Luchnik N V, Porjadkova N A
Chromosoma. 1977 Aug 18;63(1):11-20. doi: 10.1007/BF00292938.
Human lymphocytes were incubated during two mitotic cycles in the presence of 5-bromodeoxyuridine and differentiation between chromatids was obtained with combined "Hoechst 33258" and azur-eosine staining. Analysis of non-irradiated cells revealed numerous sister chromatid exchanges (SCE) and no abnormalities of "harlequine" appearance of chromosomes. When, however, the cells were irradiated, an identical staining (IS, isostaining) of some chromosomes or chromosome segments were observed. Production of IS was accompanied by decrease of the frequency of SCE, the total frequency of SCE+IS remained, however, the same as in control. An antagonism between SCE and IS was established: the frequency of SCE decreased in the cells with multiple IS, and chromosomes with both SCE and IS were only rarely observed. Thus, IS is neither an artifact nor a physiologic event but a phenomenon induced by radiation. The reliable existence of IS is considered as an evidence for binemic structure of chromatid. It is suggested that some mechanism of lateral spread of genetic information is involved in the production of SCE. If delayed by radiation, the spread could be restricted only to a fraction of chromosome cross-section resulting in IS.
人淋巴细胞在5-溴脱氧尿苷存在的情况下进行两个有丝分裂周期的培养，并用“ Hoechst 33258”和天青-曙红联合染色来区分染色单体。对未受辐照细胞的分析显示出大量姐妹染色单体交换（SCE），且染色体未出现“哈勒喹因”外观异常。然而，当细胞受到辐照时，观察到一些染色体或染色体片段出现相同染色（IS，等染色）。IS的产生伴随着SCE频率的降低，不过SCE + IS的总频率与对照组相同。SCE和IS之间存在拮抗作用：在具有多个IS的细胞中SCE频率降低，同时具有SCE和IS的染色体很少被观察到。因此，IS既不是人为现象也不是生理事件，而是由辐射诱导的一种现象。IS的可靠存在被视为染色单体双联体结构的证据。有人提出，遗传信息的侧向传播机制参与了SCE的产生。如果被辐射延迟，这种传播可能仅局限于染色体横截面的一部分，从而导致IS。
