D. Desaiah

A comparison of DDT and its biodegradable analogues tested on ATPase enzymes in cockroach

Abstract Analogues of DDT (ethoxymethyl and methoxymethio derivatives) compared with DDT for their inhibitory action on the ATPase system from tissues of the cockroach, Periplaneta americana show similar, but less inhibitory effects. The mitochondrial (oligomycin-sensitive) Mg2+ ATPase activity from coxal muscle preparations was more sensitive to DDT than the two analogues; whereas, the muscle and nerve cord homogenates showed about equal sensitivity to the biodegradable analogues. The mitochondrial Mg2+ ATPase from nerve cord preparation was more sensitive to the three compounds than the Na+K+ ATPase activity. The significance of these results in relation to recent reports on the effect of DDT on Na+K+ ATPase is discussed.

DDT: Effect of continuous exposure on atpase activity in fish,Pimephales promelas

Fat head minnows, 45-days old, were continuously exposed to DDT using continuous water flow and constant temperature conditions. Exposures were to 0.5 and 2.0 ppb of DDT in water, and combinations of the two concentrations with 50 ppm in food, and 50 ppm in food alone, using C14-DDT in food. Brain homogenates were analyzed for enzyme activity from fish treated for 56, 118, 225, and 266 days; and gill analysis was made at 225 and 226 days exposure. Enzyme reductions were greatest in oligomycin-sensitive (mitochondrial) Mg2+ ATPase, with pronounced effects (over 50% inhibition) at the 266th sampling day. In contrast, Na+-K+ ATPase and oligomycin-insensitive Mg2+ ATPase activities were activated by as much as 28% and 40%, respectively. Mitochondrial Mg2+ ATPase of fish brain has been inhibited to the greatest extent in previously reportedin vitro studies. All three ATPase enzymes were reduced in gill tissue sampled at the 266th day, with mitochondrial Mg2+ ATPase showing the greatest decline.

Inhibition of oligomycin-sensitive and -insensitive magnesium adenosine triphosphatase activity in fish by polychlorinated biphenyls☆☆☆

Abstract Tests in vitro with four polychlorinated biphenyls (PCBs) on four tissues of fish showed prominent inhibitory effects on oligomycin-insensitive Mg 2+ ATPase, with muscle homogenate being most sensitive. Aroclors 1242 and 1254, in the intermediate range of chlorination, were more effective than 1221 and 1268. Mg 2+ ATPase from mitochondria was not as sensitive to the PCBs when compared with DDT-type compounds which were more effective on mitochondrial Mg 2+ ATPase than on oligomycin-insensitive Mg 2+ ATPase. Some stimulation of Mg 2+ ATPase was evident from the poorest inhibitors, Aroclors 1221 and 1268. Na + −K + ATPase from fish brain homogenate was inhibited by Aroclor 1242 but the dose required was several times that for Mg 2+ ATPase.

Inhibition of spider mite ATPases by plictran and three organochlorine acaricides.

Abstract The ATPase enzyme system from two-spotted spider mites, Tetranychus urticae (Koch) was sensitive, in vitro, to four acaricides. Tricyclohexylhydroxytin (PlictranR) was an outstanding inhibitor of oligomycin-sensitive (mitochondrial) Mg2+ATPase from fish brain and spider mite homogenates. The I50 values were 6.6×10−11M and 6.2×10−10M, respectively. Less effective were chlorbenside, chlorfenethol and ovotran. Plictran at a higher concentration (2×10−7M) was also more effective on Na+-K+ATPase both in mites and fish brain homogenates as compared to chlorfenethol, chlorbenside and ovotran. Plictran inhibited oligomycin-insensitive Mg2+ATPase at concentrations of 10−8M but stimulated at high concentrations (5×10−6M and higher).

The in vivo sensitivity of ATPases to DDT, DDE, and physical immobilization in American cockroaches

Abstract American cockroaches injected with sublethal doses of DDT (0.75 μg/roach) at 5-day intervals showed a 40% reduction in oligomycin-sensitive Mg 2+ ATPase from muscle homogenates, and a 23% reduction of Na + -K + ATPase from nerve cords. Thus, the maximum effect measured occurred with the same enzyme and tissue as determined from in vitro studies. The metabolite, DDE, used at 15 μg per roach, gave no significant change in activity of the ATPase system following injection. In contrast, high single doses of DDT (7.5 μg/roach) and 100 μg DDE and dicofol per roach caused over 30% increase in oligomycin-sensitive Mg 2+ ATPase of muscle and a 10–15% increase in Na + -K + ATPase of nerve cords measured 24 and 48 hr later. While a similar response was observed for Mg 2+ ATPase activities in cockroaches that were immobilized, the increase in enzyme activities were much greater than that caused by the pesticides.

The effect of three pyrethroids on ATPases of insects and fish

Abstract 1. 1. Mitochondrial Mg 2+ ATPase from nervous tissue of cockroaches and fish tissues was the most sensitive to 3 pyrethroids, with Dimethrin and Resmethrin giving 50 per cent inhibition with 20 μmoles or less. Bioethanomethrin was least effective. 2. 2. Na + K + ATPase was less sensitive than mitochondrial Mg 2+ ATPase. Muscle ATPases were inhibited less than ATPases from nervous tissue. 3. 3. Oligomycin-insensitive Mg 2+ ATPase was not affected by any of the pyrethroids tested. 4. 4. A possible relationship between the knockdown effect and inhibition of ATPase by the pyrethroids is discussed.

The in vitro sensitivity of fish brain atpases to ogranochlorine acaricides

Abstract Several chlorinated hydrocarbon pesticides, considered to be specific acaricides, were shown to be in vitro inhibitors of the ATPase enzyme system from blue gill fish brain homogenates. Mitochondrial (oligomycin-sensitive) Mg2+ATPase from fish brain was inhibited by each chlorinated bridged biphenyl compound (ovex, chlorberside, chlorobenzilate, 4,4′-dichloro-a-methylbenzhydrol, and 2,4-dichlorophenyl benzenesulfonate). Moreover, these compounds were relatively ineffective on Na+-K+ATPase and the oligomycin-insensitive Mg2+ATPase. In contrast, decachlorobi-2, 4-cyclopentadien-1-yl, a bicyclic pentadienyl compound, inhibited Na+-K+ATPase and oligomycin-insensitive Mg2+ATPase. An alkyl aryl sulfite, 2-(p-tert-butyl-phenoxy)-1-methylethyl 2-chloroethyl sulfite, was relatively ineffective on the ATPase enzyme system. An in vivo correlation, based upon behavior of mites, was shown between the effect on the ATPase system and acaricidal activity.

Inhibition of ATPases by gymnemic acid

Abstract A specially prepared and partially fractionated preparation of gymnemic acid compounds were found to be inhibitory to the ATPase system from housefly brain and labellum, and fish brain. Enzyme activity in a homogenate fraction from labellum showed greatest sensitivity to the gymnemic acid preparation. Na+-K+ ATPase activity from the labellum, which contains the sweet taste sensory receptors, was inhibited by over 92% at a concentration of 4 middot; 10−6M gymnemic acid. Because gymnemic acid compounds are specific suppressants of sweet receptors, the evidence presented in this paper implies that a portion of the ATPase system may be biochemically important in the sweet-sensing mechanism.

Tetradifon (TedionR): A specific inhibitor of Mg2+ dependent mitochondrial adenosine triphosphatase activity☆

Abstract An acaricide, tetradifon (Tedion R ), is a potent inhibitor of mitochondrial Mg 2+ ATPase, 50% inhibition occurring at 5×10 −8 M for a fish brain homogenate preparation. Although the widely used ‘standard’ material, oligomycin, is somewhat more effective on mitochondrial Mg 2+ ATPase, it is less specific than tetradifon to related ATPase enzymes. Tetradifon inhibited less than 20% of Na + K + ATPase over a wide range of concentrations, while oligomycin inhibited about 50% Na + K + ATPase at the concentration which gives nearly complete inhibition of mitochondrial Mg 2+ ATPase in the fish brain preparations.