Short-term hardening effects on survival of acute and chronic cold exposure by Drosophila melanogaster larvae

Abstract

We quantified the variation and plasticity in cold tolerance among four larval stages of four laboratory strains of Drosophila melanogaster in response to both acute (<2 hours of cold exposure) and chronic (∼7 hours of cold exposure) cold exposure. We observed significant differences in basal cold tolerance between the strains and among larval stages. Early larval instars were generally more tolerant of acute cold exposures than 3 rd instar larvae. However, wandering larvae were more tolerant of chronic cold exposures than the other stages. Early stages also displayed a more pronounced rapid cold-hardening response than the later stages. Heat pre-treatment did not confer a significant increase in cold tolerance to any of the strains at any stage, pointing to different mechanisms being involved in resolving heat-and cold-elicited damage. However, when heat pre-treatment was combined with rapid cold-hardening as sequential pre-treatments, both positive (heat first) and negative (heat second) effects on cold tolerance were observed. We discuss possible mechanisms underlying coldhardening and the effects of acute and chronic cold exposures.

Mortality from desiccation contributes to a genotype-by-temperature interaction for cold survival inDrosophila melanogaster

“…Interestingly, the beneficial effects of cold acclimation treatments can differ across temperatures (Chen and Denlinger, 1992;Chen and Walker, 1994;Rajamohan and Sinclair, 2008). Although our study only measured basal cold survival, our results provide a possible explanation for the differential effects of acclimation on cold survival.…”

“…the cell membranes) are compromised across this range of cold. It is known that cold survival in D. melanogaster differs between genetic strains, for acute versus chronic cold exposure and with different acclimation treatments (Chen and Walker, 1994;Rajamohan and Sinclair, 2008). Here we investigated basal cold survival in five genotypes across six densely sampled cold temperatures, allowing us to quantify strong effects of genotype-temperature interactions on cold survival across a relatively continuous gradient of cold exposure.…”

“…The loss of ion homeostasis during cold exposure may have effects that are similar to the effect of dehydration on ion balance. Ion imbalance may affect protein folding (Record et al, 1998), and the association of heat shock protein expression with both cold and desiccation may be the result of a shared response to misfolded proteins (Benoit et al, 2010;Burton et al, 1988;Hayward et al, 2004;Kostál et al, 2009;Petersen et al, 1990;Rajamohan and Sinclair, 2008;Sinclair et al, 2007a). Both extreme dehydration and low temperature can have similar effects on membrane fluidity (Crowe et al, 1992).…”

Phenotypic plasticity of thermal tolerance contributes to the invasion potential of Mediterranean fruit flies (Ceratitis capitata)

“…However, a pre-treatment at 0 and 35 • C also significantly improved survival in C. capitata, although a full hardening response was not achieved. High temperature exposures may confer low temperature tolerance (see Chen et al, 1991;Sinclair & Chown, 2003;Rajamohan & Sinclair, 2008). However, high and low temperature could be different stressors, and it has been argued that the mechanisms for high and low temperature tolerance may be fundamentally different (Hoffmann et al, 2003; but see discussions in Chown & Nicolson, 2004;Sinclair & Roberts, 2005).…”

Divergent transcriptomic responses to repeated and single cold exposures in Drosophila melanogaster

“…There is also evidence for cross-tolerance, whereby exposure to one stress, for example heat, improves tolerance of another, such as cold (e.g. Bayley et al, 2001;Le Bourg et al, 2009;Rajamohan and Sinclair, 2008).…”