Fruttero Leonardo L, Leyria Jimena, Canavoso Lilián E
Instituto do Cerebro (InsCer). Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, CP 5000, Argentina.
Results Probl Cell Differ. 2017;63:403-434. doi: 10.1007/978-3-319-60855-6_18.
In insect physiology, the mechanisms involved in the buildup and regulation of yolk proteins in developing oocytes have been thoroughly researched during the last three decades. Comparatively, the study of lipid metabolism in oocytes had received less attention. The importance of this issue lies in the fact that lipids make up to 40% of the dry weight of an insect egg, being the most important supply of energy for the developing embryo. Since the oocyte has a very limited capacity to synthesize lipids de novo, most of the lipids in the mature eggs arise from the circulation. The main lipid carriers in the insect circulatory system are the lipoproteins lipophorin and vitellogenin. In some species, the endocytosis of lipophorin and vitellogenin may account for about 10% of the lipids present in mature eggs. Thus, most of the lipids are transferred by a lipophorin-mediated pathway, in which the lipoprotein unloads its lipid cargo at the surface of oocytes without internalization. This chapter recapitulates the current status on lipid storage and its utilization in insect oocytes and discusses the participation of key factors including lipoproteins, transfer proteins, lipolytic enzymes, and dynamic organelles such as lipid droplets. The new findings in the field of lipophorin receptors are presented in the context of lipid accumulation during egg maturation, and the roles of lipids beyond energy source are summarized from the perspective of oogenesis and embryogenesis. Finally, prospective and fruitful areas of future research are suggested.
在昆虫生理学领域，过去三十年来，对发育中卵母细胞内卵黄蛋白的积累和调节机制已进行了深入研究。相比之下，卵母细胞脂质代谢的研究受到的关注较少。这个问题的重要性在于，脂质占昆虫卵干重的40%，是发育中胚胎最重要的能量来源。由于卵母细胞从头合成脂质的能力非常有限，成熟卵中的大部分脂质来自循环系统。昆虫循环系统中的主要脂质载体是脂蛋白脂转运蛋白和卵黄原蛋白。在某些物种中，脂转运蛋白和卵黄原蛋白的内吞作用可能占成熟卵中脂质的10%左右。因此，大部分脂质通过脂转运蛋白介导的途径转运，其中脂蛋白在卵母细胞表面卸载其脂质货物而不发生内化。本章概述了昆虫卵母细胞中脂质储存及其利用的现状，并讨论了包括脂蛋白、转运蛋白、脂解酶和脂质滴等动态细胞器在内的关键因素的参与情况。在卵成熟过程中脂质积累的背景下介绍了脂转运蛋白受体领域的新发现，并从卵子发生和胚胎发生的角度总结了脂质除能量来源之外的作用。最后，提出了未来研究的前瞻性和富有成果的领域。
