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The volatile organic compound acetoin enhances the colonization of Azorhizobium caulinodans ORS571 on Sesbania rostrata
No full textChemoreceptors play a crucial role in assisting bacterial sensing and response to environmental stimuli. Genome analysis of Azorhizobium caulinodans ORS571 revealed the presence of 43 putative chemoreceptors, but their biological functions remain largely unknown. In this study, we identified the chemoreceptor AmaP (methylaccepting protein of A. caulinodans), characterized by the presence of the CHASE3 domain and exhibited a notable response to acetoin. Thus, we investigated the effect of acetoin sensing on its symbiotic association with the host. Our findings uncovered a compelling role for acetoin as a key player in enhancing various facets of A. caulinodans ORS571's performance including biofilm formation, colonization, and nodulation abilities. Notably, acetoin bolstered A. caulinodans ORS571's efficacy in promoting the growth of S. rostrata, even under moderate salt stress conditions. This study not only broadens our understanding of the AmaP protein with its distinctive CHASE3 domain but also highlights the promising potential of acetoin in fortifying the symbiotic relationship between A. caulinodans and Sesbania rostrata
Biodiversity and distribution patterns of blooming jellyfish in the Bohai Sea revealed by eDNA metabarcoding
No full textBackgroundThe mass occurrence of scyphozoan jellyfish severely affects marine ecosystems and coastal economies, and the study of blooming jellyfish population dynamics has emerged in response. However, traditional ecological survey methods required for such research have difficulties in detecting cryptic life stages and surveying population dynamics owing to high spatiotemporal variations in their occurrence. The environmental DNA (eDNA) technique is an effective tool for overcoming these limitations.ResultsIn this study, we investigated the biodiversity and spatial distribution characteristics of blooming jellyfish in the Bohai Sea of China using an eDNA metabarcoding approach, which covered the surface, middle, and bottom seawater layers, and sediments. Six jellyfish taxa were identified, of which Aurelia coerulea, Nemopilema nomurai, and Cyanea nozakii were the most dominant. These three blooming jellyfish presented a marked vertical distribution pattern in the offshore regions. A. coerulea was mainly distributed in the surface layer, whereas C. nozakii and N. nomurai showed a upper-middle and middle-bottom aggregation, respectively. Horizontally, A. coerulea and C. nozakii were more abundant in the inshore regions, whereas N. nomurai was mainly distributed offshore. Spearman's correlation analysis revealed a strong correlation between the eDNA of the three dominant blooming jellyfish species and temperature, salinity, and nutrients.ConclusionsOur study confirms the applicability of the eDNA approach to both biodiverstiy evaluation of blooming jellyfish and investigating their spatial distribution, and it can be used as a supplementary tool to traditional survey methods
Tetraspanin CD53 regulates peripheral blood leucocytes vitality and pathogen infection in turbot<i> (Scophthalmus</i><i> maximus)</i>
No full textCluster of differentiation 53 (CD53) also known as OX44 or tetraspanin 25 (TSPAN25) is a glycoprotein belonging to the tetraspanin family. Members of the tetraspanin family are characterized by four transmembrane domains, including intracellular N- and C-termini, and small and large extracellular domains. Currently, the function of CD53 in teleost is not well understood. In this study, we identified a CD53 (named SmCD53) from turbot (Scophthalmus maximus) and examined its expression and biological activity. SmCD53 contained 231 amino acid residues and was predicted to be a tetraspanin with small and large extracellular domains. SmCD53 expression was observed in different tissues, particularly in immune-related organs. Experimental infection with bacterial or viral pathogen significantly up-regulated SmCD53 expression in a time-dependent manner. Immunofluorescence microscopy analysis showed that SmCD53 was localized on the surface of PBL and was recognized by antibody against its large extracellular domain. Ligation of SmCD53 onto PBLs with antibodies suppressed the respiratory burst activity, inflammatory reaction, and enhanced cell viability. SmCD53 knockdown significantly enhanced bacterial dissemination and proliferation in turbot. Overall, these results underscore the importance of CD53 in the maintenance of the function and homeostasis of the immune system
Moderate increase of precipitation stimulates CO<sub>2</sub> production by regulating soil organic carbon in a saltmarsh
No full textSaltmarsh is widely recognized as a blue carbon ecosystem with great carbon storage potential. Yet soil respiration with a major contributor of atmospheric CO2 can offset its carbon sink function. Up to date, mechanisms ruling CO2 emissions from saltmarsh soil remain unclear. In particular, the effect of precipitation on soil CO2 emissions is unclear in coastal wetlands, due the lack of outdoor data in real situations. We conducted a 7-year field manipulation experiment in a saltmarsh in the Yellow River Delta, China. Soil respiration in five treatments (-60%, -40%, +0%, +40%, and + 60% of precipitation) was measured in the field. Topsoils from the last 3 years (2019-2021) were analyzed for CO2 production potential by microcosm experiments. Furthermore, quality and quantity of soil organic carbon and microbial function were tested. Results show that only the moderate precipitation rise of +40% induced a 66.2% increase of CO2 production potential for the microcosm experiments, whereas other data showed a weak impact. Consistently, soil respiration was also found to be strongest at +40%. The CO2 production potential is positively correlated with soil organic carbon, including carbon quantity and quality. But microbial diversity did not show any positive response to precipitation sizes. r-/K-strategy seemed to be a plausible explanation for biological factors. Overall, our finding reveal that a moderate precipitation increase, not decrease or a robust increase, in a saltmarsh is likely to improve soil organic carbon quality and quantity, and bacterial oligotroph:copiotroph ratio, ultimately leading to an enhanced CO2 production
Surfactant-Free Method to Prevent Gold Nanoparticle Aggregation and Its Surface-Enhanced Raman Scattering Applications
No full textThe introduction of surfactants to stabilize colloidal citrate-reduced gold nanoparticles (prevent aggregation) is usually used in surface-enhanced Raman scattering (SERS) applications. However, the surfactants have many drawbacks for SERS applications, such as increasing the SERS background and blocking surface active sites. Here, we develop a surfactant-free method to stabilize colloidal cit-AuNPs based on alkali regulation, and this method can prevent gold nanoparticle aggregation under different harsh treatments, including ligand modification, centrifugation-based washing/enrichment, and salt addition. The SERS spectra, density functional theory simulation, and zeta potentials of cit-AuNPs indicate that the stability of enhanced cit-AuNPs under alkaline conditions is attributed to both the increased negative charge density (by similar to 6 times from pH 7 to 12) and the molecular configuration on the metal surface. Compared with surfactant-based methods, this method can well maintain the inherent optical and interface properties of nanoparticles, avoid the SERS background, and avoid blocking of the surface active site due to the presence of surfactants. This method will enable AuNPs to have a wide range of applications in areas such as highly sensitive SERS sensors
NIR-activatable nitric oxide generator based on nanoparticles loaded small-molecule photosensitizers for synergetic photodynamic/gas therapy
No full textBackgroundTherapeutic approaches that combine conventional photodynamic therapy (PDT) with gas therapy (GT) to sensitize PDT are an attractive strategy, but the molecular structure design of the complex lacks effective guiding strategies.ResultsHerein, we have developed a nanoplatforms Cy-NMNO@SiO2 based on mesoporous silica materials loaded NIR-activatable small-molecule fluorescent probe Cy-NMNO for the synergistic treatment of photodynamic therapy/gas therapy (PDT/GT) in antibacterial and skin cancer. The theoretical calculation results showed that the low dissociation of N-NO in Cy-NMNO enabled it to dissociate effectively under NIR light irradiation, which is conducive to produce Cy and NO. Cy showed better 1O2 generation performance than Cy-NMNO. The cytotoxicity of Cy-NMNO obtained via the synergistic effect of GT and PDT synergistically enhances the effect of photodynamic therapy, thus achieving more effective tumor treatment and sterilization than conventional PDT. Moreover, the nanoplatforms Cy-NMNO@SiO2 realized efficient drug loading and drug delivery.ConclusionsThis work not only offers a promising approach for PDT-GT synergistic drug delivery system, but also provides a valuable reference for the design of its drug molecules
Surface enhanced Raman scattering microtips for microenvironment pH determination of semi-solid preparations
No full textSemi-solid preparations such as ointments, creams, gels, and pastes are common topical dosage forms with complex compositions and microstructures. pH is a critical quality attribute for semi-solid preparations, affecting properties such as particle size distribution, drug dissociation state, and rheological behavior. Currently, traditional pH electrode methods only provide an "average" pH for large-volume matrices, with low spatial resolution and accuracy. Microenvironment pH detection is crucial for accurately assessing semi-solid preparations. Herein, we developed pH-sensitive surface enhanced Raman scattering (SERS) microtips to achieve localized pH detection in semi-solid preparations. SERS microtips were prepared from glass needles with a tip size of around 1 mu m and gold nanoparticles (Au NPs) grown in situ on glass surfaces for SERS enhancement. 4-Mercaptopyridine was selected as a pH sensitive Raman reporter and immobilized on the Au NPs, exhibiting characteristic Raman peak shifts within the pH range of 3-10. The SERS microtips were employed to conduct highly sensitive pH measurements in localized areas of 15 commercial ointments, 8 gels, and 1 laboratory-made ointment, providing higher spatial resolution and microenvironment differentiation compared to pH meters. The SERS microtips were used to monitor pH changes over time in ointment applied to localized wounds on live mice. This work introduces a new tool for pH detection in semi-solid preparations, offering a new method to enhance the prescription process and quality assessment of complex preparations like topical semi-solid preparations.
Microregion pH of semi-solid preparations such as ointments, creams, gels can be revealed by pH-sensitive surface enhanced Raman scattering microtips
Identifying the key factors influencing spatial and temporal variations of regional coastal fishing activities
No full textFishing is one of the most pervasive human activities for harvesting natural resources. Accurate understanding of the dynamic variations of regional fishing activities and their influence mechanisms is crucial for marine conservation and fisheries management. Previous studies have described the spatio-temporal distribution of fishing operations. However, there is still a need for a comprehensive interpretation of why and how these variations occur, especially in regional coastal waters. In this study, taking the Bohai Sea and its adjacent waters as an example, the correlation between regional fishing activities and multiple factors, including the marine environment, geographical position, socio-economic conditions, and marine management policies, was investigated from the perspective of human geography. Automatic Identification System (AIS) data for fishing vessels were used, combining remote sensing, geographic information system (GIS), and statistical models. The results indicated that the spatio-temporal variations of regional coastal fishing activities were driven by complex interactions among these factors. Overall, the average explanatory power of socio-economic and geographical position factors on fishing activities was higher than that of marine environmental factors. The importance of the marine environment and geographical position for fishing activities varied throughout different seasons. The sensitivity of fishing activities to geographical position was relatively high, with the explained deviance exceeding 62% of the total explained deviance. Intensive fishing was primarily observed within a particular range of the sea surface temperature frontal gradient (0.20-0.60 degrees C/km) or sea surface chlorophyll-a frontal gradient (1.06-1.25). The spatial distribution of fishing activities is effectively constrained by implemented marine management policies. This study sheds new light on the key factors influencing regional fishing activities in coastal waters and highlights the complexity of their interaction effects. These findings can provide a theoretical basis for the restoration of fishery resources and marine fishing management
Construction of a myoglobin scaffold-based biocatalyst for the biodegradation of sulfadiazine and sulfathiazole
No full textSulfonamide antibiotics, a family of broad-spectrum antibiotic drugs, are increasingly used in aquaculture and are frequently detected in aquatic environments. This poses a potential threat to organisms and may cause the evolution of antimicrobial resistance. Therefore, it is important to develop an environmentally friendly and efficient biocatalyst to degrade sulfonamides (SAs) such as sulfadiazine (SD) and sulfathiazole (ST). Here, we realized the direct and efficient degradation of SD and ST using a hydrogen peroxide-dependent artificial catalytic system based on myoglobin (Mb). The arrangements of amino acids at positions 29, 43, 64, and 68 were found to influence catalytic activity. An L29H/H64D/V68I myoglobin mutant showed the best catalytic efficiency (i.e., kcat/Km = 720.42 M-1 s-1) against SD. Next, mutant H64D/V68I showed the best degradation rate against SD (i.e., 91.45 +/- 0.16%). Moreover, L29H/H64D/V68I Mb was found to efficiently catalyze ST oxidatio
Nitrate transformation and source tracking of rivers draining into the Bohai Sea using a multi-tracer approach combined with an optimized Bayesian stable isotope mixing model
No full textExcessive levels of NO3 -can result in multiple eco-environmental issues due to potential toxicity, especially in coastal areas. Accurate source tracing is crucial for effective pollutant control and policy development. Bayesian models have been widely employed to trace NO3 -sources, while limited studies have utilized optimized Bayesian models for NO3 - tracing in the coastal rivers. The Bohai Rim is highly susceptible to ecological disturbances, particularly N pollution, and has emerged as a critical area. Therefore, identification the N fate and understanding their sources contribution is urgent for pollution mitigation efforts. In addition, understanding the influenced key driven factors to source dynamic in the past ten years is also implication to environmental management. In this study, water samples were collected from 36 major river estuaries that drain into the Bohai Sea of North China. The main transformation processes were analyzed and quantified the sources of NO3 -using a Bayesian stable isotope mixing model (MixSIAR) with isotopic approach (815N-NO3- and 818O-NO3-). The overall isotopic composition of 815N-NO3- and 818O-NO3- in estuary waters ranged from -0.8-19.3%o (9.3 +/- 4.6%o) and from -7.1-10.5%o (5.0 +/- 4.3%o), respectively. The main sources of nitrate in most river estuaries were manure & sewage, and chemical fertilizer, while weak denitrification and mixed processes were observed in Bohai Ri