Schistosoma mansoni: killing of transformed schistosomula by the alternative pathway of human complement

The interaction of mechanically transformed schistosomula of Schistosoma mansoni with the alternative pathway of human complement was studied in vitro. To detect early changes in transformation, the schistosomula were prepared at a low temperature and used immediately. As shown previously, freshly transformed schistosomula were highly susceptible to killing by normal human serum and by C4-depleted normal human serum. This serum activity was concentration dependent and was markedly reduced on a twofold serum dilution. Upon incubation at 37 C in defined synthetic medium, schistosomula rapidly became refractory to killing by the alternative pathway of complement. After 1 hr of incubation at 37 C, the percentage of schistosomula which were resistant to killing increased from 16 to 85. This conversion was accompanied by a fivefold decrease in deposition of C3b on schistosomula which had been exposed to 37 C for 1 hr and then further incubated with C4-depleted normal human serum. The following events occurred concomitantly during incubation of freshly transformed schistosomula at 37 C with a half-life of 30-60 min: (1) Decrease in activation and consumption of the alternative pathway of complement by schistosomula; (2) appearance of a strong complement consuming activity in the supernatant of incubating schistosomula; and (3) shedding of protein- and carbohydrate-containing substances from the surface of schistosomula into the supernatant. Isolated external membranes of freshly transformed schistosomula consumed the alternative pathway of complement to a greater extent than membranes of schistosomula preincubated in medium at 37 C. The results demonstrate that transformed schistosomula acquire resistance to complement killing via the alternative pathway by shedding complement-activating substances.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of seed-irradiation on meiosis in M1 plants of Lactuca and related plants

Meiosis was studied in control and seed-irradiated materials of Lactuca sativa, cultivars Tom, Cos and Webbs, L. serriola from the wild, and Cichorium intybus. In meiosis of the M₁ plants from irradiated seed, observations of univalent and multivalent formation, bridge formation at Anaphase I and II, micronucleus formation and persistence, and pollen fertility, were carried out, and compared with controls. Quantitative estimations of bridge formation were made in L. sativa Tom and Cos and in L. serriola, at anaphase I only. It was found that the frequency of anaphase I bridges and reduction of pollen fertility in the M₁ and also M₂ generation, were different for each variety or species; these could be sequenced radiation-resistant to sensitive in the order Tom, Cos and L. serriola.     

A Yersinia pseudotuberculosis protein which cross-reacts with HLA-B27

The most-debated question in the investigation of the spondyloarthropathies has been whether there is molecular mimicry between host HLA-B27 antigens and the arthritis-causing pathogens. We have generated a monoclonal anti-HLA-B27 antibody in our laboratory and have used a radioimmunoassay to screen a panel of bacterial species. Two strains of Yersinia pseudotuberculosis were found to be highly reactive. The cross-reactive Yersinia component was identified by Western blot to be a 19,000 component. A preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis chromatography apparatus was constructed to isolate milligram quantities of this component. To verify that the component carried the HLA-B27-specific epitope, rabbits were hyperimmunized with the purified materials. Affinity-purified antibodies from one of the immunized rabbits indeed carried anti-HLA-B27 activity. Last, antibodies generated against synthetic peptides derived from the HLA-B27.1 amino acid sequence were tested against the Yersinia component. Positive reactivity was found with antibodies generated against a peptide spanning residues 69-83 of the HLA-B27.1 protein. Since this resides in the segment responsible for the allotypic specificity of the antigen, these experiments establish the presence of molecular mimicry to a high degree of confidence.     

The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 1. The experimental model. The radiation loads on animals kept continuously under external and internal radiation exposure in the area of the Chernobyl Atomic Electric Power Station]

Irradiation conditions in which laboratory animals were kept in experimental laboratories of Chernobyl and Kiev after the accident at the Chernobyl A.P.S. are described. The data are presented on the spectral structural and activity of radionuclides in the diet as well as in the organs and tissues of the animals. The radiation loads have been estimated with regard to an external gamma component and the internal one contributed by the incorporated radionuclides. It has been shown that radiation doses received by the animals during their lifetime due to these contributions do not exceed units of cGy.