洋葱染色体螺旋与放射环结构的电镜观察  

Observation of Chromosome Structure in Allium Cepa Cells by Means of Electron Microscopy

作　　者：陶伟[1] 刘晓玲[1] 赵允[1] 卢智刚[1] 翟中和[1] 

机构地区：[1]北京大学生命科学学院,北京100871

出　　处：《北京大学学报（自然科学版）》2000年第6期795-801,共7页Acta Scientiarum Naturalium Universitatis Pekinensis

摘　　要：染色体经DNA特异染色后 ,观察到其最高层次结构是螺旋的 ,而次级结构存在着放射环结构 ,即由直径为 2 5～ 30nm的DNA纤丝放射状折叠排列成约 2 50nm左右的染色单体丝 ;染色单体丝进一步螺旋形成中期染色体结构。这些观察结果和染色体的螺旋与放射环共存模型非常相似。这个模型应更接近于洋葱染色体真实结构。NAMA Ur is a specific DNA stain method that has been developed in recent years.In the ALLium cepa cells only the chromatin or chromosomes are heavily stained,the other components are bleached.After the chromosomes are stained by NAMA Ur,we have observed that the highest order structure of chromosomes is helical;while the secondary structure is radically folding. The DNA fibres with a diameter of 25～30?nm have radically folded into chromatid fibres in a diameter of approximately 250?nm. The above results present new evidence to support the radial loop and coils coexist mode of chromosome. This mode may more possibly accord with the real chromosome structure.

关 键 词：DNA特异染色 放射环结构 洋葱 染色体 螺旋结构 

分 类 号：Q343[生物学—遗传学]