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At least 1,297 records · Page 72Linked to original sources
PubMed1996

ESS patterns: adding pairs to an ESS.

The notion of a pattern of evolutionarily stable strategies was introduced by Cannings and Vickers in 1988 (J. Theor. Biol. 132:387-420). In this paper a specific class of patterns is considered. Suppose that there is an evolutionarily stable strategy (ESS) on some set of n strategies {1,2,...,n} and that new strategies {n + 1,n + 2,...,n + k} are added. Supposing that for this new enlarged conflict there is still an ESS on {1,2,...,n} and also that there are ESSs on {n + i,j} for 1 < or = i < or = k and j epsilon Si [symbol: see text] {1,2,...,n}, the authors investigate the restrictions on the Si. These restrictions are related to certain properties of strong tournaments introduced by Reid and Beineke. We also specify, given the Si, what ESSs of the form {n + i,n + j} can be added.

Animals↗
PubMed1987

Asymmetries of nature and the origin of biomolecular handedness.

New developments in the problem of the origin of the asymmetry of the living systems are reviewed. The time of the appearance of the asymmetry was very probably during the chemical evolution. The asymmetry of weak interaction is still considered small to be the cause of chiral purity. New sources of asymmetry should also be considered, like the one proposed by Gilat.

Biological Evolution↗
PubMed1991

Time reverse automata patterns generated by Spencer-Brown's modulator: invertibility based on autopoiesis.

In the present paper the self-consistency or operational closure of autopoiesis is described by introducing time explicitly. It is an extension of Spencer-Brown's idea of time, however. The definition of time is segregated into two parts, corresponding to the syntax and semantics of language, respectively. In this context, time reversibility is defined by the formalization of the relationship between time and self-consistency. This idea has also been discussed in the context of designation and/or naming. Here we will discuss it in the context of cellular automata and explain the structure of one-to-many type mappings. Our approach is the first attempt to extend autopoietic systems in terms of dynamics. It illustrates how to introduce an autopoietic time which looks irreversible, but without the concept of entropy.

Biological Evolution↗
PubMed1991

Self-reproducing systems: structure, niche relations and evolution.

A formal definition of a self-reproducing system is proposed using Petri nets. A potential self-reproducing system is a set of places in the Petri net such that the number of tokens in each place increases due to some sequence of internal transitions (a transition is called internal to the marked subset of places if at least one of its starting places and one of its terminating places belongs to that subset). An actual self-reproducing system is a system that compensates the outflow of its components by reproduction. In a suitable environment every potential self-reproducing system becomes an actual one. Each Petri net can be considered as an ecosystem with the web of ecological niches bound together with trophic and other relations. The stationary dynamics of the ecosystem is characterized by the set of filled niches. The process of evolution is described in terms of niche composition change. Perspectives of the theory of self-reproducing systems in biology are discussed.

Biological Evolution↗
PubMed1992

Self-organization toward criticality in the Game of Life.

Life seems to be at the border between order and chaos. The Game of Life, which is a cellular automation to mimic life, also lies at the transition between ordered and chaotic structures. Kauffman recently that the organizations at the edge of chaos may be the characteristic target of selection for systems able to coordinate complex tasks and adapt. In this paper, we present the idea of perpetual disequilibration proposed by Gunji and others as a general principle governing self-organization of complex systems towards the critical state lying at the border of order and chaos. The rule for the Game of Life has the minimum degree of perpetual disequilibrium among 2(18) rules of the class to which it belongs.

Biological Evolution↗
PubMed1991

Lineage selection and the capacity to evolve.

The capacity of genetic recombination is an unusual adaptive trait since it is based on the capacity to produce evolutionary change rather than on the capacity to produce better performing individuals. The evolution of this character has been considered to be a case of group or species selection. Alternatively, I introduce a new concept, lineage selection, to account for the evolution of this trait.

Animals↗
PubMed1990

Genes encoding both subunits of phycoerythrocyanin, a light-harvesting biliprotein from the cyanobacterium Mastigocladus laminosus.

Phycocyanin (PC) and phycoerythrocyanin (PEC) are light-harvesting components of the phycobilisome (PbS) from the cyanobacterium Mastigocladus laminosus. These two biliproteins are closely related, and show a particularly high degree of sequence homology in the C-terminal part of their beta-subunits. A 198-bp gene fragment encoding this region of PC from M. laminosus was therefore used as a heterologous hybridization probe to identify the genes coding for PEC from the same organism. A 1.7-kb HindIII fragment was cloned and its sequence determined. Three open reading frames (ORFs) were found on this fragment. The gene coding for the beta-subunit of PEC (pecB) was followed downstream by the alpha-subunit encoding gene (pecA). This gene arrangement had also been found in the PC-encoding (cpc) gene pair from M. laminosus, and is conserved in cpc genes from other organisms. This finding is compatible with a model of evolution of the cpc and pec gene pairs as the product of gene duplication of an ancestral beta- and alpha-subunit-encoding pair. A third ORF starts downstream from pecA. It codes for the 34.5-kDa linker protein, which forms complexes with PEC with a 1:6 stoichiometry in the PbS. Biliprotein- and linker protein-encoding genes are frequently clustered, and this provides mechanisms for the production of the different stoichiometric amounts of these gene products required in the PbS and for coregulation by environmental factors.

Amino Acid Sequence↗
PubMed1994

Engineering aspartic proteases to probe structure and function relationships.

Recently, protein engineering has been used to interconvert homodimeric and homologous single-chain aspartic proteases, with some success. The independent folding of the domains of these proteases has also permitted the engineering of domain-rearranged protease zymogens and the use of individual domains as probes for structural denaturation. In addition, site-directed mutagenesis has provided insights into the catalytic mechanism and specificity of this family of proteases.

Aspartic Acid Endopeptidases↗
PubMed2006

Survival of cancer patients in France: a population-based study from The Association of the French Cancer Registries (FRANCIM).

We present the main results of the first population-based cancers survival study gathering all French registry data. Survival data on 205,562 cancer cases diagnosed between 01/01/1989 and 31/12/1997 were analysed. Relative survival was estimated using an excess rate model. The evolution of the excess mortality rate over the follow-up period was graphed. The analysis emphasised the effect of age at diagnosis and its variation with time after diagnosis. For breast and prostate cancers, the age-standardised five-year relative survivals were 84% and 77%, respectively. The corresponding results in men and women were 56% versus 58% for colorectal cancer and 12% versus 16% for lung cancer. For some cancer sites, the excess mortality rate decreased to low values by five years after diagnosis. For most cancer sites, age at diagnosis was a negative prognostic factor but this effect was often limited to the first year after diagnosis.

Adolescent↗