Section of Organismal, Integrative and Systems Biology, School of Life Sciences, Arizona State University, Tempe, AZ 8587-4501, USA.
J Exp Biol. 2011 May 1;214(Pt 9):1419-27. doi: 10.1242/jeb.051904.
Animals reared in hypoxic environments frequently exhibit smaller body sizes than when reared under normal atmospheric oxygen concentrations. The mechanisms responsible for this widely documented pattern of body size plasticity are poorly known. We studied the ontogeny of responses of Drosophila melanogaster adult body size to hypoxic exposure. We hypothesized that there may be critical oxygen-sensitive periods during D. melanogaster development that are primarily responsive to body size regulation. Instead, our results showed that exposure to hypoxia (an atmospheric partial pressure of oxygen of 10 kPa) during any developmental stage (embryo, larvae and pupae) leads to smaller adult size. However, short hypoxic exposures during the late larval and early pupal stages had the greatest effects on adult size. We then investigated whether the observed reductions in size induced by hypoxia at various developmental stages were the result of a decrease in cell size or cell number. Abdominal epithelial cells of flies reared continuously in hypoxia were smaller in mean diameter and were size-limited compared with cells of flies reared in normoxia. Flies reared in hypoxia during the embryonic, larval or pupal stage, or during their entire development, had smaller wing areas than flies reared in normoxia. Flies reared during the pupal stage, or throughout development in hypoxia had smaller wing cells, even after controlling for the effect of wing size. These results suggest that hypoxia effects on the body size of D. melanogaster probably occur by multiple mechanisms operating at various developmental stages.
在低氧环境中饲养的动物通常比在正常大气氧浓度下饲养的动物体型小。导致这种广泛记录的体型可塑性模式的机制知之甚少。我们研究了黑腹果蝇成体体型对低氧暴露的发育反应。我们假设在黑腹果蝇的发育过程中可能存在关键的氧敏感时期，主要对体型调节起反应。然而，我们的结果表明，在任何发育阶段（胚胎、幼虫和蛹）暴露于低氧（氧分压为 10 kPa）都会导致成虫体型较小。然而，在晚期幼虫和早期蛹期进行短暂的低氧暴露对成虫体型的影响最大。然后，我们研究了在不同发育阶段由低氧引起的大小减小是否是细胞大小或细胞数量减少的结果。在低氧中连续饲养的果蝇的腹部上皮细胞平均直径较小，与在常氧中饲养的细胞相比受到大小限制。在常氧中饲养的果蝇的翅膀面积比在常氧中饲养的果蝇小。在低氧中饲养的果蝇在胚胎、幼虫或蛹期，或在整个发育过程中，其翅膀细胞较小，即使在控制了翅膀大小的影响后也是如此。这些结果表明，低氧对黑腹果蝇体型的影响可能通过在不同发育阶段起作用的多种机制发生。
