四种绿化树种土壤酶活性对不同浓度多环芳烃的响应

多环芳烃(PAHs)是一类广泛存在于环境中的有机污染物, 由于其致癌性和致突变性而受到广泛关注.采用盆栽实验,在3种多环芳烃污染水平(重度L3 )、(中度L2)、(轻度L1)下,研究了樟树(Cinnamomum camphora)、广玉兰(Magnolia grandiflora)、栾树(Koelreuteria bipinnata)、马褂木(Liriodendron chinense)南方4种绿化树种的土壤酶活性在6个月后的响应差异.结果表明:在不同PAHs污染水平下,磷酸酶活性表现为L2＞L3＞ L1;多酚氧化酶和过氧化氢酶的趋势一致,表现为L3＞L1＞ L2.土壤酶活性在4个树种间有明显差异,在L1污染水平下,各土壤酶活性表现为马褂木＞广玉兰＞樟树＞栾树;在L2污染水平下,各土壤酶活性表现为栾树＞马褂木＞樟树＞广玉兰;而在L3污染水平下,表现为马褂木＞樟树＞广玉兰＞栾树.不同PAHs水平下的多酚氧化酶活性呈极显著差异(P＜0.01),过氧化氢酶活性呈显著差异(P＜0.05),而磷酸酶活性变化率受污染物浓度影响不显著.此外,土壤酶活性与微生物相关性不显著.土壤过氧化氢酶和多酚氧化酶可以作为土壤污染程度的评价指标.     

根际促生菌及木质素对持久性有机污染土壤修复的调控和酶活性的影响

近年来,持久性有机污染物对农田污染状况加剧,对人类食品安全和身体健康造成严重威胁。本实验以温室蔬菜基地中老化的有机污染土壤为目标,选取了DDTs和PAHs两种典型持久性有机污染物为去除对象,运用原位实验,研究了不同调控措施对有机污染土壤的修复效果及土壤酶活性的变化情况,并对污染物去除率与酶活性变化进行了相关性分析。结果表明,根际促生菌和木质素共同调控下的鼠李糖脂强化植物-微生物联合修复方法对有机污染物的去除效果最好,DDTs去除率为27.48%,PAHs去除率为53.26%;修复结束后,土壤多酚氧化酶、过氧化氢酶均被激活,激活程度表现为过氧化氢酶多酚氧化酶,磷酸酶活性被抑制,使用Pearson双变量法对土壤酶活性与污染物去除率进行统计学分析发现,多酚氧化酶、磷酸酶与DDTs和PAHs去除率存在较好相关性,因此可以将这两种酶活性定义为修复过程中的一项微生态指标。     

铜陵铜矿区凤丹根际和非根际土壤酶活性

对铜陵铜矿区凤丹根际和非根际土壤酶活性特征进行了研究.结果表明,凤丹根际土壤各种酶活性显著大于非根际土壤.凤丹非根际土壤过氧化氢酶、磷酸酶和脲酶活性能敏感地反映土壤重金属复合污染状况;根际环境对土壤酶活性的影响表现为: 磷酸酶＞脲酶＞过氧化氢酶＞蔗糖酶＞多酚氧化酶,影响率分别为131.562%、92.492%、87.557%、59.673%34.076%;土壤各种酶活性与重金属复合污染程度呈显著负相关,相关系数均-0.868以上,表现出重金属复合污染对土壤酶活性的抑制效应.凤丹可有效地改善土壤环境,提高土壤各种酶的活性.     

重金属污染区土壤酶活性变化——以福建龙岩新罗区特钢厂污水灌溉区为例

从福建龙岩新罗区特钢厂污灌区农田采集土壤,测定土壤基本理化性质及脲酶、纤维素酶、碱性磷酸酶、多酚氧化酶、过氧化氢酶活性和Cu、Cd、Pb、Zn含量,探讨重金属污染和土壤性质对土壤酶活性的影响.结果表明:4种全量或有效态重金属与土壤脲酶、纤维素酶、碱性磷酸酶和多酚氧化酶活性呈显著正相关,与过氧化氢酶活性呈显著或极显著负相关;土壤pH与碱性磷酸酶活性呈极显著正相关,粉粒含量与过氧化氢酶活性呈显著负相关.经通径分析,重金属污染刺激了脲酶、多酚氧化酶和纤维素酶活性,但对碱性磷酸酶活性的影响较小.有效态Cu、Cd、Pb、zn对过氧化氢酶活性的直接影响并不大,但通过间接途径抑制了过氧化氢酶活性.土壤理化性质对5种土壤酶活性的影响较大,碱解氮直接抑制了脲酶活性;全磷直接刺激了碱性磷酸酶和过氧化氢酶活性,并通过有效磷刺激了纤维素酶活性;有效磷直接刺激了纤维素酶活性,直接抑制了碱性磷酸酶和过氧化氢酶活性;全钾直接抑制了碱性磷酸酶和多酚氧化酶活性;速效钾通过有效磷刺激了纤维素酶活性;土壤颗粒组成明显影响多酚氧化酶和过氧化氢酶活性.5种酶活性与土壤Cu、Cd、Pb、Zn含量之间的关系不明确,因此其活性不是指示土壤Cu、Cd、Pb、Zn污染的良好指标.     

模拟氮沉降对温带森林土壤酶活性的影响

森林土壤酶作为土壤中最活跃组分,能影响生态系统的物质循环过程,其活性能快速反映氮沉降对土壤环境的变化。以北京地带性植被辽东栎林为研究对象,利用模拟氮沉降方法,原位设计低氮(50 kg N hm~(-2)a~(-1),N50)、高氮(150 kg N hm~(-2)a~(-1),N150)两个施氮水平,每个施氮水平设置Na NO_3、(NH_4)_2SO_4、NH4NO_33个不同的施氮类型,另设置空白对照(0 kg N hm~(-2)a~(-1),N0)。从时间格局上研究不同氮素化学形态和剂量对温带森林土壤6种酶(脲酶、酸性磷酸酶、碱性磷酸酶、β-葡萄糖苷酶、多酚氧化酶和过氧化氢酶)活性的影响。结果表明:在氮形态和水平的交互作用下,NH4NO3-N处理的脲酶活性显著高出NO~-_3-N处理的24.20%(N50),NH~+_4-N处理对酸性磷酸酶活性的影响显著高出NO~-_3-N处理的13.82%(N150);在NH~+_4-N和NH_4NO_3-N处理中,N50水平下的脲酶活性分别高出N0处理的38.90%和24.20%,差异显著。对无氮形态和水平交互作用的酶活性分析得出,不同的施氮水平,对碱性磷酸酶和多酚氧化酶的酶活性有显著促进作用,碱性磷酸酶活性在N50和N150处理下分别比N0高20.2%和11.5%,N50和N150处理对多酚氧化酶活性的促进作用分别比N0处理高64.3%和41.8%,差异显著(P0.05);NH~+_4-N处理对β-葡萄糖苷酶活性具有显著促进作用(P0.05),不同的施氮形态,对碱性磷酸酶、多酚氧化酶和过氧化氢酶的酶活性无显著影响。6种酶活性均呈现了显著的时间变化,氮添加对森林土壤酶活性的时间分异规律没有显著影响。此外,土壤微生物量碳、硝态氮和铵态氮含量与酶活性具有显著相关性(P0.05)。以上结果表明,氮添加通过改变森林土壤的环境因子,影响了土壤中的水解酶和氧化酶活性,进而改变了土壤有机碳库和养分循环。     

重金属污染区土壤酶活性变化

从福建龙岩新罗区特钢厂污灌区农田采集土壤,测定土壤基本理化性质及脲酶、纤维素酶、碱性磷酸酶、多酚氧化酶、过氧化氢酶活性和Cu、Cd、Pb、Zn含量,探讨重金属污染和土壤性质对土壤酶活性的影响.结果表明： 4种全量或有效态重金属与土壤脲酶、纤维素酶、碱性磷酸酶和多酚氧化酶活性呈显著正相关,与过氧化氢酶活性呈显著或极显著负相关;土壤pH与碱性磷酸酶活性呈极显著正相关,粉粒含量与过氧化氢酶活性呈显著负相关.经通径分析,重金属污染刺激了脲酶、多酚氧化酶和纤维素酶活性,但对碱性磷酸酶活性的影响较小.有效态Cu、Cd、Pb、Zn对过氧化氢酶活性的直接影响并不大,但通过间接途径抑制了过氧化氢酶活性.土壤理化性质对5种土壤酶活性的影响较大,碱解氮直接抑制了脲酶活性;全磷直接刺激了碱性磷酸酶和过氧化氢酶活性,并通过有效磷刺激了纤维素酶活性;有效磷直接刺激了纤维素酶活性,直接抑制了碱性磷酸酶和过氧化氢酶活性;全钾直接抑制了碱性磷酸酶和多酚氧化酶活性;速效钾通过有效磷刺激了纤维素酶活性;土壤颗粒组成明显影响多酚氧化酶和过氧化氢酶活性.5种酶活性与土壤Cu、Cd、Pb、Zn含量之间的关系不明确,因此其活性不是指示土壤Cu、Cd、Pb、Zn污染的良好指标.     

长期灌溉含多环芳烃污水对稻田土壤酶活性与微生物种群数量的影响

以沈抚污水灌区为例,研究了长期灌溉含多环芳烃(PAHs)污水对稻田土壤酶活性、微生物种群数量的影响。结果表明,灌区稻田土壤PAHs含量在319.5～6362.8μg.kg-1。长期污水灌溉导致稻田土壤PAHs含量严重超过环境标准。随清水连续灌溉年限的增加,土壤PAHs总量不同程度降低直至低于土壤PAHs环境质量标准。相关性分析表明,在目前污染程度下,灌区稻田3大土壤微生物类群和主要功能群的种群数量主要受土壤理化性质的影响,受PAHs含量影响不明显。土壤全氮含量与细菌数量呈极显著正相关(P<0.01)。土壤酶活性受到土壤养分和PAHs污染的双重影响,土壤有机碳和全磷含量分别与脱氢酶、多酚氧化酶和脲酶活性呈极显著正相关(P<0.01),PAHs含量分别与脱氢酶和脲酶活性呈极显著正相关(P<0.01),与多酚氧化酶活性呈显著正相关(P<0.05)。     

喀斯特退化山地不同类型人工林土壤养分与酶活性

人工植被恢复是喀斯特退化山地生态修复的重要途径之一。本研究探讨了喀斯特山地滇柏(Cupressus duclouxiana)纯林、刺槐(Robinia pseudoacacia)纯林和滇柏-刺槐混交林等3种类型人工林和未造林地(对照)的土壤养分含量和土壤酶活性及其相关性,为该地区选择适宜的造林树种和方式、改善林地土壤质量提供参考依据。结果表明：(1)4种类型样地土壤均呈碱性,且人工林土壤pH值均显著低于未造林地;人工林土壤有机质、全氮、碱解氮、有效磷含量均显著高于未造林地;全钾、速效钾含量均显著低于未造林地。(2)除碱性磷酸酶外,其余4种土壤酶活性均在滇柏-刺槐混交林中最大。3种类型人工林土壤脲酶、碱性磷酸酶、过氧化氢酶活性均高于未造林地。(3)脲酶、多酚氧化酶、蔗糖酶、碱性磷酸酶等受土壤养分影响的主要因素不同,过氧化氢酶活性与养分指标之间相关性不显著。(4)冗余分析结果表明,土壤全氮、全磷对喀斯特不同类型林分土壤酶活性影响显著,能解释酶活性变异的60.7%,酶活性-养分特征关系方差累计贡献率为78.8%。喀斯特退化山地营建的人工林植被可提高林地土壤养分含量与酶活性,从而改善土壤质量,...     

石油污染土壤的生物修复与土壤酶活性关系

研究了不同油浓度污染土壤经过两个为期125d的生物修复后的土壤中过氧化氢酶、多酚氧化酶和脂肪酶的酶活变化,分析了土壤中3种酶活性的变化特征与规律。结果表明,随着油浓度的增加,土壤中过氧化氢酶和多酚氧化酶的活性下降,脂肪酶活性增加;经过生物修复后,土壤中的过氧化氢酶和多酚氧化酶的活性在第二周期要比第一周期提高,而脂肪酶活性下降;这3种土壤酶活性变化受污染物浓度影响不显著,但不同浓度油污染土壤的修复对过氧化氢酶的影响要大于对多酚氧化酶和脂肪酶的影响。     

猫儿山不同海拔典型植被带土壤酶活性变化特征

为研究猫儿山不同海拔典型植被带土壤酶活性的变化规律,对该保护区内4个不同海拔植被带的5种土壤酶活性进行了分析测定。结果表明:随着海拔的上升,土壤磷酸酶、多酚氧化酶和过氧化氢酶活性随海拔上升呈递增趋势,而土壤脲酶和蔗糖酶活性呈递减趋势。不同海拔植被带土壤酶活性与土壤理化性质的相关性分析结果表明,除了全磷外,土壤过氧化氢酶活性与其它理化性质之间的相关性均达到显著或极显著水平。土壤过氧化氢酶活性与脲酶和蔗糖酶活性之间呈显著负相关关系。土壤过氧化氢酶活性与土壤理化性质及其它酶活性之间的相关性最为显著。猫儿山不同海拔典型植被带土壤酶活性呈现一定的变化规律,该结果揭示了不同海拔土壤酶活性的差异及空间分布特点,为猫儿山不同海拔森林土壤的利用和改良提供理论依据。     

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.