Transcriptional response of circadian clock genes to an 'artificial light at night' pulse in the cricket Gryllus bimaculatus
Light is the major signal entraining the circadian clock that regulates physiological and behavioral rhythms in most organisms, including insects. Artificial Light at Night (ALAN) disrupts the natural light-dark cycle and negatively impacts animals at various levels. We simulated ALAN using dim light stimuli and tested their impact on gene expression in the cricket Gryllus bimaculatus, a model of insect physiology and chronobiology. At night, adult LD crickets were exposed for 30 minutes to a light pulse of 2-40 lx. The relative expression of five circadian clock associated genes was compared using qPCR. A dim ALAN pulse elicited tissue-dependent differential expression in some of these genes. The strongest effect was observed in the brain and in the optic lobe, the crickets circadian pacemaker. Expression of opsin-Long Wave (opLW) was upregulated, as well as cryptochrome1-2 (cry), and period (per). Our findings demonstrate that even a dim ALAN exposure may affect insects at the molecular level, underscoring the detrimental impact of ALAN on the circadian clock system.