基因互作形式判定的代数方法(Ⅱ)

2基因互作形式的判定法则（上续本刊1994第5期第57页）基因互作是在不同位点之间进行的,并不影响同一位点上等位基因的显隐性,因此,我们可以在定理2的基础上作进一步的讨论．不失一般性,我们只讨论两个位点的情况,今后记称为单位点的分离比．由定理1知：当为叙述方便,下文中,将由于基因互作而出现的表型简以互作形式的表型称呼．例如“上位作用表型”,“重叠作用表型”等,将基因型中仅有一种显性基因而表现的表型简称为“单显表型”,同时,为缩小篇幅,只证法则1,其它同理．法则1亲代两非等位基因存在上位作用的充要条件是子代的…     

HIV-1感染的共受体

早在1984年就已发现人免疫缺陷病毒一I型（HIV－l）感染细胞是通过与细胞表面受体CDe结合而进行的,但两年后又发现表达CDe的非人类细胞不能被IlfV－l感染,因此有人认为仅有CDe作为H］V－l的受体是不够的,还必须有人类细胞特异表达的某种辅助因子。最近,一些与CDe偶联的HIV则共受体已被陆续鉴定,它们均为趋化因子（chemokjnes受体家族的成员,也正是H］V－l感染所必需的辅助因子。互作为HIV—且共受体的趋化因子受体CXCR4是第一个被发现具有I］：IV－l共受体作用的蛋白质I’］,最初称为融合素（fusin）、LESTR等。最近…     

巴西橡胶树HbSIP2互作蛋白的筛选和鉴定

可溶性无机焦磷酸酶在天然橡胶生物合成中具有重要的调控作用,HbSIP2是胶乳中关键的可溶性无机焦磷酸酶基因。为了深入了解HbSIP2调控橡胶生物合成的机理,本研究对HbSIP2互作蛋白进行了筛选和鉴定。结果表明:诱饵载体p GBKT7-Hb SIP2无自激活活性,且对酵母无毒性作用,可以用于酵母文库筛选。将诱饵载体与橡胶树胶乳cDNA文库进行杂交,初步筛选获得20个与HbSIP2互作的蛋白。进一步通过双分子荧光互补实验证实,Hb SIP2能够与橡胶延伸因子发生蛋白互作。本研究结果为HbSIP2调控橡胶生物合成的机理研究提供了重要的理论依据。     

基因互作与基因型判定的代数方法

如何根据子代的表型判断基因互作的形式以及确定亲代的基因型，是遗传学上重要的也是困难的问题．本文在完全显性及不考虑非遗传因素的条件下，利用文[1]给出了解决上述问题的代数方法．在应用上，要比以往的方法更为优越．     

玉米酵母双杂交cDNA文库的构建及ZmCEN互作蛋白的筛选

为阐明玉米中心蛋白(ZmCEN)的生物学功能,采用酵母双杂交技术对其互作蛋白进行研究。提取玉米(Zea mays L.)自交系‘郑58’幼苗的总RNA,利用SMART技术反转录合成ds cDNA,构建以pGBKT7为载体的酵母双杂交cDNA文库;依据ZmCEN基因的CDS序列设计引物,构建重组诱饵载体(pGBKT7-ZmCEN)转化酵母菌株Y2HGold,检测诱饵载体的毒性与自激活能力后,筛选与玉米中心蛋白(ZmCEN)互作的猎物蛋白。将筛选的互作蛋白NAC67和TONNEAU1b(TON1b)再次验证相互作用,并选取互作蛋白TON1b,采用BiFC实验分别构建ZmCEN-pSPYNE和TON1b-pSPYCE BiFC半分子重组载体,转化拟南芥原生质体,进一步验证它们在细胞内的互作;并利用Uniprot和KEGG在线网站对互作蛋白进行gene ontology(GO)注释分析。结果表明:玉米全株幼苗的cDNA文库库容量达到2.56×107 CFU,文库滴度5.36×108 CFU/mL,符合建库要求。经检测诱饵载体无毒性也无自激活功能,所筛选的cDNA文库经测序和Blast比对分析以及共转验证,最终得到28个与诱饵蛋白ZmCEN互作的蛋白质。GO注释显示互作蛋白参与的生物过程有21种。BiFC结果显示,蛋白TON1b与ZmCEN在拟南芥原生质体细胞内互作而形成互补,从而产生黄色荧光,进一步证实了两者存在互作关系。酵母双杂交系统cDNA文库的成功构建与筛选,为进一步研究玉米ZmCEN及其与互作蛋白的作用机制奠定了基础。     

利用各世代小区平均数的加权最小二乘法在玉米数量性状遗传分析上的应用

本文根据作者在参考文献[3]所提出的利用各世代小区平均数估计遗传参数的加权最小二乘法对玉米穗粒重的遗传特性进行了分析。结果表明:(1)在本次试验中,可用加性-显性-二基因互作模型来描述玉米穗粒重的遗传特性;其加性效应[d]、加性效应与显性效应的互作[j]在α=0.01水平上显著,显性效应[h]、显性效应与显性效应的互作[l]在α=0.10水平上显著,加性效应与加性效应的互作[i]不显著;[d]与[h]的差异在α=0.10水平上不显著,但([d] [h])与([i] [j] [l])在α=0.05水平上显著;(2)与利用6个世代平均数相比,利用8个世代小区平均数的加权最小二乘法既节约、又灵敏。     

猪δ冠状病毒核衣壳蛋白互作的蛋白鉴定及分析

初步筛选与鉴定PDCoV N蛋白的宿主互作蛋白.利用免疫共沉淀(Co-immunoprecipitation,CO-IP)和LC-MS/MS质谱技术筛选出PDCoVN蛋白的宿主互作蛋白,并进行生物信息学分析,再利用免疫共沉淀进行鉴定.通过免疫共沉淀产物的SDS-PAGE分析发现在40 kD和100 kD左右有明显的差异蛋白条带,通过质谱筛选到了68个与PDCoVN蛋白互作的宿主蛋白,并做了GO、COG和KEGG注释,挑选出2个候选互作蛋白,经过免疫共沉淀验证,PDCoVN蛋白与TUBB2B存在互作关系.该研究为进一步探索PDCoV N蛋白在病毒感染细胞时的作用提供了新方向.     

稻瘟菌糖蛋白激发子诱导的水稻叶片膜脂过氧化及过敏性反应

将稻瘟菌细胞壁来源的专化性糖蛋白激发子接种于一套水稻抗稻瘟病近等基因系后,非亲和性互作水稻超氧阴离子(O-.2)积累在互作早期明显高于亲和性互作水稻;超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性均趋于下降,不同亲和性互作水稻间的差异不明显;脂氧合酶(LOX)活性在水稻/激发子非亲和互作早期增加明显、速度快;这些指标的变化进而导致非亲和性互作水稻的膜脂过氧化,其相对电导率及丙二醛(MDA)含量的高峰期和强度也明显早于和高于亲和性互作水稻.非亲和性互作水稻过氧化物酶(POD)活性在互作早期明显高于亲和性互作水稻,可能与其参与其它抗性有关.研究同时表明,激发子可专化性诱导完全和高度非亲和性互作水稻的过敏性坏死反应;而中度非亲和性互作和亲和性互作水稻则未发生过敏性(HR)坏死反应.这些结果表明,膜脂过氧化和HR反应的发生是激发子诱导水稻抗性的主要生理机制之一.     

利用酵母双杂交筛选木薯果胶甲酯酶抑制因子MePMEI1的互作蛋白

果胶甲酯酶抑制因子(PMEI)在植物抗逆过程中具有重要作用.为了探究木薯MePMEI1的生物学功能及其在蛋白互作网络中的作用,本研究通过构建诱饵载体pGBKT7-MePMEI1,通过酵母双杂交方法从木薯cDNA文库中筛选MePMEI1的互作蛋白.结果表明,酵母双杂交共筛选出57个阳性克隆,阳性率约为32.6％,测序鉴定出37种含完整开放阅读框(ORF)的候选互作蛋白,包括非特异性丝氨酸/苏氨酸蛋白激酶/苏氨酸特异性蛋白激酶、叶绿素a/b结合蛋白、电压依赖性阴离子通道蛋白(VDAC2)、乙二醛酶Glyox-alase-2、氮素调节蛋白、木糖葡萄糖转移酶(TCH4)等,并通过回转验证检验其蛋白互作的真实性.验证结果表明MePMEI1与VDAC2、Glyoxalase-2蛋白具有相互作用.这进一步补充了其蛋白互作网络,为探究MeP-MEI1蛋白的互作网络提供新的依据.     

L-periaxin与DRP2蛋白互作的精细分析

轴周蛋白L-periaxin作为外周神经系统中特异表达的骨架蛋白之一,在髓鞘成熟与维护过程中发挥重要作用.肌营养不良相关蛋白2(DRP2)是目前报道与L-periaxin存在明确相互作用的唯一蛋白,但两蛋白精细的互作区域及互作的分子机制仍不清楚.本研究通过双分子荧光互补、免疫共沉淀、GST pull-down、荧光光谱、细胞定位等技术,进一步揭示了periaxin蛋白的核定位信号NLS结构域上3段不同的亚结构域中,NLS1只参与periaxin蛋白的核定位,NLS2和NLS3参与DRP2蛋白的互作;DRP2蛋白中spectrin like2和WW结构域参与和L-periaxin蛋白的互作.L-periaxin与DRP2互作区域的精细定位,为进一步在蛋白水平探讨L-periaxin与脱髓鞘型腓骨肌萎缩症4F亚型的发生机制之间的关系提供参考.     

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.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.