Induction of Photolyase Activity in Wood Frog (Rana sylvatica) Embryos¶

Abstract

Rising ultraviolet-B (UVB, 280-320 nm) radiation has been proposed as a factor which may explain nonnormal amphibian population declines. Accordingly research has been directed toward estimating the photolyase activity of several amphibian species in order to predict a species' resilience to UV damage. Unfortunately, in spite of published research which demonstrated that the activity of one of the principal photorepair enzymes, photolyase, can be induced, these estimates did not address the potential for in vivo induction by environmental factors present in situ. We show here that wood frog (Rana sylvatica) embryos exposed to periods of ambient solar radiation (1) displayed significantly different photolyase activities from embryos exposed to equivalent periods of dark; and (2) were positively correlated with the UVB fluence received in vivo. Such results suggest that previous conclusions regarding the relationship between photorepair and population decline must be reevaluated. Estimating amphibian photorepair is a complicated process, and caution must be exercised when interpreting such data.

Functional acclimation to solar UV‐B radiation in Gunnera magellanica, a native plant species of southernmost Patagonia

“…1994; Malloy et al . 1997; Smith, Kapron & Berrill 2000). Even under optimal conditions (25 °C, WL + UV‐A), the CPD repair rates displayed by G. magellanica leaves appeared to be modest in comparison with published repair kinetics for other species (Pang & Hays 1991; Quaite et al .…”

“…Although no comparative surveys are available in the case of terrestrial plants, variation appears to exist in DNA repair capacity among animal species that live in contrasting UV environments (Blaustein et al 1994;Malloy et al 1997;Smith, Kapron & Berrill 2000). Even under optimal conditions (25 °C, WL + UV-A), the CPD repair rates displayed by G. magellanica leaves appeared to be modest in comparison with published repair kinetics for other species (Pang & Hays 1991;Quaite et al 1994; Sutherland et al and irradiation (open symbols: WL + UV-A; closed symbols: darkness).…”

Stage-dependent teratogenic and lethal effects exerted by ultraviolet B radiation on Rhinella (Bufo) arenarum embryos

“…The assumption that melanin could have a major role against deleterious effects caused by UVB radiation on R. (Bufo) arenarum embryos is in line with the study reported by Perotti and Diéguez [9] in which the photoprotection against UVB radiation in three amphibian species was associated to the melanin content of the embryo. On the other hand, photolyase, one of the principal photo repair enzymes induced by UVB irradiation and antioxidant molecules such as catalase, superoxide dismutase, and glutathion peroxidase, could also contribute to the protection of UVB‐irradiated embryos [15,32].…”

Expression of the DNA Repair Enzyme, Photolyase, in Developmental Tissues and Larvae, and in Response to Ambient UV‐R in the Antarctic Sea Urchin Sterechinus neumayeri

“…In terms of photolyase expression, the response of organisms to UV‐R exposure and resulting DNA damage is species specific. Whereas photolyase is often constitutively expressed independent of UV‐R exposure (25–27), expression of photolyase in Rana sylvatica embryos has been positively correlated with UVB dose (27), and in Carassius auratus , by exposure to visible light (26). The present study suggests that while there is also constitutive photolyase expression in Sterechinus embryos, expression does vary with depth and UV‐R dose.…”