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41.
Delayed hypersensitivity in murine salmonellosis: specificity of footpad reaction in mice infected with rough mutants of Salmonella typhimurium 总被引:1,自引:0,他引:1
Delayed type (footpad) hypersensitivity (DTH) in BALB/c mice immunized with rough mutant strains of Salmonella typhimurium LT2 was examined. Injection of live organisms of an Rb mutant TV148 strain induced DTH in mice, while injection of the heat-killed organisms did not. The mice immunized with live organisms of the Ra, Rb, Rc, Rd, and Re mutant strains showed positive footpad reactions to the heat-killed cell antigen of LT2 (wild type) strain. The mice immunized with the Rb mutant strain also showed positive footpad swellings in response to heat-killed cell antigens of S. paratyphi A, S. paratyphi B, S. typhi, S. enteritidis, and S. cholerae-suis. Furthermore, positive reactions to antigens of Escherichia coli and Shigella flexneri were seen in the TV148-immunized mice, but the mice did not respond to heat-killed organisms of Pseudomonas aeruginosa or Staphylococcus aureus. The cross-reactive footpad reaction to E. coli could be transferred adoptively with T cells prepared from the spleens of TV148-immunized mice into syngeneic recipients. These results suggest that the cross-reactive DTH antigen(s) is widely distributed among related organisms such as Shigella and Escherichia. 相似文献
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Auxotrophic strains of Micromonospora rosaria were isolated by N-methyl-N'-nitro-N'-nitrosoguanidine mutagenesis and used in intraspecific recombination by protoplast fusion. High-frequency fusion of protoplasts of M. rosaria strains was induced by polyethylene glycol (molecular weight, 1,000) (PEG 1,000). The optimum concentration of PEG 1,000 for fusion of M. rosaria was 50% (wt/vol). PEG 4,000 was slightly better than PEG 1,000 at concentrations lower than 50% (wt/vol). The recombinant frequency did not increase after treatment with PEG 1,000 (50% [wt/vol]) for longer than 20 min. Under these conditions, fusion with many auxotrophic strains of M. rosaria resulted in a high frequency of formation of true recombinants (sometimes more than 10%). Additionally, when ros (rosamicin nonproducing) strains were crossed by protoplast fusion; about 5% of the resultant prototrophic recombinants were shown to have the ros+ (rosamicin producing) characteristic restored. Rosamicin production by M. rosaria colonies was clearly distinguished by the broth overlay method. The results of fusion experiments between ros and ros+ strains indicated that either the chromosomal mutation or pleiotrophic effect of some auxotrophic markers is involved. 相似文献
44.
We have used polarized absorbance to observe the process of monomer accretion and polymer alignment which occurs in domains of sickle hemoglobin that are formed and maintained by laser photolysis. These diffusion and alignment processes have been studied as a function of initial concentration and temperature (initial and final), as well as beam size and domain number. Monomers are found to diffuse into growing polymer domains with a rate that is essentially temperature and concentration independent, but which depends on the size of the final domain boundaries, and the number of domains within a boundary. The final concentrations achieved are very close to those found in packed centrifugation experiments (50-55 g/dl) and are approximately independent of starting temperature and concentration. The influx of monomers is accompanied by polymer alignment, and the amount aligned is proportional to the amount diffused throughout the process. We propose that polymer alignment controls the influx of added monomers into the growing domain. 相似文献
45.
Antigenic proteins of 36 and 29 kDa were localized in Spirometra mansoni plerocercoid (sparganum) immunohistochemically by avidin biotin complex (ABC) staining. When polyclonal antibodies such as BALB/c mouse serum immunized with crude saline extract of sparganum or confirmed sparganosis sera were reacted as primary antibodies, the positive chromogen (3-amino, 9-ethylcarbazole) reactions were recognized at syncytial tegument, tegumental cells, muscle and parenchymal cells and lining cells of excretory canals. A monoclonal antibody (MAb) which was reacting to 36 and 29 kDa proteins in the extract of the worm was localized at the syncytial tegument and tegumental cells. The present results suggested that the potent antigenic proteins of 36 and 29 kDa in sparganum were produced at the tegumental cells and transported to the syncytial tegument. 相似文献
46.
Agmatine iminohydrolase (EC 3.5.3.12) was purified to homogeneity from the cytosol of soybean (Glycine max) axes by chromatographic separations on Sephadex G-25, Bio-rex 70, and agmatine-affinity columns. The enzyme was homogeneous by the criteria of analytical gel electrophoresis. Molecular weights estimated by Sephadex G-100 gel and sodium dodecyl sulfate polyacrylamide gel electrophoresis were 70,000, indicating that the soybean axes enzyme is a monomer, in contrast to the dimeric enzymes from corn and rice. The isoelectric point determined by gel electrofocusing was 7.5, higher than that of the corn enzyme (4.7). The optimal pH and temperature for activity were 6.5 and 50 degrees C, respectively. The enzyme has high specificity for agmatine, and the Km for agmatine was 2.5 x 10(-3) molar. The enzyme was sensitive to Cu2+ and also was inhibited by p-hydroxymercuribenzoate. 相似文献
47.
To refine the linkage map of distal mouse Chromosome 12, we have identified DNA restriction fragment variants associated with a creatine kinase gene (Ck-3), the Akt proto-oncogene, an Abelson proviral integration site (D12N1), and the immunoglobulin heavy chain VH3609 variable region family (Igh-V36). The patterns of inheritance of these markers in backcross progeny and recombinant inbred mouse strains allowed their localization with respect to previously mapped genes to yield the linkage map: Aat-15.8 cM-Ck-3-0.9 cM-(Crip, Akt, Igh-C)-0.3 cM-(D12N1, Igh-V). This map confirms genetically the localization of the Igh-V gene complex distal to Igh-C on the chromosome. It differs from previous maps in placing D12N1 distal to Igh-C, and in suggesting that the Igh-V gene complex spans less than one centiMorgan (cM).Other DNA sequence variants detected with the creatine kinase probe allowed definition of four additional genetic loci: Ck-1 near Lmyc-1 on Chromosome 4; Ck-2 between Upg-1 and Hprt-ps1 (D17Rp10) on distal Chromosome 17; Ck-4 near Mpmv-17 and Mls-3 on Chromosome 16; and Ck-5 near Hba on Chromosome 11. 相似文献
48.
Based upon its superior catalytic activity for H2O2 decomposition, a bituminous coal-based activated carbon was selected for investigations of pretreatment and enzyme immobilization methods. Pretreatments considered include acid washing, exposure to strong oxidizing agents, contact with concentrated peroxide solutions, nitration and amination, isothiocyanate derivatization, silanization, and stearic acid coating. Effects of these pretreatments on morphology and trace-metal content of the carbon pellets have been studied using scanning electron microscopy and dispersive analysis of x rays. Immobilization of glucoamylase by adsorption, glutaraldehyde crosslinking, and covalent attachment to carbon activated by water-soluble diimide or diazotization have been examined. These different enzyme-carbon catalysts have been characterized by their enzyme loading, enzyme activity, catalytic activity for H2O2 decomposition, or combinations of these measures of performance. 相似文献
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50.
Kwangho Kim Tae Young Ryu Jinkwon Lee Mi-Young Son Dae-Soo Kim Sang Kyum Kim Hyun-Soo Cho 《Molecules and cells》2022,45(9):622
Colorectal cancer (CRC) has a high mortality rate among cancers worldwide. To reduce this mortality rate, chemotherapy (5-fluorouracil, oxaliplatin, and irinotecan) or targeted therapy (bevacizumab, cetuximab, and panitumumab) has been used to treat CRC. However, due to various side effects and poor responses to CRC treatment, novel therapeutic targets for drug development are needed. In this study, we identified the overexpression of EHMT1 in CRC using RNA sequencing (RNA-seq) data derived from TCGA, and we observed that knocking down EHMT1 expression suppressed cell growth by inducing cell apoptosis in CRC cell lines. In Gene Ontology (GO) term analysis using RNA-seq data, apoptosis-related terms were enriched after EHMT1 knockdown. Moreover, we identified the CHOP gene as a direct target of EHMT1 using a ChIP (chromatin immunoprecipitation) assay with an anti-histone 3 lysine 9 dimethylation (H3K9me2) antibody. Finally, after cotransfection with siEHMT1 and siCHOP, we again confirmed that CHOP-mediated cell apoptosis was induced by EHMT1 knockdown. Our findings reveal that EHMT1 plays a key role in regulating CRC cell apoptosis, suggesting that EHMT1 may be a therapeutic target for the development of cancer inhibitors. 相似文献