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21.
Comparisons of the molecular evolutionary process at rbcL and ndhF in the grass family (Poaceae) 总被引:2,自引:1,他引:1
We examine rate heterogeneity among evolutionary lineages of the grass
family at two plasmid loci, ndhF and rbcL, and we introduce a method to
determine whether patterns of rate heterogeneity are correlated between
loci. We show both that rates of synonymous evolution are heterogeneous
among grass lineages and that are heterogeneity is correlated between loci
at synonymous sites. At nonsynonymous sites, the pattern of rate
heterogeneity is not correlated between loci, primarily due to an aberrant
pattern of rate heterogeneity at nonsynonymous sites of rbcL. We compare
patterns of synonymous rate heterogeneity to predictors based on the
generation time effect and the speciation rate hypotheses. Although there
is some evidence for generation time effects, neither generation time
effects nor speciation rates appear to be sufficient to explain patterns of
rate heterogeneity in the grass plastid sequences.
相似文献
22.
E. I. Solntseva 《Neurophysiology》1987,19(3):313-316
The effects of quinine on the peak amplitude and the decay of calcium currents (ICa) were investigated in nonidentified neurons isolated fromHelix pomatia. A concentration of 1×10–5–5×10–4 M quinine was found to produce a reversible dose-dependent deceleration in the decline of ICa ("lead" effect) and a reversible, slowly evolving dose-dependent reduction in ICa amplitude ("lag" effect). A reduction in amplitude down to half control level is observed at a quinine concentration of 6 ×10–5 M, while the current-voltage relationship of ICa shifts by 5–10 mV towards negative potentials. Results show that quinine successfully blocks calcium channels inHelix pomatia neurons.Institute of Brain Research, All-Union Mental Health Research Center, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 19, No. 3, pp. 413–417, May–June, 1987. 相似文献
23.
Kapai NA Bukanova JV Solntseva EI Skrebitsky VG 《Cellular and molecular neurobiology》2012,32(2):219-226
Acetylcholinesterase (AChE) inhibitor donepezil is widely used for the treatment of Alzheimer’s disease (AD). The mechanisms
of therapeutic effects of the drug are not well understood. The ability of donepezil to reverse a known pathogenic effect
of β-amyloid peptide (Abeta), namely, the impairment of hippocampal long-term potentiation (LTP), was not studied yet. The
goal of the present study was to study the influence of donepezil in 0.1–10 μM concentrations on control and Abeta-impaired
hippocampal LTP. Possible involvement of N-methyl-d-aspartate receptors (NMDARs) into mechanisms of donepezil action was also studied. LTP of population spike (PS) was studied
in the CA1 region of rat hippocampal slices. Change of LTP by donepezil treatment had a bell-shaped dose–response curve. The
drug in concentrations of 0.1 and 1 μM did not change LTP while in concentration of 0.5 μM significantly increased it, and
in concentration of 5 and 10 μM suppressed LTP partially or completely. Abeta (200 nM) markedly suppressed LTP. Addition of
0.1, 0.5 or 1 μM donepezil to Abeta solution caused a restoration of LTP. N-methyl-d-aspartate (NMDA) currents were studied in acutely isolated pyramidal neurons from CA1 region of rat hippocampus. Neither
Abeta, nor 0.5 μM donepezil were found to change NMDA currents, while 10 μM donepezil rapidly and reversibly depressed it.
Results suggest that donepezil augments control and impaired by Abeta hippocampal LTP in NMDAR-independent manner. In general,
our findings extend the understanding of mechanisms of therapeutic action of donepezil, especially at an early stage of AD,
and maybe taken into account while considering the possibility of donepezil overdose. 相似文献
24.
Solntseva SV Nikitin VP 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2010,96(12):1212-1222
We have previously found two stages of amnesia evoked by disruption of memory reconsolidation with MK-801 (NMDA glutamate receptors antagonists) application in food aversion conditioned snails. Repeated conditioning restored the food aversion at early stage of amnesia development (<10 days), whereas repeated conditioning 10 days after MK-801 application did not restore the food aversion. In present work, amnesia was induced with MK-801/reminding 24 hours after food aversion conditioning, and antiamnestic effects of NMDA receptor glycine site agonist d-cycloserine were studied at early (3rd day) or late (12th day) stages of amnesia development. D-cycloserine injection and reminding restored memory only 3 days after amnesia induction whereas d-cycloserine injection without reminding was ineffective. D-cycloserine injection and reminding as well as repeated learning 12 days after amnesia induction were also ineffective in memory restoration. Thus, for the first time, it is revealed that NMDA receptor agonist d-cycloserine influences the memory restoration processes only at early but not the later stages of amnesia development. 相似文献
25.
The K(+)-channels of the surface membrane play a crucial role in the generation of electrical activity of a neuron. There is a large diversity of the K(+)-channels that depends on a great number (over 200) of genes encoding channels proteins. An evolutionary conservation of channel's proteins is determined. The K(+)-channels were found to have a great importance in the memory processes. It was shown on different model systems that K(+)-current of the surface membrane decreases during the learning. The antagonists of K(+)-channels were found to improve the learning and memory. It was revealed in electrophysiological experiments that K(+)-channels antagonists can either themselves induce a long-term synaptic potentiation or intensify the synaptic potentiation induced by a tetanization. The disfunction of K(+)-channels is believed to be an important link in the mechanisms of memory disturbances. In animal mutants with K(+)-channels disfunction, learning and memory are deficient. In behavioral experiments, the use of K(+)-channels openers make the learning worse. Amnesia caused by cerebral ischemia is explained by strong activity of K(+)-channels which not only inhibits neuronal excitement but also causes neurodegeneration. The question on the K(+)-channels involvement into pathophysiology of Alzheimer's disease is discussed. Neurotoxic peptide beta-amyloid, which is supposed to be involved into mechanisms of Alzheimer's disease, modulates K(+)-channels function. The effect of beta-amyloid depends on the subtype of K(+)-channels: A-channels are inhibited, and KDR-channels, on the contrary, become stronger. The effect of the cognitive enhancers (vinpocetine, piracetam, tacrine, linopirdine) on K(+)-current also depends on the subtype of K(+)-channels. Slow-inactivating K(+)-currents (IDR, IK(Ca), IM) are inhibited in the presence of these drugs, while fast-in-activating K(+)-current (A-current) remains unchanged or even increases. 相似文献
26.
E. I. Solntseva 《Neurophysiology》1993,25(6):354-358
A low-threshold outward current was studied in the neurons ofHelix pomatia at –70 to –30 mV using a two-electrode voltage clamp technique. In addition to the well-known A current (I
A), a slower outward current calledI
As (slow) was revealed. Activation and inactivation times ofI
As at –40 mV ranged from 90 to 120 msec and from 3 to 5 sec, respectively. The current recovered within 2 to 5 sec after inactivation at –120 mV. Analysis of changes in the reversal potential ofI
As caused by an increase in external potassium concentration suggests a potassium origin forI
As. The curves ofI
As stationary activation and inactivation fit the Boltzmann equation. Deriving from an activation curve, the activation potential for a half-maximum current,, is –40 mV, and the slope factor,k, is –9.8 mV, while those values for the inactivation curve are –84 mV (a half-maximum inactivation) and 7.5 mV.I
As is blocked by 4-aminopyridine (1–30 µM), tetraethylammonium (1 mM), and Ba2+ (1 mM), but is resistant to Cs+ (1 mM). PeakI
As is not affected either by substitution of external Ca2+ for Mg2+ or by application of Cd2+ (0.5–1.0 mM). The results suggest that activation ofI
As does not require Ca2+ entry into the cell.Neirofiziologiya/Neurophysiology, Vol. 25, No. 6, pp. 427–432, November–December, 1993. 相似文献
27.
The sites of specific binding of 3H-L-dihydroalprenolol (3H-DHA) were identified on the surface of ascites sarcoma 37 cells, using competitive displacement and binding of the beta-adrenergic antagonists, 3H-DHA and L-propranolol. These binding sites possessed the properties of beta-adrenergic receptors coupled with adenylate cyclase. Analysis of 3H-DHA binding by the Scatchard method revealed the presence of beta-adrenergic receptors of two types, i. e., with a high (Kd = 0.9-1.0 nM) and low (Kd = 15-20 nM) affinity for 3H-DHA. The number of high affinity receptors was (5.0-7.5) X 10(3); that of low affinity receptors was (20-30) X 10(3) on a per cell basis. Sarcolysine at concentrations of 1-10 microM displaced receptor-bound 3H-DHA, competed with the ligand for the common binding sites and caused, similar to isoproterenol, a short-term elevation of the intracellular cAMP content. Sarcolysine within the same concentration range (2.5-25 microM) caused non-competitive inhibition of the cAMP phosphodiesterase (PDE2) activity of plasma membranes isolated from ascites sarcoma 37 cells. The data obtained point to the functional coupling between beta-adrenergic receptors, adenylate cyclase and membraneous PDE2 of tumour cells as well as to its possible role in the antitumour effect of sarcolysine. 相似文献
28.
Solntseva SV Nikitin VP 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2008,94(8):860-870
Effects of cycloheximide, protein synthesis inhibitor as well as serotonin receptor antagonist and NMDA receptor antagonist, on food aversion conditioning consolidation were studied in snail Helix lucorum. Food aversion conditioning was absent in snails after application of cycloheximide. Repeated training produced no food aversion conditioning for the same type of food in these snails without cycloheximide application. Food aversion conditioning was absent in snails after metiotepin, nonselective serotonin receptors antagonist, or after MK-801, NMDA glutamate receptors antagonist, applications. At the same time, repeated training produced facilitated food aversion conditioning for the same type of food in these snails. Our experiments were the first which showed that effect on different molecular mechanisms evoked reversible or irreversible disruption of long-term memory consolidation during the same learning. It was suggested that suppression of retrieval produced reversible effect whereas disruption of memory storage initiated irreversible effect on long-term memory consolidation. 相似文献
29.
E. I. Solntseva 《Neurophysiology》1991,23(5):373-377
A two-microelectrode voltage-clamp method was used to measure a high-threshold calcium current (ICa) on isolated snail neurons. Tolbutamide (1–5 mmole/liter) and H-8 (1–30 µmole/liter), inhibitors of kinase A, caused a decrease in the peak amplitude and accelerated ICa decay during a depolarizing stimulus. The half-life of the "slow" time constant of ICa decay decreased in the presence of tolbutamide, and was two to three times stronger than the half-life of the "fast" time constant. ICa inactivation curves plotted in a double-stimulus experiment have shown that after tolbutamide application, ICa inactivation elicited by the application of high-amplitude depolarizing pre-stimuli preferentially rises (Vc=+30 to +70 mV). The results suggest that dephosphorylation of Ca2+ channels enhances a potential-dependent component of the inactivation process.Scientific-Research Institute of the Brain, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 23, No. 5, pp. 515–519, September–October, 1991. 相似文献
30.
But Sergey Y. Solntseva Natalia P. Egorova Svetlana V. Mustakhimov Ildar I. Khmelenina Valentina N. Reshetnikov Alexander Trotsenko Yuri A. 《Extremophiles : life under extreme conditions》2018,22(3):433-445
Extremophiles - Four enzymes involved in sucrose metabolism: sucrose phosphate synthase (Sps), sucrose phosphate phosphatase (Spp), sucrose synthase (Sus) and fructokinase (FruK), were obtained as... 相似文献