Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.919
Filtrar
1.
Microb Cell Fact ; 22(1): 5, 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36609255

RESUMO

BACKGROUND: New antibiotics are urgently needed in clinical treatment of superdrug-resistant bacteria. Nonribosomal peptides (NRPs) are a major source of antibiotics because they exhibit structural diversity, and unique antibacterial mechanisms and resistance. Analysis of gene clusters of S. agglomeratus 5-1-3 showed that Clusters 3, 6, 12, 21, and 28 were used to synthesize NRPs. Here, we examined secondary metabolites of S. agglomeratus 5-1-3 isolated from soils in the Qinghai-Tibet Plateau, China, for NRPs with antibacterial activity. RESULTS: We isolated a total of 36 Streptomyces strains with distinct colony morphological characteristics from 7 soil samples. We screened 8 Streptomyces strains resistant to methicillin-resistant Staphylococcus aureus (MRSA). We then selected S. agglomeratus 5-1-3 for further study based on results of an antibacterial activity test. Here, we isolated three compounds from S. agglomeratus 5-1-3 and characterized their properties. The crude extract was extracted with ethyl acetate and purified with column chromatography and semipreparative high-performance liquid chromatography (HPLC). We characterized the three compounds using NMR analyses as echinomycin (1), 5,7,4'-trihydroxy-3.3',5'-trimethoxy flavone (2), and 2,6,2', 6'-tetramethoxy-4,4-bis(2,3-epoxy-1-hydroxypropyl)-biphenyl (3). We tested the antibacterial activity of pure compounds from strain 5-1-3 with the Oxford cup method. NRP echinomycin (1) showed excellent anti-MRSA activity with a minimum inhibitory concentration (MIC) of 2.0 µg/mL. Meanwhile, MIC of compound 2 and 3 was 128.0 µg/mL for both. In addition, 203 mg of echinomycin was isolated from 10 L of the crude extract broth of strain 5-1-3. CONCLUSION: In this study, S. agglomeratus 5-1-3 with strong resistance to MRSA was isolated from the soils in the Qinghai-Tibet Plateau. Strain 5-1-3 had a high yield of echinomycin (1) an NRP with a MIC of 2 µg/mL against MRSA. We propose that echinomycin derived from S. agglomeratus 5-1-3 may be a potent antibacterial agent for pharmaceutical use.


Assuntos
Equinomicina , Staphylococcus aureus Resistente à Meticilina , Streptomyces , Tibet , Antibacterianos/química , Streptomyces/química , Testes de Sensibilidade Microbiana , Misturas Complexas , Solo
2.
Sci Rep ; 13(1): 314, 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36609398

RESUMO

Interword spaces exist in the texts of many languages that use alphabetic writing systems. In most cases, interword spaces, as a kind of word boundary information, play an important role in the reading process of readers. Tibetan also uses alphabetic writing, its text has no spaces between words as word boundary markers. Instead, there are intersyllable tshegs (" "), which are superscript dots. Interword spaces play an important role in reading as word boundary information. Therefore, it is interesting to investigate the role of tshegs and what effect replacing tshegs with spaces will have on Tibetan reading. To answer these questions, Experiment 1 was conducted in which 72 Tibetan undergraduates read three-syllable-boundary conditions (normal, spaced, and untsheged). However, in Experiment 1, because we performed the experimental operations of deleting tshegs and replacing tshegs, the spatial information distribution of Tibetan sentences under different operating conditions was different, which may have a certain potential impact on the experimental results. To rule out the underlying confounding factor, in Experiment 2, 58 undergraduates read sentences for both untsheged and alternating-color conditions. Overall, the global and local analyses revealed that tshegs, spaces, and alternating-color markers as syllable boundaries can help readers segment syllables in Tibetan reading. In Tibetan reading, both spaces and tshegs are effective visual syllable segmentation cues, and spaces are more effective visual syllable segmentation cues than tshegs.


Assuntos
Sinais (Psicologia) , Idioma , Tibet , Redação
3.
Food Res Int ; 163: 112255, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36596166

RESUMO

Polysaccharides as a functional prebiotic have numerous activities such as regulating intestinal microorganisms and polysaccharide is one of the functional active components in tea has been known. In this study, we aimed to investigate the physicochemical characteristics of polysaccharides from four kinds of Tibetan teas at simulated digestion stages and the effect on the microbiota of fecal fermentation stages in vitro. The results revealed that Tibetan tea polysaccharides were partially digested during digestion. Additionally, during in vitro fecal microbial fermentation, Tibetan tea polysaccharides can promote the growth of some beneficial bacteria such as Bifidobacterium, Prevotella and Phascolarctobacterium to change the composition of intestinal microorganisms and promote the production of short-chain fatty acids (SCFAs). Finally, a strong correlation was found between the production of SCFAs and microorganisms including Bacteroides, Bifidobacterium and Lachnoclostridium. These results suggest that Tibetan tea polysaccharides could be developed as a prebiotic to regulate human gut microbiota.


Assuntos
Digestão , Polissacarídeos , Humanos , Fermentação , Tibet , Prebióticos , Ácidos Graxos Voláteis , Chá
4.
Food Res Int ; 163: 112275, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36596185

RESUMO

Ophiocordyceps sinensis is a traditional medicinal fungus endemic to the alpine and high-altitude areas of the Qinghai-Tibet plateau. The scarcity of the wild resource has led to increased attention to artificially cultivated O. sinensis. However, little is known about the metabolic differences and the regulatory mechanisms between cultivated and wild O. sinensis. This study exploited untargeted metabolomics and transcriptomics to uncover the differences in accumulated metabolites and expressed genes between wild and cultivated O. sinensis. Metabolomics results revealed that 368 differentially accumulated metabolites were mainly enriched in biosynthesis of amino acids, biosynthesis of plant secondary metabolites and purine nucleotide metabolism. Cultivated O. sinensis contained more amino acids and derivatives, carbohydrates and derivatives, and phenolic acids than wild O. sinensis, whereas the contents of most nucleosides and nucleotides in wild O. sinensis were significantly higher than in cultivated O. sinensis. Transcriptome analysis indicated that 4430 annotated differentially expressed genes were identified between two types. Integrated metabolomics and transcriptomics analyses suggested that IMPDH, AK, ADSS, guaA and GUK genes might be related to the synthesis of purine nucleotides and nucleosides. Our findings will provide a new insight into the molecular basis of metabolic variations of this medicinal fungus.


Assuntos
Cordyceps , Cordyceps/genética , Transcriptoma , Perfilação da Expressão Gênica , Tibet , Metabolômica
5.
Nat Commun ; 14(1): 32, 2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36596797

RESUMO

Despite knowledge of the presence of the Tibetan Plateau (TP) in reorganizing large-scale atmospheric circulation, it remains unclear how surface albedo darkening over TP will impact local glaciers and remote Asian monsoon systems. Here, we use a coupled land-atmosphere global climate model and a glacier model to address these questions. Under a high-emission scenario, TP surface albedo darkening will increase local temperature by 0.24 K by the end of this century. This warming will strengthen the elevated heat pump of TP, increasing South Asian monsoon precipitation while exacerbating the current "South Flood-North Drought" pattern over East Asia. The albedo darkening-induced climate change also leads to an accompanying TP glacier volume loss of 6.9%, which further increases to 25.2% at the equilibrium, with a notable loss in western TP. Our findings emphasize the importance of land-surface change responses in projecting future water resource availability, with important implications for water management policies.


Assuntos
Atmosfera , Água , Tibet , Temperatura
6.
Huan Jing Ke Xue ; 44(1): 323-335, 2023 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-36635820

RESUMO

Using the MOD13A3 NDVI time series from 2000 to 2020, climate date from 1999 to 2020, and land use type data in 2000 and 2020, the spatio-temporal variation in vegetation cover and the driving mechanisms of climate change and human activities to vegetation variation were analyzed based on Theil-Sen Median analysis, the Mann-Kendall significance test, the multi-collinearity test, residual analysis, and relative analysis. The results showed that the vegetation cover exhibited a fluctuating and increasing trend with a magnitude of 0.0016 a-1 in southwest China from 2000 to 2020. The increasing trend of vegetation cover was mostly significant in the Guangxi Hills and Yunnan-Guizhou Plateau and slightly significant in the Tibet Plateau. The vegetation cover had increased in the context of climate change and human activities, with an increasing rate of 0.0010 a-1 and 0.0006 a-1, respectively. The vegetation improvement was mostly dominated by the combination effects of climate change and human activities. The vegetation improvement was dominated by climate change, and the relative role of climate change reached 61.86%. What is more, the vegetation degradation was dominated by human activities, and the relative role of human activities reached 58.39%. Vegetation cover was positively related to minimum temperature, precipitation, maximum temperature, potential evapotranspiration rate, and relative humidity and negatively related to mean temperature, atmosphere pressure, sunshine duration, warmth index, and humidity index. As a whole, the minimum temperature, sunshine duration, and precipitation were the dominant climate factors affecting the vegetation variation in southwest China. Furthermore, the land use and land cover change were significantly related to vegetation variation in southwest China. The implementation of ecological afforestation projects could be beneficial to regional vegetation improvement, whereas the vegetation degradation was mostly conducted by the built-up land expansion.


Assuntos
Condução de Veículo , Humanos , China , Tibet , Atividades Humanas , Mudança Climática , Temperatura , Ecossistema
7.
Huan Jing Ke Xue ; 44(1): 512-519, 2023 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-36635839

RESUMO

Soil microorganisms dominate the biogeochemical cycles of elements in glacier forelands, which continue to expand due to the climate warming. We analyzed the soil microbial functional characteristics among three types of glacier forelands on the Tibetan Plateau: Yulong Glacier (Y), a temperate glacier; Tianshan Urumqi Glacier No.1 (T), a sub-continental glacier; and Laohugou Glacier No.12 (L), a continental glacier. Here, soil microbial functional genes were quantified using quantitative microbial element cycling technology (QMEC). We found that, in the three glacier forelands, the abundances of soil microbial functional genes related to hemicellulose degradation and reductive acetyl-CoA pathway were highest compared with other carbon-related functional genes. The main nitrogen cycling genes were involved in ammonification. The functional genes of the phosphorus cycle and sulfur cycle were related to organic phosphate mineralization and sulfur oxidation. Furthermore, the soils of the temperate glacier foreland with better hydrothermal conditions had the most complex microbial functional gene structure and the highest functional potentials, followed by those of the soils of continental glacier foreland with the driest environment. These significant differences in soil microbial functional genes among the three types of glacier forelands verified the impacts of geographic difference on microbial functional characteristics, as well as providing a basis for the study of soil microbial functions and biogeochemical cycles in glacier forelands.


Assuntos
Camada de Gelo , Microbiologia do Solo , Tibet , Camada de Gelo/química , Solo/química , Enxofre/metabolismo
8.
Huan Jing Ke Xue ; 44(1): 262-271, 2023 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-36635814

RESUMO

In recent years, the ecosystems on the Qinghai-Tibet Plateau (QTP) have been facing a high risk of degradation due to the impacts of climate change and human activities. As one of the important components in river ecosystems, microbial communities can reflect the overall changes in the watershed and are regarded as indicators of the health of river ecosystems. In order to investigate the diversity and composition characteristics of bacterial communities in river ecosystems on the QTP, 65 samples were collected from the Yellow River, Yangtze River, Lancang River, Nujiang River, Yarlung Tsangpo River, and Qaidam Basin on the QTP in July 2021 and were analyzed using 16S rRNA high-throughput sequencing. The results showed that the detected bacterial communities covered 65 phyla and 1311 genera in total. Bacterial communities had high α-diversity indexes across the rivers, indicating that the bacterial richness and diversity in rivers on the QTP were at a high level. Among them, Chao and observed OTUs had significantly negative relationships with SRP/TP. The dominant phyla were Proteobacteria, Bacteroidota, Actinobacteriota, and Cyanobacteria. The dominant classes were γ-proteobacteria, Bacteroidia, and α-proteobacteria. The dominant genera were Flavobacterium and Limnohabitans. The results of principal coordinate analysis and permutational MANOVA suggested significant differences in bacterial community structure among the rivers on the QTP. Canonical correspondence analysis showed that the significant environmental variables associated with the variation in the bacterial communities were physicochemical properties of the river water, including conductivity, pH, dissolved silicon, and dissolved organic carbon, as well as watershed characteristics, including the average normalized differential vegetation index, average slope, cumulative water channel distance, catchment size, proportion of shrub area, and average elevation. Among them, conductivity had the strongest influence on bacteria distribution on the QTP. These results provide a database and information for understanding the composition characteristics of microbial communities on the QTP and identifying environmental factors influencing the diversity of bacteria communities.


Assuntos
Microbiota , Rios , Bactérias/genética , Bacteroidetes , Genes de RNAr , Rios/microbiologia , RNA Ribossômico 16S/genética , Tibet
9.
Sci Rep ; 13(1): 877, 2023 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-36650209

RESUMO

Nitrogen (N) deposition might alleviate degradation of alpine grassland caused by N limitation on the Tibetan Plateau (TP). To determine such limitation and quantify the N-induced N retention in plant, a six-year fertilization experiment with six levels of N addition rates (0, 1, 2, 4, 8 and 16 g N m-2 yr-1) was conducted in the Namco alpine steppe and additional 89 experiments with multi-level N addition were also synthesized worldwide among which 27 sites were on the TP. In general, N addition promoted N retention in plants, and this increasing trend diminished at the critical N rate (Ncr). The maximum N retention capacity (MNRC) of plants at Ncr was strongly correlated with initial aboveground net primary productivity with a slope of 0.02, and the MNRC of grasslands globally ranged from 0.35 to 42.59 g N m-2 yr-1, approximately account for 39% of Ncr. Tibetan alpine grassland had a low average MNRC (2.24 g N m-2 yr-1) with distinct regional characteristic, which was much lower in the western TP (0.80 g N m-2 yr-1) than the eastern TP (4.10 g N m-2 yr-1). Our results inferred 0.33-1.21 Tg N yr-1 (0.22-0.79 g N m-2 yr-1) can be retained and 5.65-20.11 Tg C yr-1 (3.67-13.06 g C m-2 yr-1) can be gained by Tibetan alpine grasslands under current N deposition level. With the aggravation of N deposition, the alpine steppe ecosystem might continuously absorb N and C until N deposition reaches Ncr.


Assuntos
Ecossistema , Pradaria , Tibet , Biomassa , Nitrogênio/metabolismo , Solo , Plantas/metabolismo
10.
PeerJ ; 11: e14556, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36643642

RESUMO

Tibetan pigs, an indigenous pig breed in China, have high overall fat deposition and flavorful and tasty meat. They are thus good models for studying adipogenesis. Few studies have been conducted focusing on expression of lipid regulated genes in different adipose tissues of Tibetan pigs. Therefore, we compared the difference of histomorphology and expression level of lipid regulated genes through qPCR and western blot in subcutaneous fat, perirenal fat, omental adipose tissue, and inguinal fat of Tibetan pigs. Our results showed that the area of subcutaneous adipocytes in Tibetan pigs was smaller, while the other three adipose tissues (perirenal fat, greater omentum fat, inguinal fat) had cell areas of similar size. The gene expression of FABP4, FASN, FABP3, and ME1 in subcutaneous fat was significantly higher than that in perirenal fat. Furthermore, the protein expression of FABP4 was significantly lower in subcutaneous fat than in perirenal fat (p < 0.05), and the expression of FASN was higher in greater omentum fat than in subcutaneous fat (p = 0.084). The difference in adipocyte cell size and expression of lipid-regulated genes in adipose tissues from the various parts of the pig body is likely due to the different cellular lipid metabolic processes. Specially, FABP4 and FASN may be involved in the regulation of fat deposition in different adipose tissues of Tibetan pigs.


Assuntos
Adipócitos , Tecido Adiposo , Suínos/genética , Animais , Tibet , Tecido Adiposo/anatomia & histologia , Adipócitos/metabolismo , Gordura Subcutânea/metabolismo , Lipídeos
11.
Artigo em Inglês | MEDLINE | ID: mdl-36674288

RESUMO

Heatwaves occur frequently in summer, severely harming the natural environment and human society. While a few long-term spatiotemporal heatwave studies have been conducted in China at the grid scale, their shortcomings involve their discrete distribution and poor spatiotemporal continuity. We used daily data from 691 meteorological stations to obtain torridity index (TI) and heatwave index (HWI) datasets (0.01°) in order to evaluate the spatiotemporal distribution of heatwaves in the Chinese mainland for the period of 1990-2019. The results were as follows: (1) The TI values rose but with fluctuations, with the largest increase occurring in North China in July. The areas with hazard levels of medium and above accounted for 22.16% of the total, mainly in the eastern and southern provinces of China, South Tibet, East and South Xinjiang, and Chongqing. (2) The study areas were divided into four categories according to the spatiotemporal distribution of hazards. The "high hazard and rapidly increasing" and "low hazard and continually increasing" areas accounted for 8.71% and 41.33% of the total, respectively. (3) The "ten furnaces" at the top of the provincial capitals were Zhengzhou, Nanchang, Wuhan, Changsha, Shijiazhuang, Nanjing, Hangzhou, Haikou, Chongqing, and Hefei. While the urbanization level and population aging in the developed areas were further increased, the continuously increasing heatwave hazard should be fully considered.


Assuntos
Humanos , Estações do Ano , China/epidemiologia , Cidades , Tibet
13.
Braz. j. biol ; 83: e245862, 2023. graf
Artigo em Inglês | LILACS, VETINDEX | ID: biblio-1339337

RESUMO

Abstract Except for a few stick insects that are economically valuable, most species be considered to be forest pests, so it is extremely important to obtain plant host-use information of more stick insects. In this paper, the plant hosts of three species of stick insects were recorded for the first time. We also discovered these stick insects can feed upon the flowers or leaves of plants. Lopaphus unidentatus (Chen & He, 1995) (Phasmida: Lonchodidae) attacked Hypericum choisianum Wall. ex N. Robson, 1973 (Hypericaceae), Leurophasma dolichocercum Bi, 1995 (Phasmida: Aschiphasmatidae) attacked Antenoron filiforme (Thunb.) Roberty & Vautier, 1964 (Polygonaceae) and Megalophasma granulatum Bi, 1995 (Phasmida: Lonchodidae) attacked Debregeasia orientalis C. J. Chen, 1991 (Urticaceae). Finally, we were lucky enough to also obtain photographs of them mating and feeding.


Resumo Exceto por alguns insetos-pau que são economicamente valiosos, a maioria das espécies pode ser considerada praga florestal, por isso é extremamente importante obter informações sobre o uso de hospedeiros de plantas de mais insetos-pau. Neste artigo, as plantas hospedeiras de três espécies de bicho-pau foram registradas pela primeira vez. Também descobrimos que esses bichos-pau podem se alimentar de flores ou folhas de plantas. Lopaphus unidentatus (Chen & He, 1995) (Phasmida: Lonchodidae) atacou a parede de Hypericum choisianum. ex N. Robson, 1973 (Hypericaceae), Leurophasma dolichocercum Bi, 1995 (Phasmida: Aschiphasmatidae) atacou Antenoron filiforme (Thunb.) Roberty & Vautier, 1964 (Polygonaceae) e Megalophasma granulatum Bi, 1995 (Phasmida: Lonchodidae orientaled) atacou Chen, 1991 (Urticaceae). Finalmente, tivemos a sorte de também obter fotos deles se acasalando e se alimentando.


Assuntos
Animais , Plantas , Insetos , Tibet , Folhas de Planta , Flores
14.
Sci Total Environ ; 862: 160743, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36502968

RESUMO

Magnesium (Mg) plays a crucial role in regulating plant photosynthesis and stress resistance. However, our understanding of plant Mg at the community level remains limited because of lack of systematic investigations. This study, for the first time, comprehensively evaluated community-level Mg content and density, and determined their spatial patterns and driving factors, on the Qinghai-Tibetan Plateau (TP), using data from 680 ecosystems (169 forests, 22 shrublands, 466 grasslands, and 23 deserts). Mg density was 1.01, 2.36, 1.87, and 2.26 g m-2 in leaves, branches, trunks, and roots, respectively. Notably, we generated maps of plant Mg content and density with a 1 km × 1 km resolution based on random forest models. Mg content decreased from northwest to southeast, but Mg density was higher in the east of the plateau, which reflected plant adaptive strategies to the unique radiation, oxygen, and temperature conditions (major driving factors) on the TP. Our findings provide insights into biogeochemical cycling and could facilitate the optimization of remote sensing parameters.


Assuntos
Ecossistema , Magnésio , Tibet , Plantas , Temperatura
15.
Sci Total Environ ; 862: 160888, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36521618

RESUMO

Glacier foreland soils are known to be essential methane (CH4) consumers. However, global warming and increased glacier meltwater have turned some foreland meadows into swamp meadows. The potential impact of this change on the function of foreland soils in methane consumption remains unclear. Therefore, we collected Tibetan glacier foreland soils in the non-melting season from typical microtopography in swamp meadows (hummock and hollow). Three soil moisture conditions (moist, saturated, and submerged) were set by adding glacier runoff water. Soil samples were then incubated in the laboratory for two weeks at 10 °C and 20 °C. About 5 % of 13CH4/12CH4 was added to the incubation bottles, and daily methane concentrations were measured. DNA stable isotope probing (DNA-SIP) and high-throughput sequencing were combined to target the active methanotroph populations. The results showed that type Ia methanotrophs, including Crenothrix, Methylobacter, and an unclassified Methylomonadaceae cluster, actively oxidized methane at 10 °C and 20 °C. There were distinct responses of methanotrophs to soil moisture rises in hummock and hollow soils, resulting in different methane oxidation potentials. In both hummock and hollow soils, the methane oxidation potential was positively correlated with temperature. Furthermore, saturated hummock soils exhibited the highest methane oxidation potential and methanotroph populations, while submerged hollow soils had the lowest. This suggests that the in-situ hummock soils, generally saturated with water, are more essential than in-situ hollows, typically submerged in water, for alleviating the global warming potential of swamp meadows in the Tibetan glacier foreland during the growing season.


Assuntos
Camada de Gelo , Solo , Tibet , Temperatura , Oxirredução , Água , Metano , DNA , Microbiologia do Solo
16.
Sci Total Environ ; 862: 160938, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36526168

RESUMO

Contaminants in high-altitude mountains such as the Tibetan Plateau (TP) have attracted extensive attention due to their potential impact on fragile ecosystems. Rapid development of the economy and society has promoted pollution caused by local traffic emissions in the TP. Among the pollutants emitted by traffic, polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) are of particular concern due to their high toxicity. The TP provides an environment to explore the degree and range of contribution for traffic-induced PAHs and OPAHs. In this study, soils and moss were collected at different altitudes and distances from the G318 highway in the southeast TP. The total concentrations of PAHs (∑16PAHs) and OPAHs (∑6OPAHs) in soils were in the range of 3.29-119 ng/g dry weight (dw) and 0.54-9.65 ng/g dw, respectively. ∑16PAH and ∑6OPAH concentrations decreased logarithmically with increasing distance from traffic. A significantly positive correlation between ∑16PAHs and altitude was found at sampling points closest to traffic. Dominant PAHs constituents in soil and moss included chrysene (CHR), benzo[g,h,i]perylene (BghiP), and benzo[b]fluoranthene (BbF); prevalent OPAH compounds were 9-fluorenone (9-FO) and 9,10-anthraquinone (ATQ). These compounds were related to characteristics of traffic emissions. The multiple diagnosis ratio and correlation analysis showed that exhaust emissions were the main source of the PAHs and OPAHs in the studied environment. PMF modeling quantification of the relative contribution of traffic emissions to PAHs in roadside soils was 45 % on average. The present study characterized the extent and range of traffic-induced PAH and OPAH emissions, providing valuable information for understanding the environmental behaviors and potential risks of traffic-related contaminants in high-altitude areas.


Assuntos
Briófitas , Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Hidrocarbonetos Policíclicos Aromáticos/análise , Tibet , Monitoramento Ambiental , Solo , Ecossistema , Poluentes do Solo/análise
17.
Sci Total Environ ; 858(Pt 3): 159995, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36356782

RESUMO

Ecological regions of medium fragility account for 55 % of China's land. Large-scale afforestation and land reclamation have been carried out in these areas over the past few decades. However, how future climate change poses risks and challenges to them remains unclear. By establishing a multi-algorithm framework combining machine learning algorithms with multi-source dataset, our work predicts Normalized Difference Vegetation Index (NDVI, a proxy for vegetation greenness) and its variations in the 21st century under different climate scenarios. We find that vegetation greening (i.e., NDVI increase) in northern and southwestern China is unstable over four 20-year periods from 2020 to 2100. However, a strikingly prominent greening is expected to occur on the Qinghai-Tibet Plateau until the end of this century. Future warming can not only exacerbate the difficulties of vegetation conservation and restoration in vulnerable ecological regions, also threaten these new croplands, stymieing ambitions to increase crop production in China. Our results underscore the crucible that a warming climate presents to current restoration projects. We highlight the urgency of adapting to climate change to achieve ambitious goals of carbon sequestration and food security in China.


Assuntos
China , Tibet
18.
Sci Total Environ ; 858(Pt 3): 160016, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36368400

RESUMO

In the context of global warming, the plateau lakes generally expand, but some lakes in the southern Tibetan Plateau appear to shrinkage, such as Duoqing Co Lake. We analyzed Duoqing Co which is located on the Yadong-Gulu Rift zone and two surrounding lakes using satellite and meteorological data. Optical and radar images were used to construct a time series of these lakes from 1988 to 2021. By comparing the area changes of surrounding lakes, it is found that Como Chamling Lake has shrunk, while Puma Yum Co Lake has shown an expansion trend. The interference deformation results show that both sides of the Yadong-Gulu Rift zone where the Duoqing Co Lake is located have experienced strong uplift and subsidence, sinking in the east and uplifting in the west. Under the northward compression of the Indian plate, the blocks on both sides of the Yadong-Gulu Rift zone have been relatively displaced. The disappearance of Duoqing Co Lake could be attributed to the existence of leakage channels in the Yadong-Gulu Rift zone. The north-south rift zones of the Tibetan Plateau pass through the Qiangtang Basin, and some lakes in this basin are shrinking, which could be related to the leakage of these rift zones. This work provides a new perspective for studying lake changes on the Tibetan Plateau and is a good reference for studying the lake water cycle on the plateau.


Assuntos
Meteorologia , Uganda , Tibet
19.
Theriogenology ; 197: 116-126, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36502589

RESUMO

In mammals, the testis is the organ with the highest transcriptional activity. After gene transcription, translation, and post-translational protein modification, the transcriptional results are finally presented at the metabolic level. Metabolites not only essential for cell signaling and energy transfer, but also directly influenced by the physiological and pathological changes in tissues and accurately reflect the physiological changes. The fact that the testes are oxygen-deprived organs can explain why Sertoli cells and germ cells may use distinctive metabolic pathways to obtain energy in their different stages of development. Therefore, studying metabolic changes during testis development can better elucidate metabolic profile of the testis, which is essential to revealing characteristic metabolic pathways. The present study applied a widely targeted UPLC-MS/MS-based metabolomics approach with large-scale detection, identification and quantification to investigate the widespread metabolic changes during Tibetan sheep testis development. Firstly, a total of 847 metabolites were detected in the sheep testis, and their changes along with the three testis-development stages were further investigated. The results indicated that those metabolites were clustered into amino acids and their derivatives, carbohydrates and their derivatives, organic acids and their derivatives, benzene and substituted derivatives, alcohols and amines, lipids, nucleotides and their derivatives, bile acids, coenzymes and vitamins, hormones and hormone-related compounds, etc. Among them, the most abundant metabolites in the testis were amino acids and lipid metabolites. The results showed that most of the lipids, carbohydrates with their derivatives, as well as alcohol and amines metabolites were high in sexually immature sheep while organic acids, amino acids and nucleotides showed a continuously increasing trend along with testis development stages. Among them, the content of metabolites with antioxidant effects increased along with testis development, while those related with energy synthesis was downregulated with age. Further correlation analyses of each metabolite-metabolite pair emphasized the cross talk between differential metabolisms across testis development, suggesting a significant correlation between lipids and other metabolites. Finally, based on KEGG pathway analysis, we found that the metabolic pathways in Tibetan sheep testis development were mainly clustered into energy metabolism, gonadal development, and anti-oxidative stress. Reactive oxygen species (ROS) are by-products of normal cellular metabolism and are inevitable during testicular energy metabolism. Thus, the anti-oxidative stress function is a key process in maintaining the normal physiological function of testis. These results contributed to a broader view of the testis metabolome and a comprehensive analysis on metabolomic variation among different testis-development stages, providing a theoretical basis for us to understand the sheep testis metabolic mechanism.


Assuntos
Carneiro Doméstico , Testículo , Masculino , Animais , Ovinos , Testículo/metabolismo , Tibet , Cromatografia Líquida/veterinária , Espectrometria de Massas em Tandem/veterinária , Metaboloma , Aminoácidos/metabolismo , Hormônios/metabolismo , Carboidratos , Lipídeos , Aminas/metabolismo , Nucleotídeos/metabolismo
20.
Environ Pollut ; 317: 120824, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36493938

RESUMO

Atom ratio between 235U and 238U is often used as an indicator of U contamination as the isotopic signature of products generated by the nuclear and military industry significantly vary from the natural isotopic ratio of U. In this study, surface soils and glaciers samples were collected in the Tibetan Plateau (TP) and its surrounding areas and analyzed for U isotopic composition. Results show that the 235U/238U atom ratios in the surface soils of the TP ranges from 0.007122 to 0.007615, with an average value of 0.007378 ± 0.00011; while in the snow/ice dust from high-altitude glaciers it ranges from 0.007254 to 0.007687, with an average value of 0.007345 ± 0.000128. These ratios are slightly higher than the typical crustal value, indicating that the TP was affected by an anthropogenic input of 235U, especially in its northeast and southwest sectors. The variability of our results suggests that the spatial distribution of this contamination is not uniform, pointing to differences in the potential sources and transmission paths of radioactive particles. Combining the knowledge of past tests and activities conducted in the geographic areas around the TP with the knowledge of prevailing winds, we hypothesize that the observed 235U contamination in the TP surface soils and glaciers may have originated mainly from the previous nuclear related activities in surrounding areas (e.g., north Gobi Desert and South Asia). In addition, the horizontal and vertical wind field around the Tibetan Plateau, as well as the atmospheric aerosol optical thickness data also demonstrated the possible transport paths of the radionuclides, that is, originated from in northern Gobi desert and South Asia and reached the TP crossing the Himalayas.


Assuntos
Monitoramento Ambiental , Camada de Gelo , Tibet , Monitoramento Ambiental/métodos , Vento , Radioisótopos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...