Activities Of Key Enzymes Research Articles

A Descriptive Review of the Antioxidant Effects and Mechanisms of Action of Berberine and Silymarin.

Oxidative stress is a key factor in the development of chronic diseases such as type 2 diabetes, cardiovascular diseases, and liver disorders. Antioxidant therapies that target oxidative damage show significant promise in preventing and treating these conditions. Berberine, an alkaloid derived from various plants in the Berberidaceae family, enhances cellular defenses against oxidative stress through several mechanisms. It activates the AMP-activated protein kinase (AMPK) pathway, which reduces mitochondrial reactive oxygen species (ROS) production and improves energy metabolism. Furthermore, it boosts the activity of key antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), thus protecting cells from oxidative damage. These actions make berberine effective in managing diseases like type 2 diabetes, cardiovascular conditions, and neurodegenerative disorders. Silymarin, a flavonolignan complex derived from Silybum marianum, is particularly effective for liver protection. It activates the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, enhancing antioxidant enzyme expression and stabilizing mitochondrial membranes. Additionally, silymarin reduces the formation of ROS by chelating metal ions, and it also diminishes inflammation. This makes it beneficial for conditions like non-alcoholic fatty liver disease (NAFLD) and alcohol-related liver disorders. This review aims to highlight the distinct mechanisms by which berberine and silymarin exert their antioxidant effects.

Starch-related structural basis and enzymatic mechanism of the different appearances of soft rice

To investigate the fine starch structure characteristics and formation mechanism of high-quality appearance soft rice, two high-quality and low-quality soft rice varieties (HA-SR and LA-SR, respectively) were selected. Differences in appearance quality, fine starch structure, and activity of key enzymes involved in starch synthesis during the grain-filling stage were compared. The results showed that compared with LA-SR, HA-SR were less chalky, more transparent, had larger starch grains, a lower content of shorter chains (DP 6–24), a higher content of longer chains (DP ≥ 25), lower relative crystallinity, fewer ordered structures, more amorphous structures and larger thicknesses of semi-crystalline lamellae. In terms of amylase activity during the grain-filling stage, the AGPase and GBSS activities of HA-SR were higher, and the SBE activity of HA-SR was lower compared to LA-SR. In conclusion, higher AGPase activity can produce a higher filling rate resulting in fuller starch grain in soft rice. Fuller starch grains reduce the chalkiness of soft rice. Higher AGPase and GBSS activities and lower SBE activity can result in soft rice with more long-branched and less short-branched amylopectin. Thus, soft rice has lower relative crystallinity and less ordered structure. These structures may facilitate reduce grain chalkiness and improve grain transparency.

Effects of Efficient Ethylene Remover on the Lignification of Fresh Faba Bean (Vicia faba L.) during Storage.

Postharvest ethylene accumulation and lignification are significant issues affecting the storage quality of fresh faba beans, resulting in rapid quality decline. However, there is still a lack of effective preservation methods to preserve the quality of faba beans during storage. This study aimed to investigate the regulation of lignification in faba beans during storage using a high-efficiency ethylene remover (HEER), examining physiological responses, key enzyme activities, and transcriptomic changes. Results showed that the HEER treatment inhibited the lignification, reducing it by 45% and lowering the respiratory rate of fresh pods by 32.8% during storage. Additionally, the HEER treatment suppressed respiration rates and the activities of lignin synthesis-related enzymes, including phenylalanine ammonia-lyase (from 353.73 to 246.60 U/g), cinnamic acid-4-hydroxylase (from 635.86 to 125.00 U/g), 4-coumarate: coenzyme A ligase (from 1008.57 to 516.52 U/g), and cinnamyl-alcohol dehydrogenase (from 129.42 to 37.12 U/g), thus slowing lignin accumulation. During storage, the hardness of fresh faba bean increased by 9.79% from the initial period, being 1.44 times higher than that of HEER. On days 8 and 16 of storage, the respiratory rate of the treated beans decreased by 24.38% and 4.12%, respectively. Physiological and enzyme activity analyses indicated that HEER treatment-induced increase in hardness was associated with the phenylpropanoid metabolic pathway. Moreover, the HEER significantly down-regulated the expression of several key genes, namely FaPAL, FaC4H, and FaCAD. This study helps to deepen the understanding of the inhibition of lignification by HEER and provide new insights for the development of preservation technology of faba bean.

Fluorescence lifetime imaging of human pancreatic lipase activity using a novel probe for early diagnosis of severe acute pancreatitis

Severe Acute Pancreatitis, a serious condition caused by factors such as gallstones and chronic excessive alcohol consumption, with a very high mortality rate. Human pancreatic lipase (hPL) is a key digestive enzyme and abnormal activity levels of this enzyme are important indicators for diagnosing and monitoring pancreatic diseases. A fluorescent probe, LPP, has been developed to monitor the activity of hPL, especially in cases of SAP. The probe is based on cyanine isoindole derivatives, in vitro experiments confirmed the high specificity and sensitivity of the probe, with a detection limit of 0.012 U/mL, reactions completed within 10 min, and effective monitoring of pancreatic lipase activity in various biological samples. The stability and low cytotoxicity of LPP make it suitable for clinical applications, providing new tools and perspectives for the research and treatment of pancreatic diseases and related metabolic abnormalities. In addition, the change in fluorescence lifetime after the reaction of the probe with lipase allows for fluorescence lifetime imaging (FLIM), effectively monitoring the dynamic changes of hPL and enabling early diagnosis and monitoring of pancreatitis. This research not only enhances the understanding of pancreatic lipase activity detection but also has the potential to improve the diagnostics and treatment of pancreatitis.

Novel insights on ecological responses of short- and long-chain perfluorocarboxylic acids in constructed wetlands coupled with modified basalt fiber bio-nest

The first investigation based on constructed wetlands coupled with modified basalt fiber bio-nest (MBF-CWs) was performed under exposure of short- and long-chain perfluorocarboxylic acids (PFCAs). In general, both perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) caused significant decline of chemical oxygen demand removal by 10.83 % and 4.73 %. However, only PFOA led to marked inhibition on total phosphorus removal by 12.51 % in whole duration. Suppression of removal performance resulted from side impacts on microbes by PFOA. For instance, activities of key enzymes like dehydrogenase (DHA), urease (URE), and phosphatase (PST) decreased by 52.77 %, 40.70 %, and 56.94 % in maximum under PFOA stress, while URE could alleviate over time. By contrast, distinct inhibition was only found on PST in later phases with PFBA exposure. PFCAs had adverse influence on alpha diversity of MBF-CWs, particularly long-chain PFOA. Both PFCAs caused enrichment of Proteobacteria, owing to increase of Gammaproteobacteria and Plasticicumulans by 22.04–35.79 % and 22.91–219.77 %. Nevertheless, some dominant phyla (like Bacteroidota and Acidobacteriota) and genera (like SC-I-84, Thauera, Subgroup_10, and Ellin6067) were only suppressed by PFOA, causing more hazards to microbial decontamination than PFBA did. As for plants, chlorophyll contents tend to decrease with PFOA treatment. Whereas, higher antioxidase activities and more lipid peroxidation products were uncovered in PFOA group, demonstrating more reactive oxygen species brought by long-chain PFCAs. This work offered new findings about ecological effects of MBF-CWs under PFCAs exposure, evaluating stability and sustainability of MBF-CW systems to treat sewage containing complex PFCAs.

3D-printed controllable bio-accelerators with sustained release property to boost chromium (VI) inhibited denitrification recovery

Although soluble bio-accelerators have proven effective in mitigating Cr(VI) inhibition within denitrification system, issues persist in immobilizing bio-accelerators and making them slow-release for sustained regulation. In this study, a novel strategy was proposed to fabricate immobilized bio-accelerators with controlled structure, sustained release property by 3D printing technology. Notably, the sustained release of bio-accelerators from 3D-printed bio-accelerators (3DP-B) lasted for at least 144 h. Compared to control group, 3DP-B with basic components (3DP-BB) shortened the recovery time by 1.4 folds, and the COD and NO3--N removal efficiency was 36.5 % and 38.0 % higher than that of natural recovery. Correspondingly, the activity of key enzymes (nitrate reductase, nitrite reductase, nitric oxide reductase, and nitrous oxide reductase), electron transfer system activity and extracellular polymer substances of denitrification biofilm maintained at relatively high levels. Furthermore, introducing 60 mg·L-1 anthraquinone-2,6-disulfonate (AQDS) into the ink showed noticeable superiority on the bio-inhibition release over 1000 mg·L-1 AQDS. The released AQDS facilitated the electron transport capacity by 1.25 times compared with control group. The groundbreaking findings of this study could advance the development of 3D printing technology and utilization of bio-accelerators in the field of wastewater treatment.

Dietary nicotinamide improves growth performance and ameliorates liver lipid profiles by alleviating glycerophospholipid and sphingolipids metabolism in swamp eel (Monopterus albus)

The effect of dietary niacinamide (NAM) on the growth performance and liver lipid metabolism of swamp eel have been poorly investigated. Therefore, a 120-day feeding trial was conducted to provide different levels of NAM in diet and an untargeted lipidome analysis was performed to address this subject. We found that dietary NAM improved the growth performance of swamp eel. It also decreased the contents of glucose and lipids, including glucose, glycogen, TG, and NEFA, as well as fat accumulation in liver, but increased HDL-C content. We speculated that NAM inhibited lipid accumulation in liver by decreasing the key enzyme activity of LPL, HL and LPS. Fatty acid profile analysis showed that the contents of MUFA and PUFA, such as palmitoleic acid, oleic acid, and eicosapentaenoic acid were significantly increased, while the contents of SFA, such as myristic acid, stearic acid, and palmitic acid were decreased in liver by dietary NAM. Lipidome analysis also indicated that the majority of differential lipid metabolites belonged to glycerophospholipids and sphingolipids, which were enriched in the pathways of insulin resistance, adipocytokine signaling pathway, cholesterol metabolism, fat digestion and absorption, lipid and atherosclerosis, and lipid cell lipolysis regulation. These findings gave scientific evidences and novel insights into the metabolic responses to dietary NAM in swamp eel, and provided basic knowledge for using NAM as a feed additive in swamp eel production.

Performance of a novel Built-in Static Magnetic Field – Biological Aerated Filter (BSMF–BAF) for treating high-salt textile dyeing wastewater

High-salt textile dyeing wastewater is difficult to treat. Magnetic fields can enhance the biodegradation capacity and extreme environmental adaptabilities of microorganisms. Thus, magnetically enhanced bioreactors are expected to improve the treatment efficiency and stability of high-salt textile dyeing wastewater. Accordingly, a novel Built-in Static Magnetic Field – Biological Aerated Filter (BSMF–BAF) was constructed and investigated for treating actual high-salt textile dyeing wastewater in this study. Two other BAFs packed with traditional and magnetic ceramsite carriers, respectively, were simultaneously operated for comparison. The removal of color, chemical oxygen demand (COD), suspended solid (SS) and acute toxicity were monitored. The activities of key enzymes and microbial community structure were analyzed to reveal possible mechanisms for improving the treatment efficiency of traditional BAF using the BSMF. The results showed that the BSMF–BAF possessed the highest removal efficiencies of color, COD, SS and acute toxicity among the three BAFs. The BSMF induced significant increases in the activities of azoreductase and lignin peroxidase, which were responsible for the degradation of azo compounds in the wastewater and the detoxification of toxic intermediates, respectively. Additionally, the BSMF induced the relative enrichment of potentially effective bacteria and fungi, and it maintained a relatively high abundance of fungi in the microbial community, resulting in a high treatment efficiency.

Modulation of the Cardiovascular Risk in Type 1 Diabetic Rats by Endurance Training in Combination with the Prebiotic Xylooligosaccharide.

Diabetic cardiomyopathy is a major etiological factor in heart failure in diabetic patients, characterized by mitochondrial oxidative metabolism dysfunction, myocardial fibrosis, and marked glycogen elevation. The aim of the present study is to evaluate the effect of endurance training and prebiotic xylooligosaccharide (XOS) on the activity of key oxidative enzymes, myocardial collagen, and glycogen distribution as well as some serum biochemical risk markers in streptozotocin-induced type 1 diabetic rats. Male Wistar rats (n = 36) were divided into four diabetic groups (n = 9): sedentary diabetic rats on a normal diet (SDN), trained diabetic rats on a normal diet (TDN), trained diabetic rats on a normal diet with an XOS supplement (TD-XOS), and sedentary diabetic rats with an XOS supplement (SD-XOS). The results show that aerobic training managed to increase the enzyme activity of respiratory Complex I and II and the lactate dehydrogenase in the cardiomyocytes of the diabetic rats. Furthermore, the combination of exercise and XOS significantly decreased the collagen and glycogen content. No significant effects on blood pressure, heart rate or markers of inflammation were detected. These results demonstrate the beneficial effects of exercise, alone or in combination with XOS, on the cardiac mitochondrial enzymology and histopathology of diabetic rats.

Ferric uptake regulator (Fur) in Vibrio mimicus acts as an activator of citrate cycle and oxidative phosphorylation pathways, while enhancing virulence potential

Ferric uptake regulator (Fur) is a crucial bacterial regulator that controls the uptake of iron by bacteria, hence influencing their survival and pathogenicity. Vibrio mimicus is an epidemic pathogen that is harmful to aquatic animals and human health, with the characteristics of rapid onset and high mortality after infecting the fish. At present, the function and mechanism of Fur in V. mimicus are still unclear. In this study, the fur gene deletion strain and complementation strain of V. mimicus were constructed. Following fur deletion, proteomic analysis revealed that the abundance of 258 proteins was considerably up-regulated while the abundance of 307 proteins was dramatically down-regulated. The primary roles of these differentially expressed proteins were in a variety of pathways, including virulence, metabolism, enzymes, and so on. Among them, citrate cycle and oxidative phosphorylation were the main pathways affected by Fur. The activities of key enzymes in these two pathways were assessed. The results indicated a decrease in the activities of respiratory chain complexes II and IV, succinate dehydrogenase (SDH), and α-ketoglutarate dehydrogenase (α-KGDH) in the Δfur strain. Conversely, the activity of isocitrate dehydrogenase (NAD-IDH) was increased. Phenotypic characterization showed that the Δfur strain exhibited delayed growth, reduced motility, defective biofilm formation, decreased resistance to oxidative stress, increased adhesion, and decreased virulence. Besides, the LD50 of the Δfur strain was 31-fold higher than that of the WT strain. These results indicate that Fur serves as an activator for the citrate cycle and oxidative phosphorylation pathway in V. mimicus, and contributing to its virulence. Our findings enhance the understanding of the biological functions of Fur and lay the groundwork for further investigation into the regulatory mechanisms of Fur in V. mimicus.

From reduction to rebalancing: Insights into the long-term effects of sediment dredging on nitrogen transformations in river ecosystems

Although sediment dredging is a widely employed water management and restoration technique for the removal of internal nitrogen (N), the long-term effects of dredging on N transformation in dredged rivers remain largely undetermined. In this study, we investigated the effects of dredging on N transformation processes spanning three years at ten sites in the purple-soil watershed within the middle reaches of the Fu River Basin. We combined isotopic and molecular techniques to provide novel insights into the interactions associated with microbial utilization capacities between sediment and river water before, during, and after dredging. Initially, dredging was found to significantly reduce the total nitrogen content by approximately 75 %, although over time, there was a slight increase in concentrations. Secondly, significant reductions in microbial richness and diversity were detected in both river water and sediment, with 39 classes reduced, 12 new classes emerging, and an increase in archaea, reshaping the microbial community. Lastly, dredging was found to promote a significant shift in functional contributions, with increases in the abundance of key enzyme activities (1.7.5.1 and 1.7.2.5) and denitrification genes (nirK, norB, and nosZ). This enhancement notably promoted denitrification and dissimilatory nitrate reduction to ammonium (DNRA), accompanied by significant environmental changes in sediment and river water. These changes facilitated the removal of nitrates in the Xiangshuitan watershed. Our study overcomes the limitations associated with watershed and microenvironment scales, providing insights into the mechanisms where by dredging activities influence the interplay between external and internal N transformations.

Zinc oxide nanoparticles reduce cadmium accumulation in hydroponic lettuce (Lactuca sativa L.) by increasing photosynthetic capacity and regulating phenylpropane metabolism

Due to the continuous production of industrial wastes and the excessive use of chemical fertilizers and pesticides, severe cadmium (Cd) pollution in soil has occurred globally. This study investigated the impacts of incorporating zinc oxide nanoparticles (ZnONPs) into hydroponically grown lettuce (Lactuca sativa) under cadmium stress conditions, to seek effective methods to minimize Cd buildup in green leafy vegetables. The results showed that 1 mg/L of Cd significantly inhibited lettuce growth, decreasing in leaves (29 %) and roots (33 %) biomass. However, when lettuce was exposed to 2.5 mg/L ZnONPs under cadmium stress, the growth, chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), actual photochemical efficiency of PSII (φPSII), and activity of key enzymes in photosynthesis were all significantly enhanced. Furthermore, ZnONPs significantly decreased the accumulation of Cd in lettuce leaves (36 %) and roots (13 %). They altered the subcellular distribution and chemical morphology of Cd in lettuce by modifying the composition of cell walls (such as pectin content) and the levels of phenolic compounds, resulting in a reduction of 27 % in Cd translocation from roots to leaves. RNA sequencing yielded 45.9 × 107 and 53.4 × 107 clean reads from plant leaves and roots in control (T0), Cd (T1), Cd+ZnONPs (T2), and ZnONPs (T3) treatment groups respectively, and 3614 and 1873 differentially expressed genes (DEGs) were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis identified photosynthesis, carbon fixation, and phenylpropanoid metabolism as the main causes of ZnONPs-mediated alleviation of Cd stress in lettuce. Specifically, the DEGs identified included 12 associated with photosystem I, 13 with photosystem II and 23 DEGs with the carbon fixation pathway of photosynthesis. Additionally, DEGs related to phenylalanine ammonia-lyase, caffeoyl CoA 3-O-methyltransferase, peroxidase, 4-coumarate-CoA ligase, hydroxycinnamoyl transferase, and cytochrome P450 proteins were also identified. Therefore, further research is recommended to elucidate the molecular mechanisms by which ZnONPs reduce Cd absorption in lettuce through phenolic acid components in the phenylpropanoid metabolism pathway. Overall, treatments with ZnONPs are recommended to effectively reduce Cd accumulation in the edible portion of lettuce.

Hydrochloric acid-modified biochar enhances nitrogen retention and microbial diversity in mollisols

The annual decline in the quality of China's mollisols and associated nitrogen loss necessitates effective interventions. This study investigates the effects of hydrochloric acid-modified biochar (BC-H700), derived from corn straw, on nitrogen retention and microbial diversity in mollisols through pot experiments. Through 100 days of continuous study found the application of 6 % BC-H700 significantly improved soil properties, increasing pH by 18.60 %, organic matter by 1.6 %, ammonium nitrogen by 26.96 %, and nitrate nitrogen by 23.04 %. By inquiring impact of BC-H700 on microbial enzyme activities in 60-day revealing BC-H700 also enhanced the activities of key nitrogen-transforming enzymes (AMO, NOR, NOS) and functional genes (nirK, norB, nosZ) while reducing narG gene abundance and NR enzyme activity. These changes indicate that BC-H700 promotes nitrification, inhibits denitrification, enhances nitrogen retention, and reduces N2O emissions. Furthermore, BC-H700 improved microbial diversity, increasing the abundance of beneficial bacteria such as Actinobacteria, Proteobacteria, Nitrospirae, and Gemmatimonadetes. The main environmental factors affecting soil bacterial community structure were identified as organic matter, NO3-, NO2-, AMO, NOR, and NOS. Overall, BC-H700 facilitates nitrogen transformation and retention through complex interactions with soil properties and microbes. This study contributes to understanding biochar's role in soil nitrogen management and offers practical insights for improving mollisol health.

Microalgal and Cyanobacterial Biomasses Modified the Activity of Extracellular Products from Bacillus pumilus: An In Vitro and In Vivo Assessment.

This study investigates the postbiotic potential of extracellular products (ECPs) from Bacillus pumilus strains cultivated on microalgae-supplemented media. We assessed enzymatic and antimicrobial activities to select ECPs that enhance the digestive processes in gilthead seabream. Additionally, we explored the in vitro enzymatic capacity of the chosen postbiotics to hydrolyze macromolecules in microalgae. Finally, a feeding trial was conducted to determine the in vivo effects of the ECPs on Sparus aurata. In vitro enzymatic assays demonstrated diverse hydrolytic capacities among ECPs. All conditions exhibited antimicrobial activity against Photobacterium damselae subsp. piscicida, with variation in inhibitory effects against Vibrio harveyi and Tenacibaculum maritimum. Furthermore, in vitro assays revealed differences in protein hydrolysis and soluble protein concentration, influencing amino acid and reducing sugar release from microalgal biomass. These analyses facilitated a selection to test ECPs in vivo. Lastly, the in vivo experiment revealed no differences in the growth performance, nutrient utilization, and general metabolism of S. aurata fed the experimental diets. Dietary inclusion of postbiotics increased the activity of key digestive enzymes in fish compared to the control group, and particularly, values increased significantly when the fish were fed with the ECP-nanoparticulate-supplemented diet. In conclusion, the inclusion of microalgae in the culture media significantly influences the activity of extracellular products from B. pumilus strains, as evidenced in both in vitro and in vivo assays.

Effect of postharvest cold storage and subsequent shelf-life on fruit quality and endogenous phytohormones in nectarine fruit

Cold storage is the main approach to extend the postharvest storage period of nectarines. The objective of this study was to investigate fruit quality (flavor and nutrition) and endogenous phytohormone changes and their related transcriptional changes in nectarine fruit after cold storage and subsequent shelf-life, which was performed metabolome, transcriptome and physiological analysis. Cold storage led to irreversible flavor loss due to the inhibition of aroma biosynthesis genes at low temperature. Sugar and organic acid content was affected, with an increase in glucose, fructose and malic acid, and a decrease in sorbitol and citric acid after cold storage or shelf-life. For fruit nutritional quality, total flavonoids or total carotenoids was not significantly affected by cold storage, whereas shelf-life process enhanced their accumulation. The activities of key enzymes for flavonoid biosynthesis, PAL and C4H, were enhanced during the shelf-life process, resulting in a significant increase in flavonoids and enhanced free radicals scavenging capacity. Meanwhile, shelf-life process increased carotenoids content by improving the expression of carotenoid biosynthesis genes PSY, ZDS and ZISO. Additionally, cold storage significantly increased the IAA content and ethylene production, thereby inducing the up-regulation of related signaling transduction genes. The shelf-life process further increased ethylene production, as well as salicylic acid and jasmonic acid content. This study unravels these crucial physiological and associated transcriptional changes of nectarines after cold storage, and may provide a theoretical foundation for improving fruit quality of peaches after cold storage.

Regulatory mechanism of methyl jasmonate and methyl dihydrojasmonate in enhancing aroma in 'Cabernet Gernischt' via the lipoxygenase pathway.

The present study explored the effects of pre-harvest methyl jasmonates spraying on the volatiles of 'Cabernet Gernischt' grapes through the lipoxygenase pathway. Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry and an enzyme-linked immunosorbent assay were utilized to analyze volatile metabolites and key enzyme activities following methyl jasmonates application. Total RNA extraction and cDNA library construction were followed by transcriptome sequencing. The application of 0.1 mmol L-1 methyl jasmonate and 5 mmol L-1 methyl dihydrojasmonate significantly increased the levels of C6 compounds in 'Cabernet Gernischt' berries, and also enhanced the utilization of unsaturated fatty acids as precursors in the lipoxygenase-hydroperoxides lyase pathway. The up-regulated expression of VvADH1, VvADH2, VvHPL and VvLOX2S genes led to modulations in enzyme activity, thereby enhancing the berries's aromatic profile. There was a significant correlation between linoleic and linolenic acids (i.e. the precursors of the lipoxygenase pathway) and the activities and metabolites of key enzymes. The optimal concentration of methyl jasmonates treatment favorably influences the accumulation of green leaf volatiles in 'Cabernet Gernischt' grape. © 2024 Society of Chemical Industry.

Long-term contamination of decabromodiphenyl ether reduces sediment multifunctionality: Insights from nutrient cycling, microbial ecological clusters, and microbial co-occurrence patterns

Despite the widespread detection of polybrominated diphenyl ethers in aquatic ecosystems, their long-term effects on sediment multifunctionality remain unclear. Herein, a 360-day microcosm experiment was conducted to investigate how decabromodiphenyl ether (BDE-209) contamination at different levels (0.2, 2, and 20 mg/kg dry weight) affects sediment multifunctionality, focusing on carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling. Results showed that BDE-209 significantly increased sediment total organic carbon, nitrate, ammonium, available phosphorus, and sulfide concentrations, but decreased sulfate. Additionally, BDE-209 significantly altered key enzyme activities related to nutrient cycling. Bacterial community dissimilarity was positively correlated with nutrient variability. Long-term BDE-209 exposure inhibited C degradation, P transport and regulation, and most N metabolic pathways, but enhanced C fixation, methanogenesis, organic P mineralization, inorganic P solubilization, and dissimilatory sulfate reduction pathways. These changes were mainly regulated by microbial ecological clusters and keystone taxa. Overall, sediment multifunctionality declined under BDE-209 stress, primarily related to microbial co-occurrence network complexity and ecological cluster diversity. Interestingly, sediment C and N cycling had greater impacts on multifunctionality than P and S cycling. This study provides crucial insights into the key factors altering multifunctionality in contaminated sediments, which will aid pollution control and mitigation in aquatic ecosystems.

Nitrogen Nutrition-Induced Changes in Macronutrient Content and Their Indirect Effect on N-Metabolism Via an Impact on Key N-Assimilating Enzymes in Bread Wheat (Triticum aestivum L.)

Judicious application of nitrogen (N) fertilizers in crop production is critical for reducing the nitrate pollution of groundwater and greenhouse gas emissions. It is, thus, important to improve the nitrogen use efficiency under the reduced application of nitrogen. A genotypic variation in N-uptake and N-use efficiency particularly under low N-input conditions exists across crops that can be deciphered and exploited for environmentally sustainable farming without any significant penalty of yield and quality. The present research conducted under the nutrient solution culture aimed to explore the inherent variability in the growth response of ten genetically diverse wheat varieties to low fertilizer N-application (N-, 10 μM N) in comparison to N sufficient control (N+, 8.5 mM N) viz., a viz., the activity of various key N-assimilating enzymes and to delineate the indirect effect of low N on uptake and partitioning of other major macronutrients viz., P, K, S, which may indirectly regulate the N-use efficiency. A notable increase in sulfur, potassium, and phosphorus content was observed under nitrogen-deficient conditions. Varieties such as Carnamah and HD 2824 exhibit a significant increase in shoot phosphorus content, emphasizing their potential to optimize phosphorus acquisition and utilization efficiency under nutrient-limited conditions. The findings highlight the complex interplay between nutrient availability and plant responses, showcasing varietal-specific adaptations to nitrogen limitations.

Enhancing yield of modern maize (ZeamaysL.) hybrids through the optimization of population photosynthetic capacity and light-nitrogen efficiency under high density

Due to the breeding of dense-resistant and lodging-resistant varieties in maize production, dense planting has become an effective means for achieving high and stable yields, while excellent hybrids are a prerequisite for reasonable dense planting in maize production. Nonetheless, the photosynthetic mechanism of improving plant density tolerance of maize hybrids released at different era in China remains unclear. This study aims to investigate the 40-year breeding effort for enhanced photosynthetic trait at different densities, and elucidate the physiological and ecological mechanisms of improving the density tolerance of maize hybrids. We conducted a 3-year study in 2019, 2020, and 2021. From 1970 to 2009, a comparison was made between the eight major hybrids promoted in China, divided into four decades, under three planting densities (45,000 (D1), 67,500 (D2), and 90,000 (D3) plants ha−1). At high density, modern hybrids had more rational canopy structure and leaf photosynthetic performance compared with old hybrids and specific leaf nitrogen has decreased slightly. Among all treatments, the modern hybrids (2000s) were able to maintain higher net photosynthetic rate and photosynthetic nitrogen utilization efficiency (PNUE) at D3 density, and therefore possessed the highest grain yield (GY), which was 118.47% higher than that of the old hybrids (1970s). Leaf area duration after anthesis, total chlorophyll content, photosynthesis key enzyme activities, and maximum efficiency of PSII photochemistry were all positively correlated with GY, with PNUE was more significantly correlated with GY indeed and is a key indicator for maize hybrids optimization. Based on these results, breeders should continue to conduct hybrid selections under adverse and high-density conditions, focusing on the optimization of population structure and the continuous improvement of photosynthetic capacity, searching for the optimal leaf nitrogen-content status, so as to select and breed high-yielding and density-tolerance hybrids, which resulted in a sustained increase in maize GY.

Daily rhythm in feeding behavior and digestive processes in totoaba (Totoaba macdonaldi) under commercial farming conditions

To identify daily changes in the digestive physiology of Totoaba macdonaldi, the feed intake, activity (pepsin, trypsin, chymotrypsin, lipase, amylase, and L-aminopeptidase), and gene expression (aminopeptidase and maltase-glucoamylase) of key digestive enzymes were measured in the intestine and the pyloric caeca. Fish were fed for three weeks every four hours during the light period to apparent satiation, and samples were taken every four hours throughout a 24-h cycle under a 12:12 L:D photoperiod. The feed consumption steadily increased until the third feeding (16:00 h, ZT-8) and decreased significantly towards the end of the day. The activity of pepsin and alkaline enzymes (trypsin, chymotrypsin, lipase, amylase, and L-aminopeptidase) exhibited a pattern dependent on the presence of feed, showing a significant reduction during the hours of darkness (ZT-12 to ZT-24). Expression of the intestinal brush border enzyme (L-aminopeptidase) increased during the darkness period in anticipation of the feed ingestion associated with the subsequent light period. The cosinor analysis used to estimate the feed rhythms for all tested enzymes showed that activity in the intestine and pyloric caeca exhibited significant rhythmicity (p < 0.05). However, no rhythmicity was observed in the intestinal expression of maltase-glucoamylase. Our results demonstrate that some of the behavioral and digestive physiology features of totoaba directly respond to rhythmicity in feeding, a finding that should be considered when establishing optimized feeding protocols.