Changes in the myocardium damaged by strophanthin

The mechanism of intoxication, produced with strophanthin (10 mg/kg) has been studied in myocardium of white rats. Area, perimeter and factor of form in mitochondria, ratio of the mitochondrial surface area with injured external membranes to the whole mitochondrial area, agranular sarcoplasmic network and T-system area, changes in myofilaments, Z-lines, length of sarcomeres have been estimated. Changes in succinate dehydrogenase, lactate dehydrogenase and in reduced forms of nicotinamide coenzymes activity has been investigated histochemically. Adenosine triphosphate (ATP) prevents appearance of ultrastructural and histochemical disturbances, produced with strophanthin. However, the protective effect of ATP is not sufficient. Adenosine monophosphate, penetrating across the cell membrane, is supposed to produce a greater curative effect.     

Integrated membrane systems for gas separation in biotechnology: potential and prospects

Integrated non-porous membrane systems were applied for microbial combustible gas separation processes. Methane/CO₂ mixtures of various concentrations from methane fermentation processes (biogas) were separated using a membrane-separation complex of permabsorber type into individual components of technical grade (more than 95% purity). In experiments with three-component mixtures, using a selective membrane valve with various liquid carriers, all the gases of interest (H₂, CH₄ and CO₂) were obtained at greater than 90% purity in one separation step. The perspectives for the further application of non-porous membrane separating devices for various gaseous mixtures from different microbial processes are discussed.V. Teplyakov and E. Sostina are with the A.V. Topchiev institute of Petrochemical Synthesis, Russian Academy of Sciences, Membrane Research Center, Moscow 117912, Russia. E. Sostina is also, and A. Netrusov is with the Microbiology Department, Moscow University, Moscow 119899, Russia. I. Beckman is with the Chemistry Department, Moscow University, Moscow 119899, Russia.     

Biochemical changes accompanying the long-term starvation of Micrococcus luteus cells in spent growth medium

Changes in the biochemical properties of Micrococcus luteus cells were studied during the transition to a dormant state after incubation in an extended stationary phase. The overall DNA content after 150 days of starvation was similar to its initial level, while the RNA content decreased by 50%. Total lipids and protein, phospholipids and membrane proteins declined rapidly within the first 1–10 days of starvation. After 180 days of starvation, cells contained 43% of the protein and 35% of the lipid initially present. Starvation for 120 days resulted in the loss of phosphatidylglycerol and, to some extent, of phosphatidylinositol, giving a membrane whose phospholipids consisted mainly of cardiolipin. The membrane fluidity declined during starvation, as judged by diphenyl hexatriene fluorescence anisotropy measurements. Oxidase activities declined to zero within the first 20–30 days of starvation, while the dehydrogenases and cytochromes were more stable. The activities of some cytoplasmic enzymes were lost very rapidly, while NADPH-linked isocitrate dehydrogenase had 30% of its initial activity after 120 days of starvation. For all parameters tested there were significant fluctuations during the first 10–20 days of starvation, which may reflect cryptic growth in the culture.Abbreviations MPN Most probable number - DPH Diphenyl hexatriene     

A distributed-parameter model of the myelinated human motor nerve fibre: temporal and spatial distributions of action potentials and ionic currents

 A double cable model of the myelinated human motor nerve fibre is presented. The model is based on the nodal and internodal channels in a previous, two-component model of human motor axons (Bostock et al. 1991), added to a complex extended cable structure of nodal, paranodal and internodal segments. The model assumes a high-resistance myelin sheath and a leakage pathway to the internodal axolemma via the paranodal seal resistance and periaxonal space. The parameter values of the model were adjusted to match the recordings of threshold electrotonus in human motor fibres from Bostock et al. (1991). Kirchoff ’s current law was used to derive a system of partial differential equations for the electrical equivalent circuit, and numerical integration was performed with a fixed time increment and non-uniform spatial step sizes, in accordance with the complex structure of the fibre. The model calculations provide estimates of the spatial and temporal distributions of action potentials and their transaxonal and transmyelin components, both in different segments of the fibre and at different moments during action potential propagation. The distribution of transaxonal and transmyelin currents along the fibre and their contributions from different ionic channels are also explored. Received: 14 July 1994/Accepted in revised form: 4 April 1995     

A novel approach to the analysis of the initiation of embryo development in gramineae

An in vivo model system to study the initiation of embryo development is presented. From the so-called Salmon system of wheat (alloplasmic lines with a 1BL-1RS chromosome translocation), three completely isogenic and homozygous lines were produced by selection for uniformity in about 20 selfing/backcross generations as well as between sublines of doubled haploids. The line (aestivum)-Salmon is male fertile and sexual. The lines (caudata)-Salmon and (kotschyi)-Salmon are male sterile and have a parthenogenetic capacity of about 90%. The expression of nuclear-cytoplasmic male sterility is different for the two parthenogenetic lines. The initiation of autonomous embryo development at defined developmental stages of the ovaries and the maximum degree of parthenogenesis are identical in both parthenogenetic lines as proved by the auxin test and progeny analyses. The protein patterns from ovary extracts of the three isogenic lines were identical for more than 200 spots of 2-D polyacrylamide gels, confirming their homogeneity. However, one protein (P 115.1) was found 3 days before and during anthesis only in ovaries of the parthenogenetic lines. It seems to be involved in the initiation of parthenogenesis.     

DNA reduplication cycle during chromosome polytenization in the salivary gland cells of Chironomus thummi larvae. III. The determination of the duration of the DNA synthesis period

The duration of DNA synthesis in the salivary gland cells of Chironomus thummi larvae of the IV instar was determined by means of autoradiography and cytophotometry. Cells of different levels of ploidy differ in the duration of their DNA synthesis period. The tS of 2(10)c and 2(11)c cells was equal to 17 and 22 hours, respectively. The doubling of DNA content of the chironomid salivary gland cells leads to a 1.3 time increase in the duration of S-phase.     

Electron microscopic study of the differentiation of decidual cells. I. The ultrastructure of large decidual cells in the antimesometrial portion of the rat decidua

The large decidual cells (LDC) of the antimesometrial part of decidua in rats of 7-9 days of gestation were studied by electron microscope. The decidual tissue has an epithelium-like pattern of organization. The apical surface of LDC is facing the pericapillar space making numerous villi. Lateral surfaces of these cells maintain close contact with each other by means of zona adhaerens, gap junctions, spot desmosomes and simple junctions. Accumulation of electron dense granules measuring from 0.05 to 0.3 mkm is seen in the apical parts of LDC. The Golgi complex and rough endoplasmic reticulum are much developed. The material of rough endoplasmic reticulum is denser than the cell matrix. Disperse chromatin is seen in the nucleus, whereas the granular component is dominanting in the nucleolus. It is concluded that the LDC may have a high metabolic activity, and that the secretion is a mode of fulfilling specific functions of LDC.