Cellular senescence-Related genes define the immune microenvironment and molecular characteristics in severe asthma patients.

Recent studies have shown that cellular senescence is involved in the pathogenesis of severe asthma (SA). The objective of this study was to investigate the role of cellular senescence-related genes (CSGs) in the pathogenesis of SA. Here, 54 differentially expressed CSGs were identified in SA patients compared to healthy control individuals. Among the 54 differentially expressed CSGs, 3 CSGs (ETS2, ETS1 and AURKA) were screened using the LASSO regression analysis and logistic regression analysis to establish the CSG-based prediction model to predict severe asthma. Moreover, we found that the protein expression levels of ETS2, ETS1 and AURKA were increased in the severe asthma mouse model. Then, two distinct senescence subtypes of SA with distinct immune microenvironments and molecular biological characteristics were identified. Cluster 1 was characterized by increased infiltration of immature dendritic cells, regulatory T cells, and other cells. Cluster 2 was characterized by increased infiltration levels of eosinophils, neutrophils, and other cells. The molecular biological characteristics of Cluster 1 included aerobic respiration and oxidative phosphorylation, whereas the molecular biological characteristics of Cluster 2 included activation of the immune response and immune receptor activity. Then, we established an Random Forest model to predict the senescence subtypes of SA to guide treatment. Finally, potential drugs were searched for each senescence subgroup of SA patients via the Connectivity Map database. A peroxisome proliferator-activated receptor agonist may be a potential therapeutic drug for patients in Cluster 1, whereas a tachykinin antagonist may be a potential therapeutic drug for patients in Cluster 2. In summary, CSGs are likely involved in the pathogenesis of SA, which may lead to new therapeutic options for SA patients.

Role of sulfatide-reactive vNKT cells in promoting lung Treg cells via dendritic cell modulation in asthma models.

Our previous studies have showed that sulfatide-reactive type II NKT (i.e. variant NKT, vNKT) cells inhibit the immunogenic maturation during the development of mature lung dendritic cells (LDCs), leading todeclined allergic airway inflammation in asthma. Nonetheless, the specific immunoregulatory roles of vNKT cells in LDC-mediated Th2 cell responses remain incompletely understood. Herein, we found that administration of sulfatide facilitated the generation of CD4+FoxP3+ regulatory T (Treg) cells in the lungs of wild-type mice, but not in CD1d-/- and Jα18-/- mice, after ovalbumin or house dust mite exposure. This finding implies that the enhancement of lung Treg cells by sulfatide requires vNKT cells, which dependent on invariant NKT (iNKT) cells. Furthermore, the CD4+FoxP3+ Treg cells induced by sulfatide-reactive vNKT cells were found to be associated with PD-L1 molecules expressed on LDCs, and this association was dependent on iNKT cells. Collectively, our findings suggest that in asthma-mimicking murine models, sulfatide-reactive vNKT cells facilitate the generation of lung Treg cells through inducing tolerogenic properties in LDCs, and this process is dependent on the presence of lung iNKT cells. These results may provide a potential therapeutic approach to treat allergic asthma.

Anti-CD20 treatment attenuates Th2 cell responses: implications for the role of lung follicular mature B cells in the asthmatic mice.

BACKGROUND: B cells were believed to act as antigen-presenting cells (APCs) to promote T helper type 2 (Th2) cell responses. However, the role of lung B cells and its subpopulations in Th2 cell responses in asthma remains unclear. OBJECTIVE: We leveraged an anti-CD20 monoclonal antibody (mAb) treatment that has been shown to selectively deplete B cells in mice and investigated whether this treatment modulates Th2 cell responses and this modulation is related to lung follicular mature (FM) B cells in a murine model of asthma. METHODS AND RESULTS: We used a house dust mite (HDM)-induced asthma mouse model and found that anti-CD20 mAb treatment attenuates Th2 cell responses. Meanwhile, anti-CD20 mAb treatment did dramatically reduce the number of B cells, especially FM B cells in the lungs, but did not impact the frequency of other immune cell types, including lung T cells, dendritic cells, natural killer cells, and regulatory T cells in wild-type mice. Moreover, we found that the suppressive effect of anti-CD20 mAb treatment on Th2 cell responses could be reversed upon adoptive transfer of lung FM B cells, but not lung CD19+ B cells without FM B cells in asthmatic mice. CONCLUSIONS: These findings reveal that anti-CD20 mAb treatment alleviates Th2 cell responses, possibly by depleting lung FM B cells in a Th2-driven asthma model. This implies a potential therapeutic approach for asthma treatment through the targeting of lung FM B cells.

Anti-CD1d treatment suppresses immunogenic maturation of lung dendritic cells dependent on lung invariant natural killer T cells in asthmatic mice.

Our previous findings show that invariant natural killer T (iNKT)cells can promote immunogenic maturation of lung dendritic cells (LDCs) to enhance Th2 cell responses in asthma. It has been accepted that recognition of glycolipid antigens presented by CD1d molecules by the T cell receptors of iNKT cells leads to iNKT cell activation. Therefore, we examine the immunoregulatory influences of anti-CD1d treatment on Th2 cell response and immunogenic maturation of LDCs and subsequently explored whether these influences were dependent on lung iNKT cells in asthmatic mice. We discoveredthat in wild-type mice sensitized and challenged with house dust mite or ovalbumin (OVA), anti-CD1d treatment inhibited Th2 cell response and immunogenic maturation of LDCs. LDCs from asthmatic mice with anti-CD1d treatment had a markedly decreased influence on Th2 cell responses in vivo and in vitro. Furthermore, anti-CD1d treatment reduced the abundance and activation of lung iNKT cells in asthmatic mice. Moreover, in asthmatic iNKT cell-deficient Jα18-/- mice, anti-CD1d treatment did not influence Th2 cell responses and immunogenic maturation of LDCs. Meanwhile, the quantity of CD40L+ iNKT cells in asthmatic mice was significant decreased by anti-CD1d treatment. Finally, the inhibition of anti-CD1d treatment on LDC immunogenic maturation and Th2 cell responses in asthmatic mice was reversed by anti-CD40 treatment. Our data suggest that anti-CD1d treatment can suppress Th2 cell responses through inhibiting immunogenic maturation of LDCs dependent on lung iNKT cells, which couldbe partially related to the downregulation of CD40L expression on lung iNKT cells in asthmatic mice.

A case report of healthcare-associated psittacosis.

INTRODUCTION: Psittacosis is a well-recognized zoonotic infectious disorder caused by Chlamydia psittaci (C. psittaci). Human-to-human transmission of C. psittaci has rarely been reported previously, especially in the case of healthcare-associated infections. CASE REPORT: A 32-year-old man was admitted to the intensive care unit with severe pneumonia. An intensive care unit healthcare worker contracted pneumonia 7 days after performing endotracheal intubation on the patient. The first patient, a duck feeder, had been closely exposed to ducks, while the second patient had not been exposed to any birds, mammals or poultry. C. psittaci sequences were obtained by metagenomic next-generation sequencing analyses of bronchial alveolar lavage fluid of both the patients, and they were diagnosed with psittacosis. Therefore, healthcare-associated human-to-human transmission between both cases took place. CONCLUSIONS: Our findings have implications for managing patients with suspected psittacosis. stringent protective measures are needed to prevent healthcare-associated human-to-human transmission of C. psittaci.

Analysis of risk factors of fungal superinfections in viral pneumonia patients: A systematic review and meta-analysis.

BACKGROUND: Infections with fungi, such as Aspergillus species, have been found as common complications of viral pneumonia. This study aims to determine the risk factors of fungal superinfections in viral pneumonia patients using meta-analysis. OBJECTIVE: This study aims to determine the risk factors of fungal infection s in viral pneumonia patients using meta-analysis. METHODS: We reviewed primary literature about fungal infection in viral pneumonia patients published between January 1, 2010 and September 30, 2020, in the Chinese Biomedical Literature, Chinese National Knowledge Infrastructure, Wanfang (China), Cochrane Central Library, Embase, PubMed, and Web of Science databases. These studies were subjected to an array of statistical analyses, including risk of bias and sensitivity analyses. RESULTS: In this study, we found a statistically significant difference in the incidence of fungal infections in viral pneumonia patients that received corticosteroid treatment as compared to those without corticosteroid treatment (p < .00001). Additionally, regarding the severity of fungal infections, we observed significant higher incidence of invasive pulmonary aspergillosis (IPA) in patients with high Acute Physiology and Chronic Health Evaluation (APACHE) II scores (p < .001), tumors (p = .005), or immunocompromised patients (p < .0001). CONCLUSIONS: Our research shows that corticosteroid treatment was an important risk factor for the development of fungal infection in patients with viral pneumonia. High APACHE II scores, tumors, and immunocompromised condition are also important risk factors of developing IPA. The diagnosis of fungal infection in viral pneumonia patients can be facilitated by early serum galactomannan (GM) testing, bronchoalveolar lavage fluid Aspergillus antigen testing, culture, and biopsy.

Identification of hub genes and potential biomarkers of neutrophilic asthma: evidence from a bioinformatics analysis.

OBJECTIVE: Asthma is a chronic airway inflammatory disease caused by multiple genetic and environmental factors. This study mainly sought to provide potential therapeutic targets and biomarkers for neutrophilic asthma (NA). METHODS: Three gene expression profiling datasets were obtained from the Genome Expression Omnibus (GEO) database. GSE45111 and GSE41863 were used to identify hub genes and potential biomarkers, and GSE137268 was used for data verification. We verified the repeatability of intragroup data and identified differentially expressed genes (DEGs). Then, we conducted Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the DEGs, and a protein-protein interaction (PPI) network was constructed to identify the hub genes. Finally, receiver operating characteristic (ROC) analysis was used to verify the ability of the hub genes to differentiate between NA and eosinophilic asthma (EA). RESULTS: In this study, we identified 411 DEGs by comprehensive analysis of NA/EA patients and NA/healthy controls (HCs). Ten hub genes (CXCR1, FCGR3B, CXCR2, SELL, S100A12, CSF3R, IL6R, JAK3, CD48, and GNG2) were identified from the PPI network. Finally, based on the ROC analysis, 7 genes showed good diagnostic value for discriminating NA from EA-CXCR1, FCGR3B, CXCR2, SELL, S100A12, CSF3R, and IL6R (AUC > 0.7). CONCLUSION: We identified 7 hub genes that can distinguish NA from EA. The IL-8-mediated signaling may be the primary pathway to determine the NA phenotype in asthma. CXCR1/2 and S100A12 may be the primary genes determining the NA phenotype. CXCR1/2 and S100A12 might be biomarkers and new therapeutic targets for NA.Supplemental data for this article is available online at at.

Low-dose 5-fluorouracil ameliorates Th2 responses through the induction of apoptotic cell death of lung monocyte-derived dendritic cells in asthma.

5-Fluorouracil (5-FU) is an analog of pyrimidine and has been shown to display antitumor and immunomodulatory effects. However, the impacts of 5-FU in regulating asthma, an inflammatory disease associated with T helper cell 2 (Th2) responses, remain unclear. Here, we determine the modulatory effects of low-dose 5-FU on Th2 cell responses in asthma and delineate the underlying mechanisms using adoptive cell transfer and in vitro culture experiments. Our data show that low-dose 5-FU treatment not only inhibits the induction of asthma in allergen-sensitized mice but also abrogates the major features of asthma in mice with established disease. We find that this protection of 5-FU treatment against asthma is accompanied by a decrease in the number of lung monocyte-derived dendritic cells (moDCs) in the asthmatic murine. Furthermore, we show that adoptive transfer of moDCs reverses the inhibitory effects of 5-FU treatment on Th2 cell responses in asthmatic mice. Surprisingly, 5-FU treatment does not suppress surface maturation markers and immunogenicity of moDCs in the lungs of asthmatic mice. Instead, it induces apoptotic cell death of mouse moDCs both in vitro and in vivo. In addition to its impact on mouse moDCs, we observe that low-dose 5-FU treatment can induce apoptotic cell death of human moDCs derived from peripheral blood mononuclear cells in vitro. Together, our findings reveal that low-dose 5-FU ameliorates Th2 cell responses, which may be at least partially related to the induction of apoptotic cell death of moDCs in asthma.

Cross-talk of four types of RNA modification writers defines the immune microenvironment in severe asthma.

Adenine modifications, including m6 A, m1 A, APA, and A-to-I modifications, are the most impactful RNA modifications. These modifications are primarily produced by enzymes called writers. The main purpose of this study was to explore the cross-talk and potential roles of these writers in severe asthma. We found 13 RNA writers potentially related to severe asthma and three RNA modification patterns. Cluster 3 showed predominant neutrophil infiltration and C-type lectin receptor signaling; cluster 1 showed predominant innate immune cell infiltration and ubiquitin-proteasome system activation; and cluster 2 did not show obvious immune infiltration characteristics. We found that RNA modification writers modified immune cell-related genes and led to both accumulation of different immune cells in the airways and activation of a series of biological processes, which ultimately leads to severe asthma. TRMT6, WTAP, and TRMT6A were included in a random forest model as predictors. Cromoglicic acid, thioperamide, and fluvastatin were potential drugs for clusters 1, 2, and 3, respectively. We found that cross-talk of RNA modifications is significant in severe asthma, which provides insight into severe asthma pathogenesis and possible treatment avenues.

Efficacy and safety of percutaneous tube drainage in lung abscess: a systematic review and meta-analysis.

Objectives: Lung abscess is an infectious lung disease. The main objective of this review was to assess the efficacy and safety of percutaneous tube drainage (PTD) in patients with lung abscess by systematic review and meta-analysis of published data. Methods: We searched all literature published between 1 January 2010, and 6 August 2019, in the PubMed, Cochrane Central Library, EMBASE, Wanfang, Chinese National Knowledge Infrastructure, and Chinese Biomedical Literature databases for relevant reports. The data from these studies were pooled for statistical analysis, and sensitivity analysis and risk-of-bias analysis was performed. Results: Meta-analysis revealed that percutaneous tube drainage (PTD) was superior to conservative treatment in terms of the total effectivity rate (P < 0.01). Moreover, length of hospital stay and number of fever days were reduced for the PTD group than for the group receiving conservative treatment (P < 0.01). There was no significant difference between PTD and conservative treatment in terms of complication rate (P = 0.43). Conclusion: Lung abscess drainage is a safe and effective method for treating lung abscesses. Based on the principle that as much drainage as possible should be performed as treatment of abscess diseases, drainage should be promoted as treatment for lung abscess.

A novel glycoside hydrolase family 42 enzyme with bifunctional ß-galactosidase and α-L-arabinopyranosidase activities and its synergistic effects with cognate glycoside hydrolases in plant polysaccharides degradation.

GH42 enzymes are potential candidates for bifunctional ß-galactosidase/α-L-arabinopyranosidase. A novel GH42 enzyme (BaBgal42A) from Bacillus was identified, the recombinant BaBgal42A hydrolyzed not only ß-D-galactopyranosidic bonds in pNP-ß-D-galactopyranoside, oNP-ß-D-galactopyranoside, lactose, galactan, and arabinan but also α-L-arabinopyranosidic linkages in pNP-α-L-arabinopyranoside, wheat arabinoxylan and galactan. The Km values of BaBgal42A for pNP-ß-D-galactopyranoside and pNP-α-L-arabinopyranoside were 2.76 and 16.23 mM, respectively. Investigation of cooperative activities of BaBgal42A with cognate enzymes revealed that BaBgal42A showed obvious synergy with an endo-ß-1,4-galactanase (BaGal53A) in the decomposition of galactan, supplementing BaBgal42A resulted in a 0.56-fold increase in the release of reducing sugars; BaBgal42A also exhibited a little synergy with its cognate endoxylanase (BaXynA)/α-L-arabinofuranosidase (BaAraA) in hydrolyzing wheat arabinoxylan/arabinan, addition of BaBgal42A released 12.7%/7.8% more reducing sugars than that produced by BaXynA/BaAraA alone. Moreover, BaBgal42A is a cold-adapted enzyme, exhibiting 28-46% of the maximal activity at the range of 5-20 °C and its activity was slightly stimulated by addition of Na+, K+, or Ca2+ at low concentrations. This study not only expands the diversity within GH42 family, but also provides new insights into the role of microbial GH42 enzymes, which would contribute to its potential application in polysaccharides degradation and milk lactose hydrolysis.

Effects of breathing exercises using home-based positive pressure in the expiratory phase in patients with COPD.

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) commonly have higher intrinsic positive end-expiratory pressure (PEEPi). A breathing exercise programme strategy employing an appropriate PEEP may improve their pulmonary functional capacity, exercise tolerance and health-related quality of life. Breathing with an expiratory resistive load, which is a method of modulating spontaneous breathing against PEEPi, has not been fully studied in patients with COPD. The objective of this study was to investigate the role of changing spontaneous breathing in home-based conditions and regulating spontaneous breathing with breathing exercises in patients with COPD. METHODS: This was a prospective randomised trial including 64 patients with a diagnosis of stage III or IV COPD. Patients were randomised into two groups: standard treatment and standard treatment combined with breathing exercise rehabilitation. The effects of the treatments on the COPD assessment test (CAT) score, 6-minute walk test (6MWT) results and pulmonary function were compared at 0, 6, 12 and 18 months within and between the two groups. RESULTS: All outcomes showed no significant differences between the two groups at the beginning of the study, while the 6MWT and CAT scores exhibited clinically and statistically significant improvements (p<0.001) by the end of the study. At month 18, the change in the predicted percentage of forced expiratory volume in 1 s (FEV1%pred) differed between the two groups (p<0.05). In addition, there were statistically significant differences in the 6MWT results, CAT scores and FEV1%pred values between the baseline and month 18 (p<0.0001) in the intervention group. CONCLUSIONS: Improvements in 6MWT results, pulmonary function and CAT scores are associated with a successful response to breathing against PEEPi in patients with COPD. TRIAL REGISTRATION: This trial was registered at research registry.com (identifier research registry 4816).

A novel thermostable GH10 xylanase with activities on a wide variety of cellulosic substrates from a xylanolytic Bacillus strain exhibiting significant synergy with commercial Celluclast 1.5 L in pretreated corn stover hydrolysis.

BACKGROUND: Cellulose and hemicellulose are the two largest components in lignocellulosic biomass. Enzymes with activities towards cellulose and xylan have attracted great interest in the bioconversion of lignocellulosic biomass, since they have potential in improving the hydrolytic performance and reducing the enzyme costs. Exploring glycoside hydrolases (GHs) with good thermostability and activities on xylan and cellulose would be beneficial to the industrial production of biofuels and bio-based chemicals. RESULTS: A novel GH10 enzyme (XynA) identified from a xylanolytic strain Bacillus sp. KW1 was cloned and expressed. Its optimal pH and temperature were determined to be pH 6.0 and 65 °C. Stability analyses revealed that XynA was stable over a broad pH range (pH 6.0-11.0) after being incubated at 25 °C for 24 h. Moreover, XynA retained over 95% activity after heat treatment at 60 °C for 60 h, and its half-lives at 65 °C and 70 °C were about 12 h and 1.5 h, respectively. More importantly, in terms of substrate specificity, XynA exhibits hydrolytic activities towards xylans, microcrystalline cellulose (filter paper and Avicel), carboxymethyl cellulose (CMC), cellobiose, p-nitrophenyl-ß-d-cellobioside (pNPC), and p-nitrophenyl-ß-d-glucopyranoside (pNPG). Furthermore, the addition of XynA into commercial cellulase in the hydrolysis of pretreated corn stover resulted in remarkable increases (the relative increases may up to 90%) in the release of reducing sugars. Finally, it is worth mentioning that XynA only shows high amino acid sequence identity (88%) with rXynAHJ14, a GH10 xylanase with no activity on CMC. The similarities with other characterized GH10 enzymes, including xylanases and bifunctional xylanase/cellulase enzymes, are no more than 30%. CONCLUSIONS: XynA is a novel thermostable GH10 xylanase with a wide substrate spectrum. It displays good stability in a broad range of pH and high temperatures, and exhibits activities towards xylans and a wide variety of cellulosic substrates, which are not found in other GH10 enzymes. The enzyme also has high capacity in saccharification of pretreated corn stover. These characteristics make XynA a good candidate not only for assisting cellulase in lignocellulosic biomass hydrolysis, but also for the research on structure-function relationship of bifunctional xylanase/cellulase.

Geospallins A⁻C: New Thiodiketopiperazines with Inhibitory Activity against Angiotensin-Converting Enzyme from a Deep-Sea-Derived Fungus Geosmithia pallida FS140.

Three new thiodiketopiperazines, geospallins A⁻C (1⁻3), together with nine known analogues (4⁻12), were isolated from the culture of the deep-sea sediment-derived fungus Geosmithia pallida FS140. Among them, geospallins A and B (1 and 2) represent rare examples of thiodiketopiperazines featuring an S-methyl group at C-10 and a tertiary hydroxyl group at C-11. Their structures were determined by high-resolution electrospray mass spectrometry (HRESIMS), spectroscopic analyses, and electronic circular dichroism (ECD) calculations. Their angiotensin-converting enzyme (ACE) inhibitory activity was reported, and geospallins A⁻C (1⁻3) showed inhibitory activity with IC50 values of 29⁻35 µM.

The LBD12-1 Transcription Factor Suppresses Apical Meristem Size by Repressing Argonaute 10 Expression.

The shoot apical meristem (SAM) consists of a population of multipotent cells that generates all aerial structures and regenerates itself. SAM maintenance and lateral organ development are regulated by several complex signaling pathways, in which the Argonaute gene-mediated pathway plays a key role. One Argonaute gene, AGO10, functions as a microRNA locker that attenuates miR165/166 activity and positively regulates shoot apical meristem development, but little is known about when and how AGO10 is regulated at the transcriptional level. In this work, we showed that transgenic rice plants overexpressing LBD12-1, an LBD family transcription factor, exhibited stunted growth, twisted leaves, abnormal anthers, and reduced SAM size. Further research revealed that LBD12-1 directly binds to the promoter region and represses the expression of AGO10. Overexpression of AGO10 in an LBD12-1 overexpression background rescued the growth defect phenotype of LBD12-1-overexpressing plants. The expression of LBD12-1 and its binding ability to the AGO10 promoter is induced by stress. lbd12-1 loss-of-function mutants showed similar phenotypes and SAM size to the wild type under normal conditions, but lbd12-1 had a larger SAM under salt stress. Our findings provide novel insights into the regulatory mechanism of AGO10 by which SAM size is controlled under stress conditions.

Microstructure, optical properties, and catalytic performance of Cu2O-modified ZnO nanorods prepared by electrodeposition.

Cu2O-modified ZnO nanorods are prepared by a two-step electrodeposition method on ITO substrates, and the deposition time of Cu2O is 0, 1, 5, and 10 min, respectively. Cu2O particles are embedded in the interspaces of the ZnO nanorods, and the amounts of the Cu2O particles increase obviously when the deposition time lasts longer. The peaks corresponding to ZnO nanorods and Cu2O particles are detected from scanning electron microscope (SEM) and X-ray diffraction (XRD) results. UV-vis absorption spectra measurements have shown the bandgaps of ZnO nanorods shift from 3.22 to 2.75 eV. The methyl orange (MO) concentration can be reduced to around 15% in 100 min with Cu2O electrodeposition time for 10 min.

Tip of the clade on the top of the World--the first fossil Lophopidae (Hemiptera: Fulgoromorpha) from the Palaeocene of Tibet.

Lophopidae is a family of planthoppers (Hemiptera: Fulgoromorpha) present today in tropical and subtropical zones of the Old World. The most recent taxonomic studies and phylogeny of these insects do not include the extinct representatives. Therefore, each new discovery of a fossil lophopid is of high interest, giving new insights to their evolutionary history and enabling to test the proposed relationships. The recent findings of extinct Lophopidae in Europe, in various Palaeogene deposits, put in doubts their proposed evolutionary and biogeographic scenario. The new fossil from the Palaeocene of Northern Tibet is related to one of the Lophopidae clades, Apia(+) group, believed to be the most advanced one, and recently distributed in the recent Sundaland-New Guinea-Queensland area. A new genus and species Gesaris gnapo gen. et sp. n. provide information on early lophopids diversity and relationships and demonstrates the necessity for a revision of the existing hypotheses for the initial diversification and distributional pattern of the Lophopidae.

Amphibious flies and paedomorphism in the Jurassic period.

The species of the Strashilidae (strashilids) have been the most perplexing of fossil insects from the Jurassic period of Russia and China. They have been widely considered to be ectoparasites of pterosaurs or feathered dinosaurs, based on the putative presence of piercing and sucking mouthparts and hind tibio-basitarsal pincers purportedly used to fix onto the host's hairs or feathers. Both the supposed host and parasite occur in the Daohugou beds from the Middle Jurassic epoch of China (approximately 165 million years ago). Here we analyse the morphology of strashilids from the Daohugou beds, and reach markedly different conclusions; namely that strashilids are highly specialized flies (Diptera) bearing large membranous wings, with substantial sexual dimorphism of the hind legs and abdominal extensions. The idea that they belong to an extinct order is unsupported, and the lineage can be placed within the true flies. In terms of major morphological and inferred behavioural features, strashilids resemble the recent (extant) and relict members of the aquatic fly family Nymphomyiidae. Their ontogeny are distinguished by the persistence in adult males of larval abdominal respiratory gills, representing a unique case of paedomorphism among endopterygote insects. Adult strashilids were probably aquatic or amphibious, shedding their wings after emergence and mating in the water.