稻瘟菌无毒基因研究进展

无毒基因编码的产物激发病原物与植物特异性相互作用。水稻与稻瘟菌之间的特异互作符合“基因对基因”关系。从研究稻瘟菌无毒基因的意义、已鉴定和克隆的稻瘟菌无毒基因、稻瘟菌无毒基因与其抗病基因的互作特点等几个方面,对稻瘟菌无毒基因研究进展作了简要评述 。     

紫甘薯花色苷色素的抑菌机理研究

<正>人类和动物的食品安全有赖于生产的各个环节,使用无污染、无残留、无毒副作用的食品添加剂是解决食品中药物残留的关键。     

藻类连续培养体系的构建与优化及其在产毒和无毒微囊藻竞争中的应用

利用发酵罐加装外置环形光源构建藻类连续培养系统, 以产毒微囊藻PCC 7806及其无毒突变株PCC 7806 mcyB–为培养材料, 通过对补料时间、接种密度和稀释率参数的优化, 获得最优培养条件, 并应用于产毒与无毒微囊藻的竞争实验中。通过优化得到连续培养的最优培养条件: 补料时间为第4天, 起始接种密度为4×106 cells/mL, 稀释率为0.15/d。在连续培养下, 光照为35 μmol/(m2·s)时, 以1﹕1的起始比例接种产毒与无毒微囊藻, 二者间的竞争会达到平衡, 并以无毒微囊藻占据优势, 且两者以不同的优势度长时间维持不变。在此基础上, 开展了不同光强对产毒与无毒微囊藻竞争影响的实验, 结果表明, 光强为35和80 μmol/(m2·s)时, 无毒株在连续培养中占据优势; 而光强为5和15 μmol/(m2·s)时, 无毒和产毒微囊藻维持起始接种比例不变。研究通过优化连续培养条件为室内藻类竞争实验提供了更为适宜的培养模式。     

稻瘟菌无毒基因的分子检测及其指纹类型分析

针对稻瘟菌中Avr-Pita与AvrPiz-t两个无毒基因,设计特异性引物,利用PCR方法对吉林省103株稻瘟菌菌株进行分子检测,并结合AVR-Pib、AVR-C039、PWL2和ACE1 4个无毒基因在其中85个菌株中的分布情况,绘制出基于这6个无毒基因的指纹类型.结果表明,Avr-Pita基因和AvrPiz-t基因在吉林省稻瘟菌中的分布频率分别为86.41%和62.14%;建立的指纹类型显示,85株稻瘟菌分布于9种类型中,其中类型1为主要类型,其分布频率为40.00%:根据30个已知生理小种的菌株在指纹类型中的分布情况,初步发现类型7与吉林省优势生理小种ZE1可能存在对应关系,并应用于稻瘟菌优势生理小种的特异性分子检测;其他指纹类型与中国生理小种并无明显对应关系.明确了无毒基因Avr-Pita与AvrPiz-t在吉林省稻瘟菌中的分布情况,构建了无毒基因的指纹类型,为水稻抗瘟育种和稻瘟菌优势小种的分子监测提供理论依据.     

引起产科新生儿腹演暴发的轮状病毒株VP4 VP7编码基因与其毒力关系的探讨

克隆并测定了引起产科新生儿腹泻暴发的Ｐ２「６」、Ｇ４型轮状病毒（ＢＮ株）ＶＰ４的ＶＰ８片段和ＶＰ７编码基因的核苷酸序列,并据此推导出其氨基酸序列。与相应标准株和地方株９包括有毒株和无毒株）比较的结果表明,所测ＶＰ８序列与相同型另（Ｐ２「６」）的标准株Ｍ３７（无毒株）和ＳＴ３（无毒株）、地方株Ｎ１６（无毒株）和ＶＥ７１５６（有毒株）之间的同源性为９２．８％￣９８．６％,胰酶作用位点各毒株间相同;位于     

植物病原物无毒基因及其功能

植物抗病基因与病原物无毒基因产物间直接或间接相互作用导致产生的基因对基因抗性是植物抗病性的重要形式。无毒基因已在多种植物病原物 ,包括真菌、细菌、病毒和卵菌等中得到克隆。绝大多数已克隆无毒基因之间 ,及其与已知蛋白之间 ,均无显著序列同源性。然而 ,多数已克隆植物抗病基因有较高序列一致性 ,产物往往具有相似的结构域。由序列一致性很高的抗病基因产物与没有明显序列同源性的无毒基因产物相互作用 ,介导产生的过敏性细胞坏死和抗病性 ,在产生速度、强度和组织特异性等方面均可能有显著差异。无毒基因具有双重功能 :在含互补抗病基因植物中表现无毒效应 ,而在不含互补抗病基因植物中显示小种、菌株、致病型、或种特异性毒性效应     

鲤科鱼类急性胆汁中毒的动物实验研究

中国传统医学典籍《本草纲目》记载,各种鱼胆“无毒”,且有不同疗效,如“青鱼胆苦寒,无毒,消赤目肿痛,吐喉痹痰涎,疗恶疮”;“鲤鱼胆苦寒、无毒,主治目热赤痛,青盲,明目,久服强悍,益志气。点眼,治赤肿翳;滴耳,治聋;治大人阳痿”。唐《千金方》还记述服鲤鱼胆治阳痿、赤眼和百日咳;加上各种中药大辞典、地方药物志相互抄袭吞服鱼胆治病的偏方,误导群众深信鱼胆具有“清热解毒”、“明目”、“治咳平喘”以及降压、镇嗽、化痰等药效。遇到上述疾患,即吞服鱼胆以治病,也许是造成现今我国部分地区民间吞胆治病悲剧不断发生…     

植物抗病基因与病原菌无毒基因互作的分子基础

近10年来,大量的植物抗病基因和病原菌无毒基因被克隆,抗病基因和无毒基因的结构、功能及其互作关系的研究也取得重大进展。通过介绍抗病基因与无毒基因互作的两种模式,从抗病基因与病原菌无毒基因互作角度探讨了抗病基因在植物抗病育种和农作物生产中直用的问题,提出抗细菌和真菌单基因转化很难赋予农作物切实抗性。     

黄曲霉毒素B1抗独特型抗体的制备和应用研究II.抗独特型抗体应用

以抗独特型抗体(anti-idiotypeantibody,Ab2)的酶切片段Fab2替代黄曲霉毒素B1(AFB1)建立一种不需要使用AFB1的无毒酶联免疫吸附(Enzyme-LinkedImmunosorbentAssay,ELISA)试剂盒,研究该试剂盒特异性、稳定性和AFB1的加标回收,并将该试剂盒用于农产品和饲料中AFB1的检测。结果表明,该试剂盒具有和常规ELISA试剂盒一样的特异性和加标回收能力,无毒试剂盒和常规试剂盒一样都可以用于农产品和饲料中AFB1的检测,并且两种试剂盒的检测结果并无显著差异,无毒ELISA试剂盒在适当处理后,40C放置3个月和-200C放置5个月,以间接非竞争ELISA测定的吸光值分别是起始时的85%和87%。     

稻瘟菌无毒基因研究进展

稻瘟菌是引起水稻稻瘟病的病原物。水稻与稻瘟菌间存在广泛而特异的相互作用,是研究寄主与病原物互作的重要模式系统。本文对稻瘟菌与水稻互作最重要的激发子―无毒基因的研究现状进行了概括,讨论了无毒基因的定位、克隆方法以及已克隆无毒基因的功能及进化研究,同时对今后无毒基因研究的重要方向进行了探讨,为深入理解无毒基因的功能及与水稻可能的互作关系奠定了基础。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.