ABSTRACT
The temperature-sensitive hemagglutinin (Tsh, 140 kDa) produced by Escherichia coli is cleaved into a fragment (106 kDa) containing mucinase activity, and an agglutinin fragment (33 kDa). By incorporating mucins into SDS-PAGE gels stained by Schiff's periodic acid, we could simultaneously detect about 0.5 microg of mucinase activity and the fragment molecular mass.
Subject(s)
Adhesins, Escherichia coli/metabolism , Electrophoresis, Polyacrylamide Gel/methods , Escherichia coli/metabolism , Polysaccharide-Lyases/metabolism , Hemagglutinins/metabolism , Mucins/metabolismABSTRACT
Several virulence genes of avian Escherichia coli were detected in 200 colibacillosis isolates from our region by PCR. However, the genes sfaDE and facA were not detected in that study. In this work we correct those data, showing by colony hybridization that sfaDE and facA are present in 40% and 30% of those isolates, respectively.
Subject(s)
Chickens , Escherichia coli Infections/veterinary , Escherichia coli/genetics , Escherichia coli/pathogenicity , Poultry Diseases/microbiology , Animals , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Escherichia coli/isolation & purification , Escherichia coli Infections/microbiology , Fimbriae, Bacterial/chemistry , Fimbriae, Bacterial/genetics , Nucleic Acid Hybridization , Polymerase Chain Reaction/veterinary , VirulenceABSTRACT
Avian pathogenic Escherichia coli, the causative agent of colibacillosis, harbors several putative virulence genes. In this study we examined by polymerase chain reaction (PCR) the presence of 16 of those genes in 200 colibacillosis isolates from our region. The seven virulence genes iutA, iss, cvaC, tsh, papC, papG and felA were detected significantly more often amongst colibacillosis isolates than in fecal isolates from healthy birds, thereby confirming their worldwide occurrence and possible pathogenic role in colibacillosis. However, several of those genes were not detected in many colibacillosis isolates, and none of them were detected in 27.5% of those isolates, which suggests that variants of those genes and yet undetected virulence factors should be searched for.
Subject(s)
Chickens , Escherichia coli Infections/veterinary , Escherichia coli/genetics , Escherichia coli/pathogenicity , Poultry Diseases/microbiology , Animals , DNA, Bacterial/analysis , Escherichia coli Infections/microbiology , Feces/microbiology , Liver/microbiology , Polymerase Chain Reaction/veterinary , Trachea/microbiology , Virulence/geneticsABSTRACT
In this study, we determined the occurrence of the tsh gene among 305 Escherichia coli isolates from chickens by means of the polymerase chain reaction and agglutination of chicken erythrocytes; 200 of those isolates were obtained from chickens with colisepticemia, 52 isolates were from lesions of cellulitis, and 53 were from feces of normal chickens. The tsh gene was found in 79 (39.5%) isolates from colisepticemia, in 10 (19%) cellulitis-derived E. coli isolates, and in two (3.8%) fecal isolates. Among the tsh+ strains, 68 (86%) isolates from colisepticemia and nine (90%) from cellulitis agglutinated chicken erythrocytes in the presence of mannose, after growing the strains on colonization factor antigen agar plates at 26 C, which confirms a correlation between mannose-resistant hemagglutination and expression of hemagglutinin Tsh. These results show, for the first time, the presence of the gene tsh in cellulitis-derived E. coli isolates; the high frequency of this gene among avian pathogenic E. coli isolates in Brazil indicates that its putative role as a virulence factor should be studied more thoroughly.
Subject(s)
Adhesins, Escherichia coli/isolation & purification , Chickens , Escherichia coli Infections/veterinary , Escherichia coli/pathogenicity , Hemagglutinins/isolation & purification , Poultry Diseases/microbiology , Animals , Bacteremia/microbiology , Bacteremia/veterinary , Cellulitis/microbiology , Cellulitis/veterinary , Escherichia coli/genetics , Escherichia coli Infections/microbiology , Feces/microbiology , Hemagglutination Tests/veterinary , Polymerase Chain Reaction/methods , Polymerase Chain Reaction/veterinary , Temperature , Virulence/geneticsABSTRACT
Chronic exposure to manganese (Mn) positively correlates with the occurrence of Parkinsonism but little is known about mechanisms of its neurotoxicity. In the present study, we determined the clearance of Mn from rat substantia nigra after its nigral injection and correlated it with the establishment of apomorphine-induced rotational behaviour and loss of striatal tyrosine hydroxylase (TH) immunoreactivity. Our results suggest that Mn is slowly cleared from the substantia nigra, following a first-order kinetics with a t(1/2) of 3 days. Appearance of apomorphine-induced rotational behaviour and loss of TH immunoreactivity within the striatum follows metal clearance were both detected 24 hours after intra-nigral Mn microinjection and maximal 72 hours after injection. The present data suggest that the cellular mechanisms induced by Mn and leading to dopaminergic cell death, occurred shortly after its injection and that the metal concentration needs to reach a threshold value to induce neurotoxic effects. This would indicate that nigral damages are a direct consequence of Mn accumulation.
