Localization of peroxidized lipids in non-sedimentable microvesicles of senescing bean cotyledons
1993
Yao, K. | Paliyath, G. | Thompson, J.E.
Fluorescent peroxidized lipids are present in lipid extracts of microsomal membranes and cytosol from young and senescing bean (Phaseolus vulgaris) cotyledon tissue. In young tissue, the peroxidized membrane lipids are mainly phospholipids, whereas those in the cytosol are primarily free fatty acids. With advancing senescence, microsomal peroxidized lipids increase by 200% relative to membrane protein and by 50% on a per cotyledon basis, and the increase is mainly attributable to enhanced levels of peroxidized free fatty acids. Cytosolic peroxidized lipids expressed on a per cotyledon basis decline by 55% over the same period. Fractionation of the cytosol revealed that, for both young and senescing tissue, about 50% of the cytosolic fluorescent peroxidized lipids are associated with non-sedimentable microvesicles, which are formed from membranes and enriched in phospholipid catabolites. Moreover, the decline in cytosolic peroxidized lipids with advancing senescence correlates with progressive impairment of the formation of these non-sedimentable microvesicles.
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