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Sample records for sahara bacterium deinococcus

  1. Alliance of proteomics and genomics to unravel the specificities of Sahara bacterium Deinococcus deserti.

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    Arjan de Groot

    2009-03-01

    Full Text Available To better understand adaptation to harsh conditions encountered in hot arid deserts, we report the first complete genome sequence and proteome analysis of a bacterium, Deinococcus deserti VCD115, isolated from Sahara surface sand. Its genome consists of a 2.8-Mb chromosome and three large plasmids of 324 kb, 314 kb, and 396 kb. Accurate primary genome annotation of its 3,455 genes was guided by extensive proteome shotgun analysis. From the large corpus of MS/MS spectra recorded, 1,348 proteins were uncovered and semiquantified by spectral counting. Among the highly detected proteins are several orphans and Deinococcus-specific proteins of unknown function. The alliance of proteomics and genomics high-throughput techniques allowed identification of 15 unpredicted genes and, surprisingly, reversal of incorrectly predicted orientation of 11 genes. Reversal of orientation of two Deinococcus-specific radiation-induced genes, ddrC and ddrH, and identification in D. deserti of supplementary genes involved in manganese import extend our knowledge of the radiotolerance toolbox of Deinococcaceae. Additional genes involved in nutrient import and in DNA repair (i.e., two extra recA, three translesion DNA polymerases, a photolyase were also identified and found to be expressed under standard growth conditions, and, for these DNA repair genes, after exposure of the cells to UV. The supplementary nutrient import and DNA repair genes are likely important for survival and adaptation of D. deserti to its nutrient-poor, dry, and UV-exposed extreme environment.

  2. Fast Neutron Irradiation of the Highly Radioresistant Bacterium Deinococcus Radiodurans

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    Case, Diane Louise

    Fast neutron dose survival curves were generated for the bacterium Deinococcus radiodurans, which is renowned for its unusually high resistance to gamma, x-ray, and ultraviolet radiation, but for which fast neutron response was unknown. The fast neutrons were produced by the University of Massachusetts Lowell 5.5-MV, type CN Van de Graaff accelerator through the ^7Li(p,n)^7 Be reaction by bombarding a thick metallic lithium target with a 4-MeV proton beam. The bacteria were uniformly distributed on 150-mm agar plates and were exposed to the fast neutron beam under conditions of charged particle equilibrium. The plates were subdivided into concentric rings of increasing diameter from the center to the periphery of the plate, within which the average neutron dose was calculated as the product of the precisely known neutron fluence at the average radius of the ring and the neutron energy dependent kerma factor. The neutron fluence and dose ranged from approximately 3 times 1013 n cm^ {-2} to 1 times 1012 n cm^ {-2}, and 200 kilorad to 5 kilorad, respectively, from the center to the periphery of the plate. Percent survival for Deinococcus radiodurans as a function of fast neutron dose was derived from the ability of the irradiated cells to produce visible colonies within each ring compared to that of a nonirradiated control population. The bacterium Escherichia coli B/r (CSH) was irradiated under identical conditions for comparative purposes. The survival response of Deinococcus radiodurans as a result of cumulative fast neutron exposures was also investigated. The quantification of the ability of Deinococcus radiodurans to survive cellular insult from secondary charged particles, which are produced by fast neutron interactions in biological materials, will provide valuable information about damage and repair mechanisms under extreme cellular stress, and may provide new insight into the origin of this bacterium's unprecedented radiation resistance.

  3. High-quality genome sequence of the radioresistant bacterium Deinococcus ficus KS 0460

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    Matrosova, Vera Y.; Gaidamakova, Elena K.; Makarova, Kira S.; Grichenko, Olga; Klimenkova, Polina; Volpe, Robert P.; Tkavc, Rok; Ertem, G?zen; Conze, Isabel H.; Brambilla, Evelyne; Huntemann, Marcel; Clum, Alicia; Pillay, Manoj; Palaniappan, Krishnaveni; Varghese, Neha

    2017-01-01

    The genetic platforms of Deinococcus species remain the only systems in which massive ionizing radiation (IR)-induced genome damage can be investigated in vivo at exposures commensurate with cellular survival. We report the whole genome sequence of the extremely IR-resistant rod-shaped bacterium Deinococcus ficus KS 0460 and its phenotypic characterization. Deinococcus ficus KS 0460 has been studied since 1987, first under the name Deinobacter grandis, then Deinococcus grandis. The D. ficus K...

  4. Mechanisms of Stress Resistance and Gene Regulation in the Radioresistant Bacterium Deinococcus radiodurans.

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    Agapov, A A; Kulbachinskiy, A V

    2015-10-01

    The bacterium Deinococcus radiodurans reveals extraordinary resistance to ionizing radiation, oxidative stress, desiccation, and other damaging conditions. In this review, we consider the main molecular mechanisms underlying such resistance, including the action of specific DNA repair and antioxidation systems, and transcription regulation during the anti-stress response.

  5. High-quality genome sequence of the radioresistant bacterium Deinococcus ficus KS 0460.

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    Matrosova, Vera Y; Gaidamakova, Elena K; Makarova, Kira S; Grichenko, Olga; Klimenkova, Polina; Volpe, Robert P; Tkavc, Rok; Ertem, Gözen; Conze, Isabel H; Brambilla, Evelyne; Huntemann, Marcel; Clum, Alicia; Pillay, Manoj; Palaniappan, Krishnaveni; Varghese, Neha; Mikhailova, Natalia; Stamatis, Dimitrios; Reddy, Tbk; Daum, Chris; Shapiro, Nicole; Ivanova, Natalia; Kyrpides, Nikos; Woyke, Tanja; Daligault, Hajnalka; Davenport, Karen; Erkkila, Tracy; Goodwin, Lynne A; Gu, Wei; Munk, Christine; Teshima, Hazuki; Xu, Yan; Chain, Patrick; Woolbert, Michael; Gunde-Cimerman, Nina; Wolf, Yuri I; Grebenc, Tine; Gostinčar, Cene; Daly, Michael J

    2017-01-01

    The genetic platforms of Deinococcus species remain the only systems in which massive ionizing radiation (IR)-induced genome damage can be investigated in vivo at exposures commensurate with cellular survival. We report the whole genome sequence of the extremely IR-resistant rod-shaped bacterium Deinococcus ficus KS 0460 and its phenotypic characterization. Deinococcus ficus KS 0460 has been studied since 1987, first under the name Deinobacter grandis, then Deinococcus grandis. The D. ficus KS 0460 genome consists of a 4.019 Mbp sequence (69.7% GC content and 3894 predicted genes) divided into six genome partitions, five of which are confirmed to be circular. Circularity was determined manually by mate pair linkage. Approximately 76% of the predicted proteins contained identifiable Pfam domains and 72% were assigned to COGs. Of all D. ficus KS 0460 proteins, 79% and 70% had homologues in Deinococcus radiodurans ATCC BAA-816 and Deinococcus geothermalis DSM 11300, respectively. The most striking differences between D. ficus KS 0460 and D. radiodurans BAA-816 identified by the comparison of the KEGG pathways were as follows: (i) D. ficus lacks nine enzymes of purine degradation present in D. radiodurans, and (ii) D. ficus contains eight enzymes involved in nitrogen metabolism, including nitrate and nitrite reductases, that D. radiodurans lacks. Moreover, genes previously considered to be important to IR resistance are missing in D. ficus KS 0460, namely, for the Mn-transporter nramp, and proteins DdrF, DdrJ and DdrK, all of which are also missing in Deinococcus deserti. Otherwise, D. ficus KS 0460 exemplifies the Deinococcus lineage.

  6. Enzymes involved in DNA ligation and end-healing in the radioresistant bacterium Deinococcus radiodurans

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    Blasius, Melanie; Buob, Rebecca; Shevelev, Igor V; Hubscher, Ulrich

    2007-01-01

    Background Enzymes involved in DNA metabolic events of the highly radioresistant bacterium Deinococcus radiodurans are currently examined to understand the mechanisms that protect and repair the Deinococcus radiodurans genome after extremely high doses of γ-irradiation. Although several Deinococcus radiodurans DNA repair enzymes have been characterised, no biochemical data is available for DNA ligation and DNA endhealing enzymes of Deinococcus radiodurans so far. DNA ligases are necessary to seal broken DNA backbones during replication, repair and recombination. In addition, ionizing radiation frequently leaves DNA strand-breaks that are not feasible for ligation and thus require end-healing by a 5'-polynucleotide kinase or a 3'-phosphatase. We expect that DNA ligases and end-processing enzymes play an important role in Deinococcus radiodurans DNA strand-break repair. Results In this report, we describe the cloning and expression of a Deinococcus radiodurans DNA ligase in Escherichia coli. This enzyme efficiently catalyses DNA ligation in the presence of Mn(II) and NAD+ as cofactors and lysine 128 was found to be essential for its activity. We have also analysed a predicted second DNA ligase from Deinococcus radiodurans that is part of a putative DNA repair operon and shows sequence similarity to known ATP-dependent DNA ligases. We show that this enzyme possesses an adenylyltransferase activity using ATP, but is not functional as a DNA ligase by itself. Furthermore, we identified a 5'-polynucleotide kinase similar to human polynucleotide kinase that probably prepares DNA termini for subsequent ligation. Conclusion Deinococcus radiodurans contains a standard bacterial DNA ligase that uses NAD+ as a cofactor. Its enzymatic properties are similar to E. coli DNA ligase except for its preference for Mn(II) as a metal cofactor. The function of a putative second DNA ligase remains unclear, but its adenylyltransferase activity classifies it as a member of the

  7. Enzymes involved in DNA ligation and end-healing in the radioresistant bacterium Deinococcus radiodurans

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    Shevelev Igor V

    2007-08-01

    Full Text Available Abstract Background Enzymes involved in DNA metabolic events of the highly radioresistant bacterium Deinococcus radiodurans are currently examined to understand the mechanisms that protect and repair the Deinococcus radiodurans genome after extremely high doses of γ-irradiation. Although several Deinococcus radiodurans DNA repair enzymes have been characterised, no biochemical data is available for DNA ligation and DNA endhealing enzymes of Deinococcus radiodurans so far. DNA ligases are necessary to seal broken DNA backbones during replication, repair and recombination. In addition, ionizing radiation frequently leaves DNA strand-breaks that are not feasible for ligation and thus require end-healing by a 5'-polynucleotide kinase or a 3'-phosphatase. We expect that DNA ligases and end-processing enzymes play an important role in Deinococcus radiodurans DNA strand-break repair. Results In this report, we describe the cloning and expression of a Deinococcus radiodurans DNA ligase in Escherichia coli. This enzyme efficiently catalyses DNA ligation in the presence of Mn(II and NAD+ as cofactors and lysine 128 was found to be essential for its activity. We have also analysed a predicted second DNA ligase from Deinococcus radiodurans that is part of a putative DNA repair operon and shows sequence similarity to known ATP-dependent DNA ligases. We show that this enzyme possesses an adenylyltransferase activity using ATP, but is not functional as a DNA ligase by itself. Furthermore, we identified a 5'-polynucleotide kinase similar to human polynucleotide kinase that probably prepares DNA termini for subsequent ligation. Conclusion Deinococcus radiodurans contains a standard bacterial DNA ligase that uses NAD+ as a cofactor. Its enzymatic properties are similar to E. coli DNA ligase except for its preference for Mn(II as a metal cofactor. The function of a putative second DNA ligase remains unclear, but its adenylyltransferase activity classifies it as a

  8. Nucleoid organization in the radioresistant bacterium Deinococcus radiodurans.

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    Passot, Fanny Marie; Nguyen, Hong Ha; Dard-Dascot, Cloelia; Thermes, Claude; Servant, Pascale; Espéli, Olivier; Sommer, Suzanne

    2015-08-01

    Processes favoring the exceptional resistance to genotoxic stress of Deinococcus radiodurans are not yet completely characterized. It was postulated that its nucleoid and chromosome(s) organization could participate in the DNA double strand break repair process. Here, we investigated the organization of chromosome 1 by localization of three chromosomal loci including oriC, Ter and a locus located in its left arm. For this purpose, we used a ParB-parS system to visualize the position of the loci before and after exposure to γ-rays. By comparing the number of fluorescent foci with the number of copies of the studied loci present in the cells measured by quantitative polymerase chain reaction (qPCR), we demonstrated that the 4-10 copies of chromosome 1 per cell are dispersed within the nucleoid before irradiation, indicating that the chromosome copies are not prealigned. Chromosome segregation is progressive but not co-ordinated, allowing each locus to be paired with its sister during part of the cell cycle. After irradiation, the nucleoid organization is modified, involving a transient alignment of the loci in the late stage of DNA repair and a delay of segregation of the Ter locus. We discuss how these events can influence DNA double strand break repair. © 2015 John Wiley & Sons Ltd.

  9. A Mur Regulator Protein in the Extremophilic Bacterium Deinococcus radiodurans

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    Wang, Yunfei; Yan, Guoquan; Zhang, Qikun; Wang, Liangyan; Tian, Bing; Chen, Huan; Hua, Yuejin

    2014-01-01

    Ferric uptake regulator (Fur) is a transcriptional regulator that controls the expression of genes involved in the uptake of iron and manganese, as well as vital nutrients, and is essential for intracellular redox cycling. We identified a unique Fur homolog (DR0865) from Deinococcus radiodurans, which is known for its extreme resistance to radiation and oxidants. A dr0865 mutant (Mt-0865) showed a higher sensitivity to manganese stress, hydrogen peroxide, gamma irradiation and ultraviolet (UV) irradiation than the wild-type R1 strain. Cellular manganese (Mn) ion (Mn2+) analysis showed that Mn2+, copper (Cu2+), and ferric (Fe3+) ions accumulated significantly in the mutant, which suggests that the dr0865 gene is not only involved in the regulation of Mn2+ homeostasis, but also affects the uptake of other ions. In addition, transcriptome profiles under MnCl2 stress showed that the expression of many genes involved in Mn metabolism was significantly different in the wild-type R1 and DR0865 mutant (Mt-0865). Furthermore, we found that the dr0865 gene serves as a positive regulator of the manganese efflux pump gene mntE (dr1236), and as a negative regulator of Mn ABC transporter genes, such as dr2283, dr2284 and dr2523. Therefore, it plays an important role in maintaining the homoeostasis of intracellular Mn (II), and also other Mn2+, zinc (Zn2+) and Cu2+ ions. Based on its role in manganese homeostasis, DR0865 likely belongs to the Mur sub-family of Fur homolog. PMID:25243898

  10. A Mur regulator protein in the extremophilic bacterium Deinococcus radiodurans.

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    Amir Miraj Ul Hussain Shah

    Full Text Available Ferric uptake regulator (Fur is a transcriptional regulator that controls the expression of genes involved in the uptake of iron and manganese, as well as vital nutrients, and is essential for intracellular redox cycling. We identified a unique Fur homolog (DR0865 from Deinococcus radiodurans, which is known for its extreme resistance to radiation and oxidants. A dr0865 mutant (Mt-0865 showed a higher sensitivity to manganese stress, hydrogen peroxide, gamma irradiation and ultraviolet (UV irradiation than the wild-type R1 strain. Cellular manganese (Mn ion (Mn2+ analysis showed that Mn2+, copper (Cu2+, and ferric (Fe3+ ions accumulated significantly in the mutant, which suggests that the dr0865 gene is not only involved in the regulation of Mn2+ homeostasis, but also affects the uptake of other ions. In addition, transcriptome profiles under MnCl2 stress showed that the expression of many genes involved in Mn metabolism was significantly different in the wild-type R1 and DR0865 mutant (Mt-0865. Furthermore, we found that the dr0865 gene serves as a positive regulator of the manganese efflux pump gene mntE (dr1236, and as a negative regulator of Mn ABC transporter genes, such as dr2283, dr2284 and dr2523. Therefore, it plays an important role in maintaining the homoeostasis of intracellular Mn (II, and also other Mn2+, zinc (Zn2+ and Cu2+ ions. Based on its role in manganese homeostasis, DR0865 likely belongs to the Mur sub-family of Fur homolog.

  11. Efficient bioremediation of radioactive iodine using biogenic gold nanomaterial-containing radiation-resistant bacterium, Deinococcus radiodurans R1.

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    Choi, Mi Hee; Jeong, Sun-Wook; Shim, Ha Eun; Yun, Seong-Jae; Mushtaq, Sajid; Choi, Dae Seong; Jang, Beom-Su; Yang, Jung Eun; Choi, Yong Jun; Jeon, Jongho

    2017-04-04

    We herein report a new bioremediation method using a radiation-resistant bacterium. Biogenic gold nanomaterial-containing Deinococcus radiodurans R1 showed excellent capability for the removal of radioactive iodine (>99%) in several aqueous solutions. These observations demonstrated that our remediation system would be efficiently applied to the treatment of radioactive wastes.

  12. New features of the cell wall of the radio-resistant bacterium Deinococcus radiodurans.

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    Farci, Domenica; Bowler, Matthew W; Kirkpatrick, Joanna; McSweeney, Sean; Tramontano, Enzo; Piano, Dario

    2014-07-01

    We have analyzed the cell wall of the radio-resistant bacterium Deinococcus radiodurans. Unexpectedly, the bacterial envelope appears to be organized in different complexes of high molecular weight. Each complex is composed of several proteins, most of which are coded by genes of unknown function and the majority are constituents of the inner/outer membrane system. One of the most abundant complexes is constituted by the gene DR_0774. This protein is a type of secretin which is a known subunit of the homo-oligomeric channel that represents the main bulk of the type IV piliation family. Finally, a minor component of the pink envelope consists of several inner-membrane proteins. The implications of these findings are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. The death mechanism of the harmful algal bloom species Alexandrium tamarense induced by algicidal bacterium Deinococcus sp. Y35

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    Yi eLi

    2015-09-01

    Full Text Available Abstract: Harmful algal blooms (HABs cause a variety of deleterious effects on aquatic ecosystems, especially the toxic dinoflagellate Alexandrium tamarense, which poses a serious threat to marine economic and human health based on releasing paralytic shellfish poison into the environment. The algicidal bacterium Deinococcus sp. Y35 which can induce growth inhibition on A. tamarense was used to investigate the functional mechanism. The growth status, reactive oxygen species (ROS content, photosynthetic system and the nuclear system of algal cells were determined under algicidal activity. A culture of strain Y35 not only induced overproduction of ROS in algal cells within only 0.5 h of treatment, also decrease the total protein content as well as the response of the antioxidant enzyme. Meanwhile, lipid peroxidation was induced and cell membrane integrity was lost. Photosynthetic pigments including chlorophyll a and carotenoid decreased along with the photosynthetic efficiency being significantly inhibited. At the same time, photosynthesis-related gene expression showed down-regulation. More than, the destruction of cell nuclear structure and inhibition of proliferating cell nuclear antigen related gene expression were confirmed. The potential functional mechanism of the algicidal bacterium on A. tamarense was investigated and provided a novel viewpoint which could be used in HABs control.

  14. The death mechanism of the harmful algal bloom species Alexandrium tamarense induced by algicidal bacterium Deinococcus sp. Y35.

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    Li, Yi; Zhu, Hong; Lei, Xueqian; Zhang, Huajun; Cai, Guanjing; Chen, Zhangran; Fu, Lijun; Xu, Hong; Zheng, Tianling

    2015-01-01

    Harmful algal blooms (HABs) cause a variety of deleterious effects on aquatic ecosystems, especially the toxic dinoflagellate Alexandrium tamarense, which poses a serious threat to marine economic and human health based on releasing paralytic shellfish poison into the environment. The algicidal bacterium Deinococcus sp. Y35 which can induce growth inhibition on A. tamarense was used to investigate the functional mechanism. The growth status, reactive oxygen species (ROS) content, photosynthetic system and the nuclear system of algal cells were determined under algicidal activity. A culture of strain Y35 not only induced overproduction of ROS in algal cells within only 0.5 h of treatment, also decrease the total protein content as well as the response of the antioxidant enzyme. Meanwhile, lipid peroxidation was induced and cell membrane integrity was lost. Photosynthetic pigments including chlorophyll a and carotenoid decreased along with the photosynthetic efficiency being significantly inhibited. At the same time, photosynthesis-related gene expression showed down-regulation. More than, the destruction of cell nuclear structure and inhibition of proliferating cell nuclear antigen (PCNA) related gene expression were confirmed. The potential functional mechanism of the algicidal bacterium on A. tamarense was investigated and provided a novel viewpoint which could be used in HABs control.

  15. In vivo and in vitro characterization of DdrC, a DNA damage response protein in Deinococcus radiodurans bacterium.

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    Bouthier de la Tour, Claire; Mathieu, Martine; Meyer, Laura; Dupaigne, Pauline; Passot, Fanny; Servant, Pascale; Sommer, Suzanne; Le Cam, Eric; Confalonieri, Fabrice

    2017-01-01

    The bacterium Deinococcus radiodurans possesses a set of Deinococcus-specific genes highly induced after DNA damage. Among them, ddrC (dr0003) was recently re-annotated, found to be in the inverse orientation and called A2G07_00380. Here, we report the first in vivo and in vitro characterization of the corrected DdrC protein to better understand its function in irradiated cells. In vivo, the ΔddrC null mutant is sensitive to high doses of UV radiation and the ddrC deletion significantly increases UV-sensitivity of ΔuvrA or ΔuvsE mutant strains. We show that the expression of the DdrC protein is induced after γ-irradiation and is under the control of the regulators, DdrO and IrrE. DdrC is rapidly recruited into the nucleoid of the irradiated cells. In vitro, we show that DdrC is able to bind single- and double-stranded DNA with a preference for the single-stranded DNA but without sequence or shape specificity and protects DNA from various nuclease attacks. DdrC also condenses DNA and promotes circularization of linear DNA. Finally, we show that the purified protein exhibits a DNA strand annealing activity. Altogether, our results suggest that DdrC is a new DNA binding protein with pleiotropic activities. It might maintain the damaged DNA fragments end to end, thus limiting their dispersion and extensive degradation after exposure to ionizing radiation. DdrC might also be an accessory protein that participates in a single strand annealing pathway whose importance in DNA repair becomes apparent when DNA is heavily damaged.

  16. In vivo and in vitro characterization of DdrC, a DNA damage response protein in Deinococcus radiodurans bacterium.

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    Claire Bouthier de la Tour

    Full Text Available The bacterium Deinococcus radiodurans possesses a set of Deinococcus-specific genes highly induced after DNA damage. Among them, ddrC (dr0003 was recently re-annotated, found to be in the inverse orientation and called A2G07_00380. Here, we report the first in vivo and in vitro characterization of the corrected DdrC protein to better understand its function in irradiated cells. In vivo, the ΔddrC null mutant is sensitive to high doses of UV radiation and the ddrC deletion significantly increases UV-sensitivity of ΔuvrA or ΔuvsE mutant strains. We show that the expression of the DdrC protein is induced after γ-irradiation and is under the control of the regulators, DdrO and IrrE. DdrC is rapidly recruited into the nucleoid of the irradiated cells. In vitro, we show that DdrC is able to bind single- and double-stranded DNA with a preference for the single-stranded DNA but without sequence or shape specificity and protects DNA from various nuclease attacks. DdrC also condenses DNA and promotes circularization of linear DNA. Finally, we show that the purified protein exhibits a DNA strand annealing activity. Altogether, our results suggest that DdrC is a new DNA binding protein with pleiotropic activities. It might maintain the damaged DNA fragments end to end, thus limiting their dispersion and extensive degradation after exposure to ionizing radiation. DdrC might also be an accessory protein that participates in a single strand annealing pathway whose importance in DNA repair becomes apparent when DNA is heavily damaged.

  17. Background Mutational Features of the Radiation-Resistant Bacterium Deinococcus radiodurans.

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    Long, Hongan; Kucukyildirim, Sibel; Sung, Way; Williams, Emily; Lee, Heewook; Ackerman, Matthew; Doak, Thomas G; Tang, Haixu; Lynch, Michael

    2015-09-01

    Deinococcus bacteria are extremely resistant to radiation, oxidation, and desiccation. Resilience to these factors has been suggested to be due to enhanced damage prevention and repair mechanisms, as well as highly efficient antioxidant protection systems. Here, using mutation-accumulation experiments, we find that the GC-rich Deinococcus radiodurans has an overall background genomic mutation rate similar to that of E. coli, but differs in mutation spectrum, with the A/T to G/C mutation rate (based on a total count of 88 A:T → G:C transitions and 82 A:T → C:G transversions) per site per generation higher than that in the other direction (based on a total count of 157 G:C → A:T transitions and 33 G:C → T:A transversions). We propose that this unique spectrum is shaped mainly by the abundant uracil DNA glycosylases reducing G:C → A:T transitions, adenine methylation elevating A:T → C:G transversions, and absence of cytosine methylation decreasing G:C → A:T transitions. As opposed to the greater than 100× elevation of the mutation rate in MMR(-) (DNA Mismatch Repair deficient) strains of most other organisms, MMR(-) D. radiodurans only exhibits a 4-fold elevation, raising the possibility that other DNA repair mechanisms compensate for a relatively low-efficiency DNA MMR pathway. As D. radiodurans has plentiful insertion sequence (IS) elements in the genome and the activities of IS elements are rarely directly explored, we also estimated the insertion (transposition) rate of the IS elements to be 2.50 × 10(-3) per genome per generation in the wild-type strain; knocking out MMR did not elevate the IS element insertion rate in this organism. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Biosynthesis of gold nanoparticles by the extreme bacteriumDeinococcus radioduransand an evaluation of their antibacterial properties.

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    Li, Jiulong; Li, Qinghao; Ma, Xiaoqiong; Tian, Bing; Li, Tao; Yu, Jiangliu; Dai, Shang; Weng, Yulan; Hua, Yuejin

    Deinococcus radiodurans is an extreme bacterium known for its high resistance to stresses including radiation and oxidants. The ability of D. radiodurans to reduce Au(III) and biosynthesize gold nanoparticles (AuNPs) was investigated in aqueous solution by ultraviolet and visible (UV/Vis) absorption spectroscopy, electron microscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). D. radiodurans efficiently synthesized AuNPs from 1 mM Au(III) solution in 8 h. The AuNPs were of spherical, triangular and irregular shapes with an average size of 43.75 nm and a polydispersity index of 0.23 as measured by DLS. AuNPs were distributed in the cell envelope, across the cytosol and in the extracellular space. XRD analysis confirmed the crystallite nature of the AuNPs from the cell supernatant. Data from the FTIR and XPS showed that upon binding to proteins or compounds through interactions with carboxyl, amine, phospho and hydroxyl groups, Au(III) may be reduced to Au(I), and further reduced to Au(0) with the capping groups to stabilize the AuNPs. Biosynthesis of AuNPs was optimized with respect to the initial concentration of gold salt, bacterial growth period, solution pH and temperature. The purified AuNPs exhibited significant antibacterial activity against both Gram-negative ( Escherichia coli ) and Gram-positive ( Staphylococcus aureus ) bacteria by damaging their cytoplasmic membrane. Therefore, the extreme bacterium D. radiodurans can be used as a novel bacterial candidate for efficient biosynthesis of AuNPs, which exhibited potential in biomedical application as an antibacterial agent.

  19. Thermostable lipases from extremely radioresistant bacterium Deinococcus radiodurans: cloning, expression, and biochemical characterization.

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    Shao, Hua; Xu, Li; Yan, Yunjun

    2014-09-01

    A search for lipases was conducted in the radiophile of Deinococcus radiodurans R1. Four putative lipase genes, encoding DR0334, DR2078, DR1485, and DR2522, were cloned and expressed in Escherichia coli. The recombinant enzymes were subsequently purified and characterized. The results showed DR0334 and DR2078 had the ability to hydrolyze long-chain length p-nitrophenyl esters (C12-C16), while DR1485 and DR2522 hydrolyzed short- and medium-chain length p-nitrophenyl esters (C2-C10). DR0334, DR1485, DR2078, and DR2522 showed optimum pH at 8.5, and optimum temperature at 40, 50, 60, and 60 °C, respectively. DR0334 almost lost its whole activity after 60 min pretreatment at 60 °C, while DR1485, DR2078, and DR2522 retained more than 70% of their original activities after 6 h incubation at 80 °C. The activities of DR2078, DR1485, and DR2522 were enhanced by Mg(2+) , Ba(2+) , and Mn(2+) , but strongly inhibited by EDTA. Nevertheless, DR2078, DR1485, and DR2522 showed moderate stability in organic solvents and detergents. Phylogenetic analysis revealed that DR0334 and DR2078, respectively belong to family IV and family IX, while each of DR1485 and DR2522 forms a new separate branch. The unique properties of DR2078, DR1485, and DR2522, thermostability and organic solvent tolerance, make them useful in industrial applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. The study of the extreme radiation tolerance mechanisms of the bacterium Deinococcus deserti by a functional genomics approach; Etude des mecanismes de l'extreme tolerance aux radiations de la bacterie Deinococcus deserti par une approche de genomique fonctionnelle

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    Dulermo, R.

    2009-12-15

    The genome of Deinococcus deserti, a highly radiation-tolerant bacterium, was analyzed and compared to those of D. radiodurans and D. geothermalis. About 230 proteins are specifically conserved in these 3 species, including IrrE, a regulator protein essential for radio tolerance. D.deserti has several supplementary DNA repair genes, like imuY and dnaE2 (trans-lesion DNA polymerases). Moreover, D. deserti has 3 recA that code for 2 different RecA proteins (RecAC et RecAP). To study these genes, genetic tools were developed for D. deserti. Different results suggest that IrrE, required for the induction of several genes after irradiation, has peptidase activity. The 2 RecA proteins are functional for DNA repair. D. deserti is mutable by UV, which requires ImuY, DnaE2 and RecAC, but not RecAP. (author)

  1. Biosynthesis of gold nanoparticles by the extreme bacterium Deinococcus radiodurans and an evaluation of their antibacterial properties

    OpenAIRE

    Li J; Li Q.; Ma X.; Tian B; Li T; Yu J; Dai S.; Weng Y.; Hua Y

    2016-01-01

    Jiulong Li,1,* Qinghao Li,1,* Xiaoqiong Ma,2,* Bing Tian,1 Tao Li,1 Jiangliu Yu,1 Shang Dai,1 Yulan Weng,1 Yuejin Hua1 1Key Laboratory for Nuclear-Agricultural Sciences of Chinese Ministry of Agriculture and Zhejiang Province, Institute of Nuclear-Agricultural Sciences, Zhejiang University, 2Central Laboratory, The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China *These authors contributed equally to this work Abstract: Deinococcus radiodurans is a...

  2. DqsIR quorum sensing-mediated gene regulation of the extremophilic bacterium Deinococcus radiodurans in response to oxidative stress.

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    Lin, Lin; Dai, Shang; Tian, Bing; Li, Tao; Yu, Jiangliu; Liu, Chengzhi; Wang, Liangyan; Xu, Hong; Zhao, Ye; Hua, Yuejin

    2016-05-01

    Here, we show that AHLs can be employed by Deinococcus radiodurans, which belongs to the unique phylum Deinococcus-Thermus and is known for its cellular resistance to environmental stresses. An AHL-mediated quorum-sensing system (DqsI/DqsR) was identified in D. radiodurans. We found that under non-stress conditions, the AHL level was "shielded" by quorum quenching enzymes, whereas AHLs accumulated when D. radiodurans was exposed to oxidative stress. Upon exposure to H2 O2 , AHL synthetic enzymes (DqsI) were immediately induced, while the expression of quorum-quenching enzymes began to increase approximately 30 min after exposure to H2 O2 , as shown by time-course analyses of gene expression. Both dqsI mutant (DMDqsI) and dqsR mutant (MDqsR) were more sensitive to oxidative stress compared with the wild-type strain. Exogenous AHLs (5 μM) could completely restore the survival fraction of DMDqsI under oxidative stress. RNA-seq analysis showed that a number of genes involved in stress-response, cellular cleansing, and DNA repair had altered transcriptional levels in MDqsR. The DqsR, acting as a regulator of quorum sensing, controls gene expression along with AHLs. Hence, the DqsIR-mediated quorum sensing that mediates gene regulation is an adaptive strategy for D. radiodurans in response to oxidative stresses and is conserved in the extremophilic Deinococcus bacteria. © 2016 John Wiley & Sons Ltd.

  3. A PerR-like protein involved in response to oxidative stress in the extreme bacterium Deinococcus radiodurans.

    Science.gov (United States)

    Liu, Chengzhi; Wang, Liangyan; Li, Tao; Lin, Lin; Dai, Shang; Tian, Bing; Hua, Yuejin

    2014-07-18

    Response and defense systems against reactive oxygen species (ROS) contribute to the remarkable resistance of Deinococcus radiodurans to oxidative stress induced by oxidants or radiation. However, mechanisms involved in ROS response and defense systems of D. radiodurans are not well understood. Fur family proteins are important in ROS response. Only a single Fur homolog is predicted by sequence similarity in the current D. radiodurans genome database. Our bioinformatics analysis demonstrated an additional guanine nucleotide in the genome of D. radiodurans that is not in the database, leading to the discovery of another Fur homolog DrPerR. Gene disruption mutant of DrPerR showed enhanced resistance to hydrogen peroxide (H2O2) and increased catalase activity in cell extracts. Real-time PCR results indicated that DrPerR functions as a repressor of the catalase gene katE. Meanwhile, derepression of dps (DNA-binding proteins from starved cells) gene under H2O2 stress by DrPerR point to its regulatory role in metal ions hemostasis. Thus, DrPerR might function as a Fur homolog protein which is involved in ROS response and defense. These results help clarify the complicated regulatory network that responds to ROS stress in D. radiodurans. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Genome sequence and transcriptome analysis of the radioresistant bacterium Deinococcus gobiensis: insights into the extreme environmental adaptations.

    Directory of Open Access Journals (Sweden)

    Menglong Yuan

    Full Text Available The desert is an excellent model for studying evolution under extreme environments. We present here the complete genome and ultraviolet (UV radiation-induced transcriptome of Deinococcus gobiensis I-0, which was isolated from the cold Gobi desert and shows higher tolerance to gamma radiation and UV light than all other known microorganisms. Nearly half of the genes in the genome encode proteins of unknown function, suggesting that the extreme resistance phenotype may be attributed to unknown genes and pathways. D. gobiensis also contains a surprisingly large number of horizontally acquired genes and predicted mobile elements of different classes, which is indicative of adaptation to extreme environments through genomic plasticity. High-resolution RNA-Seq transcriptome analyses indicated that 30 regulatory proteins, including several well-known regulators and uncharacterized protein kinases, and 13 noncoding RNAs were induced immediately after UV irradiation. Particularly interesting is the UV irradiation induction of the phrB and recB genes involved in photoreactivation and recombinational repair, respectively. These proteins likely include key players in the immediate global transcriptional response to UV irradiation. Our results help to explain the exceptional ability of D. gobiensis to withstand environmental extremes of the Gobi desert, and highlight the metabolic features of this organism that have biotechnological potential.

  5. A PerR-like protein involved in response to oxidative stress in the extreme bacterium Deinococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chengzhi; Wang, Liangyan; Li, Tao; Lin, Lin; Dai, Shang; Tian, Bing, E-mail: tianbing@zju.edu.cn; Hua, Yuejin, E-mail: yjhua@zju.edu.cn

    2014-07-18

    Highlights: • We report a novel PerR-like protein of Fur family in D. radiodurans that is not annotated in the current database. • drperR responses to H{sub 2}O{sub 2} and functions as a negative regulator of katE and dps. • We provided implications on how to utilize sequenced genome data and the importance of genome data mining. • This study adds knowledge to complicated regulatory network that responds to ROS stress in D. radiodurans. - Abstract: Response and defense systems against reactive oxygen species (ROS) contribute to the remarkable resistance of Deinococcus radiodurans to oxidative stress induced by oxidants or radiation. However, mechanisms involved in ROS response and defense systems of D. radiodurans are not well understood. Fur family proteins are important in ROS response. Only a single Fur homolog is predicted by sequence similarity in the current D. radiodurans genome database. Our bioinformatics analysis demonstrated an additional guanine nucleotide in the genome of D. radiodurans that is not in the database, leading to the discovery of another Fur homolog DrPerR. Gene disruption mutant of DrPerR showed enhanced resistance to hydrogen peroxide (H{sub 2}O{sub 2}) and increased catalase activity in cell extracts. Real-time PCR results indicated that DrPerR functions as a repressor of the catalase gene katE. Meanwhile, derepression of dps (DNA-binding proteins from starved cells) gene under H{sub 2}O{sub 2} stress by DrPerR point to its regulatory role in metal ions hemostasis. Thus, DrPerR might function as a Fur homolog protein which is involved in ROS response and defense. These results help clarify the complicated regulatory network that responds to ROS stress in D. radiodurans.

  6. Single Strand Annealing Plays a Major Role in RecA-Independent Recombination between Repeated Sequences in the Radioresistant Deinococcus radiodurans Bacterium

    Science.gov (United States)

    Ithurbide, Solenne; Bentchikou, Esma; Coste, Geneviève; Bost, Bruno; Servant, Pascale; Sommer, Suzanne

    2015-01-01

    The bacterium Deinococcus radiodurans is one of the most radioresistant organisms known. It is able to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Our work aims to highlight the genes involved in recombination between 438 bp direct repeats separated by intervening sequences of various lengths ranging from 1,479 bp to 10,500 bp to restore a functional tetA gene in the presence or absence of radiation-induced DNA double strand breaks. The frequency of spontaneous deletion events between the chromosomal direct repeats were the same in recA+ and in ΔrecA, ΔrecF, and ΔrecO bacteria, whereas recombination between chromosomal and plasmid DNA was shown to be strictly dependent on the RecA and RecF proteins. The presence of mutations in one of the repeated sequence reduced, in a MutS-dependent manner, the frequency of the deletion events. The distance between the repeats did not influence the frequencies of deletion events in recA + as well in ΔrecA bacteria. The absence of the UvrD protein stimulated the recombination between the direct repeats whereas the absence of the DdrB protein, previously shown to be involved in DNA double strand break repair through a single strand annealing (SSA) pathway, strongly reduces the frequency of RecA- (and RecO-) independent deletions events. The absence of the DdrB protein also increased the lethal sectoring of cells devoid of RecA or RecO protein. γ-irradiation of recA + cells increased about 10-fold the frequencies of the deletion events, but at a lesser extend in cells devoid of the DdrB protein. Altogether, our results suggest a major role of single strand annealing in DNA repeat deletion events in bacteria devoid of the RecA protein, and also in recA + bacteria exposed to ionizing radiation. PMID:26517555

  7. Single Strand Annealing Plays a Major Role in RecA-Independent Recombination between Repeated Sequences in the Radioresistant Deinococcus radiodurans Bacterium.

    Directory of Open Access Journals (Sweden)

    Solenne Ithurbide

    2015-10-01

    Full Text Available The bacterium Deinococcus radiodurans is one of the most radioresistant organisms known. It is able to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Our work aims to highlight the genes involved in recombination between 438 bp direct repeats separated by intervening sequences of various lengths ranging from 1,479 bp to 10,500 bp to restore a functional tetA gene in the presence or absence of radiation-induced DNA double strand breaks. The frequency of spontaneous deletion events between the chromosomal direct repeats were the same in recA+ and in ΔrecA, ΔrecF, and ΔrecO bacteria, whereas recombination between chromosomal and plasmid DNA was shown to be strictly dependent on the RecA and RecF proteins. The presence of mutations in one of the repeated sequence reduced, in a MutS-dependent manner, the frequency of the deletion events. The distance between the repeats did not influence the frequencies of deletion events in recA+ as well in ΔrecA bacteria. The absence of the UvrD protein stimulated the recombination between the direct repeats whereas the absence of the DdrB protein, previously shown to be involved in DNA double strand break repair through a single strand annealing (SSA pathway, strongly reduces the frequency of RecA- (and RecO- independent deletions events. The absence of the DdrB protein also increased the lethal sectoring of cells devoid of RecA or RecO protein. γ-irradiation of recA+ cells increased about 10-fold the frequencies of the deletion events, but at a lesser extend in cells devoid of the DdrB protein. Altogether, our results suggest a major role of single strand annealing in DNA repeat deletion events in bacteria devoid of the RecA protein, and also in recA+ bacteria exposed to ionizing radiation.

  8. Improved Complete Genome Sequence of the Extremely Radioresistant Bacterium Deinococcus radiodurans R1 Obtained Using PacBio Single-Molecule Sequencing

    OpenAIRE

    Hua, Xiaoting; Hua, Yuejin

    2016-01-01

    The genome sequence of Deinococcus radiodurans R1 was published in 1999. We resequenced D.?radiodurans R1 using PacBio and compared the sequence with the published one. Large insertions and single nucleotide polymorphisms (SNPs) were observed among the genome sequences. A more accurate genome sequence will be helpful to studies of D.?radiodurans.

  9. Improved Complete Genome Sequence of the Extremely Radioresistant Bacterium Deinococcus radiodurans R1 Obtained Using PacBio Single-Molecule Sequencing.

    Science.gov (United States)

    Hua, Xiaoting; Hua, Yuejin

    2016-09-01

    The genome sequence of Deinococcus radiodurans R1 was published in 1999. We resequenced D. radiodurans R1 using PacBio and compared the sequence with the published one. Large insertions and single nucleotide polymorphisms (SNPs) were observed among the genome sequences. A more accurate genome sequence will be helpful to studies of D. radiodurans. Copyright © 2016 Hua and Hua.

  10. DdrO is an essential protein that regulates the radiation desiccation response and the apoptotic-like cell death in the radioresistant Deinococcus radiodurans bacterium.

    Science.gov (United States)

    Devigne, Alice; Ithurbide, Solenne; Bouthier de la Tour, Claire; Passot, Fanny; Mathieu, Martine; Sommer, Suzanne; Servant, Pascale

    2015-06-01

    Deinococcus radiodurans is known for its extreme radioresistance. Comparative genomics identified a radiation-desiccation response (RDR) regulon comprising genes that are highly induced after DNA damage and containing a conserved motif (RDRM) upstream of their coding region. We demonstrated that the RDRM sequence is involved in cis-regulation of the RDR gene ddrB in vivo. Using a transposon mutagenesis approach, we showed that, in addition to ddrO encoding a predicted RDR repressor and irrE encoding a positive regulator recently shown to cleave DdrO in Deinococcus deserti, two genes encoding α-keto-glutarate dehydrogenase subunits are involved in ddrB regulation. In wild-type cells, the DdrO cell concentration decreased transiently in an IrrE-dependent manner at early times after irradiation. Using a conditional gene inactivation system, we showed that DdrO depletion enhanced expression of three RDR proteins, consistent with the hypothesis that DdrO acts as a repressor of the RDR regulon. DdrO-depleted cells loose viability and showed morphological changes evocative of an apoptotic-like response, including membrane blebbing, defects in cell division and DNA fragmentation. We propose that DNA repair and apoptotic-like death might be two responses mediated by the same regulators, IrrE and DdrO, but differently activated depending on the persistence of IrrE-dependent DdrO cleavage. © 2015 John Wiley & Sons Ltd.

  11. Promoter cloning in the radioresistant bacteruim Deinococcus radiodurans

    NARCIS (Netherlands)

    Meima, R.B.; Rothfuss, H.M.; Gewin, L.; Lidstrom, M.E.

    2001-01-01

    Deinococcus radiodurans is a highly radiation-resistant bacterium that is classed in a major subbranch of the bacterial domain. Since very little is known about gene expression in this bacterium, an initial study of promoters was undertaken. In order to isolate promoters and study promoter function,

  12. FtsZDr, a tubulin homologue in radioresistant bacterium Deinococcus radiodurans is characterized as a GTPase exhibiting polymerization/depolymerization dynamics in vitro and FtsZ ring formation in vivo.

    Science.gov (United States)

    Modi, Kruti Mehta; Tewari, Raghvendra; Misra, Hari Sharan

    2014-05-01

    The GTPase-dependent polymerization/depolymerization dynamics of FtsZ regulate bacterial cell division in vivo. Deinococcus radiodurans is better known for its extraordinary radioresistance and therefore, the characterization of FtsZ of this bacterium (FtsZDr) would be required to understand the mechanisms underlying regulation of cell division in response to DNA damage. Recombinant FtsZDr bound to GTP and showed GTPase activity. It produced bundles of protofilaments in the presence of either GTP or Mg2+ ions. But the formation of the higher size ordered structures required both GTP and Mg2+ in vitro. It showed polymerization/depolymerization dynamics as a function of GTP and Mg2+. Interestingly, ATP interacted with FtsZDr and stimulated its GTPase activity by ∼2-fold possibly by increasing both substrate affinity and rate of reaction. FtsZDr-GFP expressing in D. radiodurans produced typical Z ring perpendicular to the plane of first cell division. These results suggested that FtsZDr is a GTPase in vitro and produces typical Z ring at the mid cell position in D. radiodurans. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Intrinsically disordered regions may lower the hydration free energy in proteins: a case study of nudix hydrolase in the bacterium Deinococcus radiodurans.

    Directory of Open Access Journals (Sweden)

    Omar Awile

    Full Text Available The proteome of the radiation- and desiccation-resistant bacterium D. radiodurans features a group of proteins that contain significant intrinsically disordered regions that are not present in non-extremophile homologues. Interestingly, this group includes a number of housekeeping and repair proteins such as DNA polymerase III, nudix hydrolase and rotamase. Here, we focus on a member of the nudix hydrolase family from D. radiodurans possessing low-complexity N- and C-terminal tails, which exhibit sequence signatures of intrinsic disorder and have unknown function. The enzyme catalyzes the hydrolysis of oxidatively damaged and mutagenic nucleotides, and it is thought to play an important role in D. radiodurans during the recovery phase after exposure to ionizing radiation or desiccation. We use molecular dynamics simulations to study the dynamics of the protein, and study its hydration free energy using the GB/SA formalism. We show that the presence of disordered tails significantly decreases the hydration free energy of the whole protein. We hypothesize that the tails increase the chances of the protein to be located in the remaining water patches in the desiccated cell, where it is protected from the desiccation effects and can function normally. We extrapolate this to other intrinsically disordered regions in proteins, and propose a novel function for them: intrinsically disordered regions increase the "surface-properties" of the folded domains they are attached to, making them on the whole more hydrophilic and potentially influencing, in this way, their localization and cellular activity.

  14. Distribution of ddr (DNA damage response) genes among species of deinococcus

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sang Yong; Jung, Sun Wook; Joe, Min Ho; Kim, Dong Ho [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2010-09-15

    The bacterium Deinococcus radiodurans is one of the most resistant organisms to the effects of ionizing radiation and other DNA-damaging agents. In this study, distributions of 10 ddr (DNA damage response) genes were investigated in 8 species of Deinocossus by polymerase chain reaction (PCR). We have compared the sequences of ddr genes of D. radiodurans, D. geothermalis and D. deserti, and selected primers which are suitable for the detection of ddr in different species of Deinococcus. A sequence homology search and PCR assay showed that ddrO, which encodes a global regulator of the radiation-desiccation response, was most well conserved in the Deinococcus lineage.

  15. in Deinococcus radiodurans

    African Journals Online (AJOL)

    STORAGESEVER

    2010-05-10

    May 10, 2010 ... Deinococcus radiodurans is best known for its extraordinary radiation resistance. Manganese(II) ions can protect proteins from being damaged by super radicals, which is supposed to be the main mechanism through which D. radiodurans has the strong radiation resistance. But the detailed molecular and ...

  16. Thioredoxin System from Deinococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Obiero, Josiah; Pittet, Vanessa; Bonderoff, Sara A.; Sanders, David A.R. (Saskatchewan)

    2010-05-03

    This paper describes the cloning, purification, and characterization of thioredoxin (Trx) and thioredoxin reductase (TrxR) and the structure determination of TrxR from the ionizing radiation-tolerant bacterium Deinococcus radiodurans strain R1. The genes from D. radiodurans encoding Trx and TrxR were amplified by PCR, inserted into a pET expression vector, and overexpressed in Escherichia coli. The overexpressed proteins were purified by metal affinity chromatography, and their activity was demonstrated using well-established assays of insulin precipitation (for Trx), 5,5{prime}-dithiobis(2-nitrobenzoic acid) (DTNB) reduction, and insulin reduction (for TrxR). In addition, the crystal structure of oxidized TrxR was determined at 1.9-{angstrom} resolution. The overall structure was found to be very similar to that of E. coli TrxR and homodimeric with both NADPH- and flavin adenine dinucleotide (FAD)-binding domains containing variants of the canonical nucleotide binding fold, the Rossmann fold. The K{sub m} (5.7 {micro}M) of D. radiodurans TrxR for D. radiodurans Trx was determined and is about twofold higher than that of the E. coli thioredoxin system. However, D. radiodurans TrxR has a much lower affinity for E. coli Trx (K{sub m}, 44.4 {micro}M). Subtle differences in the surface charge and shape of the Trx binding site on TrxR may account for the differences in recognition. Because it has been suggested that TrxR from D. radiodurans may have dual cofactor specificity (can utilize both NADH and NADPH), D. radiodurans TrxR was tested for its ability to utilize NADH as well. Our results show that D. radiodurans TrxR can utilize only NADPH for activity.

  17. Major soluble proteome changes in Deinococcus deserti over the earliest stages following gamma-ray irradiation

    Directory of Open Access Journals (Sweden)

    Dedieu Alain

    2013-01-01

    Full Text Available Abstract Background Deinococcus deserti VCD115 has been isolated from Sahara surface sand. This radiotolerant bacterium represents an experimental model of choice to understand adaptation to harsh conditions encountered in hot arid deserts. We analysed the soluble proteome dynamics in this environmentally relevant model after exposure to 3 kGy gamma radiation, a non-lethal dose that generates massive DNA damages. For this, cells were harvested at different time lapses after irradiation and their soluble proteome contents have been analysed by 2-DE and mass spectrometry. Results In the first stage of the time course we observed accumulation of DNA damage response protein DdrB (that shows the highest fold change ~11, SSB, and two different RecA proteins (RecAP and RecAC. Induction of DNA repair protein PprA, DNA damage response protein DdrD and the two gyrase subunits (GyrA and GyrB was also detected. A response regulator of the SarP family, a type II site-specific deoxyribonuclease and a putative N-acetyltransferase are three new proteins found to be induced. In a more delayed stage, we observed accumulation of several proteins related to central metabolism and protein turn-over, as well as helicase UvrD and novel forms of both gyrase subunits differing in terms of isoelectric point and molecular weight. Conclusions Post-translational modifications of GyrA (N-terminal methionine removal and acetylation have been evidenced and their significance discussed. We found that the Deide_02842 restriction enzyme, which is specifically found in D. deserti, is a new potential member of the radiation/desiccation response regulon, highlighting the specificities of D. deserti compared to the D. radiodurans model.

  18. Effects of heavy ions on inactivation and DNA double strand breaks in Deinococcus radiodurans R1

    Science.gov (United States)

    Zimmermann, H.; Schäfer, M.; Schmitz, C.; Bücker, H.

    1994-10-01

    Inactivation and double strand break (dsb) induction after heavy ion irradiation were studied in stationary phase cells of the highly radiation resistant bacterium Deinococcus radiodurans R1. There is evidence that the radiation sensitivity of this bacterium is nearly independent on energy in the range of up to 15 MeV/u for lighter ions (Ar). The responses to dsb induction for charged particles show direct relationship between increasing radiation dose and residual intact DNA.

  19. Effects of heavy ions on inactivation and DNA double strand breaks in Deinococcus radiodurans R1.

    Science.gov (United States)

    Zimmermann, H; Schafer, M; Schmitz, C; Bucker, H

    1994-10-01

    Inactivation and double strand break (dsb) induction after heavy ion irradiation were studied in stationary phase cells of the highly radiation resistant bacterium Deinococcus radiodurans R1. There is evidence that the radiation sensitivity of this bacterium is nearly independent on energy in the range of up to 15 MeV/u for lighter ions (Ar). The responses to dsb induction for charged particles show direct relationship between increasing radiation dose and residual intact DNA.

  20. Biology of Extreme Radiation Resistance: The Way of Deinococcus radiodurans

    Science.gov (United States)

    Krisko, Anita; Radman, Miroslav

    2013-01-01

    The bacterium Deinococcus radiodurans is a champion of extreme radiation resistance that is accounted for by a highly efficient protection against proteome, but not genome, damage. A well-protected functional proteome ensures cell recovery from extensive radiation damage to other cellular constituents by molecular repair and turnover processes, including an efficient repair of disintegrated DNA. Therefore, cell death correlates with radiation-induced protein damage, rather than DNA damage, in both robust and standard species. From the reviewed biology of resistance to radiation and other sources of oxidative damage, we conclude that the impact of protein damage on the maintenance of life has been largely underestimated in biology and medicine. PMID:23818498

  1. Sahara en mouvement

    OpenAIRE

    Casajus, Dominique

    2013-01-01

    On peut dire du Sahara ce que Fernand Braudel disait naguère de la Méditerranée : lui assigner des bornages est une tâche malaisée. Des géographes s’y sont cependant essayés, et leurs tentatives participent de ce qu’on peut appeler l’« invention » du Sahara. La présente introduction évoque quelques figures marquantes de cette invention (Léon l’Africain, Eugène Daumas, Émile Carette, Henri Duveyrier, Robert Capot-Rey…) puis présente brièvement les diverses contributions du dossier, en les repl...

  2. "Deinococcus radiodurans" - a model organism for life under Martian conditions

    Science.gov (United States)

    Rettberg, P.; de La Vega, U.; Horneck, G.

    2004-03-01

    Deinococcus radiodurans, a gram positive bacterium whose ability to survive extremely high damage to its DNA which is for example induced by genotoxic chemicals, ionizing radiation, UV radiation or desiccation is still not completely understood. Because of its radiation and desiccation resistance, this extremophile is a prime candidate for possibly surviving environmental conditions as they occur on Mars and during a hypothetical interplanetary space travel. So far just minor work has been done on the damaging effects of UV radiation, especially polychromatic UV radiation in the UVB and UVA range, and desiccation/vacuum exposure, which is known to induce DNA damages similar to radiation. Therefore, we started to further investigate the radiation resistance and the repair mechanisms of Deinococcus radiodurans, concentrating on the effect of polychromatic UV radiation and desiccation in the wild type strain and ionizing radiation and UV radiation sensitive mutants. The results of this ongoing project will be of great interest to questions concerning planetary protection, spacecraft disinfecting measures and the search for life on other earth-like planets in general.

  3. Oxidative Stress Resistance in Deinococcus radiodurans†

    Science.gov (United States)

    Slade, Dea; Radman, Miroslav

    2011-01-01

    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. PMID:21372322

  4. Oxidative stress resistance in Deinococcus radiodurans.

    Science.gov (United States)

    Slade, Dea; Radman, Miroslav

    2011-03-01

    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.

  5. Deinococcus radiodurans bacteria of extreme;Deinococcus radiodurans bacterie de l'extreme

    Energy Technology Data Exchange (ETDEWEB)

    Pellay, F.X.; Matic, I.

    2010-05-15

    Extreme levels of radiation, desiccation, oxidative stress, Deinococcus radiodurans can survive in environments that degrade or damage DNA, proteins and virtually all macromolecules of life. To survive these conditions, Deinococcus have developed systems of protection, repair and recycling of exceptional efficiency. (N.C.)

  6. PprM, a Cold Shock Domain-Containing Protein from Deinococcus radiodurans, Confers Oxidative Stress Tolerance to Escherichia coli

    OpenAIRE

    Park, Sun-Ha; Singh, Harinder; Appukuttan, Deepti; Jeong, Sunwook; Choi, Yong Jun; Jung, Jong-Hyun; Narumi, Issay; Lim, Sangyong

    2017-01-01

    Escherichia coli is a representative microorganism that is frequently used for industrial biotechnology; thus its cellular robustness should be enhanced for the widespread application of E. coli in biotechnology. Stress response genes from the extremely radioresistant bacterium Deinococcus radiodurans have been used to enhance the stress tolerance of E. coli. In the present study, we introduced the cold shock domain-containing protein PprM from D. radiodurans into E. coli and observed that th...

  7. [Malaria in Algerian Sahara].

    Science.gov (United States)

    Hammadi, D; Boubidi, S C; Chaib, S E; Saber, A; Khechache, Y; Gasmi, M; Harrat, Z

    2009-08-01

    Thanks to the malaria eradication campaign launched in Algeria in 1968, the number of malaria cases fell down significantly from 95,424 cases in 1960 to 30 cases in 1978. At that time the northern part of the country was declared free of Plasmodium falciparum. Only few cases belonging to P. vivax persisted in residual foci in the middle part of the country. In the beginning of the eighties, the south of the country was marked by an increase of imported malaria cases. The resurgence of the disease in the oases coincided with the opening of the Trans-Saharan road and the booming trade with the neighbouring southern countries. Several authors insisted on the risk of introduction of malaria or its exotic potential vectors in Algeria via this new road. Now, the totality of malaria autochthonous cases in Algeria are located in the south of the country where 300 cases were declared during the period (1980-2007). The recent outbreak recorded in 2007 at the borders with Mall and the introduction of Anopheles gambiae into the Algerian territory show the vulnerability of this area to malaria which is probably emphasized by the local environmental changes. The authors assess the evolution of malaria in the Sahara region and draw up the distribution of the anopheles in this area.

  8. Extracellular peptidases from Deinococcus radiodurans.

    Science.gov (United States)

    Dalmaso, Gabriel Z L; Lage, Claudia A S; Mazotto, Ana Maria; Dias, Edilma Paraguai de Souza; Caldas, Lucio Ayres; Ferreira, Davis; Vermelho, Alane B

    2015-09-01

    The extremophile Deinococcus radiodurans wild type R1 produces peptidases (metallo- and serine-) in TGY medium and in the media supplemented with human hair (HMY) and chicken feathers (FMY). Enzymatic screening on agar plates revealed peptidase activity. In TGY medium metallopeptidases were detected corresponding to a molecular mass range of 300-85 kDa (gelatinases); 280-130 (caseinases) and a 300 and a 170 kDa (keratinases); and a gelatinolytic serine peptidase (75 kDa). In HMY medium after 144 h, D. radiodurans produced keratinase (290 U/ml), gelatinase (619 U/ml) and sulfite (26 µg/ml). TGY medium produced higher proteolytic activity: 950 U/ml of gelatinolytic (24 h); 470 U/ml of keratinolytic (24 h) and 110 U/ml of caseinolytic (72 h). In the FMY medium, we found gelatinolytic (317 U/ml), keratinolytic (43 U/ml) and caseinolytic (85 U/ml) activities. The sulfite had a maximum release at 48 h (8.1 µg/ml). Enzymography analysis revealed that the keratinases degraded keratin after 24 h of reaction. The addition of sodium sulfite (1.0 %) improved the keratin degradation. Environmental Scanning Electron microscopy revealed alterations such as damage and holes in the hair fiber cuticle after D. radiodurans growth. This work presents for the first time D. radiodurans as a new keratinolytic microorganism.

  9. Design and Construction of Deinococcus Radiodurans for Biodegradation of Organic Toxins at Radioactive DOE Waste Sites

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Daly; Lawrence P. Wackett; James K. Fredrickson

    2001-04-22

    Seventy million cubic meters of ground and three trillion liters of groundwater have been contaminated by leaking radioactive waste generated in the United States during the Cold War. A cleanup technology is being developed based on the extremely radiation resistant bacterium Deinococcus radiodurans that is being engineered to express bioremediating functions. Research aimed at developing D. radiodurans for organic toxin degradation in highly radioactive waste sites containing radionuclides, heavy metals, and toxic organic compounds was started by this group.Work funded by the existing grant has already contributed to eleven papers on the fundamental biology of D. radiodurans and its design for bioremediation of highly radioactive waste environments

  10. A Decade of Biochemical and Structural Studies of the DNA Repair Machinery of Deinococcus radiodurans: Major Findings, Functional and Mechanistic Insight and Challenges

    Directory of Open Access Journals (Sweden)

    Joanna Timmins

    2016-01-01

    Full Text Available The Deinococcus radiodurans bacterium is extremely resistant to ionising radiation and desiccation and can withstand a 200-fold higher radiation dose than most other bacteria with no loss of viability. The mechanisms behind this extreme resistance are not fully understood, but it is clear that several factors contribute to this phenotype. Efficient scavenging of reactive oxygen species and repair of damaged DNA are two of these. In this review, we summarise the results from a decade of structural and functional studies of the DNA repair machinery of Deinococcus radiodurans and discuss how these studies have contributed to an improved understanding of the molecular mechanisms underlying DNA repair and to the outstanding resistance of Deinococcus radiodurans to DNA damaging agents.

  11. A Decade of Biochemical and Structural Studies of the DNA Repair Machinery of Deinococcus radiodurans: Major Findings, Functional and Mechanistic Insight and Challenges.

    Science.gov (United States)

    Timmins, Joanna; Moe, Elin

    2016-01-01

    The Deinococcus radiodurans bacterium is extremely resistant to ionising radiation and desiccation and can withstand a 200-fold higher radiation dose than most other bacteria with no loss of viability. The mechanisms behind this extreme resistance are not fully understood, but it is clear that several factors contribute to this phenotype. Efficient scavenging of reactive oxygen species and repair of damaged DNA are two of these. In this review, we summarise the results from a decade of structural and functional studies of the DNA repair machinery of Deinococcus radiodurans and discuss how these studies have contributed to an improved understanding of the molecular mechanisms underlying DNA repair and to the outstanding resistance of Deinococcus radiodurans to DNA damaging agents.

  12. Expression of Deinococcus geothermalis trehalose synthase gene ...

    African Journals Online (AJOL)

    A novel trehalose synthase gene from Deinococcus geothermalis (DSMZ 11300) containing 1692 bp reading-frame encoding 564 amino acids was amplified using polymerase chain reaction (PCR). The gene was ligated into pET30Ek/LIC vector and expressed after isopropyl β-D-thiogalactopyranoside induction in ...

  13. The Western Sahara conflict I

    African Journals Online (AJOL)

    Politica; Analyst. Munich. The history of the Western Sahara has seen many developments familiar to Africa: • the drawing of artificial boundaries in foreign European capitals at the tum of the century,. • clandestine agreements between colonial and regional powers without proper consultation with the territory's population,.

  14. Identification of the methyltransferase targeting C2499 in Deinococcus radiodurans 23S ribosomal RNA

    DEFF Research Database (Denmark)

    Nielsen, Julie Mundus; Flyvbjerg, Karen Freund; Kirpekar, Finn

    2016-01-01

    The bacterium Deinococcus radiodurans-like all other organisms-introduces nucleotide modifications into its ribosomal RNA. We have previously found that the bacterium contains a Carbon-5 methylation on cytidine 2499 of its 23S ribosomal RNA, which is so far the only modified version of cytidine...... and in vivo. We also inactivated the DR_0049 gene in D. radiodurans through insertion of a chloramphenicol resistance cassette. This resulted in complete absence of the cytidine 2499 methylation, which all together demonstrates that DR_0049 encodes the methyltransferase producing m(5)C2499 in D. radiodurans...... 23S rRNA. Growth experiments disclosed that inactivation of DR_0049 is associated with a severe growth defect, but available ribosome structures show that cytidine 2499 is positioned very similar in D. radiodurans harbouring the modification and E. coli without the modification. Hence...

  15. High-coverage proteomics reveals methionine auxotrophy in Deinococcus radiodurans.

    Science.gov (United States)

    Zhou, Yanxia; Shen, Pan; Lan, Qiuyan; Deng, Chen; Zhang, Yao; Li, Yanchang; Wei, Wei; Wang, Yihao; Su, Na; He, Fuchu; Xie, Qiong; Lyu, Zhitang; Yang, Dong; Xu, Ping

    2017-07-01

    Deinococcus radiodurans is a robust bacterium best known for its capacity to resist to radiation. In this study, the SDS-PAGE coupled with high-precision LC-MS/MS was used to study the D. radiodurans proteome. A total of 1951 proteins were identified which covers 63.18% protein-coding genes. Comparison of the identified proteins to the key enzymes in amino acid biosyntheses from KEGG database showed the methionine biosynthesis module is incomplete while other amino acid biosynthesis modules are complete, which indicated methionine auxotrophy in D. radiodurans. The subsequent amino acid-auxotrophic screening has verified methionine instead of other amino acids is essential for the growth of D. radiodurans. With molecular evolutionary genetic analysis, we found the divergence in methionine biosynthesis during the evolution of the common ancestor of bacteria. We also found D. radiodurans lost the power of synthesizing methionine because of the missing metA and metX in two types of methionine biosyntheses. For the first time, this study used high-coverage proteome analysis to identify D. radiodurans amino acid auxotrophy, which provides the important reference for the development of quantitative proteomics analysis using stable isotope labeling in metabolomics of D. radiodurans and in-depth analysis of the molecular mechanism of radiation resistance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Purification and Characterization of Recombinant Deinococcus radiodurans RNA Polymerase.

    Science.gov (United States)

    Esyunina, D M; Kulbachinskiy, A V

    2015-10-01

    The radioresistant bacterium Deinococcus radiodurans is one of the most interesting models for studies of cell stress resistance. Analysis of the mechanisms of gene expression in D. radiodurans revealed some specific features of the transcription apparatus that might play a role in cell resistance to DNA-damaging conditions. In particular, RNA polymerase from D. radiodurans forms unstable promoter complexes and during transcription elongation has a much higher rate of RNA cleavage than RNA polymerase from Escherichia coli. Analysis of the structure and functions of D. radiodurans RNA polymerase is complicated due to the absence of convenient genetic systems for making mutations in the RNA polymerase genes and difficulties with enzyme purification. In this work, we developed a system for expression of D. radiodurans RNA polymerase in E. coli cells. We obtained an expression vector encoding all core RNA polymerase subunits and defined optimal conditions for the expression and purification of the RNA polymerase. It was found that D. radiodurans RNA polymerase has much higher rates of RNA cleavage than E. coli RNA polymerase under a wide range of conditions, including variations in the concentration of catalytic magnesium ions and pH values of the reaction buffer. The expression system can be used for further studies of the RNA cleavage reaction and the mechanisms of transcription regulation in D. radiodurans, including analysis of mutant RNA polymerase variants.

  17. High cell density production of Deinococcus radiodurans under optimized conditions.

    Science.gov (United States)

    He, Yi

    2009-04-01

    Deinococcus radiodurans is a bacterium being investigated for mechanisms of extreme radiation resistance and for bioremediation of environmental radioactive waste sites. In both fundamental and applied research settings, methods for large-scale production of D. radiodurans are needed. In this study, a systematic investigation was carried out to optimize D. radiodurans production at the 20-L fermentor scale. In defined medium, the phosphate buffer typically used was found to be inhibitory to D. radiodurans growth, and caused cell aggregation. Substitution of HEPES and MOPS buffers for phosphate buffer improved D. radiodurans growth characteristics. Several antifoaming agents were investigated to support large-scale production with submerged aeration, and the defoamer KFO 673 was chosen based on its ability to prevent foaming without affecting D. radiodurans growth. The conventional undefined rich medium tryptone/glucose/yeast extract (TGY) maximally supported D. radiodurans growth to an OD(600) of 10. Using a 'design of experiments' approach, we found glucose, Mg and Mn to be critical in supporting high-density growth of D. radiodurans. The optimal pH and temperature for D. radiodurans growth in large-scale preparations were 7.0 and 37 degrees C, respectively. Growth was carried out in a 20-L fermentor using the newly developed media under the optimal conditions. With addition of 10 g/L glucose, 0.5 g/L MgSO(4) . 7H(2)O, 5 microM MnCl(2) into TGY media, an OD(600) of 40 was achieved.

  18. Extracellular proteolytic activity of Deinococcus geothermalis ...

    African Journals Online (AJOL)

    Production of extracellular protease by extremophilic bacteria Deinococcus geothermalis cultivated in liquid media containing 0.1% (w/v) of peptone K, 0.1% yeast extract and 0.2% marine salt reached a maximum in 14 h of the cell growth at 45°C and pH 8.0. The enzyme was purified by a two-step procedure using ...

  19. The S-layer Protein DR_2577 Binds Deinoxanthin and under Desiccation Conditions Protects against UV-Radiation in Deinococcus radiodurans

    OpenAIRE

    Domenica eFarci; Chavdar eSlavov; Enzo eTramontano; Dario ePiano

    2016-01-01

    Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer) built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in desiccated cells. Moreove...

  20. A Decade of Biochemical and Structural Studies of the DNA Repair Machinery of Deinococcus radiodurans: Major Findings, Functional and Mechanistic Insight and Challenges

    OpenAIRE

    Timmins, Joanna; Moe, Elin

    2016-01-01

    Published version. Source at http://dx.doi.org/10.1016/j.csbj.2016.04.001 The Deinococcus radiodurans bacterium is extremely resistant to ionising radiation and desiccation and can withstand a 200-fold higher radiation dose than most other bacteria with no loss of viability. The mechanisms behind this extreme resistance are not fully understood, but it is clear that several factors contribute to this phenotype. Efficient scavenging of reactive oxygen species and repair of damage...

  1. Going under the radar in Western Sahara

    OpenAIRE

    Wilson, Alice

    2016-01-01

    At the level of formal attempts at conflict resolution, the Western Sahara conflict has been locked in a political stalemate for years. One consequence is that the people of Western Sahara are often overlooked in their own conflict – despite the fact that the very case for decolonization in Western Sahara hinges upon the right of the people of the territory to self-determination. This essay examines how, despite the ongoing formal stalemate, under the radar of formal politics in recent years ...

  2. CYP287A1 is a carotenoid 2-β-hydroxylase required for deinoxanthin biosynthesis in Deinococcus radiodurans R1.

    Science.gov (United States)

    Zhou, Zhengfu; Zhang, Wei; Su, Shiyou; Chen, Ming; Lu, Wei; Lin, Min; Molnár, István; Xu, Yuquan

    2015-12-01

    The carotenoid deinoxanthin is a crucial resistance factor against various stresses in the radiation-resistant bacterium Deinococcus radiodurans. Disruption of the gene dr2473 encoding the cytochrome P450 CYP287A1 led to the accumulation of 2-deoxydeinoxanthin in D. radiodurans, demonstrating that CYP287A1 is a novel β-carotene 2-hydroxylase. The dr2473 knockout mutant was shown to be more sensitive to UV radiation and oxidative stress than the wild-type strain D. radiodurans R1, indicating that the C2 alcohol of deinoxanthin is important for antioxidant activity.

  3. Purification and characterization of DR_2577 (SlpA a major S-layer protein from Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Domenica eFarci

    2015-06-01

    Full Text Available The protein DR_2577 is a major Surface layer component of the radio-resistant bacterium Deinococcus radiodurans. In the present study DR_2577 has been purified and its oligomeric profile characterized by means of size exclusion chromatography and gel electrophoresis. DR_2577 was found to be organized into three hierarchical orders characterized by monomers, stable dimers formed by the occurrence of disulphide bonds, and hexamers resulting from a combination of dimers. The structural implications of these findings are discussed providing new elements for a more integrated model of this S-layer.

  4. Nutrition induced pleomorphism and budding mode of reproduction in Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Toleti Rao S

    2009-07-01

    Full Text Available Abstract Background Morphological adaptation is an important biological function of a microorganism to cope with its environment. Pleomorphism (to exist in a number of morphological forms took centre stage in many discussions wherein a bacterium exhibits morphological transition and altered mode of reproduction in response to an environmental condition. Findings To strengthen the concept on pleomorphism in bacteria, we report here different cell morphologies of Deinococcus radiodurans in response to variation in nutrient concentration. From our studies we attempt primary evidence towards the presence of significant population of monomer cells of D. radiodurans in specific culture condition. In this report we also illustrate with scanning electron micrographs an unusual budding mode of reproduction in D. radiodurans which was not reported till date for this group of bacteria. Conclusion In a holistic view the study reflects on bacterial shape (morphotypes and the physiological adaptation to a particular nutrient environment. The discovery of budding mode of reproduction in Deinococcus will be of interest to microbiologists. It can serve as a model system to understand the mechanism of budding process at molecular level.

  5. Purification, crystallization and preliminary crystallographic investigation of FrnE, a disulfide oxidoreductase from Deinococcus radiodurans.

    Science.gov (United States)

    Panicker, Lata; Misra, Hari Sharan; Bihani, Subhash Chandra

    2014-11-01

    In prokaryotes, Dsb proteins catalyze the formation of native disulfide bonds through an oxidative folding pathway and are part of the cell machinery that protects proteins from oxidative stress. Deinococcus radiodurans is an extremophile which shows unparalleled resistance to ionizing radiation and oxidative stress. It has a strong mechanism to protect its proteome from oxidative damage. The genome of Deinococcus shows the presence of FrnE, a Dsb protein homologue that potentially provides the bacterium with oxidative stress tolerance. Here, crystallization and preliminary X-ray crystallographic analysis of FrnE from D. radiodurans are reported. Diffraction-quality single crystals were obtained using the hanging-drop vapour-diffusion method with reservoir solution consisting of 100 mM sodium acetate pH 5.0, 10% PEG 8000, 15-20% glycerol. Diffraction data were collected on an Agilent SuperNova system using a microfocus sealed-tube X-ray source. The crystal diffracted to 1.8 Å resolution at 100 K. The space group of the crystal was found to be P2₁22₁, with unit-cell parameters a=47.91, b=62.94, c=86.75 Å, α=β=γ=90°. Based on Matthews coefficient analysis, one monomer per asymmetric unit is present in the crystal, with a solvent content of approximately 45%.

  6. Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

    Energy Technology Data Exchange (ETDEWEB)

    Makarova, Kira S. [National Center for Biotechnology Information; Omelchenko, Marina [National Center for Biotechnology Information; Gaidamakova, Elena [Uniformed Services University of the Health Sciences (USUHS); Matrosova, Vera [Uniformed Services University of the Health Sciences (USUHS); Vasilenko, Alexander [Uniformed Services University of the Health Sciences (USUHS); Zhai, Min [Uniformed Services University of the Health Sciences (USUHS); Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Kim, Edwin [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Pitluck, Samual [U.S. Department of Energy, Joint Genome Institute; Richardson, P M [U.S. Department of Energy, Joint Genome Institute; Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Brettin, Tom [Los Alamos National Laboratory (LANL); Saunders, Elizabeth H [Los Alamos National Laboratory (LANL); Lai, Barry [Argonne National Laboratory (ANL); Ravel, Bruce [Argonne National Laboratory (ANL); Kemner, Kenneth M [Argonne National Laboratory (ANL); Wolf, Yuri [National Center for Biotechnology Information; Sorokin, Alexei [Genetique Microbienne; Gerasimova, Anna [Research Institute of Genetics and Selection of Industrial Microorganisms, Mosco; Gelfand, Mikhail [Moscow State University; Fredrickson, James K [Pacific Northwest National Laboratory (PNNL); Koonin, Eugene [National Center for Biotechnology Information; Daly, Michael [Uniformed Services University of the Health Sciences (USUHS)

    2007-01-01

    Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to

  7. Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

    Energy Technology Data Exchange (ETDEWEB)

    Makarova, Kira S.; Omelchenko, Marina V.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Vasilenko, Alexander; Zhai, Min; Lapidus, Alla; Copeland, Alex; Kim, Edwin; Land, Miriam; Mavrommatis, Konstantinos; Pitluck, Samuel; Richardson, Paul M.; Detter, Chris; Brettin, Thomas; Saunders, Elizabeth; Lai, Barry; Ravel, Bruce; Kemner, Kenneth M.; Wolf, Yuri I.; Sorokin, Alexander; Gerasimova, Anna V.; Gelfand, Mikhail S.; Fredrickson, James K.; Koonin, Eugene V.; Daly, Michael J.

    2007-07-24

    Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at itsoptimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to

  8. Deinococcus geothermalis: the pool of extreme radiation resistance genes shrinks.

    Directory of Open Access Journals (Sweden)

    Kira S Makarova

    2007-09-01

    Full Text Available Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR, ultraviolet light (UV and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and

  9. [Biosorption of Radionuclide Uranium by Deinococcus radiodurans].

    Science.gov (United States)

    Yang, Jie; Dong, Fa-qin; Dai, Qun-wei; Liu, Ming-xue; Nie, Xiao-qin; Zhang, Dong; Ma, Jia-lin; Zhou, Xian

    2015-04-01

    As a biological adsorbent, Living Deinococcus radiodurans was used for removing radionuclide uranium in the aqueous solution. The effect factors on biosorption of radionuclide uranium were researched in the present paper, including solution pH values and initial uranium concentration. Meanwhile, the biosorption mechanism was researched by the method of FTIR and SEM/EDS. The results show that the optimum conditions for biosorption are as follows: pH = 5, co = 100 mg · L(-1) and the maximum biosorption capacity is up to 240 mgU · g(-1). According to the SEM results and EDXS analysis, it is indicated that the cell surface is attached by lots of sheet uranium crystals, and the main biosorpiton way of uranium is the ion exchange or surface complexation. Comparing FTIR spectra and FTIR fitting spectra before and after biosorption, we can find that the whole spectra has a certain change, particularly active groups (such as amide groups of the protein, hydroxy, carboxyl and phosphate group) are involved in the biosorption process. Then, there is a new peak at 906 cm(-1) and it is a stretching vibration peak of UO2(2+). Obviously, it is possible that as an anti radiation microorganism, Deinococcus radiodurans could be used for removing radionuclide uranium in radiation environment.

  10. Manganese binding to antioxidant peptides involved in extreme radiation resistance in Deinococcus radiodurans.

    Science.gov (United States)

    Peana, Massimiliano; Medici, Serenella; Pangburn, Heather A; Lamkin, Thomas J; Ostrowska, Malgorzata; Gumienna-Kontecka, Elzbieta; Zoroddu, Maria Antonietta

    2016-11-01

    A decapeptide, DEHGTAVMLK (DP1), and its random scrambled version, THMVLAKGED (DP2), have been studied for their interactions with manganese. The amino acid composition of the peptides was selected to include the majority of the most prevalent amino acids present in a Deinococcus radiodurans bacterium cell-free extract that contains components capable of conferring extreme resistance to ionizing radiation. The extract appears to be rich in Mn(II) complexes which seem to be responsible for protecting proteins from Reactive Oxygen Species damage. We focused our attention on the interaction of the decapeptides with Mn(II) ion with the aim of obtaining information on the possible complexes formed, by using NMR, EPR, and ESI-MS techniques. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Differential radio-tolerance of nutrition-induced morphotypes of Deinococcus radiodurans R1.

    Science.gov (United States)

    Shukla, Sudhir K; Sankar, G Gomathi; Paraneeiswaran, A; Rao, T Subba

    2014-02-01

    Deinococcus radiodurans R1 is a highly radio-tolerant bacterium. Depending on the nutrient availability D. radiodurans R1 exists in three morphologies viz. monococcal, diplococcal and tetracoccal. In this study, we examined whether nutrition-induced morphotypes of D. radiodurans showed similar DNA damage upon gamma radiation exposure. Total DNA damage after radiation exposure was estimated by comparing percent double-strand breaks (DSBs) in genomic DNA. It was found that all three morphotypes exhibited different radiation tolerances which were also dependent on the radiation dose given. Monococcal forms were found to be most radio-tolerant at most of the tested radiation doses. Results showed that these nutrient-starved-condition induced morphotypes show lesser DNA DSBs upon irradiation, hence show higher radio-tolerance.

  12. Laboratory simulation of interplanetary ultraviolet radiation (broad spectrum) and its effects on Deinococcus radiodurans

    Science.gov (United States)

    Paulino-Lima, Ivan Gláucio; Pilling, Sérgio; Janot-Pacheco, Eduardo; de Brito, Arnaldo Naves; Barbosa, João Alexandre Ribeiro Gonçalves; Leitão, Alvaro Costa; Lage, Claudia de Alencar Santos

    2010-08-01

    The radiation-resistant bacterium Deinococcus radiodurans was exposed to a simulated interplanetary UV radiation at the Brazilian Synchrotron Light Laboratory (LNLS). Bacterial samples were irradiated on different substrates to investigate the influence of surface relief on cell survival. The effects of cell multi-layers were also investigated. The ratio of viable microorganisms remained virtually the same (average 2%) for integrated doses from 1.2 to 12 kJ m -2, corresponding to 16 h of irradiation at most. The asymptotic profiles of the curves, clearly connected to a shielding effect provided by multi-layering cells on a cavitary substrate (carbon tape), means that the inactivation rate may not change significantly along extended periods of exposure to radiation. Such high survival rates reinforce the possibility of an interplanetary transfer of viable microbes.

  13. Cretaceous Crocodyliforms from the Sahara

    Directory of Open Access Journals (Sweden)

    Paul Sereno

    2009-11-01

    Full Text Available Diverse crocodyliforms have been discovered in recent years in Cretaceous rocks on southern landmasses formerly composing Gondwana.  We report here on six species from the Sahara with an array of trophic adaptations that significantly deepen our current understanding of African crocodyliform diversity during the Cretaceous period.  We describe two of these species (Anatosuchus minor, Araripesuchus wegeneri from nearly complete skulls and partial articulated skeletons from the Lower Cretaceous Elrhaz Formation (Aptian-Albian of Niger. The remaining four species (Araripesuchus rattoides sp. n., Kaprosuchus saharicus gen. n. sp. n., Laganosuchus thaumastos gen. n. sp. n., Laganosuchus maghrebensis gen. n. sp. n. come from contemporaneous Upper Cretaceous formations (Cenomanian in Niger and Morocco.

  14. Complete genome sequence of Deinococcus maricopensis type strain (LB-34).

    Science.gov (United States)

    Pukall, Rüdiger; Zeytun, Ahmet; Lucas, Susan; Lapidus, Alla; Hammon, Nancy; Deshpande, Shweta; Nolan, Matt; Cheng, Jan-Fang; Pitluck, Sam; Liolios, Konstantinos; Pagani, Ioanna; Mikhailova, Natalia; Ivanova, Natalia; Mavromatis, Konstantinos; Pati, Amrita; Tapia, Roxane; Han, Cliff; Goodwin, Lynne; Chen, Amy; Palaniappan, Krishna; Land, Miriam; Hauser, Loren; Chang, Yun-Juan; Jeffries, Cynthia D; Brambilla, Evelyne-Marie; Rohde, Manfred; Göker, Markus; Detter, J Chris; Woyke, Tanja; Bristow, James; Eisen, Jonathan A; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter

    2011-04-29

    Deinococcus maricopensis (Rainey and da Costa 2005) is a member of the genus Deinococcus, which is comprised of 44 validly named species and is located within the deeply branching bacterial phylum Deinococcus-Thermus. Strain LB-34(T) was isolated from a soil sample from the Sonoran Desert in Arizona. Various species of the genus Deinococcus are characterized by extreme radiation resistance, with D. maricopensis being resistant in excess of 10 kGy. Even though the genomes of three Deinococcus species, D. radiodurans, D. geothermalis and D. deserti, have already been published, no special physiological characteristic is currently known that is unique to this group. It is therefore of special interest to analyze the genomes of additional species of the genus Deinococcus to better understand how these species adapted to gamma- or UV ionizing-radiation. The 3,498,530 bp long genome of D. maricopensis with its 3,301 protein-coding and 66 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  15. The Deinococcus radiodurans DR1245 Protein, a DdrB Partner Homologous to YbjN Proteins and Reminiscent of Type III Secretion System Chaperones

    Science.gov (United States)

    Bouthier-de-la-Tour, Claire; Coureux, Pierre-Damien; Ithurbide, Solenne; Vannier, Françoise; Guerin, Philippe P.; Dulberger, Charles L.; Satyshur, Kenneth A.; Keck, James L.; Armengaud, Jean; Cox, Michael M.; Sommer, Suzanne

    2013-01-01

    The bacterium Deinococcus radiodurans exhibits an extreme resistance to ionizing radiation. A small subset of Deinococcus genus-specific genes were shown to be up-regulated upon exposure to ionizing radiation and to play a role in genome reconstitution. These genes include an SSB-like protein called DdrB. Here, we identified a novel protein encoded by the dr1245 gene as an interacting partner of DdrB. A strain devoid of the DR1245 protein is impaired in growth, exhibiting a generation time approximately threefold that of the wild type strain while radioresistance is not affected. We determined the three-dimensional structure of DR1245, revealing a relationship with type III secretion system chaperones and YbjN family proteins. Thus, DR1245 may display some chaperone activity towards DdrB and possibly other substrates. PMID:23441204

  16. The Deinococcus radiodurans DR1245 Protein, a DdrB Partner Homologous to YbjN Proteins and Reminiscent of Type III Secretion System Chaperones

    Energy Technology Data Exchange (ETDEWEB)

    Norais, Cédric [Univ. of Wisconsin, Madison, WI (United States); Ecole Polytechnic, Paaiseau (France); Servant, Pascale [Univ. of Paris-Sud, Orsay (France); National Center of Scientific Research, Orsay (France); Bouthier-de-la-Tour, Claire [Univ. of Paris-Sud, Orsay (France); National Center of Scientific Research, Orsay (France); Coureux, Pierre-Damien [Ecole Polytechnic, Paaiseau (France); Ithurbide, Solenne [Univ. of Paris-Sud, Orsay (France); National Center of Scientific Research, Orsay (France); Vannier, Françoise [Univ. of Paris-Sud, Orsay (France); National Center of Scientific Research, Orsay (France); Guerin, Philippe P. [French Alternatives Energy Commission (France); Dulberger, Charles L. [Univ. of Wisconsin, Madison, WI (United States); Satyshur, Kenneth A. [Univ. of Wisconsin, Madison, WI (United States); Keck, James L. [Univ. of Wisconsin, Madison, WI (United States); Armengaud, Jean [French Alternatives Energy Commission (France); Cox, Michael M. [Univ. of Wisconsin, Madison, WI (United States); Sommer, Suzanne [Univ. of Paris-Sud, Orsay (France); National Center of Scientific Research, Orsay (France)

    2013-02-18

    The bacterium Deinococcus radiodurans exhibits an extreme resistance to ionizing radiation. A small subset of Deinococcus genus-specific genes were shown to be up-regulated upon exposure to ionizing radiation and to play a role in genome reconstitution. These genes include an SSB-like protein called DdrB. Here, we identified a novel protein encoded by the dr1245gene as an interacting partner of DdrB. A strain devoid of the DR1245 protein is impaired in growth, exhibiting a generation time approximately threefold that of the wild type strain while radioresistance is not affected. We determined the three-dimensional structure of DR1245, revealing a relationship with type III secretion system chaperones and YbjN family proteins. Thus, DR1245 may display some chaperone activity towards DdrB and possibly other substrates.

  17. The Deinococcus radiodurans DR1245 protein, a DdrB partner homologous to YbjN proteins and reminiscent of type III secretion system chaperones.

    Directory of Open Access Journals (Sweden)

    Cédric Norais

    Full Text Available The bacterium Deinococcus radiodurans exhibits an extreme resistance to ionizing radiation. A small subset of Deinococcus genus-specific genes were shown to be up-regulated upon exposure to ionizing radiation and to play a role in genome reconstitution. These genes include an SSB-like protein called DdrB. Here, we identified a novel protein encoded by the dr1245 gene as an interacting partner of DdrB. A strain devoid of the DR1245 protein is impaired in growth, exhibiting a generation time approximately threefold that of the wild type strain while radioresistance is not affected. We determined the three-dimensional structure of DR1245, revealing a relationship with type III secretion system chaperones and YbjN family proteins. Thus, DR1245 may display some chaperone activity towards DdrB and possibly other substrates.

  18. Extreme Ionizing-Radiation-Resistant Bacterium

    Science.gov (United States)

    Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

    2013-01-01

    potential for transfer, and subsequent proliferation, on another solar body such as Mars and Europa. These organisms are more likely to escape planetary protection assays, which only take into account presence of spores. Hence, presences of extreme radiation-resistant Deinococcus in the cleanroom facility where spacecraft are assembled pose a serious risk for integrity of life-detection missions. The microorganism described herein was isolated from the surfaces of the cleanroom facility in which the Phoenix Lander was assembled. The isolated bacterial strain was subjected to a comprehensive polyphasic analysis to characterize its taxonomic position. This bacterium exhibits very low 16SrRNA similarity with any other environmental isolate reported to date. Both phenotypic and phylogenetic analyses clearly indicate that this isolate belongs to the genus Deinococcus and represents a novel species. The name Deinococcus phoenicis was proposed after the Phoenix spacecraft, which was undergoing assembly, testing, and launch operations in the spacecraft assembly facility at the time of isolation. D. phoenicis cells exhibited higher resistance to ionizing radiation (cobalt-60; 14 kGy) than the cells of the D. radiodurans (5 kGy). Thus, it is in the best interest of NASA to thoroughly characterize this organism, which will further assess in determining the potential for forward contamination. Upon the completion of genetic and physiological characteristics of D. phoenicis, it will be added to a planetary protection database to be able to further model and predict the probability of forward contamination.

  19. The S-layer Protein DR_2577 Binds Deinoxanthin and under Desiccation Conditions Protects against UV-Radiation in Deinococcus radiodurans.

    Science.gov (United States)

    Farci, Domenica; Slavov, Chavdar; Tramontano, Enzo; Piano, Dario

    2016-01-01

    Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer) built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in desiccated cells. Moreover, we show that the DR_2577 protein binds the carotenoid deinoxanthin, a strong protective antioxidant specific of this bacterium. A further spectroscopical characterization of the deinoxanthin-DR_2577 complex revealed features which could suggest a protective role of DR_2577. We propose that, especially under desiccation, the S-layer shields the bacterium from incident ultraviolet light and could behave as a first lane of defense against UV radiation.

  20. The S-layer protein DR_2577 binds deinoxanthin and under desiccation conditions protect against UV-radiation in Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Domenica eFarci

    2016-02-01

    Full Text Available Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in dessicated cells. Moreover, we show that the DR_2577 protein binds the carotenoid deinoxanthin, a strong protective antioxidant specific of this bacterium. A further spectroscopical characterization of the deinoxanthin-DR_2577 complex revealed features which could suggest a protective role of DR_2577. We propose that, especially under dessication, the S-layer shields the bacterium from incident ultraviolet light and could behave as a first lane of defence against UV radiation.

  1. RecA Proteins from Deinococcus geothermalis and Deinococcus murrayi - Cloning, Purification and Biochemical Characterisation

    Directory of Open Access Journals (Sweden)

    Kur Józef

    2011-04-01

    Full Text Available Abstract Background Escherichia coli RecA plays a crucial role in recombinational processes, the induction of SOS responses and mutagenic lesion bypasses. It has also been demonstrated that RecA protein is indispensable when it comes to the reassembly of shattered chromosomes in γ-irradiated Deinococcus radiodurans, one of the most radiation-resistant organisms known. Moreover, some functional differences between E. coli and D. radiodurans RecA proteins have also been shown. Results In this study, recA genes from Deinococcus geothermalis and Deinococcus murrayi, bacteria that are slightly thermophilic and extremely γ-radiation resistant, were isolated, cloned and expressed in E. coli. After production and purification, the biochemical properties of DgeRecA and DmuRecA proteins were determined. Both proteins continued to exist in the solutions as heterogenous populations of oligomeric forms. The DNA binding by DgeRecA and DmuRecA proteins is stimulated by Mg2+ ions. Furthermore, both proteins bind more readily to ssDNA when ssDNA and dsDNA are in the same reaction mixture. Both proteins are slightly thermostable and were completely inactivated in 10 s at 80°C. Both proteins hydrolyze ATP and dATP in the presence of ssDNA or complementary ssDNA and dsDNA, but not in the absence of DNA or in the presence of dsDNA only, and dATP was hydrolyzed more rapidly than ATP. They were also able to promote DNA strand exchange reactions by a pathway common for other RecA proteins. However, we did not obtain DNA strand exchange products when reactions were performed on an inverse pathway, characteristic for RecA of D. radiodurans. Conclusions The characterization of DgeRecA and DmuRecA proteins made in this study indicates that the unique properties of D. radiodurans RecA are probably not common among RecA proteins from Deinococcus sp.

  2. Identification and Functional Analysis of RelA/SpoT Homolog (RSH) Genes in Deinococcus radiodurans.

    Science.gov (United States)

    Wang, Jinhui; Tian, Ye; Zhou, Zhengfu; Zhang, Liwen; Zhang, Wei; Lin, Min; Chen, Ming

    2016-12-28

    To identify the global effects of (p)ppGpp in the gram-positive bacterium Deinococcus radiodurans, which exhibits remarkable resistance to radiation and other stresses, RelA/SpoT homolog (RSHs) mutants were constructed by direct deletion mutagenesis. The results showed that RelA has both synthesis and hydrolysis domains of (p)ppGpp, whereas RelQ only synthesizes (p)ppGpp in D. radiodurans. The growth assay for mutants and complementation analysis revealed that deletion of relA and relQ sensitized the cells to H₂O₂, heat shock, and amino acid limitation. Comparative proteomic analysis revealed that the bifunctional RelA is involved in DNA repair, molecular chaperone functions, transcription, the tricarboxylic acid cycle, and metabolism, suggesting that relA maintains the cellular (p)ppGpp levels and plays a crucial role in oxidative resistance in D. radiodurans. The D. radiodurans relA and relQ genes are responsible for (p)ppGpp synthesis/hydrolysis and (p)ppGpp hydrolysis, respectively. (p)ppGpp integrates a general stress response with a targeted re-programming of gene regulation to allow bacteria to respond appropriately towards heat shock, oxidative stress, and starvation. This is the first identification of RelA and RelQ involvement in response to oxidative, heat shock, and starvation stresses in D. radiodurans, which further elucidates the remarkable resistance of this bacterium to stresses.

  3. Identification of the methyltransferase targeting C2499 in Deinococcus radiodurans 23S ribosomal RNA.

    Science.gov (United States)

    Mundus, Julie; Flyvbjerg, Karen Freund; Kirpekar, Finn

    2016-01-01

    The bacterium Deinococcus radiodurans-like all other organisms-introduces nucleotide modifications into its ribosomal RNA. We have previously found that the bacterium contains a Carbon-5 methylation on cytidine 2499 of its 23S ribosomal RNA, which is so far the only modified version of cytidine 2499 reported. Using homology search, we identified the open reading frame DR_0049 as the primary candidate gene for the methyltransferase that modifies cytidine 2499. Mass spectrometric analysis demonstrated that recombinantly expressed DR0049 protein methylates E. coli cytidine 2499 both in vitro and in vivo. We also inactivated the DR_0049 gene in D. radiodurans through insertion of a chloramphenicol resistance cassette. This resulted in complete absence of the cytidine 2499 methylation, which all together demonstrates that DR_0049 encodes the methyltransferase producing m(5)C2499 in D. radiodurans 23S rRNA. Growth experiments disclosed that inactivation of DR_0049 is associated with a severe growth defect, but available ribosome structures show that cytidine 2499 is positioned very similar in D. radiodurans harbouring the modification and E. coli without the modification. Hence there is no obvious structure-based explanation for the requirement for the C2499 posttranscriptional modification in D. radiodurans.

  4. Extremely high intracellular concentration of glucose-6-phosphate and NAD(H) in Deinococcus radiodurans.

    Science.gov (United States)

    Yamashiro, Takumi; Murata, Kousaku; Kawai, Shigeyuki

    2017-03-01

    Deinococcus radiodurans is highly resistant to ionizing radiation and UV radiation, and oxidative stress caused by such radiations. NADP(H) seems to be important for this resistance (Slade and Radman, Microbiol Mol Biol Rev 75:133-191; Slade, Radman, Microbiol Mol Biol Rev 75:133-191, 2011), but the mechanism underlying the generation of NADP(H) or NAD(H) in D. radiodurans has not fully been addressed. Intracellular concentrations of NAD(+), NADH, NADP(+), and NADPH in D. radiodurans are also not determined yet. We found that cell extracts of D. radiodurans catalyzed reduction of NAD(P)(+) in vitro, indicating that D. radiodurans cells contain both enzymes and a high concentration of substrates for this activity. The enzyme and the substrate were attributed to glucose-6-phosphate dehydrogenase and glucose-6-phosphate of which intracellular concentration was extremely high. Unexpectedly, the intracellular concentration of NAD(H) was also much greater than that of NADP(H), suggesting some significant roles of NADH. These unusual features of this bacterium would shed light on a new aspect of physiology of this bacterium.

  5. Influence of LET on repair of DNA damages in Deinococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Y.; Tanaka, A.; Kikuchi, M.; Shimizu, T.; Watanabe, H. [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Cao, J.P.; Taucher-Scholz, G.

    1997-03-01

    Inactivation caused by heavy ions was studied in dry cells of radioresistant bacterium Deinococcus radiodurans. All survival curves were characterized by a large shoulder of the curves. No final slopes of the exponential part of survival curves for heavy ion irradiation were steeper than that for 2.0 MeV electron irradiation. The plots of RBE versus LET showed no obvious peaks, suggesting that this bacterium can repair not only DNA double strand breaks (DSBs) but also clustered damage in DNA which may be induced by heavy ions. The genomic DNA of D. radiodurans was cleaved into large fragments with restriction enzyme Not I after post-irradiation incubation and the fragments were separated using pulsed-field gel electrophoresis (PFGE). DSBs induction and rejoining process were analyzed by detection of the reappearance of ladder pattern of DNA fragments. The required repair time after heavy ions irradiation was longer than the repair time for electrons at the same dose of irradiation, however, the rate of repair enzyme induction was almost similar to each other between electrons and heavy ions, suggesting that the same repair system is likely to be used after both low and high LET irradiations. (author)

  6. Genome Signature Difference between Deinococcus radiodurans and Thermus thermophilus

    Directory of Open Access Journals (Sweden)

    Hiromi Nishida

    2012-01-01

    Full Text Available The extremely radioresistant bacteria of the genus Deinococcus and the extremely thermophilic bacteria of the genus Thermus belong to a common taxonomic group. Considering the distinct living environments of Deinococcus and Thermus, different genes would have been acquired through horizontal gene transfer after their divergence from a common ancestor. Their guanine-cytosine (GC contents are similar; however, we hypothesized that their genomic signatures would be different. Our findings indicated that the genomes of Deinococcus radiodurans and Thermus thermophilus have different tetranucleotide frequencies. This analysis showed that the genome signature of D. radiodurans is most similar to that of Pseudomonas aeruginosa, whereas the genome signature of T. thermophilus is most similar to that of Thermanaerovibrio acidaminovorans. This difference in genome signatures may be related to the different evolutionary backgrounds of the 2 genera after their divergence from a common ancestor.

  7. Bioprecipitation of uranium from alkaline waste solutions using recombinant Deinococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, Sayali; Ballal, Anand; Apte, Shree Kumar, E-mail: aptesk@barc.gov.in

    2013-11-15

    Highlights: • Deinococcus radiodurans was genetically engineered to overexpress alkaline phosphatase (PhoK). • Deino-PhoK bioprecipitated U efficiently over a wide range of input U concentration. • A maximal loading of 10.7 g U/g of biomass at 10 mM input U was observed. • Radioresistance and U precipitation by Deino-PhoK remained unaffected by γ radiation. • Immobilization of Deino-PhoK facilitated easy separation of precipitated U. -- Abstract: Bioremediation of uranium (U) from alkaline waste solutions remains inadequately explored. We engineered the phoK gene (encoding a novel alkaline phosphatase, PhoK) from Sphingomonas sp. for overexpression in the radioresistant bacterium Deinococcus radiodurans. The recombinant strain thus obtained (Deino-PhoK) exhibited remarkably high alkaline phosphatase activity as evidenced by zymographic and enzyme activity assays. Deino-PhoK cells could efficiently precipitate uranium over a wide range of input U concentrations. At low uranyl concentrations (1 mM), the strain precipitated >90% of uranium within 2 h while a high loading capacity of around 10.7 g U/g of dry weight of cells was achieved at 10 mM U concentration. Uranium bioprecipitation by Deino-PhoK cells was not affected in the presence of Cs and Sr, commonly present in intermediate and low level liquid radioactive waste, or after exposure to very high doses of ionizing radiation. Transmission electron micrographs revealed the extracellular nature of bioprecipitated U, while X-ray diffraction and fluorescence analysis identified the precipitated uranyl phosphate species as chernikovite. When immobilized into calcium alginate beads, Deino-PhoK cells efficiently removed uranium, which remained trapped in beads, thus accomplishing physical separation of precipitated uranyl phosphate from solutions. The data demonstrate superior ability of Deino-PhoK, over earlier reported strains, in removal of uranium from alkaline solutions and its potential use in

  8. Murzuk Sand Sea, Sahara Desert, Libya, Africa

    Science.gov (United States)

    1993-01-01

    This near vertical view of the Murzuk Sand Sea, Sahara Desert, Libya (22.5N, 13.0E) shows the very diverse landscape that is part of the great Sahara Desert of North Africa. The vast expanse of sand dunes known as the Murzuk sand Sea of Libya and the adjacent rock outcrops support little human habitation. In fact, the tiny village of Murzuk with its center pivot, swing arm irrigated agriculture complex is the only sign of life in the region.

  9. Cenozoic stratigraphy of the Sahara, Northern Africa

    Science.gov (United States)

    Swezey, Christopher S.

    2009-01-01

    This paper presents an overview of the Cenozoic stratigraphic record in the Sahara, and shows that the strata display some remarkably similar characteristics across much of the region. In fact, some lithologies of certain ages are exceptionally widespread and persistent, and many of the changes from one lithology to another appear to have been relatively synchronous across the Sahara. The general stratigraphic succession is that of a transition from early Cenozoic carbonate strata to late Cenozoic siliciclastic strata. This transition in lithology coincides with a long-term eustatic fall in sea level since the middle Cretaceous and with a global climate transition from a Late Cretaceous–Early Eocene “warm mode” to a Late Eocene–Quaternary “cool mode”. Much of the shorter-term stratigraphic variability in the Sahara (and even the regional unconformities) also can be correlated with specific changes in sea level, climate, and tectonic activity during the Cenozoic. Specifically, Paleocene and Eocene carbonate strata and phosphate are suggestive of a warm and humid climate, whereas latest Eocene evaporitic strata (and an end-Eocene regional unconformity) are correlated with a eustatic fall in sea level, the build-up of ice in Antarctica, and the appearance of relatively arid climates in the Sahara. The absence of Oligocene strata throughout much of the Sahara is attributed to the effects of generally low eustatic sea level during the Oligocene and tectonic uplift in certain areas during the Late Eocene and Oligocene. Miocene sandstone and conglomerate are attributed to the effects of continued tectonic uplift around the Sahara, generally low eustatic sea level, and enough rainfall to support the development of extensive fluvial systems. Middle–Upper Miocene carbonate strata accumulated in northern Libya in response to a eustatic rise in sea level, whereas Upper Miocene mudstone accumulated along the south side of the Atlas Mountains because uplift of the

  10. Final Report for Grant No. DE-FG02-98ER62583 ''Functional Analysis of the Genome Sequence of Deinococcus radiodurans''

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Daly, Ph.D.

    2003-10-15

    Extremophiles are nearly always defined with singular characteristics that allow existence within a singular extreme environment. The bacterium Deinococcus radiodurans qualifies as a polyextremeophile, showing remarkable resistance to a range of damage caused by ionizing radiation, dessication, ultraviolet radiation, oxidizing agents, and electrophilic mutagens. D. radiodurans is most famous for its extreme resistance to ionizing radiation; it not only can grow continuously in the presence of chronic radiation (6,000 rad per hour), but it can survive acute exposures to gamma radiation that exceed 1,500,000 rads without lethality or induced mutation. These characteristics were the impetus for sequencing its genome. We completed an extensive comparative sequence analysis of the Deinococcus radiodurans (strain R1) genome. Deinococcus is the first representative with a completely sequenced genome from a bacterial branch of extremophiles - the Thermus/Deinococcus group. Phylogenetic tree analysis, combined with the identification of several synapomorphies between Thermus and Deinococcus, support that it is a very ancient branch localized in the vicinity of the bacterial tree root. Distinctive features of the Deinoccoccus genome as well as features shared with other free-living bacteria were revealed by comparison of its proteome to a collection of Clusters of Orthologous Groups of proteins (COGs). Analysis of paralogs in Deinococcus has revealed some unique protein families. In addition, specific expansions of several protein families including phosphatases, proteases, acyl transferases and MutT pyrophosphohydrolases, were detected. Genes that potentially affect DNA repair and recombination were investigated in detail. Some proteins appear to have been horizontally transferred from eukaryotes, and are not present in other bacteria. For example, three proteins homologous to plant desiccation-resistance proteins were identified and these are particularly interesting

  11. Eghindi among Sahrawi refugees of Western Sahara

    NARCIS (Netherlands)

    Volpato, G.

    2014-01-01

    Eghindi is an illness built around a set of pathological states experienced by Sahrawi in the desert environment of Western Sahara. Its core symptoms are caused by osmotic imbalances related to salt consumption. In 1975, many Sahrawi were exiled into refugee camps, and they have since experienced

  12. ion transporter genes (DR1709 and DR2523) in Deinococcus ...

    African Journals Online (AJOL)

    Deinococcus radiodurans is best known for its extraordinary radiation resistance. Manganese(II) ions can protect proteins from being damaged by super radicals, which is supposed to be the main mechanism through which D. radiodurans has the strong radiation resistance. But the detailed molecular and physiological ...

  13. Bacterial composition and survival on Sahara dust particles transported to the European Alps

    Directory of Open Access Journals (Sweden)

    Marco eMeola

    2015-12-01

    Full Text Available Deposition of Sahara dust (SD particles is a frequent phenomenon in Europe, but little is known about the viability and composition of the bacterial community transported with SD. The goal of this study was to characterize SD-associated bacteria transported to the European Alps, deposited and entrapped in snow. During two distinct events in February and May 2014, SD particles were deposited and promptly covered by falling snow, thus preserving them in distinct ochre layers within the snowpack. In June 2014, we collected samples at different depths from a snow profile at the Jungfraujoch (Swiss Alps; 3621 m a.s.l.. After filtration, we performed various microbiological and physicochemical analyses of the snow and dust particles therein that originated in Algeria.Our results show that bacteria survive and are metabolically active after the transport to the European Alps. Using high throughput sequencing, we observed distinct differences in bacterial community composition and structure in SD-layers as compared to clean snow layers. Sporulating bacteria were not enriched in the SD-layers; however, phyla with low abundance such as Gemmatimonadetes and Deinococcus-Thermus appeared to be specific bio-indicators for SD. Since many members of these phyla are known to be adapted to arid oligotrophic environments and UV radiation, they are well suited to survive the harsh conditions of long-range airborne transport.

  14. Hsp20, a small heat shock protein of Deinococcus radiodurans, confers tolerance to hydrogen peroxide in Escherichia coli.

    Science.gov (United States)

    Singh, Harinder; Appukuttan, Deepti; Lim, Sangyong

    2014-08-01

    The present study shows that DR1114 (Hsp20), a small heat shock protein of the radiationresistant bacterium Deinococcus radiodurans, enhances tolerance to hydrogen peroxide (H2O2) stress when expressed in Escherichia coli. A protein profile comparison showed that E. coli cells overexpressing D. radiodurans Hsp20 (EC-pHsp20) activated the redox state proteins, thus maintaining redox homeostasis. The cells also showed increased expression of pseudouridine (psi) synthases, which are important to the stability and proper functioning of structural RNA molecules. We found that the D. radiodurans mutant strain, which lacks a psi synthase (DR0896), was more sensitive to H2O2 stress than wild type. These suggest that an increased expression of proteins involved in the control of redox state homeostasis along with more stable ribosomal function may explain the improved tolerance of EC-pHsp20 to H2O2 stress.

  15. The abundant and essential HU proteins in Deinococcus deserti and Deinococcus radiodurans are translated from leaderless mRNA.

    Science.gov (United States)

    Bouthier de la Tour, Claire; Blanchard, Laurence; Dulermo, Rémi; Ludanyi, Monika; Devigne, Alice; Armengaud, Jean; Sommer, Suzanne; de Groot, Arjan

    2015-12-01

    HU proteins have an important architectural role in nucleoid organization in bacteria. Compared with HU of many bacteria, HU proteins from Deinococcus species possess an N-terminal lysine-rich extension similar to the eukaryotic histone H1 C-terminal domain involved in DNA compaction. The single HU gene in Deinococcus radiodurans, encoding DrHU, is required for nucleoid compaction and cell viability. Deinococcus deserti contains three expressed HU genes, encoding DdHU1, DdHU2 and DdHU3. Here, we show that either DdHU1 or DdHU2 is essential in D. deserti. DdHU1 and DdHU2, but not DdHU3, can substitute for DrHU in D. radiodurans, indicating that DdHU3 may have a non-essential function different from DdHU1, DdHU2 and DrHU. Interestingly, the highly abundant DrHU and DdHU1 proteins, and also the less expressed DdHU2, are translated in Deinococcus from leaderless mRNAs, which lack a 5'-untranslated region and, hence, the Shine-Dalgarno sequence. Unexpectedly, cloning the DrHU or DdHU1 gene under control of a strong promoter in an expression plasmid, which results in leadered transcripts, strongly reduced the DrHU and DdHU1 protein level in D. radiodurans compared with that obtained from the natural leaderless gene. We also show that the start codon position for DrHU and DdHU1 should be reannotated, resulting in proteins that are 15 and 4 aa residues shorter than initially reported. The expression level and start codon correction were crucial for functional characterization of HU in Deinococcus.

  16. Deinococcus metallilatus sp. nov. and Deinococcus carri sp. nov., isolated from a car air-conditioning system.

    Science.gov (United States)

    Kim, Dong-Uk; Lee, Hyosun; Lee, Ji-Hyeong; Ahn, Jae-Hyung; Lim, Sangyong; Jeong, Sunwook; Park, So Yoon; Seong, Chi Nam; Ka, Jong-Ok

    2015-09-01

    Two bacterial strains, designated MA1002(T) and MA1003(T), were isolated from the air-conditioning system of a car. Cells of both strains were Gram-reaction-positive, non-motile, non-spore-forming coccoids, catalase- and oxidase-positive and UV-radiation resistant. The major fatty acids of strain MA1002(T) were iso-C17 : 0 and iso-C15 : 0 and those of strain MA1003(T) were iso-C16 : 0 and iso-C16 : 1 H. The polar lipid profile of MA1002(T) contained phosphatidylethanolamine, two unidentified phosphoglycolipids, an unidentified phospholipid, an unidentified aminophospholipid, an unidentified aminolipid and an unidentified lipid. MA1003(T) had three unidentified phosphoglycolipids, six unidentified phospholipids, two unidentified glycolipids and two unidentified polar lipids as the polar lipids. The G+C contents of the genomic DNA of MA1002(T) and MA1003(T) were 70.5 and 76.0 mol%, respectively. MK-8 was the predominant respiratory quinone for both strains. 16S rRNA gene sequence analysis showed that strain MA1002(T) was phylogenetically related to Deinococcus apachensis DSM 19763(T), D. geothermalis DSM 11300(T), D. aerius TR0125(T) and D. aetherius ST0316(T) (92.9, 92.6, 92.0 and 91.9% sequence similarity, respectively), and MA1003(T) showed the highest sequence similarity to Deinococcus hopiensis KR-140(T) (92.9%) and D. xinjiangensis X-82(T) (91.4%). The results of genotypic and phenotypic characterizations showed that both strains could be distinguished from phylogenetically related species, and that the strains represented novel species within the genus Deinococcus, for which we propose the names Deinococcus metallilatus sp. nov. (type strain MA1002(T) = KACC 17964(T) = NBRC 110141(T)) and Deinococcus carri sp. nov. (type strain is MA1003(T) = KACC 17965(T) = NBRC 110142(T)).

  17. Effects of Deinococcus spp. supplement on egg quality traits in laying hens.

    Science.gov (United States)

    Li, I-Chen; Wu, Szu-Yin; Liou, Jenn-Fa; Liu, Hsiao-Hui; Chen, Jiau-Hua; Chen, Chin-Chu

    2017-10-25

    To counter the ill effects of synthetic dyes, bacterial pigment production as an alternative is now one of the promising and emerging fields of research. This study was conducted to evaluate the applicability of Deinococcus genus on the egg quality traits in laying hens. In study I, 24 single comb White Leghorn layers were fed with various 1 wt % Deinococcus bacterial strains for 10 d. In study II, 84 brown Hendrix layers were fed with one of 4 diets containing 0, 0.2, 1, or 5 wt % Deinococcus sp. GKB-Aid 1995 powder for 12 wk. In study III, 60 White Leghorn laying hens were fed either with or without 1 wt % Deinococcus sp. GKB-Aid 1995 powder, 1 wt % Deinococcus sp. GKB-Aid 1995 granules, or 1 wt % Deinococcus sp. GKB-Aid 1995 oily granules for 10 successive d. In all of the experiments, feeding Deinococcus powder did not affect egg quality traits except for the yolk color. In particular, supplementation with all Deinococcus powder treatments changed the yolk color (P < 0.05) in study I, with the best pigmentation score obtained by D. grandis and Deinococcus sp. GKB-Aid 1995. Moreover, longer supplementation of Deinococcus sp. GKB-Aid 1995 in study II had a significant effect on feed conversion ratio. With these findings under consideration, the present study suggests that the Deinococcus species, especially Deinococcus sp. GKB-Aid 1995, can be an excellent candidate for improving egg yolk color in laying hens. © 2017 Poultry Science Association Inc.

  18. The effect of Mn(II) on the autoinducing growth inhibition factor in Deinococcus radiodurans.

    Science.gov (United States)

    Lee, Hui-Yu; Wong, Tit-Yee; Kuo, Jimmy; Liu, Jong-Kang

    2014-10-03

    Decreases in cell division at the stationary phase in bacterial cultures are often due to the depletion of nutrients and/or accumulation of toxic waste products. Yet, during the stationary phase, the highly radiation-resistant bacterium Deinococcus radiodurans undergoes new rounds of cell division when Mn(II) is added to the medium in a phenomenon known as manganese-induced cell division (MnCD). When cells were cultured in medium without Mn(II)-enrichment, a heat-resistant, proteinase K-resistant factor (or factors) with a molecular mass less than 10 kD accumulated in the spent medium. Inclusion of the concentrated spent medium in fresh medium could inhibit the growth of D. radiodurans significantly, and the degree of inhibition was dose dependent. However, the relative stimulatory effect of MnCD was also dose dependent-the higher the inhibition, the stronger was the MnCD response. Previous studies have shown that nutrients were not limiting and deinococcal cells would continue metabolizing its nutrients at stationary phase. Cells became more sensitive to radiation when nutrients in the medium eventually became depleted. We speculated that D. radiodurans might produce this factor in the medium to control its population density. The reduction in cell population would conserve the nutrients that in turn might enhance the survival of the species.

  19. Enhanced stress resistance of Deinococcus radiodurans cells in the dried state

    Science.gov (United States)

    Bauermeister, Anja; Moeller, Ralf; Reitz, Guenther; Billi, Daniela; Rettberg, Petra

    Liquid water is often regarded as a pre-requisite for life as we know it. However, some organisms can survive prolonged periods in a desiccated state and seem to resist other environmental stres-sors even better when water is absent. We tested this observation in Deinococcus radiodurans, a non-sporeforming soil bacterium well-known for its outstanding resistance to DNA damaging stressors, including high doses of UV and ionizing radiation, oxidants, and desiccation. Due to its polyextremophilic characteristics it has been regarded as a model organism in astrobiological research. To determine if the cellular changes imposed by the removal of water have an effect on the stress resistance of D. radiodurans, we compared the survival capacity of dried cells with that of hydrated cells after exposure to mono-and polychromatic UV radiation, -radiation, and heat shock (85C). In all cases, resistance was enhanced in dried cells. It is suggested that these effects are mainly due to a reduced oxidative stress in dried cells, as the metabolism is shut down and radical diffusion is very limited. Hence, desiccating conditions as encountered in space vacuum or on arid planets such as Mars may be beneficial instead of detrimental to the survival of some polyextremophilic microbes. Ongoing experiments aim to evaluate damage at a subcellular level in dried and hydrated cells after exposure to irradiation or heat shock.

  20. Phosphorylation of Deinococcus radiodurans RecA Regulates Its Activity and May Contribute to Radioresistance.

    Science.gov (United States)

    Rajpurohit, Yogendra S; Bihani, Subhash C; Waldor, Matthew K; Misra, Hari S

    2016-08-05

    Deinococcus radiodurans has a remarkable capacity to survive exposure to extreme levels of radiation that cause hundreds of DNA double strand breaks (DSBs). DSB repair in this bacterium depends on its recombinase A protein (DrRecA). DrRecA plays a pivotal role in both extended synthesis-dependent strand annealing and slow crossover events of DSB repair during the organism's recovery from DNA damage. The mechanisms that control DrRecA activity during the D. radiodurans response to γ radiation exposure are unknown. Here, we show that DrRecA undergoes phosphorylation at Tyr-77 and Thr-318 by a DNA damage-responsive serine threonine/tyrosine protein kinase (RqkA). Phosphorylation modifies the activity of DrRecA in several ways, including increasing its affinity for dsDNA and its preference for dATP over ATP. Strand exchange reactions catalyzed by phosphorylated versus unphosphorylated DrRecA also differ. In silico analysis of DrRecA structure support the idea that phosphorylation can modulate crucial functions of this protein. Collectively, our findings suggest that phosphorylation of DrRecA enables the recombinase to selectively use abundant dsDNA substrate present during post-irradiation recovery for efficient DSB repair, thereby promoting the extraordinary radioresistance of D. radiodurans. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Expression, purification, crystallization and preliminary X-ray diffraction analysis of acylpeptide hydrolase from Deinococcus radiodurans.

    Science.gov (United States)

    Are, Venkata Narayana; Ghosh, Biplab; Kumar, Ashwani; Yadav, Pooja; Bhatnagar, Deepak; Jamdar, Sahayog N; Makde, Ravindra D

    2014-09-01

    Acylpeptide hydrolase (APH; EC 3.4.19.1), which belongs to the S9 family of serine peptidases (MEROPS), catalyzes the removal of an N-acylated amino acid from a blocked peptide. The role of this enzyme in mammalian cells has been suggested to be in the clearance of oxidatively damaged proteins as well as in the degradation of the β-amyloid peptides implicated in Alzheimer's disease. Detailed structural information for the enzyme has been reported from two thermophilic archaea; both of the archaeal APHs share a similar monomeric structure. However, the mechanisms of substrate selectivity and active-site accessibility are totally different and are determined by inter-domain flexibility or the oligomeric structure. An APH homologue from a bacterium, Deinococcus radiodurans (APHdr), has been crystallized using microbatch-under-oil employing the random microseed matrix screening method. The protein crystallized in space group P21, with unit-cell parameters a = 77.6, b = 189.6, c = 120.4 Å, β = 108.4°. A Matthews coefficient of 2.89 Å(3) Da(-1) corresponds to four monomers, each with a molecular mass of ∼73 kDa, in the asymmetric unit. The APHdr structure will reveal the mechanisms of substrate selectivity and active-site accessibility in the bacterial enzyme. It will also be helpful in elucidating the functional role of this enzyme in D. radiodurans.

  2. Autoinducer-2 signaling is involved in regulation of stress-related genes of Deinococcus radiodurans.

    Science.gov (United States)

    Lin, Lin; Li, Tao; Dai, Shang; Yu, Jiangliu; Chen, Xiuqin; Wang, Liangyan; Wang, Yunguang; Hua, Yuejin; Tian, Bing

    2016-01-01

    Autoinducer-2 (AI-2) serves as a quorum-sensing signaling molecule that mediates both intraspecies and interspecies communication among bacteria, and plays critical roles in regulating various bacterial behaviors. In the present study, we investigated the functions of AI-2 signaling in the extremophilic bacterium Deinococcus radiodurans R1 by construction of the LuxS gene disruption mutant, survival phenotype assay and gene transcription assay. The gene mutant (DRΔLuxS), which was unable to produce AI-2, was significantly more sensitive to both gamma radiation and H2O2 compared with the wild-type strain. Addition of the wild-type-derived spent medium into the cell culture of DRΔLuxS fully restored the radioresistance of D. radiodurans. A higher level of reactive oxygen species accumulated in the mutant compared with the wild type under normal or oxidative stress. Quantitative real-time PCR assays showed that transcriptional levels of stress-related proteins, including catalase, extracellular nuclease, Dps-1 and ABC transporters, were decreased in DRΔLuxS, indicating that AI-2 is involved in regulation of stress-related genes of D. radiodurans. Hence, AI-2 signaling may contribute to the extreme resistance of D. radiodurans to radiation and oxidative stresses.

  3. Simulation of the Martian UV radiation climate and its effect on Deinococcus radiodurans

    Science.gov (United States)

    Pogoda de La Vega, U.; Rettberg, P.

    The question of putative life on Mars has been the topic of several studies Early works had to rely on the physical data that have been gained during the 1970s with the help of the Viking missions More recently several Mars-related missions have provided numerous and more precise data to establish a realistic simulation of the Martian climate Our focus is directed at the diurnal temperature variations and the atmospheric pressure and composition the so called thermo-physical conditions which are typical for the Martian mid- and low latitudes The resistance of terrestrial microorganisms under the thermo-physical conditions on Mars was studied for the understanding and assessment of potential life processes on Mars In order to accomplish a targeted search for life on other planets e g Mars it is necessary to know the limiting physical and chemical parameters of terrestrial life Therefore the polyextremophile bacterium Deinococcus radiodurans was chosen as test organism for these investigations For the simulation studies at the Planetary and Space Simulation Facilities PSI at DLR Cologne Germany conditions that are present during the southern summer at latitude of 60 r on Mars were applied We could simulate several environmental parameters of Mars vacuum low pressure anoxic atmosphere and diurnal cycles in temperature energy-rich UV radiation as well as shielding by different Martian soil analogue materials These parameters have been applied both single and in different combinations in laboratory experiments

  4. The essential role of the Deinococcus radiodurans ssb gene in cell survival and radiation tolerance.

    Science.gov (United States)

    Lockhart, J Scott; DeVeaux, Linda C

    2013-01-01

    Recent evidence has implicated single-stranded DNA-binding protein (SSB) expression level as an important factor in microbial radiation resistance. The genome of the extremely radiation resistant bacterium Deinococcus radiodurans contains genes for two SSB homologs: the homodimeric, canonical Ssb, encoded by the gene ssb, and a novel pentameric protein encoded by the gene ddrB. ddrB is highly induced upon exposure to radiation, and deletions result in decreased radiation-resistance, suggesting an integral role of the protein in the extreme resistance exhibited by this organism. Although expression of ssb is also induced after irradiation, Ssb is thought to be involved primarily in replication. In this study, we demonstrate that Ssb in D. radiodurans is essential for cell survival. The lethality of an ssb deletion cannot be complemented by providing ddrB in trans. In addition, the radiation-sensitive phenotype conferred by a ddrB deletion is not alleviated by providing ssb in trans. By altering expression of the ssb gene, we also show that lower levels of transcription are required for optimal growth than are necessary for high radiation resistance. When expression is reduced to that of E. coli, ionizing radiation resistance is similarly reduced. UV resistance is also decreased under low ssb transcript levels where growth is unimpaired. These results indicate that the expression of ssb is a key component of both normal cellular metabolism as well as pathways responsible for the high radiation tolerance of D. radiodurans.

  5. Expression, purification and crystallization of two endonuclease III enzymes from Deinococcus radiodurans.

    Science.gov (United States)

    Sarre, Aili; Ökvist, Mats; Klar, Tobias; Moe, Elin; Timmins, Joanna

    2014-12-01

    Endonuclease III is a bifunctional DNA glycosylase that removes a wide range of oxidized bases in DNA. Deinococcus radiodurans is an extreme radiation-resistant and desiccation-resistant bacterium and possesses three genes encoding endonuclease III enzymes in its genome: DR2438 (EndoIII-1), DR0289 (EndoIII-2) and DR0982 (EndoIII-3). Here, EndoIII-1 and an N-terminally truncated form of EndoIII-3 (EndoIII-3Δ76) have been expressed, purified and crystallized, and preliminary X-ray crystallographic analyses have been performed to 2.15 and 1.31 Å resolution, respectively. The EndoIII-1 crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 181.38, b = 38.56, c = 37.09 Å, β = 89.34° and one molecule per asymmetric unit. The EndoIII-3Δ76 crystals also belonged to the monoclinic space group C2, but with unit-cell parameters a = 91.47, b = 40.53, c = 72.47 Å, β = 102.53° and one molecule per asymmetric unit. The EndoIII-1 structure was determined by molecular replacement, while the truncated EndoIII-3Δ76 structure was determined by single-wavelength anomalous dispersion phasing. Refinement of the structures is in progress.

  6. Involvement of recQ in the ultraviolet damage repair pathway in Deinococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Hua Xiaoting [Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Kaixuan RD 268, Hangzhou, Zhejiang 310029 (China); Huang Lifen [Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Kaixuan RD 268, Hangzhou, Zhejiang 310029 (China)]|[Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou 225009 (China); Tian Bing [Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Kaixuan RD 268, Hangzhou, Zhejiang 310029 (China); Hua Yuejin [Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Kaixuan RD 268, Hangzhou, Zhejiang 310029 (China)], E-mail: yjhua@zju.edu.cn

    2008-05-10

    Deinococcus radiodurans is a bacterium which can survive extremely DNA damage. To investigate the relationship between recQ and the ultraviolet radiation (UV) damage repair pathway, we created a four mutant strain by constructing recQ knockout mutants in uvrA1, uvrA2, and uvsE backgrounds. Using the rpoB/Rif{sup r} system, we measured the mutation frequencies and rates in wild type, recQ (MQ), uvsE uvrA1 uvrA2 (TNK006), and uvsE uvrA1 uvrA2 recQ (TQ). We then isolated Rif{sup r} mutants of these strains and sequenced the rpoB gene. The mutation frequency of TQ was 6.4, 10.1, and 2.43 times that of wild type, MQ, and TNK006, respectively, and resulted in rates of 4.7, 6.71, and 2.15 folds higher than that of wild type, MQ, and TNK006, respectively. All the strains demonstrated specific mutational hotspots. Furthermore, the TQ strain showed a transversion bias that was different from the other three strains. The results indicate that recQ is involved in the ultraviolet damage repair pathway via the interaction between recQ and uvrA1, uvrA2, and uvsE in D. radiodurans.

  7. Phosphorylation of Deinococcus radiodurans RecA Regulates Its Activity and May Contribute to Radioresistance*

    Science.gov (United States)

    Rajpurohit, Yogendra S.; Bihani, Subhash C.; Waldor, Matthew K.; Misra, Hari S.

    2016-01-01

    Deinococcus radiodurans has a remarkable capacity to survive exposure to extreme levels of radiation that cause hundreds of DNA double strand breaks (DSBs). DSB repair in this bacterium depends on its recombinase A protein (DrRecA). DrRecA plays a pivotal role in both extended synthesis-dependent strand annealing and slow crossover events of DSB repair during the organism's recovery from DNA damage. The mechanisms that control DrRecA activity during the D. radiodurans response to γ radiation exposure are unknown. Here, we show that DrRecA undergoes phosphorylation at Tyr-77 and Thr-318 by a DNA damage-responsive serine threonine/tyrosine protein kinase (RqkA). Phosphorylation modifies the activity of DrRecA in several ways, including increasing its affinity for dsDNA and its preference for dATP over ATP. Strand exchange reactions catalyzed by phosphorylated versus unphosphorylated DrRecA also differ. In silico analysis of DrRecA structure support the idea that phosphorylation can modulate crucial functions of this protein. Collectively, our findings suggest that phosphorylation of DrRecA enables the recombinase to selectively use abundant dsDNA substrate present during post-irradiation recovery for efficient DSB repair, thereby promoting the extraordinary radioresistance of D. radiodurans. PMID:27255712

  8. Impact of low-temperature plasmas on Deinococcus radiodurans and biomolecules

    Science.gov (United States)

    Mogul, Rakesh; Bol'shakov, Alexander A.; Chan, Suzanne L.; Stevens, Ramsey M.; Khare, Bishun N.; Meyyappan, M.; Trent, Jonathan D.

    2003-01-01

    The effects of cold plasma on Deinococcus radiodurans, plasmid DNA, and model proteins were assessed using microbiological, spectrometric, and biochemical techniques. In low power O(2) plasma (approximately 25 W, approximately 45 mTorr, 90 min), D. radiodurans, a radiation-resistant bacterium, showed a 99.999% reduction in bioburden. In higher power O(2) plasma (100 W and 500 mTorr), the reduction rate increased about 10-fold and observation by atomic force microscopy showed significant damage to the cell. Damage to cellular lipids, proteins, and chromosome was indicated by losses of infrared spectroscopic peaks at 2930, 1651, 1538, and 1245 cm(-1), respectively. In vitro experiments show that O(2) plasmas induce DNA strand scissions and cross-linking as well as reduction of enzyme activity. The observed degradation and removal of biomolecules was power-dependent. Exposures to 200 W at 500 mTorr removed biomolecules to below detection limits in 60 s. Emission spectroscopy indicated that D. radiodurans cells were volatilized into CO(2), CO, N(2), and H(2)O, confirming that these plasmas were removing complex biological matter from surfaces. A CO(2) plasma was not as effective as the O(2) plasma, indicating the importance of plasma composition and the dominant role of chemical degradation. Together, these findings have implications for NASA planetary protection schemes and for the contamination of Mars.

  9. The essential role of the Deinococcus radiodurans ssb gene in cell survival and radiation tolerance.

    Directory of Open Access Journals (Sweden)

    J Scott Lockhart

    Full Text Available Recent evidence has implicated single-stranded DNA-binding protein (SSB expression level as an important factor in microbial radiation resistance. The genome of the extremely radiation resistant bacterium Deinococcus radiodurans contains genes for two SSB homologs: the homodimeric, canonical Ssb, encoded by the gene ssb, and a novel pentameric protein encoded by the gene ddrB. ddrB is highly induced upon exposure to radiation, and deletions result in decreased radiation-resistance, suggesting an integral role of the protein in the extreme resistance exhibited by this organism. Although expression of ssb is also induced after irradiation, Ssb is thought to be involved primarily in replication. In this study, we demonstrate that Ssb in D. radiodurans is essential for cell survival. The lethality of an ssb deletion cannot be complemented by providing ddrB in trans. In addition, the radiation-sensitive phenotype conferred by a ddrB deletion is not alleviated by providing ssb in trans. By altering expression of the ssb gene, we also show that lower levels of transcription are required for optimal growth than are necessary for high radiation resistance. When expression is reduced to that of E. coli, ionizing radiation resistance is similarly reduced. UV resistance is also decreased under low ssb transcript levels where growth is unimpaired. These results indicate that the expression of ssb is a key component of both normal cellular metabolism as well as pathways responsible for the high radiation tolerance of D. radiodurans.

  10. Preserving genome integrity: the DdrA protein of Deinococcus radiodurans R1.

    Directory of Open Access Journals (Sweden)

    Dennis R Harris

    2004-10-01

    Full Text Available The bacterium Deinococcus radiodurans can withstand extraordinary levels of ionizing radiation, reflecting an equally extraordinary capacity for DNA repair. The hypothetical gene product DR0423 has been implicated in the recovery of this organism from DNA damage, indicating that this protein is a novel component of the D. radiodurans DNA repair system. DR0423 is a homologue of the eukaryotic Rad52 protein. Following exposure to ionizing radiation, DR0423 expression is induced relative to an untreated control, and strains carrying a deletion of the DR0423 gene exhibit increased sensitivity to ionizing radiation. When recovering from ionizing-radiation-induced DNA damage in the absence of nutrients, wild-type D. radiodurans reassembles its genome while the mutant lacking DR0423 function does not. In vitro, the purified DR0423 protein binds to single-stranded DNA with an apparent affinity for 3' ends, and protects those ends from nuclease degradation. We propose that DR0423 is part of a DNA end-protection system that helps to preserve genome integrity following exposure to ionizing radiation. We designate the DR0423 protein as DNA damage response A protein.

  11. Sec pathway influences the growth of Deinococcus radiodurans.

    Science.gov (United States)

    Wang, Liangyan; Tan, Hongmei; Cheng, Kaiying; Li, Mingfeng; Xu, Xin; Wang, Jing; Hua, Yuejin

    2015-05-01

    The release of extracellular DNA molecules (eDNA) contributes to various biological processes, such as biofilm formation, virulence, and stress tolerance. The quantity of eDNA released by bacteria is usually regulated by extracellular nucleases that are secreted by different systems. In this study, we show that high concentrations of eDNA inhibit the growth of two strains of Deinococcaceae, Deinococcus radiodurans, and Deinococcus radiopugnans, but have no effect on other selected organisms, such as Escherichia coli. In D. radiodurans, an extracellular nuclease was shown to be secreted through the Sec pathway. Disruption of one member of this pathway, SecD/F, inhibited cell growth, suggesting that the Sec pathway plays an important role in growth rate. However, the Sec pathway mutant exhibited a greater deficiency in growth rate compared with the extracellular nuclease mutant, indicating that the pathway not only secretes the extracellular nuclease, but has other unknown functions as well.

  12. X-ray imaging of radioresistant Deinococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Takemoto, K; Kihara, H [Department of Physics, Kansai Medical University, 18-89 Uyamahigashi, Hirakata, Osaka, 573-1136 (Japan); Narumi, I; Satoh, K [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, 370-1292 (Japan); Namba, H, E-mail: takemoto@makino.kmu.ac.j [Department of Physical Science, Ritsumeikan University, 1-1-1 Noji-Higashi Kusatsu, Shiga, 525-8577 (Japan)

    2009-09-01

    Deinococcus radiodurans has been known to withstand radiation levels up to 1,000 times than that would kill normal human cells. To cope radiation damage during soft X-ray observation of living cells, D. radiodurans incubated with tellurium oxyanions was used as the X-ray microscopy sample. The first observation was successfully performed. In combination of antifreeze solution and subzero temperature, along with carbon window, the cell observation will be more closely to the living condition.

  13. ATCG nucleotide fluctuation of Deinococcus radiodurans radiation genes

    Science.gov (United States)

    Holden, Todd; Subramaniam, R.; Sullivan, R.; Cheung, E.; Schneider, C.; Tremberger, G., Jr.; Flamholz, A.; Lieberman, D. H.; Cheung, T. D.

    2007-09-01

    The radiation resistance-repair genes in Deinococcus radiodurans (DR) and E-coli were analyzed in terms of the A, T, C, G nucleotide fluctuations. The studied genes were Rec-A, Rec-Q, and the unique DR PprA gene. In an ATCG sequence, each base was assigned a number equal to its atomic number. The resulting numerical sequence was the basis of the statistical analysis. Fractal analysis using the Higuchi method gave a fractal dimension increase of the Deinococcus radiodurans genes as compared to E-coli, which is comparable to the enhancement observed in the human HAR1 region (HAR1F gene) over that of the chimpanzee. Near neighbor fluctuation was also studied via the Black-Scholes model where the increment sequence was treated as a random walk series. The Deinococcus radiodurans radiation gene standard deviations were consistently higher than that of the E-coli deviations, and agree with the fractal analysis results. The sequence stacking interaction was studied using the published nucleotide-pair melting free energy values and Deinococcus radiodurans radiation genes were shown to possess larger negative free energies. The high sensitivity of the fractal dimension as a biomarker was tested with correlation analysis of the gamma ray dose versus fractal dimension, and the R square values were found to be above 0.9 (N=5). When compared with other nucleotide sequences such as the rRNA sequences, HAR1 and its chimpanzee counterpart, the higher fluctuation (correlated randomness) and larger negative free energy of a DR radiation gene suggested that a radiation resistance-repair sequence exhibited higher complexity. As the HAR1 nucleotide sequence complexity and its transcription activity of co-expressing cortex protein reelin supported a positive selection event in humans, a similar inference of positive selection of coding genes could be drawn for Deinococcus radiodurans when compared to E-coli. The origin of such a positive selection would be consistent with that of a

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    When crossing the Sahara it was expected that nocturnal migrants would continue their flight into the day. We investigated whether migration taking place in the Sahara during daytime comprises the normal diurnal migrant species or the nocturnal ones prolonging their flight into the day. Birds departing from the Sahel in ...

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    South of Sahara. Sud du Sahara. Read more about Rainwater and Greywater Harvesting in Urban and Periurban Agriculture in Ariana-Soukra (Tunisia). Language English. Read more about Récupération des eaux grises et des eaux pluviales pour l'agriculture urbaine et périurbaine à La Soukra, dans le gouvernorat ...

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    South of Sahara. Sud du Sahara. Read more about Approfondissement des connaissances et renforcement des capacités en matière de sexospécificités au sein du programme ACACIA. Language French. Read more about Acacia Gender Learning and Capacity Strengthening. Language English. Read more about Soutien ...

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    South of Sahara. Sud du Sahara. Read more about Transition de Bellanet. Language French. Read more about Le coût des conflits dans la zone du Marché commun de l'Afrique orientale et australe (COMESA). Language French. Read more about Cost of Conflicts in the Common Market for Eastern and Southern Africa ...

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    South of Sahara. Sud du Sahara. Read more about Economic Research Forum - Core Support 2012-2014. Language English. Read more about Forum de recherche économique - Financement de base 2012-2014. Language French. Read more about Reducing Vulnerability to Sexual and Gender-Based Violence in ...

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    South of Sahara. Sud du Sahara. Read more about Compliance with Private Food Safety Standards among Smallholders in Kenya. Language English. Read more about Respect des normes de salubrité des aliments privées chez les petits exploitants agricoles du Kenya. Language French. Read more about Stimulation de ...

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    South of Sahara. Sud du Sahara. Read more about Renforcement des connaissances économiques et de la capacité d'adaptation face aux changements climatiques au Bénin. Language French. Read more about Strengthening Economic Skills and Climate Change Adaptive Capacity in Bénin. Language English.

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    South of Sahara. Sud du Sahara. Read more about Changements climatiques et santé des autochtones. Language French. Read more about Strengthening Equity through Applied Research Capacity Building in e-Health. Language English. Read more about La législation sur le salaire minimum, son application et la ...

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    South of Sahara. Sud du Sahara. Read more about Nouveau télécentre de Manhiça (Mozambique). Language French. Read more about New Premises Assistance : Manhica Telecentre Association (Mozambique). Language English. Read more about Health Risk Analysis of Cryptosporidiosis and other Hazards in Urban ...

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    South of Sahara. Sud du Sahara. Read more about Suivi de structures criminelles dans des villes africaines. Language French. Read more about Universities in Innovation for Inclusive Development: Africa. Language English. Read more about How to access funding for non-communicable disease prevention in Africa?

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    South of Sahara. Sud du Sahara. Read more about Savoir émergent - suivi de la progression vers la société de l'information. Language French. Read more about Monitoring Progress Toward the Information Society : Digital Divide Index. Language English. Read more about Lake Naivasha Sustainability : Ecosystem ...

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    South of Sahara. Sud du Sahara. Read more about La protection des renseignements personnels dans l'hémisphère sud (Protecting Privacy in the Global South) - Phase 2. Language French. Read more about Doctoral Awards to Strengthen Sub-Saharan Africa Leadership in HIV Prevention Research. Language English.

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    South of Sahara. Sud du Sahara. Read more about Open Architecture, Standards and Information Systems (OASIS) for Healthcare in Africa. Language English. Read more about Gestion intégrée de l'eau, de l'assainissement et des déchets solides dans de petits centres urbains autour du lac Victoria (Kenya). Language ...

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    South of Sahara. Sud du Sahara. Read more about Cigarette Taxation in Tanzania. Language English. Read more about Vers une structure de sécurité régionale dans la Corne de l'Afrique - phase II. Language French. Read more about Toward a Regional Security Architecture for the Horn of Africa - Phase II. Language ...

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    South of Sahara. Sud du Sahara. Read more about Integrated Intervention for Diabetes Risk After Gestational Diabetes in South Africa. Language English. Read more about Essais cliniques d'un vaccin expérimental contre le virus Ebola : une intervention canadienne dans la recherche. Language French. Read more about ...

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    South of Sahara. Sud du Sahara. Read more about Tobacco Taxation, Smuggling, and Street Tobacco Vendors in Eritrea. Language English. Read more about Taxes sur le tabac, contrebande et vendeurs de rue en Érythrée. Language French. Read more about The Role of Militia, Predatory State Authorities, and Rogue ...

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    South of Sahara. Sud du Sahara. Read more about Innovation pharmaceutique, délivrance de brevets sur des variantes mineures et licences obligatoires. Language French. Read more about Pharmaceutical Innovation, Incremental Patenting and Compulsory Licensing. Language English. Read more about Vers une ...

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    South of Sahara. Sud du Sahara. Read more about Renforcement des stratégies locales de gestion des zones sylvo-pastorales inter villageoises dans le basin arachidier du Sénégal. Language French. Read more about Strengthening Local Strategies for Managing Inter Village Agro-pastoral Resources in the Groundnut ...

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    South of Sahara. Sud du Sahara. Read more about Gestion des milieux humides en vue d'une plus grande sécurité alimentaire en Ouganda. Language French. Read more about Minimum Wage Legislation, Enforcement and Labour Outcomes in Argentina, Costa Rica and South Africa. Language English. Read more ...

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    South of Sahara. Sud du Sahara. Read more about Managing Climate Risk to Agriculture and Water Resources in South Africa. Language English. Read more about Études par pays dans le cadre du HIV/AIDS Monitor. Language French. Read more about HIV/AIDS Monitor Country Studies. Language English. Read more ...

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    South of Sahara. Sud du Sahara. Read more about Renforcement des capacités en Afrique en matière d'indicateurs de S-T et d'innovation. Language French. Read more about Building African Capacity in Science, Technology and Innovation Indicators. Language English. Read more about Transfert du modèle prédictif ...

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    South of Sahara. Sud du Sahara. Read more about La protection sociale et les collectivités vulnérables en Afrique de l'Est - retombées sur le bien-être des ménages. Language French. Read more about Social Protection and Vulnerable Communities in East Africa: Implications for Household Welfare. Language English.

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    South of Sahara. Sud du Sahara. Read more about Building a Community ICT Network in Mozambique. Language English. Read more about Appui au réseautage et au renforcement des télécentres communautaires au Mali. Language French. Read more about Support for Community Telecentres and Networks in Mali.

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    South of Sahara. Sud du Sahara. Read more about Reducing Vulnerability to Sexual and Gender-Based Violence in Kenya. Language English. Read more about Gestion des risques, réduction de la vulnérabilité et accroissement de la productivité dans un contexte de changements climatiques. Language French.

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    South of Sahara. Sud du Sahara. Read more about Five-City Network to Pioneer Climate Change Adaptation in sub-Saharan Africa. Language English. Read more about Protection de la communauté urbaine de Cotonou face aux changements climatiques (Bénin). Language French. Read more about Protecting the Urban ...

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    South of Sahara. Sud du Sahara. Read more about Acacia Gender Learning and Capacity Strengthening. Language English. Read more about Approfondissement des connaissances et renforcement des capacités en matière de sexospécificités au sein du programme ACACIA. Language French. Read more about Soutien ...

  8. No Otters in the Tassili Mountains (Sahara)

    OpenAIRE

    Smet K. de

    1987-01-01

    The Tassill Mountains are situated in the centre of the Sahara Desert and as they are rather high (summits over 2,000 m), they have a rainfall of more than 50 mm/year. There are many rivers in these mountains and although they only flow after the occasional rains, a great number of small lakes (locally called Guelta) remain in the deep canyons. Some river systems always have running water (Oued Imirhou, Oued Iherir) and most of them contain large quantities of fish (Barbus sp., Tilapia sp.) ...

  9. The Late Miocene climate response to a modern Sahara desert

    Science.gov (United States)

    Micheels, Arne; Eronen, Jussi; Mosbrugger, Volker

    2009-06-01

    The climate cooling and vegetation changes in the Miocene/Pliocene are generally well documented by various proxy data. Some important ecosystem changes occurred at that time. Palaeobotanical evidence suggests that the Sahara desert first appeared in the Pliocene, whereas in the Miocene North Africa was green. In the present study, we investigate the Late Miocene climate response to the appearance of the Sahara desert from a climate modelling sensitivity experiment. We compare a model experiment, which includes a full set of Late Miocene boundary conditions, with another one using the same boundary conditions except that the North African vegetation refers to the present-day situation. Our sensitivity study demonstrates that the introduction of the Sahara desert leads to a cooling and an aridification in Africa. In addition, we observe teleconnection patterns related to the North African desertification at around the Miocene/Pliocene boundary. From our sensitivity experiment, we observe that the Sahara contributes to a cooling in Central Asia and in North America. As compared to hypsodonty data for Central Asia, an increased aridity is underestimated in the Sahara experiment. Finally, we observe that the introduction of the Sahara leads to a cooling in the northern high latitudes. Hence, our sensitivity experiment indicates that the appearance of the Sahara desert is one piece to better understand Late Cenozoic climate cooling being most pronounced in the high latitudes.

  10. A New Perspective on Radiation Resistance Based on Deinococcus radiodurans

    Science.gov (United States)

    2009-03-01

    Deinococcus radiodurans Halobacterium sp. NRC-1 Enterococcus faecium Thermus thermophilus Escherichia coli Pseudomonas putida Neisseria gonorrhoeae...Halobacterium (Archaeon) E. faecium D. geothermalis from the indirect effects of IR (BOX 1) is sur‑ vival ultimately determined by the level of DNA damage12...survival (kGy) E. faecium E. coli P. putida S. oneidensis a b kGy 0 4 0 4 0 4 0 4 0 4 0 4 12 DNPH – +– +– +– +– +– +– +– +– +– + – + – + Coomassie

  11. Eghindi among Sahrawi refugees of Western Sahara.

    Science.gov (United States)

    Volpato, Gabriele; Waldstein, Anna

    2014-01-01

    Eghindi is an illness built around a set of pathological states experienced by Sahrawi in the desert environment of Western Sahara. Its core symptoms are caused by osmotic imbalances related to salt consumption. In 1975, many Sahrawi were exiled into refugee camps, and they have since experienced radical sociocultural changes, which are reflected in changing explanatory models of eghindi. Older and conservative refugees, attached to traditional Sahrawi culture, have expanded its conceptualization to include new pathogenic factors, while younger and progressive refugees, acculturated with Western culture, began challenging its existence. Eghindi became embodied within a broader process of negotiation of Sahrawi cultural identity. Our findings provide a framework for thinking about the evolution of illness in response to displacement, and highlight that when explanatory models evolve, intracultural tensions can arise within a population.

  12. Function and biochemical characterization of RecJ in Deinococcus radiodurans.

    Science.gov (United States)

    Jiao, Jiandong; Wang, Liangyan; Xia, Wenrong; Li, Mingfeng; Sun, Hongxing; Xu, Guangzhi; Tian, Bing; Hua, Yuejin

    2012-04-01

    The single-stranded DNA-specific nuclease RecJ is found in most bacteria where it is involved in the RecFOR double-stranded break (DSBs) repair pathway. DSBs repair mainly occurs via the RecFOR pathway in Deinococcus radiodurans, a well-known radiation-resistant bacterium. A recJ null mutant was constructed to investigate the role of recJ in D. radiodurans. recJ inactivation caused growth defects and sensitivity to high temperatures. However, the radiation resistance of the recJ mutant was only moderately decreased. The full-length D. radiodurans RecJ (DrRecJ) protein was expressed and purified to further characterize its biochemical properties. DrRecJ possessed a Mn(2+) concentration-dependent nuclease activity where the optimal Mn(2+) concentration was 0.1mM. DrRecJ had a similar activity profile after adding 10mM Mg(2+) to reactions with different Mn(2+) concentrations, indicating that Mn(2+) is a RecJ regulator. Escherichia coli RecJ has no activity on 5' ssDNA tails shorter than 6-nt, but DrRecJ could effectively degrade DNA with a 4-nt 5' ssDNA tail, suggesting that DrRecJ may have a wider range of DNA substrates. Moreover, SSB in D. radiodurans stimulated the DrRecJ exonuclease activity, whereas DdrB inhibited it and provided protection to ssDNA. Overall, our results indicate that recJ is a nonessential gene in D. radiodurans and that the activity of DrRecJ is regulated by Mn(2+) and SSB-DdrB. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Simulation of the environmental climate conditions on martian surface and its effect on Deinococcus radiodurans

    Science.gov (United States)

    de la Vega, U. Pogoda; Rettberg, P.; Reitz, G.

    The resistance of terrestrial microorganisms under the thermo-physical conditions of Mars (diurnal temperature variations, UV climate, atmospheric pressure and gas composition) at mid-latitudes was studied for the understanding and assessment of potential life processes on Mars. In order to accomplish a targeted search for life on other planets, e.g. Mars, it is necessary to know the limiting physical and chemical parameters of terrestrial life. Therefore the polyextremophile bacterium Deinococcus radiodurans was chosen as test organism for these investigations. For the simulation studies at the Planetary and Space Simulation Facilities (PSI) at DLR, Cologne, Germany, conditions that are present during the southern summer at latitude of 60° on Mars were applied. We could simulate several environmental parameters of Mars in one single experiment: vacuum/low pressure, anoxic atmosphere and diurnal cycles in temperature and relative humidity, energy-rich ultraviolet (UV) radiation as well as shielding by different martian soil analogue materials. These parameters have been applied both single and in different combinations in laboratory experiments. Astonishingly the diurnal Mars-like cycles in temperature and relative humidity affected the viability of D. radiodurans cells quite severely. But the martian UV climate turned out to be the most deleterious factor, though D. radiodurans is red-pigmented due to carotenoids incorporated in its cell wall, which have been assigned not only a possible role as free radical scavenger but also as a UV-protectant. An additional UV-protection was accomplished by mixing the bacteria with nano-sized hematite.

  14. Structural and functional studies of MutS2 from Deinococcus radiodurans.

    Science.gov (United States)

    Zhang, Hui; Xu, Qiang; Lu, Meihua; Xu, Xin; Wang, Yunguang; Wang, Liangyan; Zhao, Ye; Hua, Yuejin

    2014-09-01

    The MutS2 homologues have been found widespread in most prokaryotes, which are involved in DNA repair and reactive oxygen species detoxification. The C-terminal small mutS-related (Smr) domain is critical for its endonucleolytic activity. However, the detailed catalytic mechanism is still unclear. In this study, we first investigated the in vivo role of drMutS2 in Deinococcus radiodurans, the most radiation-resistant organism exhibits the remarkable DNA repair capacity. mutS2 and recA mutS2 double knockout mutants were constructed because the phenotype was strongly masked by the predominant homologous recombination DNA repair pathway in this bacterium. Compared with the recA mutant, cells devoid of both genes showed increased sensitivity to ionizing radiation and oxidative agents, suggesting that drMutS2 is involved in RecA-independent mechanisms that enhance cellular resistance to oxidative stress-induced DNA damage. Moreover, the basal level of reductase activity and thiamine biosynthesis was induced in the absence of mutS2. To characterize its catalytic residues, the Smr domain was crystallized and soaked in buffer containing manganese ions. In contrast to native crystals, the space group of manganese-derivative crystals transformed from monoclinic to orthorhombic unexpectedly. This type of crystals showed improved diffraction resolution to 1.2 Å, which has the highest resolution of currently known Smr structures. Structural comparison revealed that three acidic amino-acid residues, which are all located in the α1 helix, changed the rotamer states after metal soaking. Mutational analysis of conserved residue glutamic acid 710 to alanine yielded a drMutS2 variant with impaired nuclease activity, and could only partially rescue the radiosensitive phenotype of the mutS2 null strain, indicating that glutamic acid 710 is the catalytic residue. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Bioprecipitation of uranium from alkaline waste solutions using recombinant Deinococcus radiodurans.

    Science.gov (United States)

    Kulkarni, Sayali; Ballal, Anand; Apte, Shree Kumar

    2013-11-15

    Bioremediation of uranium (U) from alkaline waste solutions remains inadequately explored. We engineered the phoK gene (encoding a novel alkaline phosphatase, PhoK) from Sphingomonas sp. for overexpression in the radioresistant bacterium Deinococcus radiodurans. The recombinant strain thus obtained (Deino-PhoK) exhibited remarkably high alkaline phosphatase activity as evidenced by zymographic and enzyme activity assays. Deino-PhoK cells could efficiently precipitate uranium over a wide range of input U concentrations. At low uranyl concentrations (1 mM), the strain precipitated >90% of uranium within 2h while a high loading capacity of around 10.7 g U/g of dry weight of cells was achieved at 10 mM U concentration. Uranium bioprecipitation by Deino-PhoK cells was not affected in the presence of Cs and Sr, commonly present in intermediate and low level liquid radioactive waste, or after exposure to very high doses of ionizing radiation. Transmission electron micrographs revealed the extracellular nature of bioprecipitated U, while X-ray diffraction and fluorescence analysis identified the precipitated uranyl phosphate species as chernikovite. When immobilized into calcium alginate beads, Deino-PhoK cells efficiently removed uranium, which remained trapped in beads, thus accomplishing physical separation of precipitated uranyl phosphate from solutions. The data demonstrate superior ability of Deino-PhoK, over earlier reported strains, in removal of uranium from alkaline solutions and its potential use in bioremediation of nuclear and other waste. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Transcriptome analysis of salt-stressed Deinococcus radiodurans and characterization of salt-sensitive mutants.

    Science.gov (United States)

    Im, Seonghun; Joe, Minho; Kim, Dongho; Park, Don-Hee; Lim, Sangyong

    2013-11-01

    Deinococcus radiodurans is a bacterium best known for its extreme resistance to high levels of ionizing radiation. Gene expression profiles of D. radiodurans exposed to 0.3 M NaCl revealed that at least 389 genes were induced and 415 were repressed by twofold or more. A general down-regulation of the central metabolic pathways and a strong decrease of nrd gene expression, which encodes proteins necessary for DNA synthesis, likely reflect the growth retardation induced by NaCl stress. The expression of rsbRSTX, which encodes sigma B (σ(B)) activity regulators, was also reduced by NaCl stress even though D. radiodurans does not have σ(B). The mutation of rsbX (drB0027) decreased the tolerance of D. radiodurans to NaCl, suggesting the possible role of the Rsb module in NaCl response. On the other hand, NaCl stress activated genes associated with osmoprotectant accumulation: the pstSCAB operon, which encodes a high affinity phosphate transporter, and DRA0135 and DR1438, which are components of transporters of glycine betaine and trehalose. Survival analysis of mutant strains lacking DR0392 (membrane-binding protein) and DR1115 (S-layer protein), whose expressions were highly activated by NaCl, showed a reduction in NaCl tolerance. In addition, the Δdr0392 strain showed sensitivity to γ-irradiation compared to the wild type. These results suggest that DR0392 plays a role in the resistance of D. radiodurans to NaCl and γ-irradiation. Copyright © 2013 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  17. Cyclic AMP Receptor Protein Acts as a Transcription Regulator in Response to Stresses in Deinococcus radiodurans.

    Science.gov (United States)

    Yang, Su; Xu, Hong; Wang, Jiali; Liu, Chengzhi; Lu, Huizhi; Liu, Mengjia; Zhao, Ye; Tian, Bing; Wang, Liangyan; Hua, Yuejin

    2016-01-01

    The cyclic AMP receptor protein family of transcription factors regulates various metabolic pathways in bacteria, and also play roles in response to environmental changes. Here, we identify four homologs of the CRP family in Deinococcus radiodurans, one of which tolerates extremely high levels of oxidative stress and DNA-damaging reagents. Transcriptional levels of CRP were increased under hydrogen peroxide (H2O2) treatment during the stationary growth phase, indicating that CRPs function in response to oxidative stress. By constructing all CRP single knockout mutants, we found that the dr0997 mutant showed the lowest tolerance toward H2O2, ultraviolet radiation, ionizing radiation, and mitomycin C, while the phenotypes of the dr2362, dr0834, and dr1646 mutants showed slight or no significant differences from those of the wild-type strain. Taking advantage of the conservation of the CRP-binding site in many bacteria, we found that transcription of 18 genes, including genes encoding chromosome-partitioning protein (dr0998), Lon proteases (dr0349 and dr1974), NADH-quinone oxidoreductase (dr1506), thiosulfate sulfurtransferase (dr2531), the DNA repair protein UvsE (dr1819), PprA (dra0346), and RecN (dr1447), are directly regulated by DR0997. Quantitative real-time polymerase chain reaction (qRT-PCR) analyses showed that certain genes involved in anti-oxidative responses, DNA repair, and various cellular pathways are transcriptionally attenuated in the dr0997 mutant. Interestingly, DR0997 also regulate the transcriptional levels of all CRP genes in this bacterium. These data suggest that DR0997 contributes to the extreme stress resistance of D. radiodurans via its regulatory role in multiple cellular pathways, such as anti-oxidation and DNA repair pathways.

  18. MDP: A Deinococcus Mn2+-Decapeptide Complex Protects Mice from Ionizing Radiation.

    Science.gov (United States)

    Gupta, Paridhi; Gayen, Manoshi; Smith, Joan T; Gaidamakova, Elena K; Matrosova, Vera Y; Grichenko, Olga; Knollmann-Ritschel, Barbara; Daly, Michael J; Kiang, Juliann G; Maheshwari, Radha K

    2016-01-01

    The radioprotective capacity of a rationally-designed Mn2+-decapeptide complex (MDP), based on Mn antioxidants in the bacterium Deinococcus radiodurans, was investigated in a mouse model of radiation injury. MDP was previously reported to be extraordinarily radioprotective of proteins in the setting of vaccine development. The peptide-component (DEHGTAVMLK) of MDP applied here was selected from a group of synthetic peptides screened in vitro for their ability to protect cultured human cells and purified enzymes from extreme damage caused by ionizing radiation (IR). We show that the peptides accumulated in Jurkat T-cells and protected them from 100 Gy. MDP preserved the activity of T4 DNA ligase exposed to 60,000 Gy. In vivo, MDP was nontoxic and protected B6D2F1/J (female) mice from acute radiation syndrome. All irradiated mice treated with MDP survived exposure to 9.5 Gy (LD70/30) in comparison to the untreated mice, which displayed 63% lethality after 30 days. Our results show that MDP provides early protection of white blood cells, and attenuates IR-induced damage to bone marrow and hematopoietic stem cells via G-CSF and GM-CSF modulation. Moreover, MDP mediated the immunomodulation of several cytokine concentrations in serum including G-CSF, GM-CSF, IL-3 and IL-10 during early recovery. Our results present the necessary prelude for future efforts towards clinical application of MDP as a promising IR countermeasure. Further investigation of MDP as a pre-exposure prophylactic and post-exposure therapeutic in radiotherapy and radiation emergencies is warranted.

  19. Cyclic AMP Receptor Protein Acts as a Transcription Regulator in Response to Stresses in Deinococcus radiodurans.

    Directory of Open Access Journals (Sweden)

    Su Yang

    Full Text Available The cyclic AMP receptor protein family of transcription factors regulates various metabolic pathways in bacteria, and also play roles in response to environmental changes. Here, we identify four homologs of the CRP family in Deinococcus radiodurans, one of which tolerates extremely high levels of oxidative stress and DNA-damaging reagents. Transcriptional levels of CRP were increased under hydrogen peroxide (H2O2 treatment during the stationary growth phase, indicating that CRPs function in response to oxidative stress. By constructing all CRP single knockout mutants, we found that the dr0997 mutant showed the lowest tolerance toward H2O2, ultraviolet radiation, ionizing radiation, and mitomycin C, while the phenotypes of the dr2362, dr0834, and dr1646 mutants showed slight or no significant differences from those of the wild-type strain. Taking advantage of the conservation of the CRP-binding site in many bacteria, we found that transcription of 18 genes, including genes encoding chromosome-partitioning protein (dr0998, Lon proteases (dr0349 and dr1974, NADH-quinone oxidoreductase (dr1506, thiosulfate sulfurtransferase (dr2531, the DNA repair protein UvsE (dr1819, PprA (dra0346, and RecN (dr1447, are directly regulated by DR0997. Quantitative real-time polymerase chain reaction (qRT-PCR analyses showed that certain genes involved in anti-oxidative responses, DNA repair, and various cellular pathways are transcriptionally attenuated in the dr0997 mutant. Interestingly, DR0997 also regulate the transcriptional levels of all CRP genes in this bacterium. These data suggest that DR0997 contributes to the extreme stress resistance of D. radiodurans via its regulatory role in multiple cellular pathways, such as anti-oxidation and DNA repair pathways.

  20. Survival of Deinococcus geothermalis in Biofilms under Desiccation and Simulated Space and Martian Conditions

    Science.gov (United States)

    Frösler, Jan; Panitz, Corinna; Wingender, Jost; Flemming, Hans-Curt; Rettberg, Petra

    2017-05-01

    Biofilm formation represents a successful survival strategy for bacteria. In biofilms, cells are embedded in a matrix of extracellular polymeric substances (EPS). As they are often more stress-tolerant than single cells, biofilm cells might survive the conditions present in space and on Mars. To investigate this topic, the bacterium Deinococcus geothermalis was chosen as a model organism due to its tolerance toward desiccation and radiation. Biofilms cultivated on membranes and, for comparison, planktonically grown cells deposited on membranes were air-dried and exposed to individual stressors that included prolonged desiccation, extreme temperatures, vacuum, simulated martian atmosphere, and UV irradiation, and they were exposed to combinations of stressors that simulate space (desiccation + vacuum + UV) or martian (desiccation + Mars atmosphere + UV) conditions. The effect of sulfatic Mars regolith simulant on cell viability during stress was investigated separately. The EPS produced by the biofilm cells contained mainly polysaccharides and proteins. To detect viable but nonculturable (VBNC) cells, cultivation-independent viability indicators (membrane integrity, ATP, 16S rRNA) were determined in addition to colony counts. Desiccation for 2 months resulted in a decrease of culturability with minor changes of membrane integrity in biofilm cells and major loss of membrane integrity in planktonic bacteria. Temperatures between -25°C and +60°C, vacuum, and Mars atmosphere affected neither culturability nor membrane integrity in both phenotypes. Monochromatic (254 nm; ≥1 kJ m-2) and polychromatic (200-400 nm; >5.5 MJ m-2 for planktonic cells and >270 MJ m-2 for biofilms) UV irradiation significantly reduced the culturability of D. geothermalis but did not affect cultivation-independent viability markers, indicating the induction of a VBNC state in UV-irradiated cells. In conclusion, a substantial proportion of the D. geothermalis population remained viable under

  1. MDP: A Deinococcus Mn2+-Decapeptide Complex Protects Mice from Ionizing Radiation.

    Directory of Open Access Journals (Sweden)

    Paridhi Gupta

    Full Text Available The radioprotective capacity of a rationally-designed Mn2+-decapeptide complex (MDP, based on Mn antioxidants in the bacterium Deinococcus radiodurans, was investigated in a mouse model of radiation injury. MDP was previously reported to be extraordinarily radioprotective of proteins in the setting of vaccine development. The peptide-component (DEHGTAVMLK of MDP applied here was selected from a group of synthetic peptides screened in vitro for their ability to protect cultured human cells and purified enzymes from extreme damage caused by ionizing radiation (IR. We show that the peptides accumulated in Jurkat T-cells and protected them from 100 Gy. MDP preserved the activity of T4 DNA ligase exposed to 60,000 Gy. In vivo, MDP was nontoxic and protected B6D2F1/J (female mice from acute radiation syndrome. All irradiated mice treated with MDP survived exposure to 9.5 Gy (LD70/30 in comparison to the untreated mice, which displayed 63% lethality after 30 days. Our results show that MDP provides early protection of white blood cells, and attenuates IR-induced damage to bone marrow and hematopoietic stem cells via G-CSF and GM-CSF modulation. Moreover, MDP mediated the immunomodulation of several cytokine concentrations in serum including G-CSF, GM-CSF, IL-3 and IL-10 during early recovery. Our results present the necessary prelude for future efforts towards clinical application of MDP as a promising IR countermeasure. Further investigation of MDP as a pre-exposure prophylactic and post-exposure therapeutic in radiotherapy and radiation emergencies is warranted.

  2. Deinococcus radiodurans PriA is a Pseudohelicase.

    Directory of Open Access Journals (Sweden)

    Matthew E Lopper

    Full Text Available Reactivation of repaired DNA replication forks in bacteria is catalyzed by PriA helicase. This broadly-conserved bacterial enzyme can remodel the structure of DNA at a repaired DNA replication fork by unwinding small portions of duplex DNA to prepare the fork for replisome reloading. While PriA's helicase activity is not strictly required for cell viability in E. coli, the sequence motifs that confer helicase activity upon PriA are well-conserved among sequenced bacterial priA genes, suggesting that PriA's duplex DNA unwinding activity confers a selective advantage upon cells. However, these helicase sequence motifs are not well-conserved among priA genes from the Deinococcus-Thermus phylum. Here, we show that PriA from a highly radiation-resistant member of that phylum, Deinococcus radiodurans, lacks the ability to hydrolyze ATP and unwind duplex DNA, thus qualifying D. radiodurans PriA as a pseudohelicase. Despite the lack of helicase activity, D. radiodurans PriA has retained the DNA binding activity expected of a typical PriA helicase, and we present evidence for a physical interaction between D. radiodurans PriA and its cognate replicative helicase, DnaB. This suggests that PriA has retained a role in replisome reloading onto repaired DNA replication forks in D. radiodurans despite its lack of helicase activity.

  3. Deinococcus radiodurans PriA is a Pseudohelicase.

    Science.gov (United States)

    Lopper, Matthew E; Boone, Jacob; Morrow, Christopher

    2015-01-01

    Reactivation of repaired DNA replication forks in bacteria is catalyzed by PriA helicase. This broadly-conserved bacterial enzyme can remodel the structure of DNA at a repaired DNA replication fork by unwinding small portions of duplex DNA to prepare the fork for replisome reloading. While PriA's helicase activity is not strictly required for cell viability in E. coli, the sequence motifs that confer helicase activity upon PriA are well-conserved among sequenced bacterial priA genes, suggesting that PriA's duplex DNA unwinding activity confers a selective advantage upon cells. However, these helicase sequence motifs are not well-conserved among priA genes from the Deinococcus-Thermus phylum. Here, we show that PriA from a highly radiation-resistant member of that phylum, Deinococcus radiodurans, lacks the ability to hydrolyze ATP and unwind duplex DNA, thus qualifying D. radiodurans PriA as a pseudohelicase. Despite the lack of helicase activity, D. radiodurans PriA has retained the DNA binding activity expected of a typical PriA helicase, and we present evidence for a physical interaction between D. radiodurans PriA and its cognate replicative helicase, DnaB. This suggests that PriA has retained a role in replisome reloading onto repaired DNA replication forks in D. radiodurans despite its lack of helicase activity.

  4. Book Review: The writings of Mauritania and the western Sahara ...

    African Journals Online (AJOL)

    Abstract. Book Title: The writings of Mauritania and the western Sahara: Arabic Literature of Africa vol. 5. Book Authors: compiled by Charles C. Stewart with Sidi Ahmed Wuld Ahmed Salim. (Leiden & Boston: Brill, 2016), 2 vols ...

  5. South of Sahara | Page 25 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    South of Sahara. Sud du Sahara. Read more about Catalyzing Broadband Internet in Africa. Language English. Read more about Mobilisation du financement privé aux fins de l'adaptation. Language French. Read more about Une approche des politiques et de la gouvernance en matière d'Internet axée sur le progrès des ...

  6. South of Sahara | Page 121 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    South of Sahara. Sud du Sahara. Read more about Internet Backbone in the Democratic Republic of Congo : Feasibility Study and Advocacy. Language English. Read more about Citoyens du monde : les répercussions des programmes de travail rémunéré et de travail bénévole à l'étranger. Language French. Read more ...

  7. Growth of Deinococcus Radiodurans in Oils as Sole Source of Carbon

    Science.gov (United States)

    Dalmaso, G. Z. L.; Paulino-Lima, I. G.; Leite, S. G. F.; Leitão, A. C.; Lage, C.

    2010-04-01

    Growth of deinococcus radiodurans was analysed in (i) gasoline, diesel oil with (ii) or without (iii) additives, (iv) sergipano oil and (v) arabic light oil. High microbial abundance was confirmed for many of them.

  8. The single-stranded DNA-binding protein of Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Wood Elizabeth

    2004-01-01

    Full Text Available Abstract Background Deinococcus radiodurans R1 is one of the most radiation-resistant organisms known and is able to repair an unusually large amount of DNA damage without induced mutation. Single-stranded DNA-binding (SSB protein is an essential protein in all organisms and is involved in DNA replication, recombination and repair. The published genomic sequence from Deinococcus radiodurans includes a putative single-stranded DNA-binding protein gene (ssb; DR0100 requiring a translational frameshift for synthesis of a complete SSB protein. The apparently tripartite gene has inspired considerable speculation in the literature about potentially novel frameshifting or RNA editing mechanisms. Immediately upstream of the ssb gene is another gene (DR0099 given an ssb-like annotation, but left unexplored. Results A segment of the Deinococcus radiodurans strain R1 genome encompassing the ssb gene has been re-sequenced, and two errors involving omitted guanine nucleotides have been documented. The corrected sequence incorporates both of the open reading frames designated DR0099 and DR0100 into one contiguous ssb open reading frame (ORF. The corrected gene requires no translational frameshifts and contains two predicted oligonucleotide/oligosaccharide-binding (OB folds. The protein has been purified and its sequence is closely related to the Thermus thermophilus and Thermus aquaticus SSB proteins. Like the Thermus SSB proteins, the SSBDr functions as a homodimer. The Deinococcus radiodurans SSB homodimer stimulates Deinococcus radiodurans RecA protein and Escherichia coli RecA protein-promoted DNA three-strand exchange reactions with at least the same efficiency as the Escherichia coli SSB homotetramer. Conclusions The correct Deinococcus radiodurans ssb gene is a contiguous open reading frame that codes for the largest bacterial SSB monomer identified to date. The Deinococcus radiodurans SSB protein includes two OB folds per monomer and functions as a

  9. Exploration of Deinococcus-Thermus molecular diversity by novel group-specific PCR primers.

    Science.gov (United States)

    Theodorakopoulos, Nicolas; Bachar, Dipankar; Christen, Richard; Alain, Karine; Chapon, Virginie

    2013-10-01

    The deeply branching Deinococcus-Thermus lineage is recognized as one of the most extremophilic phylum of bacteria. In previous studies, the presence of Deinococcus-related bacteria in the hot arid Tunisian desert of Tataouine was demonstrated through combined molecular and culture-based approaches. Similarly, Thermus-related bacteria have been detected in Tunisian geothermal springs. The present work was conducted to explore the molecular diversity within the Deinococcus-Thermus phylum in these extreme environments. A set of specific primers was designed in silico on the basis of 16S rRNA gene sequences, validated for the specific detection of reference strains, and used for the polymerase chain reaction (PCR) amplification of metagenomic DNA retrieved from the Tataouine desert sand and Tunisian hot spring water samples. These analyses have revealed the presence of previously undescribed Deinococcus-Thermus bacterial sequences within these extreme environments. The primers designed in this study thus represent a powerful tool for the rapid detection of Deinococcus-Thermus in environmental samples and could also be applicable to clarify the biogeography of the Deinococcus-Thermus phylum. © 2013 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  10. Complete genome sequence of Deinococcus maricopensis type strain (LB-34T)

    Energy Technology Data Exchange (ETDEWEB)

    Pukall, Rudiger [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Zeytun, Ahmet [Los Alamos National Laboratory (LANL); Lucas, Susan [Joint Genome Institute, Walnut Creek, California; Lapidus, Alla L. [Joint Genome Institute, Walnut Creek, California; Hammon, Nancy [Joint Genome Institute, Walnut Creek, California; Deshpande, Shweta [Joint Genome Institute, Walnut Creek, California; Nolan, Matt [Joint Genome Institute, Walnut Creek, California; Cheng, Jan-Fang [Joint Genome Institute, Walnut Creek, California; Pitluck, Sam [Joint Genome Institute, Walnut Creek, California; Liolios, Konstantinos [Joint Genome Institute, Walnut Creek, California; Pagani, Ioanna [Joint Genome Institute, Walnut Creek, California; Mikhailova, Natalia [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Pati, Amrita [U.S. Department of Energy, Joint Genome Institute; Tapia, Roxanne [Los Alamos National Laboratory (LANL); Han, Cliff [Los Alamos National Laboratory (LANL); Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Chen, Amy [Joint Genome Institute, Walnut Creek, California; Palaniappan, Krishna [Joint Genome Institute, Walnut Creek, California; Land, Miriam L [ORNL; Hauser, Loren John [ORNL; Chang, Yun-Juan [ORNL; Jeffries, Cynthia [Oak Ridge National Laboratory (ORNL); Brambilla, Evelyne-Marie [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Rohde, Manfred [HZI - Helmholtz Centre for Infection Research, Braunschweig, Germany; Goker, Markus [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Detter, J. Chris [Joint Genome Institute, Walnut Creek, California; Woyke, Tanja [Joint Genome Institute, Walnut Creek, California; Bristow, James [Joint Genome Institute, Walnut Creek, California; Eisen, Jonathan [Joint Genome Institute, Walnut Creek, California; Markowitz, Victor [Joint Genome Institute, Walnut Creek, California; Hugenholtz, Philip [U.S. Department of Energy, Joint Genome Institute; Kyrpides, Nikos C [Joint Genome Institute, Walnut Creek, California; Klenk, Hans-Peter [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany

    2011-01-01

    Deinococcus maricopensis (Rainey and da Costa 2005) is a member of the genus Deinococcus, which is comprised of 44 validly named species and is located within the deeply branching bacterial phylum Deinococcus Thermus. Strain LB-34T was isolated from a soil sample from the Sonoran Desert in Arizona. Various species of the genus Deinococcus are characterized by extreme radiation resistance, with D. maricopensis being resistant in excess of 10 kGy. Even though the genomes of three Deinococcus species, D. radiodurans, D. geothermalis and D. deserti, have already been published, no special physiological characteristic is currently known that is unique to this group. It is therefore of special interest to analyze the genomes of additional species of the genus Deinococcus to better understand how these species adapted to gamma- or UV ionizing-radiation. The 3,498,530 bp long genome of D. maricopensis with its 3,301 protein-coding and 66 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  11. Paleohydrology and paleoenvironments at Bir Sahara: Pleistocene lithostratigraphy and sedimentology in the southern Egyptian Sahara

    Science.gov (United States)

    Hill, Christopher L.; Schild, Romuald

    2017-12-01

    The Bir Sahara area contains a remarkable record of Middle and Late Pleistocene hydrologic and environmental conditions for Saharan North Africa, based on lithostratigraphic and sedimentologic evidence from basin-fill deposits. Some of the deposits contain Lower Paleolithic (Acheulean) or Middle Paleolithic artifacts that help to constrain their age, since Acheulian artifacts are assigned to the Middle Pleistocene, while Middle Paleolithic artifacts are limited to either the Middle or Late Pleistocene. Locality BS-14 is in the southern part of Bir Sahara, while localities E-88-15, E-88-2, BS-13, and BS-16 are situated in the south-central part of the deflational basin, closer to the present-day water-hole. Lowered groundwater conditions during arid intervals resulted in erosional topographic basins. These deflational basins were later filled with sediments associated with wetter hydrologic conditions. The oldest studied sedimentary sequence in the Bir Sahara depression (BS-14) contains in situ Acheulian artifacts. Acheulian handaxes are found in sands underlying carbonates that are interpreted as evidence of spring-fed pond and marsh environments during a Middle Pleistocene wet interval. At the E-88-15 locality, the stratigraphic sequence documents deposition in a possible perennial pond or small lake that varied in extent and depth and is associated with Middle Paleolithic artifacts. At E-88-12 and BS-13, lateral and vertical variations in the lithofacies of the basin-fill sediments provide additional records of changing hydrologic conditions during the Late Pleistocene. These hydrologic conditions appear to reflect variations in water-table levels related to groundwater recharge and, at times, local rains.

  12. Deciphering peculiar protein-protein interacting modules in Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Barkallah Insaf

    2009-04-01

    Full Text Available Abstract Interactomes of proteins under positive selection from ionizing-radiation-resistant bacteria (IRRB might be a part of the answer to the question as to how IRRB, particularly Deinococcus radiodurans R1 (Deira, resist ionizing radiation. Here, using the Database of Interacting Proteins (DIP and the Protein Structural Interactome (PSI-base server for PSI map, we have predicted novel interactions of orthologs of the 58 proteins under positive selection in Deira and other IRRB, but which are absent in IRSB. Among these, 18 domains and their interactomes have been identified in DNA checkpoint and repair; kinases pathways; energy and nucleotide metabolisms were the important biological processes that were found to be involved. This finding provides new clues to the cellular pathways that can to be important for ionizing-radiation resistance in Deira.

  13. Regulation of transcription initiation by Gfh factors from Deinococcus radiodurans.

    Science.gov (United States)

    Agapov, Aleksei; Esyunina, Daria; Pupov, Danil; Kulbachinskiy, Andrey

    2016-12-01

    Transcription factors of the Gre family bind within the secondary channel of bacterial RNA polymerase (RNAP) directly modulating its catalytic activities. Universally conserved Gre factors activate RNA cleavage by RNAP, by chelating catalytic metal ions in the RNAP active site, and facilitate both promoter escape and transcription elongation. Gfh factors are Deinococcus/Thermus-specific homologues of Gre factors whose transcription functions remain poorly understood. Recently, we found that Gfh1 and Gfh2 proteins from Deinococcus radiodurans dramatically stimulate RNAP pausing during transcription elongation in the presence of Mn(2+), but not Mg(2+), ions. In contrast, we show that Gfh1 and Gfh2 moderately inhibit transcription initiation in the presence of either Mg(2+) or Mn(2+) ions. By using a molecular beacon assay, we demonstrate that Gfh1 and Gfh2 do not significantly change promoter complex stability or the rate of promoter escape by D. radiodurans RNAP. At the same time, Gfh factors significantly increase the apparent KM value for the 5'-initiating nucleotide, without having major effects on the affinity of metal ions for the RNAP active site. Similar inhibitory effects of Gfh factors are observed for transcription initiation on promoters recognized by the principal and an alternative σ factor. In summary, our data suggest that D. radiodurans Gfh factors impair the binding of initiating substrates independently of the metal ions bound in the RNAP active site, but have only mild overall effects on transcription initiation. Thus the mechanisms of modulation of RNAP activity by these factors are different for various steps of transcription. © 2016 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  14. Pyrroloquinoline quinone and a quinoprotein kinase support γ-radiation resistance in Deinococcus radiodurans and regulate gene expression.

    Science.gov (United States)

    Rajpurohit, Yogendra Singh; Desai, Shruti Sumeet; Misra, Hari Sharan

    2013-06-01

    Deinococcus radiodurans is known for its extraordinary resistance to various DNA damaging agents including γ-radiation and desiccation. The pqqE:cat and Δdr2518 mutants making these cells devoid of pyrroloquinoline quinone (PQQ) and a PQQ inducible Ser/Thr protein kinase, respectively, became sensitive to γ-radiation. Transcriptome analysis of these mutants showed differential expression of the genes including those play roles in oxidative stress tolerance and (DSB) repair in D. radiodurans and in genome maintenance and stress response in other bacteria. Escherichia coli cells expressing DR2518 and PQQ showed improved resistance to γ-radiation, which increased further when both DR2518 and PQQ were present together. Although, profiles of genes getting affected in these mutants were different, there were still a few common genes showing similar expression trends in both the mutants and some others as reported earlier in oxyR and pprI mutant of this bacterium. These results suggested that PQQ and DR2518 have independent roles in γ-radiation resistance of D. radiodurans but their co-existence improves radioresistance further, possibly by regulating differential expression of the genes important for bacterial response to oxidative stress and DNA damage. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Deletion of the rnl gene encoding a nick-sealing RNA ligase sensitizes Deinococcus radiodurans to ionizing radiation.

    Science.gov (United States)

    Schmier, Brad J; Chen, Xinguo; Wolin, Sandra; Shuman, Stewart

    2017-04-20

    Deinococcus radiodurans RNA ligase (DraRnl) seals 3΄-OH/5΄-PO4 nicks in duplex nucleic acids in which the 3΄-OH nick terminus consists of two or more ribonucleotides. DraRnl exemplifies a widely distributed Rnl5 family of nick-sealing RNA ligases, the physiological functions of which are uncharted. Here we show via gene knockout that whereas DraRnl is inessential for growth of D. radiodurans, its absence sensitizes the bacterium to killing by ionizing radiation (IR). DraRnl protein is present in exponentially growing and stationary phase cells, but is depleted during the early stages of recovery from 10 kGy of IR and subsequently replenished during the late phase of post-IR genome reassembly. Absence of DraRnl elicts a delay in reconstitution of the 10 kGy IR-shattered D. radiodurans replicons that correlates with the timing of DraRnl replenishment in wild-type cells. Complementation with a catalytically dead mutant highlights that nick sealing activity is important for the radioprotective function of DraRnl. Our findings suggest a scenario in which DraRnl acts at genomic nicks resulting from gap-filling by a ribonucleotide-incorporating repair polymerase. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  16. Surface (S)-layer proteins of Deinococcus radiodurans and their utility as vehicles for surface localization of functional proteins.

    Science.gov (United States)

    Misra, Chitra Seetharam; Basu, Bhakti; Apte, Shree Kumar

    2015-12-01

    The radiation resistant bacterium, Deinococcus radiodurans contains two major surface (S)-layer proteins, Hpi and SlpA. The Hpi protein was shown to (a) undergo specific in vivo cleavage, and (b) closely associate with the SlpA protein. Using a non-specific acid phosphatase from Salmonella enterica serovar Typhi, PhoN as a reporter, the Surface Layer Homology (SLH) domain of SlpA was shown to bind deinococcal peptidoglycan-containing cell wall sacculi. The association of SlpA with Hpi on one side and peptidoglycan on the other, localizes this protein in the 'interstitial' layer of the deinoccocal cell wall. Gene chimeras of hpi-phoN and slh-phoN were constructed to test efficacy of S-layer proteins, as vehicles for cell surface localization in D. radiodurans. The Hpi-PhoN protein localized exclusively in the membrane fraction, and displayed cell-based phosphatase activity in vivo. The SLH-PhoN, which localized to both cytosolic and membrane fractions, displayed in vitro activity but no cell-based in vivo activity. Hpi, therefore, emerged as an efficient surface localizing protein and can be exploited for suitable applications of this superbug. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Proteometabolomic response of Deinococcus radiodurans exposed to UVC and vacuum conditions: Initial studies prior to the Tanpopo space mission.

    Science.gov (United States)

    Ott, Emanuel; Kawaguchi, Yuko; Kölbl, Denise; Chaturvedi, Palak; Nakagawa, Kazumichi; Yamagishi, Akihiko; Weckwerth, Wolfram; Milojevic, Tetyana

    2017-01-01

    The multiple extremes resistant bacterium Deinococcus radiodurans is able to withstand harsh conditions of simulated outer space environment. The Tanpopo orbital mission performs a long-term space exposure of D. radiodurans aiming to investigate the possibility of interplanetary transfer of life. The revealing of molecular machinery responsible for survivability of D. radiodurans in the outer space environment can improve our understanding of underlying stress response mechanisms. In this paper, we have evaluated the molecular response of D. radiodurans after the exposure to space-related conditions of UVC irradiation and vacuum. Notably, scanning electron microscopy investigations showed that neither morphology nor cellular integrity of irradiated cells was affected, while integrated proteomic and metabolomic analysis revealed numerous molecular alterations in metabolic and stress response pathways. Several molecular key mechanisms of D. radiodurans, including the tricarboxylic acid cycle, the DNA damage response systems, ROS scavenging systems and transcriptional regulators responded in order to cope with the stressful situation caused by UVC irradiation under vacuum conditions. These results reveal the effectiveness of the integrative proteometabolomic approach as a tool in molecular analysis of microbial stress response caused by space-related factors.

  18. Expression of PprI from Deinococcus radiodurans Improves Lactic Acid Production and Stress Tolerance in Lactococcus lactis.

    Directory of Open Access Journals (Sweden)

    Xiangrong Dong

    Full Text Available PprI is a general switch protein that regulates the expression of certain proteins involved in pathways of cellular resistance in the extremophilic bacterium Deinococcus radiodurans. In this study, we transformed pprI into Lactococcus lactis strain MG1363 using the lactococcal shuttle vector pMG36e and investigated its effects on the tolerance and lactic acid production of L. lactis while under stress. PprI was stably expressed in L. lactis as confirmed by western blot assays. L. lactis expressing PprI exhibited significantly improved resistance to oxidative stress and high osmotic pressure. This enhanced cellular tolerance to stressors might be due to the regulation of resistance-related genes (e.g., recA, recO, sodA, and nah by pprI. Moreover, transformed L. lactis demonstrated increased lactic acid production, attributed to enhanced lactate dehydrogenase activity. These results suggest that pprI can improve the tolerance of L. lactis to environmental stresses, and this transformed bacterial strain is a promising candidate for industrial applications of lactic acid production.

  19. Proteometabolomic response of Deinococcus radiodurans exposed to UVC and vacuum conditions: Initial studies prior to the Tanpopo space mission.

    Directory of Open Access Journals (Sweden)

    Emanuel Ott

    Full Text Available The multiple extremes resistant bacterium Deinococcus radiodurans is able to withstand harsh conditions of simulated outer space environment. The Tanpopo orbital mission performs a long-term space exposure of D. radiodurans aiming to investigate the possibility of interplanetary transfer of life. The revealing of molecular machinery responsible for survivability of D. radiodurans in the outer space environment can improve our understanding of underlying stress response mechanisms. In this paper, we have evaluated the molecular response of D. radiodurans after the exposure to space-related conditions of UVC irradiation and vacuum. Notably, scanning electron microscopy investigations showed that neither morphology nor cellular integrity of irradiated cells was affected, while integrated proteomic and metabolomic analysis revealed numerous molecular alterations in metabolic and stress response pathways. Several molecular key mechanisms of D. radiodurans, including the tricarboxylic acid cycle, the DNA damage response systems, ROS scavenging systems and transcriptional regulators responded in order to cope with the stressful situation caused by UVC irradiation under vacuum conditions. These results reveal the effectiveness of the integrative proteometabolomic approach as a tool in molecular analysis of microbial stress response caused by space-related factors.

  20. G-quadruplex forming structural motifs in the genome of Deinococcus radiodurans and their regulatory roles in promoter functions.

    Science.gov (United States)

    Kota, Swathi; Dhamodharan, V; Pradeepkumar, P I; Misra, Hari S

    2015-11-01

    Deinococcus radiodurans displays compromised radioresistance in the presence of guanine quadruplex (G4)-binding drugs (G4 drugs). Genome-wide scanning showed islands of guanine runs (G-motif) in the upstream regions of coding sequences as well as in the structural regions of many genes, indicating a role for G4 DNA in the regulation of genome functions in this bacterium. G-motifs present upstream to some of the DNA damage-responsive genes like lexA, pprI, recF, recQ, mutL and radA were synthesized, and the formation of G4 DNA structures was probed in vitro. The G-motifs present at the 67th position upstream to recQ and at the 121st position upstream to mutL produced parallel and mixed G4 DNA structures, respectively. Expression of β-galactosidase under recQ and mutL promoters containing respective G-motifs was inhibited by G4 drugs under normal growth conditions in D. radiodurans. However, when such cells were exposed to γ radiation, mutL promoter activity was stimulated while recQ promoter activity was inhibited in the presence of G4 drugs. Deletion of the G-motif from the recQ promoter could relax it from G4 drug repression. D. radiodurans cells treated with G4 drug showed reduction in recQ expression and γ radiation resistance, indicating an involvement of G4 DNA in the radioresistance of this bacterium. These results suggest that G-motifs from D. radiodurans genome form different types of G4 DNA structures at least in vitro, and the recQ and mutL promoters seem to be differentially regulated at the levels of G4 DNA structures.

  1. Spain and the Western Sahara: the Political Party Dimension

    Directory of Open Access Journals (Sweden)

    Jordi Vaquer i Fanés

    2007-12-01

    Full Text Available Since the Spanish army’s hasty withdrawal from Western Sahara in 1975, the two main parties since Spain acquired its democracy have differed over what stance should be taken with respect to the Sahara issue. The aim of this article is to establish to what extentthis is the result of the opposing government/opposition dynamic and how far it is a result of the parties’ own stances, by analysing the evolution of their attitudes and approaches with respect to the Sahara issue. The hypothesis is that the Spanish parties’ position with respect to Algeria and Morocco was initially very much determined by their view of the Sahara issue, but that there has been an inversion of this attitude. Thus at present, opposing stances on the Sahara issue are mainly the result of different views on Spain’s interests in the Maghreb region and, above all, of different ideas about which country Morocco or Algeria should benefit most from bilateral relations.

  2. The unique branching patterns of Deinococcus glycogen branching enzymes are determined by their N-terminal domains.

    NARCIS (Netherlands)

    Palomo, M.; Kralj, S.; van der Maarel, M. J. E. C.; Dijkhuizen, L.

    2009-01-01

    Glycogen branching enzymes (GBE) or 1,4-alpha-glucan branching enzymes (EC 2.4.1.18) introduce alpha-1,6 branching points in alpha-glucans, e.g., glycogen. To identify structural features in GBEs that determine their branching pattern specificity, the Deinococcus geothermalis and Deinococcus

  3. Frontières et nationalisme autour du Sahara Occidental (Borders and Nationalism in Western Sahara)

    OpenAIRE

    Luis Martinez

    2011-01-01

    Le conflit du Sahara Occidental apparaît comme le principal facteur de blocage dans la construction d'une intégration régionale. Pour la monarchie marocaine, il lui a permis de s'approprier le sentiment nationaliste alors porté par le mouvement de l'Istiqlal qui faisait de la cause du grand Maroc l'un de ses combats politiques. Pour le régime algérien, il a représenté un moyen de justifier le pouvoir d'une armée et d'entretenir le sentiment nationaliste. L'avantage du conflit saharien était é...

  4. Structure determination of uracil-DNA N-glycosylase from Deinococcus radiodurans in complex with DNA.

    Science.gov (United States)

    Pedersen, Hege Lynum; Johnson, Kenneth A; McVey, Colin E; Leiros, Ingar; Moe, Elin

    2015-10-01

    Uracil-DNA N-glycosylase (UNG) is a DNA-repair enzyme in the base-excision repair (BER) pathway which removes uracil from DNA. Here, the crystal structure of UNG from the extremophilic bacterium Deinococcus radiodurans (DrUNG) in complex with DNA is reported at a resolution of 1.35 Å. Prior to the crystallization experiments, the affinity between DrUNG and different DNA oligonucleotides was tested by electrophoretic mobility shift assays (EMSAs). As a result of this analysis, two 16 nt double-stranded DNAs were chosen for the co-crystallization experiments, one of which (16 nt AU) resulted in well diffracting crystals. The DNA in the co-crystal structure contained an abasic site (substrate product) flipped into the active site of the enzyme, with no uracil in the active-site pocket. Despite the high resolution, it was not possible to fit all of the terminal nucleotides of the DNA complex into electron density owing to disorder caused by a lack of stabilizing interactions. However, the DNA which was in contact with the enzyme, close to the active site, was well ordered and allowed detailed analysis of the enzyme-DNA interaction. The complex revealed that the interaction between DrUNG and DNA is similar to that in the previously determined crystal structure of human UNG (hUNG) in complex with DNA [Slupphaug et al. (1996). Nature (London), 384, 87-92]. Substitutions in a (here defined) variable part of the leucine loop result in a shorter loop (eight residues instead of nine) in DrUNG compared with hUNG; regardless of this, it seems to fulfil its role and generate a stabilizing force with the minor groove upon flipping out of the damaged base into the active site. The structure also provides a rationale for the previously observed high catalytic efficiency of DrUNG caused by high substrate affinity by demonstrating an increased number of long-range electrostatic interactions between the enzyme and the DNA. Interestingly, specific interactions between residues

  5. Deinococcus Mn(2+)-peptide complex: A novel approach to alphavirus vaccine development.

    Science.gov (United States)

    Gayen, Manoshi; Gupta, Paridhi; Morazzani, Elaine M; Gaidamakova, Elena K; Knollmann-Ritschel, Barbara; Daly, Michael J; Glass, Pamela J; Maheshwari, Radha K

    2017-06-22

    Over the last ten years, Chikungunya virus (CHIKV), an Old World alphavirus has caused numerous outbreaks in Asian and European countries and the Americas, making it an emerging pathogen of great global health importance. Venezuelan equine encephalitis virus (VEEV), a New World alphavirus, on the other hand, has been developed as a bioweapon in the past due to its ease of preparation, aerosol dispersion and high lethality in aerosolized form. Currently, there are no FDA approved vaccines against these viruses. In this study, we used a novel approach to develop inactivated vaccines for VEEV and CHIKV by applying gamma-radiation together with a synthetic Mn-decapeptide-phosphate complex (MnDpPi), based on manganous-peptide-orthophosphate antioxidants accumulated in the extremely radiation-resistant bacterium Deinococcus radiodurans. Classical gamma-irradiated vaccine development approaches are limited by immunogenicity-loss due to oxidative damage to the surface proteins at the high doses of radiation required for complete virus-inactivation. However, addition of MnDpPi during irradiation process selectively protects proteins, but not the nucleic acids, from the radiation-induced oxidative damage, as required for safe and efficacious vaccine development. Previously, this approach was used to develop a bacterial vaccine. In the present study, we show that this approach can successfully be applied to protecting mice against viral infections. Irradiation of VEEV and CHIKV in the presence of MnDpPi resulted in substantial epitope preservation even at supra-lethal doses of gamma-rays (50,000Gy). Irradiated viruses were found to be completely inactivated and safe in vivo (neonatal mice). Upon immunization, VEEV inactivated in the presence of MnDpPi resulted in drastically improved protective efficacy. Thus, the MnDpPi-based gamma-inactivation approach described here can readily be applied to developing vaccines against any pathogen of interest in a fast and cost

  6. Characterization of a Nudix hydrolase from Deinococcus radiodurans with a marked specificity for (deoxyribonucleoside 5'-diphosphates

    Directory of Open Access Journals (Sweden)

    Kamiya Hiroyuki

    2004-05-01

    Full Text Available Abstract Background Nudix hydrolases form a protein family whose function is to hydrolyse intracellular nucleotides and so regulate their levels and eliminate potentially toxic derivatives. The genome of the radioresistant bacterium Deinococcus radiodurans encodes 25 nudix hydrolases, an unexpectedly large number. These may contribute to radioresistance by removing mutagenic oxidised and otherwise damaged nucleotides. Characterisation of these hydrolases is necessary to understand the reason for their presence. Here, we report the cloning and characterisation of the DR0975 gene product, a nudix hydrolase that appears to be unique to this organism. Results The DR0975 gene was cloned and expressed as a 20 kDa histidine-tagged recombinant product in Escherichia coli. Substrate analysis of the purified enzyme showed it to act primarily as a phosphatase with a marked preference for (deoxynucleoside 5'-diphosphates (dGDP > ADP > dADP > GDP > dTDP > UDP > dCDP > CDP. Km for dGDP was 110 μM and kcat was 0.18 s-1 under optimal assay conditions (pH 9.4, 7.5 mM Mg2+. 8-Hydroxy-2'-deoxyguanosine 5'-diphosphate (8-OH-dGDP was also a substrate with a Km of 170 μM and kcat of 0.13 s-1. Thus, DR0975 showed no preference for 8-OH-dGDP over dGDP. Limited pyrophosphatase activity was also observed with NADH and some (diadenosine polyphosphates but no other substrates. Expression of the DR0975 gene was undetectable in logarithmic phase cells but was induced at least 30-fold in stationary phase. Superoxide, but not peroxide, stress and slow, but not rapid, dehydration both caused a slight induction of the DR0975 gene. Conclusion Nucleotide substrates for nudix hydrolases conform to the structure NDP-X, where X can be one of several moieties. Thus, a preference for (dNDPs themselves is most unusual. The lack of preference for 8-OH-dGDP over dGDP as a substrate combined with the induction in stationary phase, but not by peroxide or superoxide, suggests that the

  7. Subterranean Microhabitat Dependent Intra Versus Extracellular Enzyme Secretion Capabilities of Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Jayant Biswas

    2015-04-01

    Full Text Available Deinococcus radiodurans is one of the most yet discovered extremophilic microbe, the isolation of which from the various habitats of Kotumsar cave is always a matter of enticement to discover its ecological economics. In the present work we studied the intra versus extracellular alkaline protease and glucose isomerase secretion capabilities of Deinococcus radiodurans; KCB21, KCB50, KCB93 isolated from three distinct subterranean niches of Kotumsar cave. The selected niches/zones were the entrance zone, transient zone and the deep inner zone from where the soil sediments were collected to isolate the bacterial strains. The results revealed high extracellular alkaline protease activity from the Deinococcus radiodurans strain which was isolated from the deeper zones of the cave, whereas no such phenomenon was revealed for glucose isomerase. The possible reason for the obtained results has been discussed.

  8. South of Sahara | Page 9 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    flexible layoutflexible layoutflexible layoutflexible layoutflexible layoutflexible layoutflexible layoutflexible layoutflexible layoutflexible layout. Sud du Sahara. Pages. « first · ‹ previous … 2 · 3 · 4 · 5 · 6 · 7 · 8; 9; 10 · next › · last » · What we do · Funding · Resources · About IDRC. Knowledge. Innovation. Solutions.

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    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Read more about Exemption communautaire du paiement des services de santé au Burkina Faso. Language French. Read more about Études par pays dans le cadre du HIV/AIDS Monitor. Language French. Read more about HIV/AIDS Monitor Country Studies. Language English. Read more about Gestion ...

  10. Modeling non-monotone risk aversion using SAHARA utility functions

    NARCIS (Netherlands)

    Chen, A.; Pelsser, A.; Vellekoop, M.

    2011-01-01

    We develop a new class of utility functions, SAHARA utility, with the distinguishing feature that it allows absolute risk aversion to be non-monotone and implements the assumption that agents may become less risk averse for very low values of wealth. The class contains the well-known exponential and

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    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Read more about National Innovation Systems in Brazil, Russia, India, China and South Africa (BRICS). Language English. Read more about Strengthening the Capacity to Adapt to Climate Change in Rural Bénin. Language English. Read more about Renforcement des capacités d'adaptation des acteurs ...

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    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Read more about Hybrid Security Arrangements in Africa: Exploring the Implications for State-building. Language English. Read more about Chiffrer le travail des femmes - économie sexiste sur le marché et au foyer. Language French. Read more about Implications des mécanismes de sécurité hybrides ...

  13. South of Sahara | Page 31 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Read more about Action multisectorielle en matière de prévention des maladies non transmissibles en Afrique subsaharienne. Language French. Read more about Safe and Inclusive Cities: Research to Reduce Urban Violence, Poverty, and Inequalities. Language English. Read more about Analyse des ...

  14. The Sources Of Protracted Conflict In The Western Sahara

    Science.gov (United States)

    2016-03-01

    increasing unrest, the French and Spanish divided the Sherifian Empire into three territories in (1912). France promoted colonization to secure its...opinions on two questions: 1. Was Western Sahara a territory belonging to no one (terra nullius) at the time of Spanish colonization ? 2. What were the...1. History Leading up to the Occupation .......................................16 2. Spanish Decolonization (1956–1976

  15. Biological decolorization of malachite green by Deinococcus radiodurans R1.

    Science.gov (United States)

    Lv, Guo-Ying; Cheng, Jian-Hui; Chen, Xiao-Yang; Zhang, Zuo-Fa; Fan, Lei-Fa

    2013-09-01

    Cultures of Deinococcus radiodurans R1 were observed to decolorize malachite green (MG) dye. The effects of various factors on decolorization efficiency were investigated. The optimal decolorization temperature and pH ranges were 25-50°C and 6.0-8.0, respectively. With increasing initial MG concentration, the decolorization efficiency decreased, and the kinetic parameters, R(MG,max) and K(m) were 416.7 mg-MG/g-cell/h and 1033.7 mg/L, respectively. The D. radiodurans R1 cells were capable of tolerating and rapidly degrading high concentrations of the dye. When MG concentration was 200 mg/L, decolorization efficiency was up to 97.2% within 30 min. The intermediate products of MG biodegradation were 4-(dimethylamino)phenol and 4-(dimethylamino)benzophenone, as identified by gas chromatography/mass spectrometry analysis. Toxicity tests indicated that D. radiodurans R1 did not detoxify an MG solution completely, but clearly reduced its toxicity. This study demonstrated that this strain was an efficient degrader compared to other microorganisms. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Contact-free cold atmospheric plasma treatment of Deinococcus radiodurans.

    Science.gov (United States)

    Maisch, Tim; Shimizu, Tetsuji; Mitra, Anindita; Heinlin, Julia; Karrer, Sigrid; Li, Yang-Fang; Morfill, Gregor; Zimmermann, Julia L

    2012-09-01

    In this study we investigated the sensitivity of Deinococcus radiodurans to contact-free cold atmospheric plasma treatment as part of a project to establish new efficient procedures for disinfection of inanimate surfaces. The Gram-positive D. radiodurans is one of the most resistant microorganisms worldwide. Stationary phases of D. radiodurans were exposed to cold atmospheric plasma for different time intervals or to ultraviolet C (UVC) radiation at dose rates of 0.001-0.0656 J cm⁻², respectively. A methicillin-resistant Staphylococcus aureus strain (MRSA) served as control for Gram-positive bacteria. The surface microdischarge plasma technology was used for generation of cold atmospheric plasma. A plasma discharge was ignited using ambient air. Surprisingly, D. radiodurans was sensitive to the cold atmospheric plasma treatment in the same range as the MRSA strain. Survival of both bacteria decreased with increasing plasma exposure times up to 6 log₁₀ cycles (>99.999 %) within 20 s of plasma treatment. In contrast, UVC radiation of both bacteria demonstrated that D. radiodurans was more resistant to UVC treatment than MRSA. Cold atmospheric plasma seems to be a promising tool for industrial and clinical purposes where time-saving is a critical point to achieve efficient disinfection of inanimate surfaces and where protection from corrosive materials is needed.

  17. DNA adenine hypomethylation leads to metabolic rewiring in Deinococcus radiodurans.

    Science.gov (United States)

    Shaiwale, Nayana S; Basu, Bhakti; Deobagkar, Deepti D; Deobagkar, Dileep N; Apte, Shree K

    2015-08-03

    The protein encoded by DR_0643 gene from Deinococcus radiodurans was shown to be an active N-6 adenine-specific DNA methyltransferase (Dam). Deletion of corresponding protein reduced adenine methylation in the genome by 60% and resulted in slow-growth phenotype. Proteomic changes induced by DNA adenine hypomethylation were mapped by two-dimensional protein electrophoresis coupled with mass spectrometry. As compared to wild type D. radiodurans cells, at least 54 proteins were differentially expressed in Δdam mutant. Among these, 39 metabolic enzymes were differentially expressed in Δdam mutant. The most prominent change was DNA adenine hypomethylation induced de-repression of pyruvate dehydrogenase complex, E1 component (aceE) gene resulting in 10 fold increase in the abundance of corresponding protein. The observed differential expression profile of metabolic enzymes included increased abundance of enzymes involved in fatty acid and amino acid degradation to replenish acetyl Co-A and TCA cycle intermediates and diversion of phosphoenolpyruvate and pyruvate into amino acid biosynthesis, a metabolic rewiring attempt by Δdam mutant to restore energy generation via glycolysis-TCA cycle axis. This is the first report of DNA adenine hypomethylation mediated rewiring of metabolic pathways in prokaryotes. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Small-molecule antioxidant proteome-shields in Deinococcus radiodurans.

    Directory of Open Access Journals (Sweden)

    Michael J Daly

    2010-09-01

    Full Text Available For Deinococcus radiodurans and other bacteria which are extremely resistant to ionizing radiation, ultraviolet radiation, and desiccation, a mechanistic link exists between resistance, manganese accumulation, and protein protection. We show that ultrafiltered, protein-free preparations of D. radiodurans cell extracts prevent protein oxidation at massive doses of ionizing radiation. In contrast, ultrafiltrates from ionizing radiation-sensitive bacteria were not protective. The D. radiodurans ultrafiltrate was enriched in Mn, phosphate, nucleosides and bases, and peptides. When reconstituted in vitro at concentrations approximating those in the D. radiodurans cytosol, peptides interacted synergistically with Mn(2+ and orthophosphate, and preserved the activity of large, multimeric enzymes exposed to 50,000 Gy, conditions which obliterated DNA. When applied ex vivo, the D. radiodurans ultrafiltrate protected Escherichia coli cells and human Jurkat T cells from extreme cellular insults caused by ionizing radiation. By establishing that Mn(2+-metabolite complexes of D. radiodurans specifically protect proteins against indirect damage caused by gamma-rays delivered in vast doses, our findings provide the basis for a new approach to radioprotection and insight into how surplus Mn budgets in cells combat reactive oxygen species.

  19. Description of four novel psychrophilic, ionizing radiation-sensitive Deinococcus species from alpine environments.

    Science.gov (United States)

    Callegan, Ryan P; Nobre, M Fernanda; McTernan, Patrick M; Battista, John R; Navarro-González, Rafael; McKay, Christopher P; da Costa, Milton S; Rainey, Fred A

    2008-05-01

    Five psychrophilic bacterial strains were isolated from soil samples collected above the treeline of alpine environments. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these organisms represent four novel species of the genus Deinococcus; levels of sequence similarity to the type strains of recognized Deinococcus species were in the range 89.3-94.7 %. Strains PO-04-20-132T, PO-04-20-144, PO-04-19-125T, ME-04-01-32T and ME-04-04-52T grew aerobically, with optimum growth at 10 degrees C and at pH 6-9. The major respiratory menaquinone was MK-8. The fatty acid profiles of strains PO-04-20-132T, PO-04-20-144, PO-04-19-125T and ME-04-01-32T were dominated by 16 : 1omega7c, 17 : 0 iso and 15 : 1omega6c, whereas 16 : 1omega7c, 17 : 0 cyclo and 16 : 0 predominated in strain ME-04-04-52T. The DNA G+C contents of strains PO-04-20-132T, PO-04-19-125T, ME-04-01-32T and ME-04-04-52T were 63.2, 63.1, 65.9 and 62.6 mol%, respectively. Strains PO-04-20-132T, PO-04-19-125T, ME-04-01-32T and ME-04-04-52T had gamma radiation D10 (dose required to reduce the bacterial population by 10-fold) values of < or =4 kGy. These four strains showed sensitivity to UV radiation and extended desiccation as compared with Deinococcus radiodurans. On the basis of the phylogenetic analyses, and chemotaxonomic and phenotypic data, it is proposed that strains PO-04-20-132T (=LMG 24019T=NRRL B-41950T; Deinococcus radiomollis sp. nov.), PO-04-19-125T (=LMG 24282T=NRRL B-41949T; Deinococcus claudionis sp. nov.), ME-04-01-32T (=LMG 24022T=NRRL B-41947T; Deinococcus altitudinis sp. nov.) and ME-04-04-52T (=LMG 24283T=NRRL B-41948T; Deinococcus alpinitundrae sp. nov.) represent the type strains of four novel species of the genus Deinococcus.

  20. Atmospheric feedbacks in North Africa from an irrigated, afforested Sahara

    Science.gov (United States)

    Kemena, Tronje Peer; Matthes, Katja; Martin, Thomas; Wahl, Sebastian; Oschlies, Andreas

    2017-09-01

    Afforestation of the Sahara has been proposed as a climate engineering method to sequester a substantial amount of carbon dioxide, potentially effective to mitigate climate change. Earlier studies predicted changes in the atmospheric circulation system. These atmospheric feedbacks raise questions about the self-sustainability of such an intervention, but have not been investigated in detail. Here, we investigate changes in precipitation and circulation in response to Saharan large-scale afforestation and irrigation with NCAR's CESM-WACCM Earth system model. Our model results show a Saharan temperature reduction by 6 K and weak precipitation enhancement by 267 mm/year over the Sahara. Only 26% of the evapotranspirated water re-precipitates over the Saharan Desert, considerably large amounts are advected southward to the Sahel zone and enhance the West African monsoon (WAM). Different processes cause circulation and precipitation changes over North Africa. The increase in atmospheric moisture leads to radiative cooling above the Sahara and increased high-level cloud coverage as well as atmospheric warming above the Sahel zone. Both lead to a circulation anomaly with descending air over the Sahara and ascending air over the Sahel zone. Together with changes in the meridional temperature gradient, this results in a southward shift of the inner-tropical front. The strengthening of the Tropical easterly jet and the northward displacement of the African easterly jet is associated with a northward displacement and strengthening of the WAM precipitation. Our results suggest complex atmospheric circulation feedbacks, which reduce the precipitation potential over an afforested Sahara and enhance WAM precipitation.

  1. Genetic Engineering of a Radiation-Resistant Bacterium for Biodegradation of Mixed Wastes--Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Mary E. Lidstrom

    2003-12-26

    Aqueous mixed low level wastes (MLLW) containing radionuclides, solvents, and/or heavy metals represent a serious current and future problem for DOE environmental management and cleanup. In order to provide low-cost treatment alternatives under mild conditions for such contained wastes, we have proposed to use the radiation-resistant bacterium, Deinococcus radiodurans. This project has focused on developing D. radiodurans strains for dual purpose processes: cometabolic treatment of haloorganics and other solvents and removal of heavy metals from waste streams in an above-ground reactor system. The characteristics of effective treatment strains that must be attained are: (a) high biodegradative and metal binding activity; (b) stable treatment characteristics in the absence of selection and in the presence of physiological stress; (c) survival and activity under harsh chemical conditions, including radiation. The result of this project has been a suite of strains with high biodegradative capabilities that are candidates for pilot stage treatment systems. In addition, we have determined how to create conditions to precipitate heavy metals on the surface of the bacterium, as the first step towards creating dual-use treatment strains for contained mixed wastes of importance to the DOE. Finally, we have analyzed stress response in this bacterium, to create the foundation for developing treatment processes that maximize degradation while optimizing survival under high stress conditions.

  2. Comparative genomics of Thermus thermophilus and Deinococcus radiodurans: divergent routes of adaptation to thermophily and radiation resistance

    Directory of Open Access Journals (Sweden)

    Daly Michael J

    2005-10-01

    Full Text Available Abstract Background Thermus thermophilus and Deinococcus radiodurans belong to a distinct bacterial clade but have remarkably different phenotypes. T. thermophilus is a thermophile, which is relatively sensitive to ionizing radiation and desiccation, whereas D. radiodurans is a mesophile, which is highly radiation- and desiccation-resistant. Here we present an in-depth comparison of the genomes of these two related but differently adapted bacteria. Results By reconstructing the evolution of Thermus and Deinococcus after the divergence from their common ancestor, we demonstrate a high level of post-divergence gene flux in both lineages. Various aspects of the adaptation to high temperature in Thermus can be attributed to horizontal gene transfer from archaea and thermophilic bacteria; many of the horizontally transferred genes are located on the single megaplasmid of Thermus. In addition, the Thermus lineage has lost a set of genes that are still present in Deinococcus and many other mesophilic bacteria but are not common among thermophiles. By contrast, Deinococcus seems to have acquired numerous genes related to stress response systems from various bacteria. A comparison of the distribution of orthologous genes among the four partitions of the Deinococcus genome and the two partitions of the Thermus genome reveals homology between the Thermus megaplasmid (pTT27 and Deinococcus megaplasmid (DR177. Conclusion After the radiation from their common ancestor, the Thermus and Deinococcus lineages have taken divergent paths toward their distinct lifestyles. In addition to extensive gene loss, Thermus seems to have acquired numerous genes from thermophiles, which likely was the decisive contribution to its thermophilic adaptation. By contrast, Deinococcus lost few genes but seems to have acquired many bacterial genes that apparently enhanced its ability to survive different kinds of environmental stresses. Notwithstanding the accumulation of

  3. Biofilms and planktonic cells of Deinococcus geothermalis in extreme environments

    Science.gov (United States)

    Panitz, Corinna; Reitz, Guenther; Rabbow, Elke; Rettberg, Petra; Flemming, Hans-Curt; Wingender, Jost; Froesler, Jan

    In addition to the several extreme environments on Earth, Space can be considered as just another exceptional environment with a unique mixture of stress factors comprising UV radiation, vacuum, desiccation, temperature, ionizing radiation and microgravity. Life that processes in these environments can depend on the life forms and their state of living. The question is whether there are different strategies for individual microorganisms compared to communities of the same organisms to cope with the different factors of their surroundings. Comparative studies of the survi-val of these communities called biofilms and planktonic cell samples of Deinococcus geothermalis stand at the focal point of the presented investigations. A biofilm is a structured community of microorganisms that live encapsulated in a matrix of extracellular polymeric substances on a surface. Microorganisms living in a biofilm usually have significantly different properties to cooperate than individually living microorganisms of the same species. An advantage of the biofilm is increased resistance to various chemical and physical effects, while the dense extracellular matrix and the outer layer of the cells protect the interior of the microbial consortium. The space experiment BOSS (Biofilm organisms surfing Space) as part the ESA experimental unit EXPOSE R-2 with a planned launch date in July 2014 will be subsequently mounted on the Russian Svesda module outside the ISS. An international team of scientists coordinated by Dr. P. Rettberg will investigate the hypothesis whether microorganisms organized as biofilm outmatch the same microorganisms exposed individually in the long-term survival of the harsh environmental conditions as they occur in space and on Mars. Another protective function in the samples could be dust par-ticles for instance Mars regolith simulant contained inside the biofilms or mixed with the planktonic cells, as additional shelter especially against the extraterrestrial UV

  4. Responses of Mn2+ speciation in Deinococcus radiodurans and Escherichia coli to γ-radiation by advanced paramagnetic resonance methods.

    Science.gov (United States)

    Sharma, Ajay; Gaidamakova, Elena K; Matrosova, Vera Y; Bennett, Brian; Daly, Michael J; Hoffman, Brian M

    2013-04-09

    The remarkable ability of bacterium Deinococcus radiodurans to survive extreme doses of γ-rays (12,000 Gy), 20 times greater than Escherichia coli, is undiminished by loss of Mn-dependent superoxide dismutase (SodA). D. radiodurans radiation resistance is attributed to the accumulation of low-molecular-weight (LMW) "antioxidant" Mn(2+)-metabolite complexes that protect essential enzymes from oxidative damage. However, in vivo information about such complexes within D. radiodurans cells is lacking, and the idea that they can supplant reactive-oxygen-species (ROS)-scavenging enzymes remains controversial. In this report, measurements by advanced paramagnetic resonance techniques [electron-spin-echo (ESE)-EPR/electron nuclear double resonance/ESE envelope modulation (ESEEM)] reveal differential details of the in vivo Mn(2+) speciation in D. radiodurans and E. coli cells and their responses to 10 kGy γ-irradiation. The Mn(2+) of D. radiodurans exists predominantly as LMW complexes with nitrogenous metabolites and orthophosphate, with negligible EPR signal from Mn(2+) of SodA. Thus, the extreme radiation resistance of D. radiodurans cells cannot be attributed to SodA. Correspondingly, 10 kGy irradiation causes no change in D. radiodurans Mn(2+) speciation, despite the paucity of holo-SodA. In contrast, the EPR signal of E. coli is dominated by signals from low-symmetry enzyme sites such as that of SodA, with a minority pool of LMW Mn(2+) complexes that show negligible coordination by nitrogenous metabolites. Nonetheless, irradiation of E. coli majorly changes LMW Mn(2+) speciation, with extensive binding of nitrogenous ligands created by irradiation. We infer that E. coli is highly susceptible to radiation-induced ROS because it lacks an adequate supply of LMW Mn antioxidants.

  5. Functional Characterization of the Role of the Chromosome I Partitioning System in Genome Segregation in Deinococcus radiodurans

    Science.gov (United States)

    Charaka, Vijay Kumar

    2012-01-01

    Deinococcus radiodurans, a radiation-resistant bacterium, harbors a multipartite genome. Chromosome I contains three putative centromeres (segS1, segS2, and segS3), and ParA (ParA1) and ParB (ParB1) homologues. The ParB1 interaction with segS was sequence specific, and ParA1 was shown to be a DNA binding ATPase. The ATPase activity of ParA1 was stimulated when segS elements were coincubated with ParB1, but the greatest increase was observed with segS3. ParA1 incubated with the segS-ParB1 complex showed increased light scattering in the absence of ATP. In the presence of ATP, this increase was continued with segS1-ParA1B1 and segS2-ParA1B1 complexes, while it decreased rapidly after an initial increase for 30 min in the case of segS3. D. radiodurans cells expressing green fluorescent protein (GFP)-ParB1 produced foci on nucleoids, and the ΔparB1 mutant showed growth retardation and ∼13%-higher anucleation than the wild type. Unstable mini-F plasmids carrying segS1 and segS2 showed inheritance in Escherichia coli without ParA1B1, while segS3-mediated plasmid stability required the in trans expression of ParA1B1. Unlike untransformed E. coli cells, cells harboring pDAGS3, a plasmid carrying segS3 and also expressing ParB1-GFP, produced discrete GFP foci on nucleoids. These findings suggested that both segS elements and the ParA1B1 proteins of D. radiodurans are functionally active and have a role in genome segregation. PMID:22843847

  6. Structure and Cellular Dynamics of Deinococcus radiodurans Single-stranded DNA (ssDNA)-binding Protein (SSB)-DNA Complexes*

    Science.gov (United States)

    George, Nicholas P.; Ngo, Khanh V.; Chitteni-Pattu, Sindhu; Norais, Cédric A.; Battista, John R.; Cox, Michael M.; Keck, James L.

    2012-01-01

    The single-stranded DNA (ssDNA)-binding protein from the radiation-resistant bacterium Deinococcus radiodurans (DrSSB) functions as a homodimer in which each monomer contains two oligonucleotide-binding (OB) domains. This arrangement is exceedingly rare among bacterial SSBs, which typically form homotetramers of single-OB domain subunits. To better understand how this unusual structure influences the DNA binding and biological functions of DrSSB in D. radiodurans radiation resistance, we have examined the structure of DrSSB in complex with ssDNA and the DNA damage-dependent cellular dynamics of DrSSB. The x-ray crystal structure of the DrSSB-ssDNA complex shows that ssDNA binds to surfaces of DrSSB that are analogous to those mapped in homotetrameric SSBs, although there are distinct contacts in DrSSB that mediate species-specific ssDNA binding. Observations by electron microscopy reveal two salt-dependent ssDNA-binding modes for DrSSB that strongly resemble those of the homotetrameric Escherichia coli SSB, further supporting a shared overall DNA binding mechanism between the two classes of bacterial SSBs. In vivo, DrSSB levels are heavily induced following exposure to ionizing radiation. This accumulation is accompanied by dramatic time-dependent DrSSB cellular dynamics in which a single nucleoid-centric focus of DrSSB is observed within 1 h of irradiation but is dispersed by 3 h after irradiation. These kinetics parallel those of D. radiodurans postirradiation genome reconstitution, suggesting that DrSSB dynamics could play important organizational roles in DNA repair. PMID:22570477

  7. Deinococcus radiodurans YgjD and YeaZ are involved in the repair of DNA cross-links.

    Science.gov (United States)

    Onodera, Takefumi; Satoh, Katsuya; Ohta, Toshihiro; Narumi, Issay

    2013-01-01

    Orthologs of Escherichia coli ygjD and yeaZ genes are highly conserved in various organisms. The genome of the radioresistant bacterium Deinococcus radiodurans possesses single orthologs of ygjD (DR_0382) and yeaZ (DR_0756). Complete loss of either one or both genes did not result in any significant changes in cell growth efficiency, indicating that both genes are not essential for cell viability in D. radiodurans, unlike the case with other species such as E. coli, Bacillus subtilis and Saccharomyces cerevisiae. Survival rates following DNA damage induced by hydrogen peroxide (H(2)O(2)), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), ultra violet (UV) radiation, γ-rays, cisplatin and mitomycin C (MMC) were compared among the wild-type strain and D. radiodurans ygjD/yeaZ null mutants. Cell viability of the null mutants did not decrease following exposure to H(2)O(2) or MNNG. In addition, the reduction in cell viability following exposure to γ-rays, UV radiation or cisplatin was marginal in the null mutants compared to the wild-type strain. Interestingly, the null mutants exhibited high sensitivity to MMC, which mainly causes interstrand DNA cross-links. The sensitivity of the null mutants to MMC was restored to that of the wild type by transformation with plasmids expressing these genes. These results suggest that D. radiodurans ygjD and yeaZ genes are involved in DNA repair and play a role in the repair of DNA cross-links.

  8. SAXS Structural Studies of Dps from Deinococcus radiodurans Highlights the Conformation of the Mobile N-Terminal Extensions.

    Science.gov (United States)

    Santos, Sandra P; Cuypers, Maxime G; Round, Adam; Finet, Stephanie; Narayanan, Theyencheri; Mitchell, Edward P; Romão, Célia V

    2017-03-10

    The radiation-resistant bacterium Deinococcus radiodurans contains two DNA-binding proteins from starved cells (Dps): Dps1 (DR2263) and Dps2 (DRB0092). These are suggested to play a role in DNA interaction and manganese and iron storage. The proteins assemble as a conserved dodecameric structure with structurally uncharacterised N-terminal extensions. In the case of DrDps1, these extensions have been proposed to be involved in DNA interactions, while in DrDps2, their function has yet to be established. The reported data reveal the relative position of the N-terminal extensions to the dodecameric sphere in solution for both Dps. The low-resolution small angle X-ray scattering (SAXS) results show that the N-terminal extensions protrude from the spherical shell of both proteins. The SAXS envelope of a truncated form of DrDps1 without the N-terminal extensions appears as a dodecameric sphere, contrasting strongly with the protrusions observed in the full-length models. The effect of iron incorporation into DrDps2 was investigated by static and stopped-flow SAXS measurements, revealing dynamic structural changes upon iron binding and core formation, as reflected by a quick alteration of its radius of gyration. The truncated and full-length versions of DrDps were also compared on the basis of their interaction with DNA to analyse functional roles of the N-terminal extensions. DrDps1 N-terminal protrusions appear to be directly involved with DNA, whilst those from DrDps2 are indirectly associated with DNA binding. Furthermore, detection of DrDps2 in the D. radiodurans membrane fraction suggests that the N-terminus of the protein interacts with the membrane. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. PprM, a Cold Shock Domain-Containing Protein from Deinococcus radiodurans, Confers Oxidative Stress Tolerance to Escherichia coli.

    Science.gov (United States)

    Park, Sun-Ha; Singh, Harinder; Appukuttan, Deepti; Jeong, Sunwook; Choi, Yong Jun; Jung, Jong-Hyun; Narumi, Issay; Lim, Sangyong

    2016-01-01

    Escherichia coli is a representative microorganism that is frequently used for industrial biotechnology; thus its cellular robustness should be enhanced for the widespread application of E. coli in biotechnology. Stress response genes from the extremely radioresistant bacterium Deinococcus radiodurans have been used to enhance the stress tolerance of E. coli. In the present study, we introduced the cold shock domain-containing protein PprM from D. radiodurans into E. coli and observed that the tolerance to hydrogen peroxide (H2O2) was significantly increased in recombinant strains (Ec-PprM). The overexpression of PprM in E. coli elevated the expression of some OxyR-dependent genes, which play important roles in oxidative stress tolerance. Particularly, mntH (manganese transporter) was activated by 9-fold in Ec-PprM, even in the absence of H2O2 stress, which induced a more than 2-fold increase in the Mn/Fe ratio compared with wild type. The reduced production of highly reactive hydroxyl radicals (·OH) and low protein carbonylation levels (a marker of oxidative damage) in Ec-PprM indicate that the increase in the Mn/Fe ratio contributes to the protection of cells from H2O2 stress. PprM also conferred H2O2 tolerance to E. coli in the absence of OxyR. We confirmed that the H2O2 tolerance of oxyR mutants reflected the activation of the ycgZ-ymgABC operon, whose expression is activated by H2O2 in an OxyR-independent manner. Thus, the results of the present study showed that PprM could be exploited to improve the robustness of E. coli.

  10. Crystal structure of the DNA polymerase III β subunit (β-clamp) from the extremophile Deinococcus radiodurans.

    Science.gov (United States)

    Niiranen, Laila; Lian, Kjersti; Johnson, Kenneth A; Moe, Elin

    2015-02-27

    Deinococcus radiodurans is an extremely radiation and desiccation resistant bacterium which can tolerate radiation doses up to 5,000 Grays without losing viability. We are studying the role of DNA repair and replication proteins for this unusual phenotype by a structural biology approach. The DNA polymerase III β subunit (β-clamp) acts as a sliding clamp on DNA, promoting the binding and processivity of many DNA-acting proteins, and here we report the crystal structure of D. radiodurans β-clamp (Drβ-clamp) at 2.0 Å resolution. The sequence verification process revealed that at the time of the study the gene encoding Drβ-clamp was wrongly annotated in the genome database, encoding a protein of 393 instead of 362 amino acids. The short protein was successfully expressed, purified and used for crystallisation purposes in complex with Cy5-labeled DNA. The structure, which was obtained from blue crystals, shows a typical ring-shaped bacterial β-clamp formed of two monomers, each with three domains of identical topology, but with no visible DNA in electron density. A visualisation of the electrostatic surface potential reveals a highly negatively charged outer surface while the inner surface and the dimer forming interface have a more even charge distribution. The structure of Drβ-clamp was determined to 2.0 Å resolution and shows an evenly distributed electrostatic surface charge on the DNA interacting side. We hypothesise that this charge distribution may facilitate efficient movement on encircled DNA and help ensure efficient DNA metabolism in D. radiodurans upon exposure to high doses of ionizing irradiation or desiccation.

  11. PprM, a Cold Shock Domain-Containing Protein from Deinococcus radiodurans, Confers Oxidative Stress Tolerance to Escherichia coli

    Science.gov (United States)

    Park, Sun-Ha; Singh, Harinder; Appukuttan, Deepti; Jeong, Sunwook; Choi, Yong Jun; Jung, Jong-Hyun; Narumi, Issay; Lim, Sangyong

    2017-01-01

    Escherichia coli is a representative microorganism that is frequently used for industrial biotechnology; thus its cellular robustness should be enhanced for the widespread application of E. coli in biotechnology. Stress response genes from the extremely radioresistant bacterium Deinococcus radiodurans have been used to enhance the stress tolerance of E. coli. In the present study, we introduced the cold shock domain-containing protein PprM from D. radiodurans into E. coli and observed that the tolerance to hydrogen peroxide (H2O2) was significantly increased in recombinant strains (Ec-PprM). The overexpression of PprM in E. coli elevated the expression of some OxyR-dependent genes, which play important roles in oxidative stress tolerance. Particularly, mntH (manganese transporter) was activated by 9-fold in Ec-PprM, even in the absence of H2O2 stress, which induced a more than 2-fold increase in the Mn/Fe ratio compared with wild type. The reduced production of highly reactive hydroxyl radicals (·OH) and low protein carbonylation levels (a marker of oxidative damage) in Ec-PprM indicate that the increase in the Mn/Fe ratio contributes to the protection of cells from H2O2 stress. PprM also conferred H2O2 tolerance to E. coli in the absence of OxyR. We confirmed that the H2O2 tolerance of oxyR mutants reflected the activation of the ycgZ-ymgABC operon, whose expression is activated by H2O2 in an OxyR-independent manner. Thus, the results of the present study showed that PprM could be exploited to improve the robustness of E. coli. PMID:28119668

  12. The structure of amylosucrase from Deinococcus radiodurans has an unusual open active-site topology

    DEFF Research Database (Denmark)

    Skov, Lars K; Pizzut-Serin, Sandra; Remaud-Simeon, Magali

    2013-01-01

    Amylosucrases (ASes) catalyze the formation of an α-1,4-glucosidic linkage by transferring a glucosyl unit from sucrose onto an acceptor α-1,4-glucan. To date, several ligand-bound crystal structures of wild-type and mutant ASes from Neisseria polysaccharea and Deinococcus geothermalis have been...

  13. Identifying the Proteins that Mediate the Ionizing Radiation Resistance of Deinococcus Radiodurans R1

    Energy Technology Data Exchange (ETDEWEB)

    Battista, John R

    2010-02-22

    The primary objectives of this proposal was to define the subset of proteins required for the ionizing radiation (IR) resistance of Deinococcus radiodurans R1, characterize the activities of those proteins, and apply what was learned to problems of interest to the Department of Energy.

  14. Fluorescence properties of the chromophore-binding domain of bacteriophytochrome from Deinococcus radiodurans

    NARCIS (Netherlands)

    Lehtivuori, Heli; Rissanen, Ilona; Takala, Heikki; Bamford, Jaana K H; Tkachenko, Nikolai V.; Ihalainen, Janne A.

    2013-01-01

    Fluorescent proteins are versatile tools for molecular imaging. In this study, we report a detailed analysis of the absorption and fluorescence properties of the chromophore-binding domain from Deinococcus radiodurans and its D207H mutant. Using single photon counting and transient absorption

  15. PprA Protein Is Involved in Chromosome Segregation via Its Physical and Functional Interaction with DNA Gyrase in Irradiated Deinococcus radiodurans Bacteria

    Science.gov (United States)

    Devigne, Alice; Guérin, Philippe; Lisboa, Johnny; Quevillon-Cheruel, Sophie; Armengaud, Jean; Sommer, Suzanne; Bouthier de la Tour, Claire

    2016-01-01

    ABSTRACT PprA, a radiation-induced Deinococcus-specific protein, was previously shown to be required for cell survival and accurate chromosome segregation after exposure to ionizing radiation. Here, we used an in vivo approach to determine, by shotgun proteomics, putative PprA partners coimmunoprecipitating with PprA when cells were exposed to gamma rays. Among them, we found the two subunits of DNA gyrase and, thus, chose to focus our work on characterizing the activities of the deinococcal DNA gyrase in the presence or absence of PprA. Loss of PprA rendered cells hypersensitive to novobiocin, an inhibitor of the B subunit of DNA gyrase. We showed that treatment of bacteria with novobiocin resulted in induction of the radiation desiccation response (RDR) regulon and in defects in chromosome segregation that were aggravated by the absence of PprA. In vitro, the deinococcal DNA gyrase, like other bacterial DNA gyrases, possesses DNA negative supercoiling and decatenation activities. These two activities are inhibited in vitro by novobiocin and nalidixic acid, whereas PprA specifically stimulates the decatenation activity of DNA gyrase. Together, these results suggest that PprA plays a major role in chromosome decatenation via its interaction with the deinococcal DNA gyrase when D. radiodurans cells are recovering from exposure to ionizing radiation. IMPORTANCE D. radiodurans is one of the most radiation-resistant organisms known. This bacterium is able to cope with high levels of DNA lesions generated by exposure to extreme doses of ionizing radiation and to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Here, we identified partners of PprA, a radiation-induced Deinococcus-specific protein, previously shown to be required for radioresistance. Our study leads to three main findings: (i) PprA interacts with DNA gyrase after irradiation, (ii) treatment of cells with novobiocin results in defects in chromosome segregation

  16. PprA Protein Is Involved in Chromosome Segregation via Its Physical and Functional Interaction with DNA Gyrase in Irradiated Deinococcus radiodurans Bacteria.

    Science.gov (United States)

    Devigne, Alice; Guérin, Philippe; Lisboa, Johnny; Quevillon-Cheruel, Sophie; Armengaud, Jean; Sommer, Suzanne; Bouthier de la Tour, Claire; Servant, Pascale

    2016-01-01

    PprA, a radiation-induced Deinococcus-specific protein, was previously shown to be required for cell survival and accurate chromosome segregation after exposure to ionizing radiation. Here, we used an in vivo approach to determine, by shotgun proteomics, putative PprA partners coimmunoprecipitating with PprA when cells were exposed to gamma rays. Among them, we found the two subunits of DNA gyrase and, thus, chose to focus our work on characterizing the activities of the deinococcal DNA gyrase in the presence or absence of PprA. Loss of PprA rendered cells hypersensitive to novobiocin, an inhibitor of the B subunit of DNA gyrase. We showed that treatment of bacteria with novobiocin resulted in induction of the radiation desiccation response (RDR) regulon and in defects in chromosome segregation that were aggravated by the absence of PprA. In vitro, the deinococcal DNA gyrase, like other bacterial DNA gyrases, possesses DNA negative supercoiling and decatenation activities. These two activities are inhibited in vitro by novobiocin and nalidixic acid, whereas PprA specifically stimulates the decatenation activity of DNA gyrase. Together, these results suggest that PprA plays a major role in chromosome decatenation via its interaction with the deinococcal DNA gyrase when D. radiodurans cells are recovering from exposure to ionizing radiation. IMPORTANCE D. radiodurans is one of the most radiation-resistant organisms known. This bacterium is able to cope with high levels of DNA lesions generated by exposure to extreme doses of ionizing radiation and to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Here, we identified partners of PprA, a radiation-induced Deinococcus-specific protein, previously shown to be required for radioresistance. Our study leads to three main findings: (i) PprA interacts with DNA gyrase after irradiation, (ii) treatment of cells with novobiocin results in defects in chromosome segregation that are

  17. Fennec dust forecast intercomparison over the Sahara in June 2011

    Directory of Open Access Journals (Sweden)

    J.-P. Chaboureau

    2016-06-01

    Full Text Available In the framework of the Fennec international programme, a field campaign was conducted in June 2011 over the western Sahara. It led to the first observational data set ever obtained that documents the dynamics, thermodynamics and composition of the Saharan atmospheric boundary layer (SABL under the influence of the heat low. In support to the aircraft operation, four dust forecasts were run daily at low and high resolutions with convection-parameterizing and convection-permitting models, respectively. The unique airborne and ground-based data sets allowed the first ever intercomparison of dust forecasts over the western Sahara. At monthly scale, large aerosol optical depths (AODs were forecast over the Sahara, a feature observed by satellite retrievals but with different magnitudes. The AOD intensity was correctly predicted by the high-resolution models, while it was underestimated by the low-resolution models. This was partly because of the generation of strong near-surface wind associated with thunderstorm-related density currents that could only be reproduced by models representing convection explicitly. Such models yield emissions mainly in the afternoon that dominate the total emission over the western fringes of the Adrar des Iforas and the Aïr Mountains in the high-resolution forecasts. Over the western Sahara, where the harmattan contributes up to 80 % of dust emission, all the models were successful in forecasting the deep well-mixed SABL. Some of them, however, missed the large near-surface dust concentration generated by density currents and low-level winds. This feature, observed repeatedly by the airborne lidar, was partly forecast by one high-resolution model only.

  18. The Green Sahara: Climate Change, Hydrologic History and Human Occupation

    Science.gov (United States)

    Blom, Ronald G.; Farr, Tom G.; Feynmann, Joan; Ruzmaikin, Alexander; Paillou, Philippe

    2009-01-01

    Archaeology can provide insight into interactions of climate change and human activities in sensitive areas such as the Sahara, to the benefit of both disciplines. Such analyses can help set bounds on climate change projections, perhaps identify elements of tipping points, and provide constraints on models. The opportunity exists to more precisely constrain the relationship of natural solar and climate interactions, improving understanding of present and future anthropogenic forcing. We are beginning to explore the relationship of human occupation of the Sahara and long-term solar irradiance variations synergetic with changes in atmospheric-ocean circulation patterns. Archaeological and climate records for the last 12 K years are gaining adequate precision to make such comparisons possible. We employ a range of climate records taken over the globe (e.g. Antarctica, Greenland, Cariaco Basin, West African Ocean cores, records from caves) to identify the timing and spatial patterns affecting Saharan climate to compare with archaeological records. We see correlation in changing ocean temperature patterns approx. contemporaneous with drying of the Sahara approx. 6K years BP. The role of radar images and other remote sensing in this work includes providing a geographically comprehensive geomorphic overview of this key area. Such coverage is becoming available from the Japanese PALSAR radar system, which can guide field work to collect archaeological and climatic data to further constrain the climate change chronology and link to models. Our initial remote sensing efforts concentrate on the Gilf Kebir area of Egypt.

  19. Characterizing the Catalytic Potential of Deinococcus, Arthrobacter and other Robust Bacteria in Contaminated Subsurface Environments of the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Daly, Michael J.

    2007-07-23

    Progress is briefly summarized in these areas: ionizing radiation resistance in bacteria; a hypothesis regarding ionizing radiation resistance emerging for bacterial cells; transcriptome analysis of irradiated D. radiodurans and Shewanella oneidensis; the role of metal reduction in Mn-dependnet Deinococcal species; and engineered Deinococcus strains as models for bioremediation. Key findings are also reported regarding protein oxidation as a possible key to bacterial desiccation resistance, and the whole-genome sequence of the thermophile Deinococcus geothermalis.

  20. Identification of distinctive molecular traits that are characteristic of the phylum "Deinococcus-Thermus" and distinguish its main constituent groups.

    Science.gov (United States)

    Ho, Jonathan; Adeolu, Mobolaji; Khadka, Bijendra; Gupta, Radhey S

    2016-10-01

    The phylum "Deinococcus-Thermus" contains two heavily researched groups of extremophilic bacteria: the highly radioresistant order Deinococcales and the thermophilic order Thermales. Very few characteristics are known that are uniquely shared by members of the phylum "Deinococcus-Thermus". Comprehensive phylogenetic and comparative analyses of >65 "Deinococcus-Thermus" genomes reported here have identified numerous molecular signatures in the forms of conserved signature insertions/deletions (CSIs) and conserved signature proteins (CSPs), which provide distinguishing characteristics of the phylum "Deinococcus-Thermus" and its main groups. We have identified 58 unique CSIs and 155 unique CSPs that delineate different phylogenetic groups within the phylum. Of these identified traits, 24 CSIs and 29 CSPs are characteristic of the phylum "Deinococcus-Thermus" and they provide novel and reliable means to circumscribe/describe this phylum. An additional 3 CSIs and 3 CSPs are characteristic of the order Deinococcales, and 6 CSIs and 51 CSPs are characteristic of the order Thermales. The remaining 25 CSIs and 72 CSPs identified in this study are distinctive traits of genus level groups within the phylum "Deinococcus-Thermus". The molecular characteristics identified in this work provide novel and independent support for the common ancestry of the members of the phylum "Deinococcus-Thermus" and provide a new means to distinguish the main constituent clades of the phylum. Additionally, the CSIs and CSPs identified in this work may play a role in the unique extremophilic adaptations of the members of this phylum and further functional analyses of these characteristics could provide novel biochemical insights into the unique adaptations found within the phylum "Deinococcus-Thermus". Copyright © 2016 Elsevier GmbH. All rights reserved.

  1. Conservation and diversity of the IrrE/DdrO-controlled radiation response in radiation-resistant Deinococcus bacteria.

    Science.gov (United States)

    Blanchard, Laurence; Guérin, Philippe; Roche, David; Cruveiller, Stéphane; Pignol, David; Vallenet, David; Armengaud, Jean; de Groot, Arjan

    2017-08-01

    The extreme radiation resistance of Deinococcus bacteria requires the radiation-stimulated cleavage of protein DdrO by a specific metalloprotease called IrrE. DdrO is the repressor of a predicted radiation/desiccation response (RDR) regulon, composed of radiation-induced genes having a conserved DNA motif (RDRM) in their promoter regions. Here, we showed that addition of zinc ions to purified apo-IrrE, and short exposure of Deinococcus cells to zinc ions, resulted in cleavage of DdrO in vitro and in vivo, respectively. Binding of IrrE to RDRM-containing DNA or interaction of IrrE with DNA-bound DdrO was not observed. The data are in line with IrrE being a zinc peptidase, and indicate that increased zinc availability, caused by oxidative stress, triggers the in vivo cleavage of DdrO unbound to DNA. Transcriptomics and proteomics of Deinococcus deserti confirmed the IrrE-dependent regulation of predicted RDR regulon genes and also revealed additional members of this regulon. Comparative analysis showed that the RDR regulon is largely well conserved in Deinococcus species, but also showed diversity in the regulon composition. Notably, several RDR genes with an important role in radiation resistance in Deinococcus radiodurans, for example pprA, are not conserved in some other radiation-resistant Deinococcus species. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  2. PprA, a pleiotropic protein for radioresistance, works through DNA gyrase and shows cellular dynamics during postirradiation recovery in Deinococcus radiodurans.

    Science.gov (United States)

    Kota, Swathi; Charaka, Vijaya Kumar; Misra, H S

    2014-08-01

    PprA, a pleiotropic protein involved in radioresistance of Deinococcus radiodurans was detected in multiprotein DNA processing complex identified from this bacterium. pprA mutant expressing GFP-PprA could restore its wild type resistance of γ radiation. Under normal conditions, GFP-PprA expressing cells showed PprA localization on both septum trapped nucleoids (STN) and nucleoids located elsewhere (MCN). Cell exposed to 4 kGy γ radiation showed nearly 2 h growth lag and during this growth arrest phase, the majority of the cells had GFP-PprA located on MCN. While in late phase (~120 min) PIR cells, when cells are nearly out of growth arrest, PprA was maximally found with STN. These cells when treated with nalidixic acid showed diffused localization of PprA across the septum. gyrA disruption mutant of D. radiodurans showed growth inhibition, which increased further in gyrA pprA mutant. Interestingly, gyrA mutant showed ~20-fold less resistance to γ radiation as compared to wild type, which did increase further in gyrA pprA mutant. These results suggested that PprA localization undergoes a dynamic change during PIR, and its localization on nucleoid near septum and functional interaction with gyrase A might suggest a mechanism that could explain PprA role in genome segregation possibly through topoisomerase II.

  3. Sud du Sahara | Page 5 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Sud du Sahara. Read more about Youth Employment and Migration in West Africa. Langue English. Read more about Évolution démographique asymétrique et gouvernance financière mondiale. Langue French. Read more about Asymmetric Demography and Global Financial Governance. Langue English.

  4. Conflict resolution in Western Sahara | Solà-Martín | African Journal ...

    African Journals Online (AJOL)

    This paper examines the democratisation agenda laid out by Western governments for the North African region vis-à-vis their Realpolitik conflict containment approach towards the Western Sahara conflict. Western policymakers conceive the United Nations Mission for the Referendum in Western Sahara as a safety net that ...

  5. Sud du Sahara | Page 95 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Sud du Sahara. Read more about Modèle d'édition et autre modèle d'octroi de licences (PALM Africa). Langue French. Read more about Publishing and Alternative Licensing Model of Africa (PALM Africa). Langue English. Read more about Strategic Action Plan for ERNWACA - 2007-2011. Langue English.

  6. Sud du Sahara | Page 96 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Sud du Sahara. Read more about Implementation of an Electronic Strategy in Bénin. Langue English. Read more about E-Stratégie du Bénin : programme de recherches multidisciplinaires d'appui à sa mise en oeuvre. Langue French. Read more about Libéralisation du commerce des biens et services TIC ...

  7. Sud du Sahara | Page 108 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Sud du Sahara. Read more about Understanding Obstacles to Peace in the Great Lakes Region : Actors, Interests and Strategies. Langue English. Read more about Comprendre les obstacles à la paix dans la région des Grands Lacs : acteurs, intérêts et stratégies. Langue French. Read more about ...

  8. Sud du Sahara | Page 55 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Sud du Sahara. Read more about Strengthening the Health System through a Maternal Death Review (Kenya and Zimbabwe). Langue English. Read more about Taxes sur les cigarettes en Tanzanie. Langue French. Read more about Cigarette Taxation in Tanzania. Langue English. Read more about AIDS ...

  9. Sud du Sahara | Page 74 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Sud du Sahara. Read more about Bamboo Production : Livelihood Diversification for Smallholder Tobacco Farmers in South Nyanza, Kenya - Phase II. Langue English. Read more about Culture du bambou : diversification des moyens de subsistance des petits producteurs de tabac du sud de la province ...

  10. Optimal investment and indifference pricing when risk aversion is not monotone: SAHARA utility functions

    NARCIS (Netherlands)

    Chen, A.; Pelsser, A.; Vellekoop, M.

    2008-01-01

    Abstract. We develop a new class of utility functions, SAHARA utility, with the dis- tinguishing feature that they implement the assumption that agents may become less risk-averse for very low values of wealth. This means that SAHARA utility can be used to characterize risk gambling behavior of an

  11. Regime shifts in the Sahara and Sahel: interactions between ecological and climatic systems in northern Africa

    NARCIS (Netherlands)

    Foley, J.A.; Coe, M.T.; Scheffer, M.; Wang, G.L.

    2003-01-01

    The Sahara and Sahel regions of northern Africa have complex environmental histories punctuated by sudden and dramatic "regime shifts" in climate and ecological conditions. Here we review the current understanding of the causes and consequences of two environmental regime shifts in the Sahara and

  12. Sud du Sahara | Page 93 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sud du Sahara. Sud du Sahara. Read more about Renouvellement des modes de gouvernance : industries extractives et réduction de la pauvreté en Afrique. Langue French. Read more about Renewing Modes of Governance : Extractive Industries and the Reduction of Poverty in Africa. Langue English. Read more about ...

  13. Wars and conflicts in the Sahara-Sahel

    DEFF Research Database (Denmark)

    Walther, Olivier

    the traditional lines between what is local and global, military and civilian, domestic and international, politics and identity. The purpose of this paper is to analyse these patterns of violence. The first section presents the geographic distribution and development over time of the main sources of violence...... in North and West Africa before examining the events behind the increase in political violence in the Sahel and the Sahara. The second section analyses the patterns of violence, and focuses on the geographic scales thereof and the strategies of the warring parties. In its conclusion, the paper highlights...

  14. Extremes of Survival Achieved by the Radiophile Deinococcus Radiodurans: A Model for Microbial Life on Mars

    Science.gov (United States)

    Daly, M.; Sridhar, R.; Richmond, R.

    1999-01-01

    Deinococcus radiodurans is an extremophile in more than one defined way. First it is extreme in its resistance to freeze drying. Second it is probably uniquely extreme on Earth in its resistance to ionizing radiation. The polyextremophilic capacity of D. radiodurans will be considered. The selection pressures on Mars will then be considered in relation to D. radiodurans in order to support a hypothesis that if microbial life exists on Mars, then it likely includes polyextremophiles.

  15. Cyclic AMP Receptor Protein Acts as a Transcription Regulator in Response to Stresses in Deinococcus radiodurans

    OpenAIRE

    Su Yang; Hong Xu; Jiali Wang; Chengzhi Liu; Huizhi Lu; Mengjia Liu; Ye Zhao; Bing Tian; Liangyan Wang; Yuejin Hua

    2016-01-01

    The cyclic AMP receptor protein family of transcription factors regulates various metabolic pathways in bacteria, and also play roles in response to environmental changes. Here, we identify four homologs of the CRP family in Deinococcus radiodurans, one of which tolerates extremely high levels of oxidative stress and DNA-damaging reagents. Transcriptional levels of CRP were increased under hydrogen peroxide (H2O2) treatment during the stationary growth phase, indicating that CRPs function in ...

  16. Transcriptional analysis of Deinococcus radiodurans reveals novel small RNAs that are differentially expressed under ionizing radiation.

    Science.gov (United States)

    Tsai, Chen-Hsun; Liao, Rick; Chou, Brendan; Contreras, Lydia M

    2015-03-01

    Small noncoding RNAs (sRNAs) are posttranscriptional regulators that have been identified in multiple species and shown to play essential roles in responsive mechanisms to environmental stresses. The natural ability of specific bacteria to resist high levels of radiation has been of high interest to mechanistic studies of DNA repair and biomolecular protection. Deinococcus radiodurans is a model extremophile for radiation studies that can survive doses of ionizing radiation of >12,000 Gy, 3,000 times higher than for most vertebrates. Few studies have investigated posttranscriptional regulatory mechanisms of this organism that could be relevant in its general gene regulatory patterns. In this study, we identified 199 potential sRNA candidates in D. radiodurans by whole-transcriptome deep sequencing analysis and confirmed the expression of 41 sRNAs by Northern blotting and reverse transcriptase PCR (RT-PCR). A total of 8 confirmed sRNAs showed differential expression during recovery after acute ionizing radiation (15 kGy). We have also found and confirmed 7 sRNAs in Deinococcus geothermalis, a closely related radioresistant species. The identification of several novel sRNAs in Deinococcus bacteria raises important questions about the evolution and nature of global gene regulation in radioresistance. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  17. The three catalases in Deinococcus radiodurans: Only two show catalase activity.

    Science.gov (United States)

    Jeong, Sun-Wook; Jung, Jong-Hyun; Kim, Min-Kyu; Seo, Ho Seong; Lim, Heon-Man; Lim, Sangyong

    2016-01-15

    Deinococcus radiodurans, which is extremely resistant to ionizing radiation and oxidative stress, is known to have three catalases (DR1998, DRA0146, and DRA0259). In this study, to investigate the role of each catalase, we constructed catalase mutants (Δdr1998, ΔdrA0146, and ΔdrA0259) of D. radiodurans. Of the three mutants, Δdr1998 exhibited the greatest decrease in hydrogen peroxide (H2O2) resistance and the highest increase in intracellular reactive oxygen species (ROS) levels following H2O2 treatments, whereas ΔdrA0146 showed no change in its H2O2 resistance or ROS level. Catalase activity was not attenuated in ΔdrA0146, and none of the three bands detected in an in-gel catalase activity assay disappeared in ΔdrA0146. The purified His-tagged recombinant DRA0146 did not show catalase activity. In addition, the phylogenetic analysis of the deinococcal catalases revealed that the DR1998-type catalase is common in the genus Deinococcus, but the DRA0146-type catalase was found in only 4 of 23 Deinococcus species. Taken together, these results indicate that DR1998 plays a critical role in the anti-oxidative system of D. radiodurans by detoxifying H2O2, but DRA0146 does not have catalase activity and is not involved in the resistance to H2O2 stress. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Complete genome sequence of the orange-red pigmented, radioresistant Deinococcus proteolyticus type strain (MRPT)

    Energy Technology Data Exchange (ETDEWEB)

    Copeland, A [U.S. Department of Energy, Joint Genome Institute; Zeytun, Ahmet [Los Alamos National Laboratory (LANL); Yasawong, Montri [HZI - Helmholtz Centre for Infection Research, Braunschweig, Germany; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Lucas, Susan [U.S. Department of Energy, Joint Genome Institute; Hammon, Nancy [U.S. Department of Energy, Joint Genome Institute; Deshpande, Shweta [U.S. Department of Energy, Joint Genome Institute; Cheng, Jan-Fang [U.S. Department of Energy, Joint Genome Institute; Han, Cliff [Los Alamos National Laboratory (LANL); Tapia, Roxanne [Los Alamos National Laboratory (LANL); Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Liolios, Konstantinos [U.S. Department of Energy, Joint Genome Institute; Pagani, Ioanna [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Mikhailova, Natalia [U.S. Department of Energy, Joint Genome Institute; Pati, Amrita [U.S. Department of Energy, Joint Genome Institute; Chen, Amy [U.S. Department of Energy, Joint Genome Institute; Palaniappan, Krishna [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Hauser, Loren John [ORNL; Jeffries, Cynthia [Oak Ridge National Laboratory (ORNL); Brambilla, Evelyne-Marie [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Rohde, Manfred [HZI - Helmholtz Centre for Infection Research, Braunschweig, Germany; Sikorski, Johannes [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Pukall, Rudiger [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Goker, Markus [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Bristow, James [U.S. Department of Energy, Joint Genome Institute; Eisen, Jonathan [U.S. Department of Energy, Joint Genome Institute; Markowitz, Victor [U.S. Department of Energy, Joint Genome Institute; Hugenholtz, Philip [U.S. Department of Energy, Joint Genome Institute; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Klenk, Hans-Peter [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute

    2012-01-01

    Deinococcus proteolyticus (ex Kobatake et al. 1973) Brook and Murray 1981 is one of currently 47 species in the genus Deinococcus within the family Deinococcaceae. Strain MRPTT was isolated from faeces of Lama glama; it shares with various other species of the genus the extreme radiation resistance, with D. proteolyticus being resistant up to 1.5 Mrad of gamma radiation. Strain MRPT{sup T} is of further interest for its carotenoid pigment. The genome presented here is only the fifth completed genome sequence of a member of the genus Deinococcus (and the forth type strain) to be published, and will hopefully contribute to a better understanding of how members of this genus adapted to high gamma- or UV ionizing-radiation. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 2,886,836 bp long genome with its four large plasmids of 97 kbp, 132 kbp, 196 kbp and 315 kbp harbours 2,741 protein-coding and 58 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  19. Lactococcus lactis - a diploid bacterium

    DEFF Research Database (Denmark)

    Michelsen, Ole; Hansen, Flemming G.; Jensen, Peter Ruhdal

    In contrast to higher eukaryotes, bacteria are haploid, i.e. they store their genetic information in a single chromosome, which is then duplicated during the cell cycle. If the growth rate is sufficiently low, the bacterium is born with only a single copy of the chromosome, which gets duplicated...... the next division. Thus, the regions of the chromosome that are the last to be replicated are haploid even in fast-growing bacteria. In contrast to this general rule for bacteria, we found that Lactococcus lactis, a bacterium which has been exploited for thousands of years for the production of fermented...

  20. Eastern Sahara Geology from Orbital Radar: Potential Analog to Mars

    Science.gov (United States)

    Farr, T. G.; Paillou, P.; Heggy, E.

    2004-01-01

    Much of the surface of Mars has been intensely reworked by aeolian processes and key evidence about the history of the Martian environment seems to be hidden beneath a widespread layer of debris (paleo lakes and rivers, faults, impact craters). In the same way, the recent geological and hydrological history of the eastern Sahara is still mainly hidden under large regions of wind-blown sand which represent a possible terrestrial analog to Mars. The subsurface geology there is generally invisible to optical remote sensing techniques, but radar images obtained from the Shuttle Imaging Radar (SIR) missions were able to penetrate the superficial sand layer to reveal parts of paleohydrological networks in southern Egypt.

  1. Shock veins in the Sahara 02500 ordinary chondrite

    Science.gov (United States)

    Owocki, Krzysztof; Muszyński, Andrzej

    2012-08-01

    A specimen of the Sahara 02500 ordinary chondrite contains shock-produced veins consisting of recrystallised fine-grained pyroxenes that include small droplets of Ni-rich metal. Non-melted olivines and pyroxenes show planar deformations filled by shock-melted and -polluted metal and troilite. Shock-melted feldspathic glass is present close to the shock veins. Geothermometric estimations indicate that the meteorite locally experienced moderate shock metamorphism with a minimum local peak temperature above 1400°C, resulting in partial melting of Ca-poor pyroxene and full melting of feldspars, metal and sulphides. The mineral assemblage in the shock veins suggests a pressure during melt recrystallisation below 10 GPa.

  2. Dry Deposition from Sahara Sources Regions of Western Africa

    Directory of Open Access Journals (Sweden)

    B. Douaiba

    2014-01-01

    Full Text Available Sahara dust storms during March 2004 have attracted much attention from the dust-research community due to their intensity, wide coverage, and endurance. In the present work, the dry deposition mechanisms of mineral dust are analysed during an event on the 3 March 2004 over the Northwest African coast. This particular case was chosen based on the strong dry removal that occurred, rendering it ideal for examining the deposition processes. The simulation of synoptic conditions and dry deposition of four dust particles including clay, small silt, large silt, and sand was performed with Eta model, coupled with a desert dust cycle module. The results have been compared with surface data from weather stations in North Africa, data of dry metals from stations located in Gran Canaria, and various satellite images such as European Organization for the Exploitation of Meteorological Satellites and Moderate Resolution Imaging Spectroradiometer for the period in question.

  3. Notes on Old Stone Constructions of West and Central Sahara

    Directory of Open Access Journals (Sweden)

    Mark MILBURN

    2009-10-01

    Full Text Available RESUMEN: El presente trabajo trata acerca de la tumba de TIN-HUMAN, HOGGAR, y la describe presentándola en relacón con los «monumentos en capilla» de Négrine, Tafilalet y Oeste del Sahara. Además, incluye comentarios sobre la rareza de las tumbas rectangulares con habitaciones interiores. Se hace una razonable exposición de los «monumentos fusiformes», conectados con la tradición del tránsito por barco a la vida futura. La tumba de TIN-HINAN combina características de los monumentos en capilla o habitación con aquellas otras de «monumentos de deambulatorio complejo».ABSTRACT: This work deals with the tomb of Tin-Hinan, Hoggar, and describes it as presenting a relationship with the «monuments à chapelle» of Négrine, Tafilalet and West Sahara which also have very large chambers. It also includes a commentarity on the rarity of rectangular tombs with interior chambers. It proposes a reasonable explanation of the «fusiformes monuments» as being connected with a tradition of a journey by ship to the after-life (this being suggested by their very shape. The tomb of Tin-Hinan combines characteristics of the «monument à chapelle ou à chambre» with those of a «monument à déambulatoire complexe».

  4. The three catalases in Deinococcus radiodurans: Only two show catalase activity

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Sun-Wook [Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, 580-185 (Korea, Republic of); Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, 305-764 (Korea, Republic of); Jung, Jong-Hyun; Kim, Min-Kyu; Seo, Ho Seong [Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, 580-185 (Korea, Republic of); Lim, Heon-Man [Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, 305-764 (Korea, Republic of); Lim, Sangyong, E-mail: saylim@kaeri.re.kr [Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, 580-185 (Korea, Republic of)

    2016-01-15

    Deinococcus radiodurans, which is extremely resistant to ionizing radiation and oxidative stress, is known to have three catalases (DR1998, DRA0146, and DRA0259). In this study, to investigate the role of each catalase, we constructed catalase mutants (Δdr1998, ΔdrA0146, and ΔdrA0259) of D. radiodurans. Of the three mutants, Δdr1998 exhibited the greatest decrease in hydrogen peroxide (H{sub 2}O{sub 2}) resistance and the highest increase in intracellular reactive oxygen species (ROS) levels following H{sub 2}O{sub 2} treatments, whereas ΔdrA0146 showed no change in its H{sub 2}O{sub 2} resistance or ROS level. Catalase activity was not attenuated in ΔdrA0146, and none of the three bands detected in an in-gel catalase activity assay disappeared in ΔdrA0146. The purified His-tagged recombinant DRA0146 did not show catalase activity. In addition, the phylogenetic analysis of the deinococcal catalases revealed that the DR1998-type catalase is common in the genus Deinococcus, but the DRA0146-type catalase was found in only 4 of 23 Deinococcus species. Taken together, these results indicate that DR1998 plays a critical role in the anti-oxidative system of D. radiodurans by detoxifying H{sub 2}O{sub 2}, but DRA0146 does not have catalase activity and is not involved in the resistance to H{sub 2}O{sub 2} stress. - Highlights: • The dr1998 mutant strain lost 90% of its total catalase activity. • Increased ROS levels and decreased H{sub 2}O{sub 2} resistance were observed in dr1998 mutants. • Lack of drA0146 did not affect any oxidative stress-related phenotypes. • The purified DRA0146 did not show catalase activity.

  5. Crystallization of Wadsleyite and Ringwoodite in Sahara 98222, 00293, and 00350: Constraints on Shock Conditions

    Science.gov (United States)

    Fudge, C.; Hu, J.; Sharp, T. G.

    2015-07-01

    We report on the coexistence of wadsleyite and ringwoodite in transformed clasts within three ordinary chondrites: Sahara 98222, 00293 and 00350. High-pressure mineralogy is used to constrain conditions of the impact event on the parent body.

  6. Crystal structure of the RNA 2',3'-cyclic phosphodiesterase from Deinococcus radiodurans.

    Science.gov (United States)

    Han, Wanchun; Cheng, Jiahui; Zhou, Congli; Hua, Yuejin; Zhao, Ye

    2017-05-01

    2',3'-Cyclic phosphodiesterase (CPDase) homologues have been found in all domains of life and are involved in diverse RNA and nucleotide metabolisms. The CPDase from Deinococcus radiodurans was crystallized and the crystals diffracted to 1.6 Å resolution, which is the highest resolution currently known for a CPDase structure. Structural comparisons revealed that the enzyme is in an open conformation in the absence of substrate. Nevertheless, the active site is well formed, and the representative motifs interact with sulfate ion, which suggests a conserved catalytic mechanism.

  7. Comment on "Climate-driven ecosystem succession in the Sahara: the past 6000 years".

    Science.gov (United States)

    Brovkin, Victor; Claussen, Martin

    2008-11-28

    Kröpelin et al. (Research Articles, 9 May 2008, p. 765) interpreted a sediment record from Lake Yoa in the east-central part of North Africa as support for a weak biogeophysical climate-vegetation feedback in the Sahara during the mid-Holocene. We argue that the new data do not invalidate earlier modeling results on strong land-atmosphere coupling in the Western Sahara for which the Lake Yoa record is far less representative.

  8. Building Fit-for-Purpose Spatial Frameworks for Sustainable Land Governaqnce in Sub-Sahara Africa

    DEFF Research Database (Denmark)

    Enemark, Stig

    2013-01-01

    countries this countrywide spatial framework has been developed over centuries. In contrast, most developing countries have a cadastral coverage of less than 30 per cent of the country. This means that over 70 per cent of the land in many developing countries, such as the sub-Sahara region, is generally......, economic, legal, and social issues related to building such fit-for purpose spatial frameworks as a means of paving the way towards sustainable and land governance in Sub-Sahara Africa...

  9. Dr-FtsA, an actin homologue in Deinococcus radiodurans differentially affects Dr-FtsZ and Ec-FtsZ functions in vitro.

    Science.gov (United States)

    Modi, Kruti; Misra, Hari S

    2014-01-01

    The Deinococcus radiodurans genome encodes homologues of divisome proteins including FtsZ and FtsA. FtsZ of this bacterium (Dr-FtsZ) has been recently characterized. In this paper, we study FtsA of D. radiodurans (Dr-FtsA) and its involvement in regulation of FtsZ function. Recombinant Dr-FtsA showed neither ATPase nor GTPase activity and its polymerization was ATP dependent. Interestingly, we observed that Dr-FtsA, when compared with E. coli FtsA (Ec-FtsA), has lower affinity for both Dr-FtsZ and Ec-FtsZ. Also, Dr-FtsA showed differential effects on GTPase activity and sedimentation characteristics of Dr-FtsZ and Ec-FtsZ. For instance, Dr-FtsA stimulated GTPase activity of Dr-FtsZ while GTPase activity of Ec-FtsZ was reduced in the presence of Dr-FtsA. Stimulation of GTPase activity of Dr-FtsZ by Dr-FtsA resulted in depolymerization of Dr-FtsZ. Dr-FtsA effects on GTPase activity and polymerization/depolymerisation characteristics of Dr-FtsZ did not change significantly in the presence of ATP. Recombinant E. coli expressing Dr-FtsA showed cell division inhibition in spite of in trans expression of Dr-FtsZ in these cells. These results suggested that Dr-FtsA, although it lacks ATPase activity, is still functional and differentially affects Dr-FtsZ and Ec-FtsZ function in vitro.

  10. DR1769, a protein with N-terminal beta propeller repeats and a low-complexity hydrophilic tail, plays a role in desiccation tolerance of Deinococcus radiodurans.

    Science.gov (United States)

    Rajpurohit, Yogendra S; Misra, Hari S

    2013-09-01

    The Deinococcus radiodurans genome encodes five putative quinoproteins. Among these, the Δdr2518 and Δdr1769 mutants became sensitive to gamma radiation. DR2518 with beta propeller repeats in the C-terminal domain was characterized as a radiation-responsive serine/threonine protein kinase in this bacterium. DR1769 contains beta propeller repeats at the N terminus, while its C-terminal domain is a proline-rich disordered structure and constitutes a low-complexity hydrophilic region with aliphatic-proline dipeptide motifs. The Δdr1769 mutant showed nearly a 3-log cycle sensitivity to desiccation at 5% humidity compared to that of the wild type. Interestingly, the gamma radiation and mitomycin C (MMC) resistance in mutant cells also dropped by ∼1-log cycle at 10 kGy and ∼1.5-fold, respectively, compared to those in wild-type cells. But there was no effect of UV (254 nm) exposure up to 800 J · m(-2). These cells showed defective DNA double-strand break repair, and the average size of the nucleoid in desiccated wild-type and Δdr1769 cells was reduced by approximately 2-fold compared to that of respective controls. However, the nucleoid in wild-type cells returned to a size almost similar to that of the untreated control, which did not happen in mutant cells, at least up to 24 h postdesiccation. These results suggest that DR1769 plays an important role in desiccation and radiation resistance of D. radiodurans, possibly by protecting genome integrity under extreme conditions.

  11. THE ROLE OF IRON IN Deinococcus radiodurans ENGINEERED FOR GROWTH ON TOLUENE AND THE ROLE OF MANGANESE IN THE EXTREME RADIATION RESISTANCE PHENOTYPE

    Energy Technology Data Exchange (ETDEWEB)

    Hassan Brim; Elena K. Gaidamakova; Vera Y. Matrosova; Min Zhai; Amudhan Venkateswaran; Marina Omelchenko; Kira S. Makarova; Lawrence P. Wackett; James K. Fredrickson; Michael J. Daly

    2004-03-17

    Toluene and other fuel hydrocarbons are commonly found in association with radionuclides at numerous Department of Energy (DOE) sites, frequently occurring together with Cr(VI) and other heavy metals. In this study, the extremely radiation resistant bacterium Deinococcus radiodurans was engineered for complete toluene mineralization by cloned expression of tod and xyl genes of Pseudomonas putida. The recombinant Tod/Xyl strain showed significant incorporation of carbon from the toluene aromatic ring into cellular macromolecules and carbon dioxide, in the absence or presence of chronic radiation. We have shown that intracellular iron concentrations in wild-type D. radiodurans in minimal medium are exceptionally low and not sufficient to support growth on toluene using Fe-dependent oxygenases cloned from P. putida. Introducing the fur mutation into D. radiodurans increased intracellular Fe levels, and imparted on the engineered strain the ability to grow on meta-toluate as the sole carbon and energy source. The organism's native Cr(VI) reduction capabilities were facilitated by toluene when present as the sole carbon and energy source in natural sediment analogues of DOE contaminated environments. The engineered bacteria were able to oxidize toluene under both minimal and complex nutrient conditions, which is important since both conditions have environmental equivalents in the context of bioremediation processes. As such, the Tod/Xyl strain is providing a model for understanding the role of Fe and reduction of metals coupled to organic contaminant oxidation in aerobic radionuclide contaminated sediments. We have shown that D. radiodurans contains high intracellular manganese levels, and that Mn restriction sensitizes cells to irradiation. We propose that the unusually high Mn/Fe ratio of D. radiodurans facilitates survival by quenching oxidative stress during recovery.

  12. Dr-FtsA, an actin homologue in Deinococcus radiodurans differentially affects Dr-FtsZ and Ec-FtsZ functions in vitro.

    Directory of Open Access Journals (Sweden)

    Kruti Modi

    Full Text Available The Deinococcus radiodurans genome encodes homologues of divisome proteins including FtsZ and FtsA. FtsZ of this bacterium (Dr-FtsZ has been recently characterized. In this paper, we study FtsA of D. radiodurans (Dr-FtsA and its involvement in regulation of FtsZ function. Recombinant Dr-FtsA showed neither ATPase nor GTPase activity and its polymerization was ATP dependent. Interestingly, we observed that Dr-FtsA, when compared with E. coli FtsA (Ec-FtsA, has lower affinity for both Dr-FtsZ and Ec-FtsZ. Also, Dr-FtsA showed differential effects on GTPase activity and sedimentation characteristics of Dr-FtsZ and Ec-FtsZ. For instance, Dr-FtsA stimulated GTPase activity of Dr-FtsZ while GTPase activity of Ec-FtsZ was reduced in the presence of Dr-FtsA. Stimulation of GTPase activity of Dr-FtsZ by Dr-FtsA resulted in depolymerization of Dr-FtsZ. Dr-FtsA effects on GTPase activity and polymerization/depolymerisation characteristics of Dr-FtsZ did not change significantly in the presence of ATP. Recombinant E. coli expressing Dr-FtsA showed cell division inhibition in spite of in trans expression of Dr-FtsZ in these cells. These results suggested that Dr-FtsA, although it lacks ATPase activity, is still functional and differentially affects Dr-FtsZ and Ec-FtsZ function in vitro.

  13. Laboratory-evolved mutants of an exogenous global regulator, IrrE from Deinococcus radiodurans, enhance stress tolerances of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Tingjian Chen

    Full Text Available BACKGROUND: The tolerance of cells toward different stresses is very important for industrial strains of microbes, but difficult to improve by the manipulation of single genes. Traditional methods for enhancing cellular tolerances are inefficient and time-consuming. Recently, approaches employing global transcriptional or translational engineering methods have been increasingly explored. We found that an exogenous global regulator, irrE from an extremely radiation-resistant bacterium, Deinococcus radiodurans, has the potential to act as a global regulator in Escherichia coli, and that laboratory-evolution might be applied to alter this regulator to elicit different phenotypes for E. coli. METHODOLOGY/PRINCIPAL FINDINGS: To extend the methodology for strain improvement and to obtain higher tolerances toward different stresses, we here describe an approach of engineering irrE gene in E. coli. An irrE library was constructed by randomly mutating the gene, and this library was then selected for tolerance to ethanol, butanol and acetate stresses. Several mutants showing significant tolerances were obtained and characterized. The tolerances of E. coli cells containing these mutants were enhanced 2 to 50-fold, based on cell growth tests using different concentrations of alcohols or acetate, and enhanced 10 to 100-fold based on ethanol or butanol shock experiments. Intracellular reactive oxygen species (ROS assays showed that intracellular ROS levels were sharply reduced for cells containing the irrE mutants. Sequence analysis of the mutants revealed that the mutations distribute cross all three domains of the protein. CONCLUSIONS: To our knowledge, this is the first time that an exogenous global regulator has been artificially evolved to suit its new host. The successes suggest the possibility of improving tolerances of industrial strains by introducing and engineering exogenous global regulators, such as those from extremophiles. This new approach can

  14. Complete genome sequence of the orange-red pigmented, radioresistant Deinococcus proteolyticus type strain (MRP(T)).

    Science.gov (United States)

    Copeland, Alex; Zeytun, Ahmet; Yassawong, Montri; Nolan, Matt; Lucas, Susan; Hammon, Nancy; Deshpande, Shweta; Cheng, Jan-Fang; Han, Cliff; Tapia, Roxanne; Goodwin, Lynne A; Pitluck, Sam; Mavromatis, Konstantinos; Liolios, Konstantinos; Pagani, Ioanna; Ivanova, Natalia; Mikhailova, Natalia; Pati, Amrita; Chen, Amy; Palaniappan, Krishna; Land, Miriam; Hauser, Loren; Jeffries, Cynthia D; Brambilla, Evelyne-Marie; Rohde, Manfred; Sikorski, Johannes; Pukall, Rüdiger; Göker, Markus; Detter, John C; Woyke, Tanja; Bristow, James; Eisen, Jonathan A; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter; Lapidus, Alla

    2012-05-25

    Deinococcus proteolyticus (ex Kobatake et al. 1973) Brook and Murray 1981 is one of currently 47 species in the genus Deinococcus within the family Deinococcaceae. Strain MRP(T) was isolated from feces of Lama glama and possesses extreme radiation resistance, a trait is shares with various other species of the genus Deinococcus, with D. proteolyticus being resistant up to 1.5 Mrad of gamma radiation. Strain MRP(T) is of further interest for its carotenoid pigment. The genome presented here is only the fifth completed genome sequence of a member of the genus Deinococcus (and the forth type strain) to be published, and will hopefully contribute to a better understanding of how members of this genus adapted to high gamma- or UV ionizing-radiation. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 2,886,836 bp long genome with its four large plasmids of lengths 97 kbp, 132 kbp, 196 kbp and 315 kbp harbors 2,741 protein-coding and 58 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  15. Synthesis of branched polyglucans by the tandem action of potato phosphorylase and Deinococcus geothermalis glycogen branching enzyme

    NARCIS (Netherlands)

    van der Vlist, Jeroen; Reixach, Marta Palomo; van der Maarel, Marc; Dijkhuizen, Lubbert; Schouten, Arend Jan; Loos, Katja

    2008-01-01

    An enzymatic tandem reaction is described in which the enzymes phosphorylase and Deinococcus geothermalis glycogen branching enzyme (Dg GBE) catalyze the synthesis of branched polyglucans from glucose-1-phosphate (G-1-P). Phosphorylase consumes G-1-P and polymerizes linear amylose while DR GBE

  16. Identification and characterization of the geranylgeranyl diphosphate synthase in Deinococcus radiodurans.

    Science.gov (United States)

    Liu, C; Sun, Z; Shen, S; Lin, L; Li, T; Tian, B; Hua, Y

    2014-03-01

    Deinococcus radiodurans strain R1 utilizes multiple antioxidants including a unique carotenoid, deinoxanthin, to fight again oxidative stress. Most of the enzymes involved in the deinoxanthin biosynthetic pathway have been identified. However, the enzyme catalysing the synthesis of geranylgeranyl diphosphate (GGPP), which is a precursor of carotenoid biosynthesis, has yet to be identified. Two putative isoprenyl diphosphate synthases (IPPS) homologues (DR1395 and DR932) were screened out by analysis of conserved amino acid regions, and their biochemical functions were investigated. Gene mutation, gene expression in Escherichia coli and analysis of carotenoid products were used to investigate the functions of these candidates. The results suggested that DR1395 encodes the protein for GGPP synthesis. Site-directed mutant analysis indicated that the amino acid composition of and around the first aspartate-rich motif is vital for GGPP synthase function. Deinococcus radiodurans strain R1 produces a unique carotenoid product, deinoxanthin, as an antioxidant. In this study, DR1395 was identified as the gene encoding geranylgeranyl diphosphate synthase (GGPPS) for entrance to deinoxanthin biosynthesis in D. radiodurans. Moreover, site-directed mutagenesis studies on DR1395 identified the effect of amino acid composition of the aspartate-rich motif on the production of this carotenoid. This study demonstrated the entrance step in the deinoxanthin biosynthetic pathway. These results can be useful in genetic engineering strategies for deinoxanthin production including enhancement of GGPPS gene expression in D. radiodurans. © 2013 The Society for Applied Microbiology.

  17. Knockout of pprM Decreases Resistance to Desiccation and Oxidation in Deinococcus radiodurans.

    Science.gov (United States)

    Zeng, Yang; Ma, Yun; Xiao, Fangzhu; Wang, Wuzhou; He, Shuya

    2017-09-01

    Deinococcus radiodurans has attracted a great interest in the past decades due to its extraordinary resistance to ionizing radiation and highly efficient DNA repair system. Recent studies indicated that pprM is a putative pleiotropic gene in D. radiodurans and plays an important role in radioresistance and antioxidation, but its underlying mechanisms are poorly elucidated. In this study, pprM mutation was generated to investigate resistance to desiccation and oxidative stress. The result showed that the survival of pprM mutant under desiccation was markedly retarded compared to the wild strain from day 7-28. Furthermore, knockout of pprM increases the intercellular accumulation of ROS and the sensibility to H2O2 stress in the bacterial growth inhibition assay. The absorbance spectrum experiment for detecting the carotenoid showed that deinoxanthin, a carotenoid that peculiarly exists in Deinococcus, was reduced in the pprM mutant in the pprM mutant. Quantitative real time PCR showed decreased expression of three genes viz. CrtI (DR0861, 50%),CrtB (DR0862, 40%) and CrtO (DR0093, 50%), which are involved in deinoxanthin synthesis, and of Dps (DNA protection during starving) gene (DRB0092) relevant to ion combining and DNA protection in cells. Our results suggest that pprM may affect antioxidative ability of D. radiodurans by regulating the synthesis of deinoxanthin and the concentration of metal ions. This may provide new clues for the treatment of antioxidants.

  18. [Seroepidemiological study of malaria in the Algerian Sahara].

    Science.gov (United States)

    Benzerroug, E H; Janssens, P G; Ambroise-Thomas, P

    1991-01-01

    On the basis of geoclimatic characteristics, the Saharan region of Algeria (area, 2 million km2) is made up of several subregions; analysis of the historical data on malaria in this region seems to show that the epidemiological situation is closely linked to climatic and hydrographic conditions. A longitudinal sero-epidemiological study was conducted in this vast region from September 1983 to April 1985. The general findings do not appear to support the existence of active foci of transmission, but analysis of the data for certain oases and localities leads to a quite different assessment of the epidemiological situation. At Ouargla, for example, the serological results obtained by indirect immunofluorescence show prevalence of under 5% in the four successive surveys, whereas in Heïha oasis over 50% of subjects over 30 years of age were found to be seropositive. The results of the longitudinal seroepidemiological surveys conducted in a number of localities and oases in the Saharan region reflect the diversity of epidemiological settings and provide evidence that there is low-level malaria transmission in some oases such as Heïha, Yakou, Ihérir and probably in In-Salah. These surveys confirm that malaria transmission has been halted in the former foci such as Ouargla and Timimoune. Finally, the longitudinal sero-epidemiological study shows there are movements of potential parasite carriers from countries south of the Sahara and therefore that oases associated with trans-Saharan trade are vulnerable.

  19. Biochemical and Functional Characterization of the NurA-HerA Complex from Deinococcus radiodurans.

    Science.gov (United States)

    Cheng, Kaiying; Chen, Xuanyi; Xu, Guangzhi; Wang, Liangyan; Xu, Hong; Yang, Su; Zhao, Ye; Hua, Yuejin

    2015-06-15

    In archaea, the NurA nuclease and HerA ATPase/helicase, together with the Mre11-Rad50 complex, function in 3' single-stranded DNA (ssDNA) end processing during homologous recombination (HR). However, bacterial homologs of NurA and HerA have not been characterized. From Deinococcus radiodurans, we identified the manganese-dependent 5'-to-3' ssDNA/double-stranded DNA (dsDNA) exonuclease/endonuclease NurA (DrNurA) and the ATPase HerA (DrHerA). These two proteins stimulated each other's activity through direct protein-protein interactions. The N-terminal HAS domain of DrHerA was the key domain for this interaction. Several critical residues of DrNurA and DrHerA were verified by site-directed mutational analysis. Temperature-dependent activity assays confirmed that the two proteins had mesophilic features, with optimum activity temperatures 10 °C to 15 °C higher than their optimum growth temperatures. Knocking out either nurA or herA affected cell proliferation by shortening the growth phase, especially for growth at a high temperature (37 °C). In addition, both mutant strains displayed almost 10-fold-reduced intermolecular recombination efficiency, indicating that DrNurA and DrHerA might be involved in homologous recombination in vivo. However, single- and double-gene deletions did not show significantly decreased radioresistance. Our results confirmed that the biochemical activities of bacterial NurA and HerA proteins were conserved with archaea. Our phenotypical results suggested that these proteins might have different functions in bacteria. Deinococcus radiodurans NurA (DrNurA) was identified as a manganese-dependent 5'-to-3' ssDNA/dsDNA exonuclease/endonuclease, and Deinococcus radiodurans HerA (DrHerA) was identified as an ATPase. Physical interactions between DrNurA and DrHerA explained mutual stimulation of their activities. The N-terminal HAS domain on DrHerA was identified as the interaction domain. Several essential functional sites on DrNurA and Dr

  20. LOW {sup 60}FE ABUNDANCE IN SEMARKONA AND SAHARA 99555

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Haolan; Dauphas, Nicolas, E-mail: haolantang@ucla.edu [Origins Lab, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago IL 60637 (United States)

    2015-03-20

    Iron-60 (t{sub 1/2} = 2.62 Myr) is a short-lived nuclide that can help constrain the astrophysical context of Solar System formation and date early Solar System events. A high abundance of {sup 60}Fe({sup 60}Fe/{sup 56}Fe ≈ 4 × 10{sup −7}) was reported by in situ techniques in some chondrules from the LL3.00 Semarkona meteorite, which was taken as evidence that a supernova exploded in the vicinity of the birthplace of the Sun. However, our previous multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) measurements of a wide range of meteoritic materials, including chondrules, showed that {sup 60}Fe was present in the early Solar System at a much lower level ({sup 60}Fe/{sup 56}Fe ≈ 10{sup −8}). The reason for the discrepancy is unknown but only two Semarkona chondrules were measured by MC-ICPMS and these had Fe/Ni ratios below ∼2× chondritic. Here, we show that the initial {sup 60}Fe/{sup 56}Fe ratio in Semarkona chondrules with Fe/Ni ratios up to ∼24× chondritic is (5.39 ± 3.27) × 10{sup −9}. We also establish the initial {sup 60}Fe/{sup 56}Fe ratio at the time of crystallization of the Sahara 99555 angrite, a chronological anchor, to be (1.97 ± 0.77) × 10{sup −9}. These results demonstrate that the initial abundance of {sup 60}Fe at Solar System birth was low, corresponding to an initial {sup 60}Fe/{sup 56}Fe ratio of (1.01 ± 0.27) × 10{sup −8}.

  1. Engineering of Deinococcus radiodurans R1 for Bioprecipitation of Uranium from Dilute Nuclear Waste▿

    Science.gov (United States)

    Appukuttan, Deepti; Rao, Amara Sambasiva; Apte, Shree Kumar

    2006-01-01

    Genetic engineering of radiation-resistant organisms to recover radionuclides/heavy metals from radioactive wastes is an attractive proposition. We have constructed a Deinococcus radiodurans strain harboring phoN, a gene encoding a nonspecific acid phosphatase, obtained from a local isolate of Salmonella enterica serovar Typhi. The recombinant strain expressed an ∼27-kDa active PhoN protein and efficiently precipitated over 90% of the uranium from a 0.8 mM uranyl nitrate solution in 6 h. The engineered strain retained uranium bioprecipitation ability even after exposure to 6 kGy of 60Co gamma rays. The PhoN-expressing D. radiodurans offers an effective and eco-friendly in situ approach to biorecovery of uranium from dilute nuclear waste. PMID:17056698

  2. Solution conformation of the response regulator proteins from Deinococcus radiodurans studied by SAXS

    Science.gov (United States)

    Li, Li-Qin; Liu, Ying; Liu, Peng; Dong, Yu-Hui

    2011-10-01

    In this paper the solution conformation of the response regulator proteins from Deinococcus radiodurans was studied by small-angle X-ray scattering (SAXS). The SAXS curves of Dr-rrA in solutions were obtained at Beamline 1W2A of Beijing Synchrotron Radiation Facility (BSRF). Two possible conformations of the response regulator proteins, compact and incompact conformations, have been represented by the known crystallographic structures. And theoretical solution scattering curves of the two possible conformations were calculated and fitted to the experimental scattering curve of Dr-rrA, respectively. The result indicates that the solution conformation of the response regulator proteins is inclined to the compact one, which is in agreement with the result of biochemical experiments.

  3. Dose Effects of Ion Beam Exposure on Deinococcus Radiodurans: Survival and Dose Response

    Science.gov (United States)

    Song, Dao-jun; Wu, Li-fang; Wu, Li-jun; Yu, Zeng-liang

    2001-02-01

    To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.coli, as the control) for ultra-violet (UV), γ-rays radiation and ion beam exposure was investigated. The shoulder type of survival curves were found for both UV and γ-ray ionizing radiation, but the saddle type of survival curves were shown for H+, N+(20keV and 30keV) and Ar+ beam exposure. This dose effect of the survival initially decreased with the increase in dose and then increased in the high dose range and finally decreased again in the higher dose range. Our experimental results suggest that D. radiodurans, which is considerably radio-resistant to UV and x-ray and γ-ray ionizing radiation, do not resist ion beam exposure.

  4. DNA microarray fabrication of deinococcus radiodurans R1 for a global gene expression profiling

    Energy Technology Data Exchange (ETDEWEB)

    Joe, Min Ho; Lim, Sang Young; Jung, Sun Wook; Choi, Young Ji; Lee, Bo Young; Song, Bu Sub; Jung, Jin Woo; Kim, Dong Ho [Radiation Research Center for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of); Chae, Sung Hwa [Research Institute of GnC BIO Co. Ltd., Daejeon (Korea, Republic of)

    2008-05-15

    DNA microarray technology is an extraordinarily powerful technique, which has revolutionized the world of science and technology more profoundly than any other recent major advance. In this study, we fabricated a DNA microarray chip of Deinococcus radiodurans R1 to get the comprehensive information of this organism responding to diverse conditions. Among 3,187 open reading frames (ORFs), the PCR products representing 3,116 ORFs were obtained by using polymerase chain reactions (PCRs) with gene-specific primer sets. The PCR products were spotted in duplicate onto a slide and immobilized successfully. Hybridization experiment showed an enough sensitivity and reliability of the DNA chip to analyze global gene expression of D. radiodurans R1. Finally, a clone library of the PCR products was constructed for convenience in later use. The success rate of the library construction was about 95%, meaning that 3,031 ORFs were cloned into a vector.

  5. Characterization and role of a 2',3'-cyclic phosphodiesterase from Deinococcus radiodurans.

    Science.gov (United States)

    Han, Wanchun; Zhou, Congli; Cheng, Jiahui; Pan, Mingzhe; Hua, Yuejin; Zhao, Ye

    2017-08-01

    A 2',3'-cyclic phosphodiesterase gene (drCPDase) has been characterized from Deinococcus radiodurans and is involved in the robust resistance of this organism. Cells lacking 2',3'-cyclic phosphodiesterase gene (drCPDase) showed modest growth defects and displayed increased sensitivities to high doses of various DNA-damaging agents including ionizing radiation, mitomycin C, UV and H2O2. The transcriptional level of drCPDase increased after H2O2 treatment. Additional nucleotide monophosphate partially recovered the phenotype of drCPDase knockout cells. Complementation of E. coli with drCPDase resulted in enhanced H2O2 resistance. The 2',3'-cyclic phosphodiesterase (drCPDase) contributes to the extreme resistance of D. radiodurans and is presumably involved in damaged nucleotide detoxification.

  6. Crystal Structure of Deinococcus radiodurans RecQ Helicase Catalytic Core Domain: The Interdomain Flexibility

    Directory of Open Access Journals (Sweden)

    Sheng-Chia Chen

    2014-01-01

    Full Text Available RecQ DNA helicases are key enzymes in the maintenance of genome integrity, and they have functions in DNA replication, recombination, and repair. In contrast to most RecQs, RecQ from Deinococcus radiodurans (DrRecQ possesses an unusual domain architecture that is crucial for its remarkable ability to repair DNA. Here, we determined the crystal structures of the DrRecQ helicase catalytic core and its ADP-bound form, revealing interdomain flexibility in its first RecA-like and winged-helix (WH domains. Additionally, the WH domain of DrRecQ is positioned in a different orientation from that of the E. coli RecQ (EcRecQ. These results suggest that the orientation of the protein during DNA-binding is significantly different when comparing DrRecQ and EcRecQ.

  7. Insight into the Strong Antioxidant Activity of Deinoxanthin, a Unique Carotenoid in Deinococcus Radiodurans

    Directory of Open Access Journals (Sweden)

    Hong-Fang Ji

    2010-11-01

    Full Text Available Deinoxanthin (DX is a unique carotenoid synthesized by Deinococcus radiodurans, one of the most radioresistant organisms known. In comparison with other carotenoids, DX was proven to exhibit significantly stronger reactive oxygen species (ROS-scavenging activity, which plays an important role in the radioresistance of D. radiodurans. In this work, to gain deeper insights into the strong antioxidant activity of DX, the parameters characterizing ROS-scavenging potential were calculated by means of quantum chemical calculations. It was found that DX possesses lower lowest triplet excitation energy for its unique structure than other carotenoids, such as β-carotene and zeaxanthin, which endows DX strong potential in the energy transfer-based ROS‑scavenging process. Moreover, the H-atom donating potential of DX is similar to zeaxanthin according to the theoretical homolytic O-H bond dissociation enthalpy. Thus, the large number of conjugated double bonds should be crucial for its strong antioxidant activity.

  8. African humid periods triggered the reactivation of a large river system in Western Sahara.

    Science.gov (United States)

    Skonieczny, C; Paillou, P; Bory, A; Bayon, G; Biscara, L; Crosta, X; Eynaud, F; Malaizé, B; Revel, M; Aleman, N; Barusseau, J-P; Vernet, R; Lopez, S; Grousset, F

    2015-11-10

    The Sahara experienced several humid episodes during the late Quaternary, associated with the development of vast fluvial networks and enhanced freshwater delivery to the surrounding ocean margins. In particular, marine sediment records off Western Sahara indicate deposition of river-borne material at those times, implying sustained fluvial discharges along the West African margin. Today, however, no major river exists in this area; therefore, the origin of these sediments remains unclear. Here, using orbital radar satellite imagery, we present geomorphological data that reveal the existence of a large buried paleodrainage network on the Mauritanian coast. On the basis of evidence from the literature, we propose that reactivation of this major paleoriver during past humid periods contributed to the delivery of sediments to the Tropical Atlantic margin. This finding provides new insights for the interpretation of terrigenous sediment records off Western Africa, with important implications for our understanding of the paleohydrological history of the Sahara.

  9. Monique VÉRITÉ, Henri Lhote – Une aventure scientifique au Sahara

    OpenAIRE

    Bruno LECOQUIERRE

    2015-01-01

    Auteur déjà en 1992 d’Odette du Puigaudeau : une bretonne au Sahara, Monique Vérité vient de livrer une nouvelle biographie passionnante, sur une personnalité saharienne haute en couleur, célèbre en France et au Sahara après-guerre et qui est aujourd’hui un peu oubliée : Henri Lhote (1903-1991). Henri Lhote peut être considéré comme l’un des plus grands explorateurs du Sahara au XXe siècle, aux côtés de Conrad Kilian et de Théodore Monod. Le parallèle avec ce dernier est assez fascinant car c...

  10. A NEW SPECIES OF CYRTOSPIRIFER (BRACHIOPODA FROM THE MIDDLE DEVONIAN OF THE WESTERN SAHARA (NORTHWESTERN AFRICA

    Directory of Open Access Journals (Sweden)

    MENA SCHEMM-GREGORY

    2011-03-01

    Full Text Available A new species of Cyrtospirifer is described from the Middle to Upper Givetian of the Western Sahara (Northwest Africa. Cyrtospirifer tindoufensis new species differs in its smaller number and coarser medial and flank plications and equibiconvex shell profile from the other Givetian species of Cyrtospirifer that all occur in Europe and to which the new species probably gives rise. The new implications of the proposed phylogeny of the earliest cyrtospiriferids and their origin from the Western Sahara are discussed. The palaeogeographic distribution of the cyrtospiriferids during the Givetian and Frasnian is shown and its migration ways are described considering the global transgression and regression cycles. 

  11. The blurred boundaries of political violence in the Sahel-Sahara

    DEFF Research Database (Denmark)

    Walther, Olivier

    2017-01-01

    The Sahel and the Sahara are faced with exceptional political instability involving a combination of rebellions, jihadist insurgencies, coups d’état, protest movements and illegal trafficking. Analysis of the outbreaks of violence reveals that the region is not just the victim of an escalation...... of wars and conflicts that marked the 20th century. The Sahel-Sahara has also become the setting of a globalised security environment, in which boundaries between what is local and global, domestic and international, military and civilian, politics and identity are blurred....

  12. Ethnopharmacological survey and phytochemical screening of some medicinal Asteraceae from Algerian Sahara

    Directory of Open Access Journals (Sweden)

    A. CHERITI

    2013-06-01

    Full Text Available A first report of Asteraceae species census of the Algerian folk medicine, currently used in Sahara for the treatment of illenes is presented. 11 Asteraceae species namely: Anvillea radiata Coss, Artemisia herba-alba, Brocchia cinerea, Bubonium graveolens, Cotula anthemoides, Echinops spinosus, Launaea arborescens, Launaea nudicaulis, Launaea resedifolia, Scorzonera undulata and Warionia saharae were selected based on the survey through interviews with local inhabitant, herbalist in the Souk and old women according to our previous works. Ethnopharmacolgical potential and chemical constituents of this species are described.

  13. Ethnopharmacological survey and phytochemical screening of some medicinal Asteraceae from Algerian Sahara

    Directory of Open Access Journals (Sweden)

    A CHERITI

    2013-06-01

    Full Text Available A first report of Asteracea species census of the Algerian folk medicine, currently used in Sahara for the treatment of illenes is presented. 11 Asteraceae species namely: Anvillea radiata coss, Artemisia herba-alba, Brocchia cinerea, Bubonium graveolens, Cotula anthemoides, Echinops spinosus, Launaea arborescens, Launaea nudicaulis, Launaea resedifolia, Scorzonera undulata and Warionia saharae were selected based on the survey through interviews with local inhabitant, herbalist in the Souk and old women according to our previous works. Ethnopharmacolgical potential and chemical constituents of this species are described.

  14. Characterizing the Catalytic Potential of Deinococcus, Arthrobacter and other Robust Bacteria in Contaminated Subsurface Environments of the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Daly, Michael J.

    2006-05-01

    Ionizing Radiation (IR) Resistance in Bacteria. Until recently, there have been no clear physiologic predictors of a cell's ability to recover from ionizing radiation (IR) and other DOE-relevant oxidative stress conditions. In general, the most resistant bacteria have been Gram-positive (e.g., Deinococcus, Arthrobacter, Lactobacillus & Enterococcus spp.) and the most sensitive have been Gram-negative (e.g., Pseudomonas, Shewanella & Neisseria spp.). However, there are several reported exceptions to this paradigm, the Gram-negative cyanobacterium Chroococcidiopsis is extremely resistant to IR, whereas the Gram-positive Micrococcus luteus is sensitive. We have identified biomolecular signatures for radiation sensitivity and resistance which are independent of phylogeny, where very high and very low intracellular Mn/Fe concentration ratios correlated with very high and very low resistances, respectively; and restricting Mn(II) in the famously resistant Deinococcus radiodurans sensitized this eubacterium to IR.

  15. Characterizing the Catalytic Potential of Deinococcus, Arthrobacter and other Robust Bacteria in Contaminated Subsurface Environments of the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Fredrickson, Jim K.; Daly, Michael J.

    2006-06-01

    Until recently, there have been no clear physiologic predictors of a cell's ability to recover from ionizing radiation (IR), desiccation, and other DOE-relevant oxidative stress conditions. In general, the most resistant bacteria have been Gram-positive (e.g., Deinococcus, Arthrobacter, Lactobacillus & Enterococcus spp.) and the most sensitive have been Gram-negative (e.g., Pseudomonas, Shewanella & Neisseria spp.). However, there are several reported exceptions to this paradigm, the Gram-negative cyanobacterium Chroococcidiopsis is extremely resistant to IR, whereas the Gram-positive Micrococcus luteus is sensitive. We have identified biomolecular signatures for radiation sensitivity and resistance which are independent of phylogeny, where very high and very low intracellular Mn/Fe concentration ratios correlated with very high and very low resistances, respectively; and restricting Mn(II) in the famously resistant Deinococcus radiodurans sensitized this eubacterium to IR (http://cfyn.ifas.ufl.edu/radiation.pdf).

  16. Deinococcus radiodurans DR1088 is a novel RecF-interacting protein that stimulates single-stranded DNA annealing.

    Science.gov (United States)

    Cheng, Kaiying; Xu, Guangzhi; Xu, Hong; Zhao, Ye; Hua, Yuejin

    2017-11-01

    RecF, together with the recombination mediators RecO and RecR, is required in the RecFOR homologous recombination repair pathway in bacteria. In this study, a recF-dr1088 operon, which is highly conserved in the Deinococcus-Thermus phylum, was identified in Deinococcus radiodurans. Interaction between DRRecF and DR1088 was confirmed by yeast two-hybrid and pull-down assays. DR1088 exhibited some RecO-like biochemical properties including single/double-stranded DNA binding activity, ssDNA binding protein (SSB) replacement ability and ssDNA (with or without SSB) annealing activity. However, unlike other recombination proteins, dr1088 is essential for cell viability. These results indicate that DR1088 might play a role in DNA replication and DNA repair processes. © 2017 John Wiley & Sons Ltd.

  17. Effects of Low-Temperature Plasma-Sterilization on Mars Analog Soil Samples Mixed with Deinococcus radiodurans

    OpenAIRE

    Janosch Schirmack; Marcel Fiebrandt; Katharina Stapelmann; Dirk Schulze-Makuch

    2016-01-01

    We used Ar plasma-sterilization at a temperature below 80 ?C to examine its effects on the viability of microorganisms when intermixed with tested soil. Due to a relatively low temperature, this method is not thought to affect the properties of a soil, particularly its organic component, to a significant degree. The method has previously been shown to work well on spacecraft parts. The selected microorganism for this test was Deinococcus radiodurans R1, which is known for its remarkable resis...

  18. Quality in primary health care services in sub-Sahara Africa: right or ...

    African Journals Online (AJOL)

    The Primary Health Care (PHC) system has been the foundation for the operation of the health system in most of Sub-Sahara Africa following the Alma Ata Declaration in 1978. Quality of care is an important determinant of health services utilization, and is a health outcome of public health importance. It is known that the ...

  19. Green Sahara impact on mid-latitudes during mid-Holocene

    Science.gov (United States)

    Gaetani, Marco; Messori, Gabriele; Pausata, Francesco S. R.; Zhang, Qiong

    2017-04-01

    In the mid-Holocene (6 kyr before present), North Africa was characterised by a vegetated Sahara and a stronger summer monsoon, resulting in a wetter climate. These conditions, induced by the different Earth's orbital parameters, and maintained by the precipitation-vegetation feedback, were associated with a substantial change of the regional atmospheric dynamics, with influences extending across the global Tropics and beyond. In this study, we explore the mid-latitude response to the vegetated Sahara in the mid-Holocene. We use the EC-Earth climate model to simulate the North African environment during mid-Holocene, i.e. extensive vegetation over the Sahara, and a consequent reduced dust emission. Vegetation and dust reduction are prescribed both in combination and in isolation, to determine the specific responses to the individual forcings. A significant response at mid-latitudes is simulated during boreal summer, when the precipitation-vegetation feedback is maximum in the Sahara. Results show increased precipitation over Mediterranean and Middle East, and warm anomalies across western Europe. This response is associated with the modification of the atmospheric circulation in the Euro-Atlantic sector. Specifically, the intensification of the subtropical jetstream favours precipitation across the Middle East, while a positive anomaly in the North Atlantic Oscillation leads the warming further west. These results suggest important implications for the understanding of future climate scenarios in the region, since a number of simulations project wetter conditions in North Africa.

  20. Hibiscus plant named `Sahara Sunset` U.S. Plant Patent 21,765

    Science.gov (United States)

    'Sahara Sunset' is a new and distinct cultivar of Hibiscus, botanically known as Hibiscus acetosella. The new Hibiscus was originated in Poplarville, Miss. and is a product of a mutation induction program. The parent of the present new cultivar is an unknown Hibiscus acetosella Wels. Ex Hiern seedli...

  1. Sud du Sahara | Page 59 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    flexible layoutflexible layoutflexible layoutflexible layoutflexible layoutflexible layoutflexible layoutflexible layoutflexible layout. Sud du Sahara. According to the International Land Coalition, between 2000 and 2010, foreign actors and country elites acquired an estimated 83 million hectares through large-scale land ...

  2. Alternate non-stop migration strategies of pied flycatchers to cross the Sahara desert

    NARCIS (Netherlands)

    Ouwehand, Janne; Both, Christiaan

    Each year more than two billion songbirds cross the Sahara, but how they perform this formidable task is largely unknown. Using geolocation tracks from 27 pied flycatchers, a nocturnally migrating passerine, we show that most birds made diurnal flights in both autumn and spring. These diurnal

  3. Le Sahara marocain : désenclavement et développement durable

    Directory of Open Access Journals (Sweden)

    EL MAHJOUB CHMOURK

    2012-04-01

    Full Text Available The Moroccan Sahara: opening-up and sustainable development. The enclosing of the Moroccan Sahara results from the inversion and old situation. Indeed, during a very long time, the area was a way of passage, a platform in the south of Morocco. In testify the Tran-Saharan commercial routes, which were the main transportation routes back in time, like the goal of integration of the area in the country and compared to western Africa. It is with the economic crisis, and even a political crisis causing a fold on itself of this area until 1975.Since Sahara belongs to Morocco, it still profits a considerable public effort to carry out its opening-up and its economic insertion within the country. Massive investments carried out by the State give to the area the structuring which it missed. Which are the aspects of the Sahara development? Which role played the State in this development? The intervention of the State contributes to bring effective solutions to the problem of the opening-up of this surrounding space?

  4. Reconstruction of exposure histories of meteorites from Antarctica and the Sahara

    Energy Technology Data Exchange (ETDEWEB)

    Neupert, U.; Neumann, S.; Leya, I.; Michel, R. [Hannover Univ. (Germany). Zentraleinrichtung fuer Strahlenschutz (ZfS); Kubik, P.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Bonani, G.; Hajdas, I.; Suter, M. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    {sup 10}Be, {sup 14}C, and {sup 26}Al were analyzed in H-, L-, and LL-chondrites from the Acfer region in the Algerian Sahara and from the Allan Hills/Antarctica. Exposure histories and terrestrial ages could be determined. (author) 3 figs., 2 refs.

  5. Equity in access to ARV drugs in Malawi | Ntata | SAHARA-J ...

    African Journals Online (AJOL)

    SAHARA-J: Journal of Social Aspects of HIV/AIDS. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 4, No 1 (2007) >. Log in or Register to get access to full text downloads.

  6. SAHARA-J: Journal of Social Aspects of HIV/AIDS: Editorial Policies

    African Journals Online (AJOL)

    SAHARA Journal Mission Statement The journal publishes contributions in English and French from all fields of social aspects of HIV/AIDS (care, support, ... culture, faith-based approaches, evidence-based intervention, health communication, structural and environmental intervention, financing, policy, media, etc).

  7. Lakeside Cemeteries in the Sahara: 5000 Years of Holocene Population and Environmental Change

    Science.gov (United States)

    Sereno, Paul C.; Garcea, Elena A. A.; Jousse, Hélène; Stojanowski, Christopher M.; Saliège, Jean-François; Maga, Abdoulaye; Ide, Oumarou A.; Knudson, Kelly J.; Mercuri, Anna Maria; Stafford, Thomas W.; Kaye, Thomas G.; Giraudi, Carlo; N'siala, Isabella Massamba; Cocca, Enzo; Moots, Hannah M.; Dutheil, Didier B.; Stivers, Jeffrey P.

    2008-01-01

    Background Approximately two hundred human burials were discovered on the edge of a paleolake in Niger that provide a uniquely preserved record of human occupation in the Sahara during the Holocene (∼8000 B.C.E. to the present). Called Gobero, this suite of closely spaced sites chronicles the rapid pace of biosocial change in the southern Sahara in response to severe climatic fluctuation. Methodology/Principal Findings Two main occupational phases are identified that correspond with humid intervals in the early and mid-Holocene, based on 78 direct AMS radiocarbon dates on human remains, fauna and artifacts, as well as 9 OSL dates on paleodune sand. The older occupants have craniofacial dimensions that demonstrate similarities with mid-Holocene occupants of the southern Sahara and Late Pleistocene to early Holocene inhabitants of the Maghreb. Their hyperflexed burials compose the earliest cemetery in the Sahara dating to ∼7500 B.C.E. These early occupants abandon the area under arid conditions and, when humid conditions return ∼4600 B.C.E., are replaced by a more gracile people with elaborated grave goods including animal bone and ivory ornaments. Conclusions/Significance The principal significance of Gobero lies in its extraordinary human, faunal, and archaeological record, from which we conclude the following: The early Holocene occupants at Gobero (7700–6200 B.C.E.) were largely sedentary hunter-fisher-gatherers with lakeside funerary sites that include the earliest recorded cemetery in the Sahara.Principal components analysis of craniometric variables closely allies the early Holocene occupants at Gobero with a skeletally robust, trans-Saharan assemblage of Late Pleistocene to mid-Holocene human populations from the Maghreb and southern Sahara.Gobero was abandoned during a period of severe aridification possibly as long as one millennium (6200–5200 B.C.E).More gracile humans arrived in the mid-Holocene (5200–2500 B.C.E.) employing a diversified

  8. Lakeside cemeteries in the Sahara: 5000 years of holocene population and environmental change.

    Directory of Open Access Journals (Sweden)

    Paul C Sereno

    Full Text Available BACKGROUND: Approximately two hundred human burials were discovered on the edge of a paleolake in Niger that provide a uniquely preserved record of human occupation in the Sahara during the Holocene ( approximately 8000 B.C.E. to the present. Called Gobero, this suite of closely spaced sites chronicles the rapid pace of biosocial change in the southern Sahara in response to severe climatic fluctuation. METHODOLOGY/PRINCIPAL FINDINGS: Two main occupational phases are identified that correspond with humid intervals in the early and mid-Holocene, based on 78 direct AMS radiocarbon dates on human remains, fauna and artifacts, as well as 9 OSL dates on paleodune sand. The older occupants have craniofacial dimensions that demonstrate similarities with mid-Holocene occupants of the southern Sahara and Late Pleistocene to early Holocene inhabitants of the Maghreb. Their hyperflexed burials compose the earliest cemetery in the Sahara dating to approximately 7500 B.C.E. These early occupants abandon the area under arid conditions and, when humid conditions return approximately 4600 B.C.E., are replaced by a more gracile people with elaborated grave goods including animal bone and ivory ornaments. CONCLUSIONS/SIGNIFICANCE: The principal significance of Gobero lies in its extraordinary human, faunal, and archaeological record, from which we conclude the following: The early Holocene occupants at Gobero (7700-6200 B.C.E. were largely sedentary hunter-fisher-gatherers with lakeside funerary sites that include the earliest recorded cemetery in the Sahara.Principal components analysis of craniometric variables closely allies the early Holocene occupants at Gobero with a skeletally robust, trans-Saharan assemblage of Late Pleistocene to mid-Holocene human populations from the Maghreb and southern Sahara.Gobero was abandoned during a period of severe aridification possibly as long as one millennium (6200-5200 B.C.E.More gracile humans arrived in the mid

  9. Unravelling biodiversity, evolution and threats to conservation in the Sahara-Sahel.

    Science.gov (United States)

    Brito, José C; Godinho, Raquel; Martínez-Freiría, Fernando; Pleguezuelos, Juan M; Rebelo, Hugo; Santos, Xavier; Vale, Cândida G; Velo-Antón, Guillermo; Boratyński, Zbyszek; Carvalho, Sílvia B; Ferreira, Sónia; Gonçalves, Duarte V; Silva, Teresa L; Tarroso, Pedro; Campos, João C; Leite, João V; Nogueira, Joana; Alvares, Francisco; Sillero, Neftalí; Sow, Andack S; Fahd, Soumia; Crochet, Pierre-André; Carranza, Salvador

    2014-02-01

    Deserts and arid regions are generally perceived as bare and rather homogeneous areas of low diversity. The Sahara is the largest warm desert in the world and together with the arid Sahel displays high topographical and climatic heterogeneity, and has experienced recent and strong climatic oscillations that have greatly shifted biodiversity distribution and community composition. The large size, remoteness and long-term political instability of the Sahara-Sahel, have limited knowledge on its biodiversity. However, over the last decade, there have been an increasing number of published scientific studies based on modern geomatic and molecular tools, and broad sampling of taxa of these regions. This review tracks trends in knowledge about biodiversity patterns, processes and threats across the Sahara-Sahel, and anticipates needs for biodiversity research and conservation. Recent studies are changing completely the perception of regional biodiversity patterns. Instead of relatively low species diversity with distribution covering most of the region, studies now suggest a high rate of endemism and larger number of species, with much narrower and fragmented ranges, frequently limited to micro-hotspots of biodiversity. Molecular-based studies are also unravelling cryptic diversity associated with mountains, which together with recent distribution atlases, allows identifying integrative biogeographic patterns in biodiversity distribution. Mapping of multivariate environmental variation (at 1 km × 1 km resolution) of the region illustrates main biogeographical features of the Sahara-Sahel and supports recently hypothesised dispersal corridors and refugia. Micro-scale water-features present mostly in mountains have been associated with local biodiversity hotspots. However, the distribution of available data on vertebrates highlights current knowledge gaps that still apply to a large proportion of the Sahara-Sahel. Current research is providing insights into key

  10. Functional and Structural Characterization of DR_0079 from Deinococcus radiodurans, a Novel Nudix Hydrolase with a Preference for Cytosine (Deoxy)ribonucleoside 5 -Di- and Triphophates

    Energy Technology Data Exchange (ETDEWEB)

    Buchko,G.; Litvinova, O.; Robinson, H.; Yakunin, A.; Kennedy, M.

    2008-01-01

    The genome of the extremely radiation resistant bacterium Deinococcus radiodurans encodes 21 Nudix hydrolases, of which only two have been characterized in detail. Here we report the activity and crystal structure for DR{_}0079, the first Nudix hydrolase observed to have a marked preference for cytosine ribonucleoside 5'-diphosphate (CDP) and cytosine ribonucleoside 5'-triphosphate (CTP). After CDP and CTP, the next most preferred substrates for DR{_}0079, with a relative activity of <50%, were the corresponding deoxyribose nucleotides, dCDP and dCTP. Hydrolase activity at the site of the phosphodiester bond was corroborated using 31P NMR spectroscopy to follow the phosphorus resonances for three substrates, CDP, IDP, and CTP, and their hydrolysis products, CMP + Pi, IMP + Pi, and CMP + PPi, respectively. Nucleophilic substitution at the {beta}-phosphorus of CDP and CTP was established, using 31P NMR spectroscopy, by the appearance of an upfield-shifted Pi resonance and line-broadened PPi resonance, respectively, when the hydrolysis was performed in 40% H218O-enriched water. The optimal activity for CDP was at pH 9.0-9.5 with the reaction requiring divalent metal cation (Mg2+ > Mn2+ > Co2+). The biochemical data are discussed with reference to the crystal structure for DR{_}0079 that was determined in the metal-free form at 1.9 Angstroms resolution. The protein contains nine {beta}-strands, three a-helices, and two 310-helices organized into three subdomains: an N-terminal {beta}-sheet, a central Nudix core, and a C-terminal helix-turn-helix motif. As observed for all known structures of Nudix hydrolases, the a-helix of the 'Nudix box' is one of two helices that sandwich a 'four-strand' mixed {beta}-sheet. To identify residues potentially involved in metal and substrate binding, NMR chemical shift mapping experiments were performed on 15N-labeled DR{_}0079 with the paramagnetic divalent cation Co2+ and the nonhydrolyzable substrate

  11. In Situ Determination of Manganese(II) Speciation in Deinococcus radiodurans by High Magnetic Field EPR

    Science.gov (United States)

    Tabares, Leandro C.; Un, Sun

    2013-01-01

    High magnetic field high frequency electron paramagnetic resonance techniques were used to measure in situ Mn(II) speciation in Deinococcus radiodurans, a radiation-resistant bacteria capable of accumulating high concentrations of Mn(II). It was possible to identify and quantify the evolution of Mn(II) species in intact cells at various stages of growth. Aside from water, 95-GHz high field electron nuclear double resonance showed that the Mn(II) ions are bound to histidines and phosphate groups, mostly from fructose-1,6-bisphosphate but also inorganic phosphates and nucleotides. During stationary growth phase, 285-GHz continuous wave EPR measurements showed that histidine is the most common ligand to Mn(II) and that significant amounts of cellular Mn(II) in D. radiodurans are bound to peptides and proteins. As much as 40% of the total Mn(II) was in manganese superoxide dismutase, and it is this protein and not smaller manganese complexes, as has been suggested recently, that is probably the primary defense against superoxide. PMID:23303180

  12. Irradiation-induced Deinococcus radiodurans genome fragmentation triggers transposition of a single resident insertion sequence.

    Directory of Open Access Journals (Sweden)

    Cécile Pasternak

    2010-01-01

    Full Text Available Stress-induced transposition is an attractive notion since it is potentially important in creating diversity to facilitate adaptation of the host to severe environmental conditions. One common major stress is radiation-induced DNA damage. Deinococcus radiodurans has an exceptional ability to withstand the lethal effects of DNA-damaging agents (ionizing radiation, UV light, and desiccation. High radiation levels result in genome fragmentation and reassembly in a process which generates significant amounts of single-stranded DNA. This capacity of D. radiodurans to withstand irradiation raises important questions concerning its response to radiation-induced mutagenic lesions. A recent study analyzed the mutational profile in the thyA gene following irradiation. The majority of thyA mutants resulted from transposition of one particular Insertion Sequence (IS, ISDra2, of the many different ISs in the D. radiodurans genome. ISDra2 is a member of a newly recognised class of ISs, the IS200/IS605 family of insertion sequences.

  13. Expression and mutational analysis of DinB-like protein DR0053 in Deinococcus radiodurans.

    Science.gov (United States)

    Appukuttan, Deepti; Seo, Ho Seong; Jeong, Sunwook; Im, Sunghun; Joe, Minho; Song, Dusup; Choi, Jungjoon; Lim, Sangyong

    2015-01-01

    In order to understand the mechanism governing radiation resistance in Deinococcus radiodurans, current efforts are aimed at identifying potential candidates from a large repertoire of unique Deinococcal genes and protein families. DR0053 belongs to the DinB/YfiT protein family, which is an over-represented protein family in D. radiodurans. We observed that dr0053 transcript levels were highly induced in response to gamma radiation (γ-radiation) and mitomycin C (MMC) exposure depending on PprI, RecA and the DrtR/S two-component signal transduction system. Protein profiles demonstrated that DR0053 is a highly induced protein in cultures exposed to 10 kGy γ-radiation. We were able to determine the transcriptional start site of dr0053, which was induced upon irradiation, and to assign the 133-bp promoter region of dr0053 as essential for radiation responsiveness through primer extension and promoter deletion analyses. A dr0053 mutant strain displayed sensitivity to γ-radiation and MMC exposure, but not hydrogen peroxide, suggesting that DR0053 helps cells recover from DNA damage. Bioinformatic analyses revealed that DR0053 is similar to the Bacillus subtilis protein YjoA, which is a substrate of bacterial protein-tyrosine kinases. Taken together, the DNA damage-inducible (din) gene dr0053 may be regulated at the transcriptional and post-translational levels.

  14. Characteristics of dr1790 disruptant and its functional analysis in Deinococcus radiodurans.

    Science.gov (United States)

    Cheng, Jianhui; Wang, Hu; Xu, Xin; Wang, Liangyan; Tian, Bing; Hua, Yuejin

    2015-06-01

    Deinococcus radiodurans (DR) is an extremophile that is well known for its resistance to radiation, oxidants and desiccation. The gene dr1790 of D. radiodurans was predicted to encode a yellow-related protein. The primary objective of the present study was to characterize the biological function of the DR1790 protein, which is a member of the ancient yellow/major royal jelly (MRJ) protein family, in prokaryotes. Fluorescence labeling demonstrated that the yellow-related protein encoded by dr1790 is a membrane protein. The deletion of the dr1790 gene decreased the cell growth rate and sensitivity to hydrogen peroxide and radiation and increased the membrane permeability of D. radiodurans. Transcript profiling by microarray and RT-PCR analyses of the dr1790 deletion mutant suggested that some genes that are involved in protein secretion and transport were strongly suppressed, while other genes that are involved in protein quality control, such as chaperones and proteases, were induced. In addition, the expression of genes with predicted functions that are involved in antioxidant systems, electron transport, and energy metabolism was significantly altered through the disruption of dr1790. Moreover, the results of proteomic analyses using 2-DE and MS also demonstrated that DR1790 contributed to D. radiodurans survival. Taken together, these results indicate that the DR1790 protein from the ancient yellow protein family plays a pleiotropic role in the survival of prokaryotic cells and contributes to the extraordinary resistance of D. radiodurans against oxidative and radiation stresses.

  15. Characteristics of dr1790 disruptant and its functional analysis in Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Jianhui Cheng

    2015-06-01

    Full Text Available Deinococcus radiodurans (DR is an extremophile that is well known for its resistance to radiation, oxidants and desiccation. The gene dr1790 of D. radiodurans was predicted to encode a yellow-related protein. The primary objective of the present study was to characterize the biological function of the DR1790 protein, which is a member of the ancient yellow/major royal jelly (MRJ protein family, in prokaryotes. Fluorescence labeling demonstrated that the yellow-related protein encoded by dr1790 is a membrane protein. The deletion of the dr1790 gene decreased the cell growth rate and sensitivity to hydrogen peroxide and radiation and increased the membrane permeability of D. radiodurans. Transcript profiling by microarray and RT-PCR analyses of the dr1790 deletion mutant suggested that some genes that are involved in protein secretion and transport were strongly suppressed, while other genes that are involved in protein quality control, such as chaperones and proteases, were induced. In addition, the expression of genes with predicted functions that are involved in antioxidant systems, electron transport, and energy metabolism was significantly altered through the disruption of dr1790. Moreover, the results of proteomic analyses using 2-DE and MS also demonstrated that DR1790 contributed to D. radiodurans survival. Taken together, these results indicate that the DR1790 protein from the ancient yellow protein family plays a pleiotropic role in the survival of prokaryotic cells and contributes to the extraordinary resistance of D. radiodurans against oxidative and radiation stresses.

  16. Expression and mutational analysis of DinB-like protein DR0053 in Deinococcus radiodurans.

    Directory of Open Access Journals (Sweden)

    Deepti Appukuttan

    Full Text Available In order to understand the mechanism governing radiation resistance in Deinococcus radiodurans, current efforts are aimed at identifying potential candidates from a large repertoire of unique Deinococcal genes and protein families. DR0053 belongs to the DinB/YfiT protein family, which is an over-represented protein family in D. radiodurans. We observed that dr0053 transcript levels were highly induced in response to gamma radiation (γ-radiation and mitomycin C (MMC exposure depending on PprI, RecA and the DrtR/S two-component signal transduction system. Protein profiles demonstrated that DR0053 is a highly induced protein in cultures exposed to 10 kGy γ-radiation. We were able to determine the transcriptional start site of dr0053, which was induced upon irradiation, and to assign the 133-bp promoter region of dr0053 as essential for radiation responsiveness through primer extension and promoter deletion analyses. A dr0053 mutant strain displayed sensitivity to γ-radiation and MMC exposure, but not hydrogen peroxide, suggesting that DR0053 helps cells recover from DNA damage. Bioinformatic analyses revealed that DR0053 is similar to the Bacillus subtilis protein YjoA, which is a substrate of bacterial protein-tyrosine kinases. Taken together, the DNA damage-inducible (din gene dr0053 may be regulated at the transcriptional and post-translational levels.

  17. Effects of FMN riboswitch on antioxidant activity in Deinococcus radiodurans under H₂O₂ stress.

    Science.gov (United States)

    Yang, Peng; Chen, Zhouwei; Shan, Zhan; Ding, Xianfeng; Liu, Lili; Guo, Jiangfeng

    2014-01-01

    The flavin mononucleotide (FMN) riboswitch is structured noncoding RNA domains that control gene expression by selectively binding FMN or sensing surrounding changes without protein factors, which are involved in the biosynthesis and transport of riboflavin and related compounds. We constructed the deletion mutant of FMN riboswitch to investigate its possible role in response to H₂O₂ stress in Deinococcus radiodurans. The results showed that the deletion of FMN riboswitch resulted in an obvious growth delay in D. radiodurans. Compared with the survival rate of 56% of D. radiodurans, only 40% of the mutant survived after treated with 50 mM of H₂O₂, indicating that deletion of FMN riboswitch obviously increased the susceptibility to H₂O₂. Compared with the wild type R1 strain of D. radiodurans, FMN riboswitch knockout cells accumulated a higher level of intracellular reactive oxygen species (ROS) while their total catalase activity reduced significantly. Results from quantitative real-time PCR analysis implies structural alterations of in response to H₂O₂ challenge. Our data suggest a critical role of FMN riboswitch in the oxidation tolerance system of D. radiodurans. Copyright © 2013 Elsevier GmbH. All rights reserved.

  18. Depletion of reduction potential and key energy generation metabolic enzymes underlies tellurite toxicity in Deinococcus radiodurans.

    Science.gov (United States)

    Anaganti, Narasimha; Basu, Bhakti; Gupta, Alka; Joseph, Daisy; Apte, Shree Kumar

    2015-01-01

    Oxidative stress resistant Deinococcus radiodurans surprisingly exhibited moderate sensitivity to tellurite induced oxidative stress (LD50 = 40 μM tellurite, 40 min exposure). The organism reduced 70% of 40 μM potassium tellurite within 5 h. Tellurite exposure significantly modulated cellular redox status. The level of ROS and protein carbonyl contents increased while the cellular reduction potential substantially decreased following tellurite exposure. Cellular thiols levels initially increased (within 30 min) of tellurite exposure but decreased at later time points. At proteome level, tellurite resistance proteins (TerB and TerD), tellurite reducing enzymes (pyruvate dehydrogense subunits E1 and E3), ROS detoxification enzymes (superoxide dismutase and thioredoxin reductase), and protein folding chaperones (DnaK, EF-Ts, and PPIase) displayed increased abundance in tellurite-stressed cells. However, remarkably decreased levels of key metabolic enzymes (aconitase, transketolase, 3-hydroxy acyl-CoA dehydrogenase, acyl-CoA dehydrogenase, electron transfer flavoprotein alpha, and beta) involved in carbon and energy metabolism were observed upon tellurite stress. The results demonstrate that depletion of reduction potential in intensive tellurite reduction with impaired energy metabolism lead to tellurite toxicity in D. radiodurans. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Harnessing a radiation inducible promoter of Deinococcus radiodurans for enhanced precipitation of uranium.

    Science.gov (United States)

    Misra, Chitra Seetharam; Mukhopadhyaya, Rita; Apte, Shree Kumar

    2014-11-10

    Bioremediation is an attractive option for the treatment of radioactive waste. We provide a proof of principle for augmentation of uranium bioprecipitation using the radiation inducible promoter, Pssb from Deinococcus radiodurans. Recombinant cells of D. radiodurans carrying acid phosphatase gene, phoN under the regulation of Pssb when exposed to 7 kGy gamma radiation at two different dose rates of 56.8 Gy/min and 4 Gy/min, showed 8-9 fold increase in acid phosphatase activity. Highest whole cell PhoN activity was obtained after 2h in post irradiation recovery following 8 kGy of high dose rate radiation. Such cells showed faster removal of high concentrations of uranium than recombinant cells expressing PhoN under a radiation non-inducible deinococcal promoter, PgroESL and could precipitate uranium even after continuous exposure to 0.6 Gy/min gamma radiation for 10 days. Radiation induced recombinant D. radiodurans cells when lyophilized retained high levels of PhoN activity and precipitated uranium efficiently. These results highlight the importance of using a suitable promoter for removal of radionuclides from solution. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Proteomic insights into the functional basis for the response regulator DrRRA of Deinococcus radiodurans.

    Science.gov (United States)

    Wang, Liangyan; Hu, Jing; Liu, Mengjia; Yang, Su; Zhao, Ye; Cheng, Kaiying; Xu, Guangzhi; Li, Mingfeng; Tian, Bing; Hua, Yuejin

    2016-05-01

    Purpose To investigate the function basis of the recently discovered response regulator, drRRA (DNA damage response regulator A) in Deinococcus radiodurans, we compared the proteomic profile of the radiation-sensitive drRRA mutant with that of wild-type strain under both non-stress and gamma radiation treatment. Materials and methods Total proteins of D. radiodurans cells were subjected to two-dimension electrophoresis. Protein spots in 2-Dimension gels were silver stained and scanned. Spots that changed significantly in expression levels were selected for mass spectrometry analysis. Seven genes encoding representative proteins were knocked out for stress resistance analysis. Results A total of 52 proteins displayed significant expression level changes at least 1.5-fold in the mutant relative to wild-type strain under non-stress conditions, with 31 repressed and 21 induced proteins, which might affect the cell response of D. radiodurans to gamma radiation. The proteins were distributed into functional groups including stress response, metabolism, and function unknown. Disruptions of several altered proteins including DRA0259 (Catalase E) and DR1538 (Osmotically inducible protein C), reduced the antioxidant activity of D. radiodurans. Conclusion Combined with our previous result of transcriptional profile, we further confirmed that inactivation of DrRRA affects the expression of various stress response systems.

  1. Identification and evaluation of the role of the manganese efflux protein in Deinococcus radiodurans

    Science.gov (United States)

    2010-01-01

    Background Deinococcus radiodurans accumulates high levels of manganese ions, and this is believed to be correlated with the radiation resistance ability of this microorganism. However, the maintenance of manganese ion homeostasis in D. radiodurans remains to be investigated. Results In this study, we identified the manganese efflux protein (MntE) in D. radiodurans. The null mutant of mntE was more sensitive than the wild-type strain to manganese ions, and the growth of the mntE mutant was delayed in manganese-supplemented media. Furthermore, there was a substantial increase in the in vivo concentration of manganese ions. Consistent with these characteristics, the mntE mutant was more resistant to H2O2, ultraviolet rays, and γ-radiation. The intracellular protein oxidation (carbonylation) level of the mutant strain was remarkably lower than that of the wild-type strain. Conclusions Our results indicated that dr1236 is indeed a mntE homologue and is indispensable for maintaining manganese homeostasis in D. radiodurans. The data also provide additional evidence for the involvement of intracellular manganese ions in the radiation resistance of D. radiodurans. PMID:21156049

  2. Hybrid Structure of a Dynamic Single-Chain Carboxylase from Deinococcus radiodurans.

    Science.gov (United States)

    Hagmann, Anna; Hunkeler, Moritz; Stuttfeld, Edward; Maier, Timm

    2016-08-02

    Biotin-dependent acyl-coenzyme A (CoA) carboxylases (aCCs) are involved in key steps of anabolic pathways and comprise three distinct functional units: biotin carboxylase (BC), biotin carboxyl carrier protein (BCCP), and carboxyl transferase (CT). YCC multienzymes are a poorly characterized family of prokaryotic aCCs of unidentified substrate specificity, which integrate all functional units into a single polypeptide chain. We employed a hybrid approach to study the dynamic structure of Deinococcus radiodurans (Dra) YCC: crystal structures of isolated domains reveal a hexameric CT core with extended substrate binding pocket and a dimeric BC domain. Negative-stain electron microscopy provides an approximation of the variable positioning of the BC dimers relative to the CT core. Small-angle X-ray scattering yields quantitative information on the ensemble of Dra YCC structures in solution. Comparison with other carrier protein-dependent multienzymes highlights a characteristic range of large-scale interdomain flexibility in this important class of biosynthetic enzymes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Deinococcus radiodurans pprI expression enhances the radioresistance of eukaryotes.

    Science.gov (United States)

    Wen, Ling; Yue, Ling; Shi, Yi; Ren, Lili; Chen, Tingting; Li, Na; Zhang, Shuyu; Yang, Wei; Yang, Zhanshan

    2016-03-29

    PprI accelerates radiation-induced DNA damage repair via regulating the expression of DNA repair genes and enhances antioxidative enzyme activity in Deinococcus radiodurans after radiation. The main aim of our study was to determine whether the expression of pprI gene could fulfil its DNA repair function in eukaryotes and enhance the radioresistance of eukaryotic organism or not. In this study, we constructed pEGFP-c1-pprI eukaryotic expression vector and established a human lung epithelial cell line BEAS-2B with stable integration of pprI gene. We found that pprIexpression enhanced radioresistance of BEAS-2B cells, decreased γ-H2AX foci formation and apoptosis in irradiated BEAS-2B cells and alleviated radiation induced G2/M arrest of BEAS-2B cells. Moreover, we transferred pEGFP-c1-pprI vector into muscle of BALB/c mice by in vivo electroporation and studied the protective effect of prokaryotic pprI gene in irradiated mice. We found that pprI expression alleviated acute radiation induced hematopoietic system, lung, small intestine and testis damage and increased survival rate of irradiated mice via regulating Rad51 expression in different organs. These findings suggest that prokaryotic pprI gene expression in mammalian cells could enhance radioresistance in vitro and in vivo.

  4. Characterization of a Deinococcus radiodurans MazF: A UACA-specific RNA endoribonuclease.

    Science.gov (United States)

    Miyamoto, Tatsuki; Ota, Yuri; Yokota, Akiko; Suyama, Tetsushi; Tsuneda, Satoshi; Noda, Naohiro

    2017-10-01

    Microbes are known to withstand environmental stresses by using chromosomal toxin-antitoxin systems. MazEF is one of the most extensively studied toxin-antitoxin systems. In stressful environments, MazF toxins modulate translation by cleaving single-stranded RNAs in a sequence-specific fashion. Previously, a chromosomal gene located at DR0417 in Deinococcus radiodurans was predicted to code for a MazF endoribonuclease (MazFDR0417 ); however, its function remains unclear. In the present study, we characterized the molecular function of MazFDR0417 . Analysis of MazFDR0417 -cleaved RNA sites using modified massively parallel sequencing revealed a unique 4-nt motif, UACA, as a potential cleavage pattern. The activity of MazFDR0417 was also assessed in a real-time fluorometric assay, which revealed that MazFDR0417 strictly recognizes the unique tetrad UACA. This sequence specificity may allow D. radiodurans to alter its translation profile and survive under stressful conditions. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  5. Crystal structure of a novel prolidase from Deinococcus radiodurans identifies new subfamily of bacterial prolidases.

    Science.gov (United States)

    Are, Venkata N; Jamdar, Sahayog N; Ghosh, Biplab; Goyal, Venuka Durani; Kumar, Ashwani; Neema, Sanchit; Gadre, Rekha; Makde, Ravindra D

    2017-12-01

    Xaa-Pro peptidases (XPP) are dinuclear peptidases of MEROPS M24B family that hydrolyze Xaa-Pro iminopeptide bond with a trans-proline at the second position of the peptide substrate. XPPs specific towards dipeptides are called prolidases while those that prefer longer oligopeptides are called aminopeptidases P. Though XPPs are strictly conserved in bacterial and archaeal species, the structural and sequence features that distinguish between prolidases and aminopeptidases P are not always clear. Here, we report 1.4 Å resolution crystal structure of a novel XPP from Deinococcus radiodurans (XPPdr). XPPdr forms a novel dimeric structure via unique dimer stabilization loops of N-terminal domains such that their C-terminal domains are placed far apart from each other. This novel dimerization is also the consequence of a different orientation of N-terminal domain in XPPdr monomer than those in other known prolidases. The enzymatic assays show that it is a prolidase with broad substrate specificity. Our structural, mutational, and molecular dynamics simulation analyses show that the conserved Arg46 of N-terminal domain is important for the dipeptide selectivity. Our BLAST search found XPPdr orthologs with conserved sequence motifs which correspond to unique structural features of XPPdr, thus identify a new subfamily of bacterial prolidases. © 2017 Wiley Periodicals, Inc.

  6. Identification and evaluation of the role of the manganese efflux protein in Deinococcus radiodurans.

    Science.gov (United States)

    Sun, Hongxing; Xu, Guangzhi; Zhan, Hongdan; Chen, Huan; Sun, Zongtao; Tian, Bing; Hua, Yuejin

    2010-12-14

    Deinococcus radiodurans accumulates high levels of manganese ions, and this is believed to be correlated with the radiation resistance ability of this microorganism. However, the maintenance of manganese ion homeostasis in D. radiodurans remains to be investigated. In this study, we identified the manganese efflux protein (MntE) in D. radiodurans. The null mutant of mntE was more sensitive than the wild-type strain to manganese ions, and the growth of the mntE mutant was delayed in manganese-supplemented media. Furthermore, there was a substantial increase in the in vivo concentration of manganese ions. Consistent with these characteristics, the mntE mutant was more resistant to H2O2, ultraviolet rays, and γ-radiation. The intracellular protein oxidation (carbonylation) level of the mutant strain was remarkably lower than that of the wild-type strain. Our results indicated that dr1236 is indeed a mntE homologue and is indispensable for maintaining manganese homeostasis in D. radiodurans. The data also provide additional evidence for the involvement of intracellular manganese ions in the radiation resistance of D. radiodurans.

  7. Metabolic engineering of deinococcus radiodurans based on computational analysis and functional genomics

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Jeremy, S.

    2005-02-02

    The objective of our work is to develop novel computational tools to analyze the Deinococcus radiodurans DNA repair pathways and the influence of the metabolic flux distribution on DNA repair. These tools will be applied to provide insights for metabolic engineering of strains capable of growing under nutrient poor conditions similar to those found in mixed contaminant sites of interest to the DOE. Over the entire grant period we accomplished all our specific aims and were also able to pursue new directions of research. Below, I will list the major accomplishments over the previous 3 years. (1) Performed Monte Carlo Simulations of RecA Mediated Pairing of Homologous DNA Molecules. (2) Developed a statistical approach to study the gene expression data from D. radiodurans. We have been studying the data from John Batista's. (3) Developed an expression profiling technology to generate very accurate and precise expression data. We followed up on results from John Batista's group using this approach. (4) Developed and put online a database for metabolic reconstructions. (5) We have developed and applied new Monte Carlo algorithms that are optimized for studying biological systems. (6) We developed a flux balance model for the D. radiodurans metabolic network

  8. Bioremediation of endocrine disruptor di-n-butyl phthalate ester by Deinococcus radiodurans and Pseudomonas stutzeri.

    Science.gov (United States)

    Liao, Chien-Sen; Chen, Lung-Chieh; Chen, Bing-Sheng; Lin, Sin-Hsien

    2010-01-01

    Di-n-butyl phthalate (DBP) is a group of phthalate esters (PAEs) that are widely used in cosmetics, perfumes, and plasticizers. Due to its high production and application figures, DBP is commonly found in wastewater, sewage sludge, and aquatic environments. It has been classified as suspected endocrine disruptors by most countries. In this study, we isolated two DBP degradable strains from activated sludge. The strains were identified with their 16S rRNA as Deinococcus radiodurans and Pseudomonas stutzeri. We constructed the optimal condition of DBP degradation by using different kinds of incubation factors such as temperature, initial pH, yeast extract and surfactants. The optimal conditions of DBP degradation for these two strains are: 30 degrees C, pH 7.5 and static culture. Besides, addition of 0.23 mM of Triton X-100 could enhance the DBP degradation for D. radiodurans. In the end, we amended these two strains into the origin activated sludge and analyzed the whole microbial community structure of mixed cultures by PCR-DGGE technique. The result showed that only D. radiodurans could survive in the activated sludge after 7d of incubation. Based on this work, we hope that these findings could provide some useful information for applying the bioremediation of DBP in our environment. Copyright 2009 Elsevier Ltd. All rights reserved.

  9. Roles of DNA repair and membrane integrity in heat resistance of Deinococcus radiodurans.

    Science.gov (United States)

    Bauermeister, Anja; Hahn, Claudia; Rettberg, Petra; Reitz, Günther; Moeller, Ralf

    2012-11-01

    To study the effects of heat shock on Deinococcus radiodurans and the role of DNA repair in high temperature resistance, different strains of D. radiodurans (wild type, recA, irrE, and pprA) were treated with temperatures ranging from 40 to 100 °C under wet and dry conditions. The mutant strains were more sensitive to wet heat of ≥60 °C and dry heat of ≥80 °C than the wild type. Both wild-type and DNA repair-deficient strains were much more resistant to high temperatures when exposed in the dried state as opposed to cells in suspension. Molecular staining techniques with the wild-type strain revealed that cells in the dried state were able to retain membrane integrity after drying and subsequent heat exposure, while heat-exposed cells in suspension showed significant loss of membrane integrity and respiration activity. The results suggest that the repair of DNA damage (e.g., DNA double-strand breaks by RecA and PprA) is essential after treatment with wet heat at temperatures >60 °C and dry heat >80 °C, and the ability of D. radiodurans to stabilize its plasma membrane during dehydration might represent one aspect in the protection of dried cells from heat-induced membrane damage.

  10. Circular Dichrosim Studies on the Deinococcus Radiodurans Nudix Hydrolase DR_0079: an Atypical Thermal Melt

    Energy Technology Data Exchange (ETDEWEB)

    Buchko, Garry W.

    2010-07-01

    We have recently determined the solution structure of the hypothetical Deinococcus radiodurans Nudix protein DR0079 [Proteins 56:28-39]. The protein is a monomer and contains the fundamental fold common to the Nudix family, a large mixed b-sheet sandwiched between a-helices. The protein¹s physical properties were further characterized by circular dichroism (CD) spectroscopy. A CD thermal melt indicates an inflection point at ~52ºC. However, unlike typical CD thermal melts, the ellipticity at 220 nm decreases upon passing through the inflection point suggesting that the amount of secondary structure in the protein has increased after heating. NMR spectroscopy and size exclusion chromatography indicates that heating effects the irreversible formation of a large molecular weight complex. After cooling, the ellipiticity at 220 nm increases further, and overall, the CD spectrum at 25ºC shows that heat-treated DR0079 has more ³structure² than non-heat treated DR0079.

  11. Identification and evaluation of the role of the manganese efflux protein in Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Tian Bing

    2010-12-01

    Full Text Available Abstract Background Deinococcus radiodurans accumulates high levels of manganese ions, and this is believed to be correlated with the radiation resistance ability of this microorganism. However, the maintenance of manganese ion homeostasis in D. radiodurans remains to be investigated. Results In this study, we identified the manganese efflux protein (MntE in D. radiodurans. The null mutant of mntE was more sensitive than the wild-type strain to manganese ions, and the growth of the mntE mutant was delayed in manganese-supplemented media. Furthermore, there was a substantial increase in the in vivo concentration of manganese ions. Consistent with these characteristics, the mntE mutant was more resistant to H2O2, ultraviolet rays, and γ-radiation. The intracellular protein oxidation (carbonylation level of the mutant strain was remarkably lower than that of the wild-type strain. Conclusions Our results indicated that dr1236 is indeed a mntE homologue and is indispensable for maintaining manganese homeostasis in D. radiodurans. The data also provide additional evidence for the involvement of intracellular manganese ions in the radiation resistance of D. radiodurans.

  12. High-resolution structure of the antibiotic resistance protein NimA from Deinococcus radiodurans.

    Science.gov (United States)

    Leiros, Hanna Kirsti S; Tedesco, Consiglia; McSweeney, Seán M

    2008-06-01

    Many anaerobic human pathogenic bacteria are treated using 5-nitroimidazole-based (5-Ni) antibiotics, a class of inactive prodrugs that contain a nitro group. The nitro group must be activated in an anaerobic one-electron reduction and is therefore dependent on the redox system in the target cells. Antibiotic resistance towards 5-Ni drugs is found to be related to the nim genes (nimA, nimB, nimC, nimD, nimE and nimF), which are proposed to encode a reductase that is responsible for converting the nitro group of the antibiotic into a nonbactericidal amine. A mechanism for the Nim enzyme has been proposed in which two-electron reduction of the nitro group leads to the generation of nontoxic derivatives and confers resistance against these antibiotics. The cofactor was found to be important in the mechanism and was found to be covalently linked to the reactive His71. In this paper, the 1.2 A atomic resolution crystal structure of the 5-nitroimidazole antibiotic resistance protein NimA from Deinococcus radiodurans (DrNimA) is presented. A planar cofactor is clearly visible and well defined in the electron-density map adjacent to His71, the identification of the cofactor and its properties are discussed.

  13. The predatory bacterium Bdellovibrio bacteriovorus aspartyl-tRNA synthetase recognizes tRNAAsn as a substrate.

    Directory of Open Access Journals (Sweden)

    Ariel Alperstein

    Full Text Available The predatory bacterium Bdellovibrio bacteriovorus preys on other Gram-negative bacteria and was predicted to be an asparagine auxotroph. However, despite encoding asparaginyl-tRNA synthetase and glutaminyl-tRNA synthetase, B. bacteriovorus also contains the amidotransferase GatCAB. Deinococcus radiodurans, and Thermus thermophilus also encode both of these aminoacyl-tRNA synthetases with GatCAB. Both also code for a second aspartyl-tRNA synthetase and use the additional aspartyl-tRNA synthetase with GatCAB to synthesize asparagine on tRNAAsn. Unlike those two bacteria, B. bacteriovorus encodes only one aspartyl-tRNA synthetase. Here we demonstrate the lone B. bacteriovorus aspartyl-tRNA synthetase catalyzes aspartyl-tRNAAsn formation that GatCAB can then amidate to asparaginyl-tRNAAsn. This non-discriminating aspartyl-tRNA synthetase with GatCAB thus provides B. bacteriovorus a second route for Asn-tRNAAsn formation with the asparagine synthesized in a tRNA-dependent manner. Thus, in contrast to a previous prediction, B. bacteriovorus codes for a biosynthetic route for asparagine. Analysis of bacterial genomes suggests a significant number of other bacteria may also code for both routes for Asn-tRNAAsn synthesis with only a limited number encoding a second aspartyl-tRNA synthetase.

  14. Seed viability and germination success of Acacia tortilis along land‐use and aridity gradients in the Eastern Sahara

    National Research Council Canada - National Science Library

    Andersen, Gidske Leknæs; Krzywinski, Knut; Gjessing, Håkon K; Pierce, Richard Holton

    2016-01-01

    Our study focuses on the keystone species A cacia tortilis and is the first to investigate the effect of domestic ungulates and aridity on seed viability and germination over an extensive part of the Eastern Sahara...

  15. The Sahara as a Large-Scale Mars Analogue and the Activities of the Ibn Battuta Centre

    Science.gov (United States)

    Ori, G. G.; Dell'Arciprete, I.; Taj Eddine, K.

    2014-07-01

    Sahara has experienced during its long geological history a large number of climatic changes from humid conditions similar to the climatic changes occurred on Mars. Consequently depositional systems show similar depositional patterns.

  16. Were rivers flowing across the Sahara during the last interglacial? Implications for human migration through Africa.

    Science.gov (United States)

    Coulthard, Tom J; Ramirez, Jorge A; Barton, Nick; Rogerson, Mike; Brücher, Tim

    2013-01-01

    Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palaeo river systems could have been active at the key time of human migration across the Sahara. Unexpectedly, it is the most western of these three rivers, the Irharhar river, that represents the most likely route for human migration. The Irharhar river flows directly south to north, uniquely linking the mountain areas experiencing monsoon climates at these times to temperate Mediterranean environments where food and resources would have been abundant. The findings have major implications for our understanding of how humans migrated north through Africa, for the first time providing a quantitative perspective on the probabilities that these routes were viable for human habitation at these times.

  17. Resource Geopolitics: Cold War Technologies, Global Fertilizers, and the Fate of Western Sahara.

    Science.gov (United States)

    Camprubí, Lino

    2015-07-01

    When, after years of geological and geophysical exploration, a phosphate mine was discovered at Bu-Craa in 1964, Western Sahara received renewed geopolitical attention. Several countries competing for the control of the world fertilizer market, including Morocco, Spain, France, and the United States, developed diverging strategies to gain control of the mineral. After intense negotiations revolving around the materiality of mining technologies and involving reserve estimations, sabotage, and flexing of diplomatic muscles, Morocco took over the Spanish colony in 1975. While this secured Morocco's place in the world market, it condemned the local population to exile and domination. This article explores three technological stages of the exploitation of phosphate in Western Sahara that underpin the geopolitical history. This perspective yields new visions of cold war technology and postcolonial markets.

  18. A tamB homolog is involved in maintenance of cell envelope integrity and stress resistance of Deinococcus radiodurans

    OpenAIRE

    Jiangliu Yu; Tao Li; Shang Dai; Yulan Weng; Jiulong Li; Qinghao Li; Hong Xu; Yuejin Hua; Bing Tian

    2017-01-01

    The translocation and assembly module (TAM) in bacteria consists of TamA and TamB that form a complex to control the transport and secretion of outer membrane proteins. Herein, we demonstrated that the DR_1462-DR_1461-DR_1460 gene loci on chromosome 1 of Deinococcus radiodurans, which lacks tamA homologs, is a tamB homolog (DR_146T) with two tamB motifs and a DUF490 motif. Mutation of DR_146T resulted in cell envelope peeling and a decrease in resistance to shear stress and osmotic pressure, ...

  19. Characterizing the Catalytic Potential of Deinococcus, Arthrobacter and other Robust Bacteria in Contaminated Subsurface Environments of the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Daly, Michael J.

    2005-06-01

    Natural selection in highly radioactive waste sites may yield bacteria with favorable bioremediating characteristics. However, until recently the microbial ecology of such environments has remained unexplored because of the high costs and technical complexities associated with extracting and characterizing samples from such sites. We have examined the bacterial ecology within radioactive sediments from a high-level nuclear waste plume in the vadose zone on the DOE?s Hanford Site in south-central Washington state (Fredrickson et al, 2004). Manganese-dependent, radiation resistant bacteria have been isolated from this contaminated site including the highly Mn-dependent Deinococcus and Arthrobacter spp.

  20. Implementing Apache Spark jobs execution and Apache Spark cluster creation for Openstack Sahara

    OpenAIRE

    ALEKSIYANTS A.; Borisenko, O.; TURDAKOV D.; Sher, A; Kuznetsov, S

    2015-01-01

    In this paper the problem of creating virtual clusters in clouds for big data analysis with Apache Hadoop and Apache Spark is discussed. Existing methods for Apache Spark clusters creation are described in this work. Also the implemented solution for building Apache Spark clusters and Apache Spark jobs execution in Openstack environment is described. The implemented solution is a modification for OpenStack Sahara project and it was featured in Openstack Liberty release.

  1. Sud du Sahara | Page 68 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    flexible layoutflexible layoutflexible layoutflexible layoutflexible layout. Sud du Sahara. La persistance de la pauvreté en Afrique subsaharienne, dans le contexte de progression rapide de la mondialisation et de la libéralisation des échanges commerciaux des deux dernières décennies, a suscité énormément de débats en ...

  2. Sud du Sahara | Page 78 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    flexible layoutflexible layoutflexible layoutflexible layoutflexible layout. Sud du Sahara. La persistance de la pauvreté en Afrique subsaharienne, dans le contexte de progression rapide de la mondialisation et de la libéralisation des échanges commerciaux des deux dernières décennies, a suscité énormément de débats en ...

  3. Sud du Sahara | Page 62 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    flexible layoutflexible layoutflexible layoutflexible layoutflexible layout. Sud du Sahara. La persistance de la pauvreté en Afrique subsaharienne, dans le contexte de progression rapide de la mondialisation et de la libéralisation des échanges commerciaux des deux dernières décennies, a suscité énormément de débats en ...

  4. Microbial Diversity of the Hypersaline Sidi Ameur and Himalatt Salt Lakes of the Algerian Sahara

    OpenAIRE

    Boutaiba, Saad; Hacene, Hocine; Bidle, Kelly A.; Maupin-Furlow, Julie A.

    2011-01-01

    Microbial populations within hypersaline lakes often exhibit high activities of photosynthesis, dissimilatory sulphate reduction and other processes and, thus, can have profound impacts on biogeochemical cycles of carbon, nitrogen, sulphur and other important elements within arid lands. To further understand these types of ecosystems, the physicochemical and biological properties of Sidi Ameur and Himalatt Salt Lakes in the Algerian Sahara were examined and compared. Both lakes were relativel...

  5. Tropical cyclone activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period

    Science.gov (United States)

    Pausata, Francesco S. R.; Emanuel, Kerry A.; Chiacchio, Marc; Diro, Gulilat T.; Zhang, Qiong; Sushama, Laxmi; Stager, J. Curt; Donnelly, Jeffrey P.

    2017-06-01

    Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it is of interest to apply physical modeling to understanding TC variability under different climate conditions. Here we investigate global TC activity during a warm climate state (mid-Holocene, 6,000 yBP) characterized by increased boreal summer insolation, a vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity experiments in which not only solar insolation changes are varied but also vegetation and dust concentrations. Our results show that the greening of the Sahara and reduced dust loadings lead to more favorable conditions for tropical cyclone development compared with the orbital forcing alone. In particular, the strengthening of the West African Monsoon induced by the Sahara greening triggers a change in atmospheric circulation that affects the entire tropics. Furthermore, whereas previous studies suggest lower TC activity despite stronger summer insolation and warmer sea surface temperature in the Northern Hemisphere, accounting for the Sahara greening and reduced dust concentrations leads instead to an increase of TC activity in both hemispheres, particularly over the Caribbean basin and East Coast of North America. Our study highlights the importance of regional changes in land cover and dust concentrations in affecting the potential intensity and genesis of past TCs and suggests that both factors may have appreciable influence on TC activity in a future warmer climate.

  6. Tropical cyclone activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period.

    Science.gov (United States)

    Pausata, Francesco S R; Emanuel, Kerry A; Chiacchio, Marc; Diro, Gulilat T; Zhang, Qiong; Sushama, Laxmi; Stager, J Curt; Donnelly, Jeffrey P

    2017-06-13

    Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it is of interest to apply physical modeling to understanding TC variability under different climate conditions. Here we investigate global TC activity during a warm climate state (mid-Holocene, 6,000 yBP) characterized by increased boreal summer insolation, a vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity experiments in which not only solar insolation changes are varied but also vegetation and dust concentrations. Our results show that the greening of the Sahara and reduced dust loadings lead to more favorable conditions for tropical cyclone development compared with the orbital forcing alone. In particular, the strengthening of the West African Monsoon induced by the Sahara greening triggers a change in atmospheric circulation that affects the entire tropics. Furthermore, whereas previous studies suggest lower TC activity despite stronger summer insolation and warmer sea surface temperature in the Northern Hemisphere, accounting for the Sahara greening and reduced dust concentrations leads instead to an increase of TC activity in both hemispheres, particularly over the Caribbean basin and East Coast of North America. Our study highlights the importance of regional changes in land cover and dust concentrations in affecting the potential intensity and genesis of past TCs and suggests that both factors may have appreciable influence on TC activity in a future warmer climate.

  7. Low-Temperature Ionizing Radiation Resistance of Deinococcus radiodurans and Antarctic Dry Valley Bacteria

    Science.gov (United States)

    Dartnell, Lewis R.; Hunter, Stephanie J.; Lovell, Keith V.; Coates, Andrew J.; Ward, John M.

    2010-09-01

    The high flux of cosmic rays onto the unshielded surface of Mars poses a significant hazard to the survival of martian microbial life. Here, we determined the survival responses of several bacterial strains to ionizing radiation exposure while frozen at a low temperature characteristic of the martian near-subsurface. Novel psychrotolerant bacterial strains were isolated from the Antarctic Dry Valleys, an environmental analogue of the martian surface, and identified by 16S rRNA gene phylogeny as representatives of Brevundimonas, Rhodococcus, and Pseudomonas genera. These isolates, in addition to the known radioresistant extremophile Deinococcus radiodurans, were exposed to gamma rays while frozen on dry ice (-79°C). We found D. radiodurans to exhibit far greater radiation resistance when irradiated at -79°C than was observed in similar studies performed at higher temperatures. This greater radiation resistance has important implications for the estimation of potential survival times of microorganisms near the martian surface. Furthermore, the most radiation resistant of these Dry Valley isolates, Brevundimonas sp. MV.7, was found to show 99% 16S rRNA gene similarity to contaminant bacteria discovered in clean rooms at both Kennedy and Johnson Space Centers and so is of prime concern to efforts in the planetary protection of Mars from our lander probes. Results from this experimental irradiation, combined with previous radiation modeling, indicate that Brevundimonas sp. MV.7 emplaced only 30 cm deep in martian dust could survive the cosmic radiation for up to 100,000 years before suffering 106 population reduction.

  8. Divisome and segrosome components of Deinococcus radiodurans interact through cell division regulatory proteins.

    Science.gov (United States)

    Maurya, Ganesh K; Modi, Kruti; Misra, Hari S

    2016-08-01

    The Deinococcus radiodurans genome encodes many of the known components of divisome as well as four sets of genome partitioning proteins, ParA and ParB on its multipartite genome. Interdependent regulation of cell division and genome segregation is not understood. In vivo interactions of D. radiodurans' sdivisome, segrosome and other cell division regulatory proteins expressed on multicopy plasmids were studied in Escherichia coli using a bacterial two-hybrid system and confirmed by co-immunoprecipitation with the proteins made in E. coli. Many of these showed interactions both with the self and with other proteins. For example, DrFtsA, DrFtsZ, DrMinD, DrMinC, DrDivIVA and all four ParB proteins individually formed at least homodimers, while DrFtsA interacted with DrFtsZ, DrFtsW, DrFtsE, DrFtsK and DrMinD. DrMinD also showed interaction with DrFtsW, DrFtsE and DrMinC. Interestingly, septum site determining protein, DrDivIVA showed interactions with secondary genome ParAs as well as ParB1, ParB3 and ParB4 while DrMinC interacted with ParB1 and ParB3. PprA, a pleiotropic protein recently implicated in cell division regulation, neither interacted with divisome proteins nor ParBs but interacted at different levels with all four ParAs. These results suggest the formation of independent multiprotein complexes of 'DrFts' proteins, segrosome proteins and cell division regulatory proteins, and these complexes could interact with each other through DrMinC and DrDivIVA, and PprA in D. radiodurans.

  9. Topoisomerase IB of Deinococcus radiodurans resolves guanine quadruplex DNA structures in vitro.

    Science.gov (United States)

    Kota, Swathi; Misra, Hari S

    2015-12-01

    Deinococcus radiodurans genome contains a large number of guanine repeats interrupted by a few non-guanine bases, termed G motifs. Some of these G motifs were shown forming guanine quadruplex (G4) DNA structure in vitro. How is the formation and relaxation of G4 DNA regulated in the genome of D. radiodurans is not known and is worth investigating. Here, we showed that the topoisomerase Ib of D. radiodurans (DraTopoIB) could change the electrophoretic mobility of fast migrating intramolecular recF-G4 DNA into the slow migrating species. DraTopoIB also reduced the positive ellipticity in circular diachroism (CD) spectra of intramolecular recF-G4 DNA structures stabilized by K+. On the contrary, when DraTopoIB is incubated with G-motifs annealed without K+, it showed neither any change in electrophoretic mobility nor was ellipticity of the CD spectra affected. DNA synthesis by Taq DNA polymerase through G4 DNA structure was attenuated in the presence of G4 DNA binding drugs, which was abrogated by DraTopoIB. This implies that DraTopoIB could destabilize the G4 DNA structure, which is required for G4 drugs binding and stabilization. Camptothecin treatment inhibited DraTopoIB activity on intramolecular G4 DNA structures. These results suggested that DraTopoIB can relax intramolecular G4 DNA structure in vitro and it may be one such protein that could resolve G4 DNA under normal growth conditions in D. radiodurans.

  10. Gamma Radiation-induced Proteome of Deinococcus radiodurans Primarily Targets DNA Repair and Oxidative Stress Alleviation*

    Science.gov (United States)

    Basu, Bhakti; Apte, Shree Kumar

    2012-01-01

    The extraordinary radioresistance of Deinococcus radiodurans primarily originates from its efficient DNA repair ability. The kinetics of proteomic changes induced by a 6-kGy dose of gamma irradiation was mapped during the post-irradiation growth arrest phase by two-dimensional protein electrophoresis coupled with mass spectrometry. The results revealed that at least 37 proteins displayed either enhanced or de novo expression in the first 1 h of post-irradiation recovery. All of the radiation-responsive proteins were identified, and they belonged to the major functional categories of DNA repair, oxidative stress alleviation, and protein translation/folding. The dynamics of radiation-responsive protein levels throughout the growth arrest phase demonstrated (i) sequential up-regulation and processing of DNA repair proteins such as single-stranded DNA-binding protein (Ssb), DNA damage response protein A (DdrA), DNA damage response protein B (DdrB), pleiotropic protein promoting DNA repair (PprA), and recombinase A (RecA) substantiating stepwise genome restitution by different DNA repair pathways and (ii) concurrent early up-regulation of proteins involved in both DNA repair and oxidative stress alleviation. Among DNA repair proteins, Ssb was found to be the first and most abundant radiation-induced protein only to be followed by alternate Ssb, DdrB, indicating aggressive protection of single strand DNA fragments as the first line of defense by D. radiodurans, thereby preserving genetic information following radiation stress. The implications of both qualitative or quantitative and sequential or co-induction of radiation-responsive proteins for envisaged DNA repair mechanism in D. radiodurans are discussed. PMID:21989019

  11. Enhanced DNA binding affinity of RecA protein from Deinococcus radiodurans.

    Science.gov (United States)

    Warfel, Jaycob D; LiCata, Vince J

    2015-07-01

    Deinococcus radiodurans (Dr) has a significantly more robust DNA repair response than Escherichia coli (Ec), which helps it survive extremely high doses of ionizing radiation and prolonged periods of desiccation. DrRecA protein plays an essential part in this DNA repair capability. In this study we directly compare the binding of DrRecA and EcRecA to the same set of short, defined single (ss) and double stranded (ds) DNA oligomers. In the absence of cofactors (ATPγS or ADP), DrRecA binds to dsDNA oligomers more than 20 fold tighter than EcRecA, and binds ssDNA up to 9 fold tighter. Binding to dsDNA oligomers in the absence of cofactor presumably predominantly monitors DNA end binding, and thus suggests a significantly higher affinity of DrRecA for ds breaks. Upon addition of ATPγS, this species-specific affinity difference is nearly abolished, as ATPγS significantly decreases the affinity of DrRecA for DNA. Other findings include that: (1) both proteins exhibit a dependence of binding affinity on the length of the ssDNA oligomer, but not the dsDNA oligomer; (2) the salt dependence of binding is modest for both species of RecA, and (3) in the absence of DNA, DrRecA produces significantly shorter and/or fewer free-filaments in solution than does EcRecA. The results suggest intrinsic biothermodynamic properties of DrRecA contribute directly to the more robust DNA repair capabilities of D. radiodurans. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. The DnaE polymerase from Deinococcus radiodurans features RecA-dependent DNA polymerase activity.

    Science.gov (United States)

    Randi, Lorenzo; Perrone, Alessandro; Maturi, Mirko; Dal Piaz, Fabrizio; Camerani, Michela; Hochkoeppler, Alejandro

    2016-12-01

    We report in the present study on the catalytic properties of the Deinococcus radiodurans DNA polymerase III α subunit (αDr). The αDr enzyme was overexpressed in Escherichia coli, both in soluble form and as inclusion bodies. When purified from soluble protein extracts, αDr was found to be tightly associated with E. coli RNA polymerase, from which αDr could not be dissociated. On the contrary, when refolded from inclusion bodies, αDr was devoid of E. coli RNA polymerase and was purified to homogeneity. When assayed with different DNA substrates, αDr featured slower DNA extension rates when compared with the corresponding enzyme from E. coli (E. coli DNA Pol III, αEc), unless under high ionic strength conditions or in the presence of manganese. Further assays were performed using a ssDNA and a dsDNA, whose recombination yields a DNA substrate. Surprisingly, αDr was found to be incapable of recombination-dependent DNA polymerase activity, whereas αEc was competent in this action. However, in the presence of the RecA recombinase, αDr was able to efficiently extend the DNA substrate produced by recombination. Upon comparing the rates of RecA-dependent and RecA-independent DNA polymerase activities, we detected a significant activation of αDr by the recombinase. Conversely, the activity of αEc was found maximal under non-recombination conditions. Overall, our observations indicate a sharp contrast between the catalytic actions of αDr and αEc, with αDr more performing under recombination conditions, and αEc preferring DNA substrates whose extension does not require recombination events. © 2016 The Author(s).

  13. High Resolution Structure of Deinococcus Bacteriophytochrome Yields New Insights into Phytochrome Architecture and Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Jeremiah R.; Zhang, Junrui; Brunzelle, Joseph S.; Vierstra, Richard D.; Forest, Katrina T. (NWU); (UW)

    2010-03-08

    Phytochromes are red/far red light photochromic photoreceptors that direct many photosensory behaviors in the bacterial, fungal, and plant kingdoms. They consist of an N-terminal domain that covalently binds a bilin chromophore and a C-terminal region that transmits the light signal, often through a histidine kinase relay. Using x-ray crystallography, we recently solved the first three-dimensional structure of a phytochrome, using the chromophore-binding domain of Deinococcus radiodurans bacterial phytochrome assembled with its chromophore, biliverdin IX{alpha}. Now, by engineering the crystallization interface, we have achieved a significantly higher resolution model. This 1.45 {angstrom} resolution structure helps identify an extensive buried surface between crystal symmetry mates that may promote dimerization in vivo. It also reveals that upon ligation of the C3{sup 2} carbon of biliverdin to Cys{sup 24}, the chromophore A-ring assumes a chiral center at C2, thus becoming 2(R),3(E)-phytochromobilin, a chemistry more similar to that proposed for the attached chromophores of cyanobacterial and plant phytochromes than previously appreciated. The evolution of bacterial phytochromes to those found in cyanobacteria and higher plants must have involved greater fitness using more reduced bilins, such as phycocyanobilin, combined with a switch of the attachment site from a cysteine near the N terminus to one conserved within the cGMP phosphodiesterase/adenyl cyclase/FhlA domain. From analysis of site-directed mutants in the D. radiodurans phytochrome, we show that this bilin preference was partially driven by the change in binding site, which ultimately may have helped photosynthetic organisms optimize shade detection. Collectively, these three-dimensional structural results better clarify bilin/protein interactions and help explain how higher plant phytochromes evolved from prokaryotic progenitors.

  14. Structural and mechanistic insight into DNA unwinding by Deinococcus radiodurans UvrD.

    Directory of Open Access Journals (Sweden)

    Meike Stelter

    Full Text Available DNA helicases are responsible for unwinding the duplex DNA, a key step in many biological processes. UvrD is a DNA helicase involved in several DNA repair pathways. We report here crystal structures of Deinococcus radiodurans UvrD (drUvrD in complex with DNA in different nucleotide-free and bound states. These structures provide us with three distinct snapshots of drUvrD in action and for the first time trap a DNA helicase undergoing a large-scale spiral movement around duplexed DNA. Our structural data also improve our understanding of the molecular mechanisms that regulate DNA unwinding by Superfamily 1A (SF1A helicases. Our biochemical data reveal that drUvrD is a DNA-stimulated ATPase, can translocate along ssDNA in the 3'-5' direction and shows ATP-dependent 3'-5', and surprisingly also, 5'-3' helicase activity. Interestingly, we find that these translocase and helicase activities of drUvrD are modulated by the ssDNA binding protein. Analysis of drUvrD mutants indicate that the conserved β-hairpin structure of drUvrD that functions as a separation pin is critical for both drUvrD's 3'-5' and 5'-3' helicase activities, whereas the GIG motif of drUvrD involved in binding to the DNA duplex is essential for the 5'-3' helicase activity only. These special features of drUvrD may reflect its involvement in a wide range of DNA repair processes in vivo.

  15. Low-temperature ionizing radiation resistance of Deinococcus radiodurans and Antarctic Dry Valley bacteria.

    Science.gov (United States)

    Dartnell, Lewis R; Hunter, Stephanie J; Lovell, Keith V; Coates, Andrew J; Ward, John M

    2010-09-01

    The high flux of cosmic rays onto the unshielded surface of Mars poses a significant hazard to the survival of martian microbial life. Here, we determined the survival responses of several bacterial strains to ionizing radiation exposure while frozen at a low temperature characteristic of the martian near-subsurface. Novel psychrotolerant bacterial strains were isolated from the Antarctic Dry Valleys, an environmental analogue of the martian surface, and identified by 16S rRNA gene phylogeny as representatives of Brevundimonas, Rhodococcus, and Pseudomonas genera. These isolates, in addition to the known radioresistant extremophile Deinococcus radiodurans, were exposed to gamma rays while frozen on dry ice (-79°C). We found D. radiodurans to exhibit far greater radiation resistance when irradiated at -79°C than was observed in similar studies performed at higher temperatures. This greater radiation resistance has important implications for the estimation of potential survival times of microorganisms near the martian surface. Furthermore, the most radiation resistant of these Dry Valley isolates, Brevundimonas sp. MV.7, was found to show 99% 16S rRNA gene similarity to contaminant bacteria discovered in clean rooms at both Kennedy and Johnson Space Centers and so is of prime concern to efforts in the planetary protection of Mars from our lander probes. Results from this experimental irradiation, combined with previous radiation modeling, indicate that Brevundimonas sp. MV.7 emplaced only 30 cm deep in martian dust could survive the cosmic radiation for up to 100,000 years before suffering 10⁶ population reduction.

  16. Biophysical characterization and mutational analysis of the antibiotic resistance protein NimA from Deinococcus radiodurans.

    Science.gov (United States)

    Leiros, Hanna-Kirsti S; Brandsdal, Bjørn Olav; McSweeney, Seán M

    2010-04-01

    Metronidazole (MTZ) is an antibiotic commonly used to treat anaerobic bacterial infections in humans and animals. Antibiotic resistance toward this class of 5-nitroimidazole (5-Ni) drug derivatives has been related to the Nim genes thought to encode a reductase. Here we report the biophysical characteristics of the NimA protein from Deinococcus radiodurans (DrNimA) binding to MTZ and three other 5-Ni drugs. The interaction energies of the protein and antibiotic are studied by isothermal titration calorimetry (ITC) and with free energy and linear interaction energy (LIE) calculations, where the latter method revealed that the antibiotic binding is mainly of hydrophobic character. ITC measurements further found that one DrNimA dimer has two antibiotic binding sites which were not affected by mutation of the reactive His71. The observed association constants (K(a)) were in the range of 5.1-4910(4)M(-1) and the enthalpy release upon binding to DrNimA for the four drugs studied was relatively low (approximately -1 kJ/mol) but still measurable. The drug binding is mainly entropy driven and along with the hydrophobic drug binding site found by crystallography, this possibly explains the low observed enthalpy values. The effect of the His71 mutation and the presence of MTZ were studied by differential scanning calorimetry (DSC). Native DrNimA is a yellow colored protein where the interaction from His71 to the cofactor is thought to be responsible for the coloring. Mutations of His71 to Ala, Ser, Leu or Asp all gave transparent, colorless protein solutions, and the two mutant crystal structures of DrNimA-H71A and DrNimA-H71S presented revealed no cofactor binding. Copyright 2010 Elsevier B.V. All rights reserved.

  17. Zymomonas mobilis: a bacterium for ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Baratti, J.C.; Bu' Lock, J.D.

    1986-01-01

    Zymomonas mobilis is a facultative anaerobic gram negative bacterium first isolated in tropical countries from alcoholic beverages like the African palm wine, the Mexican pulque and also as a contaminant of cider (cider sickness) or beer in the European countries. It is one of the few facultative anaerobic bacteria degrading glucose by the Entner-Doudoroff pathway usually found in strictly aerobic microorganisms. Some work was devoted to this bacterium in the 50s and 60s and was reviewed by Swings and De Ley in their classical paper published in 1977. During the 70s there was very little work on the bacterium until 1979 and the first report by the Australian group of P.L. Rogers on the great potentialities of Z. mobilis for ethanol production. At that time the petroleum crisis had led the developed countries to search for alternative fuel from renewable resources. The Australian group clearly demonstrated the advantages of the bacterium compared to the yeasts traditionally used for the alcoholic fermentation. As a result, there was a considerable burst in the Zymomonas literature which started from nearly zero in the late 70s to attain 70 papers published in the field in 1984. In this article, papers published from 1982 to 1986 are reviewed.

  18. The Structure of DdrB from Deinococcus: a New Fold for Single-stranded DNA Binding Proteins

    Energy Technology Data Exchange (ETDEWEB)

    Sugiman-Marangos, S.; Junop, M

    2010-01-01

    Deinococcus spp. are renowned for their amazing ability to recover rapidly from severe genomic fragmentation as a result of exposure to extreme levels of ionizing radiation or desiccation. Despite having been originally characterized over 50 years ago, the mechanism underlying this remarkable repair process is still poorly understood. Here, we report the 2.8 {angstrom} structure of DdrB, a single-stranded DNA (ssDNA) binding protein unique to Deinococcus spp. that is crucial for recovery following DNA damage. DdrB forms a pentameric ring capable of binding single-stranded but not double-stranded DNA. Unexpectedly, the crystal structure reveals that DdrB comprises a novel fold that is structurally and topologically distinct from all other single-stranded binding (SSB) proteins characterized to date. The need for a unique ssDNA binding function in response to severe damage, suggests a distinct role for DdrB which may encompass not only standard SSB protein function in protection of ssDNA, but also more specialized roles in protein recruitment or DNA architecture maintenance. Possible mechanisms of DdrB action in damage recovery are discussed.

  19. A Genome-Wide Search for Ionizing-Radiation-Responsive Elements in Deinococcus radiodurans Reveals a Regulatory Role for the DNA Gyrase Subunit A Gene's 5' Untranslated Region in the Radiation and Desiccation Response.

    Science.gov (United States)

    Villa, Jordan K; Amador, Paul; Janovsky, Justin; Bhuyan, Arijit; Saldanha, Roland; Lamkin, Thomas J; Contreras, Lydia M

    2017-06-15

    Tight regulation of gene expression is important for the survival of Deinococcus radiodurans, a model bacterium of extreme stress resistance. Few studies have examined the use of regulatory RNAs as a possible contributing mechanism to ionizing radiation (IR) resistance, despite their proffered efficient and dynamic gene expression regulation under IR stress. This work presents a transcriptome-based approach for the identification of stress-responsive regulatory 5' untranslated region (5'-UTR) elements in D. radiodurans R1 that can be broadly applied to other bacteria. Using this platform and an in vivo fluorescence screen, we uncovered the presence of a radiation-responsive regulatory motif in the 5' UTR of the DNA gyrase subunit A gene. Additional screens under H2O2-induced oxidative stress revealed the specificity of the response of this element to IR stress. Further examination of the sequence revealed a regulatory motif of the radiation and desiccation response (RDR) in the 5' UTR that is necessary for the recovery of D. radiodurans from high doses of IR. Furthermore, we suggest that it is the preservation of predicted RNA structure, in addition to DNA sequence consensus of the motif, that permits this important regulatory ability.IMPORTANCEDeinococcus radiodurans is an extremely stress-resistant bacterium capable of tolerating up to 3,000 times more ionizing radiation than human cells. As an integral part of the stress response mechanism of this organism, we suspect that it maintains stringent control of gene expression. However, understanding of its regulatory pathways remains incomplete to date. Untranslated RNA elements have been demonstrated to play crucial roles in gene regulation throughout bacteria. In this work, we focus on searching for and characterizing responsive RNA elements under radiation stress and propose that multiple levels of gene regulation work simultaneously to enable this organism to efficiently recover from exposure to ionizing

  20. The role of Deinococcus radiodurans RecFOR proteins in homologous recombination.

    Science.gov (United States)

    Satoh, Katsuya; Kikuchi, Masahiro; Ishaque, Abu M; Ohba, Hirofumi; Yamada, Mitsugu; Tejima, Kouhei; Onodera, Takefumi; Narumi, Issay

    2012-04-01

    Deinococcus radiodurans exhibits extraordinary resistance to the lethal effect of DNA-damaging agents, a characteristic attributed to its highly proficient DNA repair capacity. Although the D. radiodurans genome is clearly devoid of recBC and addAB counterparts as RecA mediators, the genome possesses all genes associated with the RecFOR pathway. In an effort to gain insights into the role of D. radiodurans RecFOR proteins in homologous recombination, we generated recF, recO and recR disruptant strains and characterized the disruption effects. All the disruptant strains exhibited delayed growth relative to the wild-type, indicating that the RecF, RecO and RecR proteins play an important role in cell growth under normal growth conditions. A slight reduction in transformation efficiency was observed in the recF and recO disruptant strains compared to the wild-type strain. Interestingly, disruption of recR resulted in severe reduction of the transformation efficiency. On the other hand, the recF disruptant strain was the most sensitive phenotype to γ rays, UV irradiation and mitomycin C among the three disruptants. In the recF disruptant strain, the intracellular level of the LexA1 protein did not decrease following γ irradiation, suggesting that a large amount of the RecA protein remains inactive despite being induced. These results demonstrate that the RecF protein plays a crucial role in the homologous recombination repair process by facilitating RecA activation in D. radiodurans. Thus, the RecF and RecR proteins are involved in the RecA activation and the stability of incoming DNA, respectively, during RecA-mediated homologous recombination processes that initiated the ESDSA pathway in D. radiodurans. Possible mechanisms that involve the RecFOR complex in homologous intermolecular recombination and homologous recombination repair processes are also discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Imposed Environmental Stresses Facilitate Cell-Free Nanoparticle Formation by Deinococcus radiodurans.

    Science.gov (United States)

    Chen, Angela; Contreras, Lydia M; Keitz, Benjamin K

    2017-09-15

    The biological synthesis of metal nanoparticles has been examined in a wide range of organisms, due to increased interest in green synthesis and environmental remediation applications involving heavy metal ion contamination. Deinococcus radiodurans is particularly attractive for environmental remediation involving metal reduction, due to its high levels of resistance to radiation and other environmental stresses. However, few studies have thoroughly examined the relationships between environmental stresses and the resulting effects on nanoparticle biosynthesis. In this work, we demonstrate cell-free nanoparticle production and study the effects of metal stressor concentrations and identity, temperature, pH, and oxygenation on the production of extracellular silver nanoparticles by D. radiodurans R1. We also report the synthesis of bimetallic silver and gold nanoparticles following the addition of a metal stressor (silver or gold), highlighting how production of these particles is enabled through the application of environmental stresses. Additionally, we found that both the morphology and size of monometallic and bimetallic nanoparticles were dependent on the environmental stresses imposed on the cells. The nanoparticles produced by D. radiodurans exhibited antimicrobial activity comparable to that of pure silver nanoparticles and displayed catalytic activity comparable to that of pure gold nanoparticles. Overall, we demonstrate that biosynthesized nanoparticle properties can be partially controlled through the tuning of applied environmental stresses, and we provide insight into how their application may affect nanoparticle production in D. radiodurans during bioremediation.IMPORTANCE Biosynthetic production of nanoparticles has recently gained prominence as a solution to rising concerns regarding increased bacterial resistance to antibiotics and a desire for environmentally friendly methods of bioremediation and chemical synthesis. To date, a range of organisms

  2. The effects of space travel to Deinococcus radiodurans and the carotenoid Deinoxanthin

    Science.gov (United States)

    Rettberg, Petra; De Vera, Jean-Pierre; Bohmeier, Maria; Leuko, Stefan; Boettger, Ute; Hanke, Franziska

    Carotenoids are common, vital components of many organisms. They (1) protect chlorophyll from oxidative damage; (2) create harmless products from toxic singlet oxygen; (3) assist light absorption in chloroplasts as they collect energy in the spectrum where chlorophyll cannot; (4) transport harvested light energy to retinal based proton pumps; and (5) provide structure via the polyene chain to plastid membranes (Winters et al. 2013). More than 600 carotenoids have been isolated from natural sources and there is a rising interest in the use of carotenoids as possible biomarkers for life on other planets. It is therefore of great interest to investigate if the harboring organisms and the associated carotenoids are able to cope with simulated and real space conditions. These questions are addressed by the Low Earth Orbit (LEO) experiment Biology and Mars experiment (BIOMEX). BIOMEX is an interdisciplinary and international space research project and the prime objective is to measure to what extent biomarkers are resistant to and able to maintain their stability under space and Mars-like conditions. Part of the research focusses on the extreme radiation resistant Deinococcus radiodurans and the effect and influence of Deinoxanthin to fitness and survival following exposure to space conditions. Furthermore, the resistance of crude extracted Deinoxanthin to space conditions is of great interest and was tested. As part of environmental verification tests (EVT’s), D. radiodurans and D. radiodurans ΔcrtB (a mutant not able to produce Deinoxanthin) were exposed to several space relevant environmental factors. Interestingly, both strains showed similar survival abilities. To investigate if the carotenoid within the cell took damage, samples were investigated by RAMAN spectroscopy. Raman spectroscopy is a non-destructive technique, the feasibility of this method which is able to detect carotenoids is well known and has been proposed to be onboard the ExoMars mission

  3. Assimilation of MODIS AOD measurements during the Sahara dust episode in April 2016

    Science.gov (United States)

    Scherllin-Pirscher, Barbara; Hirtl, Marcus; Flandorfer, Claudia; Pagowski, Mariusz

    2017-04-01

    In April 2016, an air pollution event with highly elevated surface concentrations of particulate matter (PM) has been observed in Europe. At the Sonnblick observatory (an atmospheric monitoring platform at 3100 m in the Alps in Austria), PM10 surface concentrations were considerably elevated (>100 μg/m3) on April 5, 2016. This event was caused by a Sahara dust storm. In this study we use the WRF-Chem (Weather Research and Forecasting model coupled with Chemistry) model to predict the transport of Sahara dust from northern Africa towards Europe. Simulations were performed from April 1, 2016 to April 8, 2016 using the GOCART (Goddard Chemistry Aerosol Radiation and Transport) aerosol scheme. The GOCART model simulates tropospheric aerosols such as dust and sea salt (both with different size bins), organic carbon (OC), black carbon (BC), and sulfate, enabling the computation of PM2.5 and PM10. Gridpoint statistical interpolation (GSI) is then used to assimilate data of the Moderate Resolution Imaging Spectroradiometer (MODIS) total aerosol optical depth (AOD) retrieval products at a wavelength of 550 nm from the Terra and Aqua satellites. Data assimilation is performed at 12 UTC with an assimilation window of ±3 hours. PM10 analyses are evaluated against PM10 surface measurements provided by EEA (European Environment Agency) and the Austrian Environmental Agency. First results indicate that WRF-Chem underestimates surface concentration of PM10 during the Sahara dust event in April 2016 over Europe but the assimilation of MODIS AOD substantially improves PM10 analyses.

  4. Inputs, productivity, and agricultural growth in Africa South of the Sahara:

    OpenAIRE

    Nin-Pratt, Alejandro

    2015-01-01

    The evidence of improved performance of agriculture in Africa south of the Sahara (SSA) in recent years has indeed been quite striking when compared with the past. For the first time, the sector has maintained a real growth rate of 3.4 percent per year, well above the population growth rate of 2.5 percent. Despite this improved performance, agricultural productivity growth in SSA continues to lag behind every other region of the world, growing at rates that are roughly half of the average rat...

  5. Does wintering north or south of the Sahara correlate with timing and breeding performance in black-tailed godwits?

    Science.gov (United States)

    Kentie, Rosemarie; Marquez-Ferrando, Rocío; Figuerola, Jordi; Gangoso, Laura; Hooijmeijer, Jos C E W; Loonstra, A H Jelle; Robin, Frédéric; Sarasa, Mathieu; Senner, Nathan; Valkema, Haije; Verhoeven, Mo A; Piersma, Theunis

    2017-04-01

    Migrating long distances requires time and energy, and may interact with an individual's performance during breeding. These seasonal interactions in migratory animals are best described in populations with disjunct nonbreeding distributions. The black-tailed godwit (Limosa limosa limosa), which breeds in agricultural grasslands in Western Europe, has such a disjunct nonbreeding distribution: The majority spend the nonbreeding season in West Africa, while a growing number winters north of the Sahara on the Iberian Peninsula. To test whether crossing the Sahara has an effect on breeding season phenology and reproductive parameters, we examined differences in the timing of arrival, breeding habitat quality, lay date, egg volume, and daily nest survival among godwits (154 females and 157 males), individually marked in a breeding area in the Netherlands for which wintering destination was known on the basis of resightings. We also examined whether individual repeatability in arrival date differed between birds wintering north or south of the Sahara. Contrary to expectation, godwits wintering south of the Sahara arrived two days earlier and initiated their clutch six days earlier than godwits wintering north of the Sahara. Arrival date was equally repeatable for both groups, and egg volume larger in birds wintering north of the Sahara. Despite these differences, we found no association between wintering location and the quality of breeding habitat or nest survival. This suggests that the crossing of an important ecological barrier and doubling of the migration distance, twice a year, do not have clear negative reproductive consequences for some long-distance migrants.

  6. In situ real-time evaluation of radiation-responsive promoters in the extremely radioresistant microbe Deinococcus radiodurans.

    Science.gov (United States)

    Anaganti, Narasimha; Basu, Bhakti; Apte, Shree Kumar

    2016-06-01

    A third generation promoter probe shuttle vector pKG was constructed, using the green fluorescent protein as a reporter, for in situ evaluation of Deinococcal promoter activity in Escherichia coli or Deinococcus radiodurans. The construct yielded zero background fluorescence in both the organisms, in the absence of promoter sequences. Fifteen Deinococcal promoters, either harbouring Radiation and Desiccation Response Motif (RDRM) or not, were cloned in vector pKG. Only the RDRM-promoter constructs displayed (i) gamma radiation inducible GFP expression in D. radiodurans, following gamma irradiation, (ii) DdrO-mediated repression of GFP expression in heterologous E. coli, or (iii) abolition in GFP induction following gamma irradiation, in pprI mutant of D. radiodurans. Utility of pKG vector for real-time in situ assessment of Deinococcal promoter function was, thus, successfully demonstrated.

  7. Effect of N+ Beam Exposure on Superoxide Dismutase and Catalase Activities and Induction of Mn-SOD in Deinococcus Radiodurans

    Science.gov (United States)

    Song, Dao-jun; Chen, Ruo-lei; Shao, Chun-lin; Wu, Li-jun; Yu, Zeng-liang

    2000-10-01

    Though bacteria of the radiation-resistant Deinococcus radiodurans have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these bacteria to oxidative stress are poorly understood. In this report, the superoxide dismutase (SOD) and catalase (CAT) activities produced by these bacteria were measured, and the change of SOD and CAT activities by 20 keV N+ beam exposure was examined. Their activities were increased by N+ beam exposure from 8×1014 ions/cm2 to 6×1015 ions/cm2. The treatment of H2O2 and [CHCl3 +CH3CH2OH] and the measurement of absorption spectrum showed that the increase in SOD activity was resulted from inducible activities of Mn-SOD in D. radiodurans AS1.633 by N+ beam exposure. These results suggested that this bacteria possess inducible defense mechanisms against the deleterious effects of oxidization.

  8. The N253F mutant structure of trehalose synthase from Deinococcus radiodurans reveals an open active-site topology.

    Science.gov (United States)

    Chow, Sih Yao; Wang, Yung Lin; Hsieh, Yu Chiao; Lee, Guan Chiun; Liaw, Shwu Huey

    2017-11-01

    Trehalose synthase (TS) catalyzes the reversible conversion of maltose to trehalose and belongs to glycoside hydrolase family 13 (GH13). Previous mechanistic analysis suggested a rate-limiting protein conformational change, which is probably the opening and closing of the active site. Consistently, crystal structures of Deinococcus radiodurans TS (DrTS) in complex with the inhibitor Tris displayed an enclosed active site for catalysis of the intramoleular isomerization. In this study, the apo structure of the DrTS N253F mutant displays a new open conformation with an empty active site. Analysis of these structures suggests that substrate binding induces a domain rotation to close the active site. Such a substrate-induced domain rotation has also been observed in some other GH13 enzymes.

  9. Effects of Low-Temperature Plasma-Sterilization on Mars Analog Soil Samples Mixed with Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Janosch Schirmack

    2016-05-01

    Full Text Available We used Ar plasma-sterilization at a temperature below 80 °C to examine its effects on the viability of microorganisms when intermixed with tested soil. Due to a relatively low temperature, this method is not thought to affect the properties of a soil, particularly its organic component, to a significant degree. The method has previously been shown to work well on spacecraft parts. The selected microorganism for this test was Deinococcus radiodurans R1, which is known for its remarkable resistance to radiation effects. Our results showed a reduction in microbial counts after applying a low temperature plasma, but not to a degree suitable for a sterilization of the soil. Even an increase of the treatment duration from 1.5 to 45 min did not achieve satisfying results, but only resulted in in a mean cell reduction rate of 75% compared to the untreated control samples.

  10. The Deinococcus-Thermus phylum and the effect of rRNA composition on phylogenetic tree construction

    Science.gov (United States)

    Weisburg, W. G.; Giovannoni, S. J.; Woese, C. R.

    1989-01-01

    Through comparative analysis of 16S ribosomal RNA sequences, it can be shown that two seemingly dissimilar types of eubacteria Deinococcus and the ubiquitous hot spring organism Thermus are distantly but specifically related to one another. This confirms an earlier report based upon 16S rRNA oligonucleotide cataloging studies (Hensel et al., 1986). Their two lineages form a distinctive grouping within the eubacteria that deserved the taxonomic status of a phylum. The (partial) sequence of T. aquaticus rRNA appears relatively close to those of other thermophilic eubacteria. e.g. Thermotoga maritima and Thermomicrobium roseum. However, this closeness does not reflect a true evolutionary closeness; rather it is due to a "thermophilic convergence", the result of unusually high G+C composition in the rRNAs of thermophilic bacteria. Unless such compositional biases are taken into account, the branching order and root of phylogenetic trees can be incorrectly inferred.

  11. Effects of Low-Temperature Plasma-Sterilization on Mars Analog Soil Samples Mixed with Deinococcus radiodurans.

    Science.gov (United States)

    Schirmack, Janosch; Fiebrandt, Marcel; Stapelmann, Katharina; Schulze-Makuch, Dirk

    2016-05-26

    We used Ar plasma-sterilization at a temperature below 80 °C to examine its effects on the viability of microorganisms when intermixed with tested soil. Due to a relatively low temperature, this method is not thought to affect the properties of a soil, particularly its organic component, to a significant degree. The method has previously been shown to work well on spacecraft parts. The selected microorganism for this test was Deinococcus radiodurans R1, which is known for its remarkable resistance to radiation effects. Our results showed a reduction in microbial counts after applying a low temperature plasma, but not to a degree suitable for a sterilization of the soil. Even an increase of the treatment duration from 1.5 to 45 min did not achieve satisfying results, but only resulted in in a mean cell reduction rate of 75% compared to the untreated control samples.

  12. Effects of Low-Temperature Plasma-Sterilization on Mars Analog Soil Samples Mixed with Deinococcus radiodurans

    Science.gov (United States)

    Schirmack, Janosch; Fiebrandt, Marcel; Stapelmann, Katharina; Schulze-Makuch, Dirk

    2016-01-01

    We used Ar plasma-sterilization at a temperature below 80 °C to examine its effects on the viability of microorganisms when intermixed with tested soil. Due to a relatively low temperature, this method is not thought to affect the properties of a soil, particularly its organic component, to a significant degree. The method has previously been shown to work well on spacecraft parts. The selected microorganism for this test was Deinococcus radiodurans R1, which is known for its remarkable resistance to radiation effects. Our results showed a reduction in microbial counts after applying a low temperature plasma, but not to a degree suitable for a sterilization of the soil. Even an increase of the treatment duration from 1.5 to 45 min did not achieve satisfying results, but only resulted in in a mean cell reduction rate of 75% compared to the untreated control samples. PMID:27240407

  13. Biogeochemical inferences of mobility of early Holocene fisher-foragers from the Southern Sahara Desert.

    Science.gov (United States)

    Stojanowski, Christopher M; Knudson, Kelly J

    2011-09-01

    North Africa is increasingly seen as an important context for understanding modern human evolution and reconstructing biocultural adaptations. The Sahara, in particular, witnessed a fluorescence of hunter-gatherer settlement at the onset of the Holocene after an extended occupational hiatus. Subsequent subsistence changes through the Holocene are contrary to those documented in other areas where mobile foraging gave way to settled agricultural village life. In North Africa, extractive fishing and hunting was supplanted by cattle and caprine pastoralism under deteriorating climatic conditions. Therefore, the initial stage of food production in North Africa witnessed a likely increase in mobility. However, there are few studies of paleomobility in Early Holocene hunter-gatherer Saharan populations and the degree of mobility is generally assumed. Here, we present radiogenic strontium isotope ratios from Early Holocene fisher-forager peoples from the site of Gobero, central Niger, southern Sahara Desert. Data indicate a relatively homogeneous radiogenic strontium isotope signature for this hunter-gather population with limited variability exhibited throughout the life course or among different individuals. Although the overall signature was local, some variation in the radiogenic strontium isotope data likely reflects transhumance into the nearby Aïr Massif. Data from Gobero were significantly less variable than in other worldwide hunter-gatherer populations, including those thought to be fairly sedentary. Strontium data from Gobero were also significantly different from contemporaneous sites in southwestern Libya. These patterns are discussed with respect to archaeological models of community organization and technological evolution. 2011 Wiley-Liss, Inc.

  14. Were rivers flowing across the Sahara during the last interglacial? Implications for human migration through Africa.

    Directory of Open Access Journals (Sweden)

    Tom J Coulthard

    Full Text Available Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palaeo river systems could have been active at the key time of human migration across the Sahara. Unexpectedly, it is the most western of these three rivers, the Irharhar river, that represents the most likely route for human migration. The Irharhar river flows directly south to north, uniquely linking the mountain areas experiencing monsoon climates at these times to temperate Mediterranean environments where food and resources would have been abundant. The findings have major implications for our understanding of how humans migrated north through Africa, for the first time providing a quantitative perspective on the probabilities that these routes were viable for human habitation at these times.

  15. DETERMINANTS OF AGRICULTURAL PRODUCTIVITY GROWTH IN SUB-SAHARA AFRICA: 1961-2003

    Directory of Open Access Journals (Sweden)

    Olajide Abraham Ajao

    2012-12-01

    Full Text Available This study examined changes in agricultural productivity in Sub-Sahara Africa countries in the context of diverse institutional arrangements using Data Envelopment Analysis (DEA. From a time series which consists of information on agricultural production and means of production were obtained from FAO AGROSTAT and rainfall data from Steve O’Connell data base. The information was for a 43-year period (1961-2003; DEA method was used to measure Malmquist index of total factor productivity. A decomposition of TFP measures revealed that the observed increase in the TFP in the sub–Sahara Africa agriculture is due to technological change rather than efficiency change which is the main constrained of achieving higher level of TFP during the reference period. The study further examined the effect of land quality, malaria, education and selected governance indicators such as, control of corruption and government effectiveness on productivity growth. All the variables included in the model are significant with the exception of government effectiveness

  16. Geochemical variations in aeolian mineral particles from the Sahara-Sahel Dust Corridor.

    Science.gov (United States)

    Moreno, Teresa; Querol, Xavier; Castillo, Sonia; Alastuey, Andrés; Cuevas, Emilio; Herrmann, Ludger; Mounkaila, Mohammed; Elvira, Josep; Gibbons, Wes

    2006-10-01

    The Sahara-Sahel Dust Corridor runs from Chad to Mauritania and expels huge amounts of mineral aerosols into the Atlantic Ocean. Data on samples collected from Algeria, Chad, Niger, and Western Sahara illustrate how corridor dust mineralogy and chemistry relate to geological source and weathering/transport history. Dusts sourced directly from igneous and metamorphic massifs are geochemically immature, retaining soluble cations (e.g., K, Na, Rb, Sr) and accessory minerals containing HFSE (e.g., Zr, Hf, U, Th) and REE. In contrast, silicate dust chemistry in desert basins (e.g., Bodélé Depression) is influenced by a longer history of transport, physical winnowing (e.g., loss of Zr, Hf, Th), chemical leaching (e.g., loss of Na, K, Rb), and mixing with intrabasinal materials such as diatoms and evaporitic salts. Mineral aerosols blown along the corridor by the winter Harmattan winds mix these basinal and basement materials. Dusts blown into the corridor from sub-Saharan Africa during the summer monsoon source from deeply chemically weathered terrains and are therefore likely to be more kaolinitic and stripped of mobile elements (e.g., Na, K, Mg, Ca, LILE), but retain immobile and resistant elements (e.g., Zr, Hf, REE). Finally, dusts blown southwestwards into the corridor from along the Atlantic Coastal Basin will be enriched in carbonate from Mesozoic-Cenozoic marine limestones, depleted in Th, Nb, and Ta, and locally contaminated by uranium-bearing phosphate deposits.

  17. The Possible Interplanetary Transfer of Microbes: Assessing the Viability of Deinococcus spp. Under the ISS Environmental Conditions for Performing Exposure Experiments of Microbes in the Tanpopo Mission

    Science.gov (United States)

    Kawaguchi, Yuko; Yang, Yinjie; Kawashiri, Narutoshi; Shiraishi, Keisuke; Takasu, Masako; Narumi, Issay; Satoh, Katsuya; Hashimoto, Hirofumi; Nakagawa, Kazumichi; Tanigawa, Yoshiaki; Momoki, Yoh-hei; Tanabe, Maiko; Sugino, Tomohiro; Takahashi, Yuta; Shimizu, Yasuyuki; Yoshida, Satoshi; Kobayashi, Kensei; Yokobori, Shin-ichi; Yamagishi, Akihiko

    2013-10-01

    To investigate the possible interplanetary transfer of life, numerous exposure experiments have been carried out on various microbes in space since the 1960s. In the Tanpopo mission, we have proposed to carry out experiments on capture and space exposure of microbes at the Exposure Facility of the Japanese Experimental Module of the International Space Station (ISS). Microbial candidates for the exposure experiments in space include Deinococcus spp.: Deinococcus radiodurans, D. aerius and D. aetherius. In this paper, we have examined the survivability of Deinococcus spp. under the environmental conditions in ISS in orbit (i.e., long exposure to heavy-ion beams, temperature cycles, vacuum and UV irradiation). A One-year dose of heavy-ion beam irradiation did not affect the viability of Deinococcus spp. within the detection limit. Vacuum (10-1 Pa) also had little effect on the cell viability. Experiments to test the effects of changes in temperature from 80 °C to -80 °C in 90 min (±80 °C/90 min cycle) or from 60 °C to -60 °C in 90 min (±60 °C/90 min cycle) on cell viability revealed that the survival rate decreased severely by the ±80 °C/90 min temperature cycle. Exposure of various thicknesses of deinococcal cell aggregates to UV radiation (172 nm and 254 nm, respectively) revealed that a few hundred micrometer thick aggregate of deinococcal cells would be able to withstand the solar UV radiation on ISS for 1 year. We concluded that aggregated deinococcal cells will survive the yearlong exposure experiments. We propose that microbial cells can aggregate as an ark for the interplanetary transfer of microbes, and we named it `massapanspermia'.

  18. PprA Protein Is Involved in Chromosome Segregation via Its Physical and Functional Interaction with DNA Gyrase in Irradiated Deinococcus radiodurans Bacteria

    OpenAIRE

    Devigne, Alice; Guérin, Philippe; Lisboa, Johnny; Quevillon-Cheruel, Sophie; Armengaud, Jean; Sommer, Suzanne; Bouthier de la Tour, Claire; Servant, Pascale

    2016-01-01

    ABSTRACT PprA, a radiation-induced Deinococcus-specific protein, was previously shown to be required for cell survival and accurate chromosome segregation after exposure to ionizing radiation. Here, we used an in vivo approach to determine, by shotgun proteomics, putative PprA partners coimmunoprecipitating with PprA when cells were exposed to gamma rays. Among them, we found the two subunits of DNA gyrase and, thus, chose to focus our work on characterizing the activities of the deinococcal ...

  19. Long-distance autumn migration across the Sahara by painted lady butterflies: exploiting resource pulses in the tropical savannah.

    Science.gov (United States)

    Stefanescu, Constantí; Soto, David X; Talavera, Gerard; Vila, Roger; Hobson, Keith A

    2016-10-01

    The painted lady, Vanessa cardui, is a migratory butterfly that performs an annual multi-generational migration between Europe and North Africa. Its seasonal appearance south of the Sahara in autumn is well known and has led to the suggestion that it results from extremely long migratory flights by European butterflies to seasonally exploit the Sahel and the tropical savannah. However, this possibility has remained unproven. Here, we analyse the isotopic composition of butterflies from seven European and seven African countries to provide new support for this hypothesis. Each individual was assigned a geographical natal origin, based on its wing stable hydrogen isotope (δ 2 H w ) value and a predicted δ 2 H w basemap for Europe and northern Africa. Natal assignments of autumn migrants collected south of the Sahara confirmed long-distance movements (of 4000 km or more) starting in Europe. Samples from Maghreb revealed a mixed origin of migrants, with most individuals with a European origin, but others having originated in the Sahel. Therefore, autumn movements are not only directed to northwestern Africa, but also include southward and northward flights across the Sahara. Through this remarkable behaviour, the productive but highly seasonal region south of the Sahara is incorporated into the migratory circuit of V. cardui. © 2016 The Author(s).

  20. Adverse drug reaction reports for cardiometabolic drugs from sub Sahara Africa: A study in VigiBase

    NARCIS (Netherlands)

    Berhe, Derbew F.; Juhlin, Kristina; Star, Kristina; Haaijer-Ruskamp, Flora M.; Michael, Kidane; Taxis, Katja; Mol, Peter G. M.

    2014-01-01

    Background: Many pharmacovigilance centers have been established in Sub Sahara Africa (SSA) in recent years. Their focus has been on ADRs to drugs for communicable diseases. Little is known about ADRs caused by drugs for cardiometabolic diseases, although its burden is increasing rapidly in SSA.

  1. Declines in a ground-dwelling arthropod community during an invasion by Sahara mustard (Brassica tournefortii) in aeolian sand habitats

    Science.gov (United States)

    Heather L. Hulton VanTassel; Anne M. Hansen; Cameron W. Barrows; Quresh Latif; Margaret W. Simon; Kurt E. Anderson

    2014-01-01

    Sahara Mustard (Brassica tournefortii; hereafter mustard), an exotic plant species, has invaded habitats throughout the arid southwestern United States. Mustard has reached high densities across aeolian sand habitats of southwestern deserts, including five distinct sand habitats in the eastern Coachella Valley, California. We examined trends in ground-dwelling...

  2. Complex oligomeric structure of a truncated form of DdrA: A protein required for the extreme radio-tolerance of Deinococcus

    Energy Technology Data Exchange (ETDEWEB)

    Gutsche, I. [CNRS-EMBL-Univ Grenoble 1, Unit Virus Host Cell Interact UMR5233, F-38042 Grenoble (France); Vujicic-Zagar, A.; Serre, L. [CEA-CNRS-Univ Grenoble 1, Inst Biol Struct, UMR5075, Lab Prot Membranaires, F-38027 Grenoble 01 (France); Siebert, X. [CEA-CNRS-Univ Grenoble 1, Inst Biol Struct UMR5075, Lab Microscopie Elect et struct, F-38027 Grenoble 01 (France); Servant, P.; Vannier, F.; Sommer, S. [Univ Paris 11, CNRS UMR 8621, CEA LRC42V, Inst Genet et Microbiol, F-91405 Orsay (France); Castaing, B. [CNRS, UMR4301, Ctr Biophys Mol, F-45071 Orleans 02 (France); Gallet, B. [CEA-CNRS-Univ Grenoble 1, Inst Biol Struct UMR 5075, ROBIOMOL, Lab Ingn Macrom, F-38027 Grenoble 01 (France); Heulin, T.; De Groot, A. [CEA, DSV, IBEB, SBVME, Lab Ecol Microbienne Rhizosphere et Environm Extre, UMR 6191, F-13108 St Paul Les Durance (France)

    2008-07-01

    In order to preserve their genome integrity, organisms have developed elaborate tactics for genome protection and repair. The Deinococcus radiodurans bacteria famous for their extraordinary tolerance toward high doses of radiations or long period of desiccation, possess some specific genes with unknown function which are related to their survival in such extreme conditions. Among them, ddrA is an orphan gene specific of Deinococcus genomes. DdrA, the product of this gene was suggested to be a component of the DNA end protection system. Here we provide a three-dimensional reconstruction of the Deinococcus deserti DdrA(1-160) by electron microscopy. Although not functional in vivo, this truncated protein keeps its DNA binding ability at the wild-type level. DdrA(1-160) has a complex three-dimensional structure based on a hepta-meric ring that can self-associate to form a larger molecular weight assembly. We suggest that the complex architecture of DdrA plays a role in the substrate specificity and favors an efficient DNA repair. (authors)

  3. DrwH, a novel WHy domain-containing hydrophobic LEA5C protein from Deinococcus radiodurans, protects enzymatic activity under oxidative stress.

    Science.gov (United States)

    Jiang, Shijie; Wang, Jin; Liu, Xiaoli; Liu, Yingying; Guo, Cui; Zhang, Liwen; Han, Jiahui; Wu, Xiaoli; Xue, Dong; Gomaa, Ahmed E; Feng, Shuai; Zhang, Heng; Chen, Yun; Ping, Shuzhen; Chen, Ming; Zhang, Wei; Li, Liang; Zhou, Zhengfu; Zuo, Kaijing; Li, Xufeng; Yang, Yi; Lin, Min

    2017-08-24

    Water stress and hypersensitive response (WHy) domain is typically found as a component of atypical late embryogenesis abundant (LEA) proteins closely associated with resistance to multiple stresses in numerous organisms. Several putative LEA proteins have been identified in Deinococcus bacteria; however their precise function remains unclear. This work reports the characterization of a Deinococcus-specific gene encoding a novel WHy domain-containing hydrophobic LEA5C protein (named DrwH) in D. radiodurans R1. The expression of the drwH gene was induced by oxidative and salinity stresses. Inactivation of this gene resulted in increased sensitivity to oxidative and salinity stresses as well as reduced activities of antioxidant enzymes. The WHy domain of the DrwH protein differs structurally from that of a previously studied bacterial LEA5C protein, dWHy1, identified as a gene product from an Antarctic desert soil metagenome library. Further analysis indicated that in E. coli, the function of DrwH is related to oxidative stress tolerance, whereas dWHy1 is associated with freezing-thawing stress tolerance. Under oxidative stress induced by H2O2, DrwH protected the enzymatic activities of malate dehydrogenase (MDH) and lactate dehydrogenase (LDH). These findings provide new insight into the evolutionary and survival strategies of Deinococcus bacteria under extreme environmental conditions.

  4. Groundwater resources exploration in the Zug area (Tiris, Western Sahara); Prospeccion de recursos hidricos subterraneos en el area de Zug (Tiris, Sahara Occidental)

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, B.; Villarroya, F.; Rebollo, L. F.; Olaiz, A.; Lopez, J.

    2015-07-01

    The area of Zug is located in the southwestern corner of the Tiris dorsal, in the Western Sahara. The area is characterized by outcrops of materials, mainly gneisses of archaic age and fractured granitic rocks, which in the southern sector are covered by aeolian sand sheets. A hydrogeological survey of the territory has been carried out, and boreholes and dug wells have been located and analyzed and this information integrated with the sparse outcrops. Based on this study, two hydrogeological domains have been established: Zug and Azzefal. From the analysis of satellite images, field work, geophysical profiles, a well inventory and chemical analysis, three priority areas for the location of future water supply wells have been identified: 1) alluvial fans, preferably located on the slopes of the dikes that cross the Tiris dorsal; 2) sabkhas (salt flats) as places of con- centration of ephemeral runoff and subsurface infiltration of accumulated water; 3) highly fractured granitic areas. Some of these three cases coincide with existing wells in this area. Electrical tomography shows how, in specific locations, low resistivity values reach 50 metres, opening up the possibility of finding sufficient water to meet the aforementioned needs. The water quality is not suitable for human supply directly from the well without chemical treatment. The area is still full of opportunities for future research, but only when a more stable political situation exists. (Author)

  5. Regional hydrogen roadmap. Project development framework for the Sahara Wind Project

    Energy Technology Data Exchange (ETDEWEB)

    Benhamou, Khalid [Sahara Wind Inc., Rabat (Morocco); Arbaoui, Abdelaziz [Ecole National Superieure des Arts et Metiers ENSAM Meknes (Morocco); Loudiyi, Khalid [Al Akhawayn Univ. (Morocco); Ould Mustapha, Sidi Mohamed [Nouakchott Univ. (Mauritania). Faculte des Sciences et Techniques

    2010-07-01

    The trade winds that blow along the Atlantic coast from Morocco to Senegal represent one of the the largest and most productive wind potentials available on earth. Because of the erratic nature of winds however, wind electricity cannot be integrated locally on any significant scale, unless mechanisms are developed for storing these intermittent renewable energies. Developing distributed wind energy solutions feeding into smaller electricity markets are essential for solving energy access issues and enabling the development of a local, viable renewable energy industry. These may be critical to address the region's economic challenges currently under pressure from Sub-Saharan migrant populations. Windelectrolysis for the production of hydrogen can be used in grid stabilization, as power storage, fuel or chemical feedstock in specific industries. The objective of the NATO SfP 'Sahara Trade Winds to Hydrogen' project is to support the region's universities through an applied research framework in partnership with industries where electrolysis applications are relevant. By powering two university campuses in Morocco and Mauritania with small grid connected wind turbines and 30 kW electrolyzers generating hydrogen for power back-up as part of ''green campus concepts'' we demonstrated that wind-electrolysis for the production of hydrogen could absorb larger quantities of cheap generated wind electricity in order to maximize renewable energy uptakes within the regions weaker grid infrastructures. Creating synergies with local industries to tap into a widely available renewable energy source opens new possibilities for end users such as utilities or mining industries when processing raw minerals, whose exports generates key incomes in regions most exposed to desertification and climate change issue. Initiated by Sahara Wind Inc. a company from the private sector, along with the Al Akhawayn University, the Ecole Nationale Superieure

  6. Dune ages in the sand deserts of the southern Sahara and Sahel

    Science.gov (United States)

    Bristow, Charlie; Armitage, Simon

    2015-04-01

    In this paper we aim to document the history of aeolian processes within the southern Sahara as part of the INQUA Dune Atlas. We review available luminescence ages for sand dunes across the southern Sahara and attempt to correlate periods of sand accumulation and to develop an improved understanding of the dune chronology on a regional basis. This was achieved by analysing dune age by country, as well as by latitude and longitude. The results show a very patchy spatial distribution of dune ages with large gaps that encompass some of the largest sand seas. Despite these gaps, some related patterns in dune morphology and stratigraphy appear to be consistent between northern Nigeria and southern Mali where older linear dunes are distinct from younger Late Holocene transverse and barchanoid dunes. Elsewhere in Mauretania linear dunes with different orientations appear to have accumulated at different times, most likely in response to changes in atmospheric circulation. Regional climatic changes are identified where dunes are transgressed by lake deposits within endorehic basins. We identify four locations where dune accumulation is terminated by lacustrine transgressions, two of which, in Lake Chad and the Bodélé Depression, occur shortly after the last glacial maximum (LGM). The third example at Gobiero in Niger occurred later, in the early Holocene, around 8.4 ka and a fourth marks a later transgression of Palaeolake MegaChad after 4.7 ka. Larger-scale latitudinal and longitudinal distributions in dune ages across the southern Sahara do not show any consistent patterns, though this may due to the small sample size relative to the study area. In addition, local variations in external controls such as wind regime, rainfall, vegetation and sand supply need to be considered, sometimes on a site by site basis. Limiting the analysis to dune ages determined using the single-aliquot regenerative-dose (SAR) protocol indicates a lack of dune preservation during the LGM and

  7. Shock Metamorphism of L6 Chondrites Sahara 98222 and Yamato 74445: the P-T Conditions and the Shock age

    Science.gov (United States)

    Ozawa, S.; Ohtani, E.; Suzuki, A.; Miyahara, M.; Terada, K.; Kimura, M.

    2007-12-01

    Impact phenomena are the fundamental processes of accretion of the terrestrial planets. Therefore, investigations of meteorites that experienced shock events are useful for understanding mechanisms of planetary impact events and formation of terrestrial planets. Heavily shocked meteorites contain abundant shock melt veins, where some high-pressure minerals have been discovered. In this study, we investigated mineralogy of shock melt veins of two L6 chondrites (Sahara 98222 and Yamato 74445) and estimated the P-T conditions during their impact events.We found that the shock melt veins of these meteorites contain several high-pressure minerals such as wadsleyite, jadeite and tuite for Sahara 98222 and ringwoodite (+ wadsleyite), akimotoite and lingunite for Yamato 74445. Tuite is a high-pressure polymorph of whitlockite and lingunite is a high-pressure polymorph of albite with hollandite structure. Based on mineralogy in the shock veins; we estimated the pressure and temperature conditions during their impact events: 13-15 GPa, > 2000°C for Sahara 98222 and 15- 24 GPa, > 2200°C for Yamato 74445, respectively.We also conducted a U-Pb dating of phosphates in and around the shock melt veins of Sahara 98222 using a Sensitive High Resolution Ion Micro Probe (SHRIMP-II) at Hiroshima University to reveal when this shock event occurred. We obtained following radioactive ages: Pb-Pb isochron age: 4466 ± 31 Ma; U-Pb isochron age: 4498 ± 150 Ma; Total U-Pb isochron age: 4467 ± 22 Ma. These ages seem to be slightly younger than the previously reported ages of chondrites, which are usually older than 4500 Ma. This could suggest that Sahara 98222 have recorded a shock event in the very early stage of the solar system where the planetary formation was going on.

  8. Local Human Development in contexts of permanent crisis: Women’s experiences in the Western Sahara

    Directory of Open Access Journals (Sweden)

    María López Belloso

    2009-04-01

    Full Text Available Sahrawi women are active agents in the social dynamics of the refugee camps, in which they have developeda number of coping strategies to overcome the hardships of a deteriorating humanitarian situation. Since the outbreak of the con#ict and the forced settlement in Tindouf, Algeria, women have been responsible for the entire management of refugee camps, assuming leadership roles in many sectors of society.This paper highlights the Sahrawi women’s contribution to the process of local human development in a context of protracted refuge such as the one in the Western Sahara. In addition to the enlargement of the refugee population’s capacities in relation to material and physical assets, social and organizational abilities, and motivational strengths, one of the major achievements of Sahrawi women has been their own individual and collective process of empowerment within the camp life.

  9. Comparison of efficacy of unheated and heat-treated Sahara honey on wound healing in rabbits

    Directory of Open Access Journals (Sweden)

    Baghdad Khiati

    2015-02-01

    Full Text Available Objective: To investigate the efficacy of unheated and heat-treated Sahara honey on wound healing in rabbits on the basis of macroscopic observation changes. Methods: Eight female rabbits were used. Using aseptic surgical technique, a 3 cm incision was made on the back of each rabbit and two rabbits with injuries in each group were treated daily with a topical application of unheated and heated honey, sulfadiazine and sterile saline, respectively. Results: The unheated honey demonstrated the highest activity on the wound compared to reference ointment silver sulfadiazine, heat-treated honey and sterile saline respectively. Further the present investigation proves that unheated honey is possessing superior wound healing activity than that of heat-treated honey. Conclusions: The result of this study confirms that unheated honey had the best wound healing effect even better than heat-treated honey.

  10. δ13C values of grass species collected in the northern Sahara desert.

    Science.gov (United States)

    Winter, Klaus; Troughton, John H; Card, Kay A

    1976-06-01

    δ13C values were measured for 45 Poaceae species collected in the northern Sahara desert, at the foot of the Saharan Atlas. The results indicate a clear relationship between carbon isotope discrimination and phytogeographical distribution of the grasses. Mediterranean species predominantly had δ13C values indicating the C3 pathway of photosynthesis. By contrast, nearly all species belonging to the Saharo-Arabian and /or Sudanian group showed a C4 like carbon isotope composition. Leaf material of two species, Lygeum spartum and Stipa tenacissima, had δ13C values in the region of-20‰, i.e. intermediate between the mean δ13C values of C3 and C4 plants. However, additional speciments of both these grasses obtained from a different source (herbarium of the Hebrew University, Jerusalem) yielded a C3 like carbon isotope composition.

  11. Greening of the Sahara suppressed ENSO activity during the mid-Holocene

    Science.gov (United States)

    Pausata, Francesco S. R.; Zhang, Qiong; Muschitiello, Francesco; Lu, Zhengyao; Chafik, Léon; Niedermeyer, Eva M.; Stager, J. Curt; Cobb, Kim M.; Liu, Zhengyu

    2017-07-01

    The evolution of the El Niño-Southern Oscillation (ENSO) during the Holocene remains uncertain. In particular, a host of new paleoclimate records suggest that ENSO internal variability or other external forcings may have dwarfed the fairly modest ENSO response to precessional insolation changes simulated in climate models. Here, using fully coupled ocean-atmosphere model simulations, we show that accounting for a vegetated and less dusty Sahara during the mid-Holocene relative to preindustrial climate can reduce ENSO variability by 25%, more than twice the decrease obtained using orbital forcing alone. We identify changes in tropical Atlantic mean state and variability caused by the momentous strengthening of the West Africa Monsoon (WAM) as critical factors in amplifying ENSO's response to insolation forcing through changes in the Walker circulation. Our results thus suggest that potential changes in the WAM due to anthropogenic warming may influence ENSO variability in the future as well.

  12. Dust and Biological Aerosols from the Sahara and Asia Influence Precipitation in the Western US

    Energy Technology Data Exchange (ETDEWEB)

    Creamean, Jessie; Suski, Kaitlyn; Rosenfeld, Daniel; Cazorla, Alberto; DeMott, Paul J.; Sullivan, Ryan C.; White, Allen B.; Ralph, F. M.; Minnis, Patrick; Comstock, Jennifer M.; Tomlinson, Jason M.; Prather, Kimberly

    2013-03-29

    Winter storms in California’s Sierra Nevada increase seasonal snowpack and provide critical water resources for the state. Thus, the mechanisms influencing precipitation in this region have been the subject of research for decades. Previous studies suggest Asian dust enhances cloud ice and precipitation (1), while few studies consider biological aerosols as an important global source of ice nuclei (IN). Here, we show that dust and biological aerosols transported from as far as the Sahara were present in glaciated high-altitude clouds coincident with elevated IN concentrations and ice-induced precipitation. This study presents the first direct cloud and precipitation measurements showing that Saharan and Asian dust and biological aerosols likely serve as IN and play an important role in orographic precipitation processes over the western United States.

  13. Surface features on Sahara soil dust particles made visible by atomic force microscope (AFM phase images

    Directory of Open Access Journals (Sweden)

    M. O. Andreae

    2008-10-01

    Full Text Available We show that atomic force microscopy (AFM phase images can reveal surface features of soil dust particles, which are not evident using other microscopic methods. The non-contact AFM method is able to resolve topographical structures in the nanometer range as well as to uncover repulsive atomic forces and attractive van der Waals' forces, and thus gives insight to surface properties. Though the method does not allow quantitative assignment in terms of chemical compound description, it clearly shows deposits of distinguishable material on the surface. We apply this technique to dust aerosol particles from the Sahara collected over the Atlantic Ocean and describe micro-features on the surfaces of such particles.

  14. Global Sea Level Stabilization-Sand Dune Fixation: A Solar-powered Sahara Seawater Textile Pipeline

    CERN Document Server

    Badescu, Viorel; Bolonkin, Alexander A

    2007-01-01

    Could anthropogenic saturation with pumped seawater of the porous ground of active sand dune fields in major deserts (e.g., the westernmost Sahara) cause a beneficial reduction of global sea level? Seawater extraction from the ocean, and its deposition on deserted sand dune fields in Mauritania and elsewhere via a Solar-powered Seawater Textile Pipeline (SSTP) can thwart the postulated future global sea level. Thus, Macro-engineering offers an additional cure for anticipated coastal change, driven by global sea level rise, that could supplement, or substitute for (1) stabilizing the shoreline with costly defensive public works (armoring macroprojects) and (2) permanent retreat from the existing shoreline (real and capital property abandonment). We propose Macro-engineering use tactical technologies that sculpt and vegetate barren near-coast sand dune fields with seawater, seawater that would otherwise, as commonly postulated, enlarge Earth seascape area! Our Macro-engineering speculation blends eremology with...

  15. Tuberculosis in African refugees from the Eastern Sub-Sahara region.

    Science.gov (United States)

    Nesher, Lior; Riesenberg, Klaris; Saidel-Odes, Lisa; Schlaeffer, Francisc; Smolyakov, Rorzalia

    2012-02-01

    The southern region of Israel has recently experienced an influx of African refugees from the Eastern Sub-Sahara desert area. These influxes have led to a significant increase in incidence of tuberculosis (TB) in that region. To review the data of African refugees diagnosed with TB between January 2008 and August 2010 at a tertiary care regional hospital. Twenty-five TB cases were diagnosed, 22 of which presented with pulmonary TB, 3 with extra-pulmonary TB (EPTB), and 7 with combined pulmonary and EPTB. Only one case had concomitant human immunodeficiency virus (HIV) infection and multidrug-resistant TB. Fifteen patients underwent extensive radiological investigations including chest, abdominal and spine computed tomography, 1 was reviewed by magnetic resonance imaging, and 9 underwent tissue biopsy. Eighteen patients were admitted as suspected TB and 4 as suspected pneumonia or pulmonary infiltrates that could have been defined as suspected TB. All 24 HIV-negative cases were sensitive to first-line drugs for TB, except for one case that was resistant to streptomycin and one to rifampicin. All patients responded well to first-line therapy. The average duration of hospitalization was 8.7 days (range 1-36). Following diagnosis 23 patients were transferred to a quarantine facility. We identified overutilization of medical resources and invasive procedures. For African refugees from the eastern Sub-Sahara who were HIV-negative and suspected of having TB, a sputum acid-fast smear and culture should have been the primary investigative tools before initiating treatment with four drugs (first-line), and further investigations should have been postponed and reserved for non-responders or for patients for whom the culture was negative. Physicians should maintain a high index of suspicion for EPTB in this population.

  16. Inside the "African cattle complex": animal burials in the holocene central Sahara.

    Directory of Open Access Journals (Sweden)

    Savino di Lernia

    Full Text Available Cattle pastoralism is an important trait of African cultures. Ethnographic studies describe the central role played by domestic cattle within many societies, highlighting its social and ideological value well beyond its mere function as 'walking larder'. Historical depth of this African legacy has been repeatedly assessed in an archaeological perspective, mostly emphasizing a continental vision. Nevertheless, in-depth site-specific studies, with a few exceptions, are lacking. Despite the long tradition of a multi-disciplinary approach to the analysis of pastoral systems in Africa, rarely do early and middle Holocene archaeological contexts feature in the same area the combination of settlement, ceremonial and rock art features so as to be multi-dimensionally explored: the Messak plateau in the Libyan central Sahara represents an outstanding exception. Known for its rich Pleistocene occupation and abundant Holocene rock art, the region, through our research, has also shown to preserve the material evidence of a complex ritual dated to the Middle Pastoral (6080-5120 BP or 5200-3800 BC. This was centred on the frequent deposition in stone monuments of disarticulated animal remains, mostly cattle. Animal burials are known also from other African contexts, but regional extent of the phenomenon, state of preservation of monuments, and associated rock art make the Messak case unique. GIS analysis, excavation data, radiocarbon dating, zooarchaeological and isotopic (Sr, C, O analyses of animal remains, and botanical information are used to explore this highly formalized ritual and the lifeways of a pastoral community in the Holocene Sahara.

  17. Characterization of a new feather-degrading bacterium from Calotes ...

    African Journals Online (AJOL)

    A total of 842 spore-forming strains were isolated from 221 animal feces samples, in which a new feather-degrading bacterium identified as Bacillus sp. 50-3 based on morphological, biochemical and 16S rDNA tests was isolated from Calotes versicolor (an agamid lizard) feces. The bacterium can degrade native feather ...

  18. Screening and characterization of petroleum-degrading bacterium ...

    African Journals Online (AJOL)

    ... in 250 ml flask, shaking at 150 r/min and 32°C, petroleum-degrading rate was 75 to 77%. The petroleum-degrading bacterium might be a useful resource for bioremediation of oil-contaminated soils and biotreatment of oil wastewater. Key words: Petroleum-degrading bacterium, screening, Bacillus cereus, bioremediation.

  19. Deinococcus radiodurans RecA nucleoprotein filaments characterized at the single-molecule level with optical tweezers

    Energy Technology Data Exchange (ETDEWEB)

    Pobegalov, Georgii, E-mail: george.pobegalov@nanobio.spbstu.ru [Peter the Great St.Petersburg Polytechnic University, Saint-Petersburg 195251 (Russian Federation); Cherevatenko, Galina; Alekseev, Aleksandr; Sabantsev, Anton; Kovaleva, Oksana; Vedyaykin, Alexey; Morozova, Natalia [Peter the Great St.Petersburg Polytechnic University, Saint-Petersburg 195251 (Russian Federation); Baitin, Dmitrii [Peter the Great St.Petersburg Polytechnic University, Saint-Petersburg 195251 (Russian Federation); Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina 188300 (Russian Federation); Khodorkovskii, Mikhail [Peter the Great St.Petersburg Polytechnic University, Saint-Petersburg 195251 (Russian Federation)

    2015-10-23

    Deinococcus radiodurans can survive extreme doses of ionizing radiation due to the very efficient DNA repair mechanisms that are able to cope even with hundreds of double-strand breaks. RecA, the critical protein of homologous recombination in bacteria, is one of the key components of the DNA-repair system. Repair of double-strand breaks requires RecA binding to DNA and assembly of the RecA nucleoprotein helical filaments. The Escherichia coli RecA protein (EcRecA) and its interactions with DNA have been extensively studied using various approaches including single-molecule techniques, while the D. radiodurans RecA (DrRecA) remains much less characterized. However, DrRecA shows some remarkable differences from E. coli homolog. Here we combine microfluidics and single-molecule DNA manipulation with optical tweezers to follow the binding of DrRecA to long double-stranded DNA molecules and probe the mechanical properties of DrRecA nucleoprotein filaments at physiological pH. Our data provide a direct comparison of DrRecA and EcRecA binding to double-stranded DNA under identical conditions. We report a significantly faster filaments assembly as well as lower values of persistence length and contour length for DrRecA nucleoprotein filaments compared to EcRecA. Our results support the existing model of DrRecA forming more frequent and less continuous filaments relative to those of EcRecA. - Highlights: • We investigate Deinococcus radiodurans RecA interactions with long double-stranded DNA at the single-molecule level. • At physiological pH D. radiodurans RecA forms nucleoprotein filaments significantly faster relative to Escherichia coli RecA. • D. radiodurans RecA-dsDNA nucleoprotein filaments are more flexible and slightly shorter compared to those of E. coli RecA.

  20. A study of the relict fish fauna of northern Chad, with the first records of a polypterid and a poeciliid in the Sahara desert

    OpenAIRE

    Trape, Sébastien

    2013-01-01

    Seventeen species and sub-species of fishes belonging to four families (Cyprinidae, Clariidae, Aplocheilidae, Cichlidae) were known to occur in perennial bodies of water in the Sahara desert. The study of fishes collected in Lake Boukou near Ounianga Serir (Borkou, northern Chad) shows, for the first time, the occurrence in the Sahara desert of relict populations of Polypterus senegalus (Polypteridae) and Poropanchax normani (Poeciliidae). The Cichlidae Tilapia zilli was also collected in thi...

  1. Monitoring project impact on biomass increase in the context of the Great Green Wall for the Sahara and Sahel Initiative in Senegal

    OpenAIRE

    SCHUCKNECHT ANNE; MERONI MICHELE; REMBOLD Felix

    2016-01-01

    Land degradation and desertification represent a major threat to the population and ecosystems of (semi)-arid regions like the Sahel and the Sahara. In 2007, the African Union launched a pan-African programme, the Great Green Wall for the Sahara and the Sahel Initiative (GGWSSI) to reverse land degradation and desertification in the region, improve food security and support local people to adapt to climate change. Within the GGWSSI different kinds of projects have been implemented. In order t...

  2. Comparative survival analysis of 12 histidine kinase mutants of Deinococcus radiodurans after exposure to DNA-damaging agents.

    Science.gov (United States)

    Im, Seonghun; Song, Dusup; Joe, Minho; Kim, Dongho; Park, Don-Hee; Lim, Sangyong

    2013-06-01

    Bacteria are able to adapt to changes in the environment using two-component signal transduction systems (TCSs) composed of a histidine kinase (HK) and a response regulator (RR). Deinococcus radiodurans, one of the most resistant organisms to ionizing radiation, has 20 putative HKs and 25 putative RRs. In this study, we constructed 12 D. radiodurans mutant strains lacking a gene encoding a HK and surveyed their resistance to γ-radiation, UV-B radiation (302 nm), mitomycin C (MMC), and H(2)O(2). Five (dr0860 (-), dr1174 (-), dr1556 (-), dr2244 (-), and dr2419 (-)) of the 12 mutant strains showed at least a one-log cycle reduction in γ-radiation resistance. The mutations (1) dr1174, dr1227, and dr2244 and (2) dr0860, dr2416, and dr2419 caused decreases in resistance to UV radiation and MMC, respectively. Only the dr2416 and dr2419 mutant strains showed higher sensitivity to H(2)O(2) than the wild-type. Reductions in the resistance to γ-radiation and H(2)O(2), but not to UV and MMC, were observed in the absence of DR2415, which seems to be a cognate RR of DR2416. This result suggests that DR2415/DR2416 (DrtR/S: DNA damage response TCS) may be another TCS responsible for the extreme resistance of D. radiodurans to DNA-damaging agents.

  3. A tamB homolog is involved in maintenance of cell envelope integrity and stress resistance of Deinococcus radiodurans

    Science.gov (United States)

    Yu, Jiangliu; Li, Tao; Dai, Shang; Weng, Yulan; Li, Jiulong; Li, Qinghao; Xu, Hong; Hua, Yuejin; Tian, Bing

    2017-01-01

    The translocation and assembly module (TAM) in bacteria consists of TamA and TamB that form a complex to control the transport and secretion of outer membrane proteins. Herein, we demonstrated that the DR_1462-DR_1461-DR_1460 gene loci on chromosome 1 of Deinococcus radiodurans, which lacks tamA homologs, is a tamB homolog (DR_146T) with two tamB motifs and a DUF490 motif. Mutation of DR_146T resulted in cell envelope peeling and a decrease in resistance to shear stress and osmotic pressure, as well as an increase in oxidative stress resistance, consistent with the phenotype of a surface layer (S-layer) protein SlpA (DR_2577) mutant, demonstrating the involvement of DR_146T in maintenance of cell envelope integrity. The 123 kDa SlpA was absent and only its fragments were present in the cell envelope of DR_146T mutant, suggesting that DR_146T might be involved in maintenance of the S-layer. A mutant lacking the DUF490 motif displayed only a slight alteration in phenotype compared with the wild type, suggesting DUF490 is less important than tamB motif for the function of DR_146T. These findings enhance our understanding of the properties of the multilayered envelope in extremophilic D. radiodurans, as well as the diversity and functions of TAMs in bacteria. PMID:28383523

  4. Involvement of recF in 254 nm ultraviolet radiation resistance in Deinococcus radiodurans and Escherichia coli.

    Science.gov (United States)

    Chang, Xiaosong; Yang, Lan; Zhao, Qing; Fu, Wenjuan; Chen, Hao; Qiu, Zhiqun; Chen, Ji-an; Hu, Ran; Shu, Weiqun

    2010-11-01

    recF is a critical gene involved in the RecFOR pathway of DNA repair in Deinococcus radiodurans (D. radiodurans). To investigate the role of recF in UV-C radiation resistance, we generated the recF-deficient D. radiodurans strain R1, expressed recF in Escherichia coli (E. coli) BL21 cells, and compared the ability of each to resist UV-C radiation by F (10), inactivation constant (IC), and extrapolation number (N). The mutation of recF in D. radiodurans R1 resulted in characteristic slow growth and dramatic sensitivity to UV-C irradiation. Transformation of recF into E. coli BL21 cells resulted in increased UV-C resistance compared to untransformed E. coli BL21 cells. These results suggested that recF is needed for the replication of D. radiodurans. Furthermore, as a part of the RecFOR pathway in D. radiodurans, disruption of recF could dramatically decrease the UV-C resistance of D. radiodurans and recF could increase the UV-C resistance of E. coli BL21 cells.

  5. Purification, crystallization and preliminary crystallographic analysis of DR0248, an MNT-HEPN fused protein from Deinococcus radiodurans.

    Science.gov (United States)

    Pesce, Gaelle; Pellegrino, Simone; McSweeney, Sean; Goncalves, AnaMaria; de Sanctis, Daniele

    2015-01-01

    DR0248 is a protein identified in the Deinococcus radiodurans (DR) genome that is predicted to encompass two domains: an N-terminal minimal nucleotidyl transferase domain (MNT) and a C-terminal higher eukaryotes and prokaryotes nucleotide-binding domain (HEPN). These two domains, usually encoded in two ORFs, have been suggested to play the role of a toxin-antitoxin (TA) system in prokaryotes. Recombinant DR0248 was overexpressed and purified from Escherichia coli and diffraction-quality crystals were obtained in the presence of the detergent molecules dodecyldimethylamine oxide (DDAO) and octaethylene glycol monododecyl ether (C12E8), which were used as crystallization additives. Crystals grown with DDAO diffracted to a resolution of 2.24 Å and belonged to space group C222(1), with unit-cell parameters a=98.4, b=129.9, c=59.2 Å. Crystals grown with C12E8 diffracted to a resolution of 1.83 Å and belonged to space group P2(1)2(1)2(1), with unit-cell parameters a=51.6, b=87.2, c=108.2 Å. The structure was solved by multiwavelength anomalous dispersion from zinc bound to the protein using a single crystal obtained in the presence of DDAO.

  6. The key residue for SSB-RecO interaction is dispensable for Deinococcus radiodurans DNA repair in vivo.

    Science.gov (United States)

    Cheng, Kaiying; Xu, Xin; Zhao, Ye; Wang, Liangyan; Xu, Guangzhi; Hua, Yuejin

    2014-05-01

    The RecFOR DNA repair pathway is one of the major RecA-dependent recombinatorial repair pathways in bacteria and plays an important role in double-strand breaks repair. RecO, one of the major recombination mediator proteins in the RecFOR pathway, has been shown to assist RecA loading onto single-stranded binding protein (SSB) coated single-stranded DNA (ssDNA). However, it has not been characterized whether the protein-protein interaction between RecO and SSB contributes to that process in vivo. Here, we identified the residue arginine-121 of Deinococcus radiodurans RecO (drRecO-R121) as the key residue for RecO-SSB interaction. The substitution of drRecO-R121 with alanine greatly abolished the binding of RecO to SSB but not the binding to RecR. Meanwhile, SSB-coated ssDNA annealing activity was also compromised by the mutation of the residue of drRecO. However, the drRecO-R121A strain showed only modest sensitivity to DNA damaging agents. Taking these data together, arginine-121 of drRecO is the key residue for SSB-RecO interaction, which may not play a vital role in the SSB displacement and RecA loading process of RecFOR DNA repair pathway in vivo.

  7. Identification of new genes contributing to the extreme radioresistance of Deinococcus radiodurans using a Tn5-based transposon mutant library.

    Science.gov (United States)

    Dulermo, Rémi; Onodera, Takefumi; Coste, Geneviève; Passot, Fanny; Dutertre, Murielle; Porteron, Martine; Confalonieri, Fabrice; Sommer, Suzanne; Pasternak, Cécile

    2015-01-01

    Here, we have developed an extremely efficient in vivo Tn5-based mutagenesis procedure to construct a Deinococcus radiodurans insertion mutant library subsequently screened for sensitivity to genotoxic agents such as γ and UV radiations or mitomycin C. The genes inactivated in radiosensitive mutants belong to various functional categories, including DNA repair functions, stress responses, signal transduction, membrane transport, several metabolic pathways, and genes of unknown function. Interestingly, preliminary characterization of previously undescribed radiosensitive mutants suggests the contribution of cyclic di-AMP signaling in the recovery of D. radiodurans cells from genotoxic stresses, probably by modulating several pathways involved in the overall cell response. Our analyses also point out a new transcriptional regulator belonging to the GntR family, encoded by DR0265, and a predicted RNase belonging to the newly described Y family, both contributing to the extreme radioresistance of D. radiodurans. Altogether, this work has revealed new cell responses involved either directly or indirectly in repair of various cell damage and confirmed that D. radiodurans extreme radiation resistance is determined by a multiplicity of pathways acting as a complex network.

  8. Synthesis and extracellular accumulation of silver nanoparticles by employing radiation-resistant Deinococcus radiodurans, their characterization, and determination of bioactivity.

    Science.gov (United States)

    Kulkarni, Rasika R; Shaiwale, Nayana S; Deobagkar, Dileep N; Deobagkar, Deepti D

    2015-01-01

    There has been rapid progress in exploring microorganisms for green synthesis of nanoparticles since microbes show extraordinary diversity in terms of species richness and niche localization. Microorganisms are easy to culture using relatively inexpensive and simple nutrients under varied conditions of temperature, pressure, pH, etc. In this work, Deinococcus radiodurans that possesses the ability to withstand extremely high radiation and desiccation stress has been employed for the synthesis of silver nanoparticles (AgNPs). D. radiodurans was able to accumulate AgNPs in medium under various conditions, and process optimization was carried out with respect to time, temperature, pH, and concentration of silver salt. AgNPs were characterized using UV/vis spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The microbially synthesized AgNPs exhibited good antimicrobial activity against both Gram-negative and Gram-positive organisms and anti-biofouling activity. Their ability to inhibit growth and proliferation of cancer cell line was also examined, and it could be seen that AgNPs synthesized using D. radiodurans exhibited excellent anticancer activity.

  9. Proteome dynamics during post-desiccation recovery reveal convergence of desiccation and gamma radiation stress response pathways in Deinococcus radiodurans.

    Science.gov (United States)

    Ujaoney, Aman Kumar; Padwal, Mahesh Kumar; Basu, Bhakti

    2017-09-01

    Deinococcus radiodurans is inherently resistant to both ionizing radiation and desiccation. Fifteen months of desiccation was found to be the LD50 dose for D. radiodurans. Desiccated cells of D. radiodurans entered 6h of growth arrest during post-desiccation recovery (PDR). Proteome dynamics during PDR were mapped by resolving cellular proteins by 2-dimensional gel electrophoresis coupled with mass spectrometry. At least 41 proteins, represented by 51 spots on proteome profiles, were differentially expressed throughout PDR. High upregulation in expression was observed for DNA repair proteins involved in single strand annealing (DdrA and DdrB), nucleotide excision repair (UvrA and UvrB), homologous recombination (RecA) and other vital proteins that contribute to DNA replication, recombination and repair (Ssb, GyrA and GyrB). Expression of CRP/FNR family transcriptional regulator (Crp) remained high throughout PDR. Other pathways such as cellular detoxification, protein homeostasis and metabolism displayed both, moderately induced and repressed proteins. Functional relevance of proteomic modulations to surviving desiccation stress is discussed in detail. Comparison of our data with the published literature revealed convergence of radiation and desiccation stress responses of D. radiodurans. This is the first report that substantiates the hypothesis that the radiation stress resistance of D. radiodurans is incidental to its desiccation stress resistance. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. A tamB homolog is involved in maintenance of cell envelope integrity and stress resistance of Deinococcus radiodurans.

    Science.gov (United States)

    Yu, Jiangliu; Li, Tao; Dai, Shang; Weng, Yulan; Li, Jiulong; Li, Qinghao; Xu, Hong; Hua, Yuejin; Tian, Bing

    2017-04-06

    The translocation and assembly module (TAM) in bacteria consists of TamA and TamB that form a complex to control the transport and secretion of outer membrane proteins. Herein, we demonstrated that the DR_1462-DR_1461-DR_1460 gene loci on chromosome 1 of Deinococcus radiodurans, which lacks tamA homologs, is a tamB homolog (DR_146T) with two tamB motifs and a DUF490 motif. Mutation of DR_146T resulted in cell envelope peeling and a decrease in resistance to shear stress and osmotic pressure, as well as an increase in oxidative stress resistance, consistent with the phenotype of a surface layer (S-layer) protein SlpA (DR_2577) mutant, demonstrating the involvement of DR_146T in maintenance of cell envelope integrity. The 123 kDa SlpA was absent and only its fragments were present in the cell envelope of DR_146T mutant, suggesting that DR_146T might be involved in maintenance of the S-layer. A mutant lacking the DUF490 motif displayed only a slight alteration in phenotype compared with the wild type, suggesting DUF490 is less important than tamB motif for the function of DR_146T. These findings enhance our understanding of the properties of the multilayered envelope in extremophilic D. radiodurans, as well as the diversity and functions of TAMs in bacteria.

  11. Identification of new genes contributing to the extreme radioresistance of Deinococcus radiodurans using a Tn5-based transposon mutant library.

    Directory of Open Access Journals (Sweden)

    Rémi Dulermo

    Full Text Available Here, we have developed an extremely efficient in vivo Tn5-based mutagenesis procedure to construct a Deinococcus radiodurans insertion mutant library subsequently screened for sensitivity to genotoxic agents such as γ and UV radiations or mitomycin C. The genes inactivated in radiosensitive mutants belong to various functional categories, including DNA repair functions, stress responses, signal transduction, membrane transport, several metabolic pathways, and genes of unknown function. Interestingly, preliminary characterization of previously undescribed radiosensitive mutants suggests the contribution of cyclic di-AMP signaling in the recovery of D. radiodurans cells from genotoxic stresses, probably by modulating several pathways involved in the overall cell response. Our analyses also point out a new transcriptional regulator belonging to the GntR family, encoded by DR0265, and a predicted RNase belonging to the newly described Y family, both contributing to the extreme radioresistance of D. radiodurans. Altogether, this work has revealed new cell responses involved either directly or indirectly in repair of various cell damage and confirmed that D. radiodurans extreme radiation resistance is determined by a multiplicity of pathways acting as a complex network.

  12. Une vie consacrée à la science du Sahara et de son passé

    OpenAIRE

    Sèbe, Berny

    2014-01-01

    Né en 1916, Henri-Jean Hugot est le dernier représentant de l’élite des savants pluri-disciplinaires du Sahara encore parmi nous. A l’instar des Théodore Monod ou des Henri Lhote, qui nous ont quittés dans les deux dernières décennies, il s’est intéressé au cours de sa longue carrière scientifique à de nombreux aspects du passé des grands espaces sahariens, offrant des perspectives pionnières qui ont permis de notables avancées dans la compréhension des populations préhistoriques du Sahara. ...

  13. Geochemical and mineralogical evidence for Sahara and Sahel dust additions to Quaternary soils on Lanzarote, eastern Canary Islands, Spain

    Science.gov (United States)

    Muhs, D.R.; Budahn, J.; Skipp, G.; Prospero, J.M.; Patterson, D.; Bettis, E. Arthur

    2010-01-01

    Africa is the most important source of dust in the world today, and dust storms are frequent on the nearby Canary Islands. Previous workers have inferred that the Sahara is the most important source of dust to Canary Islands soils, with little contribution from the Sahel region. Soils overlying a late Quaternary basalt flow on Lanzarote, Canary Islands, contain, in addition to volcanic minerals, quartz and mica, exotic to the island's bedrock. Kaolinite in the soils also likely has an exotic origin. Trace-element geochemistry shows that the soils are derived from varying proportions of locally derived basalt and African dust. Major-element geochemistry, clay mineralogy and interpretation of satellite imagery suggest that dust additions to the Canary Islands come not only from the Sahara Desert, but also from the Sahel region. ?? Published 2010. This article is a US Government work and is in the public domain in the USA.

  14. Presence and Origin of Fluoride in the Complex Terminal Water of Ouargla Basin (Northern Sahara of Algeria)

    OpenAIRE

    Imed E. Nezli; Samia Achour; Mohamed Djidel; Saïd Attalah

    2009-01-01

    Problem statement: The underground waters in the oriental regions of the Algerian Sahara, present real chemical quality problems. Their content in fluorides always exceeds the limit of the recommended levels. That is 0.8 mg L-1, according to the maximum temperature in the region. Combined to a high salinity, it affects the health of the population living around the region. The present work, deals with the presence of fluoride and the geochemical origin in the Complex Terminal aquifer of Ouarg...

  15. Viruses in the desert: a metagenomic survey of viral communities in four perennial ponds of the Mauritanian Sahara

    OpenAIRE

    Fancello, Laura; Trape, S?batien; Robert, Catherine; Boyer, Micka?l; Popgeorgiev, Nikolay; Raoult, Didier; Desnues, Christelle

    2012-01-01

    Here, we present the first metagenomic study of viral communities from four perennial ponds (gueltas) located in the central Sahara (Mauritania). Three of the four gueltas (Ilij, Molomhar and Hamdoun) are located at the source of three different wadis belonging to the same hydrologic basin, whereas the fourth (El Berbera) belongs to a different basin. Overall, sequences belonging to tailed bacteriophages were the most abundant in all four metagenomes although electron microscopy and sequencin...

  16. Mosquito records from the Republic of Niger, with reference to the construction of the new 'Trans-Sahara Highway'.

    Science.gov (United States)

    Smith, D M

    1981-06-01

    Construction of a new, fully-tarred 'Trans-Sahara Highway' from the coast of Algeria to Nigeria is well advanced. Information on the distribution of anopheline and culicine mosquitoes collected in Niger during a survey in August and September, 1979 is presented and discussed. Particular reference is made to the dangers of West African malaria vectors being transported north along the Highway as traffic increases. The vector species, Anopheles arabiensis, was found as far north as Agadez (17 degrees N).

  17. Crater palaeolakes in the Tibesti mountains (Central Sahara, North Chad) - New insights into past Saharan climates

    Science.gov (United States)

    Kröpelin, Stefan; Dinies, Michèle; Sylvestre, Florence; Hoelzmann, Philipp

    2016-04-01

    For the first time continuous lacustrine sections were sampled from the volcanic Tibesti Mountains (Chad): In the 900 m deep crater of Trou au Natron at Pic Toussidé (3,315 m a.s.l.) and from the 800 m deep Era Kohor, the major sub-caldera of Emi Koussi (3,445 m a.s.l.). The remnant diatomites on their slopes are located 360 m (Trou au Natron) and 125 m (Era Kohor) above the present day bottom of the calderas. These sediments from highly continental positions in the central Sahara are keys for the reconstruction of the last climatic cycles (Kröpelin et al. 2015). We report first results from sedimentary-geochemical (total organic and total inorganic carbon contents; total nitrogen; major elements; mineralogy) and palynological analyses for palaeo-environmental interpretations. The diatomites from the Trou au Natron comprise 330 cm of mostly calcitic sediments with relatively low organic carbon (moss/fern stands. Regional pollen rain-e.g. grasses and wormwood-is scarcely represented. Golden algae dominate in the lower section. The results of the first palynological samples suggest a small sedimentation basin. Two 14C-dated charcoals out of the upper part of the section indicate mid-Holocene ages and a linear extrapolation based on a sediment accumulation rate of 1.4mma-1 would lead to tentative dates of ~8650 cal a BP for basal lacustrine sediments and ~4450 cal a BP for the cessation of this lacustrine sequence. The diatomites from the Era Kohor reflect a suite of sections that in total sum up to 145 cm of mostly silica-based sediments with very low carbon contents (flora mainly composed of benthic and tychoplanktonic species, indicating a shallow freshwater lake. Both diatomite sequences thus suggest shallow lakes throughout their deposition-whether this is due to their marginal position within the large calderas and/or shallow waters covered the entire calderas is an outstanding question that will be addressed with planned additional investigations. Kr

  18. Ethnoveterinary of Sahrawi pastoralists of Western Sahara: camel diseases and remedies.

    Science.gov (United States)

    Volpato, Gabriele; Lamin Saleh, Saleh Mohamed; Di Nardo, Antonello

    2015-06-20

    Pastoral populations around the world hold complex and detailed ethnoveterinary knowledge, essential for the survival of their herds and securing their livelihood. In recent decades, several studies have given attention to local veterinary remedies and practices and their validation, and to the local conceptualization of livestock diseases. Despite this, relatively little has been reported on indigenous knowledge of camel diseases (e.g., aetiological factors, epidemiological patterns, symptoms, prevention and treatments). This paper focuses on the traditional knowledge of camel diseases and their treatments among Sahrawi nomads, detailing how this knowledge is powerfully reflected on pastoral adaptation strategies to the ecological system of Western Sahara. Between 2005 and 2010, freelisting exercise on camel diseases with 46 Sahrawi nomads and refugees, semi-structured interviews with 36 knowledgeable informants about camel diseases and associated treatments, and a voucher specimen collection of the plants and products cited were conducted in the territories administered by the Saharawi Arab Democratic Republic, Western Sahara. Analytical methods included standard ethnobiological, ethnobotanical and cultural consensus analyses. In total, 42 camel diseases were freelisted by informants, with four (i.e., mange, dermatomycosis, respiratory infections, and mastitis) found to be culturally highly salient. These four represent the most common veterinary conditions experienced by Sahrawi pastoralists. In addition, 42 plant species belonging to 22 botanical families (Hammada scoparia, Acacia tortilis, Zygophyllum gaetulum, Nucularia perrinii, and Panicum turgidum among the species most used) were listed as used in the treatment of these diseases, as well as about 30 remedies of animal (e.g., from camels, donkeys, and/or spiny-tailed lizards) and mineral origin, and of cauterizations. This study provides an overall picture of the most important camel diseases and remedies

  19. Herminiimonas arsenicoxydans sp. nov., a metalloresistant bacterium.

    Science.gov (United States)

    Muller, Daniel; Simeonova, Diliana D; Riegel, Philippe; Mangenot, Sophie; Koechler, Sandrine; Lièvremont, Didier; Bertin, Philippe N; Lett, Marie-Claire

    2006-08-01

    An arsenite-oxidizing bacterium, designated strain ULPAs1(T), was isolated from industrial sludge heavily contaminated with arsenic. Cells of this isolate were Gram-negative, curved rods, motile by means of a polar flagellum. The strain was positive for oxidase and catalase activities, was able to reduce nitrate to nitrite, used acetate, lactate and peptone as organic carbon sources under aerobic conditions and was able to oxidize arsenite (As[III]) to arsenate (As[V]). 16S rRNA gene sequence analysis and the absence of dodecanoic fatty acids suggested that this strain represents a member of the genus Herminiimonas of the family Oxalobacteraceae, order Burkholderiales in the Betaproteobacteria. Genomic DNA-DNA hybridization between strain ULPAs1(T) and Herminiimonas fonticola S-94(T) and between strain ULPAs1(T) and Herminiimonas aquatilis CCUG 36956(T) revealed levels of relatedness of <10 %, well below the recommended 70 % species cut-off value. Thus, strain ULPAs1(T) (=CCM 7303(T)=DSM 17148(T)=LMG 22961(T)) is the type strain of a novel species of Herminiimonas, for which the name Herminiimonas arsenicoxydans sp. nov. is proposed.

  20. Experimental evolution of aging in a bacterium

    Directory of Open Access Journals (Sweden)

    Stearns Stephen C

    2007-07-01

    Full Text Available Abstract Background Aging refers to a decline in reproduction and survival with increasing age. According to evolutionary theory, aging evolves because selection late in life is weak and mutations exist whose deleterious effects manifest only late in life. Whether the assumptions behind this theory are fulfilled in all organisms, and whether all organisms age, has not been clear. We tested the generality of this theory by experimental evolution with Caulobacter crescentus, a bacterium whose asymmetric division allows mother and daughter to be distinguished. Results We evolved three populations for 2000 generations in the laboratory under conditions where selection was strong early in life, but very weak later in life. All populations evolved faster growth rates, mostly by decreasing the age at first division. Evolutionary changes in aging were inconsistent. The predominant response was the unexpected evolution of slower aging, revealing the limits of theoretical predictions if mutations have unanticipated phenotypic effects. However, we also observed the spread of a mutation causing earlier aging of mothers whose negative effect was reset in the daughters. Conclusion Our results confirm that late-acting deleterious mutations do occur in bacteria and that they can invade populations when selection late in life is weak. They suggest that very few organisms – perhaps none- can avoid the accumulation of such mutations over evolutionary time, and thus that aging is probably a fundamental property of all cellular organisms.

  1. Crystal structure of the Deinococcus radiodurans single-stranded DNA-binding protein suggests a mechanism for coping with DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, Douglas A.; Eggington, Julie M.; Killoran, Michael P.; Misic, Ana M.; Cox, Michael M.; Keck, James L. (UW)

    2010-11-16

    Single-stranded DNA (ssDNA)-binding (SSB) proteins are uniformly required to bind and protect single-stranded intermediates in DNA metabolic pathways. All bacterial and eukaryotic SSB proteins studied to date oligomerize to assemble four copies of a conserved domain, called an oligonucleotide/oligosaccharide-binding (OB) fold, that cooperate in nonspecific ssDNA binding. The vast majority of bacterial SSB family members function as homotetramers, with each monomer contributing a single OB fold. However, SSB proteins from the Deinococcus-Thermus genera are exceptions to this rule, because they contain two OB folds per monomer. To investigate the structural consequences of this unusual arrangement, we have determined a 1.8-{angstrom}-resolution x-ray structure of Deinococcus radiodurans SSB. The structure shows that D. radiodurans SSB comprises two OB domains linked by a {beta}-hairpin motif. The protein assembles a four-OB-fold arrangement by means of symmetric dimerization. In contrast to homotetrameric SSB proteins, asymmetry exists between the two OB folds of D. radiodurans SSB because of sequence differences between the domains. These differences appear to reflect specialized roles that have evolved for each domain. Extensive crystallographic contacts link D. radiodurans SSB dimers in an arrangement that has important implications for higher-order structures of the protein bound to ssDNA. This assembly utilizes the N-terminal OB domain and the {beta}-hairpin structure that is unique to Deinococcus and Thermus species SSB proteins. We hypothesize that differences between D. radiodurans SSB and homotetrameric bacterial SSB proteins may confer a selective advantage to D. radiodurans cells that aids viability in environments that challenge genomic stability.

  2. A bacterium that degrades and assimilates poly(ethylene terephthalate)

    National Research Council Canada - National Science Library

    Yoshida, Shosuke; Hiraga, Kazumi; Takehana, Toshihiko; Taniguchi, Ikuo; Yamaji, Hironao; Maeda, Yasuhito; Toyohara, Kiyotsuna; Miyamoto, Kenji; Kimura, Yoshiharu; Oda, Kohei

    2016-01-01

    .... By screening natural microbial communities exposed to PET in the environment, we isolated a novel bacterium, Ideonella sakaiensis 201-F6, that is able to use PET as its major energy and carbon source...

  3. A bacterium that degrades and assimilates polyethylene terephthalate

    National Research Council Canada - National Science Library

    Yoshida, Shosuke; Hiraga, Kazumi; Takehana, Toshihiko; Taniguchi, Ikuo; Yamaji, Hironao; Maeda, Yasuhito; Toyohara, Kiyotsuna; Miyamoto, Kenj i; Kimura, Yoshiharu; Oda, Kohei

    2016-01-01

    .... By screening natural microbial communities exposed to PET in the environment, we isolated a novel bacterium, Ideonella sakaiensis 201-F6, that is able to use PET as its major energy and carbon source...

  4. Barriers to utilisation of cervical cancer screening in Sub Sahara Africa: a systematic review.

    Science.gov (United States)

    Lim, J N W; Ojo, A A

    2017-01-01

    Cervical cancer is the commonest cause of cancer-related death in Sub Sahara Africa (SSA). Both primary and secondary preventive services are available but utilisation remain low. This systematic review aims to summarise reported barriers preventing women from utilising cervical cancer screening services in SSA. Electronic searches on MEDLINE, EMBASE, PsycINFO, BIOSIS preview, Global Health, PubMed, Cochrane library, CINAHL, ISI Web of Knowledge and Google scholar and quality assessment of the included studies were performed. A meta-analysis was applied to identify major themes. Eight studies exploring reasons women did not utilise cervical cancer screening were included. Women in SSA reported similar barriers despite cultural and language diversity in the region. Women reported fear of screening procedure and negative outcome, low level of awareness of services, embarrassment and possible violation of privacy, lack of spousal support, societal stigmatisation, cost of accessing services and health service factors like proximity to facility, facility navigation, waiting time and health care personnel attitude. Strategies for improving uptake and utilisation of cervical screening in SSA should focus on improving cervical health education, addressing cultural beliefs and practices and improving spousal support and empowering women, as well as addressing physical access problem, costs and improving staff attitude. © 2016 John Wiley & Sons Ltd.

  5. Microbial Diversity of the Hypersaline Sidi Ameur and Himalatt Salt Lakes of the Algerian Sahara.

    Science.gov (United States)

    Boutaiba, Saad; Hacene, Hocine; Bidle, Kelly A; Maupin-Furlow, Julie A

    2011-10-01

    Microbial populations within hypersaline lakes often exhibit high activities of photosynthesis, dissimilatory sulphate reduction and other processes and, thus, can have profound impacts on biogeochemical cycles of carbon, nitrogen, sulphur and other important elements within arid lands. To further understand these types of ecosystems, the physicochemical and biological properties of Sidi Ameur and Himalatt Salt Lakes in the Algerian Sahara were examined and compared. Both lakes were relatively neutral in pH (7.2 to 7.4) and high in salt, at 12% and 20 % (w/v) salinity for Himalatt and Sidi Ameur Lakes, respectively, with dominant ions of sodium and chloride. The community compositions of microbes from all three domains (Bacteria, Archaea and Eukarya) were surveyed through the use of 16S and 18S ribosomal gene amplification and clone library clustering using amplified ribosomal DNA restriction analysis (ARDRA) in conjunction with DNA sequencing and analysis. A high level of microbial diversity, particularly among the bacteria of the Himalatt Salt Lake and archaea of Sidi Ameur Lake, was found within these environments. Representatives from all known halophilic bacterial phyla as well as 6 different genera of halophilic archaea were identified. Moreover, several apparently novel phylotypes among both archaea and bacteria were revealed.

  6. Trapping or tethering stones (TS): A multifunctional device in the Pastoral Neolithic of the Sahara

    Science.gov (United States)

    di Lernia, Savino

    2018-01-01

    The Pierres de Ben Barour, also known as trapping or tethering stones (TS), are stone artefacts with notches or grooves usually interpreted as hunting devices on the basis of rock art engravings. Though their presence is a peculiar feature of desert landscapes from the Sahara to the Arabian Peninsula, we know little about their age, context and function. Here we present a new approach to the study of these artefacts based on a large dataset (837 items) recorded in the Messak plateau (SW Libya). A statistically-based geoarchaeological survey carried out between 2007 and 2011 in Libya, alongside landscape and intra-site analyses of specific archaeological features (such as rock art, settlement and ceremonial contexts), reveal that these artefacts were used for a prolonged period, probably from the early Holocene. This was followed by a multifunctional use of these devices, particularly during the Pastoral Neolithic phase (ca. 6400–3000 cal BC), with the highest concentrations being found near ceremonial contexts related to cattle burials. PMID:29370242

  7. Airborne Fungi in Sahara Dust Aerosols Reaching the Eastern Caribbean: II. Species Identification Using Molecular Techniques

    Science.gov (United States)

    de La Mota, A.; Betancourt, C.; Detres, Y.; Armstrong, R.

    2003-12-01

    Fungi samples from filters collected in Castle Bruce, Dominica from March through July 2002, were previously purified and identified to genus level using classic macroscopic and microscopic techniques. A total of 105 isolated colonies were cultured in liquid media and the mycelial mats used for DNA extraction. PCR was used to amplify the ITS region of the rDNA using the ITS1 and ITS4 primers. Both strands of the amplified products were sequenced and the final identification to species level was completed by a GenBank search. Fourteen different species and one fungal endophyte were identified from genders Aspergillus,Penicillium, Fusarium, Cladosporium, Curvularia and Phanerochaete. Some of these species such as A. fumigatus, A. japonicus, P. citrinum and C. cladosporoides are known to cause respiratory disorders in humans. A. fumigatus causes an aggressive pulmonary allergic response that might result in allergic bronchopulmonary aspergillosis. Other species such as F. equiseti and C. brachyspora are plant pathogens affecting economically important crops. Sahara dust is an important source of fungal spores of species that are not common in the Caribbean region.

  8. The Right to Self-Determination and Natural Resources: The Case of Western Sahara

    Directory of Open Access Journals (Sweden)

    Hans Morten Haugen

    2007-06-01

    Full Text Available Phosphate, fish and possibly oil and gas all constitute important natural resources found on the territory and in the waters of Western Sahara. The importance of these natural resources must be recognised in order to understand the stalemate in the attempted process of decolonisation from Morocco which has been going on for more than 30 years. The article analyses the ‘resource dimension’ of the right to self-determination, as recognised in human rights treaties and in Resolution III of the UN Conference on the Law of the Seas, as well as several resolutions from the United Nations General Assembly. If the resources are exploited in a manner which does not benefit the peoples seeking to enjoy the right to self-determination, such exploitation is illegal. The article shows that the current exploitation takes place in a manner contrary to the interests of the local population, the Saharawis. The article also demonstrates that recent license agreements with Saharawi authorities in the field of oil and gas, signal a potentially new and constructive approach by international corporations.

  9. Taxonomic characterization of the cellulose-degrading bacterium NCIB 10462

    Energy Technology Data Exchange (ETDEWEB)

    Dees, C.; Ringleberg, D.; Scott, T.C. [Oak Ridge National Lab., TN (United States); Phelps, T. [Univ. of Tennessee, Knoxville, TN (United States)

    1994-06-01

    The gram negative cellulase-producing bacterium NCIB 10462 has been previously named Pseudomonas fluorescens subsp. or var. cellulosa. Since there is renewed interest in cellulose-degrading bacteria for use in bioconversion of cellulose to chemical feed stocks and fuels, we re-examined the characteristics of this microorganism to determine its proper taxonomic characterization and to further define it`s true metabolic potential. Metabolic and physical characterization of NCIB 10462 revealed that this was an alkalophilic, non-fermentative, gram negative, oxidase positive, motile, cellulose-degrading bacterium. The aerobic substrate utilization profile of this bacterium was found to have few characteristics consistent with a classification of P. fluorescens with a very low probability match with the genus Sphingomonas. Total lipid analysis did not reveal that any sphingolipid bases are produced by this bacterium. NCIB 10462 was found to grow best aerobically but also grows well in complex media under reducing conditions. NCIB 10462 grew slowly under full anaerobic conditions on complex media but growth on cellulosic media was found only under aerobic conditions. Total fatty acid analysis (MIDI) of NCIB 10462 failed to group this bacterium with a known pseudomonas species. However, fatty acid analysis of the bacteria when grown at temperatures below 37{degrees}C suggest that the organism is a pseudomonad. Since a predominant characteristic of this bacterium is it`s ability to degrade cellulose, we suggest it be called Pseudomonas cellulosa.

  10. Stress induction in the bacteria Shewanella oneidensis and Deinococcus radiodurans in response to below-background ionizing radiation.

    Science.gov (United States)

    Castillo, Hugo; Schoderbek, Donald; Dulal, Santosh; Escobar, Gabriela; Wood, Jeffrey; Nelson, Roger; Smith, Geoffrey

    2015-01-01

    The 'Linear no-threshold' (LNT) model predicts that any amount of radiation increases the risk of organisms to accumulate negative effects. Several studies at below background radiation levels (4.5-11.4 nGy h(-1)) show decreased growth rates and an increased susceptibility to oxidative stress. The purpose of our study is to obtain molecular evidence of a stress response in Shewanella oneidensis and Deinococcus radiodurans grown at a gamma dose rate of 0.16 nGy h(-1), about 400 times less than normal background radiation. Bacteria cultures were grown at a dose rate of 0.16 or 71.3 nGy h(-1) gamma irradiation. Total RNA was extracted from samples at early-exponential and stationary phases for the rt-PCR relative quantification (radiation-deprived treatment/background radiation control) of the stress-related genes katB (catalase), recA (recombinase), oxyR (oxidative stress transcriptional regulator), lexA (SOS regulon transcriptional repressor), dnaK (heat shock protein 70) and SOA0154 (putative heavy metal efflux pump). Deprivation of normal levels of radiation caused a reduction in growth of both bacterial species, accompanied by the upregulation of katB, recA, SOA0154 genes in S. oneidensis and the upregulation of dnaK in D. radiodurans. When cells were returned to background radiation levels, growth rates recovered and the stress response dissipated. Our results indicate that below-background levels of radiation inhibited growth and elicited a stress response in two species of bacteria, contrary to the LNT model prediction.

  11. Regulation of Deinococcus radiodurans RecA protein function via modulation of active and inactive nucleoprotein filament states.

    Science.gov (United States)

    Ngo, Khanh V; Molzberger, Eileen T; Chitteni-Pattu, Sindhu; Cox, Michael M

    2013-07-19

    The RecA protein of Deinococcus radiodurans (DrRecA) has a central role in genome reconstitution after exposure to extreme levels of ionizing radiation. When bound to DNA, filaments of DrRecA protein exhibit active and inactive states that are readily interconverted in response to several sets of stimuli and conditions. At 30 °C, the optimal growth temperature, and at physiological pH 7.5, DrRecA protein binds to double-stranded DNA (dsDNA) and forms extended helical filaments in the presence of ATP. However, the ATP is not hydrolyzed. ATP hydrolysis of the DrRecA-dsDNA filament is activated by addition of single-stranded DNA, with or without the single-stranded DNA-binding protein. The ATPase function of DrRecA nucleoprotein filaments thus exists in an inactive default state under some conditions. ATPase activity is thus not a reliable indicator of DNA binding for all bacterial RecA proteins. Activation is effected by situations in which the DNA substrates needed to initiate recombinational DNA repair are present. The inactive state can also be activated by decreasing the pH (protonation of multiple ionizable groups is required) or by addition of volume exclusion agents. Single-stranded DNA-binding protein plays a much more central role in DNA pairing and strand exchange catalyzed by DrRecA than is the case for the cognate proteins in Escherichia coli. The data suggest a mechanism to enhance the efficiency of recombinational DNA repair in the context of severe genomic degradation in D. radiodurans.

  12. Deinococcus radiodurans RecA nucleoprotein filaments characterized at the single-molecule level with optical tweezers.

    Science.gov (United States)

    Pobegalov, Georgii; Cherevatenko, Galina; Alekseev, Aleksandr; Sabantsev, Anton; Kovaleva, Oksana; Vedyaykin, Alexey; Morozova, Natalia; Baitin, Dmitrii; Khodorkovskii, Mikhail

    2015-10-23

    Deinococcus radiodurans can survive extreme doses of ionizing radiation due to the very efficient DNA repair mechanisms that are able to cope even with hundreds of double-strand breaks. RecA, the critical protein of homologous recombination in bacteria, is one of the key components of the DNA-repair system. Repair of double-strand breaks requires RecA binding to DNA and assembly of the RecA nucleoprotein helical filaments. The Escherichia coli RecA protein (EcRecA) and its interactions with DNA have been extensively studied using various approaches including single-molecule techniques, while the D. radiodurans RecA (DrRecA) remains much less characterized. However, DrRecA shows some remarkable differences from E. coli homolog. Here we combine microfluidics and single-molecule DNA manipulation with optical tweezers to follow the binding of DrRecA to long double-stranded DNA molecules and probe the mechanical properties of DrRecA nucleoprotein filaments at physiological pH. Our data provide a direct comparison of DrRecA and EcRecA binding to double-stranded DNA under identical conditions. We report a significantly faster filaments assembly as well as lower values of persistence length and contour length for DrRecA nucleoprotein filaments compared to EcRecA. Our results support the existing model of DrRecA forming more frequent and less continuous filaments relative to those of EcRecA. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Structures of trehalose synthase from Deinococcus radiodurans reveal that a closed conformation is involved in catalysis of the intramolecular isomerization.

    Science.gov (United States)

    Wang, Yung Lin; Chow, Sih Yao; Lin, Yi Ting; Hsieh, Yu Chiao; Lee, Guan Chiun; Liaw, Shwu Huey

    2014-12-01

    Trehalose synthase catalyzes the simple conversion of the inexpensive maltose into trehalose with a side reaction of hydrolysis. Here, the crystal structures of the wild type and the N253A mutant of Deinococcus radiodurans trehalose synthase (DrTS) in complex with the inhibitor Tris are reported. DrTS consists of a catalytic (β/α)8 barrel, subdomain B, a C-terminal β domain and two TS-unique subdomains (S7 and S8). The C-terminal domain and S8 contribute the majority of the dimeric interface. DrTS shares high structural homology with sucrose hydrolase, amylosucrase and sucrose isomerase in complex with sucrose, in particular a virtually identical active-site architecture and a similar substrate-induced rotation of subdomain B. The inhibitor Tris was bound and mimics a sugar at the -1 subsite. A maltose was modelled into the active site, and subsequent mutational analysis suggested that Tyr213, Glu320 and Glu324 are essential within the +1 subsite for the TS activity. In addition, the interaction networks between subdomains B and S7 seal the active-site entrance. Disruption of such networks through the replacement of Arg148 and Asn253 with alanine resulted in a decrease in isomerase activity by 8-9-fold and an increased hydrolase activity by 1.5-1.8-fold. The N253A structure showed a small pore created for water entry. Therefore, our DrTS-Tris may represent a substrate-induced closed conformation that will facilitate intramolecular isomerization and minimize disaccharide hydrolysis.

  14. Deinococcus radiodurans DR2231 is a two-metal-ion mechanism hydrolase with exclusive activity on dUTP.

    Science.gov (United States)

    Mota, Cristiano S; Gonçalves, Ana Maria D; de Sanctis, Daniele

    2016-12-01

    DR2231 from Deinococcus radiodurans was previously functionally and structurally characterized as an all-α NTP pyrophosphohydrolase with specific dUTPase activity. dUTPases have a central role in the regulation of dUTP intracellular levels and dTTP nucleotide metabolism. DR2231 presents a conserved dimetal catalytic site, similar to all-α dimeric dUTPases, but contrary to these enzymes, it is unable to process dUDP. In this article, we present functional and structural evidence of single-point mutations that affect directly or indirectly the enzyme catalysis and provide a complete description of the all-α NTP pyrophosphohydrolase mechanism. Activity assays, isothermal titration calorimetry and the crystal structures of these mutants obtained in complex with dUMP or a dUTP analogue aid in probing the reaction mechanism. Our results demonstrate that the two metals are necessary for enzyme processing and also important to modulate the substrate binding affinity. Single-point mutations located in a structurally mobile lid-like loop show that the interactions with the nucleoside monophosphate are essential for induction of the closed conformation and ultimately for substrate processing. β- and γ-phosphates are held in place through coordination with the second metal, which is responsible for the substrate 'gauche' orientation in the catalytic position. The lack of sufficient contacts to orient the dUDP β-phosphate for hydrolysis explains DR2231 preference towards dUTP. Sequence and structural similarities with MazG proteins suggest that a similar mechanism might be conserved within the protein family. Structural data are available in the PDB under the accession numbers 5HVA, 5HWU, 5HX1, 5HYL, 5I0J, 5HZZ, 5I0M. © 2016 Federation of European Biochemical Societies.

  15. Dps from Deinococcus radiodurans: oligomeric forms of Dps1 with distinct cellular functions and Dps2 involved in metal storage.

    Science.gov (United States)

    Santos, Sandra P; Mitchell, Edward P; Franquelim, Henri G; Castanho, Miguel A R B; Abreu, Isabel A; Romão, Célia V

    2015-11-01

    The DNA binding proteins from starved cells from Deinococcus radiodurans, Dps1-DR2263 and Dps2-DRB0092, have a common overall structure of hollow spherical dodecamers. Their involvement in the homeostasis of intracellular metal and DNA protection was addressed. Our results show that DrDps proteins are able to oxidize ferrous to ferric iron by oxygen or hydrogen peroxide. The iron stored inside the hollow sphere cavity is fully released. Furthermore, these proteins are able to store and release manganese, suggesting they can play a role in manganese homeostasis as well. The interaction of DrDps with DNA was also addressed. Even though DrDps1 binds both linear and coiled DNA, DrDps2 preferentially binds to coiled DNA, forming different protein-DNA complexes, as clearly shown by atomic force microscopy. DrDps1 (dimer and dodecamer) and DrDps2 can protect DNA against reactive oxygen species, although the protection occurs at different Fe to protein ratios. The difference between DrDps could be the result of the DrDps1 higher iron oxidation rate in the presence of hydrogen peroxide and its higher affinity to bind DNA than in DrDps2. Using cellular extracts obtained from D. radiodurans cultures, we showed that DrDps1 oligomers observed in in vitro conditions are also present in vivo. This indicates that DrDps1 has a structural dynamic plasticity that allows its oligomeric state to change between dimer, trimer and dodecamer. This in turn suggests the existence of a regulation mechanism that modulates the oligomer equilibrium and is dependent on growth stages and environmental conditions. © 2015 FEBS.

  16. A novel OxyR sensor and regulator of hydrogen peroxide stress with one cysteine residue in Deinococcus radiodurans.

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    Huan Chen

    Full Text Available In bacteria, OxyR is a peroxide sensor and transcription regulator, which can sense the presence of reactive oxygen species and induce antioxidant system. When the cells are exposed to H(2O(2, OxyR protein is activated via the formation of a disulfide bond between the two conserved cysteine residues (C199 and C208. In Deinococcus radiodurans, a previously unreported special characteristic of DrOxyR (DR0615 is found with only one conserved cysteine. dr0615 gene mutant is hypersensitive to H(2O(2, but only a little to ionizing radiation. Site-directed mutagenesis and subsequent in vivo functional analyses revealed that the conserved cysteine (C210 is necessary for sensing H(2O(2, but its mutation did not alter the binding characteristics of OxyR on DNA. Under oxidant stress, DrOxyR is oxidized to sulfenic acid form, which can be reduced by reducing reagents. In addition, quantitative real-time PCR and global transcription profile results showed that OxyR is not only a transcriptional activator (e.g., katE, drb0125, but also a transcriptional repressor (e.g., dps, mntH. Because OxyR regulates Mn and Fe ion transporter genes, Mn/Fe ion ratio is changed in dr0615 mutant, suggesting that the genes involved in Mn/Fe ion homeostasis, and the genes involved in antioxidant mechanism are highly cooperative under extremely oxidant stress. In conclusion, these findings expand the OxyR family, which could be divided into two classes: typical 2-Cys OxyR and 1-Cys OxyR.

  17. Quantitative Characterization of the Growth of Deinococcus geothermalis DSM-11302: Effect of Inoculum Size, Growth Medium and Culture Conditions

    Directory of Open Access Journals (Sweden)

    Julie Bornot

    2015-08-01

    Full Text Available Due to their remarkable resistance to extreme conditions, Deinococcaceae strains are of great interest to biotechnological prospects. However, the physiology of the extremophile strain Deinococcus geothermalis has scarcely been studied and is not well understood. The physiological behaviour was then studied in well-controlled conditions in flask and bioreactor cultures. The growth of D. geothermalis type strains was compared. Among the strains tested, the strain from the German Collection of Microorganisms (Deutsche Sammlung von Mikroorganismen DSM DSM-11302 was found to give the highest biomass concentration and growth rate: in a complex medium with glucose, the growth rate reached 0.75 h−1 at 45 °C. Yeast extract concentration in the medium had significant constitutive and catalytic effects. Furthermore, the results showed that the physiological descriptors were not affected by the inoculum preparation steps. A batch culture of D. geothermalis DSM-11302 on defined medium was carried out: cells grew exponentially with a maximal growth rate of 0.28 h−1 and D. geothermalis DSM-11302 biomass reached 1.4 g·L−1 in 20 h. Then, 1.4 gDryCellWeight of biomass (X was obtained from 5.6 g glucose (Glc consumed as carbon source, corresponding to a yield of 0.3 CmolX·CmolGlc−1; cell specific oxygen uptake and carbon dioxide production rates reached 216 and 226 mmol.CmolX−1·h−1, respectively, and the respiratory quotient (QR value varied from 1.1 to 1.7. This is the first time that kinetic parameters and yields are reported for D. geothermalis DSM-11302 grown on a mineral medium in well-controlled batch culture.

  18. RNA-Binding Domain is Necessary for PprM Function in Response to the Extreme Environmental Stress in Deinococcus radiodurans.

    Science.gov (United States)

    Li, Wei; Ma, Yun; Yang, Jie; Xiao, Fangzhu; Wang, Wuzhou; He, Shuya

    2017-12-01

    Deinococcus radiodurans was considered as one of the most radiation-resistant organisms on Earth because of its strong resistance to the damaging factors of both DNA and protein, including ionizing radiation, ultraviolet radiation, oxidants, and desiccation. PprM, as a bacterial cold shock protein homolog, was involved in the radiation resistance and oxidative stress response of D. radiodurans, but its potential mechanisms are poorly expounded. In this study, we found that PprM was highly conserved with the RNA-binding domain in Deinococcus genus through performing phylogenic analysis. Moreover, the paper presents the analysis on the tolerance of environmental stresses both in the wild-type and the pprM/pprM RBD mutant strains, demonstrating that pprM and RNA-binding domain disruptant strain were with higher sensitivity than the wild-type strain to cold stress, mitomycin C, UV radiation, and hydrogen peroxide. In the following step, the recombinant PprM was purified, with the finding that PprM was bound to the 5'-untranslated region of its own mRNA by gel mobility shift assay in vitro. With all these findings taken into consideration, it was suggested that PprM act as a cold shock protein and its RNA-binding domain may be involved in reaction to the extreme environmental stress in D. radiodurans.

  19. A forest butterfly in sahara desert oases: isolation does not matter.

    Science.gov (United States)

    Habel, Jan Christian; Husemann, Martin; Schmitt, Thomas; Dapporto, Leonardo; Rödder, Dennis; Vandewoestijne, Sofie

    2013-03-01

    Numerous studies addressing the impact of habitat fragmentation on genetic diversity have been performed. In this study, we analyze the effects of a seemingly nonpermeable matrix on the population structure of the forest-dwelling butterfly Pararge aegeria in geographically isolated oases at the northern margin of the Sahara desert using microsatellites, morphological characters, and species distribution modeling. Results from all analyses are mostly congruent and reveal 1) a split between European and North African populations, 2) rather low divergence between populations from the eastern and western part of North Africa (Morocco vs. Tunisia), 3) a lack of differentiation between the oasis and Atlas Mountain populations, 4) as well as among the oasis populations, and 5) no reduction of genetic variability in oasis populations. However, one exception to this general trend resulted from the analyses of wing shape; wings of butterflies from oases are more elongated compared with those from the other habitats. This pattern of phenotypic divergence may suggest a recent colonization of the oasis habitats by individuals, which might be accompanied by a rather dispersive behavior. Species distribution modeling suggests a fairly recent reexpansion of the species' climatic niche starting in the Holocene at about 6000 before present. The combined results indicate a rather recent colonization of the oases by highly mobile individuals from genetically diverse founder populations. The colonization was likely followed by the expansion and persistence of these founder populations under relatively stable environmental conditions. This, together with low rates of gene flow, likely prevented differentiation of populations via drift and led to the maintenance of high genetic diversity.

  20. Evidence of Rift Valley fever seroprevalence in the Sahrawi semi-nomadic pastoralist system, Western Sahara.

    Science.gov (United States)

    Di Nardo, Antonello; Rossi, Davide; Saleh, Saleh M Lamin; Lejlifa, Saleh M; Hamdi, Sidumu J; Di Gennaro, Annapia; Savini, Giovanni; Thrusfield, Michael V

    2014-04-24

    The increasing global importance of Rift Valley fever (RVF) is clearly demonstrated by its geographical expansion. The presence of a wide range of host and vector species, and the epidemiological characteristics of RVF, have led to concerns that epidemics will continue to occur in previously unaffected regions of Africa. The proximity of the Sahrawi territories of Western Sahara to endemic countries, such as Mauritania, Senegal, and Mali with periodic isolation of virus and serological evidence of RVF, and the intensive livestock trade in the region results in a serious risk of RVF spread in the Sahrawi territories, and potentially from there to the Maghreb and beyond. A sero-epidemiological survey was conducted in the Saharawi territories between March and April 2008 to investigate the possible presence of the RVF virus (RVFV) and associated risk factors. A two-stage cluster sampling design was used, incorporating 23 sampling sites. A total of 982 serum samples was collected from 461 sheep, 463 goats and 58 camels. Eleven samples (0.97%) tested positive for IgG against the RVFV. There were clusters of high seroprevalence located mostly in the Tifariti (7.69%) and Mehaires (7.14%) regions, with the Tifariti event having been found in one single flock (4/26 positive animals). Goats and older animals were at a significantly increased risk being seropositive (p = 0.007 and p = 0.007, respectively). The results suggest potential RVF activity in the study area, where intense livestock movement and trade with neighbouring countries might be considered as a primary determinant in the spread of the disease. The importance of a continuous field investigation is reinforced, in light of the risk of RVF expansion to historically unaffected regions of Africa.

  1. Implications Of Fuelwood Demandon Sustainable Forest Conservation Of The Sub-Sahara Africa

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    Sogbon Odunwole

    2017-04-01

    Full Text Available Forests contribute immensely to economic and social development through formal trade in timber environmental services non- timber forest products safety net spiritual and aesthetic value. Wood is a key source of energy that has been used for millennia for cooking boiling water lighting and heating. Today about 2.5billion people depend on biomass energy for cooking and heating with 87 of this energy being provided by wood. In sub-Saharan African more than 90 of the population relies on wood fire that is firewood and charcoal as their primary source of domestic energy. Over 80 of urban householders and small industries use charcoal and firewood as their source of energy. Despite their numerous importance Africas forest continue to decline rapidly due to increase in agricultural practices into forest lands population growth and urbanization increased poverty high dependence on natural resources for subsistence and income through forest. The study centred on the implications of fuel wood demand on forest conservation in sub-Sahara Africa - a regional focus on Akure metropolitan area Ondo State. The specific objectives of the paper were to identify firewood consumption pattern in Akure metropolitan area and factors responsible for increased fuelwood demand in the study area. The paper adopted direct observation oral interview and 0.05 of the study area as sample size for the study. The study observed lack of adequate alternative poor implementation and enforcement of government regulation on forestry poverty and poor awareness on the menace of forest depletion among others. The paper posited provision of alternative fuel with subsidy regular awareness campaign proper monitoring implementation and enforcement of forest regulations with a view to achieving sustainable conservation.

  2. Crop drying by indirect active hybrid solar - Electrical dryer in the eastern Algerian Septentrional Sahara

    Energy Technology Data Exchange (ETDEWEB)

    Boughali, S.; Bouchekima, B.; Mennouche, D.; Bouguettaia, H.; Bechki, D. [Laboratory of New and Renewable Energy in Aride Zones, University Kasdi Merbah, BP511 Ouargla (Algeria); Benmoussa, H. [Faculty of Science, Department of Mechanics, University Hadj Lakhdar, Batna (Algeria)

    2009-12-15

    In the present work, a new specific prototype of an indirect active hybrid solar-electrical dryer for agricultural products was constructed and investigated at LENREZA Laboratory, University of Ouargla (Algerian Sahara). In the new configuration of air drying passage; the study was done in a somewhat high range of mass flow rate between 0.04 and 0.08 kg/m{sup 2} s a range not properly investigated by most researchers. Experimental tests with and without load were performed in winter season in order to study the thermal behavior of the dryer and the effect of high air masse flow on the collector and system drying efficiency. The fraction of electrical and solar energy contribution versus air mass flow rate was investigated. Slice tomato was studied with different temperatures and velocities of drying air in order to study the influence of these parameters on the removal moisture content from the product and on the kinetics drying and also to determine their suitable values. Many different thin layer mathematical drying models were compared according to their coefficient of determination (R{sup 2}) and reduced chi square ({chi}{sup 2}) to estimate experimental drying curves. The Middli model in this condition proved to be the best for predicting drying behavior of tomato slice with (R{sup 2} = 0.9995, {chi}{sup 2} = 0.0001). Finally an economic evaluation was calculated using the criterion of payback period which is found very small 1.27 years compared to the life of the dryer 15 years. (author)

  3. Detection and Mapping of Sahara Mustard (Brassica tournefortii) in the Colorado Desert of Southern California using Landsat Satellite Imagery

    Science.gov (United States)

    Potter, Christopher S.

    2017-01-01

    Sahara mustard (Brassica tournefortii Gouan), a plant native to North Africa and the Middle East, has become a troublesome invasive pest in arid ecosystems of the Southwest United States, northern and central Mexico, and Australia. In the desert Southwest, B. tournefortii is commonly found in sandy washes, sand sheets, rocky hillsides, and other disturbed areas at elevations below 1000 m. The objective of this study was to evaluate the Landsat MTMF technique for detecting B. tournefortii presence and biomass density in the Colorado Desert region of California.

  4. Essential oil variation in wild populations of Artemisia saharae (Asteraceae) from Tunisia: chemical composition, antibacterial and antioxidant properties.

    Science.gov (United States)

    Zouari, Sami; Ayadi, Imen; Fakhfakh, Nahed; Jdir, Hamida; Aloui, Latifa; Kossentini, Mohamed; Rebai, Ahmed; Zouari, Nacim

    2014-12-01

    Artemisia saharae Pomel is a new taxon of Artemisia herba-alba Asso (Asteraceae) which is endemic to Tunisia and Algeria. This shrub, commonly known as white wormwood or desert wormwood, is largely used in folk medicine and as a culinary herb. The bulks aromatic plants come from wild populations whose essential oils compositions as well as their biological properties are severely affected by several factors such as geographic conditions. Therefore, the aim of the present work is to provide more information about the influence of altitude variation on the essential oil composition, antimicrobial and antioxidant properties of Artemisia saharae growing wild in the same geographical area. Essential oils were extracted by hydrodistillation of leaves and flowers of the plant collected from seven different altitudes of the Baten Zamour region (southwest of Tunisia). The highest essential oil yields (2.70-2.80%) were obtained for populations of high altitudes. Seventy-five compounds, representing 92.78 to 96.95% of the total essential oils, were separated and identified. Essential oils were characterized by very high percentage of oxygenated monoterpenes (52.1-72.6%) which constituted the predominant class. From the analyzed populations, the major compounds (>7%) were α-thujone, β-thujone, chrysanthenone, camphor, chrysanthenyl acetate, and sabinyl acetate. Sabinyl acetate which was detected in some populations at relatively high percentages (7.7-10.8%) seems to be characteristic to Southern Tunisian A. saharae. The studied essential oil showed a chemical diversity depending on the population altitude as revealed by linear discriminant and cluster analyses. Three population groups associated with altitudinal levels were distinguished. It is worthy to note that the most discriminating compounds of chemical groups were the minor ones. Despite the high variation of essential oil compositions, the high altitude population did not affect severely the antibacterial activity

  5. Hydrogen Production by the Thermophilic Bacterium Thermotoga neapolitana

    Science.gov (United States)

    Pradhan, Nirakar; Dipasquale, Laura; d’Ippolito, Giuliana; Panico, Antonio; Lens, Piet N. L.; Esposito, Giovanni; Fontana, Angelo

    2015-01-01

    As the only fuel that is not chemically bound to carbon, hydrogen has gained interest as an energy carrier to face the current environmental issues of greenhouse gas emissions and to substitute the depleting non-renewable reserves. In the last years, there has been a significant increase in the number of publications about the bacterium Thermotoga neapolitana that is responsible for production yields of H2 that are among the highest achievements reported in the literature. Here we present an extensive overview of the most recent studies on this hyperthermophilic bacterium together with a critical discussion of the potential of fermentative production by this bacterium. The review article is organized into sections focused on biochemical, microbiological and technical issues, including the effect of substrate, reactor type, gas sparging, temperature, pH, hydraulic retention time and organic loading parameters on rate and yield of gas production. PMID:26053393

  6. Hydrogen Production by the Thermophilic Bacterium Thermotoga neapolitana

    Directory of Open Access Journals (Sweden)

    Nirakar Pradhan

    2015-06-01

    Full Text Available As the only fuel that is not chemically bound to carbon, hydrogen has gained interest as an energy carrier to face the current environmental issues of greenhouse gas emissions and to substitute the depleting non-renewable reserves. In the last years, there has been a significant increase in the number of publications about the bacterium Thermotoga neapolitana that is responsible for production yields of H2 that are among the highest achievements reported in the literature. Here we present an extensive overview of the most recent studies on this hyperthermophilic bacterium together with a critical discussion of the potential of fermentative production by this bacterium. The review article is organized into sections focused on biochemical, microbiological and technical issues, including the effect of substrate, reactor type, gas sparging, temperature, pH, hydraulic retention time and organic loading parameters on rate and yield of gas production.

  7. Hydrogen Production by the Thermophilic Bacterium Thermotoga neapolitana.

    Science.gov (United States)

    Pradhan, Nirakar; Dipasquale, Laura; d'Ippolito, Giuliana; Panico, Antonio; Lens, Piet N L; Esposito, Giovanni; Fontana, Angelo

    2015-06-04

    As the only fuel that is not chemically bound to carbon, hydrogen has gained interest as an energy carrier to face the current environmental issues of greenhouse gas emissions and to substitute the depleting non-renewable reserves. In the last years, there has been a significant increase in the number of publications about the bacterium Thermotoga neapolitana that is responsible for production yields of H2 that are among the highest achievements reported in the literature. Here we present an extensive overview of the most recent studies on this hyperthermophilic bacterium together with a critical discussion of the potential of fermentative production by this bacterium. The review article is organized into sections focused on biochemical, microbiological and technical issues, including the effect of substrate, reactor type, gas sparging, temperature, pH, hydraulic retention time and organic loading parameters on rate and yield of gas production.

  8. Structure-Based and Random Mutagenesis Approaches Increase the Organophosphate-Degrading Activity of a Phosphotriesterase Homologue from Deinococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Hawwa, Renda; Larsen, Sonia D.; Ratia, Kiira; Mesecar, Andrew D.; (UIC)

    2010-11-09

    An enzyme from the amidohydrolase family from Deinococcus radiodurans (Dr-OPH) with homology to phosphotriesterase has been shown to exhibit activity against both organophosphate (OP) and lactone compounds. We have characterized the physical properties of Dr-OPH and have found it to be a highly thermostable enzyme, remaining active after 3 h of incubation at 60 C and withstanding incubation at temperatures up to 70 C. In addition, it can withstand concentrations of at least 200 mg/mL. These properties make Dr-OPH a promising candidate for development in commercial applications. However, compared to the most widely studied OP-degrading enzyme, that from Pseudomonas diminuta, Dr-OPH has low hydrolytic activity against certain OP substrates. Therefore, we sought to improve the OP-degrading activity of Dr-OPH, specifically toward the pesticides ethyl and methyl paraoxon, using structure-based and random approaches. Site-directed mutagenesis, random mutagenesis, and site-saturation mutagenesis were utilized to increase the OP-degrading activity of Dr-OPH. Out of a screen of more than 30,000 potential mutants, a total of 26 mutant enzymes were purified and characterized kinetically. Crystal structures of w.t. Dr-OPH, of Dr-OPH in complex with a product analog, and of 7 mutant enzymes were determined to resolutions between 1.7 and 2.4 {angstrom}. Information from these structures directed the design and production of 4 additional mutants for analysis. In total, our mutagenesis efforts improved the catalytic activity of Dr-OPH toward ethyl and methyl paraoxon by 126- and 322-fold and raised the specificity for these two substrates by 557- and 183-fold, respectively. Our work highlights the importance of an iterative approach to mutagenesis, proving that large rate enhancements are achieved when mutations are made in already active mutants. In addition, the relationship between the kinetic parameters and the introduced mutations has allowed us to hypothesize on those

  9. Implications of high altitude desert dust transport from Western Sahara to Nile Delta during biomass burning season

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Anup K., E-mail: aprasad@chapman.ed [School of Earth and Environmental Sciences, Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Center of Excellence in Earth Observing, Chapman University, Orange, CA 92866 (United States); El-Askary, Hesham [School of Earth and Environmental Sciences, Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Center of Excellence in Earth Observing, Chapman University, Orange, CA 92866 (United States); Department of Environmental Sciences, Faculty of Science, Alexandria University, Moharem Bek, Alexandria 21522 (Egypt); National Authority for Remote Sensing and Space Science (NARSS), Cairo (Egypt); Kafatos, Menas [School of Earth and Environmental Sciences, Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Center of Excellence in Earth Observing, Chapman University, Orange, CA 92866 (United States)

    2010-11-15

    The air over major cities and rural regions of the Nile Delta is highly polluted during autumn which is the biomass burning season, locally known as black cloud. Previous studies have attributed the increased pollution levels during the black cloud season to the biomass or open burning of agricultural waste, vehicular, industrial emissions, and secondary aerosols. However, new multi-sensor observations (column and vertical profiles) from satellites, dust transport models and associated meteorology present a different picture of the autumn pollution. Here we show, for the first time, the evidence of long range transport of dust at high altitude (2.5-6 km) from Western Sahara and its deposition over the Nile Delta region unlike current Models. The desert dust is found to be a major contributor to the local air quality which was previously considered to be due to pollution from biomass burning enhanced by the dominant northerly winds coming from Europe. - New evidence of desert dust transport from Western Sahara to Nile Delta during black cloud season and its significance for regional aerosols, dust models, and potential impact on the regional climate.

  10. Propolis-Sahara honeys preparation exhibits antibacterial and anti-biofilm activity against bacterial biofims formed on urinary catheters

    Directory of Open Access Journals (Sweden)

    Saad Aissat

    2016-11-01

    Full Text Available Objective: To evaluate the antibacterial effect of Sahara honeys (SHs against bacterial biofilms formed on urinary catheters in combination with propolis-Sahara honeys (P-SHs. Methods: Three clinical isolates were subjected to biofilm detection methods. The antibacterial and anti-biofilm activity for SHs and P-SHs were determined using agar well diffusion and the percentage of biofilm inhibition (PBI methods. Results: The PBI for Gram-positive bacteria [Staphylococcus aureus (S. aureus] was in the range of 0%–20%, while PBI for Gram-negative bacteria [Pseudomonas aeruginosa and Escherichia coli (E. coli] were in range of 17%–57% and 16%–65%, respectively. The highest PBI (65% was produced by SH2 only on E. coli. In agar well diffusion assay, zones of inhibition ranged from 11–20 mm (S. aureus, 9–19 mm (Pseudomonas aeruginosa and 11–19 mm (E. coli. The highest inhibition (20 mm was produced by SH1 only on S. aureus. In addition, the treatment of SHs and P-SHs catheters with a polymicrobial biofilms reduced biofilm formation after 48 h exposure period. Conclussions: SHs and P-SHs applied as a natural agent can be used as a prophylactic agent to prevent the formation of in vitro biofilm.

  11. Asociacionismo y cuestión nacional en el Sahara Occidental

    Directory of Open Access Journals (Sweden)

    Isaías Barreñada

    2012-12-01

    Full Text Available Desde mediados de la década pasada se ha operado una emergencia de la contestación política saharaui en los territorios ocupados por Marruecos. Este fenómeno se debe a varios factores entre los que cabe destacar los escasos resultados de las negociaciones políticas auspiciadas por Naciones Unidas, los cambios políticos operados en Marruecos, la frustración de la población saharaui ante la intensificación de la colonización y una creciente sensación de discriminación. Las protestas están en gran medida estructuradas por un tejido de asociaciones, la mayor parte de ellas alegales, que han hecho de la defensa de los derechos humanos su principal eje de actuación. Sus miembros son tanto antiguos militantes políticos como jóvenes que sólo han conocido la ocupación. El artículo aborda el proceso de articulación de estas asociaciones, sus actuaciones, sus nexos con Marruecos y con el resto de los saharauis, y presta especial atención a su carácter sustitutivo ante la imposibilidad de libre organización de los nacionalistas e independentistas. Since the middle of the last decade a growing political protest has emerged in Western Sahara occupied by Morocco. This phenomenon has been caused by several factors: the little results of the political negotiations under the United Nations, the political changes operated in Morocco, the frustration of the Sahrawi population facing the colonization and an increasing sensation of discrimination. To a great extent the protests are structured by associations, most of them non-legal, which have made of the defense of the human rights their main axis of performance. Most of their members are former political militants as young people who have only known the occupation. The article approaches the process of joining these associations, their performances, their ties with Morocco and the other Sahrawi, and gives special attention to its substitute character before the impossibility of free

  12. Integrated Health Care Systems and Indigenous Medicine: Reflections from the Sub-Sahara African Region

    Directory of Open Access Journals (Sweden)

    Beth Maina Ahlberg

    2017-09-01

    Full Text Available Indigenous or traditional medicine has, since the 1970s, been widely regarded as a resource likely to contribute to strengthening the health care systems in low income countries. This paper examines the state of traditional medicine using evidence from three case studies in Central Kenya. While the cases are too few to represent the broad diversity of cultures and related healing systems in the Sub-Sahara African Region, the way they seem to refute the main assumptions in the integration discourse is important, also because studies from other countries in the region report perspectives, similar to the case studies in Kenya. It is often argued that people continue to use traditional medicine because it is affordable, available, and culturally familiar. Its integration into the health care system would therefore promote cultural familiarity. The case studies however point to the loss of essential cultural elements central to traditional medicine in this particular area while users travel long distances to reach the healers. In addition, there are significant paradigm differences that may present obstacles to integration of the two systems. More problematic however is that integration is, as in many development interventions, a top-down policy that is rarely based on contextual realities and conditions. Instead, integration is often defined and dominated by biomedical professionals and health planners who may be unfamiliar or even hostile to some aspects of traditional medicine. Furthermore, integration efforts have tended to embrace selected components mostly herbal medicine. This has led to isolating herbal medicine from spiritualism, which may in turn affect the holistic perspective of traditional medicine. While familiarity and relevance may explain the continued use of traditional medicine, its services may not be as readily available, accessible, or even affordable as is often asserted. Globalization set in motion through colonization and

  13. Deinococcus radiodurans Toxin?Antitoxin MazEF-dr Mediates Cell Death in Response to DNA Damage Stress

    OpenAIRE

    Tao Li; Yulan Weng; Xiaoqiong Ma; Bing Tian; Shang Dai; Ye Jin; Mengjia Liu; Jiulong Li; Jiangliu Yu; Yuejin Hua

    2017-01-01

    Here we identified a functional MazEF-dr system in the exceptionally stress-resistant bacterium D. radiodurans. We showed that overexpression of the toxin MazF-dr inhibited the growth of Escherichia coli. The toxic effect of MazF-dr was due to its sequence-specific endoribonuclease activity on RNAs containing a consensus 5′ACA3′, and it could be neutralized by MazE-dr. The MazF-dr showed a special cleavage preference for the nucleotide present before the ACA sequence with the order by U>A&...

  14. [Deinococcus radiodurans RecX and Escherichia coli RecX Proteins Are Able to Replace Each Other in vivo and in vitro].

    Science.gov (United States)

    Bakhlanova, I V; Baitin, D M

    2016-03-01

    A plasmid carrying the Deinococcus radiodurans recXgene under the control of a lactose promoter decreases the Escherichia coli cell resistance to UV irradiation and γ irradiation and also influences the conjugational recombination process. The D. radiodurans. RecX protein functions in the Escherichia coli cells similarly to the E. coli RecX protein. Isolated and purified D. radiodurans RecX and E. coli RecX proteins are able to replace each other interacting with the E. coli RecA and D. radiodurans RecA proteins in vitro. Data obtained demonstrated that regulatory interaction of RecA and RecX proteins preserves a high degree of conservatism despite all the differences in the recombination reparation system between E. coli and D. radiodurans.

  15. Microbial Survival Rates of Escherichia coli and Deinococcus radiodurans Under Low Temperature, Low Pressure, and UV-Irradiation Conditions, and Their Relevance to Possible Martian Life

    Science.gov (United States)

    Diaz, Benjamin; Schulze-Makuch, Dirk

    2006-04-01

    Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35°C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m2). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.

  16. Microbial survival rates of Escherichia coli and Deinococcus radiodurans under low temperature, low pressure, and UV-Irradiation conditions, and their relevance to possible Martian life.

    Science.gov (United States)

    Diaz, Benjamin; Schulze-Makuch, Dirk

    2006-04-01

    Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35 degrees C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m(2)). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.

  17. Amylase activity of a yellow pigmented bacterium isolated from ...

    African Journals Online (AJOL)

    This study investigated the amylase activity of a yellow pigmented bacterium isolated from cassava wastes obtained from a dumpsite near a gari processing factory in Ibadan, Nigeria. Isolate was grown in nutrient broth containing 1% starch and then centrifuged at 5,000 rpm. Amylase activity was assayed using the DNSA ...

  18. Biosynthesis of silver nanoparticles by marine bacterium, Idiomarina ...

    Indian Academy of Sciences (India)

    In this paper, we report the intracellular synthesis of silver nanoparticles (SNPs) by the highly silver-tolerant marine bacterium, Idiomarina sp. PR58-8 on exposure to 5mM silver nitrate. SNPs were characterized by UV-visible spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission ...

  19. Non-obligate predatory bacterium Burkholderia casidae and uses thereof

    OpenAIRE

    2001-01-01

    A novel predator bacterium Burkholderia casidae is disclosed. The invention is directed to the isolation and use of Burkholderia casidae to control microbial diseases of plants. The genetic, biochemical and physiological characteristics of Burkholderia casidae are described. Biocontrol compositions comprising Burkholderia casidae, and antimicrobial compounds and antimicrobial preparations prepared from Burkholderia casidae are also disclosed, as are methods for accomplishing all of the forego...

  20. Non-obligate predatory bacterium burkholderia casidaeand uses thereof

    OpenAIRE

    1998-01-01

    A novel predator bacterium Burkholderia casidae is disclosed. The invention is directed to the isolation and use of Burkholderia casidae to control microbial diseases of plants. The genetic, biochemical and physiological characteristics of Burkholderia casidae are described. Biocontrol compositions comprising Burkholderia casidae, and antimicrobial compounds and antimicrobial preparations prepared from Burkholderia casidae are also disclosed, as are methods for accomplishing all of the forego...

  1. Gut bacterium of Dendrobaena veneta (Annelida: Oligochaeta) possesses antimycobacterial activity.

    Science.gov (United States)

    Fiołka, Marta J; Zagaja, Mirosław P; Piersiak, Tomasz D; Wróbel, Marek; Pawelec, Jarosław

    2010-09-01

    The new bacterial strain with antimycobacterial activity has been isolated from the midgut of Dendrobaena veneta (Annelida). Biochemical and molecular characterization of isolates from 18 individuals identified all as Raoultella ornithinolytica genus with 99% similarity. The bacterium is a possible symbiont of the earthworm D. veneta. The isolated microorganism has shown the activity against four strains of fast-growing mycobacteria: Mycobacterium butiricum, Mycobacterium jucho, Mycobacterium smegmatis and Mycobacterium phlei. The multiplication of the gut bacterium on plates with Sauton medium containing mycobacteria has caused a lytic effect. After the incubation of the cell free extract prepared from the gut bacterium with four strains of mycobacteria in liquid Sauton medium, the cells of all tested strains were deformed and divided to small oval forms and sometimes created long filaments. The effect was observed by the use of light, transmission and scanning microscopy. Viability of all examined species of mycobacteria was significantly decreased. The antimycobacterial effect was probably the result of the antibiotic action produced by the gut bacterium of the earthworm. The application of ultrafiltration procedure allowed to demonstrate that antimicrobial substance with strong antimycobacterial activity from bacterial culture supernatant, is a protein with the molecular mass above 100 kDa. Copyright 2010 Elsevier Inc. All rights reserved.

  2. Engineering a wild fast-growing Mycoplasma bacterium to generate ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2018-01-12

    Jan 12, 2018 ... To develop a fast growing CCPP vaccine for cheaper production and long term protection, cutting edge synthetic biotechnology tools will be used to delete harmful and nonessential genes from a fast growing bacterium isolated from wild goats. These genes will be replaced by CCPP protective vaccine ...

  3. Antagonistic bioactivity of an endophytic bacterium H-6

    African Journals Online (AJOL)

    GREGORY

    2010-09-13

    Sep 13, 2010 ... lower compared to P. capsici-inoculated and H-6-treated plants, which is an added advantage of the strain used as potential biocontrol agent in future. Key words: Endophytic bacterium, 16S rDNA gene, antagonistic activity, Huperzia serrata. INTRODUCTION. Soil-borne diseases are a serious concern in ...

  4. Control of magnetotactic bacterium in a micro-fabricated maze

    NARCIS (Netherlands)

    Khalil, I.S.M.; Pichel, Marc Philippe; Pichel, M.P.; Reefman, B.A.; Sardan Sukas, Ö.; Abelmann, Leon; Misra, Sarthak

    2013-01-01

    We demonstrate the closed-loop control of a magnetotactic bacterium (MTB), i.e., Magnetospirillum magnetotacticum, within a micro-fabricated maze using a magneticbased manipulation system. The effect of the channel wall on the motion of the MTB is experimentally analyzed. This analysis is done by

  5. Isolation and characterization of a new keratinolytic bacterium that ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-09-15

    Sep 15, 2009 ... These results suggest potential biotechnological applications of this bacterium that involve ... useful protein and amino acids, they have limited use as ... Protease-producing bacteria that formed clear haloes were selected. They were transferred subsequently at frequent intervals to feather meal broth.

  6. Antagonistic bioactivity of an endophytic bacterium H-6

    African Journals Online (AJOL)

    GREGORY

    2010-09-13

    Sep 13, 2010 ... growth in vitro of 6 plant pathogenic fungi, especially of Phytophthora capsici, Fusarium graminearumt ... Key words: Endophytic bacterium, 16S rDNA gene, antagonistic activity, Huperzia serrata. ..... Biological control of Phytophthora blight in red pepper (Capsicum annuum L.) using Bacillus subtilis.

  7. Rhodococcus opacus strain RW, a resorcinol-degrading bacterium ...

    African Journals Online (AJOL)

    The isolate is a rod-shaped bacterium that exhibited evolutionary relatedness with the genus Rhodococcus, as determined by phenotypic traits and physiological tests, and a 16S rRNA gene sequence similarity value of 99.6% to the closest Rhodococcus opacus strain. On the basis of these results isolate RW is proposed as ...

  8. IrrE, a global regulator of extreme radiation resistance in Deinococcus radiodurans, enhances salt tolerance in Escherichia coli and Brassica napus.

    Directory of Open Access Journals (Sweden)

    Jie Pan

    Full Text Available BACKGROUND: Globally, about 20% of cultivated land is now affected by salinity. Salt tolerance is a trait of importance to all crops in saline soils. Previous efforts to improve salt tolerance in crop plants have met with only limited success. Bacteria of the genus Deinococcus are known for their ability to survive highly stressful conditions, and therefore possess a unique pool of genes conferring extreme resistance. In Deinococcus radiodurans, the irrE gene encodes a global regulator responsible for extreme radioresistance. METHODOLOGY/PRINCIPAL FINDINGS: Using plate assays, we showed that IrrE protected E. coli cells against salt shock and other abiotic stresses such as oxidative, osmotic and thermal shocks. Comparative proteomic analysis revealed that IrrE functions as a switch to regulate different sets of proteins such as stress responsive proteins, protein kinases, glycerol-degrading enzymes, detoxification proteins, and growth-related proteins in E. coli. We also used quantitative RT-PCR to investigate expression of nine selected stress-responsive genes in transgenic and wild-type Brassica napus plants. Transgenic B. napus plants expressing the IrrE protein can tolerate 350 mM NaCl, a concentration that inhibits the growth of almost all crop plants. CONCLUSIONS: Expression of IrrE, a global regulator for extreme radiation resistance in D. radiodurans, confers significantly enhanced salt tolerance in both E. coli and B. napus. We thus propose that the irrE gene might be used as a potentially promising transgene to improve abiotic stress tolerances in crop plants.

  9. A novel C-terminal domain of RecJ is critical for interaction with HerA in Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Kaiying eCheng

    2015-11-01

    Full Text Available Homologous recombination (HR generates error-free repair products, which plays an important role in double strand break repair and replication fork rescue processes. DNA end resection, the critical step in HR, is usually performed by a series of nuclease/helicase. RecJ was identified as a 5’-3’ exonuclease involved in bacterial DNA end resection. Typical RecJ possesses a conserved DHH domain, a DHHA1 domain, and an oligonucleotide/oligosaccharide-binding (OB fold. However, RecJs from Deinococcus-Thermus phylum, such as Deinococcus radiodurans RecJ (DrRecJ, possess an extra C-terminal domain (CTD, of which the function has not been characterized. Here, we showed that a CTD-deletion of DrRecJ (DrRecJΔC could not restore drrecJ mutant growth and mitomycin C (MMC-sensitive phenotypes, indicating that this domain is essential for DrRecJ in vivo. DrRecJΔC displayed reduced DNA nuclease activity and DNA binding ability. Direct interaction was identified between DrRecJ-CTD and DrHerA, which stimulates DrRecJ nuclease activity by enhancing its DNA binding affinity. Moreover, DrNurA nuclease, another partner of DrHerA, inhibited the stimulation of DrHerA on DrRecJ nuclease activity by interaction with DrHerA. Opposing growth and MMC-resistance phenotypes between the recJ and nurA mutants were observed. A novel modulation mechanism among DrRecJ, DrHerA, and DrNurA was also suggested.

  10. Peoples of Africa, Topic 1. Africa South of the Sahara: A Program of Study for Secondary School Social Studies Students. (Teaching and Student Guides).

    Science.gov (United States)

    Carnegie-Mellon Univ., Pittsburgh, PA. Project Africa.

    This teaching guide and student text for Project Africa's curriculum program, "Africa South of the Sahara," deal with how four typical contemporary African peoples acquired their present way of life: (1) the Hausa of Northern Nigeria, (2) the Kung Bushmen of the Kalahari Desert, (3) the Mech'a Galla of Ethiopa, and (4) the Kikuyu of…

  11. A reward for patience and suffering – Ethnomycology and commodification of desert truffles among Sahrawi refugees and nomads of Western Sahara

    NARCIS (Netherlands)

    Volpato, G.; Rossi, D.; Dentoni, D.

    2013-01-01

    A Reward for Patience and Suffering: Ethnomycology and Commodification of Desert Truffles among Sahrawi Refugees and Nomads of Western Sahara. This paper reflects on the role of ethnobiological knowledge and practices for refugees’ agency by focusing on the use and commodification of desert truffles

  12. Implementation of Information Communication Technology in the Teaching/Learning Process for Sustainable Development of Adults in West Africa Sub Sahara Region

    Science.gov (United States)

    Nwobi, Anthonia; Ngozi, Ugwuoke; Rufina, Nwachukwu; Ogbonnaya, Kingsley A.

    2016-01-01

    This study examines the implementation of information technology in the teaching/learning process for sustainable development of adults in West Africa Sub Sahara Region (WASSR). Three research questions and two hypotheses guided the study. The population for the study was 3071 participants and instructors drawn from 10 education centres that were…

  13. ARCHAEOLOGICAL AND ENVIRONMENTAL CHANGES BETWEEN 9500 BP AND 4500 BP: A CONTRIBUTION FROM THE SAHARA TO UNDERSTAND EXPANDING DROUGHTS IN THE “GREAT MEDITERRANEAN”

    Directory of Open Access Journals (Sweden)

    E. A.A. Garcea

    2013-03-01

    Full Text Available The Sahara is more connected to the Mediterranean than often assumed and palynology, in particular, has provided evidence of past interrelations between the Mediterranean and the Sahara with pollen spectra from prehistoric Saharan deposits including Mediterranean taxa. In order to show human-environment relationships and populations’ strategies in response to changing environments, this paper presents a case study from the southern Sahara. This region offered a natural laboratory for the study of human/climate interaction as the range of environmental change extended from flood to drought, forcing people to cope with periodic environmental instability. When the tropical rainfall belt migrated northward, watertable outcropped in interdunal depressions and formed permanent lakes, which alternated with severe arid spells. As a case study, this paper presents the results of interdisciplinary investigations on climate changes, human adaptations and subsistence strategies at Gobero, in the southern Sahara of Niger. Gobero is a restricted archaeological area comprising 8 sites that surround the shores of a palaeolake. It was intermittently occupied between about 9500 cal years BP and 4500 BP. Due to alternating environmental conditions it could only be occupied at the beginning and at the end of the most humid periods.

  14. Computational study on ice growth inhibition of Antarctic bacterium antifreeze protein using coarse grained simulation

    OpenAIRE

    Nguyen, Hung; Le, Ly; Ho, Tu Bao

    2014-01-01

    Antarctic bacterium antifreeze proteins (AFPs) protect and support the survival of cold-adapted organisms by binding and inhibiting the growth of ice crystals. The mechanism of the anti-freezing process in a water environment at low temperature of Antarctic bacterium AFPs remains unclear. In this research, we study the effects of Antarctic bacterium AFPs by coarse grained simulations solution at a temperature range from 262 to 273K. The results indicated that Antarctic bacterium AFPs were ful...

  15. Phylogeny of North African Agama lizards (Reptilia: Agamidae) and the role of the Sahara desert in vertebrate speciation.

    Science.gov (United States)

    Gonçalves, Duarte V; Brito, José C; Crochet, Pierre-André; Geniez, Philippe; Padial, José M; Harris, D James

    2012-09-01

    The origin of Saharan biodiversity is poorly understood, in part because the geological and paleoclimatic events that presumably shaped species diversity are still controversial, but also because few studies have explored causal explanations for the origin of Saharan diversity using a phylogenetic framework. Here, we use mtDNA (16S and ND4 genes) and nDNA (MC1R and CMOS genes) to infer the relationships and biogeographic history of North African agamas (genus Agama). Agamas are conspicuous, diverse and abundant African lizards that also occur in the Saharan xeric and mesic environments. Our results revealed the presence of three Agama lineages in North Africa: one Afrotropical, one Sahelo-Saharan, and one broadly distributed in North Africa and mainly Saharan. Southern Mauritania contains the highest known diversity, with all three lineages present. Results suggest that agamas colonized the Sahara twice, but only one lineage was able to radiate and diversify there. Species in the Saharan lineage are mostly allopatric, and their splitting, genetic diversity and distribution are greatly explained by mountain ranges. One species in this lineage has colonized the Mediterranean climatic zone (A. impalearis), and another one the Sahel savannah (A. boueti). The other lineage to colonize the Sahara corresponds to A. boulengeri, an eminently Sahelian species that also inhabits Saharan mountain ranges in Mauritania and Mali. Phylogenetic analyses indicate that allopatric montane populations within some currently recognized species are also genetically divergent. Our study therefore concludes that vicariant speciation is a leading motor of species diversification in the area: Inside the Sahara, associated to mountain-ranges isolated by dune seas and bare plains; outside, associated to less harsh climates to the North and South. Paleoclimatic oscillations are suggested as causal explanations of the vicariant distribution and origin of species. Agamas are thought to have

  16. The evolution of the 87Sr/86Sr in the Dead Sea brine: from the Sedom lagoon to Sahara dusts

    Science.gov (United States)

    Stein, Mordechai

    2016-04-01

    The history of water-bodies in the Dead Sea brines commenced with the intrusion of the Sedom lagoon, possibly in the late Neogene and continued with the development of hypersaline and freshwater lakes (e.g. the modern Dead Sea and Sea of Galilee). 87Sr/86Sr ratios in these water-bodies decreased over the past ~ 5-6 Ma from 0.7087-0.7084 in salts deposited in the Sedom lagoon to ~ 0.7080 in modern Dead Sea brine. The 87Sr/86Sr ratios in the salts deposited from Sedom lagoon are significantly lower than those of the contemporaneous late Miocene seawater (~0.709). This difference was attributed to modification of the 87Sr/86Sr ratio in the Sedom lagoon solution by influx of Ca-chloride brines. The brines, in turn were formed by dolomitization of marine limestones of the DSR Cretaceous wall rocks (87Sr/86Sr ~ 0.7075) by the ingressing evaporated seawaters (Stein et al., 2000). After the disconnection of the Sedom lagoon from the open sea freshwater filled the lakes that occupied the Dead Sea basin. The freshwater influx modified the strontium isotope and chemical composition of the brine and provided bicarbonate and sulfate to the lake that led the precipitation of primary aragonite and gypsum. Freshwater that currently enter the lake are characterize by 87Sr/86Sr ~ 0.7081, significantly higher than the Cretaceous carbonates. Settled dust that deposits on the Judea Mountains is composed of calcite and quartz grains and is characterized by 87Sr/86Sr ratios ~ 0.7084. It appears that significant amounts of the strontium that entered the lakes with the freshwater originated from dissolution of the dust calcites. Large amounts of dust were transported from the Sahara desert to the Dead Sea watershed during glacial periods when the Sahara was dry and sea-level was low. The source of the detrital calcites however, is not known. They could be derived from dry paleo-lakes in the Sahara that were previously filled by waters that retained the required strontium isotope

  17. South Asian Heart Risk Assessment (SAHARA): Randomized Controlled Trial Design and Pilot Study

    Science.gov (United States)

    Samaan, Zainab; Schulze, Karleen M; Middleton, Catherine; Irvine, Jane; Joseph, Phillip; Mente, Andrew; Shah, Baiju R; Pare, Guillaume; Desai, Dipika

    2013-01-01

    Background People of South Asian origin suffer a high burden of premature myocardial infarction (MI). South Asians form a growing proportion of the Canadian population and preventive strategies to mitigate the risk of MI in this group are needed. Prior studies have shown that multimedia interventions are effective and feasible in inducing health behavior changes among the obese, smokers, and among those who are sedentary. Objective Among at-risk South Asians living in Canada, our objectives are to determine: (1) the feasibility of a culturally tailored multimedia intervention to induce positive behavioral changes associated with reduced MI risk factors, and (2) the effectiveness and acceptability of information communicated by individualized MI and genetic risk score (GRS) reports. Methods The South Asian HeArt Risk Assessment (SAHARA) pilot study enrolled 367 individuals of South Asian origin recruited from places of worship and community centers in Ontario, Canada. MI risk factors including the 9p21 genetic variant status were provided to all participants after the baseline visit. Participants were randomly allocated to receive a multimedia intervention or control. The intervention group selected health goals and received personalized health messages to promote adherence to their selected goals. After 6 months, all participants had their MI risk factors repeated. The methods and results of this study are reported based on the CONSORT-EHEALTH guidelines. Results The mean age of participants was 53.8 years (SD 11.4), 52.0% (191/367) were women, and 97.5% (358/367) were immigrants to Canada. The mean INTERHEART risk score was 13.0 (SD 5.8) and 73.3% (269/367) had one or two copies of the risk allele for the 9p21 genetic variant. Both the intervention and control groups made some progress in health behavior changes related to diet and physical activity over 6 months. Participants reported that their risk score reports motivated behavioral changes, although half of

  18. Dust and biological aerosols from the Sahara and Asia influence precipitation in the western U.S.

    Science.gov (United States)

    Creamean, Jessie M; Suski, Kaitlyn J; Rosenfeld, Daniel; Cazorla, Alberto; DeMott, Paul J; Sullivan, Ryan C; White, Allen B; Ralph, F Martin; Minnis, Patrick; Comstock, Jennifer M; Tomlinson, Jason M; Prather, Kimberly A

    2013-03-29

    Winter storms in California's Sierra Nevada increase seasonal snowpack and provide critical water resources and hydropower for the state. Thus, the mechanisms influencing precipitation in this region have been the subject of research for decades. Previous studies suggest Asian dust enhances cloud ice and precipitation, whereas few studies consider biological aerosols as an important global source of ice nuclei (IN). Here, we show that dust and biological aerosols transported from as far as the Sahara were present in glaciated high-altitude clouds coincident with elevated IN concentrations and ice-induced precipitation. This study presents the first direct cloud and precipitation measurements showing that Saharan and Asian dust and biological aerosols probably serve as IN and play an important role in orographic precipitation processes over the western United States.

  19. The Sources of Moisture in the Sand Dunes – The Example of the Western Sahara Dune Field

    Directory of Open Access Journals (Sweden)

    Żmudzka Elwira

    2014-09-01

    Full Text Available Climatic and meteorological conditions may limit the aeolian transport within barchans. An explanation of that issue was the main goal of the investigation held in Western Sahara dune fields located around Tarfaya and Laâyoune. Particular attention was paid to the factors causing the moisture content rising of the sand dune surface layer, which could influence the wind threshold shear velocity in the aeolian transport. The wetted surface layer of sand, when receiving moisture from precipitation or suspensions, reduces the aeolian transport, even in case of wind velocity above 4-5 m s-1. Fog and dew condensation does not affect the moisture of deeper sand layers, what occurs after rainfall.

  20. [Severe keratomycosis due to Fusarium solani induced by a telluric foreign body: About a case in moroccan Sahara].

    Science.gov (United States)

    Er-Rami, M; Souhail, H; Lemkhente, Z; El Mellouki, W; Lmimouni, B

    2011-09-01

    We report a case of severe keratitis due to Fusarium solani in a young man in the Sahara in Morocco where the climate is arid. This patient reported had a grain of sand in his right eye for a week after a sandstorm. On admission he had a corneal abscess. Despite rapid diagnosis and initiation of treatment with available antifungal drugs: amphotericin B and natamycin eye drops, the prognosis worsened and led to the enucleation of the right eye. Faced with a suspected eye infection after a microtrauma caused by grains of sand carried by a sandstorm, it is important to take biological samples to search for fungal infections among other. It is also important to have new triazole antifungal drugs available to treat ocular mycosis rapidly and effectively. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  1. África al sur del Sahara: conflictos y degradación ambiental en el Sahel

    Directory of Open Access Journals (Sweden)

    Stella Maris Shmite

    2015-08-01

    Full Text Available The Sahel is a region located south of the Sahara Desert that is affected by a combination of problems, including droughts, soil degradation, demographic pressure, malnutrition, poverty, migration, conflicts, and refugees, among others. In this region, environmental changes strongly impact sociocultural, political and economic dimensions. These changes also act as multipliers of social tensions and stimulate political instability. The goal of this article is to identify these problems and analyze environmental variables to address the territorial context. This study seeks to interpret a range of sources, such as cartographical data, statistics and academic publications, that may allow for not only the complex network of persisting conflicts but also emerging conflicts in this cross-border African region to be comprehensively visualized and understood.

  2. Ethnomycological survey of traditional usage and indigenous knowledge on desert truffles among the native Sahara Desert people of Algeria.

    Science.gov (United States)

    Bradai, Lyès; Neffar, Souad; Amrani, Khaled; Bissati, Samia; Chenchouni, Haroun

    2015-03-13

    Desert truffles are edible hypogeous fungi, highly appreciated by the inhabitants of hot-desert settlements. Native Saharan people use truffles for food, promoting tourism, increasing fertility, and treatment of eye diseases and fatigue. This study consists of a cross-sectional survey focusing on the knowledge, use and ethnomycological practices of desert truffles among the native people of the Algerian Northern Sahara. The study was conducted through direct interviews with 60 truffle-hunters in the regions of Ouargla and Ghardaia. Three species were harvested and consumed by the surveyed subjects: Terfezia claveryi was the most appreciated and most expensive species, followed by Terfezia areanaria moderately preferred, then Tirmania nivea the least appreciated and least expensive. Among the 60 interviewees, 90% rely on the abundance of symbiotic plants (Helianthemum lippii) to harvest truffles, 65% begin harvesting from mid-February to March, after rains of the autumn (38%) and winter (36%), particularly in the Wadi beds (37%) and Daya landscapes (32%). Interviewees harvested truffles mainly for home consumption; however 26.7% sell any harvest surplus, and of those only 15% generate significant revenue from this source, and 73% considered the sale of desert truffles to have low financial value. Desert truffles are used in traditional medicine, especially against eye infections (22%), weakness (19%) and to promote male fertility (19%). In the case of desert truffles for consumption, the surveyed population preferred to prepare the truffles with couscous and meat, or in porridge. Respondents used price as the main criterion for deciding whether to purchase desert truffles. The surveyed trufflers use the knowledge passed from one generation to the next to help ensure a good harvest of truffles during each foray into the desert. Our findings highlight the various uses of truffles in the Sahara Desert, and how these relate to the lifestyle of local people. Copyright

  3. Mineral Dust Analysis and Application in Refining Source Region Information for the Sahara and East Asia Deserts

    Science.gov (United States)

    Reid, E. A.; Reid, J. S.; Westphal, D.; Cliff, S.; Dunlap, M.

    2002-12-01

    The study of transported mineral dust aerosols relies heavily on simplified dust source region parameters. Source regions are broadly defined by soil class and expected erodibility, factors which continuously changes with land use and climate conditions. Mineral dust particles may undergo numerous cycles of deposition and re-entrainment prior to collection and analysis. Using the Sahara Desert and the East Asia deserts as test cases, we investigate the possibility of retrieving source information from receptor sites through single particle and bulk analyses of collected aerosol particles. In June and July of 2000, Saharan mineral dust aerosols transported across the Atlantic Ocean to Puerto Rico were collected for bulk and single particle chemical and morphological analyses. The Puerto Rico Dust Experiment, (PRIDE), involved sampling aerosols upwind of the islands at various altitudes in the marine boundary layer (MBL) and Saharan Air Layer (SAL) via a Navajo research aircraft. A surface site included a Davis Rotating Drum (DRUM) cascade impactor to size segregate the aerosols into eight stages, from 12 to 0.1 micrometers, with four-hour time resolution. In April of 2001, size segregated Asian mineral dust aerosols were collected by three hour resolution DRUM samplers at surface sites in Cheju, Taiwan, for bulk chemical analysis. The aircraft samples and selected DRUM samples were subjected to single particle analysis by scanning electron microscopy (SEM) for particle morphology, and by Energy Dispersive Analysis with X-rays (EDAX) to derive elemental ratios of key soil elements. The DRUM samples were subjected to X-Ray Fluorescence (XRF) to derive bulk elemental composition for elements Al though Zn. Cluster and principal component analysis of the data derived statistically significant particle groupings. By including particle morphology data, and using ternary analyses, derivation of additional source information was possible. Particle compositions

  4. A Streamlined Strategy for Biohydrogen Production with an Alkaliphilic Bacterium

    Energy Technology Data Exchange (ETDEWEB)

    Elias, Dwayne A [ORNL; Wall, Judy D. [University of Missouri; Mormile, Dr. Melanie R. [Missouri University of Science and Technology; Begemann, Matthew B [University of Wisconsin, Madison

    2012-01-01

    Biofuels are anticipated to enable a shift from fossil fuels for renewable transportation and manufacturing fuels, with biohydrogen considered attractive since it could offer the largest reduction of global carbon budgets. Currently, biohydrogen production remains inefficient and heavily fossil fuel-dependent. However, bacteria using alkali-treated biomass could streamline biofuel production while reducing costs and fossil fuel needs. An alkaliphilic bacterium, Halanaerobium strain sapolanicus, is described that is capable of biohydrogen production at levels rivaling neutrophilic strains, but at pH 11 and hypersaline conditions. H. sapolanicus ferments a variety of 5- and 6- carbon sugars derived from hemicellulose and cellulose including cellobiose, and forms the end products hydrogen and acetate. Further, it can also produce biohydrogen from switchgrass and straw pretreated at temperatures far lower than any previously reported and in solutions compatible with growth. Hence, this bacterium can potentially increase the efficiency and efficacy of biohydrogen production from renewable biomass resources.

  5. Molecular pathogenesis of the obligate intracellular bacterium Coxiella burnetii

    Science.gov (United States)

    van Schaik, Erin J.; Chen, Chen; Mertens, Katja; Weber, Mary M.; Samuel, James E.

    2014-01-01

    The agent of Q fever, Coxiella burnetii, is an obligate intracellular bacterium that causes acute and chronic infections. The study of C. burnetii pathogenesis has benefited from two recent fundamental advances: improved genetic tools and the ability to grow the bacterium in extracellular media. In this Review, we describe how these recent advances have improved our understanding of C. burnetii invasion and host cell modulation, including the formation of replication-permissive Coxiella-containing vacuoles. Furthermore, we describe the Dot/Icm (defect in organelle trafficking/intracellular multiplication) system, which is used by C. burnetii to secrete a range of effector proteins into the host cell, and we discuss the role of these effectors in remodelling the host cell. PMID:23797173

  6. Delta8(14)-steroids in the bacterium Methylococcus capsulatus.

    Science.gov (United States)

    Bouvier, P; Rohmer, M; Benveniste, P; Ourisson, G

    1976-01-01

    The 4,4-dimethyl and 4alpha-methyl sterols of the bacterium Methylococcus capsulatus were identified as 4,4-dimethyl- and 4alpha-methyl-5alpha-cholest-8(14)-en-3beta-ol and 4,4-dimethyl- and 4alpha-methyl-5alpha-cholesta-8(14),24-dien-3beta-ol. Sterol biosynthesis is blocked at the level of 4alpha-methyl delta8(14)-sterols. PMID:999649

  7. Initiation of chromosomal replication in predatory bacterium Bdellovibrio bacteriovorus

    Directory of Open Access Journals (Sweden)

    Lukasz Makowski

    2016-11-01

    Full Text Available Bdellovibrio bacteriovorus is a small Gram-negative predatory bacterium that attacks other Gram-negative bacteria, including many animal, human, and plant pathogens. This bacterium exhibits a peculiar biphasic life cycle during which two different types of cells are produced: non-replicating highly motile cells (the free-living phase and replicating cells (the intracellular-growth phase. The process of chromosomal replication in B. bacteriovorus must therefore be temporally and spatially regulated to ensure that it is coordinated with cell differentiation and cell cycle progression. Recently, B. bacteriovorus has received considerable research interest due to its intriguing life cycle and great potential as a prospective antimicrobial agent. Although we know that chromosomal replication in bacteria is mainly regulated at the initiation step, no data exists about this process in B. bacteriovorus. We report the first characterization of key elements of initiation of chromosomal replication – DnaA protein and oriC region from the predatory bacterium, B. bacteriovorus. In vitro studies using different approaches demonstrate that the B. bacteriovorus oriC (BdoriC is specifically bound and unwound by the DnaA protein. Sequence comparison of the DnaA-binding sites enabled us to propose a consensus sequence for the B. bacteriovorus DnaA box (5’-NN(A/TTCCACA-3’. Surprisingly, in vitro analysis revealed that BdoriC is also bound and unwound by the host DnaA proteins (relatively distantly related from B. bacteriovorus. We compared the architecture of the DnaA–oriC complexes (orisomes in homologous (oriC and DnaA from B. bacteriovorus and heterologous (BdoriC and DnaA from prey, E. coli or P. aeruginosa systems. This work provides important new entry points toward improving our understanding of the initiation of chromosomal replication in this predatory bacterium.

  8. Heavy Metal Induced Antibiotic Resistance in Bacterium LSJC7

    OpenAIRE

    Songcan Chen; Xiaomin Li; Guoxin Sun; Yingjiao Zhang; Jianqiang Su; Jun Ye

    2015-01-01

    Co-contamination of antibiotics and heavy metals prevails in the environment, and may play an important role in disseminating bacterial antibiotic resistance, but the selective effects of heavy metals on bacterial antibiotic resistance is largely unclear. To investigate this, the effects of heavy metals on antibiotic resistance were studied in a genome-sequenced bacterium, LSJC7. The results showed that the presence of arsenate, copper, and zinc were implicated in fortifying the resistance of...

  9. Mutation of Bacterium Vibrio gazogenes for Selective Preparation of Colorants

    OpenAIRE

    Alihosseini, Farzaneh; Lango, Jozsef; Ju, Kou-San; Hammock, Bruce D.; Sun, Gang

    2010-01-01

    A novel marine bacterium strain effectively produced prodiginine type pigments. These colorants could dye wool, silk and synthetic fabrics such as polyester and polyacrylic and also show antibacterial properties against Escherichia coli and Staphylococcus aureus bacteria on the dyed products. Methyl nitrosoguanidine was used as a mutation agent to increase the genetic diversity and the production yield of the bacteria of the family of Vibrio gazogenes. The analysis of the mutated samples show...

  10. Salt-inducible promoter derivable from a lactic acid bacterium, and its use in a lactic acid bacterium for production of a desired protein

    NARCIS (Netherlands)

    Sanders, Jan Willem; Kok, Jan; Venema, Gerard; Ledeboer, Adrianus Marinus

    1998-01-01

    The invention provides a salt-inducible promoter present in SEQ ID NO: 10 and derivable from a lactic acid bacterium in isolation from the coding sequence normally controlled by said promoter in a wild-type lactic acid bacterium, with modifications and important parts thereof. Also provided are a

  11. A study of the relict fish fauna of northern Chad, with the first records of a polypterid and a poeciliid in the Sahara desert.

    Science.gov (United States)

    Trape, Sébastien

    2013-01-01

    Seventeen species and sub-species of fishes belonging to four families (Cyprinidae, Clariidae, Aplocheilidae, Cichlidae) were known to occur in perennial bodies of water in the Sahara desert. The study of fishes collected in Lake Boukou near Ounianga Serir (Borkou, northern Chad) shows, for the first time, the occurrence in the Sahara desert of relict populations of Polypterus senegalus (Polypteridae) and Poropanchax normani (Poeciliidae). The Cichlidae Tilapia zilli was also collected in this lake. With these new records, the relict fish fauna currently known in lakes and gueltas of the Borkou plateaus comprises six species. In the Ennedi Mountains, where the specific status of Barbus populations was unclear, B. macrops was collected in Bachikere guelta. The toad Amietophrynus regularis was collected in Ounianga Kebir. Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  12. Deinococcus radiodurans Toxin-Antitoxin MazEF-dr Mediates Cell Death in Response to DNA Damage Stress.

    Science.gov (United States)

    Li, Tao; Weng, Yulan; Ma, Xiaoqiong; Tian, Bing; Dai, Shang; Jin, Ye; Liu, Mengjia; Li, Jiulong; Yu, Jiangliu; Hua, Yuejin

    2017-01-01

    Here we identified a functional MazEF-dr system in the exceptionally stress-resistant bacterium D. radiodurans. We showed that overexpression of the toxin MazF-dr inhibited the growth of Escherichia coli. The toxic effect of MazF-dr was due to its sequence-specific endoribonuclease activity on RNAs containing a consensus 5'ACA3', and it could be neutralized by MazE-dr. The MazF-dr showed a special cleavage preference for the nucleotide present before the ACA sequence with the order by U>A>G>C. MazEF-dr mediated the death of D. radiodurans cells under sub-lethal dose of stresses. The characteristics of programmed cell death (PCD) including membrane blebbing, loss of membrane integrity and cytoplasm condensation occurred in a fraction of the wild-type population at sub-lethal concentration of the DNA damaging agent mitomycin C (MMC); however, a MazEF-dr mutation relieved the cell death, suggesting that MazEF-dr mediated cell death through its endoribonuclease activity in response to DNA damage stress. The MazEF-dr-mediated cell death of a fraction of the population might serve as a survival strategy for the remaining population of D. radiodurans under DNA damage stress.

  13. Deinococcus radiodurans Toxin–Antitoxin MazEF-dr Mediates Cell Death in Response to DNA Damage Stress

    Science.gov (United States)

    Li, Tao; Weng, Yulan; Ma, Xiaoqiong; Tian, Bing; Dai, Shang; Jin, Ye; Liu, Mengjia; Li, Jiulong; Yu, Jiangliu; Hua, Yuejin

    2017-01-01

    Here we identified a functional MazEF-dr system in the exceptionally stress-resistant bacterium D. radiodurans. We showed that overexpression of the toxin MazF-dr inhibited the growth of Escherichia coli. The toxic effect of MazF-dr was due to its sequence-specific endoribonuclease activity on RNAs containing a consensus 5′ACA3′, and it could be neutralized by MazE-dr. The MazF-dr showed a special cleavage preference for the nucleotide present before the ACA sequence with the order by U>A>G>C. MazEF-dr mediated the death of D. radiodurans cells under sub-lethal dose of stresses. The characteristics of programmed cell death (PCD) including membrane blebbing, loss of membrane integrity and cytoplasm condensation occurred in a fraction of the wild-type population at sub-lethal concentration of the DNA damaging agent mitomycin C (MMC); however, a MazEF-dr mutation relieved the cell death, suggesting that MazEF-dr mediated cell death through its endoribonuclease activity in response to DNA damage stress. The MazEF-dr-mediated cell death of a fraction of the population might serve as a survival strategy for the remaining population of D. radiodurans under DNA damage stress. PMID:28798741

  14. Deinococcus radiodurans Toxin–Antitoxin MazEF-dr Mediates Cell Death in Response to DNA Damage Stress

    Directory of Open Access Journals (Sweden)

    Tao Li

    2017-07-01

    Full Text Available Here we identified a functional MazEF-dr system in the exceptionally stress-resistant bacterium D. radiodurans. We showed that overexpression of the toxin MazF-dr inhibited the growth of Escherichia coli. The toxic effect of MazF-dr was due to its sequence-specific endoribonuclease activity on RNAs containing a consensus 5′ACA3′, and it could be neutralized by MazE-dr. The MazF-dr showed a special cleavage preference for the nucleotide present before the ACA sequence with the order by U>A>G>C. MazEF-dr mediated the death of D. radiodurans cells under sub-lethal dose of stresses. The characteristics of programmed cell death (PCD including membrane blebbing, loss of membrane integrity and cytoplasm condensation occurred in a fraction of the wild-type population at sub-lethal concentration of the DNA damaging agent mitomycin C (MMC; however, a MazEF-dr mutation relieved the cell death, suggesting that MazEF-dr mediated cell death through its endoribonuclease activity in response to DNA damage stress. The MazEF-dr-mediated cell death of a fraction of the population might serve as a survival strategy for the remaining population of D. radiodurans under DNA damage stress.

  15. Genetic analysis of Rhipicephalus sanguineus sensu lato ticks parasites of dogs in Africa north of the Sahara based on mitochondrial DNA sequences.

    Science.gov (United States)

    Chitimia-Dobler, Lidia; Langguth, Johanna; Pfeffer, Martin; Kattner, Simone; Küpper, Thomas; Friese, Daniela; Dobler, Gerhard; Guglielmone, Alberto A; Nava, Santiago

    2017-05-30

    The aim of this work was to determine the evolutionary relationship among tick populations of Rhipicephalus sanguineus sensu lato distributed in Africa north of the Sahara and different lineages of R. sanguineus s.l. distributed in different regions of Sub-Saharan Africa, America and Europe through the analysis of DNA sequences of two mitochondrial genes. One hundred and thirty six 16S rRNA gene sequences and twenty-seven 12S rRNA gene sequences of R. sanguineus s.l. were analyzed. Phylogenetic analyses were performed including different lineages of R. sanguineus s.l. from America, Europe and Africa, and species belonging to the R. sanguineus group as Rhipicephalus camicasi, Rhipicephalus guilhoni, Rhipicephalus sulcatus, Rhipicephalus rossicus, Rhipicephalus pusillus, Rhipicephalus turanicus and Rhipicephalus leporis. At least two different lineages of R. sanguineus s.l. are living in sympatry in Africa north of the Sahara. One of these mitochondrial lineages belongs to the same evolutionary entity that R. sanguineus s.l. from tropical areas of America, R. sanguineus s.l. from Sub-Saharan Africa, R. camicasi and R. guilhoni. The other mitochondrial lineage of R. sanguineus s.l. present in Africa north of the Sahara is phylogenetically associated to R. sanguineus s.l. ticks from southeastern Europe (Romania, Turkey and Greece). Both evolutionary entities are clearly different to the evolutionary entity formed by R. sanguineus s.l. from western Europe and temperate areas of America. Thus, the name R. sanguineus s.s. cannot be assigned to any of the two evolutionary entities present in Africa north of the Sahara. The taxonomic status of these taxa will remain unresolved until new lines of evidence become available to complement the current results based on mitochondrial DNA. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. 'Everybody knows', but the rest of the world: the case of a caterpillar-borne reproductive loss syndrome in dromedary camels observed by Sahrawi pastoralists of Western Sahara.

    Science.gov (United States)

    Volpato, Gabriele; Di Nardo, Antonello; Rossi, Davide; Saleh, Saleh M Lamin; Broglia, Alessandro

    2013-01-10

    The traditional knowledge of local communities throughout the world is a valuable source of novel ideas and information to science. In this study, the ethnoveterinary knowledge of Sahrawi pastoralists of Western Sahara has been used in order to put forward a scientific hypothesis regarding the competitive interactions between camels and caterpillars in the Sahara ecosystem. Between 2005 and 2009, 44 semi-structured interviews were conducted with Sahrawi pastoralists in the territories administered by the Sahrawi Arab Democratic Republic, Western Sahara, using a snow-ball sampling design. Sahrawi pastoralists reported the existence of a caterpillar-borne reproductive loss syndrome, known locally as duda, affecting their camels. On the basis of Sahrawi knowledge about duda and of a thorough literature review, we built the hypothesis that: 1) caterpillars of the family Lasiocampidae (genera Lasiocampa, Psilogaster, or Streblote) have sudden and rare outbreaks on Acacia treetops in the Western Sahara ecosystem after heavy rainfall; 2) during these outbreaks, camels ingest the caterpillars while browsing; 3) as a consequence of this ingestion, pregnant camels have sudden abortions or give birth to weaklings. This hypothesis was supported by inductive reasoning built on circumstantiated evidence and analogical reasoning with similar syndromes reported in mares in the United States and Australia. The possible existence of a caterpillar-borne reproductive loss syndrome among camels has been reported for the first time, suggesting that such syndromes might be more widespread than what is currently known. Further research is warranted to validate the reported hypothesis. Finally, the importance of studying folk livestock diseases is reinforced in light of its usefulness in revealing as yet unknown biological phenomena that would deserve further investigation.

  17. Chitin utilization by the insect-transmitted bacterium Xylella fastidiosa.

    Science.gov (United States)

    Killiny, Nabil; Prado, Simone S; Almeida, Rodrigo P P

    2010-09-01

    Xylella fastidiosa is an insect-borne bacterium that colonizes xylem vessels of a large number of host plants, including several crops of economic importance. Chitin is a polysaccharide present in the cuticle of leafhopper vectors of X. fastidiosa and may serve as a carbon source for this bacterium. Biological assays showed that X. fastidiosa reached larger populations in the presence of chitin. Additionally, chitin induced phenotypic changes in this bacterium, notably increasing adhesiveness. Quantitative PCR assays indicated transcriptional changes in the presence of chitin, and an enzymatic assay demonstrated chitinolytic activity by X. fastidiosa. An ortholog of the chitinase A gene (chiA) was identified in the X. fastidiosa genome. The in silico analysis revealed that the open reading frame of chiA encodes a protein of 351 amino acids with an estimated molecular mass of 40 kDa. chiA is in a locus that consists of genes implicated in polysaccharide degradation. Moreover, this locus was also found in the genomes of closely related bacteria in the genus Xanthomonas, which are plant but not insect associated. X. fastidiosa degraded chitin when grown on a solid chitin-yeast extract-agar medium and grew in liquid medium with chitin as the sole carbon source; ChiA was also determined to be secreted. The gene encoding ChiA was cloned into Escherichia coli, and endochitinase activity was detected in the transformant, showing that the gene is functional and involved in chitin degradation. The results suggest that X. fastidiosa may use its vectors' foregut surface as a carbon source. In addition, chitin may trigger X. fastidiosa's gene regulation and biofilm formation within vectors. Further work is necessary to characterize the role of chitin and its utilization in X. fastidiosa.

  18. Liver abscess associated with an oral flora bacterium Streptococcus anginosus

    Directory of Open Access Journals (Sweden)

    Hava Yılmaz

    2012-03-01

    Full Text Available Viridans group Streptococcus, a bacterium of the oral flora has a low-virulence and rarely causes liver abscess. A 40-yearoldmale patient was admitted to the hospital complaining of high fever and malaise. A physical examination revealedpoor oral hygiene; there were caries on many teeth, and he had hepatomegaly. A hepatic abscess was identified inhis abdominal tomography. Streptococcus anginosus was isolated from the drainage material, and the bile ducts werenormal in his MRI cholangiography. An immunocompetent case of liver abscess caused by Streptococcus anginosusoriginated most probably from oral flora is presented here. J Microbiol Infect Dis 2012; 2(1:33-35

  19. Factors Affecting Zebra Mussel Kill by the Bacterium Pseudomonas fluorescens

    Energy Technology Data Exchange (ETDEWEB)

    Daniel P. Molloy

    2004-02-24

    The specific purpose of this research project was to identify factors that affect zebra mussel kill by the bacterium Pseudomonas fluorescens. Test results obtained during this three-year project identified the following key variables as affecting mussel kill: treatment concentration, treatment duration, mussel siphoning activity, dissolved oxygen concentration, water temperature, and naturally suspended particle load. Using this latter information, the project culminated in a series of pipe tests which achieved high mussel kill inside power plants under once-through conditions using service water in artificial pipes.

  20. A deep-sea bacterium with unique nitrifying property

    Digital Repository Service at National Institute of Oceanography (India)

    Ram, A.; LokaBharathi, P.A.; Nair, S.; Chandramohan, D.

    cember 2000 A deep - sea bacterium with unique n i trifying property A. S. Pradeep Ram, P. A. Loka Bharathi*, Shanta Nair and D. Chandramohan Department of Microbiology, National Institute of Oceanography, Dona Paula, Goa 403 004...) or sodium nitrite at 0.5 mM (final concentration) as e n ergy source and incubated for a period of 45 days at < 10?C. The colonies were enumerated and expressed as colony for m ing units (cfu) per gram dry weight sediment. Repre - sentatives from...

  1. Modeling the synergistic antibacterial effects of honey characteristics of different botanical origins from the Sahara Desert of Algeria

    Directory of Open Access Journals (Sweden)

    Hadda eLAALLAM

    2015-11-01

    Full Text Available Background: Honey has multiple therapeutic properties due to its composition with diverse components.Objectives: This study aims to investigate the antimicrobial efficacy of Saharan honeys against bacterial pathogens, the variation of honey floral origins and its physicochemical characteristics.Materials and Methods: The antimicrobial activity of 32 samples of honey collected from the Algerian Sahara Desert was tested on four pathogenic bacteria; Bacillus subtilis, Clostridium perfringens, Escherichia coli and Staphylococcus aureus. The botanical origin of honeys and their physicochemical properties were determined and their combined antibacterial effects were modeled using a generalized linear mixed model (GLMM.Results: Out of the 32 study samples, 14 were monofloral and 18 were multifloral. The pollen density was on average 7.86 × 106 grains/10 g of honey, water content was 14.6%, electrical conductivity was 0.5 μS/cm, pH was 4.38±0 50, hydroxymethylfurfural content was 82 mg/kg of honey, total sugars = 83%, reducing sugars = 71%, and the concentration of proline = 525.5±550.2 mg/kg of honey. GLMM revealed that the antibacterial effect of honey varied significantly between bacteria and floral origins. This effect increased with increasing of water content and reducing sugars in honey, but it significantly decreased with increase of honey electrical conductivity. E. coli was the most sensitive species with an inhibition zone of 10.1±4.7 mm, while C. perfringens was the less sensitive with 3.9±5.4 mm. Honeys dominated by pollen of Fabaceae sp. were most effective with an overall antimicrobial activity equals to 13.5±4.7 mm.Conclusion: Saharan honeys, of certain botanical origins, have physicochemical and pollinic characteristics with relevant potential for antibacterial purposes. This encourages a more comprehensive characterization of honeys with in vivo and in vitro investigations.Keywords: Honey characterization; antibacterial effects

  2. Research Progress and Perspectives of Nitrogen Fixing Bacterium, Gluconacetobacter diazotrophicus, in Monocot Plants

    Directory of Open Access Journals (Sweden)

    N. Eskin

    2014-01-01

    Full Text Available Gluconacetobacter diazotrophicus is a nitrogen fixing bacterium originally found in monocotyledon sugarcane plants in which the bacterium actively fixes atmosphere nitrogen and provides significant amounts of nitrogen to plants. This bacterium mainly colonizes intercellular spaces within the roots and stems of plants and does not require the formation of the complex root organ like nodule. The bacterium is less plant/crop specific and indeed G. diazotrophicus has been found in a number of unrelated plant species. Importantly, as the bacterium was of monocot plant origin, there exists a possibility that the nitrogen fixation feature of the bacterium may be used in many other monocot crops. This paper reviews and updates the research progress of G. diazotrophicus for the past 25 years but focuses on the recent research development.

  3. In situ determination of manganese(II) speciation in Deinococcus radiodurans by high magnetic field EPR: detection of high levels of Mn(II) bound to proteins.

    Science.gov (United States)

    Tabares, Leandro C; Un, Sun

    2013-02-15

    High magnetic field high frequency electron paramagnetic resonance techniques were used to measure in situ Mn(II) speciation in Deinococcus radiodurans, a radiation-resistant bacteria capable of accumulating high concentrations of Mn(II). It was possible to identify and quantify the evolution of Mn(II) species in intact cells at various stages of growth. Aside from water, 95-GHz high field electron nuclear double resonance showed that the Mn(II) ions are bound to histidines and phosphate groups, mostly from fructose-1,6-bisphosphate but also inorganic phosphates and nucleotides. During stationary growth phase, 285-GHz continuous wave EPR measurements showed that histidine is the most common ligand to Mn(II) and that significant amounts of cellular Mn(II) in D. radiodurans are bound to peptides and proteins. As much as 40% of the total Mn(II) was in manganese superoxide dismutase, and it is this protein and not smaller manganese complexes, as has been suggested recently, that is probably the primary defense against superoxide.

  4. PprM is necessary for up-regulation of katE1, encoding the major catalase of Deinococcus radiodurans, under unstressed culture conditions.

    Science.gov (United States)

    Jeong, Sun-Wook; Seo, Ho Seong; Kim, Min-Kyu; Choi, Jong-Il; Lim, Heon-Man; Lim, Sangyong

    2016-06-01

    Deinococcus radiodurans is a poly-extremophilic organism, capable of tolerating a wide variety of different stresses, such as gamma/ultraviolet radiation, desiccation, and oxidative stress. PprM, a cold shock protein homolog, is involved in the radiation resistance of D. radiodurans, but its role in the oxidative stress response has not been investigated. In this study, we investigated the effect of pprM mutation on catalase gene expression. pprM disruption decreased the mRNA and protein levels of KatE1, which is the major catalase in D. radiodurans, under normal culture conditions. A pprM mutant strain (pprM MT) exhibited decreased catalase activity, and its resistance to hydrogen peroxide (H2O2) decreased accordingly compared with that of the wild-type strain. We confirmed that RecG helicase negatively regulates katE1 under normal culture conditions. Among katE1 transcriptional regulators, the positive regulator drRRA was not altered in pprM (-), while the negative regulators perR, dtxR, and recG were activated more than 2.5-fold in pprM MT. These findings suggest that PprM is necessary for KatE1 production under normal culture conditions by down-regulation of katE1 negative regulators.

  5. PprA contributes to Deinococcus radiodurans resistance to nalidixic acid, genome maintenance after DNA damage and interacts with deinococcal topoisomerases.

    Science.gov (United States)

    Kota, Swathi; Charaka, Vijaya K; Ringgaard, Simon; Waldor, Matthew K; Misra, Hari S

    2014-01-01

    PprA is known to contribute to Deinococcus radiodurans' remarkable capacity to survive a variety of genotoxic assaults. The molecular bases for PprA's role(s) in the maintenance of the damaged D. radiodurans genome are incompletely understood, but PprA is thought to promote D. radiodurans's capacity for DSB repair. PprA is found in a multiprotein DNA processing complex along with an ATP type DNA ligase, and the D. radiodurans toposiomerase IB (DraTopoIB) as well as other proteins. Here, we show that PprA is a key contributor to D. radiodurans resistance to nalidixic acid (Nal), an inhibitor of topoisomerase II. Growth of wild type D. radiodurans and a pprA mutant were similar in the absence of exogenous genotoxic insults; however, the pprA mutant exhibited marked growth delay and a higher frequency of anucleate cells following treatment with DNA-damaging agents. We show that PprA interacts with both DraTopoIB and the Gyrase A subunit (DraGyrA) in vivo and that purified PprA enhances DraTopoIB catalysed relaxation of supercoiled DNA. Thus, besides promoting DNA repair, our findings suggest that PprA also contributes to preserving the integrity of the D. radiodurans genome following DNA damage by interacting with DNA topoisomerases and by facilitating the actions of DraTopoIB.

  6. Untargeted metabolite profiling reveals that nitric oxide bioynthesis is an endogenous modulator of carotenoid biosynthesis in Deinococcus radiodurans and is required for extreme ionizing radiation resistance.

    Science.gov (United States)

    Hansler, Alex; Chen, Qiuying; Ma, Yuliang; Gross, Steven S

    2016-01-01

    Deinococcus radiodurans (Drad) is the most radioresistant organism known. Although mechanisms that underlie the extreme radioresistance of Drad are incompletely defined, resistance to UV irradiation-induced killing was found to be greatly attenuated in an NO synthase (NOS) knockout strain of Drad (Δnos). We now show that endogenous NO production is also critical for protection of Drad against γ-irradiation (3000 Gy), a result of accelerated growth recovery, not protection against killing. NO-donor treatment rescued radiosensitization in Δnos Drad but did not influence radiosensitivity in wild type Drad. To discover molecular mechanisms by which endogenous NO confers radioresistance, metabolite profiling studies were performed. Untargeted LC-MS-based metabolite profiling in Drad quantified relative abundances of 1425 molecules and levels of 294 of these were altered by >5-fold (p < 0.01). Unexpectedly, these studies identified a dramatic perturbation in carotenoid biosynthetic intermediates in Δnos Drad, including a reciprocal switch in the pathway end-products from deoxydeinoxanthin to deinoxanthin. NO supplementation rescued these nos deletion-associated changes in carotenoid biosynthesis, and fully-restored radioresistance to wildtype levels. Because carotenoids were shown to be important contributors to radioprotection in Drad, our findings suggest that endogenously-produced NO serves to maintain a spectrum of carotenoids critical for Drad's ability to withstand radiation insult. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. In vitro affinity of Deinococcus radiodurans MutS towards mismatched DNA exceeds that of its orthologues from Escherichia coli and Thermus thermophilus.

    Science.gov (United States)

    Banasik, Michał; Stanisławska-Sachadyn, Anna; Hildebrandt, Ewa; Sachadyn, Paweł

    2017-06-20

    The mismatch binding protein MutS is responsible for the recognition of mispaired and unpaired bases, which is the initial step in DNA repair. Among the MutS proteins most extensively studied in vitro are those derived from Thermus thermophilus, Thermus aquaticus and Escherichia coli. Here, we present the first report on the in vitro examination of DNA mismatch binding activity of MutS protein from Deinococcus radiodurans and confront this with the properties of those from E. coli and T. thermophilus. The analyses which included mobility gel-shift assay, colorimetric and qPCR estimation of MutS-bound DNA clearly showed that D. radiodurans MutS exhibited much higher affinity towards mismatched DNA in vitro than its counterparts from E. coli and T. thermophilus. In addition, D. radiodurans MutS displayed a significantly higher specificity of DNA mismatch binding than the two other orthologues. The specificity expressed as the ratio of mismatched to fully complementary DNA bound reached over 4 and 20-fold higher values for D. radiodurans than for T. thermophilus and E. coli MutS, respectively. The results demonstrate mainly the biotechnological potential of D. radiodurans MutS but the in vitro characteristics of the MutS orthologues could reflect substantial differences in DNA mismatch binding activities existing in vivo. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The effects of pprI gene of Deinococcus radiodurans R1 on acute radiation injury of mice exposed to 60Co γ-ray radiation.

    Science.gov (United States)

    Chen, Ting-Ting; Hua, Wei; Zhang, Xi-Zhi; Wang, Bu-Hai; Yang, Zhan-Shan

    2017-01-10

    The role of the pprI gene from Deinococcus radiodurans R1 in therapy of acute radiation injury of a mammalian host was investigated. We injected a plasmid containing the pprI gene into the muscle of mice exposed to total 6Gy of 60Co γ-ray radiation. After injection, we used in vivo gene electroporation technology to transfer the pprI gene into the cell. We found the PprI protein was expressed significantly at 1 d after irradiation, but there was no expression of pprI gene 7 d post-irradiation. The expression of pprI gene evidently decreased the death rate of mice exposed to lethal dose radiation, significantly relieved effects on blood cells in the acute stage, shortened the persistence time of the decrease of lymphocytes, and decreased the apoptotic rates of spleen cells, thymocytes and bone marrow cells. The expression of Rad51 protein in the lungs, livers, and kidneys was significantly higher in the mice treated with the pprI plasmid after irradiation. However, there were no obvious differences for Rad52 protein expression. We conclude that the prokaryotic pprI gene of D. radiodurans R1 first was expressed in mammalian cells. The expressed prokaryotic PprI protein has distinct effects of the prevention and treatment on acute radiation injury of mammal. The effects of radio-resistance may relate to expression of Rad51 protein which is homologous with RecA from D. radiodurans.

  9. Regulation of MntH by a dual Mn(II- and Fe(II-dependent transcriptional repressor (DR2539 in Deinococcus radiodurans.

    Directory of Open Access Journals (Sweden)

    Hongxing Sun

    Full Text Available The high intracellular Mn/Fe ratio observed within the bacteria Deinococcus radiodurans may contribute to its remarkable resistance to environmental stresses. We isolated DR2539, a novel regulator of intracellular Mn/Fe homeostasis in D. radiodurans. Electrophoretic gel mobility shift assays (EMSAs revealed that DR2539 binds specifically to the promoter of the manganese acquisition transporter (MntH gene, and that DR0865, the only Fur homologue in D. radiodurans, cannot bind to the promoter of mntH, but it can bind to the promoter of another manganese acquisition transporter, MntABC. β-galactosidase expression analysis indicated that DR2539 acts as a manganese- and iron-dependent transcriptional repressor. Further sequence alignment analysis revealed that DR2539 has evolved some special characteristics. Site-directed mutagenesis suggested that His98 plays an important role in the activities of DR2539, and further protein-DNA binding activity assays showed that the activity of H98Y mutants decreased dramatically relative to wild type DR2539. Our study suggests that D. radiodurans has evolved a very efficient manganese regulation mechanism that involves its high intracellular Mn/Fe ratio and permits resistance to extreme conditions.

  10. Regulation of MntH by a Dual Mn(II)- and Fe(II)-Dependent Transcriptional Repressor (DR2539) in Deinococcus radiodurans

    Science.gov (United States)

    Xu, Guangzhi; Chen, Huan; Jiao, Jiandong; Tian, Bing; Wang, Liangyan; Hua, Yuejin

    2012-01-01

    The high intracellular Mn/Fe ratio observed within the bacteria Deinococcus radiodurans may contribute to its remarkable resistance to environmental stresses. We isolated DR2539, a novel regulator of intracellular Mn/Fe homeostasis in D. radiodurans. Electrophoretic gel mobility shift assays (EMSAs) revealed that DR2539 binds specifically to the promoter of the manganese acquisition transporter (MntH) gene, and that DR0865, the only Fur homologue in D. radiodurans, cannot bind to the promoter of mntH, but it can bind to the promoter of another manganese acquisition transporter, MntABC. β-galactosidase expression analysis indicated that DR2539 acts as a manganese- and iron-dependent transcriptional repressor. Further sequence alignment analysis revealed that DR2539 has evolved some special characteristics. Site-directed mutagenesis suggested that His98 plays an important role in the activities of DR2539, and further protein-DNA binding activity assays showed that the activity of H98Y mutants decreased dramatically relative to wild type DR2539. Our study suggests that D. radiodurans has evolved a very efficient manganese regulation mechanism that involves its high intracellular Mn/Fe ratio and permits resistance to extreme conditions. PMID:22523570

  11. PprA contributes to Deinococcus radiodurans resistance to nalidixic acid, genome maintenance after DNA damage and interacts with deinococcal topoisomerases.

    Directory of Open Access Journals (Sweden)

    Swathi Kota

    Full Text Available PprA is known to contribute to Deinococcus radiodurans' remarkable capacity to survive a variety of genotoxic assaults. The molecular bases for PprA's role(s in the maintenance of the damaged D. radiodurans genome are incompletely understood, but PprA is thought to promote D. radiodurans's capacity for DSB repair. PprA is found in a multiprotein DNA processing complex along with an ATP type DNA ligase, and the D. radiodurans toposiomerase IB (DraTopoIB as well as other proteins. Here, we show that PprA is a key contributor to D. radiodurans resistance to nalidixic acid (Nal, an inhibitor of topoisomerase II. Growth of wild type D. radiodurans and a pprA mutant were similar in the absence of exogenous genotoxic insults; however, the pprA mutant exhibited marked growth delay and a higher frequency of anucleate cells following treatment with DNA-damaging agents. We show that PprA interacts with both DraTopoIB and the Gyrase A subunit (DraGyrA in vivo and that purified PprA enhances DraTopoIB catalysed relaxation of supercoiled DNA. Thus, besides promoting DNA repair, our findings suggest that PprA also contributes to preserving the integrity of the D. radiodurans genome following DNA damage by interacting with DNA topoisomerases and by facilitating the actions of DraTopoIB.

  12. DR2539 is a novel DtxR-like regulator of Mn/Fe ion homeostasis and antioxidant enzyme in Deinococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Huan [Key Laboratory for Nuclear-Agricultural Sciences of Chinese Ministry of Agriculture and Zhejiang Province, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou 310029 (China); Zhejiang Institute of Microbiology, Zhejiang Province, Hangzhou 310012 (China); Wu, Rongrong [Department of Cardiology, Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310009 (China); Xu, Guangzhi [Key Laboratory for Nuclear-Agricultural Sciences of Chinese Ministry of Agriculture and Zhejiang Province, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou 310029 (China); Fang, Xu; Qiu, Xiaoli; Guo, Hongyin [Zhejiang Institute of Microbiology, Zhejiang Province, Hangzhou 310012 (China); Tian, Bing, E-mail: tianbing@zju.edu.cn [Key Laboratory for Nuclear-Agricultural Sciences of Chinese Ministry of Agriculture and Zhejiang Province, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou 310029 (China); Hua, Yuejin, E-mail: yjhua@zju.edu.cn [Key Laboratory for Nuclear-Agricultural Sciences of Chinese Ministry of Agriculture and Zhejiang Province, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou 310029 (China)

    2010-05-28

    Transcriptional regulators of the diphtheria toxin repressor (DtxR) family control the expression of genes involved in the uptake of iron and manganese, which is not only necessitous nutrients but also was suggested to be essential for intracellular redox cycling of microorganisms. We identified a unique DtxR homologue (DR2539) with special characteristics from Deinococcus radiodurans, which is known for its extreme resistance to radiation and oxidants. The dr2539 mutant showed higher resistance to hydrogen peroxide than the wild-type strain R1. Intracellular catalase activity assay and semiquantitative PCR analysis demonstrated that this DtxR is a negative regulator of catalase (katE). Furthermore, quantitative real-time PCR, global transcription profile and inductively coupled plasma-mass spectrometry analysis showed that the DtxR is involved in the regulation of antioxidant system by maintaining the intracellular Mn/Fe ion homeostasis of D. radiodurans. However, unlike the other DtxR homologues, the DtxR of D. radiodurans acts as a negative regulator of a Mn transporter gene (dr2283) and as a positive regulator of Fe-dependent transporter genes (dr1219, drb0125) in D. radiodurans.

  13. Genetic transformation of the bacterium Bacillus firmus for GFP expression and confocal laser microscopy analysis

    OpenAIRE

    Beltran Anadon, Daniel

    2017-01-01

    Bacillus firmus I-1582 is a bacterium with nematicidal effects on root-knot nematodes, a group of plant parasites pertaining to the genus Meloidogyne. This bacterium is able to colonize the plant rhizosphere of some economically important crops and protect them from nematode parasites by reducing their juvenile hatching, their only infective stage. In this final degree project B.firmus was transformed with a green fluorescent protein gene. To transform the bacterium it was necessary the previ...

  14. Complete genome sequence of the filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus

    National Research Council Canada - National Science Library

    Tang, Kuo-Hsiang; Barry, Kerrie; Chertkov, Olga; Dalin, Eileen; Han, Cliff S; Hauser, Loren J; Honchak, Barbara M; Karbach, Lauren E; Land, Miriam L; Lapidus, Alla; Larimer, Frank W; Mikhailova, Natalia; Pitluck, Samuel; Pierson, Beverly K; Blankenship, Robert E

    2011-01-01

    Chloroflexus aurantiacus is a thermophilic filamentous anoxygenic phototrophic (FAP) bacterium, and can grow phototrophically under anaerobic conditions or chemotrophically under aerobic and dark conditions...

  15. Molybdate Reduction to Molybdenum Blue by an Antarctic Bacterium

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    S. A. Ahmad

    2013-01-01

    Full Text Available A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo6+ to molybdenum blue (Mo-blue. Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries.

  16. Biological Control of Meloidogyne hapla Using an Antagonistic Bacterium

    Directory of Open Access Journals (Sweden)

    Jiyeong Park

    2014-09-01

    Full Text Available We examined the efficacy of a bacterium for biocontrol of the root-knot nematode (RKN Meloidogyne hapla in carrot (Daucus carota subsp. sativus and tomato (Solanum lycopersicum. Among 542 bacterial isolates from various soils and plants, the highest nematode mortality was observed for treatments with isolate C1-7, which was identified as Bacillus cereus based on cultural and morphological characteristics, the Biolog program, and 16S rRNA sequencing analyses. The population density and the nematicidal activity of B. cereus C1-7 remained high until the end of culture in brain heart infusion broth, suggesting that it may have sustainable biocontrol potential. In pot experiments, the biocontrol efficacy of B. cereus C1-7 was high, showing complete inhibition of root gall or egg mass formation by RKN in carrot and tomato plants, and subsequently reducing RKN damage and suppressing nematode population growth, respectively. Light microscopy of RKN-infected carrot root tissues treated with C1-7 showed reduced formation of gall cells and fully developed giant cells, while extensive gall cells and fully mature giant cells with prominent cell wall ingrowths formed in the untreated control plants infected with RKNs. These histopathological characteristics may be the result of residual or systemic biocontrol activity of the bacterium, which may coincide with the biocontrol efficacies of nematodes in pots. These results suggest that B. cereus C1-7 can be used as a biocontrol agent for M. hapla.

  17. Pathogenesis of helicobacter pylori infection: Bacterium and host relationship

    Directory of Open Access Journals (Sweden)

    Sokić-Milutinović Aleksandra

    2004-01-01

    Full Text Available Helicobacter pylori (H. pylori colonizes the gastric mucosa of a half of the mankind. Duodenal ulcer is found in 15-25%, t gastric ulcer in 13%, while gastric adenocarcinoma develops in 1% of all infected individuals. Pathogenesis of H. pylori infection is related to the virulence factors of the bacterium, environmental (dietary habits, hygiene, stress and host factors (age, sex, blood type. Colonization of the gastric mucosa is related to the motility of the bacterium, presence of lipopolysacharide (LPS and various bacterial enzymes. Gastric mucosal injury is the result of H. pylori LPS, vacuolization cytotoxin (vacA, cytotoxin associated protein (cagA, heat shock proteins and factors responsible for neutrophil chemotaxis and activity. H. pylori colonizes the gastric mucosa and zones of ectopic gastric epithelium. H. pylori infection is transmitted via oral-oral, fecal-oral and iatrogenic way (during endoscopy. Higher prevalence of the infection is associated with lower socioeconomic level, lack of drinking water, and living in a community. Acute H. pylori gastritis is superficial pangastritis progressing into the chronic phase after 7-10 days. Gastric mucosal atrophy and intestinal metaplasia can develop during the course of H. pylori infection. Clearly defined factors that influence the outcome of H. pylori infection include bacterial strain, distribution of gastritis, acid secretion and gastric mucosal atrophy.

  18. Novel Trypanosomatid-Bacterium Association: Evolution of Endosymbiosis in Action.

    Science.gov (United States)

    Kostygov, Alexei Y; Dobáková, Eva; Grybchuk-Ieremenko, Anastasiia; Váhala, Dalibor; Maslov, Dmitri A; Votýpka, Jan; Lukeš, Julius; Yurchenko, Vyacheslav

    2016-03-15

    We describe a novel symbiotic association between a kinetoplastid protist, Novymonas esmeraldas gen. nov., sp. nov., and an intracytoplasmic bacterium, "Candidatus Pandoraea novymonadis" sp. nov., discovered as a result of a broad-scale survey of insect trypanosomatid biodiversity in Ecuador. We characterize this association by describing the morphology of both organisms, as well as their interactions, and by establishing their phylogenetic affinities. Importantly, neither partner is closely related to other known organisms previously implicated in eukaryote-bacterial symbiosis. This symbiotic association seems to be relatively recent, as the host does not exert a stringent control over the number of bacteria harbored in its cytoplasm. We argue that this unique relationship may represent a suitable model for studying the initial stages of establishment of endosymbiosis between a single-cellular eukaryote and a prokaryote. Based on phylogenetic analyses, Novymonas could be considered a proxy for the insect-only ancestor of the dixenous genus Leishmania and shed light on the origin of the two-host life cycle within the subfamily Leishmaniinae. The parasitic trypanosomatid protist Novymonas esmeraldas gen. nov., sp. nov. entered into endosymbiosis with the bacterium "Ca. Pandoraea novymonadis" sp. nov. This novel and rather unstable interaction shows several signs of relatively recent establishment, qualifying it as a potentially unique transient stage in the increasingly complex range of eukaryotic-prokaryotic relationships. Copyright © 2016 Kostygov et al.

  19. Viruses in the desert: a metagenomic survey of viral communities in four perennial ponds of the Mauritanian Sahara.

    Science.gov (United States)

    Fancello, Laura; Trape, Sébatien; Robert, Catherine; Boyer, Mickaël; Popgeorgiev, Nikolay; Raoult, Didier; Desnues, Christelle

    2013-02-01

    Here, we present the first metagenomic study of viral communities from four perennial ponds (gueltas) located in the central Sahara (Mauritania). Three of the four gueltas (Ilij, Molomhar and Hamdoun) are located at the source of three different wadis belonging to the same hydrologic basin, whereas the fourth (El Berbera) belongs to a different basin. Overall, sequences belonging to tailed bacteriophages were the most abundant in all four metagenomes although electron microscopy and sequencing confirmed the presence of other viral groups, such as large DNA viruses. We observed a decrease in the local viral biodiversity in El Berbera, a guelta with sustained human activities, compared with the pristine Ilij and Molomhar, and sequences related to viruses infecting crop pests were also detected as a probable consequence of the agricultural use of the soil. However, the structure of the El Berbera viral community shared the common global characteristics of the pristine gueltas, that is, it was dominated by Myoviridae and, more particularly, by virulent phages infecting photosynthetic cyanobacteria, such as Prochlorococcus and Synechococcus spp. In contrast, the Hamdoun viral community was characterized by a larger proportion of phages with the potential for a temperate lifestyle and by dominant species related to phages infecting heterotrophic bacteria commonly found in terrestrial environments. We hypothesized that the differences observed in the structural and functional composition of the Hamdoun viral community resulted from the critically low water level experienced by the guelta.

  20. Holocene freshwater carbonate structures in the hyper-arid Gebel Uweinat region of the Sahara Desert (Southwestern Egypt)

    Science.gov (United States)

    Marinova, Margarita M.; Meckler, A. Nele; McKay, Christopher P.

    2014-01-01

    The eastern part of the Sahara is at present the driest region of the desert. Yet the extensive animal rock art in the area, presumed to depict real activities in the lives of the painters, suggests that environmental conditions were significantly different when the rock art was produced. Here we report on exploration of the area, which led to the discovery of morphologically-distinct carbonate structures that line the walls of two valleys in Gebel Uweinat, and were likely formed in standing water. The carbonate structures comprise what appear to be shoreline carbonate formations, and date back to 8100 and 9400 years BP. The chemical and morphological similarity of these formations to carbonate structures from modern lakes suggests that these lakes contained fresh, standing water suitable for human and animal use. However, the significant quartz content suggests that windblown sand was pervasive, and thus the vegetation cover may have been sparse. This discovery supports the possibility of grasslands in the area, which may have been able to support human habitation, and adds to the evidence for a wetter climate in the area in the early Holocene.