Influence of pH On 2,4-Dichlorophenoxyacetic and Acetic Acid Activity in Chlorella.

The Role of pH in the Permeability of Chlorella to 2,4-D.

“…have ranged from a purely anion effect (7,22) to the conclusion that only uncharged particles such as molecules are able to penetrate the lipid barrier presented by cell membranes, with the ions penetrating only slowly or not at all (1,6,8,9,11,15,16,18,19,1 Received Jantuary 10,1957. 2 Paper No.…”

“…After a temperature equilibration of 15 minutes, 1 ml of a solution of twice the desired concentration of 2,4-D, with 10 %,, of the total in the form of carboxyl-C14 2,4-D, was quiekly pipetted into each tube and the tube swirled for mixing. The time of addition of the 2,4-D* w^as taken as zero time for the particular tube.…”

Influence of 2,4-Dichlorophenoxyacetic Acid on Solute Uptake by Chlorella.

“…In addition to responses such as growth, cell elongation and changes in transpiration of leaves or fruits (7,14), which may obviously involve permeability changes, other auxin effects on plants may also be caused by permeability changes. The inhibition of photosynthesis by 2,4-D (4,16) Larger increases in permeability measured by plasmolysis-deplasmolysis time have been reported with indoleacetic acid treatments (5,6,8), although Ordin and Bonner (12) found that "optimal" (5 mg/liter) IAA had no effect on the diffusion of DHO into Avena coleoptile sections.…”

The effects of selected pesticides on ten isolates of terrestrial algae.

“…-3 At pH 4.49, a 3.02x10 M concentration of 2,4-0 was needed to produce complete photosynthesis inhibition (Erickson, et al, 1955). Exposure to high concentrations (10-2 M) at 10 C for 4 hours did not kill this alga (Wedding, et al, 1959).…”

“…Chlorella pyrenoidosa respiration was stimulated at moderate concentrations (about 35 ppm) (Erickson, et al, 1955;Wedding, et al, 1954) and inhibited at high concentrations (Wedding, et al, 1954). …”