Insulin-like growth factor I gene polymorphism associated with growth traits in beluga (Huso huso) fish

The aim of the present study was to detect polymorphism in Insulin like growth factor-I (IGF-I) gene of beluga (Huso huso) fish using PCR-SSCP technique and also investigation of its association with growth traits (condition factor, body length and weight). A total of ۱۵۰ specimens of beluga were randomly selected and DNA was isolated from caudal fin using modified salting out method. Then two fragments of ۱۷۱ and ۳۶۲ bp from ۵'-UTR and ۳'-UTR regions of IGF-I gene were amplified, respectively. Genotyping of individuals by SSCP technique showed five banding patterns of A, B, C, D and E for ۵'-UTR region with the frequencies of ۲۹.۲, ۰.۷۶, ۱۶.۹۲, ۵۱.۵۳ and ۱۰% respectively in one year-old and three banding patterns of A, C and D with the frequency of ۴۵, ۱۰ and ۴۵% for two year-old fish. Also three banding patterns (A, B and C) were seen for ۳'-UTR region with the frequency of ۶۲.۳, ۲۷.۶۹ and ۱۰.۷۶% in one-year-old and ۲۰, ۶۰ and ۲۰% in two year-old fish. The A banding pattern  in ۳'-UTR and D banding pattern in ۵'-UTR sites were the most frequent pattern in the studied beluga population. The association analysis using SAS statistical software indicated no significant association between observed banding patterns and growth traits (body length, weight, and condition factor) in beluga. Considering the important role of IGF-I as a probable candidate gene affecting growth related traits, these marker sites should be studied more in larger sample sizes and also in other regions of the gene.