• The researchers were able to identify the minimal conditions and factors that would be sufficient for starting the cascade of molecular and cellular processes to instruct pluripotent cells to organize the embryo. (wikipedia.org)
  • They showed that opposing gradients of bone morphogenetic protein (BMP) and Nodal, two transforming growth factor family members that act as morphogens, are sufficient to induce molecular and cellular mechanisms required to organize, in vivo or in vitro, uncommitted cells of the zebrafish blastula animal pole into a well-developed embryo. (wikipedia.org)
  • This question had been asked by embryologists since 1886 ( Rauber, 1886 ), and Spemann ( Spemann, 1938 ) had demonstrated by an egg ligation experiment that the nuclei of an eight-cell frog embryo are developmentally totipotent. (biologists.com)
  • However, Briggs and King ( Briggs and King, 1957 ) had also found that the nucleus of an endoderm cell from a neurula embryo could no longer support normal development ( Fig. 2 ). (biologists.com)
  • Fourth, each cell of the developing frog embryo contains yolk platelets that provide nutrition during prefeeding stages of embryonic life. (biomedcentral.com)
  • But it is perhaps not auspicious to quote him for purposes of the scientific debates on human cloning, because Ramsey agreed with and supported the scientific myth of the "pre-embryo" 47 made famous by Jesuit Richard McCormick and frog embryologist Clifford Grobstein. (lifeissues.net)
  • In animals , parthenogenesis means development of an embryo from an unfertilized egg cell. (alchetron.com)
  • Gynogenesis and pseudogamy are closely related phenomena in which a sperm or pollen triggers the development of the egg cell into an embryo but makes no genetic contribution to the embryo. (alchetron.com)
  • He and his team described the biological processes related to reproductive cyclicity, sperm, egg and embryo development in carnivores, especially felids and canids. (si.edu)
  • Analyses of A. thaliana mutants of these components show that completion of the sperm nuclear fusion at fertilization is essential for proper embryo and endosperm development. (preprints.org)
  • METHODS: Using RT-PCR, we detected the presence of epididymis-specific genes (Adam7, Crisp1, Defb22, Wfdc2, and Wfdc9) in the testis, epididymis, epididymosome and sperm of adult male BALB/c mice as well as in the human testis, seminal vesicles and sperm. (bvsalud.org)
  • One example is the transformation of iris cells to lens cells in the process of maturation and transformation of retinal pigment epithelium cells into the neural retina during regeneration in adult newt eyes. (wikipedia.org)
  • The fact that transdetermination (change of the path of differentiation) often occurs for a group of cells rather than single cells shows that it is induced rather than part of maturation. (wikipedia.org)
  • Members of the frog Xenopus genus are versatile model organisms used in developmental biology, cell biology, neuroscience, and toxicology research, among others. (cshlpress.com)
  • Studies using Xenopus cell-free extracts, oocytes, eggs, embryos, larval stages, and adult frogs have yielded important insights into a multitude of key biological processes-from mechanisms underlying the cell cycle to embryonic development to human disease. (cshlpress.com)
  • It is a critical reference for laboratories that currently work with these organisms and will serve as an essential start-up guide for those seeking to start using Xenopus frogs in their research for the first time. (cshlpress.com)
  • As a brand new graduate student starting in October 1956, my supervisor Michail Fischberg, a lecturer in the department of Zoology at Oxford, suggested that I should try to make somatic cell nuclear transplantation work in the South African frog Xenopus laevis . (biologists.com)
  • Even advanced donor cells from the endoderm of Xenopus tadpoles have nuclei that can sometimes yield normal individuals after nuclear transfer [data taken from Briggs and King ( Briggs and King, 1957 ) for Rana and from Gurdon ( Gurdon, 1962 ) for Xenopus ]. (biologists.com)
  • The frog Xenopus laevis has been an important model of vertebrate cell biology and development for many decades. (biomedcentral.com)
  • The frog Xenopus laevis has been used to study early stages of vertebrate development for more than 50 years and continues to be an important model system. (biomedcentral.com)
  • The closely related frog Xenopus tropicalis shares all the features of X. laevis that make this system useful for embryonic manipulation but it develops more rapidly (sexual maturity is reached in 5 to 9 months) and has a diploid genome. (biomedcentral.com)
  • Induced totipotent cells can be obtained by reprogramming somatic cells with somatic-cell nuclear transfer (SCNT). (wikipedia.org)
  • This allows explanted cells to survive in simple salt solutions for several days and enables study of isolated embryonic tissues and cells. (biomedcentral.com)
  • When studying an individual organism, a biologist could examine the cell and its organelles, the tissues that the cells make up, the organs and their respective organ systems, and the sum total-the organism itself. (dokumen.pub)
  • At the level of the cell, in tissues involved in secretory functions, such as the salivary glands, the cells have abundant Golgi. (dokumen.pub)
  • It cannot be detected in the unfertilized egg, sperm or differentiated tissues such as liver or muscle. (silverchair.com)
  • Frogs are easy to rear and maintain, and large sample sizes of embryos and later stages are readily obtained. (cshlpress.com)
  • In the axolotl, DNA-ligase I (8S) is specific for embryonic stages. (silverchair.com)
  • Normal egg cells form after meiosis and are haploid, with half as many chromosomes as their mother's body cells. (alchetron.com)
  • A) Unfertilized egg and diploid blastula 24 h, (B) haploid androgenetic blastula 24h, (C) axolotl activated egg implanted with Pleurodeles blastula nucleus, diploid, (D) axolotl activated egg, implanted with Pleurodeles haploid androgenetic nucleus, (E) same experiment as D, except a transient treatment with spermine of the transplanted nucleus. (silverchair.com)
  • They provide the structure and shape necessary for proteins and DNA within cells so that they function properly. (dokumen.pub)
  • Using random forest analysis, SACA4 and LAMB2 were identified as the sperm proteins with a higher chance of distinguishing ID and UMI patients, and their function and expression variation were in accordance with the functional results. (bvsalud.org)
  • So, rather than one molecule that is therapeutic, we think that the exosomes contain a cocktail of molecules and proteins that can, all together, help the cell maintain homeostasis, deal with the stress, modify metabolic action and reduce the amount of injury. (regenerativemedicine.net)
  • The team also found that injured cardiomyocytes that had been treated with EEVs exhibited a set of proteins that was more similar to the uninjured ones compared with untreated cells. (regenerativemedicine.net)
  • Our findings indicate that EEVs could protect cardiac tissue from reoxygenation injury in part by supplementing the injured cells with proteins and signaling molecules that support different metabolic processes, paving the way for new therapeutic approaches," said Andr G. Kl ber, a Visiting Professor of Pathology at Harvard Medical School and co-author of the study. (regenerativemedicine.net)
  • The equatorial segment of the acrosome underlies the domain of the sperm that fuses with the egg membrane during fertilization. (bioone.org)
  • Acrosin (ACRO) and sperm acrosome membrane-associated protein 4 (SACA4) were downregulated in ID patients while laminin subunit beta-2 (LAMB2), mannose 6-phosphate isomerase (MPI), ATP-dependent 6-phosphofructokinase liver type (PFKAL), STAR domain-containing protein 10 (STA10), serotransferrin (TRFE) and exportin-2 (XPO2) were downregulated in UMI patients. (bvsalud.org)
  • They are classified as either totipotent (iTC), pluripotent (iPSC) or progenitor (multipotent - iMSC, also called an induced multipotent progenitor cell - iMPC) or unipotent - (iUSC) according to their developmental potential and degree of dedifferentiation. (wikipedia.org)
  • Genetic manipulation of this tractable model system would further enhance the use of the frog in developmental studies. (biomedcentral.com)
  • Transposon vectors can be used in the frog for transgenesis and for insertional mutagenesis where enhancer trap and gene trap constructs are used to identify genomic loci involved in developmental processes. (biomedcentral.com)
  • Several features of amphibian embryonic life make these animals useful as models for studying early developmental events. (biomedcentral.com)
  • Depending on the developmental stage and the tissue considered, types of cell are available that express exclusively either one or the other of the two DNA-ligases with a defined level of activity. (silverchair.com)
  • hESCs can be generated by SCNT using dermal fibroblasts nuclei from both a middle-aged 35-year-old male and an elderly, 75-year-old male, suggesting that age-associated changes are not necessarily an impediment to SCNT-based nuclear reprogramming of human cells. (wikipedia.org)
  • Induced stem cells (iSC) are stem cells derived from somatic, reproductive, pluripotent or other cell types by deliberate epigenetic reprogramming. (wikipedia.org)
  • With stem cell biology and molecular understanding of reproductive failure, new therapies for previously untreatable infertility are currently on the near horizon. (infertile.com)
  • Mature egg cells are produced by mitotic divisions, and these cells directly develop into embryos. (alchetron.com)
  • Briggs and King ( Briggs and King, 1952 ) had already succeeded in transplanting a blastula cell nucleus into an enucleated egg and obtaining normal tadpoles in the frog Rana pipiens . (biologists.com)
  • The team also demonstrated that these intercellular travelers could be derived from endothelial cells, which line the surface of blood vessels and are more abundant and easier to maintain than stem cells. (regenerativemedicine.net)
  • In our study, we conducted a thorough analysis and unveiled a multitude of abnormalities in zebrafish sperm and testicular tissue caused by ZPT exposure, including a dose-dependent diminishing of testosterone levels, various sperm deformities, decreased sperm concentration and motility, and ROS-induced testicular tissue DNA damage. (bvsalud.org)
  • The genes and pathways uncovered in this study point to potential mechanisms of ZPT exposure on sperm and testicular injury in zebrafish. (bvsalud.org)
  • Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have unraveled potential mechanisms behind the healing power of EVs and demonstrated their capacity to not only revive cells after a heart attack but keep cells functioning while deprived of oxygen during a heart attack. (regenerativemedicine.net)
  • The frog lays abundant eggs that are large, develop synchronously, and are easy to manipulate. (biomedcentral.com)
  • The process involves sucking out the nucleus of a somatic (body) cell and injecting it into an oocyte that has had its nucleus removed Using an approach based on the protocol outlined by Tachibana et al. (wikipedia.org)
  • It was clear that a definitive experiment required the replacement of a zygote nucleus by a somatic cell nucleus, asking whether the somatic nucleus could functionally replace the zygote nucleus by eliciting normal development of the enucleated recipient egg ( Fig. 1 )? (biologists.com)
  • Sperm samples were evaluated functionally, mitochondrially and using proteomics. (bvsalud.org)
  • Once integrated into the frog genome, the 'cut-and-paste' DNA transposons are targets for remobilization by re-expression of the appropriate transposase enzyme. (biomedcentral.com)
  • Transgenic frogs that express the enzyme in the germline can be bred with animals harboring a transposon substrate to generate double transgenic lines where remobilization will occur in the germline in subsequent generations. (biomedcentral.com)
  • DNA-ligase activity in eukaryotic cells is carried out by two different molecular forms of the enzyme. (silverchair.com)
  • In fact, the normal level of activity for the heavy molecular form of the enzyme has been established by the time the egg enters cleavage, 7h after activation. (silverchair.com)
  • In the same cytoplasmic environment, and following egg activation and DNA replication, the gene for DNA-ligase I introduced by the male pronucleus is unable to direct any production of the corresponding enzyme. (silverchair.com)
  • The high fecundity of the frog combined with the ability to remobilize transposon transgenes integrated into frog genome will allow large-scale insertional mutagenesis screens to be performed in laboratories with modest husbandry capacities. (biomedcentral.com)
  • During the life cycle of flowering plants, nuclear fusion occurs three times: once during female gametogenesis and twice during double fertilization, when two sperm cells fertilize the egg and the central cell. (preprints.org)
  • Some types of mature, specialized adult cells can naturally revert to stem cells. (wikipedia.org)
  • For instance, multilineage-differentiating stress-enduring (Muse) cells are stress-tolerant adult human stem cells that can self-renew. (wikipedia.org)
  • main target cells are in the part of the brain called the suprachiasmatic nucleus (SCN). (optimalhealth.in)
  • Progenitors are obtained by so-called direct reprogramming or directed differentiation and are also called induced somatic stem cells. (wikipedia.org)
  • For example, "chief" cells express the stem cell marker Troy. (wikipedia.org)
  • While they normally produce digestive fluids for the stomach, they can revert into stem cells to make temporary repairs to stomach injuries, such as a cut or damage from infection. (wikipedia.org)
  • Moreover, they can make this transition even in the absence of noticeable injuries and are capable of replenishing entire gastric units, in essence serving as quiescent "reserve" stem cells. (wikipedia.org)
  • Differentiated airway epithelial cells can revert into stable and functional stem cells in vivo. (wikipedia.org)
  • This capacity to regenerate does not decline with age and may be linked to their ability to make new stem cells from muscle cells on demand. (wikipedia.org)
  • A variety of nontumorigenic stem cells display the ability to generate multiple cell types. (wikipedia.org)
  • and human spermatogenic stem cell culture to treat azoospermia, and to preserve fertility in pre-pubertal boys undergoing cancer treatment. (infertile.com)
  • A third experiment involved testing two drugs, originally developed to stimulate stem cell activity in the eyes and pancreas, that are known activate ERBB2 signaling. (regenerativemedicine.net)
  • The researchers found that activating the ERBB2 pathway triggered a cascading series of cellular events by which cochlear support cells began to proliferate and start the process of activating other neighboring stem cells to become new sensory hair cells. (regenerativemedicine.net)
  • EVs derived from stem cells have already been shown to help heart cells recover after a heart attack, but exactly how they help and whether the beneficial effect is specific to EVs derived from stem cells has remained a mystery. (regenerativemedicine.net)
  • Third, many amphibian species lay vast numbers of eggs, providing adequate numbers for study. (biomedcentral.com)
  • His team conducted the first successful transcontinental shipment of frozen sperm from a threatened species (a wild cheetah in Namibia) to produce a cub by artificial insemination in North America. (si.edu)
  • His laboratory also produced black-footed ferret kits using sperm that had been cryo-banked for 20 years ' a milestone that increases gene diversity in the recovering population of this critically endangered species. (si.edu)
  • David Wildt leads the Center for Species Survival team that has generated much of what we now know about how many wildlife species reproduce (from frogs to elephants). (si.edu)
  • After injury, mature terminally differentiated kidney cells dedifferentiate into more primordial versions of themselves and then differentiate into the cell types needing replacement in the damaged tissue Macrophages can self-renew by local proliferation of mature differentiated cells. (wikipedia.org)
  • Subsequently, ESP was localized to electron-dense regions of the equatorial segment and the expanded equatorial bulb in elongating spermatids and mature sperm. (bioone.org)
  • In newts, muscle tissue is regenerated from specialized muscle cells that dedifferentiate and forget the type of cell they had been. (wikipedia.org)
  • Muscle cells also must repair muscle tissue damaged by exercise by building new muscle. (dokumen.pub)
  • Extracellular vesicles (EVs) -- nanometer sized messengers that travel between cells to deliver cues and cargo -- are promising tools for the next generation of therapies for everything from autoimmune and neurodegenerative diseases to cancer and tissue injury. (regenerativemedicine.net)
  • The researchers induced injury by three hours of oxygen restrictions followed by 90 minutes of reoxygenation and then measured the fraction of dead cells and the contractile force of the tissue. (regenerativemedicine.net)
  • The heart tissue treated with EEVs had half as many dead cells and had a contractile force four times higher than the untreated tissue after injury. (regenerativemedicine.net)
  • But we have no solid evidence for what is the threshold, if any, for the sperm count to exceed in order to allow the male to be fertile [4,5,7]. (infertile.com)
  • In 1924 Hans Spemann and Hilde Mangold demonstrated the key importance of cell-cell inductions during animal development. (wikipedia.org)
  • You have to regenerate sensory hair cells and these cells have to function properly and connect with the necessary network of neurons. (regenerativemedicine.net)
  • The Honeycomb Game is a word-building game: make words by clicking on cells in the honeycomb below. (claylane.uk)
  • The researchers focused on a specific receptor called ERBB2 which is found in cochlear support cells. (regenerativemedicine.net)
  • Research conducted in the lab of Patricia White, Ph.D., in 2012 identified a family of receptors -- called epidermal growth factor (EGF) -- responsible for activating support cells in the auditory organs of birds. (regenerativemedicine.net)
  • In a new study scientists have been able to regrow the sensory hair cells found in the cochlea -- a part of the inner ear -- that converts sound vibrations into electrical signals and can be permanently lost due to age or noise damage. (regenerativemedicine.net)
  • With this study, we have mimicked a human disease on a chip with human cells and developed a novel therapeutic approach to treat it. (regenerativemedicine.net)
  • Since HIV-1 spreads via both free virions and cell-cell fusion, we examined the effect of the antibodies on HIV-1 Env-mediated cell-cell fusion. (preprints.org)
  • They form characteristic cell clusters in suspension culture that express a set of genes associated with pluripotency and can differentiate into endodermal, ectodermal and mesodermal cells both in vitro and in vivo. (wikipedia.org)
  • Wildt described the impact of small populations and inbreeding on sperm form and function, including on free-living cheetahs and lions. (si.edu)
  • This meant that the cells can change their differentiation pathway. (wikipedia.org)
  • Our research is focused on finding a way to switch the pathway temporarily, in order to promote both regeneration of hair cells and their integration with nerve cells, both of which are critical for hearing. (regenerativemedicine.net)
  • In mice, the cochlea expresses EGF receptors throughout the animal's life, but they apparently never drive regeneration of hair cells," said White. (regenerativemedicine.net)
  • Furthermore, it appears that this process not only could impact the regeneration of sensory hair cells, but also support their integration with nerve cells. (regenerativemedicine.net)
  • Clone69TRevEnv cells that express Env in the absence of tetracycline were labeled with Calcein-AM Green, and incubated with CD4+ SupT1 cells labeled with CellTraceā„¢ Calcein Red-Orange, with or without antibodies. (preprints.org)
  • PG9, PG16, PGT121, and PGT145 antibodies were identified from culture media of activated memory B-cells of an infected donor and shown to neutralize many HIV-1 strains. (preprints.org)
  • OBJECTIVE: To investigate whether mouse epididymis-specific mRNAs Adam7 and Crisp1 can be delivered into N2a and TM4 cells, and to provide an experimental basis for exploring the function of epididymal mRNAs. (bvsalud.org)
  • 4 C 6 D 8 D 10 A 12 C 15 The advantages of light microscopes are that they are easily obtained, and the light beam does not kill the cells. (dokumen.pub)
  • Second, the eggs are large and easy to manipulate under low power microscopy. (biomedcentral.com)
  • A baby developing from a fertilized egg is an endergonic process. (dokumen.pub)
  • In flowering plants, cells of the gametophyte can undergo this process. (alchetron.com)
  • Of course, the best way to treat a heart attack is to restore blood flow but that process actually may cause more damage to the cells in the heart. (regenerativemedicine.net)
  • The very important question to be addressed at that time was whether all cell types in the body have the same set of genes. (biologists.com)
  • Body cells break down sugars to provide ATP to do the work necessary for exercise, such as muscle contractions. (dokumen.pub)
  • Conveys high-speed electrical signals along specialized cells called neurons rapid messages control the movement of body parts. (optimalhealth.in)
  • Chapter 3 1 Figure 3.7 Plant cells have plasmodesmata, a cell wall, a large central vacuole, chloroplasts, and plastids. (dokumen.pub)
  • Transposable elements will provide invaluable tools for manipulating the frog genome. (biomedcentral.com)
  • Animal cells have lysosomes and centrosomes. (dokumen.pub)
  • According to our results, ID patients presented the worst sperm functional profile, while UMI patients were similar to controls. (bvsalud.org)