Characterization of a Gene Encoding KK-42-Binding Protein in Antheraea pernyi (Lepidoptera: Saturniidae)

Abstract

Abstract KK-42 is an imidazole insect growth regulator. A (KK-42)-binding protein (KK-42BP) has been shown to be associated with diapause termination in pharate first instars of Antheraea yamamai (Guérin-Méneville) (Lepidoptera: Saturniidae). In this study, the (KK-42)-binding protein gene (ApKK-42BP) was characterized from Antheraea pernyi (Guérin-Méneville) (Lepidoptera: Saturniidae) undergoing a winter diapause as a pupa. Homologous comparison revealed that KK-42BPs from A.pernyi and A.yamamai were closely related to the known minor yolk proteins from the lepidopterans Bombyx mori L., Plodia interpunctella (Hübner), and Galleria mellonella L. The two KK-42BPs also contained a lipase-like region, as observed in the known lepidopteran yolk proteins. Phylogenetic analysis suggested that KK-42BP is a new member of the minor yolk proteins. Reverse transcription-polymerase chain reaction analyses showed that ApKK-42BP mRNA was expressed in all of the tissues tested, throughout four developmental stages, and in both female and male. Both in the brain and hemolymph, expression of ApKK-42BP mRNA level was similar between nondiapause-destined and diapause-destined larval individuals. ApKK-42BP mRNA was expressed in the predia-pause period of diapause-destined pupae, disappeared in early diapause and diapause stage, and reappeared in the postdiapause stage. These expression patterns stated that a lack of KK-42BP is associated with pupal diapause and its expression may be critical to nondiapausing individuals. Our results suggested that the KK-42BP gene is likely involved in a function other than as a yolk protein.