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The cytotoxicity of DNA-specific autoantibodies from sera of patients with systemic lupus erythematosis (SLE) and with lymphoproliferative diseases, and from blood of healthy donors was examined on tumor-cell lines L929 and HL-60. DNA-binding IgG fractions from SLE and chronic lymphocytic leukemia (CLL) sera were cytotoxic at concentrations of up to 10(-10) M. No detectable changes in cell viability were observed after incubation with antibodies devoid of DNA-binding activity and DNA-specific antibodies isolated from blood of healthy donors and patients with T-cell lymphoma, B-cell lymphosarcoma, and acute B-cell leukemia. There was good correlation between the cytotoxic activity and DNA-hydrolyzing activity of anti-DNA antibodies. The cytotoxic effect of DNA-binding antibodies presumably was complement-independent, because it was attributed only to the Fab fragment. The cytotoxic effect was completely inhibited by preincubation with double-stranded DNA (dsDNA). Both the cytotoxic effect and the DNA-hydrolyzing activity of anti-DNA antibodies were significantly increased in the antibody fraction that displayed cross-reactivity with nuclear matrix proteins. Possible mechanisms for the formation and pathogenicity of cytotoxic anti-DNA antibodies are discussed in this article.

Comparative study was made of the rhizospheree microbiomes of two cultivars of sorghum (Sorghum bicolor cvs. Sucro 506 and Biomass 133) grown on soils with anthropogenic polyelement anomalies and on a background (control) soil. The study used traditional culture-based and culture-independent metagenomic approaches. In soils contaminated with heavy metals, we found decreased numbers of culturable bacteria and quantitative changes in the populations of actinomycetes and micromycetes. The relative abundance of the families whose members were able to resist heavy metals was found to increase in the rhizospheric communities. The taxonomic profile of the microbial communities at the phylum level did not differ significantly between cultivars. The Shannon diversity and the abundance of actinomycete families in the rhizosphere of cv. Biomass 133were greater than those for cv. Sucro 506. Significant differences were found between cultivars for the number of rhizospheric microorganisms resistant to heavy metals.

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In a long-term model experiment, the abundance dynamics of soil microorganisms was studied as affected by pollution of southern chernozem soils with various concentrations and combinations of iron, nickel and copper ions. In the course of this study, soil microbiocenoses were seeded on solid nutrient media and the following values were estimated: the total numbers of heterotrophic microorganisms on meat–peptone agar, the numbers of iron-oxidizing microorganisms on a selective medium in 0, 30, 90 and 210 days after the introduction of heavy metal ions into the soil. A characteristic diverse impact of heavy metal ions on soil microorganisms was established, and the degree of stability of soil microbocenoses of southern chernozem was revealed. Iron and copper concentrations of 10 and 50 RGCB/MPC in 30 days after soil contamination by individual metal ions or their combinations stimulated the proliferation of heterotrophic microorganisms in the soil microbocenoses and 90 days later the number of this microbial group decreased to the control levels and below. After 210 days, the microbiocenoses returned to a stable state. Nickel ions, introduced into the soil at a concentration of 50 MPC separately and in a number of combinations with other heavy metal ions, did not stimulate the proliferation of heterotrophic microorganisms. Opposite trends were observed in the abundance dynamics of iron-oxidizing microorganisms. With the exception of some model variants such as 10 and 50 MPC of Cu (II), iron, nickel and their combinations in various concentrations inhibited the proliferation of ironoxidizing microorganisms in the first month after soil contamination. The inhibitory effect of a combination of heavy metal ions was stronger than that of individual metals. After 90 days, the numbers of iron-oxidizing microorganisms restored to the control level or even exceeded it. After 210 days, an inhibition of the proliferation of ironoxidizing microorganisms was observed in the microbocenoses, or their abundance corresponded to the value in the control soil sample.