Izawwlgood wrote:
aph wrote:OK. Here it is again:
http://www.ncbi.nlm.nih.gov/pubmed/23224554
Important parts in bold:
And as I told you last time we went over this exact paper, everything you linked here is discussion stress response and/or double strand break repair, and how this results in increased rates of mutagenesis. I absolutely agree, and am well aware of the fact that in times of stress, stress response factors/pathways are activated, and that some of these response pathways result in enhanced rates of mutagenesis.
None of this implies that E.coli 'control their rates of mutagenesis'. None of this implies directed evolution. None of this implies 'feedback loops reduce 'stress molecules''. In fact, at this point I'm almost confused what you think this paper is implying. Can you specifically and clearly state in your own words what you think this paper is saying, and how it relates to your idea?
Sure. I never said that E.Coli can control its rate of mutagenesis. Though, the papers explicitly state that mutagenesis is a highly regulated response (as opposed to being random), my use of the words control and regulate, common in my area of science no one seems to know about, means that what is attempted to be maintained at a certain reference level is an input to a feedback loop. That is why I'm saying that what is being controlled by means of mutagenesis is the level of "stress molecules". I'm saying they are an input to a feedback loop.
I've learned that "directed evolution" actually has a very clear definition in this context, and means that certain locations in the genome are targeted during mutagenesis, I'm not proposing this is happening with E.Coli, though there are some papers evidencing research on the phenomenon of at lest partial directednes.
aph wrote:Note the use of expression "accelerated evolution". You said I shouldn't use "slowed evolution". Why would that be?
Say mutagenesis occurs at rate x. During one type of stress response, mutagenesis occurs at rate 1.1x. This means that that stress response is resulting 'accelerated evolution', sort of (increased rates of mutation != evolution if you don't have selection), but normal activity isn't 'slowed evolution'. It's 'normal evolution'. Slowed evolution would be a response that results in lower rates of mutagenesis and/or variation. None of that is going on.
Well, if something is accelerated, and then decelerated, I'd say it slowed down. I understand it doesn't mean it completely stopped.
I think the problem is that you assume 'stress response = conscious effort to reduce stress'. It is not. Can you show me specifically where a researcher says 'mutating to relieve stress' or 'to relieve selective pressures'? I'm not seeing that in the paper you linked.
Of course not, I don't suppose any conscious efforts.
And yes,
https://www.google.hr/search?sourceid=c ... e%20stress
https://www.google.hr/search?num=20&esp ... FY_-A3dDIU
It'd be like if I decided 'feedback loop' really mean 'has oral sex with', and used a comp. sci paper on feedback loops as proof that computer scientists were sex addicts.
Well, in my area of science, presented in the thread next by, "feedback control" means a very specific thing, it has meant that very specific thing since about 1960. I've been trying to present what it means on this thread too.
Sure, might seem peculiar, but it's very specific and defined, also used in some other areas of science and sometimes in common language.
Statistics: Posted by aph — Mon Jan 05, 2015 3:04 am UTC