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Acetate and mevalonate labeling studies with developing Cuphea lutea seeds
Author(s) -
Singh Sheo S.,
Nee Thomas Y.,
Pollard Michael R.
Publication year - 1986
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02534436
Subject(s) - squalene , biochemistry , biosynthesis , sterol , fatty acid , chemistry , palmitic acid , mevalonic acid , lipidology , cholesterol , biology , enzyme
Cuphea seeds contain large amounts of medium chain (C 8 to C 14 ) fatty acids, mainly as triacylglycerols. The biosynthesis of these lipids was studied in vivo by incubating developing Cuphea lutea seeds with labeled acetate. Incorporation of label into triacylglycerols and into medium chain fatty acids occurred principally during the period of endogenous lipid deposition, but some label was encountered in these products even during seed dehydration. At this later stage palmitate and oleate were the dominant labeled fatty acids. During the period of rapid endogenous lipid deposition acyl lipids other than triacylglycerols were minor labeled components. The labeling patterns were consistent with the Kennedy pathway for triacylglycerol biosynthesis. The fatty acid composition of the acyl‐CoA pool was similar to the total lipid fatty acid composition, but the acyl‐ACP pool contained relatively more short chain acyl groups. Squalene was labeled from acetate throughout the period of seed development, but labeled sterols were not detected. Using [2‐ 14 C]mevalonic acid lactone as substrate, squalene was the principal labeled product. Small amounts of label were found in free sterols. However, in terms of mass, free sterol dominated over squalene. The possibility of two independent sites of isoprenoid biosynthesis in the developing embryo is discussed.