Simultaneous production of high-frequency synthetic apomixis with high fertility and improved agronomic traits in hybrid rice.

The current apomixis system used in fixing heterozygosity suffers from the problems of low fertility and limited apomixis induction rate. This study implies that egg-cell-specific expression of dandelion's PAR combined with MiMe in hybrid rice can efficiently trigger highly fertile synthetic apomixis for effective clonal propagation of hybrids.

The CHCHD2/Sirt1 corepressors involve in G9a-mediated regulation of RNase H1 expression to control R-loop.

R-loops are regulators of many cellular processes and are threats to genome integrity. Therefore, understanding the mechanisms underlying the regulation of R-loops is important. Inspired by the findings on RNase H1-mediated R-loop degradation or accumulation, we focused our interest on the regulation of RNase H1 expression. In the present study, we report that G9a positively regulates RNase H1 expression to boost R-loop degradation. CHCHD2 acts as a repressive transcription factor that inhibits the expression of RNase H1 to promote R-loop accumulation. Sirt1 interacts with CHCHD2 and deacetylates it, which functions as a corepressor that suppresses the expression of downstream target gene RNase H1. We also found that G9a methylated the promoter of RNase H1, inhibiting the binding of CHCHD2 and Sirt1. In contrast, when G9a was knocked down, recruitment of CHCHD2 and Sirt1 to the RNase H1 promoter increased, which co-inhibited RNase H1 transcription. Furthermore, knockdown of Sirt1 led to binding of G9a to the RNase H1 promoter. In summary, we demonstrated that G9a regulates RNase H1 expression to maintain the steady-state balance of R-loops by suppressing the recruitment of CHCHD2/Sirt1 corepressors to the target gene promoter.

[Evaluation of eutrophication level changes in Baiyangdian Lake based on multiple biological groups]. / 应用多种生物类群评价白洋淀水环境质量变化.

Baiyangdian Lake is the largest shallow lake in the North China Plain. Due to the increases in upstream water consumption in recent decades, the amount of natural water entering the lake has decreased, resulting in a significant drop in the water level of Baiyangdian Lake. Severe eutrophication has occurred in Baiyangdian Lake owing to the discharge of domestic sewage around the sub-lakes. With the establishment of the Xiong'an New Area in 2017, the importance of environmental governance and protection of Baiyangdian Lake has been unprecedentedly increased. The implementation of ecological water supplement from upstream reservoirs and other basins has significantly increased water level of Baiyangdian Lake. Moreover, domestic sewage from surrounding rural areas was collected. In order to understand the current state of water quality in Baiyangdian Lake, and to evaluate the effects of the previous water replenishment and pollution control projects, we investigated water physicochemical variables and aquatic organisms of Baiyangdian Lake in August 2019. We evaluated water quality status of Baiyangdian Lake based on water quality, phytoplankton, zooplankton and macrozoobenthos, by comparing with the evaluation based on the survey data in 2010. In addition, submerged macrophytes were used to evaluate the water ecological status. The results showed that the water quality state of Baiyangdian Lake in 2019 was greatly improved compared with 2010. Among them, total phosphorus concentration decreased by 88.6%, total nitrogen concentration decreased by 83.9%, chlorophyll a concentration decreased by 47.8%, and the Seechi depth increased by 43.4%. The diversity of zooplankton and macrozoobenthos were significantly increased, the density of phytoplankton was significantly reduced, the dominant species of phytoplankton changed from a general highly eutrophic type to a eutrophic type, and the distribution of the clean-type submerged macrophytes was narrowed. The evaluation methods based on submerged macrophytes species and based on zooplankton diversity were not suitable for water quality evaluation in Baiyangdian Lake. In the early stage, the pollution source of Baiyangdian Lake was concentrated in the west, which led to lower water quality. Nowadays, due to the water replenishment from the west, north and south, the hydrodynamic conditions changed significantly. In the west, pollution control projects were carried out, and the spatial distribution of water quality in Baiyangdian Lake are showing a characteristics of homogenization.

A review on the methods of determining ecological thresholds.

The drastic changes or threshold phenomena of ecosystems in response to environmental changes are main research focuses in ecology. However, the difficulty in quantitative detection of ecological thresholds hinders the further research progress and application of this topic. Based on typical cases, we analzyed the driving-response mechanism of S-shaped curve type, subsidy-stress type, step type of the potential ecological thresholds. Seven methods to determine ecological thre-shold were summarized, including locally weighted scatterplot smoothing, piecewise regression, Gaussian model, change-point analyzer, regime shift detection, threshold indicator taxa analysis and system dynamics simulation model. The advantages, disadvantages and applicability of those methods were also addressed. This study could provide references for quantitative detection of ecological threshold.

Elevated O-GlcNAcylation Promotes Malignant Phenotypes of Hypopharyngeal Squamous Cell Carcinoma by Stabilizing Nrf2 through Regulation of the PI3K/Akt Pathway.

BACKGROUND AND PURPOSE: O-GlcNAcylation is a significant protein posttranslational modification with O-linked ß-N-acetylglucosamine (GlcNAc) for intracellular signaling. Elevated O-GlcNAcylation contributes to cell proliferation, cell migration, cell apoptosis and signal transduction in various cancers. However, the expression level and functional role of O-GlcNAcylation in Hypopharyngeal Squamous Cell Carcinoma (HSCC) is not clearly elucidated. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a master transcriptional factor that has been found to be aberrantly activated in HSCC. Here, we provide a molecular rationale between O-GlcNAcylation and Nrf2 in HSCC patients. METHODS: The protein levels of O-GlcNAcylation and Nrf2 in HSCC tissues were detected by immunohistochemistry technique and western blot analysis. Then, O-GlcNAcylation knockdown HSCC cells were applied in this study. Cell proliferation was detected by CCK8, colony-forming analysis, and cell cycle assays. Cell migration and invasion ability was evaluated by transwell assays. Cell apoptosis was measured by TUNEL analysis. RESULTS: O-GlcNAcylation was obviously up-regulated in HSCC tissues, which correlated with tumor size and lymph node metastasis. In addition, the protein level of Nrf2 was found to positively correlate with the expression of O-GlcNAcylation both in vivo and in vitro. Knockdown of O-GlcNAcylation significantly inhibited HSCC cell growth, suppressed cell migration, and promoted cell apoptosis, whereas overexpression of Nrf2 reversed these phenotypes. Mechanismly, the upregulation of O-GlcNAcylation promoted the phosphorylation of Akt, leading to the stabilization of Nrf2; this could be attenuated by inhibition of the PI3K/Akt signaling pathway. CONCLUSION: Here, we provide a molecular association between O-GlcNAcylation and Nrf2 in HSCC patients, thus providing valuable therapeutic targets for the disease.

[Research basis of ecological thresholds and regime shifts in China].

Non-linear changes widely occur in ecosystems, which manifest as sudden changes in system state with increasing pressure. To explain these changes, ecologists proposed the concepts of ecological threshold and regime shift, and continuously improved the theory and method system. Mechanistic and empirical studies further deepen our understanding for evolution mechanism of the complex system, which begun to be implemented into the environmental management. In recent decades, a large number of quantitative studies on stress-response in various types of ecosystems in China. Results from those studies are closely related to the theory paradigms of ecological threshold and regime shift in essence. Based on the "China Ecological Thresholds and Alternative Stable States Database", we screened and summarized the relevant ecological thresholds and explained the mechanisms underlying regime shift for 10 ecosystem types, including river, lake, wetland, forest, grassland, estuary and ocean, farmland, desert, city, and tundra. We linked case studies with theory paradigms of ecological threshold and regime shift with the aim to integrate multi-field scientific achievements and resources as the basis for ecosystem complexity research, and promote their application in ecological monitoring, ecological security early warning, and ecological standards innovation.

Transparent Conductive Flexible Trilayer Films for a Deicing Window and Self-Recover Bending Sensor Based on a Single-Walled Carbon Nanotube/Polyvinyl Butyral Interlayer.

A flexible transparent conductive film (TCF) is an important component in many modern smart devices. Recent TCF is always fabricated based on indium tin oxide (ITO). However, the drawbacks of ITO (e.g., brittle nature, high cost, and resource scarcity) and the complex preparation process of TCF limit the massive production and further application of TCF. Herein, a facile and low-cost method is proposed to prepare flexible TCF. Rolls of single-walled carbon nanotubes (SWCNTs)/polyvinyl butyral (PVB) interlayer film were first fabricated by the roll-to-roll (R2R) spraying method. Then, the interlayer film was laminated between polycarbonate (PC) films (0.1 mm in thickness) to fabricate a transparent (80% optical transmittance) but flexible trilayer film. Such a prepared trilayer film shows multifunctional applications. For example, on the one hand, high conductivity and uniform distribution of resistance ensure that it can work as a deicing window with good performance at a low voltage. On the other hand, its flexibility, rapid self-recovery, and stable response enable it to be used as a bending sensor, which shows remarkable stability, repeatability, and durability. This study provides a facile method to fabricate TCF based on commercial but low-cost materials, which is suitable for industrial production and wide practical applications.

Nicotinamide Overcomes Doxorubicin Resistance of Breast Cancer Cells through Deregulating SIRT1/Akt Pathway.

BACKGROUND AND PURPOSE: Breast cancer is one of the leading causes of cancer deaths in female worldwide. Doxorubicin represents the most common chemotherapy for breast cancer, whereas side effects and development of resistance impede its effect on chemotherapy. Nicotinamide (NAM), serves as the sirtuins' inhibitor, effectively suppressing various types of cancer. However, the effects of NAM on drug resistance of breast cancer are need to be fully investigated. METHODS: Breast cancer doxorubicin-resistant cells MCF-7/ADR and doxorubicin-sensitive cells MCF-7 were applied in this study. Cell proliferation was assessed by CCK8 and colony-forming assays. Cell migration was evaluated by scratch test and transwell assay while cell apoptosis was measured by TUNEL analysis. Expression levels of SIRT1, phosphate Akt (P-Akt, Ser-473) and Akt were measured using western blot analysis. The interrelation between SIRT1 and Akt was investigated by co-immunoprecipitation assay. RESULTS: Treatment of nicotinamide combined with doxorubicin effectively inhibited cell growth, suppressed cell migration, and promoted cell apoptosis of MCF7/ADR cells. Mechanistically, nicotinamide translocated SIRT1 from the cell nucleus to cytoplasm, dissociated the connection between SIRT1 and Akt, and consequently decreased expressions of SIRT1, and P-Akt, thereby inhibiting the growth of MCF7/ADR cells. CONCLUSIONS: Our results suggested that the value of nicotinamide is a potential therapeutic agent for breast cancer treatment through downregulating SIRT1/Akt pathway, leading to the valid management of breast cancer patients.

SIRT1 promotes formation of breast cancer through modulating Akt activity.

The silent information regulation factor 1 (sirtuin Type 1, SIRT1), as a kind of NAD+ dependent class III histone deacetylation enzyme, has been found to be involved in tumor proliferation, invasion, and metastasis. The roles of SIRTl in breast cancer is multifaceted depending on its substrate from upstream or downstream signaling pathway. In this study, we sought to make clear the regulating effects of SIRT1 in breast cancer cells, and to explore the underlying mechanisms through which SIRT1 regulates breast cancer. First, our results showed that SIRT1 was significantly up-regulated in breast cancer tissues and cells, which correlated with histological grade, tumor size, as well as lymph node metastasis. Then we established SIRT1-overexpressed and SIRT1- knockdown breast cancer cell lines to investigate the functions of SIRT1 in regulating colony formation, cell proliferation, cell cycle, cell apoptosis and migration. We found that overexpression of SIRT1 significantly promoted breast cancer growth both in vitro and in vivo, whereas knockdown of SIRT1 inhibited these phenotypes. Furthermore, SIRT1 was found to interact with Akt directly, consequently promoting the activity of Akt in breast cancer cells in vitro and positively correlating with expression of Akt, P-Akt, in breast cancer tissues in vivo. Down regulation the activity of Akt partially weakened the proliferative effect mediated by SIRT1. Taken together, our results demonstrated SIRT1's tumor promotion function and potential mechanisms in breast cancer, thus providing valuable therapeutic targets for breast cancer.

Expression of uPAR in human trophoblast and its role in trophoblast invasion.

Placental trophoblast cells differentiate into invasive trophoblasts or syncytiotrophoblasts. Abnormal trophoblast invasion results in pregnancy-associated disease and abortion. uPAR is a cell membrane-bound glycosylated protein, involved in physiological and pathological processes. However, uPAR expression in villi during threatened abortion and its role in trophoblast differentiation are unclear. We determined that, uPAR expression in the villi was reduced in threatened abortion patients than that in normal pregnancy. uPARsiRNA inhibited the potential for trophoblast migration and invasion in explants culture and HTR8/SVneo cells. It also enhanced forskolin-induced fusion of HTR8/SVneo cells. Overall, this study provides a possible reason for abortion.

Dynamic localisation of mature microRNAs in Human nucleoli is influenced by exogenous genetic materials.

Although microRNAs are commonly known to function as a component of RNA-induced silencing complexes in the cytoplasm, they have been detected in other organelles, notably the nucleus and the nucleolus, of mammalian cells. We have conducted a systematic search for miRNAs in HeLa cell nucleoli, and identified 11 abundant miRNAs with a high level of nucleolar accumulation. Through in situ hybridisation, we have localised these miRNAs, including miR-191 and miR-484, in the nucleolus of a diversity of human and rodent cell lines. The nucleolar association of these miRNAs is resistant to various cellular stresses, but highly sensitive to the presence of exogenous nucleic acids. Introduction of both single- and double-stranded DNA as well as double stranded RNA rapidly induce the redistribution of nucleolar miRNAs to the cytoplasm. A similar change in subcellular distribution is also observed in cells infected with the influenza A virus. The partition of miRNAs between the nucleolus and the cytoplasm is affected by Leptomycin B, suggesting a role of Exportin-1 in the intracellular shuttling of miRNAs. This study reveals a previously unknown aspect of miRNA biology, and suggests a possible link between these small noncoding RNAs and the cellular management of foreign genetic materials.

Cortical endogenic neural regeneration of adult rat after traumatic brain injury.

Focal and diffuse neuronal loss happened after traumatic brain injury (TBI). With little in the way of effective repair, recent interest has focused on endogenic neural progenitor cells (NPCs) as a potential method for regeneration. Whether endogenic neural regeneration happened in the cortex of adult rat after TBI remains to be determined. In this study, rats were divided into a sham group and a TBI group, and the rat model of medium TBI was induced by controlled cortical impact. Rats were injected with BrdU at 1 to 7 days post-injury (dpi) to allow identification of differentiated cells and sacrificed at 1, 3, 7, 14 and 28 dpi for immunofluorescence. Results showed nestin(+)/sox-2(+) NPCs and GFAP(+)/sox-2(+) radial glial (RG)-like cells emerged in peri-injured cortex at 1, 3, 7, 14 dpi and peaked at 3 dpi. The number of GFAP(+)/sox-2(+) cells was less than that of nestin(+)/sox-2(+) cells. Nestin(+)/sox-2(+) cells from posterior periventricle (pPV) immigrated into peri-injured cortex through corpus callosum (CC) were found. DCX(+)/BrdU(+) newborn immature neurons in peri-injured cortex were found only at 3, 7, 14 dpi. A few MAP-2(+)/BrdU(+) newborn neurons in peri-injured cortex were found only at 7 and 14 dpi. NeuN(+)/BrdU(+) mature neurons were not found in peri-injured cortex at 1, 3, 7, 14 and 28 dpi. While GFAP(+)/BrdU(+) astrocytes emerged in peri-injured cortex at 1, 3, 7, 14, 28 dpi and peaked at 7 dpi then kept in a stable state. In the corresponding time point, the percentage of GFAP(+)/BrdU(+) astrocytes in BrdU(+) cells was more than that of NPCs or newborn neurons. No CNP(+)/BrdU(+) oligodendrocytes were found in peri-injured cortex. These findings suggest that NPCs from pPV and reactive RG-like cells emerge in peri-injured cortex of adult rats after TBI. It can differentiate into immature neurons and astrocytes, but the former fail to grow up to mature neurons.

[Changes of peripheral blood chromosomal centromere aberration in patients with cytomegalovirus infection after anti-viral treatment].

OBJECTIVE: To study the changes of peripheral blood chromosomal centromere aberration in patents with cytomegalovirus (CMV) infection after anti-viral treatment. METHODS: Sixty-two patients with early spontaneous abortion and CMV infection analyzed for their peripheral blood chromosomal centromere using simultaneous silver staining before and after anti-viral treatment. RESULTS: The patients with CMV infection had high rate of centromere aberration, which was decreased significantly after anti-viral treatment (P<0.0001). CONCLUSION: CMV infection is a risk factor for peripheral blood chromosomal centrimere aberration. Anti-viral treatment can decrease the rate of centrimere aberration aberration. Detection of peripheral blood chromosomal centrimere aberration allows the assessment of the severity of infection and the condition after treatment.

Experimental study on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed.

A fixed-bed experimental reactor was employed to reveal the combustion characteristics in simulated municipal solid waste (MSW) beds. Temperature distributions, ignition front velocity, bed weight were measured during combustion and gas analysis was also performed for O2, CO2, CO, CxHy, NO, HCN. The moisture content in MSW was varied. For higher moisture content, the drying of material was finished much later and the ignition front temperatures, ignition front velocity and overall burning rate were found to drop. The average concentration of CO and CO2 from the bed was inversely proportional to the moisture level, and the highest concentrations of CO and CxHy were observed at middle level of investigated fuel moisture content. Measurements showed that NO and HCN emitted from the bed and reached the peaks simultaneously with the volatile matters, and the conversion ratio of fuel nitrogen to NO and average concentration of NO decreased with increasing moisture content.