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Bimetallic Assembled Silver Nanoparticles Impregnated in Aspergillus fumigatus Extract Damage the Bacterial Membrane Surface and Release Cellular Contents
No full textThe bactericidal effects of nanomaterials play an essential role in cytoplasmic leakage, leading to bacterial cell death. In this study, silver nanoparticles (AgNPs) were synthesized using a fungal extract of Aspergillus fumigatus (A. fumigatus). The physicochemical properties of the bare and myco-synthesized AgNPs (MS-AgNPs) were examined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). XRD revealed the crystalline structure of the prepared NPs. The FTIR spectrum of the MS-AgNPs revealed the presence of the stretching vibrations of hydroxyl (-OH) and carbonyl groups (C=O). The UV results showed absorption from 450 nm to 590 nm, confirming the synthesis of the AgNPs. SEM and TEM showed rough cubic shapes (spheres), 20-60 nm in size, while EDX confirmed the presence of 60% Ag in the sample. The MS-AgNPs revealed the highest antibacterial activity against Staphylococcus aureus, with a zone of inhibition of 18.21 +/- 2.1 mm, followed by Shigella dysenteriae and Salmonella typhi. The bimetallic-AgNPs played a vital role in cell membrane damage and the release of cellular contents, specifically nucleic acids and proteins. These results suggest that MS-AgNPs have promising antimicrobial capabilities and might be beneficial for an extensive array of biological applications
The Practical Experience of Zero Waste City Construction in Foshan City Condenses the Chinese Solution to the Sustainable Development Goals
No full textZero Waste City (ZWC) is an urban development model that minimizes the environmental impact of solid waste at the city level and is a specific practice of the Sustainable Development Goals (SDGs). This paper aims to summarize the key points for realizing the construction of ZWC and the SDGs and make suggestions for promoting the construction of ZWC and forming a Chinese solution for the SDGs. It takes Foshan City, one of the second batch of ZWC pilot projects, as a case study, analyzes the relationship between the construction of ZWC and sustainable urban development from the relevance of the ZWC index system in Foshan City and the SDGs, and analyzes the foundation and problems of its ZWC construction in adjusting the industrial structure and improving the protection system. We find that the concept of the ZWC index system in Foshan City and the SDGs are consistent in the objectives of solid waste, resource utilization, management, sustainability, and multi-stakeholder partnerships. The construction of ZWC in Foshan City is built through two intertwined paths by (1) adjusting the industrial structure of solid waste generation areas such as industrial waste, domestic waste, agricultural solid waste, and hazardous waste and promoting the refinement of the whole industrial chain in these fields and (2) improving the institutional, technical, market, regulatory and other protection systems in the solid waste generation fields. This paper condenses the construction of ZWC in Foshan as a Chinese solution for SDGs, providing a practical example of sustainable transformation for other manufacturing cities, with implications for both China and other manufacturing-oriented cities
Neural network guided interpolation for mapping canopy height of China's forests by integrating GEDI and ICESat-2 data
No full textSpatially continuous estimates of forest canopy height at national to global scales are critical for quantifying forest carbon storage, understanding forest ecosystem processes, and developing forest management and restoration policies to mitigate global climate change. Spaceborne light detection and ranging (lidar) platforms, especially the Global Ecosystem Dynamics Investigation (GEDI) and Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) Advanced Topographic Laser Altimeter System (ATLAS), can measure forest canopy height in discrete footprints globally. Their coverage provides a promising data source for national to global-scale forest canopy height estimates. However, previous studies usually used a regression-based approach to develop spatially continuous forest canopy height distribution through the aid of optical images, which cannot take full advantage of the dense spaceborne lidar footprints and may still suffer from the saturation effect of optical images. In this study, we developed a novel neural network guided interpolation (NNGI) method to map forest canopy height by fusing GEDI, ICESat-2 ATLAS, and Sentinel-2 images. To evaluate the performance of the proposed NNGI method, we generated a 30-m forest canopy height product of China for the year 2019. More than 140 km2 drone-lidar data were collected across the country to train and validate the NNGI method. The results showed that the average forest canopy height of China is 15.90 m with a standard deviation of 5.77 m. We evaluated the interpolated forest canopy height product of China by over 1,100,000 GEDI validation footprints (R2 = 0.55, RMSE = 5.32 m), about 33 km2 drone-lidar validation data (R2 = 0.58, RMSE = 4.93 m), and over 59,000 field plot measurements (R2 = 0.60, RMSE = 4.88 m). Benefiting from the interpolation-based mapping strategy, the resulting product had almost no saturation effect in areas with tall forest canopies. The high mapping accuracy demonstrates the feasibility of the proposed NNGI method for monitoring spatially continuous forest canopy height at national to global scales by integrating multi-platform spaceborne lidar data and optical images, enabling opportunities to provide more accurate quantification of terrestrial carbon storage and better understanding of forest ecosystem processes
Aboveground Biomass in China's Managed Grasslands and Their Responses to Environmental and Management Variations
No full textAboveground biomass (AGB) in managed grasslands can vary across a suite of environmental and management conditions; however, there lacks a quantitative assessment at the national scale of China. Although the potential effects of individual drivers (e.g., species, nutrient fertilization, and water management) have been examined in China's managed grasslands, no attempts have been made to comprehensively assess the effects of multiple variables on AGB. Using a meta-data analysis approach, we created a database composed of AGB and associated attributes of managed grasslands in China. The database was used to assess the responses of AGB to anthropogenic factors, in addition to a suite of natural variables including climate, soil, and topography. The average AGB in managed grasslands of China is approximately 630 g m(-2) of dry matter, ranging from 55 to 2172 g m(-2) (95% confidence interval). Medicago sativa is the most widely planted species in China's managed grasslands, followed by Elymus dahuricus and Bromus japonicus. The national average AGB of these three species was around 692, 530, and 856 g m(-2), respectively. For each species, AGB shows a large discrepancy across different places. In general, grassland AGB depends substantially on species, environments, and management practices. The dependence can be well described by a linear mixed-effects regression in which a series of biotic and abiotic factors are used as predictors. We highlight that establishing managed grassland can potentially contribute to not only AGB enhancement, but also grassland restoration on degraded natural grasslands
Seed Traits Research Is on the Rise: A Bibliometric Analysis from 1991-2020
No full textSeed traits (ST) influence seedling establishment, population dynamics, community composition and ecosystem function and reflect the adaptability of plants and the environmental conditions they experienced. There has been a historical and global accumulation of studies on ST, but with few pertaining to visual and quantitative analyses. To understand the trends in the field of ST research in the past 30 years, we conducted a bibliometric analysis based on the Science Citation Index-Expanded (SCI-E) database. The analysis provided annual publications, time trends for keywords, the most productive journals, authors, institutions and countries, and a comprehensive overview of the ST field. Our results showed that in the past 30 years, the number of publications in ST research has increased at an average annual growth rate of 9.1%, while the average number of citations per paper per year showed a rapid increase-slow increase-decrease trend. Keyword analysis showed that germination was the most popular research section. Crop Science ranked first among the top journals and Theoretical and Applied Genetics had greater influence in this area and more citations than other journals. The 10 most productive institutions were mostly located in the United States, China and Australia. Furthermore, the three countries also had the largest number of publications and citations. Our analysis showed that the research interests in ST have evolved from genetics and agricultural science to ecological research over the last thirty years; as more fields embrace ST research, there are opportunities for international and interdisciplinary collaborations, cooperative institutions and new advances in the field
Loess Landslide Detection Using Object Detection Algorithms in Northwest China
No full textRegional landslide identification is important for the risk management of landslide hazards. The traditional methods of regional landslide identification were mainly conducted by a human being. In previous studies, automatic landslide recognition mainly focused on new landslides distinct from the environment induced by rainfall or earthquake, using the image classification method and semantic segmentation method of deep learning. However, there is a lack of research on the automatic recognition of old loess landslides, which are difficult to distinguish from the environment. Therefore, this study uses the object detection method of deep learning to identify old loess landslides with Google Earth images. At first, a database of loess historical landslide samples was established for deep learning based on Google Earth images. A total of 6111 landslides were interpreted in three landslide areas in Gansu Province, China. Second, three object detection algorithms including the one-stage algorithm RetinaNet and YOLO v3 and the two-stage algorithm Mask R-CNN, were chosen for automatic landslide identification. Mask R-CNN achieved the greatest accuracy, with an AP of 18.9% and F1-score of 55.31%. Among the three landslide areas, the order of identification accuracy from high to low was Site 1, Site 2, and Site 3, with the F1-scores of 62.05%, 61.04% and 50.88%, respectively, which were positively related to their recognition difficulty. The research results proved that the object detection method can be employed for the automatic identification of loess landslides based on Google Earth images
Melatonin alleviates aluminum-induced growth inhibition by modulating carbon and nitrogen metabolism, and reestablishing redox homeostasis in Zea mays L.
No full textMelatonin, a regulatory molecule, performs pleiotropic functions in plants, including aluminum (Al) stress mitigation. Here, we conducted transcriptomic and physiological analyses to identify metabolic processes associated with the alleviated Al-induced growth inhibition of the melatonin-treated (MT) maize (Zea mays L.) seedlings. Melatonin decreased Al concentration in maize roots and leaves under Al stress. Al stress reduced the total dry weight (DW) by 41.2% after 7 days of treatment. By contrast, the total DW was decreased by only 19.4% in MT plants. According to RNA-Seq, enzyme activity, and metabolite content data, MT plants exhibited a higher level of relatively stable carbon and nitrogen metabolism than non-treated (NT) plants. Under Al stress, MT plants showed higher photosynthetic rate and sucrose content by 29.9% and 20.5% than NT plants, respectively. Similarly, the nitrate reductase activity and protein content of MT plants were 34.0% and 15.0% higher than those of NT plants, respectively. Furthermore, exogenous supply of melatonin mitigated Al-induced oxidative stress. Overall, our results suggest that melatonin alleviates aluminum-induced growth inhibition through modulating carbon and nitrogen metabolism, and reestablishing redox homeostasis in maize. Graphical Abstarc
Impact of Litsea cubeba inter-row cover on the structure of bacterial community in the tea plantation
No full textPurpose: The application of bio-control plants in the agricultural processes is one of the effective ways to solve the traditional agricultural synthetic pesticide residues. This study will investigate the effect of bio-control plant Litsea cubeba branch inter-row cover on soil bacterial community, soil-enriched metabolites, and soil mineral nutrition in tea plantation, which will provide a basis for the use of bio-control plant in agroecological farming systems. Methods: The fruit-bearing (F-Pr) and vegetative (F-Ab) branches of Litsea cubeba were inter-row covered (the use of plants for partial coverage of soil between the rows) in the tea plantation. And we determined the soil microbial community, soil mineral nutriment, and soil-enriched metabolites composition with the methods of 16S rRNA gene sequencing, inductively coupled plasma-atomic emission spectroscopy (ICP-AEC), inductively coupled plasma-optical emission spectrometry (ICP-OES), and gas chromatography-mass spectrometry (GS-MS). We also predict the function of soil bacteria with the Tax4Fun software. Results: Litsea cubeba inter-row cover modified the soil microbial structure and diversity; Litsea cubeba inter-row cover significantly decreased the relative abundance of Acidobacteria, Chloroflexi, and Planctomycetes while increased the relative abundance of Proteobacteria. Litsea cubeba inter-row cover significantly antagonized the plant pathogen community, and its OTUs number decreased from 907 +/- 81 in the control to 337 +/- 25 in F-Pr treatment; compared with F-Pr treatment, F-Ab treatment had weaker effect on the abundance of nutrition metabolism and transport, carbohydrate utilization, and nitrate reduction A. The aluminum element in the F-Pr treatment was significantly reduced, while phosphorus was increased. The soil-enriched metabolites of F-Pr treatment contained some antibacterial substance, including 14.2 +/- 3.32% citronellol, 10.38 +/- 4.79% alpha-terpineol, and 8.25 +/- 2.62% (+)-2-bornanone, which was the main environment factor that affects the soil bacterial structure and diversity. Conclusion: Litsea cubeba inter-row cover significantly affected bacterial structure and diversity, slightly increased the soil pH, and improved soil aluminum and phosphorus status; soil-enriched metabolites were the major environment factor affecting soil bacterial community and should be considered in the application of bio-control plants; Litsea cubeba vegetative branch inter-row cover will be a feasible measure for integrated pest management in tea plantation
Identification of qGL3.5, a Novel Locus Controlling Grain Length in Rice Through Bulked Segregant Analysis and Fine Mapping
No full textGrain length (GL) directly affects the yield and quality of rice. Very few cloned GL-related genes are applied in production because their yield-increasing effects are not obvious, and the overall regulatory networks underlying the associated processes remain poorly understood. DNA samples from two bulk DNA pools (L-pool and S-pool) and their parents (KJ01 and Huaye 3) were subjected to high-throughput sequencing. Using bulked segregant analysis (BSA), qGL3.5 was mapped to a 0.34-Mb hotspot region on chromosome 3 that contains 37 genes related to various traits. Then, qGL3.5 was mapped to the genomic interval between the flanking markers M2 and M3 using 2786 BC4F2 individuals. Because the region from B5 to B6 was not the associated region under BSA-seq analysis, qGL3.5 was narrowed down to the interval between B6 and M3, which spanned 24.0-kb. Of all 37 genes with non-synonymous single-nucleotide polymorphisms (SNPs) between KJ01 and Huaye 3 based on BSA-seq analysis, only one complete annotated gene, ORF18 (Gene ID: LOC_Os03g42790.1) was found. ORF18 encodes an IBR-RING zinc-finger-related protein, with one really interesting new gene (RING) and two in between ring finger (IBR) domains. The knockout of ORF18 derived from Huaye 3 using clustered, regularly interspaced, short palindromic repeat (CRISPR)/CRISPR-associated 9 (Cas9) editing technology increased the GL of the mutant by approximately 2.2 mm. The novel locus qGL3.5 negatively regulated GL by promoting elongation of the longitudinal cell of the grain outer glume. These results provide a new genetic resource for rice grain shape breeding and a starting point for the functional characterization of the wild rice GL gene
Nitrogen enrichment buffers phosphorus limitation by mobilizing mineral-bound soil phosphorus in grasslands
No full textPhosphorus (P) limitation is expected to increase due to nitrogen (N)-induced terrestrial eutrophication, although most soils contain large P pools immobilized in minerals (P-i) and organic matter (P-o). Here we assessed whether transformations of these P pools could increase plant available pools alleviating P limitation under enhanced N availability. The mechanisms underlying these possible transformations were explored by combining results from a 10-year field N addition experiment and a 3700-km transect covering wide ranges in soil pH, soil N, aridity, leaching, and weathering that could affect soil P status in grasslands. Nitrogen addition promoted the dissolution of immobile P-i (mainly Ca-bound recalcitrant P) to more available forms of P-i (including Al- and Fe-bound P fractions and Olsen P) by decreasing soil pH from 7.6 to 4.7, but did not affect P-o. Soil total P declined by 10% from 385 +/- 6.8 to 346 +/- 9.5 mg kg(-1), whereas available P increased by 546% from 3.5 +/- 0.3 to 22.6 +/- 2.4 mg kg(-1) after the 10-year N addition, associated with an increase in P-i mobilization, plant uptake, and leaching. Similar to the N addition experiment, the drop in soil pH from 7.5 to 5.6 and increase in soil N concentration along the grassland transect were associated with an increased ratio between relatively mobile P-i and immobile P-i. Our results provide a new mechanistic understanding of the important role of soil P-i mobilization in maintaining plant P supply and accelerating biogeochemical P cycles under anthropogenic N enrichment. This mobilization process temporarily buffers ecosystem P limitation or even causes P eutrophication, but will extensively deplete soil P pools in the long run