Monday, February 07, 2011

Is it time to refer to mitochondria as bacteria?

Any time a scientific article has in the summary a sentence like the one below, I am attracted to it:
"Here, I playfully explore the arguments for and against a phylogenetic fundamentalism that states that mitochondria are bacteria and should be given their own taxonomic family, the Mitochondriaceae."
So how could I not want to read this: Trends in Microbiology - Time to recognise that mitochondria are bacteria?:

Well, one reason is that it had been unavailable outside of the TIM paywall. However, the author, Mark Pallen, with a little prodding from me, managed to get the Editors to feature it as a "free" article on their website for at least some time. So everyone, download this paper and distribute it to as many as you can (legally). Oh, and read it, it is definitely worth a read.

In the article Pallen argues for giving mitochondria their own family w/in bacteria. I think that would be a good idea as they are really just a highly reduced form of bacteria. We give endosymbionts, even those with tiny genomes, their own groups. So why note organelles that are derived from bacteria? After all - phylogenetically they are bacteria.

Pallen even goes so far as to suggest rethinking of mitochondria as bacteria will help with efforts to engineer mitochondria in various ways. That is an interesting notion.

I suppose one could push this to an extreme position and argue that the nucleus and all the genes associated with it are really just a shell around a mitochondrial core. And then I guess all eukaryotes could be considered bacteria. But I do not want to confuse the issue too much here. Overall, I really really like this paper. I wish it were in an OA journal, but since it is free for now I think it is worth checking out. In the long run, it would be better (hint hint Mark Pallen) to publish such thought provoking pieces in places everyone can access ....

So I guess this paper, along with all the "microbiome" stuff means that humans are really just carrying vessels for bacteria.





13 comments:

  1. Interesting, but then what about when we start talking about the even more reduced forms such as Hydrogenosomes and Mitosomes that have lost their genomes altogether.

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  2. Puppet bacteria? If some bacterial derived genes are in the host genome and those are used to run the hydrogenosome ....

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  3. Pretty soon, maybe people will think viruses are alive.

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  4. I find the statement that "humans are really just carrying vessels for bacteria" underestimates the contribution of fungi. I carry my yeast in vessels daily...

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  5. I am so sorry Jim - I should have been more inclusive

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  6. @Stephen Actually, some of the viral ecology people next door argue that the live virus component is the infected cell, with the virion itself analogous to a spore; much like a seed by itself is incapable of doing much on its own and needs a specific environment to be a full-fledged living organism, the virus only becomes properly 'alive' upon infecting the cell, with the hijacked cell as the viral organism.

    Don't know how much I buy that (don't really care, personally, given I don't work on viruses), but a really cool way of looking at things nonetheless, IMO...

    As for the mitochondrion, I call them 'bacteria'/'endosymbionts' when among cell biologists, and 'organelles' when hanging out with the endosymbiosis people, to piss off the most people at once. I particularly like to call sketchy cases of endosymbiosis like Paulinella's cyanelles and Neoparamoeba's Perkinsela symbiont "organelles" to piss off people like Bill Martin... =P
    Trolling scientists is so much fun! >.>

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  7. I sympathize with your wish that it would be in an OA journal, but for such pieces, I'm not sure what alternative to the Trends series there really is. I try to publish my original research OA every time I have a choice, but I've used Trends several times for articles which I do not feel would have a home elsewhere, or else would lose considerably in visibility to the core target, my colleagues.
    Incidentally, Trends does allow you to distribute a preprint on your webpage, which I do. To quote from Sherpa/Romeo:
    "author can archive post-print (ie final draft post-refereeing)"
    But I suppose that my point is to ask, when do we get PLoS Trends?

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  8. @Jonathan Now I'm picturing Hydrogenosomes as marionettes, with the genome holding the strings. Dance organelles dance!

    @Psi Good strategy to get a rise out of people. :)

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  9. Hi,

    I followed your suggestion and read the paper. I enjoyed reading it. However I do think that changing the name does not change the way we think of mitochondria, since their bacterial nature is already widely recognized.

    I made a blog entry on this:

    http://treevolution.blogspot.com/2011/02/on-debate-of-recognising-mitochondria.html

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  10. Hi Jonathan,

    I recently published in Trends in Microbiology after a failed attempt to publish in an OA journal (not yours btw). I am a postdoc without my own funding, and the paper was on a topic unrelated to my (and my PI's) current project. I was offered a publication fee discount of 100 or so dollars, meaning that I still had to pay 1300 dollars of my own money, which, unsuprisingly, did not win me over. It seems that OA journals are a good option when you are either rich or poor but not so good when you fall somewhere inbetween.

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  11. Michiel

    Clearly that is less than ideal. But it is a symptom of a broken system since the total amount of money spent to read your paper was probably higher than the OA fee you could not afford. It would be better for science as a whole to reallocate the $$ spent on subscriptions to journals to help cover OA publishing for the scientific middle class

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  12. Cheers for this. My two pennies is that a mitochrion is a mitochondrian, not a bacterium and more than a organelle. It has has evolved from bacteria, but is now something quite different that does deserve its own lineage.

    I found the last two paragraphs really interesting, does anyone know more the possibly of cloning into mitochondria? Is there some literature floating around?

    Cheers! I'll be sure to check this blog again :-)

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  13. The semantics of classification usually put me to sleep. This is much more interesting as a question of symbiotic evolution and mechanisms of recombination and gene transfer.

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