Department of Biological Sciences and Center for Great Lakes Studies, University of Wisconsin-Milwaukee, PO Box 413 Milwaukee, WI 53201, U.S.A.
Tissue Cell. 1986;18(3):395-405. doi: 10.1016/0040-8166(86)90059-5.
Accumulation and effects of cadmium were investigated in Chironomus thummi larvae exposed to 10, 100 and 250 mug radiolabeled Cd/1 for up to 4 days. (1) After 4 days, average cadmium accumulation was 6.6 ng Cd/mg dry weight (10 mug Cd/1 exposure) and 177 ng Cd/mg dry weight (250 mug Cd/1 exposure). (2) Dissection studies showed that by 32 hr of exposure to both cadmium concentrations, 63.5-81.4% of accumulated cadmium was confined to the posterior midgut epithelium. Light microscope autoradiography similarly showed accumulations of cadmium in posterior midgut epithelium and smaller amounts in fat body and muscle. Little cadmium was associated with Malphigian tubules, haemocoel, anterior midgut or exoskeleton. (3) After exposure to 10 or 250 mug Cd/1, 60-75% of cadmium in ultracentrifuged homogenates of whole animals or dissected guts was associated with the resulting supernatant. When supernatants were further analyzed by gel chromatography, cadmium eluted with both a high and low molecular weight peak. The relative proportions of cadmium in the two peaks varied with concentration and length of exposure. (4) Transmission electron microscopy of posterior midgut cells from animals exposed to cadmium demonstrated frequent mitochondrial lesions. Exposure to high cadmium concentrations caused some posterior midgut cells to undergo generalized structural degeneration.
研究了摇蚊幼虫在暴露于 10、100 和 250μg 放射性标记 Cd/1 下 4 天内镉的积累和影响。（1）4 天后，平均镉积累量为 6.6ng Cd/mg 干重（10μg Cd/1 暴露）和 177ng Cd/mg 干重（250μg Cd/1 暴露）。（2）解剖研究表明，在接触这两种镉浓度 32 小时后，63.5-81.4%的累积镉被限制在后中肠上皮中。光镜放射自显影同样显示镉在中肠后上皮中的积累，在脂肪体和肌肉中积累较少。很少有镉与马尔皮基小管、血腔、前中肠或外骨骼有关。（3）在暴露于 10 或 250μg Cd/1 后，动物或解剖肠道的超离心匀浆中 60-75%的镉与所得上清液有关。当上清液进一步通过凝胶色谱法分析时，镉与高分子量和低分子量峰一起洗脱。两个峰中镉的相对比例随浓度和暴露时间的变化而变化。（4）暴露于镉的后肠细胞的透射电子显微镜显示频繁的线粒体损伤。暴露于高浓度镉会导致一些后肠细胞发生广泛的结构退化。
