title: Sequential analysis of global gene expression profiles in immature and in vitro matured bovine oocytes: potential molecular markers of oocyte maturation.
abstract: BACKGROUND
  Without intensive selection, the majority of bovine oocytes submitted to in vitro embryo production (IVP) fail to develop to the blastocyst stage. This is attributed partly to their maturation status and competences. Using the Affymetrix GeneChip Bovine Genome Array, global mRNA expression analysis of immature (GV) and in vitro matured (IVM) bovine oocytes was carried out to characterize the transcriptome of bovine oocytes and then use a variety of approaches to determine whether the observed transcriptional changes during IVM was real or an artifact of the techniques used during analysis.
  
  
  RESULTS
  8489 transcripts were detected across the two oocyte groups, of which ~25.0% (2117 transcripts) were differentially expressed (p < 0.001); corresponding to 589 over-expressed and 1528 under-expressed transcripts in the IVM oocytes compared to their immature counterparts. Over expression of transcripts by IVM oocytes is particularly interesting, therefore, a variety of approaches were employed to determine whether the observed transcriptional changes during IVM were real or an artifact of the techniques used during analysis, including the analysis of transcript abundance in oocytes in vitro matured in the presence of α-amanitin. Subsets of the differentially expressed genes were also validated by quantitative real-time PCR (qPCR) and the gene expression data was classified according to gene ontology and pathway enrichment. Numerous cell cycle linked (CDC2, CDK5, CDK8, HSPA2, MAPK14, TXNL4B), molecular transport (STX5, STX17, SEC22A, SEC22B), and differentiation (NACA) related genes were found to be among the several over-expressed transcripts in GV oocytes compared to the matured counterparts, while ANXA1, PLAU, STC1and LUM were among the over-expressed genes after oocyte maturation.
  
  
  CONCLUSIONS
  Using sequential experiments, we have shown and confirmed transcriptional changes during oocyte maturation. This dataset provides a unique reference resource for studies concerned with the molecular mechanisms controlling oocyte meiotic maturation in cattle, addresses the existing conflicting issue of transcription during meiotic maturation and contributes to the global goal of improving assisted reproductive technology.
authors.affiliation: College of Life Science, University College Dublin, Dublin 4, Ireland. solomon.mamo@ucd.ie
authors.forename: Solomon
authors.initials: S
authors.lastname: Mamo
authors.forename: Fiona
authors.initials: F
authors.lastname: Carter
authors.forename: Patrick
authors.initials: P
authors.lastname: Lonergan
authors.forename: Cláudia Lv
authors.initials: CL
authors.lastname: Leal
authors.forename: Abdullah
authors.initials: A
authors.lastname: Al Naib
authors.forename: Paul
authors.initials: P
authors.lastname: McGettigan
authors.forename: Jai P
authors.initials: JP
authors.lastname: Mehta
authors.forename: Alexander Co
authors.initials: AC
authors.lastname: Evans
authors.forename: Trudee
authors.initials: T
authors.lastname: Fair
mesh_terms: D053959:Alpha-Amanitin / Q000494:pharmacology; D000818:Animals; D002417:Cattle / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling / Q000662:veterinary*; D018507:Gene Expression Regulation, Developmental; D008540:Meiosis; D020411:Oligonucleotide Array Sequence Analysis; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D009866:Oogenesis; D017422:Sequence Analysis, DNA
chemical_list: D053959:Alpha-Amanitin