Mechanisms of stress adaptation in fish: the role of changes in gene expression

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Stress is an important aspect of life for all organisms. The study of stress is especially important in aquatic species such as fish that are of societal, aesthetic or economic importance. Stress can be imposed by the external physical or biological environment, or some process that an organism undertakes (e.g., prey capture, feeding, mating, etc.). While the term stress has come to have a negative connotation by the standards of modern human life, not all stress is bad. Stress can be viewed as a positive when an organism is capable of coping with stress by activating a series of adaptations to remove itself from or mitigate the stress (so-called 'eustress'). It is only when these coping mechanisms are exceeded that stress becomes a negative (distress). This proposal describes comparative experiments aimed at a better mechanistic understanding of stress in several species of fish (toadfish and its relatives, dogfish sharks, and rainbow trout). Until recently, biologists have had to study reactions of fish to stress by examining one gene or gene family at a time. However, through extensive DNA sequencing and microarray (chip) experiments, we are now able to study the responses of  literally thousands of genes in a single organism at a time. Therefore, this research will extend our past approach of examining single genes (primarily those of nitrogen waste production and excretion) with the microarray-based approaches to study multiple gene responses to stress. The stresses/processes we will examine are crowding stress, air-exposure, ammonia exposure, ingestion of large sporadic meals, hypoxia and exercise. Through studies of large numbers of genes, multiple species and multiple stressors, we hope to gain a broader appreciation of the genes that are common to all stresses, the genes that are specific to only some stresses, and more generally how stress acts to change patterns of gene expression in fish.