Contribution of Social Influences through Superposition of Visual and Olfactory Inputs to Circadian Re-entrainment.

Circadian patterns of locomotor activity are influenced by social interactions. Studies on insects highlight the importance of volatile odors and the olfactory system. Wild-type Drosophila exhibit immediate re-entrainment to new light:dark (LD) cycles, whereas cry and jet mutants show deficits in re-entrainability. We found that both male mutants re-entrained faster to phase-shifted LD cycles when social interactions with WT female flies were promoted than the isolated males. In addition, we found that accelerated re-entrainment mediated by social interactions depended on both visual and olfactory cues, and the effect of both cues presented jointly was nearly identical to the sum of the effects of the two cues presented separately. Moreover, we found that re-entrainment deficits in period (per) expression-oscillation in jet mutants were partially restored by promoting social interactions. Our results demonstrated that, in addition to olfaction, social interactions through the visual system also play important roles in clock entrainment.