Transmission and phenotypic effects of an antifreeze GH gene construct in coho salmon (Oncorhynchus kisutch)

Transmission of the opAFPGHc gene construct from parental transgenic coho salmon to F-1 progeny has been observed. Just prior to first feeding, these offspring were found to fall into two distinct phenotypic classes on the basis of morphology and external colouration, One group possessed the normal brown colouration typical of coho salmon alevins, whereas the other had a distinct green colouration and showed signs of cranial deformities and opercular overgrowth. Polymerase chain reaction analysis revealed that green phenotype was correlated with the presence of the opAFPGHc gene construct, and thus colouration could be used to identify transgenic progeny, On this basis, frequencies of transgene transmission to F-1 progeny from four individuals ranged from 2.2 to 18.9%, while a fifth male produced no transgenic progeny. Prior to first feeding, the transgenic progeny were found to be 21.2% heavier and 11.9% longer than their non-transgenic siblings, suggesting that the expression of GH in early development can influence the rate or efficiency of conversion of yolk energy reserves. After 1 year of development of F-1 progeny, the atypical phenotype associated with overgrowth of cartilage in the cranial and opercular regions became progressively more severe and resulted in reduced viability.