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At present, the effect of ultraviolet (UV) radiation on the interaction between Bombyx mori nucleopolyhedrovirus (BmNPV) and host remains unclear. In the current study, UV treatment significantly reduced the activity of BmNPV budded viruses (BVs), and UV-damaged BmN cells were not conducive to BmNPV proliferation. BmNPV infection significantly reduced the viability of host cells, but increased the viability of high-dose UV-treated host cells. Furthermore, the quantitative reverse-transcription PCR (qPCR) results suggested that BmNPV and Bombyx mori might mutually use the same DNA repair proteins for repairing UV-induced damage and BmNPV infection promote the ability of host cells to repair UV-induced damage., (© 2019 Wiley Periodicals, Inc.)

Insect cuticle acts as a primary protective barrier against environment stresses that may directly impact the insect body. Here, we report the mechanical defense function of a structural cuticular protein, BmorCPH24, to environmental stresses using a silkworm Bamboo (Bo) mutant with this gene mutation. Ultraviolet (UV) irradiation and topical application of an acetone insecticide were used as environmental stresses to determine the differences in susceptibility between Bo and wild-type larvae. UV irradiation resulted in a sunburn phenotype in the Bo strains earlier than the wild-type indicating the sensitivity of Bo. Higher malondialdehyde (MDA) content and a lower survival ratio were also observed in the Bo strains. Treatment with deltamethrin revealed that Bo larvae were more sensitive to insecticides than the wild-type. Furthermore, cuticle analysis by microsection revealed thinner cuticle and a significant decrease in the endocuticle layer (∼64.0%) in Bo. These results suggest that BmorCPH24 mutation can lead to deficiency in resources required to construct the cuticle in Bo resulting in thin cuticle and reduced resistance to UV and insecticides. These results provide us new insight into the role of structural cuticular proteins in insect cuticle against environment stresses., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Speckled (Spc), an X-ray-induced lethal mutant of Bombyx mori, exhibits a mosaic dark-brown-spotted larval epidermis in both sexes and egg-laying problems only in females. Here, we report the morphological characterization and molecular mapping of the Spc mutant. Morphological investigations revealed that the epidermal ultrastructure of the small, dark-brown spots was more dense than that of the white regions in both Spc/+ mutants and wild type, and that the lethality of the Spc/Spc mutants occurred during early embryogenesis. Furthermore, the ovarioles and ovipositor were disconnected in approximately 85.5% of Spc/+ females, a further 2.5% had a connection between the ovarioles and ovipositor that was too narrow to lay eggs. The remaining females showed a normal connection similar to that of the wild type. We successfully narrowed down the location of the Spc mutation to a region on chromosome 4 that was ∼1041 kb long. Gene-prediction analysis identified 25 candidate genes in this region. Chromosome structure analysis indicated that a ∼305 kb deletion was included in the mapping region. Temporal and spatial reverse transcription PCR (RT-PCR) analysis showed that several genes in the mapped region are associated with the Spc mutant. Although the genes responsible for the Spc mutation were not definitively identified, our results further the current understanding of the complex mechanism underlying the multiple morphological defects in Spc mutants., (© 2015 The Royal Entomological Society.)