LIPID AND LIPOPROTEIN METABOLISM IN INSECTS

描述(改编自申请人的摘要)：全变态 昆虫，脂肪储备在幼虫阶段积累并储存 脂肪体内的三酰甘油。这些储备在成年人身上使用 在飞行过程中由脂肪酸氧化提供燃料。此外，脂类是 成虫体内的基本代谢储备，如蚊子 而不是通过脂肪酸氧化来为飞行提供燃料。尽管关键的重要性在于 成虫体内的脂肪储备，相对较少了解 它们在幼虫生活中积累的机制。在许多情况下， 这包括食物中脂肪的消化和脂肪酸的吸收。 中肠，以及脂肪从中肠到脂肪体的运输 血淋巴脂蛋白、脂蛋白。昆虫还会吸收其他食物中的脂肪 在中肠中，如类固醇和类胡萝卜素，并将它们在 血淋巴通过脂蛋白。这项提案涉及以下两个方面 幼虫体内脂肪储备积累的过程 生活。(1)脂蛋白生物合成途径的测定和 在幼虫脂肪体中组装。在六分圆线虫幼虫中，脂蛋白是由 脂肪体作为含有载脂蛋白的新生脂蛋白颗粒 和磷脂，但没有核心或运输类脂。直到最近，它一直在 无法详细研究脂蛋白的生物合成，原因是 缺乏关于生物合成偶联的载脂蛋白的信息 新生的脂蛋白的生产。然而，申请人的 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，现在可以进行详细研究 脂蛋白的生物合成和组装。(2)确定 脂质在脂蛋白和组织之间转移的机制(S)， 特别是肥胖的身体和中肠。脂蛋白是一种可重复使用的 将脂肪从一个组织转移到另一个组织而不需要自身的穿梭 进入组织。这意味着脂质从体内转移到 中肠到脂蛋白或从脂蛋白到脂肪体发生在界面上。 在血淋巴和细胞质膜之间。然而， 转移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.