| Description: |
In response to the environment, the nematode C. elegans must choose between arrest at a long-lived alternate third larval stage, the dauer diapause, or reproductive development. This decision may ultimately be mediated by daf-9 , a cytochrome P450 related to steroidogenic hydroxylases and its cognate nuclear receptor daf-12 , implying organism-wide coordination by lipophilic hormones. Accordingly, here we show that daf-9(+) works cell non-autonomously to bypass diapause, and promote gonadal outgrowth. Among daf-9 -expressing cells, the hypodermis is most visibly regulated by environmental inputs, including dietary cholesterol. On in reproductive growth, off in dauer, hypodermal daf-9 expression is strictly daf-12 dependent, suggesting feedback regulation. Expressing daf-9 constitutively in hypodermis rescues dauer phenotypes of daf-9 , as well as insulin/IGF receptor and TGFβ mutants, revealing that daf-9 is an important downstream point of control within the dauer circuits. This study illuminates how endocrine networks integrate environmental cues and transduce them into adaptive life history choices. |