急性低温对黑鲷抗氧化酶活性和 热休克蛋白含量的影响

为探究急性低温胁迫对黑鲷（Acanthopagrus schlegelii）生理机能的影响,以1龄黑鲷作为实验鱼,以15 ℃为对照组,设置10 ℃和5 ℃作为低温胁迫组,处理24 h后再转入15 ℃的水体中进行恢复实验,测定不同温度、不同时间点下1龄黑鲷肝的抗氧化酶活性以及热休克蛋白（Hsp）含量的变化。研究结果显示,低温胁迫实验中,低温处理组（10 ℃和5 ℃）在急性低温胁迫的24 h内,超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GSH-PX）活性和热休克蛋白含量均呈现先上升后下降的趋势。10 ℃处理组上述三种抗氧化酶活性皆在12 h达到最大值,超氧化物歧化酶、过氧化氢酶活性24 h恢复到对照水平,而谷胱甘肽过氧化物酶在18 h已经恢复到正常水平;在5 ℃处理组,超氧化物歧化酶和过氧化氢酶活性在6 h达到最大值,谷胱甘肽过氧化物酶在18 h达到最大值,且在24 h都仍与对照组有极显著差异,超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶活性分别在恢复实验的12 h、12 h和6 h恢复到对照组水平。10 ℃和5 ℃两个处理组的热休克蛋白含量皆在胁迫18 h达到最大,10 ℃处理组在24 h恢复到正常水平,但5 ℃处理组的热休克蛋白含量直到恢复实验结束仍与对照组存在差异。本实验结果表明,急性低温胁迫对超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化物酶和热休克蛋白具有显著影响,其均呈现有规律的变化趋势,说明上述酶和蛋白参与了黑鲷的低温胁迫应答过程,通过协同调节黑鲷的生理机能使其适应环境变化,减少急性低温对鱼体的损伤并使其能够在环境骤变情况下存活下来。只有在自我调节范围内,黑鲷随着胁迫时间的延长,其体内才能够建立新的生理平衡来适应低温,因此在黑鲷养殖过程中,应当注意水温不宜低于5 ℃,水温过低时,应尽快将其移入室内,避免水温骤降对鱼体造成损伤。     

外来入侵种飞机草在不同环境胁迫下抗氧化酶系统的变化

飞机草（Eupatorium odoratum）原产于中南美洲,在我国最早发现于1934年,目前已经分布到云南、海南、台湾、广东等省区,是一种典型的外来入侵种。研究其在逆境条件下的生理适应机制对于有效治理该入侵种具有十分重要的意义。研究了其在不同环境胁迫条件（高温、低温和干旱）下抗氧化酶系统的变化。结果表明：超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）和脱氢抗血酸还原酶（DHAR）在3种环境胁迫下酶活性都升高;过氧化氢酶（CAT）在高温胁迫下升高,而在低温和干旱胁迫下酶活性降低;过氧化物酶（POD）和单脱氢抗坏血酸还原酶（MDAR）在高温和干旱胁迫下酶活性升高,而在低温胁迫下酶活性降低;谷胱甘肽还原酶（GR）在高温和干旱胁迫下酶活性升高,而在低温胁迫下保持不变。这些研究结果可能有助于寻找到一条控制飞机草的新途径。     

茄无网蚜几种酶对溴氰菊酯与高温胁迫的应答

[目的]通过研究茄无网蚜Acyrthosiphon solani(Kaltenbach)在溴氰菊酯和高温2种胁迫方式下其单位虫体质量解毒酶、保护酶和代谢酶活力的变化情况,为茄无网蚜耐药性研究、发生期预测等提供相应的理论依据.[方法]本文用LC50溴氰菊酯和32℃高温分别胁迫3龄茄无网蚜6、12、24、48和72 h,分析并比较其单位虫体质量谷胱甘肽-S-转移酶、过氧化物酶、羧酸酯酶和海藻糖酶的活力变化.[结果]过氧化物酶和羧酸酯酶对2种胁迫方式的响应剧烈,单位虫体质量的过氧化物酶活力在茄无网蚜被溴氰菊酯胁迫6、24和48 h后被显著抑制(P＜0.05),在温度胁迫处理组中均高于对照组,且在6、12和24 h处理组差异显著(P＜0.05);羧酸酯酶活力在溴氰菊酯胁迫时有较大波动,在6、24、48和72 h处理组与对照差异显著(P＜0.05).海藻糖酶对2种胁迫方式的响应较剧烈,海藻糖酶活力在溴氰菊酯胁迫6、24、48和72 h处理组显著高于对照(P＜0.05),在温度胁迫6、12和72 h处理组与对照组差异显著(P＜0.05).谷胱甘肽-S-转移酶对2种胁迫方式的响应相对较弱,谷胱甘肽-S-转移酶活力仅在溴氰菊酯胁迫6h和24 h处理组与温度胁迫24 h处理组显著高于对照(P＜0.05).[结论]LC50溴氰菊酯胁迫比温度胁迫对茄无网蚜体内4种酶活力的影响更大;2种胁迫方式对茄元网蚜体内4种酶活性均产生影响,过氧化物酶与羧酸酯酶参与度更高.     

外来入侵种豚草对不同环境胁迫的生理响应

豚草（Ambrosia artemisiifolia）是一种外来入侵恶性杂草,本文研究了在人工模拟的不同环境胁迫（低温、高温、干旱和积水）下豚草叶片中丙二醛（MDA）和抗氧化系统的变化。结果表明：在4种环境胁迫下MDA含量、超氧化物歧化酶和过氧化氢酶活力都升高;过氧化氢酶活性在高温胁迫下升高,在其他3种胁迫下活性降低;还原型谷胱甘肽含量及抗超氧阴离子自由基活性在4种胁迫下降低。说明豚草抗逆机制多样,对高温、高湿的适应强,在华南及西南各省入侵潜力较大。     

温度胁迫对白桦悬浮细胞中三萜积累及防御酶活性的影响

以白桦悬浮培养细胞为试材,悬浮培养第7d进行高温(50℃热处理1h)和低温(4℃冷胁迫3h)胁迫处理,此后不同时间(0h～7d)收获白桦细胞,研究细胞干重、三萜积累及防御酶活性的变化。研究结果表明,高温和低温胁迫后均表现在24h～3d收获细胞显著促进了白桦总三萜的合成,且以高温处理效果最佳,48h收获细胞时分别比对照(25℃)和冷胁迫处理提高36.4%和12.87%;而在冷胁迫处理后4d～7d表现显著刺激了总三萜的合成,其中在第7d总三萜的含量比对照增加了22.1%,且两温度胁迫处理后15h～4d显著促进了齐墩果酸三萜的积累,24h收获时,热处理和冷胁迫均比对照提高38.1%和39.65%。两温度胁迫后不同程度促进了超氧化物岐化酶(SOD)、过氧化氢酶(CAT)、苯丙氨酸裂解酶(PAL)、过氧化物酶(POD)活性提高及丙二醛的积累,但各酶活性出现高峰及变化规律存在差异,明确各酶相互协调、补充是保证细胞适应温度胁迫,减轻自由基伤害,并促进次生产物合成的原因。     

冷锻炼对低温胁迫下夏威夷椰子膜脂过氧化及保护酶活性的影响

在－5℃低温胁迫下,夏威夷椰子（Pritchardia gaudichaudii H.Wendl.)幼苗叶片的丙二醛（MDA）含量逐渐增加,表明膜脂过氧化作用逐渐增强;含水量不断下降;细胞保护酶中的超氧化物歧化酶（SOD）、过氧化物酶（POD) 过氧化氢酶（CAT）酶活性均先升高,然后下降。冷锻炼处理可以减缓夏威夷椰子膜脂过氧化作用的增强,促进SOD酶活性的提高,同时抑制POD和CAT酶活性的变化,因而使夏威夷椰子幼苗的抗寒性得以提高,在－5℃低温胁迫下的半致死时间从1.6d延长到2.2d。     

温度对梯棱羊肚菌抗氧化酶活及其基因表达的影响

大田栽培条件下,环境温度无法精确调控,温度胁迫是影响羊肚菌生长发育的重要因素。抗氧化酶和抗氧化活性物质是羊肚菌抵御逆境胁迫的重要因子。温度胁迫下,羊肚菌菌丝会通过增加相应酶活性来减少活性氧的积累,降低对细胞的损伤。作者研究了不同温度对梯棱羊肚菌菌丝生长、抗氧化酶（超氧化物歧化酶SOD、过氧化氢酶CAT、谷胱甘肽还原酶GR、谷胱甘肽过氧化物酶GPX）活性及其基因表达和抗氧化活性物质的影响,结果显示：在5-25℃的温度区间内,随着温度的增加,菌丝生长速度加快,菌丝的老化速度也加快;对抗氧化酶活性研究发现,SOD、GPX和GR在低温下活性更高,CAT在高温下活性更高;抗氧化活性物质含量会随温度升高而增加,如还原型抗坏血酸（AsA）和还原型谷胱甘肽（GSH）;温度越高,羊肚菌菌丝中H₂O₂、O^2-和丙二醛含量也随之增加。因此,在温度胁迫下,羊肚菌通过启动不同的抗氧化酶和抗氧化活性物质来减少活性氧含量,缓解菌丝损伤,本研究为探讨温度对羊肚菌种质质量的影响和栽培条件优化提供了基础数据支撑。     

温度胁迫对小金蝠蛾幼虫抗氧化酶活性的影响

小金蝠蛾Hepialus xiaojinensis Tu.是我国名贵中药材冬虫夏草的寄主昆虫之一,适宜在高海拔低温地区(8℃-12℃)生存。本文研究了小金蝠蛾在不同温度(4℃、12℃、16℃、20℃、24℃、28℃)条件下处理4 h和12 h后4龄幼虫体内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、谷胱甘肽硫转移酶(GSTs)的活力变化,以及总抗氧化能力(T-AOC)和丙二醛(MDA)含量的变化。结果表明,小金蝠蛾在正常生长发育情况下SOD具有较高活性;经温度胁迫后,SOD活力持续维持在较高活性,CAT、POD活性以及T-AOC活性显著性升高(P0.05);GSTs在24℃以上活性有降低趋势,MDA含量有上升趋势。     

外源水杨酸对低温胁迫下火龙果幼苗的形态及生理效应

为探究外源水杨酸(SA)对低温胁迫下火龙果幼苗形态及生理的影响，该研究以‘紫红龙’火龙果幼苗为材料，将4个不同浓度的SA(0.1、0.3、0.5、0.7 mmol·L^-1)喷施叶片，48 h后4℃低温培养，于第0、第3、第6、第9天观察火龙果幼苗形态及叶片组织结构的变化，并测定叶片相对电导率、丙二醛含量、渗透调节物(可溶性糖、可溶性蛋白、脯氨酸)含量及抗氧化酶(超氧化物歧化酶、过氧化物酶、过氧化氢酶、谷胱甘肽S-转移酶)活性等生理指标。结果表明：(1)低温胁迫下，火龙果幼苗呈现0级、Ⅰ级和Ⅱ级3个冷害等级，SA处理后的火龙果幼苗出现Ⅰ级冷害和Ⅱ级冷害的株数百分率均明显降低。(2)与低温对照相比，SA处理能降低火龙果幼苗叶片相对电导率和丙二醛含量并提高渗透调节物含量和抗氧化酶活性。(3)通过对不同SA处理结果进行比较分析，发现缓解冷害症状、降低相对电导率和丙二醛含量、提高可溶性糖和脯氨酸的含量、提高超氧化物歧化酶和谷胱甘肽S-转移酶的活性均以0.3 mmol·L^-1 SA效果最好，提高可溶性蛋白含量、过氧化物酶活性、过氧化氢酶活性分别以0.7、...     

温度和紫外辐射胁迫对西藏飞蝗抗氧化系统的影响

为探讨西藏飞蝗(Locusta migratoria tibetensis Chen)对环境的适应机制,报道了温度和紫外辐射胁迫对西藏飞蝗抗氧化系统影响。以西藏飞蝗成虫为试材,研究5—20℃低温、30—45℃高温胁迫和紫外线辐射对其抗氧化酶活性和膜脂过氧化物丙二醛(MDA)含量的影响。在5—20℃低温胁迫下,成虫体壁和消化道超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性及丙二醛(MDA)含量分别随温度降低而升高;在30—35℃高温胁迫下,成虫SOD、POD和CAT活性分别随温度升高而升高,当温度超过35℃时,3种氧化酶活性均下降。长波紫外辐射(UV-A)和中波紫外辐射(UV-B)对处理后24h和72h成虫的SOD活性的影响大于可见光,在UV-A、UV-B和可见光3种光波长处理下,成虫的POD和CAT活性随光照时间的延长而增加,其中UV-B对两种酶活性影响大于UV-A和可见光,表现为UV-B处理组>UV-A处理组>可见光处理组;UV-A和UV-B处理能导致虫体体壁MDA含量明显升高,且对脂质过氧化的诱导存在时间效应;雌虫体壁、雌虫消化道、雄虫体壁和雄虫消化道的MDA含量分别在UV-B72h、UV-A72h、UV-A72h和UV-B72h达最大值0.72、0.88、0.66和0.94 nmol/g鲜重。在20—5℃低温胁迫下,西藏飞蝗成虫抗氧化酶活性升高,能较好的保护自身免遭活性氧自由基的伤害;西藏飞蝗对高温忍耐力差,在高于35℃高温胁迫下,成虫SOD、POD、CAT活性均下降;在长波和中波紫外辐射下,西藏飞蝗抗氧化酶活性显著升高,是西藏飞蝗对紫外线辐射强度大的青藏高原的一种重要适应。     

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.