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1.
Artigo em Inglês | MEDLINE | ID: mdl-38466065

RESUMO

Objective: This study aimed to explore the effects of geriatric experience training on nurses from multiple primary healthcare units in the context of population aging. The study also evaluated the impact of this training on improving nurses' cognitive abilities in preventing falls/bedside accidents in elderly patients and implementing safe nursing practices to reduce the incidence of falls/bedside accidents. Methods: A total of 302 nurses involved in geriatric care from 18 primary healthcare units in the region were randomly categorized into 2 groups on a 1:1 basis. The control group received regular training on falls/bedside accident prevention for patients, whereas the observation group received additional geriatric experience training along with the regular training. Further, 420 elderly patients who experienced moderate-to-severe falls/bedside accidents between February and July 2022, with a Morse Fall Scale (MFS) score of ≥25 were randomly assigned to either the observation or control group on a 1:1 basis. This study compared the 2 groups in terms of nurses' awareness of falls/bedside accident risks, incidence of falls/bedside accidents in patients and patient satisfaction with fall/bedside accident prevention care. Results: No statistically significant differences were observed (P > .05) between the 2 groups of nurses, except in their awareness of the aging population and the increased risk for falls/bedside accidents in elderly patients. However, the observation group nurses scored higher in other aspects of falls/bedside accident risk awareness after undergoing geriatric experience training (P < .05). The incidence of falls/bedside accidents was significantly lower in the observation group than in the control group (P < .05). Patient satisfaction with falls/bedside accident prevention care was significantly higher in the observation group compared with the control group (P < .05). Conclusion: Geriatric experience training for nurses in multiple primary healthcare units in the region could effectively improve the capabilities of primary hospitals in preventing falls/bedside accidents.

2.
Z Gastroenterol ; 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38657616

RESUMO

RATIONALE: The COVID-19 pandemic caused by the SARS-CoV-2 virus has led to health complications beyond respiratory symptoms, revealing multi-organ involvement, including potential gastrointestinal implications. PATIENT CONCERNS: We present a case of a 40-year-old female without any history of achalasia who developed symptoms of the condition following a confirmed SARS-CoV-2 infection. Unusually, multiple esophageal ulcers were identified, which are not typically associated with achalasia. DIAGNOSIS: Achalasia and esophageal ulcers were confirmed through a series of examinations, including barium swallow, CT scan, and upper endoscopy. Furthermore, immunohistochemical staining of esophageal biopsy specimens revealed the presence of the SARS-CoV-2 spike protein, suggesting direct viral involvement. INTERVENTIONS: The patient was treated with calcium channel blockers and proton pump inhibitors and later underwent a peroral endoscopic myotomy (POEM) procedure following the resolution of her COVID-19 infection. OUTCOME: After the POEM procedure, the patient made a good recovery. LESSONS: This case underscores the potential for SARS-CoV-2 to trigger gastrointestinal complications and emphasizes the need for ongoing patient management and further research into the long-term implications of COVID-19. Despite the single-case nature of this report, it contributes to the expanding understanding of the diverse and multi-systemic impact of COVID-19.

3.
Z Gastroenterol ; 2023 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-37798922

RESUMO

RATIONALE: Non-islet cell tumor hypoglycemia (NICTH) is a paraneoplastic syndrome caused by tumors other than insulinoma that is primarily due to excessive production of insulin-like growth factor-II (IGF-II). The prevalence of NICTH is likely underestimated because of a lack of clinical recognition. PATIENT CONCERNS: A 41-year-old male with massive malignant liver tumors presented with recurrent severe hypoglycemia, weight loss, and liver cirrhosis. DIAGNOSIS: NICTH related to IGF-II produced by hepatocellular carcinoma was diagnosed based on clinical symptoms, biochemical tests, and elevated IGF-II/IGF-I ratio. INTERVENTION: Initial treatment with intravenous glucose and parenteral nutrition showed limited efficacy. Glucocorticoids and recombinant human growth hormone led to progressive improvement in blood glucose levels. OUTCOME: Due to extensive tumor burden and liver failure, surgical resection was not feasible, and the patient ultimately succumbed to refractory hypoglycemia and passed away in two weeks. LESSONS: Early recognition and diagnosis of NICTH are crucial in patients with recurrent hypoglycemia and large tumors. Surgical resection is the preferred treatment option, but supportive care and pharmacological interventions, such as glucocorticoids and growth hormone, can help manage refractory hypoglycemia. Further research is needed to explore novel treatment options, including anti-IGF-I and -IGF-II neutralizing antibodies.

4.
BMC Plant Biol ; 20(1): 159, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32293284

RESUMO

BACKGROUND: In most angiosperms, the inheritance of the mitochondria takes place in a typical maternal manner. However, very less information is available about if the existence of structural variations or not in mitochondrial genomes (mitogenomes) between maternal parents and their progenies. RESULTS: In order to find the answer, a stable rice backcross inbred line (BIL) population was derived from the crosses of Oryza glaberrima/Oryza sativa//Oryza sativa. The current study presents a comparative analysis of the mitogenomes between maternal parents and five BILs. There were recorded universal structural variations such as reversal, translocation, fusion, and fission among the BILs. The repeat-mediated recombination and non-homologous end-joining contributed virtually equal to the rearrangement of mitogenomes. Similarly, the relative order, copy-number, expression level, and RNA-editing rate of mitochondrial genes were also extensively varied among BILs. CONCLUSIONS: These novel findings unraveled an unusual mystery of the maternal inheritance and possible cause for heterogeneity of mitogenomes in rice population. The current piece of work will greatly develop our understanding of the plant nucleo-cytoplasmic interaction and their potential role in plant growth and developmental processes.


Assuntos
Genoma Mitocondrial , Oryza/genética , Edição de RNA , Perfilação da Expressão Gênica , Recombinação Homóloga , Hibridização Genética
5.
Appl Microbiol Biotechnol ; 100(18): 8203-12, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27225476

RESUMO

Anaerobic ammonium oxidation (anammox) as an important nitrogen removal pathway has been investigated in intertidal marshes. However, the rhizosphere-driven anammox process in these ecosystems is largely overlooked so far. In this study, the community dynamics and activities of anammox bacteria in the rhizosphere and non-rhizosphere sediments of salt-marsh grass Spartina alterniflora (a widely distributed plant in estuaries and intertidal ecosystems) were investigated using clone library analysis, quantitative PCR assay, and isotope-tracing technique. Phylogenetic analysis showed that anammox bacterial diversity was higher in the non-rhizosphere sediments (Scalindua and Kuenenia) compared with the rhizosphere zone (only Scalindua genus). Higher abundance of anammox bacteria was detected in the rhizosphere (6.46 × 10(6)-1.56 × 10(7) copies g(-1)), which was about 1.5-fold higher in comparison with that in the non-rhizosphere zone (4.22 × 10(6)-1.12 × 10(7) copies g(-1)). Nitrogen isotope-tracing experiments indicated that the anammox process in the rhizosphere contributed to 12-14 % N2 generation with rates of 0.43-1.58 nmol N g(-1) h(-1), while anammox activity in the non-rhizosphere zone contributed to only 4-7 % N2 production with significantly lower activities (0.28-0.83 nmol N g(-1) h(-1)). Overall, we propose that the rhizosphere microenvironment in intertidal marshes might provide a favorable niche for anammox bacteria and thus plays an important role in nitrogen cycling.


Assuntos
Compostos de Amônio/metabolismo , Bactérias/classificação , Bactérias/metabolismo , Biota , Poaceae/crescimento & desenvolvimento , Rizosfera , Microbiologia do Solo , Marcação por Isótopo , Nitrogênio/metabolismo , Oxirredução , Filogenia , Reação em Cadeia da Polimerase , Análise de Sequência de DNA
6.
Appl Microbiol Biotechnol ; 100(19): 8573-82, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27311565

RESUMO

For the past few decades, human activities have intensively increased the reactive nitrogen enrichment in China's coastal wetlands. Although denitrification is a critical pathway of nitrogen removal, the understanding of denitrifier community dynamics driving denitrification remains limited in the coastal wetlands. In this study, the diversity, abundance, and community composition of nirS-encoding denitrifiers were analyzed to reveal their variations in China's coastal wetlands. Diverse nirS sequences were obtained and more than 98 % of them shared considerable phylogenetic similarity with sequences obtained from aquatic systems (marine/estuarine/coastal sediments and hypoxia sea water). Clone library analysis revealed that the distribution and composition of nirS-harboring denitrifiers had a significant latitudinal differentiation, but without a seasonal shift. Canonical correspondence analysis showed that the community structure of nirS-encoding denitrifiers was significantly related to temperature and ammonium concentration. The nirS gene abundance ranged from 4.3 × 10(5) to 3.7 × 10(7) copies g(-1) dry sediment, with a significant spatial heterogeneity. Among all detected environmental factors, temperature was a key factor affecting not only the nirS gene abundance but also the community structure of nirS-type denitrifiers. Overall, this study significantly enhances our understanding of the structure and dynamics of denitrifying communities in the coastal wetlands of China.


Assuntos
Biota , Desnitrificação , Microbiologia Ambiental , Nitrito Redutases/análise , Filogeografia , Áreas Alagadas , Compostos de Amônio/análise , China , Metagenômica , Nitrito Redutases/genética , Análise de Sequência de DNA , Homologia de Sequência , Temperatura , Água/química
7.
Microb Ecol ; 70(1): 30-40, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25592637

RESUMO

Denitrification plays a critical role in nitrogen removal in estuarine and coastal ecosystems. In this study, the community composition, diversity, abundance, and distribution of cytochrome cd1-type nitrite reductase gene (nirS)-harboring denitrifiers in intertidal sediments of the Yangtze Estuary were analyzed using polymerase chain reaction (PCR)-based clone libraries and quantitative PCR techniques. Clone library analysis showed that the nirS-encoding bacterial biodiversity was significantly higher at the lower salinity sites than at the higher salinity sites. However, there was no significant seasonal difference in the nirS gene diversity between summer and winter. Phylogenetic analysis revealed that the nirS-harboring denitrifier communities at the study area had distinctive spatial heterogeneity along the estuary. At the lower salinity sites, the nirS-harboring bacterial community was co-dominated by clusters III and VII; while at the higher salinity sites, it was dominated by cluster I. Canonical correspondence analysis indicated that the community compositions of nirS-type denitrifiers were significantly correlated with salinity, ammonium, and nitrate. Quantitative PCR results showed that the nirS gene abundance was in the range of 1.01 × 10(6) to 9.00 × 10(7) copies per gram dry sediment, without significant seasonal variation. Among all the environmental factors, the nirS gene abundance was only significantly related to the change of salinity. These results can extend our current knowledge about the composition and dynamics of denitrification microbial community in the estuarine ecosystem.


Assuntos
Biodiversidade , Estuários , Sedimentos Geológicos/microbiologia , Microbiota , Salinidade , Compostos de Amônio/análise , Sequência de Bases , China , Análise por Conglomerados , Desnitrificação , Biblioteca Gênica , Dados de Sequência Molecular , Nitratos/análise , Filogenia , Densidade Demográfica , Reação em Cadeia da Polimerase em Tempo Real , Estações do Ano , Análise de Sequência de DNA
8.
Adv Mater ; 36(24): e2313524, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38453665

RESUMO

Crystallization orientation plays a crucial role in determining the performance and stability of perovskite solar cells (PVSCs), whereas effective strategies for realizing oriented perovskite crystallization is still lacking. Herein, a facile and efficient top-down strategy is reported to manipulate the crystallization orientation via treating perovskite wet film with propylamine chloride (PACl) before annealing. The PA+ ions tend to be adsorbed on the (001) facet of the perovskite surface, resulting in the reduced cleavage energy to induce (001) orientation-dominated growth of perovskite film and then reduce the temperature of phase transition, meanwhile, the penetrating Cl ions further regulate the crystallization process. As-prepared (001)-dominant perovskite films exhibit the ameliorative film homogeneity in terms of vertical and horizontal scale, leading to alleviated lattice mismatch and lowered defect density. The resultant PVSC devices deliver a champion power conversion efficiency (PCE) of 25.07% with enhanced stability, and the unencapsulated PVSC device maintains 95% of its initial PCE after 1000 h of operation at the maximum power point under simulated AM 1.5G illumination.

9.
Zhonghua Zhong Liu Za Zhi ; 35(2): 144-7, 2013 Feb.
Artigo em Zh | MEDLINE | ID: mdl-23714672

RESUMO

OBJECTIVE: To compare the effect of radiofrequency ablation (RFA) combined with transcatheter arterial chemoembolization (TACE) with radiofrequency ablation alone for the treatment of 3 - 5 cm hepatocellular carcinoma (HCC). METHODS: From January 2006 to March 2010, sixty-two HCC patients were randomly treated with RFA combined with TACE (n = 32) or RFA alone (n = 30). This group included the patients who had Child-Pugh class A or B with three or fewer tumors, in which just one tumor size was 3 - 5 cm in diameter, and no evidence of extrahepatic tumor metastasis or macrovascular invasion. The follow up ranged from 9 to 39 months. Survival probabilities were estimated with the Kaplan-Meier method, and differences between survival curves were evaluated with the Log rank test. RESULTS: At the end of the study, the 1-, 2- and 3-year overall survival rates in the combined treatment group were 90.6%, 72%, and 53.1%, respectively, and in the radiofrequency ablation alone group were 83.3%, 56.75%, and 23.3%, respectively. The differences between the survival curves of the two groups were not statistically significant (P = 0.176). The 1-, 2-, and 3-year progress-free survival rates in the combined treatment group were 75.0%, 50.0%, and 34.3%, respectively, and in the radiofrequency ablation alone group were 63.3%, 33.3%, and 16.7%, respectively. The differences between the two groups were statistically significant (P = 0.027). The 1-, 2-, and 3-year local tumor progression rates in the combined treatment group were 12.5%, 18.75%, and 18.75% vs. 16.7%, 30%, and 36.6% in the radiofrequency ablation alone group, with a significant difference between the two groups (P = 0.047). CONCLUSION: Radiofrequency ablation plus TACE is better than radiofrequency ablation alone for the treatment of 3 - 5 cm hepatocellular carcinoma.


Assuntos
Carcinoma Hepatocelular/terapia , Ablação por Cateter , Quimioembolização Terapêutica , Neoplasias Hepáticas/terapia , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma Hepatocelular/patologia , Terapia Combinada , Intervalo Livre de Doença , Epirubicina/administração & dosagem , Feminino , Fluoruracila/administração & dosagem , Seguimentos , Humanos , Neoplasias Hepáticas/patologia , Masculino , Pessoa de Meia-Idade , Taxa de Sobrevida , Carga Tumoral
10.
Genes (Basel) ; 14(7)2023 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-37510315

RESUMO

Plastid genomes (plastomes) of angiosperms are well known for their relative stability in size, structure, and gene content. However, little is known about their heredity and variations in wide crossing. To such an end, the plastomes of five representative rice backcross inbred lines (BILs) developed from crosses of O. glaberrima/O. sativa were analyzed. We found that the size of all plastomes was about 134,580 bp, with a quadripartite structure that included a pair of inverted repeat (IR) regions, a small single-copy (SSC) region and a large single-copy (LSC) region. They contained 76 protein genes, 4 rRNA genes, and 30 tRNA genes. Although their size, structure, and gene content were stable, repeat-mediated recombination, gene expression, and RNA editing were extensively changed between the maternal line and the BILs. These novel discoveries demonstrate that wide crossing causes not only nuclear genomic recombination, but also plastome variation in plants, and that the plastome plays a critical role in coordinating the nuclear-cytoplasmic interaction.


Assuntos
Genomas de Plastídeos , Oryza , Oryza/genética , Genomas de Plastídeos/genética , Citoplasma , Citosol , Genômica
11.
Adv Mater ; 35(3): e2206387, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36349808

RESUMO

Among the emerging photovoltaic technologies, rigid perovskite solar cells (PSCs) have made tremendous development owing to their exceptional power conversion efficiency (PCE) of up to 25.7%. However, the record PCE of flexible PSCs (≈22.4%) still lags far behind their rigid counterparts and their mechanical stabilities are also not satisfactory. Herein, through modifying the interface between perovskite and hole transport layer via pentylammonium acetate (PenAAc) molecule a highly efficient and stable flexible inverted PSC is reported. Through synthetic manipulation of anion and cation, it is shown that the PenA+ and Ac- have strong chemical binding with both acceptor and donor defects of surface-terminating ends on perovskite films. The PenAAc-modified flexible PSCs achieve a record PCE of 23.68% (0.08 cm2 , certified: 23.35%) with a high open-circuit voltage (VOC ) of 1.17 V. Large-area devices (1.0 cm2 ) also realized an exceptional PCE of 21.52%. Moreover, the fabricated devices show excellent stability under mechanical bending, with PCE remaining above 91% of the original PCE even after 5000 bends.

12.
Adv Mater ; 35(49): e2305946, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37547965

RESUMO

Perovskite/organic tandem solar cells (POTSCs) are gaining attention due to their easy fabrication, potential to surpass the S-Q limit, and superior flexibility. However, the low power conversion efficiencies (PCEs) of wide bandgap (Eg) perovskite solar cells (PVSCs) have hindered their development. This work presents a novel and effective mixed-cation passivation strategy (CE) to passivate various types of traps in wide-Eg perovskite. The complementary effect of 4-trifluoro phenethylammonium (CF3 -PEA+ , denoted as CA+ ) and ethylenediammonium (EDA2+ , denoted as EA2+ ) reduces both electron/hole defect densities and non-radiative recombination rate, resulting in a record open-circuit voltage (Voc ) of wide-Eg PVSCs (1.35 V) and a high fill factor (FF) of 83.29%. These improvements lead to a record PCE of 24.47% when applied to fabricated POTSCs, the highest PCE to date. Furthermore, unencapsulated POTSCs exhibit excellent photo and thermal stability, retaining over 90% of their initial PCE after maximum power point (MPP) tracking or exposure to 60 °C for 500 h. These findings imply that the synergic effect of surface passivators is a promising strategy to achieve high-efficiency and stable wide-Eg PVSCs and corresponding POTSCs.

13.
Adv Mater ; 35(12): e2208431, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36585902

RESUMO

The interface and crystallinity of perovskite films play a decisive role in determining the device performance, which is significantly influenced by the bottom hole-transporting material (HTM) of inverted perovskite solar cells (PVSCs). Herein, a simple design strategy of polymer HTMs is reported, which can modulate the wettability and promote the anchoring by introducing pyridine units into the polyarylamine backbone, so as to realize efficient and stable inverted PVSCs. The HTM properties can be effectively modified by varying the linkage sites of pyridine units, and 3,5-linked PTAA-P1 particularly demonstrates a more regulated molecular configuration for interacting with perovskites, leading to highly crystalline perovskite films with uniform back contact and reduced defect density. Dopant-free PTAA-P1-based inverted PVSCs have realized remarkable efficiencies of 24.89% (certified value: 24.50%) for small-area (0.08 cm2 ) as well as 23.12% for large-area (1 cm2 ) devices. Moreover, the unencapsulated device maintains over 93% of its initial efficiency after 800 h of maximum power point tracking under simulated AM 1.5G illumination.

14.
Int J Biol Macromol ; 222(Pt A): 121-131, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36113597

RESUMO

The effect of weakly charged insoluble karaya gum (KG) on zein colloidal nanoparticles (ZKGPs) for stabilizing Pickering emulsions was investigated. Due to weak surface charge, KG could cover the surface of zein particles by hydrogen bonds and weak electrostatic interactions. With the increase in coverage, the zeta potential of ZKGPs changed from positive to negative values close to zero and the average particle size tended to become larger. The closest neutral wettability (89.85°) was achieved when the zein/KG mass ratio was 1:1. The samples prepared with high oil volume fraction (φ = 0.5-0.75) and high particle concentration (1.0-1.3 %, w/v) formed emulsion gels easily and showed higher storage stability. CLSM images also confirmed that ZKGPs could be distributed in the continuous phase to enhance the emulsion network structure. Consequently, weakly charged ZKGPs reduced the emulsification energy barrier and increased the coverage and steric hindrance of particles at the oil/water interface. These findings provide new ideas for the development of stable Pickering emulsions for application in food textural modification as well as encapsulation and delivery of bioactive substances.


Assuntos
Nanopartículas , Zeína , Zeína/química , Emulsões/química , Goma de Karaya , Nanopartículas/química , Tamanho da Partícula
15.
Chemosphere ; 171: 118-125, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28012383

RESUMO

Denitrification is a dominant reactive nitrogen removal pathway in most estuarine and coastal ecosystems, and plays a significant role in regulating N2O release. Although multiple antibiotics residues are widely detected in aquatic environment, combined effects of antibiotics on denitrification remain indistinct. In this work, 5 classes of antibiotics (sulfonamides, chloramphenicols, tetracyclines, macrolides, and fluoroquinolones) were selected to conduct orthogonal experiments in order to explore their combined effects on denitrification. 15N-based denitrification and N2O release rates were determined in the orthogonal experiments, while denitrifying functional genes were examined to illustrate the microbial mechanism of the combined antibiotics effect. Denitrification rates were inhibited by antibiotics treatments, and synergistic inhibition effect was observed for multiple antibiotics exposure. Different classes of antibiotics had different influence on N2O release rates, but multiple antibiotics exposure mostly led to stimulatory effect. Abundances of denitrifying functional genes were inhibited by multiple antibiotics exposure due to the antimicrobial properties, and different inhibition on denitrifiers may be the major mechanism for the variations of N2O release rates. Combined effects of antibiotics on denitrification may lead to nitrate retention and N2O release in estuarine and coastal ecosystems, and consequently cause cascading environmental problems, such as greenhouse effects and hyper-eutrophication.


Assuntos
Antibacterianos/toxicidade , Desnitrificação/efeitos dos fármacos , Sedimentos Geológicos/microbiologia , China , Estuários , Nitratos/análise , Nitrogênio/metabolismo , Óxido Nitroso/análise
16.
Environ Pollut ; 214: 265-272, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27105162

RESUMO

Nitrate overload is an important driver of water pollution in most estuarine and coastal ecosystems, and thus nitrate reduction processes have attracted considerable attention. Antibiotics contamination is also an emerging environmental problem in estuarine and coastal regions as a result of growing production and usage of antibiotics. However, the effects of antibiotics on nitrate reduction remain unclear in these aquatic ecosystems. In this study, continuous-flow experiments were conducted to examine the effects of thiamphenicol (TAP, a common chloramphenicol antibiotic) on nitrate reduction and greenhouse gas N2O release. Functional genes involved in nitrogen transformation were also quantified to explore the microbial mechanisms of the TAP influence. Production of N2 were observed to be inhibited by TAP treatment, which implied the inhibition effect of TAP on nitrate reduction processes. As intermediate products of nitrogen transformation processes, nitrite and N2O were observed to accumulate during the incubation. Different TAP inhibition effects on related functional genes may be the microbial mechanism for the changes of nutrient fluxes, N2 fluxes and N2O release rates. These results indicate that the antibiotics residues in estuarine and coastal ecosystems may contribute to nitrate retention and N2O release, which could be a major factor responsible for eutrophication and greenhouse effects.


Assuntos
Poluentes Atmosféricos/química , Antibacterianos/química , Nitratos/química , Óxido Nitroso/química , Tianfenicol/química , Poluentes Químicos da Água/química , Estuários , Eutrofização , Sedimentos Geológicos/química , Efeito Estufa , Nitritos/química , Oxirredução
17.
Sci Rep ; 6: 21338, 2016 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-26883983

RESUMO

Intertidal marshes are alternately exposed and submerged due to periodic ebb and flood tides. The tidal cycle is important in controlling the biogeochemical processes of these ecosystems. Intertidal sediments are important hotspots of dissimilatory nitrate reduction and interacting nitrogen cycling microorganisms, but the effect of tides on dissimilatory nitrate reduction, including denitrification, anaerobic ammonium oxidation and dissimilatory nitrate reduction to ammonium, remains unexplored in these habitats. Here, we use isotope-tracing and molecular approaches simultaneously to show that both nitrate-reduction activities and associated functional bacterial abundances are enhanced at the sediment-tidal water interface and at the tide-induced groundwater fluctuating layer. This pattern suggests that tidal pumping may sustain dissimilatory nitrate reduction in intertidal zones. The tidal effect is supported further by nutrient profiles, fluctuations in nitrogen components over flood-ebb tidal cycles, and tidal simulation experiments. This study demonstrates the importance of tides in regulating the dynamics of dissimilatory nitrate-reducing pathways and thus provides new insights into the biogeochemical cycles of nitrogen and other elements in intertidal marshes.

18.
Sci Rep ; 5: 15621, 2015 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-26494435

RESUMO

Over the past several decades, human activities have caused substantial enrichment of reactive nitrogen in China's coastal wetlands. Although anaerobic ammonium oxidation (anammox), the process of oxidizing ammonium into dinitrogen gas through the reduction of nitrite, is identified as an important process for removing reactive nitrogen, little is known about the dynamics of anammox and its contribution to nitrogen removal in nitrogen-enriched environments. Here, we examine potential rates of anammox and associate them with bacterial diversity and abundance across the coastal wetlands of China using molecular and isotope tracing techniques. High anammox bacterial diversity was detected in China's coastal wetlands and included Candidatus Scalindua, Kuenenia, Brocadia, and Jettenia. Potential anammox rates were more closely associated with the abundance of anammox bacteria than to their diversity. Among all measured environmental variables, temperature was a key environmental factor, causing a latitudinal distribution of the anammox bacterial community composition, biodiversity and activity along the coastal wetlands of China. Based on nitrogen isotope tracing experiments, anammox was estimated to account for approximately 3.8-10.7% of the total reactive nitrogen removal in the study area. Combined with denitrification, anammox can remove 20.7% of the total external terrigenous inorganic nitrogen annually transported into China's coastal wetland ecosystems.


Assuntos
Compostos de Amônio/química , Nitrogênio/isolamento & purificação , Áreas Alagadas , Anaerobiose , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , China , Oxirredução
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