The Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA.
The Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA.
Dev Biol. 2019 Oct 15;454(2):170-180. doi: 10.1016/j.ydbio.2019.06.009. Epub 2019 Jun 23.
Phenotypic plasticity allows animals to survive in changing environments through the alteration of phenotypes or development. One of the best-studied examples of phenotypic plasticity is dauer larval development in the free-living roundworm Caenorhabditis elegans. When faced with hostile environments, C. elegans larvae can exit reproductive development and enter the stress-resistant and spore-like dauer larval stage. However, knowledge about how the dauer entry decision is made, and how the different tissues of the animal coordinate to execute transformation into dauer, is limited. This is because identifying animals that make the entry decision, or that fail to coordinately remodel their tissues during dauer development, is time-consuming and labor-intensive. Utilizing our previously reported RNA-seq of animals going through dauer or reproductive development (Lee et al., 2017), we have identified genetic markers for conveniently tracking and manipulating the dauer entry decision. These include col-183 (which tracks dauer fate in the hypodermis), ets-10 (neurons and intestine), nhr-246 (intestine and hypodermis), and F53F1.4 (reproductive fate in the hypodermis). Using condition shift experiments, we demonstrate that the dauer-specific fluorescent expression of the markers correspond to the commitment event of the dauer entry decision, and therefore label when the decision is made. We show that these markers can be used to manipulate the entry decision by driving the reproduction-promoting gene daf-9 under the control of the dauer-specific marker col-183, through which we could shift animals into non-dauer development. We further demonstrate that the markers can be used to track tissue coordination during the decision. daf-9, daf-15, and daf-18 partial dauers exhibit incomplete expression of the ets-10 marker, with our results indicating that the same gene (e.g. daf-9 or daf-18) can affect dauer development differently in different tissues. Our findings provide molecular tools for studying phenotypic plasticity during a whole animal decision.
表型可塑性允许动物通过改变表型或发育来在不断变化的环境中生存。表型可塑性的最佳研究实例之一是自由生活的秀丽隐杆线虫的 dauer 幼虫发育。当面临恶劣环境时，C. elegans 幼虫可以退出生殖发育并进入抗逆性和孢子状 dauer 幼虫阶段。然而，关于 dauer 进入决策是如何做出的，以及动物的不同组织如何协调转变为 dauer 的知识是有限的。这是因为鉴定做出进入决策的动物，或者在 dauer 发育过程中未能协调重塑其组织的动物，既耗时又费力。利用我们之前报道的进行 dauer 或生殖发育的动物的 RNA-seq（Lee 等人，2017），我们已经确定了用于方便跟踪和操纵 dauer 进入决策的遗传标记。这些标记包括 col-183（在皮下组织中跟踪 dauer 命运）、ets-10（神经元和肠）、nhr-246（肠和皮下组织）和 F53F1.4（皮下组织中的生殖命运）。通过条件转换实验，我们证明标记物的 dauer 特异性荧光表达与 dauer 进入决策的承诺事件相对应，因此标记了决策做出的时间。我们表明，这些标记物可以通过在 dauer 特异性标记物 col-183 的控制下驱动促进生殖的基因 daf-9 来操纵进入决策，通过这种方式我们可以将动物转移到非 dauer 发育中。我们进一步证明，这些标记物可用于在决策过程中跟踪组织协调。daf-9、daf-15 和 daf-18 部分 dauer 表现出 ets-10 标记物的不完全表达，我们的结果表明相同的基因（例如 daf-9 或 daf-18）可以在不同的组织中以不同的方式影响 dauer 发育。我们的研究结果为研究整个动物决策过程中的表型可塑性提供了分子工具。
