Removal of Inhibiting Effects on Nitella of Certain Buffer Mixtures and Acids.

Abstract

Living cells of Nitella (collected in New York in autumn) were exposed 1 for 10 minutes to (1) M/150 phosphate buffer solution at pH 5.5, (2) 5 × 10⁻⁵ M phosphoric acid 2 (at about pH 4.3), and (3) 5 × 10⁻⁵ M hydrochloric acid (at about pH 4.2), and then placed in a solution of brilliant cresyl blue. 3 The rate of penetration of dye into the vacuole, as compared to that of the control (cells transferred from tap water into the dye solution), was found to decrease about 50 per cent in (1), 37 per cent in 4 (2), and 25 per cent 5 in (3).

This inhibiting effect was not removed when cells, previously exposed to the solutions above mentioned, were washed for ½ minute either in M/150 phosphate buffer solution at pH 7.7, or in M/150 borate buffer solution at pH 7.7 containing 0.02 M sodium chloride. In the latter case there was a greater inhibiting effect. The inhibiting effect of hydrochloric acid and phosphoric acid was very slightly reduced while that of the phosphate buffer mixture at pH 5.4 was not changed when cells previously exposed to these solutions were washed in M/150 borate buffer solution at pH 7.7 for ½ minute.

The inhibiting effect, however, was completely removed when cells previously exposed to the solutions mentioned were treated in any of the following ways:

(a) By placing the cells in the dye solution made up with M/150 phosphate buffer mixture. The same result was obtained whether the dye solution was stirred or not.

(b) By placing the cells in the dye solution made up with M/150 borate buffer mixture, containing either 0.02 M sodium chloride or 0.01 M magnesium chloride.