Dysfunction of duplicated pair rice histone acetyltransferases causes segregation distortion and an interspecific reproductive barrier.

Postzygotic reproductive isolation, which results in the irreversible divergence of species, is commonly accompanied by hybrid sterility, necrosis/weakness, or lethality in the F1 or other offspring generations. Here we show that the loss of function of HWS1 and HWS2, a couple of duplicated paralogs, together confer complete interspecific incompatibility between Asian and African rice. Both of these non-Mendelian determinants encode the putative Esa1-associated factor 6 (EAF6) protein, which functions as a characteristic subunit of the histone H4 acetyltransferase complex regulating transcriptional activation via genome-wide histone modification. The proliferating tapetum and inappropriate polar nuclei arrangement cause defective pollen and seeds in F2 hybrid offspring due to the recombinant HWS1/2-mediated misregulation of vitamin (biotin and thiamine) metabolism and lipid synthesis. Evolutionary analysis of HWS1/2 suggests that this gene pair has undergone incomplete lineage sorting (ILS) and multiple gene duplication events during speciation. Our findings have not only uncovered a pair of speciation genes that control hybrid breakdown but also illustrate a passive mechanism that could be scaled up and used in the guidance and optimization of hybrid breeding applications for distant hybridization.

Optimization of rice panicle architecture by specifically suppressing ligand-receptor pairs.

Rice panicle architecture determines the grain number per panicle and therefore impacts grain yield. The OsER1-OsMKKK10-OsMKK4-OsMPK6 pathway shapes panicle architecture by regulating cytokinin metabolism. However, the specific upstream ligands perceived by the OsER1 receptor are unknown. Here, we report that the EPIDERMAL PATTERNING FACTOR (EPF)/EPF-LIKE (EPFL) small secreted peptide family members OsEPFL6, OsEPFL7, OsEPFL8, and OsEPFL9 synergistically contribute to rice panicle morphogenesis by recognizing the OsER1 receptor and activating the mitogen-activated protein kinase cascade. Notably, OsEPFL6, OsEPFL7, OsEPFL8, and OsEPFL9 negatively regulate spikelet number per panicle, but OsEPFL8 also controls rice spikelet fertility. A osepfl6 osepfl7 osepfl9 triple mutant had significantly enhanced grain yield without affecting spikelet fertility, suggesting that specifically suppressing the OsEPFL6-OsER1, OsEPFL7-OsER1, and OsEPFL9-OsER1 ligand-receptor pairs can optimize rice panicle architecture. These findings provide a framework for fundamental understanding of the role of ligand-receptor signaling in rice panicle development and demonstrate a potential method to overcome the trade-off between spikelet number and fertility.

An α/ß hydrolase family member negatively regulates salt tolerance but promotes flowering through three distinct functions in rice.

Ongoing soil salinization drastically threatens crop growth, development, and yield worldwide. It is therefore crucial that we improve salt tolerance in rice by exploiting natural genetic variation. However, many salt-responsive genes confer undesirable phenotypes and therefore cannot be effectively applied to practical agricultural production. In this study, we identified a quantitative trait locus for salt tolerance from the African rice species Oryza glaberrima and named it as Salt Tolerance and Heading Date 1 (STH1). We found that STH1 regulates fatty acid metabolic homeostasis, probably by catalyzing the hydrolytic degradation of fatty acids, which contributes to salt tolerance. Meanwhile, we demonstrated that STH1 forms a protein complex with D3 and a vital regulatory factor in salt tolerance, OsHAL3, to regulate the protein abundance of OsHAL3 via the 26S proteasome pathway. Furthermore, we revealed that STH1 also serves as a co-activator with the floral integrator gene Heading date 1 to balance the expression of the florigen gene Heading date 3a under different circumstances, thus coordinating the regulation of salt tolerance and heading date. Notably, the allele of STH1 associated with enhanced salt tolerance and high yield is found in some African rice accessions but barely in Asian cultivars. Introgression of the STH1HP46 allele from African rice into modern rice cultivars is a desirable approach for boosting grain yield under salt stress. Collectively, our discoveries not only provide conceptual advances on the mechanisms of salt tolerance and synergetic regulation between salt tolerance and flowering time but also offer potential strategies to overcome the challenges resulted from increasingly serious soil salinization that many crops are facing.

A genetic module at one locus in rice protects chloroplasts to enhance thermotolerance.

How the plasma membrane senses external heat-stress signals to communicate with chloroplasts to orchestrate thermotolerance remains elusive. We identified a quantitative trait locus, Thermo-tolerance 3 (TT3), consisting of two genes, TT3.1 and TT3.2, that interact together to enhance rice thermotolerance and reduce grain-yield losses caused by heat stress. Upon heat stress, plasma membrane-localized E3 ligase TT3.1 translocates to the endosomes, on which TT3.1 ubiquitinates chloroplast precursor protein TT3.2 for vacuolar degradation, implying that TT3.1 might serve as a potential thermosensor. Lesser accumulated, mature TT3.2 proteins in chloroplasts are essential for protecting thylakoids from heat stress. Our findings not only reveal a TT3.1-TT3.2 genetic module at one locus that transduces heat signals from plasma membrane to chloroplasts but also provide the strategy for breeding highly thermotolerant crops.

A rice QTL GS3.1 regulates grain size through metabolic-flux distribution between flavonoid and lignin metabolons without affecting stress tolerance.

Grain size is a key component trait of grain weight and yield. Numbers of quantitative trait loci (QTLs) have been identified in various bioprocesses, but there is still little known about how metabolism-related QTLs influence grain size and yield. The current study report GS3.1, a QTL that regulates rice grain size via metabolic flux allocation between two branches of phenylpropanoid metabolism. GS3.1 encodes a MATE (multidrug and toxic compounds extrusion) transporter that regulates grain size by directing the transport of p-coumaric acid from the p-coumaric acid biosynthetic metabolon to the flavonoid biosynthetic metabolon. A natural allele of GS3.1 was identified from an African rice with enlarged grains, reduced flavonoid content and increased lignin content in the panicles. Notably, the natural allele of GS3.1 caused no alterations in other tissues and did not affect stress tolerance, revealing an ideal candidate for breeding efforts. This study uncovers insights into the regulation of grain size though metabolic-flux distribution. In this way, it supports a strategy of enhancing crop yield without introducing deleterious side effects on stress tolerance mechanisms.

UDP-glucosyltransferase regulates grain size and abiotic stress tolerance associated with metabolic flux redirection in rice.

Grain size is an important component trait of grain yield, which is frequently threatened by abiotic stress. However, little is known about how grain yield and abiotic stress tolerance are regulated. Here, we characterize GSA1, a quantitative trait locus (QTL) regulating grain size and abiotic stress tolerance associated with metabolic flux redirection. GSA1 encodes a UDP-glucosyltransferase, which exhibits glucosyltransferase activity toward flavonoids and monolignols. GSA1 regulates grain size by modulating cell proliferation and expansion, which are regulated by flavonoid-mediated auxin levels and related gene expression. GSA1 is required for the redirection of metabolic flux from lignin biosynthesis to flavonoid biosynthesis under abiotic stress and the accumulation of flavonoid glycosides, which protect rice against abiotic stress. GSA1 overexpression results in larger grains and enhanced abiotic stress tolerance. Our findings provide insights into the regulation of grain size and abiotic stress tolerance associated with metabolic flux redirection and a potential means to improve crops.

Latest Research Advance of Myeloproliferative Diseases Related Genes-Review / 中国实验血液学杂志

JAK2, MPL and CALR gene mutations play an important role in the onset of myeloproliferative disease(MPD). The latest researches show that the difference of ATP binding ability between the wild type JAK2 protein and mutated JAK2 protein can help us understand the pathogenesis of the MPD further, and the clinical manifestation is related to the mutation burden of the JAK2. In some ET and PMF patients, research find the expression of MPL mutation, which can affects the progress of the disease by collaborating with the JAK2 mutation. CALR mutation is a gene related with the MPD that has been found recently. The pathogenesis of the CALR is similar to that of the JAK2, while there are some features in clinical manifestation comparing with the other mutations.

The cytotoxicity of methacryloxylethyl cetyl ammonium chloride, a cationic antibacterial monomer, is related to oxidative stress and the intrinsic mitochondrial apoptotic pathway

Antibacterial monomers incorporated in dentin bonding systems may have toxic effects on the pulp. Thus, the cytotoxicity of antibacterial monomers and its underlying mechanisms must be elucidated to improve the safety of antibacterial monomer application. The influence of an antibacterial monomer, methacryloxylethyl cetyl ammonium chloride (DMAE-CB), on the vitality of L929 mouse fibroblasts was tested using MTT assay. Cell cycle progression was studied using flow cytometry. Production of intracellular reactive oxygen species (ROS) after DMAE-CB treatment was measured using 2,7-dichlorodihydrofluorescein diacetate staining and flow cytometry analysis. Loss of mitochondrial membrane potential, disturbance of Bcl-2 and Bax expression, as well as release of cytochrome C were also measured using flow cytometry analysis or Western blot to explore the possible involvement of the mitochondrial-related apoptotic pathway. DMAE-CB elicited cell death in a dose-dependent manner and more than 50 percent of cells were killed after treatment with 30 µM of the monomer. Both necrosis and apoptosis were observed. DMAE-CB also induced G1- and G2-phase arrest. Increased levels of intracellular ROS were observed after 1 h and this overproduction was further enhanced by 6-h treatment with the monomer. DMAE-CB may cause apoptosis by disturbing the expression of Bcl-2 and Bax, reducing the mitochondrial potential and inducing release of cytochrome C. Taken together, these findings suggest that the toxicity of the antibacterial monomer DMAE-CB is associated with ROS production, mitochondrial dysfunction, cell cycle disturbance, and cell apoptosis/necrosis.

Effects of acid etching time on the degradation of type I collagen in dentin / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of acid etching time on the degradation of type Icollagen in dentin.</p><p><b>METHODS</b>Dentin was conditioned with 37% phosphoric acid for 10, 15, 30 and 60 s. There was no treatment for the control group. Quantity of collagen degradation in each group was determined by enzyme linked immunosorbent assay. Observations were carried out by means of a field emission in-lens scanning electron microscope (FEISEM).</p><p><b>RESULTS</b>Samples conditioned with 37% phosphoric acid for 60 s showed the most degradation of collagen, which was 4.86 (1.55) mg/g, followed by 30 s group and 15 s group, which were 2.76 (0.87) mg/g and 1.93 (0.88) mg/g, respectively. Group of 10 s was 0.95 (0.38) mg/g. The control group showed the least degradation of 0.06 (0.03) mg/g. Significant differences in collagen degradation were found among groups (P < 0.005). Smear layer were removed well but tubular orifices and collagen fibrils were covered by particles after dentin being etched with 37% phosphoric acid for 10 s, while open and clear tubular orifices were observed for 15 s group. Smoother surfaces of exposed collagen fibrils and fewer globular particles were found in 30 s group than in 15 s group. In the 60 s group, the number of major fibrils decreased while minor branching fibrils increased, which indicate that the intratubular structure collapsed and fibrils fractured.</p><p><b>CONCLUSIONS</b>Dentin conditioned with 37% phosphoric acid for 15 s can result in mineral dissolution without collagen structure damage. However, longer applications of 37% phosphoric acid within 60 s may increase collagen degradation.</p>

Influence of nano-silica content on flexural properties of the aluminum borate whisker and silica filler composite resins / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To discuss the influence of nano-silica content which was hydrolyzed by tetraethyl orthosioate (TEOS) on the aluminum borate whisker (AlBw) and silica filler composite resins on flexural properties.</p><p><b>METHODS</b>The nanometer-size silicon dioxide (SiO2) particles were prepared by sol-gel method based on tetraethyl orthosioate. Different proportion of AlBw and SiO2 were fused and attached onto the surface of AlBw through high temperature, then polymerized with resin matrix after surface siliconization and their flexural strength and flexural modulus were determined. The effects of heat treatment to the surface morphology of AlBw and the shapes of the mixture at various proportions were characterized by TEM.</p><p><b>RESULTS</b>The flexural properties of dental composite resins with AlBw-SiO2 compound as inorganic fillers were significantly improved. The flexural property of a new type of dental composite resins was(130.29 +/- 8.38) MPa, when the mass ratio of AlBw and nano-SiO2 particle was 3:1.</p><p><b>CONCLUSION</b>Nano-silica content which was hydrolyzed by tetraethyl orthosioate improved flexural properties of the aluminum borate whisker and silica filler composite resins.</p>

Antibacterial effects of a dental adhesive incorporating a quaternary ammonium monomer against Streptococcus mutans / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To incorporate an antibacterial monomer, methacryloxylethyl cetyl dimethyl ammonium chloride(DMAE-CB), into a dental adhesive, and to evaluate the antibacterial activity against Streptococcus mutans (Sm) of this DMAE-CB-incorporated adhesive after being cured.</p><p><b>METHODS</b>DMAE-CB was incorporated into a dimethacrylates-based dental adhesive as experimental group. The adhesive without DMAE-CB served as a negative control. Thirty-nine specimens were fabricated for each group. The effects of the cured adhesives on the growth and adherence of Sm were evaluated with growth inhibition assay and spectrophotometry respectively. The influence of aging treatment and saliva treatment on the antibacterial efficiency of the modified adhesive was evaluated. Moreover, the bacterial growth of Sm in the eluents of two different adhesives was examined.</p><p><b>RESULTS</b>Compared with negative control, the cured DMAE-CB-incorporated dental adhesive exhibited inhibitory effect on the growth and adherence of Sm. The inhibition rate was 99% and the absorbance value was (0.332 +/- 0.063) for experimental group, significantly lower than that of negative control (0.434 +/- 0.093, P = 0.021). Moreover, after aging treatment the DMAE-CB-incorporated adhesive could still inhibit the growth and adherence of Sm; the inhibition rate was 99%, and the absorbance value of experimental group was (0.372 +/- 0.062), significantly lower than that of negative control (0.455 +/- 0.066, P = 0.022). After saliva treatment the DMAE-CB-incorporated adhesive could still inhibit the growth and adherence of Sm; the inhibition rate was 90%, and the absorbance value of experimental group was (0.299 +/- 0.061), significantly lower than that of negative control (0.370 +/- 0.068, P = 0.045). However, the eluent of DMAE-CB-incorporated adhesive didn't show inhibitory effect on the growth of Sm when compared with negative control, and the antibacterial effect and the doubling time of experimental group [(130.5 +/- 8.4) min] had no statistical difference than negative control [(126.4 +/- 7.0) min, P = 0.298].</p><p><b>CONCLUSIONS</b>The incorporation of DMAE-CB can render the dental adhesive with antibacterial activity after polymerization via influencing the growth and adherence of Sm.</p>

Preparation and antibacterial activity of quaternary ammonium salt monomers / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To prepare three quaternary ammonium salt (QAS) monomers, and to compare their antibacterial activities against four oral bacterial strains.</p><p><b>METHODS</b>Three antibacterial monomers [methacryloxyethyl benzyl dimethyl ammonium chloride (DMAE-BC), methacryloxyethyl m-chloro benzyl dimethyl ammonium chloride (DMAE-m-CBC), methacryloxyethyl cetyl dimethyl ammonium chloride (DMAE-CB)] were synthesized according to the general structure of target monomers. Their antibacterial effects were investigated using the broth dilution test on Gram-positive and Gram-negative bacterial strains (Streptococcus mutans, Streptococcus sanguis, Porphyromonas gingivalis, Prevotella melaninogenica ).</p><p><b>RESULTS</b>Three different monomers were successfully obtained. All the tested bacterial strains were susceptible to the three monomers, among which DMAE-CB exhibited the lowest minimal inhibitory concentrations (MIC) ranging from 1.2 to 4.8 mg/L.</p><p><b>CONCLUSIONS</b>All these three QAS monomers have different antibacterial activities against four oral bacteria strains. The data indicate that DMAE-CB may be a candidate antibacterial agent for oral infectious diseases.</p>

Cathodic electrochemiluminescence of acetonitrile, acetonitrile-1,10-phenanthroline and acetonitrile-ternary Eu(III) complexes at a gold electrode.

Cathodic electrochemiluminescence (ECL) behaviours of the acetonitrile, acetonitrile-1,10-phenanthroline (phen) and acetonitrile-ternary Eu(III) complex systems at a gold electrode were studied. One very weak cathodic ECL-2 at -3.5 V was observed in 0.1 mol/L tetrabutylammonium tetrafluoroborate (TBABF(4)) acetonitrile solution. When 10 mmol/L tetrabutylammonium peroxydisulphate [(TBA)(2)S(2)O(8)] was added to 0.1 mol/L TBABF(4) acetonitrile solution, another cathodic ECL-1 at -2.7 V appeared and the potential for ECL-2 was shifted from -3.5 to -3.1 V. Furthermore, ECL-2 intensity was enhanced about 20-fold. When 1 x 10(-4) mol/L phen was added to 0.1 mol/L TBABF(4) + 10 mmol/L (TBA)(2)S(2)O(8) acetonitrile solution, the ECL intensities of ECL-1 and ECL-2 were enhanced about 20-fold compared with those of 0.1 mol/L TBABF(4) + 10 mmol/L (TBA)(2)S(2)O(8) acetonitrile solution. The maximum emission peaks of ECL-1 and ECL-2 in the three systems mentioned above appeared at about 530 nm. The products obtained by electrolysing 0.1 mol/L TBABF(4) acetonitrile solution at -3.5 V for 20 min were analysed by Fourier Transform Infrared (FTIR) spectra and gas chromatography-mass spectrometry (GC-MS) and the emitter of ECL-1 and ECL-2 was identified as excited state polyacetonitrile. When ternary Eu(III) complexes were presented in 0.1 mol/L TBABF(4) + 10 mmol/L (TBA)(2)S(2)O(8) acetonitrile solution, another maximum emission peak with a narrow band centred at about 610 nm appeared in ECL-1 in addition to the maximum emission peaks at about 530 nm for ECL-1 and ECL-2. The emitter of ECL emission at 610 nm was identified as the excited states Eu(III)*. The mechanisms for cathodic ECL behaviours of the acetonitrile, acetonitrile-phen and acetonitrile-ternary Eu(III) complex systems at a gold electrode have been proposed. The extremely sharp emission bands for ternary Eu(III) complexes may have analytical potential.

Multi-channel electrochemiluminescence of luminol at a copper electrode.

Multi-channel electrochemiluminescence (ECL) of luminol at a copper electrode has been studied under conventional cyclic voltammetric (CV) conditions. Compared with the ECL of luminol at other electrodes, three ECL peaks were observed at 0.30, -0.24 and -0.65 V (vs. SCE), respectively, which was also imaged by a CCD camera. The effects of potential scan direction, anodic reverse potential, the presence of N2 and O2 of the solution, the pH of the solution, the NaNO3 concentration and the potential scan rate were examined. The effect of n-alkanethiol self-assembled monolayers on copper electrodes and 20 L-amino acids, dopamine, adrenaline and noradrenaline on the ECL of luminol were also investigated. The emission spectra of various ECL peaks at different potentials demonstrated that all ECL peaks were related to the luminol reaction. The results show that the oxygen dissolved in solution and copper oxide covered on the surface of the electrode play an important role in the luminol ECL process at a copper electrode. It has been proposed that three ECL channels of luminol at a copper electrode resulted from the reactions of luminol or luminol radical electrooxidized by luminol with various electrogenerated oxygen-containing species, such as O2, OOH- and copper oxides at different potentials.