Sieriebriennikov Bogdan, Sommer Ralf J
Max Planck Institute for Developmental Biology, Department of Integrative Evolutionary Biology, Tübingen, Germany.
Front Genet. 2018 Sep 11;9:382. doi: 10.3389/fgene.2018.00382. eCollection 2018.
In the last decade, case studies in plants and animals provided increasing insight into the molecular mechanisms of developmental plasticity. When complemented with evolutionary and ecological analyses, these studies suggest that plasticity represents a mechanism facilitating adaptive change, increasing diversity and fostering the evolution of novelty. Here, we summarize genetic, molecular and evolutionary studies on developmental plasticity of feeding structures in nematodes, focusing on the model organism and its relatives. Like its famous cousin , reproduces as a self-fertilizing hermaphrodite and can be cultured in the laboratory on indefinitely with a four-day generation time. However, in contrast to , worms show more complex feeding structures in adaptation to their life history. nematodes live in the soil and are reliably found in association with scarab beetles, but only reproduce after the insects' death. Insect carcasses usually exist only for a short time period and their turnover is partially unpredictable. Strikingly, worms can have two alternative mouth-forms; animals are either stenostomatous (St) with a single tooth resulting in strict bacterial feeding, or alternatively, they are eurystomatous (Eu) with two teeth allowing facultative predation. Laboratory-based studies revealed a regulatory network that controls the irreversible decision of individual worms to adopt the St or Eu form. These studies revealed that a developmental switch controls the mouth-form decision, confirming long-standing theory about the role of switch genes in developmental plasticity. Here, we describe the current understanding of mouth-form regulation. In contrast to plasticity, robustness describes the property of organisms to produce unchanged phenotypes despite environmental perturbations. While largely opposite in principle, the relationship between developmental plasticity and robustness has only rarely been tested in particular study systems. Based on a study of the Hsp90 chaperones in nematodes, we suggest that robustness and plasticity are indeed complementary concepts. Genetic switch networks regulating plasticity require robustness to produce reproducible responses to the multitude of environmental inputs and the phenotypic output requires robustness because the range of possible phenotypic outcomes is constrained. Thus, plasticity and robustness are actually not mutually exclusive, but rather complementary concepts.
在过去十年中，对植物和动物的案例研究让我们对发育可塑性的分子机制有了越来越深入的了解。当与进化和生态分析相结合时，这些研究表明，可塑性是一种促进适应性变化、增加多样性并推动新特性进化的机制。在这里，我们总结了关于线虫进食结构发育可塑性的遗传、分子和进化研究，重点关注模式生物及其亲属。与其著名的近亲一样，以自体受精的雌雄同体方式繁殖，并且可以在实验室中以四天的世代时间在[具体物质]上无限期培养。然而，与[近亲名称]不同的是，[线虫名称]的蠕虫在适应其生活史时表现出更复杂的进食结构。[线虫名称]线虫生活在土壤中，并且确实与金龟子甲虫有关联，但仅在昆虫死亡后才繁殖。昆虫尸体通常只存在很短的时间，并且它们的更替在一定程度上是不可预测的。引人注目的是，[线虫名称]的蠕虫可以有两种不同的口器形式；动物要么是具有单齿的窄口型（St），导致严格的细菌摄食，要么是具有双齿的宽口型（Eu），允许兼性捕食。基于实验室的研究揭示了一个调控网络，该网络控制个体蠕虫采用St或Eu形式的不可逆决定。这些研究表明，一个发育开关控制着口器形式的决定，证实了关于开关基因在发育可塑性中作用的长期理论。在这里，我们描述了目前对[线虫名称]口器调控的理解。与可塑性相反，稳健性描述了生物体在环境扰动下产生不变表型的特性。虽然原则上两者在很大程度上是相反的，但发育可塑性和稳健性之间的关系在特定研究系统中很少被测试。基于对线虫中热休克蛋白90（Hsp90）伴侣蛋白的研究，我们认为稳健性和可塑性确实是互补的概念。调节可塑性的遗传开关网络需要稳健性来对大量环境输入产生可重复的反应，并且表型输出也需要稳健性，因为可能的表型结果范围是受限的。因此，可塑性和稳健性实际上并非相互排斥，而是互补的概念。
