仓鼠体内注射不同剂量BrdU的细胞遗传学效应--应用活性炭吸附BrdU一次注射SCD法

THE CYTOGENETICAL EFFECTS OF DIFFERENT DOSAGE OF BrdU INJECTED INTO CHINESE HAMSTERS IN VIVO The application of the modified method of"SCD by a single intraperitoneal injection of activated charcoal-absorbed BrdU

5-溴脱氧脲嘧啶核苷(5—bromo-2′-deoxyuridine,BrdU)能够代替胸腺嘧啶核苷(thymidine)掺入DNA,使姐妹染色单体分色,计算姐妹染色单体互换(sister Chromatid exchange,SCE)率,可以估计DNA的损伤。因而,近年来已广泛地应用SCE测定各种诱变因子的活力。但是研究BrdU本身诱变活力的报道不多,且多是离体的研究,体内实验很少。目前国内尚无类似的报道。 本文以我国特产仓鼠为实验材料,采取一次性腹腔注射BrdU活性炭悬浮液方法,研究不同剂量BrdU对仓鼠骨髓淋巴细胞SCE频率、染色体畸变率、分裂指数、细胞增殖周期以及对姐妹染色单体分色的影响。

The effects of different dosages of 5’-bromodeoxyuridine(BrdU)on the frequency of SCE,chromosomal aberration rate,cell cycle,sister chromatid differentiation(SCD)of the bone marrow cells of Chinese hamsters(Cricetulus baradensis)in vivo were studied by means of a single intraperitoneal injection of activated charcoal-suspended BrdU into hamsters with an average weight of about 23g.The results indicated that there were no significant difference among SCEs induced by the dosages of 0.225mg,0.450mg,0.675mg/g(body weight)and thereby 3 per cell for the"spontaneous"frequency of SCE should be concluded.The frequency of SCE markedly increased at the dosage of above 0.90mg/g,while at the dosage of 3.60mg/g,the frequency of SCE induced was nearly 2.80 times as high as that of 0.225 mg/g.In accordence with our results,a new concept was suggested that there must have been a threshold of BrdU dosage in an approximation of the frequency of"spontaneous"SCE in mammals,and that of the SCE would significantly increase if the dosages of BrdU was larger than the threshold.The effects of different dosages of BrdU on chromosomal aberration rate,cell cycle,and mitotic index of the bone marrow cells were also observed.The clear increase of gaps and breakages in chromatids and isochromatids,the delay of cell cycle,and the decrease of mitotic index were relaled to the dosage BrdU.These results proved that BrdU is a weak mutagen in itself.The analysis of the effects of different dosage of BrdU on SCD suggested that the quality of diffcrcntation was positively related to the dosage of BrdU.In addition the comparison of the effects of several pll values of 2 x SSC solution on SCD indicated that pH 7.5 is the most optimal.