Mice were kept on an isogenic 129SvJ background. Embryos were obtained from timed pregnancies and dissected at E10.5. 9 dual-color DNA-chip hybridizations of cDNAs from RNA pools of wt and homozygous Dll1tm1Gos embryos respectively were made. Total RNA from pooled samples was obtained according to manufacturer’s protocols using RNeasy Mini or Midi kits (Qiagen). 20µg total RNA was used for reverse transcription and indirectly labelled with Cy3 or Cy5 fluorescent dye according the labelling protocol supplied by Clontech with the Atlas Glass Mouse 1 array. Hybridisation and washing was performed as suggested by Clontech. Slides were scanned for both Cy3 and Cy5 with a GenePix 4000A and images were processed by GenePix Pro 3.0. Mean intensities with subtracted background were normalised so that the median of their ratios has become 1.
