Classical cadherin gene family relies on calcium ions in playing an important role in adhesion between cells. However, comprehensive studies to identify classical cadherin gene families in Nile tilapia (Oreochromis niloticus) have not been conducted. In this study, 18 classical gene family members were screened from Nile tilapia using various bioinformatics methods. These screened cadherins were randomly scattered across eight different linkage groups and shared a conserved LDRE motif. A phylogenetic tree was constructed to explore the evolution of classical cadherin members. The result showed that all classical cadherins were clustered together to form an independent subfamily. In addition, MEME analysis indicated that almost all the screened cadherins had similar motif arrangements. Also, neural-cadherin has up to eight closely adjacent tandem trisomy motif repeats. Finally, the sequence characteristics of cadherin-1 (Oncdh1) associated with pathogen invasion were discussed. The open reading frame of Oncdh1 was 2052 bp, encoding sequences of 683 amino acids with three conserved domains: cadherin repeat-like domain, cadherin prodomain, and cadherin tandem repeat domain. Real-time PCR experiments were carried out to detect the expression pattern of Oncdh1 in head kidney, brain, intestine, and spleen after Streptococcus agalactiae infection. The results showed a significant induction or downregulation of the expression level of Oncdh1 compared with the control group. Overall, the findings of this study might provide a reference for further research on the function of classical cadherin family of Nile tilapia in the future.

经典的钙粘蛋白基因家族依赖钙离子在细胞之间的粘附中起重要作用。然而，全面的研究，以确定尼罗罗非鱼（Oreochromis尼罗罗非鱼）中经典钙粘蛋白基因家族）尚未进行。在这项研究中，使用各种生物信息学方法从尼罗罗非鱼中筛选了18个经典基因家族成员。这些筛选的钙粘着蛋白随机分布在八个不同的连接基团中，并共享一个保守的LDRE基序。构建了系统发育树，以探索经典钙粘蛋白成员的进化。结果表明，所有经典钙粘蛋白都聚在一起形成一个独立的亚科。此外，MEME分析表明，几乎所有筛选的钙粘蛋白都具有相似的基序排列。而且，神经钙粘蛋白最多具有八个紧密相邻的串联三体性基序重复序列。最后，讨论了与病原体入侵相关的钙黏着蛋白1（Oncdh1）的序列特征。的开放阅读框Oncdh1是2052 bp，编码683个氨基酸的序列，具有三个保守域：钙粘着蛋白重复序列​​样结构域，钙粘着蛋白前结构域和钙粘着蛋白串联重复结构域。进行实时PCR实验以检测无乳链球菌感染后Oncdh1在头肾，脑，肠和脾中的表达模式。结果显示，与对照组相比，Oncdh1的表达水平有明显的诱导或下调。总体而言，本研究结果可能为将来进一步研究尼罗罗非鱼经典钙黏着蛋白家族的功能提供参考。