Inactivation, mutation induction and repair in Bacillus subtilis spores irradiated with heavy ions

Horneck, G.; Bücker, H.

doi:10.1016/0273-1177(83)90177-1

Cited by 18 publications

(2 citation statements)

References 18 publications

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“…To recover the spores from the quartz discs after treatments, the spore monolayer was covered by a 10% aqueous polyvinyl alcohol solution; after air drying, the spore-polyvinyl alcohol layer was stripped off as described previously (19). Spores were resuspended in 1 ml sterile distilled water, resulting in Ͼ95% recovery of the spores.…”

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Role of DNA Repair by Nonhomologous-End Joining in Bacillus subtilis Spore Resistance to Extreme Dryness, Mono- and Polychromatic UV, and Ionizing Radiation

et al. 2007

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The role of DNA repair by nonhomologous-end joining (NHEJ) in spore resistance to UV, ionizing radiation, and ultrahigh vacuum was studied in wild-type and DNA repair mutants (recA, splB, ykoU, ykoV, and ykoU ykoV mutants) of Bacillus subtilis. NHEJ-defective spores with mutations in ykoU, ykoV, and ykoU ykoV were significantly more sensitive to UV, ionizing radiation, and ultrahigh vacuum than wild-type spores, indicating that NHEJ provides an important pathway during spore germination for repair of DNA double-strand breaks.It has been shown that endospores of gram-positive bacteria can remain viable for at least thousands of years (5, 44, 54; reviewed in reference 31). Bacterial spores persist in a metabolically inactive state, and environmental damage to spore cellular components accumulates unrepaired until germination and outgrowth (32). However, Bacillus subtilis spores are highly resistant to different environmental stresses, such as toxic chemicals and biocidal agents, desiccation, pressure and temperature extremes, and ionizing and UV radiation. The reason for this high resistance to environmental extremes lies partly in the spore structure itself: spores possess thick layers of highly cross-linked coat proteins (13), a modified peptidoglycan spore cortex, and abundant intracellular constituents such as the calcium chelate of dipicolinic acid and small, acidsoluble spore proteins (␣/␤-type SASP), as protectants of spore DNA (46, 50). Binding of ␣/␤-type SASP to spore DNA, coupled with spore core dehydration, appears to change the helical conformation of spore DNA from the B form to an A-like form (34, 48), which in turn alters its UV photochemistry to favor the production of 5-thyminyl-5,6-dihydrothymine, the unique spore-specific spore photoproduct (SP) (8,32,35,50). For the removal of the SP, spores possess an SP-specific repair enzyme called SP lyase, encoded by the splB gene, that monomerizes the SP dimer back to two thymine residues in an adenosyl-radical-dependent reaction (4,28,42).While the UV photochemistry of spore DNA and the repair of UV damage to DNA during germination are well described (12,32,33,47,50), there has been relatively little work on the nature of DNA damage in spores caused by ionizing radiation or extreme dryness and on the occurrence of a specific DNA repair system(s) for repair of this damage. It is assumed that DNA double-strand breaks (DSB), which are the most critical damage caused by ionizing radiation (57) and desiccation (9, 10, 39) in vegetative cells, are also induced in bacterial spores. Spores of B. subtilis contain a single chromosome arranged in a toroidal shape (16, 41); therefore, the homologous recombination pathway, which requires at least two homologous chromosomes, cannot operate on DSB during spore germination (55). An alternative repair pathway for DSB induced in spore DNA, nonhomologous-end joining (NHEJ) (3, 56), is considered here. This pathway as it occurs in eukaryotic cells requires a DNA end-binding component called Ku (Ku70 and Ku80) (58). The fir...

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confidence: 99%

Role of DNA Repair by Nonhomologous-End Joining in Bacillus subtilis Spore Resistance to Extreme Dryness, Mono- and Polychromatic UV, and Ionizing Radiation

et al. 2007

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“…To recover the spores from the quartz discs after irradiation, spore monolayers were covered by a 10% aqueous polyvinyl alcohol solution, and after drying the spore polyvinyl alcohol layer was stripped off as described previously (22,26) and was resuspended in 1 ml sterile distilled water, resulting in Ͼ95% recovery of the spores. This procedure does not affect spore viability (26).…”

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Roles of the Major, Small, Acid-Soluble Spore Proteins and Spore-Specific and Universal DNA Repair Mechanisms in Resistance of Bacillus subtilis Spores to Ionizing Radiation from X Rays and High-Energy Charged-Particle Bombardment

et al. 2008

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The role of DNA repair by nonhomologous end joining (NHEJ), homologous recombination, spore photoproduct lyase, and DNA polymerase I and genome protection via ␣/␤-type small, acid-soluble spore proteins (SASP) in Bacillus subtilis spore resistance to accelerated heavy ions (high-energy charged [HZE] particles) and X rays has been studied. Spores deficient in NHEJ and ␣/␤-type SASP were significantly more sensitive to HZE particle bombardment and X-ray irradiation than were the recA, polA, and splB mutant and wild-type spores, indicating that NHEJ provides an efficient DNA double-strand break repair pathway during spore germination and that the loss of the ␣/␤-type SASP leads to a significant radiosensitivity to ionizing radiation, suggesting the essential function of these spore proteins as protectants of spore DNA against ionizing radiation.Endospores of the gram-positive bacterium Bacillus subtilis are highly resistant to inactivation by environmental stresses, such as biocidal agents and toxic chemicals, desiccation, pressure and temperature extremes, and high fluences of UV radiation (reviewed in references 44, 45, and 61) and are a powerful biodosimetric system for terrestrial environmental monitoring and astrobiological studies (44). On Earth, understanding extreme spore resistance to ionizing radiation is important in the areas of food preservation, medical sterilization, and decontamination from bioterror attack (4, 17, 47; reviewed in references 42 and 43). Off Earth, spore radiation resistance is important both in space flight and in ground-based simulations, in order to obtain information on the biological damage produced by exposure to space conditions (23,25,26,44). Onboard several spacecraft (Apollo 16, Spacelab 1, LDEF, D2, and FOTON), spores of Bacillus subtilis were exposed to selected parameters of space, such as space vacuum and different spectral ranges of solar UV radiation and cosmic rays, applied separately or in combination (5, 9, 19-21, 23, 24, 26). Especially, the radiation environment on Earth, on Mars, in low-Earth orbit, and in deep space is typified by a wide variety of primary particles covering an extended range of energies. Galactic cosmic rays (GCR) are charged particles that originate from sources beyond our solar system. The distribution of GCR is believed to be isotropic throughout interstellar space. The spectrum of the GCR consists of 98% protons and heavier ions (baryon component) and 2% electrons and positrons (lepton component). The baryon component is composed of 87% protons, 12% helium ions (alpha particles), and the remaining 1% heavy ions of charge 3 from lithium to 92 from uranium. Due to their high abundance, iron ions are highly penetrating, giving them a large potential for radiobiological damage (3,21).While the UV photochemistry of spore DNA and repair of UV damage to DNA during germination are well characterized (34,44,(59)(60)(61), there has been relatively little work on the nature of DNA damage in spores caused by ionizing radiation, the protective role of...

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The Biostack Concept and Its Application in Space and at Accelerators: Studies on Bacillus Subtilis Spores

Horneck¹

1993

Biological Effects and Physics of Solar and Galactic Cosmic Radiation

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Inactivation, mutation induction and repair in Bacillus subtilis spores irradiated with heavy ions

Cited by 18 publications

References 18 publications

Role of DNA Repair by Nonhomologous-End Joining in Bacillus subtilis Spore Resistance to Extreme Dryness, Mono- and Polychromatic UV, and Ionizing Radiation

Role of DNA Repair by Nonhomologous-End Joining in Bacillus subtilis Spore Resistance to Extreme Dryness, Mono- and Polychromatic UV, and Ionizing Radiation

Roles of the Major, Small, Acid-Soluble Spore Proteins and Spore-Specific and Universal DNA Repair Mechanisms in Resistance of Bacillus subtilis Spores to Ionizing Radiation from X Rays and High-Energy Charged-Particle Bombardment

The Biostack Concept and Its Application in Space and at Accelerators: Studies on Bacillus Subtilis Spores

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