Search Results (170)

Ammonia is a common toxic pollutant in aquaculture environments that poses significant threats to the health, growth, and survival of aquatic organisms. This study investigates the physiological and molecular responses of triploid Crassostrea gigas to ammonia exposure, focusing on the activation and regulation of oxidative stress and immune-related pathways. By integrating histological observations, biochemical assays, and transcriptomic analysis, we systematically revealed the oxidative stress and immune regulatory mechanisms in the hepatopancreas of triploid C. gigas under ammonia exposure. Results showed significant tissue damage in the hepatopancreas, disrupted activities of key antioxidant enzymes including SOD, CAT, and GSH-Px, along with elevated MDA levels, indicating oxidative damage to cellular membrane lipids. Transcriptomic data further indicated significant activation of the glutathione metabolism pathway, with antioxidant genes such as GPX5 and GPX7 displaying a dynamic pattern of initial upregulation followed by downregulation, suggesting their critical roles in modulating oxidative stress responses and maintaining cellular homeostasis. Immunologically, ammonia exposure significantly activated lysosomal and phagosomal pathways, as well as multiple signaling cascades including FOXO, mTOR, and PI3K-Akt. Several key immune regulatory genes exhibited dynamic expression changes, reflecting coordinated regulation of apoptosis, autophagy, and energy metabolism to maintain immune defense and cellular homeostasis. Notably, dynamic expression of the GADD45 gene family in the FOXO signaling pathway underscores the important role of triploid C. gigas in mounting stress responses and adaptive immune regulation under ammonia toxicity. This study provides in-depth molecular insights into the integrated response mechanisms of triploid oysters to ammonia exposure, offering a molecular foundation for understanding bivalve adaptation to ammonia and revealing novel perspectives on molluscan ammonia tolerance. Full article

Soil salinization severely restricts crop growth and presents a major challenge to global agriculture. In this study, a plant-growth-promoting rhizobacterium (PGPR) was isolated and identified as Proteus sp. through 16S rDNA analysis and was subsequently named Proteus sp. JHY1. Under salt stress, exogenous dopamine (DA) significantly enhanced the production of indole-3-acetic acid and ammonia by strain JHY1. Pot experiments revealed that both DA and JHY1 treatments effectively alleviated the adverse effects of 225 mM NaCl on rice, promoting biomass, plant height, and root length. More importantly, the combined application of DA-JHY1 showed a significant synergistic effect in mitigating salt stress. The treatment increased the chlorophyll content, net photosynthetic rate, osmotic regulators (proline, soluble sugars, and protein), and reduced lipid peroxidation. The treatment also increased soil nutrients (ammoniacal nitrogen and available phosphorus), enhanced soil enzyme activities (sucrase and alkaline phosphatase), stabilized the ion balance (K⁺/Na⁺), and modulated the soil rhizosphere microbial community by increasing beneficial bacteria, such as Actinobacteria and Firmicutes. This study provides the first evidence that the synergistic effect of DA and PGPR contributes to enhanced salt tolerance in rice, offering a novel strategy for alleviating the adverse effects of salt stress on plant growth. Full article

Flavonoids serve as crucial plant antioxidants in drought tolerance, yet their antioxidant regulatory mechanisms within mycorrhizal plants remain unclear. In this study, using a two-factor design, trifoliate orange (Poncirus trifoliata (L.) Raf.) seedlings in the four-to-five-leaf stage were either inoculated with Funneliformis mosseae or not, and subjected to well-watered (70–75% of field maximum water-holding capacity) or drought stress (50–55% field maximum water-holding capacity) conditions for 10 weeks. Plant growth performance, photosynthetic physiology, leaf flavonoid content and their antioxidant capacity, reactive oxygen species levels, and activities and gene expression of key flavonoid biosynthesis enzymes were analyzed. Although drought stress significantly reduced root colonization and soil hyphal length, inoculation with F. mosseae consistently enhanced the biomass of leaves, stems, and roots, as well as root surface area and diameter, irrespective of soil moisture. Despite drought suppressing photosynthesis in mycorrhizal plants, F. mosseae substantially improved photosynthetic capacity (measured via gas exchange) and optimized photochemical efficiency (assessed by chlorophyll fluorescence) while reducing non-photochemical quenching (heat dissipation). Inoculation with F. mosseae elevated the total flavonoid content in leaves by 46.67% (well-watered) and 14.04% (drought), accompanied by significantly enhanced activities of key synthases such as phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), 4-coumarate:coA ligase (4CL), and cinnamate 4-hydroxylase (C4H), with increases ranging from 16.90 to 117.42% under drought. Quantitative real-time PCR revealed that both mycorrhization and drought upregulated the expression of PtPAL1, PtCHI, and Pt4CL genes, with soil moisture critically modulating mycorrhizal regulatory effects. In vitro assays showed that flavonoid extracts scavenged radicals at rates of 30.07–41.60% in hydroxyl radical (•OH), 71.89–78.06% in superoxide radical anion (O₂^•−), and 49.97–74.75% in 2,2-diphenyl-1-picrylhydrazyl (DPPH). Mycorrhizal symbiosis enhanced the antioxidant capacity of flavonoids, resulting in higher scavenging rates of •OH (19.07%), O₂^•− (5.00%), and DPPH (31.81%) under drought. Inoculated plants displayed reduced hydrogen peroxide (19.77%), O₂^•− (23.90%), and malondialdehyde (17.36%) levels. This study concludes that mycorrhizae promote the level of total flavonoids in trifoliate orange by accelerating the flavonoid biosynthesis pathway, hence reducing oxidative damage under drought. Full article

This study aims to select the most suitable submerged plants for the remediation and ecological rehabilitation of nutrient-enriched aquatic environments. The experiment selected Vallisneria natans, Myriophyllum verticillatum, and Elodea nuttallii as research objects. An artificial outdoor pot experiment was conducted with six different levels of ammonia nitrogen: 2, 4, 6, 8, 12, and 16 mg/L. The present study measured the physiological and growth parameters of submerged macrophytes under varying ammonia nitrogen concentrations. The response characteristics of plants to ammonia nitrogen stress were analyzed, and the tolerance thresholds of different submerged macrophyte species to ammonia nitrogen were determined. This enabled us to screen for ammonia nitrogen-tolerant pioneer species suitable for water ecological restoration in eutrophic water bodies. The experiment spanned 28 days. The results showed that the maximum suitable concentration and maximum tolerance concentration of ammonia nitrogen for Vallisneria natans, Myriophyllum verticillatum, and Elodea nuttallii were 2, 4, and 4 mg/L and 4, 12, and 8 mg/L. Submerged plants can grow normally within their maximum ammonia nitrogen tolerance concentration. When the concentration exceeds the maximum tolerance level, the growth of submerged plants is severely stressed by ammonia nitrogen. Low ammonia nitrogen concentrations promote the growth of submerged macrophyte biomass and chlorophyll content as well as the accumulation of dry matter in plants, while high ammonia nitrogen concentrations damage the antioxidant enzyme system and inhibit the growth of submerged plants. The tolerance of the three submerged macrophytes to ammonia nitrogen is as follows: Myriophyllum verticillatum > Elodea nuttallii > Vallisneria natans. Therefore, Myriophyllum verticillatum should be chosen as the ammonia nitrogen-tolerant pioneer species in the ecological restoration of eutrophic water bodies. The research results can provide a theoretical basis for the application of aquatic macrophytes in the treatment of eutrophic water bodies and ecological restoration. Full article

The urbanization-driven surge in kitchen waste necessitates optimized dry anaerobic digestion (DAD; total solids > 15%). Despite its valorization potential, this technology requires efficiency improvements due to mass transfer constraints. This study evaluated TS effects (15%, 20%, or 25%) on methane production. The TS = 20% system achieved peak cumulative methane yield (405.73 ± 11.71 mL/gVS), exceeding TS = 15% (348.09 ± 12.19 mL/gVS) and TS = 25% (293.08 ± 3.55 mL/gVS). This optimization was attributable to synergistic maintenance of metabolic equilibrium through autonomous pH recovery, rapid VFAs degradation, and enhanced TAN tolerance. Conversely, TS = 25% exhibited impaired mass transfer efficiency under high solids, causing VFAs accumulation, ammonia toxicity, and progressive pH decline to 7.5, indicating system destabilization. Organic degradation analysis confirmed superior conversion efficiency in TS = 20% through dynamic SPS–SPN equilibrium. Microbial analysis revealed enhanced metabolic efficiency via synergistic interactions between acetoclastic and hydrogenotrophic methanogens in TS = 20%. This research provides technical parameters for optimizing methane production in kitchen waste DAD systems. Full article

Plant growth-promoting rhizobacteria (PGPR) are eco-friendly and sustainable options for agrochemicals, particularly for enhancing crop productivity under stress conditions. The present research aims to isolate and characterize native PGPR from tomato rhizospheric soil and to evaluate their effectiveness as a dose-dependent response to enhance the growth of tomato seedlings. Out of 112 isolates, 10 bacterial strains were selected based on key PGPR traits, including indole-3-acetic acid (IAA), ammonia production, hydrogen cyanide (HCN), exopolysaccharide (EPS) synthesis, hydrolytic enzyme activity, potassium solubilization, antifungal activity against Fusarium oxysporum, and tolerance to pH and heat stress. Molecular identification via 16S rRNA gene sequencing confirmed that these isolates belong to the genera Serratia and Enterobacter. S. marcescens So-1 and Enterobacter sp. So-12 produced the highest levels of IAA (2.6–24.1 µg/mL). In vitro tomato seed germination tests using bacterial suspensions at three concentrations (10⁶, 10⁷, and 10⁸ CFU/mL) showed dose-dependent improvements, with T1 increasing germination up to 108.3% compared to the control. In polyhouse trials using cocopeat formulations, seedling growth improved noticeably. T2 increased the root length (28.3 ± 2.98 cm) by over 1560%, and the shoot length (35.7 ± 0.57 cm) increased by 55% against the control, whose root length is 1.7 ± 0.47. The chlorophyll amount of the treated leaves further showed significant results over the control. Collectively, these findings suggest that using native PGPR in a dose-dependent way can help tomato seedlings grow better and promote more sustainable crop production. Full article

The spotted longbarbel catfish, Hemibagrus guttatus, a nationally protected Class II species in China, faces increasing threats from habitat degradation. Recently, the spotted longbarbel catfish has gained attention as a promising aquaculture species, not only for its premium flesh quality but also for its potential role in conservation through sustainable captive breeding programs. Ammonia nitrogen (ammonia-N) is a ubiquitous byproduct of intensive farming and serves as the primary environmental stressor confronting aquatic species. Elucidating the ammonia-N tolerance of spotted longbarbel catfish constitutes a critical prerequisite for its successful domestication, which is the aim of this study. We demonstrate that ammonia-N stress significantly decreases the survival rate of spotted longbarbel catfish and induces tissue damage, including gill lamella proliferation, hepatocyte blurring, and renal necrosis. Transcriptomic analysis revealed that ammonia-N stress promotes the expression of genes related to endoplasmic reticulum stress, heat-shock proteins, immune response, and apoptosis, while inhibiting antioxidant-related genes and Wnt-related genes. Enzymatic assays indicate that ammonia-N stress inhibits the activities of multiple antioxidant enzymes, including SOD, CAT, GSH, GSH-Px, and T-AOC. Microbiome analysis showed that ammonia-N stress altered the intestinal microbial community by increasing harmful bacteria (e.g., Vibrio and Aeromonas) and suppressing beneficial bacteria (e.g., Cetobacterium and Lactococcus). These findings highlight the comprehensive negative impacts of ammonia-N on the health of the spotted longbarbel catfish and provide a theoretical basis for optimizing aquaculture conditions to support the sustainable protection and domestication of the spotted longbarbel catfish. Full article

This study examined the behavioral responses of Nile Tilapia (Oreochromis niloticus), a key aquaculture species, to ammonia stress using non-invasive image processing techniques. The experiment was conducted under controlled laboratory conditions and involved four groups exposed to ammonium chloride concentrations (0, 100, 200, and 400 mg·lt⁻¹). Movement trajectories of individual fish were recorded over 10 h using high-resolution cameras positioned above and beside glass tanks. Images were processed with the Optical Flow Farneback algorithm in Python, implemented in Visual Studio Code with OpenCV and NumPy libraries, achieving a 91.40% accuracy rate in tracking fish positions. The results revealed that increasing ammonia levels restricted movement areas while elevating movement irregularity and activity. The 0 mg·lt⁻¹ group utilized the glass tank homogeneously, covering 477 m. In contrast, the 100 mg·lt⁻¹ group showed clustering in specific areas (796 m). At 200 mg·lt⁻¹, clustering intensified, particularly along the glass tank’s left edge (744 m), and at 400 mg·lt⁻¹, fish exhibited severe restriction near the water surface with markedly increased activity (928 m). Statistical analyses using Kruskal–Wallis and Dunn tests confirmed significant differences between the 400 mg·lt⁻¹ group and others. No difference was observed between the 0 mg·lt⁻¹ and 100 mg·lt⁻¹ group, indicating tolerance to lower concentrations. The study highlights the importance of ammonia levels in water quality management and reveals the potential of image processing techniques for automation and stress monitoring in aquaculture. Full article

Topmouth Gudgeon (Pseudorasbora parva), a typical invasive fish worldwide, has successfully invaded various aquatic ecosystems and colonized saline–alkali waters from freshwater due to its broad environmental tolerances. However, the molecular mechanisms of adaptation to saline–alkali stress for P. parva remain poorly characterized. To explore the potential genetic mechanisms, we conducted differential gene expression analysis using gill transcriptome of wild P. parva populations collected from four waters with different salinity–alkalinity levels. Comparative transcriptomics analysis showed that DEGs involved in osmoregulation, ano6, cftr, aqp1, and aqp3, were down-regulated; DEGs related to ammonia excretion, Rhcg and Rhbg, were up-regulated; DEGs for acid–base accommodation, nhe2, slc4a1, and ca2, were down-regulated while ca4 was up-regulated; and immune-system-related DEGs, il8 and il17, were down- and up-regulated, respectively, in a high saline–alkaline water environment. The DEGs were enriched in multiple KEGG pathways, such as the ribosome, thermogenesis, oxidative phosphorylation, necroptosis, and HIF-1 signaling pathways. In addition, more DEGs were significantly enriched in immune-disease-related pathways in high saline–alkaline water populations. This suggests that P. parva exposed to chronic saline–alkali stress, despite survival, still needed immune system regulation to defend against potential diseases. These results revealed the gill molecular mechanisms underlying P. parva saline–alkaline adaptation and offered valuable insights into the development of saline–alkaline water aquaculture fisheries Full article

This study evaluated the physiological and biochemical responses of chickpea (Cicer arietinum L.) to foliar application of cineole, carvacrol, and thymol at concentrations of 500 and 1000 ppm. Carvacrol at 1000 ppm significantly enhanced fresh biomass (+15.4%) and aerial biomass (+46.2%), whereas thymol significantly reduced plant height (−20.2%) and overall biomass, yet notably increased chlorophyll content (+23.3%) and vitamin C levels (+41.4%) at the same concentration. Cineole significantly improved antioxidant capacity by increasing total phenolic content (+15.5% at 1000 ppm) and total flavonoid content (+19.1% at 500 ppm), but simultaneously decreased soluble protein synthesis and chlorophyll content (−39% at 500 ppm). Mineral analysis showed notable increases in calcium content following treatment with cineole (+30.5% at 1000 ppm) and carvacrol (+32% at 500 ppm), while thymol at 1000 ppm significantly reduced phosphorus, potassium, manganese, iron, copper, and zinc accumulation. Molecular docking and dynamic simulations revealed strong interactions of thymol and carvacrol with essential enzymes, specifically ascorbate peroxidase and phenylalanine ammonia-lyase, which are involved in antioxidant and phenolic metabolism pathways. These molecular interactions suggest potential contributions of thymol and carvacrol to plant stress resilience mechanisms, although further experimental validation is needed to confirm their roles in vivo. These findings emphasize the importance of optimizing monoterpene concentrations, indicating that carefully calibrated treatments could effectively enhance chickpea growth, nutritional quality, and stress tolerance within sustainable agricultural practices. Full article

Freshwater bivalves play essential ecological roles in ecosystems, but they are among the most threatened fauna worldwide. Despite receiving industrial and domestic wastes, the Guandu River is the main source of drinking water for more than nine million people in the Rio de Janeiro metropolitan region. This study aimed to assess how infaunal bivalves respond to water and sediment quality in the Guandu River basin. Samples were collected at 10 sites across reservoirs, lotic, and lentic systems during cold–dry and warm–rainy seasons. Four bivalves were identified: Anodontites trapesialis, Diplodon ellipticus, Corbicula fluminea (non-native), and C. largillierti (non-native). Native species were restricted to two lentic sites at Guandu Lagoon, with the poorest environmental quality, significantly affected by high chlorophyll a and ammonia in the water. In contrast, C. fluminea was widely distributed and more abundant in the basin but restricted to less degraded sites, suggesting a lower tolerance to environmental pollution. Multivariate analyses indicated significant differences in environmental conditions and species–environment correlation. The non-native species spread and poor environmental quality threaten native bivalves in the Guandu River basin, leading them to a local extinction risk. Results highlight the need for effective management and conservation actions to protect biodiversity in tropical river basins. Full article

The aim of this study was to investigate the effects of sodium butyrate (SB) on growth performance, digestive ability, blood health, and ammonia tolerance of largemouth bass. During the experiment, largemouth bass were fed different diets (0.00%, 0.50% and 1.00% SB) followed by a 96-h ammonia challenge. In this study, dietary supplementation of SB can improve the growth (weight gain rate increased; GH and IGF 1 genes up-regulated) of largemouth bass. The addition of SB also significantly increased serum total protein, albumin and globulin contents and reduced triglycerides, cholesterol and aspartate transaminase contents. The digestive ability (pepsin, lipase, amylase, alkaline phosphatase, creatine kinase, gamma-glutamyltranspeptidase, sodium-potassium adenosine triphosphatase, villus height and muscular thickness increased) was significantly higher in the 0.50% and 1.00% SB groups. SB also improved the anti-inflammatory capacity (IL 1 and IL 8 genes down-regulated) of largemouth bass. The addition of SB to feed significantly reduced the cumulative mortality rate after 96 h of ammonia stress. SB significantly increased liver ammonia metabolism enzyme (arginase, argininosuccinate synthetase, ornithine transcarboxylase and argininosuccinate lyase) and inducible nitric oxide synthase activity, and significantly decreased the neuronal nitric oxide synthase activity. The results indicate that dietary supplementation of SB can promote growth and improve digestive ability, blood health, and ammonia tolerance in largemouth bass. Full article

Nitrogen (N) cycling in agroecosystems is a complex process regulated by both biological and agronomic factors, with ammonia-oxidizing archaea (AOA) and bacteria (AOB) playing pivotal roles in nitrification. Despite extensive fertilizer applications to achieve maximum crop yields, nitrogen use efficiency (NUE) remains less than ideal, with substantial losses contributing to environmental degradation. This review synthesizes current knowledge on plant-mediated and fertilization-induced shifts in ammonia-oxidizer communities and their implications on nitrogen cycling. We highlight the differential ecological niches of AOA and AOB, emphasizing their responses to plant community composition, root exudates, and allelopathic compounds. Fertilization regimes of inorganic nitrogen inputs and biological nitrification inhibition (BNI) are examined in the context of microbial adaptation and ammonia tolerance. Our review highlights the need for integrated nitrogen management strategies comprising optimized fertilization timing, nitrification inhibitors, and plant–microbe interactions in order to optimize NUE and mitigate nitrogen losses. Future research directions must involve applications of metagenomic and isotopic tracing techniques to unravel the mechanistic AOA and AOB pathways that are involved in regulating these dynamics. An improved understanding of these microbial interactions will inform the creation of more sustainable agricultural systems that aim to optimize nitrogen retention and reduce environmental footprint. Full article

High temperatures in summer often trigger disease outbreaks in shrimp, resulting in significant economic losses. To investigate the heat tolerance mechanisms of Penaeus monodon, juvenile tiger shrimp were subjected to a high-temperature stress of 38 °C for 144 h. The cumulative survival rate of shrimp sharply decreased to 5.29% in the later 144 h. The heat-sensitive shrimps (S group) were collected in the first 24 h, while those that survived beyond 120 h were collected as the heat-tolerant group (T group). The hepatopancreas of two groups was subjected to transcriptomic and metabolomic analysis. The results revealed that, compared to the S group, the T group exhibited a total of 3527 DEGs, including 2199 upregulated and 1328 downregulated genes. Additionally, 353 DAMs were identified in the T group, with 75 metabolites showing increased levels and 278 metabolites displaying decreased levels. The results revealed that the mechanisms of heat tolerance involve energy supply strategies, immune system regulation, amino acid metabolism, and glutathione metabolism. Energy supply strategies include the digestion and absorption of carbohydrates and proteins, glycolysis/gluconeogenesis, fructose and mannose metabolism, and pyruvate metabolism, all of which collectively meet energy demands in high-temperature environments. The immune system is regulated by C-type lectin receptor pathways and IL-17 signaling pathways, which together coordinate innate immunity to prevent pathogen invasion. In amino acid metabolism, various glycogenic amino acids, such as histidine, phenylalanine, valine, and serine, are metabolized for energy, while excess ammonia is converted to γ-glutamyl-glutamate and L-glutamate to mitigate ammonia accumulation. Combined transcriptomic and metabolomic analyses further indicate that glutathione metabolism plays a crucial role in the adaptation of P. monodon to high-temperature environments. This study explains the high-temperature tolerance mechanism of P. monodon from the aspects of gene expression regulation and material metabolism regulation and also provides a scientific basis and basic data for the selection and breeding of new varieties of P. monodon with a high-temperature tolerance. Full article

The development of sustainable seed coating formulations is essential to enhance crop performance while reducing reliance on synthetic inputs. This study evaluates biochar-enriched coatings incorporating olive pomace, buffalo digestate, and microbial consortia from Fagus, Quercus, and Pinus forest litters, including Trichoderma harzianum, for their effects on seed germination and plant growth. Four crops (Diplotaxis tenuifolia, Lactuca sativa, Solanum lycopersicum, and Zea mays) were tested through germination assays and field trials. Treatments containing digestate or pomace alone significantly reduced germination and seedling growth in D. tenuifolia and L. sativa (below 25%, compared to control), due to the phytotoxic effects of ammonia, salts, and polyphenols. In contrast, biochar-based coatings mitigated these effects, enhancing germination and root elongation. The addition of T. harzianum further improved seedling establishment, likely by enhancing nutrient uptake and suppressing soilborne pathogens, with increases exceeding 100% (compared to control). Field trials confirmed these findings, showing that biochar–T. harzianum combinations improved both shoot and root biomass, particularly in L. sativa and S. lycopersicum. Z. mays displayed greater tolerance to raw by-products, though biochar remained essential for optimal growth. While forest-derived microbial consortia supported microbial balance, their effect on biomass was less pronounced. These results highlight the potential of biochar-based coatings, especially when combined with T. harzianum, as sustainable alternatives to conventional seed treatments. Full article