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The effect of Alanap, N‐1‐naphthylphthalamic acid (NPA), on the permeability of onion (Allium cepa) epidermal cells was studied by means of a plasmometric method. Urea, 1,3‐dimethylurea, and water were used for the test of permeability. It was found that the treatment of onion epidermis with NPA at various concentration (5 × 10–3 to 5 × 10–6M) altered the deplasmolysis rates and the absolute permeability constants. However, NPA did not alter the osmotic value of the treated cells. It was suggested that NPA treatment altered the permeability of onion epidermal cells due to the effect of this herbicide on the plasma membrane. [ABSTRACT FROM AUTHOR]

An Escherichia coli ‘permeabilized’ cell system obtained by treatment in high sucrose concentration, because of its depletion from endogenous metabolites, its low nuclease, phosphatase and phosphokinase content, catalyzes a very efficient polymerisation of the common ribonucleoside diphosphates (UDP, CDP, ADP and GDP) presumably through the polynucleotide phosphorylase retained within the cells after osmotic shock. Accordingly incorporation of nucleotides into polymers is insensitive to actinomycin D and does not take place in the presence of Mg2+ ions with E. coli Q13 a strain in which the polynucleotide phosphorylase is a Mn-dependent enzyme. Polymers containing U, C, G, or A as the only constituting nucleosides have been found to accumulate for several hours at a linear rate, in the supernatant phase from osmotically shocked E, coli D10. If, following the arrest of polymer formation the amino acid coded for by the corresponding triplet is added to the incubation medium together with an energy-yielding system, a very efficient incorporation of this amino acid (and of this amino acid only) into an acid-precipitable material takes place. The resulting product (presumably an homopolypeptide) is associated with the cell bodies. Translation of the preformed poly-ribonucleotide is concomitant with its nucleolytic cleavage by a K-dependent nuclease. [ABSTRACT FROM AUTHOR]

Concentrations of the major component ions (K., Na and Cl) of sea water and cells of Enteromorpha intestinalis(L. ) Link were determined, Measurements of the electric potential difference across the plasmalemma and the influx and efflux of each ion indicate that K and Cl are actively imported and Na actively exported Estimates of membrane permeability to the passive diffusive fluxes of these three ions alone have been used to explain the origin of the cell membrane potential. Tracer ion exchange kinetics are taken as showing that the tonoplast is more permeable than the plasmalemma to each ion. [ABSTRACT FROM AUTHOR]

The effect of aspermy virus infection the water status of tomato leaves was studied. Infected leaves had a higher relative water content than controls, the increase being related to inoculum concentration. This was shown to be caused by an inability to take up water rather than a truly higher water content. It is suggested that this may be the result of a reduction in the permeability of cell membranes. [ABSTRACT FROM AUTHOR]