Ultraviolet (280–400 nm)–induced DNA Damage in the Eggs and Larvae of Calanus finmarchicus G. (Copepoda) and Atlantic Cod (Gadus morhua)¶

Abstract

In previous work, we evaluated the effects of ultraviolet (UV = 280-400 nm) radiation on the early life stages of a planktonic Calanoid copepod (Calanus finmarchicus Gunnerus) and of Atlantic cod (Gadus morhua). Both are key species in North Atlantic food webs. To further describe the potential impacts of UV exposure on the early life stages of these two species, we measured the wavelength-specific DNA damage (cyclobutane pyrimidine dimer [CPD] formation per megabase of DNA) induced under controlled experimental exposure to UV radiation. UV-induced DNA damage in C. finmarchicus and cod eggs was highest in the UV-B exposure treatments. Under the same spectral exposures, CPD loads in C. finmarchicus eggs were higher than those in cod eggs, and for both C. finmarchicus and cod embryos, CPD loads were generally lower in eggs than in larvae. Biological weighting functions (BWF) and exposure response curves that explain most of the variability in CPD production were derived from these data. Comparison of the BWF revealed significant differences in sensitivity to UV-B: C. finmarchicus is more sensitive than cod, and larvae are more sensitive than eggs. This is consistent with the raw CPD values. Shapes of the BWF were similar to each other and to a quantitative action spectrum for damage to T7 bacteriophage DNA that is unshielded by cellular material. The strong similarities in the shapes of the weighting functions are not consistent with photoprotection by UV-absorbing compounds, which would generate features in BWF corresponding to absorption bands. The BWF reported in this study were applied to assess the mortality that would result from accumulation of a given CPD load: for both C. finmarchicus and cod eggs, an increased load of 10 CPD Mb(-1) of DNA due to UV exposure would result in approximately 10% mortality.

UVA-induced photo recovery during early zebrafish embryogenesis

“…It is possible that chemical exposure of embryos early in the cleavage stage may damage the chorion, thus leading to high mortality; while damage to the chorion at later stages would have less effect on embryo survival when its role is less critical. Moreover, when subjected to UV irradiation, the more elastic cleavage stage chorion combined with the fluid-filled perivitelline space may provide embryos with protection from UVB [33]. Our findings are also in agreement with studies of calanoid copepod and Atlantic cod Gadus morhua , in which larvae were found to be more sensitive to UVB than eggs [33].…”

“…Moreover, when subjected to UV irradiation, the more elastic cleavage stage chorion combined with the fluid-filled perivitelline space may provide embryos with protection from UVB [33]. Our findings are also in agreement with studies of calanoid copepod and Atlantic cod Gadus morhua , in which larvae were found to be more sensitive to UVB than eggs [33]. …”

Effect of Sub-Lethal Exposure to Ultraviolet Radiation on the Escape Performance of Atlantic Cod Larvae (Gadus morhua)

“…Alemanni et al [28] exposed juvenile rainbow trout to sub-lethal level of UV-B radiation and observed stressed behavior such as rapid and erratic displacements and an increase in oxygen consumption. UV-B induced DNA damage has been reported in a variety of fish larvae such as Atlantic cod [15], [46], northern anchovy ( Englausis mordax ) [47], icefish ( Cephalus aceratus ) [16] and Japanese medaka ( Oryzias latipes ) [48]. Moreover, ATP is required for the performance of the first step of excision repair of DNA damage [49], resulting in energy loss to the recovery process (energy that could otherwise be used for other metabolic processes).…”

“…Fish larvae are also often present in the surface waters (see [14]). A large number of studies have reported deleterious effects of UV-B on fish eggs and larvae such as DNA damage [15], [16], increased mortality [12], [13], [17]–[19] malformation [20], lesion of skins, eyes and brains [12], [21], [22], retarded growth [12], [23], and immune depression [23]–[26]. The indirect effects of UV radiation on aquatic ecosystems have recently been receiving more attention (e.g.…”

Induction of cytochrome P450 1 genes and stress response genes in developing zebrafish exposed to ultraviolet radiation

“…The most pronounced effect of prolonged exposure to UV in humans is induction and development of skin cancer (Brash 1997; Brash et al 1991; Setlow 1974). In aquatic organisms the effects of UV radiation include impairment of larval development in copepods and fish (Browman et al 2003; Hakkinen et al 2004; Hunter et al 1979), lesions to the brain and retina of developing fish (Hunter et al 1979), oxidative stress in Daphnia and in adult zebrafish (Vega and Pizarro 2000), and other effects as reviewed elsewhere (Dahms and Lee 2009; Häder et al 2007; Zagarese and Williamson 2001). …”