Amooaghaie Rayhaneh, Tabatabaei Fatemeh, Ahadi Ali-Mohammad
Biology Department, Science Faculty, Shahrekord University, Shahrekord, Iran.
Biology Department, Science Faculty, Shahrekord University, Shahrekord, Iran.
Ecotoxicol Environ Saf. 2015 Mar;113:259-70. doi: 10.1016/j.ecoenv.2014.12.017. Epub 2014 Dec 17.
Silver nanoparticles (AgNPs) are one of the most widely used nanomaterials, although the mechanisms of AgNP toxicity in terrestrial plants is still unclear. We compared the toxic effects of AgNPs and AgNO3 on Brassica nigra seed germination at physiological and molecular levels. Both AgNPs and AgNO3 inhibited seed germination, lipase activity, soluble and reducing sugar contents in germinating seeds and seedlings. These reductions were more pronounced in AgNP treatments than AgNO3 treatments. Application of 200-400mg/L both AgNPs and AgNO3 increased transcription of heme oxygenase-1. However, at 800, 1600 mg/L, AgNPs or AgNO3 suppressed HO-1 expression. At 400mg/L, AgNPs or AgNO3-induced inhibitory effects on seed germination and were ameliorated by the HO-1 inducer, hematin, or NO donor, sodium nitroprusside (SNP). Additionally, 4 μM hematin and 400 μM SNP were able to markedly boost the HO/NO system. However, the addition of the HO-1 inhibitor (ZnPPIX) or the specific scavenger of NO (cPTIO) not only reversed the protective effects conferred by hematin, but also blocked the up-regulation of HO activity. In addition, hematin-drived NO production in B. niger seeds under AgNPs was confirmed. Our results at physiological and molecular levels suggested that AgNPs were more toxic than AgNO3. Based on these results, for the first time, we suggest that endogenous HO is needed to alleviate AgNPs-induced germination inhibition, which might have a possible interaction with NO.
银纳米颗粒（AgNPs）是应用最为广泛的纳米材料之一，尽管AgNP对陆生植物的毒性机制仍不清楚。我们在生理和分子水平上比较了AgNPs和AgNO₃对黑芥种子萌发的毒性作用。AgNPs和AgNO₃均抑制种子萌发、脂肪酶活性、发芽种子和幼苗中的可溶性糖和还原糖含量。这些降低在AgNP处理中比AgNO₃处理中更为明显。200 - 400mg/L的AgNPs和AgNO₃处理均增加了血红素加氧酶-1的转录。然而，在800、1600mg/L时，AgNPs或AgNO₃抑制了HO-1的表达。在400mg/L时，AgNPs或AgNO₃对种子萌发的抑制作用可被HO-1诱导剂血晶素或NO供体硝普钠（SNP）改善。此外，4μM血晶素和400μM SNP能够显著增强HO/NO系统。然而，添加HO-1抑制剂（ZnPPIX）或NO的特异性清除剂（cPTIO）不仅逆转了血晶素赋予的保护作用，还阻断了HO活性的上调。此外，证实了在AgNPs作用下黑芥种子中血晶素驱动的NO产生。我们在生理和分子水平上的结果表明，AgNPs比AgNO₃毒性更大。基于这些结果，我们首次表明，需要内源性HO来减轻AgNPs诱导的萌发抑制，这可能与NO存在相互作用。
