摘要:

Cultures of the mycelial and tissue-like growth phases ofBlastomyces dermatitidis,Paracoccidioides brasiliensis,Histoplasma capsulatum, andSporotrichum Schenckiiwere extracted and oxidized as described by Scholl in 1908. Debye–Scherrer diagrams of the so prepared cell walls show the presence of chitin in both growth phases of each fungus investigated, and give no evidence of the presence of cellulose or another high polymeric substance in the membranes. Nitrogen determinations of the same material corroborate these findings. Electron-microscopic investigations of the isolated chitin ofBlastomyces dermatitidisdid not reveal any substantial difference in the submicroscopic structures of the framework of the mycelial and yeast-like growth phases.

ISSN:0008-4166    

DOI:10.1139/m55-001

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The succinoxidase system ofAspergillus nigerdiffers from that of avian and mammalian tissues in its greater lability during preparation and storage but is similar in its sensitivity to malonate, cyanide, azide, and B.A.L., its association with cell particles, and its single pH optimum at pH 7.3. The system is not inhibited by arsenite in concentrations up to 0.01 M.

ISSN:0008-4166    

DOI:10.1139/m55-002

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Studies on two strains ofL.monocytogenesisolated from human patients, have been reported. The 1949 and the 1951 strains are serologically similar but have slight biochemical variations. Cultures grown at temperatures ranging from 2.8 °C. to 5 °C. showed greater virulence and antigenicity as well as morphological differences when compared with cultures grown at 37 °C. Both the 1949 and 1951 strains were sensitive to penicillin in concentrations between 0.09 to 0.18 and 1.50 to 3.12 units per ml. respectively. They were not sensitive to sulphadiazine or sulphathiazole in concentrations up to 20 mgm. Per ml. Both strains produced an antigenic (lipoid-like) surface substance when extracted with chloroform and ether, which, when injected into rabbits, produced a monocytic response in the peripheral blood. A heat-killed vaccine protected guinea pigs from lethal doses of theListeriaorganism, whereas control guinea pigs injected with the same number of living organisms died with typical symptoms. Partial immunity is demonstrable by the fact that rabbits recovering following penicillin therapy resisted reinfection for a period of at least one hundred and ninety days. Further work is being carried on to determine whether there is a relationship between the heat-labile "L" surface antigen and virulence.

ISSN:0008-4166    

DOI:10.1139/m55-003

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

A study was made of certain factors affecting the use of a phage–plaque-count technique for detecting in bean seed the organism causing common bacterial blight,Xanthomonas phaseoli(Erw. Smith) Dowson. It was found that overgrowth of the fluid test cultures with contaminating bacteria from the seed or from soil did not interfere appreciably with phage adsorption or multiplication in the presence of host cells. Such samples required centrifugation prior to testing in order that plaques might be readily discernible on agar plates. The phage was adsorbed specifically only by cells ofX.phaseoli. Tests with a variety of media showed that nutrient broth was adequate for the purposes of the phage–plaque-count technique. An incubation time of at least 24 hr. for phage and sample was shown to be desirable. Out of 75 samples tested in quadruplicate, 50% were found to be infected with the pathogen in varying degrees. Several samples gave positive reactions by means of this plaque-count method under conditions which were quite unfavorable for isolation of the pathogen by the usual methods.One-step growth studies withX.phaseoli-phage indicated a low order of adsorption, a latent period of 30 to 45 min., a rise period of approximately 30 min., and a burst size of 40 for stationary cultures and 30 for shake cultures. Electron microscopy ofX.phaseoli-phage preparations revealed a particle with a dense head 60 mμ in diameter and a tail 170 to 190 mμ long and 10 to 15 mμ wide.

ISSN:0008-4166    

DOI:10.1139/m55-004

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

A technically simple method of testing the sensitivity of tubercle bacilli to tuberculostatic agents is described which gives accurate results directly from positive sputum in one or two weeks. Parallel slide and tube sensitivity tests against streptomycin and isoniazid on 136 specimens show 49% and 68% agreement respectively. The number of cultures within the sensitive range of each drug was almost identical. The advantages of slide sensitivity testing over conventional methods are technical simplicity and rapid results.

ISSN:0008-4166    

DOI:10.1139/m55-005

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Sucrose-grown (unadapted) and succinate-grown (adapted) cells were mixed with various concentrations of succinate at 3 °C. under air and at 30 °C. under helium. The amount of succinate removed from the external solution by the cells was proportional to the concentration of succinate and did not differ significantly with the two types of cells. Although the data did not differentiate between equilibration with intracellular water and mere adsorption, they indicate that no change has occurred in the surface of the adapted cells to allow a more rapid diffusion of succinate across the osmotic barrier under nonmetabolic conditions. So far as can be determined by using masses of cells, any "permeability" changes during adaptation of the azotobacter cells to succinate must be connected with an active transport process associated with metabolism.

ISSN:0008-4166    

DOI:10.1139/m55-006

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Soil samples, taken by horizons, were obtained from the University of Toronto Forest near Dorset under stands of maple, hemlock, and pine. Counts of bacteria, actinomycetes, and fungi made by the plate method indicated that in general the organic layer contained the largest population, and also that in the organic layer under conifers the fungi exceeded the combined counts of the other two groups, whereas under maple the bacteria predominated. Using the perfusion method, nitrification did not occur to any extent in these forest soil samples except when lime was added, and even then nitrification started very slowly unless a few crumbs of garden soil were added, presumably as a source of active nitrifying bacteria.

ISSN:0008-4166    

DOI:10.1139/m55-007

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

An agar culture method for determining the numbers of methanogenic bacteria in sludge was developed. Hydrogen and carbon dioxide were provided as substrate and palladium as a reduction catalyst. Sodium sulphide could also be used for reducing the medium. A methanogenic organism could be identified by correlating methane production with presence of a particular type of colony which was the most abundant. Fifteen strains which were pure cultured were all similar and were classified asMethanobacterium formicicum. The culture count for methane bacteria in sludge ranged between 105and 108 per ml. The rate of fermentation and the efficiency of conversion of substrate into cell material were studied. Presence of an acetate-fermenting methanogenic organism was established but no pure cultures could be obtained.Methanobacterium formicicumappeared to be the only methane producer growing in the dilution series used for counts.

ISSN:0008-4166    

DOI:10.1139/m55-008

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

No significant serological differences could be detected between the flagella of wild-type cells ofChlamydomonas moewusiiand those of paralyzed mutants.

ISSN:0008-4166    

DOI:10.1139/m55-009

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The nuclei ofGelasinospora tetraspermatravel out of a mycelium of one sex and into one of opposite sex as rapidly as 10.5 mm. per hour. This occurs not only in pairings producing abundant perithecia but also in pairings that produce few or none. The nuclei migrate from cell to cell in a protoplasmic strand running through the center of the hypha. Nuclei have been observed travelling through their own mycelium. They have been seen passing from one cell, through the pore in the transverse septum, into the next cell. The shape and size of the nucleus fluctuates. Spherical nuclei may change to narrow elongate sinuous bodies, and then resume their spherical shape. Nuclei may migrate in an expanded, contracted, or elongate form.

ISSN:0008-4166    

DOI:10.1139/m55-010

出版商:NRC Research Press    

年代:1954

数据来源: NRC