Total and CO-reactive heme content of actinorhizal nodules and the roots of some non-nodulated plants

The concentration of total and CO-reactive heme was measured in actinorhizal nodules from six different genera. This gave the upper limit to hemoglobin concentration in these nodules. Quantitative extraction of CO-reactive heme was achieved under anaerobic conditions in a buffer equilibrated with CO and containing Triton X-100. The concentration of CO-reactive heme in nodules of Casuarina and Myrica was approximately half of that found in legume nodules, whereas in Comptonia, Alnus and Ceanothus the concentrations of heme were about 10 times lower than in legume nodules. There was no detectable CO-reactive heme in Datisca nodules, but low concentrations were detected in roots of all non-nodulating plants examined, including Zea mays . Difference spectra of CO treated minus dithionite-reduced extracts displayed similar wavelengths of maximal and minimal light absorption for all extracts, and were consistent with those of a hemoglobin. The concentration of CO-reactive heme was not correlated to the degree to which CO inhibited nitrogenase activity nor was it affected by reducing the oxygen concentration in the rooting zone. However, there was a positive correlation between heme concentration and suberization or lignification of the walls of infected host cells. These observations demonstrate that, unlike legume nodules, high concentrations of heme or hemoglobin are not needed for active nitrogen fixation in most actinorhizal nodules. Nonetheless, a significant amount of CO-reactive heme is found in the nodules of Alnus, Comptonia, and Ceanothus, and in the roots of Zea mays . The identity and function of this heme is unknown.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43460/1/11104_2006_Article_BF02370943.pd

A model describing photosynthesis in terms of gas diffusion and enzyme kinetics

A model predicting net photosynthesis of individual plant leaves for a variety of environmental conditions has been developed. It is based on an electrical analogue describing gas diffusion from the free atmosphere to the sites of CO 2 fixation and a Michaelis-Menten equation describing CO 2 fixation. The model is presented in two versions, a simplified form without respiration and a more complex form including respiration. Both versions include terms for light and temperature dependence of CO 2 fixation and light control of stomatal resistance. The second version also includes terms for temperature, light, and oxygen dependence of respiration and O 2 dependence of CO 2 fixation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47495/1/425_2004_Article_BF00387066.pd

CHAMP. A challenging micro-satellite payload for geophysical research and application Feasibility study. Final report

CHAMP is a mini-satellite concept, defined by researchers of the GeoForschungsZentrum Potsdam in its primary mission goals and basic payload elements and studied in its feasibility over the last six months by a team of 12 space related companies from the 'new states' in Germany. The feasibility study became possible by the initiative of the German Space Agency DARA to support a so-called 'NBL Leitprojekt', a lead project of the East-German space industry. The feasibility study, which is presented in this report, is the first step towards the realization of the concept, foreseen already for 1998, when the satellite is planned to be launched. CHAMP with its multi-purpose payload could substantially contribute to one of the basic research objectives of studies of the planet Earth, that is to the - determination of the composition, structure, dynamics of the solid planet, its oceans and atmosphere, and its surrounding envelope of charged particles and fields. (orig.)SIGLEAvailable from TIB Hannover: F96B628+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA) GmbH, Bonn (Germany)DEGerman

CHAMP PhaseB - Executive Summary

The small satellite mission CHAMP was initiated and is primarily funded by the German Space Agency (DARA) as a lead project for the East German space industry. It is defined in its main mission goals by researchers of the GeoForschungsZentrum Potsdam (GFZ), and is conducted under lead of GFZ in cooperation with the German Aerospace Establishment (DLR) and the industry. After completion of an initial feasibility study (Phase A) and of the project's definition/specification phase (Phase B), followed by a two months redesign phase (Phase #DELTA#B), CHAMP is supposed to enter into Phase C/D in late 1996. CHAMP as a geoscientific mission with a multi-purpose and complementary payload shall substantially contribute to one of the basic research objectives of studies of planet Earth, that is, to the determination of the composition, structure, and dynamics of the solid planet, its oceans and atmosphere, and its surrounding envelope of charged particles and fields. CHAMP being one element in a timely sequence of Earth observations and platforms, satellites, and mini-satellites could be a contributor to the acquisition of global, synoptic and long-term measurements of global processes through space and ground instrumentation. CHAMP shall fulfil the criteria of a small satellite mission, i.e., only a few years of development time through the usage of existing sensors and commercial spacecraft subsystem components, and reduced costs through protoflight approach, reduced quality standards and test efforts. The most challenging parts of the CHAMP mission are the variety of payload components especially the accelerometer and the magnetometers, each one with demanding environmental requirements. It is designed to observe both the gravitational as well as the magnetic potential from one platform in order to get a complementary scientific payback. The GPS-receiver on-board CHAMP being employed for gravity field recovery, simultaneously will perform atmosphere and ionosphere profiling by Earth limb sounding. It is also for the first time a three-axes accelerometer will be flown to measure with a required accuracy of 10"-"8 m/s"2 the non-gravitational forces, e.g. air drag, perturbing the satellite's motion. (orig.)SIGLEAvailable from TIB Hannover: RR 6134(96/13) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman