London. July 25 : Worms not only use pheromones to send mating signals to each other, but as it turns out, they use it the complex chemical code as a cur for hibernation as well.
The scientists from the University of Florida, Cornell University, the California Institute of Technology and the U.S. Department of Agriculture focussed their study on the tiny worm Caenorhabditis elegans.
While at lower levels, the pheromone directs the male C. elegans to mate with its partner, but in case the worm population grows and the food supply falls, it leads to an increase in the chemical signal and the cue changes from mate to hibernate.
Arthur Edison, Ph.D., one of the study's senior authors said that with this discovery, researchers would be able to find solutions of how to combat more harmful worms that destroy crops and provide clues for scientists studying similar parasite worms.
"Even though it's the same compound, it affects different behaviours. It's two different life traits converging," Nature quoted Fatma Kaplan, Ph.D., one of the study's lead authors, as saying. In 2002, Cal Tech researcher Paul Sternberg, Ph.D., did find out that male C. elegans were attracted to a signal sent out by the opposite sex, but they weren't sure exactly what it was.
Usually C. elegans worms are either male or hermaphrodite and in order to know how they communicate, UF researchers took out the chemicals secreted by the hermaphrodites and tested them on male worms.
In the initial tests, it was found that the males were attracted to the secretions when the hermaphrodites were fertile. The researchers used mass spectroscopy and nuclear magnetic resonance spectroscopy - including a UF- and National High Magnetic Field Laboratory-developed NMR probe that allows researchers to test extremely small amounts - to isolate the three chemicals in these secretions that are believed to cause the mating signal.
On individual testing, the chemicals produced little to no response. However, Edison said that the chemicals strongly attracted male worms when they worked in synergy with each other.
However, he said that it was just chance collaboration with Cornell researcher Frank Schroeder, Ph.D., that led to the paper's biggest finding. Schroeder had recently discovered the dauer pheromone. These chemicals signal worms to enter a hibernation phase when the food supply is low.
It was found that Schroeder's hibernation pheromone and the UF-discovered mating pheromone were almost identical. And after testing in worms, it was revealed that mating pheromones also act as a dauer pheromones at high concentrations.
"It's like a bell-shaped curve. If (the pheromone level is) too low, it doesn't work. If you add more, you get a nice mating response. If it gets high, the mating response stops and they go into hibernation mode. It makes nice ecological sense that (one compound) could be doing both jobs," said Edison.
He added: "But before this work, nobody in the whole history of C. elegans research had associated dauer formation with mating. Now these small molecules link the two behaviours.
The study was published in the latest issue of journal Nature.