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  • Exobiology  (2)
  • group selection  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Can altruism evolve in purely viscous populations? (1992)
    Springer
    Evolutionary ecology 6 (1992), S. 331-341 
    Details
    ISSN: 1573-8477
    Keywords: altruism ; selection ; inclusion fitness ; group selection ; population viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Limited dispersal is often thought to facilitate the evolution of altruism by increasing the degree of relatedness among interacting individuals. Limited dispersal can have additional effects, however, such as local population regulation, that inhibits the evolution of altruism. Many models of structured populations assume that a viscous stage of the life cycle alternates with a global mixing stage, which allows the advantages of interactions among close relatives without the disadvantages of local population regulation. Here we analyse a computer simulation model of ‘pure’ population viscosity, in which offspring are always deposited close to parents and no global mixing stage exists. As expected, limited dispersal generates a high coefficient of relatedness among interacting individuals. Patches of altruists, however, are unable to ‘export’ their productivity to other regions of the landscape and are easily invaded by selfish types from neighbouring patches. Unlike models of alternating viscosity, in which high relatedness and local population regulation can be decoupled, these two opposing effects are inextricably linked in purely viscous populations, which therefore are not conducive to the evolution of altruistic traits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02270969
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    Paper (German National Licenses)
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  • 2
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    In vitro selection of functional nucleic acids (1999)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: In vitro selection allows rare functional RNA or DNA molecules to be isolated from pools of over 10(15) different sequences. This approach has been used to identify RNA and DNA ligands for numerous small molecules, and recent three-dimensional structure solutions have revealed the basis for ligand recognition in several cases. By selecting high-affinity and -specificity nucleic acid ligands for proteins, promising new therapeutic and diagnostic reagents have been identified. Selection experiments have also been carried out to identify ribozymes that catalyze a variety of chemical transformations, including RNA cleavage, ligation, and synthesis, as well as alkylation and acyl-transfer reactions and N-glycosidic and peptide bond formation. The existence of such RNA enzymes supports the notion that ribozymes could have directed a primitive metabolism before the evolution of protein synthesis. New in vitro protein selection techniques should allow for a direct comparison of the frequency of ligand binding and catalytic structures in pools of random sequence polynucleotides versus polypeptides.
    Keywords: Exobiology
    Type: Annual review of biochemistry (ISSN 0066-4154); Volume 68; 611-47
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Constructing high complexity synthetic libraries of long ORFs using in vitro selection (2000)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: We present a method that can significantly increase the complexity of protein libraries used for in vitro or in vivo protein selection experiments. Protein libraries are often encoded by chemically synthesized DNA, in which part of the open reading frame is randomized. There are, however, major obstacles associated with the chemical synthesis of long open reading frames, especially those containing random segments. Insertions and deletions that occur during chemical synthesis cause frameshifts, and stop codons in the random region will cause premature termination. These problems can together greatly reduce the number of full-length synthetic genes in the library. We describe a strategy in which smaller segments of the synthetic open reading frame are selected in vitro using mRNA display for the absence of frameshifts and stop codons. These smaller segments are then ligated together to form combinatorial libraries of long uninterrupted open reading frames. This process can increase the number of full-length open reading frames in libraries by up to two orders of magnitude, resulting in protein libraries with complexities of greater than 10(13). We have used this methodology to generate three types of displayed protein library: a completely random sequence library, a library of concatemerized oligopeptide cassettes with a propensity for forming amphipathic alpha-helical or beta-strand structures, and a library based on one of the most common enzymatic scaffolds, the alpha/beta (TIM) barrel. Copyright 2000 Academic Press.
    Keywords: Exobiology
    Type: Journal of molecular biology (ISSN 0022-2836); Volume 297; 2; 309-19
    Format: text
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    NASA TECHNICAL REPORTS
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