Identification of two insulin-like growth factor IIs in the Japanese eel, Anguilla japonica: cloning, tissue distribution, and expression after growth hormone treatment and seawater acclimation.
To better understand the role of IGFs in Japanese eel, Anguilla japonica, we cloned insulin-like growth factor-II (IGF-II) cDNAs and examined their mRNA expression in several tissues. Two eel IGF-II cDNAs, eIGF-II-1 and eIGF-II-2, were cloned from the liver. A signal peptide and a mature peptide of both preproIGF-IIs were composed of 47 amino acids (aa) and 69 aa, but they differed at 17 aa and 13 aa, respectively. The E domain of eIGF-II-1 was 49 aa longer than that of eIGF-II-2, and differed at 22 aa within 52 aa. The highest eIGF-II-1 and II-2 mRNA levels were observed in the liver, with detectable levels also found in all tissues examined. The eIGF-II-1 mRNA levels in the liver, heart, and muscle were higher in females than in males, whereas those in the stomach and intestine were lower in the females. The eIGF-II-2 mRNA levels in the liver and swim-bladder were also higher in females than in males whereas those in the stomach, spleen, and intestine were lower in the females. The eIGF-II-1 mRNA levels in the liver were higher in large compared to small glass eels, while the eIGF-II-2 mRNA levels did not correlate with body weight. Both eIGF-II mRNA levels in the liver increased after eel GH treatments in vivo and in vitro. No differences in both eIGF-II mRNA levels were observed in the gills, liver, stomach and whole kidney between seawater- and freshwater-reared eels.
Moriyama
Shunsuke
S
School of Fisheries Sciences, Kitasato University, Sanriku, Iwate 022-0101, Japan. morisuke@kitasato-u.ac.jp
Yamaguchi
Kiyoko
K
Takasawa
Tomomi
T
Chiba
Hiroaki
H
Kawauchi
Hiroshi
H
D000064:Acclimatization / Q000502:physiology*; D000811:Anguilla; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D029941:Fish Proteins / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology*; D007335:Insulin-Like Growth Factor II / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D009928:Organ Specificity / Q000502:physiology; D012623:Seawater; D012727:Sex Characteristics
D018076:DNA, Complementary; D029941:Fish Proteins; D007335:Insulin-Like Growth Factor II