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59. Heterologous expression of a ketohexokinase in potato plants leads to inhibited rates of photosynthesis, severe growth retardation and abnormal leaf development

Author

Geigenberger, P., Regierer, B., Lytovchenko, A., Leisse, A., Schauer, N., Springer, F., Kossmann, J., Fernie, A.R., Geigenberger, P., Regierer, B., Lytovchenko, A., Leisse, A., Schauer, N., Springer, F., Kossmann, J., and Fernie, A.R.

Abstract

In the present paper we investigated the effect of heterologous expression of a rat liver ketohexokinase in potato (Solanum tuberosum L.) plants with the aim of investigating the role of fructose 1-phosphate in plant metabolism. Plants were generated that contained appreciable activity of ketohexokinase but did not accumulate fructose 1-phosphate. They were, however, characterised by a severe growth retardation and abnormal leaf development. Studies of (14)CO(2) assimilation and metabolism, and of the levels of photosynthetic pigments, revealed that these lines exhibited restricted photosynthesis. Despite this fact, the levels of starch and soluble sugars remained relatively constant. Analysis of intermediates of starch and sucrose biosynthesis revealed large increases in the triose phosphate and fructose 1,6-bisphosphate pools but relatively unaltered levels of inorganic phosphate and 3-phosphoglycerate, and these lines were also characterised by an accumulation of glyceraldehyde. The transformants neither displayed consistent changes in the activities of Calvin cycle enzymes nor in enzymes of sucrose synthesis but displayed a metabolic profile partially reminiscent of that brought about by end-product limitation, but most likely caused by an inhibition of photosynthesis brought about by the accumulation of glyceraldehyde. Analysis of the metabolite contents in lamina and vein fractions of the leaf, and of the enzymes of carbohydrate oxidation indicate that the phloem-enriched veins of ketohexokinase-expressing leaves tend toward hypoxia and indicate a problem of phloem transport.

Published
2004

68. Magnetic hedgehog-like nanostructures

Author

Brombacher, C., primary, Falke, M., additional, Springer, F., additional, Rohrmann, H., additional, Goncharov, A., additional, Schrefl, T., additional, Bleloch, A., additional, and Albrecht, M., additional

Published
2010
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92. Removal of SiO2 nanoparticles from industry wastewaters and subsurface waters by ultrafiltration: Investigation of process efficiency, deposit properties and fouling mechanism

Author

Springer, F., Laborie, S., and Guigui, C.

Subjects
*SILICA nanoparticles, *INDUSTRIAL waste purification, *ULTRAFILTRATION, *FOULING, *WATER purification, *CELLULOSE, *ARTIFICIAL membranes
Abstract

Abstract: The novel properties of nanomaterials offer great promise of new technological breakthroughs. Consequently, their use in industry is expanding, and with it the risk of their being released in industrial effluents, and later in surface waters. This raises the problem of potential environmental hazards that are as yet unknown. The work presented in this paper evaluates the feasibility of membrane ultrafiltration for the removal of SiO2 nanoparticles (78nm mean hydrodynamic diameter) in suspension at 0.14wt% with the objective of treating them as pollutant compounds in industrial effluents. Regenerated cellulose membranes with two MWCOs of 10 and 100kDa were implemented. The influence of the membrane MWCO, the TMP and the stirring rate during filtration were examined. Stirred filtrations were performed at increasing TMP so as to characterise flux behaviour and retention rates. The feasibility of membrane ultrafiltration for this application was proved since the results of the 10kDa membrane showed the highest expectable retention rates (>99.6%) given the analytical methods used, and steady permeability results [30–40Lh−1 m−2 bar−1] independently of TMP and filtration course. Moreover, performance was shown to be sustainable as fouling was mostly reversible (>90%), being removable by simple membrane surface rinsing with ultrapure water. This was confirmed by the reconstruction of fouling mechanisms for both membranes. Unstirred and constant TMP 40, 80 and 200kPa filtration experiments were run to study fouling phenomena and the filtration cake characteristics (compressibility and porosity). Two distinct fouling mechanisms were highlighted: the 100kDa membrane underwent internal and sometimes irreversible fouling in the form of pore clogging before cake filtration, while the 10kDa membrane was characterised by filtration cake only. This work proposes solutions for the predicament of nanoparticle release into the environment and opens up perspectives for efficient wastewater treatment in the context of their industrial development. [Copyright &y& Elsevier]

Published
2013
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96. Assessment of relevant hepatic steatosis in obese adolescents by rapid fat-selective GRE imaging with spatial-spectral excitation: a quantitative comparison with spectroscopic findings.

Author

Springer F, Ehehalt S, Sommer J, Ballweg V, Machann J, Binder G, Claussen CD, Schick F, DISKUS-Study Group, Springer, Fabian, Ehehalt, Stefan, Sommer, Julia, Ballweg, Verena, Machann, Jürgen, Binder, Gerhard, Claussen, Claus D, and Schick, Fritz

Abstract

Objective: To test the feasibility of fat-selective GRE imaging using a spectral-spatial excitation technique for determination of intrahepatic lipid content (IHL) in obese adolescents.Methods: Fat-selective MR imaging (1.5 T) was applied to record a single axial slice through a representative liver region within a single breath-hold. The sequence uses six equidistant slice-selective excitation pulses with binomial amplitude ratios to achieve high selectivity for lipid signals after appropriate shimming. IHL(MRI) content was quantified using signal intensity of adjacent subcutaneous adipose tissue. As the gold standard for IHL quantification, single-voxel stimulated echo magnetic resonance spectroscopy (MRS) was applied. IHL(MRS) was quantified using the water peak as a reference.Results: Forty-five MR examinations could be performed, and IHL(MRS) content ranged from 0.7% to 19.1%. Results from MRS and fat-selective imaging correlated well with Spearman coefficients between r = 0.78 and r = 0.86. There were no relevant regional differences in IHL within the liver parenchyma (p > 0.6359). Fat-selective imaging was able to reliably identify patients with IHL content above 5% with positive/negative likelihood ratio of 11.8 and 0.05, respectively.Conclusion: Fat-selective MR imaging provides both a reliable and a convenient method of rapidly quantifying IHL content in obese adolescents. [ABSTRACT FROM AUTHOR]

Published
2011
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