Polymorphism and linkage analysis of the prothoracicotropic hormone gene in the silkmoth,Bombyx mori

Abstract
Summary: We looked for polymorphism of the prothoracicotropic hormone gene locus (Ptth) among inbred strains of the silkmoth,Bombyx mori, by invitroDNA amplification (polymerase chain reaction), and found three alleles,PtthA,PtthBandPtthC. ThePtthAallele contained a third intron consisting of 680 bp and a fourth intron of 350 bp.PtthBcontained the same size third intron but a longer fourth intron of 490 bp, while Ptthc had a longer third intron of 1080 bp and a shorter fourth intron of 350 bp. In 29 strains which we examined, 9 strains hadPtthA, 8 strains hadPtthB, and 2 strains had Ptthc. The other 10 strains had heterogeneous genotypes with the same 3 alleles.