Acidification Offset Warming-Induced Increase in N2O Production in Estuarine and Coastal Sediments.

Global warming and acidification, induced by a substantial increase in anthropogenic CO2 emissions, are expected to have profound impacts on biogeochemical cycles. However, underlying mechanisms of nitrous oxide (N2O) production in estuarine and coastal sediments remain rarely constrained under warming and acidification. Here, the responses of sediment N2O production pathways to warming and acidification were examined using a series of anoxic incubation experiments. Denitrification and N2O production were largely stimulated by the warming, while N2O production decreased under the acidification as well as the denitrification rate and electron transfer efficiency. Compared to warming alone, the combination of warming and acidification decreased N2O production by 26 ± 4%, which was mainly attributed to the decline of the N2O yield by fungal denitrification. Fungal denitrification was mainly responsible for N2O production under the warming condition, while bacterial denitrification predominated N2O production under the acidification condition. The reduced site preference of N2O under acidification reflects that the dominant pathways of N2O production were likely shifted from fungal to bacterial denitrification. In addition, acidification decreased the diversity and abundance of nirS-type denitrifiers, which were the keystone taxa mediating the low N2O production. Collectively, acidification can decrease sediment N2O yield through shifting the responsible production pathways, partly counteracting the warming-induced increase in N2O emissions, further reducing the positive climate warming feedback loop.

Soliton interaction in a MXene-based mode-locked fiber laser.

MXenes are a class of two-dimensional layered structure ternary metal carbide or/and nitride materials. Recently, the MXene V2CTx has demonstrated excellent long-term stability, strong saturable absorption, and fast optical-switching capability, used to generate Q-switched and ultrashort pulsed lasers. However, bound-state fiber lasers based on V2CTx have not been reported yet. In this study, V2CTx is combined with a D-shaped fiber to form a saturable absorber device, whose modulation depth is measured to be 1.6%. By inserting the saturable absorber into an Er-doped fiber laser, bound states with different soliton separation and munbers are successfully obtained. Additionally, bound states with a compound soliton structure, such as the (2 + 2)- and (2 + 1)-type, are also realized. Our findings show that V2CTx can be developed as an efficient ultrafast photonics candidate to further understand the complex nonlinear dynamics of bound-state pulses in fiber lasers.

Limonene anti-TMV activity and its mode of action.

The main component of orange peel essential oil is limonene. Limonene is a natural active monoterpene with multiple functions, such as antibacterial, antiseptic and antitumor activity, and has important development value in agriculture. This study found that limonene exhibited excellent anti-tobacco mosaic virus (TMV) bioactivity, with results showing that its protection activity, inactivation activity, and curative activity at 800 µg/mL were 84.93%, 59.28%, and 58.89%, respectively-significantly higher than those of chito-oligosaccharides. A direct effect of limonene on TMV particles was not observed, but limonene triggered the hypersensitive response (HR) in tobacco. Further determination of the induction activity of limonene against TMV demonstrated that it displayed good induction activity at 800 µg/mL, with a value of 60.59%. The results of physiological and biochemical experiments showed that at different treatment days, 800 µg/mL limonene induced the enhancement of defense enzymes activity in tobacco, including of SOD, CAT, POD, and PAL, which respectively increased by 3.2, 4.67, 4.12, and 2.33 times compared with the control (POD and SOD activities reached highest on the seventh day, and PAL and CAT activities reached highest on the fifth day). Limonene also enhanced the relative expression levels of pathogenesis related (PR) genes, including NPR1, PR1, and PR5, which were upregulated 3.84-fold, 1.86-fold and 1.71-fold, respectively. Limonene induced the accumulation of salicylic acid (SA), and increased the relative expression levels of genes related to SA biosynthesis (PAL) and reactive oxygen species (ROS) burst (RBOHB), which respectively increased by 2.76 times and 4.23 times higher than the control. Systemic acquired resistance (SAR) is an important plant immune defense against pathogen infection. The observed accumulation of SA, the enhancement of defense enzymes activity and the high-level expression of defense-related genes suggested that limonene may induce resistance to TMV in tobacco by activating SAR mediated by the SA signaling pathway. Furthermore, the experimental results demonstrated that the expression level of the chlorophyll biosynthesis gene POR1 was increased 1.72-fold compared to the control in tobacco treated with 800 µg/mL limonene, indicating that limonene treatment may increase chlorophyll content in tobacco. The results of pot experiment showed that 800 µg/mL limonene induced plant resistance against Sclerotinia sclerotiorum (33.33%), Phytophthora capsici (54.55%), Botrytis cinerea (50.00%). The bioassay results indicated that limonene provided broad-spectrum and long-lasting resistance to pathogen infection. Therefore, limonene has good development and utilization value, and is expected to be developed into a new botanical-derived anti-virus agent and plant immunity activator in addition to insecticides and fungicides.

Ps-Pt nanozyme-based synergistic signal amplification biosensor for highly sensitive colorimetric detection of protein.

Immunosorbent assay is one of the most popular immunological screening techniques which has been widely used for the clinical diagnosis of alpha-fetoprotein (AFP). While traditional immunosorbent assay (ELISA) suffers from low detection sensitivity due to its low intensity of colorimetric signal. To improve the sensitivity of AFP detection, we developed a new and sensitive immunocolorimetric biosensor by combining Ps-Pt nanozyme with terminal deoxynucleotidyl transferase (TdT)-mediated polymerization reaction. The determination of AFP was achieved by measuring the visual color intensity produced by the catalytic oxidation reaction of the 3,3',5,5'-tetramethylbenzidine (TMB) solution with Ps-Pt and horseradish peroxidase (HRP). Owing to the synergistic catalysis of Ps-Pt and horseradish peroxidase HRP enriched in polymerized amplification products, this biosensor exhibited a significant color change within 25 s in the presence of 10-500 pg/mL AFP. This proposed method allowed for the specific detection of AFP with a detection limit of 4.30 pg/mL and even 10 pg/mL target protein could be distinguished clearly by visual observation. Furthermore, this biosensor could be applied to analysis of AFP in the complex sample and could be easily extended to the detection of other proteins.

Three-Dimensional PLGA Nanofiber-Based Microchip for High-Efficiency Cancer Cell Capture.

A 3D network capture substrate based on poly(lactic-co-glycolic acid) (PLGA) nanofibers was studied and successfully used for high-efficiency cancer cell capture. The arc-shaped glass micropillars were prepared by chemical wet etching and soft lithography. PLGA nanofibers were coupled with micropillars by electrospinning. Given the size effect of the microcolumn and PLGA nanofibers, a three-dimensional of micro-nanometer spatial network was prepared to form a network cell trapping substrate. After the modification of a specific anti-EpCAM antibody, MCF-7 cancer cells were captured successfully with a capture efficiency of 91%. Compared with the substrate composed of 2D nanofibers or nanoparticles, the developed 3D structure based on microcolumns and nanofibers had a greater contact probability between cells and the capture substrate, leading to a high capture efficiency. Cell capture based on this method can provide technical support for rare cells in peripheral blood detection, such as circulating tumor cells and circulating fetal nucleated red cells.

Preparation and characterization of vaccarin, hypaphorine and chitosan nanoparticles and their promoting effects on chronic wounds healing.

Chronic wounds have become an important factor hindering human health, affecting tens of millions of people worldwide, especially diabetic wounds. Based on the antibacterial properties of chitosan, the angiogenesis promoting effect of vaccarin (VAC) and the anti-inflammatory effect of hypaphorine (HYP), nanoparticles with high bioavailability were prepared. VAC, HYP and chitosan nanoparticles (VAC + HYP-NPS) were used to the treatment of chronic wounds. Transmission electron microscopy (TEM) images showed the nanoparticles were spherical. ZetaPALS showed the potential of nanoparticles were -12.8 ± 5.53 mV and the size were 166.8 ± 29.95 nm. Methyl thiazolyl tetrazolium (MTT) assay showed that VAC + HYP-NPS had no toxicity and the biocompatibility was satisfactory. In the treatment of chronic wounds in diabetic rats, VAC + HYP-NPS significantly promoted the re-epithelialization of chronic wounds and accelerated the healing of chronic wounds. In the process of chronic wounds healing, VAC + HYP-NPS played the antibacterial effect of chitosan, the angiogenic effect of VAC and the anti-inflammatory effect of HYP, and finally promoted the chronic wounds healing. Overall, the developed VAC + HYP-NPS have potential application in chronic wounds healing. In view of the complexity of the causes of chronic wounds, multi-target drug administration may be an effective way to treat chronic wounds.

Nitrous oxide emissions from subtropical estuaries: Insights for environmental controls and implications.

Estuaries are expected to contribute large nitrous oxide (N2O) emissions, however the environmental controls and implications of N2O emissions have not been well understood. Here we investigated water N2O concentrations, fluxes and sources in wet and dry seasons for 2019-2020 in five subtropical estuaries spanning hydrologic characteristics and nitrogen concentrations gradient. Water dissolved N2O concentrations and fluxes were in a range of 15.8-84.9 nmol L-1 and 0.66-22.2 µg m-2 h-1, respectively. These studied estuaries were oversaturated in N2O, with the saturations of 118-615%. Water dissolved N2O concentrations, saturations and fluxes increased significantly as nitrogen concentrations increase, whereas they did not differ significantly between the wet and dry seasons. Water N2O emissions, however, were also lower in the estuaries characterized by large discharge and water flow. N2O saturations and fluxes were determined directly by water nitrogen and oxygen concentrations and more indirectly by water temperature and velocity. The δ15N-N2O and site preference-N2O varied respectively from 2.86 to 11.31‰ and from 1.58 to 11.72‰, which overlapped the values between nitrification and denitrification. Nitrification and denitrification were responsible for 18.7-38.1% and 61.9-81.3% of N2O emissions, respectively. Indirect N2O emission factors were 0.08-0.14% and decreased with increasing total nitrogen concentrations. It is estimated that water N2O emissions in CO2 equiv could offset approximately 4.9% of average CO2 sink of China estuaries. Therefore, these results suggest that nitrogen concentrations and hydrologic characteristics together modify N2O emissions and that estuaries may be the important contributors to N2O emissions.

Disproportionate variations in denitrification and anaerobic ammonium oxidation across freshwater-oligohaline wetlands in Min River Estuary, Southeast China.

Spatial and temporal variations in soil denitrification and anaerobic ammonium oxidation (anammox) across the freshwater-oligohaline wetlands in subtropical estuary have not been well understood. In this study, continuous-flow soil core incubation combined with nitrogen isotope tracer was used to determine denitrification and anammox rates across freshwater-oligohaline tidal wetlands in Min River Estuary, Southeast China. Areal rates of denitrification and anammox varied from 3.89 to 19.0 µmol m-2 h-1 and from 0.15 to 1.11 µmol m-2 h-1, respectively, across these wetlands and throughout sampling months. Denitrification rates were higher in warm months (July, September) than in cool months (November, January), whereas anammox did not vary significantly across the sampling months. Average denitrification rates throughout the sampling months were higher in freshwater than in oligohaline wetlands, while anammox rates did not vary among the wetlands. Relative contribution of anammox (Ra) to N2 production (including denitrification and anammox) varied from 1.03 to 18.3% across the sampling months and wetlands. Denitrification rates differed significantly across the wetlands and sampling months. Anammox rates and Ra did not vary significantly among the sampling months. Denitrification rates were positively correlated with water content, total organic carbon (TOC), total nitrogen, dissolved organic nitrogen, NH4+, NOx-, Fe2+, and Fe2+/Fe3+, but negatively related to pH. Anammox rates showed negative relationships with water content and TOC. Water content, temperature, and pH were crucial for organic carbon and Fe2+ availability with important implications on denitrification and anammox. Therefore, denitrification rates vary significantly, whereas anammox rates do not vary significantly across freshwater-oligohaline wetlands in the Min River Estuary.

Preparation of W/O Hypaphorine-Chitosan Nanoparticles and Its Application on Promoting Chronic Wound Healing via Alleviating Inflammation Block.

Chronic wound repair is a common complication in patients with diabetes mellitus, which causes a heavy burden on social medical resources and the economy. Hypaphorine (HYP) has good anti-inflammatory effect, and chitosan (CS) is used in the treatment of wounds because of its good antibacterial effect. The purpose of this research was to investigate the role and mechanism of HYP-nano-microspheres in the treatment of wounds for diabetic rats. The morphology of HYP-NPS was observed by transmission electron microscopy (TEM). RAW 264.7 macrophages were used to assess the bio-compatibility of HYP-NPS. A full-thickness dermal wound in a diabetic rat model was performed to evaluate the wound healing function of HYP-NPS. The results revealed that HYP-NPS nanoparticles were spherical with an average diameter of approximately 50 nm. The cell experiments hinted that HYP-NPS had the potential as a trauma material. The wound test in diabetic rats indicated that HYP-NPS fostered the healing of chronic wounds. The mechanism was through down-regulating the expression of pro-inflammatory cytokines IL-1ß and TNF-α in the skin of the wound, and accelerating the transition of chronic wound from inflammation to tissue regeneration. These results indicate that HYP-NPS has a good application prospect in the treatment of chronic wounds.

Vaccarin enhances intestinal barrier function in type 2 diabetic mice.

AIMS: Hyperglycemia and insulin resistance drive intestinal barrier dysfunction in type 2 diabetes (T2DM). Vaccarin, the main active component in the semen of traditional Chinese medicine Vaccaria has a definite effect on T2DM mice. The purpose of this study was to investigate whether vaccarin can enhance the intestinal barrier function in T2DM. MAIN METHODS: The T2DM mice model was established by streptozocin and high-fat diet. Vaccarin at a dose of 1 mg/kg/day was administered. We evaluated the effects of vaccarin on gut microbiota and intestinal barrier function by 16S rRNA sequencing, Western blot, quantitative fluorescent PCR (qPCR), and morphological observation. Moreover, we constructed a single layer of the human intestinal epithelium model to determine the effect of vaccarin in vitro. RESULTS: The experimental results showed that vaccarin alleviated inflammatory mediators in serum and intestinal tissue of mice (P < 0.05), which may depend on the improvement of tight junctions and gut microbiota (P < 0.05). Activation of extracellular regulated protein kinases (Erk1/2) stimulated myosin light chain kinase (MLCK). By inhibiting ERK expression (P < 0.05), vaccarin had similar effects to ERK inhibitors. In addition, the regulation of tight junction barriers also involved the abovementioned pathways in vivo. CONCLUSION: Vaccarin could protect the intestinal barrier by inhibiting the ERK/MLCK signaling pathway and modulate the composition of the microbiota. These results suggested that vaccarin may be an effective candidate for improving intestinal barrier changes in T2DM.

Preparation, characterization and wound healing effect of vaccarin-chitosan nanoparticles.

Wound healing is a complex, dynamic and difficult process. Much effort and attempt has been made to accelerate this process. The purpose of this study is to prepare nanoparticles loaded with vaccarin (VAC-NPS)hydrogel and evaluate its effect on promoting wound healing. In the present study, the physicochemical properties of VAC-NPS were characterized. Transmission electron microscopy (TEM) was used to observe the morphology of VAC-NPS. Human umbilical vein endothelial cells (HUVEC) was employed to assessment the biocompatibility of VAC-NPS in vitro. The wound healing function of VAC-NPS hydrogels was evaluated in the full-thickness dermal wound in a rat model. The results indicated that VAC-NPS was spherical like particles with uniform particle size distribution and no obvious aggregation with a diameter of (216.6 ± 10.1)nm. The loading capacity and encapsulation efficiency of VAC in the nanoparticles were (14.3 ± 1.2) % and (51.7 ± 1.7) % respectively. MTT assay demonstrated that the VAC-NPS had no cytotoxicity and could promote HUVEC proliferation and migration. In vivo results showed that VAC-NPS promotes wound healing, and the mechanism may be through up-regulating IL-1ß and PDGF-BB, promoting angiogenesis. VAC-NPS might have a potential application value for the treatment of the wound healing and a promising performance in bio-medically relevant systems.

Adaptation to Fasting in Crucian Carp (Carassius auratus): Gut Microbiota and Its Correlative Relationship with Immune Function.

Fasting influences the overall physiology of fish, and the knowledge how the gut microbiota, growth performances, and immune function in response to intermittent and long-term fasting is still insufficient. Here, we characterized the effects of fasting on the host-gut microbiota in crucian carp, which would enhance our insight into physiological adaptation to fasting. To achieve this, we investigated the gut microbial communities of crucian carp with different fasting stress, and corresponding immune and growth parameters. The gut microbial communities were structured into four clusters according to different fasting stress, namely one control group (feed regularly), two intermittent fasting groups (fasting period and re-feeding period, respectively), and one long-term fasting group. Intermittent fasting significantly improved the activity of superoxide dismutase (SOD) and lysozyme (LZM) (ANOVA, p < 0.05) and significantly increased alpha diversity and ecosystem stability of gut microbiota (ANOVA, p < 0.05). Gut length (GL) and condition factor (CF) showed no significant difference between the control group (CG) and intermittent fasting group under re-feeding period (RIF) (ANOVA, p = 0.11), but relative gut length (RGL) in group RIF was higher than that in the CG (ANOVA, p = 0.00). The bacterial genera Bacteroides, Akkermansia, and Erysipelotrichaceae were enriched in fishes under intermittent fasting. Two Bacteroides OTUs (OTU50 and OTU1292) correlated positively with immune (SOD, complement, and LZM) and growth (GL and RGL) parameters. These results highlight the possible interplay between growth performances, immune function, and gut microbiota in response to fasting.

Effects of novel brominated flame retardant TBBPA on human airway epithelial cell (A549) in vitro and proteome profiling.

The cellular toxicity response of human airway epithelial cells (A549) to tetrabromobisphenol (TBBPA) was assessed in vitro. Cell viability, levels of intracellular reactive oxygen species (ROS), lipid peroxidation (MDA), and caspase-3 activity were determined after A549 treated with varying concentrations of TBBPA. A comparative proteomic analysis was performed in cells treated with different concentrations of TBBPA (0, 10, and 40 µg/mL). Two-way anova analysis showed that cell viability was significantly decreased after treatment by TBBPA with a concentration of 16 µg/mL for 48 hr, however, the caspase-3 activities, ROS generation, and MDA content increased. Ultrastructural observation revealed that the cell was morphological damaged after exposure to 64 µg/mL TBBPA, with mitochondria seriously injured and the smooth endoplasmic reticulum dilated. There was a good correlation between ROS generation and mitochondrial dysfunction. Seventeen differentially expressed proteins involved in various biological processes were identified. These findings provide a basis for understanding the mechanisms of cell dysfunction and perturbation of antioxidant status induced by additive flame retardant on airway epithelial cells.