Stress and signal effect of gravity changes on microorganisms Final report / Stress- und Signalwirkung von Gravitations-Aenderungen auf Mikroorganismen Schlussbericht
- Authors
- Publication Date
- Jan 01, 1997
- Source
- OpenGrey Repository
- Keywords
- Language
- German
- License
- Unknown
Abstract
Hypergravity and simulated weightlessness were used to check whether cyanobacteria respond to changes in gravity showing a stress-like behaviour. Hypergravity generated by a low-speed centrifuge increased slightly the brutto activity of dehydrogenases, but the increase was equal for 90 and 180 x g. Similarly, the protein pattern did not show qualitative alterations during hypergravity (up to 180 x g): when subjected to common stresses like salt, heat and light the cyanobacterium studied (Synechocystis PCC 6803) clearly accumulated at least 4 stress proteins (62, 32, 30 and 26 kDa, resp.). Three of these proteins could be detected after hypergravity, too, but in such small amounts that their occurrence could only be taken as a weak indication of stress. Low-molecular weight stress metabolites were not synthesized in response to hypergravity indicating that this gravity change was unable to active mechanosensors of other signal transduction chains. Gravity-dependent alterations were only observed during simulated weightlessness (generated by a fast-rotating clinostate): the glutamate/glutamine ratio was significantly shifted toward a higher glutamine portion. This could be interpreted by lower levels of energy metabilities found earlier under #mu#g conditions. Altogether, the results may show that moderate changes of gravity were hardly, if ever, sensed as stress by cyanobacteria. (orig.) / SIGLE / Available from TIB Hannover: DtF QN1(50,50) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische Informationsbibliothek / Bundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany) / DE / Germany