Viruses of impressive size have been found on the surface of the Greenland ice sheet. Their occurrence is likely linked to the presence of snow algae – algae that inhabit the coldest regions of the world, which during bloom accelerate the melting of the ice cover. Knowing how to control these microbes can help reduce ice loss.
Every spring in the Arctic represents a return to life after months of darkness. In addition to the majestic mammals and birds, the sun also awakens rapidly growing algae. This growth, called bloom, darkens large areas of ice. This has a direct impact on the condition of the ice sheet, as dark ice reflects less light and melts faster. A study recently published in the journal Microbiome showed that its evolution may be linked to the presence of other microorganisms – whether very small or very large…
Giants from Greenland
Dr. Laura Perini of the School of Environmental Sciences at Aarhus University in Denmark and her colleagues found giant viruses in Greenland’s ice. Typical viruses with a diameter of 20-200 nanometers are much smaller than bacteria with a diameter of 2-3 micrometers. The microbes discovered in Greenland are up to 2.5 micrometres in size, which means they are larger than most types of bacteria. Not only is it impressive in size, but its genome is much larger than that of regular viruses. Although viruses are large in their class, they are not large enough to be seen with the naked eye.
Giant viruses were first discovered in 1981 in the ocean, where they infected algae. Later, such viruses were found in soil on Earth and even in humans. Now, for the first time, their presence has been demonstrated on the surface of ice and snow inhabited by microscopic algae.
We discovered viruses by analyzing all the DNA found in the samples collected. The author of the study explained that by searching this huge data set for specific genes, we found sequences that are very similar to known giant viruses.
Melting ice cap near Kangerlussuaq, Greenland – photo. IllustrativeStock struggle
Viruses are self-sufficient
To confirm that the viral DNA did not come from long-dead microbes, but rather from living and active microbes, mRNA molecules were also taken from the sample. When the DNA sequences that make up genes are activated, they are transcribed into single pieces called mRNA. These elements are instructions for building proteins, and if they are present, the virus is active.
Ordinary viruses are unable to transcribe on their own from double-stranded DNA into single-stranded mRNA, which is necessary for the formation of proteins. To do this, they use the capabilities of the infected cell. On the other hand, giant viruses are self-sufficient, although it is not yet known how they manage to do so.
-We found the same marks in the total RNA sequenced from the samples as in the total DNA, so we know they were transcribed. Perini pointed out that this means that viruses are active on ice. She added that these viruses can infect algae and serve as a natural mechanism to control algal blooms.
We don’t know much about these viruses, but I think they could be useful as a way to mitigate ice melt caused by algal blooms. We don’t know how specific it is and how effective it is yet. The researcher added that by examining it closely, we hope to answer some of these questions
Main image source: Stock struggle
