Comparative analysis of photosynthetic and respiratory parameters in the psychrophilic unicellular green alga , cultured in indoor and outdoor photo-bioreactors.

Effect of temperatures and illumination of temperate winter on photosynthesis and respiration was studied in the psychrophilic microalgae, (Trebouxiophyceae). Outdoor and indoor algal cultures were compared. Photosynthetic as well as respiration rates increased as light and temperature increased, until 35 °C, more in outdoor than in indoor cells, in agreement with the calculated values.

Sulphate and chloride-dependent potassium transport in human erythrocytes are affected by crude venom from nematocysts of the jellyfish Pelagia noctiluca.

Background: It has been reported that biologically active compounds extracted from Cnidaria venom may induce damage by oxidative stress. Erythrocytes are constantly exposed to oxidative stresses, which can contribute to sulphydril (SH-) group oxidation and cell membrane deformability accompanied with activation of K-Cl co-transport and inhibition of anion transport. In this regard, Band 3 protein is responsible for mediating the electroneutral exchange of chloride (Cl(-)) for bicarbonate (HCO3(-)), particularly in erythrocytes, where it is the most abundant membrane protein.

Effects of lead chloride on human erythrocyte membranes and on kinetic anion sulphate and glutathione concentrations.

Our study concerns the effects of exposure to lead chloride on the morphology, K(+) efflux, SO(4)(-) influx and GSH levels of the human erythrocyte. Blood was collected in heparinized tubes and washed three times. The cells were suspended at 3% hematocrit and incubated for 1 h at 25°C in a medium containing increasing concentrations of lead chloride (0, 0.

Temperature dependence of nitrate reductase in the psychrophilic unicellular alga Koliella antarctica and the mesophilic alga Chlorella sorokiniana.

Temperature responses of nitrate reductase (NR) were studied in the psychrophilic unicellular alga, Koliella antarctica, and in the mesophilic species, Chlorella sorokiniana. Enzymes from both species were purified to near homogeneity by Blue Sepharose (Pharmacia, Uppsala, Sweden) affinity chromatography and high-resolution anion-exchange chromatography (MonoQ; Pharmacia; Uppsala, Sweden). Both enzymes have a subunit molecular mass of 100 kDa, and K.

Glucose-6P dehydrogenase in Chlorella sorokiniana (211/8k): an enzyme with unusual characteristics.

In Chlorella sorokiniana (211/8k), glucose-6 phosphate dehydrogenase (G6PDH-EC 1.1.1.

Glutamate synthase activities and protein changes in relation to nitrogen nutrition in barley: the dependence on different plastidic glucose-6P dehydrogenase isoforms.

In barley (Hordeum vulgare L. var. Nure), glutamate synthesis and the production of reducing power by the oxidative pentose phosphate pathway (OPPP) are strictly correlated biochemical processes.

Temperature responses of growth, photosynthesis, respiration and NADH: nitrate reductase in cryophilic and mesophilic algae.

•  Temperature effects on growth, photosynthesis, respiration and nitrate reductase (NR) were studied in the cryophilic algae Koliella antarctica and 'Chlorella'saccharophila, and in the mesophilic Chlorella sorokiniana. •  Growth rate was measured as increase in optical density. Photosynthesis at saturating light and respiration in darkness were measured as O exchange.

Ammonium assimilation by young plants of Hordeum vulgare in light and darkness: effects on respiratory oxygen consumption by roots.

Barley plants (Hordeum vutgare L.) grown for 10 d in nitrogen-free hydroponic culture, after a rapid initial phase absorbed supplied NH4 (+) at a constant rate of 15.1 ±1.

Ionic strength dependence of formation constants-XVIII. The hydrolysis of iron(III) in aqueous KNO(3) solutions.

The hydrolysis of iron(III) was studied potentiometrically at different ionic strengths in KNO(3) aqueous solutions, at 25 degrees C, to determine the dependence of hydrolysis constants on ionic strength (nitrate media), to check the existence of nitrate-ferric ion interactions, and to confirm the formation of high polymeric species. Under the experimental conditions 0.03 I (KNO(3)) 1M, 0.

Protonation and complex formation constants of 3-amino-1,2,4-triazole in NaCl and CaCl(2) media at different temperatures and ionic strengths.

The protonation of 3-amino-1,2,4-triazole was studied potentiometrically (glass electrode) in sodium chloride and calcium chloride solutions, 0.13 I 0.92M, at 10, 25, 37 and 45 degrees .

The determination of formation constants of weak complexes by potentiometric measurements: experimental procedures and calculation methods.

Experimental and calculation procedures for the study of weak complexes by the pH-measurement technique are described. An algorithm for the calculation of formation constants, together with a computer program in FORTRAN and BASIC versions, is reported. The problems of studying weak interactions are discussed.

Ionic strength dependence of formation constants-V Protonation constants of some nitrogen-containing ligands at different temperatures and ionic strengths.

The protonation constants of 2,2'-bipyridyl, 1,10-phenanthroline, 1,3-diaminopropane, l-histidine and histamine have been determined potentiometrically, in the temperature range 10-40 degrees and at ionic strengths ranging from 0.04 to 1 (potassium chloride). The dependence of the protonation constants on ionic strength is described by a simple general equation.

Depression of nitrate reductase in the presence of excess ammonium in a unicellular alga growing under conditions of phosphate limitation.

Chemostat cultures of the unicellular alga Cyanidium caldarium have shown that under conditions of phosphate limitation nitrate reductase is completely derepressed even in cells growing in a large excess of ammonium, but that it occurs mainly in a catalytically inactive form. It is hypothesized that phosphate limitation contributes to maintaining intracellular level of glutamine suitable to stimulate inactivation but not repression of nitrate reductase. It is not excluded that in addition to variations in the intracellular level of glutamine, there are other metabolic events of the cell by which repression and inactivation of nitrate reductase could be differently influenced.

Ionic strength dependence of formation constants-I Protonation constants of organic and inorganic acids.

The protonation constants of formic, acetic, benzoic, oxalic, phthalic, maleic, malonic, succinic, dl-malic, dl-tartaric, aminoacetic, citric, nitrilotriacetic, ethylenediaminetetra-acetic, sulphuric and orthophosphoric acids have been determined from pH measurements, in tetraethylammonium iodide solution, at various ionic strengths in the range 0.01-1.0M (for phosphoric and sulphuric acids 0.

Active and inactive nitrate reductase. Effects of mild treatment with denaturing agents of protein.

Nitrate reductase (NAD(P)H:nitrate oxidoreductase, EC 1.6.6.

A non-linear least-squares approach to the refinement of all parameters involved in acid-base titrations.

A non-linear least-squares computer program has been written for the refinement of the parameters involved in potentiometric acid-base titrations. The program ACBA (ACid-BAse titrations) is applicable under quite general conditions to solutions containing one or more acids or bases. The method of refinement used gives the program several advantages over the other programs described previously.

Studies on utilization of 2-ketoglutarate, glutamate and other amino acids by the unicellular alga Cyanidium caldarium.

Two strains of Cyandium caladarium which possess different biochemical and nutritional characteristics were examined with respect to their ability to utilize amino acids or 2-ketoglutarate as substrates. One strain utilizes alanine, glutamate or aspartate as nitrogen sources, and glutamate, alanine, or 2-ketoglutarate as carbon and energy sources for growth in the dark. The growth rate in the dark on 2-ketoglutarate is almost twice as high or higher than that on glutamate or alanine.

Observations on enzymes of ammonia assimilation in two different strains of Cyanidium caldarium.

Two strains of Cyanidium caldarium, one able to utilize nitrate as a substrate, and the other not, were tested for the presence of enzymes of ammonia assimilation. The nitrate-assimilating strain exhibits glutamate dehydrogenase activity. By contrast, the other strain lacks glutamate dehydrogenase; it possesses high alanine dehydrogenase and L-alanine aminotransferase activities which suggest that this strain may incorporate ammonia through reductive amination of pyruvate and may form glutamate from 2-ketoglutarate by a transamination reaction with alanine.

Electron donors and inhibitors of nitrate reductase from Cyanidium caldarium.

Studies on nitrate reductase (NAD(P)H:nitrate oxidoreductases EC 1.6.6.