Insect Molecular Biology最新文献

Urbanisation alters the environment of organisms, creating new challenges and opportunities. In ants, urbanisation has been shown to increase resistance to temperature and to pollutants. Here we assessed how urbanisation affects gene expression in workers and queens of the ant Temnothorax nylanderi, a species that inhabits both city and forest habitats. We further examined whether there was a differential expression between two distinct conditions, in the field or after laboratory rearing for 8 months. As expected, the number of differentially expressed genes (DEGs) between workers and queens was large (2830 genes). However, we found that habitat (city or forest) had no clear influence on gene expression in queens and workers of T. nylanderi even when individuals were directly collected from the field. Interestingly, we also found 661 DEGs between field colonies and laboratory-reared ones. The effect of rearing conditions on gene activity was greater in workers than in queens, suggesting that queens are more resilient to environmental changes. The lack of transcriptional differences between habitats is intriguing because of the previously observed differences in life-history traits between city and forest populations.

The genome of Triatoma rubrofasciata, a representative of the North American Triatomini lineage, was analysed to characterise its repetitive DNA content and satellite DNA (satDNA) organisation. Using RepeatExplorer2, we determined that repetitive elements comprise approximately 25% of the genome in a male sample from Vietnam and 16% in a female sample from China, with satDNA being the most abundant component. The satellitome analysis revealed 126 satDNA families in the male and 114 in the female, with marked quantitative differences driven by the amplification of two satDNA families: TrubSat001-166 and TrubSat002-9. Fluorescence in situ hybridization (FISH) confirmed that TrubSat002-9 is enriched in the Y chromosome, explaining its lesser abundance in the female genome. Chromosomal mapping revealed three distribution patterns of satDNA: (i) localisation in autosomal heterochromatin, (ii) restriction to the Y chromosome, and (iii) presence in euchromatin. SatDNA landscapes showed sharp peaks at low divergence values, consistent with recent amplifications in heterochromatic regions, and broader peaks at higher divergence levels, suggesting older satDNAs located in euchromatic regions. Additionally, several satDNA families are conserved among T. rubrofasciata, T. infestans, T. delpontei and Rhodnius prolixus, supporting the “library hypothesis” of satDNA evolution. Our findings highlight the differential amplification of satDNA families linked to heterochromatin expansion, particularly in autosomes, and the conservation of Y-linked repeats. This study provides new insights into the dynamic role of satDNAs in the karyotypic evolution of Triatominae bugs.

Copper (Cu), a trace element with crucial roles in physiological processes, can exert detrimental effects when imbalanced. Despite growing research on Cu's impacts on biota, its effects on terrestrial organisms, particularly insects, at environmental concentrations remain poorly understood. This study aims to elucidate the mechanisms underlying Cu-induced damage in silkworms (Bombyx mori L., 1758 (Lepidoptera: Bombycidae)) and identify potential targets to mitigate such damage. Using an integrated approach of physiological, histopathological, biochemical and multi-omics analyses, we investigated the effects of Cu exposure throughout most of the silkworms' larval stage. Our findings reveal that Cu exposure significantly hampers the growth and development of silkworms, evidenced by reduced intestinal trehalose levels, compromised peritrophic membrane (PM) structure in the midgut (MG) and altered composition and diversity of the intestinal microbiota. Furthermore, Cu exposure leads to an increase in pathogenic bacteria and a decrease in probiotics and induces inflammation and apoptosis in the midgut and fatbody (FB) tissues. Biochemical and transcriptomic analyses indicate that Cu disrupts nutrient metabolism and energy homeostasis, resulting in decreased adenosine triphosphatase (ATP) levels. Chronic Cu exposure activates the PI3K/AKT/mTOR signalling pathway, triggering abnormal apoptosis and autophagy, altering detoxification processes, immune enzyme activities and gene expression. This study provides novel insights into the mechanisms of Cu toxicity in silkworms and establishes a foundation for identifying targets to reduce Cu's biotoxicity, offering valuable data for managing Cu pollution in insects.

Over time, populations of Apis cerana across diverse geographical regions have undergone distinct phenotypic adaptations in response to varied climates, arising from prolonged natural evolutionary processes. Understanding the molecular genetic underpinnings and the implications of climate change on the adaptive evolution of A. cerana is crucial for its conservation amidst environmental shifts. Here, we conducted a comprehensive analysis of 110 bee individuals sourced from 11 regions at comparable temperatures, environments, and altitudes. A total of 525.56 Gb of filter-trimmed sequencing data were utilised for population genetic analysis of honeybees. The findings indicate genetic differentiation among bee populations from various geographical regions, with higher levels of population divergence observed in different altitudinal environments. Particularly noteworthy is the significant genetic divergence of the bee population from Haikou (HK) compared to populations in other areas, characterised by higher inbreeding coefficients and runs of homozygosity (ROHs), as well as lower nucleotide diversity. However, populations from Guangzhou (GZ), Jinzhai (JZ), Qimen (QM), Shennongjia (SNJ), and Suzhou (SZ) exhibit a close genetic relationship. Using comparisons across multiple bee populations from different groups, we identified selective signatures across different environmental temperatures and altitudes. Furthermore, by integrating genomic selection signals with comparative transcriptomic analysis, we identified genes potentially involved in bee adaptation to high altitude, such as g9950.t1 (alcohol dehydrogenase), g5267.t1 (diacylglycerol kinase theta-like isoform 2), gene g4025.t1 (Tyrosine 3-monooxygenase), and g3609.t1 (heme oxygenase). Our results indicate that both temperature and altitude contribute to the genetic differentiation and geographical adaptability of A. cerana populations.

Antimicrobial peptides (AMPs) are increasingly being recognised as promising alternatives to conventional antibiotics due to their distinctive antimicrobial mechanisms and reduced likelihood of inducing drug resistance. Insects represent a significant source of AMPs. In this study, a potential AMP gene, MdAMP5, was identified based on its strong immunoinducibility and the presence of a signal peptide, and an amphipathic α-helix in the encoded protein. MdAMP5 encoded a 50-amino acid precursor protein with an N-terminal 22-amino acid signal peptide. The calculated molecular mass of the mature protein was 2.92 kDa, with an estimated isoelectric point of 6.23. Structural analyses revealed that the N-terminus of mature MdAMP5 contained an irregularly coiled segment, while the C-terminus featured an amphipathic α-helix with a glycine-lysine residue at the end. Furthermore, the MdAMP5 gene was successfully expressed in the yeast Pichia pastoris, and the recombinant MdAMP5 (rMdAMP5) protein exhibited effective and broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria in vitro and in vivo. Treatment with rMdAMP5 resulted in significant changes in bacterial morphology, including cell lysis and deformation of bacteriophages. In conclusion, this study identified and successfully expressed a novel AMP that showed low cytotoxicity to mammalian cells and high selectivity towards bacterial cells. This research offers a new candidate for therapeutic drug development, and enhances the understanding of the mechanism and application of AMPs.

Bombyx mori is an economically crucial lepidopteran insect, and its health is closely related to the gut microbiota and metabolic status. Our previous research confirmed that metal–organic frameworks nanocomposite ZIF8@ZIF67 supplementation can significantly enhance silkworm survival rates upon bacterial challenges without adversely affecting its growth or cocoon weight. To elucidate the mechanism, this study integrated non-targeted metabolomics and 16S rRNA sequencing to dissect ZIF8@ZIF67-driven midgut modulations. The results showed that ZIF8@ZIF67 supplementation led to significant metabolic shifts in the midgut of B. mori, with 96 metabolites up-regulated and 54 down-regulated in the negative ion model, and 117 up-regulated and 43 down-regulated in the positive ion model. Key pathways included glutathione metabolism, purine/pyrimidine metabolism, and histidine metabolism, which are involved in antioxidant defence, nucleotide and protein synthesis for growth and immunity regulation. Furthermore, the gut microbiota composition of B. mori was significantly altered after ZIF8@ZIF67 supplementation, with a marked increase in the relative abundance of Mammaliicoccus and Enterococcus. Lastly, the correlation between metabolites and microbiomes was analysed, including Enterococcus and 1-methylhistidine (r = 0.8895, p = 0.0001), Akkermansia and N-acetyl-d-galactosamine (r = 0.8674, p = 0.0003). These findings demonstrated that ZIF8@ZIF67 could optimise silkworm health by orchestrating metabolite-microbe interactions to enhance nutrient assimilation and oxidative stress resilience, while simultaneously activating pathways essential for growth regulation and immune function.

Malpighian tubules (MTs) of insects are integral to osmoregulation, detoxification, immunity and stress responses. Cicadas experience an ecological transition from subterranean to aboveground during ontogeny. However, little is known about the morphological/functional differences related to MTs between their nymphal and adult stages and potential molecular mechanisms underlying the transition. We described morphological changes of MTs from nymph to adult, including more elongated and densified microvilli and drastically dissolved secretory vacuoles. These alterations indicate MTs functionally transitioned from multifunctional secretory organs in nymphs to primarily excretory organs in adults. Transcriptomic analyses revealed differentially expressed genes were related to osmoregulation, energy metabolism, detoxification, immunity and protein synthesis, etc., across developmental stages. The upregulation of genes involved in ion transport and energy metabolism in adults suggests that enhanced capabilities for rapid waste excretion and energy acquisition are essential for aboveground adults. Increased expression of detoxification and immune-related genes indicates evolutionary adaptations of MTs to manage dietary toxicity and bolster defence mechanisms in adults. These adaptations facilitate the transition from subterranean nymphs to aboveground adults and enhance cicadas' ability to thrive in diverse ecological niches. Our findings infer the role of hormonal regulation in facilitating functional modifications of MTs to adult emergence during cicadas' growth and development. Results of this study have important implications for the evolution of life-history strategy of insects responding to diet/habitat changes during ontogeny. These findings enhance our understanding of how insects adapt to dietary/habitat shift and emphasise the importance of MTs in physiological responses to environmental challenges.

The microRNAs (miRNAs) play an important role in the regulation of gene expression, influencing the outcome of many biological processes in insects. The introduction of miRNA into the insect body can lead to pest developmental abnormalities indicating that miRNAs are potential targets for pest control. In this study, we employed small RNA sequencing to characterise and analyse the expression of miRNAs in the sugarcane shoot borer Chilo infuscatellus (Snellen). By integrating previously published transcriptome sequencing data, we predicted and identified miRNAs and their target genes involved in the ecdysone metabolic pathway. We confirmed the target relationships between Ci-miR-4, Ci-miR-5 and CiCYP18A1 by RT-qPCR and dual-luciferase reporter assays in vivo and in vitro. Additionally, injection of miRNA mimics reduced the transcripts of CiCYP18A1 and led to abnormal moulting, which is similar to the defect phenotype of depletion of CiCYP18A1 by dsRNA. Furthermore, we also mixed the synthesised Ci-miR-5 mimic into artificial diets and found similar stunting results of the injection method. These results demonstrated that Ci-miR-5 could target CiCYP18A1 to regulate the moulting process and the successful use of an insect miRNA for gene silencing studies in this sugarcane pest. The method provided an effective novel approach for future RNAi-based pest control strategies.

Cyantraniliprole (Cya), a diamide insecticide, is widely utilised for the management of Lepidoptera pests owing to its potent insecticidal efficacy and broad spectrum of activity. The extensive use and prolonged environmental persistence of this insecticide pose a significant threat to the sustainable development of sericulture. This study firstly assessed the lethal toxicity of cyantraniliprole to the 5th instar larvae of Bombyx mori. Exposure to cyantraniliprole (LC₅, LC₁₀ and LC₂₀) resulted in a concentration-dependent reduction in larval weight, pupal weight and survival rate and a prolongation of larval development time. Moreover, cyantraniliprole LC₁₀ resulted in substantial structural damage to the epithelial cells, suppressed the mRNA levels of oxidative phosphorylation genes, perturbed ATP synthesis and led to an imbalance of intracellular reactive oxygen species. Meanwhile, the starvation treatment suggested that the impacts of cyantraniliprole on silkworms cannot be solely ascribed to nutritional deficiencies. Additionally, the results revealed that cytochrome P450s might serve as a pivotal factor in the detoxification metabolism of cyantraniliprole in the midgut of silkworms. The findings of this study offer evidence for the ecological risk posed by environmental residues of cyantraniliprole to non-target organisms and are also of great significance for sericulture production.

Mealybugs are highly aggressive pests that infest various plants and cause substantial economic losses. Histone lysine methyltransferases (KMT) are evolutionarily conserved and proposed to be essential in early embryo development in animals. However, few KMTs have been reported in mealybugs. Here, we identified a novel KMT gene, PsASH2, in the cotton mealybug, Phenacoccus solenopsis Tinsley. This gene was highly expressed in the ovary of female adults. Through RNA interference (RNAi) of PsASH2 by dsRNA microinjection, we found a reduction in the number of male embryos and total embryos in the ovaries of pregnant females. Continuous downregulation of PsASH2 in mated females until their death resulted in few changes in sex ratio but significant decreases in the number of both male and female offspring. Therefore, we believe that PsASH2 plays essential roles in embryo survival for both sexes of the cotton mealybug which may provide a potential target gene for the management of cotton mealybug by disrupting embryo development.