B.Sc. University of British Columbia
Ph.D. Simon Fraser University
Room B8234, (778) 782-3538
mckeown@sfu.ca
Current Research Program
The research in my laboratory deals mainly with the physiology of growth hormone (GH) in salmon as it relates to migration. Studies are being carried out on external and internal environmental parameters that influence the synthesis and release of this hormone. Investigations are also in progress to elucidate the mechanisms of action for the hypothalamic releasing and inhibiting factors that control pituitary hormones. The role of GH in salmonids is not well understood and many studies are designed to uncover actions during different life cycle stages (e.g. smoltification, rapid growth, reproduction) or under differing physiological conditions (e.g. exercise, temperature, photoperiod, salinity, starvation, nutritional changes).
Prolactin studies deal mainly with how salmon can adapt to freshwater during migration. PRL appears to regulate sodium and calcium via gill, kidney, bladder, skin and intestinal tissues. PRL is controlled by hypothalamic dopamine which appears to act via a cyclic nucleotide as a second messenger. PRL is influenced by salinity, temperature, photoperiod and time of day.
Growth hormone is involved with growth (proteins, bone) and mobilization of energy reserves (carbohydrates and lipids) in salmon. It is thus an important hormone for migrating salmon during periods of exercise, salinity changes, starvation and temperature acclimatization. Salmon GH is controlled by a hypothalamic GH-releasing factor and a GH-inhibitory factor (somatostatin). Thyroid hormones appear to stimulate salmon GH mRNA. We know that GH release is controlled by various environmental parameters as well as dietary supplements which can thus greatly affect the aquaculture industry.
These studies employ biochemical procedures (column chromatography, HPLC, electrophoresis, spectrophotometry), immunological methods (radioimmunoassays, immunocytochemistry, western immunoblots), molecular techniques, bioassays, histology, and microscopy.
Selected Publications
Panno, J.P. and B.A. McKeown. 1997. Expression and regulation of the myc proto-oncogene in the pituitary gland of rainbow trout. Mol. Cell. Endocrinol. 134: 81-90.
Sweeting, R.M., G.P. Alexander, J.G. Eales and B.A. McKeown. 1994. Hepatic and branchial deiodinase activity associated with the parr-smolt transformation of coho salmon, Oncorhynchus kisutch. Gen. Comp. Endocrinol. 94: 171-181.
Alexander, G.P., R.M. Sweeting and B.A. McKeown. 1994. The shift in visual pigment dominance in the retinae of juvenile coho salmon, Oncorhynchus kisutch: an indicator of smolt status. J. Exp. Biol. 195: 185-197.
McKeown, B.A. 1984. Fish Migration. Croom Helm Publishers, London. 300 pages.
Various environmental factors (external and internal) that influence the hypothalamic control of salmon pituitary hormones and effects on physiological changes for migration.
This page last updated February 1998.