Schaeffer D J, Tehseen W M, Johnson L R, McLaughlin G L, Hassan A S, Reynolds H A, Hansen L G
Department of Veterinary Biosciences, University of Illinois, Urbana 61801.
Qual Assur. 1991 Oct;1(1):31-41.
Asexual Dugesia dorotocephala planaria continuously exposed to 50 micrograms/beaker of Aroclor 1254 (A1254) and cadmium (Cd) developed tumors after 11 days of continuous exposure to 0.65 or 1.3 mg/liter Cd and after 23 days to 0.13 mg/liter Cd. The tumor rate at 14 days averaged 53% for the survivors in both 0.65 and 1.3 mg/liter Cd + A1254 and 40% at 0.13 mg/liter Cd + A1254. Other groups were either preexposed or coexposed to L-buthionine-S,R-sulfoximine (BSO), a specific inhibitor of glutathione synthesis. In the presence of A1254 (50 micrograms/beaker), animals continuously exposed to BSO and 0.13 mg/liter Cd first developed tumors at 18 days, with a tumor yield equal to 41% of the survivors. Tumors developed by 6 days at 0.65 mg/liter Cd, with a yield equal to 75% of survivors. At 1.3 mg/liter Cd, BSO did not change the rate or frequency of planarian tumor production. Continuous BSO always produced high mortality over 20 days. In contrast, a 24-h preexposure to BSO caused little mortality. In these groups, tumor yields increased with cadmium concentration (0.13, 0.25, 0.65 mg/liter), and the large cocarcinogenic effect of A1254 was clearly evident. No tumors developed in animals exposed only to 50 micrograms/beaker of Aroclor 1254 or continuously only to 1 mM BSO.
将无性生殖的三角涡虫（Dugesia dorotocephala）涡虫持续暴露于每烧杯50微克的多氯联苯混合物Aroclor 1254（A1254）和镉（Cd）中，在持续暴露于0.65或1.3毫克/升的镉11天后，以及在暴露于0.13毫克/升的镉23天后会出现肿瘤。在0.65和1.3毫克/升镉 + A1254组中，14天时幸存者的肿瘤发生率平均为53%，在0.13毫克/升镉 + A1254组中为40%。其他组要么预先暴露，要么同时暴露于L-丁硫氨酸-S，R-亚砜亚胺（BSO），一种谷胱甘肽合成的特异性抑制剂。在存在A1254（每烧杯50微克）的情况下，持续暴露于BSO和0.13毫克/升镉的动物在18天时首次出现肿瘤，肿瘤发生率相当于幸存者的41%。在0.65毫克/升镉时，6天时出现肿瘤，发生率相当于幸存者的75%。在1.3毫克/升镉时，BSO没有改变涡虫肿瘤产生的速率或频率。持续使用BSO在20天内总是导致高死亡率。相比之下，24小时预先暴露于BSO导致的死亡率很低。在这些组中，肿瘤发生率随镉浓度（0.13、0.25、0.65毫克/升）增加，并且A1254的巨大促癌作用明显。仅暴露于每烧杯50微克的Aroclor 1254或仅持续暴露于1毫摩尔BSO的动物未出现肿瘤。
