We present a new crustal thickness map of the Chinese mainland and adjacent areas based on a compilation of previously published data. More than 1900 estimates of crustal thickness from receiver ...function studies were collected and the weighted averages were used to develop a contour map of crustal thickness beneath the Chinese mainland. The combined dataset provided good coverage, especially over eastern and Central China, and our analysis revealed crustal thickness variations of the Chinese mainland with considerably more detail than in previous models. Our crustal thickness map shows a large variation, from a thickness of less than 30km in the Mesozoic basin of eastern China to over 80km in the Tibetan plateau. The thickest crust was found in central Tibet, while the thinnest continental crust was observed beneath eastern China. Normal to slightly thick crust (38–51km) was found for the stable Precambrian basins and orogenic belts. Comparison between our model and other models reveals that the models share similar large-scale and smaller-scale features over large portions of eastern China where the data coverage is good; however, large differences (up to ±25km) in crustal thickness occur in areas with complex crustal structure or poor data coverage. We also evaluated the quality of previous models by comparing them with our newly compiled point observations of crustal thickness.
•Compilation of over 1900 point estimates of crustal thickness from RF analysis.•A new model of crustal thicknesses for the Chinese mainland is constructed.•Lateral variations of Crustal thickness beneath the Chinese mainland are revealed.•The reliability of previous crustal thickness models is evaluated.
Microalgae are emerging platforms for production of a suite of compounds targeting several markets, including food, nutraceuticals, green chemicals, and biofuels. Many of these products, such as ...biodiesel or polyunsaturated fatty acids (PUFAs), derive from lipid metabolism. A general picture of lipid metabolism in microalgae has been deduced from well characterized pathways of fungi and land plants, but recent advances in molecular and genetic analyses of microalgae have uncovered unique features, pointing out the necessity to study lipid metabolism in microalgae themselves. In the past 10 years, in addition to its traditional role as a model for photosynthetic and flagellar motility processes, Chlamydomonas reinhardtii has emerged as a model organism to study lipid metabolism in green microalgae. Here, after summarizing data on total fatty acid composition, distribution of acyl‐lipid classes, and major acyl‐lipid molecular species found in C. reinhardtii, we review the current knowledge on the known or putative steps for fatty acid synthesis, glycerolipid desaturation and assembly, membrane lipid turnover, and oil remobilization. A list of characterized or putative enzymes for the major steps of acyl‐lipid metabolism in C. reinhardtii is included, and subcellular localizations and phenotypes of associated mutants are discussed. Biogenesis and composition of Chlamydomonas lipid droplets and the potential importance of lipolytic processes in increasing cellular oil content are also highlighted.
Cutin and suberin are the polymer matrices for lipophilic cell wall barriers. These barriers control the fluxes of gases, water and solutes, and also play roles in protecting plants from biotic and ...abiotic stresses and in controlling plant morphology. Although they are ubiquitous, cutin and suberin are the least understood of the major plant extracellular polymers. The use of forward and reverse genetic approaches in
Arabidopsis has led to the identification of oxidoreductase and acyltransferase genes involved in the biosynthesis of these polymers. However, major questions about the underlying polymer structure, biochemistry, and intracellular versus extracellular assembly remain to be resolved. The analysis of plant lines with modified cutins and suberins has begun to reveal the inter-relationships between the composition and function of these polymers.
Lipid catabolism in microalgae Kong, Fantao; Romero, Ismael Torres; Warakanont, Jaruswan ...
The New phytologist,
June 2018, Letnik:
218, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Lipid degradation processes are important in microalgae because survival and growth of microalgal cells under fluctuating environmental conditions require permanent remodeling or turnover of membrane ...lipids as well as rapid mobilization of storage lipids. Lipid catabolism comprises two major spatially and temporarily separated steps, namely lipolysis, which releases fatty acids and head groups and is catalyzed by lipases at membranes or lipid droplets, and degradation of fatty acids to acetyl-CoA, which occurs in peroxisomes through the β-oxidation pathway in green microalgae, and can sometimes occur in mitochondria in some other algal species. Herewereview the current knowledge on the enzymes and regulatory proteins involved in lipolysis and peroxisomal β-oxidation and highlight gaps in our understanding of lipid degradation pathways in microalgae. Metabolic use of acetyl-CoA products via glyoxylate cycle and gluconeogenesis is also reviewed. We then present the implication of various cellular processes such as vesicle trafficking, cell cycle and autophagy on lipid turnover. Finally, physiological roles and the manipulation of lipid catabolism for biotechnological applications in microalgae are discussed.
Summary
Long‐chain acyl‐CoA synthetases (LACSs) play many roles in mammals, yeasts and plants, but knowledge on their functions in microalgae remains fragmented. Here via genetic, biochemical and ...physiological analyses, we unraveled the function and roles of LACSs in the model microalga Chlamydomonas reinhardtii.
In vitro assays on purified recombinant proteins revealed that CrLACS1, CrLACS2 and CrLACS3 all exhibited bona fide LACS activities toward a broad range of free fatty acids.
The Chlamydomonas mutants compromised in CrLACS1, CrLACS2 or CrLACS3 did not show any obvious phenotypes in lipid content or growth under nitrogen (N)‐replete condition. But under N‐deprivation, CrLACS1 or CrLACS2 suppression resulted in c. 50% less oil, yet with a higher amount of chloroplast lipids. By contrast, CrLACS3 suppression impaired oil remobilization and cell growth severely during N‐recovery, supporting its role in fatty acid β‐oxidation to provide energy and carbon sources for regrowth. Transcriptomics analysis suggested that the observed lipid phenotypes are likely not due to transcriptional reprogramming but rather a shift in metabolic adjustment.
Taken together, this study provided solid experimental evidence for essential roles of the three Chlamydomonas LACS enzymes in lipid synthesis, remodeling and catabolism, and highlighted the importance of lipid homeostasis in cell growth under nutrient fluctuations.
SUMMARY The Northeastern Tibetan Plateau has thickened crust and is still undergoing strong active crustal shortening and deformation. Crustal anisotropy can provide clues to how the crust is ...currently deforming and evolving. We use an automatic method to analyse the upper-crustal anisotropy of the NE Tibetan Plateau and the adjacent region using local earthquakes recorded at 39 permanent seismic stations during the period 2009–2018. The majority of the dominant fast directions are consistent with the maximum horizontal stress orientation, suggesting that the upper-crustal anisotropy is mainly controlled by the regional or local stress field. Several fault-parallel measurements are observed for stations on or near to the main faults. These fault-parallel fast directions indicate that the main mechanism of upper-crustal anisotropy is associated with shear fabric caused by deformation. Fast directions neither fault-parallel nor stress-parallel are observed at stations lying several kilometres away from fault zones, likely reflecting the combined influence of stress-aligned microcracks and active faults. A comparison between our upper-crustal anisotropy parameters and those inferred from previous anisotropy studies that used receiver function and teleseismic shear wave splitting measurements suggests that the crust has the same deformation mechanisms as mantle anisotropy in the southern part of the Western Qinling Fault, whereas the upper-crustal anisotropic mechanism is different from those of lower crust and mantle anisotropy in the northern part of the Western Qinling Fault. These observations imply that the Western Qinling Fault may be an important boundary fault.
Salinization is a major soil degradation process threatening ecosystems and posing a great challenge to sustainable agriculture and food security worldwide. This study aimed to evaluate the potential ...of state-of-the-art machine learning algorithms in soil salinity (EC1:5) mapping. Further, we predicted the distribution patterns of soil salinity under different future scenarios in the Yellow River Delta. A geodatabase comprising 201 soil samples and 19 conditioning factors (containing data based on remote sensing images such as Landsat, SPOT/VEGETATION PROBA-V, SRTMDEMUTM, Sentinel-1, and Sentinel-2) was used to compare the predictive performance of empirical bayesian kriging regression, random forest, and CatBoost models. The CatBoost model exhibited the highest performance with both training and testing datasets, with an average MAE of 1.86, an average RMSE of 3.11, and an average R2 of 0.59 in the testing datasets. Among explanatory factors, soil Na was the most important for predicting EC1:5, followed by the normalized difference vegetation index and soil organic carbon. Soil EC1:5 predictions suggested that the Yellow River Delta region faces severe salinization, particularly in coastal zones. Among three scenarios with increases in soil organic carbon content (1, 2, and 3 g/kg), the 2 g/kg scenario resulted in the best improvement effect on saline–alkali soils with EC1:5 > 2 ds/m. Our results provide valuable insights for policymakers to improve saline–alkali land quality and plan regional agricultural development.
Summary
Chlorella vulgaris is a fast‐growing fresh‐water microalga cultivated on the industrial scale for applications ranging from food to biofuel production. To advance our understanding of its ...biology and to establish genetics tools for biotechnological manipulation, we sequenced the nuclear and organelle genomes of Chlorella vulgaris 211/11P by combining next generation sequencing and optical mapping of isolated DNA molecules. This hybrid approach allowed us to assemble the nuclear genome in 14 pseudo‐molecules with an N50 of 2.8 Mb and 98.9% of scaffolded genome. The integration of RNA‐seq data obtained at two different irradiances of growth (high light, HL versus low light, LL) enabled us to identify 10 724 nuclear genes, coding for 11 082 transcripts. Moreover, 121 and 48 genes, respectively, were found in the chloroplast and mitochondrial genome. Functional annotation and expression analysis of nuclear, chloroplast and mitochondrial genome sequences revealed particular features of Chlorella vulgaris. Evidence of horizontal gene transfers from chloroplast to mitochondrial genome was observed. Furthermore, comparative transcriptomic analyses of LL versus HL provided insights into the molecular basis for metabolic rearrangement under HL versus LL conditions leading to enhanced de novo fatty acid biosynthesis and triacylglycerol accumulation. The occurrence of a cytosolic fatty acid biosynthetic pathway could be predicted and its upregulation upon HL exposure was observed, consistent with the increased lipid amount under HL conditions. These data provide a rich genetic resource for future genome editing studies, and potential targets for biotechnological manipulation of Chlorella vulgaris or other microalgae species to improve biomass and lipid productivity.
Significance Statement
Microalgae cultivation is one of the most promising strategies for novel food or biofuel production. High‐quality genome information is required for understanding algae biology, for their biotechnological optimization and for genome editing applications. Here, the genome of Chlorella vulgaris, one of the green algae species with the highest productivity potential, is presented and functionally annotated, revealing notable features among Chlorophyta.
The disassembly of lipid droplets in Chlamydomonas Li‐Beisson, Yonghua; Kong, Fantao; Wang, Pengfei ...
The New phytologist,
August 2021, 2021-08-00, 20210801, 2021-08, Letnik:
231, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Summary
Lipid droplets (LDs) are ubiquitous and specialized organelles in eukaryotic cells. Consisting of a triacylglycerol core surrounded by a monolayer of membrane lipids, LDs are decorated with ...proteins and have myriad functions, from carbon/energy storage to membrane lipid remodeling and signal transduction. The biogenesis and turnover of LDs are therefore tightly coordinated with cellular metabolic needs in a fluctuating environment. Lipid droplet turnover requires remodeling of the protein coat, lipolysis, autophagy and fatty acid β‐oxidation. Several key components of these processes have been identified in Chlamydomonas (Chlamydomonas reinhardtii), including the major lipid droplet protein, a CXC‐domain containing regulatory protein, the phosphatidylethanolamine‐binding DTH1 (DELAYED IN TAG HYDROLYSIS1), two lipases and two enzymes involved in fatty acid β‐oxidation. Here, we review LD turnover and discuss its physiological significance in Chlamydomonas, a major model green microalga in research on algal oil.
The concentrations of trace elements in agricultural soils directly affect the ecological security and quality of agricultural products. A comprehensive study aimed at quantitatively analyze the ...effects of anthropogenic and natural environmental factors on the spatial distribution of heavy metals (HMs) and selenium (Se) in agricultural soils in a typical grain producing area of China. Factors considered in this study were parent rock, soil physicochemical properties, topography, precipitation, mine activity, and vegetation. Results showed that the median values of Zn, Cd, Cr, and Cu of 111 topsoil samples exceeded the background values of Guangxi province but were lower than the relevant national soil quality standards, and 85% of soil samples were classified as having rich Se levels (0.40 −3.0 mg kg−1). The potential ecological risk index of soil heavy metals as a whole was low, with Cd in 9% of the samples posing moderate ecological risk. The concentrations of heavy metals and Se were relatively high in soils from shale rock. Soil properties, mainly Fe2O3 and Mn played a dominant role on soil HMs and Se concentrations. Based on GeoDetector, we found that the interaction effects of two factors on the spatial differentiation of soil HMs and Se were greater than their sum effect. Among the factors, Mn enhanced the explanatory power of the model the most when interacting with other factors for soil Zn; the greatest interactive effect was between distance from mining area and Mn for Cd (q = 0.70); Fe2O3 significantly promoted the spatial differentiation of soil Cr, Cu and Se when interacting with other factors (q > 0.50). These findings contribute to a better understanding of the factors that drive the distribution of HMs and Se in agricultural soils.
•Potential ecological risk index of soil heavy metals was low level and Se was rich.•The contents of heavy metals and Se were relatively high in soils from shale rock.•Correlation, PCA, and GeoDetector models were useful for studying driving factors.•Soil Mn∩Mining exhibited the strongest impact on distributions of soil Zn and Cd.•Fe2O3 were primary factors influencing the concentrations of soil Cr, Cu and Se.
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