Figure 2

Overview of the approach for quantification of DNA damage. (a) Primers are designed that amplify fragments of several sizes. The schematic representation shows the position of oligonucleotides and the picture below shows the corresponding PCR products (amplified from genomic DNA) separated on a 1.8% agarose gel. (b) The various sized fragments are amplified using real-time PCR. This representative plot of fluorescence observations shows amplification of herring DNA from a single sea lion faecal DNA extraction. PCR fragment sizes from left to right are 69 bp, 123 bp, 184 bp, 226 bp and 304 bp. (c) Copy number (Ax) estimates are obtained for each of the amplicon sizes (x). The plot shows the amount of herring DNA in a sea lion faecal sample (#7). (d) The data is then log-transformed and a linear model is fitted in order to estimate the probability of a nucleotide being damaged (λ).