摘要:

Temperate bacteriophages of diverse morphology were demonstrated by electron microscopy in toxigenic cultures ofClostridium botulinum. The 41 strains examined included 23 type E and multiple representatives of all other types. Cultures induced with mitomycin-C generally gave better yields, but phages were also demonstrable in untreated cultures.A provisional grouping of toxigenic types into four categories is suggested, based mainly upon associated phage patterns. Group 1 comprises types A, B, and F (all proteolytic), many of whose cultures showed an icosahedral contractile phage; others contained a "bullrushy" phage with elongated head and long flexible tail; some strains yielded both. Group 2, types B and F (non-proteolytic), were associated with icosahedral contractile phages; the latter also had an octahedral flexible phage. Group 3, types C and D, yielded conspicuously large phages with octahedral heads and very long sheathed tails. One type C strain produced a long-tailed icosahedral phage. Type E phages constituted group 4. These were icosahedral with tails generally contracted but sometimes flexible, often accompanied by superfluous sheathed tail-like structures resembling certain bacteriocins. Although non-toxigenic "OS" mutants of types A, B, E, and F were phageless, two non-toxic type E strains yielded phages. The possible role of lysogeny in the toxigenicity of certain types of this species is likely to prove difficult to elucidate.

ISSN:0008-4166    

DOI:10.1139/m72-011

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The phages belong to the conventional morphological groups A1, B1, and C1. They have octahedral heads and either contractile, long non-contractile, or short tails. Our findings confirm the validity of the Felix and Callow typing scheme. Preparations of phage Beccles have been shown to contain abnormal particles such as tail tubes of various lengths, either with or without heads and tail sheaths. Some may even possess two tail sheaths. Isolated sheaths aggregate spontaneously into chains. Preparations of phage Jersey contain numerous phage tails of abnormal lengths and a few complete phages with elongated tails.

ISSN:0008-4166    

DOI:10.1139/m72-012

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Heat-inactivated antiserum in the absence of complement inhibits colony formation of mouse leukemia L5178YR cells in soft agar. Cells derived from resistant clones in these plates showed the same sensitivity to antiserum as the parent population. Agglutination of the cells was prevented by placing the antiserum dilutions over the cell-containing agar layer. This clearly indicates that cell agglutination by antiserum is not necessarily the essential cause of growth inhibition.

ISSN:0008-4166    

DOI:10.1139/m72-013

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Resting bodies ofBdellovibriosp. strain W were produced following the infection ofRhodospirillum rubrumin liquid culture. Thin sections showed that young resting bodies possessed a narrow layer of amorphous material at their periphery, and storage granules in the region of the nucleoplasm. In mature resting bodies, the amorphous material (now called the outer layer) had thickened considerably to 30–40 nm, and the cell wall had differentiated into a folded, tripartite inner layer. Freeze-etched preparations of mature resting bodies showed a roughly particulate plasma membrane, a more finely particulate inner layer, and an outer layer having little structure.BdellovibrioW did not produce resting bodies in a second host,Escherichia coliB. AlsoB.bacteriovorusstrain 109 failed to form resting bodies inE.coliB, its usual host. It also failed to grow in cultures ofR.rubrum. These restricted experiments suggest that the development of resting bodies may be specific for theBdellovibrioW –R.rubrumparasite–host system.

ISSN:0008-4166    

DOI:10.1139/m72-014

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The replicative events of a virulent phage (A25) infection of a group AStreptococcus(T253) were studied using the electron microscope. The first intracellular evidence of phage replication in a cell occurred 30 min after infection with arrest of cell division and increase in the nucleic acid pool. Phage heads were evident in the nucleic acid pool of the cells 45 min after infection. Release of phages occurred by splitting of the cell wall along discrete lines. This appeared to be at sites of active wall synthesis, i.e., near the region of septum formation. Many phage components were released but relatively few complete phages indicating a relatively inefficient replicative system.

ISSN:0008-4166    

DOI:10.1139/m72-015

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Percentage lesion of the deoxyribonucleic acid (DNA) hybrids of 19 strains of proteolyticClostridium botulinumandClostridium sporogeneswas determined by the thermal stability method. The maximum noncomplementary lesion was 6–9%, but in most instances the lesions were much less than 6 or 9%. The results indicated that the DNA hybrids ofC.botulinumandC.sporogenestested were homologous, and that some of these toxic and nontoxic strains are closely related.

ISSN:0008-4166    

DOI:10.1139/m72-016

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The effects of subinhibitory doses of chloramphenicol and oxytetracycline on chromogen formation by normal and antibiotic-resistantPseudomonas aeruginosastrains were studied. Partial or total inhibitions of the phenazine compounds were observed while the oxyphenoxazone synthesis appeared increased. In addition, several molecular modifications, presumably as a physiological response against the damaging drugs, were detected.

ISSN:0008-4166    

DOI:10.1139/m72-017

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The replicative cycle of the Kilham rat virus (RV-13) in rat embryo (RE), hamster embryo (HE), and L-929 cell cultures was studied under conditions of high viral input multiplicity. The synthesis of RV antigen in infected cells was followed by the indirect fluorescent antibody (FA) technique and correlated with the appearance of extracellular hemagglutinin. The synthesis of specific antigen in RE and HE cell cultures appeared to follow a similar pattern. Cytoplasmic fluorescence was observed early in the replicative cycle of RV in both host systems. Nuclear fluorescence was detected 6–8 h later after a decline in the number of cells exhibiting cytoplasmic fluorescence. Nuclear fluorescence appeared more extensive and more intense in RE cells. In addition, a significantly higher hemagglutinin titer was obtained from the infection of RE cells. The replicative cycle of RV in L-929 cells appeared aborted. Although the synthesis of RV structural antigen was detected in the cytoplasm of these cells, subsequent nuclear fluorescence was totally absent and extracellular hemagglutinin was not detected.

ISSN:0008-4166    

DOI:10.1139/m72-018

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The nutritional requirements for culture ofPasteurella ureaein a chemically defined medium were determined. The medium in which the species grew best contained 16 amino acids:L-arginine,L-glutamic acid,L-alanine, andL-threonine were nutritionally essential;L-aspartic acid,L-leucine, andL-tryptophane were markedly stimulatory. The species also required uracil plus two purines, and two vitamins, nicotinamide and pantothenate.

ISSN:0008-4166    

DOI:10.1139/m72-019

出版商:NRC Research Press    

年代:1972

数据来源: NRC