A CRISPR/Cas12a-assisted rapid detection platform by biosensing the apxIVA of Actinobacillus pleuropneumoniae

Actinobacillus pleuropneumoniae is an important respiratory pig pathogen that causes substantial losses in the worldwide swine industry. Chronic or subclinical infection with no apparent clinical symptoms poses a challenge for preventing transmission between herds. Rapid diagnostics is important for the control of epidemic diseases. In this study, we formulated an A. pleuropneumoniae species-specific apxIVA-based CRISPR/Cas12a-assisted rapid detection platform (Card) that combines recombinase polymerase amplification (RPA) of target DNA and subsequent Cas12a ssDNase activation. Card has a detection limit of 10 CFUs of A. pleuropneumoniae, and there is no cross-reactivity with other common swine pathogens. The detection process can be completed in 1 h, and there was 100% agreement between the conventional apxIVA-based PCR and Card in detecting A. pleuropneumoniae in lung samples. Microplate fluorescence readout enables high-throughput use in diagnostic laboratories, and naked eye and lateral flow test readouts enable use at the point of care. We conclude that Card is a versatile, rapid, accurate molecular diagnostic platform suitable for use in both laboratory and low-resource settings

Mutations of genes in synthesis of the carotenoid precursors of ABA lead to pre-harvest sprouting and photo-oxidation in rice

Pre-harvest sprouting (PHS) or vivipary in cereals is an important agronomic trait that results in significant economic loss. A considerable number of mutations that cause PHS have been identified in several species. However, relatively few viviparous mutants in rice (Oryza sativa L.) have been reported. To explore the mechanism of PHS in rice, we carried out an extensive genetic screening and identified 12 PHS mutants (phs). Based on their phenotypes, these phs mutants were classified into three groups. Here we characterize in detail one of these groups, which contains mutations in genes encoding major enzymes of the carotenoid biosynthesis pathway, including phytoene desaturase (OsPDS), ζ-carotene desaturase (OsZDS), carotenoid isomerase (OsCRTISO) and lycopene β-cyclase (β-OsLCY), which are essential for the biosynthesis of carotenoid precursors of ABA. As expected, the amount of ABA was reduced in all four phs mutants compared with that in the wild type. Chlorophyll fluorescence analysis revealed the occurrence of photoinhibition in the photosystem and decreased capacity for eliminating excess energy by thermal dissipation. The greatly increased activities of reactive oxygen species (ROS) scavenging enzymes, and reduced photosystem (PS) II core proteins CP43, CP47 and D1 in leaves of the Oscrtiso/phs3-1 mutant and OsLCY RNAi transgenic rice indicated that photo-oxidative damage occurred in PS II, consistent with the accumulation of ROS in these plants. These results suggest that the impairment of carotenoid biosynthesis causes photo-oxidation and ABA-deficiency phenotypes, of which the latter is a major factor controlling the PHS trait in rice

Application of discrete memristors in logistic map and Hindmarsh–Rose neuron

Continuous memristor (CM) has been widely designed and applied in chaotic and neuromorphic systems. However, discrete memristor (DM) and its application are less studied. This paper reports two kinds of generalized DM model based on sampling discretization of generalized CM model. It is found that the DM models can still retain the characteristics of the CM models. Based on the proposed DM models, the Logistic map (DM-L map) and two-dimensional (2D) discrete Hindmarsh–Rose neuron model (DM-HR model) are constructed. Through multiple numerical measures, it is found that DM-L map has linear fixed points, whose stability are only related to system parameter, and that DM-HR model does not have fixed point thus can generate hidden periodic and chaotic attractors. In particular, the coexistence of point and periodic attractors with different topological structures occur in DM-L map when different initial values are taken, which are rarely reported previously. At the same time, the chaotic region becomes wider when DM is introduced into Logistic map. Therefore, we believe that DM can effectively improve chaotic complexity of Logistic map. However, in addition to hidden complex discharge phenomenon, the coexistence of periodic and chaotic attractors with different positions and shapes are observed in DM-HR model. Finally, the DSP-based hardware platform is constructed to implement these maps, and the experimental results are consistent with the numerical simulation

Preparation and fluorescence properties of MgAl2O4: Tb3+ nanorod-like phosphors

A series of MgAl _2 O _4 : x % Tb ^3+ ( x = 1.0–6.0) phosphors was prepared by a hydrothermal-assisted light burning method. The crystal structure, morphology and fluorescence properties of the samples were investigated. The results indicated that when the the hydrothermal and light burning temperatures were determined to be 120 °C and 1100 °C, respectively, the crystallinity for Mg _4 Al _2 (OH) _14 and NH _4 Al(OH) _2 CO _3 biphasic precursors is the best, conducive to generating pure phase MgAl _2 O _4 nanorod-like phosphors. The entry of Tb ^3+ into the MgAl _2 O _4 lattice can cause lattice distortion, but the main structure of the spinel does not change. The main emission peaks for the series of phosphors are located in the green light region of 546 nm. The MgAl _2 O _4 : 4.0% Tb ^3+ phosphor has the highest fluorescence intensity and shows the best colour quality. Its CIE coordinates (x, y), CCT and colour purity are determined to be (0.3171, 0.5290), 5845 K and 53.50%, respectively. The series of MgAl _2 O _4 : Tb ^3+ phosphors exhibits typical cold green light emission and have good application prospects in solid-state display devices

Complicated dynamics in a memristor-based RLC circuit

As the fourth basic circuit element, the memristor is usually employed to design chaotic circuit for the special electrical properties. This paper introduces a memristor-based RLC oscillation circuit with fourth-order differential equation. Basic dynamical properties of the system are revealed by analyzing phase portrait, time-domain waveform, Poincaré map, equilibrium point, bifurcation diagram and Lyapunov exponent. Specially, coexisting attractor with the variation of initial value is explored in this system, which means the multi-stability arises. And it is also found that there exists complicated transient dynamical behavior for some initial conditions and parameters, which completely differs from the existed modes of transient chaos and transient period

Large Cell Neuroendocrine Carcinoma Shares Similarity with Small Cell Carcinoma on the Basis of Clinical and Pathological Features

BACKGROUND: Large cell neuroendocrine carcinoma (LCNEC) was categorized into pulmonary neuroendocrine tumors (NETs) according to the World Health Organization classification guideline. However, LCNEC patients often received the chemotherapy regimens similar to non-small cell lung carcinoma (NSCLC) in advanced stage and the therapeutic effect was unsatisfactory. Therefore, this study aimed to investigate the hidden clinical features, prognosis and immunoprofile of the LCNEC, compared with carcinoid and SCLC, to explore whether LCNEC shares similarity with SCLC and potential treatment approaches could be revealed. METHODS: One hundred seventeen pulmonary NETs cases were retrospectively retrieved in this study. The Kaplan–Meier estimator was employed to draw survival curves. Immunohistochemistry was applied to detect NET-related markers expression. RESULTS: In clinical features, compared with carcinoid, LCNEC patients were older, more commonly in male and advanced stage. The parallel phenomena were also found in the high-grade subgroup when compared with the low- to intermediate-grade one. In survival analysis, the 5-year overall survival of LCNECs was 59.1%, which was poorer than that of carcinoids, but better than that of SCLCs. Immunohistochemistry showed that p53 and PTEN functional inactivation, up-regulation of CD117 expression, down-regulation of SSR2A and SSR5 expression were commonly involved in LCNECs when compared with carcinoids, or in the high-grade subgroup when compared with the low- to intermediate-grade one. However, no significant difference was found in the comparison between LCNECs and SCLCs, or NSCLCs and SCLCs. CONCLUSION: In clinical features, survival and immunoprofile, LCNEC showed more similarity with SCLC rather than carcinoid, which might guide novel therapy for pulmonary NETs

Broad protective immune responses elicited by bacterium-like particle-based intranasal pneumococcal particle vaccine displaying PspA2 and PspA4 fragments

Streptococcus pneumoniae is an infectious pathogen mainly infecting host bodies through the respiratory system. An effective pneumococcal vaccine would be targeted to the mucosa and provide not only protection against invasive infection but also against colonization in the respiratory system. In the present work, we applied bacterium-like particles (BLPs) as an adjuvant for the development of a PspA mucosal vaccine, in which the PspA protein was displayed on the surface of BLPs. Intranasal immunization with the PspA-BLP pneumococcal vaccine, comprised of PspA2 from pneumococcal family 1 and PspA4 from pneumococcal family 2, not only induced a high level of serum IgG antibodies but also a high level of mucosal SIgA antibodies. Analysis of binding of serum antibodies to intact bacteria showed a broad coverage of binding to pneumococcal strains expressing PspA from clade 1 to 5. Immunization with the PspA-BLP vaccine conferred protection against fatal intranasal challenge with both PspA family 1 and family 2 pneumococcal strains regardless of serotype. Therefore, the PspA-BLP pneumococcal vaccine was demonstrated to be a promising strategy for mucosal immunization to enhance both systemic and mucosal immune responses