Basically, some scientists altered a gene on a strain of bacteria essentially at random in order to see if this could result in beneficial effects. Suprise suprise, it did. In fact, with only two amino acid changes (that could be as few as two changes in DNA "letters", and at most six) a gene that normally inhibits a certain functionality enabled it.
For some perspective, spontaneous single base changes are relatively common; there are numerous diseases/syndromes that are caused by the occurence.
Just to reiterate -- scientists, by causing random changes of a sort regularly and abundantly found in nature (but at a much slower pace) have caused one gene in the bacteria to become a new, completely different gene (which coincidentally has almost the exact opposite function) and enabled bacteria which would otherwise die to survive.
Posts: 15770 | Registered: Dec 2001
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Um, this really isn't that big a deal (at least not in the way it's being reported).
This is just mutagenesis and selection. This is the way most bacterial genetics has been done for...well, I don't know exactly how long, but it must be decades. As long as there has been such a field as bacterial gentics.
You randomly mutagenize the bugs, then you look for the phenotype you are interested in. Often that phenotype is the ability to survive under certain circumstances, because that makes the selection of mutants easy, but you can screen for other things as well. Then, once you have a mutant you analyze it to see what gene you hit and what the change was. This is so simple and routine that first year grad students (like me) do it for short research rotation projects.
Now what IS sort of interesting is the exact way in which the bacteria changed (the iron-sulfur bridges). And that's the way you hope it works with mutagenesis. The actual changes in your mutant are revealing or important (or you hope so anyway) but the fact that you can find a mutant that can survive in practically any conditions you care to select for is well established. In fact, the main reason you do the experiment is because you believe you will be able to find the mutant you want. It's the opposite of surprising, it's a really basic and reliable technique.
So I guess what I'm saying is, these people have done some very good science, but it's being reported in a totally lame way that misses the point of the result. This doesn't say anything about evolution that we didn't already know. But it does say something about disulfide bond formation and protein folding.
Posts: 96 | Registered: Jun 2001
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Oh believe me, I'm very aware of how we've been doing things like this for a while. However, this is the first time I've run into a particular combination -- a good write up of the description for people less well versed in biology to understand, and a result that's very clear as to what happened -- we know exactly what changes happened, and that they had not been there before, and that they were of a sort that regularly happens "in the wild" (so its not really possible to mount the "but this only happens in the lab" attack).
As such, I felt it quite worthwhile to point it out.
(I'm very well aware that splicing new genes into bacteria is old news in particular -- I did it in AP biology, after all).
Posts: 15770 | Registered: Dec 2001
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