The hydrogen (H₂) cycle associated with the dinitrogen (N₂) fixation process was studied in laboratory cultures of the marine cyanobacterium Crocosphaera watsonii. The rates of H₂ production and acetylene (C₂H₂) reduction were continuously measured over the diel cycle with simultaneous measurements of fast repetition rate fluorometry and dissolved oxygen. The maximum rate of H₂ production was c...

Hormonal control of the initial step in hepatic gluconeogenesis from pyruvate was examined following acute administration of epinephrine, glucagon, or cortisol to adult rats. After hormonal treatment of the animals, the mitochondria were isolated for the study of pyruvate metabolism. When pyruvate and bicarbonate were the only substrates provided, mitochondrial fixation of carbon dioxide and pr...

During 198 1 we examined the diel variations of nitrogen fixation in Lake Valencia, Venezuela. Four species of heterocyst-bearing blue-green algae were common but subdominant in the phytoplankton. In samples taken from and incubated at 0.5 m, the rate of nitrogen fixation per unit volume of water was lowest at night (~6% of the maximum daytime rate), increased from dawn until early afternoon, a...

background and purpose: phenol and derivatives are common pollutants of drinking water which are blamed for crucial adverse effects such as poisoning, cancer, and malformation. in this study, an activated carbon of miswak’s root (mr) was used for the removal of phenol from aqueous solutions as a low-cost and high surface adsorbent. materials and methods: adsorption experiments were then conduct...

ucb-1 (pistacia atlantica × p. integrima) is a commercial rootstock for pistachio in some pistachio plantations across the world. this rootstock is very new in iran and recently, it has been used commercially in some plantations due to its high growth. propagation of this rootstock by tissue culture results in many limitations such as shoot tip necrosis (stn) and a low proliferation rate. there...

While the reductive pentose phosphate cycle is responsible for the fixation of most of the carbon in the biosphere, it has several natural substitutes. In fact, due to the characterization of three new carbon fixation pathways in the last decade, the diversity of known metabolic solutions for autotrophic growth has doubled. In this review, the different pathways are analysed and compared accord...

Mixing of seawater subjects phytoplankton to fluctuations in photosynthetically active radiation (400-700 nm) and ultraviolet radiation (UVR; 280-400 nm). These irradiance fluctuations are now superimposed upon ocean acidification and thinning of the upper mixing layer through stratification, which alters mixing regimes. Therefore, we examined the photosynthetic carbon fixation and photochemica...

A carbon-paste electrode (CPE) chemically modified with the N-4,4'-azodianiline(ferrocenyl Schiff base) complex and multi wall carbon nanotubes (ADAFCNTE) was used as a highly sensitive electrochemical sensor for determination of trace amounts of atenolol. The oxidation peak potentials in cyclic voltammogram of ADAFCNTE occurred around 550 mV vs Ag/AgCl (at pH 6.0) while this peak potential at ...

Previous studies of photosynthetic carbon fixation in the marine alga Gonyaulax have shown that the reaction rates in vivo vary threefold between day and night but that the in vitro activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), which catalyzes the rate-limiting step in this process, remains constant. Using protein gel blotting, we confirm that Rubisco protein levels are...