title: Insulin-like growth factors I and II in starry flounder (Platichthys stellatus): molecular cloning and differential expression during embryonic development.
abstract: In order to elucidate the possible roles of insulin-like growth factors I and II (IGF-I and IGF-II) in the embryonic development of Platichthys stellatus, their cDNAs were isolated and their spatial expression pattern in adult organs and temporal expression pattern throughout embryonic development were examined by quantitative real-time PCR assay. The IGF-I cDNA sequence was 1,268 bp in length and contained an open reading frame (ORF) of 558 bp, which encoded 185 amino acid residues. With respect to IGF-II, the full-length cDNA was 899 bp in length and contained a 648-bp ORF, which encoded 215 amino acid residues. The amino acid sequences of IGF-I and IGF-II exhibited high identities with their fish counterparts. The highest IGF-I mRNA level was found in the liver for both sexes, whereas the IGF-II gene was most abundantly expressed in female liver and male liver, gill, and brain. The sex-specific and spatial expression patterns of IGF-I and IGF-II mRNAs are thought to be related to the sexually dimorphic growth and development of starry flounder. Both IGF-I and IGF-II mRNAs were detected in unfertilized eggs, which indicated that IGF-I and IGF-II were parentally transmitted. Nineteen embryonic development stages were tested. IGF-I mRNA level remained high from unfertilized eggs to low blastula followed by a significant decrease at early gastrula and then maintained a lower level. In contrast, IGF-II mRNA level was low from unfertilized eggs to high blastula and peaked at low blastula followed by a gradual decrease. Moreover, higher levels of IGF-I mRNA than that of IGF-II were found from unfertilized eggs to high blastula, vice versa from low blastula to newly hatched larva, and the different expression pattern verified the differential roles of IGF-I and IGF-II in starry flounder embryonic development. These results could help in understanding the endocrine mechanism involved in the early development and growth of starry flounder.
authors.affiliation: Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, Shandong, People's Republic of China.
authors.forename: Yongjiang
authors.initials: Y
authors.lastname: Xu
authors.forename: Kun
authors.initials: K
authors.lastname: Zang
authors.forename: Xuezhou
authors.initials: X
authors.lastname: Liu
authors.forename: Bao
authors.initials: B
authors.lastname: Shi
authors.forename: Cunyu
authors.initials: C
authors.lastname: Li
authors.forename: Xueying
authors.initials: X
authors.lastname: Shi
mesh_terms: D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D003001:Cloning, Molecular; D016000:Cluster Analysis; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D005432:Flounder / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D005880:Gills / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000235:genetics* / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA / Q000662:veterinary; D017385:Sequence Homology; D012727:Sex Characteristics
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II