摘要:

A mixed culture of bovine rumen microorganisms was incubated anaerobically, under conditions likely to support growth, with added nitrate and in the presence of several potential hydrogen donors known to be intermediates in the rumen fermentation. Reduction of nitrate via nitrite to ammonia was observed but there were marked differences in the relative rates and extent of nitrate and nitrite reduction in the presence of different hydrogen donors. The hydrogen donors were ranked in decreasing order of overall effectiveness for the complete reduction of nitrate and nitrite: formate > hydrogen > glucoselactate > succinate. Methane production in the cultures was markedly depressed in the presence of nitrate. The identification by gas chromatography of nitrous oxide in the gas phase of cultures containing nitrate and incubated with hydrogen, glucose, or lactate showed that the microbiota was capable of denitrification. The quantitative significance of denitrification as a pathway of nitrate dissimilation by rumen microorganisms, however, is probably small.

ISSN:0008-4166    

DOI:10.1139/m72-279

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Numerous hexagonal virus-like particles were detected in, and isolated from, liver and spleen obtained from eight autopsies of human leukemia, diagnosed as different forms of the disease. These particles were purified by a combination of the continuous particle electrophoresis and isopycnic gradient centrifugation. The purified virus-like particles reacted with rabbit antisera produced against the purified particulate antigens of leukemia but not with the extracts obtained from different "normal" human liver and spleen, as examined by the immunodiffusion and immunoferritin techniques. The experimental evidence indicates a biological association of the particulate antigens with human leukemia.

ISSN:0008-4166    

DOI:10.1139/m72-280

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Eight strains ofBordetella pertussislabeled as "phase IV" and received from different laboratories were examined for their cultural, biochemical, and immunological characteristics in comparison with four phase I strains. Five of the strains possessed cultural and biochemical characteristics agreeing with published information on phase IVB.pertussis. Two of the strains had properties more closely resembling those ofBrucella melitensisand one resembledLophomonassp.None of the phase IV strains possessed the protective antigen (PA) or the histamine-sensitizing factor (HSF) and they showed little immunological relationship with one another when tested for agglutination by antisera to phase IV except for L-46, L-51, and L-84, which formed a homogeneous serological group. Certain phase I antisera showed some degree of cross-reactivity with phase IV strains but there was much variation between the individual phase IV strains. Conversely the phase IV antisera cross-reacted with phase I organisms.

ISSN:0008-4166    

DOI:10.1139/m72-281

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Treatment of cells ofSalmonella enteritidiswith ethylenediaminetetraacetate (EDTA) resulted in losses of less than 4% of the total cellular deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein. No lethal effects could be observed when treated cells were plated and counted. The uptake of14C-actinomycin-D,22Na+, and65Zn2+into EDTA-treated cells and the release of65Zn2+from EDTA-treated cell walls were strictly temperature-dependent. The uptake of22Na+and65Zn2+in control and EDTA-treated cells appeared to be enzymatically controlled and could be inhibited byp-chloromercuribenzoate. The uptake and release of these radioisotopes in treated cells was two to five times that of untreated, control cells. The release of lipopolysaccharide could be correlated with a change in permeability of cells when they were treated with EDTA.

ISSN:0008-4166    

DOI:10.1139/m72-282

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A fraction of the cellular DNA of the colonial green algaEudorina elegansstrain 1193 can be specifically labeled with3H-thymidine but not by3H-thymine. Ultraviolet (UV) irradiation ofE.elegansleads to the production of thymine dimers as determined by extraction, hydrolysis, and chromatography of3H-thymidine-labeled cells. Removal of dimers occurs by processes involving visible light (photoreactivation), but dark repair (excision repair) has not been detected in the labeled fraction. A relationship between UV exposure and thymine dimer production has been determined.

ISSN:0008-4166    

DOI:10.1139/m72-283

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Data obtained with the Warburg constant-volume respirometer and from enzyme analysis have demonstrated that the method of regulation of the "hydroaromatic" degradation pathway found inPseudomonas aeruginosais vastly different from that previously discovered inAcinetobacter calcoaceticusand perhaps also significantly different fromP.putida. Two mutants have been analyzed: the first with multiple impairment of degradative abilities; the second with a single defect, i.e. a lack of quinic dehydrogenase activity. Quinic dehydrogenase has also been shown to function for shikimate utilization inP.aeruginosa, even though 5-dehydroshikimate reductase in vitro catalyzes the same reaction. The possible relationship of these findings to pyocyanine formation is discussed.

ISSN:0008-4166    

DOI:10.1139/m72-284

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Photosynthetic characteristics of a purple sulfur bacterium,Chromatium, strain D, cultured under various light intensities were examined. With a decrease in the light intensity used for culture, the bacteriochlorophyllacontent per unit cell nitrogen increased. Also, at low light intensities, the rate of photosynthesis (per unit bacteriochlorophylla) was higher in samples grown under low light than in those grown under high light. These two responses to low light intensity are adaptations that ensure a high photosynthetic rate for the purple sulfur bacterium that usually occurs in a dimly lit environment. Possible chemical and structural mechanisms involved are discussed.

ISSN:0008-4166    

DOI:10.1139/m72-285

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The activities of acid phosphatase and leucine aminopeptidase in brain and liver of yellow fever infected mice were assayed sequentially. It was shown that there was a highly significant activation of both enzymes in the two organs in the course of infection. The activation of enzymes coincided with histopathological expression of the infection. Tissue destruction was more dramatic in the brain than in the liver; although the level of enzyme for each day was higher in the liver than in the brain. In the former there was extensive encephalitis with intensive lytic necrosis of the cortex, while in the latter there was some ballooning of the hepatocytes, but no hepatitis. There was no direct correlation between enzyme activation and the titer of infective virus in the organs.It is suggested that the liver pathology of yellow fever infected mice hitherto regarded as insignificant should be reexamined, since the physiologic injury triggered off by the infection might make itself manifest in the two organs to varying degrees histopathologically.

ISSN:0008-4166    

DOI:10.1139/m72-286

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Protein synthesis by whole cells of two psychrophilic bacteria,Bacillus psychrophilusandBacillus insolitus, directly corresponded to the growth of these organisms at 5, 20 and 30C, with a smaller total amount of growth and protein synthesis occurring at 30C than at 20C. When the effect of temperature on protein synthesis was examined using extracts, the capability to carry out poly U directed incorporation of14C-L-phenylalanine into protein was inhibited by 30C as compared to 5C. The temperature sensitivity of the cell-free protein synthesizing systems was not due to the presence of heat-sensitive aminoacyl-tRNA synthetases. Investigation of the effect of separately heating at 30C washed ribosome (W-RIB) and supernatant (IS-100) fractions prepared from these microorganisms, followed by recombination and reaction at 15C, showed that the temperature sensitivity of the protein synthesis resided in the ribosomal fraction of the cells

ISSN:0008-4166    

DOI:10.1139/m72-287

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Several facultative asymbiotic N2-fixing bacteria exhibited nitrogenase activity when grown in the presence of air and a limiting amount of fixed nitrogen. One isolate (S-4) identified asKlebsiellawas examined in more detail for oxygen effects. Nitrogenase was not detectable in highly aerated submerged cultures but was detectable in shaken and continuous cultures at dissolved oxygen tensions of 3 and 10 mm of Hg respectively. No nitrogenase activity was found in cells from continuous cultures maintained at a dissolved oxygen tension of 15 mm of Hg or above. The nitrogenase activity in whole cells was not oxygen dependent but was oxygen tolerant.

ISSN:0008-4166    

DOI:10.1139/m72-288

出版商:NRC Research Press    

年代:1972

数据来源: NRC