摘要:

The Hoff-Jorgensen method for the quantitative determination of deoxyribonucleic acid was successfully simplified by using commercial acid- and enzymehydrolyzates of casein, together with supplements of uracil and pyridoxine, in place of laboratory-prepared hydrolyzates in the assay medium.

ISSN:0008-4166    

DOI:10.1139/m63-035

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

DL-Tryptophan-β-C14, but notL-phenylalanine-U-C14norL-tyrosine-U-C14, is incorporated into the ergoline moiety of the ergot alkaloids. The high specific activities of the bases isolated from cultures supplemented with a mixture ofDL-tryptophan-β-C14and carrierL-tryptophan indicate some contribution from theD-isomer.L-Phenylalanine-U-C14serves as a precursor of the lysergic acid and isolysergic acid derivatives which contain this amino acid in their peptide moieties.L-Tyrosine-U-C14is not a precursor. The distribution of activity in the cultures at the end of the growth phase suggests that, in the strain ofClaviceps purpureaused in these investigations, none of these aromatic amino acids is extensively degraded. All are incorporated directly into cell protein. A portion of the phenylalanine is hydroxylated to tyrosine and this pathway appears to be of major importance in tyrosine biosynthesis. All three of the amino acids were incorporated extensively into a red-brown pigment which is probably a polymer of the quinone – amino acid type.Under the conditions used in these experiments small but significant amounts of mevalonic acid-2-C14and formic acid-C14were used in alkaloid biosynthesis.

ISSN:0008-4166    

DOI:10.1139/m63-036

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A number of Gram-negative cold-tolerant bacteria capable of growth on agar at 0 °C but not at 25 °C were isolated from Arctic littoral and marine sediment samples. Eight of these organisms able to hydrolyze gelatin were chosen for study. Taxonomically these organisms consisted of an unidentified but closely related group of seven cultures and a singlePseudomonasstrain. Culture supernatants of these Arctic organisms contained proteinases that hydrolyzed gelatin, casein, and β-lactoglobulin, but not bovine plasma albumin. When casein was the substrate, the proteinases were most active at pH 7.0 to 8.0 between 30° and 40 °C and were inhibited by ethylenediaminetetraacetic acid. The proteinases were relatively heat-labile; the activity of the most heat-labile was reduced by 90% in 20–30 minutes at 40 °C and that of the most heat-stable by 90% in 45 minutes at 50 °C. Proteinases of the unnamed group of Arctic organisms were characterized by a lowtemperature characteristicand possession of high enzymic activity at low temperatures. Presumably such organisms can convert protein to simple nitrogenous compounds in the Arctic environment.

ISSN:0008-4166    

DOI:10.1139/m63-037

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Cultures of a number of tissue cell lines were observed to be infected with an organism of the kind usually referred to as PPLO. That the organism was in reality theL-form of a diphtheroid was demonstrated by the repeated recovery of the bacillary form fromL-type colonies. The cultural procedure employed to recover the bacillary phase is described, and, as well, some of the characteristics of theL-type organisms and the diphtheroid. Attempts to eliminate theL-type organisms from tissue cultures by means of certain antibiotics and heat treatment were unsuccessful.

ISSN:0008-4166    

DOI:10.1139/m63-038

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A definite variation in sensitivity to gamma radiation was found among 18Salmonellaspecies commonly occurring in frozen whole egg. The dose levels required for a 107-fold reduction of these species ranged from 0.36 Mrad to 0.54 Mrad. Variation in sensitivity to radiation was also detected with three cultures ofS.pullorumwhich appeared similar except in origin. Variation in sensitivity within all species ofSalmonellastudied apparently indicates that no one species can be considered most resistant. These studies reveal that a level of 0.54 Mrad of gamma radiation would reduce the salmonellae to a safe level in frozen egg. As a result, the product treated by the above method could be commercially acceptable and present no public health problem with respect to salmonellae.

ISSN:0008-4166    

DOI:10.1139/m63-039

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Anaerobiosis and other physical means were found to induce streptomycin-sensitive (SMs)Vibrio commato lethal biosynthesis of an antibacterial principle. The optimal conditions for its production are given and the similarity to induction of bacteriophage in lysogenic bacteria discussed. Means for detection of the antibacterial principle are described. Some of the chemical and physical properties are reported. The antibacterial substance synthesized byV.commais named "vibriocin".

ISSN:0008-4166    

DOI:10.1139/m63-040

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The relationship between vibriocin production by streptomycin-sensitive (SMs)Vibrio commaand a specific redox potential is described. Streptomycin-resistant (SMr) mutants are shown to be predominantly sensitive to vibriocin and thus serve as indicator strains. Vibriocin sensitivity can be demonstrated under aerobic but not anaerobic test conditions. A discussion is given, implicating bacteriocins as a factor contributing to the "Welsch phenomenon" wherein the growth of a mixed population of SMs and SMr bacteria in broth results in a steady decrease of the SMr mutants to the level normally present in a sensitive culture.

ISSN:0008-4166    

DOI:10.1139/m63-041

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Glutamic dehydrogenase was extracted from germinated uredospores ofPuccinia helianthiand partially purified. The enzyme was specific for nicotinamide-adenine dinucleotide was inhibited by several metal-chelating agents and was shown to possess sulphydryl groups essential for activity.

ISSN:0008-4166    

DOI:10.1139/m63-042

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Pythiumisolates exhibited slight or no cellulose-decomposing activity in terms of strength loss produced in "scoured" (heated in 1% NaOH) cotton fabric incubated with the fungus. When, however, scoured fabric was swollen in 18% sodium hydroxide, neutralized, and inoculated with the fungus before the fabric dried, major strength losses occurred. Casamino acids, yeast extract, and asparagin added singly to the test medium caused relatively little or no increase in strength loss. Cotton fiber in the natural swollen state found in the unopened cotton boll underwent major strength loss during incubation with severalPythiumisolates.It is concluded that compactness of the cellulose structure in an unswollen cotton fiber offers an impediment to degradation byPythium.

ISSN:0008-4166    

DOI:10.1139/m63-043

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Poliovirus suspensions of different types and strains, as well as vacuolating virus (SV-40) and human herpes virus, were adjusted to various points between pH 8.5 and pH 1.5. The comparative inactivation of these viruses was established for different conditions of temperature and time of treatment. There appeared to be a large enough difference in the resistance of the poliovirus group on the one hand and that of herpes and vacuolating virus on the other to permit a selective inactivation of these last-mentioned viruses in contaminated suspensions of poliovirus. A few assays done with foamy virus showed that this selective inactivation could be applied also to poliovirus suspensions contaminated with this agent.This simple technique could be of help in the preparation of poliomyelitis vaccine, live or inactivated.

ISSN:0008-4166    

DOI:10.1139/m63-044

出版商:NRC Research Press    

年代:1963

数据来源: NRC