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Biological sciences

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Construction and analysis of a library for random insertional mutagenesis in Streptococcus pneumoniae: use for recovery of mutants defective in genetic transformation and for identification of essential genes

Article Abstract:

Insertion-duplication mutagenesis (IDM) can identify a high proportion of both dispensable and essential genes. This was found following the construction of a collection of chimeric plasmids with 300-bp inserts, which is both highly complex and highly mutagenic. The mutagenic plasmids were evaluated for size uniformity and randomness of targeted sites by sequencing randomly selected plasmids. Their collective utility as a mutagenic library was investigated by characterizing mutants obtained by integration into the pneumococcal chromosome. IDM was found to be a useful tool for genomic analysis since it hit most known competence genes repeatedly and mutated an additional competence gene previously unidentified via random or specific mutation methods.

Methods, Evaluation, Genetic aspects, DNA probes, Mutagenesis, Streptococcus pneumoniae

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Infection of Acanthamoeba castellanii by Chlamydia pneumoniae

Article Abstract:

The intracellular growth and survival of Chlamydia pneumoniae in Acanthamoeba castellanii was studied by cell culture, immunofluorescence microscopy and electron microscopy. Quantitative determination of chlamydial growth within A. castellanii indicated viable and infective C. pneumoniae in the range of 10000 to 100000 IFU/ml between days 7 and 14 postinfection. There was evidence of infection of the amoebae by C. pneumoniae and that C. pneumoniae entered the typical growth cycle. Findings revealed that amoebae permit the survival of C. pneumoniae.

Chlamydia infections, Chlamydia

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Comparison of free-living amoebae in hot water systems of hospitals with isolates from moist sanitary areas by identifying genera and determining temperature tolerance

Article Abstract:

The hot water systems and moist sanitary areas of six hospitals were contaminated with legionellae and sampled for amoeba. Genus identifications and temperature tolerance analyses were conducted to compare free-living amoebae in hot water systems with isolates from moist sanitary areas. Hartmannella vermiformis was the most common amoeba found to be systemically distributed in hot water systems, where only organisms with high temperature tolerance may survive. Organisms in moist areas colonize at lower temperatures than those in hot water systems.

Health aspects, Hospitals, Legionella pneumophila, Hot water

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