三江白猪线粒体DNA的多态性

采用22种限制性内切酶分析了三江白猪mtDNA多态性。在60头个体中检出30种限制性态型,归结为7种基因单倍型;其间的差异来自少数限制性位点的突变。单倍型间平均遗传距离为0．35％,群体遗传多态程度为0．044％。三江白猪遗传多样性非常贫乏,说明三江白猪与地方种猪起源于一个共同祖先,在品种形成早期受到创立者效应的制约。     

猪线粒体DNA多态性与中国地方猪种起源分化的关系

用24种限制性内切酶分析了我国21个具代表性地方猪品种、1个引进品种和2个来自中国和越南的野生近缘种mtDNA的RFLP。结果表明:在74个个体中检出的32种限制性态型可归结成7种单倍型,其间的差异主要来源于少数几个限制性位点的点突变;地方猪种4种单倍型间的平均遗传距离为0.143％,遗传多态程度(π值)仅为0.007％,说明遗传多样性非常贫乏,提示中国地方猪种可能起源于一个野猪亚种。     

长江中游水系鲢和草鱼群体mtDNA遗传变异的研究

采用PCR技术进行了长江中游鲢和草鱼四个地理群体的线粒体DNA（mtDNA)限制性片段长度多态性（RFLP）的研究。四个地理群体包括长江中游的湖北嘉鱼和江西瑞昌两个地理群体,长江中游的两大支流江汉和湘江群体。PCR技术扩增出mtDNA ND5-ND6基因,选用10种限制性内切酶对PCR产物进行酶切。从鲢中共检出18种单倍型,在草鱼中没有发现多态现象,只有一种单倍型存在。进一步地证实了长江鲢的遗传多样性比草鱼的要丰富得多,与这两种鱼类在长江现有生物量成反比的反常现象。     

贵州四个山羊品种mtDNA多态性及起源分化

采用１５种限制性内切酶,研究贵州省４个山羊品种共９３只个体的线粒体ＤＮＡ多态性。其中ＢｏｍＨＩ、ＨｉｎｄⅢ和ＳａｌⅠ３种酶的酶切类型存在多态。共检测到１８种限制性态型,归结为３种ｍｔＤＮＡ单倍型。单倍型Ⅰ、Ⅱ在贵州山羊４个品种分布频率较高,分别为７７．４２％和２１．５０％,单倍型Ⅲ分布频率较低（１．０８％）;品种间亲缘关系聚类分析表明白山羊和黑山羊亲缘关系最近,其次为黔林羊,而与小香羊的亲缘关系最     

中国山羊mtDNA D-loop遗传多样性及其起源研究

采用DNA测序技术分析了中国9个山羊品种（板角山羊、成都麻羊、贵州黑山羊、贵州白山羊、黔北麻羊、马头山羊、陕南白山羊、黄淮山羊和雷州山羊）共计128个个体的mtDNA D-loop全序列。结果表明：山羊mtDNA D-loop全序列长度为1212-1213bp,检测到102个变异位点,约占分析位点总数的8．42％,可变位点中转换占99个,颠换2个,1个转换/颠换共存;界定了92种单倍型,有78种为各品种独享单倍型,另外14种为群体内或群体间共享单倍型。9个山羊品种单倍型多样度为0．9333-1．0000,核苷酸多样度为0．7062％-1．8265％,表明中国山羊品种遗传多样性丰富。根据92种mtDNA单倍型构建了中国山羊的NJ分子系统树,聚类表明,中国山羊mtDNA D-loop序列单倍型分为支系A和支系B两大类。支系A包括75种单倍型,代表95个样本,占总数的74．22％;支系B包括17种单倍型,代表33个样本,占总数的25．78％,说明中国山羊存在支系A和支系B两大母系起源。对中国山羊mtDNA D-loop的支系A和支系B进行核苷酸不配对分布曲线分析和Fu的Fs中性检验,分析表明,支系A的分布曲线呈单峰形,Fs值为-24．6491,P值为0．0000,显著偏离中性,表明山羊支系A曾经历群体扩张;支系B呈近似双峰分布,Fs值为-3．3947,P值为0．0980,中性检验差异不显著,表明山羊支系B没有经历群体扩张,群体大小保持相对稳定。山羊支系B可能起源于中国。     

中国主要家鹅品种的遗传分化研究

利用PCR和DNA测序技术扩增了15个中国家鹅品种线粒体DNA控制区部分序列（1042bp）。研究结果表明：伊犁鹅与14个品种间的核苷酸分歧度最高,为3．805％～4．067％;不同品种内核苷酸多样度表现出较大的差异,为0～0．116％。除伊犁鹅外的14个家鹅品种中,豁眼鹅与其他品种间的核苷酸分歧度为0．211％～0．272％,明显高于其他品种间的0～0．094％。中国家鹅品种的遗传分化格局与地理分布有关,豁眼鹅的分歧时间较早,遗传漂变是导致豁眼鹅遗传分化的主要因素（Nm=0．02～0．54）,基因流则是另外13个家鹅品种间遗传分化不明显的主要因素（Nm=12．0～65．33）．     

三大不同品种马mtDNA Cytb基因的PCR-RFLP分析

用BamHⅠ、TaqⅠ、HaeⅢ、RsaⅠ和HincⅡ5种限制性内切酶通过PCR-RFLP技术检测了包括引入品种、培育品种和地方品种的6个类型共256匹马的mtDNA Cytb基因部分序列多态性。用8%非变性聚丙烯酰胺凝胶电泳将酶切产物分离,并用银染法显色。结果BamHⅠ和TaqⅠ表现出多态,5种酶共检测到7种态型,归纳为3种单倍型,以单倍型Ⅰ和Ⅲ为主体单倍型,但通过一个特殊的酶型BamHⅠ-B分析推测所研究的马起源于一个母系祖先。     

中国牦牛线粒体DNA多态性及遗传分化

用２０种限制性内切酶分析了我国５个牦牛群体９０个个体的限制性片段长度多态性,其中ＡｖａＩ,ＡｖａＩＩ、ＢｇｌＩＩ、ＥｃｏＲＩ．ＨｉｎｄＩＩＩ、ＨｐａＩ６个酶切类型具有多态性,共发现５种ｍｔＤＮＡ单倍型,每种单倍型中检出５０－５５个位点,并利用双酶切制定出其物理图谱。我国牦牛群体ｍｔＤＮＡ多样度ＨＴ为０．１０６５,群体内的平均一致性概率为０．８９６６,表明我国牦牛群体ｍｔＤＮＡ多态性较贫乏,群体间的平均净遗传距离Ｐｅｔ为０．０００２０１,群体基因分化系数Ｇｓｔ为０．０２９１,我国牦牛群体ｍｔＤＮＡ变异只有２．９１％来自群体间的差异,群体间的分化程度较低。并根据报道,比较了牦牛和其他家养牛种的ｍｔＤＮＡ遗传分化,估计出牦牛和普通牛、瘤牛的分化时间大约分别在１．１－２．２百万年和１．０１－１．０２百万年之间。     

基于线粒体DNA D-loop区序列的我国灰鹅遗传多样性和起源分析

为了探究我国灰鹅品种的遗传多样性和系统进化,运用DNA测序技术测定了我国13个灰鹅品种mtDNAD-loop区521bp序列。结果表明:这13个灰鹅品种521bpD-loop区序列的T、C、A和G碱基含量分别为23.8%、29.0%、32.3%和15.0%;平均单倍型多样度和核苷酸多样度分别为0.19245和0.00036;13个灰鹅种间变异大于种内变异,且均未出现群体扩张现象;共享单倍型和系统进化树分析表明,伊犁鹅起源于灰雁(Anser anser),其余12个灰鹅品种起源于鸿雁(A.cygnoides)。     

中国大陆部分地区Drosophila immigrans果蝇种群中mtDNA的遗传多态性研究

选用14种限制性内切酶对分布在中国大陆部分地区的Drosophilaimmigrans果蝇种群的线粒体DNA（mtDNA）限制性片段长度多态性（RFLP）进行了分析。在6个地理种群的46个单雌系中仅检测到11种限制性类型。表征种群内均一程度的I值平均为0．833。衡量种群间等同程度的J值平均为0．797。在整个种群中只有16．8％（Gst）的变异是由种群间变异所引起的。说明分布在中国大陆部分地区的D．immigrans果蝇的遗传组成均一程度高,遗传多态程度低,遗传变异贫乏。由UPG法分析6个种群的净遗传距离,显示了分布在秦岭华阳种群（HY）的特殊性。推测D．immigrans果蝇扩散到云南的高海拔地区可能是较晚发生的事件。并推测中国大陆的D．immigrans种群比分布在中国台湾,日本的种群原始。     

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.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV