The vitamin D system in iguanian lizards
نویسنده
چکیده
The apparent plasma concentration of vitamin D binding protein (DBP) in an iguanian lizard, Pogona barbata, and the affinity of this protein for 25-hydroxyvitamin D3 (25(OH)D3), 25-hydroxyvitamin D2 (25(OH)D2), and 1,25-dihydroxyvitamin D3 (1,25(OH)D3) was found to resemble more closely that of the domestic hen than that of the human. The characteristics of Pogona DBP, the pattern of vitamin D metabolites derived from injected radioactive vitamin D3 and the plasma concentrations of endogenous 25-hydroxyvitamin D (25(OH)D) in a range of iguanian lizards have been examined. The findings suggest that 25-hydroxyvitamin D (25(OH)D) is the major metabolite of vitamin D, and that it may represent the storage form of vitamin D in these species in the same way as in mammals. High concentrations of vitamin D within iguanian embryos and egg yolks suggest a role for this compound in embryogenesis in these species, and perhaps indicates that there is a mechanism for vitamin D delivery to eggs comparable to that found in the domestic chicken. © 1999 Elsevier Science Inc. All rights reserved.
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