A syntenic coding region for vitelline membrane proteins in four lepidopteran insects

The vitelline membrane is the inner layer of the eggshell, but the genomic information available for vitelline membrane proteins (VMPs) in Lepidoptera is limited. In the present study, we identified a syntenic coding region for VMPs in four lepidopteran genomes (Bombyx mori, Manduca sexta, Danaus plexippus and Heliconius melpomene) and four putative VMP coding genes located within it. RT-PCR results showed Bombyx VMP coding genes expressed prior to the early choriogenesis stage in follicles. Alignment analyses revealed that the vitelline membrane domain was shared between Lepidoptera and Diptera. However, the third cysteine residue conserved in dipteran VMPs was absent in those of Lepidoptera. In addition, another conserved region was identified in lepidopteran VMPs.