In a study on fruit flies, daily low-intensity blue-light exposure—similar to that experienced daily by billions of humans in the form of LED lighting and device screens—changed flies at the sub-cellular level, affecting processes related to aging and circadian rhythms.

Xiaoyun Wang and colleagues exposed fruit flies (Drosophila melanogaster) to different durations of daily low-intensity blue light, and then analyzed the consequences to the cellular makeup of the insects, compared to flies raised in darkness.

Blue light’s effects on flies

The authors measured blue light’s effects on N6-Methyladenosine (m6A), an RNA modification that is common across the tree of life and plays a role in a wide range of processes.

The authors found that blue light induced genetic transcriptomic** (m6A epitranscriptomic) and metabolomic reprogramming.

Damage to neuronal function

The RNA profiles of 25-day-old male fly heads exposed to blue light were significantly different from 25-day-old male dark-raised flies’ heads, say the authors, and the types of genes that were up- and down-regulated* suggest that blue light exposure can damage neuronal function.

In comparisons of whole-body transcriptomes (the protein-coding part of an organism’s genome) of RNA molecules that are present in cells, however, age created bigger differences between groups than light exposure, suggesting that eye and brain tissues of Drosophila flies are the major tissues affected by blue light.

Differences in mRNA m6A levels and other m6A-related markers between light- and dark-raised flies also indicate that m6A methylation (which regulates reproductive system development) was involved in the impacts of blue light on Drosophila.

Hazards with blue light

According to the authors, attention should be paid to the potential hazards of cumulative blue light exposure in humans because blue light can influence the circadian rhythm and processes mediated by melanopsin-expressing intrinsically photosensitive retinal ganglion cells.

* The process by which a cell increases and decreases (respectively) the production and quantities of its cellular components, such as RNA and proteins, in response to an external stimulus

** The set of all the ribonucleic acid (RNA) molecules (called “transcripts”) expressed in some given entity, such as a cell, tissue, or organism

Citation: Jia Huang, Fan Zhou, Huanchan Zhou, Xiaoqi Zheng, Zhengyi Huo, Meng Yang, Zihe Xu, Runzhou Liu, Luoluo Wang, Xiaoyun Wang, Systematic assessment of transcriptomic and metabolic reprogramming by blue light exposure coupled with aging, PNAS Nexus, Volume 2, Issue 12, December 2023, pgad390, https://doi.org/10.1093/pnasnexus/pgad390 (open-access)

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