The physiological and biochemical behaviour of rice (Oryza sativa, var. Jyoti) treated with copper (II) oxide nanoparticles (CuO NPs) was studied. Germination rate, root and shoot length, and biomass decreased, while uptake of Cu in the roots and shoots increased at high concentrations of CuO NPs. The accumulation of CuO NPs was observed in the cells, especially, in the chloroplasts, and was accompanied by a lower number of thylakoids per granum. Photosynthetic rate, transpiration rate, stomatal conductance, maximal quantum yield of PSII photochemistry, and photosynthetic pigment contents declined, with a complete loss of PSII photochemical quenching at 1,000 mg(CuO NP) L-1. Oxidative and osmotic stress was evidenced by increased malondialdehyde and proline contents. Elevated expression of ascorbate peroxidase and superoxide dismutase were also observed. Our work clearly demonstrated the toxic effect of Cu accumulation in roots and shoots that resulted in loss of photosynthesis., M. V. J. Da Costa, P. K. Sharma., and Obsahuje seznam literatury
In order to investigate the effect of day/night temperature difference (DIF) on photosynthetic characteristics of tomato plants (Solanum lycopersicum, cv. Jinguan 5) at fruit stage, an experiment was carried out in climate chambers. Five day/night temperature regimes (16/34, 19/31, 25/25, 31/19, and 34/16°C) with respective DIFs of -18, -12, 0, +12, and +18 were used and measured at mean daily temperature of 25°C. The results showed that chlorophyll (Chl) a, Chl b, net photosynthetic rate (PN), stomatal conductance (gs), maximum quantum yield of PSII photochemistry (Fv/Fm), effective quantum yield of PSII photochemistry (ϕPSII), and photochemical quenching (qp) significantly increased under positive DIF, while they decreased with negative DIF. In contrast, the Chl a/b ratio and nonphotochemical quenching (NPQ) decreased under positive DIF, while increased with negative DIF. Chl a, Chl b, PN, gs, Fv/Fm, ϕPSII, and qp were larger under +12 DIF than those at +18 DIF, while Chl a/b and NPQ showed an opposite trend., X. K. Yuan., and Seznam literatury
Spectroscopy was used to investigate the fluorescence quenching mechanism in light-harvesting complex 2 (LHC2). The 77 K fluorescence excitation spectroscopy was performed for detection of aggregation state of LHC2 treated with different concentrations of octylphenol poly(ethyleneglycol ether)10 (TX-100). Resonance Raman (RR) spectra excited with 488, 496, and 514 nm provided molecular configuration of neoxanthin, lutein 1, and lutein 2, respectively. At increased concentration of TX-100, the RR signals of xanthophylls were enhanced in the four frequency regions, which was accompanied with increase of fluorescence of chlorophyll (Chl) a. Thus the absorption of the three xanthophyll molecules was inclined to excitation wavelength, which proved that functional configurations of xanthophyll molecules in LHC2 were vital for fast transfer of excitation energy to Chl a molecules. Changes in the v4 region (C-H out-of-plane bending modes, at ∼960 cm-1 in RR spectra) demonstrated that the twist feature of neoxanthin, lutein 1, and lutein 2 molecules existed in LHC2 trimers, however, it was lost in the LHC2 macro-aggregates. In the second derivative absorption spectra of LHC2, neoxanthin absorption was not detected in LHC2 macro-aggregates, while evident absorption was found in LHC2 trimers and this absorption decreased obviously when TX-100 concentration was higher than 1 mM. Hence the neoxanthin molecule had a structural role in formation of LHC2 trimers. The RR and absorption spectra also implied that carotenoid molecules constructed the functional LHC2 trimers via their intrinsic configuration features, which enabled energy transfer to Chl a efficiently and led to lower fluorescence quenching efficiency. In contrast, these intrinsic twist configurations were lost in LHC2 macro-aggregates and led to lower energy transfer efficiency and higher fluorescence quenching efficiency. and Z. H. Hu, F. Zhou, C. H. Yang.
Relation of diabetes mellitus (DM) to the various stages of corneal nerve fiber damage is well accepted. A possible association between changes in the cornea of diabetic patients and diabetic retinopathy (DR), DM duration, and age at the time of DM diagnosis were evaluated. The study included 60 patients with DM type 1 (DM1) and 20 healthy control subjects. The density of basal epithelial cells, keratocytes and endothelial cells, and the status of the subbasal nerve fibers were evaluated using in vivo corneal confocal microscopy. Basal epithelial cell density increased with age (p=0.026), while stromal and endothelial cell density decreased with age (p=0.003, p=0.0005, p<0.0001). After the DM1 diagnosis was established, this association with age weaken. We showed nerve fiber damage in DM1 patients (p˂0.0001). The damage correlated with the degree of DR. DM1 patients with higher age at DM1 diagnosis had a higher nerve fiber density (p=0.0021). These results indicated that age at DM1 diagnosis potentially has an important effect on final nerve fiber and corneal cell density.
The objective of this study was to evaluate the effect of diet and 677 C®T mutation of the methylenetetrahydrofolate reductase (MTHFR) gene on plasma homocyst(e)ine concentrations in an adolescent population (113 males, age: 14.2±2.4 years; 202 females, age: 14.9±2.1 years) from a region characterized by high cardiovascular mortality. Homocyst(e)ine levels did not differ between males and females (9.4±3.5 and 8.9±3.1 mmol/l, respectively). The homozygosity for the 677 C®T MTHFR mutation was found in 4.6 % of subjects. No differences in homocyst(e)ine levels were found between MTHFR genotypes. Analysis of the diet composition which was performed on a 24-hour daily recall basis and a food frequency questionnaire showed a low daily intake of vitamin B6 (males: 1.13 mg/66 % RDA; females: 0.92 mg/61 % RDA). Daily folic acid intake was 0.21 g/105 % RDA in males and 0.23 g/115 % RDA in females. The results of our study show that the high homocyst(e)ine levels in the adolescent population were not affected by the 677 C®T MTHFR mutation. We conclude that an insufficient dietary intake of vitamin B6 and folic acid is responsible for this finding. This is in accord with the recommendation that the dietary allowances for folate should be reset to the originally prescribed levels of 0.4 g/day which should be sufficient to control the homocysteine levels., K. Rašlová, A. Bederová, J. Gašparovič, P. Blažíček, B. Smolková., and Obsahuje bibliografii
a1_The effect of different muscle shortening velocity was studied during cycling at a pedalling rate of 60 and 120 rev.min-1 on the [K+]v in 21 healthy young men (aged 22.5±2.2 years, body mass 72.7±6.4 kg, VO2max 3.720±0.426 l . min-1) performing an incremental exercise test until exhaustion. The power output increased by 30 W every 3 min, using an electrically controlled ergometer Ergoline 800S (see Zoladz et al. J. Physiol. 488: 211-217, 1995). The test was performed twice: once at a cycling frequency of 60 rev.min-1 (test A) and a few days later at frequency of 120 rev.min-1 (test B). At rest and at the end of each step (i.e. the last 15 s) antecubital venous blood samples for [K+]v were taken. Gas exchange variables were measured continuously (breath-by-breath) using Oxycon Champion Jaeger. The pre-exercise [K+]v in both tests was not significantly different amounting to 4.24±0.36 mmol.l-1 in test A, and 4.37±0.45 mmol.l-1 in test B. However, the [K+]v during cycling at 120 rev.min-1 was significantly higher (p<0.001, ANOVA for repeated measurements) at each power output when compared to cycling at 60 rev.min-1. The maximal power output reached 293±31 W in test A which was significantly higher (p<0.001) than in test B, which amounted to 223±40 W. The VO2max values in both tests reached 3.720±0.426 l.min-1 vs 3.777±0.514 l.min-1. These values were not significantly different. When the [K+]v was measured during incremental cycling exercise, a linear increase in [K+]v was observed in both tests. However, a significant (p<0.05) upward shift in the [K+]v and a % VO2max relationship was detected during cycling at 120 rev.min-1. The [K+]v measured at the VO2max level in tests A and B amounted to 6.00±0.47 mmol.l-1 vs 6.04±0.41 mmol.l-1, respectively., a2_This difference was not significant. It can thus be concluded that a) generation of the same external mechanical power output during cycling at a pedaling rate of 120 rev.min-1 causes significantly higher [K+]v changes than when cycling at 60 rev.min-1, b) the increase of venous plasma potassium concentration during dynamic incremental exercise is linearly related to the metabolic cost of work expressed by the percentage of VO2max (increase as reported previously by Vollestad et al. J. Physiol. Lond. 475: 359-368, 1994), c) there is a tendency towards upward shift in the [K+]v and % VO2max relation during cycling at 120 rev.min-1 when compared to cycling at 60 rev.min-1., J. A. Zoladz, K. Duda, J. Majerczak, P. Thor., and Obsahuje bibliografii
The influence of different leaf-to-fruit (l-t-f) ratios on leaf net photosynthetic rate (PN) and fruit characteristics in Olea europaea L. cv. Frantoio was evaluated in 2001 and 2002. In both years, at the end of June, at the end of July, and in mid-September (first, second, and third time of treatment, respectively), defoliation or fruit thinning were performed to give l-t-f ratios of 1/1, 3/1, 5/1, and 7/1 (about 5.1, 15.3, 25.6, and 35.8 cm2 of leaf area per fruit, respectively) on girdled and ungirdled peripheral shoots. PN showed substantial seasonal and diurnal variations. In ungirdled shoots, no differences due to the different l-t-f ratios were observed, whereas in girdled shoots PN tended to be lower in shoots with a high l-t-f ratio. In general, the values of leaf transpiration rate (E), stomatal conductance (gs), sub-stomatal CO2 concentration (Ci), and dark respiration rate (RD) were associated with those of PN. The starch and reducing sugar contents and area leaf dry mass (ADM) tended to be higher in leaves on girdled shoots with high l-t-f ratio, whereas in ungirdled shoots no differences related to the different l-t-f ratios were observed. The higher saccharide content in the leaves and the lower PN, in the presence of a high Ci, observed in girdled shoots with a high l-t-f ratio suggests that the depression in PN in these shoots may be the result of a feedback inhibition of the photosynthetic mechanism that regulates such a process. The l-t-f ratio did not have a substantial effect on fruit drop. In ungirdled shoots, the different l-t-f ratios did not produce significant differences in terms of fruit growth and leaf dry matter and saccharide contents, whereas in girdled shoots fruit growth increased as the l-t-f ratio increased, particularly when treatments were applied at the initial stage of fruit development. The percentage of oil in the pulp, on a dry matter basis, was not substantially influenced by girdling and l-t-f ratio. The abundant availability of assimilates seemed to cause earlier fruit ripening and, at the same time, retard fruit senescence (fruit detachment force). Shoot growth was slightly reduced by girdling. The abundant availability of assimilates, induced by girdling associated with high l-t-f ratio, stimulated flower induction. and P. Proietti, L. Nasini, F. Famiani.
The effects of metabolisable sugars sucrose and glucose along with non-metabolisable isomers of sucrose palatinose and turanose were tested. Rate of oxygen evolution (P), electron transport rate (ETR), and photochemical quenching (qp) showed substantial decrease after 24 and 48 h by glucose and sucrose treatments, whereas there was no effect on all these parameters by the treatment with palatinose and turanose. Also the Fv/Fm ratio remained constant through the time of studies revealing that the maximal photochemical capacity of the cells was unchanged. Non-photochemical quenching (qN) showed a decrease compared to the control values by all the treatments. Hence P and Chl fluorescence parameter were affected only by those sugars which are used in the metabolic pathways and not by sugar analogues. and A. K. Sinha, T. Roitsch.
The rubber tree (Hevea brasiliensis) is an important tropical crop with a high economic value that has been successfully cultivated in Xishuangbanna, China. Xishuangbanna has a long dry season (November-February) with cold nights and frequent fog events. Thus, it is important to select chilling-tolerant cultivars in order to understand better the role of fog in protecting rubber tree from chilling-induced photodamage. In this study, we examined the photosynthetic responses of six rubber tree cultivars (Lan 873, Yunyan 77-2, Yunyan 77-4, GT1, Reken 523, and Reyan 733-97) to night-chilling stress (0, 5, and 10°C) and two different irradiances (100 and 50% of full sunlight). Our results showed that all six cultivars could withstand nights at 10°C for three days, while night chilling at 0 and 5°C impaired photosynthesis, which was indicated by photoinhibition, decrease of soluble protein content, and accumulation of malondialdehyde. Reken 523 and Reyan 733-97 were more sensitive to night chilling than other cultivars. Low irradiance (50% of full sunlight) after the chilling treatment apparently mitigated the effect of night-chilling stress. It indicates that frequent fog events after cold nights might greatly contribute to the success of rubber tree cultivation in Xishuangbanna., Y.-H. Tian, H.-F. Yuan, J. Xie, J.-W. Deng, X.-S. Dao, Y.-L. Zheng., and Seznam literatury
We investigated net photosynthetic rate (PN) of ear and two uppermost (flag and penultimate) leaves of wheat cultivars Hongmangmai (drought resistant) and Haruhikari (drought sensitive) during post-anthesis under irrigated and non-irrigated field conditions. The PN of ear and flag leaf were significantly higher and less affected by drought in Hongmangmai than in Haruhikari. The rate of reduction in stomatal conductance (gs) was similar for the two cultivars, but intercellular CO2 concentration (Ci) in the flag leaf of Hongmangmai was lower than that of Haruhikari in non-irrigated treatment. No differences were observed in leaf water potential (ψ1) and osmotic adjustment of the flag leaf of the cultivars. These results imply that differences in photosynthetic inhibition on the flag leaf at low leaf ψ1 between the cultivars were primarily due to non-stomatal effects. Hence the main physiological factor associated with yield stability of Hongmangmai under drought stress may be attributed to the capacity for chloroplast activity in the flag leaf, which apparently allows sustained PN of flag leaf during grain filling under drought stress. The higher PN of ear in Hongmangmai under drought could also be related to its drought resistance. and T. Inoue ... [et al.].