Reassessment of mapping of the E homeotic gene complex of Bombyx mori by linkage analysis and in situ hybridization with an Antennapedia clone as a probe

The gene for a recessive mutant named “soft and limp” (gene symbol sol) was shown to be linked with the E homeotic pseudoalleles previously mapped to the distal end of the 6th linkage group. A three-point test involving one of the E genes (E^ca) and the F gene localized on the same linkage group indicated that the arrangement of these three gene loci is in the order of sol—E^ca—F. Taking the recombination values and correction factors into account, the locus of the sol gene was determined to be -21.1 cM of the 6th linkage group. These results suggest that the 0.0 position of this linkage group should be the sol gene instead of the E loci. This inference was supported by the results of fluorescence in situ hybridization with an RNA probe derived from the B. mori Antennapedia gene closely linked with the E complex loci; the signal was detected at an internal region of a chromosome, not at its distal end.