Chicago -- U.S. scientists have discovered the first incidence in any species in which an entire enzyme system is found to be activated in only one sex.
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The researchers at the University of Illinois-Chicago, using nuclear magnetic resonance imaging, found a chemical compound in male blue crabs that is not present in female blue crabs.
Although hormone level differences are generally believed the primary cause of variation between the sexes in animal and human development, the existence of a sex-specific metabolite is a previously unrecognized and potentially significant biochemical phenomenon, said Robert Kleps, director of the university's Research Resource Center and lead author of the study.
"It's possible to speculate that the presence or absence of a sex-specific metabolite might affect an animal's development, anatomy and biochemistry," Kleps said, adding differences between the sexes such as susceptibility to heart disease or average life span might be due to the presence or absence of a metabolite.
Kleps said researchers might review metabolic studies in other animals, including humans, to look for a sex-specific metabolite that might have escaped notice in the variation among individuals.
The study appears in the online journal PLoS One.
Copyright 2007 by United Press International.