The responses to root oxygen deficiency conceming the photosynthesis, saccharide contents and minerál uptake háve been investigated in Carex species, which were different in their anoxia-tolerance. The net rate of photosynthesis (Fn) anoxia- sensitive C. extensa was not affected by root anaerobiosis. Despite short-term effects of root anaerobiosis on values in the anoxia-tolerant species C. remota and C. pseudocyperus, root oxygen supply did not influence P^, when the plants were allowed to acclimate. The saccharide contents of the anoxia-tolerant species were almost not affected by prolonged anaerobiosis. 40 days of root oxygen deficiency led to significant changes in the shoot saccharide composition of C. extensa: contents of glucose and fructose were increased 4-fold and sucrose content was significantly decreased. In the roots no sucrose could be detected, but the starch content was increased, and the glucose and fructose contents did not change when compared with aerobic conditions. Under anaerobic conditions, minerál uptake of the anoxia- sensitive species decreased by 50 %, while the minerál uptake of the anoxia-tolerant species was significantly increased or did not change at all, in comparison with the aerobic conditions. The growth reduction of C. extensa under anaerobic conditions was therefore primarily due to inability to také up an adequate amount of nutrients.
The vault in Vladislav Hall is a structural masterpiece of great historical value. Its structural analysis revealed that the permanent load exerted by its self weight is uniformly transmitted into the vaults and ribs without any potential crack appearance. The topical issue, however, is its response to temperature changes with respect to actual effects. Computations show that temperature changes may cause problems., Petr Fajman, Jiří Máca and Pavel Beran., and Obsahuje bibliografii
The steady-state oxygen evolution rate was previously shown to be stimulated by the disaccharide trehalose in PSII suspension. Here we showed a similar increase in the rate of oxygen evolution in PSII core complexes from spinach in solution and in proteoliposomes in the presence of trehalose. Using direct electrometrical technique, we also revealed that trehalose had no effect on the kinetics of electron transfer from Mn to redox-active-tyrosyl radical, YZ (S1 - S2 transition), while it accelerated the kinetics of electrogenic proton transport during S2 - S3 and S4 - S0 transitions of the wateroxidizing complex (WOC) induced by the first, second, and third laser flashes in dark-adapted PSII samples. These observations imply that the effect of trehalose occurrs due to its interaction with the WOC., M. D. Mamedov, E. S. Nosikova, L. A. Vitukhnovskaya, A. A. Zaspa, A. Yu. Semenov., and Obsahuje bibliografické odkazy
Urban gardens can harbour a high diversity of insects, which are critically important components of urban ecosystems. In this work, we investigate the richness and diversity of a major taxon of economic and ecological importance, the aphids (Hemiptera: Aphididae), and their main insect predators, the hoverflies (Diptera: Syrphidae) and ladybirds (Coleoptera: Coccinellidae), in urban gardens. We examined how variation in environmental factors associated with urbanisation (garden host plant abundance, garden plant richness, garden size, proportion of impervious surfaces in the surrounding area) directly and indirectly (via prey and predator abundance) influence the local diversity and abundance of aphids, ladybirds, and hoverflies. Sixty-seven domestic gardens located in southern England were surveyed during the peak period of aphid abundance, and the numbers and identity of aphids and their predators were recorded. We observed 45 aphid species (179917 individuals in total), 15 hoverfly species (494 individuals) and 8 ladybird species (173 individuals). We found that aphid species richness and abundance were positively associated with utilised host plant abundance and garden plant species richness. Hoverfly abundance was positively correlated with garden plant richness. The abundance of ladybirds was positively correlated with aphid abundance and garden plant species richness, and negatively associated to the proportion of impervious surfaces in the surrounding environment. The difference in responses between the two major taxa of aphid predators may reflect differences in their behaviour and natural history. Our results indicate that overall increases in urban land cover are not favourable for ladybirds as a group, and that fine scale habitat variables that are determined by garden owners have the potential to greatly affect the diversity of aphids and their primary predators., Elise A. Rocha, Estevão N.F. Souza, Lewis A.D. Bleakley, Christopher Burley, Jade L. Mott, Gloria Rue-Glutting, Mark D.E. Fellowes., and Obsahuje bibliografii