College of Life Science, Hunan Normal University, Changsha, 410006, Hunan, China.
College of Resources and Environment, Hunan Agriculture University, Changsha, 410128, Hunan, China.
Environ Pollut. 2021 Jan 1;268(Pt A):115847. doi: 10.1016/j.envpol.2020.115847. Epub 2020 Oct 20.
Cadmium (Cd) pollution is currently the most serious type of heavy metal pollution throughout the world. Previous studies have shown that Cd elevates the mortality of paddy field spiders, but the lethal mechanism remains to be explored profoundly. In the present study, we measured the activities of protective enzymes (acetylcholinesterase, glutathione peroxidase, phenol oxidase) and a heavy metal chelating protein (metallothionein) in the pond wolf spider Pardosa pseudoannulata after Cd exposure. The results indicated that Cd initially increased the enzyme activities and protein concentration of the spider after 10- and 20-day exposure before inhibiting them at 30-day exposure. Further analysis showed that the enzyme activities in the cephalothorax were inhibited to some extent. Since the cephalothorax region contains important venom glands, we performed transcriptome sequencing (RNA-seq) analysis of the venom glands collected from the spiders after long-term Cd exposure. RNA-seq yielded a total of 2826 differentially expressed genes (DEGs), and most of the DEGs were annotated into the process of protein synthesis, processing and degradation. Furthermore, a mass of genes involved in protein recognition and endoplasmic reticulum (ER) -associated protein degradation were down-regulated. The reduction of protease activities supports the view that protein synthesis and degradation in organelles and cytoplasm were dramatically inhibited. Collectively, our outcomes illustrate that Cd poses adverse effects on the expression of protective enzymes and protein, which potentially down-regulates the immune function in the venom glands of the spiders via the alteration of protein processing and degradation in the ER.
镉（Cd）污染是目前全世界最严重的重金属污染类型之一。先前的研究表明，Cd 会增加稻田蜘蛛的死亡率，但致死机制仍有待深入研究。本研究测定了 Cd 暴露后池狼蛛 Pardosa pseudoannulata 体内保护酶（乙酰胆碱酯酶、谷胱甘肽过氧化物酶、酚氧化酶）和重金属螯合蛋白（金属硫蛋白）的活性。结果表明，Cd 在暴露 10 天和 20 天后，蜘蛛的酶活性和蛋白浓度先升高，然后在 30 天暴露时受到抑制。进一步的分析表明，头胸部的酶活性受到了一定程度的抑制。由于头胸部区域含有重要的毒腺，我们对长期 Cd 暴露后蜘蛛毒腺采集的样本进行了转录组测序（RNA-seq）分析。RNA-seq 共获得了 2826 个差异表达基因（DEGs），大多数 DEGs 被注释为蛋白质合成、加工和降解过程。此外，大量与蛋白质识别和内质网（ER）相关蛋白降解相关的基因下调。蛋白酶活性的降低支持了这样一种观点，即细胞器和细胞质中的蛋白质合成和降解受到了显著抑制。综上所述，我们的研究结果表明，Cd 对保护酶和蛋白的表达产生了不利影响，通过改变 ER 中蛋白质的加工和降解，可能会下调蜘蛛毒腺的免疫功能。
