• Question: With the use of nano-materials like carbon nano-tubes is there the potential to create small machinery for use in the field of genetic modification? Furthermore, with such machinery, would it be possible to reduce the chance of genetic modification going wrong as with the correct levels of precision with machinery, wouldn't it be possible to be able to modify only a specific part of the DNA sequence?

    Asked by Lopo4567 to Gemma on 16 Mar 2018.
    • Photo: Gemma Chandratillake

      Gemma Chandratillake answered on 16 Mar 2018:

      Hi Lopo,
      I don’t know a lot about nano-materials so this question is really interesting to me – thanks! I guess that there is always potential to develop nano-machinery that is non-biological i.e. non-protein in nature (maybe you will!). I was looking up nanopore DNA sequencing (which I know uses protein pores), and it seems that there are attempts or, at least thoughts, to develop non-biological technology too: https://en.wikipedia.org/wiki/Nanopore_sequencing
      The challenge with genetic engineering is that you need to recognise the exact sequence that you want to modify with such specificity that there are no off-target effects. We can’t see the sequence of a strand of DNA in any way, the highest magnification with electron microscopy allows us to see the strand but no more resolution than that, and obviously we need to be able to do the engineering in the living cell. I’m struggling to think about how a nanomachine would be able to find the specific DNA sequence to target amongst the 3 billion base genome.
      The way we generally recognise specific DNA sequences in the genome is to take advantage of the base-pairing and complementary nature of the two DNA strands….if you a looking for a particular DNA sequence in the genome, you can use a piece of single stranded DNA or an piece of RNA (which is single stranded and pairs with DNA) to find it, as your template will stick to your target due to hydrogen bonding between the bases on the template and target strands – this is how the CRISPR-Cas9 system works: https://www.neb.com/tools-and-resources/feature-articles/crispr-cas9-and-targeted-genome-editing-a-new-era-in-molecular-biology
      There has been lots of tweaking to try to make the system “tighter” i.e. to make it more specific in order to minimise off-target effects. With whole genome sequencing being affordable, it is likely that you would be able to check the genomic sequence of any cell line (or embryo) that you engineered for therapeutic reasons, before and after, to make sure that only the DNA change that you wanted to make had been made. I hope that this makes sense, and I’m sorry that I don’t know more about non-biological nano-machinery – I’ll keep an out for developments in that field now though!