Direct Synthesis of α- and ß-2'-Deoxynucleosides with Stereodirecting Phosphine Oxide via Remote Participation.

2'-Deoxynucleosides and analogues play a vital role in drug development, but their preparation remains a significant challenge. Previous studies have focused on ß-2'-deoxynucleosides with the natural ß-configuration. In fact, their isomeric α-2'-deoxynucleosides also exhibit diverse bioactivities and even better metabolic stability. Herein, we report that both α- and ß-2'-deoxynucleosides can be prepared with high yields and stereoselectivity using a remote directing diphenylphosphinoyl (DPP) group. It is particularly efficient to prepare α-2'-deoxynucleosides with an easily accessible 3,5-di-ODPP donor. Instead of acting as a H-bond acceptor on a 2-(diphenylphosphinoyl)acetyl (DPPA) group in our previous studies for syn-facial O-glycosylation, the phosphine oxide moiety here acts as a remote participating group to enable highly antifacial N-glycosylation. This proposed remote participation mechanism is supported by our first characterization of an important 1,5-briged P-heterobicyclic intermediate via variable-temperature NMR spectroscopy. Interestingly, antiproliferative assays led to a α-2'-deoxynucleoside with IC50 values in the low micromole range against central nervous system tumor cell lines SH-SY5Y and LN229, whereas its ß-anomer exhibited no inhibition at 100 µM. Furthermore, the DPP group significantly enhanced the antitumor activities by 10 times.

Feasibility Analysis of Individualized Low Flow Rate Abdominal Contrast-Enhanced Computed Tomography in Chemotherapy Patients: Dual-Source Computed Tomography With Low Tube Voltage.

PURPOSE: The aim of the study is to investigate the feasibility of using dual-source computed tomography (CT) combined with low flow rate and low tube voltage for postchemotherapy image assessment in cancer patients. METHODS: Ninety patients undergoing contrast-enhanced CT scans of the upper abdomen were prospectively enrolled and randomly assigned to groups A, B, and C (n = 30 each). In group A, patients underwent scans at 120 kVp with 448 mgI/kg. Patients in group B underwent scans at 100 kVp with 336 mgI/kg. Patient in group C underwent scans at 70 kVp with of 224 mgI/kg. Quantitative measurements including the CT number, standard deviation of CT number, signal-to-noise ratio, contrast-to-noise ratio, subjective reader scores, and the volume and flow rate of contrast agent were evaluated for each group. RESULTS: There was no statistically significant difference in the subjective image scores within the three groups except for the kidney (all P > 0.05). Group C showed significantly higher CT values, lower noise levels, and higher signal-to-noise ratio and contrast-to-noise ratio values in the majority of the regions of interest compared to the other groups (P < 0.05). In group C, the contrast agent dose was decreased by 46% compared to group A (79.48 ± 12.24 vs 42.7 ± 8.6, P < 0.01), and the contrast agent injection rate was reduced by 22% (2.7 ± 0.41 vs 2.1 ± 0.4, P < 0.01). CONCLUSIONS: The use of 70 kVp tube voltage combined with low iodine flow rates prove to be a more effective approach in solving the challenge of compromised blood vessels in postchemotherapy tumor patients, without reducing image quality and diagnostic confidence.

Effect of early serum phosphate disorder on in-hospital and 28-day mortality in sepsis patients: a retrospective study based on MIMIC-IV database.

BACKGROUND: This study aims to assess the influence of early serum phosphate fluctuation on the short-term prognosis of sepsis patients. METHODS: This retrospective study used the Medical Information Mart for Intensive Care IV database to analyze serum phosphate levels in sepsis patients within 3 days of ICU admission. According to the absolute value of delta serum phosphate (the maximum value minus the minimum value of serum phosphorus measured within three days), the patients were divided into four groups, 0-1.3, 1.4-2.0, 2.1-3.1, and ≥ 3.2 mg/dl. Meanwhile, the direction of delta serum phosphate was compared. With the serum phosphate change group of 0-1.3 mg/dl as the reference group, the relationship between delta serum phosphate and in-hospital mortality and 28-day mortality was analyzed by multivariate Logistics regression analysis. RESULTS: The study involved 1375 sepsis patients. Serum phosphate changes (0-1.3, 1.4-2.0, 2.1-3.1, and ≥ 3.2 mg/dl) correlated with in-hospital and 28-day mortality variations (p = 0.005, p = 0.008). Much higher serum phosphate fluctuation elevated in-hospital and 28-day mortality. Compared to the 0-1.3 mg/dl change group, adjusted odds ratios (OR) in other groups for in-hospital mortality were 1.25 (0.86-1.81), 1.28 (0.88-1.86), and 1.63 (1.10-2.43), and for 28-day mortality were 1.21 (0.86-1.72), 1.10 (0.77-1.57), and 1.49 (1.03-2.19). Under the trend of increasing serum phosphate, the ORs of in-hospital mortality and 28-day mortality in ≥ 3.2 mg/dl group were 2.52 and 2.01, respectively. CONCLUSION: In conclude, the delta serum phosphate ≥ 3.2 mg/dl was associated with in-hospital mortality and 28-day mortality in patients with sepsis.

Compensatory remodeling of a septo-hippocampal GABAergic network in the triple transgenic Alzheimer's mouse model.

BACKGROUND: Alzheimer's disease (AD) is characterized by a progressive loss of memory that cannot be efficiently managed by currently available AD therapeutics. So far, most treatments for AD that have the potential to improve memory target neural circuits to protect their integrity. However, the vulnerable neural circuits and their dynamic remodeling during AD progression remain largely undefined. METHODS: Circuit-based approaches, including anterograde and retrograde tracing, slice electrophysiology, and fiber photometry, were used to investigate the dynamic structural and functional remodeling of a GABAergic circuit projected from the medial septum (MS) to the dentate gyrus (DG) in 3xTg-AD mice during AD progression. RESULTS: We identified a long-distance GABAergic circuit that couples highly connected MS and DG GABAergic neurons during spatial memory encoding. Furthermore, we found hyperactivity of DG interneurons during early AD, which persisted into late AD stages. Interestingly, MS GABAergic projections developed a series of adaptive strategies to combat DG interneuron hyperactivity. During early-stage AD, MS-DG GABAergic projections exhibit increased inhibitory synaptic strength onto DG interneurons to inhibit their activities. During late-stage AD, MS-DG GABAergic projections form higher anatomical connectivity with DG interneurons and exhibit aberrant outgrowth to increase the inhibition onto DG interneurons. CONCLUSION: We report the structural and functional remodeling of the MS-DG GABAergic circuit during disease progression in 3xTg-AD mice. Dynamic MS-DG GABAergic circuit remodeling represents a compensatory mechanism to combat DG interneuron hyperactivity induced by reduced GABA transmission.

Cretaceous lophocoronids with short proboscis and retractable female genitalia provide the earliest evidence for their feeding and oviposition habits.

We describe two new species of Lophocoronidae: Acanthocorona hedida Zhang, Shih and Engel sp. n. and Acanthocorona venulosa Zhang, Shih and Engel sp. n., and an undetermined specimen from mid-Cretaceous Kachin amber. Phylogenetic analysis of basal lepidopteran lineages, including three extinct families, was undertaken. The analysis supported monophyly of Glossata although internal relationships remain controversial. Acanthocorona and Lophocorona form a monophyletic group. It is likely that short and simply structured proboscides of Acanthocorona were used to sip water droplets, pollination drops from gymnosperms, nectar from early flowers, or sap from injured leaves. Both retracted and extended ovipositors are preserved in the material reported here, revealing their morphology and indicating that these Cretaceous lophocoronids inserted eggs into the tissues of their host plants.

Mesenchymal stem cells-derived HIF-1α-overexpressed extracellular vesicles ameliorate hypoxia-induced pancreatic ß cell apoptosis and senescence through activating YTHDF1-mediated protective autophagy.

Pancreatic islet transplantation is an ideal treatment strategy for type 1 diabetes mellitus (T1DM), but hypoxia-induced pancreatic ß cell death after islet transplantation is the huge obstacle that causes failure of this therapy. Thus, it become necessary to improve pancreatic ß cell viability under hypoxic conditions. In the present study, we designed mesenchymal stem cells (MSCs)-derived hypoxia-inducible factor 1α (HIF-1α)-overexpressed extracellular vesicle (EVs) (HIF-1α-EVs) and found that HIF-1α-EVs was effectively to promote cell viability and autophagy, and suppress cell apoptosis and senescence in the hypoxia-treated pancreatic ß cells. In addition, blockage of autophagy by its inhibitor 3-methyladenine (3-MA) abrogated the rescuing effects of HIF-1α-EVs on hypoxia-induced pancreatic ß cell death. Then, the potential underlying mechanisms by which HIF-1α-EVs triggered protective autophagy were uncovered, and we found that HIF-1α-EVs upregulated YTHDF1, resulting in the upregulation of autophagy-associated proteins (ATG5, ATG2A and ATG14), which were abrogated by deleting m6A writer METTL3. Finally, we verified that HIF-1α-EVs rescued cell viability, and reversed hypoxia-induced pancreatic ß cell apoptosis and senescence in a YTHDF1-dependent manner. Collectively, we concluded that MSCs-derived HIF-1α-EVs activated YTHDF1-mediated protective autophagy to promote pancreatic ß cell survival under hypoxic conditions, and HIF-1α-EVs could be used as candidate treatment strategy to increase the success rate of islet transplantation.

Investigation on prevalence and risk factors associated with genitourinary syndrome of menopause in middle-aged and older women in Beijing community: a cross sectional study.

BACKGROUND: Genitourinary syndrome of menopause (GSM) comprises genital symptoms (dryness, burning, itching, irritation, bleeding), sexual symptoms (dyspareunia and other sexual dysfunctions) and urinary symptoms (dysuria, frequency, urgency, recurrent urinary infections) associated with menopause. To avoid invasive testing and painful physical examinations, validated questionaries, which can assess the prevalence and risk factors associated with symptoms of GSM. We aimed to investigate the prevalence and risk factors associated with GSM in middle-aged and older women in the communities of Beijing, China. METHODS: A cross-sectional, questionnaire study was performed among 35-70 years old Chinese woman. Vaginal health index score and urinary distress inventory (UDI-6) was used to evaluate vulvovaginal atrophy (VVA) and urinary incontinence (UI). Stages of pelvic organ prolapse (POP) was measured during gynecological examination with POP-Q system. Mean ± standard deviation (SD) and proportion/percentages were used to summarize continuous and categorial variables respectively. The Bonferroni method was used to adjust for multiple comparisons. RESULTS: A total of 2702/3000 participants completed the questionnaire survey. The mean ± SD age of participants was 53.7 ± 7.0 years and prevalence of VVA among participants was 34.8% (941/2702). In UDI-6 questionnaires total 47.5% (1284/2702) participants reported experiencing urinary incontinence (UI). Further, POP was highly prevalent in anterior vaginal wall 38.9% (1050/2702) followed by posterior vaginal wall 25.3% (683/2702) and uterine 22.2% (599/2702). Besides, multiple logistic regression analysis inferred older age (45-54 years [OR (95% CI): 3.38 (2.03, 5.64)]; 55-64 years [OR (95% CI): 8.63 (5.09, 14.64)]), menopause [OR (95% CI): 2.20 (1.71, 2.85)] and Faecal Inconsistence (FI) [OR (95% CI): 1.31(1.00, 1.72)] as independent risk factors for VVA. CONCLUSIONS: Our study evidenced that GSM is prevalent in old age Chinese women. GSM is related with UI, POP and VVA. Further older age, menopause and FI were risk factors associated with VVA. Our findings could help health care personnel to get a comprehensive overview of factors associated with VVA and urinal distress, which may facilitate early detection and prevention of GSM.

One-pot synthesis of carboxymethyl-dextran coated iron oxide nanoparticles (CION) for preclinical fMRI and MRA applications.

Superparamagnetic iron-oxide nanoparticles are robust contrast agents for magnetic resonance imaging (MRI) used for sensitive structural and functional mapping of the cerebral blood volume (CBV) when administered intravenously. To date, many CBV-MRI studies are conducted with Feraheme, manufactured for the clinical treatment of iron-deficiency. Unfortunately, Feraheme is currently not available outside the United States due to commercial and regulatory constraints, making CBV-MRI methods either inaccessible or very costly to achieve. To address this barrier, we developed a simple, one-pot recipe to synthesize Carboxymethyl-dextran coated Iron Oxide Nanoparticles, namely, "CION", suitable for preclinical CBV-MRI applications. Here we disseminate a step-by-step instruction of our one-pot synthesis protocol, which allows CION to be produced in laboratories with minimal cost. We also characterized different CION-conjugations by manipulating polymer to metal stoichiometric ratio in terms of their size, surface chemistry, and chemical composition, and shifts in MR relaxivity and pharmacokinetics. We performed several proof-of-concept experiments in vivo, demonstrating the utility of CION for functional and structural MRI applications, including hypercapnic CO2 challenge, visual stimulation, targeted optogenetic stimulation, and microangiography. We also present evidence that CION can serve as a cross-modality research platform by showing concurrent in vivo optical and MRI measurement of CBV using fluorescent-labeled CION. The simplicity and cost-effectiveness of our one-pot synthesis method should allow researchers to reproduce CION and tailor the relaxivity and pharmacokinetics according to their imaging needs. It is our hope that this work makes CBV-MRI more openly available and affordable for a variety of research applications.

Glyap1 regulates pneumocandin B0 synthesis by controlling the intracellular redox balance in Glarea lozoyensis.

Pneumocandin B0, the precursor of the antifungal drug caspofungin, is a lipohexapeptide produced by the fungus Glarea lozoyensis. Oxidative stress and the resulting production of reactive oxygen species (ROS) are known to be involved in the regulation of pneumocandin B0 biosynthesis. In this study, the Glyap1 gene of Glarea lozoyensis, a homologue of the yeast redox regulator YAP1, was knocked out. The intracellular ROS levels of the resulting ΔGlyap1 strain were higher than in the wild-type strain, which was caused by the downregulated expression of superoxide dismutase (SOD) and catalase (CAT). Compared with the wild-type strain, ΔGlyap1 exhibited an oxidative phenotype throughout its life cycle, which resulted in significantly higher pneumocandin B0 production per unit biomass. In addition, ΔGlyap1 showed growth inhibition and decreased pneumocandin B0 production in the presence of CCl4, which leads to strong oxidative stress. To overcome the strain's sensitivity, a three-stage antioxidant addition strategy was developed. This approach significantly improved the growth of ΔGlyap1 while maintaining a high pneumocandin B0 production per unit biomass, which reached 38.78 mg/g DCW. Notably, this result represents a 50% increase over the wild-type strain. These findings provide new insights into the regulatory mechanisms that control pneumocandin B0 production under oxidative stress, which may be applied to improve the production of other secondary metabolites. KEY POINTS: • Glyap1 is involved in expression of redox and pneumocandin B0 synthesis-related genes. • Addition of a three-stage antioxidant alleviated the sensitivity of ΔGlyap1 strain. • The yield of pneumocandin B0 per unit biomass of ΔGlyap1 strain was 38.78 mg/g DCW.

Synergistic activation of persulfate by natural chalcocite and ferrous ions by promoting the cycling of Fe3+/Fe2+ couple for degradation of organic pollutants.

Natural chalcocite (NCC) was chosen as a co-catalyst for activation of persulfate (PS) to degrade organic contaminants in this study. A synergistic effect between NCC and ferrous ions (Fe2+) was found in catalyzing PS for degradation of orange G (OG). The main role of NCC in the NCC/Fe2+/PS system was to facilitate Fe3+ reduction back to Fe2+ and thus improve the stoichiometric efficiency of PS. The results of scavenging experiments and electron paramagnetic resonance tests proved that both sulfate and hydroxyl radicals were the primary reactive oxidants in the NCC/Fe2+/PS system. Twelve potential intermediate products of OG were identified, and the degradation pathway was proposed. Experiment parameters, such as NCC dose, Fe2+ concentration, initial pH, and the presence of anions (H2PO4‒ and Cl‒), all had important impacts on OG degradation. NCC had good reusability in synergistic activation of PS with Fe2+ for OG degradation for five cycles. This study demonstrated a natural sulfide mineral as an efficient co-catalyst towards PS activation for destruction of organic contaminants in water.

Single molecule kinetics uncover roles for E. coli RecQ DNA helicase domains and interaction with SSB.

Most RecQ DNA helicases share a conserved domain arrangement that mediates their activities in genomic stability. This arrangement comprises a helicase motor domain, a RecQ C-terminal (RecQ-C) region including a winged-helix (WH) domain, and a 'Helicase and RNase D C-terminal' (HRDC) domain. Single-molecule real-time translocation and DNA unwinding by full-length Escherichia coli RecQ and variants lacking either the HRDC or both the WH and HRDC domains was analyzed. RecQ operated under two interconvertible kinetic modes, 'slow' and 'normal', as it unwound duplex DNA and translocated on single-stranded (ss) DNA. Consistent with a crystal structure of bacterial RecQ bound to ssDNA by base stacking, abasic sites blocked RecQ unwinding. Removal of the HRDC domain eliminates the slow mode while preserving the normal mode of activity. Unexpectedly, a RecQ variant lacking both the WH and HRDC domains retains weak helicase activity. The inclusion of E. coli ssDNA-binding protein (SSB) induces a third 'fast' unwinding mode four times faster than the normal RecQ mode and enhances the overall helicase activity (affinity, rate, and processivity). SSB stimulation was, furthermore, observed in the RecQ deletion variants, including the variant missing the WH domain. Our results support a model in which RecQ and SSB have multiple interacting modes.

Oxidative degradation of Orange G in aqueous solution by persulfate activated with pyrite.

Orange G (OG), a typical azo dye in textile wastewaters, has been the subject of intense investigations. This study investigated oxidative degradation of OG in aqueous solution by persulfate (PS) activated with pyrite. A complete destruction of OG was achieved within 60 min in the pyrite/PS system. Lower solution pH, smaller pyrite particles and higher pyrite dosage was beneficial for OG degradation. Higher PS concentration was also in favour of OG degradation, but excess PS would decrease the removal efficiency of OG. The addition of HCO3 - and H2PO4 - but Cl- had inhibitory effects on the destruction of OG. The results of quenching experiments and electron paramagnetic resonance tests proved that SO4 •- and •OH were the dominant reactive species responsible for OG degradation in the pyrite/PS system. The azo bond, naphthalene ring and benzene ring of OG were all destroyed by the generated reactive species. The mineralization rate of OG reached 34.4% after 60 min of reaction. This work will provide information for understanding azo dye degradation by pyrite activated PS.

RMLNet-A Reliable Wireless Network for a Multiarea TDOA-Based Localization System.

Ultrawideband (UWB) wireless communication is a promising spread-spectrum technology for accurate localization among devices characterized by a low transmission power, a high rate and immunity to multipath propagation. The accurately of the clock synchronization algorithm and the time-difference-of-arrival (TDOA) localization algorithm provide precise position information of mobile nodes with centimeter-level accuracy for the UWB localization system. However, the reliability of target node localization for multi-area localization remains a subject of research. Especially for dynamic and harsh indoor environments, an effective scheme among competing target nodes for localization due to the scarcity of radio resources remains a challenge. In this paper, we present RMLNet, an approach focus on the medium access control (MAC) layer, which guarantees general localization application reliability on multi-area localization. Specifically, the design requires specific and optimized solutions for managing and coordinating multiple anchor nodes. In addition, an approach for target area determination is proposed, which can approximately determine the region of the target node by the received signal strength indication (RSSI), to support RMLNet. Furthermore, we implement the system to estimate the localization of the target node and evaluate its performance in practice. Experiments and simulations show that RMLNet can achieve localization application reliability multi-area localization with a better localization performance of competing target nodes.

Control of Protein Activity and Gene Expression by Cyclofen-OH Uncaging.

The use of light to control the expression of genes and the activity of proteins is a rapidly expanding field. Whereas many of these approaches use fusion between a light-activable protein and the protein of interest to control the activity of the latter, it is also possible to control the activity of a protein by uncaging a specific ligand. In that context, controlling the activation of a protein fused to the modified estrogen receptor (ERT) by uncaging its ligand cyclofen-OH has emerged as a generic and versatile method to control the activation of proteins quantitatively, quickly, and locally in a live organism. We present that approach and its uses in a variety of physiological contexts.

Phylogenetic analyses with four new Cretaceous bristletails reveal inter-relationships of Archaeognatha and Gondwana origin of Meinertellidae.

Based on fifteen Archaeognatha (=Microcoryphia) specimens from Myanmar (Burmese) amber, including males, females and immatures, two new genera and four species, Cretaceomachilis longa sp.n., Unimeinertellus abundus gen. et sp.n., U. bellus sp.n. and Nullmeinertellus wenxuani gen. et sp.n., are described. Phylogenetic analyses of taxa in Archaeognatha were conducted using Maximum parsimony and Bayesian inference based on morphological characters and DNA sequence data. Our results confirm the phylogenetic position of the new genera, clarify the monophyly of Meinertellidae and indicate that the 'paleo-types' excluding Ditrigoniophthalmus are nested within the Machilidae group, but suggest that the three subfamilies within Machilidae may be artificial. The diversity of meinertellids with derived characters found from the Cretaceous indicate that the divergence time of Machilidae and Meinertellidae is much earlier than the Cretaceous. We propose the possibility that Meinertellidae might have originated on Gondwana.

Single molecule studies of helicases with magnetic tweezers.

Helicases are a broad family of enzymes that perform crucial functions in DNA replication and in the maintenance of DNA and RNA integrity. A detailed mechanical study of helicases on DNA and RNA is possible using single molecule manipulation methods. Among those, magnetic tweezers (or traps) present a convenient, moderate throughput assay (tens of enzymes can be monitored simultaneously) that allow for high resolution (single base-pair) studies of these enzymes in various conditions and on various substrates (double and single stranded DNA and RNA). Here we discuss various implementation of the basic assay relevant for these studies.

Detection of DNA methyltransferase activity using allosteric molecular beacons.

Abnormal DNA methylation patterns caused by altered DNA methyltransferase (MTase) activity are closely associated with cancer. Herein, using DNA adenine methylation methyltransferase (Dam MTase) as a model analyte, we designed an allosteric molecular beacon (aMB) for sensitive detection of Dam MTase activity. When the specific site in an aMB is methylated by Dam MTase, the probe can be cut by the restriction nuclease DpnI to release a fluorophore labeled aptamer specific for streptavidin (SA) which will bind to SA beads to generate highly fluorescent beads for easy signal readout by a microscope or flow cytometer. However, aMBs maintain a hairpin structure without the binding ability to SA beads in the absence of Dam MTase, leading to weakly fluorescent SA beads. Unlike the existing signal amplified assays, our method is simpler and more convenient. The high performance of the aptamer and the easy bead separation process make this probe superior to other methods for the detection of MTase in complex biological systems. Overall, the proposed method with a detection limit of 0.57 U mL(-1) for Dam MTase shows great potential for further applications in the detection of other MTases, screening of MTase inhibitors, and early diagnosis of cancer.

AZD2171, a pan-VEGF receptor tyrosine kinase inhibitor, normalizes tumor vasculature and alleviates edema in glioblastoma patients.

Using MRI techniques, we show here that normalization of tumor vessels in recurrent glioblastoma patients by daily administration of AZD2171-an oral tyrosine kinase inhibitor of VEGF receptors-has rapid onset, is prolonged but reversible, and has the significant clinical benefit of alleviating edema. Reversal of normalization began by 28 days, though some features persisted for as long as four months. Basic FGF, SDF1alpha, and viable circulating endothelial cells (CECs) increased when tumors escaped treatment, and circulating progenitor cells (CPCs) increased when tumors progressed after drug interruption. Our study provides insight into different mechanisms of action of this class of drugs in recurrent glioblastoma patients and suggests that the timing of combination therapy may be critical for optimizing activity against this tumor.

How does exotic Spartina alterniflora affect the contribution of iron-bound organic carbon to soil organic carbon in salt marshes?

Iron-bound organic carbon (OC-FeR) is important for the stability of soil organic carbon (SOC) in salt marshes, and the Spartina alterniflora invasion reshaped local salt marshes and changed the SOC pool. To evaluate the effects of S. alterniflora invasion on the contribution of OC-FeR to SOC, we determined the OC-FeR content and soil characteristics in the 0-50 cm soil profile along the vegetation sequence, including mudflats (MF), S. alterniflora marshes established in 2003 (SA03) and 1989 (SA89), the ecotone of S. alterniflora and Phragmites australis (SE), S. salsa marsh (SS), and P. australis marsh (PA). The SOC content was 6.55-17.5 mg g-1 in the S. alterniflora marshes. Reactive iron oxides (Fed, Feo, Fep) accumulated significantly in the S. alterniflora and P. australis salt marshes. PA and S. alterniflora marshes had higher DOC contents of 0.28-0.77 mg g-1. The OC-FeR content in the 0-50 cm soil profile in these ecosystems ranged from 0.3 to 3.29 mg g-1, with a contribution to the SOC content (fOC-FeR) of approximately 11 %, which was highest in SA03 (16.3 % ~ 18.8 %), followed by SA89, SE, and PA. In addition, the molar ratios of OC-FeR to Fed were <1, indicating that the iron oxides were associated with SOC through sorption more than coprecipitation. According to the structural equation model, SOC, DOC and iron oxides were the direct driving factors of OC-FeR formation, while the vegetation zone indirectly functioned by regulating organic C inputs, iron oxide formation, and pH. This study suggested that S. alterniflora invasion promotes iron-bound organic carbon accumulation by increasing organic C inputs and regulating iron oxide formation in salt marshes, but such promotion will degenerate with development duration.