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Pat Walsh - Research

My laboratory has examined comparative/evolutionary and ecological aspects of the physiology, biochemistry and molecular biology of aquatic animals, especially marine fish, mollusks, crustaceans and cnidarians; aquatic toxicology/physiology and biochemistry of xenobiotic metabolism; biochemical and molecular phylogeny and genetics of populations. Currently, we have two ongoing projects areas:

Major Research Interests

1. Responses to feeding by dogfish shark rectal gland
Following feeding, dogfish sharks and other elasmobranch fishes activate the rectal gland to secrete concentrated solutions of NaCl to rid their bodies of the salt load from feeding. Along with this activation is a tremendous activation of metabolism to support this secretion. We have noted increases in the activities of several enzymes of metabolism already. Proteomic and functional genomic studies are underway to determine more broadly what changes in gene expression occur following feeding. In vivo studies are conducted at Bamfield Marine Sciences Centre in British Columbia.

2. Regulation of expression and evolution of glutamine synthetase, urea transporters, and Rhesus proteins (ammonia transporters) in gulf toadfish
Toadfish use urea excretion as part of an elaborate system to confuse predators, specficially to mask the scent of their own excreted ammonia. The genes controlling the synthesis of urea (glutamine synthetase or GS) and excretion of urea (urea transporter or UT) have been shown to be induced by rises in plasma cortisol brought on by stress in the toadfish system. This project examines the role of cortisol response elements in the promoter region of the GS and UT genes in controlling their expression. Also of interest is the tissue-specificity of gene expression. Notably for GS there are two genes identified, with one specific to the gill. For UT and Rh, we wish to determine which cells within the gill express these genes. In addition to molecular methods, immunocytochemistry and in situ hybridization approaches are of use.