American biologists have discovered signs of living things in giant viruses. The results of a study by scientists from the Virginia Polytechnic University are published in the journal Nature Communications.
Giant viruses were discovered only in 1992 – they are ten times larger than ordinary viruses, and their genomes are so large that they have always been attributed to bacteria and have hardly been studied. At the same time, if an ordinary virus is not considered a living creature for a number of reasons, then giant viruses gradually discover features that are characteristic only of living organisms.
In particular, in their complex genome, scientists have discovered genes that can control metabolic processes, although the giant viruses themselves have no metabolism. However, other types of viruses do not have such genes.
The researchers analyzed publicly available metagenome databases from which they put together the putative genomes of 501 different types of giant viruses belonging to the group of large nuclear-cytoplasmic DNA-containing viruses (NCLDV), mainly living in the aquatic environment. Scientists worked only with those DNA sections that contained at least four of the five genes characteristic of NCLDV and had at least 100 thousand base pairs.
It turned out that giant viruses carry a huge variety of genes involved in aspects of cellular metabolism, including processes such as absorption of nutrients, light collection, and nitrogen metabolism.