Toe stimulation improves tactile perception of the genitals.

The human body is represented in a topographic pattern in the primary somatosensory cortex (S1), and genital representation is displaced below the toe representation. However, the relationship between the representation of the genitals and toe in S1 remains unclear. In this study, tactile stimulation was applied to the big toe in healthy subjects to observe changes in tactile acuity in the unstimulated genital area, abdomen, and metacarpal dorsal. Then tactile stimulation was applied to the right abdomen and metacarpal dorsal to observe changes in tactile acuity in bilateral genitals. The results revealed that tactile stimulation of the big toe led to a reduction in the 2-point discrimination threshold (2PDT) not only in the stimulated big toe but also in the bilateral unstimulated genitals, whereas the bilateral abdomen and metacarpal dorsal threshold remained unchanged. On the other hand, tactile stimulation of the abdomen and metacarpal dorsal did not elicit 2-point discrimination threshold changes in the bilateral genitals. Cortical and subcortical mechanisms have been proposed to account for the findings. One explanation involves the intracortical interaction between 2 adjacent representations. Another possible explanation is that the information content of a specific body part is broadly distributed across the S1. Moreover, exploring the links between human behaviors and changes in the cerebral cortex is of significant importance.

Hydrophobic Multilayered PEG@PAN/MXene/PVDF@SiO2 Composite Film with Excellent Thermal Management and Electromagnetic Interference Shielding for Electronic Devices.

With the rapid development of electronic industry, it's pressing to develop multifunctional electromagnetic interference (EMI) shielding materials to ensure the stable operation of electronic devices. Herein, multilayered flexible PEG@PAN/MXene (Ti3C2Tx)/PVDF@SiO2 (PMF) composite film has been constructed from the level of microstructure design via coaxial electrospinning, coating spraying, and uniaxial electrospinning strategies. Benefiting from the effective encapsulation for PEG and high conductivity of MXene coating, PEG@PAN/MXene composite film with MXene coating loading density of 0.70 mg cm-2 exhibits high thermal energy storage density of 120.77 J g-1 and great EMI shielding performance (EMI SE of 34.409 dB and SSE of 49.086 dB cm3 g-1) in X-band (8-12 GHz). Therefore, this advanced composite film can not only help electronic devices prevent the influence of electromagnetic pollution in the X-band but also play an important role in electronic device thermal management. Additionally, the deposition of nano PVDF@SiO2 fibers (289 ± 128 nm) endowed the PMF composite film with great hydrophobic properties (water contact angle of 126.5°) to ensure the stable working of hydrophilic MXene coating, thereby breaks the limitation of humid application environments. The finding paves a new way for the development of novel multifunctional EMI shielding composite films for electronic devices.

Fiber Bragg grating sensing system for temperature measurements based on optically injected DFB-LD with an OEO loop.

A novel fiber Bragg grating (FBG) sensing system, based on an optically injected distributed feedback laser diode (DFB-LD) with an optoelectronic oscillating (OEO) loop, is proposed and experimentally demonstrated for temperature measurements with high and tunable sensitivity. The FBG sensor device works as an edge filter to adjust the optical power of the injected beam in response to temperature variations. The optically injected DFB-LD works at Period-one (P1) oscillating state, and the central wavelength of the oscillating mode of the DFB-LD can be tuned by the variable power of the injected beam. Furthermore, an OEO loop is implemented to improve the signal quality of the generated P1 microwave signal. Hence, the sensing parameter of temperature is converted to the frequency variation of the generated P1 microwave signal in the proposed sensing system. In the proof-of-concept experiment, a series of P1 microwave signals are generated while different temperatures are applied to the FBG sensor. The sensitivity of the proposed FBG sensing system for temperature measurements can be tuned from 0.44322 GHz/°C to 1.25952 GHz/°C. The stability and repeatability experiments are also performed, demonstrating the high measurement accuracy (0.0629°C) and low error of the system. The proposed FBG-based sensing and interrogation system exhibits high sensitivity, large tunability, good linearity, and flexible sensing generality.

Enhancing Targeted Photodynamic Therapy: Star-Shaped Glycopolymeric Photosensitizers for Improved Selectivity and Efficacy.

Targeted photodynamic therapy (PDT) offers advantages over nontargeted approaches, including improved selectivity, efficacy, and reduced side effects. This study developed star-shaped glycopolymeric photosensitizers using porphyrin-based initiators via ATRP. Incorporating a porphyrin core gave the polymers fluorescence and ROS generation, while adding fructose improved solubility and targeting capabilities. The photosensitizers had high light absorption, singlet oxygen production, specificity, low dark toxicity, and biocompatibility. The glycopolymers with longer sugar arms and higher density showed better uptake on MCF-7 and MDA-MB-468 cells compared to HeLa cells, indicating enhanced targeting capabilities. Inhibition of endocytosis confirmed the importance of the GLUT5 receptor. The resulting polymers exhibited good cytocompatibility under dark conditions and satisfactory PDT under light irradiation. Interestingly, the polymers containing fructose have a GLUT5-dependent elimination effect on the MCF-7 and MDA-MB-468 cells. The intracellular ROS production followed a similar pattern, indicating that the fructose polymer exhibits specific targeting toward cells with GLUT5 receptors.

Enhancement of Motor Learning and Corticospinal Excitability: The Role of Electroacupuncture and Motor Training in Healthy Volunteers.

BACKGROUND This study embarked on an innovative exploration to elucidate the effects of integrating electroacupuncture (EA) with motor training (MT) on enhancing corticospinal excitability and motor learning. Central to this investigation is the interplay between homeostatic and non-homeostatic metaplasticity processes, providing insights into how these combined interventions may influence neural plasticity and motor skill acquisition. MATERIAL AND METHODS The investigation enrolled 20 healthy volunteers, subjecting them to 4 distinct interventions to parse out the individual and combined effects of EA and MT. These interventions were EA alone, MT alone, EA-priming followed by MT, and MT-priming followed by EA. The assessment of changes in primary motor cortex (M1) excitability was conducted through motor-evoked potentials (MEPs), while the grooved pegboard test (GPT) was used to evaluate alterations in motor performance. RESULTS The findings revealed that EA and MT independently contributed to enhanced M1 excitability and motor performance. However, the additional priming with EA or MT did not yield further modulation in MEPs amplitudes. Notably, EA-priming was associated with improved GPT completion times, underscoring its potential in facilitating motor learning. CONCLUSIONS The study underscores that while EA and MT individually augment motor cortex excitability and performance, their synergistic application does not further enhance or inhibit cortical excitability. This points to the involvement of non-homeostatic metaplasticity mechanisms. Nonetheless, EA emerges as a critical tool in preventing M1 overstimulation, thereby continuously fostering motor learning. The findings call for further research into the strategic application of EA, whether in isolation or with MT, within clinical settings to optimize rehabilitation outcomes.

Effect of suspended particulate matter on physiological, biochemical and photosynthetic characteristics of Chlorella pyrenoidosa in the Jinjiang Estuary (Fujian, China).

Suspended particulate matter (SPM), an important component of the natural water environment, can act as a carrier of many pollutants that affect aquatic organisms. In the present study, the effect of SPM obtained from Jinjiang Estuary on the physiological, biochemical, and photosynthetic properties of typical freshwater algae (Chlorella pyrenoidosa) was investigated. The results showed that under different concentrations of SPM treatment, the superoxide dismutase (SOD), catalase (CAT) activities, and malondialdehyde (MDA) content of C. pyrenoidosa increased, but the soluble protein content decreased. SPM with different particle sizes had less effect on SOD of C. pyrenoidosa, but showed a promoting effect on CAT and MDA as well as soluble protein content. In terms of photosynthetic activity, high concentrations (70, 90 mg/L) and small particle sizes (0-75, 75-120 µm) of SPM had a greater effect on the chlorophyll a content of C. pyrenoidosa. In addition, different concentrations of SPM had no significant effect on the potential photosynthetic activity of PS II (Fv/F0) and the maximum quantum yield of PS II (Fv/Fm), but the inhibition of the initial slope (alpha), the maximum photosynthetic rate (ETRmax) and the semi-light saturation point (Ik) increased with the increase of SPM concentration. Fv/F0, ETRmax, and Ik of C. pyrenoidosa showed some degree of recovery after inhibition in the presence of SPM of different particle sizes.

Copper-based photocatalysts with natural organic ligands for efficient removal of tetracycline under visible light.

The excessive use of broad-spectrum antibiotics, such as tetracycline, presents a significant challenge to human survival and development. Oxygen vacancies (OVs) metal-organic framework (MOF) materials were synthesized using natural organic acids (L-malic acid, L-aspartic acid, and L-asparagine) with similar structures but different charge densities, along with copper as the metal linking agent. The presence of oxygen vacancies in the catalyst provides abundant active sites for photocatalytic reactions. The employment of flexible straight-chain organic ligands devoid of rigid polycyclic rings, combined with the incorporation of different substituents to induce variations in charge density, the resulting catalysts exhibit distinct photocatalytic activities under visible light. Density functional theory calculations confirm that L-asparagine exhibits the largest electron density difference, and the Cu-based MOF (Cu-ASU) synthesized as an organic ligand exhibits the highest photocatalytic activity under visible light excitation. The catalyst displayed remarkable photocatalytic activity against tetracycline antibiotics under identical conditions (with removal rates of 93.5 % for tetracycline, 81.4 % for terramycin, and 95.6 % for chloramphenicol hydrochloride). This provides a novel approach for the design and synthesis of photocatalysts for the removal of antibiotics from water.

White matter microstructural disruption in minimal hepatic encephalopathy: a neurite orientation dispersion and density imaging (NODDI) study.

PURPOSE: To evaluate the ability of neurite orientation dispersion and density imaging (NODDI) for detecting white matter (WM) microstructural abnormalities in minimal hepatic encephalopathy (MHE). METHODS: Diffusion-weighted images, enabling the estimation of NODDI and diffusion tensor imaging (DTI) parameters, were acquired from 20 healthy controls (HC), 22 cirrhotic patients without MHE (NHE), and 15 cirrhotic patients with MHE. Tract-based spatial statistics were used to determine differences in DTI (including fractional anisotropy [FA] and mean/axial/radial diffusivity [MD/AD/RD]) and NODDI parameters (including neurite density index [NDI], orientation dispersion index [ODI], and isotropic volume fraction [ISO]). Voxel-wise analyses of correlations between diffusion parameters and neurocognitive performance determined by Psychometric Hepatic Encephalopathy Score (PHES) were completed. RESULTS: MHE patients had extensive NDI reduction and rare ODI reduction, primarily involving the genu and body of corpus callosum and the bilateral frontal lobe, corona radiata, external capsule, anterior limb of internal capsule, temporal lobe, posterior thalamic radiation, and brainstem. The extent of NDI and ODI reduction expanded from NHE to MHE. In both MHE and NHE groups, the extent of NDI change was quite larger than that of FA change. No significant intergroup difference in ISO/MD/AD/RD was observed. Tissue specificity afforded by NODDI revealed the underpinning of FA reduction in MHE. The NDI in left frontal lobe was significantly correlated with PHES. CONCLUSION: MHE is characterized by diffuse WM microstructural impairment (especially neurite density reduction). NODDI can improve the detection of WM microstructural impairments in MHE and provides more precise information about MHE-related pathology than DTI.

Synthesis and Cytotoxicity Evaluation of Betulin Cycloolefin Derivatives by Ruthenium-Catalyzed Ring-Closing Metathesis.

The combination of ring-closing metathesis with betulin enables the design and synthesis of novel biomolecules representing a library of triterpenoid derivatives for potential pharmacological research. In this work, cyclic olefin betulin derivatives were attempted to be prepared by the combination of ring-closing metathesis with betulin. Dicyclohexyl carbodiimide coupling reaction allowed the transformation of betulin into two types of linear olefin derivatives that have different methylene spacer lengths between the olefin and ester groups. Subsequently, betulin-based cycloolefins were synthesized by ring-closing metathesis using Grubbs first-generation catalyst. The influence of different parameters including solvents, temperature, catalysts, and catalyst loading on ring-closing metathesis was investigated. Cytotoxicity results indicated that these betulin-based olefin derivatives, derived from renewable bioresources, have potential applications in the biomedical field.

Pan-Cancer Analysis of the Cuproptosis-Related Gene DLD.

Background: Cancer affects millions of people each year and imposes a huge economic and social burden worldwide. Cuproptosis is a recently discovered novel mode of cell death. The exact function of the cuproptosis-related gene dihydrolipoamide dehydrogenase (DLD) and its role in pan-cancer is unknown. Methods: Data were retrieved from the GTEx, TCGA, and multiple online websites. These data were used to assess the expression, prognosis, and diagnostic value of DLD in various tumors. The relationship of DLD with immune microenvironment immunomodulators, immune checkpoints, tumor mutational load (TMB), microsatellite instability (MSI), and oncology drug sensitivity was explored by correlation analysis. Results: The mRNA and protein expression of DLD differs in most cancers. Survival analysis showed that DLD was associated with prognosis with KIRC, KIRP, KICH, and UCS. DLD had a strong diagnostic value in KIRC, GBM, PAAD, and LGG (AUC > 0.9). DLD promoter methylation affects the aberrant expression of LIHC, LUSC, PAAD, READ, and THCA. DLD was negatively correlated with stromal score, immune score, and ESTIMATE score in UCEC, TGCT, LUSC, and SARC. In UCS, resting memory CD4 T cells and activated NK cells were significantly correlated with DLD expression. Significant correlations were also observed between DLD expression and immunomodulators, immune checkpoints, TMB, and MSI in various cancers. Importantly, we also identified a number of potential drugs that may target DLD. Conclusion: DLD expression is associated with a variety of tumor prognoses and plays an integral role in tumorigenesis, tumor metabolism, and immunity.

Analysis of factors influencing the determination of indications for allergen-specific immunotherapy.

OBJECTIVE: To develop a questionnaire and a scoring system for evaluating physicians' knowledge of allergen immunotherapy (AIT). METHODS: Questionnaire was designed using the Questionnaire Star tool. A total of 1024 physicians were assessed, and based on the score divided into accurate judgment and inaccurate judgment groups. Statistical analysis was done, and counting data were expressed as frequencies and percentage values. Chi-square test and multi-factor logistic analysis were used to determine influencing factors on the indications for AIT. RESULTS: Physician's age, grade of the hospital, and pediatric specialty influenced the accurate judgment of AIT indication after adjustment for independent variables (P < 0.05). In all, 80.5% physicians exercised accurate assessment for allergic rhinitis. Allergic conjunctivitis was judged accurately by 47.0% physicians. Bronchial asthma was judged accurately by 71.0% physicians, and atopic dermatitis by 61.3% physicians, with a higher accuracy rate for pediatricians than nonpediatricians for all the mentioned conditions (P < 0.05). There was no significant difference in the accuracy of judgment between pediatricians and non-pediatricians in terms of AIT for food allergy and dust mite sensitization (P > 0.05). CONCLUSION: The results of our study demonstrated a high accuracy judgment rate among clinicians for rhinitis, asthma, and dermatitis, and a low accuracy rate for desensitization of healthy people with allergic conjunctivitis, food allergies, and allergen sensitization.

A comparison of special intrauterine balloons and intrauterine contraceptive devices in the treatment of intrauterine adhesions.

PURPOSE: This study aimed to compare the efficacy of a special kind of intrauterine balloon (IUB) and that of an intrauterine contraception device (IUD) for patients with intrauterine adhesions (IUAs) after transcervical resection of adhesion (TCRA). METHODS: In this retrospective cohort study, after TCRA, 31 patients received a special IUB, and 38 patients received an IUD. The Fisher exact test, logistic regression method, Kaplan-Meier method and Cox proportional hazards regression model were used for statistical analysis. A two-sided value of P < 0.05 was considered statistically significant. RESULTS: The readhesion rate significantly differed between the IUB group and IUD group, at 15.39% and 54.06%, respectively (P = 0.002). For recurrent moderate IUA, patients in the IUB group had lower scores than patients in the IUD group (P = 0.035). There was a significant difference in the intrauterine pregnancy rate of IUA patients in the IUB group and IUD group after treatment, with rates of 55.56% and 14.29%, respectively (P = 0.015). CONCLUSION: Patients in the special IUB group had better outcomes than those in the IUD group, which has a certain guiding significance for clinical work.

Five New Phenylpropanoyl Phloroglucinol Derivatives from Leptospermum scoparium.

Leptosperols C-G (1-5), five new phenylpropanoyl phloroglucinol derivatives were isolated from the leaves of Leptospermum scoparium. Compounds 1-3 are phenylpropanoyl phloroglucinol-sesquiterpene adducts with new carbon skeletons. Their structures with absolute configurations were elucidated by detailed spectroscopic analyses, single-crystal X-ray diffraction, and electronic circular dichroism (ECD) calculation. Compounds 2 and 3 exhibited moderate anti-inflammatory activity in zebrafish acute inflammatory models.

Altered dynamic brain activity and its association with memory decline after night shift-related sleep deprivation in nurses.

AIMS AND OBJECTIVES: To investigate, for the first time, aberrant time-varying local brain activity in nurses following night shift-related sleep deprivation (SD) and its association with memory decline. BACKGROUND: Prior studies have elucidated alterations in static local brain activity resulting from SD in the occupations outside medical profession. DESIGN: A longitudinal study followed the STROBE recommendations. METHODS: Twenty female nurses underwent resting-state functional magnetic resonance imaging and memory function assessment (by Complex Figure Test (CFT) and the California Verbal Learning Test, Second Edition (CVLT-II)) twice, once in a rested wakefulness (RW) state and another after SD. By combining the sliding-window approach and amplitude of low-frequency fluctuation (ALFF) analysis, the dynamic ALFF (dALFF) variability was calculated to reflect the characteristics of dynamic local brain activity. RESULTS: Poor performance on the CFT and CVLT-II was observed in nurses with night shift-related SD. Reduced dALFF variability was found in a set of cognition-related brain regions (including the medial/middle/superior frontal gyrus, anterior/posterior cingulate gyrus, precuneus, angular gyrus, orbitofrontal and subgenual areas, and posterior cerebellum lobe), while increased dALFF variability was observed in the somatosensory-related, visual and auditory regions. SD-related dALFF variability alterations correlated with changes in subjects' performance on the CFT and CVLT-II. CONCLUSIONS: Night shift-related SD disturbed dynamic brain activity in high cognitive regions and induced compensatory reactions in primary perceptual cortex. Identifying dALFF variability abnormalities may broaden our understanding of neural substrates underlying SD-related cognitive alterations, especially memory dysfunction. RELEVANCE TO CLINICAL PRACTICE: Night shift-related SD is as an important occupational hazard affecting brain function in nurses. The effective countermeasure addressing the adverse outcomes of SD should be advocated for nurses. PATIENT OR PUBLIC CONTRIBUTION: Patients or public were not involved in the design and implementation of the study or the analysis and interpretation of the data.

Promoting effect of Fe3+ on gentamicin resistance in Escherichia coli.

Kinds of antibiotics are used to prevent and control bacteria infections, unfortunately, the overuse and misuse of antibiotic have promoted the emergence and spread of antibiotic-resistant bacteria. Therefore, understanding the mechanism of antibiotic resistance is very important. This study explores the combined effection of metal ions and antibiotic to the drug resistance of Escherichia coli. Our results found that the minimum inhibitory concentration (MIC) increased as the ammonium ferric citrate concentration increased, especially for gentamicin antibiotic. When the Fe3+ concentration reached 300 µM, the survival of E. coli was stably restored with the increased gentamicin concentration. Exogenous Fe3+ could decrease intracellular gentamicin concentration. On the other hand, Fe3+ treatment together with gentamicin could reduce reactive oxygen species (ROS) production, characterized by decreased levels of NADH and ATP. Furthermore, ROS-scavenging enzymes of superoxide dismutase (SOD) and catalase (CAT) were up-regulated and H2O2 plus gentamicin-mediated killing was restored by Fe3+. These results may have significant implications in understanding bacterial antibiotic-resistant mechanisms based on the external Fe3+ concentration.

A bidirectional Hopf bifurcation analysis of Parkinson's oscillation in a simplified basal ganglia model.

In this paper, we study the parkinson oscillation mechanism in a computational model by bifurcation analysis and numerical simulation. Oscillatory activities can be induced by abnormal coupling weights and delays. The bidirectional Hopf bifurcation phenomena are found in simulations, which can uniformly explain the oscillation mechanism in this model. The Hopf1 represents the transition between the low firing rate stable state (SS) and oscillation state (OS), the Hopf2 represents the transition between the high firing rate stable state (HSS) and the OS, the mechanisms of them are different. The Hopf1 and Hopf2 bifurcations both show that when the state transfers from the stable region to the oscillation region, oscillatory activities originate from the beta frequency band or the gamma frequency band. We find that the changing trends of the frequency (DF) and oscillation amplitude (OSAM) are contrary in many cases. The effect of the delay in inhibitory pathways is greater than that of in excitatory pathways, and appropriate delays improve the discharge activation level (DAL) of the system. In all, we infer that oscillations can be induced by the follow factors: 1. Improvement of the DAL of the globus pallidus externa (GPe); 2. Reduce the DAL of the GPe from the HSS or the discharge saturation state; 3. The GPe can also resonate with the subthalamic nucleus (STN).

Elevated circulating levels of gasdermin D are related to acute myocardial infarction and pyrogptosis.

BACKGROUND: Acute myocardial infarction (AMI) is one of the leading contributors to morbidity and mortality worldwide, with a prevalence of nearly three million people, and more than one million deaths reported in the United States every year. Gasdermin D (GSDMD) is involved in the development of atherosclerosis as a key protein of proptosis. This study was designed to determine the potential relationship of GSDMD with AMI in Chinese patients. METHODS: One hundred patients with AMI and 50 controls were consecutively enrolled in this prospective observational study. GSDMD expression levels and other clinical variables in peripheral blood mononuclear cells (PBMCs) were measured upon admission to the hospital. All patients were followed up for 360 days, and the endpoint was considered the occurrence of major adverse cardiovascular events (MACE). RESULTS: GSDMD expression levels in the PBMCs of patients with AMI were significantly higher than those in the controls. Moreover, our analysis showed that GSDMD was an independent biomarker of AMI and had a promising diagnostic ability for it. Finally, the results suggested that high expression of GSDMD and diabetes increased the risk of MACE after AMI. CONCLUSIONS: This study indicated that the GSDMD expression level in PBMCs was elevated in AMI patients and was closely associated with the pyroptosis of AMI.

Rescue of recombinant canine distemper virus that expresses S1 subunit of SARS-CoV-2 spike protein in vitro.

The coronavirus disease 2019 (COVID-19), as an unprecedented pandemic, has rapidly spread around the globe. Its etiological agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), belongs to the genus Betacoronavirus in the family Coronaviridae. The viral S1 subunit has been demonstrated to have a powerful potential in inducing protective immune responses in vivo. Since April 2020, farmed minks were frequently reported to be infected with the SARS-CoV-2 in different countries. Unfortunately, there has been no available veterinary vaccine as yet. In this study, we used reverse genetics to rescue a recombinant canine distemper virus (CDV) that could express the SARS-CoV-2 S1 subunit in vitro. The S1 subunit sequence was demonstrated to be relatively stable in the genome of recombinant CDV during twenty serial viral passages in cells. However, due to introduction of the S1 subunit sequence into CDV genome, this recombinant CDV grew more slowly than the wild-type strain did. The genomic backbone of recombinant CDV was derived from a virulence-attenuating strain (QN strain). Therefore, if able to induce immune protections in minks from canine distemper and COVID-19 infections, this recombinant would be a potential vaccine candidate for veterinary use.

Dynamics of Soil Microbial N-Cycling Strategies in Response to Cadmium Stress.

Globally increasing trace metal contamination of soils requires a better mechanistic understanding of metal-stress impacts on microbially mediated nutrient cycling. Herein, a 5-month laboratory experiment was employed to assess the effects of cadmium (Cd) on soil microbial N-cycling processes and associated functional gene abundance, with and without urea amendment. In non-N-amended soils, Cd progressively stimulated microbial populations for N acquisition from initial dissolved organic N (DON) to later recalcitrant organic N. The acceleration of N catabolism was synchronously coupled with C catabolism resulting in increased CO2/N2O fluxes and adenosine triphosphate (ATP) contents. The abundance of microbes deemed inefficient in N catabolism was gradually repressed after an initial stimulation period. We posit that enhanced exergonic N processes diminished the need for endergonic activities as a survival strategy for N communities experiencing metal stress. With urea amendment, Cd exhibited an initial stimulation effect on soil nitrification and a later a promotion effect on mineralization, along with an increase in the associated microbial populations. In N-amended soils, Cd accelerated N/C transformation processes, but decreased N2O and CO2 fluxes by 19 and 14%, respectively. This implies that under eutrophic conditions, Cd synchronously altered microbial C/N metabolism from a dominance of catabolic to anabolic processes. These results infer a nutrient-based adjustment of microbial N-cycling strategies to enhance their metal resistance.

Contrasting effects of carbon source recalcitrance on soil phosphorus availability and communities of phosphorus solubilizing microorganisms.

Carbon (C) additions to soil interact through chemical and microbiological processes to cause changes in soil phosphorus (P) availability. However, the response of soil P transformations and relevant microbial communities to C additions having different degrees of recalcitrance remains uncertain. We studied the effects of glucose, hemicellulose and lignin addition on soil P availability, P transformation processes and relevant microbial activity and communities in a P-deficient flooded soil. Lignin significantly increased soil available P concentrations, which was attributed to chemical release of inorganic P and increased alkaline phosphatase activity. Glucose and hemicellulose additions stimulated microbial metabolism of C thereby enhancing microbial demand for P, with increased soil P availability especially in the early incubation period. Glucose or hemicellulose addition changed soil microbial diversity and community composition, leading to enhanced growth and interactions of P solubilizing microorganisms such as Desulfitobacterium, Bacillus and Desulfosporosinus. Our results infer the importance of pH alteration and competitive sorption between PO4 and functional groups of recalcitrant C (e.g., lignin) with Fe/Al (hydr) oxides in regulating soil P availability. Further, the microbial response to labile C additions led to increased P availability in the P-deficient soil. This study provides important mechanistic information to guide microbially-regulated soil P management in agricultural ecosystems.