摘要:

Actively growing spherical and rod-shaped cells ofArthrobacter crystallopoieteswere subjected to total starvation in buffer for 8 weeks. At intervals, thin sections of cells were prepared and examined by electron microscopy. Starving cells underwent no morphological changes that would account for their unusual survival capabilities. Cell size and shape remained unaltered. There was no thickening of the cell wall and no development of structures similar to those observed in spores or cysts. As the length of starvation increased, the following changes were observed; glycogen deposits disappeared, the number of ribosome particles decreased, the number of vesicular membranes increased within the cell, and the nucleoplasm expanded in volume to fill the emptying cytoplasm.

ISSN:0008-4166    

DOI:10.1139/m73-001

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

From extracts of a hamster cell line transformed by the Simian virus 40, we have shown the presence of a factor that stimulates the replication of K virus and also counteracts the mechanism of action of interferon. The sensitivity of this factor to a proteolytic enzyme is a possible indication that we are dealing with a protein. This "stimulon" is unrelated to the T antigen as shown by chromatography on Sephadex G-100 and by complement fixation test. Furthermore, at 56 °C, all direct effects on virus K replication are lost but the anti-interferon activity is preserved.

ISSN:0008-4166    

DOI:10.1139/m73-002

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The relationships between the nitrate, nitrite, and oxygen respiratory pathways inAchromobacter fischerihave been studied. The formation of both nitrate and nitrite reductases is inhibited by oxygen. Nitrate and nitrite reductions by the growing cells occur only when the respiratory enzymes are not saturated with oxygen. Nitrite reduction also does not occur so long as there is nitrate in the growth medium. Nitrate is reduced to nitrite which is then reduced to ammonia. The reduction of nitrite with NADH or NADPH requires two enzymes: (a) NAD(P)H – flavin reductase, (b) nitrite reductase, plus the necessary participation of flavin as electron carrier. NAD(P)H – flavin reductase is required only to transfer electrons from NADH or NADPH to flavin, which then transfers electrons to nitrite reductase. The nitrite reductase fromA.fischeriis nonspecific with respect to electron donor since it can use either FMNH2or FADH2. The flavin reductase is also nonspecific with respect to electron donor as it can use both NADH and NADPH.Nitrate metabolism inA.fischeriis unique in that the product of nitrate metabolism is ammonia, but it resembles the respiratory type in other respects.

ISSN:0008-4166    

DOI:10.1139/m73-003

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Six strains of anaerobic rumen bacteria were grown in a rumen fluid medium containing different concentrations of the urease inhibitor, acetohydroxamic acid.Bacteroides succinogenesS85 failed to grow in the presence of 1 × 10−2 Macetohydroxamic acid whereas growth bySelenomonas ruminantiumGA192 was not affected when the initial concentration was 5 × 10−2 M. In cultures of the remaining strains, acetohydroxamic acid extended the lag phase without changing the growth rate in the log phase. The order of decreasing overall sensitivity to acetohydroxamic acid by the strains in terms of growth wasBacteroides succinogenesS85Bacteroides ruminicola23 >Butyrivibrio fibrisolvensD1 ≥Butyrivibriosp. C3>Megasphaera(Peptostreptococcus)elsdeniiB159 >Selenomonas ruminantiumGA192. Washed cell suspensions ofButyrivibrio fibrisolvensD1,Megasphaera elsdeniiB159, andSelenomonas ruminantiumGA192, but of none of the other strains were capable of degrading acetohydroxamic acid. In the presence of 5 × 10−3 Macetohydroxamic acid, the extent of glucose, starch, and xylan fermentation by the strains was modified. The amounts and molar proportions of volatile fatty acids produced from these substrates were also changed. InBacteroides ruminicola23, the presence of acetohydroxamic acid resulted in an 89% reduction in glucose fermentation and a shift in volatile fatty acid production from propionate to acetate.Butyrivibrio fibrisolvensD1 andButyrivibriosp. C3fermented more glucose, but less xylan, when acetohydroxamic acid was present; with glucose as substrate, volatile fatty acid production shifted markedly fromn-butyrate to propionate. The results support the conclusion drawn from previous studies with the mixed rumen microbiota, that the potential effect of the compound upon rumen microbial activities in vivo is not limited to inhibition of urease activity.

ISSN:0008-4166    

DOI:10.1139/m73-004

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The growth of minute virus of mice (MVM) in L cells was followed by plaque assay of both cell-associated and free virus at intervals up to 36 h after infection. The major production of progeny virus occurred after incubation for 27 h and most of the virus remained cell-associated. L cells infected with MVM were pulse-labeled with3H-thymidine for 6 h preceding induction of lysis with sodium dodecylsulfate. Two new species of DNA remained in the supernatant fractions from lysates after selective precipitation by 1 MNaCl of cellular DNA. These first appeared 17 h after infection. On the basis of sedimentation rates and response to heating and to treatment with alkali, one of these species is a hydrogen-bonded duplex molecule, which on denaturation hybridized with the single-stranded DNA of MVM virions.

ISSN:0008-4166    

DOI:10.1139/m73-005

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Two species of marine bacteria with the ability to degrade crude oil were compared ultrastructurally after growing in the presence and absence of oil. Large electron-dense inclusions, which were located predominantly at the cell terminus, characterized species ofFlavobacteriumandBrevibacteriumwhen growing on oil. Cells ofFlavobacteriumsp. had smaller inclusions when grown on marine agar, while inclusion bodies were not found inBrevibacteriumsp. grown on marine agar. Sudan black B staining indicated the inclusions are stored lipids.

ISSN:0008-4166    

DOI:10.1139/m73-006

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Two species ofAchromobacterwere isolated from sewage effluent using biphenyl (BP) andp-chlorobiphenyl (pCB) respectively as sole carbon sources.AchromobacterBP grown on biphenyl accumulated a product with an ultraviolet absorption maximum at 257 nm which could not be identified. Washed cell suspensions of both isolates oxidized biphenyl,o-phenylphenol, phenylpyruvate, catechol,p-chlorobiphenyl,m-chlorobiphenyl,o-chlorobiphenyl,o,o′-dichlorobiphenyl, andp,p′-dichlorobiphenyl. Both isolates producedmetacleavage products by fission of the benzene ring. However, spectral characteristics of degradation products from respective substrates were different between the two isolates, indicating divergent degradation pathways. Benzoic andp-chlorobenzoic acids were produced from the degradation of BP andpCB, respectively, byAchromobacter pCB. Chloride was not produced by either isolate during the degradation of all chlorobiphenyls tested including the growth ofAchromobacter pCB onp-chlorobiphenyl.

ISSN:0008-4166    

DOI:10.1139/m73-007

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

A two-dimensional, steady-state diffusion system has been devised for growth of microorganisms in nutrient concentration gradients. Two reservoirs continually supply substrates, while unused substrates and waste products are washed into a third reservoir. Substrates are supplied in the form of a steady-state gradient within an agar sheet which contains the test organisms. Microbial populations can thus be exposed to all values and combinations of two test variables. The system was tested withEscherichia coligrown in glucose and bicarbonate gradients.Hyphomicrobiumsp.,Rhodomicrobium vannielii, andThiopediasp. in a mixed population were segregated by use of a gradient system of methylamine and sodium sulfide. Exposure of natural aquatic populations to a gradient of pond mud and acetate resulted in differential growth ofBacillussp. and rod-shaped bacteria with terminal endospores. Thus the potential value of gradients in predicting the response of natural microbial communities to nutrients or toxicants and in enriching for specific organisms has been demonstrated qualitatively.

ISSN:0008-4166    

DOI:10.1139/m73-008

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The outer cell-wall layer ofSpirillum serpensVHA, composed of a hexagonal array of macromolecules, was dissociated from 'cleaned' cell-wall fragments with 1.5 Mguanidine hydrochloride, pH 7.0. The soluble material contained 98% protein, 2% carbohydrate, and no ethanolamine, phosphate, RNA, or DNA. Evidence for the homogeneity of the isolated cell-wall protein was obtained by sedimentation velocity, polyacrylamide disc gel electrophoresis, molecular sieve chromatography on Sephadex G-200, and sucrose density gradients. The protein was acidic and had a minimum molecular weight of about 48 000 daltons calculated from the amino acid analysis. A molecular weight of between 125 000 and 150 000 daltons was obtained for the protein by polyacrylamide disc-gel electrophoresis, sucrose density gradients, and molecular sieve chromatography. The sedimentation rate of the protein was considerably less in 1.5 Mguanidine hydrochloride, pH 7.0, than in its absence although the protein remained homogenous under both conditions. Self-assembly of the purified protein into its original hexagonal layer on a template of wall fragments from which the protein had been removed previously was obtained when the mixture was incubated in the presence, but not in the absence of Ca2+. It seems likely that the particles (hexagons) seen on the surface of the cell are an assembly of trimers.

ISSN:0008-4166    

DOI:10.1139/m73-009

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The possibility of enhancing the immunogenicity of human lymphoid cells by infection with vesicular stomatitis virus (V.S.V.) was investigated. V.S.V. infected, purified peripheral human lymphocytes, as well as lymphoblastic cells from the R.P.M.I. series 1788 and 7249, were used to raise antilymphocyte sera in rabbits. The sera were then tested for cytotoxicity and viral neutralization.As compared with uninfected, control lymphoid cells, V.S.V. infection did not enhance the immunogenicity of either type of lymphoid cells. Furthermore, there was no correlation between cytotoxicity and neutralization titers.

ISSN:0008-4166    

DOI:10.1139/m73-010

出版商:NRC Research Press    

年代:1973

数据来源: NRC