Seasonal production of cryoprotectants and body water content has been well documented in overwintering insects. However, cryoprotectant production is usually reported as a total accumulation, rather than the distribution between intra- and extracellular compartments, and body water is assumed to be comprised of mostly bulk water. To determine the distribution of cryoprotectants in overwintering Eurosta solidaginis larvae, both whole body and hemolymph concentrations of glycerol and sorbitol were measured in larvae collected in October, December, and January. Hemolymph glycerol was significantly higher in larvae collected in December and compared to those October (p≤0.05; 339.6±12.78mM and 236.8±9.3mM respectively). The majority of total glycerol content was located in the hemolymph across all collection groups with an average of 86%. Sorbitol content was also significantly higher in larvae collected in December compared to those collected in October (p≤0.05; 25.1±3.2mM and 37.3±4.9mM respectively). Hemolymph sorbitol content was undetectable in larvae collected in October and in larvae held at room temperature for four days. In summary, glycerol content is localized in extracellular compartments while sorbitol tends to be localized in intracellular compartments. To determine seasonal bound water, the amount of unfrozen body water was measured in larvae collected in October, December, and January using a differential scanning calorimeter. Total glycogen content was measured for each collection group was measured in order to determine if glycogen was a major source of bound water content in E. solidaginis larvae. Interestingly, although glycogen was significantly larger in larvae collected in October compared to all other collection groups (p≤0.05; 122.6±20.9 mg*g dry mass-1 and 30.6±7.8 mg*g dry mass-1 respectively), bound water was not significantly altered. A subset of larvae collected in January was held at room temperature in order to influence sorbitol concentrations to determine if sorbitol content affected bound water. Although sorbitol concentrations were significantly lower (p≤0.05) in the larvae held at room temperature (19.6±2.1mM) compared to those collected in December and January (31.2±3.2mM), bound water remained constant among all groups with an average of 24.9±0.979% of total body water. In summary, bound water does not seem to change seasonally and is unaffected by alterations in glycogen or sorbitol concentrations.
|Commitee:||Duvernell, David, Leibl, Faith|
|School:||Southern Illinois University at Edwardsville|
|School Location:||United States -- Illinois|
|Source:||MAI 52/05M(E), Masters Abstracts International|
|Keywords:||Bound water, Cryoprotectants, Eurosta solidaginis, Overwintering|
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