Scientists studying polar microalgae discovered that large amounts of viral genetic material are permanently embedded within the genomes of these organisms—and that many of these viral genes become highly active when environmental conditions change.
Researchers at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science found that polar algae contain extensive integration of viral DNA into their genomes. Remarkably, in one Antarctic species, Chlamydomonas ICE-L, the amount of viral DNA is larger than anything previously reported in a similar organism.
The discovery suggests viruses may play an unexpected role in helping organisms adapt to some of the harshest environments on Earth. Polar microalgae form the base of marine food webs in Arctic and Antarctic ecosystems and are essential to ocean nutrient cycles and carbon production. Understanding how these organisms survive extreme cold, intense ultraviolet radiation and changing environmental conditions could provide new insight into how life adapts to environmental stress and climate change.
“People usually think of viruses purely as disease-causing threats,” said Mohammad Moniruzzaman, senior author of the study and an assistant professor in the Department of Marine Biology and Ecology at the Rosenstiel School. “But our research shows that viral DNA can become part of an organism’s genome and remain active, responding when environmental conditions change.”
The research team analyzed the genomes of nine Arctic and Antarctic microalgae species to search for viral sequences embedded in their DNA. Using specialized bioinformatics tools, the scientists identified hundreds of regions originating from giant viruses that had become permanent parts of the algae’s genomes.
The researchers also discovered that many of these viral genes are not inactive remnants of past infections. Instead, they are actively expressed and respond to environmental stressors such as ultraviolet radiation, temperature changes and high salinity.
“These viral genes are not just sitting quietly in the genome,” said lead author Sydney Schultz, who conducted the research as a graduate student at the Rosenstiel School. “They switch on and off when certain environmental conditions shift, which suggests they may help the algae cope with stressful conditions.”
The study also suggests that giant viruses may act as genetic vehicles that move useful genes between organisms. By transferring beneficial traits—such as genes linked to cold tolerance—viruses may help species adapt to challenging environments.
While the research focuses on microscopic algae, the findings support a broader idea: viruses may serve as a source of genetic innovation that helps organisms adapt to environmental stress.
The study, “Extensive array of endogenous giant viral elements in a polar alga show dynamic transcriptional response to abiotic stress,” was published on March 25 in the journal Current Biology.
Funding for the research was provided by the National Science Foundation Biological Oceanography program (grant #2346438) and a Lang Fellowship from the Phycological Society of America.
The authors of the study include Sydney Schultz, Mohammad Moniruzzaman, Benjamin Minch, and Ethan Mimick of the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science.
