Release of phosphate from calcium phosphates by rhizosphere products

Wheat plants were shown to be more efficient than maize or pea in phosphate uptake from [³²P]-labelled synthetic hydroxyapatite over a 24 h period. Each wheat plant produced on average 0.58 mg of water-soluble rhizoshpere products (a combination of root exudates and microbial products in the rhizosphere) during 12 days growth in sand. The rhizosphere products released phosphate from calcium phosphates.The dissolution of phosphate was associated with a negatively-charged fraction (obtained by ion-exchange chromatography) and with a u.v.-absorbing fraction (obtained by gel-filtration chromatography on Sephadex G-10) of the rhizosphere products. The release of phosphate from calcium phosphates by these active fractions or the crude rhizosphere products was associated with a drop in pH of the mineral suspensions compared with controls.     

Does 2-ketogluconate chelate calcium in the pH range 2.4 TO 6.4?

The dissolution of synthetic hydroxyapatite was studied as a function of pH in the presence of 10 mM 2-ketogluconate, acetate, citrate, and EDTA. In the pH range 5.7–7.7, the relative effectiveness for the dissolution of hydroxyapatite increased in the order 2-ketogluconate ? g acetate < citrate < EDTA. The dissociation constants for gluconic acid (pK_a = 3.41 at μ = 0.2, 25°C) and 2-ketogluconic acid (pK_a = 2.66, at μ = 0.2, 25°C) were measured potentiometrically and used to determine the 1:1 stability constant for the corresponding calcium complexes. The observed calcium-stability constant for the gluconate ion (log K₁₁ = 1.19 at μ = 0.2, 25°C) is in accord with an earlier determination made under similar conditions, however, the calcium stability constant for the 2-ketogluconate ion, which has not previously been reported was found to be less than or equal to the experimental error in the determination (log K₁₁ < 0 at μ = 0.2, 25°C). The negligible value for the calcium stability constant for 2-ketogluconate, confirms the dissolution observations and refutes previous qualitative assumptions in the literature suggesting that 2-ketogluconic acid is an effective chelating agent for calcium ions. It was concluded that 2-ketogluconic, the major acid component of wheat-seedling rhizosphere products is one of the strongest monobasic carboxylic acids and as such acts as a readily available source of hydrogen ions for the dissolution of hydroxyapatite. This dissolution does not involve chelation of calcium ions.     

Modulation of Lipopolysaccharide Stimulated Nuclear Factor kappa B Mediated iNOS/NO Production by Bromelain in Rat Primary Microglial Cells

Background:

Microglial cells act as the sentinel of the central nervous system .They are involved in neuroprotection but are highly implicated in neurodegeneration of the aging brain. When over-activated, microglia release pro-inflammatory factors, such as nitric oxide (NO) and cytokines, which are critical in eliciting neuroinflammatory responses associated with neurodegenerative diseases. This study examined whether bromelain, the pineapple-derived extract, may exert an anti-inflammatory effect in primary microglia and may be neuroprotective by regulating microglial activation.

Methods:

Following the isolation of neonatal rat primary microglial cells, the activation profile of microglia was investigated by studying the effects of bromelain (5, 10, 20, and 30 µg/ml) on the levels of NO, inducible nitric oxide synthase (iNOS), and nuclear factor kappa B (NF-κB) in microglia treated with lipopolysaccharide (LPS) (1 µg/ml). Data were analyzed using Student''s t-test. P values less than 0.05 were considered to be statistically significant, compared with the LPS-treated group without bromelain.

Results:

Results showed that pretreatment of rat primary microglia with bromelain, decreased the production of NO induced by LPS (1 µg/ml) treatment in a dose-dependent manner. Bromelain (30 µg/ml) also significantly reduced the expression of iNOS at mRNA level and NF-κB at protein level. Moreover, the study of mitochondrial activity in microglia indicated that bromelain had no cytotoxicity at any of the applied doses, suggesting that the anti-inflammatory effects of bromelain are not due to cell death.

Conclusion:

Bromelain can be of potential use as an agent for alleviation of symptoms in neurodegenerative diseases.     

Characterization of rhizosphere products especially 2-ketogluconic acid

Examination of rhizosphere products of wheat seedlings using a variety of Chromatographie techniques established that 2-ketogluconic acid was the only acid present in significant amounts. Elemental analysis of crystallized potassium 2-ketogluconate isolated from the rhizosphere products and data obtained by X-ray diffraction, i.r. spectrometry and specific rotation determinations confirmed the identification of the 2-ketogluconic acid. Spectrophotometric and specific rotation measurements showed that 2-ketogluconic acid represented about 20% of the rhizosphere products. Furthermore, the 2-ketogluconic acid was present in fractions of rhizosphere products shown to release phosphate from calcium phosphates. Pure 2-ketogluconic acid released phosphate from apatite rock, di- and tri-calcium phosphates. In each case there was an associated decrease in pH of the suspensions compared with controls.About 38% of the rhizosphere products was carbohydrate, and glucose and fructose were the dominant free sugars present. Since 2-ketogluconic acid is known to be a product of microbial action on glucose and the organisms involved occur in the rhizosphere it is likely that the 2-ketogluconic acid was produced from glucose in the rhizosphere.     

The effect of Rosa damascena essential oil on the amygdala electrical kindling seizures in rat

We investigated the effect of Rosa damascena Mill, essential oil on the development of induced amygdala kindling seizures. Male Wistar rats were implanted with one tripolar and two monopolar electrodes in right basolateral amygdala and dura surface, respectively. The control group was injected solvent of essential oil and two experimental groups were injected 750 and 1000 mg kg(-1) of essential oil (ip), 30 min before a daily kindling stimulation. The number of stimulations required for the first appearance of seizure stages was significantly larger in two experimental groups than in control group. Mean after discharge duration was significantly different and essential oil reduced the increase of after discharge duration. Mean after discharge amplitude was also shorter in the groups treated with essential oil than in control group. Duration time for 5th stage of seizure at fully-kindled rats was significantly shorter in two experimental groups than control group. These results suggest that Rosa damascena essential oil significantly retarded the development of seizure stages and possesses the ability to counteract kindling acquisition. The flavonoids of Rosa damascena may act via GABAA receptors as previous studies have proposed for flavonoids of other medicinal plants. More detailed studies are recommended to define the effective component(s) of Rosa on different types of epilepsy.     

Silk degumming using microwave irradiation as an environmentally friendly surface modification method

Degumming is a surface modification process of natural fibers such as silk. In this paper, the feasibility of degumming of Persian silk by microwave irradiation as an environmentally friendly surface modification technique was investigated. The physical properties of the degummed silk were investigated. The effectiveness of parameters such as microwave irradiation time, surfactant, soap, and degumming time on silk degumming were studied. The evaluation of the data was carried out through the measurement of the weight loss, strength, and elongation of the samples. The scanning electron microscope images were obtained for degummed silk samples. The findings of this research support the potential production of new environmentally friendly textile fibers using microwave irradiation.     

Pico Level Monitoring of Silver with Modified Hexagonal Mesoporous Compound (MCM-41) and Inductively Coupled Plasma Atomic Emission Spectrometry

A rapid method for the extraction and monitoring of picogram level of silver ions using uniform silanized mesopor (MCM-41) modified by a thiocompound and inductively coupled plasma atomic emission spectrometry (ICP-AES) is presented. The preconcentration factor of the method is 500, and detection limit of the technique for silver is 6.5 pg/ml. The time and the efficiency of the extraction, pH and flow rate, type and minimum amount of acid for stripping of silver from modified MCM-41 was tested. The break through volume of the method was found 2500 ml. The maximum capacity the modified MCM-41 was found to be 11.0 ± 1.2 μg of Ag⁺/mg modified MCM-41.     

The Effect of Vermicompost on Transformation Rate of Available P Applied as Chemical Fertilizer in a Calcareous Clay Soil

The effects of vermicompost (VC) (0% and 1% w/w) on treated calcareous clay soil with 0 and 50 mg phosphorus (P) kg^?1 as calcium phosphate [Ca(H₂PO₄)₂.H₂O] was investigated. The soil samples were incubated for 7, 30, 60, 120, and 150 d at 25 ± 1°C and Olsen-P was measured after each incubation time. Results showed that Olsen-P increased 36% and 38% after VC addition in treated soil with 0 and 50 mg P kg^?1, respectively. Recovery of Olsen-P in treated soils with VC, combined fertilizer VC + P, and fertilizer P was 42%, 42%, and 17%, respectively. The rate coefficient in treated soils with fertilizer, VC, and combined fertilizer VC + P was 0.033, 0.026, and 0.023 mg kg^?1 d^?1/2, respectively. It seems that the process that leads to the decrease in available P in amended soils, is controlled by P diffusion into sorption sites in micropores of aggregates.