Van Antwerpen R, Conway R, Law J H
Department of Biochemistry, University of Arizona, Tucson 85721.
Tissue Cell. 1993;25(2):205-18. doi: 10.1016/0040-8166(93)90020-l.
The ultrastructure of developing Manduca sexta oocytes is described with respect to the endocytic pathway for protein incorporation. Three major (lipo) protein components of mature M. sexta eggs, lipophorin, vitellogenin and microvitellogenin, were localized along this pathway by immuno-fluorescence and immuno-gold labeling techniques. Labeling of the antigens was observed in the extracellular spaces of the follicle. In those cases where fixation and en bloc staining procedures did not destroy antigenicity, antigens were detected in coated pits and coated vesicles near the plasma membrane of the oocyte. All three antigens were demonstrated to be present in endosomes in the cortex of the oocyte. Both the morphology and the labeling pattern of the endosomes indicate that this organelle is a compartment of uncoupling of receptor and ligand. Tubular elements at the surface of the endosome, interpreted to be involved in the recycling of receptors and membrane to the oocyte surface, were not labeled. Strong labeling of lipophorin, vitellogenin and microvitellogenin was observed in the developing yolk bodies, the main protein storage compartment of the oocyte. The uptake and storage of hemolymph proteins and lipoproteins by M. sexta oocytes is discussed in comparison with other insect and vertebrate endocytic systems.
本文描述了烟草天蛾发育中卵母细胞的超微结构，涉及蛋白质摄入的内吞途径。通过免疫荧光和免疫金标记技术，在这条途径上定位了成熟烟草天蛾卵的三种主要（脂）蛋白成分，即脂转运蛋白、卵黄原蛋白和微卵黄原蛋白。在卵泡的细胞外空间观察到抗原标记。在固定和整体染色程序未破坏抗原性的情况下，在卵母细胞质膜附近的被膜小窝和被膜小泡中检测到抗原。所有三种抗原都被证明存在于卵母细胞皮质的内体中。内体的形态和标记模式都表明这个细胞器是受体与配体解偶联的区室。内体表面的管状结构被认为参与受体和膜向卵母细胞表面的循环利用，但未被标记。在发育中的卵黄小体（卵母细胞主要的蛋白质储存区室）中观察到脂转运蛋白、卵黄原蛋白和微卵黄原蛋白的强标记。将烟草天蛾卵母细胞对血淋巴蛋白和脂蛋白的摄取与储存，与其他昆虫和脊椎动物的内吞系统进行了比较讨论。
