Gene Expression Associated with Early and Late Chronotypes in Drosophila melanogaster

Abstract

The circadian clock provides the temporal framework for rhythmic behavioral and metabolic functions. In the modern era of industrialization, work, and social pressures, clock function is jeopardized, and can result in adverse and chronic effects on health. Understanding circadian clock function, particularly individual variation in diurnal phase preference (chronotype), and the molecular mechanisms underlying such chronotypes may lead to interventions that could abrogate clock dysfunction and improve human (and animal) health and welfare. Our preliminary studies suggested that fruit-flies, like humans, can be classified as early rising “larks” or late rising “owls,” providing a convenient model system for these types of studies. We have identified strains of flies showing increased preference for morning emergence (Early or E) from the pupal case, or more pronounced preference for evening emergence (Late or L). We have sampled pupae the day before eclosion (fourth day after pupariation) at 4 h intervals in the E and L strains, and examined differences in gene expression by RNA-seq. We have identified differentially expressed transcripts between the E and L strains, which provide candidate genes for subsequent studies of Drosophila chronotypes and their human orthologs.

The genetic basis of diurnal preference in Drosophila melanogaster

“…Notably, a comparison of gene expression between diurnal and nocturnal flies highlighted just a single core clock gene (pdp1). This finding is reminiscent of the results of our previous study in flies [37], where transcriptional differences between early and late chronotypes were present in genes up-and downstream of the clock but not in the clock itself. The phase conservation of core clock genes in diurnal and nocturnal animals has also been documented in mammals [38][39][40].…”

Association between bedtime and the prevalence of newly diagnosed non‐alcoholic fatty liver disease in adults

“…Secondly, there may also be a genetic vulnerability in late sleepers that may predispose them to metabolic dysregulation . An animal study demonstrated that chronotype diversity was largely mediated by genes and molecular processes were entirely different in evening and morning chronotype . Recently, a genome‐wide association study of self‐reported chronotype within the UK Biobank cohort (n = 100 420) found that several novel genetic loci were significantly associated with chronotype …”

Flies as models for circadian clock adaptation to environmental challenges

“…Thus, the observed latitudinal cline in TIM polymorphism appears to be an evolutionary adaptation to the conditions at higher latitudes (Kyriacou, Peixoto, Sandrelli, Costa, & Tauber, ). Polymorphisms appear also present in CRY, but a clear latitudinal cline was so far not observed (Pegoraro et al., ).…”