Functional defects of cancer-associated MDC1 mutations in DNA damage repair.

Mediator of DNA damage checkpoint protein 1 (MDC1) serves as a docking platform to promote the localization of various DNA damage response (DDR) components to DNA double-strand break (DSB) sites. MDC1 is vital in controlling proper DDR and maintaining genomic stability. In cancers, genomic instability results from mutations in DNA repair genes and drives cancer development. The mutations of MDC1 in human cancers have not been systematically examined and little is known about the molecular phenotypes caused by these genetic changes. Here, we summarized cancer-associated mutations of MDC1 including insertion/deletion mutations as well as missense mutations in key functional domains of MDC1 from ICGC, TCGA and COSMIC databases. We analyzed 711 somatic mutations of MDC1 across 26 types of human cancers and examined the functional defects of these cancer-associated mutations of MDC1 in the context of DNA damage repair. 6 truncation mutations and 7 missense mutations of MDC1 were chosen for further study. 6 truncation mutations which abolish MDC1-γH2AX interaction abrogate its biological functions in DNA damage repair. 2 missense mutations in FHA domain impaired ATM (ataxia telangiectasia mutated) phosphorylation. 5 missense mutations in BRCT domain also abolished its interaction with γH2AX, resulting in defects in foci formation of MDC1, 53BP1 and BRCA1 as well as defects in G2/M checkpoints. We further used structural modeling to analyze the potential molecular mechanism by which the 7 missense mutations cause the DNA damage repair defects. Taken together, our results reveal these cancer-associated MDC1 mutations can result in functional defects in DNA damage response and may serve as biomarkers for cancer diagnostics in future.

A non-symbiotic novel species, Rhizobium populisoli sp. nov., isolated from rhizosphere soil of Populus popularis.

Strain XQZ8T, isolated from the rhizosphere soil of a Populus popularis plant in China, was characterized using a polyphasic taxonomic approach. Cells were Gram-negative, aerobic, non-spore-forming, and rod-shaped. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain XQZ8T was related to members of the genus Rhizobium and had the highest 16S rRNA gene sequence similarity to Rhizobium smilacinae PTYR-5T (96.6%). The average nucleotide identity and digital DNA-DNA hybridization value between strain XQZ8T and R. smilacinae PTYR-5T were 77.5% and 21.4%, respectively. TYGS whole-genome-based taxonomic and multi-locus sequence analyses of three concatenated housekeeping genes (atpD-recA-glnII) further indicated that strain XQZ8T was a new member of the genus Rhizobium. The major cellular fatty acids included summed feature 8 (C18:1 ω7c/C18:1 ω6c), summed feature 2 (C12:0 aldehyde/unknown 10.928), C16:0, and C19:0 cyclo ω8c. The major respiratory quinones were Q-9 and Q-10. The polar lipids were phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidyldimethylethanolamine, phosphatidylmonomethylethanolamine, an unidentified glycophospholipid, and three unidentified lipids. The genomic DNA G + C content of the strain was 60.1 mol%. Based on the phylogenetic, phenotypic, and genotypic characteristics, strain XQZ8T represents a novel species of the genus Rhizobium, for which the name Rhizobium populisoli sp. nov. is proposed. The type strain is XQZ8T (= JCM 34442T = GDMCC 1.2201T).

In Vitro Antibacterial and Antitumor Activity of Total Triterpenoids from a Medicinal Mushroom Sanghuangporus sanghuang (Agaricomycetes) in Liquid Fermentation Culture.

We analyzed the biological activity and composition of total triterpenoids extracted from the liquid fermentation culture of the medicinal mushroom Sanghuangporus sanghuang. S. sanghuang total triterpenoid extract (STTE) had the strongest inhibitory effect on Staphylococcus aureus, and STTE at 2-fold the minimum inhibitory concentration had a significant effect on the growth of four types of bacteria and caused marked nucleic acid leakage. Scanning electron microscopy confirmed that STTE destroyed bacterial cell walls. STTE also significantly inhibited the proliferation of Caco-2 cells and disrupted their morphology. Flow cytometry revealed that STTE induced cell cycle arrest and induced early and late apoptosis of Caco-2 cells. Infrared spectroscopy, and gas chromatography-mass spectrometry resulted in the detection of a variety of triterpenoids (e.g., pentacyclic triterpenoid, lanolinane triterpenoid, and trans-squalene) as well as other small molecules (e.g., esters, acids, and aldehydes). Our findings indicate that STTE has antibacterial and antitumor activity and will enable screening of novel fungal-derived anticancer and antibacterial compounds.

ZmRAD17 Is Required for Accurate Double-Strand Break Repair During Maize Male Meiosis.

RAD17, a replication factor C (RFC)-like DNA damage sensor protein, is involved in DNA checkpoint control and required for both meiosis and mitosis in yeast and mammals. In plant, the meiotic function of RAD17 was only reported in rice so far. Here, we identified and characterized the RAD17 homolog in maize. The Zmrad17 mutants exhibited normal vegetative growth but male was partially sterile. In Zmrad17 pollen mother cells, non-homologous chromosome entanglement and chromosome fragmentation were frequently observed. Immunofluorescence analysis manifested that DSB formation occurred as normal and the loading pattern of RAD51 signals was similar to wild-type at the early stage of prophase I in the mutants. The localization of the axial element ASY1 was normal, while the assembly of the central element ZYP1 was severely disrupted in Zmrad17 meiocytes. Surprisingly, no obvious defect in female sterility was observed in Zmrad17 mutants. Taken together, our results suggest that ZmRAD17 is involved in DSB repair likely by promoting synaptonemal complex assembly in maize male meiosis. These phenomena highlight a high extent of divergence from its counterpart in rice, indicating that the RAD17 dysfunction can result in a drastic dissimilarity in meiotic outcome in different plant species.

Cancer-associated 53BP1 mutations induce DNA damage repair defects.

TP53 binding protein 1 (53BP1) plays an important role in DNA damage repair and maintaining genomic stability. However, the mutations of 53BP1 in human cancers have not been systematically examined. Here, we have analyzed 541 somatic mutations of 53BP1 across 34 types of human cancer from databases of The Cancer Genome Atlas, International Cancer Genome Consortium and Catalogue of Somatic Mutations in Cancer. Among these cancer-associated 53BP1 mutations, truncation mutations disrupt the nuclear localization of 53BP1 thus abolish its biological functions in DNA damage repair. Moreover, with biochemical analyses and structural modeling, we have examined the detailed molecular mechanism by which missense mutations in the key domains causes the DNA damage repair defects. Taken together, our results reveal the functional defects of a set of cancer-associated 53BP1 mutations.

Quercetin reverses adriamycin resistance by activating GSK-3β/β-catenin pathways through GAS5 in breast cancer cells / 中国临床药理学与治疗学

AIM: To investigate the ability of quercetin to reverse acquire adriamycin (ADR) resistance and explored its probably mechanism. METHODS: The CCK-8 assay was used to detect the cytotoxicity of quercetin in MCF-7/ADR cells and the reversal effect of ADR. The colony formation assay and Hoechst 332582 staining were used to detect the cell proliferation, cell apoptosis and the accumulation of rhodamine 123 (Rh123) respectively. The RNA expression levels of GAS5 and ABCB1 were detected by qRT-PCR. The protein expression levels of GSK-3β, β-catenin, c-MYC, cyclin D1, and ABCB1 were detected by Western blot. RESULTS: Quercetin (10, 20, 40 μmol/L) significantly enhanced the sensitivity of MCF-7/ADR to ADR, inhibitd cell proliferation, and increased the intracellular accumulation of Rh123. Treatment with quercetin in MCF-7/ADR cells, the expression levels of GAS5 and GSK-3β were increased, whereas the expression levels of β-catenin, c-myc, cyclin D1 and ABCB1 were decreased. Further research revealed that reduction of GAS5 by RNA interference (si-GAS5) induced inhibitory effects on the expressions of GAS5 and GSK-3β, and enhanced the expressions of β-catenin, c-myc, cyclin D1, and ABCB1. Furthermore, treatment by quercetin combined with si-GAS5 in MCF-7/ADR cells, the expressions of these proteins were effectively reversed in comparison to quercetin combined with siRNA negative control (sncRNA). CONCLUSION: Quercetin increases the expression of GAS5by GSK-3β/β-catenin signaling pathway, which inhibits the expression of ABCB1, ultimately reversing ADR resistance in the MCF-7/ADR cells.

Quercetin promotes apoptosis of breast cancer cells by targeting GAS5/Notchl signaling pathway / 中国药理学通报

Aim To investigate the possible mechanism of quercetin in promoting apoptosis of breast cancer cells. Methods Breast cancer cells MCF-7 were treated with quercetin. Cell viability was detected by MTT assay, cell proliferation and cloning ability were measured by plate colony formation assay, and cell apoptosis was examined by Annexin V-FITC/PI double staining assay. Meanwhile, MCF-7 cells were treated with quercetin (40, 80, 160 μmol · L

ZmMTOPVIB Enables DNA Double-Strand Break Formation and Bipolar Spindle Assembly during Maize Meiosis.

The meiotic TopoVI B subunit (MTopVIB) plays an essential role in double-strand break formation in mouse (Mus musculus), Arabidopsis (Arabidopsis thaliana), and rice (Oryza sativa), and recent work reveals that rice MTopVIB also plays an unexpected role in meiotic bipolar spindle assembly, highlighting multiple functions of MTopVIB during rice meiosis. In this work, we characterized the meiotic TopVIB in maize (Zea mays; ZmMTOPVIB). The ZmmtopVIB mutant plants exhibited normal vegetative growth but male and female sterility. Meiotic double-strand break formation was abolished in mutant meiocytes. Despite normal assembly of axial elements, mutants showed severely affected synapsis and disrupted homologous pairing. Importantly, we showed that bipolar spindle assembly was also affected in ZmmtopVIB, resulting in triad and polyad formation. Overall, our results demonstrate that ZmMTOPVIB plays critical roles in double-strand break formation and homologous recombination. In addition, our results suggest that the function of MTOPVIB in bipolar spindle assembly is likely conserved across different monocots.

Image inpainting-based behavior image secret sharing.

The polynomial-based image secret sharing (ISS) scheme encodes a secret image into n shadows assigned to n participants. The secret image with high resolution is decoded by Lagrange interpolation when collecting any k or more shadows. Thus, ISS is used in applications such as distributive storage in the cloud, digital watermarking, block chain, and access control. Meaningful shadows are significant in ISS because meaningful shadows decrease the suspicion of image encryption and increase the efficiency of shadow management. Generally, previously meaningful ISS schemes were achieved through embedding the shadows into cover images using information hiding techniques and suffer from large pixel expansion and complex decoding procedure. Digital image processing, such as inpainting (texture synthesis), is a standard technique in multimedia applications. It will be highly significant if ISS can be performed in the processing of a normal digital image processing technique. Generally, the encoding method of an ISS scheme entails the use of a mathematical function that is sensitive to any slight change in the ISS output; therefore, the development of a method for performing the ISS procedure and simultaneously achieving image processing behavior is a key challenge. In this paper, we exploit the behavior ISS (BISS) and realize an image inpainting-based BISS scheme for the (k, n) threshold. Using screening operations, a secret image is encoded into the pixels of cover images by polynomial-based ISS in the processing of inpainting shadows to obtain meaningful shadows similar to the input cover images. In addition, the secret image can be losslessly decoded by Lagrange interpolation when collecting any k or more shadows. Experiments are given to confirm the efficiency of the scheme.

Selective Electrocatalytic Water Oxidation to Produce H2O2 Using a C,N Codoped TiO2 Electrode in an Acidic Electrolyte.

Production of hydrogen peroxide (H2O2) via in situ electrochemical water oxidation possesses great potential applications in the energy and environment fields. In this work, for the first time, we reported a C,N codoped TiO2 electrode for selective electrocatalytic water oxidation to produce H2O2 in an acidic electrolyte. An electrochemical anodic oxidation method combined with postcalcination in the presence of urea was applied to fabricate such a C,N codoped TiO2 electrode, which was evidenced by detail structural characterizations. The calcination temperature and urea atmosphere were found to play key roles in its catalytic performances; the optimized 600N sample exhibited an onset potential of 2.66 V (vs Ag/AgCl) and a Tafel slope of 51 mV dec-1 at pH 3. Under the optimal applied potential, the cumulative H2O2 concentration for this sample reached 0.29 µmol L-1 cm-2 h-1. More importantly, a simple recalcination strategy was developed to recover the deactivation electrode. This study proposed an efficient C,N codoped TiO2 electrode toward water oxidation to selectively produce H2O2 in the acidic electrolyte, which could be further used to in situ generate H2O2 for the energy- and environment-related fields with water as the precursor.

Effect of icariin on early βdefensin2 and T cell subsets in rats after tracheotomy / 中南大学学报(医学版)

OBJECTIVES@#To investigate the effect of icariin (ICA) on early β-defensin-2 and T cell subsets in rats after tracheotomy.@*METHODS@#A total of 54 SPF male Sprague-Dawley rats were randomly divided into a normal control group (group A), a model group (group B), and a model+ICA treatment group (group C), with 18 rats in each group. A tracheotomy intubation model of the B and C group was prepared. After 6 h of surgery, ICA intervention was given to group C. Groups A and B were given the same amount of normal saline. Lung tissue, alveolar lavage fluid and peripheral blood were taken at 24 h, 72 h and 168 h, respectively. The expression of rat β-defensin-2 mRNA in lung tissue was detected by RT-PCR. The content of β-defensin-2 in alveolar lavage fluid and peripheral blood serum was detected by ELISA. The content of peripheral blood T cell subsets (CD3, CD4, CD8) was detected by flow cytometry, and the ratio of CD4/CD8 was calculated.@*RESULTS@#After tracheotomy, the levels of β-defensin-2 mRNA and β-defensin-2 in lung tissue from the group B were increased significantly at 24 h, then they were decreased gradually, and decreased most significantly at 168 h (0.05). The level of CD3 T cells in peripheral blood was significantly lower than that in the group A (0.05). After ICA intervention in group C: lung tissue, alveolar lavage fluid, peripheral blood serum β-defensin-2 content, and peripheral blood CD3 and CD4 T cell levels were gradually increased, significantly higher than those in the group B (<0.05). CD8 T cell level was significantly lower than that in the group A at 24 h (<0.05), the CD4/CD8 ratio was significantly higher at 168 h than those in the group A or B (both <0.01).@*CONCLUSIONS@#ICA can improve the early lung immune function in rats with tracheotomy, which might be related to up-regulation of β-defensin-2 in lung tissue and alveolar lavage fluid, concomitant with increases in CD3 and CD4 T cells and CD4/CD8 ratio in peripheral blood while reduction in CD8 cells.

Effectiveness of Prophylactic Use of Antibiotics for Preventing Infection after Acute Stroke ：A Meta-analysis / 中国药房

OBJECTIVE：To systematically evaluate the effectiveness of prophylactic use of antibiotics for infection after acute stroke，and to provide evidence-based reference for clinical treatment for infection after acute stroke. METHODS ：Retrieved from PubMed，Embase，Cochrane library ，CJFD，VIP，Wanfang database and trial registration platforms such as Central ，randomized controlled trials （RCTs）about the effectiveness of prophylactic use of antibiotics （trial group ）versus placebo or non-prophylactic use of antibiotics （control group ）in the prevention of infection after acute stroke were collected during the inception to Dec. 2019. After data extraction ，the quality of included literatures were evaluated with Cochrane bias risk assessment tool 5.1.0 and modified Jadad scale. Meta-analysis was carried out by using Rev Man 5.3 statistical software. GRADE system was used to analysis the result of Meta-analysis. RESULTS ：A total of 7 RCTs were included ，involving 4 310 patients. The results of Meta-analysis showed that there was no statistical significance in the mortality of patients [RR ＝1.05，95％CI（0.92，1.20），P＝0.47] or the incidence of pneumonia [RR ＝0.92，95％CI（0.77，1.11），P＝0.40] between 2 groups. The total infection rate [RR ＝0.69，95％CI（0.57， 0.85），P＝0.000 3] and the incidence of urinary tract infection [RR ＝0.38，95％CI（0.29，0.49），P＜0.000 01] in the trial group were significantly lower than control group ，and the difference was statistically significant. Result of GRADE showed the out- comes were in high-quality grade. CONCLUSIONS ：Prophylactic use of antibiotics can reduce the total infection rate and the incidence of urinary tract infection after acute stroke ，but can not significantly affect the mortality and the incidence of pneumonia.

Advances Towards How Meiotic Recombination Is Initiated: A Comparative View and Perspectives for Plant Meiosis Research.

Meiosis is an essential cell-division process for ensuring genetic diversity across generations. Meiotic recombination ensures the accuracy of genetic interchange between homolous chromosomes and segregation of parental alleles. Programmed DNA double-strand breaks (DSBs), catalyzed by the evolutionarily conserved topoisomerase VIA (a subunit of the archaeal type II DNA topoisomerase)-like enzyme Spo11 and several other factors, is a distinctive feature of meiotic recombination initiation. The meiotic DSB formation and its regulatory mechanisms are similar among species, but certain aspects are distinct. In this review, we introduced the cumulative knowledge of the plant proteins crucial for meiotic DSB formation and technical advances in DSB detection. We also summarized the genome-wide DSB hotspot profiles for different model organisms. Moreover, we highlighted the classical views and recent advances in our knowledge of the regulatory mechanisms that ensure the fidelity of DSB formation, such as multifaceted kinase-mediated phosphorylation and the consequent high-dimensional changes in chromosome structure. We provided an overview of recent findings concerning DSB formation, distribution and regulation, all of which will help us to determine whether meiotic DSB formation is evolutionarily conserved or varies between plants and other organisms.

Decrease in DNA methylation 1 (DDM1) is required for the formation of m CHH islands in maize.

DNA methylation plays a crucial role in suppressing mobilization of transposable elements and regulation of gene expression. A number of studies have indicated that DNA methylation pathways and patterns exhibit distinct properties in different species, including Arabidopsis, rice, and maize. Here, we characterized the function of DDM1 in regulating genome-wide DNA methylation in maize. Two homologs of ZmDDM1 are abundantly expressed in the embryo and their simultaneous disruption caused embryo lethality with abnormalities in cell proliferation from the early stage of kernel development. We establish that ZmDDM1 is critical for DNA methylation, at CHG sites, and to a lesser extent at CG sites, in heterochromatic regions, and unexpectedly, it is required for the formation of m CHH islands. In addition, ZmDDM1 is indispensable for the presence of 24-nt siRNA, suggesting its involvement in the RdDM pathway. Our results provide novel insight into the role of ZmDDM1 in regulating the formation of m CHH islands, via the RdDM pathway maize, suggesting that, in comparison to Arabidopsis, maize may have adopted distinct mechanisms for regulating m CHH.

Impact of metabolic syndrome on clinicopathological characteristics and survival of patients with colorectal cancer / 中华全科医师杂志

Objective To examine the impact of metabolic syndrome (MS) on the clinicopathological characteristics and prognosis of patients with colorectal cancer (CRC).Methods The clinical data of 650 patients with CRC admitted in Shanxi Provincial Cancer Hospital between January 2010 and December 2011 were retrospectively analyzed.Among 650 patients there were 190 cases complicated with MS (MS group) and 460 cases without MS (non-MS group),the clinicopathological features and prognosis were compared between two groups.Results The serum insulin and insulin-like growth factor-1 (IGF-1) levels in MS group were significantly higher than those in non-MS group [(9.2±4.7) vs.(6.8±4.7)μIU/L,t=8.88,P＜0.01 and (200.2±44.1) vs.(136.7±63.2)mg/L,t=12.63,P＜0.01].The proportions of stage T3 and T4 cancer,extra-regional lymph node metastasis (ELN),and TNM stage Ⅲ and Ⅳ patients in MS group were significantly higher than those in non-MS group [(83.2％ (158/190) vs.72.6％ (334/460),x2=8.19,P=0.04;9.5％ (18/190) vs.4.8％(22/460),x2=8.61,P=0.04;56.3％ (107/190) vs.45.2％(208/460),x2=8.22,P=0.04,respectively].The 5-year disease-free survival (DFS) in MS group was significantly lower than that in non-MS group [57.9％(99/171)vs.66.1％(279/422),P＜0.01].Multivariate analysis indicated that MS(HR=1.623,95％CI:1.511-1.963,P=0.03),IGF(HR=1.382,95％CI:1.031-1.765,P=0.02) and,ELN(HR=4.270,95％CI:2.177-7.463,P＜0.01)were independent factors affecting the prognosis of CRC patients.Conclusion Metabolic syndrome is one of the risk factors affecting the prognosis of CRC patients.

Impact of metabolic syndrome on clinicopathological characteristics and survival of patients with colorectal cancer / 中华全科医师杂志

Objective@#To examine the impact of metabolic syndrome (MS) on the clinicopathological characteristics and prognosis of patients with colorectal cancer (CRC).@*Methods@#The clinical data of 650 patients with CRC admitted in Shanxi Provincial Cancer Hospital between January 2010 and December 2011 were retrospectively analyzed. Among 650 patients there were 190 cases complicated with MS (MS group) and 460 cases without MS (non-MS group), the clinicopathological features and prognosis were compared between two groups.@*Results@#The serum insulin and insulin-like growth factor-1 (IGF-1) levels in MS group were significantly higher than those in non-MS group [(9.2±4.7) vs.(6.8±4.7)μIU/L, t=8.88, P<0.01 and (200.2±44.1) vs.(136.7±63.2)mg/L,t=12.63, P<0.01]. The proportions of stage T3 and T4 cancer, extra-regional lymph node metastasis (ELN), and TNM stage Ⅲ and Ⅳ patients in MS group were significantly higher than those in non-MS group [(83.2% (158/190) vs. 72.6% (334/460), χ2=8.19, P=0.04; 9.5% (18/190) vs. 4.8%(22/460),χ2=8.61, P=0.04; 56.3% (107/190) vs. 45.2%(208/460), χ2=8.22, P=0.04, respectively]. The 5-year disease-free survival (DFS) in MS group was significantly lower than that in non-MS group [57.9%(99/171)vs. 66.1%(279/422), P<0.01]. Multivariate analysis indicated that MS(HR=1.623, 95%CI:1.511-1.963, P=0.03), IGF(HR=1.382, 95%CI:1.031-1.765, P=0.02) and, ELN(HR=4.270, 95%CI:2.177-7.463, P<0.01)were independent factors affecting the prognosis of CRC patients.@*Conclusion@#Metabolic syndrome is one of the risk factors affecting the prognosis of CRC patients.

[Driving Factors of the Dynamics of Microbial Community in a Dam of Copper Mine Tailings].

The relative importance of the deterministic versus stochastic processes underlying community dynamics has long been a central theme in community ecology, and is intensively debated in the field. Microbial communities play key roles in nutrient cycling and the flow of energy in ecosystems. The research on the structural dynamics of microbial community will provide data and theoretical support for understanding the assembly mechanisms of community, and for predicting the dynamics of microbial community under environmental stress. In this study, the Illumina MiSeq method was applied to investigate the structural dynamics of bacterial and fungal community in a dam of Shibahe mine tailings at different restoration stages (1-45 years). The results indicated that the soil physicochemical properties in the dam of mine tailings formed an ecological gradient, and the plant community showed succession along the restoration time. The diversity of plant communities was significantly correlated with soil nutrient contents but not with soil heavy metal contents. The structure of the microbial communities showed significant differences at different restoration stages of the dam land, in which Proteobacteria, Actinobacteria, Firmicutes, and Acidobacteria were the dominant bacterial phyla, and Ascomycota, Basidiomycota, and Zygomycota were the dominant fungal phyla. The assembly of the microbial community was shaped mainly by the soil nutrients and soil heavy metal contents, but plant diversity had no significant effect on the microbial community structure. It was suggested that edaphic factors drive the dynamics of microbial communities under the stress conditions of pH and heavy metals on small, local scales.

[Spatiotemporal dynamics and driving forces of soil bacterial communities on the dam of Shibahe copper mine tailings in Shanxi, China.] / åå «æ²³é“œå°¾çŸ¿åº“åé¢ç»†èŒç¾¤è½æ—¶ç©ºåŠ¨æ€åŠå ¶é©±åŠ¨åŠ›.

The maintaining mechanism of community diversity is the core of community ecology. The mine tailing is a good field for studying on the underlying mechanism of community diversity, as a kind of original bare land with heavy metal pollution, where the physicochemical characteristics of soil change with the restoration periods. We examined the driving forces for bacterial community diversity based on the investigation of edaphic factors, plant community, and bacterial communities in Shibahe copper mine tailing, Shanxi. The results showed that nutrient contents in soil increased with restoration periods. The seasonal dynamics of soil nutrient in different restoration time were different. Shannon diversity and richness of bacterial community showed an increasing trend, indicating community stability was improved with restoration. Influenced by plant community, the seasonal changes of those indices differed with restoration. Results from the RDA analysis showed that the diversity and structure of bacterial communities were determined by environmental factors (edaphic, plant and heavy metals). Results from the structure equation models further confirmed that soil nutrients (TC, TN, NO3--N, NO2-N), plant community, and soil enzyme activities jointly drove bacterial community assembly on the copper mine tailings.

Transient rotation of photospheric vector magnetic fields associated with a solar flare.

As one of the most violent eruptions on the Sun, flares are believed to be powered by magnetic reconnection. The fundamental physics involving the release, transfer, and deposition of energy have been studied extensively. Taking advantage of the unprecedented resolution provided by the 1.6 m Goode Solar Telescope, here, we show a sudden rotation of vector magnetic fields, about 12-20° counterclockwise, associated with a flare. Unlike the permanent changes reported previously, the azimuth-angle change is transient and cospatial/temporal with Hα emission. The measured azimuth angle becomes closer to that in potential fields suggesting untwist of flare loops. The magnetograms were obtained in the near infrared at 1.56 µm, which is minimally affected by flare emission and no intensity profile change was detected. We believe that these transient changes are real and discuss the possible explanations in which the high-energy electron beams or Alfve'n waves play a crucial role.

Poly(lactic acid) electrospun fiber membranes carrying gemcitabine hydrochloride inhibit the growth of bone tumor / 中国组织工程研究

BACKGROUND:Gemcitabine hydrochloride is a water-soluble anticancer drug that induces apoptosis in tumor cells, but it has an excessive release in vivo. OBJECTIVE:To evaluate the effect of poly(lactic acid) (PLA) electrospun fiber membranes carrying gemcitabine hydrochloride on the growth of human osteosarcoma cell lines MG-63. METHODS:PLA electrospun fiber members with (experimental) or without (control) gemcitabine hydrochloride were fabricated and characterized. Two kinds of fiber membranes were immersed in low-glucose DMEM medium, and the supernatants were collected in the two groups at 3, 5, 7 days, respectively. Passage 5 human osteosarcoma cell lines MG-63 were inoculated into 96-well plates containing low-glucose DEME with 15％ fetal bovine serum, and divided into seven groups. Groups 1-3 were cultured in the experimental supernatants of 3, 5, 7 culture days, and groups 4-6 were cultured in the control supernatants of 3, 5, 7 culture days, respectively. The remaining group acted as the negative control with no supernatant. Thereafter, cell counting kit-8 was used to detect cell proliferation, and RT-PCR was used to measure expression of Bcl-2 and Bax at 3 days of culture. RESULTS AND CONCLUSION:(1) No obvious particle was found on the smooth and even surface of the fiber members in the experimental and control groups. There was no significant difference in fiber diameter, contact angle and tensile strength between the two kinds of fiber membranes. (2) The results of cell counting kit-8 showed that compared with the negative control group, the supernatant released from the control group had no effect on the MG-63 proliferation at different time points, while the supernatant released from the experimental group could inhibit the MG-63 proliferation at different time points (P<0.05), and the inhibitory effect became more and more obvious with the prolongation of release time. (3) RT-PCR findings showed that compared with the control group, the supernatant released from the experimental group could increase Bax mRNA expression and decrease Bcl-2 mRNA expression at the same time point. To conclude, the PLA electrospun fiber membranes carrying gemcitabine hydrochloride can sustainably inhibit MG-63 proliferation and promote cell apoptosis.