Archives of Insect Biochemistry and Physiology最新文献

The Chinese white wax scale insect (CWWSI), Ericerus pela, can secret an amount of wax equivalent to their body weight. Previous studies demonstrated the fatty acyl-CoA reductase (far3) plays a pivotal role in wax secretion of CWWSI. The high expression of far3 is crucial for the massive wax secretion. However, the transcription regulation of far3 was not clear. To identify regulatory factors that control the expression of far3, the assay for transposase-accessible chromatin (ATAC) and yeast one-hybrid (Y1H) were carried out in this study. The ATAC sequencing of the CWWSI at the early wax-secretion stage ATAC-seq resulted in 22.75 GB raw data, generated 75,827,225 clean reads and revealed 142,771 peaks. There was one significant peak in the 3 kb upstream regulation regions. The peak sequence is located between −1000 and −670 bp upstream of the far3 transcription start site, spanning a length of 331 bp. This peak sequence served as bait for creating the pAbAi-peak recombinant vector, used in Y1H screenings to identify proteins interacting with far3 gene. The results indicate a successful CWWSI cDNA library construction with a capacity of 1.2 × 10⁷ colony forming unit, a 95.8% recombination rate, and insert sizes between 1,000 and 2,000 bp. Self-activation tests established that 100 ng/mL of AbA effectively inhibited bait vector self-activation. Finally, a total of 88 positive clones were selected. After sequencing and removal of duplication, 63 unique clones were obtained from these screened colonies. By aligning the clone sequences with full-length transcriptome and genome of CWWSI, the full-length coding sequences of these clones were obtained. BlastX analysis identified a transcription factor, nuclear transcription factor Y beta, and two co-activators, cAMP-response-element-binding-protein-binding protein and WW domain binding protein 2. Reverse transcription quantitative polymerase chain reaction analysis confirmed that their expression patterns were consistent with the developmental stages preceding wax secretion and matched the wax secretion characteristics during ovulation periods. These results are beneficial for further research into the regulatory mechanisms of wax secretion of CWWSI.

Toll, immune deficiency and prophenoloxidase cascade represent vital immune signaling pathways in insects. Peptidoglycan recognition proteins (PGRPs) are innate immune receptors that activate and regulate the immune signaling pathways. Previously, we reported that BmPGPR-L4 was induced in the silkworm Bombyx mori larvae by bacteria and peptidoglycan challenges. Here, we focused on the function of BmPGRP-L4 in regulating the expression of antimicrobial peptides (AMPs). The hemolymph from BmPGRP-L4-silenced larvae exhibited an enhanced inhibitory effect on the growth of Escherichia coli, either by growth curve or inhibitory zone experiments. Coincidentally, most of the AMP genes were upregulated after RNAi of BmPGRP-L4. Oral administration of heat-inactivated E. coli and Staphylococcus aureus after RNAi of BmPGRP-L4 resulted in the increased expression of BmPGRP-L4 in different tissues of the silkworm larvae, revealing an auto-regulatory mechanism. By contrast, the expression of most AMP genes was downregulated by oral bacterial administration after RNAi of BmPGRP-L4. The above results demonstrate that BmPGRP-L4 recognizes bacterial pathogen-associated molecular patterns and negatively regulates AMP expression to achieve immunological homeostasis. As a negative regulator, BmPGPR-L4 is proposed to be involved in the feedback regulation of the immune signaling pathways of the silkworm to prevent excessive activation of the immune response.

Spodoptera frugiperda is a migratory agricultural pest with fast-spreading speed, long migration distance, and wide host range, which seriously threatens the safety of economic crops. To predict the trends of S. frugiperda and its parasitoid wasp Trichogramma pretiosum in their habitats under current and future climatic conditions, based on MaxEnt model and geographic distribution data of their historical occurrence, we project the feasibility of introducing T. pretiosum to control S. frugiperda by evaluating on their potential global distribution. The results show that, under the current greenhouse gas concentration, the potential distribution area of S. frugiperda is concentrated in 50° N-30° S, with a total area of 1.74 × 10⁶km², and the potential distribution area of T. pretiosum in the whole world is 2.91 × 10⁶km². The suitable areas of T. pretiosum cover almost all the suitable areas of S. frugiperda, which indicates that T. pretiosum can be introduced to control S. frugiperda. The results of this study can provide a theoretical basis for the monitoring and early warning of S. frugiperda and the use of T. pretiosum to control S. frugiperda.

The predatory stink bug Arma custos has been selected as an effective biological control agent and has been successfully massly bred and released into fields for the control of a diverse insect pests. As a zoophytophagous generalist, A. custos relies on a complex neuropeptide signaling system to prey on distinct food and adapt to different environments. However, information about neuropeptide signaling genes in A. custos has not been reported to date. In the present study, a total of 57 neuropeptide precursor transcripts and 41 potential neuropeptide G protein-coupled receptor (GPCR) transcripts were found mainly using our sequenced transcriptome data. Furthermore, a number of neuropeptides and their GPCR receptors that were enriched in guts and salivary glands of A. custos were identified, which might play critical roles in feeding and digestion. Our study provides basic information for an in-depth understanding of biological and ecological characteristics of the predatory bug and would aid in the development of better pest management strategies based on the effective utilization and protection of beneficial natural enemies.

Insecticide mode of action studies provide insights into how new insecticidal actives function and contribute to assessing safety to humans and nontarget organisms. Insect cell lines that express potential target sites can serve as valuable tools in this effort. In this paper, we report on the influence of two signaling molecules on protein expression in a nervous system cell line established from Spodoptera frugiperda (Bayer/BCIRL-SfNS2-0714-TR). We selected this line because we established it in our laboratory and we are experienced in using it. Cells were exposed to the insect developmental hormone (1 µg/mL 20-hydroxyecdysone, 20E) and/or a cyclooxygenase (COX) inhibitor (25 μM indomethacin, INDO; inhibits prostaglandin [PG] biosynthesis) for 24 h (Day 2), 72 h (Day 4), or 120 h (Day 6). We selected a PG biosynthesis inhibitor because PGs act in many aspects of insect biology, such as embryonic development, immunity, and protein phosphorylation. We selected the developmental hormone, 20E, because it also acts in fundamental aspects of insect biology. We identified specific proteins via in silico analysis. Changes in protein expression levels were determined using liquid chromatography-mass spectrometry (MS) + MS-MS. The largest number of changes in protein expression occurred on Day 2. The combination of 20E plus INDO led to 222 differentially expressed proteins, which documents the deep significance of PGs and 20E in insect biology. 20E and, separately, INDO led to changes in 30 proteins each (p value < 0.01; >2X or <0.5X-fold changes). We recorded changes in the expression of 9 or 12 proteins (20E), 10 or 6 proteins (INDO), and 21 or 20 proteins (20E + INDO) on D4 and D6, respectively. While the cell line was established from neuronal tissue, the differentially expressed proteins act in a variety of fundamental cell processes. In this paper, we moved beyond a list of proteins by providing detailed, Gene Ontology term analyses and enrichment, which offers an in-depth understanding of the influence of these treatments on the SfNS2 cells. Because proteins are active components of cell physiology in their roles as enzymes, receptors, elements of signaling transduction pathways, and cellular structures, changes in their expression levels under the influence of signaling molecules provide insights into their function in insect cell physiology.

Insects are covered with free neutral cuticular hydrocarbons (CHC) that may be linear, branched, and unsaturated and vary in their chain length. The CHC composition is species-specific and contributes to the adaptation of the animal to its ecological niche. Commonly, CHCs contribute substantially to the inward and outward barrier function of the cuticle and serve pheromonal communication. They are generally determined by gas-chromatography, a time-consuming method requiring detailed expertize, but it is not available in many laboratories. Here, we report on the establishment of a colorimetric method allowing semi-quantitative determination of unsaturated CHCs in Drosophila flies. This method is based on the in vitro reaction of vanillin with double bounds in lipid molecules in an acidic solution to generate a reddish color. We found a robust correlation between gas chromatographic and vanillin-colorimetric data on unsaturated CHCs amounts in single flies. As the role of unsaturated CHCs in the performance of insects in their environment is only partly understood, we think that this novel method would allow fast and broad analyses of this type of CHCs in insects both in the field and in laboratories and thereby contribute to a substantial improvement in the investigation of this matter.

Geranylgeranyl diphosphate synthase (GGPPS) as the short-chain prenyltransferases for catalyzing the formation of the acyclic precursor (E)-GGPP has been extensively investigated in mammals, plants, and microbes, but its functional plasticity is poorly understood in insect species. Here, a single GGPPS in leaf beetle Monolepta hieroglyphica, MhieGGPPS, was functionally investigated. Phylogenetic analysis showed that MhieGGPPS was clustered in one clade with homologs and had six conserved motifs. Molecular docking results indicated that binding sites of dimethylallyl diphosphate (DMAPP), (E)-geranyl pyrophosphate (GPP), and (E)-farnesyl pyrophosphate (FPP) were in the chain-length determination region of MhieGGPPS, respectively. In vitro, recombiant MhieGGPPS could catalyze the formation of (E)-geranylgeraniol against different combinations of substrates including isopentenyl pyrophosphate (IPP)/DMAPP, IPP/(E)-GPP, and IPP/(E)-FPP, suggesting that MhieGGPPS could not only use (E)-FPP but also (E)-GPP and DMAPP as the allylic cosubstrates. In kinetic analysis, the (E)-FPP was most tightly bound to MhieGGPPS than that of others. It was proposed that MhieGGPPS as a multifunctional enzyme is differentiated from the other GGPPSs in the animals and plants, which only accepted (E)-FPP as the allylic cosubstrate. These findings provide valuable insights into understanding the functional plasticity of GGPPS in M. hieroglyphica and the novel biosynthesis mechanism in the isoprenoid pathway.

The mitochondrial genome (mitogenome) of thrips is characterized by the presence of control region (CR) duplication. However, the evolution pattern of duplicated CRs in thrips is still unclear. In this study, the multiple independent origins of duplicated CR indicated that the CR duplication was not an ancestral state for Thysanoptera. The macroevolutionary pattern suggested that the earliest CR duplication event occurred in the middle Cretaceous (94.85 Ma) coincided with rearrangement events forming the ancestors of Aeolothripidae, but much later than that forming the ancestors of the suborder Terebrantia. The mitogenome with duplicated CRs showed a higher rate of gene rearrangement. The sequence similarity of the CR copies and divergence time were negatively correlated, indicating age-related deterioration of mitochondrial function. No significant differences were found in the mitochondrial DNA, the P₁₂₃ and P_4FD between the single and multiple-CR charactered mitogenomes, which suggested that the duplicated CRs may not affect the replication process in thrip mitogenome. The mitogenomes with duplicated CRs (mean: 0.0088 subs/s/my) show a significantly increased evolutionary rate than that with a single one (mean: 0.0058 subs/s/my). However, it seems that this higher evolutionary rate did not have adaptive mechanisms in Terebrantia. We speculated that the duplicated CRs may cause a more intense production of energy by mitochondria, and an accelerated mutation and substitution rate is expected in such mitogenomes. Our study provided new insights into the presence of CR duplications and their evolution in the mitogenomes of thrips.

Lipid storage in the form of triacylglycerol (TAG) is essential for insect life, as it enables flight, development, and reproduction. The activity of the lipase brummer (bmm) has been shown to be essential to insects' homeostasis. The objective of this study was to evaluate how bmm expression occurs in Aedes aegypti larvae and adults, and to observe TAG levels during fasting in adult females. The bmm sequence was identified in A. aegypti and exhibited a patatin-like phospholipase domain reinforced by the presence of a catalytic dyad with serine and aspartate residues, revealing a high degree of similarity with other organisms. Bmm expression was differentiated in the larvae and adult fat body (FB) following TAG reserve dynamics. Bmm was expressed three times in larval stages L3, L4, and pupae compared with L1 and L2, which could indicate its role in the maturation of these insects. In the postemergence (PE) and post-blood meal (PBM) FB of adult insects, bmm expression varied over several days. PE adults showed a pronounced bmm increase from the third day onward compared with those not subjected to fasting. This was accompanied by a decrease in TAG from the third day onward, suggesting the participation of bmm. Six hours after blood feeding, TAG levels increased in mosquitos reared in the absence of sucrose, suggesting lipid accumulation to guarantee reproduction. Bmm responded positively to fasting, followed by TAG mobilization in adult FB. During the previtellogenic period, bmm levels responded to low TAG levels, unlike the PBM period.

Bombyx mori bidensovirus (BmBDV) is one of the most important pathogens of silkworm. It mainly infects midgut cells of silkworm and causes losses to the sericulture industry. Long noncoding RNAs (lncRNAs) have been reported to play an important role in the regulation of antiviral immune response in silkworm. To explore whether lncRNAs are involved in BmBDV infection and immune response of silkworm, we performed a comparative transcriptome analysis to identify the lncRNAs and mRNAs between the BmBDV infected and noninfected silkworm larvae at the early stage. A total of 16,069 genes and 974 candidate lncRNAs were identified, among which 142 messenger RNA (mRNAs) and four lncRNAs were differentially expressed (DE). Target gene prediction revealed that 142 DEmRNAs were coexpressed with four DElncRNAs, suggesting that the expression of mRNA is mainly affected through trans-regulation activities. A regulatory network of DElncRNAs and DEmRNAs was constructed, showing that many genes targeted by different DElncRNAs are involved in metabolism and immunity, which implies that these genes and lncRNAs play an important role in the replication of BmBDV. Our results will help us to improve our understanding of lncRNA-mediated regulatory roles in BmBDV infection, providing a new perspective for further exploring the interaction between host and BmBDV.