Worms infected by bacteria often start showing signs of serious nerve damage in the brain. If a worm happens to be infertile, it can weather an infection without damage to its neurons. Scientists hope that figuring out why infertility and resistance to nerve damage are linked might help us someday fight human diseases like Alzheimer’s or Parkinsons.
Those are the findings of a recent study by scientists at Duke University, who have been raising varieties of mutated Caenorhabditis elegant (C. elegans) worms in dishes full of benign E. coli bacteria. When the worms matured, the scientists took away the E. coli, and replaced it with Pseudomonas aeruginosa, a relatively nasty strain of bacteria that left the worms with severe bacterial infections. Soon the worms started showing physical signs of neurodegeneration. Neurons curved and split. They grew round growths that made them look like beads.
Scientists have seen neurodegeneration associated with severe and long-lasting infections in humans. This study provides further evidence that there is a link between infection and neurodeterioration. It’s probably not a direct function of the bacteria so much as the nervous system’s reaction to an inflamed and stressed body.
But not all the worms had nerves that succumbed. Worms with mutated mes-1 genes suffered no degeneration despite their infection. Mes-1 genes are, ultimately, responsible for embryonic development. They position the spindle, the mechanism that separates chromosomes and places a copy of each chromosome in each daughter cell during cell division.
The mutation rendered the worms infertile—and the researchers believe that that is important. It’s a matter of limited resources. The worm has only so much energy, and the fact that the worm does not need to direct its energy into creating the next generation of worms means it could be using them to fight the damage a bacterial infection does to its neurons.
Though genetic infertility isn’t a “cure” for dreaded human diseases like Alzheimer’s and Parkinsons, the researchers hope that getting a better idea of what happens to the neuron during an infection, and how it can be protected from damage, might help us prevent neurological diseases in the future.
Image: Alejandro Aballay lab, Duke University