Meeting Abstract

1.4  Monday, Jan. 4  Effects of Acclimation Temperature and Photoperiod on Antifreeze Protein Synthesis in the Hemolymph of Beetle Larvae (Dendroides canadensis) OWUSU-ANTWI, Y.; BENNETT, V.A.**; Clarion University of Pennsylvania; Clarion University of Pennsylvania vbennett@clarion.edu

Overwintering larvae of the fire-colored beetle, Dendroides canadensis are known to produce antifreeze proteins as a means of preventing their intracellular fluids from freezing. To investigate the cues regulating production of antifreeze proteins, summer collected D. canadensis larvae were exposed to 25°C, 5°C or a stepwise decrease in temperature (5 to 0°C or 0 to -4.5°C) under summer or winter photoperiods. Freezing and melting points of individual hemolymph samples were measured to screen for thermal hysteresis activity (THA), an indicator of the presence of antifreeze proteins. All summer insects exposed to 0 to -4.5°C died, suggesting that this sudden exposure to cold temperatures did not allow sufficient time for antifreeze protein production. Larvae exposed to 3 weeks of cold temperature (5°C; 5 to 0°C) were found to have significant increases in hemolymph thermal hysteresis when compared to larvae kept at room temperature (25°C). Levels of thermal hysteresis observed in insects exposed to 0°C were equivalent to that observed in winter-collected insects. In addition, thermal hysteresis activity was slightly higher in insects exposed to winter photoperiods at any given temperature. We concluded that temperature is a primary factor in the regulation of antifreeze proteins in D. canadensis with photoperiod playing a secondary role.