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Previous studies have determined that magnesium (Mg) in appropriate concentrations prevents plants from suffering from abiotic stress. To better understand the mechanism of Mg alleviation of aluminum (Al) stress in apple, we investigated the effect of Mg on plant growth, photosynthetic fluorescence, antioxidant system, and carbon (C) and nitrogen (N) metabolism of apple seedlings under Al toxicity (1.5 mmol/L) via a hydroponic experiment. Al stress induced the production of reactive oxygen in the leaves and roots and reduced the total dry weight (DW) by 52.37 % after 20 days of treatment relative to plants grown without Al, due to hindered photosynthesis and alterations in C and N metabolism. By contrast, total DW decreased by only 11.07 % in the Mg-treated plants under Al stress. Supplementation with 3.0 mmol/L Mg in the Al treatment decreased Al accumulation in the apple plants and reduced Al-induced oxidative damage by enhancing the activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidase) and reducing the production of H

Nitrogen (N) is an essential element for plant growth, development, and metabolism. In apple production, the excessive use of N fertilizer may cause high N stress. Whether high N stress can be alleviated by regulating potassium (K) supply is unclear. A hydroponics experiment was conducted herein to test the influence of different N and K conditions on the root morphology and physiology of apple M9T337 rootstocks. The results showed that high nitrate-N conditions caused the dysregulation of N/K balance, hormone content, and antioxidant metabolism, resulting in damage to the root cortex structure. High nitrate conditions caused stomatal closure and reduced mesophyll conductance ( g) and the maximum carboxylation efficiency ( V), thus increasing photosynthetic limitations, and also reduced the expression of sugar transporter proteins ( MdSOT1, MdSOT2, and MdSUT1), leading to a lower soluble sugar content in the root system, which was detrimental to root growth. Further analysis found that appropriately increasing the K supply (10 mM) enhanced the superoxide dismutase, peroxidase, and ascorbate peroxidase activities, reduced the malondialdehyde and H O contents, and protected the root structure. It also optimized the net photosynthetic rate ( A), increased sugar transporter protein expression and sugar-metabolizing enzyme activity in the roots, promoted the transport of photosynthetic products such as sorbitol and sucrose from the leaves to the roots, and increased the soluble sugar content in the roots. In summary, our data show that an appropriate increase in the K supply (10 mM) alleviated the root inhibition of high N through regulating physiological metabolic activities such as the antioxidant system and carbon metabolism. These findings support the use of N and K for alleviating high-N stress.

Excessive nitrogen (N) supply often leads to an imbalance of carbon (C) and N metabolism and inhibits plant growth. Sucrose, an important source and signaling substance of C in plants, is closely linked to N metabolism. However, it is not clear whether exogenous sucrose can mitigate the inhibitory effect of high N on plant growth by regulating C and N metabolism. In this study, we investigated the effects of exogenous sucrose on the growth, N metabolism, and C assimilation in the apple rootstock M26 seedlings under normal (5 mM NO

The outbreak of the coronavirus disease (COVID-19) pandemic, a significant health threat, influenced information-related behaviors and induced increased rumor-sharing behaviors on social media. Fighting COVID-19 thus entails the need to fight the rumors as well, providing a strong motivation to explore rumor-related behavior during this extraordinary period. From the perspective of information acquisition, we predicted that information acquisition from social and traditional media would interactively influence rumor-related decisions (i.e., rumor belief and sharing) and that critical thinking would shape this relationship. Through a survey of 2424 individuals who used social media during the pandemic, we found that information acquisition from social media was negatively related to rumor sharing and that rumor belief mediated this relationship. Meanwhile, information acquisition from traditional media weakened the negative effect of information acquisition from social media on rumor belief, and critical thinking alleviated the positive effect of rumor belief on rumor sharing. This study contributes to the literature by explaining the diffusion of COVID-19 rumors on social media from an information perspective and revealing how different information sources and thinking styles come into conflict in rumor decisions.

In order to define translocation characteristics of 13C-photoassimilates to fruit during the fruit development stage in 'Fuji' apple, the 13C labeled tracer method was used in whole five-year-old 'Fuji'3/M26/Malus hupehensis (Pamp.) Rehder apple trees at different days after flowering (DAF). The changes in 13C translocation to the fruit, source strength of the leaves, and sink strength of the fruits were assessed. The results indicated that the δ13C value and 13C distribution rate of the fruit increased first and then decreased with the increase in the fruit development period, being higher from 120 to 135 DAF. The leaves appeared to moderately senesce in an attempt to maintain high photosynthesis during 120-135 DAF, which promoted the outward transport of photoassimilates. The single fruit weight and longitudinal and transverse diameter of the fruit increased rapidly during 120-150 DAF, which increased the sink zone for the unloading of photoassimilates in the fruit. The activity of sorbitol dehydrogenase (SDH) and amylase (AM), the content of indole-3-acetic acid (IAA), the gibberellin (GA3) and abscisic acid (ABA) in the fruit flesh, and the gene expression levels of MdSOT1, MdSOT2, MdSOT3, MdSUT1, and MdSUT4 in the fruit stalk tissue were higher during 120-135 DAF. At this point, the difference in the sorbitol content between the fruit stalk and fruit flesh was also at the highest level of the entire year. These factors together increased the sink activity of the fruit, thus improving the photoassimilate transport efficiency to the fruit.

Excessive application of nitrogen (N) fertilizer is common in Chinese apple production. High N reduced the contents of soluble sugar and total flavonoids by 16.05 and 19.01%, respectively, resulting in poor fruit quality. Moreover, high N increased the total N and decreased the total C and C/N ratio of apple fruits. On the basis of the transcriptomic, proteomic, and metabolomic analyses, the global network was revealed. High N inhibited the accumulation of carbohydrates (sucrose, glucose, and trehalose) and flavonoids (rhamnetin-3-O-rutinoside, rutin, and trihydroxyisoflavone-7-O-galactoside) in fruits, and more C skeletons were used to synthesize amino acids and their derivatives (especially low C/N ratio, e.g., arginine) to be transferred to N metabolism. This study revealed new insights into the decline in soluble sugar and flavonoids caused by high N, and hub genes (MD07G1172700, MD05G1222800, MD16G1227200, MD01G1174400, and MD02G1207200) and hub proteins (PFK, gapN, and HK) were obtained.

In order to define translocation characteristics of

In China, excessive application of nitrogen (N) fertilizer is common in intensive apple production. To resolve issues of benefit reduction and environmental pollution caused by excessive N, a two-year trial was conducted in an apple orchard with a split-plot design, in which the main factor was the N level (500, 400, 300, and 200 kg N ha−1 year−1, expressed as TN, TN80%, TN60%, and TN40%, respectively) and the deputy factor was whether or not to add 3,4-dimethylpyrazole phosphate (DMPP, expressed as +D). The effects of N reduction combined with DMPP on soil N transformation, fruit quality, economic benefits, and environmental effects were investigated. The results showed that DMPP reduced the production of nitrate and its vertical migration by inhibiting the abundance of AOB amoA and decreased N2O emission by reducing nirKC1 levels. Moreover, N reduction combined with DMPP improved N use efficiency (26.67–49.35%) and reduced N loss rate (15.25–38.76%). Compared with TN, TN60% + D increased the content of anthocyanin and soluble sugar by 21.15% and 13.09%, respectively, and decreased environmental costs caused by NH3 volatilization and N2O emission by 33.84%, while maintaining yield and N utilization rate at relatively high levels. Considering the agronomic, economic and environmental benefits, on the basis of traditional N application rate, 40% N reduction combined with DMPP (TN60% + D) could ensure target yield, corresponding quality and economic benefits, maintain soil N fertility, and reduce the risk of N losses to the environment. The present research could provide references for green, efficient, and sustainable development of apple production.

In order to improve the problem of poor coloring caused by high fruit nitrogen in apple production, we studied the effects of different concentrations of abscisic acid (ABA: 0, 50, 100, and 150 mg/L) and fluridone (ABA biosynthesis inhibitor) on the fruit of ‘Red Fuji’ apple (Malus Domestica Borkh.) in the late stage of apple development (135 days after blooming) in 2017 and 2018. The effects of these treatments on the distribution of 13C and 15N and anthocyanin synthesis in fruit were studied. The results showed that the expression levels of ABA synthesis and receptor genes in the peel and flesh were upregulated by exogenous ABA treatment. An appropriate concentration of ABA significantly increased the expression of anthocyanin synthesis genes and transcription factors and increased the content of anthocyanin in the peel. The results of 13C and 15N double isotope labeling showed that exogenous ABA coordinated the carbon–nitrogen nutrient of apple fruit in the late stage of the development, reduced the accumulation of fruit nitrogen, increased the accumulation of fruit carbon and sugar, provided a substrate for anthocyanin synthesis, or promoted anthocyanin synthesis through the sugar signal regulation mechanism. Comprehensive analysis showed that the application of 100 mg/L ABA effectively improved the problem of poor coloring caused by high fruit nitrogen in the late stage of apple development and is beneficial to the accumulation of carbon in fruit and the formation of color.

Inhibiting the overgrowth of autumn branches during the fruit enlargement stage is one important way to improve the quality of apple fruits. Here, four levels of paclobutrazol (PBZ) (0, 500, 1000, 1500, and 2000 mg·L−1) were applied to the autumn branch leaves of five-year-old ‘Fuji’ apple (Malus × domestica Borkh.) trees at the fruit enlargement stage in 2018 and 2019. The results showed that increasing PBZ levels decreased indole-3-acetic acid (IAA) and gibberellic acid (GA3) contents and increase abscisic acid (ABA) contents in the autumn branch leaves. PBZ also reduced the leaf area, branch length, leaf number, and Rubisco enzyme activity in the autumn branches, but had no significant effect on chlorophyll and net photosynthetic rate. Obvious changes occurred when the concentration of PBZ exceeded 1500 mg·L−1, including the inhibition of autumn branch growth. 13C and 15N isotope labeling results indicated that PBZ coordinated the carbon–nitrogen nutrition of autumn branches in the fruit enlargement stage, reduced the δ13C and nitrogen derived from fertilizer (Ndff) in the leaves of autumn branches. PBZ also coordinated the carbon–nitrogen nutrition of fruits, reduced the accumulation of nitrogen in the fruit and increased the accumulation of carbon in the fruit. PBZ increased the content of soluble sugar, starch, soluble protein, and free amino acids in the roots to varying degrees in early spring the following year (2019 and 2020). These results indicated that a moderate PBZ (1000–1500 mg·L−1) application could reasonably regulate carbon-nitrogen nutrition of autumn branches and fruits, then improve fruit quality and the storage nutrition of apple trees.

To compare the effects between gene therapy and gradual release carrier for bone morphogenetic protein-2 (BMP-2) in repairing bone defects, bone defects for 15 mm were created.on the bilateral radius in rabbits and treated with four kinds of implantations, ie, composite of transgeneic MSCs and PLA/PCL (Group A), composite of MSCs and gradual release carrier for BMP-2 (Group B), composite of MSCs and PLA/PCL (Group C), and PLA/PCL alone (Group D). After 4, 8, and 12 weeks of the operations, X-ray, histological examination, biomechanics analysis, and bone density measurement were conducted. Results showed that both osteoblasts and mesenchymal cells displayed strongly positive expression of BMP-2 in Group A after 4 weeks of the operation, the speed and quality of bone formation in Group A were much better than those in Group B. After 12 weeks of the operations, bone defects were completely repaired in Group A. BMP-2 gene therapy is really a good method to repair segmental bone defects.

On the basis of perfect PC2D simulation to the measured current density vs voltage (J–V) curve of the best selective emitter (SE) solar cell fabricated by the CSG Company using the screen printing phosphoric paste method, we systematically investigated the effect of the parameters of gridline, base, selective emitter, back surface field (BSF) layer and surface recombination rate on performance of the SE solar cell. Among these parameters, we identified that the base minority carrier lifetime, the front and back surface recombination rate and the ratio of the sheet-resistance of heavily and lightly doped region are the four largest efficiency-affecting factors. If all the parameters have ideal values, the SE solar cell fabricated on a p-type monocrystalline silicon wafer can even obtain the efficiency of 20.45%. In addition, the simulation also shows that fine gridline combining dense gridline and increasing bus bar number while keeping the lower area ratio can offer the other ways to improve the efficiency.

Seeding is the crucial step in bone tissue engineering. In current study, static and dynamic seeding methods for human bone marrow stem cells (hBMSCs) were compared. The methods for assay of DNA content in the constructs after seeding were adopted. The optic microscopy for histological apearance and the scanning electron microscopy (SEM) and fluorescent RT-PCR for osteogenic markers were performed. The maximal initial seeding concentration in static seeding is lower than that in dynamic seeding. Histology and SEM revealed the even distribution and spreading of cells in the dynamically seeded constructs, but showed cell aggregation in the statically seeded counterparts. Fluorescent RT-PCR again revealed stronger osteogenic potential of dynamically seeded constructs. Therefore, this initial study demonstrated that dynamic seeding of human bone marrow stem cells is a promising technique in bone tissue engineering.

To study the effect of direct bone morphogenetic protein 2 (BMP-2) gene therapy mediated by adenovirus on repairing bone defect.The radial defect models were made on 60 rabbits, which were evenly divided into 4 groups randomly. The 4 groups were treated with different materials: group A, adenovirus carrying BMP-2 gene (Ad-BMP-2) plus bovine cancellous bone (BCB); group B, reconstructed BMP-2 plus BCB; group C, Ad-Lacz plus BCB; and group D, only BCB scaffolds. The X-ray, histological examination, biomechanics analysis, and immunohistochemical staining were made 4, 8, and 12 weeks after the operation.Group A gained better effect in the volume of new bones, the anti-bending intensity of the healing bone, and the expression of BMP-2 than those of group B. The defect in group A was healed. No new bones were observed in group C and group D.Direct BMP-2 gene therapy is easy to perform and has very strong osteo-induction ability. It is a good method to repair segmental bone defects.

Copolymer of polycaprolactone (PCL) and polylactic acid (PLA) was synthesized and catalyzed using Y (CF3COO)3/AL (I-Bu)3. The biocompatibility was evaluated by means of biochemistry, immunocytochemistry, and by cytotoxity test. This novel orthopedic biodegradable polymer can serve as an ideal orthopedic biodegradable implants, and adjustment of molecular weight and ratio of polymers can control its degradation period.

Shock waves were elicited by transient pressure disturbances, which could be used to treat musculoskeletal disorders. In present studies, we investigated whether the low-density shock waves (LDSWs), which are able to damage plasma membrane without impairing the vimentin or other organelles, might augment T-cell proliferation as well as IL-2 expression, and if mitogen activated protein kinase p38 (p38 MAPK) might be an underlying mechanism through which the LDSWs enhanced T-cell function. We found that the LDSWs increased activation of p38 MAPK in Jurkat T cells. The LDSWs alone didn't result in the T-cell proliferation and IL-2 expression. However, in combination with other stimuli, LDSWs could augment the T-cell proliferation and IL-2 expression. Inhibition of p38 MAPK using SB203580 reduced the stimulatory effects of the LDSWs, which indicated that the LDSWs enhanced IL-2 expression through a mechanism that involved p38 MAPK activation. We concluded that the p38 MAPK activation played a key role in the regulation of T cells function by the LDSWs.

In this study, porous polymer (PLA/PCL) membrane was first treated with ethanol to become hydrophilic, and then immersed into DMEM with 50% fetal bovine serum to enhance the affinity to cells. MSCs cultured in osteogenic medium were loaded into the membrane at density of 5 x 10(6)/cm2 for 7 days, and scanning electrical microscope was used to observe the growth of the MSCs. The growth of MSCs inside the constructs was functionally well, and the cells proliferated with the time of culture. We concluded from current study that the membrane had satisfactory biocompatibility and the constructs could be used to guided bone regeneration.

Clinical and research reports concerning orthopedic biodegradable implants were reviewed. The clinical results were analyzed in terms of complications and compatibility. The possible applications of the implants and further research fields were summarized.

OBJECTIVE: To improve the results of the treatment of unstable types of intertrochanteric fractures of the femur (ITFF) by internal fixation. METHODS: A L-trapezoid compression plate system (L-TCP) was designed and compared to the AO/ASIF angle plates of 95 and 130 (L-AP) with mechanical tests. An Evans Type III model was made, the simulation electrical test with loading on single and both legs were done. The results demonstrated that the stability of the L-TCP fixation was significantly greater, and the stress concentration at the upper screw hole was relevantly smaller than that of L-AP. From June 1986 to June 1998, 82 patients of ITFF were treated with L-TCP fixation. The average age was 67.4 years old (26-91). Seventy-four of those fractures were unstable. Fifty-eight patients were treated with open reduction, and 24 cases were treated by closed reduction and limited open (only lateral aspect of upper femur was exposed) fixation with L-TCP under X-ray monitoring. RESULTS: Sixty-six patients were followed up for 6-69 months. Complications, including 3 wound infection, 1 non-union, 3 coxa varus and 2 implant breakage (9 complications of 7 cases), all occurred in the open reduction group. No complication was found in the closed reduction group. CONCLUSIONS: In the treatment of ITFF, the results of closed reduction and limited open fixation with L-TCP is significantly better than that of open reduction and fully exposed fixation.

To compare the results of femoral head replacement (FHR) and total hip replacement (THR) in treatment of subcapital femoral neck fractures (SFNF).Between May 1987 and July 1998, 56 elderly patients (6 5-90 years; average 73.5 years) with SFNF were treated with prosthetic replacement. Six cases were treated with unipolar FHR, 18 cases with Bateman bipolar FHR, and 32 cases with Bateman bipolar THR. All domestic prostheses were installed with cement.There was no significant difference between the 2 groups in operating time and blood transfusion. Forty-nine patients were followed-up for an average of 5 years and 10 months. No wound infection or death was related to surgery. Complications in Group FHR were significantly higher than that i n Group THR.Since FHR is difficult to fit the bony acetabulum, it is only indicated for senile cases with poor conditions. However, the bi polar THR installed with cement is indicated for most elderly patients. Since th e femoral head and acetabulum can fit each other completely, it is more stable for taking weight-bearing earlier with less complications.