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Start Over Coverage 355-362

1. A fixed point method to compute solvents of matrix polynomials

Creator:
Marcos, Fernando and Pereira, Edgar
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
fixed point method, matrix polynomial, and matrix differential equation
Language:
English
Description:
Matrix polynomials play an important role in the theory of matrix differential equations. We develop a fixed point method to compute solutions of matrix polynomials equations, where the matricial elements of the matrix polynomial are considered separately as complex polynomials. Numerical examples illustrate the method presented.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2. Compensatory effects of elevated CO2 concentration on the inhibitory effects of high temperature and irradiance on photosynthetic gas exchange in carrots

Creator:
Thiagarajan, A., Lada, R., and Joy, P.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Daucus, stomatal conductance, transpiration rate, and water use efficiency
Language:
Multiple languages
Description:
We determined the interactive effects of irradiance, elevated CO2 concentration (EC), and temperature in carrot (Daucus carota var. sativus). Plants of the cv. Red Core Chantenay (RCC) were grown in a controlled environmental plant growth room and exposed to 3 levels of photosynthetically active radiation (PAR) (400, 800, 1 200 µmol m-2 s-1), 3 leaf chamber temperatures (15, 20, 30 °C), and 2 external CO2 concentrations (Ca), AC and EC (350 and 750 µmol mol-1, respectively). Rates of net photosynthesis (PN) and transpiration (E) and stomatal conductance (gs) were measured, along with water use efficiency (WUE) and ratio of internal and external CO2 concentrations (Ci/Ca). PN revealed an interactive effect between PAR and Ca. As PAR increased so did PN under both C a regimes. The gs showed no interactive effects between the three parameters but had singular effects of temperature and PAR. E was strongly influenced by the combination of PAR and temperature. WUE was interactively affected by all three parameters. Maximum WUE occurred at 15 °C and 1 200 µmol m-2 s-1 PAR under EC. The Ci /Ca was influenced independently by temperature and Ca. Hence photosynthetic responses are interactively affected by changes in irradiance, external CO2 concentration, and temperature. EC significantly compensates the inhibitory effects of high temperature and irradiance on PN and WUE. and A. Thiagarajan, R. Lada, P. Joy.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Expression, purification and preliminary crystallization study of RpaC protein from Synechocystis sp. PCC6803

Creator:
Cséfalvay, E., Lapkouski, M., and Komárek, O.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
affinity chromatography, photosystem, and phycobilisome - PSII supercomplex
Language:
Multiple languages
Description:
State transitions in cyanobacteria are physiological adaptation mechanisms that change the interaction of the phycobilisomes with the photosystem I and photosystem II core complexes. This mechanism is essential for cyanobacteria at low light intensities. Previous studies of cyanobacteria have identified a gene named rpaC, which appears to be specifically required for state transitions. The gene product of rpaC is very probably a transmembrane protein that is a structural component of the phycobilisome-photosystem II supercomplex. However, the physiological role of RpaC protein is unclear. Here we report the construction of an expression system that enables high production of fusion protein TrxHisTagSTag-RpaC, and describe suitable conditions for purification of this insoluble protein at a yield of 3 mg per 1 dm3 of bacterial culture. Cleavage with HRV 3C protease to remove the TrxHisTagSTag portion resulted in low yields of RpaC-protein (∼ 30 µg/dm3 of bacterial culture), therefore the applicability to structural studies was tested for the fusion protein only. Several preliminary conditions for crystallization of TrxHisTagSTag-RpaC were set up under which microcrystals were obtained. This set of conditions will be a good starting point for optimization in future crystallization experiments. TrxHisTagSTag-RpaC protein may prove useful in biochemical studies where the small size of RpaC protein is limiting the investigation of interactions with significantly larger parts of the photosynthetic apparatus. Furthermore, the purification procedure described here might also be applied to the production and purification of other small membrane proteins for biochemical and structural studies. and E. Cséfalvay, M. Lapkouski, O. Komárek.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public