Category Archives: Biological sciences

From the “cool things to do with glowing animals” department:

What do light-emitting squid have to do with your gut?  Unless you lunched on some really exotic calamari, I’m talking about symbiotic animal-bacteria relationships.

Researchers at UW-Madison are taking advantage of the symbiotic relationship between the Hawaiian bobtail squid and a luminescent bacteria, Vibrio fischeri, as a model for beneficial microbe-host interactions like those that help us digest our food and regulate our immune systems.  Humans host thousands of bacterial species, the vast majority of which are innocuous or even beneficial.  Only a handful pose a threat.  So what sets a platonic relationship apart from a pathogenic one?

A new paper out this week in the Proceedings of the National Academy of Sciences suggests the answer lies not with the bacteria, but with the host itself.  Researchers identify a slew of microbe-induced genetic changes in the tiny squid, including a set of evolutionarily conserved genes that may hold the secrets to developing a mutually beneficial relationship.

The results – including the involvement of several genes typically associated with responses to bacterial infection – suggest we may need to rethink our understanding of the main purpose of the immune system, according to the lead scientist.  Perhaps the common signaling pathways we think of as “anti-pathogen” pathways actually evolved as symbiosis pathways.

Take a moment to appreciate your resident microbe community, and read the full story.

Shrewed survivor

From Vanderbilt’s Exploration online mag comes this dispatch (excerpts below) about the pound-for-pound audaciousness of the water shrew. The zine includes great high-speed video of the creature’s hunting prowess.
The scientist, Ken Catania, is a former MacArthur Fellow … and slightly resembles a woodland creature himself. Exploration previously reported on his groundbreaking work (ahem) with the starnosed mole.

The research reveals that the small animal possesses remarkably sophisticated methods for detecting prey that allow it to catch small fish and aquatic insects as readily in the dark as in daylight.

It is a skill set that the water shrew really needs. About half the size of a mouse, water shrews have such a high metabolism that they must eat more than their weight daily and can starve to death in half a day if they can’t find anything to eat. As a result, water shrews are formidable predators ounce for ounce.

“Water shrews do much of their hunting at night, so I began wondering how they can identify their prey in nearly total darkness,” says Ken Catania, the associate professor of biological sciences at Vanderbilt who headed the study.

Catania teamed up with James Hare and Kevin Campbell at the University of Manitoba and used a high-speed infrared video camera to answer this question. The results of their study are reported in a paper titled “Water shrews detect movement, shape, and smell to find prey underwater” published Jan. 9 in the Proceedings of the National Academy of Sciences.

“Our research confirms that shrews in general, and water shrews in particular, are marvels of adaptation, with specializations and behaviors that put many other mammals to shame,” says Catania.
Its hunting methods are pretty amazing, and all without a 12-pack of cheap beer.