Ducoff H S, Jayaraman S, Blumenthal L K
Br J Cancer Suppl. 1984;6:249-52.
Delay in pupariation of irradiated fly (and other insect) larvae results from a neuroendocrine disturbance and represents a dose-dependent response of differentiated postmitotic tissue. Many experimental manipulations (e.g. heating) may themselves upset timing, limiting usefulness of this phenomenon as a model of postmitotic tissue response. Doses greater than 20 Gy inhibit retraction of specific muscles at time of pupariation, leading to formation of elongate puparia. Degree of elongation (ratio of length: breadth) was also a function of dose. Peak sensitivity for elongation occurs later than that for delay, but both endpoints exhibit rapid kinetics for sparing effect of dose fractionations (sdf). With degree of elongation as endpoint, we demonstrated synergism between heat and radiation, and heat markedly inhibited sdf. Maintenance of irradiated larvae under wet conditions greatly prolonged the larval stage, and degree of elongation was reduced. This recovery, analogous to repair of potentially-lethal damage (PLD) in plateau-phase cell cultures, proceeds much more slowly than sdf.
受辐照果蝇（及其他昆虫）幼虫化蛹延迟是由神经内分泌紊乱导致的，代表了有丝分裂后分化组织的剂量依赖性反应。许多实验操作（如加热）本身可能会扰乱时间安排，限制了这一现象作为有丝分裂后组织反应模型的实用性。剂量大于20 Gy会抑制化蛹时特定肌肉的收缩，导致形成细长的蛹。伸长程度（长：宽比）也是剂量的函数。伸长的峰值敏感性出现的时间比延迟的峰值敏感性晚，但两个终点对剂量分割（sdf）的 sparing 效应都表现出快速动力学。以伸长程度为终点，我们证明了热与辐射之间的协同作用，且热显著抑制了sdf。在潮湿条件下饲养受辐照幼虫会大大延长幼虫期，且伸长程度会降低。这种恢复类似于平台期细胞培养中潜在致死损伤（PLD）的修复，其进行速度比sdf慢得多。
