BACKGROUND Previous studies have implicated a role for circadian clocks in regulating pre-adult development of organisms. Among them two approaches are most notable: 1) use of insects whose clocks have different free-running periods and 2) imposition of artificial selection on either rate of development, timing of emergence or circadian period in laboratory populations. Using these two approaches, influence of clock on rate of development has been elucidated. However, the contribution of circadian clocks in determining time taken for pre-adult development has remained unclear. Here we present results of our studies aimed to understand this influence by examining populations of fruit flies carrying three different alleles of the period gene and hence having different free-running periods. We tried to achieve similarity of genetic background among the three strains while also ensuring that they harbored sufficient variation on loci other than period gene. RESULTS We find that under constant conditions, flies with long period have slower development whereas in presence of light-dark cycles (LD) of various lengths, the speed of development for each genotype is influenced by whether their eclosion rhythms can entrain to them. Under LD 12:12 (T24), where all three strains entrain, they do not show any difference in time taken for emergence, whereas under LD 10:10 (T20) where long period flies do not entrain and LD 14:14 (T28) where short period flies do not entrain, they have slower and faster pre-adult development, respectively, compared to the controls. We also show that a prior stage in development namely pupation is not rhythmic though time taken for pupation is determined by both the environmental cycle and period allele. CONCLUSION We discuss how in presence of daily time cues, interaction of the cyclic environmental factors with the clock determines the position and width of the gate available for a fly to emerge (duration of time within a cycle when adult emergence can occur) resulting in an altered developmental duration from that observed under constant conditions. We also discuss the relevance of genetic background influencing this regulation.

中文翻译：

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环境周期通过昼夜节律时钟介导的成年门控调节发育时间。

背景技术先前的研究已经暗示了生物钟在调节生物的成年前发育中的作用。其中两种方法最为引人注目：1）使用时钟具有不同自由运行时间的昆虫，以及2）对实验室种群的发育速度，出苗时间或昼夜节律进行人工选择。使用这两种方法，已经阐明了时钟对发展速度的影响。然而，生物钟在确定成人发育所需时间方面的贡献仍不清楚。在这里，我们介绍了我们的研究结果，旨在通过检查带有时期基因的三个不同等位基因并因此具有不同自由运行时期的果蝇种群来了解这种影响。我们试图使这三株菌株的遗传背景具有相似性，同时还要确保它们在时期基因以外的基因座上具有足够的变异。结果我们发现，在恒定条件下，具有较长周期的果蝇发育较慢，而在存在各种长度的明暗循环（LD）的情况下，每种基因型的发育速度受其附子节律是否可以带入它们的影响。在LD 12:12（T24）下，所有三个毒株都夹带，它们的出苗时间没有显示出任何差异，而在LD 10:10（T20）下，长时蝇没有夹带，而LD 14:14（T28） ）与对照相比，短时蝇没有夹带，它们分别具有较慢和较快的成虫发育。我们还表明，发育的前一个阶段即化脓不是有节奏的，尽管化脓所花费的时间由环境周期和周期等位基因共同决定。结论我们讨论了在存在每日提示的情况下，周期性环境因素与时钟的相互作用如何确定可用于飞行的门的位置和宽度（当成年人出现时，一个周期内的时间长短）会导致飞行。与在恒定条件下观察到的发育持续时间不同。我们还讨论了遗传背景影响该法规的相关性。周期性环境因素与时钟之间的相互作用决定了苍蝇可以出门的位置和宽度（成年后可能出现的周期内的时间）导致了在恒定条件下观察到的发育时间发生了变化。我们还讨论了遗传背景影响该法规的相关性。周期性环境因素与时钟之间的相互作用决定了苍蝇可以出门的位置和宽度（成年后可能出现的周期内的时间）导致了在恒定条件下观察到的发育时间发生了变化。我们还讨论了遗传背景影响该法规的相关性。