Development and formation of wing cuticle based on transcriptomic analysis in Locusta migratoria during metamorphosis

Wings are an important flight organ of insects.Wing development is a complex process controlled by a series of genes.The flightless wing pad transforms into a mature wing with the function of migratory flight during the nymphto-adult metamorphosis.However,the mechanism of wing morphogenesis in locusts is still unclear.This study analyzed the microstructures of the locust wing pads at pre-eclosion and the wings after eclosion and performed the comparative transcriptome analysis.RNA-seq identified 25,334 unigenesand 3,430 differentially expressed genes(DEGs)(1,907 up-regulated and 1,523 down-regulated).The DEGs mainly included cuticle development(LmACPs),chitin metabolism(Lm Idgf4),lipid metabolism-related genes,cell adhesion(Integrin),zinc finger transcription factors(LmSalm,LmZF593 andLmZF521),and others.Functional analysis based on RNA interference and hematoxylin and eosin(H&E)staining showed that the three genes encoded zinc finger transcription factors are essential for forming wing cuticle and maintaining morphology in Locusta migratoria.Finally,the study found that the LmSalm regulates the expression of LmACPs in the wing pads at pre-eclosion,and LmZF593 and LmZF521 regulate the expression of LmIntegrin/LmIdgf4/LmHMT420 in the wings after eclosion.This study revealed that the molecular regulatory axis controls wing morphology in nymphal and adult stages of locusts,offering a theoretical basis for the study of wing development mechanisms in hemimetabolous insects.

Juvenile hormone membrane signaling phosphorylates USP and thus potentiates 20-hydroxyecdysone action in Drosophila

Juvenile hormone(JH) and 20-hydroxyecdysone(20 E) coordinately regulate development and metamorphosis in insects. Two JH intracellular receptors, methoprene-tolerant(Met) and germ-cell expressed(Gce), have been identified in the fruit fly Drosophila melanogaster. To investigate JH membrane signaling pathway without the interference from JH intracellular signaling, we characterized phosphoproteome profiles of the Met gce double mutant in the absence or presence of JH in both chronic and acute phases.Functioning through a potential receptor tyrosine kinase and phospholipase C pathway, JH membrane signaling activated protein kinase C(PKC) which phosphorylated ultraspiracle(USP) at Ser35, the PKC phosphorylation site required for the maximal action of 20 E through its nuclear receptor complex Ec RUSP. The usp;mutant, in which Ser was replaced with Ala at position 35 by genome editing, showed decreased expression of Halloween genes that are responsible for ecdysone biosynthesis and thus attenuated 20 E signaling that delayed developmental timing. The usp;mutant also showed lower Yorkie activity that reduced body size. Altogether, JH membrane signaling phosphorylates USP at Ser35 and thus potentiates 20 E action that regulates the normal fly development. This study helps better understand the complex JH signaling network.