Lichen thalli were exposed to 4 regimes differing in irradiance and duration of irradiation. Photosynthetic efficiency of thalli was monitored by chlorophyll fluorescence parameters and xanthophyll cycle analysis. Maximal quantum yield of photosystem 2 (FV/FM) decreased gradually with time in long-term treatment. The effect of additional short-term high irradiance (HI) treatment applied each 24 h was not significant. Nevertheless, short-term HI applied repeatedly on thalli kept in the dark led to a significant decrease of FV/FM. Non-photochemical quenching recorded during the long-term treatment corresponded to the content of zeaxanthin (Z). In short-term treatment, however, proportion of Z (and antheraxanthin) to total amount of xanthophyll cycle pigments recovered to the initial values every 24 h after each repeated short-term HI event in thalli kept in dark. Thus duration of irradiation rather than irradiance and frequency of HI events is important for a decrease in primary photosynthetic processes in wet thalli of Lasallia pustulata. Rapidly responding photoprotective mechanisms, such as conversion of xanthophyll cycle pigments, are involved mainly in short-term irradiation events, even at HI. and M. Barták ... [et al.].
This study presents for the first time in detail two manuscripts dealing with the beginnings of the Unitas Fratrum which are in the holdings of the Benedictine Library in Seitenstetten in Austria. Manuscript 72, dating from the beginning of the nineties of the 15th century, contains Latin translations of five letters written by the Czech Brethren to Jan Rokycana from 1489, which have been unknown till now and excerpts from five introductory chapters of the Síť víry (The Net of Faith) by Petr Chelčický, also translated into Latin in 1477. Manuscript 302 contains a copy of the record of an interrogation of four prominent Brethren in Kłodzko in 1480. This article indicates the possibilities of studying these texts, focusing on three main points: on their possible contribution to text tradition research, on research of the circumstances of the origin of their translations, and on the person of the scribe who made the collection. From the possible persons the inquisitor Jindřich Institoris has been excluded as his autograph doesn´t correspond with the writing of the scribe being looked for.
This study presents for the first time in detail two manuscripts dealing with the beginnings of the Unitas Fratrum which are in the holdings of the Benedictine Library in Seitenstetten in Austria. Manuscript 72, dating from the beginning of the nineties of the 15th century, contains Latin translations of five letters written by the Czech Brethren to Jan Rokycana from 1489, which have been unknown till now and excerpts from five introductory chapters of the Síť víry (The Net of Faith) by Petr Chelčický, also translated into Latin in 1477. Manuscript 302 contains a copy of the record of an interrogation of four prominent Brethren in Kłodzko in 1480. This article indicates the possibilities of studying these texts, focusing on three main points: on their possible contribution to text tradition research, on research of the circumstances of the origin of their translations, and on the person of the scribe who made the collection. From the possible persons the inquisitor Jindřich Institoris has been excluded as his autograph doesn´t correspond with the writing of the scribe being looked for.
This study presents for the first time in detail two manuscripts dealing with the beginnings of the Unitas Fratrum which are in the holdings of the Benedictine Library in Seitenstetten in Austria. Manuscript 72, dating from the beginning of the nineties of the 15th century, contains Latin translations of five letters written by the Czech Brethren to Jan Rokycana from 1489, which have been unknown till now and excerpts from five introductory chapters of the Síť víry (The Net of Faith) by Petr Chelčický, also translated into Latin in 1477. Manuscript 302 contains a copy of the record of an interrogation of four prominent Brethren in Kłodzko in 1480. This article indicates the possibilities of studying these texts, focusing on three main points: on their possible contribution to text tradition research, on research of the circumstances of the origin of their translations, and on the person of the scribe who made the collection. From the possible persons the inquisitor Jindřich Institoris has been excluded as his autograph doesn´t correspond with the writing of the scribe being looked for.
Based on new experimental data of linear and nonlinear spectroscopic investigations of LHC2 complexes, both the energy transfer and energy relaxation of excitons were studied in the limiting cases of strong pigment-pigment and pigment-protein interactions, respectively. Consequences of the structural basis and the dominance of strong pigment-pigment interactions in monomers were independently established by different optical measurements. In this model, the energy relaxation of excitons was determined by dynamical processes of exciton interactions with the radiation fíeld and the long-wave protein vibrations, respectively, in particular with the mode having the wave number of 43 cm'f
Dynamic changes of neoxanthin (NEO), violaxanthin (VIO), anteraxanthin (ANT), zeaxanthin (ZEA), chlorophyll (Chl) a, Chl b, α-carotene, β-carotene, and their behaviour under increasing duration of high irradiance (HI) were investigated in the soybean hypocotyl callus culture. The calli were induced on solid (1.1 % agar) MS medium (pH 5.8) supplemented with 4.52 μM 2,4-D, 2.32 μM kinetin, and 3 % sucrose. After 30 d of culture, the green calli were irradiated with "white light" (133W m-2) for 0, 3.5, and 24 h. HPLC profiles were separated on a C18 column. With increasing duration of HI, the content of total carotenoids (Cars) increased, but the ratio of Chl a+b/Cars decreased. With lengthening the duration of HI, there was induction of ZEA. Contents of ANT, α-carotene, and β-carotene remained nearly constant, but ratio of ZEA/Chl a+b increased with lengthening the HI duration. and D. M. Pandey, K. H. Kim, U. D. Yeo.
Both the biochemical and functional modifications of photosynthetic apparatus were observed during whole plant ontogeny. Net photosynthetic rate (Pn)» contents of photosystem (PS) 2 reaction centres, cytochromes 6559, and/ rates of electron- transport, cyclic and noncyclic photophosphorylation increased up till generative organs formation: a gradual decline followed as a result of senescence. The drop in activity of the electron-transport chain during senescence lead to the decline in content of PS2 reaction centres and Pn
Efficient degradation of damaged D1 during the repair of PSII is carried out by a set of dedicated FtsH proteases in the thylakoid membrane. Here we investigated whether the evolution of FtsH could hold clues to the origin of oxygenic photosynthesis. A phylogenetic analysis of over 6000 FtsH protease sequences revealed that there are three major groups of FtsH proteases originating from gene duplication events in the last common ancestor of bacteria, and that the FtsH proteases involved in PSII repair form a distinct clade branching out before the divergence of FtsH proteases found in all groups of anoxygenic phototrophic bacteria. Furthermore, we showed that the phylogenetic tree of FtsH proteases in phototrophic bacteria is similar to that for Type I and Type II reaction centre proteins. We conclude that the phylogeny of FtsH proteases is consistent with an early origin of photosynthetic water oxidation chemistry., S. Shao, T. Cardona, P. J. Nixon., and Obsahuje bibliografické odkazy
In the xantha1 (xan1) mutant of sunflower (Helianthus annuus L.), the effects on organ anatomy and seedling growth did correlate to the alteration of chloroplast biogenesis. The xan1 seedlings grown under 165 µmol(photon) m-2 s-1 revealed a severely altered chloroplast ultrastructure in cotyledons and leaves. Cross-sections or clarified tissues of the xan1 cotyledons did not show evident alterations with respect to normal cotyledons suggesting that the impairment of chloroplast biogenesis has negligible consequences on embryonic leaves. By contrast, the analysis of xan1 leaves showed that the defects in chloroplast biogenesis were correlated to a drastic reduction of organ size and to a clear enhancement of the trichome growth. The differentiation of palisade and spongy parenchyma in cotyledons and leaves of the xan1 mutant was normal but both organs displayed a drastic reduction in the plastid number with respect to wild type. In addition, xan1 hypocotyls showed a reduced development of the main vascular bundles in comparison with normal seedlings and an undersized central cylinder of the primary root. The exogenous supply of sucrose was not sufficient to revert in vitro the deficit of xan1 growth and the constraints in morphogenetic processes. and M. Fambrini ... [et al.].