28 research outputs found

    Emotional Fuzzy Sliding-Mode Control for Unknown Nonlinear Systems

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    [[abstract]]The brain emotional learning model can be implemented with a simple hardware and processor; however, the learning model cannot model the qualitative aspects of human knowledge. To solve this problem, a fuzzy-based emotional learning model (FELM) with structure and parameter learning is proposed. The membership functions and fuzzy rules can be learned through the derived learning scheme. Further, an emotional fuzzy sliding-mode control (EFSMC) system, which does not need the plant model, is proposed for unknown nonlinear systems. The EFSMC system is applied to an inverted pendulum and a chaotic synchronization. The simulation results with the use of EFSMC system demonstrate the feasibility of FELM learning procedure. The main contributions of this paper are (1) the FELM varies its structure dynamically with a simple computation; (2) the parameter learning imitates the role of emotions in mammalians brain; (3) by combining the advantage of nonsingular terminal sliding-mode control, the EFSMC system provides very high precision and finite-time control performance; (4) the system analysis is given in the sense of the gradient descent method.[[notice]]補正完

    HlSRB, a Class B Scavenger Receptor, Is Key to the Granulocyte-Mediated Microbial Phagocytosis in Ticks

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    Ixodid ticks transmit various pathogens of deadly diseases to humans and animals. However, the specific molecule that functions in the recognition and control of pathogens inside ticks is not yet to be identified. Class B scavenger receptor CD36 (SRB) participates in internalization of apoptotic cells, certain bacterial and fungal pathogens, and modified low-density lipoproteins. Recently, we have reported on recombinant HlSRB, a 50-kDa protein with one hydrophobic SRB domain from the hard tick, Haemaphysalis longicornis. Here, we show that HlSRB plays vital roles in granulocyte-mediated phagocytosis to invading Escherichia coli and contributes to the first-line host defense against various pathogens. Data clearly revealed that granulocytes that up-regulated the expression of cell surface HlSRB are almost exclusively involved in hemocyte-mediated phagocytosis for E. coli in ticks, and post-transcriptional silencing of the HlSRB-specific gene ablated the granulocytes' ability to phagocytose E. coli and resulted in the mortality of ticks due to high bacteremia. This is the first report demonstrating that a scavenger receptor molecule contributes to hemocyte-mediated phagocytosis against exogenous pathogens, isolated and characterized from hematophagous arthropods

    Impact of the Location of CpG Methylation within the GSTP1 Gene on Its Specificity as a DNA Marker for Hepatocellular Carcinoma

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    Hypermethylation of the glutathione S-transferase π 1 (GSTP1) gene promoter region has been reported to be a potential biomarker to distinguish hepatocellular carcinoma (HCC) from other liver diseases. However, reports regarding how specific a marker it is have ranged from 100% to 0%. We hypothesized that, to a large extent, the variation of specificity depends on the location of the CpG sites analyzed. To test this hypothesis, we compared the methylation status of the GSTP1 promoter region of the DNA isolated from HCC, cirrhosis, hepatitis, and normal liver tissues by bisulfite–PCR sequencing. We found that the 5′ region of the position −48 nt from the transcription start site of the GSTP1 gene is selectively methylated in HCC, whereas the 3′ region is methylated in all liver tissues examined, including normal liver and the HCC tissue. Interestingly, when DNA derived from fetal liver and 11 nonhepatic normal tissue was also examined by bisulfite-PCR sequencing, we found that methylation of the 3′ region of the promoter appeared to be liver-specific. A methylation-specific PCR assay targeting the 5′ region of the promoter was developed and used to quantify the methylated GSTP1 gene in various diseased liver tissues including HCC. When we used an assay targeting the 3′ region, we found that the methylation of the 5′-end of the GSTP1 promoter was significantly more specific than that of the 3′-end (97.1% vs. 60%, p<0.0001 by Fisher's exact test) for distinguishing HCC (n = 120) from hepatitis (n = 35) and cirrhosis (n = 35). Encouragingly, 33.8% of the AFP-negative HCC contained the methylated GSTP1 gene. This study clearly demonstrates the importance of the location of CpG site methylation for HCC specificity and how liver-specific DNA methylation should be considered when an epigenetic DNA marker is studied for detection of HCC

    A Cysteine Protease Is Critical for Babesia spp. Transmission in Haemaphysalis Ticks

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    Vector ticks possess a unique system that enables them to digest large amounts of host blood and to transmit various animal and human pathogens, suggesting the existence of evolutionally acquired proteolytic mechanisms. We report here the molecular and reverse genetic characterization of a multifunctional cysteine protease, longipain, from the babesial parasite vector tick Haemaphysalis longicornis. Longipain shares structural similarity with papain-family cysteine proteases obtained from invertebrates and vertebrates. Endogenous longipain was mainly expressed in the midgut epithelium and was specifically localized at lysosomal vacuoles and possibly released into the lumen. Its expression was up-regulated by host blood feeding. Enzymatic functional assays using in vitro and in vivo substrates revealed that longipain hydrolysis occurs over a broad range of pH and temperature. Haemoparasiticidal assays showed that longipain dose-dependently killed tick-borne Babesia parasites, and its babesiacidal effect occurred via specific adherence to the parasite membranes. Disruption of endogenous longipain by RNA interference revealed that longipain is involved in the digestion of the host blood meal. In addition, the knockdown ticks contained an increased number of parasites, suggesting that longipain exerts a killing effect against the midgut-stage Babesia parasites in ticks. Our results suggest that longipain is essential for tick survival, and may have a role in controlling the transmission of tick-transmittable Babesia parasites

    Functional genomics of the horn fly, Haematobia irritans (Linnaeus, 1758)

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    <p>Abstract</p> <p>Background</p> <p>The horn fly, <it>Haematobia irritans </it>(Linnaeus, 1758) (Diptera: Muscidae) is one of the most important ectoparasites of pastured cattle. Horn flies infestations reduce cattle weight gain and milk production. Additionally, horn flies are mechanical vectors of different pathogens that cause disease in cattle. The aim of this study was to conduct a functional genomics study in female horn flies using Expressed Sequence Tags (EST) analysis and RNA interference (RNAi).</p> <p>Results</p> <p>A cDNA library was made from whole abdominal tissues collected from partially fed adult female horn flies. High quality horn fly ESTs (2,160) were sequenced and assembled into 992 unigenes (178 contigs and 814 singlets) representing molecular functions such as serine proteases, cell metabolism, mitochondrial function, transcription and translation, transport, chromatin structure, vitellogenesis, cytoskeleton, DNA replication, cell response to stress and infection, cell proliferation and cell-cell interactions, intracellular trafficking and secretion, and development. Functional analyses were conducted using RNAi for the first time in horn flies. Gene knockdown by RNAi resulted in higher horn fly mortality (protease inhibitor functional group), reduced oviposition (vitellogenin, ferritin and vATPase groups) or both (immune response and 5'-NUC groups) when compared to controls. Silencing of ubiquitination ESTs did not affect horn fly mortality and ovisposition while gene knockdown in the ferritin and vATPse functional groups reduced mortality when compared to controls.</p> <p>Conclusions</p> <p>These results advanced the molecular characterization of this important ectoparasite and suggested candidate protective antigens for the development of vaccines for the control of horn fly infestations.</p

    Proteases of haematophagous arthropod vectors are involved in blood-feeding, yolk formation and immunity : a review

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    Ticks, triatomines, mosquitoes and sand flies comprise a large number of haematophagous arthropods considered vectors of human infectious diseases. While consuming blood to obtain the nutrients necessary to carry on life functions, these insects can transmit pathogenic microorganisms to the vertebrate host. Among the molecules related to the blood-feeding habit, proteases play an essential role. In this review, we provide a panorama of proteases from arthropod vectors involved in haematophagy, in digestion, in egg development and in immunity. As these molecules act in central biological processes, proteases from haematophagous vectors of infectious diseases may influence vector competence to transmit pathogens to their prey, and thus could be valuable targets for vectorial control

    Proteases of haematophagous arthropod vectors are involved in blood-feeding, yolk formation and immunity - a review

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    The development of oocytes of a dermacentor nuttalli tick

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    Gold-headed tick, Dermacentor nuttalli is widely distributed in Mongolia and an important vector of transovarially transmitting pathogens to domestic animals. In this study, we describe the morphology of the ovary, as well as the process of the vitellogenesis and ovigenesis on oocytes of the tick, Dermacentor nuttalli.&nbsp; The oocytes were classified into stages that varied from I to V, according to: cytoplasm appearance, presence of the germ vesicle, position, development, presence of yolk granules, accumulation and presence of chorion. To our knowledge, this study is first description on oocytes development stages evaluated by Balashov (1964) of D. nuttalli female and its vitellogenesis. Dermacentor nuttalli хачгийн ооцитын хөгжил Хураангуй:&nbsp;Цус бүрэн сорж, эвцэлдэж хувалзалсан Dermacentor nuttalli эмэгчин хачгийн ооцит, өндөгний хөгжлийг судалснаар хачгийн физиологи, биологийн онцлогийг тогтоох нь шинжлэх ухаан, онол, практикийн өндөр ач холбогдолтой юм. Энэ судалгаагаар D. nuttalli хачгийн ооцитын вителлогенез, овигенез, өндгөвчний хэлбэр зүйн хувирлыг судлан тогтоолоо. Хөгжлийн янз бүрийн шатаар хөгжиж буй ооцитуудыг цитоплазмын илрэл, герминал мөхлөгт цэврүүнцрийн илрэл, байрлал, хөгжил, уургийн мөхлөгүүдийн илрэл, хуримтлагдалт, цэлмэнт бүрхүүлийн үүсэл, хөгжлийн явцаар нь 5 шат болгон ангилав (I-V). Энэхүү судалгаа нь D. nuttalli хачгийн ооцитын хөгжлийг Ю.С.Балашов (1964)-ын үнэлгээгээр үнэлж, хөгжлийн үе шатуудыг тогтоосон анхны судалгаа юм. Түлхүүр үг: Өндгөвч, овигенез, Балашовын ангилал, вителлогене
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