低温对不同耐寒力的黄瓜(Cucumic sativus)幼苗子叶各细胞器中超氧物歧化酶(SOD)的影响

黄瓜幼苗子叶SOD活性在细胞内的分布是细胞溶质部份最高(占总活性的85％左右),其次是线粒体(占10％)和叶绿体(约4％)。各细胞器的SOD同工酶酶谱均为三条同工酶活性带,迁移率较慢的一条是Mn-SOD同工酶,迁移率较快的二条为CuZn-SOD同工酶。各细胞器的SOD对低温的敏感程度不同,依次为:叶绿体>线粒体>细胞溶质部份。叶绿体和线粒体周工酶酶谱的CuZn-SOD活性带,随着处理温度的降低而减弱或接近消失。随着温度的降低,黄瓜幼苗子叶SOD活性的下降和电解质泄漏增加,幼苗逐渐呈现出伤害症状,而SOD活性的显著下降却比细胞电解质大量泄漏的出现要早。耐寒力不同的两个品种在SOD活性及电解质泄漏的变化上有差异。     

低温对杂优水稻及其亲本幼苗中超氧物歧化酶的影响

本试验表明,超氧物歧化酶(SOD)普遍存在于“杂优”水稻及其亲本的叶绿体、线粒体及细胞溶质中。在细胞溶质和线粒体中分离出三条 Cu-Zn-SOD 和一条 Mn-SOD 的同工酶,而叶绿体中只分离出三条 Cu-Zn-SOD 的同工酶。各细胞器以叶绿体中的 SOD 对低温反应最敏感,线粒体次之。杂交后代(F_1)叶绿体的 SOD 对低温的敏感性接近母本。     

超氧物歧化酶(SOD)在大豆下胚轴线粒体内的定位

本文介绍一种简单有效的制备、分离植物线粒体分部的方法,根据这一方法证明了大豆下胚轴线粒体内的 SOD 主要在基质可溶性部分,是属于对氰化物不敏感的 Mn-SOD,它占线粒体 SOD 总活性的80%,其余 SOD 活性主要在线粒体的膜间空间,约占总活性的16%。结果表明,SOD 在植物线粒体内的分布和定位与动物组织相似。     

大豆和花生种子超氧物歧化酶的同工酶研究

大豆种子超氧物歧化酶(SOD)同工酶谱带有7～8条,花生有5条,它们当中电泳迁移率最低的一条属于Mn-SOD,其余的都是Cu-Zn-SOD。 Mn-SOD在pH 3和pH 12时,很快丧失催化活性,而Cu-Zn-SOD能在一定时间内保持催化活力。经纯化的SOD同工酶的催化活性对pH的改变更为敏感。 酶液在存放过程和高温处理时,Cu-Zn-SOD的催化活性比Mn-SOD有较好稳定性。 在变性剂SDS作用下,Cu-Zn-SOD能保持催化活性而Mn-SOD活力丧失;相比之下,β-巯基乙醇使Cu-Zn-SOD失活而Mn-SOD仍有部分活力。8M脲存在时,SOD活力普遍下降,但Cu-Zn-SOD比Mn-SOD下降更厉害。SOD和β-巯基乙醇同时存在时,全部SOD同工酶完全失活。     

几种外源因子对大豆幼苗SOD活性的影响

高氧能促使大豆幼苗细胞内产生O_2~+速率增加,同时又使幼苗内SOD活性水平提高,以减轻O_2~+增加所引起的细胞伤害。高氧诱发O_2~+同时发生在叶绿体、线粒体和细胞溶质中,与细胞呼吸水平无明显相关。棓酸丙酯有清除体内O_2~+的能力,当浓度在1μmol/L时,能减轻大豆幼苗的氧伤害。相反,DDC是SOD的有效抑制剂,当它的浓度大于5 mmol/L时,显著抑制大豆幼苗SOD活性,增加了体内O_2~+的积累,影响了幼苗的正常生长以及幼苗氧伤害的加剧。     

不同进化类型大豆种子超氧物歧化酶的比较

本文对不同进化类型大豆种子超氧物歧化酶(SOD)进行了比较分析。结果表明:(1)供试三种进化类型大豆种子的 SOD 同工酶酶谱一致,均为7条,其中一条为 Ma-SOD,其余6条为 Cu-Zn-SOD。(2)SOD 活性表现为:野生类型明显高于中间类型,中间类型明显高于栽培类型。(3)随着大豆籽粒百粒重的增大,种胚的 SOD 活性降低。(4)种皮颜色由黑到黄,种皮的 SOD 活性降低。讨论了大豆种子 SOD 活性与 Sofa 亚属内大豆进化的关系。     

低温对不同耐寒力的黄瓜幼苗子叶的各细胞器中NAD~+-苹果酸脱氢酶的影响

NAD~+-MDH在黄瓜子叶中的定位是细胞溶质中占总活性的55～59％,线粒体为38～35％,叶绿体为7％。其同工酶谱亦为细胞溶质中带数最多,全青为5条,粤早3号为4条,线粒体和叶绿体均为1条,品种间无明显差异。黄瓜幼苗随低温胁迫的加剧,伤害逐步加重,子叶电解质渗出率明显增加,NAD~+-MDH活性亦不断下降,其中叶绿体的NAD~+-MDH对低温最敏感,1±1℃处理就能反映品种间耐寒力的差异。叶绿体和线粒体的NAD~+-MDH同工酶对低温的反应与活性变化一致,谱带数没有差异,只是活性降低。细胞溶质部分酶带较多,各条酶带对低温的反应不同。     

小麦和花生叶细胞内超氧物歧化酶(SOD)同工酶的特性和分布

用等电聚焦凝胶电泳方法对小麦、花生叶内超氧物歧化酶同工酶进行了研究,在栽培小麦叶中发现4条 SOD 同工酶谱带。证明位于图谱下方迁移率最大的强单带是叶绿体 SOD,其它3个可能是细胞质 SOD。对野生花生和栽培花生的比较研究结果表明,前者叶中包含3类不同的谱带(文中 A、B 和 C 带)。A 带及 B 带对氰化物敏感,是 Cu-Zn-SOD,C 带不敏感,可能是线粒体 Mn-SOD。栽培花生叶内 SOD 大部集中在叶绿体中,主要是 Cu-Zn-SOD。本文测定了各谱带的 PI 值,并就两类花生叶中 SOD 的不同特性和分布可能对其生物保护功能的影响作了讨论。     

氯苯胁迫对大豆种子萌发的伤害

在实验室人工控制条件下 ,研究了不同浓度 1,2 ,4 三氯苯胁迫对大豆种子萌发和幼苗生长的影响 .结果表明 ,5 0～ 2 0 0 μg·g-1的 1,2 ,4 三氯苯胁迫对大豆种子的发芽率影响甚小 ,但延迟大豆种子的出苗速率 ;30 0 μg·g-1的 1,2 ,3 三氯苯胁迫使种子停止发芽 .在正常条件下 ,大豆种子播种后第 4天其下胚轴超氧化物歧化酶 (SOD)活性达到高峰 ,之后趋于稳定 .不同浓度 1,2 ,4 三氯苯处理使大豆下胚轴SOD活性下降 ,丙二醛 (MDA)、蛋白质含量及下胚轴直径增加 ;幼苗的生长受抑制 ,干重、鲜重有一定程度的下降 ;而鲜重 /干重的比值变化不大 .受害程度随着 1,2 ,4 三氯苯浓度的增加而加重 .初生根比下胚轴对 1,2 ,4 三氯苯胁迫较为敏感 .     

杂交水稻金优63幼苗期SOD和POD特性研究

对杂交水稻金优63幼苗不同时期的根、茎、叶进行SOD同工酶电泳分析,并测定SOD、POD活性。结果表明,自播种后第7天到第13天,幼苗的SOD同工酶在根、茎、叶中有明显的器官特异性,且SOD活性叶 >茎 >根。相同器官不同时期的SOD同工酶电泳谱带条数及SOD活性都有变化,且SOD活性强弱与SOD同工酶电泳谱带中有无Mn-SOD同工酶带有一定的关系。幼苗的POD活性在根、茎、叶中也有明显的器官特异性,茎中POD活性明显高于根和叶,且POD活性变化与SOD活性变化有一定的关系。     

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.     

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     

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.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

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.     

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).     

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.