Visser Bertanne, Williams Caroline M, Hahn Daniel A, Short Clancy A, López-Martínez Giancarlo
Evolutionary Ecology and Genetics Group, Biodiversity Research Centre, Earth and Life Institute, Université catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium.
Department of Entomology and Nematology, College of Agriculture and Life Sciences, University of Florida, Gainesville, FL 32611, USA.
J Exp Biol. 2018 Mar 19;221(Pt 6):jeb167825. doi: 10.1242/jeb.167825.
Oxygen is essential for most animals, and exposure to a complete lack of oxygen, i.e. anoxia, can result in irreparable damage to cells that can extend up to the organismal level to negatively affect performance. Although it is known that brief anoxia exposure may confer cross-tolerance to other stressors, few data exist on the biochemical and organismal consequences of repeated intermittent bouts of anoxia exposure. In nature, the Caribbean fruit fly, (Diptera: Tephritidae), is frequently exposed to heavy tropical rainfall while pupating in the soil, equating to multiple exposures to hypoxia or anoxia during development. Here, we tested whether prior anoxia exposures during pupal development can induce a beneficial acclimation response, and we explored the consequences of prior exposure for both whole-organism performance and correlated biochemical metrics. Pharate adults (the last developmental stage in the pupal case) were most sensitive to anoxia exposure, showing decreased survival and fertility compared with controls. These negative impacts were ameliorated by exposure to anoxia in earlier pupal developmental stages, indicating a hormetic effect of prior anoxia exposure. Anoxia exposure early in pupal development reduced the oxygen debt repaid after anoxia exposure relative to pharate adults experiencing anoxia for the first time. Lipid levels were highest in all pupal stages when exposed to prior anoxia. Prior anoxia thus benefits organismal performance and relocates resources towards lipid storage throughout pupal-adult development.
氧气对大多数动物来说至关重要，暴露于完全缺氧的环境，即无氧环境，会对细胞造成无法修复的损伤，这种损伤甚至会扩展到机体层面，对机体表现产生负面影响。尽管已知短暂暴露于无氧环境可能会使机体对其他应激源产生交叉耐受性，但关于反复间歇性暴露于无氧环境的生化和机体影响的数据却很少。在自然界中，加勒比果蝇（双翅目：实蝇科）在土壤中化蛹时经常会遭遇热带暴雨，这相当于在发育过程中多次暴露于低氧或无氧环境。在此，我们测试了蛹发育期间先前的无氧暴露是否能诱导有益的适应性反应，并探讨了先前暴露对整个生物体表现以及相关生化指标的影响。羽化前成虫（蛹壳内的最后发育阶段）对无氧暴露最为敏感，与对照组相比，其存活率和繁殖力均有所下降。蛹发育早期暴露于无氧环境可减轻这些负面影响，这表明先前的无氧暴露具有 hormetic 效应。与首次经历无氧环境的羽化前成虫相比，蛹发育早期的无氧暴露减少了无氧暴露后偿还的氧债。在所有蛹期，先前暴露于无氧环境时脂质水平最高。因此，先前的无氧暴露有利于生物体表现，并在整个蛹到成虫的发育过程中将资源重新分配到脂质储存上。
