Editing Comparative genomic hybridization (section)

===Hybridization===
8–12μl of each of labelled test and labelled reference DNA are mixed and 40&nbsp;μg Cot-1 DNA is added, then precipitated and subsequently dissolved in 6μl of hybridization mix, which contains 50% formamide to decrease DNA melting temperature and 10% dextran sulphate to increase the effective probe concentration in a saline sodium citrate (SSC) solution at a pH of 7.0.<ref name="Weiss,Hermsen,Meijer,VanGrieken,Baak,Kuipers,VanDiest" />

[[Denaturation (biochemistry)|Denaturation]] of the slide and probes are carried out separately.  The slide is submerged in 70% formamide/2xSSC for 5–10 minutes at 72&nbsp;°C, while the probes are denatured by immersion in a water bath of 80&nbsp;°C for 10 minutes and are immediately added to the metaphase slide preparation. This reaction is then covered with a coverslip and left for two to four days in a humid chamber at 40&nbsp;°C.<ref name="Weiss,Hermsen,Meijer,VanGrieken,Baak,Kuipers,VanDiest" />

The coverslip is then removed and 5 minute washes are applied, three using 2xSSC at room temperature, one at 45&nbsp;°C with 0.1xSSC and one using TNT at room temperature. The reaction is then preincubated for 10 minutes then followed by a 60-minute, 37&nbsp;°C incubation, three more 5 minute washes with TNT then one with 2xSSC at room temperature.  The slide is then dried using an ethanol series of 70%/96%/100% before counterstaining with DAPI (0.35 μg/ml), for chromosome identification, and sealing with a coverslip.<ref name="Weiss,Hermsen,Meijer,VanGrieken,Baak,Kuipers,VanDiest" />