Taniguchi T, Takayama S
Chromosoma. 1987;95(1):13-6. doi: 10.1007/BF00293836.
Chinese hamster chromosomes were differentially substituted with 50 microM 5-bromodeoxyuridine (BrdU) to obtain chromosomes with bifilarly and unifilarly substituted (BB-TB) and unifilarly and non-substituted (TB-TT) chromatid constitutions. To avoid the effect of Giemsa staining on the ultrastructure of chromosomes, unstained preparations were exclusively used. When TB-TT chromosomes were prepared with the conventional air-drying method followed by the osmium tetroxide-thiocarbohydrazide (OsO4-TCH) technique and examined by scanning electron microscopy (SEM), the TB-chromatid appeared somewhat more slender and showed more conspicuous spiral structures, thereby appearing more loosened compared to the TT-chromatid. At higher magnifications, however, 30 nm chromatin fibres which were seen to constitute both chromatids showed no discernible differences in dimension between the TT- and TB-chromatids. On the other hand, TB-TT chromosomes specially prepared for SEM without the process of air-drying appeared in their entirety less extended and no spiral configuration was observed even in the TB-chromatid. The TB-chromatid instead appeared rather less loosened than the TT-chromatid whereas thick fibre-like structures which in turn seemed to consist of 30 nm fibres were more easily discernible in the TT-chromatid compared to the TB. Such seemingly contradictory results obtained from the two different preparatory procedures were tentatively explained on the basis of our multiple coiling model (Taniguchi and Takayama 1986).
用50微摩尔5-溴脱氧尿苷（BrdU）对中国仓鼠染色体进行差异取代，以获得具有双股和单股取代（BB-TB）以及单股和未取代（TB-TT）染色单体组成的染色体。为避免吉姆萨染色对染色体超微结构的影响，仅使用未染色的标本。当用传统空气干燥法制备TB-TT染色体，随后采用四氧化锇-硫代碳酰肼（OsO4-TCH）技术，并通过扫描电子显微镜（SEM）检查时，TB染色单体显得稍细一些，呈现出更明显的螺旋结构，因此与TT染色单体相比显得更松散。然而，在更高放大倍数下，构成两条染色单体的30纳米染色质纤维在TT染色单体和TB染色单体之间的尺寸上没有明显差异。另一方面，专门为SEM制备的未经空气干燥过程的TB-TT染色体整体上显得伸展程度较小，即使在TB染色单体中也未观察到螺旋构型。相反，TB染色单体看起来比TT染色单体更不松散，而与TB相比，TT染色单体中似乎由30纳米纤维组成的粗纤维状结构更容易辨别。基于我们的多重螺旋模型（Taniguchi和Takayama，1986），对从两种不同制备程序获得的这种看似矛盾的结果进行了初步解释。
