Submitted to: Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/4/2006
Publication Date: 2/1/2007
Citation: Barrero, M., Small, B.C., D'Abramo, L., Hanson, L., Kelly, A. 2007. Comparison of Estradiol, Testosterone, Vitellogenin and Cathepsin Profiles Among Two-year-old Channel Catfish (Ictalurus punctatus) Females from Four Selectively Bred Strains. Aquaculture 264:390-397. Interpretive Summary: A variety of breeding programs to improve channel catfish traits for commercial aquaculture have existed over the years, but few comparisons have been made between selectively bred strains for physiological or biochemical reproductive parameters possibly relating to spawning. The present study is the first to make such comparisons between four commercially reared strains, three of which were selectively bred in a commercial setting. Further, this is the first report of cathepsin activities and their relationships to other reproductive parameters in channel catfish, and these data represent the foundation for future investigations into the roles of cathepsins in oocyte maturation and embryo development. Although no differences were observed among the strains for any of the traits measured in the 2-yr-old females used in this study, valuable data for young-adult channel catfish has been collected that may prove useful in future research to assess what controls spawning success in channel catfish.
Technical Abstract: Potential variation in reproductive performance as young broodfish among four selectively bred strains of channel catfish was evaluated by comparing profiles of plasma estradiol, testosterone, and vitellogenin, and activities of cathepsin D, L, and B in follicle-enclosed oocytes during vitellogenesis in 2-yr-old females. No differences among the four strains were detected for any of the parameters measured. Plasma steroid concentrations demonstrated temporal differences, with testosterone levels peaking in January and estradiol levels peaking in April. Monthly changes in circulating vitellogenin concentrations coincided with oocyte growth. Average oocyte size in May, the typical time of spawning, was smaller (1624 'm) than that considered normal for mature oocytes (approx. 3000 'm) in this species. Furthermore, only 9% of the females in this study spawned, and no significant correlations could be determined between the reproductive indices and spawning success. Activities of cathepsin D, L, and B were also similar between the four strains of catfish. Cathepsin L activity was highest in March, and cathepsin D activity was highest in March and May. Cathepsin B activity was generally lower than the activities of either cathepsin L or D, with the highest levels occurring in November, December, and March. This is the first report of cathepsin activities and their relationships to other reproductive parameters in channel catfish.