摘要:

A comparison was made of the effects ofcis-tetrachlorodiaminoplatinum (IV) (cis-TCDPt), rans-TCDPt), and hexachloroplatinum (HCP) on growth and cell division ofEscherichia colistrains D21 and D22. At or below 40 μg/mL,cis-TCDPt inhibited cell division but not growth, DNA, or protein synthesis, although areas of increased electron density could be demonstrated in treated cells. In contrast, 40 μg/mL oftrans-TCDPt or HCP inhibited growth.Trans-TCDPt-treated cells developed condensed nucleoids; HCP-treated cells showed no obvious cytological changes to correlate with growth inhibition. Combination ofcis-TCDPt with nalidixic acid, both at one-half the lowest filament-forming concentrations, resulted in formation of filaments, suggesting an additive effect. Combination ofcis-TCDPt followed by ampicillin onE.coliB/r resulted in single bulges near the center of the filaments.Cis-TCDPt could therefore inhibit an initial step in the septation sequence, possibly at the level of the regulation of the hydrolytic enzymes. Whethercis-TCDPt exerts its effect by interreaction with DNA or with a membrane target is still uncertain.

ISSN:0008-4166    

DOI:10.1139/m79-080

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Limiting concentrations of β-glycerophosphate were pulsed into chemostat cultures ofEscherichia coliK-12 at intervals equal to the population doubling time. The resultant culture density fluctuations are interpreted in terms of inorganic phosphate uptake which, in this system, is a function of alkaline phosphatase activity. Information concerningin vivoalkaline phosphatase activity at suboptimal (acidic) pH with very low concentrations of substrate (β-glycerophosphate) is obtained from kinetic analysis of uptake data.

ISSN:0008-4166    

DOI:10.1139/m79-081

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The structure of nitrogen-fixing nodules produced byRhizobiuminfection of the non-legumeParasponia andersoniiwas examined by light and electron (both SEM and TEM) microscopy. Comparisons were made with the nodules previously described onP.rugosa. Like the nodules on different non-legumes formed by other types of endophytes, theRhizobiumnodules onParasponiaresembled modified roots by having a central vascular bundle surrounded by an endophyte-infected zone. The intimate association between theRhizobiumand the host nodule cell was compared with theRhizobiumassociation found in legumes. The rhizobia were not released from the infection thread as happens in the legume. The infection thread, which propagates theRhizobiuminfection to new cells, was transformed within a nodule cell from a darkly stained (light microscopy) or very electron-dense (TEM) structure to a number of thread types. The walls of the threads varied greatly in thickness and often the thread structures were without rigid walls and were only enclosed by a plasma membrane. If the rhizobia are transformed into bacteroids, as in the legumes, it would have to occur when the threads had reached their mature size, when bacterial division had ceased. Nitrogen fixation was considered to occur in all thread types.

ISSN:0008-4166    

DOI:10.1139/m79-082

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Polynucleotide sequences among 24 motile and 11 non-motile aeromonads were studied by analysis of deoxyribonucleic acid – deoxyribonucleic acid (DNA–DNA) duplexes with endonuclease S1. In addition, DNA base composition (mole % guanine and cytosine (G + C) and relative genome sizes were determined for selected strains. Large variations in genome size were found and % GC ranged from 57.1 to 62.9%. On the basis of the strains examined, the GenusAeromonasconsists of two genotypically legitimate groups: a diverse group of motile aeromonads, and the genetically more homogeneous non-motile aeromonads, comprising the speciesAeromonas salmonicida. Internal homology groups could not be demonstrated within the motile aeromonads, and significant divergence in related sequences was indicated. This diverse motile group forms the single speciesAeromonas hydrophila.

ISSN:0008-4166    

DOI:10.1139/m79-083

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

In our laboratory, virus adsorbed to talc–Celite layers is eluted with 100 mL of 10% fetal calf serum (FCS) in normal saline (pH 9.0). A further 10-fold reduction in the volume of the eluate was necessary before its inoculation into cell cultures.A 100-mL volume of an experimentally contaminated sample was placed in a dialysis sac and hydroextracted overnight (4 °C) with polyethylene glycol (PEG) 6000. The viscous material remaining in the sac was resuspended in 10 mL of Earle's balanced salt solution. After membrane filtration (0.2 μm), the concentrate was plaque assayed in BS-C-1 cells. Using this technique, recoveries of five laboratory-adapted enteric viruses (polio 1, echo 6, coxsackie B5, coxsackie A9, and reo 3) and four freshly isolated enteric virus strains (polio 1, echo 1, coxsackie B3, and reo) ranged from 87 to 97%. In comparative tests, PEG hydroextraction was simpler and superior to organic flocculation.

ISSN:0008-4166    

DOI:10.1139/m79-084

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The effects on mortality of supplemental injections of protease and elastase were determined in burned mice infected with non-lethal inocula of a toxin-producing but non-proteolytic- enzyme-producing strain ofPseudomonas aeruginosa. When a variety of solutions containing proteolytic enzyme were injected under these conditions, the mortality increased significantly. This did not occur when organisms other thanP.aeruginosawere used. Injections of the enzyme solutions alone were non-lethal. Injection of a solution of α2-macroglobulin, which was shown to inhibit proteolytic activity, together with a proteolytic enzyme – toxin producing strain ofP.aeruginosacaused a significant delay in mortality when compared with controls. It was concluded that protease, elastase, and toxin production were necessary forP.aeruginosato express full virulence in the burned mouse model.

ISSN:0008-4166    

DOI:10.1139/m79-085

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Cells ofMycobacterium fortuitumkept in 0.85% saline solution containing 0.1% Tween 80 (without glycerol) survive for a long time. In glycerol-enriched medium, they continue to lose their viability at a high rate; after 71 days of exposure the percentage of survival as indicated by colony formation and respiratory and dehydrogenase activities is lower than 1%. Surviving cells starved in medium without glycerol revealed unchanged sensitivity to streptomycin,p-amino-salicylic acid, and isoniazid.

ISSN:0008-4166    

DOI:10.1139/m79-086

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Amphora coffeaeformisvar.perpusillais able to concentrate but not metabolize mannose. The sugar, which can be accumulated against a concentration gradient, is taken up only after a short lag. Preincubation with glucose allows immediate mannose uptake. Substances that reduce the ATP content of the diatom cells also inhibit mannose uptake, as do sugars of similar stereochemical configuration. Mannose appears to act as a non-metabolizable analogue of glucose in these respects.

ISSN:0008-4166    

DOI:10.1139/m79-087

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The synthesis of collagenase inAcinetobactersp. was found to be inducible by denatured collagen and by its high molecular weight fragments. The presence in the inducer of part of the tertiary structure appear to be indispensable. On the other hand, an addition of Casamino acids, meat protein hydrolysate, or a mixture of amino acids with a similar composition to gelatin does not stimulate collagenase synthesis.Enzyme production was severely repressed in the early phase of growth by glucose, arabinose, and ribose, single amino acids, proline, hydroxyproline, alanine, glutamic acid, or casein acid hydrolysate. A mechanism of repression similar to catabolite repression was involved in the phenomenon caused by carbohydrates. However, the fact that cyclic adenosine 3′5′-mono-phosphate did not overcome the repression caused by amino acids or Casamino acids, in contrast to classical catabolite repression, suggests that these two forms of repression may be distinct. [Traduit par le journal]

ISSN:0008-4166    

DOI:10.1139/m79-088

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Treatment ofFusarium sulphureummacroconidial cells with five thiols alters their morphology. Macroconidial cells incubated in dithiothreitol (DTT), dithioerythritol (DTE), or thiourea differentiate into thick-walled, chlamydospore-like cells (thiol-induced spores). These cells appear similar in size and shape to chlamydospores in the light microscope, but differ markedly in cell wall structure when viewed in the electron microscope (EM). Incubation of macroconidia with both DTT and DTE also leads to the formation of large swollen cells (giant cells) which have a parietal cytoplasm and electron-transparent cell walls; most of these giant cells lyse within 3 to 7 days of incubation. Thiourea-induced spores are characterized by the deposition of a thick, electron-dense, extracellular layer and an accumulation of mitochondria. DTT and DTE, at the concentrations used, inhibit macroconidial germination while thiourea, mercaptoethanol, and cysteine do not. With the latter three thiols, the newly formed hyphal cells become elongated with either one or both ends swollen. Mercaptoethanol-treated cells contain an abundance of mitochondria. The DTT-induced spore differs from both macroconidia and chlamydospores with respect to cellular lipid and cell wall composition. While the thiols have different effects on the macroconidia, the fact that they all induce cell expansion suggests that they react at some common sites.

ISSN:0008-4166    

DOI:10.1139/m79-089

出版商:NRC Research Press    

年代:1979

数据来源: NRC