| 1. |
- Ormonde, P., et al.
(författare)
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Role of motility in adherence to and invasion of a fish cell line by Vibrio anguillarum
- 2000
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Ingår i: Journal of Bacteriology. - 0021-9193 .- 1098-5530. ; 182:8, s. 2326-2328
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Tidskriftsartikel (refereegranskat)abstract
- To understand further the role of the flagellum of Vibrio anguillarum in virulence, invasive and adhesive properties of isogenic motility mutants were analyzed by using a chinook salmon embryo cell line. Adhesion was unaffected but invasion of the cell line was significantly decreased in nonmotile or partially motile mutants, and the chemotactic mutant was hyperinvasive. These results suggest that active motility aids invasion by V. anguillarum, both in vivo and in vitro.
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| 2. |
- Hagström, Åke, et al.
(författare)
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Frequency of dividing cells a new approach to the determination of bacterial growth rates in aquatic environments
- 1979
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 37:5, s. 805-812
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Tidskriftsartikel (refereegranskat)abstract
- Frequency of dividing cells is suggested to be an indirect measureof the mean growth rate of an aquatic bacterial community. Seasonalchanges in frequency of dividing cells were found which covariatedwith the bacterial uptake of 14C-labeled phytoplankton exudates.Batch and continuous culture growth experiments, using brackishwater bacteria in pure and mixed enrichment cultures, were performedto establish a relationship between frequency of dividing cellsand growth rate. An improved technique for bacterial directcounts, using fluorescent staining and epifluorescence microscopy,is presented. Based on a 6-month survey in a coastal area ofthe Baltic Sea, the bacterial production in the photic zoneis estimated. Compared to the total primary production in thearea, the bacterial population during this period utilized approximately25% of the amount of carbon originally fixed by the primaryproducers.
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| 3. |
- O'Toole, R, et al.
(författare)
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RpoN of the fish pathogen Vibrio (Listonella) anguillarum is essential for flagellum production and virulence by the water-borne but not intraperitoneal route of inoculation.
- 1997
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Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 143 ( Pt 12)
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the involvement of RpoN in flagellum production and pathogenicity of Vibrio (Listonella) anguillarum, the rpoN gene was cloned and sequenced. The deduced product of the rpoN gene displayed strong homology to the alternative sigma 54 factor (RpoN) of numerous species of bacteria. In addition, partial sequencing of rpoN-linked ORFs revealed a marked resemblance to similarly located ORFs in other bacterial species. A polar insertion or an in-frame deletion in the coding region of rpoN abolished expression of the flagellin subunits and resulted in loss of motility. Introduction of the rpoN gene of V. anguillarum or Pseudomonas putida into the rpoN mutants restored flagellation and motility. The rpoN mutants were proficient in the expression of other proposed virulence determinants of V. anguillarum, such as ability to grow under low available iron conditions, and expression of the LPS O-antigen and of haemolytic and proteolytic extracellular products. The infectivity of the rpoN mutants with respect to the wild-type strain was unaffected following intraperitoneal injection of fish but was reduced significantly when fish were immersed in bacteria-containing water. Thus, RpoN does not appear to regulate any factors required for virulence subsequent to penetration of the fish epithelium, but is important in the infection of fish by water-borne V. anguillarum.
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