Sex differences are obvious in the vinegar fly Drosophila melanogaster as are in humans. Females and males have distinct reproductive organs internally as well as externally, and the body color patterns are distinctly different, for example. In addition, they are different in behavior, which is most evident in the process of mating. The sex difference in behavior must derive from a sex difference in the neural circuitry. Indeed, the research group headed by Prof. Daisuke Yamamoto, Tohoku University Graduate School of Life Sciences, has demonstrated that certain neurons in the fly brain show prominent sexual differences in their structure between the sexes and the fruitless gene is the key factor that generates these differences. Now the Yamamoto group discovered that when the fruitless gene activity is diminished by genetic manipulations, single neurons in the male brain transform their structure, one-by-one, into the female-typical shape; if fruitless gene functions are completely lost, the male brain bears only female-typical neurons. Thus at the single cell level, this sex switch operates in an all-or-none manner. The Yamamoto group further showed that the Fruitless protein produced by the fruitless gene recruits several proteins that alter chromatin states, the higher structures of chromosomes. They conclude that tightening of the chromosome structure restricts read-out of genetic information, resulting in male-type development of neurons whereas loosening facilitates genetic decoding, leading to female-type development of neurons.

 The research outlined above has appeared in Cell, a scientific journal published in USA. The title of the paper is "Fruitless recruits two antagonistic chromatin factors to establish single-neuron sexual dimorphism".

More information (Japanese)

[Contact]

Professor Daisuke Yamamoto

Graduate School of Life Sciences, Tohoku University

TEL: +81-22-217-6218

E-mail: daichan*m.tohoku.ac.jp (Replace * with @)