The kinetics of methylparathion and fenvalerate action and Ca2+ antagonism on the activity of (Ca2+ + Mg2+)-ATPase in sorghum (Sorghum bicolor L.)

Suspensions of mechanically isolated Asparagus sprengeri Regel mesophyll cells were used to investigate the influence of various carboxyester compounds on rates of net H+ efflux in the dark or light and photosynthetic O2 production. Addition of 0.15 to 1.5 millimolar malathion, α-naphthyl acetate, phenyl acetate, or p-nitrophenyl acetate stimulated H+ efflux and inhibited photosynthesis within 1 minute. In contrast, the more polar esters methyl acetoacetate or ethyl p-aminobenzoate had little or no effect on either of these two processes. A 0.15 millimolar concentration of α-naphthylacetate stimulated the normal rate of H+ efflux, 0.77 nanomoles H+ per 106 cells per minute by 750% and inhibited photosynthesis by 100%. The four active carboxyester compounds also stimulated H+ efflux after the normal rate of H+ efflux was eliminated with 0.01 milligrams per milliliter oligomycin or 100% N2. Oligomycin reduced the ATP level by 70%. Incubation of cells with malathion, α-naphthyl acetate, or p-nitrophenyl acetate resulted in the generation of the respective hydrolysis products ethanol, α-naphthol, and p-nitrophenol. It is proposed that inhibition of photosynthesis and stimulation of H+ efflux result when nonpolar carboxyester compounds enter the cell and generate acidic carboxyl groups when hydrolyzed by esterase enzymes.

Stimulation of H+ Efflux and Inhibition of Photosynthesis by Esters of Carboxylic Acids

Methylparathion modulates lipid biosynthesis in sorghum (Sorghum bicolor L.) Moench

Malathion treatment of the seeds of Vigna sinensis (L), above 50 ppm decreased the seedling growth and respiration rate; it is accompanied by a significant alteration in the activities of different cell wall associated hydrolytic enzymes in the roots of the 72 hour germinated seeds. On the simultaneous application of either of the plant hormones (IAA or GA3) with different concentrations of malathion, it was found that there was a trend to overcome the malathion‐caused inhibition on seedling growth pattern and respiration rate in the roots of the seeds. It was also found that the treatment of the seeds with plant growth hormones, at 100 ppm malathion exposure, helps to restore the normal activities of some cell wall associated hydrolytic enzymes, which showed otherwise significantly altered activities. Above 100 ppm malathion exposure on the seeds, the plant hormones gradually lose their efficiency to counteract the malathion elicited effect on the studied parameters in the roots of the seeds.

Biochemical studies of some cell wall associated enzymes in malathion treated germinating seeds of vigna sinesis (L): Effect of IAA and Ga3 supplementation

Malathion exposure at a concentration above 50 ppm elicited some alteration in the respiratory, swelling and contraction characteristics of mitochondria in the roots of 72 hr germinating seeds of Vigna sinensis (L). Change in these parameters is reflected by seedling growth characteristics of V. sinensis (L). The alteration of mitochondria by malathion (above 50 ppm) is also supported by the experiments which showed a marked leakage of NAD from the intra‐mitochondrial pool and a change in the activities of mitochondrial membrane bound ATPase and acid pyrophosphatase activities. Some change of sterol and phospholipid patterns in the associated mitochondrial membrane are also observed in the roots of the 72 hr germinating seeds of V. sinensis (IS) under malathion exposure (above 50 ppm).

Malathion exposed seeds of Vigna sinensis (L): change in mitochondrial respiration, swelling and contraction, leakage of NAD and mitochondrial membrane bound ATPase and pyrophosphatase activities

Amino acid incorporation into plasma membrane proteins of Vigna sinensis (L) was inhibited by malathion, an organophosphorous insecticide, whereas some stimulatory effect was elicited by plant growth hormones, viz., IAA, GA3 and kinetin. The inhibitory effect of malathion towards amino acid incorporation into plasma membrane proteins was marked at concentrations above 50 ppm, and at 400 ppm the amino acid incorporation was much less. Up to 100 ppm of malathion treatment, the plant growth hormones could counteract the malathion-induced inhibition on amino acid incorporation into plasma membrane protein but above this concentration, the plant hormones gradually lost their effectiveness. Plasma membrane fraction was characterized by studying the activities of enzymes like IDPase, Oligomycin treated ATPase, Cytochrome c-oxidase and glucan synthetase, and also by a sterol/phospho lipid ratio study. From the above studies it appears that glucan synthetase may be the marker enzyme of the plasma membrane of V. si...

The Effect of Malathion on Amino Acid Incorporation into Plasma Membrane Proteins of Vigna sinensis (L): Effect of Plant Growth Hormone Supplementation

S. K. Banerjee

Papers

The Effect of Malathion on Amino Acid Incorporation into Plasma Membrane Proteins of Vigna sinensis (L): Effect of Plant Growth Hormone Supplementation