The interplay of light and the circadian clock. Independent dual regulation of clock-controlled gene ccg-2(eas).
Ambient light is the major agent mediating entrainment of circadian rhythms and is also a major factor influencing development and morphogenesis. We show that in Neurospora crassa the expression of clock-controlled gene 2 (ccg-2), a gene under the control of the circadian clock and allelic to the developmental gene easy wettable (eas), is regulated by light in wild-type strains. Light elicits a direct and important physiological effect on ccg-2(eas) expression as demonstrated using several mutant Neurospora strains. In white collar mutants (wc-1 and wc-2) that are "blind" to blue light, ccg-2(eas) mRNA shows no variation following illumination with saturating light. By contrast, ccg-2(eas) mRNA is photoinduced in clock-null strains such as frequency (bd;frq). The results in the clock mutants show that an intact circadian oscillator is not required for light induction of ccg-2(eas). Thus, ccg-2(eas) is subject to a dual regulation that involves separable regulation by light and circadian rhythm.
Arpaia
G
G
Dipartimento di Biopatologia Umana, Università di Roma La Sapienza, Italy.
Loros
J J
JJ
Dunlap
J C
JC
Morelli
G
G
Macino
G
G
D000483:Alleles; D002940:Circadian Rhythm / Q000235:genetics*; D005800:Genes, Fungal; D005838:Genotype; D008027:Light; D009492:Neurospora crassa / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis
D012333:RNA, Messenger