Expression of ApoltpdsRNA.Scer\UAS.II in the fat body under the control of Scer\GAL4Adh.PF (initiated by heat shock during the early larval stages) results in dramatic enlargement of the neutral fat droplets in the larval posterior midgut.
Expression of ApoltpdsRNA.Scer\UAS.II under the control of Scer\GAL4Rfabg.PB reduces the larval hemolymph levels of medium-chain diacylglycerol (DAG) (DAG26 and DAG28) and sterols by about 70%. In contrast, levels of PE, the major polar Lpp lipid, are not changed. The amounts of several minor lipid classes (phosphatidylcholine (PC), triacylglycerol (TAG), sphingolipids) increase slightly.
In larval guts expressing ApoltpdsRNA.Scer\UAS.II under the control of Scer\GAL4Adh.PF the levels of medium-chain diacylglycerol (DAG) increase 5-8 fold with respect to polar lipids. Long chain DAG increases moderately, and contributes less to the total elevation in gut DAG. Loss of Apoltp also leads to a strong increase in triacylglycerol (TAG) in the gut, with medium-chain TAG the most strongly elevated. An increase in TAG and DAG is seen in both lipid-fed and lipid-starved animals.
The fat bodies of larvae expressing ApoltpdsRNA.Scer\UAS.II under the control of Scer\GAL4Adh.PF contain much less sterol than those of wild type flies. Fat bodies also contain much less medium-chain diacylglycerol (DAG). Fat body triacylglycerol (TAG) storage is reduced by 30%, but the morphology of neutral lipid droplets is not obviously altered.
Expression of ApoltpdsRNA.Scer\UAS.II under the control of Scer\GAL4Adh.PF specifically depletes levels of medium chain diacylglycerol (DAG) in the wing disc. Long-chain DAG levels are unaffected. Total triacylglycerol (TAG) levels are reduced by 40% and the size and number of neutral lipid droplets are modestly reduced. The reduction in medium-chain TAG levels is more severe than the reduction in long-chain species. Long-chain PE levels are also unaffected.
Expression of ApoltpdsRNA.Scer\UAS.II in the fat body under the control of Scer\GAL4Adh.PF has no effect on neutral lipid levels in the larval brain.