title: Characterization of Stra8 in Southern catfish (Silurus meridionalis): evidence for its role in meiotic initiation.
abstract: BACKGROUND
  RA (retinoic acid) signal pathway has been proved to be required for germ cell meiotic initiation in mammals, aves and amphibians. Stra8 (Stimulated by retinoic acid gene 8) is an important factor in RA signal pathway. However, the role of RA and Stra8 in germ cell meiotic initiation in teleosts is poorly characterized.
  
  
  RESULTS
  In this study, the full length cDNA of Stra8 was cloned from Southern catfish (Silurus meridionalis), and its spatio-temporal expression profiles were analyzed. The Stra8 cDNA (1606 bp) includes 163 bp 5'-UTR (untranslated region), 456 bp 3'-UTR, and an ORF (open reading frame) of 987 bp, encoding a polypeptide of 328 aa. Phylogenetic analysis revealed its existence in some primitive teleosts, such as Siluriformes and Salmoniformes. Tissue distribution analysis by RT-PCR showed that Stra8 is specifically expressed in gonads. By real-time PCR, in situ hybridization and immunohistochemistry, the highest expression level of Stra8/Stra8 was detected in 50 and 130 dah (day after hatching), the premeiotic stage of germ cells in XX and XY gonads, respectively.
  
  
  CONCLUSIONS
  Our results suggest that Stra8 might be involved in germ cell meiotic initiation in S. meridionalis as it did in tetrapods.
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China.
authors.forename: Ranran
authors.initials: R
authors.lastname: Dong
authors.forename: Shijie
authors.initials: S
authors.lastname: Yang
authors.forename: Jing
authors.initials: J
authors.lastname: Jiao
authors.forename: Tingru
authors.initials: T
authors.lastname: Wang
authors.forename: Hongjuan
authors.initials: H
authors.lastname: Shi
authors.forename: Linyan
authors.initials: L
authors.lastname: Zhou
authors.forename: Yaoguang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Deshou
authors.initials: D
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002397:Catfishes / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D005260:Female; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005399:Fishes / Q000145:classification / Q000235:genetics / Q000378:metabolism; D005854:Germ Cells / Q000166:cytology* / Q000378:metabolism*; D006066:Gonads / Q000166:cytology / Q000378:metabolism; D008297:Male; D008540:Meiosis; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D014212:Tretinoin / Q000378:metabolism; D020506:Untranslated Regions
chemical_list: D029941:Fish Proteins; D020506:Untranslated Regions; D014212:Tretinoin