The correlation between baroreflex sensitivity (BRS) and the spectrum component at a frequency of 0.1 Hz of pulse intervals (PI) and systolic blood pressure (SBP) was studied. SBP and PI of 51 subjects were recorded beat-to-beat at rest (3 min), during exercise (0.5 W/kg of body weight, 9 min), and at rest (6 min) after exercise. BRS was determined by a spectral method (a modified alpha index technique). The subjects were divided into groups according to the spectral amplitude of SBP at a frequency of 0.1 Hz. The following limits of amplitude (in mm Hg) were used: very high ≥ 5.4 (VH); high 5.4 > H ≥ 3 (H); medium 3 > M ≥ 2 (M), low < 2 (L). We analyzed the relationships between 0.1 Hz variability in PI and BRS at rest, during the exercise and during recovery in subgroups VH, H, M, L. The 0.1 Hz variability of PI increased significantly with increasing BRS in each of the groups with identical 0.1 Hz variability in SBP. This relationship was shifted to the lower values of PI variability at the same BRS with a decrease in SBP variability. The primary SBP variability increased during exercise. The interrelationship between the variability of SBP, PI and BRS was identical at rest and during exercise. A causal interrelationship between the 0.1 Hz variability of SBP and PI, and BRS was shown. During exercise, the increasing primary variability in SBP due to sympathetic activation was present, but it did not change the relationship between variability in pulse intervals and BRS., N. Honzíková, A. Krtička, Z. Nováková, E. Závodná., and Obsahuje bibliografii
A differential mechanical technique for tissue separation, based on the different physical resistance to grinding between mesophyll (M) and bundle sheath (BS) cells, was tested on dicotyledonous C4 plants A triplex canscens, A triplex halimus, Gomphrena globosa, Amaranthus retroflexus, Amaranthus caudatus and Portulaca oleracea. A metal sieve (35 mesh) was placed inside a mortar and pieces of leaves (0.5 cm2) were ground in an aqueous medium on the sieve to obtain a homogenate. The homogenate was at first collected below the sieve and was then filtered through six layers of muslin. Microscopic examination showed that the filtrate was enriched by the M cells and the residue was enriched by BS cells, few of which were broken. The BS cell fraction was then vigorously ground and filtered; this second filtrate was named the BS cell fraction and the first filtrate was named the M cell fraction. Ribulose 1,5-bisphosphate carboxylase (EC 4.1.1.39) (RuBPC) and phosphoenolpyruvate carboxylase (EC 4.1.1.31) (PEPC) were assayed, and chlorophyll determinations and protein estimations were made on both fractions. As expected, PEPC showed higher activities in the M fractions; contrary to expectation RuBPC was present in M cell fractions in the six dicotyledonous C4 plants tested. The relative high RuBPC activities found in the M fraction could not be explained in terms of bundle sheath contamination.
The absolute gravity measurements are an important tool for reliable monitoring geodynamic phenomena. Based on the experience with the absolute gravimeter FG5#215 (gravimeter of the Center for Earth Dynamics Research), the accuracy of FG5 absolute gravimeters is presented in this study. The instrumental reproducibility of this meter is characterized by the value of 0.7 μGal. Discussed are important environmental effects on gravity measurements, such as atmospheric and hydrological effects, understanding of which is necessary for correct and reliable interpretation of the repeated absolute gravity measurements in geodynamics., Vojtech Pálinkáš, Jakub Kostelecký and Jaroslav Šimek., and Obsahuje bibliografii
An unexpectedly large proportion of C4 grasses was found in a moderately temperate and moist Himalayan location during monsoon period. 79 % of total grasses occurring in the area were found to be C4. Several grasses hitberto unreported as C4 háve now been recorded. The principál cause for the natural abundance of C4 species is presumably low atmospheric CO2 levels rallua' tlian the aridity and warmer temperatures. The finding adds a new dimension to our knowledge of natural distribution of the C4 species.
The Northern pine processionary moth, Thaumetopoea pinivora (Treitschke, 1834) shows a highly scattered distribution with fragmented populations across Europe. A previous study exploring the postglacial history of T. pinivora defined it as a cold-tolerant relict species and concluded that a progressive reduction of suitable habitats after the postglacial expansion from refugia in the southern Iberian peninsula best explained the distribution and genetic structure of populations of this species. However, recent records, both by us and others, challenge this view. Surprisingly, some of the newly found populations from southern Spain use black pine, Pinus nigra J.F. Arnold as a host plant despite the fact that the typical host of the species, Scots pine, Pinus sylvestris L. occurs in the area. We provide genetic data for one of these recently found southern populations where the larvae feed on P. nigra, and compare this with previously published data on individuals collected on P. sylvestris. This data reveals that populations from different host trees are no more genetically differentiated than populations sharing the same host plant. The findings of a wider diet breadth open the way to widen the search for the still unidentified glacial refugium of T. pinivora, and as such may contribute to a better understanding about how the species has spread across Europe., José A. Hódar, Anna Cassel-Lundhagen, Andrea Battisti, Stig Larsson., and Obsahuje bibliografii
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 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
Modelling the exchange and transformation of matter and energy in ecosystems requires the development of hierarchical structured models of the considered ecosystem compartments. In this context, a model describing the coupled CO2 and H2O gas exchange of a winter wheat canopy was developed and calibrated. The formidation of the model was related to the problems of linking processes at different systém levels. For model calibration, ecophysiological gas exchange characteristics and micro-meteorological data were obtained on both leaf and canopy levels and completed by results of structural and Chemical plant analysis. The gas exchange was measured by a computer-controlled multi-channel systém. On the basis of this data pool, the canopy gas fluxes were calculated by the model as the integrál of the corresponding local fluxes over the area elements of the canopy. The model describes correctly physiological interactions and gas exchange characteristics at both the leaf and canopy levels.