The ability of these tiny organisms to change and adapt to different environments has been a mystery.
New research shows that tinybacteria exchange genetic information with one another even when separated This allows them to transmit whole blocks of genes, such as those that allow them to metabolize a particular kind of food, even in areas with a relatively small population.
A new class of genetic agents involved in horizontal gene transfer is described in the findings. The agents that carry out this transfer are called "tycheposons" because they contain several entire genes and can spontaneously separate out from the surrounding DNA. They can be transported to other organisms by one or another possible carrier system that has small bubbles in it.
The research, which included studying hundreds of Prochlorococcus genomes from different ecosystems around the world, as well as lab-grown samples of different variant, is reported today in the journal Cell.
The new findings explain a lot of the patterns that we see in Prochlorococcus and they are excited about it. The smallest of all photosynthesizers is thought to be the world's most abundant photosynthetic organisms.
Hackl, who is now at the University of Groningen in the Netherlands, says the work began by studying the 623 reported genome sequence of different species of Prochlorococcus from different regions, trying to figure out how they were able to so easily lose or gain certain functions despite their apparent lack
There were islands of genetic material that seemed to be hotspots of variability and often contained genes that were associated with certain survival processes. The islands contained genes that differed enormously between different species, but they always occurred in the same parts of the genome and sometimes were nearly identical even in widely different species.
The genomes did not show any of the usual features associated with mobile genetic elements. Several other mechanisms that have been observed in other organisms, including in humans, have been found to be different in this system.
According to Hackl, what they found was a genetic LEGO set, with chunks of DNA bundled together in ways that could almost instantly give the ability to adapt to a particular environment. It is possible for a species limited by the availability of certain nutrients to acquire genes that will increase their ability to take certain vitamins.
The name Tycheposons is derived from the name of the Greek goddess Oceanus. One way to release tycheposons is by releasing bubbles from the surface of a bacterium. They can carry the tycheposons along with their own infectious particles, called capsids, by hijackingviruses. In the open ocean, it's difficult for these cells to exchange genetic information without a vehicle.
Hackl says they're enriched in the genetic elements when they're studied. The packets of genetic coding can be taken up by other cells.
There are a lot of different types of elements in the world of genetics. This is a new type. It's a family of mobile genetic elements. It is similar to others, but not really close to any of them.
The team believes that the phenomenon may be more generalized. Similar genetic elements have been found in other marinebacteria, but have not yet been analyzed. "Analogous elements have been described in otherbacteria, and we believe that they may function similarly," he says.
He says it's a plug-and-play mechanism where you can play with different pieces. With a large population of Prochlorococcus, it can try a lot of different combinations.
The discovery of tycheposons is important and exciting because it provides a new mechanistic understanding of how Prochlorococcus are able to swap in and out new genes. There is a new mechanistic explanation for how it is done. He says that they took a creative way to find the new genetic elements in Prochlorococcus.
He says that future work on tycheposons has wider implications for our understanding of the evolution ofbacteria's genomes.
The team included researchers at MIT's Department of Civil and Environmental Engineering, the University of Wrzburg in Germany, the University of Hawaii at Manoa, Ohio State University, OxfordNanopore Technologies in California, and Wellesley College.
There is more information about Thomas Hackl and his colleagues. There is an article in the journal Cell.
Journal information: Cell
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