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Intravenous infection of cats with feline immunodeficiency virus was used as a model system to study activation of virus replication in brain-resident microglial cells in vitro. Virus release by ramified microglial cells isolated from subclinically infected animals was detectable in cell-free tissue culture supernatant only by reverse transcription and nested PCR of gag-specific RNA sequences and not by virion-associated reverse transcriptase activity. In contrast, cocultivation of in vivo-infected microglial cells with mitogen-activated peripheral blood mononuclear cells (PBMC) regularly allows detection of high virus yields in cell-free tissue culture fluid. Besides uptake and multiplication of microglia-derived virus in PBMC, release of virus from microglia is stimulated by cell contact with PBMC. The data suggest that T lymphocytes patrolling the central nervous system could reactivate the semilatent state of lentiviruses in microglial cells in the course of clinically silent central nervous system infection.

A new method for multilocus enzyme electrophoresis, based on electrophoretic transfers to nitrocellulose after polyacrylamide-agarose gel electrophoresis was explored. Electrophoretic separation was performed on 1-mm-thick slab gels with 6-mul samples of bacterial extracts and was followed by serial 5-min consecutive transfers. The transferability of 19 metabolic enzymes of Klebsiella strains was studied and allowed the simultaneous examination of one enzyme in the separation gel and at least five enzymes on nitrocellulose sheets. The resolution of enzyme bands was increased on nitrocellulose; thus, well-separated bands were recorded for nucleoside phosphorylase, peptidase, and phosphoglucose isomerase whereas their mobility variants could not be clearly distinguished in the separation gel because of stain diffusion. The study of genetic relationships of 42 strains of Klebsiella pneumoniae and 24 strains of Klebsiella oxytoca demonstrated the reliability of the method, since clustering analysis of electrophoretic types, based on electrophoretic polymorphism of 10 metabolic enzymes, showed two main clusters well correlated with the two species. The 57 electrophoretic types described confirm the usefulness of the method for the study of genetic relationships between closely related strains.

Two different mechanisms were responsible for the disappearance of styrene in enrichment cultures: (i) a mixed population of microorganisms, capable of utilizing styrene as a sole carbon source, oxidized this substrate to phenylethanol and phenylacetic acid; (ii) the culture also mediated polymerization of the monomer to low-molecular-weight styrene oligomers. This chemical reaction probably occurred as the result of microbial degradation of butylcatechol, an antioxidant polymerization inhibitor present in commercial styrene. The resultant polymer material was subsequently metabolized. In soil incubation studies, 14CO2 evolution from applied [8-14C] styrene was used to estimate microbial degradation. Approximately 90 percent of the labeled carbon was evolved from a 0.2 percent addition, and about 75 percent was lost from the 0.5 percent application over a 16-week period.

Penicillin-induced filaments of Proteus vulgaris P 18 had a seemingly unaltered cell envelope. Lysozyme, however, reduced the wall part of these filaments into a three-layered structure and caused transformation into spheroplasts. Although cross walls and membrane septa were absent in the filaments, most of the lysozyme-induced spheroplasts remained attached to each other.

After 6 months of incubation in a fertile neutral sandy loam, about 48% of the ring carbons and 2-carbons and 60% of the OCH(3) carbons of specifically labeled coniferyl alcohol had evolved as CO(2). After 1 year, corresponding values were 55 and 65%. When coniferyl alcohol units were linked into model and cornstalk lignins, about 23% of the ring carbons and 2-carbons and 39% of the OCH(3) carbons had evolved as CO(2) after 6 months. After 1 year, corresponding values were about 28 and 46%. The addition of orange leaves (0.5%, wt/wt) after 6 months did not significantly increase the evolution of CO(2). Addition of orange leaves (0.5%, wt/wt) with specifically C-labeled pyrocatechol, coumaryl alcohol, model lignins, humic acid-type phenolic polymers and of uniformly C-labeled fungal melanins did not increase labeled C losses or C losses from the orange leaves. Decomposition of protein and pyrocatechol linked into model humic acid polymers, coniferyl alcohol C in model lignins, and Eurotium echinulatum melanin in six soils varied from 2 to 14%. Significant differences in C losses were related to soils and were not influenced by orange leaf applications.

Photoillumination of tetracycline derivatives with low-intensity (320- to 400-nm) light and visible light generated superoxide, observed as the reduction of ferricytochrome c. The rate of reduction was dependent on the tetracycline concentration and on the derivative being examined, with doxycycline greater than or equal to demeclocycline greater than tetracycline greater than oxytetracycline. Tetracycline-mediated cytochrome c reduction was oxygen dependent and inhibited up to 70% by superoxide dismutase. Illuminated tetracyclines were lethal to Escherichia coli B incubated in a glucose minimal medium containing chloramphenicol. This lethality was light dependent, oxygen dependent, and dependent on the concentration of tetracycline. Kill rates also varied according to the derivative under study, with doxycycline greater than or equal to demeclocycline greater than tetracycline greater than oxytetracycline. The addition of superoxide dismutase and catalase to the incubation medium partially protected E. coli B against the light-dependent lethality. Preinduction of intracellular superoxide dismutase and catalase substantially protected E. coli B against the phototoxicity of tetracyclines. Iron EDTA augmented the phototoxicity of tetracyclines, while diethylenetriaminepentaacetic acid protected against their lethality. Hydroxyl radical scavengers also conferred protection against tetracycline phototoxicity. The extent of protection was in order of the in vitro reactivity of the scavengers with the hydroxyl radical. These results indicate that superoxide, hydrogen peroxide, and the hydroxyl radical are generated by illuminated tetracyclines and are molecular agents of tetracycline phototoxicity in E. coli B.

Martin, J. P. (University of California, Riverside) and S. J. Richards. Decomposition and binding action of a polysaccharide from Chromobacterium violaceum in soil. J. Bacteriol. 85:1288-1294. 1963.-The decomposition rate and binding effect in soil of a polysaccharide from Chromobacterium violaceum was compared with that of a variety of bacterial and plant polysaccharides and more complex organic residues. Most of the polysaccharides tested decomposed more readily than mature plant residues and fungus mycelium. The ease of decomposition varied, however, and polysaccharide from C. violaceum over a period of 1 month was more resistant than corn stalks, Rhodes grass, bean straw, and orange leaves. During the first week, it was as resistant to decay as pine needles. The C. violaceum polysaccharide was more effective in binding or aggregating the soil than all others tested. It also reduced the bulk density of Greenfield sandy loam and increased hydraulic conductivity in neutral soil.