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Upon separation of the protein from the nucleic acid component of tobacco mosaic virus by phenol, using a fast and gentle procedure, the nucleic acid is infective in assays on tobacco leaves. A series of qualitative and quantitative control experiments demonstrates that the biological activity cannot depend on residual proteins in the preparation, but is a property of isolated nucleic acid which is thus the genetic material of the virus.
Within the sedimentation diagram of infective RNA preparations isolated from Tobacco Mosaic Virus, undegraded molecules form a sharp peak with a molecular weight corresponding to the total RNA content of the virus particle. Degradation kinetics by ribonuclease is of the linear, single-target type, indicating that the RNA is single-stranded. The intact RNA of a virus particle thus forms one big single-stranded molecule. Quantitative evaluation of the effect degradation by RNA-ase on the infectivity of the RNA shows that the integrity of the entire molecule is required for its biological activity.
The generation of viral mutants in vitro was demonstrated by treatment of the isolated RNA of Tobacco Mosaic Virus by nitrous acid. This agent causes deaminations converting cytosine into uracil, and adenine into hypoxanthine. Our assay for mutagenesis was the production of local lesions on a tobacco variety on which the untreated strain produces systemic infections only. A variety of different mutants are generated in this way. Quantitative analysis of the kinetics of mutagenesis leads to the conclusion that alteration of a single out of the 6000 nucleotides of the viral RNA is sufficient for causing a mutation.
Applying mild methods of preparation, part of the ribosomes of rabbit reticulocytes are found in aggregates (later called polyribosomes) of up to six ribosomal units. Upon treatment with RNA-ase, they desintegrate into single ribosomes. The fast-sedimenting aggregates are found to be more active in protein synthesis in terms of incorporation of radioactive amino acids, whereas the single ribosomes are more receptive to stimulation by the artificial messenger RNA poly-U. The findings indicate that the linkage of ribosomes into aggregates is due to the messenger RNA. They support a tape-reading mechanism of protein synthesis whereby growth of the peptide chain is accompanied by shifting the active site of the ribosome from one coding group of nucleotides of the messenger RNA to the next.
The short paper introduces the concept of possible branches of double-stranded DNA (later sometimes called palindromes): Certain sequences of nucleotides may be followed, after a short unpaired stretch, by a complementary sequence in reversed order, such that each DNA strand can fold back on itself, and the DNA assumes a cruciform or tree-like structure. This is postulated to interact with regulatory proteins.
Die volle Anwendbarkeit der Physik auf die Biologie des menschlichen Gehirns bedeutet nicht notwendig, dass es ein finitistisches und zugleich vollständiges, algorithmisches Verfahren der Korrelation mentaler mit physikalischen Zuständen geben kann. Vielmehr gibt es Gründe für die Hypothese, dass eine umfassende Theorie der psychophysischen Beziehung prinzipiell unmöglich sein könnte. Diese Auffassung verbindet die Universalität der Physik mit der logischen Begrenztheit des menschlichen Denkens (z. B. in Bezug auf sich selbst) und betrachtet Bewusstsein - die ursprünglichste menschliche Erfahrung - nicht als Randphänomen. ++++ Die Zeitschrift RATIO erschien bis 1987 in einer deutschen und in einer englischen Ausgabe. Die englische Version des Artikels lautet: A. Gierer, The physical foundations of biology and the problems of psychophysics. RATIO XII, No. 1, 1970. S. 47-64.
Full applicability of physics to human biology does not necessarily imply that one can uncover a comprehensive, algorithmic correlation between physical brain states and corresponding mental states. The argument takes into account that information processing is finite in principle in a finite world. Presumbly the brain-mind-relation cannot be resolved in all essential aspects, particularly when high degrees of abstraction or self-analytical processes are involved. Our conjecture plausibly unifies the universal validity of physics and a logical limitation of human thought, and it does not regard consciousness -the most basic human experience - as a marginal phenomenon. ++++ RATIO appeared up to 1987 in both a German and an English version. The German title of this article: Alfred Gierer, Der physikalische Grundlegungsversuch in der Biologie und das psychophysische Problem. RATIO XII, Heft 1, 1970, S. 40-54.
Aggregates of previously isolated cells of Hydra are capable, under suitable solvant conditions, of regeneration forming complete animals. In a first stage, ecto- and endodermal cells sort out, producing the bilayered hollow structure characteristic of Hydra tissue; thereafter, heads are formed (even if the original cell preparation contained no head cells), eventually leading to the separation of normal animals with head, body column and foot. Hydra appears to be the highest type of organism that allows for regeneration of the entire structure from random cell aggregates. The system is particularly useful for studying cell interactions, tissue polarity, pattern formation, and cell differentiation.
The paper addresses the formation of striking patterns within originally near-homogenous tissue, the process prototypical for embryology, and represented in particularly puristic form by cut sections of hydra regenerating a complete animal with head and foot. Essential requirements are autocatalytic, self-enhancing activation, combined with inhibitory or depletion effects of wider range - “lateral inhibition”. Not only de-novo-pattern formation, but also well known, striking features of developmental regulation such as induction, inhibition, and proportion regulation can be explained on this basis. The theory provides a mathematical recipe for the construction of molecular models with criteria for the necessary non-linear interactions. It has since been widely applied to different developmental processes.
Die Münzprägung von Deultum
(1973)
Socioeconomic inequalities are functions not only of intrinsic differences between persons or groups, but also of the dynamics of their interactions. Inequalities can arise and become stabilized if there are advantages (such as generalized wealth including “human capital”) which are self-enhancing, whereas depletion of limiting resources is widely distributed. A recent theory of biological pattern formation has been generalized, adapted and applied to deal with this process. Applications include models for the non-Gaussian distribution of personal income and wealth, for overall economic growth in relation to inequalities and for effects of uncoupling strategies between developing and developed countries. Note added after publication: The equations (14) for the model of the income distribution, with its characteristic non-Gaussian extension towards higher incomes (fig.4), are closely related to the Fokker-Planck equation that is widely applied in many fields of physics.
Die Münzprägung von Bizye
(1981)
Validity of physical laws for any aspect of brain activity and strict correlation of mental to physical states of the brain do not imply, with logical necessity, that a complete algorithmic theory of the mind-body relation is possible. A limit of decodability may be imposed by the finite number of possible analytical operations which is rooted in the finiteness of the world. It is considered as a fundamental intrinsic limitation of the scientific approach comparable to quantum indeterminacy and the theorems of logical undecidability. An analysis of these limits, applied to dispositions of future behaviour, suggests that limits of decodability of the psycho-physic relation may actually exist with respect to brain states with self-referential aspects, as they are involved in mental processes. Limits for an algorithmic theory of the mind-body problem suggested by this study are formally similar to other intrinsic limits of the scientific method such as quantum indeterminacy and mathematical undecidability which are also related to self-referential operations. At the metatheoretical level, hard sciences, despite their reliability, universality and objectivity, depend on metatheoretical presuppositions which allow for multiple philosophical interpretations.
Die Reihe IV enthält alle Werke, Abhandlungen und Aufzeichnungen, mit denen sich Leibniz zu den Fragen und Ereignissen des Staatslebens seiner Zeit geäußert hat, wobei auch die Arbeiten zur Förderung der wirtschaftlichen und geistigen Kultur miteinbezogen sind, soweit damit ein praktischer Zweck verfolgt wurde. Dieser Band umfaßt die Mainzer und die Pariser Jahre. In chronologischer Reihenfolge bietet er in sieben Gruppen die großen, abgeschlossenen Flug- und Denkschriften dar, unter denen Georgius Ulicovius Lithuanus (1669), das „Bedenken über die Securitas Publica“ (1670) und das „Consilium Aegyptiacum“ (1671 bis 1672) hervorragen. Es folgen die „Politischen Gedichte“ (1670 bis 1672), „Politische Entwürfe und Aufzeichnungen“ (1668 bis 1678) sowie die Arbeiten über „Künste und Wissenschaften“ (1667 bis 1676) - vor allem zu Themen der Wissenschaftsorganisation -, die im jetzt vorliegenden Nachdruck um ein Stück (N. 52) vermehrt worden sind. Die in der ersten Auflage als Anhang zu Band 2 erschienenen Überlieferungen, Lesarten und Erläuterungen, Register und Verzeichnisse sowie weitere Auszüge und Untersuchungen über unechte und zweifelhafte Stücke wurden in dieser Nachauflage mit den Texten vereinigt.
Während des ersten Jahrzehnts seiner Tätigkeit in Hannover beschäftigte sich Leibniz vor allem mit der Frage des Gesandtschaftsrechts der fürstlichen Häuser, das auf dem Nimweger Friedenskongreß umstritten war, sowie mit der doppelten Bedrohtheit des deutschen Reiches: im Westen durch die offensive Politik Frankreichs und im Süden durch den Ansturm der Türken. In diesem Zusammenhang entstanden unter anderem die umfangreiche Schrift „Caesarini Fürstenerii de Jure Suprematus ac Legationis Principum Germaniae“ (1677) mit der Kurzfassung „Entretion de Philarete et d’Eugene“ (1677) und begleitende Schriften, die die Interessen des Hauses Braunschweig-Lüneburg vertraten: die sarkastische Flugschrift gegen König Ludwig XIV., „Mars Christianissimus“ (1683), und die unveröffentlicht gebliebenen, vorsichtig abwägenden „Raisons touchant la guèrre ou l’accommodement avec la France“ (1684). Ebenfalls unveröffentlicht gebliebene Studien über das Kriegswesen (1681) und Aufsätze über den Türkenkrieg aus den Jahren 1683 bis 1684 schließen diesen Band ab.