Date of Completion

2018

Document Type

Honors College Thesis

Department

Biology

Type of Thesis

Honors College

First Advisor

Sara Helms Cahan

Keywords

ants, cold tolerance, sugar, acclimation, rapid cold hardening, temperature

Abstract

Ants living in thermally variable environments need to be able to tolerate both high and low temperature extremes. One way that insects handle cold is through the accumulation of cryoprotectants, such as sugars, that increase cold tolerance by lowering the freezing point of liquids in the hemolymph. The disaccharide sugar molecule trehalose is an important cryoprotectant in many insect species, but its role has not yet been studied in ants. I investigated whether the northern forest ant Aphaenogaster picea resists cold by producing trehalose from sugars in their diet. To understand whether dietary trehalose or its monosaccharide, glucose, increases cold tolerance, recovery from cold shocks at 0 °C and -5 °C was compared for ants maintained on trehalose, glucose or no-sugar diets. To determine whether workers produce trehalose in response to cold exposure, whole-organism metabolite concentrations following rapid cold hardening (RCH) or gradual acclimation were compared to room-temperature (RT) controls. While dietary sugar improved baseline cold tolerance, trehalose was not present at detectable levels regardless of condition, suggesting that it is not used as a cryoprotectant in A. picea. Other sugars present in the hemolymph may help increase cold tolerance in a cryoprotectant capacity, or they could be used as an energy source. Metabolites associated with scavenging of reactive oxygen species increased under both exposures, and during acclimation the amino acid proline increased, suggesting that it may act as a cryoprotectant to stabilize cell membranes under longer term exposure. Therefore, while trehalose is not involved in increasing cold tolerance, A. picea may rely on other molecules to handle the cold.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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