The Journal of Neuroscience, April 1, 2003, 23(7):2696
Caenorhabditis elegans UNC-103 ERG-Like Potassium
Channel Regulates Contractile Behaviors of Sex Muscles in Males before
and during Mating
L. Rene
Garcia1 and
Paul W.
Sternberg2
1 Department of Biology, Texas A&M University, College
Station, Texas 77843-3258, and 2 Howard Hughes Medical
Institute and Division of Biology, California Institute of Technology,
Pasadena, California 91125
During mating behavior the Caenorhabditis elegans
male must regulate periodic and prolonged protractor muscle
contractions to insert his copulatory spicules into his mate. The
protractors undergo periodic contractions to allow the spicules to
reattempt insertion if a previous thrust failed to breach the vulva.
When the spicule tips penetrate the vulva, the protractors undergo prolonged contraction to keep the spicules inside the hermaphrodite until sperm transfer is complete. To understand how these contractions are regulated, we isolated EMS-induced mutations that cause males to
execute prolonged contraction inappropriately. Loss-of-function mutations in the unc-103 ERG-like K+
channel gene cause the protractor muscles to contract in the absence of
mating stimulation. unc-103-induced spicule protraction can be suppressed by killing the SPC motor neurons and the anal depressor muscle: cells that directly contact the protractors. Also,
reduction in acetylcholine suppresses unc-103-induced
protraction, suggesting that UNC-103 keeps cholinergic neurons from
stimulating the protractors before mating behavior. UNC-103 also
regulates the timing of spicule protraction during mating behavior.
unc-103 males that do not display mating-independent
spicule protraction show abnormal spicule insertion behavior during
sex. In contrast to wild-type males, unc-103 mutants
execute prolonged contractions spontaneously within sequences of
periodic protractor contractions. The premature prolonged contractions
cause the spicules to extend from the male tail before the spicule tips
penetrate the vulva. These observations demonstrate that
unc-103 controls various aspects of spicule function.
Key words:
Caenorhabditis elegans; mating
behavior; unc-103; ERG; K+
channel; L-type voltage-gated calcium channels
Copyright © 2003 Society for Neuroscience 0270-6474/03/2372696-10$05.00/0
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