Evidence of free fatty acid interdigitation in stratum corneum model membranes based on ceramide [AP] by deuterium labelling

This research paper provides direct evidence concerning the localisation of free fatty acids in stratum corneum lipid model membranes. We employed partially deuterated free fatty acids to gain further information about the assembly of a stratum corneum lipid model membrane based on a ceramide of the phytosphingosine-type (ceramide [AP]) with particular respect to the position of the deuterated groups of the free fatty acids. The application of behenic-22,22,22-d₃-acid and cerotic-12,12,13,13-d₄-acid confirmed that the short-chain ceramide [AP] forces the longer-chained free fatty acids to incorporate into the bilayer created by ceramide [AP]. The ceramide [AP] molecules determine the structural assembly of this model membrane and obligate the long-chain free fatty acids to either arrange inside this formation or to separate as a fatty acid rich phase.     

Localization of antigenic determinants using monoclonal antibodies and alpha-NH2-terminal labeling of polypeptide chains

A method for localization of antigenic determinants in a polypeptide chain of unknown primary structure was proposed. A protein is modified at NH2-terminal and epsilon-NH2-groups of lysine residues with maleic anhydride and then is subjected to partial enzymatic cleavage. Newly formed NH2-terminal groups are tagged with radioiodinated Bolton--Hunter's reagent. The labeled fragments of the antigen are then demaleylated. Comparison of the two longest labeled fragments, only one of which still binds monoclonal antibody, makes it possible to define the location of the antigenic determinant along the polypeptide chain. The method was tested on the bovine tryptophanyl-tRNA synthetase using earlier prepared monoclonal antibodies against this enzyme.     

Interaction of human thrombin I fragment, prethrombin I, and alpha-thrombin with tissue thromboplastin]

The binding of 125I-labeled prothrombin fragment I. prethrombin I and alpha-thrombin to native and papain-treated tissue thromboplastin in the presence of CaCl2 of EDTA was studied. The experimental curves plotted in the Scatchard coordinates testify to the presence in thromboplastin of two types of fragment I binding sites: those with a high (Kd = 7.6 x 10(-6) M) and moderate (Kd = 1.3 x 10(-8) M) binding affinity. The parameters of fragment I binding and their changes reproduced, for the most part, the mode of prothrombin binding observed in previous studies. The experimental results provide indirect evidence in favour of a hydrophobic role of Ca(2+)-dependent binding of prothrombin fragment I to thromboplastin. The binding of prethrombin I was nonspecific and Ca(2+)-independent, whereas alpha-thrombin showed a relatively high level of nonspecific electrostatic binding which was competitively inhibited by Ca2+. Thromboplastin proteins interacted (both directly and in a Ca(2+)-independent fashion) with all the prothrombin derivatives under study.     

Selective self-synchronization of pulses in neuronal networks of the visual system

In the present study we have checked the hypothesis that the degree of pulse synchrony in neuronal pools is determined by the level of excitation of the neuronal network or its loci and that this relationship does not depend on the factor that causes the excitation. Pulse reactions of neurons in pools (2–4 cells) of cat lateral geniculate nucleus and visual cortex were registered. Neurons were excited using either visual stimuli or glutamic acid microinjections into neuronal pools. The increase of neural pool excitation level (No) regardless of the type of stimulus was shown to increase the pulse synchrony (Ns), with a correlation coefficient of 0.716 ± 0.217. One may suppose that the level of neuronal network excitation “governs” the synchrony of pulses generated by the network, i.e., neuronal networks function in compliance with the principle of self-synchronization.     

Effect of fluorine-containing ethers of permetrinic acid on inactivation kinetics of sodium influx into neuroblastoma cells (NEURO-2(alpha)]

A synthesis of a number of esters of (+/-)-cis, trans-3-(2,2-dichlorovinyl) -2,2-dimethylcyclopropanecarboxylic acid with polyfluorinated alcohols was carried out. Their effect on kinetics of inactivation of sodium current in neuroblastoma (Neuro-2a) cells by the patch-clamp technique in the whole-cell configuration was investigated.     

Distribution of Saprophytic Bacteria in the Atomic Submarine Accident Zone in Chazhma Bay, Sea of Japan

The numerical and taxonomic composition of saprophytic bacteria was studied in the atomic submarine accident zone in Chazhma Bay. With increasing depth in the epicenter of the accident zone, the mean of the ratio of bacterial taxa in the resistance series tends toward a constant. The numerical structure of the pelagic saprophytic bacterial assemblage becomes ordered as the bottom is approached. Analysis of radioactive suspended matter allowed us to obtain model distribution of numbers of all saprophytes and each taxon from the different environmental sources (sediment surface and upper layers of the sea).Original Russian Text Copyright © 2005 by Biologiya Morya, Ivanova, Gorshkova, Mikhailov, Sergeev, Gladkikh, Goryachev, Dudarev, Botsul, Mozherovsky, Slinko, Kiselev.