Field measurements of gas exchange were made using a portable infra-red gas analyser on six species of early-successional woody plants in Singapore. Macaranga heynei, Mallotus paniculatus and Trema tomentosa grow on relatively fertile soils. Adinandra dumosa, Uillenia suffruticosa and Melostoma malabalhricum are species typical of extremely acidic and infertile soils. The six species were similar in their photosynthetic responses to irradiance when net photosynthetic rate (P^) was expressed on a leaf area basis. However, when PN was converted to a rate per unit leaf dry mass, the fertile soil species showed higher rates of dark respiration and photosynthesis. No difference in water use efficiency between the two sets of species was found.
The effects of a high temperature on leaf photosynthetic response of Lupinus albus, a species native from the Mediterranean zone, were studied under varying tissue water status and irradiance (/). At leaf temperatures optimal (25 °C) or near-optimal (15 ®C) for carbon assimilation in lupins, photosynthetic capacity (P^) was decreased at leď relative water content (RWC) around 60 %. The temperature above the optimum (e g. 35 oC) decreased at high RWC (80 %). Irrespective of the leaf water status the optimum leaf temperature for in lupins was around 25 "C. The inhibition of P^ by lupin leaf discs at 35 °C was greatly enhanced at high I. Leaf disc treatment at 35 in the dark did not change quantum yield or Pn. When in addition to 35 the leaves were subjected to high I (TS + IS) or to high I and dehydration (TS + IS + WS), then a substantial decrease was observed in the quantum yield (66 and 77 % of the values in Controls, respectively) and in (31 and 56 %, respectively).
Effects of excess Cd and Cu on the contents of total glutathione and phytochelatin (PC) were measured in roots and leaves of intact spinách piants. The total glutathione levels declined with the PCs synthesis. The kinetic data indicated that the shorter PCs were substrates for the longer PCs. PCs appear much earlier in roots than in leaves of intact spinách piants. The PC formation was stimulated most effectively by Cd, less so by Cu.
It is argued in the article that the peaceful transition to capitalism in communist countries was not possible without the co-action of the nomenklatura, whose interest was to transform their informal access to state-owned capital into an authentic 'grand entrepreneurship'. The necessary acquisition of physical cap ital was achieved by means of mass privatisation schemes in which the nomenklatura took advantage of their social capital and information asymmetries. In the Czech case, there were three social groups competing for a position among the new entrepreneurial elite. The initially large gains of the nomenklatura gradually eroded when new businesses opened to domestic and international competition, where competitiveness depended on endowments of human (entrepreneurial) and economic capital. In the subsequent wave of ownership restructuring, initiated after 1994, the former nomenklatura was partially squeezed out of the tradable sector, which was occupied by better skilled foreign and domestic entrepreneurs. The exiting entrepreneurs converted their holdings into consumer goods, or defected to sectors less open to competition, where the alignment of social capital and bureaucracy persisted. Their position depends now on the pending reforms of public administration and the search for a more efficient social model.
Photosystem 2 (PS 2) reaction centre can be considered as a water-plastoqninone oxido-reductase. Using four photons it transfers four electrons from two molecules of water to plastoquinone (PQ), producing the molecular oxygen and two molecules of double reduced PQ. PS 2 is the site of the antagonistic action of bicarbonate and formáte on PS 2 electron flow; incubation of isolated chloroplasts with formáte results in full inhibition of electron flow actívity, which can be restored by addition of bicarbonate. This bicarbonate effect is located at the Dl protein and affects the electron flow between the primary quinone and the PQ pool. Bicarbonate is probably involved in stabilizatíon of tíie semireduced secondary quinone Qb, and in the protonation reactions at this site. Under physiological conditions bicarbonate is boimd to thylakoid membranes. Addition of formáte to thylakoids appears to release CO2. The bicarbonate effect is not only observed in isolated chloroplasts, but also in intact organisms as green algae and leaves. Bicarbonate Controls PS 2 electron flow in order to cope with stress conditions leading to, for instance, photoinhibition or to the high rates of photorespiration.