A DNA structure found in the soil acts like the Borg from Star Trek, assimilating and integrating traits from other organisms
The Borg, the villains of the classic Star Trek series, were half-machine, half-biological organism aliens who had a single collective collective mind. When they found a new species, they assimilated it, acquiring its characteristics and integrating them into their collective.
Do the Borg live among us? According to a discovery by the researchers at the University of California, there is a similar mechanism that is already at work on Earth.
unique and enigmatic
The scientists who wrote the study happened to find DNA structures in the mud of damp spaces that appeared to collect genes from microorganisms in their environment, much like the Borg from ‘Star Trek’, which is why they named these strands of DNA borgs. extra long.
Fragments of DNA called borgs are linked to a long list of genetic structures known as extrachromosomal elements (ECEs), that is, pieces of DNA that are not part of a chromosome. Another example of these structures are the circular plasmids, present in bacteria. These ECEs act on their own and can self-replicate or insert themselves into a chromosome of the organism that carries them.
Most microbes have one or two chromosomes that encode their primary genetic blueprint, but they can harbor, and often share with each other, many different SCEs. Non-essential but useful genes, such as those for antibiotic resistance, are found in EEC, the study shows. Scientists also use these ECEs, specifically plasmids, for their DNA studies.
As the lead author of the research said, Jill Banfield “Borgs are a previously unknown, unique, enigmatic and absolutely fascinating type of EEC,” and he compares this to the CRISPR discovery.
What distinguishes the Borg from other ECEs is its large size, between 600,000 and a million base pairs of DNA. In fact, they are so large that they are up to a third the length of the main chromosome in their host microbes, Banfield clarified.
The researcher studies how microbes influence the carbon cycle, including the production and degradation of methane, a powerful greenhouse gas, and in October 2019, she and her team went looking for ECEs with genes involved in the carbon cycle. . There, they found the first borgs and identified 19 different types, also other similar locations in Colorado.
Borg seem to be associated with archaea, which are single-celled microorganisms that are not bacteria and form their own kingdom. The findings by these scientists are related to the variety metanoperedens, which digests and destroys methane. Borg genes appear to be involved in this process, explained Banfield.
Borg appear to be associated with single-celled microorganisms known as archaea, shown in this image. Source: Eye of Science / SPL
Keeping the borgs would be too expensive
The report highlights that, in addition to their remarkable size, borgs are distinguished by other structural characteristics. They are linear, not circular like plasmids and many other ECEs. In addition, they have repeating sequences of genes at each end of the strand and many other repeating sequences within and between genes.
While the individual characteristics of the Borg have been seen before, their size, combination and the fact that they contain genes associated with metabolism are what sets them apart, the author explained. She believes they were once whole microbes and were assimilated by archaea in the same way that eukaryotic cells absorbed mitochondria, the energy-generating organelles in every cell in our body, and were once independent bacteria.
The researchers said that maintaining such a large ECE would be very expensive from an energy point of view, so the DNA structures must have some benefit to the organism that harbors them. To find out what it could be, they analyzed the sequences of hundreds of Borg genes and compared them to other known genes.
Help against climate change
By analyzing the borg genome, Banfield saw features that suggest the borgs had taken up genes from a variety of sources, including the archaeal main chromosome. metanoperedens. Precisely this gene assimilation potential led Banfield’s son to propose the name “borg” in 2020.
The team is investigating the role of the Borg and the role of their DNA repeats. Repeats are important for microbes. In the case of CRISPR, the bacteria copy fragments of the genetic code of the viruses that they incorporate in their own DNA to remember pathogens and to be able to defend against them in the future.
This CRISPR “gene copier” is what made biotechnology advance, as it is used as a very precise tool to edit genes, eliminating, for example, those that cause hereditary diseases. This suggests that Borg genomes may also yield useful tools in the future.
Banfield said one possible application the researchers see for these borgs could be an aid in the fight against climate change. Encouraging the growth of microbes that contain them could perhaps reduce methane emissions generated by ground-dwelling archaea, which total about one gigaton worldwide each year.
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