Stigma receptors control intraspecies and interspecies barriers in Brassicaceae.

Flowering plants have evolved numerous intraspecific and interspecific prezygotic reproductive barriers to prevent production of unfavourable offspring1. Within a species, self-incompatibility (SI) is a widely utilized mechanism that rejects self-pollen2,3 to avoid inbreeding depression. Interspecific barriers restrain breeding between species and often follow the SI × self-compatible (SC) rule, that is, interspecific pollen is unilaterally incompatible (UI) on SI pistils but unilaterally compatible (UC) on SC pistils1,4-6. The molecular mechanisms underlying SI, UI, SC and UC and their interconnections in the Brassicaceae remain unclear. Here we demonstrate that the SI pollen determinant S-locus cysteine-rich protein/S-locus protein 11 (SCR/SP11)2,3 or a signal from UI pollen binds to the SI female determinant S-locus receptor kinase (SRK)2,3, recruits FERONIA (FER)7-9 and activates FER-mediated reactive oxygen species production in SI stigmas10,11 to reject incompatible pollen. For compatible responses, diverged pollen coat protein B-class12-14 from SC and UC pollen differentially trigger nitric oxide, nitrosate FER to suppress reactive oxygen species in SC stigmas to facilitate pollen growth in an intraspecies-preferential manner, maintaining species integrity. Our results show that SRK and FER integrate mechanisms underlying intraspecific and interspecific barriers and offer paths to achieve distant breeding in Brassicaceae crops.

Plasma levels of hydrogen sulfide and homocysteine correlate with the efficacy of antidepressant agents and serve as potential diagnostic and therapeutic markers.

OBJECTIVE: Hydrogen sulfide (H2S) is associated with depressive-like behavior in rodents. We undertook cross-sectional and longitudinal analyses of plasma levels of H2S and its substrate homocysteine (Hcy) in depression and assessed the association of both parameters with psychopathology and cognitive function. METHODS: Forty-one patients suffering from depression (PSDs) and 48 healthy volunteers were recruited. PSDs were treated for 8 weeks. Analyzable data were collected from all participants for assessment of their psychopathology and cognitive function. Plasma was collected for determination of levels of H2S and Hcy, and data were correlated to determine their potential as plasma biomarkers. RESULTS: Cross-sectional analyses revealed PSDs to have a low plasma H2S level and high Hcy level. Longitudinal analyses revealed that 8 weeks of treatment reversed the changes in plasma levels of H2S and Hcy in PSDs. Plasma levels of H2S and Hcy were associated with psychopathology and cognitive function in depression. The area under the receiver operating characteristic curve (AUC) for a combination of plasma levels of H2S and Hcy and expression of the TNF gene (i.e., H2S-Hcy-TNF) was 0.848 for diagnosing depression and 0.977 for predicting the efficacy of antidepressant agents. CONCLUSION: Plasma levels of H2S and Hcy reflect changes in psychopathology and cognitive function in depression and H2S-Hcy-TNF has the potential to diagnose depression and predict the efficacy of antidepressant medications.

Plasma exosomes lncRNA-miRNA-mRNA network construction and its diagnostic efficacy identification in first-episode schizophrenia.

BACKGROUND: The exosomal lncRNA-miRNA-mRNA networks in first episode schizophrenia (FOS) have not reported yet. This study examined the lncRNA, miRNA and mRNA expression level in exosome derived from first episode schizophrenia (FOS) patients, and explored the the potential of exosomes as biomarkers for schizophrenia. METHODS: We recruited 10 FOS patients and healthy controls (HCs) respectively, examined the lncRNA, miRNA and mRNA expression level of plasma exosome by high throughput sequencing, constructed lncRNA-miRNA-mRNA network, and performed correlation analysis, GO and KEGG pathway analysis, PPI network construction and ROC analysis. RESULTS: There were 746 differently expressed lncRNA, 22 differently expressed miRNA, and 2637 differently expressed mRNA in plasma exosome in FOS compared with HCs. Then we constructed ceRNA network consisting of 8 down-regulated lncRNA, 7 up-regulated miRNA and 65 down-regulated mRNA, and 1 up-regulated lncRNA, 1 down-regulated miRNA and 4 up-regulated mRNA. The expression level of 1 lncRNA and 7 mRNA in exosomal network were correlated with PANSS score. GO and KEGG pathway analysis showed that 4 up-regulated mRNAs were enriched in neuropsychiatric system function. Down-regulated mRNA EZH2 and SIRT1 were identified as hub gene. Finally, we detected the ROC curve of ENSG00000251562, miR-26a-5p, EZH2, miR-22-3p, SIRT1, ENSG00000251562-miR-26a-5p-EZH2, ENSG00000251562-miR-22-3p-SIRT1, and found that the AUC of ceRNA network was higher than lncRNA, miRNA and mRNA alone. CONCLUSION: We constructed the lncRNA-miRNA-mRNA network in exosome derived from FOS plasma, and found that lncRNA-miRNA-mRNA network has potential as biomarkers for FOS.

Ultralong and Color-Tunable Room-Temperature Phosphorescence Based on Commercial Melamine for Anticounterfeiting and Information Recognition.

Advances have been made in the research on color-tunable organic ultralong room-temperature phosphorescence (OURTP) materials. Due to the high cost of raw materials, complex and strict synthesis conditions, and low yields, it is hard to obtain cheap commercial OURTP materials within a short time. Therefore, it is of practical significance to research and develop new OURTP functions based on commercialized organic materials. In this study, the OURTP characteristics of melamine (MEL), a kind of commercially available, cheap, and pure organic material, were investigated and explored. MEL was found with color-tunable and excellent OURTP, the average lifetime can reach 0.74 s, and the phosphorescence quantum yield can reach 17%. Since the ratio of molecular phosphorescence of MEL to the ultralong phosphorescence mediated by H-aggregation differs with the excitation wavelength and their luminescence life spans are also different, the color of OURTP materials is dependent on both excitation wavelength and time. Moreover, the OURTP characteristics of MEL can be utilized in anticounterfeiting and information identification.

Preparation of Single-Stranded DNA-Templated Room-Temperature Phosphorescent Quantum Dots and Their Application for Mercury(II) Detection in Environmental and Biological Fluids.

The direction synthesis of biofunctional nanomaterials with DNA as the template is of high application value. By using phosphorothioate-thymine single-stranded DNA (PS-T-ssDNA) as the template and through synthetic conditions optimization, novel low-toxicity and environment-friendly ssDNA-functionalized room-temperature phosphorescent quantum dots (PS-T-ssDNA RTP QDs) were prepared at low temperature (37 °C). Then, the quantitative RTP-based mercury(II) (Hg2+) detection was achieved by utilizing the specific identifying ability of T-base-pair Hg2+ (T-Hg2+-T) and its photoinduced electron transfer. This RTP sensor in Hg2+ detection had a linear range of 0.02 to 0.8 µM and a detection limit of 4.8 nM. The dependence on RTP of QDs effectively avoids interference from background fluorescence and scattering light in the environment or biological samples. This sensor also possessed an RTP stability and a long service life and did not require sample pretreatment. Thus this sensor is suitable for environmental and quantitative Hg2+ detection in biological samples.

Wide temperature adaptive oxidase-like based on mesoporous manganese based metal-organic framework for detecting total antioxidant capacity.

Overcoming the intense variation of enzymatic activity among different temperatures is very critical in catalytic medicine and catalytic biology. Here, Mn-based metal-organic framework-based wide-temperature-adaptive mesoporous artificial enzymes (Mn-TMA-MOF) were designed and synthesized. The oxidase-like Mn-TMA-MOF showed excellent catalytic activity at 0-50 °C and avoided the activity loss and instability due to temperature variation that occurred. The excellent oxidase-like properties of Mn-TMA-MOF with wide temperature adaptativeness are mainly ascribed to the mixed oxidized state (Mn3+/Mn2+) and high substrate affinity (Km = 0.034 mM) of Mn. Moreover, the mesopore-micropores two-level structure of Mn-TMA-MOF provides a large space and surface area for enzyme catalysis. Based on the stability of Mn-TMA-MOF, we developed a colorimetric sensor that can detect total antioxidant capacity in fruits with a limit of detection up to 0.59 µM.

Gadolinium doped carbon dots for anti-gram-negative bacteria and visible light photodynamic enhancement of antibacterial effect.

Infection with gram-negative bacteria is the main source of the most serious infectious pathogens. Developing new antibacterial materials that break through their external membranes and stay in the bacterial body to result in an antibacterial effect is the key to achieving high efficiency against Gram-negative bacteria. A Gd-doped carbon dot (GRCD) was prepared using the approved therapeutic diagnostic agents Rose Bengal (RB) and gadolinium ions (Gd3+), which was used to resist Gram-negative bacteria (e.g. E. coli, Escherichia coli). GRCD not only showed strong antibacterial activity by destroying the external membranes of E. coli (inhibition rate against E. coli was 92.0 % at 20 µg/mL) but also bound to E. coli DNA and generated single oxygen (1O2) (quantum yield was 0.50) through visible light-driven catalysis, thus decomposing the DNA of E. coli and further enhancing the antibacterial performance of GRCD. Under visible light conditions, the inhibition rate against E. coli reached 95.8 % at a low concentration of 2.5 µg/mL, without obvious cytotoxicity to NIH3T3 cells. The use of GRCD in treating wound infections in mice caused by E. coli was quite good, without side reactions on the mice's essential organs. In this study, a new approach has been provided to the design and synthesis of carbon dot nanocomposites for use against Gram-negative bacteria.

Preparation of N-doped carbon dots and application to enhanced photosynthesis.

Regulation of photosynthesis rates is one of the key ways to increase crop yields. Carbon dots (CDs), which are low-toxity and biocompatible optical nanomaterials, can be easily prepared and are ideal for improving photosynthesis efficiency. In this study, nitrogen-doped CDs (CNDs) with a fluorescent quantum yield of 0.36 were synthesized via a one-step hydrothermal method. These CNDs can convert a part of ultraviolet light in solar energy to blue light (emission peak at 410 nm) that can be utilized in photosynthesis and that overlaps with the optical absorption spectrum of chloroplasts in the blue light zone. Consequently, chloroplasts can pick up photons excited by the CNDs and transfer them to the photosynthetic system in the form of electrons, thereby accelerating the photoelectron transport rate. These behaviors can reduce ultraviolet light stress on wheat seedlings and improve the efficiency of electron capture and transfer from chloroplasts through optical energy conversion. As a result, various photosynthetic indices and biomass of wheat seedlings are improved. Cytotoxicity experiments have showed that CNDs within a certain concentration range almost do not affect cell survival.

Preparation and Biotoxicity of Coal-Based Carbon Dot Nanomaterials.

Coal-based Carbon Dots (C-CDs) have gradually become a research focus due to the abundant raw materials and low preparation cost. Still, before coal-based carbon dots are widely used, a systematic biological toxicity study is the basis for the safe utilization of C-CDs. However, the level of toxicity and the mechanism of toxicity of C-CDs for organisms are still unclear. To ensure the safe utilization of C-CDs, the present study investigated C-CD nanomaterials as stressors to probe their biotoxic effects on plant, bacterial, and animal cells as well as the photocatalytic oxidative properties of C-CDs. The results showed that low concentrations of C-CDs could promote various growth indicators of wheat, and high concentrations of C-CDs had significant inhibitory effects on wheat growth; C-CDs had significant toxic effects on (S. aureus) at specific concentrations and were light-related; meanwhile, at concentrations of 1-5000 µg/mL, C-CDs were almost not toxic to HeLa cells; however, when irradiated at 365 nm, even low concentrations of C-CDs were toxic to cells by the mechanism that C-CDs could generate singlet oxygen (1O2) by photocatalytic oxidation under 365 nm excitation light, resulting in enhanced toxicity of C-CDs to cells.

The emerging role of long non-coding RNAs in schizophrenia.

Schizophrenia (SZ) is a severe psychiatric disorder which is contributed by both genetic and environmental factors. However, at present, its specific pathogenesis is still not very clear, and there is a lack of objective and reliable biomarkers. Accumulating evidence indicates that long non-coding RNAs (lncRNAs) are involved in the pathophysiology of several psychiatric disorders, including SZ, and hold promise as potential biomarkers and therapeutic targets for psychiatric disorders. In this review, we summarize and discuss the role of lncRNAs in the pathogenesis of SZ and their potential value as biomarkers and therapeutic targets.

Preparation and photodynamic antibacterial/anticancer effects of ultralong-lifetime room-temperature phosphorescent N-doped carbon dots.

Room-temperature phosphorescent (RTP) N-doped carbon-dots (CNDs) featuring eco-friendliness, low cost and high biocompatibility, are ideal photodynamic antibacterial and anticancer nanomaterials. However, the existing CNDs are limited by low singlet oxygen (1O2) quantum yield, which has become a bottleneck in the development of CNDs. One basic reason is the short T1-state exciton lifetime of CNDs. Herein, triethylenetetramine hexaacetic acid was used to synthesize CNDs via a one-step hydrothermal method. CNDs are characterized with low toxicity, high biocompatibility and ultralong-lifetime RTP (URTP). In addition to the URTP (average lifetime 414 ms) under solid conditions, CNDs even had URTP (average lifetime 320 ms) in a water environment. The ultralong T1 exciton lifetime largely extends the collision time between T1 state excitons and O2 and prolongs the energy transfer time, not only improving the quantum yield (0.63) of singlet oxygen (1O2) in solution, but also facilitating the photodynamic antibacterial and anticancer effects.

Synthesis of biological quantum dots based on single-strand DNA and its application in melamine detection.

By taking TC base-rich single-stranded DNA (ssDNA) as the raw material, a fluorescent biological quantum dots (Bio-dots) probe was prepared in one step through hydrothermal method, where its lifetime was greatly extended in comparison with Carbon quantum dots (CQDs), reaching 10.7 ns. The fluorescent detection of melamine in milk samples was realized by using the base pairing principle. Under the optimal conditions, the linear range of Bio-dots probe fluorescence sensor for melamine detection is 5-600 µM, and the detection limit is (3σ) 1.4 µM. Bio-dots can not only emit photoluminescence, but also detect target molecules as a functional recognition group. As the raw material ssDNA was basically non-toxic and there was no toxic substances participated in its synmanuscript process, this Bio-dots probe was a kind of green and environmentally-friendly photoluminescent functional material.

Fluorescence detection of fluorine ions in biological fluids based on aggregation-induced emission.

Traditional chemical and biological sensors developed through aggregation-induced emission (AIE) are mainly based on "Turning on" pattern of fluorescence enhancement, which often has poor selectivity and can be easily interfered with by other substances. On this basis, an AIE-based tetraphenyl ethylene (TPE) derivative (TPE-COOH) was prepared in this study and aggregated by adding Al3+, so as to form the TPE-COOH/Al3+ polymer. TPE-COOH fluorescence was enhanced through AIE principle, thus realizing the "Turning on" state. F- could bind to Al3+ after the addition of F- ions which would result in the decomposition of TPE-COOH/Al3+ aggregate, dissolved state of TPE-COOH and gradual reduction of fluorescence intensity of the system, thus realizing "Turning off" state. Moreover, F- ions in biological fluid were analyzed and detected through such AIE-based "Turning on-off" pattern. The linear range of this method for F- detection was 3-12 µM and the detection limit was 0.9 µM.

Preparation of galactose oxidase functional phosphorescent quantum dots and detection of D-galactose.

Environmental friendly nano biosensor can improve the detection performance of traditional biomolecular sensors and have important application value in practical applications. In this study, a kind of room temperature phosphorescence (RTP) quantum dots (QDs) (GOX RTP QDs) nanobiosensor was prepared by mineralization at room temperature (25 °C), using galactose oxidase (GOX) as template, which improved the catalytic ability of traditional GOx to D-Galactose. The specific enzyme substrate reaction between GOx and D-Galactose and photoinduced electron transfer (Piet) were used to detect the RTP of D-galactose. The linear range of D-galactose detection is 0.02-0.8 mM, and the detection limit of the method is 0.008 mM. This method is based on the RTP property of QDs, which can effectively avoid the interference of background fluorescence of biological samples, and does not need complex sample pretreatment process. Therefore, this method is more suitable for the quantitative detection of D-Galactose in biological samples.

-Phosphorescent Mesoporous Surface Imprinting Microspheres: Preparation and Application for Transferrin Recognition from Biological Fluids.

The relationship between the thickness of surface molecularly imprinted polymers (MIPs) and specific recognition performance of transferrin (Trf) as well as the quantitative relation between the grafting amount of Mn-ZnS room-temperature phosphorescence (RTP) quantum dots (QDs) (short for PQDs) and RTP signals for recognition of Trf was analyzed in this study. Based on analysis results, RTP protein mesoporous imprinting microspheres (SiO2-PQDs-MIPs) with high specificity and strong interference resistance were developed using a mesoporous SiO2 nanomaterial that can create more three-dimensional precise recognition sites as the matrix and using PQDs with strong resistance to background fluorescence interference as the luminescent materials. A discriminatory analysis of Trf was realized by the phosphorescence quenching principle based on light quenching caused by the photoinduced electron transfer. The concentration range, limit of detection, relative standard deviation, and imprinting factor of Trf detection under pH 7.4 are 0.05-1.0 µM, 0.014 µM, 3.23%, and 3.09, respectively. Although the sensing signals of SiO2-PQDs-MIPs for proteins are based on the phosphorescence of PQDs, they are particularly suitable for specific recognition and accurate quantitative detection of proteins in biological fluids. Research conclusions are expected to realize high-efficiency recognition of target proteins in actual biological samples.

"Turn on" room-temperature phosphorescent biosensors for detection of hyaluronic acid based on manganese-doped ZnS quantum dots.

Biosensors based on excellent optical properties of quantum dots (QDs) nanohybrids are efficient for biological detection. In this work, a room-temperature phosphorescent (RTP) PDAD-Mn-ZnS QDs biosensor was constructed with poly(diallyldimethylammonium chloride) (PDAD) as the modifier of MPA-capped Mn-ZnS QDs, and used to detect hyaluronic acid (HA). The newly-added HA induced severe electrostatic interaction with PDAD-Mn-ZnS QDs, leading to the aggregation between PDAD-Mn-ZnS QDs and HA and thereby enhancing RTP. The enhancement of RTP was proportional to the HA concentrations within certain ranges. On this basis, a high-performance HA sensor was built and this sensor had a detection limit of 0.03 µg mL-1 and a detection range of 0.08-2.8 µg mL-1. This proposed RTP sensor can avoid interferences from the background fluorescence or scattering light of the matrix that are encountered in spectrofluorometry. Thus, this biosensor is potentially suitable for detection of HA in real samples without complicated pretreatment.

Hybrid detection of target sequence DNA based on phosphorescence resonance energy transfer.

The severe background fluorescence and scattering light of real biological samples or environmental samples largely reduce the sensitivity and accuracy of fluorescence resonance energy transfer sensors based on fluorescent quantum dots (QDs). To solve this problem, we designed a novel target sequence DNA biosensor based on phosphorescent resonance energy transfer (PRET). This sensor relied on Mn-doped ZnS (Mn-ZnS) room-temperature phosphorescence (RTP) QDs/poly-(diallyldimethylammonium chloride) (PDADMAC) nanocomposite (QDs+) as the energy donor and the single-strand DNA-ROX as the energy receptor. Thereby, an RTP biosensor was built and used to quantitatively detect target sequence DNA. This biosensor had a detection limit of 0.16nM and a linear range of 0.5-20nM for target sequence DNA. The dependence on RTP of QDs effectively avoided the interference from background fluorescence and scattering light in biological samples. Moreover, this sensor did not need sample pretreatment. Thus, this sensor compared with FRET is more feasible for quantitative detection of target sequence DNA in biological samples. Interestingly, the QDs+ nanocomposite prolonged the phosphorescence lifetime of Mn-ZnS QDs by 2.6 times to 4.94ms, which was 5-6 magnitude-order larger than that of fluorescent QDs. Thus, this sensor largely improves the optical properties of QDs and permits chemical reactions at a long enough time scale.

A DNA probe based on phosphorescent resonance energy transfer for detection of transgenic 35S promoter DNA.

A QDs-DNA nano-probe was made by combining Mn-doped ZnS room-temperature phosphorescence (RTP) quantum dots (QDs) and DNA. Then an RTP sensor for quantitative detection of genetically-modified mark sequence cauliflower mosaic virus 35S promoter (Ca MV 35S) DNA was built on basis of phosphorescent resonance energy transfer (PRET). The underlying principles were that a QDs-DNA water-soluble nano-probe was built by connecting single-strand DNA to the surfaces of QDs via a ligand exchange method. This probe had good RTP performance and could well identify Ca MV 35S. Thereby, the simple, rapid and efficient detection of genetically-modified organisms was realized. With the increase of target DNA sequence, the phosphorescent intensity of QDs was gradually reduced due to the energy transfer between QDs and the organic quencher BHQ2. This sensor had a detection limit of 4.03nM and a detection range of 12-300nM. Moreover, this sensor had high selectivity. This sensor could effectively detect the target DNA compared with mismatched and random sequences. Thus, this method is very promising for biological analysis.

Improving the Thermostability of Acidic Pullulanase from Bacillus naganoensis by Rational Design.

Pullulanase (EC 3.2.1.41) plays an important role in the specific hydrolysis of branch points in amylopectin. Enhancing its thermostability is required for its industrial application. In this study, rational protein design was used to improve the thermostability of PulB from Bacillus naganoensis (AB231790.1), which has strong enzymatic properties. Three positive single-site mutants (PulB-D328H, PulB-N387D, and PulB-A414P) were selected from six mutants. After incubation at 65°C for 5 min, the residual activities of PulB-D328H, PulB-N387D, and PulB-A414P were 4.5-, 1.7-, and 1.47-fold higher than PulB-WT, and their Tm values (the temperature at which half protein molecule denature) were 1.8°C, 0.4°C, and 0.9°C higher than PulB-WT, respectively. Then the final combined mutant PulB-328/387/414 was constructed. The t1/2 of it was 12.9-fold longer than that of PulB-WT at 65°C and the total increase in Tm of it (5.0°C) was almost 60% greater than the sum of individual increases (3.1°C). In addition, kinetic studies revealed that the kcat and the kcat/Km of PulB-328/387/414 increased by 38.8% and 12.9%. The remarkable improvement in thermostability and the high catalytic efficiency of PulB-328/387/414 make it suitable for industrial applications.