绿洲土Cd、Pb、Zn、Ni复合污染下重金属的形态特征和生物有效性

通过模拟基于干旱区绿洲土壤Cd-Pb-Zn-Ni复合污染下的油菜盆栽试验,采用Tessier五步连续浸提法探究了重金属复合污染对油菜生长的影响及其各形态的转化归趋和生物有效性.结果显示,随着Cd-Pb-Zn-Ni复合胁迫水平的升高,油菜的干重先增加后减小,根系的生长由促进作用转变为抑制作用;对照土壤中4种重金属元素均以残渣态为主要赋存形态,可交换态的含量均很小;随着外源重金属的添加,油菜种植土壤中4种重金属元素的各形态含量随之增加,Cd、Pb、Zn的可交换态和Ni的碳酸盐结合态对外界胁迫响应强度最大,Cd、Pb、Zn、Ni的活性增加,且Cd、Pb的主要赋存形态迅速转变为碳酸盐结合态和铁锰氧化态,Zn的主要赋存形态由残渣态和碳酸盐结合态过渡到碳酸盐结合态和铁锰氧化态,Ni的主要赋存形态为碳酸盐结合态;Cd、Zn在茎叶中的含量大于根系,Pb、Ni反之,油菜能将Cd、Zn更多的运输至茎叶,Pb、Ni则主要积累在根系;油菜茎叶吸收Cd和油菜各部位吸收Zn的主要贡献形态为可交换态,根吸收Cd的主要贡献形态由可交换态转变为有机结合态,根吸收Pb和油菜各部位吸收Ni的主要贡献形态为碳酸盐结合态.     

铜尾矿库区土壤与植物中重金属形态分析

对铜陵铜尾矿区土壤和植物中重金属形态进行了研究.结果表明,尾矿库区种植地极端贫瘠,有机质含量仅2.6～.8 g·kg^-1,而土壤Cu、Cd、Pb、Zn含量皆高于对照土壤,其中Cu含量达809.30～1 39.4 mg·kg^-1,Cd含量达3.2～6.3 mg·kg^-1,达到对照土壤30～60倍.结缕草和三叶草体内重金属含量与土壤重金属交换态及有机结合态含量成正相关,与碳酸盐结合态、铁锰氧化物结合态成显著或极显著负相关,与矿物态含量相关性不显著.在两种优势植物中,Cu、Zn、Pb均以活性较低的醋酸提取态、盐酸提取态和残渣态为主;Zn在根系和茎叶中,NaCl提取态占有较大比例,而Cd均以NaCl提取态为主.     

芜湖钢铁厂周边土壤及油菜籽中镉、铜、锌、铅含量和形态分布研究

研究了污染土壤、油菜籽中Cd、Cu、Zn、Pb含量、形态分布特征和重金属富集状况及可能存在的生物毒性.结果表明,土壤中Cd、Zn、Pb以铁锰氧化物结合态、Cu以残留态占5种形态最高比例,分别为31.1%、39.3%、53.79%、46.24%;Cd、Pb交换态比例较高,为23.47%、16.32%,Cu、Zn的交换态比例较小,为3.14%、0.54%;土壤中不同重金属与各重金属形态相关关系有差别,5种重金属形态转化为有效态重金属难易程度不同;油菜籽和油菜籽壳中不同重金属累积趋势有差异,Cu易在油菜籽壳中累积,Cd、Zn、Pb易在油菜籽中累积;油菜籽中不同重金属累积率不同,Cd累积率最高,为0.56.油菜籽中重金属累积率与土壤中重金属总量呈显著负相关关系(P＜0.05),土壤中重金属的形态、转化差异是此种负相关关系的主要原因;油菜籽中Cd、Cu、Pb以氯化钠态为主,分别为32.50%、22.94%、34.69%,Zn以EDTA态为主,为45.97%.油菜籽中重金属形态可能影响其毒性,但其毒性的人类膳食风险还需进一步研究证实.油菜籽中重金属形态与油菜中重金属总量相关性不好.     

海口城市土壤重金属污染特征与生态风险评估

对海口城市土壤重金属含量、空间分布特征与赋存形态进行了研究,并评估了其生态风险。结果表明,海口城市土壤重金属Hg、As、Cd、Cu、Cr、Ni、Pb、Zn的平均含量分别为0.073、3.82、0.25、26.7、92.4、52.5、29.1和84.1 mg·kg-1。与海口土壤背景值相比,海口城市土壤明显富集重金属Hg、As、Cd、Cu、Cr、Ni、Pb和Zn,受到一定程度重金属污染。Cr、Ni、Cu、Cd和Zn元素主要在郊区富集,Pb主要在路边绿化带中富集,Hg主要在生活区富集。海口城市土壤中Zn、As、Cr、Cu和Ni以残渣态为主,Hg主要以强有机态和残渣态存在,Pb主要以铁锰氧化态和残渣态存在,而Cd则主要以生物可利用态为主。生态风险评价结果显示,海口城市土壤重金属综合生态风险属于微弱水平,但Cd和Hg污染应引起重视。     

鄂尔多斯地区公路沿线土壤重金属形态与生物有效性

采用TessierA连续提取法对鄂尔多斯地区公路沿线土壤重金属（Pb、Zn、Cu、Ni、Cr）化学形态进行了测定。同时对土壤pH值、重金属含量和公路绿化植物重金属（Cd、Hg、Pb、Cu、Zn、Ni、Cr、As和Se）含量进行了分析，对该区域重金属的生物有效性与潜在生态风险进行预测。结果表明：土壤重金属有效态占总量百分比的大小序列为Zn〉Pb〉Ni、Cr〉Cu，与重金属元素在绿化植物中含量大小序列Zn〉Cu〉Ni、Cr、As、Pb〉Cd〉Hg并非完全趋于一致。不同公路段土壤重金属与其不同形态存在较大的变幅。公路沿线表层土壤中重金属的有效态占其总量为G109（东胜-准格尔段）15．7％～46．1％，G210（达拉特-东胜段）8．0％-40．9％，G109（东胜-鄂托克段）9．1％～33．9％，而且以有机态和Fe—Mn氧化结合态的比例较大，为各元素有效态的主要形态特征。Cu在不同植物不同器官中的含量较高，可能在鄂尔多斯地区特定环境条件下随植物的蒸腾拉力、水分和营养盐运移的生理生态作用下使其在植物体中富集。土壤重金属Zn的有效态含量较高，而残渣态含量低，须特别注意其对区域生态系统的潜在影响。     

施用污泥对土壤重金属形态分布和生物有效性的影响

采用盆栽技术和BCR连续浸提法研究了污泥的添加对土壤Cd、Pb、Cu和Zn形态分布的影响及重金属在黑麦草-施污泥土壤中迁移转化规律.结果表明:污泥的添加使土壤中生物有效态的Cd和Zn含量显著增加,生物有效态Pb含量显著降低,残渣态Pb的比例较CK增加了33.3％～74.5％,而可交换态和可还原态Cu含量在污泥与土壤添加比为1∶1时,仅占总量的0.7％和0.2％.污泥的添加能促进黑麦草对Cd、Cu和Zn的吸收,抑制对Pb的吸收.多元线性回归分析结果表明,黑麦草体内Cd、Zn和Cu含量分别与土壤中可还原态Cd、Zn和可氧化态Cu含量存在正相关,草体中Pb的含量则受土壤中可交换态和可氧化态Pb含量共同影响.种植黑麦草后根际土中可氧化态Cd和Cu分别向可交换态Cd和残渣态Cu转化,可交换态和可还原态Zn向可氧化态Zn转化,Pb的生物有效性基本未受影响.     

根际环境中铅的形态转化

用根际箱试验研究了红壤植麦和植稻后根际中Pb的形态转化 ,讨论了与Cd复合处理对Pb形态的影响 .结果表明 ,Pb在红壤根际、非根际的主要形态为酸解态 +碳酸盐态、交换态和铁锰氧化物结合态 .交换态Pb都是根际 >非根际 ;不同Pb处理浓度和Pb Cd交互作用都对Pb的形态分布产生影响 ,小麦根际随加入Cd浓度增大 ,根际交换态Pb和铁锰氧化物结合态Pb下降 ;水稻根际交换态Pb与Cd复合处理浓度密切相关 ,5mgCd·kg-1复合处理 ,根际交换态Pb的活化较单元素弱 ,10mgCd·kg-1复合处理 ,根际交换态Pb的活化较单元素要强 .     

鸡粪有机肥对设施菜地土壤重金属和微生物群落结构的影响

通过田间试验,研究在设施菜地上施用不同剂量的鸡粪有机肥对土壤-植物系统中重金属的累积、重金属有效性和土壤微生物群落结构的影响,进一步探讨土壤微生物群落结构与土壤重金属之间的相关关系。结果表明,与对照相比,施用有机肥可提高小白菜地上部生物量,其中施肥量为60 t/hm²时值最大,增幅为59.92%;小白菜地上部Cd、Cr、Cu、Zn和As含量均大幅增加,但Pb含量无明显变化。土壤重金属Cd、Cr、Cu、Zn和As的全量均随鸡粪有机肥施加量的增加而增大,最高增幅分别为21.30%、21.58%、17.40%、19.40%和17.43%,出现明显的累积现象;施用有机肥均增加了土壤Cd、Cr、Cu、Zn和As的有效态含量,而Pb的全量和有效态含量无显著变化;除重金属Pb外,不同重金属元素全量与有效态含量均显著正相关,其中元素Zn的全量与有效态含量相关性最强。磷脂脂肪酸（PLFA）分析结果表明,土壤中含量较高的PLFA为16：0、18：1ω7c、10Me16：0和18：1ω9c,土壤微生物总PLFA和各类群PLFA含量均呈现M0.5 > M1 > CK > M2 > M4;相关性分析结果表明,土壤Cu、As全量和Cd、Cr、Cu、As有效态含量与微生物总PLFA和各类群PLFA含量均呈现显著负相关关系,其中有效态Cr和Cu含量对微生物群落结构的影响最为显著。     

根瘤菌对土壤铜、锌和镉形态分配的影响

以湖南郴州红壤和河北巩义褐土为供试土壤。制备Cu、Zn、Cd污染土壤。接种大豆根瘤菌(Rhi-zobium fredii)HN01,用连续提取法浸提土壤中不同形态的重金属．结果表明。褐土接种根瘤菌后固相结合态Zn总量降低10％。专性吸附态、氧化锰结合态和有机结合态Zn减少达9％～26％．红壤中结合态Zn的总量变化不显著,但专性吸附态和氧化锰结合态Zn含量显著减少。交换态Zn含量显著增加．褐土中接种根瘤菌抑制了Cu向土壤溶液的释放,固相结合态Cu总量增加18％,可交换态、专性吸附态、氧化锰结合态和有机结合态的Cu增加20％～54％．接种根瘤菌对土壤中Cd的溶解没有明显的抑制或促进作用,但改变了红壤中各形态Cd的含量高低顺序．Cd污染红壤中可交换态和有机结合态Cd含量分别增加22％和11％,专性吸附态和氧化锰结合态Cd分别减少14％和29％．根瘤菌对不同类型重金属及不同土壤中重金属形态影响的差异主要与土壤pH降低有关．     

公路绿化植物油松(Pinus tabulaeformis)和小叶杨(Populus simonii)对重金属元素的吸收与积累

对内蒙古西部公路绿化植物油松（Pinus tabulaeformis）、小叶杨（Populus simonii）及其根际土壤中重金属元素（Cd、Hg、Pb、Cu、Zn、Ni、Cr）和类金属元素（As和Se）含量以及根际土壤重金属（Cu、Zn、Pb、Ni和Cr）形态、土壤pH值进行了测定。对比分析了公路沿线不同绿化植物及其不同器官对重金属元素的吸收与积累特征。结果表明：绿化植物根际土壤对重金属元素的吸附及污染程度以Cd为最高。随原子序数的递增,小叶杨和油松两种植物的根部和茎叶两种营养器官中重金属的含量均表现出“N”字形变动趋势。而且重金属元素在不同植物不同器官中的含量具有Zn〉Cu〉Ni,Cr,As,Pb〉Cd〉Hg的基本规律。小叶杨茎叶对重金属元素Cr、Ni和Pb的富集能力较根部为强,油松茎叶对重金属元素Cr、Ni、Cu和Pb的富集能力较根部为强。绿化植物根际土壤重金属元素有效态占总量百分比的大小序列为Zn〉Pb〉Ni、Cr〉Cu,与重金属元素在不同植物不同器官中的含量大小序列Zn〉Cu〉Ni、Cr、As、Pb〉Cd〉Hg并非趋于一致。公路绿化植物对根际土壤中重金属元素的吸收和积累与重金属元素有效态所占的比例有关。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.