Detoxification of AM-241 solutions by humic substances: bioluminescent monitoring.

The study addresses the effect of humic substances on marine luminous bacteria Photobacterium phosphoreum exposed to Am-241 (3,000 Bq L(-1), water solution). Luminescent intensity of the bacteria was applied as a marker of their physiological activity. Humic substances have been found to reduce the effect of Am-241 on luminescence, decrease damage to cells, and change distribution of Am-241 between bacterial cells and intercellular media. It was shown that water-soluble humic substances, being products of natural transformation of organic substances in soil and bottom sediments, can serve as protecting agents for water microorganisms exposed to alpha radionuclides.

Observations on morphologic and genetic diversity in populations of Filoboletus manipularis (Fungi: Mycenaceae) in southern Viet Nam.

The morphological variation of basidiomata of Filoboletus manipularis (Berk) Singer collected in southern Viet Nam was studied. Phylogenetic analyses comprising three gene loci indicated that these collections, although exhibiting widely varying morphologies, represented a single species with a population composed of genetically diverse, sexually compatible monokaryon parental strains. No correlation was found between any aspect of morphological variation and intraspecific phylogenetic patterns for the three gene loci studied. Primers were designed to amplify the intron-rich 5' region of the translation elongation factor 1-α gene (tef1α) and amplicons cloned and sequenced to characterize the parental haplotypes for individual basidiomata. The presence of recombination over the entire morphological diversity seen was confirmed by split decomposition analysis and analysis of gene diversity indicated a lack of allelic fixation within local populations. On several occasions, more than two apparent parental haplotypes were characterized from individual basidiomata, indicating that at least some basidiomata are chimeric or otherwise develop from a multinucleate condition. The literature supporting our observations of the occurrence of multinucleate basidiomata is reviewed and possible mechanisms for this phenomenon are proposed.

Effect of low-level alpha-radiation on bioluminescent assay systems of various complexity.

This study addresses the effects of low-level alpha-radiation on bioluminescent assay systems of different levels of organization: in vivo and in vitro. Three bioluminescent assay systems are used: intact bacteria, lyophilized bacteria, and bioluminescent system of coupled enzyme reactions. Solutions of 241Am(NO3)3 are used as a source of alpha-radiation. It has been shown that activation processes predominate in all the three bioluminescent assay systems subjected to short-term exposure (20-55 h) and inhibition processes in the systems subjected to longer-term exposure to radiation. It has been found that these effects are caused by the radiation component of 241Am3+ impact. The intensity of the 241Am3+ effect on the bioluminescent assay systems has been shown to depend on the 241Am3+ concentration, level of organization and integrity of the bioluminescent assay system. The bioluminescent assay systems in vivo have been found to be highly sensitive to 241Am3+ (up to 10(-17) M).