I Wilmut

..Improvements in the efficiency may depend upon understanding those mechanisms in the early embryo that establish the precise chromatin structure that governs development...

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..Finally, cells capable of differentiation into any of the tissues of a patient will provide treatment for diseases reflecting damage to a specific cell population that neither repairs nor replaces itself...

..When looking to the future, delegates to this meeting should take pride in what science continues to contribute...

..When a nucleus is placed in oocyte cytoplasm, the changes in chromatin structure that govern differentiation can be reversed, and the nucleus can be made to control development to term...

..5-fold increase) when compared with the results before the modifications. A 2.4-fold increase in overall efficiency was achieved from the oocyte to morula/blastocyst stages...

..Although three of these perished soon after birth, one survived for 12 days. These data show that lambs carrying targeted gene deletions can be generated by nuclear transfer...

..Live offspring were derived from both oocyte strains using the latter, whereas a single living mouse was cloned from activated B6CBAF1 cytoplasts...

..Lastly, the present study shows for the first time a comparably effective but novel alternative for pregnancy maintenance in the pig involving the co-transfer of parthenote embryos...

..This highlights the potential benefits of epigenetic diagnostic screening in developing embryo procedures...

..This culture system may provide a valuable approach for studying the regulation of early follicular development and for production of oocytes for nuclear/embryo transfer, but further work is required...

..These deficiencies are not linked to gross defects in chromosome number...

..No fetuses survived beyond 40 days of development, however, showing that although these cells could be substantially reprogrammed, they were not fully competent for nuclear transfer...

..3% of transferred embryos developed to term. These results indicate that GV material is essential for nucleus remodeling after nuclear transfer...

..The rederived lines had the same proliferative capacity and rate of telomere shortening as the donor cell lines, suggesting that these are innate, genetically determined, properties that are conserved by nuclear transfer...

..In this report, we demonstrate that live lambs can be produced from zona-free IVF embryos. We are pursuing this method as a prerequisite to developing viral vector co-culture delivery strategies...

..0% of transferred embryos developed to term). These observations establish that a zona-free cloning approach is possible in the mouse, although further research is required to increase the efficiency...

..Because controlled hypothesis testing of clone fidelity or clone health may not be possible, meticulous documentation of such observational evidence is a valuable contribution to the field...

..RNAi-mediated knockdown of this novel transcript resulted in embryonic developmental arrest at the late morula stage, suggesting an essential role for this isoform in sheep blastocyst formation...

..However, no improvement in blastocyst development was observed. Using fetal fibroblasts as nuclear donor cells, a live cloned piglet was produced in a pregnancy that was maintained by cotransfer of parthenogenetic embryos...

..Similarly, no differences were found regarding the onset of transcription of Dnmt1s, Nanog, and Fgf4 genes...

..Key problems hindering further progress are addressed...

..In addition, the study has confirmed that the changes in cloned lamb nephropathy are established by day 85 of development...

..These results also demonstrate that the inbred ES cell line, HM-1, can be used to produce viable cloned mice, although less efficiently than most heterozygous ES cell lines...

..0 kV/cm DC. Approximately 84% of parthenogenetic blastocysts yielded by this protocol were diploid, implying a potential for further in vivo development...

..This has potential application in the production of organs for transplantation to humans, studies of human genetic disease and basic research in to the control of gene expression and function...

..Human reproductive cloning is unethical, but the production of cells from cloned embryos could offer many potential benefits. So, can human cloning be made safe?..

..M16 medium is superior for culture of nuclear transfer embryos and low oxygen concentration with CZB medium during culture shows no benefit on development of cloned embryos...

..Our results suggest that the murine demethylation process is facilitated either by a sperm-derived factor or by male pronuclear chromatin composition...

..Parthenote fetuses collected 21 and 30 days post estrus were morphologically normal but significantly smaller and lighter than fertilized controls (p < 0.01). IVM pig parthenotes stopped development around 31 days post estrus...

..This provides a methodology for studying the de-differentiation of somatic cells that can potentially lead to an efficient way of reprogramming somatic cells to a pluripotent state without genetically altering them...

..Refinements of this procedure will make it possible to produce pluripotent human cell lines without use of an embryo. There are profound scientific and social implications of this research...

..Finally, we will summarize the emerging principles which appear to govern nuclear reprogramming and production of clones, and will consider the application of nuclear transfer to the rat...

..Thus, both remodeling of DNA and epigenetic reprogramming appear critical for development of both fertilized and nuclear transfer embryos...

..Although the underlying mechanisms remain to be determined, our data indicate that somatic cell nuclear transfer procedures can lead to epigenetic deregulation at imprinted loci...

..This represents another sequential step in the generation of therapeutic grade stem cells with reduced risk of zoonotic pathogen transmission...