.
Tesi sul tema "Nonmammalian Embryo"
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Rittenhouse, Kimberley Rochelle. "Bullwinkle, an HMG box protein, is required for proper development during oogenesis, embryogenesis and metamorphosis in Drosophila melanogaster /". Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/10267.
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Reimers, Mark J. "Ethanol-dependent developmental toxicity in zebrafish /". Connect to full text via ProQuest. IP filtered, 2005.
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DasGupta, Shamik. "Neural Circuit Analyses of the Olfactory System in Drosophila: Input to Output: A Dissertation". eScholarship@UMMS, 2009. https://escholarship.umassmed.edu/gsbs_diss/438.
Testo completoAbstract (sommario):
This thesis focuses on several aspects of olfactory processing in Drosophila. In chapter I and II, I will discuss how odorants are encoded in the brain. In both insects and mammals, olfactory receptor neurons (ORNs) expressing the same odorant receptor gene converge onto the same glomerulus. This topographical organization segregates incoming odor information into combinatorial maps. One prominent theory suggests that insects and mammals discriminate odors based on these distinct combinatorial spatial codes. I tested the combinatorial coding hypothesis by engineering flies that have only one class of functional ORNs and therefore cannot support combinatorial maps. These files can be taught to discriminate between two odorants that activate the single functional class of ORN and identify an odorant across a range of concentrations, demonstrating that a combinatorial code is not required to support learned odor discrimination. In addition, these data suggest that odorant identity can be encoded as temporal patterns of ORN activity.
Behaviors are influenced by motivational states of the animal. Chapter III of this thesis focuses on understanding how motivational states control behavior. Appetitive memory in Drosophilaprovides an excellent system for such studies because the motivational state of hunger promotes reliance on learned appetitive cues whereas satiety suppresses it. We found that activation of neuropeptide F (dNPF) neurons in fed flies releases appetitive memory performance from satiety-mediated suppression. Through a GAL4 screen, we identified six dopaminergic neurons that are a substrate for dNPF regulation. In satiated flies, these neurons inhibit mushroom body output, thereby suppressing appetitive memory performance. Hunger promotes dNPF release, which blocks the inhibitory dopaminergic neurons. The motivational drive of hunger thus affects behavior through a hierarchical inhibitory control mechanism: satiety inhibits memory performance through a subset of dopaminergic neurons, and hunger promotes appetitive memory retrieval via dNPF-mediated disinhibition of these neurons.
The aforementioned studies utilize sophisticated genetic tools for Drosophila. In chapter IV, I will talk about two new genetic tools. We developed a new technique to restrict gene expression to different subsets of mushroom body neurons with unprecedented precision. We also adapted the light-activated adenylyl cyclase (PAC) from Euglena gracilis as a light-inducable cAMP system for Drosophila. This system can be used to induce cAMP synthesis in targeted neurons in live, behaving preparations.
Capitoli di libri sul tema "Nonmammalian Embryo"
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Maden, Malcolm. "Retinoids in Nonmammalian Embryos". In METHODS IN MOLECULAR BIOLOGY™, 541–59. Totowa, NJ: Humana Press, 2008. http://dx.doi.org/10.1007/978-1-60327-483-8_37.
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Pelster, Bernd. "Oxygen, temperature, and pH influences on the development of nonmammalian embryos and larvae". In Development of Cardiovascular Systems, 227–39. Cambridge University Press, 1998. http://dx.doi.org/10.1017/cbo9780511601095.019.
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