摘要:

A rhabdovirus, Mn 936-77, was isolated from a pool of twoCulex tarsaliscollected on August 16, 1977, from Morris, Manitoba. Isolate Mn 936-77 was not pathogenic for suckling Swiss white mice inoculated by the intracerebral route. The virus propagated in three vertebrate cell lines (Vero, primary chick embryo, mouse neuroblastoma), but apparently not inAedes albopictusC6/36 cells. Isolate Mn 936-77 did not react by amplified enzyme-linked immunosorbant assay with 230 viruses of proven or possible arbovirus etiology or by immunofluorescence with 88 members of the family Rhabdoviridae. Isolate Mn 936-77 appears to be a newly discovered virus for which the name Manitoba virus is proposed.Key words: arbovirus,Culex tarsalis, rhabdovirus, Manitoba virus.

ISSN:0008-4166    

DOI:10.1139/m91-053

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The growth supplement requirements in minimal medium, the identity of metabolic intermediates accumulated, and the activity of tryptophan biosynfhetic enzymes detectable in cell extracts allowed thetrpmutations in 10 auxotrophic strains ofStreptomyces venezuelaeISP5230 to be determined. Three strains contained lesions in thetrpAand two in thetrpBsubunits of tryptophan synthetase; two other strains were either double (trpA,trpB) mutants or contained a polar mutation in one of the subunit genes. Two strains withtrpCmutations and one with atrpDmutation were also identified. When considered with information about the relative location of the auxotrophic markers obtained in this and earlier studies, the results indicated thattrpA,trpB, andtrpCare clustered nearhisAandhisB, whiletrpDis in a separate position nearnicB. The arrangement resembles that of the comparable genes inStreptomyces coelicolorA3(2).Key words: tryptophan auxotrophs,Streptomyces venezuelae, mutation loci, tryptophan biosynthesis genes.

ISSN:0008-4166    

DOI:10.1139/m91-054

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The relationships of 10 binucleateRhizoctoniaisolates used as biocontrol agents of rhizoctonia crown and root rot of sugar beet in Ohio to described binucleateRhizoctoniaanastomosis systems were investigated. Ten Ohio binucleateRhizoctonia(Ohio BNR) isolates, paired in all combinations, cross anastomosed with one another, indicating that all belong to the same anastomosis group. Four representative Ohio BNR isolates failed to anastomose with any tester isolates of theCeratobasidiumanastomosis grouping system, indicating that none belong in that system. However, all 10 Ohio BNR isolates anastomosed with an AG-B (o) tester isolate (binucleateRhizoctoniaanastomosis grouping system), indicating that the Ohio agents belong in this anastomosis grouping system and to the (o) intraspecific group of AG-B. None of the Ohio BNR isolates anastomosed with either of the other two intraspecific group tester isolates (AG-Ba, AG-Bb) of the AG-B group. Moreover, the AG-B intraspecific group tester isolates, AG-Ba, AG-Bb, AG-B (o), self-anastomosed but did not cross anastomose with one another. Variations in cultural characteristics noted among the 10 Ohio BNR isolates indicated that considerable heterogeneity exists within these AG-B (o) isolates.Key words: binucleateRhizoctonia, anastomosis, rhizoctonia crown rot, sugar beet.

ISSN:0008-4166    

DOI:10.1139/m91-055

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The 1600-bp (base pair) fragment encoding a portion of the nalidixic acid resistant DNA gyrase, subunit B, was characterized to determine what parameters effect transformation in the gonococcus. When this DNA (pSY2) was isolated fromEscherichia coli, it was able to transform a variety of gonococcal strains to resistance to nalidixic acid via DNA-mediated transformation, irrespective of their restriction–modification phenotype. Nalidixic acid resistant transformants contained no plasmid DNA sequences that corresponded to the vector, as measured by plasmid screening procedures and colony hybridization techniques. Supercoiled and linear DNA transformed the gonococcus at the same efficiency. DNA fragments as small as 615 bp were able to transform the gonococcus. The presence of a 10-bp uptake sequence enhanced a DNA fragment's ability to transform the gonococcus by four orders of magnitude. When the fragment encoding the nalidixic acid resistant DNA gyrase was subcloned into M13mp18, both the replicative form and the single-stranded form of the phage were able to transform the gonococcus to nalidixic acid resistance.Key words: sequence-specific uptake, gyrase, restriction and modification.

ISSN:0008-4166    

DOI:10.1139/m91-056

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

Polyamine synthetic activity was compared among the three eubacteriaHalococcus acetoinfaciens(IAM 12094),Halococcus agglomeratus(IAM 12095), andHalococcus nondenitrificans(IAM 12096). Putrescine was produced by decarboxylation of ornithine but not from agmatine in the three species.N-Carbamylputrescine was converted to putrescine in the latter two species. Lysine decarboxylase activity was found only inH.acetoinfaciens, which contains aminopropylcadaverine, aminopentylnorspermidine, andN,N′-bis(3-aminopropyl)cadaverine in addition to spermidine, spermine, and thermospermine. InH.acetoinfacienswhen diaminopropane was added to the culture medium, both norspermidine and norspermine were synthesized; when homospermidine was added, aminopropylhomospermidine was formed. In contrastH.agglomeratusandH.nondenitrificanssynthesize putrescine, spermidine, and trace amounts of spermine but cannot synthesize other triamines and tetraamines from diamines and triamines supplemented to the culture medium.Key words:Halococcus, decarboxylase, polyamines, aminopropyltransferase, inhibitors, aminopropylcadaverine.

ISSN:0008-4166    

DOI:10.1139/m91-057

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

Two new species ofSyncephalis,Syncephalis torpedosporaandSyncephalis parvula, are described. They were isolated from agricultural soil in Germany and have been maintained as haustorial mycoparasites onMortierella alpina.Syncephalis torpedosporabears one-spored merosporangia,S.parvulatwo-spored merosporangia on the upper hemisphere of the globose fertile vesicle. Both are relatively small members of the genusSyncephalis.Key words:Mucorales, mycoparasitism,Piptocephalidaceae,Syncephalis, Zygomycetes.

ISSN:0008-4166    

DOI:10.1139/m91-058

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The presence of peroxisomes and peroxisomal enzyme activities were investigated in the oleaginous yeastApiotrichum curvatumATCC 20509 (formerlyCandida curvataD.) Catalase, a marker enzyme for peroxisomes, was measured in cell-free extracts prepared by sonication. The nature of the carbon and nitrogen sources in the growth medium greatly affected catalase activity. Cells grown on corn oil had high specific activity of catalase, but those grown on glucose, sucrose, or maltose had low specific activity. High specific activity of catalase was measured in cultures grown on media that supported poor growth (with soluble starch as carbon source or with methylamine, urea, or asparagine as nitrogen source). Peroxisomes from cells grown on corn oil were separated from other subcellular fractions in a discontinuous sucrose gradient. Major peaks of activity of fatty acid beta-oxidation and of two key enzymes in the glyoxylate cycle were found in fractions containing peroxisomes, but not in fractions corresponding to the mitochondria. Peroxisomal beta-oxidation showed equivalent activity with palmitoyl CoA orn-octanoyl CoA as substrate. Mitochondria did not seem to contain NAD-linked glutamate dehydrogenase. Peroxisomes with a homogeneous matrix and core surrounded by a single-layer membrane were observed with an electron microscope in cells grown on corn oil, but not in those grown on glucose. Staining with 3,3′-diaminobenzidine revealed that catalase activity was located in peroxisomes. Peroxisomes in this oleaginous yeast play important roles in lipid metabolism.Key words: lipid, peroxisomes, oleaginous,Apiotrichum curvatum, catalase, beta-oxidation, glyoxylate cycle.

ISSN:0008-4166    

DOI:10.1139/m91-059

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The stability of the outer-membrane proteins and antigens of a strain ofBacteroides intermedius(VP1 8944 group genotype II) grown in contious culture at varying pH and growth rates (D = 0.025–0.2 h−1, pH 6.0–7.3) has been measured. The membranes showed nine major proteins (> 67–19.55 kilodaltons) and six major antigens (65–28 kilodaltons). Membrane proteins and antigens were stable under the conditions tested; the major proteins were detected in all membranes, and the antigen profiles tested with different antisera showed maximum similarities of 82–95%. Differences did occur in the amounts of membrane proteins synthesized; cells at high growth rates and those growing on the surfaces in the chemostat showed increased amounts of two proteins (40 and 32 kilodaltons) and possibly novel proteins of 24 and 25 kilodaltons. In addition, these membranes reflected increased synthesis or a change to increased reactivity of antigens between 20.5 and 24 kilodaltons. The results indicate stability of the expression of outer-membrane proteins and antigens in environments of differing pH and under different growth rates. However, the amount of these molecules synthesized can vary, and increases in certain proteins and antigens occur as the growth rate increases and the organisms grow on surfaces.Key words:Bacteroides intermedius, outer-membrane antigens, antigenic stability, chemostat culture, outer-membrane profiles.

ISSN:0008-4166    

DOI:10.1139/m91-060

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

Cell surface proteins obtained by alkaline extraction from isolated cell walls ofMortierella pusillaandM.candelabrum, host and nonhost, respectively, of the mycoparasitePiptocephalis virginiana, were tested for their ability to agglutinate mycoparasite spores. The host cell wall protein extract had a high agglutinating activity (788 agglutination units/mg) compared with that of the nonhost extract (21 agglutination units/mg). Sodium dodecyl sulfate – polyacrylamide gel electrophoresis of the crude extract of the host revealed four bands,a,b,c, andd, with respectiveMrof 117 000, 100 000, 85 000 and 64 000; these bands except for a faint bandc, were absent from the nonhost surface. Deletion of proteinsborcfrom the crude protein extract of the host significantly reduced its agglutinating activity. Proteinsbandc, purified by a series of procedures, were shown to be glycoproteins with glucose andN-acetylglucosamine as major saccharides. The agglutinating activity of a mixture of pure proteinsbandcwas over 500 times that of either glycoprotein alone, suggesting an involvement of both glycoproteins in the agglutination process. Further characterization showed that the two glycoproteins were heat-resistant with respect to their agglutinin function, which could be totally inhibited by three sugars: arabinose, glucose andN-acetyglucosamine. It is suggested that glycoproteinsbandcare the two subunits of a carbohydrate-binding agglutinin present at the host cell surface and involved in agglutination and attachment of the mycoparasite germ tubes.Key words: agglutinin, attachment, cell surface, sugars, glycoproteins, mycoparasitism.

ISSN:0008-4166    

DOI:10.1139/m91-061

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

Cleavage of host defense proteins from reproductive secretions was investigated as a potential virulence mechanism forTritrichomonas foetusextracellular proteinases. Three categories of susceptibility to digestion were found among the defense proteins tested. Cleavage of fibrinogen, fibronectin, and albumin occurred rapidly with more than 50% of these digested within 30 min. Lactoferrin, immunoglobulin G1, and immunoglobulin G2 were more than 50% digested after 4 h. Transferrin, immunoglobulin M, and immunoglobulin A were the most resistant to theTritrichomonas foetusextracellular proteinases, since 50% or more of the parent molecule remained after 24 h. The responsible proteinases were classified as cysteine (thiol) proteinases because cleavage was inhibited by the cysteine proteinase specific inhibitor,trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane and not by the serine proteinase specific inhibitor, phenylmethylsulfonyl fluoride. In addition, α2-macro-globulin, but not α1-antitrypsin, inhibits the action of the proteinases. The ratio of this naturally occurring inhibitor to the quantity of proteinases released may determine whether the above substrates are cleavedin vivo. Since these substrates are implicated in iron acquisition, cell adherence, and acquired immunity,Tritrichomonas foetusproteinases are likely to play a role in host–parasite interactions.Key words: cysteine proteinase,Tritrichomonas foetus, host defense proteins, reproductive secretions.

ISSN:0008-4166    

DOI:10.1139/m91-062

出版商:NRC Research Press    

年代:1991

数据来源: NRC