A Spectrofluorophotometrical Method Based on Fura-2-AM Probe to Determine Cytosolic Ca2+ Level in Pseudomonas syringae Complex Bacterial Cells.

Calcium signaling is an emerging mechanism by which bacteria respond to environmental cues. To measure the intracellular free-calcium concentration in bacterial cells, [Ca2+]i, a simple spectrofluorometric method based on the chemical probe Fura 2-acetoxy methyl ester (Fura 2-AM) is here presented using Pseudomonad bacterial cells. This is an alternative and quantitative method that can be completed in a short period of time with low costs, and it does not require the induction of heterologously expressed protein-based probes like Aequorin. Furthermore, it is possible to verify the properties of membrane channels involved in Ca2+ entry from the extracellular matrix. This method is in particular valuable for measuring [Ca2+]i in the range of 0.1-39.8 µM in small cells like those of prokaryotes.

Synthesis and characterization of carnitine nitro-derivatives.

Nitric oxide (NO) acts as an autacoid molecule that diffuses from its endothelial production site to the neighboring muscular cells. NO-donors are often used to mimic the physiological effects of NO in biological systems. Organic nitrates are commonly used as NO-donors; the most popular, glycerol trinitrate (GTN), has been used in therapy for more than a century. Carnitine nitrates have been synthesized using an endogenous non-toxic molecule: (L)-carnitine. The biotransformation of carnitine nitro-derivatives in biological fluids (saliva and blood plasma) and in red blood cells (RBC) has been monitored by an electrochemical assay and the interaction of carnitine nitrates with the plasma membrane carnitine transporter has been investigated. Differences in the way carnitine nitro-derivatives are metabolized in biological fluids and cells and transported by OCTN2 transporter are modulated by the chemical structures and by the length of the acyl template which carries the nitro-group.

The cytosolic calcium concentration is affected by S-nitrosocysteine in human lymphomonocytes.

The homeostasis of cytosolic calcium [Ca2+](c) in mammalian cells is a complex phenomenon, requiring the contribution of many cellular and extracellular systems. Nitric oxide (NO) acts on [Ca2+](c), although the mechanism of this action is unknown. We study the release and the uptake of Ca2+ in the endoplasmic reticulum and its capacitative entry in human lymphomonocytes in the presence of the NO donor S-nitrosocysteine (CysNO) at low (16 microM) and at high (160 microM) concentrations by measuring the [Ca2+](c) by the Fura 2-AM method. Thapsigargin (TG), which inhibits sarco-endoplasmic reticulum Ca2+-ATPase (SERCA), and nifedipine (NIF), which blocks the Ca2+ release from intracellular stores, are used to clarify the effects of NO on calcium movements. In the absence of extracellular Ca2+, CysNO decreases basal [Ca2+](c), whereas TG increases it as the result of SERCA inhibition. This effect of TG diminishes in the presence of the NO donor. In the presence of extracellular Ca2+(capacitative entry conditions), CysNO does not influence Ca2+ entry but reduces the toxic effects of TG connected to the increase of [Ca2+](c) in these conditions. The effect of NIF is, up to a certain extent, similar to that of CysNO, although the mechanisms of action of the two agents do not seem related. We conclude that CysNO participates in [Ca2+](c) homeostasis by stimulating the movement of the ion from the cytosol to other compartments.

Soil Selenium (Se) Biofortification Changes the Physiological, Biochemical and Epigenetic Responses to Water Stress in Zea mays L. by Inducing a Higher Drought Tolerance.

Requiring water and minerals to grow and to develop its organs, Maize (Zea mays L.) production and distribution is highly rainfall-dependent. Current global climatic changes reveal irregular rainfall patterns and this could represent for maize a stressing condition resulting in yield and productivity loss around the world. It is well known that low water availability leads the plant to adopt a number of metabolic alterations to overcome stress or reduce its effects. In this regard, selenium (Se), a trace element, can help reduce water damage caused by the overproduction of reactive oxygen species (ROS). Here we report the effects of exogenous Se supply on physiological and biochemical processes that may influence yield and quality of maize under drought stress conditions. Plants were grown in soil fertilized by adding 150 mg of Se (sodium selenite). We verified the effects of drought stress and Se treatment. Selenium biofortification proved more beneficial for maize plants when supplied at higher Se concentrations. The increase in proline, K concentrations and nitrogen metabolism in aerial parts of plants grown in Se-rich substrates, seems to prove that Se-biofortification increased plant resistance to water shortage conditions. Moreover, the increase of SeMeSeCys and SeCys2 forms in roots and aerial parts of Se-treated plants suggest resistance strategies to Se similar to those existing in Se-hyperaccumulator species. In addition, epigenetic changes in DNA methylation due to water stress and Se treatment were also investigated using methylation sensitive amplified polymorphism (MSAP). Results suggest that Se may be an activator of particular classes of genes that are involved in tolerance to abiotic stresses. In particular, PSY (phytoene synthase) gene, essential for maintaining leaf carotenoid contents, SDH (sorbitol dehydrogenase), whose activity regulates the level of important osmolytes during drought stress and ADH (alcohol dehydrogenase), whose activity plays a central role in biochemical adaptation to environmental stress. In conclusion, Se-biofortification could help maize plants to cope with drought stress conditions, by inducing a higher drought tolerance.

Identification of CDC25 as a Common Therapeutic Target for Triple-Negative Breast Cancer.

CDK4/6 inhibitors are effective against cancer cells expressing the tumor suppressor RB1, but not RB1-deficient cells, posing the challenge of how to target RB1 loss. In triple-negative breast cancer (TNBC), RB1 and PTEN are frequently inactivated together with TP53. We performed kinome/phosphatase inhibitor screens on primary mouse Rb/p53-, Pten/p53-, and human RB1/PTEN/TP53-deficient TNBC cell lines and identified CDC25 phosphatase as a common target. Pharmacological or genetic inhibition of CDC25 suppressed growth of RB1-deficient TNBC cells that are resistant to combined CDK4/6 plus CDK2 inhibition. Minimal cooperation was observed in vitro between CDC25 antagonists and CDK1, CDK2, or CDK4/6 inhibitors, but strong synergy with WEE1 inhibition was apparent. In accordance with increased PI3K signaling following long-term CDC25 inhibition, CDC25 and PI3K inhibitors effectively synergized to suppress TNBC growth both in vitro and in xenotransplantation models. These results provide a rationale for the development of CDC25-based therapies for diverse RB1/PTEN/TP53-deficient and -proficient TNBCs.

Noncanonical Fungal Autophagy Inhibits Inflammation in Response to IFN-γ via DAPK1.

Defects in a form of noncanonical autophagy, known as LC3-associated phagocytosis (LAP), lead to increased inflammatory pathology during fungal infection. Although LAP contributes to fungal degradation, the molecular mechanisms underlying LAP-mediated modulation of inflammation are unknown. We describe a mechanism by which inflammation is regulated during LAP through the death-associated protein kinase 1 (DAPK1). The ATF6/C/EBP-ß/DAPK1 axis activated by IFN-γ not only mediates LAP to Aspergillus fumigatus but also concomitantly inhibits Nod-like receptor protein 3 (NLRP3) activation and restrains pathogenic inflammation. In mouse models and patient samples of chronic granulomatous disease, which exhibit defective autophagy and increased inflammasome activity, IFN-γ restores reduced DAPK1 activity and dampens fungal growth. Additionally, in a cohort of hematopoietic stem cell-transplanted patients, a genetic DAPK1 deficiency is associated with increased inflammation and heightened aspergillosis susceptibility. Thus, DAPK1 is a potential drugable player in regulating the inflammatory response during fungal clearance initiated by IFN-γ.

Activity of olive oil phenols on lymphomonocyte cytosolic calcium.

Phenols, present in the Mediterranean diet, have antioxidant properties and are free radical scavengers; however, the molecular mechanisms of their beneficial effects are not yet fully understood. The level of cytosolic calcium ([Ca2+]i) is an important signal also in nonexcitable cells, including immune cells, and regulates fundamental processes. In this paper, we determine [Ca2+]i in human lymphomonocytes incubated with two olive oil phenols: 3,4-(dihydroxyphenyl)ethanol and p-(hydroxyphenyl)ethanol. Both tested phenols increase [Ca2+]i in a dose-dependent way. This effect is antagonized by nifedipine and is noticeable both in the presence and in the absence of calcium in the extracellular medium.

Synthesis of new indole-based bisphosphonates and evaluation of their chelating ability in PE/CA-PJ15 cells.

Bisphosphonates are the most important class of antiresorptive agents used against osteoclast-mediated bone loss, and, more recently, in oncology. These compounds have high affinity for calcium ions (Ca(2+)) and therefore target bone mineral, where they appear to be internalized selectively by bone-resorbing osteoclasts and inhibit osteoclast function. They are extensively used in healthcare, however they are affected by severe side effects; pharmacological properties of bisphosphonates depend on their molecular structure, which is frequently the cause of poor intestinal adsorption and low distribution. In this work we synthesized six novel bisphosphonate compounds having a variably substituted indole moiety to evaluate their extra- and intracellular calcium chelating ability in PE/CA-PJ15 cells. Preliminary in silico and in vitro ADME studies were also performed and the results suggested that the indole moiety plays an important role in cell permeability and metabolism properties.

Fusion of prostasomes to human spermatozoa stimulates the acrosome reaction.

OBJECTIVE: To determine the effect of the fusion of prostasomes to spermatozoa on the acrosome reaction. DESIGN: In vitro study of human spermatozoa. SETTING: Healthy volunteers in an academic research environment. PATIENT(S): Healthy volunteer men, 25 to 35 years old. INTERVENTION(S): Human semen was fractionated into spermatozoa and prostasomes. Fusion of prostasome to spermatozoa was performed at pH 5.5. Progesterone (1 microM) was added when required. MAIN OUTCOME MEASURE(S): Evaluation of the acrosome reaction by fluorescence microscopy. RESULTS(S): The percentage of spontaneously acrosome-reacted cells was very low unless the Ca(2+)-ionophore A 23187 was added. The treatment of spermatozoa with 1 microM of progesterone scarcely affected the acrosome reaction; a pretreatment in conditions permitting fusion increased it. The addition of progesterone to prostasome-fused spermatozoa further increased the extent of the acrosome reaction. CONCLUSION(S): The H(+)-dependent fusion with prostasomes makes spermatozoa more sensitive to the effect of progesterone on acrosome-reaction induction.

Effect of FSH and progesterone on human spermatozoa cytosolic calcium.

Ejaculated spermatozoa must undergo a number of modifications before fertilizing the oocyte: among these the capacitation and the acrosome reaction. Calcium signals play an essential role in these functional and structural modifications. Mature spermatozoa have few organelles and a very small cytoplasmic volume but maintain the homeostasis of [Ca(2+)](c) with great accuracy. We study Ca(2+) mobilization in human spermatozoa exposed to FSH and progesterone by measuring the [Ca(2+)](c) with the FURA-2AM method and report for the first time that the exposure to FSH (up to 98ng/ml) produced an increase of [Ca(2+)](c) to an extent comparable to that observed with 1muM progesterone. FSH and progesterone increase the spermatozoa [Ca(2+)](c) by acting primarily on calcium entry from the external medium. The effects of the two hormones on [Ca(2+)](c) were similar but not identical; the pre-treatment of progesterone blocks the effects of FSH, but not vice-versa. The increase of [Ca(2+)](c) due to FSH was more sensitive to nifedipine (VOCCs inhibitor) than that of progesterone. The effects of these hormones on calcium homeostasis may be relevant for sperm activation.

Cytosolic calcium levels in spermatozoa are modulated differently in healthy subjects and patients with varicocele.

OBJECTIVE: To study parameters connected to fertility in the semen of patients with varicocele. DESIGN: We examine the ability of spermatozoa obtained from patients with varicocele to respond with an increase of cytosolic Ca2+ ([Ca2+]i) to some stimuli that are connected with spermatozoa activation. SETTING: An academic research environment. PATIENT(S): Ten healthy volunteer donors and 10 patients affected by II or III grade left varicocele. INTERVENTION(S): Spermatozoa and prostasomes (vesicles of prostatic origin obtained from semen) were prepared according to standard procedures. Spermatozoa were stimulated with 1 microM P. The [Ca2+]i was evaluated with the FURA II method. MAIN OUTCOME MEASURE(S): The level of [Ca2+]i. RESULT(S): In resting cells, the level of [Ca2+]i was 120 +/-15 nmol/L (10 determinations). This value increases by > or =100 nmol/L upon stimulation with P. No difference was observed between spermatozoa obtained from healthy donors or from patients with varicocele. S-nitrosocysteine, a nitric oxide donor, and the fusion between spermatozoa and prostasomes increased the effect of P on [Ca2+]i in control spermatozoa but not in spermatozoa obtained from patients with varicocele. CONCLUSION(S): Different responsiveness of varicocele patients' spermatozoa to S-nitrosocysteine and/or to fusion with prostasomes may be among the possible causes of reduced fertility.

Role of cholesterol, DOTAP, and DPPC in prostasome/spermatozoa interaction and fusion.

Prostasomes are membranous vesicles present in ejaculated human semen. They are very rich in cholesterol and can interact with spermatozoa. Their physiological roles are still under study. Prostasomes were mixed with liposomes prepared from various lipids, such as N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium (DOTAP), DOTAP/1,2-dipalmytoyl-sn-glycero-3-phosphorylcholine (DPPC, 4:1 molar ratio) and DOTAP/cholesterol (4:1, molar ratio) at different pH values (5-8). The mixing of the lipid phases (fusion) was determined by the relief of octadecyl rhodamine B chloride (R(18)) self-quenching and the radii of the vesicles, by light scattering measurements. The mixing of lipids and the radii of prostasomes were both influenced by the addition of liposome, although in a different manner. The ability of prostasomes (modified by previous treatment with liposomes) to transfer lipid to spermatozoa was also measured. Pretreatment with DOTAP decreased the phenomenon and addition of DPPC abolished it. On the other hand, pretreatment of prostasomes with DOTAP/cholesterol liposomes did not affect the transfer of lipid between prostasome and spermatozoa. Therefore, the ability of vesicles to fuse (or, at least, to exchange the lipid component) was affected by the enrichment in either natural or artificial lipid. This may open new possibilities for the modulation of spermatozoa capacitation and acrosome reaction.

Antagonism between olive oil phenolics and nitric oxide on lymphomonocyte cytosolic calcium.

Some biological actions of olive oil phenolics (inhibition of platelet aggregation, decrease of LDL-oxidation, inhibition of bacterial growth and hypertensive action) have been attributed to NOS stimulation in endothelial cells through an increase of cytosolic calcium, notwithstanding the scavenging activity of phenolics on NO and superoxide. In this paper, we determine the concentration of cytosolic calcium in human lymphomonocytes incubated with high concentrations of NO-donors (CysNO) and we evaluate the effects of olive oil phenolics on this parameter. CysNO induces a marked decrease of cytosolic calcium; both olive oil phenolics oppose this action of CysNO. The effects of phenolics and CysNO are independent and additive.

Electrochemical assay for determining nitrosyl derivatives of human hemoglobin: nitrosylhemoglobin and S-nitrosylhemoglobin.

Nitric oxide (NO) is an important biological regulator. It can bind to heme iron and form NO+, involved in the synthesis of S-nitrosothiols (-SNOs). NO reacts with human hemoglobin (Hb) to produce the derivatives: S-nitrosylhemoglobin (-SNOHb) and nitrosylhemoglobin (HbNO). At neutral pH values, free NO does not react directly with the -SH groups of Hb. The reductive nitrosylation of Fe(III) heme upon reaction with NO has long been studied, but it is not yet completely known. To quantify the reaction of NO with Hb, we developed a new, sensitive (nanomolar concentration range) electrochemical assay to selectively measure HbNO and -SNOHb. The assay also allows the monitoring of free NO during the reaction with human Fe(III)Hb and Fe(II)HbO(2).

Electrochemical determination of nitric oxide and of its derivatives.

Nitric oxide (NO) is one of the simplest odd electron species. Furthermore, it is relatively hydrophobic, which is consistent with its role as a diffusible intracellular messenger or as an immune effector. NO is generated in biological systems and plays important roles as a regulatory molecule. The main problem in NO analysis is its extreme reactivity; in aerated water solution it is transformed into nitrite and nitrate, inactive biological forms. Moreover, it may lose an electron forming the NO(+) ion, involved in the synthesis of nitrosothiols (RSNOs). The main problems encountered in the analytical determination of free NO and of RSNOs in biological systems are the low stability and the very low concentration of these compounds. The determination of nitrates and nitrites may also be difficult when their concentration is in the nmolar range. We describe an electrochemical assay for the determination in the same sample of free NO and of its derivatives in nmolar range. Owing to its high sensitivity, the procedure could also be applied to environmental analyses.