Search Results (408)

The toxicity of copper (Cu) severely affects the growth and physiological metabolism of plants. 2-(3,4-Dichlorophenoxy) triethylamine (DCPTA) is a plant growth regulator known to enhance plant tolerance to various abiotic stresses; however, its specific role in mitigating Cu toxicity via cell wall modulation and nitrogen metabolism remains unclear. “Zhongnong 26” (Cucumis sativus L.) seedlings were subjected to a randomized block design with four treatments: control (CK), 0.25 mg/L DCPTA, 50 μM Cu, and 50 μM Cu + 0.25 mg/L DCPTA, with three biological replicates per treatment. The results indicated that DCPTA application significantly alleviated Cu-induced growth inhibition. Specifically, DCPTA improved root system architecture by markedly increasing total root length (68.8%), surface area (68.7%), and the number and length of secondary lateral roots (69.6%, 173.2%). Furthermore, DCPTA enhanced the biosynthesis of cell wall polysaccharides—including pectin (24.3%), hemicellulose 1 (22.4%), hemicellulose 2 (23.7%) and cellulose (33.1%) in roots. Fourier Transform Infrared (FTIR) spectroscopy analysis revealed that DCPTA modified functional groups (e.g., –OH, –COOH) within the cell wall, enhancing their metal-chelating capacity. Consequently, DCPTA promoted the immobilization of Cu in the root cell wall fractions (particularly pectin and HC2) and shifted Cu into less toxic, pectate- and protein-bound forms, thereby reducing its translocation to leaves. Additionally, DCPTA restored the activities of key nitrogen metabolism enzymes in leaves and roots. Compared with Cu treatment alone, nitrate reductase (NR) activity increased by 77.7% and 90.6%, while glutamine synthetase (GS) activity remained stable, and glutamate synthase (GOGAT) activity increased by 10.3% and 71.3% in leaves and roots, respectively. In conclusion, DCPTA enhances copper sequestration in roots by coordinating the regulation of root structure and cell wall strengthening (with an increase in pectin and hemicellulose content). This is crucial for protecting the nitrogen metabolism within the cells (including the enzymes that drive the nitrate–ammonium reduction pathway) to maintain metabolic balance under Cu stress. Full article

Although numerous studies have focused on the potential application of heterotrophic nitrification–aerobic denitrification (HNAD) bacteria in wastewater treatment, research exploring their potential in aquaculture biofloc systems remains limited. In this study, a promising HNAD strain, identified as Stutzerimonas stutzeri MJ20, was isolated from mature biofloc. This strain efficiently utilized low-cost carbon sources (e.g., glucose) and small-molecule carbon sources (e.g., sodium acetate and sodium succinate). Under conditions with glucose as the carbon source, a carbon-to-nitrogen (C/N) ratio of 15, pH 6–9, temperature 25–35 °C, salinity 0–35‰, and shaker speed of 0–150 rpm, it achieved removal rates of 95–100% for NH₄⁺-N, NO₂⁻-N, and NO₃⁻-N at initial concentrations of 100 mg/L each. Even at higher concentrations (up to 200 mg/L NH₄⁺-N and 500 mg/L for both NO₂⁻-N and NO₃⁻-N), removal rates exceeded 99%. Under mixed nitrogen sources, strain MJ20 demonstrated efficient nitrogen removal, preferentially utilizing NH₄⁺-N, with only minimal and transient accumulation of nitrite and nitrate. Genomic analysis revealed that MJ20 carries key denitrification genes, including napA, nirS, norB and nosZ, and possesses complete pathways for nitrate reduction to nitrogen gas and ammonia assimilation, although typical autotrophic nitrification genes were not detected. Combined genomic data and autotrophic culture experiments indicated that, in addition to utilizing various organic carbon sources, the strain also exhibited certain autotrophic growth capabilities. Furthermore, MJ20 showed strong flocculation ability (flocculation rate > 96% within 16 h), sensitivity to multiple common antibiotics, and no toxicity to zebrafish, demonstrating favorable biosafety. In simulated seawater aquaculture wastewater with a C/N ratio of 5, it achieved a total nitrogen removal rate exceeding 94% within 72 h. These results indicate that strain MJ20 possesses comprehensive advantages, including efficient nitrogen removal, broad carbon source adaptability, strong environmental resilience, minimal accumulation of intermediate nitrogen products, excellent flocculation ability, and high biosafety. These traits highlight its potential for application in biofloc systems and in treating aquaculture tail water with a low C/N ratio. This study provides theoretical insights and practical guidance for screening HNAD bacteria suitable for biofloc systems. Full article

We examined neocortical pathology and interneuron degeneration in neonatal hypoxia-ischemic encephalopathy (HIE). Piglets in two age groups (2–3 or 7–10 days old, n = 4–12/group) underwent global cerebral hypoxia–ischemia (HI) or sham treatment. Piglets (2–3 days old) had epidural electrodes for continuous electroencephalography (cEEG) and were treated with hypothermia (HT) or remained at normothermia (NT). Older piglets, all NT, had scalp EEG. Piglets at both ages had seizures and survived for 1–7 days. Cortical damage was assessed by hematoxylin & eosin staining and immunohistochemistry; calretinin (CR), parvalbumin (PV), and vasoactive intestinal peptide (VIP) interneurons (INs) were counted. Cell injury was assessed by DNA fragmentation and protein nitration. TAR DNA binding protein-43 (TDP43) and the DNA repair scaffold protein X-ray repair cross complementing-1 (XRCC1) were examined for degeneration mechanisms. Cortical layers 3 and 4 showed high vulnerability; damage emerged as isolated cells, focal and laminar, and distributed as panlaminar throughout different cortical regions that correlated with seizure burden. HT protected strongly against cortical damage. CR- and PV-INs were severely depleted in HI-NT piglets compared to sham. VIP INs appeared invulnerable. HT partially rescued the loss of INs. CR and PV formed nuclear and cytoplasmic inclusions that colocalized with TDP43 and XRCC1; co-immunoprecipitation identified interactions among these proteins, and tyrosine nitration of CR. CR and PV INs accumulated DNA single- and double-strand breaks and appeared as attritional apoptosis variants with proteinopathy. This cell death is identified as aggreosis. IN loss correlated with seizure presence. Postmortem human neonatal HIE cases had a similar loss of CR and PV INs and nuclear depletion of TDP43 in the neocortex. Thus, neonatal HIE causes the loss of neocortical inhibitory IN subtypes with vulnerabilities instructed by their intrinsic calcium-binding protein signature and by mechanisms consistent with toxic sequestration and the nuclear depletion of XRCC1 and TDP43 underlying DNA damage accumulation. Early inhibitory IN deletion could drive seizure evolution in HIE; TDP43 and XRCC1 could be therapeutic targets for neonatal HIE. Full article

Aluminum (Al) toxicity constrains plant performance in acidic volcanic soils, yet nitrogen (N) fertilization may influence Al availability and plant responses. This study evaluated the effects of N source and rate under contrasting soil liming conditions on vegetative growth, mineral nutrition, and physiological performance of non-bearing northern highbush blueberry (Vaccinium corymbosum L. cv. Blue Ribbon^®) plants. A split–split-plot experiment was conducted in southern Chile using urea or potassium nitrate applied at 0, 20, or 40 kg N ha⁻¹ to plants grown in unlimed soil or soil amended with calcium carbonate or magnesium oxide. Vegetative growth, tissue mineral composition, stomatal conductance, chlorophyll fluorescence, and leaf chlorophyll were monitored during the first season. Growth responded primarily to soil liming rather than N supply, indicating low N demand and substantial soil N mineralization under the experimental conditions. Foliar N increased from 1.36 to 1.70% with increasing N rates. Urea nutrition reduced foliar Al concentration by 12% compared with nitrate. Under unlimed conditions, representing maximal soil Al availability, urea fertilization was associated with 70% higher Al retention in roots relative to nitrate. Chlorophyll content was consistently higher under urea supply, while the maximum photochemical efficiency of photosystem II remained unaffected. These findings indicate that N form influences plant Al partitioning independently of growth responses. Although the underlying mechanisms were not directly assessed, the observed patterns suggest that urea fertilization may reduce Al translocation to shoots under conditions of high Al availability. Full article

Shoot tip cryopreservation is essential for the long-term conservation of plant genetic resources. It provides the only reliable method for establishing a long-term, readily available gene pool of clonally propagated crops and elite in vitro clones used in the pharmaceutical, food, and cosmetic industries. Still, its success is often limited by the inherent sensitivity of many species to the osmotic and chemical stresses imposed by concentrated cryoprotectant (vitrification) solutions and severe dehydration. The optimization of modern cryopreservation protocols primarily focuses on modifying shoot tip preculture, cryoprotectant treatments, or regrowth conditions, while frequently overlooking donor plant preconditioning or relegating it to a secondary role. However, the physiological state of in vitro plants from which apical or axillary shoot tips are extracted may hold the key to successful post-cryopreservation recovery, especially in cryo-sensitive taxa. This review revisits the critical role of donor plant vigor and induced stress tolerance in the cryopreservation of clonal crops by systematically evaluating preconditioning strategies, including cold acclimation, sucrose pretreatment, and the use of growth regulators and signaling molecules such as abscisic, jasmonic, and salicylic acids, involved in stress signaling and tolerance development. The beneficial physiological changes induced by donor plant pretreatment, such as reduced freezable water content and the accumulation of protective compounds, are discussed in the context of contemporary cryopreservation methods. The effects of culture conditions, including the roles of ammonium and nitrates, light quality, culture density and aeration, medium strength, culture age, and subculture duration, are also considered. We analyze how different treatments of in vitro donor plants improve shoot tip tolerance to osmotic and/or chemical toxicity imposed by specific cryopreservation methods to support a material-centered selection of a cryopreservation procedure. Future directions and potential approaches for integrating target donor plant preconditioning into modern cryopreservation protocols for shoot tips, particularly in stress-sensitive species, are discussed. Full article

Coal-fired power plants can adversely affect aquatic ecosystems through wastewater discharge, waste landfills, and the atmospheric deposition of toxic substances released during coal combustion. These processes degrade the water quality of nearby surface and underground water bodies. The study presents the impact of the coal-fired power plant Contour Global Maritza East 3 on the ecological status of the Sokolitsa River, reflected by changes in the composition and structure of the sensitive phytobenthos and macrozoobenthos communities and supporting environmental variables, including water temperature, pH, dissolved oxygen, conductivity, nutrients, sulfates, calcium, and calcium carbonate hardness. Methods for monitoring and assessing the ecological status of surface water bodies compliant with European and national legislation were applied to the studied biological quality elements and key physicochemical variables. Historical monitoring data from a ten-year period, 2013–2022, together with data collected during the study in 2023 and 2024 were analyzed and evaluated. The results indicated a significant increase in most physicochemical variables downstream of the CFPP compared with the upstream site, including water temperature, conductivity, calcium carbonate hardness, calcium, sulfates and nitrogen (N) nutrients (ammonium N, nitrite N, nitrate N, total N). The ecological status of the river deteriorated, as indicated by the negatively affected aquatic habitats and the changes in the taxonomic richness and abundance of the studied organism groups. Full article

The green synthesis of nanomaterials has emerged as a sustainable and environmentally friendly approach, gaining significant attention in recent years for its potential in a wide range of multifunctional applications. Among these materials, zinc oxide nanoparticles (ZnO NPs) stand out due to their remarkable versatility and effectiveness in fields such as industry (food, chemistry, and cosmetics), nanomedicine, cancer therapy, drug delivery, optoelectronics, sensors, and environmental remediation. This study focuses on bioinspired strategies for the facile synthesis of ZnO NPs, employing natural polysaccharide gums as mediators. Acting as both reducing and stabilizing agents, natural gums not only facilitate the eco-friendly production of ZnO NPs but also enhance their stability and functionality. Natural gum-mediated green synthesis typically yields stable, spherical ZnO particles, often in the 10–100 nm range. Typical reaction conditions are the use of zinc acetate dihydrate or zinc nitrate (0.01–0.5 M) as precursors, with low gum concentrations of 0.1–1.0% (w/v) in distilled water, alkaline conditions (pH from 8 to 12), often achieved by adding NaOH, which aids in the reduction and capping by the gum, at reaction temperature between 60 °C and 80 °C, under continuous stirring. The dried precipitate is often calcined at 400 °C to 600 °C to remove organic residues and enhance crystallinity. This approach underscores the potential of biopolymer-assisted synthesis in advancing green nanotechnology for sustainable and practical applications. Utilizing environmentally benign materials such as natural gums for the synthesis of ZnO NPs offers significant advantages, including enhanced eco-friendliness and biocompatibility, making them suitable for a wide range of applications without the involvement of toxic reagents. This review provides an in-depth analysis of the synthesis and characterization techniques employed in the eco-friendly production of ZnO NPs using different natural gums from biological sources and its environmental applications (e.g., pollutant removal and increased agriculture sustainability). Full article

Inorganic lead (Pb) poses a significant public health concern due to its toxicity and widespread industrial use. Dermal contact, an under-researched pathway of Pb exposure relative to inhalation and ingestion, is typically not factored into regulatory exposure limits because of the paucity of validated studies. This study investigated the influence of sweat on the bioaccessibility of inorganic lead for dermal absorption. Dissolution testing was conducted to determine the dissolution kinetics of inorganic Pb (lead nitrate) in synthetic sweat relative to deionized water (DIW). Particle sizes of samples ranged from 0.70 µm to 118 µm. Non-linear dissolution kinetics were observed in both DIW (control) and sweat. The iPb ion concentration in DIW after 3 h (test period) accounted for 100% of the initial mass of iPb, compared to 67% of the initial mass of iPb in sweat. Higher variability was observed in sweat (SD: 1.47 to 8.2) compared to DIW (SD: 0.80 to 3.88). Precipitation was observed in sweat but not in DIW. Wilcoxon rank-sum test indicated a statistically significant difference in dissolution between sweat and deionized water (Z = −4.50, p < 0.0001). Findings suggest that sweat composition limits the extent of dissolution of soluble inorganic Pb, thereby influencing its dermal bioaccessibility. Full article

Abiotic stresses including drought, salinity, heat, cold, and heavy metal toxicity severely constrain plant productivity worldwide. Nitrogen (N), beyond its fundamental nutritional role, has emerged as a central regulator of plant stress responses through its involvement in metabolic reprogramming, osmotic adjustment, antioxidant defense, and hormonal signaling. This review synthesizes current advances in understanding how nitrogen availability and form influence plant tolerance to major abiotic stresses. Particular emphasis is placed on nitrogen-mediated modulation of reactive oxygen species (ROS) scavenging systems, nitrogen–carbon metabolic coordination, phytohormonal crosstalk, osmoprotectant biosynthesis, and regulation of stress-responsive gene expression. Recent molecular insights highlight the role of nitrogen transporters, nitrate signaling pathways, and nitrogen-use efficiency in stress adaptation mechanisms. Furthermore, agronomic and biotechnological strategies aimed at optimizing nitrogen management to enhance stress resilience are discussed, including precision fertilization, integrated nutrient management, and genetic approaches targeting nitrogen-responsive regulatory networks. By integrating physiological, biochemical, and molecular perspectives, this review provides a comprehensive framework for understanding nitrogen-driven mitigation strategies under abiotic stress conditions and outlines future research directions for sustainable crop production in changing environments. Full article

The undegradable characteristics of heavy metals on environmental quality have become a serious human health concern. A study was conducted in a potato field to investigate the impact of soil amended with animal manure or biochar on the transport of toxic heavy metals and nitrates to runoff and seepage water. The soil in 18 field plots was separated, and each of 3 plots was mixed with biochar, chicken manure, vermicompost, sewage sludge, or cow manure, with 3 plots used as the control. Following a natural rainfall event, the impact of soil treatments on the runoff and infiltration water volume was monitored. Runoff water from the soil amended with biochar exhibited 10.6 L plot⁻¹, whereas cow manure exhibited 4.1 L plot⁻¹, indicating about 61% reduction in runoff water volume. The vermicompost-amended soil increased the seepage water volume from 1.6 L plot⁻¹ in the control treatment to 4.4 L plot⁻¹, indicating a 175% increase in percolating water, a desirable attribute to direct rainfall water towards the plant roots. The concentrations of Pb, Cd, Ni, Mn, Cr, Mg, Cu, and K in infiltration water were greater in runoff sediments, highlighting the need for runoff sediment remediation technology. Full article

Research on heterotrophic bioflocs is extensive, whereas investigations into autotrophic bioflocs remain limited. This study established an in situ autotrophic biofloc (ABF) system for intensive Pacific white shrimp (Penaeus vannamei) farming, aiming for zero water exchange and optimized water quality. A 120-day indoor experiment tested three stocking densities (300 (T1), 250 (T2), and 200 shrimp per m³ (T3)) with no water exchange. Water quality was monitored every two days, and bacterial communities were analyzed on days 10 and 70. The results indicated that ABF maturation was achieved by day 70 across all treatments, marked by three key indicators: (1) synchronous declines in nitrite and nitrate concentrations; (2) concurrent decreases in pH and total alkalinity approaching maturation; and (3) sustained high nitrogen removal efficiency (nitrite < 0.7 mg/L, ammonia < 0.6 mg/L). All density groups displayed similar patterns in both water quality dynamics and microbial community evolution. Bacterial analysis revealed that dominant genera such as Ruegeria, Bacillus, Muricauda, SM1A02, and Nitrospira played critical roles in toxic nitrogen removal, while pathogenic Klebsiella and Vibrio significantly decreased post-maturation. Heterotrophic nitrification and aerobic denitrification microorganisms (HNADMs) were identified as potentially responsible for nitrite accumulation. Nitrite accumulation was found in all groups. T2 and T3 achieved satisfactory breeding performance despite pre-maturation nitrate peaks exceeding 40 mg/L, whereas T1 suffered a low survival rate (27.47%) due to severe nitrite accumulation (>50 mg/L). A biofloc volume (BFV) of 4–8 mL/L effectively managed daily feed inputs of 75–110 g/m³. These findings lay a theoretical and technical foundation for the application of in situ ABF cultivation in intensive farming and enhance the sustainability of aquaculture. Full article

For the first time in the bay of Annaba (Southern Mediterranean), we studied the spatiotemporal distribution of potentially toxic benthic dinoflagellates: Ostreopsis cf. ovata, Prorocentrum lima, Coolia monotis, and Amphidinium carterae, hosted by the dominant macrophytes Posidonia oceanica, Padina pavonica, Codium fragile, and Halopteris scoparia. Sampling of these macrophytes was conducted weekly during spring and summer as well as bi-weekly in autumn and winter, from October 2022 to November 2023, at contrasting sites within Annaba Bay. The measured environmental parameters included temperature, pH, dissolved oxygen, salinity, ammonium, nitrate, nitrite, dissolved organic nitrogen, dissolved inorganic nitrogen, phosphate, dissolved organic phosphorus, silicate, and chlorophyll a. A proliferation of O. cf. ovata was recorded in July 2023, coinciding with a marked increase in temperature, with a maximum abundance exceeding 40 × 10³ cells g⁻¹ of fresh weight (FW) on H. scoparia and C. fragile. The maximum abundance of P. lima reached 8700 cells g⁻¹ FW on H. scoparia during July and August 2023. Coolia monotis exhibited a peak of 2800 cells g⁻¹ FW on H. scoparia. The abundance of A. carterae increased with temperature, reaching a maximum of 980 cells g⁻¹ FW on P. pavonica. The distribution of epiphytic dinoflagellates varied according to the macrophyte substrate. Overall, statistical analyses indicate that benthic dinoflagellate community structure is shaped by the combined effects of temperature, nutrient availability, and ecological niche differentiation, with temperature emerging as the dominant driver. This suggests that climate-driven increases in Mediterranean Sea surface temperatures are likely to extend the seasonal window of harmful benthic algal blooms, thereby enhancing ecological disturbances and potential risks to human health. This study provides the first assessment of BHAB dynamics along the Eastern Algerian coast, highlighting the role of ongoing regional warming in shaping future bloom patterns. Full article

Nitrate and Escherichia coli (E. coli) are two common pollutants present in dairy cattle drinking water troughs. At elevated levels, both pollutants can be of immediate health concern, but longer-term exposure to these pollutants at higher levels can also increase the risks of decreased fertility, diseases, and decreased milk production. This research focuses on evaluating several farms in central California and aims to survey levels of both nitrate and E. coli levels across the period of a year, while also determining the sources of each contaminant for assessing drinking water quality conditions and to help inform any future treatment or prevention considerations, which can potentially improve water quality. From the troughs sampled, nitrate was elevated in a significant portion (47%), and while not at highly toxic levels, the nitrate levels may be harmful over long-term exposure, especially if their feed has high nitrate content as well. The source of each contaminant is different; however, research showed nitrate already existing in groundwater supplies. In terms of E. coli, in general, groundwater had much lower levels of E. coli than water in the troughs, suggesting that the cattle themselves and trough surroundings are major contributors of E. coli in trough water. Full article

Fine particulate matter (PM_2.5) formation mechanisms in fragile highland ecosystems remain inadequately constrained, particularly regarding thermodynamic non-linearities (aerosol pH, liquid water content) and their interaction with geochemical modulation. Here, we present comprehensive year-long online measurements from Xining, Qinghai-Tibet Plateau, integrating hourly measurements of water-soluble ions, inorganic elements, and gaseous precursors with ISORROPIA-II thermodynamic modeling and ensemble machine learning. Median pH was 4.38 but exhibited two distinct pH regimes (14.8% pH < 3.0, 11.5% pH > 7.2), with acute acidification enhancing toxic metal solubility (Fe, Pb by 3-5×), and it posed distinct ecological risks. Our analysis reveals a distinct “highland mechanism triad” governing PM_2.5 dynamics: (1) winter meteorological confinement amplifying dust-catalyzed sulfate formation (SOR = 0.68); (2) spring alkaline dust buffering (pH > 7.2) that titrates NH₃ and suppresses nitrate formation (NOR < 0.10); and (3) summer photochemical oxidation constrained by chronic NH₃ limitation within an oxidant-excess regime. Random Forest achieved optimal prediction for the chemically active inorganic fraction (RMSE = 6.63 μg/m³, R² = 0.91) by learning regime-specific non-linearities, with local sensitivity analysis identifying Ca²⁺, SO₄²⁻, and Al as chemically sensitive drivers (S > 0.35) while revealing NH₃’s seasonally variable influence (rank 15 in winter, significant in summer; S > 0.28), subsequently complemented by global SHAP analysis, which further revealed NO₃⁻ as the most robust predictor (ranking 1st–2nd) and captured NH₃’s non-linear threshold effects (). Positive Matrix Factorization apportioned secondary aerosols (30.11%) within a unique alkaline–dust matrix. These findings demonstrate that highland PM_2.5 inorganic chemistry operates through fundamentally different pathways than lowland photochemical haze, with acid-induced toxic metal activation providing a new target for ecological protection in this fragile ecosystem. Seasonally adaptive mitigation is required: concurrent SO₂-NH₃ control in winter, dust suppression infrastructure in spring, and agricultural NH₃ capture in summer. This integrated framework provides a transferable methodology for air-quality management in alkaline dust-dominated, NH₃-limited highland ecosystems (>2000 m). Full article

Treatment of wastewater effluent is essential to reduce environmental impact and keep surface water clean, meeting sustainable criteria. While plant-based coagulants are known for their eco-friendly profiles, their dual application for high-efficiency nutrient removal and subsequent sludge valorization in fish farm systems remain under-explored. Therefore, this study was conducted to determine the optimum conditions for using natural coagulants to recover nutrients from fish farm effluent. Two types of natural coagulants, Alhagi graecorum leaves and apricot seeds, were evaluated for the treatment and recovery of nutrients from fish farm effluent due to their high removal efficiency, non-toxicity, and cost-effectiveness. In this study, optimization was performed using Response Surface Methodology (RSM) with a Central Composite Design (CCD) to investigate the effects of three factors: coagulant concentration (1000–7000 mg/L), wastewater pH (5–9), and settling time (15–35 min). The primary responses measured were the removal efficiencies of phosphate (PO₄) and nitrate (NO₃). According to the CCD results, maximum removal efficiencies reached 92.63% and 73.49% for PO₄ and NO₃, respectively. The optimal conditions were identified as pH 5, 1000 mg/L coagulant concentration, and a 35 min settling time for A. graecorum, and pH 9, 1000 mg/L concentration, and a 15 min settling time for apricot seed. These findings establish the optimal conditions for using these natural substances as effective agents for sustainable wastewater treatment and nutrient recovery. Full article