摘要:

Incorporation of tritiated [3H]thymidine byChlamydia psittaci6BC was achieved by growing the parasites in chick embryo yolk sac explants which were exposed to exogenous labeled thymidine. These labeled, purified chlamydiae were next observed by autoradiography within mouse peritoneal macrophages. The number of silver grains remained constant in the cytoplasm of macrophages throughout the developmental cycle of the parasite. The proliferation of labeled chlamydiae in macrophages was confirmed by Giemsa staining and immunofluorescence. Chlamydiae have never been successfully labeled with thymidine in earlier studies when assayed in cultured mammalian fibroblasts. It is suggested that a critical factor in the successful incorporation of thymidine in chlamydiae may be the host–parasite system used.

ISSN:0008-4166    

DOI:10.1139/m76-001

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The allantoic fluid of chick embryos infected withChlamydia psittaciis routinely used as a source of material for the study of the chemical and biological properties of the chlamydiae. We have examined pellets recovered from this allantoic fluid by low- and high-speed centrifugation, as well as high-speed pellets which had been stored at −70 °C, and we find that all of the pleomorphic forms of the chlamydiae are present in these materials. The reticulate bodies and large intermediate bodies are always seen to be morphologically damaged in that their cell envelopes are modified and in that they are distended and occasionally 'leaky.' No morphological evidence of damage was seen in small intermediate bodies or in elementary bodies in any of the materials which were examined. Thus the chlamydial population recovered from the allantoic fluid of infected chick embryos has been modified by selective damage to the least-condensed particles. We propose that the release of lysosomal enzymes from the host cell may coincide with the release of the chlamydia and that these enzymes may be responsible for this selective damage.

ISSN:0008-4166    

DOI:10.1139/m76-002

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The nucleoids of the various pleomorphic forms ofChlamydia psittacihave been examined by direct observation of infected cells and by observations on isolated particles. The fixation and staining methods used were the same as those routinely used for the examination of bacteria to facilitate the comparison of chlamydial fine structure with that of bacteria.The nucleoids of reticulate bodies were composed of fine fibrils which extended throughout these particles. The nucleoids of intermediate bodies are characterized by an electron-dense mass with which the fibrous elements are associated in a structurally coherent manner. As condensation of the intermediate bodies proceeds, the electron-dense mass becomes eccentrically located and the fibers form a distinct radiating structure. Large elementary bodies have a few fibers associated with their condensed electron-dense nucleoids but the more condensed mature elementary bodies have a very discrete and homogeneous electron-dense nucleoid which is separated from the cytoplasmic elements of these particles by a very distinct electron-transparent space. These highly condensed elementary body nucleoids are usually ovoid, but may be elongated or irregular, and a small number of these structures react very strongly with ruthenium red.While the nucleoid structure of reticulate bodies resembles that of the bacterial cell, both the condensation process and the nucleoid morphologies which result from it in intermediate and elementary bodies have no parallels among the bacteria. Thus we conclude that major differences in nucleoid organization exist between the chlamydia and the bacteria.

ISSN:0008-4166    

DOI:10.1139/m76-003

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Lipopolysaccharides were prepared from six organisms by the use of two cell-disruption procedures before conventional phenol–water extraction. Disruption of cells by grinding with glass beads or by digestion with hen egg white lysozyme before phenol extraction facilitated rapid purification and greater yields of lipopolysaccharide. Pretreatment of cells with lysozyme in the presence of ethylenediaminetetraacetic acid was the most efficient method in terms of lipopolysaccharide yield and ease of preparation. Increase in lipopolysaccharide yield achieved by use of the lysozyme method, compared with the conventional phenol extraction, varied from 1.7- to 12.4-fold. Preparations were designated as pure according to several criteria and were judged not to have undergone changes as a result of prephenol extraction procedures.

ISSN:0008-4166    

DOI:10.1139/m76-004

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A simple and rapid procedure to make yeast cells permeable by agitating with toluene–ethanol, (TE) 1:4, v/v was developed. The permeated cells retained their ability to catalyze certain enzyme reactions. Temperature and duration of agitation during TE treatment played an important role in retention of the catalytic potential of permeated cells. Thein situassay using permeated cell preparations was more sensitive even in the absence of added cofactors than the in vitro assay in detecting assimilatory nitrate reductase (NAD(P)H:nitrate oxidoreductase, EC 1.6.6.2) (NAR) activity inCandida utilis.Usingin situassay technique, different mechanisms regulating the biosynthesis of NAR inC.utiliswere investigated. Nitrogen starvation did not lead to derepression of NAR. NO3−ions were absolutely essential for induction and maintenance of high levels of NAR activity. Cells grown on ammonium nitrate possessed relatively lower levels of NAR. Kinetics of NAR induction were followed as a function of time and inducer concentration. The influence of various cations on the induction of NAR by nitrate was investigated. A wide range ofD-amino acids induced NAR synthesis. Of 22L-amino acids tested only phenylalanine induced significant levels of NAR. Various intermediates of the pathway of nitrate reduction influenced the rate of NAR induction. There was a rapid disappearance of in vivo activity of the enzyme of induced yeast cells on nitrogen starvation, and the rate of loss was accelerated by the presence of NH4+.

ISSN:0008-4166    

DOI:10.1139/m76-005

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Previous methods of performing aquatic acetylene-reduction assays are described and several problems associated with them are discussed. A refinement of these older techniques is introduced and problems that it overcomes are also discussed. A depth profile of nitrogen fixation (C2H4production), obtained by the refined technique, is shown for a fertilized Canadian Shield lake in the Experimental Lakes Area of northwestern Ontario.

ISSN:0008-4166    

DOI:10.1139/m76-006

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Several probes for measuring dissolved carbon dioxide (CO2) concentration were installed in a 68-litre fermentor and their effectiveness compared. Submerged silastic rubber tubing gave reproducible results over a wide range of operating conditions and was generally superior to all other probes evaluated.The silastic rubber probe was used to compare the partial pressure of CO2in viscous fermentation media with that in the fermentor exhaust gas. No significant difference was found.Results show that determination of the CO2partial pressure in the exhaust gas gives an excellent approximation of the partial pressure of dissolved CO2in the liquid medium, eliminating the need for measurement of CO2concentration in the broth.

ISSN:0008-4166    

DOI:10.1139/m76-007

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Purified influenza virus contains ribonuclease activity. The enzyme does not hydrolyze viral RNA but both 28 S and 18 S host cell RNA are degraded forming large (about 16 S) and small (about 5 S) fragments with the release of the acid-soluble material.It has an optimum temperature of 37 °C, requires no divalent ions, and is inhibited by 0.1 MEDTA and 1% SDS. Treatment with 4 Murea increases enzymatic activity considerably (42%) but is not a prerequisite for eliciting ribonuclease activity suggesting that the enzyme is probably located near the surface of the virus particle. Results show that the observed enzyme activity is virus-associated as no host cell protein is detectable in the purified virus.

ISSN:0008-4166    

DOI:10.1139/m76-008

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Scanning electron stereoscopy and transmission electron microscopy were used to correlate morphological alterations and cytological phenomena associated with deterioration of arbuscules in yellow poplar mycorrhizae. Arbuscular degradation was initiated at the tips of the finest branches and progressed basipetally. Cytoplasm in arbuscular hyphae progressively deteriorated and was followed by collapse of the fungal walls. Degraded portions of the arbuscules aggregated into clumps comprised of host wall material and the distorted fungal walls. Host nuclei, abundant mitochondria, and proplastids were closely associated with arbuscular branches undergoing cytoplasmic deterioration and with clumped portions of the arbuscule which contained degraded hyphal branches. Most of the arbuscules observed had deteriorated to the clumped stage. Some cortical cells contained several clumped arbuscules and nearly mature, intact arbuscules which indicated that reinfection occurs even as degradative phenomena are in progress. It is suggested that substantial quantities of mineral nutrients may be made available to the host via degradation of fungal cytoplasm in the arbuscular hyphae preceding aggregation of degraded hyphae into discrete clumps.

ISSN:0008-4166    

DOI:10.1139/m76-009

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A microbiological assay method has been developed and applied toNeisseria gonorrhoeae, for the purpose of detecting enzymatic deactivation of benzyl penicillin. Calibration of the method, using strains ofEscherichia coliK-12 with previously reported penicillinase (EC 3.5.2.6.) activities, has shown that it is extremely sensitive and may be used in a quantitative manner. At the limit of sensitivity the test is able to detect penicillin breakdown in the order of 3 × 10−3 μg in 48 h, which is equivalent to about 7 × 10−8 μmol/min per milligram dry weight of cells. Over 100 strains ofN.gonorrhoeae, most of them resistant to penicillin, were screened for their ability to deactivate penicillin during 48 h of growth in the presence of subinhibitory levels. No deactivation was detected. It is concluded, from quantitative evidence, that reduced penicillin sensitivity inN.gonorrhoeaeis not due to the enzymatic deactivation of the antibiotic.

ISSN:0008-4166    

DOI:10.1139/m76-010

出版商:NRC Research Press    

年代:1976

数据来源: NRC