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Updated: Jul 22, 2026

Electron Cryotomography of Bacterial Cells
Published on: May 6, 2010
Transmission electron microscopy studies of Moraxella (Branhamella) catarrhalis
M Fitzgerald1, R Mulcahy, S Murphy
1Department of Biological Sciences, Dublin Institute of Technology, Ireland.
Abstract:
A trypsin-sensitive 200-kDa protein has been reported to be exclusively associated with haemagglutinating isolates of Moraxella (Branhamella) catarrhalis. Transmission electron microscopy studies revealed that haemagglutination by M. catarrhalis to both human and rabbit erythrocytes was mediated by a trypsin-sensitive outer fibrillar coat. This fibrillar layer was absent on non-haemagglutinating isolates examined. Immuno-electron microscopy, using a polyclonal antiserum containing antibodies to the 200-kDa protein as a probe, showed that the 200-kDa protein is present on the outer fibrillar layer of the bacterium. These findings suggest that the haemagglutinin of M. catarrhalis is a 200-kDa protein present on the outer fibrillar coat.
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