Biochemical studies on the catalysis of nitrosation by bacteria

Biochemical and microbiological studies were conducted to characterize the mechanism of bacterial formation of N-nitrosomorpholine from morpholine and nitrite at neutral pH. Nitrosating activity was markedly induced when bacteria were cultured anaerobically in minimal culture medium containing nitrate, while the presence of cysteine or tungsten in the medium inhibited induction. Of various metals, coenzymes and inhibitors tested for their effects on in vitro nitrosation of morpholine, potassium cyanide, sodium azide, NAD(P)H and nitrate strongly inhibited nitrosation. Several mutants of Escherichia coli A10 strain were prepared in order to examine whether nitrosation activity is linked to specific loci. Niridazole-resistant mutants, which lack nitroreductase, had as much nitrosating activity as the original E. coli A10, but chlorate-resistant mutants had completely lost this activity. A good correlation was observed between nitrate reductase activity and nitrosating activity in these mutants. These results indicate that bacterial nitrosation is an enzyme-mediated reaction closely associated with molybdenoenzymes such as the nitrate reductase/formate hydrogenlyase system.

Rapid and transient rise in diacylglycerol concentration in Daudi cells exposed to interferon

Human beta-interferon stimulates a 4-fold increase in the concentration of diacyglycerol and a 2-fold increase in the concentration of inositol monophosphate in Daudi (human B-lymphoblastoid) cells within 30 sec of exposure of the cells to interferon. The increase in diacylglycerol and in inositol monophosphate is transient and the concentrations of these compounds decrease to basal levels within 10 min. Preincubation of human beta-interferon with anti-interferon antibodies inhibits this effect as well as the binding of interferon to Daudi cells. Diacylglycerol concentrations were unaffected in mouse A9 cells (fibroblasts) incubated with human beta-interferon and in Daudi cells incubated with human gamma-interferon. Mouse A9 cells are insensitive to human interferon and Daudi cells are insensitive to human gamma-interferon. The magnitude of the increase in diacylglycerol concentration stimulated by interferon can be correlated to the interferon-induced inhibition of Daudi cell division in a dose-responsive manner. Phorbol 12-myristate 13-acetate also inhibits Daudi cell division in a dose-responsive manner. It is likely that the sharp and transient increase in diacylglycerol concentration represents one of the early biochemical changes in Daudi cells exposed to interferon.

Reproducibility of microbial mutagenicity assays: II. Testing of carcinogens and noncarcinogens in Salmonella typhimurium and Escherichia coli

A total of 63 chemicals were tested for mutagenicity in Salmonella typhimurium strains TA98, TA100, TA1535, TA1537, and TA1538, and Escherichia coli WP2 uvrA in a four-laboratory study. Sixty of the chemicals had been tested for carcinogenicity by the National Cancer Institute or the National Toxicology Program. All chemicals were tested for mutagenicity without metabolic activation and with liver S-9 preparations from uninduced and Aroclor 1254-induced F344 rats, B6C3F1 mice, and Syrian hamsters. The intra- and interlaboratory reproducibility of the Salmonella assay with regard to the overall judgment of mutagenic or nonmutagenic was good. The results in the E coli strain, however, exhibited a high degree of variability between laboratories. With one or two exceptions, the mutagens were detected with S-9 preparations from all three species. The uninduced liver S-9 preparations did not activate any chemicals to mutagens that were not also activated by induced S-9, but some chemicals were detected as mutagens only when induced S-9 was used. A positive mutagenic response in Salmonella was predictive of carcinogenicity 69% of the time; when equivocal carcinogens and borderline mutagens were included, the predictivity increased to 83%. Conversely, 76% of the carcinogens were mutagens. When the equivocal carcinogens were included, the proportion dropped to 75%. Relatively few chemicals (18%) were mutagenic in E coli. Not all the carcinogens induced tumors in both rats and mice, and the species-specific carcinogenicity could not be predicted from the S-9-specific mutagenicity.

Serum immunoreactive somatomedin levels in normal adults, pregnant women at term, children at various ages, and children with constitutionally delayed growth

Immunoreactive somatomedin (IRSM) levels in term pregnancy material sera (MS) and newborn cord sera (CS) were higher and lower, respectively, than those in normal adults. IRSM levels in MS and CS were not correlated, suggesting that SM dose not cross the placenta. The similar levels of IRSM in arterial and venous CS suggest that the placenta does not produce SM. IRSM levels in CS were higher than those in newborn sera and were correlated with day 1 newborn sera, suggesting that the placenta may regulate fetal serum IRSM levels. Serum IRSM levels in normal children gradually increased from birth to peak levels at puberty. The mean levels of serum IRSM reached peak levels 2 yr earlier in females. Males near pubertal age with constitutionally delayed growth had lower serum IRSM levels than age-matched controls. Diagnostic measurements of serum IRSM in children requires comparison with age- and sex-matched controls. Serum SM levels may only approximately reflect the local concentrations or activities of SM in various tissues.

A new mutagenic and genotoxic response of the flame retardant tris(2,3-dibromopropyl)phosphate. Activation by singlet oxygen

Illumination of tris (2,3-dibromopropyl)phosphate with visible light in the presence of riboflavin resulted in the formation of a stable product with greatly enhanced genetic and DNA-modifying activities. Because illumination of riboflavin results in the formation of short-lived singlet oxygen, it is assumed that the mutagenic and genotoxic chemical results from a reaction between the flame retardant and singlet oxygen. Since the polluted urban atmosphere is conducive to the generation of this species of oxygen, the present results may, therefore, be relevant to an assessment of the health hazard posed by such an environment.

Dissimilation of the lignin model compound veratrylglycerol-beta-(o-methoxyphenyl) ether by Pseudomonas acidovorans: initial transformations

The initial transformadomonas acidovorans are demethylation of the 4-methoxyl group of the 3,4-dimethoxyphenyl portion of the molecule, and a NAD+-linked dehydrogenation of the benzyl alcohol group. Based on these findings and those described before, an overall degradation scheme is postulated.

Degradation of methoxylated benzoic acids by a Nocardia from a lignin-rich environment: significance to lignin degradation and effect of chloro substituents

Strain A81 of Nocardia corallina hydroxylates or demethylates p-anisic acid to p-hydroxybenzoic acid and isovanillic acid. It demethylates veratric acid to a mixture of vanillic and isovanillic acids. These are both demethylated to protocatechuic acid, which undergoes ring cleavage to afford beta-carboxy-cis-cis-muconic acid. The intermediacy of protocatechuic acid in the catabolic pathway of veratric acid was confirmed by blocking ring cleavage with an additional substituent in the ring: 5-chlorovanillic acid was demethylated to 5-chloro-protocatechuic acid, which accumulated. Chloro substituents in the ring of other methoxylated benzoic acids also arrested their normal metabolism by the Nocardia: an ortho-chloro substituent thwarted both demethylation and ring-opening. ortho-Hydroxylation of p-methoxybenzoic acid to isovanillic acid was unaffected by a chlorine ortho to the methoxyl group. Washed whole cells of veratric acid-grown N. corallina A81 produced no detected structural changes in an isolated lignin. The implications of this observation are discussed.

Bacterial cleavage of an arylglycerol- -aryl ether bond

The first known cleavage by a bacterium of an arylglycerol-beta-aryl ether linkage, the most common intermonomer linkage in lignin, is described.

Cellulases of Thermomonospora fusca and Streptomyces thermodiastaticus

The cellulases of Streptomyces thermodiastaticus (strain 2Sts) and thermomonospora fusca (strain 190Th) were produced with carboxymethyl-cellulose (CMC) serving as the carbon source during growth. Both cellulases act by random internal hydrolysis of the CMC chain, producing cellobiose, glucose, and intermediate length oligosaccharides. Cellobiase was not detected in culture filtrates produced under these conditions.

Defined liquid minimal medium for Caryophanon latum

A defined medium has been developed for the trichome-forming bacterium, Caryophanon latum. Acetate is the main carbon and energy source, and either N-glutamate, or N-NH(4) can be used as the nitrogen source.

Survival, transmission, and taxonomy of Pseudomonas syringae van Hall, the causal organism of bacterial brown spot of bean (Phaseolus vulgaris L.)

Pseudomonas syringae van Hall was shown to be transmitted on seed of bean (Phaseolus vulgaris L.). The pathogen survived in bean field soil until April but not until May. Isolates studied were pathogenic to pea, but not to red clover, white dutch clover, ladino clover, alfalfa, or white lupine. Attempts to isolate P. syringae as a pathogen or as an epiphyte from plants in fence lines and wind breaks surrounding diseased bean fields failed. It was concluded that infected seed is a principal source of the bacterial brown spot pathogen in Wisconsin. Routine bacteriological tests including the utilization of 12 carbohydrates, six organic acids, and 30 other diagnostic tests did not differentiate P. syringae and P. pisi Sackett. These two species differed with respect to acrylamide disc-gel electrophoretic protein patterns, electrophoretic peroxidase isozymes, toxin production, and host range. Isolates of P. syringae produced a toxin with characteristics of syringomycin, whereas isolates of P. pisi did not produce such a toxin.

Qualitative analyses of vegetative cell walls and spore walls of some representative species of Streptomyces

Vegetative cell walls and spore walls of seven Streptomyces species representing four types of spore morphology were qualitatively analysed for their components. Amino acid and carbohydrate components (glucose, glucosamine, muramic acid, diaminopimelic acid, glutamic acid, glycine, alanine, arginine, threonine, valine, leucine, and aspartic acid) in both types of walls were identical in all species. Aspartic acid was a major component in spore walls, but a minor component in vegetative cell walls. Although organic phosphate was present in both vegetative- and spore-wall hydrolysates, the other components of teichoic acid were not found nor was teichoic acid extracted from the isolated walls by cold trichloroacetic acid. A portion of the vegetative cell wall was rendered soluble with lysozyme and separated by paper electrophoresis into two fractions detected with ninhydrin. The lysozyme-resistant portion of the vegetative cell wall showed the same major and minor components as the spore walls, which are also lysozyme resistant.

Clostridium botulinum type E in fish from the Great Lakes

Bott, Thomas L. (University of Wisconsin, Madison), Janet S. Deffner, Elizabeth McCoy, and E. M. Foster. Clostridium botulinum type E in fish from the Great Lakes. J. Bacteriol. 91:919-924. 1966.-The intestinal contents of more than 3,000 fish from Lakes Erie, Superior, Huron, and Michigan were examined for Clostridium botulinum type E. Demonstration of the organism was accomplished by identifying its toxin in liquid cultures inoculated with material from the alimentary tract. Incidence figures, expressed as per cent of the fish tested, were: Lake Erie, 1%; Lake Superior, 1%; Lake Huron, 4%; the main body of Lake Michigan, 9%; and Green Bay (on Lake Michigan), 57%. Thus, C. botulinum type E appears to be widely but unevenly distributed in the Great Lakes, and fish from all areas are potential carriers of it.