自由基和温度对大麦根尖细胞姊妹染色单体交换的影响

EFFECT OF FREE RADICALS AND TEMPERATURE ON SISTER CHROMATID EXCHANGES IN HORDEUM VULGARE L.

研究了抗坏血酸、丝裂霉素C、阿霉素和马来酰肼等药物在大麦(Hordeum vulgare L.)中诱导姊妹染色单体交换(sister chromatid exchange,SCE)频率增高的原因,发现它们在诱导SCE形成的过程中自由基起了重要作用。还研究了温度对细胞平均世代时间(averagegeneration time,AGT)和SCE的影响。结果表明在20—26℃范围内,随着温度的上升,SCE频率呈线性下降;AGT和SCE频率之间存在着显著的正相关。

The clastogenic (chromosome-damaging) effect of many chemical and physical agents is believed to be mediated by reactive oxygen-derived radicals. The interaction of these free ra- dicals with DNA and the significance of tbe radical-induced DNA lesions in mutagenesis and carcinogenesis have been the suhjects of increasing interest during recent years. Sister chro- matid exchange (SCE) reflects an interchange between DNA molecules at bomologous loci within a replicating chromosome. SCE analysis was found to have increased use for monitor- ing the exposure of cell to mutagenic carclnogens. The authors found that the induction of SCEs in cells of Hordeum vulgare L. by ascorbic acid, mitomycin C, adriamycin and maleic hydrazid was through the action of free radicals. They also studied the influence of growth temperature on average generation time(ACT) and SCEs. and disclosed a close correlation bet- ween AGT and SCEs. The Brdu-Giemsa techniques were used for the detection of SCEs and AGT in cytological preparations of metaphase chromosomes.