Differential Gene Expression in the Skin of Xiphophorus Maculatus Jp 163 B in Response to Full Spectrum (10,000 K) Fluorescent Light
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Over the past decade physiological and psychological effects of artificial fluorescent lighting on humans has been shown to be significant and quantifiable. Both the amount and composition of lighting are important parameters associated with human and animal health. Published reports suggest human physiological responses to “full spectrum” vs. “cool white” lamps include differences in oxygen intake, heart rate, absorption of vitamins and minerals, etc. Despite many behavioral and physiological studies indicating artificial light sources may be important to health there exists a paucity of data regarding specific molecular genetic responses occurring in tissues of intact animals upon exposure to varying types of artificial lighting. Tropical fishes, such as Xiphophorus, may be expected to represent vertebrate experimental models that are both very sensitive and responsive to varying light conditions. In the wild, fishes utilize light conditions for warmth, predation, predator avoidance, and to coordinate breeding cycles. Recently, our laboratory has been employing Xiphophorus fishes and RNA-Seq methods to investigate global changes in skin gene expression after exposure of the intact animal to various types of lighting and wavelengths. This was initiated as a means to identify genetic patterns that may hallmark a predisposition to melanoma induction, but comparison of data indicated fluorescent light exposure resulted in a molecular genetic response nearly as great in amplitude as observed for ultraviolet B (UVB) exposure. Given the current widespread use of fluorescent lighting in human and animal facilities, we sought to examine the extent other light sources may influence molecular genetic regulation in fish skin. Herein, we present results showing exposure to full spectrum fluorescent light (10,000 K) affects different biological processes in Xiphophorus skin. Biological replicates of Xiphophorus males Jp 163 B were exposed to varying doses of 10,000 K light. Functional pathway analyses revealed an overall shared suppression of expressed genes associated with cell cycle phase transition, mitotic spindle assembly, chromosome segregation and DNA replication, while shared genes increased in expression were associated with the circadian-rhythmic process and cell structure. Unique responses were observed at individual exposures, the majority of which were represented by genes exhibiting an increase in expression. These unique responses were associated with lipid and cholesterol catabolism, phosphorylation and epidermis structure. Our results suggest exposure to full spectrum fluorescent light largely results in stalling of mitotic progression, induces catabolic processes and implicates inflammatory response in skin. Overall, these results characterize the genetic responses induced by 10,000 K light in X. maculatus Jp 163 B skin.