title: The medaka midblastula transition as revealed by the expression of the paternal genome.
abstract: At midblastula transition (MBT), zygotic gene transcription is activated, cells become motile and cell division becomes asynchronous. The onset of the medaka (Oryzias latipes) MBT was examined using expressed sequence tag (EST) markers. Among 187 randomly chosen medaka EST markers, 33 EST markers and two genes (eIF-4C and hsc70) showed polymorphisms in terms of insertion/deletions or restriction sites between the two parental inbred strains, one from the northern Japanese population and the other from the southern Japanese population. There was no evidence of zygotic expression of these EST markers before Stage 10 (early blastula stage), whereas expression of 12 genes was found from Stage 11 on. These results suggest that the medaka MBT in terms of first time transcription of paternal genes in the life of the embryo begins at Stage 11 (late blastula stage).
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa-no-ha 5-1-5, Kashiwa, Chiba 277-8572, Japan. kk17501@mail.ecc.u-tokyo.ac.jp
authors.forename: Kouichi
authors.initials: K
authors.lastname: Aizawa
authors.forename: Atsuko
authors.initials: A
authors.lastname: Shimada
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Naruse
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mitani
authors.forename: Akihiro
authors.initials: A
authors.lastname: Shima
mesh_terms: D000818:Animals; D036703:Blastula / Q000378:metabolism*; D020869:Gene Expression Profiling; D009990:Oryzias / Q000196:embryology*