416: HGT-chimeras: fusion across the tree of life

Kapoor RR et al., PNAS - A systematic screen of 319 arthropod genomes reveals genes formed by in‑frame fusion of horizontally transferred nonmetazoan sequences with endogenous metazoan regions. Many of these HGT-chimeras are transcribed, conserved, and show coherent domain architectures, implicating them in diverse biological processes. Key terms: horizontal gene transfer, gene fusion, arthropods, novel genes, molecular evolution.

Study Highlights:
The authors developed an intragenic phylogenetic pipeline and screened 319 high-quality arthropod genomes to identify HGT-chimeras. They report 274 chimeric genes corresponding to 104 independent origination events derived from bacteria, viruses, fungi, and plants. RT-PCR and Sanger sequencing validated contiguous chimeric mRNA expression for 36 of 41 tested chimeras, and molecular evolution analyses show widespread purifying selection and functional domain assembly. Evidence indicates gene duplication and postfusion divergence often accompany chimera formation, suggesting a recurrent route to novel gene functions.

Conclusion:
Fusion of horizontally acquired sequences with endogenous metazoan sequences has been a recurrent source of novel genes in arthropods, producing expressed, conserved chimeric proteins that likely contribute to organismal biology and evolution.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
Evolutionary innovation through fusion of sequences from across the tree of life

First author:
Kapoor RR

Journal:
PNAS

DOI:
10.1073/pnas.2602557123

Reference:
Kapoor RR, Rona I, Extavour CG, et al. Evolutionary innovation through fusion of sequences from across the tree of life. Proc Natl Acad Sci U S A. 2026;123(29):e2602557123. doi:10.1073/pnas.2602557123

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

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Episode link: https://basebybase.com/episodes/hgt-chimeras-fusion-across-tree-of-life

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-07-18.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the transcript's core scientific narrative: definition and existence of HGT-chimeras in arthropods; the 319-genome screen; 274 chimeras in 104 origination events; RT-PCR validation (36/41 across 18 species); evidence of purifying selection (dN/dS < 1) and selected exemplars (shrimp, copepod, damselfly, mosquito
- transcript topics: HGT-chimera concept and definition; Scope of arthropod genome survey (319 genomes); Quantitative results (274 chimeras, 104 origination events, 109 HGT intervals); RT-PCR validation and transcriptional evidence (36/41 across 18 species); Purifying selection and dN/dS interpretation; Exemplar cases: shrimp cluster 12, copepod cluster 14, damselfly cluster 41, mosquito cluster 9

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 4
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_tit...