In ectotherms, high temperatures impose physical limits, impeding activity. Exposure to high heat levels causes various deleterious and lethal effects, including protein misfolding and denaturation. Thermophilic ectotherms have thus evolved various ways to increase macromolecular stability and cope with elevated body temperatures; these include the high constitutive expression of molecular chaperones. In this work, we investigated the effect of moderate to severe heat shock (37°C–45°C) on survival, heat hardening, protein damage, and the expression of five heat-tolerance related genes (hsc70-4 h1, hsc70-4 h2, hsp83, hsc70-5, and hsf1) in two rather closely related Cataglyphis ants that occur in distinct habitats. Our results show that the highly thermophilic Sahara ant Cataglyphis bombycina constitutively expresses HSC70 at higher levels, but has lower induced expression of heat-tolerance related genes in response to heat shock, as compared to the more mesophilic C. mauritanica found in the Atlas Mountains. As a result, C. bombycina demonstrates increased protein stability when exposed to acute heat stress but is less prone to acquiring induced thermotolerance via heat hardening. These results provide further insight into the evolutionary plasticity of the hsps gene expression system and subsequent physiological adaptations in thermophilous desert insects to adapt to harsh environmental conditions.
- Received November 29, 2016.
- Accepted February 17, 2017.
- © 2017. Published by The Company of Biologists Ltd