Comparative genomics approach to the expression of figalpha, one of the earliest marker genes of oocyte differentiation in medaka (Oryzias latipes).
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.
Kanamori
Akira
A
Division of Biological Sciences, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan. kanamori@bio.nagoya-u.ac.jp
Toyama
Keiko
K
Kitagawa
Sachiko
S
Kamehara
Aya
A
Higuchi
Tomoya
T
Kamachi
Yusuke
Y
Kinoshita
Masato
M
Hori
Hiroshi
H
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
D051792:Basic Helix-Loop-Helix Proteins; D005819:Genetic Markers