Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A1S6, Canada.
Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A1S6, Canada
J Exp Biol. 2019 Nov 6;222(Pt 21):jeb203455. doi: 10.1242/jeb.203455.
During migratory flight, desert locusts rely on fatty acids as their predominant source of energy. Lipids mobilized in the fat body are transported to the flight muscles and enter the muscle cells as free fatty acids. It has been postulated that muscle fatty acid binding protein (FABP) is needed for the efficient translocation of fatty acids through the aqueous cytosol towards mitochondrial β-oxidation. To assess whether FABP is required for this process, dsRNA was injected into freshly emerged adult males to knock down the expression of FABP. Three weeks after injection, FABP and its mRNA were undetectable in flight muscle, indicating efficient silencing of FABP expression. At rest, control and treated animals exhibited no morphological or behavioral differences. In tethered flight experiments, both control and treated insects were able to fly continually in the initial, carbohydrate-fueled phase of flight, and in both groups, lipids were mobilized and released into the hemolymph. Flight periods exceeding 30 min, however, when fatty acids become the main energy source, were rarely possible for FABP-depleted animals, while control insects continued to fly for more than 2 h. These results demonstrate that FABP is an essential element of skeletal muscle energy metabolism .
在迁徙飞行中，沙漠蝗虫主要依赖脂肪酸作为能量来源。脂肪体中动员的脂质被运输到飞行肌肉，并作为游离脂肪酸进入肌肉细胞。有人假设肌肉脂肪酸结合蛋白（FABP）对于脂肪酸通过水相细胞质向线粒体β-氧化的有效转运是必需的。为了评估 FABP 是否是这个过程所必需的，dsRNA 被注射到新羽化的成年雄性体内以敲低 FABP 的表达。注射后 3 周，飞行肌中无法检测到 FABP 及其 mRNA，表明 FABP 表达被有效地沉默。在休息时，对照和处理动物没有表现出形态或行为上的差异。在系留飞行实验中，对照和处理组的昆虫都能够在飞行的初始碳水化合物供能阶段持续飞行，并且在两组中，脂质都被动员并释放到血淋巴中。然而，对于 FABP 耗尽的动物来说，飞行时间超过 30 分钟，即脂肪酸成为主要能量来源的时间很少，而对照昆虫继续飞行超过 2 小时。这些结果表明，FABP 是骨骼肌能量代谢的重要组成部分。
