Ulva rigida (Ulvales,Chlorophyta) tank culture as biofilters for dissolved inorganic nitrogen from fishpond effluents

Ulva rigida was cultivated in 7501 tanks at different densities with direct and continuous inflow (at 2, 4, 8 and 12 volumes d^–1) of the effluents from a commercial marine fishpond (40 metric tonnes, Tm, of Sparus aurata, water exchange rate of 16 m³ Tm^–1) in order to assess the maximum and optimum dissolved inorganic nitrogen (DIN) uptake rate and the annual stability of the Ulva tank biofiltering system. Maximum yields (40 g DW m^–2 d^–1) were obtained at a density of 2.5 g FW 1^–1 and at a DIN inflow rate of 1.7 g DIN m^–2 d^–1. Maximum DIN uptake rates were obtained during summer (2.2 g DIN M^–2 d^–1), and minimum in winter (1.1 g DIN m^–2 d^–1) with a yearly average DIN uptake rate of 1.77 g DIN m^–2 d^–1 At yearly average DIN removal efficiency (2.0 g DIN m^–2 d^–1, if winter period is excluded), 153 m² of Ulva tank surface would be needed to recover 100% of the DIN produced by 1 Tm of fish.Abbreviations DIN= dissolved inorganic nitrogen (NH _inf4 ^sup+ + NO _inf3 ^sup– + NO _inf2 ^sup– ); - FW= fresh weight; - DW= dry weight; - PFD= photon flux density; - V= DIN uptake rate     

The CO2-concentrating mechanism in a starchless mutant of the green unicellular alga Chlorella pyrenoidosa

The CO₂-concentrating mechanism (CCM) was induced in the green unicellular alga Chlorella when cells were transferred from high (5% CO₂) to low (0.03%) CO₂ concentrations. The induction of the CCM correlated with the formation of a starch sheath specifically around the pyrenoid in the chloroplast. With the aim of clarifying whether the starch sheath was involved in the operation of the CCM, we isolated and physiologically characterized a starchless mutant of Chlorella pyrenoidosa, designated as IAA-36. The mutant strain grew as vigorously as the wild type under high and low CO₂ concentrations, continuous light and a 12 h light/12 h dark photoperiod. The CO₂ requirement for half-maximal rates of photosynthesis [K_0.5(CO₂)] decreased from 40 μM to 2–3 μM of CO₂ when both wild type and mutant were switched from high to low CO₂. The high affinity for inorganic carbon indicates that the IAA-36 mutant is able to induce a fully active CCM. Since the mutant does not have the pyrenoid starch sheath, we conclude that the sheath is not involved in the operation of the CCM in Chlorella cells.     

Intracellular carbonic anhydrase of Chlamydomonas reinhardtii.

An intracellular carbonic anhydrase (CA; EC 4.2.1.1) was purified to homogeneity from a mutant strain of Chlamydomonas reinhardtii (CW 92) lacking a cell wall. Intact cells were washed to remove periplasmic CA and were lysed and fractionated into soluble and membrane fractions by sedimentation. All of the CA activity sedimented with the membrane fraction and was dissociated by treatment with a buffer containing 200 mM KCI. Solubilized proteins were fractionated by ammonium sulfate precipitation, anionic exchange chromatography, and hydrophobic interaction chromatography. The resulting fraction had a specific activity of 1260 Wilbur-Anderson units/mg protein and was inhibited by acetazolamide (50% inhibition concentration, 12 nM). Final purification was accomplished by the specific absorption of the enzyme to a Centricon-10 microconcentrator filter. A single, 29.5-kD polypeptide was eluted from the filter with sodium dodecyl sulfate-polyacrylamide gel electrophoresis sample buffer, and a 1.5 M ammonium sulfate eluate contained CA activity. In comparison with human CA isoenzyme II, the N-terminal and internal amino acid sequences from the 29.5-kD polypeptide were 40% identical with the N-terminal region and 67% identical with an internal conserved region. Based on this evidence, we postulate that the 29.5-kD polypeptide is an internal CA in C. reinhardtii and that the enzyme is closely related to the alpha-type CAs observed in animal species.     

The Memory Effect of Microdischarges in the Barrier Discharge in Airflow

Plasma Physics Reports - The paper devoted to the research of the microdischarge dynamics in the dielectric barrier discharge. The discharge between rail electrodes in airflow along the electrodes...     

Growth and cell wall properties of two wheat cultivars differing in their sensitivity to aluminum stress

The present study was conducted to investigate the cell wall properties in two wheat (Triticum aestivum L.) cultivars differing in their sensitivity to Al stress. Seedlings of Al-resistant, Inia66 and Al-sensitive, Kalyansona cultivars were grown in complete nutrient solutions for 4 days and then subjected to treatment solutions containing Al (0, 50 microM) in a 0.5 mM CaCl(2) solution at pH 4.5 for 24 h. Root elongation was inhibited greatly by the Al treatment in the Al-sensitive cultivar compared to the Al-resistant cultivar. The Al-resistant cultivar accumulated less amount of Al in the root apex than in the Al-sensitive cultivar. The contents of pectin and hemicellulose in roots were increased with Al stress, and this increase was more conspicuous in the Al-sensitive cultivar. The molecular mass of hemicellulosic polysaccharides was increased by the Al treatment in the Al-sensitive cultivar. The increase in the content of hemicellulose was attributed to increase in the contents of glucose, arabinose and xylose in neutral sugars. Aluminum treatment increased the contents of ferulic acid and p-coumaric acid especially in the Al-sensitive cultivar by increasing the activity of phenylalanine ammonia lyase (PAL, EC 4.3.1.5). Aluminum treatment markedly decreased the beta-glucanase activity in the Al-sensitive cultivar, but did not exert any effect in the Al-resistant cultivar. These results suggest that the modulation of the activity of beta-glucanase with Al stress may be involved in part in the alteration of the molecular mass of hemicellulosic polysaccharides in the Al-sensitive cultivar. The increase in the molecular mass of hemicellulosic polysaccharides and ferulic acid synthesis in the Al-sensitive cultivar with Al stress may induce the mechanical rigidity of the cell wall and inhibit the elongation of wheat roots.     

Synthesis and antibacterial activity of substituted flavones, 4-thioflavones and 4-iminoflavones

Synthesis of flavones, 4-thioflavones and 4-iminoflavones was carried out with the substitution of variable halogens, methyl, methoxy and nitro groups in the A, B and AB rings of the respective compounds and we also report here their antibacterial activity. Most of the synthesized compounds were found to be active against Escherichia coli, Bacillus subtilis, Shigella flexnari, Salmonella aureus, Salmonella typhi and Pseudomonas aeruginosa. Activity of 4-thioflavones and 4-iminoflavones was found to be higher than that of their corresponding flavone analogues. Investigated compounds having substituents like F, OMe and NO2 at 4'-position in ring-B exhibited enhanced activity and the presence of electronegative groups in the studied compounds showed a direct relationship to the antibacterial activity.     

Bioengineering functional copolymers. XIV. Synthesis and interaction of poly(N-isopropylacrylamide-co-3,4-dihydro-2H-pyran-alt-maleic anhydride)s with SCLC cancer cells

Novel antitumor active functional polymers with supramacromolecular structures were synthesized by a complex-radical terpolymerization of N-isopropylacrylamide (NIPAm), 3,4-dihydro-2H-pyran (DHP), and maleic anhydride (MA) with 2,2'-azoisobisbutyronitrile as a radical initiator in 1,4-dioxane at 65°C under nitrogen atmosphere. The structure and composition of terpolymers were investigated by (1)H ((13)C) NMR spectroscopy. Interaction of terpolymers with human lung small cell carcinoma (SCLC) were investigated by using different methods such as cytotoxicity, statistical, apoptotic and necrotic cell indexes, double staining and caspase-3 immunostaining, light and fluorescence inverted microscopy analyses. Investigations into structure, composition, and antitumor activity relationships revealed that terpolymers containing a combination of ionisable amide-pyran linkages and H-bonded carboxylic groups exhibited higher cytotoxicity. It was observed that terpolymer with nearly alternating structure provides a maximum concentration of ionisable and H-bonded antitumor sites, and therefore, exhibits higher in vitro cytotoxicity, apoptotic and necrotic effects towards SCLC cancer cells.     

Novel compound from Trachyspermum ammi (Ajowan caraway) seeds with antibiofilm and antiadherence activities against Streptococcus mutans: a potential chemotherapeutic agent against dental caries

Aim: The objective of this study was to isolate and characterize the active compound from Trachyspermum ammi seeds, exhibiting antibiofilm activity against Streptococcus mutans, a major causal organism of dental caries. Methods and Results: Purification of the active compound from the seeds was performed by silica gel chromatography, and spectroscopic methods (FTIR, NMR and MS) were employed for its identification and structure determination. Antibiofilm and antiadherence activities of the active compound against S. mutans were analysed. Confocal microscopy was performed to visualize the effect of the compound on biofilm structure of S. mutans. Around 50% reduction was observed in adherence at 39·06 μg ml^?1 and in biofilm at 78·13 μg ml^?1. It was found effective against adherent cells of S. mutans, reduced water‐insoluble glucan synthesis and inhibited the reduction in pH. Confocal microscopy revealed scattered cells at sub‐MIC concentration of the compound, resulting in distorted biofilm architecture in contrast to clustered cells seen in control. Conclusion: This study revealed a novel compound, a naphthalene derivative, isolated first time from T. ammi seeds with antibiofilm activity against S. mutans. Significance and Impact of the Study: Trachyspermum ammi represents an interesting source of a novel compound, (4aS, 5R, 8aS) 5, 8a‐di‐1‐propyl‐octahydronaphthalen‐1‐(2H)‐one, with a great potential to be used as a therapeutic agent against dental caries.