CIRCADIAN CLOCK-CONTROLLED GENES ISOLATED FROM NEUROSPORA-CRASSA ARE LATE NIGHT-SPECIFIC TO EARLY MORNING-SPECIFIC

An endogenous circadian biological clock controls the temporal aspects of life in most organisms, including rhythmic control of genes involv ed in clock output pathways. In the fungus Neurospora crassa, one path way known to be under control of the clock is asexual spore (conidia) development. To understand more fully the processes that are regulated by the N. crassa circadian clock, systematic screens were carried out for genes that oscillate at the transcriptional level. Time-of-day-sp ecific cDNA libraries were generated and used in differential screens to identify six new clock-controlled genes (ccgs). Transcripts specifi c for each of the ccgs preferentially accumulate during the late night to early morning, although they vary with respect to steady-state mRN A levels and amplitude of the rhythm. Sequencing of the ends of the ne w ccg cDNAs revealed that ccg-12 is identical to N. crassa cmt encodin g copper metallothionein, providing the suggestion that not all clock- regulated genes in N. crassa are specifically involved in the developm ent of conidia, This was supported by finding that half of the new ccg s, including cmt (ccg-12), are not transcriptionally induced by develo pmental or light signals. These data suggest a major role for the cloc k in the regulation of biological processes distinct from development.