Insulin-like growth factor IEa2 is the predominantly expressed form of IGF in common carp (Cyprinus carpio)

An insulin-like growth factor (IGF) complementary DNA (cDNA) was isolated from a liver cDNA library of adult common carp, Cyprinus carpio. The identity of this cDNA clone was confirmed by nucleotide sequence determination. Sequence comparison with other vertebrate and rainbow trout IGFs showed that this cDNA encodes a particular subtype of IGF-I, IGF-IEa2. A reverse transcription-polymerase chain reaction (RT-PCR) assay showed that this IGF-I is expressed mainly in the liver (hepatopancreas) of adult common carp. Analyses of 26 other cDNA clones isolated from the same library (using a probe carrying the conserved region of the common carp IGF-IEa2 cDNA clone) showed that these clones represent different insert sizes of the same IGF-IEa2. In conclusion, IGF-IEa2 is the predominantly expressed IGF in the liver of adult common carp.