Comparative Genomics Studies on the Gene Family in Fish.

Doublesex and mab-3-related transcription factor () genes are widely distributed across various biological groups and play critical roles in sex determination and neural development. Here, we applied bioinformatics methods to exam cross-species changes in the dmrt family members and evolutionary relationships of the genes based on genomes of 17 fish species. All the examined fish species have while only five species contained Most fish harbored two paralogs ( and ), with being unique to fish. In the phylogenetic tree, 147 DMRT are categorized into eight groups (DMRT1-DMRT8) and then clustered in three main groups. Selective evolutionary pressure analysis indicated purifying selections on genes and the gene cluster. Similar genomic conservation patterns of the gene cluster with 20-kb upstream/downstream regions in fish with various sex-determination systems were observed except for three regions with remarkable diversity. Synteny analysis revealed that , and were relatively conserved in fish during the evolutionary process. While was lost in most species during evolution. The high conservation of the gene cluster in various fish genomes suggests their crucial biological functions while various family members and sequences across fish species suggest different biological roles during evolution. This study provides a molecular basis for fish functional analysis and may serve as a reference for in-depth phylogenomics.