Title: Administration of kisspeptins accelerates gonadal development and alters gene expression in Moronids Authors
Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: September 25, 2012
Publication Date: February 20, 2013
Citation: Fuller, S.A., Beck, B.H. 2013. Administration of kisspeptins accelerates gonadal development and alters gene expression in Moronids [abstract]. Book of Abstracts Aquaculture America 2013: Strike a Chord for Sustainable Aquaculture, February 21-25, 2013, Nashville, Tennessee. p.374. 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. 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. In addition, when fish are in captivity many species produce low numbers of viable eggs and sperm. We studied the effects of administering kisspeptins (by twice-weekly 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. To further characterize the effects of kisspeptin injection, gonadal tissue samples were collected from representatives of each treatment group to characterize differential gene expression patterns from genes known to play a role in reproduction. Using white bass, Morone chrysops, and striped bass, M. saxatilis, 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. In sexually mature fish, kisspeptin treatment significantly improved markers of fecundity, including gonad weight and gonadosomatic index in white and striped bass. 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. Additionally, kisspeptin injection led to a significant upregulation of several reproductive genes (gdf9, bmp15, kiss1r, srebp1) and a significant decrease in others (kiss1 or kiss2, depending on which peptide was injected) in kisspeptin-treated male and female bass versus controls. Kisspeptins also had a more pronounced effect (larger fold-change) on gene expression in male-treated compared to female-treated bass relative to controls. 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.