Heat stress response in the cave nectar bat Eonycteris spelaea differs from that of Mus musculus

Bats as the only flying mammals incur a high metabolic cost during extended powered flight, which results in febrile-like temperatures without injury. Herein, we investigate the in vivo heat shock response (HSR) in the cave nectar bat Eonycteris spelaea. We demonstrate that E. spelaea exhibits enhanced physiological heat resistance, marked by reduced lethality, tissue damage and serum corticosterone levels in comparison to mice upon heat challenge. Additionally, E. spelaea did not exhibit an acute transcriptional response observed heat stress in mice. Instead, bats displayed a delayed and non-canonical HSR that did not involve the activation of classical heat shock related genes and pathways. This altered response in E. spelaea is attributed to the elevated basal expression of heat shock proteins, which we demonstrate to be a common characteristic exhibited by bats from diverse sub-orders, families and diets. Taken together, we demonstrate a distinct HSR in E. spelaea relative to the conventional model organism, mouse, which may provide insights to understand novel regulatory targets and effector proteins that underlie the mammalian heat shock response. To characterize the heat shock response of bat against a mammalian proxy mice, in vivo heat shock was performed on animals and subsequent organ was harvested for bulk sequencing at multiple time points. Ctl – Baseline of animals, prior to treatment. Hs – Animals immediately after 1h in vivo heat shock treatment. R - Animals undergone 1h invivo heat shock treatment followed by 4h of recovery. The following organs were harvested: lung (lg), blood (bl) and muscle (mc).