Few ideas are as foundational to biology as that of evolution by natural selection. Launched by Charles Darwin and his magnum opus On the Origin of Species by Means of Natural Selection, the study of evolution continues to be pivotal to research throughout fields of biological study today. Fitness, the likelihood of an animal’s genes being passed on to the next generation via reproduction, is central to the theory of evolution, and few biological behaviors are as essential a component of an animal’s fitness as courtship behavior.

Dr. Kenta Asahina, Assistant Professor and The Helen McLoraine Development Chair in Neurobiology at the Salk Institute, and his lab study the neurobiology of courtship behavior in the fruit fly Drosophila melanogaster. This study of courtship behavior is a key component of the overarching research mission in the lab to understand the genetic and neuronal basis of internal states that ultimately drive behavior. The lab leverages many of the latest genetic tools in neuroscience, such as CRISPR/Cas9 genome editing, 2-photon functional imaging, and optogenetics to pursue this research mission.

In a paper published this year in eLife, Dr. Asahina and his lab utilize optogenetics to selectively stimulate a subpopulation of sexually dimorphic neurons that co-express the sex-determining genes doublesex (dsx) and fruitless (fru) in male Drosophila. As shown in the figure below, they were able to show that optogenetic stimulation of these dsx– and fru-expressing neurons resulted in increased courtship behavior (time orienting and wing extension) and decreased aggressive behavior (lunges) when the “target” fly was female as opposed to male. These results demonstrate that dsx– and fru-expressing neurons determine behavioral output towards a social partner in an evolutionary vital context that is specific to the sex of that social partner. The researchers go on to show that dsx controls a male-specific courtship execution mechanism, while fru is necessary for enhancement of courtship towards females and aggressive behavior toward fellow males.

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To learn more about Dr. Asahina’s recent research, please tune in to his talk “Playing game in the mind of the fly” this upcoming Tuesday, June 9 at 4:00 p.m. on Zoom (https://uchealth.zoom.us/j/501283195).

Written by Andrew Bender, a 1st Year in the UCSD Neurosciences Graduate Program.

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