Michael Schröder

Bio: Michael Schröder is an academic researcher from Max Planck Society. The author has contributed to research in topics: Nondestructive testing & Radiographic testing. The author has an hindex of 4, co-authored 6 publications receiving 42 citations.

Molecular analysis of de novo pyrimidine synthesis in solanaceous species.

Abstract: The de novo synthesis of pyrimidine nucleotides in plants has been analysed on a molecular level with special focus on cDNA cloning and structure analysis of all genes involved and their expression pattern during development. The exhaustive cloning of all cDNAs resulted from screening with heterologous cDNAs or by using complementation strategies with Escherichia coli mutants and subsequent enzyme activity measurements. Southern hybridization and comparison with the Arabidopsis genome reveals plant specific aspects and a simple genomic organization of pyrimidine synthesis in plants, which is superimposed by the postulated, complex subcellular compartmentalization. Northern hybridization evinces coordinated expression of all genes under developmental control during tobacco leaf growth.

Quality assurance measures during tightening of various bolts at Wendelstein 7-X

Abstract: The central part of W7-X is the main magnet system, consisting of 50 non-planar and 20 planar superconducting coils which are fixed to a rigid central support structure. For further stiffening of the magnet system various inter-coil connection elements are used which are either welded or bolted to the coils. The bolts and screws from M20 to M90 are made from high-strength Inconel 718 as well as the tightening elements called Superbolts ® . In order to cope with the very large mechanical loads at 4 K due to the Lorentz-forces and to provide a secure connection, all bolts are pre-tensioned close to the elastic yield limit. Therefore the measurement of the preload must be done very carefully with an accuracy of better than 5%. This measurement is made by using the ultrasonic method. Since parameters like Young's modulus, speed of sound, temperature, etc., influence this measurement; an individual calibration must be performed for each specific charge of material and each specific dimension. Special attention must be paid to the short bolts with small grip length. Their stretching under full load often is only 1/10 mm. The paper will describe the procedure of tensioning, the structure of the database for the calibration data, the experiences with the reproducibility and accuracy of the measurement.

Quality assurance of aluminium weld seams and cast casings of the W7-X coils

Abstract: The WENDELSTEIN 7-X stellarator is the next step device in the stellarator line of IPP Garching. It is presently being assembled in the branch institute of IPP at Greifswald. The central part of W7-X is the superconducting magnet system. It comprises 50 non-planar and 20 planar coils. This contribution outlines for two critical examples of the magnet system the quality assurance measures applied, namely for the aluminium weld seams at the superconductor cable during the assembly and for the cast steel casings of the non-planar coils during manufacture.

Pyrimidine and Purine Biosynthesis and Degradation in Plants

Abstract: Nucleotide metabolism operates in all living organisms, embodies an evolutionarily ancient and indispensable complex of metabolic pathways and is of utmost importance for plant metabolism and development. In plants, nucleotides can be synthesized de novo from 5-phosphoribosyl-1-pyrophosphate and simple molecules (e.g., CO2, amino acids, and tetrahydrofolate), or be derived from preformed nucleosides and nucleobases via salvage reactions. Nucleotides are degraded to simple metabolites, and this process permits the recycling of phosphate, nitrogen, and carbon into central metabolic pools. Despite extensive biochemical knowledge about purine and pyrimidine metabolism, comprehensive studies of the regulation of this metabolism in plants are only starting to emerge. Here we review progress in molecular aspects and recent studies on the regulation and manipulation of nucleotide metabolism in plants.

Status of Wendelstein 7-X construction

Abstract: Wendelstein 7-X (W7-X) represents the continuation of fusion experiments of the stellarator type at the Max-Planck Institute for Plasma Physics (IPP). The aim of W7-X is to demonstrate the suitability for a fusion reactor of this alternative type of magnetically confined plasma experiment. W7-X is being built at Greifswald in the northeast of Germany. The size of device (725 tons, height of 5 m, diameter 16 m) and the superconductive magnet system distinguish W7-X from earlier stellarators at IPP. The paper provides a summary of the status of the main components, the mastering of the technical challenges during component acceptance testing and during machine assembly. Latest results of the assembly work are especially highlighted. The scope of the construction of W7-X was modified and additional acceleration measures were implemented to mitigate risks and delays. Some aspects of these changes are explained in this paper.

Nucleobase and nucleoside transport and integration into plant metabolism

Abstract: Nucleotide metabolism is an essential process in all living organisms. Besides newly synthesized nucleotides, the recycling (salvage) of partially degraded nucleotides, i.e., nucleosides and nucleobases serves to keep the homeostasis of the nucleotide pool. Both types of metabolites are substrates of at least six families of transport proteins in Arabidopsis thaliana (Arabidopsis) with a total of 49 members. In the last years several members of such transport proteins have been analyzed allowing to present a more detailed picture of nucleoside and nucleobase transport and the physiological function of these processes. Besides functioning in nucleotide metabolism it turned out that individual members of the before named transporters exhibit the capacity to transport a wide range of different substrates including vitamins and phytohormones. The aim of this review is to summarize the current knowledge on nucleobase and nucleoside transport processes in plants and integrate this into nucleotide metabolism in general. Thereby, we will focus on those proteins which have been characterized at the biochemical level.

The OsDHODH1 gene is involved in salt and drought tolerance in rice.

Abstract: In the present paper, we identified and cloned OsDHODH1 encoding a putative cytosolic dihydroorotate dehydrogenase (DHODH) in rice. Expression analysis indicated that OsDHODH1 is upregulated by salt, drought and exogenous abscisic acid (ABA), but not by cold. By prokaryotic expression, we determined the enzymatic activity of OsDHODH1 and found that overproduction of OsDHODH1 significantly improved the tolerance of Escherichia coli cells to salt and osmotic stresses. Overexpression of the OsDHODH1 gene in rice increased the DHODH activity and enhanced plant tolerance to salt and drought stresses as compared with wild type and OsDHODH1-antisense transgenic plants. Our findings reveal, for the first time, that cytosolic dihydroorotate dehydrogenase is involved in plant stress response and that OsDHODH1 could be used in engineering crop plants with enhanced tolerance to salt and drought.