NAG Activity Research Articles

Trans-cinnamic acid alleviates high-fat diet-induced renal injury via JNK/ERK/P38 MAPK pathway

Obesity-related chronic kidney disease (CKD) poses a significant risk to individuals' health and wellbeing, but the pathological mechanisms and treatment strategies are currently limited. Trans-cinnamic acid (CA) is a key active monomer found in cinnamon bark and is known for its diverse pharmacological activities. However, its effect on obesity-related renal injury remains unknown. In the current study, the in vitro and in vivo experiments were combined to investigate the beneficial effect of CA on renal injury induced by HFD or PA. We found that CA significantly reduced the obesity of zebrafish body and the accumulation of fat in kidney tissues. The histopathological changes and dysfunction induced by HFD were effectively mitigated by CA administration, as evidenced by the detection of Hematoxylin-Eosin straining, NAG activity, creatinine level, and expression of functional-related genes, respectively. Additionally, the in vitro and in vivo findings demonstrated that CA dramatically reduced the oxidative stress, inflammatory, and apoptosis in HFD-induced kidney tissues or PA-treated HEK293T and HK-2 cells. Finally, the results regarding ERK, JNK, and P38 proteins phosphorylation confirmed that CA may alleviate HFD-induced renal injury by inhibiting the phosphorylation of ERK, JNK, and P38 MAPK proteins. This theory was further supported by the results of co-treatment with anisomycin (a JNK activator) or lipopolysaccharide and CA in HEK293T cells. This study proves that CA alleviates the obesity-related CKD probably through inhibition of MAPK signaling pathway.

Lisdexamfetamine dimesylate-exposition in male rats during the peripubertal period impairs inflammatory mechanisms, antioxidant activity, and apoptosis process in kidneys of male pubertal rats.

Lisdexamfetamine dimesylate (LDX) is a prodrug of dextroamphetamine, which has been widely recommended for the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD). There are still no data in the literature relating the possible toxic effects of LDX in the kidney. Therefore, the present study aims to evaluate the effects of LDX exposure on morphological, oxidative stress, cell death and inflammation parameters in the kidneys of male pubertal Wistar rats, since the kidneys are organs related to the excretion of most drugs. For this, twenty male Wistar rats were distributed randomly into two experimental groups: LDX group-received 11,3 mg/kg/day of LDX; and Control group-received tap water. Animals were treated by gavage from postnatal day (PND) 25 to 65. At PND 66, plasma was collected to the biochemical dosage, and the kidneys were collected for determinations of the inflammatory profile, oxidative status, cell death, and for histochemical, and morphometric analyses. Our results show that there was an increase in the number of cells marked for cell death, and a reduction of proximal and distal convoluted tubules mean diameter in the group that received LDX. In addition, our results also showed an increase in MPO and NAG activity, indicating an inflammatory response. The oxidative status showed that the antioxidant system is working undisrupted and avoiding oxidative stress. Therefore, LDX-exposition in male rats during the peripubertal period causes renal changes in pubertal age involving inflammatory mechanisms, antioxidant activity and apoptosis process.

Effects of long-term no-tillage and different stover mulching amounts on soil carbon and nitrogen contents and enzyme activities of carbon and nitrogen cycle in Mollisols.

To understand the effects of different stover mulching amounts in no-tillage on soil carbon and nitrogen contents and enzyme activities, finding a stover mulching amount which can meet the requirement of soil carbon and nitrogen accumulation while maximizing economic benefits, we conducted a long-term conservation tillage field experiment since 2007 in Mollisols area of Northeast China. We analyzed soil carbon and nitrogen contents, enzyme activities and economic benefits under conventional tillage (Control, CT), no-tillage without stover mulching (NT0), no-tillage with 33% stover mulching (NT33), no-tillage with 67% stover mulching (NT67), and no-tillage with 100% stover mulching (NT100) before planting in May 2020. The results showed that compared with CT, NT0 did not affect soil organic carbon (SOC) and total nitrogen (TN) contents, but increased soil organic carbon recalcitrance and decreased the availability of dissolved organic nitrogen (DON) and ammonium nitrogen. Compared with NT0, no-tillage with stover mulching significantly increased SOC contents in 0-10 cm layer and increased with the amounts of stover. In addition, NT67 and NT100 significantly increased SOC stocks, facilitating the accumulation of soil organic matter. The effects of different stover mulching amounts on soil nitrogen content in 0-10 cm layer were different. Specifically, NT33 increased DON content and DON/TN, NT67 increased DON content, while NT100 increased TN content. Compared with CT, NT0 decreased peroxidase (POD) activity in 0-10 cm layer. Compared with NT0, NT33 increased β-glucosidase (βG), cellobiase (CB), 1,4-β-N-acetylglucosaminidase (NAG), polyphenol oxidase (PPO) and POD activities, while NT67 only increased CB, NAG and POD activities in 0-10 cm soil layer, both alleviated microbial nutrient limitation. NT100 increased PPO activity in 10-20 cm layer. NT33 increased carbon conversion efficiency of stover compared with NT100, and had the highest economic benefit. In all, no-tillage with 33% stover mulching was the optimal strategy, which could promote nutrient circulation, boost stover utilization efficiency, improve the quality of Mollisols, and maximize guaranteed income.

Effects of the Replacement of Chemical Fertilizers with Organic Fertilizers in Different Proportions on Microbial Biomass and Enzyme Activities of Soil Aggregates in Gravel-Mulched Field

Gravel-mulched fields are a unique form of drought-resistant agriculture in the northwest region of China. In recent years, continuous cropping obstacles caused by the perennial cultivation of a single crop have seriously constrained the sustainable development of sand fields. This study aimed to explore the distribution patterns of different particle sizes of aggregates (>2, 1–2, 0.25–1, and <0.25 mm) and the relationships between their microbial biomass and enzyme activities under different organic fertilization and to explore the effective measures for improving soil fertility in a gravel-mulched field with an 8-year positioning test. The results indicate that the mass percentage of soil aggregates of ≥1 mm and their mean weight diameter (MWD), microbial biomass (carbon and nitrogen, bacteria, fungi, actinomycetes, and total phospholipid fatty acids), and their related enzyme activities (leucine aminopeptidase, LAP; N-acetyl-β-d-glucosidase, NAG; β-glucosidase, BG; and polyphenol oxidase, PPO) in aggregates of different particle sizes increased with the increase in the proportion of organic fertilizers replacing the N fertilizer. Among them, the organic fertilizer replacing more than 50% of chemical nitrogen fertilizers exerted the most significant effect. With the decrease in agglomerate particle size, the contents of microbial carbon and nitrogen showed a decreasing trend, whereas LAP, NAG, and BG activities followed an increasing trend, and the change in microbial biomass was not obvious. The correlation analysis showed highly significant positive correlations between the MWD of soil aggregates, microbial biomass, and the activities of LAP, NAG, BG, and PPO. Therefore, the replacement of more than 50% of chemical fertilizer with organic fertilizer was observed to be conducive to promoting the formation of large aggregates in sandy soils and increasing the microbial biomass and enzyme activities in different sizes of aggregates.

Rice-fish coculture without phosphorus addition improves paddy soil nitrogen availability by shaping ammonia-oxidizing archaea and bacteria in subtropical regions of South China

Rice-fish coculture (RFC), as a traditional agricultural strategy in China, can optimally utilize the scarce resource, especially in subtropical regions where phosphorus (P) deficiency limits agricultural production. However, ammonia-oxidizing archaea (AOA) and bacteria (AOB) are involved in the ammonia oxidation, but it remains uncertain whether their community compositions are related to the RFC combined with and without P addition that improves soil nitrogen (N) use efficiency. Here, a microcosm experiment was conducted to assess the impacts of RFC combined with and without inorganic P (0 and 50 mg P kg−1 as KH2PO4) addition on AOA and AOB community diversities, enzyme activities and N availability. The results showed that RFC significantly increased available N content without P addition compared with P addition. Moreover, RFC significantly increased urease activity and AOA shannon diversity, and reduced NAG activity and AOB shannon diversity without P addition, respectively. Higher diversity of AOA compared with that of AOB causes greater competition for resources and energy within their habitats, thereby resulting in lower network complexity. Our findings indicated that the abundances of AOA and AOB are influenced through the introduction of fish and/or P availability, of which AOB is linked to N availability. Overall, RFC could improve paddy soil N availability without P addition in subtropical region, which provides a scientific reference for promoting the practices that reduce N fertilizer application in RFC.

Straw addition promotes the nitrification process and the wheat yield linked to trophic interactions among microbes

AbstractStraw return with nitrogen (N) fertilizer can generally regulate soil N cycling by affecting the microbial community, thereby influencing crop productivity. Bacteria and fungi play a key role in nitrification, while the effects of soil microbial interactions that include protists under the condition of straw return and N fertilizer remain uncertain. Here, we evaluated the importance of the soil microbiome, particularly protists and ammonia‐oxidizing bacteria (AOB), in regulating the soil N transformation potential and wheat yields under different fertilization practices. The results showed that the activity of β‐1,4‐N‐acetylglucosaminidase (NAG) and the potential nitrification rate (PNR) increased significantly by 156.4% ~ 312.3% and 183.1% ~ 402.6% with the addition of N fertilizer and straw, respectively. The effect on PNR was greater for straw than fertilizer addition. The fertilization practices changed the microbial community structure, and there were stronger responses from the protists and AOB. The soil microbiome formed three closely co‐occurring modules (Modules 0, 1 and 2). Among them, Module 0 showed strong positive correlations with the soil total N, NAG, PNR and crop yield and may be the key ecological cluster. Moreover, the predatory protists Cercozoa, Conosa and Ochrophyta in Module 0 were significantly positively associated with the activity of NAG and the PNR, yields and AOB. The predatory protists in Module 0 may change the soil potential nitrification rate and enhance the yield of wheat by preying on the competitors of AOB. The results suggest that the incorporation of straw promotes the N transformation potential and wheat yields linked to trophic interactions between predatory protists and AOB in fluvo‐aquic soil.

Effects of stand ages on soil enzyme activities in Chinese fir plantations and natural secondary forests.

Forest type and stand age are important biological factors affecting soil enzyme activities. However, the changes in soil enzyme activities across stand ages and underlying mechanisms under the two forest restoration strate-gies of plantations and natural secondary forests remain elusive. In this study, we investigated the variations of four soil enzyme activities including cello-biohydrolase (CBH), β-1,4-glucosidase (βG), acid phosphatase (AP) and β-1,4-N-acetylglucosaminidase (NAG), which were closely associated with soil carbon, nitrogen, and phosphorus cycling, across Cunninghamia lanceolata plantations and natural secondary forests (5, 8, 21, 27 and 40 years old). The results showed that soil enzyme activities showed different patterns across different forest types. The acti-vities of AP, βG and CBH in the C. lanceolata plantations were significantly higher than those in the natural secon-dary forests, and there was no significant difference in the NAG activity. In the plantations, AP activity showed a decreasing tendency with the increasing stand ages, with the AP activity in the 5-year-old plantations significantly higher than other stand ages by more than 62.3%. The activities of NAG and CBH decreased first and then increased, and βG enzyme activity fluctuated with the increasing stand age. In the natural secondary forests, NAG enzyme activity fluctuated with the increasing stand age, with that in the 8-year-old and 27-year-old stand ages being significantly higher than the other stand ages by more than 14.9%. βG and CBH enzyme activities increased first and then decreased, and no significant difference was observed in the AP activity. Results of the stepwise regression analyses showed that soil predictors explained more than 34% of the variation in the best-fitting models predicting soil enzyme activities in the C. lanceolata plantations and natural secondary forests. In conclusion, there would be a risk of soil fertility degradation C. lanceolata plantations with the increasing stand age, while natural secondary forests were more conducive to maintaining soil fertility.

Protective effect of naringenin on cadmium chloride-induced renal injury via alleviating oxidative stress, endoplasmic reticulum stress, and autophagy in chickens.

Cadmium (Cd) is a highly hazardous toxic substance that can cause serious harm to animals. Previous studies have indicated that cadmium chloride (CdCl2) can damage organs, such as the liver, ovaries, and testicles. Naringenin (Nar) represents a flavonoid with various properties that promote the alleviation of Cd-induced damage. In this experiment, 60 chickens were divided into the control group, 150mg/kg CdCl2 treatment group, 250mg/kg Nar treatment group, and 150mg/kg CdCl2 + 250mg/kg Nar co-treatment group, which were treated for 8weeks. Kidney tissues samples were collected to investigate kidney function, including oxidative stress (OS), endoplasmic reticulum (ER) stress, and autophagy activity. Experimental results showed the decreased weight of chickens and increased relative weight of their kidneys after CdCl2 treatment. The increase in NAG, BUN, Cr, and UA activities, as well as the increase in MDA and GSH contents, and the decrease activities of T-AOC, SOD, and CAT in the kidney, manifested renal injury by OS in the chickens. TUNEL staining revealed that CdCl2 induced apoptosis in renal cells. CdCl2 upregulates the mRNA and protein expression levels of GRP78, PERK, eIF2α, ATF4, ATF6, CHOP, and LC3, and inhibited the mRNA and protein expression levels of P62 proteins, which leads to ER stress and autophagy. The CdCl2 + Nar co-treatment group exhibited alleviated CdCl2-induced kidney injury, OS, ER stress, and autophagy. Research has demonstrated that Nar reduces CdCl2-induced kidney injury through alleviation of OS, ER stress, and autophagy.

Effects of 24 Years Different Straw Return on Soil Carbon, Nitrogen, Phosphorus, and Extracellular Enzymatic Stoichiometry in Dryland of the Loess Plateau, China

Exploring the biogeochemical cycle characteristics of soil carbon, nitrogen, and phosphorus in farmland in the dryland of the loess plateau can provide scientific basis and technical support for efficient crop production and sustainable land use. Here, based on a long-term (24 year) straw return field experiment in Shouyang, Shanxi province, the effects of different straw return regimes, i.e., straw mulching (SM), direct straw return (DS), animal-digested straw return (AS), and non-straw return (CK), on the stoichiometric ratio of soil elements and extracellular enzyme activities were studied. The vector angle and length were calculated to indicate the resource constraints faced by microorganisms. The vector angle was greater than 45° and less than 45°, indicating that microorganisms were limited by phosphorus and nitrogen, respectively. The greater the deviation from 45°, the greater the degree of limitation, and the longer the vector length, the more severely limited by carbon. The results showed that ① the soil C/N and C/P of long-term straw returning ranged from 9.81 to 14.28 and from 14.58 to 21.92, with the mean values of 12.36 and 17.51, respectively, which were 6.0% and 4.2% lower than that at the initial stage of the experiment. The soil N/P was distributed between 1.27 and 1.57, with an average of 1.42, which was 2.2% higher than that in the initial stage. The soil C/N and C/P ratios showed a trend of first decreasing and then increasing, the soil N/P ratio basically showed a flat trend, and there was no significant difference in soil element metering ratios between different straw returning treatments. ② Compared with the 24-year long-term non-straw return treatment, the activities of β-1,4-glucosidase (BG) and β-1,4-N-acetylglucosaminidase (NAG) in the soil of the long-term straw mulching treatment increased by 134.4% and 107.5% (P<0.05), the activities of BG and alkaline phosphatase (AP) in the soil of the long-term straw mulching treatment decreased by 59.3% and 59.5% (P<0.05), respectively, and the activities of NAG in the soil of the long-term straw mulching treatment increased by 102.8% (P<0.05). Under the long-term straw returning treatment, soil microorganisms were faced with carbon and phosphorus limitation as a whole. Long-term straw mulching aggravated microbial carbon limitation, and animal-digested straw return could alleviate the degree of carbon limitation. Compared with that in the 24-year long-term non-straw return treatment, soil EEAC/N could be significantly reduced by the animal-digested straw return treatment, and soil EEAC/P could be increased by the direct straw return treatment. The three straw returning methods had no significant indigenous effect on soil EEAN/P. The overall vector angle was greater than 45°, and the vector length increased by 3.8%-20.1% compared with that in the initial stage. ③ Correlation analysis showed that C and N inputs were significantly negatively correlated with BG activity; available nitrogen was significantly correlated with NAG activity, AP activity, and EEAC/N; C/P was significantly positively correlated with EEAC/N; there were significant correlations between N/P and NAG activity, AP activity, EEAC/N, and EEAC/P; and there was no significant correlation between EEAN/P and any environmental factors. In conclusion, the availability of soil nitrogen and phosphorus elements and N/P ratio had significant effects on soil extracellular enzyme activity and stoichiometric characteristics under different long-term straw returning treatments. In the future, more attention should be paid to the improvement of organic carbon and the promotion of nitrogen and phosphorus availability in farmland soil in soil-efficient cultivation and agricultural production activities.

Soil CO2 and N2O emissions and microbial abundances altered by temperature rise and nitrogen addition in active-layer soils of permafrost peatland.

Changes in soil CO2 and N2O emissions due to climate change and nitrogen input will result in increased levels of atmospheric CO2 and N2O, thereby feeding back into Earth's climate. Understanding the responses of soil carbon and nitrogen emissions mediated by microbe from permafrost peatland to temperature rising is important for modeling the regional carbon and nitrogen balance. This study conducted a laboratory incubation experiment at 15 and 20°C to observe the impact of increasing temperature on soil CO2 and N2O emissions and soil microbial abundances in permafrost peatland. An NH4NO3 solution was added to soil at a concentration of 50 mg N kg-1 to investigate the effect of nitrogen addition. The results indicated that elevated temperature, available nitrogen, and their combined effects significantly increased CO2 and N2O emissions in permafrost peatland. However, the temperature sensitivities of soil CO2 and N2O emissions were not affected by nitrogen addition. Warming significantly increased the abundances of methanogens, methanotrophs, and nirK-type denitrifiers, and the contents of soil dissolved organic carbon (DOC) and ammonia nitrogen, whereas nirS-type denitrifiers, β-1,4-glucosidase (βG), cellobiohydrolase (CBH), and acid phosphatase (AP) activities significantly decreased. Nitrogen addition significantly increased soil nirS-type denitrifiers abundances, β-1,4-N- acetylglucosaminidase (NAG) activities, and ammonia nitrogen and nitrate nitrogen contents, but significantly reduced bacterial, methanogen abundances, CBH, and AP activities. A rising temperature and nitrogen addition had synergistic effects on soil fungal and methanotroph abundances, NAG activities, and DOC and DON contents. Soil CO2 emissions showed a significantly positive correlation with soil fungal abundances, NAG activities, and ammonia nitrogen and nitrate nitrogen contents. Soil N2O emissions showed positive correlations with soil fungal, methanotroph, and nirK-type denitrifiers abundances, and DOC, ammonia nitrogen, and nitrate contents. These results demonstrate the importance of soil microbes, labile carbon, and nitrogen for regulating soil carbon and nitrogen emissions. The results of this study can assist simulating the effects of global climate change on carbon and nitrogen cycling in permafrost peatlands.

Different effects of litter and root inputs on soil enzyme activities in terrestrial ecosystems

Soil extracellular enzymes are involved in the decomposition of plant litter and soil organic matter, and their activities are of critical significance to soil carbon and nutrient turnover in terrestrial ecosystems. However, the coupling of litter and root inputs and soil enzyme activities across terrestrial ecosystems still remains not fully understood. In this study, we compiled 788 paired observations to evaluate changes in soil β-1,4-glucosidase (BG), β-d-cellobiosidase (CBH), phenol oxidase (PHO), β-1,4-N-acetyl-glucosaminidase (NAG), and acidic phosphatase (AP) activities after the removal of litter, living roots, and both litter and living roots in different ecosystems (forests, grasslands, croplands and tundra). Soil BG, NAG, and AP activities were decreased by 22.5 %, 16.6 % and 28.7 %, respectively, after removing both litter and living roots, but these effects varied in different ecosystems. Removing both litter and living roots decreased soil BG and CBH activities in forests and BG activity in croplands but increased soil CBH activity in croplands. Soil NAG activity was decreased by 15.1 % in forests but increased by 6.1 % in croplands after both litter and living roots were removed, while soil AP activity was decreased significantly across all of the studied ecosystems after both litter and living root removal. However, litter addition greatly increased soil BG, CBH, NAG and AP activities, suggesting that soil enzyme activities involved in carbon, nitrogen and phosphorus cycling were strongly controlled by plant carbon input, with an additive effect of litter and root inputs observed for C-degrading enzymes. Our synthesis also found that these enzymatic responses to plant carbon input were strongly controlled by edaphic and not climatic factors across terrestrial ecosystems. These results suggested that soil enzyme activities increased after litter addition to accelerate the decomposition of litter input but decreased after litter removal. Removing both litter and root inputs had a similar but additive effect on soil enzyme activities across sites. Although these responses varied greatly among ecosystems and litter types, edaphic factors predominantly controlled enzymatic responses over terrestrial ecosystems. Our results highlighted the importance of plant inputs in enzymatically involved carbon and nutrient cycles in terrestrial ecosystems.

Soil Enzyme Activities Affect SOC and TN in Aggregate Fractions in Sodic-Alkali Soils, Northeast of China

Soil enzymes strongly affect soil organic carbon (SOC) and nitrogen (TN) storage. However, few studies have focused on their relationships in aggregates, especially in sodic-alkali agricultural fields. In the current study, we hypothesized that the impact of soil enzymes on SOC and TN were different within aggregates for their heterogeneous distribution. Soils collected from the surface (0–20 cm) and subsurface (20–40 cm) layers of sodic-alkali agricultural fields in the northeast of China were separated via the dry sieve method into macro-aggregates (&gt;2000 μm), meso-aggregates (250–2000 μm), and micro-aggregates (&lt;250 μm). SOC, TN, microbial biomass carbon (MBC) and nitrogen (MBN), and C- and N-cycling enzymes, namely amylase (AMY), invertase (INV), β-glucosidase (GLU), catalase (CAT), β-N-acetylglucosaminidase (NAG), and urease (URE) in soil aggregates were tested and analyzed. High content of SOC and TN were observed in macro- and meso-aggregates in both layers, with the largest amount detected in meso-aggregates. The highest values of MBC and MBN were observed in meso-aggregates, followed by micro-aggregates for MBC and macro-aggregates for MBN. Soil enzymes were distributed heterogeneously in soil aggregates, where the activities of AMY, INV, and URE in both layers were in the order of meso-aggregates &gt; macro-aggregates &gt; micro-aggregates. The same trend was followed by NAG of surface soils, while in the subsurface soils, NAG activities increased with the increasing aggregate sizes. NAG activities in both layers decreased with decreasing aggregate sizes. The GLU activity rose with the decreasing aggregate sizes in both layers, contrary to CAT. Enzyme activities affect SOC and TN in soil aggregates, for NAG, INV, GLU, and URE are closely related to SOC and TN across aggregate sizes. The test indices mentioned above in the surface layer were higher than those in the subsurface layer. These results indicate that biophysical processes associated with C- and N-cycling enzymes may be vital to the SOC and TN sequestration within soil aggregates in sodic-alkali agricultural fields.

Effects of elevated CO2 concentration, warming, and winter wheat planting on soil enzyme activities.

Understanding the responses of soil enzyme activities to elevated CO2 concentration and warming can provide a scientific basis for nutrient management of croplands under global climate change. We conducted a pot expe-riment with climate chamber to examine the effects of elevated CO2 concentration and warming and winter wheat growth on soil enzyme activities. There were four climate scenarios: control (CK, 400 μmol·mol-1 CO2 concentration+normal ambient temperature), and CO2 concentration elevation (ECO2, 800 μmol·mol-1 CO2 concentration+normal ambient temperature), elevated temperature (ET, 400 μmol·mol-1 + temperature increased 4 ℃), and elevated CO2 concentration and temperature (ECO2+T, 800 μmol·mol-1 CO2 concentration + temperature increased 4 ℃). We measured the activities of soil β-glucosidase (βG), β-N-acetyl glucosidase (NAG), alkaline phosphate (ALP) and polyphenol oxidase (PPO) at four growth stages (JS, jointing stage; AS, anthesis stage; FS, filling stage and MS, maturity stage), with and without winter wheat planting. Without winter wheat planting, there was no significant difference in four kinds of soil enzyme activities between ECO2 and CK, while ET and ECO2+T treatments had significant negative effect on soil enzyme activities. With winter wheat planting, compared with CK, ECO2 and ECO2+T treatments did not affect the activities of those four soil enzyme; but the ET treatment had great impact on soil ALP and PPO activities. The activities of four kinds of soil enzyme were significantly diffe-rent between the ET and ECO2+T treatments. Compared with ET treatment, ECO2+T treatment increased soil βG activity at the JS, decreased NAG activity at the JS, increased ALP activity at both AS and FS, decreased PPO activity in the JS and increased in the AS. The interaction of elevated CO2 concentration and warming had significant effect on soil NAG and ALP activities with and without winter wheat planting. The interaction of warming and expe-rimental stage had significant effect on four kinds of soil enzyme activities without winter wheat planting, but the interaction of warming and crop growth stage had significant effect on ALP and PPO activities with winter wheat planting. The interaction of elevated CO2 concentration, warming and experimental period had significant effect on soil βG, ALP and PPO activities without winter wheat growth, while with winter wheat growth, it had significant impact on NAG, ALP and PPO activities. The winter wheat growth had significantly inhibitory effect on βG, NAG and ALP activities in the two early growth periods (JS+AS), significant promoting effect in the later growth periods (FS+MS), and significantly inhibitory effect on PPO activity during whole growth period. Overall, elevated CO2 concentration did not affect soil enzyme activities, while the elevation of CO2 concentration and temperature on soil enzyme activities differed among the soil enzymes at different growth stages. In addition, the responses of four soil enzyme activities to the interaction of elevated CO2 concentration and warming varied with and without winter wheat planting.

Intercropping-driven nitrogen trade-off enhances maize productivity in a long-term experiment

Intercropping improves land productivity by exploiting species complementarities to achieve sustainable agriculture. Intercropping systems, therefore, require a nitrogen (N) management approach that matches temporal and spatial N supply with crop requirements. Present field-based study (started in 2013) explored the effects of intercropping of maize ( Zea mays L. ) with legumes [peanut ( Arachis hypogaea ) and soybean ( Glycine max )] and non-legumes [gingelly ( Sesamum indicum L. ) and sweet potato ( Dioscorea esculenta )] on maize productivity and N trade-off. Compared with maize monoculture, intercropping with gingelly, peanut, soybean, and sweet potato all significantly improved maize average yield (2013 and 2021), average N use efficiency (NUE), average N partial factor productivity (PFPN), and plant N uptake by 8–29%, 28–49%, 20–80%, and 16–35%, respectively. The N losses via ammonia volatilization and runoff in intercropping systems decreased by 12–19% and 11–43% respectively, compared with monoculture. Soil total N, inorganic N (NH 4 + -N and NO 3 - -N), and microbial biomass N (MBN) contents as well as the urease, β-1,4-N-acetyl-glucosaminidase (NAG), and leucine aminopeptidase (LAP) activities varied among different intercropping systems and maize growth periods. Maize productivity (yield, PFPN, and NUE) was positively correlated with plant N uptake (R 2 = 0.66–0.92, P < 0.001) and soil MBN content (R 2 = 0.41–0.47, P < 0.01), while it was found negatively associated with N losses (R 2 = 0.35–0.56, P < 0.05), soil N availability (R 2 = 0.27–0.67, P < 0.05), and NAG activity (R 2 = 0.36–0.55, P < 0.05). These findings collectively indicated that regulating the balance between soil N supply and plant N uptake in an intercropping system with low N fertilization could achieve high productivity. This study highlighted the importance of understanding the complex interaction between crop development and intercropping practices in improving maize productivity and N trade-off. • Intercropping increased average (2013 and 2021) maize yield by 8–29%. • Intercropping improved average NUE by 28–49% and maize N uptake by 16–35%. • N loss via ammonia volatilization and runoff decreased by 11–43% duo to intercropping. • Maize productivity was primarily related to plant N uptake, soil N dynamics and N loss. • Intercropping-driven plant-soil N trade-offs contributed to increased maize productivity.

Microplastics in soil can increase nutrient uptake by wheat

Microplastics can perturb microbial nutrient-mining strategies. However, the mechanism by which microplastics affect the resource-acquisition strategies of crops in agricultural systems remains unknown. The nutrient-acquisition potential of crops and microbes was investigated under treatments with two common microplastics (polyethylene [PE] and polyvinyl chloride [PVC]) at 0%, 1%, and 5% (w/w). Different root resource-acquisition strategies disturbed microbial nutrient turnover in the rhizosphere in response to microplastic addition. Specifically, the β-1,4-glucosidase (BG) hotspot expanded, whereas the rhizosphere expansion of BG activity decreased. A decrease of less than PE1% (w/w) and an expansion of less than PE5% (w/w) in the 1,4-N-acetyl-glucosaminidase (NAG) hotspot with wider rhizosphere expansion of NAG activity indicated that higher doses of PE allow roots to uptake additional N. The phosphomonoesterase (PHOS) hotspot decreased in PE1% (w/w) and expanded in PE5% (w/w), but rhizosphere expansion did not change under PE treatments. However, both NAG and PHOS hotspots expanded with decreasing rhizosphere expansion under PVC treatments, indicating that PVC limits the utilization of available N and P, forcing the crop to obtain nutrients from the narrow root zone. These results indicate that adding PE microplastics increases the demand for and consumption of NH4+-N and NO3--N by wheat.

Distinction of Degrees of Ischemic Kidney Parenchymal Injury in Children with Congenital Vesicoureteral Reflux (According to Enzymological Criteria)

The objective: to evaluate the possibility of determining the levels of activity of N-acetyl-β-D-glucosaminidase B (NAG B) in urine as an enzymological marker of differentiation of ischemic damage to the renal parenchyma in children with congenital vesicoureteral reflux (VUR). Materials and methods. 49 children aged 1 to 15 years with a verified diagnosis of unilateral VUR and 25 practically healthy children were examined. NAG B activity in urine was determined before reconstructive treatment. The limits of the reference intervals of the levels of enzyme activity in the urine of healthy children were calculated by the formula M±1.5σ. According to the personalized analysis the patientswere divided into 3 groups: group 1 – 13 patients (the levels of NAG activity in the urine are registered from 0.8 to 2.3 units); group 2 – 14 patients (the levels of NAG activity in the urine – 2.4 to 4.5 units); group 3 – 22 patients (the levels of NAG activity in urine – 4.6 to 10.5 units. Results. In the urine of healthy children, the activity of NAG B averages 1.56±0.096 units, σ=0.48, reference levels are recorded from 0.8 to 2.3 units. In the urine of the 1st group, the levels of NAG B activity are equal to 1.61±0.13 units correspond to the control values and are evaluated as zero degree of ischemic damage of a renal parenchyma; in the urine of the 2nd group – 3.97±0.17 units exceed the average control values by 1.6–2.9 times and are assessed as moderate or I degree of ischemic damage to the renal parenchyma; in the urine of the 3rd group – 7.50±0.39 units exceed the average control values by 3 times or more and are assessed as severe or II degree of ischemic damage to the renal parenchyma (p2,3-1&lt;0,001; p3-2&lt;0.001). Conclusions. The expediency of determining the activity levels of N-acetyl-β-D-glucosaminidase B in the urine of children with congenital vesicoureteral reflux, as an enzyme with pronounced renospecific properties and as enzyme marker for differentiating the degrees of ischemic damage (0, I, II) of the renal parenchyma was established. Activity levels of NAG B can be used as well for timely prevention of the development and progression severe complications through the timely appointment of the appropriate optimal corrective therapy.

Carbon, Nitrogen, Phosphorus, and Extracellular Soil Enzyme Responses to Different Land Use

Extracellular soil enzymes play a key role in soil organic matter decomposition and nutrient cycling. However, it is not fully understood how these enzymes respond to different land use. Long-term research studies were used to evaluate how diversified management practices affect extracellular enzymes driving C cycling [phenol oxidases (PO), peroxidases (PP), α-glucosidase (AG), β-glucosidase (BG), cellobiohydrolase (CB), β-1,-4-Nacetylglucosaminidase (NAG)], N cycling [leucine aminopeptidase (LAP)], and P cycling [phosphomonoesterase (PME)]. The soil pH, contents of total organic C, total N, mehlich-3 P, soil respiration and soil nitrogen supply capacity were also measured. Different land use included tillage frequency, tillage regimes, mineral N fertilization, crop rotations and liquid dairy manure. Compared to medium or high tillage frequency, low tillage frequency increased total organic C and total N and soil respiration as well as NAG and PME activities, whereas it decreased soil nitrogen supply, mehlich-3 P, and soil pH, as well as PO, PP, AG, BG, CB, and LAP activities. Non till was associated with lower PP and PO activities than moldboard plow. Nitrogen fertilization decreased soil pH and PO activity but increased PME activity. Barley (Hordeum vulgare) in rotation with forage increased total organic C, total N, soil nitrogen supply and soil respiration by 31, 21, 44, and 33%, respectively, in comparison with barley in monoculture. The application of liquid dairy manure increased soil pH, total N and soil nitrogen supply and soil enzyme activities (AG, BG, NAG) in comparison to the mineral N fertilizer. When principal component analysis was performed, soil pH, PO, PP, CB, LAP, and PME were grouped in the first component, which explained the highest variance. This is the core group controlling the C, N, and P cycling. The activities of C, N, and P acquiring enzymes, soil nitrogen supply and soil respiration were related to changes in soil total C and N, and extractable P contents across a broad range of management practices. Increased PO and PP activities reflect total C decline.

Maize root exudate composition alters rhizosphere bacterial community to control hotspots of hydrolase activity in response to nitrogen supply

Improving nitrogen (N) acquisition by crops from soil is essential to reduce fertilization rates whilst maintaining yields. Plants can adapt their nutrient acquisition strategies according to N availability, which also affects soil microbial community structure, functions and activities and relies on the supply of carbon (C) for energy. We hypothesized that N deprivation would create hotspots of N- and C-acquiring hydrolase activities in maize rhizosphere through the effects of altered root exudation on the rhizosphere bacterial community. We grew maize under three N fertilization rates and combined soil zymography with the identification of rhizosphere microbial communities and non-targeted metabolic profiling of root exudates to explore enzyme hotspot formation. The rhizosphere extents of β-1,4-glucosidase (BG) and β-N-acetylglucosaminidase (NAG) activities decreased after N fertilization, narrowing by 48% and 39%, respectively, under typical field N application rates compared to zero application. Rhizosphere extents of enzyme activities were more sensitive to altered N supply than changes in the rates of enzyme activities: BG activity decreased by ∼10%, while NAG activity was unaffected. Decreases in the activities of both hydrolases and their rhizosphere extents caused by N addition correlated with reduced abundances of oligotrophs. The relative abundances of oligotrophic bacteria (e.g., Acidobacteria) decreased, while copiotrophs (e.g., Pseudomonadota and Patescibacteria) increased under the highest N application rate. Co-occurrence networks of the rhizosphere bacterial community revealed that functional units increased with BG activity, while an efficient and denser co-occurrence network supported expansion of its rhizosphere extent. The metabolic profiles of root exudates changed according to the N application rate, suggesting that their chemistry was regulated by the plant in response to N supply. The composition of root exudates and dissolved organic C and nitrate contents explained the largest variations in NAG hotspots in the rhizosphere. In summary, maize actively adjusts the composition of root exudates to increase interactions with rhizosphere bacteria, thereby stimulating hydrolase production and activities, and altering their rhizosphere extents to mobilize N and energy (C) in a larger soil volume, under conditions of N deficiency.

Switchgrass cropping systems affect soil carbon and nitrogen and microbial diversity and activity on marginal lands

AbstractSwitchgrass (Panicum virgatum L.), as a dedicated bioenergy crop, can provide cellulosic feedstock for biofuel production while improving or maintaining soil quality. However, comprehensive evaluations of how switchgrass cultivation and nitrogen (N) management impact soil and plant parameters remain incomplete. We conducted field trials in three years (2016–2018) at six locations in the North Central Great Lakes Region to evaluate the effects of cropping systems (switchgrass, restored prairie, undisturbed control) and N rates (0, 56 kg N ha−1 year−1) on biomass yield and soil physicochemical, microbial, and enzymatic parameters. Switchgrass cropping system yielded an aboveground biomass 2.9–3.3 times higher than the other two systems (Jayawardena et al., unpublished data) but our study found that this biomass accumulation did not reduce soil dissolved organic C, total dissolved N (TDN), or bacterial diversity. The annual aboveground biomass removal for bioenergy feedstock, however, reduced soil microbial biomass C (MBC) and microbial biomass N (MBN) and bacterial richness in the second and third years; despite this, continuous monocropping of switchgrass improved soil TDN, inorganic N, bacterial diversity, and shoot biomass in the second and/or third years compared with the first year. N fertilization increased aboveground biomass yield by 1.2 times and significantly increased soil TDN, MBN, and the shoot biomass of switchgrass compared with the unfertilized control. Locations with higher C and N contents and lower C:N ratio had higher aboveground biomass, MBC, MBN, and the activity of BG, CBH, and UREA enzymes; by contrast, locations with higher pH had higher soil TDN and activity of NAG and LAP enzymes. Our research demonstrates that switchgrass cultivation could improve or maintain soil N content and N fertilization can increase plant biomass yield. The comprehensive data also can inform future biogeochemical models to successfully implement switchgrass for bioenergy production.

Changes in rhizosphere-specific enzyme activity during secondary grassland succession in the Loess Plateau, China

ABSTRACT Dynamics of soil enzyme activity during plant restoration processes have been studied extensively; however, a general understanding of the rhizosphere-specific enzyme activity during plant secondary succession is limited. Rhizosphere samples were collected from the dominant and main companion species in farmlands abandoned for up to 32 years in the Loess Plateau. We determined soil chemical properties, phospholipid fatty acid (PLFA) profiles and activities of four enzymes (β-1,4-glucosidase, BG; β-1,4-N-acetylglucosaminidase, NAG; L-leucine aminopeptidase, LAP and alkaline phosphatase, AP), specific enzyme activity per soil organic carbon (SOC) and per PLFA unit. Specific BG, NAG, LAP and AP activities per SOC unit significantly decreased 77.1%, 53.2%, 83.0% and 49.2% with plant succession. Specific BG, NAG and LAP activities per PLFA unit significantly decreased 59.6%, 18.9% and 70.9% with plant succession. Furthermore, specific BG and LAP activities in the dominant species were lower than those in the companion species. Redundancy analysis revealed that variations in specific enzyme activities per SOC and per PLFA unit were explained 76.6% and 68.6% by soil chemical properties. SOC, total nitrogen (TN) and available phosphorus (aP) significantly influenced the rhizosphere-specific enzyme activities. This study improved the understanding of the element cycle at the root–soil interface under secondary succession ecosystems.