Biosynthesis of mandibular acids in honey bees (Apis mellifera): De novo synthesis, route of fatty acid hydroxylation and caste selective beta-oxidation
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| Authors: | Plettner, E; Slessor, KN; Winston, ML |
| Year: | 1998 |
| Journal: | Insect Biochem. Mol. Biol. 28: 31-42 Article Link (DOI) |
| Title: | Biosynthesis of mandibular acids in honey bees (Apis mellifera): De novo synthesis, route of fatty acid hydroxylation and caste selective beta-oxidation |
| Abstract: | Fatty acids functionalized at the last (omega) and penultimate (omega-1) position, found in the mandibular glands of worker and queen honey bees (Apis mellifera L.), have important functions in the colony and are caste specific. Queens have predominantly 10-carbon omega-1-functionalized acids and workers have 10-carbon omega-functionalized acids. In previous work we have shown that the mandibular acids are synthesized from octadecanoic acid in three steps: (1) hydroxylation at the omega and omega-1 position; (2) beta-oxidation of the 18-carbon hydroxy acids to the 8 and 10-carbon length; and (3) oxidation of the omega- and omega-1-hydroxy groups to give diacids and 9-keto-2(E)-decenoic acid, respectively. The last two steps are caste selective, In this work, we studied the biosynthesis of mandibular acids from acetate, distinguished among two possible routes of hydroxylation and studied caste differences in hydroxy acid chain shortening. Workers glands biosynthesize mandibular acids from acetate and, therefore, do not depend on an external source of octadecanoic acid. Hydroxylation at the omega position proceeds with retention of label at the omega-1 position. Hydroxylation at the omega-1 position proceeds with retention of label at the omega position and does not involve a terminal double bond. Finally, hydroxy acid chain shortening differs in queens and workers in two respects: (1) the inhibition pattern in the presence of 2-fluorooctadecanoic acid; and (2) reversibility. Chain shortening is inhibited by 2-fluorooctadecanoic acid to a greater extent in workers than in queens, Furthermore, workers are able to elongate hydroxy acids to the next higher 2-carbon homologue and are able to reduce hydroxy-2(E)-decenoic acids to the corresponding hydroxydecanoic acids. These transformations were not detected in queens. (C) 1998 Elsevier Science Ltd. All rights reserved. |
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