重金属对油菜种子萌发和胚根生长的影响

分析了Hg2 、Cd2 、Ni2 、Co2 、Zn2 5种重金属离子对油菜种子萌发和胚根伸长的影响,以及金属离子K 、Mg2 和Ca2 与重金属的交互作用。结果表明:(1)重金属对油菜种子萌发的抑制作用依次为Hg2 >Cd2 和Co2 >Ni2 >Zn2 ,而对胚根生长的毒害作用依次为Hg2 >Cd2 >Co2 >Ni2 >Zn2 。(2)萌发率为40%以上时,K 和Ca2 可以提高Ni2 、Zn2 和Co2 胁迫下油菜种子的萌发率,却进一步降低了Hg2 、Cd2 胁迫下种子的萌发;Mg2 可以提高Ni2 、Zn2 、Cd2 和Co2 胁迫下种子的萌发率,但对Hg2 毒害却没有缓解。(3)胚根伸长率达到60%以上时,K 和Mg2 增强了Ni2 、Hg2 、Cd2 和Co2 对胚根生长的抑制,而Ca2 则缓解了Zn2 、Ni2 和Co2 对胚根生长的抑制作用。研究结果对于重金属复合污染土壤中植物种子的萌发和定植具有理论和实践意义。     

大肠杆菌CusS的生物信息学分析及对银离子胁迫的响应

【目的】解析大肠杆菌(Escherichia coli) K-12菌株同型二聚体内膜传感器组氨酸激酶(sensor histidine kinase, CusS)蛋白在细菌应答金属银离子胁迫中的调控机制,为该菌的防治提供重要科学依据。【方法】利用ProtParam、ProtScale、Protein-Sol、TMHMM、SignalP、LocTree3、NetNGlyc-1.0、NetPhosBac-3.0、SOPMA、I-TASSERF、STRING和MEGA分别预测CusS的理化性质、亲水性、可溶性、跨膜域、信号肽、亚细胞定位、糖基化位点、磷酸化位点、二级结构、三级结构、蛋白互作的关系网络和蛋白在革兰阴性杆菌中的同源性。采用Red同源重组技术构建大肠杆菌ΔcusS,在不同培养基中连续监测ΔcusS的生长情况,观察该基因缺失后的细菌生长活性;通过最小抑菌浓度(minimal inhibitory concentration, MIC)试验评价该缺失株对金属铜、银离子和临床常见抗生素的敏感性变化;运用RT-qPCR检测cusS缺失后其下游基因cusCFBA和cusR转录水平。【结果】CusS蛋白由480个氨基酸组成,相对分子质量为53 738.05,原子总数为7 624,等电点为6.02,具有稳定性,是一种亲水性、不溶性蛋白;含有跨膜域;不存在信号肽,定位于细胞内膜中;存在2个糖基化位点、24个丝氨酸磷酸化位点、14个苏氨酸磷酸化位点和3个酪氨酸磷酸化位点;二级结构中α-螺旋占比55.42%,β-折叠占比11.67%,β-转角占比3.75%,无规则卷曲占比29.17%;cusS在埃希菌属和志贺菌属中的保守性高;菌落PCR和一代测序验证ΔcusS构建成功;连续检测生长曲线表明cusS缺失并不影响细菌的生长代谢,但CusS蛋白为大肠杆菌抵御金属银胁迫的关键基因。【结论】cusS作为一个关键基因,它的缺失并不影响大肠杆菌的生长活性,但会显著降低细菌抵御银离子胁迫的应答能力。缺失cusS将使下游基因cusCFBA和cusR的mRNA表达水平显著下降。对CusS蛋白进行生物信息学分析及表型初探,为深入了解CusS在大肠杆菌应答银离子胁迫的调控机制奠定了基础。     

Imaging mass spectroscopy delineates the thinned and thickened walls of intracranial aneurysms

Object

The wall thickness of intracranial aneurysms (IAs) is heterogeneous. Although thinning of the IA wall is thought to contribute to IA rupture, the underlying mechanism remains poorly understood. Recently, imaging mass spectroscopy (IMS) has been used to reveal the distribution of phospholipids in vascular diseases. To investigate the feature of phospholipid composition of IA walls, we conducted IMS in a rat model of experimentally induced IA.

5种湿地植物对土壤重金属的富集转运特征

选择芦苇、水葱、千屈菜、扁秆藨草、长苞香蒲5种湿地植物进行盆栽实验,比较它们对土壤中的5种重金属镉、铬、汞、铅、锌的富集特性,分析重金属在各植物体和土壤中的动态分布,以评价所测植物对土壤中重金属的综合富集能力,为利用植物修复金属污染土壤提供理论依据和技术支持。结果表明:(1)种植湿地植物对土壤重金属的富集效果显著高于无植物对照,且随着处理时间的延长,土壤中重金属镉、铬、汞、铅、锌的含量均呈下降趋势。(2)湿地植物对重金属镉、铬、汞、铅、锌的富集效果差异显著,其中水葱根部对重金属镉的富集系数最大,芦苇根部对重金属铬、汞、铅、锌的富集系数均最大,千屈菜、扁秆藨草和长苞香蒲根部对5种重金属的富集系数均较小;芦苇地上部分对金属镉的富集系数最大,千屈菜地上部分对金属铬、汞、铅的富集系数均最大,水葱地上部分对金属锌的富集系数最大。(3)5种湿地植物对重金属镉、铬、汞、铅、锌的转移系数差异显著,其中扁秆藨草对土壤中镉、铬、铅、锌的转移系数均为最大,对铬和锌的转移系数均大于1,长苞香蒲对铬的转移系数大于1,仅次于扁秆藨草。其他3种植物对5种重金属的转移系数均小于1。研究表明,5种湿地植物对重金属Cd、Cr、Hg、Pb、Zn都有富集和转移的能力,但不同植物对不同重金属的富集效果不同。     

贵州兴仁煤矿区农田土壤重金属化学形态及风险评估

为了解煤矿区周边农田土壤重金属污染状况,采集了贵州省兴仁县某典型煤矿区农田土壤样品64份,测定了土样中重金属(As、Cr、Pb、Zn、Cd、Hg、Cu、Ni)总量及各形态含量,采用单因子指数法、潜在生态风险指数法(Hkanson法)和风险评估编码法(RAC)对研究区主要土壤利用类型(水稻土、薏米地、植烟土和菜园土)中重金属进行潜在生态风险评估和环境风险评价.结果表明： 不同利用类型土壤中重金属含量除Zn外,其他元素均明显超过贵州省背景值.单因子指数法评价结果表明,As、Pb、Hg和Cu污染较为严重,均属重度污染.形态分析表明,土壤中重金属形态构成差异明显,酸可提取态As、酸可提取态Cd所占比例较高;Cr、Zn、Cu、Ni主要以残渣态为主;Pb主要以可还原态和残渣态为主;而Hg的酸可提取态、可还原态、可氧化态均占有相当比例,三者之和大于55%.重金属可利用度大小顺序为:As(63.6%)>Hg(57.3%)>Cd(56.4%)>Pb(52.5%)>Cu(45.7%)>Zn(32.8%)>Ni(26.2%)>Cr(13.2%).潜在生态风险指数表明,各类型土壤潜在生态风险(RI)〖JP2〗为:菜园土(505.19)>薏米地(486.06)>植烟土(475.33)>水稻土(446.86),均处于较高风险.风险评估编码法结果显示,As在水稻土、薏米地及植烟土中均处于高风险,在菜园土中处于中等风险;Cd、Hg均处于中等风险,Cr、Pb、Zn、Cu和Ni均处于低风险.因此,对该区域农田土壤进行管控时应重点考虑As、Cd和Hg污染.     

A Jonah-like chymotrypsin from the therapeutic maggot Lucilia sericata plays a role in wound debridement and coagulation

Lucilia sericata larvae are used in maggot debridement therapy, a traditional wound healing approach that has recently been approved for the treatment of chronic wounds. Maggot excretion products (MEP) contain many different proteases that promote disinfection, debridement and the acceleration of wound healing, e.g. by activating the host contact phase/intrinsic pathway of coagulation. In order to characterise relevant procoagulant proteases, we analysed MEP and identified a chymotrypsin-like serine protease with similarities to Jonah proteases from Drosophila melanogaster and a chymotrypsin from Lucilia cuprina. A recombinant form of the L. sericata Jonah chymotrypsin was produced in Escherichia coli. The activated enzyme (Jonah_m) had a pH optimum of 8.0 and a temperature optimum of 37 °C, based on the cleavage of the chromogenic peptide s-7388 and casein. Jonah_m reduced the clotting time of human plasma even in the absence of the endogenous protease kallikrein, factor XI or factor XII and digested the extracellular matrix proteins fibronectin, laminin and collagen IV, suggesting a potential mechanism of wound debridement. Based on these characteristics, the novel L. sericata chymotrypsin-like serine protease appears to be an ideal candidate for the development of topical drugs for wound healing applications.     

Heavy metal accumulation in wheat and barley: The effects of soil presence and liquid manure amendment

An experiment was undertaken to evaluate the effect of liquid manure amendment on heavy metal accumulation in wheat and barley. For this purpose, both kinds of seedlings were grown simultaneously in a Petri dish, while wheat seedlings were also grown in pots containing unpolluted agricultural soil. All of the seedlings were irrigated with one of the three prepared solutions: artificial rainwater solution, heavy metal solution and liquid manure solution containing NH₄NO₃, H₃PO₄ and KOH along with equal amounts of heavy metals as in the second solution. Twenty days later, 1 g of plant tissue was digested with the mixture of HNO₃ and H₂O₂ for ICP-OES/HG-ICP-OES analysis. The results showed that the uptake of arsenic and mercury was highest for both plants grown in a Petri dish. Furthermore, the wheat grown in a Petri dish also had a high content of nickel, cadmium and copper, while the pot-grown wheat contained high amounts of iron and manganese, probably due to the adsorption of nickel, cadmium, copper and mercury on soil phases. The lower uptake of all heavy metals was observed after the amendment of liquid manure, with the exception of manganese in wheat and mercury in all plants.