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  • MDPI AG  (12)
  • 1
    Online Resource
    Online Resource
    The Impacts of Hydrology and Climate on Hydrological Connectivity in a Complex River–Lake Floodplain System Based on High Spatiotemporal Resolution Images
    MDPI AG ; 2022
    In:  Water Vol. 14, No. 12 ( 2022-06-07), p. 1836-
    Details
    In: Water, MDPI AG, Vol. 14, No. 12 ( 2022-06-07), p. 1836-
    Abstract: The drivers that determine the hydrological connectivity (HC) are complex and interrelated, and disentangling this complexity will improve the administration of the river–lake interconnection system. Dongting Lake, as a typical river–lake interconnected system, is freely connected with the Yangtze River and their HC plays a major role in keeping the system healthy. Climate, hydrology, and anthropogenic activities are associated with the HC. In this study, hydrological drivers were divided into the total flow of three inlets (T-flow) and the total flow of four tributaries (F-flow). To elucidate the HC of the Dongting Lake, HC was calculated by geostatistical methods in association with Sentinel-2 remote sensing images. Then, the structural equation model (SEM) was used to quantify the impacts of hydrology (F-flow, and T-flow) and meteorology (precipitation, evaporation, and temperature) on HC. The geostatistical analysis results demonstrated that the HC showed apparent seasonal change. For East and West Dongting Lake, the dominant element was north–south hydrological connectivity (N–S HC), and the restricted was west–east hydrological connectivity (W-E HC), but the dominant element was E–W HC and the restricted was N–S HC in South Dongting Lake. The results of SEM showed that N–S HC was mainly explained by T-flow (r = 0.49, p 〈 0.001) and F-flow (r = 0.28, p 〈 0.05). T-flow, temperature (r = 0.33, p 〈 0.05), and F-flow explained E–W HC. The finding of this work supports the management of both the Dongting Lake floodplain and other similar river–lake floodplain systems.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    URL: Article
    DOI: 10.3390/w14121836
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2521238-2
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  • 2
    Online Resource
    Online Resource
    Crushing Behaviors and Energy Absorption Evaluation Methods of Hexagonal Steel Tubular Columns with Triangular Cells
    MDPI AG ; 2022
    In:  Materials Vol. 15, No. 11 ( 2022-05-31), p. 3910-
    Details
    In: Materials, MDPI AG, Vol. 15, No. 11 ( 2022-05-31), p. 3910-
    Abstract: Under axial compression, multi-cell tubes are considered more effective than single-cell tubes. Regular hexagonal multi-cell tubes (HMT) were designed, tested, and analyzed by finite element modeling (FEM). The crushing mechanism of the HMT was revealed by compression testing and FEM. Experiments and FEM revealed that the mean crushing force of the HMT can be increased by 14% by adopting multi-cell topology, which shortens the folding wavelength and enables HMT progressive crushing. Thus, the HMT is more efficient in energy absorption compared with the conventional regular hexagonal thin-walled tube (HST). More triangular cells result in HMTs with much greater mean crushing force and specific energy absorption. Three evaluation methods were proposed and discussed to determine the effective crushing distance. A plastic model established according to classical simplified super-folding elements was shown to consistently predict the mean crushing force of the HMTs.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma15113910
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2487261-1
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  • 3
    Online Resource
    Online Resource
    The Flavonoid Biosynthesis Network in Plants
    MDPI AG ; 2021
    In:  International Journal of Molecular Sciences Vol. 22, No. 23 ( 2021-11-26), p. 12824-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 22, No. 23 ( 2021-11-26), p. 12824-
    Abstract: Flavonoids are an important class of secondary metabolites widely found in plants, contributing to plant growth and development and having prominent applications in food and medicine. The biosynthesis of flavonoids has long been the focus of intense research in plant biology. Flavonoids are derived from the phenylpropanoid metabolic pathway, and have a basic structure that comprises a C15 benzene ring structure of C6-C3-C6. Over recent decades, a considerable number of studies have been directed at elucidating the mechanisms involved in flavonoid biosynthesis in plants. In this review, we systematically summarize the flavonoid biosynthetic pathway. We further assemble an exhaustive map of flavonoid biosynthesis in plants comprising eight branches (stilbene, aurone, flavone, isoflavone, flavonol, phlobaphene, proanthocyanidin, and anthocyanin biosynthesis) and four important intermediate metabolites (chalcone, flavanone, dihydroflavonol, and leucoanthocyanidin). This review affords a comprehensive overview of the current knowledge regarding flavonoid biosynthesis, and provides the theoretical basis for further elucidating the pathways involved in the biosynthesis of flavonoids, which will aid in better understanding their functions and potential uses.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms222312824
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Biochemical and Structural Insights into a Thiamine Diphosphate-Dependent α-Ketoglutarate Decarboxylase from Cyanobacterium Microcystis aeruginosa NIES-843
    MDPI AG ; 2023
    In:  International Journal of Molecular Sciences Vol. 24, No. 15 ( 2023-07-30), p. 12198-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 24, No. 15 ( 2023-07-30), p. 12198-
    Abstract: α-Ketoglutarate decarboxylase is a crucial enzyme in the tricarboxylic acid cycle of cyanobacteria, catalyzing the non-oxidative decarboxylation of α-ketoglutarate to produce succinate semialdehyde and CO2. The decarboxylation process is reliant on the cofactor of thiamine diphosphate. However, this enzyme’s biochemical and structural properties have not been well characterized. In this work, two α-ketoglutarate decarboxylases encoded by MAE_06010 and MiAbw_01735 genes from Microcystis aeruginosa NIES-843 (MaKGD) and NIES-4325 (MiKGD), respectively, were overexpressed and purified by using an Escherichia coli expression system. It was found that MaKGD exhibited 9.2-fold higher catalytic efficiency than MiKGD, which may be attributed to the absence of glutamate decarboxylase in Microcystis aeruginosa NIES-843. Further biochemical investigation of MaKGD demonstrated that it displayed optimum activity at pH 6.5–7.0 and was most activated by Mg2+. Additionally, MaKGD showed substrate specificity towards α-ketoglutarate. Structural modeling and autodocking results revealed that the active site of MaKGD contained a distinct binding pocket where α-ketoglutarate and thiamine diphosphate interacted with specific amino acid residues via hydrophobic interactions, hydrogen bonds and salt bridges. Furthermore, the mutagenesis study provided strong evidence supporting the importance of certain residues in the catalysis of MaKGD. These findings provide new insights into the structure-function relationships of α-ketoglutarate decarboxylases from cyanobacteria.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms241512198
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Comparative Transcriptome and Pigment Analyses Reveal Changes in Gene Expression Associated with Flavonol Metabolism in Yellow Camellia
    MDPI AG ; 2022
    In:  Forests Vol. 13, No. 7 ( 2022-07-12), p. 1094-
    Details
    In: Forests, MDPI AG, Vol. 13, No. 7 ( 2022-07-12), p. 1094-
    Abstract: The accumulation of various pigments leads to the formation of different flower colors in plants. However, the regulation mechanism of yellow flower formation and flower color differences between Camellia nitidssima C.W.Chi (CN) and its hybrids C. ‘Zhenghuangqi’ (ZHQ), C. ‘Huangxuanlv’ (HXL), and C. ‘Xinshiji’ (XSJ), remains largely unknown. Here, we showed that the content of two flavonols, quercetin-7-O-glucoside (Qu7G) and quercetin-3-O-glucoside (Qu3G), was positively correlated with the yellow degree of petals in CN and its three hybrids. Additionally, we performed a comparative transcriptomic analysis of petals of the four yellow camellia plants, which revealed 322 common upregulated and 866 common downregulated DEGs (differentially expressed genes) in the CN vs. ZHQ, CN vs. HXL, and CN vs. XSJ comparison groups. Their regulatory pathway analysis showed that flavonol biosynthesis genes (FLSs and GTs) and transcriptional regulatory genes MYBs were all expressed higher in CN than its three hybrids, which corresponded to differences in the flavonol content among the four yellow camellias. Further, two ethylene synthesis genes (ACSs, ACO) and three ethylene signaling genes (EIN2s, EIN3, ERFs) were all upregulated in the yellow petals of CN. In conclusion, the expression of flavonol-related genes and flavonols (Qu7G and Qu3G) accumulation could play a key role in the formation of yellow flowers in camellia, and the ethylene pathway might be involved in the regulation of yellow flower formation of camellias. This work describes the possible regulatory pathway of yellow camellia, thereby laying a foundation for future verification of genes linked to flower coloring and the breeding of yellow camellia.
    Type of Medium: Online Resource
    ISSN: 1999-4907
    URL: Article
    DOI: 10.3390/f13071094
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2527081-3
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  • 6
    Online Resource
    Online Resource
    Identification of Chalcone Isomerase Family Genes and Roles of CnCHI4 in Flavonoid Metabolism in Camellia nitidissima
    MDPI AG ; 2022
    In:  Biomolecules Vol. 13, No. 1 ( 2022-12-26), p. 41-
    Details
    In: Biomolecules, MDPI AG, Vol. 13, No. 1 ( 2022-12-26), p. 41-
    Abstract: Camellia nitidissima is a woody plant with high ornamental value, and its golden-yellow flowers are rich in a variety of bioactive substances, especially flavonoids, that are beneficial to human health. Chalcone isomerases (CHIs) are key enzymes in the flavonoid biosynthesis pathway; however, there is a scarcity of information regarding the CHI family genes of C. nitidissima. In this study, seven CHI genes of C. nitidissima were identified and divided into three subfamilies by phylogenetic analysis. The results of multiple sequence alignment revealed that, unlike CnCHI1/5/6/7, CnCHI2/3/4 are bona fide CHIs that contain all the active site and critical catalytic residues. Analysis of the expression patterns of CnCHIs and the total flavonoid content of the flowers at different developmental stages revealed that CnCHI4 might play an essential role in the flavonoid biosynthesis pathway of C. nitidissima. CnCHI4 overexpression significantly increased flavonoid production in Nicotiana tabacum and C. nitidissima. The results of the dual-luciferase reporter assay and yeast one-hybrid system revealed that CnMYB7 was the key transcription factor that governed the transcription of CnCHI4. The study provides a comprehensive understanding of the CHI family genes of C. nitidissima and performed a preliminary analysis of their functions and regulatory mechanisms.
    Type of Medium: Online Resource
    ISSN: 2218-273X
    URL: Article
    DOI: 10.3390/biom13010041
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2701262-1
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  • 7
    Online Resource
    Online Resource
    Increased Inequalities in Health Resource and Access to Health Care in Rural China
    MDPI AG ; 2018
    In:  International Journal of Environmental Research and Public Health Vol. 16, No. 1 ( 2018-12-25), p. 49-
    Details
    In: International Journal of Environmental Research and Public Health, MDPI AG, Vol. 16, No. 1 ( 2018-12-25), p. 49-
    Abstract: Both health resources and access to these resources increased after China’s health care reform launched in 2009. However, it is not clear if the inequalities were reduced within rural China, which was one of the main targets in the reform. This study aims to examine the changes in inequalities in health resources and access following the reform. Data came from the routine report of rural counties in every other year from 2008 to 2014. Health professionals and hospital beds per 1000 population were used for measuring health resources, and the hospitalization rate was used for access. Descriptive analysis and the fixed effect model were used in this study. Health resources and access increased by about 50% between 2008 and 2014 in rural China. The counties in richer quintiles got more health resources and hospitalizations. As for health professionals, the absolute differences between the richer and the poorest quintile were significantly enlarging in 2014 when compared to 2008. Regarding the hospitalization rate, the differences between the richest and the poorest quintile showed no significant change after 2012. In sum, absolute inequalities of health resources were increased, while that of health utilization kept constant following China’s health care reform. The reform needs to continually recruit qualified health workers and appropriately allocate health infrastructures to strengthen the capacity of the health care system in the impoverished areas.
    Type of Medium: Online Resource
    ISSN: 1660-4601
    URL: Article
    DOI: 10.3390/ijerph16010049
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2175195-X
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  • 8
    Online Resource
    Online Resource
    Design of a Matching Network for a High-Sensitivity Broadband Magnetic Resonance Sounding Coil Sensor
    MDPI AG ; 2017
    In:  Sensors Vol. 17, No. 11 ( 2017-10-27), p. 2463-
    Details
    In: Sensors, MDPI AG, Vol. 17, No. 11 ( 2017-10-27), p. 2463-
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s17112463
    Language: English
    Publisher: MDPI AG
    Publication Date: 2017
    detail.hit.zdb_id: 2052857-7
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  • 9
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    Transcriptome Analysis Reveals the Molecular Mechanisms Associated with Flower Color Formation in Camellia japonica ‘Joy Kendrick’
    MDPI AG ; 2022
    In:  Forests Vol. 14, No. 1 ( 2022-12-30), p. 69-
    Details
    In: Forests, MDPI AG, Vol. 14, No. 1 ( 2022-12-30), p. 69-
    Abstract: Camellia japonica is a woody flower with high ornamental and economic value used for landscaping and as a pot plant. Floral colors are among the most important ornamental traits of flower plants, particularly multicolored flowers. The C. japonica cultivar ‘Joy Kendrick’ has multicolored flowers; the corolla is pink with darker red stripes, but the molecular mechanism underlying this trait is unknown. Here, pigment analysis showed that there are more anthocyanins accumulate in red petal regions than in pink areas, which may be key to formation of red stripes. Furthermore, transcriptome analysis revealed that anthocyanin biosynthesis, modification, and transporter genes are highly expressed in red stripes, consistent with the observed anthocyanin accumulation. In addition, many plant hormone signal transduction genes, particularly auxin, may contribute to the regulation of red stripe formation. This study provides broad insights into pigment accumulation and the regulatory mechanisms underlying floral color formation in C. japonica, and lays a foundation for breeding new C. japonica varieties.
    Type of Medium: Online Resource
    ISSN: 1999-4907
    URL: Article
    DOI: 10.3390/f14010069
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2527081-3
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  • 10
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    Experimental and Theoretical Explanations for the Initial Difference in the Hydraulic Head in Aquitards
    MDPI AG ; 2022
    In:  Water Vol. 14, No. 19 ( 2022-09-27), p. 3042-
    Details
    In: Water, MDPI AG, Vol. 14, No. 19 ( 2022-09-27), p. 3042-
    Abstract: Accurate estimation of the buoyancy forces exerted on underground structures is a problem in geotechnical engineering that directly impacts the construction safety and cost of these structures. Therefore, studying the buoyancy resistance of underground structures has great scientific and practical value. In this study, an initial difference in the hydraulic head, Δh0, was discovered to be present in aquitards through analysis of water-level data collected from the observation of real-world structures and in laboratory control tests. That is, seepage occurs beyond a threshold Δh0. Analysis of test data reveals that a deviation from Darcy’s law is the theoretical basis for Δh0 and that Δh0 equals the initial hydraulic gradient multiplied by the length of the seepage path. The general consistency between the experimentally measured and theoretically calculated values of Δh0 validates the theoretical explanation for Δh0. The results of this study provide a basis for scientifically calculating the buoyancy resistance required for the construction of underground structures.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    URL: Article
    DOI: 10.3390/w14193042
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2521238-2
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