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Epigenetics in context - M.Gavery's Summary
 

Epigenetics in context - M.Gavery's Summary

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    Epigenetics in context - M.Gavery's Summary Epigenetics in context - M.Gavery's Summary Presentation Transcript

    • Epigenetics in Context: From Ecology to EvolutionSummary – M.Gavery
    • Questions Addressed
      The role of epigenetics in evolution:
      How much is inherited
      How is it inherited
      What and how much is reset
      Chromatin modification
      Theory
      The role of epigenetics in ecology
      Natural variation
      Phenotypic plasticity
      Response to stress
      What ecologically relevant organisms can we/should we study
    • Mechanisms
      DNA methylation
      Histone modifications
      Small RNAs
      Non-coding RNAs
    • Tools
      Bisulfite sequencing
      ChIP/MeDIP-seq& ChIP/MeDIP-chip
      RNA-seq
      MSAP – CE, GeneMapper
      SureSelect Target Enrichment System (Agilent)
      Software: ChIPDiff, SICER
    • Study Systems
      Arabidopsis, Drosophila..yawn ;)
      Nectar yeasts
      Dandilions
      Mimulus
      Insects: wasps, locusts
      Algae
      Fish
    • Fish
      European Sea Bass (F. Piferrer)
      EPIGEN-AQUA
      heat shock of embryo suppresses aromatase
      what is mechanism? Bisulfite sequenced promoter
      found differential methylation in promoter of males and females
      relationship between expression and methylation is weak
      Darters (T. Smith)
      AFLP and MSAP in populations from the same river
      Guppies (A. Lopez-Sepulchre)
      Cool system, ‘ecotypes’ in high predation and low predation environments – interested in epigenetics http://www.cnas.ucr.edu/guppy/
    • Theory
      Carja et al 2011 – Equilibrium for phenotypic variance in fluctuating environments
      Jason Wolf – epistatic selection can favor imprinting when interacting loci share imprinting status
      Sinead Collins- ephemeral mutations (e.g. DNA methylation) can speed up fitness increases
      Decouples timing of adaptive changes in phenotype from genotype, “hand over hand”
    • What ‘writes’ DNA methylation
      How do marks know where to go?
      Arabidopsis (numerous)
      role of transposons was greatly discussed
      transposons are silenced by DNA methylation
      lots of experimental examples shown (e.g. epiRILs, DDM mutants)
      C.elegans (B. Kelly)
      transcription itself can write epigenetics
      Cancer Cells (A. Bar)
      ‘microevolution’ – 350 generations
      local v. regional (signaling from ind.CpG or lifiting of repressive chromatin state)
    • DNA Methylation and Stress
      Mostly shown in plants
      different stresses: salinity, heat
      Different levels of ‘inheritance’
      e.g. extreme heat stress ‘primed’ plants only when exposed for 2 generations
      phenotype & epigenetic mark still being understood
      Most ecologically relevant model: nectar yeast (Carlos Herrera)
    • Examples of Increased Variation
      Dandilions(K. Verhoeven)
      stress = increased variability in phenotype
      zebularine treatment – results variable in phenotype (‘no robust response’)
      Nectar Yeast (C. Herrera)
      add 5-aza = no effect in optimized environments, big effect in non-optimized (but phenotypes variable between these)
    • Sensitization: decay with threshold recall(Eva Jablonka)
      original stimulus:
      stimulus
      stimulus
      phenotype
      phenotype
      + + + + + + + + + + +
      + + + + + +
      + + + + + +
      decay:
      smaller stimulus to reach threshold:
      + + + + +
    • Best Things
      Incorporated genetics – must be considered together (e.g. epigenetic status effects recombination, transposons effect epigenetic status)
      Ecology – need to study relevant stressors, understand natural populations
      Major challenges – each stress has a different response, may need to look at bigger picture (fitness as variation, instead of specific response?)
      Kava, swimming, x2 desserts/day