Golden J W, Riddle D L
Dev Biol. 1984 Apr;102(2):368-78. doi: 10.1016/0012-1606(84)90201-x.
Three environmental cues influence both the entry into and exit from the developmentally arrested dispersal stage called the dauer larva: a dauer-inducing pheromone, food, and temperature. The pheromone, which is a measure of population density, induces dauer larva formation at the second (L2) molt and inhibits recovery in a dose-dependent manner. Food acts competitively to reduce the frequency of dauer larva formation and to enhance recovery. The pheromone causes a specific extension of the second larval stage, coupled with a transient decrease in the growth rate of the L2. Second-stage larvae grown in the presence of added pheromone are morphologically distinguishable from L2 larvae grown without pheromone. We have named the pre-dauer L2 larva the L2d. Commitment to dauer larva formation can occur at the L2d molt. When L2d larvae are shifted out of pheromone to a lawn of E. coli just before the L2d molt, a few worms complete development into dauer larvae. In contrast, worms are essentially committed to the non-dauer life cycle by the first larval molt if the L1 larvae are not grown in appropriately high levels of pheromone. In the presence of pheromone, the percentage of dauer larva formation is enhanced at higher temperatures within the normal growth range. Temperature down-shifts induce dauer larva recovery. Temperature-shift experiments show that the enhancement of dauer larva formation requires exposure to the higher temperature around the L1 molt. Two sensory mutants defective in thermotaxis are altered in their sensitivity to the dauer-inducing pheromone, but their pheromone response retains temperature dependence. Response of dauer larvae to environmental cues is highly age dependent, with older dauer larvae exhibiting an increased tendency to recover.
三种环境信号会影响发育停滞的扩散阶段（即 dauer 幼虫）的进入和退出：一种诱导 dauer 形成的信息素、食物和温度。这种信息素是种群密度的一种度量，它在第二次（L2）蜕皮时诱导 dauer 幼虫形成，并以剂量依赖的方式抑制恢复。食物具有竞争性作用，可降低 dauer 幼虫形成的频率并促进恢复。信息素会导致第二幼虫阶段的特定延长，同时 L2 的生长速率会短暂下降。在添加信息素的情况下生长的第二阶段幼虫在形态上与未添加信息素时生长的 L2 幼虫不同。我们将 dauer 前的 L2 幼虫命名为 L2d。在 L2d 蜕皮时可能会决定形成 dauer 幼虫。当 L2d 幼虫在 L2d 蜕皮前从信息素环境转移到大肠杆菌菌苔上时，少数蠕虫会发育成 dauer 幼虫。相比之下，如果 L1 幼虫不是在适当高水平的信息素中生长，那么在第一次幼虫蜕皮时，蠕虫基本上就会进入非 dauer 生命周期。在信息素存在的情况下，在正常生长范围内，较高温度会提高 dauer 幼虫形成的百分比。温度下降会诱导 dauer 幼虫恢复。温度转换实验表明，dauer 幼虫形成的增强需要在 L1 蜕皮前后暴露于较高温度下。两个在趋温性方面有缺陷的感觉突变体对诱导 dauer 形成的信息素的敏感性发生了改变，但它们对信息素的反应仍保留温度依赖性。dauer 幼虫对环境信号的反应高度依赖年龄，年龄较大的 dauer 幼虫恢复的倾向增加。
