Wax ester biosynthesis by midwater marine animals

Lipid is a major energy reserve in many aquatic animals, and wax esters are the principal type of lipid present in most pelagic marine invertebrates and teleost fishes from deep water or near-surface cold waters. It has been suggested that these wax esters are biosynthesized by only a few organisms, and are then transferred along the food web to the fishes and marine mammals. We found that accessible mesopelagic myctophid (Lampanyctus ritteri, Stenobrachius leucopsarus and Triphoturus mexicanus) and gonostomatid (Cyclothone atraria and Gonodtoma gracile) fishes and crustaceans (Gaussia princeps, Calanus helgolandicus, Acanthephyra quadrispinosa and Sergestes prehensilis) biosynthesize wax esters from acetate, longchain alcohol or fatty acid precursors, in vivo or in vitro. In the latter experiments, organ tissues (hepatopancreas and gut) are more active than muscle, although, overall, fish muscle is probably a major site of wax ester biosynthesis in the species studied. Therefore, wax esters are not persistent dietary survivors in the food web of the oceanic midwaters; rather, most invertebrates and fishes in this environment make wax esters, modifying ingested fats to their own characteristic patterns.