Submitted to: World Aquaculture Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2003
Publication Date: March 1, 2004
Citation: Peterson, B.C., Waldbieser, G.C., Bilodeau, A.L. 2004. IGF-II mRNA expression in slow and fast growing families of NWAC103 channel catfish. World Aquaculture Society Meeting. Honolulu, HI. p. 466. Technical Abstract: Differences in growth exist among genetic families of NWAC103 channel catfish. Identifying genes involved in regulating growth may prove important to selecting fish for efficient lean growth. Insulin like growth factor-I and 'II (IGF-I and IGF-II) are involved in the proliferation and differentiation of muscle cells and have been identified in many species of fish. Expression of IGF-II in relation to growth in channel catfish is not known. Research was conducted to examine IGF-II mRNA expression in slow and fast growing families of NWAC103 channel catfish. Three hundred and twenty fish (18.1 +/- 2.4 g) from eight families were grown for six weeks in 76-l tanks (10 fish/tank). The fish were supplied with 26.0 degrees Celsius well water and fed a 36% CP commercial diet once a day to apparent satiation. At the end of the six-week study, the fish were weighed and muscle and liver samples were taken for RNA extraction. Relative expression of IGF-II mRNA was determined by real time RT-PCR in fast (I8) and slow (I1) growing families of fish. Results of the growth study demonstrated that specific growth rate (SGR) and food conversion ratio (FCR) were the same in 7 (I8,G8,C6,G6,H6,F2,I5) of the 8 families (Figure 1). Family I1 was slower growing and had a poorer FCR (P < 0.01) (Figure 1). Expression of IGF-II mRNA was 5 and 46 times greater in muscle and liver of fast growing fish (I8), respectively, relative to slow growing fish (I1) muscle and liver. These results confirm growth rate and feed efficiency differences among NWAC103 catfish families. IGF-II could potentially be a candidate gene whose expression may reflect differences in muscle growth. Examination of other genes such as IGF-II receptor and IGF-I and its receptor may also contribute to our understanding of muscle growth in channel catfish.