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Start Over Coverage 35-39

4. Photosystem 2 photochemistry and pigment composition of a yellow mutant of rice (Oryza sativa L.) under different irradiances

Creator:
Chen, Q., Wang, L. F., Su, N., Qin, H. D., Niu, H. B., Wang, J. L., Zhai, H. Q., and Wan, J. M.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
β-carotene, chlorophyll, photochemical and non-photochemical quenching, and xanthophyll cycle
Language:
Multiple languages
Description:
A yellow leaf colouration mutant (named ycm) generated from rice T-DNA insertion lines was identified with less grana lamellae and low thylakoid membrane protein contents. At weak irradiance [50 µmol(photon) m-2 s-1], chlorophyll (Chl) contents of ycm were ≈20 % of those of WT and Chl a/b ratios were 3-fold that of wild type (WT). The leaf of ycm showed lower values in the actual photosystem 2 (PS2) efficiency (ΦPS2), photochemical quenching (qP), and the efficiency of excitation capture by open PS2 centres 1 (Fv'/Fm') than those of WT, except no difference in the maximal efficiency of PS2 photochemistry (Fv/Fm). With progress in irradiance [100 and 200 µmol(photon) m-2 s-1], there was a change in the photosynthetic pigment stoichiometry. In ycm, the increase of total Chl contents and the decrease in Chl a/b ratio were observed. ΦPS2, qP, and Fv'/Fm' of ycm increased gradually along with the increase of irradiance but still much less than in WT. The increase of xanthophyll ratio [(Z+A)/(V+A+Z)] associated with non-photochemical quenching (qN) was found in ycm which suggested that ycm dissipated excess energy through the turnover of xanthophylls. No significant differences in pigment composition were observed in WT under various irradiances, except Chl a/b ratio that gradually decreased. Hence the ycm mutant developed much more tardily than WT, which was caused by low photon energy utilization independent of irradiance. and Q. Chen ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

6. The influence of leaf windows on the utilization and absorption of radiant energy in seven desert succulents

Creator:
Egbert, K. J. and Martin, C. E.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, Haworthia truncata, Lithops olivacea, Opthalmophyllum longum, Peperomia dolabriformis, Peperomia graveolens, Peperomia pulchella, photoinhibition, photosynthesis, and Senecio rowleyanus
Language:
Multiple languages
Description:
Four fluorescence parameters [Fv/Fm = the intrinsic efficiency of energy conversion via photosystem 2 (PS2); Fv'/Fm'= the efficiency of energy conversion via PS2 in the light; P = fraction of absorbed radiant energy utilized for photosynthesis; and D = fraction of absorbed radiant energy dissipated as heat] were measured on leaves of seven species of succulents having epidermal windows. While the function of leaf windows has reportedly been to increase absorption of radiant energy and, hence, the rate of photosynthesis in these species, recent evidence indicates that this translucent portion of epidermal tissue, lacking chlorophyll, may also result in photoinhibition in these species, especially for those with growth habits aboveground. Species with aboveground and belowground growth habits were compared with their leaf windows covered with reflective tape and with windows unobstructed. Results showed no increase in photoinhibition for these species resulting from the radiant energy penetrating the window tissue. Although the efficiency of the photosynthetic mechanism was not significantly influenced by the additional radiant energy provided by the window for individual species, there were significant differences in the efficiencies of radiant energy capture (Fv'/Fm') and utilization (P) between the two growth habits. Species with an aboveground growth habit were less efficient in radiant energy utilization compared with the species having a belowground growth habit. and K. J. Egbert, C. E. Martin.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

7. Uplatnění polarografie ve fyzikálněchemickém výzkumu

Creator:
Pospíšil, Lubomír
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
Heyrovský, Jaroslav, 1890-1967, 20. století, polarografie, fyzici, chemici, physicists, chemists, Česko, Czechia, čeští fyzici, čeští chemici, 10, and 544
Language:
Czech and English
Description:
Polarografická metoda umožňuje studium řady fyzikálněchemických problémů. Jsou uvedeny příklady z oblasti výzkumu struktury fázového rozhraní elektroda/roztok, adsorpce na povrchu elektrody, elektrochemického fotoefektu, fázových přechodů povrchových filmů, přenosu elektronu na molekulární vzdálenosti a oscilačních elektrochemických systémů., Polarography is a suitable method for solving numerous problems of physical chemistry. Examples from the following fields are given: structure of electrode/solution interfaces, adsorption on electrode surface, electrochemical photo-effect, phase transition of surface films, electron transfer over molecular distances, and electrochemical oscillating systems., Lubomír Pospíšil., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public