摘要:

Production of ergot alkaloids by cultures ofClaviceps purpureawas regulated by altering single experimental variables and the pattern of changes in mycelial constituents examined. Cultures which produced alkaloid ceased to accumulate polyols, carbohydrate, and lipid in the mycelium just prior to the onset of alkaloid synthesis whereas the concentration of water-extractable nitrogen and ribonucleic acid remained high or increased. Cultures which failed to produce alkaloid continued to accumulate carbohydrate, polyols, and lipid, but not nitrogenous constituents in the mycelium throughout the late growth phase. The differences between producing and non-producing cultures were consistent irrespective of method used to control the formation of alkaloid. The results suggest that production occurs only under conditions where the accumulation of certain non-nitrogenous cell components has ceased. No consistent correlation was observed between alkaloid production and changes in condensed inorganic phosphate or orthophosphate in the mycelium.

ISSN:0008-4166    

DOI:10.1139/m63-001

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Aspergillus flavusproduces an adaptive enzyme (or enzymes) that cleaves the heterocyclic ring of 1 mole of quercetin using 1 mole of oxygen to yield 1 mole of carbon monoxide and 1 mole of the depside, 2-(3′,4′-dihydroxybenzoyloxy)-4,6-dihydroxybenzoic acid. The enzyme acts on chromones that possess a substituent such as a methyl or a phenyl group on carbon 2, a free hydroxyl on carbon 3, and a double bond between carbons 2 and 3. These requirements must also be present in a substrate if production of the enzyme is to be induced. The enzyme was purified 40-fold by treatment with Sephadex followed by adsorption on and elution from diethylaminoethyl cellulose and calcium phosphate gel, then by heating, and finally by precipitation with ammonium sulphate. The enzyme is stabilized towards denaturation by heat, by its substrate, or by low concentrations of ammonium sulphate. It is stable for long periods when lyophilized or stored in solutions at −20 °C. The optimum pH for activity lies between pH 5.0 and 7.0 and maximum stability occurs at pH 6.0.

ISSN:0008-4166    

DOI:10.1139/m63-002

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A group of 109 healthy adult blood donors was examined to determine the incidence of anticapsular antibodies capable of eliciting a specific capsular reaction when tested against an encapsulated strain ofStaphylococcus aureus. At the same time the carrier rate for naturally occurring encapsulatedS.aureusvariants was determined. Of the healthy blood donors 80.7% possessed anticapsular antibodies in sufficient titer to elicit a specific capsular reaction. Almost half the carriers of staphylococci carried naturally occurring encapsulated strains ofS.aureus. In a group of subjects below the age of 13 years, a lower incidence of anticapsular antibodies was found.

ISSN:0008-4166    

DOI:10.1139/m63-003

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The green alga haematococcus was tested for nitrate uptake in the presence of ammonium. Preference for the nitrate ion was controlled by initial pH of the medium and by age of the culture inoculum.Critical age and initiai pH forH.pluvialisFlotow, Cambridge U. strain 34/1aand forH.lacustris(Girod.) Rostaf., Indiana U. strain 294, were different. When inocula consisted of cells in log phase of growth, cultures ofH.pluvialispreferred ammonium in medium that was pH 7.0. Only a small percentage ofH.lacustriscultures preferred ammonium and only when the medium was as acid as pH 4.8. Increased age of the inoculum decreased sensitivity to pH of the culture medium.Nitrate uptake inH.lacustriswas less sensitive to external pH and seemed to be more exclusive than inH.pluvialis.

ISSN:0008-4166    

DOI:10.1139/m63-004

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A comparative study has been made of the chemical composition of cell walls from two strains ofEscherichia coli—one rough strain which was very sensitive to killing and lysis by normal human serum, and one smooth strain which was relatively insensitive to killing and was not lysed at all. The major components in the cell walls of both strains were protein and (or) polypeptide (70–80%) and lipid (14%), no significant differences in either component being detected between the two strains. A marked difference was, however, detected in the lipopolysaccharide fraction which was present to the extent of only 1% in the walls of the rough, serum-sensitive strain and 9% in the smooth, serum-resistant strain. Moreover, the two lipopolysaccharides were qualitatively different in sugar composition, that from the resistant strain yielding glucose, galactose, rhamnose, and two minor sugar components, while that from the sensitive strain yielded glucose only. These findings are discussed in relation to the three-layer theory for the structure of the coli cell wall and in relation to the serum factors (antibody, properdin, complement, and lysozyme) which may participate in the destruction of bacteria by serum.

ISSN:0008-4166    

DOI:10.1139/m63-005

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

At low pH values much of the surface structure ofHalobacterium cutirubrumis maintained, even in the absence of the high salt concentration normally needed to keep this organism from dissolving. If the pH is then raised in solutions of low ionic strength, the cells dissolve. Sphere formation takes place below pH 3 in the absence of salt, and at pH values of about 4 and about 11 in the presence of 4.5 MNaCl. In the latter, there is at first little leakage of intracellular constituents, and the surface of the spheres retains the woven pattern characteristic of the surface of the untreated cell. Below pH 3, this pattern disappears, and the cells become almost completely or completely permeable. In 1% acetic acid, NaCl and KCl have the same effect on cell morphology, in contrast to their differential effects on intact cells. The morphological changes observed appear primarily due to changes in the cell membrane, and are not caused by osmotic pressure.

ISSN:0008-4166    

DOI:10.1139/m63-006

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Since 1850, aphids have been regarded as harboring, in mycetomes, supposedly beneficial microorganisms which have, however, been the subject of some controversy. In the present study of the aphidsAphis jabaeandMacrosiphum pisi, mycetomes were identified in histological sections; but it proved impossible to isolate or culture any mycetomal microorganisms. Moreover, in a series of experiments in which great attention was paid to refined aseptic techniques no microorganisms could be isolated from the general body cavities or alimentary tracts of the aphids, though simultaneous attempts to isolate microorganisms from weevils were successful.

ISSN:0008-4166    

DOI:10.1139/m63-007

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

It was confirmed that mice bearing many transplantable tumors are infected with a virus-like agent which causes a 5- to 10-fold elevation in the plasma lactic dehydrogenase activity of infected mice without tumors. The agent is non-identical with the polyoma virus and without effect on adult rats and hamsters. Maximum titers of 109to 1010ID50per ml of plasma were observed within 36 hours after infection. Subsequently the titer decreased to 105to 107ID50per ml and remained constant thereafter. The plasma lactic dehydrogenase reached maximum activity about 96 hours after infection and remained elevated indefinitely. The virus was present in feces and in a variety of tissues and organs in relatively high concentrations. Liver and spleen yielded the highest titers.Five electrophoretically distinct forms (isozymes) of lactic dehydrogenase were separated from mouse tissues. Infection of mice resulted in an increase of the slowest migrating isozyme in the plasma. Liver, spleen, and erythrocytes were each found to contain only this isozyme while other tissues and organs contained mixtures of lactic dehydrogenase isozymes. The plasma of tumor-bearing mice contained more of the slowest migrating isozyme than infected mice without tumors.

ISSN:0008-4166    

DOI:10.1139/m63-008

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The inactivation of Pigeon Pox and Rous sarcoma viruses (R.S.V.) at various relative humidities (R.H.), with and withouti-inositol, was studied. Pigeon Pox virus was found to be stable in aerosols and was little affected by changes in R.H. R.S.V., however, was extremely sensitive to R.H. and survived best at R.H. levels above 70%. Inositol at a concentration of 6.0% was able to prevent the inactivation of R.S.V. Holding the viruses in aerosols at 80% R.H. or protected with inositol at 30% R.H. appeared to increase their virulence towards the assay eggs and experimental animals.

ISSN:0008-4166    

DOI:10.1139/m63-009

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Coagulase-positive staphylococci produce discrete compact colonies when grown in a semisolid medium containing rabbit serum or plasma. In contrast, the same organisms produce elongated diffuse colonies when grown in the basal medium. Coagulase-negative staphylococci, on the other hand, produce diffuse colonies in both media, but were found to produce compact colonies when the basal medium was enriched with homologous antibody-containing serum.Sixty-three strains were studied, 56 of which were coagulase positive. The strains were from different sources—human, canine, bovine, and equine. A number of strains did not conform to the normal pattern. Attempts were made to establish the relationship between agglutinin titers and colony-compacting antibodies.

ISSN:0008-4166    

DOI:10.1139/m63-010

出版商:NRC Research Press    

年代:1963

数据来源: NRC