The chimeric genes in the hybrid lineage of Carassius auratus cuvieri (♀)×Carassius auratus red var. (♂)

Hybridization can combine the genomes of different strains or species, which leads to changes of genotype and phenotype in the hybrids. In this study, we aimed to investigate the genetic variations of hybrids (WR-F1 and WR-F2) derived from the intraspecific hybridization of white crucian carp (Carassius auratus cuvieri, WCC, ♀) and red crucian carp (Carassius auratus red var., RCC, ♂). Here, we compared the orthologous genes in the liver transcriptomes of hybrids with those of WCC and RCC, and classified the orthologous genes into eight gene patterns within three categories (chimera, mutant, and biparental origin genes). The results revealed 19.04%, 4.17% chimeric genes and 6.90%, 5.05% mutations of orthologous genes in WR-F1 and WR-F2 respectively. Seventeen of twenty-three characterized genes (77%) were confirmed to be the chimeras at the genomic DNA level. The GO classification discovered that some chimeric and mutant genes were related to metabolic process, immune system and developmental process in WR-F1. Our results provide the new evidence that hybridization can combine the parental genomes, leading to changes in the genotype of the resultant hybrids. This is the first report on the formation of chimeric genes from fish intraspecific hybridization, which is potentially interesting from the context of both evolution and the genetic breeding of fish.