The lipid composition of cytosolic particles isolated from senescing bean cotyledons

doi:10.1016/0031-9422(95)00111-J

Phytochemistry

Volume 39, Issue 6, August 1995, Pages 1335-1345

https://doi.org/10.1016/0031-9422(95)00111-J Get rights and content

Abstract

Non-sedimentable particles have been isolated from the cytosol of young two-day old and senescing seven-day-old bean cotyledons by ultrafiltration. The cytosolic particles have an average diameter of 240 nm and, when visualized in thin section by electron microscopy, appear osmiophilic and uniformly stained. Particles of similar size and morphology are also discernible in the cytoplasm of thin-sectioned cotyledon tissue. The cytosolic particles of both young and senescing tissue contain phospholipids with all of the fatty acids detectable in corresponding microsomal membrane phospholipids, and they also contain the same free sterols present in microsomal membranes. Free fatty acids and steryl/wax esters, phospholipid catabolites that are known to cause bilayer destabilization, are enriched in cytosolic particles relative to membranes by eight- to 23-fold and 41- to 213-fold for young and senescing cotyledon tissue, respectively. Thus phospholipid catabolite removal appears to be higher for the older membranes, but this notwithstanding, steryl/wax esters and free fatty acids still accumulate in microsomal membranes with advancing senescence. The data are consistent with the contention that blebbing of cytosolic particles from membranes is a means of removing phospholipid catabolites that would otherwise destabilize the bilayer, and suggest that the efficiency of catabolite removal is lower for senescing membranes.

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^∗: Present address: Department of Plant Science, University of British Columbia, Vancouver, British Columbia, Canada.

^†: Present address: Department of Biochemistry, Université de Montréal, Montréal, Québec, Canada.

^§: Present address: Department of Horticulture, Faculty of Agriculture, Hebrew University, Rehovot, Israel.

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Growth and metabolismThe lipid composition of cytosolic particles isolated from senescing bean cotyledons

Abstract

Phytochemistry

Biochim. Biophys. Acta

J. Biol. Chem.

Biochim. Biophys. Acta

Phytochemistry

Phytochemistry

Biochim. Biophys. Acta

Biochem. Biophys. Res. Commun.

FEBS Letters

Biochim. Biophys. Acta

Biochim. Biophys. Acta

Biochim. Biophys. Acta

J. Lipid Res.

J. Lipid Res.

Plant Physiol.

Plant Physiol.

Plant Physiol.

Plant Physiol.

Nature

Plant Physiol.

Growth and metabolism
The lipid composition of cytosolic particles isolated from senescing bean cotyledons