title: Identification and characterization of a nanog homolog in Japanese flounder (Paralichthys olivaceus).
abstract: The homeodomain-containing transcription factor nanog plays a key role in maintaining the pluripotency and self-renewal of embryonic stem cells in mammals. Stem cells offered as a significant and effective tool for generation of transgenic animals and preservation of genetic resources. The molecular genetic organization and expression of nanog gene in marine fish have not been reported yet. In this study, we isolated and characterized the flounder nanog gene as a first step towards understanding the mechanism of the plurpotency of fish stem cells and develop a potential molecular marker to identify the stem cells in vivo and in vitro. Phylogenetic, gene structure and chromosome synteny analysis provided the evidence that Po-nanog is homologous to the mammalian nanog gene. Protein sequence comparison showed that flounder Nanog shared low similarity with other vertebrate orthologs except for a conserved homeodomain. Quantitative RT-PCR analysis showed that flounder nanog was maternally expressed, and the transcripts were present from the one-cell stage to the neurula stage with the peaking at blastula stage. Whole mount in situ hybridization analyses demonstrated that the transcripts were present in all blastomeres of the early embryo. Tissue distribution analysis indicated that nanog was detectable only in gonads. Further, the expression was significantly high in ovary than in testis. In situ hybridization revealed that the transcripts were located in the cytoplasm of the oogonia and oocytes in ovary, only in the spermatogonia but no spermatocytes or spermatids in testis. The promoter region was also analyzed to have several basal core promoter elements and transcription factor binding sites. All these results suggest that Po-Nanog may have a conservative function between teleosts and mammals.
authors.affiliation: College of Marine Life Science, Ocean University of China, Key Laboratory of Marine Genetics and Breeding, Ministry of Education, 5 Yushan Road, Qingdao 266003, China.
authors.forename: Jinning
authors.initials: J
authors.lastname: Gao
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Jiajun
authors.initials: J
authors.lastname: Jiang
authors.forename: Lin
authors.initials: L
authors.lastname: Fan
authors.forename: Wenji
authors.initials: W
authors.lastname: Wang
authors.forename: Jinxiang
authors.initials: J
authors.lastname: Liu
authors.forename: Quanqi
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xubo
authors.initials: X
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian; D005260:Female; D005432:Flounder / Q000196:embryology / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D000071317:Nanog Homeobox Protein; D009990:Oryzias / Q000235:genetics; D010802:Phylogeny; D017385:Sequence Homology; D029961:Zebrafish Proteins / Q000235:genetics
chemical_list: D018398:Homeodomain Proteins; D000071317:Nanog Homeobox Protein; C572119:Nanog protein, zebrafish; D029961:Zebrafish Proteins
keywords: ESC; HD; ICM; Japanese flounder (Paralichthys olivaceus); Nanog; Pluripotency; Promoter analysis; RACE; TF; TIS; TSS; UTR; embryonic stem cell; homeodomain; inner cell mass; qRT-PCR; quantitative real-time PCR; rapid amplification of cDNA ends; transcription factor; transcription initiation site; transcription start site; un-translated region