Fixation Activity Research Articles

Azotobacter vinelandii N 2 fixation increases in co-culture with the PGPR Bacillus subtilis in a nitrogen concentration-dependent manner

ABSTRACT Biological nitrogen fixation (BNF) is an essential source of new nitrogen (N) for terrestrial ecosystems. The abiotic factors regulating BNF have been extensively studied in various ecosystems and laboratory settings. Despite this, our understanding of the impact of neighboring bacteria on N 2 fixer activity remains limited. Here, we explored this question using a co-culture of the two model species: the free-living diazotroph Azotobacter vinelandii and the non-fixing plant growth-promoting rhizobacteria Bacillus subtilis . We observed that the interaction between the two bacteria was modulated by N availability. Under N-replete conditions, B. subtilis outcompeted A. vinelandii in the co-culture. Under N-limiting conditions, BNF activity by A. vinelandii was enhanced in the presence of B. subtilis . Reciprocally, the presence of A. vinelandii repressed sporulation by B. subtilis and supported its growth likely through N transfer. N inputs by A. vinelandii were doubled in the presence of B. subtilis compared to the monoculture, primarily due to the retention of a robust N 2 fixation activity in the stationary phase. A proteomic analysis revealed that A. vinelandii N metabolism, particularly the molybdenum nitrogenase isoform protein levels (NifK and NifD), was upregulated during the stationary growth phase in the presence of B. subtilis . This study revealed that N stress drives bacterial interactions and activity in a two-species community, especially in the stationary phase. IMPORTANCE Reducing inputs of chemical N fertilizers is essential to develop a more sustainable agriculture. The stimulation of biological nitrogen fixation by N2 fixers in multispecies cultures, here the plant growth-promoting rhizobacteria Azotobacter vinelandii and Bacillus subtilis , opens opportunities for the formulation of biofertilizers consortia. While most research on N2 fixation historically focussed on the exponential growth phase of microorganisms, we observed that Bacillus subtilis stimulated Azotobacter vinelandii N2 fixation mostly during the stationary phase. This result highlights that more research on the factors controlling N2 fixation repression during the stationary growth phase, especially bacteria-bacteria interactions, is eagerly needed.

Unfavorably Altered Fibrin Clot Phenotype in Women Following Postpartum Hemorrhage of Unknown Cause: Effect of Lower Coagulation Factors.

Increased clot permeability and susceptibility to lysis have been reported in women with heavy menstrual bleeding. We hypothesized that similar alterations in fibrin clot properties may also be present in women with postpartum hemorrhage (PPH) of unknown cause. To determine fibrin clot properties and their determinants in women after PPH of unknown cause. We studied 52 consecutive women, aged 35 years (27-40), after at least 3 months since PPH of unknown cause and 52 matched controls for age, weight, and fibrinogen. Coagulation factors (F), antithrombin, thrombin generation, along with a comprehensive plasma fibrin clot analysis including fibrin polymerization, clot permeability (K s), and fibrinolysis efficiency were determined. Women with PPH showed reduced activity of FII (-10.3%), FV (-6.6%), FIX (-6.5%), FX (-7.2%), and FXI (-5.7%) compared with the controls, though all values were within ranges (all p < 0.05). There were no intergroup differences in fibrinogen, FVIII, FXIII, and thrombin generation. The PPH group formed with a delay looser plasma fibrin network (K s; +16.3%, p = 0.008) with lower maximum absorbance and shorter clot lysis time (CLT; -13.5%, p = 0.001) compared with the controls. On multivariable logistic regression, PPH was independently associated with higher C-reactive protein (per 1 mg/L, odds ratio [OR] = 1.70, 95% confidence interval [CI]: 1.09-2.68), lower FII (per 1%, OR = 0.93, 95% CI: 0.89-0.98), lower FV (per 1%, OR = 0.93, 95% CI: 0.89-0.97), and shorter CLT (per 1 minute, OR = 0.94, 95% CI: 0.90-0.98). Prohemorrhagic fibrin clot properties, with lower, though normal coagulation factors, characterize women with PPH of unknown cause, which suggests novel mechanisms contributing to this type of bleeding.

Profiling of Key Hub Genes Using a Two-State Weighted Gene Co-Expression Network of 'Jao Khao' Rice under Soil Salinity Stress Based on Time-Series Transcriptome Data.

RNA-sequencing enables the comprehensive detection of gene expression levels at specific time points and facilitates the identification of stress-related genes through co-expression network analysis. Understanding the molecular mechanisms and identifying key genes associated with salt tolerance is crucial for developing rice varieties that can thrive in saline environments, particularly in regions affected by soil salinization. In this study, we conducted an RNA-sequencing-based time-course transcriptome analysis of 'Jao Khao', a salt-tolerant Thai rice variety, grown under normal or saline (160 mM NaCl) soil conditions. Leaf samples were collected at 0, 3, 6, 12, 24, and 48 h. In total, 36 RNA libraries were sequenced. 'Jao Khao' was found to be highly salt-tolerant, as indicated by the non-significant differences in relative water content, cell membrane stability, leaf greenness, and chlorophyll fluorescence over a 9-day period under saline conditions. Plant growth was slightly retarded during days 3-6 but recovered by day 9. Based on time-series transcriptome data, we conducted differential gene expression and weighted gene co-expression network analyses. Through centrality change from normal to salinity network, 111 key hub genes were identified among 1,950 highly variable genes. Enriched genes were involved in ATP-driven transport, light reactions and response to light, ATP synthesis and carbon fixation, disease resistance and proteinase inhibitor activity. These genes were upregulated early during salt stress and RT-qPCR showed that 'Jao Khao' exhibited an early upregulation trend of two important genes in energy metabolism: RuBisCo (LOC_Os10g21268) and ATP synthase (LOC_Os10g21264). Our findings highlight the importance of managing energy requirements in the initial phase of the plant salt-stress response. Therefore, manipulation of the energy metabolism should be the focus in plant resistance breeding and the genes identified in this work can serve as potentially effective candidates.

Synergistic Tuning of Heterovalent States and Oxygen-Vacancy Defect Engineering in Hydrophilic W-Doped Sb2OS2 for Enhanced Nitrogen Photoreduction to Ammonia.

Nitrogen fixation reaction via photocatalysis offers a green and promising strategy for renewable NH3 synthesis, and catalysts with high-efficiency photocatalytic properties are essential to the process. Herein, we demonstrate a W-doped Sb2OS2 bimetal oxysulfide catalyst (labeled as SbWOS) with abundant oxygen vacancies, heterovalent metal states, and hydrophilic surfaces for nitrogen photoreduction to ammonia. The SbWOS-3 with suitable W-doping exhibited excellent nitrogen fixation activity of 408.08 μmol·g-1·h-1 and an apparent quantum efficiency (AQE) of 1.88% at 420 nm and a solar-to-ammonia (STA) conversion efficiency of 0.082% in pure water under AM1.5G light irradiation. The W-doping not only transforms hydrophobic Sb2OS2 into a hydrophilic catalyst, making it easier for H2O molecules adsorbed on the SbWOS surface and catalyzed into protons, but also endows the SbWOS catalyst with rich oxygen vacancies, acting as the active sites for trapping and activating the N2 molecule, and for trapping and activating H2O to produce the protons for the N2 photocatalytic reduction reaction. The hydrazine drives the SbWOS catalyst with the heterovalent metal states, which acts as the photogenerate electrons quickly hopping between W5+ and W6+ to transfer for the N2 reduction reaction. This study provides a feasible scheme for applying oxygen vacancy defects, heterovalent metal states, and surface hydrophobic-to-hydrophilic wetting engineering in bimetal oxysulfide for N2 photoreduction to ammonia.

Gene therapy for hemophilia

Concept Gene therapy with adeno-associated virus (AAV) vectors treats hemophilia A or B by delivering a functional F8 or F9 gene to hepatocytes. This single infusion enables endogenous production of FVIII or FIX protein, reducing bleeding in patients. Evolution Long-term clinical studies have provided insight into the efficacy, safety, and durability of AAV-mediated gene therapies for hemophilia A and B. Gene therapies have now been approved for hemophilia A (valoctocogene roxaparvovec) and hemophilia B (etranacogene dezaparvovec; fidanacogene elaparvovec) in select regions. Application The approved gene therapies are associated with a strong reduction in bleeding tendency and increased FVIII or FIX activity levels, without the need for additional FVIII or FIX replacement therapies, in the vast majority of patients. Future Steps Improvements in AAV technology, protein expression, and immunogenicity may render AAV-mediated gene therapies more efficient, longer lasting and safer for people with hemophilia A or B.

Recent Advances in Photocatalytic Nitrogen Fixation Based on Two‐Dimensional Materials

AbstractUtilizing solar energy for photocatalytic nitrogen fixation has been extensively regarded as a promising avenue towards renewable nitrogen energy production. 2D materials, renowned for their unique structures and properties, have sparked remarkable advancements in the realm of energy and environment sciences. In this review, we delve into the recent advancements pertaining to 2D materials for solar‐driven photocatalytic nitrogen fixation. This encompasses a diverse array of materials, including metal carbides/nitrides (MXenes), transition metal dichalcogenides (TMDs or TMDCs), graphitized carbon nitride (g‐C3N4), metal‐organic frameworks (MOFs), covalent organic frameworks (COFs), and covalent triazine‐based frameworks (CTFs). We offer a fundamental understanding of the functionalities exhibited by various 2D materials in enhancing photocatalytic nitrogen fixation activity. The photocatalytic properties of these 2D materials are meticulously examined from multiple perspectives, including visible light absorption capabilities, charge transfer within the energy band, and reaction mechanisms. Finally, we present an in‐depth discussion on the existing challenges and prospects surrounding the application of 2D materials in photocatalytic nitrogen fixation.

Substrate Competition of Diazotrophic Nitrous Oxide Assimilation Over Dinitrogen Fixation

AbstractNitrous oxide (N2O) is a potent greenhouse gas and is depleting the stratospheric ozone layer. Diazotrophic N2O assimilation to biomass represents a novel biological N2O consumption pathway in addition to canonical denitrification. Thermodynamically, N2O assimilation is more favorable than dinitrogen (N2) fixation in natural environments, especially under higher N2O concentration and cooler conditions. Via isotopic tracing experiments, N2O assimilation was detected on cultured diazotrophs Crocosphaera and Trichodesmium with specific rates from 1.27 ± 0.16 × 10−4 to 2.00 ± 0.25 × 10−4 hr−1 under elevated [N2O]/[N2] conditions (0.0005–0.01) within 24‐hr incubation. The rates of N2O assimilation during the light and dark periods were statistically insignificant compared with N2 fixation activity. In a eutrophic estuary, N2O assimilation was not detected in the absence of diazotrophic activity. A competitive substrate kinetic model with experimentally calibrated parameters successfully quantified rate ratios of N2O assimilation and N2 fixation in varying substrate concentrations. The low [N2O]/[N2] ratio in natural conditions leads to N2O assimilation rate being &lt;0.1% of N2 fixation rate, rendering negligible impact of N2O assimilation. The model was also used to predict the time required for experimental detection of N2O assimilation in isotopic tracing experiments under varying [N2O]/[N2] ratios. This study enhances the mechanistic understanding of N2O assimilation by diazotrophs, broadening the microbial nitrogen cycle by a potential N2O sink and nitrogen source for production.

Early diagnosis, monitoring, profiling, and management of bayberry twig blight disease by nitrogen metabolism

Pestalotiopsis versicolor, pathogen of Bayberry Twig Blight Disease causes wilt and leaf spots thereby reducing the photosynthetic area which ultimately leads to production of small fruits with poor nutritional quality. Due to heavy dependence on chemicals with its detrimental effect, new biofriendly measures are sort. Surface-enhanced Raman scattering technology was used in early discovery and monitoring of the disease progression in bayberry seedlings. The spectra 1454.46 cm−1 was inferred as the fingerprint of the fungus. MgO nano-bioprotectant (MgONBs) antifungal mechanism of action was studied via transcriptomic and metabolomic profiling at 12 and 24 h post-inoculation (hpi) with P. versicolor and metagenomics profiling at 7 and 14 days post-inoculation (dpi) with P. versicolor. MgONBs enhanced the recruitment of Bradyrhizobium to overcome the attack of P. versicolor. Nitrogen fixation activities in the diseased leaves at 7 and 14 dpi were significantly reduced, while it was significantly increased from 17.74 % in the diseased leaves to 26.79 % in the diseased leaves treated with MgONBs at 14 dpi. Thus, activating bayberry defense by increasing its nitrogen metabolism. In addition, in MgONBs group compared to control, urea, L-Methionine sulfone, and 5-Aminosalicylic acid compounds were activated which enriched its defense and signaling pathways. Upregulated differentially expressed genes in MgONBs relative to the control at 12 and 24 hpi mapped to KEGG pathways involved in amino acid metabolism which was tightly linked to photosynthesis gene (CJ030_MR1G012863). Our results reveals the mechanism of action of MgONBs in combatting phytopathogens.

PBPK modeling of recombinant factor IX Fc fusion protein (rFIXFc) and rFIX to characterize the binding to type 4 collagen in the extravascular space.

Patients with severe and sometimes moderate hemophilia B are prophylactically treated with factor IX concentrates to prevent bleeding. For some time now, various extended terminal half-life (EHL) recombinant factor IX concentrates are available allowing less frequent administration during prophylaxis in comparison to standard half-life recombinant FIX (rFIX). Especially, recombinant FIX-Fc fusion protein (rFIXFc; Alprolix®) exhibits a rapid distribution phase, potentially due to binding to type IV collagen (Col4) in the extravascular space. Studies suggest that the presence of extravascular rFIXFc is protective against bleeding as without measurable FIX activity in plasma, and no extra bleeding seems to occur. The physiologically based pharmacokinetic (PBPK) model for rFIXFc which we describe in this study, is able to accurately predict the observed concentration-time profiles of rFIXFc in plasma and is able to quantify the binding of rFIXFc to Col4 in the extravascular space after an intravenous dose of 50 IU/kg rFIXFc in a male population. Our model predicts that the total AUC of rFIXFc bound to Col4 in the extravascular space is approximately 19 times higher compared to the AUC of rFIXFc in plasma. This suggests that rFIXFc present in the extravascular compartment may play an important role in achieving hemostasis after rFIXFc administration. Further studies on extravascular distribution of rFIXFc and the distribution profile of other EHL-FIX concentrates are needed to evaluate the predictions of our PBPK model and to investigate its clinical relevance.

Invasive procedures and surgery following etranacogene dezaparvovec gene therapy in people with hemophilia B

BackgroundLittle information regarding the management of invasive procedures in people with hemophilia B (HB) after undergoing gene therapy is available. Here, we report the management of invasive procedures in people with severe or moderately severe HB who had previously been treated with etranacogene dezaparvovec in the phase 2b and phase 3 HOPE-B clinical trials (NCT03489291 and NCT03569891). Objectives▪. MethodsThis retrospective analysis included invasive procedures performed within 3 and 2 years following a single infusion of 2 × 1013 gc/kg of etranacogene dezaparvovec in participants in the phase 2b and HOPE-B trials, respectively. Data for factor (F)IX dosing, duration of postoperative FIX use, FIX activity prior to invasive procedures, and postoperative bleeds were collected and analyzed. ResultsThe analysis included 64 procedures in 29 participants: 9 major surgeries, 24 minor surgeries, 11 endoscopies, 3 endoscopies with biopsy/polypectomy, and 17 dental procedures. Uncontaminated endogenous FIX activity corresponded to mild hemophilia or normal levels prior to 98% of all procedures, with a median endogenous FIX activity of 43.8 IU/dL (range, 3.1-113 IU/dL). All major surgeries were managed with exogenous FIX, 67% with ≤4 days of FIX infusion. Most minor surgeries (88%), endoscopies (82%), and dental procedures (94%) were managed with no or a single FIX infusion. Postoperative bleeds occurred after 1 minor surgery and 4 dental procedures. There were no symptomatic thrombotic events or FIX inhibitor developments. ConclusionEtranacogene dezaparvovec has the potential to facilitate perioperative management in people with HB by reducing the need for perioperative exogenous FIX and its associated risks.

Surface ion-exchange induced Bi-rich Bi12O17Cl2/BiOCOOH/Bi2MoO6 heterojunction with oxygen vacancies for enhanced photocatalytic nitrogen fixation

Photocatalytic nitrogen reduction presents a promising technology for environmentally friendly ammonia synthesis under mild conditions. However, the performance of photocatalysts is often hindered by high charge carrier recombination and insufficient adsorption and activation of nitrogen molecules. A novel Bi12O17Cl2/BiOCOOH/Bi2MoO6 heterojunction photocatalyst was successful synthesis through surface ion-exchange technique by potassium chloride. The introduction of Bi-rich Bi12O17Cl2 on BiOCOOH/Bi2MoO6 heterojunction not only improves electron transfer efficiency due to the dual type-II heterojunction effect but also facilitates on-site N2 adsorption and activation for solar ammonia production by promoting oxygen vacancies. The high photocatalytic nitrogen fixation activity of the Bi12O17Cl2/BiOCOOH/Bi2MoO6 was 107.78 μmol g−1 h−1 without any sacrificial agent. DFT calculations indicate that oxygen vacancies serve as the active site for adsorbed N2, the hydrogenation process preferentially forms on the distal N2 atom with a lower activation energy about 0.6 eV. Therefore, the combination of oxygen vacancies and band engineering accelerates the production of ammonia. This endeavor holds the potential to unleash the capabilities of engineering for Bi-rich heterojunctions materials with oxygen vacancies, thereby achieving high-efficiency solar-driven N2-to-NH3 conversion in aqueous environments.

High biological N fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the Qinghai‒Tibet Plateau

Biological nitrogen (N) fixation is a pivotal N source in N-deficient ecosystems. The Qinghai‒Tibet Plateau (QTP) region, which is assumed to be N limited and suboxic, is an ideal habitat for diazotrophs. However, the diazotrophic communities and associated N fixation rates in these high-altitude alpine permafrost QTP rivers remain largely unknown. Herein, we examined diazotrophic communities in the sediment and biofilm of QTP rivers via the nitrogenase (nifH) gene sequencing and assessed their N fixing activities via a 15N isotope incubation assay. Strikingly, anaerobic heterotrophic diazotrophs, such as sulfate- and iron-reducing bacteria, had emerged as dominant N fixers. Remarkably, the nifH gene abundance and N fixation rates increased with altitude, and the average nifH gene abundance (2.57 ± 2.60 × 108 copies g−1) and N fixation rate (2.29 ± 3.36 nmol N g−1d−1) surpassed that documented in most aquatic environments (nifH gene abundance: 1.31 × 105 ∼ 2.57 × 108 copies g−1, nitrogen fixation rates: 2.34 × 10−4 ∼ 4.11 nmol N g−1d−1). Such distinctive heterotrophic diazotrophic communities and high N fixation potential in QTP rivers were associated with low-nitrogen, abundant organic carbon and unique C:N:P stoichiometries. Additionally, the significant presence of psychrophilic bacteria within the diazotrophic communities, along with the enhanced stability and complexity of the diazotrophic networks at higher altitudes, clearly demonstrate the adaptability of diazotrophic communities to extreme cold and high-altitude conditions in QTP rivers. We further determined that altitude, coupled with organic carbon and phosphorus, was the predominant driver shaping diazotrophic communities and their N-fixing activities. Overall, our study reveals high N fixation potential in N-deficient QTP rivers, which provides novel insights into nitrogen dynamics in alpine permafrost rivers.

Z-scheme metal organic framework/Ag@AgCl heterojunction photocatalysts with elevated photocatalytic N2 fixation activity

As one of the most consumed chemical reagents, ammonia (NH3) has a wide range of applications in many fields. The demand for ammonia may continue to increase with the advancement of technology and the acceleration of industrialization. The traditional high energy consumption and high pollution ammonia synthesis methods (Haber-Bosch) need to be optimized and improved to reduce environmental pollution and energy dependence. In this work, a series of Z-scheme NM/Ag@AgCl heterojunctions were prepared as catalysts for the research of photocatalytic nitrogen fixation. By in-situ photodeposition, Ag@AgCl was uniformly distributed on the NM surface, and the interfaces of different substances were tightly bonded. The SPR effect that generated by Ag nanoparticles significantly enhanced the light energy absorption performance of heterojunction materials. In the ESR spectra, the signal peak intensity of NM/Ag@AgCl was higher than that of NM under light condition. Constructing of heterojunction was beneficial to the formation of Ti3+. The strong built-in electric field among NM and AgCl promoted the generation of Z-scheme heterojunction. NM/Ag@AgCl had sufficient redox potential to overcome thermodynamic barriers and drive the catalytic reaction. Without adding any sacrificial reagent, the ammonia production of NM/Ag@AgCl-3 reached 76.7 µmol g−1 h−1 under full spectrum radiation. The rate of ammonia formation of NM/Ag@AgCl was almost seven times than that of NM. The synergistic effect between NM and Ag@AgCl optimized the photogenerated carrier separation path. This work provided a new vision for the practical application of efficient photocatalytic N2 reduction.

Zinc Oxide Nanoparticles in the “Soil–Bacterial Community–Plant” System: Impact on the Stability of Soil Ecosystems

The use of man-made nanoparticles (NPs) has increased exponentially in recent years, many of which accumulate in significant quantities in soil, including through use in agriculture as nanofertilizers and nanopesticides. ZnO NPs are more environmentally friendly but have specific antimicrobial activity, which can affect soil microbiota, thereby influencing key microbial processes such as mineralization, nitrogen fixation and plant growth-promoting activities. Their behavior and persistence in soil depend on their chemical nature and soil characteristics. This review summarizes the applications of ZnO NPs in soil systems and their effects on various plants and soil microorganisms, particularly rhizobacteria that promote plant growth. A stimulating effect of ZnO NPs on the morphometric and biochemical characteristics of plants, as well as on soil microbiota and its activity at relatively low concentrations of up to 500 mg/mL and 250 mg/kg, respectively, is observed. As the concentration of ZnO NPs increases above these limits, toxic effects appear. The different effects of ZnO NPs are related to their size, dose, duration of exposure, solubility in water, as well as soil type, acidity and organic matter content. The review substantiates the need to study the behavior of ZnO NPs in the “soil-plant-microbiota” system for the possibility of using nanotechnologies in the agricultural industry and ensuring the safety of agricultural products.

Assessing the Alteration of Soil Quality under Long-Term Fertilization Management in Farmland Soil: Integrating a Minimum Data Set and Developing New Biological Indicators

The key role of soil quality improvement in achieving sustainable agricultural development based on highly intensive use of farmland is increasingly being recognized, as is the ponderance of suitable evaluation of the soil quality. The overarching goal of this study was to determine an accurate assessment framework by the comparison of the scoring function (linear and non-linear) and integration method (area and weighted additive), which integrally evaluates the soil quality of an eleven-year field fertilization experiment (including CK, no fertilizer; CF, conventional fertilization; SF, formulated fertilization; SFO, SF with organic fertilizer). Thirty-three properties, including eighteen physiochemical-related and fifteen biological-related properties, associated with soil functions were measured as potential soil quality indicators, and the soil multifunctionality (SMF) was applied to validate the soil quality indices (SQIs). Principal component analysis and relationship analysis were used with indicators sensitive to management to determine a minimum data set (MDS). The results showed that the electrical conductivity, large macroaggregate-associated total nitrogen, small macroaggregate-associated organic carbon, carbon fixation, and enzyme activities of phenol oxidase and cellulase were chosen as the MDS. All the SQIs were significantly correlated with the SMF (p &lt; 0.05). The fertilization strategies affected most indicators in different ways, and the index developed using the non-linear function and weighted additive integration method (SQI-NL) had the best sensibility and discriminability. The SQI value with the SQI-NL-MDS method was higher following the fertilization treatments than that of no fertilizer (p &lt; 0.05), and the treatment of the organic fertilizer had the highest SQI value (0.66). Soil quality evaluation in long-term fertilized farmland suggested that the soil quality constraints between treatments of synthetic and organic fertilizer are related to the soil functions of nutrient cycling and sustain biological activity due to their higher contribution rates to the SQI in the organic fertilizer treatment, which provides insights into ways to reduce the gap in soil quality. The framework method can provide an accurate quantitative tool for the evaluation of soil quality from the target indicators by bridging management objectives and field-level actions.

Assessment of moss-associated biological nitrogen fixation of dominant moss species in mature black spruce forests in Eastern Canada

Biological nitrogen fixation (BNF) by bryophytes is an essential source of new nitrogen in nitrogen-limited boreal ecosystems. This assessment is, however, primarily based on reports from northern Europe and, to a lesser extent, Western North America. A more systematic and extensive evaluation of nitrogen fixation by moss is required to close current gaps in records of moss BNF and better assess the importance of bryophytes on N input in boreal ecosystems. Here, we evaluated nitrogen fixation activity and contribution to N input of dominant bryophyte species in black spruce forests from Eastern Canada. We assessed the relative abundance, BNF activity, and relative contribution to nitrogen input on five sites along a 600 km transect. We report that several moss species contribute to nitrogen input but that Ptilium crista-castrensis is the main contributor. Estimated nitrogen input by mosses (≪ 1 kg·ha−1·year−1) is in the low range of N inputs reported in the literature and is consistent with activities reported elsewhere for similar species, N deposition, and forest age. Results show that atmospheric deposition, while low, remains a more significant source of exogenous N to mature black spruce forests than bryophytes.

Characterization of recombinant factor IX fusion proteins enabling subcutaneous administration

BackgroundThe X-linked bleeding disorder hemophilia B, caused by mutation(s) in the coagulation factor (F)IX gene, leads to partial or total loss of its function, requiring lifelong FIX replacement therapy. Although new recombinant FIX (rIX) therapeutics like albumin fusion proteins (rIX-FP) enable longer plasma half-life and thus less frequent administration, the complexity of intravenous (i.v.) injection remains. ObjectivesThe study aimed to characterize rIX-FP variants with anticipated enhanced specific activity, which would leverage rIX-FP’s superior pharmacokinetic profile with beneficial characteristics for subcutaneous (s.c.) administration. MethodsTwo rIX-FP variants, R338L (“Padua variant”) and R338L/E410K, were characterized in vitro. Pharmacokinetic profiles of FIX antigen and activity levels were evaluated in FIX-deficient mice after i.v. and s.c. administration of these variants (dosing based on antigen levels). The efficacy of the most promising variant was tested after i.v. and s.c. administration (dosing based on activity) in a tail clip bleeding model. A marketed wild-type (WT) rIX-FP product served as the comparator. ResultsBoth rIX-FP variants showed a 4- to 5-fold increase in specific activity in vitro compared with rIX(WT)-FP, while FXIa-mediated activation was the fastest for rIX(WT)-FP and rIX(R338L)-FP. Compared with rIX(WT)-FP and rIX(R338L/E410K)-FP, rIX(R338L)-FP exhibited higher FIX activity exposure after i.v. and s.c. administration and demonstrated comparable efficacy with rIX(WT)-FP in reducing bleeding time and blood loss in FIX-deficient mice requiring ∼4 times lower protein amount. ConclusionrIX(R338L)-FP was shown to be a promising candidate for s.c. administration, exhibiting increased specific activity combined with higher activity-based exposure and indicating efficacy at a lower protein dose.

Fronts divide diazotroph communities in the Southern Indian Ocean.

Dinitrogen (N2) fixation represents a key source of reactive nitrogen in marine ecosystems. While the process has been rather well-explored in low latitudes of the Atlantic and Pacific Oceans, other higher latitude regions and particularly the Indian Ocean have been chronically overlooked. Here, we characterize N2 fixation and diazotroph community composition across nutrient and trace metals gradients spanning the multifrontal system separating the oligotrophic waters of the Indian Ocean subtropical gyre from the high nutrient low chlorophyll waters of the Southern Ocean. We found a sharp contrasting distribution of diazotroph groups across the frontal system. Notably, cyanobacterial diazotrophs dominated north of fronts, driving high N2 fixation rates (up to 13.96nmol N l-1 d-1) with notable peaks near the South African coast. South of the fronts non-cyanobacterial diazotrophs prevailed without significant N2 fixation activity being detected. Our results provide new crucial insights into high latitude diazotrophy in the Indian Ocean, which should contribute to improved climate model parameterization and enhanced constraints on global net primary productivity projections.

Evaluating Factor VIII Concentrates Using Clot Waveform Analysis.

Background/Objectives: FVIII reagent activity varies across different assays, as well as activated partial thromboplastin time (APTT) reagents. The hemostatic ability of various FVIII reagents was examined via clot waveform analysis (CWA). Methods: APTT was measured using 12 APTT reagents, a small amount of tissue factor-induced FIX activation (sTF/FIXa) and a small amount of thrombin time (sTT) in order to examine 10 FVIII reagents and reference plasma (RP) using CWA. FVIII activity was measured using CWA-APTT, a chromogenic assay, or CWA-sTT. Results: Although the peak time (PT) and peak height (PH) of the CWA-APTT were markedly different in different FVIII reagents using several APTT reagents, the PTs of CWA-APTT were generally normal or shortened and the PHs of CWA-APTT were generally lower than those of RP. The FVIII activity varied, as evaluated using APTT, and was higher when using the CWA-sTT method than the APTT or chromogenic methods. CWA-sTT showed an elevated second peak of first DPH in all FVIII reagents, and both CWA-sTF/FIXa and CWA-sTT were enhanced using APTT reagents. Conclusions: Our evaluation of the hemostatic ability of FVIII reagents varied among APTT reagents. CWA-sTT can be used to further evaluate the hemostatic ability of an FVIII concentrate based on thrombin burst.

Isolation and characterization of plant growth-promoting bacteria from medicinal plants Java cardamom (Amomum compactum) and bitter ginger (Zingiber zerumbet)

Abstract. Geraldi A, Clement C, Pertiwi MD, Lestari Y, Parinnata DH, Arsad RN, Sadikin RA, Luqman A, Santoso H, Kristanti AN, Manuhara YSW, Wibowo AT. 2024. Isolation and characterization of plant growth-promoting bacteria from medicinal plants Java cardamom (Amomum compactum) and bitter ginger (Zingiber zerumbet). Biodiversitas 25: 2556-2564. Java cardamom (Amomum compactum) and bitter ginger (Zingiber zerumbet) are valuable medicinal plants native to Indonesia with significant economic and pharmacological importance. While their pharmacological properties have been extensively studied, little is known about the role of their endophytic bacterial communities in influencing plant growth and development. Understanding the interactions between these plants and their associated bacteria could provide insights into novel strategies to enhance their cultivation. This study investigates the potential of endophytic bacteria associated with A. compactum and Z. zerumbet in promoting plant growth. Samples were collected from leaf, rhizome, and rhizosphere soil, followed by isolation and characterization of bacterial strains. Molecular identification revealed the presence of Methylobacterium aquaticum, Paenibacillus tyrfis, Priestia megaterium strain 1, Priestia aryabhattai, and Microbacterium arthrosphaerae among the isolated strains from A. compactum, while strains isolated from Z. zerumbet included Enterobacter mori, Pr. megaterium strain 2, and Pr. megaterium strain 3. Those results demonstrated that Pr. megaterium strains exhibited strong phosphate solubilization, nitrogen fixation, and cellulolytic activity, while Pr. aryabhattai and Pa. tyrfis showed significant nitrogen fixation and cellulolytic potential. Additionally, M. aquaticum, Pa. tyrfis, and Pr. aryabhattai exhibited anti-phytopathogenic activity against Xanthomonas campestris. These findings not only highlight the diverse beneficial attributes of the isolated bacterial strains but also suggest their potential application as biofertilizers and biocontrol agents in agriculture, offering a promising avenue for sustainable farming practices.