SIRT1 Mediates H2S-Ameliorated Diabetes-Associated Cognitive Dysfunction in Rats: Possible Involvement of Inhibiting Hippocampal Endoplasmic Reticulum Stress and Synaptic Dysfunction.

Diabetes-associated cognitive dysfunction (DACD) characterized by hippocampal injury increases the risk of major cerebrovascular events and death. Endoplasmic reticulum (ER) stress and synaptic dysfunction play vital roles in the pathological process. At present, no specific treatment exists for the prevention and/or the therapy of DACD. We have recently reported that hydrogen sulfide (H2S) exhibits therapeutic potential for DACD, but the underlying mechanism has not been fully elucidated. Silent information regulator 1 (SIRT1) has been shown to play a role in regulating the progression of diabetes and is also indispensable for memory formation and cognitive performance. Hence, the present study was performed to explore whether SIRT1 mediates the protective effect of H2S on streptozotocin (STZ)-induced cognitive deficits, an in vivo rat model of DACD, via inhibiting hippocampal ER stress and synaptic dysfunction. The results showed that administration of NaHS (an exogenous H2S donor) increased the expression of SIRT1 in the hippocampus of STZ-induced diabetic rats. Then, results proved that sirtinol, a special blocker of SIRT1, abrogated the inhibition of NaHS on STZ-induced cognitive deficits, as appraised by Morris water maze test, Y-maze test, and Novel object recognition behavioral test. In addition, administration of NaHS eliminated STZ-induced ER stress as evidenced by the decreases in the expressions of ER stress-related proteins including glucose-regulated protein 78, C/EBP homologous protein, and cleaved caspase-12 in the hippocampus, while these effects of NaHS were also reverted by sirtinol. Furthermore, the NaHS-induced up-regulation of hippocampal synapse-related protein (synapsin-1, SYN1) expression in STZ-induced diabetic rats was also abolished by sirtinol. Taken together, these results demonstrated that SIRT1 mediates the protection of H2S against cognitive dysfunction in STZ-diabetic rats partly via inhibiting hippocampal ER stress and synaptic dysfunction.

Characterizing the impact of Three Gorges Dam on the Changjiang (Yangtze River): A story of nitrogen biogeochemical cycling through the lens of nitrogen stable isotopes.

The alterations of nitrogen sources and cycling within the Three Gorges Reservoir (TGR) and downstream the Changjiang were investigated to understand the impacts of the construction of the Three Gorges Dam (TGD) and anthropogenic inputs from the associated watershed. Water samples collected in October 2016 were analyzed for hydrologic parameters, nutrient concentrations, and stable isotopes of nitrate (NO3-), ammonium (NH4+) and particulate matter. Nitrate dual stable isotope values ranged from +5.8‰ to +7.1‰ and -1.9‰ to +0.4‰ for δ15N and δ18O, respectively. δ15N values in particulate nitrogen (PN) ranged from +0.5‰ to +8.5‰, with slightly lower values before the dam. δ15N-NH4+ values ranged between +10.5‰ and +19.4‰, likely reflecting the presence of ammonium assimilation throughout the TGR. The contribution of different nitrogen sources was calculated using a Bayesian mixing model. These sources, including soil organic nitrogen, ammonium fertilizer, and sewage effluent, contributed to elevated DIN concentrations within the TGR (83.2 µM-178.5 µM). The construction of the dam has also likely induced changes in the river environment such as ammonium assimilation in the surface waters and nitrification and/or remineralization within the deep waters of the TGR. Overall, during this investigation period, the TGR acted as a sink of PN (retaining 29%), yet negligibly influenced levels of TDN with ~96.5% of TDN exported to the downstream Changjiang and estuary. It is important to understand the long-term impacts of the TGD on the ecological environment of the Changjiang. This study highlights the influence that anthropogenic nitrogen sources have on the natural biogeochemical cycling within the TGR, showing the urgent need to reduce anthropogenic nitrogen pollution.

BDNF-TrkB pathway mediates antidepressant-like roles of H2 S in diabetic rats via promoting hippocampal autophagy.

Hydrogen sulfide (H2 S) plays antidepressant-like roles in diabetic rats. However, the underlying mechanisms remain unclear. Brain-derived neurotropic factor (BDNF), a neurotrophic factor, plays important regulatory roles in depression by its high-affinity tropomysin-related kinase B (TrkB) receptor. Autophagy also is implicated in modulation of depression. Previous work confirmed the modulatory roles of H2 S in BDNF protein expression and autophagy. Thus, in this study, we explored whether the BDNF-TrkB pathway mediates the antidepressant-like effects of H2 S in diabetic rats and whether this process is achieved via promoting hippocampal autophagy. We demonstrated that H2 S upregulated the expressions of BDNF and p-TrkB proteins in the hippocampus of streptozotocin (STZ)-induced diabetic rats. K252a (an inhibitor of BDNF-TrkB pathway) reversed the antidepressant-like roles of H2 S, as evidenced by the tail suspension, forced swimming, novelty suppressed feeding, and elevated plus-maze tests. Furthermore, K252a abolished H2 S-promoted hippocampal autophagy in diabetic rats, as evidenced by a decrease in the number of autolysosome, downregulation of Beclin-1 (a regulator of autophagy in the early stage of the formation of autophagosomal membranes and its level is positively correlated with autophagic activity) expression, and upregulation of P62 (a substrate of autophagic degradation and its level is inversely correlated with autophagic activity) expression, in the hippocampus of rats co-treated with NaHS and STZ. Taken together, these data indicated that the BDNF-TrkB pathway mediates the antidepressant-like roles of H2 S in diabetic rats by enhancing hippocampal autophagy.

Hypoxia and nutrient dynamics affected by marine aquaculture in a monsoon-regulated tropical coastal lagoon.

The Laoyehai (lagoon) is located at the east coast of Hainan Island in the South China Sea and has been subject to perturbations from human activities, notably marine aquaculture, and has eutrophic surface and hypoxic near-bottom waters. A lack of knowledge of hydrodynamic and biogeochemical processes is a challenge to the sustainable management of lagoon at the ecosystem level in science. Five field campaigns, including three during the southwest monsoon and two in the northeast monsoon periods, were carried out at the Laoyehai in 2008-2011. The aim of this study is to investigate the impacts of dynamic processes of hydrography and human activities on nutrient geochemistry and their relationships to the system eutrophication and hypoxia in the lagoon. In this coastal system, high levels of ammonium relative to nitrate are found, elevated phosphate skews the DIN/DIP relative to the Redfield ratio, and the dissolved silicate concentration is high because of submarine groundwater discharge. The organic fraction in the Laoyehai accounts for a large proportion of the total nutrients associated with the release of wastes from marine aquaculture. The hypoxia of near-bottom waters in the Laoyehai is created and maintained by heterotrophic processes that are fueled by organic matter, which are exacerbated by poor water exchange as a consequence of the geomorphology and weak tidal circulation.

Intrathecal Dexmedetomidine Alleviates Shivering during Cesarean Delivery under Spinal Anesthesia.

Shivering associated with spinal anesthesia during Cesarean delivery is an uncomfortable experience for the parturient, which may also cause adverse effects. In this prospective, randomized, double-blind, placebo-controlled study, we sought to evaluate the effect of intrathecal dexmedetomidine, administered as an adjunct to hyperbaric bupivacaine for Cesarean delivery, on the incidence and severity of shivering associated with spinal anesthesia. Patients undergoing Cesarean delivery were randomly allocated to three groups of 30 patients each. Experimental treatments were added to hyperbaric bupivacaine as follows: Patients in group I (control) were administered isotonic saline. Patients in groups II and III received dexmedetomidine (2.5, 5 µg, respectively), mixed with isotonic saline. Shivering was observed in 11, 10 and 2 patients in groups I, II and III, respectively. The incidence of shivering in group III was significantly lower than that in groups I (p=0.005) and II (p=0.01). The severity of shivering was significantly different between the three groups (p=0.01). There were no significant inter-group differences with respect to mean arterial pressure and heart rate at any time point after administration of intrathecal local anesthesia (p>0.05). Intrathecal dexmedetomidine (5 µg) administered as an adjunct to hyperbaric bupivacaine during Cesarean delivery significantly reduced the incidence and intensity of shivering associated with spinal anesthesia.

Multiple isotopes decipher the nitrogen cycle in the cascade reservoirs and downstream in the middle and lower Yellow River: Insight for reservoir drainage period.

Intensive anthropogenic activities, such as excessive nitrogen input and dam construction, have altered the nitrogen cycle in the global river system. However, the focus on the source, transformation and fate of nitrogen in the Yellow River is still scarce. In this study, the multiple isotopes (δ15N-NO3-, δ18O-NO3-, δ15N-NH4+ and δ15N-PN) were deciphered to explore the nitrogen cycling processes and the driving factors in the thermally stratified cascade reservoirs (Sanmenxia Reservoir: SMXR and Xiaolangdi Reservoir: XLDR) and Lower Yellow River (LYR) during the drainage period of the XLDR. In the SMXR, algal bloom triggered the assimilation process in the upper layer before the SMX Dam, followed by remineralization and subsequent nitrification processes in the lower water layers. The nitrification reaction in the XLDR progressively increased along both longitudinal and vertical directions to the lower layer of the XLD Dam, which was linked to the variation in the water residence time of riverine, transition and lentic zones. The robust nitrification rates in the lower layer of the lentic zone coincided with the substantial depletion of nitrate isotopic composition and enrichment of both δ15N-PN and δ15N-NH4+, indicating the longer water residence time not only promoted the growth of the nitrifying population but also facilitated the remineralization to enhance NH4+ availability. In the LYR, the slight nitrate assimilation, as indicated by nitrate isotopic composition and fractionation models, was the predominant nitrogen transformation process. The Bayesian isotope mixing model results showed that manure and sewage was the dominant nitrate source (50 %) in the middle and lower Yellow River. Notably, the in-reservoir nitrification was a significant nitrate source (27 %) in the XLDR and LYR. Our study deepens the understanding of anthropogenic activities impacting the nitrogen cycle in the river-reservoir system, providing valuable insight into water quality management and nitrogen cycle mechanisms in the Yellow River.

Role of CAST-Drp1 Pathway in Retinal Neuron-Regulated Necrosis in Experimental Glaucoma.

OBJECTIVE: Numerous studies have indicated that excitatory amino acid toxicity, such as glutamate toxicity, is involved in glaucoma. In addition, excessive glutamate can lead to an intracellular calcium overload, resulting in regulated necrosis. Our previous studies have found that the calpastatin (CAST)-calpain pathway plays an important role in retinal neuron-regulated necrosis after glutamate injury. Although inhibition of the calpain pathway can decrease regulated necrosis, necrotic cells remain. It has been suggested that there are other molecules that participate in retinal neuron-regulated necrosis. CAST is an important regulator of dynamin-related protein 1 (Drp1)-mediated mitochondrial defects. Thus, the aim of this study was to determine whether the CAST-Drp1 pathway may be an underlying signaling axis in neuron-regulated necrosis. METHODS: Using cultured retinal neurons and in an in-vivo glaucoma model induced by glutamate overload, members of the CAST-Drp1 pathway were assessed by immunofluorescence, Western blotting, Phos-tagTM SDS-PAGE, and co-immunoprecipitation assays. Moreover, the black and white box test was performed on the rats. RESULTS: We found that more retinal neuron-regulated necrosis and Drp1 activation as well as lower CAST levels were present in the glutamate-induced glaucoma model. Rats with glutamate-induced glaucoma exhibited impaired visual function. We also observed retinal neuron-regulated necrosis and Drp1 activity decreased, and impaired vision recovered after CAST active peptide application, indicating that the CAST-Drp1 pathway plays a critical role in retinal neuron-regulated necrosis and visual function. CONCLUSION: The results of this study indicate that the CAST-Drp1 pathway protects against retinal neuron-regulated necrosis, which may expand the therapeutic targets for the treatment of neurodegenerative disorders involving dysfunction of glutamate metabolism, such as glaucoma.

Nutrient exchanges at the sediment-water interface and the responses to environmental changes in the Yellow Sea and East China Sea.

Release from the sediment is an important nutrient source to the water column of global oceans, especially for marginal seas with active biogeochemical processes. Benthic nutrient biogeochemistry and its responses to environmental changes were investigated in the eastern marginal seas of China using a two-layer diffusion-advection-reaction diagenetic model. Overall, the sediment represented the primary nutrient source with fluxes of ~-342 ± 197, -1.25 ± 0.50, and -114 ± 56 × 108 mol/month for dissolved inorganic nitrogen (DIN), phosphate, and silicate, respectively. This could contribute up to ~42% of nutrients requested by primary production (PP), with a DIN/SiO32-/PO43- molar ratio of 273:91:1, which was higher than that in the overlying water (49:47:1). Future benthic nutrient fluxes were predicted under two environmental change scenarios (increasing and decreasing PP and biogenic silica). Our study may help rebuild nutrient budgets in the future and formulate environmental management policies in marginal seas.

Anthropogenic impacts on nutrient variability in the lower Yellow River.

Excessive nutrient discharges and changes in nutrient ratios caused by global change and anthropogenic activities have been reported in global rivers; however, the actual alterations occurring in the Yellow River environment is too fast to catch up with. From 2001 to 2018, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and dissolved silicon (DSi) concentrations showed decreasing trends in the lower Yellow River throughout the study period. Dissolved organic phosphorus (DOP) concentrations increased since 2009, reaching up to 95% of the total dissolved phosphorus. Annual minimum dissolved organic nitrogen concentrations increased with time. We observed extremely low nutrient concentration events since 2014 in response to the retention effect of large reservoirs; this significantly reduced the downstream water discharge and sediment load and increased phytoplankton uptake. To further analyze the variability of nutrient fluxes, we quantified the fluxes to the Yellow River from natural (runoff, precipitation deposition, and sediment load from the Loess Plateau), anthropogenic (recharged water, fertilizer application, and vegetation coverage), social and industrial (population urbanization, GDP, and sewage effluents) sources. The highest contributions of total nutrient fluxes emptied into the Yellow River was fertilizer losing (44-48%) for DIN, sewage effluents (85-88%) for DIP, and runoff (35-65%) for DSi, respectively. Strictly controlling the amount of fertilizer and improving the application methods, improving sewage treatment technology, and vigorously promoting "green travel" might reduce nutrients emptied into the Yellow River based on the main sources of nutrients. Our study may help policy makers formulate strategies and it is possible to own a better water quality in the Yellow River.

Increases in the seaward river flux of nutrients driven by human migration and land-use changes in the tide-influenced delta.

Most large megacities are located on areas adjacent to tide-influenced deltas. However, contribution of megacities to seaward nutrient fluxes in tide-influenced deltas are poorly quantified in regional and global levels. We analyzed nutrient concentrations and water current data for a large and tide-influenced delta, the Changjiang (Yangtze River) since 1980. Concentrations, species ratios and fluxes of nutrients in tide-influenced delta has been found to differ dramatically from those at upstream. Over the period 2004 to 2015, the seaward nutrient fluxes of dissolved inorganic nitrogen and dissolved silica increased by 5%-10%, but dissolved inorganic phosphorus increased by 15%-20%, in the tide-influenced delta of the Changjiang. Consequently, the DIP/DIN decreases by 11% and DIP/DSi increases by 14% at the river mouth relative to those farther upstream the tidal limit. The legacy and/or recycled contribution accounts for 10%-30% of this increased nutrient flux, hence additional sources are predominantly those involving anthropogenic land-use changes. These findings have implications not only for the Changjiang but also for other riverine systems with respect to management strategy. Nutrient dynamics in tide-influenced deltas near urban areas should receive increased research and policy attention. By not considering nutrient sources in tide-influenced deltas, knowledge of the seaward fluxes and species ratios of nutrients from land sources is incomplete and can be biased, to the point that assessments of their impacts on adjacent marine environments may be inaccurate and mitigation policies therefore ineffective.

[Distribution and Emission of Nitrous Oxide (N2O) in Three Gorges Reservoir and Downstream River].

Nitrous oxide (N2O) is an important greenhouse gas and has a great impact on global warming. Affected by human activities, rivers, and reservoirs have become active sites for N2O production and emission. In Three Gorges Reservoir and the downstream Yangtze River, the concentrations and fluxes of dissolved N2O were investigated in September-October 2009 and October 2016 to identify the factors controlling the distribution of N2O in the reservoir and the effect of damming and reservoir operation on N2O emission from the Yangtze River. The dissolved N2O concentration of the reservoir ranged from 9.74 to 16.36 nmol·L-1 with an average of (12.49±1.75) nmol·L-1 in the surface water (about 0 m) and ranged from 9.99 to 14.00 nmol·L-1 with an average of (11.21±0.91) nmol·L-1 in the bottom water (ranging from 6 m to 103 m). The dissolved N2O in the water column of Three Gorges Reservoir varied little, and no significant difference was noted between the overall N2O concentration in the reservoir and that in the downstream river. A positive correlation was noted between N2O and nitrate (NO3-) (P<0.01), although negative correlations were found between N2O and ammonium (NH4+) (P<0.05) and nitrite (NO2-) (P<0.01) in Three Gorges Reservoir. The surface N2O in the Three Gorges Reservoir was overall saturated, with saturation ranging from 122% to 170% in 2009 and from 114% to 187% in 2016. The mean emission rate of N2O from the surface water was (4.6±2.4) µmol·(m2·d)-1 in 2016 and (16.6±4.9) µmol·(m2·d)-1 in October 2009. The Three Gorges Reservoir is a non-negligible source of atmospheric N2O. No obvious difference was noted between upstream and downstream N2O concentrations, which implies that no degassing emission occurs when water passes through turbines and spillways.

Distribution and emission of N2O in the largest river-reservoir system along the Yellow River.

Rivers and reservoirs are affected by human activities and are sources of the greenhouse gas nitrous oxide (N2O). Concentrations of N2O in the middle and lower reaches of the Yellow River and Xiaolangdi Reservoir, China, were measured in June and December 2017. Fluxes were estimated by boundary layer method to explore their controlling factors, especially the impact of damming and reservoir operation. In the middle and lower reaches of the Yellow River, N2O concentrations in surface waters were 26.65 ±â€¯14.67 nmol L-1 in summer and 21.16 ±â€¯5.35 nmol L-1 in winter. In comparison, the concentrations of N2O in the reservoir were 32.94 ±â€¯17.32 nmol L-1 in summer and 23.73 ±â€¯5.60 nmol L-1 in winter. The longitudinal distribution of N2O along the river exhibited different patterns with surface N2O decreasing downstream towards the dam in summer but increasing in winter. Vertical profiles of N2O concentrations in the reservoir showed an increase with depth in summer but were almost vertically uniform in winter. In winter, N2O that had accumulated in the bottom water in summer was transported to the surface by vertical mixing and released into the atmosphere. Dissolved oxygen (DO), water temperature, and in situ biological production were the main factors affecting the distribution of N2O. The mean emissions rates of N2O from the surface waters were 13.7 ±â€¯8.8 µmol m-2 d-1 in summer and 13.2 ±â€¯7.6 µmol m-2 d-1 in winter. Approximately 1.31 × 106 mol N2O was released from the reservoir surface in 2017, which represents 0.12% of the annual N2O emissions from global reservoirs. The construction of dams increased N2O emission from the lower reaches of the river by 4.53 × 105 mol and 1.22 × 105 mol due to the discharge of the bottom water and the water and sediment regulation, respectively. This study demonstrates that the construction of dams and reservoir operation practices have made the Xiaolangdi Reservoir a key area for N2O emissions.

Geochemical discrimination of bulk organic matter in surface sediments of the Cross River estuary system and adjacent shelf, South East Nigeria (West Africa).

Knowledge of the sources, distribution and fate of organic matter (OM) in estuarine and adjacent shelf sediments are important for the understanding of the global biogeochemical cycles. Bulk organic carbon (C-org), total nitrogen (TN), biogenic silica (BSi), stable carbon (δ13C-org) and nitrogen (δ15N) isotopes, and sediment grain sizes were measured to study the spatial distributions and sources of sediment OM in the Cross River estuary system (CRES) and adjacent shelf. Surface sediments in the CRES were composed of clayey silt and sandy silt, while the adjacent shelf sediments were mainly silty sand. The range of the studied parameters was -28.79‰ to -22.20‰ for δ13C-org, -1.32‰-6.31‰ for δ15N, 6.7-29.2 for C-org/N ratios, 0.08%-0.33% for TN, 0.24‰-0.74‰ for BSi, and 0.47%-5.28% for C-org, and their spatial distributions showed a general decreasing trend in both the terrestrial and estuarine OM from the riverine regions to the adjacent shelf. Based on the three-end-member mixing model using the δ13C and δ15N isotopic values, ~58.01 ±â€¯15.32% of sediment OM are derived from terrestrial sources dominated by C3 vascular plants, while ~26.34 ±â€¯9.71% are attributed to estuarine sources dominated by aquatic macrophytes, and ~15.65 ±â€¯12.37% for marine plankton source. Other sources of OM identified included soils underlain C3 vascular plants and agricultural farms enriched with N, sewage, and petroleum hydrocarbons. The relationship between C-org vs. BSi, and the atomic BSi/Corg ratios suggested that diatoms also play an important role in OM sequestration in surface sediments of the CRES and adjacent shelf. The correlations of the δ13C-org and δ15N isotopic values vs. C-org/N ratios resulted in scatter plots, indicating that the distributions of sediment OM in the CRES and adjacent shelf are influenced by post depositional processes, fixed inorganic N adsorbed on fine-grained sediments, microbial degradation, as well as sediment grain size.

Vascular endothelial growth factor activates neural stem cells through epidermal growth factor receptor signal after spinal cord injury.

AIMS: Neural stem cells (NSCs) in the adult mammalian spinal cord are activated in response to spinal cord injury (SCI); however, mechanisms modulating this process are not clear. Here, we noticed SCI elevated expression of vascular endothelial growth factor (VEGF) and we aimed to validate the roles of VEGF in NSCs activation after SCI and investigated the related signals during the process. METHODS: In vitro we detected whether VEGF promoted spinal cord NSCs proliferation and investigated the involved signals; In vivo, we injected VEGF into rat spinal cord to check the NSCs activation. RESULTS: In vitro, VEGF triggered spinal cord NSCs proliferation and maintained self-renewal. Further investigations demonstrated VEGF transactivated epidermal growth factor receptor (EGFR) through VEGF receptor 2 (VEGFR2) to promote spinal cord NSCs proliferation. In vivo, we injected VEGF into spinal cord by laminectomy to confirm the roles of VEGF-VEGFR2-EGFR signals in NSCs activation. VEGF significantly elevated the number of activated NSCs and increased EGFR phosphorylation. In contrast, intraspinal injection of specific inhibitors targeting EGFR and VEGFR2 decreased NSCs activation after SCI. Our results demonstrate that VEGF-VEGFR2-EGFR axis is important for NSCs activation after SCI, providing new insights into the mechanisms of spinal cord NSCs activation postinjury.

Hypoxia off the Changjiang (Yangtze River) estuary and in the adjacent East China Sea: Quantitative approaches to estimating the tidal impact and nutrient regeneration.

Large areas of hypoxia have been reported off The Changjiang Estuary and in the East China Sea. Five cruises, covering winter, spring, and summer, were carried out from 2007 to 2013 in this region, and in August 2013 (summer), an extensive hypoxic event (11,150km2) was observed, which was characterized by an estimated bulk oxygen depletion of 5.1 million tons. A strong tidal impact was observed associated with the bottom oxygen depletion, with the periodicity of diel variations in dissolved oxygen being 12h (i.e., similar to the tidal cycle). A conservative estimate of nutrient regeneration suggested that during the hypoxic event of August 2013, the amount of regenerated nitrogen (as nitrate) and phosphorus (as dissolved inorganic phosphorus) was 27,000-30,000 tons and 1300-41,000tons, respectively. Estimates of the absolute (bulk) regenerated nutrient fluxes were much greater than the conservative estimates.

Process study of biogeochemical cycling of dissolved inorganic arsenic during spring phytoplankton bloom, southern Yellow Sea.

Previous studies in the southern Yellow Sea (SYS) suggest that large spring phytoplankton blooms (SPBs) have occurred in recent decades. Elevated primary production in the water column can lead to the accumulation and transformation of trace elements. Two field study cruises (including two drifting anchor surveys) were conducted on 12-19 February and from 24 March to 15 April 2009, to investigate the impact of different SPB development periods on the concentrations of total dissolved inorganic arsenic (TDIAs: [TDIAs]=[As(V)]+[As(III)]) and As(III) (arsenite) in the SYS. The distribution of TDIAs in the study area was similar between the two field studies, with concentrations increasing from coastal to offshore areas. High arsenite concentrations and As(III)/TDIAs ratios were found in areas having high concentrations of chlorophyll-a, particularly in the subsurface waters of the central SYS during the drifting surveys, where a significant SPB occurred. Results show that the integrated arsenite concentrations increased at an average transformation rate of 0.53±0.24nmol/L/d within the 15days during the bloom, and data from the anchor drifting surveys indicated that approximately 15.1% of the arsenate in the euphotic zone (~30m depth) was converted to arsenite. In addition, 7.1% of TDIAs was scavenged from the water column by phytoplankton forming the blooms (a factor of 5 higher than expected). A preliminary box model was established to estimate the budget for TDIAs in the SYS in early spring (February to April). This showed that biological scavenging is an important sink for TDIAs, which may promote the transformation and migration of inorganic arsenic species, and thus have a substantial impact on the biogeochemical cycling of this element in the SYS. Depletion of arsenate in the upper waters could lead to arsenate stress, potentially damaging fisheries and the ecosystem.

[Surface Property and Sorption Characteristics of Phosphorus onto Surface Sediments in Sanggou Bay].

Kinetic curves and isotherms were investigated to study the sorption mechanism of phosphorus onto the sediments of Sanggou Bay, together with the surface charge properties of sediments and the forms of phosphorus studied. The results showed that the sorption including a fast process and a slow one, and could be described by a two-compartment first order equation. The thermodynamic isotherms were well fitted with a modified Langmuir equation. The maximum adsorption capacity was larger in summer than in spring, and the smaller particle size was favorable to the sorption. The maximum adsorption capacities (Qm) were 0.0471-0.1230 mg x g(-1), and the zero equilibrium phosphorus concentration (EPC0) of the sediments ranged from 0.0596 mg x L(-1) to 0.1927 mg x L(-1), which indicated that the sediments from Sanggou Bay were sources of phosphorus. Inorganic phosphorus (IP) was the main form of total phosphorus (TP). The contents of exchangeable or loosely absorbed P and Fe-bound P increased significantly in the samples after sorption. The sorption process involved physical sorption and chemical sorption, with the former being the predominant.

Biogeochemistry of bulk organic matter and biogenic elements in surface sediments of the Yangtze River Estuary and adjacent sea.

This study investigated the distribution and roles of total organic carbon (TOC), biogenic silicon (BSi), various forms of nitrogen (N) and phosphorus (P), and the stable carbon isotope (δ(13)C) in surface sediments of the Yangtze River Estuary (YRE) and adjacent sea. Terrestrial input accounted for 12-63% of total organic matter in the study area. The distribution of biogenic elements was affected by the Changjiang Diluted Water, the Jiangsu Coastal Current, human activities, marine biological processes, and the sediment grain size. Potentially bioavailable N and P accounted for an average 79.6% of the total N (TN) and 31.8% of the total P (TP), respectively. The burial fluxes for TOC, BSi, TN and TP were 39.74-2194.32, 17.34-517.48, 5.02-188.85 and 3.10-62.72 µmol cm(-2) yr(-1), respectively. The molar ratios of total N/P (1.2-5.0), Si/P (5.0-14.8) and Fe/P (21-61) indicated that much of the P was sequestered in sediments.

Hypoxia-Induced Epithelial-Mesenchymal Transition Is Involved in Bleomycin-Induced Lung Fibrosis.

Pulmonary fibrosis is a severe disease that contributes to the morbidity and mortality of a number of lung diseases. However, the molecular and cellular mechanisms leading to lung fibrosis are poorly understood. This study investigated the roles of epithelial-mesenchymal transition (EMT) and the associated molecular mechanisms in bleomycin-induced lung fibrosis. The bleomycin-induced fibrosis animal model was established by intratracheal injection of a single dose of bleomycin. Protein expression was measured by Western blot, immunohistochemistry, and immunofluorescence. Typical lesions of lung fibrosis were observed 1 week after bleomycin injection. A progressive increase in MMP-2, S100A4, α-SMA, HIF-1α, ZEB1, CD44, phospho-p44/42 (p-p44/42), and phospho-p38 MAPK (p-p38) protein levels as well as activation of EMT was observed in the lung tissues of bleomycin mice. Hypoxia increased HIF-1α and ZEB1 expression and activated EMT in H358 cells. Also, continuous incubation of cells under mild hypoxic conditions increased CD44, p-p44/42, and p-p38 protein levels in H358 cells, which correlated with the increase in S100A4 expression. In conclusion, bleomycin induces progressive lung fibrosis, which may be associated with activation of EMT. The fibrosis-induced hypoxia may further activate EMT in distal alveoli through a hypoxia-HIF-1α-ZEB1 pathway and promote the differentiation of lung epithelial cells into fibroblasts through phosphorylation of p38 MAPK and Erk1/2 proteins.

[Study on distribution of phosphorus in surface sediments of the Yellow Sea and the East China Sea].

Different phosphorus compositions (TP, IP and OP) were determined in surface sediments of the Yellow Sea (YS) and the East China Sea (ECS),sampled from two cruises between March and June, 2011. The results showed that, contents of TP were from 10.50 micromol x g(-1) to 24.10 micromol x g(-1), IP ranged from 7.14 micromol x g(-1) to 17.10 micromol x g(-1) was the major phosphorus speciation accounting for more than 70% in TP. The percent of IP in TP at most stations was between 50% and 90% , only four stations which lied in the East China Sea with the percent was over 90%. The dominant factors affecting the phosphorus concentration and distribution in surface sediments were anthropogenic activities, sources of input materials, grain size, depositional environments and hydrological conditions. TP burial flux (TPBF) that appeared regional differences was affected by sedimentation rates, porosity and oxygen in bottom water, but TP content and sedimentation rates were crucial factors for TPBF.