8 research outputs found
A two-component regulatory system modulates twitching motility in Dichelobacter nodosus
© 2015 Elsevier B.V. All rights reserved. Dichelobacter nodosus is the essential causative agent of footrot in sheep and type IV fimbriae-mediated twitching motility has been shownto be essential for virulence.Wehave identified a two-component signal transduction system (TwmSR) that shows similarity to chemosensory systems from other bacteria. Insertional inactivation of the gene encoding the response regulator, TwmR, led to a twitching motility defect, with the mutant having a reduced rate of twitching motility when compared to the wild-type and a mutant complemented with the wild-type twmR gene. The reduced rate of twitching motility was not a consequence of a reduced growth rate or decreased production of surface located fimbriae, but video microscopy indicated that it appeared to result from an overall loss of twitching directionality. These results suggest that a chemotactic response to environmental factors may play an important role in the D. nodosus-mediated disease process
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
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Luminescent (metallo-supramolecular) cross-linked lanthanide hydrogels from a btp (2,3-bis(1,2,3-triazol-4-yl)picolinamide) monomer give rise to strong Tb(iii) and Eu(iii) centred emissions
Acknowledgements: We thank the School of Chemistry TCD, Science Foundation Ireland (SFI PI Awards 10/IN.1/B2999 and 13/IA/1865 to TG). TG would also like to thank the SFI funded AMBER Centre for financial support (SFI 12/RC/2278_P2). EPSRC EP/S009000/1 is acknowledged for support of Dr Niamh Willis-Fox.The synthesis and study of the lanthanide luminescent 2,3-bis(1,2,3- triazol-4-yl)picolinamide (btp) based hydrogels F1 and F2 is described where Tb(iii) or Eu(iii) are also used to crosslink the btp units within the polymers.</jats:p