Oocytes maturing

This intermediate MAPK activator (MAPK kinase, MAPKK) is a 45 kDa phosphoprotein capable of phosphorylating MAPK on serine/threonine and tyrosine residues (Matsuda et al., 1992 Nakielny et al., 1992a Kosako et al., 1993). Like MAPK, the activity of MAPKK is regulated by phosphorylation. During oocyte maturation MAPKK is phosphorylated on threonine residues (Kosako et al., 1992), and this phosphorylation is required for its activity (Ahn et al., 1991 Gomez and Cohen, 1991 Kosako et al., 1992 Matsuda et al., 1992). MPF can activate both MAPKK and MAPK in vitro, with the activation of MAPK lagging behind that of MAPKK however, MPF cannot activate either purified MAPKK or MAPK that has been dephosphorylated by phosphatases (Matsuda et al., 1992). MAPKK and MAPK are therefore believed to function downstream of MPF (Fig. 3). 

Hashimoto, N., and Kishimoto, T. (1988). Regulation of meiotic metaphase by a cytoplasmic maturation-promoting factor during mouse oocyte maturation. Dev. Biol. 126 242-252. 

Minshull, J., Murray, A., Colman, A., and Hunt, T. (1991). Xenopus oocyte maturation does not require new cyclin synthesis. J. Cell Biol. 114 767-772. 

Posada, J., Sanghera, J Pelech, S., Aebersold, R., and Cooper, J. A. (1991). Tyrosine phosphorylation and activation of homologous protein kinases during oocyte maturation and mitogenic activation of fibroblasts. Mol. Cell. Biol. 11 2517-2528,... 

Sagata, N., Daar, I., Oskarsson, M Showalter, S. D and Vande Woude, G. F. (1989a). The product of the mos proto-oncogene as a candidate initiator for oocyte maturation. Science 245 643-646. 

McGrew, L. L., Dworkin-Rastl, E., Dworkin, M. B and Richter, J. D. (1989). Poly(A) elongation during Xenopus oocyte maturation is required for translational recruitment and is mediated by a short sequence element. Genes Dev. 3 803-815. 

FIG. 1. Schematic diagram of early Xenopus development. The figure shows relative levels of MPF (cyclin B/Cdc2) activity from the beginning of oocyte maturation until after fertilization. 

Freeman RS, Meyer AN, Li J,DonoghueDJ 1992 Phosphorylation of conserved serine residues does not regulate the ability of mosxe protein kinase to induce oocyte maturation or function as cytostatic factor. J Cell Biol 116 725—735... 

Lohka MJ, Hayes MK, Mailer JL 1988 Purification of maturation-promoting factor, an intracellular regulator of early mitotic events. Proc Natl Acad Sci USA 85 3009—3013 Mailer JL, Butcher FR, Krebs EG 1979 Early effects of progesterone on levels of cyclic adenosine 3 5 -monophosphate in Xenopus oocytes. J Biol Chem 254 579-582 Masui Y 1967 Relative roles of the pituitary, follicle cells, and progesterone in the induction of oocyte maturation in Ranapipiens. J Exp Zool 166 365-375 Masui Y, Markert CL 1971 Cytoplasmic control of nuclear behavior during meiotic maturation of frog oocytes. J Exp Zool 177 129-145... 

Roy LM, Haccard O, Izumi T, Lattes BG, Lewellyn AL, Mailer JL 1996 Mos proto-oncogene function during oocyte maturation in Xenopus. Oncogene 12 2203-2211 Sagata N 1997 What does Mos do in oocytes and somatic cells Bioessays 19 13-21... 

Schwab MS, Kim SH, Terada N et al 1999 The p70(S6K) controls selective mRNA translation during oocyte maturation and early embryogenesis in Xenopus laevis. Mol Cell Biol 19 2485— 2494... 

Korotchenko and coworkers detected PG-like compounds in five starfish from the Sea of Japan Asterias amurensis, Distolasterias nippon, Evasterias r. tabulata, Lysastrosoma anthosticta, and Patina pectinifera [189]. Perry and Epel showed that Pisaster ochraceous homogenates were able to oxidize AA [190]. Early studies on oocyte maturation in starfish suggested that HETE s might play a role [195]. Two compounds, 12- and 15-HETE, were able to induce oocyte maturation. Subsequent work showed that the activity was actually due to 8-HETE (33), which was a minor contaminant of both HETE preparations [196]. The 8R enantiomer of this compound (33) and 8R-HEPE (32) were also isolated from the aqueous extracts of Patiria miniata from the Gulf of California [197],... 

R-HETE is a very potent and selective inducer of oocyte maturation [196, 199]. 8S-HETE does not show this activity. The allene oxide hydrolysis products and the hydroperoxide lyase products were not active in promoting oocyte maturation [200]. 

Replacement of the famesyl group by lipid analogues could be performed for full length Ras proteins in vitro by means of the enzyme famesyltrans-ferase. When such partially modified Ras constructs were applied in Xenopus oocytes the cellular machinery completed modification (endoprotease activity, carboxymethylation and palmitoylation). In these cases the H-Ras famesyl group could be stripped off most of its isoprenoid features that distinguish it from a fatty add without any apparent effect on its ability to induce oocyte maturation and activation of mitogen-activated protdn kinase In contrast, replacement by the less hydrophobic isoprenoid geranyl causes severely delayed oocyte activation. 

Tokumoto, T. et al. Regulated interaction between polypeptide chain elongation factor-1 complex with the 26S proteasome during Xenopus oocyte maturation. BMC Biochem 2003, 4, 6. 

Schmitt A, Gutierrez GJ, Lenart P, Ellenberg J, Nebreda AR (2002) Histone H3 phosphorylation during Xenopus oocyte maturation regulation by the MAP kinase/p90Rsk pathway and uncoupling from DNA condensation. EEBS Lett 518(l-3) 23-28... 

Goldfish Carassius F M Oocyte-maturation- J1 Feeding Sorensen and... 

Oogenesis is the process of ovum formation and maturation. During oogenesis, primordial germ cells are formed, which become oogonia and subsequently oocytes in the fetus. In the adult, oocytes mature into ova, which contain the nutrients that support the early embryo s energy requirements (Wasserman, 1996 Wasserman Albertini, 1996). 

Other possible ovarian regulators include tumour necrosis factor-alpha, catecholaminergic input, luteinization inhibitor, gonadotrophinbinding inhibitors, oocyte maturation inhibitor and the ovarian renin-angiotensin system. Ovarian renin-angiotensin has been detected in follicular fluid (Lightman et al., 1989). 

Receptor sites for angiotensin II, the main active peptide of the renin-angiotensin system, have been found in the ovaries (Lightman et al., 1989). Ovarian renin-angiotensin may also have an autocrine role in angiogenesis, steroidogenesis and oocyte maturation. Inhibin is produced by the ovarian follicle and corpus luteum (Tsonis et al.,... 

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