Field-grown plants of spring barley (Hordeum vulgare L. cv. Akcent) in the growth phase 30 DC (beginning of stem extension) were exposed to a one-shot application of a commercial product containing cyanazine (Bladex 50 SC) in two doses, C30 and C60 (30 and 60 mg m-2). The reaction of the plant photosynthetic system was followed non-destructively using chlorophyll fluorescence induction (the O-J-I-P transient) within three weeks after the application in the fifth developed leaf and three further gradually appearing leaves. An immediate response of plants to the application of cyanazine and a regeneration of plants from cyanazine action were detected. The biological (plant dry mass) and crop yield production (the number and mass of grains in a spike) were analyzed in time of full ripeness. The crop yield was lowered by the herbicide effect to the same level for the two doses used. and M. Matoušková, J. Nauš, M. Flašarová.
Iron is an essential limiting factor for primary production in many marine systems. The present study investigated differential regulation of protein expression in marine phytoplankton Prymnesium parvum under low Fe concentration. The phytoplankton was grown in f/2 culture medium in artificial seawater with low (0.0025 μM) and high (0.05 μM) Fe concentrations. Two-dimensional differential gel electrophoresis and matrix-assisted laser desorption-ionization-time of flight-mass spectrometer analysis were performed for protein identification and characterization. The growth of the alga declined substantially under the low Fe compared to the high Fe concentration. Under low Fe conditions, P. parvum upregulated 10 proteins including chloroplastic ATP synthase subunit b, D2 protein of PSII, D1 protein of PSII reaction centre, and light harvesting complex II protein, most of which are associated with photosynthetic activities in PSII. The results suggest that the marine alga P. parvum altered the biosynthesis of several photosynthetic proteins in order to cope with low Fe conditions., M. M. Rahman, M. A. Rahman, T. Maki, T. Nishiuchi, T. Asano, H. Hasegawa., and Obsahuje bibliografii
A modified exponential model was used to describe light-response curves of Nicotiana tabacum L. The accuracies of an exponential model, a nonrectangular hyperbola model, a rectangular hyperbola model, a modified rectangular hyperbola model and the modified exponential model were evaluated by Mean square error (MSE) and Mean absolute error (MAE). The tests MSE and MAE of the modified exponential model were the lowest among the five models. The light saturation point (LSP) obtained by the exponential model, the nonrectangular hyperbola model and the rectangular hyperbola model were much lower than the measured values, and the maximum net photosynthetic rates (Pmax) calculated from these models, were greater than the measured values. Pmax at LSP of 1,077 μmol m-2 s-1 calculated by the modified exponential model was 12.34 μmol(CO2) m-2 s-1, which was more accurate than the values obtained from the modified rectangular hyperbola model. The results show that the modified exponential model is superior to other models for describing light-response curves. and Z. Y. Chen ... [et al.].
In this paper, we present a novel quantitative description of intracellular and t-tubular Ca2+ dynamics in a model of rat cardiac ventricular myocyte. In order to simulate recently published data, the model incorporates t-tubular and peripheral dyads and intracellular subspaces, segmentation of the t-tubular luminal volume, reformulation of the inactivation properties of t-tubular land peripheral L-type calcium current (ICa) and a description of exogenous Ca2q+ buffer function in the intracellular space. The model is used to explore activity-induced changes of ion concentration in the intracellular and t-tubular spaces and their role in excitation - contraction coupling in ventricular myocytes. and Obsahuje Appendix se seznamy literatury, užitých zkratek a symbolů
The general author‘s mesomechanical model with tensorial internal variables is applied to creep of steel 0,5Cr0,5Mo0,3V under different loading levels. It is shown that the creep process can be described by the mesomechanical model in its whole course up to rupture. However, the model parameters can be influenced at the very beginning by the application of the applied load if it is high enough to cause changes in the internal structure. This problem is specific for creep at high temperatures and significant differences in the loading levels (contrary to the small-strain plasticity studied usually at low temperatures, where the model parameters can be considered the same for different loadings). and Obsahuje seznam literatury
The paper introduces the test of aggregation as a simple, inexpensive method of evaluating suspension quality during drinking water treatment, suitable for use in both laboratory and operation conditions. The procedure and derivation of the aggregation test is described. The method is used for a demonstration of the influence of mean velocity gradient and mixing time on floc properties formed during the aggregation in a Couette reactor. It was proved that with increasing velocity gradient, the size of the aggregates present in the suspension decreases, and the suspension is substantially more homogeneous than with use of lower gradients. Further, it was confirmed that the size of aggregates reaches the steady state after a specific mixing time, which becomes shorter with increasing value of velocity gradient. and Příspěvek představuje test agregace jako jednoduchou a levnou metodu stanovení kvality suspenze při úpravě vody vhodnou pro použití v laboratorních i provozních podmínkách. Je popsán metodický postup i odvození testu agregace. Metoda je použita pro hodnocení vlivu středního gradientu rychlosti a doby míchání na vlastnosti vytvářených agregátů (vloček) při agregaci v Couettově reaktoru. Bylo prokázáno, že se vzrůstajícím gradientem se snižuje velikost agregátů přítomných v suspenzi a suspenze je značně více homogenní než při použití nízkých gradientů rychlosti. Dále bylo potvrzeno, že velikost agregátů dosahuje po určité době míchání stabilní hodnoty. Čas pro dosažení tohoto ustáleného stavu se zkracuje s rostoucí hodnotou použitého gradientu.
A simple method of a bicolor (multicolor), fast-Fourier, PAM chlorophyll fluorometry has been developed to obtain fluorescence induction curves. Quantum yields of PSII photochemistry were determined with blue and red simultaneously applied pulsed measuring lights for three subsequent 20-min periods of dark-, light-adaptation under actinic light and dark recovery. Measuring lights were cross-combined with blue and red actinic lights and saturation pulses. Coefficients of chromatic divergence were calculated as a ratio of the quantum yields obtained by red measuring light to that obtained by blue measuring light. Adaptation of Ficus benjamina and Hordeum vulgare leaves under blue (but not red) actinic light resulted in the sufficient increase of chromatic divergence. In addition, fraction of active, non(photo)inhibited, PSII centers was shown to be dependent on the color of measuring light. Thus, color of the light sources should be considered when reporting results of parameters evaluated from fluorescence induction curves., V. Lysenko, D. Lazár, T. Varduny., and Obsahuje bibliografii
Transients of chlorophyll fluorescence in photosynthetic objects are often measured using short pulses of exciting radiation, which has recently been employed to capture kinetic images of fluorescence at the macroscopic level. Here we describe an instrument introducing this principle to recording of two dimensional fluorescence transients in microscopic objects. A modified fluorescence microscope is equipped with a CCD camera intensified by a micro-channel plate image amplifier. The microscopic field is irradiated simultaneously by three types of radiation: actinic radiation, saturating flashes, and pulsed measuring radiation. The measuring pulses are generated by a light-emitting diode and their duration is between 10 to 250 µs. The detection of fluorescence images (300×400 pixels, 8 bit) has a maximum time resolution of 40 ms and is gated in synchrony with the exciting pulses. This allows measuring on a background of a continuous actinic radiation up to irradiance that can elicit the maximal fluorescence yield (FM). On the other hand, the integral irradiance of the objects by the measuring radiation is very low, e.g., 0.08 µmol m-2 s-1 at 0.05 µm spatial resolution and 0.006 µmol m-2 s-1 at 4 µm spatial resolution. This allows a reliable recording of F0 even in very short time intervals (e.g., 5×80 ms). The software yields fluorescence kinetic curves for objects in user-selected areas as well as complete false-colour maps of the essential fluorescence kinetics parameters (FM, FO, FV, FV/FM, etc.) showing a two-dimensional distribution of their values. Several examples demonstrate that records of fluorescence kinetics can be obtained with a reasonable signal-to-noise ratio with all standard microscope objectives and with object sizes reaching from segments of leaf tissue to individual algal cells or chloroplasts. and H. Küpper ... [et al.].
In the present study, a high percentage of Japanese anglerfish, Lophius litulon (Jordan, 1902), contained a microsporidian infection of the nervous tissues. Xenomas were removed and prepared for standard wax histology and transmission electron microscopy (TEM). DNA extractions were performed on parasite spores and used in PCR and sequencing reactions. Fresh spores measured 3.4 × 1.8 µm and were uniform in size with no dimorphism observed. TEM confirmed that only a single developmental cycle and a single spore form were present. Small subunit (SSU) rDNA sequences were >99.5% similar to those of Spraguea lophii (Doflein, 1898) and Glugea americanus (Takvorian et Cali, 1986) from the European and American Lophius spp. respectively. The microsporidian from the nervous tissue of L. litulon undoubtedly belongs in the genus Spraguea Sprague et Vávra, 1976 and the authors suggest a revision to the generic description of Spraguea to include monomorphic forms and the transfer of Glugea americanus to Spraguea americana comb. n. Since no major differences in ultrastructure or SSU rDNA sequence data exist between Spraguea americana and the microsporidian from the Japanese anglerfish, they evidently belong to the same species. This report of Spraguea americana is the first report of a Spraguea species from L. litulon and indeed from the Pacific water mass.
A new Microsporidium sp. infects Rhizophagus grandis Gyllenhall, a beetle which preys on the bark beetle Dendroctonus micans Kugellan in Turkey. Mature spores are single, uninucleate, oval in shape (3.75 ± 0.27 µm in length by 2.47 ± 0.13 µm in width), with a subapically fixed polar filament. The polar filament is anisofilar, coiled in 7-8 normal and 3-4 reduced coils. Other characteristic features of the microsporidium are the four/five nuclear divisions to form 16/32 (commonly 16) spores, subpersistent sporophorous vesicles (pansporoblasts) remaining till formation of the endospore, and the vesicles dissolved with free mature spores. The polaroplast is divided into three zones: an amorphous zone, dense layers, and a lamellar-tubular area extending to the central part of the spore.