Natures wonders: C. elegans feels colors (Introduction)

by David Turell , Sunday, March 07, 2021, 14:43 (1355 days ago) @ David Turell

Senses wave lengths:

https://www.the-scientist.com/news-opinion/eyeless-worm-c-elegans-perceives-colors-stud...

"Yet C. elegans still harbors secrets, and a big one is unveiled today (March 4) in Science: this eyeless worm can, in a way, see, using color to help it discriminate between toxic and harmless bacteria when searching out food.

"Researchers have previously shown that C. elegans can sense some types of light, notes study coauthor Dipon Ghosh, a biology postdoc at MIT who started the project when he was a graduate student at Yale University. The new results show that the worms are “actually comparing ratios of wavelengths, and using that information to make decisions,” he says. “And that, I think, was completely surprising and unexpected.”

***

"In the wild, C. elegans favors environments such as rich soil and decomposing food heaps, where it feeds on bacteria. The worm is known to avoid munching on the poisonous species Pseudomonas aeruginosa, and the study came about, says Ghosh, because he was curious about how C. elegans does this. In reading studies relevant to the question, he learned that one of the toxins P. aeruginosa secretes is blue.

***

"While C. elegans avoided ordinary, unaltered P. aeruginosa, it didn’t shy away from either the nontoxic blue or the toxic, colorless version, leaving Ghosh confused. Ultimately, he found he could get the worms to avoid the toxic, colorless bacteria by shining blue-filtered light on their dishes—suggesting that color did indeed influence C. elegans’s foraging behavior.

"In further experiments, Ghosh discovered that he could affect the worms’ foraging behavior by varying the ratio of blue to amber light shining on their dishes. But when he ran the same test on dozens of wild strains of C. elegans, not all responded in the same way to the same ratios.

"Through genetic analyses, Ghosh and his colleagues identified two genes, jkk-1 and lec-3, that appear to be involved in the responses to color. Neither code for opsins, the class of light-sensitive proteins needed for vision in the eye; rather, the study’s authors suggest, they may be involved in light-influenced stress-response pathways."

Comment: P. aeruginosa is a nasty bug, can make humans very sick. Elegans had to have the ability to sense color to learn to avoid them. Where did that come from? Perhaps God.