First finding of a metabolite in ...( Researchers at the University of Ill...)

Researchers at the University of Illinois at Chicago have discovered a chemical compound in male blue crabs that is not present in females -- the first time in any species that an entire enzyme system has been found to be activated in only one sex.

The research, performed using nuclear magnetic resonance, was published online Aug. 22 in PLoS ONE, the peer-reviewed, open-access resource from the Public Library of Science.

Although hormone level differences are generally accepted as 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, according to Robert Kleps, director of the UIC Research Resource Center NMR Lab 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. 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, he said.

Now that the existence of a sex-specific metabolite has been proved for one animal, Kleps says researchers might review metabolic studies in other animals, including humans, to look for the presence of a sex-specific metabolite that might have escaped notice in the variation among individuals.

Using primarily phosphorus-31 NMR, with the capability of analyzing whole tissue, Kleps observed an unusual signal in the gill tissue of male blue crabs that was absent in females.

NMR can be measured in the nuclei of certain isotopes, including hydrogen-1, carbon-13 and phosphorus-31, whose atoms resonate at characteristic frequencies in a magnetic field. The exact frequency is slightly changed by the atom's chemical micro-environment within a particular molecule.

The researchers found in male gill tissue
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