The Nature of Mutations

It should be - they've just changed their policy to giving free access for everything from 1996 (I think...) to one year before the current issue. Science | AAAS - registration is free.Edit to correct myself - from September '96 to a year ago. [This message has been edited by Coragyps, 04-25-2003]

I can't really test it to see. We have an institution online subscription so I can automatically access all Science articles that are online including archived materials.Somebody who has no Science subscription please try to access this article...I'm curious if it works...the entire open access business has been controversial.

I thought I'd put in a vote for my favorite definition of mutation so far. My vote's a bit biased because I'm not sure I understood the recombination mutation argument very well.I liked the definition that a mutation is any difference between offspring DNA and parent DNA. Any sequence in the offspring that wasn't in the parent (or one of the parents for sexual reproduction) is a mutation. But are there any significant mutation categories that fall outside this definition?--Percy

I signed up for a free subscription and can't read the full text.

How about restricting the definition to genetic mutations? Epigenetics, etc. could get their own topic at some other point but for the purpose of this thread, any difference between parent and offspring DNA would be a mutation regardless of the mechanism i.e. recombination, improper base excision repair, polymerase error etc etc.

I like that definition too. Of course mutations can take place with any cell division, but for the purposes of the debate the ones we are concerned with are those that are descended with modification from a parent.Incidentally, by my count the score (Message 58) is now:Score: Phospho 0, evolutionists 4FK

Since yesterday some rebuttals from the evolutionist side have been posted. I'll provide another score update when the Creationist responses come in, but for now this is how I have the score. The mere fact of a rebuttal doesn't matter, the rebuttal has to be effective:

• The Milano mutation: Strong and detailed rebuttal from cjhs in Message 66 and by Fedmahn Kassad in Message 59. Point for evolutionists.
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• Culex Pipiens Mosquito: The definitions of mutation proposed so far would decide this point in favor of the evolutionists. Point for evolutionists.
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• RNASE1 AND RNASE1B genes: Solid rebuttal by Fedmahn Kassad in Message 59. Point for evolutionists.
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• Nylon eating bacteria: Solid rebuttal. Point to evolutionists.

Score: Phospho 0, evolutionists 4--Percy

I am not going to extend this thread in another direction than starting a new one but I wanted to re-call to Mammuthus that he holds an interesting position aka whether a hyrid IS ONLY thought in terms of DNA or not. My thought is turning specificlly to question this very notion. I am begining to think from the genetic side of the epigentic-genetic question( which I approach in trying "think up" a process of topobiology (Edelman)) that there may be DNA C H A N G E S that are not mutations in any sense of causality at all and even statistically interms of 3:1 etc may not be in any post-Brad consensus etc etc but rather are the OUTSIDE of the external variable that may be either genetic or epigenetic (or in Lewontin's terminology the computer analogy showing that preformation is not clearly the "loser") but for the momement contrarily I recognize that Mammuthus holds the "standard" position no matter how one is to interpret Muller's ideas FROM the 'position effect'.

What sort of changes would these be Brad?

I was there specifically thinking of whatever it is in the search programs for sequences that prevents easy finding of a match or alignement, i.e. point mutations, junk DNA, non-known expressible repeitions. I am not fluid in DNA base pairing lingo as of yet coming from this more from a whole organ in the ism perspective.I am however trying to imagine if specific expressivity such as to the cell membrane is a flow in one direction from the DNA that these kinds of non-function known changes are FORCED by Newton's Third Law on the the physical chemistry say of having to get beyond any topology of a lipid/water eddy immiscibility that CHANGES when an extracellular protein for instance is expressed and expelled from the cell of "origin". Some epigensis when not "pre-programed" preformation may be involved in motions of this framed by a cell collective kind but not of the line of expression that would have to more than correlationally contiguous in terms of the chemico-physics biophysically etc etc.

Okay, I've mulled it over some more. I think this is a valid criticism of what I was trying to do, actually. I fell into something of the same trap I did by decoupling natural selection from evolution in those interminable discussions with Syamasu. I'll go along with any base pair difference between parent and offspring, excluding somatic changes, being an effective definition of mutation.However, doesn't this lead to calling genetic shuffling during sexual reproduction (not recombination during meiosis I of gametogenesis) - the other main source of variation in a population between generations - a "mutation"?Quetzal the Stubbornly Confused

Dear Brad,Do you intentionally make your posts almost incomprehensible? I'm sorry if it is just that English is not your first language but even so I'm sure you could easily express your thoughts with less pointless jargon i.e. correlationally contiguous.I can't make head nor tail of your sentence on Newton's third law and whatever 'non-function known' changes are.

Ahhhh...try to make it simple and everybody complicates things What the heck..let's say that is a mutation as well.

Upon further thought, I guess we don't want to consider the sum total of the new offspring's genome a mutation though some parents I have met would beg to differ Maybe it should be limited to point mutations for this discussion? Or only include recombination events that produce novelties not present in any form in the parental genomes i.e. a trinucleotide repeat expansion via unequal crossover or additional copies of rDNA genes produced during meiosis...that as opposed to a general meiotic recomination event as you state.Your turn Quetzal...so that I have a chance to make it complicated again

All right, now who's being overly reductionist? I don't agree, even for the purposes of this discussion, that we should limit the definition to point mutations. A lot of the really neat evolutionarily-significant mutations that have been identified are more complex. For instance, the drosophila sperm dynein intermediate chain (Sdic) is a gene that was "born" out of the tandem duplication, subsequent fusion, and then deletion of intervening sequences between two original genes.* Not to mention chimerae like jingwei and sphinx. So point mutation only is right out...I was casting about in desperation for some decent definitions that covered all the bases but was also simple enough to be workable. I stumbled across one that seems to fit the bill with slight modifications (from the Physical and Theoretical Chemistry Laboratory, Oxford University). I think this covers Fedhman's inheritance, my structural mutations, and your epigenetic factors, without begging the sexual recombination question. What do you think?*Reference (PubMed citation):

quote:

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Nature 1998 Dec 10;396(6711):572-5

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Selective sweep of a newly evolved sperm-specific gene in Drosophila.

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Nurminsky DI, Nurminskaya MV, De Aguiar D, Hartl DL.

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The pattern of genetic variation across the genome of Drosophila melanogaster is consistent with the occurrence of frequent 'selective sweeps', in which new favourable mutations become incorporated into the species so quickly that linked alleles can 'hitchhike' and also become fixed. Because of the hitchhiking of linked genes, it is generally difficult to identify the target of any putative selective sweep. Here, however, we identify a new gene in D. melanogaster that codes for a sperm-specific axonemal dynein subunit. The gene has a new testes-specific promoter derived from a protein-coding region in a gene encoding the cell-adhesion protein annexin X (AnnX), and it contains a new protein-coding exon derived from an intron in a gene encoding a cytoplasmic dynein intermediate chain (Cdic). The new transcription unit, designated Sdic (for sperm-specific dynein intermediate chain), has been duplicated about tenfold in a tandem array. Consistent with the selective sweep of this gene, the level of genetic polymorphism near Sdic is unusually low. The discovery of this gene supports other results that point to the rapid molecular evolution of male reproductive functions.

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