lnterspecific Variation in UV Defense Mechanisms Among Temperate Freshwater Fishes

Abstract

An important step in predicting the effects of future increases in UV radiation (UVR) is to evaluate the mechanisms that organisms use to prevent and repair DNA damage and determine how those mechanisms influence UVR sensitivity. Damage is prevented to varying degrees through photoprotection and repaired via two main pathways: nucleotide excision repair and photoenzymatic repair. At present, little is known about the generality or similarity of these defenses among temperate freshwater fishes. We used laboratory experiments to compare UVR defense mechanisms among five freshwater fish species representing four families and three orders. Purified DNA, freeze-killed larvae and live larvae were exposed to UVB radiation for 12 h in the presence or absence of photorepair radiation. After exposure, we quantified frequencies of cyclobutane pyrimidine dimers in each exposure treatment. All five species used photoprotection and proportional decreases in dimer frequency were similar for all species. Evidence of excision repair was also found for all species but proportional decreases in photoproduct frequencies varied among species. Finally, evidence of photoenzymatic repair was found for only two of the five species.

Differential tolerance of native and nonnative fish exposed to ultraviolet radiation and fluoranthene in Lake Tahoe (California/Nevada), USA

“…Mechanisms of protection against the deleterious effects of UVR radiation vary among freshwater fish, both in type and intensity [28]. These results indicate the native redside is not only more suited for the natural pressures of the Lake's habitat (UVR), but may also tolerate a certain amount of anthropogenic pressure (PAHs).…”

Additive effects of enhanced ambient ultraviolet B radiation and increased temperature on immune function, growth and physiological condition of juvenile (parr) Atlantic Salmon, Salmo salar

“…Higher mortality in freshwater crustaceans that do not have effective photo-enzymatic repair mechanisms has been observed when they were exposed to UV radiation coupled with increased temperature [18]. Of five fish species studied three species, including salmonids Brook Trout (Salvelinus fontinalis) and Rainbow Trout (Oncorhynchus mykiss), were found to lack photo-enzymatic repair [19]. Thus, there exists the potential for effects of UVB and temperature on health measures in fish.…”

UVA-induced photo recovery during early zebrafish embryogenesis

“…Although there are previous studies of photoreactivation in aquatic organisms, DNA photorepair is less well studied in freshwater animals [10]. Zebrafish ( Danio rerio ) are freshwater fish whose small size, fecundity, embryonic transparency, and rapid development have led to their selection as a popular model vertebrate.…”