CIRCADIAN REGULATION OF FOS-LIKE EXPRESSION IN THE BRAIN OF THE BLOW FLY CALLIPHORA-VICINA

Expression of Fos-like immunoreactivity (FOS-lir) was examined in the brains of the blow fly Calliphora vicina for evidence of circadian reg ulation by photic stimuli. Fos-lir in various parts of the brain was i nvestigated as a function of light and time of day. Immunohistochemist ry demonstrated that photic stimuli have an inductive effect on c-fos expression in the various parts of the brain, but only in the neurons of the pars intercerebralis did the clear photic induction of c-fos ex pression occur at times when light was capable of phase shifting circa dian locomotor activity rhythms. This suggests that the c-fos gene may play a role in the photic pathway for circadian entrainment and that these neurons may be involved in the transduction of photic signals. W hether changes in c-Jos expression are essential components of this pa thway remains to be determined. Copyright (C) 1996 Elsevier Science In c.