On this paper we explored the level complexity of the combinatorial olfactory code that allows mammals with a repertoire of about thousand putatively active olfactory receptors encoded in their genomes to recognize and identify a much larger repertoire of odorant molecules. To that end we cloned 38 canine OR genes belonging to the same OR gene family and transiently expressed them in a sub-clone of embryonic human kidney cells (HEK293) permanently expressing the G_olf subunit. Using a Ca2+ imaging approach we established for example that as many as 26 out of the 38 cloned OR elicited a Ca2+ response when exposed to octanal whereas 10 responded to nonanal, other aldehydes providing intermediate responses. Altogether, these results demonstrated that the combinatorial code is quite complex in support to the highly developed sense of olfaction demonstrated by dogs

• [ Supplementary Information ]
  table1 = primers sequences
  table2 = proteine sequences
  table3 = nucleotide sequences