TY - JOUR
T1 - The basis for colorless hemolymph and cocoons in the Y-gene recessive Bombyx mori mutants
T2 - A defect in the cellular uptake of carotenoids
AU - Tsuchida, Kozo
AU - Katagiri, Chihiro
AU - Tanaka, Yoshiro
AU - Tabunoki, Hiroko
AU - Sato, Ryoichi
AU - Maekawa, Hideaki
AU - Takada, Naoko
AU - Banno, Yutaka
AU - Fujii, Hiroshi
AU - Wells, Michael A.
AU - Jouni, Zeina E.
PY - 2004/10/1
Y1 - 2004/10/1
N2 - Bombyx mori is an excellent model for the study of carotenoid-binding proteins (CBP). In previous papers, we identified and molecularly characterized a CBP from the Y-gene dominant mutants. In the present study, we attempted to correlate and establish lipid metabolism and distribution in these mutants. When [ 3H]-triolein was fed to the mutants, typical patterns of uptake of labeled fatty acids from midgut to hemolymph and subsequent delivery to fat body and silk glands were obtained in all mutants. Further analysis of lipid and carotenoid profiles revealed that the yellow coloration in the hemolymph associated with lipophorin is not attributed to a difference in lipophorin concentrations among the mutants, nor to its lipid composition, but rather to its carotenoid content. Lipophorin of the Y+ I mutant exhibited the highest concentration of total carotenoids of 55.8 μg/mg lipophorin compared to 3.1 μg/mg in the + Y+ I mutant, 1.2 μg/mg in the YI mutant and 0.5 μg/mg in the + YI mutant. Characteristic retention time in HPLC of the different classes of carotenoids of lipophorin identified the presence of lutein as the major chromophore (62-77%), followed by β-carotenes (22-38%). Although lutein and β-carotene content of mutants' lipophorin differed significantly, the ratio of lutein to β-carotene of 3:1 was not different among mutants. Similarly, lipid compositions of mutant silk glands were not significantly different, but carotenoid contents were. The significantly high concentration of lutein in the Y+ I mutant silk gland represented more than 160-fold increase compared to + Y+ I mutant (p<0.001). In this report, we conclude that lipid metabolism in the mutants is not defected and that the molecular basis for colorless hemolymph and cocoons is a defect in the cellular uptake of lutein associated with the Y-gene recessive mutants.
AB - Bombyx mori is an excellent model for the study of carotenoid-binding proteins (CBP). In previous papers, we identified and molecularly characterized a CBP from the Y-gene dominant mutants. In the present study, we attempted to correlate and establish lipid metabolism and distribution in these mutants. When [ 3H]-triolein was fed to the mutants, typical patterns of uptake of labeled fatty acids from midgut to hemolymph and subsequent delivery to fat body and silk glands were obtained in all mutants. Further analysis of lipid and carotenoid profiles revealed that the yellow coloration in the hemolymph associated with lipophorin is not attributed to a difference in lipophorin concentrations among the mutants, nor to its lipid composition, but rather to its carotenoid content. Lipophorin of the Y+ I mutant exhibited the highest concentration of total carotenoids of 55.8 μg/mg lipophorin compared to 3.1 μg/mg in the + Y+ I mutant, 1.2 μg/mg in the YI mutant and 0.5 μg/mg in the + YI mutant. Characteristic retention time in HPLC of the different classes of carotenoids of lipophorin identified the presence of lutein as the major chromophore (62-77%), followed by β-carotenes (22-38%). Although lutein and β-carotene content of mutants' lipophorin differed significantly, the ratio of lutein to β-carotene of 3:1 was not different among mutants. Similarly, lipid compositions of mutant silk glands were not significantly different, but carotenoid contents were. The significantly high concentration of lutein in the Y+ I mutant silk gland represented more than 160-fold increase compared to + Y+ I mutant (p<0.001). In this report, we conclude that lipid metabolism in the mutants is not defected and that the molecular basis for colorless hemolymph and cocoons is a defect in the cellular uptake of lutein associated with the Y-gene recessive mutants.
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U2 - 10.1016/j.jinsphys.2004.08.001
DO - 10.1016/j.jinsphys.2004.08.001
M3 - Article
C2 - 15518665
AN - SCOPUS:7244259056
VL - 50
SP - 975
EP - 983
JO - Journal of Insect Physiology
JF - Journal of Insect Physiology
SN - 0022-1910
IS - 10
ER -