梨黑星菌粗毒素对抗病和感病梨离体叶片生理特性的影响

以不同抗病性梨品种为材料,研究了梨黑星菌粗毒素对梨离体叶片的过氧化物酶(POD)活性、苯丙氨酸解氨酶(PAL)活性、丙二醛(MDA)含量、细胞膜相对透性以及叶绿素含量变化的影响.研究表明,毒素接种后抗病和感病品种叶片的POD和PAL活性、MDA含量和相对电导率均呈上升趋势,其间会有1个或2个峰值出现,且抗病品种叶片的POD和PAL活性高于感病品种,而细胞内MDA含量和相对电导率增加比率低于感病品种;同时,毒素使梨离体叶片的叶绿素、类胡萝卜素含量下降,且感病品种的下降幅度大于抗病品种.总之,梨离体叶片POD和PAL的活性变化与梨品种抗病性呈正相关,叶片MDA含量和相对电导率变化与梨品种抗病性呈负相关,抗病品种离体叶片对毒素的毒害有更强的抵抗力.     

不同抗性猕猴桃品种感染溃疡病前后几种保护酶活性变化

研究了不同猕猴桃品种展叶孕蕾期自然感染溃疡病菌前后一年生枝条、叶片内过氧化物酶(POD)、多酚氧化酶(PPO)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、苯丙氨酸解氨酶(PAL)酶活性的变化情况.结果表明:感染溃疡病菌前后,抗病品种和感病品种枝条及成叶中防御酶系活性变化规律存在一定的差异.品种未受溃疡病菌感染时,一年生枝条、叶片中的POD、PPO、SOD、CAT酶活性抗病品种的酶活性均低于感病品种.品种自然感染溃疡病菌后,一年生枝条、叶片POD、PPO、SOD、CAT、PAL酶活性均升高,且酶活性的增加幅度是抗病品种中酶活提高倍数高于感病品种.而且这种增量在不同保护酶类以及不同组织部位是有差异的.     

小麦白粉病菌对小麦幼苗光合生理特性的影响

为探讨小麦白粉病菌对不同抗性小麦品种幼苗光合生理特性的影响,本研究采用白粉病强致病力生理小种E09感染高抗小麦白粉病品种青春38、高感小麦白粉病品种龙麦33幼苗,研究接菌后0 d、1 d、2 d、4 d、6 d、8 d、10 d小麦叶片总叶绿素含量、光合速率(Pn)、叶片可溶性蛋白、叶片细胞内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性的变化。研究数据表明,接种小麦白粉病菌后,两小麦品种青春38和龙麦33的体内相对叶绿素含量、光合速率及可溶性蛋白含量均不同程度的降低,且感病品种龙麦33降低幅度较抗病品种青春38高。接菌后,两个品种的相对SOD、POD及CAT活性均表现为先升高后降低的变化趋势,相对SOD活性表现为感病品种龙麦33的峰值高于抗病品种青春38的峰值;相对POD活性则是抗病品种青春38的增加幅度极显著高于感病品种龙麦33的增加幅度;相对CAT活性则表现为两品种出现峰值的时间不同,但峰值幅度差异不显著。     

禾谷镰刀菌粗毒素对不同小麦品种幼苗MDA含量和SOD、PAL活性的影响

用禾谷镰刀菌粗毒素对赤霉病抗性不同的6个小麦品种(系)幼苗进行处理,在1h~10d内测定各品种(系)的MDA含量、SOD及PAL活性增率的变化.结果显示:禾谷镰刀菌粗毒素处理后,抗病和中抗品种(系)幼苗的MDA含量增率低于感病品种(系),且增加速度慢;抗病和中抗品种(系)幼苗的SOD活性在胁迫1h后迅速升高,其活性增率高于感病品种(系);抗、感品种(系)PAL活性均升高,但抗病品种(系)PAL活性增加快,且活性增率高于感病品种(系).研究表明,小麦幼苗的SOD、PAL活性增率与品种抗病性呈正相关,MDA含量增率与品种抗病性呈负相关.     

桃色顶孢霉代谢产物对绿豆白粉病的防治作用

应用桃色顶孢霉发酵液中蛋白粗提物、三唑酮处理感病绿豆叶片和植株,比较分析病斑变化和综合病情指数,并测定不同处理植株新生叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性及丙二醛(MDA)含量,探究桃色顶孢霉发酵液粗提蛋白对绿豆白粉病的影响。结果表明,喷施粗提蛋白的感病植株叶片的病斑变化明显,且新生叶片鲜绿,无白粉病菌侵染症状。与喷施无菌水的对照相比,喷施粗提蛋白的感白粉病绿豆植株叶片CAT酶活性提高了71.70%,差异显著,而POD酶活性降低了8.45%,且叶片MDA含量降低了29.81%。试验结果证实了桃色顶孢霉发酵液的蛋白粗提物对绿豆白粉病具有一定的防治效果,并能影响到植物相关抗逆酶的活性。     

玉米大斑病菌HT-毒素与玉米细胞的膜脂过氧化研究*

以土培玉米幼苗为材料 ,通过测定玉米大斑病菌HT 毒素处理后玉米叶片细胞膜透性和细胞内丙二醛 (MDA)含量变化及其与细胞内过氧化物歧化酶 (SOD)、过氧化物酶(POD)活性之间的关系来研究玉米细胞膜脂过氧化的程度。结果表明 ,HT 毒素胁迫后 ,亲和组合MDA含量上升 ,POD活性受到刺激 ,SOD活性受抑制较强 ;非亲和组合POD活性受到抑制 ,SOD活性受抑制较弱。HT 毒素对玉米叶片细胞膜有强烈的破坏作用 ,而且这种作用与毒素的浓度和毒素处理的时间呈正相关。试验结果初步推测在抗、感玉米的细胞膜上     

外源H2O2胁迫对大蒜试管苗玻璃化的影响

以大蒜品种‘二水早’为材料,研究不同浓度外源H2O2胁迫对大蒜试管苗的玻璃化发生及生理生化变化的影响.结果表明,在不同浓度外源H2O2处理下,大蒜玻璃化试管苗百分率、组织含水量、MDA含量、电解质渗透率、SOD和POD活性均高于对照,且随H2O2浓度的增加而升高,叶绿素含量则表现相反的趋势;在同一H2O2浓度下,大蒜玻璃化试管苗的组织含水量、MDA含量、电解质渗透率、SOD、POD和CAT活性均显著高于大蒜正常试管苗,叶绿素含量低于正常试管苗.研究发现,外源H2O2胁迫对大蒜试管苗玻璃化有促进作用.     

几种同工酶与猕猴桃品种对溃疡病抗性关系的研究

应用聚丙烯酰胺凝胶电泳、同工酶分析技术分别研究了猕猴桃植株体内过氧化物酶(POD)、多酚氧化酶(PPO)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、酯酶(EST)同工酶谱带的变化,结果表明:自然感染溃疡病前后,此6种同工酶谱带特征在不同抗感品种中表现出一定的差异.未感染溃疡病菌前,抗(感)品系枝条、叶片POD同工酶均有2条酶带,PPO同工酶有3条酶带,但感病品种酶带颜色深且粗,而抗病品种酶带颜色浅且细,叶片酶带颜色深于枝条;SOD、CAT同工酶谱带均为1条,Rf值分别为0.38、0.28,感性品种较抗耐品种谱带亮度高活性强;自然发病后,抗(感)品系POD、PPO同工酶谱带数都增加,分别为4、3条和5、4条,且抗病品种新酶带出现较感病品种早且酶带粗颜色深活性强,感病品系虽也有新酶带出现,但酶带少活性弱,抗病品系枝条、叶片POD、PPO同工酶新谱带的Rf值分别为0.63、0.67和0.85、0.87;抗感病品种SOD、CAT同工酶都被诱导产生了1条新的同工酶谱带,Rf分别为0.32和0.27,新酶带现色时间迟,且酶带颜色浅活性弱,但抗耐品种较感性品种谱带亮且活性强;EST同工酶于自然发病前后变化不大,与抗病性关系不很明显.     

硅和白粉菌诱导接种对黄瓜幼苗白粉病抗性影响的研究

研究了硅酸盐和诱导接种白粉菌对黄瓜活性氧代谢、SiO2含量和抗病性的影响．结果表明,诱导接种能使叶片的超氧自由基(O2^-)产生速率、H2O2和丙二醛(MDA)含量升高,加硅接种处理的O2^-产生速率、H202和MDA含量明显低于不加硅接种处理．诱导接种能使叶片的过氧化氢酶(CAT)、过氧化物酶(POD)活性升高,超氧化物歧化酶(SOD)活性降低．加硅接种处理植株叶片的CAT、POD和SOD活性明显高于不加硅接种处理．诱导接种提高叶片的抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量,加硅处理的AsA含量明显低于不加硅处理,GSH含量高于不加硅处理．无论接种与否,加硅处理的SiO2含量显著高于不加硅处理,病情指数明显低于不加硅处理．     

不同苹果品种对褐斑病抗性的鉴定及抗性生理研究

对42个苹果栽培品种叶片褐斑病进行了田间发病状况调查与抗性鉴定,分析了叶片气孔密度和大小与抗病性之间的关系,同时研究了不同抗性品种离体叶片接种病原菌后超氧化物歧化酶（SOD）、多酚氧化酶（vPo）、过氧化物酶（POD）、苯丙氨酸解氨酶（PAL）活性和木质素含量的差异变化。依照抗性分级标准,供试材料中抗病品种有14个（其中高抗品种2个）,感病品种有28个（其中高感品种7个）;叶片气孔密度与病情指数之间存在显著正相关,相关系数r=0．683;叶片接种后,诱导了4种酶活性和木质素含量的升高,抗病和感病品种的SOD和PP0活性无显著差异,而抗病品种的POD和PAL活性以及木质素含量显著高于感病品种。苹果叶片的气孔密度、POD和PAL的活性以及木质素含量与褐斑病抗性有关。     

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).