title: A retrospective model of oocyte competence: global mRNA and housekeeping transcripts are not associated with in vitro developmental outcome.
abstract: SummaryOocyte developmental competence depends on maternal stores that support development throughout a transcriptionally silent period during early embryogenesis. Previous attempts to investigate transcripts associated with oocyte competence have relied on prospective models, which are mostly based on morphological criteria. Using a retrospective model, we quantitatively compared mRNA among oocytes with different embryo development competence. A cytoplasm biopsy was removed from in vitro matured oocytes to perform comparative analysis of amounts of global polyadenylated (polyA) mRNA and housekeeping gene transcripts. After parthenogenetic activation of biopsied oocytes, presumptive zygotes were cultured individually in vitro and oocytes were classified according to embryo development: (i) blocked before the 8-cell stage; (ii) blocked between the 8-cell and morulae stages; or (iii) developed to the blastocyst stage. Sham-manipulated controls confirmed that biopsies did not alter development outcome. Total polyA mRNA amounts correlate with oocyte diameter but not with the ability to develop to the 8-cell and blastocyst stages. The last was also confirmed by relative quantification of GAPDH, H2A and Hprt1 transcripts. In conclusion, we describe a novel retrospective model to identify putative markers of development competence in single oocytes and demonstrate that global mRNA amounts at the metaphase II stage do not correlate with embryo development in vitro.
authors.affiliation: USP-FZEA - Departamento de Ciências Básicas, Rua Duque de Caxias Norte, 225, Pirassununga-SP Brazil. fernandobiase@hotmail.com
authors.forename: Fernando Henrique
authors.initials: FH
authors.lastname: Biase
authors.forename: Lúcia
authors.initials: L
authors.lastname: Martelli
authors.forename: Giovana Krempel Fonseca
authors.initials: GK
authors.lastname: Merighe
authors.forename: Weruska Karyna Freitas
authors.initials: WK
authors.lastname: Santos Biase
authors.forename: Moyses
authors.initials: M
authors.lastname: Miranda
authors.forename: Lawrence Charles
authors.initials: LC
authors.lastname: Smith
authors.forename: Flávio Vieira
authors.initials: FV
authors.lastname: Meirelles
mesh_terms: D000818:Animals; D003593:Cytoplasm / Q000378:metabolism; D004622:Embryo, Mammalian / Q000378:metabolism; D047108:Embryonic Development; D005260:Female; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D023121:RNA, Messenger, Stored / Q000378:metabolism*
chemical_list: D023121:RNA, Messenger, Stored