Biomedical subjects
Publications and source records attributed to J M Labouygues.
The genetic code is an instantaneous code i.e., each codon is deciphered out of ambiguities without knowing other symbols than the constituting nucleotides. Moreover entropy of the genetic source of information has a maximal value.
The groups of codons which correspond to the same amino-acid in the genetic code (synonyms) are compared to theoretical codes constructed so as to resist best to the effects of mutations. The analysis shows that the genetic code presents synonymy structures which are optimized against translation errors.
Protein synthesis can be likened to a particular coded information storage, transmission and execution system. Noise, error or mutations are the essential phenomena to which a living organism is subjected. Genetic coding aims at preserving the integrity of a structure under aggression from the surroundings. It can be shown that the different amino acids translated in the proteins, except the particular case of SER, obey a logical code for optimization of resistance to mutation effects. The study of the structure of this code allows a better comprehension of the logic of life.
Error detection and correction properties are fundamental for informative codes. Hamming's distance allows us to study this noise resistance. We present codes characterized by the resistance optimization to nonsense mutational effects. The calculation of the cumulated Hamming's distance allowing to determine the number of optimal codes and their structure can be detailed. The principle of these laws of optimization of resistance consists of choosing constituent codons connected by mutational neighbouring in such a way that random application of mutations on such a code minimize the occurrence of nonsense n-uplets or terminators. New coding symmetries are then described and screened using Galois's polynomials properties and Baudot's code. Such a study can be applied to any length of the codons. Here we present the principles of this optimization for the most simple doublet codes. Another constraint is discussed: the distribution of optimal subcodes for synonymity and the frequencies of utilization of the different codons. We compare these results to those of the present genetic code, and we observe that all coded amino acids (except the particular case of SER) are using optimal sub-codes of synonymity. This work suggests that the appearance of the genetic code was provoked by mutations while optimizing on several levels its resistance to their effects. Thus genetic coding would have been the best automata that could be produced in prebiotic conditions.
Enumerating Bn numbers using only Bn figures is possible thanks to an overlapping reading of a cyclic sequence built according to Baudot's code. This code allows the genetic code to be screened to show the distribution of the synonyms of the aminoacids. The assignments of the genetic code obey strict laws of optimisation of resistance against the effects of mutations.
We propose a quantitative model which suggests that the present genetic code appeared under the influence of mutations, while optimizing its own resistance against their effects. Its evolution was realized by successive steps in which the number of translated codons grew, whereas the number of terminators decreased. The main constraint of this model is selection against nonsense mutations: the competition among many primitive codes gives advantage to those which resist best to the occurrence of nonsense mutations. The structures of the selected systems converge towards that of the present genetic code. This one appears then as built so as to resist to errors, information noise, mutations.
The connection of codons in the matrix representing the genetic code has to be viewed in conjunction with the optimisation laws against mutation effects. One of the principal effects seems to be represented by selection against non sense. An evolution model by dynamic vocabulary extensive of doublet codes optimised against the occurrence of terminators is presented in detail. This work can be extended to triplet codes.
The aim of this work is the study of the internal laws of logic of the genetic code. If we accept, as a major hypothesis, selection against the occurrence of terminators, this leads us to the optimisation of theoretical code resistance to non sense effects. Depending on how the notion of vocabulary extension is envisaged, several methods exist. One of them is presented here for the simplest doublet codes.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.