摘要:

A strain ofPenicillium cyaneo-fulvumisolated in this laboratory elaborates an antiviral substance in Czapek-Dox broth which inhibits the multiplication of influenza A and B and Newcastle disease viruses in modified Maitland tissue cultures. However, the multiplication of these viruses as well as mumps virus was not inhibited when tested in embryonated hens' eggs. No antiphage activity was demonstrated against a ribonucleic acid containing phage (f2) and a single-stranded deoxyribonucleic acid containing phage. The antiviral substance in a semipurified form, derived by precipitation of impurities from the culture filtrates with acetone, contains sugars, amino acids, and nucleic acid components, and shows a peak at about 270 mμ in its ultraviolet absorption spectrum, with a 280 mμ/260 mμ ratio of 0.97. It is stable to heat, lyophilization, repeated freezing and thawing and it is not dialyzable. Results of enzyme inactivation of the active principle were not conclusive.

ISSN:0008-4166    

DOI:10.1139/m68-033

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

An antiviral substance elaborated in Czapek-Dox broth by a strain ofPenicillium cyaneo-fulvumisolated in this laboratory, and active against influenza A virus (PR8), influenza B virus (Lee), and Newcastle disease virus (B1) in modified Maitland tissue cultures has been shown to act at an intracellular site in the viral replicative cycle. The substance neither blocks virus adsorption nor impedes the release of newly formed virus particles. It is not viricidal, does not interfere with the action of ths viral neuraminidase on red blood cells, and does not possess any haemagglutination or haemagglutination–inhibition activity. A comparison with other reported antiviral agents shows that the antiviral substance is different from those previously studied.

ISSN:0008-4166    

DOI:10.1139/m68-034

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The ultrastructure ofP.terrestrishyphal cells was investigated to compare frozen-etched replicas with chemically fixed thin sections. The fungus used in this study uses glycerol as a sole carbon source and survives the freezing procedures necessary for freeze-etching; thus frozen-etched replicas reflect the living state.Frozen-etched membrane systems have particles of various sizes and concentrations and have a smooth appearance as contrasted to chemically fixed membrane systems, which have particles difficult to distinguish and somewhat irregular membrane systems. Frozen-etched cell walls are seen to contain particles, and microfibrillar orientation is evident in older cell walls, whereas substructure is not evident in chemically fixed cell walls, although secretion products of the fungus accumulate on cell surfaces.Chemically fixed ground cytoplasm has ribosomes and areas of high- and low-electron scattering which are not seen with freeze-etching. Cells fixed in glutaraldehyde–acrolein–OsO4more nearly resemble frozen-etched cells than cells fixed in potassium permanganate.

ISSN:0008-4166    

DOI:10.1139/m68-035

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A method for the purification of rhapidosomes from flexibacteria is described. The substructure of the purified rhapidosomes (as seen by electron microscopy) is shown and their resemblance to similar particles which are found in other bacteria is discussed.

ISSN:0008-4166    

DOI:10.1139/m68-036

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Proteinase in culture fluids of an obligately psychrophilic bacterium was precipitated by ammonium sulfate and fractionated by gel filtration and DEAE-cellulose chromatography. Three purified fractions (I-1, I-2, and III-1) with proteinase activity were obtained. On the basis of reactions and characteristics (i.e. effect of pH, heat, and metal ions on activity and stability, hydrolysis of synthetic peptides and of natural proteins) fractions I-1 and III-1 appeared to be very similar whereas fraction I-2 was different. When proteinase preparations were examined by electrophoresis, fractions I-1 and III-1 gave similar patterns; fraction I-2 gave a different one. From the results it is suggested that the organism produces two proteinases and that possibly fraction I-1 represents an aggregation of molecules of III-1 and that fraction I-2 is a different proteinase.

ISSN:0008-4166    

DOI:10.1139/m68-037

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The appearance of proteolytic enzymes in culture fluids during growth of an obligately psychrophilic red-pigmented bacterium and of a white variant was followed. Enzymes were precipitated with ammonium sulfate and fractionated on Sephadex G-100. Both organisms produced a slow-moving component (III) at the start of proteinase production and a fast-moving component as the culture aged. The fast-moving component of the red but not of the white organism was separated into two fractions (I-1 and I-2) on DEAE-cellulose. On filtration through Sephadex, fraction I-1 gave rise to fraction III; fraction I-2 gave rise to enzymatically active I-2 and inactive red pigment. It is suggested that both organisms produce fraction III initially and that this aggregates to form fraction I-1 and that the red organism produces fraction I-2, which is a separate protein.

ISSN:0008-4166    

DOI:10.1139/m68-038

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Fourth and fifth instar larvae ofGalleria mellonellawere inoculated by injection or "per os" with two strains ofSalmonella typhimurium. After injection of 2 × 104viable units, the average mortality was 68%, with strain 7 Suc LL, and 26% with strain LT2; by per os inoculation, mortality was 58% and 18% respectively. During infection, the number of bacteria increased and the total hemocyte count decreased by 64% with a consequent impairment of phagocytosis. Infection under similar conditions with a saprophytic Enterobacteriaceae species,Escherichia colihad no effect. Since the wax-moth infests beehives the possibility ofSalmonellainfection may be of epidemiological significance.

ISSN:0008-4166    

DOI:10.1139/m68-039

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A method is described of plotting deoxyribonucleic acid (DNA) thermal melting data which allows information other than average content of guanine plus cytosine to be determined. Absorbancy (A) values, corrected for thermal expansion, are plotted on normal probability graph paper and the best straight line drawn. The 50 percentile point on the graph establishes theTmvalue which allows calculation of the mean base composition. In addition the 2σ (twice the standard deviation) value is easily determined from the probability plot, thus providing information about the degree of variation from the mean in DNA base composition. Comparison of the probability plot and usual graphic methods of determiningTmvalues provided similar DNA composition data on 15 different strains ofStreptococcus lactis,Streptococcus cremoris, andStreptococcus diacetilactis. When manyAvalues obtained from streptococcal DNA samples showing skewed thermal melting curves (S.lactis bandS.diacetilactisDRC-2) were plotted on normal probability paper, two intersecting straight lines were apparent on the graph. This suggested that there were two types of DNA in these organisms. Each had its own unimodal compositional distribution and its presence was confirmed by density gradient separation. The use of normal probability plots as a rapid method of determining average base composition of DNA samples is suggested. In addition, heterogeneity in base composition may be shown by this method of plotting the data.

ISSN:0008-4166    

DOI:10.1139/m68-040

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Ten strains ofRhizobium melilotiwere compared by immunochemistry. A polysaccharide-precipitin band is identified by a specific staining method. The polysaccharide-precipitin band is common to the 10 strains ofR.meliloti.

ISSN:0008-4166    

DOI:10.1139/m68-041

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A psychrophilic marine bacterium was stable in cold seawater or in a solution containing 0.1 MMg++and 0.5 MNaCl. In water and in a number of monovalent salts, including up to 3.0 MNaCl, turbidity of suspensions fell and some intracellular material was released into the external medium. The cells first became swollen and pale under phase contrast optics and then disintegrated into amorphous aggregates. Divalent salts alone, some in very low concentrations, could maintain cell structure. Effectiveness was in the order Cu++ > Zn++ > Ni++ > Ca++ > Mn++ > Mg++. The polyamine, spermine, was ineffective. In the presence of 0.1 MMg++, NaCl and, less effectively, LiCl and RbCl could maintain structure, but KCl, NH4Cl, CsCl, glucose, and sucrose could not. Sodium phosphate, pH 7.0, caused lysis but other sodium salts maintained structure in the presence of Mg++. For growth, Mg++, NaCl, and traces of other ions were required.Phosphatidases attacking cells at 25 °C and higher required salts for maximum activity. The turbidity of water-lysed cells or of envelopes prepared from mechanically broken cells fell at 25 °C and higher; this fall was also dependent on the presence of salts. If cells were lysed in distilled water, or broken mechanically in the presence of salts, more than half their lipid phosphorus and hexosamine was released from material sedimenting after 30 min at 15 000 × gbut these materials were not degraded into other substances. The released material seemed bound to smaller particles, since most of it sedimented after 1 hour at 100 000 × g. The lipid composition of smaller and larger particles, and of whole cells, was the same.

ISSN:0008-4166    

DOI:10.1139/m68-042

出版商:NRC Research Press    

年代:1968

数据来源: NRC