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2. Enhanced photosystem 2 thermostability during leaf growth of Elm (Ulmus pumila) seedlings
- Creator:
- Jiang, C.-D., Jiang, G.-M., Wang, X., Li, L.-H., Biswas, D. K., and Li, Y.-G.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll a fluorescence, JIP-test, leaf growth, and thermostability of photosystem 2
- Language:
- Multiple languages
- Description:
- We examined photosynthetic activities and thermostability of photosystem 2 (PS2) in leaves of elm (Ulmus pumila) seedlings from initiation to full expansion. During leaf development, net photosynthetic rate (PN) increased gradually and reached the maximum when leaves were fully developed. In parallel with the increase of PN, chlorophyll (Chl) content was significantly elevated. Chl a fluorescence measurements showed that the maximum quantum yield of PS2 (ϕPS2), the efficiency a trapped exciton, moved an electron into the electron transport chain further than QA- (Ψo), and the quantum yield of electron transport beyond QA (ϕEo) increased gradually. These results were independently confirmed by our low irradiance experiments. When subjected to progressive heat stress, the young leaves exhibited considerably lower ϕPS2 and higher minimal fluorescence (F0) than the mature leaves, revealing the highly sensitive nature of PS2 under heat in the newly initiating leaves. Further analysis showed that PS2 structure in the newly initiating leaves was strongly altered under heat, as evidenced by the increased fluorescence signals at the position of the K step. We therefore demonstrated an inhibition in the oxygen-evolving complex (OEC) in the young leaves. This resulted in decrease in amount of the functional PS2 reaction centres and relative increase in the PS2 reaction centres with inhibited electron transport at the acceptor side under heat. We suggest that the enhanced thermostability of PS2 during leaf development is associated with improved OEC stability. and C.-D. Jiang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Interaction of salicylic acid and ethylene and their effects on some physiological and biochemical parameters in canola plants (Brassica napus L.)
- Creator:
- Tirani, M. M., Nasibi, F., and Kalantari, Kh. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, lipid peroxidation, oxidative stress, phenolic compound, photosynthetic pigments, 2, and 581
- Language:
- Multiple languages
- Description:
- Environmental stresses, such as cold, heat, salinity, and drought, induce ethylene production and oxidative stress and cause damage in plants. On the other hand, studies have shown that salicylic acid (SA) induced resistance to environmental stresses in plants. In this research, the effects of ethylene on chlorophyll (Chl), carotenoid (Car), anthocyanin, flavonoids, ascorbic acid, dehydroascorbic acid, total ascorbate, lipid peroxidation, and ethylene production in leaves of canola pretreated with SA were studied. The plants were grown in pots until they have four leaves. Leaves were sprayed for two days with three different concentrations of SA (0, 0.5, and 1 mM). The plants were treated for three days with three concentrations of ethylene (0, 50, and 100 ppm). At the end of the ethylene treatments, all examined parameters were measured. The results showed that the ethylene treatments induced lipid peroxidation, while SA mitigated this effect. The ethylene treatment lowered significantly Chl and Car contents and anthocyanin accumulation, but SA alleviated these effects. SA induced an increase in ascorbic acid content in canola plants after the ethylene treatments. Therefore, we concluded that SA played an important role in the alleviation of damages caused by stress conditions. and M. M. Tirani, F. Nasibi, Kh. M. Kalantari.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. New mathematical and computational model of elastic continuum interaction with liquid
- Creator:
- Pochylý, František and Malenovský, Eduard
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- free damped vibration, real liqiud, interaction of continuum with liquid, and finite element
- Language:
- English
- Description:
- This contribution is focused on the analysis of dynamic behavior of elastic continuum moving in liquid. The method of solution is demonstrated on the non-stationatr movement of a bar in a real, incompressible liquid. The principle of the solution is based on the modal transformation of the bar and discrete process using the finite element method (FEM). The problem is in general non-linear. However, the method introduced in this contribution allows the solution which provides gradual separation of the movement of liquid and the movement of the bar. This substitution is entered analogously on the finite element and is dependent on the normal coordinates. The result is a tensor of additional effects. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
5. Observability of nonlinear systems
- Creator:
- Knobloch, H. W.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- ordinary differential equations and observability
- Language:
- English
- Description:
- Observability of a general nonlinear system—given in terms of an ODE x˙ = f(x) and an output map y = c(x)—is defined as in linear system theory (i.e. if f(x) = Ax and c(x) = Cx). In contrast to standard treatment of the subject we present a criterion for observability which is not a generalization of a known linear test. It is obtained by evaluation of “approximate first integrals”. This concept is borrowed from nonlinear control theory where it appears under the label ''Dissipation Inequality'' and serves as a link with Hamilton-Jacobi theory.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
6. Temperature and light dependence of photosynthetic activities in wheat seedlings grown in the presence of DCMU [3-(3,4-dichlorophenyl)-1,1-dimethylurea]
- Creator:
- Muthuchelian, K., Bertamini, M., and Nedunchezhian, N.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, donor side, electron transport, photosystem, thylakoid membrane proteins, and Triticum
- Language:
- Multiple languages
- Description:
- Photosynthetic electron transfer was studied in thylakoids isolated from control and DCMU-grown wheat (Triticum aestivum L.) seedlings. When exposed to high temperature (HT) and high iradiance (HI), thylakoids showed large variations in the photosynthetic electron transport activities and thylakoid membrane proteins. A drastic reduction in the rate of whole electron transport chain (H2O → MV) was envisaged in control thylakoids when exposed to HT and HI. Such reduction was mainly due to the loss of photosystem 2, PS2 (H2O → DCBQ) activity. The thylakoids isolated from seedlings grown in the presence of DCMU showed greater resistance to HT and HI treatment. The artificial exogenous electron donors MnCl2, DPC, and NH2OH failed to restore the HI induced loss of PS2 activity in both control and DCMU thylakoids. In contrast, addition of DPC and NH2OH significantly restored the HT induced loss of PS2 activity in control thylakoids and partially in DCMU thylakoids. Similar results were obtained when Fv/Fm was evaluated by chlorophyll fluorescence measurements. The marked loss of PS2 activity in control thylakoids was evidently due to the loss of 33, 23, and 17 kDa extrinsic polypeptides and 28-25 kDa LHCP polypeptides. and K. Muthuchelian, M. Bertamini, N. Nedunchezhian.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public