While the mechanism that breaks left-right (L-R) anatomical asymmetry has been described in C. elegans, we have found that at least one additional mechanism must exist to generate L-R differences in the deployment of alternative cell death pathways in the male tail, male mating behavior and patterning of the male gonad. Upon recognizing a hermaphrodite, males initiate backward locomotion and continuously scan along the hermaphrodite's body. When their tails reach either the head or tail of the hermaphrodite, males turn to maintain contact and then continue backward locomotion on the opposite side of the hermaphrodite. We found that this turning behavior shows a distinct right-handed bias: when individual males were allowed to mate with
lin-2(
e1309) vulvaless hermaphrodites, >70% of the turns when made over the hermaphrodites' body (away from the agar surface) and >55% of turns when made under the hermaphrodites' body (toward the agar surface) are right-handed. To determine whether this bias in turning direction correlated with L-R asymmetry in the male mating structure, which results from stochastic EGL-1-dependent loss of sensory rays, we examined the turning bias in
egl-1(
n1084n3082) mutants. Wild-type males lack rays more frequently on the right and
egl-1 mutant males have no ray loss but still display the right-hand turning bias. To assess whether this L-R behavioral bias is dependent on anatomical asymmetry, we analyzed
gpa-16(
it143) mutants in which the L-R asymmetry of the internal organs is reversed as a result of the reversal in the early embryonic symmetry break. Males with reversed anatomical asymmetry showed a virtually identical right hand bias in turning, demonstrating that an asymmetry-determining system that is independent of the previously described L-R symmetry breaking event must control this behavior. During the characterization of the gonad reversals of males, we also observed a previously unreported temperature sensitive reversal of L-R asymmetry of the male gonads in N2 (Bristol) and a Hawaiian wild isolate. We will describe our recent findings on these novel L-R asymmetries of the C.elegans male anatomy and behavior.