摘要:

Sphaerotilus natansdeveloped sheathed filaments in stationary liquid cultures and motile swarm cells in shaken ones. Electron microscopy of negatively stained preparations and thin sections showed that the sheath consists of fibrils. When the filaments were grown in broth with glucose added, the sheath was much thicker and the cells were packed with granules of poly-β-hydroxybutyrate.Swarm cells possess a subpolar tuft of 10 to 30 flagella and a polar organelle which is usually inserted in a lateral position and believed to be ribbon-shaped. The polar organelle consists of an inner layer joined by spokes to an accentuated plasma membrane. The flagellar hook terminates in a basal disk, consisting of two rings, which is connected by a central rod to a second basal disk.

ISSN:0008-4166    

DOI:10.1139/m73-051

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Mouse macrophages in vitro inoculated with a low dose of a cytopathic L cell-grownC.psittaci6BC strain were harvested at times when a delayed cytopathic effect (CPE) was observed by light microscopy and when a cytochemical test for acid phosphatase revealed lysosomal enzyme release. An array of different lysosomal types was revealed by ultrastructural studies such as digestive vesicles with single or double outer membranes and whorls of membranes, dense residual bodies, aggregated and single scattered ferritin-like granules, and fragments of membranes. Enlargement of cysternae of endoplasmic reticulum, disintegration of cytoplasmic organelles, and thinning of ground cytoplasm were also observed. Cytoplasmic degeneration has been observed both within membrane-limited structures and in wider areas not limited by recognizable membranes.A high concentration of the agent resulted in an early toxic effect; this was accompanied by a rapid vacuolization of the cytoplasm of the macrophages which showed a poorly developed ultrastructure, and absence of mitochondria and cytoplasmic organelles. Cytochemical tests indicated that these alterations correlated with release of lysosomal acid phosphatase and disintegration of neutral red stained granules. Ultrastructural studies support the view that disintegration of lysosomes may be considered an important contributory factor in the pathology of chlamydial infection.

ISSN:0008-4166    

DOI:10.1139/m73-052

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

WhenAzotobacter chroococcumgrows on glycolic acid as sole C source, it cannot utilize N2and must be provided with reduced nitrogen. Glycolic acid is metabolized via Kornberg's dicarboxylic acid cycle. The TCA cycle enzymes are low in activity, and isocitric dehydrogenase is absent. It is likely that isocitric dehydrogenase is the source of reductant for nitrogen fixation by Azotobacter nitrogenase.

ISSN:0008-4166    

DOI:10.1139/m73-053

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Alysiella filiformisis commonly found on the epithelial cells of the oral cavity in rabbits. An ultra-structural study of these cells has shownA.filiformisattached by numerous slime appendages (setae) to the host epithelial cells. The organism possesses a multilayered cell wall 18–22 nm thick. Cell division occurs by constriction of the cytoplasm with concurrent septum formation initiating from the dense innermost layer of the cell wall. This is followed by thickening and delamination of the septum with subsequent invagination of the outer layers of the cell wall causing a partial cell separation. However, the cells of the typical trichomes are still held together by septal bridges. Mesosome-like structures were occasionally found and were often in the area of septum formation. All attempts to culture this organism in vitro were unsuccessful.

ISSN:0008-4166    

DOI:10.1139/m73-054

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Thirty eight substituteds-triazine and three dialkyl biguanide analogs were tested for their effects on mycelial growth and the formation of sclerotia bySclerotium rolfsii. None of the chemicals were fungicidal to the organism at a test concentration of 100 μg/ml in potato dextrose agar. One of the chemicals, ipazine, was highly fungistatic, and 11 others demonstrated a significant but lower degree of activity against mycelial growth. The formation of sclerotia was completely inhibited in the presence of only ones-triazine, 2-amino-4-chloro-6-n-propylamino-s-triazine. Eight others-triazines were as active as atrazine, the standard test chemical, in inhibiting the formation of sclerotia, and 10 more of thes-triazines were significantly effective but at a lower level of activity than atrazine. N1,N5-bis(ethyl)biguanide was the only chemical which caused a significant increase in the number of sclerotia formed. No absolute correlation was observed between biological activity and chemical structure although in certain instances there was an apparent correlation between toxicity and the overall electron withdrawing character of the non-alkylamino substituent on thes-triazine ring, or to the steric effects caused by the configuration of the alkylamino substituents. Only those chemicals which were highly active as herbicides were significantly effective in inhibiting mycelial growth and sclerotia formation; however, not all of the herbicidally active compounds were effective in this regard.

ISSN:0008-4166    

DOI:10.1139/m73-055

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

A rough strain ofSalmonella typhimurium, which has a defect in the "inner core" region of its lipopolysaccharide, was shown to release more alkaline phosphatase into the medium during growth than did an isogenic smooth strain of the same organism. The pattern of enzyme release varied during growth in that early logarithmic phase cells retained alkaline phosphatase in their periplasmic space and at their cell surface while cells in later growth phases shed as much as 6% of their content of this enzyme into the medium. The reaction product localization technique used in this study enables us to assess enzyme production and localization in individual cells of a culture. The release of the enzyme was paralleled by a release of lipopolysaccharide from the cells. The released alkaline phosphatase shows a strong tendency to associate with purified phenol-extracted lipopolysaccharide.

ISSN:0008-4166    

DOI:10.1139/m73-056

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Cells refractory to the lethal effect of colicin K were selected from a sensitiveEscherichia coliK-12 strain. They could still be lysed by bacteriophage T6 which is thought to share with colicin K common receptor sites on the bacterial cell wall. Incubation of these cells for 30 min in a colicin K preparation considerably reduced its subsequent activity on the sensitive parent strain. When these tolerant cells were exposed to polymyxin B in the presence of colicin K, the lethal activity of the polymyxin was decreased significantly as compared with that exerted by the antibiotic in the absence of colicin K. In the colicin K sensitive wild strain, the combined lethal effect of the bacteriocin and of the antibiotic was not smaller than that of either inhibitor alone. Examination with the fluorescence microscope of cells stained with acridine orange showed that colicin K tolerant cells incubated with polymyxin B had undergone greater morphological changes than similar cells treated with polymyxin B in the presence of colicin K. Leakage of materials absorbing at 260 nm was greatest for the cells exposed to polymyxin B alone. The results suggest that in colicin K tolerant cells ofE.coliderived from a sensitive strain, the bacteriocin might compete with polymyxin B for sites of attachment on the bacterial cell wall or mask some of the envelope phospholipids which are believed to react with polymyxin B.

ISSN:0008-4166    

DOI:10.1139/m73-057

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Whole-cell extracts ofRhodotorula glutinisgrown on yeast extract – glucose medium contained minute quantities of NAD-dependent alcohol dehydrogenase and cinnamyl alcohol dehydrogenase. Significantly greater quantities of these enzymes, as well as an NADP-dependent alcohol dehydrogenase were contained by cells grown on the same medium with ethanol substituted for glucose as the growth substrate. Although theon ethanol of whole cells grown in ethanol medium was more than triple that of cells grown in glucose medium, there was no significant difference in theon glucose of whole cells grown in glucose or in ethanol medium. Thermal inactivation studies revealed that the NADP-dependent alcohol dehydrogenase was relatively heat-stable as compared with the NAD-dependent alcohol dehydrogenase. Gel column electrophoresis revealed three active bands of alcohol dehydrogenase activity which were identified as NAD-dependent alcohol dehydrogenase, NADP-dependent alcohol dehydrogenase, and cinnamyl alcohol dehydrogenase. The NAD- and NADP-dependent enzymes, particularly the latter, were active on higher alcohols but not on methanol.

ISSN:0008-4166    

DOI:10.1139/m73-058

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

An inducible bacteriocin produced by a strain ofRhizobium trifoliiwas partially purified by ammonium sulfate precipitation and differential centrifugation. Examination of fractions of this material banded in sucrose gradients showed a close correlation between bacteriocin activity and presence of phage-like particles observed by electron microscopy. The particles have a head diameter of about 50 nm and have short tails. Buoyant density of intact particles in cesium chloride was 1.46 g/cm3, as compared with 1.49 g/cm3for a reference rhizobiophage. The apparent nucleoprotein nature of the bacteriocin was confirmed by the ultraviolet absorption spectrum of CsCl-banded material. Double-stranded DNA of density 1.720 g/cm3(compared with 1.716 g/cm3for DNA of the phage) was identified in bacteriocin fractions obtained from CsCl density equilibrium gradients. This density was identical with that of DNA from both induced and noninduced bacterial cells of the producing strain. These characteristics and the inability to reproduce in sensitive bacteria identify the bactericidal agent as a large bacteriocin of the defective phage type. Some apparent differences between this bacteriocin and other, partly characterized bacteriocins ofR.trifoliiare discussed.

ISSN:0008-4166    

DOI:10.1139/m73-059

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Corynebacterium sepedonicumrequires organic sulfur for its growth. In potato host tissue, the normal source of sulfur for the bacterium is methionine. The l isomer is more readily metabolized than the d isomer or the dl racemic mixture, but four derivatives, methionine sulfoxide,DL-methionine-CH3-sulfonium Cl, acetyl- and alanyl-methionine are more efficiently metabolized than any of the methionine isomers. Homocysteine and cystathionine, intermediates in methionine metabolism, are rapidly metabolized in the presence of trace amounts of methionine. Another intermediate, S-adenosylmethionine, has no effect on the bacterial growth. Ethionine and α-methylmethionine are not metabolized byC.sepedonicumand cystathionine or homocysteine cannot overcome the inhibitory effect of α-methylmethionine on growth of the organism.

ISSN:0008-4166    

DOI:10.1139/m73-060

出版商:NRC Research Press    

年代:1973

数据来源: NRC