Taxonomic Status of the Okhotsk Lumpsucker Eumicrotremus ochotonensis (Cyclopteridae,Cottoidei) with Redescription of E. derjugini

Journal of Ichthyology - The species status is justified for the Okhotsk lumpsucker Eumicrotremus ochotonensis based on the morphological characters. The differences from the closely related...     

Theoretical and experimental studies of the radiative properties of matter at high energy densities and their application to the problems of inertial confinement fusion

The paper presents the results of theoretical and experimental studies of the radiative properties of plasmas produced by heating and compression of various materials to high energy densities. The specific features of the theoretical plasma model known as the ion model, which is used to calculate the radiative characteristics of plasmas of complex chemical composition, are discussed. The theoretical approach based on this model is applied to the plasma produced during the explosion of the X-pinch wires. The theoretical estimate of the radiation efficiency is compared with the experimental data on the total energy yield from an X-pinch made of two different wires (NiCr and Alloy 188). The radiative characteristics of (C12 H16 O8) and (C8 H12 O6) plasmas are calculated for the temperature diagnostics of plasmas produced from porous targets employed in inertial confinement fusion experiments with the use of laser radiation and heavy-ion beams.     

On the mechanism of shrinkage-induced potassium influx in rat and human erythrocytes.

The rates of 86Rb influx into human and rat erythrocytes were studied in media of various tonicity. At sucrose concentrations below 0.3 mol/l, the ouabain-insensitive, furosemide-inhibited component of influx increased in rat but not in human erythrocytes; this may be explained by a rise in the rate of Na+, K+, Cl-- and/or K+, Cl-cotransport. An increase in osmolarity resulted in a reduction of this as well as of the ouabain and furosemide-insensitive component in rat erythrocytes. At the same conditions a drastic inhibition of Na+, K(+)-pump occurred both in rat and human erythrocytes. We failed to observe a lag-phase in the activation of the cotransport in rat erythrocytes; i. e. the process of activation parallels the shrinkage of cells. In rat erythrocyte ghosts, the shrinkage-induced stimulation of the cotransport was lost, and the direction of their osmotic reaction (inhibition of transport pathways) was similar to that in human erythrocyte ghosts. It is suggested that the mechanism of volume regulation of ion transport in intact cells involves a step of physical amplification via a change in interactions between the protein carcass and the lipid bilayer.     

Otolith shape lends support to the sensory drive hypothesis in rockfishes

The sensory drive hypothesis proposes that environmental factors affect both signalling dynamics and the evolution of signals and receivers. Sound detection and equilibrium in marine fishes are senses dependent on the sagittae otoliths, whose morphological variability appears intrinsically linked to the environment. The aim of this study was to understand if and which environmental factors could be conditioning the evolution of this sensory structure, therefore lending support to the sensory drive hypothesis. Thus, we analysed the otolith shape of 42 rockfish species (Sebastes spp.) to test the potential associations with the phylogeny, biological (age), ecological (feeding habit and depth distribution) and biogeographical factors. The results showed strong differences in the otolith shapes of some species, noticeably influenced by ecological and biogeographical factors. Moreover, otolith shape was clearly conditioned by phylogeny, but with a strong environmental effect, cautioning about the use of this structure for the systematics of rockfishes or other marine fishes. However, our most relevant finding is that the data supported the sensory drive hypothesis as a force promoting the radiation of the genus Sebastes. This hypothesis holds that adaptive divergence in communication has significant influence relative to other life history traits. It has already been established in Sebastes for visual characters and organs; our results showed that it applies to otolith transformations as well (despite the clear influence of feeding and depth), expanding the scope of the hypothesis to other sensory structures.     

Molecular mechanisms of photoreception. V. Reconstitution of a sodium channel on an artificial lipid membrane modified by bovine rod outer segment components

An attempt is made to reconstitute the Na+-conductivity elements of rod outer segment (ROS) plasma membrane on the artificial lipid membrane (ALM). ALM were modified by preparation with bovine ROS plasma membrane fragments. Discrete fluctuations of the ALM conductivity were observed at addition of this preparation to the ALM bathing solutions to a final concentration of 0.1--1.0 microgram/ml. The magnitude of these fluctuations was about 25 pS at 140 mM NaCl. The modified ALM possessed preferentially the Na+-conductivity, which was at least five times as great as that for K+ or Li+. The modified ALM showed practically no conductivity for Cl-. The Na+-channels were voltage-dependent. The Na+-channels were "sensitive to visible light" at some experimental conditions. The optimal conditions were obtained for reconstitution of Na+-channel on the ALM. The temporal and termal stabilities of the modified preparation were investigated. It was shown that the frequency of the modified ALM conductivity fluctuations are dependent on temperature and on lipids composition of ALM. The data obtained in our work are in a good agreement with the results of electrophysiological studies of photoreceptor cells. It may be indicated, that the investigated ALM contains the Na+-channel of the ROS plasma membranes. It is suggested that the reconstituted system will be useful for studying the principles of regulation of ROS plasma membrane sodium conductivity and the nature of a mediator in a photoreceptor transduction mechanism.     

Features of the spatial distribution and size structure of the Pacific lamprey <Emphasis Type="Italic">Lampetra tridentata</Emphasis> in the North Pacific

Results of long-term research on the spatial and vertical distribution of the Pacific lamprey Lampetra tridentata (Richardson, 1836) (the family Petromyzontidae) in the North Pacific, and data on its size structure are submitted. It was shown, that L. tridentate reached its greatest number in the Bering Sea. The maximum concentration of the Pacific lamprey was observed all year round about Navarin Cape, in the Koryak shelf area, at the East Aleutian Islands and at the west coast of the USA, which, apparently, spoke of the increased number of its prey there. On the bottom, the Pacific lamprey was the most numerous at depths of less than 500 m, and in the pelagic, in the upper 100-meter layer. The length of individuals varied in catches from 12 up to 85 cm. The existence of several size groups may indicate that the Pacific lamprey spend several years in the sea. No correlation was revealed between the length of body and fishing depth. The correlations between body length and body weight, body length and condition factor were analyzed. Seasonal dynamics of these parameters were considered.     

Apoptosis in serum-deprived vascular smooth muscle cells: Evidence for cell volume-independent mechanism

Shrinkage is the earliest hallmark of cells undergoing apoptosis. This study examines the role of this phenomenon in the onset of vascular smooth muscle cell (VSMC) apoptosis triggered by growth factor withdrawal. In hyperosmotic media, VSMC showed the same amplitude of shrinkage but were more resistant to apoptosis than endothelial, epithelial and immune system cells. As with growth factor withdrawal, apoptosis in hyperosmotically-shrunken VSMC was sharply potentiated by transfection with E1A-adenoviral protein and was suppressed by activation of cAMP signaling as well as by the pan-caspase inhibitor z-VAD.fmk. Both cell shrinkage and apoptosis in VSMC-E1A treated with hyperosmotic medium were potentiated under sustained Na+, K+ pump inhibition with ouabain that was in contrast to inhibition of apoptosis documented in ouabain-treated, serum-deprived cells. After 1-hr incubation in serum-deprived medium, VSMC-E1A volume declined by approximately 15%. Transfer from hypotonic to control medium decreased VSMC-E1A volume by approximately 25% without any induction of apoptosis. Neither swelling in hyposmotic medium nor dissipation of the transmembrane gradient of K+ and major organic osmolytes protected serum-deprived VSMC-E1A from apoptosis. Thus, our results show that similarly to immune system, endothelial and epithelial cells, extensive VSMC shrinkage in hyperosmotic medium leads to the development of apoptosis. In contrast to hyperosmotic medium, the modest cell volume decrease occurring in serum-deprived VSMC does not contribute to triggering of the apoptotic machinery.