Lecture Notes: Nature vs. Nurture and Epigenetics

Introduction

• Speaker: H Maria Castro
• Begin with a personal anecdote about pregnancy with identical twins.
• Reflection on nature vs. nurture debate influenced by pregnancy.

Nature vs. Nurture

• Identical twins provide insights into genetics (nature) versus environment (nurture).
• Studies show:
  • Certain traits (IQ, criminal tendencies) primarily affected by DNA.
  • Other traits (depression in men, political preferences) influenced more by environment.
• Differences observed in identical twins raised in the same household.
  • Examples: food preferences, aptitudes, health differences (autism, asthma).

Introduction to Epigenetics

• Definition: Epigenetics refers to modifications on DNA and histones that affect gene expression.
  • Chemical tags influence DNA accessibility and gene reading.
• Chromatin: DNA wrapped around histones, creating DNA packaging in cells.
  • Functional units are the genes encoded in DNA.

Role of Epigenetics

• Epigenetic marks can condense or decondense chromatin, affecting gene expression.
• Differentiation of cells (e.g., muscle vs neuron) is guided by epigenetic instructions despite identical DNA.

Timing of Epigenetic Information

• Laying down of epigenetic marks occurs during embryonic development.
• Environmental influences on epigenetics:
  • Maternal diet, lifestyle, and stress can impact fetal development.

Case Study: Agouti Gene in Mice

• Agouti gene affects obesity and health; can be turned off by silencing epigenetic marks.
• Maternal diet during pregnancy can influence offspring traits (thin, brown, healthy vs. fat, yellow, disease-prone).

Human Implications

• Maternal behavior correlates with children's long-term health (e.g., obesity, cardiovascular disease).
• Epigenetic effects can be transgenerational:
  • Lifestyle choices of parents affect future generations.

Epigenetics Beyond Development

• Epigenetic marks also influence post-birth development, particularly in brain health.
• Study with rats shows that nurturing behavior from mothers affects stress handling in offspring (glucocorticoid receptor gene).

Reversibility of Epigenetic Marks

• Encouraging aspect: epigenetic marks can be reversed.
• Research is ongoing for drugs that can target and reverse detrimental epigenetic modifications, especially in cancer therapy.

Future Directions

• Focus on how to target harmful epigenetic marks while preserving beneficial ones.
• Lifestyle choices can positively influence the epigenome:
  • Healthy foods, avoiding harmful substances (cigarettes, drugs), managing stress.

Conclusion

• Empowering idea: we can influence our genes and long-term health through lifestyle decisions.
• Call to action to treat the epigenome kindly for better health outcomes, including for future generations.
• End with gratitude to the audience.