Research tells us that the “good” bacteria that inhabit our intestines help to regulate our metabolism. A new study in fruit flies shows one of the ways in which these commensal microbes keep us metabolically fit.
The findings, published today in Cell Metabolism, suggest that innate immune pathways, our first line of defense against bacterial infection, have a side job that’s equally important.
The intestine’s digestive cells use an innate immune pathway to respond to harmful bacteria by producing antimicrobial peptides. But other intestinal cells, enteroendocrine cells, use the same pathway, known as IMD, to respond to “good” bacteria — by fine-tuning body metabolism to diet and intestinal conditions.
“What’s most interesting to me is that some innate immune pathways aren’t just for innate immunity,” says Paula Watnick, MD, PhD, of the Division of Infectious Diseases at Boston Children’s Hospital. “Innate immune pathways are also listening to the ‘good’ bacteria – and responding metabolically.” …
When Dr. Jonathan Kagan’s student came to him complaining of dying fruit flies, the two were unaware that their research was about to take an unexpected turn. Their goal in establishing Drosophila lines had been to study virus-host interactions. It was quickly subverted when the flies died on exposure to carbon dioxide, used when transferring flies between vials.
This was surprising on two fronts. First, carbon dioxide is routinely used to anesthetize the flies, with no ill effects. Second, the uninfected flies did not die. The virus used to infect the flies, called vesicular stomatitis virus (VSV), normally does not cause symptoms, even with the virus making several thousand copies of itself. …
If you have children present, you might want to click out of this post. But if you want to understand motivation, you’ll want to know about the sexual behavior of fruit flies.
In the brain, motivational states are nature’s way of matching our behaviors to our needs and priorities. But motivation can go awry, and dysfunction of the brain’s motivation machinery may well underlie addiction and mood disorders, says Michael Crickmore, PhD, a researcher in the F.M. Kirby Neurobiology Center. “Basically, every behavior or mood disorder is a disorder of motivation,” he says.
It’s already known that brain cells that communicate via the chemical dopamine are important in motivation—and are also implicated in ADHD, depression, schizophrenia and addiction. But what exactly are these cells up to, and who are they talking to? That’s where fruit flies come in.
“We study motivation in a simple system that we can bash very hard,” says Crickmore. …