Embryo cells oocyte activation

Cuthbertson KS, Whittingham DG, Cobbold PH 1981 Free Ca2+ increases in exponential phases during mouse oocyte activation. Nature 294 754—757 Day ML, Johnson MH, Cook DI 1998 A cytoplasmic cell cycle controls the activity of a K+ channel in pre-implantation mouse embryos. EMBO J 17 1952—1960 Flach G, Johnson MH, Braude PR, Taylor RA, Bolton VN 1982 The transition from maternal to embryonic control in the 2-cell mouse embryo. EMBO J 1 681-686 Howlett SK 1986 A set of proteins showing cell cycle-dependent modification in the early mouse embryo. Cell 45 387-396... 

One approach to overcome the transplant rejection of human embryonic stem (ES) cells is to derive them by nuclear transfer of the patients own cells. In the absence of an efficient protocol for human somatic cell nuclear transfer (SCNT), several critical steps must be optimized, namely reprogramming time, activation method, and in vitro culture conditions. Reprogramming time was defined as the time between cell fusion and oocyte activation to permit proper embryonic development. A 2 h reprogramming time led to 25% of the recon-stracted embryos developing to blastocysts. In SCNT, in the absence of sperm-mediated activation, an artificial stimulus is needed to initiate embryo development. Addition of 10 pM ionophore for 5 min, and incubation with 2.0 mM 6-dimethyl aminopurine for 4 h, was the most efficient chemical activation protocol for human SCNT embryos. Encouragingly, inefficiencies in embryo culture have been overcome by supplementing... 

Exit from Mil arrest of the ovulated oocyte is accomplished by fertilization with sperm, and is commonly referred to as oocyte activation . This activation is triggered by intracellular calcium oscillations induced by fertilization [17]. Due to an absence of fertihzation by sperm in SCNT embryos, reconstructed oocytes must be stimulated artificially to fuse between donor cells and oocytes, and to initiate embryo development. A variety of chemical, physical and mechanical agents have been shown to induce the activation of reconstructed oocytes, with different efficiencies. 

Research gi oup Oocyte maturation Method of nuclei transfer Method of oocyte activation Donor ceil type Number of embryos transferred Time of embryo culture prior to transfer Donor cell culture conditions... 

Choi, T., Aoki, E, Mori, M., Yamashita, M., Nagahama, Y., and Kohmoto, K. (1991). Activation of p34nfc2 protein kinase activity in meiotic and mitotic cell cycles in mouse oocytes and embryos. Development 113 789-795. 

The first cell cycle of the mouse embryo differs in many respects from the second and the following cell cycles. It is characterized by a long Gl phase that starts after the penetration of the spermatozoon or artificial activation of the oocyte. During this period the chromatin of the oocyte completes the second meiotic division and forms the female pronucleus. At the same time, in the fertilized egg, the highly condensed chromatin of the sperm nucleus decondenses and sperm-specific proteins, protamines, are replaced by histones. After the initial sperm chromatin... 

The metaphase arrest in vertebrate oocytes is maintained by cytostatic factor activity (CSF Masui Markert 1971). CSF was first demonstrated in amphibian oocytes by transferring cytoplasm from metaphase II (M II)-arrested oocytes into one blastomere of a two-cell embryo. The injected blastomere was arrested in M phase while the non-injected blastomere continues to cleave (Masui Markert... 

Borsuk E, Manka R 1988 Behavior of sperm nuclei in intact and bisected metaphase II mouse oocytes fertilized in the presence of colcemid. Gamete Res 20 365-376 Ciemerych MA 1995 Chromatin condensation activity and cortical activity during the first three cell cycles of mouse embryo. Mol Reprod Dev 41 416—424 Ciemerych MA, Kubiak JZ 1999 Transient reactivation of CSF in parthenogenetic one-cell mouse embryos. Biol Cell 91 641—647... 

Winston N J 1997 Stability of cyclin B protein during meiotic maturation and the first mitotic cell division in mouse oocytes. Biol Cell 89 211-219 Winston NJ, Maro B 1995 Calmodulin-dependent protein kinase II is activated transiently in ethanol-stimulated mouse oocytes. Dev Biol 170 350-352 Winston NJ, Bourgain-Guglielmetti F, Ciemerych MA et al 2000 Early development of mouse embryos null mutant for the cyclin A2 gene occurs in the absence of maternally derived cyclin A2 gene products. Dev Biol 223 139-153... 

Pig cloning will thus have a marked impact on tire optimization of meat production and xenohansplantation. To clone pigs from differentiated cells, tire nuclei of porcine Sus scrofa) fetal fibroblasts were injected into enucleated oocytes, and the development was induced by electro activation. The transfer of 110 cloned embryos to foiu sunogate mothers produced an apparently normal female piglet. The clonal provenance of the piglet was indicated by her coat color and confirmed by DNA microsatellite analysis. 

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