Meeting Abstract
10.4 Thursday, Jan. 3 Dietary phospholipids affect lipid storage in the gut and gonads of the sea urchin Lytechinus variegatus GIBBS, Victoria K.*; WATTS, Stephen A.; LAWRENCE, Addison L.; LAWRENCE, John M.; Univ. of Alabama at Birmingham; Univ. of Alabama at Birmingham; Texas A&M University System; Univ. of South Florida vkgibbs@uab.edu
Sea urchins are not only an ecologically important species, they also serve as important models for study of early embryonic development and ecotoxicology. Very little is known, however, about the nutritional requirements of the sea urchin, particularly when held long-term in the laboratory. In this study, the effect of supplemented dietary phospholipids (PL) was investigated to determine a potential requirement in juvenile L. variegatus. Sea urchins (average initial wet weight = 0.092 ± 0.001g, n = 16 per treatment) were fed semi-purified feeds containing 1, 2.5, 4, 5.2, 6.4, 7.6, or 8.8%, supplemented PL (as fed, exchanged with acid-washed diatomaceous earth) for 12 wk. Weight gain was dramatically reduced at the highest PL level; however, feed consumption and energy digestibilities were similar among the 1, 5.2, and 8.8% PL treatments. The mechanism of growth inhibition at high PL levels is not known. We further evaluated the lipid content of the primary storage tissues (gut and gonad) from individuals fed 1, 5.2, or 8.8% PL. Total (polar and nonpolar) lipid content of the gut and gonad was directly related to the PL level of the feed. Polar lipid in the gut and gonad differed only slightly among the three treatments. In contrast, individuals fed the 8.8% PL feed had significantly higher levels of nonpolar lipid in the gut than individuals in the 1 or 5.2% PL treatment (10.57, 4.62, and 5.35%, respectively). Nonpolar lipid level in the gonad was significantly higher for those individuals in both the 5.2 and 8.8% PL treatments. These data suggest that excess dietary PL is converted to nonpolar lipids (presumed triglycerides). Supported by Mississippi-Alabama Sea Grant and Texas Sea Grant.
