Low Pi Research Articles

Defense-related callose synthase PMR4 promotes root hair callose deposition and adaptation to phosphate deficiency in Arabidopsis thaliana.

Plants acquire phosphorus (P) primarily as inorganic phosphate (Pi) from the soil. Under Pi deficiency, plants induce an array of physiological and morphological responses, termed phosphate starvation response (PSR), thereby increasing Pi acquisition and use efficiency. However, the mechanisms by which plants adapt to Pi deficiency remain to be elucidated. Here, we report that deposition of a β-1,3-glucan polymer called callose is induced in Arabidopsis thaliana root hairs under Pi deficiency, in a manner independent of PSR-regulating PHR1/PHL1 transcription factors and LPR1/LPR2 ferroxidases. Genetic studies revealed PMR4 (GSL5) callose synthase being required for the callose deposition in Pi-depleted root hairs. Loss of PMR4 also reduces Pi acquisition in shoots and plant growth under low Pi conditions. The defects are not recovered by simultaneous disruption of SID2, mediating defense-associated salicylic acid (SA) biosynthesis, excluding SA defense activation from the cause of the observed pmr4 phenotypes. Grafting experiments and characterization of plants expressing PMR4 specifically in root hair cells suggest that a PMR4 pool in the cell type contributes to shoot growth under Pi deficiency. Our findings thus suggest an important role for PMR4 in plant adaptation to Pi deficiency.

Exploring Enzyme Encapsulation Efficiency in MOFs Using Eco-Friendly Approaches.

The encapsulation of protein enzymes in metal-organic frameworks (MOFs) has been recognized as an effective enzyme immobilization approach. In this study, we demonstrated the influence of enzyme amount and the isoelectric points (pI) of different enzymes on the enzyme loading capacity in both mechanochemical (ball-milling) and water-based approaches. We found that increasing enzyme amounts enhances MOF enzyme loading without compromising activity, while the MOF shell protects encapsulated enzymes from proteinase K degradation through its size-sheltering mechanism. However, an excess of enzymes can hinder the formation of ZIF-90. Moreover, enzymes with low pI values (e. g., catalase, pI 5.4) facilitate encapsulation in MOFs, whereas enzymes with high pI values (e. g., lysozyme, pI 11.35) are more challenging to encapsulate. The simulation results revealed that increasing the enzyme amounts and pI values raises the activation energy necessary for MOF formation. This study highlights the crucial role of enzyme properties in the encapsulation process within MOFs, providing valuable insights for fabricating enzyme-MOF biocomposites for diverse applications, such as protein drug delivery.

Differential Expression of Phosphate Starvation-responsive Genes among Sweetpotato Cultivars during Establishment and Onset of Storage Root Formation

It has been documented that sweetpotato (Ipomoea batatas L.) cultivars vary in morphological and physiological adaptations to low phosphorus (P) availability but knowledge of the underlying molecular mechanisms is largely unknown. The objective of this research was to generate cultivar-specific information about phosphate starvation response (PSR) genes to variations in inorganic phosphate (Pi) availability at the onset of storage root formation among sweetpotato cultivars. Cultivars Bayou Belle (BB), Evangeline (EV), and Orleans (OR) were grown under varying Pi levels: 0 mg·L−1 (low Pi), 15 mg·L−1 (Pi-sufficient), and 31 mg·L−1 (high Pi). Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) analysis of PSR genes IbPHR1, IbSPX1, IbSPX3, IbPHT1;4, IbPHT1;5, and IbNLA was performed at 5 and 10 days after planting (DAP), corresponding to adventitious root system establishment and the onset of storage root formation, respectively. The cultivar BB grown under low Pi showed significantly higher expression of all genes except IbPHR1. The cultivar OR grown in both low and high Pi exhibited upregulation of IbPHR1. On the other hand, EV grown under low Pi revealed no response for all genes investigated. Exposure of BB to high Pi resulted in a decrease in expression for all genes except IbNLA. The cultivar EV grown in high Pi conditions showed increase in expression for IbSPX1, IbPHT1;5, and IbNLA. Expression pattern difference among cultivars relative to Pi levels corroborates field observations showing that BB, EV, and OR have different Pi requirements. The increased activity of BB PSR genes grown under low Pi supports the hypothesis that BB requires low P fertilizer input relative to OR and EV. Results from this study corroborate findings from well-characterized crop species and model systems and pave the way for the development of tools and practices to increase phosphorus use efficiency in sweetpotato.

Unveiling a novel exopolysaccharide produced by Pseudomonas alcaligenes Med1 isolated from a Chilean hot spring as biotechnological additive

Exopolysaccharides (EPSs), a constitutive part of bacterial biofilm, act as a protecting sheath to the extremophilic bacteria and are of high industrial value. In this study, we elucidate a new EPS produced by thermotolerant (growth from 34–44 °C) strain Pseudomonas alcaligenes Med1 from Medano hot spring (39.1 °C surface temperature, pH 7.1) located in the Central Andean Mountains of Chile. Bacterial growth was screened for temperature tolerance (10–60 °C) to confirm the thermotolerance behaviour. Physicochemical properties of the EPS were characterized by different techniques: Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), High-Performance Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). Whole genome of P. alcaligenes Med1 has also been studied in detail to correlate the structural and functional characteristics with genomic insight. The EPS demonstrated amorphous surface roughness composed of evenly distributed macromolecular lumps composed of mainly carbon and oxygen. The monosaccharide analysis has shown the presence of glucose, galactose, and mannose sugars at different ratios. TGA revealed the high thermal stability (315.3 °C) of the polysaccharide. The GPC has shown that Med1 is a low molecular weight polysaccharide (34.8 kDa) with low PI. The 2D-NMR linkage analysis suggests a diverse array of glycosidic bonds within the exopolysaccharide structure. The functional properties of the EPS were evaluated for food industry applications, specifically for antioxidant (DPPH, FRAP an H2O2). Extracted Med1 EPS revealed significant emulsification activity against different food grade vegetative oils (Coconut oil, Corn oil, Canola oil, Avocado oil, Sunflower oil, Olive oil, and Sesame oil). The highest 33.9% flocculation activity was observed with 60 mg L−1 EPS concentration. It showed water-holding (WHC) of 107.6% and oil-holding (OHC) capacity of 110.8%. The functional EPS produced by Pseudomonas alcaligenes Med1 from Central Andean Chilean hot spring of central Chile can be a useful additive for the food-processing industry.

Perfusion index as an early predictor of hypotension during advanced oncothoracic operations (pilot study)

Introduction. Current standards of intraoperative monitoring significantly reduce the response time to a decrease in blood pressure, but do not include methods for predicting changes in hemodynamics to avoid the effects of systemic hypoperfusion.The objective was to evaluate the usefulness of determining the perfusion index for predicting the development of hypotension and its earlier correction during advanced oncothoracic operations.Materials and methods. A prospective open-label observational study was conducted, which included 100 patients who underwent elective oncothoracic surgery. Standard monitoring was established, as well as continuous monitoring of the perfusion index. The perfusion index value was recorded immediately before induction. The patients were divided into 2 groups: in the 1st group (n = 37), patients experienced a decrease in blood pressure, requiring vasopressor support; in the 2nd group (n = 63), no vasopressor support was required.Results. A moderate linear relationship was revealed with a correlation coefficient (r) equal to (–0.68), p < 0.001, and a strong non-linear relationship with a coefficient (ρ) equal to (–0.95), p < 0.001. To identify the relationship model, polynomial regression analysis was performed. A prognostic formula for the use of vasopressors was calculated depending on the preoperative level of perfusion index. At the next stage, a classification tree for analyzing the data array was used. The entire d data array (n = 100) is randomly divided into training (n = 70) and test samples (n = 30). It was revealed that hypotension requiring vasopressor support occurred in patients whose initial perfusion index was ≤ 2.85. ROC analysis determined an AUC of 0.952 (95% CI: 0.888–1.016).Conclusion. A low PI value before induction of anesthesia during advanced oncothoracic operations can be used to monitor the functional activity of the autonomic nervous system and predict intraoperative hypotension. Patients with a baseline PI ≤ 2.85 have a higher risk of developing hypotension during advanced oncothoracic surgery compared with those with a baseline PI ≥ 2.85. The effectiveness of the method in patients with concomitant pathologies has not been tested.

Influence of N- and/or P-restriction on bone metabolism in young goats.

Ruminants can recycle nitrogen (N) and phosphorus (P), which are essential for vital body processes. Reduced N- and P-intake in ruminants is desirable for economic and ecologic reasons. Simultaneous modulation of mineral homoeostasis and bone metabolism occurs in young goats. This study aimed to investigate potential effects of dietary N- and/or P-restriction on molecular changes in bone metabolism. The twenty-eight young male goats were fed a control diet, an N-reduced diet, a P-reduced diet or a combined N- and P-reduced diet for 6-8 weeks. The N-restricted goats had lower plasma Ca concentration and higher plasma osteocalcin (OC) and CrossLaps concentrations. The P-restricted goats had reduced plasma inorganic phosphate (Pi) concentrations and increased plasma Ca concentrations. Due to the initiation of a signalling pathway that inhibits the fibroblast growth factor 23 (FGF23) expression, this was lower with P-restriction. Consequently, lower Pi concentrations were the main factor influencing the reduction in FGF23. The changes in mineral homoeostasis associated with P-restriction led to a reduction in OC, bone mineral content and mineral density. Simultaneously, bone resorption potentially increased with P-restriction as indicated by an increased receptor activator of NF-κB ligand/osteoprotegerin (OPG) ratio and an increase in OPG mRNA expression. Additionally, the increased mRNA expression of the calcitonin receptor during P-restriction points to a higher number of osteoclasts. This study demonstrates an impairment of bone remodelling processes in young goats by N- or P-restriction. With P-restriction, bone mineralisation rate was potentially reduced and bone quality impaired, while with N-restriction, bone remodelling increased.

Recombinant Fibrous Protein Gels as Rheological Modifiers in Skin Ointments.

Rheological modifiers are an important component in the development of skin cream (SC) chassis for personal skin care products (PSCPs). The viscous behavior of a PSCP is critical to its effectiveness where its uniformity and material strength impact its processing, storage, and delivery of active ingredients. Due to the mildly acidic environment of the skin, PSCPs require a SC that will assist in maintaining their material strength at low pHs. We have investigated a coiled-coil protein hydrogel system for the ability to possess pH-responsiveness, where physical cross-linking and material strength is controlled by pH relative to the isoelectric point (pI) of the protein. We recently designed a coiled-coil protein hydrogel variant, Q5, which possesses a relatively low pI that we hypothesized to have improved supramolecular assembly into a hydrogel at acidic conditions. We demonstrate that Q5 can retain a partial solution-to-gel transition at pH 6.0 and acts as a soft hydrogel by rheology. We further tested Q5 to act as a rheological modifier in a standard SC at pH 6.0 and pH 8.0 to test conditions mediated by pH changes in the skin environment. Q5 reveals the ability to uniquely increase material strength at low pH in comparison to a standard rheological modifier like hydroxyethyl cellulose (HEC), suggesting modular protein-based coiled-coil rheological modifiers can be used in PSCPs.

Mapping Age Differences in Brain Energy Metabolites and Metabolic Markers of Cellular Membrane Production and Degradation With 31P Magnetic Resonance Spectroscopy.

Using Phosphorus Magnetic Resonance Spectroscopy (31P MRS), we examined five metabolites associated with brain energy cycle, and cellular membrane production and degradation in 11 brain regions of 48 children (age 6-15), and 80 middle-aged and older adults (age 52-87). Levels of phosphomonoesters (PMEs) and phosphodiesters (PDEs), gamma plus alpha adenosine triphosphate (γαATP), phosphocreatine (PCr) and inorganic phosphate (Pi), were residualized on the total amplitude value. PMEs were greater in children compared to adults, whereas PDEs showed the opposite age difference. Higher γαATP and lower Pi were found in children compared to adults. The age group differences were particularly salient in the association cortices and anterior white matter. Among children, age correlated negatively with PMEs and positively with PDEs in association cortices. Compared to children, adults had lower intracellular pH. The results suggest reduction in membrane synthesis and increase in membrane degradation in adolescents and to a greater degree in adults compared to younger children. Concomitant reduction in γαATP and increase in Pi are consistent with reduced energy consumption in adolescents and further drop in middle-aged and older adults, although it is impossible to distinguish declines in energy supply from reduced demand due to shrinking neuropil, without longitudinal studies.

Transarterial Embolization Using an Inorganic Phosphate Binder Modulates Immunity and Angiogenesis-related Factors in a Rat Model of Liver Cancer

PurposeTo determine how low inorganic phosphate stress (LIPS) induced by sevelamer transartieral embolization (S-TAE) affects immune regulation and angiogenesis in hepatocellular carcinoma (HCC). Material and MethodsTranscatheter arterial embolization (TAE) using conventional lipiodol plus Poly (vinyl alcohol) (PVA) microsphere and S-TAE were conducted on a McA-RH7777 orthotopic liver tumor model in rats, followed by the assessment of alterations in immunity- and angiogenesis-related factors. The cells were cultured under hypoxic conditions and stimulated with LIPS to analyze the modulation of programmed cell death 1 ligand 1 (PD-L1), vascular endothelial growth factor (VEGFα), and transforming growth factor-β1 (TGF-β1) expression through Western blotting, qRT‒PCR, and immunofluorescence assays. Cell migratory capacity and angiogenesis were also evaluated. ResultsTAE increased the expression of neoplastic PD-L1 and VEGFα, and S-TAE, which depletes intratumoral Pi, downregulated the expression of PD-L1, VEGFα and TGF-β1, and augmented the infiltration of CD8+ T-cells, thereby inhibited angiogenesis and activated anticancer immunity. In vitro, the study demonstrated that LIPS inhibits hypoxia-induced upregulation of PD-L1 expression and the HIF-1α/VEGFα axis. Moreover, LIPS inhibited the tube formation ability of Human Umbilical Vein Endothelial Cells (HUVECs) and the migration ability and epithelial–mesenchymal transition (EMT) process of cancer cells under hypoxic conditions. ConclusionsS-TAE inhibited the expression of PD-L1 and VEGFα, thereby activated anti-tumor immunity and suppressing tumor angiogenesis. All the findings reveal the biology of tumors under low Pi stress and suggest the potential therapeutic value of S-TAE.

Halotolerant phosphate solubilizing bacteria isolated from arid area in Tunisia improve P status and photosynthetic activity of cultivated barley under P shortage

Forty-seven (47) bacterial strains were isolated from soil of Gabes (an arid region in southern Tunisia) and were screened for their ability to produce Indole-3-Acetic Acid (IAA) and to solubilize phosphate (P). The characterization and molecular identification of the most successful P-solubilizing bacteria (PSB) were then carried out. When grown on suitable artificial media, the most salt-tolerant strains also showed the highest P solubilization capacity (up to 126.8 μg ml−1 of released phosphorus after 7 day incubation) and the strongest ability to produce IAA (up to 101.86 μg ml−1 after 3 day incubation). Overall, bacterial isolates displayed a different tolerance to varying pH, temperatures, and salinity. The molecular identification revealed that 11 strains belonged to three genera: Bacillus, Pseudomonas and Mesorhizobium. Inoculation of barley with P-solubilizing bacteria under tricalcium phosphate-induced P shortage significantly improved plant growth (biomass, shoot height, and root length) together with increasing total chlorophyll contents and photosynthetic activity. This was concomitant with (i) higher P uptake and translocation and (ii) increased phosphorus absorption and utilization efficiencies (PAE and PUE), which is indicative of a better plant P nutrition under P scarcity. Taken together, we provide strong arguments showing that bacteria native to extreme environments display PSB potential making them promising candidates to mitigate low Pi availability for crop plants.

Pilot Study for Deciphering Post-Translational Modifications and Proteoforms of Tau Protein by Capillary Electrophoresis-Mass Spectrometry.

Abnormal accumulation of tau protein in the brain is one pathological hallmark of Alzheimer's disease (AD). Many tau protein post-translational modifications (PTMs) are associated with the development of AD, such as phosphorylation, acetylation, and methylation. Therefore, a complete picture of the PTM landscape of tau is critical for understanding the molecular mechanisms of AD progression. Here, we offered a pilot study of combining two complementary analytical techniques, capillary zone electrophoresis (CZE)-tandem mass spectrometry (MS/MS) and reversed-phase liquid chromatography (RPLC)-MS/MS, for bottom-up proteomics of recombinant human tau-0N3R. We identified 50 phosphorylation sites of tau-0N3R in total, which is about 25% higher than that from RPLC-MS/MS alone. CZE-MS/MS provided more PTM sites (i.e., phosphorylation) and modified peptides of tau-0N3R than RPLC-MS/MS, and its predicted electrophoretic mobility helped improve the confidence of the identified modified peptides. We developed a highly efficient capillary isoelectric focusing (cIEF)-MS technique to offer a bird's-eye view of tau-0N3R proteoforms, with 11 putative tau-0N3R proteoforms carrying up to nine phosphorylation sites and lower pI values from more phosphorylated proteoforms detected. Interestingly, under native-like cIEF-MS conditions, we observed three putative tau-0N3R dimers carrying phosphate groups. The findings demonstrate that CE-MS is a valuable analytical technique for the characterization of tau PTMs, proteoforms, and even oligomerization.

A lipid synthase maintains metabolic flux for jasmonate synthesis to regulate root growth and phosphate homeostasis.

Plants require phosphate (Pi) for proper growth and development but often face scarcity of this vital nutrient in the soil. Pi-starvation triggers membrane lipid remodeling to utilize the membrane phospholipid-bound Pi in plants. In this process, phospholipids are replaced by non-Pi-containing galactolipids (MGDG, DGDG) and sulfolipids. The galactolipids ratio (MGDG:DGDG) is suggested to influence jasmonic acid (JA) biosynthesis. However, how the MGDG:DGDG ratio, JA levels, and root growth are coordinated under Pi deficiency in rice (Oryza sativa) remains unknown. Here, we characterized DGDG synthase 1 (OsDGD1) for its role in regulating root development by maintaining metabolic flux for JA biosynthesis. We showed that OsDGD1 is responsive under low Pi and is under the direct control of Phosphate Starvation Response 2 (OsPHR2), the master regulator of low Pi adaptations. Further, OsDGD1 knockout (KO) lines showed marked phenotypic differences compared to the wild type (WT), including a significant reduction in root length and biomass, leading to reduced Pi uptake. Further, lipidome analyses revealed reduced DGDG levels in the KO line, leading to reduced membrane remodeling, thus affecting P utilization efficiency. We also observed an increase in the MGDG: DGDG ratio in KO lines, which enhanced the endogenous JA levels and signaling. This imbalance of JA in KO plants led to changes in auxin levels, causing drastic root growth inhibition. These findings indicate the critical role of OsDGD1 in maintaining optimum levels of JA during Pi deficiency for conducive root growth. Besides acting as signaling molecules and structural components, our study widens the role of lipids as metabolic flux controllers for phytohormone biosynthesis.

A comprehensive view on the fisetin impact on colorectal cancer in animal models: Focusing on cellular and molecular mechanisms.

Flavonoids, including fisetin, have been linked to a reduced risk of colorectal cancer (CRC) and have potential therapeutic applications for the condition. Fisetin, a natural flavonoid found in various fruits and vegetables, has shown promise in managing CRC due to its diverse biological activities. It has been found to influence key cell signaling pathways related to inflammation, angiogenesis, apoptosis, and transcription factors. The results of this study demonstrate that fisetin induces colon cancer cell apoptosis through multiple mechanisms. It impacts the p53 pathway, leading to increased levels of p53 and decreased levels of murine double minute 2, contributing to apoptosis induction. Fisetin also triggers the release of important components in the apoptotic process, such as second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI and cytochrome c. Furthermore, fisetin inhibits the cyclooxygenase-2 and wingless-related integration site (Wnt)/epidermal growth factor receptor/nuclear factor kappa B signaling pathways, reducing Wnt target gene expression and hindering colony formation. It achieves this by regulating the activities of cyclin-dependent kinase 2 and cyclin-dependent kinase 4, reducing retinoblastoma protein phosphorylation, decreasing cyclin E levels, and increasing p21 levels, ultimately influencing E2 promoter binding factor 1 and cell division cycle 2 (CDC2) protein levels. Additionally, fisetin exhibits various effects on CRC cells, including inhibiting the phosphorylation of Y-box binding protein 1 and ribosomal S6 kinase, promoting the phosphorylation of extracellular signal-regulated kinase 1/2, and disrupting the repair process of DNA double-strand breaks. Moreover, fisetin serves as an adjunct therapy for the prevention and treatment of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PIK3CA)-mutant CRC, resulting in a reduction in phosphatidylinositol-3 kinase (PI3K) expression, Ak strain transforming phosphorylation, mTOR activity, and downstream target proteins in CRC cells with a PIK3CA mutation. These findings highlight the multifaceted potential of fisetin in managing CRC and position it as a promising candidate for future therapy development.

Variation in foliar inorganic phosphorus concentrations in perennial ryegrass (Lolium perenne L.)

ABSTRACT Breeding ryegrass for reduced inorganic phosphorus (Pi) concentrations in leaf vacuoles could lower pasture P fertiliser requirements with economic and environmental benefits. We investigated foliar Pi% accumulation characteristics of a range of ryegrass cultivars and ecotypes in glasshouse experiments, and ryegrass cultivars from two field trials. Pi in ryegrass was also compared with Pi in cocksfoot, tall fescue, prairie grass and Phalaris in a glasshouse experiment. Pi expressed as a percentage of leaf total phosphorus was higher (average 82.5%) in the older ryegrass cultivars – Ruanui, and Nui and the New Zealand hill country ecotypes (85%) than in more recently bred cultivars like Aberdart and One50 (74.7%). In the other grass species, foliar Pi% was lowest in prairie grass, intermediate in tall fescue with the highest values in cocksfoot, Phalaris and ryegrass. The results suggest that including a lower Pi concentration in future ryegrass breeding programmes might improve ryegrass P use efficiency without compromising growth rates.

An intracellular phosphorus-starvation signal activates the PhoB/PhoR two-component system in Salmonella enterica.

Bacteria acquire P primarily as inorganic orthophosphate (Pi, PO43-). Once internalized, Pi is rapidly assimilated into biomass during the synthesis of ATP. Because Pi is essential, but excessive ATP is toxic, the acquisition of environmental Pi is tightly regulated. In the bacterium Salmonella enterica (Salmonella), growth in Pi-limiting environments activates the membrane sensor histidine kinase PhoR, leading to the phosphorylation of its cognate transcriptional regulator PhoB and subsequent transcription of genes involved in adaptations to low Pi. Pi limitation promotes PhoR kinase activity by altering the conformation of a membrane signaling complex comprised of PhoR, the multicomponent Pi transporter system PstSACB and the regulatory protein PhoU. However, the identity of the Pi-starvation signal and how it controls PhoR activity remain unknown. Here, we identify conditions where the PhoB and PhoR signal transduction proteins can be maintained in an inactive state when Salmonella is grown in media lacking Pi. Our results demonstrate that PhoB/PhoR is activated by an intracellular P-insufficiency signal.IMPORTANCEIn enteric bacteria, the transcriptional response to phosphorus (P) starvation is controlled by a specialized signal transduction system comprised of a membrane-bound, multicomponent signal sensor, and a cytoplasmic transcriptional factor. Whereas this system has been primarily studied in the context of phosphate (Pi) starvation, it is currently unknown how this stress initiates signal transduction. In the current study, we establish that this signaling system is regulated by a cytoplasmic signal arising from insufficient P. We demonstrate that rather than responding to extracellular conditions, cells couple the activation of their P starvation response to the availability of cytoplasmic P. This regulatory logic may enable cells to prevent toxicity resulting from excessive Pi acquisition and hinder the onset of a P starvation response when their metabolic demands are being met through the consumption of P sources other than Pi.

Prospective multicenter study to describe the prevalence, outcomes, and management of phosphate disorders in intensive care patients: Study protocol for part B of the international GUTPHOS study

BackgroundAberrations in blood phosphate (Pi) levels, whether presenting as hypo- or hyperphosphatemia, appear to be associated with clinical complications and adverse outcomes in patients admitted to an intensive care unit (ICU). However, the prevalence of Pi disorders and the association with subsequent factors and organ failures leading to death in ICU patients are poorly described. Despite endeavors to understand the etiology and treatment of low Pi levels from systematic reviews and meta-analyses, the literature lacks comprehensive guidance for managing hypophosphatemia. Hyperphosphatemia, on the other hand, appears to be associated with higher mortality among critically ill patients, yet its prevalence among ICU patients, particularly following phosphate repletion, remains unknown. The present study aims to investigate the prevalence of Pi abnormalities upon ICU admission and their incidence during the first week of ICU stay, the factors associated with Pi alterations, and the effect of phosphate repletion on the normalization of Pi levels, and its associations with clinical outcomes. MethodsThis multicentre, prospective, non-interventional cohort study will include at least 1000 consecutive adult ICU patients (≥18 years) as part B of the GUTPHOS study. Sites are eligible if an anticipated minimal inclusion of 50 eligible patients during eight weeks from January 2024 until June 2024 and daily phosphate measurements during the first seven days of ICU stay are expected. All consecutive adult patients admitted to a participating ICU during the recruitment period, lasting up to eight weeks, or up to 120 patients if enrollment reaches that limit earlier, will be included. Study parameters include study site characteristics, patient demographics, daily assessment of Pi levels, Pi-related treatment, feeding details, renal replacement therapy details, the incidence of refeeding-associated hypophosphatemia and administered medication (during the first seven calendar days of ICU stay). There will be a follow-up period of a maximum of 90 days to document 28- and 90-day all-cause mortality as the primary outcome. Multiple logistic regression will be used to assess independent associations with mortality in addition to Receiver Operating Characteristics curves to identify cut-off Pi values associated with mortality and overcorrection. Linear mixed models will be conducted to assess Pi treatment effects. Subgroup analyses will be performed based on Pi abnormalities observed during ICU admission, categorized as normo-, hypo-, hyper-, or mixed, along with its severity (mild, moderate, or severe). DiscussionThe GUTPHOS study will be the first multicentre, prospective observational cohort study to investigate the prevalence, management practices, and consequent outcomes associated with Pi abnormalities during the first week of ICU admission. Its results may bridge the current evidence gap in repletion protocols while establishing the groundwork for a subsequent randomized controlled trial. Clinical trial registryNCT05909722.

Mining key genes associated with phosphorus deficiency through genome-wide identification and characterization of cucumber SPX family genes

BackgroundProteins harboring the SPX domain are crucial for the regulation of phosphate (Pi) homeostasis in plants. This study aimed to identify and analyze the entire SPX gene family within the cucumber genome.ResultsThe cucumber genome encompassed 16 SPX domain-containing genes, which were distributed across six chromosomes and categorized into four distinct subfamilies: SPX, SPX-MFS, SPX-EXS and SPX-RING, based on their structure characteristics. Additionally, gene duplications and synteny analysis were conducted for CsSPXs, revealing that their promoter regions were enriched with a variety of hormone-responsive, biotic/abiotic stress and typical P1BS-related elements. Tissue expression profiling of CsSPX genes revealed that certain members were specifically expressed in particular organs, suggesting essential roles in cucumber growth and development. Under low Pi stress, CsSPX1 and CsSPX2 exhibited a particularly strong response to Pi starvation. It was observed that the cucumber cultivar Xintaimici displayed greater tolerance to low Pi compared to black-spined cucumber under low Pi stress conditions. Protein interaction networks for the 16 CsSPX proteins were predicted, and yeast two-hybrid assay revealed that CsPHR1 interacted with CsSPX2, CsSPX3, CsSPX4 and CsSPX5, implying their involvement in the Pi signaling pathway in conjunction with CsPHR1.ConclusionThis research lays the foundation for further exploration of the function of the CsSPX genes in response to low Pi stress and for elucidating the underlying mechanism.

Establishing nomograms for predicting disease-free survival and overall survival in patients with breast cancer

Background Prognostic factors-based nomograms have been utilised to detect the likelihood of the specific cancer events. We have focused on the roles of aldehyde dehydrogenase 1 (ALDH1) and p-AKT in predicting the prognosis of BC patients. This study was designed to establish nomograms based on the integration of aldehyde dehydrogenase 1 (ALDH1) and p-AKT in predicting the disease-free survival (DFS) and overall survival (OS) of breast cancer (BC) patients. Methods Demographic and clinical data were obtained from BC patients admitted to our hospital between September 2015 and August 2016. Univariate and multivariate Cox regression analyses were utilised to analyse the risk factors of recurrence and mortality. The nomograms for predicting the DFS and OS were established using the screened risk factors. Stratified analysis was performed with the cut-off value of exp (pi) of 4.0-fold in DFS and OS, respectively. Results Multivariate Cox regression analysis indicated that ALDH, p-AKT and pathological stage III were independent risk factors for the recurrence among BC patients. ALDH1, p-AKT, pathological stage III and ER-/PR-/HER2- were independent risk factors for the mortality among BC patients. The established nomograms based on these factors were effective for predicting the DFS and OS with good agreement to the calibration curve and acceptable area under the receiver operating characteristic (ROC) curve. Finally, stratified analyses showed patients with a low pi showed significant decrease in the DFS and OS compared with those of high risk. Conclusion We established nomograms for predicting the DFS and OS of BC patients based on ALDH1, p-AKT and pathological stages. The ER-/PR-/HER2- may be utilised to predict the OS rather than DFS in the BC patients.

Mechanisms of vacuolar phosphate efflux supporting soybean root hair growth in response to phosphate deficiency.

Phosphorus is an essential macronutrient for plant growth and development. In response to phosphate (Pi) deficiency, plants rapidly produce a substitutive amount of root hairs; however, the mechanisms underlying Pi supply for root hair growth remain unclear. Here, we observed that soybean (Glycine max) plants maintain a consistent level of Pi within root hairs even under external Pi deficiency. We therefore investigated the role of vacuole-stored Pi, a major Pi reservoir in plant cells, in supporting root hair growth under Pi-deficient conditions. Our findings indicated that two vacuolar Pi efflux (VPE) transporters, GmVPE1 and GmVPE2, remobilize vacuolar stored Pi to sustain cytosolic Pi content in root hair cells. Genetic analysis showed that double mutants of GmVPE1 and GmVPE2 exhibited reduced root hair growth under low Pi conditions. Moreover, GmVPE1 and GmVPE2 were highly expressed in root hairs, with their expression levels significantly upregulated by low Pi treatment. Further analysis revealed that GmRSL2 (ROOT HAIR DEFECTIVE 6-like 2), a transcription factor involved in root hair morphogenesis, directly binds to the promoter regions of GmVPE1 and GmVPE2, and promotes their expressions under low Pi conditions. Additionally, mutants lacking both GmRSL2 and its homolog GmRSL3 exhibited impaired root hair growth under low Pi stress, which was rescued by overexpressing either GmVPE1 or GmVPE2. Taken together, our study has identified a module comprising vacuolar Pi exporters and transcription factors responsible for remobilizing vacuolar Pi to support root hair growth in response to Pi deficiency in soybean.

A pilot study for deciphering post-translational modifications and proteoforms of tau protein by capillary electrophoresis-mass spectrometry.

Abnormal accumulation of tau proteins is one pathological hallmark of Alzheimer□s disease (AD). Many tau protein post-translational modifications (PTMs) are associated with the development of AD, such as phosphorylation, acetylation, and methylation. Therefore, a complete picture of PTM landscape of tau is critical for understanding the molecular mechanisms of AD progression. Here, we offered a pilot study of combining two complementary analytical techniques, capillary zone electrophoresis (CZE)-tandem mass spectrometry (MS/MS) and reversed-phase liquid chromatography (RPLC)-MS/MS, for bottom-up proteomics of recombinant human tau-0N3R. We identified 53 phosphorylation sites of tau-0N3R in total, which is about 30% higher than that from RPLC-MS/MS alone. CZE-MS/MS provided more PTM sites (i.e., phosphorylation) and modified peptides of tau-0N3R than RPLC-MS/MS, and its predicted electrophoretic mobility helped improve the confidence of the identified modified peptides. We developed a highly efficient capillary isoelectric focusing (cIEF)-MS technique to offer a bird's-eye view of tau-0N3R proteoforms, with 11 putative tau-0N3R proteoforms carrying up to nine phosphorylation sites and lower pI values from more phosphorylated proteoforms detected. Interestingly, under a native-like cIEF-MS condition, we observed three putative tau-0N3R dimers carrying phosphate groups. The findings demonstrate that CE-MS is a valuable analytical technique for the characterization of tau PTMs, proteoforms, and even oligomerization.