VPTMdb: a viral posttranslational modification database.

In viruses, posttranslational modifications (PTMs) are essential for their life cycle. Recognizing viral PTMs is very important for a better understanding of the mechanism of viral infections and finding potential drug targets. However, few studies have investigated the roles of viral PTMs in virus-human interactions using comprehensive viral PTM datasets. To fill this gap, we developed the first comprehensive viral posttranslational modification database (VPTMdb) for collecting systematic information of PTMs in human viruses and infected host cells. The VPTMdb contains 1240 unique viral PTM sites with 8 modification types from 43 viruses (818 experimentally verified PTM sites manually extracted from 150 publications and 422 PTMs extracted from SwissProt) as well as 13 650 infected cells' PTMs extracted from seven global proteomics experiments in six human viruses. The investigation of viral PTM sequences motifs showed that most viral PTMs have the consensus motifs with human proteins in phosphorylation and five cellular kinase families phosphorylate more than 10 viral species. The analysis of protein disordered regions presented that more than 50% glycosylation sites of double-strand DNA viruses are in the disordered regions, whereas single-strand RNA and retroviruses prefer ordered regions. Domain-domain interaction analysis indicating potential roles of viral PTMs play in infections. The findings should make an important contribution to the field of virus-human interaction. Moreover, we created a novel sequence-based classifier named VPTMpre to help users predict viral protein phosphorylation sites. VPTMdb online web server (http://vptmdb.com:8787/VPTMdb/) was implemented for users to download viral PTM data and predict phosphorylation sites of interest.

Fate and occurrence of indoxacarb during radish cultivation for multi-risk assessment.

Agrochemical indoxacarb is an important tool for selective pest control in radish that be consumed globally. A rapid and sensitive analytical method UHPLC-MS/MS was developed for tracing indoxacarb in radish leaves and roots with LOQ of 0.001 mg/kg and RT within 2 min, which were confirmed the satisfied storage stability of indoxacarb in radish matrixes with degradation rates less than 30 %. The occurrence, pharmacokinetics dissipation and concentration variation of indoxacarb were reflected by the original deposition of 2.23-4.12 mg/kg, half-lives of 2.6-8.0 d and terminal magnitude of 0.17 × 10-2-25.46 mg/kg in radish, and the influencing factors were further illustrated in terms of climate factors, crop cultivars and soil properties. The highest residues of indoxacarb were 25.46 mg/kg in leaves and 0.12 mg/kg in roots, which were higher than international maximum residue limits. A probabilistic model, as well as deterministic model, were introduced to evaluated the health risks of indoxacarb offering a better description for uncertainty. The total chronic dietary risk values of indoxacarb were 146.961-482.065 % in 12 registered crops, of which ADI % in radish was accounted for 19.8 % with risk dilution effects. The unacceptable acute dietary risks of 121.358-220.331 % were observed at 99.9th percentile, whereas the high-potential non-carcinogenic effects were observed over 90th percentile (105.035-1121.943 %). The health risks should be continuously emphasized given the increasing applications and persistent characteristics of indoxacarb, which is vital to protect the human population from hazardous effects, particularly for vulnerable children.

Unique and generic crossed metabolism in response to four sub-lethal environmental stresses in the oriental fruit fly, Bactrocera dorsalis Hendel.

Bactrocera dorsalis is a well-known invasive pest that causes considerable ecological and economic losses worldwild. Although it has a wide environmental tolerance, few studies have reported its mechanism of adaptation to multiple sub-lethal environmental stresses. In this study, 38, 41, 39 and 34 metabolites changed significantly in B. dorsalis under four sub-lethal stresses (heat, cold, desiccation and hypoxia), as found by the metabolomic method. Therein, lactic acid and pyruvic acid were induced, whereas metabolites in the tricarboxylic acid (TCA) cycle such as citric acid, α-ketoglutarate acid, malic acid and fumaric acid were reduced under at least one of the stresses. Enzyme activity and quantitative polymerase chain reaction (qPCR) analyses verified the repression of pyruvic acid proceeding into the TCA cycle. In addition, the levels of several cryoprotectants and membrane fatty acids in B. dorsalis were altered. The findings indicated that B. dorsalis has evolved shared metabolic pathways to adapt to heat, hypoxia and desiccation stresses, such as reducing energy consumption by activating the anaerobic glycolytic metabolism. Cryoprotectants and membrane fatty acids were produced to improve the efficiency of stress resistance. This study revealed the unique and generic crossed physiological mechanism of insects to adapt to various environmental stresses.

miR-31-5p regulates cold acclimation of the wood-boring beetle Monochamus alternatus via ascaroside signaling.

BACKGROUND: Survival to cold stress in insects living in temperate environments requires the deployment of strategies that lead to physiological changes involved in freeze tolerance or freeze avoidance. These strategies may consist of, for instance, the induction of metabolic depression, accumulation of cryoprotectants, or the production of antifreeze proteins, however, little is known about the way such mechanisms are regulated and the signals involved in their activation. Ascarosides are signaling molecules usually known to regulate nematode behavior and development, whose expression was recently found to relate to thermal plasticity in the Japanese pine sawyer beetle Monochamus alternatus. Accumulating evidence also points to miRNAs as another class of regulators differentially expressed in response to cold stress, which are predicted to target genes involved in cold adaptation of insects. Here, we demonstrate a novel pathway involved in insect cold acclimation, through miRNA-mediated regulation of ascaroside function. RESULTS: We initially discovered that experimental cold acclimation can enhance the beetle's cold hardiness. Through screening and functional verification, we found miR-31-5p, upregulated under cold stress, significantly contributes to this enhancement. Mechanistically, miR-31-5p promotes production of an ascaroside (asc-C9) in the beetle by negatively targeting the rate-limiting enzyme, acyl-CoA oxidase in peroxisomal ß-oxidation cycles. Feeding experiments with synthetic asc-C9 suggests it may serve as a signal to promote cold acclimation through metabolic depression and accumulation of cryoprotectants with specific gene expression patterns. CONCLUSIONS: Our results point to important roles of miRNA-mediated regulation of ascaroside function in insect cold adaptation. This enhanced cold tolerance may allow higher survival of M. alternatus in winter and be pivotal in shaping its wide distribution range, greatly expanding the threat of pine wilt disease, and thus can also inspire the development of ascaroside-based pest management strategies.

Gene family expansion of pinewood nematode to detoxify its host defence chemicals.

Gene gain/loss in the context of gene family dynamics plays an important role in evolutionary processes as organisms, particularly invasive species, adapt to new environments or niches. One notable example of this is the duplication of digestive proteases in some parasitic insects and helminths to meet nutritional requirements during animal parasitism. However, whether gene family expansion participates in the adaptation of a plant parasite nematode to its host remains unknown. Here, we compared the newly sequenced genomes of the pinewood nematode, Bursaphelenchus xylophilus, with the genomes of free-living, animal-parasitic and plant-parasitic nematodes. The results showed gene expansions occurring in 51 gene families in B. xylophilus, especially in xenobiotic detoxification pathways, including flavin monooxygenase (FMO), cytochrome P450 (CYP450), short chain dehydrogenase (SDR), alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), UDP-glucuronosyltransferase (UGT) and glutathione S-transferase (GST). Although a majority of these expansions probably resulted from gene duplications, nine ADH genes were potentially acquired by horizontal gene transfer (HGT) from fungi. From the transcriptomes of B. xylophilus treated with pine saplings and terpenes, candidate xenobiotic detoxification genes were identified. We propose that host defence chemicals led to gene family expansions of xenobiotic detoxification pathways in B. xylophilus facilitating its survival in pine resin ducts. This study contributes to a better understanding of how a parasitic nematode adapts to its host.

Metabotropic glutamate receptor 5 regulates synaptic plasticity in a chronic migraine rat model through the PKC/NR2B signal.

BACKGROUND: The mechanism of chronic migraine (CM) is complex, central sensitization is considered as one of the pathological mechanism. Synaptic plasticity is the basis of central sensitization. Metabotropic glutamate receptor 5 (mGluR5) plays a vital role in the synaptic plasticity of the central nervous system. However, whether mGluR5 can promote the central sensitization by regulating synaptic plasticity in CM is unknown. METHODS: Male Wistar rats were used to establish a CM rat model, and the expression of mGluR5 mRNA and protein were detected by qRT-PCR and western blot. The allodynia was assessed by mechanical and thermal thresholds, and central sensitization was assessed by expression of the phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) at Serine 133(pCREB-S133) and c-Fos. The synaptic-associated protein postsynaptic density protein 95 (PSD), synaptophysin (Syp), and synaptophysin-1(Syt-1), synaptic ultrastructure, and dendritic spines were detected to explore synaptic plasticity. The expression of PKC, total NR2B(tNR2B), and phosphorylation of NR2B at Tyr1472(pNR2B-Y1472) were detected by western blot. RESULTS: We found that the expression of mGluR5 was upregulated in CM rats. Downregulated the mGluR5 with MPEP alleviated the allodynia and reduced the expression of CGRP, pCREB-S133, c-Fos, PSD, Syp and Syt-1 and synaptic transmission. Moreover, the administration of MPEP inhibited the upregulation of PKC and pNR2B-Y1472. CONCLUSIONS: These results indicate that mGluR5 contributes to central sensitization by regulating synaptic plasticity in CM through the PKC/NR2B signal, which suggests that mGluR5 may be a potential therapeutic candidate for CM.

Immune tolerance of vector beetle to its partner plant parasitic nematode modulated by its insect parasitic nematode.

Immune response of insect vectors to transmitted pathogens or insect hosts against parasites are well studied, whereas the mechanism of tripartite interactions remains elusive. In this study, we investigated the immune interactions of the vector beetle Monochamus alternatus ( Ma) to the devastating plant parasitic nematode Bursaphelenchus xylophilus ( Bx) and the insect parasitic nematode Howardula phyllotretae ( Hp). We report the unique immune mechanism by which the vector beetle tolerates many devastating Bx in its trachea, yet that immune tolerance is compromised by the parasitic nematode Hp. Contact with either nematode species triggers epithelial reactive oxygen species (ROS) production in Ma. Only the entry of Bx, not Hp, infection, induces increased expression of antioxidative genes, through which the ROS levels are balanced in the trachea of beetles. Furthermore, we found that up-regulation of antioxidative genes was induced by the interaction of Toll receptors. In contrast, beetles infected by Hp retain high levels of oxidative stress and melanization in trachea, and as a result, decrease Bx loading. This study highlights the role of Toll receptors in mediating the activation of antioxidative genes in immune tolerance to plant parasitic nematodes, and suggests the use of insect parasites as a biologic control.-Zhou, J., Zhao, L.-L., Yu, H.-Y., Wang, Y.-H., Zhang, W., Hu, S.-N., Zou, Z., Sun, J.-H. Immune tolerance of vector beetle to its partner plant parasitic nematode modulated by its insect parasitic nematode.

Ascarosides Promote the Prevalence of Ophiostomatoid Fungi and an Invasive Pathogenic Nematode, Bursaphelenchus xylophilus.

Understanding the coevolution of pathogens and their associated mycoflora depend upon a proper elucidation of the basis of their chemical communication. In the case of pine wilt disease, the mutual interactions between cerambycid beetles, invasive pathogenic nematodes, (Bursaphelenchus xylophilus) and their symbiotic ophiostomatoid fungi provide a unique opportunity to understand the role of small molecules in mediating their chemical communication. Nematodes produce ascarosides, a highly conserved family of small molecules that serve essential functions in nematode biology and ecology. Here we demonstrated that the associated fungi, one of the key natural food resources of pine wood nematodes, can detect and respond to these ascarosides. We found that ascarosides significantly increase the growth of L. pini-densiflorae and Sporothrix sp. 1, which are native fungal species in China that form a symbiotic relationship with pinewood nematodes. Hyphal mass of L. pini-densiflorae increased when treated with asc-C5 compared to other ophiostomatoid species. Field results demonstrated that in forests where higher numbers of PWN were isolated from beetle galleries, L. pini-densiflorae had been prevalent; the same results were confirmed in laboratory studies. Furthermore, when treated with asc-C5, L. pini-densiflorae responded by increasing its production of spores, which leads to a higher likelihood of dispersal by insect vectors, hence explaining the dominance of L. pini-densiflorae over S. sp. 1 in the Tianwang and Nanlu Mountains within the Northern Forestry Centre of China. These findings provide an emphatic representation of coevolution of pine wood nematode and its associated fungi. Our results lay a broader foundation for a better understanding of inter-kingdom mutualisms and the chemical signals that mediate their establishment.

Chemical Signals of Vector Beetle Facilitate the Prevalence of a Native Fungus and the Invasive Pinewood Nematode.

In China, the invasive Bursaphelenchus xylophilus, the vector Monochamus alternatus beetle, and associated fungi exhibit a symbiotic relationship causing serious losses to pine forests. Although this complex system has been intensively investigated, the role of vector beetles on the development of associated fungi and their indirect contribution to the prevalence of pinewood nematode (PWN) is yet unknown. Here, three of the highly prevalent fungal species, viz., Sporothrix sp. 1, Ophiostoma ips, and Sporothrix sp. 2 were isolated from beetle chambers in diseased trees in Guangdong province, southeast China. Pairwise cultivation of isolated fungi demonstrated the dominance of Sporothrix sp. 1 over O. ips and Sporothrix sp. 2. On the other hand, two fatty acid ethyl esters (FAEE), ethyl palmitate (EP) and ethyl linoleate (EL), isolated from the body surface of the vector beetle enhanced the growth of Sporothrix sp. 1. When PWN were cultured on Sporothrix sp. 1, the fecundity and the body length were increased significantly as compared with when cultured on O. ips and Sporothrix sp. 1. Our results suggest that the vector beetles promote Sporothrix sp. 1 to occupy more niches by rapid growth and spread, which in turn better support PWN population, hence facilitate PWN pathogenicity in the invasive regions.

Mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor.

In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were HgCl2, HgS and HgO. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor, existed in two forms, HgBr2 and HgO, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of HgBr2 and HgO in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time.

Fate characteristics and risk quantification of cyflumetofen from tomato cultivation to processing based on large-scale applications.

Elucidating the fate characteristics of cyflumetofen and its main metabolite 2-TFMBA in tomato from cultivation to processing is crucial for safeguarding the environment and humans from hazardous effects. Cyflumetofen and 2-TFMBA could exist stably in tomato matrices for at least 343 days under frozen and dark conditions according to UHPLC-MS/MS, with a limit of quantitation of 0.001 mg/kg and retention time within 2.12 min. The occurrence, dissipation, and concentration variation of cyflumetofen were reflected by original depositions of 0.02-0.44 mg/kg, half-lives of 1.7-7.2 days, and terminal magnitudes of 0.005-0.30 mg/kg, respectively, with various influencing factors, e.g., climate conditions and tomato cultivars. Additionally, 13.5-59.3% of cyflumetofen was metabolized to 2-TFMBA, showing significant toxicological effects ranging from cultivation to processing. When the concentration decreased by 0.06 mg/kg, cyflumetofen was effectively removed by peeling, while washing was the recommended method for removing 2-TFMBA with a processing factor of 0.70. The comparative dietary risks of sum cyflumetofen were assessed for all life cycle populations using deterministic and probabilistic models. The risk quotients decreased to 1.3-4.8 times during the preparation of home canning tomato paste. Despite the low exposure risk, the potential health hazards of sum cyflumetofen should be considered, given its ubiquity and cumulative effects.

A native fungal symbiont facilitates the prevalence and development of an invasive pathogen-native vector symbiosis.

Invasive pathogen-insect symbioses have been extensively studied in many different ecological niches. Whether the damage of symbioses in different introduced regions might be influenced by other microorganisms has, however, received little attention. Eight years of field data showed that the varied levels of the nematode and beetle populations and infested trees of the invasive Bursaphelenchus xylophilus--Monochamus alternatus symbiosis were correlated with patterns in the isolation frequencies of ophiostomatoid fungi at six sites, while the laboratory experiments showed that the nematode produced greater numbers of offspring with a female-biased sex ratio and developed faster in the presence of one native symbiotic ophiostomatoid fungus, Sporothrix sp. 1. Diacetone alcohol (DAA) from xylem inoculated with Sporothrix sp. 1 induced B. xylophilus to produce greater numbers of offspring. Its presence also significantly increased the growth and survival rate of M. alternatus, and possibly explains the prevalence of the nematode-vector symbiosis when Sporothrix sp. 1 was dominant in the fungal communities. Studying the means by which multispecies interactions contributed to biogeographical dynamics allowed us to better understand the varied levels of damage caused by biological invasion across the invaded range.

[Effect of GLP-1 on high glucose-induced human umbilical vein endothelial cell apoptosis and mechanism].

OBJECTIVE: To investigate the effects of glucagon-like peptide-1 (GLP-1) on high glucose-induced apoptosis of human umbilical vein endothelial cells (HUVECs) and the mechanism involved. METHODS: HUVECs were cultured under varying conditions for 48 h, and the cell viability was spectrophotometrically measured by MTT assay. Flow cytometry detected the ratio of cell apoptosis. Western blot detected the protein levels of p-Akt and p-eNOS, while NO assay kit detected the NO concentration. RESULTS: Treatment of high glucose (33 mmol/L) for 48 h significantly decreased the HUVECs viability and induced the apoptosis of HUVECs, concomitant with decreased Akt and eNOS phosphorylation leves and subsequent NO production. Treatment with GLP-1 (3 nmol/L) for 48 h in the high glucose group increased the HUVECs viability (P<0.01), decreased the ratio of HUVECs early apoptosis (P<0.05), ameliorated the reduced protein levels of p-Akt and p-eNOS caused by high glucose, and increased the NO production (P<0.05). The anti-apoptotic effect and the increased NO production of GLP-1were inhibited by PI3K inhibitor wortmannine (100 nmol/L) or eNOS inhibitor L-NAME (100 µmol/L). The effect on p-Akt, p-eNOS of GLP-1 was inhibited by wortmannine (100 nmol/L) while L-NAME (100 µmol/L) did not have any influence on the expression of p-Akt. CONCLUSION: GLP-1 can ameliorate high glucose-induced HUVECs apoptosis, which is probably related to the up-regulation of PI3K/Akt/eNOS pathway.

Large-scale fate profiling of butralin between cultivated and processed garlics for multi-risk estimations.

Elaborating on the fate profiling and risk magnitude of butralin during large-scale applications was conducive to agroecosystems sustainability and dietary rationality. Occurrence, dissipation and concentration variation of butralin were elucidated from garlic cultivation to household processing by tracing UHPLC-MS/MS within 2 min, with regard to original depositions, half-lives, and terminal magnitude in typical origins of garlic. The processing factors (Pfs) of butralin were further clarified among washing, stir-frying and pickling of garlic crops, and pickling was the most effective way for butralin removal with a Pf of 0.092. A probabilistic model with Pfs was further introduced for the comprehensive risk estimations, by reduction factors of 3.1-10.9 from raw garlic crops to processed products. The short-term risks of butralin from green garlic were greater than those between garlic shoot and garlic, with the %ARfDs of 0.030 %-6.323 % from 50th to 99.9th percentiles. The long-term risks were inversely correlated to the age of the population, whose location in rural (%ADIs, 0.256 %-0.768 %) suffered more serious exposures than in urban (%ADIs, 0.231 %-0.699 %). High potential risk amplification should be continuously emphasized given the increasing applications and persistent fate of butralin, especially for vulnerable rural children.

Palmitoleic acid as a coordinating molecule between the invasive pinewood nematode and its newly associated fungi.

Symbiotic microorganisms are ubiquitous on the body surface or internal tissues of invertebrates, providing them with benefits. Developing symbiotic relationships requires synchronization of developmental stages and physical proximity of partners. Therefore, the identification of metabolites that coordinate the reproduction of symbiotic partners is essential. This study demonstrates that palmitoleic acid (C16: 1) coordinates bilateral propagation by regulating the synchronization of reproduction between the invasive pinewood nematode (PWN) and its newly associated blue-stain fungus, Sporothrix sp.1. When the PWN fed on Sporothrix sp.1, there was a significant increase in lipid metabolism gene expression and metabolite abundance. Through further investigations, it highlighted a significant enhancement in the reproduction of the PWN through direct acquisition of C16: 1, which was abundantly present in Sporothrix sp.1. Furthermore, the PWN biosynthesized C16: 1 through the involvement of the stearoyl-CoA 9-desaturase gene fat-5 and its hormone nuclear receptor nhr-80, which was clarified to promote the egg-laying capacity of females. Moreover, it is worth noting that the production of C16: 1 was significantly higher by the associated fungus Sporothrix sp.1 to enhance sporulation during the spore formation phase compared to the hypha growth phase. Thus, by coordinating the fecundity and spore production, the key lipid metabolite C16: 1 facilitates the rapid and successful colonization of a mutually beneficial symbiotic relationship between the invasive PWN and the native Sporothrix sp.1 within the host. This finding emphasizes the significant role of metabolite sharing and its function in promoting partner synchronization within symbiotic relationships.

Temperature-regulated metabolites of Serratiamarcescens inhibited reproduction of pinewood nematode Bursaphelenchus xylophilus.

The pinewood nematode Bursaphelenchus xylophilus is an invasive and destructive pathogen in forestry. Serratia marcescens AHPC29 was previously found to have nematicidal activity on B. xylophilus. The effect of AHPC29 growth temperature on B. xylophilus inhibition is unknown. Here we show that AHPC29 cultured at 15°C or 25°C, but not 37°C, inhibited B. xylophilus reproduction. Metabolomic analysis found 31 up-regulated metabolites as potential effective substances in this temperature-related difference, with five of them were tested to be effective in inhibiting B. xylophilus reproduction. Among the five metabolites, salsolinol was further verified in bacterial cultures with effective inhibition concentrations. This study found the inhibition of S. marcescens AHPC29 on B. xylophilus reproduction was temperature regulated and the differently expressed metabolites salsolinol played roles in this temperature-regulated effect, which implies the capability of S. marcescens and its metabolites as promising new agents for the management of B. xylophilus.

Health risks of dietary ethirimol exposure demand attention in China: A study of nationwide applications.

The health risks for dietary exposure after large-scale ethirimol application demand attention to protect the human population from hazardous effects. The occurrence, dissipation and terminal magnitude of ethirimol were revealed by original deposition of <0.005-28.1 mg kg-1, half-lives of 0.6-14.5 d, and terminal concentrations of  spinach > leaf lettuce > pepper > cucumber > papaya > pumpkin > stem lettuce > muskmelon > wax gourd > mango. The high-potential health risks of ethirimol should be continuously emphasized for susceptible children aged 2-13 years, especially those residing in rural areas and presenting increasing vegetable intake.

Risk assessment framework for pine wilt disease: Estimating the introduction pathways and multispecies interactions among the pine wood nematode, its insect vectors, and hosts in China.

Pine wilt disease (PWD), caused by the pine wood nematode (PWN, Bursaphelenchus xylophilus), a destructive, invasive forest pathogen, poses a serious threat to global pine forest ecosystems. The global invasion of PWN has been described based on three successive phases, introduction, establishment, and dispersal. Risk assessments of the three successive PWN invasion phases can assist in targeted management efforts. Here, we present a risk assessment framework to evaluate the introduction, establishment, and dispersal risks of PWD in China using network analysis, species distribution models, and niche concepts. We found that >88 % of PWN inspection records were from the United States, South Korea, Japan, Germany, and Mexico, and 94 % of interception records were primarily from the Jiangsu, Shanghai, Shandong, Tianjin, and Zhejiang ports. Based on the nearly current climate, the areas of PWN overlap with its host Pinus species were primarily distributed in southern, eastern, Yangtze River Basin, central, and northeastern China regions. Areas of PWN overlap with its insect vector Monochamus alternatus were primarily distributed in southern, eastern, Yangtze River Basin, central, and northeastern China regions, and those of PWN overlap with the insect vector Monochamus saltuarius were primarily distributed in eastern and northeastern China. The niche between PWN and the insect vector M. alternatus was the most similar (0.68), followed by that between PWN and the insect vector M. saltuarius (0.47). Climate change will increase the suitable probabilities of PWN and its two insect vectors occurring at high latitudes, further increasing their threat to hosts in northeastern China. This risk assessment framework for PWD could be influential in preventing the entry of the PWN and mitigating their establishment and dispersal risks in China. Our study provides substantial clues for developing a framework to improve the risk assessment and surveillance of biological invasions worldwide.

Hypoxia-induced tracheal elasticity in vector beetle facilitates the loading of pinewood nematode.

Many pathogens rely on their insect vectors for transmission. Such pathogens are under selection to improve vector competence for their transmission by employing various tissue or cellular responses of vectors. However, whether pathogens can actively cause hypoxia in vectors and exploit hypoxia responses to promote their vector competence is still unknown. Fast dispersal of pinewood nematode (PWN), the causal agent for the destructive pine wilt disease and subsequent infection of pine trees, is characterized by the high vector competence of pine sawyer beetles (Monochamus spp.), and a single beetle can harbor over 200,000 PWNs in its tracheal system. Here, we demonstrate that PWN loading activates hypoxia in tracheal system of the vector beetles. Both PWN loading and hypoxia enhanced tracheal elasticity and thickened the apical extracellular matrix (aECM) of the tracheal tubes while a notable upregulated expression of a resilin-like mucin protein Muc91C was observed at the aECM layer of PWN-loaded and hypoxic tracheal tubes. RNAi knockdown of Muc91C reduced tracheal elasticity and aECM thickness under hypoxia conditions and thus decreasing PWN loading. Our study suggests a crucial role of hypoxia-induced developmental responses in shaping vector tolerance to the pathogen and provides clues for potential molecular targets to control pathogen dissemination.

Various parasites, bacteria and other disease-causing pathogens are transmitted by insects. A tiny worm called the pine wood nematode, for example, is spread by pine sawyer beetles which can carry up to 280,000 worms in their trachea, the network of tubes they use to breathe. This has resulted in millions of hectares of pine forests in Asia and Europe becoming infected with the deadly disease caused by the nematodes. Pine wood nematodes, as well as other pathogens, can exploit the biological processes of the insects carrying them to make the insects transmit them more effectively. Precisely how nematodes and other disease-causing agents do this is unclear. One possibility is that they reduce the amount of oxygen being supplied to the trachea ­ a phenomenon known as hypoxia ­ which occurs naturally at specific stages in the life of an insect, and during infections. To test this theory, Tang, Zhou, Koski et al. used genetics and imaging approaches to study how pine wood nematodes affect the trachea of pine sawyer beetles. The experiments found that when the nematodes infected the beetles, their trachea did indeed develop hypoxia. This, in turn, made the beetles' airways more elastic and made the layer of structure lining the trachea, known as the apical extracellular matrix, thicker. These changes increased the amount of pinewood nematodes the trachea could hold, allowing the beetle to spread more worms from tree to tree. Further experiments revealed that hypoxia in the trachea increased the levels of a protein called Muc91C in the apical extracellular matrix. When the levels of Muc91C were artificially decreased in the beetles, this made their airways less elastic and the apical extracellular matrix thinner. This work suggests that pine wood nematodes exploit the beetles' normal responses to loss of oxygen supply to make the beetles more effective at transmitting the nematodes between pine trees. Other pathogens carried by insects may also use this strategy to help increase their transmission. Further studies on the Muc91C protein may provide clues for potential drug targets to control pine wood nematodes and protect pine trees from disease.

Neural circuit mechanisms linking courtship and reward in Drosophila males.

Courtship has evolved to achieve reproductive success in animal species. However, whether courtship itself has a positive value remains unclear. In the present work, we report that courtship is innately rewarding and can induce the expression of appetitive short-term memory (STM) and long-term memory (LTM) in Drosophila melanogaster males. Activation of male-specific P1 neurons is sufficient to mimic courtship-induced preference and memory performance. Surprisingly, P1 neurons functionally connect to a large proportion of dopaminergic neurons (DANs) in the protocerebral anterior medial (PAM) cluster. The acquisition of STM and LTM depends on two distinct subsets of PAM DANs that convey the courtship-reward signal to the restricted regions of the mushroom body (MB) γ and α/ß lobes through two dopamine receptors, D1-like Dop1R1 and D2-like Dop2R. Furthermore, the retrieval of STM stored in the MB α'/ß' lobes and LTM stored in the MB α/ß lobe relies on two distinct MB output neurons. Finally, LTM consolidation requires two subsets of PAM DANs projecting to the MB α/ß lobe and corresponding MB output neurons. Taken together, our findings demonstrate that courtship is a potent rewarding stimulus and reveal the underlying neural circuit mechanisms linking courtship and reward in Drosophila males.