1. Evolutionary Biology
  2. Genetics and Genomics
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Aging: A new defense in the battle of the sexes

  1. George L Sutphin  Is a corresponding author
  1. University of Arizona, United States
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Cite this article as: eLife 2019;8:e50140 doi: 10.7554/eLife.50140
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How self-sperm protects young hermaphrodite C. elegans from the damaging effects of seminal fluid during mating.

When male and hermaphrodite C. elegans roundworms mate, male sperm (blue) and seminal fluid (pale blue) mix with hermaphrodite self-sperm (grey). Nearly all oocytes are fertilized by male sperm rather than self-sperm following mating. The seminal fluid and self-sperm act on three signaling pathways that influence the health and longevity of C. elegans: an active sperm-sensing pathway is positive for the health of the roundworm, whereas active insulin and mTOR signaling pathways have negative effects on its health. Seminal fluid damages the health of roundworms because it activates both the insulin signaling pathway (through INS-7 and INS-8) and the mTOR signaling pathway (through a yet-to-be-discovered mechanism). Self-sperm, on the other hand, is good for the health of hermaphrodite roundworms because it activates the sperm-sensing pathway, and represses both the insulin signaling pathway (through the insulin peptide INS-37) and the mTOR signaling pathway (again through an unknown mechanism). Young hermaphrodites (top) have more self-sperm than old hermaphrodites (bottom), so they benefit from increased sperm-sensing signaling as well as reduced insulin and mTOR signaling. Old worms have less self-sperm to counter the adverse effects of seminal fluid, so they succumb to the negative consequences of insulin and mTOR signaling and die rapidly. The sperm-sensing pathway improves longevity by repressing the ephrin receptor VAB-1 and the transcription factor CEH-1. Activation of mTOR and insulin signaling removes two transcription factors that promote longevity (DAF-16 and HLH-30) from the cell nucleus, and translocates a transcription factor that reduces longevity (PQM-1) into the nucleus.

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