In a world of myriad milks, from cow to oat, we now have worm milk. This is no dairy substitute for human consumption, but rather a substance that worm parents secrete to their offspring in an act of reproductive death, or sacrificing their life to nurture children. For years researchers have observed worms produce this goo and perish, but now they understand why: It’s milk—well, it used to be the worm’s intestines secreted through the vulva—that feeds offspring. Further, this discovery has an intriguing connection to past research done on C. elegans that increased their lifespan by tenfold.
The study, published last week in the journal Nature Communications, examines this self-destructive, lactation-like process in C. elegans, one-millimeter transparent roundworms. The researchers, all from University College London’s Institute of Healthy Aging, studied how the known process of venting one’s intestines is associated with chemical pathways that control the aging process.
“The real interesting side of it is that this milk is being produced at a cost,” says Carina Kern, the study’s first author. That cost is that these nematodes hemorrhage their intestines, now a yolky milk, through the vulva, and then they expire so their children may live.
Worms are hermaphrodites, meaning they possess male and female anatomy. So a worm can fertilize itself, but it runs out of sperm before it runs out of eggs. Once it runs out of sperm, it will expel its remaining unfertilized eggs and self-destruct since it can’t reproduce anymore. These worms in particular are semelparous organisms, meaning they reproduce only once (unlike humans and other mammals, which can reproduce multiple times in a lifetime). Many semelparous organisms also experience reproductive death, like Pacific salmon and the marsupial antechinus.
One of the most interesting aspects of this study is the implication with aging. Kern says that starting in the 1980s, researchers in aging studies discovered that suppressing the insulin pathway in C. elegans increased the worms’ lifespan up to tenfold. That gene happens to also control this reproductive death. So, when the gene for creating this milk-yolk is switched off, the parent worm doesn’t produce it, and therefore doesn’t perish immediately after.
Kern says the nematodes are healthier and long