Red-breasted goose colonies on the Taimyr Peninsula: Factors responsible for the proximity of goose nests to nests of peregrine falcons,rough-legged buzzards,and snowy owls

Red-breasted goose colonies have been studied near Medusa Bay (73°21′N, 80°32′E), on the northwestern Taimyr Peninsula, and along the Agapa River (70°11′N, 86°15′E) down to its mouth (71°26′N, 89° 13′E), in the central Taimyr Peninsula. Red-breasted geese nesting near peregrine falcons are protected by the falcons from arctic foxes; however, they are sometimes attacked by the falcons themselves. In the colonies near peregrine falcon nests, the vast majority of goose nests were situated no farther than 100 m from the falcon nest. When food is abundant, falcons protect a larger area around their nest. The distance between the falcon nest and the surrounding goose nests is inversely related to the falcon’s activity. In years of higher falcon activity, falcons prevent red-breasted geese from nesting as close to their nest as in years of lower falcon activity. Additional stimuli are required for red-breasted geese to form colonies near rough-legged buzzard nests. The distance between snowy owl nests and red-breasted goose nests was smaller when arctic foxes were abundant than when they were scarce.     

Kinetics of NO ligation with nitric-oxide synthase by flash photolysis and stopped-flow spectrophotometry

Nitric-oxide synthase (NOS) catalyzes conversion of L-arginine to nitric oxide, which subsequently stimulates a host of physiological processes. Prior work suggests that NOS is inhibited by NO, providing opportunities for autoregulation. This contribution reports that NO reacts rapidly (ka congruent with 2 x 10(7) M-1 s-1) with neuronal NOS in both its ferric and ferrous oxidation states. Association kinetics are almost unaffected by L-arginine or the cofactor tetrahydrobiopterin. There is no evidence for the distinct two phases previously reported for association kinetics of CO. Small amounts of geminate recombination of NO trapped in a protein pocket can be observed over nanoseconds, and a much larger amount is inferred to take place at picosecond time scales. Dissociation rates are also very fast from the ferric form, in the neighborhood of 50 s-1, when measured by extrapolating association rates to the zero NO concentration limit. Scavenging experiments give dissociation rate constants more than an order of magnitude slower: still quite fast. For the ferrous species, extrapolation is not distinguishable from zero, while scavenging experiments give a dissociation rate constant near 10(-4) s-1. Implications of these results for interactions near the heme binding site are discussed.     

An integrated NAD+-dependent enzyme-functionalized field-effect transistor (ENFET) system: development of a lactate biosensor

An integrated NAD+-dependent enzyme field-effect transistor (ENFET) device for the biosensing of lactate is described. The aminosiloxane-functionalized gate interface is modified with pyrroloquinoline quinone (PQQ) that acts as a catalyst for the oxidation of NADH. Synthetic amino-derivative of NAD+ is covalently linked to the PQQ monolayer. An affinity complex formed between the NAD+/PQQ-assembly and the NAD+-cofactor-dependent lactate dehydrogenase (LDH) is crosslinked and yields an integrated biosensor ENFET-device for the analysis of lactate. Biocatalyzed oxidation of lactate generates NADH that is oxidized by PQQ in the presence of Ca2+-ions. The reduced catalyst, PQQH2, is oxidized by O2 in a process that constantly regenerates PQQ at the gate interface. The biocatalyzed formation of NADH and the O2-stimulated regeneration of PQQ yield a steady-state pH gradient between the gate interface and the bulk solution. The changes in the pH of the solution near the gate interface and, consequently, the gate potential are controlled by the substrate (lactate) concentration in the solution. The device reveals the detection limit of 1 x 10(-4) M for lactate and the sensitivity of 24+/-2 mV dec(-1). The response time of the device is as low as 15 s.     

Centric diatom algae (Centrophyceae) of ultraoligotrophic Lake Elgygytgyn and water bodies of its basin (Chukotka,Russia)

The electron microscopy study of algae from Lake Elgygytgyn and the water bodies of its basin has revealed 21 taxa of centric diatoms of specific and intraspecific ranks. Nine new species and varieties have been found, including Aulacoseira distans var. nivaloides, A. distans var. septentrionalis, Discostella guslyakovyi, which are rare for the flora of Russia; an endemic species (?) Pliocaenicus seckinae; and six interesting forms from the genus Aulacoseira identified only to the genus. The list of Centrophyceae of Beringia has been broadened.     

Estimation of the carry-over of substances by dragonflies from water bodies to land in the forest-steppe of West Siberia

The results of many years’ monitoring of the number and distribution of dragonflies in the Chany area of the Baraba forest-steppe are presented. An estimation of the biomass carry-over by dragonflies from water bodies to land ecosystems is given. The data presented provide evidence of the important role of dragonflies in the migration of substances from water bodies to land.     

Diatoms (Bacillariophyceae) in sediments of three mountain oligotrophic lakes of the Amguema River basin (Chukotka)

A diatom assemblage found in bottom sediments of mountain oligotrophic lakes in the Amguema River basin (Ervynaigytgyn, Matachingaigytgyn, Ekitiki) is presented for the first time. For each taxon, data on the occurrence in the Beringia region are given. Three new combinations are suggested.     

Effect of hyperbaric oxygenation on central hemodynamics and oxygenating function of the lungs in open-heart surgery]

The dynamics of some oxygenating pulmonary function (OPF) indices has been studied in 33 patients with coronary cardiac disease and rheumatic lesions of cardiac valves 4-6 hours after surgery in response to a single hyperbaric oxygenation (HBO) session (1.5 ata, 45 min) in the immediate postoperative period. It is found that in the presence of slight or, on the contrary, pronounced arterial hypoxemia, no significant negative OPF changes were observed. At the same time, a temporary increase in the alveolo-arterial gradient has been found in some patients. The comparison of data on the systemic blood flow with the OPF indices permits suggesting the prevalent role of the membrane component in a PaO2 decrease in patients after using assisted circulation.     

A study of interaction of carbonic anhydrase B with water and urea: II. Spin diffusion of associates of protein intermediate state at 4.2 M urea

Formation of the associates of carbonic anhydrase B (pH 5.7, 4.2 M urea, and T = 297 K) as a function of protein concentration and time clapsed after preparation of solutions was studied by nuclear magnetic resonance spectroscopy (spin diffusion method). It was demonstrated that the association was a two-stage process. The initial (fast) stage, involving the formation of persistent blocks, was independent of the time elapsed after the solution preparation. A urea concentration of 4.2 M allows the protein molecules to interact with one another to form rather small persistent blocks in combination with solvent molecules, so that the mobility of each molecule remains nearly unchanged. The final (slow) stage is time-dependent and involves the formation of large structures from the persistent blocks. It is shown that parameters G* and S*, which characterize spin diffusion (in protein and solvent, respectively) when it is excited at frequencies remote from the NMR spectral signals, are related to the size probability distribution of the solvent-protein associates and are determined by their collective properties.