The volatile organic compound acetoin enhances the colonization of Azorhizobium caulinodans ORS571 on Sesbania rostrata

Chemoreceptors 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

An inversion model of microplastics abundance based on satellite remote sensing: a case study in the Bohai Sea

Nowadays, microplastics (MPs) as emerging contaminants have posed great risks to marine ecosystems and human health. However, non-continuous field sampling data makes it difficult to meet the needs of scientific research and pollution control of marine MPs. Consequently, the development of rapid monitoring techniques for marine MPs to achieve efficient acquisition of data is increasingly essential. Remote sensing technology provides a convenient and effective tool for monitoring and mapping marine MPs pollution. Therefore, we established an inversion model based on multiple regression by combining the remote sensing data and the measured data to predict the MPs pollution status in the Bohai Sea. The feature variables of a model are crucial to the prediction, and we proposed three methods of variable selection, namely successive projections algorithm (SPA), band combination method, and remote sensing index method. By comparing accuracy evaluation metrics, an approach based on SPA was selected to analyze the abundance and spatio-temporal distribution of MPs in the Bohai Sea in 2022. The determination coefficient of the SPA model is 0.75, and the root mean square error is 0.38 items/m3. The error of the model is within an acceptable range. It was found that the MPs abundance on the sea surface of the Bohai Sea varied significantly in different seasons and regions. This study indicates that satellite remote sensing technology has great potential in monitoring marine MPs

Habitat suitability assessment for Saunders's Gull (Saundersilarus saundersi) in the Yellow River Delta, China

The Yellow River Delta (YRD) is a key breeding place for Saunders's Gull (Saundersilarus saundersi), one of the vulnerable birds in the world. Thus, a thorough understanding of the key environmental factors influencing its suitable habitat holds great value for its conservation. Previous researches focused on Saunders's Gull's population changes and habitat features of breeding places in the nature reserve. However, its habitat suitability in the whole YRD has not been studied systematically, hindering the formulation of macro-protection policies to a certain extent. On the basis of occurrence records and environmental variables, we constructed an optimized MaxEnt model using the 'kuenm' R package to investigate the potential distribution of suitable habitat for the Saunders's Gull in the YRD. Results showed that the ideal hyperparameters for the MaxEnt model were a feature combination of linear and quadratic terms, and the regularization multiplier of 0.6 after optimization, indicated a high level of prediction accuracy. The environmental factors that had a significant effect on the Saunders's Gull's distribution were land use and land cover, percentage of beach saline-alkali land (PLAND_55) and distance to coastline (D_coastline). The highly suitable habitat had an area of 258.56 km2, of which 66.63% was located within the YRD National Nature Reserve. The management of constructed wetlands should be combined with the protection of natural wetlands to avoid the disadvantage of 'isolated island-type' protection. The study provides insights into the quantitative relationship between waterfowl and their habitat, providing support for the sustainable development of the YRD, with certain practical significance

Aging in soil increases the disturbance of microplastics to the gut microbiota of soil fauna

Microplastics (MPs) in the soil environment inevitably experience aging processes. However, how aging in soil affects MP toxicity to soil fauna remains poorly understood. In this study, two types of widely distributed MPs (polypropylene and tire wear particles) were aged in different soils, and their surface properties, morphology, leaching features of additives, biofilm colonization and toxicity to the typical soil fauna Enchytraeus crypticus were investigated. Results showed that aging in soil slightly changed the surface properties and morphology for both types of MPs, but significantly affected the release of additives, especially for those MPs aged in soil amended with manure. Moreover, a distinct and less diverse microbial community than the surrounding soils was formed on the surface of MPs, and MP type was a determinant of the biofilm microbial community. Exposure experiments indicated that aged MPs, especially those aged in soil with manure significantly affected the reproduction of soil worms with a more obvious disturbance to their gut microbiota, and biofilm features and changes in the leaching properties of MPs during aging were the main factors for these shifts. This study is the first attempt to reveal the role of aging in soil in MP toxicity to soil fauna

The volatile organic compound acetoin enhances the colonization of Azorhizobium caulinodans ORS571 on Sesbania rostrata

Chemoreceptors 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

Recent advances and challenges in monitoring chromium ions using fluorescent probes

Chromium is among the most strategic and critical transition metal elements and has extensive applications in both industrial and biological contexts. The most stable oxidation states of chromium are trivalent chromium (Cr (III)) and hexavalent chromium (Cr(VI)). Cr(III) is recognized as an effective trace nutrient, whereas Cr(VI) in its highest oxidation state poses a toxic threat to human health due to its potent oxidizing capacities. To mitigate the risk of poisoning, efficient detection methods have been developed to meet testing requirements. Comparing with traditional methods, colorimetric and fluorescent techniques have emerged as simple, time-efficient, highly selective and sensitive, cost-effective and particularly well-suited for biological applications. Furthermore, these methods excel in distinguishing between trivalent and hexavalent chromium, even in low-level concentrations and complex matrices. Since the scarcity of fluorescent probes for chromium, most existing reviews merely touch upon this topic without providing comprehensive coverage. Therefore, this review aims to consolidate information on small molecular fluorescent probes and fluorescent materials serve as fluorescent probes for monitoring Cr2+, Cr3+, Cr2O72- and CrO42- in environmental settings and living cells. We anticipate that this review will promote the development of novel fluorescent probes for chromium detection, facilitating their applications in chemical, biological and medical domains

Construction of a myoglobin scaffold-based biocatalyst for the biodegradation of sulfadiazine and sulfathiazole

Sulfonamide 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

Anti-stokes fluorescence of phycobilisome and its complex with the orange carotenoid protein

Phycobilisomes (PBSs) are giant water-soluble light-harvesting complexes of cyanobacteria and red algae, consisting of hundreds of phycobiliproteins precisely organized to deliver the energy of absorbed light to chlorophyll chromophores of the photosynthetic electron-transport chain. Quenching the excess of excitation energy is necessary for the photoprotection of photosynthetic apparatus. In cyanobacteria, quenching of PBS excitation is provided by the Orange Carotenoid Protein (OCP), which is activated under high light conditions. In this work, we describe parameters of anti-Stokes fluorescence of cyanobacterial PBSs in quenched and unquenched states. We compare the fluorescence readout from entire phycobilisomes and their fragments. The obtained results revealed the heterogeneity of conformations of chromophores in isolated phycobiliproteins, while such heterogeneity was not observed in the entire PBS. Under excitation by low-energy quanta, we did not detect a significant uphill energy transfer from the core to the peripheral rods of PBS, while the one from the terminal emitters to the bulk allophycocyanin chromophores is highly probable. We show that this direction of energy migration does not eliminate fluorescence quenching in the complex with OCP. Thus, long-wave excitation provides new insights into the pathways of energy conversion in the phycobilisome

Habitat suitability assessment for Saunders's Gull (Saundersilarus saundersi) in the Yellow River Delta, China

The Yellow River Delta (YRD) is a key breeding place for Saunders's Gull (Saundersilarus saundersi), one of the vulnerable birds in the world. Thus, a thorough understanding of the key environmental factors influencing its suitable habitat holds great value for its conservation. Previous researches focused on Saunders's Gull's population changes and habitat features of breeding places in the nature reserve. However, its habitat suitability in the whole YRD has not been studied systematically, hindering the formulation of macro-protection policies to a certain extent. On the basis of occurrence records and environmental variables, we constructed an optimized MaxEnt model using the 'kuenm' R package to investigate the potential distribution of suitable habitat for the Saunders's Gull in the YRD. Results showed that the ideal hyperparameters for the MaxEnt model were a feature combination of linear and quadratic terms, and the regularization multiplier of 0.6 after optimization, indicated a high level of prediction accuracy. The environmental factors that had a significant effect on the Saunders's Gull's distribution were land use and land cover, percentage of beach saline-alkali land (PLAND_55) and distance to coastline (D_coastline). The highly suitable habitat had an area of 258.56 km2, of which 66.63% was located within the YRD National Nature Reserve. The management of constructed wetlands should be combined with the protection of natural wetlands to avoid the disadvantage of 'isolated island-type' protection. The study provides insights into the quantitative relationship between waterfowl and their habitat, providing support for the sustainable development of the YRD, with certain practical significance

An apparatus and method for improving saline-alkali soil

本发明公开了一种盐碱地改良设备及方法，涉及农业机械技术领域，该设备包括车体和设置在其下端的多个支腿，每个支腿下端都设有一个行走轮，所述行走轮连接用于带动其转动的行走电机，所述车体上还设有用于将土壤破碎并提起的破碎部件，通过破碎部件将土块破碎，所述车体尾部设有一个安装缺口，该安装缺口位置设有用于对土块进行输送的传输带，传输带的输入端连接输送电机，本发明针对现有需要进行设计，可以实现对不同深度土壤的挖掘和粉碎，并且可以将挖掘的土块进行粉碎，将粉碎后的土块进行平摊处理，平摊后的土块再均匀配上药剂，使得药剂与土块充分混合，保证了修复效果