Twelve-day-old barley seedlings were supplied with 23 μM methyl jasmonate (MeJA) or 10 μM paraquat (Pq) via the transpiration stream and kept in the dark for 24 h. Then they were exposed to 100 μmol m-2 s-1 PAR and samples were taken 1, 2, 3, and 6 h after irradiation. Treatment of seedlings with MeJA alone resulted in decreased content of chlorophyll (Chl), and net photosynthetic (PN) and transpiration rates. Pq treatment led to a decrease in Chl content and to a very strong inhibition of PN, the effects were manifested by 1 h of irradiation. Pq treatment did not affect the activity of ribulose-1,5 bisphosphate carboxylase (RuBPC, EC 4.1.1.39) but increased the activity of the photorespiratory enzymes phosphoglycolate phosphatase (PGP, EC 3.1.3.18), glycolate oxidase (GO, EC 1.1.3.1), and catalase (EC 1.11.1.6). Pre-treatment of seedlings with MeJA before exposure to Pq fully blocked the inhibitory effect of Pq on photosynthesis and protected against subsequent Pq-induced oxidative damage. and V. A. Hristova, L. P. Popova.
The photosynthesis and related plant productivity aspects of plants and cyanobacteria depend upon the functioning of photosystem 2 (PS2), associated with D1 and D2 heterodimer reaction centre core proteins. The D1 protein is encoded by psbA gene, genetically localized on the plastid genome (cpDNA), contains functional cofactors of PS2 in association with D2 protein, and also functions for radiant energy transformation through oxidation of water and reduction of plastoquinone. Surprisingly, D1 protein accounts for even less than 1% of the total thylakoid membrane protein content. In spite of that, its rate of turnover is very much comparable to ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) large subunit, most abundantly present in green tissue. The normal functioning of PS2 possesses damage-repair cycles of D1 protein. Generally, rate of photodamage does not exceed the rate of repair under optimal growth conditions, therefore, no adverse effect on photosynthetic efficiency is manifest. However, under strong irradiance coupled with elevated temperature, level of photodamage exceeds the rate of repair, resulting in photoinhibition, photodegradation of D1 protein, and lowering photosynthetic efficiency linked with plant productivity eventually. The features of D1 turnover process are reviewed, particularly with respect to molecular mechanisms.
This paper analyses two lists of errors in the Waldesian cult, as contained in manuscripts I F 230 (from 1399, and its twin manuscript Mil II 58), as well as I F 707 (from the early 15th century). The list in manuscript I F 230 was compiled earlier, whereas the one from manuscript I F 707 is identical with the list included in manuscript No. 229 from the library in Pelplin. The comparison of the anti-heretic lists of errors from manuscripts I F 230 and I F 707, as well as the analysis of their contents, reveals similarities and leads to a conclusion that they both refer to writings by inquisitor Petrus Zwicker, while the list in I F 230 could have been even authored by him.
The paper studies the typology of the initials following the way of construction of their corpus in the mutual ties in the development – departing from the late antique, considering the Byzantine and Pre-Romanesque and Romanesque types. The modifications of the initials are studied together with the changes of their function in the decoration system and in the cultural-historical context. The contribution also studies the changes of the terminology connected with the typology of the initials.
The paper is engaged with a definition of the typolotgy and modifications fo the caligraphic initials, compared with the typology of painted initials, and also with a comparative study of the terminoloty used in different languages for the specific compositions. The interest is also focused on relations among countries, regions and workshops that participated in the transformations of the caligrafic initials. The subject is studied on a broad period, from the Late Antiquity till the 16th century, but without a typology of fleuronée, only compositions of the body of the initials have been taken into consideration.
Incubation of maize NADP-malic enzyme with tetranitromethane (TNM) resulted in a total loss of enzyme activity. The loss of enzyme activity was not observed at pH 6.3 but at pH 8.0. NADP-malic enzyme was inactivated to almost 90 % by incubation with an 80-fold molar excess of TNM for 5 min at 30 °C. The substrate malate or Mg2+ alone gave no protection, while NADP provided considerable protection. NADP in the presence of malate and Mg2+ totally protected the enzyme activity, suggesting that tyrosine residue may be located at or near the active site of maize NADP-malic enzyme. The spectral analysis of the modified enzyme indicated that modification of at least one tyrosine residue per subunit resulted in complete loss of the enzyme activity. The fluorescence study of unmodified and modified enzymes postulated that essential tyrosine residue at maize NADP-malic enzyme is possibly involved in malate binding. and S. R. Rao, B. G. Kamath, A. S. Bhagwat.
This article is focused on opinions that the literary historian and Custodian of the Prague Imperial-Royal University Library (now the National Library of the Czech Republic) Josef Truhlář (1840-1914) had on Manuscripts of Dvůr Králové and Zelená Hora. Initially, he had been convinced of the authenticity of the Manuscripts, but after Gebauer´s groundbreaking article questioning their authenticity published in the Athenaeum journal in February 1886, he re-evaluated his older opinions and published a series of articles in this journal denying the authenticity of the Manuscripts. These articles were focused on suspicious finding circumstances of these allegedly old monuments, parallels in their texts with literary works from the early 19th century and on other contemporary forged manuscripts.
Influence of moderate chilling stress on vascular bundle sheath cell (BSC) and especially mesophyll cell (MC) chloroplasts of mature maize leaves was studied by electron microscopy and stereology. Plants of two inbred lines of maize, differing in their photosynthetic activity, and their F1 hybrids were cultivated during autumn in heated or unheated glasshouse. Generally, chilling temperatures resulted mainly in the decrease in stereological volume density (VD) of both granal and intergranal thylakoids of MC chloroplasts, while the ratio of granal to all thylakoids (granality) was less affected. The VD of peripheral reticulum and plastoglobuli usually increased after cold treatment of plants. The volume of MC chloroplasts usually increased under chilling stress, the shape of the chloroplasts changed only slightly. The ultra-structure of chloroplasts differed between individual genotypes; chilling-stressed hybrid plants showed positive heterosis particularly in the granal thylakoids' VD of MC chloroplasts. and J. Kutík ... [et al.].