3 ms·

Gene expression has nothing to do with altering DNA, leave alone any propagation of such "changes".

by lngnmn 10y ago

danharaj 10y ago
> The study examined DNA methylation—an “annotation” of DNA that alters gene expression without changing the genomic sequence itself—in a group of diverse Latino children. Methylation is one type of “epigenetic mark” that previous research has shown can be either inherited or altered by life experience. What are you even arguing against?
- lngnmn 10y ago
  I am arguing against ignoring the fundamental principle about one-way flow of information DNA->RNA->protein which makes life sustainable. Anything which contradicts with this principle is plainly nonsense - a product of unconstrained imagination. BTW, any changes which could be propagated through the mother's body, the way some deceases do, would not get into the DNA. This is another fundamental principle which contributes to sustainability of life - it is about isolation and washing out of pathogens.
  - maxerickson 10y ago
    Are you rejecting epigenetics entirely then?
  - toufka 10y ago
    See my comment above. DNA can be commented in/out during an organism's lifetime. And these comments/silencing capabilities are in fact transferable to a child with some fidelity. And in that way those changes are heritable and genetic, if not actually altering the DNA of the child in any way. This capability is called epigenetics. You are correct that the code of the DNA itself is not being altered, but there are other heritable mechanisms that affect the structure, capability and accessability of that DNA - i.e. gene expression, beyond the code of DNA itself. This enables capabilities encoded in DNA to be passed down to children without actually using them - or conversely, to enable certain latent capabilities under certain environmental conditions. Life is a bit more nuanced than the dogmatic one-way flow of information we teach as 'the central dogma'. It gains its complexity by always having an exception to its own rules somewhere at some point if it physically possible so, as to hedge against some change in conditions where that exception becomes more powerful than the existing rule. The exception may be inconsequential and of little benefit - until such time as it is not.
    - lngnmn 10y ago
      With generational time of almost 20 years? What you are taking about is an ordinary blood-borne sexually transmitted decease model (or a virus), and it has nothing to do with genetics (gene expression is a developmental topic), so there will be no "marks on a DNA" in principle - it does not work that way. There, however, could be some certain proteins bound to DNA, but it is a not a genetic but biochemical (pathogenic-like) change. Those proteins could be treated as markers. The propagation rate of such proteins is still limited by the generation time, so any connection to cultural differences is nonsense. So, it is not genetic, there is no marks on DNA, it is not cultural. Period.
      - toufka 10y ago
        You are falling into a linguistic trap. The idea of a 'gene' 150 years ago was a "unit of heritable information". We didn't actually know how that information was stored - but we knew it was there (see Mendel's pea pod experiment). In the last 70 years it was elucidated that the primary heritable material was DNA. And so the older term 'gene' became convoluted with a newer concept of DNA. There is currently no good physical definition of a 'gene' - is it the expressed protein, the region required to express the protein, does it include introns, exons, etc? And so other terminology has been adopted. A 'gene' is not just a strand of coding DNA, and technically can include any 'heritable information' - though the primary and most common concept of a gene is a strand of protein-coding DNA, though most biologists would also include the upstream/downstream regulation of that coding sequence in the definition of the gene (promoter, terminator, introns, exons, etc.). The methylation of histones (one type of epigenetic modification) which is a chemical modification of a protein bound to DNA is absolutely a heritable modification, and thus is technically a component of your 'genetic information' - but it itself not DNA. Regardless of terminology, a histone's chemical marks (and biochemical/phenotypic effects) are capable of being transmitted between mother and child, as well as between mother cell and daughter cell. If cell A switches from being heat-sensitive with respect to X, to no longer heat-sensitive with respect to X because a particular promoter was silenced by a histone modification, that phenotype will be passed down to the all of cell A's children (including gametes). That is absolutely a heritable genetic characteristic that has nothing to do with the editing or sequence of DNA. This gets confusing because now our newer definition of gene, which was simplified to be synonymous with coding DNA, actually is more complicated. Finally, gene expression is not just a developmental topic. Gene expression is not only what determines how you develop, but everything else in your body too. Gene expression is how your stomach determines how much enzymes to produce in a given hour, how your white blood cells determine which antibodies to produce in a given season, how your brain determines which neurotransmiters to produce in a given hour, how your skin determines how much pigment to make, how your beta cells determine how much and when to produce insulin, or how your body keeps track of its circadian rhythm, among everything else your body does. Gene expression is one of the primary mechanisms of bioregulation - especially for biological changes that take between a few hours and a few generations. I do not understand your discussion of disease models/virus/pathogens. I'm unclear how those concepts are relevant here. A hypothetical cultural example: A young boy is not well fed and eats a lot of a certain kind of hard-to-digest plant in place of meat. That young boy's own gene regulation may shift towards those enzymes which can break down that plant material and away from genes used to metabolize meat. Further, the entire metabolism may slow because of his cultural environment. It is very reasonable that those regulatory modifications to his own metabolism will be passed to his children. Not changes in the sequence of DNA, but heritable genetic regulation none-the-less. The effects are subtle, and can likely be relatively quickly overcome were the child to experience a significantly different cultural environment.

Gene expression has nothing to do with altering DNA, leave alone any propagation of such "changes".

by lngnmn 10y ago

Gene expression has nothing to do with altering DNA, leave alone any propagation of such "changes".

> The study examined DNA methylation—an “annotation” of DNA that alters gene expression without changing the genomic sequence itself—in a group of diverse Latino children. Methylation is one type of “epigenetic mark” that previous research has shown can be either inherited or altered by life experience. What are you even arguing against?

lngnmn 10y ago
I am arguing against ignoring the fundamental principle about one-way flow of information DNA->RNA->protein which makes life sustainable. Anything which contradicts with this principle is plainly nonsense - a product of unconstrained imagination. BTW, any changes which could be propagated through the mother's body, the way some deceases do, would not get into the DNA. This is another fundamental principle which contributes to sustainability of life - it is about isolation and washing out of pathogens.
- maxerickson 10y ago
  Are you rejecting epigenetics entirely then?
- toufka 10y ago
  See my comment above. DNA can be commented in/out during an organism's lifetime. And these comments/silencing capabilities are in fact transferable to a child with some fidelity. And in that way those changes are heritable and genetic, if not actually altering the DNA of the child in any way. This capability is called epigenetics. You are correct that the code of the DNA itself is not being altered, but there are other heritable mechanisms that affect the structure, capability and accessability of that DNA - i.e. gene expression, beyond the code of DNA itself. This enables capabilities encoded in DNA to be passed down to children without actually using them - or conversely, to enable certain latent capabilities under certain environmental conditions. Life is a bit more nuanced than the dogmatic one-way flow of information we teach as 'the central dogma'. It gains its complexity by always having an exception to its own rules somewhere at some point if it physically possible so, as to hedge against some change in conditions where that exception becomes more powerful than the existing rule. The exception may be inconsequential and of little benefit - until such time as it is not.
  - lngnmn 10y ago
    With generational time of almost 20 years? What you are taking about is an ordinary blood-borne sexually transmitted decease model (or a virus), and it has nothing to do with genetics (gene expression is a developmental topic), so there will be no "marks on a DNA" in principle - it does not work that way. There, however, could be some certain proteins bound to DNA, but it is a not a genetic but biochemical (pathogenic-like) change. Those proteins could be treated as markers. The propagation rate of such proteins is still limited by the generation time, so any connection to cultural differences is nonsense. So, it is not genetic, there is no marks on DNA, it is not cultural. Period.
    - toufka 10y ago
      You are falling into a linguistic trap. The idea of a 'gene' 150 years ago was a "unit of heritable information". We didn't actually know how that information was stored - but we knew it was there (see Mendel's pea pod experiment). In the last 70 years it was elucidated that the primary heritable material was DNA. And so the older term 'gene' became convoluted with a newer concept of DNA. There is currently no good physical definition of a 'gene' - is it the expressed protein, the region required to express the protein, does it include introns, exons, etc? And so other terminology has been adopted. A 'gene' is not just a strand of coding DNA, and technically can include any 'heritable information' - though the primary and most common concept of a gene is a strand of protein-coding DNA, though most biologists would also include the upstream/downstream regulation of that coding sequence in the definition of the gene (promoter, terminator, introns, exons, etc.). The methylation of histones (one type of epigenetic modification) which is a chemical modification of a protein bound to DNA is absolutely a heritable modification, and thus is technically a component of your 'genetic information' - but it itself not DNA. Regardless of terminology, a histone's chemical marks (and biochemical/phenotypic effects) are capable of being transmitted between mother and child, as well as between mother cell and daughter cell. If cell A switches from being heat-sensitive with respect to X, to no longer heat-sensitive with respect to X because a particular promoter was silenced by a histone modification, that phenotype will be passed down to the all of cell A's children (including gametes). That is absolutely a heritable genetic characteristic that has nothing to do with the editing or sequence of DNA. This gets confusing because now our newer definition of gene, which was simplified to be synonymous with coding DNA, actually is more complicated. Finally, gene expression is not just a developmental topic. Gene expression is not only what determines how you develop, but everything else in your body too. Gene expression is how your stomach determines how much enzymes to produce in a given hour, how your white blood cells determine which antibodies to produce in a given season, how your brain determines which neurotransmiters to produce in a given hour, how your skin determines how much pigment to make, how your beta cells determine how much and when to produce insulin, or how your body keeps track of its circadian rhythm, among everything else your body does. Gene expression is one of the primary mechanisms of bioregulation - especially for biological changes that take between a few hours and a few generations. I do not understand your discussion of disease models/virus/pathogens. I'm unclear how those concepts are relevant here. A hypothetical cultural example: A young boy is not well fed and eats a lot of a certain kind of hard-to-digest plant in place of meat. That young boy's own gene regulation may shift towards those enzymes which can break down that plant material and away from genes used to metabolize meat. Further, the entire metabolism may slow because of his cultural environment. It is very reasonable that those regulatory modifications to his own metabolism will be passed to his children. Not changes in the sequence of DNA, but heritable genetic regulation none-the-less. The effects are subtle, and can likely be relatively quickly overcome were the child to experience a significantly different cultural environment.