Composition and enzyme activities of Spiroplasma citri membranes.

Spiroplasma citri was cultured in three different media that supplied cholesterol and fatty acids from: (i) horse serum, (ii) pleuropneumonia-like organism (PPLO) serum fraction, or (iii) bovine serum albumin-fatty acid-cholesterol. The ability of PPLO serum fraction to support growth varied by lot number. Neither PPLO serum fraction nor the bovine serum albumin medium supported growth as well as the horse serum medium. Analysis of cholesterol, lipid phosphorus, and membrane protein showed the horse serum- and PPLO-grown cells to be indistinguishable, but the bovine serum albumin-grown cells were deficient in lipid phosphorus. The three cultures did not show markedly different fatty acid compositions, but, in all cases, the cultures preferentially incorporated palmitic acid and discriminated against linoleic acid. Cultures grown for different times from logarithmic growth through a degenerative phase showed relatively constant ratios of cholesterol/protein and lipid phosphorus/protein. Fatty acid composition was also relatively constant at the different stages. Adenosine triphosphatase and p-nitrophenyl phosphatase were mainly associated with the membrane, whereas reduced nicotinamide adenine dinucleotide oxidase was either readily removed or not associated with the membrane. The reduced nicotinamide adenine dinucleotide oxidase was inactivated at temperatures above 35 degrees C.

Degradation of O, O-dimethyl S-[alpha-(carboethoxy)-benzyl] phosphorodithioate (phenthoate) in soil.

The degradation of ring-labeled 14C-phenthoate in a moist sandy loam and silty clay loam soil was studied. Phenthoate degradation was attributed to the action of extracellular heat-labile soil enzymes which converted to its carbon ester hydrolysis product, phenthoate acid. Thus, rate of phenthoate degradation was greatly retarded in autoclaved soil, but was equally rapid in nonsterile soil under both aerobic and anaerobic conditions. Degradation was also rapid even at a soil treatment of 100 ppm. Phenthoate acid was extensively degraded to 14CO2 by soil organisms under aerobic conditions, but due to unfavorable factors, degraded only by slow first-order kinetics under anaerobic conditions and at the 100 ppm fortification level under aerobic conditions. Phenthoate and phenthoate acid were confirmed as the principal soil components by isolation and identification by IR and NMR data.

The oxidation of parathion to paraoxon. II. By use of ozone.

CONCLUSIONS: Parathion in low concentrations in aqueous solutions can be readily converted to paraoxon in high yield by use of ozone. However, the reaction is not a general one for the production of other oxons from their corresponding organothiophosphorus analogs.