Varietal differences in the vitamin E content of corn

Combs, Stephanie B.; Combs, Gerald F.

doi:10.1021/jf00065a012

Cited by 19 publications

(5 citation statements)

References 4 publications

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“…Additionally, we found R-tocopherol as a major vitamin E derivative, while other derivatives were only present in trace amounts. This finding cannot be explained by the composition of the diet since corn meal contains, besides R-tocopherol, other derivatives thereof in large quantities (40). In mammals, a specific R-tocopherol transfer protein (TTP) contributes to enrichment of R-tocopherol in the body.…”

Section: Discussionmentioning

confidence: 99%

The Drosophila Class B Scavenger Receptor NinaD-I Is a Cell Surface Receptor Mediating Carotenoid Transport for Visual Chromophore Synthesis

et al. 2006

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The blind Drosophila mutant ninaD lacks the visual chromophore. Genetic evidence that the molecular basis is a defect in carotenoid uptake which causes vitamin A deficiency exists. The ninaD gene encodes a scavenger receptor that is significantly homologous in sequence with the mammalian scavenger receptors SR-BI (scavenger receptor class B type I) and CD36 (cluster determinant 36), yet NinaD has not been characterized in functional detail. Therefore, we established a Drosophila S2 cell culture system for biochemically characterizing the ninaD gene products. We show that the two splice variant isoforms encoded by ninaD exhibit different subcellular localizations. NinaD-I, the long protein variant, is localized at the plasma membrane, whereas the short variant, NinaD-II, is localized at intracellular membranes. Only NinaD-I could mediate the cellular uptake of carotenoids from micelles in this cell culture system. Carotenoid uptake was concentration-dependent and saturable. By in vivo analyses of different mutant and transgenic fly strains, we provide evidence of an essential role of NinaD-I in the absorption of dietary carotenoids to support visual chromophore synthesis. Moreover, our analyses suggest a role of NinaD-I in tocopherol metabolism. Even though Drosophila is a sterol auxotroph, we found no evidence of a contribution of NinaD-I to the uptake of these compounds. Together, our study establishes an evolutionarily conserved connection between class B scavenger receptors and the numerous functions of fat soluble vitamins in animal physiology.

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Section: Discussionmentioning

confidence: 99%

The Drosophila Class B Scavenger Receptor NinaD-I Is a Cell Surface Receptor Mediating Carotenoid Transport for Visual Chromophore Synthesis

et al. 2006

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“…Results are expressed as nanomoles of NADPH oxidized per minute per milligram of protein. Serum vitamin E levels were determined by reverse-phase high-performance liquid-liquid chromatography using a C18 column with detection by molecular fluorescence using a modification of the method of Combs and Combs (20). The method was standardized using all-rac-a-tocopherol and was ca-pable of detecting a-tocopherol levels down to 0.01 pg/mg of tissue.…”

Section: Materials and Methods Animals And Dietsmentioning

confidence: 99%

Effect of Selenium and Vitamin E Dietary Deficiencies on Chick Lymphoid Organ Development

Marsh

Combs

Whitacre

et al. 1986

Experimental Biology and Medicine

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Diets specifically deficient in selenium (Se) and/or vitamin E or adequate in both nutrients were fed to chicks from the time of hatching. Lymphoid organs (bursa, thymus, and in some instances, spleen) were collected from chicks 7-35 days of age. Growth of the chicks fed these diets was monitored over the experimental period as was lymphoid organ growth. The development of the primary lymphoid organs was further assessed by histological techniques and the organ contents of vitamin E (a-tocopherol) and Se were determined. Specific deficiencies of either Se or vitamin E were found to significantly impair bursal growth as did a combined deficiency. Thymic growth was impaired only by the combined deficiency diet. Severe histopathological changes in the bursa resulted from the combined deficiency and these were detectable by 10-14 days after hatching. These changes were characterized by a gradual degeneration of the epithelium and an accompanying depletion of lymphocytes. Similar changes, although slower to develop and less severe, were observed in the thymus as a result of the combined deficiency. When both serum and tissue levels of vitamin E and Se were monitored, it was observed that these were rapidly and independently depleted by the specific deficiency diets. These data suggest that the primary lymphoid organs are major targets of Se and vitamin E dietary deficiencies and provide a possible mechanism by which immune function may be impaired.

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“…Although a variation in total and individual tocopherol content from one sample of soybeans to another has been observed, there has not been an attempt to determine whether varietal differences exist or whether the observed variation is due to other factors. Varietal differences have been reported for corn (Combs and Combs, 1985) and winged beans (de Lumen and Fiad, 1982) recently.…”

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confidence: 93%