Title: Chronic exogenous kisspeptin administration accelerates gonadal development in basses of the genus Morone Authors
Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 26, 2012
Publication Date: May 4, 2012
Citation: Beck, B.H., Fuller, S.A., Peatman, E., McEntire, M.E., Darwish, A.M., Freeman, D.W. 2012. Chronic exogenous kisspeptin administration accelerates gonadal development in basses of the genus Morone. Comparative Biochemistry and Physiology. 162A(3):265-273. Interpretive Summary: The KISS1 and KISS2 genes produce proteins termed kisspeptins that naturally control when an animal enters puberty. In aquaculture, one of the major obstacles to the commercial production of different species is the long period of time required for reproductive development of broodfish; fish that are used to generate supplies of offspring that will be grown as foodfish. In addition when fish are in captivity many species produce low numbers of viable eggs and sperm. To confront this problem, we studied the effects of administering kisspeptins (by injections in the muscle) to sexually immature fish to determine if the onset of puberty could be accelerated. We also examined whether treating adult fish with kisspeptins could increase the size and quality of their reproductive organs. We found that kisspeptin treatment of young male white bass could speed up puberty. In adult female fish, kisspeptin treated fish had larger ovaries with more mature eggs. Together these findings highlight the potential usefulness of kisspeptin treatments and we expect that these results could be used by producers to improve their breeding programs and ultimately improve profit margins.
Technical Abstract: The present study assesses the effects of chronic administration of peptides to fish, termed kisspeptins, which are the products of the KISS1 and KISS2 genes, and have been shown to control the development of puberty in animals. Using ecologically and commercially important species (white bass, Morone chrysops, striped bass, M. saxatilis, and their hybrid) as models, we determined that repeated bi-weekly injections (over 8 weeks) differentially accelerate puberty, as evidenced by increases in the prevalence of spermatozoa in the testes of juvenile fish. Moreover, in sexually mature fish, kisspeptin treatment improved markers of fecundity, including gonad weight and gonadosomatic index in white and striped bass. Additionally, mature white bass treated with kisspeptins showed an increase in the percentage of mature oocytes present during histological examination. These gonadal changes occurred in the absence of any photothermal manipulation or industry-standard hormone injections. To date, this is the first description of kisspeptin-mediated pubertal initiation in fish, and the first evidence that kisspeptins could potentially improve fecundity. Although it remains to be determined how kisspeptins may best be utilized in industry practice, our findings are driving future studies to characterize the molecular underpinnings of the KISS system in various foodfish species.