• Question: Can RNA ( especially double stranded) sequencing be carried out at the same rate(as quickly) as DNA sequencing?

    Asked by Oscar to Barbara, Matt, Ravinder, Sophie, Tristan on 9 Mar 2015.
    • Photo: Ravinder Kanda

      Ravinder Kanda answered on 9 Mar 2015:

      It can… but more usually RNA is found in single stranded form. Are you thinking of a particular double stranded RNA?

    • Photo: Matthew Moore

      Matthew Moore answered on 10 Mar 2015:

      Double stranded DNA (dsRNA) would typically be sequenced as complementary DNA (cDNA) so it would be carried out at the same rate, yes!

      As Ravinder said, RNA is typically single stranded and RNA sequencing projects are typically interested in messenger RNA (mRNA) because it indicates, not just which genes are present, but which are being expressed.

      Double stranded RNA viruses however might be of interest to sequence, in which case cDNA would be produced as mentioned. cDNA is produced by complementing the RNA into DNA –an A in the RNA becomes a T in the DNA, a U in the RNA an A in the DNA, C to G and G to C.

      This is then easily converted back on the computer to what the original dsRNA was in the virus!

    • Photo: Barbara Shih

      Barbara Shih answered on 10 Mar 2015:

      I think typically RNA sequencing is converted into complementrary DNA (cDNA) before sequencing. With regards to the “rate” of sequencing, since RNA would require an extra step (making RNA into cDNA), it will always be a little slower. That being said, depending on the sequence, double stranded RNA could be harder to sequence/analyse, depending on how much we know about them already/how big the sequence is/how hard it is to convert it into cDNA.