Irradiation of thylakoid membranes at 40 °C resulted in complete inhibition of photosystem (PS) 2 activity measured as 2,6-dichlorophenol indophenol (DCIP) photoreduction either in the absence or presence of 1,5-diphenylcarbazide (DPC). Concomitant with the inactivation of PS2 activity, several thylakoid proteins were lost and high molecular mass cross-linking products appeared that cross-reacted with antibodies against proteins of PS2 but not with antibodies against proteins of other three complexes PS1, ATP synthase, and cytochrome b6f. Irradiation of thylakoid membranes suspended in buffer of basic pH or high concentration of Tris at 25 °C resulted in the formation of cross-linking products similar to those in thylakoid membranes irradiated at 40 °C. Presence of radical scavengers and DPC during the high temperature treatment prevented the formation of cross-linking products. These results suggest the involvement of oxygen evolving co mplex (OEC) in the formation of cross-linking between PS2 proteins in thylakoid membrane irradiated at high temperature. and Abhay K. Singh, G. S. Singhal.
Accumulation of glycollate or glyoxylate on irradiation of leaf discs in the presence of a-hydroxypyridinemethane sulfonate (a-HPMS) oř glycidate, respectively, was studied in C3-C4 intermediates of Altemanthera species (A. ficoides, A. tenellá) and Paríhenium hysíerophorus in comparison with the partem in C3 or C4 species. The levels of these two photorespiratory metabolites were reduced in the intermediates (< 75 % of that in C3) while being very low in the C4 species (about 10 % of that in C3). The inhibitory effect of bicarbonate on the glycollate or glyoxylate accumulation was pronounced in the C3 species (60 % inhibition), moderate in the intermediates (about 45 %), and very low (< 2 %) in the C4 plants. The negligible effect of bicarbonate on these photorespiratory metabolites in the C4 species is expected to be due to their C4 acid-based C02-concentrating mechanism. In the presence of 5 mM bicarbonate, the levels of glycollate and glyoxylate in the C3 species were similar to those in the C3-C4 intermediates. We speculate that a high intemal CO2 pool, possibly due to an efficient CO2 recycling/refixation mechanism, may be an additional reason besides the partial reduction in photorespiratory enžymic capacity for reduced levels of photorespiratory glycollate/glyoxylate in C3-C4 intermediates.Accumulation of glycollate or glyoxylate on irradiation of leaf discs in the presence of a-hydroxypyridinemethane sulfonate (a-HPMS) oř glycidate, respectively, was studied in C3-C4 intermediates of Altemanthera species (A. ficoides, A. tenellá) and Paríhenium hysíerophorus in comparison with the partem in C3 or C4 species. The levels of these two photorespiratory metabolites were reduced in the intermediates (< 75 % of that in C3) while being very low in the C4 species (about 10 % of that in C3). The inhibitory effect of bicarbonate on the glycollate or glyoxylate accumulation was pronounced in the C3 species (60 % inhibition), moderate in the intermediates (about 45 %), and very low (< 2 %) in the C4 plants. The negligible effect of bicarbonate on these photorespiratory metabolites in the C4 species is expected to be due to their C4 acid-based C02-concentrating mechanism. In the presence of 5 mM bicarbonate, the levels of glycollate and glyoxylate in the C3 species were similar to those in the C3-C4 intermediates. We speculate that a high intemal CO2 pool, possibly due to an efficient CO2 recycling/refixation mechanism, may be an additional reason besides the partial reduction in photorespiratory enžymic capacity for reduced levels of photorespiratory glycollate/glyoxylate in C3-C4 intermediates.
The article is devoted to František Čáda. The author describes Čáda´s life dedicated to archivistic, teaching, research and editorial work. She describes ow the changes of the political regime in 1948 affected the life of this outstanding Czech legal historian, a diligent editor and and excellent teacher who was forced to leave the university. Only thanks to their commitment and assistance prof. Vojtíšek later found application in manuscirpts research. Diligent and accurate work brought him recognition not only among law historians even among codicologists. and Medailonek