title: Glucose metabolism during bovine preimplantation development: analysis of gene expression in single oocytes and embryos.
abstract: Glucose metabolism of the bovine embryo is low during the first cleavages and increases sharply after the major resumption of the genome (8-16 cells). The mRNA level for genes involved in glucose metabolism was tested by RT-PCR on individual oocytes and embryos at different stages of development. These genes were: glucose transport GLUT-1, hexokinase (HK), glucose-6-phosphatase-dehydrogenase (G6PDH), and glucose-phosphate-isomerase (GPI); actin was used as a reference transcript. RT-PCR results revealed three types of oocytes or embryos: positive with a PCR signal for each transcript considered, nul with no signal for any transcript, and heterogeneous with a PCR signal for some transcripts and none for others. The number of nul and heterogeneous samples was higher for slow than for fast-cleaving embryos (81% vs. 36%), and the proportion of positive embryos increased significantly at the 16-cell and morula stages (P < 0.002), suggesting a correlation between mRNA content and developmental capacity. In positive embryos, GLUT-1 level was reduced by half during maturation and fertilization. Actin and hexokinase mRNA levels decreased during the first cleavages, but significantly increased at the 16-cell and morula stages, respectively. GPI transcript remained stable throughout development, whereas there was a significant rise for G6PDH at the 4-cell stage, perhaps due to a polyadenylation process. Finally, the absence or decrease in intensity of several transcripts at the blastocyst stage suggests suboptimal culture conditions.
authors.affiliation: Unité des Sciences Vétérinaires, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: A S
authors.initials: AS
authors.lastname: Lequarre
authors.forename: B
authors.initials: B
authors.lastname: Grisart
authors.forename: B
authors.initials: B
authors.lastname: Moreau
authors.forename: N
authors.initials: N
authors.lastname: Schuurbiers
authors.forename: A
authors.initials: A
authors.lastname: Massip
authors.forename: F
authors.initials: F
authors.lastname: Dessy
mesh_terms: D000199:Actins / Q000235:genetics; D000818:Animals; D002417:Cattle; D004622:Embryo, Mammalian / Q000378:metabolism*; D047108:Embryonic Development; D005260:Female; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D005956:Glucose-6-Phosphate Isomerase / Q000235:genetics; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics; D006593:Hexokinase / Q000235:genetics; D009004:Monosaccharide Transport Proteins / Q000235:genetics; D009865:Oocytes / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D014158:Transcription, Genetic
chemical_list: D000199:Actins; D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; D005954:Glucosephosphate Dehydrogenase; D006593:Hexokinase; D005956:Glucose-6-Phosphate Isomerase; D005947:Glucose