Effects of landscape modification on coastal sediment nitrogen availability, microbial functional gene abundances and N2O production potential across the tropical-subtropical gradient.

Wetland sediment is an important nitrogen pool and a source of the greenhouse gas nitrous oxide (N2O). Modification of coastal wetland landscape due to plant invasion and aquaculture activities may drastically change this N pool and the related dynamics of N2O. This study measured the sediment properties, N2O production and relevant functional gene abundances in 21 coastal wetlands across five provinces along the tropical-subtropical gradient in China, which all had experienced the same sequence of habitat transformation from native mudflats (MFs) to invasive Spartina alterniflora marshes (SAs) and subsequently to aquaculture ponds (APs). Our results showed that change from MFs to SAs increased the availability of NH4+-N and NO3--N and the abundance of functional genes related to N2O production (amoA, nirK, nosZ Ⅰ, and nosZ Ⅱ), whereas conversion of SAs to APs resulted in the opposite changes. Invasion of MFs by S. alterniflora increased N2O production potential by 127.9%, whereas converting SAs to APs decreased it by 30.4%. Based on structural equation modelling, nitrogen substrate availability and abundance of ammonia oxidizers were the key factors driving the change in sediment N2O production potential in these wetlands. This study revealed the main effect patterns of habitat modification on sediment biogeochemistry and N2O production across a broad geographical and climate gradient. These findings will help large-scale mapping and assessing landscape change effects on sediment properties and greenhouse gas emissions along the coast.

Effects of conversion of coastal marshes to aquaculture ponds on sediment anaerobic CO2 production and emission in a subtropical estuary of China.

The extensive conversion of carbon-rich coastal wetland to aquaculture ponds in the Asian Pacific region has caused significant changes to the sediment properties and carbon cycling. Using field sampling and incubation experiments, the sediment anaerobic CO2 production and CO2 emission flux were compared between a brackish marsh and the nearby constructed aquaculture ponds in the Min River Estuary in southeastern China over a three-year period. Marsh sediment had a higher total carbon and lower C:N ratio than aquaculture pond sediment, suggesting the importance of marsh vegetation in supplying labile organic carbon to the sediment. Conversion to aquaculture ponds significantly decreased sediment anaerobic CO2 production rates by 69.2% compared to the brackish marsh, but increased CO2 emission, turning the CO2 sink (-490.8 ± 42.0 mg m-2 h-1 in brackish marsh) into a source (6.2 ± 3.9 mg m-2 h-1 in aquaculture pond). Clipping the marsh vegetation resulted in the highest CO2 emission flux (382.6 ± 46.7 mg m-2 h-1), highlighting the critical role of marsh vegetation in capturing and sequestering carbon. Sediment anaerobic CO2 production and CO2 uptake (in brackish marsh) and emission (in aquaculture ponds) were highest in the summer, followed by autumn, spring and winter. Redundancy analysis and structural equation modeling showed that the changes of sediment temperature, salinity and total carbon content accounted for more than 50% of the variance in CO2 production and emission. Overall, the results indicate that vegetation clearing was the main cause of change in CO2 production and emission in the land conversion, and marsh replantation should be a primary strategy to mitigate the climate impact of the aquaculture sector.

Conversion of coastal wetlands, riparian wetlands, and peatlands increases greenhouse gas emissions: A global meta-analysis.

Land-use/land-cover change (LULCC) often results in degradation of natural wetlands and affects the dynamics of greenhouse gases (GHGs). However, the magnitude of changes in GHG emissions from wetlands undergoing various LULCC types remains unclear. We conducted a global meta-analysis with a database of 209 sites to examine the effects of LULCC types of constructed wetlands (CWs), croplands (CLs), aquaculture ponds (APs), drained wetlands (DWs), and pastures (PASs) on the variability in CO2 , CH4 , and N2 O emissions from the natural coastal wetlands, riparian wetlands, and peatlands. Our results showed that the natural wetlands were net sinks of atmospheric CO2 and net sources of CH4 and N2 O, exhibiting the capacity to mitigate greenhouse effects due to negative comprehensive global warming potentials (GWPs; -0.9 to -8.7 t CO2 -eq ha-1  year-1 ). Relative to the natural wetlands, all LULCC types (except CWs from coastal wetlands) decreased the net CO2 uptake by 69.7%-456.6%, due to a higher increase in ecosystem respiration relative to slight changes in gross primary production. The CWs and APs significantly increased the CH4 emissions compared to those of the coastal wetlands. All LULCC types associated with the riparian wetlands significantly decreased the CH4 emissions. When the peatlands were converted to the PASs, the CH4 emissions significantly increased. The CLs, as well as DWs from peatlands, significantly increased the N2 O emissions in the natural wetlands. As a result, all LULCC types (except PASs from riparian wetlands) led to remarkably higher GWPs by 65.4%-2,948.8%, compared to those of the natural wetlands. The variability in GHG fluxes with LULCC was mainly sensitive to changes in soil water content, water table, salinity, soil nitrogen content, soil pH, and bulk density. This study highlights the significant role of LULCC in increasing comprehensive GHG emissions from global natural wetlands, and our results are useful for improving future models and manipulative experiments.

Large Spatial Variations in Diffusive CH4 Fluxes from a Subtropical Coastal Reservoir Affected by Sewage Discharge in Southeast China.

Coastal reservoirs are potentially CH4 emission hotspots owing to their biogeochemical role as the sinks of anthropogenic carbon and nutrients. Yet, the fine-scale spatial variations in CH4 concentrations and fluxes in coastal reservoirs remain poorly understood, hampering an accurate determination of reservoir CH4 budgets. In this study, we examined the spatial variability of diffusive CH4 fluxes and their drivers at a subtropical coastal reservoir in southeast China using high spatial resolution measurements of dissolved CH4 concentrations and physicochemical properties of the surface water. Overall, this reservoir acted as a consistent source of atmospheric CH4, with a mean diffusive flux of 16.1 µmol m-2 h-1. The diffusive CH4 flux at the reservoir demonstrated considerable spatial variations, with the coefficients of variation ranging between 199 and 426% over the three seasons. The shallow water zone (comprising 23% of the reservoir area) had a disproportionately high contribution (56%) to the whole-reservoir diffusive CH4 emissions. Moreover, the mean CH4 flux in the sewage-affected sectors was significantly higher than that in the nonsewage-affected sectors. The results of bootstrap analysis further showed that increasing the sample size from 10 to 100 significantly reduced the relative standard deviation of mean diffusive CH4 flux from 73.7 to 3.4%. Our findings highlighted the role of sewage in governing the spatial variations in reservoir CH4 emissions and the importance of high spatial resolution data to improve the reliability of flux estimates for assessing the contribution of reservoirs to the regional and global CH4 budgets.

The importance of the propagule-sediment-tide "power balance" for revegetation at the coastal frontier.

Revegetation of pioneer plants is a critical phase in community establishment for mudflats in seriously degraded coastal wetlands. We tested a hypothesis of the importance of a "power balance" among propagule resilience and sedimentary and tidal disturbances for vegetation reestablishment. Our experiment used three types of propagules (seeds, seedlings, and corms) of native Scirpus species in the fringing flats with similar tidal flows and varying sedimentary intensities in the Yangtze Estuary. Regardless of the initial planting densities, the seed germination rate was extremely low in the field situation. Although the incubated seedlings were planted directly on the bare flat, the wave movement easily flushed the seedlings, even at the site with moderate sedimentary accretion. Failure of the revegetation practice using the seed and seedling materials indicated that the combined "growing and anchoring power" of young seedlings and "stabilizing power" of the sediment were insufficient to withstand the "dislodging power" of the tidal energy. In contrast, the planting approach with underground propagules (corms) proved to be feasible for vegetation establishment at the sites with moderate and low-level sedimentary intensities. The successful practice improved the tipping point of plant survival and tussock formation could be surpassed when the combined growing and anchoring power of seedlings that developed from corms with the stabilizing power of the sediment was greater than the dislodging power of the wave energy. However, at the site with high-level sedimentary intensity, the excessive sediment converted to the burying stress power as seedlings developed from the corms, revealing a burial threshold for seedling survival. The risk of seedling establishment was high when the burying stress power of the sediment far outweighed the combination of the growing power of the seedlings and the sediment removal power of the tidal current and surpassed the tipping point of vegetation die-off. Additionally, we checked the practice cost of the different approaches to ensure a highly cost-effective revegetation planning based on site suitability. This study highlights that understanding of the propagule-sediment-tide power balance offers a tool for improvement of the revegetation and management of site-specific sedimentary and hydrological environments for many degraded coastal ecosystems.

Significant inter-annual fluctuation in CO2 and CH4 diffusive fluxes from subtropical aquaculture ponds: Implications for climate change and carbon emission evaluations.

Aquaculture ponds are potential hotspots for carbon cycling and emission of greenhouse gases (GHGs) like CO2 and CH4, but they are often poorly assessed in the global GHG budget. This study determined the temporal variations of CO2 and CH4 concentrations and diffusive fluxes and their environmental drivers in coastal aquaculture ponds in southeastern China over a five-year period (2017-2021). The findings indicated that CH4 flux from aquaculture ponds fluctuated markedly year-to-year, and CO2 flux varied between positive and negative between years. The coefficient of inter-annual variation of CO2 and CH4 diffusive fluxes was 168% and 127%, respectively, highlighting the importance of long-term observations to improve GHG assessment from aquaculture ponds. In addition to chlorophyll-a and dissolved oxygen as the common environmental drivers, CO2 was further regulated by total dissolved phosphorus and CH4 by dissolved organic carbon. Feed conversion ratio correlated positively with both CO2 and CH4 concentrations and fluxes, showing that unconsumed feeds fueled microbial GHG production. A linear regression based on binned (averaged) monthly CO2 diffusive flux data, calculated from CO2 concentrations, can be used to estimate CH4 diffusive flux with a fair degree of confidence (r2 = 0.66; p < 0.001). This algorithm provides a simple and practical way to assess the total carbon diffusive flux from aquaculture ponds. Overall, this study provides new insights into mitigating the carbon footprint of aquaculture production and assessing the impact of aquaculture ponds on the regional and global scales.

Long-Term Effects of Severe Burns on the Kidneys: Research Advances and Potential Therapeutic Approaches.

Burns are a seriously underestimated form of trauma that not only damage the skin system but also cause various complications, such as acute kidney injury (AKI). Recent clinical studies have shown that the proportion of chronic kidney diseases (CKD) in burn patients after discharge is significantly higher than that in the general population, but the mechanism behind this is controversial. The traditional view is that CKD is associated with hypoperfusion, AKI, sepsis, and drugs administered in the early stages of burns. However, recent studies have shown that burns can cause long-term immune dysfunction, which is a high-risk factor for CKD. This suggests that burns affect the kidneys more than previously recognized. In other words, severe burns are not only an acute injury but also a chronic disease. Neglecting to study long-term kidney function in burn patients also results in a lack of preventive and therapeutic methods being developed. Furthermore, stem cells and their exosomes have shown excellent comprehensive therapeutic properties in the prevention and treatment of CKD, making them increasingly the focus of research attention. Their engineering strategy further improved the therapeutic performance. This review will focus on the research advances in burns on the development of CKD, illustrating the possible mechanism of burn-induced CKD and introducing potential biological treatment options and their engineering strategies.

The circRNA-miRNA-mRNA regulatory network in plasma and peripheral blood mononuclear cells and the potential associations with the pathogenesis of systemic lupus erythematosus.

OBJECTIVES: This study aimed to explore the possible role of plasma and peripheral blood mononuclear cells (PBMCs) circular RNA (circRNA) in systemic lupus erythematosus (SLE). METHOD: Total RNA was extracted from blood plasma samples obtained from 10 patients with SLE and 10 healthy controls and subjected to microarray analysis to define the profile of circRNA expression. The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) amplification was conducted. The overlapped circRNA between PBMCs and plasma was performed, the interactions with microRNAs were predicted, the miRNA target mRNA was predicted, and the GEO database was used. The Gene ontology and pathway analysis was performed. RESULTS: One hundred thirty-one upregulated and 314 significantly downregulated circRNAs were identified in the plasma of patients with SLE by the Fold change criteria (≥ 2.0) and P < 0.05. The qRT-PCR results showed that the expression of has-circRNA-102531, has-circRNA-103984, and has-circRNA-104262 was increased in plasma of SLE, and the expression of has-circRNA-102972, has-circRNA-102006, has-circRNA-104313 was decreased in plasma of SLE. Twenty-eight upregulated circRNAs and 119 downregulated circRNAs were overlapped from PBMCs and plasma, and ubiquitination was enriched. Furthermore, the circRNA-miRNA-mRNA network was constructed in SLE after analyzing dataset GSE61635 from GEO. The circRNA-miRNA-mRNA network comprises 54 circRNAs, 41 miRNAs, and 580 mRNAs. In addition, the TNF signaling pathway and the MAPK pathway were enriched from the mRNA of the miRNA target. CONCLUSION: We first revealed the differentially expressed circRNAs in plasma and PBMCs, and then the circRNA-miRNA-mRNA network was constructed. The network's circRNAs could be a potential diagnostic biomarker and potentially play an important role in the pathogenesis and development of SLE. Key Points • This study analyzed the circRNAs expression profiles combined with the plasma and PBMCs, which provided a comprehensive overview of circRNAs expression patterns in SLE. • The network of the circRNA-miRNA-mRNA in SLE was constructed, which contributes to a better understanding of the pathogenesis and development of SLE.

Impacts of land-use change on carbon dynamics in China's coastal wetlands.

The impact of land-use and land-cover change (LULCC) on ecosystem carbon (C) dynamics has been previously documented at local and global scales, but uncertainty persists for coastal wetlands due to geographical variability and field data limitations. Field-based assessments of plant and soil C contents and stocks of various LULCC types were conducted in nine regions along the coastline of China (21°-40°N). These regions cover natural coastal wetlands (NWs, including salt marshes and mangroves) and former wetlands converted to different LULCC types, including reclaimed wetlands (RWs), dry farmlands (DFs), paddy fields (PFs) and aquaculture ponds (APs). The results showed that LULCC generally decreased the C contents and stocks of the plant-soil system by 29.6 % ± 2.5 % and 40.4 % ± 9.2 %, respectively, while it slightly increased the soil inorganic C contents and stocks. Wetlands converted to APs and RWs lost greater ecosystem organic C stocks (EOC, sum of plants and top 30 cm of soil organic C stocks) than other LULCC types. The annual potential CO2 emissions estimated from EOC loss depended on the LULCC type, with an average emission of 7.92 ± 2.94 Mg CO2-eq ha-1 yr-1. The change rate of EOC in all LULCC types showed a significantly deceasing trend with increasing latitude (p < 0.05). The loss of EOC due to LULCC was larger in mangroves than in salt marshes. The results showed that the response of plant and soil C variables to LULCC was mainly related to differences in plant biomass, median grain size, soil water content and soil NH4+-N content. This study emphasized the importance of LULCC in triggering C loss in natural coastal wetlands, which strengthens the greenhouse effect. We suggest that the current land-based climate models and climate mitigation policies must account for specific land-use types and their associated land management practices to achieve more effective emission reduction.

Conversion of coastal wetland to aquaculture ponds decreased N2O emission: Evidence from a multi-year field study.

Land reclamation is a major threat to the world's coastal wetlands, and it may influence the biogeochemical cycling of nitrogen in coastal regions. Conversion of coastal marshes into aquaculture ponds is common in the Asian Pacific region, but its impacts on the production and emission of nitrogen greenhouse gases remain poorly understood. In this study, we compared N2O emission from a brackish marsh and converted shrimp aquaculture ponds in the Shanyutan wetland, the Min River Estuary in Southeast China over a three-year period. We also measured sediment and porewater properties, relevant functional gene abundance, sediment N2O production potential and denitrification potential in the two habitats. Results indicated that the pond sediment had lower N-substrate availability, lower ammonia oxidation (AOA and comammox Nitrospira amoA), nitrite reduction (nirK and nirS) and nitrous oxide reduction (nosZ Ⅰ and nosZ Ⅱ) gene abundance and lower N2O production and denitrification potentials than in marsh sediments. Consequently, N2O emission fluxes from the aquaculture ponds (range 5.4-251.8 µg m-2 h-1) were significantly lower than those from the marsh (12.6-570.7 µg m-2 h-1). Overall, our results show that conversion from marsh to shrimp aquaculture ponds in the Shanyutan wetland may have diminished nutrient input from the catchment, impacted the N-cycling microbial community and lowered N2O production capacity of the sediment, leading to lower N2O emissions. Better post-harvesting management of pond water and sediment may further mitigate N2O emissions caused by the aquaculture operation.

Identification and verification of vascular cell adhesion protein 1 as an immune-related hub gene associated with the tubulointerstitial injury in diabetic kidney disease.

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease (CKD) and end-stage renal disease (ESRD), but the pathogenesis is not completely understood. Tubulointerstitial injury plays critical roles in the development and progression of DKD. The present study aimed to investigate the profile of tubulointerstitial immune cell infiltration and reveal the underlying mechanisms between tubular cell injury and interstitial inflammation in DKD using bioinformatics strategies. First, xCell analysis identified immune cells displaying significant changes in the DKD tubulointerstitium, including upregulated CD4+ T cells, Th2 cells, CD8+ T cells, M1 macrophages, activated dendritic cells (DCs) and conventional DCs, as well as downregulated Tregs. Second, pyroptosis was identified as the main form of cell death compared with other forms of programmed cell death. Vascular cell adhesion protein 1 (VCAM1) was identified as the top ranked hub gene. The correlation analysis showed that VCAM1 was significantly positively correlated with pyroptosis and infiltrated immune cells in the tubulointerstitium. Upregulation of VCAM1 in the DKD tubulointerstitium was further verified in European Renal cDNA Bank cohort and was observed to negatively correlate with the glomerular filtration rate (GFR). Our in vitro study validated increased VCAM1 expression in HK-2 cells under diabetic conditions, and pyroptosis inhibition by disulfiram decreased VCAM1 expression, inflammatory cytokine release and fibrosis. In conclusion, our study identified upregulated VCAM1 expression in renal tubular cells, which might interact with infiltrated immune cells, thus promoting fibrosis. The FDA-approved drug disulfiram might improve fibrosis in DKD by targeting tubular pyroptosis and VCAM1 expression.

Silencing of Central (Pro)renin Receptor Ameliorates Salt-Induced Renal Injury in Chronic Kidney Disease.

Aims: A high-salt diet can aggravate oxidative stress, and renal fibrosis via the brain and renal renin-angiotensin system (RAS) axis in chronic kidney disease (CKD) rats. (Pro)renin receptor (PRR) plays a role in regulating RAS and oxidative stress locally. However, whether central PRR regulates salt-induced renal injury in CKD remains undefined. Here, we hypothesized that the reduction of central PRR expression could ameliorate central lesions and thereby ameliorate renal injury in high-salt-load CKD rats. Results: We investigated RAS, sympathetic nerve activity, oxidative stress, inflammation, and tissue injury in subfornical organs and kidneys in high-salt-load 5/6 nephrectomy CKD rats after the silencing of central PRR expression by intracerebroventricular lentivirus-RNAi. We found that the sympathetic nerve activity was reduced, and the levels of inflammation and oxidative stress were decreased in both brain and kidney. Renal injury and fibrosis were ameliorated. To explore the mechanism by which central inhibition of PRR expression ameliorates kidney damage, we blocked central MAPK/ERK1/2 and PI3K/Akt signaling pathways as well as angiotensin converting enzyme 1-angiotensin II-angiotensin type 1 receptors (ACE1-Ang II-AT1R) axis. Salt-induced overexpression of renal RAS, inflammation, oxidative stress, and fibrosis in CKD rats were prevented by central blockade of the pathways. Innovation: This study provides new insights into the mechanisms underlying salt-induced kidney damage. Targeting central PRR or PRR-mediated signaling pathway may be a novel strategy for the treatment of CKD. Conclusions: These results suggested that the silencing of central PRR expression ameliorates salt-induced renal injury in CKD through Ang II-dependent and -independent pathways.

Nicotinamide Mononucleotide Attenuates Renal Interstitial Fibrosis After AKI by Suppressing Tubular DNA Damage and Senescence.

Acute kidney injury (AKI) is a worldwide health problem currently lacking therapeutics that directly promote renal repair or prevent the occurrence of chronic fibrosis. DNA damage is a feature of many forms of kidney injury, and targeting DNA damage and repair might be effective strategies for kidney protection in AKI. Boosting nicotinamide adenine dinucleotide (NAD+) levels is thought to have beneficial effects on DNA damage repair and fibrosis in other organs. However, no kidney-related studies of such effects have been performed to date. Here, we have shown that NMN (an NAD+ precursor) administration could significantly reduce tubular cell DNA damage and subsequent cellular senescence induced by hydrogen peroxide and hypoxia in human proximal tubular cells (HK-2 cells). The DNA damage inhibition, antiaging and anti-inflammatory effects of NMN were further confirmed in a unilateral ischemia-reperfusion injury (uIRI) mouse model. Most importantly, the antifibrosis activity of NMN was also shown in ischemic AKI mouse models, regardless of whether NMN was administered in advance or during the recovery phase. Collectively, these results suggest that NMN could significantly inhibit tubular cell DNA damage, senescence and inflammation. NMN administration might be an effective strategy for preventing or treating kidney fibrosis after AKI.

Reclamation-induced tidal restriction increases dissolved carbon and greenhouse gases diffusive fluxes in salt marsh creeks.

Intertidal creeks play an important role in transporting nutrients between coastal ecosystems and ocean. Reclamation is a predominant anthropogenic disturbance in coastal regions; however, the influence of reclamation on carbon and nitrogen species and greenhouse gas (GHG) fluxes in creek remains unclear. In a subtropical salt marsh of eastern China, the seasonal patterns of dissolved carbon (DOC, DIC, CO2, and CH4) and inorganic nitrogen (NH4+-N, NO2--N, and NO3--N and N2O) species, and the diffusive fluxes of CO2, CH4, and N2O, were compared between the natural tidal creeks and the reclaimed creeks. Due to notably changed hydrological and biological conditions in the reclaimed creeks, concentrations of all dissolved carbon species, NH4+-N and NO2--N increased significantly by 60.2-288.2%, while NO3--N and N2O decreased slightly, compared to the natural tidal creeks. DIC and NO3--N were the primary components of the total dissolved carbon and inorganic nitrogen in both creek types; however, their proportions decreased as a result of elevated DOC, CO2, CH4, NH4+-N, and NO2--N following reclamation. Significantly higher global warming potential (0.58 ± 0.15 g CO2-eq m-2 d-1) was found in the reclaimed creeks, making them hotspot of greenhouse effects, compared to the natural tidal creeks. Our results indicated that changes in flow velocity, salinity, Chlorophyll a, and pH were the main factors controlling the dissolved carbon and nitrogen and consequent GHG emissions, due to reclamation. This study is helpful in understanding of carbon and nitrogen sink-source shifts resulting from land use changes in coastal wetlands.

Impact of diabetes mellitus on short-term prognosis, length of stay, and costs in patients with acute kidney injury: A nationwide survey in China.

BACKGROUND: International data suggest that people with diabetes mellitus (DM) are at increased risk for worse acute kidney injury (AKI) outcomes; however, the data in China are limited. Therefore, this study aimed to describe the association of DM with short-term prognosis, length of stay, and expenditure in patients with AKI. METHODS: This study was based on the 2013 nationwide survey in China. According to the 2012 Kidney Disease: Improving Global Outcomes (KDIGO) and expanded criteria of AKI, 7604 patients with AKI were identified, and 1404 and 6200 patients were with and without DM, respectively. Clinical characteristics, outcomes, length of stay, and costs of these patients were compared. Multivariate regression analyses were conducted to evaluate the association of DM with mortality, failed renal recovery, length of stay, and costs. RESULTS: Patients with AKI and DM were older, had higher male preponderance (61.9%), presented with more comorbidities, and had higher serum creatinine levels compared with those without DM. An apparent increase in all-cause in-hospital mortality, length of stay, and costs was found in patients with DM. DM was not independently associated with failed renal recovery (adjusted OR (95%CI): 1.08 (0.94-1.25)) and in-hospital mortality (adjusted OR (95%): 1.16 (0.95-1.41)) in multivariate models. However, the diabetic status was positively associated with the length of stay (ß = 0.06, p<0.05) and hospital expenditure (ß = 0.10, p<0.01) in hospital after adjusting for possible confounders. CONCLUSION: In hospitalized AKI patients, DM (vs. no DM) is independently associated with longer length of stay and greater costs, but is not associated with an increased risk for failed renal recovery and in-hospital mortality.

Large variations in indirect N2O emission factors (EF5) from coastal aquaculture systems in China from plot to regional scales.

Aquaculture ponds are important anthropogenic sources of nitrous oxide (N2O). Direct N2O emissions arising from feed application to ponds have been widely investigated, but indirect emissions from N2O production from residual feeds in pond water are much less understood and characterized to refine the IPCC emission factor. In this study, we determined the concentrations and spatiotemporal variations of dissolved N2O and NO3--N in situ in three aquaculture ponds at the Min River Estuary in southeastern China during the culture period over two years, and calculated the indirect N2O emission factor (EF5) for aquaculture ponds using the N2O-N/NO3--N mass ratio methodology. Our results indicated that the EF5 values in the ponds over the culture period ranged between 0.0007 and 0.0543, with a clear seasonal pattern which closely followed that of the DOC:NO3-N ratio. We also observed significant spatial variations in EF5 among the three ponds, which could be attributed to the difference in feed conversion rate. In addition, we assessed the EF5 values from aquaculture ponds in five regions of the Chinese coastline across the latitudinal gradient from the tropical to the temperate zones. The average EF5 value from aquaculture ponds across the five coastal regions was 0.0093±0.0024, which was approximately 3.7 times of the IPCC default value for rivers and estuaries (0.0025). Moreover, the EF5 values demonstrated considerable spatial variations across these coastal regions with a coefficient of variation of 59%, which were largely related to the difference in water salinity. Our findings filled a key knowledge gap about the indirect N2O emission factor from aquaculture ponds, and provided field evidence for the refinement of EF5 value currently adopted by IPCC in the national greenhouse gas inventory.

A pH-Responsive System Based on Fluorescence Enhanced Gold Nanoparticles for Renal Targeting Drug Delivery and Fibrosis Therapy.

BACKGROUND: Stimuli-responsive gold nano-assemblies have attracted attention as drug delivery systems in the biomedical field. However, there are challenges achieving targeted delivery and controllable drug release for specific diseases. MATERIALS AND METHODS: In this study, a glutathione (GSH)-modified fluorescent gold nanoparticle termed AuLA-GSH was prepared and a Co2+-induced self-assembly drug delivery platform termed AuLA-GSH-Co was constructed. Both the pH-responsive character and drug loading behavior of AuLA-GSH-Co were studied in vitro. Kidney-targeting capability was investigated in vitro and in vivo. Finally, the anti-fibrosis efficiency of AuLA-GSH-Co in a mouse model of unilateral ureteral obstruction (UUO) was explored. RESULTS: AuLA-GSH-Co was sensitive to pH changes and released Co2+ in acidic conditions, allowing it to have controllable drug release abilities. AuLA-GSH-Co was found to improve cellular uptake of Co2+ ions compared to CoCl2 in vitro. AuLA-GSH exhibited specific renal targeting and prolonged renal retention time with low non-specific accumulation in vivo. Moreover, the anti-fibrosis efficiency of AuLA-GSH-Co was higher compared to CoCl2 in a mouse model of unilateral ureteral obstruction (UUO). CONCLUSION: AuLA-GSH-Co could greatly enhance drug delivery efficiency with renal targeting capability and obviously relieve renal fibrosis, providing a promising strategy for renal fibrosis therapy.

Association of acute kidney injury and clinical outcomes in patients with COVID-19 in Shenzhen, China: a retrospective cohort study.

BACKGROUND: Acute kidney injury (AKI) was found in some patients with COVID-19 pneumonia and accompanied with poor outcomes. The objective of this study was to investigate the association of AKI with clinical outcomes in COVID-19 patients. METHODS: In this cohort study, we reviewed electronic medical data from patients with COVID-19 in Shenzhen from January 11 to February 19, 2020. Clinical features and clinical outcomes in COVID-19 patients with and without AKI were analyzed. Further, we evaluated the association between AKI development and clinical outcomes. RESULTS: In this study, 9.6% patients developed AKI during hospitalization. Those with AKI presented older age, severer pneumonia, more comorbidity and lower lymphocyte count. Totally, more patients (77.5%) had primary composite outcomes (intensive care unit (ICU) admission, use of high-flow nasal cannula (HFNC) and mechanical ventilation) in AKI group compared to non-AKI group (2.9%) during the observation period. The median length of stay (LOS) and ICU stay were longer among those with AKI. After adjusted for related covariates, AKI development was independently correlated with LOS (ß (95% CI): 9.16 (3.87-14.46)), rather than primary outcomes (HR (95% CI): 1.34 (0.56-3.21)) in COVID-19 patients. CONCLUSIONS: The development of AKI was not one of the reasons for ICU admission, use of HFNC and mechanical ventilation, but a kind of manifestation of severe illness in COVID-19 hospitalized patients.

Sea-level rise will reduce net CO2 uptake in subtropical coastal marshes.

Coastal marshes have a significant capacity to sequester carbon; however, sea-level rise (SLR) is expected to result in prolonged flooding and saltwater intrusion in coastal regions. To explore the effects of SLR projections on net CO2 uptake in coastal marshes, we conducted a "double-check" investigation, including the eddy covariance (EC) measurements of the CO2 fluxes in subtropical coastal marshes along inundation and salinity gradients, in combination with a mesocosm experiment for analyzing CO2 flux components under waterlogging and increased salinity conditions. During the same measurement periods, the net ecosystem CO2 exchange (NEEEC based on the EC dataset) in an oligohaline marsh was higher than that in a low-elevation mesohaline marsh, whereas the NEEEC was lower than that in a high-elevation freshwater marsh. The declines in NEEEC between the marshes could be attributed to a greater decrease in gross primary production relative to ecosystem respiration. Waterlogging slightly increased the NEEms (NEE based on the mesocosms) because of inhibited soil respiration and slight changes in plant photosynthesis and shoot respiration. However, the NEEms measured during the drainage period decreased significantly due to the stimulated soil respiration. The NEEms decreased with increasing salinity (except under mild salinity), and waterlogging exacerbated the adverse impacts of salinity. The amplificatory effect of decreases in both leaf photosynthesis and growth under hydrological stresses contributed more to reduce the NEEms than to respiratory effluxes. Both waterlogging and increased salinity reduced the root biomass, soil microbial biomass, and activities of assayed soil enzymes (except for cellulase under waterlogging conditions), leading to limited soil respiration. The declines in plant growth, photosynthesis, and soil respiration could also be attributed to the decrease in soil nutrients under waterlogging and increased salinity conditions. We propose that the coupling of SLR-driven hydrological effects lowers the capacity of CO2 uptake in subtropical coastal marshes.

[Nutrient Distribution of Overlying Water in Tidal Marshes in Five Estuaries and Bays of the Fuzhou Region in Autumn].

Overlying water from the tidal marshes in five estuaries and bays, namely, Xinghua Bay (Fuzhou Part), Fuqing Bay, Luoyuan Bay, Minjiang River Estuary, and Aojiang River Estuary of the Fuzhou region were collected in autumn of 2015, and the nitrogen and phosphorus nutrient concentration and other physical and chemical indicators of the overlying water were measured to discuss the reasons for the differences in the nutrient concentration of the overlying water in tidal marsh wetlands in different bays and estuaries. There were significant differences in the nitrogen and phosphorus nutrient concentrations of the overlying waters of the tidal marshes in the different bays and estuaries (P<0.05). The concentrations of nitrogen and phosphorus in Fuqing Bay were relatively high, while Xinghua Bay had the lowest nitrogen nutrient concentration and Aojiang River Estuary had the lowest phosphorus nutrient concentration. The nutrient concentration of the overlying water in Fuqing Bay is mainly affected by regional aquaculture, land-source pollution, and topography, while that in Xinghua Bay is mainly affected by tides. The vegetation type had an effect on the nutrient concentration of the overlying water in the wetlands. The concentration of nitrogenous nutrients in the overlying water of the marsh wetland in the Suaeda australis community was relatively high, while the nitrogen and phosphorus nutrient concentrations in the overlying water of the Spartina alterniflora community wetland was relatively low; the concentrations of nutrients in the overlying water of different plant communities in the same bay or estuary marsh wetland were different, and the relationships were complex. Tides, surface runoff, plant communities, topography, and human activities all had an important impact on the nutrient concentrations in the overlying waters of the bay and estuary wetlands.