Escherichia coli lipopolysaccharide administration transiently suppresses luteal structure and function in diestrous cows

The objective was to characterize the effects of Escherichia coli lipopolysaccharide (LPS) endotoxin (given i.v.) on luteal structure and function. Seven nonlactating German Holstein cows, 5.1±0.8 years old (mean±s.e.m.), were given 10 ml saline on day 10 (ovulation=day 1) of a control estrous cycle. On day 10 of a subsequent cycle, they were given 0.5 μg/kg LPS. Luteal size decreased (from 5.2 to 3.8 cm2, P≤0.05) within 24 h after LPS treatment and remained smaller throughout the remainder of the cycle. Luteal blood flow decreased by 34% (P≤0.05) within 3 h after LPS and remained lower for 72 h. Plasma progesterone (P4) concentrations increased (P≤0.05) within the first 3 h after LPS but subsequently declined. Following LPS treatment, plasma prostaglandin (PG) F metabolites concentrations were approximately tenfold higher in LPS-treated compared with control cows (9.2 vs 0.8 ng/ml, P≤0.05) within 30 min, whereas plasma PGE concentrations were nearly double (P≤0.05) at 1 h after LPS. At 12 h after treatment, levels of mRNA encoding Caspase-3 in biopsies of the corpus luteum (CL) were increased (P≤0.05), whereas those encoding StAR were decreased (P≤0.05) in cattle given LPS vs saline. The CASP3 protein was localized in the cytoplasm and/or nuclei of luteal cells, whereas StAR was detected in the cytosol of luteal cells. In the estrous cycle following treatment with either saline or LPS, there were no significant differences between groups on luteal size, plasma P4 concentrations, or gene expression. In conclusion, LPS treatment of diestrus cows transiently suppressed both the structure and function of the CL.

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Micro-analysis of pure deoxyribonucleic acid-dependent ribonucleic acid polymerase from Escherichia coli. Action of heparin and rifampicin on structure and function

Biochemical Journal ◽

10.1042/bj1170623 ◽

1970 ◽

Vol 117 (3) ◽

pp. 623-631 ◽

Cited By ~ 35

Author(s):

Volker Neuhoff ◽

Wolf-Bernhard Schill ◽

Hans Sternbach

Keyword(s):

Escherichia Coli ◽

Rna Polymerase ◽

Rna Synthesis ◽

Deoxyribonucleic Acid ◽

Structure And Function ◽

Disc Electrophoresis ◽

Inhibitory Mechanism ◽

And Function ◽

Micro Analysis ◽

Template Complex

By using micro disc electrophoresis and micro-diffusion techniques, the interaction of pure DNA-dependent RNA polymerase (EC 2.7.7.6) from Escherichia coli with the template, the substrates and the inhibitors heparin and rifampicin was investigated. The following findings were obtained: (1) heparin converts the 24S and 18S particles of the polymerase into the 13S form; (2) heparin inhibits RNA synthesis by dissociating the enzyme–template complex; (3) rifampicin does not affect the attachment of heparin to the enzyme; (4) the substrates ATP and UTP are bound by enzyme loaded with rifampicin; (5) rifampicin is bound by an enzyme–template complex to the same extent as by an RNA-synthesizing enzyme–template complex. From this it is concluded that the mechanism of the inhibition of RNA synthesis by rifampicin is radically different from that by heparin. As a working hypothesis to explain the inhibitory mechanism of rifampicin, it is assumed that it becomes very firmly attached to a position close to the synthesizing site and only blocks this when no synthesis is in progress.

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Influence of High Pressure on the Dimerization of ToxR, a Protein Involved in Bacterial Signal Transduction

Applied and Environmental Microbiology ◽

10.1128/aem.02028-08 ◽

2008 ◽

Vol 74 (24) ◽

pp. 7821-7823 ◽

Cited By ~ 14

Author(s):

Kai Linke ◽

Nagarajan Periasamy ◽

Matthias Ehrmann ◽

Roland Winter ◽

Rudi F. Vogel

Keyword(s):

Escherichia Coli ◽

Signal Transduction ◽

High Pressure ◽

Structure And Function ◽

Transmembrane Segments ◽

Bacterial Signal Transduction ◽

Reporter Strains ◽

And Function ◽

First Time

ABSTRACT High hydrostatic pressure (HHP) is suggested to influence the structure and function of membranes and/or integrated proteins. We demonstrate for the first time HHP-induced dimer dissociation of membrane proteins in vivo with Vibrio cholerae ToxR variants in Escherichia coli reporter strains carrying ctx::lacZ fusions. Dimerization ceased at 20 to 50 MPa depending on the nature of the transmembrane segments rather than on changes in the ToxR lipid bilayer environment.

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