[Effects of Straw Returning and Biochar Addition on Greenhouse Gas Emissions from High Nitrate Nitrogen Soil After Flooding in Rice-vegetable Rotation System in Tropical China].

In rice-vegetable rotation systems in tropical areas, a large amount of nitrate nitrogen accumulates after fertilization in the melon and vegetable season, which leads to the leaching of nitrate nitrogen and a large amount of N2O emission after the seasonal flooding of rice, which leads to nitrogen loss and intensification of the greenhouse effect. How to improve the utilization rate of nitrate nitrogen and reduce N2O emissions has become an urgent problem to be solved. Six treatments were set up [200 mg·kg-1 KNO3 (CK); 200 mg·kg-1 KNO3 + 2% biochar addition (B); 200 mg·kg-1 KNO3+1% peanut straw addition (P); 200 mg·kg-1 KNO3 + 2% biochar + 1% peanut straw addition (P+B); 200 mg·kg-1 KNO3 + 1% rice straw addition (R); 200 mg·kg-1 KNO3 + 2% biochar+1% rice straw addition (R+B)] and cultured at 25℃ for 114 d to explore the effects of organic material addition on greenhouse gas emissions and nitrogen use after flooding in high nitrate nitrogen soil. The results showed that compared with that in CK, adding straw or combining straw with biochar significantly increased soil pH (P<0.05). The B and P treatments significantly increased the cumulative N2O emissions by 41.6% and 28.5% (P<0.05), and the P+B, R, and R+B treatments significantly decreased the cumulative N2O emissions by 14.1%, 24.7%, and 36.7% (P<0.05), respectively. The addition of straw increased the net warming potential of greenhouse gases (NGWP). The addition of coir biochar significantly reduced the effect of straw on NGWP (P<0.05). The combined application of straw and biochar decreased NGWP, and P+B significantly decreased NGWP, but that with R+B was not significant (P>0.05). Adding straw or biochar significantly increased soil microbial biomass carbon (MBC) (P<0.05), and that of P+B was the highest (502.26 mg·kg-1). The combined application of straw and biochar increased soil microbial biomass nitrogen (MBN), and that of P+B was the highest. The N2O emission flux was negatively correlated with pH (P<0.01) and positively correlated with NH4+-N and NO3--N (P<0.01). The cumulative emission of N2O was negatively correlated with MBN (P<0.05). There was a significant negative correlation between NO3--N and MBN (P<0.01), indicating that the reduction in NO3--N was likely to be held by microorganisms, and the increase in the microbial hold of NO3--N also reduced N2O emission. In conclusion, the combined application of peanut straw and coconut shell biochar could significantly inhibit N2O emission and increase soil MBC and MBN, which is a reasonable measure to make full use of nitrogen fertilizer, reduce nitrogen loss, and slow down N2O emission after the season of Hainan vegetables.

Editing the cystine knot motif of MSTN enhances muscle development of Liang Guang Small Spotted pigs.

Myostatin (MSTN) is a member of the transforming growth factor-ß (TGF-ß) family, and functions as an inhibitor of muscle growth. Disrupting the inhibitory effect of MSTN on growth can provide an effective way to increase the muscle yield of livestock and poultry. The cysteine knot motif of TGF-ß can stabilize the structure of MSTN protein and plays an important regulatory role in the biological function of MSTN. Accordingly, in this study, we used the CRISRP/Cas9 to edit the exon 3 of MSTN in the kidney cells of Liang Guang Small Spotted pig (LPKCs), in order to disrupt the cysteine knot motif of MSTN and remove the inhibitory effect of MSTN on its target genes.MSTN-edited LPKCs were obtained through fluorescence-activated cell sorting (FACS) and used as donor cells for somatic cell nuclear transfer (SCNT) to generate cloned embryos, which were then transferred to surrogate sows to finally obtain eight MSTN-edited Liang Guang Small Spotted piglets. Among them, two survived to 10 days old. Genotyping revealed that these two piglets were gene edited heterozygotes with base deletion and substitution occurred within the coding sequence of C106 and C108 at the cystine knot motif of MSTN. These changes resulted in frameshift mutations, and conversion of C106 and C108 to other amino acids. More developments of muscles were observed at the shoulders and hips of the heterozygotes of MSTN-edited Liang Guang Small Spotted pigs. H&E analysis showed that the cross-sectional area (CSA) of myofiber inMSTN-edited pigs was significantly decreased, and the number of myofiber were significantly increased. Western blot analysis showed that the disruption of C106 and C108 did not affect the expression of MSTN protein, but significantly up-regulated the expression of its target genes such as Myf5, MyoD, Myogenin and other myogenic regulatory factors. In summary, the gene-edited pig model obtained in this study did not cause complete loss of MSTN expression, and could retain other biological functions of MSTN, thereby promoting muscle growth while minimizing the potential adverse effects on complete loss of MSTN in the Liang Guang Small Spotted pigs.

Bone repair scaffold coated with bone morphogenetic protein-2 for bone regeneration in murine calvarial defect model: Systematic review and quality evaluation.

To systematically assess the effects of hydroxyapatite bone repair scaffold coated with bone morphogenetic protein-2 on murine calvarial defect models and to determine the quality of studies according to the Animal Research Reporting in In Vivo Experiments guidelines. Internet search was performed in duplicate using PubMed, MEDLINE, Ovid and Embase databases (without restrictions on publication date). The Animal Research Reporting in In Vivo Experiments guidelines were used to evaluate the quality of selected studies. Following screening, 12 studies were eligible for the review. Studies with average quality coefficients predominated (66.67%), followed by poor (25%) and excellent (8.33%) quality coefficients. Minimum quality scores were assigned to the Animal Research Reporting in In Vivo Experiments guideline items: housing and husbandry (9), allocation (11), outcomes (12), interpretation (18) and generalizability (19). Sprague-Dawley rats were the most frequently used (50%) species, and most studies had a sample size of more than 30 (58.33%). A defect dimension of 5 mm was the most common (33.33%). The biological hydroxyapatite composite scaffold was common (50%), and the bioactive factors were bone morphogenetic protein-2 (50%) and recombinant human bone morphogenetic protein-2 (50%). Histomorphometric results showed that bone morphogenetic protein-2 enhanced the capacity to regenerate bone considerably. In addition, scaffolds with bone morphogenetic protein-2 resulted in a significant increase in the blood vessel in the new bone. The findings suggested that data on animal experiments of hydroxyapatite scaffold coated with bone morphogenetic protein-2 in murine calvarial defect models lack homogeneity. Animal experiment should follow the Animal Research Reporting in In Vivo Experiments guidelines to promote the high quality, integrity and reproducibility. This systematic review suggested that bone morphogenetic protein-2 enhanced the capacity to regenerate bone and the angiogenesis in the new bone.

Scaffolds for the repair of bone defects in clinical studies: a systematic review.

BACKGROUND: This systematic review aims to summarize the clinical studies on the use of scaffolds in the repair of bony defects. METHODS: The relevant articles were searched through PubMed database. The following keywords and search terms were used: "scaffolds," "patient," "clinic," "bone repair," "bone regeneration," "repairing bone defect," "repair of bone," "osteanagenesis," "osteanaphysis," and "osteoanagenesis." The articles were screened according to inclusion and exclusion criteria, performed by two reviewers. RESULTS: A total of 373 articles were obtained using PubMed database. After screening, 20 articles were identified as relevant for the purpose of this systematic review. We collected the data of biological scaffolds and synthetic scaffolds. There are eight clinical studies of biological scaffolds included collagen, gelatin, and cellular scaffolds for bone healing. In addition, 12 clinical studies of synthetic scaffolds on HAp, TCP, bonelike, and their complex scaffolds for repairing bone defects were involved in this systematic review. CONCLUSIONS: There are a lot of clinical evidences showed that application of scaffolds had a good ability to facilitate bone repair and osteogenesis. However, the ideal and reliable guidelines are insufficiently applied and the number and quality of studies in this field remain to be improved.

Functional characterization of the promoter of carbonyl reductase 1 gene in porcine endometrial cells.

Prostaglandins (PGs) play a critical role in porcine reproduction, of which prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α) exert antiluteolytic and luteolysis actions, respectively. As a rate-limiting enzyme, carbonyl reductase 1 (CBR1) catalyzes the conversion of PGE2 to PGF2α. A high ratio of PGE2:PGF2α is beneficial to the establishment and maintenance of porcine pregnancy. PG is essential for the establishment of pregnancy which resembles the proinflammatory response and nuclear factor κB (NF-κB) is involved in the process. Bioinformatic analysis has shown that NF-κB is a possible factor bound to two cis-regulatory elements in CBR1 promoter. In this study, we cloned the 2997 bp (-2875/+122) of the promoter, and constructed six 5'-deleted dual-luciferase reporter recombinant vectors. In endometrial cells, the region of P2 (-1640/+7) exhibited the greatest transcriptional activity at driving luciferase expression, but not significantly different from that of P1 (-2089/+7). The activity of P1, P2, and P3 (-1019/+7) was highly significantly higher than that of others (P<0.01), suggesting that two positive regulatory elements were likely present in the regions of -1640/-1019 and -1019/-647. The results also showed that the -1640/-647 region was indispensable for the promoter. The results of chromatin immunoprecipitation (ChIP) demonstrated that the NF-κB subunit p65 binds to one site around -1545/-1531. Using four reference genes, we found that the over-expression of p65 enhanced the expression of CBR1 (P<0.05) in porcine endometrial epithelial cells, while knockdown of the p65 did not down-regulate the CBR1 expression. These results indicated that NF-κB (p65) could bind to the special element of CBR1 gene promoter in porcine endometrial epithelial cells in vitro. The binding site of NF-κB was a positive regulator for the CBR1 gene promoter, but was not necessary for the basic expression.

Three-photon-induced blue emission with narrow bandwidth from hot flower-like ZnO nanorods.

ZnO nanorods (NRs) self-organized into flowers were synthesized at different temperatures ranging from 100°C to 180°C by using the hydrothermal method. The existence of Zn interstitials (Zn(i)) was confirmed by X-ray photoelectron spectroscopy and a larger amount of Zn(i) was found in the ZnO NRs prepared at higher temperatures. A redshift of the emission peak of more than 15 nm was observed for the ZnO NRs under single photon excitation. The nonlinear optical properties of the flower-like ZnO NRs were characterized by using focused femtosecond laser light and strong three-photon-induced luminescence was observed at an excitation wavelength of ~750 nm. More interestingly, a large redshift of the emission peak was observed with increasing excitation intensity, resulting in efficient blue emission with a narrow bandwidth of ~30 nm. It was confirmed that the large redshift originates from the heating of the ZnO NRs to a temperature of more than 800°C and the closely packed ZnO NRs in the flowers play a crucial role in heat accumulation. The stable and efficient three-photon-induced blue emission from such ZnO NRs may find potential applications in the fields of optical display, high-temperature sensors and light therapy of tumors.

Hollow hydroxyapatite microspheres/chitosan composite as a sustained delivery vehicle for rhBMP-2 in the treatment of bone defects.

Composite scaffold comprised of hollow hydroxyapatite (HA) and chitosan (designated hHA/CS) was prepared as a delivery vehicle for recombinating human bone morphogenetic protein-2 (rhBMP-2). The in vitro and in vivo biological activities of rhBMP2 released from the composite scaffold were then investigated. The rhBMP-2 was firstly loaded into the hollow HA microspheres, and then the rhBMP2-loaded HA microspheres were further incorporated into the chitosan matrix. The chitosan not only served to bind the HA microspheres together and kept them at the implant site, but also effectively modified the release behavior of rhBMP-2. The in vitro release and bioactivity analysis confirmed that the rhBMP2 could be loaded and released from the composite scaffolds in bioactive form. In addition, the composite scaffolds significantly reduced the initial burst release of rhBMP2, and thus providing prolonged period of time (as long as 60 days) compared with CS scaffolds. In vivo bone regenerative potential of the rhBMP2-loaded composite scaffolds was evaluated in a rabbit radius defect model. The results revealed that the rate of new bone formation in the rhBMP2-loaded hHA/CS group was higher than that in both negative control and rhBMP2-loaded CS group. These observations suggest that the hHA/CS composite scaffold would be effective and feasible as a delivery vehicle for growth factors in bone regeneration and repair.

Efficient blue light emission from In0.16Ga0.84N/GaN multiple quantum wells excited by 2.48-µm femtosecond laser pulses.

We report on the efficient blue light emission from In0.16Ga0.84N/GaN multiple quantum wells excited by femtosecond laser pulses with long wavelengths ranging from 1.24 to 2.48 µm. It is found that the trap states in GaN barrier layers lead to an efficient cascade multiphoton absorption in which the carriers are generated through simultaneous absorption of n (n=1 and 2) photons to the trap states, followed by simultaneous absorption of m (m=3, 4, and 5) photons to the conduction band. The dependence of the upconversion luminescence on excitation intensity exhibits a slope between n and n+m, which is in good agreement with the prediction based on the rate equation model.

Controllable color display induced by excitation-intensity-dependent competition between second and third harmonic generation in ZnO nanorods.

We investigated the second and third harmonic generation (SHG and THG) in ZnO nanorods (NRs) by using a femtosecond laser (optical parametric amplifier with tunable wavelengths) with a long excitation wavelength of 1350 nm and a low repetition rate of 1 kHz. The damage threshold for ZnO NRs in this case was sufficiently large, enabling us to observe the competition between SHG and THG. The transition from red to blue emission and the mixing of red and blue light with different ratios were successfully demonstrated by simply varying excitation intensity, implying the potential applications of ZnO NRs in all-optical display.

A specific and rapid colorimetric method to monitor the activity of methionine sulfoxide reductase A.

Considerable evidence indicates that methionine sulfoxide (MetO) reductase A (MsrA) plays an important role in cytoprotection against oxidative stress and serves as a potential drug target. To screen for MsrA regulators, a rapid and specific assay to monitor MsrA activity is required. Most of current assays for MsrA activity are based on the reduction of radioactive substrates such as [3H]-N-acetyl-MetO or fluorescent derivatives such as dimethylaminoazo-benzenesulfonyl-MetO. However, these assays require extraction procedures and special instruments. Here, we developed a specific colorimetric microplate assay for testing MsrA activity quickly, which was based on the fact that MsrA can catalyze the reduction of methyl sulfoxides and simultaneously oxidize dithiothreitol (DTT), whose color can be produced by reacting with Ellman's reagent (dithio-bis-nitrobenzoic acid, DTNB). The corresponding absorbance change at 412nm was recorded with a microplate reader as the reaction proceeded. This method to monitor MsrA activity is easy to handle. Our findings may serve as a rapid method for the characterization of recombinant enzyme and for the screening of enzyme inhibitors, pharmacological activators, gene expression regulators and novel substrates.

Competition between second harmonic generation and two-photon-induced luminescence in single, double and multiple ZnO nanorods.

The nonlinear optical properties of single, double and multiple ZnO nanorods (NRs) were investigated by using a focused femtosecond (fs) laser beam. The excitation wavelength of the fs laser was intentionally chosen to be 754 nm at which the energy of two photons is slightly larger than that of the exciton ground state but smaller than the bandgap energy of ZnO. Second harmonic generation (SHG) or/and two-photon-induced luminescence (TPL) were observed and their dependences on excitation density were examined. For single ZnO NRs, only SHG was observed even at the highest excitation density we used in the experiments. The situation was changed when the joint point of two ZnO NRs perpendicular to each other was excited. In this case, TPL could be detected at low excitation densities and it increased rapidly with increasing excitation density. At the highest excitation density of ~15 MW/cm(2), the intensity of the TPL became comparable to that of the SHG. For an ensemble of ZnO NRs packed closely, a rapid increase of TPL with a slope of more than 7.0 and a gradual saturation of SHG with a slope of ~0.34 were found at high excitation densities. Consequently, the nonlinear response spectrum was eventually dominated by the TPL at high excitation densities and the SHG appeared to be very weak. We interpret this phenomenon by considering both the difference in electric field distribution and the effect of heat accumulation. It is suggested that the electric field enhancement in double and multiple NRs plays a crucial role in determining the nonlinear response of the NRs. In addition, the reduction in the bandgap energy induced by the heat accumulation effect also leads to the significant change in nonlinear response. This explanation is supported by the calculation of the electric field distribution using the discrete dipole approximation method and the simulation of temperature rise in different ZnO NRs based on the finite element method.

Resveratrol preconditioning increases methionine sulfoxide reductases A expression and enhances resistance of human neuroblastoma cells to neurotoxins.

Methionine sulfoxide reductases A (MsrA) has been postulated to act as a catalytic antioxidant system involved in the protection of oxidative stress-induced cell injury. Recently, attention has turned to MsrA in coupling with the pathology of Parkinson's disease, which is closely related to neurotoxins that cause dopaminergic neuron degeneration. Here, we firstly provided evidence that pretreatment with a natural polyphenol resveratrol (RSV) up-regulated the expression of MsrA in human neuroblastoma SH-SY5Y cells. It was also observed that the expression and nuclear translocation of forkhead box group O 3a (FOXO3a), a transcription factor that activates the human MsrA promoter, increased after RSV pretreatment. Nicotinamide , an inhibitor of silent information regulator 1 (SIRT1), prevented RSV-induced elevation of FOXO3a and MsrA expression, indicating that the effect of RSV was mediated by a SIRT1-dependent pathway. RSV preconditioning increased methionine sulfoxide(MetO)-reducing activity in SH-SY5Y cells and enhanced their resistance to neurotoxins, including chloramine-T and 1-methyl-4-phenyl-pyridinium. In addition, the enhancement of cell resistance to neurotoxins caused by RSV preconditioning can be largely prevented by MsrA inhibitor dimethyl sulfoxide. Our findings suggest that treatment with polyphenols such as RSV can be used as a potential regulatory strategy for MsrA expression and function.

Protection of L-methionine against H2O2-induced oxidative damage in mitochondria.

Reactive oxygen species (ROS) is reported to be a critical pathogenic factor and mitochondria is one of the susceptible subcellular organs for oxidative damage. Methionine sulfoxide reductase A (MsrA) is a key anti-oxidant enzyme associated with cytoprotection and previous reports have revealed its importance in mitochondrial function. The anti-oxidation of MsrA is due to Met-centered redox cycle, suggesting that Met-centered redox cycle may play a critical role in mitochondrial protection. L-Methionine (L-Met), a natural amino acid with anti-oxidation activity, can mimic the effect of Met-centered redox cycle. Here, we investigated the protection of L-Met on H(2)O(2)-induced oxidative damage in mitochondria. Our study demonstrated that L-Met protected H(2)O(2)-induced injury in CHO cells. Cytoprotections of L-Met at low concentrations (1-5mM) were abolished by dimethyl sulfoxide (DMSO), a competitive inhibitor of MsrA function, suggesting that these effects may involve the participation of MsrA. Overexpression of MsrA in CHO cells protected mitochondria from H(2)O(2)-induced downtrend of membrane potential and production of mitochondrial superoxide. Pre-treatment with L-Met (1mM) produced a similar effect on the mitochondrial protection against H(2)O(2). Furthermore, it was observed that topical application of L-Met can prevent 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced oxidative damage in the skin of mice. These results suggest that anti-oxidation activity of L-Met may promise a new strategy for the prevention of oxidative stress-induced damage.

[Clinical application of 16-slice spiral CT coronary angiography].

OBJECTIVE: To assess the clinical value of multislice spiral CT coronary angiography (MSCTCA). METHODS: Totally 79 patients were examined with MSCTCA and the CT images were reconstructed by several methods to analyze the factors crucial for the image quality, the ability of MSCT displaying the coronary artery vessels, along with the nature and calcification degrees of the plaques. The presence as well as the degree of vascular stenosis, visualization of the bypass graft, implanted stents and patency of the vessels were evaluated. RESULTS: The left main coronary artery and the left anterior descending artery were all best visualized in 75% R-R phases while the right coronary artery and the left circumflex artery in 62.5% R-R phases. CT images obtained by volume rendering showed the best quality at 75% R-R phases. 16-slice spiral CT was able to display from the primary to the tertiary, and even the quaternary branches of the coronary artery, and clearly displayed the coronary plaques, stenosis, implanted stents and bypass grafts. CONCLUSION: MSCTCA has a good clinical value in the primary identification of coronary heart disease and reexamination after revascularization.