摘要:

Aplysiagonad lectin, isolated from the molluscAplysia depilans, was successfully conjugated to colloidal gold and used for ultrastructural detection of galacturonic acids in some pathogenic fungi. These sugar residues were found to occur in the fibrillar sheath surrounding hyphal cells ofAscocalyx abietinaand in intravacuolar dense inclusions of this fungus spores. In hyphae and spores ofOphiostoma ulmi, galacturonic acids were detected mainly in the outermost wall layers. In contrast, these saccharides appeared associated with the innermost wall layers and especially the plasma membrane ofVerticillium albo-atrumcells. Galacturonic acids were found to be absent in cells ofFusarium oxysporumf.sp.radicis-lycopersiciandCandida albicans. These cytochemical data indicate therefore that a heterogeneity in wall composition exists between ascomycete fungi. The significance of the presence of galacturonic acids in the cell walls of certain fungi is still open to question.Key words: galacturonic acid, fungi, gold labeling,Aplysia depilansgonad lectin.

ISSN:0008-4166    

DOI:10.1139/m89-054

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

This study identified and characterized four cadmium-resistant mutants ofNeurospora crassa. One of these mutants maps to linkage group II and the other three map to linkage group VII, whereas a naturally occurring resistant trait in a strain from Japan resides at a distinct but unmapped locus. Transport of cadmium intoNeurosporacells occurs by more than a single uptake system and involves both energy-dependent and -independent components. The resistant mutants transport cadmium in the same manner as does the cadmium-sensitive wild-type strain. Cadmium resistance in these mutants does not appear to result from an increase in cytosolic heat-stable cadmium-binding proteins. Cadmium does not induce the typical heat-shock response in conidia. Under various growth conditions, each of the mutants exhibited morphological alterations, possibly involving the cell wall or plasma membrane.Key words: cadmium,Neurospora, transport, resistant mutants.

ISSN:0008-4166    

DOI:10.1139/m89-055

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Production of inhibitory substances by strains of theStreptococcus mutansgroup is well documented, but the nature of the substances implied is often unknown. Of nine laboratory strains known to produce inhibitory substances, the optimal conditions for producing inhibition zones on solid media were found to vary between strains but good production was generally obtained on all-purpose media with Tween 80 at 37 °C after 2–4 days of aerobic incubation.Streptococcus sanguisNy101 was found to be more sensitive thanStreptococcus rattusLG-1 to all inhibitory substances produced by theS.mutansstrains tested. While all strains showed some inhibition, only six showed inhibition after neutralization; arginine incorporated in agar at 0.75% completely eliminated all inhibition zones. However 1% arginine in the overlays did not affect the production of inhibition zones by strains ofS.mutansC67-1, Ny257, Ny266, and T8. These strains were shown to elaborate (in a reproducible fashion) inhibitory substances which were not organic acids. Inhibitory activity was never obtained in liquid preparations, except for strains Ny257 and T8 where it was found to be very unstable.Key words: mutacin, bacteriocin, inhibitory substance,Streptococcus mutans.

ISSN:0008-4166    

DOI:10.1139/m89-056

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The patterns of protein synthesis associated with three sequential stages in protoplast morphogenesis (spindle-shaped, early fusion sphere, and late fusion sphere protoplasts) of the fungusEntomophaga aulicaewere studied using both one-dimensional gels with general protein staining and two-dimensional gels with [35S]methionine protein labelling and fluorography. A total of 332 proteins were observed with 63.5% (211) common to all three developmental stages. Of the individual totals, 3.3% (8 out of 245), 7.3% (22 out of 301), and 4.5% (13 out of 286) of the proteins were unique to the spindle-shaped, early fusion sphere, and late fusion sphere protoplasts, respectively. The molecular mass and pI distribution profiles for early fusion sphere protoplast proteins are discussed.Key words: protein synthesis, stage-specific proteins, fungal protoplasts,Entomophaga aulicae.

ISSN:0008-4166    

DOI:10.1139/m89-057

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

By use of experimental microcosms, it was demonstrated that the survival ofEscherichia coliin nutrient-free seawater depended on the age of cells and on some physicochemical conditions during their prior growth. Cells grown in a bacteriological medium, with an acid or an alkaline pH, at high temperature (44 °C), or in the absence of oxygen were more sensitive to exposure to seawater of low nutrient content. In contrast, some complex media allowed production of cells adapting more rapidly to seawater. Cells grown in urine were far more sensitive than those grown in all bacteriological media tested. The sensitivity of all cells was highest when they were harvested during the early exponential phase of growth.Key words:Escherichia coli, seawater, growth, survival.

ISSN:0008-4166    

DOI:10.1139/m89-058

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Surface cultures ofPenicillium cyclopium, grown in a closed aeration system on a semisolid minimal medium with 2-keto-glutarate, glutamate or glucose as carbon source, produced ethylene in two phases. The first was associated with aerial hyphae formation; the second, with conidiation. The maximum rate of ethylene synthesis coincided with intensive oxygen consumption whereas the cessation and reutilization of ethylene occurred together with a low respiration rate. After the removal of the aerial mycelium, vegetative hyphae continued ethylene production up to 50% of the value reached in intact cultures. Neither detached aerial mycelium with penicilli nor pure conidia produced ethylene. The content of ethylene in the medium of a producing culture was four-fold higher than would correspond to its concentration in the atmosphere above the culture. In the upper agar layer (1.25 mm), a high pH (8.8) and 30 mMwas found, presumably because of mycelium autolysis. The pH in the layer 3 mm below the surface was 2.4. In lower layers (up to 2 mm beneath the last vegetative hyphae), ammonium ions were completely depleted. The phosphate content was inversely proportional to the hyphal density. We suggest that the low phosphate concentration (0.06 mM) in the upper layers permitted ethylene formation.Key words: conidiation, vegetative hyphae, ethylene, ion gradients, surface culture.

ISSN:0008-4166    

DOI:10.1139/m89-059

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Putrefactive anaerobe 3679 (Clostridium sporogenes), a gram-positive bacterium, was examined by light and electron microscopy during normal growth and in a medium containing sorbate (50 mM, pH 6.5), hydrochloric acid (pH of medium adjusted from 7 to 5 with HCl), or nitrite (1 mM, pH 7). During the early exponential growth phase, untreated cells were filamentous and nonseptate, but became septate later and divided when the culture entered the stationary phase. Untreated short and filamentous cells had a double-layered cell wall. Sorbate-treated cells were usually filamentous and nonseptate, but with distorted shapes characterized by numerous bends and bulges. Septation, when present, resulted in minicells. The inner cell wall appeared to be thickened and the outer wall was absent in many areas. Acid-treated cells were similar to sorbate-treated cells but contained septa. Considerable cellular debris was present in the suspension. Nitrite-treated cells were also filamentous, bent, and bulged but the cell wall appeared normal. Considerable cellular debris was also present in suspensions of nitrite-treated cells. Changes in morphology are discussed in relation to possible mechanisms of cell growth regulation and the inhibitory action of sorbate, acid, and nitrite.Key words: putrefactive anaerobe 3679, sorbate, hydrochloric acid, nitrite.

ISSN:0008-4166    

DOI:10.1139/m89-060

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Production of cephems (predominantly cephamycin C) byStreptomyces clavuligerusgrown in chemically defined medium supplemented with 120 mM NH4Cl was sharply reduced. This concentration of ammonium ions in the medium repressed δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine (ACV) synthetase formation by about 75%. Of the other cephalosporin synthases, cyclase was repressed by 70%, expandase by 50%, and epimerase only to a very small extent. Inhibition of the action of ACV synthetase was only slight in the presence of 100 mM NH4Cl. Repression of ACV synthetase, cyclase, and expandase appears to be the major factors contributing to the negative effect of ammonium onS.clavuligerusNRRL 3585. ACV synthetase is probably the rate-limiting step of cephalosporin biosynthesis in this strain.Key words: β-lactam biosynthesis, antibiotic biosynthesis, cephalosporins,Streptomyces clavuligerus, ACV synthetase.

ISSN:0008-4166    

DOI:10.1139/m89-061

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

DiazotrophicAlcaligenes faecalisstrain A15 isolated from rice roots is associated with rice roots and resides in the mucilage layer. On examination by light and electron microscopy, about 10% of the bacteria that accumulated on the surface entered the root cells. Some bacteria were observed to penetrate the cell wall. By using a10B α-track technique, the presence of bacteria inside the root was also demonstrated after the rice plants were inoculated withA.faecalis. This was further supported by results of an immunofluorescence study. Both single cells and protoplasts were isolated from rice root and its callus. Transmission and scanning electron microscopy showed thatA.faecalisgrew inside the root cell. Callus, developed from rice root cells inoculated with this bacterium, grew well in nitrogen-free culture medium, while it died within 30 days without inoculation. Nitrogen fixation in the callus was confirmed by15N tracer methodology and the rate ranged from 18.5 to 35.5 μg N fixed/g dry weight callus per day.Key words:Alcaligenes faecalis, endorhizospheric nitrogen fixation, rice–bacteria symbiont.

ISSN:0008-4166    

DOI:10.1139/m89-062

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Intact cells of several bacterial species were tested for their ability to bind human transferrin and lactoferrin by a solid-phase binding assay using horseradish peroxidase conjugated transferrin and lactoferrin. The ability to bind lactoferrin was detected in all isolates ofNeisseriaandBranhamella catarrhalisbut not in isolates ofEscherichia coliorPseudomonas aeruginosa. Transferrin-binding activity was similarly detected in most isolates ofNeisseriaandBranhamellabut not inE.coliorP.aeruginosa. The expression of transferrin- and lactoferrin-binding activity was induced by addition of ethylenediamine di-o-phenylacetic acid and reversed by excess FeCl3, indicating regulation by the level of available iron in the medium. The transferrin receptor was specific for human transferrin and the lactoferrin receptor had a high degree of specificity for human lactoferrin in all species tested. The transferrin- and lactoferrin-binding proteins were identified after affinity isolation using biotinylated human transferrin or lactoferrin and streptavidin–agarose. The lactoferrin-binding protein was identified as a 105-kilodalton protein in all species tested. Affinity isolation with biotinylated transferrin yielded two or more proteins in all species tested. A high molecular mass protein was observed in all isolates, and was of similar size (approximately 98 kilodaltons) in all species ofNeisseriabut was larger (105 kilodaltons) inB.catarrhalis.Key words: iron,Neisseria, transferrin, lactoferrin, receptor.

ISSN:0008-4166    

DOI:10.1139/m89-063

出版商:NRC Research Press    

年代:1989

数据来源: NRC