Headline: Cockroaches Harbor Thousands of Hidden Genes from Ancient Bacteria
A new study reveals that cockroach genomes are packed with tens of thousands of DNA fragments from a single bacterium, far exceeding any known rate of horizontal gene transfer in animals.
The Discovery
A study led by researchers from the University of Sydney has identified extensive horizontal gene transfer (HGT) from the bacterium Blattabacterium cuenoti into cockroach genomes. The team found a total of 40,485 fragments of bacterial DNA distributed across the genomes of 18 different cockroach and termite species.
Key Findings
The researchers analyzed the complete genomes of 18 insect species, including termites—which share a common ancestor with cockroaches but have since lost the B. cuenoti symbiont. By focusing on previously overlooked, small, non-coding DNA fragments, they made a startling discovery:
- The number of HGT events per insect ranged from 93 to 4,900. This shatters the previous record of fewer than 300 HGT events found in any single eukaryote.
- Some of these DNA inserts appear to have persisted for at least 28.7 million years.
A New Perspective on Genome Evolution
According to the researchers, these fragments may serve a variety of purposes. They could be functional, neutral, or even slightly deleterious. The study suggests that HGT in eukaryotes is far more pervasive than previously understood, with potential implications for adaptation and the process of speciation.
Publication and Next Steps
The findings were published in the journal PNAS. Looking ahead, the research team plans to determine if any of these transferred DNA fragments have functional effects on the insects that carry them.