苜蓿花叶病毒粒子的统计学特征和分组

CStatistical features and grouping of alfalfa mosaic virus particles

以一株来自于白车根草 (Trifolium repens L.)上的苜蓿花叶病毒分离物 AMV- SY为材料 ,在电镜下观察测量经醋酸铀负染的 196个提纯病毒粒子 ,按其长度分成等距离的 5个组 ,用统计分析方法确定组间的差异 .所得各组粒子的平均大小依次是组 :(2 0 .4± 2 .5) nm× (18.7± 2 .3) nm,组 :(2 8.0± 2 .4 ) nm× (18.1± 2 .1) nm,组 :(36 .0± 2 .4 ) nm× (17.2± 2 .0 ) nm,组 :(4 4 .8± 2 .7)nm× (16 .9± 2 .0 ) nm,组 :(52 .0± 3.0 ) nm× (17.4± 1.0 ) nm.它们分别相当于前人根据 X-射线衍射或核磁共振所测定的 Ta- t,Ta- b,Tb,M和 B型病毒粒子 .方差分析表明 ,5组病毒粒子间长度差异极显著 ,即组 <组 <组 <组 <组 ;病毒粒子宽度差异也极显著 ,但仅组 粒子的宽度明显大于组 和组 ,说明在没有病毒 RNA参与的情况下 ,单由不含病毒 RNA的外壳蛋白亚基所构成的粒子其横向结构较为松散 .对 AMV统计分析的结果与前人根据对病毒粒子结晶中典型的粒子进行 X射线衍射分析或计算机模拟所获得的结果基本吻合 ,但组 粒子 ,即最长一组 AMV病毒粒子的统计长度明显小于结晶中 X-射线衍射分析所测得最长的

One hundred and ninety six particles of the alfalfa mosaic virus (AMV SY) previously isolated from Trifolium repens L was measured under electronic microscope and statistically analyzed Five groups were distinguished based on the particle lengths measured The particles in Group Ⅰ were measured as (20 4 ±2 5) nm×(18 7±2 3) nm in size, Group Ⅱ (28 0 ±2 4) nm×(18 1±2 1) nm, Group Ⅲ (36 0 ±2 4) nm×(17 2±2 0) nm, Group Ⅳ (44 8 ±2 7) nm×(16 9±2 0) nm, and Group Ⅴ (52 0 ±3 0) nm×(17 4±1 0) nm, respectively The grouping corresponded to the AMV particle types of Ta t, Ta b, Tb, M and B previously reported based on X ray diffraction of the crystallized virions The lengths in different particle groups were significantly different based on the analysis of variance ( F =511 83, P <0 01), and the particle length of Group Ⅴ was shorter than the length of the type B virions previously reported The widths also differed significantly among the five groups ( F =4 37, P <0 01) The particles in Group Ⅰ, composed of coat protein subunits alone, was clearly broader than those in Groups Ⅲ and Ⅳ That indicates that the structure of the particles in Group Ⅰ is looser than those in other groups due to interaction of coat protein subunits with viral RNA