Insect Molecular Biology最新文献

In insects, eye pigmentation is vital for various adaptive functions, including foraging, mating and predator avoidance. Due to its visible and often heritable variation, altered eye pigmentation in mutants provides an excellent model for studying biosynthetic pathways and identifying new genes involved in pigmentation. Eye mutants can also be valuable in science communication as they offer simplified examples to help the public understand complex genetic concepts. In this study, we used a community science-based approach to identify the inheritance pattern and mutation(s) responsible for white-eye pigmentation in honey bees. With the help of the beekeeping community, we identified a honey bee queen that produced a fraction of haploid sons (called drones) with white-eyes. As the queen was wild-type, we predicted that the mutation is most likely recessive to wild-type. Using genome-wide association and differentiation scans of wild-type and white-eyed drone brothers, we identified a single elevated region (52 kb) of chromosome 11. This region contains four non-coding RNA (ncRNA) and one protein-coding gene. We identified an eight-base pair region with two SNPs and a four-nucleotide deletion that are likely responsible for the phenotype. The mutation likely affects the expression and/or downstream effects of an uncharacterized ncRNA (LOC100578475). Our efforts highlight the value of community-based science in novel gene discovery. We hope this serves, not only as a new example for the burgeoning field of honey bee functional genomics, but also as a teaching tool for both researchers and educators.

Diapause is a crucial biological adaptation that enables many insects to endure unfavourable environmental conditions and maintain species survival. The silkworm, Bombyx mori, a classic model organism exhibiting embryonic diapause, provides an excellent system for investigating diapause mechanisms. In this study, we evaluated the effectiveness of electrical stimulation in terminating diapause and explored its underlying regulatory mechanisms during the termination process in silkworms. Specifically, electrical stimulation significantly improved the economic traits of silkworms compared to HCl treatment. Transcriptome sequencing was performed to analyse dynamic gene regulation during diapause termination following electrical stimulation in two silkworm strains: the Chinese lineage strain Qiufeng and the Japanese lineage strain Baiyu. Gene ontology (GO) enrichment analysis of differentially expressed genes (DEGs) revealed, for the first time, that the mechanism of diapause termination in silkworms is lineage-specific. Weighted gene co-expression network analysis (WGCNA) further indicated that this lineage-specific diapause release is primarily driven by the differential expression of genes involved in the carbohydrate biosynthesis pathway. These findings both validate the practical application of electrical stimulation in sericulture and reveal fundamental differences in diapause regulation between silkworm lineages, advancing our understanding of this crucial biological process.

Moulting and metamorphosis are fundamental physiological processes in the growth and development of holometabolous insects, primarily regulated by ecdysteroids and juvenile hormone (JH), which are synthesized and secreted by the prothoracic gland and corpora allata, respectively. However, the signalling regulatory network involved in the synthesis of these hormones and their effects is complex and interactive and involves many unidentified functional genes. In this study, we conducted a basic bioinformatics analysis of the CAD96CA gene and obtained CAD96CA mutants at the individual level in domestic silkworms using the CRISPR-Cas9 technology. We analysed the growth, development and silk protein synthesis phenotypes of the mutants and detected the synthesis and signalling effects of 20E and JH. The results revealed that knocking out the CAD96CA gene resulted in inhibited larval growth, reduced silk protein production, hindered larval-pupal transition and led to larval mortality. The synthesis of 20E and its signalling pathways, as well as the signalling pathways of JH, were all affected to varying degrees following CAD96CA knockout. Our study elucidates the role of CAD96CA in the growth and development of silkworms and provides a reference for studying metamorphosis mechanisms.

Liang, L.N., Zhang, L.L., Zeng, B.J., Zheng, S.C. & Feng, Q.L. (2015) Transcription factor CAAT/enhancer-binding protein is involved in regulation of expression of sterol carrier protein x in Spodoptera litura. Insect Molecular Biology, 24(5), 551–560. Available from: https://doi.org/10.1111/imb.12182.

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During Drosophila spermatogenesis, mitochondria undergo elongation along the entire length of the spermatid tail, thereby establishing a structural framework that facilitates microtubule reorganization and the synchronized individualization of spermatids. This process ultimately culminates in the production of functional, mature sperm. Despite this understanding, the regulatory mechanisms governing elongation and individualization remain largely unexplored. The gene ζTrypsin encodes a member of the serine protease enzyme family. However, its molecular function remains to be elucidated. In this study, we elucidated the critical role of ζTrypsin in the process of spermatid individualization. In ζTrypsin knockdown testes, spermatid individualization complexes with F-actin cones were either entirely absent or disrupted, leading to an absence of mature sperm in the seminal vesicle and resulting in reduced male fertility. The most significant effects included reduced tubulin polyglycylation and disrupted mitochondrial function. Transcriptome analysis identified 1878 differentially expressed genes, with 814 genes upregulated and 1064 genes downregulated. These findings suggest that ζTrypsin is essential for spermatid maturation by influencing mitochondrial morphogenesis.

Lytic polysaccharide monooxygenases (LPMOs) that are capable of oxidative cleavage of glycosidic bonds in crystalline polysaccharides including chitin and cellulose are widely distributed among organisms. Insect LPMOs belong to auxiliary activity family 15 (LPMO15/AA15) and have been classified further into at least four subgroups. However, unlike LPMOs from microorganisms and viruses, their physiological functions in insects have not been well studied. In the present work, we investigated the functions of two group I LPMO15s, MaLPMO15-1 and PhLPMO15-1, in chitinous cuticle turnover during moulting of two important forest pest longhorn beetles-the Japanese pine sawyer beetle, Monochamus alternatus, and the yellow spotted longicorn beetle, Psacothea hilaris. Real-time qPCR showed a similar pattern of expression of MaLPMO15-1 and PhLPMO15-1 during late stages of development with high levels present at young pharate pupal and young pupal stages and declining thereafter. Injection of double-stranded RNA (dsRNA) for MaLPMO15-1 (dsMaLPMO15-1) or PhLPMO15-1 (dsPhLPMO15-1) into last instar larvae of M. alternatus and P. hilaris, respectively, did not affect subsequent larval-pupal moulting and the resulting pupae exhibited normal development. However, the pupae were unable to eclose to the adult stage and died entrapped inside their old pupal cuticle. TEM analysis revealed that, unlike the respective dsRNA for the enhanced green fluorescent protein (dsEGFP)-treated control insects, both dsMaLPMO15-1- and dsPhLPMO15-1-treated pharate adults failed to degrade the endocuticular layer of their pupal cuticle in which the horizontal chitinous laminae remained largely intact. These results demonstrate that the group I LPMO15-1 enzymes play a role in pupal cuticle chitin turnover, which is critical for moulting to the adult. Because LPMO15-1 is highly conserved among many insect species, this gene/enzyme is a potential target for the control of populations of both M. alternatus and P. hilaris as well as other pest insect species.

Throughout their evolution, insects have become specialised to occupy diverse ecological niches. The carrot weevil, Listronotus oregonensis, is an important agricultural pest that exhibits a very specific host range. In this study, we characterised the genome and transcriptomes of each developmental stage of L. oregonensis and its Wolbachia endosymbiont to gain deeper knowledge of the genetic determinants controlling its biology. We annotated 14,637 genes and showed expression profiles across the developmental stages. We also compared orthologous genes between L. oregonensis and nine other species, with particular focus on chemoreceptors and detoxification genes. We identified 24 distinct odorant-binding protein genes and 41 genes for receptors involved in stimulus perception, relatively low numbers compared with other species, which would be consistent with a narrow host range. In contrast, we found a high number of detoxification genes, with significant expansion of certain gene families. Among the annotated genes, 46 were putatively acquired through horizontal gene transfer, with 17 showing strong evidence for this, including several cell-wall degrading enzymes. The phylogeny of a cytolethal distending toxin gene also suggests an initial transfer from a prokaryotic source and vertical dissemination in members of Curculionidae through recent evolution. The presence of the endosymbiotic bacterium Wolbachia (supergroup A) was confirmed in all tested L. oregonensis individuals from several regions in northeastern North America and showed very little diversity. This study enhances our understanding of the genomic, functional, and evolutionary aspects of a significant agricultural pest and makes important and useful databases available to the scientific community.

The response of insects to stress, particularly starvation and high temperature stress, is a crucial area of insect research. Uridine diphosphate-glucosyltransferases (UGTs) are key enzymes involved in the detoxification of exogenous substances. This study analysed the role of the UGT344J7 gene in the response of Rhopalosiphum padi to starvation and high temperature stress. UGT344J7 was significantly upregulated under conditions of high temperature and food scarcity. Following RNAi targeting UGT344J7, the mortality of R. padi increased significantly under both high temperature and starvation conditions. Knockdown of the UGT344J7 gene led to a significant increase in reactive oxygen species (ROS) levels in R. padi, accompanied by a significant downregulation of four heat shock protein genes (Hsp70-1, Hsp70-2, Hsp68, Hsp90). Based on these results, we speculate that UGT344J7 regulates the expression of heat shock protein genes by modulating ROS levels, thereby helping R. padi cope with high temperature and starvation stress. This is the first report on the role of the UGT gene in starvation and high temperature stress in an aphid species. This research suggests that silencing UGT344J7 could serve as a potential strategy for controlling R. padi, and novel insecticides targeting this gene may be developed to disrupt the physiological processes of this significant pest.

Bioluminescence (BL) in the Keroplatinae subfamily (Diptera: Keroplatidae) is found in Keroplatus, Neoceroplatus and Orfelia fultoni larvae. In O. fultoni, BL involves an oligomeric luciferase, a luciferin called keroplatin, which is associated with a substrate binding fraction (SBF), whose molecular identity and function remain uncertain. Non-luminescent web-constructing predatory larvae of Neoditomyia sp. (Keroplatinae) also contain keroplatin and SBF in their bodies, suggesting additional unknown roles for this compound in this subfamily. To identify gene products differentially expressed between luminescent and non-luminescent larvae, especially those associated with luciferase, SBF and keroplatin synthesis, here we compared the transcriptional and proteomic profiles of Neoditomyia sp., O. fultoni and Arachnocampa larvae and conducted biochemical assays. Similarly to O. fultoni, Neoditomyia sp. displays an abundance of hexamerin isoforms and transcripts associated with the tryptophan and kynurenine pathway, which is potentially involved with keroplatin synthesis and silk production. Despite displaying a similar electrophoretic pattern of Orfelia luciferase purified fractions, no luciferase activity was detected in Neoditomyia purified fractions. The SBF-enriched fractions from O. fultoni and Neoditomyia revealed a similar abundance of hexamerins, the presence of flavin-dependent reductases, keroplatin and riboflavin. The results indicate that the SBF consists of protein aggregates associated with riboflavin and keroplatin, which is used as luciferin in bioluminescent species and for other still unveiled physiological functions in non-luminescent species.

Behavioural manipulation techniques, particularly attractants, have been widely adopted as environmentally friendly approaches to manage Bactrocera dorsalis. These approaches primarily target odorant receptors (ORs), key molecular components in the pest's chemotactic pathways, to guide pests towards traps or lethal stimuli, offering a sustainable and effective alternative to chemical pesticides. However, pest behaviour extends beyond chemotaxis. Crucial behaviours such as mating, oviposition and defence also directly influence population dynamics, underscoring the need to investigate molecular targets that regulate diverse behavioural processes. IR25a, a co-receptor of ionotropic receptors (IRs), exhibits functional versatility by detecting diverse signals, including both volatile and non-volatile compounds and environmental cues (e.g., temperature, humidity, acidity). These characteristics make IR25a a promising candidate target that influences various behavioural processes. In this study, CRISPR/Cas9 was employed to generate a BdorIR25a knockout homozygous strain (BdorIR25a^-/-). Its effects on various aspects of pest behaviour were systematically investigated to evaluate its potential as a molecular target for behavioural modification. Results showed that BdorIR25a was highly expressed in pupal and adult stages, particularly in antennae and mouthparts. Knockouts exhibited impaired responsiveness to specific chemicals, especially dimethylamine. Additionally, mutants displayed reduced courtship wing vibration, pheromone responsiveness and mating success. Oviposition rates and egg-laying numbers were significantly reduced in females. Importantly, knockouts had no detectable effects on growth or survival, confirming BdorIR25a's primary role in behavioural modification. In conclusion, our findings identify BdorIR25a as a key molecular target with strong potential for manipulating diverse behavioural processes, providing a new perspective for pest control strategies. Future studies should focus on identifying IR25a-associated IRs and other molecular targets within its linked regions to clarify their respective roles in modulating critical behavioural traits. These studies could provide detailed insights into the molecular mechanisms of behaviour manipulation, advancing the development of innovative and targeted pest control strategies.