Figure 2

Principle of mpFISH. A. Colour coding of banding pattern on the chr3 ideogram. B. Distribution of 179 BAC/PAC sequences along the chr3 (from up to down) according to their base pair position. C. Scheme of mpFISH experimental set up. The BAC/PAC clone DNAs shown in B are labelled pair-wise with either biotin-dUTP(red) or digoxigenin-dUTP (green). 100–200 ng of biotin-labelled and the same amount of digoxygenin-labelled probe was dissolved in 10 μl of hybridization mixture and applied to corresponding area on each slide prepared from the ten different tumour cell line samples (1 μl of mixture containing 10–20 ng of each probe per area/slide). This procedure is repeated for all PAC/BAC probe pairs. Using this set up we were able to obtain FISH the results of 20 probes for ten samples in a single experiment. Hybridisation was carried out for 24–72 hours at 37°C under 9 × 9 mm cover slips sealed with rubber cement. Detection and microscopy are performed as described (see mpFISH technique description in Methods).