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Comparative studies of bile salts. 5 alpha-Chimaerol, a new bile alcohol from the white sucker Catostomus commersoni Lacepede.

ABSTRACT: 1. G.l.c. examination of bile alcohols prepared from the sucker Catostomus commersoni Lacépède (family Catostomidae) showed that although 5alpha-cyprinol (5alpha-cholestane-3alpha,7alpha,12alpha,26,27-pentol) was a minor constituent, the principal bile alcohol was an undescribed substance, probably present in the bile as the C-26 sulphate ester, whose i.r., n.m.r. and mass spectra agreed with the structure 5alpha-cholestane-3alpha,7alpha,12alpha,24,26-pentol. 2. M(D) studies suggest that this 5alpha-chimaerol is the 24(+), 25S enantiomer and that 5beta-chimaerol (chimaerol) from Chimaera monstrosa bile also has the 24(+), 25S configuration. These findings imply that bile alcohol biosynthesis in suckers and chimaeras includes stereospecific oxidation of cholesterol at C-26. 3. C. commersoni bile acids (present in minor amounts) probably consist largely of 3alpha,7alpha,12alpha-trihydroxy-5alpha-cholan-24-oic acid (allocholic acid). 4. 5alpha-Chimaerol sulphate and 5alpha-cyprinol sulphate are probably biochemically equivalent as bile salts, and can be considered as arising by parallel evolution.

SUBMITTER: Anderson IG

PROVIDER: S-EPMC1185402 | biostudies-other | 1970 Feb

REPOSITORIES: biostudies-other

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Project description:Enterohemorrhagic Escherichia coli (EHEC), including serotype O157:H7, cause severe food-borne illness. On route to the human colon, they encounter and resist, numerous anti-microbial ingestion stresses. We hypothesize that these stresses cue EHEC to alter virulence properties. This study investigated the impact of bile salts on virulence properties and examined the genetic basis of the phenotypes. Established assays were used to examine adhesion to human epithelial cells, motility, verotoxin (VT) production and antimicrobial resistance with/without bile salt stress. Bacteria treated for 90 minute in DMEM plus 0.15% (w/v) bile salt mix demonstrated significantly enhanced adhesion to epithelial cells and resistance to several antibiotics but did not increase motility or VT production. To determine the genetic basis of these phenotypes a microarray experiment was conducted. EHEC strain 86-24, in mid-log phase of growth, were grown in DMEM pH 7.4 (control), or DMEM plus bile salt mix (0.15% w/v), for 90 minutes, statically at 37˚C, 5% CO2 prior to harvesting RNA for the microarray study. Four biological replicates were produced for each treatment. Microarray and gene expression analysis (semi-quantitative RT-PCR and beta-galactosidase reporter assays) of bile salt-treated EHEC revealed significant up-regulation of genes for lipid A modification, fimbriae, an efflux pump, and a two-component regulatory system relative to the bacteria grown in DMEM alone. This work points to several mechanisms that EHEC employs to resist the stresses of the human small intestine, notably efflux, antimicrobial resistance, and outer membrane alterations. Bile salts enhanced the virulence-related properties of increased adhesion and resistance to antimicrobials but not VT production or motility. This research contributes to our understanding of how EHEC senses and responds to host environmental signals and the mechanisms this pathogen uses to successfully colonize and infect the human host.

Dataset Information

Comparative studies of bile salts. 5 alpha-Chimaerol, a new bile alcohol from the white sucker Catostomus commersoni Lacepede.

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