Self-replicating DNA elements called “introners” appear to play a significant role in shaping the genomes of diverse eukaryotes, according to a new study published in Proceedings of the National Academy of Sciences. Researchers at the University of California, Santa Cruz have shown that these elements not only duplicate within genomes, but can also jump between unrelated species.
“[Introners are] a way that genome architectures and complexity arise, but not necessarily because there is natural selection that favors this complexity,” said Russ Corbett-Detig, senior author of the study. “A few may ultimately benefit the host, but most are just cheaters that found a really good way to hide in the genome.”
Unlike functional genes, introners do not encode proteins. Instead, they belong to a class of transposable elements that propagate by copying and inserting themselves into new genomic locations. The team searched more than 8,700 eukaryotic genomes and identified over 1,000 distinct introner families. These were especially common in algae, fungi, and single-celled eukaryotes, though examples were also found in animals such as sea urchins and tunicates.
The researchers uncovered eight clear cases of horizontal gene transfer, with one involving a sea sponge and a dinoflagellate sharing a common ancestor more than 1.6 billion years ago. They suggest that large viruses may have facilitated this genetic exchange.
“Because transposons are insanely diverse and present in basically every eukaryote, it implies that this really can be a very general way that new introns arise in different lineages,” Corbett-Detig said. This work adds to ongoing efforts to understand how genomes accumulate complexity and may support future investigations into alternative splicing and its links to disease.
Publication Details
L. Gozashti, A. Nakamoto, S. Russell, & R. Corbett-Detig, Horizontal transmission of functionally diverse transposons is a major source of new introns, Proc. Natl. Acad. Sci. U.S.A. 122 (21) e2414761122, https://doi.org/10.1073/pnas.2414761122 (2025).
“[Introners are] a way that genome architectures and complexity arise, but not necessarily because there is natural selection that favors this complexity,” said Russ Corbett-Detig, senior author of the study. “A few may ultimately benefit the host, but most are just cheaters that found a really good way to hide in the genome.”
Unlike functional genes, introners do not encode proteins. Instead, they belong to a class of transposable elements that propagate by copying and inserting themselves into new genomic locations. The team searched more than 8,700 eukaryotic genomes and identified over 1,000 distinct introner families. These were especially common in algae, fungi, and single-celled eukaryotes, though examples were also found in animals such as sea urchins and tunicates.
The researchers uncovered eight clear cases of horizontal gene transfer, with one involving a sea sponge and a dinoflagellate sharing a common ancestor more than 1.6 billion years ago. They suggest that large viruses may have facilitated this genetic exchange.
“Because transposons are insanely diverse and present in basically every eukaryote, it implies that this really can be a very general way that new introns arise in different lineages,” Corbett-Detig said. This work adds to ongoing efforts to understand how genomes accumulate complexity and may support future investigations into alternative splicing and its links to disease.
Publication Details
L. Gozashti, A. Nakamoto, S. Russell, & R. Corbett-Detig, Horizontal transmission of functionally diverse transposons is a major source of new introns, Proc. Natl. Acad. Sci. U.S.A. 122 (21) e2414761122, https://doi.org/10.1073/pnas.2414761122 (2025).