Fig. 4

Biochemical pathway overview (a) and specific steps (b) for cuticular hydrocarbon (CHC) production in Drosophila spp. At each step in the pathway, the number of carbons is listed, followed by a colon and the number of double bonds, followed by ω and the position of the double bond. In (b), the final CHC compounds are boxed, with their abbreviated names; full names are listed in Methods. The degree of shading of each box represents the approximate relative quantity of the compound on the cuticle of D. melanogaster, with darker shades indicating greater quantity. Predominant alternative CHC levels in D. simulans that are instead major (***) or minor (*) compounds in this species are denoted as such and outlined with a dashed box. The genes that were previously identified as affecting CHC production are shown at the appropriate steps in the pathway, as are the deficiencies mapped in the study presented here, represented by bold italicized numbers in brackets, as follows: [1] Df(3L)ED4457; [2] Df(3L)ED4486; [3] Df(3L)XS533; [4] Df(3L)BSC284; [5] Df(3L)BSC223; [6] Df(3L)BSC451; [7] Df(3R)ED5177; [8] Df(3R)ED5330; [9] Df(3R)T-32; [10] Df(3R)BSC471; [11] Df(3R)Cha7; [12] Df(3R)Dl-BX12; [13] Df(3R)H-B79; [14] Df(3R)e-R1; [15] Df(3R)Exel9012; [16] Df(3R)BSC137; [17] Df(3R)Exel6196; [18] Df(3R)Exel6187; [19] Df(3R)ED6220; [20] Df(3R)Exel6203; [21] Df(3R)BSC140; [22] Df(3R)BSC547; [23] Df(3R)ED50003. While the gene(s) present in the deficiencies may affect the production of the affected CHC(s), note that they may instead affect the transport of the CHC(s) to the cuticle. The pathway for the production of branched compounds containing a 2-methyl group is not shown; however, it is predicted to be similar to that of the saturated CHC compounds except that valonyl-CoA would be the immediate precursor rather than acetyl-CoA. Few deficiency lines showed a significant effect for all of the compounds predicted by a gene having an effect on a particular location in the pathway and a single line may contain multiple genes affecting CHC production, each at a different place within the pathway. Thus these placements should be interpreted with some caution