Gigantic Bacteria has 300 Times More DNA than Human Cells

_{May 4, 2007

Biology, Intelligent Design, Science}

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Giant Bacteria over half a millimeter long (visible to the naked eye) living in the gut of surgeonfish is found to have over 300 times more DNA (1 trillion base pairs) than humans (3 billion base pairs). I believe this is now the largest known amount of DNA in a single cell having knocked aside the previous record holder amoeba dubia at ~200 times more DNA than humans.

Comments

Bob I read that DNA is compressed and decompressed on a daily basis, not that the number of base pairs increases and decreases on a daily basis. The amount of DNA varies linearly with cell volume over the entire range of sizes this bacteria can grow to but that isn't talking about daily expansion and contraction. I read that its mode of reproduction is to divide the cell contents up into up to twelve daughter cells completely contained by the maternal cell which then bursts, killing the maternal cell and releasing all the daughters. The daughters are presumably 12 times smaller than the maternal cell with 12 times less DNA. http://www.micro.cornell.edu/cals/micro/research/labs/angert-lab/index.cfm Be that as it may it is still a single cell containing up to a trillion base pairs of DNA.DaveScot_{May 6, 2007
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Dave - there's no evidence that the bacterium doesn't have streamlined DNA. What's going on is that the bacterium is replicating its whole genome up to 3000 times: if anything this would suggest that the genome should be more streamlined. Looking a bit further, I found this article: Bresler, V., Montgomery, W.L., Fishelson, L. and Pollak, P.E. (1998). Gigantism in a Bacterium, Epulopiscium fishelsoni, Correlates with Complex Patterns in Arrangement, Quantity, and Segregation of DNA. Journal of Bacteriology, 180, 5601-5611. which shows that DNA content is proportional to cell volume. It also shows (and I find this really cool) that cell size and DNA content vary diurnally, with cells being largest in the afternoon (about 4pm). This is the time of day when the host is most active, suggesting (to me, at least) that it might be a response to whatever the host is eating during the day. BobBob O'H_{May 5, 2007
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BobOh The point here is mostly about how much DNA a single cell can carry around and still survive. This is a new high water mark - 1 trillion base pairs. Most surprising it isn't a big eukaryotic cell but a big bacteria. The last place we'd expect as bacteria generally have very streamlined DNA - hundreds of coding genes and little else.DaveScot_{May 5, 2007
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One thing to note is that despite the amount of DNA, the bacteria is still bacteria. Hasn't turned into a mushroom or pelican yet.shaner74_{May 5, 2007
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What im curious to see is: Will a genome streamlining process -GREATLY- cut off the excess? Or will the excess turn into new things? IMO, if it is shown that the loss of genetic material is the rule, and after several generations nothing special happens, it would be a very nice evidence against the adversary.MaxAug_{May 5, 2007
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According to the abstract, the large amount of DNA is due to polyploidy and polyteny, in other words one chromosome being replicated several times. I can't see that this helps the front-loading hypothesis: the evidence isn't that the bacterium has more genes, only more copies. BobBob O'H_{May 5, 2007
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Isn't a discovery such as this an evidence for evolution? I mean, since some bacteria actually have larger numbers of DNA, then perhaps, all the DNA (genetic information) needed to form the diversity we now have is indeed already present from the get-go (like this kind of bacteria). Just a thought.skwayred_{May 5, 2007
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What's the thinking on the implications of this re: information and Intelligent Design? I often think of information in DNA in a way similar to that of, say, blueprints for a building. It's a crude comparison, I'll grant youÃ¢â‚¬Â¦ but it illustrates how information should relate to complexity. You could say that a storage shed might only require one or two pages of drawings to describe how it's built. And of course, you'd say that a skyscraper's plans would fill up probably hundreds of sheets. You wouldn't expect the storage shed to use more pages than the skyscraper, in other words. In light of that this seems, on the surface, to be opposite of what we would expect to find from a design perspective. I realize that there are other factors, although I don't totally understand them, that pertain to how the information is organized (number of chromosomes, etc.) that might explain it away. But I'm curious what you all think about it. Thanks.TRoutMac_{May 4, 2007
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It also turns out that the lowely coral has more genes than a human. http://www.coralcoe.org.au/news_stories/coralgenes.htmlJehu_{May 4, 2007
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An interesting ID-based research project on such an organism: suppose that evolution has been the result of a front-loaded program that has been working itself out to produce us after a few billion years, beginning with far more DNA than is needed just by it, and this is one of those proto-cells from which everything descended. How about searching the DNA for the coding to proteins etc. needed for eyes, flagella etc.? If you found it, it would be slam-dunk victory for ID.SCheesman_{May 4, 2007
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