The effect of diet on immune gene expression and parasite resistance in fish

Carotenoids are powerful antioxidants often used as dietary additives in aquaculture, and reputed to have effects on immune function, but these, and the consequences for resistance to the parasitic infections that plague farmed fish, are poorly understood. Carotenoids are also commonly used by animals in sexual displays, including the nuptial colouration of three-spined stickleback. The evolutionary significance of these signals remains unclear, but could be associated with the advertisement of immune function or resistance to oxidative stress. This project will use natural variation in fish populations and manipulations of diet, to investigate the effect of carotenoids on fluorescence-based cellular assays of oxidative stress, proinflammatory immune responses and disease resistance in three-spined stickleback.

The project will work with diverse populations of stickleback on the Scottish island of North Uist, where we have already documented large variation in diet, carotenoid availability, parasite resistance and immune function among lakes. The student will use this variation to investigate carotenoid uptake and use efficiency by fish, its genetic basis and how this relates to diet. The findings will be relevant to the study of aquaculture, to understanding the effects of nutrition on immune function and to the ecology and evolution of wild fish populations.