If you want look up Elowitz M on pubmed, it was in a talk he gave. He was giving a talk on noise in transcription, which is obviously highest when dealing with low copy numbers where stochasticity leads to larger variance in levels. It was obviously an extreme case and I don't know where to track down a reference and finding that kind on info in a lit search is a pain. I know what a half-life is. When you give a steady state level, you need to know the decay rate to make a guess about the production rate. So to comment on how many were made an hour, I had to comment on the decay rate. My primary point is best made in the context of selection. It would require infinite work to get a completely error free process even at the phenotypic level (which would be more buffered). So phenotypic effects will happen at some level due to mutations in mRNA (maybe only partly). I already stated that it wasn't an important point anyways so I don't know why you're being so antagonistic.
I only want to affair my argument that error in mRNA is irrelevant and countered will be cellular recycling and redundancy. I'm sorry if you found me offensive or intimidating.
Perhaps I should say why I asked I asked the question about mRNA. Research seems to provide reasonable, although perhaps not conclusive, evidence for adaptive mutation. It's hard to see how genes could be altered directly except randomly. I wondered if the mRNA transcription process held any possibilities. What's the general view on adaptive mutation these days?
Canute, What kind of adaptive mutations are you talking about? The immune system will commonly shuffle sequences for genes in antibody production, to produce antibodies that are adapted for a specific antigen.
WCfetus, I agree that the mutation rate would be at a low level that is by and large non-consequential. I never meant to say otherwise, but make the point that there were likely to be cases more susceptible to it. I wasn't offended or intimidated, so much as surprised by your repeated posts driven to prove a point I felt I had already conceded. Canute, It would be cool if mutations in mRNAs that improved function could feed back and cause changes in DNA. However the machinery and mechanisms necessary to such a task would be very complicated and potentially problematic. First off the cell would need some measure of function, then a way to differentially measure two proteins, a way to know what mRNA a protein came from ... fairly unlikely. The way things are handled in the immune system are a better model - there is a clear function to select for - lack of auto-reactivity. There is a gene with a primary role in this process that can be mutagenized and selected for. Finally there is a strong need for diversity of this gene. However this if for improving the function of a cell in a certain context - it is quite unclear how an organism could try to select for improvements to itself as a whole. Other than having a variety of children and letting history follow it's course.
Yeah, it does seem unlikely. But what about the research with E Coli and Galapagos finches showing almost immediate genetic response to changes in environment?
Canute, Did you know that if you are emaciated enough your body will start growing extra hair to retain heat? My god that must mean your evolving on demand right? Or how about that when you expose E. Coli to lactose it will produce lactase to lyses and digest the lactose, it's got to be adaptive mutation right? Please Register or Log in to view the hidden image! I'll give you a hint if you need it: look up "operon"
Mutation by environmental demand. I thought that there was something of an argument going on the biology community about it. (Based on the speed with which finches respond to environmental change with changes in beak size). The replies here suggest that it's been settled, but I keep reading stuff that suggests it hasn't.
I don't know if it is settled, but I have a feeling that it could be simple the matter of a theory based on a wrong assumption.
there is actually a debate going on. Evolution suggests that adaptive mutation should not be possible, but there appear to be cases where it is (phenotypically, the genetics of it are still under review). The current theory is that the environmental factors cause already present DNA strands to become active. These DNA strands control the level of mutation correction at the DNA translation level (from DNA to RNA); in other words, when times get tough, the cells allow themselves to mutate more, driving evolution quicker to try and adapt to the environmental change. There is a possibility that something else is going on, but this is the simplest explination that I have read. http://www.sciencedaily.com/releases/2003/10/031024063003.htm
aaaah, give me a case of adaptive mutation and I will explain it. As of yet I don’t understand why it can’t be due to normal evolution or epigenetics.
