Investigation of Ternary Complex Formations of Polyacrylic Acid with Bovine Serum Albumin in the Presence of Metal Ions by Fluorescence and Dynamic Light Scattering Measurements

In this paper, the complex formation of bovine serum albumin (BSA) and polyacrylic acid (PAA) in the presence metal ions at pH = 7 has been examined by using fluorescence and dynamic light scattering measurements. It has been observed that the most stable complexes of polyacrylic acid and bovine serum albumin have occurred in the presence of copper(II) ions. The other ions have the ability to form weak complexes between polyions and bovine serum albumin. To prior characterizing the interaction between bovine serum albumin and polyacrylic acid, the dynamic light scattering technique have been applied to determine the intensity-size distributions of the solutions of bovine serum albumin, polyacrylic acid, and ternary mixtures containing various molar ratios of bovine serum albumin to polyacrylic acid (the molar ratios of bovine serum albumin to polyacrylic acid has been taken equal to 0.5, 1.0, 1.5, 2.0 and 2.5) prepared at different molar ratios of copper(II) ions/acrylic acid unit. When the molar ratio of copper(II) ions to acrylic acid in the ternary mixtures has been lower than and equals to 0.3, two peaks have been observed in the curves of the intensity-size distributions due to contents of free bovine serum albumin and ternary complexes of polyacrylic acid-copper(II)-bovine serum albumin whereas when the molar ratio of copper(II) ions to acrylic acid equals to 0.4, the hydrodynamic diameter has pointed out only one peak. This result indicates that soluble and stable ternary complexes has occurred when the molar ratio of copper(II) ions to acrylic acid has been taken equal to 0.4.     

Determination of antioxidant activity of various extracts of <Emphasis Type="Italic">Parmelia saxatilis</Emphasis>

The work was conducted with the purpose to evaluate antioxidant activity of Parmelia saxatilis (PS) by different analytical methods. Water and methanol were used as solvents and antioxidative effects were measured by a ferric thiocyanate method (FTC) and thiobarbituric acid test (TBA). The antioxidant activity increased with the increasing amount of extracts (from 50 to 250 μg) added to linoleic acid emulsion. The methanol extract of PS exhibited high antioxidative activity that was not significantly (P < 0.05) different from α-tocopherol, while aqueous extracts of PS showed low antioxidative activity. Similar trends of antioxidant activity were observed using either the FTC or TBA methods. Antioxidant activity, reducing power, free radical scavenging (DPPH^·), superoxide anion radical scavenging, metal chelating and hydrogen peroxide scavenging activities of PS extracts showed dose dependence and increased with concentration of PS extract. The results obtained in the present study indicate that the PS might be a potential source of natural antioxidant.     

Effects of a modified zeolite on P and N processes and fluxes across the lake sediment–water interface using core incubations

A new locally produced P-inactivation agent, Z2G1, was tested on sediment cores from Lake Okaro, New Zealand, for phosphorus (P) removal efficacy and any non-target side effects prior to a whole lake trial to manage internal P loading. Z2G1 is a granular product which settles rapidly, and was designed as a sediment capping material. It is a modified zeolite which acts as a carrier for the aluminium (Al)-based P-binding agent. It was found to have a high affinity for P and did not release Al into the water column. Continuous-flow incubation study results showed that a thin layer of Z2G1 (~2 mm) could completely block the release of P from the sediment under aerobic and anoxic conditions, and remove P from the overlying water in contact with the capping layer. The Z2G1 capping layer neither released metals itself nor did it induce the release of metals from the sediments, and the zeolite substrate absorbed arsenic and mercury from the geothermally influenced Lake Okaro sediments. In general, zeolites are strong cation absorbers and the zeolite substrate of Z2G1 absorbed ammoniacal nitrogen, making it the only sediment capping material to actively remove both P and N. There were, however, indications of a suppression effect on microbial denitrification by the Z2G1 capping layer under aerobic conditions. Overall, the Z2G1 sediment capping material is a highly effective P-inactivation agent which might be a useful material for managing internal P loads in eutrophic lakes.     

Aminoethoxydiphenyl Borate and Flufenamic Acid Inhibit Ca<Superscript>2+</Superscript> Influx Through TRPM2 Channels in Rat Dorsal Root Ganglion Neurons Activated by ADP-Ribose and Rotenone

Exposure to oxidative stress causes health problems, including sensory neuron neuropathy and pain. Rotenone is a toxin used to generate intracellular oxidative stress in neurons. However, the mechanism of toxicity in dorsal root ganglion (DRG) neurons has not been characterized. Melastatin-like transient receptor potential 2 (TRPM2) channel activation and inhibition in response to oxidative stress, ADP-ribose (ADPR), flufenamic acid (FFA) and 2-aminoethoxydiphenyl borate (2-APB) in DRG neurons are also not clear. We tested the effects of FFA and 2-APB on ADPR and rotenone-induced TRPM2 cation channel activation in DRG neurons of rats. DRG neurons were freshly isolated from rats and studied with the conventional whole-cell patch-clamp technique. Rotenone, FFA and 2-APB were extracellularly added through the patch chamber, and ADPR was applied intracellularly through the patch pipette. TRPM2 cation currents were consistently induced by ADPR and rotenone. Current densities of the neurons were higher in the ADPR and rotenone groups than in control. The time courses (gating times) in the neurons were longer in the rotenone than in the ADPR group. ADPR and rotenone-induced TRPM2 currents were totally blocked by 2-APB and partially blocked by FFA. In conclusion, TRPM2 channels were constitutively activated by ADPR and rotenone, and 2-APB and FFA induced an inhibitory effect on TRPM2 cation channel currents in rat DRG neurons. Since oxidative stress is a common feature of neuropathic pain and diseases of sensory neurons, the present findings have broad application to the etiology of neuropathic pain and diseases of DRG neurons.     

Biomolecular Structure and Composition Changes in the Root System of Long-Lipped Serapias (Serapias vomeracea) After In Vitro Chitosan and Plant Growth Regulator Treatments

In the current study, effects of chitosan oligomers (CHI-OM) with different polymerization degrees (DP) between 2 and 15, and polymeric chitosan (CHI-P) with a DP of 70 were compared with kinetin (KIN), 6-benzylaminopurine (BAP), indole-3-butyric acid (IBA), indole-3-acetic acid (IAA), and jasmonic acid (JAS) on the structure and composition of several biomolecules in the root system of Serapias vomeracea. Evaluation of molecular alterations in the root system of S. vomeracea through an infrared spectroscopic approach provided insight into the differentiation between action mechanisms of chitosan and commonly used plant growth regulators. The results revealed that CHI-P and JAS treatments at low concentrations might enhance the lignin content in the cell walls. Also, JAS, CHI-OM, and CHI-P treatments enhanced cell wall lignification. The water-associated cellulose content of the cell walls was affected by the DP of chitosan. Membrane lipid stabilization and protein content were enhanced after CHI-P, JAS, and KIN treatments, while BAP and CHI-OM treatments triggered lipid, protein, and cell wall polysaccharide synthesis. In particular, CHI-OM treatment also enhanced rhamnogalacturonan and β-galactan content as well as xyloglucans and glucomannans, while the auxin treatments had a similar impact only on glucomannan content. These findings suggest that chitosan may show either purine-based cytokinin-like or lipid-based jasmonic acid-like activity in the root system of S. vomeracea. Additionally, depending on its degree of polymerization, the effects of chitosan may vary on root system development in S. vomeracea.

     

Mutations in the <Emphasis Type="Italic">S</Emphasis> gene region of hepatitis B virus genotype <Emphasis Type="Italic">D</Emphasis> in Turkish patients

The S gene region of the hepatitis B virus (HBV) is responsible for the expression of surface antigens and includes the ‘a’-determinant region. Thus, mutation(s) in this region would afford HBV variants a distinct survival advantage, permitting the mutant virus to escape from the immune system. The aim of this study was to search for mutations of the S gene region in different patient groups infected with genotype D variants of HBV, and to analyse the biological significance of these mutations. Moreover, we investigated S gene mutation inductance among family members. Forty HBV-DNA-positive patients were determined among 132 hepatitis B surface antigen (HbsAg) carriers by the first stage of seminested PCR. Genotypes and subtypes were established by sequencing of the amplified S gene regions. Variants were compared with original sequences of these serotypes, and mutations were identified. All variants were designated as genotype D and subtype ayw3. Ten kinds of point mutations were identified within the S region. The highest rates of mutation were found in chronic hepatitis patients and their family members. The amino acid mutations 125 (M → T) and 127 (T → P) were found on the first loop of ‘a’-determinant. The other consequence was mutation inductance in a family member. We found some mutations in the S gene region known to be stable and observed that some of these mutations affected S gene expression.     

Zinc, copper and iron concentrations in cerebral cortex of male rats exposed to formaldehyde inhalation

Retrospective cohort studies and clinical findings have suggested effects of formaldehyde exposure on the central nervous system in anatomists, embalmers and pathologists. On the other hand, harmful effects of formaldehyde inhalation on the nervous system are not well documented. The concentrations of elements such as zinc, copper and iron within the cerebral cortex indicate whether physiological conditions are maintained. In this study, adult male albino Wistar rats were exposed to formaldehyde at different concentrations (0; 6.1; 12.2 mg x m(-3)) and during different periods of time (subacute-subchronic), and body weights were recorded weekly. Zinc, copper and iron concentrations were measured in the parietal cortex using atomic absorption spectrometry after wet ashing. We conclude that subacute or subchronic exposure to formaldehyde may cause growth retardation and alter zinc, copper and iron levels in the cerebral cortex.     

Model-based process analysis of partial nitrification efficiency under dynamic nitrogen loading

In this study, the ammonia removal efficiency for high ammonia-containing wastewaters was evaluated via partial nitrification. A nitrifier biocommunity was first enriched in a fill-and-draw batch reactor with a specific ammonium oxidation rate of 0.1 mg NH₄ ⁻-N/mg VSS.h. Partial nitrification was established in a chemostat at a hydraulic retention time (HRT) of 1.15 days, which was equal to the sludge retention time (SRT). The results showed that the critical HRT (SRT) was 1.0 day for the system. A maximum specific ammonium oxidation rate was achieved as 0.280 mg NH₄ ⁻-N/mg VSS.h, which is 2.8-fold higher than that obtained in the fill-and-draw reactor, indicating that more adaptive and highly active ammonium oxidizers were enriched in the chemostat. Dynamic modeling of partial nitrification showed that the maximum growth rate for ammonium oxidizers was found to be 1.22 day⁻¹. Modeling studies also validated the recovery period as 10 days.