Dietary trans–fatty acids alter adipocyte plasma membrane fatty acid composition and insulin sensitivity in rats

Sub-lethal high-pressure homogenization treatments applied to Lactobacillus paracasei A13 demonstrated to be a useful strategy to enhance technological and functional properties without detrimental effects on the viability of this strain. Modification of membrane fatty acid composition is reported to be the main regulatory mechanisms adopted by probiotic lactobacilli to counteract high-pressure stress. This work is aimed to clarify and understand the relationship between the modification of membrane fatty acid composition and the expression of genes involved in fatty acid biosynthesis in Lactobacillus paracasei A13, before and after the application of different sub-lethal hyperbaric treatments. Our results showed that Lactobacillus paracasei A13 activated a series of reactions aimed to control and stabilize membrane fluidity in response to high-pressure homogenization treatments. In fact, the production of cyclic fatty acids was counterbalanced by the unsaturation and elongation of fatty acids. The gene expression data indicate an up-regulation of the genes accA, accC, fabD, fabH and fabZ after high-pressure homogenization treatment at 150 and 200 MPa, and of fabK and fabZ after a treatment at 200 MPa suggesting this regulation of the genes involved in fatty acids biosynthesis as an immediate response mechanism adopted by Lactobacillus paracasei A13 to high-pressure homogenization treatments to balance the membrane fluidity. Although further studies should be performed to clarify the modulation of phospholipids and glycoproteins biosynthesis since they play a crucial role in the functional properties of the probiotic strains, this study represents an important step towards understanding the response mechanisms of Lactobacillus paracasei A13 to sub-lethal high-pressure homogenization treatments.

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Influence of altered plasma membrane fatty acid composition on cesium transport characteristics and toxicity inSaccharomyces cerevisiae

Canadian Journal of Microbiology ◽

10.1139/m97-137 ◽

1997 ◽

Vol 43 (10) ◽

pp. 954-962 ◽

Cited By ~ 10

Author(s):

Michael J. Hoptroff ◽

Simon V. Avery ◽

Simon Thomas

Keyword(s):

Fatty Acid Composition ◽

Plasma Membrane ◽

Fatty Acid ◽

Acid Composition ◽

Protein Interactions ◽

Kinetic Studies ◽

Monovalent Cation ◽

Membrane Fatty Acid ◽

Membrane Fatty Acid Composition ◽

Prolonged Incubation

The influence of altered plasma membrane fatty acid composition on cesium uptake and toxicity was investigated in Saccharomyces cerevisiae. Detailed kinetic studies revealed that both the Vmaxand Kmvalues for Cs+transport increased (by approximately twofold in the latter case) when S. cerevisiae was grown in medium supplemented with the polyunsaturated fatty acid linoleate. In addition, Cs+uptake by linoleate-enriched cells was considerably less sensitive to the competitive effects of other monovalent cations (K+, Rb+, and NH4+) than that by unsupplemented cells. Stimulation of Cs+uptake in the presence of certain K+and Rb+concentrations was only evident in linoleate-enriched S. cerevisiae. At 100 mM CsCl, the initial rate of Cs+uptake was greater in linoleate-supplemented cells than in unsupplemented cells and this was reflected in a more rapid displacement of cellular K+. However, little difference in net Cs+accumulation between linoleate-supplemented and unsupplemented cells was evident during prolonged incubation in buffer or during growth. Thus, Cs+toxicity was similar in linoleate-supplemented and unsupplemented cells. The results were consistent with the Cs+(K+) transport mechanism adopting an altered conformational state in linoleate-enriched S. cerevisiae.Key words: monovalent cation transport, plasma membrane fatty acid composition, lipid–protein interactions, metal–microbe interactions, cation competition.

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