摘要:

Cell-associated enterotoxin B was detected in lysates of cells ofStaphylococcus aureusS-6 and 4916 disrupted by sonication or lysostaphin treatment. As much as 67% of this total cell-associated toxin was surface-bound, located outside the cytoplasmic membrane, and was released during protoplasting of this organism by lysostaphin treatment in hypertonic medium. The remainder of the cell-associated toxin was termed cytoplasmic and was released during osmotic lysis of the protoplasts. Levels of cell-associated toxin as a function of the age of the cells showed a rapid increase in both surface-bound, cytoplasmic, and total cell-associated toxin levels during the period of active toxin synthesis (late exponential phase of growth). These cell-associated toxin levels then reached a peak as the culture entered stationary phase, at a time corresponding to a decrease in the rate of toxin synthesis, and decreased slowly thereafter.

ISSN:0008-4166    

DOI:10.1139/m76-180

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Bovine polymorphonuclear leukocytes (PMN) mediated antibody-dependent cell cytotoxicity (ADCC) against erythrocyte and herpes virus-infected target cells. The extent of cytotoxicity was not affected by drugs that inhibited DNA, RNA, or protein synthesis. The effect did not occur in the absence of divalent cations, was suppressed by pretreatment of PMN with silica and cytochalasin B, and was subject to the bidirectional control by cyclic nucleotides: drugs decreasing cyclic AMP or elevating cyclic GMP levels enhanced ADCC. The ADCC phenomena was also enhanced by supernates containing immune interferon activity from antigen-stimulated-immune lymphocyte-macrophage cultures. The possibility that immune interferon(s) might be causing the elevation of ADCC and the relevance of this observation in terms of the part interferon might play in modulating recovery from herpes virus infections was discussed.

ISSN:0008-4166    

DOI:10.1139/m76-181

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

When transplanted repeatedly at 37 °C, the strainClostridium botulinumtype C exhibits the tendency to lose its toxigenic activity. Two types of colonies are identified on agar medium. The morphology of these colonies is closely related to their ability to synthesize the toxin.

ISSN:0008-4166    

DOI:10.1139/m76-182

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Chelating agents disrupted the superficial layers onSpirillum putridiconchyliumand adsorption of cationized ferritin indicated that both upper and lower surfaces of superficial layer fragments, as well as the outer membrane surface, possessed areas which were negatively charged. Growth of the bacterium in 1% casamino acids (vitamin free) resulted in cells which were devoid of the superficial layers, and negative staining of these cells revealed an amorphous precipitate together with a vesicular outer membrane component extruding from their surfaces into the medium. Addition of either 1 mMCa2+or 1 mMSr2+to the growth medium produced the typical regularly structured cell surface, whereas addition of equal concentrations of Li+, Na+, K+, Mg2+, Ba2+, Mn2+, Fe3+, or three polyamines produced the structureless surface.

ISSN:0008-4166    

DOI:10.1139/m76-183

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

An indirect microhemagglutination assay (IHA) was devised because of a need to provide an alternative test to complement fixation (CF) for varicella–zoster (V–Z) antibody determination. Human erythrocytes were sequentially treated with 2% glutaraldehyde, 0.04% tannic acid, and 2% pyruvic aldehyde then exposed to sonicated V–Z infected cells. This same tanning procedure was suitable for herpes simplex and Epstein-Barr virus antigen attachment but unsatisfactory for several non-herpes-group viruses. V–Z antibody titres determined by IHA were generally 2 to 16 times higher than CF titres. Cross-reaction with herpes simplex antibody was minimal.

ISSN:0008-4166    

DOI:10.1139/m76-184

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Procedures for sectioning fungal fructifications in host tissues or on artificial media are described, which allow observation of internal structures by scanning electron microscopy. Perithecia ofCeratocystis fimbriataandPhyllachora graminis, and telia ofPuccinia xanthiishowed excellent preservation of exposed structures in sections which were osmium-coated before being dried. While similar preservation was obtained in sectioned acervuli ofLecanosticta acicolaandMarssonina juglandisand in pycnidia ofDothiorella ribisandPhomopsis occulta, the mucilaginous substances produced in these fructifications precluded observation of conidiophores. Extraction of mucilage from these sections was accomplished by periodic acid and dilute KOH treatments, followed by an osmium-coating procedure. In such preparations, mucilage was removed, internal structures were preserved, and pertinent characteristics of conidiogenous cells were resolved.

ISSN:0008-4166    

DOI:10.1139/m76-185

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The optimal pH and temperature ofp-coumarate decarboxylase were 6.0 and 23 °C, respectively. The enzyme activity was reduced to three quarters by heat treatment at 35 °C for 5 min and by half at 25 °C in 24 h, but kept almost unchanged at −20 °C at least for l0 days. The activity was not inhibited by potassium cyanide, sodium diethyldithiocarbamate, ethylenediaminetetraacetic acid disodium salt, or sodium citrate at 10 mMconcentration, but was inhibited byp-chloromercuribenzoate or iodoacetate at 0.1 mM, the inhibition by the former being prevented to a great extent by the presence of reduced glutathione or dithiothreitol. The activity was inhibited by maleic acid, cinnamic acid, orp-methoxycinnamic acid, but not by fumaric acid, acrylic acid,p-hydroxystyrene, furcatin,p-hydroxyphenylacetic acid, or phloretic acid. An unsubstitutedp-hydroxy group on the benzene ring and an acrylic acid side chain were required for the enzyme activity.Kmvalue fortrans-p-coumaric acid was about 6.5 × 10−4 M.

ISSN:0008-4166    

DOI:10.1139/m76-186

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The role of NaCl in the growth ofVibrio parahaemolyticusstrain A-55 was investigated. Maximal growth was obtained at 0.5 MNaCl in a synthetic medium. Na+could not be replaced for growth by any other cations or substances. When the medium was kept isotonic with 0.5 MNaCl by the addition of sucrose, good growth was obtained with 0.1 MNaCl. By reducing the osmotic pressure and decreasing the NaCl concentration from 0.5 Mto 0.1 M, the same growth yield was obtained as when using a medium containing 0.02 MNaCl and 0.08 MLiCl. This was not the case with sucrose. Therefore, it is concluded that ionic strength and osmotic pressure are important environmental factors affecting growth. The minimal essential requirement for Na+for growth ofV.parahaemolyticuswas 0.003 M, because this was never replaced with any other cations and agents. Hence, requirement for Na+for growth involves a specific requirement for Na+, ionic strength, and osmotic pressure, respective concentrations being 0.003 M, 0.047 M, and 0.45 M. Osmotic support was required for growth when the concentration of NaCl was decreased to 0.05 M. The effect of ionic strength of monovalent cations other than Na+on growth was examined at 0.003 MNaCl. Among LiCl, NH4Cl, KCl, and RbCl, Li+was the most accelerative for growth in the synthetic medium.

ISSN:0008-4166    

DOI:10.1139/m76-187

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The existence of sexual hormone inDictyostelium purpureumwas revealed when the extracellular medium from certain strains (Dp6 or Dp7) induced macrocyst formation when added to cells of the opposite mating type (Dp2). Our results suggest that mating in cellular slime moulds may involve a secreter–responder system whereby one mating-type strain (Dp6 or Dp7) releases sexual hormone while the opposite strain (Dp2) responds. However, the existence of a hormone released by the responding strain has not been completely ruled out by our experiments. The sexual hormones of cellular slime moulds appear to be species-specific since hormone fromD.purpureumcannot induce macrocyst formation in responder strains ofD.discoideumand hormone fromD.discoideumhas no effect onD.purpureumcells.

ISSN:0008-4166    

DOI:10.1139/m76-188

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Systematic examinations were made of factors influencing bacteriorhodopsin formation during the growth ofHalobacterium halobium. Light-induced adenosine triphosphate (ATP) production and [14C]proline uptake were used as measures of functional ability of the purple membrane. Maximum bacteriorhodopsin formation occurred under growth conditions of illumination and limited aeration. The purple membrane – ATP production system did not confer an appreciable growth advantage. Growth in the dark or with adequate aeration partially suppressed bacteriorhodopsin formation and the effects were additive. Nicotine effectively inhibited bacteriorhodopsin formation. A rapid synthesis of functional pigment occurred when washed suspensions of cells which had been grown under illumination with nicotine present were incubated under dark, aerobic conditions. The alleviation of this nicotine inhibition was not blocked by chloramphenicol or bacitracin. Bacteriorhodopsin formation was negligible when washed suspensions of cells from dark, limited aeration or light, adequate aeration cultures were incubated in the light with limited aeration. A nutritionally complex medium was needed to elicit appreciable bacteriorhodopsin formation by the cells from the dark or adequately aerated cultures. Bacitracin partially inhibited this bacteriorhodopsin formation by cells from the light, adequately aerated culture.

ISSN:0008-4166    

DOI:10.1139/m76-189

出版商:NRC Research Press    

年代:1976

数据来源: NRC