Photosynthetic rates of green leaves (GL) and green flower petals (GFP) of the CAM plant Dendrobium cv. Burana Jade and their sensitivities to different growth irradiances were studied in shade-grown plants over a period of 4 weeks. Maximal photosynthetic O2 evolution rates and CAM acidities [dawn/dusk fluctuations in titratable acidity] were higher in leaves exposed to intermediate sunlight [a maximal photosynthetic photon flux density (PPFD) of 500-600 µmol m-2 s-1] than in leaves grown under full sunlight (a maximal PPFD of 1 000-1 200 µmol m-2 s-1) and shade (a maximal PPFD of 200-250 µmol m-2 s-1). However, these two parameters of GFP were highest in plants grown under the shade and lowest in full sun-grown plants. Both GL and GFP of plants exposed to full sunlight had lower predawn Fv/Fm [dark adapted ratio of variable to maximal fluorescence (the maximal photosystem 2 yield without actinic irradiation)] than those of shade-grown plants. When exposed to intermediate sunlight, however, there were no significant changes in predawn Fv/Fm in GL whereas a significant decrease in predawn Fv/Fm was found in GFP of the same plant. GFP exposed to full sunlight exhibited a greater decrease in predawn Fv/Fm compared to those exposed to intermediate sunlight. The patterns of changes in total chlorophyll (Chl) content of GL and GFP were similar to those of Fv/Fm. Although midday Fv/Fm fluctuated with prevailing irradiance, changes of midday Fv/Fm after exposure to different growth irradiances were similar to those of predawn Fv/Fm in both GL and GFP. The decreases in predawn and midday Fv/Fm were much more pronounced in GFP than in GL under full sunlight, indicating greater sensitivity in GFP to high irradiance (HI). In the laboratory, electron transport rate and photochemical and non-photochemical quenching of Chl fluorescence were also determined under different irradiances. All results indicated that GFP are more susceptible to HI than GL. Although the GFP of Dendrobium cv. Burana Jade require a lower amount of radiant energy for photosynthesis and this plant is usually grown in the shade, is not necessarily a shade plant. and J. He, L. C. D. Teo
In this article, related to a talk given at the International Meeting "Photosynthesis Research for Sustainability-2015", we honor Dr. George C. Papageorgiou, a highly respected scientist and an outstanding teacher and mentor. Praising him for these virtues, indispensable for research sustainability, we also bring to discussion aspects that undermine nowadays both education and research sustainability. We argue that these aspects are principally created by the predominant bureaucratic system, which, by favoring short-term utilitarian orientations and obeying "market laws", jeopardizes university freedom and autonomy, and has turned to "measuring" scientific "production" and establishing accordingly designed funding policies and hiring/firing/promotion criteria, which lead to merit-chasing, grant-hunting, changes in publication practice, and suppression of heterodox ideas. Such system impedes research, creates antagonism, and drives the potentially creative researcher away from originality and discovery, and from the unique satisfaction and benefit that these bring., M. Tsimilli-Michael, P. Haldimann., Název rubriky: Opinion paper, and Obsahuje bibliografii
Al3+ in combination with kinetin showed more protection against degradation of chlorophyll (Chl) and protein than Al3+ or kinetin alone during dark-induced senescence in wheat primary leaf segments. MV-dependent whole chain electron transport, photosystem (PS) 2 mediated oxygen evolution, and PS1 activities were also delayed to a greater extent. Absorbed excitation energy distribution was more in favour of PS1 in Al3+ plus kinetin-treated leaf thylakoids at 72 h. and D. Subhan, S. D. S. Murthy.
Metalloporphyrins serve important roles in biology and as components in emerging technological assemblies for energy conversion. In this report, we describe the synthesis and characterization of a novel cobalt(II) 5,10,15,20-tetrakis
(3-fluorophenyl)porphyrin bearing a 4-vinylphenyl surface attachment group at a beta position on the macrocycle. Electrochemical measurements show the 3-fluorophenyl groups at the meso positions of the porphyrin perturb the reduction potentials of the complex to more positive values as compared to
non-fluorinated analogs, thus allowing access to reduced cobalt porphyrin species at significantly less negative applied bias potentials. The complex, cobalt(II) 5,10,15,20-tetrakis(3-fluorophenyl)-2-(4-vinylphenyl)porphyrin, is abbreviated in this article as Gov-1 in honor of Govindjee for his pioneering investigations in the role of fluorine as a promoter of novel
protein-substrate interactions and the inspirational role he continues to have in encouraging young investigators in the areas of natural and artificial photosynthesis., D. Khusnutdinova, M. Flores, A. M. Beiler, G. F. Moore., and Obsahuje bibliografické odkazy
This article examines the evolution of the term tabula from antiquity onward and the use of it in middle ages and early modern age literature. It analyses in detail the term tabulae ecclesiae finding its triple meaning in the Central European environment: 1) tabulae written on parchment (later on paper) and fixed on a board in the church – these contained information and instructions for laymen, those in the sacristy or in the choir contained normative constitutions or doctrinal auctoritates for clerics, 2) tabulae on the church walls near the high-altar contained lists of persons to be remembered in liturgy permanently; their external form were frescos framing their names like funeral tablets, 3) the same term tabulae ecclesiae is used also in the sense of financial cash resulting from a church collection. In all cases the ideological connection of medieval church boards to antique legistic texts (1.), to fasti (2.) or to the external form of a real board only (3.) is examined.