Retroduplication and loss of parental genes is a mechanism for the generation of intronless genes in Ciona intestinalis and Ciona savignyi.
Dev Genes Evol 2014;
224:255-60. [PMID:
25037949 DOI:
10.1007/s00427-014-0475-y]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 07/09/2014] [Indexed: 01/08/2023]
Abstract
Tunicates, the sister clade of vertebrates, have miniature genomes and numerous intronless genes compared to other animals. It is still unclear how the tunicates acquired such a large number of intronless genes. Here, we analyzed sequences and intron-exon organizations of homologous genes from two closely related tunicates, Ciona intestinalis and Ciona savignyi. We found seven cases in which ancestral introns of a gene were completely lost in a species after their divergence. In four cases, both the intronless copy and the intron-containing copy were present in the genome, indicating that the intronless copy was generated by retroduplication. In the other three cases, the intron-containing copy was absent, implying it was lost after retroduplication. This result suggests that retroduplication and loss of parental genes is a major mechanism for the accumulation of intronless genes in tunicates.
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