Physiology of the Cell Surface of Neurospora Ascospores. IV. The Functions of Surface Binding Sites.

Abstract

The prior adsorption of Ag+, UO2++, and phenylmercuribenzoate (PCB) to sites on the cell surface did not result in faster penetration to the interior, as judged by their effect upon the respiration of germinating ascospores of Neurospora tetrasperma. Moreover, the blocking of adsorbing sites by treatment with hexol nitrate or cobalt hexammine chloride did not result in decreased uptake of Ag+ or in a delay in the time when the respiratory effects of Ag+, UO2++, and PCB were manifested. These results lead to the conclusion that adsorption to the surface of the cell is not a necessary prelude to penetration. Cations bound to the surface account for about 3-11% of the total cations of the cell. Calculations of the area of the cell surface disclose that adsorbed cations are probably arranged in depth on the cell surface rather than in a single layer.