Cellular and behavioral functions of fruitless isoforms in Drosophila courtship.
BACKGROUND
Male-specific products of the fruitless (fru) gene control the development and function of neuronal circuits that underlie male-specific behaviors in Drosophila, including courtship. Alternative splicing generates at least three distinct Fru isoforms, each containing a different zinc-finger domain. Here, we examine the expression and function of each of these isoforms.


RESULTS
We show that most fru(+) cells express all three isoforms, yet each isoform has a distinct function in the elaboration of sexually dimorphic circuitry and behavior. The strongest impairment in courtship behavior is observed in fru(C) mutants, which fail to copulate, lack sine song, and do not generate courtship song in the absence of visual stimuli. Cellular dimorphisms in the fru circuit are dependent on Fru(C) rather than other single Fru isoforms. Removal of Fru(C) from the neuronal classes vAB3 or aSP4 leads to cell-autonomous feminization of arborizations and loss of courtship in the dark.


CONCLUSIONS
These data map specific aspects of courtship behavior to the level of single fru isoforms and fru(+) cell types-an important step toward elucidating the chain of causality from gene to circuit to behavior.
Research Institute of Molecular Pathology (IMP), Dr. Bohr-Gasse 7, 1030 Vienna, Austria. Electronic address: avp@mb.au.dk.
Anne C
AC
von Philipsborn
Research Institute of Molecular Pathology (IMP), Dr. Bohr-Gasse 7, 1030 Vienna, Austria.
Sabrina
S
Jörchel
Research Institute of Molecular Pathology (IMP), Dr. Bohr-Gasse 7, 1030 Vienna, Austria.
Laszlo
L
Tirian
Research Institute of Molecular Pathology (IMP), Dr. Bohr-Gasse 7, 1030 Vienna, Austria.
Ebru
E
Demir
Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
Tomoko
T
Morita
Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
David L
DL
Stern
Research Institute of Molecular Pathology (IMP), Dr. Bohr-Gasse 7, 1030 Vienna, Austria; Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA. Electronic address: dicksonb@janelia.hhmi.org.
Barry J
BJ
Dickson
D000818:Animals; D003380:Courtship; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D055785:Gene Knockdown Techniques; D007150:Immunohistochemistry; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics*
D029721:Drosophila Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D014157:Transcription Factors; C103226:fru protein, Drosophila