CO2 (40, 200, 400 loM) was added to the root systém of 10-d-old pea plants (Pisum sativum L. cv. Ran). The Co2'''-excess caused a reduction in the plant fresh and diy masses and water and chlorophyll contents. The rates of photosynthesis and transpiration decreased, while proline content and stomata resistance increased. The dramatic effect of Co2+-toxicity was expressed both in an inhibition of ribulose 1,5- bisphosphate (RuBP) carboxylase activity and a stimulation of RuBP-oxygenase and phosphoenolpyruvate carboxylase activities on the 4‘h day of cnltivation of plants in a solution of 400 pM C6^*.
Measurements of Sorbus stomata size and density, maximal photochemical efficiency of photosystem II (Fv/Fm),
variable-to-initial fluorescence ratio (Fv/F0) and potential electron acceptor capacity (‘area’) were performed during leaf development in four parental diploid species, S. aria, S. aucuparia, S. chamaemespilus, S. torminalis, and two hybrid species, S. hazslinszkyana and S. intermedia. In fully expanded mature leaves, stomata lengths and densities were significantly larger in the shrub S. chamaemespilus than in the five tree species. The best performance of both the Fv/Fm and the Fv/F0 ratio was recorded in S. intermedia, whereas S. chamaemespilus had the highest value of ‘area’. From a physiological point of view, the results of this study showed that the photosystem II reaction centers remained intact functionally through all phenological stages of leaf expansion for all examined species of Sorbus., I. Čaňová ... [et al.]., and Obsahuje bibliografii
The role of the cortico-tectal pathways in the processing of auditory signals was investigated by recording the click-evoked responses and extracellular multiple unit activity in the inferior colliculus (IC) after functional ablation of the auditory cortex (AC) by local intracortical application of a sodium channel blocker, tetrodotoxin (TTX). Click-evoked IC responses (IC-ER) and multiple unit activity in response to tone bursts were recorded with implanted electrodes in the IC of rats lightly anaesthetized with xylazine. Neural activity was recorded before and after the application of TTX into the ipsilateral auditory cortex (AC) through three implanted cannulas in a total dose of 30 ng. The functional status of the AC was monitored by recording click-evoked middle latency responses from a ball electrode implanted on the AC. During inactivation of the AC, IC-ER amplitudes were either increased (48 % of the cases), decreased (32 % of the cases) or not evidently changed (20 % of the cases). Corresponding effects were observed in the firing rate of IC neurons. Functional ablation of the AC also resulted in a significant prolongation of the latencies of individual waves of the IC-ER. However, the discharge pattern of the multiple unit responses, response thresholds and tuning were not altered during AC inactivation. IC neural activity recovered within several hours, and maximally during 2 days. The results reveal principles of the interaction of cortico-tectal pathways with IC neuronal activity., F. C. Nwabueze-Ogbo, J. Popelář, J. Syka., and Obsahuje bibliografii
Postnatal heart development is characterized by critical periods of heart remodeling. In order to characterize the changes in the lipophilic fraction induced by free radicals, fatty acids and t heir oxidized products, lipofuscin -like pigments (LFP), were investigated. Fatty acids were analyz ed by gas chromatography and LFP were studied by fluorescence techniques. A fluorophore characterized by spectral methods was further resolved by HPLC. Major changes in the composition of fatty acids occurred immediately after birth and then during maturation. Fluorescence of LFP changed markedly on postnatal days 1, 4, 8, and 14, and differed from the adult animals. LFP comprise several fluorophores that were present since fetal state till adulthood. No new major fluorophores were formed during development, just the abundances of individual fluorophores have been modulated which produced changes in the shape of the spectral arrays. HPLC resolved the fluorophore with excitation maximum at 360 nm and emission maximum at 410 nm. New chromatographically distinct species appeared immediately on postnatal day 1, and then on days 30 and 60. Consumption of polyunsaturated fatty acids immediately after birth and subseque nt formation of LFP suggests that oxidative stress is involved in normal heart development., J. Wilhelm, J. Ivica, Z. Veselská, J. Uhlík, L. Vajner., and Obsahuje bibliografii
Rice (Oryza sativa L.) plants were grown in nutríent solutíon containing concentrations of Cu vaiying from deficiency to toxicity [0.002-6.25 g(Cu) m"^]. Shoot contents of Cu, Mn and Fe were measured as well as the concentrations of plastocyanin (PC), plastoquinone (PQ) and cytochromes (cyt) f, 6553, 6-559up, and b- 559hp. While Cu concentration increased wilh increasing levels of metal in the solutíon, Mn and Fe concentrations progressively decreased after Cu treatments higher than 0.05 g m‘3. On a chlorophyll basis, the contents of PC and cyt/decreased after the 0.01 g(Cu) m'^ Cu treatonent, while the contents of cyt f>-559Lp and b- 559hp did not show any apparent conelatíon, and the PQ concentration sharply increased with increasing Cu toxicity. Membrane permeability and acid RNAse activity were enhanced with increasing Cu concentration.
Nitric oxide (NO) may play a role in the pathophysiology of excitotoxicity. It is also possible that increase in Ca2+ overload and NO-mediated events are involved in neuronal loss during excitotoxicity. Using nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry, we have investigated the effects of melatonin on NADPH-d positive hippocampal neurons after kainic acid (KA) induced excitotoxicity in female rats of Wistar strain. Cytosolic Ca2+ (free calcium) in all the respective experimental groups was also studied. Kainic acid was administered, with a single dose of 10 mg/kg/bw (body weight) to the animals. KA treated rats were given melatonin at a dose of 20 mg/kg/bw (for 14 day). On the last day of treatment, animals were transcardially perfused with 4 % paraformaldehyde under deep thiopental anaesthesia. Cryostat sections (20 µm) were cut and stained for NADPH-d positive neurons. KA exposed animals showed a significantly increased number of NADPH-d positive neurons in the dorsal and ventral blade of the dentate gyrus (DG), hilus, CA1 and CA3 area of hippocampus, with a parallel increase in intracellular free Ca2+ ion concentration, as compared to the control group. KA + melatonin-treated animal groups showed reduced number of NADPH-d positive neurons in DG, hilus, CA1 and CA3 areas and a decline in cytosolic Ca2+ concentration, as compared to KA treated group. Our study suggests that the enhanced levels of cytosolic Ca2+ and nitric oxide (NO) play an important role in kainate induced excitotoxicity. Inhibition of NO production may be another means whereby melatonin can reduce oxidative damage and seems to play important role in neuroprotection., A. Jain, ... [et al.]., and Obsahuje seznam literatury
The endometrium acquires the ability to implant a hatched blastocyst only within a specific time termed the receptive phase. Ovarian steroid hormones are essential for structural and functional changes that prepare the endometrium to be receptive. Pinopodes have been suggested to be markers of uterine receptivity. The aim of this study was to compare the pinopode expression and serum levels of ovarian steroid hormones in the mid-luteal phase of the natural cycle and in a “mock” cycle in the same subject. Sequentional endometrial biopsies within 48 hours were obtained from women in the mid-luteal phase (ovulation +5, ovulation +7) of the natural cycle and in the “mock” cycle (progesterone supplementation +5 and +7). Biopsies were examined under a scanning electron microscope for pinopode detection. The expression of pinopodes was similar in both cycles, where pinopodes covered about 5 % of the endometrial surface. The developmental stages were also similar with a slight increase of fully developed pinopodes in both samples in the “mock” cycles. Our findings suggest that hormonal preparation of the endometrium do not change the timing of pinopode expression.
Fluorescence excitation spectra of different protochlorophyll(ide) (PChlide) a forms in intact etiolated cucumber cotyledons showed a pronounced increase in intensity of the 390 nm band in comparison with spectra of the pigment in Solutions. The native PChlide F657 also had an additional band at 360 nm in its excitation spectra, which disappeared after leaf homogenization and was restored by addition of dithionite. The restoration correlated with changes around 340 nm in the excitation spectrum of blue-green fluorescence. In consideration of this fact, the 360 nm band seems to correspond to energy transfer from NADPH to PChlide a. After the onset of irradiation a new band appeared at 380 nm in the excitation spectrum of the main pigment fluorescence, which was very similar to that found in the absorption spectinm of isolated Chl a. Moreover, in the Soret region the excitation spectrum had a double band splitting which disappeared only after the Shibata shift, simultaneously with the disappearance of the 360 nm band. Besides the well-known PChl(ide) F633, F642, and F657 forms, etiolated cucumber cotyledons háve emission at 673 nm. Its excitation spectrum was hardly distinguishable from the PChlide F657 fluorescence excitation spectrum in etiolated samples. In the irradiated plants this band had excitation spectrum of monomeric Chl a. The intensity of band at 673 run decreased and transiently increased after PChlide photoconversion. The dynamics of these fluorescence intensity changes under inadiation showed positive correlation both with PChlide F657 and with PChl(ide) F642, indicating the short wavelength Chl a preexistence in etiolated plants and its additional formation after the onset of irradiation.
Non-photochemical quenching of chlorophyll fluorescence (qN) and its three components (qNf, qNm, and qNs) in the flag leaves of wheat grown in the field were studied by a fluorometer PAM-2000 on clear days. The diurnal variation patterns of qN in just fully extended (JFEL) and aging leaves (AL) were similar, but qNm declined markedly in JFEL while it remained at a relatively high level in AL under strong sunlight at noon. Furthermore, at midday qNf was higher than qNs in JFEL, but much lower in AL. The results show the relative contributions of different mechanisms in preventing the photosynthetic apparatus from photodamage change during leaf development. and S.-S. Hong ... [et al.].