K. S. Swami

Changes in respiration and ionic content in tissues of freshwater mussel exposed to methyl parathion toxicity.

Oxygen consumption and sodium, potassium and calcium concentration were determined in the freshwater mussel, Lamellidens marginalis, and its tissues during methyl parathion (MP) toxicity. A transient increase followed by decrease in whole animal or tissue respiration as a function of time was observed. Greater loss of calcium by the mantle, sodium by the gill, and calcium and sodium by the hepatopancreas and foot was observed. As compared to calcium and sodium, the loss of potassium by the tissues was less.

The inhibition of sheep liver arginase by some l-amino-acids

Abstract 1. 1. The effects of eighteen common l -amino-acids on sheep liver arginase were studied. Alanine and histidine showed a slight stimulation of the enzyme activity. Ornithine, lysine, leucine, isoleucine, valine, and proline inhibited the enzyme. Other amino-acids were without any significant effect. 2. 2. Inhibition of the enzyme seems to be a property of the carbon chain length of the amino-acids. Ornithinc, lysine, and proline were competitive inhibitors, while valine showed the mixed type inhibition of the unactivated enzyme. 3. 3. Leucine competitively inhibited the unactivatcd enzyme, but snowed mixed-type inhibition of the enzyme activated by pretreatment with Mn 2+ . 4. 4. Isoleucine inhibited the unactivatcd enzyme competitively at high substrate concentrations and non-competitively at low substrate concentrations, suggesting negative heterotropic co-operative effects. 5. 5. These negative co-operative effects of isoleucine, however, were reversed when the enzyme was activated with Mn 2+ . 6. 6. These results suggest that activation of arginase with divalent cations alters the kinetics of inhibition of the enzyme by ammo-acids.

Acid phosphatase activity in the Indian apple snail,Pila globosa (Swainson), during aestivation and starvation stress

Acid phosphatase activity has been studied in hepatopancreas and foot tissues of the Indian apple snail,Pila globosa (Swainson), with reference to aestivation and starvation. The enzyme activity in the tissues of control snails is higher in hepatopancreas, than in foot. The activity of acid phosphatase increased in hepatopancreas and decreased in foot during starvation while it decreased in both the tissues during aestivation. The significance of these findings is discussed.

Glucose metabolism in hepatopancreas and gill of Lamellidens marginallis during methyl parathion toxicity

Abstract Changes in glucose metabolism were studied in hepatopancreas and gill of freshwater mussel, Lamellidens marginalis, exposed to a sublethal concentration (8 ppm) of methyl parathion. A slight decrease in glycogen and pyruvate and an increase in lactate levels were observed. An increase in phosphorylase and aldolase suggested increased formation of trioses during methyl parathion toxicity. The decrease in lactate dehydrogenase activity and increase in lactate content indicated reduced mobilization of pyruvate into the citric acid cycle. Glucose-6-phosphate dehydrogenase activity was increased, suggesting enhanced oxidation of glucose by the HMP shunt pathway. Citric acid cycle enzymes such as isocitrate, succinate, and malate dehydrogenases were found to be decreased, suggesting abnormality in mitochondrial oxidative metabolism as a consequence of methyl parathion toxicity. The decreased cytochrome c oxidase and Mg2+-ATPase, apart from citric acid cycle enzymes, indicated impaired energy synthesis as a result of reduced aerobic oxidation of glycose. The increase in acid and alkaline phosphatase activities suggested enhanced breakdown of phosphate to release energy in view of inhibition of the ATPase system during methyl parathion stress. The changes were more pronounced in hepatopancreas as compared to gill of mussel exposed to methyl parathion.

Neural control of glutamate dehydrogenase activity in the apple snail,Pila globosa (Swainson)

Effects of the three ganglionic extracts viz., cerebral, pleuropedal and visceral ganglia from active and aestivated snails on glutamate dehydrogenase activity in the foot and digestive gland of activePila globosa were studied. The activation with cerebral ganglia was less when compared with visceral and pleuropedal ganglia in foot but in case of digestive gland, the activation reached with cerebral ganglia extract surpassed all other ganglionic effects. The significance of these findings was discussed.

Changes in glutamine levels during starvation and aestivation in the Indian apple snailPila globosa (Swainson)

The glutamine levels in digestive gland, foot and body fluids of normal, starved and aestivatedPila globosa were estimated. Glutamine content was decreased during starvation and aestivation. The percent decrease was more during aestivation than starvation. The decrease may be due to low glutamine-synthetase activity or increased utilization for uric acid synthesis. This may have an adaptive value during aestivation and starvation.

Changes in activity levels of AMP deaminase and adenosine deaminase in the Indian apple snail,Pila globosa (Swainson) during starvation and aestivation stress

Activity levels of AMP deaminase and adenosine deaminase have been studied in hepatopancreas, foot and mantle tissues ofPila globosa with reference to starvation and aestivation. The activity levels of both enzymes were decreased in all the tissues of aestivating snails while in starved animals AMP deaminase activity was increased, in contrast to the decreased adenosine deaminase activity.

Kinetics of Succinic Dehydrogenase Inhibition by Methyl Parathion and its Recovery by Oximes and L-Cysteine in Hepatopancreas of Lamellidens Marginalis

Effects in vitro of methyl parathion on some kinetic constants of succinic dehydrogenase (SDH) in hepatopancreas of freshwater mussel, L. marginalis were studied. Altered pH vs. specific activity curves for SDH demonstrated significant inhibition by methyl parathion in buffered acidic, neutral and alkaline ranges. At high pH ranges IC50 (12.5 microM) of methyl parathion did not cause 50% inhibition enzyme as it did at neutral and acidic pHs. Activation energies (delta E) were found to be increased suggesting decreased efficiency of enzyme in presence of methyl parathion. Non-competitive inhibition with respect to activation by succinate was indicated by decreased maximal velocity (V) without change in Michaelis Menten constant (Km). Pyridine-2-aldoxime (25 microM), pyridine-4-aldoxime (15 microM) and L-cysteine (40 microM) neutralized the inhibition of SDH by methyl parathion (12.5 microM). The kinetic data suggests that inhibition of SDH by methyl parathion was pH and temperature independent.

Electrophoretic Characteristics and Their Relationship to the Enzyme Activities of Subcellular Components in the Amphibian Muscle Fibre (1)

Abstract1. The gastrocnemius muscles of frog were exposed to an electric field of direct current generated by a gradient of 10 volts D. C. per centimeter for 20 minutes in nitrogen environment.2. Activity of marker enzymes such as succinic, malic and glutamic dehydrogenases to locate mitochondria, xanthine oxidase to locate the supernatent protein fraction, and 1-amino acid oxidase to locate the microsomes was studied in the control and experimental muscle halves.3. Both the structural (buffer insoluble) and soluble (TCA insoluble) protein fractions of the fibres were involved in the electromigration.4. Marker enzyme studies indicated that mitochondria and microsomes had a net positive sign of the charge and migrated to the cathode in an electric field of direct current.5. Activity of enzymes was under the influence of either a net positive or negative sign of the charge on the protein content and possibly on the density of charges.

Catalytic potential of arginase in selected tissues of frogRana hexadactyla during chronic starvation

The analytic potential of arginase has been studied in the liver and kidney of frogRana hexadactyla during prolonged starvation. Starvation involves the alterations of Michaelis-Menten constant and the maximal velocity of arginase in both the tissues. Increased activation energy values for the enzymes of both the tissues during starvation indicated decreased catalytic potential.