This article is available online at http://www.jlr.org have used zebrafi sh to characterize the molecular consequences of vitamin E defi ciency because zebrafi sh require dietary ␣ -tocopherol, especially during embryonic development ( 2 ). Zebrafi sh also express the ␣ -tocopherol transfer protein ( ␣ -TTP), which facilitates hepatic ␣ -tocopherol secretion into the circulation in humans ( 3 ), and likely facilitates ␣ -tocopherol delivery from the yolk to the developing zebrafi sh embryo ( 4 ). Importantly, when the ␣ -TTP was knocked down in zebrafi sh embryos by 12-15 h postfertilization, the embryonic brain and eyes failed to form appropriately ( 4 ), indicating that ␣ -tocopherol is necessary for nervous system development. Further, during embryonic growth over 72 h both DHA (22:6) and arachidonic acid (AA) (20:4) decreased at faster rates in vitamin E-defi cient (E Ϫ ) compared with vitamin E-suffi cient (E+) zebrafi sh embryos ( 5 ). Moreover, adequate dietary ascorbic acid was necessary to prevent accelerated ␣ -tocopherol defi ciency and tissue damage ( 5 ).We hypothesized that the devastating effects of severe ␣ -tocopherol defi ciency in zebrafi sh embryos ( 4 ) are a result of depletion and alteration of critical brain lipids. Hypothetically, the brain, which is highly enriched in DHA yet cannot synthesize DHA to meet its needs ( 6 ), is highly susceptible to lipid peroxidation in the ␣ -tocopheroldefi cient state. It has been recognized for decades in humans that vitamin E defi ciency causes a progressive spinocerebellar ataxia ( 7 ). Moreover, Ulatowski et al. ( 8 ) have shown that vitamin E is necessary for preservation of Abstract We hypothesized that brains from vitamin E-defi cient (E ؊ ) zebrafi sh ( Danio rerio ) would undergo increased lipid peroxidation because they contain highly polyunsaturated fatty acids, thus susceptible lipids could be identifi ed. Brains from zebrafi sh fed for 9 months defi ned diets without (E ؊ ) or with (E+) added vitamin E (500 mg RRR -␣ -tocopheryl acetate per kilogram diet) were studied. Using an untargeted approach, 1-hexadecanoyl-2-docosahexaenoyl-sn -glycero-3-phosphocholine [DHA-PC 38:6, PC 16:0/22:6]was the lipid that showed the most signifi cant and greatest fold-differences between groups. DHA-PC concentrations were approximately 1/3 lower in E ؊ (4.3 ± 0.6 mg/g) compared with E+ brains (6.5 ± 0.9 mg/g, mean ± SEM, n = 10 per group, P = 0.04). Using lipidomics, 155 lipids in brain extracts were identifi ed. Only four phospholipids (PLs) were different ( P < 0.05) between groups; they were lower in E ؊ brains and contained DHA with DHA-PC 38:6 at the highest abundances. Moreover, hydroxy-DHA-PC 38:6 was increased in E ؊ brains ( P = 0.0341) supporting the hypothesis of DHA peroxidation. More striking was the depletion in E ؊ brains of nearly 60% of 19 different lysophospholipids (lysoPLs) (combined P = 0.0003), which are critical for membrane PL remodeling. Thus, E ؊ brains contained fewer DHA-PLs, more hydroxy-DHA-PCs, and fewer lysoPLs, suggesting t...