Foxg1 Genes of Acipenseriformes Support a Model of Ancestral Genomic Duplication Followed by Asynchronous Rediploidization.

Gene foxg1 is one of the key regulators of the early differentiation and development of the vertebrate forebrain and associated sensory organs. In this article, the presence of five foxg1 paralogs in Acipenseriformes, one of the evolutionarily ancient branches of gnathostomes, is described. The appearance of multiple paralogs in Acipenseriformes was apparently associated with three rounds of whole-genome duplications (WGDs), two of which occurred early in the evolution of gnathostomes and are common to the entire clade, while the third is specific to sturgeons. The goal of the work was to study the orthology of the foxg1 of Acipenseriformes with the foxg1 of other groups of vertebrates and to identify their relationship with the development of individual morphological structures by studying spatial expression. The phylogenetic analysis showed that the foxg1b genes of sturgeons occurred as a result of duplication in the common ancestor of the group, while the foxg1a paralogues appeared as a result of independent rediploidizations in the Acipenser and Polyodon lineages. These data are consistent with a model of ancestral duplication followed by asynchronous rediploidization and support duplication at the level of the common ancestor of sturgeons. The studied expression patterns indicate spatial subfunctionalization of foxg1 paralogs in Acipenseriformes and confirm the connection of foxg1 with the development of the forebrain, sensory organs, and associated cranial ganglia in Acipenseriformes as one of the archaic groups of vertebrates. [ABSTRACT FROM AUTHOR]