In Evernia prunastri, photosynthetic gas exchange was saturated with yellow radiation (SOX) at 400 μmol m-2s-1, and then red (R), far-red (FR), or blue (B) radiations at irradiance of 15 μmol m-2s-1 were added. Because of photosynthesis saturation, any stimulation or decay in CO2 assimilation by any radiation quality could be attributed to the involvement of a non-photosynthetic photoreceptor. Thus CO2 assimilation, effective quantum yield, and photochemical quenching were enhanced when R was included, and decreased with FR. Blue radiation completely abolished CO2 fixation. Hence different spectral radiation qualities may activate non-photosynthetic photoreceptors such as phytochrome and blue photoreceptors, which are involved in regulating the photosynthetic activity in E. prunastri. and M. Segovia, F. L. Figueroa.
Effect of high temperature on the plastid gene expression during the light induced chloroplast development in etiolated seedlings was determined by Northern hybridisation using cloned DNA fragments of wheat chloroplast genome. Based on their response to high temperature, plastid genes were grouped into three categories: (1) plastid genes whose expression was not affected by high temperature (genes for rRNA, ribosomal proteins, tRNAs, and some genes coding for putative NADH dehydrogenase); (2) plastid genes whose expression increased at high temperature (genes coding for α-subunit of RNA polymerase and some unidentified transcripts, and (3) plastid genes whose expression decreased at high temperature (genes coding for proteins involved in photosynthetic process). Loss of a number of primary transcripts originating from operons consisting of genes that code for proteins involved in the photosynthetic process was observed. The expression of all the light inducible plastid genes was inhibited suggesting that the light inducibility property was lost at high temperature. and Abhay K. Singh, G. S. Singhal.
High CO2 concentrations (HC) in air induce partial deactivation of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO, EC 4.1.1.39). Under saturating irradiance, increase in [CO2] to 1 200 cm3 m-3 reduces the concentration of operating carboxylation centres by 20–30 %. At a further increase in [CO2], the activity remained on the same level. Under limiting irradiance, the lowest activity was reached at 600 cm3 (CO2) m-3. The presence of oxygen diminished deactivation, but O2 failed to stimulate reactivation under high CO2. Conditions that favour oxygenation of ribulose-1,5- bisphosphate (RuBP) facilitated reactivation. Even HC did not act as an inhibitor. HC induces deactivation of RuBPCO by increasing the concentration of free reaction centres devoid of the substrate, which are more vulnerable to inhibition than the centres filled with substrates or products. and J. Viil ... [et al.].
The article deals with two sermons by a Prague Dominican known as Iohannes Carmelita that were delivered at the Archdiocesan Synod in Prague in 1401 and 1404. Based on critical editions of both sermons, the article presents Carmelita’s preaching style and the authorities referred to by him and places them in the context of other extant Prague synodal sermons in the pre-Hussite period.