Field and laboratory studies were conducted to assess the survival of cells and spores and plasmid transfer between Bacillus thuringienis strains in aquatic environment. Results indicated that cells and spores of B. thuringiensis can survive for 10 days in water, without altering their number. The sporulation process began after 12-15 hours of inoculation of water. B. thuringiensis was able to transfer conjugative plasmids in the aquatic environment.
Aims: To test the suitability of the Agrobacterium tumefaciens‐mediated transformation (AMT) method with Paecilomyces fumosoroseus, a fungal pathogen that causes diseases in a wide range of insects including whiteflies.
Methods and Results: Conidia of P. fumosoroseus were successfully transformed to hygromycin B resistance using the hph gene of Escherichia coli as the selectable marker. Transformation frequencies were 58·3 ± 18·5, 98·3 ± 24·8 and 169·7 ± 35·5 (±SEM) transformants per 105, 106 and 107 target conidia respectively. After confirmation by PCR, transformants were subjected to Southern analysis, and the results revealed that 45% (four of nine) of the transformants contained single‐copy integration of the T‐DNA.
Conclusions: In our AMT system, we efficiently transformed conidia of P. fumosoroseus. The employment of this method circumvents time‐consuming protoplast preparation and allows the isolation of transformants containing single‐copy integration of the T‐DNA.
Significance and Impact of the Study: Considering the efficiency of Ag. tumefaciens‐mediated transformation, this method represents a useful tool for insertional mutagenesis to characterize genes that are important for the pathogenicity of P. fumosoroseus.
The physiopathogenesis of vulvovaginal candidiasis (VVC) is still not completely elucidated. The objective of this study was to evaluate if there is a relationship between the different genotypes of Candida albicans, their main agent and the virulence of this yeast in vaginal isolates, and to check if there are laboratorial markers that can predict the ability of each isolate to develop VVC independently of symptoms. The production of exoenzymes protease, phospholipase and haemolysin, resistance to hydrogen peroxide, and the genotype were determined. Genotype A was predominant (75%), protease, phospholipase and haemolytic activity were highly expressed, and the majority of the yeasts were sensitive to H2O2 in 1 and 2 hours of exposure, suggesting that these factors are important in the virulence of vaginal isolates. However they did not have any correlation with the genotypes. The different isolates expressed similar virulence potential, suggesting that other factors relating to the yeasts and the host must participate in the development of the clinical disease.
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