Effect of heavy ion irradiation on DNA DSB repair in Methanosarcina barkeri.
TL;DR: DNA double strand break repairing ability of mesophilic archaea Methanosarcina barkeri (DSM 804) was studied using (7)Li, (12)C and (16)O heavy ions and compared with that of (60)Co gamma-rays.
About: This article is published in Anaerobe.The article was published on 2003-02-01. It has received 5 citations till now. The article focuses on the topics: Methanosarcina barkeri.
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TL;DR: In this paper, high-density DNA microarrays were used to characterize the genome-wide transcriptional response of the hyperthermophilic, aerobic crenarchaeote Sulfolobus solfataricus to UV damage.
Abstract: In order to characterize the genome-wide transcriptional response of the hyperthermophilic, aerobic crenarchaeote Sulfolobus solfataricus to UV damage, we used high-density DNA microarrays which covered 3,368 genetic features encoded on the host genome, as well as the genes of several extrachromosomal genetic elements. While no significant up-regulation of genes potentially involved in direct DNA damage reversal was observed, a specific transcriptional UV response involving 55 genes could be dissected. Although flow cytometry showed only modest perturbation of the cell cycle, strong modulation of the transcript levels of the Cdc6 replication initiator genes was observed. Up-regulation of an operon encoding Mre11 and Rad50 homologs pointed to induction of recombinational repair. Consistent with this, DNA double-strand breaks were observed between 2 and 8 h after UV treatment, possibly resulting from replication fork collapse at damaged DNA sites. The strong transcriptional induction of genes which potentially encode functions for pilus formation suggested that conjugational activity might lead to enhanced exchange of genetic material. In support of this, a statistical microscopic analysis demonstrated that large cell aggregates formed upon UV exposure. Together, this provided supporting evidence to a link between recombinational repair and conjugation events.
125 citations
TL;DR: After desiccation M. barkeri has the innate capability to survive extended periods of exposure to air and lethal temperatures, and the protection mechanisms are likely adequate to maintain cell viability during periodic exposure events.
Abstract: Viable methanogens have been detected in dry, aerobic environments such as dry reservoir sediment, dry rice paddies and aerobic desert soils, which suggests that methanogens have mechanisms for long-term survival in a desiccated state. In this study, we quantified the survival rates of the methanogenic archaeon Methanosarcina barkeri after desiccation under conditions equivalent to the driest environments on Earth and subsequent exposure to different stress factors. There was no significant loss of viability after desiccation for 28 days for cells grown with either hydrogen or the methylotrophic substrates, but recovery was affected by growth phase, with cells desiccated during the stationary phase of growth having a higher rate of recovery after desiccation. Synthesis of methanosarcinal extracellular polysaccharide (EPS) significantly increased the viability of desiccated cells under both anaerobic and aerobic conditions compared with that of non-EPS-synthesizing cells. Desiccated M. barkeri exposed to air at room temperature did not lose significant viability after 28 days, and exposure of M. barkeri to air after desiccation appeared to improve the recovery of viable cells compared with that of desiccated cells that were never exposed to air. Desiccated M. barkeri was more resistant to higher temperatures, and although resistance to oxidative conditions such as ozone and ionizing radiation was not as robust as in other desiccation-resistant microorganisms, the protection mechanisms are likely adequate to maintain cell viability during periodic exposure events. The results of this study demonstrate that after desiccation M. barkeri has the innate capability to survive extended periods of exposure to air and lethal temperatures.
42 citations
TL;DR: In this paper, the effects of low-dose carbon ion irradiation on reproductive system of mice were investigated by measuring DNA double-strand breaks (DNA DSBs) and oxidative stress parameters including malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, and testis weight and sperm count at 12h, 21d and 35d after irradiation in mouse testis.
9 citations
01 Jan 2012
2 citations
TL;DR: The strain was one of the members of the group of uncultivated bacterium as evident from phylogenetic analysis, thus indicating the successful cultivation of an as yet uncultivable novel microbe and also the non-specific growth of microbes in prescribed medium.
Abstract: Problem statement: This study was an attempt to isolate anaerobic microbes with potential for DNA double strand break repair using methanogen specific medium (DSMZ 120) from East Calcutta Wetland in India. It also intended to verify the specificity of the medium for isolation of the desired family of microbe. Approach: Culture based technique was used to obtain the pure isolate that was further characterized in details. For double strand break repair studies, isolate was irradiated with different doses of 60Co gamma rays and its subsequent repair was observed using pulse field gel electrophoresis and asymmetric field inversion gel electrophoresis. Inhibitor was used to predict the mechanism of repair. Results: In this study we isolated and characterized a metal sensitive anaerobic microbial strain obtained using methanogen specific medium (DSMZ 120) from East Calcutta Wetland in India. The strain was one of the members of the group of uncultivated bacterium as evident from phylogenetic analysis, thus indicating the successful cultivation of an as yet uncultivable novel microbe (GenBank Acc. No. FJ 930097) and also the non-specific growth of microbes in prescribed medium. It was a Gram positive Bacilli, member of Fermicutes with optimum growth at 25°C and pH-7. The growth curve analysis showed a lag phase up to 24 h, log phase from 24-48 h, an early stationary phase from 96 h onwards. The strain could repair the DNA double strand break caused by irradiation with 60Co γ rays. The dose profile study revealed maximum repair at 60 Grays and thereafter a drop in repair ability with increase in irradiation dose. The time required for repair showed an essential incubation period of 4 h. The DNA polymerase inhibitor, Arabinose CTP inhibited the repair indicating the involvement of polymerase in the repair process and thus pointing towards homologous recombination as the underlying mechanism. Conclusion: In this study we were able to cultivate an as yet uncultivable anaerobic bacterial isolate and predict the growth conditions for the isolate. On irradiation with 60Co γ rays the isolate showed maximum repair following 60 Gray damage. DNA polymerase inhibitor arabinose CTP inhibited the repair mechanism completely. This indicated that DNA polymerase took active part in repair process and thus the mechanism was that of homologous recombination repair.
1 citations
Cites background from "Effect of heavy ion irradiation on ..."
...It is at par wi th the finding of Raychaudhuri et al.([2]) in case of methanogen....
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...Methanogens are closer to bacteria in their morphol ogy while being closer to their eukaryotic counterpart in he information processing systems ([2])....
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...Prediction of the mechanism of repair by using inhibitor: Arabinosine CTP, a polymerase inhibitor had been used to check the involvement of polymerase in the repair process as recombination repair would be affected by polymerase inhibitor while NHEJ would not be affected....
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...In bacteria and yeast homologous recombination is the process for repairing the DNA double strand break, while vertebrates mostly repai r the double strand breaks in DNA by Non-Homologous End Joining (NHEJ) ([2,3])....
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...It is at par with the finding of Raychaudhuri et al.[2] in case of methanogen....
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References
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01 Oct 1989-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the effects of heavy charged particles on radioprotection problems in manned space flights and for the increasing use of heavy ions in radiotherapy are discussed. But the experimental solution of these and other biology-specific problems is discussed and a general outline of the experiments is given.
Abstract: The radiobiological effects of heavy charged particles are of fundamental interest for the understanding of radioprotection problems in manned space flights and for the increasing use of heavy ions in radiotherapy. Therefore, an increasing number of radiobiological experiments are performed at heavy-ion accelerators. In these experiments biological targets such as, for instance, cultures of living mammalian cells have to be irradiated under sterile conditions and atmospheric pressure. The experimental solution of these and other biology-specific problems is discussed and a general outline of the experiments is given.
25 citations
28 Jan 1992
9 citations
TL;DR: The involvement of polymerase indicates recombination to be the underlying mechanism in DSB repair of Methanosarcina barkeri, a mesophilic archaeon investigated for DNA double strand break repair following60Co- γ irradiation.
6 citations