• Question: Recently there was an experiment on mice which was working to prove that memory may have been passed down to the next generation (the parent mice had been taught to be scared of an object and their childrens children who had never seen that object were still frightened of it when they were introduced to it for the first time. Is it possible that memories have affected our genes as they are the only things passed on to the offspring?

    Asked by jamesroebuck to Samantha, Matt, Karolina, David, Anita on 28 Jan 2014.
    • Photo: Anita Hall

      Anita Hall answered on 28 Jan 2014:

      Hello

      I am not sure exactly which experiment you are talking about; it sounds interesting. Perhaps it refers to the growing research area of ‘epigenetics’ which is about how the activity of genes can be altered by chemical modification and this change in activity (rather than a change in the DNA sequence itself) can be inherited. I would suggest that experiences could alter the anxiety state of a mother which, via her hormones and neuronal circuits, would lead to epigenetic changes that could be inherited by her children and perhaps grandchildren.

Comments

  • Photo: jamesroebuck

    jamesroebuck commented on :

    Hello Anita, I asked a question earlier regarding the the experiment with mice – please could you explain what ‘epigenetics’ are? And also I was wondering does the DNA sequence not need to change in order to change the activity of the gene – can you get a change in the genes behaviour without a change in the structure of the gene itself?
    (p.s this is Abbie – I’m using a joint account)
    Thanks

    • Photo: Anita

      Anita commented on :

      Hello Abbie
      Thanks for the questions

      The Christmas lectures often discussed the sequences of DNA that make up genes and how these can vary through mutations, some of which can change the activity of a gene; this is part of genetics.
      ‘Epigenetics’ refers to the other ways that gene activity can be changed without altering the sequence of the DNA. This gives our cells the control over their genes that is necessary to produce different cell types during development. For each cell type, some genes need to be ‘switched on’ (or ‘expressed’) and others need to ‘switched off’ (or ‘repressed’) for a cell to develop its specialised shape and functions.

      Epigenetics is a quite new and fascinating area of developmental biology and it is also crucial to us understanding how to control stem cell behaviour as we try to develop new cell-based disease treatments. We are also starting to learn about how our ‘epigenetic code’ can be inherited and how, if our epigenetic code is incorrect, it can cause disease and some of the cell problems that develop during ageing.

      I’ll now mention one of the major epigenetic events that occurs in our cells. Our DNA contains gene control sequences which proteins (called transcription factors because they control gene transcription) can bind to. Once bound, these proteins can then trigger or block the expression of a gene. This means that a cell can control which genes are switched on or off by altering access to these control regions. These control regions can be exposed if the DNA is only loosely wrapped around its organising supports (which are called histones). In this open arrangement, transcription factors can easily reach and then bind to gene control regions and switch on gene expression. If a gene needs to be switched off in a certain cell type, the gene’s control regions can be hidden by wrapping the DNA more tightly around the histone supports and often chemically modifying it for example by adding methyl (–CH3) groups. How these methyl groups reduce gene expression is not fully understood yet.

      In this way, a cell can change the organisation of its DNA to change access to gene control sequences. Therefore, gene activity can be altered without changing the DNA sequence itself; this is an example of epigenetics.

      As you might be able to tell, I could think and write about this for ever but I will stop now. I hope I have at least started to answer your question. Best wishes, Anita Hall