C. elegans provide "milk" for their young

The nematode Caenorhabditis elegans exhibits rapid senescence that is promoted by the insulin/IGF-1 signaling (IIS) pathway via regulated processes that are poorly understood. IIS also promotes production of yolk for egg provisioning, which in post-reproductive animals continues, supported by destructive repurposing of intestinal biomass that contributes to senescence. Post-reproductive mothers vent this yolk which can be consumed by larvae and promotes their growth. This implies that later yolk production is not futile; instead vented yolk functions similarly to milk. Moreover, yolk venting is promoted by IIS. That this process is promoted by IIS provides new insights into how and why IIS shortens lifespan in C. elegans. Fully-fed d4 hermaphrodites were allowed to vent for 30 min, and vented proteins analysed against excretory/secretory products collected for L3 larvae as a negative control.

秀丽隐杆线虫（Caenorhabditis elegans）表现出快速衰老表型，该过程由胰岛素/IGF-1信号通路（insulin/IGF-1 signaling, IIS）通过尚未完全阐明的调控过程所促进。IIS通路同时可促进用于卵子营养供给的卵黄合成；在生殖活动结束后的线虫体内，卵黄合成仍会持续，该过程依赖于肠道生物量的破坏性重编程，而这一过程会加速衰老进程。生殖后的母体会将卵黄排出体外，这些排出的卵黄可被幼虫摄取并促进其生长发育，这表明后期的卵黄产生并非无效的能量消耗：相反，排出的卵黄功能与哺乳动物的乳汁类似。此外，卵黄排出过程同样受IIS通路调控。这一发现为解析IIS通路如何以及为何会缩短秀丽隐杆线虫的寿命提供了全新视角。本实验将完全饱腹的第4天雌雄同体个体静置30分钟以完成卵黄排出，随后对收集到的排出蛋白质进行分析，并以取自三龄幼虫（L3 larvae）的排泄/分泌产物作为阴性对照。