RESUMO
Uranium accumulated extracellularly on the surfaces of Saccharomyces cerevisiae cells. The rate and extent of accumulation were subject to environmental parameters, such as pH, temperature, and interference by certain anions and cations. Uranium accumulation by Pseudomonas aeruginosa occurred intracellularly and was extremely rapid (<10 s), and no response to environmental parameters could be detected. Metabolism was not required for metal uptake by either organism. Cell-bound uranium reached a concentration of 10 to 15% of the dry cell weight, but only 32% of the S. cerevisiae cells and 44% of the P. aeruginosa cells within a given population possessed visible uranium deposits when examined by electron microscopy. Rates of uranium uptake by S. cerevisiae were increased by chemical pretreatment of the cells. Uranium could be removed chemically from S. cerevisiae cells, and the cells could then be reused as a biosorbent.
RESUMO
A prototype centrifugal system has been developed that permits parallel photometric monitoring of eluate streams from a radial array of chromatographic columns. The modular rotor design consists of a discoidal center insert for eluent and sample apportionment, the chromatographic columns, and flow-through cuvetts-all mounted on an aluminum base plate. A common sample is introduced simultaneously to each column; a single eluent stream is used for all columns. The goal is to assay simultaneously for eight to 16 serum proteins separated by affinity chromatography from a single sample. The system is here exemplified by the use of immunosorbents (consisting of antibodies to human immunoglobulins covalently bound to alumina particles) to allow simultaneous determinations of IgG AND IgM from a single human serum sample in less than 16 min.
