The effect of 2,4-dichlorophenoxyacetic acid upon the metabolism and composition of soybean hypocotyl mitochondria

Comparison of uncoupling activities of chlorophenoxy herbicides in rat liver mitochondria

The effects of the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 4-chloro-2-methylphenoxyacetic acid (MCPA) and 2-(2,4,5-trichlorophenoxy)propionic acid (2,4,5-TP) on respiration and oxidative phosphorylation in rat liver mitochondria were examined in vitro. Respiration rates of glutamate, malate and succinate were investigated in the presence of each herbicide (0.1-4.0 mM). At lower concentrations, all herbicides stimulated state 4 respiration, decreased the respiratory control ratio and the ADP/O ratio. The respiration rate in state 3 and uncoupled state was unaffected. At higher concentrations all bioenergetic parameters, respiration in state 4, 3 and uncoupled state, as well as respiratory control ratio and ADP/O, were inhibited in a concentration-dependent manner. These data indicate that these herbicides alter energy metabolism in rat liver mitochondria by uncoupling of oxidative phosphorylation. 2,4,5-TP possesses the strongest uncoupling properties followed by 2,4,5-T, MCPA and 2,4-D in that order.

Toxicological implications of pesticides: their toxic effects on seeds of food plants

Pesticides are widely used for the protection of economic crops from a variety of noxious pests. The repeated and indiscriminate uses and the extreme stability of certain pesticides have led to their accumulation in plants, animals, soils and sediments, thus effecting widespread contamination of the environment. Soil contaminants are especially serious because they can inhibit or impair the seed germination of our food and feed crops. Seeds can come in close contact with pesticides through processes such as prematurity application, fumigation, seed dressings, and seed treatments. Several reports have indicated the toxic effects of pesticides on seed germination. Possible mechanisms of the toxic action on pesticides during the germination of seeds have been discussed with emphasis on biochemical, histological, and cytological alterations. Bioassay procedures employing seed germination as a smiple, feasible, economical, time-saving indicator of toxicity have been described briefly. Attention is then drawn to the possible potential health hazards arising from the presence of pesticidal chemicals in food plants since the toxicological implications of long term exposure to pesticides are often more far-reaching.

Ribosomal and mitochondrial peroxidase isoenzymes of the lentil (Lens culinaris) root

Ribosome- and mitochondria-rich preparations were obtained from lentil roots and their peroxidase isoenzymes examined by starch gel electrophoresis. Seven isoenzymes were shown to be associated with both the ribosomal and mitochondrial fractions.The apparent similarity between ribosomal and mitochondrial isoenzyme patterns, together with the observation that a considerable amount of peroxidase activity dissociated from the ribosomes during sedimentation of the ribosomal preparation into a sucrose gradient, suggested that at least some of these isoperoxidases were attached to membranes.

The incorporation of amino acids into the protein of isolated soya bean mitochondria

A system involving the incorporation of amino acids into the protein of mitochondria isolated aseptically from soya bean hypocotyls has been partially characterized. Incorporation is optimal at pH 7.4, is dependent on magnesium, phosphate and succinate, is resistant to pancreatic RNAase and cycloheximide, but is sensitive to D-threo-chloramphenicol, oligomycin, DNP, and changes in osmotic concentration.