Sexually dimorphic and clock-gene specific effects of artificial light at night on Drosophila behavioral rhythms

Light pollution is a major anthropogenic environmental change and a
significant threat to ecosystems. Among other detrimental effects on
physiology, light at night (LAN) disrupts circadian rhythms in a wide
range of species. However, the underlying neuronal and genetic mechanisms
remain poorly understood. Here, we show that the loss of the circadian
clock gene period (per) exacerbates the LAN-induced shift toward nocturnal
behaviour, with a more pronounced effect on males. In contrast, the loss
of cycle has no such effect on males or females; cyc null mutants are
nocturnal under standard light‒dark cycles, and their activity and sleep
profiles are minimally or not affected by LAN exposure. CRISPR-Cas9
knockout of per in most clock neurons resembles the null mutant phenotype.
Our results show that mutations in components of the positive and negative
limbs of the circadian clock result in distinct responses to nocturnal
light and highlight the role of genetic factors in modulating behavioural
plasticity in response to environmental perturbations.