Fine structure of the compound eyes of the crepuscular moth Grapholita molesta (Busck 1916) (Lepidoptera: Tortricidae).

Morphological organization, ultrastructure and adaptational changes under different light intensities (10000, 100, 1, and 0.01 mW/m2) of the compound eye of the oriental fruit moth Grapholita molesta (Busck 1916) were investigated. Its superposition type of eyes consist of approximately 1072 ommatidia in males and 1029 ommatidia in females with ommatidial diameters of around 15 µm. Each ommatidium features a laminated corneal lens densely covered by corneal nipples of 256 nm in height. Crystalline cones are formed by four cone cells, proximally tapering to form a narrow crystalline tract with a diameter of 1.5 µm. Eight retinula cells, two primary and six secondary pigment cells per ommatidium are present. The 62.3 µm long rhabdom is divided into a thin 1.8 µm wide distal and a 5.2 µm wide proximal region. Distally the fused rhabdom consists of the rhabdomeres of seven retinula cells (R1-R7) and connects with the crystalline cone. In the proximal rhabdom region, the pigment-containing retinula cell R8 occupies a position in centre of the rhabdom while R1-R7 cells have taken peripheral positions. At this level each ommatidial group of retinula cells is surrounded by a tracheal tapetum. In response to changes from bright-light to dim-light adaptations, the pigment granules in the secondary pigment cells and retinula cells migrate distally, with a decrease in the length of crystalline tract.

Stellate ganglion block alleviates postoperative cognitive dysfunction via inhibiting TLR4/NF-κB signaling pathway.

Postoperative cognitive dysfunction (POCD) is common in aged patients after major surgery and is associated with increased risk of long-term morbidity and mortality. However, the underlying mechanism remains largely unknown and the clinical management of POCD is still controversial. Stellate ganglion block (SGB) is a clinical treatment for nerve injuries and circulatory issues. Recent evidence has identified the benefits of SGB in promoting learning and memory. We thus hypothesize that SGB could be effective in improving cognitive function after surgery. In present study, we established POCD model in aged rats via partial liver resection surgery. We found that the development of POCD was associated with the activation of toll-like receptor 4/nuclear factor kapa-B (TLR4/NF-κB) signaling pathway in the microglia in dorsal hippocampus, which induced the production of pro-inflammatory mediators (TNF-α, IL-1ß, IL-6) and promoted neuroinflammation. More importantly, we showed evidence that preoperative treatment with SGB could inhibit microglial activation, suppress TLR4/NF-κB-mediated neuroinflammation and effectively attenuate cognitive decline after the surgery. Our study suggested that SGB may serve as a novel treatment to prevent POCD in elderly patients. As SGB is safe procedure widely used in clinic, our findings can be easily translated into clinical practice and benefit more patients.

Biological potential of Bacillus subtilis BS45 to inhibit the growth of Fusarium graminearum through oxidative damage and perturbing related protein synthesis.

Fusarium root rot (FRR) caused by Fusarium graminearum poses a threat to global food security. Biological control is a promising control strategy for FRR. In this study, antagonistic bacteria were obtained using an in-vitro dual culture bioassay with F. graminearum. Molecular identification of the bacteria based on the 16S rDNA gene and whole genome revealed that the species belonged to the genus Bacillus. We evaluated the strain BS45 for its mechanism against phytopathogenic fungi and its biocontrol potential against FRR caused by F. graminearum. A methanol extract of BS45 caused swelling of the hyphal cells and the inhibition of conidial germination. The cell membrane was damaged and the macromolecular material leaked out of cells. In addition, the mycelial reactive oxygen species level increased, mitochondrial membrane potential decreased, oxidative stress-related gene expression level increased and oxygen-scavenging enzyme activity changed. In conclusion, the methanol extract of BS45 induced hyphal cell death through oxidative damage. A transcriptome analysis showed that differentially expressed genes were significantly enriched in ribosome function and various amino acid transport pathways, and the protein contents in cells were affected by the methanol extract of BS45, indicating that it interfered with mycelial protein synthesis. In terms of biocontrol capacity, the biomass of wheat seedlings treated with the bacteria increased, and the BS45 strain significantly inhibited the incidence of FRR disease in greenhouse tests. Therefore, strain BS45 and its metabolites are promising candidates for the biological control of F. graminearum and its related root rot diseases.

A female-biased odorant receptor tuned to the lepidopteran sex pheromone in parasitoid Microplitis mediator guiding habitat of host insects.

INTRODUCTION: The parasitoid wasp Microplitis mediator is an important natural enemy of the turnip moth Agrotis segetum and other Noctuidae pests. In our field observation, it was fortuitously discovered that sex pheromone traps used for A. segetum also attract female wasps, verified by a simulated field condition dual-choice laboratory assay. Therefore, it was hypothesized that olfactory recognition could be crucial in this process. In this regard, a female-biased odorant receptor of the wasp, MmedOR49, attracted our attention. OBJECTIVES: To unravel the significance of the female-biased MmedOR49 regulating host pheromone recognition. METHODS: Expression analysis (fluorescence in situ hybridization; quantitative realtime PCR), in vitro (two-electrode voltage-clamp recordings) and in vivo (RNAi combined with behavioral assessments) functional studies, and bioinformatics (structural modeling and molecular docking) were carried out to investigate the characteristics of MmedOR49. RESULTS: MmedOR49 expression was detected in the antennae of females by FISH. Quantification indicated that the expression level of MmedOR49 increased significantly after adult emergence. In vitro functional study revealed that MmedOR49 was specifically tuned to cis-5-decenyl acetate (Z5-10:Ac), the major sex pheromone component of A. segetum. Molecular docking showed that Z5-10:Ac strongly bound to the key amino acid residues His 80, Ile 81, and Arg 84 of MmedOR49 through hydrogen bonding. Behavioral assays indicated that female wasps were significantly attracted by Z5-10:Ac in a three-cage olfactometer. RNAi targeting further confirmed that MmedOR49 was necessary to recognize Z5-10:Ac, as female wasps lost their original behavioral responses to Z5-10:Ac after down-regulation of the MmedOR49 transcript. CONCLUSION: Although M. mediator is a larval endoparasitoid, female wasps have a behavioral preference for a sex pheromone component of lepidopteran hosts. In this behavior, for female M. mediator, MmedOR49 plays an important role in guiding the habitat of host insects. These data provide a potential target for enhancing natural enemy utilization and pest control.

Plant volatile ligands for male-biased MmedOBP14 stimulate orientation behavior of the parasitoid wasp Microplitis mediator.

As an important class of chemosensory-associated proteins, odorant binding proteins (OBPs) play a key role in the perception of olfactory signals for insects. Parasitoid wasp Microplitis mediator relies on its sensitive olfactory system to locate host larvae of Noctuidae and Geometridae. In the present study, MmedOBP14, a male-biased OBP in M. mediator, was functionally investigated. In fluorescence competitive binding assays, the recombinant MmedOBP14 showed strong binding abilities to five plant volatiles: ß-ionone, 3,4-dimethylacetophenone, 4-ethylacetophenone, acetophenone and ocimene. Homology modeling and molecular docking results indicated that the binding sites of all five ligands were similar and concentrated in the binding pocket of MmedOBP14. Except acetophenone, the remaining four ligands at 1, 10 and 100 µg/µL caused strong antennal electrophysiological responses in adults M. mediator, and males showed more obvious EAG responses to most ligands than females. In behavioral trials, males were attracted by low concentrations of MmedOBP14 ligands, whereas high doses of ß-ionone and acetophenone had a repellent effect on males. Moreover, 1 µg/µL of 3,4-dimethylacetophenone showed the strongest attractiveness to female wasps. These findings suggest that MmedOBP14 may play a more important role in the perception of plant volatiles for male wasps to locate habitat, supplement nutrition and search partners.

Comparison of superior and inferior vena cava diameter variation measured with transthoracic echocardiography to predict fluid responsiveness in mechanically ventilated patients after abdominal surgery.

BACKGROUND: The volume status of patients after major abdominal surgery constantly varies owing to postoperative diverse issues comprising fluid loss or capillary leakage secondary to systemic inflammatory reaction syndrome, et.al, the precise fluid responsiveness assessment is crucial for those patients. The purpose of this study is to validate the transthoracic ultrasonographic measurement of superior and inferior vena cava variation in predicting fluid responsiveness of mechanically ventilated patients after surgery. METHODS: A total of 70 patients undergoing the scheduled major abdominal surgeries in the anesthesia ICU ward were included. The superior vena cava (SVC) collapsibility index (SVCCI), the inferior vena cava distensibility index (dIVC), SVC variation over the cardiac cycle (SVCV), and cardiac output (CO) were measured by transthoracic ultrasonography were recorded before and after fluid challenge test of 5 ml/kg crystalloid within 15 min. The responders were defined as a 15% or more increment in CO. RESULTS: Thirty patients (42.9%) responded to fluid challenge, while the remnant forty patients (57.1%) did not. The areas under the ROC curve (AUC) of SVCCI, dIVC and SVCV were 0.885 (95% CI, 0.786-0.949; P < 0.0001) and 0.727 (95% CI, 0.608-0.827; P < 0.001) and 0.751 (95% CI, 0.633-0.847; P < 0.0001), respectively. AUCdIVC and AUCSVCV were significantly lower when compared with AUCSVCCI (P < 0.05). The optimal cutoff values were 19% for SVCCI, 14% for dIVC, and 15% for SVCV. The gray zone for SVCCI was 20%-25% and included 15.7% of patients, while 7%-27% for dIVC including 62.9% of patients and 9%-21% for SVCV including 50% of patients. CONCLUSION: Superior vena cava-related parameters measured by transthoracic ultrasound are reliable indices to predict fluid responsiveness. The accuracy of SVCCI in mechanically ventilated patients after abdominal surgery is better than that of dIVC and SVCV. TRIAL REGISTRATION: ChiCTR-INR-17013093 . The initial registration date was 24/10/2017.

Propofol protects cardiomyocytes from doxorubicin-induced toxic injury by activating the nuclear factor erythroid 2-related factor 2/glutathione peroxidase 4 signaling pathways.

Propofol offers important protective effects in ischemia/reperfusion-induced cardiomyocyte injury, but its specific mechanisms in doxorubicin (DOX)-induced cardiotoxicity have not been investigated. In this paper, we attempted to explore the effects of propofol on DOX-induced human cardiomyocyte injury and its related mechanisms. H9c2 cell viability was assessed by cell counting kit-8 and lactate dehydrogenase assay kit. Nuclear factor erythroid 2-related factor 2 (NRF2)/glutathione peroxidase 4 (GPx4) signaling pathway-related protein levels were measured by Western blot. Ferroptosis was evaluated by corresponding kits and Western blot and apoptosis was detected by CCK-8, terminal deoxynucleotidyl transferase dUTP nick-end labeling and Western blot. Oxidative stress was assessed by reactive oxygen species kit and the commercial kits, and inflammation response was analyzed by enzyme-linked immunosorbent assay and Western blot. The results showed that propofol attenuated DOX-induced cytotoxicity and activated Nrf2/GPx4 signaling pathways in H9c2 cells. In addition, propofol also alleviated DOX-induced ferroptosis, increased cell viability and inhibited apoptosis, oxidative stress and inflammatory responses in H9c2 cells through activation of Nrf2/GPx4 signaling pathways. In summary, propofol provides the protection against DOX-induced cardiomyocyte injury by activating Nrf2/GPx4 signaling, providing a new approach and theoretical basis for the repair of cardiomyocytes.

The complete mitochondrial genome of Conaspidia wangi Wei, 2015 (Hymenoptera: Tenthredinidae) and its phylogenetic analysis.

The mitochondrial genome of Conaspidia wangi Wei, 2015 was described. The total length of the sequence was 15,924 bp. The overall A + T content was 80.4%. In comparison with the ancestral organization, trnG was reversed and translocated between the AT-rich region and trnQ, which was reported for the first time in Symphyta. The downstream gene order of the AT-rich region were thus arranged as trnG-trnQ-trnM-trnI.

Characterization and target gene analysis of microRNAs in the antennae of the parasitoid wasp Microplitis mediator.

MicroRNAs (miRNAs), a class of non-coding single-strand RNA molecules encoded by endogenous genes, are about 21-24 nucleotides long and are involved in the post-transcriptional regulation of gene expression in plants and animals. Generally, the types and quantities of miRNAs in the different tissues of an organism are diverse, and these divergences may be related to their specific functions. Here we have identified 296 known miRNAs and 46 novel miRNAs in the antennae of the parasitoid wasp Microplitis mediator by high-throughput sequencing. Thirty-three miRNAs were predicted to target olfactory-associated genes, including odorant binding proteins (OBPs), chemosensory proteins, odorant receptors (ORs), ionotropic receptors (IRs) and gustatory receptors. Among these, 17 miRNAs were significantly highly expressed in the antennae, four miRNAs were highly expressed both in the antennae and head or wings, while the remaining 12 miRNAs were mainly expressed in the head, thorax, abdomen, legs and wings. Notably, miR-9a-5p and miR-2525-3p were highly expressed in male antennae, whereas miR-1000-5p and novel-miR-13 were enriched in female antennae. The 17 miRNAs highly expressed in antennae are likely to be associated with olfaction, and were predicted to target one OBP (targeted by miR-3751-3p), one IR (targeted by miR-7-5p) and 14 ORs (targeted by 15 miRNAs including miR-6-3p, miR-9a-5p, miR-9b-5p, miR-29-5p, miR-71-5p, miR-275-3p, miR-1000-5p, miR-1000-3p, miR-2525-3p, miR-6012-3p, miR-9719-3p, novel-miR-10, novel-miR-13, novel-miR-14 and novel-miR-28). These candidate olfactory-associated miRNAs are all likely to be involved in chemoreception through the regulation of chemosensory gene expression in the antennae of M. mediator.

Remimazolam benzenesulfonate anesthesia effectiveness in cardiac surgery patients under general anesthesia.

BACKGROUND: Sedation with propofol injections is associated with a risk of addiction, but remimazolam benzenesulfonate is a comparable anesthetic with a short elimination half-life and independence from cell P450 enzyme metabolism. Compared to remimazolam, remimazolam benzenesulfonate has a faster effect, is more quickly metabolized, produces inactive metabolites and has weak drug interactions. Thus, remimazolam benzenesulfonate has good effectiveness and safety for diagnostic and operational sedation. AIM: To investigate the clinical value of remimazolam benzenesulfonate in cardiac surgery patients under general anesthesia. METHODS: A total of 80 patients who underwent surgery in the Department of Cardiothoracic Surgery from August 2020 to April 2021 were included in the study. Using a random number table, patients were divided into two anesthesia induction groups of 40 patients each: remimazolam (0.3 mg/kg remimazolam benzenesulfonate) and propofol (1.5 mg/kg propofol). Hemodynamic parameters, inflammatory stress response indices, respiratory function indices, perioperative indices and adverse reactions in the two groups were monitored over time for comparison. RESULTS: At pre-anesthesia induction, the remimazolam and propofol groups did not differ regarding heart rate, mean arterial pressure, cardiac index or volume per wave index. After endotracheal intubation and when the sternum was cut off, mean arterial pressure and volume per wave index were significantly higher in the remimazolam group than in the propofol group (P < 0.05). After endotracheal intubation, the oxygenation index and the respiratory index did not differ between the groups. After endotracheal intubation and when the sternum was cut off, the oxygenation index values were significantly higher in the remimazolam group than in the propofol group (P < 0.05). Serum interleukin-6 and tumor necrosis factor-α levels 12 h after surgery were significantly higher than before surgery in both groups (P < 0.05). The observation indices were re-examined 2 h after surgery, and the epinephrine, cortisol and blood glucose levels were significantly higher in the remimazolam group than in the propofol group (P < 0.05). The recovery and extubation times were significantly lower in the remimazolam group than in the propofol group (P < 0.05); there were significantly fewer adverse reactions in the remimazolam group (10.00%) than in the propofol group (30.00%; P < 0.05). CONCLUSION: Compared with propofol, remimazolam benzenesulfonate benefited cardiac surgery patients under general anesthesia by reducing hemodynamic fluctuations. Remimazolam benzenesulfonate influenced the surgical stress response and respiratory function, thereby reducing anesthesia-related adverse reactions.

Molecular characterization and expression of sensory neuron membrane proteins in the parasitoid Microplitis mediator (Hymenoptera: Braconidae).

Sensory neuron membrane proteins (SNMPs), homologs of the human fatty acid transport protein CD36 family, are observed to play a significant role in chemoreception, especially in detecting sex pheromone in Drosophila and some lepidopteran species. In the current study, two full-length SNMP transcripts, MmedSNMP1 and MmedSNMP2, were identified in the parasitoid Microplitis mediator (Hymenoptera: Braconidae). Quantitative real-time polymerase chain reaction analysis showed that the expression of MmedSNMP1 was significantly higher in antennae than in other tissues of both sexes. In addition, the MmedSNMP1 transcript was increased dramatically in newly emerged adults and there were no significant differences between adults with or without mating and parasitic experiences. However, compared with MmedSNMP1, the expression of MmedSNMP2 was widely found in various tissues, significantly increased at half-pigmented pupae stage and remained at a relatively constant level during the following developmental stages. It was found that MmedSNMP1 contained eight exons and seven introns, which was highly conserved compared with other insect species. In situ hybridization assay demonstrated that MmedSNMP1 transcript was distributed widely in antennal flagella. Among selected chemosensory genes (odorant binding protein, odorant receptor, and ionotropic receptor genes), MmedSNMP1 only partially overlapped with MmedORco in olfactory sensory neurons of antennae. Subsequent immunolocalization results further indicated that MmedSNMP1 was mainly expressed in sensilla placodea of antennae and possibly involved in perceiving plant volatiles and sex pheromones. These findings lay a foundation for further investigating the roles of SNMPs in the chemosensation of parasitoids.

Antennal ionotropic receptors IR64a1 and IR64a2 of the parasitoid wasp Microplitis mediator (Hymenoptera: Braconidate) collaboratively perceive habitat and host cues.

Ionotropic receptors (IRs), as a member of the conserved chemoreceptor families in the peripheral nervous system, play a critical role in the chemoreception of Drosophila. However, little is known about IRs in Hymenoptera insects. Here, we comprehensively characterized the gene structure, topological map and chemosensory roles of antennal IRs (MmedIRs) in the hymenopteran parasitoid wasp Microplitis mediator. We found that the IRs were conserved across various insect species. In the in situ hybridization assays, most IRs showed female antennae biased features, and there was no co-expression of the IRs and the olfactory receptor co-receptor (ORco). Moreover, three IR co-expressed complexes, IR75u-IR8a, IR64a1-IR8a and IR64a2-IR8a, were detected. Two genes with high similarity, IR64a1 and IR64a2, were located in distinct neurons but projected to the same sensillum. In two-electrode voltage-clamp recordings, IR64a1 was widely tuned to the chemicals from habitat cues released from host plants over long distances, whereas IR64a2 responded to a narrow range host cues and plant odors with low-volatility. Notably, IR64a2 was able to perceive Z9-14: Ald, a vital sex pheromone component that is released from Helicoverpa armigera, which is the preferred host of M. mediator. Furthermore, most ligands of IR64a1 and IR64a2 can trigger electrophysiological responses in female wasps. We propose that IR64a1 and IR64a2 collaboratively perceive habitat and host cues to assist parasitoids in efficiently seeking hosts.

Insights into the venom protein components of Microplitis mediator, an endoparasitoid wasp.

Endoparasitoid wasps deliver a variety of maternal factors, such as venom proteins, viruses, and virus-like particles, from their venom and calyx fluid into hosts and thereby regulate the hosts' immune response, metabolism and development. The endoparasitoid, Microplitis mediator, is used as an important biological agent for controlling the devastating pest Helicoverpa armigera. In this study, using an integrated transcriptomic and proteomic analysis approach, we identified 75 putative venom proteins in M. mediator. The identified venom components were consistent with other known parasitoid wasps' venom proteins, including metalloproteases, serine protease inhibitors, and glycoside hydrolase family 18 enzymes. The metalloprotease and serpin family showed extensive gene duplications in venom apparatus. Isobaric tags for relative and absolute quantitation (iTRAQ) based quantitative proteomics revealed 521 proteins that were differentially expressed at 6 h and 24 h post-parasitism, including 10 wasp venom proteins that were released into the host hemolymph. Further analysis indicated that 511 differentially expressed proteins (DEP) from the host are primarily involved in the immune response, material metabolism, and extracellular matrix receptor interaction. Taken together, our results on parasitoid wasp venoms have the potential to enhance the application of endoparasitoid wasps for controlling insect pest.

A Metalloprotease Homolog Venom Protein From a Parasitoid Wasp Suppresses the Toll Pathway in Host Hemocytes.

Parasitoid wasps depend on a variety of maternal virulence factors to ensure successful parasitism. Encapsulation response carried out by host hemocytes is one of the major host immune responses toward limiting endoparasitoid wasp offspring production. We found that VRF1, a metalloprotease homolog venom protein identified from the endoparasitoid wasp, Microplitis mediator, could modulate egg encapsulation in its host, the cotton bollworm, Helicoverpa armigera. Here, we show that the VRF1 proenzyme is cleaved after parasitism, and that the C-terminal fragment containing the catalytic domain enters host hemocytes 6 h post-parasitism. Furthermore, using yeast two-hybrid and pull-down assays, VRF1 is shown to interact with the H. armigera NF-κB factor, Dorsal. We also show that overexpressed of VRF1 in an H. armigera cell line cleaved Dorsal in vivo. Taken together, our results have revealed a novel mechanism by which a component of endoparasitoid wasp venom interferes with the Toll signaling pathway in the host hemocytes.

Cryo-EM structure reveals cylindrical nucleocapsids from two polydnaviruses.

Bracovirus is one of the two polydnavirus genera. Here, we used a cryo-EM analysis to reveal the near-native morphology of two nucleocapsid-containing model bracoviruses: Microplitis bicoloratus bracovirus (MbBV) and Microplitis mediator bracovirus (MmBV). MbBV and MmBV nucleocapsids have discernable cap structures in two distal regions with relatively high electron density. Adjacent to the end-cap structures are two electron-lucent rings. Some nucleocapsids were uniformly electron-dense and had a distinctive "helix-tail-like structure". Cryo-EM revealed inconsistent nucleocapsid diameters of 34-69.9 nm in MbBV and 46-69.9 nm in MmBV, and the largest observed cylindrical area length was expanded to 126 nm.

Characterization of antennal chemosensilla and associated odorant binding as well as chemosensory proteins in the parasitoid wasp Microplitis mediator (Hymenoptera: Braconidae).

Odorant binding proteins (OBPs) and chemosensory proteins (CSPs) expressed in antennal chemosensilla are believed to be important in insect chemoreception. In the current study, we fully described the morphological characteristics of the antennal sensilla in parasitoid wasp Microplitis mediator and analyzed the expression patterns of OBPs and CSPs within the antennae. In M. mediator, eight types of sensilla were observed on the antennae. Sensilla basiconica type 2 and s. placodea with wall pores may be involved in olfactory perception, whereas s. basiconica type 1 and type 3 with tip pores may play gustatory functions. Among the 18 OBPs and 3 CSPs in M. mediator, 10 OBPs and 2 CSPs were exclusively or primarily expressed in the antennae. In situ hybridization experiments indicated that the 12 antennae-enriched OBPs and CSPs were mapped to five morphological classes of antennal sensilla, including s. basiconica (type 1-3), s. placodea and s. coeloconica. Within the antennae, most of OBP and CSP genes were expressed only in one type of sensilla indicating their differentiated roles in detection of special type of chemical molecules. Our data will lay a foundation to further study the physiological roles of OBPs and CSPs in antennae of parasitoid wasps.

Functional characterization of a Niemann-Pick type C2 protein in the parasitoid wasp Microplitis mediator.

Niemann-Pick type C2 (NPC2) is a type of small soluble protein involved in lipid metabolism and triglyceride accumulation in vertebrates and arthropods. Recent studies have determined that NPC2 also participates in chemical communication of arthropods. In this work, two novel NPC2 proteins (MmedNPC2a and MmedNPC2b) in Microplitis mediator were identified. Real-time quantitative PCR (qPCR) analysis revealed that MmedNPC2a was expressed higher in the antennae than in other tissues of adult wasps compared with MmedNPC2b. Subsequent immunolocalization results demonstrated that NPC2a was located in the lymph cavities of sensilla placodea. To further explore the binding characterization of recombinant MmedNPC2a to 54 candidate odor molecules, a fluorescence binding assay was performed. It was found MmedNPC2a could not bind with selected fatty acids, such as linoleic acid, palmitic acid, stearic acid and octadecenoic acid. However, seven cotton volatiles, 4-ethylbenzaldehyde, 3,4-dimethylbenzaldehyde, ß-ionone, linalool, m-xylene, benzaldehyde and trans-2-hexen-1-al showed certain binding abilities with MmedNPC2a. Moreover, the predicted 3D model of MmedNPC2a was composed of seven ß-sheets and three pairs of disulfide bridges. In this model, the key binding residues for oleic acid in CjapNPC2 of Camponotus japonicus, Lue68, Lys69, Lys70, Phe97, Thr103 and Phe127, are replaced with Phe85, Ser86, His87, Leu113, Tyr119 and Ile143 in MmedNPC2a, respectively. We proposed that MmedNPC2a in M. mediator may play roles in perception of plant volatiles.