Schumann Isabell, Triphan Tilman
Department of Genetics, Institute of Biology, Faculty of Life Science, Leipzig University, Leipzig, Germany.
Front Behav Neurosci. 2020 Dec 16;14:612313. doi: 10.3389/fnbeh.2020.612313. eCollection 2020.
The post-embryonal development of arthropod species, including crustaceans and insects, is characterized by ecdysis or molting. This process defines growth stages and is controlled by a conserved neuroendocrine system. Each molting event is divided in several critical time points, such as pre-molt, molt, and post-molt, and leaves the animals in a temporarily highly vulnerable state while their cuticle is re-hardening. The molting events occur in an immediate ecdysis sequence within a specific time window during the development. Each sub-stage takes only a short amount of time, which is generally in the order of minutes. To find these relatively short behavioral events, one needs to follow the entire post-embryonal development over several days. As the manual detection of the ecdysis sequence is time consuming and error prone, we designed a monitoring system to facilitate the continuous observation of the post-embryonal development of the fruit fly . Under constant environmental conditions we are able to observe the life cycle from the embryonic state to the adult, which takes about 10 days in this species. Specific processing algorithms developed and implemented in Fiji and R allow us to determine unique behavioral events on an individual level-including egg hatching, ecdysis and pupation. In addition, we measured growth rates and activity patterns for individual larvae. Our newly created RPackage PEDtracker can predict critical developmental events and thus offers the possibility to perform automated screens that identify changes in various aspects of larval development. In conclusion, the PEDtracker system presented in this study represents the basis for automated real-time staging and analysis not only for the arthropod development.
包括甲壳类动物和昆虫在内的节肢动物物种的胚后发育以蜕皮为特征。这个过程定义了生长阶段，并由一个保守的神经内分泌系统控制。每次蜕皮事件都分为几个关键时间点，如蜕皮前、蜕皮期和蜕皮后，并且在动物的角质层重新硬化时，会使它们暂时处于高度脆弱的状态。蜕皮事件在发育过程中的特定时间窗口内以即时蜕皮序列发生。每个子阶段只持续很短的时间，通常以分钟为单位。为了找到这些相对较短的行为事件，需要跟踪几天内的整个胚后发育过程。由于手动检测蜕皮序列既耗时又容易出错，我们设计了一个监测系统，以方便对果蝇的胚后发育进行连续观察。在恒定的环境条件下，我们能够观察从胚胎状态到成虫的生命周期，在这个物种中大约需要10天。在Fiji和R中开发并实施的特定处理算法使我们能够在个体水平上确定独特的行为事件，包括卵孵化、蜕皮和化蛹。此外，我们测量了单个幼虫的生长速率和活动模式。我们新创建的R包PEDtracker可以预测关键的发育事件，从而提供了进行自动筛选的可能性，以识别幼虫发育各个方面的变化。总之，本研究中提出的PEDtracker系统不仅代表了节肢动物发育自动实时分期和分析的基础。
