Mitochondria share an ancestor with SAR11, a globally significant marine microbe

Jul 25, 2011

A recent study by researchers at the University of Hawaii, Manoa, and the Oregon State University provides strong evidence that mitochondria share a common evolutionary ancestor with a lineage of marine bacteria known as SAR11, arguably the most abundant group of microorganisms on Earth.

Billions of years ago, an astounding evolutionary event occurred: certain bacteria became obliged to live inside other cells, thus starting a chain of events that resulted in what is now the , an organelle found in all eukaryotic cells.

A recent study by researchers at the University of Hawaii – Manoa (UHM) and the Oregon State University (OSU) provides strong evidence that mitochondria share a common evolutionary ancestor with a lineage of known as SAR11, arguably the most abundant group of on Earth.

"This is a very exciting discovery," says Michael Rappe, Associate Researcher at the Hawaii Institute of Marine Biology in the School of Ocean and Earth Science and Technology (SOEST) at UHM. "The results that we present make sense in a lot of ways: the physiology of SAR11 makes them more apt to be dependent on other organisms, and based on the contemporary abundance of SAR11 in the global ocean, the ancestral lineage may have also been abundant in the ancient ocean, increasing encounters between this bacterial lineage with the host of the original symbiosis event."

In order to understand the evolutionary history of the SAR11 clade of marine bacteria, colleagues at Oregon State University compared the genomics of mitochondria from diverse supergroups of eukaryotes (including Excavata, Chromalveolata, and Archaeplastida) with the genomics of SAR11 strains isolated by Rappe's laboratory using several interconnected computer programs. This approach provided highly sophisticated and thorough phylogenetic analysis of these genomes.

In addition to discovering the evolutionary connection between mitochondria and SAR11, the phylogenomics-based assessment of the diversity of this group (i.e. an assessment based on the entire genome, rather than single genes) provided substantial support for proposing a new family of bacteria, Pelagibacteraceae, fam. nov. "The implication is that the lineage of highly abundant marine bacteria known as SAR11 contains a significant amount of genetic diversity, which potentially indicates significant diversity in metabolism," notes Rappe.

Rappe and colleagues at SOEST and OSU continue to grow new strains of SAR11 and probe their genomes to further understand their metabolic potential and how they have become so successful in the global ocean.

Explore further: Over-organizing repair cells set the stage for fibrosis

More information: Nature Scientific Reports: Phylogenomic evidence for a common ancestor of mitochondria and the SAR11 clade, DOI:10.1038/srep00013

Provided by University of Hawaii

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Vendicar_Decarian
5 / 5 (3) Jul 26, 2011
God put Bacteria in our cells as mitochondria, to test our faith.

Well, your faith actually. I am Pastafarian.
kevinrtrs
1 / 5 (7) Jul 26, 2011
Billions of years ago, an astounding evolutionary event occurred: certain bacteria became obliged to live inside other cell

So who was there to witness this rather miraculous event, to record it for posterity? No one. This is sheer speculation on the author's part. Any inferences made are simply that - inferences. The so-called evidence can be interpreted in other ways which provide better explanations for their existence.
There was no earth billions of years ago, since it only got created about 6000 years ago.
The billions of years are a myth required for evolutionary processes but unfortunately real observational evidence falsifies any notion of Ga.
However, people simply choose to ignore it, lying to themselves that what they are really seeing somehow does not exist.
SCVGoodToGo
5 / 5 (2) Jul 26, 2011
Really Kevin? and what evidence do you provide to either prove your stance or refute theirs? Shame VD's comment went over your head.
Peteri
5 / 5 (1) Jul 26, 2011
Yet again Kevin...

You creationalists believe that 6000 years ago god created the universe for mankind - galaxies, stars, the planets in our solar system, the earth's geology including its myriad fossils, and the huge diversity of life.

However, using this same logic, your deity could equally have been a bit mischievous and finished creating the universe just yesterday with everything ready-made and in place including all our memories, books (e.g. the biblical texts), and everything else in the universe all cunningly contrived to make it appear to have been created 6K years ago.

In fact, why stop at yesterday? Why not have creation complete just a minute ago, or just a fraction of a second ago? After all, your omnipotent god would only need to implant all the self-consistent life-memories right up to the present in everyones minds. This surely reveals the patent absurdity and the anthropocentric fallacy of having some deity create everything ready-made just a few thousand years ago!