Effects of temperature and nutrition interactions on growth, protein metabolism and gene expression in fish: understanding possible impacts of climate change on aquaculture

Asian sea bass or barramundi (Lates calcarifer) performs optimally over a wide temperature range and also maintains high levels of growth performance outside of its optimum range. Limiting environmental conditions, particularly those imposed by sub-optimum temperatures test the adequacy of nutrient supply and the efficiency of growth. Consequently, Asian sea bass provides a model species with which to study how environmental factors affect growth processes. Protein metabolism was investigated in detail: protein synthesis was modeled in relation to temperature and nutritional factors such as time after feeding, dietary protein content and protein source. Daily rates of protein synthesis were related to changes in protein degradation, investigation of autophagic-lysosomal and ubiquitin-proteasome protein degradation pathways showed a significant increased gene expression of Cathepsin D but no other significant changes. Combining data from a series of experiments highlight mechanisms underlying changes in growth performance at extreme temperatures and suggested an increase in the use of dietary amino acids for energy and increased metabolism via deamination and excretion. The use of model species to study nutritional physiology and implications for understanding possible impacts of climate change will be discussed further.