Kress Sigrid, Biechl Daniela, Wullimann Mario F
Department Biology II, Biocenter, Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität Munich, Grosshaderner Str. 2, 82152, Planegg-Martinsried, Germany.
Brain Struct Funct. 2015 Jul;220(4):1951-70. doi: 10.1007/s00429-014-0765-1. Epub 2014 Apr 13.
In the zebrafish (Danio rerio) olfactory epithelium, the calcium-binding proteins (CBPs) calretinin and S100/S100-like protein are mainly expressed in ciliated or crypt olfactory sensory neurons (OSNs), respectively. In contrast parvalbumin and calbindin1 have not been investigated. We present a combinatorial immunohistological analysis of all four CBPs, including their expression in OSNs and their axonal projections to the olfactory bulb in larval and adult zebrafish. A major expression of calretinin and S100 in ciliated and crypt cells, respectively, with some expression of S100 in microvillous cells is confirmed. Parvalbumin and calbindin1 are strongly expressed in ciliated and microvillous cells, but not in crypt cells. Moreover, detailed combinatorial double-label experiments indicate that there are eight subpopulations of zebrafish OSNs: S100-positive crypt cells (negative for all other three CBPs), parvalbumin only, S100 and parvalbumin, parvalbumin and calbindin1, and parvalbumin and calbindin1 and calretinin-positive microvillous OSNs, as well as a major parvalbumin and calbindin1 and calretinin, and minor parvalbumin and calbindin1 and calretinin-only-positive ciliated OSN populations. CBP-positive projections to olfactory bulb are consistent with previous reports of ciliated OSNs projecting to dorsal and ventromedial glomerular fields and microvillous OSNs to ventrolateral glomerular fields. We newly describe parvalbumin-positive fibers to the mediodorsal field which is calretinin free, with its anterior part showing additionally calbindin1-positive fibers, but absence thereof in the posterior part, indicating an origin from microvillous OSNs in both parts. One singular glomerulus (mdG2) exhibits S100 and parvalbumin-positive fibers, apparently originating from all crypt cells plus some microvillous OSNs. Arguments for various olfactory labeled lines are discussed.
在斑马鱼（Danio rerio）的嗅觉上皮中，钙结合蛋白（CBP）钙视网膜蛋白和S100/S100样蛋白分别主要表达于纤毛型或隐窝型嗅觉感觉神经元（OSN）中。相比之下，小白蛋白和钙结合蛋白1尚未得到研究。我们对所有四种CBP进行了联合免疫组织学分析，包括它们在幼虫和成年斑马鱼OSN中的表达以及它们向嗅球的轴突投射。证实了钙视网膜蛋白和S100分别在纤毛细胞和隐窝细胞中大量表达，S100在微绒毛细胞中也有一些表达。小白蛋白和钙结合蛋白1在纤毛细胞和微绒毛细胞中强烈表达，但在隐窝细胞中不表达。此外，详细的联合双标记实验表明，斑马鱼OSN有八个亚群：S100阳性隐窝细胞（对其他三种CBP均为阴性）、仅小白蛋白阳性、S100和小白蛋白阳性、小白蛋白和钙结合蛋白1阳性，以及小白蛋白和钙结合蛋白1以及钙视网膜蛋白阳性的微绒毛OSN，还有一个主要的小白蛋白和钙结合蛋白1以及钙视网膜蛋白阳性，以及一个次要的仅小白蛋白和钙结合蛋白1以及钙视网膜蛋白阳性的纤毛OSN群体。CBP阳性向嗅球的投射与先前关于纤毛OSN投射到背侧和腹内侧肾小球区域以及微绒毛OSN投射到腹外侧肾小球区域的报道一致。我们新描述了向中背侧区域的小白蛋白阳性纤维，该区域无钙视网膜蛋白，其前部还显示有钙结合蛋白1阳性纤维，但后部没有，这表明这两部分均起源于微绒毛OSN。一个单独的肾小球（mdG2）显示有S100和小白蛋白阳性纤维，显然起源于所有隐窝细胞以及一些微绒毛OSN。文中讨论了各种嗅觉标记线的相关论据。
