Influence of water chlorination on the counting of bacteria with DAPI (4',6-diamidino-2-phenylindole)

Article Abstract:

Counting bacteria in drinking water samples by the epifluorescence method after n 4',6-diamidino-2-phenylindole (DAPI) staining is complicated because bacterial fluorescence varies with exposure of the cells to sodium hypochlorite. Escherichia coli laboratory-grown suspension treated with sodium hypochlorite for 90 min was highly fluorescent after DAPI staining. At chlorine concentrations more than 2 mg/ltr, DAPI-stained bacteria had only low fluorescence. Stronger chlorine doses changed the DNA structure, preventing the DAPI from complexing with the DNA. When calf thymus DNA was exposed to sodium hypochlorite, the DNA completely lost the capacity to complex with DAPI.

Analysis, Bacteria, Water, Water treatment

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Seasonal pattern of tomato mosaic tobamovirus infection and concentration in red spruce seedlings

Article Abstract:

Research was conducted to examine the mechanism of tomato mosaic tobamovirus (ToMV) infection in red spruce and the pattern of virus concentration in seedling roots and needles. Enzyme-linke immunosorbent assay was used in testing one-year-old red spruce seedlings obtained from a nursery. Results indicate that ToMV was transmitted by root and not by needle inoculation. Substantial differences in ToMV concentrations in roots were also observed.

Research, Diseases and pests, Spruces, Red spruce, Tobacco mosaic virus

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