A major emphasis of the fish reproduction group within the Physiology Program at the Northwest Fisheries Science Center is to improve our understanding of the environmental and endocrine control of reproduction in salmon. Our basic research aims to reveal the functions of pituitary gonadotropins in regulating early stages of gametogenesis and the endocrine mechanisms whereby metabolic status influences puberty onset in fish. Our applied work is directed toward improving effectiveness of captive breeding programs for endangered stocks of Pacific salmon by developing rearing regimes to reduce early age of puberty in males and improve fertility of adults. These studies are largely focused on determining how growth at critical phases of the life cycle influence age of maturity, fecundity, egg size, and gamete quality. Since growth is influenced by food availability, food quality, temperature and genetics, these research results have implications for understanding the impacts of hatchery practices, habitat quality, and global warming on the fitness of salmon, whether they are wild or hatchery fish. More recently, we have initiated a new line of research that examines how a variety of chemical contaminants (e.g. pharmaceuticals, flame retardants) disrupt the thyroid and reproductive systems of salmon and laboratory model species such as, zebrafish and fat head minnows.
Lema, S.C., J.T. Dickey, I.R. Schultz, and P. Swanson. "Thyroid hormone regulation of mRNAs encoding thyrotropin beta-subunit, glycoprotein alpha-subunit, and thyroid hormone receptors alpha and beta in brain, pituitary gland, liver, and gonads of an adult teleost, Pimephales promelas." J Endocrinol, 2009. 202(1): p. 43-54.
Lema, S.C., J.T. Dickey, I.R. Schultz, and P. Swanson. "Dietary exposure to 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47) alters thyroid status and thyroid hormone-regulated gene transcription in the pituitary and brain." Environ Health Perspect, 2008. 116(12): p. 1694-9.
Luckenbach, J.A., Iliev, D.B., Goetz, F.W. and Swanson, P. (2008). "Identification of differentially expressed ovarian genes across previtellogenic stages in coho salmon." Reproductive Biology and Endocrinology 6:2-16.
Luckenbach, J.A., Goetz, F.W. and Swanson, P. (2008). "Expressed sequence tags (ESTs) of follicle/interstitial cell enriched ovarian tissue from previtellogenic coho salmon." Cybium in press
Swanson, P., Campbell, B., Shearer, K., Dickey, J., Beckman, B., Larsen, D., Park, L., and Berejikian, B. (2008). "Application of reproductive technologies to captive breeding programs for conservation of imperiled stocks of Pacific salmon." Cybium in press
Lema, S.C., J.T. Dickey, and P. Swanson. "Molecular cloning and sequence analysis of multiple cDNA variants for thyroid-stimulating hormone beta subunit (TSHbeta) in the fathead minnow (Pimephales promelas)." Gen Comp Endocrinol, 2008. 155(2): p. 472-80.
Lema, S.C., I.R. Schultz, N.L. Scholz, J.P. Incardona, and P. Swanson. "Neural defects and cardiac arrhythmia in fish larvae following embryonic exposure to 2,2',4,4'-tetrabromodiphenyl ether (PBDE 47)." Aquat Toxicol, 2007. 82(4): p. 296-307.
Pierce, A.L., M. Shimizu, L. Felli, P. Swanson, and W.W. Dickhoff. "Metabolic hormones regulate insulin-like growth factor binding protein-1 mRNA levels in primary cultured salmon hepatocytes; lack of inhibition by insulin." J Endocrinol, 2006.191(2): p. 379-86.