Wang ZhePeng, Liu RuiFang, Wang AnRu, Du LiLi, Deng XueMei
College of Animal Science and Technology, China Agricultural University, Beijing, 100094, China.
Sci China C Life Sci. 2008 Oct;51(10):885-93. doi: 10.1007/s11427-008-0085-5. Epub 2008 Sep 26.
Melanin plays an important role in protecting organisms from ultraviolet radiation (UVR). Therefore, it is possible that differently colored strains can show different sensitivities to UVR. In the present work, life span, fertility and courtship behavior of wild type (w), ebony (e) and yellow (y) strains of Drosophila melanogaster were studied to evaluate their sensitivity to ultraviolet (UV). Because a range of phototoxic effects of UVR are mediated through generation of free radicals, levels of free radicals, lipid peroxide (malondialdehyde, MDA) and superoxide dismutase (SOD) activity of three strains were examined to indicate their antioxidant defending ability and oxidative status. It was shown that w always had the highest lifespan and fertility not only in the control but also in UV-exposed groups. Moreover, lifespan and fertility of e were significantly higher (P<0.0001) than those of y in the UV-exposed groups, but not for the control. On the other hand, UV exposure had an adverse effect on courtship of flies. Stronger electron paramagnetic resonance (EPR) signals could be detected in w, e and y exposed to 5 min UV. And there were more significant changes of EPR signals in y than in w and e. UVR had no significant (P=0.1782) effect on the SOD activities. After pooling data from the control and UV-exposed groups, we found that w had a significantly (P<0.05) higher level of SOD activity, but e and y were nearly at the same levels (P>0.05). MDA levels were increased in the UV dose-dependent manner (P=0.0495). In conclusion, our results suggested that UVR can decrease life span and fertility of flies and do harm to courtship, which may be due to oxidative damage to flies tissues (e.g. central nervous system) induced by free radicals. w had the highest tolerance to UVR, which may be ascribed to its advantage of survival under the natural condition and at high level of SOD activity. Then differences of pigment between e and y in absorbing UV, shielding against UV and scavenging free radicals produced by UVR should be responsible for their different sensitivity to UVR.
黑色素在保护生物体免受紫外线辐射（UVR）方面发挥着重要作用。因此，不同颜色的品系可能对UVR表现出不同的敏感性。在本研究中，对黑腹果蝇的野生型（w）、乌木色（e）和黄色（y）品系的寿命、繁殖力和求偶行为进行了研究，以评估它们对紫外线（UV）的敏感性。由于UVR的一系列光毒性作用是通过自由基的产生介导的，因此检测了这三个品系的自由基水平、脂质过氧化物（丙二醛，MDA）和超氧化物歧化酶（SOD）活性，以表明它们的抗氧化防御能力和氧化状态。结果表明，无论是在对照组还是紫外线照射组中，w的寿命和繁殖力总是最高的。此外，在紫外线照射组中，e的寿命和繁殖力显著高于y（P<0.0001），但在对照组中并非如此。另一方面，紫外线照射对果蝇的求偶行为有不利影响。在暴露于5分钟紫外线的w、e和y中可以检测到更强的电子顺磁共振（EPR）信号。并且y中EPR信号的变化比w和e中更显著。UVR对SOD活性没有显著影响（P=0.1782）。将对照组和紫外线照射组的数据汇总后，我们发现w的SOD活性水平显著更高（P<0.05），但e和y的水平几乎相同（P>0.05）。MDA水平以紫外线剂量依赖性方式增加（P=0.0495）。总之，我们的结果表明，UVR会降低果蝇的寿命和繁殖力，并对求偶行为造成损害，这可能是由于自由基对果蝇组织（如中枢神经系统）的氧化损伤所致。w对UVR的耐受性最高，这可能归因于其在自然条件下的生存优势和高水平的SOD活性。然后，e和y在吸收紫外线、屏蔽紫外线和清除UVR产生的自由基方面的色素差异应是它们对UVR不同敏感性的原因。
