Traditionally, genomic research was focused on the investigation of DNA sequence which gives rise to the diversity of phenotypes found in nature. It was undoubted that the information which is given by the genomic sequence is the sole factor which is important for the outcome for each individual organism. But since a few decades, a new concept called epigenetics has arisen and shows that we have to modify our knowledge about genetics. “Epi” derives from Greek meaning “on” or “over” and implies that epigenetic mechanisms act on genes via altering the gene expression and regulation without modifying the actual DNA sequence. In epigenetics, we can find the reason why twins (who have the exact same gene sequence) can alter in their phenotype especially concerning their susceptibility to diseases (Fraga et al. 2005; Wong et al.; 2005). Furthermore, it has the potential to answer the question how phenotypic characteristics can alter between generations without a change in the underlying genetic material.
Table of Contents
1. Introduction
2. Lamarck vs. Darwin
3. Epigenetics: Definition and mechanisms
4. Transgenerational epigenetic/maternal effects
5. Behaviour influences and is influenced by epigenetics
6. Conclusion
Objectives and Topics
The essay explores the field of epigenetics in the post-genomic era, specifically investigating how environmental factors and behavioral patterns can modulate gene expression without altering the underlying DNA sequence. It addresses the fundamental question of whether behavior can effectively change our genes by analyzing historical evolutionary theories alongside modern biological evidence.
- Historical context: Comparison of Lamarckian and Darwinian evolutionary theories
- Mechanisms of epigenetics: DNA methylation, histone modification, and chromatin regulation
- Transgenerational inheritance: Maternal influence on offspring phenotype and disease susceptibility
- Behavioral epigenetics: The link between social environment, maternal care, and stress response mechanisms
Excerpt from the Book
Lamarck vs. Darwin:
Broadly seen, the idea behind epigenetics is not new. It appeared 200 years ago, established by Jean - Baptiste Lamarck (1744- 1829). He was a French naturalist and proposed the theory of inheritance of acquired traits, i.e. that evolution occurs when the characteristics from parents, which they have acquired during their lifetime (induced by environmental changes which in turn changed their behaviour), pass on to their offspring. He thought in particular of the use (or disuse) of specific organs (like the giraffe’s neck, see Fig 1) that would lead to its gradual functional improvement (or disappearance). He postulates that these improvements are inheritable and would pass on through generations (so that e.g. the giraffe’s neck becomes longer and longer, Fig 1). He believed that evolution is mainly driven by non-randomly acquired, beneficial phenotypic changes which, he said, are inheritable (in particular, those directly affected by the use of organs). However, his theory was discredited to his time and had been displaced by Darwin’s theory of natural selection in the early 20th century. Darwin (1809 – 1882) ascribed a greater importance to random, undirected changes providing material for natural selection. Both had in common that inheritance of acquired characteristics played an important evolutional role. But Lamarck thought that an organism’s inner need drives evolution, whereas Darwin believed devoutly that natural selection of genetic alterations drives the change in evolution which leads to adaptive characteristics in organisms. Thus, Lamarck’s theory became decried. But by the recent increase of epigenetics’ popularity, his name has come back into modern science.
Summary of Chapters
Introduction: Outlines the shift from traditional genomic research toward the importance of epigenetics in explaining phenotypic diversity.
Lamarck vs. Darwin: Examines historical evolutionary theories and positions modern epigenetics within these traditional frameworks.
Epigenetics: Definition and mechanisms: Defines core epigenetic processes such as DNA methylation and histone modification in relation to gene regulation.
Transgenerational epigenetic/maternal effects: Discusses how maternal environment and nutrition influence the epigenome and phenotype of offspring, using agouti mice as a model.
Behaviour influences and is influenced by epigenetics: Explores how postnatal social experiences and maternal care modulate gene expression and stress responses.
Conclusion: Synthesizes the findings, confirming that the dynamic epigenome allows for rapid adaptation and mediates the interaction between environment and genes.
Keywords
Epigenetics, DNA methylation, Lamarckism, Darwinism, Gene expression, Phenotype, Transgenerational inheritance, Agouti mice, Histone modification, Maternal care, Glucocorticoid receptor, Chromatin structure, Environmental factors, Genomic imprinting, Stress response
Frequently Asked Questions
What is the primary focus of this paper?
The paper examines the field of epigenetics, exploring how non-genetic factors like behavior and environment influence gene expression and phenotype without modifying the actual DNA sequence.
What are the core thematic areas covered?
Key areas include the historical debate between Lamarck and Darwin, the molecular mechanisms of epigenetic change, maternal effects on offspring, and the impact of social behavior on the epigenome.
What is the central research question?
The central question is whether behavior can change our genes, specifically analyzing if environmental and social factors trigger heritable epigenetic modifications.
What methodology is used to support the author's arguments?
The paper employs a comprehensive literature review, analyzing empirical studies on mouse models (agouti mice), rat maternal behavior, and observational data from human famine studies.
What is discussed in the main body of the work?
The main body details epigenetic mechanisms like methylation, the role of maternal nutrition and care-taking in transgenerational programming, and the potential reversibility of these changes.
Which keywords best describe this research?
Core keywords include epigenetics, DNA methylation, transgenerational inheritance, phenotypic variation, and gene-environment interaction.
How does maternal care affect the offspring's stress response in rats?
Studies show that higher rates of maternal care lead to altered DNA methylation of the glucocorticoid receptor gene, resulting in a more resilient hypothalamic-pituitary-adrenal response to stress in adult offspring.
Why are the findings on agouti mice important?
They provide a visual and biological example of how environmental factors, such as maternal diet, can cause heritable changes in fur color and susceptibility to diseases like obesity, independent of the DNA sequence.
Is the epigenetic change permanent?
The paper notes that while epigenetic marks are stable and heritable, they are dynamic and potentially reversible through later interventions, unlike permanent mutations in the DNA sequence.
- Quote paper
- Friederike Lange (Author), 2011, Epigenetics in the post genomic era: Can behaviour change our genes? , Munich, GRIN Verlag, https://www.grin.com/document/179170
