Environmental Radiation Effects Research Group, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
Environ Pollut. 2010 May;158(5):1689-95. doi: 10.1016/j.envpol.2009.11.022. Epub 2009 Dec 22.
The gene expression of environmental organisms is useful as a biomarker of environmental pollution. One of its advantages is high sensitivity. We identified the cDNA of a novel cadmium-responsive gene in the soil collembolan Folsomia candida. The deduced protein, designated "metallothionein-like motif containing protein" (MTC), was cysteine-rich and contained a metallothionein-like motif with similarity to metallothionein, but had a much longer sequence than metallothionein and contained repeated sequences of amino acids. Expression of MTC mRNA was sensitively induced by cadmium exposure at 0.3 mg/kg of dry food, a concentration at which toxic effects are not observed, but expression was not affected by gamma-ray exposure (an inducer of oxidative stress). These findings suggest that MTC is involved in cadmium-binding processes rather than in oxidative-stress responses. In conclusion, we suggest that gene expression of MTC may be a candidate biomarker for detecting low levels of cadmium contamination in soil.
环境生物的基因表达可用作环境污染的生物标志物。其优点之一是灵敏度高。我们在土壤跳虫 Folsomia candida 中鉴定出一种新型镉响应基因的 cDNA。推断的蛋白质被命名为“含金属硫蛋白样基序的蛋白”（MTC），富含半胱氨酸，含有与金属硫蛋白相似的金属硫蛋白样基序，但序列比金属硫蛋白长得多，并且含有氨基酸的重复序列。在 0.3mg/kg 的干食物浓度下，MTC mRNA 的表达被镉暴露敏感诱导，该浓度下未观察到毒性作用，但表达不受γ射线暴露（氧化应激诱导剂）的影响。这些发现表明，MTC 参与镉结合过程而不是氧化应激反应。总之，我们认为 MTC 的基因表达可能是检测土壤中低水平镉污染的候选生物标志物。
