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N 2 O emission in temperate seagrass meadows: Fluxes, pathway and molecular mechanism
No full textSeagrass meadows act as filters for nitrogen in coastal areas, but whether they are a source or sink for N 2 O has been still controversy. Additionally, the production pathways of N 2 O as well as the microbial driving mechanism in seagrass meadows are seldom reported. In this study, the air-sea fluxes, sediment release potential, and production pathway of N 2 O in a temperate Zostera marina and Z. japonica mixed meadow were investigated by using gas chromatography and 15 N isotopic tracing methods. The qPCR and metagenome sequencing were used to compare the difference in functional gene abundance and expression between seagrass vegetated and nongrass sediments. The results showed that the N 2 O air-sea fluxes in the meadow ranged from -1.97 to -1.77 nmol m - 2 h - 1 , which was slightly lower in the seagrass region than in the adjacent bare region. Seagrass sediment N 2 O release potential dramatically increased after warming and nitrogen enrichment treatments. Heterotrophic nitrification was firstly investigated in seagrass meadows, and the process (26.80% -62.41%) and denitrification (37.55% -72.83%) contributed significantly to N 2 O production in the meadow, affected deeply by sediment organic content, while the contribution of autotrophic nitrification can be neglected. Compared with the bare sediments, the ammonia monooxygenase genes amoA , amoB and amoC , and nitrite oxidoreductase genes nxrA and nxrB , as well as nitrite reductase gene nirS and nitric oxide reductase gene norB were down-regulated, while the nitrous oxide reductase gene nosZ was up-regulated in the seagrass sediments, explaining less N 2 O emission in seagrass regions from the perspective of molecular. The nosZII -bearing bacteria like Bacteroidia , Polyangia , Anaerolineae , and Verrucomicrobiae could play important roles in N 2 O reduction in the seagrass meadow. The result is of great significance for highlighting the ability of seagrass meadows to mitigate climate changes
Genome-Wide Identification and Comparative Analysis of Elongation of Very Long-Chain Fatty Acid (Elovl) Genes in Echinoderms
No full textElongation of very long-chain fatty acid (Elovl) proteins is the critical rate-limiting enzyme that catalyzes the biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFAs). Echinoderms are extremely important research objects in various fields, such as regeneration studies and developmental biology. However, to date, the genome-wide characterization and analysis of Elovl genes in echinoderms have not been investigated. In this study, the identification and analysis of Elovl genes in 10 representative echinoderms were performed using bioinformatics methods. A total of 117 Elovl genes have been found in the studied echinoderms. The phylogenetic tree showed that all Elovl genes from echinoderms can be subdivided into 6 classes, Elovl3-like class, Elovl4-like class, Elovl5-like class, Elovl6-like class, Elovl7-like class, and Elovl8-like class. Furthermore, the selection pressure analysis suggested that Elovl genes in echinoderms were mainly constrained by strong purifying selection events. In general, this study provides a molecular basis for echinoderm Elovl genes and may serve as a reference for in-depth phylogenomics
Effects of feeding Haematococcus pluvialis powder on astaxanthin accumulation, biochemical compositions, antioxidant activity, and gut microbial community in juvenile crucian carp (Carassius auratus L.)
No full textThe effect of Heamatoccus pluvialis on astaxanthin accumulation, nutrition, antioxidant activity, and gut health in juvenile crucian carp was investigated based on two ratios of alga powder in the feed (1:1 and 2:1). After 93 days of feeding, various organs and tissues of crucian carp, e.g., serum, scale, skin, muscle, kidney, and gut liver, were isolated and tested for astaxanthin content, fatty acids, amino acids, intestinal microbiota, and physiological and biochemical indicators. The results showed that among the various types of tissues, the scales and guts were revealed with the highest contents of astaxanthin (higher than 45.00 mu g/g), and 2.35 mu g/g in muscles in the fish. Although the compositions of astaxanthin in the fish tissues were mainly dependent on the contents of astaxanthin in the feed, the different tissues in the fish were selective in their uptake of astaxanthin isomers. The astaxanthin isomerization occurred in the fish, as suggested by the presence of two astaxanthin isomers (i.e., 13-Z astaxanthin and 9-Z astaxanthin) which were not available in the feed. The nutritional value of crucian carp muscles was increased by the elevated contents of essential amino acids and polyunsaturated fatty acids. Compared to the control group, the fish fed with H. pluvialis was revealed with significant changes in biochemical parameters and gut microbial compositions. Both the levels of antioxidant activity, as indicated by the blood total antioxidant capacity and the contents of catalase, malondialdehyde, glutathione peroxidase, and superoxide dismutase, and the antimicrobial activity, as indicated by the content of lysozyme, were significantly increased. In the gut, the beneficial bacteria (e.g., Lactobacillus and Lactococcus) became the dominant species, while the abundance of pathogenic bacteria (e.g., Xanthobacter, Legionella, and Gordonella) was significantly decreased. This study provided strong experimental evidence to support the application of H. pluvialis in the feed for crucian carp as an effective way to improve the nutritional value and immune activity of crucian carp, greatly promoting the healthy farming and food safety of crucian carp
Low salinity influences the dose-dependent transcriptomic responses of oysters to cadmium
No full textSpecies in estuaries tend to undergo both cadmium (Cd) and low salinity stress. However, how low salinity affects the Cd toxicity has not been fully understood. Investigating the impacts of low salinity on the doseresponse relationships between Cd and biological endpoints has potential to enhance our understanding of the combined effects of low salinity and Cd. In this work, changes in the transcriptomes of Pacific oysters were analyzed following exposure to Cd (5, 20, 80 mu g/L Cd2+) under normal (31.4 psu) and low (15.7 psu) salinity conditions, and then the dose-response relationship between Cd and transcriptome was characterized in a highthroughput manner. The benchmark dose (BMD) of gene expression, as a point of departure (POD), was also calculated based on the fitted dose-response model. We found that low salinity treatment significantly influenced the dose-response relationships between Cd and transcripts in oysters indicated by altered dose-response curves. In details, a total of 219 DEGs were commonly fitted to best models under both normal and low salinity conditions. Nearly three quarters of dose-response curves varied with salinity condition. Some monotonic doseresponse curves in normal salinity condition even were replaced by nonmonotonic curves in low salinity condition. Low salinity treatment decreased the PODs of differentially expressed genes induced by Cd, suggestin
The role of different wind input, whitecap dissipation and quadruplet wave-wave interaction terms in wave evolution in Lake Michigan
No full textIn present study, the sensitivity of WAVEWATCH-III model to different wind sources, formulations for wind input, whitecap dissipation and quadruplet wave-wave interaction was investigated during both fair weather and extreme condition of Hurricane Sandy in Lake Michigan. Wind data sets with finer spatial resolution (GLERL and GEM) led to better agreement with in-situ data, while ERA5 with coarser spatial resolution underestimated wind speed both in deep and shallow waters. Preparatory evaluation of model skill in reproducing wave bulk parameters indicated that the highest error was obtained when ST4 package and ERA5 wind data were employed in model. The calibration procedure was conducted by employing a combined error index. Simulated wave bulk parameters with optimum tuning values for GLERL and GEM wind data were in well agreement with in-situ data; however, GEM outperformed GLERL during extreme values of H s and T m in deep water buoys. Moreover, GLERL wind data slightly improved model skill in H s and T p estimation in shallow water buoys. Although more advanced methods were considered for quadruplet wave-wave interaction, DIA could be sufficiently reliable method for hindcasting wave bulk parameters. The DIA method systematically overestimated wave energy at low frequencies which was alleviated when GMD or GQM method was employed. Obtained directional wave spectra by using ST1 and ST6 packages combined with DIA were directionally broad as well as less energetic in peak frequency; however, GMD, GQM and WRT methods were led to more concentrated high energy content. In general, the quality and quantity of modeled wave spectra were in a reasonable agreement with observed one after model calibration
Low molecular weight chitosan based GSH-responsive self-assembled cationic micelle with enhanced anti-tumor effect by combining oxidative damage and chemotherapy
No full textA novel cationic lipoic acid grafted low molecular weight chitosan (LCNE-LA) conjugate was constructed and further self-assembled into GSH-responsive cationic nanocarrier to achieve better antitumor effect by combining encapsulated chemotherapy and oxidative damage induced by ROS. The resultant LCNE-LA cationic micelle exhibited favorable physicochemical properties (low CMC, small size, positively zeta potential and good stability), excellent biosafety and desired redox sensitivity. Next, doxorubicin (Dox) was embedded into hydrophobic core to form stable Dox/LCNE-LA micelle that had superior loading capacity. The GSH-induced release behavior, cellular uptake ability, ROS generation and GSH consumption capacity and in vitro antitumor activity of Dox/LCNE-LA micelle were systematically evaluated. Consequently, Dox/LCNE-LA cationic micelle with positively charged could efficiently enter into cancer cell and redox-sensitive release Dox via disulfide-thiol exchange reaction, which usually expend abundant GSH and disrupt redox homeostasis. Studies further confirmed that Dox/LCNE-LA micelle could increase ROS and reduced GSH content which might cause oxidative damage to tumor cell. Antitumor activity indicated that Dox/LCNE-LA micelle achieved an excellent cancerkilling effect, which might be attributed to combination treatment of Dox and ROS induce oxidative damage. Overall, this research was expected to provide a platform for antitumor treatment by triggering Dox release and promoting ROS generation
Effect of organic matter on the environmental behavior of sulfur and heavy metals in mariculture sediments during the aging process
No full textOrganic matter (OM) significantly impacts the environmental behavior of sulfur and heavy metals. In this study, the effects of OM on the migration and transformation of sulfur and heavy metals in mariculture sediments were investigated. The results indicated that baiting had a strong impact on the accumulation of acid volatile sulfur (AVS) ( P 15 %). An increase in the reducible fraction promoted the conversion of AVS to CRS, which reduced the degree of sediment aging. Higher OM levels reduced the diversity and abundance of the bacterial communities. The sulfate respiration functional microbiota was particularly affected by OM
Chronopotentiometric sensors for antimicrobial peptide-based biosensing of <i>Staphylococcus aureus</i>
No full textCharged antimicrobial peptides can be used for direct potentiometric biosensing, but have never been explored. We report here a galvanostatically-controlled potentiometric sensor for antimicrobial peptide-based biosensing. Solid-state pulsed galvanostatic sensors that showed excellent stability under continuous galvanostatic polarization were prepared by utilizing reduced graphene oxide/poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate) (rGO/PEDOT: PSS) as a solid contact. More importantly, the chronopotentiometric sensor can be made sensitive to antimicrobial peptides with intrinsic charge on demand via a current pulse. In this study, a positively charged antimicrobial peptide that can bind to Staphylococcus aureus with high affinity and good selectivity was designed as a model. Two arginine residues with positive charges were linked to the C-terminal of the peptide sequence to increase its potentiometric responses on the electrode. The bacteria binding-induced charge or charge density change of the antimicrobial peptide enables the direct chronopotentiometric detection of the target. Under the optimized conditions, the concentration of Staphylococcus aureus can be determined in the linear range 10-1.0 x 10(5) CFU mL(-1) with a detection limit of 10 CFU mL(-1). It is anticipated that such a chronopotentiometric sensing platform is readily adaptable to detect other bacteria by choosing the peptides
Aging increases the particulate- and leachate-induced toxicity of tire wear particles to microalgae
No full textThe toxic effects of tire wear particles (TWPs) on organisms have attracted widespread concerns over the past decade. However, the underlying toxicity mechanism of TWPs, especially aged TWPs to marine microalgae remains poorly understood. This study investigated the physiological and metabolic responses of Phaeodactylum tricornutum to different concentrations of TWPs (Experiment 1), virgin and differently aged TWPs (Experiment 2) as well as their leachates and leached particles (Experiment 3). Results demonstrated that TWPs promoted the growth of microalgae at low concentrations (0.6 and 3 mg L -1 ) and inhibited their growth at high concentrations (15 and 75 mg L -1 ). Moreover, aged TWPs induced more profound physiological effects on microalgae than virgin TWPs, including inhibiting microalgae growth, decreasing the content of Chla , promoting photosynthetic efficiency, and causing oxidative damage to algal cells. Untargeted metabolomics analysis confirmed that aged TWPs induced more pronounced metabolic changes than virgin TWPs. This study represented the first to demonstrate that both particulate- and leachate-induced toxicity of TWPs was increased after aging processes, which was confirmed by the changes in the surface morphology of TWPs and enhanced release of additives. Through the significant correlations between the additives and the microalgal metabolites, key additives responsible for the shift of microalgal metabolites were identified. These results broaden the understanding of the toxicity mechanism of aged TWPs to microalgae at the physiological and metabolic levels and appeal for considering the effects of long-term aging on TWP toxicity in risk assessment of TWPs
Sea cucumber physiological response to abiotic stress: Emergent contaminants and climate change
No full textThe ocean is facing a multitude of abiotic stresses due to factors such as climate change and pollution. Understanding how organisms in the ocean respond to these global changes is vital to better predicting consequences. Sea cucumbers are popular echinoderms with multiple ecological, nutritional, and pharmaceutical benefits. Here, we reviewed the effects of environmental change on an ecologically important echinoderm of the ocean, aiming to understand their response better, which could facilitate healthy culture programs under environmental changes and draw attention to knowledge gaps. After screening articles from the databases, 142 studies were included on the influence of emergent contaminants and climate variation on the early developmental stages and adults of sea cucumbers. We outlined the potential mechanism underlying the physiological response of sea cucumbers to emerging contaminants and climate change. It can be concluded that the physiological response of sea cucumbers to emergent contaminants differs from their response to climate change. Sea cucumbers could accumulate pollutants in their organs but are aestivated when exposed to extreme climate change. Research showed that the physiological response of sea cucumbers to pollutants indicates that these pollutants impair critical physiological processes, particularly during the more susceptible early phases of development compared to adults, and the accumulation of these pollutants in adults is often observed. For climate change, sea cucumbers showed gradual adaptation to the slight variation. However, sea cucumbers undergo aestivation under extreme conditions. Based on this review, critical suggestions for future research are presented, and we call for more efforts focusing on the co -occurrence of different stressors to extend the knowledge regarding the effects of environmental changes on these economically and ecologically important species