Nils Aall Barricelli

On the origin and evolution of the genetic code I. Wobbling and its potential significance

In this paper several properties of the genetic code are interpreted by assuming that wobbling or some remnant of wobbling has originally been a common phenomenon also in the first nucleotide of each codon, and not only in the third nucleotide. Some of the last steps in the evolution of the genetic code are described on the basis of this interpretation of genetic code features. An attempt to outline some of the earlier steps in the evolution of the genetic code is based on the assumption that at an earlier stage wobbling may also have been common in the central nucleotide of each codon. In the last part of the paper the possibility is considered that the pairing rules which characterize wobbling may have been much more common in the past not only in codon-anticodon pairing but also in polymer copying. The advantages of a freer purine-pyrimidine pairing like the one characteristic of wobbling in a primitive (or prebiologic) environment in which nucleotide production was not entirely (or not at all) under biologic control are stressed. This paper is based exclusively on the “Frozen accident” interpretation of the genetic code (Crick, 1968) with a few modifications introduced or implied in the text. No stereochemical codon interpretations and only a minimum of chemical considerations are involved.

On the origin and evolution of the genetic code. II. Origin of the genetic code as a primordial collector language. The pairing-release hypothesis.

Abstract The genetic code is treated as a language used by primordial “collector societies” of tRNA molecules (meaning: societies of RNA molecules specialized in the collection of amino acids and possibly other molecular objects), as a means to organize the delivery of collected material. Its origin is ascribed to the utilization of the complementarity between each tRNA and the genome segment from which it was originally copied, as a means to identify by annealing operations the tRNA molecules returning from their collection trips, and elicit the release of the amino acids they are carrying (the pairing release hypothesis). The gradual conversion of tRNA complements into codon-triplets in the regions of the primordial RNA genomes which specialized in the task of directing the delivery of amino acids by returning tRNA molecules, is ascribed to the removal of genetic redundancy in a gradual reorganization process. A reconstruction of the codon-triplets in one of the earliest genetic codes is attempted by the wobbling reintroduction procedure used in a preceding paper.

Computer studies of the evolution of planetary and satellite systems I. Description of the program: Preliminary tests

In this paper we describe a CDC-Cyber 74 program for computer simulation of the evolution of a system consisting of a large number of objects in orbit around a central body or primary. Some preliminary tests done with the program will also be described.

Forces acting upon an asteroid moving through a meteoroid stream

Forces and accelerations generated by a meteoroid or asteroid stream moving relative to an asteroid or planet are calculated in a few selected examples designed to illustrate main characteristics of the phenomenon. The examples are selected in order to make possible a comparison between collisional and purely gravitational forces (accelerations) and between velocity-dependent and positional forces of gravitational type. The results are used for comparing the orbital perturbations caused by meteorite or asteroid streams with those resulting from secular perturbations. Various implications are discussed.

Virus-genetic theory testing by data processing machines: III. The interpretation of radiation genetic and partial phage experiments in T4. General remarks on the theory-testing results☆

Abstract This is the third of three papers presenting the results of theory testing operations performed by IBM 7090 and 7094 machines. In this paper the results of theory testing operations simulating in the IBM 7094 machine a series of radiation genetic and partial phage experiments are compared with experimental data available for Escherichia coli phage T4. Among the phenomena duplicated by the machine in these tests we may quote: stimulation of recombination by damages in the genetic material, correlation between reciprocal recombinants in damaged and undamaged phages, various effects of cross-reactivation, and various hereditary properties of partial phages. General remarks on the results obtained in this and the preceeding two papers, and their possible implications in genetic theory and in the theory of the origin of the biological evolution process are presented in the last section where the origin of crossing and crossover phenomena as well as the origin of genome circularity is discussed. None of the machine experiments presented in this paper were used for parameter fitting purposes. They are therefore all to be considered as predictions of T4 experiments obtained by the machine on the basis of the theoretic model developed from other data presented in paper II.

Virus-genetic theory testing by data processing machines: II. Fit of classical genetic T4 data☆

Abstract This is the second of three papers presenting the results of theory testing operations performed by IBM 7090 and 7094 machines. In this paper the results of theory testing operations simulating in the IBM 7094 machine a series of classical genetic experiments are compared with experimental data available for Escherichia coli phage T4 and T2. The machine runs (or experiments) were performed in much the same way as the genetic experiments they were supposed to simulate. As input or parent phages we used output or progeny phages obtained in earlier machine runs and punched on IBM cards by the machine. Both wild type phages and phages with several markers (usually 12 markers) were used as input phages. Also phage heterozygotes for one or several markers were often used as input phages. By these procedures we were able to repeat or simulate by the machine a long series of crossing experiments and other types of classical genetic experiments in the IBM 7094 machine and compare them with T2 and T4 data as a test for the theoretical model used. Among the phenomena duplicated by the machine in these tests we may quote: localized negative interference and its effect on the genetic map; clone size of low frequency recombinants; the effect of premature lysis on recombination frequency and other properties of progeny phages; properties of partial heterozygotes and their progeny; etc. The results presented are found to be in good agreement with the genetic experiments described in the literature on phage T4 and T2. Only a portion of the T4 experiments simulated in this paper and none of the experiments simulated in the subsequent paper (radiation-genetic and partial phage experiments) were used for parameter fitting.

Virus-genetic theory testing by data processing machines: I. Basic procedures and models tested☆

Abstract This is the first in a series of three papers presenting results obtained by the use of data processing machines for testing virus-genetic theories. A method is described which permits the representation of the genetic characteristics of a virus and other features, such as labelling or radiation damages of any kind by numbers (to be called genetic data) which can be inserted into the memory of a data processing computer. The genetic theory to be tested can thereafter be translated into a program for the data processing machine that will instruct the machine to perform on the “genetic data” the operations which, according to the theory, would be performed in a cell infected by the virus or viruses specified by the genetic data. The machine will give an output in the form of numbers specifying the genetic characteristics of the progeny viruses, if any, liberated by the infected cell. This output can be compared with experimental data obtained by virus-genetic experiments as a test for the theory. The method is primarily designed to simulate crossing experiments ( not chemical experiments) by a data processing machine. This method has been used to test a variety of partial replica models. The model which has been selected as the one giving the best fit to experimental data is described in this paper. The results of the testing operations, showing how the theoretic predictions obtained by the machine fit a large number of experimental results, are presented in the next two papers of this series.

Computer studies of the evolution of planetary and satellite systems

This paper describes two computer experiments carried out with a CDC-Cyber 74 program (Barricelliet al., 1979) for computer simulation of a large number of objects in orbit about a central body or primary. The first experiment was started with 125 planets of which the two largest ones had coplanar orbits and masses comparable to those of Jupiter and Saturn, respectively. Their semimajor axes and eccentricities were, however, much larger. The smaller planets had a distribution promoting the formation of an axial meeting area. The experiment gives information relevant to the question of focusing of planetary orbits into a common plane and to the question of the formation and stability of an axial meeting area. Together with the next experiment, it also gives information about the development of commensurabilities (or resonances) with the largest planets.The second experiment started with 55 planets none of them with a mass greater than about 20% of Jupiters but several of them with orbits close to a common plane. The aim of the experiment was to investigate whether successive captures followed by planetary fusion (Barricelli, 1972a) could lead to the formation of major planets comparable to Jupiter and Saturn, and in similar orbits. Also this experiment gives information relevant to the commensurability problem.

A note on the asymmetric distribution of the impacts which created the lunar mare basins

In this note the authors are calling attention to the results they have obtained in an earlier computer investigation leading to an interpretation of the asymmetric distribution of the impacts which created many of the lunar mare basins (Barricelli and Metcalfe, 1969; Metcalfe and Barricelli, 1970). These results seem to have been overlooked in the Lunar Science Conference held at Houston last spring, where an investigation of the asymmetric distribution of lunar impacts was proposed.A brief description of the results obtained and the methods used in the investigation is given and a possible extension of the method for the investigation of impacts by objects which are not Earth satellites is discussed.

Preferential perihelion and aphelion distances, and planetary formation

An interpretation of a series of precise relationships (Barricelli, 1972a) between planetary perihelion and aphelion distances, leading to the definition of preferential perihelion and aphelion distances, designated as meeting distances is outlined. The interpretation is based on Alfvéns (1969) jet stream theory and the hypothesis of harmonic resonance between intersecting jet streams.