By Some fish have bacteria on the brain.
Wild and lab-grown members of the salmon family including European rainbow trout, Chinook salmon and Gila trout harbor active microbial communities inside their brains, researchers report September 18 in Science Advances. Lab-reared rainbow trout (Oncorhynchus mykiss) brains may source more than half of bacteria from their blood and guts, suggesting that microbes from other parts of the body traverse the blood-brain barrier to colonize the organ.
Animal brains are thought to be free of bacteria, with any invasion typically linked to disease (SN: 3/1/23). A growing body of work, for instance, shows that brain-infiltrating microbes may be linked with conditions such as Alzheimer’s disease in people. But the new finding hints that bacteria aren’t necessarily bad news for fish brains. For the most part, the animals seem healthy despite having microbes inside their skulls.
