Immunochemical properties of naturally occurring antiglobulin factors-homoreactants]

The naturally-occurring antiglobulin factors to the pepsin fragments of the homologous IgG (homoreactants or agglutinins) present in the human and rabbit sera and gamma-globulin preparations, behaved in Sephadex G-200 gelchromatography as proteins with a molecular weight of approximately 250,000 daltons. It was shown that the human pepsin homoreactant failed to penetrate through the placenta. Since the pepsin homoreactant was absorbed specifically by the insolubilized antibodies against the Fc portion of the IgG molecule, the data obtained could indicate that the homoreactant activity was associated with the IgG molecules of the unusual structure.     

Detection of R plasmids in naturally occurring fish-pathogenic bacteria, Edwardsiella tarda.

The conjugative R plasmids were detected from fish-pathogenic Edwardsiella tarda isolated from cultured eels. These R plasmids were resistant to sulfonamide and tetracycline, or sulfonamide, streptomycin, chloramphenicol, tetracycline and kanamycin. There were no inhibitions in growth of phages W-31, P1, T1, T3, T7, and lambda. They were classified into incompatibility group A.     

Tetraoxygenated naturally occurring xanthones

This review, with 350 references, gives information on the chemical study of 234 naturally occurring tetraoxygenated xanthones in 12 families, 53 genus and 182 species of higher plants, and two which are described as fungal and lichen metabolites. The value of these groups of substances in connection with pharmacological activity and therapeutic use of some species is described. The structural formulas of 135 isolated compounds, and their distribution, are also given.     

Detection of cultured and uncultured Burkholderia cepacia complex bacteria naturally occurring in the maize rhizosphere

The species composition of a Burkholderia cepacia complex population naturally occurring in the maize rhizosphere was investigated by using both culture-dependent and culture-independent methods. B. cepacia complex isolates were recovered from maize root slurry on the two selective media Pseudomonas cepacia azelaic acid tryptamine (PCAT) and trypan blue tetracycline (TB-T) and subjected to identification by a combination of restriction fragment length polymorphism (RFLP) analysis and species-specific polymerase chain reaction (PCR) tests of the recA gene. DNA extracted directly from root slurry was examined by means of nested PCR to amplify recA gene with species-specific B. cepacia complex primers and to obtain a library of PCR amplified recA genes. Using the culture-dependent method the species Burkholderia cepacia, Burkholderia cenocepacia, Burkholderia ambifaria and Burkholderia pyrrocinia were identified, whereas using the culture-independent method also the species Burkholderia vietnamiensis was detected. The latter method also allowed us to highlight a higher diversity within the B. cenocepacia species. In fact, by using the culture-independent method the species B. cenocepacia recA lineages IIIA and IIID besides B. cenocepacia recA lineage IIIB were detected. Moreover, higher heterogeneity of recA RFLP patterns was observed among clones assigned to the species B. cenocepacia than among B. cenocepacia isolates from selective media.     

Genotoxicity of naturally occurring hydroxyanthraquinones

A variety of structurally related hydroxyanthraquinones (HA) were investigated in a test battery for the evaluation of mutagenicity and cell-transforming activity. The tests were: (1) the Salmonella typhimurium mutagenicity assay, (2) the V79-HGPRT mutagenicity assay, (3) the DNA-repair induction assay in primary rat hepatocytes and (4) the in vitro transformation of C3H/M2 mouse fibroblasts. In Salmonella, most of the tested compounds were mutagenic in strain TA1537, but only a few were active in other strains. Among these were HA with a hydroxymethyl group, such as lucidin and aloe-emodin. In V79 cells, only HA with 2 hydroxy groups in the 1,3 positions (1,3-DHA, purpurin, emodin) or with a hydroxymethyl sidechain (lucidin and aloe-emodin) were mutagenic. The compounds found to be active in V79 cells were also active in the DNA-repair assay and in the C3H/M2 transformation assay. Thus, it appears that the genotoxicity of HA is dependent on certain structural requirements.     

Radioiodination of naturally occurring phospholipids

A simple and rapid nonenzymatic method for radioiodination of phospholipids is described. It involves oxidation of Na125I with TlCl3 (or chloramine-T) in an aqueous medium, with subsequent exposure of the phospholipids, dissolved in chloroform/methanol, to the action of the oxidizing mixture. Purification of the radiolabelled phospholipids was effected by washing with sodium thiosulphate followed by thin-layer chromatography on silica gel. Specific radioactivity of 125I-labelled phosphatidylcholine was estimated to be about 10 muCi/mg phospholipid. The method is designed for radioiodination of various naturally occurring phospholipids.     

Detergent-shock response in enteric bacteria

Our work on bacterial detergent resistance started with the realization that bacteria growing in a sink full of soap must be resistant to the detergents in that soap. We chose sodium dodecyl sulphate (SDS) as a model detergent and decided to see how much SDS the bacterium growing in the sink could tolerate. The research program thus initiated has shown that bacteria such as Enterobacter cloacae can grow in up to 25% SDS and that SDS-shock proteins constitute c. 8% of the proteins synthesized by SDS-grown Escherichia coli. It has also provided explanations why enteric bacteria are oxidase negative, and how pyrroloquinoline quinone (PQQ) enters the periplasmic space. Finally, for E. coli, it has provided evidence for an alternate, phosphate-limited, aquatic life style which places greater emphasis on the Entner-Doudoroff pathway. Detergent resistance is important both medically and ecologically, e.g. entry of pathogens via bile-salt-containing intestinal tracts and biodegradation of detergent-like pollutants such as those resulting from oil spills. Our current research is focused on SDS-induced modifications of the cytoplasmic membrane and the presence of SDS in the periplasm.     

Dog models of naturally occurring cancer

Studies using dogs provide an ideal solution to the gap in animal models for natural disease and translational medicine. This is evidenced by approximately 400 inherited disorders being characterized in domesticated dogs, most of which are relevant to humans. There are several hundred isolated populations of dogs (breeds) and each has a vastly reduced genetic variation compared with humans; this simplifies disease mapping and pharmacogenomics.?Dogs age five- to eight-fold faster than do humans, share environments with their owners, are usually kept until old age and receive a high level of health care. Farseeing investigators recognized this potential and, over the past decade, have developed the necessary tools and infrastructure to utilize this powerful model of human disease, including the sequencing of the dog genome in 2005. Here, we review the nascent convergence of genetic and translational canine models of spontaneous disease, focusing on cancer.     

Survival of enteric bacteria in seawater

Enteric bacteria exposed to the marine environment simultaneously encounter a variety of abiotic and biotic challenges. Among the former, light appears to be critical in affecting seawater survival; previous growth history plays a major part in preadaptation of the cells, and stationary phase cells are generally more resistant than exponentially growing ones. Predation, mostly by protozoa, is probably the most significant biotic factor. Using Escherichia coli as a model, a surprisingly small number of genes was found that, when mutated, significantly affect seawater sensitivity of this bacterium. Most prominent among those is rpoS, which was also dominant among genes induced upon transfer to seawater.     

Influence of easily degradable naturally occurring carbon substrates on biodegradation of monosubstituted phenols by aquatic bacteria

The influence of readily degradable, naturally occurring carbon substrates on the biodegradation of several monosubstitued phenols (m-cresol, m-aminophenol, p-chlorophenol) was examined. The natural substrate classes used were amino acids, carbohydrates, and fatty acids. Samples of the microbial community from Lake Michie, a mesotrophic reservoir, were adapted to different levels of representatives from each natural substrate class in chemostats. After an extended adaptation period, the ability of the microbial community to degrade the monosubstituted phenols was determined by using a radiolabeled substrate uptake and mineralization method. Several microbiological characteristics of the communities were also measured. Adaptation to increasing concentrations of amino acids, carbohydrates, or fatty acids enhanced the ability of the microbial community to degrade all three phenols. The stimulation was largest for m-cresol and m-aminophenol. The mechanism responsible for the enhancement of monosubstituted phenol metabolism was not clearly identified, but the observation that adaptation to amino acids also increased the biodegradation of glucose and, to a lesser extent, naphthalene suggests a general stimulation of microbial metabolism. This study demonstrates that prior exposure to labile, natural substrates can significantly enhance the ability of aquatic microbial communities to respond to xenobiotics.     

Epidemiology of naturally occurring rotavirus infection in rabbits

The epidemiology of naturally acquired rotavirus infection in commercial rabbitries was studied. Antibody titers to rotavirus were determined by an enzyme linked immunosorbent assay (ELISA). Studies of antibody levels over time within individual rabbit litters and in a colony of rabbits of different ages showed that transplacentally derived maternal antibodies had declined to low levels by about one month of age. More than half of the 88 rabbits 1 to 2 months of age had antibody titers of less than 1/100. All 98 rabbits over 2 months old had titers above 1/100 and 83 had titers over 1/1000. Rotavirus was detected in 25% of diarrheic feces and in 10% of normal feces.