Innate behaviors offer a unique opportunity to use genetic analysis to dissect and characterize the neural substrates of complex behavioral programs. Courtship in Drosophila melanogaster involves a complex series of stereotyped behaviors that include numerous exchanges of multimodal sensory information over time. Recent work has demonstrated that male-specific expression of Fruitless transcription factors (FruM proteins) is necessary and sufficient to confer the potential for courtship behaviors in D. melanogaster males. During development FruM transcription factors program neurons of the male central and peripheral nervous systems whose function is dedicated to sexual behaviors. This circuitry seems to integrate sensory information to define behavioral states and regulate conserved neural elements for sex-specific behavioral output. The findings that FruM proteins are expressed in only a small portion of the nervous system that is dedicated to sexual behavior, and are necessary and sufficient for nearly all aspects of sexual behavior suggest FruM provides a handle for dissecting the developmental, genetic, molecular, and neuronal bases of male courtship behavior.

Our approach to gaining an understanding of how (1) the potential for a complex behavior is built into the nervous system, and (2) the neurons subserving male courtship behavior function together to insure the ordered manifestation of the events comprising this behavior, is to focus on the groups of neurons in which the FruM proteins are expressed. On-the-one-hand we address how the FruM transcription factors shape the anatomical and molecular characteristics of these neurons. On-the-other–hand we address the roles of individual groups of these neurons in the complex set of behaviors that comprise male courtship.

Central to our approach is the development of fru-based genetic tools that permit the manipulation of FruM-expressing neurons, without affecting other neurons. Such constructs allow visualization of the nuclei of FruM-expressing neurons and their projections, silencing of these neurons, changing the sex of these cells from male to female or from female to male, suppression of FruM synthesis in targeted neurons. Thus we can functionally manipulate a discrete group of FruM neurons and behaviorally assess its effects on the execution of male courtship. We can also use these tools to identify the neuroanatomical and molecular characteristics of neurons that are specified by FruM. These studies will likely provide a model for how the circuitries underlying other innate behaviors are built and function.

Dr. Baker grew up in Chicago and attended Reed college in Portland Oregon. He received his Ph.D. from the Genetics Department at the University of Washington where he did his doctoral work with Dr. Larry Sandler on Drosophila chromosome mechanics. He did postdoctoral work with Dr. James Crow in the Genetics Department at the University of Wisconsin. He held faculty positions at the University of North Carolina, Chapel Hill, and the University of California, San Diego before taking up his current position at Stanford University where he has been for the past 20 years. He is currently the Morris Herzstein Professor of Biology.

For many years now Dr. Baker’s research has focused on the molecular genetic basis for sex determination and differentiation, including dosage compensation in Drosophila. Most recently he has focused his labs interest on the basis for the elaborate innate courtship ritual that proceed mating in Drosophila, and has shown that a set of male-specific proteins encoded by the fruitless gene in Drosophila are both necessary and sufficient to specify the potential for male courtship behavior.

http://www.stanford.edu/dept/biology/faculty.html

WALS.