Inorganic Perovskite Quantum Dot-Mediated Photonic Multimodal Synapse.

Artificial synapse is the basic unit of a neuromorphic computing system. However, there is a need to explore suitable synaptic devices for the emulation of synaptic dynamics. This study demonstrates a photonic multimodal synaptic device by implementing a perovskite quantum dot charge-trapping layer in the organic poly(3-hexylthiophene-2,5-diyl) (P3HT) channel transistor. The proposed device presents favorable band alignment that facilitates spatial separation of photogenerated charge carriers. The band alignment serves as the basis of optically induced charge trapping, which enables nonvolatile memory characteristics in the device. Furthermore, high photoresponse and excellent synaptic characteristics, such as short-term plasticity, long-term plasticity, excitatory postsynaptic current, and paired-pulse facilitation, are obtained through gate voltage regulation. Photosynaptic characteristics obtained from the device showed a multiwavelength response and a large dynamic range (∼103) that is suitable for realizing a highly accurate artificial neural network. Moreover, the device showed nearly linear synaptic weight update characteristics with incremental depression electric gate pulse. The simulation based on the experimental data showed excellent pattern recognition accuracy (∼85%) after 120 epochs. The results of this study demonstrate the feasibility of the device as an optical synapse in the next-generation neuromorphic system.

Two Liberibacter Proteins Combine to Suppress Critical Innate Immune Defenses in Citrus.

We adopted a systems-based approach to determine the role of two Candidatus Liberibacter asiaticus (CLas) proteins, LasP 235 and Effector 3, in Huanglongbing (HLB) pathogenesis. While a published work suggests the involvement of these CLas proteins HLB pathogenesis, the exact structure-based mechanism of their action has not been elucidated. We conducted the following experiments to determine the structure-based mechanisms of action. First, we immunoprecipitated the interacting citrus protein partners of LasP 235 and Effector 3 from the healthy and CLas-infected Hamlin extracts and identified them by Liquid Chromatography with tandem mass spectrometry (LC-MS/MS). Second, we performed a split green fluorescent protein (GFP) assay in tobacco to validate that the interactions observed in vitro are also retained in planta. The notable in planta citrus targets of LasP 235 and Effector 3 include citrus innate immune proteins. Third, in vitro and in planta studies were performed to show that LasP 235 and Effector 3 interact with and inhibit the functions of multiple citrus proteins belonging to the innate immune pathways. These inhibitory interactions led to a high level of reactive oxygen species, blocking of bactericidal lipid transfer protein (LTP), and induction of premature programed cell death (PCD), all of which are beneficial to CLas lifecycle and HLB pathogenesis. Finally, we performed molecular dynamics simulations to visualize the interactions of LasP 235 and Effector 3, respectively, with LTP and Kunitz protease inhibitor. This led to the design of an LTP mimic, which sequestered and blocked LasP 235 and rescued the bactericidal activity of LTP thereby proving that LasP 235 , indeed, participates in HLB pathogenesis.

Characterization of organophosphate pesticide sorption of potato peel biochar as low cost adsorbent for chlorpyrifos removal.

There has been a growing interest in the scientific world in the production of biochar from natural organic wastes as potential sustainable precursors for bioremediation. Potato peel biochar was produced by slow pyrolysis method under oxygen-limited conditions and used as bio adsorbent in bioremediation of commercial pesticide having Chlorpyrifos as an active component. Chlorpyrifos is an organophosphate pesticide, highly neurotoxic, and primarily targets the central nervous system of pests and insects. The excess residues of chlorpyrifos are hazardous to environmental flora and fauna. Chlorpyrifos was treated against biochar at varying physical parameters and further optimized by using response surface methodology through Box-Behnken design (BBD). 72.06% of pesticide removal was observed post 24 h of treatment against a pesticide concentration of 1346.85 µg/ml with a biochar concentration of 1.04 mg/ml under room temperature at pH 5.04. Biochar was characterized by proximate and ultimate analysis, FTIR, and SEM-EDX. Characterization by SEM-EDX showed the surface morphology and minerals on the peel and biochar. Microgram of potato peel shows pores of larger size than biochar having many cavities with different dimensions. In the plant system, growth morphology, nutritional status, polyphenols, total antioxidant content, and free radical scavenging activity were assessed. Enhancement in presence of biochar was recorded in growth morphology and plant biomolecules including photosynthetic pigments. Better translocation of the nutrient is recorded in biochar treated plants, as evidenced by the low amount of carbohydrate and protein in treated leaves. Biocompatibility assessment of chlorpyriphos in fish erythrocytes showed 43.26% hemolysis by pesticide-treated biochar. The practical use of this approach can also be best utilized if applied to those geographical regions where the soil pH is acidic. Biochar is a marketable bio-product, which can have a positive impact in agriculture, industries, and the energy sector creating a bio-based economy with reduced environmental pollution.

Host-derived chimeric peptides clear the causative bacteria and augment host innate immunity during infection: A case study of HLB in citrus and fire blight in apple.

Bacterial diseases cause severe losses in the production and revenue of many fruit crops, including citrus and apple. Huanglongbing (HLB) in citrus and fire blight in apple are two deadly diseases without any cure. In this article, we introduce a novel therapy for HLB and fire blight by enhancing the innate immunity of the host plants. Specifically, we constructed in silico a library of chimeras containing two different host peptides with observed or predicted antibacterial activity. Subsequently, we performed bactericidal and toxicity tests in vitro to select a few non-toxic chimeras with high antibacterial activity. Finally, we conducted ex planta studies to show that not only do the chimeras clear the causative bacteria from citrus leaves with HLB and from apple leaves with fire blight but they also augment the host's innate immunity during infection. This platform technology can be extended to design host-derived chimeras against multiple pathogenic bacteria that cause diseases in plants and animals of agricultural importance and in humans.

Rational design of antimicrobial peptides targeting Gram-negative bacteria.

Membrane-targeting host antimicrobial peptides (AMPs) can kill or inhibit the growth of Gram-negative bacteria. However, the evolution of resistance among microbes poses a substantial barrier to the long-term utility of the host AMPs. Combining experiment and molecular dynamics simulations, we show that terminal carboxyl capping enhances both membrane insertion and antibacterial activity of an AMP called P1. Furthermore, we show that a bacterial strain with evolved resistance to this peptide becomes susceptible to P1 variants with either backbone capping or lysine-to-arginine substitutions. Our results suggest that cocktails of closely related AMPs may be useful in overcoming evolved resistance.

An in vitro protocol for rapidly assessing the effects of antimicrobial compounds on the unculturable bacterial plant pathogen, Candidatus Liberibacter asiaticus.

BACKGROUND: Most bacteria are not culturable, but can be identified through molecular methods such as metagenomics studies. Due to specific metabolic requirements and symbiotic relationships, these bacteria cannot survive on typical laboratory media. Many economically and medically important bacteria are unculturable; including phloem-limited plant pathogens like Candidatus Liberibacter asiaticus (CLas). CLas is the most impactful pathogen on citrus production, is vectored by the Asian citrus psyllid (ACP, Diaphorina citri), and lacks an effective treatment or resistant cultivars. Research into CLas pathogenicity and therapy has been hindered by the lack of persistent pure cultures. Work to date has been mostly limited to in planta studies that are time and resource intensive. RESULTS: We developed and optimized an in vitro protocol to quickly test the effectiveness of potential therapeutic agents against CLas. The assay uses intact bacterial cells contained in homogenized tissue from CLas-infected ACP and a propidium monoazide (PMA) assay to measure antimicrobial activity. The applicability of PMA was evaluated; with the ability to differentiate between intact and disrupted CLas cells confirmed using multiple bactericidal treatments. We identified light activation conditions to prevent PCR interference and identified a suitable positive control for nearly complete CLas disruption (0.1% Triton-X 100). Isolation buffer components were optimized with 72 mM salt mixture, 1 mM phosphate buffer and 1% glycerol serving to minimize unwanted interactions with treatment and PMA chemistries and to maximize recovery of intact CLas cells. The mature protocol was used to compare a panel of peptides already under study for potential CLas targeting bactericidal activity and identify which were most effective. CONCLUSION: This psyllid homogenate assay allows for a quick assessment of potential CLas-disrupting peptides. Comparison within a uniform isolate largely eliminates experimental error arising from variation in CLas titer between and within individual host organisms. Use of an intact vs. disrupted assay permits direct assessment of potential therapeutic compounds without generating pure cultures or conducting extensive in planta or field studies.

Experimental process parameters optimization and in-depth product characterizations for teak sawdust pyrolysis.

Pyrolysis is an efficient thermochemical route to obtain biofuels in the form of bio-oil, biochar and pyrolytic gas from the processing of biomass. Pyrolysis experiments were performed with teak sawdust to determine the yield and main characteristics of solid, liquid and gaseous products. Experiments were carried out in the temperature range of 400-700 °C in 100 °C intervals, nitrogen flow rate of 150-250 mL/min, packed bed height in between 2 and 8 cm and particle size in between 0.18 and 0.60 mm. The maximum bio-oil and biochar yield were observed at 600 °C (48.8%) and 400 °C (37.42%), respectively. Physical properties (viscosity, density, carbon residue, pH and HHV) of bio-oil were determined and the chemical properties were investigated using FTIR and GC-MS. Further, biochar was characterized with proximate, ultimate, HHV, FTIR, SEM-EDX, BET surface area and XRD analysis. Non-condensable gases coming out during pyrolysis were analyzed using gas chromatography and amount of H2, CH4, CO and CO2 were determined. According to characterization results, bio-oil can be used as biofuel after up gradation or as source of valuable chemicals, biochar can be utilized as solid fuel or seems to be suitable in waste stream purification as it has very high BET surface area. In addition, pyrolytic gases have significant amount of methane and hydrogen that provides good combustion properties.

Pretreatment optimisation and kinetics of batch anaerobic digestion of liquidised OFMSW treated with NaOH: Models verification with experimental data.

The enormous generation of municipal solid waste (MSW) due to increased urbanization is causing threat to the environment. MSW is a mixed waste and it comprises of organic fraction as the key fraction called organic fraction of municipal solid waste (OFMSW) along with other fractions. The pretreatment of OFMSW is necessary step to increase the biogas yield. In the present work, NaOH hydrolysis of mechanically liquidised OFMSW was carried out to reduce its complexity and improve the biogas production. Furthermore, hydrolysis parameters were optimised by RSM model for NaOH pretreatment. Optimised conditions achieved from RSM analysis were 0.46 N NaOH loading, 72 h reaction time and 36.05 °C operating temperature. The RSM predicted values of response sCOD and VFA at optimum condition were in good agreement with experimental data signifying the model adequacy. The kinetic of batch anaerobic digestion of OFMSW treated with NaOH at different concentrations and optimised condition had been studied to see the suitability of first order model and modified Gompartz model. The experimental results obtained were best fitted using normalized root mean square error analysis. Biogas production after pretreatment at 0.1, 0.5, 0.9 N NaOH concentration and RSM optimised condition was 369.24, 435.24, 327.84 and 465.67 NL/kg VS, respectively.

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1-xZnxFe2O4/NBR Composites over 2-12.4 GHz: A Strategic Material System for Stealth Applications.

The gel to carbonate precipitate route has been used for the synthesis of Ni1-xZnxFe2O4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > -1.2 over the entire 2-10 GHz frequency range with an optimum value ~-1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications.

Overexpression of a Modified Plant Thionin Enhances Disease Resistance to Citrus Canker and Huanglongbing (HLB).

Huanglongbing (HLB or citrus greening disease) caused by Candidatus Liberibacter asiaticus (Las) is a great threat to the US citrus industry. There are no proven strategies to eliminate HLB disease and no cultivar has been identified with strong HLB resistance. Citrus canker is also an economically important disease associated with a bacterial pathogen (Xanthomonas citri). In this study, we characterized endogenous citrus thionins and investigated their expression in different citrus tissues. Since no HLB-resistant citrus cultivars have been identified, we attempted to develop citrus resistant to both HLB and citrus canker through overexpression of a modified plant thionin. To improve effectiveness for disease resistance, we modified and synthesized the sequence encoding a plant thionin and cloned into the binary vector pBinPlus/ARS. The construct was then introduced into Agrobacterium strain EHA105 for citrus transformation. Transgenic Carrizo plants expressing the modified plant thionin were generated by Agrobacterium-mediated transformation. Successful transformation and transgene gene expression was confirmed by molecular analysis. Transgenic Carrizo plants expressing the modified thionin gene were challenged with X. citri 3213 at a range of concentrations, and a significant reduction in canker symptoms and a decrease in bacterial growth were demonstrated compared to nontransgenic plants. Furthermore, the transgenic citrus plants were challenged with HLB via graft inoculation. Our results showed significant Las titer reduction in roots of transgenic Carrizo compared with control plants and reduced scion Las titer 12 months after graft inoculation. These data provide promise for engineering citrus disease resistance against HLB and canker.

Complete Genome Sequence of "Candidatus Liberibacter africanus," a Bacterium Associated with Citrus Huanglongbing.

We report here the complete genome sequence of "Candidatus Liberibacter africanus" strain PTSAPSY. The 1,192,232-bp genome with 34.5% G+C content comprises 1,017 open reading frames, 44 tRNAs, and three complete rRNAs in a circular chromosome.

Complete Genome Sequence of a Chinese Strain of "Candidatus Liberibacter asiaticus".

We report here the complete genome sequence of "Candidatus Liberibacter asiaticus" (strain Guangxi-1). The 1,268,237-bp genome with a 36.5% G+C content comprises 1,141 open reading frames, 44 tRNAs, and 3 complete rRNAs in a circular chromosome.

Crystal structure of AcrB complexed with linezolid at 3.5 Å resolution.

AcrB is an inner membrane resistance-nodulation-cell division efflux pump and is part of the AcrAB-TolC tripartite efflux system. We have determined the crystal structure of AcrB with bound Linezolid at a resolution of 3.5 Å. The structure shows that Linezolid binds to the A385/F386 loops of the symmetric trimer of AcrB. A conformational change of a loop in the bottom of the periplasmic cleft is also observed.

Draft Genome Sequence of "Candidatus Liberibacter americanus" Bacterium Associated with Citrus Huanglongbing in Brazil.

We report here the draft genome sequence of "Candidatus Liberibacter americanus" strain PW_SP. The 1,176,071-bp genome, with 31.6% G+C content, comprises 948 open reading frames, 38 tRNAs, and three complete rRNAs.

An engineered innate immune defense protects grapevines from Pierce disease.

We postulated that a synergistic combination of two innate immune functions, pathogen surface recognition and lysis, in a protein chimera would lead to a robust class of engineered antimicrobial therapeutics for protection against pathogens. In support of our hypothesis, we have engineered such a chimera to protect against the gram-negative Xylella fastidiosa (Xf), which causes diseases in multiple plants of economic importance. Here we report the design and delivery of this chimera to target the Xf subspecies fastidiosa (Xff), which causes Pierce disease in grapevines and poses a great threat to the wine-growing regions of California. One domain of this chimera is an elastase that recognizes and cleaves MopB, a conserved outer membrane protein of Xff. The second domain is a lytic peptide, cecropin B, which targets conserved lipid moieties and creates pores in the Xff outer membrane. A flexible linker joins the recognition and lysis domains, thereby ensuring correct folding of the individual domains and synergistic combination of their functions. The chimera transgene is fused with an amino-terminal signal sequence to facilitate delivery of the chimera to the plant xylem, the site of Xff colonization. We demonstrate that the protein chimera expressed in the xylem is able to directly target Xff, suppress its growth, and significantly decrease the leaf scorching and xylem clogging commonly associated with Pierce disease in grapevines. We believe that similar strategies involving protein chimeras can be developed to protect against many diseases caused by human and plant pathogens.

Induction of cytokines and chemokines by Toll-like receptor signaling: strategies for control of inflammation.

Recognition of the pathogen-associated molecular pattern (PAMP) by host Toll-like receptors (TLR) is an important component of the innate immune response for countering against invading viruses, bacteria, and fungi. Upon PAMP recognition, the TLR induces intracellular signaling cascades that involve adapter, signalosome, and transcription factor complexes and result in the production of both pro- and anti-inflammatory cytokines and chemokines. An inflammatory response for a short duration can be beneficial because it helps to clear the infectious agent. However, prolonged inflammation can be detrimental because it may cause host toxicity and tissue damage. Indeed, excessive production of inflammatory cytokines and chemokines via TLR pathways is often associated with many inflammatory and autoimmune diseases. Therefore, fine control of inflammation in the TLR pathway is highly desirable for effective host defense. In this article, we review intrinsic control mechanisms that include a balance between pro-inflammatory and anti-inflammatory cytokines and chemokines, production of host effectors, and regulation at the level of adapter, signalosome, and transcription factor complexes in the TLR pathways. We also discuss how understanding of the TLR signaling steps leads to the development of small-molecule drugs that can interfere with the formation of active adapter, signalosome, and adapter complexes.

Analysis of early host responses for asymptomatic disease detection and management of specialty crops.

The rapid and unabated spread of vector-borne diseases within US specialty crops threatens our agriculture, our economy, and the livelihood of growers and farm workers. Early detection of vector-borne pathogens is an essential step for the accurate surveillance and management of vector-borne diseases of specialty crops. Currently, we lack the tools that would detect the infectious agent at early (primary) stages of infection with a high degree of sensitivity and specificity. In this paper, we outline a strategy for developing an integrated suite of platform technologies to enable rapid, early disease detection and diagnosis of huanglongbing (HLB), the most destructive citrus disease. The research has two anticipated outcomes: i) identification of very early, disease-specific biomarkers using a knowledge base of translational genomic information on host and pathogen responses associated with early (asymptomatic) disease development; and ii) development and deployment of novel sensors that capture these and other related biomarkers and aid in presymptomatic disease detection. By combining these two distinct approaches, it should be possible to identify and defend the crop by interdicting pathogen spread prior to the rapid expansion phase of the disease. We believe that similar strategies can also be developed for the surveillance and management of diseases affecting other economically important specialty crops.

Beryllium alters lipopolysaccharide-mediated intracellular phosphorylation and cytokine release in human peripheral blood mononuclear cells.

Beryllium exposure in susceptible individuals leads to the development of chronic beryllium disease, a lung disorder marked by release of inflammatory cytokine and granuloma formation. We have previously reported that beryllium induces an immune response even in blood mononuclear cells from healthy individuals. In this study, we investigate the effects of beryllium on lipopolysaccharide-mediated cytokine release in blood mononuclear and dendritic cells from healthy individuals. We found that in vitro treatment of beryllium sulfate inhibits the secretion of lipopolysaccharide-mediated interleukin 10, while the release of interleukin 1beta is enhanced. In addition, not all lipopolysaccharide-mediated responses are altered, as interleukin 6 release in unaffected upon beryllium treatment. Beryllium sulfate-treated cells show altered phosphotyrosine levels upon lipopolysaccharide stimulation. Significantly, beryllium inhibits the phosphorylation of signal transducer and activator of transducer 3, induced by lipopolysaccharide. Finally, inhibitors of phosphoinositide-3 kinase mimic the effects of beryllium in inhibition of interleukin 10 release, while they have no effect on interleukin 1beta secretion. This study strongly suggests that prior exposures to beryllium could alter host immune responses to bacterial infections in healthy individuals, by altering intracellular signaling.

A dual-purpose protein ligand for effective therapy and sensitive diagnosis of anthrax.

This article reports the design of a bivalent protein ligand with dual use in therapy and diagnosis of anthrax caused by Bacillus anthracis. The ligand specifically binds to PA and thereby blocks the intracellular delivery of LF and EF toxins that, respectively, cause cell lysis and edema. The ligand is a chimeric scaffold with two PA-binding domains (called VWA) linked to an IgG-Fc frame. Molecular modeling and binding measurements reveal that the VWA-Fc dimer binds to PA with high affinity (K(D)=0.2 nM). An in vitro bio-luminescence assay shows that VWA-Fc (at nanomolar concentration) protects mouse macrophages from lysis by PA/LF. In vivo studies demonstrate that VWA-Fc at low doses (approximately 50 microg/animal) are able to rescue animals from lethal doses of PA/LF and B. anthracis spores. Finally, VWA-Fc is utilized as the capture molecule in the sensitive (down to 30 picomolar) detection of PA using surface plasmon resonance.

Pathogen-specific innate immune response.

This chapter summarizes our studies on the three toll-like receptor pathways, namely TLR4, TLR2, and TLR3, induced by lipopolysaccharides (LPS), peptidoglycan (PGN), and double-stranded RNA (dsRNA) in antigen presenting cells (APC). The particular emphasis is on the activation of human innate immune responses via cytokine and chemokine production. Three different measurements have been performed on monocytic and dendritic cells as model APCs: (i) the expression of various cytokine and chemokine genes by real-time PCR, (ii) the release of the cytokines and chemokines by ELISA, and (iii) gene expression analysis by cytokine and chemokine pathway-specific and whole genome microarrays. Real-time PCR and ELISA enable us to identify cytokines and chemokines that are produced specifically upon LPS, PGN, or dsRNA stimulation. Subsequently, microarray studies and appropriate validation experiments help us to identify genes involved in the upstream pathways that cause the induction of cytokines and chemokines. It is evident that TLR4-LPS, TLR2-PGN, and TLR3-dsRNA pathways are distinguished by the specific set of cytokines and chemokines they induce as well as by the upstream signaling events.