Meeting Abstract
P3.202 Sunday, Jan. 6 Cryoprotectant production has little effect on bound water content in the goldenrod gall fly, Eurosta solidaginis GRIFFIS, N.L.*; WILLIAMS, J.B.; Southern Illinois Univ.; Southern Illinois Univ. jasowil@siue.edu
Most freeze tolerant insects enhance survival to low temperature by producing high concentrations of cryoprotectants. These solutes enhance survival by reducing cellular osmotic dehydration during freezing. However, recent data suggest that cryoprotectants may also enhance freeze tolerance by increasing intracellular bound water content. Properties of bound water differ from bulk water in that its close association with subcellular structures prevents it from freezing at biologically relevant temperatures. To determine if cryoprotectant production is correlated with bound water content and increased freeze tolerance, we measured seasonal changes in all three parameters in Eurosta solidaginis, the goldenrod gall fly. As expected, whole body glycerol content seasonally increased as concentrations nearly doubled from larvae collected in October (228±30mM) to those measured in December (437±38mM). Similarly, freeze tolerance dramatically increased as only 25% of October collected larvae responded to tactile stimulation 48h after being removed from a diurnal exposure to -30°C while 95% of larvae responded after a similar stress in December. In contrast, bound water content did not change regardless of collection date (averaging 23.7±1.6%) and appeared unrelated to cryoprotectant levels. In a separate experiment, a January collected set of animals subjected to room temperature for four days prior to analysis. Interestingly, the experimental group had a trend of increased bound water content (28.6±2.0%) compared to all other groups that were analyzed immediately after collection. This may have been due to temperature induced conversion of sorbitol into glycogen, however glycogen content was the same or lower in these animals (0.309±0.08mg/mg dry mass) compared to groups analyzed immediately after collection (0.60 ± 0.12mg/mg dry mass).
