Insect Molecular Biology最新文献

Exportin 1 (XPO1) is the major karyopherin-β nuclear receptor mediating the nuclear export of hundreds of proteins and some classes of RNA and regulates several critical processes in the cell, including cell-cycle progression, transcription and translation. Viruses have co-opted XPO1 to promote nucleocytoplasmic transport of viral proteins and RNA. Maize mosaic virus (MMV) is a plant-infecting rhabdovirus transmitted in a circulative propagative manner by the corn planthopper, Peregrinus maidis. MMV replicates in the nucleus of plant and insect hosts, and it remains unknown whether MMV co-opts P. maidis XPO1 (PmXPO1) to complete its life cycle. Because XPO1 plays multiple regulatory roles in cell functions and virus infection, we hypothesized that RNAi-mediated silencing of XPO1 would negatively affect MMV accumulation and insect physiology. Although PmXPO1 expression was not modulated during MMV infection, PmXPO1 knockdown negatively affected MMV accumulation in P. maidis at 12 and 15 days after microinjection. Likewise, PmXPO1 knockdown negatively affected P. maidis survival and reproduction. PmXPO1 exhibited tissue-specific expression patterns with higher expression in the ovaries compared with the guts of adult females. Survival rate was significantly lower for PmXPO1 knockdown females, compared with controls, but no effect was observed for males. PmXPO1 knockdown experiments revealed a role for PmXPO1 in ovary function and egg production. Oviposition and egg hatch on plants were dramatically reduced in females treated with dsRNA PmXPO1. These results suggest that PmXPO1 is a positive regulator of P. maidis reproduction and that it plays a proviral role in the insect vector supporting MMV infection.

REPAT (response to pathogen) is an immune-associated gene family that plays important roles in insect immune response to pathogens. Although nine REPAT genes have been identified in Spodoptera frugiperda (Lepidoptera: Noctuidae) currently, their functions and mechanisms in the immune response to pathogens still remain unclear. Therefore, SfREPAT38, a pathogen response gene (REPAT) of S. frugiperda, was characterised and its function was analysed. The results showed that SfREPAT38 contains a signal peptide and a transcription activator MBF2 (multi-protein bridging factor 2) domain. Quantitative real-time polymerase chain reaction analysis showed that SfREPAT38 was highly expressed in the sixth-instar larvae (L6) and was the highest in expression in the midgut of L6. We found that the expression of SfREPAT38 could be activated by challenge with four microbial pathogens (Bacillus thuringiensis, Metarhizium anisopliae, Spodoptera exigua nuclearpolyhedrosis and Escherichia coli), except 12 h after E. coli infection. Furthermore, the SfREPAT38 expression levels significantly decreased at 24, 48 and 72 h after SfREPAT38 dsRNA injection or feeding. Feeding with SfREPAT38 dsRNA significantly decreased the weight gain of S. frugiperda, and continuous feeding led to the death of S. frugiperda larvae from the fourth day. Moreover, SfREPAT38 dsRNA injection resulted in a significant decrease of weight gain on the fifth day. Silencing SfREPAT38 gene down-regulated the expression levels of immune genes belonging to the Toll pathway, including SPZ, Myd88, DIF, Cactus, Pell and Toll18W. After treatment with SfREPAT38 dsRNA, S. frugiperda became extremely sensitive to the B. thuringiensis infection, and the survival rate dramatically increased, with 100% mortality by the eighth day. The weight of S. frugiperda larvae was also significantly lower than that of the control groups from the second day onwards. In addition, the genes involved in the Toll signalling pathway and a few antibacterial peptide related genes were down-regulated after treatment. These results showed that SfREPAT38 is involved in the immune response of S. frugiperda larvae through mediating Toll signalling pathway.

The silkworm, Bombyx mori, is a complete metamorphosed economic insect, and the silk gland is a significant organ for silk protein synthesis and secretion. The silk gland completely degenerates during pupation, but the regulatory mechanism of programmed cell death (PCD) has not yet been understood. In the present study, we investigated the non-genetic pathway of 20E-induced PCD in the posterior silk gland (PSG) based on intracellular Ca²⁺ levels. Silk gland morphology and silk gland index indicated rapid degeneration of silk gland during metamorphosis from mature silkworm (MS) to pupal day 1 (P1), and Ca²⁺ levels within the PSG were found to peak during the pre-pupal day 1 (PP1) stage. Moreover, the results of autophagy and apoptosis levels within the PSG showed that autophagy was significantly increased in MS-PP1 periods, and significantly decreased in PP2 and P1 periods. Apoptosis was almost absent in MS-PP1 periods and significantly increased in PP2 and P1 periods. Additionally, western blotting results showed that autophagy preceded apoptosis, and the autophagy-promoting ATG5 was cleaved by calpain to the autophagy-inhibiting and apoptosis-promoting NtATG5 since PP1 period, while decreased autophagy was accompanied by increased apoptosis. Collectively, these findings suggest that Ca²⁺ is a key factor in the shift from autophagy to apoptosis.

The fluctuation in temperature poses a significant challenge for poikilothermic organisms, notably insects, particularly in the context of changing climatic conditions. In insects, temperature adaptation has been driven by polygenes. In addition to genes that directly affect traits (core genes), other genes (peripheral genes) may also play a role in insect temperature adaptation. This study focuses on two peripheral genes, the GRIP and coiled-coil domain containing 2 (GCC2) and karyopherin subunit beta 1 (KPNB1). These genes are differentially expressed at different temperatures in the cosmopolitan pest, Plutella xylostella. GCC2 and KPNB1 in P. xylostella were cloned, and their relative expression patterns were identified. Reduced capacity for thermal adaptation (development, reproduction and response to temperature extremes) in the GCC2-deficient and KPNB1-deficient P. xylostella strains, which were constructed by CRISPR/Cas9 technique. Deletion of the PxGCC2 or PxKPNB1 genes in P. xylostella also had a differential effect on gene expression for many traits including stress resistance, resistance to pesticides, involved in immunity, trehalose metabolism, fatty acid metabolism and so forth. The ability of the moth to adapt to temperature via different pathways is likely to be key to its ability to remain an important pest species under predicted climate change conditions.

Odorant-binding proteins (OBPs) initiate insect olfactory perception and mediate specific binding and selection of odorants via uncertain binding mechanisms. We characterized the binding characteristics of four OBPs from the striped flea beetle Phyllotreta striolata (SFB), a major cruciferous crop pest. Tissue expression analysis revealed that the two ABPII OBPs (PstrOBP12 and PstrOBP19) were highly expressed mainly in the antenna, whereas the two minus-C OBPs (PstrOBP13 and PstrOBP16) showed a broad expression pattern. Competitive binding assays of cruciferous plant volatiles showed that PstrOBP12, PstrOBP16 and PstrOBP19 had very strong binding capacities for only two phthalate esters (K_i < 20 μM), and PstrOBP13 specifically bound to four aromatic volatiles (K_i < 11 μM). Fluorescence quenching assays displayed that two phthalate esters bound to three PstrOBPs via different quenching mechanisms. PstrOBP12/PstrOBP16–diisobutyl phthalate and PstrOBP19–bis(6-methylheptyl) phthalate followed static quenching, while PstrOBP12/PstrOBP16–bis(6-methylheptyl) phthalate and PstrOBP19–diisobutyl phthalate followed dynamic quenching. Homology modelling and molecular docking displayed that PstrOBP12–diisobutyl phthalate was driven by H-bonding and van der Waals interactions, while PstrOBP16–diisobutyl phthalate and PstrOBP19–bis(6-methylheptyl) phthalate followed hydrophobic interactions. Finally, behavioural activity analysis demonstrated that phthalate esters exhibited different behavioural activities of SFB at different doses, with low doses attracting and high doses repelling. Overall, we thus revealed the different binding properties of the three PstrOBPs to two phthalate esters, which was beneficial in shedding light on the ligand-binding mechanisms of OBPs.

Insect Molecular Biology (IMB) publishes high-quality research related to the molecular biology of insects. We are a society journal, overseen by the Royal Entomological Society, which publishes IMB as part of its mission to enrich the world with insect science. Many of the IMB editors are also members of the Royal Entomological Society, working to support its mission. When you publish in or review for IMB, you are also supporting this mission.

IMB seeks to publish research on a variety of subjects in molecular biology using a range of model systems. Common topics are the molecular genetics of development, insecticide resistance, behaviour, neurobiology, sociality, reproduction, immunity, genomics, ecology, evolution and symbiont interactions. Focal insects include the models Drosophila and Tribolium, as well as a range of less-studied, but economically important insects. Importantly, IMB also considers manuscripts that focus on non-insect arthropods, such as ticks and spiders.

We say a reluctant good-bye and a hearty thank you to Dr. Mark Paine, who served in the Editor-in-Chief role for 6 years. We have a vibrant, diverse and high-profile global editorial board to ensure publication of high-quality original research and review articles. We are still keen to recruit new Associate Editors to the board, so please look out for recruitment opportunities coming up.

IMB is a strong supporter of transparency, scientific rigour and reproducibility, and we will shortly be requiring authors to deposit their data at the revision stage and make this available to editors and reviewers.

IMB welcomes both original research and review papers. Original research papers can be in long or short format. Please see the information under ‘Instructions for Authors’ to understand the distinction between the two. Review papers should be timely and should comprehensively review the focal field. For either submission type, the Editors-in-Chief and the Review Editor are happy to correspond regarding pre-submission inquiries.

IMB also welcomes proposals for special issues. Special issues are an excellent way to make a larger impact with your work. Wiley has support services in place to help Guest Editors through every stage of the process.

We particularly encourage submissions or special issue proposals that address the grand challenges in entomology (Luke et al., 2023). Methodological techniques came out strongly as a challenge as did conservation and anthropogenic impacts. Works addressing these areas and in scope for IMB are welcome.

Multiple Wolbachia strains can block pathogen infection, replication and/or transmission in Aedes aegypti mosquitoes under both laboratory and field conditions. However, Wolbachia effects on pathogens can be highly variable across systems and the factors governing this variability are not well understood. It is increasingly clear that the mosquito host is not a passive player in which Wolbachia governs pathogen transmission phenotypes; rather, the genetics of the host can significantly modulate Wolbachia-mediated pathogen blocking. Specifically, previous work linked variation in Wolbachia pathogen blocking to polymorphisms in the mosquito alpha-mannosidase-2 (αMan2) gene. Here we use CRISPR-Cas9 mutagenesis to functionally test this association. We developed αMan2 knockouts and examined effects on both Wolbachia and virus levels, using dengue virus (DENV; Flaviviridae) and Mayaro virus (MAYV; Togaviridae). Wolbachia titres were significantly elevated in αMan2 knockout (KO) mosquitoes, but there were complex interactions with virus infection and replication. In Wolbachia-uninfected mosquitoes, the αMan2 KO mutation was associated with decreased DENV titres, but in a Wolbachia-infected background, the αMan2 KO mutation significantly increased virus titres. In contrast, the αMan2 KO mutation significantly increased MAYV replication in Wolbachia-uninfected mosquitoes and did not affect Wolbachia-mediated virus blocking. These results demonstrate that αMan2 modulates arbovirus infection in A. aegypti mosquitoes in a pathogen- and Wolbachia-specific manner, and that Wolbachia-mediated pathogen blocking is a complex phenotype dependent on the mosquito host genotype and the pathogen. These results have a significant impact for the design and use of Wolbachia-based strategies to control vector-borne pathogens.

Frankliniella occidentalis (Pergande) is a typical omnivorous insect that feeds on host plants, pollens and mite eggs, and poses a threat to crops worldwide. The insulin signalling pathway (ISP) is a typical nutrient-sensitive pathway that participates in the regulation of various functions in insects. Serine/threonine kinases (AKTs) and phosphoinositide-dependent kinases (PDKs) are key components of the ISP. In this study, the FoAKT and FoPDK genes in F. occidentalis were cloned, and the effects of three foods on their expression were determined. The expression of FoAKT and FoPDK in the thrips fed on kidney bean leaves supplemented with pine pollen or mite eggs was higher than in those primarily fed on leaves alone. Meanwhile, the fecundity of thrips fed on leaves supplemented with pine pollen was highest. In addition, RNA interference-mediated knockdown of FoAKT and FoPDK decreased vitellogenin (Vg) content and Vg expression in females, shortened ovariole length, delayed egg development and reduced fecundity and offspring hatching rates. Furthermore, the synthesis of juvenile hormone (JH) was reduced, and the contents of glucose, trehalose, glycogen and trehalase were affected. These results suggest that FoAKT and FoPDK regulate the reproduction of F. occidentalis by regulating Vg and JH production as well as carbohydrate metabolism.

Fatty acyl-CoA reductase (FAR) is one of the key enzymes, which catalyses the conversion of fatty acyl-CoA to the corresponding alcohols. Among the FAR family members in the brown planthopper (Nilaparvata lugens), NlFAR7 plays a pivotal role in both the synthesis of cuticular hydrocarbons and the waterproofing of the cuticle. However, the precise mechanism by which NlFAR7 influences the formation of the cuticle structure in N. lugens remains unclear. Therefore, this paper aims to investigate the impact of NlFAR7 through RNA interference, transmission electron microscope, focused ion beam scanning electron microscopy (FIB-SEM) and lipidomics analysis. FIB-SEM is employed to reconstruct the three-dimensional (3D) architecture of the pore canals and related cuticle structures in N. lugens subjected to dsNlFAR7 and dsGFP treatments, enabling a comprehensive assessment of changes in the cuticle structures. The results reveal a reduction in the thickness of the cuticle and disruptions in the spiral structure of pore canals, accompanied by widened base and middle diameters. Furthermore, the lipidomics comparison analysis between dsNlFAR7- and dsGFP-treated N. lugens demonstrated that there were 25 metabolites involved in cuticular lipid layer synthesis, including 7 triacylglycerols (TGs), 5 phosphatidylcholines (PCs), 3 phosphatidylethanolamines (PEs) and 2 diacylglycerols (DGs) decreased, and 4 triacylglycerols (TGs) and 4 PEs increased. In conclusion, silencing NlFAR7 disrupts the synthesis of overall lipids and destroys the cuticular pore canals and related structures, thereby disrupting the secretion of cuticular lipids, thus affecting the cuticular waterproofing of N. lugens. These findings give significant attention with reference to further biochemical researches on the substrate specificity of FAR protein, and the molecular regulation mechanisms during N. lugens life cycle.

Although the study of many genes and their protein products is limited by the availability of high-quality antibodies, this problem could be solved by fusing a tag/reporter to an endogenous gene using a gene-editing approach. The type II bacterial CRISPR/Cas system has been demonstrated to be an efficient gene-targeting technology for many insects, including the oriental fruit fly Bactrocera dorsalis. However, knocking in, an important editing method of the CRISPR/Cas9 system, has lagged in its application in insects. Here, we describe a highly efficient homology-directed genome editing system for B. dorsalis that incorporates coinjection of embryos with Cas9 protein, guide RNA and a short single-stranded oligodeoxynucleotide donor. This one-step procedure generates flies carrying V5 tag (42 bp) in the BdorTRH gene. In insects, as in other invertebrates and in vertebrates, the neuronal tryptophan hydroxylase (TRH) gene encodes the rate-limiting enzyme for serotonin biosynthesis in the central nervous system. Using V5 monoclonal antibody, the distribution of TRH in B. dorsalis at different developmental stages was uncovered. Our results will facilitate the generation of insects carrying precise DNA inserts in endogenous genes and will lay foundation for the investigation of the neural mechanisms underlying the serotonin-mediated behaviour of B. dorsalis.