• The artificial cloning of organisms, sometimes known as reproductive cloning, is often accomplished via somatic-cell nuclear transfer (SCNT), a cloning method in which a viable embryo is created from a somatic cell and an egg cell. (wikipedia.org)
  • 2. Nuclear transfer is a technique used to duplicate genetic material by creating an embryo through the transfer and fusion of a diploid cell in an enucleated female oocyte.2 Cloning has a broader meaning than nuclear transfer as it also involves gene replication and natural or induced embryo splitting (see Annex 1). (who.int)
  • During the development of vertebrates, including humans, the fertilized egg develops into the embryo, and the cells in the embryo then proceed to differentiate to form somatic cells of different tissues and organs. (shawprize.org)
  • The fertilized egg is considered totipotent, as it can develop into a whole organism, while the cells in the embryo are pluripotent because they are capable of differentiating into somatic cells that make up all the organs. (shawprize.org)
  • They pioneered a new technique of starving embryo cells before transferring their nucleus to fertilized egg cells. (shawprize.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)
  • 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)
  • Fourth, each cell of the developing frog embryo contains yolk platelets that provide nutrition during prefeeding stages of embryonic life. (biomedcentral.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)
  • An organizer population has been identified in the anterior end of the primitive streak of the mid-streak stage embryo, by the expression of Hnf3β , Gsc lacZ and Chrd , and the ability of these cells to induce a second neural axis in the host embryo. (silverchair.com)
  • This cell population can therefore be regarded as the mid-gastrula organizer and, together with the early-gastrula organizer and the node, constitute the organizer of the mouse embryo at successive stages of development. (silverchair.com)
  • Fine mapping of the epiblast in the posterior region of the early-streak stage embryo reveals that although the early-gastrula organizer contains cells that give rise to the axial mesoderm, the bulk of the progenitors of the head process and the notochord are localized outside the early gastrula organizer. (silverchair.com)
  • Cells that are fated for the head process move anteriorly from the mid-gastrula organizer in a tight column along the midline of the embryo. (silverchair.com)
  • Dorsoventral (DV) patterning of the Drosophila embryo is initiated by a broad Dorsal (Dl) nuclear gradient, which is regulated by a conserved signaling pathway that includes the Toll receptor and Pelle kinase. (sdbonline.org)
  • Using the bicoid 3' UTR, localized Toll(10b) products result in the formation of an ectopic, anteroposterior (AP) Dl nuclear gradient along the length of the embryo. (sdbonline.org)
  • 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)
  • They performed nuclear transfer experiments in which nuclei from embryonic, foetal and adult cells of the sheep were transplanted into fertilized eggs derived from ewes. (shawprize.org)
  • 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)
  • Transplantation of living nuclei from blastula cells into enucleated frogs' eggs. (chinagene.cn)
  • Cytoplasmic impact on cross-genus cloned fish derived from transgenic common carp ( Cyprinus carpio ) nuclei and gold-fish ( Carassius auratus ) enucleated eggs. (chinagene.cn)
  • 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)
  • For instance, effective transfer of programmable nucleases to living cells, tissues, or organs that contain the target gene is important for genome editing. (molcells.org)
  • In 1996, Dolly the sheep achieved notoriety for being the first mammal cloned from a somatic cell. (wikipedia.org)
  • Somatic-cell nuclear transfer, the technique by which Dolly was created, was first used 40 years ago in research with tadpoles and frogs. (who.int)
  • The nucleus of an adult somatic cell (such as a skin cell) is removed and transferred to an enucleated egg, which is then stimulated with electric current or chemicals to activate cell division. (who.int)
  • if it implants and the pregnancy goes to term, the resulting individual will carry the same nuclear genetic material as the donor of the adult somatic cell. (who.int)
  • Scientists were initially interested in somatic-cell nuclear transfer as a means of determining whether genes remain functional even after most of them have been switched off as the cells in a developing organism assume their specialized functions as blood cells, muscle cells, and so forth. (who.int)
  • 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)
  • 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)
  • 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)
  • This Spotlight article is a commentary on the early nuclear transplant work in Xenopus , which was very important for the Nobel award in 2012, and the influence of this work on the reprogramming field. (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)
  • However, an animal created through this technique would not be a precise genetic copy of the source of its nuclear DNA because each clone derives a small amount of its DNA from the mitochondria of the egg (which lie outside the nucleus) rather than from the donor of cell nucleus. (who.int)
  • Thus, the clone would be genetically identical to the nucleus donor only if the egg came from the same donor or from her maternal line. (who.int)
  • One of the live-born lambs, Dolly, was derived from the transplantation of the nucleus of an adult mammary cell. (shawprize.org)
  • 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 bound complex is internalized and translocates into the oocyte nucleus thanks to an SV40 nuclear localization signal, enhanced by an adjacent casein kinase phosphorylation site. (biologists.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)
  • main target cells are in the part of the brain called the suprachiasmatic nucleus (SCN). (optimalhealth.in)
  • The use of embryonic stem cells, which can be produced through SCNT, in some stem cell research has attracted controversy. (wikipedia.org)
  • 5. In 2001, France and Germany requested the United Nations General Assembly to develop international conventions on human reproductive cloning, therapeutic cloning and research on stem cells. (who.int)
  • 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)
  • 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)
  • 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)
  • It may occur accidentally in the case of identical twins, which are formed when a fertilized egg splits, creating two or more embryos that carry almost identical DNA. (wikipedia.org)
  • Transposable elements will provide invaluable tools for manipulating the frog genome. (biomedcentral.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)
  • Here, we review the application of transposable elements to modification of the frog genome. (biomedcentral.com)
  • 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)
  • Let's transplant the genome of species A in a cell of species B and see whether the resulting individuals will resemble species A, species B, or something else. (blogspot.com)
  • If you are correct, then the result should not look like the genome donor species A, right? (blogspot.com)
  • This article summarizes the history and current situation in fish nuclear transfer tech-nology and discusses the factors that may influence the development of the cloned embryos. (chinagene.cn)
  • There are five distinct thresholds of gene activity in response to the Dorsal nuclear gradient in early embryos. (sdbonline.org)
  • A fertilized egg of Ciona intestinalis develops within 18 hours to a larva, which consists of approximately 2600 cells with distinct cell types, including epidermis, nervous system, muscle, notochord, mesenchyme, and endoderm. (oist.jp)
  • The equatorial segment of the acrosome underlies the domain of the sperm that fuses with the egg membrane during fertilization. (bioone.org)
  • 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)
  • Attempts were then made to show that mammalian cells - and human cells in particular - could also be reprogrammed back to a pluripotent state, because it is believed that such knowledge may advance our understanding of developmental mechanisms, and yield new approaches for disease treatment. (shawprize.org)
  • The frog lays abundant eggs that are large, develop synchronously, and are easy to manipulate. (biomedcentral.com)
  • The fact that the DNA of a fully differentiated (adult) cell could be stimulated to revert to a condition comparable to that of a newly fertilized egg and to repeat the process of embryonic development demonstrates that all the genes in differentiated cells retain their functional capacity, although only a few are active. (who.int)
  • The scientists honoured by the 2008 Shaw Prize in Life Science and Medicine used different approaches to reprogramme an adult cell into the totipotent or pluripotent state, and in doing so made important contributions to potential new approaches to improve agriculture practices and to treat human diseases. (shawprize.org)
  • Thus, Dolly was the first example of the reprogramming of the adult cell back to totipotency in a mammal. (shawprize.org)
  • Viable offspring derived from fetal and adult mam-malian cells. (chinagene.cn)
  • Another example of artificial cloning is molecular cloning, a technique in molecular biology in which a single living cell is used to clone a large population of cells that contain identical DNA molecules. (wikipedia.org)
  • The term applies not only to entire organisms but also to copies of molecules (such as DNA) and cells. (who.int)
  • The protein and RNA molecules produced by cells associate with each other in a context-dependent fashion or, in many cases, catalyze chemical reactions (generating lipids, polysaccharides and other molecules), whose rates depend on the temperature and composition of the external environment. (blogspot.com)
  • So the population of molecules inside the cell can vary extensively even if the genes do not. (blogspot.com)
  • 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)
  • 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)
  • 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)
  • Fruit flies of the species Drosophila melanogaster develop from eggs to adults in eight to ten days at 25 degrees Celsius. (asu.edu)
  • Third, many amphibian species lay vast numbers of eggs, providing adequate numbers for study. (biomedcentral.com)
  • 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)
  • 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)
  • Taking advantage of this simple mode of embryogenesis, as well as well-characterized genes involved in developmental, Ciona is now a model experimental system for exploring gene regulatory networks for differentiation of embryonic cells [Imai et al. (oist.jp)
  • Half a century ago, it was found by John Gurdon that this developmental clock can be reversed, and that differentiated somatic cells in a frog model could regain their pluripotency or totipotency. (shawprize.org)
  • Genetic manipulation of this tractable model system would further enhance the use of the frog in developmental studies. (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)
  • 2012)]. In collaboration with other labs, we are now carrying out several experiments to understand the developmental mechanisms of notochord formation at the single-cell level. (oist.jp)
  • Ian Wilmut and Keith H S Campbell worked together in the Roslin Institute near Edinburgh for many years, using sheep as the model, in order to understand the early physiology of the egg and how laboratory manipulations can improve our knowledge of the development from egg to birth. (shawprize.org)
  • 1) The experimenter dissects a donor larva, which is in the third instar stage of development, and removes the optic disc (colored red) with a micropipette. (asu.edu)
  • Once perceived as an unimportant occurrence in living organisms, cell degeneration was reconfigured as an important biological phenomenon in development, aging, health, and diseases in the twentieth century. (asu.edu)
  • 1] Spemann H. Embryonic development and induction. (chinagene.cn)
  • In the field of biotechnology, cloning is the process of creating cloned organisms of cells and of DNA fragments. (wikipedia.org)
  • 3. Media reports on nuclear transfer are usually about one form, reproductive nuclear transfer, also known as reproductive cloning of human beings . (who.int)
  • As an important sub-field in the study of animal cloning, fish nuclear transfer was first established in the early 1960s by Chinese embryologists. (chinagene.cn)
  • A comprehensive understand-ing of the mechanism for epigenetic modification following nuclear transfer, such as genomic DNA methylation and histone acetylation and/or methylation, will likely increase the success rate and eventually lead to the future freedom of cloning technique. (chinagene.cn)
  • 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)
  • 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)
  • The nuclear fusion process in plant reproduction is achieved by the sequential nuclear membrane fusion events. (preprints.org)
  • Recent molecular genetic analyses using Arabidopsis thaliana showed the conservation of nuclear membrane fusion machinery between plants and the budding yeast Saccharomyces cerevisiae. (preprints.org)
  • These include the heat shock protein 70 in the endoplasmic reticulum and conserved nuclear membrane proteins. (preprints.org)
  • In sexual reproduction, clones are created when a fertilized egg splits to produce identical (monozygous) twins with identical genomes. (who.int)
  • 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)
  • Since, as described above, the composition of the cell's interior and the activity of many of its proteins depend on more than just the genes, the portion of the genes' information content that is actually used by the cell is determined, in part, by non-genetic factors. (blogspot.com)
  • All eighteen of the Advisory Committees recommendations are presented in Chapter 2 of this edition as part of a general review of long waiting lists and the increasing importance of living organ donors. (binaryoptiontradingscam.com)
  • After roughly a day, each egg hatches into a larva. (asu.edu)
  • the rate at which a protein is synthesized, which depends on factors internal and external to the cell, affects the order in which its different portions fold. (blogspot.com)
  • A baby developing from a fertilized egg is an endergonic process. (dokumen.pub)
  • In the mid-gastrula organizer, early gastrula organizer derived cells that are fated for the prechordal mesoderm are joined by the progenitors of the head process that are recruited from the epiblast previously anterior to the early gastrula organizer. (silverchair.com)
  • 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)
  • 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 profile of genetic activity and the tissue contribution by cells in the organizer change during gastrulation, suggesting that the organizer may be populated by a succession of cell populations with different fates. (silverchair.com)
  • Before there were multicellular forms, single-celled organisms evolved for as much as two billion years driven, in part, by genetic change, as well as by establishment of persistent symbiotic relationships among simpler cells. (blogspot.com)
  • They provide the structure and shape necessary for proteins and DNA within cells so that they function properly. (dokumen.pub)
  • 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)
  • The technique synchronized the cell cycles of both cells and the results led Wilmut and Campbell to believe that any type of cell could be used to produce a clone. (shawprize.org)
  • The use of the technique of nuclear transfer for reproduction of human beings is surrounded by strong ethical concerns and controversies and is considered a threat to human dignity. (who.int)
  • Due to its advantages, zebrafish has become a unique animal model to study the mystery of reprogramming in nuclear transfer. (chinagene.cn)
  • Nuclear transfer and reprogramming in fish[J]. HEREDITAS, 2013, 35(4): 433-440. (chinagene.cn)
  • 12] Lee KY, Huang HG, Ju BS, Yang ZG, Lin S. Cloned ze-brafish by nuclear transfer from long-term-cultured cells. (chinagene.cn)
  • The Honeycomb Game is a word-building game: make words by clicking on cells in the honeycomb below. (claylane.uk)
  • 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)
  • The researchers focused on a specific receptor called ERBB2 which is found in cochlear support cells. (regenerativemedicine.net)
  • In the lab, fruit flies lay their fertilized eggs in a mixture of agar, molasses, cornmeal, and yeast. (asu.edu)
  • 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)
  • 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)
  • 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)
  • Transmission electron microscopes are designed to examine the internal structures of a cell, whereas a scanning electron microscope only allows visualization of the surface of a structure. (dokumen.pub)
  • Chapter 3 1 Figure 3.7 Plant cells have plasmodesmata, a cell wall, a large central vacuole, chloroplasts, and plastids. (dokumen.pub)
  • Body cells break down sugars to provide ATP to do the work necessary for exercise, such as muscle contractions. (dokumen.pub)
  • 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)
  • 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)