摘要:

The physical and nutritional requirements for growth ofHexamita inflatahave been studied in axenic cultures. The flagellate was capable of growing over a wide range of temperature (5 °C to 25 °C), of hydrogen ion concentration (pH 4.5 to 8.5), and of salinity (3 to 28‰); and required a reducing or anaerobic environment. The requirement of an egg-yolk suspension for growth was partially satisfied by unsaturated fatty acids. Attempts to replace the peptone by mixtures of amino acids were not successful. A simple medium containing a vitamin mixture, linoleic acid, glucose, cysteine, peptone, and salt has been formulated.

ISSN:0008-4166    

DOI:10.1139/m68-139

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Cells of two strains ofLactobacillus caseiincubated for 2–10 h in the presence of tetranitro-blue tetrazolium (TNBT) and mannitol were studied in electron micrographs of ultrathin sections. The reduction product tetranitro-blue diformazan (TNBF) was found to be predominantly associated with the plasma membrane and its derivatives. Untreated cells (normal control), as well as cells incubated with mannitol in absence of TNBT (dye control), or with omission of mannitol (substrate control) displayed ultrastructural characteristics, in general, similar to those previously reported for other Gram-positive bacilli, particularlyLactobacillusspecies.

ISSN:0008-4166    

DOI:10.1139/m68-140

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

AlthoughLactobacillus caseiis generally considered to be "indifferent" to oxygen, several strains exhibited considerable respiratory activity with a number of substrates related to carbohydrate catabolism. In many cases this respiratory ability enables the organism to utilize energy sources that would be unavailable under anaerobic conditions. The chief features of respiration ofL.caseistrain 103 were fairly representative of those examined.(N) values of this strain on glucose ranged from 75 to 200 and with mannitol from 250 to 500. This respiration was insensitive to 1.7 mMKCN and the rate of oxygen consumption was independent of oxygen concentration from ca. 500 μMto ca. 6 μMwith an apparentKs(O2) of 3 μM. Enzymatic studies indicated that this respiration was mediated by flavin-linked reduced pyridine nucleotide oxidase(s) and peroxidase(s) and did not involve benzo- or naphtho-quinones. No H2O2accumulation occurred with glucose or mannitol as substrate. Growth yield coefficients of 21.7 and 24.4 with glucose and mannitol respectively as energy sources under aerobic growth conditions indicate that electron flow through these flavin respiratory enzymes was not coupled to any additional energy yielding.

ISSN:0008-4166    

DOI:10.1139/m68-141

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Cholesterol and stigmasterol were isolated fromC.ovatavar.palustris. The compounds were identified by thin-layer chromatography, mass spectroscopy, infrared spectroscopy, derivative formation, and melting point determinations.

ISSN:0008-4166    

DOI:10.1139/m68-142

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The infrared spectra of films of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and synthetic polynucleotides have been studied under varying degrees of relative humidity (R.H.) in the presence and absence of myo-inositol. In addition the effect of 2537 Å light (ultraviolet) on the hydration of DNA has been investigated. As other researchers have shown, when the R.H. is lowered shifts in the P=O and C=O absorption frequencies occur. These shifts seem to be associated with the removal of approximately 12 molecules of water/nucleotide and all are prevented by the presence of 2 molecules of inositol/nucleotide during desiccation. The irradiation of DNA at 75% R.H. with ultraviolet also produces spectral shifts which appear to arise as a result of bound water molecules moving from P=O and C=O groups.The response of bacterial DNA to desiccation appears to depend on the medium in which the cells are grown. The DNA from cells grown in a minimal salts medium is less hydrated at a given R.H. level than the DNA from cells grown in an enriched medium. This loss of water-adsorbing sites is considered to be due to a physiological replacement of water on the DNA of cells grown on minimal salt medium by amino acids or proteins. RNA and polynucleotides are less hydrated than DNA, which is assumed to be due to their lack of an ordered double helical structure. Of the synthetic polynucleotides poly-I was found to most closely resemble the behavior of DNA. The ability of inositol to prevent spectral shifts in DNA caused by desiccation and irradiation tends to substantiate the suggestion that it preserves the biological integrity of cells and viruses during stress by combining with DNA.

ISSN:0008-4166    

DOI:10.1139/m68-143

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Protoplasts ofSaccharomyces cerevisiaeobtained after 1 hours treatment with digestive enzymes of snail are, under the specified conditions, most suitable for metabolic experiments. By estimating the kinetics of the incorporation of leucine-14C, adenine-14C, uracil-14C, respiration, and anaerobic fermentation in protoplasts in a synthetic medium ((NH4)2SO4used as source of nitrogen, glucose as source of carbon, five vitamins, and KCl as osmotic stabilizer) under intense aeration it was found that the incorporation of all the above-mentioned14C-compounds and the rate of respiration rise with the increase in the size of the protoplasts. Thymidine-14C is not incorporated in cells or protoplasts. Comparative studies on the effects of the antibiotics chloramphenicol, oxytetracycline, cyanein, and isothiocyanates characterized by large molecules supplied data showing no differences in the action of these compounds on the cells and protoplasts ofS.cerevisiae.

ISSN:0008-4166    

DOI:10.1139/m68-144

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A purple pigment, named cochliodinol, C32H32N2O4, has been isolated from three isolates ofChaetomium cochliodesand from two isolates ofChaetomium globosum. The pigment is produced intracellularly on a wide range of media in quantities up to 0.45 mg/ml. The rate of production for a given isolate is proportional to its growth but such proportionality is not observed when one isolate is compared to another. A second, fluorescent pigment, C32H28N2O4, is produced by those isolates that produce cochliodinol but in 1/500 of the yield.

ISSN:0008-4166    

DOI:10.1139/m68-145

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Two mouse-adapted influenza virus strains were adapted to growth at 29 °C by a gradual lowering of the temperature of incubation in embryonated eggs. The growth of these two cold variants was completely inhibited at 41 °C. The cold and hot variants showed no significant difference in rise in the infectious titer in the mouse lung but a marked reduction in mortality and pathological response was observed with the cold variants, while good antibody response was stimulated in both cases. The cold variants were better interferon inducers in chick embryo. However, neither cold nor hot variants induced more than detectable amounts of interferon in blood, spleen, or lungs of infected mice. These cold variants possess many characteristics suitable for an effective live virus vaccine.

ISSN:0008-4166    

DOI:10.1139/m68-146

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

An extracellular proteinase from a pseudomonad pathogenic to rainbow trout was purified 33-fold by ammonium sulfate fractionation, DEAE-cellulose column chromatography, and Sephadex G 75 gel filtration. The purified enzyme was active over a wide pH range, from pH 5.0 to 10.0. Heating at 98 °C for 1 h did not completely inactivate the enzyme. Its observed temperature optimum was 45 °C. Michaelis–Menten constants were found to be 0.625% for casein and 0.263% for rainbow trout muscle albumin. Activation energies calculated for these substrates were 8.1 kcal and 11.4 kcal per mole, respectively. The involvement of bivalent cations and free sulfhydryl groups in the enzymatic activity was demonstrated by the inhibition caused by metal-complexing agents andp-chloromercuribenzoate, respectively.

ISSN:0008-4166    

DOI:10.1139/m68-147

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Fractionation of unheated bacillary extract of BCG has yielded a carbohydrate fraction which sensitizes bentonite to react with circulating antibodies toM.tuberculosisin human sera. This fraction does not contain tuberculin-like protein material in appreciable amount, but is rather a mixture of carbohydrates, varying in molecular size and all possessing bentonite-sensitizing activity.

ISSN:0008-4166    

DOI:10.1139/m68-148

出版商:NRC Research Press    

年代:1968

数据来源: NRC