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Chemical communication plays a vital role in mate attraction and discrimination among many insect species. Here, we document a unique example of semiochemical parsimony, where four chemicals act as both aphrodisiacs and anti-aphrodisiacs in different contexts in Bactrocera dorsalis. Specifically, we identified four female-specific semiochemicals, ethyl laurate, ethyl myristate, ethyl cis-9-hexadecenoate, and ethyl palmitate, which serve as aphrodisiacs to attract male flies and arouse male courtship. Interestingly, these semiochemicals, when sexually transferred to males during mating, can function as anti-aphrodisiacs, inhibiting the receptivity of subsequent female mates. We further showed that the expression of elongase11, a key enzyme involved in the biosynthesis of these semiochemicals, is under the control of doublesex, facilitating the exclusive biosynthesis of these four semiochemicals in females and guaranteeing effective chemical communication. The dual roles of these semiochemicals not only ensure the attractiveness of mature females but also provide a simple yet reliable mechanism for female mate discrimination. These findings provide insights into chemical communication in B. dorsalis and add elements for the design of pest control programs.
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Afrodisíacos , Tephritidae , Animais , Feminino , Masculino , Feromônios/metabolismo , Corte , Ácidos Graxos Monoinsaturados/farmacologia , Comportamento Sexual AnimalRESUMO
A kagome lattice hosts a plethora of quantum states arising from the interplay between nontrivial topology and electron correlations. The recently discovered kagome magnet RMn6Sn6 (R represents a rare-earth element) is believed to showcase a kagome band closely resembling textbook characteristics. Here, we report the characterization of local electronic states and their magnetization response in YMn6Sn6 via scanning tunneling microscopy measurements under vector magnetic fields. Our spectroscopic maps reveal a spontaneously trimerized kagome electronic order in YMn6Sn6, where the 6-fold rotational symmetry is disrupted while translational symmetry is maintained. Further application of an external magnetic field demonstrates a strong coupling of the YMn6Sn6 kagome band to the field, which exhibits an energy shift discrepancy under different field directions, implying the existence of magnetization-response anisotropy and anomalous g factors. Our findings establish YMn6Sn6 as an ideal platform for investigating kagome-derived orbital magnetic moment and correlated magnetic topological states.
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Acute graft-versus-host disease (aGVHD) is primarily driven by allogeneic donor T cells associated with an altered composition of the host gut microbiome and its metabolites. The severity of aGVHD after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is not solely determined by the host and donor characteristics; however, the underlying mechanisms remain unclear. Using single-cell RNA sequencing, we decoded the immune cell atlas of 12 patients who underwent allo-HSCT: six with aGVHD and six with non-aGVHD. We performed a fecal microbiota (16SrRNA sequencing) analysis to investigate the fecal bacterial composition of 82 patients: 30 with aGVHD and 52 with non-aGVHD. Fecal samples from these patients were analyzed for bile acid metabolism. Through multi-omic analysis, we identified a feedback loop involving "immune cell-gut microbes-bile acid metabolites" contributing to heightened immune responses in patients with aGVHD. The dysbiosis of the gut microbiota and disruption of bile acid metabolism contributed to an exaggerated interleukin-1 mediated immune response. Our findings suggest that resistin and defensins are crucial in mitigating against aGVHD. Therefore, a comprehensive multi-omic atlas incorporating immune cells, gut microbes, and bile acid metabolites was developed in this study and used to propose novel, non-immunosuppressive approaches to prevent aGVHD.
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Ácidos e Sais Biliares , Fezes , Microbioma Gastrointestinal , Doença Enxerto-Hospedeiro , Ácidos e Sais Biliares/metabolismo , Humanos , Doença Enxerto-Hospedeiro/imunologia , Doença Enxerto-Hospedeiro/microbiologia , Microbioma Gastrointestinal/imunologia , Feminino , Masculino , Fezes/microbiologia , Pessoa de Meia-Idade , Doença Aguda , Adulto , Retroalimentação Fisiológica , Imunidade , Metabolômica , Transplante de Células-Tronco Hematopoéticas , MultiômicaRESUMO
Brain injury caused by stroke has a high rate of mortality and remains a major medical challenge worldwide. In recent years, there has been significant attention given to the use of human Umbilical cord-derived Mesenchymal Stem Cells (hUC-MSCs) for the treatment of stroke in different adult and neonate animal models of stroke. However, using hUC-MSCs by systemic administration to treat ischemic stroke has not been investigated sufficiently. In this study, we conducted various experiments to explore the neuroprotection of hUC-MSCs in rats. Our findings demonstrate that an intravenous injection of a high dose of hUC-MSCs at 2 × 10^7 cells/kg markedly ameliorated brain injury resulting from ischemic stroke. This improvement was observed one day after inducing transient middle cerebral artery occlusion (MCAO) and subsequent reperfusion in rats. Notably, the efficacy of this single administration of hUC-MSCs surpassed that of edaravone, even when the latter was used continuously over three days. Mechanistically, secretory factors derived from hUC-MSCs, such as HGF, BDNF, and TNFR1, ameliorated the levels of MDA and T-SOD to regulate oxidative stress. In particular, TNFR1 also improved the expression of NQO-1 and HO-1, important proteins associated with oxidative stress. More importantly, TNFR1 played a significant role in reducing inflammation by modulating IL-6 levels in the blood. Furthermore, TNFR1 was observed to influence the permeability of the blood-brain barrier (BBB) as demonstrated in the evan's blue experiment and protein expression of ZO-1. This study represented a breakthrough in traditional methods and provided a novel strategy for clinical medication and trials.
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AVC Isquêmico , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Estresse Oxidativo , Ratos Sprague-Dawley , Cordão Umbilical , Animais , Estresse Oxidativo/fisiologia , Humanos , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/metabolismo , Cordão Umbilical/citologia , Masculino , AVC Isquêmico/metabolismo , AVC Isquêmico/terapia , Ratos , Inflamação/metabolismo , Lesões Encefálicas/metabolismo , Lesões Encefálicas/terapia , Neuroproteção/fisiologia , Infarto da Artéria Cerebral Média/terapia , Infarto da Artéria Cerebral Média/metabolismoRESUMO
Antibiotic resistance is a global threat. Antimicrobial peptides (AMPs) are highly desirable to treat multidrug-resistant pathogen infection. However, few AMPs are clinically available, due to high cost, instability, and poor selectivity. Here, ultrashort AMPs (2-3 residues with an N-terminal cysteine) are designed and assembled as gold nanoparticles. Au-S conjugation and ultrashort size restrict nonspecific reactions and peptide orientation, thus concentrating positively charged residues on the surface. The nanostructured assemblies enormously enhance antimicrobial abilities by 1000-6000-fold and stability. One representative (Au-Cys-Arg-NH2, Au_CR) shows selective antibacterial activity against Staphylococcus aureus with 10 nM minimal inhibitory concentration. Au_CR has comparable or better in vivo antimicrobial potency than vancomycin and methicillin, with low propensity to induce resistance, little side effects, and high stability (17.5 h plasma half-life). Au_CR acts by inducing collapse of membrane potential and rupture of the bacterial membrane. The report provides insights for developing AMP-metal nanohybrids, particularly tethering nonspecific reactions and AMP orientation on the metal surface.
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Anti-Infecciosos , Nanopartículas Metálicas , Ouro/química , Dipeptídeos , Peptídeos Catiônicos Antimicrobianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/química , Nanopartículas Metálicas/química , Anti-Infecciosos/química , Antibacterianos/farmacologia , Antibacterianos/química , Testes de Sensibilidade MicrobianaRESUMO
Birefringent crystal, which has the capacity to manipulate polarization light, holds an indispensable position in optics and optoelectronics, while it remains challenging to fulfill the modulation of birefringence. Here, we present wide spectral photo-pyroelectric effect in a silver-based hybrid pyroelectric, (N-CHM)Ag2I3 (N-CHM = N-cyclohexylmethylamine), serving as a feasible strategy to regulate birefringence through light stimuli. As the first silver-based hybrid pyroelectric, (N-CHM)Ag2I3 exhibits strong room-temperature photo-pyroelectricity with a large polarization of ~3.23 µC/cm2 and high voltage responsivity of ~0.96 m2/C across the UV-NIR spectral region. Strikingly, the photomodulation of its in-plane birefringence is established through pyroelectric effect, giving a saturation value of ~1.68×10-2 that is among the highest level achieved to date. This study on the birefringence photomodulation of lead-free hybrid pyroelectric is anticipated to boost future development of new smart optical and optoelectronic devices.
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Two-dimensional (2D) hybrid perovskite materials have been widely used for polarization-sensitive photodetection due to their fascinating optical and physical attributes. However, studies on those materials that enable strong polarized-light activities under a weak-light condition remain quite scarce. Here, by tailoring aromatic cation into 3D prototype, we have successfully obtained a new 2D hybrid perovskite, (FPEA)2 (MA)Pb2 Br7 (1, where FPEA is 4-fluorophenethylammonium and MA is methylammonium). The alternative alignment of inorganic and organic structural components results in significant anisotropy, including optical absorption and electric conductivity. The coupling effect of these anisotropic properties in 1 gives rise to strong dichroic activities toward detecting polarized light. Especially, under weak light intensity (â¼330â nW/cm2 ), it can still generate a large polarization ratio up to 1.35, which is even higher than those of some typical 2D materials (i. e., GeSe â¼1.09). Besides, single crystal-based photodetector of 1 displays fascinating detecting performances, including large photocurrent on/off ratio (â¼104 ), fast response time (â¼154/182â µs) and excellent antifatigued stability. These findings disclose the potentials of 1 as a robust candidate for detecting weak polarized light, which has practical applications in the field of polarized optoelectronics.
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Compostos de Cálcio , Luz , Anisotropia , Condutividade ElétricaRESUMO
An asymmetric [3+2] cycloaddition of quinone esters with 2,3-dihydrofuran has been realized via a newly developed Cu(II)/SPDO complex. It provides straightforward access to 2,3,3a,8a-tetrahydrofuro[2,3-b]benzofurans (TFB) with high enantioselectivity (up to 97.5:2.5 er) and diastereoselectivity (all >20:1 dr). The resulting adducts contain two adjacent stereocenters and a continuously functionalized benzene ring. Additionally, this transformation could be easily performed on a gram scale, allowing for expedient synthesis of natural dihydroaflatoxin D2 and aflatoxin B2.
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Ecosystem vulnerability is an ecological response of the environment to external damage. Studying the influencing factors and spatiotemporal changes of ecosystem vulnerability is helpful to maintain ecological balance. At present, studies on ecosystem vulnerability are relatively homogeneous and rarely integrate climate change and human activities. Based on a habitat-function framework, this study analyzed the response of ecosystem vulnerability on climate change and human activities in the Poyang Lake City Group (PLCG) in 2010, 2015 and 2020. The spatial agglomeration of ecosystem vulnerability has been analyzed by using GeoDa model. The interaction of factors on ecosystem vulnerability have been analyzed by using geographical detector. It can be seen that the ecosystem vulnerability of the PLCG have increased from 2010 to 2020. The impacts of climate change to the ecosystem vulnerability have showed a positive correlation. Meanwhile, the key factors leading to the change of ecological vulnerability are still human activities. This methodology demonstrates a high level of robustness when applied to other research domains. This research is conducive to maintaining the integrity of the ecosystem, realizing the development of man and nature, and promoting the sound and rapid development of economic society.
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Ecossistema , Lagos , Humanos , Mudança Climática , China , Atividades HumanasRESUMO
Microplastics (MPs) can enrich pollutants after being released into the environment, and the contaminants-loaded MPs are usually ingested by organisms, resulting in a potential dual biotoxic effect. In this paper, the adsorption behavior of Sulfamethoxazole (SMX) on Polyamide 6 (PA6) MPs was systematically investigated and simulated by the kinetic and isotherm models. The effect of environmental conditions (pH, salinity) on the adsorption process was studied, and the desorption behavior of SMX-loaded PA6 MPs was focused on simulating the seawater, ultrapure water, gastric and intestinal fluids. We found that lower pH and solubilization of SMX by gastrointestinal components (bovine serum albumin (BSA), sodium taurocholate (NaT), and pepsin) can reduce the electrostatic interaction between the surface charge of PA6 MPs and SMX. The result will lead to an increase in the desorption capacity of SMX-loaded PA6 MPs in gastrointestinal fluids and therefore will provide a reasonable mechanism for the desorption of SMX-loaded PA6 MPs in the gastrointestinal fluids. This study will provide a theoretical reference for studying the desorption behavior of SMX-loaded PA6 MPs under gastrointestinal conditions.
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Microplásticos , Plásticos , Estômago , SulfametoxazolRESUMO
The female reproductive potential plays a crucial role in reproduction, population dynamics and population maintenance. However, the function of endogenous genes in undifferentiated germ cells has been largely unknown in Bactrocera dorsalis. In this study, the conservative analysis showed that α-Spectrin shared a similarity in B. dorsalis and other dipteral flies. Further, the differential expression of α-Spectrin was examined in B. dorsalis by RT-qPCR, and the expression pattern of α-Spectrin protein was identified in female adult ovaries by using immunostaining. During the development of ovary, the change on the number of undifferentiated germ cells was also characterized and analyzed. To understand the function of α-Spectrin in B. dorsalis ovary, the RNAi-based knockdown was conducted, and the RNAi efficiency was examined by RT-qPCR, western blot and bioassay. The results revealed that the α-Spectrin dsRNA could strikingly decrease the expression level of α-Spectrin in ovaries and diminish oviposition and ovary size as a consequence of downregulation of α-Spectrin. Overall, our study facilitates reproductive research on the function of conservative genes in B. dorsalis ovary, which may provide a new insight into seeking novel target genes for pest management control.
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Espectrina , Tephritidae , Animais , Feminino , Interferência de RNA , Espectrina/genética , Espectrina/metabolismo , Reprodução , Tephritidae/genéticaRESUMO
BACKGROUND: Oral squamous cell carcinoma (OSCC) is a disease with increasing incidence worldwide that leads to deformity and death. In OSCC, fascin actin-bundling protein 1 (FSCN1) is an oncogene involved in the tumorigenesis process. However, the functions and potential mechanisms of FSCN1 in the OSCC tumorigenesis process have not been reported thus far. METHODS: We used qRTâPCR to detect the expression of FSCN1 in 40 paired OSCC tumor tissues (tumor) and neighboring noncancerous tissues. The role of FSCN1 was also assessed in vitro through colony formation, CCK-8, and transwell assays. Moreover, glucose consumption was detected. Western blotting was used to confirm the interaction of FSCN1, IRF4 and AKT. RESULTS: FSCN1 was remarkably overexpressed in OSCC tissues and cell lines compared to corresponding controls. In addition, colony formation, CCK-8, and transwell assays revealed a notable reduction in OSCC growth and invasion when FSCN1 was silenced. FSCN1 silencing remarkably suppressed OSCC glycolysis. Mechanistic studies showed that FSCN1 achieves its function partially by activating interferon regulatory factor 4 (IRF4) and the AKT pathway in OSCC. CONCLUSION: In conclusion, our study investigated the functions and mechanisms of the FSCN1/IRF4/AKT pathway in OSCC progression. In OSCC, FSCN1 is likely to be a biomarker and therapeutic target.
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Neoplasias Bucais , Carcinoma de Células Escamosas de Cabeça e Pescoço , Humanos , Carcinogênese , Proteínas de Transporte/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Glicólise , Fatores Reguladores de Interferon/genética , Fatores Reguladores de Interferon/metabolismo , Neoplasias Bucais/patologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologiaRESUMO
To limit the spread of severe acute respiratory syndrome coronavirus 2, the government of China has been monitoring infected travelers and minimizing cold-chain contamination. However, other factors might contribute to recurring outbreaks. We analyze the role of undocumented migrants as potential transmitters of severe acute respiratory syndrome coronavirus 2 in China.
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COVID-19 , Migrantes , China/epidemiologia , Surtos de Doenças , Humanos , SARS-CoV-2RESUMO
Charge density wave (CDW) is an intriguing physical phenomenon especially found in two-dimensional (2D) layered systems such as transition-metal dichalcogenides (TMDs). The study of CDW is vital for understanding lattice modification, strongly correlated electronic behaviors, and other related physical properties. This paper gives a review of the recent studies on CDW emerging in 2D TMDs. First, a brief introduction and the main mechanisms of CDW are given. Second, the interplay between CDW patterns and the related unique electronic phenomena (superconductivity, spin, and Mottness) is elucidated. Then various manipulation methods such as doping, applying strain, local voltage pulse to induce the CDW change are discussed. Finally, examples of the potential application of devices based on CDW materials are given. We also discuss the current challenge and opportunities at the frontier in this research field.
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BACKGROUND: Botulinum neurotoxin A (BoNT-A) was the primary choice for preventive treatment of chronic migraine. Topiramate and acupuncture showed promising effect for chronic migraine, but their effectiveness relative to BoNT-A was rarely studied. We aimed to perform a network meta-analysis to compare the effectiveness and acceptability between topiramate, acupuncture, and BoNT-A. METHODS: We searched OVID Medline, Embase, the Cochrane register of controlled trials (CENTRAL), the Chinese Clinical Trial Register, and clinicaltrials.gov for randomized controlled trials (RCTs) that compared topiramate, acupuncture, and BoNT-A with any of them or placebo in the preventive treatment of chronic migraine. A network meta-analysis was performed by using a frequentist approach and a random-effects model. The primary outcomes were reduction in monthly headache days and monthly migraine days at week 12. Acceptability was defined as the number of dropouts owing to adverse events. RESULTS: We included 15 RCTs (n = 2545). Eleven RCTs were at low risk of bias. The network meta-analyses (n = 2061) showed that acupuncture (2061 participants; standardized mean difference [SMD] -1.61, 95% CI: -2.35 to -0.87) and topiramate (582 participants; SMD -0.4, 95% CI: -0.75 to -0.04) ranked the most effective in the reduction of monthly headache days and migraine days, respectively; but they were not significantly superior over BoNT-A. Topiramate caused the most treatment-related adverse events and the highest rate of dropouts owing to adverse events. CONCLUSIONS: Topiramate and acupuncture were not superior over BoNT-A; BoNT-A was still the primary preventive treatment of chronic migraine. Large-scale RCTs with direct comparison of these three treatments are warranted to verified the findings.
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Terapia por Acupuntura/métodos , Toxinas Botulínicas Tipo A/uso terapêutico , Transtornos de Enxaqueca/prevenção & controle , Topiramato/uso terapêutico , Adulto , Feminino , Humanos , Metanálise em RedeRESUMO
X-ray repair cross-complementing group 1 (Xrcc1), a key DNA repair gene, plays a vital role in maintaining genomic stability and is highly expressed in the early stages of spermatogenesis, but the exact functions remain elusive. Here we generated primordial germ cell-specific Xrcc1 knockout (cXrcc1-/-) mice to elucidate the effects of Xrcc1 on spermatogenesis. We demonstrated that Xrcc1 deficiency results in infertility in male mice due to impaired spermatogenesis. We found that cXrcc1-/- mice exhibited smaller size of testes as well as lower sperm concentration and motility than the wild-type mice. Mechanistically, we demonstrated that Xrcc1 deficiency in primordial germ cells induced elevated levels of reactive oxygen species, mitochondria dysfunction, apoptosis, and loss of stemness of spermatogonial stem cells (SSCs) in testes. In Xrcc1-deficienct SSCs, elevated oxidative stress and mitochondrial dysfunction could be partially reversed by treatment with the antioxidant N-acetylcysteine (NAC), whereas NAC treatment did not restore the fertility or ameliorate the apoptosis caused by loss of Xrcc1. Overall, our findings provided new insights into understanding the crucial role of Xrcc1 during spermatogenesis.-Xu, C., Xu, J., Ji, G., Liu, Q., Shao, W., Chen, Y., Gu, J., Weng, Z., Zhang, X., Wang, Y., Gu, A. Deficiency of X-ray repair cross-complementing group 1 in primordial germ cells contributes to male infertility.
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Células Germinativas/metabolismo , Infertilidade Masculina/genética , Proteína 1 Complementadora Cruzada de Reparo de Raio-X/genética , Acetilcisteína/farmacologia , Animais , Apoptose , Feminino , Células Germinativas/efeitos dos fármacos , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Testículo/citologia , Testículo/metabolismoRESUMO
BACKGROUND: The emergence of human infection with avian influenza A(H7N9) virus was reported in Wenshan City, southwestern China in 2017. The study describes the epidemiological and virological features of the outbreak and discusses the origin of the infection. METHODS: Poultry exposure and timelines of key events for each patient were collected. Samples derived from the patients, their close contacts, and environments were tested for influenza A(H7N9) virus by real-time reverse transcription polymerase chain reaction. Genetic sequencing and phylogenetic analysis were also conducted. RESULTS: Five patients were reported in the outbreak. An epidemiological investigation showed that all patients had been exposed at live poultry markets. The A(H7N9) isolates from these patients had low pathogenicity in avian species. Both epidemiological investigations of chicken sources and phylogenetic analysis of viral gene sequences indicated that the source of infection was from Guangxi Province, which lies 100 km to the east of Wenshan City. CONCLUSIONS: In the study, a sudden emergence of human cases of H7N9 was documented in urban area of Wenshan City. Chickens were an important carrier in the H7N9 virus spreading from Guangxi to Wenshan. Hygienic management of live poultry markets and virological screening of chickens transported across regions should be reinforced to limit the spread of H7N9 virus.
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Subtipo H7N9 do Vírus da Influenza A/genética , Influenza Aviária/virologia , Influenza Humana/epidemiologia , Filogenia , Adulto , Substituição de Aminoácidos , Animais , Pré-Escolar , China/epidemiologia , Surtos de Doenças , Feminino , Humanos , Subtipo H7N9 do Vírus da Influenza A/isolamento & purificação , Subtipo H7N9 do Vírus da Influenza A/patogenicidade , Influenza Humana/tratamento farmacológico , Influenza Humana/virologia , Masculino , Aves Domésticas/virologia , Reação em Cadeia da Polimerase em Tempo RealRESUMO
BACKGROUND: Massive techniques have been evaluated for developing different pest control methods to minimize fertilizer and pesticide inputs. As "push-pull" strategy utilizes generally non-toxic chemicals to manipulate behaviors of insects, such strategy is considered to be environmentally friendly. "Push-pull" strategy has been extraordinarily effective in controlling stem borers, and the identification of new "pushing" or "pull" components against stem borers could be significantly helpful. RESULTS: In this study, the results of field trapping assay and behavioral assay showed the larvae of C.auricilius, one kind of stem borers, could be deterred by rice plant under tilling stage, its main host crop. The profiles of volatiles were compared between rice plants under two different developmental stages, and α-pinene was identified as a key differential component. The repelling activity of α-pinene against C.auricilius was confirmed by Y-tube olfactometer. For illuminating the olfactory recognition mechanism, transcriptome analysis was carried out, and 13 chemosensory proteins (CSPs) were identified in larvae and 19 CSPs were identified in adult of C.auriciliu, which was reported for the first time in this insect. Among these identified CSPs, 4 CSPs were significantly regulated by α-pinene treatment, and CSP8 showed good binding affinity with α-pinene in vitro. CONCLUSIONS: Overall, C.auricilius could be repelled by rice plant at tilling stage, and our results highlighted α-pinene as a key component in inducing repelling activity at this specific stage and confirmed the roles of some candidate chemosensory elements in this chemo-sensing process. The results in this study could provide valuable information for chemosensory mechanism of C.auricilius and for identification of "push" agent against rice stem borers.
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Repelentes de Insetos/metabolismo , Mariposas/fisiologia , Controle Biológico de Vetores/métodos , Doenças das Plantas/prevenção & controle , Compostos Orgânicos Voláteis/metabolismo , Animais , Monoterpenos Bicíclicos/metabolismo , Quimiotaxia/genética , Quimiotaxia/fisiologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Larva/genética , Larva/fisiologia , Mariposas/classificação , Mariposas/genética , Oryza/química , Oryza/genética , Oryza/crescimento & desenvolvimento , Oryza/parasitologia , Doenças das Plantas/parasitologia , Proteínas de Plantas/genética , Ligação ProteicaRESUMO
A new extracellular xylanase was purified from a non-toxic mesophilic fungus Aspergillus flavus, and characterized as the ß-1, 4-endoxylanase (designated as AfXynA) that appeared in a single protein band on SDS-PAGE with a molecular mass of 20.2â¯kDa, which is different from all other reported xylanases from the same strain. The AfXynA exhibited a specific activity of 838.2 U/mg. Its optimal temperature and pH were determined to be 55⯰C and 7.5, respectively. It was stable up to 50⯰C and within pH 3.5-10.5. AfXynA also exhibited an excellent tolerance to various proteases. This new xylanase had an endohydrolytic mode of action and could hydrolyze xylotriose to xylobiose through transglycosylation. It could efficiently degrade xylan to mainly yield xylobiose, xylotriose, xylopentose and xylohexaose. In addition, the AfXynA was effective in hydrolyzing pretreated corncobs, and shows a great potential in the production of xylooligosaccharides. These unique enzymatic properties make the AfXynA attractive for more biotechnological applications.
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Aspergillus flavus/enzimologia , Endo-1,4-beta-Xilanases , Proteínas Fúngicas , Zea mays/química , Endo-1,4-beta-Xilanases/química , Endo-1,4-beta-Xilanases/isolamento & purificação , Estabilidade Enzimática , Proteínas Fúngicas/química , Proteínas Fúngicas/isolamento & purificação , HidróliseRESUMO
BACKGROUND: Two outbreaks of epidemic keratoconjunctivitis (EKC) occurred successively with an interval of 5 days in two primary boarding schools in Weixi Lisu Autonomous County, Diqing, and Tibetan Autonomous Prefecture, Yunnan. The aims of this study were to determine the intensity and characteristics of the outbreaks, as well as the clinical manifestations in the patients, the risk factors for infection and the pathogen responsible for the two outbreaks. METHODS: An outbreak investigation was conducted in two primary schools, and a case-control study including patients from the Weixi County Ethnic Primary School was performed. Relevant specimens were collected according to the case definition, and next-generation sequencing was employed to identify the pathogen. An epidemiological investigation method was used to analyse the related epidemiological characteristics, such as risk factors. The phylogenetic tree was constructed by MEGA 7.0. RESULTS: A total of 331 acute conjunctivitis cases, including probable cases of EKC, were reported in the two schools, and the attack rates were 30.59% (171/559, 95%CI: 26.76-34.42) and 20.41% (160/784, 95%CI: 17.58-23.24), respectively. Cases occurred in all grades and classes in both schools, and only one staff member in each school presented illness. The epidemics lasted for 54 days and 45 days, respectively. The patients had typical manifestations of EKC, such as acute onset, follicular hyperplasia, pseudomembrane formation, preauricular lymphadenopathy, corneal involvement and blurred vision, and a relatively long disease course (average 9.40 days, longest 23 days and shortest 7 days). The risk factor for infection was close contact with a patient or personal items contaminated by a patient. The pathogen responsible for the outbreaks was HAdV-8. The virus was highly similar to the 2016 HAdV-8 strain from Tibet, China. CONCLUSIONS: This study strongly suggests that HAdV-8 could lead to serious consequences. This is the second report of a HAdV-8-associated EKC outbreak in mainland China. Tibetan HAdV-8 might be circulating in southwest China; therefore, it is necessary to monitor the pathogens causing acute conjunctivitis in this area.