The virulence-associated factors of Yersinia pestis, which determine the abilities to produce pesticin I (Pst⁺), capsular fraction I antigen (Fra⁺), V and W antigen complex (Vwa⁺) and a cell-surface component for adsorption of exogenous pigments (Pgm⁺), were independently eliminated by cultivation of the cells in the presence of acridine orange, ethidium bromide or sodium dodecyl sulfate at a subinhibitory concentration. A virulent Y. pestis strain, Yreka, harbored at least five extrachromosomal DNA molecules of different sizes. In these molecules, a novel 13-megadalton DNA which was cured concomitantly with the elimination of the Fra factor was found, in addition to the known species of 7 and 44 megadaltons which were lost with the conversions to Pst^- and Vwa^-, respectively. Although the conversion to Pgm^- could not be correlated with the lack of any proper extrachromosomal DNA, the factor was transmitted to Pgm^- cells with the aid of self-conjugative RP4 plasmid. The cells acquiring the Pgm factor regained virulence for mice.

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Studies were conducted to investigate the effect of E. coli endotoxin administration on hepatic triglyceride lipase (H-TGL) activity in rats, since H-TGL activity is known to behave differently from lipoprotein lipase (LPL) activity in various situations. Plasma triglyceride and free fatty acid concentrations were markedly elevated in animals after injection of endotoxin. Cholesterol and phospholipids were also increased significantly. Lipoprotein analysis by ultracentrifugation showed that the most pronounced increase of lipoproteins was in the VLDL and IDL fractions. Triglyceride lipase activities in post-heparin plasma were markedly decreased. A selective assay for H-TGL activity using a specific antibody revealed that this enzyme as well as LPL is significantly decreased (26% of control) in endotoxic animals. Thus, the increase of VLDL and IDL appears to result from the decrease of both of LPL and H-TGL.

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The external shape of the nucleoid of Bacillus subtilis strain w23 was examined with a new electron microscopic technique, the rapid freezing and substitution fixation method. The nucleoid of the log and stationary phase cells was recognized as an area devoid of ribosomes and widely dispersed in the cytoplasm, which was different from that observed in OsO₄-fixed cells. If the bacteria were exposed to low temperatures (0 to 10C), the nucleoid showed a highly concentrated shape in the middle of the cytoplasm. These structural changes were observed only when the bacteria were maintained in a high-salt buffer. The results are discussed in relation to the membrane fluidity at low temperature.

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Numerical analysis of 211 strains of rapidly growing, nonphotochromogenic myeobacteria was carried out by using 116 characters. New species reported after 1981 and not yet compared with known species by numerical classification were included. At the level of 90% of the matching coefficient, the following species could be differentiated from each other and were shown as distinct clusters: Mycobacterium pulveris, M. moriokaense, M. chitae, M. diernhoferi, M. porcinum, M. fortuitum, M. chelonae subspecies chelonae, M. chelonae subspecies abscessus, M. smegmatis, M. agri, M. fallax, M. parafortuitum, M. fortuitum subspecies acetamidolyticum. Four taxa, M. fortuitum, M. porcinum, M. chelonae subsp. chelonae, and M. chelonae subsp. abscessus, were regarded as distinct. However, these were combined into one large cluster at a level of 90% of the matching coefficient and, therefore, were regarded as forming one series or complex. M. fortuitum subsp. acetamidolyticum was reported as a subspecies of M. fortuitum, but this was differentiated clearly from the other species including M. fortuitum.

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IgE antibody responses against Japanese cedar pollen in the mouse were investigated to develop a mouse model of human allergy for combinations of factors including pollen administration routes, elicitation antigens and inbred mouse strains. Daily short term inhalation of native pollen or intratracheal administration of pollen suspended in saline induced IgE antibody responses in DBA/2, BDF₁ and Balb/c mice, but failed to induce any detectable responses in C57BL/6 and C57BL/10 mice. Intraperitoneal injection of pollen suspension also induced IgE antibody responses in DBA/2, BDF₁ and Balb/c mice but not in C57BL, /6 mice. IgE antibody responses against pollen described above were detected by passive cutaneous anaphylaxis (PCA) reactions using crude extract of pollen as an elicitation antigen. On the other hand, IgE antibodies specific for antigen Sugi basic protein (AgSBP), which is a major allergen of pollen in humans (Yasueda, H., Yui, Y., Shimizu, T., and Shida, T., 1983. Isolation and partial characterization of the major allergen from Japanese cedar (Cryptomeria japonica) pollen. J. Allergy Clin. Immunol. 71: 77-86), were also detected by PCA reactions using AgSBP in the sera from mice which received secondary or the tertiary stimulation by pollen. These results suggest that IgE antibody responses against Japanese cedar pollen in the mouse can be induced by airway sensitization and that the responses are genetically controlled by H-2-linked immune response genes. The results also suggest that not only IgE antibody responses specific for components other than AgSBP but also responses specific for AgSBP can be induced in the mouse by repeating appropriate sensitization by pollen.

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Lipopolysaccharide of Salmonella typhimurium was irradiated with gamma radiation at 10, 15, and 30kGy doses. A dose of 30kGy significantly detoxified the LPS (180 times). Mice were injected intraperitoneally with the radiodetoxified LPS, and it was found that it stimulated peritoneal macrophages as was evident from the enhancement of their acid hydrolases and cellular RNA content. Both LPS and radiodetoxified LPS exhibited antitumor activity against S180 cells in Swiss mice. Treatment with 20μg/mouse of either LPS or 30kGy LPS gave maximum survival of the mice (90%). These mice were found to resist the challenge of S180 cells (1×10⁶).

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