Fun papers

From: Anders Sandberg (asa@nada.kth.se)
Date: Thu Jul 17 2003 - 08:47:25 MDT

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    Some fun papers:

    How the interplay between water competition and pests help stabilize
    Balinese Rice farming in a distributed manner.

    DNA microarray studies of the DAF-16 pathway of ageing in C elegans

    Age-related learning deficits and brain oxidative stress ameliorated by
    superoxide dismutase/catalase mimetics

    Nature also has an editorial (Nature 424, 237 (17 July 2003);
    doi:10.1038/424237a, Don't believe the hype ) and a news feature (Nature
    424, 246 - 248 (17 July 2003); doi:10.1038/424246a Nanotechnology: A
    little knowledge... ) on nanotech resistance.
     

    http://www.santafe.edu/sfi/publications/wpabstract/200305030

    SFI Working Paper Abstract 2003

    Cooperation in Balinese Rice Farming

    Author(s): J. Stephen Lansing and John H. Miller

    Paper #: 03-05-030

    Abstract:
    For centuries Balinese rice farmers have been engaged in cooperative
    agricultural practices. Without centralized control, farmers have
    created a carefully coordinated system that allows productive farming in
    an ecosystem that is rife with water scarcity and the threat of disease
    and pests. We develop a simple game-theoretic model, inspired by a
    generation of careful anthropological field work, to provide a compact
    explanation for many of the most salient features observed in the
    system. We find that while externalities caused by either water scarcity
    or pests would, in isolation, be expected to cause a serious failure in
    the system, the ecology of the rice farming system links these two
    externalities in such a way that cooperation, rather than chaos,
    results. We test key features of the model through both natural and
    computational experiments and a field survey focused on the strategic
    motivations of the farmers.

    Nature 424, 277 - 283 (17 July 2003); doi:10.1038/nature01789

    Genes that act downstream of DAF-16 to influence the lifespan of
    Caenorhabditis elegans

    COLEEN T. MURPHY*, STEVEN A. MCCARROLL?, CORNELIA I. BARGMANN?, ANDREW
    FRASER?, RAVI S. KAMATH?, JULIE AHRINGER?, HAO LI* & CYNTHIA KENYON*
     
    Ageing is a fundamental, unsolved mystery in biology. DAF-16, a
    FOXO-family transcription factor, influences the rate of ageing of
    Caenorhabditis elegans in response to insulin/insulin-like growth factor
    1 (IGF-I) signalling. Using DNA microarray analysis, we have found that
    DAF-16 affects expression of a set of genes during early adulthood, the
    time at which this pathway is known to control ageing. Here we find that
    many of these genes influence the ageing process. The insulin/IGF-I
    pathway functions cell non-autonomously to regulate lifespan, and our
    findings suggest that it signals other cells, at least in part, by
    feedback regulation of an insulin/IGF-I homologue. Furthermore, our
    findings suggest that the insulin/IGF-I pathway ultimately exerts its
    effect on lifespan by upregulating a wide variety of genes, including
    cellular stress-response, antimicrobial and metabolic genes, and by
    downregulating specific life-shortening genes.

    PNAS | July 8, 2003 | vol. 100 | no. 14 | 8526-8531

    Reversal of age-related learning deficits and brain oxidative stress in
    mice with superoxide dismutase/catalase mimetics

    Ruolan Liu *, Ingrid Y. Liu *, Xiaoning Bi , Richard F. Thompson *,
    Susan R. Doctrow , Bernard Malfroy and Michel Baudry *

    Oxidative stress has been implicated in cognitive impairment in both old
    experimental animals and aged humans. This implication has led to the
    notion that antioxidant defense mechanisms in the brain are not
    sufficient to prevent age-related increase in oxidative damage and that
    dietary intake of a variety of antioxidants might be beneficial for
    preserving brain function. Here we report a dramatic loss of learning
    and memory function from 8 to 11 months of age in mice, associated with
    marked increases in several markers of brain oxidative stress. Chronic
    systemic administration of two synthetic catalytic scavengers of
    reactive oxygen species, Eukarion experimental compounds EUK-189 and
    EUK-207, from 8 to 11 months almost completely reversed cognitive
    deficits and increase in oxidative stress taking place during this time
    period in brain. In particular, increase in protein oxidation was
    completely prevented, whereas increase in lipid peroxidation was
    decreased by 50%. In addition, we observed a significant negative
    correlation between contextual fear learning and levels of protein
    oxidation in brain. These results further support the role of reactive
    oxygen species in age-related learning impairment and suggest potential
    clinical applications for synthetic catalytic scavengers of reactive
    oxygen species.

    -- 
    -----------------------------------------------------------------------
    Anders Sandberg                                      Towards Ascension!
    asa@nada.kth.se                            http://www.nada.kth.se/~asa/
    GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
    


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