Ultraviolet absorbing compounds provide a rapid response mechanism for UV protection in some reef fish

• Published in: Journal of photochemistry and photobiology. B, Biology Vol. 160; pp. 400 - 407
• Main Authors: Braun, C., Reef, R., Siebeck, U.E.
• Format: Journal Article
• Language: English
• Published: Switzerland Elsevier B.V 01-07-2016
• Subjects: Amino Acids - chemistry; Amino Acids - metabolism; Animals; Cyclohexanols - chemistry; Cyclohexanols - metabolism; DNA damage; DNA Damage - radiation effects; Fishes - metabolism; Mucus - chemistry; Mucus - metabolism; Mycosporine-like amino acids; Pomacentrus amboinensis; Reef fish; Sunscreening Agents - chemistry; Sunscreening Agents - metabolism; Sunscreens; Thalassoma lunare; Ultraviolet absorbing compounds; Ultraviolet Rays; UV radiation; UV radiation; Mycosporine-like amino acids; Sunscreens; Ultraviolet absorbing compounds; DNA damage; Pomacentrus amboinensis; Reef fish
• ISSN: 1011-1344; 1873-2682
• DOI: 10.1016/j.jphotobiol.2016.04.020

The external mucus surface of reef fish contains ultraviolet absorbing compounds (UVAC), most prominently Mycosporine-like Amino Acids (MAAs). MAAs in the external mucus of reef fish are thought to act as sunscreens by preventing the damaging effects of ultraviolet radiation (UVR), however, direct evidence for their protective role has been missing. We tested the protective function of UVAC's by exposing fish with naturally low, Pomacentrus amboinensis, and high, Thalassoma lunare, mucus absorption properties to a high dose of UVR (UVB: 13.4W∗m−2, UVA: 6.1W∗m−2) and measuring the resulting DNA damage in the form of cyclobutane pyrimidine dimers (CPDs). For both species, the amount of UV induced DNA damage sustained following the exposure to a 1h pulse of high UVR was negatively correlated with mucus absorbance, a proxy for MAA concentration. Furthermore, a rapid and significant increase in UVAC concentration was observed in P. amboinensis following UV exposure, directly after capture and after ten days in captivity. No such increase was observed in T. lunare, which maintained relatively high levels of UV absorbance at all times. P. amboinensis, in contrast to T. lunare, uses UV communication and thus must maintain UV transparent mucus to be able to display its UV patterns. The ability to rapidly alter the transparency of mucus could be an important adaptation in the trade off between protection from harmful UVR and UV communication.
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•Ultraviolet absorbing compounds (UVACs) and MAAs have been dubbed nature's sunscreens.•The efficiency of MAAs to protect against UV induced DNA damage is yet unknown.•We induced DNA damage in reef fish with variable UVACs in their external mucus.•Fish with more sunscreens in their mucus had less DNA damage in skin samples.•An increase in mucus absorption when exposed to UV radiation was observed in one species.