8.a.226. The Dusky-like (Dyl) Family
Dusky-like is critical for morphogenesis of the cellular protuberances and formation of the cuticle in Henosepilachna vigintioctopunctata (Zhang et al. 2023). Dyl is a transmembrane protein (2 TMSs, N- and C-terminal) containing a zona pellucida domain. Its physiological roles during metamorphosis have been well explored in Drosophila melanogaster and have also been documented in Tribolium castaneum. However, Dyl has undergone a functional shift between Diptera and Coleoptera insects. H. vigintioctopunctata is an important Coleoptera that causes enormous economic losses in agriculture in China. Zhang et al. 2023 found that the expression of Hvdyl was detectable in embryos, larvae, prepupae, pupae, and adults. RNA interference (RNAi) of Hvdyl mainly caused two phenotypic defects. Firstly, the growth of epidermal cellular protuberances was suppressed. Injection of dsdyl (double-stranded dusky-like RNA) at the third-instar larval stage truncated the scoli throughout the thorax and abdomen and shortened the setae on the head capsules and mouthparts of the fourth-instar larvae. Introduction of dsdyl at the third- and fourth-instar stages led to misshapen pupal setae. The setae were shortened or became black nodules. Treatment with dsdyl at the larval and pupal stages resulted in deformed adults with completely suppressed wing hairs. Moreover, the knockdown of Hvdyl at the third-instar stage caused deformed larval mouthparts at the fourth-instar period. As a result, foliage consumption was inhibited, and larval growth was slowed. This obsrvation indicate that Dyl is associated with the growth of cellular protuberances throughout development and with the formation of the cuticle in H. vigintioctopunctata (Zhang et al. 2023).