Food 0, Sex 1

In a study that will probably elicit a collective “duh” from the average college student, researchers have discovered that male brains – at least in nematodes – are wired to ignore food so that they can instead focus on searching for a mate.

While the findings – which appear today in the journal Current Biology – may be punchline fodder, the science behind the discovery provides researchers with new insight into biological mechanisms that may dictate the difference in behavior between males and females.  Specifically, it points to sex-specific genetic regulation of cells in the nervous system. 

The research, which was led by Douglas Portman, Ph.D., with the Department of Biomedical Genetics and Center for Neural Development and Disease, was conducted using C. elegans, a microscopic roundworm that – like the fruit fly Drosophila – has long been a research tool used by scientists to understand basic biological principals that, in many cases, apply throughout the animal kingdom. Important foundational biomedical findings like programmed cell death and RNA interference were first made in experiments involving C. elegans.

C. elegans is particularly useful in studying the nervous system because scientists have mapped and understand in great detail the function and connections of every one of C. elegans 302 neurons.

It has long been observed that male C. elegans will leave a food source and wander in search of a mate.  Hermaphrodites (modified females), on the other hand, will stay at a food source.  Portman and his colleagues discovered that males express less of a receptor called ODR-10.  This receptor is responsible for detecting “scents” and is present on the worm’s olfactory neurons.  By having fewer of these receptors, the male brain essentially dials down the ability to smell and find food, prompting it to leave or ignore nourishment while it looks for a breading partner.

In a series of experiments, the researchers showed that this was not only the case (males would successfully navigate an obstacle course full of food distractions to find a mate), but that they could change the behaviors in males and hermaphrodites by altering the expression of ODR-10.  

You can read more about the study here.