BIOL3045 Lecture Notes - Lecture 8: Histone Methylation, Reactive Oxygen Species, Myogenin
3 Jul 2018
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Department
Course
Professor
Animal Ecological Physiology BIOL3045 460381099
Lecture 8: Epigenetics.
Mechanisms of developmental plasticity Paternal effects
• Parental cellular material passed on to offspring.
• Example: Animals have ROS (Reactive Oxygen Species) defenses of antioxidants and enzymes.
Parental exposure to UV-B increases offspring resilience. Epigenetics influences pre/post zygotic
allow offspring to benefit from the same environment.
Mechanisms of developmental plasticity Molecular effects
Histone methylation Methylation of cytosine bases, restricts access of transcriptional
regulators so gene expression is modified.
DNMT3 new methylation in response to environmental change,
interacts with environment to switch genes on and off. DNMT1
continued pre-existing methylation.
This methylation code is maintained through daughter cells, and
through to offspring.
Example: Myogenin: Transcription factor which regulates muscle
development, its expression is increased at higher temperature with
reduced methylation.
Histone deacetylation HDAC: removal of acetyl groups closes chromatin and deactivates
transcription.
Histone acetylation HAT: addition of acetyl groups opens chromatin and activates
transcription.
Example: Maternal nursing in rats who show maternal nursing to
their young cause lower glucocorticoid expression (stress hormone)
due to histone deacetylation (reduces fear and anxiety levels). This
was confirmed by giving offspring TSA (increases acetylation of
histones) which eliminated the maternal effects on responses to
stress. Maternal nursing causes changes in gene expression to
alterations in histone acetylation.
Read: Lynch, K.E. Darrel, J. K. Nature vs. Nurture. Trends in Ecology and Evolution 29, 2-4, 2014.
• What are the different sources of phenotypic variation? Besides VE, VG, VGXE there is 2COVGE
(correlation between the two) and VEP (variation due to epigenetics).
• What is gene-environment covariance? Different genotypes assort non-randomly in the
environment.
Document Summary
Mechanisms of developmental plasticity: parental cellular material passed on to offspring, example: animals have ros (reactive oxygen species) defenses of antioxidants and enzymes. Epigenetics influences pre/post zygotic allow offspring to benefit from the same environment. Methylation of cytosine bases, restricts access of transcriptional regulators so gene expression is modified. Dnmt3 new methylation in response to environmental change, interacts with environment to switch genes on and off. This methylation code is maintained through daughter cells, and through to offspring. Example: myogenin: transcription factor which regulates muscle development, its expression is increased at higher temperature with reduced methylation. Hdac: removal of acetyl groups closes chromatin and deactivates. Hat: addition of acetyl groups opens chromatin and activates transcription. Example: maternal nursing in rats who show maternal nursing to transcription. their young cause lower glucocorticoid expression (stress hormone) due to histone deacetylation (reduces fear and anxiety levels).
