Meeting Abstract

3.10  Wednesday, Jan. 4  Thermal stress induces a change in age class composition but not cell death in the circulating red blood cells of rainbow trout (Oncorhynchus mykiss) LEWIS, JM*; KLEIN, G; WALSH, PJ; CURRIE, S; Georgia Southern University, Statesboro, GA; Mount Allison University, Sackville, NB; University of Ottawa, Ottawa, ON; Mount Allison University, Sackville, NB jmlewis@georgiasouthern.edu

Freshwater fish, such as the rainbow trout, are commonly exposed to temperature fluctuations in their aquatic environment. Exposure to increased temperatures places fish under respiratory stress and increases the susceptibility for protein misfolding and degradation that could eventually lead to cell death. Previous work by our group has shown genes associated with the cellular stress response, apoptosis and hematopoiesis to be up-regulated in the red blood cells (RBCs) of rainbow trout post thermal stress. These results suggest a tightly regulated interaction between cell repair and cell death is occurring post heat stress. Additionally, the triggering of hematopoiesis (specifically synthesis of RBCs) is likely an attempt to increase blood-oxygen carrying capacity in the fish. To further this work, changes in age class composition and markers of apoptosis in circulating RBCs were tracked within individual trout during exposure to and recovery from acute thermal stress. RBCs did now show any indication of apoptosis or necrosis post heat stress, however significant increases numbers of early, juvenile and dividing RBCs in were observed. These results suggest the induction of molecular chaperones provides sufficient protection against thermal stress in the RBC, subsequently preventing the initiation of the cell death cascade. Trout also appear to be shifting the composition of the circulating RBCs towards a younger cohort through release of stored cells from the spleen and increasing the maturation rate of early RBCs.