Mn Treatment Research Articles

Study of excess manganese stress response highlights the central role of manganese exporter Mnx for holding manganese homeostasis in the cyanobacterium Synechocystis sp. PCC 6803.

Cellular levels of the essential micronutrient manganese (Mn) need to be carefully balanced within narrow borders. In cyanobacteria, a sufficient Mn supply is critical for ensuring the function of the oxygen-evolving complex as the central part of the photosynthetic machinery. However, Mn accumulation is fatal for the cells. The reason for the observed cytotoxicity is unclear. To understand the causality behind Mn toxicity in cyanobacteria, we investigated the impact of excess Mn on physiology and global gene expression in the model organism Synechocystis sp. PCC 6803. We compared the response of the WT and the knock-out mutant in the Mn exporter (Mnx), ∆mnx, which is disabled in the export of surplus Mn and thus functions as a model for toxic Mn overaccumulation. While growth and pigment accumulation in ∆mnx were severely impaired 24 h after the addition of tenfold Mn, the WT was not affected and thus mounted an adequate transcriptional response. RNA-seq data analysis revealed that the Mn stress transcriptomes partly resembled an iron limitation transcriptome. However, the expression of iron limitation signature genes isiABDC was not affected by the Mn treatment, indicating that Mn excess is not accompanied by iron limitation in Synechocystis. We suggest that the ferric uptake regulator, Fur, gets partially mismetallated under Mn excess conditions and thus interferes with an iron-dependent transcriptional response. To encounter mismetallation and other Mn-dependent problems on a protein level, the cells invest in transcripts of ribosomes, proteases and chaperones. In the case of the ∆mnx mutant, the consequences of the disability to export excess Mn from the cytosol manifest in additionally impaired energy metabolism and oxidative stress transcriptomes with a fatal outcome. This study emphasizes the central importance of Mn homeostasis and the transporter Mnx's role in restoring and holding it.

Exogenous N Supply on N Transportation and Reuse during the Rice Grain-Filling Stage and Its Relationship with Leaf Color-Changing Parameters

During the later reproductive period of rice growth, the chlorophyll in the leaves degraded, accompanied by the nitrogen (N) transportation from leaves to panicle, resulting in a change in leaf color from green to yellow. This study aimed to investigate the effects of exogenous N supply on leaf color-changing, N accumulation, N transportation, and N loss of indica-japonica hybrid rice during the grain-filling stage. Two indica-japonica hybrid rice cultivars, Chunyou 167 (CY167) and Chunyou 927 (CY927), which exhibited significant differences in leaf color-changing during the grain-filling stage, were selected as materials for field experiment and hydroponic experiment with low, medium, and high N treatments (LN, MN, and HN). The dynamic changes in SPAD value from heading to maturity were measured and fitted with quadratic function to extract leaf color-changing parameters; labeled 15N was used as N source after heading to trace the source of N in the panicle and the remobilization of vegetative organ N. The results showed that 67.37–72.38% of the panicle N was transported from vegetative organs, the N transport efficiency was the upper three leaves > lower leaves > stem, and about 3.1–35.0% of the transported N was lost via volatilization. The effects of exogenous N concentration on N harvest index, N dry matter/grain production efficiency, N reuse efficiency, and N loss were closely related to leaf color-changing parameters. In MN and HN treatment, the N loss was negatively correlated with the onset time of leaf color-changing (T0) and the final leaf color index (CIf), but positively correlated with the leaf color-changing rate (Rmean). Increasing the supply of exogenous N increased T0 and CIf, but decreased Rmean, N transport/reuse efficiency, N harvest index, and N dry matter/grain production efficiency. Compared to the cultivar CY167 with normal leaf color-changing, the “stay-green” cultivar CY927 had higher T0, CIf, and lower Rmean, resulting in less N volatilization loss, lower N harvest index and N transport efficiency, while higher N reuse efficiency. In conclusion, the exogenous N supply affects leaf color by influencing the transportation and reuse of leaf N during the grain-filling stage.

The operating performance of Modified Basalt Fibers (MBF) bio-nest reactor exposed to nano-plastics

Biological nests made of Modified Basalt Fiber (MBF bio-nests) serve as effective carriers for enhancing wastewater treatment. However, little is known about their performance when exposed to nano-plastics. This study investigates the decontamination efficiency and microbial functionality of four types of MBF and traditional Basalt Fibers (BF) as carriers in contact oxidation reactors. Compared to BF, MBF demonstrated superior growth effects and biocompatibility within the bio-nest. Ca-MBF and Mn-MBF bio-nests exhibited the highest and most uniform absorption capacities, respectively, alongside increased secretion of total Extracellular Polymeric Substances (EPS) and higher Protein to Sugar (PN/PS) ratios. In sewage environments, all MBF groups displayed stable performance in removing NH4+-N and COD. Significant removal of TN and TP was notably observed in Mn-MBF treatments. Mn and Ca treatments predominantly influenced the Proteobacteria and Bacteroidetes phyla, crucial for nitrogen and phosphorus removal. Following exposure to nano-plastics, Mn-MBF and Ca-MBF treatments maintained high decontamination efficiency, particularly for TP and COD (48.64 % to 57.78 % and 90.91 % to 92.89 %, respectively). The significant removal of NH4+-N and TP only occurred in Mn-MBF and Ca-MBF treatments, which stimulated the growth of bacteria resistant to nano-plastics. Key genera such as Zoogloea and Meganema were identified as dominant, contributing to organic matter decomposition, EPS secretion, biofilm condensation, and enhanced microbial attachment. The findings underscore the structural stability enhancement of Mn-MBF and Ca-MBF bio-nests in contact oxidation reactors, demonstrating their resilience against nano-plastic pollution.

Effects of short-term nitrogen addition on the recovery of alpine grassland in the Tianshan Mountains of Xinjiang, China.

The restoration of alpine grasslands has garnered significant attention across various sectors. Historically, natural restoration has been the primary approach for grassland recovery, characterized by its prolonged duration. To expedite the recovery of degraded grasslands, it is essential to identify the limiting factors of restoration, enabling efficient and rapid recovery. Appropriate nitrogen (N) addition levels have been considered a potential strategy to enhance the recovery of grassland ecosystems and augment their ecological benefits. However, the effectiveness of N addition in alpine grassland restoration remains debated. This study investigated the impact of five N addition levels (CK: control [0 g/m2]; LN: low N [5 g/m2]; MN: medium N [10 g/m2]; HN: high N [15 g/m2]; SN: severe N [20 g/m2]) and two experimental approaches (N addition once per year [NPY] and three times per year [NTY] at the same dosages) on plant and soil properties and the maximum restoration capacity of alpine meadows. Our findings reveal three key insights: The level of N addition was the primary factor influencing aboveground plant biomass and coverage. Plant diversity decreased under the NTY regime and increased with NPY in the Bayinbruck grassland. N addition significantly altered soil properties, including pH, salinity, soil organic carbon (SOC), soil-available phosphorus (AP), and soil total phosphorus (TP). Notably, soil TP, total nitrogen (TN), and AP substantially impacted plant community structure and diversity. Based on structural equation model (SEM) and analysis of variance (ANOVA), optimal grassland restoration was achieved with the HN (15 g/m2) treatment under NPY and the MN and HN (10 and 15 g/m2) treatments under NTY. Overall, our study offers crucial insights into the conservation, management, and restoration of grassland ecosystems on the Bayinbruck Plateau. It underscores the significance of N addition effects on plant communities, vegetation restoration, and soil properties.

Effects of Nitrogen Forms on Soil Enzyme Activities in a Saline-Alkaline Grassland.

Global climate change and agricultural practices have increased atmospheric nitrogen (N) deposition, significantly affecting the nitrogen cycling process in grasslands. The impact of different N forms on key soil enzyme activities involved in N nitrification, particularly in the saline-alkali grasslands of the Hexi Corridor, using natural grassland as a control (CK) and adding three N treatments: inorganic N (IN), organic N (ON) and a mixed N treatment (MN, with a 4:6 ratio of organic to inorganic N). Our study assessed the effects of these N forms on soil properties and enzyme activities crucial for N cycling. The findings indicate that different N forms significantly enhance soil mineral N content, with ON treatment leading to the highest increases in nitrate and ammonium content 92.44% and 35.6%, respectively, compared to CK. Both IN and ON treatments significantly boosted soil nitrate reductase and urease activities (p < 0.05), while MN treatment decreased nitrate reductase activity, with ON treatment showing the greatest sensitivity to enzyme activity changes. Soil pH slightly increased with N addition, but soil nitrite reductase activity remained relatively unchanged (0.372-0.385 mg g-1). Correlation analysis revealed that soil mineral N content and pH are key regulators of enzyme activities in saline-alkaline grasslands. These results suggest that different N forms should be considered in nutrient cycling models, with organic N addition potentially enhancing soil N conversion and mitigating nutrient limitations in grassland ecosystems.

391 The impact of trace mineral source on systemic immunological status associated with early embryonic loss in lactating dairy cattle

Abstract Milk production has doubled from 1970 to 2009 but has been associated with a decline in fertility. Around 25% of failed pregnancies in dairy cattle are due to embryonic loss. Mineral bioavailability may affect embryonic retention, so we hypothesized that Zn, Cu, and Mn sources will influence systemic immunological status, which affects early embryonic retention. Holstein cows (n = 58) were randomly assigned to one of two daily oral drench trace mineral (Zn, Cu, and Mn) treatments 30 d before breeding (d -30): 1) Inorganic (ITM) or 2) Metal Methionine Hydroxy Analog Chelate (MMHAC). Before treatments began, cows were assigned to a semen type, beef vs. Holstein, equally, across treatments. All cows underwent a double Ovsynch protocol and were artificially inseminated on d 0. Humoral immunological status was assessed in serum samples taken on d 0 and d 7. Immune activity was quantified via a D2Dx systemic immunity score, which assesses samples for the presence of IgG, IgM, cytokines, and complement proteins. Ultrasonography was utilized for pregnancy confirmation on d 35, classifying cows as pregnant (P) or open. Progesterone analysis from d 21 plasma was used to categorize open cows as either non-pregnant (NP) or early embryonic loss (EEL). Statistical analyses in R Studio were completed, in two models based on pregnancy (P vs EEL and NP vs EEL), to determine the effects of mineral treatment, pregnancy status, semen type, and all interactions on humoral immune status. In the P vs EEL model, there were no effects (P &amp;gt; 0.30) of semen type, mineral treatment, pregnancy status, or any interactions on systemic immunity score on the day of breeding (d 0) or d 7. On d 0, cows provided MMHAC had a systemic immunity score of 0.073 ± 0.008 but were not different (P &amp;gt; 0.34) from ITM cows (0.063 ± 0.006). This trend continued on d 7 with systemic immunity scores of MMHAC cows not differing (P &amp;gt; 0.32) from ITM cows (0.055 ± 0.004 and 0.061 ± 0.003; respectively). There was a tendency (P = 0.10) for the three-way interaction of semen type x pregnancy x treatment to influence the immunity score change from d 0 to d 7. Pregnant cows on ITM treatment bred with beef semen had a positive change in immunity score (0.020 ± 0.0085). Whereas ITM cows bred with Holstein semen that underwent EEL had a negative change (-0.015 ± 0.0085); all other means were intermediate. In the NP vs EEL model, there were no effects (P &amp;gt; 0.14) of semen type, treatment, pregnancy status, or any interactions on systemic immunity score on d 0, d 7, or the change between d 0 and d 7. In summary, trace mineral bioavailability tended to affect systemic immunological status in P vs EEL cows but not in NP vs EEL cows, which may allow for the elucidation of immunological status differences during pregnancy establishment.

Manganese enhances cadmium tolerance in barley through mediating chloroplast integrity, antioxidant system, and HvNRAMP expression

Cadmium (Cd) is a toxic heavy metal that poses risks to crop production and food safety worldwide. This study evaluated whether manganese (Mn) addition could mitigate Cd toxicity and reduce Cd accumulation in barley seedlings. Hydroponically grown seedlings of Cd-tolerant (WSBZ) and Cd-sensitive (Dong17) barley cultivars were treated with 0.1 μM and 1 μM Cd as well as 0.2 mM Mn alone and in a combination with 0.1 or 1.0 μM Cd for 21 days. Cd exposure caused the dramatic alteration of growth and physiological parameters by disrupting chloroplast, and increased Cd accumulation in both genotypes. However, Mn addition markedly alleviated the negative impacts of all examined parameters caused by Cd stress. Cd addition enhanced expression of anti-oxidative enzyme related genes, including HvSOD, HvCAT, HvAPX, HvPOD in the two barley genotypes exposed to Cd stress. The expression analysis showed nearly all HvNRAMPs genes are dramatically up regulated by both Mn and Cd, with WSBZ having higher expression than Dong 17. Notably, HvNRAMP1 showed the highest expression due to Mn addition, highlighting its crucial role in Mn uptake and transportation in barley. Moreover, Cd stress and Mn addition increased and suppressed the expression of HvYSL5, HvHMA2 and HvHMA3, respectively. Conversely, the expression of HvYSL2, HvIRT1 and HvMTP8 was upregulated by both Mn and Cd treatments, with a further increase observed in the combined Cd and Mn treatments. It may be concluded that sufficient Mn supply is quite important for reducing Cd uptake and accumulation in plants.

The Crop Phosphorus Uptake, Use Efficiency, and Budget under Long-Term Manure and Fertilizer Application in a Rice–Wheat Planting System

Little is known about the effect of the long-term application of organic and inorganic fertilizers on P-use efficiency, P budget, and the residual effect of P fertilizer. To clarify the effect of different fertilization on soil P balance in a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) rotation system is helpful to promote the sustainable development of agriculture. Thus, a thirty-five-year fertilizer experiment was conducted with eight treatments, including an unfertilized control (CK); chemical nitrogen (N), phosphorus (P), and potassium (K) fertilizers; and organic manure (M) either alone or in combination treatments (N, NP, NPK, M, MN, MNP, and MNPK). The results indicated that crop yields and P uptake were higher in the combined application of manure and chemical fertilizer treatments than in the manure or chemical fertilizer alone treatments. Soil P budget indicated a 23.4–55.4 kg P ha−1 yr−1 surplus in the organic combined with or without mineral fertilizer treatments, but the soil P budget indicated a 20.0 and 21.9 kg P ha−1 yr−1 deficit in the control and N treatments. The proportion of residual fertilizer P converted to soil available P in NP, NPK, M, MN, MNP, and MNPK treatments was 4.5%, 4.8%, 19.1%, 19.0%, 11.5%, and 13.3%, respectively, over a 35-year period. Furthermore, according to the higher P content and crop uptake in organic manure treatment compared with chemical P fertilizer alone, an organic addition could effectively reduce the use of chemical fertilizer and become an effective way of sustainable development in practice. Therefore, the combined application of organic and inorganic fertilizer will be a practical method to increase crop yields and soil P status in a rice–wheat planting system.

Phosphorus-induced restructuring of the ascorbate-glutathione cycle and lignin biosynthesis alleviates manganese toxicity in peach roots.

Manganese (Mn) is indispensable for plant growth, but its excessive uptake in acidic soils leads to toxicity, hampering food safety. Phosphorus (P) application is known to mitigate Mn toxicity, yet the underlying molecular mechanism remains elusive. Here, we conducted physiological and transcriptomic analyses of peach roots response to P supply under Mn toxicity. Manganese treatment disrupted root architecture and caused ultrastructural damage due to oxidative injury. Notably, P application ameliorated the detrimental effects and improved the damaged roots by preventing the shrinkage of cortical cells, epidermis and endodermis, as well as reducing the accumulation of reactive oxygen species (ROS). Transcriptomic analysis revealed the differentially expressed genes enriched in phenylpropanoid biosynthesis, cysteine, methionine and glutathione metabolism under Mn and P treatments. Phosphorus application upregulated the transcripts and activities of core enzymes crucial for lignin biosynthesis, enhancing cell wall integrity. Furthermore, P treatment activated ascorbate-glutathione cycle, augmenting ROS detoxification. Additionally, under Mn toxicity, P application downregulated Mn uptake transporter while enhancing vacuolar sequestration transporter transcripts, reducing Mn uptake and facilitating vacuolar storage. Collectively, P application prevents Mn accumulation in roots by modulating Mn transporters, bolstering lignin biosynthesis and attenuating oxidative stress, thereby improving root growth under Mn toxicity. Our findings provide novel insights into the mechanism of P-mediated alleviation of Mn stress and strategies for managing metal toxicity in peach orchards.

Geochemical drivers of manganese removal in drinking water reservoirs under hypolimnetic oxygenation

Manganese (Mn) is a naturally occurring contaminant commonly found in drinking water supplies. In lakes and reservoirs, water authorities increasingly use in situ treatment by hypolimnetic oxygenation (HOx) systems to remove metals such as Mn from the water column. HOx systems introduce dissolved oxygen (DO) to the bottom waters (hypolimnion) to promote oxidation and subsequent removal of metals from the water column. Previous laboratory studies have shown the importance of individual geochemical drivers (pH, alkalinity, mineral surfaces) on Mn oxidation, but few studies have examined the influence of these drivers of Mn removal in concert. In this study, we conducted field monitoring and laboratory experiments to examine how pH, alkalinity and the presence of mineral particles influence Mn removal at two drinking water reservoirs in southwest Virginia, both with HOx systems: Falling Creek Reservoir (FCR) and Carvins Cove Reservoir (CCR). Both reservoirs have had historical issues with elevated (>0.05 mg/L) Mn concentrations during seasonal stratification (May–October). Watershed geology contributes to differences in pH and alkalinity between the reservoirs, with FCR having lower historical medians of hypolimnetic pH and alkalinity (6.6 and 18 mg/L CaCO3, respectively) than CCR (7.2 and 62 mg/L CaCO3, respectively).Results of laboratory experiments examining the influence of pH on Mn removal showed substantial Mn loss within 14 days only under high pH (10) conditions. Mn removal did not occur at pH 6 or 8 over the same 14-day period. In experiments with pH 10 and alkalinity >70 mg/L CaCO3, near-total Mn removal occurred within 2 h. Mn removal occurred concurrently with precipitation of microscopic (<5 μm) particles, followed by formation of macroscopic (>100 μm) particles. Particles of both size classes were identified as Mn oxides (MnOx). These observations suggest that increasing pH and alkalinity promotes Mn oxidation and subsequent removal from solution. Results of experiments with pH 10 and alkalinity >70 mg/L CaCO3 suggest that heterogeneous oxidation by MnOx partially drives rapid Mn removal. Thus, initial formation of MnOx creates a positive feedback loop that can enhance additional Mn loss. In experiments using water collected from FCR and CCR, we observed rapid Mn removal in unfiltered water (0.002–0.05 d−1) but no significant removal of Mn in filtered water. These results, in combination with results of analysis of particles collected from reservoir water, suggest that minerals present in the water column likely catalyze MnOx formation. Together, our experimental results suggest that heterogenous oxidation is an important process of Mn removal, while pH and alkalinity variations of the range expected in natural freshwaters contribute less to differential Mn removal. The formation of MnOx particles during in situ oxygenation, as well as the presence of suspended minerals that occur naturally in water columns, play an important role in promoting Mn oxidation and should be accounted for in Mn removal treatment strategies.

The role of circHmbox1(3,4) in ferroptosis-mediated cognitive impairments induced by manganese

Excessive environmental exposure to manganese (Mn) has been linked to cognitive impairments, circular RNAs (circRNAs) have been recognized for their roles in epigenetic regulation in various biological processes, including neurological pathogenesis. Previous studies found that ferroptosis, an iron ion-dependent programmed cell death, may be involved in cognitive impairments. However, specific mechanisms underlying the relationship among circRNA, ferroptosis, and neurotoxicity of Mn are not well-understood. In the current study, RNA sequencing was performed to profile RNA expression in Neuro-2a (N2a) cells that were treated with 300 μM Mn. The potential molecular mechanisms of circHmbox1(3,4) in Mn-induced cognitive impairments were investigated via various experiments, such as Western blot and intracerebroventricular injection in mice. We observed a significant decrease in the expression of circHmbox1(3,4) both in vitro and in vivo following Mn treatment. The results of Y maze test and Morris water maze test demonstrated an improvement in learning and memory abilities following circHmbox1(3,4) overexpression in Mn treated mice. Mn treatment may reduce circHmbox1(3,4) biogenesis through lowered expression of E2F1/QKI. Inhibiting circHmbox1(3,4) expression led to GPX4 protein degradation through protein ligation and ubiquitination. Overall, the current study showed that Mn exposure-induced cognitive dysfunction may be mediated through ferroptosis regulated by circHmbox1(3,4).

Assessing The Toxicity Of Heavy Metals And Potential Tolerance Of Common Bean (Phaseolus vulgaris) While Monitoring The Population Dynamics Of The Associated Rhizobia

Microbially-assisted phytoremediation (MAP) is increasingly recognized as the feasible alternative for removing hazardous heavy metals (HMs) from contaminated environments. However, the dynamics of rhizobial-plant interactions during phytoremediation remain unclear. This study investigated the toxicity of some selected heavy metals (Cobalt, Nickel, and Manganese), the potential tolerance of Phaseolus vulgaris grown in the HMs-rich effluents, and the population dynamics of the associated Rhizobia within the Katsina metropolis. After 80 samples of P. vulgaris collected from Lambun Sarki garden were exposed to 10 mL of 0.5-2g/L of Ni and Co and 5-20 g/L Mn, respectively, in mesocosms, and the plants treated with 10 mL HMs solutions daily, for three weeks. Indices of HMs toxicity on seeds and plants (4 and 3, respectively) were monitored in all treatments. Weekly rhizobial counts on Congo Red Yeast Extract Mannitol Agar (CRYEMA) were taken to monitor rhizobial population dynamics. Pure isolates obtained after three iterations were identified biochemically. One-way ANOVA was employed for statistical analyses using AnalyStat (version 1.6.50). Generally, Ni exerts the highest toxicity, with Mn having less toxicity. Average rhizobial counts increased weekly, with high counts obtained in Ni and Mn treatments. However, they did not differ significantly between weeks (p = 0.061). Thus, longer time intervals (&gt;2 weeks) are required to observe significant shifts in population dynamics. Moreover, HMs concentration did not affect the colony counts (p = 1.00). Metabolism profile of the preliminarily identified Rhizobium sp. and Sinorrhizobium melliloti evidenced HMs removal and plant growth promotion ability. The research demonstrated the phytoremediation ability of P. vulgaris and how rhizospheric population dynamics change during phytoremediation and contributed towards understanding HMs impact as environmental stressors on rhizospheric plant-microbe interactions. Future research targeting the hyperaccumulation capacity of the plants and heavy metals tolerance of the identified rhizobia are recommended, as this may help in knowing the BCF, TF, and BAC of the plants as well as the tolerable amount of the heavy metals to the bacteria

Characterization of metallothionein genes from Broussonetia papyrifera: metal binding and heavy metal tolerance mechanisms

BackgroundBroussonetia papyrifera is an economically significant tree with high utilization value, yet its cultivation is often constrained by soil contamination with heavy metals (HMs). Effective scientific cultivation management, which enhances the yield and quality of B. papyrifera, necessitates an understanding of its regulatory mechanisms in response to HM stress.ResultsTwelve Metallothionein (MT) genes were identified in B. papyrifera. Their open reading frames ranged from 186 to 372 bp, encoding proteins of 61 to 123 amino acids with molecular weights between 15,473.77 and 29,546.96 Da, and theoretical isoelectric points from 5.24 to 5.32. Phylogenetic analysis classified these BpMTs into three subclasses: MT1, MT2, and MT3, with MT2 containing seven members and MT3 only one. The expression of most BpMT genes was inducible by Cd, Mn, Cu, Zn, and abscisic acid (ABA) treatments, particularly BpMT2e, BpMT2d, BpMT2c, and BpMT1c, which showed significant responses and warrant further study. Yeast cells expressing these BpMT genes exhibited enhanced tolerance to Cd, Mn, Cu, and Zn stresses compared to control cells. Yeasts harboring BpMT1c, BpMT2e, and BpMT2d demonstrated higher accumulation of Cd, Cu, Mn, and Zn, suggesting a chelation and binding capacity of BpMTs towards HMs. Site-directed mutagenesis of cysteine (Cys) residues indicated that mutations in the C domain of type 1 BpMT led to increased sensitivity to HMs and reduced HM accumulation in yeast cells; While in type 2 BpMTs, the contribution of N and C domain to HMs’ chelation possibly corelated to the quantity of Cys residues.ConclusionThe BpMT genes are crucial in responding to diverse HM stresses and are involved in ABA signaling. The Cys-rich domains of BpMTs are pivotal for HM tolerance and chelation. This study offers new insights into the structure-function relationships and metal-binding capabilities of type-1 and − 2 plant MTs, enhancing our understanding of their roles in plant adaptation to HM stresses.

Effects of nitrogen application on ammonium assimilation and microenvironment in the rhizosphere of drip-irrigated sunflower under plastic mulch.

This study investigated the effect of nitrogen application on the rhizosphere soil microenvironment of sunflower and clarified the relationship between ammonium assimilation and the microenvironment. In a field experiment high (HN, 190 kg/hm2), medium (MN, 120 kg/hm2) and low nitrogen (CK, 50 kg/hm2) treatments were made to replicate plots of sunflowers using drip irrigation. Metagenomic sequencing was used to analyze the community structure and functional genes involved in the ammonium assimilation pathway in rhizosphere soil. The findings indicated that glnA and gltB played a crucial role in the ammonium assimilation pathway in sunflower rhizosphere soil, with Actinobacteria and Proteobacteria being the primary contributors. Compared with CK treatment, the relative abundance of Actinobacteria increased by 15.57% under MN treatment, while the relative abundance decreased at flowering and maturation stages. Conversely, the relative abundance of Proteobacteria was 28.57 and 61.26% higher in the MN treatment during anthesis and maturation period, respectively, compared with the CK. Furthermore, during the bud stage and anthesis, the abundance of Actinobacteria, Proteobacteria, and their dominant species were influenced mainly by rhizosphere soil EC, ammonium nitrogen (-N), and nitrate nitrogen (-N), whereas, at maturity, soil pH and -N played a more significant role in shaping the community of ammonium-assimilating microorganisms. The MN treatment increased the root length density, surface area density, and root volume density of sunflower at the bud, flowering, and maturity stages compared to the CK. Moreover, root exudates such as oxalate and malate were positively correlated with the dominant species of Actinobacteria and Proteobacteria during anthesis and the maturation period. Under drip irrigation, applying 120 kg/hm2 of nitrogen to sunflowers effectively promoted the community structure of ammonium-assimilating microorganisms in rhizosphere soil and had a positive influence on the rhizosphere soil microenvironment and sunflower root growth.

Chromosomal 3q amplicon encodes essential regulators of secretory vesicles that drive secretory addiction in cancer.

Cancer cells exhibit heightened secretory states that drive tumor progression. Here, we identify a chromosome 3q amplicon that serves as a platform for secretory regulation in cancer. The 3q amplicon encodes multiple Golgi-resident proteins, including the scaffold Golgi integral membrane protein 4 (GOLIM4) and the ion channel ATPase Secretory Pathway Ca2+ Transporting 1 (ATP2C1). We show that GOLIM4 recruits ATP2C1 and Golgi phosphoprotein 3 (GOLPH3) to coordinate calcium-dependent cargo loading and Golgi membrane bending and vesicle scission. GOLIM4 depletion disrupts the protein complex, resulting in a secretory blockade that inhibits the progression of 3q-amplified malignancies. In addition to its role as a scaffold, GOLIM4 maintains intracellular manganese (Mn) homeostasis by binding excess Mn in the Golgi lumen, which initiates the routing of Mn-bound GOLIM4 to lysosomes for degradation. We show that Mn treatment inhibits the progression of multiple types of 3q-amplified malignancies by degrading GOLIM4, resulting in a secretory blockade that interrupts pro-survival autocrine loops and attenuates pro-metastatic processes in the tumor microenvironment. Potentially underlying the selective activity of Mn against 3q-amplified malignancies, ATP2C1 co-amplification increases Mn influx into the Golgi lumen, resulting in a more rapid degradation of GOLIM4. These findings show that functional cooperativity between co-amplified genes underlies heightened secretion and a targetable secretory addiction in 3q-amplified malignancies.

Effects of wind-driven current and thermal dynamics in a temperate monomictic reservoir: Implications for manganese transport and treatment in water supply systems

Increasing manganese (Mn) concentrations in source water contribute to aesthetic and health-related concerns in drinking water. The challenges with Mn in drinking water primarily arise from elevated Mn concentrations in the water supply reservoir, with the inefficacy of Mn treatment largely attributed to fluctuating Mn levels in the water source. A three-dimensional Mn cycle model in a temperate monomictic reservoir, Tarago Reservoir, and a decision support system reflecting Mn variations in the local water treatment plant have been established in previous research. This study aimed to examine Mn variations from the reservoir to raw water and treated water under the influence of wind conditions during different stages of thermal structure, and discover valuable recommendations for Mn treatment in the local water supply system. We crafted 12 scenarios to scrutinize the impact of varying intensities of offshore and onshore winds on hydrodynamic processes and Mn transport during strong thermal stratification, weak thermal stratification, and turnover. The scenario analysis revealed that, during the gradual weakening of thermal stratification, offshore wind induced a substantial amount of Mn to the upper layers near the water intake point. Conversely, onshore wind hindered the upward transport of Mn. The simulated Mn in the raw water under the 12 scenarios indicated that the timing of turnover in the Tarago Reservoir is the primary concern for Mn treatment in the water treatment plant. Additionally, close attention should be given to the frequency and intensity of offshore winds during the weakening of thermal stratification.

Manganese induces podocyte injury through regulating MTDH/ALKBH5/NLRP10 axis: Combined analysis at epidemiology and molecular biology levels

Manganese (Mn) is an essential micronutrient required for various biological processes but excess exposure to Mn can cause neurotoxicity. However, there are few reports regarding the toxicity effect of Mn on the kidney as well as the underlying molecule mechanism. Herein, in vivo experiments were adopted to assess the toxicity effects associated with Mn, and found that chronic Mn treatment induced the injury of glomerular podocytes but not renal tubule in rats. Genome-wide CRISPR/Cas9 knockout screen was then employed to explore the biotargets of the toxic effect of Mn on podocytes. Through functional analyses of the enriched candidate genes, NLRP10 was found to be significantly up-regulated and mediated Mn-induced podocyte apoptosis. Further mechanism investigation revealed that NLRP10 expression was regulated by demethylase AlkB homolog 5 (ALKBH5) in an m6A-dependent fashion upon Mn treatment. Moreover, Mn could directly bind to Metadherin (MTDH) and promoted its combination with ALKBH5 to promote NLRP10 expression and cell apoptosis. Finally, logistic regressions, restricted cubic spline regressions and uniform cubic B-spline were used to investigate the association between Mn exposure and the risk of chronic kidney disease (CKD). A U-shaped nonlinear relationship between CKD risk and plasma Mn level, and a positive linear relationship between CKD risk and urinary Mn levels was found in our case-control study. To sum up, our findings illustrated that m6A-dependent NLRP10 regulation is indispensable for podocyte apoptosis and nephrotoxicity induced by Mn, providing fresh insight into understanding the health risk of Mn and a novel target for preventing renal injury in Mn-intoxicated patients.

Nitrogen addition changed soil fungal community structure and increased the biomass of functional fungi in Korean pine plantations in temperate northeast China

Nitrogen (N) deposition is a global environmental issue that can have significant impacts on the community structure and function in ecosystems. Fungi play a key role in soil biogeochemical cycles and their community structures are tightly linked to the health and productivity of forest ecosystems. Based on high-throughput sequencing and ergosterol extraction, we examined the changes in community structure, composition, and biomass of soil ectomycorrhizal (ECM) and saprophytic (SAP) fungi in 0–10 cm soil layer after 8 years of continuous N addition and their driving factors in a temperate Korean pine plantation in northeast China. Our results showed that N addition increased fungal community richness, with the highest richness and Chao1 index under the low N treatment (LN: 20 kg N ha−1 yr−1). Based on the FUN Guild database, we found that the relative abundance of ECM and SAP fungi increased first and then decreased with increasing N deposition concentration. The molecular ecological network analysis showed that the interaction between ECM and SAP fungi was enhanced by N addition, and the interaction was mainly positive in the ECM fungal network. N addition increased fungal biomass, and the total fungal biomass (TFB) was the highest under the MN treatment (6.05 ± 0.3 mg g−1).Overall, we concluded that N addition changed soil biochemical parameters, increased fungal activity, and enhanced functional fungal interactions in the Korean pine plantation over an 8-year simulated N addition. We need to consider the effects of complex soil conditions on soil fungi and emphasize the importance of regulating soil fungal community structure and biomass for managing forest ecosystems. These findings could deepen our understanding of the effects of increased N deposition on soil fungi in temperate forests in northern China, which can provide the theoretical basis for reducing the effects of increased N deposition on forest soil.

Zinc and manganese homeostasis closely interact in mammalian cells.

Understanding the homeostatic interactions among essential trace metals is important for explaining their roles in cellular systems. Recent studies in vertebrates suggest that cellular Mn metabolism is related to Zn metabolism in multifarious cellular processes. However, the underlying mechanism remains unclear. In this study, we examined the changes in the expression of proteins involved in cellular Zn and/or Mn homeostatic control and measured the Mn as well as Zn contents and Zn enzyme activities to elucidate the effects of Mn and Zn homeostasis on each other. Mn treatment decreased the expression of the Zn homeostatic proteins metallothionein (MT) and ZNT1 and reduced Zn enzyme activities, which were attributed to the decreased Zn content. Moreover, loss of Mn efflux transport protein decreased MT and ZNT1 expression and Zn enzyme activity without changing extracellular Mn content. This reduction was not observed when supplementing with the same Cu concentrations and in cells lacking Cu efflux proteins. Furthermore, cellular Zn homeostasis was oppositely regulated in cells expressing Zn and Mn importer ZIP8, depending on whether Zn or Mn concentration was elevated in the extracellular milieu. Our results provide novel insights into the intricate interactions between Mn and Zn homeostasis in mammalian cells and facilitate our understanding of the physiopathology of Mn, which may lead to the development of treatment strategies for Mn-related diseases in the future.

Nitrogen Application Timing and Levels Affect the Fate and Budget of Fertilizer Nitrogen in the Apple-Soil System.

This study aimed to determine the effects of the nitrogen (N) application period and level on the fate of fertilizer N and the contribution of N absorption and translocation to apple organ N. Two N application periods (labeled by the 15N tracer technique in spring and summer, represented by SP and SU, respectively) and three N levels (N0, MN, and HN) were used to determine the physiological indexes and aboveground, root, and soil 15N content of 4-year-old dwarf ('Red Fuji'/M9T337) and arborized ('Red Fuji'/Malus hupehensis Rehd.) apple trees. The results showed that HN led to shoot overgrowth, which was not conducive to the growth of the apple root system (root length, root tips, root surface area, and root volume) or the improvement of root activity. The contribution of soil N to apple organ N accounted for more than 50%, and the contribution of N application in summer to fruit N was higher than that in spring. Under HN treatment, the proportion of soil N absorbed by trees decreased, while that of fertilizer N increased; however, the highest proportion was still less than 50%, so apple trees were highly dependent on soil N. Under MN treatment, fertilizer N residue was similar to soil N consumption, and soil N fertility maintained a basic balance. Under HN treatment, fertilizer N residue was significantly higher than soil N consumption, indicating that excessive N application increased fertilizer N residue in the soil. Overall, the 15N utilization rate of arborized trees (17.33-22.38%) was higher than that of dwarf trees (12.89-16.91%). A total of 12.89-22.38% of fertilizer 15N was absorbed by trees, 30.37-35.41% of fertilizer 15N remained in the soil, and 44.65-54.46% of fertilizer 15N was lost. The 15N utilization rate and 15N residual rate of summer N application were higher than those of spring N application, and the 15N loss rate was lower than that of spring N application. High microbial biomass N (MBN) may be one of the reasons for the high N utilization rate and the low loss rate of N application in summer.