title: Comparative genomics approach to the expression of figalpha, one of the earliest marker genes of oocyte differentiation in medaka (Oryzias latipes).
abstract: We analyzed molecular cascades of sex differentiation in medaka gonads by examining the transcriptional regulation of the oocyte-expressed gene, figalpha. We first confirmed that figalpha is one of the earliest marker genes of oocyte differentiation by quantitative RT-PCR and in situ hybridization. Expression of putative figalpha target genes, zpc4 and zpb, followed that of figalpha. A meiosis-specific gene, scp3, showed expression temporally and spatially similar to figalpha. To characterize the cis-regulatory sequences of figalpha, we compared genomic organizations of vertebrate figalpha genes. Both number and sequence homology of the C-terminal exons showed divergence, suggesting their less important roles. In the frog, Xenopus tropicalis, and in many teleosts, figalpha is located between hexokinase 2 and beta-adducin. We compared this genomic region for potential cis-regulatory elements and found no DNA stretches with high homology. In spite of this lack of sequence similarities, fluorescent protein transgenes surrounded with figalpha flanking sequences from the compact genomes of fugu or Tetraodon faithfully reproduced the endogenous expression of figalpha in the medaka oocytes, indicating conserved regulatory mechanisms.
authors.affiliation: Division of Biological Sciences, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan. kanamori@bio.nagoya-u.ac.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Kanamori
authors.forename: Keiko
authors.initials: K
authors.lastname: Toyama
authors.forename: Sachiko
authors.initials: S
authors.lastname: Kitagawa
authors.forename: Aya
authors.initials: A
authors.lastname: Kamehara
authors.forename: Tomoya
authors.initials: T
authors.lastname: Higuchi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kamachi
authors.forename: Masato
authors.initials: M
authors.lastname: Kinoshita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hori
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D051792:Basic Helix-Loop-Helix Proteins / Q000737:chemistry / Q000235:genetics*; D002454:Cell Differentiation / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005819:Genetic Markers; D023281:Genomics; D017403:In Situ Hybridization; D008297:Male; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism*; D009990:Oryzias / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D005819:Genetic Markers