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Adaptive regulation of membrane lipids and fluidity during thermal acclimation in Tetrahymena.

Nozawa Y - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2011)

Bottom Line: Exposure of Tetrahymena cells to the cold temperature induces marked alterations in the lipid composition and the physical properties (fluidity) of various membranes.The increase in fatty acid unsaturation of membrane phospholipids is required to preserve the proper fluidity.In this homeoviscous adaptive response, acyl-CoA desaturase plays a pivotal role and its activity is regulated by induction of the enzyme via transcriptional activation.

View Article: PubMed Central - PubMed

Affiliation: Department of Health and Food Sciences, Tokai Gakuin University, Kakamigahara, Japan. ynozawa@giib.or.jp

ABSTRACT
The free-living eukaryotic protozoan Tetrahymena is a potentially useful model for the thermoadaptive membrane regulation because of easy growth in the axenic culture, systematic isolation of subcellular organelles, and quick response to temperature stress. Exposure of Tetrahymena cells to the cold temperature induces marked alterations in the lipid composition and the physical properties (fluidity) of various membranes. The increase in fatty acid unsaturation of membrane phospholipids is required to preserve the proper fluidity. In this homeoviscous adaptive response, acyl-CoA desaturase plays a pivotal role and its activity is regulated by induction of the enzyme via transcriptional activation.

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The order parameter of 5-nitroxide stearate label in various membranes of T. pyriformis as a function of the reciprocal of the absolute temperature. Data from Nozawa et al. (1974).10)
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fig02: The order parameter of 5-nitroxide stearate label in various membranes of T. pyriformis as a function of the reciprocal of the absolute temperature. Data from Nozawa et al. (1974).10)

Mentions: Fluidity-related parameters of isolated membrane fractions have been examined by several physico-chemical techniques, such as electron spin resonance (ESR), X-ray diffraction, fluorescence depolarization and 31PNMR. The fact that general agreement is found using these basically different physical-chemical tools inspires a high degree of confidence that each membrane type within a eukaryotic cell possesses very specific physical properties determined largely by its lipid composition. ESR study with the use of the probe 5-nitrostearate demonstrated that the membranes are more fluid in the order, microsomes > pellicles > cilia10) (Fig. 2). The localization of certain lipids is striking in particular Tetrahymena membrane fractions, which perhaps reflects a diversity in the physical state of the membranes. Taking into consideration that the content of tetrahymanol increases in the order, cilia > pellicles > microsomes, one would expect that this specific sterol-like lipid might be involved in stabilizing membrane fluidity, as observed in cholesterol of mammalian cells.


Adaptive regulation of membrane lipids and fluidity during thermal acclimation in Tetrahymena.

Nozawa Y - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2011)

The order parameter of 5-nitroxide stearate label in various membranes of T. pyriformis as a function of the reciprocal of the absolute temperature. Data from Nozawa et al. (1974).10)
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3313689&req=5

fig02: The order parameter of 5-nitroxide stearate label in various membranes of T. pyriformis as a function of the reciprocal of the absolute temperature. Data from Nozawa et al. (1974).10)
Mentions: Fluidity-related parameters of isolated membrane fractions have been examined by several physico-chemical techniques, such as electron spin resonance (ESR), X-ray diffraction, fluorescence depolarization and 31PNMR. The fact that general agreement is found using these basically different physical-chemical tools inspires a high degree of confidence that each membrane type within a eukaryotic cell possesses very specific physical properties determined largely by its lipid composition. ESR study with the use of the probe 5-nitrostearate demonstrated that the membranes are more fluid in the order, microsomes > pellicles > cilia10) (Fig. 2). The localization of certain lipids is striking in particular Tetrahymena membrane fractions, which perhaps reflects a diversity in the physical state of the membranes. Taking into consideration that the content of tetrahymanol increases in the order, cilia > pellicles > microsomes, one would expect that this specific sterol-like lipid might be involved in stabilizing membrane fluidity, as observed in cholesterol of mammalian cells.

Bottom Line: Exposure of Tetrahymena cells to the cold temperature induces marked alterations in the lipid composition and the physical properties (fluidity) of various membranes.The increase in fatty acid unsaturation of membrane phospholipids is required to preserve the proper fluidity.In this homeoviscous adaptive response, acyl-CoA desaturase plays a pivotal role and its activity is regulated by induction of the enzyme via transcriptional activation.

View Article: PubMed Central - PubMed

Affiliation: Department of Health and Food Sciences, Tokai Gakuin University, Kakamigahara, Japan. ynozawa@giib.or.jp

ABSTRACT
The free-living eukaryotic protozoan Tetrahymena is a potentially useful model for the thermoadaptive membrane regulation because of easy growth in the axenic culture, systematic isolation of subcellular organelles, and quick response to temperature stress. Exposure of Tetrahymena cells to the cold temperature induces marked alterations in the lipid composition and the physical properties (fluidity) of various membranes. The increase in fatty acid unsaturation of membrane phospholipids is required to preserve the proper fluidity. In this homeoviscous adaptive response, acyl-CoA desaturase plays a pivotal role and its activity is regulated by induction of the enzyme via transcriptional activation.

Show MeSH
Related in: MedlinePlus