Carbohydrate metabolism parameters in the thick-billed murre (Uria lomvia) infested with Alcataenia armillaris (Cestoda: Dilepididae)

Some aspects of carbohydrate metabolism in noninfested thick-billed murres (Uria lomvia) and those infested with the tapeworm Alcataenia armillaris (Cestoda: Dilepididae) are reported. The findings demonstrate that the intestinal invasion by A. armillaris causes a drop in the activity of digestive enzymes (glycosidases and sacharase) and decreases blood glucose levels and glycogen content in the liver. The main reasons underlying changes in avian carbohydrate metabolism in cestode invasion are suggested.     

Dynamics of the states of heart rate regulation during 24-h monitoring

An attempt was made to classify the heart rate (HR) regulation states observed during 24-h monitoring of HR variability parameters in patients with essential hypertension and coronary heart disease. A continuous chain of nonoverlapping 5-min intervals was studied, and the cardiointerval mode, the spectral powers in the ranges of respiratory and first-order slow waves, their ratio, and the total spectral power were determined for each interval. Combinations of HR characteristics obtained for 5-min intervals were classified using nonparametric clustering methods. The standard clustering always revealed a limited number (8–13) of classes of HR regulation states. For every patient, the classes of states were numbered and their chronological sequence was studied with a mathematical apparatus for analyzing Markov chains. A set of state-to-state transitions significantly differing in frequency from random transitions was revealed for every patient.Translated from Fiziologiya Cheloveka, Vol. 31, No. 2, 2005, pp. 85–89.Original Russian Text Copyright © 2005 by Dzizinskii, Kuklin, Mikhalevich, Rozhkova.     

Isolation and analysis of amplified cDNA fragments during detection of unknown polymorphisms with temperature modulated heteroduplex chromatography

A procedure for isolation of polymerase chain reaction (PCR) fragments from an automated system for DNA fragment analysis is described. The technique is used for screening of unknown mutations or polymorphisms. Fragments are isolated during the analysis from the system by an automated unit for high-throughput projects or manually when working with a few samples.     

Fractal nature of chromatin organization in interphase chicken erythrocyte nuclei: DNA structure exhibits biphasic fractal properties

Arrangement of chromatin in intact chicken erythrocyte nuclei was investigated by small angle neutron scattering. The scattering spectra have revealed that on the scales between 15 nm and 1.5 microm the interior of the nucleus exhibited properties of a mass fractal. The fractal dimension of the protein component of cell nucleus held constant at approximately 2.5, while the DNA organization was biphasic, with the fractal dimension slightly higher than 2 on the scales smaller than 300 nm and approaching 3 on the larger scales.     

Activity of digestive enzymes of thick-billed guillemot (<Emphasis Type=Italic>Uria lomvia</Emphasis>) and common guillemot (<Emphasis Type=Italic>U. aalge</Emphasis>) invaded by cestodes

Activities of digestive enzymes (proteases, carbohydrases, acid and alkaline phosphatases) are determined in intestinal mucosa of the thick-billed and common guillemots. Comparative analysis of the obtained results is performed for non-infested and for birds infested by cestodes. It has been established that at infestation by cestode Alcataenia armillaris (Cestoda: Tetrabothriidae), activities of carbohydrase and alkaline phosphatase in intestinal mucosa of the thick-billed guillemot decreases. Parasitizing of cestodes Tetrabothrius jaegerskieldi (Cestoda: Tetrabothriidae) in intestine induces a decrease of saccharase activity. There is studied kinetics of desorption of enzymes from digestive-transport surfaces of the bird intestine. Peculiarities of firmness of enzyme fixation are established on the surface of intestinal mucosa of invaded guillemots. According to the obtained data, a decrease of the carbohydrase activities in intestine of infested guillemots is likely to be due to absorption of a part of enzymes hydrolyzing carbohydrates on the surface of cestodes.     

Detection of new double-membrane structures in native mitochondria by the method of small-angle neutron scattering

The structure of mitochondrial cristae has been studied for the first time by the method of small-angle neutron scattering. Experiments were performed on intact (functioning) mitochondria from rat liver. Mitochondrial cristae are usually considered to be folds of the inner membrane with arbitrary variable intermembrane distances. Under conditions of low-amplitude swelling, mitochondrial cristae transformed into double-membrane structures with a distance of 190 Å between the central planes of the membranes. The formation of double-membrane structures and their structural parameters did not depend on the method for inducing swelling which was accomplished either by placing the mitochondria into a hypotonic medium or through the opening of nonspecific pores.     

Conformational flexibility of RecA protein filament: transitions between compressed and stretched states

RecA protein is a central enzyme in homologous DNA recombination, repair and other forms of DNA metabolism in bacteria. It functions as a flexible helix-shaped filament bound on stretched single-stranded or double-stranded DNA in the presence of ATP. In this work, we present an atomic level model for conformational transitions of the RecA filament. The model describes small movements of the RecA N-terminal domain due to coordinated rotation of main chain dihedral angles of two amino acid residues (Psi/Lys23 and Phi/Gly24), while maintaining unchanged the RecA intersubunit interface. The model is able to reproduce a wide range of observed helix pitches in transitions between compressed and stretched conformations of the RecA filament. Predictions of the model are in agreement with Small Angle Neutron Scattering (SANS) measurements of the filament helix pitch in RecA::ADP-AlF(4) complex at various salt concentrations.     

Study of α-Crystallin Structure by Small Angle Neutron Scattering with Contrast Variation

The structure of the oligomeric protein α-crystallin from bovine eye lens was investigated by small-angle neutron scattering (SANS) with contrast variation. Based on the SANS curves, the match point for α-crystallin (43% D²O) and its average scattering length density at this point (2.4•1010 cm^-2) were evaluated. The radius of gyration and the distance distri- bution functions for α-crystallin were calculated. On the basis of these calculations, it was concluded that α-crystallin is characterized by homogeneous distribution of scattering density in the domains inaccessible for water penetration, and all polypeptide subunits in α-crystallin oligomers undergo equal deuteration. The latter indicates that all α-crystallin subunits are equally accessible for water and presumably for some other low molecular weight substances. These conclusions on the α-crystallin structure (homogeneous distribution of scattering density and equal accessibility of all subunits for low molecular weight substances) should be taken into account when elaborating a-crystallin quaternary structure models.     

Consortia in Aquatic Ecosystems of the Transbaikalia

A survey in the basin of the Khilok River (a right tributary of the Selenga River) in 1999–2002 allowed us to reveal and describe the consortia of cyanobacteria Stratonostoc linckia f. linckia and Stratonostoc verrucosum, green alga Cladophora aegagropila, stonewort Nitella opaca, water moss Fontinalis sp., and duckweed Lemna trisulca. The relationship between the consort organisms and edificator plants can become the limiting factor in these communities. The long-term studies of the benthic communities of the Arakhlei Lake demonstrate the significance of the consortium approach in the long-term prediction of changes in the lake ecosystem.