How complex life evolved: Ancient microbes provide clues, Queen Mary University of London

Researchers at Queen Mary University of London have discovered that single-celled organisms incorporate genetic information from ancient giant viruses into their own genes, shedding light on how this influenced the evolution of complex life. This study was published in the journal Science Advances and provides a new perspective on the evolutionary history of complex life.

The subject of the study was Amebidium, a single-celled parasitic organism that lives in freshwater environments. A research team led by Dr. Alex de Mendoza Soler of the School of Biological and Behavioural Sciences at Queen Mary University analyzed the Amebidium genome and discovered that it contains large amounts of genetic material derived from giant viruses. These virus-derived genes are chemically methylated, which typically serves to suppress gene expression.

"It's like finding viral insertions hiding like a Trojan horse inside the DNA of Amebidium," explains Dr. de Mendoza Soler. "These viral insertions are potentially harmful, but Amebidium seems to be chemically suppressing them."

Furthermore, the research team compared the genomes of multiple Amebidium to investigate how widespread this phenomenon is. The results showed significant variation in viral content, suggesting that the process of viral integration and suppression is ongoing and dynamic.

"These findings overturn our understanding of the relationship between viruses and their hosts," says Dr. de Mendoza Soler. "Traditionally, viruses have been viewed as invaders, but this study suggests a more complex story. Viral insertions may have helped in the evolution of complex organisms by providing new genes. And this is made possible by chemically suppressing the DNA of these invaders."

The discovery in Amebidium provides an interesting parallel to how our own genomes interact with viruses. Like Amebidium, humans and other mammals have incorporated remnants of ancient viruses called endogenous retroviruses into their DNA. These remnants were previously dismissed as 'junk DNA,' but it is now suggested that some may be beneficial. However, unlike the giant viruses seen in Amebidium, endogenous retroviruses are much smaller, and the human genome is significantly larger. Future research is expected to explore these similarities and differences to gain a deeper understanding of the interaction between viruses and complex life forms.

For more details, please refer to the original article provided by Queen Mary University of London.

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