A Data Analysis of the Irradiation Parameter D10 for Bacteria and Spores under Various Conditions

Gerwen, Suzanne J.C. van; Rombouts, F.M.; Riet, K. van ’t; Zwietering, Marcel H.

doi:10.4315/0362-028x-62.9.1024

Cited by 59 publications

(46 citation statements)

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“…H. salinarum is also extremely resistant to X-ray irradiation. The D 10 values (10% survival) are 10 kGy for D. radiodurans and 5 kGy for H. salinarum [27], [28]. For comparison, the D 10 value of E. coli is 0.25 kGy [29].…”

Section: Discussionmentioning

confidence: 99%

Regulated Polyploidy in Halophilic Archaea

et al. 2006

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Polyploidy is common in higher eukaryotes, especially in plants, but it is generally assumed that most prokaryotes contain a single copy of a circular chromosome and are therefore monoploid. We have used two independent methods to determine the genome copy number in halophilic archaea, 1) cell lysis in agarose blocks and Southern blot analysis, and 2) Real-Time quantitative PCR. Fast growing H. salinarum cells contain on average about 25 copies of the chromosome in exponential phase, and their ploidy is downregulated to 15 copies in early stationary phase. The chromosome copy number is identical in cultures with a twofold lower growth rate, in contrast to the results reported for several other prokaryotic species. Of three additional replicons of H. salinarum, two have a low copy number that is not growth-phase regulated, while one replicon even shows a higher degree of growth phase-dependent regulation than the main replicon. The genome copy number of H. volcanii is similarly high during exponential phase (on average 18 copies/cell), and it is also downregulated (to 10 copies) as the cells enter stationary phase. The variation of genome copy numbers in the population was addressed by fluorescence microscopy and by FACS analysis. These methods allowed us to verify the growth phase-dependent regulation of ploidy in H. salinarum, and they revealed that there is a wide variation in genome copy numbers in individual cells that is much larger in exponential than in stationary phase. Our results indicate that polyploidy might be more widespread in archaea (or even prokaryotes in general) than previously assumed. Moreover, the presence of so many genome copies in a prokaryote raises questions about the evolutionary significance of this strategy.

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Section: Discussionmentioning

confidence: 99%

Regulated Polyploidy in Halophilic Archaea

et al. 2006

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“…The presence of oxygen during irradiation and consequently the formation of oxygen radicals have been found to increase the deleterious effects of irradiation. 32 Radicals are thus considered to be very important mediators of cell injury and/or death. 33 Substantial damage to cellular components was visualized from the spectral differences between control and irradiated cells, particularly after an irradiation dose of 7.55 kGy.…”

Section: Discussion Cellular Irradiation Damagementioning

confidence: 99%

Fourier transform IR spectroscopic appraisal of radiation damage in Micrococcus luteus

et al. 2003

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Fourier transform IR spectroscopy (FTIR) is used to analyze cells of Micrococcus luteus, the type species of the highly heterogeneous genus Micrococcus that belongs to the Micrococcaceae family. The cells of M. luteus, which is a Gram-positive and yellow-pigmented bacterium, are submitted to increasing doses of gamma radiation. Irradiation leads to the generation of reactive oxygen species that induce biochemical changes as shown in spectral profiles. Beyond a dose of 0.70 kGy, significant differences between samples are observed, particularly in the 1485-900 cm(-1) region, which contains information about membrane lipids, cell wall polysaccharides, and nucleic acids. After a dose of 16.50 kGy, M. luteus is reincubated for times ranging from 1 to 24 h. Postirradiation reincubated bacteria are found far from the control and irradiated cells (mainly in the 985-900 cm(-1) range), suggesting that a biomolecular rearrangement occurs as soon as reincubation begins in the growth medium. Thus, FTIR spectroscopy appears to be a very useful technique for the rapid visualization of the alterations induced by both the radiation and mutagenic response during reincubation. The use of mathematical methods gives good insight into the biomolecular compounds involved in these two mechanisms. In view of these preliminary results, we hypothesize that it can be successfully applied to any type of tissue and that it may be a future interesting tool for evaluating the effects of radiation in humans.

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“…However, a generalization can be made for bacteria with respect to Gram staining: most of the radiation-resistant bacteria reported are Gram positive, with the exception of a radiationresistant Gram-negative cyanobacterium, Chroococcidiopsis (gamma radiation dose that yields a 10% survival rate [D 10 ] of 5 kGy) (57), while most of the radiation-sensitive bacteria are Gram negative, with one of the exceptions being the radiationsensitive Gram positive Micrococcus luteus (Sarcina lutea) (409). Other radiation-resistant bacteria unrelated to members of the Deinococcaceae include Rubrobacter radiotolerans (674), Rubrobacter xylanophilus (186), Kocuria rosea (76), Methylobacterium radiotolerans (214), Lactobacillus plantarum (244), Acinetobacter radioresistens (461), Enterococcus faecium (634), Hymenobacter actinosclerus (103), and Kineococcus radiotolerans (492). Radiation resistance is widespread among hyperthermophilic archaea, for example, Pyrococcus furiosus (145), Desulfurococcus amylolyticus, Thermococcus stetteri (315), Thermococcus gammatolerans (276), and Halobacterium (321).…”

Section: Ecology Of D Radioduransmentioning

confidence: 99%

Oxidative Stress Resistance inDeinococcus radiodurans

Slade

Radman

2011

Microbiol Mol Biol Rev

648

639

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SUMMARY Deinococcus radiodurans is a robust bacterium best known for its capacity to repair massive DNA damage efficiently and accurately. It is extremely resistant to many DNA-damaging agents, including ionizing radiation and UV radiation (100 to 295 nm), desiccation, and mitomycin C, which induce oxidative damage not only to DNA but also to all cellular macromolecules via the production of reactive oxygen species. The extreme resilience of D. radiodurans to oxidative stress is imparted synergistically by an efficient protection of proteins against oxidative stress and an efficient DNA repair mechanism, enhanced by functional redundancies in both systems. D. radiodurans assets for the prevention of and recovery from oxidative stress are extensively reviewed here. Radiation- and desiccation-resistant bacteria such as D. radiodurans have substantially lower protein oxidation levels than do sensitive bacteria but have similar yields of DNA double-strand breaks. These findings challenge the concept of DNA as the primary target of radiation toxicity while advancing protein damage, and the protection of proteins against oxidative damage, as a new paradigm of radiation toxicity and survival. The protection of DNA repair and other proteins against oxidative damage is imparted by enzymatic and nonenzymatic antioxidant defense systems dominated by divalent manganese complexes. Given that oxidative stress caused by the accumulation of reactive oxygen species is associated with aging and cancer, a comprehensive outlook on D. radiodurans strategies of combating oxidative stress may open new avenues for antiaging and anticancer treatments. The study of the antioxidation protection in D. radiodurans is therefore of considerable potential interest for medicine and public health.

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A Data Analysis of the Irradiation Parameter D10 for Bacteria and Spores under Various Conditions

Cited by 59 publications

References 0 publications

Regulated Polyploidy in Halophilic Archaea

Regulated Polyploidy in Halophilic Archaea

Fourier transform IR spectroscopic appraisal of radiation damage in Micrococcus luteus

Oxidative Stress Resistance inDeinococcus radiodurans

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