Quantification of cyclin B1 and p34(cdc2) in bovine cumulus-oocyte complexes and expression mapping of genes involved in the cell cycle by complementary DNA macroarrays.
Although high amounts of cyclin B1 mRNA are present in bovine oocytes arrested at the germinal vesicle (GV) stage, the protein is not detectable. Furthermore, there is a depletion of the stored cyclin B1 mRNA in the oocyte as follicular growth progresses. To assess the effect of follicular growth on the accumulation of M-phase promoting factor (MPF) components, mRNA and protein levels of cyclin B1 and p34(cdc2) were measured in GV oocytes collected from diverse follicle size groups (<2 mm, 3-5 mm, and >6 mm). Because oocytes collected from very small follicles have high levels of cyclin B1 mRNA, the onset of its accumulation in the oocytes was evaluated by in situ hybridization of fetal ovaries. Also, a comparative expression map of cell cycle-related genes expressed in the oocyte and cumulus cells was established using nylon-based cDNA arrays, which allowed the detection of 35 different genes transcribed mostly in oocytes. Both components of the pre-MPF complex were expressed at the mRNA level in GV oocytes, whereas p34(cdc2) was the only pre-MPF protein detected at that stage, thus indicating that meiosis resumption in bovine oocytes is differentially regulated as compared with other mammals, and meiosis resumption seems to be regulated by the translation of cyclin B1 mRNA.
Robert
Claude
C
Department of Animal Sciences, Centre de Recherche en Biologie de la Reproduction, Laval University, Québec, Canada G1K 7P4.
Hue
Isabelle
I
McGraw
Serge
S
Gagné
Dominic
D
Sirard
Marc-André
MA
D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics* / Q000378:metabolism; D002417:Cattle; D002453:Cell Cycle / Q000235:genetics; D019926:Cyclin B / Q000235:genetics* / Q000378:metabolism; D056744:Cyclin B1; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018816:Genes, cdc / Q000502:physiology*; D008540:Meiosis; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D006080:Ovarian Follicle / Q000166:cytology / Q000196:embryology / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic
D019926:Cyclin B; D056744:Cyclin B1; D012333:RNA, Messenger; D016203:CDC2 Protein Kinase