Somatic-cell mutation induced by short exposures to cigarette smoke in urate-null, oxidative stress-sensitive Drosophila
Somatic-cell mutation induced by short exposures to cigarette smoke in urate-null, oxidative stress-sensitive Drosophila
复制标题
尿酸盐缺失、氧化应激敏感的果蝇短时间接触香烟烟雾诱导体细胞突变
作者：
Uchiyama;T.;Koike;R.;Yuma;Y.;Okamoto;K.;Arimoto-Kobayashi;S.;Suzuki;T.;Negishi;T.,
我们之前报道过一种无尿酸的果蝇对香烟烟雾（CS）过敏，我们认为CS诱导果蝇氧化应激是因为尿酸是一种有效的抗氧化剂。虽然接触CS的致癌风险已被广泛认识；关于环境CS，特别是气相CS的体内毒性活性的文献尚无定论。迄今为止，尚未通过野生型果蝇的体细胞突变和重组试验（翼斑试验）检测到暴露于CS导致的果蝇体细胞突变，这是一种广泛使用的果蝇体细胞突变检测方法；此外，基因毒性尚未通过涉及DNA修复缺陷果蝇的DNA修复测试证明。在本研究中，我们使用一种新的果蝇菌株（y v ma- 1; mwh）来检测气相CS诱导的诱变性；这些果蝇由于ma- 1突变而无基因，并且它们是多翼毛（mwh）的杂合，这是一种作为体细胞突变标记的突变。在这个新开发的菌株的试验中，一种产生超氧阴离子的除草剂，百草枯，表现出显著的诱变性；相比之下，百草枯对野生型菌株几乎没有诱变作用。将果蝇幼虫暴露于CS中2、4或6h，然后在25°C的即食培养基中保存至成虫。羽化后，对突变斑（由翅膀上的突变毛组成）进行评分。突变点数量在无尿酸的雌性（ma- 1(−/−)）中呈暴露时间依赖性显著增加，而在阳性的雌性（ma- 1(+/−)）中则没有增加。在这项研究中，我们发现短期暴露于CS在该体内系统中具有诱变性。此外，我们使用荧光探针H2DCFDA获得了CS暴露后幼虫活性氧产生的暗示数据。这些结果表明，尿酸可能抵消氧化损伤，部分负责诱导暴露于CS的果蝇幼虫的体细胞突变。
We previously reported that a urate-null strain of Drosophila is hypersensitive to cigarette smoke (CS), and we suggested that CS induces oxidative stress in Drosophila because uric acid is a potent antioxidant. Although the carcinogenic risk of CS exposure is widely recognized; documentation ofin vivogenotoxic activity of environmental CS, especially gaseous-phase CS, remains inconclusive. To date, somatic-cell mutations in Drosophila resulting from exposure to CS have not been detected via the somatic mutation and recombination test (wing spot test) with wild-type flies, a widely used Drosophila assay for the detection of somatic-cell mutation; moreover, genotoxicity has not been documented via a DNA repair test that involves DNA repair-deficient Drosophila. In this study, we used a new Drosophila strain (y v ma-l; mwh) to examine the mutagenicity induced by gaseous-phase CS; these flies are urate-null due to a mutation inma-l, and they are heterozygous for multiple wing hair (mwh), a mutation that functions as a marker for somatic-cell mutation. In an assay with this newly developed strain, a superoxide anion-producing weed-killer, paraquat, exhibited significant mutagenicity; in contrast, paraquat was hardly mutagenic with a wild-type strain. Drosophila larvae were exposed to CS for 2, 4 or 6h, and then kept at 25°C on instant medium until adulthood. After eclosion, mutant spots, which consisted of mutant hairs on wings, were scored. The number of mutant spots increased significantly in an exposure time-dependent manner in the urate-null females (ma-l(−/−)), but not in the urate-positive females (ma-l(+/−)). In this study, we showed that short-term exposure to CS was mutagenic in thisin vivosystem. In addition, we obtained suggestive data regarding reactive oxygen species production in larva after CS exposure using the fluorescence probe H2DCFDA. These results suggest that oxidative damage, which might be countered by uric acid, was partly responsible for induction of somatic cell mutations in Drosophila larvae exposed to CS.