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Journal of Lipid Research, Vol. 42, 225-234, February 2001
Copyright © 2001 by Lipid Research, Inc.
Diacylglycerol transport in the insect fat body: evidence of involvement of lipid droplets and the cytosolic fraction
Estela L. Arreseb,
Justin L. Gazarda,
Matthew T. Flowersa,
Jose L. Soulagesb, and
Michael A. Wellsa
a Department of Biochemistry and Center for Insect Science, University of Arizona, Tucson, AZ 85721
b Department of Biochemistry and Molecular Biology, 246 Noble Research Center, Oklahoma State University, Stillwater, OK 74078
Correspondence to:
Estela L. Arrese, To whom correspondence should be addressed., estela{at}biochem.okstate.edu (E-mail)
In this report we show the existence of a distinct pool of fat body diacylglycerol (DG) that can be distinguished from the bulk DG. This is a dynamic pool of DG that uses FA entering the fat body from the hemolymph, whereas the bulk DG uses the fatty acids stored in the fat body fat droplets. Using a dual labeling technique, it was possible to compare the effect of hormone-stimulated DG synthesis and secretion on the distribution of radiolabeled FA among the lipids of the dynamic pool (short-term radiolabeling), with the hormonal effect on the total complement of fat body lipids (long-term radiolabeling). We observed that, whereas DG represents 2% to 3% of the fat body lipid mass, about 20% of the short-term radiolabeled lipids are represented by DG. Stimulation of lipolysis produces a fast decrease in the fraction of short-term radiolabeled DG, whereas there is an increase in the mass of fat body DG. The subcellular distribution of bulk DG showed that its majority (62%) was in the fat cake whereas only 2.9% was in the cytosol.
On lipolysis stimulation, the largest changes in specific activities of newly synthesized DG were detected in the cytosol and the fat cake, suggesting that newly synthesized DG localized in the lipid droplets and the cytosol is preferentially mobilized. Arrese, E. L., J. L. Gazard, M. T. Flowers, J. L. Soulages, and M. A. Wells. Diacylglycerol transport in the insect fat body: evidence of involvement of lipid droplets and the cytosolic fraction. J. Lipid Res. 2001. 42: 225;234.
Supplementary key words:
AKH, Manduca sexta, lipolysis , lipid mobilization

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Copyright © 2001 by the American Society for Biochemistry and Molecular Biology.
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