Carotenoid transport in the plasma of the scarlet ibis ( Eudocimus ruber)

Abstract

1. 1. A study was made of the lipoprotein composition of blood plasma from the scarlet ibis ( Eudocimus ruber), white ibis and a pink hybrid. Donor animals were obtained either from the delta of the Amazon River or from the National Zoo, Washington, D.C. 2. 2. It was found that the carotenoid composition of the plasma of the captive scarlet ibis differed from that of the wild bird. 3. 3. The carotenoid pigments which are characteristic for scarlet ibis were principally associated with the high-density lipoprotein fractions. Pigment half-life was of the order of 80–100 hr and consistent with the metabolism of high-density lipoproteins (HDL). 4. 4. Further fractionation of the HDL by disc electrophoresis indicated the presence of a component which appears to be a carotenoid carrier protein. Substantial amounts of this protein were present in the scarlet ibis whereas only traces could be detected in the white ibis.