Data from: A significant component of ageing (DNA damage) is reflected in fading breeding colors: an experimental test using innate antioxidant mimetics in painted dragon lizards

A decade ahead of their time, von Schantz and coworkers united sexual selection and free radical biology by identifying causal links between deep-rooted physiological processes that dictate resistance to toxic waste from oxidative metabolism (reactive oxygen species), and phenotypic traits, such as ornaments. Ten years later, these ideas have still only been tested with indirect estimates of free radical levels (oxidative stress) subsequent to the action of innate and dietary antioxidants. Here we measure net superoxide (a selection pressure for antioxidant production) and experimentally manipulate superoxide antioxidation using a synthetic mimetic of superoxide dismutase, Eukarion 134 (EUK). We then measure the toxic effect of superoxide in terms of DNA erosion and concomitant loss of male breeding coloration in the lizard, Ctenophorus pictus. Control males suffered more DNA damage than EUK-males. Spectroradiometry showed that male coloration is lost in relation to superoxide and covaries with DNA erosion; in control males these variables explained 72 % of color loss, whereas in EUK males, the fading of coloration was unaffected by superoxide and unrelated to DNA damage. Thus, EUK’s powerful antioxidation removes the erosion effect of superoxide on coloration and experimentally verifies the prediction that colors reflect innate capacity for antioxidation.

该研究较其所处时代超前十年，von Schantz及其团队将性选择与自由基生物学相融合，明确了两大要素间的因果关联：一是调控机体抵御氧化代谢（oxidative metabolism）产生的有毒代谢废物——活性氧（Reactive Oxygen Species）能力的深层生理过程，二是诸如装饰性特征之类的表型性状。时隔十年，相关理论仍仅通过间接估算先天与膳食抗氧化剂发挥作用后的自由基水平（氧化应激，oxidative stress）来进行验证。本研究首先检测净超氧化物水平（超氧化物是驱动抗氧化系统产生的选择压力），并利用合成超氧化物歧化酶（superoxide dismutase）模拟物Eukarion 134（简称EUK），对超氧化物的抗氧化能力进行实验操控。随后以蜥蜴（Ctenophorus pictus）为研究对象，以DNA损伤及雄性繁殖色的伴随褪去为指标，评估超氧化物的毒性效应。对照组雄性个体的DNA损伤程度显著高于EUK处理组雄性。光谱辐射测定法（spectroradiometry）结果显示，雄性体色褪去程度与超氧化物水平相关，且与DNA损伤程度共变；对照组雄性的体色褪去程度有72%可由这两个变量解释，而EUK处理组雄性的体色褪色则不受超氧化物影响，且与DNA损伤无关。综上，EUK的强效抗氧化作用消除了超氧化物对体色的损伤效应，实验验证了"体色可反映机体先天抗氧化能力"这一理论预测。