摘要: Transcription factor Broad Complex (BR-C) is an ecdysone primary response gene in insects and participates in the regulation of insect growth and development. In this study, we performed a genome-wide identification of BR-C target genes in silkworm (Bombyx mori) using chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq). As a result, a total of 1006 BR-C ChIP peaks were identified, and 15% of peaks were located in the promoter regions of 133 protein-coding genes. Functional annotation revealed that these ChIP peak-associated genes, as potential BR-C targets, were enriched in pathways related to biosynthetic process, metabolic process, and development. Transcriptome analysis and quantitative real-time polymerase chain reaction (PCR) examination revealed that developmental changes in expression patterns of a portion of potential BR-C targets, including HR96 and GC-alpha 1, were similar to those of BR-C. ChIP-PCR examination confirmed that BR-C could directly bind to the promoters of potential targets. Further, dual luciferase assays demonstrated that HR96 promoter activity was significantly upregulated following BR-C overexpression, and this upregulation was abolished when the binding motif in the promoter was truncated. This study will be helpful for deciphering the regulatory roles of BR-C during insect growth and development.

摘要: Wing polymorphism significantly contributes to the ecological success of some insect species. For example, the brown planthopper (BPH)Nilaparvata lugens, which is one of the most destructive rice pests in Asia, can develop into either highly mobile long-winged or highly fecund short-winged adult morphs. A recent study reported a highly provocative result that theHoxgeneUltrabithorax(Ubx) is expressed in BPH forewings and showed that this wing development gene is differentially expressed in nymphs that develop into long-winged versus short-winged morphs. Here, we found thatUbxmay be amir-9atarget, and used dual luciferase reporter assays and injected micro RNA (miRNA) mimics and inhibitors to confirm the interactions betweenmir-9aandNlUbx. We measured themir-9aandNlUbxexpression profiles in nymphs and found that the expression of these two biomolecules was negatively correlated. By rearing BPH nymphs on host rice plants with different nutritional status, we were able to characterize a regulatory cascade between insulin receptor genes,mir-9a, andNlUbxthat regulate wing length in BPHs. When host quality was low,NlInR1expression in the nymph terga increased andNlInR2expression decreased; this led to a highermir-9alevel, which in turn reduced theNlUbxtranscript level and ultimately resulted in longer wing lengths. Beyond extending our understanding of the interplay between host plant status and genetic events that modulate polymorphism, we demonstrated both the upstream signal and miRNA-based regulatory mechanism that controlUbxexpression in BPH forewings.

摘要: Long non-coding RNAs (lncRNAs) are poorly understood in insects. In this study, we performed genome-wide analysis of lncRNAs inTribolium castaneumby RNA-seq. In total, 4516 lncRNA transcripts corresponding to 3917 genes were identified from late embryos, early larvae, late larvae, early pupae, late pupae and early adults ofT. castaneum, including 3152 novel lncRNAs and 1364 known lncRNAs. These lncRNAs have few exons and transcripts, and are short in length. During development, they exhibited nine different expression patterns. Functionally, they can act either by targeting messenger RNAs (1813 lncRNAs) and lncRNAs (45 lncRNAs) or as micro RNA (miRNA) precursors (46 lncRNAs). LncRNAs were observed to target the metabolic enzymes of glycolysis, TCA cycle and amino acids, demonstrating that lncRNAs control metabolism by regulating metabolic enzymes. Moreover, lncRNAs were shown to participate in cell differentiation and development via their targets. As miRNA precursors, lncRNAs could participate in the ecdysone signaling pathway. This study provides comprehensive information for lncRNAs ofT. castaneum, and will promote functional analysis and target identification of lncRNAs in the insect.

摘要: Mermithid nematodes, such asOvomermis sinensis, are used as biological control agents against many insect pests, including cotton bollworm (Helicoverpa armigera). However, given the host's robust immune system, the infection rate ofO.sinensisis low, thus restricting its widespread use. To understand the host defense mechanisms against mermithid nematodes, we identified and characterized a protein involved in the recognition ofO.sinensis, the potentialO.sinensis-binding protein C-type lectin 1 (HaCTL1a and/or HaCTL1b), which was eluted from the surface ofO. sinensisafter incubation withH.armigeraplasma. HaCTL1b is homologous to the previously reported HaCTL1a protein. HaCTL1 was predominantly expressed in hemocytes and was induced by the steroid hormone 20-hydroxyecdysone through ecdysone receptor (HaEcR) or ultraspiracle (HaUSP), or both. Binding assays confirmed the interactions of the HaCTL1 proteins withO.sinensisbut not withRomanomermis wuchangensis, a parasitic nematode of mosquito. Moreover, the HaCTL1 proteins were secreted into the hemocoel and promoted hemocyte-mediated encapsulation and phagocytosis. A knockdown of HaEcR and/or HaUSP resulted in compromised encapsulation and phagocytosis. Thus, HaCTL1 appears to modulate cellular immunity in the defense against parasitic nematodes, and the 20-hydroxyecdysone-HaEcR-HaUSP complex is involved in regulating the process.

摘要: Carboxylesterases (CarEs) represent one of the major detoxification enzyme families involved in insecticide resistance. However, the function of specific CarE genes in insecticide resistance is still unclear in the insectNilaparvata lugens(Stal), a notorious rice crop pest in Asia. In this study, a total of 29 putative CarE genes inN. lugenswere identified, and they were divided into seven clades; further, the beta-esterase clade was significantly expanded. Tissue-specific expression analysis found that 17 CarE genes were abundantly distributed in the midgut and fat body, while 12 CarE genes were highly expressed in the head. The expression of most CarE genes was significantly induced in response to the challenge of nitenpyram, triflumezopyrim, chlorpyrifos, isoprocarb and etofenprox. Among these, the expression levels ofNlCarE2,NlCarE4,NlCarE9,NlCarE17andNlCarE24were increased by each insecticide. Real-time quantitative polymerase chain reaction and RNA interference assays revealed theNlCarE1gene to be a candidate gene mainly involved in nitenpyram resistance, while simultaneously silencingNlCarE1andNlCarE19produced a stronger effect than silencing either one individually, suggesting a cooperative relationship in resistance formation. These findings lay the foundation for further clarification of insecticide resistance mediated by CarE inN. lugens.