Intelligent Design

Which came first – butterfly or caterpillar?

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One of my favorite sources for “just so” stories in organic evolution is metamorphosis. Consider: when a caterpillar matures and forms a chrysalis, the caterpillar’s body almost completely dissolves into a yellow mush which then serves as a source for raw materials to reform into a butterfly. I wonder how that scenario came about through mutation and selection. How would destroying almost the entire body and reforming into something that, by morphology alone would be a very different species, come about by Darwinian gradualism? Where’s the selection value in a partially decomposed body? Surely the process could not have evolved in one fell swoop. What series of gradual transitions make sense in light of chance & necessity?

41 Replies to “Which came first – butterfly or caterpillar?

  1. 1
    bFast says:

    It is my understanding that metomorphosis is one of the great puzzles of biology. I recently read a blerp on either livescience.com or PhysOrg.com that suggested that metomorphosis was some sort of amalgamation of two separate organisms. That said, it seemed terribly speculative to me — like the guys recognized that they were only speculating.

  2. 2
    jerry says:

    Does anyone know of any good sources on development? Like the caterpillar to butterfly, nearly every multi-cellular organism changes form after gestation. What controls these changes. It cannot be the egg as this is long gone but something in nearly every organism controls the expression of genes over time.

    As humans we see this in growth and maturity especially in adolescence. Where in the body is the control for these processes? Anyone have any good sources or is it a mystery?

  3. 3
    hrun0815 says:

    bFast, I doubt that many biologist share the view of metamorphosis being an amalgamation of two separate organisms. It would be truly remarkable if the fruitfly, THE model organism for genetic studies (and on of the earliest fully sequenced multicellular organisms) had a mashup of two genomes without anybody actually finding any evidence for it.

    There are indeed speculations about metamorphosis in insects. For a good (albeit somewhat dated) review on competing hypothoses:

    http://www.nature.com/nature/j.....447a0.html

    As to the answer to DaveScot’s question, I guess there are two, depending on what meaning the question is supposed to have.

    Literally, the answer is neither: Butterflies and caterpillars are the same species and thus appeared at the same time. However, if it is not meant literally, then the butterfly appeared first.

    The earliest insect showed direct development (ametabolous). Only later insects, the Holometabola exhibit the different larval, pupal and adult stages we find in butterflies. So the butterfly (or fully differentiated insects) came before the complex metamorphosis of the Holometabola.

    As for gradualism, it might be interesting to study the hemimetabolous groups of insects that fall in complexity of metamorphosis between the ametabolous and holometabolous groups.

    Jerry, if you are interested in insect development, I would suggest you start looking at Drosohpila development first. It has been used as a model organism (in particular for developmental studies) for so long, that a tremendous wealth of information is available.

  4. 4
    Cloud of Unknowing says:

    jerry,

    “As humans we see this in growth and maturity especially in adolescence. Where in the body is the control for these processes? Anyone have any good sources or is it a mystery?”

    Certainly development is genetically directed, but there is nothing like a blueprint of the adult encoded in the DNA. And there is certainly no centralized control. A biologist once told me that he marveled at people’s arms growing to the same length.

  5. 5
    Cloud of Unknowing says:

    “metomorphosis was some sort of amalgamation of two separate organisms”

    The hypothesis is that metamorphosis results from hybridization of two species. Darwin dismissed hybrid evolution, but there is now considerable evidence that it is more important than long believed. The notion that the “tree of life” is actually a network seems to be catching on with scientists.

  6. 6
    Gerry Rzeppa says:

    So how do you think the butterfly/caterpillar thing came to be, Dave?

  7. 7
    Shazard says:

    Gerrym Rzeppa,

    it’s Eazy… This small larva went to sleep during winter… soon it developed it’s cocon as good warm house… But suddenly during sleep cosmic rays, bla bla bla… all that recombined larvas body into butterfly…
    Pure chance and NS 🙂
    NS in this case is… larvas which could fly was better suited for survival…

  8. 8
    DaveScot says:

    Cloud of Unknowing

    Actually the development program appears to be outside the DNA. In experiments where an enucleated egg from one species has a nucleus from another species inserted into it development proceeds along the path of the egg’s species not of the nucleus’ species until incompatibilities between the egg and the nucleus cause a spontaneous abortion except in very closely related species. DNA appears to be a collection of building blocks where the majority of blocks are common to many species and few are unique to just one species.

    What is actually going to be built by the development process appears to be controlled by a program outside the nucleus. The following is a recent experiment where a carp nucleus was inserted into a goldfish egg (carp and goldfish are very closely related). Development proceeded along the lines of the goldfish, not the carp.

    http://www.bioone.org/perlserv.....104.031302

    As a systems design engineer I’ve consistently been of the opinion that the 1 gigabyte information carrying capacity of the human genome is grossly inadequate to contain the component specifications and assembly procedure required to build a human body. If a significant amount of that DNA is junk then it only exacerbates the problem. Clearly though, the specifications and assembly procedure are contained within the cell wall of the egg. The rest of the egg consists of trillions of atoms more or less precisely arranged. The potential information carrying capacity of those trillions of atoms is orders of magnitude greater than the nuclear contents. Thus I believe the larger information repository is outside the nucleus. This is studied under the rubric “epigenetics”. A horse is a horse and not a fly not because of its DNA but because its mother was a horse. We really don’t know any more than that at this point. Geneticist Giuseppe Sermonti wrote a book on the question titled Why is a Fly not a Horse? which may be of interest to you.

    In computer hardware and software design, which is my area of professional expertise, we have an analogous design methodology where we have common component libraries that are shared between programs that are very different in how and what they actually do. Often, in order to save space, we cull those libraries to the components that are actually used by the program. What the program actually does is dependent not on the library but on how the components are called upon and is external to the library itself. I’m very interested in Craig Venter’s work at assembling a global gene library from tens of thousands of different microorganisms he is shotgun sequencing from samples obtained from the ocean depths in a circumnavigational cruise. This may represent an uber library of all the component parts used in all forms of life sans culling for individual species. My experience has been that many if not most aspects in the design of life have analogous design methodologies independently discovered and employed by human engineers.

  9. 9
    DaveScot says:

    Gerry

    So how do you think the butterfly/caterpillar thing came to be, Dave?

    The same way humans design complex systems. Both the larva and the butterfly were preconceived in the mind of an intelligent agent who then turned abstract thought into physical reality. I think that’s the best explanation at the current time although it may be proven incorrect in the future. That’s just the nature of science. The best laid plans of mice and men often go astray. ~Robert Burns (misquoted for clarity in modern english)

  10. 10
    Joseph says:

    Once the pupa or chrysalis stage is reached, the caterpillar starts emptying itself; its organs dissolve, and its outer covering is shed. Only certain groups of cells, called imaginal disks, remain vital. From these develop all the structures of the adult…

    Caterpillar and butterfly are widely differing forms, the one not derived from the other but both from totipotent embryo cells, some of which the caterpillar retains in its body so that they will in due course destroy it and replace it with another.”–geneticist Giuseppe Sermonti pg 103 “Why is a Fly Not a Horse?”

    Got that? The caterpillar does NOT develop into a buttterfly. It dissolves and becomes food for the next body.

  11. 11

    Here is one on the design-by-contract model :

    “In modelling on design-by-contract, evolution is seen as a continuously expanding system of functional modules which are separated by conserved interfaces. A scenario in which the larval stages were developed before the adult body plan, is relatively simple since it will keep existing developmental interfaces intact. It is therefore proposed that the larval stage of holometabolous insects reflect the reintroduction of an ancient, existing body plan and therefore represents an atavism.”

    Origin of insect metamorphosis based on design-by-contract: larval stages as an atavism

    Enjoy!

  12. 12
    Gerry Rzeppa says:

    “A horse is a horse and not a fly not because of its DNA but because its mother was a horse.” – Dave Scot

    So the rabbis were right all along: a Jew really is “someone born to a Jewish mother”!

    Both the larva and the butterfly were preconceived in the mind of an intelligent agent who then turned abstract thought into physical reality.” – Dave Scot

    I agree. But I’m curious, really. Your profile here says you’re a “convinced agnostic”. Now since you’re clearly able to recognize design when you see it, and since I assume you don’t consider an infinite regress of intelligent designers a reasonable proposition, why doesn’t your logic lead you to the existence of a necessary, eternal, First Cause? Where do you get stuck?

  13. 13
    DaveScot says:

    gerry

    “Where do you get stuck?”

    I get stuck where the evidence stops. The design can be examined. The designer can’t be. At least not yet.

  14. 14
    Cloud of Unknowing says:

    Gerry: “why doesn’t your logic lead you to the existence of a necessary, eternal, First Cause?”

    Why must a First Cause be eternal rather than self-immolating in an original act of creation? May a Creator not enter fully into transient existence of its own creation? That is, may a Creator not die in order to live?

    The value of logic is ultimately aesthetic. The phrase “life eternal” is absurd, yet I would never sneer at people who

    Existence-without-ground is an abomination to me. Though I cannot prove it, my continual participation in creation is an ineluctable aspect of my experience. I certainly have no basis for relegating creation to the past. The Creator may recreate continually. Then again, I cannot say certainly that my perception of creation in the present is not an illusion engendered by a First and Final Cause.

    It seems that the prevailing opinion at Uncommon Descent is that uncertainties intrinsic in human experience can be dispatched through reason or common sense. Mathematics itself has shown that what we may establish through logic is quite limited. And I have observed that good sense is not common.

  15. 15
    Cloud of Unknowing says:

    Oops. That was an incomplete comment. The touch pad on my laptop is acting up today.

    I was in the process of editing to say that logic is also of pragmatic value. I would never sneer at people who use the illogical phrase “life eternal” to refer to an article of faith.

    I was going to end by saying that the intrinsic ambiguities of what people can know are not dispatched by reason or by common sense, but by faith. There is a great deal I do not know, but I do know that it is wrong to say that that it is obviously right to trust empirical data and logical interpretations thereof. I find the statement “the Designer meant for us to understand existence by doing science” terribly naive.

  16. 16
    bFast says:

    ghghghjgygygygygygguiuybyyffiuiiiuiiuiuouui-i98888j7uj77uj8ju8ju8jju8u8u8u8u8u8u8u8u8u88uujj8uj8juu8uu

  17. 17
    Cloud of Unknowing says:

    DaveScot,

    I do not understand your focus on the cell wall. For instance, mitochondria play an essential role in cellular differentiation. A key observation in the interesting study you pointed me to is that the donor’s mitochondria slowly disappear.

    Turning to humans, I am sure that development involves much more than information within the embryo. The mother changes in response to the developing embryo, and development is in part controlled by the environment supplied by the mother. Think, in particular, of how the mother changes hormonally during gestation, and how having the right hormones in the womb at the right times is essential to development. I’m no Norbert Wiener, but I see two systems regulating one another with feedback. In vitro gestation of a human would require an artificial womb, and I suspect that it would be very difficult to engineer one.

  18. 18
    Daniel King says:

    bFast #16

    ghghghjgygygygygygguiuybyyffiuiiiuiiuiuouui-i98888j7uj77uj8ju8ju8jju8u8u8u8u8u8u8u8u8u88uujj8uj8juu8uu

    Well said!

  19. 19
    bFast says:

    I believe that ghghghjgygygygygygguiuybyyffiuiiiuiiuiuouui-i98888j7uj77uj8ju8ju8jju8u8u8u8u8u8u8u8u8u88uujj8uj8juu8uu was the product of my 4 year old daughter playing on my computer. Sorry.

  20. 20
    bFast says:

    Daniel King:

    bFast #16

    ghghghjgygygygygygguiuybyyffiuiiiuiiuiuouui-i98888j7uj77uj8ju8ju8jju8u8u8u8u8u8u8u8u8u88uujj8uj8juu8uu

    Well said!

    Hey, if this was profound, we may have just validated profundity from a random event!

  21. 21
    Gerry Rzeppa says:

    Dave Scot –

    Believe it or not, that helps me a lot. Thanks.

  22. 22
    Gerry Rzeppa says:

    “Why must a First Cause be eternal rather than self-immolating in an original act of creation? May a Creator not enter fully into transient existence of its own creation? That is, may a Creator not die in order to live?” – Cloud of Unknowing

    It’s very difficult to argue such big things in a little box, with a stranger, where the common ground to which one might appeal is unknown. But so you know I’m not simply ignoring your questions…

    1. It seems to me that “a creator who immolates himself in an original act of creation” had to be somewhere or something before he immolated himself. And so it seems, at least to me, that you haven’t reached back far enough. But such talk is probably meaningless since the “time” we know was probably just one aspect of that initial creative act.

    2. As for “a creator entering fully into the transient existence of his own creation”: this seems like a step down to me, especially since I’ve seen nothing in the whole of the physical universe that isn’t topped by the tiny “universes” in our puny little heads. After all, it is you and I who are talking back and forth about this; if the universe is aware, it’s not much of a conversationalist.

    3. As a Christian, I believe in the merits of sacrifice and redemption; I believe, as an article of the Christian faith, that our Creator did indeed “die in order [that we may] live”. But He died as a man, and had to first subsume that identity to make that death possible.

    All very mysterious, of course. But a man has to drop his anchor somewhere if he is adverse to aimless drifting (in a Cloud of Unknowing!) and wants at least enough stability to get some things done…

    “The heaven, even the heavens, are the Lord’s: but the earth hath he given to the children of men.” – Psalm 115:16

  23. 23
    Cloud of Unknowing says:

    bFast,

    I thought it was zen.

  24. 24
    magnan says:

    DaveScot (#8): “Actually the development program appears to be outside the DNA. In experiments where an enucleated egg from one species has a nucleus from another species inserted into it development proceeds along the path of the egg’s species not of the nucleus’ species ”

    This is fascinating and does appear to show what you say. However, I think there could be another explanation. The cytoplasm and extranuclear organelles in the original egg cell seem to contain a complex of developmental information in some form. This developmental specification data could have been previously derived from the egg’s own original nuclear DNA. Of course for this to be credible it would also have to utilize most of the so-called junk DNA.

    Another thought on this. If the developmental program always resides in some non-DNA form in the cytoplasm and/or extranuclear organelles, how is this information replicated in new sex cells? I thought most of the cytoplasmic structures, organelles, etc. are replicated from DNA information in the nucleus.

    Also, if it is non-nuclear and non-DNA, how does it appear to follow Mendelian laws implying gene units, etc.?

  25. 25
    Cloud of Unknowing says:

    Gerry,

    You spoke of where Dave’s logic might lead him. My response, boiled down, is that logic leads to all sorts of questions without logical answers. If you reread my post, you’ll see that I begin by suggesting that creation occurred in the past, but then turn immediately to the notion that creation is continual. There is no logical basis for choosing one alternative over the other. Some people make a choice on the basis of faith, and then adduce “logic” to the choice after the fact. I prefer to remain mindful of my ignorance, and draw only a few conclusions on matters of ultimate concern.

    All very mysterious, of course. But a man has to drop his anchor somewhere if he is adverse to aimless drifting (in a Cloud of Unknowing!) and wants at least enough stability to get some things done…

    “The heaven, even the heavens, are the Lord’s: but the earth hath he given to the children of men.” – Psalm 115:16

    Science is play. I hope to cut loose the anchor and abandon all pretense of importance in what I do.

    “Truly I say to you, unless you change and become like little children, you will never enter the kingdom of heaven.” — Matt 18:3

  26. 26
    Gerry Rzeppa says:

    Cloud of Unknowing –

    Okay, I see where you’re coming from. And I’m also a great believer in childlike wonder, curiosity, joy, trust, submission, etc. But that’s not the only precept in the Bible, y’know.

    Perhaps I can sum the matter up. It is true that:

    “…unless you become like little children, you will never enter the kingdom of heaven.” — Matt 18:3

    And it is also true that:

    “God blessed them, and said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.” – Genesis 1:26

    And therefore it seems that:

    “To every thing there is a season, and a time to every purpose under the heaven.” – Ecclesiastes 3:1

    A time to be children at play; and a time to be grown-ups at work (without losing our childlike wonder, curiosity, joy, trust, submission, etc).

    Yes?

  27. 27
    Cloud of Unknowing says:

    Gerry,

    “I’ve seen nothing in the whole of the physical universe that isn’t topped by the tiny “universes” in our puny little heads. After all, it is you and I who are talking back and forth about this; if the universe is aware, it’s not much of a conversationalist.”

    Back in 1974, an MIT doctoral student and his advisor investigated the problem of deciding the truth of sentences in the weak monadic second-order theory of one successor. (This is a hamstrung, but interesting, logic in which all sentences can be decided true or false. Godel does not rear his ugly head.) They proved that a logical device known as a Boolean circuit would require at least 10^125 logical elements (gates) to process sentences of length up to 610. The number 10^125 is their estimate of how many protons could be packed into the space occupied by the known universe. (Stockmeyer and Meyer, “Cosmological Lower Bound on the Circuit Complexity of a Small Problem in Logic,” Journal of the ACM, 2002.)

    An interesting question is whether some human can prove true or false more than half of randomly generated, syntactically well-formed sentences of length somewhat greater than 614. (The increased length bound comes from the shift to probabilistic computation. See the paper.) ID advocates could put the hypothesis that human intelligence can outperform materialistic computation to empirical test. There’s certainly enough brain power around, and a positive result would create a sensation.

  28. 28
    Cloud of Unknowing says:

    Gerry: “Yes?”

    “When hearts are high the time will fly so whistle while you work” — Alan Turing as Snow White

  29. 29
    magnan says:

    Cloud of Unknowing (I like your monicker), could you explain what you mean by “decide the truth” in the MIT study you mentioned? You imply that “deciding the truth” of sentences is equivalent to proving their truth.

    This doesn’t seem relevant to human use of language for communication. With human language, the task is to derive the meaning of the sentence, regardless of its truth, given possible ambiguities and nonsense words. The meaning is derived from the syntax and semantics, context, and finding associations and correlations with a vast body of external information.

  30. 30
    DaveScot says:

    magnan

    In most cell divisions the cytoplasm is simply divided in two and equally distributed to the two daughter cells. A notable exception, perhaps relevant here, is in the production of an ovum where one daughter gets all the cytoplasm and the other dies for lack of it.

    New organelles to replenish the halving during cell division are indeed generated from information in DNA but the question still remains whether the preexisting organelles influence that process.

    That said I’d look to the structure of the cytoskeleton rather than the organelles as the larger repository of epigenetic information.

    In any case the experiment makes clear that the protein and (probably) RNA structures outside the nucleus play at least some role in the developmental program. And that of course runs us headlong into my favorite chicken/egg paradox – which came first: DNA or protein?

  31. 31
    Cloud of Unknowing says:

    magnan,

    [Apologies first to DaveScot for going off-topic again.]

    The norm in logic is that any sentence (formula) that is grammatical (well formed) has an unambiguous semantic interpretation. This is quite different from natural language, where a grammatical sentence (e.g., “Colorless green ideas sleep furiously.”) may be meaningless.

    In formal language theory, a language is simply a set of strings (sentences) over some set of symbols (alphabet). For instance,

    {0, 11, 011, 1001}

    is a language over the alphabet {0, 1}. A language may contain infinitely many sentences.

    There are languages L with the property that no computational method we know of can decide whether an arbitrary sentence is an element of L. This holds even when the method is given infinite memory to work with.

    We may regard the set of all true sentences in the logical theory I alluded to above as a language. Deciding whether a sentence is an element of the language is equivalent to proving it true or false. It has been established that that membership of a sentence in the language is computationally decidable. But Stockmeyer and Meyer show that even when the language is restricted to short sentences, the decision process requires computational resources that are not only out of this world, but out of this universe.

    Fun fact to know and tell: While Stockmeyer and Meyer did not publish their result in a journal until 2002, Frederik Pohl used it in his 1980 scifi novel Beyond the Blue Event Horizon to explain why a computer of the future could not answer every question put to it. Present-day deductive database systems either restrict the form of logical sentences in the database or give up trying answer a query when “too much” time elapses.

  32. 32
    Cloud of Unknowing says:

    DaveScot: “And that of course runs us headlong into my favorite chicken/egg paradox – which came first: DNA or protein?”

    Any less-than-omniscient designer of life would have to begin with minimalist prototypes. Gerald Joyce obtained through GUIDED molecular evolution a population of reproducing DNA (RNA?) molecules that required only one intervention to go from generation to generation. This is a strong hint that a first prototype of a self-sustaining population of self- replicating individuals would comprise a collection of DNA or RNA molecules, perhaps configured by some means more clever than guided evolution. Why start with a proteome when DNA and RNA molecules are themselves capable of so much? Of course, the designer may have been an omniscient Creator of cells — we don’t know.

    The evodevo people know more about fly eggs than chicken eggs. There is a well known maternal effect gene in Drosophila, bicoid. The nurse cells of the egg-producing follicle, not the embryo, synthesize the bicoid gene product and deposit it in the part of egg that will be the front end of the offspring fly. Only one end of the egg is in contact with nurse cells, so this works out simply, provided the mother is not a mutant without the bicoid gene. The bottom line is that major aspects of the body plan are not under genetic control of the offspring, but a gene in the mother, along with the structure of the follicle (genetically determined?), does cause molecules essential to differentiation to be differentially distributed in the egg.

    I’m more impressed by the follicle/egg paradox than the DNA/protein paradox.

  33. 33
    hrun0815 says:

    In most cell divisions the cytoplasm is simply divided in two and equally distributed to the two daughter cells. A notable exception, perhaps relevant here, is in the production of an ovum where one daughter gets all the cytoplasm and the other dies for lack of it.

    There are actually quite a few other notable exceptions. If you do a google/PudMed search on ‘intrinsic asymmetric cell division’ you can find a wealth of information about it.

    That said I’d look to the structure of the cytoskeleton rather than the organelles as the larger repository of epigenetic information.

    I wonder if you have a more specific theory about how and in what part of the cytoskeleton this information would be stored. It seems that many drugs that cause rearrangement, depolymerization or complete disassembly of the most prominent components or the cytoskeleton (microtubules and actin filaments) do not actually kill the cells. In fact, once the drugs are removed, the cytoskeleton reassembles and the cells survive.

    Since any information stored in the actin filaments or microtubules would surely be lost during this process, one would have to surmise that the information is stored elsewhere.

  34. 34
    DaveScot says:

    hrun

    Where is the template that determines the structure of new cytoskeletal components? Surely it doesn’t, as a rule, just grow at random although there are probably random factors that subtly or not so subtly alter its layout. It appears that all new viable daughter cells inherit some of the cytoskeletal structure from the mother cell. It seems as reasonable as any other hypothesis that new cytoskeletal growth and structure is based on the inherited structure. Presuming that all living cells today are links in an unbroken cell line stretching back God only knows how long then the cytoskeletal structure is also part of that unbroken chain of inheritance. One might reasonably presume that descent with modification occurs in the cytoskeleton just like it occurs in DNA.

    In my reading of what is known about the cytoskeleton there are still a lot of question marks as much of it is too fine and finely disbursed to directly observe. For instance, for a long time it was thought that prokaryotes have no cytoskeleton. Now it’s known that they do through improved visual instrumentation. Since cytoskeletal components serve, among other things, as transporation corridors within cells their 3 dimensional layout influences what goes where and when. This is obviously going to effect which proteins get manufactured, in what quantity, where in the cell they are fabricated, where they go after fabrication, and how long they take to get there. Cytoplasm is not a homogenous blob of jelly where things migrate around at random accidently going where they are needed and when. It’s a finely ochestrated machine where things are intentionally transported in timely manner when and where they are needed like in a modern automated manufacturing facility. In the world of automated manufacturing, which is where a lot my professional expertise lies, we call this “just-in-time delivery”. Dell Computer, where I was a systems design engineer for the last decade of my career while the company grew from $1B in annual sales to $40B, owes a lot of its success to refining just-in-time delivery. In manufacturing, time is money. Once you take delivery of components you own them and you pay the cost of capital while the parts, and the finished product as well, are in your custody. We got the time we “owned” the raw materials and finished products down from the weeks our competitors were laboring under to days, then hours, then minutes, and finally we were measuring it in seconds as minutes became too coarse a measure to track improvements. We also ended up tracking “human touches” in seconds to drive labor costs down. One of ways we accomplished this was to require our major suppliers to have warehouses local to our manufacturing facilities. We then had large arrays of loading docks at our assembly plants. Component parts remained on the truck at the loading dock until the moment they were needed to fulfill an order. We didn’t own the parts until they were removed, one component at a time when needed, from the truck. We also didn’t “build-to-forecast” as our competitors did. We built-to-order. We didn’t build a computer until someone placed an order for it and we got the entire process from order to delivery down from weeks to seconds. Living cells employ the same concepts to drive efficiency.

    Cytoskeletal organization brings to mind another great mystery – how are instinctive behaviors coded into DNA? What, for instance, makes birds build nests and sing songs characteristic of their species? Nest building especially is a very complicated process. The materials selected, the location selected, the construction technique, and the final form are all very specific and so characteristic of a species that in most cases an empty nest alone is sufficient to determine which species built it.

  35. 35
    hrun0815 says:

    Where is the template that determines the structure of new cytoskeletal components? Surely it doesn’t, as a rule, just grow at random although there are probably random factors that subtely or not so subtely alter its layout. It appears that all new viable daughter cells inherit some of the cytoskeletal structure from the mother cell. It seems as reasonable as any other hypothesis that new cytoskeletal growth and structure is based on the inherited structure. Presuming that all living cells today are links in an unbroken cell line stretching back God only knows how long then the cytoskeletal structure is also part of that unbroken chain of inheritance. One might reasonably presume that descent with modification occurs in the cytoskeleton just like it occurs in DNA.

    Well, that was exactly my question to you. If it was necessary for the cytoskeleton to be inherited, how does treatment with drugs that depolymerizes and rearranges the cytoskeleton not disrupt this process? Where is the information stored to rebuild the cytoskeleton. And IF the information to rebuild the cyotskeleton is store elsewhere, why would inheritance of the cytoskeleton be necessary?

  36. 36
    DaveScot says:

    hrun

    “how does treatment with drugs that depolymerizes and rearranges the cytoskeleton not disrupt this process?”

    Surely you’re not trying to tell me that complete destruction of the cytoskeleton is not fatal to the cell. I clearly supposed that new cytoskeleton is built as an extension of existing cytoskeleton. Perhaps it would help if you could provide some citations to expermental work with toxins that impair the functionality of the cytoskeleton. I don’t have direct access to subscription sources so I’d appreciate it if it’s in the public domain so I don’t have to burden an underground network of university scientists to email me the restricted parts of the paper beyond the abstract. Many of our members here lack the same access so it also prohibits them from following along as I can’t very well illegally post it for all to see. If it exists, an experiment where the cytoskeleton of a pluripotent stem cell was impaired might be enlightening as to what effect it has on the fully diversified cells that follow.

    That brings up another problem I have with the scientific establishment as it exists today. In my opinion it should be a law that any work which was in part, directly or indirectly, done with public funding should be publically accessable. The high cost of individual subscriptions to peer reviewed trade journals serves to exclude anyone but those enrolled in or employed by universities with site licenses from participation. It’s a closed, guarded community.

  37. 37
    hrun0815 says:

    Surely you’re not trying to tell me that complete destruction of the cytoskeleton is not fatal to the cell.

    That is correct. I did not say that it was not fatal. I said that is was reversible.

    I clearly supposed that new cytoskeleton is built as an extension of existing cytoskeleton. Perhaps it would help if you could provide some citations to expermental work with toxins that impair the functionality of the cytoskeleton.

    Of course it is difficult to establish how complete the destruction of the cytoskeleton is. But imaging by immunofluoresce of the actin filaments shows considerable disruption and depolymerization of actin filaments after e.g. latruncullin or cytochalasin treatment. Here is an abstract that describes some of the effects (Cell Motil Cytoskeleton. 1989;13(3):127-44.):

    The latrunculins are architecturally novel marine compounds isolated from the Red Sea sponge Latrunculia magnifica. In vivo, they alter cell shape, disrupt microfilament organization, and inhibit the microfilament-mediated processes of fertilization and early development. In vitro, latrunculin A was recently found to affect the polymerization of pure actin in a manner consistent with the formation of a 1:1 molar complex with G-actin. These in vitro effects as well as previous indications that the latrunculins are more potent than the cytochalasins suggest differences in the in vivo mode of action of the two classes of drugs. To elucidate these differences we have compared the short- and long-term effects of latrunculins on cell shape and actin organization to those of cytochalasin D. Exposure of hamster fibroblast NIL8 cells for 1-3 hr to latrunculin A, latrunculin B, and cytochalasin D causes concentration-dependent changes in cell shape and actin organization. However, the latrunculin-induced changes were strikingly different from those induced by cytochalasin D. Furthermore, while initial effects were manifest with both latrunculin A and cytochalasin D already at concentrations of about 0.03 microgram/ml, latrunculin A caused complete rounding up of all cells at 0.2 microgram/ml, whereas with cytochalasin D maximum contraction was reached at concentrations 10-20 times higher. The short-term effects of latrunculin B were similar to those of latrunculin A although latrunculin B was slightly less potent. All three drugs inhibited cytokinesis in synchronized cells, but their long-term effects were markedly different. NIL8 cells treated with latrunculin A maintained their altered state for extended periods. In contrast, the effects of cytochalasin D progressed with time in culture, and the latrunculin B-induced changes were transient in the continued presence of the drug. These transient effects were found to be due to a gradual inactivation of latrunculin B by serum and were used to compare recovery patterns of cell shape and actin organization in two different cell lines. This comparison showed that the transient effects of latrunculin B were fully reversible for the NIL8 cells and not for the mouse neuroblastoma N1E-115 cells.

    Since the effects of the drugs were fully reversible, at least in these cells under these conditions the information you are talking about can not be stored in that part of the cytoskeleton.

    I’m sure that with a little bit of time on PubMed one could find more detailed accounts on how exactly these drugs disrupt the cytoskeleton.

    In any case, I did not want to give the impression that your hypothesis is already disproven by available data. However, the reversible effects of these drugs do make it somewhat implausible.

    That brings up another problem I have with the scientific establishment as it exists today. In my opinion it should be a law that any work which was in part, directly or indirectly, done with public funding should be publically accessable. The high cost of individual subscriptions to peer reviewed trade journals serves to exclude anyone but those enrolled in or employed by universities with site licenses from participation. It’s a closed, guarded community.

    I bet that every scientist agrees with you there. That’s why scientists created the open access journals of PLoS, why more and more scientists (with the necessary cash) purchase the rights to freely distribute the pdf versions of their own papers and why scientists pressured the for-profit journals to at least make all papers older than six month freely available.

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    DaveScot says:

    hrun

    I only read of one drug (L-b) having a transient (reversible) effect. The rest as far as the abstract states were permanent. L-b is noted to be slightly less potent than the other two and it was only reversible in the NLI8 cells and not the NIE-15 lines. This is clearly stated in the abstract. I don’t understand how you read something different. That the least potent drug in one of the cell lines causes reversible damage is copacetic with my supposition that new cytoskeleton grows based upon the pattern of the preexisting inherited cytoskeleton. Virtually all the cytoskeleton in an ovum comes directly from the mother cell. The less potent L-b (and L-b only) left enough cytoskeleton intact in one cell line (and one cell line only) to rebuild the skeleton.

    Further, the first effect of all three drugs was inhibition of reproduction which is exactly what we should expect if the cytoskeleton is a controlling factor in the developmental program. I mean, c’mon, the paper even states microfilament-mediated processes of fertilization and early development. That’s essentially the same thing I said in different words. This paper does nothing but support everything I put forward about cytoskeletal involvement with the development program.

  39. 39
    hrun0815 says:

    only read of one drug (L-b) having a transient (reversible) effect. The rest as far as the abstract states were permanent. L-b is noted to be slightly less potent than the other two and it was only reversible in the NLI8 cells and not the NIE-15 lines.

    Latrunculin B is slightly less potent than latrunculin A (still an order of magnitude more potent than cytochalasin D. So I don’t think the potency argument holds.

    Further, the first effect of all three drugs was inhibition of reproduction which is exactly what we should expect if the cytoskeleton is a controlling factor in the developmental program. I mean, c’mon, the paper even states microfilament-mediated processes of fertilization and early development. That’s essentially the same thing I said in different words. This paper does nothing but support everything I put forward about cytoskeletal involvement with the development program.

    Nobody doubts that the cytoskeleton is important for cell division. That does not necessarily mean that there is any specific information stored in the cytoskeleton.

    As I said, I don’t deny the possibility of information stored in the cytoskeleton. I find it unlikely, especially in the light of reversible effects of cytoskeleton disruption, but it’s certainly not impossible. But then, others thought it was unlikely that information was stored in DNA since it was such a simple molecule in comparison to proteins.

    Btw. if you are interested in how additional information is passed on into ova I would suggest to read up on fly development. A lot of maternal information gets passed on in form of RNA that simply leaves a gradient by diffusion from one pole of the egg. The resulting protein gradient then leads to further pattern formation. So, the cytoskeleton is certainly not the only way how maternal information could be passed on– and a lot is know already how it works on the level of mRNAs and proteins.

  40. 40
    DaveScot says:

    hrun

    The fact of the matter is that a lot of non-DNA material (protein and RNA) is inherited and all of it can modulate what’s built from the coded DNA specifications. As an engineer very familiar with complex information processing and control system design it simply appears to me that there isn’t enough information storage capacity in human DNA to build a human body. Just the machinery contained within your skull is beyond it. However, it certainly appears that all this information is somehow crammed into a single cell – all the information needed to build a chicken is in the egg. Therefore I’m simply looking for candidate storage mechanisms within the cell that are inherited along with DNA. Since a large fraction of cytoplasm is inherited and its bulk dwarfs the amount of DNA that’s the only place for an open minded materialist like me to look. While acknowledging the possibility that information might be entering the process from some undetected external supernatural source that’s the last thing I’d consider. Information, as far as we know, doesn’t exist except as patterns in matter and energy. There’s a lot more matter in the cytoplasm than in the DNA molecule and it therefore has a lot more potential for information storage. It’s in there – somewhere. I’d be interested in knowing what the ratio is, by weight, of inherited cell contents broken down into DNA, RNA, and protein. It seems, at least to me, a reasonable working assumption that heritable information is stored commensurately with the capacity of these forms of matter to contain it.

  41. 41
    hrun0815 says:

    The fact of the matter is that a lot of non-DNA material (protein and RNA) is inherited and all of it can modulate what’s built from the coded DNA specifications. As an engineer very familiar with complex information processing and control system design it simply appears to me that there isn’t enough information storage capacity in human DNA to build a human body. Just the machinery contained within your skull is beyond it.

    I guess that matter is debatable and not really up for rigorous debate, since we don’t even really know how much information can be stored in DNA in the first place and since we don’t know how much information is needed to build a human body.

    However, it certainly appears that all this information is somehow crammed into a single cell – all the information needed to build a chicken is in the egg. Therefore I’m simply looking for candidate storage mechanisms within the cell that are inherited along with DNA. Since a large fraction of cytoplasm is inherited and its bulk dwarfs the amount of DNA that’s the only place for an open minded materialist like me to look.

    Given your assumption, I totally agree.

    There’s a lot more matter in the cytoplasm than in the DNA molecule and it therefore has a lot more potential for information storage. It’s in there – somewhere. I’d be interested in knowing what the ratio is, by weight, of inherited cell contents broken down into DNA, RNA, and protein. It seems, at least to me, a reasonable working assumption that heritable information is stored commensurately with the capacity of these forms of matter to contain it.

    Since in virtually all cell devisions, all material that the divided cell contains is inherited, we can just look up the average dry weight of mammalian cells. Of course this is highly dependent on the metabolic activity of the cells, but on average one finds about 50% of the dry weight of a cell to be protein.

    So I don’t really think we can assume that the cytoplasm ‘dwarfs’ the amount of DNA.

    The one thing I still don’t understand, though, is how one would store information in proteins, most of which are distributed in the cytoplasm predominantly by diffusion (and docking to various binding partners) or by structures that polymerize and self-organize from nucleating structures.

    Certainly, a lot of ‘information’ is passed on to daughter cells. Cell walls, membranes, metabolites, proteins, RNA, organelles, … However, to what extent information is stored in this material that is important, for example, for cell differentiation and tissue formation is another question.

    It is clear that some proteins (and inhereted RNAs) are indeed important in this process. As I said, fly development is probably the best studied field in this regard and a huge wealth of information is available in regards to what causes early axis determination, pattern formation and differentiation.

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