We are interested in how teleost and elasmobranch fishes adapt to different salinities. These studies involve examination of membrane lipid and transporters as well as solute changes. Changes in metabolic pathways, particularly those involving nitrogen compounds are being investigated using 15N labelled compounds.
The membrane and metabolic alterations during metabolic arrest in terrestrial snails and African lungfish are also of interest since these organisms undergo a reduction in metabolism at a constant temperature (estivation). This allows us to more easily define the changes associated with metabolic arrest compared to animal hibernation models where temperature is also a variable.
Comparative and Evolutionary Aspects of Metabolism
Some metabolic pathways seem to map more closely to environmental conditions that to phylogenetic relations. In particular, ketone body metabolism of molluscs is of interest. We have shown that while terrestrial and freshwater molluscs have a well developed ketone body metabolism, marine molluscs do not express the terminal enzyme in the pathway (β-hydroxybutyrate dehydrogenase).
The metabolism of elasmobranch fishes differs substantially from that of virtually all other vertebrates due to the need to synthesize substantial amounts of urea for osmotic support. This need changes when elasmobranches enter freshwater. We have examined the metabolic changes associated with salinity challenge in elasmobranches. Current research is focused on some of the factors associated with disease resistance in elasmobranches.