Significant differentially expressed genes (DEG) for midgut tissue from bees maintained for four hours at 35°C or 45°C

Honey bee colonies in the United States have suffered from increased
die-off in the last few years with a complex set of interacting stresses
playing a key role. With changing climate, an increase in the frequency of
severe weather events, such as heat waves, is anticipated. Understanding
how these changes may contribute to stress in honey bees is crucial.
Individual honey bees appear to have a high capacity to endure thermal
stress. One reason for this high-level endurance is likely their robust
HSR which contributes to thermotolerance at the cellular level. However,
less is known about other mechanisms of thermotolerance, especially those
operating at the tissue level. To elucidate other determinants of this
resilience in this species, we used thermal stress coupled with RNAseq and
identified broad transcriptional remodeling of a number of key signaling
pathways in the honey bee, including those pathways known to be involved
in digestive tract regeneration in the fruit fly such as the Hippo and
JAK/STAT pathways. We also observe cell death and shedding of epithelial
cells, which likely leads to induction of this regenerative
transcriptional program. We found that thermal stress affects many of
these pathways in other tissues, suggesting a shared program of damage
response. This study provides important foundational characterization of
the tissue damage response program in this key pollinating species. In
addition, our data suggest that a robust regeneration program may also be
a critical contributor to thermotolerance at the tissue level, a
possibility which warrants further exploration in this and other species.

近年来，美国蜜蜂蜂群的死亡率持续攀升，多种相互作用的胁迫因子在其中发挥了关键作用。随着气候变化，热浪等极端天气事件的发生频率预计将有所增加。阐明此类环境变化如何加剧蜜蜂所受的胁迫，具有重要意义。
单个蜜蜂似乎具备较强的耐热胁迫能力，其背后的重要原因之一，可能是该物种拥有强大的热休克响应（Heat Shock Response, HSR）——该机制可在细胞层面提升机体的耐热性。然而，目前学界对其他耐热机制的了解仍较为有限，尤其是组织层面的耐热机制。
为阐明该物种抗逆性的其他决定因素，本研究将热胁迫与RNA测序（RNAseq）相结合，对蜜蜂体内的基因转录变化进行了系统分析，鉴定出多条关键信号通路发生了广泛的转录重塑，其中包括此前在果蝇中被证实参与消化道再生的通路，如Hippo通路与JAK/STAT通路。研究团队还观察到上皮细胞发生死亡并脱落，这一过程大概率诱导了再生相关的转录程序。我们同时发现，热胁迫在其他组织中也会对诸多此类通路产生影响，这提示蜜蜂体内存在一套共享的组织损伤响应程序。
本研究对这一关键授粉物种的组织损伤响应程序进行了重要的基础性表征。此外，本研究数据表明，一套高效的再生程序或许也是组织层面耐热性的关键促成因素，这一可能性值得在该物种及其他物种中开展进一步探究。