Number of results to display per page
Search Results
68152. The influence of y-radiation on the kinetic of changes in violaxanthin content and on the xanthophyll cycle
- Creator:
- Saakov, V. S.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- In Phaseolus and Robinia leaves, direct light reaction (de-epoxidatíon of violaxanthín) was inhibited during 7-9 h as an aftereffect of y-radiation (167 mGy s'*). Complete suppression of the light reaction by the de-epoxidation was reached after 12-14 h. The suppression of xanthophyll de-epoxidation reflects the inhibitíon of photosynthetic electron transport chain and may be ušed for testing deleterious efifects on plants.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68153. The influence of yellow lupin intercropped with spring triticale on predatory carabid beetles (Coleoptera: Carabidae)
- Creator:
- Hurej, Michal and Twaardowski, Jacek P.
- Type:
- article, model:article, and TEXT
- Subject:
- Carabid beetles, Pseudoophonus rufipes, abundance, activity, intercropping, yellow lupin, spring triticale, and shelter
- Language:
- English
- Description:
- Intercropping may have a positive effect on the abundance and activity of carabid beetles and therefore their response to intercropping yellow lupin with spring triticale was studied for a period of three years (2001-2003). Carabids were most numerous in yellow lupin monoculture and in the intercrop with the highest proportion of lupin. Important differences between the experimental treatments were found, but they were mostly non-significant because of the great variation between samples. It is supposed that the positive effect of lupin on carabid beetles was due to the shelter it provides. During the three-year study 59 species of carabid beetles were recorded. The most abundant species in each treatment was Pseudoophonus rufipes. Irrespective of the experimental treatment, this species was caught in the greatest numbers towards the end of each growing season. This was probably because of the greater soil coverage provided by the larger lupin plants at the end of the season.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68154. The inhibition of angiotensin converting enzyme attenuates the effects of chronic hypoxia on pulmonary blood vessels in the rat
- Creator:
- Herget, J., Pelouch, V., Kolář, F., and Ošťádal, B.
- Type:
- article, model:article, and TEXT
- Subject:
- pulmonary hypertension, collagen, chronic hypoxia, angiotensin II, and angiotensin converting enzyme
- Language:
- English
- Description:
- The effect of chronic administration of angiotensin converting enzyme inhibitor on the development of hypoxic pulmonary hypertension was studied in rats. Male Wistar rats were exposed for 3 weeks to isobaric hypoxia (10 % O2) and treated with 10 mg/kg b.w. of Ramipril daily. The haemodynamic properties of the pulmonary vasculature were then measured in isolated blood-perfused lung preparation. Ramipril administration during the sojourn in hypoxia resulted in lower baseline perfusion pressure and lower slope of perfusion pressure-flow relationship compared to non-treated hypoxic rats. Partitioning of the distribution of pulmonary vascular resistance across the vascular bed by the occlusion technique showed that it was mainly due to a decrease of arterial and venous vascular resistances to blood flow. It is suggested that Ramipril attenuates the process of morphological reconstruction of pulmonary vasculature by chronic hypoxia rather than the level of vascular smooth muscle tone.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68155. The Inhibitory Effects of Dantrolene on Action Potential-Induced Calcium Transients in Cultured Rat Dorsal Root Ganglion Neurons
- Creator:
- Ahmet Ayar and Kelestimur, H.
- Format:
- print, bez média, and svazek
- Type:
- article, studie, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Dantrolene, CICR, Action potential after-potentials, Cultured sensory neurons, Patch clamp, 14, and 612
- Language:
- English
- Description:
- We investigated the actions of dantrolene Ca2+-induced on Ca2+-release (CICR) evoked by action potentials in cultured rat sensory neurons. The effect of dantrolene on action potential after-depolarization and voltage-activated calcium currents was studied in cultured neonatal rat dorsal root ganglion cells (DRG) using the whole-cell patch-clamp technique. Depolarizing current injection evoked action potentials and depolarizing after-potentials, which are activated as a result of CICR following a single action potential in some cells. The type of after-potentials was determined by inducing action potentials from the resting membrane potential. Extracellular application of dantrolene (10 mM) abolished after-depolarizations without affecting action potential properties. Furthermore, dantrolene significantly reduced repetitive action potentials after depolarizing current injection into these neurons, but had no significant effect on the steady-state current voltage relationship of calcium currents in these neurons. We conclude that dantrolene inhibits the induction of action potential after depolarizations by inhibiting CICR in cultured rat sensory neurons., A. Ayar, H. Kelestimur., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68156. The initial phase of cosmological evolution and the formation of structure in the universe
- Creator:
- Gottlöber, S., Haubold, H. J., Mücket, J. P., and Müller, V.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- cosmology and structure in the universe
- Language:
- Czech
- Description:
- A singularity-free inflationary cosmological model driven by a coherent scalar field and/or R^2 terms in the gravitational Lagrangian is presented. The different mechanisms are compared and their observational restrictions are discussed. The dark matter problem and the mode coupling effect connecting the formation of very large structures and population III objects find a natural place in our model.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68157. The integrability of a field of endomorphisms
- Creator:
- Thompson, Gerard
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- integrability, endomorphism, and quotient space
- Language:
- English
- Description:
- A Theorem is proved that gives intrinsic necessary and sufficient conditions for the integrability of a zero-deformable field of endomorphisms. The Theorem is proved by reducing to a special case in which the endomorphism field is nilpotent. Many arguments used in the derivation of similar results are simplified, principally by means of using quotient rather than subspace constructions.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68158. The integral points on elliptic curves $y^2=x^3+(36n^2 -9)x-2(36n^2-5)$
- Creator:
- Yang, Hai and Fu, Ruiqin
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- elliptic curve, integral point; quadratic, and diophantine equation
- Language:
- English
- Description:
- Let $n$ be a positive odd integer. In this paper, combining some properties of quadratic and quartic diophantine equations with elementary analysis, we prove that if $n>1$ and both $6n^2-1$ and $12n^2+1$ are odd primes, then the general elliptic curve $y^2=x^3+(36n^2 -9)x-2(36n^2-5)$ has only the integral point $(x, y)=(2, 0)$. By this result we can get that the above elliptic curve has only the trivial integral point for $n=3, 13, 17$ etc. Thus it can be seen that the elliptic curve $y^2=x^3+27x-62$ really is an unusual elliptic curve which has large integral points.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68159. The interacting effect of urea and fenoxaprop-P-ethyl on photosynthesis and chlorophyll fluorescence in Perilla frutescens
- Creator:
- Zhang, J. H., Guo, S. J., Guo, P. Y., and Wang, X.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, herbicidy, photosynthesis, herbicides, Labiatae, photosynhetic parameters, Perilla frutescens, 2, and 581
- Language:
- Multiple languages
- Description:
- We studied the effect of herbicide and nitrogen supply on photosynthesis in Perilla frutescens L. Britt. Plants were exposed to combined treatment of urea and herbicide, fenoxaprop-P-ethyl (FPE), in various concentrations. FPE reduced significantly chlorophyll (Chl) content, photosynthetic rate, and stomatal conductance, but increased significantly intercellular CO2 concentration; thus, FPE inhibited significantly the photosynthetic capacity. In addition, FPE also decreased significantly the PSII photochemical efficiency, effective quantum yield of photochemical energy conversion in PSII, PSII potential activity, and photochemical quenching of variable Chl fluorescence. It also decreased nonphotochemical quenching. It indicated that FPE impaired PSII and blocked the electron transport in light reaction. The urea treatment at moderate concentration (1-4 g L-1) could antagonize the negative effect of FPE, while the high urea concentration (8 g L-1) aggravated this effect. The treatment with urea (4 g L-1) and then with FPE (1.33 mL L-1) enhanced Chl content index, photosynthetic rate, and stomatal conductance by 12.5, 36.1, and 28.5% compared to FPE treatment alone. Thus, we suggested to treat plants first with urea (4 g L-1) and then by FPE (1.33 mL L-1) as the best and the safest method to balance the fertilization and weeding., J. H. Zhang, S. J. Guo, P. Y. Guo, X. Wang., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68160. The interaction of calcium entry and calcium sensitization in the control of vascular tone and blood pressure of normotensive and hypertensive rats
- Creator:
- Josef Zicha, Behuliak, M., Mária Pintérová, Bencze, M., Jaroslav Kuneš, and Ivana Vaněčková
- Format:
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, vápník, cévy, krevní tlak, calcium, vessels, blood pressure, calcium sensitization, RhoA/Rho kinase, fasudil, Ca2+ entry, nifedipine, BAY K8644, 14, and 612
- Language:
- English
- Description:
- ncreased systemic vascular resistance is responsible for blood pressure (BP) elevation in most forms of human or experimental hypertension. The enhanced contractility of structurally remodeled resistance arterioles is mediated by enhanced calcium entry (through L type voltagedependent calcium channels - L-VDCC) and/or augmented calcium sensitization (mediated by RhoA/Rho kinase pathway). It is rather difficult to evaluate separately the role of these two pathways in BP control because BP response to the blockade of either pathway is always dependent on the concomitant activity of the complementary pathway. Moreover, vasoconstrictor systems enhance the activity of both pathways, while vasodilators attenuate them. The basal fasudil-sensitive calcium sensitization determined in rats deprived of endogenous renin-angiotensi n system (RAS) and sympathetic nervous system (SNS) in wh ich calcium entry was dose- dependently increased by L-VDCC opener BAY K8644, is smaller in spontaneously hypertensive rats (SHR) than in normotensive Wistar-Kyoto (WKY) rats. In co ntrast, if endogenous RAS and SNS were present in intact rats, fasudil caused a greater BP fall in SHR than WKY rats. Our in vivo experiments indicated that the endogenous pressor systems (RAS and SNS) augment calcium sensitization mediated by RhoA/Rho kinase pathway, whereas the endogenous vasodilator systems (such as nitric oxide) attenuate this pathway. However, the modulation of calcium entry and calcium sensitization by nitric oxide is strain-dependent because NO deficiency significan tly augments low calcium entry in WKY and low calcium sensitization in SHR. Further in vivo and in vitro experiments should clarify the interrelationships between endogenous vasoactive systems an d the contribution of calcium entry and/or calcium sensitization to BP maintenance in various forms of experimental hypertension., J. Zicha ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public