CELLULAR TARGET SITES OF HEAVY METAL EXPOSED CELLS

拟议研究的目的是调查 测试细胞中重金属区室化的程度， 测定金属离子对膜的特定影响 结构和细胞器分布。 将进行研究 在选定的剂量水平下， 显微镜检查以确定是否发生细胞损伤。 的 酿酒酵母和普通小球藻 暴露在不同浓度的五种环境- 重金属（Cd、Cu、Hg、Pb和Zn）， 测定暴露于金属的细胞的EC 50。 以下 然后将确定：（1）质膜的程度 通过对大小、形状、数量和分布的分析， 基本粒子（蛋白质）的冷冻断裂 制备，（2）重金属的位置，特别是细胞 使用能量色散X射线空气微分析的车厢， 干燥和/或冷冻切片的标本，（3）细胞结构， 在重金属的作用下， 浓度使用随机取向的形态测定分析 薄片细胞，以及（4）如果有，重金属 通过使用原子吸收分光光度法定位 对由破碎细胞制备的级分进行了测定。 从这些研究的结果来看，预计我们应该 深入了解重金属是如何造成某些有害的 影响细胞。 迄今为止对小球藻的研究表明， 膜颗粒的分析也可能被镉改变 就像其他细胞器和内含物一样 这些信息 应该适用于所有细胞水平的重金属效应 包括对人体的影响 已经发现，在大多数情况下，来自任何来源的细胞都具有 类似的回应。 因此，这里获得的细胞数据应该是 在一定范围内适用于所有细胞。 数据的使用 我们的系统应该提供数据， 可以获得对重金属的响应。 该信息可以 然后用于包括人类在内的整个动物反应 重金属的危害当然是在细胞水平上。

It is the purpose of the proposed research to investigate the degree of heavy metal compartmentalization in test cells and to determine selected specific effects of metal ions on membrane structure and organelle distribution. Studies are to be performed at selected dose levels with conventional transmission electron microscopy to determine if cellular damage has occurred. The organisms Saccharomyces cerevisiae and Chlorella vulgaris will be exposed to various concentrations of five environmentally- significant heavy metals (Cd, Cu, Hg, Pb and Zn) in order to determine EC50 of the cells exposed to the metals. The following will then be determined: (1) the degree of plasma membrane alteration by analyses on the size, shape, number and distribution of elementary particles (proteins) revealed in freeze-fracture preparation, (2) heavy metal location in particular cellular compartments using energy-dispersive X-ray microanalysis of air- dried and/or cryosectioned specimens, (3) cell structures which are most altered by the administration of heavy metal concentrations using morphometric analysis of randomly-oriented thin-sectioned cells, and (4) if any, where heavy metals are localized through the use of atomic absorption spectrophotometry on fraction prepared from disrupted cells. From the results of these studies it is anticipated that we should gain insights as to how heavy metals cause certain detrimental affects on cells. Work to date on Chlorella vulgaris indicates that analysis of membrane particles may be altered by Cd as well as certain other cell organelles and inclusions. This information should be applicable to heavy metal effects at all cellular levels including human effects. It has been found that in most cases cells from any source have a similar response. Thus the cellular data obtained here should be applicable to all cells within certain limits. Use of data from our system should provide data from which models of the cellular response to heavy metals can be obtained. This information can then be used in regard to whole animal response including humans to heavy metals as the damage is, of course, at the cellular level.