They did. What were the controls?
Or in the form of a question to ponder, if we put a sister intestinal cell of the nuclear donor in the dish with the recipient oocyte, will it develop into a frog?
If not, why not?
It would seem to me that “the structure and cytoplasmic contents” would be part of “some given conditions”. Now it’s true that a one-celled zygote has some cytoplasmic contents, but the important ones for development are the various maternal transcripts and proteins deposited in the egg, and those trace back directly to maternal DNA. Any maternal cytoplasm is so diluted after a few cell generations that it would seem unable to be important in later development.
But more importantly, we’re talking about evolution here, and none of this cytoplasmic inheritance is stable or dependable enough to be relevant to the differences between species. Evolution is all about genomes, and phenotypes, etc., affect evolution only to the extent that they have genetic bases.
Sort of. Individuals of most species inherit their locations from their parent. But is this significant information? Is it evolutionarily important?
I don’t know what all “creationists” say, but Jonathan Wells has often made the point that DNA alone does not determine developmental outcomes; the organismal environment in which the zygote develops also plays a role. He certainly doesn’t believe that things are as simple as reading off the DNA sequence, and presto!, the new organism appears. For him, there is much environmental information that interacts with the DNA information to produce the overall result. I heard him say this at a talk at a conference, and I’ve seen him say it in print as well, though I can’t summon any articles to mind at the moment. If Paul Nelson @pnelson is listening in on this discussion, he probably could tell us where Jonathan (and others) have said similar things.
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If Jonathan Wells’ ideas on this were correct, no one could ever have regenerated normal, fertile plants from isolated protoplasts. This example and other cell fusion experiments in plants pretty clearly refute Wells’ notions.
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I think that there are too many direct evidences of plants and animals inheriting non genetic information, for anyone to sustain the claim that only genetic information is inherited. For example some lizards have a plastic physiological response to their diet, which can alter the shape of their head, teeth, and digestive tract simply by changing their diet.
https://www.jstor.org/stable/10.1086/651704?casa_token=fxtwgHkpAZUAAAAA%3AFY0E0FH9NTWT39KrAPQRuqTUEf54gPVpAn2JLpVGZUmrx_NESpl0psBKkDDyj6Grh3ivi_8HSSGqCvxwaKuW2I8cBfiBAhnhWh5WyZlLCEitqEfXSI0&seq=1
It is also true that some species of reptiles, amphibians and fish have their sex determined by the ambient temperature. In the case of lizards this happens both with species that have established genetic sex differentiation and those that don’t.
So while genetic inheritance is extremely important, I think that the natural world is full of examples that other factors are important as well.
I agree with this, but it is still irrelevant to my point. More so, I am only talking about heritable information which can be passed down through generations of progeny, not the entire information present in cells. DNA is the only molecule that serves that function.
Is there heritable information which is passed down through generations of offspring? No.
I disagree. Again show me data that demonstrates your claim which is that something other than DNA can store and transmit biological information needed to build organisms?
Humans can make globins. Is the information needed to make those globins stored anywhere else other than DNA? Can the information needed to make globins be passed on to progeny without the agency of DNA?
If you still feel confident in the claim that biological systems asides DNA store and transmit heritable information, by all means show me the data.
It doesn’t matter what controls they used, because they had DNA as well. The study is of no relevance to our discourse.
Therein lies the misunderstanding. The actual development of organisms depends on DNA and the environment that DNA molecule is kept within. The information itself is solely kept in DNA, and transmitted only through it during cell division or any other process. This is basic biology.
When a cell divides, its daughter cells gets a fraction of its cytoplasm and membrane constituents. This fraction holds information needed to utilize the organism-building information contained in DNA. That’s it.
None of you have been able to provide any sort of data that shows heritable information needed to build organisms can persevere and transmit through anything other than DNA.
You’re contradicting yourself now, and you seem to have conceded the point.
This question of whether the the information perseveres indefinitely unaltered from generation to generation is irrelevant. It is information and is necessary to construct the daughter cells, and for the functions of the cells. The information in DNA also changes over time, just much more slowly. No replicative process known is perfect(which is why evolution is not only possible, but inevitable).
The compositional information is of course relatively stably inherited simply by division. If you divide the contents of a cell in two, both halves retain the same relative proportions of contents. Compositional information is retained, even if you divide them unequally (30:70 by volume, for example). They still do if you do it again. While you end up with a smaller total volume, the compositional information of that fraction is still retained. And you can keep doing this until you are down to individual molecules, at which point the information is then lost if you keep going.
Now what actually happens is that cells go back to growing after cell division, synthesizing new constituents to fill the volume of the cell. When this occurs, the previous generation’s contents are diluted in the newly synthesized contents, and so the compositional information is gradually lost more quickly with each passing generation until eventually after a few generations it’s completely gone. That doesn’t mean it wasn’t information, nor does it mean it didn’t contribute causally to the construction and functions of the cell when it was present.
In terms of the relative contributions I would definitely agree that DNA holds vastly more information than the remaining parts of the cells, which we can see if we imagine losing a large fraction of the cytoplasmic contents, the cell, as long as there are still a few remaining of the necessary regulatory proteins, transcription factors(RNA polymerase) and transcripts, and still-active ribosomes (and the cell-membrane remains intact to prevent loss of homeostasis), can then effectively be regenerated. The DNA is necessary to accomplish this, and basically everything can be re-created with a small remainder of the cellular contents plus the DNA.
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No and no.
I am really surprised you can’t get my simple point. The information needed to make every RNA and protein molecule (which in turn direct the synthesis of other constituents) within a cell or organism is found only in DNA. This is true whether or not that DNA molecule is right there in the organism or in a test tube in Lenski’s lab.
The cytoplasmic contents gotten by daughter cells only have information (like particular ligands they bind to initiate or repress a signalling cascade) needed to utilize information contained in DNA. That’s why we can comfortably express certain human genes in yeast or E .coli using the native biosynthetic machinery in those organisms.
That’s why I kept on saying you were strawmanning me. It is this information that I have been harping on since, the type only DNA stores and transmits across generations. The type of information DNA stores is specific and will only produce the organism it came from, unless altered significantly. Non-DNA components don’t carry such information.
It is information needed to construct anything, by reading DNA. The information in DNA can only be used to construct particular things (and that’s what I mean by heritable information). The information in DNA is akin to the blueprint of a house, while the information held by the mason (proteins and RNA) can be used to actualize any blueprint.
Yes, there is compositional information, but the one DNA holds is a template or guide for the construction of entire organisms, while the information held by non-DNA components allows them to control when, where and how much DNA information is utilized.
All excerpts are from Molecular Biology of the Cell, sixth edition, page 369 (emphases mine) and they aptly state what I have been saying in this thread since it began.
If hereditary information was present in something other than DNA, then these excerpts don’t make sense.
They had the same DNA, thus it is very relevant.
And that environment provides information. Not all information is digital.
And some of that essential information is inherited but not encoded in DNA.
It does. It does not, however, encode all of the information required to construct a new organism. You’re conflating nucleic acids with information.
I think we would all agree that phenotypic plasticity has its role, but it isn’t powerful enough to explain the differences between species. It isn’t as if you can put humans in the same jungle as chimps and have humans suddenly giving birth to chimps.
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Well, for example, culture is heritable. And it is encoded in biological societies and cultural artifacts, not DNA.
Globin genes are stored in GenBank, and humanity bequeaths this information, the information to make globin genes of far more sorts than we see in human genomes, to the progeny of all humankind. This information is stored in silicon, not DNA.
So yes, I am very confident that there is heritable information of many sorts stored outside of DNA.
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I believe you have lost sight of the topic, which is, or at least used to be, evolution. What causes the differences among species? What is inherited that results in these differences?
This thread is weird. If we are talking about the context of a few thousand generations, the only relevant factor of heredity is the genome. At the same time, it is obviously wrong to same that only the information of the genome is needed for organisms to develop. It is my impression that @Michael_Okoko and @John_Harshman are trying to discuss the former scale, while @Rumraket and @Mercer are talking about the latter. And @swamidass is, I ‘think’, talking about cultural transmission?
This confusion is understandable, given the somewhat confused way that Davies approaches biology. Which is to say: by making a bunch of technically correct but extremely overstated points and then connecting them with hot air and nonsense. Anyway, if we could agree on the scale under discussion, that might be helpful.
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Some of those inherited differences (certainly not all) can be caused in part or even completely by cultural or environmental inheritance, independent of DNA.
Yes, that’s right, and other types of inheritance like cultural inheritance.
The DNA-only view is obviously overly simplistic. And this has nothing to do with time scales. It has more to do with categories.
Could you name a couple?
I think it works fine for the evolution of nearly all life, for nearly the entire history of life. Certainly not sufficient for humans, and possibly insufficient for a few dozen other metazoans, but it is ‘generally’ fine. Obviously, that is for long-term inheritance, DNA-only is obviously overly simplistic for almost any life at the scale of a few generations. But that isn’t for ‘cultural’ reasons, so…
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This. I am trying to address the claim that information only resides or exists in the genome of an organism, which it does not. I am not trying to address the magnitude of influence this non-genetic information might have on evolutionary timescales.
I do not think that agreeing that there is heritable non-genetic information in cellular structures and compositions in any way undermines or contradicts the primacy of genetic changes in understanding long-term evolutionary change.
Paul Davies is known to say a lot of either trivial or misleading technobabble, but in this particular instance the quote of him that was originally objected to did not contain any of these transgressions that I can see.
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That’s why its irrelevant. The DNA they possessed had all the information needed to enable their development into mature frog, while the peculiar egg cell environments had the necessary cues to spur this development. This has been my position all along.
The environment in question basically consists of RNA and proteins, all of whose biosynthetic information is stored in DNA.
What is hereditary information?
Yes it does and Molecular Biology of the Cell agrees with me.