Transcriptome-wide deregulation of gene expression in zebrafish exposed to artificial light at night

Jun 18, 2025Environmental pollution (Barking, Essex : 1987)

Widespread changes in gene activity in zebrafish exposed to artificial light at night

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Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

A one-month exposure to artificial light at night (ALAN) altered the expression of several genes in zebrafish, impacting their biological functions.

The expression of circadian clock genes varied significantly in zebrafish exposed to ALAN.
Genes related to immunity, stress response, sensory stimuli, energy production, motor activity, and reproduction also showed altered expression levels.
The highest number of differentially expressed genes was observed during early morning hours and at night.
Changes in gene expression occurred both during direct exposure to ALAN and under natural light conditions.
These findings may indicate broader biological impacts of ALAN on aquatic species than previously recognized.

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Urbanization and human activities are increasing global levels of artificial light at night (ALAN). Several studies have shown that ALAN negatively impacts animals, altering their perception, physiology, and behaviour, eventually leading to reduced fitness. ALAN also disrupts biological rhythms, affecting animals' ability to synchronize with natural cycles. There still is a critical lack of knowledge on ALAN's effects on freshwater ecosystems, which are highly threatened biodiversity hotspots. Our study aimed to understand the molecular effect of prolonged ALAN exposure in the zebrafish, a model species in this field. Using high-throughput RNA sequencing, we investigated the transcriptome-wide gene expression responses in whole brains of ALAN-exposed zebrafish. Samples were collected at four different timepoints along the day, two at daytime and two at nighttime, to identify daily changes in gene expression and metabolic pathways. A one month exposure to ALAN varied the expression of several genes and metabolic pathways, both at night, when zebrafish were directly exposed to artificial light, and during the day, at natural light conditions. The highest number of differentially expressed genes were found at the early hours of the day and at night. Overall, circadian clock genes and those related to immunity, stress response, responses to sensory stimuli, energy production, motor activity, and reproductive processes changed in expression levels. These results provide new insights into the mechanisms through which ALAN affects animal biology, suggesting broader impacts than previously recognised. To safeguard aquatic ecosystems and their biodiversity, it is paramount to mitigate light pollution.

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Transcriptome-wide deregulation of gene expression in zebrafish exposed to artificial light at night

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