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Identification of pathogenic Leishmania promastigotes by DNA: DNA hybridization with kinetoplast DNA cloned into E. coli plasmids.

We report the characterization of Leishmania (L. infantum, L. donovani, and L. major) kinetoplast DNA (kDNA) by the use of restriction endonuclease digestion patterns and Southern hybridizations. Overall, the sizes and fragment patterns of MspI restriction endonuclease-produced DNA fragments vary from species to species. However, kDNA isolates from different species and strains cross-reacted to a great extent in Southern hybridization experiments. Only kDNA isolated from L. infantum and L. major had little homology during hybridization reactions. To prepare DNA probes that would differentiate between species of Leishmania, minicircle kDNA was digested with restriction enzymes and ligated to an E. coli plasmid. Several plasmids were isolated that specifically detect in hybridization experiments as few as 5 X 10(3) L. donovani or L. infantum promastigotes lysed on nitrocellulose filters.

Animals↗

Identification of pathogenic T cells in patients with beryllium-induced lung disease.

Chronic beryllium disease (CBD) is caused by beryllium exposure and is characterized by granulomatous inflammation with accumulation of CD4+ T cells in the lung. We analyzed TCR beta-chain and alpha-chain genes expressed by these CD4+ T cells. In the lungs of individual patients, as well as among four of five CBD patients studied, different oligoclonal expansions within the Vbeta3 subset were found to express homologous or even identical CDR3 amino acid sequences. These related expansions were specific for CBD patients, were compartmentalized to lung, and persisted at high frequency in patients with active disease. Limiting dilution cloning and analysis of coexpressed TCR alpha-chain genes confirmed that these TCRs were selectively expanded by a common Ag involving beryllium. Overall, homologous TCR beta- and alpha-chains showed identical V regions and invariant charged residues within the CDR3 but considerable variability in TCRJ usage. Remarkably, CBD patients expressing nearly identical TCRs did not share common HLA-DRB1 or DQ alleles. These results implicate particular CD4+ cells in the pathogenesis of CBD and provide insight into how beryllium is recognized in human disease.

Amino Acid Sequence↗

REMI mutagenesis and identification of pathogenic mutants in blast fungus (Magnaporthe grisea).

Blast fungus' mutant, which is very difficult to obtain, is the key substance in the study of the relation between pathogen and plant. Rice-Aichi-ashahi was used as the host and plasmid pBF101 or pCSN43 as foreign DNA fragment, and REMI mutagenesis was applied to tag the pathogenic sequence in rice blast fungus M.grisea. Three mutants (R2H65, R2H69 and R2B1565) related to pathogenicity were recovered from several hundreds of transformants. R2H69 and R2H65 produced merely strange conidia which could not form appressorium or yield abnormals, and pathogenicity test further confirmed that they were unable to cause disease. R2B1565 possesses the same phenotypes as those of the wild type except that the ability of causing disease was much reduced.

DNA Restriction Enzymes↗

[Evaluation of the lysozyme and DNAase activity for the identification of pathogenic staphylococci].

The sensitivity of two tests recently proposed for the classification of pathogen staphylococci were evaluated: --production of DNA-ase with the modified method of Lachica et al.; --production of lisozyme. The two above tests were studied with other six tests on 1,000 strains of staphylococci showing a very high specificity. The Authors propose that the DNA-ase production and the lisozyme production, also for their very simple execution, should become routine tests to identify the strains of pathogenic staphylococci.

Deoxyribonucleases↗

[The isolation and identification of pathogenic bacteria from rampant caries in children].

OBJECTIVE: In order to prevent rampant caries in children, the predominant pathogenic bacteria of rampant caries in children were defined. METHODS: The pathogenic bacteria of rampant caries were isolated and identified in 30 children with rampant caries, aged from 2 to 5 years old. Samples were collected from the caries of labial surfaces of maxillary anterior deciduous teeth, including caries lesions and caries-free smooth enamel surfaces. Plaque were obtained from the cervical third areas of the maxillary labial anterior deciduous tooth surfaces in children without rampant caries and caries-free children and served as controls respectively. The isolates were identified by colony morphology, biochemical tests and DNA base contents (mol percent G + C). RESULTS: The prevalence of Streptococcus mutans (S. mutans) and Streptococcus sobrinus (S. sobrinus) in the plaque of caries lesions and the proportions of S. mutans and S. sobrinus in the plaque of 2 sampling sites of children with rampant caries were all significantly higher than those of children without rampant caries and caries-free children (P < 0.05). CONCLUSION: S. mutans and S. sobrinus are predominant pathogenic bacteria in rampant caries in children.

Child↗