Development of in vitro fertilized embryos of the polyclad flatworm,Hoploplana inquilina,following blastomere separation and deletion

Summary After in vitro fertilization of naked eggs of the polyclad turbellarian, Hoploplana inquilina, both cell separation experiments and deletions of specific blastomeres are possible. With these techniques one can analyze the developmental potential of isolated blastomeres and determine if the embryonic axes have been established at the four-cell stage in this primitive, equally-cleaving spiralian embryo. Two-cell separation experiments with development of both halves resulted in pairs of larvae 1) neither of which had an eye (29%), 2) both of which had one eye (19%), and 3) one of which was eyeless and the other was one-eyed (43%). Deletion of one blastomere at the four-cell stage resulted in 68% one-eyed, 28% two-eyed and 3% eyeless larvae. The one-eyed larvae were asymmetric with respect to eye position with more having right than left eyes. Abnormal or missing ventrolateral lobes occurred with deletion of any of the macromeres at four cells but were significantly more common when A or C rather than B or D was deleted. The experiments support the hypothesis that eye development is a consequence of cytoplasmic localization of both a specific eye precursor and an inducer which segregate independently of cleavage planes, and indicate that the embryonic axes have been determined at the four-cell stage.     

广东省烟草花叶病病原病毒的鉴定

烟草花叶病是广东省产烟区的主要病害之一。我们在南雄等八个县进行调查,1983年至1984年的一般发病率为2～20％。根据血清学反应、病毒粒体形态、鉴别寄主反应及寄主范围、媒介昆虫种类、物理性质、交互保护反应等各项检验结果,鉴定广东省烟草花叶病病原是:三个黄瓜花叶病毒可能株系(普通株系CMV-C,烟草坏死株系CMV-TN,烟草黄色坏死株系(CMV-TYN),烟草花叶病毒(TMV),马铃薯病毒Y(PVY),烟草脉带花叶病毒(TVBMV)和烟草褪绿斑驳病毒(TCMV)(暂定)。     

Symmetry and Asymmetry Models for Rectangular Tables

The models of complete, quasi and conditional symmetry as well as marginal homogeneity and diagonal asymmetry, applicable to square contingency tables are extended to non-square ones. Several properties of the models are investigated and estimation and test theory is presented. The utility of the new proposed models is discussed and illustrated by reanalyzing classical data sets.     

小麦土传病毒在感病小麦细胞中的分布及小麦梭条斑花叶病毒RNA组分

四川雅安、陕西长安的土传小麦病毒病由小麦梭条斑花叶病毒(WSSMV)引起,而浙江安吉、新昌、江苏宜兴的病害则由WSSMV和土传小麦花叶病毒(SBWMV)所致。WSSMV和SBWMV可以同时复合侵染同一株小麦,但在病细胞中二者彼此独立分布。我国WSSMV RNA有2个基因组,分子量分别为2.6×10~6和1.5×10~6,与日本小麦黄花叶病毒(WYMV)一致。     

Subunit symmetry of tetrameric phosphorylase a

Native crystallographic data of tetrameric phosphorylase a crystals, space group P2₁; have been collected photographically to 3 å resolution. These data have been used in Patterson search methods in reciprocal and real space.The tetramers were found to exhibit molecular 222 symmetry. The cross vector between the centres of the two symmetry related tetramers in the unit cell was determined by two different translation function methods.On the basis of these rotation and translation function results a model for the arrangement of monomers within the tetramer and of tetramers in the unit cell is proposed.The 222 symmetry of the tetrameric molecule is found only when high resolution diffraction data are included (i.e. higher than 6 å). At lower resolution other symmetries dominate.Calculations with the proposed model have shown that these spurious symmetries result from the nonspecific overlap of protein-protein and solvent-solvent cross vectors.These results emphasize the importance of high resolution data when noncrystallographic symmetry of globular proteins is studied.Extract from Dissertation, Technische UniversitÄt München.     

Association of a potyvirus with mosaic disease of gherkin (<Emphasis Type="Italic">Cucumis anguria</Emphasis> L.) in India

A virus associated with severe mosaic disease of gherkin (Cucumis anguria L.) in south India was identified. The infected plants showed mosaic, vein banding, blistering on malformed leaves and fruits. Host range, transmission, serological and electron microscopic studies were carried out to identify the virus. The virus was readily transmitted by Sap inoculation and by aphids in a non-persistent manner. The host range of the virus was mainly limited to cucurbitaceous and chenopodium species. The virus showed positive serological relationships with members of potyvirus genus but not with cucumo, ilar and taspoviruses. Electron microscopy of leaf dip preparation of infected leaves revealed long flexuous filamentous virus particles measuring 750 × 12 nm. On the basis of symptomotology, host range, transmission, serology and particle morphology the virus associated with mosaic disease of gherkin might be the member of potyvirus genus.     

Affine extensions of the icosahedral group with applications to the three-dimensional organisation of simple viruses

Since the seminal work of Caspar and Klug on the structure of the protein containers that encapsulate and hence protect the viral genome, it has been recognised that icosahedral symmetry is crucial for the structural organisation of viruses. In particular, icosahedral symmetry has been invoked in order to predict the surface structures of viral capsids in terms of tessellations or tilings that schematically encode the locations of the protein subunits in the capsids. Whilst this approach is capable of predicting the relative locations of the proteins in the capsids, information on their tertiary structures and the organisation of the viral genome within the capsid are inaccessible. We develop here a mathematical framework based on affine extensions of the icosahedral group that allows us to describe those aspects of the three-dimensional structure of simple viruses. This approach complements Caspar-Klug theory and provides details on virus structure that have not been accessible with previous methods, implying that icosahedral symmetry is more important for virus architecture than previously appreciated.      

浙江榨菜病毒病病原鉴定

从浙江桐乡和海宁的花叶或叶片皱缩、植株矮化的榨菜(Brassica juncea Coss)上分离毒源,摩擦接种5种鉴别寄主,在鉴别寄主上都出现不同症状;间接酶联免疫吸附法(In-direct ELISA)检测,芜菁花叶病毒(Turnip mosaic virus,TuMV)的检出率为87.5％,黄瓜花叶病毒(Cucumber mosaic virus,CMV)为73.08％,两者复合侵染率为65.38％,所有的样本都没有检测到烟草花叶病毒(Tobacco mosaic virus,TMV)     

Analysis of a hybrid zone between subspecies of the tiger salamander (Ambystoma tigrinum) in central New Mexico,USA

We analyzed patterns of variation in polymorphic loci across a contact zone between two subspecies of tiger salamander, Ambystoma tigrinum nebulosum and A. t. mavortium, in west-central New Mexico. We found no fixed differences between A. t. mavortium and A. t. nebulosum. Allele frequencies across the contact zone did not vary concordantly among loci, but frequencies at two loci varied with elevation. Gene flow extends through the contact zone from A. t. mavortium into A. t. nebulosum, but not conversely. A. t. mavortium and A. t. nebulosum have no obvious impediments to gene flow within this contact zone, but some populations differ in time of reproduction. The contact zone comprises a variety of habitats, approximating typical A. t. mavortium or A. t. nebulosum habitats. There is an irregular pattern of differences in allelic frequencies among populations that covaries with habitats and is consistent with a model of a mosaic contact zone. Our results contrast with those of a study along the Front Range in Colorado, where allelic composition at some loci changed abruptly across a narrow zone of contact. These contrasting results suggest that the dynamics shaping the contact zone between the same taxa may differ. Absence of a similar pattern of genetic differentiation between A. t. mavortium and A. t. nebulosum in New Mexico and in Colorado suggests a complex set of evolutionary interactions along the eastern front of the Rocky Mountain axis.     

谈“教学型高校”加大科研力度的必要性

‘教学型’高校教师的主要工作是教学,科研工作处于时断时续的状态。针对以上现实,本文指出了“教学型高校”加大科研力度的必要性,并就目前的科研现实提出切实可行的改进措施。①教学与科研不是独立的两个方面,而是相互促进的一个整体,加大‘教学型’高校的科研力度可以达到教学、科研的互利双赢。科研应该逐渐成为‘教学型高校’教师的重要工作内容。②重视科研也是重视教学,提高教学质量以及围绕教学进行的评估、教改等各项举措,也应该从加大科研力度的角度进行：教师有了科研工作,自然需要学生参与;而学生加入到教师的科研活动,不仅是对学生动手能力、创新意识的最好培养,更将明显提高学生学习理论知识的积极性,提高听课效率。③改善‘教学型高校’科研工作的现状,可从设立研究型教师岗位和减少行政指令性活动等方面入手。     

The Silk Road, Marco Polo, a Bible and its proteome: a detective story

Around the end of XIII century (at the time of young Marco Polo's first trip to China at the court of Khubilai Khan in Khan Baliq) a pocket Bible was delivered by a Franciscan friar to the Mogul Emperor, in the framework of the evangelization program of the Far East. Four centuries later, in 1685, this Bible was rediscovered by the Jesuit Philippe Couplet in the house of a rich Chinese in Nanchin and donated to Cosimo III, Grand Duke of Tuscany. This Bible was recently "unearthed" in the Biblioteca Medicea Laurenziana in Florence, wrapped up in a precious yellow silk cloth, in a rather ruined state. After two years of restoration, the Bible will return to China in 2012 for a celebration of its >700years of life and of its remarkable return trip on the Silk Road. On account of the thinness of the parchment (barely 80μm thickness, the size of each foil being 16.5×11cm) it was widely held that the pages were produced from foetal lambskins. On tiny fragments of the margins of a foil, after several unsuccessful attempts at digesting the vellum, we were able to obtain a tryptic peptide mixture, which, upon mass spectrometry analysis, yielded the identity of 8 unique proteins, belonging to the genus Bos taurus, thus confirming the origin of the vellum from calfskins rather than from foetal lambskins. Our results prove that it is possible to obtain reliable protein extraction and IDs from ancient parchment documents.     

Mosaicism in CRISPR/Cas9-mediated genome editing

The CRISPR/Cas9 system is a rapid, simple, and often extremely efficient gene editing method. This method has been used in a variety of organisms and cell types over the past several years. However, using this technology for generating gene-edited animals involves a number of obstacles. One such obstacle is mosaicism, which is common in founder animals. This is especially the case when the CRISPR/Cas9 system is used in embryos. Here we review the pros and cons of mosaic mutations of gene-edited animals caused by using the CRISPR/Cas9 system in embryos. Furthermore, we will discuss the mechanisms underlying mosaic mutations resulting from the CRISPR/Cas9 system, as well as the possible strategies for reducing mosaicism. By developing ways to overcome mosaic mutations when using CRISPR/Cas9, genotyping for germline gene disruptions should become more reliable. This achievement will pave the way for using the CRISPR technology in the research and clinical applications where mosaicism is an issue.     

芝麻病毒病病原研究——Ⅰ.芝麻矮化坏死病害的鉴定

在湖北武昌芝麻上分离到的矮化坏死分离物(DNe-I)侵染芝麻引起严重矮化,叶片皱缩坏死。它能够摩擦接种侵染7科14种植物。在苋色藜、千日红上引起局部坏死斑,侵染油菜和百日菊引起系统花叶和黄化。DNe-I能够被桃蚜、花生蚜以非持久性方式进行传播。病毒体外稳定性状:存活期4天,钝化温度60～65℃,稀释限点4×10~(-4)。提纯病毒为线状粒体,长度为770nm。病毒外壳蛋自为单一亚基组成,分子量为30,700±600D。制备抗血清微量沉淀法测定其效价为1:256。在油菜病组织中,观察到风轮状及长直片层叠聚体类型的胞质内含体。在血清学性质上,该分离物与芜菁花叶病毒密切相关,与花生轻斑驳病毒和花生斑驳病毒弱相关,与大豆花叶病毒和西瓜花叶病毒不相关。基于上述性质,DNe-I被鉴定为芜菁花叶病毒。这是国内芜菁花叶病毒自然侵染芝麻的首次报道。     

不同大豆与大豆花叶病毒组合中胼胝质的荧光标记及其功能初探

选用6个大豆品种与4个不同的大豆花叶病毒株系,分别组成抗病级别不同的组合,通过对接种叶片与上位叶症状观察、苯胺蓝染色辅以荧光显微镜观察和药物学试验,探讨了不同抗病级别组合中胼胝质（即β-l,3-葡聚糖）积累的特点及其在大豆抵抗大豆花叶病毒侵染过程中的作用。试验结果表明,大豆接种病毒后,在抗病级别分别为0-3的各个组合的叶肉细胞中,在侵染早期（接种后6-72 h）不同的组合在不同时间点分别观察到了胼胝质荧光,且胼胝质荧光出现的时间与抗病级别密切相关,即品种的抗病性越强在侵染点处观察到胼胝质的时间越早;而在抗病级别为5的组合中一直未能观察到胼胝质荧光。另外,在抗病级别为0级和1级的各组合中给叶片预注射2-DDG(2-deoxy-D-glucose,一种胼胝质合成抑制剂）再接种病毒,在上位叶能观察到坏死斑的出现并且通过RT-PCR能够检测到大豆花叶病毒外壳蛋白基因。以上结果表明,大豆被大豆花叶病毒侵染后,品种的抗病性越强就会在侵染点处越早的积累胼胝质,胼胝质的沉积与大豆抗病毒侵染密切相关。     

菜豆黄色花叶病毒(BYMV)—新疆苜蓿分离株的鉴定

从新疆苜蓿黄斑花叶病株上分离到病毒分离物M-4,该分离物能引起多种豆科值物系统花叶,并在藜科植物上产生局部褪绿斑,易经汁液摩擦接种和蚜虫传毒,不经菜豆种子传毒。病毒致死温度60—65℃,体外保毒期4—5天,稀释限点10~(-3)—10~(-4)。病毒粒体线状,长约660—740nm,宽15nm;在感病的寄主叶片细胞中,电镜观察到风轮状、带状和环状内含体。免疫电镜法测定,该分离物与菜豆黄色花叶病毒(BYMV)抗血清有血清反应。经SDS-聚丙烯酰胺凝胶电泳和氨基酸自动分析仪分析分别测得该病毒的衣壳蛋白亚基分子量为16,200道尔顿,氨基酸残基数128个。鉴定结果认为,分离物M-4是BYMV的一个株系。     

Revised assignments for the beta-, gamma- and delta-subunits of the acetylcholine receptor structural model

Revised assignments for the bilayer helices of the beta-, gamma- and delta-subunits of the acetylcholine receptor are presented. A new feature of the model is extensive charge matching between the polar groups of the ion channel elements of different subunits.     

Symmetry control of chemical reactions: Applications to the Berry pseudorotation of five-coordinate transition metal complexes

A symmetry analysis of the Berry pseudorotation of trigonal bipyramidal transition metal complexes is presented. Predictions are made regarding which electronic configurations are allowed to undergo pseudorotation and which configurations are symmetry forbidden. A comparison to reported fluxional five-coordinate complexes shows that the predictions are consistent with experimental observations.     

甜瓜品种对西瓜花叶病毒-2的抗性与过氧化物酶的关系

甜瓜品种对西瓜花叶病毒－２的抗性与过氧化物酶的关系赵荣乐郑光宇（北京师范大学生物学系,北京１００８７５）关键词西瓜花叶病毒－２,抗性,过氧化物酶植物受病毒感染而引起过氧化物酶活性和同工酶谱的变化已有一些研究〔１－３〕,但未见到关于西瓜花叶病毒－２感染...