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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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General feature of ultrathin-sectioned T. pyriformis. PM, plasma membrane; OAM, outer alveolar membrane; IAM, inner alveolar membrane; CM, ciliary membrane; M, mitochondria; KS, kinetosome; MT, microtubule; AS, alveolar space; FV, food vacuole. From Nozawa (1975).3)
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fig01: General feature of ultrathin-sectioned T. pyriformis. PM, plasma membrane; OAM, outer alveolar membrane; IAM, inner alveolar membrane; CM, ciliary membrane; M, mitochondria; KS, kinetosome; MT, microtubule; AS, alveolar space; FV, food vacuole. From Nozawa (1975).3)

Mentions: The ciliate protozoan Tetrahymena, which is approximately 60 µm in length and 20 µm in width, grows well axenically in lipid-free media and it can be therefore considered a closed system with respect to the economy of its membrane components. All lipids and proteins are synthesized de novo within the cell, primarily in one compartment, and are then disseminated to various structurally and functionally different membranes for utilization. A wealth of structural and biochemical details reveals Tetrahymena to be a typical cell.2)Tetrahymena cell contains the subcellular organelles typically found in eukaryotic cells, such as mitochondria, lysosomes, endoplasmic reticulum, peroxisomes, but no typical Golgi apparatus. The highly specialized surface structures are less typical (Fig. 1). Underlying the plasma membrane is an extensive anastomosing system of alveolar sacs of unknown function. The outer alveolar membrane is closely apposed to the plasma membrane and actually joined to it by cross bridges. This entire system of cortical membranes is referred to as the pellicle. Another membrane specialization of the cell surface is the oral apparatus, which is a permanently fixed structure designed for the endocytosis. Being a free-living unicellular organism, it furnishes the key advantages of bacteria with respect to rapid growth and easy manipulation. Thus, Tetrahymena has been chosen as an appropriate model for the use in studying the structure and function of biological membranes, particularly membrane biogenesis and membrane adaptation (lipids and fluidy) to environmental stresses.3–6)


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

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

General feature of ultrathin-sectioned T. pyriformis. PM, plasma membrane; OAM, outer alveolar membrane; IAM, inner alveolar membrane; CM, ciliary membrane; M, mitochondria; KS, kinetosome; MT, microtubule; AS, alveolar space; FV, food vacuole. From Nozawa (1975).3)
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig01: General feature of ultrathin-sectioned T. pyriformis. PM, plasma membrane; OAM, outer alveolar membrane; IAM, inner alveolar membrane; CM, ciliary membrane; M, mitochondria; KS, kinetosome; MT, microtubule; AS, alveolar space; FV, food vacuole. From Nozawa (1975).3)
Mentions: The ciliate protozoan Tetrahymena, which is approximately 60 µm in length and 20 µm in width, grows well axenically in lipid-free media and it can be therefore considered a closed system with respect to the economy of its membrane components. All lipids and proteins are synthesized de novo within the cell, primarily in one compartment, and are then disseminated to various structurally and functionally different membranes for utilization. A wealth of structural and biochemical details reveals Tetrahymena to be a typical cell.2)Tetrahymena cell contains the subcellular organelles typically found in eukaryotic cells, such as mitochondria, lysosomes, endoplasmic reticulum, peroxisomes, but no typical Golgi apparatus. The highly specialized surface structures are less typical (Fig. 1). Underlying the plasma membrane is an extensive anastomosing system of alveolar sacs of unknown function. The outer alveolar membrane is closely apposed to the plasma membrane and actually joined to it by cross bridges. This entire system of cortical membranes is referred to as the pellicle. Another membrane specialization of the cell surface is the oral apparatus, which is a permanently fixed structure designed for the endocytosis. Being a free-living unicellular organism, it furnishes the key advantages of bacteria with respect to rapid growth and easy manipulation. Thus, Tetrahymena has been chosen as an appropriate model for the use in studying the structure and function of biological membranes, particularly membrane biogenesis and membrane adaptation (lipids and fluidy) to environmental stresses.3–6)

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