Differential transcription of laminin subunits in mouse oocyte, preimplantation embryo and parthenogenote

Abstract

To study the regulation of laminin expression in preimplantation embiyogenesis and oogenesis of mouse embryo，the transcriptions of laminin subunits, A, Bl, and B2, were examined by polymerase chain reaction coupled with reverse transcription. And the expression of laminin subunits of parthenogenesised embryo was compared with that of normally developed embryo to examine whether they are imprinted in maternal genome. The mRNA of laminin Bl subunit was detected from the germinal vesicle stage oocyte, however, laminin B2 and laminin A mRNAs could not be detected in all stages of oogenesis. Maternal laminin Bl mRNA was degraded and embryonal transcripts of laminin Bl accumulation started at the two-cell stage. The laminin B2 mRNA was detected after the four-cell stage and laminin A mRNA was expressed at the blastocyst. Therefore, the three genes of laminin subunits are asynchronously transcribed during mouse embryogenesis and oocyte maturation. On the other hand, the parthe-nogenetic embryo cultured to the blastocyst expressed all three subunits of laminin mRNAs as the nonnally developed embryo did. This indicates that the laminin genes are not imprinted in the mouse maternal genome.