Conversion of 2,4,6-trinitrophenol to a mutagen by Pseudomonas aeruginosa.

A strain of Pseudomonas aeruginosa reduced 2,4,6-trinitrophenol (picric acid) to 2-amino-4,6-dinitrophenol (picramic acid) under anaerobic conditions. Mutagenic assays of picric acid and picramic acid were carried out with histidine-requiring strains of Salmonella typhimurium. Picric acid (10 micrograms per plate) demonstrated mutagenicity (both frame shift and base substitution-gype mutations) only after activation with a rat liver homogenate preparation. Picramic acid (1 microgram per plate) induced both base pair substitution and frame shift-tupe mutations without activation by the rat liver preparation.

Influence of cold or hyperbaric helium-oxygen environments on mouse response to a respiratory viral infection.

In investigating the stress effects of chilling (2-3 degrees C) and hypothermia (2-3 degrees C drop in body core temperature mediated by exposure to hyperbaric helium-oxygen atmosphere) on mouse resistance to "influenza," it was noted that these stresses adversely affected the course of pulmonary infection produced by aerosols of the NWS strain of influenza virus. Comparatively, respiratory LD50 values for control animals were about 25 virus plaque-forming units (PFU) with median mortality occurring on day 13. The LD50 values for mice chilled at 2-3 degrees C were about 15 PFU with median mortality on day 7, and for mice exposed to hyperbaric helium, about 12 PFU with median mortality on day 6. Cold or hyperbaric stress impaired interferon production. Impairment was observed at 24 h but not at 12 h post-challenge and persisted for several days until mice became moribund.

Toxicity and mutagenicity of 2,4,-6-trinitrotoluene and its microbial metabolites.

TNT (2,4,6-trinitrotoluene) of explosive grade is highly toxic to marine forms that included fresh water unicellular green algae (Selenastrum capricornutum), tidepool copepods (Tigriopus californicus), and oyster larvae (Crassostrea gigas), and mutagenic to Salmonella typhimurium. On the basis of mutagenic assays carried out with a set of histidine-requiring strains of the bacterium, TNT was detected as a frameshift mutagen that significantly accelerates the reversion rate of a frameshift tester, TA-98. In contrast, the major microbial metabolites of TNT appeared to be nontoxic and nonmutagenic.

Catecholamine and phagocytic responses in infected mice exposed to hyperbaric helium-oxygen atmospheres.

Exposure of mice to exotic gaseous environments (97% helium and 3% oxygen) maintained at 20% cand 8 ATA (100 psig) increased host susceptibility to aerosol infection with klebsiella pneumoniae. The animals became ill earlier than the controls and the respiratory LD50 for the hyperbaric mice was about 50% smaller than for controls under ambient conditions. Furthermore, hyperbaricity induced an acute depression in phagocytic activity and a marked elevation in the circulating levels of epinephrine, norepinephrine and dopamine.

Metabolic disposition of 2,4,6-trinitrotoluene.

Three pseudomonas-like organisms have been shown to metabolically oxidize 2, 4, 6-trinitrotoluene (TNT). Capability for this oxidative dissimilation varied with each organism. Of the three, isolate "Y" was the most proficient, isolate "I" was less, and isolate "II" was the least. For accelerated TNT degradation, addition of glucose or a nitrogenous substance was essential. Complete dissimilation within 24 h by isolate "Y" cultures supplemented with 0.5% yeast extract is presumed since no TNT was detectable.

Reaction of airborne Rhizobium meliloti to some environmental factors.

Survival of Rhizobium meliloti 102F5 in aerosols at 20 C was maximal at high relative humidity (RH) and minimal at low RH. Relatively high concentrations of NO(2), SO(2), or formaldehyde were needed to significantly reduce viability of R. meliloti in aerosols at 50% RH. Except for the reduction in activity of formaldehyde by SO(2), there was no additive or antagonistic effect of mixing pollutants. High environmental RH enhanced bactericidal activity of NO(2) and SO(2). High RH minimized and low RH accentuated the biological effect of ultraviolet light of 300 to 400 nm wavelength.

Effect of diluent and relative humidity on apparent viability of airborne Pasteurella pestis.

Airborne Pasteurella pestis (A-1122) at low humidities [20 to 50% relative humidity (RH)] exhibited exponential decay when either 1% peptone or Heart Infusion Broth (HIB) was used as the diluent in the viable assay system. At higher RH values (65 and 87%), however, the 1% peptone diluent adversely affected the viability assay. In contrast, HIB as diluent was remarkably effective in demonstrating a higher number of viable cells in aerosols held at high RH values. Similarly, with HIB as diluent, aerosols were shown to contain viable cells during 90 min of observation; with 1% peptone, viability was not detectable after 20 min in the airborne state.