University of Konstanz

About: University of Konstanz is a education organization based out in Konstanz, Baden-Württemberg, Germany. It is known for research contribution in the topics: Population & Visualization. The organization has 12115 authors who have published 27401 publications receiving 951162 citations. The organization is also known as: University of Constance & Universität Konstanz.

Cellular compartmentation of nickel in the hyperaccumulators Alyssum lesbiacum, Alyssum bertolonii and Thlaspi goesingense

Abstract: Nickel uptake and cellular compartmentation were investigated in three Ni hyperaccumulators: Alyssum bertolonii (Desv), Alyssum lesbiacum (Candargy) and Thlaspi goesingense (Hal acsy). The three species showed similar hyperaccumulation of Ni, but T. goesingense was less tolerant to Ni than the two Alyssum species. An addition of 500 mg Ni kg � 1 to a nutrient-rich growth medium significantly increased shoot biomass of all three species, suggesting that the Ni hyperaccumulators have a higher requirement for Ni than normal plants. Energy-dispersive X-ray microanalysis (EDXA) was performed on frozen- hydrated tissues of leaves (all species) and stems ( Alyssum only). In all species analysed, Ni was dis- tributed preferentially in the epidermal cells, most likely in the vacuoles, of the leaves and stems. In stems, there was a second peak of Ni in the bound- ary cells between the cortical parenchyma and the vascular cylinder. The non-glandular trichomes on the leaf surfaces of the two Alyssum species were highly enriched with Ca, but contained little Ni except in the base. In the leaves of T. goesingense, the large elongated epidermal cells contained more Ni than the cells of the stomatal complexes. The role of cel- lular compartmentation in Ni hyperaccumulation is discussed.

Cadmium toxicity in plants.

Abstract: Cadmium is an important pollutant in the environment, toxic to most organisms and a potential threat to human health: Crops and other plants take up Cd from the soil or water and may enrich it in their roots and shoots. In this review, we summarize natural and anthropogenic reasons for the occurrence of Cd toxicity, and evaluate the observed phytotoxic effects of plants growing in Cd-supplemented soil or nutrient solution. Cd-induced effects include oxidative stress, genotoxicity, inhibition of the photosynthetic apparatus, and inhibition of root metabolism. We explain proposed and possible interactions between these modes of toxicity. While discussing recent and older studies, we further emphasize the environmental relevance of the experiments and the physiological response of the plant.

Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs.

Abstract: Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote-eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. Both genomes have >21,000 protein genes and are intron rich, and B. natans exhibits unprecedented alternative splicing for a single-celled organism. Phylogenomic analyses and subcellular targeting predictions reveal extensive genetic and biochemical mosaicism, with both host- and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosymbiont cytosol of both algae. Mitochondrion-to-nucleus gene transfer still occurs in both organisms but plastid-to-nucleus and nucleomorph-to-nucleus transfers do not, which explains why a small residue of essential genes remains locked in each nucleomorph.

Follower Behavior and Organizational Performance : the Impact of Transformational Leaders

Abstract: This study sheds light on the mediating processes by which transformational leadership influences follower performance and innovation, respectively. We hypothesize that transformational leaders boost follower performance by stimulating organizational citizenship behavior, whereas they enhance follower innovation by triggering controversial discussion of task related issues (debate). On the contrary, we do not expect these mediating effects to hold for the relationship between transactional leadership and follower performance and innovation, respectively. Our hypotheses were confirmed in an empirical study of N = 91 leaders from 91 German companies. Conclusions for leadership research are drawn. Key words: debate, innovation, organizational citizenship behavior, transactional leadership, transformational leadership

Growth phase-regulated expression of bolA and morphology of stationary-phase Escherichia coli cells are controlled by the novel sigma factor sigma S.

Abstract: The novel sigma factor (sigma S) encoded by rpoS (katF) is required for induction of many growth phase-regulated genes and expression of a variety of stationary-phase phenotypes in Escherichia coli. Here we demonstrate that wild-type cells exhibit spherical morphology in stationary phase, whereas rpoS mutant cells remain rod shaped and are generally larger. Size reduction of E. coli cells along the growth curve is a continuous and at least biphasic process, the second phase of which is absent in rpoS-deficient cells and correlates with induction of the morphogene bolA in wild-type cells. Stationary-phase induction of bolA is dependent on sigma S. The "gearbox" a characteristic sequence motif present in the sigma S-dependent growth phase- and growth rate-regulated bolAp1 promoter, is not recognized by sigma S, since stationary-phase induction of the mcbA promoter, which also contains a gearbox, does not require sigma S, and other sigma S-controlled promoters do not contain gearboxes. However, good homology to the potential -35 and -10 consensus sequences for sigma S regulation is found in the bolAp1 promoter.