Meeting Abstract
P2.165 Sunday, Jan. 5 15:30 Physiological, Behavioral, and Cellular Responses to Heat Stress in Lumbriculus variegatus RISALITI, RL*; SURMACZ, CA; HRANITZ, JM; Bloomsburg University; Bloomsburg University; Bloomsburg University csurmacz@bloomu.edu
Lumbriculus variegatus, the blackworm, is a useful bioindicator for assessing the health of aquatic ecosystems because it is sensitive to sublethal doses of toxins and displays a number of biological responses that can be easily measured, such as tactile response, pulse and motility. In this study, our goals were to examine the relationship between these behavioral and physiological measures of stress in blackworms and the cellular stress marker Heat Shock Protein70 (HSP70), and to determine the temperature at which these specific responses reach their peak. Individual worms were exposed for three hours to temperatures ranging from 22 to 33oC. Motility and tactile responses were measured before and after heat stress and scored as normal, slight or none. Pulse rate was determined by counting pulsations of the dorsal artery before and after heat stress. HSP70 levels were measured in worm homogenates using an ELISA. Significant changes occurred in motility, pulse, tactile response and HSP70 levels as temperature increased (P<0.001); all variables tested displayed hormetic stress responses. Pulse rate was most sensitive to increased temperature; peak pulse rates were observed at 29oC and differed significantly from worms incubated at 27oC and 33oC (p<0.001). At 31oC, motility was absent and the HSP70 level was maximal. A complete loss of tactile response was observed in worms incubated at 33oC. Our results integrate organismal function across physiological, behavioral and cellular levels of organization and improve our understanding of the blackworm’s performance under sublethal stress. Integrating the relationships between physiological, behavioral and cellular stress responses in blackworms will be useful as a model invertebrate for sublethal population effects of pollutants in lentic ecosystems.
