Serial electron microscopic reconstruction of the drosophila larval eye: Photoreceptors with a rudimentary rhabdomere of microvillar-like processes.
Serial electron microscopic reconstruction of the drosophila larval eye: Photoreceptors with a rudimentary rhabdomere of microvillar-like processes.
复制标题
果蝇幼虫眼的系列电子显微镜重建：具有微绒毛状突起的基本横纹肌的光感受器。
DOI：
10.1016/j.ydbio.2019.05.017
复制
发表时间：
2019
影响因子：
2.7
通讯作者：
Knust,Elisabeth
中科院分区：
文献类型：
--
作者：
Hartenstein,Volker;Yuan,Michaela;Younossi-Hartenstein,Amelia;Karandikar,Aanavi;Bernardo-Garcia,FJavier;Sprecher,Simon;Knust,Elisabeth
光感受器细胞（PRCs）在动物界的特点是堆叠顶端膜，以适应高丰度的色素。在节肢动物和许多其他无脊椎动物门中，PRC膜堆叠采用密集堆积的微绒毛的形状，形成称为横纹肌的结构。PRCs和周围的辅助细胞，包括色素细胞和晶状体形成细胞，被分组在刻板的单位，小眼。在全变态昆虫的幼虫中，眼睛（称为stemmata）在小眼的数量和组成方面减少。果蝇的干细胞（Bolwig器官）退化为两侧表皮下PRCs簇，缺乏所有其他细胞类型。本文分析了果蝇幼鱼PRCs的发育和精细结构。在胚胎头部外胚层出现后不久，PRC前体分层并失去上皮细胞顶端标志物的表达，包括Crumbs和几种中心体相关蛋白。在早期的一龄幼虫，PRCs显示出一个扩大的，不规则形状的顶端表面，折叠成多个水平的微绒毛状突起（MLP）。顶端PRC膜和MLP覆盖着一层细胞外基质。MLP主要沿腹前向背后延伸的轴沿着排列，但长度、直径和间距不同。单个MLP呈现“珠状”形状，厚段（直径0.2-0.3 μm）与薄段（>0.1 μm）交替。我们表明，糖蛋白Chaoptin，这是绝对必要的横纹肌形成在成人PRCs的损失，不会导致严重的异常幼虫PRCs。
Photoreceptor cells (PRCs) across the animal kingdom are characterized by a stacking of apical membranes to accommodate the high abundance of photopigment. In arthropods and many other invertebrate phyla PRC membrane stacks adopt the shape of densely packed microvilli that form a structure called rhabdomere. PRCs and surrounding accessory cells, including pigment cells and lens-forming cells, are grouped in stereotyped units, the ommatidia. In larvae of holometabolan insects, eyes (called stemmata) are reduced in terms of number and composition of ommatidia. The stemma ofDrosophila(Bolwig organ) is reduced to a bilateral cluster of subepidermal PRCs, lacking all other cell types. In the present paper we have analyzed the development and fine structure of theDrosophilalarval PRCs. Shortly after their appearance in the embryonic head ectoderm, PRC precursors delaminate and lose expression of apical markers of epithelial cells, including Crumbs and several centrosome-associated proteins. In the early first instar larva, PRCs show an expanded, irregularly shaped apical surface that is folded into multiple horizontal microvillar-like processes (MLPs). Apical PRC membranes and MLPs are covered with a layer of extracellular matrix. MLPs are predominantly aligned along an axis that extends ventro-anteriorly to dorso-posteriorly, but vary in length, diameter, and spacing. Individual MLPs present a “beaded” shape, with thick segments (0.2–0.3 μm diameter) alternating with thin segments (>0.1 μm). We show that loss of the glycoprotein Chaoptin, which is absolutely essential for rhabdomere formation in the adult PRCs, does not lead to severe abnormalities in larval PRCs.