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81.
Merilaita S 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2007,362(1479):421-430
In this paper, I investigate the use of artificial neural networks in the study of prey coloration. I briefly review the anti-predator functions of prey coloration and describe both in general terms and with help of two studies as specific examples the use of neural network models in the research on prey coloration. The first example investigates the effect of visual complexity of background on evolution of camouflage. The second example deals with the evolutionary choice of defence strategy, crypsis or aposematism. I conclude that visual information processing by predators is central in evolution of prey coloration. Therefore, the capability to process patterns as well as to imitate aspects of predator's information processing and responses to visual information makes neural networks a well-suited modelling approach for the study of prey coloration. In addition, their suitability for evolutionary simulations is an advantage when complex or dynamic interactions are modelled. Since not all behaviours of neural network models are necessarily biologically relevant, it is important to validate a neural network model with empirical data. Bringing together knowledge about neural networks with knowledge about topics of prey coloration would provide a potential way to deepen our understanding of the specific appearances of prey coloration. 相似文献
82.
83.
Prevalence and Risk Factors of Helicobacter pylori Infection in Saudi Children: A Three‐Year Prospective Controlled Study 下载免费PDF全文
84.
A Sami Saribas Kamel Khalili Ilker Kudret Sariyer 《Cell cycle (Georgetown, Tex.)》2015,14(18):2899-2904
Viruses often exploit autophagy, a common cellular process of degradation of damaged proteins, organelles, and pathogens, to avoid destruction. HIV-1 dysregulates this process in several cell types by means of Nef protein. Nef is a small HIV-1 protein which is expressed abundantly in astrocytes of HIV-1-infected brains and has been suggested to have a role in the pathogenesis of HIV-Associated Neurocognitive Disorders (HAND). In order to explore its effect in the CNS with respect to autophagy, HIV-1 Nef was expressed in primary human fetal astrocytes (PHFA) using an adenovirus vector (Ad-Nef). We observed that Nef expression triggered the accumulation of autophagy markers, ATG8/LC3 and p62 (SQSMT1). Similar results were obtained with Bafilomycin A1, an autophagy inhibitor which blocks the fusion of autophagosome to lysosome. Furthermore co-expression of tandem LC3 vector (mRFP-EGFP-LC3) and Ad-Nef in these cells produced mainly yellow puncta (mRFP+, EGFP+) strongly suggesting that autophagosome fusion to lysosome is blocked in PHFA cells in the presence of Nef. Together these data indicate that HIV-1 Nef mimics Bafilomycin A1 and blocks the last step of autophagy thereby helping HIV-1 virus to avoid autophagic degradation in human astrocytes. 相似文献
85.
Lakard B Magnin D Deschaume O Vanlancker G Glinel K Demoustier-Champagne S Nysten B Jonas AM Bertrand P Yunus S 《Biosensors & bioelectronics》2011,26(10):4139-4145
A potentiometric biosensor based on urease was developed for the quantitative determination of urea concentration in aqueous solutions for biomedical applications. The urease was either physisorbed onto an electrodeposited polyaniline film (PANI), or immobilized on a layer-by-layer film (LbL) assembled over the PANI film, that was obtained by the alternate deposition of charged polysaccharides (carboxymethylpullulan (CMP) and chitosan (CHI)). In the latter case, the urease (Urs) enzyme was either physically adsorbed or covalently grafted to the LbL film using carbodiimide coupling reaction. Potentiometric responses of the enzymatic biosensors were measured as a function of the urea concentration in aqueous solutions (from 10(-6) to 10(-1) mol L(-1) urea). Very high sensitivity and short response time were observed for the present biosensor. Moreover, a stability study showed a higher stability over time for the potentiometric response of the sensor with the enzyme-grafted LbL film, testifying for the protective nature of the polysaccharide coating and the interest of covalent grafting. 相似文献
86.
Butyl acetate holds great potential as a sustainable biofuel additive. Heterogeneously catalyzed transesterification of biobutanol and bioethylacetate can produce butyl acetate. This route is eco-friendly and offers several advantages over the commonly used Fischer Esterification. The Amberlite IR 120- and Amberlyst 15-catalyzed transesterification is studied in a batch reactor over a range of catalyst loading (6–12 wt.%), alcohol to ester feed ratio (1:3 to 3:1), and temperature (303.15–333.15 K). A butanol mole fraction of 0.2 in the feed is found to be optimum. Amberlite IR 120 promotes faster kinetics under these conditions. The transesterifications studied are slightly exothermic. The moles of solvent sorbed per gram of catalyst decreases (ethanol > butanol > ethyl acetate > butyl acetate) with decrease in solubility parameter. The dual site models, the Langmuir Hinshelwood and Popken models, are the most successful in correlating the kinetics over Amberlite IR 120 and Amberlyst 15, respectively. 相似文献
87.
Teyeb H Zouari S Douki W Najjar MF Neffati M 《Zeitschrift für Naturforschung. C, Journal of biosciences》2011,66(1-2):1-6
The essential oils obtained by hydrodistillation (Clevenger apparatus) from aerial parts of Astragalus gombiformis were analysed by gas chromatography coupled with mass spectrometry (GC/MS). This study showed that the A. gombiformis essential oils are complex mixtures of important natural compounds, which varied qualitatively and quantitatively between cultivated and wild plants and between phenological stages of development. All analysed oils are characterized by the constant presence of phytol, 6,10,14-trimethyl-2-pentadecanone, 4-terpineol, and gamma-terpinene. This study is the first report on the chemical composition of essential oils from A. gombiformis and indicates that these oils should be more studied. 相似文献
88.
Šilhár P Alakurtti S Čapková K Xiaochuan F Shoemaker CB Yli-Kauhaluoma J Janda KD 《Bioorganic & medicinal chemistry letters》2011,21(8):2229-2231
Botulinum neurotoxins (BoNTs) are the most toxic proteins currently known. Current treatments for botulinum poisoning are all protein based with a limited window of opportunity. Inhibition of the BoNT light chain protease (LC) has emerged as a new therapeutic strategy for the treatment of botulism as it may provide an effective post-exposure remedy. As such, a small library of 40 betulin derivatives was synthesized and screened against the light chain of BoNT serotype A (LC/A); five positive hits (IC50 <100 μM) were uncovered. Detailed evaluation of inhibition mechanism of three most active compounds revealed a competitive model, with sub-micromolar Ki value for the best inhibitor (7). Unfortunately, an in vitro cell-based assay did not show any protection of rat cerebellar neurons against BoNT/A intoxication by 7. 相似文献
89.
Varisli L Gonen-Korkmaz C Debelec-Butuner B Erbaykent-Tepedelen B Muhammed HS Bogurcu N Saatcioglu F Korkmaz KS 《DNA and cell biology》2011,30(6):419-429
As the molecular mechanism of β-catenin deregulation is not well understood, and stabilized β-catenin is known to translocate into the nucleus and activate genes for proliferation, a novel regulatory factor, hematological and neurological expressed 1 (HN1), for Akt-GSK3β-β-catenin axis is reported here. In our studies, HN1 gene structure was characterized. HN1 expression was found to be epidermal growth factor-responsive in PC-3 cells, and protein expression was also upregulated in PC-3 and LNCaP but not in DU145 cells. Additionally, HN1 was found to be downregulated by the specific AKT inhibitor wortmannin but not with PI3K or MAPK inhibitors, LY294002 and PD98059, respectively, in PC-3 and MCF-7 cells. Further, siRNA-mediated knockdown of HN1 resulted in considerable increase in Akt((S473)) and GSK3β((S9),(Y216)) phosphorylations; moreover, subsequent accumulation of β-catenin, increase in c-myc expression, and nuclear accumulation of cyclin D1 were observed in PC-3 cells. Knockdown of HN1 also resulted in prolongation of G(1) phase in cell cycle, increasing tetraploidy, presumably because of cells escaping from abnormal mitosis in PC-3 cells. Consistently, overexpression of HN1 reversed the cell-cycle-specific observations, resulted in accumulation of cells in G(2)/M, and reduced the proliferation rate, which were investigated using flow cytometry and methylthiazol tetrazolium assays. As activating mutations of β-catenin have been demonstrated in late-stage tumors, and β-catenin stabilization was correlated with poor prognosis in previous reports, epidermal growth factor-upregulated HN1 expression might have a role in deregulating the AKT-GSK3β((S9))-mediated signaling as a novel compensating mechanism. 相似文献
90.
Sayyed A Hamidi Richard Z Lin Anthony M Szema Sergey Lyubsky Ya Ping Jiang Sami I Said 《Respiratory research》2011,12(1):141