82 research outputs found
Indirect measurement of the magnetocaloric effect using a novel differential scanning calorimeter with magnetic field
Get PDFCurli
are bacterial appendages involved in the adhesion of cells
to surfaces; their synthesis is regulated by many genes such as <i>csgD</i> and <i>ompR</i>. The expression of the two
curli subunits (CsgA and CsgB) in <i>Escherichia coli</i> (<i>E. coli</i>) is regulated by CsgD; at the same time, <i>csgD</i> transcription is under the control of OmpR. Therefore,
both genes are involved in the control of curli production. In this
work, we elucidated the role of these genes in the nanomechanical
and adhesive properties of <i>E. coli</i> MG1655 (a laboratory
strain not expressing significant amount of curli) and its curli-producing
mutants overexpressing OmpR and CsgD, employing atomic force microscopy
(AFM). Nanomechanical analysis revealed that the expression of these
genes gave origin to cells with a lower Young’s modulus (<i>E</i>) and turgidity (<i>P</i><sub>0</sub>), whereas
the adhesion forces were unaffected when genes involved in curli formation
were expressed. AFM was also employed to study the primary structure
of the curli expressed through the freely jointed chain (FJC) model
for polymers. CsgD increased the number of curli on the surface more
than OmpR did, and the overexpression of both genes did not result
in a greater number of curli. Neither of the genes had an impact on
the structure (total length of the polymer and number and length of
Kuhn segments) of the curli. Our results further suggest that, despite
the widely assumed role of curli in cell adhesion, cell adhesion force
is also dictated by surface properties because no relation between
the number of curli expressed on the surface and cell adhesion was
found
Indirect measurement of the magnetocaloric effect using a novel differential scanning calorimeter with magnetic field
Get PDFRisk of death or reinfarction associated with the use of selective cyclooxygenase-2 inhibitors and nonselective nonsteroidal antiinflammatory drugs after acute myocardial infarction
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