Structure and evolution of the genetic code viewed from the perspective of the experimentally expanded amino acid repertoire in vivo

Much effort has been devoted recently to expanding the amino acid repertoire in protein biosynthesis in vivo. From such experimental work it has emerged that some of the non-canonical amino acids are accepted by the cellular translational machinery while others are not, i.e. we have learned that some determinants must exist and that they can even be anticipated. Here, we propose a conceptual framework by which it should be possible to assess deeper levels of the structure of the genetic code, and based on this experiment to understand its evolution and establishment. First, we propose a standardised repertoire of 20 amino acids as a basic set of conserved building blocks in protein biosynthesis in living cells to be the main criteria for genetic code structure and evolutionary considerations. Second, based on such argumentation, we postulate the structure and evolution of the genetic code in the form of three general statements: (i) the nature of the genetic code is deterministic; (ii) the genetic code is conserved and universal; (iii) the genetic code is the oldest known level of complexity in the evolution of living organisms that is accessible to our direct observation and experimental manipulations. Such statements are discussed as our working hypotheses that are experimentally tested by recent findings in the field of expanded amino acid repertoire in vivo. Received 30 June 1999; accepted 9 July 1999     

Genetic ecology: A new interdisciplinary science,fundamental for evolution,biodiversity and biosafety evaluations

Genetic ecology is the extension of our modern knowledge in molecular genetics to studies of viability, gene expression and gene movements in natural environments like soils, aquifers and digestive tracts. In such milieux, the horizontal transfer of plasmid-borne genes between phylogenetically distant species has already been found to be much more frequent than had been expected from laboratory experience. For the study of exchanges involving chromosomally-located genes, more has to be learned about the behaviour of transposons in such environments. The results expected from studies in genetic ecology are relevant for considerations of evolution, biodiversity and biosafety. The role of this new field of research in restoring popular confidence in science and in its biotechnological applications is stressed.     

Peptides as DNA mimics: cross-reactivity and mimicry in systemic autoimmune diseases

No Abstract. Received 21 February 2002; received after revision 16 May 2002; accepted 14 June 2002