Regulation of the mouse aggressive behavior (pharmacologic analysis of the GABAergic mechanism)

Ethological procedures were used to study the effects of GABA-positive drugs on aggression in male albino mice kept in isolation (opponent test). The results revealed several variants of antiaggressive effects of the tested GAB Aergic drugs: 1) antiaggressive, re-socializing of GABAA agonists muscimol (0.125 and 0.5 mg/kg) and THIP (2.0 mg/kg), and GABAB agonist baclofen (2.5-10 mg/kg); 2) antiaggressive, sedative of GABAB agonists baclofen (12.5 mg/kg), phenibut (50-100 mg/kg), and inhibitor of GABA transamininase sodium valproate (100 mg/kg); 3) antiaggressive, anxiogenic for muscimol (1 mg/kg), THIP (5 mg/kg), and sodium valproate (25-50 mg/kg).     

Interaction of the N-terminus of chicken skeletal essential light chain 1 with F-actin

Skeletal myosin has two isoforms of the essential light chain (ELC), called LC1 and LC3, which differ only in their N-terminal amino acid sequence. The LC1 has 41 additional residues containing seven pairs of Ala-Pro, which form an elongated structure, and two pairs of lysines located near the N-terminus. When myosin subfragment-1 (S1) binds to actin, these lysines may interact with the C-terminus of actin and be responsible for the isoform specific properties of myosin. Here we employ cross-linking to identify the LC1 residues that are in contact with actin. S1 was reconstituted with various LC1 mutants and reacted with the zero-length cross-linker 1-ethyl-3-[3-dimethyl-aminopropyl]-carbodiimide (EDC). Cross-linking occurred only when actin was in molar excess over S1. Wild-type LC1 could be cross-linked through the terminal alpha-NH2 group, as well as via the two pairs of lysines. In a mutant ELC, where the lysines were deleted but two arginines were introduced near the N-terminus, the light chain could still be cross-linked via the terminal alpha-NH2 group. When the charge was reduced in the N-terminal region while retaining the Ala-Pro rich region, the mutant could not be cross-linked. These results suggest that as long as the N-terminus contains charged residues and an Ala-Pro rich extension, the binding between LC1 and actin can occur.     

The Na<Superscript>+</Superscript>-translocating ATPase in the plasma membrane of the marine microalga<Emphasis Type="Italic"> Tetraselmis viridis</Emphasis> catalyzes Na<Superscript>+</Superscript>/H<Superscript>+</Superscript> exchange

Our previous investigations have established that Na⁺ translocation across the Tetraselmis viridis plasma membrane (PM) mediated by the primary ATP-driven Na⁺-pump, Na⁺-ATPase, is accompanied by H⁺ counter-transport [Y.V. Balnokin et al. (1999) FEBS Lett 462:402–406]. The hypothesis that the Na⁺-ATPase of T. viridis operates as an Na⁺/H⁺ exchanger is tested in the present work. The study of Na⁺ and H⁺ transport in PM vesicles isolated from T. viridis demonstrated that the membrane-permeant anion NO₃^– caused (i) an increase in ATP-driven Na⁺ uptake by the vesicles, (ii) an increase in (Na⁺+ATP)-dependent vesicle lumen alkalization resulting from H⁺ efflux out of the vesicles and (iii) dissipation of electrical potential, , generated across the vesicle membrane by the Na⁺-ATPase. The (Na⁺+ATP)-dependent lumen alkalization was not significantly affected by valinomycin, addition of which in the presence of K⁺ abolished at the vesicle membrane. The fact that the Na⁺-ATPase-mediated alkalization of the vesicle lumen is sustained in the absence of the transmembrane is consistent with a primary role of the Na⁺-ATPase in driving H⁺ outside the vesicles. The findings allowed us to conclude that the Na⁺-ATPase of T. viridis directly performs an exchange of Na⁺ for H⁺. Since the Na⁺-ATPase generates electric potential across the vesicle membrane, the transport stoichiometry is mNa⁺/nH⁺, where m>n.Abbreviations BTP Bis-Tris-Propane, 1,3-bis[tris(hydroxymethyl)methylamino]-propane - CCCP Carbonyl cyanide m-chlorophenylhydrazone - DTT Dithiothreitol - NCDC 2-Nitro-4-carboxyphenyl N,N-diphenylcarbamate - PMSF Phenylmethylsulfonyl fluoride - PM Plasma membrane     

Testaceans (Protozoa: Testacea) in Quaternary Permafrost Sediments of Bykovsky Peninsula, Arctic Yakutia

The results of the first protozoological study in terms of paleoecology of long-term sediments and buried soils formed in the cryolite zone of northeastern Siberia are discussed. The data on testaceans (Protozoa: Testacea) inhabiting various sites of Bykovsky Peninsula, Laptev Sea coast near estuary of Lena, within the last 53000 years (Late Pleistocene and Holocene) are presented.     

Comparative characterization of the two primary pumps, H+-ATPase and Na+-ATPase, in the plasma membrane of the marine alga Tetraselmis viridis

The transport characteristics of the plasma membrane H⁺‐ATPase (PMHA) and Na⁺‐ATPase (PMNA) from marine unicellular green alga Tetraselmis viridis Rouch. were studied using sealed plasma membrane vesicles isolated from this species. The activities of the ATPases were investigated by monitoring the ATP‐dependent pH changes in the vesicle lumen. PMHA operation led to acidification of the vesicle lumen, whereas Na⁺ translocation into plasma membrane vesicles catalysed by PMNA was accompanied by H⁺ efflux, namely the alkalization of the vesicle lumen (Balnokin et al., FEBS Lett 462: 402–406, 1999). The intravesicular acidification and alkalization were detected with the ΔpH probe acridine orange and the pH probe pyranine, respectively. PMHA and PMNA were found to operate in distinct pH regions, maximal activity of PMHA being observed at pH 6.5 and that of PMNA at pH 7.8. Kinetic studies revealed that the ATPases have similar affinities to their primary substrate, MgATP complex (an apparent K_m = 34 ± 6.2 µM for PMHA and 73 ± 8.7 µM for PMNA). At the same time, the ATPases were differently affected by free Mg²⁺ and ATP. Free Mg²⁺ appeared to be a mixed‐type inhibitor for PMNA (K_i′ = 210 µM) but it did not suppress PMHA. Conversely, free ATP markedly suppressed PMHA being a mixed‐type inhibitor (K_i′ = 330 µM), but PMNA was affected by free ATP only slightly. Furthermore, the ATPases substantially differed in their sensitivities to the inhibitors of membrane ATPases, such as orthovanadate, N‐ethylmaleimide and N,N′‐dicyclohexylcarbodiimide. The differences found in the properties of the PMHA and PMNA are discussed in terms of regulation of their activities and their capacity to be involved in cytosolic ion homeostasis in T. viridis cells.     

Neuronal responses mediated by activation of the non-NMDA receptors: Potentiation by nootropes

Experiments on superfused slices of rat hippocampus showed that the nootropic drugs pyracetam, ethymizol, ambocarb, and nooglutil increase the amplitude of populational EPSP (pEPSP) of neurons of the dentate gyrus evoked by electrical stimulation of the perforant pathway (PP). Nootropes exert no effect on the process of presynaptic glutamate liberation from the PP axons, but increase the chemosensitivity of the postsynaptic AMPA/kainate receptors mediating EPSP generation in the dentate gyrus neurons. Inhibitors of protein kinase (A-buthamide) and guanylatecyclase (methylene blue) do not modify the effects of nootropes. The nootrope-induced potentiation of pEPSP does not develop against the background of the application of calmodulin inhibitor W-7. In the presence of protein kinase inhibitor C, polymixin B, nootropes reversibly depress pEPSP in the dentate gyrus neurons. Blocking of the NMDA receptor ionic channels by ketamine and of the voltage-dependent T-type calcium channels by Ni²⁺ does not significantly modify the effects of nootropic drugs. A blocker of Ca²⁺-ATPase of the Ca²⁺ stores sodium orthovanadate, potentiates the effects of nootropes. Dantrolene, which disrupts Ca²⁺ liberation from the non-mitochondrical depots, blocks the effects of nootropes and diminishes pEPSP depression evoked by nootropes in the presence of polymixin B. On the basis of presented data, it is supposed that nootropic drugs assist Ca²⁺ liberation from the neuronal depots and activate calmodulin-dependent protein kinase and protein kinase C. Protein kinases phosphorylate the intracellular domains of the AMPA/kainate receptors, and this process results in an increase in their sensitivity to excitatory amino acids.Neirofiziologiya/Neurophysiology, Vol. 26, No. 5, pp. 365–372, September–October, 1994.     

Calcium is involved in regulation of the synthesis of HSPs in suspension-cultured sugar beet cells under hyperthermia

Exposure of plants to elevated temperatures induces a complex set of changes that enable plants to adapt following heat stress. In order to test the effect of Ca²⁺ on heat shock-induced changes in cell protein synthesis the incorporation of [ 35 S]methionine into protein was studied in cultured sugar beet ( Beta vulgaris L.) cells incubated in media containing different calcium concentrations. Heat shock inhibited the synthesis of non-heat shock proteins (non-HSPs) and promoted the synthesis of a set of HSPs, typical of plants. The synthesis of non-HSPs was greatly inhibited by external Ca²⁺ removal by treatment of the cells with ethylene glycol-bis( β -aminoethylether)- N,N,N',N'- tetraacetic acid. In contrast, extracellular Ca²⁺ appeared not to be strictly required for the de novo production of HSPs, but this cation exerted different effects on the synthesis of individual HSPs. Cell injury increased if the cells were exposed simultaneously to high temperature and Ca²⁺-deficient medium. Recovery of HSP synthesis and reduced cell injury were observed after addition of exogenous calcium to Ca²⁺-depleted cells. These findings are consistent with a Ca²⁺ requirement for the survival of the cells under heat shock, and likely for the development of cell thermotolerance.     

The identification of tryptophan residues responsible for ATP-induced increase in intrinsic fluorescence of myosin subfragment 1

ATP binding to myosin subfragment 1 (S1) induces an increase in tryptophan fluorescence. Chymotryptic rabbit skeletal S1 has 5 tryptophan residues (Trp113, 131, 440, 510 and 595), and therefore the identification of tryptophan residues perturbed by ATP is quite complex. To solve this problem we resolved the complex fluorescence spectra into log-normal and decay-associated components, and carried out the structural analysis of the microenvironment of each tryptophan in S1. The decomposition of fluorescence spectra of S1 and S1-ATP complex revealed 3 components with maxima at ca. 318, 331 and 339-342 nm. The comparison of structural parameters of microenvironment of 5 tryptophan residues with the same parameters of single-tryptophan-containing proteins with well identified fluorescence properties applying statistical method of cluster analysis, enabled us to assign Trp595 to 318 nm, Trp440 to 331 nm, and Trp 13, 131 and 510 to 342 nm spectral components. ATP induced an almost equal increase in the intensities of the intermediate (331 nm) and long-wavelength (342 nm) components, and a small decrease in the short component (318 nm). The increase in the intermediate component fluorescence most likely results from an immobilization of some quenching groups (Met437, Met441 and/or Arg444) in the environment of Trp440. The increase in the intensity and a blue shift of the long component might be associated with conformational changes in the vicinity of Trp510. However, these conclusions can not be extended directly to the other types of myosins due to the diversity in the tryptophan content and their microenvironments.     

Displaying behaviour and mating system in the Siberian Spruce Grouse (Falcipennis falcipennis Hartlaub 1855)

Summary The Siberian Spruce Grouse (Falcipennis falcipennis) is a species endemic to far-eastern Russia and a close relative toF. canadensis andF. franklinii of North-America. Prior to this study, little was known about the display behaviour, social organisation and seasonal movements of this grouse. We investigated these topics in 1990–1997, in 2 areas, 100 km N and 200 km NW of Komsomolsk/Amur. We caught, measured and marked 80 individuals. We determined the age of cocks by the size of combs and the length of neck feathers. Spatial organisation of the local population was studied by equipping 60 birds with transmitters and following them all-year-round.During the reproductive period males and females were territorial. Winter flocks (2–6 birds) break up by late March or early April, and spring flocks break up 1 month later. Cocks were present at the display ground from April 1 to May 25. Females visited the display grounds from April 25 to May 10. Eggs were laid between May 7 and May 20. The main display performances of cocks (upright posture and tail flicks, walks with tail swish, flutter jumps, flutter flights, drumming flights), courtship and agonistic behaviour were analysed from photographs and video recordings. Three-year-old cocks carried out most of the copulations. During the high season of display, we recorded activity (morning and evening displays, moving versus roosting) during continuous observations and counted flutter jumps, flutter flights and drumming flights.Parts of the displays of the Siberian spruce grouse are more diversified than those of the North-American species. The communication system is perfectly adapted to the dense habitat of the mountain taiga. Different acoustic signals for communication at very short, medium and longer distances seem to have evolved under specific predation pressure. The territorial system is very flexible, ranging from individual display grounds to an arena-like structure. The mating system is polygyny.

---

Balzverhalten und Paarungssystem des Sichelhuhns (Falcipennis falcipennis Hartlaub 1855)

Zusammenfassung Das Sichelhuhn (Falcipennis falcipennis) als endemisches Raufußhuhn des Fernen Ostens Russlands ist eng verwandt mit den nordamerikanischen FichtenhühnernF. canadensis undF. franklinii. Von 1990–1997 wurden Ökologie und Verhalten dieser Art in zwei Gebieten (100 km N und 200 km NW von Komsomolsk am Amur) studiert. 80 Vögel wurden gefangen, vermessen und markiert. Zwei Maße (Größe der Überaugenwülste und Halsfederlänge) gestatten eine Altersbestimmung der Hähne. 60 besenderte Vögel lieferten rund um das Jahr Daten zu Raum- und Habitatnutzung, Reproduktion und Mortalität. Individuelle Markierung und Ortung zu beliebigen Zeiten erleichterten auch die Verhaltensstudien. In der Reproduktionsperiode besaßen sowohl Hähne als auch Hennen Reviere. Winterflüge aus 2–6 Vögeln lösten sich Ende März/Anfang April auf; die Frühjahresgruppen einen Monat später. Die Hähne waren im Mittel zwischen 1. April und 25. Mai an den Balzplätzen anzutreffen, die Hennen erschienen dort zwischen 25. April und 10. Mai. Zwischen 7. und 20. Mai erfolgte die Eiablage. Die wichtigsten Elemente des Territorialverhaltens (Aufrechthaltung mit Schwanzspreizen, Imponierläufe mit Schwanzfederzischen, Flattersprünge, Flatterflüge und Trommelflüge), Revierverteidigung und Werbung werden nach Foto- und Videoaufzeichnungen beschrieben. Dreijährige Hähne vollzogen die meisten Paarungen. Zwischen 1. und 9. Mai, wenn Werbe- und Paarungsverhalten kulminieren, wurden durch Ganztagsbeobachtungen Morgen- und Abendaktivität, Ortsveränderungen und Ruhephasen quantitativ erfasst, ebenso der tägliche Anteil von Flattersprüngen, Flatter-und Trommelflügen. Im Vergleich zu den nordamerikanischen Geschwisterarten sind Teile des Verhaltensrepertoires des Sichelhuhns zur Balzzeit stärker differenziert. Das Kommunikationssystem ist an dichte Habitate der borealen Bergtaiga angepasst: Verschiedene akustische Signale, die auf sehr kurze, mittlere and längere Distanzen wirken, sind offenbar in Anpassung an den spezifischen Feinddruck entstanden. Das Reviersystem erscheint flexibel: Die Spanne reicht von solitär agierenden Hähnen bis zu Arena — ähnlichen Balzplätzen. Das Paarungssystem ist Polygynie.

     

Src and Pyk2 mediate G-protein-coupled receptor activation of epidermal growth factor receptor (EGFR) but are not required for coupling to the mitogen-activated protein (MAP) kinase signaling cascade

The epidermal growth factor receptor (EGFR) and the non-receptor protein tyrosine kinases Src and Pyk2 have been implicated in linking a variety of G-protein-coupled receptors (GPCR) to the mitogen-activated protein (MAP) kinase signaling cascade. In this report we apply a genetic strategy using cells isolated from Src-, Pyk2-, or EGFR-deficient mice to explore the roles played by these protein tyrosine kinases in GPCR-induced activation of EGFR, Pyk2, and MAP kinase. We show that Src kinases are critical for activation of Pyk2 in response to GPCR-stimulation and that Pyk2 and Src are essential for GPCR-induced tyrosine phosphorylation of EGFR. By contrast, Pyk2, Src, and EGFR are dispensable for GPCR-induced activation of MAP kinase. Moreover, GPCR-induced MAP kinase activation is normal in fibroblasts deficient in both Src and Pyk2 (Src-/-Pyk2-/- cells) as well as in fibroblasts deficient in all three Src kinases expressed in these cells (Src-/-Yes-/-Fyn-/- cells). Finally, experiments are presented demonstrating that, upon stimulation of GPCR, activated Pyk2 forms a complex with Src, which in turn phosphorylates EGFR directly. These experiments reveal a role for Src kinases in Pyk2 activation and a role for Pyk2 and Src in tyrosine phosphorylation of EGFR following GPCR stimulation. In addition, EGFR, Src family kinases, and Pyk2 are not required for linking GPCRs with the MAP kinase signaling cascade.