摘要:

Cells of bakers' yeast harvested from a chemically-defined medium were placed in buffer for sporulation experiments and in Wickerham's yeast nitrogen base for growth experiments. The metabolites were included in these two solutions in concentrations up to 1% usually, and growth and sporulation were compared under conditions as nearly equivalent as possible. Optimum sporulation was observed in 0.033–0.1% glucose, 1% pyruvate, 0.033% ethanol, 0.033% acetaldehyde, and 0.33% acetate. Optimum growth in one day occurred in 1% glucose, 1% pyruvate, 0.1–0.33% ethanol, 0.0033% acetaldehyde, and 0.033% acetate. Very few asci were found in 0.33% glucose or in 1% ethanol, but cells transferred to buffer after one day in such solutions sporulated well. The addition of 0.33% glucose or 1% ethanol to 0.3% acetate suppressed sporulation. In 0.1% acetaldehyde no sporulation or growth was evident, with or without the addition of 0.3% acetate. Acetoin, 2,3-butylene glycol, and ethylene glycol had no marked effect on sporulation and growth. Sporulation and growth were inhibited by 7 × 10−4Mfluoroacetate with 0.3% acetate or 0.3% ethanol as the carbon source. Inhibition was much greater when the acetate concentration was decreased to 0.03%. Sporulation in glucose was inhibited by fluoroacetate, while growth in glucose was little affected. With acetate as the carbon source, sporulation was more sensitive than growth to urethane, while the reverse was found with azide, malachite green, cyanide, and dinitrophenol. The two processes seemed about equally sensitive to arsenite,p-nitrophenol, and malonic acid. Most of the asci that formed in glucose solutions were two-spored. In acetate, ethanol, and pyruvate three- and four-spored asci usually predominated, except in the weaker concentrations.

ISSN:0008-4166    

DOI:10.1139/m56-064

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The aphidMyzus persicae(Sulz.) most often became infective with potato virus Y on inserting the styletsonly superficiallyinto infected tobacco plants after a period without food; the further the stylets penetrated into the plant, the less likely the aphid was to be infective. When epidermis was removed from infected plants, aphids acquired virus Y as readily from the exposed mesophyll as from the piece of removed epidermis.M.persicaecan feed by inserting its stylets through a membrane and into tobacco plants. But aphids rarely became infective with virus Y when they inserted their stylets through a membrane and into infected plants; and infective aphids rarely transmitted the virus when they inserted their stylets through a membrane into susceptible plants. Yet infective aphids that penetrated a membrane could afterwards infect a plant not covered with a membrane. Also, aphids did not become infective when they penetrated the deeper tissues of infected plants that had had the virus in the superficial tissues inactivated by ultraviolet radiations. The main conclusion is thatM.persicaerarely becomes infective with virus Y or transmits it after the stylets penetrate beyond the first layer of plant cells.

ISSN:0008-4166    

DOI:10.1139/m56-065

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Transduction has a practical application in a laboratory where the serological analysis ofSalmonellaorganisms is carried out. Non-motile variants of strains may be treated with transducing phage, such that they develop flagella and motility. Such treated strains may then be typed with the appropriate anti-sera. Non-motile, poorly flagellated strains ofS.derby,S.dublin, andS.typhiVi were successfully transduced to motile forms. A phage isolated fromS.thompsonstrain 1/19 (Williams Smith) was found to possess transducing properties. Laboratory methods for the transducing procedure are outlined.

ISSN:0008-4166    

DOI:10.1139/m56-066

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

An investigation with 115 strains ofS.typhi-muriumisolated from a variety of sources revealed that 12.1% (or 14 strains) carried transducing phage. The highest incidence was found among strains obtained from human sources. Suggestive evidence of antigenic changes taking place in nature is given and the possible role of transduction in the evolution of the genusSalmonellais discussed.

ISSN:0008-4166    

DOI:10.1139/m56-067

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Uredospores of wheat stem rust utilized a number of externally-supplied, labelled carbohydrates, amino acids, and volatile fatty acids. The carbon of these substrates appeared in the spore materials and in the carbon dioxide. This metabolic activity, though very weak, is definite.D-Mannose,D-mannitol,D-glucose, sucrose, andD-fructose were utilized better than the other carbohydrates. Glutamic acid gave the highest yield of carbon dioxide while the basic amino acids,L-arginine andL-lysine, were more efficiently incorporated into the spore material.

ISSN:0008-4166    

DOI:10.1139/m56-068

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The present study was undertaken to determine the cause of the wide variation in the response of mice following intranasal challenge with virulentH.pertussis. Mice, both normal and immunized, were inoculated intranasally with killedH.pertussisorganisms labelled with iodine-131. The course of the tagged antigens, in the lungs and other organs of these animals, was followed by radioisotope counting. The lung uptake varied from 31.6% to 77.5% of the challenge dose in immunized animals and from 25.0% to 83.7% in non-immunized animals. It was considered that this variation was large enough to contribute substantially to the wide discrepancies found in animal assays. To date the cultures employed for intranasal challenge have all been of low virulence when administered by this route. A considerably more virulent strain of challenge organism than those in use now would be necessary to overcome the variations in the assay caused by uneven lung uptake of challenge culture. It was also found that the lungs of immunized mice were cleared more rapidly than the lungs of non-immunized mice in the 24-hr. period following the intranasal inoculation.

ISSN:0008-4166    

DOI:10.1139/m56-069

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Concentrations of selenite and tellurite that are somewhat inhibitory to the growth of yeastlike fungi are shown to cause a variety of filament-producing organisms to grow exclusively in a yeast-phase condition. This effect is shown not to be a selective inhibition of the filamentous type of growth, but a promotion of cellular division. With subbacteriostatic concentrations of many antimicrobial agents it is well known that a filamentous type of microbial growth can be obtained owing to selective inhibition of cellular division, but this is believed to be the first instance in which antimicrobial agents have been shown to enhance division of normally filamentous cells. Analogies are drawn between the properties of sulphur-containing compounds and those with selenium or tellurium. Information is presented on the occurrence of a sulphur-rich protein in the cell wall of yeasts and on the occurrence of organically bound selenium in the cell wall of organisms grown on selenite.

ISSN:0008-4166    

DOI:10.1139/m56-070

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

P32incorporated in ribo- and desoxyribo-nucleic acids during multiplication ofEscherichia coliwas retained there as nucleotide phosphorus during subsequent generations. There was little or no unequal exchange of P32between the nucleotides of either nucleic acid during bacterial multiplication. The kinetics of assimilation of inorganic P32from medium of constant specific activity into the nucleotides ofE.colinucleic acids indicated that phosphorus was incorporated faster into RNA than DNA.E.coliwas propagated for two minutes in the presence of inorganic P32and the rate at which this "two minute" P32was incorporated into RNA and DNA phosphorus was measured. About 50 to 60 min. was required for both RNA and DNA phosphorus precursor pools to empty. P32was incorporated into RNA at a faster rate than into DNA. The final ratio RNAP32/DNAP32was 50% higher than would be expected from the ratio RNAP/DNAP inE.coli. An equal exchange of phosphorus between RNA and DNA does not occur during bacterial multiplication.

ISSN:0008-4166    

DOI:10.1139/m56-071

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The isocitric, succinic, malic, and lactic dehydrogenases and cytochrome oxidase fromPseudomonas salinaria, an extreme halophile, are most active in high concentrations of sodium or potassium chloride. The lactic dehydrogenase and cytochrome oxidase ofMicrococcus halodenitrificansare also more active at high concentrations of salt, but the isocitric, succinic, malic, α-ketoglutaric, and glutamic dehydrogenases of this moderate halophile are most active at much lower concentrations. It is concluded that the extreme halophiles have a high intracellular salt content. It is suggested thatM.halodenitrificansmaintains an intracellular salt concentration of about 0.5Munder optimal conditions for growth and that cytochrome oxidase is important in maintaining this level against a concentration gradient.

ISSN:0008-4166    

DOI:10.1139/m56-072

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The ability of lactic streptococci to utilize unhydrolyzed sodium caseinate as the nitrogen source in an otherwise chemically defined medium seems to be a strain rather than a species characteristic. This characteristic therefore appears to have little value as an aid in classification although it might have some importance in selection of starter cultures for cheese manufacture. None of the enterococci examined grew with unhydrolyzed sodium caseinate as the sole nitrogen source. However,Streptococcus liquefaciensandStreptococcus zymogenesappeared to utilize sodium caseinate when small amounts of casein hydrolyzate were added to the medium.

ISSN:0008-4166    

DOI:10.1139/m56-073

出版商:NRC Research Press    

年代:1956

数据来源: NRC