摘要:

After sublethal heat treatment ofStaphylococcus aureusS6 at 52C for 15 min in either 0.1 M sodium phosphate (Na cells) or 0.1 M potassium phosphate (K cells), more than 99% of the cells were unable to grow on a medium containing 7.5% NaCl. When placed in H and K medium the survivors recovered their salt tolerance and grew after a lag of 3 h (Na cells) or 5 h (K cells). In the absence of glucose, the total amount of enterotoxin B synthesized by the Na and K cells was similar to the control cells. Addition of 0.1% glucose to the medium increased the total amount of toxin formed by Na, K, and control cells.

ISSN:0008-4166    

DOI:10.1139/m73-238

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Cell envelope membranes were isolated fromPseudomonas aeruginosa. These membranes were resolved into cytoplasmic membrane rich and outer (cell wall) membrane rich fractions by discontinuous sucrose density gradient centrifugation. The resolution was based on the separation of enzyme activities and 2-keto-3-deoxyoctonate. Analysis by gel electrophoresis revealed that two of the three major cell envelope protein components were found in the fraction rich in outer (cell wall) membrane. These two protein components were previously shown to occur in a protein–lipopolysaccharide complex in this microorganism.

ISSN:0008-4166    

DOI:10.1139/m73-239

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Guinea pigs were sensitized toNeisseria meningitidisgroup A by subcutaneous injection of viable meningococci. The animals were skin-tested with heat-killedN.meningitidis, a cell wall preparation ofN.meningitidis, and a soluble somatic antigen prepared from the meningococci. Control skin-test substances included heat-killedNeisseria gonorrhoeae, heat-killedEscherichia coli, purified protein derivative, and Hank's balanced salt solution. Positive 24-h skin reactions, characterized by induration that measured greater than 5 × 5 mm (25 mm2), were produced only by heat-killed meningococci and with the cell wall preparations. The soluble somatic antigen produced only erythema. The meningococci also caused inhibition of migration of macrophages when peritoneal cells from the sensitized guinea pigs were used in the capillary tube MIF test. No inhibition of migration was produced with the control antigens. The delayed hypersensitivity was transferred with viable lymph node cells from the sensitized guinea pigs, but not with dead lymph node cells or with serum. The tests will be used to determine whether rabbits injected intravitreally withN.meningitidisdevelop delayed hypersensitivity.

ISSN:0008-4166    

DOI:10.1139/m73-240

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Conventional transmission electron microscopy (TEM), freeze-etching, and scanning electron microscopy (SEM) were used to study changes in the external morphology ofAzotobacter vinelandiiATCC 12837 during cyst formation. The various methods of cell preparation used for SEM drastically affected the morphology of vegetative and early precystic forms, while little change was observed in the external appearance of late precysts and cysts. SEM preparations from which cyst exine was removed before observation appeared morphologically similar to frozen-etched cells which revealed the central body.

ISSN:0008-4166    

DOI:10.1139/m73-241

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Various organic acids used in standing cultures ofNeurosporaregulate the specific activity of mycelial, repressible alkaline phosphatase. The evidence suggests that the regulatory control occurs primarily through chelation of metal ions which are necessary for the production or stability of the enzyme. Both iron and zinc were needed in the growth medium to produce a maximum enzyme level, while a high copper concentration depressed the enzyme level. Electrophoresis of mycelial extracts on gradient polyacrylamide gels demonstrated that the organic acids and iron do not have these regulatory effects on the repressible or constitutive acid phosphatases ofNeurospora.

ISSN:0008-4166    

DOI:10.1139/m73-242

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Glutamine amide–2-oxoglutarate aminotransferase NAD+oxidoreductase (GOGAT), glutamine synthetase (GS), glutamate dehydrogenase (GD), and alanine dehydrogenase (AD) were studied in soybean root nodules. GS, GOGAT, and AD were present in bacteroids at levels that could account for ammonium assimilation, but GD activity was quite low. The total activities of GS and GD were higher in the cytosol than in the bacteroids by factors of 20 and 7, respectively, whereas GOGAT was not detected in the cytosol. GS (transferase activity) was inhibited by alanine, CTP, glycine, and tryptophan at 5 mM but was relatively unaffected by asparagine, aspartic acid, CMP, glucosamine, and histidine at 5 mM. GOGAT activity was unaffected by ATP, ADP, 8-hydroxyquinoline, and 1,10-phenanthroline but was inhibited by EDTA, citrate, and parachloromercuribenzoate. GOGAT activity (reductive amination) was also inhibited 97% by preincubation with 10−4 M azaserine for 30 min but GD activity was inhibited only 13%. The apparentKmvalues for NH4+by AD was 7.4 × 10−3 M and by GD was 7.3 × 10−2 M while for glutamine by GOGAT it was 9.3 × 10−5 M. Activities and kinetic properties for these enzymes may suggest potential routes of nitrogen assimilation in vivo.

ISSN:0008-4166    

DOI:10.1139/m73-243

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Megasphaera elsdenii, an anaerobic rumen bacterium, produced intracellular polysaccharide granules varying in size from 0.05 to 0.15 μm during growth in batch culture. This polysaccharide material was purified and was found to containD-glucose as the only reducing sugar. The polyglucose polymer was highly opalescent in aqueous solution and formed a strong reddish-brown iodine complex with a maximum absorbance at 493 nm. Its infrared spectrum had characteristic absorption bands at 8.70, 9.25, and 9.75 μm and was identical with that of the glycogen of enteric bacteria and beef liver. When these polysaccharide granules were observed with an electron microscope, they resembled the glycogen granules produced byArthrobacter globiformisandEscherichia coli. These properties indicate that the polysaccharide was a type of glycogen. The yield of crude glycogen was 16.82% of the dry weight of late log-phase cells (14-h).The lysis of cells ofM.elsdeniiand other rumen bacteria that store polysaccharide granules inside the cells, in the rumen of cows fed a feed of fine-particle size (344 μm, geometric mean particle size) and high-energy content, may contribute to the high-carbohydrate level and high viscosity of the cell-free rumen fluid of these cows. Cows fed a coarse feed (519 μm, geometric mean particle size) of the same composition have rumens that contain few bacteria with polysaccharide granules. The cell-free rumen fluid of these cows has low viscosity and low-carbohydrate content.

ISSN:0008-4166    

DOI:10.1139/m73-244

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Complete septa divide the hyphae ofGeotrichum candiduminto many compartments or cells. Two cell types are readily recognizable, (i) the apical cell, delimited by one septum and the surrounding cell wall, and (ii) the sub- or non-apical cell, delimited by two septa and the surrounding cell wall. Vacuolation of the apical cells is slight compared with that of subapical cells. Apical cells contain many vesicles, some of which are elongated and branched, possibly forming an interconnecting tubular network; other vesicles were observed distributed about the apical zone or aggregated to form an apical body (the Spitzenkörper). Vesicles are also evident in subapical cells, but only in association with developing septa. Golgi bodies were not observed in any cells, their function in vesicle production possibly being taken by a modification of part of the endoplasmic reticulum. Both cell types contained mitochondria with contrasting electron-staining properties. Some stages of mitosis were observed. The nucleus appears to retain its envelope throughout division and exhibits intranuclear microtubules attached to spindle plaques. Septa were formed by a centripetal deposition of wall material, plasmodesmata developing during this process. Another deposition of wall material occurs after the centripetal deposition thus allowing a secondary thickening of the septum to take place.

ISSN:0008-4166    

DOI:10.1139/m73-245

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The analysis of 600 samples of topsoil of the Eastern Townships region shows thatClostridium tetaniis present in 53% of those specimens. The high percentage of positivity shows the sensitivity of the technique used and the biochemical analysis of the numerous strains brings out a few characters that are different from those reported in the literature.

ISSN:0008-4166    

DOI:10.1139/m73-246

出版商:NRC Research Press    

年代:1973

数据来源: NRC

ISSN:0008-4166    

DOI:10.1139/m73-247

出版商:NRC Research Press    

年代:1973

数据来源: NRC