Epigenetics in context - M.Gavery's Summary

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Epigenetics in context - M.Gavery's Summary

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

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