摘要:

Analogs of natural bile acid conjugates were incubated with both whole-cell cultures and cell-free extracts of the fungusCercospora melonisCBS 162.60. Those conjugates containing both an α-amino group and a carboxylic acid group in the amino acid moiety were the most susceptible to hydrolysis. Substitution with a β-amino group and (or) a sulfonic acid group greatly reduced the extent of hydrolysis. With all conjugates tested, significant losses of total bile acid were observed on incubation with whole-cell cultures. Two factors have been implicated as contributing to these losses. First, bile acids may be degraded to nonsteroidal products by an inducible enzyme system. Second, bile acids may be bound to mycelia in a manner not reversed by the extraction technique.

ISSN:0008-4166    

DOI:10.1139/m82-069

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Acetylene-reducing bacteria isolated from the setts (stem cuttings used as seed pieces) and roots of two sugar cane varieties propagated aseptically from stem cuttings were identified using a computer-assisted scheme based on 75 biochemical tests. Because 106to 108acetylene-reducing bacteria per gram (fresh weight basis) were found in the roots, while 10 to 100 times fewer were present in the sett, we suggest that the root is the site of bacterial multiplication. Sterilization of the sett surface before planting or root sterilization at harvest reduced or completely removed acetylene-reducing bacteria and associated whole plant acetylene-reducing activity. This indicates that most of the active bacteria were on the sett and root exteriors. Setts did not exhibit acetylene-reducing activity until after emergence of the roots. Since shoot emergence was not necessary for acetylene-reducing activity, the extensive carbohydrate supply of the sett itself must have provided the carbon substrate for bacterial N2fixation. The acetylene-reducing bacteria isolated were facultative anaerobes of the families Enterobacteriaceae and Bacillaceae.Klebsiella pneumoniae,Enterobacter cloacae,Erwinia herbicola, andBacillus polymyxawere present inside the sett and the roots butE.herbicolawas the dominant bacterium on the root exterior. NoBeijerinckiaspp. orAzotobacterspp. were found associated with the sett or the roots.

ISSN:0008-4166    

DOI:10.1139/m82-070

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The furoquinoline alkaloid dictamnine has been shown to provoke lethal damage to filamentous fungi in near ultraviolet light. The phototoxicity was more pronounced againstMucor hiemalisandMucor ramannianusthan againstFusarium graminearumandPenicillium italicum.In vitro, labeled dictamnine was shown to form covalent monoadducts with purified DNA fromM.hiemalisin the presence of long-wave ultraviolet light. Addition of [3H]dictamnine to cultures of the same organism showed photobinding with the fungal DNAin vivo. These results support the suggestion made earlier, on the basis ofin vitroexperiments with calf thymus DNA, that DNA represents a major cellular targetin vivofor the phototoxicity of the alkaloid.

ISSN:0008-4166    

DOI:10.1139/m82-071

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The course of an intranasal infection of Sendai virus in CBA and DBA mice was investigated in animals decomplemented with purified cobra venom factor. The mice were decomplemented either immediately before inoculation or at 4 days postinfection. Depletion of complement after the infection had been established had no apparent effect on the course of the viral infection in the two strains of mice. In contrast, both strains of mice were protected completely from the lethal effects of an infectious dose of 1 LD50of virus when the serum C3 levels were depressed by more than 80% during the early stages of infection. The symptoms of morbidity were less pronounced in these animals and there was a delay in the production of hemagglutination-inhibiting antibody. There was no apparent effect on the growth of the virus in lung tissue. The results suggest that the complement system plays a significant pathogenic role during the course of Sendai virus infections in CBA and DBA mice.

ISSN:0008-4166    

DOI:10.1139/m82-072

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Azospirilla associated with wetland rice were isolated and characterized by employing immunodiffusion and immunofluorescence techniques. Antisera against two strains belonging toAzospirillum lipoferumproduced at least one heat-labile precipitation band with most isolates ofA.lipoferumandA.brasilense. Antisera against two strains belonging toA.lipoferumand one strain belonging toA.brasilenseproduced one band only with strains of their respective species. Fluorescent antibody reactions withAzospirillumwere species specific. Specificity of these antisera and fluorescent antibodies was further demonstrated with bacteria other thanAzospirillum.

ISSN:0008-4166    

DOI:10.1139/m82-073

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Aseptically produced uredospores of race 222 ofPuccinia graminis triticiwere seeded on defined liquid media containing Czapek's minerals, sucrose or glucose, and various combinations and concentrations of 19 amino acids and a tripeptide, glutathione. The cultures were incubated in the dark at 16–17 °C. A medium containing a high concentration of aspartic acid (5988 ppm), cysteine (557 ppm), and glutathione (1014 ppm) supported a profuse growth of the fungus in the form of floating white, fluffy, and vegetative colonies. A sulphur-containing amino acid appears to be essential for the axenic culture of the fungus.

ISSN:0008-4166    

DOI:10.1139/m82-074

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The nature of the diet (pellets, wheat, breakfast bran) ingested by conventional mice influenced the microbial production of indole, β-glucuronidase, urease, and volatile fatty acids in the caecum. We also observed that the nature of the mouse strain influenced the amount of urease activity present in the caecum.

ISSN:0008-4166    

DOI:10.1139/m82-075

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The ultrastructure of a thermophilic methanogenic consortium appearing as morphologically distinct bacterial granules (up to approximately 3 mm in diameter) has been studied. The consortium was enriched and maintained at 60 °C in continuous culture in a defined mineral – vitamin – acetic acid medium at a hydraulic retention time of 44 h. Thin-section electron microscopy showed three morphologically distinct layers of the granules. (1) The outer division zone bears resemblance to a pseudoparenchyma and consists of "macrocysts" and coccoid cells, resemblingMethanosarcinacells. (2) The inner zone is built up of loosely packed ovoid cells and (3) internal cavities containing rods.The cavities were the exclusive site of gas formation, as shown with a specially designed minifermenter allowing direct light microscopic observation of gassing granules. Based on labeling studies with cationic ferritin and scanning electron microscopy a working model for methane formation from acetate by the consortium is presented.

ISSN:0008-4166    

DOI:10.1139/m82-076

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

A procedure was developed to purifyPasteurella multocidaX-73I antigens extracted by potassium thiocyanate. The crude extract was centrifuged at 105 000 × g; the antigens were then separated into a particulate (40p) fraction and a soluble (40s) fraction consisting of proteins and polysaccharides. These fractions were antigenically different.The ultracentrifuged antigens were resolved further by preparative isoelectrofocusing. The 40pantigens focused in a pH range of 3.0 to 6.0; distinctive proteins focused at pH's of 3.5, 3.6, and 3.8. The electrofocused 40pantigens were antigenically similar. The 40santigens were initially electrofocused in a broad pH range and were found within a pH range of 4.4 to 9.0. The process was repeated with a narrower pH range and antigens that were focused in a narrower pH range could be separated and unique antigenic activities identified. Specific antigens from defined pH ranges were pooled and examined further by immunoelectrophoresis, analytical electrofocusing, and sodium dodecyl sulphate – polyacrylamide gel electrophoresis.

ISSN:0008-4166    

DOI:10.1139/m82-077

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The peptidoglycan layer ofDeinococcus radioduransstrain Sark was isolated by centrifugation after digesting broken cells with 2% (w/v) sodium dodecyl sulfate at 43 °C, and sections revealed the characteristic fenestrations (10 nm in diameter). These fenestrations were stained by or filled with 1.0% ammonium molybdate, but were not visible when the isolated peptidoglycan layer was stained with 1.0% uranyl acetate. The fenestrations were not visible when negatively stained with ammonium molybdate after modification of the sacculus by carboxymethylation of free amino groups by treatment with iodoacetate. The surface of the sacculus was smooth when shadowed with carbon–platinum. The isolated layer consisted only of peptidoglycan components. It is concluded that the fenestrations consist of peptidoglycan of different reaction to metal salts and probably enriched in available amino groups.

ISSN:0008-4166    

DOI:10.1139/m82-078

出版商:NRC Research Press    

年代:1982

数据来源: NRC