*To whom correspondence and reprint requests should be addressed. Cloning and Characterization of Insulin-like Growth Factor I cDNA

and Jen-Leih Wu (1998) Cloning and characterization of insulin-like growth factor I cDNA from black seabream (Acanthopagrus schlegeli). Zoological Studies 37(3): 213-221. A cDNA library was constructed in Uni-ZAP XR using mRNA from the liver of black seabream, Acanthopagrus schlegeli. In this study, we designed a pair of primers from the C and E domains of trout IGF-I cDNA, and synthesized an internal probe of IGF-I from the liver of black seabream by reverse transcription/polymerase chain reaction (RT/PCR). Using the internal probe to screen the cDNA library, we obtained 16 positive clones. Subsequent restriction enzyme map analysis suggested that about 6 forms ranging in size from 1.8 kilo-base pair (kb) to 2.3 kb of IGF-I were present. We took 2 longer cDNA clones to read the full sequence. Sequences of 2 clones of IGF-I cDNAs were found to be 2238 base pairs (bp) and 2299 bp in length. Except for a sequence of 61 nucleotides missing in the 5'-untranslated region (5'-UTR) and 6 nucleotides being different in the 3'-untranslated region (3'-UTR), the other nucleotides of these 2 clones are identical. This showed that the black seabream IGF-I gene contains polymorphism or gene duplication. Both cDNAs containing an open reading frame (ORF) encode 185 amino acids, including a 44-amino acids leader peptide, the 67-amino acids mature peptide in the B, C, A, and