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Homo- and Hetero-philic Cell Adhesion Motifs

  1. Günter Wächtershäuser - Patent Lawyer, Organic Chemist, Origins of Life, and Evolutionary Biochemistry W�chtersh�user, G�nter
    • Before Enzymes and Templates: Theory of Surface Metabolism
    • Microbiological Reviews: Vol. 52, No. 4, pp. 452-484
    • December 1988
    • [Pubmed]
    • In An Iron-Sulfur World
    • Origins of Life and Evolution of the Biosphere: Vol. 20, pp.173-176
    • 1990
    • Biomolecules: The Origin of Their Optical Activity
    • Medical Hypotheses: Vol. 36, No. 4, pp. 307-311
    • December 1991
    • [Pubmed]

  6. _______________________________________

    "From the point of view of evolution, however, they [low-propensity branch reactions] constitute the wellspring of genuine evolutionary variations.

    For on occasion, one of these (low-propensity) branch constituents will show a positive feedback effect by turning into a catalyst for a rate-limiting reaction within the autocatalytic cycle(s).

    Such a catalytic effect is itself cyclic: the catalyst (e.g. TPP) combines with a reactant in the autocatalytic cycle; the catalyst-reactant adduct undergoes subsequent conversion into a catalyst-product (faster than conversion of the reactant into product); finally, the catalyst-product adduct is cleaved into the product and the catalyst."

    G�nter W�chtersh�user
    _______________________________________

    • Groundworks for an Evolutionary Biochemistry: The Iron-Sulphur World
    • Progress in Biophysics and Molecular Biology: Vol. 58, No. 2, pp.85-202
    • 1992
    • [Pubmed]
    • The Cradle Chemistry of Life: On the Origin of Natural Products in a Pyrite-Pulled Chemoautotrophic Origin of Life
    • Pure & Applied Chemistry: Vol. 65, No. 6, pp. 1342-1348
    • 1993
    • QD 1.P86 v.65 n.6 1993

    • _______________________________________

      The Scientific Merit of the Theory

      "[I]t would be preposterous to assume that these first attempts at retrodiction are likely to hit upon the true historic sequence of events.

      The scientific merit of such a theory of biochemical evolution is its fertility in producing increasingly comprehensive and powerful explanations.

      Ultimately, the progressive amendments of the theory, guided by methodological postulates and by experimental tests, should lead to a correlation of the various lines of pathway evolution with each other and with the appearance of enzymes: in short,

      a historically ordered table of biochemistry.

      I expect that this may be a precondition for making significant progress in the evolutionary explanation of [the] genetic machinery, the genetic code and the process of translation."

      "Progress in science is in my opinion crucially dependent on the methodological efforts and ultimately on the theory of knowledge.

      Of course, a scientist holding the wrong theory of knowledge can still have extraodinary achievements in his field; other scientists, subscribing to the right theory of knowledge, may still be barren.

      Yet it seems to be clear to me that an unsound methodology tends to be a hinderance while sound methodological reflections tend to be helpful.

      The methodology of the present investigation is wholly indebted to the epistemology of Karl R. Popper and notably to the three central tenets of his philosopy:"

      The rejection of inductivism (Popper, 1959, 1963, 1972, 1979, 1983b) frees us from the illusionary commitment that we should induce a general theory from the incidentally obtained or known particulars.

      Instead, we can not treat the body of known particulars as constituting the central part of our problem of explanation.

      The rejection of reductionism (Popper, 1972, 1974) frees us from the imagined task to derive biology from chemistry.

      It opens our eyes to the fact that the problem of an evolutionary theory of biochemistry is a biological problem, ant that its solution will be a biological theory.

      The laws of chemistry are basic of course, yet ancillary; and they are so in two ways.

      The known law of chemistry are welcome restrictions on the chaos of biological possibilities.

      But so far unknown universal laws of chemistry are also needed and some of them indeed entailed by the biological theory presented here [Wachtershauser, 1992].

      They form the basis for new kinds of experiments, exposing the theory to crucial tests and potential refutation.

      Abandoning determinism (Popper, 1972, 1974, 1983c, 1990a) we come to see that chemical reality covers more than high-propensity ("deterministic") reactions.

      In fact, low-propensity ignitions seem to be the very chemical stuff of biochemical evolution.

      Admittedly, present biochemistry is largely concerned with the study of deterministic processes.

      But it seems to me that ignitions of new autocatalytic cycles, (i.e. mutations), tend to go beyond deterministic chemistry and increasingly so with progessing evolution, which means that biochemical evolution cannot be properly appreciated within a deterministic framework.

      "According to Popper's methodology of science, it is the aim of a scientific theory to predict and to explain.

      And alternative theories compete for the greatest predictive power (testability) and for the greatest explanatory power - for explaining the most facts with the fewest assumptions.

      A theory on the origin of life is scientific to the extent that it satisfies these aims.

      When we explain, we reduce known facts to unknown theoretical entities (Popper, 1963);

      known reaction products to an unknown reaction mechanism or to unknown intermediates;

      Known extant organisms to unknown missing links; known biochemical pathways to an unknown origin of life.

      Chemically speaking, an evolutionary explanation of todays life by a hypothetical origin means the treatment of evolution as a gigantic reaction mechanism, stretching over some four billion years with myriads of reaction intermediates.

      Biologically speaking, such evolutionary explanation means to draw lines of descent from the extant organisms back towards the first reproducing metabolist.

      Both approaches emphasize different aspects of the same overall process. The chemical approach emphasizes individual reations within a metabolism.

      But it tends to fail with unstable changeover from one stable metabolism to another stable metabolism.

      The biological approach emphasizes the sequence of changeovers and it tends to take a whole organism (metabolist) as its smallest unit.

      My theory on the chemo-autotrophic origin and early evolution of life combines both approaches: by postulating a primordial organism which is characterized in chemical terms, and by drawing evolutionary linkages to extant organisms.

      In order to bring out best the explanatory power of the theory (plurality of explained facts and paucity of explaining assumptions) it is presented in a deductive format with few independent postulates and many derived theorems.

      It is important to note, however, that such derivations will have to make extensive use of a large body of background knowledge in the fields of organic, inorganic, and physical chemistry as well as geochemistry.

      G�nter W�chtersh�user
      _______________________________________

      Origin of Life: Life As We Don't Know It
    • Science: Vol. 289, No. 5483, pp. 1307-1308
    • August 25, 2000
    • [Pubmed]
  13. Wada, Hiroshi; Saiga, Hidetoshi; Satoh, Noriyuki; Holland, Peter W.H.
  14. Wade, Rebecca C.; Gabdoulline, Razif R.; Ludemann, Susanna K.; Lounnas, Valere
  15. Wagner, G�nter P.; Amemiya, Chris; Ruddle, Frank
  16. Wagner, G�nter P.; Laubichler, Manfred D.
  17. Wandell, Brian A.
  18. Wang, Hsien-yu; Malbon, Craig C.
  19. Wang, Qing-jun
  20. Wang Yibin; Jones, Frederick S.; Krushel, Leslie A.; Edelman, Gerald M.
  21. Warshel, Arieh
  22. Watson, James D.
    • Early Speculations and Facts about RNA Templates
    • in: The RNA World - 2nd Edition
      • Edited by Raymond F. Gesteland; Thomas R. Cech; John F. Atkins
      • Monograph 37: pp. xvii-xxv
    • Cold Spring Harbor Labortory Press
    • QP 623.R6 1999
  25. Weber, Arthur L.
  27. Weber, Renee
    • Dialogues With Scientists and Sages: The Search for Unity
    • Routledge & Kegan Paul
    • Q 175.D6325 1986

  28. Weichert, Charles Kipp
    • Elements of Chordate Anatomy
    • McGraw-Hill
    • QL 805.W4 1967

  29. Weinhold, Frank; Landis, Clark R.
  30. Weinstock, Marta
  31. Wells, James M.; Melton, Douglas A.
  32. Welsh, J.P.; Llinas, Rodolfo R.
    • Some Organizing Principles For The Control of Movement Based on Olivocerebellar Physiology
    • Progress in Brain Research: Vol. 114, pp. 449-461
    • 1997
    • [Pubmed]

  33. Harold B. White III - Biochemist, Coenzymes in Origin of Life White III, Harold B.
  36. Whiting, B.A.; Barton, R.A.
  37. The barracks at Buchenwald. Elie Wiesel is among the prisoners on the far right of the center bunk. This photograph was taken on April 16, 1945, just after the liberation of Buchenwald. (Corbis-Bettman)Whittaker, J.R.
  38. Wicht, Helmut; Northcutt R. Glenn
  39. _______________________________________

    "Sometimes we must interfere. When human lives are endangered,

    when human dignity is in jeopardy, national borders and sensitivities become irrelevant. Whenever men or women are persecuted because of their race, religion, or political views, that place must - at that moment - become the center of the universe."

    Elie Wiesel
    _______________________________________

    Elie Wiesel - Writer/Nobel Peace Prize Winner, Survivor of Birkenau, Auschwitz, Buna, and Buchanwald concentration campsElie, Wiesel
    • Night
    • Bantam Books
    • D 810.J4.W513 1960
  41. Willie, Holger; Michelitsch, Melissa D.; Guenebaut, Vincent; Supattapone, Surachai; Serban, Ana; Cohen, Fred E.; Agard, David A.; Prusiner, Stanely B.

  42. _______________________________________

    Group Selection Vs. Individual Selection:
    A Classic Multilevel Selection Problem

    "In principle, natural selection can operate simultaneously at more than one level of the hierarchy. The classic multilevel selection problem is the evolution of altruism in groups of socially interacting individuals. Selfish individuals are more fit than alturists within each group (within-group selection), but groups of altruists are more fit than groups of selfish individuals (among-group selection). What evolves in the total population depends on the relative strength of the opposing levels of selection."

    David Sloan Wilson
    _______________________________________

    Williams, Alan F; Barclay, A. Neil
  43. Williams, Robert Joseph Paton; Frausto Da Silva, Joao Jose R.
  45. David Sloan Wilson - Evolutionary Biologist, Individual Vs Group Selection Wilson, David Sloan
  48. Edward O. Wilson - Evolutionary Biologist, Entomologist, Humanist Wilson, Edward O.
    • Sociobiology
    • Belknap Press of Harvard University Press
    • QL 775.W542 1980
    • Naturalist
    • Island Press - Shearwater Books
    • QH 31.W64.A3 1994
  51. Wilson, Edward O.; Bossert, William H.
    • A Primer of Population Biology
    • Sinauer Associates
    • QH 43.W493 1971

  52. Winkelman, Michael
  53. Wirth, Sylvia; Yanike, Marianna; Frank, Loren, M.; Smith, Anne C.; Brown, Emery N.; Suzuki, Wendy A.
  54. Carl R. Woese - Microbiologist, Origin of Life, RNA Phylogenies Woese, Carl R.
  58. Woese, Carl R.; Kandler, Otto; Wheelis, Mark L.

  59. _______________________________________

    - The Darwinian Threshold -

    "The degree of connectedness of the componetry of the cell has profound evolutionary implications.

    If a cell was simple and highly modular in organization, HGT [Horizontal Gene Transfer] would play a stronger role in its evolution than otherwise.

    Indeed, were that organization simple and modular enough, all of the componetry of a cell could potentially be horizontally displaceable over time.

    The organismal genealogical record would be ephemeral; no stable record could exist.

    Suppose that the primitive ancestors of modern cells were of this nature.

    That would mean that at its beginning, cellular evolution would have been mainly driven by HGT.

    In its subsequent evolution a primitive cell of this type would become ever more complex, idiosycratically connected, and thereby increasingly refractory to horizontal gene acquisition, especially the more spectacular forms of it.

    In other words, there would come a stage in the evolution of cellular organization where the organismal genealogical trace (recorded in common histories of the genes of an organism) goes from being completely ephemeral to being increasingly permanent.

    This point in evolution, this transition, is appropriately call[ed] the "Darwinian Threshold".

    On the far side of that Threshold "species" as we know them cannot exist.

    Once it is crossed, however, speciation becomes possible.

    The Darwinian Threshold truly represents the Origin of Species, in that it represents the origin of speciation as we know it."

    Carl R. Woese
    _______________________________________

    Wohler, Friedrich
  60. Wolf, Yuri I.; Karev, Georgy; Koonin, Eugene V.
  61. Wood, John T.

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