Howlett et al. BMC Genomics 2012, 13:211 http://www.biomedcentral.com/1471-2164/13/211 Page 3 of 10 Figure 1 Odorant Receptor genes from M. sexta. Neighbor-joining tree showing similarity of M. sexta and Bombyx OR genes. Bootstrap values from 1000 replicates greater than or equal to 50% are shown. ORs newly identified in this study are marked with an asterisk. The tree was rooted using the Orco co-receptor following previous analyses of this gene family{Robertson, 2006 #111}. Branch lengths are not representative of substitution rate and only vary for presentation purposes. `