Meeting Abstract

1.5  Thursday, Jan. 3  Development of mRNA biomarkers for the study of intracellular stress in elasmobranchs NUNEZ, B.S*; DAVIS, J.; SIMPSON, M.; OLSON, M.; The University of Texas at Austin Marine Science Institute; The University of Texas at Austin Marine Science Institute; Virginia Polytechnic Institute and State University; University of San Diego nunez@utmsi.utexas.edu

Disturbances in the extracellular milieu perturb intracellular homeostasis and must therefore be countered to stabilize the intracellular environment. The intracellular response to such stressors is typically defined by the nature of extracellular changes and by the systemic release of stress hormones. However, some molecules seem to be a ubiquitous part of the intracellular stress response, regardless of the stressor. For example, in many vertebrates the mRNAs encoding heat shock protein 70 (HSP70; a protein chaperone) and serum glucocorticoid kinase-1 (SGK-1; a cell survival protein) are rapidly induced by a number of stimuli. We isolated mRNA sequences encoding HSP70 and SGK-1 from the Atlantic stingray (Dasyatis sabina) and the Atlantic sharpnose shark (Rhizoprionodon terraenovae). These sequences are highly conserved between vertebrates, with greater than 80% identity between elasmobranch and mammalian amino acid sequences. Both mRNAs were detected in all tissues examined, including red blood cells (RBCs). Fish RBCs are nucleated and therefore have the metabolic capacity with which to support gene transcription and protein synthesis; they are also frequently among the first cells to be exposed to environmental insults. RBCs may therefore represent an excellent model for the study of the intracellular stress response in elasmobranchs. Both HSP70 and SGK-1 mRNAs are present in Atlantic stingray and Atlantic sharpnose shark RBCs. Preliminary evidence indicates that stressors (e.g. capture, changes in salinity) can alter the concentration of these mRNAs, suggesting they may serve as good biomarkers of intracellular stress in elasmobranchs.