中国棉铃虫核多角体病毒VHA273毒株DNA的特性

CHARACTERIZATION OF DNA ISOLATED FROM VHA273 STRAIN OF HELIOTHIS ARMIGERA NUCLEAR POLYHEDROSIS VIRUS

VHA273毒株纯多角体经碱解、酶解及饱和酚一步法和二步法抽提的基因组,具有典型的DNA吸收光谱。吲哚法亦确证为DNA,无RNA。超离心沉降分析,扫描出主峰沉降常数为26S,次峰9.7S。热变性温度法测得Tm=89.6℃,计算(G+C)％=49.53。电镜观察DNA呈3种典型形态。大的闭环DNA平均长度29.8μ,计算得分子量是61.7×10~6;有少量极小闭环DNA存在。0.7％琼脂糖凝胶电泳显示,DNA主带清晰浓重,发现还有5条微弱次带,约2.5～3.7kb。该DNA用4种限制性核酸内切酶Bg1 Ⅱ、BamHⅠ、EcoRⅠ和HindⅢ分别酶切成11、8、14和13条带。用片段积加法求出的分子量彼此很接近,平均为67.0×10~6道尔顿。酶切图谱显示,5条弱带对4种内切酶概不敏感。

VHA273 genome were extracted by water-saturated phenol by one-step or two-step methods. The genome appeared to be characteristics of DNA in ultroviolet absorption spsctrum and indol test. Ultracentrifugation analysis of the DNA showed a major peak ( 26S ) and a minor peak ( 9.7S ) . The melting temperature of the DNA was 89.6℃, therefore, its content of(G+C) was about 49.53%. Electron microscopy observation showed that there were many big closed circular DNA and a few small ones. The mean length of the big DNAs was 29.8μ. and its calculated molecular weight was 61.7×106 D. The extracted DNA appeared as a major band and 5 minor bands by 0.7% agarose gel electrophoresis. Restriction endonuclease analysis of electrophoresis recovered DNA revealed that Bgl II , BamHI, EcoRI, HindIII cleaved the DNA into 11, 8, 14, 13 fragments respectively. The molecular weight added up were very close to one another, its mean value being about 67.0×106D. The restriction pattern shoved that the 5 minor fragments were resistant to the 4 endoaucleases.