Researchers continue to investigate the link between germ cells and longevity in lower animals. In this open access paper, changes to fat metabolism are implicated as an important mechanism: "Removing the germ line of Caenorhabditis elegans extends its lifespan by approximately 60%. Eliminating germ cells also increases the lifespan of Drosophila, suggesting that a conserved mechanism links the germ line to longevity ... Reproduction and aging are two processes that seem to be closely intertwined. Experiments in Caenorhabditis elegans and Drosophila have shown that depletion of the germ line increases lifespan and that this process depends on insulin and lipophilic-hormone signaling. Recently, it was demonstrated that when germline stem cells (GSCs) cease to proliferate, fat metabolism is altered and this affects longevity. In this study, we have identified a nuclear hormone receptor, NHR-80, that mediates longevity through depletion of the germ line by promoting fatty acid desaturation. ... Our results reinforce the notion that fat metabolism is profoundly altered in response to GSC proliferation, and the data contribute to a better understanding of the molecular relationship between reproduction, fat metabolism, and aging."

Link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057950/