Restoration of degraded grassland is an essential issue which has been widely concerned but not effectively resolved. Fencing and nitrogen fertilization are common and efficient restoration practices. However, there are still controversy on the effectiveness and duration of fencing and nitrogen fertilization on the restoration of degraded grassland. To estimate the effects of fencing and nitrogen fertilization on the community above-ground net primary productivity (ANPP) and stability, and explore the underlying mechanism, an 18-year (from 2003 to 2020) fencing and nitrogen fertilization (8 g N m−2 year−1) field experiment was conducted on a degraded temperate steppe in Inner Mongolia. Community ANPP and species richness were measured at the peak of plant biomass in growing season (mid-August) from 2004 to 2020. Temporal stability of community ANPP were calculated to estimate the community stability under different restoration managements. We found that both fencing and nitrogen fertilization can significantly increase the ANPP. Nevertheless, ANPP tended to keep stable rather than continuously increase with the extension of restoration duration. Long-term fencing and nitrogen fertilization significantly reduced the stability of ANPP in early stage of restoration (2004–2010), but had no significant effect on the stability of ANPP in later stage (2011–2020). Moreover, the stability of ANPP maintained stable with extension of restoration duration. Furthermore, we found that the biological factors that regulate the community stability were similar between the two restoration measures. Specifically, the stability of ANPP was regulated by species asynchrony in early phase, while, it was mediated by both species asynchrony and dominant species stability in later phase. Overall, from the perspective of community ANPP, the degraded steppe reached optimal status after approximately seven years of fencing and nitrogen fertilization, appropriate utilization after seven years' restoration may be conducive to maintain ANPP and the stability of ANPP. This study provided valuable information for better restoring and managing the degraded temperate steppes.
Summary Root anatomy plays important roles in the control of leaf water relations. However, few studies have evaluated whether and how anatomical traits of absorptive roots influence leaf physiology of herbaceous species in a temperate grassland. We measured absorptive root anatomical traits and leaf physiological traits of 15 herbaceous species in a temperate steppe and monitored their responses to increased precipitation in a field stimulating experiment. Root anatomical and leaf physiological traits differed among monocotyledonous grasses, monocotyledonous liliaceous species and dicotyledonous forbs. The species with higher stele: root diameter, lower root diameter and cortex thickness exhibited higher transpiration rates and stomatal conductance, but lower intrinsic water‐use efficiency. Increased precipitation enhanced transpiration and stomatal conductance of forbs and lilies, but it enhanced photosynthesis in lilies exclusively. The sensitive response of lilies to precipitation may be related to their large root diameter and cortex thickness. In summary, we observed distinct differences in anatomical traits of absorptive roots among plant groups in temperate steppes. These differences drove variations in leaf physiological traits and their diverse responses to precipitation change. These findings highlight the important roles of root anatomical traits in driving leaf‐level physiological processes in temperate grasslands.
Abstract Aim We investigate the evaluation methods of teaching oral implant clinical courses and estimate the effectiveness of a virtual simulation platform. Methods Eighty second- and third-year undergraduates in Lanzhou University were recruited and randomized to either three experimental groups or one control group. The subjects undertook theoretical examinations to test their basic level of knowledge after training in similarly unified knowledge courses. Each student group then participated in an eight-hour operating training session. An operation test on pig mandible was conducted, followed by a second theoretical examination. The assessment consists of three distinct parts: a subjective operating score by a clinical senior teacher, an implant accuracy analysis in cone-beam computed tomography (angular, apical, and entrance deviation), and comparison of the two theoretical examinations. Finally, students completed a questionnaire gauging their understanding of the virtual simulation. Results There was no significant difference between the four groups in first theoretical examination (P>0.05); the second theoretical scores of the V-J and J-V group (62.90±3.70, 60.05±2.73) were significantly higher than the first time (57.05±3.92, P < 0.05), while no difference between the V(57.10±3.66) and J (56.89±2.67) groups was found. Thus, the combination of V-J was effective in improving students’ theoretical scores. The V-J and J-V groups had higher scores on operation (73.98±4.58; 71.85±4.67) and showed better implant precision.Conclusion Virtual simulation education, especially with a jaw simulation model, could improve students’ implantology achievements and training. We found that the V-J group performed better than the J-V group in oral implant teaching.
Rationale Aged arteries are characterized by attenuated vasodilator and enhanced vasoconstrictor responses, which contribute to endothelial dysfunction in vascular diseases such as arterial hypertension, atherosclerosis and heart failure. SIRT1 is a longevity regulator exerting protective functions against vascular ageing, although the underlying mechanisms remain largely unknown. Objective The present study was designed to elucidate the signaling pathways involved in endothelial SIRT1‐mediated vasodilator responses during arterial aging. In particular, the contributions of nitric oxide (NO), endothelial NO synthase (eNOS), cyclooxygenase (COX) and/or soluble guanylyl cyclase (sGC) were examined. Methods and Results Wild type (WT) or endothelial NO synthase knockout (eKO) mice were cross‐bred with those overexpressing human SIRT1 selectively in the vascular endothelium (EC‐SIRT1). Arteries were collected from the four groups of mice (WT, EC‐SIRT1, eKO and eKO‐SIRT1) to measure isometric relaxations/contractions in response to various pharmacological agents. In arteries of WT animals, decreased NO bioavailability, hyper‐activated COX signaling and downregulated sGC expression/activity collectively contributed to the increased vasoconstrictor and decreased vasodilator responses during ageing. Arteries of EC‐SIRT1 mice were protected from ageing‐induced alterations in smooth muscle relaxation/contraction and the vasodilator responses. Overexpression of endothelial SIRT1 did not block the reduction in NO bioavailability, but attenuated the hyper‐activation of COX‐2; the latter effect resulted in an inhibition of endothelium‐dependent contractions in arteries of EC‐SIRT1 and eKO‐SIRT1 mice. The sGC β1 subunit was significantly upregulated by endothelial overexpression of SIRT1 and the expression remained higher in arteries of old EC‐SIRT1 than those of age‐matched WT mice. Disruption of endothelial SIRT1 function downregulated sGC β1 expression. Moreover, overexpression of endothelial SIRT1 enhanced the relaxations to NO‐independent sGC stimulators in arteries of EC‐SIRT1 and eKO‐SIRT1 mice. Conclusions Endothelial SIRT1 prevents age‐induced impairment of vasodilatation largely by inhibiting COX‐2‐mediated endothelium‐dependent contractions and enhancing sGC‐mediated smooth muscle relaxation, independently of eNOS and NO signaling. Support or Funding Information This work was financially supported by the grants from Research Grant Council of Hong Kong (780613M and 17121714), Hong Kong Health and Medical Research Fund (13142651 and 13142641), Collaborative Research Fund of Hong Kong (C7055‐14G) and the National Basic Research Program of China (973 Program 2015CB553603). This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
This paper reports a case of ipsilateral inferior alveolar nerve paresthesia because of gutta-percha overfilling of the left mandibular second molar into the surrounding bone marrow cavity and mandibular nerve canal, but the patient refused surgical debridement and nerve decompression. This patient was being followed-up radiologically CBCT up to five years for observing the dynamic changes of the overfilled gutta-percha.
Selective laser melting (SLM) is widely used in lattice structure manufacturing. ARCH lattice structure is named ARCH because the center line of ARCH strut is arched; compared with other structures, arch can afford bigger pressure. Herein, the ARCH lattice structures are analyzed by finite element analysis, and the stress distribution of the ARCH lattice structures is obtained. The quasistatic compression experiment is conducted on the ARCH lattice structure samples. The mechanical properties and energy absorption capability of ARCH lattice structures with different relative densities fabricated by SLM are experimentally researched. The results show that, compared with other lattice structures, ARCH lattice structures have superior mechanical properties and energy absorption capability. The relative density has a great influence on the mechanical properties and energy absorption capability of ARCH lattice structures. The Gibson–Ashby equation is also established to estimate the mechanical properties and energy absorption capability of the lattice structures with different relative densities.
// Bo Bai 1,3,* , Andy W.C. Man 1,* , Kangmin Yang 1 , Yumeng Guo 1 , Cheng Xu 1 , Hung-Fat Tse 2 , Weiping Han 3 , Maria Bloksgaard 4 , Jo G.R. De Mey 4 , Paul M. Vanhoutte 1 , Aimin Xu 1,2 and Yu Wang 1 1 State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China 2 Department of Medicine, The University of Hong Kong, Hong Kong, China 3 Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), Singapore 4 Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark * Co-first authors Correspondence to: Yu Wang, email: // Keywords : hypertension, blood vessel remodeling, endothelial senescence, SIRT1, LKB1, Gerotarget Received : February 29, 2016 Accepted : May 23, 2016 Published : May 29, 2016 Abstract Aims-SIRT1 exerts potent activity against cellular senescence and vascular ageing. By decreasing LKB1 protein levels, it promotes the survival and regeneration of endothelial cells. The present study aims to investigate the molecular mechanisms underlying SIRT1-mediated LKB1 degradation for the prevention of vascular ageing. Methods and Results-Co-immunoprecipitation assay demonstrated that SIRT1, via its amino-terminus, binds to the DOC domain of HERC2 [HECT and RLD domain containing E3 ubiquitin protein ligase 2], which then ubiquitinates LKB1 in the nuclear compartment of endothelial cells. Site-directed mutagenesis revealed that acetylation at lysine (K) 64 of LKB1 triggers the formation of SIRT1/HERC2/LKB1 protein complex and subsequent proteasomal degradation. In vitro cellular studies suggested that accumulation of acetylated LKB1 in the nucleus leads to endothelial activation, in turn stimulating the proliferation of vascular smooth muscle cells and the production of extracellular matrix proteins. Chromatin immunoprecipitation quantitative PCR confirmed that acetylated LKB1 interacts with and activates TGFβ1 promoter, which is inhibited by SIRT1. Knocking down either SIRT1 or HERC2 results in an increased association of LKB1 with the positive regulatory elements of TGFβ1 promoter. In mice without endothelial nitric oxide synthase, selective overexpression of human SIRT1 in endothelium prevents hypertension and age-related adverse arterial remodeling. Lentiviral-mediated knockdown of HERC2 abolishes the beneficial effects of endothelial SIRT1 on both arterial remodeling and arterial blood pressure control. Conclusion-By downregulating acetylated LKB1 protein via HERC2, SIRT1 fine-tunes the crosstalk between endothelial and vascular smooth muscle cells to prevent adverse arterial remodeling and maintain vascular homeostasis.
The sensitive and accurate determination of glyphosate (Glyp) is urgently demanded because it is closely correlated with human health and environmental safety. In this work, we proposed a sensitive and convenient colorimetric assay by employing copper ion peroxidases for the detection of Glyp in the environment. Free Cu(II) ions displayed high peroxidase activity and can catalytically oxidize the colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxTMB, resulting in an obviously visible discoloration reaction. Once the Glyp is added, the ability of copper ions to mimic peroxidase can be largely suppressed because of the generation of Glyp-Cu
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