HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Peterson, B. C. Articles by Bilodeau, L. Search for Related Content PubMed PubMed Citation Articles by Peterson, B. C. Articles by Bilodeau, L.

Effects of recombinant bovine somatotropin on growth and abundance of mRNA for IGF-I and IGF-II in channel catfish (Ictalurus punctatus)^1,2

ARS, USDA Catfish Genetics Research Unit, Thad Cochran National Warmwater Aquaculture Center, Stoneville, MS 38776

³ Correspondence to: 141 Experiment Station Rd. (phone: 662-686-3589; fax: 662-686-3567; e-mail: bpeterson{at}ars.usda.gov).

Research was conducted to examine growth rates, circulating concentrations of IGF-I, and mRNA abundance levels of IGF-I and IGF-II in channel catfish (Ictalurus punctatus) given recombinant bovine ST (rbST; Posilac, Monsanto Co., St. Louis MO). In the first study, juvenile catfish (5.5 ± 0.5 g) were randomly assigned to one of three treatments: 1) sham-injected control (one needle puncture per week); 2) rbST (30 µg•g BW^–1•wk^–1; Posilac); and 3) nonhandled control (control). At the end of the 6-wk study, the fish were weighed, measured for length, and G:F was determined. Compared with sham and control treatments, rbST-treated fish had 48% greater final BW, 14% greater total length, and 52% greater G:F (P < 0.001). In the second study, juvenile catfish (41.1 ± 1.5 g) were assigned randomly to one of two treatments: 1) sham or 2) rbST. Eight fish per treatment were sampled on d 0, 1, 2, 7, 14, and 21 for blood, muscle, and liver. Relative expression of IGF-I and IGF-II mRNA was determined by real-time PCR and plasma concentrations of IGF-I were measured using a validated fluoroimmunoassay. Circulating concentrations of IGF-I were increased (37.9 ± 5.5 vs. 22.0 ± 6.6 ng/mL; P < 0.05) in rbST-injected fish compared with sham-injected controls by d 14. Liver IGF-I and IGF-II mRNA was increased 4.3-and 14.4-fold, respectively, by d 1 in rbST-injected fish compared with controls (P < 0.05); however, abundance of liver IGF-I and IGF-II mRNA did not differ from controls on d 0, 2, 7, 14, and 21. Abundance of muscle IGF-I and IGF-II mRNA did not differ in rbST-injected fish compared with controls throughout the study. Results of the first study demonstrated that rbST improves growth performance of channel catfish. Results of the second study showed that the growth-promoting effects of rbST were not mediated by the expression of IGF-I or IGF-II mRNA in the muscle. Instead, the results suggest that rbST promotes growth by stimulating plasma IGF-I release, possibly through its direct effect on the liver or on local tissues to synthesize IGF-I. The changes in mRNA abundance and plasma concentrations of IGF-I support the role of IGF-I in growth regulation of channel catfish.

Key Words: Catfish • Insulin-Like Growth Factor-I • Insulin-Like Growth Factor-II • Somatotropin

This article has been cited by other articles:

				M. E Picha, M. J Turano, C. K Tipsmark, and R. J Borski Regulation of endocrine and paracrine sources of Igfs and Gh receptor during compensatory growth in hybrid striped bass (Morone chrysopsxMorone saxatilis) J. Endocrinol., October 1, 2008; 199(1): 81 - 94. [Abstract] [Full Text] [PDF]