Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: September 1, 2007
Publication Date: February 9, 2008
Citation: Peterson, B.C. 2008. Nutritional Restriction and Levels of Muscle IGF-II MRNA in Channel Catfish. Aquaculture America Conference. P: 293 Technical Abstract: The growth hormone-insulin like growth factor (GH-IGF) axis plays an important role in the endocrine control of fish growth. We have previously reported differential expression of insulin like growth factor-II (IGF-II) in faster growing channel catfish families, but IGF-II’s role during nutritional restriction is not known. Research was conducted to examine changes in levels of muscle IGF-II mRNA in fed (commercial diet fed daily for 45 days) and restricted (not fed for 30 days followed by feeding a commercial diet for 15 days) channel catfish. The initial weight of all fish was 73.4 +/- 2.2 g and the fish were weighed and sampled on days 30 and 45. Dorsal muscle samples were excised from 15 fish per treatment (3 fish/tank), RNA was isolated, and relative abundance of muscle IGF-II mRNA was determined by real time PCR. By day 30, fed and restricted fish weighed 105.5 +/- 2.2 g and 65.2 +/- 3.8 g, respectively. Levels of muscle IGF-II mRNA were decreased approximately 2 fold in restricted fish compared to fed fish (P = 0.02). After 15 days of refeeding, the restricted group weighed 83.4 +/- 4.1 g while the fed group weighed 133.5 +/- 7.9 g and levels of muscle IGF-II mRNA were similar between the two treatments. Results of this study demonstrate that nutritional state regulates expression of muscle IGF-II mRNA in channel catfish. The mechanisms through which nutrition regulates IGF-II is not known but may include other modulators of the growth axis such as IGF-I, IGF-I receptor, insulin like growth factor binding proteins, and GH receptor. Further tissue specific expression studies involving these modulators will be required to fully elucidate the mechanisms through which nutritional state regulates growth of channel catfish.