School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154-4004, USA.
J Exp Biol. 2023 Sep 15;226(18). doi: 10.1242/jeb.246144. Epub 2023 Sep 29.
Previous studies have shown that selection for starvation resistance in Drosophila melanogaster results in delayed eclosion and increased adult fat stores. It is assumed that these traits are caused by the starvation selection pressure, but its mechanism is unknown. We found that our starvation-selected (SS) population stores more fat during larval development and has extended larval development and pupal development time. Developmental checkpoints in the third instar associated with ecdysteroid hormone pulses are increasingly delayed. The delay in the late larval period seen in the SS population is indicative of reduced and delayed ecdysone signaling. An enzyme immunoassay for ecdysteroids (with greatest affinity to the metabolically active 20-hydroxyecdysone and the α-ecdysone precursor) confirmed that the SS population had reduced and delayed hormone production compared with that of fed control (FC) flies. Feeding third instar larvae on food supplemented with α-ecdysone partially rescued the developmental delay and reduced subsequent adult starvation resistance. This work suggests that starvation selection causes reduced and delayed production of ecdysteroids in the larval stage and affects the developmental delay phenotype that contributes to subsequent adult fat storage and starvation resistance.
先前的研究表明，在黑腹果蝇中选择抗饥饿能力会导致出蛹延迟和成年脂肪储存增加。人们认为这些特征是由饥饿选择压力引起的，但具体机制尚不清楚。我们发现，我们的饥饿选择（SS）种群在幼虫发育过程中储存更多的脂肪，并且延长了幼虫发育和蛹发育时间。与蜕皮激素脉冲相关的第三龄的发育检查点被逐渐延迟。SS 种群中晚期幼虫期的延迟表明蜕皮激素信号的减少和延迟。针对蜕皮激素（与代谢活跃的 20-羟基蜕皮激素和α-蜕皮激素前体具有最大亲和力）的酶免疫测定法证实，与喂食对照（FC）蝇相比，SS 种群的激素产生减少且延迟。用补充有α-蜕皮激素的食物喂养第三龄幼虫部分挽救了发育延迟，并降低了随后的成年饥饿抗性。这项工作表明，饥饿选择导致幼虫期蜕皮激素的产生减少和延迟，并影响发育延迟表型，从而导致随后的成年脂肪储存和饥饿抗性增加。
