Peculiarities of the Seasonal Biology of Ectoparasites of the Genus <Emphasis Type="Italic">Spinturnix</Emphasis> von Heyden, 1826 (Mesostigmata: Gamasina: Spinturnicidae) in the Boreal Zone of the Palearctic Region

The most complete data on the peculiarities of seasonal biology of gamasid mites of the genus Spinturnix, which are ectoparasites of bats of the boreal zone of the Old World, are presented. Data on the dynamics of the sex and age structure of superpopulations of parasites throughout the year are presented; the infestation of various bat species is analyzed, and the factors affecting it are discussed. The main differences between the life cycles of the boreal and subboreal Spinturnicidae mites were revealed.     

Bumetanide-sensitive Ion Fluxes in Vascular Smooth Muscle Cells: Lack of Functional Na+, K+, 2 Cl− Cotransport

To examine the involvement of Na⁺,K⁺,2Cl⁻ cotransport in monovalent ion fluxes in vascular smooth muscle cells (VSMC), we compared the effect of bumetanide on ⁸⁶Rb, ³⁶Cl and ²²Na uptake by quiescent cultures of VSMC from rat aorta. Under basal conditions, the values of bumetanide-sensitive (BS) inward and outward ⁸⁶Rb fluxes were not different. Bumetanide decreased basal ⁸⁶Rb uptake by 70–75% with a K _i of ∼0.2–0.3 μm. At concentrations ranging up to 1 μm, bumetanide did not affect ³⁶Cl influx and reduced it by 20–30% in the range from 3 to 100 μm. In contrast to ⁸⁶Rb and ³⁶Cl influx, bumetanide did not inhibit ²²Na uptake by VSMC. BS ⁸⁶Rb uptake was completely abolished in Na⁺- or Cl⁻-free media. In contrast to ⁸⁶Rb, basal BS ³⁶Cl influx was not affected by Na⁺ _o and K⁺ _o . Hyperosmotic and isosmotic shrinkage of VSMC increased ⁸⁶Rb and ³⁶Cl influx to the same extent. Shrinkage-induced increments of ⁸⁶Rb and ³⁶Cl uptake were completely abolished by bumetanide with a K _i or ∼0.3 μm. Shrinkage did not induce BS ⁸⁶Rb and ³⁶Cl influx in (Na⁺ or Cl⁻)- and (Na⁺ or K⁺)-depleted media, respectively. In the presence of an inhibitor of Na⁺/H⁺ exchange (EIPA), neither hyperosmotic nor isosmotic shrinkage activated ²²Na influx. Bumetanide (1 μm) did not modify basal VSMC volume and intracellular content of sodium, potassium and chloride but abolished the regulatory volume increase in isosmotically-shrunken VSMC. These data demonstrate the absence of the functional Na⁺,K⁺,2Cl⁻ cotransporter in VSMC and suggest that in these cells basal and shrinkage-induced BS K⁺ influx is mediated by (Na⁺ _o + Cl⁻ _o )-dependent K⁺/K⁺ exchange and Na⁺ _o -dependent K⁺,Cl⁻ cotransport, respectively. Received: 30 January 1996/Revised: 20 May 1996     

The effect of neurotropic agents on evoked potentials of the association and projection regions of the cat neocortex]

Intensive non-specific inactivation of the cortex by means of its local cooling, in the cat anasthetized with nembutal, blocks in a similar way the early component of associative responses (ECAR) in the parietal area and the primary responses (PR) in the projection areas. In the case of local application of neurotropic drugs possessing specific and differentiated action on postsynaptic activity, the same ECAR changes require a somewhat higher concentration of the reagents as compared with the concentration that produces a similar PR transformation. The higher threshold of chemical sensitivity in ECAR than in the PR depends on the characteristics of the morpho-functional organization of the cortical formations. Dissimilar reactivity of the direct cortical response and of ECAR of the parietal area to the action of chemical drugs is related to the peculiarities of intracortical origin of these potentials which are due to the dissimilar nature of their generation in response to a direct and to a peripheral stimulation.     

Physico-chemical mechanisms of transport by micropinocytosis

Blood plasma proteins adsorption on a capillar endoteliocyte membrane surface can be accompanied by the formation of protein clusters. Their superficial protein density is about 10(16) protein globules per m2. The surface density of free energy of such protein layer in a cluster is estimated according to total energy of individual protein globules hydrophobic contribution, and its value is approximately 5 mJ X m-2. It is identical to local variation quantity of the membrane free energy. An alternation of the free surface energy must lead to the appearance of chemically induced and bending moments and to the membrane distortion accompanied by the caveole forming. The blood hydrostatic pressure in capillar lumen (approximately 33 X 10(2)N X m-2) creates the membrane isotropic tension which is proportional to its value and to caveole radius. The latter according to Laplas' equation closes the caveole into the vesicula with the radius approximately 40 nm. The transport of free vesicula by cytoplasmic currents to the basal surface of an endoteliocyte results in exocytosis (which proceeds approximately 0.1 s) with a release of the vesicula surface free energy (approximately 10(-16) J). The capillar endotelium vesicular transport is the indivisible endocytosis-exocytosis process characterized by "the turnover" of the cell plasmic membrane matter without its loss.     

Study of the neurotoxic complex and its components from the venom of the Bulgarian sand viper Vipera ammodytes ammodytes: Interaction of the acidic component with cations

Addition of alkali metal ions (Li⁺, Na⁺, K⁺, Rb⁺) to the solution of isolated component A of the viper neurotoxic complex was found to pronouncedly change the protein fluorescence properties. The maximal effect takes place at the addition of potassium salts which induce the fluorescence spectral shift toward shorter wavelengths by 13.5 nm. This effect is dependent on the protein concentration and is evidence that alkali ions induce the oligomerization of component A. The oligomerization equilibrium constants are strongly dependent on both the concentration and the kind of alkali ions inducing it. The presence in the solution of Tris strongly inhibits the oligomerization. The process is temperature dependent and the oligomerization is maximal at 35–50 °C. An attempt was made to check the assumption that component A can increase the K⁺ permeability of phospholipid membranes (liposomes). The results confirmed qualitatively this assumption. Possible functional significance of these findings is discussed.     

Phosphorylation of endogenous proteins of bovine retina rod outer segments

The components of bovine rod outer segments (ROS) and water-soluble extracts of ROS were separated by SDS-electrophoresis after incubation with [gamma-32P]ATP or [gamma-32P]GTP at different experimental conditions. After that gels were autoradiographed to reveal the phosphorylated intermediates. Our results suggest, that ROS contains the following protein kinase systems: 1) water-soluble cAMP-dependent protein kinases, that uses ATP, but not GTP, and phosphorylates the water-soluble 30 000 molecular weight protein; 2) protein kinase that uses GTP (probably, ATP also) and phosphorylates the 20 000 molecular weight protein in light-adapted ROS; 3) water-soluble cyclic nucleotide- and Ca2+-independent protein kinase that uses ATP rather than GTP and phosphorylates the water-soluble 70 000 molecular weight protein. The concentrations of phosphorylated intermediates in bovine ROS are estimated.