Kale P G, Baum J W
Mutat Res. 1983 Apr;113(2):135-43. doi: 10.1016/0165-1161(83)90225-x.
Drosophila embryos were treated with gaseous ethylene dibromide at concentrations ranging from 0.26 to 200 ppm, thereby exposing a homogeneous and non-dividing population of primordial spermatogonia. Mutations were induced at exposures as low as 1 ppm for 3 h indicating the sensitivity of spermatogonia and the usefulness of this life-cycle stage for detection of mutagens. Other advantages of using embryos are also discussed. The relations between exposure vs. percentage of mutations per chromosome tested and vs. percentage of positive males were linear at low exposures indicating the possibility of extrapolation of the data to very low doses and lack of a threshold. For some males 50% of the progeny carried a mutation, and mutations continued to appear in all tested broods providing evidence of damage to stem cells undergoing quasi-dichotomous divisions. Damage to the stem cells is important in terms of total effects on the gene pool and may contribute more mutations than that due to damage in the more sensitive spermatocytes and spermatids. Spermatogonial stages, therefore, should also be considered in mutagen screening and risk-benefit analyses.
用浓度范围为0.26至200 ppm的气态二溴乙烷处理果蝇胚胎，从而使原始精原细胞群体均匀且不分裂。在低至1 ppm暴露3小时的情况下即可诱导突变，这表明精原细胞的敏感性以及该生命周期阶段在检测诱变剂方面的有用性。还讨论了使用胚胎的其他优点。在低暴露水平下，暴露量与每条测试染色体的突变百分比以及阳性雄性百分比之间的关系呈线性，这表明有可能将数据外推至非常低的剂量且不存在阈值。对于一些雄性，50%的后代携带突变，并且在所有测试的育雏中都持续出现突变，这为经历准二分分裂的干细胞受到损伤提供了证据。就对基因库的总体影响而言，干细胞的损伤很重要，并且可能比更敏感的精母细胞和精子细胞受到损伤导致更多的突变。因此，在诱变剂筛选和风险效益分析中也应考虑精原细胞阶段。
