Inka box actin regulator 1 (Inka1) is a novel protein identified in Xenopus and is found in vertebrates. While Inka1 is required for facial skeletal development in Xenopus and zebrafish, it is dispensable in mice despite its conserved expression in the cranial neural crest, indicating that Inka1 function in facial skeletal development is not conserved among vertebrates. Zebrafish bears two paralogs of inka1 (inka1a and inka1b) in the genome, with the biological roles of inka1b barely known. Here, we analyzed the expression and function of inka1b during facial skeletal development in zebrafish. inka1b was expressed sequentially in the head mesoderm adjacent to the pharyngeal pouches essential for facial skeletal development at the stage of arch segmentation. However, a loss-of-function mutation in inka1b displayed normal head development, including the pouches and facial cartilages. The normal head of inka1b mutant fish was unlikely a result of the genetic redundancy of inka1b with inka1a, given the distinct expression of inka1a and inka1b in the cranial neural crest and head mesoderm, respectively, during craniofacial development. Our findings suggest that the inka1b expression in the head mesoderm might not be essential for head development in zebrafish.

Inka box 肌动蛋白调节因子 1 (Inka1) 是一种在非洲爪蟾中发现的新型蛋白质，存在于脊椎动物中。虽然 Inka1 是非洲爪蟾和斑马鱼面部骨骼发育所必需的，但它在小鼠中是可有可无的，尽管它在颅神经嵴中的表达保守，这表明 Inka1 在面部骨骼发育中的功能在脊椎动物中并不保守。斑马鱼在基因组中带有两个 inka1 旁系同源物（ inka1a和inka1b ） ，而inka1b的生物学作用几乎不为人所知。在这里，我们分析了斑马鱼面部骨骼发育过程中inka1b的表达和功能。墨卡1b在弓分割阶段面部骨骼发育所必需的咽袋附近的头部中胚层中依次表达。然而，inka1b中的功能丧失突变显示出正常的头部发育，包括小袋和面部软骨。inka1b突变鱼的正常头部不太可能是inka1b与inka1a遗传冗余的结果，因为在颅面发育过程中， inka1a和inka1b 分别在颅神经嵴和头部中胚层中的不同表达。我们的研究结果表明inka1b头部中胚层的表达对于斑马鱼的头部发育可能不是必需的。