RNA and protein synthesis requirements for the resumption of meiosis in rabbit oocytes : the role of cumulus cells

Abstract

Summary ― In vitro maturation of rabbit cumulus-enclosed oocytes was fully inhibited in aamanitin-(100 8 g/ml) and cycloheximide-(5 pg/ml) supplemented media.The inhibition was reversible and substantially reduced by delaying the addition of a-amanitin (2h) or cycloheximide (3 h).In contrast, both drugs did not inhibit germinal vesicle breakdown in denuded oocytes.Co-culture of granulosa cells (1 x 10 6 /ml) with denuded oocytes did not substitute for an intact cumulus.The data presented here suggest that the resumption of meiosis in rabbit cumulus-enclosed oocytes is dependent upon early transcriptional and translational events which probably occur within the cumulus cells.oocyte maturation -cumulus oophorus ― transcription -translation -rabbit Résumé ― Synthèse d'ARN et de protéines nécessaires à la reprise de la méiose : rôle des cellules du cumulus oophorus. La reprise de la méiose in vitro d'ovocytes de lapins inclus dans leur cumulus oophorus est complètement inhibée par l'a-amanitine (100 pg/ml) et le cycloheximide (5 pglmo. L'inhibition est réversible et fortement diminuée si l'on retarde le traitement par l'aamanitine (2 h) ou la cycloheximide (3 h).Au contraire, les deux inhibiteurs n'empêchent pas la rupture de la vésicule germinale d'ovocytes dénudés (sans cumulus oophorus).Des cellules de la granulosa (f0!lml) en coculture avec des ovocytes dénudés ne remplacent pas un cumulus oophorus intact. Les résultats présentés suggèrent que la reprise de la méiose dans des ovocytes de lapins inclus dans le cumulus oophorus est sous la dépendance de phénomènes de transcription et de traduction survenant probablement dans les cellules périovocytaires. maturation de l'ovocyte -cumulus oophorus ― transcription -traduction -lapin

Proteins in oocytes from calves and adult cows before maturation: relationship with their development capacity

“…The effect of follicular size has recently been reported to affect the developmental potential of the oocytes (Tan and Lu, 1990;Pavlok et al, 1992), but unfortunately is not related to the appearance of a visible specific product with the methodology used here. However, the relative amount of some proteins (143, 137, 60, 58, 52 and 27 kDa) seems to increase and some large molecular weight bands are much less apparent (180,158,131,71 Tan and Lu (1990) (Motlik et al, 1989). Furthermore, the low rate of development of calf oocytes and denuded cow oocytes could result from abnormalities in maturation divisions.…”

Protein kinases influence bovine oocyte competence during short-term treatment with recombinant human follicle stimulating hormone

“…This calcium release may be related to the early transcriptional and translation events that are required for the stimulatory phase of gonadotrophin-mediated GVBD in cultured oocytes (Motlik et al 1989, Farin & Yang 1994. Furthermore, IP3 can also be transferred from the cumulus cells into the oocyte via gap junctions to mobilize the calcium within the oocyte (Homa 1995).…”

Somatic cells and the G2 to M-phase transition in sheep oocytes

“…After radiolabelling, oocytes were washed, denuded of follicle cells and collected singly in 3 pl 10 mM Tris-HCL, ph 7.4 buffer before being lyophilised and frozen at -70°C until required for electrophoresis. Labelled oocyte polypeptides were separated on 8-15% SDS-gradient polyacrylamide gels (PAGE) as described previously (Osborn and Moor, 1983 (Bonner and Laskey, 1974) using preflashed Kodak X-Omat film at -70°C to ensure linearity and reduce background (Laskey and Mills, 1975 (Osborn and Moor, 1983 (Motlik et al, 1989 (Eppig, 1989) (Crosby et al, 1985 …”

“…However, the effectiveness of a-amatin in inhibiting meiosis depends entirely on two factors. The first is that the block must be inserted within the first 1-2 h after the initiation of maturation and the second is that the oocyte must be in junctional communication with follicle cells (Osborn and Moor, 1983 (Motlik et al, 1989 (Osborn and Moor, 1983). …”