Heat acclimation and its correlation pattern with expression level of some candidate genes in recombinant inbred lines of Drosophila melanogaster (Diptera: Drosophilidae)

ALMIRON M; GOMEZ, FH.; SAMBUCETTI P.; NORRY F M

La Plata

Congreso; XI Congreso Argentino y XII Congreso Latinoamericano de Entomología; 2022

Universidad Nacional de la Plata

Heat acclimation is the increase in heat tolerance induced by long-term cyclicexposures to elevated temperature. In ectotherms, heat acclimation might mitigateglobal warm effects, and the ability in acclimating might differ betweenpopulations from different latitude. Here we used recombinant inbred lines(RIL) of Drosophila melanogaster which were previously obtained from backcrossesbetween populations from Denmark and Australia that highly differ in latitude. Oneset of cultures were reared for each one of 65 RIL under constant 25°C (control)whereas another set was exposed to a cycle of thermal ramping from 26°C (8:00h) to 36°C (16:00 h), from egg to adult of 3-4 days of age, when flies weremeasured for time (in sec) of heat knockdown at 37°C (KD). KD was measured inboth control and heat-treated flies, and aclimation was estimated for each RILas the mean difference between KD in heat teatred and control flies. Seven RILshowing high variability for acclimation were selected for analysis ofexpression levels, previously estimated by RT-qPCR for each RIL, of sevencandidate genes: Trap1, Catsup, Ddc, hsp60,hsp70-3, CG10383, Cyp6a13),  … in bothcontrol and heat-hardened flies. The results revealed a high degree of geneticvariation in acclimation across RIL, as some RIL did not acclimated whereasother RIL improved heat tolerance for more that 30% by acclimation. Acclimationwas strongly negatively correlated to expression level of Trap1 (Spearman rank correlation: rs= -0.91***), Ddc(rs= -0.78***) and Catsup (rs= -0.76***) in control flies as well as inheat-hardened flies (Trap1, rs=-0.57*; Ddc, rs = -0.78***;Catsup, rs= -0.76***), and more weakly so with hsp60 (rs= -0.56*. *P<0.05; ***P<0.005). Previous studies in the same set of RIL showed that KDwithout acclimation is positively correlated to expression level of Trap1 and negatively correlated to hsc70-3. Taken together, the present andprevious results on the same set of RIL suggest that the ability to acclimatedecrease with elevated levels of Trap1, Ddc, Catsup and Hsp60 proteins, asopposed to basal (non-induced) thermotolerance.