You’ve changed a lot since your last point and are now in the tailbud stage! Your brain and spine are now formed and your tail is beginning to take shape.

Epigenetics

Epigenetics

All cells in the human body contain the same genes, however, we have thousands of different types of cells – so what makes every cell different?

This question is what interested a Cambridge geneticist and embryologist Conrad Waddington, famous for coining the term ‘epigenetics’ in the 1940s.

In his most famous book, “The Strategy of Genes”, Waddington described the concept of the epigenetic landscape – a metaphor for the way that cells adopt different fates through the development of the organism.

The cell is pictured as a marble rolling down a hill with several valleys, able to take different routes. Epigenetics describes the mechanisms which enable cells to interpret the genetic code and give rise to many different cell types (or fates). In other words, it concerns all processes that occur ‘over and above’ (in Greek ‘epi-‘) the level of the genes.

We now define epigenetics as any process that involves stable (and often heritable) changes in the way the genetic code gives rise to the expression of proteins without alterations to the DNA sequence.

What do we know about epigenetics now?

Brain lobes of fruit fly larva with all neural stem cells in red, neural stem cells that are about to divide in green and a histone modification (H3K4me3) in blue. Scale bar is 50µm. Image by Anna Malkowska.

Nowadays, we understand that epigenetic mechanisms are brought about by a few chemical reactions that occur on DNA or proteins that package DNA in the cell nucleus. Importantly, these reactions do not lead to any changes in the genetic code itself.

At the Gurdon Institute, researchers are studying epigenetics in many different contexts. For instance, some modifications can be changed due to external influences, such as diet. These changes can then be inherited by the offspring in so-called ‘transgenerational effects’.

In the institute, researchers study how epigenetic modifications can be inherited for many generations in the small worm C. elegans.

Researchers are also studying the ways that epigenetics influence the development of the brain using the fruit fly Drosophila melanogaster. Epigenetic modifications can regulate the behaviour of stem cells in the brain and therefore the production of new nerve cells. .

Image: The brain of a fruit fly larva with proteins involved in epigenetics labelled in green by Anna Malkowska.

Riddles

  • Three little heads under a window

    look out on the street below

    Come and find us

    and look very closely,

    what colour do we glow?

  • On the wall of Sydney Sussex college you will find a crest with three boar heads and an eagle. What colour are the heads?

*Remember to start your answer with a Capital letter.

”Science is the organized attempt of mankind to discover how things work as causal systems”

— Conrad Waddington in ‘The Scientific Attiude’, 1941.