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H PASSOW

Publications and source records attributed to H PASSOW.

At least 19 recordsLinked to original sources
PubMed1960

The binding of mercury by the yeast cell in relation to changes in permeability.

Yeast cells exposed to mercuric chloride suffer irreversible damage to the membrane, resulting in a loss of potassium and cellular anions to the medium. The maximal loss of K(+), but not the time course of K(+) loss is related to the mercury concentration, the relationship following a normal curve on a graph of log-concentration versus effect. It is concluded that the response is all or none for individual cells, and that with increasing concentrations of metal, the threshold is exceeded in an increasing proportion of the cells. Parallel studies of the binding of mercury by the cells indicate two distinct phases, only one of which is associated with the physiological response. The binding process is relatively slow but reaches an equilibrium state. Desorption is markedly dependent on temperature. No simple stoichiometric relationship exists between the binding of mercury and the physiological response (K(+) loss).

Mercury↗
PubMed1959

An all-ornone response in thh release of potassium by yeast cells with methylene blue and other basic redox dyes.

Basic redox dyes, such as methylene blue, induce a loss of K(+) from yeast cells. The maximal loss, rather than the rate of loss, is related to the dye concentration, the response following a normal distribution on a plot of log-dose, versus percentage loss of K(+). This fact taken together with the observed correlation between K(+) loss and frequency of staining (as measured by microscopic observation), indicates that the response is all-or-none for individual cells. The response is produced by all the basic redox dyes tested (9), but by none of the acidic dyes (4). However, only the oxidized form of the dye is effective. Cations protect the cells from the basic dyes in a competitive manner, the bivalent cations (especially UO(2) (++)) being more effective than monovalent cations. It is suggested that the action of the dyes involves two steps, the first a binding to ribonucleic acid in the cell membrane (with competition from cations) and the second, an oxidation of neighboring sulfhydryl groups to the disulfide form. At a threshold level, unique for each cell, a generalized membrane breakdown occurs, resulting in the release of potassium and of other cytoplasmic constituents.

Cations, Monovalent↗