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1.
Nature ; 619(7971): 761-767, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37495878

RESUMO

China's goal to achieve carbon (C) neutrality by 2060 requires scaling up photovoltaic (PV) and wind power from 1 to 10-15 PWh year-1 (refs. 1-5). Following the historical rates of renewable installation1, a recent high-resolution energy-system model6 and forecasts based on China's 14th Five-year Energy Development (CFED)7, however, only indicate that the capacity will reach 5-9.5 PWh year-1 by 2060. Here we show that, by individually optimizing the deployment of 3,844 new utility-scale PV and wind power plants coordinated with ultra-high-voltage (UHV) transmission and energy storage and accounting for power-load flexibility and learning dynamics, the capacity of PV and wind power can be increased from 9 PWh year-1 (corresponding to the CFED path) to 15 PWh year-1, accompanied by a reduction in the average abatement cost from US$97 to US$6 per tonne of carbon dioxide (tCO2). To achieve this, annualized investment in PV and wind power should ramp up from US$77 billion in 2020 (current level) to US$127 billion in the 2020s and further to US$426 billion year-1 in the 2050s. The large-scale deployment of PV and wind power increases income for residents in the poorest regions as co-benefits. Our results highlight the importance of upgrading power systems by building energy storage, expanding transmission capacity and adjusting power load at the demand side to reduce the economic cost of deploying PV and wind power to achieve carbon neutrality in China.

2.
Nature ; 609(7926): 299-306, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36071193

RESUMO

The potential of mitigation actions to limit global warming within 2 °C (ref. 1) might rely on the abundant supply of biomass for large-scale bioenergy with carbon capture and storage (BECCS) that is assumed to scale up markedly in the future2-5. However, the detrimental effects of climate change on crop yields may reduce the capacity of BECCS and threaten food security6-8, thus creating an unrecognized positive feedback loop on global warming. We quantified the strength of this feedback by implementing the responses of crop yields to increases in growing-season temperature, atmospheric CO2 concentration and intensity of nitrogen (N) fertilization in a compact Earth system model9. Exceeding a threshold of climate change would cause transformative changes in social-ecological systems by jeopardizing climate stability and threatening food security. If global mitigation alongside large-scale BECCS is delayed to 2060 when global warming exceeds about 2.5 °C, then the yields of agricultural residues for BECCS would be too low to meet the Paris goal of 2 °C by 2200. This risk of failure is amplified by the sustained demand for food, leading to an expansion of cropland or intensification of N fertilization to compensate for climate-induced yield losses. Our findings thereby reinforce the urgency of early mitigation, preferably by 2040, to avoid irreversible climate change and serious food crises unless other negative-emission technologies become available in the near future to compensate for the reduced capacity of BECCS.


Assuntos
Agricultura , Produtos Agrícolas , Segurança Alimentar , Aquecimento Global , Agricultura/métodos , Agricultura/tendências , Atmosfera/química , Dióxido de Carbono/análise , Sequestro de Carbono , Produtos Agrícolas/crescimento & desenvolvimento , Ecossistema , Retroalimentação , Segurança Alimentar/métodos , Aquecimento Global/prevenção & controle , Aquecimento Global/estatística & dados numéricos , Objetivos , Humanos , Nitrogênio/análise , Estações do Ano , Temperatura , Fatores de Tempo
3.
Environ Sci Technol ; 58(16): 7099-7112, 2024 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-38536960

RESUMO

Reduced nitrogen-containing organic compounds (NOCs) in aerosols play a crucial role in altering their light-absorption properties, thereby impacting regional haze and climate. Due to the low concentration levels of individual NOCs in the air, the utilization of accurate detection and quantification technologies becomes essential. For the first time, this study investigated the diurnal variation, chemical characteristics, and potential formation pathways of NOCs in urban ambient aerosols in Shanghai using a versatile aerosol concentration enrichment system (VACES) coupled with HPLC-Q-TOF-MS. The results showed that NOCs accounted over 60% of identified components of urban organic aerosols, with O/N < 3 compounds being the major contributors (>70%). The predominance of the positive ionization mode suggested the prevalence of reduced NOCs. Higher relative intensities and number fractions of NOCs were observed during nighttime, while CHO compounds showed an opposite trend. Notably, a positive correlation between the intensity of NOCs and ammonium during the nighttime was observed, suggesting that the reaction of ammonium to form imines may be a potential pathway for the formation of reduced NOCs during the nighttime. Seven prevalent types of reduced NOCs in autumn and winter were identified and characterized by an enrichment of CH2 long-chain homologues. These NOCs included alkyl, cyclic, and aromatic amides in CHON compounds, as well as heterocyclic or cyclic amines and aniline homologue series in CHN compounds, which were associated with anthropogenic activities and may be capable of forming light-absorbing chromophores or posing harm to human health. The findings highlight the significant contributions of both primary emissions and ammonium chemistry, particularly amination processes, to the pollution of reduced NOCs in Shanghai's atmosphere.


Assuntos
Aerossóis , Poluentes Atmosféricos , Atmosfera , China , Atmosfera/química , Poluentes Atmosféricos/análise , Compostos Orgânicos/análise , Monitoramento Ambiental , Nitrogênio/análise
4.
Environ Sci Technol ; 58(10): 4691-4703, 2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38323401

RESUMO

The negative effects of air pollution, especially fine particulate matter (PM2.5, particles with an aerodynamic diameter of ≤2.5 µm), on human health, climate, and ecosystems are causing significant concern. Nevertheless, little is known about the contributions of emerging pollutants such as plastic particles to PM2.5 due to the lack of continuous measurements and characterization methods for atmospheric plastic particles. Here, we investigated the levels of fine plastic particles (FPPs) in PM2.5 collected in urban Shanghai at a 2 h resolution by using a novel versatile aerosol concentration enrichment system that concentrates ambient aerosols up to 10-fold. The FPPs were analyzed offline using the combination of spectroscopic and microscopic techniques that distinguished FPPs from other carbon-containing particles. The average FPP concentrations of 5.6 µg/m3 were observed, and the ratio of FPPs to PM2.5 was 13.2% in this study. The FPP sources were closely related to anthropogenic activities, which pose a potential threat to ecosystems and human health. Given the dramatic increase in plastic production over the past 70 years, this study calls for better quantification and control of FPP pollution in the atmosphere.


Assuntos
Poluentes Atmosféricos , Humanos , Poluentes Atmosféricos/análise , Ecossistema , Monitoramento Ambiental/métodos , China , Material Particulado/análise , Estações do Ano , Aerossóis/análise
5.
Proc Natl Acad Sci U S A ; 118(12)2021 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-33798097

RESUMO

Heavy monsoon rainfall ravaged a large swath of East Asia in summer 2020. Severe flooding of the Yangtze River displaced millions of residents in the midst of a historic public health crisis. This extreme rainy season was not anticipated from El Niño conditions. Using observations and model experiments, we show that the record strong Indian Ocean Dipole event in 2019 is an important contributor to the extreme Yangtze flooding of 2020. This Indian Ocean mode and a weak El Niño in the Pacific excite downwelling oceanic Rossby waves that propagate slowly westward south of the equator. At a mooring in the Southwest Indian Ocean, the thermocline deepens by a record 70 m in late 2019. The deepened thermocline helps sustain the Indian Ocean warming through the 2020 summer. The Indian Ocean warming forces an anomalous anticyclone in the lower troposphere over the Indo-Northwest Pacific region and intensifies the upper-level westerly jet over East Asia, leading to heavy summer rainfall in the Yangtze Basin. These coupled ocean-atmosphere processes beyond the equatorial Pacific provide predictability. Indeed, dynamic models initialized with observed ocean state predicted the heavy summer rainfall in the Yangtze Basin as early as April 2020.


Assuntos
Inundações , Rios , Meio Ambiente , Inundações/história , História do Século XXI , Humanos , Oceano Índico , Modelos Teóricos
6.
Proc Natl Acad Sci U S A ; 118(33)2021 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-34380740

RESUMO

The real-time monitoring of reductions of economic activity by containment measures and its effect on the transmission of the coronavirus (COVID-19) is a critical unanswered question. We inferred 5,642 weekly activity anomalies from the meteorology-adjusted differences in spaceborne tropospheric NO2 column concentrations after the 2020 COVID-19 outbreak relative to the baseline from 2016 to 2019. Two satellite observations reveal reincreasing economic activity associated with lifting control measures that comes together with accelerating COVID-19 cases before the winter of 2020/2021. Application of the near-real-time satellite NO2 observations produces a much better prediction of the deceleration of COVID-19 cases than applying the Oxford Government Response Tracker, the Public Health and Social Measures, or human mobility data as alternative predictors. A convergent cross-mapping suggests that economic activity reduction inferred from NO2 is a driver of case deceleration in most of the territories. This effect, however, is not linear, while further activity reductions were associated with weaker deceleration. Over the winter of 2020/2021, nearly 1 million daily COVID-19 cases could have been avoided by optimizing the timing and strength of activity reduction relative to a scenario based on the real distribution. Our study shows how satellite observations can provide surrogate data for activity reduction during the COVID-19 pandemic and monitor the effectiveness of containment to the pandemic before vaccines become widely available.


Assuntos
Poluição do Ar/efeitos adversos , COVID-19/epidemiologia , Aprendizado de Máquina , COVID-19/etiologia , China/epidemiologia , Humanos , Fatores Socioeconômicos
7.
Adv Atmos Sci ; : 1-28, 2023 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-37359908

RESUMO

Studies of the multi-scale climate variability of the Asian monsoon are essential to an advanced understanding of the physical processes of the global climate system. In this paper, the progress achieved in this field is systematically reviewed, with a focus on the past several years. The achievements are summarized into the following topics: (1) the onset of the South China Sea summer monsoon; (2) the East Asian summer monsoon; (3) the East Asian winter monsoon; and (4) the Indian summer monsoon. Specifically, new results are highlighted, including the advanced or delayed local monsoon onset tending to be synchronized over the Arabian Sea, Bay of Bengal, Indochina Peninsula, and South China Sea; the basic features of the record-breaking mei-yu in 2020, which have been extensively investigated with an emphasis on the role of multi-scale processes; the recovery of the East Asian winter monsoon intensity after the early 2000s in the presence of continuing greenhouse gas emissions, which is believed to have been dominated by internal climate variability (mostly the Arctic Oscillation); and the accelerated warming over South Asia, which exceeded the tropical Indian Ocean warming, is considered to be the main driver of the Indian summer monsoon rainfall recovery since 1999. A brief summary is provided in the final section along with some further discussion on future research directions regarding our understanding of the Asian monsoon variability.

8.
BMC Plant Biol ; 21(1): 513, 2021 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-34736392

RESUMO

BACKGROUND: Drought stress severely limits maize seedling growth and crop yield. Previous studies have elucidated the mechanisms by which maize acquires drought resistance and contends with water deficiency. However, the link between the physiological and molecular variations among maize cultivars are unknown. Here, physiological and proteomic analyses were conducted to compare the stress responses of two maize cultivars with contrasting drought stress tolerance. RESULTS: The physiological analysis showed that the drought-tolerant SD609 maize variety maintains relatively high photochemical efficiency by enhancing its protective cyclic electron flow (CEF) mechanism and antioxidative enzymes activities. Proteomics analysis revealed that 198 and 102 proteins were differentially expressed in SD609 and the drought-sensitive SD902 cultivar, respectively. GO and KEGG enrichments indicated that SD609 upregulated proteins associated with photosynthesis, antioxidants/detoxifying enzymes, molecular chaperones and metabolic enzymes. Upregulation of the proteins related to PSII repair and photoprotection improved photochemical capacity in SD609 subjected to moderate drought stress. In SD902, however, only the molecular chaperones and sucrose synthesis pathways were induced and they failed to protect the impaired photosystem. Further analysis demonstrated that proteins related to the electron transport chain (ETC) and redox homeostasis as well as heat shock proteins (HSPs) may be important in protecting plants from drought stress. CONCLUSIONS: Our experiments explored the mechanism of drought tolerance and clarified the interconnections between the physiological and proteomic factors contributing to it. In summary, our findings aid in further understanding of the drought tolerance mechanisms in maize.


Assuntos
Proteínas de Plantas/metabolismo , Proteômica/métodos , Zea mays/metabolismo , Secas , Regulação da Expressão Gênica de Plantas , Fotossíntese/genética , Fotossíntese/fisiologia , Proteínas de Plantas/genética , Plântula/genética , Plântula/metabolismo , Zea mays/genética
9.
J Acoust Soc Am ; 149(6): 4366, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34241465

RESUMO

An approach of broadband mode separation in shallow water is proposed using phase speed extracted from one hydrophone and solved with sparse Bayesian learning (SBL). The approximate modal dispersion relation, connecting the horizontal wavenumbers (phase velocities) for multiple frequencies, is used to build the dictionary matrix for SBL. Given a multi-frequency pressure vector on one hydrophone, SBL estimates a set of sparse coefficients for a large number of atoms in the dictionary. With the estimated coefficients and corresponding atoms, the separated normal modes are retrieved. The presented method can be used for impulsive or known-form signals in a shallow-water environment while no bottom information is required. The simulation results demonstrate that the proposed approach is adapted to the environment where both the reflected and refracted modes coexist, whereas the performance of the time warping transformation degrades significantly in this scenario.

10.
BMC Evol Biol ; 20(1): 91, 2020 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-32727363

RESUMO

BACKGROUND: The SIAMESE (SIM) locus is a cell-cycle kinase inhibitor (CKI) gene that has to date been identified only in plants; it encodes a protein that promotes transformation from mitosis to endoreplication. Members of the SIAMESE-RELATED (SMR) family have similar functions, and some are related to cell-cycle responses and abiotic stresses. However, the functions of SMRs are poorly understood in maize (Zea mays L.). RESULTS: In the present study, 12 putative SMRs were identified throughout the entire genome of maize, and these were clustered into six groups together with the SMRs from seven other plant species. Members of the ZmSMR family were divided into four groups according to their protein sequences. Various cis-acting elements in the upstream sequences of ZmSMRs responded to abiotic stresses. Expression analyses revealed that all ZmSMRs were upregulated at 5, 20, 25, and 35 days after pollination. In addition, we found that ZmSMR9/11/12 may have regulated the initiation of endoreplication in endosperm central cells. Additionally, ZmSMR2/10 may have been primarily responsible for the endoreplication regulation of outer endosperm or aleurone cells. The relatively high expression levels of almost all ZmSMRs in the ears and tassels also implied that these genes may function in seed development. The effects of treatments with ABA, heat, cold, salt, and drought on maize seedlings and expression of ZmSMR genes suggested that ZmSMRs were strongly associated with response to abiotic stresses. CONCLUSION: The present study is the first to conduct a genome-wide analysis of members of the ZmSMR family by investigating their locations in chromosomes, identifying regulatory elements in their promoter regions, and examining motifs in their protein sequences. Expression analysis of different endosperm developmental periods, tissues, abiotic stresses, and hormonal treatments suggests that ZmSMR genes may function in endoreplication and regulate the development of reproductive organs. These results may provide valuable information for future studies of the functions of the SMR family in maize.


Assuntos
Evolução Molecular , Regulação da Expressão Gênica de Plantas , Genoma de Planta , Família Multigênica , Zea mays/genética , Sequência de Aminoácidos , Sequência de Bases , Cromossomos de Plantas/genética , Sequência Conservada/genética , Endosperma/genética , Duplicação Gênica , Genes de Plantas , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Regiões Promotoras Genéticas/genética , Análise de Regressão , Especificidade da Espécie , Estresse Fisiológico/efeitos dos fármacos , Sintenia/genética
11.
J Acoust Soc Am ; 147(6): 3729, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32611184

RESUMO

The horizontal wavenumbers and modal depth functions are estimated by block sparse Bayesian learning (BSBL) for broadband signals received by a vertical line array in shallow-water waveguides. The dictionary matrix consists of multi-frequency modal depth functions derived from shooting methods given a large set of hypothetical horizontal wavenumbers. The dispersion relation for multi-frequency horizontal wavenumbers is also taken into account to generate the dictionary. In this dictionary, only a few of the entries are used to describe the pressure field. These entries represent the modal depth functions and associated wavenumbers. With the constraint of block sparsity, the BSBL approach is shown to retrieve the horizontal wavenumbers and corresponding modal depth functions with high precision, while a priori knowledge of sea bottom, moving source, and source locations is not needed. The performance is demonstrated by simulations and experimental data.

12.
J Acoust Soc Am ; 147(1): 285, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32006998

RESUMO

The ray-based blind deconvolution algorithm can provide an estimate of the channel impulse responses (CIRs) between a shipping source of opportunity and the elements of a receiving array by estimating the unknown phase of this random source through wideband beamforming along a well-resolved ray path. However, due to the shallow effective depth (typically <10 m) and low frequency content (typically less than a few kHz) associated with shipping sources, the interfering direct and surface arriving pair and subsequent bottom and surface-bottom arrival pair cannot always be resolved in the CIR arrival-time structure. Nevertheless, this study demonstrates that the bottom reflection loss can be inferred from the ratio of the magnitude spectra of these two arrival pairs if a frequency-dependent correction (which can be purely data based) is applied to correct for the dipole source effect. The feasibility of the proposed approach is demonstrated to invert for the geoacoustic parameters of a soft-layer covering the ocean floor using a nonlinear least-square algorithm.

13.
Cytometry A ; 93(2): 213-221, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28976638

RESUMO

Particle-size distribution, granular structure, and composition significantly affect the physicochemical properties, rheological properties, and nutritional function of starch. Flow cytometry and flow sorting are widely considered convenient and efficient ways of classifying and separating natural biological particles or other substances into subpopulations, respectively, based on the differential response of each component to stimulation by a light beam; the results allow for the correlation analysis of parameters. In this study, different types of starches isolated from waxy maize, sweet maize, high-amylose maize, pop maize, and normal maize were initially classified into various subgroups by flow cytometer and then collected through flow sorting to observe their morphology and particle-size distribution. The results showed that a 0.25% Gelzan solution served as an optimal reagent for keeping individual starch particles homogeneously dispersed in suspension for a relatively long time. The bivariate flow cytometric population distributions indicated that the starches of normal maize, sweet maize, and pop maize were divided into two subgroups, whereas high-amylose maize starch had only one subgroup. Waxy maize starch, conversely, showed three subpopulations. The subgroups sorted by flow cytometer were determined and verified in terms of morphology and granule size by scanning electron microscopy and laser particle distribution analyzer. Results showed that flow cytometry can be regarded as a novel method for classifying and sorting starch granules. © 2017 International Society for Advancement of Cytometry.


Assuntos
Citometria de Fluxo/métodos , Tamanho da Partícula , Amido/análise , Zea mays/química , Zea mays/citologia
14.
BMC Vet Res ; 14(1): 44, 2018 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-29433480

RESUMO

BACKGROUND: The natural incidence of left displacement of abomasum (LDA) in dairy cows was high. The diagnosis of LDA usually relies on characteristic physical exam findings but that transabdominal ultrasound is a useful technique that has been applied to the diagnosis of gastrointestinal diseases of dairy cows in equivocal cases. METHODS: Forty dairy cows with LDA were clinically and ultrasonographically examined to determine the position and the echogenic property of the abomasum. The cows were examined ultrasonographically on the left side, from the 9th intercostal space (ICS) to the 12th ICS as well as the ventral left abdomen before and after reposition surgery. RESULTS: The vital signs were within normal range in most of the cows and the 'pinging' were clearly heard in 37 cows. The abomasal gas cap was visualized from the 9th to 12th ICS in 37 cows and characterized by reverberation artifacts. The abomasal ingesta appeared as homogeneous hypoechoic fluid with scattered hyperechoic foci and were mainly visible in the median region and ventral region of the 9th to 11th ICS in 35 cows. The pyloric canal was detected from the ventral left abdomen wall in 30 cows and appeared as a loop with hypoechogenic wall and echogenic luminal contents in cross section. CONCLUSION: These typical ultrasonograms, including reverberation artifacts, homogenous hypoechoic structures, are important diagnostic feature in ultrasonography of LDA. Furthermore, the circular acoustic image structure of the pyloric canal is an important characteristic of LDA, so it can be used as an important diagnostic basis of LDA.


Assuntos
Abomaso/diagnóstico por imagem , Doenças dos Bovinos/diagnóstico por imagem , Gastropatias/veterinária , Abomaso/cirurgia , Animais , Bovinos/cirurgia , Doenças dos Bovinos/cirurgia , Feminino , Gastropatias/diagnóstico por imagem , Gastropatias/cirurgia , Ultrassonografia/veterinária
15.
J Dairy Res ; 85(2): 157-162, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29785900

RESUMO

Dairy cows with type II ketosis display hepatic fat accumulation and hyperinsulinemia, but the underlying mechanism is not completely clear. This study aimed to clarify the regulation of lipid metabolism by insulin in cow hepatocytes. In vitro, cow hepatocytes were treated with 0, 1, 10, or 100 nm insulin in the presence or absence of AICAR (an AMP-activated protein kinase alpha (AMPKα) activator). The results showed that insulin decreased AMPKα phosphorylation. This inactivation of AMPKα increased the gene and protein expression levels of carbohydrate responsive element-binding protein (ChREBP) and sterol regulatory element-binding protein-1c (SREBP-1c), which downregulated the expression of lipogenic genes, thereby decreasing lipid biosynthesis. Furthermore, AMPKα inactivation decreased the gene and protein expression levels of peroxisome proliferator-activated receptor-α (PPARα), which upregulated the expression of lipid oxidation genes, thereby increasing lipid oxidation. In addition, insulin decreased the very low density lipoprotein (VLDL) assembly. Consequently, triglyceride content was significantly increased in insulin treated hepatocytes. Activation of AMPKα induced by AICAR could reverse the effect of insulin on PPARα, SREBP-1c, and ChREBP, thereby decreasing triglyceride content. These results indicate that insulin inhibits the AMPKα signaling pathway to increase lipid synthesis and decrease lipid oxidation and VLDL assembly in cow hepatocytes, thereby inducing TG accumulation. This mechanism could partly explain the causal relationship between hepatic fat accumulation and hyperinsulinemia in dairy cows with type II ketosis.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Bovinos , Hepatócitos/enzimologia , Insulina/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacologia , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/análise , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Doenças dos Bovinos/metabolismo , Células Cultivadas , Feminino , Expressão Gênica/efeitos dos fármacos , Hepatócitos/metabolismo , Insulina/sangue , Cetose/metabolismo , Cetose/veterinária , Metabolismo dos Lipídeos/genética , Lipoproteínas VLDL/metabolismo , Oxirredução , PPAR alfa/análise , PPAR alfa/genética , Ribonucleotídeos/farmacologia , Proteína de Ligação a Elemento Regulador de Esterol 1/análise , Proteína de Ligação a Elemento Regulador de Esterol 1/genética , Triglicerídeos/metabolismo
16.
J Dairy Res ; 83(1): 51-7, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26869111

RESUMO

Elevated levels of blood interleukin-1ß (IL-1ß), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) increase insulin resistance and result in inflammation. It is not clear whether elevated blood level of acetoacetate (ACAC) and decreased blood level of glucose, which are the predominant characteristics of clinical biochemistry in ketotic dairy cows, increase proinflammatory cytokines and subsequent inflammation. The objective of this study was to test the hypothesis that ACAC and glucose activate the NF-κB signalling pathway to regulate cytokines expression in bovine hepatocytes. Bovine hepatocytes were cultured with ACAC (0-4.8 mm) and glucose (0-5.55 mm) with or without NF-κB inhibitor PDTC for 24 h. The secretion and mRNA levels of cytokines were determined by enzyme-linked immunosorbent assay (ELISA) and real-time fluorescence quantitative polymerase chain reaction (qRT-PCR). The NF-κB signalling pathway activation was evaluated by western blotting. Results showed that the secretion and expression of IL-1ß, IL-6 and TNF-α increased in an ACAC dose-dependent manner. Additionally, there was an increase in the secretion and mRNA expression of these three cytokines in glucose treatment group, which increased significantly when the glucose concentrations exceed 3.33 mm. Furthermore, both ACAC and glucose upregulated NF-κB p65 protein expression and IκBα phosphorylation levels. However, these effects were reduced by PDTC. These results demonstrate that elevated levels of ACAC and glucose increase the synthesis and expression of proinflammatory factors by activating NF-κB signalling pathway in hepatocytes, which may contribute to inflammation injury in ketotic dairy cows.


Assuntos
Acetoacetatos/farmacologia , Citocinas/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Glucose/farmacologia , Hepatócitos/efeitos dos fármacos , NF-kappa B/metabolismo , Animais , Bovinos , Células Cultivadas , Citocinas/genética , Hepatócitos/metabolismo , NF-kappa B/genética , Prolina/análogos & derivados , Prolina/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transdução de Sinais/efeitos dos fármacos , Tiocarbamatos/farmacologia
17.
J Cell Biochem ; 116(6): 1070-9, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25558823

RESUMO

ß-hydroxybutyric acid (BHBA), an important metabolite in ß-oxidation, is involved in the development of ketosis in dairy cows. It is known that AMP-activated protein kinase (AMPK) signaling pathway plays an important role in the regulation of lipid metabolism in hepatocytes. In the present study, bovine hepatocytes were treated with BHBA at variable concontrations and Compound C (Cpd C, an AMPK inhibitor) to investigate the effects of BHBA on the AMPK signaling pathway. The results showed that when the concentration of BHBA reached 1.2 mM, the AMPK signaling pathway was activated and the expression of sterol regulatory element binding protein-1c (SREBP-1c) as well as its target genes were significantly decreased. And these decreases were blocked by Cpd C. The binding activity and nucleus translocation of SREBP-1c showed a similar trend. The expression of peroxisome proliferator activated receptor-α (PPARα), carbohydrates response element binding protein (ChREBP) and their target genes were significantly increased while they were negatively suppressed by the Cpd C. The content of triglyceride (TG) had no obviously change in the BHBA and Cpd C-treated groups. These results indicate that BHBA can activate AMPK signaling pathway and regulate lipid synthesis and lipid oxidation genes of AMPK but showed no effect on TG in bovine hepatocytes.


Assuntos
Ácido 3-Hidroxibutírico/farmacologia , Proteínas Quinases Ativadas por AMP/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Proteínas Quinases Ativadas por AMP/genética , Animais , Bovinos , Células Cultivadas , Hepatócitos/citologia , Transdução de Sinais/efeitos dos fármacos , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo
18.
Cell Physiol Biochem ; 37(6): 2115-24, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26599760

RESUMO

BACKGROUND/AIMS: In dairy cows, ß-hydroxybutyrate (BHBA) is utilized as precursors of de novo synthesized fatty acids in mammary gland. Ketotic cows are characterized by excessive negative energy balance (NEB), which can further increase the blood BHBA concentration. Sterol regulatory element-binding protein1 (SREBP1) and cell death-inducing DNA fragmentation factor-alpha-like effector α (Cidea) play crucial roles in lipid synthesis. Therefore, we hypothesized that BHBA could stimulate SREBP1/Cidea pathway to increase milk fat synthesis in bovine mammary epithelial cells. METHODS: Bovine mammary epithelial cells were treated with different concentrations of BHBA and transfected with adenovirus to silence SREBP1 expression. The effects of BHBA on the lipid synthesis in bovine mammary epithelial cells were investigated. RESULTS: The results showed that BHBA could significantly increase the expression of SREBP1, fatty acid synthase (FAS), acetyl-CoA carboxylase α (ACC-α), Cidea and diacylglycerol transferase-1 (DGAT-1), as well as the triglycerides (TG) content in bovine mammary epithelial cells. BHBA treatment also increased the transfer of mature SREBP1 to nucleus compared with control group. However, SREBP1 silencing could significantly down-regulate the overexpression of FAS, ACC-α, Cidea and DGAT-1, as well as TG content induced by BHBA. CONCLUSION: The present data indicate that BHBA can significantly increase TG secretion mediated by SREBP1 in bovine mammary epithelial cells.


Assuntos
Ácido 3-Hidroxibutírico/farmacologia , Ácidos Graxos/biossíntese , Glândulas Mamárias Humanas/efeitos dos fármacos , Proteína de Ligação a Elemento Regulador de Esterol 1/fisiologia , Animais , Bovinos , Células Cultivadas , Ensaio de Imunoadsorção Enzimática , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Humanos , Glândulas Mamárias Humanas/citologia , Glândulas Mamárias Humanas/metabolismo
19.
J Acoust Soc Am ; 136(1): 53-65, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24993195

RESUMO

Signals propagating in waveguides can be decomposed into normal modes that exhibit dispersive characteristics. Based on the dispersion analysis, the warping transformation can be used to improve the modal separability. Different from the warping transformation defined using an ideal waveguide model, an improved warping operator is presented in this paper based on the beam-displacement ray-mode (BDRM) theory, which can be adapted to low-frequency signals in a general shallow water waveguide. For the sake of obtaining the warping operators for the general waveguides, the dispersion formula is first derived. The approximate dispersion relation can be achieved with adequate degree of accuracy for the waveguides with depth-dependent sound speed profiles (SSPs) and acoustic bottoms. Performance and accuracy of the derived formulas for the dispersion curves are evaluated by comparing with the numerical results. The derived warping operators are applied to simulations, which show that the non-linear dispersion structures can be well compensated by the proposed warping operators.

20.
Sci Bull (Beijing) ; 69(9): 1332-1341, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38485623

RESUMO

A troubling feedback loop, where drier soil contributes to hotter climates, has been widely recognized. This study, drawing on climate model simulations, reveals that maintaining current global soil moisture levels could significantly alleviate 32.9% of land warming under low-emission scenarios. This action could also postpone reaching critical warming thresholds of 1.5 °C and 2.0 °C by at least a decade. Crucially, preserving soil moisture at current levels could prevent noticeable climate change impacts across 42% of the Earth's land, a stark deviation from projections suggesting widespread impacts before the 2060s. To combat soil drying, afforestation in mid-to-low latitude regions within the next three decades is proposed as an effective strategy to increase surface water availability. This underscores the substantial potential of nature-based solutions for managing soil moisture, benefiting both climate change mitigation and ecological enhancement.

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