By Mark Michaud
New research published today in the journal Current Biology demonstrates how biological sex can modify communication between nerve cells and generate different responses in males and females to the same stimulus. The findings could new shed light on the genetic underpinnings of sex differences in neural development, behavior, and susceptibility to diseases.
"While the nervous systems of males and females are virtually identical, we know that there is a sex bias in how many neurological diseases manifest themselves, that biological sex can influence behavior in animals, and that some of these differences are likely to be biologically driven," said Douglas Portman, Ph.D., an associate professor in the Departments of Biomedical Genetics, Neuroscience, and the Center for Neurotherapeutics Discovery at the University of Rochester Medical Center (URMC) and lead author of the study. "This study demonstrates a connection between biological sex and the control and function of neural circuits and that these different sex-dependent configurations can modify behavior."
The findings were made in experiments involving the nematode C. elegans, a microscopic roundworm that has long been used by researchers to understand fundamental mechanisms in biology. Many of the discoveries made using these worms apply throughout the animal kingdom and this research has led to a broader understanding of human biology. In fact, three Nobel Prizes in medicine and chemistry have been awarded for discoveries involving C. elegans.
The study focuses on the different behaviors of male and female worms. There are two sexes of C. elegans, males and hermaphrodites. Although the hermaphrodites are able to self-fertilize, they are also mating partners for males, and are considered to be modified females.
The behavior of C. elegans is driven by sensory cues, primarily smell and taste, which are used by the worms to navigate their environment and communicate with each other. Female worms secrete a pheromone that is known to attract males who are drawn by this signal in search of a mate. Other females, however, are repelled by the same pheromone. It is not entirely understood why, but scientists speculate that that the pheromone signals to females to avoid areas where there may be too much competition.