“It is difficult to say ostensibly ‘I love you.’ I am a bit embarrassed, but let’s try a wink.”
Courtship behavior is important for any animals to produce offspring. Professor Daisuke Yamamoto, Assistant Professor Masayuki Koganezawa at Graduate School of Life Sciences, Tohoku University and Assistant Professor Takashi Matsuo at Tokyo Metropolitan University have discovered that a male Drosophila fruitfly gets to know how to pose for courtship by gustation. Male Drosophila usually vibrates a single wing during courtship to generate “love songs”. When gustatory nerve cells are paralyzed with a toxin or impaired by some other means, the awkward male moves both wings, and his courtship does not go well. This is just like a poor human male who wanted to wink but unintentionally closed both eyes in action. This epoch-making study explains unknown instinct’s secret by manipulating two kinds of neurons and two defined genes that critically mediate sexual communication. The research results have been published online in Current Biology, a UK science journal, on December 24, 2009. The paper’s title is “The shaping of male courtship posture by lateralized gustatory inputs to male-specific interneurons”.

 Courtship behavior is pivotal for successful reproduction. Recently, many research results have been produced including the discovery of genes that switch the gender-specific behavioral patterns of the fruitfly courtship ritual. However, little is known about the factors and mechanisms that instruct each step of courtship behavior.

 Courtship by fruitfly males is known for unilateral wing vibration to generate “love songs.” They have gustatory cells in a foreleg besides the mouth. Before playing love songs, males touch the female abdomen with a foreleg to taste body surface waxes that work as pheromones. By sensing these pheromones, males make sure that the courtship target in question is indeed a female of the same spices.

 The research group has successfully specified Gr32a, a receptor protein to sense a component of the pheromones. The group also has conducted experiments to inhibit the gustatory nerve cell function by gene engineering. The result shows that the information received as the pheromone is transmitted to the terminals of mAL, the brain neurons with sexually dimorphic structures, to control the wing motion. When pheromone receptor cells are inactivated, such males fail to vibrate a single wing but vibrate both wings, making him less successful in copulation.

 The research has been conducted with the aid of a Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science (JSPS) and Tohoku Neuroscience Global COE, Basic and Translational Research Center for Global Brain Science.

[Contact]
Professor Daisuke Yamamoto
Graduate School of Life Sciences, Tohoku University
Tel: +81-22-795-7732
E-mail: daichan@mail.tains.tohoku.ac.jp

[Public Relations]
Associate Professor Fuji Nagami
Tohoku Neuroscience Global COE
Tel: +81-22-717-7908, Fax: +81-22-717-7923
E-mail: f-nagami@mail.tains.tohoku.ac.jp