Partial Sequence Characterization of Insulin-like Growth Factor-I (IGF-I) Gene in Mekong Giant Catfish (Pangasianodon gigas) and Striped Catfish (Pangasianodon hypophthalmus)

Abstract

Insulin-like growth factor-I (IGF-I) plays an important role in development and growth of multiple species including fishes. IGF-I may also contribute to high growth traits of an endangered species and the largest fresh-water fish, the Mekong giant catfish (Pangasianodon gigas) as well as an economically important species, striped catfish (Pangasianodon hypophthalmus). Nevertheless, nucleotide sequences of IGF-I in these two species has not been available. Thus, the goals of this research are to study sequence isolation and comparative sequencing of IGF-I of the other species. Degenerate primers were designed from a highly conserved region of a closely related species, channel catfish (Ictalurus punctatus). A fragment of 146 bp was amplified, cloned and sequenced from P. gigas and P. hypophthalmus DNA samples. A sequence comparison showed 99.3% of sequence similarity, and comparative sequencing identified the single nucleotide polymorphisms (SNPs) at g.60C > T position between P. gigas and P. hypophthalmus. The Neighbour Joining clustering analyses grouping the catfish (P. gigas, P. hypophthalmus and I. punctatus) with 24.4% of sequence similarity from consensus sequence of other species. This is the first report on nucleotide sequence of the P. gigas and P. hypophthalmus IGF-I gene. The results provide essential information for sequence relationship study and further understanding functional roles of IGF-I in Mekong giant catfish and striped catfish.