Heavy Ion Radiation Effects on Single Spores of Bacillus Subtilis
During spaceflight man is exposed to various stress factors including cosmic radiation. Therefore it is necessary to study the biological effectiveness of this peculiar kind of radiation. Among the different components of cosmic radiation, the heavy ions are of special concern. Since the high energy of a heavy ion is deposited in matter along the particle’s trajectory in a very small volume in a very short period of time, it is necessary to look for the effects of single heavy ions in individual biological objects. Such experiments have been carried out in space within the BIOSTACK program (Facius et. al. 1979, Bücker et. al. 1981). In these experiments, layers of biological objects were fixed on nuclear track detectors, such as cellulose nitrate. On single cells, such as bacterial spores of Bacillus subtilis which are 1 µm in diameter, it was demonstrated, first, that not every spore directly hit was inactivated, and, secondly, that also spores at some distance from the particle’s trajectory (up to app. 5 µm) were killed with a certain frequency. Similar results were found for spores on plastic detectors, irradiated with heavy ions from an accelerator ( Facius et. al. 1983). In all these investigations, the accuracy in determining the impact parameter i.e., the distance of the center of the spore from the particle’s trajectory, was 0.2 µm. Using AgCl (silver chloride) single crystal as detector onto which a monolayer of B. subtilis spores was fixed, an improved system has been developed with high accuracy in measuring.
KeywordsImpact Parameter Cosmic Radiation Bacterial Spore Nuclear Track Detector Subtilis Spore
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