C Albendea | PubMed Health

PubMed2005

Effects of trace elements on membrane fluidity.

According to the Fluid Mosaic Model, a biological membrane is a two-dimensional fluid of oriented proteins and lipids. The lipid bilayer is the basic structure of all cell and organelle membranes. Cell membranes are dynamic, fluid structures, and most of their molecules are able to move in the plane of the membrane. Fluidity is the quality of ease of movement and represents the reciprocal value of membrane viscosity. Fluid properties of biological membranes are essential for numerous cell functions. Even slight changes in membrane fluidity may cause aberrant function and pathological processes. Several evidences suggest that trace elements, e.g., iron, copper, zinc, selenium, chromium, cadmium, mercury and lead may influence membrane fluidity. The interaction of heavy metals with cellular membranes may contribute to explain, at least partially, the toxicity associated with these metals.

Cell Membrane↗

PubMed2000

Phenotypic and genetic characterization of Lactococcus garvieae isolated in Spain from lactococcosis outbreaks and comparison with isolates of other countries and sources.

The phenotypic and genetic analysis results for 84 isolates of Lactococcus garvieae (including 62 strains from trout with lactococcosis from four different countries, 7 strains from cows and water buffalos with subclinical mastitis, 3 from water, and 10 from human clinical samples) are presented. There was great phenotypic heterogeneity (13 different biotypes) based on the acidification of saccharose, tagatose, mannitol, and cyclodextrin and the presence of the enzymes pyroglutamic acid arylamidase and N-acetyl-beta-glucosaminidase. L. garvieae also exhibited high genetic diversity by pulsed-field gel electrophoresis (PFGE), with 19 different pulsotypes among the isolates of L. garvieae studied. Only epidemiologically related strains, like the Spanish and Italian fish isolates and the cow and water buffalo isolates, displayed a close genetic relationship by PFGE, while the strains isolated from sporadic clinical cases, like the human isolates, were genetically unrelated. Overall, a general correlation between phenotypic and genetic data was observed. Epidemiological analysis of biotype and PFGE results indicated that the trout lactococcosis outbreaks in Spain and Portugal and those in France and Italy were produced by genetically unrelated clones. In Spain, two different clones were detected; the outbreaks diagnosed from 1995 onward were produced by a clone (biotype 2, pulsotype A1) which, although genetically related, was different from the one that was responsible for the outbreaks studied between 1991 and 1994 (biotype 1, pulsotype B). The Portuguese isolate had a biochemical profile identical to that of the Spanish strain isolated from 1995 onward and is also genetically closely related to this strain (pulsotype A2). There was a close relationship between the two pulsotypes (E and F) found in the Italian isolates. The French isolate (biotype 3, pulsotype D) was not genetically related to any other L. garvieae fish isolate. These results suggest the existence of diverse infection sources for the different lactococcosis outbreaks.

Animals↗