Fragile X syndrome (FXS) is a heritable mental retardation disease caused by unstable trinucleotide repeat sequences in FMR1. FXS is characterized by delayed development, hyperactivity, and autism behavior. Zebrafish is an excellent model to study FXS and the underlying function of fmr1. However, at present, fmr1 function is mainly studied via morpholinos or generated mutants using targeting induced local lesions in genomes. However, both of these methods generate off-target effects, making them suboptimal techniques for studying FXS. In this study, CRISPR/Cas9 technology was used to generate two zebrafish fmr1 mutant lines. High-throughput behavior analysis, qRT-PCR, and alcian blue staining experiments were employed to investigate fmr1 function. The fmr1 mutant line showed abnormal behavior, learning memory defects, and impaired craniofacial cartilage development. These features are similar to the human FXS phenotype, indicating that the fmr1 mutant generated in this study can be used as a new model for studying the molecular pathology of FXS. It also provides a suitable model for high-throughput screening of small molecule drugs for FXS therapeutics.

中文翻译：

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斑马鱼fmr1突变幼虫的活动过度，记忆缺陷和颅面异常。

脆性X综合征（FXS）是由FMR1中不稳定的三核苷酸重复序列引起的遗传性智力低下疾病。FXS的特征是发育迟缓，活动过度和自闭症行为。斑马鱼是研究FXS和fmr1潜在功能的出色模型。然而，目前，fmr1功能主要是通过吗啉代菌或通过使用靶向诱导的基因组局部损伤产生的突变体来研究的。但是，这两种方法都会产生脱靶效应，使它们成为研究FXS的次佳技术。在这项研究中，CRISPR / Cas9技术被用于生成两条斑马鱼fmr1突变株。高通量行为分析，qRT-PCR和阿尔辛蓝染色实验用于研究fmr1功能。fmr1突变株表现出异常行为，学习记忆缺陷，和颅面软骨发育受损。这些特征与人的FXS表型相似，表明该研究中产生的fmr1突变体可以用作研究FXS分子病理学的新模型。它还为高通量筛选FXS治疗药物的小分子药物提供了合适的模型。