Behold the 'Borg': Massive DNA Structures Perplex Scientists

Tue, 20 Jul 2021 08:00:00 GMT
Scientific American - Science

Researchers say they have discovered unique and exciting DNA strands in the mud; others are not sure...

The Borg have landed-or, at least, researchers have discovered their counterparts here on Earth.

Scientists analysing samples from muddy sites in the western United States have found novel DNA structures that seem to scavenge and 'assimilate' genes from microorganisms in their environment, much like the fictional Star Trek 'Borg' aliens who assimilate the knowledge and technology of other species.

Borgs are DNA structures "Not like any that's been seen before", says Brett Baker, a microbiologist at the University of Texas at Austin.

Their vast size, ranging between more than 600,000 and about 1 million DNA base pairs in length, is one feature that distinguishes Borgs from many other ECEs.

Borg genes seem to be involved in this process, says Banfield.

Scientists can't yet culture Methanoperedens in the laboratory-an ongoing challenge for many microbes-so the team's conclusions that Borgs might be used by the archaea for methane processing are based on sequence data alone.

Assuming Borgs are real, maintaining such a massive ECE would be costly for Methanoperedens, Banfield and colleagues say, so the DNA structures must provide some benefit.

To learn what that might be, the researchers analysed the sequences of hundreds of Borg genes and compared them with known genes.

So what makes a Borg a Borg? In addition to their remarkable size, Borgs share several structural features: they're linear, not circular as many ECEs are; they have mirrored repetitive sequences at each end of the strand; and they have many other repetitive sequences both within and between the presumptive genes.

Banfield's team is now investigating the function of Borgs and the role of their DNA repeats.