RESUMO
In long duration space experiments Rice caryopses and embryos, which are able to remain alive 10 years (or more) and tolerate extreme physical conditions (temperature, few water content) during irradiation and post-irradiation storage, were used (8, 40, 201 and 457 days on board of Salyut 7, 2107 days on LDEF). In certain experiments (Salyut 7), samples were irradiated either before or after the flight. Effects of the flight and radiosensitivity were observed in Rice seedlings cultivated in in vitro conditions. Statistical results indicate an increase in radiosensitivity when irradiations occur before the flight. Microanalyses were made in different parts of one caryopsis and of one embryo, and the results compared with those of control samples. With caryopses and embryos of the same Rice varieties, but from LDEF, we made the same kinds of experiments to compare results.
Assuntos
Raios gama , Oryza/efeitos da radiação , Sementes/crescimento & desenvolvimento , Sementes/efeitos da radiação , Voo Espacial , Ausência de Peso , Radicais Livres , Germinação/efeitos da radiação , Minerais , Oryza/citologia , Oryza/embriologia , Oryza/crescimento & desenvolvimento , Tolerância a Radiação , Sementes/citologia , Astronave , Fatores de TempoRESUMO
Three french laboratories have participated in the Free Flyer Biostack experiment. Artemia cysts, tobacco seeds and rice caryopsis and embryos were used. Biological objects in monolayers were dead. In opposite, a large fraction of samples used in bulk survived. A stimulatory effect occurred in the first steps of development in Artemia cysts. In fact, the larval survival was unchanged or slightly reduced. In tobacco a drastic decrease in germination and survival rate was observed. Space flight did not induce genetic changes. In rice, results depend on the variety which was investigated; the growth rate stimulation in flight samples is discussed with respect to controls.
Assuntos
Artemia/efeitos da radiação , Radiação Cósmica , Germinação/efeitos da radiação , Nicotiana/efeitos da radiação , Oryza/efeitos da radiação , Plantas Tóxicas , Voo Espacial/instrumentação , Animais , Artemia/embriologia , Artemia/genética , Raios gama , Oryza/genética , Oryza/crescimento & desenvolvimento , Sementes/efeitos da radiação , Astronave , Dosimetria Termoluminescente , Fatores de Tempo , Nicotiana/genética , Nicotiana/crescimento & desenvolvimentoRESUMO
Rice caryopsis of Cigalon variety with short grain of the LDEF mission can develop and grow as well as those of the laboratory control. Rice caryopsis of Delta variety with long grain did not develop while a small number of excised embryos can develop and grow as well as the control group. A preliminary study of the Electron Spin Resonance (ESR) spectra of Rice embryos and seeds recorded several month after the flight on flight samples and on control ones has been carried out. All these samples had the same storage time. During storage the radical concentration which usually decreases, now depends on irradiation doses and on whether or not they were delivered in presence of oxygen. The signal variations are smaller than those usually observed in the different parts of the starch. An estimation of a "gamma-equivalent-dose" can be reached.
Assuntos
Oryza/crescimento & desenvolvimento , Oxigênio , Sementes/efeitos da radiação , Voo Espacial , Radiação Cósmica , Meios de Cultura , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres , Raios gama , Oryza/embriologia , Oryza/efeitos da radiação , Doses de Radiação , Sementes/crescimento & desenvolvimento , Astronave , ÁguaRESUMO
Caryopses and isolated embryos from Rice (Oryza sativa L.) and Tobacco seeds (Nicotiana tabacum L. variety Xanthi) were studied in the Biobloc III container aboard the Soviet orbital space station SALYUT 7. The recovery from radiation damage under conditions of space flight was observed for rice caryopsis and embryos gamma irradiated (Co 60, 50 grays) prior to launch. There was a large decrease in the percentage of germinating seeds from the Tobacco strain tested when the seeds were exposed to heavy ions. Among the germinating plantlets there were few morphological anomalies. Furthermore, there was a significant greater amount of genetic change in those samples held in grids as compared to those in bags.
Assuntos
Íons Pesados , Brotos de Planta/efeitos da radiação , Sementes/crescimento & desenvolvimento , Sementes/efeitos da radiação , Voo Espacial , Ausência de Peso , Radiação Cósmica , Cotilédone/efeitos da radiação , Raios gama , Germinação/efeitos da radiação , Oryza/crescimento & desenvolvimento , Oryza/efeitos da radiação , Brotos de Planta/crescimento & desenvolvimento , Plantas Tóxicas , Sementes/genética , Nicotiana/genética , Nicotiana/crescimento & desenvolvimento , Nicotiana/efeitos da radiaçãoRESUMO
The 3 natural cytokinins contained both in the extracts and RNA of yeast and the tumor tissues cultivated in vitro, elicit radiorestorative properties from the crown-gall tissues of Scorsonera submitted to Co60 gamma-rays. However the cytokinins produce no stimulating effect whatsoever on the non irradiated tissues that are nontheless highly stimulated by yeast extract and their RNA.