The present study was conducted to determine the effect of exogenous application of brassinolide (BR) on Leymus chinensis grown under shade, i.e., control (100% natural light), mild shade (70% natural light), and moderate shade (50% natural light). Shade substantially enhanced the plant growth, synthesis of photosynthetic pigments, photosynthetic efficiency, and chlorophyll (Chl) fluorescence attributes of L. chinensis as compared with control. The order of increase was mild shade > moderate shade > natural light except Chl content, where the order of increase was moderate shade > mild shade > natural light. Likewise, application of BR resulted in further exacerbation of plant height, plant fresh and dry mass, but less in case of Chl and carotenoids contents, gas-exchange characteristics, and Chl fluorescence attributes. The results conclude that shade significantly enhanced plant growth through alterations in physiological attributes of L. chinensis, while, application of BR may not further improve the plant growth under shade., A. J. Yang, S. A. Anjum, L. Wang, J. X. Song, X. F. Zong, J. Lv, A. Zohaib, I. Ali, R. Yan, Y. Zhang, Y. F. Dong, S. G. Wang., and Obsahuje bibliografii
On the first day after foliar application, chitosan pentamer (CH5) and chitin pentamer (CHIT5) decreased net photosynthetic rate (PN) of soybean and maize, however, on subsequent days there was an increase in PN in some treatments. CH5 caused an increase in maize PN on day 3 at 10-5 and 10-7 M; the increases were 18 and 10 % over the control plants. This increase was correlated with increases in stomatal conductance (gs) and transpiration rate (E), while the intercellular CO2 concentration (Ci) was not different from the control plants. PN of soybean plants did not differ from the control plants except for treatment CH5 (10-7 M) which caused an 8 % increase on day 2, along with increased gs, E, and Ci. On days 5 and 6 the CHIT5 treatment caused a 6-8 % increase in PN of maize, which was accompanied by increases in gs, E, and Ci. However, there was no such increase for soybean plants treated with CHIT5. In general, foliar application of high molecular mass chitin (CHH) resulted in decreased PN, particularly for 0.010 % treated plants, both in maize and soybean. Foliar applications of chitosan and chitin oligomers did not affect (p > 0.05) maize or soybean height, root length, leaf area, shoot or root or total dry mass. and W. M. Khan, B. Prithiviraj, D. L. Smith.
The effect on traits of photosynthesis and water relations of assimilate demand was studied in olive tree that has strong alternate bearing. The diurnal and seasonal leaf gas exchanges, area dry mass, and saccharide and chlorophyll (Chl) contents were measured by comparing shoots with fruit of "on-trees" (heavy fruit load) with shoots without fruit on both "on-trees" and "off-trees" (light fruit load). In spite of large seasonal and diurnal differences, leaf net photosynthetic rate (PN), stomatal conductance (gs), sub-stomatal CO2 concentration (C1), transpiration rate (E), and respiration rate (RD) were not significantly influenced by fruit load or by the presence or absence of fruit on the shoot. An only exception was at the beginning of July when the one-year-old leaves on shoots with fruit had slightly higher PN and E than leaves on shoots without fruit. Water content, Chl and saccharide contents, and area dry mass of the leaf were not substantially influenced by the presence/absence of fruit on the shoot or fruit load. Hence the sink demand, associated with fruit growth, did not improve leaf photosynthetic efficiency in olive.
Activation of GABAB receptors leads to longer inhibitory postsynaptic potentials than activation of GABAA receptors. Therefore GABAB receptors may be a target for anticonvulsant therapy. The present study examined possible effects of GABAB receptor agonist SKF97541 on cortical and hippocampal epileptic afterdischarges (ADs). Epileptic ADs elicited by electrical stimulation of sensorimotor cortex or dorsal hippocampus were studied in adult male Wistar rats. Stimulation series were applied 6 times with 10- or 20-min interval. Either interval was efficient for reliable elicitation of cortical ADs but stimulation at 10-min intervals did not reliably elicit hippocampal ADs, many stimulations were without effect. SKF97541 in dose 1 mg/kg significantly prolonged cortical ADs. Duration of hippocampal ADs was not significantly changed by either dose of SKF97541 in spite of a marked myorelaxant effect of the higher dose. Our present data demonstrated that neither cortical nor hippocampal ADs in adult rats were suppressed by GABAB receptor agonist SKF97541. Proconvulsant effect on cortical ADs indicates a different role in these two brain structures. In addition, duration of refractory period for electrically-induced ADs in these two structures in adult rats is different., P. Fábera, P. Mares., and Obsahuje bibliografii
Agronomic traits, photosynthetic pigments, gas exchange, and chlorophyll (Chl) fluorescence parameters of red stem buckwheat (Fagopyrum dibotrys Hara) mutants induced by γ-radiation were compared with green control at seedling stage. Plant height, number of first-class branches, and rhizome biomass were inhibited significantly (p<0.01). Chl a, Chl b, and Chl a+b contents decreased with elevated dose of γ-rays, while increasing carotenoid content indicated that buckwheat was capable of adjusting to the radiation damage. Decrease in net photosynthetic rate was the result of both stomatal and non-stomatal limitations. Fluorescence parameters, such as F0, Fm, Fv/Fm, Fv/F0, ΦPS2, electron transport rate, and photochemical quenching declined significantly (p<0.01) as compared with control due to photoinhibition, while non-photochemical quenching increased to enhance thermal dissipation. Lower parameters implied that leaf tissue was damaged significantly by high dose of γ-radiation and therefore leaf senescence was accelerated. and C. F. Jia, A. L. Li.
The present study was undertaken to investigate the effect of Glomus mosseae on chlorophyll (Chl) content, Chl fluorescence parameters and chloroplast ultrastructure of beach plum seedlings under 2% NaCl stress. The results showed that compared to control, both Chl a and Chl b contents of NaCl + G. mosseae treatment were significantly lower during the salt stress, while Chl a/b ratio increased significantly. The increase of minimal fluorescence of darkadapted state (F0), and the decrease of maximal fluorescence of dark-adapted state (Fm) and variable fluorescence (Fv) values were inhibited. The maximum quantum yield of PSII photochemistry (Fv/Fm), the maximum energy transformation potential of PSII photochemistry (Fv/F0) and the effective quantum yield of PSII photochemistry (ΦPSII) increased significantly, especially the latter two variables. The values of the photochemical quenching coefficient (qP) and the nonphotochemical quenching (NPQ) were similar between G. mosseae inoculation and noninoculation. It could be concluded that G. mosseae inoculation could protect the photosystem II (PSII) of beach plum, enhance the efficiency of primary light energy conversion and improve the primitive response of photosynthesis under salinity stress. Meanwhile, G. mosseae inoculation was beneficial to maintain the integrity of thylakoid membrane and to protect the structure and function of chloroplast, which suggested that G. mosseae can alleviate the damage of NaCl stress to chloroplast., X. M. Zai ... [et al.]., and Obsahuje bibliografii
Cyanobacterial NDH-1 interacts with PSI to form NDH-1-PSI supercomplex. CpcG2, a linker protein for the PSI-specific peripheral antenna CpcG2-phycobilisome, is essential for stabilization of the supercomplex. Green light (GL) increased the expression of CpcG2 but had little effect, if any, on the expression of NDH-1 and PSI, when compared to the abundance of these components under red light (RL). The increased expression of CpcG2 intensified the band of NDH-1-PSI supercomplex after blue-native gel electrophoresis of the thylakoid membrane, possibly by stabilizing the supercomplex. The activity of NDH-1-dependent cyclic electron transport around PSI increased when cells grown under RL were transferred to a low intensity GL but was suppressed when cells were grown under high intensities of GL. The functionality of PSI showed the same trend. We thus conclude that GL increases the expression of CpcG2, thereby increasing the abundance of the NDH-1-PSI supercomplex and its activity at low GL but not at higher GL., F. Gao, T. Ogawa, W. Ma., and Obsahuje bibliografické odkazy
The role of neuroendocrine responsiveness in the development of orthostatic intolerance after bed rest was studied in physically fit subjects. Head-down bed-rest (HDBR, -6 degrees, 4 days) was performed in 15 men after 6 weeks of aerobic training. The standing test was performed before, after training and on day 4 of the HDBR. Orthostatic intolerance was observed in one subject before and after training. The blood pressure response after training was enhanced (mean BP increments 18±2 vs. 13±2 mm Hg, p<0.05, means ± S.E.M.), although noradrenaline response was diminished (1.38±0.18 vs. 2.76±0.25 mol.l-1, p<0.01). Orthostatic intolerance after HDBR was observed in 10 subjects, the BP response was blunted, and noradrenaline as well as plasma renin activity (PRA) responses were augmented (NA 3.10±0.33 mol.l-1, p<0.001; PRA 2.98±1.12 vs. 0.85±0.15 ng.ml-1, p<0.05). Plasma noradrenaline, adrenaline and aldosterone responses in orthostatic intolerant subjects were similar to the tolerant group. We conclude that six weeks of training attenuated the sympathetic response to standing and had no effect on the orthostatic tolerance. In orthostatic intolerance the BP response induced by subsequent HDBR was absent despite an enhanced sympathetic response., J. Koška, L. Kšinantová, R. Kvetňanský, M. Marko, D. Hamar, M. Vigaš, R. Hatala., and Obsahuje bibliografii
In two winter wheat (Triticum aestivum L.) cultivars differing in their response to high temperature, JD8 (tolerant) and J411 (sensitive) we studied the effect of heat stress on the activities of phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase (RuBPC) in green organs during grain-filling. There were significantly higher PEPC activities and lower RuBPC activities in each of the non-leaf organs (awn, glume, lemma, peduncle, and sheath) than in the flag leaf blade. Under heat stress for 12 d, the activity of RuBPC quickly declined and the activity of PEPC first increased and later declined in all organs, resulting in a great increase of the PEPC/RuBPC ratios in the organs, particularly in non-leaf organs which had a higher PEPC/RuBPC than the flag leaf blade in all times. The PEPC activity and PEPC/RuBPC ratio in every organ of JD8 were higher than those in the same organ of J411. Thus the differences in PEPC activities and PEPC/RuBPC may be associated with the differences in photosynthetic heat tolerance among the organs of the same plant or between the two cultivars. and X. L. Xu, Y.-H. Zhang, Z.-M. Wang.
High irradiance (HI) and high temperature (HT) increased in chloroplasts the content of monogalactosyldiacylglycerol (MGDG) and decreased the contents of digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG), and phosphatidylinositol (PI). HI and HT accelerated the transformation of DGDG to MGDG. The contents of unsaturated fatty acids in chloroplasts increased, while those of saturated fatty acids decreased. The contents of total carotenoids, neoxanthin, violaxanthin, lutein, and β-carotene increased first, then decreased. The content of chlorophyll decreased. HI caused the unfolding of thylakoids that was not resumed after a 72-h recovery. and F. Y. Liao, H. M. Li, P. He.