Developmental and tissue-regulated expression of IGF-I and IGF-II mRNAs in Sparus aurata.
Recent studies have shown that homologues of the mammalian IGF-I and -II genes are also found in teleosts. We report here the cDNAs coding for IGF-I and IGF-II cloned from the gilthead seabream, Sparus aura ta. Sequence comparisons revealed that both IGFs have been well conserved among teleosts, although Sparus IGF-I is shorter bv three amino acid residues due to truncated B-and C-domains. Using the cloned cDNAs as probes, the relative expression of IGF-I and IGF-II mRNAs were assayed in different Sparus tissues. Sparus liver clearly contained the highest level of IGF-I mRNA while relatively high levels of IGF-II mRNA were found in liver, heart and gill using the ribonuclease protection assay. After GH administration the amount of IGF-I mRNA was increased by 220% in liver but no changes in IGF-II mRNA levels were detected in any tissue. We also assayed the expression of IGF-I and IGF-II in Sparus during early development. The IGF-II mRNA level was highest in larva I day after hatching and decreased thereafter. In contrast, IGF-I mRNA was detected in 1-day-old larva but there was an increase in expression in 12- and 16-day-old larva. These results demonstrated that the expression of IGF-I and IGF-II is highly regulated in teleosts and suggest that they play distinct roles during growth and development.
Duguay
S J
SJ
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637, USA.
Lai-Zhang
J
J
Steiner
D F
DF
Funkenstein
B
B
Chan
S J
SJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D014018:Tissue Distribution
D018076:DNA, Complementary; D011498:Protein Precursors; D012333:RNA, Messenger; C093199:preproinsulin-like growth factor I; C042532:preproinsulin-like growth factor II; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II