title: Individual bovine in vitro embryo production and cumulus cell transcriptomic analysis to distinguish cumulus-oocyte complexes with high or low developmental potential.
abstract: Studying cumulus cell (CC) transcriptome is of great interest as it could provide a noninvasive method to assess oocyte quality. In cattle, the search for quality markers has not been done with cumulus-oocyte complexes (COCs) cultured individually from maturation to blastocyst stage. Here, differences between high- and low-potential COCs were examined by transcriptomic analysis of CC biopsies obtained from COCs of 2 to 6 mm follicles (n = 249; eight replicates) before individual in vitro maturation, fertilization, and culture until Day 8 after fertilization. Each COC was individually tracked and categorized based on his fate: embryo at blastocyst stage (CC-Blast) or embryo arrested at 2- to 8-cell stage (CC-2-8-cells). Average blastocyst rates were 27.7% for individual culture and 31.2% for group control (not significantly different). For transcriptomic analysis, five cumulus biopsies per replicate were pooled for each fate. Three CC replicates underwent transcriptomic analysis using RNA microarray assay. Some clear differences in gene expression between the CC-Blast and the CC-2-8-cell groups were identified. Considering a 1.5-fold change (P < 0.05), 68 genes were differentially expressed between the CC-Blast and CC-2-8-cells. Quantitative reverse transcription-polymerase chain reaction validations were performed for 12 selected genes: six upregulated genes for each COC fate. Higher expression of 1-acylglycerol-3-phosphate O-acyltransferase 9 (AGPAT9) (lipid metabolism), Chloride intracellular channel 3 (CLIC3), Keratin 8 (KRT8), and Lumican (LUM) (molecular transport) was observed in CC-2-8-cells (P < 0.05). The CC-Blast fate analysis revealed a significantly higher expression of Glycine amidinotransferase (L-arginine:glycine amidinotransferase) (GATM) (posttranslational modification, amino acid metabolism, and free radical scavenging). This newly identified set of genes could provide new markers to distinguish COCs associated with good quality embryos from COCs with limited developmental potential.
authors.affiliation: Centre de Recherche en Biologie de la Reproduction, Faculté des Sciences de l'Agriculture et de l'Alimentation, Département des Sciences Animales, Université Laval, Québec, Quebec, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Bunel
authors.affiliation: Gamete Research Center, Laboratory for Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium.
authors.forename: E P
authors.initials: EP
authors.lastname: Jorssen
authors.affiliation: Gamete Research Center, Laboratory for Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Merckx
authors.affiliation: Gamete Research Center, Laboratory for Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium.
authors.forename: J L
authors.initials: JL
authors.lastname: Leroy
authors.affiliation: Gamete Research Center, Laboratory for Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium.
authors.forename: P E
authors.initials: PE
authors.lastname: Bols
authors.affiliation: Centre de Recherche en Biologie de la Reproduction, Faculté des Sciences de l'Agriculture et de l'Alimentation, Département des Sciences Animales, Université Laval, Québec, Quebec, Canada. Electronic address: Marc-Andre.Sirard@fsaa.ulaval.ca.
authors.forename: M A
authors.initials: MA
authors.lastname: Sirard
mesh_terms: D000818:Animals; D017209:Apoptosis; D001755:Blastocyst / Q000502:physiology; D002417:Cattle / Q000196:embryology*; D002452:Cell Count; D054885:Cumulus Cells / Q000737:chemistry* / Q000502:physiology*; D046149:Embryo Culture Techniques; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary*; D020869:Gene Expression Profiling / Q000662:veterinary*; D020287:In Situ Nick-End Labeling; D059471:In Vitro Oocyte Maturation Techniques / Q000662:veterinary; D046228:Microarray Analysis; D009865:Oocytes / Q000502:physiology*; D012313:RNA / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary
chemical_list: D012313:RNA
keywords: Cumulus biopsy; Individual culture; Oocyte competence; Transcriptome