Deconvoluting Wavelengths Leading to Fluorescent Light Induced Inflammation and Cellular Stress in Zebrafish (Danio rerio)

Mikki Boswell,Yuan Lu,Markita Savage,William Boswell,Ronald B Walter

doi:10.1038/s41598-020-59502-5

Abstract

Fluorescent light (FL) has been shown to induce a cellular immune and inflammatory response that is conserved over 450 MY of evolutionary divergence and among vertebrates having drastically different lifestyles such as Mus musculus, Danio rerio, Oryzias latipes and Xiphophorus maculatus. This surprising finding of an inflammation and immune response to FL not only holds for direct light receiving organs (skin) but is also observed within internal organs (brain and liver). Light responsive genetic circuitry initiated by the IL1B regulator induces a highly conserved acute phase response in each organ assessed for all of biological models surveyed to date; however, the specific light wavelengths triggering this response have yet to be determined so investigation of mechanisms and/or light specific molecule(s) leading to this response are difficult to assess. To understand how specific light wavelengths are received in both external and internal organs, zebrafish were exposed to specific 50 nm light wavebands spanning the visible spectrum from 300–600 nm and the genetic responses to each waveband exposure were assessed. Surprisingly, the induced cellular stress response previously observed following FL exposure is not triggered by the lower “damaging” wavelengths of light (UVB and UVA from 300–400 nm) but instead is maximally induced by higher wavelengths ranging from 450–500 nm in skin to 500–600 nm in both brain and liver).

Highlights

(skin) but is observed within internal organs
Both research animals and humans are spending increasing amounts of time indoors and under commonly used fluorescent light bulbs, little is known about potential health and genetic effects due to use of this type of artificial light
The uniform spectral distribution of sunlight may suggest that light responsive genetic circuitry has evolved whereby receipt of each wavelength by the organism triggers different biological cues to produce proper genetic modulation leading to proper adaptive behavior as optimized for the specific environmental niche of each organism

Summary

Introduction

(skin) but is observed within internal organs (brain and liver). Light responsive genetic circuitry initiated by the IL1B regulator induces a highly conserved acute phase response in each organ assessed for all of biological models surveyed to date; the specific light wavelengths triggering this response have yet to be determined so investigation of mechanisms and/or light specific molecule(s) leading to this response are difficult to assess. Regardless, the interesting genetic conservation of response to FL is reported in vertebrates spanning different environmental niches (new world tropical versus old world marsh lands), reproductive mechanism (oviparous versus viviparous), and lifestyle (diurnal versus nocturnal). Platyfish exposed to [510–520] nm light, immediately followed by exposure to [350–360] nm light, displayed the genetic response that mimicked only the [510–520] nm exposure; when the exposure sequence was reversed (i.e., exposure to [350–360] nm light followed by [510–520] nm light) the genetic effect was muted, yet more closely reflected the [510–520] nm exposure results This indicated for the first time that higher, more red shifted wavelengths of light were potentially dominant in their effect on genetic modulation than are lower wavelengths of light

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Discussion

Conclusion