Essig Yona J, Webb Samuel M, Stürzenbaum Stephen R
Analytical and Environmental Sciences Division, Faculty of Life Sciences & Medicine, King's College London, London SE1 9NH, UK.
Medical Research Council-Public Health England (MRC-PHE) Centre for Environment & Health, King's College London, London SE1 9NH, UK.
Int J Mol Sci. 2016 Feb 19;17(2):257. doi: 10.3390/ijms17020257.
Environmental metal pollution is a growing health risk to flora and fauna. It is therefore important to fully elucidate metal detoxification pathways. Phytochelatin synthase (PCS), an enzyme involved in the biosynthesis of phytochelatins (PCs), plays an important role in cadmium detoxification. The PCS and PCs are however not restricted to plants, but are also present in some lower metazoans. The model nematode Caenorhabditis elegans, for example, contains a fully functional phytochelatin synthase and phytochelatin pathway. By means of a transgenic nematode strain expressing a pcs-1 promoter-tagged GFP (pcs-1::GFP) and a pcs-1 specific qPCR assay, further evidence is presented that the expression of the C. elegans phytochelatin synthase gene (pcs-1) is transcriptionally non-responsive to a chronic (48 h) insult of high levels of zinc (500 μM) or acute (3 h) exposures to high levels of cadmium (300 μM). However, the accumulation of cadmium, but not zinc, is dependent on the pcs-1 status of the nematode. Synchrotron based X-ray fluorescence imaging uncovered that the cadmium body burden increased significantly in the pcs-1(tm1748) knockout allele. Taken together, this suggests that whilst the transcription of pcs-1 may not be mediated by an exposure zinc or cadmium, it is nevertheless an integral part of the cadmium detoxification pathway in C. elegans.
环境金属污染对动植物的健康风险日益增加。因此，充分阐明金属解毒途径非常重要。植物螯合素合酶（PCS）是一种参与植物螯合素（PCs）生物合成的酶，在镉解毒中起重要作用。然而，PCS和PCs并不局限于植物，在一些低等后生动物中也存在。例如，模式线虫秀丽隐杆线虫含有功能完整的植物螯合素合酶和植物螯合素途径。通过表达pcs-1启动子标记的绿色荧光蛋白（pcs-1::GFP）的转基因线虫品系和pcs-1特异性定量PCR分析，进一步证明秀丽隐杆线虫植物螯合素合酶基因（pcs-1）的表达在转录水平上对高水平锌（500μM）的慢性（48小时）刺激或高水平镉（300μM）的急性（3小时）暴露无反应。然而，镉的积累（而非锌的积累）取决于线虫的pcs-1状态。基于同步加速器的X射线荧光成像发现，在pcs-1（tm1748）敲除等位基因中，镉的体内负荷显著增加。综上所述，这表明虽然pcs-1的转录可能不由锌或镉暴露介导，但它仍然是秀丽隐杆线虫镉解毒途径的一个组成部分。
