Otospiralin (OTOSP) is a small protein of unknown function, expressed in fibrocytes of the inner ear and required for normal cochlear auditory function. Despite its conservation from fish to mammals, expression of otospiralin was only investigated in mammals. Here, we report for the first time the expression profile of OTOS orthologous genes in zebrafish (Danio rerio): otospiralin and si:ch73-23l24.1 (designated otospiralin-like). In situ hybridization analyses in zebrafish embryos showed a specific expression of otospiralin-like in notochord (from 14 to 48 hpf) and similar expression patterns for otospiralin and otospiralin-like in gut (from 72 to 120 hpf), swim bladder (from 96 to 120 hpf) and inner ear (at 120 hpf). Morpholino knockdown of otospiralin and otospiralin-like showed no strong change of the body structure of the embryos at 5 dpf and the inner ear was normally formed. Nevertheless, knockdown embryos showed a reduced number of kinocilia in the lateral crista, indicating that these genes play an important role in kinocilium formation. RT-qPCR revealed that otospiralin is highly expressed in adult zebrafish inner ear comparing to the others analyzed tissues as previously shown for mice. Interestingly, otospiralin-like was not detected in the inner ear which suggests that otospiralin have a more important function in hearing than otospiralin-like. Phylogenetic analysis of otospiralin proteins in vertebrates indicated the presence of two subgroups and supported the functional divergence observed in zebrafish for otospiralin and otospiralin-like genes. This study offers the first insight into the expression of otospiralin and otospiralin-like in zebrafish. Expression data point to an important role for otospiralin in zebrafish hearing and a specific role for otospiralin-like in notochord vacuolization.

中文翻译：

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斑马鱼otospiralin基因的基因复制和功能差异

Otospiralin（OTOSP）是一种功能未知的小蛋白，在内耳的纤维细胞中表达，是正常的耳蜗听觉功能所必需的。尽管从鱼类到哺乳动物都有保护，但仅在哺乳动物中研究了耳螺菌素的表达。在这里，我们首次报告OTOS直系同源基因在斑马鱼（Danio rerio）：otospiralin和si：ch73-23l24.1（指定为otospiralin-like）中的表达谱。斑马鱼胚胎中的原位杂交分析显示在脊索动物中特定表达了otospiralin-like（从14至48 hpf），otospiralin和otospiralin-like的表达模式相似在肠道（从72至120 hpf），游泳膀胱（从96至120 hpf）和内耳（在120 hpf）下进行。在5 dpf时otospiralin和otospiralin-like的Morpholino抑制作用显示胚胎的身体结构没有强烈变化，并且正常形成了内耳。然而，击倒的胚胎在侧cr中显示出减少的运动蛋白数量，表明这些基因在运动蛋白形成中起重要作用。RT-qPCR显示，与以前分析过的其他组织相比，otospiralin在成年斑马鱼内耳中高表达。有趣的是，内耳未检测到耳螺旋藻样蛋白，这表明耳螺旋藻蛋白在耳中比耳螺旋藻样具有更重要的功能。在脊椎动物中对耳螺旋藻蛋白的系统进化分析表明存在两个亚组，并支持在斑马鱼中观察到耳螺旋藻蛋白和耳螺旋藻样基因的功能差异。这项研究提供了对斑马鱼中otospiralin和像otospiralin-like表达的第一个见解。表达数据指出了耳螺旋藻蛋白在斑马鱼听力中的重要作用，以及耳螺旋藻样蛋白在脊索空泡中的特定作用。