Scientists alter sexual orientatio...(thought the extra CEM neurons provided s...)

Date:10/25/2007

thought the extra CEM neurons provided sexual preference because fourth-stage males are not attracted to hermaphrodites but adult males are, Jorgensen says. We found instead that the brain which is the same in young males and hermaphrodites is rewired during the worm equivalent of puberty the fourth larval stage to make the males attracted to hermaphrodites.

What we show is that the shared nervous system [common between male and hermaphrodite] is broadly sexualized, and sexual attraction can be changed by essentially flipping a genetic switch in that common brain, he adds.

The study involved these key experiments:

-- The researchers used laser microsurgery to kill the male-only CEM neurons in young larval males. The resulting adult males still were attracted to hermaphrodites.

That suggests the core neurons brain cells common to both the male and hermaphrodite brain are sexualized, and that the extra CEM nerve cells found only in males are not necessary for sexual attraction even though they normally play a role in it.

-- The biologists zapped eight different kinds of nerve cells involved in the sense of smell and taste: the four kinds of CEM neurons found only in males and four kinds of core neurons (AWA and AWC) also found in hermaphrodites. If any of the eight types of neurons was damaged in adult males, attraction was impaired. But when the nerve cells were zapped before puberty in fourth-stage larvae, they grew into adults with normal attraction to hermaphrodites. That shows the nervous system can compensate for lost neurons as it goes through puberty, Jorgensen says.

Normally there are eight sensory neurons in nematodes, says White. You can take away seven of the eight prior to sexual maturation, and as long as there is one left, he can still be sexually attracted. Why would an organism that has only 383 nerve cells use eight of them for sexual attraction" It must be that the behavior is very
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Contact: Lee Siegel leesiegel@ucomm.utah.edu 801-581-8993 University of Utah Source:Eurekalert

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