LIPID AND LIPOPROTEIN METABOLISM IN INSECTS

描述（改编自申请人的摘要）： 在昆虫的幼虫阶段，脂质储备积累并储存 脂肪体内的三酰甘油 这些储备用于成人 在飞行中被脂肪酸氧化。 此外，脂质是 在成年昆虫，如蚊子，必要的代谢储备， 而不是通过脂肪酸氧化来提供燃料。 尽管至关重要， 在成年昆虫中的脂质储备，相对而言， 它们在幼虫生活中积累的机制。 在许多情况下， 这涉及食物脂质的消化和脂肪酸的吸收 中肠，以及脂质从中肠通过中肠转运到脂肪体。 血淋巴脂蛋白，载脂蛋白。 昆虫也吸收其他食物脂质 在中肠中，例如，甾醇和类胡萝卜素，并将它们运输到 血淋巴通过脂转运蛋白。 这项建议涉及两个方面， 在幼虫期脂肪积累的过程 生活 (1)载脂蛋白生物合成途径的确定和 在幼虫脂肪体内组装。 在幼虫Manduca sexta中， 脂肪体作为含有载脂蛋白的新生脂蛋白颗粒 和磷脂，但没有核心或转运脂质。 直到最近， 不可能详细研究载脂蛋白的生物合成， 缺乏关于生物合成偶联的载脂蛋白的信息 产生新生的载脂蛋白。 然而，申请人的 一个实验室最近完成了3,305个氨基酸的cDNA测序， 酸性前体载脂蛋白，现在可以详细研究 载脂蛋白的生物合成和组装。 (2)测定 脂质在载脂蛋白和组织之间转移的机制， 尤其是脂肪体和中肠 Lipophorin作为一种可重复使用的 一种将脂质从一个组织转移到另一个组织的穿梭机， 进入组织。 这意味着脂质从 中肠与脂转运蛋白或脂转运蛋白与脂肪体的连接发生在界面处 在血淋巴和细胞质膜之间。 但 移交过程的细节尚不清楚。

DESCRIPTION (Adapted from the Applicant's Abstract): In holometabolous insects, lipid reserves are accumulated during the larval stage and stored as triacylglycerols in the fat body. These reserves are utilized in adults during flight fueled by fatty acid oxidation. In addition, lipids are essential metabolic reserves in adult insects, such as mosquitoes, that do not fuel flight by fatty acid oxidation. Despite the critical importance of lipid reserves in adult insects, relatively little is known about the mechanisms whereby they are accumulated during larval life. In many cases, this involves digestion of dietary lipids and absorption of fatty acids in the midgut, and transport of lipids from the midgut to the fat body via the hemolymph lipoprotein, lipophorin. Insects also absorb other dietary lipids in the midgut, e.g., sterols and carotenoids, and transport them in the hemolymph via lipophorin. This proposal is concerned with two aspects of the processes involved in the accumulation of lipid reserves during larval life. (1) Determination of the pathway for lipophorin biosynthesis and assembly in larval fat body. In larval Manduca sexta, lipophorin is made in the fat body as a nascent lipoprotein particle containing apolipoproteins and phospholipid, but no core or transported lipids. Until recently, it has not been possible to study the biosynthesis of lipophorin in detail due to lack of information about the apolipoproteins whose biosynthesis is coupled to production of the nascent lipophorin. However, the applicant's laboratory has recently completed sequencing the cDNA for the 3,305 amino acid precursor apolipoprotein and is now in a position to study in detail the biosynthesis and assembly of lipophorin. (2) Determination of the mechanism(s) whereby lipids are transferred between lipophorin and tissues, specifically the fat body and the midgut. Lipophorin serves as a reusable shuttle which moves lipids from one tissue to another without itself entering the tissue. This means that lipid transfer from the from the midgut to lipophorin or from lipophorin to fat body occurs at the interface between the hemolymph and the plasma membrane of the cell. However, the details of the transfer process are unknown.