In teleost fishes, there are three immunoglobulin isotypes named immunoglobulin M (IgM), D (IgD), and T (IgT). IgT was the last to be described in teleost fishes, and it is specific to them. From recent fish genomes, we identified and studied the immunoglobulin heavy chain genes in Actinopterygii. For this analysis, a custom bioinformatics and machine learning pipeline, we call CHfinder, was developed that identifies the exons coding for the CH domains of fish immunoglobulins. Some IgT in teleost and holostean fish found from this systematic study have not been previously described. Phylogenetic analysis of the deduced amino acid sequences of the IgT CH1 exons reveals they are similar to the CH1 of IgM. This analysis also shows that the other three domains (CH2, CH3, and CH4) were not the result of recent IgM duplication processes in Actinopterygii, demonstrating that it is an immunoglobulin of earlier origin. The bioinformatics program, CHfinder, is publicly available at https://github.com/compimmuno/CHfinder.

在硬骨鱼类中，存在三种免疫球蛋白同种型，分别称为免疫球蛋白M（IgM），D（IgD）和T（IgT）。IgT是硬骨鱼类中最新描述的一种，它是特定于它们的。从最近的鱼类基因组中，我们鉴定并研究了放线菌中的免疫球蛋白重链基因。为了进行此分析，开发了一个定制的生物信息学和机器学习管道，我们称为CHfinder，该管道可识别编码鱼免疫球蛋白CH结构域的外显子。以前没有描述过从该系统研究中发现的硬骨鱼和纯种鱼类中的一些IgT。对IgT CH1外显子推导的氨基酸序列进行系统进化分析，发现它们与IgM的CH1相似。此分析还表明，其他三个域（CH2，CH3，和CH4）不是放线菌属中最近的IgM复制过程的结果，表明它是一种较早起源的免疫球蛋白。生物信息学程序CHfinder可在https://github.com/compimmuno/CHfinder上公开获得。