Rapid decline of cold tolerance at young age is associated with expression of stress genes in Drosophila melanogaster

Abstract

SUMMARYMany endogenous factors influence thermal tolerance of insects. Among these, age contributes an important source of variation. Heat tolerance is typically high in newly eclosed insects, before declining dramatically. It is not known whether this phenomenon relates to cold tolerance also. In addition, the underlying mechanisms of this variation are unresolved. In this study, we tested whether cold tolerance declines in Drosophila melanogaster females aged from 0 to 5days. We also assessed whether expression (basal and induced) of eight stress genes (hsp22, hsp23, hsp40, hsp68, hsp70Aa, hsp83, Starvin and Frost) varied post-eclosion in correspondence with changes found in cold tolerance. We report that cold tolerance was very high at eclosion and then it rapidly declined in young flies. hsp23 and hsp68 showed a dramatic age-related variation of basal expression that was associated with cold tolerance proxies. Significant age-related plasticity of cold-induced expression was also found for hsp22, hsp23, hsp68, hsp70Aa, Frost and Starvin. Induced expression of hsp22 and hsp70Aa was high in newly enclosed phenotypes before declining dramatically, whilst opposite age-related patterns were found for hsp23, hsp68, Starvin and Frost. This study shows a marked within-stage variation in cold tolerance. The involvement of the stress genes in setting basal thermal tolerance is discussed.Supplementary material available online at http://jeb.biologists.org/lookup/suppl

Plasticity of upper thermal limits to acute and chronic temperature variation in Manduca sexta larvae

“…Tolerance may also vary with age and development stage. For example, cold tolerance of adult female D. melanogaster declines rapidly with age, presumably as a result of senescence (Colinet et al, 2013). In our study, we standardized our measurements for individuals in the same developmental stage (2nd day of the 5th instar); because developmental temperatures alter rates of larval development, these individuals necessarily vary in chronological age.…”

Drosophila Small Heat Shock Proteins: An Update on Their Features and Functions

“…Eliminating the expression of Hsp22 and Hsp23 affects the recovery from chill coma suggesting that these two proteins contribute to the adaptive response to fl uctuating thermal conditions (Colinet et al 2010a ). Since their level of cold-induction is stage-specifi c it has been proposed that they act through different mechanisms, which are still not elucidated (Colinet et al 2013 ). Consistent with a protective role of sHsps, hsp22 , hsp23 and hsp26 have been shown to contribute to cold hardening (Colinet et al 2013 ;Qin et al 2005 ).…”

“…Since their level of cold-induction is stage-specifi c it has been proposed that they act through different mechanisms, which are still not elucidated (Colinet et al 2013 ). Consistent with a protective role of sHsps, hsp22 , hsp23 and hsp26 have been shown to contribute to cold hardening (Colinet et al 2013 ;Qin et al 2005 ).…”

Response of heat shock protein genes of the oriental fruit moth under diapause and thermal stress reveals multiple patterns dependent on the nature of stress exposure

“…The most well-characterized molecular responses to thermal extremes in insects remains those involving heat shock proteins (Hsps), which are considered to play crucial roles in environmental stress tolerance and in thermal adaptation (Bedulina et al 2013;Colinet et al 2013) and often represent sensitive indicators for phenotypic adjustments (Colinet et al 2010). Proteins like Hsp70 can respond to a range of adverse conditions and also interact with a variety of other proteins in producing phenotypic effects under stress (Bettencourt et al 2008;Choi et al 2014;Colinet et al 2010).…”