Pi Treatment Research Articles

Different mechanisms drive the performance of native and invasive woody species in response to leaf phosphorus supply during periods of drought stress and recovery

The effects of drought stress and leaf phosphorus (Pi) supply on photosynthetic metabolism in woody tropical species are not known, and given the recent global environmental change models that forecast lower precipitation rates and periods of prolonged drought in tropical areas, this type of study is increasingly important. The effects of controlled drought stress and Pi supply on potted young plants of two woody species, Anadenanthera colubrina (native) and Prosopis juliflora (invasive), were determined by analyzing leaf photosynthetic metabolism, biochemical properties and water potential. In the maximum stress, both species showed higher leaf water potential (Ψl) in the treatment drought +Pi when compared with the respective control −Pi. The native species showed higher gas exchange under drought +Pi than under drought –Pi conditions, while the invasive species showed the same values between drought +Pi and −Pi. Drought affected the photochemical part of photosynthetic machinery more in the invasive species than in the native species. The invasive species showed higher leaf amino acid content and a lower leaf total protein content in both Pi treatments with drought. The two species showed different responses to the leaf Pi supply under water stress for several variables measured. In addition, the strong resilience of leaf gas exchange in the invasive species compared to the native species during the recovery period may be the result of higher efficiency of Pi use. The implications of this behavior for the success of this invasive species in semiarid environments are discussed.

Gender differences in HIV infection: Is there a problem? Analysis from the SCOLTA cohorts

ObjectivesEvaluate gender differences with regard to baseline characteristics and outcome of therapy in cohorts of the SCOLTA (surveillance cohort long-term toxicity of antiretrovirals) project. MethodsThe SCOLTA project is an active pharmacovigilance system for new antiretroviral drugs. Since 2002, patients were enrolled in nine cohorts (lopinavir, tenofovir, atazanavir, fosamprenavir, enfuvirtide, tipranavir, darunavir, raltegravir and maraviroc). ResultsTwo thousand one hundred and fifty-four patients were included in 5 PI cohorts; 607 (28.2%) were female. Women were younger and less frequently HCV-coinfected than men. At study entry, they were less frequently in CDC stage C, but CD4+ cells/mm3 and detectable HIV-RNA were not different by gender. Women had triglycerides alterations less frequently than men, but showed a higher proportion of low HDL-cholesterol. Women were protected from incident grade 2-4 triglycerides increase (odds ratio=0.39, 95% confidence interval 0.18–0.88; P=0.02). Mean CD4+ cell count increased in both men and women; despite a non-significantly lower initial CD4+ level, women had a better immunological recovery. Women discontinued PI treatment for adverse events and their own will more frequently. ConclusionsIn these cohorts, gender distribution mirrored the Italian HIV population. Women were younger than men when they started their first ARV therapy and when they entered our cohorts. On the same treatment, they had a better immune response, though no significant difference emerged on virologic control and treatment durability. As compared to men, women appeared at lower risk of hypertriglyceridaemia. They stopped PI-based treatment of their own will more frequently than men, suggesting the need for a focused effort on adherence.

Comparable Long-Term Efficacy of Lopinavir/Ritonavir and Similar Drug-Resistance Profiles in Different HIV-1 Subtypes

BackgroundAnalysis of potentially different impact of Lopinavir/Ritonavir (LPV/r) on non-B subtypes is confounded by dissimilarities in the conditions existing in different countries. We retrospectively compared its impact on populations infected with subtypes B and C in Israel, where patients infected with different subtypes receive the same treatment.MethodsClinical and demographic data were reported by physicians. Resistance was tested after treatment failure. Statistical analyses were conducted using SPSS.Results607 LPV/r treated patients (365 male) were included. 139 had HIV subtype B, 391 C, and 77 other subtypes. At study end 429 (71%) were receiving LPV/r. No significant differences in PI treatment history and in median viral-load (VL) at treatment initiation and termination existed between subtypes. MSM discontinued LPV/r more often than others even when the virologic outcome was good (p = 0.001). VL was below detection level in 81% of patients for whom LPV/r was first PI and in 67% when it was second (P = 0.001). Median VL decrease from baseline was 1.9±0.1 logs and was not significantly associated with subtype. Median CD4 increase was: 162 and 92cells/µl, respectively, for patients receiving LPV/r as first and second PI (P = 0.001), and 175 and 98, respectively, for subtypes B and C (P<0.001). Only 52 (22%) of 237 patients genotyped while under LPV/r were fully resistant to the drug; 12(5%) were partially resistant. In48%, population sequencing did not reveal resistance to any drug notwithstanding the virologic failure. No difference was found in the rates of resistance development between B and C (p = 0.16).ConclusionsTreatment with LPV/r appeared efficient and tolerable in both subtypes, B and C, but CD4 recovery was significantly better in virologically suppressed subtype-B patients. In both subtypes, LPV/r was more beneficial when given as first PI. Mostly, reasons other than resistance development caused discontinuation of treatment.

Pi treatment for the constituent rectangles of the superscribed square in the study of exact area of the inscribed circle and its value of Pi (SV University Method

Pi treatment for the constituent rectangles of the superscribed square in the study of exact area of the inscribed circle and its value of Pi (SV University Method

The influence of phosphorus availability and Laccaria bicolor symbiosis on phosphate acquisition, antioxidant enzyme activity, and rhizospheric carbon flux in Populus tremuloides

Many forest tree species are dependent on their symbiotic interaction with ectomycorrhizal (ECM) fungi for phosphorus (P) uptake from forest soils where P availability is often limited. The ECM fungal association benefits the host plant under P limitation through enhanced soil exploration and increased P acquisition by mycorrhizas. To study the P starvation response (PSR) and its modification by ECM fungi in Populus tremuloides, a comparison was made between nonmycorrhizal (NM) and mycorrhizal with Laccaria bicolor (Myc) seedlings grown under different concentrations of phosphate (Pi) in sand culture. Although differences in growth between NM and Myc plants were small, Myc plants were more effective at acquiring P from low Pi treatments, with significantly lower k m values for root and leaf P accumulation. Pi limitation significantly increased the activity of catalase, ascorbate peroxidase, and guaiacol-dependent peroxidase in leaves and roots to greater extents in NM than Myc P. tremuloides. Phosphoenolpyruvate carboxylase activity also increased in NM plants under P limitation, but was unchanged in Myc plants. Formate, citrate, malonate, lactate, malate, and oxalate and total organic carbon exudation by roots was stimulated by P limitation to a greater extent in NM than Myc plants. Colonization by L. bicolor reduced the solution Pi concentration thresholds where PSR physiological changes occurred, indicating that enhanced Pi acquisition by P. tremuloides colonized by L. bicolor altered host P homeostasis and plant stress responses to P limitation. Understanding these plant-symbiont interactions facilitates the selection of more P-efficient forest trees and strategies for tree plantation production on marginal soils.

The effect of different feed on the spawning performance of mud crab Scylla serrata broodstock

&lt;p&gt;Mud crab is one of the 12 aquaculture commodities of Ministry of Maritime Affairs and Fisheries. Control of reproduction to increase seed production through feed improvement, is one of the challenges and strategies in the mud crab aquaculture. Due to lack of knowledge about broodstock nutrition lead to producing rate of seeds still relatively low. This study aimed to obtain information on the kind of feed that has specific nutrient and plays a role in increasing the success of spawning and zoea survival. Mud crab of Scylla serrata with initial weight of 500.7±103.4 g, preferably under developed gonads were maintained in a fiber tank measuring length of 2.48 m, width 1.26 m, and a height of 60 cm which is partition sealed into 30×40×60 cm3 to put one crab. Tank was equipped with sand as a substrate as high as 15 cm and seawater system with flow rate of 1 L per six minutes and 25 cm high water. Treatments were consisted of: 1. PI (fresh meat fish of Decapterus sp. with dose of 5%), 2. PSC (fresh meat mixture of Decapterus sp. 1.8%, 3% of squid, and shrimp 1.2%), 3. PB (artificial feed dose of 10%) of BW, each treatment was repeated three times. Parameters measured were the duration of ovarian to mature, egg diameter, hatching rate, fecundity, and zoea production. Data were analyzed using ANOVA. The quality of larval measured by survival and larval fat and protein content. The results showed that crabs treated by PI and PSC showed faster to get mature compared to PB treatment (p&amp;lt;0.05). Hatching rate of larvae in PSC treatment was higher compared to PI and PB treatments (p&amp;lt;0.05). Furthermore, all treatments did not affect egg diameter, fecundity, and the number of zoea (p&amp;gt;0.05). In conclusion, crab which fed fresh meat (PI and PSC) could get mature earlier, and have high percentage of the larval hatching than those of fed by PB. In fact that larvae from broodstock feed of PI has survival as well as protein and fat content were higher than those of fed by PB.&lt;/p&gt;&lt;p&gt;Keywords: spawning perform, broodstock feed, mud crab (Scylla serrata)&lt;/p&gt;

Why Proteasome Inhibitors Cannot ERADicate Multiple Myeloma

Proteasome inhibitors are key parts of our armamentarium against multiple myeloma, but the disease can become resistant through poorly defined mechanisms. In this issue of Cancer Cell, Leung-Hagesteijn and colleagues describe XBP1s(-) subpopulations of tumor cells that are resistant to bortezomib and may account for therapeutic failures in the clinic.

Carbon dioxide diffusion across stomata and mesophyll and photo-biochemical processes as affected by growth CO2 and phosphorus nutrition in cotton

Nutrients such as phosphorus may exert a major control over plant response to rising atmospheric carbon dioxide concentration (CO2), which is projected to double by the end of the 21st century. Elevated CO2 may overcome the diffusional limitations to photosynthesis posed by stomata and mesophyll and alter the photo-biochemical limitations resulting from phosphorus deficiency. To evaluate these ideas, cotton (Gossypium hirsutum) was grown in controlled environment growth chambers with three levels of phosphate (Pi) supply (0.2, 0.05 and 0.01mM) and two levels of CO2 concentration (ambient 400 and elevated 800μmolmol−1) under optimum temperature and irrigation. Phosphate deficiency drastically inhibited photosynthetic characteristics and decreased cotton growth for both CO2 treatments. Under Pi stress, an apparent limitation to the photosynthetic potential was evident by CO2 diffusion through stomata and mesophyll, impairment of photosystem functioning and inhibition of biochemical process including the carboxylation efficiency of ribulose-1,5-bisphosphate carboxylase/oxyganase and the rate of ribulose-1,5-bisphosphate regeneration. The diffusional limitation posed by mesophyll was up to 58% greater than the limitation due to stomatal conductance (gs) under Pi stress. As expected, elevated CO2 reduced these diffusional limitations to photosynthesis across Pi levels; however, it failed to reduce the photo-biochemical limitations to photosynthesis in phosphorus deficient plants. Acclimation/down regulation of photosynthetic capacity was evident under elevated CO2 across Pi treatments. Despite a decrease in phosphorus, nitrogen and chlorophyll concentrations in leaf tissue and reduced stomatal conductance at elevated CO2, the rate of photosynthesis per unit leaf area when measured at the growth CO2 concentration tended to be higher for all except the lowest Pi treatment. Nevertheless, plant biomass increased at elevated CO2 across Pi nutrition with taller plants, increased leaf number and larger leaf area.

Calcium–phosphate treatment of contaminated soil for arsenic immobilization

Abstract The application of As-based herbicides at several industrial sites has resulted in numerous localized areas of As-contaminated soil. In this study, an As-contaminated soil (As = 278 mg/kg) collected from an industrial site located in the southeastern USA was subjected to inorganic phosphate (Pi) treatments. Although Pi treatments have been previously used for flushing As from contaminated soils, in this study, contaminated soil was amended with Pi to study the possible immobilization of As through a co-precipitation mechanism. Specifically, the Pi amendment was aimed at simultaneous flushing of As from the soil with orthophosphoric acid and co-precipitating it as Ca–phosphate–arsenate phases. Bench-scale Pi treatment experiments were performed at different pH conditions, with and without the addition of Ca. Sorption of Pi on BH soil in the presence or absence of additional Ca was determined, along with the associated mobilization of As from the soil. A significant amount of the HNO3-digestible As (up to 55% at pH 4, 10–15% at pH 8, and ∼30% at pH 11) was released from the contaminated soil during the Pi sorption experiments. This increased mobility of As after the addition of Pi resulted from the competitive desorption of As from the soil. Although Pi sorption at high pH (>8) was largely controlled by precipitation, As did not co-precipitate with Pi. Aqueous geochemical modeling indicated that the lack of As co-precipitation during Pi-only treatment primarily resulted from the deficiency of Ca in the system. When additional Ca (16.9 mmol) was supplied along with Pi (3.38 mmol), the mobility of As decreased significantly at circum-neutral to high solution pH. Geochemical modeling suggested that the leachable As in the soil was potentially precipitated as As-bearing Ca–Pi phases. X-ray diffraction analysis of precipitates separated from the treated soil and from the synthetic leachate confirmed that the formation of a poorly crystalline carbonate apatite phase occurred as a consequence of the treatment. The results of this study support the potential application of Ca–Pi treatment for remediation of As-contaminated soil at environmentally relevant pH conditions.

Naturally occurring mutations to HCV protease inhibitors in treatment-naïve patients

BackgroundProtease inhibitors (PIs) to treat hepatitis C (HCV) virus infection have been approved and others are under development.ResultsThe aims of this study were to illustrate natural polymorphisms in the HCV protease and measure the frequency of PI resistance mutations in different HCV genotypes from PI-naïve patients.Direct sequencing of HCV NS3/4A protease was performed in 156 HCV patients naïve to PIs who were infected with genotype 1a (n = 31), 1b (n = 39), 2 (n = 30), 3 (n = 33) and 4 (n = 23).Amino acid (aa) substitutions associated with HCV PI resistance were found in 17/156 (10.8%) sequences. Mutations V36L, T54S, V55A/I, and Q80K/L were observed in 29% of patients with genotype 1a, and V55F, Q80L/N and M175L in 10% of patients with genotype 1b. The mutation V158M was found in 3% of patients with genotype 2, D168Q was present in 100% of patients with genotype 3 and D168E was observed in 13% of patients with genotype 4. In addition, multiple aa polymorphisms not associated with PI resistance were detected in patients with genotypes 1a, 1b and 4.ConclusionsAlthough major PI resistance mutations were not detected, other resistance mutations conferring low level resistance to PIs together with a number of natural polymorphisms were observed in proteases of PI naïve HCV patients. A more extensive analysis is needed to better evaluate the impact of baseline resistance and compensatory mutations in the efficacy of HCV PI treatment.

OsARF16, a transcription factor, is required for auxin and phosphate starvation response in rice (Oryza sativa L.)

Plant responses to auxin and phosphate (Pi) starvation are closely linked. However, the underlying mechanisms connecting auxin to phosphate starvation (-Pi) responses are largely unclear. Here, we show that OsARF16, an auxin response factor, functions in both auxin and -Pi responses in rice (Oryza sativa L.). The knockout of OsARF16 led to primary roots (PR), lateral roots (LR) and root hair losing sensitivity to auxin and -Pi response. OsARF16 expression and OsARF16::GUS staining in PR and LR of rice Nipponbare (NIP) were induced by indole acetic acid and -Pi treatments. In -Pi conditions, the shoot biomass of osarf16 was slightly reduced, and neither root growth nor iron content was induced, indicating that the knockout of OsARF16 led to loss of response to Pi deficiency in rice. Six phosphate starvation-induced genes (PSIs) were less induced by -Pi in osarf16 and these trends were similar to a knockdown mutant of OsPHR2 or AtPHR1, which was a key regulator under -Pi. These data first reveal the biological function of OsARF16, provide novel evidence of a linkage between auxin and -Pi responses and facilitate the development of new strategies for the efficient utilization of Pi in rice.

HIV Gag and PR: partners in resistance to protease and maturation inhibitors

Maturation is an essential step in the HIV-1 life-cycle. It is the transition of immature, non-infectious virus particles to mature and infectious virions triggered by the proteolytic cleavage of the precursor Gag and GagPol polyproteins by the viral enzyme protease. HIV-1 protease recognizes the asymmetric shape of the peptide substrates, rather than a particular amino acid sequence. These peptides have a super-imposable secondary structure, yielding a substrate envelope which fits within the protease substrate-binding region. There are however, a few differences between the substrates in which amino acid side-chains protrude out of the envelope which contribute to the different rates of cleavage. Detailed knowledge of the structure of HIV protease and its substrate has led to the development of specific protease inhibitors (Pls), which have played a major role in antiviral therapy. They bind protease with high affinity but tend to occupy more space than the natural substrates. Resistance to PI is usually a stepwise process in which a substitution in the substrate-binding cleft of the protease is observed first. This results in an overall enlargement of the catalytic site and decreased binding to the inhibitor and, in parallel, to some decrease in binding to the natural substrate and to decreased viral replication. Several studies have identified an association between selection of protease mutations and mutations in the Gag substrate. We have shown that substitutions in the NC/p1 cleavage site alone, without any alterations in the viral protease were selected during in vitro PI exposure. These NC/ p1 changes conferred PI resistance, which could directly be related to increased gag processing. A detailed analysis of clinical isolates of patients on PI therapy also indicated that NC/p1 mutations strongly contribute to PI resistance besides compensating for a loss in viral replication. A novel class of maturation inhibitors target the gag structural proteins instead of the viral protease. Bevirimat (BVM; PA-457, MPC-4326) was the first of these maturation inhibitors to go into clinical trials. The CA/p2 cleavage site has been identified as the bevirimat target region by western-blotting and in vitro resistance selection studies. Clinical studies (phase 2b) showed that baseline polymorphisms slightly downstream of the CA/p2 cleavage site, known as the QVT-motif also confer resistance. We have shown that bevirimat resistance mutations occur more frequently in PI resistant isolates compared to isolates from PI treatment naive individuals and this could mainly be attributed to mutations in the QVT-motif. Furthermore, we have shown that PI resistance mutations alter the bevirimat resistance profiles selected in vitro and impact the level of bevirimat resistance. All these findings signify the strong interaction between the viral protease and its substrate suggesting that PI therapy can have important consequences for future treatment with maturation inhibitors.

Dyslipidaemia in HIV-infected women on antiretroviral therapy. Analysis of 922 patients from the Spanish VACH cohort

BackgroundInformation concerning lipid disturbances in HIV-infected women on antiretroviral therapy (ART) is scarce. The objective of the study is to describe the lipid profile in a large cohort of HIV-infected women on contemporary ART and analyse differences between regimes and patient's characteristics.MethodsObservational, multicentre, cross-sectional study from the Spanish VACH Cohort. 922 women on stable ART without lipid-lowering treatment were included.ResultsMedian age was 42 years, median CD4 lymphocyte count was 544 cells/mm3, and 85.6% presented undetectable HIV-1 viral load. Median total cholesterol (TC) was 189 mg/dL (interquartile range, IQR, 165-221), HDL cholesterol 53 mg/dL (IQR, 44-64), LDL cholesterol 108 mg/dL (IQR, 86-134), and triglycerides 116 mg/dL (IQR, 85-163). Mean accumulated time on ART was 116 months; 47.4% were on NNRTI-based regimes, 44.7% on PI, and 6.7% on only-NRTI therapy. 43.8% were also hepatitis C (HCV) coinfected. Patients on PI treatment presented higher TC/HDL ratio than those on NNRTI (p < 0.001). Significantly higher HDL values were observed in NNRTI-treated patients. HCV-coinfected patients presented lower TC/HDL ratio than the non HCV-coinfected. In multivariate analysis, factors independently associated with TC/HDL ratio were age, triglyceride levels and HCV co-infection. PI treatment presented a non-significant association with higher TC/HDL ratio.ConclusionsIn HIV-infected women, the NNRTI-based ART is associated with a better lipid profile than the PI-based. Factors unrelated to ART selection may also exert an independent, significant influence on lipids; in particular, age, and triglyceride levels are associated with an increased TC/HDL ratio while HCV co-infection is associated with a reduced TC/HDL ratio.

Application of inorganic carrier-based formulations of fluorescent pseudomonads and Piriformospora indica on tomato plants and evaluation of their efficacy

Fluorescent pseudomonads are widely used as bioinoculants for improving plant growth and controlling phytopathogenic fungi. Piriformospora indica (Pi), a symbiotic root endophyte, also has beneficial effects on a number of plants. The present study focuses on the improvement of growth yields of tomato plants and control of Fusarium wilt using inorganic carrier-based formulations of two fluorescent pseudomonad strains (R62 and R81) and Pi. The inorganic carrier-based formulations of pseudomonad strains and Pi were tested for plant growth promotion of tomato plants under glass house and field conditions. In controlled glass house experiments, 8·8-fold increase in dry root weight and 8·6-fold increase in dry shoot weight were observed with talcum powder-based consortium formulation of R81 and Pi. Field trial experiments ascertained the glfass house results with a considerable amount of increase in plant growth responses, and amongst all the treatments, R81 + Pi treatment performed consistently well in field conditions with an increase of 2·6-, 3·1- and 3·9-fold increase in dry root weight, shoot weight and fruit yield, respectively. The fluorescent pseudomonad R81 and Pi also acted as biocontrol agents, as their treatments could control the incidence of wilt disease caused by Fusarium oxysporum f.sp. lycopersici in tomato plants under glass house conditions. The culture broths of pseudomonads R62, R81 and Pi were successfully used for development of talcum- and vermiculite-based bioinoculant formulations. In controlled glasshouse experiments, the talcum-based bioinoculant formulations performed significantly better over vermiculite-based formulations. In field experiments the talcum-based consortium formulation of pseudomonad R81 and Pi was most effective. This study suggests that the formulations of pseudomonad strains (R62 and R81) and Pi can be used as bioinoculants for improving the productivity of tomato plants. The application of such formulations is a step forward towards sustainable agriculture.

Plant growth, leaf photosynthesis, and nutrient‐use efficiency of citrus rootstocks decrease with phosphite supply

AbstractSome formulations of phosphite (Phi) have been recommended as a source of P nutrition for several crops including citrus even though there are known negative effects of Phi on plant growth. Changes in plant growth and metabolism after Phi application should be reflected in altered nutrient‐use efficiency and leaf photosynthesis. We carried out a greenhouse study using seedlings of two contrasting citrus (Citrus spp.) rootstocks, Carrizo citrange (CC) and Smooth Flat Seville (SFS), growing in either aerated hydroponic culture or sterilized native sandy soil. Plants were subjected to four P treatments: No P (control, P0); 0.5 mM Pi (PO4‐P); 0.25 mM Pi + 0.25 mM Phi (Pi + Phi), or 0.5 mM Phi (Phi). Photosynthetic characteristics, concentrations of total P (Pt) and soluble PO4‐P or PO3‐P in leaves and roots, and plant growth were evaluated after 80–83 d P treatments. Overall, the Pi plants had the highest Pt (total P) and total plant dry weight while the P0 plants had the lowest Pt but highest total root length and root‐to‐shoot ratio. Leaf chlorophyll (SPAD readings) and net assimilation of CO2 (ACO2) of the P0 and Phi plants were similarly lower than those of Pi and Pi + Phi plants. Growth responses of the Pi + Phi treatment were intermediate between the Pi and Phi treatments. Although Phi increased Pt and soluble‐PO4‐P concentration in leaves and roots above the P0 treatment, this did not translate into increased plant growth. In fact, the Phi treatment had some phytotoxic symptoms, impaired P‐ and N‐utilization efficiency for biomass production as well as lower nutrient‐use efficiency in the photosynthetic process. Thus, these two rootstocks could not use Phi as a nutritional source of P.

The fate of Npt2a: the role of the actin cytoskeleton and SNARE proteins

Npt2a is responsible for 70% of phosphate (Pi) reabsorption by kidney proximal tubules. The intracellular events leading to apical membrane (AM) trafficking of Npt2a remain unknown. We hypothesized that regulation of apical membrane trafficking of Npt2a is dependent on actin cytoskeleton (AC) and SNARE protein interactions. To study AM trafficking, we first treated opossum kidney (OK) cells with parathyroid hormone to deplete Npt2a followed by treatment with low Pi medium (24 h) to stimulate AM trafficking +/− pharmacologic agents that disrupt AC. Disruption of AC by colchicine (1μM, 83.6%) and cytochalasin D (30 μM, 72.5%) significantly impaired AM trafficking of Npt2a. Surprisingly, Pi transport was not significantly impaired. To determine SNARE dependence of AM trafficking of Npt2a, we transduced SNAP23 and syntaxin, peptide inhibitors of SNARE protein interactions, prior to low Pi treatment. Npt2a AM trafficking was inhibited both by SNAP23 (51.7%) and syntaxin (25.8%). SNAP23 decreased AM trafficking of PiT2 (26.2%) but not syntaxin peptide. Our data support our hypothesis and suggest that AM trafficking of Na-Pi cotransporters is differentially regulated. Funds: VAMC and AHA.

High pressure-assisted encapsulation of vitamin D2 in reassembled casein micelles

For the encapsulation of vitamin D2, native casein micelles and vitamin D2 with or without additional Ca2+–Pi were treated at 600 MPa and 37 °C for 60 min. The pressure release rate was set at 20 or 600 MPa/min. Vitamin D2 was quantified by reversed-phase high-performance liquid chromatography, and physical properties of the micelles were analysed by photon correlation spectroscopy. The results demonstrate that simultaneous application of Ca2+–Pi and high pressure treatment with a fast release rate significantly increased loading of vitamin D2 per casein by 6.9-fold. The addition of Ca2+–Pi enhanced micelle aggregation and the vitamin was entrapped within the formed aggregates. However, high pressure treatment without Ca2+–Pi with a slow pressure release rate revealed similar results, increasing vitamin D2 per casein by 6.7-fold. The vitamin D2 loading in reassembled casein micelles is supposed to be due to hydrophobic interactions between the hydrophobic domains of the micelles.

Novel molecular mechanisms by inorganic phosphate in osteosarcoma U2OS cells

Osteosarcoma is the most common malignant primary bone tumor in children and adolescents and is characterized by a high metastatic potential. Its clinical outcome remains discouraging despite aggressive treatments. Thus, novel therapeutic approaches are needed. Recent results indicate that inorganic phosphate (Pi) is capable of affecting specific signal transduction pathways and of acting as an active regulator of cell behaviour. Previously, we found that Pi inhibits proliferation of human osteosarcoma U2OS cells via an adenylate cyclase/cAMP mediated mechanism. Here, we report that upon Pi treatment, U2OS cells become extremely hard to dislodge with trypsin. The lack of sensitivity to the trypsin action was paralleled by relevant changes in integrin subunits expression and accompanied by an increase of cell adhesion in cell-matrix adhesion assays. Interestingly, exposure of U2OS cells to Pi results also in a strong activation and protein level up-regulation of Rap1 small GTPase and in an early increase followed by a sustained inhibition of Erk1/2 phosphorylation. Importantly, the Pi-induced increase of cell adhesion was enforced by a cAMP analogue which specifically activated Epac/Rap1 and insensitive to PKA and MEK1/2 inhibitors. Our results enforce the evidences of inorganic phosphate as a signalling molecule, identify beta3 integrin, Rap1, ERK1/2 as proteins whose expression and function are relevantly affected by Pi in osteosarcoma U2OS cells The clinical significance and potential therapeutic applications by our data will be discussed.

Povidone–iodine application induces corneal cell death through fixation

Background/aimsPovidone–iodine (PI) is commonly used as a preoperative disinfectant; however, it has been shown to be cytotoxic. The present study was performed to investigate the mechanism by which PI causes...

Expression analysis suggests potential roles of microRNAs for phosphate and arbuscular mycorrhizal signaling in Solanum lycopersicum

MicroRNAs (miRNAs) have emerged as a class of gene expression regulators that play crucial roles in many biological processes. Recently, several reports have revealed that micoRNAs participate in regulation of symbiotic interaction between plants and nitrogen-fixing rhizobia bacteria. However, the role of miRNAs in another type of plant-microbe interaction, arbuscular mycorrhizal (AM) symbiosis, has not been documented. We carried out a microarray screen and poly(A)-tailed reverse transcriptase-polymerase chain reaction (RT-PCR) validation for miRNA expression in tomato (Solanum lycopersicum) under varying phosphate (Pi) availability and AM symbiosis conditions. In roots, miRNA158, miRNA862-3p, miRNA319, miRNA394 and miR399 were differentially regulated under three different treatments, Pi sufficient (+P ), Pi deficient (-P) and AM symbiosis (+M ). In leaves, up to 14 miRNAs were up- or down-regulated under either or both of the Pi treatments and AM symbiosis, of which miR158, miR319 and miR399 were responsive to the treatments in both roots and leaves. We detected that miR395, miR779.1, miR840 and miR867 in leaves were specifically responsive to AM symbiosis, which is independent of Pi availability, whereas miR398 in leaves and miR399 in both roots and leaves were Pi starvation induced. Furthermore, miR158 in roots as well as miR837-3p in leaves were responsive to both Pi deprivation and AM colonization. In contrast, miR862-3p in roots was responsive to Pi nutrition, but not to AM symbiosis. Moreover, the group of miRNA consisting miR319 and miR394 in roots and miR158, miR169g*, miR172, miR172b*, miR319, miR771 and miR775 in leaves were up- and down-regulated by Pi starvation, respectively. The data suggest that altered expression of distinct groups of miRNA is an essential component of Pi starvation-induced responses and AM symbiosis.