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Sample records for antarctic arthrobacter sp

  1. Xylanolytic enzyme systems in Arthrobacter sp MTCC 5214 and Lactobacillus sp.

    Digital Repository Service at National Institute of Oceanography (India)

    Khandeparker, R.; Jalal, T.

    The production of extracellular xylanolytic enzymes such as xylanase, alfa-L-arabinofuranosidase (alfa-l-AFase), and acetyl xylan esterase (Axe) by marine Arthrobacter sp and Lactobacillus sp was investigated using different carbon sources Induction...

  2. Arthrobacter ruber sp. nov., isolated from glacier ice.

    Science.gov (United States)

    Liu, Qing; Xin, Yu-Hua; Chen, Xiu-Ling; Liu, Hong-Can; Zhou, Yu-Guang; Chen, Wen-Xin

    2018-03-21

    A Gram-stain-positive strain designated MDB1-42 T was isolated from ice collected from Midui glacier in Tibet, PR China. Strain MDB1-42 T was catalase-positive, oxidase-negative and grew optimally at 25-28 °C and pH 7.0. Phylogenetic analysis based on 16S rRNA gene sequences revealed that MDB1-42 T represented a member of the genus Arthrobacter. The highest level of 16S rRNA gene sequence similarity (99.86 %) was found with Arthrobacter agilis NBRC 15319 T . Multilocus sequence analysis revealed low similarity of 91.93 % between MDB1-42 T and Arthrobacter agilis NBRC 15319 T . Average nucleotide identity and digital DNA-DNA hybridization values between MDB1-42 T and the most closely related strain, Arthrobacter agilis DSM 20550 T , were 81.36 and 24.5 %, respectively. The genomic DNA G+C content was 69.0 mol%. The major cellular fatty acids of MDB1-42 T were anteiso-C15 : 0 and anteiso-C17:0. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, one unidentified glycolipid and one unidentified lipid. The predominant menaquinone was MK-9(H2). On the basis of results obtained using a polyphasic approach, a novel species Arthrobacter ruber sp. nov. is proposed, with MDB1-42 T (=CGMCC 1.9772 T =NBRC 113088 T ) as the type strain.

  3. Produksi, isolasi dan karakterisasi enzim dekstranase dari Arthrobacter sp. B7

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    Afaf Baktir

    2012-02-01

    Full Text Available Dextranase enzyme has been purified and characterized from Arthrobacter sp. B7. This enzyme was purified from the culture supernatant of Arthrobacter sp. B7 by procedure of native PAGE. The molecular size of the enzyme was estimated 72,5 kDa by SDSPAGE. The N-terminal amino acid sequence of this enzyme determined using Edman degradation techniques were APVTADVGNLHT. SDS-PAGE and native-PAGE analysis revealed that the enzyme molecule consisted of one sub-unit.

  4. Potential Degradation of Swainsonine by Intracellular Enzymes of Arthrobacter sp. HW08

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    Haili Li

    2013-11-01

    Full Text Available Swainsonine (SW is a toxin produced by locoweeds and harmful to the livestock industry. Degrading SW by Arthrobacter sp. HW08 was demonstrated as a promising way to deal with SW poisoning. However, it is unknown which part of the subcellular enzymes in Arthrobacter sp. HW08 is responsible for biodegrading SW and whether the metabolites are atoxic. In this study, intracellular and extracellular enzymes of Arthrobacter sp. HW08 were isolated and their enzyme activity was evaluated. The metabolites were fed to mice, and physiological and histological properties of the treated mice were investigated. The results showed that only intracellular enzyme of Arthrobacter sp. HW08 (IEHW08 could degrade SW efficiently. Compared with mice in SW treatment group, mice in SW + IEHW08 treatment group (1 increased their body weights; (2 showed higher number of platelets and lower number of white blood cells; (3 decreased the levels of creatinine, urea nitrogen, alanine transaminase and aspartate aminotransferase in serum; (4 reduced the number of vacuolated cells in cerebellum, liver and kidney. All these data demonstrate that IEHW08 was potentially safe for mice, while keeping the capacity of degrading SW. This study indicates a possible application of IEHW08 as an additive in the livestock industry to protect animals from SW poisoning.

  5. Purification and Characterization of Haloalcohol Dehalogenase from Arthrobacter sp. Strain AD2

    NARCIS (Netherlands)

    van den Wijngaard, Arjen J.; Reuvekamp, Peter T.W.; Janssen, Dick B.

    An enzyme capable of dehalogenating vicinal haloalcohols to their corresponding epoxides was purified from the 3-chloro-1,2-propanediol-utilizing bacterium Arthrobacter sp. strain AD2. The inducible haloalcohol dehalogenase converted 1,3-dichloro-2-propanol, 3-chloro-1,2-propanediol,

  6. A method for the production of D-tagatose using a recombinant Pichia pastoris strain secreting β-D-galactosidase from Arthrobacter chlorophenolicus and a recombinant L-arabinose isomerase from Arthrobacter sp. 22c.

    Science.gov (United States)

    Wanarska, Marta; Kur, Józef

    2012-08-23

    D-Tagatose is a natural monosaccharide which can be used as a low-calorie sugar substitute in food, beverages and pharmaceutical products. It is also currently being tested as an anti-diabetic and obesity control drug. D-Tagatose is a rare sugar, but it can be manufactured by the chemical or enzymatic isomerization of D-galactose obtained by a β-D-galactosidase-catalyzed hydrolysis of milk sugar lactose and the separation of D-glucose and D-galactose. L-Arabinose isomerases catalyze in vitro the conversion of D-galactose to D-tagatose and are the most promising enzymes for the large-scale production of D-tagatose. In this study, the araA gene from psychrotolerant Antarctic bacterium Arthrobacter sp. 22c was isolated, cloned and expressed in Escherichia coli. The active form of recombinant Arthrobacter sp. 22c L-arabinose isomerase consists of six subunits with a combined molecular weight of approximately 335 kDa. The maximum activity of this enzyme towards D-galactose was determined as occurring at 52°C; however, it exhibited over 60% of maximum activity at 30°C. The recombinant Arthrobacter sp. 22c L-arabinose isomerase was optimally active at a broad pH range of 5 to 9. This enzyme is not dependent on divalent metal ions, since it was only marginally activated by Mg2+, Mn2+ or Ca2+ and slightly inhibited by Co2+ or Ni2+. The bioconversion yield of D-galactose to D-tagatose by the purified L-arabinose isomerase reached 30% after 36 h at 50°C. In this study, a recombinant Pichia pastoris yeast strain secreting β-D-galactosidase Arthrobacter chlorophenolicus was also constructed. During cultivation of this strain in a whey permeate, lactose was hydrolyzed and D-glucose was metabolized, whereas D-galactose was accumulated in the medium. Moreover, cultivation of the P. pastoris strain secreting β-D-galactosidase in a whey permeate supplemented with Arthrobacter sp. 22c L-arabinose isomerase resulted in a 90% yield of lactose hydrolysis, the complete utilization

  7. A method for the production of D-tagatose using a recombinant Pichia pastoris strain secreting β-D-galactosidase from Arthrobacter chlorophenolicus and a recombinant L-arabinose isomerase from Arthrobacter sp. 22c

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    Wanarska Marta

    2012-08-01

    Full Text Available Abstract Background D-Tagatose is a natural monosaccharide which can be used as a low-calorie sugar substitute in food, beverages and pharmaceutical products. It is also currently being tested as an anti-diabetic and obesity control drug. D-Tagatose is a rare sugar, but it can be manufactured by the chemical or enzymatic isomerization of D-galactose obtained by a β-D-galactosidase-catalyzed hydrolysis of milk sugar lactose and the separation of D-glucose and D-galactose. L-Arabinose isomerases catalyze in vitro the conversion of D-galactose to D-tagatose and are the most promising enzymes for the large-scale production of D-tagatose. Results In this study, the araA gene from psychrotolerant Antarctic bacterium Arthrobacter sp. 22c was isolated, cloned and expressed in Escherichia coli. The active form of recombinant Arthrobacter sp. 22c L-arabinose isomerase consists of six subunits with a combined molecular weight of approximately 335 kDa. The maximum activity of this enzyme towards D-galactose was determined as occurring at 52°C; however, it exhibited over 60% of maximum activity at 30°C. The recombinant Arthrobacter sp. 22c L-arabinose isomerase was optimally active at a broad pH range of 5 to 9. This enzyme is not dependent on divalent metal ions, since it was only marginally activated by Mg2+, Mn2+ or Ca2+ and slightly inhibited by Co2+ or Ni2+. The bioconversion yield of D-galactose to D-tagatose by the purified L-arabinose isomerase reached 30% after 36 h at 50°C. In this study, a recombinant Pichia pastoris yeast strain secreting β-D-galactosidase Arthrobacter chlorophenolicus was also constructed. During cultivation of this strain in a whey permeate, lactose was hydrolyzed and D-glucose was metabolized, whereas D-galactose was accumulated in the medium. Moreover, cultivation of the P. pastoris strain secreting β-D-galactosidase in a whey permeate supplemented with Arthrobacter sp. 22c L-arabinose isomerase resulted in a 90% yield

  8. Purification and characterization of alpha-L-arabinofuranosidase from Arthrobacter sp. MTCC 5214 in solid-state fermentation

    Digital Repository Service at National Institute of Oceanography (India)

    Khandeparker, R.; Numan, M.T.H.; Mukherjee, B.; Satwekar, A.; Bhosle, N.B.

    Arthrobacter sp. MTCC 5214 produced an a-L-arabinofuranosidase when grown on solid-state fermentation (SSF). The enzyme was purified 19-fold using ion exchange and gel filtration chromatography. The enzyme had an apparent molecular mass of approx...

  9. [Screening, identification and characterization of a quinclorac-degrading Arthrobacter sp. MC-10].

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    Zhang, Shun; Huang, Guolian; Xu, Jialai; Li, Bin; Li, Hongguang; Chen, Dexin

    2015-01-04

    We screened and isolated bacterial strains from the perennial administration quinclorac paddy fields to degrade quinclorac. Strain MC-10, which can degrade quinclorac efficiently, was screened by enrichment and selective medium. The strain was identified by morphological, physio-biochemical characteristics and 16S rDNA gene sequence analysis. MC-10 was identified as Arthrobacter sp. Under the optimal growth conditions with inoculum concentration of 5%, at 28 °C, pH 7 for 7 d, MC-10 degraded more than 90% of quinclorac. MC-10 can effectively degrade quinclorac when quinclorac initial concentration at 1 mg/L--100 mg/L. And the strain MC-10 has a good ability to survive in the soil. More than 70% quinclorac in the soil can be degraded efficiently after 7 days of cultivation. Arthrobacter sp. MC-10 could be a promising microorganism in dealing with quinclorac pollution.

  10. The Potency of Dextranase from Arthrobacter sp. Strain B7 as Dental Plaque Removal

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    AFAF BAKTIR

    2005-12-01

    Full Text Available Dextranase of Arthrobacter sp. strain B7 (B7DEX enzyme was characterized in this study. This enzyme hydrolyzed sucrose and dextran, but not other glucans (starch, nigeran, cellulose, -soluble glucan. It also hydrolyzed glucan from dental plaque with the activity of 7.38 + 0.66 U/ml, where the activity toward dextran was 31.88 + 1.24 U/ml. The enzyme exhibited the pH optimum of 7 and the temperature optimum of 50 oC. Its optimum stability was at pH 7 and 50 oC. The enzyme was inhibited by Fe3+, Cu2+, Zn2+, and Ag+, but not by the anionic detergent (SDS and the nonionic detergent (Triton-X. The enzyme was activated by Ca2+, Na+, Mg2+, and saliva.

  11. Potensi Enzim Dekstranase dari Arthrobacter sp. Galur B7 sebagai Penghambat Plak Gigi

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    AFAF BAKTIR

    2005-12-01

    Full Text Available Dextranase of Arthrobacter sp. strain B7 (B7DEX enzyme was characterized in this study. This enzyme hydrolyzed sucrose and dextran, but not other glucans (starch, nigeran, cellulose, β-soluble glucan. It also hydrolyzed glucan from dental plaque with the activity of 7.38 ± 0.66 U/ml, where the activity toward dextran was 31.88 ± 1.24 U/ml. The enzyme exhibited the pH optimum of 7 and the temperature optimum of 50 °C. Its optimum stability was at pH 7 and 50 °C. The enzyme was inhibited by Fe3+, Cu2+, Zn2+, and Ag+, but not by the anionic detergent (SDS and the nonionic detergent (Triton-X. The enzyme was activated by Ca2+, Na+, Mg2+, and saliva.

  12. Arthrobacter pokkalii sp nov, a Novel Plant Associated Actinobacterium with Plant Beneficial Properties, Isolated from Saline Tolerant Pokkali Rice, Kerala, India.

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    Ramya Krishnan

    support the classification of strain P3B162T as a novel Arthrobacter species and we propose Arthrobacter pokkalii sp.nov.as its name. The type strain is P3B162T (= KCTC 29498T = MTCC 12358T.

  13. Arthrobacter nitroguajacolicus sp. nov., a novel 4-nitroguaiacol-degrading actinobacterium

    Czech Academy of Sciences Publication Activity Database

    Koutoučková, L.; Schumann, P.; Durnová, E.; Spröer, C.; Sedláček, I.; Neča, J.; Zdráhal, Zbyněk; Němec, M.

    2004-01-01

    Roč. 54, č. 3 (2004), s. 773-777 ISSN 1466-5026 R&D Projects: GA ČR GA204/00/P095 Institutional research plan: CEZ:AV0Z4031919 Keywords : Nitroguaiacol * actinobacterium * Arthrobacter Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.015, year: 2004

  14. A new lipopeptide biosurfactant produced by Arthrobacter sp. strain MIS38.

    OpenAIRE

    Morikawa, M; Daido, H; Takao, T; Murata, S; Shimonishi, Y; Imanaka, T

    1993-01-01

    A biosurfactant termed arthrofactin produced by Arthrobacter species strain MIS38 was purified and chemically characterized as 3-hydroxydecanoyl-D-leucyl-D-asparagyl-D-threonyl-D- leucyl-D-leucyl-D-seryl-L-leucyl-D-seryl-L-isoleucyl-L-isoleucyl-L-as paragyl lactone. Surface activity of arthrofactin was examined, with surfactin as a control. Critical micelle concentration values of arthrofactin and surfactin were around 1.0 x 10(-5) M and 7.0 x 10(-5) M at 25 degrees C, respectively. Arthrofac...

  15. Mucilaginibacter terrae sp nov., isolated from Antarctic soil

    Czech Academy of Sciences Publication Activity Database

    Sedláček, I.; Pantůček, R.; Králová, S.; Mašlaňová, I.; Holochová, P.; Staňková, E.; Sobotka, Roman; Barták, M.; Busse, H.-J.; Švec, P.

    2017-01-01

    Roč. 67, č. 10 (2017), s. 4002-4007 ISSN 1466-5026 R&D Projects: GA MŠk(CZ) LO1416 Institutional support: RVO:61388971 Keywords : Mucilaginibacter terrae sp nov. * James ross island * Antarctic Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 2.134, year: 2016

  16. Ethanol production from inulin and unsterilized meal of Jerusalem artichoke tubers by Saccharomyces sp. W0 expressing the endo-inulinase gene from Arthrobacter sp.

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    Li, Yang; Liu, Guang-Lei; Chi, Zhen-Ming

    2013-11-01

    After the endo-inulinase gene from Arthrobacter sp. was ligated the expression vectors pMIDSC31 and pMIRSC31, the endo-inulinase gene was inserted into the chromosomal DNA of Saccharomyces sp. W0. It was found that the inulinase activity of the recombinant yeast D5 in which the endo-inulinase gene was inserted into the delta sequence was higher than that of the recombinant yeast R1 in which the endo-inulinase gene was inserted into 18S rDNA sequence. More ethanol from inulin was produced by the recombinant yeast D5 than by the recombinant yeast R1. But Saccharomyces sp. W0 produced the lowest inulinase activity and concentration of ethanol. During the 3-l fermentation, the recombinant yeast D5 could produce 13.6 ml of ethanol per 100ml of the fermented medium from 30% inulin. The recombinant yeast D5 could actively convert the unsterilized meal of Jerusalem artichoke tubers, yielding 10.1 ml of ethanol per 100ml of the fermented medium. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. First record of Babesia sp. in Antarctic penguins.

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    Montero, Estrella; González, Luis Miguel; Chaparro, Alberto; Benzal, Jesús; Bertellotti, Marcelo; Masero, José A; Colominas-Ciuró, Roger; Vidal, Virginia; Barbosa, Andrés

    2016-04-01

    This is the first reported case of Babesia sp. in Antarctic penguins, specifically a population of Chinstrap penguins (Pygoscelis antarctica) in the Vapour Col penguin rookery in Deception Island, South Shetlands, Antarctica. We collected peripheral blood from 50 adult and 30 chick Chinstrap penguins. Examination of the samples by microscopy showed intraerythrocytic forms morphologically similar to other avian Babesia species in 12 Chinstrap penguin adults and seven chicks. The estimated parasitaemias ranged from 0.25×10(-2)% to 0.75×10(-2)%. Despite the low number of parasites found in blood smears, semi-nested PCR assays yielded a 274 bp fragment in 12 of the 19 positive blood samples found by microscopy. Sequencing revealed that the fragment was 97% similar to Babesia sp. 18S rRNA from Australian Little Penguins (Eudyptula minor) confirming presence of the parasite. Parasite prevalence estimated by microscopy in adults and chicks was higher (24% vs. 23.3%, respectively) than found by semi-nested PCR (16% vs. 13.3% respectively). Although sampled penguins were apparently healthy, the effect of Babesia infection in these penguins is unknown. The identification of Babesia sp. in Antarctic penguins is an important finding. Ixodes uriae, as the only tick species present in the Antarctic Peninsula, is the key to understanding the natural history of this parasite. Future work should address the transmission dynamics and pathogenicity of Babesia sp. in Chinstrap penguin as well as in other penguin species, such as Gentoo penguin (Pygoscelis papua) and Adélie penguin (Pygoscelis adeliae), present within the tick distribution range in the Antarctic Peninsula. Copyright © 2016 Elsevier GmbH. All rights reserved.

  18. Identification of a recombinant inulin fructotransferase (difructose dianhydride III forming) from Arthrobacter sp. 161MFSha2.1 with high specific activity and remarkable thermostability.

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    Wang, Xiao; Yu, Shuhuai; Zhang, Tao; Jiang, Bo; Mu, Wanmeng

    2015-04-08

    Difructose dianhydride III (DFA III) is a functional carbohydrate produced from inulin by inulin fructotransferase (IFTase, EC 4.2.2.18). In this work, an IFTase gene from Arthrobacter sp. 161MFSha2.1 was cloned and expressed in Escherachia coli. The recombinant enzyme was purified by metal affinity chromatography. It showed significant inulin hydrolysis activity, and the produced main product from inulin was determined as DFA III by nuclear magnetic resonance analysis. The molecular mass of the purified protein was calculated to be 43 and 125 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration, respectively, suggesting the native enzyme might be a homotrimer. The recombinant enzyme showed maximal activity as 2391 units/mg at pH 6.5 and 55 °C. It displayed the highest thermostability among previously reported IFTases (DFA III forming) and was stable up to 80 °C for 4 h of incubation. The smallest substrate was determined as nystose. The conversion ratio of inulin to DFA III reached 81% when 100 g/L inulin was catalyzed by 80 nM recombinant enzyme for 20 min at pH 6.5 and 55 °C. All of these data indicated that the IFTase (DFA III forming) from Arthrobacter sp. 161MFSha2.1 had great potential for industrial DFA III production.

  19. Complete detoxification of tris(1,3-dichloro-2-propyl) phosphate by mixed two bacteria, Sphingobium sp. strain TCM1 and Arthrobacter sp. strain PY1.

    Science.gov (United States)

    Takahashi, Shouji; Obana, Yuki; Okada, Shohei; Abe, Katsumasa; Kera, Yoshio

    2012-01-01

    Tris(1,3-dichloro-2-propyl) phosphate (TDCPP), a flame retardant, is regarded as a potentially toxic and persistent environmental contaminant. We previously isolated a TDCPP-degrading bacterium, Sphingobium sp. strain TCM1, which, however, produced a toxic metabolite: 1,3-dichloro-2-propanol (1,3-DCP). This study was undertaken to develop a technique for complete TDCPP detoxification using strain TCM1 with a 1,3-DCP-degrading bacterium, Arthrobacter sp. strain PY1. For efficient detoxification, we designed a resting cell system and examined the effect of freezing and lyophilization treatments for preparation of their resting cells. Results show that treatments had no marked adverse effect on their activities. The TDCPP dephosphorylation by TCM1 resting cells was optimal at 30°C and pH 8.5. Also, 1,3-DCP dehalogenation by strain PY1 resting cells was optimal at 35°C and pH 9.5. Under those respective conditions, the activities were 2.48 μmol h⁻¹·OD₆₆₀⁻¹ for TDCPP and 0.95 μmol h⁻¹·OD₆₆₀⁻¹ for 1,3-DCP. Based on these results, we set the reaction temperature to 30°C and pH to 9.0. Then we examined the detoxification of 50 μM TDCPP using mixed resting cells at a final OD(660) of 0.05 for strain TCM1 and 0.2 for strain PY1. In these conditions, TDCPP was eliminated after 1h, but some of the resulting 1,3-DCP remained at a constant level. The increase in strain PY1 cells to a final OD₆₆₀ of 4.0 decreased the TDCPP dephosphorylation rate of strain TCM1 cells but achieved complete detoxification of TDCPP during 12 h of reaction. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  20. Rapid Biosynthesis of Silver Nanoparticles Based on Flocculation and Reduction of an Exopolysaccharide from Arthrobacter sp. B4: Its Antimicrobial Activity and Phytotoxicity

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    Li Yumei

    2017-01-01

    Full Text Available Silver nanoparticles (AgNPs were rapidly synthesized using an exopolysaccharide from Arthrobacter sp. B4 (B4-EPS. The optimum condition for AgNPs synthesis was under the concentration of 5 g/L B4-EPS and 1 mM AgNO3 at 80°C between pH 7.0 and 8.0. The resulting AgNPs displayed a face-centred-cubic structure with the size range from 9 nm to 72 nm. Further analysis showed that flocculation and reduction of B4-EPS played a pivotal role in the formation of AgNPs. Furthermore, these nanoparticles exhibited great stability, excellent antimicrobial activity, and low phytotoxicity. The aforementioned data provide a feasible and efficient approach for green synthesis of AgNPs using microbial polysaccharides with flocculation and reduction activity, which will be promising in medical filed.

  1. Crystallization and X-ray diffraction analysis of nylon hydrolase (NylC) from Arthrobacter sp. KI72.

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    Nagai, Keisuke; Yasuhira, Kengo; Tanaka, Yusuke; Kato, Dai-ichiro; Takeo, Masahiro; Higuchi, Yoshiki; Negoro, Seiji; Shibata, Naoki

    2013-10-01

    Nylon hydrolase (NylC) encoded by Arthrobacter plasmid pOAD2 (NylCp2) was expressed in Escherichia coli JM109 and purified by ammonium sulfate fractionation, anion-exchange column chromatography and gel-filtration chromatography. NylCp2 was crystallized by the sitting-drop vapour-diffusion method with ammonium sulfate as a precipitant in 0.1 M HEPES buffer pH 7.5 containing 0.2 M NaCl and 25% glycerol. Diffraction data were collected from the native crystal to a resolution of 1.60 Å. The obtained crystal was spindle shaped and belonged to the C-centred orthorhombic space group C2221, with unit-cell parameters a=70.84, b=144.90, c=129.05 Å. A rotation and translation search gave one clear solution containing two molecules per asymmetric unit.

  2. Pseudomonas versuta sp. nov., isolated from Antarctic soil.

    Science.gov (United States)

    See-Too, Wah Seng; Salazar, Sergio; Ee, Robson; Convey, Peter; Chan, Kok-Gan; Peix, Álvaro

    2017-06-01

    In this study we analysed three bacterial strains coded L10.10 T , A4R1.5 and A4R1.12, isolated in the course of a study of quorum-quenching bacteria occurring in Antarctic soil. The 16S rRNA gene sequence was identical in the three strains and showed 99.7% pairwise similarity with respect to the closest related species Pseudomonas weihenstephanensis WS4993 T . Therefore, the three strains were classified within the genus Pseudomonas. Analysis of housekeeping genes (rpoB, rpoD and gyrB) sequences showed similarities of 84-95% with respect to the closest related species of Pseudomonas, confirming its phylogenetic affiliation. The ANI values were less than 86% to the closest related species type strains. The respiratory quinone is Q9. The major fatty acids are C16:0, C16:1 ω7c/ C16:1 ω6c in summed feature 3 and C18:1 ω7c / C18:1 ω6c in summed feature 8. The strains are oxidase- and catalase-positive. Growth occurs at 4-30°C, and at pH 4.0-10. The DNA G+C content is 58.2-58.3mol %. The combined genotypic, phenotypic and chemotaxonomic data support the classification of strains L10.10 T , A4R1.5 and A4R1.12 into a novel species of Pseudomonas, for which the name P. versuta sp. nov. is proposed. The type strain is L10.10 T (LMG 29628 T , DSM 101070 T ). Copyright © 2017 Elsevier GmbH. All rights reserved.

  3. Hymenobacter rubripertinctus sp. nov., isolated from Antarctic tundra soil.

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    Jiang, Fan; Danzeng, Wangmu; Zhang, Yuming; Zhang, Yan; Jiang, Li; Liu, Jia; Lu, Lu; Fan, Wei; Peng, Fang

    2018-02-01

    A red-pigmented, Gram-reaction-negative, aerobic, non-motile and rod-shaped bacterium, designated NY03-3-30 T , was isolated from a soil sample collected from Inexpressible Island, Northern Victoria Land of the Antarctic Ross Orogen, and subjected to a polyphasic taxonomic study. Growth occurred at 4-28 °C (optimum 20 °C) and at pH 6.0-9.0 (optimum pH 7.0). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NY03-3-30 T belonged to the genus Hymenobacter in the family Cytophagaceae. 16S rRNA gene sequence similarities between strain NY03-3-30 T and the type strains of Hymenobacter species with validly published names ranged from 92.7 to 96.2 %. Strain NY03-3-30 T contained summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0, C16 : 0, C16 : 1ω5c, anteiso-C15 : 0 and summed feature 4 (iso-C17 : 1-I and/or anteiso-C17 : 1-B) as major cellular fatty acids, MK-7 as the respiratory quinone and phosphatidylethanolamine as the main polar lipid. The DNA G+C content of strain NY03-3-30 T was 59.4 mol%. On the basis of phylogenetic, physiological and chemotaxonomic data, strain NY03-3-30 T is considered to represent a novel species of genus Hymenobacter, for which the name Hymenobacter rubripertinctus sp. nov. is proposed. The type strain is NY03-3-30 T (=CCTCC AB 2017095 T =KCTC 62163 T ).

  4. Similarities in the induction of synthesis of a cell-surface polypeptide in Arthrobacter sp. by near-UV irradiation and photodynamic conditions

    International Nuclear Information System (INIS)

    Hoober, J.K.; Franzi, J.

    1983-01-01

    Irradiation of aerobic suspensions of Arthrobacter sp. with near-UV light (310-400 nm) induced synthesis of a 21 000 dalton, cell-surface polypeptide. Synthesis of this polypeptide also was induced by visible light in the presence of photodynamic dyes. Induction of the polypeptide in ear-UV light and with visible light plus dyes was inhibited by histidine. Hemin inhibited induction in near-UV light and in visible light with methylene blue, neutral red and acriflavin, which are cationic dyes, but failed to inhibit induction in visible light with rose bengal, an anionic dye. These results suggested that inhibition by hemin required electrostatically favored interaction between the anionic porphyrin and the sensitizer, and that the near-UV light effect was mediated by a cationic or neutral endogenous sensitizer. The similarities in the responses of the cells to near-UV irradiation and visible light plus dyes suggested that the mechanism of induction under the two conditions was the same. (author)

  5. Induction of a M/sub r/ 21,000 polypeptide in an Arthrobacter Sp. by dye-sensitized photooxidation

    International Nuclear Information System (INIS)

    Franzi, J.J.

    1985-01-01

    Irradiation of aerobic cultures of an Arthrobacter species with near-UV light and oxygen induced synthesis of a cell surface protein, M/sub r/ 21,000 polypeptide. Visible light, oxygen and a sensitizing dye were also effective in induction. Far-UV light, bleomycin and nalidixic acid, all inducers of the recA protein in Escherichia coli, were ineffective inducers of this protein. Furthermore, X-irradiation and radical-generating oxidants failed to induce synthesis of the M/sub r/ 21,000 polypeptide. DNA binding dyes proved to be capable of inducing synthesis of this protein or inhibiting dye-mediated stimulation of synthesis of this protein. For example, dGdC-specific dyes (e.g. methylene blue, neutral red, acridine orange or ethidium bromide) were efficient inducers of the M/sub r/ 21,000 polypeptide. Also methylene blue and neutral red were more efficient inducers than were acridine orange or ethidium bromide, which could be explained by the greater dGdC specificity and, possibly by the greater photoreactivity of methylene blue and neutral red. dAdT-specific dyes such as methyl green or daunomycin effectively inhibited dye-mediated induction. Rose bengal is an anionic dye which does not bind to DNA but does mediate the photooxidation of deoxyguanosine residues in DNA. It is an efficient inducer of the M/sub r/ 21,000 polypeptide. Induction with this dye is nearly eliminated when novobiocin, an inhibitor of DNA gyrase (topoisomerase II) which mediates relaxation, is added in conjunction with rose bengal

  6. Induction of a M/sub r/ 21,000 polypeptide in an Arthrobacter Sp. by dye-sensitized photooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Franzi, J.J.

    1985-01-01

    Irradiation of aerobic cultures of an Arthrobacter species with near-UV light and oxygen induced synthesis of a cell surface protein, M/sub r/ 21,000 polypeptide. Visible light, oxygen and a sensitizing dye were also effective in induction. Far-UV light, bleomycin and nalidixic acid, all inducers of the recA protein in Escherichia coli, were ineffective inducers of this protein. Furthermore, X-irradiation and radical-generating oxidants failed to induce synthesis of the M/sub r/ 21,000 polypeptide. DNA binding dyes proved to be capable of inducing synthesis of this protein or inhibiting dye-mediated stimulation of synthesis of this protein. For example, dGdC-specific dyes (e.g. methylene blue, neutral red, acridine orange or ethidium bromide) were efficient inducers of the M/sub r/ 21,000 polypeptide. Also methylene blue and neutral red were more efficient inducers than were acridine orange or ethidium bromide, which could be explained by the greater dGdC specificity and, possibly by the greater photoreactivity of methylene blue and neutral red. dAdT-specific dyes such as methyl green or daunomycin effectively inhibited dye-mediated induction. Rose bengal is an anionic dye which does not bind to DNA but does mediate the photooxidation of deoxyguanosine residues in DNA. It is an efficient inducer of the M/sub r/ 21,000 polypeptide. Induction with this dye is nearly eliminated when novobiocin, an inhibitor of DNA gyrase (topoisomerase II) which mediates relaxation, is added in conjunction with rose bengal.

  7. Enhanced U(VI) release from autunite mineral by aerobic Arthrobacter sp. in the presence of aqueous bicarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Katsenovich, Yelena P.; Carvajal, Denny A.; Wellman, Dawn M.; Lagos, Leonel E.

    2012-05-01

    The bacterial effect on U(VI) release from the autunite mineral (Ca[(UO2)(PO4)]2•3H2O) was investigated to provide a more comprehensive understanding of the important microbiological processes affecting autunite stability within subsurface bicarbonate-bearing environments. Experiments were performed in a culture of the Arthrobacter oxydans G975 strain, herein referred to as G975, a soil bacterium previously isolated from Hanford Site soil. 91 mg of autunite powder and 50 mL of phosphorous-limiting sterile media were amended with bicarbonate (ranging between 1 and 10 mM) in glass reactor bottles and inoculated with the G975 strain after the dissolution of autunite was at steady state. SEM observations indicated that G975 formed a biofilm on the autunite surface and penetrated the mineral cleavages. The mineral surface colonization by bacteria tended to increase concomitantly with bicarbonate concentrations. Additionally, a sterile culture-ware with inserts was used in non-contact dissolution experiments where autunite and bacteria cells were kept separately. The data suggest that G975 bacteria is able to enhance the release of U(VI) from autunite without direct contact with the mineral. In the presence of bicarbonate, the damage to bacterial cells caused by U(VI) toxicity was reduced, yielding similar values for total organic carbon (TOC) degradation and cell density compared to U(VI)-free controls. The presence of active bacterial cells greatly enhanced the release of U(VI) from autunite in bicarbonate-amended media.

  8. Enhanced U(VI) release from autunite mineral by aerobic Arthrobacter sp. in the presence of aqueous bicarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Katsenovich, Yelena; Carvajal, Denny A.; Wellman, Dawn M.; Lagos, Leonel

    2012-04-20

    The bacterial effect on U(VI) leaching from the autunite mineral (Ca[(UO{sub 2})(PO{sub 4})]{sub 2} {center_dot} 3H{sub 2}O) was investigated to provide a more comprehensive understanding into important microbiological processes affecting autunite stability within subsurface bicarbonate-bearing environments. Experiments were performed in a culture of G975 Arthrobacter oxydans strain, herein referred to as G975, a soil bacterium previously isolated from Hanford Site soil. 91 mg of autunite powder and 50 mL of phosphorus-limiting sterile media were amended with bicarbonate ranging between 1-10 mM in glass reactor bottles and inoculated with G975 strain after the dissolution of autunite was at steady state. SEM observations indicated G975 formed a biofilm on the autunite surface and penetrated the mineral cleavages. The mineral surface colonization by bacteria tended to increase concomitantly with bicarbonate concentrations. Additionally, a sterile cultureware with inserts was used in non-contact bioleaching experiments where autunite and bacteria cells were kept separately. The data suggest the G975 bacteria is able to enhance U(VI) leaching from autunite without the direct contact with the mineral. In the presence of bicarbonate, the damage to bacterial cells caused by U(VI) toxicity was reduced, yielding similar values for total organic carbon (TOC) degradation and cell density compared to U(VI)-free controls. The presence of active bacterial cells greatly enhanced the U(VI) bioleaching from autunite in bicarbonate-amended media.

  9. Sphingomonas antarctica sp. nov., isolated from Antarctic tundra soil.

    Science.gov (United States)

    Huang, Yao; Wei, Ziyan; Danzeng, Wangmu; Kim, Myong Chol; Zhu, Guoxin; Zhang, Yumin; Liu, Zuobing; Peng, Fang

    2017-10-01

    Strain 200 T , isolated from a soil sample taken from Antarctic tundra soil around Zhongshan Station, was found to be a Gram-stain-negative, yellow-pigmented, catalase-positive, oxidase-negative, non-motile, non-spore-forming, rod-shaped and aerobic bacterium. Strain 200 T grew optimally at pH 7.0 and in the absence of NaCl on R2A. Its optimum growth temperature was 20 °C. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 200 T belonged to the genus Sphingomonas. Strain 200 T showed the highest sequence similarities to Sphingomonas kyeonggiense THG-DT81 T (95.1 %) and Sphingomonas molluscorum KMM 3882 T (95.1 %). Chemotaxonomic analysis showed that strain 200 T had characteristics typical of members of the genus Sphingomonas. Ubiquinone 10 was the predominant respiratory quinone and sym-homospermidine was the polyamine. The major polar lipids were sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and phosphatidylcholine. The G+C content of the genomic DNA was determined to be 60.9 mol%. Strain 200 T contained C16 : 0 (31.6 %), summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c, 22.7 %), summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c, 11.2 %), C18 : 0 (7.8 %) and C14 : 0 2OH (6.7 %) as the major cellular fatty acids. On the basis of phylogenetic analysis, and physiological and biochemical characterization, strain 200 T should be classified as representing a novel species of the genus Sphingomonas, for which the name Sphingomonasantarctica sp. nov. is proposed. The type strain is 200 T (=CCTCC AB 2016064 T =KCTC 52488 T ).

  10. Physiological and Comparative Genomic Analysis of Arthrobacter sp. SRS-W-1-2016 Provides Insights on Niche Adaptation for Survival in Uraniferous Soils.

    Science.gov (United States)

    Chauhan, Ashvini; Pathak, Ashish; Jaswal, Rajneesh; Edwards, Bobby; Chappell, Demario; Ball, Christopher; Garcia-Sillas, Reyna; Stothard, Paul; Seaman, John

    2018-01-11

    Arthrobacter sp. strain SRS-W-1-2016 was isolated on high concentrations of uranium (U) from the Savannah River Site (SRS) that remains co-contaminated by radionuclides, heavy metals, and organics. SRS is located on the northeast bank of the Savannah River (South Carolina, USA), which is a U.S. Department of Energy (DOE) managed ecosystem left historically contaminated from decades of nuclear weapons production activities. Predominant contaminants within the impacted SRS environment include U and Nickel (Ni), both of which can be transformed microbially into less toxic forms via metal complexation mechanisms. Strain SRS-W-1-2016 was isolated from the uraniferous SRS soils on high concentrations of U (4200 μM) and Ni (8500 μM), but rapid growth was observed at much lower concentrations of 500 μM U and 1000 μM Ni, respectively. Microcosm studies established with strain SRS-W-1-2016 revealed a rapid decline in the concentration of spiked U such that it was almost undetectable in the supernatant by 72 h of incubation. Conversely, Ni concentrations remained unchanged, suggesting that the strain removed U but not Ni under the tested conditions. To obtain a deeper understanding of the metabolic potential, a draft genome sequence of strain SRS-W-1-2016 was obtained at a coverage of 90×, assembling into 93 contigs with an N50 contig length of 92,788 bases. The genomic size of strain SRS-W-1-2016 was found to be 4,564,701 bases with a total number of 4327 putative genes. An in-depth, genome-wide comparison between strain SRS-W-1-2016 and its four closest taxonomic relatives revealed 1159 distinct genes, representing 26.7% of its total genome; many associating with metal resistance proteins (e.g., for cadmium, cobalt, and zinc), transporter proteins, stress proteins, cytochromes, and drug resistance functions. Additionally, several gene homologues coding for resistance to metals were identified in the strain, such as outer membrane efflux pump proteins, peptide

  11. Physiological and Comparative Genomic Analysis of Arthrobacter sp. SRS-W-1-2016 Provides Insights on Niche Adaptation for Survival in Uraniferous Soils

    Directory of Open Access Journals (Sweden)

    Ashvini Chauhan

    2018-01-01

    Full Text Available Arthrobacter sp. strain SRS-W-1-2016 was isolated on high concentrations of uranium (U from the Savannah River Site (SRS that remains co-contaminated by radionuclides, heavy metals, and organics. SRS is located on the northeast bank of the Savannah River (South Carolina, USA, which is a U.S. Department of Energy (DOE managed ecosystem left historically contaminated from decades of nuclear weapons production activities. Predominant contaminants within the impacted SRS environment include U and Nickel (Ni, both of which can be transformed microbially into less toxic forms via metal complexation mechanisms. Strain SRS-W-1-2016 was isolated from the uraniferous SRS soils on high concentrations of U (4200 μM and Ni (8500 μM, but rapid growth was observed at much lower concentrations of 500 μM U and 1000 μM Ni, respectively. Microcosm studies established with strain SRS-W-1-2016 revealed a rapid decline in the concentration of spiked U such that it was almost undetectable in the supernatant by 72 h of incubation. Conversely, Ni concentrations remained unchanged, suggesting that the strain removed U but not Ni under the tested conditions. To obtain a deeper understanding of the metabolic potential, a draft genome sequence of strain SRS-W-1-2016 was obtained at a coverage of 90×, assembling into 93 contigs with an N50 contig length of 92,788 bases. The genomic size of strain SRS-W-1-2016 was found to be 4,564,701 bases with a total number of 4327 putative genes. An in-depth, genome-wide comparison between strain SRS-W-1-2016 and its four closest taxonomic relatives revealed 1159 distinct genes, representing 26.7% of its total genome; many associating with metal resistance proteins (e.g., for cadmium, cobalt, and zinc, transporter proteins, stress proteins, cytochromes, and drug resistance functions. Additionally, several gene homologues coding for resistance to metals were identified in the strain, such as outer membrane efflux pump proteins

  12. Four novel Arthrobacter species isolated from filtration substrate.

    Science.gov (United States)

    Ding, Linxian; Hirose, Taketo; Yokota, Akira

    2009-04-01

    Four Gram-positive, non-motile, non-spore-forming bacterial strains, LC4(T), LC6(T), LC10(T) and LC13(T), were isolated from a filtration substrate made from trass, a volcanic rock, and their taxonomic positions were investigated by a polyphasic taxonomic approach. The novel strains grew over a temperature range of 5-40 degrees C, at pH values of 6-11 and in the presence of 3-7 % (w/v) NaCl. A phylogenetic tree based on 16S rRNA gene sequences showed the novel strains formed a distinct evolutionary lineage within the genus Arthrobacter. Chemotaxonomic analyses demonstrated that the major menaquinone was MK-9(H(2)), a menaquinone typical of the Arthrobacter globiformis group. The major fatty acid was anteiso-C(15 : 0) and the major amino acid present in the cell-wall peptidoglycan was l-lysine. These observations supported the affiliation of the novel strains to the genus Arthrobacter. On the basis of their morphological, physiological and genotypic characteristics, the new isolates are considered to represent four novel species of the genus Arthrobacter, for which the names Arthrobacter niigatensis sp. nov. (type strain LC4(T)=IAM 15382(T)=CCTCC AB 206012(T)), Arthrobacter alkaliphilus sp. nov. (type strain LC6(T)=IAM 15383(T)=CCTCC AB 206013(T)), Arthrobacter echigonensis sp. nov. (type strain LC10(T)=IAM 15385(T)=CCTCC AB 206017(T)) and Arthrobacter albidus sp. nov. (type strain LC13(T)=IAM 15386(T)=CCTCC AB 206018(T)) are proposed.

  13. Investigating trehalose synthesis genes after cold acclimation in the Antarctic nematode Panagrolaimus sp. DAW1

    Directory of Open Access Journals (Sweden)

    Anna C. Seybold

    2017-12-01

    Full Text Available Panagrolaimus sp. DAW1 is a freeze-tolerant Antarctic nematode which survives extensive intracellular ice formation. The molecular mechanisms of this extreme adaptation are still poorly understood. We recently showed that desiccation-enhanced RNA interference (RNAi soaking can be used in conjunction with quantitative polymerase chain reaction (qPCR to screen for phenotypes associated with reduced expression of candidate genes in Panagrolaimus sp. DAW1. Here, we present the use of this approach to investigate the role of trehalose synthesis genes in this remarkable organism. Previous studies have shown that acclimating Panagrolaimus sp. DAW1 at 5°C before freezing or desiccation substantially enhances survival. In this study, the expression of tps-2 and other genes associated with trehalose metabolism, as well as lea-1, hsp-70 and gpx-1, in cold-acclimated and non-acclimated nematodes was analyzed using qPCR. Pd-tps-2 and Pd-lea-1 were significantly upregulated after cold acclimation, indicating an inducible expression in the cold adaptation of Panagrolaimus sp. DAW1. The role of trehalose synthesis genes in Panagrolaimus sp. DAW1 was further investigated by RNAi. Compared to the controls, Pd-tps-2a(RNAi-treated and cold-acclimated nematodes showed a significant decrease in mRNA, but no change in trehalose content or freezing survival. The involvement of two other trehalose synthesis genes (tps-2b and gob-1 was also investigated. These findings provide the first functional genomic investigation of trehalose synthesis genes in the non-model organism Panagrolaimus sp. DAW1. The presence of several trehalose synthesis genes with different RNAi sensitivities suggests the existence of multiple backup systems in Panagrolaimus sp. DAW1, underlining the importance of this sugar in preparation for freezing.

  14. UV and cold tolerance of a pigment-producing Antarctic Janthinobacterium sp. Ant5-2

    KAUST Repository

    Mojib, Nazia

    2013-03-20

    In this paper, we describe the UV and cold tolerance of a purple violet pigment (PVP)-producing Antarctic bacterium, Janthinobacterium sp. Ant5-2 (PVP+) and compared its physiological adaptations with a pigmentless mutant strain (PVP-). A spontaneous deletion of vioA that codes for tryptophan monooxygenase, the first gene involved in the biosynthesis of PVP was found in PVP- strain. The PVP- culture exhibited significantly reduced survival during exponential and stationary growth phase following exposure to UVB (320 nm) and UVC (254 nm) (dose range: 0-300 J/m2) when compared to wild-type (PVP+) cultures. In addition, upon biochemical inhibition of pigment synthesis by 2(5H)-furanone, wild-type PVP+ cultures exhibited approximately 50-fold growth reduction at a higher dose (300 J/m2) of UV. Increased resistance to UV was observed upon inducing starvation state in both PVP+ and PVP- cultures. There was 80 % (SD = ±8) reduction in extrapolymeric substance (EPS) production in the PVP- cultures along with a compromised survival to freeze-thaw cycles when compared to the PVP+ cultures. Perhaps synthesis of PVP and EPS are among the key adaptive features that define the survival of this bacterium in Antarctic extreme conditions, especially during austral summer months. © 2013 Springer Japan.

  15. Degradation of the Phosphonate Herbicide Glyphosate by Arthrobacter atrocyaneus ATCC 13752

    OpenAIRE

    Pipke, Rüdiger; Amrhein, Nikolaus

    1988-01-01

    Of nine authentic Arthrobacter strains tested, only A. atrocyaneus ATCC 13752 was capable of using the herbicide glyphosate [N-(phosphonomethyl)glycine] as its sole source of phosphorus. Contrary to the previously isolated Arthrobacter sp. strain GLP-1, which degrades glyphosate via sarcosine, A. atrocyaneus metabolized glyphosate to aminomethylphosphonic acid. The carbon of aminomethylphosphonic acid was entirely converted to CO2. This is the first report on glyphosate degradation by a bacte...

  16. New Cysteine-Rich Ice-Binding Protein Secreted from Antarctic Microalga, Chloromonas sp.

    Science.gov (United States)

    Jung, Woongsic; Campbell, Robert L; Gwak, Yunho; Kim, Jong Im; Davies, Peter L; Jin, EonSeon

    2016-01-01

    Many microorganisms in Antarctica survive in the cold environment there by producing ice-binding proteins (IBPs) to control the growth of ice around them. An IBP from the Antarctic freshwater microalga, Chloromonas sp., was identified and characterized. The length of the Chloromonas sp. IBP (ChloroIBP) gene was 3.2 kb with 12 exons, and the molecular weight of the protein deduced from the ChloroIBP cDNA was 34.0 kDa. Expression of the ChloroIBP gene was up- and down-regulated by freezing and warming conditions, respectively. Western blot analysis revealed that native ChloroIBP was secreted into the culture medium. This protein has fifteen cysteines and is extensively disulfide bonded as shown by in-gel mobility shifts between oxidizing and reducing conditions. The open-reading frame of ChloroIBP was cloned and over-expressed in Escherichia coli to investigate the IBP's biochemical characteristics. Recombinant ChloroIBP produced as a fusion protein with thioredoxin was purified by affinity chromatography and formed single ice crystals of a dendritic shape with a thermal hysteresis activity of 0.4±0.02°C at a concentration of 5 mg/ml. In silico structural modeling indicated that the three-dimensional structure of ChloroIBP was that of a right-handed β-helix. Site-directed mutagenesis of ChloroIBP showed that a conserved region of six parallel T-X-T motifs on the β-2 face was the ice-binding region, as predicted from the model. In addition to disulfide bonding, hydrophobic interactions between inward-pointing residues on the β-1 and β-2 faces, in the region of ice-binding motifs, were crucial to maintaining the structural conformation of ice-binding site and the ice-binding activity of ChloroIBP.

  17. Extracellular polymeric substances with metal adsorption capacity produced by Pseudoalteromonas sp. MER144 from Antarctic seawater.

    Science.gov (United States)

    Caruso, Consolazione; Rizzo, Carmen; Mangano, Santina; Poli, Annarita; Di Donato, Paola; Nicolaus, Barbara; Di Marco, Gaetano; Michaud, Luigi; Lo Giudice, Angelina

    2018-02-01

    The EPS-producing Pseudoalteromonas sp. MER144 was selected among 606 isolates from Antarctic seawater due to its evident slimy appearance on agar plates. The production of EPSs was enhanced by a step-by-step approach varying the carbon source, substrate and NaCl concentrations, temperature, and pH. Optimal conditions for the EPS production resulted at temperature of 4 °C and pH 7, with addition of 2% sucrose (w/v) and 3% NaCl (w/v). EPSs produced under optimal conditions were chemically characterized, resulting in a moderate carbohydrate content (35%), uronic acids (14%), and proteins (12%). Monosaccharide composition was estimated to be Glu:Man:GluN:Ara:GluA:GalA:Gal (1:0.36:0.26:0.06:0.06:0.05:0.03), while the estimated molecular weight was about 250 kDa. The addition of sucrose in the culture medium, by stimulating the EPS production, allowed MER144 to tolerate higher concentrations of mercury and cadmium. This finding was probably dependent on the presence of uronic acids and sulfate groups, which can bind cations, in the extracted EPSs. Monitoring EPS production under optimal conditions at different concentrations of mercury and cadmium revealed that EPS amounts increased at increasing heavy metal concentrations, indicating an adaptation to the stress conditions tested.

  18. Cloning, overexpression, and characterization of a thermostable nitrilase from an Antarctic Pyrococcus sp.

    Science.gov (United States)

    Cabrera, Ma Ángeles; Blamey, Jenny M

    2017-09-01

    Nitriles are important chemical building blocks for the synthesis of intermediates in fine chemical and pharmaceutical industries. Here, we report a new highly thermostable nitrilase from an Antarctic Pyrococcus sp. MC-FB, a hyperthermophilic archaeon. A gene that encoded a nitrilase was identified and subsequently cloned and overexpressed in Escherichia coli. The recombinant nitrilase, named NitMC-FB, is active as a homodimer (60 kDa) with an optimal temperature and pH of 90 °C and 7.0, respectively. NitMC-FB hydrolyzes preferentially aromatic nitriles, being the first aromatic nitrilase from an archaeon described so far. The K M and V max parameters were determined to be 13.9 mM and 3.7 μmol/min*mg, respectively, with 2-cyanopyridine as the substrate. Additionally, the recombinant nitrilase is highly thermostable with a half-life of 8 h at 90 °C.

  19. Expression and enzymatic characterization of a cold-adapted β-agarase from Antarctic bacterium Pseudoalteromonas sp. NJ21

    Science.gov (United States)

    Li, Jiang; Sha, Yujie

    2015-03-01

    An agar-degrading bacterium, designated as Pseudoalteromonas sp. NJ21, was isolated from an Antarctic sediment sample. The agarase gene aga1161 from Pseudoalteromonas sp. NJ21 consisting of a 2 382-bp coding region was cloned. The gene encodes a 793-amino acids protein and was found to possess characteristic features of the Glyco_hydro_42 family. The recombinant agarase (rAga1161) was overexpressed in Escherichia coli and purified as a fusion protein. Enzyme activity analysis revealed that the optimum temperature and pH for the purified recombinant agarase were 30-40°C and 8.0, respectively. rAga1161 was found to maintain as much as 80% of its maximum activity at 10°C, which is typical of a coldadapted enzyme. The pattern of agar hydrolysis demonstrated that the enzyme is an β-agarase, producing neoagarobiose (NA2) as the final main product. Furthermore, this work is the first proof of an agarolytic activity in Antarctic bacteria and these results indicate the potential for the Antarctic agarase as a catalyst in medicine, food and cosmetic industries.

  20. Effect of vertical mixing on short-term mycosporine-like amino acid synthesis in the Antarctic diatom, Thalasiossira sp.

    Directory of Open Access Journals (Sweden)

    Marcelo Pablo Hernando

    2011-12-01

    Full Text Available One of the adaptations whereby phytoplankton can alleviate damage induced by ultraviolet radiation (280-400 nm is the synthesis of mycosporine-like amino acids (MAAs. The synthesis of MAAs was studied after exposure of the Antarctic diatom Thalassiosira sp. isolated from Potter Cove (South Shetland Is., Antarctica to 2 treatments with a solar simulator: surface (Sfix and vertical mixing (Mix irradiance conditions. Light exposure was simulated in daily cycles with maximum irradiance at noon. Only 2 MAAs, Porphyra-334 (82-85% and Shinorine (15-18%, were identified. The concentration of the two compounds increased during experimental light exposure (50-55% and declined in the dark (10-15%. During the light period the synthesis rate of MAAs per unit of chlorophyll a was higher in the Sfix treatment (µ=0.17 h-1 than in the Mix treatment (µ=0.05 h-1. In spite of the higher MAA levels, low cell numbers were observed in the Sfix treatment, suggesting that the algae synthesized photoprotective compounds at the expense of growth. Our results document overlapping effects of both daily light cycles and vertical mixing affecting the synthesis of MAAs. This, and the high thermal dissipation of the ultraviolet B radiation energy (280-320 nm absorbed by these substances, suggest a rapid photoadaptive response of Thalasiossira sp. upon exposure to elevated irradiance in a stratified water column, as well as the complementary role of vertical mixing in photo-protection.

  1. The effect of UV radiation on photosynthesis in an Antarctic diatom (Thalassiosira sp.): does vertical mixing matter?

    International Nuclear Information System (INIS)

    Hernando, Marcelo P.; Ferreyra, Gustavo A.

    2004-01-01

    Full text: The reduction of the Antarctic stratospheric ozone resulted in significant increases in ultraviolet B radiation (UVBR, 280-320 nm) reaching the surface of the ocean. A series of laboratory and field experiments were conducted at Potter Cove (25 de Mayo Is., South Shetland Is., Antarctica) to study the effects of UVBR on photosynthesis of a typical Antarctic bloom forming diatom (Thalassiosira sp.) in fixed and moving incubations. There were three irradiance treatments: PART (with only photosynthetic active radiation, PAR, 400- 700 nm), UVAT (with PAR and ultraviolet A radiation, UVAR, 320-400 nm) and UVBT (with PAR, UVAR and UVBR). The three treatments were incubated in the field and laboratory with a solar simulator (SOLSI) in fixed frames at 0.5 and 5 m depth (S fix and B fix , respectively), while for the moving incubations were done within 6 h cycles (Mix). Considering the field and laboratory pooled data, results suggest an overall 45-50 % photosynthesis inhibition of S fix incubations in relation with Mix ones. During SOLSI experiments no significant differences were found between irradiance treatments under normal and medium ozone concentrations. Under low ozone conditions, a 40 % reduction in photosynthesis was observed in the UVBT for S fix . In contrast, no significant differences were observed between the irradiance treatments for Mix. Field experiment showed results similar to the laboratory ones, but in this case not only S fix but Mix incubations presented a significant reduction in photosynthesis under low ozone. The differences between laboratory and field experiments are discussed in terms of the relative significance of UVBR dose and dose rate on both types of experiments. (author)

  2. Arthrobacter globiformis and its bacteriophage in soil

    Science.gov (United States)

    Casida, L. E., Jr.; Liu, K.-C.

    1974-01-01

    An attempt was made to correlate bacteriophages for Arthrobacter globiformis with soils containing that bacterium. The phages were not detected unless the soil was nutritionally amended (with glucose or sucrose) and incubated for several days. Phage was continuously produced after amendment without the addition of host Arthrobacter. These results indicate that the bacteriophage is present in a masked state and that the bacteria are present in an insensitive form which becomes sensitive after addition of nutrient.

  3. Purification and biochemical characterization of a cold-active lipase from Antarctic sea ice bacteria Pseudoalteromonas sp. NJ 70.

    Science.gov (United States)

    Wang, Quanfu; Hou, Yanhua; Ding, Yu; Yan, Peisheng

    2012-09-01

    An extracellular cold-active lipase from Antarctic sea ice bacteria Pseudoalteromonas sp. NJ 70 was purified and characterized. The overall purification based on lipase activity was 27.5-fold with a yield of 25.4 %. The purified lipase showed as a single band on SDS-PAGE with an apparent molecular weight of 37 kDa. The optimum temperature and pH were 35 °C and 7.0, respectively. The lipase activity was enhanced by Ca(2+) and Mg(2+), while was partially inhibited by other metals such as Cu(2+), Zn(2+), Ba(2+), Pb(2+), Fe(2+) and Mn(2+). The lipase had high tolerance to a wide range of NaCl concentrations (0-2 M NaCl). It exhibited high levels of activity in the presence of DTT, Thiourea, H(2)O(2) as well as in the presence of various detergents such as Span 60, Tween-80, Triton X-100. In addition, the lipase showed a preference for long-chain p-nitrophenyl esters (C(12)-C(18)). These results indicated that this lipase could be a novel cold-active lipase.

  4. Cloning, Expression, Purification, and Characterization of Glutaredoxin from Antarctic Sea-Ice Bacterium Pseudoalteromonas sp. AN178

    Directory of Open Access Journals (Sweden)

    Quanfu Wang

    2014-01-01

    Full Text Available Glutaredoxins (Grxs are small ubiquitous redox enzymes that catalyze glutathione-dependent reactions to reduce protein disulfide. In this study, a full-length Grx gene (PsGrx with 270 nucleotides was isolated from Antarctic sea-ice bacterium Pseudoalteromonas sp. AN178. It encoded deduced 89 amino acid residues with the molecular weight 9.8 kDa. Sequence analysis of the amino acid sequence revealed the catalytic motif CPYC. Recombinant PsGrx (rPsGrx stably expressed in E. coli BL21 was purified to apparent homogeneity by Ni-affinity chromatography. rPsGrx exhibited optimal activity at 30°C and pH 8.0 and showed 25.5% of the activity at 0°C. It retained 65.0% of activity after incubation at 40°C for 20 min and still exhibited 37.0% activity in 1.0 M NaCl. These results indicated that rPsGrx was a typical cold active protein with low thermostability.

  5. New emulsifying and cryoprotective exopolysaccharide from Antarctic Pseudomonas sp. ID1.

    Science.gov (United States)

    Carrión, Ornella; Delgado, Lidia; Mercade, Elena

    2015-03-06

    Pseudomonas sp. ID1 is a cold-adapted bacterium isolated from a marine sediment sample collected from South Shetland Islands (Antarctica) that is noted for the highly mucous appearance of its colonies. In this work, we have characterized an exopolysaccharide (EPS) produced by this strain, which is mainly composed of glucose, galactose and fucose, and has a molecular mass higher than 2×10(6) Da. We have also studied its potential biotechnological applications as an emulsifier and cryoprotectant agent. The EPS emulsifying activity against different food and cosmetic oils was much higher than commercial gums such as xanthan gum and arabic gum, and surfarctants such as Span 20. It formed highly stable emulsions against the cosmetic oil cetiol V, exhibiting pseudoplastic flow behavior, low thixotrophy and yield stress. The EPS of Pseudomonas sp. ID1 conferred significant cryoprotection for the strain itself as well as for other bacteria, including Escherichia coli, suggesting a universal cryoprotectant role. The cryoprotective activity of the EPS showed a clear dose-response relation at -20 °C and -80 °C and was significantly higher than that observed for the membrane stabilizer fetal bovine serum (FBS). These properties make the EPS of Pseudomonas sp. ID1 a promising alternative to commercial polysaccharides as an emulsifier and cryoprotectant agent for food, pharmaceutical and cosmetic industries. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Responses of seabirds, in particular prions (Pachyptila sp.), to small-scale processes in the Antarctic Polar Front

    NARCIS (Netherlands)

    van Franeker, JA; van den Brink, NW; Bathmann, UV; Pollard, RT; de Barr, HJW; Wolff, WJ; Brink, Nico W. van den; Bathmann, Ulrich V.; Pollard, Raymond T.; Baar, Hein J.W. de; Wolff, Wim J.

    2002-01-01

    Small-scale distribution patterns of seabirds in the Antarctic Polar Front (APF) were investigated in relation to other biological, physical, and chemical features during the ANT-XIII/2 research cruise of R.V. Polarstern from December 1995 to January 1996. The APF is characterized by steep gradients

  7. Long-term experiment on physiological responses to synergetic effects of ocean acidification and photoperiod in the Antarctic sea ice algae Chlamydomonas sp. ICE-L.

    Science.gov (United States)

    Xu, Dong; Wang, Yitao; Fan, Xiao; Wang, Dongsheng; Ye, Naihao; Zhang, Xiaowen; Mou, Shanli; Guan, Zheng; Zhuang, Zhimeng

    2014-07-15

    Studies on ocean acidification have mostly been based on short-term experiments of low latitude with few investigations of the long-term influence on sea ice communities. Here, the combined effects of ocean acidification and photoperiod on the physiological response of the Antarctic sea ice microalgae Chlamydomonas sp. ICE-L were examined. There was a general increase in growth, PSII photosynthetic parameters, and N and P uptake in continuous light, compared to those exposed to regular dark and light cycles. Elevated pCO2 showed no consistent effect on growth rate (p=0.8) and N uptake (p=0.38) during exponential phrase, depending on the photoperiod but had a positive effect on PSII photosynthetic capacity and P uptake. Continuous dark reduced growth, photosynthesis, and nutrient uptake. Moreover, intracellular lipid, mainly in the form of PUFA, was consumed at 80% and 63% in low and high pCO2 in darkness. However, long-term culture under high pCO2 gave a more significant inhibition of growth and Fv/Fm to high light stress. In summary, ocean acidification may have significant effects on Chlamydomonas sp. ICE-L survival in polar winter. The current study contributes to an understanding of how a sea ice algae-based community may respond to global climate change at high latitudes.

  8. Effects of ocean acidification on the physiological performance and carbon production of the Antarctic sea ice diatom Nitzschia sp. ICE-H.

    Science.gov (United States)

    Qu, Chang-Feng; Liu, Fang-Ming; Zheng, Zhou; Wang, Yi-Bin; Li, Xue-Gang; Yuan, Hua-Mao; Li, Ning; An, Mei-Ling; Wang, Xi-Xi; He, Ying-Ying; Li, Lu-Lu; Miao, Jin-Lai

    2017-07-15

    Ocean acidification (OA) resulting from increasing atmospheric CO 2 strongly influences marine ecosystems, particularly in the polar ocean due to greater CO 2 solubility. Here, we grew the Antarctic sea ice diatom Nitzschia sp. ICE-H in a semicontinuous culture under low (~400ppm) and high (1000ppm) CO 2 levels. Elevated CO 2 resulted in a stimulated physiological response including increased growth rates, chlorophyll a contents, and nitrogen and phosphorus uptake rates. Furthermore, high CO 2 enhanced cellular particulate organic carbon production rates, indicating a greater shift from inorganic to organic carbon. However, the cultures grown in high CO 2 conditions exhibited a decrease in both extracellular and intracellular carbonic anhydrase activity, suggesting that the carbon concentrating mechanisms of Nitzschia sp. ICE-H may be suppressed by elevated CO 2 . Our results revealed that OA would be beneficial to the survival of this sea ice diatom strain, with broad implications for global carbon cycles in the future ocean. Copyright © 2017. Published by Elsevier Ltd.

  9. Effects of iron and light stress on the biochemical composition of Antarctic Phaeocystis sp. (Prymnesiophyceae). II. Pigment composition

    NARCIS (Netherlands)

    van Leeuwe, MA; Stefels, J

    A strain of Phaeocystis sp., isolated in the Southern Ocean, was cultured under iron- and light-limited conditions. The cellular content of chlorophyll a and accessory light-harvesting (LH) pigments increased under low light intensities. Iron limitation resulted in a decrease of all light-harvesting

  10. Antimicrobial activity of PVP from an Antarctic bacterium, Janthinobacterium sp. Ant5-2, on multi-drug and methicillin resistant Staphylococcus aureus

    KAUST Repository

    Huang, Jonathan P.

    2012-04-11

    Multiple drug resistant (MDR) and methicillin-resistant Staphylococcus aureus (MRSA) have become increasingly prevalent as a community acquired infection. As a result limited treatment options are available with conventional synthetic antibiotics. Bioprospecting natural products with potent antimicrobial activity show promise for developing new drugs against this pathogen. In this study, we have investigated the antimicrobial activity of a purple violet pigment (PVP) from an Antarctic bacterium, Janthinobacterium sp. Ant5-2 on 15 clinical MDR and MRSA strains. The colorimetric resazurin assay was employed to determine the minimum inhibitory concentration (MIC90) of PVP against MDR and MRSA. The MIC90 ranged between 1.57 µg/mL and 3.13 µg/mL, which are significantly lower than many antimicrobials tested from natural sources against this pathogen. The spectrophotometrically determined growth analysis and total microscopic counts using Live/dead® BacLight™ fluorescent stain exhibited a steady decrease in viability of both MDR and MRSA cultures following treatment with PVP at the MIC levels. In silico predictive molecular docking study revealed that PVP could be a DNA-targeting minor groove binding antimicrobial compound. The continued development of novel antimicrobials derived from natural sources with the combination of a suite of conventional antibiotics could stem the rising pandemic of MDR and MRSA along with other deadly microbial pathogens.

  11. Antibacterial activity of the Antarctic bacterium Janthinobacterium sp. SMN 33.6 against multi-resistant Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Geraldine Asencio

    2014-01-01

    Conclusions: The ethanolic extract of Janthinobacterium sp. SMN 33.6 possesses antibacterial activity against a chromosomal AmpC beta-lactamase-producing strain of Serratia marcescens, an extended-spectrum beta-lactamase-producing Escherichia coli and also against carbapenemase-producing strains of Acinetobacter baumannii and Pseudomonas aeruginosa. This becomes a potential and interesting biotechnological tool for the control of bacteria with multi-resistance to commonly used antibiotics.

  12. Screening of degradative plasmids from Arthrobacter sp. HW08 and ...

    African Journals Online (AJOL)

    Administrator

    2011-06-08

    Jun 8, 2011 ... restriction digestion of genomic DNA and pUC19 vector, ligation and transformation into DH5α. Five plasmids of different sizes were ... endophytic fungi (Braun et al., 2003; Pryor et al., 2009;. Ralphs et al., 2008; Yu et al., ... soil, and six months later extracted and identified two strains of bacteria which were ...

  13. Arthrobacter enclensis sp. nov., isolated from sediment sample

    Digital Repository Service at National Institute of Oceanography (India)

    Dastager, S.G.; Qin, L.; Tang, S.K.; Krishnamurthi, S.; Lee, J.C.; Li, W.J.

    using CLUSTAL_X (Thompson et al. 1997). The phylogenetic trees were constructed using the neighbour-joining (Saitou and Nei 1987), maximum-parsimony (Fitch and Margoliash 1967) and maximum-likelihood (Felsenstein 1981) tree-making algorithm software... packages MEGA version 4.0 (Tamura et al. 2007), PHYLIP version 3.6 (Felsenstein 2002) and PHYML (Guindon and Gascuel 2003). The topologies of the phylogenetic trees were evaluated using the boot- strap resampling method of Felsenstein (1985) with 1...

  14. Molecular Cloning and Functional Expression of a Δ9- Fatty Acid Desaturase from an Antarctic Pseudomonas sp. A3

    Science.gov (United States)

    Garba, Lawal; Mohamad Ali, Mohd Shukuri; Oslan, Siti Nurbaya; Rahman, Raja Noor Zaliha Raja Abd

    2016-01-01

    Fatty acid desaturase enzymes play an essential role in the synthesis of unsaturated fatty acids. Pseudomonas sp. A3 was found to produce a large amount of palmitoleic and oleic acids after incubation at low temperatures. Using polymerase Chain Reaction (PCR), a novel Δ9- fatty acid desaturase gene was isolated, cloned, and successfully expressed in Escherichia coli. The gene was designated as PA3FAD9 and has an open reading frame of 1,185 bp which codes for 394 amino acids with a predicted molecular weight of 45 kDa. The activity of the gene product was confirmed via GCMS, which showed a functional putative Δ9-fatty acid desaturase capable of increasing the total amount of cellular unsaturated fatty acids of the E. coli cells expressing the gene. The results demonstrate that the cellular palmitoleic acids have increased two-fold upon expression at 15°C using only 0.1 mM IPTG. Therefore, PA3FAD9 from Pseudomonas sp.A3 codes for a Δ9-fatty acid desaturase-like protein which was actively expressed in E. coli. PMID:27494717

  15. Tales of diversity: Genomic and morphological characteristics of forty-six Arthrobacter phages.

    Directory of Open Access Journals (Sweden)

    Karen K Klyczek

    Full Text Available The vast bacteriophage population harbors an immense reservoir of genetic information. Almost 2000 phage genomes have been sequenced from phages infecting hosts in the phylum Actinobacteria, and analysis of these genomes reveals substantial diversity, pervasive mosaicism, and novel mechanisms for phage replication and lysogeny. Here, we describe the isolation and genomic characterization of 46 phages from environmental samples at various geographic locations in the U.S. infecting a single Arthrobacter sp. strain. These phages include representatives of all three virion morphologies, and Jasmine is the first sequenced podovirus of an actinobacterial host. The phages also span considerable sequence diversity, and can be grouped into 10 clusters according to their nucleotide diversity, and two singletons each with no close relatives. However, the clusters/singletons appear to be genomically well separated from each other, and relatively few genes are shared between clusters. Genome size varies from among the smallest of siphoviral phages (15,319 bp to over 70 kbp, and G+C contents range from 45-68%, compared to 63.4% for the host genome. Although temperate phages are common among other actinobacterial hosts, these Arthrobacter phages are primarily lytic, and only the singleton Galaxy is likely temperate.

  16. sp

    African Journals Online (AJOL)

    Vihar

    adopted as the first line drug. SP has few untoward effects if used carefully in therapeutic doses. Nausea, vomiting, generalized body weakness; diarrhea, skin rashes and hematological reactions are some of the associated side effects. The drug can cause severe skin reactions such as Steven Johnson's syndrome. This.

  17. Extracellular proteases from the Antarctic marine Pseudoalteromonas sp. P96-47 strain Proteasas extracelulares de la cepa marina antártica Pseudoalteromonas sp. P96-47

    Directory of Open Access Journals (Sweden)

    S.C. Vázquez

    2008-03-01

    Full Text Available The extracellular protease-production capacity of 33 bacterial isolates taken from marine biotopes in King George Island, Antarctica, was evaluated in liquid cultures. The P96-47 isolate was selected due to its high production capacity and was identified as Pseudoalteromonas sp. The optimal growth temperature was 20 °C and the optimal for protease production was 15 °C. Proteases were purified from culture supernatants, developing a multiple-band profile in zymograms. They were classified as neutral metalloproteases and worked optimally at 45 °C with an Eact of 47 kJ/ mol. Their stability was higher at neutral pH, retaining more than 80% of activity at pH 6-10 after 3 h incubation at 4 °C. After 90 min incubation at 40 and 50 °C, the percentages of residual activities were 78% and 44%. These results contribute to the basic knowledge of Antarctic marine proteases and also help evaluate the probable industrial applications of P96-47 proteases.La capacidad productora de proteasas extracelulares de 33 aislamientos bacterianos tomados de biotopos marinos en la Isla Rey Jorge, Antártida, fue evaluada en cultivo líquido. El aislamiento P96-47 fue seleccionado debido a su alta capacidad productora y fue identificado como Pseudoalteromonas sp. La temperatura óptima de crecimiento fue de 20 °C y la de producción de 15 °C. Las proteasas fueron purificadas a partir del sobrenadante de cultivo, y en los zimogramas desarrollaron un perfil de múltiples bandas. Estas proteasas fueron clasificadas como metaloproteasas neutras y se observó que trabajan óptimamente a 45 °C, con una Eact de 47 kJ/ mol. Su estabilidad fue superior a pH neutro y retuvieron más del 80% de su actividad a pH 6-10 después de 3 h de incubación a 4 °C. Luego de 90 min de incubación a 40 y 50 °C, las actividades residuales fueron 78% y 44%, respectivamente. Los resultados que se presentan en este trabajo contribuyen al conocimiento básico de las proteasas marinas ant

  18. Production of d-Tagatose from Dulcitol by Arthrobacter globiformis

    OpenAIRE

    Izumori, Ken; Miyoshi, Tatsuji; Tokuda, Sachiko; Yamabe, Keizo

    1984-01-01

    A process for the bacterial oxidation of dulcitol to d-tagatose has been developed. The strain Arthrobacter globiformis ST48 used in this fermentation was isolated from soil. The yield of d-tagatose accumulated in the medium from dulcitol was as high as 85%. About 14 g of d-tagatose crystals was isolated from 1 liter of 2% dulcitol medium.

  19. Beta-galactosidase from psychrotrophic microorganism (strain arthrobacter)

    Czech Academy of Sciences Publication Activity Database

    Hašek, Jindřich; Skálová, Tereza; Petroková, Hana; Vondráčková-Buchtelová, Eva; Dohnálek, Jan; Spiwok, V.; Lipovová, P.; Strnad, H.; Králová, B.

    2004-01-01

    Roč. 11, č. 1 (2004), s. 18-19 ISSN 1211-5894 R&D Projects: GA ČR GA204/02/0843 Institutional research plan: CEZ:AV0Z4050913 Keywords : . beta .-galactoside * cold active enzymes * Arthrobacter Subject RIV: EB - Genetics ; Molecular Biology

  20. Production of d-Tagatose from Dulcitol by Arthrobacter globiformis

    Science.gov (United States)

    Izumori, Ken; Miyoshi, Tatsuji; Tokuda, Sachiko; Yamabe, Keizo

    1984-01-01

    A process for the bacterial oxidation of dulcitol to d-tagatose has been developed. The strain Arthrobacter globiformis ST48 used in this fermentation was isolated from soil. The yield of d-tagatose accumulated in the medium from dulcitol was as high as 85%. About 14 g of d-tagatose crystals was isolated from 1 liter of 2% dulcitol medium. PMID:16346663

  1. Purification, characterisation and expression in Saccharomyces cerevisiae of LipG7 an enantioselective, cold-adapted lipase from the Antarctic filamentous fungus Geomyces sp. P7 with unusual thermostability characteristics.

    Science.gov (United States)

    Florczak, Tomasz; Daroch, Maurycy; Wilkinson, Mark Charles; Białkowska, Aneta; Bates, Andrew Derek; Turkiewicz, Marianna; Iwanejko, Lesley Ann

    2013-06-10

    A lipase, LipG7, has been purified from the Antarctic filamentous fungus Geomyces sp. P7 which was found to be cold-adapted and able to retain/regain its activity after heat denaturation. The LipG7 exhibits 100% residual activity following 1h incubation at 100°C whilst simultaneously showing kinetic adaptations to cold temperatures. LipG7 was also found to have industrial potential as an enantioselective biocatalyst as it is able to effectively catalyse the enantioselective transesterification of a secondary alcohol. The LipG7 coding sequence has been identified and cloned using 454 pyrosequencing of the transcriptome and inverse PCR. The LipG7 protein has been heterologously expressed in Saccharomyces cerevisiae BJ5465 and shown to exhibit the same characteristics as the native protein. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Molecular identification, morphological characterization and new insights into the ecology of larval Pseudoterranova cattani in fishes from the Argentine coast with its differentiation from the Antarctic species, P. decipiens sp. E (Nematoda: Anisakidae).

    Science.gov (United States)

    Timi, Juan T; Paoletti, Michela; Cimmaruta, Roberta; Lanfranchi, Ana L; Alarcos, Ana J; Garbin, Lucas; George-Nascimento, Mario; Rodríguez, Diego H; Giardino, Gisela V; Mattiucci, Simonetta

    2014-01-17

    Larvae of the genus Pseudoterranova constitute a risk for human health when ingested through raw or undercooked fish. They can provoke pseudoterranovosis in humans, a fish-borne zoonotic disease whose pathogenicity varies with the species involved, making their correct specific identification a necessary step in the knowledge of this zoonosis. Larvae of Pseudoterranova decipiens s.l. have been reported in several fish species from off the Argentine coasts; however, there are no studies dealing with their specific identification in this region. Here, a genetic identification and morphological characterization of larval Pseudoterranova spp. from three fish species sampled from Argentine waters and from Notothenia coriiceps from Antarctic waters was carried out. Larvae were sequenced for their genetic/molecular identification, including the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2), the first (ITS-1) and the second (ITS-2) internal transcribed spacers of the nuclear ribosomal DNA, and compared with all species of the P. decipiens (sensu lato) species complex (sequences available in GenBank). Further, adults of Pseudoterranova spp. from the definitive host, the southern sea lion, Otaria flavescens, from Argentine and Chilean coasts were sequenced at the same genes. The sequences obtained at the ITS-1 and ITS-2 genes from all the larvae examined from fish of Argentine waters, as well as the adult worms, matched 100% the sequences for the species P. cattani. The sequences obtained at mtDNA cox2 gene for Antarctic larvae matched 99% those available in GenBank for the sibling P. decipiens sp. E. Both MP and BI phylogenetic trees strongly supported P. cattani and P. decipiens sp. E as two distinct phylogenetic lineages and depicted the species P. decipiens sp. E as sister taxon to the remaining taxa of the P. decipiens complex. Larval morphometry was similar between specimens of P. cattani from Argentina, but significantly different from those of P

  3. Isolation of Arthrobacter species from the phyllosphere and demonstration of their epiphytic fitness

    NARCIS (Netherlands)

    Scheublin, T.R.; Leveau, J.H.J.

    2013-01-01

    Bacteria of the genus Arthrobacter are common inhabitants of the soil environment, but can also be recovered from leaf surfaces (the phyllosphere). Using enrichment cultures on 4-chlorophenol, we succeeded in specifically isolating Arthrobacter bacteria from ground cover vegetation in an apple

  4. Reclassification of Arthrobacter viscosus as Rhizobium viscosum comb. nov.

    Science.gov (United States)

    Flores-Félix, José David; Ramírez-Bahena, Martha Helena; Salazar, Sergio; Peix, Alvaro; Velázquez, Encarna

    2017-06-01

    The species Arthrobacter viscosus was isolated from soil from Guatemala and it was classified into the genus Arthrobacter on the basis of phenotypic traits. Nevertheless, the results of16S rRNA gene analysis indicated that this species is a member of the genus Rhizobium, with Rhizobium alamii GBV016T and Rhizobium mesosinicum CCBAU 25010T as the most closely related species with 99.64 and 99.48 % similarity, respectively. The similarity values for the recA gene are 92.2 and 94.4 % with respect to R. alamii GBV016T and R. mesosinicum CCBAU 25010T, respectively, and those for the atpD gene are 92.9 and 98.7 %, respectively. Results of DNA-DNA hybridization analysis yield averages of 46 and 41 % relatedness with respect to the type strains of R. alamii and R. mesosinicum, respectively. Phenotypic characteristics also differed from those of the most closely related species of the genus Rhizobium. Therefore, based on the data obtained in this study, we propose to classify strain LMG 16473T as representing a novel species named Rhizobiumviscosum comb. nov. (type strain LMG 16473T=CECT 908T).

  5. Antarctic science

    Science.gov (United States)

    Summerhayes, Colin

    Once upon a time, dinosaurs roamed Antarctica and swam in its seas. Since then, life evolved as the climate cooled into the ice ages. Life will no doubt continue to evolve there as the globe now warms. But nowadays, humans are having a profound and direct effect on life in Antarctica, the sub-Antarctic islands, and the surrounding Southern Ocean, which are being invaded by a wide range of alien species including microbes, algae, fungi, bryophytes, land plants, invertebrates, fish, birds, and mammals.

  6. Two Inducible Prophages of an Antarctic Pseudomonas sp. ANT_H14 Use the Same Capsid for Packaging Their Genomes – Characterization of a Novel Phage Helper-Satellite System

    Science.gov (United States)

    Dziewit, Lukasz; Radlinska, Monika

    2016-01-01

    Two novel prophages ФAH14a and ФAH14b of a psychrotolerant Antarctic bacterium Pseudomonas sp. ANT_H14 have been characterized. They were simultaneously induced with mitomycin C and packed into capsids of the same size and protein composition. The genome sequences of ФAH14a and ФAH14b have been determined. ФAH14b, the phage with a smaller genome (16,812 bp) seems to parasitize ФAH14a (55,060 bp) and utilizes its capsids, as only the latter encodes a complete set of structural proteins. Both viruses probably constitute a phage helper-satellite system, analogous to the P2-P4 duo. This study describes the architecture and function of the ФAH14a and ФAH14b genomes. Moreover, a functional analysis of a ФAH14a-encoded lytic enzyme and a DNA methyltransferase was performed. In silico analysis revealed the presence of the homologs of ФAH14a and ФAH14b in other Pseudomonas genomes, which may suggest that helper-satellite systems related to the one described in this work are common in pseudomonads. PMID:27387973

  7. Two Inducible Prophages of an Antarctic Pseudomonas sp. ANT_H14 Use the Same Capsid for Packaging Their Genomes - Characterization of a Novel Phage Helper-Satellite System.

    Directory of Open Access Journals (Sweden)

    Lukasz Dziewit

    Full Text Available Two novel prophages ФAH14a and ФAH14b of a psychrotolerant Antarctic bacterium Pseudomonas sp. ANT_H14 have been characterized. They were simultaneously induced with mitomycin C and packed into capsids of the same size and protein composition. The genome sequences of ФAH14a and ФAH14b have been determined. ФAH14b, the phage with a smaller genome (16,812 bp seems to parasitize ФAH14a (55,060 bp and utilizes its capsids, as only the latter encodes a complete set of structural proteins. Both viruses probably constitute a phage helper-satellite system, analogous to the P2-P4 duo. This study describes the architecture and function of the ФAH14a and ФAH14b genomes. Moreover, a functional analysis of a ФAH14a-encoded lytic enzyme and a DNA methyltransferase was performed. In silico analysis revealed the presence of the homologs of ФAH14a and ФAH14b in other Pseudomonas genomes, which may suggest that helper-satellite systems related to the one described in this work are common in pseudomonads.

  8. Genome sequence of Arthrobacter antarcticus strain W2, isolated from a slaughterhouse

    DEFF Research Database (Denmark)

    Herschend, Jakob; Raghupathi, Prem Krishnan; Røder, Henriette Lyng

    2016-01-01

    We report the draft genome sequence ofArthrobacter antarcticusstrain W2, which was isolated from a wall of a small slaughterhouse in Denmark. The 4.43-Mb genome sequence was assembled into 170 contigs.......We report the draft genome sequence ofArthrobacter antarcticusstrain W2, which was isolated from a wall of a small slaughterhouse in Denmark. The 4.43-Mb genome sequence was assembled into 170 contigs....

  9. Characterization of an exo-inulinase from Arthrobacter: a novel NaCl-tolerant exo-inulinase with high molecular mass.

    Science.gov (United States)

    Shen, Jidong; Zhang, Rui; Li, Junjun; Tang, Xianghua; Li, Ruixian; Wang, Min; Huang, Zunxi; Zhou, Junpei

    2015-01-01

    A glycoside hydrolase family 32 exo-inulinase gene was cloned from Arthrobacter sp. HJ7 isolated from saline soil located in Heijing town. The gene encodes an 892-residue polypeptide with a calculated mass of 95.1 kDa and a high total frequency of amino acid residues G, A, and V (30.0%). Escherichia coli BL21 (DE3) cells were used as hosts to express the exo-inulinase gene. The recombinant exo-inulinase (rInuAHJ7) showed an apparently maximal activity at pH 5.0-5.5 and 40-45°C. The addition of 1.0 and 10.0 mM Zn(2+) and Pb(2+) had little or no effect on the enzyme activity. rInuAHJ7 exhibited good salt tolerance, retaining more than 98% inulinase activity at a concentration of 3.0%-20.0% (w/v) NaCl. Fructose was the main product of inulin, levan, and Jerusalem artichoke tubers hydrolyzed by the enzyme. The present study is the first to report the identification and characterization of an Arthrobacter sp exo-inulinase showing a high molecular mass of 95.1 kDa and NaCl tolerance. These results suggest that the exo-inulinase might be an alternative material for potential applications in processing seafood and other foods with high saline contents, such as marine algae, pickles, and sauces.

  10. [New data on trematodes of Antarctic fish].

    Science.gov (United States)

    Sokolov, S G; Gordeev, I I

    2015-01-01

    Deepwater fishes from the Amundsen Sea, d'Urville Sea, Ross Sea, Cooperation Sea, Weddell Sea, and open waters of the South-West part of the Pacific sector of the Antarctic were examined. Fourteen species of trematodes were found. Muraenolepitrema magnatestis Gaevskaya et Rodjuk, 1988 and Helicometrina sp. were found in the Antarctic for the first time. Muraenolepitrema magnatestis was redescribed and basing on this, diagnosis of the genus Muraenolepitrema was amended. Muraenolepitrema magnatestis possesses the uroproct and glandular cells that are loosely arranged around the external seminal vesicle (without a membranous sac).

  11. Erythema caused by a localised skin infection with Arthrobacter mysorens

    Directory of Open Access Journals (Sweden)

    Chakraborty Trinad

    2010-12-01

    Full Text Available Abstract Background Skin erythemas of unknown origin are a frequent reason for consulting the general practitioner or dermatologist. Case presentation Here we report a case of an erythema resembling the erythema migrans manifestation of Lyme disease, but with atypical symptoms like persistent pruritus. The patient had no history of a recent tick-bite but displayed a positive serology for an advanced stage of Lyme borreliosis, which stood in contrast to the clinical manifestation of erythema migrans as a symptom of early Lyme disease. Three skin swabs and soil samples, collected in the area where the patient possibly acquired the infection, were examined by bacterial and fungal culture methods. Microorganisms were identified by using 16 S rRNA gene sequencing and bioinformatics. The patient and soil isolates were compared by employing RAPD analysis. The serum samples of the patient were examined by immunoblotting. Arthrobacter mysorens, a soil bacterium, was isolated from the collected skin and soil samples. The identity of both isolates was determined by molecular fingerprinting methods. A. mysorens was proven to be causative for the erythema by direct isolation from the affected skin and a positive serology, thus explaining the atypical appearance of the erythema compared to erythema migrans caused by Borrelia infection. Conclusions Infections with A.mysorens might be underreported and microbiological diagnostic techniques should be applied in cases of patients with unclear erythemas, resembling erythema migrans, without a history of tick bites.

  12. Erythema caused by a localised skin infection with Arthrobacter mysorens.

    Science.gov (United States)

    Imirzalioglu, Can; Hain, Torsten; Hossain, Hamid; Chakraborty, Trinad; Domann, Eugen

    2010-12-15

    Skin erythemas of unknown origin are a frequent reason for consulting the general practitioner or dermatologist. Here we report a case of an erythema resembling the erythema migrans manifestation of Lyme disease, but with atypical symptoms like persistent pruritus. The patient had no history of a recent tick-bite but displayed a positive serology for an advanced stage of Lyme borreliosis, which stood in contrast to the clinical manifestation of erythema migrans as a symptom of early Lyme disease. Three skin swabs and soil samples, collected in the area where the patient possibly acquired the infection, were examined by bacterial and fungal culture methods. Microorganisms were identified by using 16 S rRNA gene sequencing and bioinformatics. The patient and soil isolates were compared by employing RAPD analysis. The serum samples of the patient were examined by immunoblotting. Arthrobacter mysorens, a soil bacterium, was isolated from the collected skin and soil samples. The identity of both isolates was determined by molecular fingerprinting methods. A. mysorens was proven to be causative for the erythema by direct isolation from the affected skin and a positive serology, thus explaining the atypical appearance of the erythema compared to erythema migrans caused by Borrelia infection. Infections with A. mysorens might be underreported and microbiological diagnostic techniques should be applied in cases of patients with unclear erythemas, resembling erythema migrans, without a history of tick bites.

  13. Review of the taxonomy of the genus Arthrobacter, emendation of the genus Arthrobacter sensu lato, proposal to reclassify selected species of the genus Arthrobacter in the novel genera Glutamicibacter gen. nov., Paeniglutamicibacter gen. nov., Pseudoglutamicibacter gen. nov., Paenarthrobacter gen. nov. and Pseudarthrobacter gen. nov., and emended description of Arthrobacter roseus.

    Science.gov (United States)

    Busse, Hans-Jürgen

    2016-01-01

    In this paper, the taxonomy of the genus Arthrobacter is discussed, from its first description in 1947 to the present state. Emphasis is given to intrageneric phylogeny and chemotaxonomic characteristics, concentrating on quinone systems, peptidoglycan compositions and polar lipid profiles. Internal groups within the genus Arthrobacter indicated from homogeneous chemotaxonomic traits and corresponding to phylogenetic grouping and/or high 16S rRNA gene sequence similarities are highlighted. Furthermore, polar lipid profiles and quinone systems of selected species are shown, filling some gaps concerning these chemotaxonomic traits. Based on phylogenetic groupings, 16S rRNA gene sequence similarities and homogeneity in peptidoglycan types, quinone systems and polar lipid profiles, a description of the genus Arthrobacter sensu lato and an emended description of Arthrobacter roseus are provided. Furthermore, reclassifications of selected species of the genus Arthrobacter into novel genera are proposed, namely Glutamicibacter gen. nov. (nine species), Paeniglutamicibacter gen. nov. (six species), Pseudoglutamicibacter gen. nov. (two species), Paenarthrobacter gen. nov. (six species) and Pseudarthrobacter gen. nov. (ten species).

  14. CLONING AND CHARACTERIZATION OF THE PHTHALATE CATABOLISM REGION OF PRE1 OF ARTHROBACTER KEYSERI 12B

    Science.gov (United States)

    o-Phthalate (benzene-1,2-dicarboxylate) is a central intermediate in the bacterial degradation of phthalate ester plasticizers as well as of a number of fused-ring polycyclic aromatic hydrocarbons found in fossil fuels. In Arthrobacter keyseri 12B, the genes encoding catabolism o...

  15. Arthrobacter luteus restriction endonuclease cleavage map of X174 RF DNA

    NARCIS (Netherlands)

    Vereijken, J.M.; Mansfeld, A.D.M. van; Baas, P.D.; Jansz, H.S.

    1975-01-01

    Cleavage of X174 RF DNA with the restriction endonuclease from Arthrobacter luteus (Alu I) produces 23 fragments of approximately 24–1100 base pairs in length. The order of most of these fragments has been established by digestion of Haemophilus influenzae Rd (Hind II) and Haemophilus aegyptius (Hae

  16. Hexameric structure of cold active beta-galactosidase from Arthrobacter sp. C2-2

    Czech Academy of Sciences Publication Activity Database

    Skálová, Tereza; Dohnálek, Jan; Vondráčková, Eva; Petroková, Hana; Lipovová, P.; Spiwok, V.; Strnad, H.; Králová, B.; Hašek, Jindřich

    2005-01-01

    Roč. 12, č. 1 (2005), s. 4 ISSN 1211-5894. [Meeting of Structural Biologists /4./. 10.03.2005-12.03.2005, Nové Hrady] R&D Projects: GA ČR(CZ) GA204/02/0843 Institutional research plan: CEZ:AV0Z4050913 Keywords : x-ray diffraction * beta - galactosidase * cold active Subject RIV: CD - Macromolecular Chemistry

  17. Interactions between .beta.-galactosidase from Arthrobacter sp. C2-2 and its substrates

    Czech Academy of Sciences Publication Activity Database

    Štěpánková, Andrea; Skálová, Tereza; Dohnálek, Jan; Dušková, Jarmila; Kolenko, Petr; Hašek, Jindřich; Spiwok, V.; Lipovová, P.

    2008-01-01

    Roč. 15, 3a (2008), s. 38 ISSN 1211-5894. [FEBS Advanced Course - Advanced Methods in Macromolecular Crystallization /3./. 03.10.2008-10.10.2008, Nové Hrady] R&D Projects: GA ČR GA204/02/0843; GA ČR GA305/07/1073; GA AV ČR KJB500500512 Institutional research plan: CEZ:AV0Z40500505 Keywords : X-ray structure * active site * beta - galactosidase Subject RIV: CD - Macromolecular Chemistry

  18. Application of thermoalkalophilic xylanase from Arthrobacter sp. MTCC 5214 in biobleaching of kraft pulp

    Digital Repository Service at National Institute of Oceanography (India)

    Khandeparker, R.; Bhosle, N.B.

    released by enzyme treatment showed a characteristic peak at 280 nm indicating the presence of lignin in the released coloring matter. Enzymatic prebleaching of kraft pulp showed 20 % reduction in kappa number of the pulp without much change in viscosity...

  19. Antarctic Ice Velocity Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This compilation of recent ice velocity data of the Antarctic ice sheet is intended for use by the polar scientific community. The data are presented in tabular form...

  20. Flocculating performance of a bioflocculant produced by Arthrobacter humicola in sewage waste water treatment.

    Science.gov (United States)

    Agunbiade, Mayowa Oladele; Van Heerden, Esta; Pohl, Carolina H; Ashafa, Anofi Tom

    2017-06-12

    The discharge of poorly treated effluents into the environment has far reaching, consequential impacts on human and aquatic life forms. Thus, we evaluated the flocculating efficiency of our test bioflocculant and we report for the first time the ability of the biopolymeric flocculant produced by Arthrobacter humicola in the treatment of sewage wastewater. This strain was isolated from sediment soil sample at Sterkfontein dam in the Eastern Free State province of South Africa. Basic Local Alignment Search Tool (BLAST) analysis of the nucleotide sequence of the 16S rDNA revealed the bacteria to have 99% similarity to Arthrobacter humicola strain R1 and the sequence was deposited in the Gene bank as Arthrobacter humicola with accession number KC816574.1. Flocculating activity was enhanced with the aid of divalent cations, pH 12, at a dosage concentration of 0.8 mg/mL. The purified bioflocculant was heat stable and could retain more than 78% of its flocculating activity after heating at 100 °C for 25 min. Fourier Transform Infrared Spectroscopy analysis demonstrated the presence of hydroxyl and carboxyl moieties as the functional groups. The thermogravimetric analysis was used to monitor the pyrolysis profile of the purified bioflocculant and elemental composition revealed C: O: Na: P: K with 13.90: 41.96: 26.79: 16.61: 0.74 weight percentage respectively. The purified bioflocculant was able to remove chemical oxygen demand, biological oxygen demand, suspended solids, nitrate and turbidity from sewage waste water at efficiencies of 65.7%, 63.5%, 55.7%, 71.4% and 81.3% respectively. The results of this study indicate the possibility of using the bioflocculant produced by Arthrobacter humicola as a potential alternative to synthesized chemical flocculants in sewage waste water treatment and other industrial waste water.

  1. Temperature-dependent enthalpy of oxygenation in Antarctic fish hemoglobins

    DEFF Research Database (Denmark)

    Fago, A.; Wells, R.M.G.; Weber, Roy E.

    1997-01-01

    literature data for the enthalpy of oxygenation in Antarctic fish hemoglobins derives from the use of the nonintegrated (linearized) form of the van't Hoff equation over different temperature ranges. The general assumption that a low heat of oxygenation in hemoglobins from polar animals represents......The effect of temperature on the oxygen-binding properties of the hemoglobins of three cold-adapted Antarctic fish species, Dissostichus mawsoni, Pagothenia borchgrevinki and Trematomus, sp., has been investigated under different pH values and buffer conditions. A clear non linear van't Hoff plot...

  2. Regulation and function of transaldolase isoenzymes involved in sugar and one-carbon metabolism in the ribulose monophosphate cycle methylotroph Arthrobacter P1

    NARCIS (Netherlands)

    Levering, P.R.; Dijkhuizen, Lubbert

    In the facultative methylotroph Arthrobacter P1 the enzyme transaldolase plays an important role in both the pentose phosphate pathway and in the ribulose monophosphate cycle of formaldehyde fixation. Among gluconate-negative mutants of Arthrobacter P1 strains occurred which also were unable to grow

  3. Impact of phenolic substrate and growth temperature on the arthrobacter chlorophenolicus proteome

    Energy Technology Data Exchange (ETDEWEB)

    Unell, Maria; Abraham, Paul E.; Shah, Manesh; Zhang, Bing; Ruckert, Christian; VerBerkmoes, Nathan C.; Jansson, Janet K.

    2009-02-15

    We compared the Arthrobacter chlorophenolicus proteome during growth on 4-chlorophenol, 4-nitrophenol or phenol at 5 C and 28 C; both for the wild type and a mutant strain with mass spectrometry based proteomics. A label free workflow employing spectral counting identified 3749 proteins across all growth conditions, representing over 70% of the predicted genome and 739 of these proteins form the core proteome. Statistically significant differences were found in the proteomes of cells grown under different conditions including differentiation of hundreds of unknown proteins. The 4-chlorophenol-degradation pathway was confirmed, but not that for phenol.

  4. Imported anthropogenic bacteria may survive the Antarctic winter and introduce new genes into local bacterial communities

    OpenAIRE

    Brat Kristian; Sedlacek Ivo; Sevcikova Alena; Merta Zdenek; Laska Kamil; Sevcik Pavel

    2016-01-01

    We studied dynamic changes in anthropogenic bacterial communities at a summer-operated Czech research base (the Mendel Research Station) in the Antarctic during 2012 and 2013. We observed an increase in total numbers of detected bacteria between the beginning and the end of each stay in the Antarctic. In the first series of samples, bacteria of Bacillus sp. predominated. Surprisingly, high numbers of Gram-positive cocci and coliforms were found (including opportunistic human pathogens), altho...

  5. Accumulation of rare earth elements by siderophore-forming Arthrobacter luteolus isolated from rare earth environment of Chavara, India.

    Science.gov (United States)

    Emmanuel, E S Challaraj; Ananthi, T; Anandkumar, B; Maruthamuthu, S

    2012-03-01

    In this study, Arthrobacter luteolus, isolated from rare earth environment of Chavara (Quilon district, Kerala, India), were found to produce catechol-type siderophores. The bacterial strain accumulated rare earth elements such as samarium and scandium. The siderophores may play a role in the accumulation of rare earth elements. Catecholate siderophore and low-molecular-weight organic acids were found to be present in experiments with Arthrobacter luteolus. The influence of siderophore on the accumulation of rare earth elements by bacteria has been extensively discussed.

  6. Regional genetic diversity patterns in Antarctic hairgrass (Deschampsia antartica Desv.)

    NARCIS (Netherlands)

    van de Wouw, M.J.; Van Dijk, P.J.; Huiskes, A.H.L.

    2008-01-01

    Aim To determine patterns in diversity of a major Antarctic plant species, including relationships of Antarctic populations with those outside the Antarctic zone. Location Antarctic Peninsula, Maritime Antarctica, sub-Antarctic islands, Falkland Islands and South America. Methods Amplified fragment

  7. Degradation of (-)-ephedrine by Pseudomonas putida. Detection of (-)-ephedrine: NAD+-oxidoreductase from Arthrobacter globiformis.

    Science.gov (United States)

    Klamann, E; Lingens, F

    1980-01-01

    A bacterium utilizing the alkaloid (-)-ephedrine as its sole source of carbon was isolated by an enrichment-culture technique from soil supplemented with 4-benzoyl-1,3-oxazolidinon-(2). The bacterium was indentified as Pseudomonas putida by morphological and physiological studies. The following metabolites were isolated from the culture fluid: methylamine, formaldehyde, methylbenzoylcarbinol (2-hydroxy-1-oxo-1 phenylpropane), benzoid acid, pyrocatechol and cis, cis-muconic acid. A pathway for the degradation of (-)-ephedrine by Pseudomonas putida is proposed and compared with the degradative pathway in Arthrobacter globiformis. The enzyme, which is responsible for the first step in the catabolism of (-)-ephedrine could be demonstrated in extracts from Arthrobacter globiformis. This enzyme catalyses the dehydrogenation of (-)-ephedrine yielding phenylacetylcarbinol/methylbenzoylcarbinol and methylamine. It requires NAD+ as cofactor and exhibits optimal activity at pH 11 in 0.1 M glycine/NaOH buffer. The Km value for (-)-ephedrine is 0.02 mM and for NAD+ 0.11 mM, respectively. No remarkable loss of activity is observed following treatment with EDTA. The enzyme has been shown to react with a wide range of ethanolamines. A slight enrichment was obtained by ammonium sulphate precipitation. The name (-)-ephedrine: NAD+-oxidoreductase (deaminating) is proposed.

  8. IPAB Antarctic Drifting Buoy Data

    Data.gov (United States)

    National Aeronautics and Space Administration — The World Climate Research Programme (WCRP) International Programme for Antarctic Buoys (IPAB), through participating research organizations in various countries,...

  9. Modelling the Antarctic Ice Sheet

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Holm, A.

    2015-01-01

    Science) Antarctic Ice Sheet (DAIS) model (Shaffer 2014) is forced by reconstructed time series of Antarctic temperature, global sea level and ocean subsurface temperature over the last two glacial cycles. In this talk a modelling work of the Antarctic ice sheet over most of the Cenozoic era using...... the DAIS model will be presented. G. Shaffer (2014) Formulation, calibration and validation of the DAIS model (version 1), a simple Antarctic ice sheet model sensitive to variations of sea level and ocean subsurface temperature, Geosci. Model Dev., 7, 1803‐1818...

  10. Aglomerularism in Antarctic fish.

    Science.gov (United States)

    Dobbs, G H; Lin, Y; DeVries, A L

    1974-08-30

    Urine formation in antarctic bony fish does not involve glomerular filtration. Evidence for aglomerularism came from both direct observation of kidney serial sections by light microscopy and the low concentrations of inulin labeled with carbon-14 that were excreted into the urine when this renal clearance tracer was injected into the bloodstream via a cannula implanted in the caudal vein. Aglomerularism most likely prevents urinary loss of glycoproteins with biological antifreeze properties.

  11. Antarctic, Sub-Antarctic and cold temperate echinoid database

    Directory of Open Access Journals (Sweden)

    Benjamin Pierrat

    2012-06-01

    Full Text Available This database includes spatial data of Antarctic, Sub-Antarctic and cold temperate echinoid distribution (Echinodermata: Echinoidea collected during many oceanographic campaigns led in the Southern Hemisphere from 1872 to 2010. The dataset lists occurrence data of echinoid distribution south of 35°S latitude, together with information on taxonomy (from species to genus level, sampling sources (cruise ID, sampling dates, ship names and sampling sites (geographic coordinates and depth. Echinoid occurrence data were compiled from the Antarctic Echinoid Database (David et al., 2005a, which integrates records from oceanographic cruises led in the Southern Ocean until 2003. This database has been upgraded to take into account data from oceanographic cruises led after 2003. The dataset now reaches a total of 6160 occurrence data that have been checked for systematics reliability and consistency. It constitutes today the most complete database on Antarctic and Sub-Antarctic echinoids.

  12. [The plant growth-promoting rhizobacterium Arthrobacter agilis UMCV2 endophytically colonizes Medicago truncatula].

    Science.gov (United States)

    Aviles-Garcia, Maria Elizabeth; Flores-Cortez, Idolina; Hernández-Soberano, Christian; Santoyo, Gustavo; Valencia-Cantero, Eduardo

    Arthrobacter agilis UMCV2 is a rhizosphere bacterium that promotes legume growth by solubilization of iron, which is supplied to the plant. A second growth promotion mechanism produces volatile compounds that stimulate iron uptake activities. Additionally, A. agilis UMCV2 is capable of inhibiting the growth of phytopathogens. A combination of quantitative polymerase chain reaction and fluorescence in situ hybridization techniques were used here to detect and quantify the presence of the bacterium in the internal tissues of the legume Medicago truncatula. Our results demonstrate that A. agilis UMCV2 behaves as an endophytic bacterium of M. truncatula, particularly in environments where iron is available. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  13. Biosynthesis of NAD from nicotinic acid and nicotinamide by resting cells of Arthrobacter globiformis

    International Nuclear Information System (INIS)

    Kuwahara, Masaaki

    1978-01-01

    Isotopically labeled nicotinic acid and nicotinamide were incorporated into the metabolites of nicotinic acid-dependent pathway (Preiss-Handler pathway) of the NAD biosynthesis by resting cells of Arthrobacter globiformis. Azaserine and adenosine markedly stimulated the accumulation of NAD in the cells. Radioactive nicotinic acid and nicotinamide were also incorporated into an unknown compound when the cells were incubated in the presence of azaserine. Cell-free extract of the organism showed the NAD synthetase activity, which required ammonium ion and ATP for the amidation of deamido-NAD. Adenosine inhibited the enzyme activity. The organism possessed nicotinamidase, suggesting deamidation is the first step in the biosynthesis of NAD from nicotinamide. The activity was inhibited by NAD, NADP and NMN. (auth.)

  14. Purification and characterization of an NAD+-linked formaldehyde dehydrogenase from the facultative RuMP cycle methylotroph Arthrobacter P1

    NARCIS (Netherlands)

    Attwood, Margaret M.; Arfman, Nico; Weusthuis, Ruud A.; Dijkhuizen, Lubbert

    1992-01-01

    When Arthrobacter P1 is grown on choline, betaine, dimethylglycine or sarcosine, an NAD+-dependent formaldehyde dehydrogenase is induced. This formaldehyde dehydrogenase has been purified using ammonium sulphate fractionation, anion exchange- and hydrophobic interaction chromatography. The molecular

  15. Ecuadorian antarctic act

    International Nuclear Information System (INIS)

    1998-02-01

    To develop research in this continent involves to take communion with earth where the cold pole of the planet is located, the stormiest sea of the world surround it and where the capricious continental and geographical distribution permits the pass of meteorological violent and continuous systems. The Ecuador, in execution of the acquired commitments like Full Member of the System of the Antarctic Treaty, carried out the VII Expedition to the White Continent with an extensive program of scientific investigation in the field of: Sciences of Life, Sciences of the Earth and Atmospheric Sciences, so much in the environment of the Pacific Southeast, the Drake Pass, Bransfield Strait and the nearby ecosystems antarctic to Point Fort William in the Greenwich Island, site where the Ecuadorian station Pedro Vicente Maldonado is located. The scientific articles, result of the fruitful work of national investigator is consigned in this fourth edition. This publication constitutes our contribution to the world in the knowledge, understanding and handling of the marvelous White Continent from the middle of our planet, Ecuador

  16. Massalongia olechiana (Massalongiaceae, Peltigerales), a new lichen spcies from the Antarctic

    DEFF Research Database (Denmark)

    Alstrup, Vagn; Søchting, Ulrik

    2011-01-01

    A new species of lichenized ascomycete, Massalongia olechiana Alstrup et Søchting, sp. nov. (Massalongiaceae) is described from the South Shetland Islands and the Antarctic Peninsula. The species is distinguished by laminal isidia and 5-7-septate ascospores. The relationships with the other species...

  17. Contributions to Antarctic research II

    National Research Council Canada - National Science Library

    Elliot, David H

    1991-01-01

    Contents: The Antarctic research series: statement of objectives - Pedogenic linkages between the cold deserts of Antarctica and the polar deserts - Ablation rates of the ice fields in the vicinity of the Allan Hills, Victoria Land...

  18. Images of Antarctic Ice Shelves

    Data.gov (United States)

    National Aeronautics and Space Administration — Recent changes in the extent and stability of ice shelves in the Antarctic Peninsula prompted NSIDC to begin a monitoring program using data from the AVHRR Polar 1...

  19. Isolation, purification and characterization of xylanase produced by Arthrobacter sp. MTCC 5214 when grown in solid-state fermentation

    Digital Repository Service at National Institute of Oceanography (India)

    Khandeparker, R.; Bhosle, N.B.

    %) fractionation, and purified to homogeneity using size exclusion and ion exchange chromatography. The molecular mass of xylanase was approx. 20 kDa. Enzyme retained 100% activity at pH 7 and 8 for 24 h. It was interesting to note that at higher pH such as 9, 10...

  20. Crystal structure analysis of EstA from Arthrobacter sp. Rue61a--an insight into catalytic promiscuity.

    Science.gov (United States)

    Wagner, Ulrike Gabriella; DiMaio, Frank; Kolkenbrock, Stephan; Fetzner, Susanne

    2014-04-02

    In this article we analyze the reasons for catalytic promiscuity of a type VIII esterase with β-lactamase fold and the ability to cleave β-lactams. We compared the structure of this enzyme to those of an esterase of the same type without any lactamase ability, an esterase with moderate lactamase ability, and a class C β-lactamase with similar fold. Our results show that for these enzymes, the difference in the substrate specificity is sterically driven. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  1. Optimization of culturing conditions for isolated Arthrobacter sp. ZXY-2, an effective atrazine-degrading and salt-adaptive bacterium

    NARCIS (Netherlands)

    Zhao, X.; Wang, Li; Du, Linna; Yang, Jixian; Dong, Jing; Ma, Fang

    2017-01-01

    The increasing salinity in aquatic environments has had a negative impact on the biodegradation of atrazine, an extensively used herbicide which has been proven to pollute soil and water ecosystems. In the present study, a novel atrazine-degrading strain (ZXY-2) was isolated from industrial

  2. Environmental contamination in Antarctic ecosystems.

    Science.gov (United States)

    Bargagli, R

    2008-08-01

    Although the remote continent of Antarctica is perceived as the symbol of the last great wilderness, the human presence in the Southern Ocean and the continent began in the early 1900s for hunting, fishing and exploration, and many invasive plant and animal species have been deliberately introduced in several sub-Antarctic islands. Over the last 50 years, the development of research and tourism have locally affected terrestrial and marine coastal ecosystems through fuel combustion (for transportation and energy production), accidental oil spills, waste incineration and sewage. Although natural "barriers" such as oceanic and atmospheric circulation protect Antarctica from lower latitude water and air masses, available data on concentrations of metals, pesticides and other persistent pollutants in air, snow, mosses, lichens and marine organisms show that most persistent contaminants in the Antarctic environment are transported from other continents in the Southern Hemisphere. At present, levels of most contaminants in Antarctic organisms are lower than those in related species from other remote regions, except for the natural accumulation of Cd and Hg in several marine organisms and especially in albatrosses and petrels. The concentrations of organic pollutants in the eggs of an opportunistic top predator such as the south polar skua are close to those that may cause adverse health effects. Population growth and industrial development in several countries of the Southern Hemisphere are changing the global pattern of persistent anthropogenic contaminants and new classes of chemicals have already been detected in the Antarctic environment. Although the Protocol on Environmental Protection to the Antarctic Treaty provides strict guidelines for the protection of the Antarctic environment and establishes obligations for all human activity in the continent and the Southern Ocean, global warming, population growth and industrial development in countries of the Southern

  3. Characterization of a nitrilase from Arthrobacter aurescens CYC705 for synthesis of iminodiacetic acid.

    Science.gov (United States)

    Cai, Wenwen; Su, Erzheng; Zhu, Shujing; Ren, Yuhong; Wei, Dongzhi

    2014-01-01

    A nitrilase gene cyc705 from Arthrobacter aurescens CYC705 for synthesis of iminodiacetic acid (IDA) was cloned. This gene contained a 930 bp ORF, which encoded a polypeptide of 310 amino acids. A recombinant Escherichia coli BL21(DE3)/pET28a-cyc705 was constructed to achieve the heterologous expression of cyc705. This recombinant nitrilase was purified to homogeneity with a molecular weight of 36.7 kDa on SDS-PAGE and mass spectrometry, and characterized to be an oligomer of 14 subunits by gel permeation chromatography. Using iminodiacetonitrile (IDAN) as the substrate, the Vmax, Km, kcat and kcat/Km were 9.05 U mg(-1), 43.17 mM(-1), 94.1 min(-1) and 2.18×10(3) min(-1) M(-1), respectively. The optimum temperature and pH were 25°C and 5.8. The suitable substrates for the purified nitrilase were short-chain aliphatic dinitriles. High concentration of IDAN could be hydrolyzed to IDA in a shorter time.

  4. Indole-3-Acetic Acid Biosynthesis Pathways in the Plant-Beneficial Bacterium Arthrobacter pascens ZZ21.

    Science.gov (United States)

    Li, Mengsha; Guo, Rui; Yu, Fei; Chen, Xu; Zhao, Haiyan; Li, Huixin; Wu, Jun

    2018-02-01

    Arthrobacter pascens ZZ21 is a plant-beneficial, fluoranthene-degrading bacterial strain found in the rhizosphere. The production of the phytohormone indole-3-aectic acid (IAA) by ZZ21 is thought to contribute to its ability to promote plant growth and remediate fluoranthene-contaminated soil. Using genome-wide analysis combined with metabolomic and high-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses, we characterized the potential IAA biosynthesis pathways in A. pascens ZZ21. IAA production increased 4.5-fold in the presence of 200 mg·L -1 tryptophan in the culture medium. The transcript levels of prr and aldH , genes which were predicted to encode aldehyde dehydrogenases, were significantly upregulated in response to exogenous tryptophan. Additionally, metabolomic analysis identified the intermediates indole-3-acetamide (IAM), indole-3-pyruvic acid (IPyA), and the enzymatic reduction product of the latter, indole-3-lactic acid (ILA), among the metabolites of ZZ21, and subsequently also IAM, ILA, and indole-3-ethanol (TOL), which is the enzymatic reduction product of indole-3-acetaldehyde, by HPLC-MS. These results suggest that the tryptophan-dependent IAM and IPyA pathways function in ZZ21.

  5. Cyclic utilization of HP-β-CD in the bioconversion of cortisone acetate by Arthrobacter simplex.

    Science.gov (United States)

    Shen, Yanbing; Wang, Fang; Wang, Yanping; Zhao, Qing; Wang, Min

    2016-04-01

    To establish a method for the recovery and reutilization of hydroxypropyl-β-cyclodextrin (HP-β-CD) to lower the cost of its industrial application in cortisone acetate bioconversion. HP-β-CD is not degraded by Arthrobacter simplex CPCC140451 (ASP) resting cells and 96.4 % HP-β-CD could be recovered by isobutyl acetate extraction. Moreover, the inclusion ability of recovered HP-β-CD barely decreased. The saccharide metabolic and catalytic activities of ASP were greater in the aqueous phase after extracting with isobutyl acetate than other organic solvents. Cyclic utilization tests showed that cortisone acetate conversion ratio was 91.0 % after eight cycles and reached 95.7 % with 0.2-0.6 mM HP-β-CD. Furthermore, >90 % conversion ratio was reached per cycle through a co-cyclic-utilization method with HP-β-CD and immobilized ASP. Cortisone acetate conversion ratio in the HP-β-CD cyclic-utilization method is promising for industrial applications. The method can also be expanded to other CDs and other hydrophobic compounds bioconversion.

  6. Antarctic climate change and the environment

    Science.gov (United States)

    2009-11-01

    This volume provides a comprehensive, up-to-date account of how the physical and biological : environment of the Antarctic continent and Southern Ocean has changed from Deep Time until : the present day. It also considers how the Antarctic environmen...

  7. New Carcharhiniform Sharks (Chondrichthyes, Elasmobranchii) from the Early to Middle Eocene of Seymour Island, Antarctic Peninsula

    Science.gov (United States)

    Engelbrecht, Andrea; Mörs, Thomas; Reguero, Marcelo A.; Kriwet, Jürgen

    2018-01-01

    Seymour Island, Antarctic Peninsula, is known for its wealth of fossil remains. This island provides one of the richest fossiliferous Paleogene sequences in the world. Chondrichthyans seemingly dominate this Eocene marine fauna and offer a rare insight into high-latitude faunas during the Palaeogene. So far, only a few isolated teeth of carcharhinid sharks have been reported from Seymour Island. Bulk sampling in the well-exposed La Meseta and Submeseta formations yielded new and abundant chondrichthyan material, including numerous teeth of carcharhinid and triakid sharks. Here, we present a reevaluation of the previously described carcharhinid remains and a description of new taxa: Meridiogaleus cristatus, gen. et sp. nov., Kallodentis rythistemma, gen. et sp. nov., Abdounia richteri, sp. nov., and Abdounia mesetae, sp. nov. The carcharhiniforms Mustelus sp. and Galeorhinus sp. are reported based on rare material, whereas teeth previously assigned to Scoliodon represent a nomen dubium. PMID:29551850

  8. Antarctic radiation exposure doubles

    Science.gov (United States)

    Blue, Charles

    New data reveal that the Antarctic Peninsula received twice its normal maximum dose of hazardous solar ultraviolet radiation in December 1990. The prolonged persistence of the ozone hole over Antarctica caused an increased exposure of radiation, according to a paper published in the October issue of Geophysical Research Letters.John Frederick and Amy D. Alberts of the University of Chicago calculated the amount of ultraviolet solar spectral radiation from data collected at Palmer Station, Antarctica. During the spring of 1990 the largest observed values for ultraviolet radiation were approximately double the values expected, based on previous years. “The measurements from Palmer Station are consistent with similar data from McMurdo Sound, where a factor of three [ultraviolet radiation] enhancement was recorded, according to work by Knut Stamnes and colleagues at the University of Alaska,” Frederick said. “The radiation levels observed over Palmer Station in December 1990 may be the largest experienced in this region of the world since the development of the Earth's ozone layer,” he added.

  9. Regulating Antarctic Tourism and the Precautionary Principle

    NARCIS (Netherlands)

    Bastmeijer, C.J.; Roura, R.

    2004-01-01

    On the basis of an overview of the developments in Antarctic tourism since 1956, this current development note examines the issue of international regulation of Antarctic tourism. After discussing one of the main management issues in respect of Antarctic tourism ¿ the assessment and prevention of

  10. Diversity of proteolytic microbes isolated from Antarctic freshwater lakes and characteristics of their cold-active proteases

    Science.gov (United States)

    Matsui, Mihoko; Kawamata, Akinori; Kosugi, Makiko; Imura, Satoshi; Kurosawa, Norio

    2017-09-01

    Despite being an extreme environment, the water temperature of freshwater lakes in Antarctica reaches 10 °C in summer, accelerating biological activity. In these environments, proteolytic microbial decomposers may play a large role in protein hydrolysis. We isolated 71 microbial strains showing proteolytic activity at 4 °C from three Antarctic freshwater lakes. They were classified as bacteria (63 isolates) and eukaryotes (8 isolates). The bacterial isolates were classified into the genera Flavobacterium (28 isolates), Pseudomonas (14 isolates), Arthrobacter (10 isolates), Psychrobacter (7 isolates), Cryobacterium (2 isolates), Hymenobacter (1 isolate), and Polaromonas (1 isolate). Five isolates of Flavobacterium and one of Hymenobacter seemed to belong to novel species. All eukaryotic isolates belonged to Glaciozyma antarctica, a psychrophilic yeast species originally isolated from the Weddell Sea near the Joinville Island, Antarctica. A half of representative strains were psychrophilic and did not grow at temperatures above 25 °C. The protease secreted by Pseudomonas prosekii strain ANS4-1 showed the highest activity among all proteases from representative isolates. The results of inhibitor tests indicated that nearly all the isolates secreted metalloproteases. Proteases from four representative isolates retained more than 30% maximal activity at 0 °C. These results expand our knowledge about microbial protein degradation in Antarctic freshwater lakes.

  11. Antarctic analogs for Enceladus

    Science.gov (United States)

    Murray, A. E.; Andersen, D. T.; McKay, C. P.

    2014-12-01

    Enceladus is a new world for Astrobiology. The Cassini discovery of the icy plume emanating from the South Polar region indicates an active world, where detection of water, organics, sodium, and nano-particle silica in the plume strongly suggests that the source is a subsurface salty ocean reservoir. Recent gravity data from Cassini confirms the presence of a regional sea extending north to 50°S. An ocean habitat under a thick ice cover is perhaps a recurring theme in the Outer Solar System, but what makes Enceladus unique is that the plume jetting out into space is carrying samples of this ocean. Therefore, through the study of Enceladus' plumes we can gain new insights not only of a possible habitable world in the Solar Systems, but also about the formation and evolution of other icy-satellites. Cassini has been able to fly through this plume - effectively sampling the ocean. It is time to plan for future missions that do more detailed analyses, possibly return samples back to Earth and search for evidence of life. To help prepare for such missions, the need for earth-based analog environments is essential for logistical, methodological (life detection) and theoretical development. We have undertaken studies of two terrestrial environments that are close analogs to Enceladus' ocean: Lake Vida and Lake Untersee - two ice-sealed Antarctic lakes that represent physical, chemical and possibly biological analogs for Enceladus. By studying the diverse biology and physical and chemical constraints to life in these two unique lakes we will begin to understand the potential habitability of Enceladus and other icy moons, including possible sources of nutrients and energy, which together with liquid water are the key ingredients for life. Analog research such as this will also enable us to develop and test new strategies to search for evidence of life on Enceladus.

  12. Heterologous expression and characterization of choline oxidase from the soil bacterium Arthrobacter nicotianae.

    Science.gov (United States)

    Ribitsch, D; Karl, W; Wehrschütz-Sigl, E; Tutz, S; Remler, P; Weber, H J; Gruber, K; Stehr, R; Bessler, C; Hoven, N; Sauter, K; Maurer, K H; Schwab, H

    2009-01-01

    In the course of a microbial screening of soil samples for new oxidases, different enrichment strategies were carried out. With choline as the only carbon source, a microorganism was isolated and identified as Arthrobacter nicotianae. From this strain, a gene coding for a choline oxidase was isolated from chromosomal DNA. This gene named codA was cloned in Escherichia coli BL21-Gold and the protein (An_CodA) heterologously overexpressed as a soluble intracellular protein of 59.1 kDa. Basic biochemical characterization of purified protein revealed a pH optimum of 7.4 and activity over a broad temperature range (15-70 degrees C). Specific activities were determined toward choline chloride (4.70 +/- 0.12 U/mg) and the synthetic analogs bis(2-hydroxyethyl)-dimethylammonium chloride (0.05 +/- 0.45 x 10(-2) U/mg) and tris-(2-hydroxyethyl)-methylammonium methylsulfate (0.01 +/- 0.12 x 10(-2) U/mg). With increasing number of oxidizable groups, a significant decrease in activity was noted. Determination of kinetic parameters in atmorspheric oxygen resulted in K (M) = 1.51 +/- 0.09 mM and V (max) = 42.73 +/- 0.42 mU/min for choline chloride and K (M) = 4.77 +/- 0.76 mM and V (max) = 48.40 +/- 2.88 mU/min for the reaction intermediate betaine aldehyde respectively. Nuclear magnetic resonance spectroscopic analysis of the products formed during the enzyme reaction with choline chloride showed that in vitro the intermediate betaine aldehyde exists also free in solution.

  13. NAA for studying detoxification of Cr and Hg by Arthrobacter globiformis 151B

    International Nuclear Information System (INIS)

    Tsibakhashvili, N.; Mosulishvili, L.; Kirkesali, E.; Murusidze, I.; Frontasyeva, M.V.; Pavlov, S.S.; Zinicovscaia, I.I.

    2010-01-01

    Instrumental neutron activation analysis was used to study accumulation of Hg(II) and Cr(VI) ions in Arthrobacter globiformis 151B, a gram-positive, Cr(VI)-reducer aerobic bacterium isolated from basalt sample taken from the most polluted region in the Republic of Georgia (Kazreti). Experiments were focused on (1) accumulation of Hg(II) in bacterial cells; (2) accumulation of Cr(VI) in A. globiformis 151B in the presence of Hg(II) and (3) effects of Hg(II) and mixture of Cr(VI)-Hg(II) on the elemental composition of bacteria. It was shown that this bacterial strain possesses uptake mechanisms by which mercury toxicity can be reduced in environment and that accumulation of Cr(VI) in A. globiformis 151B is much higher in the presence of Hg(II) ions. Accumulation of Hg(II), similar to the Cr(VI) accumulation, follows well the Lengmuir-Freundlich model. NAA measurements showed increased content of Fe in bacteria under Hg and Cr action, suggesting that Fe-containing biomolecules play a decisive role in detoxifying of heavy metals by A. globiformis 151B. A concentration of 5000 μg/L of Hg(II) was found to be critical for A. globiformis 151B. At this concentration of Hg(II) the concentrations of both essential (Na, Mg, Al, Cl, K, Mn, Zn) and some non-essential elements (Rb, Sb, Sc, As) changed drastically along with a decrease of the biomass of bacteria by a factor of two. One may assume that under this high exposure to Hg(II) the structure of the bacterial cell wall was destroyed. (author)

  14. Enhancing arsenic removal from arsenic-contaminated water by Echinodorus cordifolius-endophytic Arthrobacter creatinolyticus interactions.

    Science.gov (United States)

    Prum, Channratha; Dolphen, Rujira; Thiravetyan, Paitip

    2018-05-01

    In this study, Echinodorus cordifolius was the best plant for arsenic removal compared to Cyperus alternifolius, Acrostichum aureum and Colocasia esculenta. Under arsenic stress, the combination of E. cordifolius with microbes (Bacillus subtilis and Arthrobacter creatinolyticus) was investigated. It was found that A. creatinolyticus, a native microbe, can endure arsenic toxicity, produce higher indole-3 acetic acid (IAA) and ammonium production better than B. subtilis. Interestingly, E. cordifolius-endophytic A. creatinolyticus interactions showed that dipping plant roots in A. creatinolyticus suspension for 5 min had the highest arsenic removal efficiency compared to dipping plant roots in A. creatinolyticus suspension for 2 h and inoculating A. creatinolyticus with E. cordifolius directly. Our findings indicated that under this inoculation condition, the inoculum could colonize from the roots to the shoots of the host tissues in order to avoid arsenic toxicity and favored arsenic removal by the host through plant growth-promoting traits, such as IAA production. Highest levels of IAA were found in plant tissues and the plants exhibited higher root elongation than other conditions. Moreover, low level of reactive oxygen species (ROS) was related to low arsenic stress. In addition, dipping E. cordifolius roots in A. creatinolyticus for 5 min was applied in a constructed wetland, the result showed higher arsenic removal than conventional method. Therefore, this knowledge can be applied at a real site for improving plant tolerance stress, plant growth stimulation, and enhancing arsenic remediation. Copyright © 2018 Elsevier Ltd. All rights reserved.

  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)

    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.

  16. Antarctic snow and global climate

    International Nuclear Information System (INIS)

    Granberg, H.B.

    2001-01-01

    Global circulation models (GCM) indicate that global warming will be most pronounced at polar regions and high latitudes, causing concern about the stability of the Antarctic ice cap. A project entitled the Seasonal Snow in Antarctica examined the properties of the near surface snow to determine the current conditions that influence snow cover development. The goal was to assess the response of the snow cover in Queen Maud Land (QML) to an increased atmospheric carbon dioxide content. The Antarctic snow cover in QML was examined as part of the FINNARP expeditions in 1999 and 2000 which examined the processes that influence the snow cover. Its energy and mass balance were also assessed by examining the near surface snow strata in shallow (1-2 m) pits and by taking measurements of environmental variables. This made it possible to determine if the glacier is in danger of melting at this northerly location in the Antarctic. The study also made it possible to determine which variables need to change and by how much, for significant melting to occur. It was shown that the Antarctic anticyclone creates particular conditions that protect the snow cover from melting. The anticyclone brings dry air from the stratosphere during most of the year and is exempt from the water vapour feedback. It was concluded that even a doubling of atmospheric carbon dioxide will not produce major snow melt runoff. 8 refs

  17. Antarctic grounding-line migration

    Science.gov (United States)

    Slater, T.; Konrad, H.; Shepherd, A.; Gilbert, L.; Hogg, A.; McMillan, M.; Muir, A. S.

    2017-12-01

    Knowledge of grounding-line position is critical for quantifying ice discharge into the ocean, as a boundary condition for numerical models of ice flow, and as an indicator of ice sheet stability. Although geological investigations have documented extensive grounding-line retreat since the period of the Last Glacial Maximum, observations of grounding line migration during the satellite era are restricted to a handful of locations. We combine satellite altimeter observations of ice-elevation change and airborne measurements of ice geometry to track movement of the Antarctic Ice Sheet grounding line. Based on these data, we estimate that 22%, 3%, and 10% of the West Antarctic, East Antarctic, and Antarctic Peninsula ice sheet grounding lines are retreating at rates faster than the typical pace since the Last Glacial Maximum, and that the continent loses over 200 km2 of grounded-ice area per year. Although by far the fastest rates of retreat occurred in the Amundsen Sea Sector, the Pine Island Glacier grounding line has stabilized - likely as a consequence of abated ocean forcing during the survey period.

  18. Taxon-specific differences in photoacclimation to fluctuating irradiance in an Antarctic diatom and a green flagellate

    NARCIS (Netherlands)

    van Leeuwe, M.A.; van Sikkelerus, B.; Gieskes, W.W C; Stefels, J.

    2005-01-01

    Photoacclimation towards rapid changes in irradiance was studied in 2 Antarctic microalgae, the diatom Chaetoceros brevis (Bacillariophyceae) and the flagellate Pyramimonas sp. (Prasinophyceae). Both species were subjected to 3 different light regimes. Two regimes of vertical mixing (1:1 h and 3:3 h

  19. Optimization of four types of antimicrobial agents to increase the inhibitory ability of marine Arthrobacter oxydans KQ11 dextranase mouthwash

    Science.gov (United States)

    Ren, Wei; Wang, Shujun; Lü, Mingsheng; Wang, Xiaobei; Fang, Yaowei; Jiao, Yuliang; Hu, Jianen

    2016-03-01

    We adopted the response surface methodology using single factor and orthogonal experiments to optimize four types of antimicrobial agents that could inhibit biofilm formation by Streptococcus mutans, which is commonly found in the human oral cavity and causes tooth decay. The objective was to improve the function of marine Arthrobacter oxydans KQ11 dextranase mouthwash (designed and developed by our laboratory). The experiment was conducted in a three-level, four-variable central composite design to determine the best combination of ZnSO4, lysozyme, citric acid and chitosan. The optimized antibacterial agents were 2.16 g/L ZnSO4, 14 g/L lysozyme, 4.5 g/L citric acid and 5 g/L chitosan. The biofilm formation inhibition reached 84.49%. In addition, microscopic observation of the biofilm was performed using scanning electron microscopy and confocal laser scanning microscopy. The optimized formula was tested in marine dextranase Arthrobacter oxydans KQ11 mouthwash and enhanced the inhibition of S. mutans. This work may be promoted for the design and development of future marine dextranase oral care products.

  20. Purification and characterization of d-allulose 3-epimerase derived from Arthrobacter globiformis M30, a GRAS microorganism.

    Science.gov (United States)

    Yoshihara, Akihide; Kozakai, Taro; Shintani, Tomoya; Matsutani, Ryo; Ohtani, Kouhei; Iida, Tetsuo; Akimitsu, Kazuya; Izumori, Ken; Gullapalli, Pushpa Kiran

    2017-02-01

    An enzyme that catalyzes C-3 epimerization between d-fructose and d-allulose was found in Arthrobacter globiformis strain M30. Arthrobacter species have long been used in the food industry and are well-known for their high degree of safety. The enzyme was purified by ion exchange and hydrophobic interaction chromatographies and characterized as a d-allulose 3-epimerase (d-AE). The molecular weight of the purified enzyme was estimated to be 128 kDa with four identical subunits. The enzyme showed maximal activity and thermostability in the presence of Mg 2+ . The optimal pH and temperature for enzymatic activity were 7.0-8.0 and 70°C, respectively. The enzyme was immobilized to ion exchange resin whereupon it was stable for longer periods than the free enzyme when stored at below 10°C. In the column reaction, the enzyme activity also maintained stability for more than 4 months. Under these conditions, 215 kg of d-allulose produced per liter immobilized enzyme, and this was the highest production yield of d-allulose reported so far. These highly stable properties suggest that this enzyme represents an ideal candidate for the industrial production of d-allulose. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  1. The response of soil Arthrobacter agilis lush13 to changing conditions: Transition between vegetative and dormant state.

    Science.gov (United States)

    Solyanikova, Inna P; Suzina, Nataliya E; Egozarian, Nataliya S; Polivtseva, Valentina N; Prisyazhnaya, Nataliya V; El-Registan, Galina I; Mulyukin, Andrey L; Golovleva, Ludmila A

    2017-10-03

    This work was aimed at studying the response of soil non-spore-forming actinobacterial strain Arthrobacter agilis Lush 13 to changing natural conditions, such as nutrient availability and the presence of degradable and recalcitrant aliphatic and aromatic substrates. The A. agilis strain Lush13 was able to degrade octane, nonane, hexadecane, benzoate, phenol, and 2,3-, 2,4-, 2,5-, 2,6-dichlorophenols, but not grew on 3,4-dichlorophenol, 2,3,4-, 2,4,5-, 2,4,6-trichlorophenol (TCP), pentachlorophenol (PCP), 2-chlorobenzoate, 3-chlorobenzoate, 3,5-dichlorobenzoate, 2,4-dichlorobenzoate. Under growth-arresting conditions due to nitrogen- or multiple starvation or recalcitrant (non-utilizable) carbon source, the studied strain preserved viability for prolonged periods (4-24 months) due to transition to dormancy in the form of conglomerated small and ultrasmall cyst-like dormant cells (CLC). Dormant cells were shown to germinate rapidly (30 min or later) after removal of starvation stress, and this process was followed by breakdown of conglomerates with the eliberation and further division of small multiple actively growing daughter cells. Results of this study shed some light to adaptive capabilities of soil arthrobacters in pure and polluted environments.

  2. [Catalytical properties of Arthrobacter nicotianae cells, a producer of glucose isomerase, immobilized in xerogel of silicium dioxide].

    Science.gov (United States)

    Perminova, L V; Kovalenko, G A; Rudina, N A; Sapunova, L I; Tamkovich, I O; Lobanok, A G

    2009-01-01

    Arthrobacter nicotinanae cells, producers of glucose isomerase, were immobilized in xerogel of silicium dioxide, and properties of the resulted heterogeneous biocatalysts were investigated in the process of isomerization of monosaccharide (glucose and fructose). The glucose isomerase activity of the resulted biocatalysts was shown to be 10 U/g, on average, taking into account the loss of the activity upon the immobilization, which amounted to 50% of the cell activity in suspension. The rate of the fructose isomerization increased linearly in the range of 55-80 degrees C with the temperature coefficient 1.3. The biocatalysts were stable in this range; they were rapidly inactivated, however, at increasing temperature. The half-inactivation time was six to seven h and five min or less at 80 degrees C and 85 degrees C, respectively. The half-inactivation time of heterogeneous biocatalysts was 50-90 h in the periodic process of isomerization of 2 M monosaccharides at 60 degrees C in the presence of the immobilized Arthrobacter nicotinanae cells.

  3. Comparative proteomic analysis of Arthrobacter phenanthrenivorans Sphe3 on phenanthrene, phthalate and glucose.

    Science.gov (United States)

    Vandera, Elpiniki; Samiotaki, Martina; Parapouli, Maria; Panayotou, George; Koukkou, Anna Irini

    2015-01-15

    In the present study, by applying comparative quantitative proteomics, we investigated the metabolic adaptation of Arthrobacter phenanthrenivorans Sphe3 when using phenanthrene, phthalate, glucose or glucose plus phenanthrene as sole carbon and energy sources. More than a third of the total Sphe3 proteins, with function prediction within the genome, were identified with confidence. Proteomic analysis data and annotated genomic information coincide, allowing us to clarify the phenanthrene catabolic pathway. We confirmed the implication of several proteins in aromatic substrate degradation by identifying those mediating the initial ring-hydroxylation and ring cleavage of phenanthrene to phthalate, phthalate degradation, as well as ortho- and meta-protocatechuate catabolism. Repression of catabolic genes by glucose was observed by both proteomic and transcriptional analyses. The presence of aromatic substrates resulted in changes in the abundance of proteins involved in substrate and amino acid metabolism, stress response, detoxification and membrane and cell wall metabolism. Uptake and transport associated proteins differ in the substrates used, indicating the use of different uptake mechanisms for transport of each compound in the Sphe3 cells. Our results also suggest the activation of a glyoxylate shunt in the presence of aromatic compounds, based on the up-regulation of the key enzymes of this pathway. A. phenanthrenivorans Sphe3, isolated from a creosote contaminated soil in Greece, can grow on phenanthrene as the sole source of carbon and energy. To explore the phenanthrene catabolic pathway by determining the key proteins involved in this pathway, as well as the global changes in proteins due to the adaptive response of Sphe3 cells grown on different substrates, we applied a gel-free quantitative proteomic analysis using nanoLC-MS/MS. To our knowledge this is the first study of comparative global proteomic changes occurring in the Sphe3 cells under exposure in

  4. Regulation of methylamine and formaldehyde metabolism in Arthrobacter P1. Formaldehyde is the inducing signal for the synthesis of the RuMP cycle enzyme hexulose phosphate synthase

    NARCIS (Netherlands)

    Croes, L.M.; Dijkhuizen, L.

    The inducing potential of formaldehyde on the synthesis of hexulose phosphate synthase, a key enzyme of the RuMP cycle in Arthrobacter P1, was investigated in resting cell suspensions. Induction of this enzyme only occurred at formaldehyde concentrations of 0.5 mM and below. No evidence was obtained

  5. Regulation of methylamine and formaldehyde metabolism in Arthrobacter P1. Effect of pulse-wise addition of "heterotrophic" substrates to C1 substrate-limited continuous cultures

    NARCIS (Netherlands)

    Croes, L.M.; Tiesma, L.; Dijkhuizen, L.

    1986-01-01

    The regulation of methylamine and formaldehyde metabolism in Arthrobacter P1 was investigated in carbon-limited continuous cultures. To avoid toxic effects of higher formaldehyde concentrations, formaldehyde-limited cultures were established in smooth substrate transitions from choline-limitation.

  6. Synthesis and oxidation by xanthine oxidase from arthrobacter M-4 of 6-aryl-4(3H)-pteridinones and related compounds

    NARCIS (Netherlands)

    Meester, De J.W.G.

    1987-01-01

    In this thesis xanthine oxidase from Arthrobacter M-4 in the form of a cell-free extract or as immobilized cells has been studied with regard to its application In preparative organic chemistry. The enzyme has a broad substrate specificity towards azaheterocycles as

  7. FjordPhyto: Antarctic Citizen Science Project

    OpenAIRE

    Lee Cusick, Allison

    2017-01-01

    The FjordPhyto Citizen Science project is designed to engage the International Association of Antarctic Tour Operators and their Guests in hands-on science as they journey along the fjords of the west Antarctic Peninsula. The Antarctic Peninsula is one of the fastest warming regions in the world. Melting glaciers bring an influx of freshwater and nutrients into the fjords potentially altering the biology at the phytoplankton level. Phytoplankton play a critical role in regulating the atmosphe...

  8. Fotoprotección antioxidante no-enzimática contra el potencial daño inducido por UVBR en una diatomea antártica (Thalassiosira sp. Non-enzymatic antioxidant photoprotection against potential UVBR-induced damage in an Antarctic diatom (Thalassiosira sp.

    Directory of Open Access Journals (Sweden)

    Marcelo Hernando

    2011-11-01

    Full Text Available In January 1999, unialgal cultures of the diatom Thalassiosira sp., solate from natural phyto-plankton assemblages from Potter Cove, Antarctica, were exposed to solar ultraviolet radiation (UVR, 280400 nm in order to study the long-term acclimation of this species. Ultraviolet radiation B (UVBR, 280-315 nm inhibited the growth rate during the first and second days of exposure. No UVBR inhibition was observed on the third day. The initial content of α-tocopherol (13 pmol (10(4 cell-1 showed a marked decrease during the exponential growth phase (4 pmol (10(4 cell-1 by day 3. The initial content of β-carotene (3 pmol (10(4 cell-1 did not show significant differences over time in cells exposed to UVBR. Two mycosporine-like amino acids (MAAs were identified: porphyra-334 and shinorine. Cellular concentrations of MAAs increased significantly on days 2 and 3, and exposure of the algae to UVBR significantly enhanced this value. The relative importance of MAAs concentration was significant (P Durante enero 1999, cultivos unialgales de una diatomea Thalassiosira sp., aislada de poblaciones fitoplanctónicas naturales de Caleta Carlos Potter, Antártida, fueron expuestos a radiación solar ultravioleta (UVR, 280-400 nm con el objetivo de estudiar su aclimatación a largo plazo. La radiación ultravioleta B (UVBR, 280-315 nm inhibió la tasa de crecimiento durante el primer y segundo día de exposición. No se observó inhibición por UVBR durante el tercer día. El contenido inicial de α-tocopherol (13 pmol (10(4 cel-1 mostró una marcada disminución durante la fase de crecimiento exponencial (4 pmol (10(4 cel-1 al día 3. El contenido inicial de β-caroteno (3 pmol (10(4 cel-1 no mostró diferencias significativas entre días en células expuestas a UVBR. Se identificaron dos aminoácidos parecidos a micosporina (MAAs, porfira-334 y shinorina. Las concentraciones celulares de MAAs mostraron aumentos significativos en los días 2 y 3, que resultaron

  9. ‘New’ Antarctic volcanos

    Science.gov (United States)

    Two previously unknown volcanos that show evidence o f recent eruptions were discovered in March on the east side of the Antarctic Peninsula, according to the National Science Foundation. The discovery brings to five the number of known active volcanos on the continent.Volcanic debris still covers a large swath of the adjacent Larsen Ice Shelf, pointing to very recent activity. In addition, one of the volcanos was steaming when the discovery was made, reports Oscar Gonzalez-Ferran of the University of Chile at Santiago. He made the discovery while doing a geophysical survey by helicopter of the Antarctic Peninsula. The two volcanos constitute the southernmost extension of the eastern side of the ‘ring of fire,’ a ring of volcanos that is believed to mark the active subduction zone on the periphery of the Pacific Ocean.

  10. AGU honored for Antarctic book

    Science.gov (United States)

    AGU has won an honorable mention award at the Fifteenth Annual Awards Program for Excellence in Professional and Scholarly Publishing sponsored by the Association of American Publishers for the book Volcanoes of the Antarctic Plate and Southern Oceans. The book is part of AGU's Antarctic Research Series, an outgrowth of research done during the International Geophysical Year that was begun in 1963 with a grant from the National Science Foundation. The award was presented at the AAP Annual Awards Dinner on February 6 at the Ritz-Carlton Hotel in Washington, D.C. The award consists of a medallion and a plate on which the names of the publisher, title, and authors are engraved.

  11. IPAB Antarctic Drifting Buoy Data, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The World Climate Research Programme (WCRP) International Programme for Antarctic Buoys (IPAB), through participating research organizations in various countries,...

  12. Heavy metals in Antarctic organisms

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, J.E.A. de; Moreno, V.J. [Universidad Nacional de Mar del Plata (Argentina); Gerpe, M.S.; Vodopivez, C. [Instituto Antartico Argentino, Buenos Aires (Argentina)

    1997-02-01

    To evaluate levels of essential (zinc and copper) and non-essential (mercury and cadmium) heavy metals, 34 species of organisms from different areas close to the Antarctic Peninsula were analysed. These included algae, filter-feeders, omnivorous invertebrates and vertebrates. Mercury was not detected, while cadmium was found in the majority of organisms analysed (detection limit was 0.05 ppm for both metals). The highest cadmium concentration was observed in the starfish Odontaster validus. Anthozoans, sipunculids and nudibranchs showed maximum levels of zinc, while the highest copper level was found in the gastropod Trophon brevispira. Mercury and cadmium levels in fishes were below the detection limit. Concentrations of essential and non-essential metals in birds were highest in liver followed by muscle and eggs. Cadmium and mercury levels in muscle of southern elephant seals were above the detection limit, whereas in Antarctic fur seals they were below it. The objective of the study was to gather baseline information for metals in Antarctic Ocean biota that may be needed to detect, measure and monitor future environmental changes. 46 refs., 7 figs., 8 tabs.

  13. Antarctic skuas recognize individual humans.

    Science.gov (United States)

    Lee, Won Young; Han, Yeong-Deok; Lee, Sang-Im; Jablonski, Piotr G; Jung, Jin-Woo; Kim, Jeong-Hoon

    2016-07-01

    Recent findings report that wild animals can recognize individual humans. To explain how the animals distinguish humans, two hypotheses are proposed. The high cognitive abilities hypothesis implies that pre-existing high intelligence enabled animals to acquire such abilities. The pre-exposure to stimuli hypothesis suggests that frequent encounters with humans promote the acquisition of discriminatory abilities in these species. Here, we examine individual human recognition abilities in a wild Antarctic species, the brown skua (Stercorarius antarcticus), which lives away from typical human settlements and was only recently exposed to humans due to activities at Antarctic stations. We found that, as nest visits were repeated, the skua parents responded at further distances and were more likely to attack the nest intruder. Also, we demonstrated that seven out of seven breeding pairs of skuas selectively responded to a human nest intruder with aggression and ignored a neutral human who had not previously approached the nest. The results indicate that Antarctic skuas, a species that typically inhabited in human-free areas, are able to recognize individual humans who disturbed their nests. Our findings generally support the high cognitive abilities hypothesis, but this ability can be acquired during a relatively short period in the life of an individual as a result of interactions between individual birds and humans.

  14. [Glucose isomerase activity in suspension of Arthrobacter nicotianae cells and adsorption immobilization of the microorganisms on inorganic carriers].

    Science.gov (United States)

    Kovalenko, G A; Perminova, L V; Terent'eva, T G; Sapunova, L I; Lobanok, A G; Chuenko, T V; Rudina, N A; Cherniak, E I

    2008-01-01

    Kinetics of monosaccharide isomerization has been studied in suspensions of intact, non-growing Arthrobacter nicotianae cells. Under the conditions of the study, glucose and fructose were isomerized at the same maximum rate of 700 micromol/min per 1 g dried cells, which increased with temperature (the dependence was linear at 60-80 degrees C). The proposed means of adsorption immobilization of A. nicotianae cells involve inorganic carriers differing in macrostructure, chemical nature, and surface characteristics. Biocatalysts obtained by adsorbing the cells of A. nicotianae on carbon-containing foam ceramics in the coarse of submerged cultivation were relatively stable and retained original activity (catalysis of monosaccharide isomerization) throughout 14 h of use at 70 degrees C. Maximum glucose isomerase activity (2 micromol/min per 1 g) was observed with biocatalysts prepared by adsorption of non-growing A. nicotianae cells to the macroporous carbon-mineral carrier Sapropel and subsequent drying of the cell suspension together with the carrier.

  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)

    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.

  16. 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).

  17. [Bacterium Arthrobacter agilis UMCV2 and diverse amines inhibit in vitro growth of wood-decay fungi].

    Science.gov (United States)

    Orozco-Mosqueda, M Del Carmen; Valencia-Cantero, Eduardo; López-Albarrán, Pablo; Martínez-Pacheco, Mauro; Velázquez-Becerra, Crisanto

    2015-01-01

    The kingdom Fungi is represented by a large number of organisms, including pathogens that deteriorate the main structural components of wood, such as cellulose, hemicellulose and lignin. The aim of our work was to characterize the antifungal activity in Arthrobacter agilis UMCV2 and diverse amines against wood-decaying fungi. Four fungal organisms (designated as UMTM) were isolated from decaying wood samples obtained from a forest in Cuanajo-Michoacán, México. Two of them showed a clear enzymatic activity of cellulases, xylanases and oxido-reducing enzymes and were identified as Hypocrea (UMTM3 isolate) and Fusarium (UMTM13 isolate). In vitro, the amines showed inhibitory effect against UMTM growth and one of the amines, dimethylhexadecylamine (DMA16), exhibited strong potential as wood preventive treatment, against the attack of decaying fungi. Copyright © 2015 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  18. Environmental radioactivity in the antarctic station

    International Nuclear Information System (INIS)

    Gonzalez, S.; Osores, J.; Martinez, J.; Lopez, E.; Jara, R.

    1998-01-01

    Study about environmental radioactivity in the Peruvian antarctic station Machu Pichu they were carried out during the last three periods to the southern summer. The objective of the project it is to evaluate environmental component in order to elaborate a study it base on the levels background radioactivity and artificial in the antarctic region

  19. Carbon dioxide emissions of Antarctic tourism

    NARCIS (Netherlands)

    Farreny, R.; Oliver-Solà, J.; Lamers, M.A.J.; Amelung, B.; Gabarrell, X.; Rieradevall, J.; Boada, M.; Benayas, J.

    2011-01-01

    The increase of tourism to the Antarctic continent may entail not only local but also global environmental impacts. These latter impacts, which are mainly caused by transport, have been generally ignored. As a result, there is a lack of data on the global impacts of Antarctic tourism in terms of

  20. Impact of climate change on Antarctic krill

    NARCIS (Netherlands)

    Florentino De Souza Silva, A.P.; Atkinson, A.; Kawaguchi, S.; Bravo Rebolledo, E.; Franeker, van J.A.

    2012-01-01

    Antarctic krill Euphausia superba (hereafter ‘krill’) occur in regions undergoing rapid environmental change, particularly loss of winter sea ice. During recent years, harvesting of krill has increased, possibly enhancing stress on krill and Antarctic ecosystems. Here we review the overall impact of

  1. South African antarctic biological research programme

    CSIR Research Space (South Africa)

    SASCAR

    1981-07-01

    Full Text Available This document provides a description of the past, current and planned South African biological research activities in the sub-Antarctic and Antarctic regions. Future activities will fall under one of the five components of the research programme...

  2. Testing oils in antarctic soils

    International Nuclear Information System (INIS)

    Leufkens, D.

    2001-01-01

    The resident seals, whales and penguins in Antarctica's Ross Sea region have only environmentally friendly ways of getting around. In contrast, wherever humans go in the Antarctic and whatever they do, be it research, tourism or fishing, they need fuel for their planes, icebreaker ships, land vehicles and generators. Because of this, petroleum hydrocarbons are the most likely source of pollution in the Antarctic. Accidental oil spills often occur near scientific stations, where storage and refuelling of aircraft and vehicles can result in spills. Spills also occur as a consequence of drilling activities. Dr Jackie Aislabie, a microbiologist from the New Zealand government's research company Landcare Research, is leading a program aimed at understanding how oil spills impact on Antarctic soils. The properties of pristine soils were compared with oil-contaminated soil at three locations: Scott Base, Marble Point and in the Wright Valley at Bull Pass. Soils in the Scott Base area are impacted by the establishment and continuous habitation of the base over 40 years, and a hydrocarbon-contaminated site was sampled near a former storage area for drums of mixed oils. Soil sampled from Marble Point was taken from near the old Marble Point camp, which was inhabited from 1957 to about 1963. Oil stains were visible on the soil surface, and are assumed to have been there for more than 30 years. The samples selected for analysis from the Wright Valley came from a spill site near Bull Pass that occurred during seismic bore-hole drilling activities in 1985. The contamination levels ranged from below detection to just over 29,000 μg/g of soil. Descriptions and analyse results are included into a Geographic Information System and associated soils database

  3. Reshaping the Antarctic Circumpolar Current via Antarctic Bottom Water Export

    Science.gov (United States)

    Stewart, A.; Hogg, A.

    2016-02-01

    Westerly wind forcing of Antarctic Circumpolar Current (ACC) is balanced at large-scale topographic obstructions by form drag; the formation of standing meanders produces a net westward pressure gradient associated with the geostrophically balanced meridional flow. These topographic obstructions also support the northward geostrophic flow of Antarctic Bottom Water (AABW), which piles up dense water on the eastern side of the topography and thereby acts to reduce the form drag. We therefore hypothesize that variations in the density of AABW and its export rate must be accommodated by reshaping the ACC's standing meanders in order to preserve the zonal force balance. We test this hypothesis using an idealized, eddy-resolving sector model of the ACC. We find that response of the ACC to switching off AABW production depends on whether the topography is high enough to block barotropic potential vorticity (PV) contours. If re-entrant PV contours exist then the ACC responds similarly to switching off AABW production or halving the westerly wind strength: for example the ACC transport drops by 10-20% and the surface speed in the meander decreases by around 25%. If PV contours are blocked then the ACC transport becomes insensitive to the westerlies, but switching off AABW production still leads to a reduced ACC transport through a wider, slower meander. These results suggest that the warming and freshening of AABW observed in recent decades may have a detectable impact on the surface circulation of the ACC.

  4. Anti-inflammatory activity in selected Antarctic benthic organisms

    Directory of Open Access Journals (Sweden)

    Juan eMoles

    2014-07-01

    Full Text Available Antarctic benthos was prospected in search for anti-inflammatory activity in polar benthic invertebrates, in two different geographical areas: deep-bottoms of the Eastern Weddell Sea and shallow-waters of the South Shetland Islands. A total of 36 benthic algae and invertebrate species were selected to perform solubility tests in order to test them for anti-inflammatory activity. From these, ethanol extracts of ten species from five different phyla resulted suitable to be studied in cell macrophage cultures (RAW 264.7. Cytotoxicity (MTT method and production of inflammatory mediators (prostaglandin E2, leukotriene B4, interleukin-1 were determined at three extract concentrations (50, 125, 250 g/mL. Bioassays resulted in four different species showing anti-inflammatory activity corresponding to three sponges: Mycale (Oxymycale acerata, Isodictya erinacea, and I. toxophila; and one hemichordate: Cephalodiscus sp. These results show that Antarctic sessile invertebrates may have great value as a source of lead compounds with potential pharmaceutical applications.

  5. New and interesting species of the genus Muelleria (Bacillariophyta) from the Antarctic region and South Africa

    Science.gov (United States)

    Van De Vijver, B.; Mataloni, G.; Stanish, L.; Spaulding, S.A.

    2010-01-01

    During a survey of the terrestrial diatom flora of some sub-Antarctic islands in the southern Indian and Atlantic Oceans and of the Antarctic continent, more than 15 taxa belonging to the genus Muelleria were observed. Nine of these taxa are described as new species using light and scanning electron microscopy. Comments are made on their systematic position and how they are distinguished from other species in the genus. Additionally, two previously unrecognized taxa within the genus were discovered in samples from South Africa. One of these, Muelleria taylorii Van de Vijver & Cocquyt sp. nov., is new to science; the other, Muelleria vandermerwei (Cholnoky) Van de Vijver & Cocquyt nov. comb., had been included in the genus Diploneis. The large number of new Muelleria taxa on the (sub)-Antarctic locations is not surprising. Species in Muelleria occur rarely in collections; in many habitats, it is unusual to find more than 1-2 valves in any slide preparation. As a result, records are scarce. The practice of "force-fitting" (shoehorning) specimens into descriptions from common taxonomic keys (and species drift) results in European species, such as M. gibbula and M. linearis, being applied to Antarctic forms in ecological studies. Finally, the typical terrestrial habitats of soils, mosses and ephemeral water bodies of most of these taxa have been poorly studied in the past.

  6. Imported anthropogenic bacteria may survive the Antarctic winter and introduce new genes into local bacterial communities

    Directory of Open Access Journals (Sweden)

    Brat Kristian

    2016-03-01

    Full Text Available We studied dynamic changes in anthropogenic bacterial communities at a summer-operated Czech research base (the Mendel Research Station in the Antarctic during 2012 and 2013. We observed an increase in total numbers of detected bacteria between the beginning and the end of each stay in the Antarctic. In the first series of samples, bacteria of Bacillus sp. predominated. Surprisingly, high numbers of Gram-positive cocci and coliforms were found (including opportunistic human pathogens, although the conditions for bacterial life were unfavourable (Antarctic winter. In the second series of samples, coliforms and Gram-positive cocci predominated. Dangerous human pathogens were also detected. Yersinia enterocolitica was identified as serotype O:9. Antibiotic susceptibility testing showed medium-to-high resistance rates to ampicillin, cefalotin, cefuroxime, amoxicillin-clavulanate and gentamicin in Enterobacteriaceae. 16S rRNA sequencing showed high rates of accordance between nucleotide sequences among the tested strains. Three conclusions were drawn: (1 Number of anthropogenic bacteria were able to survive the harsh conditions of the Antarctic winter (inside and outside the polar station. Under certain circumstances (e.g. impaired immunity, the surviving bacteria might pose a health risk to the participants of future expeditions or to other visitors to the base. (2 The bacteria released into the outer environment might have impacts on local ecosystems. (3 New characteristics (e.g. resistance to antibiotics may be introduced into local bacterial communities.

  7. Underwater Optics in Sub-Antarctic and Antarctic Coastal Ecosystems.

    Directory of Open Access Journals (Sweden)

    Pirjo Huovinen

    Full Text Available Understanding underwater optics in natural waters is essential in evaluating aquatic primary production and risk of UV exposure in aquatic habitats. Changing environmental conditions related with global climate change, which imply potential contrasting changes in underwater light climate further emphasize the need to gain insights into patterns related with underwater optics for more accurate future predictions. The present study evaluated penetration of solar radiation in six sub-Antarctic estuaries and fjords in Chilean North Patagonian region (39-44°S and in an Antarctic bay (62°S. Based on vertical diffuse attenuation coefficients (Kd, derived from measurements with a submersible multichannel radiometer, average summer UV penetration depth (z1% in these water bodies ranged 2-11 m for UV-B (313 nm, 4-27 m for UV-A (395 nm, and 7-30 m for PAR (euphotic zone. UV attenuation was strongest in the shallow Quempillén estuary, while Fildes Bay (Antarctica exhibited the highest transparency. Optically non-homogeneous water layers and seasonal variation in transparency (lower in winter characterized Comau Fjord and Puyuhuapi Channel. In general, multivariate analysis based on Kd values of UV and PAR wavelengths discriminated strongly Quempillén estuary and Puyuhuapi Channel from other study sites. Spatial (horizontal variation within the estuary of Valdivia river reflected stronger attenuation in zones receiving river impact, while within Fildes Bay a lower spatial variation in water transparency could in general be related to closeness of glaciers, likely due to increased turbidity through ice-driven processes. Higher transparency and deeper UV-B penetration in proportion to UV-A/visible wavelengths observed in Fildes Bay suggests a higher risk for Antarctic ecosystems reflected by e.g. altered UV-B damage vs. photorepair under UV-A/PAR. Considering that damage repair processes often slow down under cool temperatures, adverse UV impact could be

  8. The changing form of Antarctic biodiversity.

    Science.gov (United States)

    Chown, Steven L; Clarke, Andrew; Fraser, Ceridwen I; Cary, S Craig; Moon, Katherine L; McGeoch, Melodie A

    2015-06-25

    Antarctic biodiversity is much more extensive, ecologically diverse and biogeographically structured than previously thought. Understanding of how this diversity is distributed in marine and terrestrial systems, the mechanisms underlying its spatial variation, and the significance of the microbiota is growing rapidly. Broadly recognizable drivers of diversity variation include energy availability and historical refugia. The impacts of local human activities and global environmental change nonetheless pose challenges to the current and future understanding of Antarctic biodiversity. Life in the Antarctic and the Southern Ocean is surprisingly rich, and as much at risk from environmental change as it is elsewhere.

  9. Carbonate Deposition on Antarctic Shelves

    Science.gov (United States)

    Frank, T. D.; James, N. P.; Malcolm, I.

    2011-12-01

    Limestones associated with glaciomarine deposits occur throughout the geologic record but remain poorly understood. The best-described examples formed during major ice ages of the Neoproterozoic and Late Paleozoic. Quaternary analogs on Antarctic shelves have received comparatively little study. Here, we report on the composition, spatial distribution, and stratigraphic context of carbonate sediments contained in piston cores from the Ross Sea. The goals of this work are to (1) document the nature and distribution of carbonate sediments on the Ross Sea continental shelf and (2) examine temporal relationships to Quaternary glaciation. Results will be used to develop criteria that will improve understanding of analogous deposits in the ancient record. All carbonate-rich intervals in piston cores from the Ross Rea, now housed at the Antarctic Marine Geology Research Facility at Florida State University, were examined and described in detail. Sediment samples were disaggregated and sieved into size fractions before description with paleontological analysis carried out on the coarsest size fraction (>250 microns). Carbonate-rich sediments are concentrated in the northwestern Ross Sea, along the distal margins of Mawson and Pennell Banks. Calcareous facies include a spectrum of lithologies that range from fossiliferous mud, sand, and gravel to skeletal floatstone-rudstone and bafflestone. Floatstone-rudstone and bafflestone is most abundant along western-facing slopes in areas protected from the Antarctic Coastal Current. Sand-prone facies dominate the tops of banks and mud-prone, often spicultic, facies occur in deeper areas. The carbonate factory is characterized by a low-diversity, heterozoan assemblage that is dominated by stylasterine hydrocorals, barnacles, and bryozoans. Molluscs and echinoids are present but not abundant. Planktic and benthic foraminifera are ubiquitous components of the sediment matrix, which is locally very rich in sponge spicules. Biota rarely

  10. Bacterial diversity of autotrophic enriched cultures from remote, glacial Antarctic, Alpine and Andean aerosol, snow and soil samples

    Science.gov (United States)

    González-Toril, E.; Amils, R.; Delmas, R. J.; Petit, J.-R.; Komárek, J.; Elster, J.

    2009-01-01

    Four different communities and one culture of autotrophic microbial assemblages were obtained by incubation of samples collected from high elevation snow in the Alps (Mt. Blanc area) and the Andes (Nevado Illimani summit, Bolivia), from Antarctic aerosol (French station Dumont d'Urville) and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas), in a minimal mineral (oligotrophic) media. Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. Phylogenetic comparison with the currently available rDNA database allowed sequences belonging to Proteobacteria Alpha-, Beta- and Gamma-proteobacteria), Actinobacteria and Bacteroidetes phyla to be identified. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified) and the marine Antarctic soil the poorest (only one). Snow samples from Col du Midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones). These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteriaclone). The only microorganism identified in the Antarctica soil (Brevundimonas sp.) was also detected in the Antarctic aerosol. Most of the identified microorganisms had been detected previously in cold environments, marine sediments soils and rocks. Air current dispersal is the best model to explain the presence of very specific microorganisms, like those identified in this work, in environments very distant and very different from each other.

  11. Antarctic Subglacial Lake Classification Inventory, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is an Antarctic radar-based subglacial lake classification collection, which focuses on the radar reflection properties of each given lake.

  12. Abundance, viability and culturability of Antarctic bacteria

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; DeSouza, M.J.B.D.; Nair, S.; Chandramohan, D.

    The viability of total number of bacteria decide the mineralisation rate in any ecosystem and ultimately the fertility of the region. This study aims at establishing the extent of viability in the standing stock of the Antarctic bacterial population...

  13. Historical Arctic and Antarctic Surface Observational Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This product consists of meteorological data from 105 Arctic weather stations and 137 Antarctic stations, extracted from the National Climatic Data Center (NCDC)'s...

  14. South African Antarctic earth science research programme

    CSIR Research Space (South Africa)

    SASCAR

    1984-02-01

    Full Text Available This document describes the past, current and planned future South African earth science research programme in the Antarctic, Southern Ocean and subantarctic regions. The scientific programme comprises five components into which present and future...

  15. Edwardsiella andrillae, a New Species of Sea Anemone from Antarctic Ice

    Science.gov (United States)

    Daly, Marymegan; Rack, Frank; Zook, Robert

    2013-01-01

    Exploration of the lower surface of the Ross Ice Shelf in Antarctica by the Submersible Capable of under-Ice Navigation and Imaging (SCINI) remotely operated vehicle discovered a new species of sea anemone living in this previously undocumented ecosystem. This discovery was a significant outcome of the Coulman High Project’s geophysical and environmental fieldwork in 2010-2011 as part of the ANDRILL (ANtarctic geologic DRILLing) program. Edwardsiella andrillae n. sp., lives with most of its column in the ice shelf, with only the tentacle crown extending into the seawater below. In addition to being the only Antarctic representative of the genus, Edwardsiella andrillae is distinguished from all other species of the genus in the number of tentacles and in the size and distribution of cnidae. The anatomy and histology of Edwardsiella andrillae present no features that explain how this animal withstands the challenges of life in such an unusual habitat. PMID:24349517

  16. Edwardsiella andrillae, a new species of sea anemone from Antarctic ice.

    Directory of Open Access Journals (Sweden)

    Marymegan Daly

    Full Text Available Exploration of the lower surface of the Ross Ice Shelf in Antarctica by the Submersible Capable of under-Ice Navigation and Imaging (SCINI remotely operated vehicle discovered a new species of sea anemone living in this previously undocumented ecosystem. This discovery was a significant outcome of the Coulman High Project's geophysical and environmental fieldwork in 2010-2011 as part of the ANDRILL (ANtarctic geologic DRILLing program. Edwardsiella andrillae n. sp., lives with most of its column in the ice shelf, with only the tentacle crown extending into the seawater below. In addition to being the only Antarctic representative of the genus, Edwardsiella andrillae is distinguished from all other species of the genus in the number of tentacles and in the size and distribution of cnidae. The anatomy and histology of Edwardsiella andrillae present no features that explain how this animal withstands the challenges of life in such an unusual habitat.

  17. Ross Ice Shelf, Antarctic Ice and Clouds

    Science.gov (United States)

    1991-01-01

    In this view of Antarctic ice and clouds, (56.5S, 152.0W), the Ross Ice Shelf of Antarctica is almost totally clear, showing stress cracks in the ice surface caused by wind and tidal drift. Clouds on the eastern edge of the picture are associated with an Antarctic cyclone. Winds stirred up these storms have been known to reach hurricane force.

  18. Volcanic deposits in Antarctic snow and ice

    Science.gov (United States)

    Delmas, Robert J.; Legrand, Michel; Aristarain, Alberto J.; Zanolini, FrançOise

    1985-12-01

    Major volcanic eruptions are able to spread large amounts of sulfuric acid all over the world. Acid layers of volcanic origin were detected for the first time a few years ago by Hammer in Greenland ice. The present paper deals with volcanic deposits in the Antarctic. The different methods that can be used to find volcanic acid deposits in snow and ice cores are compared: electrical conductivity, sulfate, and acidity measurements. Numerous snow and ice samples collected at several Antarctic locations were analyzed. The results reveal that the two major volcanic events recorded by H2SO4, fallout in Antarctic ice over the last century are the eruptions of Krakatoa (1883) and Agung (1963), both located at equatorial latitudes in the southern hemisphere. The volcanic signals are found to be particularly well defined at central Antarctic locations apparently in relation to the low snow accumulation rates in these areas. It is demonstrated that volcanic sulfuric acid in snow is not even partially neutralized by ammonia. The possible influence of Antarctic volcanic activity on snow chemistry is also discussed, using the three recent eruptions of the Deception Island volcano as examples. Only one of them seems to have had a significant effect on the chemistry of snow at a location 200 km from this volcano. It is concluded that Antarctic volcanic ice records are less complicated than Greenland records because of the limited number of volcanos in the southern hemisphere and the apparently higher signal to background ratio for acidity in Antarctica than in Greenland.

  19. Ecology of antarctic marine sponges: an overview.

    Science.gov (United States)

    McClintock, James B; Amsler, Charles D; Baker, Bill J; van Soest, Rob W M

    2005-04-01

    Sponges are important components of marine benthic communities of Antarctica. Numbers of species are high, within the lower range for tropical latitudes, similar to those in the Arctic, and comparable or higher than those of temperate marine environments. Many have circumpolar distributions and in some habitats hexactinellids dominate benthic biomass. Antarctic sponge assemblages contribute considerable structural heterogeneity for colonizing epibionts. They also represent a significant source of nutrients to prospective predators, including a suite of spongivorous sea stars whose selective foraging behaviors have important ramifications upon community structure. The highly seasonal plankton blooms that typify the Antarctic continental shelf are paradoxical when considering the planktivorous diets of sponges. Throughout much of the year Antarctic sponges must either exploit alternate sources of nutrition such as dissolved organic carbon or be physiologically adapted to withstand resource constraints. In contrast to predictions that global patterns of predation should select for an inverse correlation between latitude and chemical defenses in marine sponges, such defenses are not uncommon in Antarctic sponges. Some species sequester their defensive metabolites in the outermost layers where they are optimally effective against sea star predation. Secondary metabolites have also been shown to short-circuit molting in sponge-feeding amphipods and prevent fouling by diatoms. Coloration in Antarctic sponges may be the result of relict pigments originally selected for aposematism or UV screens yet conserved because of their defensive properties. This hypothesis is supported by the bioactive properties of pigments examined to date in a suite of common Antarctic sponges.

  20. Evaluation of Arthrobacter aurescens Strain TC1 as Bioaugmentation Bacterium in Soils Contaminated with the Herbicidal Substance Terbuthylazine

    Science.gov (United States)

    Silva, Vera P.; Moreira-Santos, Matilde; Mateus, Carla; Teixeira, Tânia; Ribeiro, Rui; Viegas, Cristina A.

    2015-01-01

    In the last years the chloro-s-triazine active substance terbuthylazine has been increasingly used as an herbicide and may leave residues in the environment which can be of concern. The present study aimed at developing a bioaugmentation tool based on the soil bacterium Arthrobacter aurescens strain TC1 for the remediation of terbuthylazine contaminated soils and at examining its efficacy for both soil and aquatic compartments. First, the feasibility of growing the bioaugmentation bacterium inocula on simple sole nitrogen sources (ammonium and nitrate) instead of atrazine, while still maintaining its efficiency to biodegrade terbuthylazine was shown. In sequence, the successful and quick (3 days) bioremediation efficacy of ammonium-grown A. aurescens TC1 cells was proven in a natural soil freshly spiked or four-months aged with commercial terbuthylazine at a dose 10× higher than the recommended in corn cultivation, to mimic spill situations. Ecotoxicity assessment of the soil eluates towards a freshwater microalga supported the effectiveness of the bioaugmentation tool. Obtained results highlight the potential to decontaminate soil while minimizing terbuthylazine from reaching aquatic compartments via the soil-water pathway. The usefulness of this bioaugmentation tool to provide rapid environment decontamination is particularly relevant in the event of accidental high herbicide contamination. Its limitations and advantages are discussed. PMID:26662024

  1. Biodegradation of p-nitrophenol using Arthrobacter chlorophenolicus A6 in a novel upflow packed bed reactor.

    Science.gov (United States)

    Sahoo, Naresh Kumar; Pakshirajan, Kannan; Ghosh, Pranab Kumar

    2011-06-15

    A novel packed bed reactor (PBR) was designed with cross flow aeration at multiple ports along the depth to improve the hydrodynamic conditions of the reactor, and the biodegradation efficiency of Arthrobacter chlorophenolicus A6 on p-nitrophenol (PNP) removal in PBR at different PNP loading rates were evaluated. The novel PBR was designed to improve the hydrodynamic features such as mixing time profile (t(m95)), oxygen mass transfer coefficient (k(L)a), and overall gas hold up capacity (ɛ(G)) of the reactor. PNP concentration in the influent was varied between 600 and 1400 mg l(-1) whereas the hydraulic retention time (HRT) in the reactor was varied between 18 and 7.5h. Complete removal of PNP was achieved in the reactor up to a PNP loading rate of 2787 mg l(-1)d(-1). More than 99.9% removal of PNP was achieved in the reactor for an influent concentration of 1400 mg l(-1) and at 18 h HRT. In the present study, PNP was utilized as sole source of carbon and energy by A. chlorophenolicus A6. Furthermore, the bioreactor showed good compatibility in handling shock loading of PNP. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Biodegradation of 4-bromophenol by Arthrobacter chlorophenolicus A6T in a newly designed packed bed reactor.

    Science.gov (United States)

    Sahoo, Naresh Kumar; Ghosh, Pranab Kumar; Pakshirajan, Kannan

    2013-02-01

    Bromophenol is listed as a priority pollutant by the U.S. EPA. However, there has been no report on the removal of bromophenol in any biological system that is operated in a continuous mode. The efficiency of Arthrobacter chlorophenolicus A6(T) on the biodegradation of 4-bromophenol (4-BP) in a newly designed packed bed reactor (PBR) was evaluated with different influent 4-BP concentrations between 400 mg l(-1) and 1200 mg l(-1) and hydraulic retention times (HRTs) between 24 h and 7.5 h. The response of the PBR to 4-BP shock loadings was also tested, and the bioreactor was found to adequately handle these shock loadings. The percentage of effluent toxicity in the PBR was tested using mixed microbial consortia as the test species; this experiment was performed using a 4-BP influent concentration of 1200 mg l(-1) and HRTs between 24 h and 7.5 h. A maximal 98% effluent toxicity removal was achieved when the PBR was operated at an HRT of 24 h. In the present study, 4-BP was used as the sole source of carbon and energy, and the complete removal of 4-BP was achieved with 4-BP loading rates of up to 2277 mg l(-1) day(-1). Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  3. Flavobacterium nitratireducens sp. nov., an amylolytic bacterium of the family Flavobacteriaceae isolated from coastal surface seawater

    Digital Repository Service at National Institute of Oceanography (India)

    Nupur; Bhumika, V.; Srinivas, T.N.R.; AnilKumar, P.

    . Nogi, Y., Soda, K. & Oikawa, T. (2005). Flavobacterium frigidimaris sp. nov., isolated from Antarctic seawater. Syst Appl Microbiol 28, 310-315. Ryu, S. H., Park, J. H., Moon, J. C., Sung, Y., Lee, S. S. & Jeon, C. O. (2008). Flavobacterium...

  4. Health aspects of Antarctic tourism.

    Science.gov (United States)

    Prociv, P

    1998-12-01

    Increasing numbers of seaborne tourists are visiting Antarctica, with most coming from the United States (3503 in 1996-97), Germany (777), and Australia (680; cf. 356 in 1994-95 and 410 in 1995-96). The impression among travel medicine clinicians is that, each year, more prospective travelers seek advice about the health demands of this type of adventure, mostly relating to fitness for travel, exposure to extreme cold, hazards in ice and snow, and other potential health risks. This is a recent phenomenon. While a regular shipping service had been established between the Falklands and the subantarctic islands of South Georgia and the South Shetlands by 1924, the first documented tourists accompanied an Argentine expedition to the South Orkneys in 1933.1 Commercial airline flights over these islands and the Antarctic Peninsula began in 1956, from Chile, and recreational cruises to the Peninsula began in 1958. Tourist numbers subsequently grew slowly, for what was clearly an exclusive and very expensive undertaking, with few ships available for these hazardous voyages. From 1957 to 1993, 37,000 tourists visited by sea, most seeing only the Peninsula.2 The dramatic recent growth in numbers is a consequence of the collapse of the Soviet Union. The small fleet of ice-strengthened research vessels and working icebreakers, which was made redundant by withdrawal of central government support from isolated communities and military activities along the northern coast of Siberia (and from Antarctic research bases), now accounts for the bulk of charter-cruise tourism to Antarctica, at competitive prices. According to the International Association of Antarctica Tour Operators,3 7322 people traveled to Antarctica on commercially organized voyages in the 1996-97 season, and a record 10,000 shipborne visitors were expected for the 1997-98 season (November-March), traveling mainly from South America to the Peninsula on 15 ice-reinforced vessels, each carrying between 36 and 180

  5. Antarctic station life: The first 15 years of mixed expeditions to the Antarctic

    Science.gov (United States)

    Sarris, Aspa

    2017-02-01

    This study examined the experiences of women who lived and worked on remote and isolated Antarctic stations for up to 15 months at a time. The study employed purposeful sampling and a longitudinal - processual approach to study women's experiences over the first 15 years of mixed gender Antarctic expeditions. The retrospective analysis was based on a semi-structured interview administered to 14 women upon their return to Australia. The results showed that women referred to the natural physical Antarctic environment as one of the best aspects of their experience and the reason they would recommend the Antarctic to their friends as a good place to work. In describing the worst aspect of their experience, women referred to aspects of Antarctic station life, including: (i) the male dominated nature of station culture; (ii) the impact of interpersonal conflict, including gender based conflict and friction between scientists and trades workers; and (iii) the lack of anonymity associated with living and working with the same group of individuals, mainly men, for up to 12 months or more. The results are discussed within the context of the evolution of Antarctic station culture and recommendations are made in terms of the demography of expeditions, expeditioner selection and recruitment and the ongoing monitoring of Antarctic station culture. The study presents a framework that can be applied to groups and teams living and working in analogous isolated, confined and extreme work environments, including outer space missions.

  6. High-level production of Arthrobacter aurescens CYC705 nitrilase in Escherichia coli for biosynthesis of iminodiacetic acid.

    Science.gov (United States)

    Su, Erzheng; Lu, Chao; Ma, Xiaoqiang; Cai, Wenwen; Zhu, Shujing

    2016-07-01

    Nitrilase from Arthrobacter aurescens CYC705 can hydrolyze the iminodiacetonitrile to iminodiacetic acid (IDA) efficiently, and its high-level production in Escherichia coli has not been established. In the present work, the production of this nitrilase expressed in E. coli BL21(DE3) with a recombinant plasmid pET28a-cyc705 was optimized. Various culture conditions and process parameters including medium components and concentrations, inducer types and concentrations, inducing temperature and time were systematically examined in a shake flask. After optimization, the OD600 , nitrilase activity, and productivity were obviously improved and achieved to 40.91 ± 1.341, 98.12 ± 1.248 U/mL, and 2,230 ± 28.36 U L(-1)  H(-1) , respectively, about 2.1-, 30-, and 33-fold increases as compared with those in the primary medium. Furthermore, four different fermentation strategies were adopted to scale up cultivation of the recombinant E. coli BL21(DE3)/pET28a-cyc705 in a 3.7-L fermenter. Substituting the peanut powder with fish peptone and accompanying with 1.0% glycerol feeding could significantly reduce the bubble production and shorten the fermentation time, which resulted in a nitrilase productivity of 4,653 ± 38.16 U L(-1) H(-1) that was about two times higher than that in a shake flask. The high-level production of A. aurescens CYC705 nitrilase established in this study will meet the need of industrial biosynthesis of IDA. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

  7. Complete genome sequence of Arthrobacter alpinus ERGS4:06, a yellow pigmented bacterium tolerant to cold and radiations isolated from Sikkim Himalaya.

    Science.gov (United States)

    Kumar, Rakshak; Singh, Dharam; Swarnkar, Mohit Kumar; Singh, Anil Kumar; Kumar, Sanjay

    2016-02-20

    Arthrobacter alpinus ERGS4:06, a yellow pigmented bacterium which exhibited tolerance to cold and UV radiations was isolated from the glacial stream of East Rathong glacier in Sikkim Himalaya. Here we report the 4.3Mb complete genome assembly that has provided the basis for potential role of pigments as a survival strategy to combat stressed environment of cold and high UV-radiation and additionally the ability to produce cold active industrial enzymes. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Meteorological observatory for Antarctic data collection

    International Nuclear Information System (INIS)

    Grigioni, P.; De Silvestri, L.

    1996-01-01

    In the last years, a great number of automatic weather stations was installed in Antarctica, with the aim to examine closely the weather and climate of this region and to improve the coverage of measuring points on the Antarctic surface. In 1987 the Italian Antarctic Project started to set up a meteorological network, in an area not completely covered by other countries. Some of the activities performed by the meteorological observatory, concerning technical functions such as maintenance of the AWS's and the execution of radio soundings, or relating to scientific purposes such as validation and elaboration of collected data, are exposed. Finally, some climatological considerations on the thermal behaviour of the Antarctic troposphere such as 'coreless winter', and on the wind field, including katabatic flows in North Victoria Land are described

  9. NEW FRONTIERS OF ANTARCTIC SUBGLACIAL LAKES EXPLORATION

    Directory of Open Access Journals (Sweden)

    Pavel Talalay

    2013-01-01

    Full Text Available Antarctic subglacial aquatic environment have become of great interest to the science community because they may provide unique information about microbial evolution, the past climate of the Earth, and the formation of the Antarctic ice sheet. Nowadays it is generally recognized that a vast network of lakes, rivers, and streams exists thousands of meters beneath Antarctic Ice Sheets. Up to date only four boreholes accessed subglacial aquatic system but three of them were filled with high-toxic drilling fluid, and the subglacial water was contaminated. Two recent exploration programs proposed by UK and USA science communities anticipate direct access down to the lakes Ellsworth and Whillans, respectively, in the 2012/2013 Antarctic season. A team of British scientists and engineers engage in the first attempt to drill into Lake Ellsworth but failed. US research team has successfully drilled through 800 m of Antarctic ice to reach a subglacial lake Whillans and retrieve water and sediment samples. Both activities used hot-water drilling technology to access lakes. The main troublesome of the implemented and planned projects for accessing of Antarctic subglacial lakes is connected with the hydrostatic unbalance resulted in the upwelling of water into the hole with subsequent difficulties. The proposed RECoverable Autonomous Sonde “RECAS” would measure and sample subglacial water while subglacial lake is reliably isolated from surface environment, and at the same time the sonde is able to measure geochemical signals in situ throughout the depth of ice sheet on the way to the bed. All process is going on in semi-automatic mode, and the estimated duration of subglacial lake exploration at the depth of 3500 m is 8–9 months. The general concept of the sonde as well as proposed power-supply and performance are given.

  10. Reconsidering connectivity in the sub-Antarctic.

    Science.gov (United States)

    Moon, Katherine L; Chown, Steven L; Fraser, Ceridwen I

    2017-11-01

    Extreme and remote environments provide useful settings to test ideas about the ecological and evolutionary drivers of biological diversity. In the sub-Antarctic, isolation by geographic, geological and glaciological processes has long been thought to underpin patterns in the region's terrestrial and marine diversity. Molecular studies using increasingly high-resolution data are, however, challenging this perspective, demonstrating that many taxa disperse among distant sub-Antarctic landmasses. Here, we reconsider connectivity in the sub-Antarctic region, identifying which taxa are relatively isolated, which are well connected, and the scales across which this connectivity occurs in both terrestrial and marine systems. Although many organisms show evidence of occasional long-distance, trans-oceanic dispersal, these events are often insufficient to maintain gene flow across the region. Species that do show evidence of connectivity across large distances include both active dispersers and more sedentary species. Overall, connectivity patterns in the sub-Antarctic at intra- and inter-island scales are highly complex, influenced by life-history traits and local dynamics such as relative dispersal capacity and propagule pressure, natal philopatry, feeding associations, the extent of human exploitation, past climate cycles, contemporary climate, and physical barriers to movement. An increasing use of molecular data - particularly genomic data sets that can reveal fine-scale patterns - and more effective international collaboration and communication that facilitates integration of data from across the sub-Antarctic, are providing fresh insights into the processes driving patterns of diversity in the region. These insights offer a platform for assessing the ways in which changing dispersal mechanisms, such as through increasing human activity and changes to wind and ocean circulation, may alter sub-Antarctic biodiversity patterns in the future. © 2017 Cambridge

  11. Purification and characterization of cold-adapted beta-agarase from an Antarctic psychrophilic strain

    Directory of Open Access Journals (Sweden)

    Jiang Li

    2015-09-01

    Full Text Available An extracellular β-agarase was purified from Pseudoalteromonas sp. NJ21, a Psychrophilic agar-degrading bacterium isolated from Antarctic Prydz Bay sediments. The purified agarase (Aga21 revealed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular weight of 80 kDa. The optimum pH and temperature of the agarase were 8.0 and 30 °C, respectively. However, it maintained as much as 85% of the maximum activities at 10 °C. Significant activation of the agarase was observed in the presence of Mg2+, Mn2+, K+; Ca2+, Na+, Ba2+, Zn2+, Cu2+, Co2+, Fe2+, Sr2+ and EDTA inhibited the enzyme activity. The enzymatic hydrolyzed product of agar was characterized as neoagarobiose. Furthermore, this work is the first evidence of cold-adapted agarase in Antarctic psychrophilic bacteria and these results indicate the potential for the Antarctic agarase as a catalyst in medicine, food and cosmetic industries.

  12. Environmental change and Antarctic seabird populations.

    Science.gov (United States)

    Croxall, J P; Trathan, P N; Murphy, E J

    2002-08-30

    Recent changes in Antarctic seabird populations may reflect direct and indirect responses to regional climate change. The best long-term data for high-latitude Antarctic seabirds (Adélie and Emperor penguins and snow petrels) indicate that winter sea-ice has a profound influence. However, some effects are inconsistent between species and areas, some in opposite directions at different stages of breeding and life cycles, and others remain paradoxical. The combination of recent harvest driven changes and those caused by global warming may produce rapid shifts rather than gradual changes.

  13. SP. Pescado

    Directory of Open Access Journals (Sweden)

    Renato Gendre

    2003-12-01

    Full Text Available Nell'occhiello di un articolo dal titolo Il Peru dei de[Jini rosa e de/la grande pioggia si legge: "da una partenza  in aereo al «pescado»  che ti  sfamera."1 Questa parola spagnola, giustamente chiusa tra caporali, a noi pare molto interes­ sante, perche, nonostante l'apparenza, non ha nulla da spartire sotto i1 profilo se­ mantico con l'it. pescato. lnfatti, tutti i piu importanti dizionari della lingua italiana, di ieri e di oggi, etimologici e non 2, registrano  accanto a pescata,  ii lemma pescato, 3 ma lo spiegano come "quantita di pesce catturato nel corso di una battuta o di una stagione di pesca",4 mentre lo sp. pescado  indica i1 "pesce (solo nel senso di: pesGe pescato da mangiare [...]".s

  14. Crystallization and preliminary X-ray diffraction analysis of cold-active beta-galactosidase from Arthrobacter sp. C2-2

    Czech Academy of Sciences Publication Activity Database

    Petroková, Hana; Vondráčková-Buchtelová, Eva; Skálová, Tereza; Dohnálek, Jan; Lipovová, P.; Spiwok, V.; Strnad, V.; Králová, B.; Hašek, Jindřich

    2005-01-01

    Roč. 70, č. 1 (2005), s. 124-132 ISSN 0010-0765 R&D Projects: GA ČR GA204/02/0843 Keywords : galactosidase s * glycosidases * psychrotrophic Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.949, year: 2005

  15. Galactonolactone inhibiting the active site of beta-galactosidase from Arthrobacter sp. C2-2. Crystal structure at 2.2 Å resolution

    Czech Academy of Sciences Publication Activity Database

    Štěpánková, Andrea; Skálová, Tereza; Dohnálek, Jan; Hašek, Jindřich; Lipovová, P.

    2008-01-01

    Roč. 15, 2a (2008), s. 34 ISSN 1211-5894. [Struktura 2008 - Colloquium of the Czech and Slovak Crystallographic Association. 16.06.2008-20.06.2008, Valtice] R&D Projects: GA ČR GA204/02/0843; GA AV ČR KJB500500512 Institutional research plan: CEZ:AV0Z40500505 Keywords : beta - galactosidase * cold-active enzyme * X-ray structure Subject RIV: CD - Macromolecular Chemistry

  16. Structure changes evoked by binding of ligands into the active site of galactosidase from beta-enzyme Arthrobacter2-2C.sp

    Czech Academy of Sciences Publication Activity Database

    Štěpánková, Andrea; Skálová, Tereza; Dohnálek, Jan; Dušková, Jarmila; Kolenko, Petr; Hašek, Jindřich; Spiwok, V.; Lipovová, P.

    2009-01-01

    Roč. 16, 1a (2009), b6-b7 ISSN 1211-5894. [Discussions in Structural Molecular Biology /7./. 12.03.2009-14.03.2009, Nové Hrady] R&D Projects: GA ČR GA305/07/1073 Institutional research plan: CEZ:AV0Z40500505 Keywords : beta - galactosidase * ligands interactions * active site Subject RIV: CD - Macromolecular Chemistry

  17. Cold active .beta.-galactosidase from Arthrobacter sp. C2-2 forms compact 660 kDa hexamers: crystal structure at 1.9 Ă resolution

    Czech Academy of Sciences Publication Activity Database

    Skálová, Tereza; Dohnálek, Jan; Spiwok, V.; Lipovová, P.; Vondráčková, Eva; Petroková, Hana; Dušková, Jarmila; Strnad, Hynek; Králová, B.; Hašek, Jindřich

    2005-01-01

    Roč. 353, č. 2 (2005), s. 282-294 ISSN 0022-2836 R&D Projects: GA ČR(CZ) GA204/02/0843; GA AV ČR(CZ) KJB500500512 Institutional research plan: CEZ:AV0Z40500505 Keywords : glycosyl hydrolase * . beta .- galactosidase * cold-active Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.229, year: 2005

  18. Protistan communities in the Australian sector of the Sub-Antarctic Zone during SAZ-Sense

    Science.gov (United States)

    de Salas, Miguel F.; Eriksen, Ruth; Davidson, Andrew T.; Wright, Simon W.

    2011-11-01

    Protistan species composition and abundance in the Sub-Antarctic Zone (SAZ) and Polar Front Zone (PFZ) south of Tasmania were determined by microscopy and pigment analysis from samples collected during the Sub-Antarctic Zone—Sensitivity of the sub-Antarctic Zone to Environmental Change (SAZ-Sense) voyage, in January and February of 2007. A primary goal of this voyage was to determine the potential effects of climate change-induced natural iron fertilisation of the SAZ on the protistan community by exploring differences between communities in waters west of Tasmania, which are low in iron, and eastern waters, which are fertilised by continental iron input and mixing across the subtropical front. The SAZ is a sink for anthropogenic CO 2 in spring, but the magnitude of this may vary depending on seasonal changes in protistan abundance, composition and trophodynamics. Protistan species composition and abundance in the western Sub-Antarctic Zone at process station 1 (P1) showed a community in which low carbon biomass was dominated by a Thalassiosira sp., which was very weakly silicified under strong silica limitation. Protistan cell carbon was dominated by diatoms and nano-picoflagellates at process station 2 (P2) in the Polar Front Zone (PFZ), while dinoflagellates dominated in the iron-enriched waters of eastern SAZ at station 3 (P3). Iron enrichment enhanced production and favoured proliferation of small flagellates during summer in the silica-depleted eastern SAZ rather than large diatoms, though the effect this may have on the vertical export of particulate organic carbon (POC) is still unclear.

  19. Antarctic Tephra Database (AntT)

    Science.gov (United States)

    Kurbatov, A.; Dunbar, N. W.; Iverson, N. A.; Gerbi, C. C.; Yates, M. G.; Kalteyer, D.; McIntosh, W. C.

    2014-12-01

    Modern paleoclimate research is heavily dependent on establishing accurate timing related to rapid shifts in Earth's climate system. The ability to correlate these events at local, and ideally at the intercontinental scales, allows assessment, for example, of phasing or changes in atmospheric circulation. Tephra-producing volcanic eruptions are geologically instantaneous events that are largely independent of climate. We have developed a tephrochronological framework for paleoclimate research in Antarctic in a user friendly, freely accessible online Antarctic tephra (AntT) database (http://cci.um.maine.edu/AntT/). Information about volcanic events, including physical and geochemical characteristics of volcanic products collected from multiple data sources, are integrated into the AntT database.The AntT project establishes a new centralized data repository for Antarctic tephrochronology, which is needed for precise correlation of records between Antarctic ice cores (e.g. WAIS Divide, RICE, Talos Dome, ITASE) and global paleoclimate archives. The AntT will help climatologists, paleoclimatologists, atmospheric chemists, geochemists, climate modelers synchronize paleoclimate archives using volcanic products that establishing timing of climate events in different geographic areas, climate-forcing mechanisms, natural threshold levels in the climate system. All these disciplines will benefit from accurate reconstructions of the temporal and spatial distribution of past rapid climate change events in continental, atmospheric, marine and polar realms. Research is funded by NSF grants: ANT-1142007 and 1142069.

  20. The changing form of Antarctic biodiversity

    OpenAIRE

    Chown, Steven L.; Clarke, Andrew; Fraser, Ceridwen I.; Cary, S. Craig; Moon, Katherine L.; McGeoch, Melodie A.

    2015-01-01

    Antarctic biodiversity is much more extensive, ecologically diverse and biogeographically structured than previously thought. Understanding of how this diversity is distributed in marine and terrestrial systems, the mechanisms underlying its spatial variation, and the significance of the microbiota is growing rapidly. Broadly recognizable drivers of diversity variation include energy availability and historical refugia. The impacts of local human activities and global environmental change non...

  1. Evolution of the early Antarctic ice ages

    NARCIS (Netherlands)

    Liebrand, Diederik; de Bakker, Anouk T M|info:eu-repo/dai/nl/371573734; Beddow, Helen M; Wilson, Paul A; Bohaty, Steven M; Ruessink, Gerben|info:eu-repo/dai/nl/169093360; Pälike, Heiko; Batenburg, Sietske J; Hilgen, Frederik J|info:eu-repo/dai/nl/102639876; Hodell, David A; Huck, Claire E; Kroon, Dick; Raffi, Isabella; Saes, Mischa J M; van Dijk, Arnold E|info:eu-repo/dai/nl/341412082; Lourens, Lucas J|info:eu-repo/dai/nl/125023103

    2017-01-01

    Understanding the stability of the early Antarctic ice cap in the geological past is of societal interest because present-day atmospheric CO2 concentrations have reached values comparable to those estimated for the Oligocene and the Early Miocene epochs. Here we analyze a new high-resolution

  2. Low temperature reduction of hexavalent chromium by a microbial enrichment consortium and a novel strain of Arthrobacter aurescens

    Directory of Open Access Journals (Sweden)

    Thompson Vicki S

    2006-01-01

    Full Text Available Abstract Background Chromium is a transition metal most commonly found in the environment in its trivalent [Cr(III] and hexavalent [Cr(VI] forms. The EPA maximum total chromium contaminant level for drinking water is 0.1 mg/l (0.1 ppm. Many water sources, especially underground sources, are at low temperatures (less than or equal to 15 Centigrade year round. It is important to evaluate the possibility of microbial remediation of Cr(VI contamination using microorganisms adapted to these low temperatures (psychrophiles. Results Core samples obtained from a Cr(VI contaminated aquifer at the Hanford facility in Washington were enriched in Vogel Bonner medium at 10 Centigrade with 0, 25, 50, 100, 200, 400 and 1000 mg/l Cr(VI. The extent of Cr(VI reduction was evaluated using the diphenyl carbazide assay. Resistance to Cr(VI up to and including 1000 mg/l Cr(VI was observed in the consortium experiments. Reduction was slow or not observed at and above 100 mg/l Cr(VI using the enrichment consortium. Average time to complete reduction of Cr(VI in the 30 and 60 mg/l Cr(VI cultures of the consortium was 8 and 17 days, respectively at 10 Centigrade. Lyophilized consortium cells did not demonstrate adsorption of Cr(VI over a 24 hour period. Successful isolation of a Cr(VI reducing organism (designated P4 from the consortium was confirmed by 16S rDNA amplification and sequencing. Average time to complete reduction of Cr(VI at 10 Centigrade in the 25 and 50 mg/l Cr(VI cultures of the isolate P4 was 3 and 5 days, respectively. The 16S rDNA sequence from isolate P4 identified this organism as a strain of Arthrobacter aurescens, a species that has not previously been shown to be capable of low temperature Cr(VI reduction. Conclusion A. aurescens, indigenous to the subsurface, has the potential to be a predominant metal reducer in enhanced, in situ subsurface bioremediation efforts involving Cr(VI and possibly other heavy metals and radionuclides.

  3. PLASMID-ENCODED PHTHALATE CATABOLIC PATHWAY IN ARTHROBACTER KEYSERI 12B: BIOTRANSFORMATIONS OF 2-SUBSTITUTED BENZOATES AND THEIR USE IN CLONING AND CHARACTERIZATION OF PHTHALATE CATABOLISM GENES AND GENE PRODUCTS

    Science.gov (United States)

    Several 2-substituted benzoates (including 2-trifluoromethyl-, 2-chloro-, 2-bromo-, 2-iodo-, 2-nitro-, 2-methoxy-, and 2-acetyl-benzoates) were converted by phthalate-grown Arthrobacter keyseri 12B to the corresponding 2-substituted 3,4-dihydroxybenzoates (protocatechuates)...

  4. Characterization of 15 selected coccal bacteria isolated from Antarctic rock and soil samples from the McMurdo-Dry Valleys (South-Victoria Land)

    Science.gov (United States)

    Siebert, J.; Hirsch, P.; Friedmann, E. I. (Principal Investigator)

    1988-01-01

    Approximately 1500 cultures of microorganisms were isolated from rocks and soils of the Ross Desert (McMurdo-Dry Valleys). From these, 15 coccoid strains were chosen for more detailed investigation. They were characterized by morphological, physiological and chemotaxonomical properties. All isolates were Gram-positive, catalase-positive and nonmotile. Six strains showed red pigmentation and could be identified as members of the genera Micrococcus (M. roseus, M. agilis) or Deinococcus. In spite of their coccoid morphology, the remaining nine strains had to be associated with coryneform bacteria (Arthrobacter, Brevibacterium), because of their cell wall composition and G+C ratios. Most of the strains were psychrotrophic, but one strain was even obligately psychrophilic, with a temperature maximum below 20 degrees C. Red cocci had in vitro pH optima above 9.0 although they generally originated from acid samples. Most isolates showed a preference for sugar alcohols and organic acids, compounds which are commonly known to be released by lichens, molds and algae, the other components of the cryptoendolithic ecosystem. These properties indicate that our strains are autochthonous members of the natural Antarctic microbial population.

  5. A New Species of the Genus Kiwa (Decapoda: Anomura) from the Hydrothermal Vent of the Australia-Antarctic Ridge

    Science.gov (United States)

    Won, Y. J.; Lee, S. H.; Lee, W. K.

    2014-12-01

    Due to extreme weather conditions and remoteness to access, the great part of the Southern Ocean remains to be explored. Therefore, little is known about the Circum-Antarctic Ridge (CAR) system and its hydrothermal vent ecosystem underlying the Southern Ocean. We report the first discovery of a new deep-sea hydrothermal vent field and a new anomuran species from the Australia-Antarctic Ridge (AAR), the highest latitude (62°S; 158°E) explored in the Southern Ocean up to date. At this site, a new anomuran species which belongs to the genus Kiwa known as 'yeti crabs' was found. Morphologically, this species has characteristics of the genus Kiwa, including fifth pereopod inserted below sterna plastron, third sternite strongly produced anteriorly, and eyes extremely reduced. However, the new species differs from the other known species of Kiwa, K. hirsuta and K. puravida, showing relatively short rostrum and slender dactylus on second to fourth pereopods. Phylogenetic analysis using DNA sequences of eight genetic loci also supported the result of morphological analysis, confirming this species as a new Kiwa species, Kiwa n. sp. In addition, phylogenetic tree revealed the evolutionary relationship among the Kiwa species, presenting the Kiwa n. sp. as the sister species to K. puravida which inhabits the methane cold seep on the Pacific continental slope off Costa Rica. Considering the geography and the physicochemical environment, this unlikely result casts a mystery to be solved through further taxon sampling particularly from as-yet-unexplored vents and seeps. Discovery of the hydrothermal vent and Kiwa n. sp. from the AAR segment is significant because this site is located in the high latitude of the southern hemisphere and it is the region affected by the Antarctic Circumpolar Current (ACC). Future research on the relation of Kiwa n. sp. and the other Kiwa species affected by the ACC will provide an idea about the biogeography and the evolutionary connections of the

  6. Draft genome sequences of six neonatal meningitis-causing escherichia coli isolates (SP-4, SP-5, SP-13, SP-16, SP-46, and SP-65)

    Science.gov (United States)

    Neonatal meningitis Escherichia coli isolates (SP-4, SP-5, SP-13, SP-16, SP-46, and SP-65) were recovered from infants in the Netherlands from 1989 to 1997. Here, we report the draft genome sequences for these six E. coli isolates, which are currently being used to validate food safety processing te...

  7. Emerging spatial patterns in Antarctic prokaryotes.

    Science.gov (United States)

    Chong, Chun-Wie; Pearce, David A; Convey, Peter

    2015-01-01

    Recent advances in knowledge of patterns of biogeography in terrestrial eukaryotic organisms have led to a fundamental paradigm shift in understanding of the controls and history of life on land in Antarctica, and its interactions over the long term with the glaciological and geological processes that have shaped the continent. However, while it has long been recognized that the terrestrial ecosystems of Antarctica are dominated by microbes and their processes, knowledge of microbial diversity and distributions has lagged far behind that of the macroscopic eukaryote organisms. Increasing human contact with and activity in the continent is leading to risks of biological contamination and change in a region whose isolation has protected it for millions of years at least; these risks may be particularly acute for microbial communities which have, as yet, received scant recognition and attention. Even a matter apparently as straightforward as Protected Area designation in Antarctica requires robust biodiversity data which, in most parts of the continent, remain almost completely unavailable. A range of important contributing factors mean that it is now timely to reconsider the state of knowledge of Antarctic terrestrial prokaryotes. Rapid advances in molecular biological approaches are increasingly demonstrating that bacterial diversity in Antarctica may be far greater than previously thought, and that there is overlap in the environmental controls affecting both Antarctic prokaryotic and eukaryotic communities. Bacterial dispersal mechanisms and colonization patterns remain largely unaddressed, although evidence for regional evolutionary differentiation is rapidly accruing and, with this, there is increasing appreciation of patterns in regional bacterial biogeography in this large part of the globe. In this review, we set out to describe the state of knowledge of Antarctic prokaryote diversity patterns, drawing analogy with those of eukaryote groups where appropriate

  8. Bacterial diversity of autotrophic enriched cultures from remote, glacial Antarctic, Alpine and Andean aerosol, snow and soil samples

    Directory of Open Access Journals (Sweden)

    E. González-Toril

    2009-01-01

    Full Text Available Four different communities and one culture of autotrophic microbial assemblages were obtained by incubation of samples collected from high elevation snow in the Alps (Mt. Blanc area and the Andes (Nevado Illimani summit, Bolivia, from Antarctic aerosol (French station Dumont d'Urville and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas, in a minimal mineral (oligotrophic media. Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. Phylogenetic comparison with the currently available rDNA database allowed sequences belonging to Proteobacteria Alpha-, Beta- and Gamma-proteobacteria, Actinobacteria and Bacteroidetes phyla to be identified. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified and the marine Antarctic soil the poorest (only one. Snow samples from Col du Midi (Alps and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones. These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteriaclone. The only microorganism identified in the Antarctica soil (Brevundimonas sp. was also detected in the Antarctic aerosol. Most of the identified microorganisms had been detected previously in cold environments, marine sediments soils and rocks. Air current dispersal is the best model to explain the presence of very specific microorganisms, like those identified in this work, in environments very distant and very different from each other.

  9. A simulated Antarctic fast ice ecosystem

    Science.gov (United States)

    Arrigo, Kevin R.; Kremer, James N.; Sullivan, Cornelius W.

    1993-01-01

    A 2D numerical ecosystem model of Antarctic land fast ice is developed to elucidate the primary production with the Antarctic sea ice zone. The physical component employs atmospheric data to simulate congelation ice growth, initial brine entrapment, desalination, and nutrient flux. The biological component is based on the concept of a maximum temperature-dependent algal growth rate which is reduced by limitations imposed from insufficient light or nutrients, as well as suboptimal salinity. Preliminary simulations indicate that, during a bloom, microalgae are able to maintain their vertical position relative to the lower congelation ice margin and are not incorporated into the crystal matrix as the ice sheet thickens. It is inferred that land fast sea ice contains numerous microhabitats that are functionally distinct based upon the unique set of processes that control microalgal growth and accumulation within each.

  10. Subsurface Salts in Antarctic Dry Valley Soils

    Science.gov (United States)

    Englert, P.; Bishop, J. L.; Gibson, E. K.; Koeberl, C.

    2013-01-01

    The distribution of water-soluble ions, major and minor elements, and other parameters were examined to determine the extent and effects of chemical weathering on cold desert soils. Patterns at the study sites support theories of multiple salt forming processes, including marine aerosols and chemical weathering of mafic minerals. Periodic solar-mediated ionization of atmospheric nitrogen might also produce high nitrate concentrations found in older sediments. Chemical weathering, however, was the major contributor of salts in Antarctic Dry Valleys. The Antarctic Dry Valleys represent a unique analog for Mars, as they are extremely cold and dry desert environments. Similarities in the climate, surface geology, and chemical properties of the Dry Valleys to that of Mars imply the possible presence of these soil formation mechanisms on Mars, other planets and icy satellites.

  11. The signs of Antarctic ozone hole recovery.

    Science.gov (United States)

    Kuttippurath, Jayanarayanan; Nair, Prijitha J

    2017-04-03

    Absorption of solar radiation by stratospheric ozone affects atmospheric dynamics and chemistry, and sustains life on Earth by preventing harmful radiation from reaching the surface. Significant ozone losses due to increases in the abundances of ozone depleting substances (ODSs) were first observed in Antarctica in the 1980s. Losses deepened in following years but became nearly flat by around 2000, reflecting changes in global ODS emissions. Here we show robust evidence that Antarctic ozone has started to recover in both spring and summer, with a recovery signal identified in springtime ozone profile and total column measurements at 99% confidence for the first time. Continuing recovery is expected to impact the future climate of that region. Our results demonstrate that the Montreal Protocol has indeed begun to save the Antarctic ozone layer.

  12. Structural Uncertainty in Antarctic sea ice simulations

    Science.gov (United States)

    Schneider, D. P.

    2016-12-01

    The inability of the vast majority of historical climate model simulations to reproduce the observed increase in Antarctic sea ice has motivated many studies about the quality of the observational record, the role of natural variability versus forced changes, and the possibility of missing or inadequate forcings in the models (such as freshwater discharge from thinning ice shelves or an inadequate magnitude of stratospheric ozone depletion). In this presentation I will highlight another source of uncertainty that has received comparatively little attention: Structural uncertainty, that is, the systematic uncertainty in simulated sea ice trends that arises from model physics and mean-state biases. Using two large ensembles of experiments from the Community Earth System Model (CESM), I will show that the model is predisposed towards producing negative Antarctic sea ice trends during 1979-present, and that this outcome is not simply because the model's decadal variability is out-of-synch with that in nature. In the "Tropical Pacific Pacemaker" ensemble, in which observed tropical Pacific SST anomalies are prescribed, the model produces very realistic atmospheric circulation trends over the Southern Ocean, yet the sea ice trend is negative in every ensemble member. However, if the ensemble-mean trend (commonly interpreted as the forced response) is removed, some ensemble members show a sea ice increase that is very similar to the observed. While this results does confirm the important role of natural variability, it also suggests a strong bias in the forced response. I will discuss the reasons for this systematic bias and explore possible remedies. This an important problem to solve because projections of 21st -Century changes in the Antarctic climate system (including ice sheet surface mass balance changes and related changes in the sea level budget) have a strong dependence on the mean state of and changes in the Antarctic sea ice cover. This problem is not unique to

  13. A diagnostic study of Antarctic fog

    Science.gov (United States)

    Lazzara, Matthew A.

    2008-10-01

    The United States Antarctic Program (USAP) is the largest scientific research program in the Antarctic and requires a considerable aviation operation. Although fog is one of the top three forecast problems related to flights aborted due to weather, it is largely unstudied. The objective of this project is to gain an understanding of fog that affects McMurdo Station, Antarctica and its nearby airfields. This understanding is gained through analyses of surface based weather observations, satellite measurements and numerical weather prediction models. Multi-channel satellite observations indicate that most austral summer fog events are "advective" in nature. This is supported by weather observations from McMurdo Station and nearby airfields where fog occurs at moderate wind speeds, and primarily from the eastward direction. Analyses using both a back trajectory model and mesoscale numerical model are consistent with this finding. The primary source region for fog is found to be from the southeast over the Ross Ice Shelf (72% of the cases studied), while only a minority of cases (23%) reveals a secondary source of fog from the north along the Scott Coast with airflow influences from the East Antarctic Plateau. McMurdo experiences two fog seasons with a primary peak in January and a secondary peak in September. Fog events are often short lived---typically 1 to 3 hours, though some can last up to 30 hours. Fog occurrences over the last 30 years appear to be decreasing. Time series analysis between the observed fog variability and large-scale circulations (e.g., El Nino, Antarctic Oscillation) yielded no correlations, while there is only a limited relationship of fog occurrence to ice concentration in nearby Lewis Bay and McMurdo Sound. Fog is more likely to take place at the nearby airfields rather than at McMurdo Station, which is consistent with the advective nature of the fog.

  14. Antarctic isolation: immune and viral studies

    Science.gov (United States)

    Tingate, T. R.; Lugg, D. J.; Muller, H. K.; Stowe, R. P.; Pierson, D. L.

    1997-01-01

    Stressful environmental conditions are a major determinant of immune reactivity. This effect is pronounced in Australian National Antarctic Research Expedition populations exposed to prolonged periods of isolation in the Antarctic. Alterations of T cell function, including depression of cutaneous delayed-type hypersensitivity responses and a peak 48.9% reduction of T cell proliferation to the mitogen phytohaemagglutinin, were documented during a 9-month period of isolation. T cell dysfunction was mediated by changes within the peripheral blood mononuclear cell compartment, including a paradoxical atypical monocytosis associated with altered production of inflammatory cytokines. There was a striking reduction in the production by peripheral blood mononuclear cells of the predominant pro-inflammatory monokine TNF-alpha and changes were also detected in the production of IL-1, IL-2, IL-6, IL-1ra and IL-10. Prolonged Antarctic isolation is also associated with altered latent herpesvirus homeostasis, including increased herpesvirus shedding and expansion of the polyclonal latent Epstein-Barr virus-infected B cell population. These findings have important long-term health implications.

  15. EVA: Evryscopes for the Arctic and Antarctic

    Science.gov (United States)

    Richichi, A.; Law, N.; Tasuya, O.; Fors, O.; Dennihy, E.; Carlberg, R.; Tuthill, P.; Ashley, M.; Soonthornthum, B.

    2017-06-01

    We are planning to build Evryscopes for the Arctic and Antarctic (EVA), which will enable the first ultra-wide-field, high-cadence sky survey to be conducted from both Poles. The system is based on the successful Evryscope concept, already installed and operating since 2015 at Cerro Tololo in Chile with the following characteristics: robotic operation, 8,000 square degrees simultaneous sky coverage, 2-minute cadence, milli-mag level photometric accuracy, pipelined data processing for real-time analysis and full data storage for off-line analysis. The initial location proposed for EVA is the PEARL station on Ellesmere island; later also an antarctic location shall be selected. The science goals enabled by this unique combination of almost full-sky coverage and high temporal cadence are numerous, and include among others ground-breaking forays in the fields of exoplanets, stellar variability, asteroseismology, supernovae and other transient events. The EVA polar locations will enable uninterrupted observations lasting in principle over weeks and months. EVA will be fully robotic. We discuss the EVA science drivers and expected results, and present the logistics and the outline of the project which is expected to have first light in the winter of 2018. The cost envelope can be kept very competitive thanks to R&D already employed for the CTIO Evryscope, to our experience with both Arctic and Antarctic locations, and to the use of off-the-shelf components.

  16. Olfactory sex recognition investigated in Antarctic prions.

    Directory of Open Access Journals (Sweden)

    Francesco Bonadonna

    Full Text Available Chemical signals can yield information about an animal such as its identity, social status or sex. Such signals have rarely been considered in birds, but recent results have shown that chemical signals are actually used by different bird species to find food and to recognize their home and nest. This is particularly true in petrels whose olfactory anatomy is among the most developed in birds. Recently, we have demonstrated that Antarctic prions, Pachyptila desolata, are also able to recognize and follow the odour of their partner in a Y-maze.However, the experimental protocol left unclear whether this choice reflected an olfactory recognition of a particular individual (i.e. partner or a more general sex recognition mechanism. To test this second hypothesis, male and female birds' odours were presented simultaneously to 54 Antarctic prions in a Y-maze. Results showed random behaviour by the tested bird, independent of its sex or reproductive status. Present results do not support the possibility that Antarctic prions can distinguish the sex of a conspecific through its odour but indirectly support the hypothesis that they can distinguish individual odours.

  17. Balance of the West Antarctic Ice Sheet

    Science.gov (United States)

    2002-01-01

    For several decades, measurements of the West Antarctic Ice Sheet showed it to be retreating rapidly. But new data derived from satellite-borne radar sensors show the ice sheet to be growing. Changing Antarctic ice sheets remains an area of high scientific interest, particularly in light of recent global warming concerns. These new findings are significant because scientists estimate that sea level would rise 5-6 meters (16-20 feet) if the ice sheet collapsed into the sea. Do these new measurements signal the end of the ice sheet's 10,000-year retreat? Or, are these new satellite data simply much more accurate than the sparse ice core and surface measurements that produced the previous estimates? Another possibility is that the ice accumulation may simply indicate that the ice sheet naturally expands and retreats in regular cycles. Cryologists will grapple with these questions, and many others, as they examine the new data. The image above depicts the region of West Antarctica where scientists measured ice speed. The fast-moving central ice streams are shown in red. Slower tributaries feeding the ice streams are shown in blue. Green areas depict slow-moving, stable areas. Thick black lines depict the areas that collect snowfall to feed their respective ice streams. Reference: Ian Joughin and Slawek Tulaczyk Science Jan 18 2002: 476-480. Image courtesy RADARSAT Antarctic Mapping Project

  18. Statistical optimization of beta-carotene production by Arthrobacter agilis A17 using response surface methodology and Box-Behnken design

    Science.gov (United States)

    Özdal, Murat; Özdal, Özlem Gür; Gürkök, Sümeyra

    2017-04-01

    β-carotene is a commercially important natural pigment and has been widely applied in the medicine, pharmaceutical, food, feed and cosmetic industries. The current study aimed to investigate the usability of molasses for β-carotene production by Arthrobacter agilis A17 (KP318146) and to optimize the production process. Box-Behnken Design of Response Surface Methodology was used to determine the optimum levels and the interactions of three independent variables namely molasses, yeast extract and KH2PO4 at three different levels. β-carotene yield in optimized medium containing 70 g/l molasses, 25 g/l yeast extract and 0.96 g/l KH2PO4, reached up to 100 mg/l, which is approximately 2.5-fold higher than the yield, obtained from control cultivation. A remarkable β-carotene production on inexpensive carbon source was achieved with the use of statistical optimization.

  19. Reaching for the Horizon: Enabling 21st Century Antarctic Science

    Science.gov (United States)

    Rogan-Finnemore, M.; Kennicutt, M. C., II; Kim, Y.

    2015-12-01

    The Council of Managers of National Antarctic Programs' (COMNAP) Antarctic Roadmap Challenges(ARC) project translated the 80 highest priority Antarctic and Southern Ocean scientific questionsidentified by the community via the SCAR Antarctic Science Horizon Scan into the highest prioritytechnological, access, infrastructure and logistics needs to enable the necessary research to answer thequestions. A workshop assembled expert and experienced Antarctic scientists and National AntarcticProgram operators from around the globe to discern the highest priority technological needs includingthe current status of development and availability, where the technologies will be utilized in the Antarctic area, at what temporal scales and frequencies the technologies will be employed,and how broadly applicable the technologies are for answering the highest priority scientific questions.Secondly the logistics, access, and infrastructure requirements were defined that are necessary todeliver the science in terms of feasibility including cost and benefit as determined by expected scientific return on investment. Finally, based on consideration of the science objectives and the mix oftechnologies implications for configuring National Antarctic Program logistics capabilities andinfrastructure architecture over the next 20 years were determined. In particular those elements thatwere either of a complexity, requiring long term investments to achieve and/or having an associated cost that realistically can only (or best) be achieved by international coordination, planning and partnerships were identified. Major trends (changes) in logistics, access, and infrastructure requirements were identified that allow for long-term strategic alignment of international capabilities, resources and capacity. The outcomes of this project will be reported.

  20. Antarctic bacteria inhibit growth of foodborne microorganisms at low temperatures.

    NARCIS (Netherlands)

    O'Brien, A.C.; Sharp, R.; Russell, N.J.; Roller, S.

    2004-01-01

    The aim of this study was to identify Antarctic microorganisms with the ability to produce cold-active antimicrobial compounds with potential for use in chilled food preservation. Colonies (4496) were isolated from 12 Antarctic soil samples and tested against Listeria innocua, Pseudomonas fragi and

  1. Biological studies in the Antarctic waters: A review

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.

    stream_size 12 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_407.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_407.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  2. Separate origins of ice-binding proteins in antarctic chlamydomonas species.

    Science.gov (United States)

    Raymond, James A; Morgan-Kiss, Rachael

    2013-01-01

    The green alga Chlamydomonas raudensis is an important primary producer in a number of ice-covered lakes and ponds in Antarctica. A C. raudensis isolate (UWO241) from Lake Bonney in the McMurdo Dry Valleys, like many other Antarctic algae, was found to secrete ice-binding proteins (IBPs), which appear to be essential for survival in icy environments. The IBPs of several Antarctic algae (diatoms, a prymesiophyte, and a prasinophyte) are similar to each other (here designated as type I IBPs) and have been proposed to have bacterial origins. Other IBPs (type II IBPs) that bear no resemblance to type I IBPs, have been found in the Antarctic Chlamydomonas sp. CCMP681, a putative snow alga, raising the possibility that chlamydomonad IBPs developed separately from the IBPs of other algae. To test this idea, we obtained the IBP sequences of C. raudensis UWO241 by sequencing the transcriptome. A large number of transcripts revealed no sequences resembling type II IBPs. Instead, many isoforms resembling type I IBPs were found, and these most closely matched a hypothetical protein from the bacterium Stigmatella aurantiaca. The sequences were confirmed to encode IBPs by the activity of a recombinant protein and by the matching of predicted and observed isoelectric points and molecular weights. Furthermore, a mesophilic sister species, C. raudensis SAG49.72, showed no ice-binding activity or PCR products from UWO241 IBP primers. These results confirm that algal IBPs are required for survival in icy habitats and demonstrate that they have diverse origins that are unrelated to the taxonomic positions of the algae. Last, we show that the C. raudensis UWO241 IBPs can change the structure of ice in a way that could increase the survivability of cells trapped in the ice.

  3. Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years

    Science.gov (United States)

    Gardner, Alex S.; Moholdt, Geir; Scambos, Ted; Fahnstock, Mark; Ligtenberg, Stefan; van den Broeke, Michiel; Nilsson, Johan

    2018-02-01

    Ice discharge from large ice sheets plays a direct role in determining rates of sea-level rise. We map present-day Antarctic-wide surface velocities using Landsat 7 and 8 imagery spanning 2013-2015 and compare to earlier estimates derived from synthetic aperture radar, revealing heterogeneous changes in ice flow since ˜ 2008. The new mapping provides complete coastal and inland coverage of ice velocity north of 82.4° S with a mean error of the daylight period. Using an optimized flux gate, ice discharge from Antarctica is 1929 ± 40 Gigatons per year (Gt yr-1) in 2015, an increase of 36 ± 15 Gt yr-1 from the time of the radar mapping. Flow accelerations across the grounding lines of West Antarctica's Amundsen Sea Embayment, Getz Ice Shelf and Marguerite Bay on the western Antarctic Peninsula, account for 88 % of this increase. In contrast, glaciers draining the East Antarctic Ice Sheet have been remarkably constant over the period of observation. Including modeled rates of snow accumulation and basal melt, the Antarctic ice sheet lost ice at an average rate of 183 ± 94 Gt yr-1 between 2008 and 2015. The modest increase in ice discharge over the past 7 years is contrasted by high rates of ice sheet mass loss and distinct spatial patters of elevation lowering. The West Antarctic Ice Sheet is experiencing high rates of mass loss and displays distinct patterns of elevation lowering that point to a dynamic imbalance. We find modest increase in ice discharge over the past 7 years, which suggests that the recent pattern of mass loss in Antarctica is part of a longer-term phase of enhanced glacier flow initiated in the decades leading up to the first continent-wide radar mapping of ice flow.

  4. Ocean processes at the Antarctic continental slope.

    Science.gov (United States)

    Heywood, Karen J; Schmidtko, Sunke; Heuzé, Céline; Kaiser, Jan; Jickells, Timothy D; Queste, Bastien Y; Stevens, David P; Wadley, Martin; Thompson, Andrew F; Fielding, Sophie; Guihen, Damien; Creed, Elizabeth; Ridley, Jeff K; Smith, Walker

    2014-07-13

    The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean-atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An iron-cycling model embedded in an eddy-permitting ocean model reveals the importance of sedimentary iron in fertilizing parts of the Southern Ocean. Ocean gliders play a key role in improving our ability to observe and understand these small-scale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the Ocean (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the Antarctic Peninsula in unprecedented temporal and spatial detail. The glider data resolve small-scale exchange processes across the shelf-break front (the Antarctic Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of ocean gliders to play a key role in a future multi-disciplinary Southern Ocean observing system.

  5. Emerging spatial patterns in Antarctic prokaryotes

    Directory of Open Access Journals (Sweden)

    Chun Wie eChong

    2015-09-01

    Full Text Available Recent advances in knowledge of patterns of biogeography in terrestrial eukaryotic organisms have led to a fundamental paradigm shift in understanding of the controls and history of life on land in Antarctica, and its interactions over the long term with the glaciological and geological processes that have shaped the continent. However, while it has long been recognized that the terrestrial ecosystems of Antarctica are dominated by microbes and their processes, knowledge of microbial diversity and distributions has lagged far behind that of the macroscopic eukaryote organisms. Increasing human contact with and activity in the continent is leading to risks of biological contamination and change in a region whose isolation has protected it for millions of years at least; these risks may be particularly acute for microbial communities which have, as yet, received scant recognition and attention. Even a matter apparently as straightforward as Protected Area designation in Antarctica requires robust biodiversity data which, in most parts of the continent, remain almost completely unavailable. A range of important contributing factors mean that it is now timely to reconsider the state of knowledge of Antarctic terrestrial prokaryotes. Rapid advances in molecular biological approaches are increasingly demonstrating that bacterial diversity in Antarctica may be far greater than previously thought, and that there is overlap in the environmental controls affecting both Antarctic prokaryotic and eukaryotic communities. Bacterial dispersal mechanisms and colonization patterns remain largely unaddressed, although evidence for regional evolutionary differentiation is rapidly accruing and, with this, there is increasing appreciation of patterns in regional bacterial biogeography in this large part of the globe. In this review, we set out to describe the state of knowledge of Antarctic prokaryote diversity patterns, drawing analogy with those of eukaryote

  6. The late Cainozoic East Antarctic ice sheet

    International Nuclear Information System (INIS)

    Colhoun, E.A.

    1999-01-01

    A review, mainly of East Antarctic late Cainozoic (post 40 Ma) geological and geomorphological evidence, supports the hypothesis of the continuous presence of an ice sheet, of about the present size, since the late Miocene. Evidence is presented and the view advanced that, during the late Wisconsin maximum of isotope stage 2, ice was not nearly as thick or extensive over the continental shelf as required by the model of 'maximum' Antarctic glaciation. Some of the factors influencing the contribution of Antarctica to post-glacial sea-level rise are discussed. It is considered that Antarctica's contribution was probably considerably less than previously estimated. The dating of marine and freshwater sequences in the Vestfold and Bunger Hills is consistent with deglaciation around the Pleistocene Holocene boundary, after the Late Wisconsin maximum. A date of ∼25 ka BP from permafrost in the Larsemann Hills means that either the Larsemann Hills were not glaciated during the Late Wisconsin or the ice failed to erode much of the permafrost surface. The degree of weathering of rock and glacial drifts in the Vestfold, Larsemann and Bunger Hills suggests a long time for formation, perhaps considerably longer than indicated by the dated marine and freshwater sediment sequences. Cosmogenic isotope dating in the Vestfold Hills has provided equivocal ages for deglaciation. While the results could indicate deglaciation before 80 ka BP, they do not confirm such early deglaciation. If the ice cover was thin and failed to remove the previous rock exposure profile, then the assays could predate the last ice advance. Weathered iron crust fragments in the till suggest little erosion. The raised beaches of the oases are Holocene. Assuming they have been produced by post Late Wisconsin isostatic uplift and by the Holocene transgression, calculations show that the Antarctic continental ice sheet could not have been more than ∼500 m thicker in the inner shelf-coastal zone. The

  7. Portable Habitat for Antarctic Scientific Research (PHASR)

    Science.gov (United States)

    Griswold, Samantha S.

    1992-01-01

    The Portable Habitat for Antarctic Scientific Research, PHASR, is designed as a versatile, general purpose habitat system that addresses the problem of functional space and environmental soundness in a partially fabric-covered shelter. PHASR is used for remote field site applications that can be quickly deployed. PHASR will also provide four scientists with a comfortable and efficient use of interior space. PHASR is a NASA/USRA Advanced Design Program project conducted at the University of Houston College of Architecture, Sasadawa International Center for Space Architecture (SICSA). This report is prepared for NASA/USRA.

  8. When will the Antarctic Ozone Hole Recover?

    Science.gov (United States)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Steve

    2006-01-01

    The Antarctic ozone hole develops each year and culminates by early Spring. Antarctic ozone values have been monitored since 1979 using satellite observations from the .TOMS instrument. The severity of the hole has been assessed from TOMS using the minimum total ozone value from the October monthly mean (depth of the hole) and by calculating the average size during the September-October period. Ozone is mainly destroyed by halogen catalytic cycles, and these losses are modulated by temperature variations in the collar of the polar lower stratospheric vortex. In this presentation, we show the relationships of halogens and temperature to, both the size and depth of the hole. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Using projections of halogen levels combined with age-of-air estimates, we find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. The ozone hole will begin to show first signs of recovery in about 2023, and the hole will fully recover to pre-1980 levels in approximately 2070. This 2070 recovery is 20 years later than recent projections.

  9. Recovery of the Antarctic Ozone Hole

    Science.gov (United States)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Steve; Schauffler, Sue; Stolarski, Richard S.; Douglass, Anne R.; Pawson, Steven; Nielsen, J. Eric

    2006-01-01

    The Antarctic ozone hole develops each year and culminates by early Spring. Antarctic ozone values have been monitored since 1979 using satellite observations from the TOMS and OMI instruments. The severity of the hole has been assessed using the minimum total ozone value from the October monthly mean (depth of the hole), the average size during the September-October period, and the ozone mass deficit. Ozone is mainly destroyed by halogen catalytic cycles, and these losses are modulated by temperature variations in the collar of the polar lower stratospheric vortex. In this presentation, we show the relationships of halogens and temperature to both the size and depth of the hole. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. We use two methods to estimate ozone hole recovery. First, we use projections of halogen levels combined with age-of-air estimates in a parametric model. Second, we use a coupled chemistry climate model to assess recovery. We find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. Furthermore, full recovery to 1980 levels will not occur until approximately 2068. We will also show some error estimates of these dates and the impact of climate change on the recovery.

  10. CHAMP Magnetic Anomalies of the Antarctic Crust

    Science.gov (United States)

    Kim, Hyung Rae; Gaya-Pique, Luis R.; vonFrese, Ralph R. B.; Taylor, Patrick T.; Kim, Jeong Woo

    2003-01-01

    Regional magnetic signals of the crust are strongly masked by the core field and its secular variations components and hence difficult to isolate in the satellite measurements. In particular, the un-modeled effects of the strong auroral external fields and the complicated- behavior of the core field near the geomagnetic poles conspire to greatly reduce the crustal magnetic signal-to-noise ratio in the polar regions relative to the rest of the Earth. We can, however, use spectral correlation theory to filter the static lithospheric and core field components from the dynamic external field effects. To help isolate regional lithospheric from core field components, the correlations between CHAMP magnetic anomalies and the pseudo magnetic effects inferred from gravity-derived crustal thickness variations can also be exploited.. Employing these procedures, we processed the CHAMP magnetic observations for an improved magnetic anomaly map of the Antarctic crust. Relative to the much higher altitude Orsted and noisier Magsat observations, the CHAMP magnetic anomalies at 400 km altitude reveal new details on the effects of intracrustal magnetic features and crustal thickness variations of the Antarctic.

  11. Mass balance of the Antarctic ice sheet.

    Science.gov (United States)

    Wingham, D J; Shepherd, A; Muir, A; Marshall, G J

    2006-07-15

    The Antarctic contribution to sea-level rise has long been uncertain. While regional variability in ice dynamics has been revealed, a picture of mass changes throughout the continental ice sheet is lacking. Here, we use satellite radar altimetry to measure the elevation change of 72% of the grounded ice sheet during the period 1992-2003. Depending on the density of the snow giving rise to the observed elevation fluctuations, the ice sheet mass trend falls in the range -5-+85Gtyr-1. We find that data from climate model reanalyses are not able to characterise the contemporary snowfall fluctuation with useful accuracy and our best estimate of the overall mass trend-growth of 27+/-29Gtyr-1-is based on an assessment of the expected snowfall variability. Mass gains from accumulating snow, particularly on the Antarctic Peninsula and within East Antarctica, exceed the ice dynamic mass loss from West Antarctica. The result exacerbates the difficulty of explaining twentieth century sea-level rise.

  12. Extremophiles in an Antarctic Marine Ecosystem

    Directory of Open Access Journals (Sweden)

    Iain Dickinson

    2016-01-01

    Full Text Available Recent attempts to explore marine microbial diversity and the global marine microbiome have indicated a large proportion of previously unknown diversity. However, sequencing alone does not tell the whole story, as it relies heavily upon information that is already contained within sequence databases. In addition, microorganisms have been shown to present small-to-large scale biogeographical patterns worldwide, potentially making regional combinations of selection pressures unique. Here, we focus on the extremophile community in the boundary region located between the Polar Front and the Southern Antarctic Circumpolar Current in the Southern Ocean, to explore the potential of metagenomic approaches as a tool for bioprospecting in the search for novel functional activity based on targeted sampling efforts. We assessed the microbial composition and diversity from a region north of the current limit for winter sea ice, north of the Southern Antarctic Circumpolar Front (SACCF but south of the Polar Front. Although, most of the more frequently encountered sequences  were derived from common marine microorganisms, within these dominant groups, we found a proportion of genes related to secondary metabolism of potential interest in bioprospecting. Extremophiles were rare by comparison but belonged to a range of genera. Hence, they represented interesting targets from which to identify rare or novel functions. Ultimately, future shifts in environmental conditions favoring more cosmopolitan groups could have an unpredictable effect on microbial diversity and function in the Southern Ocean, perhaps excluding the rarer extremophiles.

  13. Microbial biomass and basal respiration in Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

    Science.gov (United States)

    Abakumov, E.; Mukhametova, N.

    2014-03-01

    Antarctica is the unique place for pedological investigations. Soils of Antarctica have been studied intensively during the last century. Antarctic logistic provides the possibility to scientists access the terrestrial landscapes mainly in the places of polar stations. That is why the main and most detailed pedological investigations were conducted in Mc Murdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann hills and Schirmacher Oasis. Investigations were conducted during the 53rd and 55th Russian Antarctic expeditions on the base of soil pits and samples collected in Sub-Antarctic and Antarctic regions. Soils of diverse Antarctic landscapes were studied with aim to assess the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. The investigation conducted shows that soils of Antarctic are quite different in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod) organo-mineral horizons as well as the upper organic layer. The most developed organic layers were revealed in peat soils of King-George Island, where its thickness reach even 80 cm. These soils as well as soils under guano are characterized by the highest amount of total organic carbon (TOC) 7.22-33.70%. Coastal and continental soils of Antarctic are presented by less developed Leptosols, Gleysols, Regolith and rare Ornhitosol with TOC levels about 0.37-4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones which can be interpreted as result of higher amounts of fresh organic remnants in organic and organo-mineral horizons. Also the soils of King-George island have higher portion of microbial biomass (max 1.54 mg g-1) than coastal (max 0.26 mg g-1) and continental (max 0.22 mg g-1) Antarctic soils. Sub-Antarctic soils mainly differ from Antarctic ones in increased organic layers thickness and total organic carbon content

  14. Adjustment of pigment composition in Desmarestia (Desmarestiaceae species along a sub-Antarctic to Antarctic latitudinal gradient

    Directory of Open Access Journals (Sweden)

    Andrés Mansilla

    2016-08-01

    Full Text Available Photosynthesis at high latitudes demands efficient strategies of light utilization to maintain algal fitness and performance. The fitness, and physiological adaptation, of a plant or algae species depends in part on the abundance and efficiency of the pigments it can produce to utilize the light resource from its environment. We quantified pigment composition and concentration in six species of the brown macroalgal genus Desmarestia, collected from sub-Antarctic sites (Strait of Magellan, Beagle Channel–Cape Horn Province and sites on the Antarctic Peninsula and adjacent islands. Sub-Antarctic Desmarestia species exhibited lower concentrations of chlorophyll a, chlorophyll c and fucoxanthin than endemic Antarctic species. Antarctic samples of D. menziesii and D. antarctica collected along a decreasing latitudinal gradient showed spatial and interspecific differences in light-harvesting pigment composition. Our results suggest distinct physiological adjustments in Desmarestia species in response to heterogeneous abiotic environmental conditions. The marine sub-Antarctic and Antarctic ecosystems are characterized by harsh environments (e.g., extreme irradiance, photoperiod, temperature, salinity to which the physiology of macroalgal species must adapt.

  15. Biodegradation of 4-bromophenol by Arthrobacter chlorophenolicus A6 in batch shake flasks and in a continuously operated packed bed reactor.

    Science.gov (United States)

    Sahoo, Naresh Kumar; Pakshirajan, Kannan; Ghosh, Pranab Kumar

    2014-04-01

    The present study investigated growth and biodegradation of 4-bromophenol (4-BP) by Arthrobacter chlorophenolicus A6 in batch shake flasks as well as in a continuously operated packed bed reactor (PBR). Batch growth kinetics of A. chlorophenolicus A6 in presence of 4-BP followed substrate inhibition kinetics with the estimated biokinetic parameters value of μ max = 0.246 h(-1), K i = 111 mg L(-1), K s  = 30.77 mg L(-1) and K = 100 mg L(-1). In addition, variations in the observed and theoretical biomass yield coefficient and maintenance energy of the culture were investigated at different initial 4-BP concentration. Results indicates that the toxicity tolerance and the biomass yield of A. chlorophenolicus A6 towards 4-BP was found to be poor as the organism utilized the substrate mainly for its metabolic maintenance energy. Further, 4-BP biodegradation performance by the microorganism was evaluated in a continuously operated PBR by varying the influent concentration and hydraulic retention time in the ranges 400-1,200 mg L(-1) and 24-7.5 h, respectively. Complete removal of 4-BP was achieved in the PBR up to a loading rate of 2,276 mg L(-1) day(-1).

  16. 2-Keto-D-Gluconate-Yielding Membrane-Bound D-Glucose Dehydrogenase from Arthrobacter globiformis C224: Purification and Characterization

    Directory of Open Access Journals (Sweden)

    Qing Xue

    2015-01-01

    Full Text Available Glucose dehydrogenase (GlcDH is the rate-limiting catalyst for microbial conversion of glucose to the important organic acid 2-ketogluconic acid (2KGlcA. In this study, a D-glucose dehydrogenase was purified from the industrial 2KGlcA producer Arthrobacter globiformis C224. After four purification steps, the GlcDH was successfully purified over 180 folds and specific activity of 88.1 U/mg. A single protein band of 87 kDa was detected by SDS-PAGE. The purified GlcDH had the broad substrate specificity with the Km values for D-glucose, D-xylose, D-galactose and maltose of 0.21 mM, 0.34 mM, 0.46 mM and 0.59 mM, respectively. The kinetic studies proved that A. globiformis GlcDH followed the ping-pong kinetic mechanism. The GlcDH showed an optimum catalytic activity at pH 5.0 and 45 °C with the stable activity at temperature of 20–40 °C and pH of 6.0–7.0. Organic solvents, metal ions or EDTA could significantly influence the GlcDH activity to different degrees.

  17. Toxicity screening of soils from different mine areas—A contribution to track the sensitivity and variability of Arthrobacter globiformis assay

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Catarina R., E-mail: crmarques@ua.pt [Departamento de Biologia and CESAM (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Caetano, Ana L. [Departamento de Biologia and CESAM (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Haller, Andreas [ECT Oekotoxikologie GmbH, Böttgerstraße 2–14, D-65439 Flörsheim a. M. (Germany); Gonçalves, Fernando [Departamento de Biologia and CESAM (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Pereira, Ruth [Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto (Portugal); Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas 289, P 4050-123 Porto (Portugal); Römbke, Jörg [ECT Oekotoxikologie GmbH, Böttgerstraße 2–14, D-65439 Flörsheim a. M. (Germany)

    2014-06-01

    Highlights: • The assay gave rapid and feasible discrimination of toxic soils to A. globiformis. • Sensitive and low variability response to soils from different regions. • Soil properties may interfere with metal toxicity and fluorescence measurements. • Proposal of a toxicity threshold for the contact assay regarding soils. • A. globiformis assay should be included in the Tier I of risk assessment frameworks. - Abstract: This study used the Arthrobacter globiformis solid-contact test for assessing the quality of soils collected in areas subjected to past and present mine activities in Europe (uranium mine, Portugal) and North Africa (phosphogypsum pile, Tunisia; iron mine, Morocco). As to discriminate the influence of soils natural variability from the effect of contaminants, toxicity thresholds were derived for this test, based on the dataset of each study area. Furthermore, the test sensitivity and variability was also evaluated. As a result, soils that inhibited A. globiformis dehydrogenase activity above 45% or 50% relatively to the control, were considered to be toxic. Despite the soil metal content determined, the properties of soils seemed to influence dehydrogenase activity. Overall, the contact test provided a coherent outcome comparing to other more time-consuming and effort-demanding ecotoxicological assays. Our results strengthened the feasibility and ecological relevance of this assay, which variability was quite reduced hence suggesting its potential integration within the test battery of tier 1 of soil risk assessment schemes.

  18. Photosynthesis in a sub-Antarctic shore-zone lichen

    NARCIS (Netherlands)

    Smith, V.; Gremmen, N.J.M.

    2001-01-01

    Photosynthetic responses to moisture, light, temperature, salinity and inorganic nitrogen fertilization are reported for a shore-zone lichen Turgidiusculum complicatulum (formerly Mastodia tesselata), a possible recent introduction to sub-Antarctic Marion Island. Optimum moisture contents for net

  19. Radarsat Antarctic Mapping Project Digital Elevation Model, Version 2

    Data.gov (United States)

    National Aeronautics and Space Administration — The high-resolution Radarsat Antarctic Mapping Project (RAMP) Digital Elevation Model (DEM) combines topographic data from a variety of sources to provide consistent...

  20. Historical Arctic and Antarctic Surface Observational Data, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This product consists of meteorological data from 105 Arctic weather stations and 137 Antarctic stations, extracted from the National Climatic Data Center (NCDC)'s...

  1. Antarctic Active Subglacial Lake Inventory from ICESat Altimetry, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains lake boundaries, volume changes, and gridded elevations for 124 active subglacial lakes beneath the Antarctic ice sheet. Lakes were identified...

  2. Antarctic stratospheric ozone and seasonal predictability over southern Africa

    CSIR Research Space (South Africa)

    Engelbrecht, FA

    2015-09-01

    Full Text Available The impact of time-varying Antarctic stratospheric ozone on southern African summer climate variability is explored through atmospheric global circulation model (AGCM) sensitivity experiments. A control experiment following the design...

  3. Antarctic Glacial Chronology: New Constraints from Surface Exposure Dating

    National Research Council Canada - National Science Library

    Ackert, Robert

    2000-01-01

    .... New He-3 production rates are determined from a 125 ka lava flow. Measurements of inherited He-3/He-4 in two common Antarctic lithologies allow measurement of exposure ages < 6000 years. At Mt...

  4. University of Wisconsin Antarctic Soils Database, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The University of Wisconsin Antarctic Soils Database contains data collected by Dr. James G. Bockheim and his colleagues from 1975 through 1987. Data include site...

  5. Climate Prediction Center(CPC)Monthly Antarctic Oscillation Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Antarctic Oscillation (AAO) is a leading teleconnection pattern in the Southern Hemisphere circulation. It is calculated as the first Empirical Orthogonal...

  6. Climate Prediction Center (CPC) Daily Antarctic Oscillation Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Antarctic Oscillation (AAO) is a leading teleconnection pattern in the Southern Hemisphere circulation. It is calculated as the first Empirical Orthogonal...

  7. ExaSP2

    Energy Technology Data Exchange (ETDEWEB)

    2017-09-08

    ExaSP2 is a reference implementation of typical linear algebra algorithms and workloads for a quantum molecular dynamics (QMD) electronic structure code. The algorithm is based on a recursive second-order Fermi-Operator expansion method (SP2) and is tailored for density functional based tight-binding calculations of material systems.

  8. Morphogenesis of Antarctic Paleosols: Martian Analogue

    Science.gov (United States)

    Mahaney, W. C.; Dohm, J. M.; Baker, V. R.; Newsom, Horton E.; Malloch, D.; Hancock, R. G. V.; Campbell, Iain; Sheppard, D.; Milner, M. W.

    2001-11-01

    Samples of horizons in paleosols from the Quartermain Mountains of the Antarctic Dry Valleys (Aztec and New Mountain areas) were analyzed for their physical characteristics, mineralogy, chemical composition, and microbiology to determine the accumulation and movement of salts and other soluble constituents and the presence/absence of microbial populations. Salt concentrations are of special interest because they are considered to be a function of age, derived over time, in part from nearby oceanic and high-altitude atmospheric sources. The chemical composition of ancient Miocene-age paleosols in these areas is the direct result of the deposition and weathering of airborne-influxed salts and other materials, as well as the weathering of till derived principally from local dolerite and sandstone outcrops. Paleosols nearer the coast have greater contents of Cl, whereas near the inland ice sheet, nitrogen tends to increase on a relative basis. The accumulation and vertical distribution of salts and other soluble chemical elements indicate relative amounts of movement in the profile over long periods of time, in the order of several million years. Four of the six selected subsamples from paleosol horizons in two ancient soil profiles contained nil concentrations of bacteria and fungi. However, two horizons at depths of between 3 and 8 cm, in two profiles, yielded several colonies of the fungi Beauveria bassiana and Penicillium brevicompactum, indicating very minor input of organic carbon. Beauveria bassiana is often reported in association with insects and is used commercially for the biological control of some insect pests. Penicillium species are commonly isolated from Arctic, temperate, and tropical soils and are known to utilize a wide variety of organic carbon and nitrogen compounds. The cold, dry soils of the Antarctic bear a close resemblance to various present and past martian environments where similar weathering could occur and possible microbial populations

  9. Functional ecology of an Antarctic Dry Valley

    Science.gov (United States)

    Chan, Yuki; Van Nostrand, Joy D.; Zhou, Jizhong; Pointing, Stephen B.

    2013-01-01

    The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are critically at risk from climate change. The terrestrial landscape is dominated by oligotrophic mineral soils and extensive exposed rocky surfaces where biota are largely restricted to microbial communities, although their ability to perform the majority of geobiological processes has remained largely uncharacterized. Here, we identified functional traits that drive microbial survival and community assembly, using a metagenomic approach with GeoChip-based functional gene arrays to establish metabolic capabilities in communities inhabiting soil and rock surface niches in McKelvey Valley. Major pathways in primary metabolism were identified, indicating significant plasticity in autotrophic, heterotrophic, and diazotrophic strategies supporting microbial communities. This represents a major advance beyond biodiversity surveys in that we have now identified how putative functional ecology drives microbial community assembly. Significant differences were apparent between open soil, hypolithic, chasmoendolithic, and cryptoendolithic communities. A suite of previously unappreciated Antarctic microbial stress response pathways, thermal, osmotic, and nutrient limitation responses were identified and related to environmental stressors, offering tangible clues to the mechanisms behind the enduring success of microorganisms in this seemingly inhospitable terrain. Rocky substrates exposed to larger fluctuations in environmental stress supported greater functional diversity in stress-response pathways than soils. Soils comprised a unique reservoir of genes involved in transformation of organic hydrocarbons and lignin-like degradative pathways. This has major implications for the evolutionary origin of the organisms, turnover of recalcitrant substrates in Antarctic soils, and predicting future responses to anthropogenic pollution. PMID:23671121

  10. Fundamental differences between Arctic and Antarctic ozone depletion

    OpenAIRE

    Solomon, Susan; Haskins, Jessica; Ivy, Diane J.; Min, Flora

    2014-01-01

    Fundamental differences in observed ozone depletion between the Arctic and the Antarctic are shown, clarifying distinctions between both average and extreme ozone decreases in the two hemispheres. Balloon-borne and satellite measurements in the heart of the ozone layer near 18−24 km altitude show that extreme ozone decreases often observed in the Antarctic ozone hole region have not yet been measured in the Arctic in any year, including the unusually cold Arctic spring of 2011. The data provi...

  11. Transcriptomics and comparative analysis of three antarctic notothenioid fishes.

    Directory of Open Access Journals (Sweden)

    Seung Chul Shin

    Full Text Available For the past 10 to 13 million years, Antarctic notothenioid fish have undergone extraordinary periods of evolution and have adapted to a cold and highly oxygenated Antarctic marine environment. While these species are considered an attractive model with which to study physiology and evolutionary adaptation, they are poorly characterized at the molecular level, and sequence information is lacking. The transcriptomes of the Antarctic fishes Notothenia coriiceps, Chaenocephalus aceratus, and Pleuragramma antarcticum were obtained by 454 FLX Titanium sequencing of a normalized cDNA library. More than 1,900,000 reads were assembled in a total of 71,539 contigs. Overall, 40% of the contigs were annotated based on similarity to known protein or nucleotide sequences, and more than 50% of the predicted transcripts were validated as full-length or putative full-length cDNAs. These three Antarctic fishes shared 663 genes expressed in the brain and 1,557 genes expressed in the liver. In addition, these cold-adapted fish expressed more Ub-conjugated proteins compared to temperate fish; Ub-conjugated proteins are involved in maintaining proteins in their native state in the cold and thermally stable Antarctic environments. Our transcriptome analysis of Antarctic notothenioid fish provides an archive for future studies in molecular mechanisms of fundamental genetic questions, and can be used in evolution studies comparing other fish.

  12. Parasites of the Antarctic toothfish (Dissostichus mawsoni Norman, 1937 (Perciformes, Nototheniidae in the Pacific sector of the Antarctic

    Directory of Open Access Journals (Sweden)

    Ilya I. Gordeev

    2016-06-01

    Full Text Available The Antarctic toothfish (Dissostichus mawsoni Norman, 1937 is one of the main target species of commercial fisheries in the Antarctic. It is an endemic and is found along the shelf of Antarctica, as well as on the slopes of seamounts, underwater elevations and islands in the sub-Antarctic. It feeds on a variety of fish and cephalopods and can be an intermediate/paratenic host of some helminthes, whose final hosts are whales, seals, large rays and sharks. This article presents new data on toothfish infection in the Pacific sector of the Antarctic. Specimens were examined during commercial longline fishing in the Ross Sea and the Amundsen Sea in January–February 2013. Fourteen species of parasites were found using standard parasitological methods and genetic analysis.

  13. A long term strategy for Antarctic tourism : The key to decision making within the Antarctic Treaty System?

    NARCIS (Netherlands)

    Bastmeijer, C.J.; Maher, P.; Stewart, E.; Lück, M.

    2011-01-01

    The fast increase of Antarctic tourism raises various management questions. Questions relating to the safety of tourists, questions regarding the interaction between science and tourism and questions relating to direct, indirect or cumulative affects on Antarctica's environment and wilderness

  14. Development of a regional glycerol dialkyl glycerol tetraether (GDGT)-temperature calibration for Antarctic and sub-Antarctic lakes

    Science.gov (United States)

    Foster, Louise C.; Pearson, Emma J.; Juggins, Steve; Hodgson, Dominic A.; Saunders, Krystyna M.; Verleyen, Elie; Roberts, Stephen J.

    2016-01-01

    A regional network of quantitative reconstructions of past climate variability is required to test climate models. In recent studies, temperature calibration models based on the relative abundances of sedimentary glycerol dialkyl glycerol tetraethers (GDGTs) have enabled past temperature reconstructions in both marine and terrestrial environments. Nevertheless, to date these methods have not been widely applied in high latitude environments due to poor performance of the GDGT-temperature calibrations at lower temperatures. To address this we studied 32 lakes from Antarctica, the sub-Antarctic Islands and Southern Chile to: 1) quantify their GDGT composition and investigate the environmental controls on GDGT composition; and 2) develop a GDGT-temperature calibration model for inferring past temperatures from Antarctic and sub-Antarctic lakes. GDGTs were found in all 32 lakes studied and in 31 lakes branched GDGTs (brGDGTs) were the dominant compounds. Statistical analyses of brGDGT composition in relation to temperature, pH, conductivity and water depth showed that the composition of brGDGTs is strongly correlated with mean summer air temperature (MSAT). This enabled the development of the first regional brGDGT-temperature calibration for use in Antarctic and sub-Antarctic lakes using four brGDGT compounds (GDGT-Ib, GDGT-II, GDGT-III and GDGT-IIIb). A key discovery was that GDGT-IIIb is of particular importance in cold lacustrine environments. The addition of this compound significantly improved the model's performance from r2 = 0.67, RMSEP-LOO (leave-one-out) = 2.23 °C, RMSEP-H (h-block) = 2.37 °C when applying the re-calibrated global GDGT-temperature calibration to our Antarctic dataset to r2 = 0.83, RMSEP-LOO = 1.68 °C, RMSEP-H = 1.65 °C for our new Antarctic calibration. This shows that Antarctic and sub-Antarctic, and possibly other high latitude, palaeotemperature reconstructions should be based on a regional GDGT-temperature calibration where specific

  15. (137)Cs concentrations in Atlantic and western Antarctic surface waters: results of the 7th Ukrainian Antarctic Expedition, 2002.

    Science.gov (United States)

    Gulin, S B; Stokozov, N A

    2005-01-01

    The latitudinal distribution of (137)Cs in the Atlantic--western Antarctic surface waters was studied during the 7th Ukrainian Antarctic Expedition in January--May 2002. The (137)Cs concentrations have also been measured in the upper ice of the coastal glacier Woozle Hill located near the Ukrainian Antarctic station "Akademik Vernadsky" (western Antarctica, 65 degrees 15' S-64 degrees 16' W). Comparison of these data with results of previous same-route expeditions SWEDARP (Swedish Antarctic Research Expedition, 1988/1989) and the French R/V "Jeanne d'Arc" (1992/1993), has shown practically parallel changes of (137)Cs surface concentrations between 40 degrees N and 20 degrees S, pointing to decrease of (137)Cs radioactivity at these latitudes with an apparent half-life of 10--15 years (12.5+/-2.1 years on average). This suggests that decrease of (137)Cs surface concentration within this latitude band is controlled, besides the radioactive decay of (137)Cs (half-life=30 years), by vertical mixing of the upper water masses. South of 20 degrees S, the (137)Cs concentrations in surface water have decreased more rapidly because of the influence of the less contaminated Antarctic waters. At 50--60 degrees S and near the Antarctic coast, the (137)Cs activity in 2002 was similar to those measured during the SWEDARP and "Jeanne d'Arc" expeditions, suggesting an additional input of (137)Cs to these waters from the melted ice from the adjacent glaciers.

  16. Comparison of similar Arctic and Antarctic morphotypes of heterotrophic protists regarding their genotypes and ecotypes.

    Science.gov (United States)

    Nitsche, Frank; Arndt, Hartmut

    2015-02-01

    The polar regions offer the opportunity to study possible diversification processes of spatially and temporally separated populations. We focused our study on similar morphotypes/species (e. g. species with the same morphology) of heterotrophic flagellates and ciliates originating from both, Antarctic and Arctic waters: 38 populations of six choanoflagellate morphospecies (Acanthocorbis unguiculata, Helgoeca nana, Diaphanoeca grandis, Savillea micropora, Stephanoeca apheles, Salpingoeca tuba), four other flagellate morphospecies (Cafeteria roenbergensis, Podomonas magma, Procryptobia sorokini, Protaspis sp.) and three ciliate morphospecies (Holosticha sp., Uronema marinum, Pseudocohnilembus persalinus). We analysed similarities and differences regarding their genotypes (SSU rDNA) and for several species regarding morphotypes and autecology (temperature and salinity tolerance). Most of the investigated polar protists were psychrophilic and showed a high salinity tolerance. Morphologically well defined acanthoecid choanoflagellates isolated from both poles showed the lowest intraspecific diversity (< 0.5% p-distance). No intragenomic polymorphism of SSU rDNA within one individual and among clones from one population occurred. The way of dispersal for acanthoecid choanoflagellates still remains unclear. Even under extreme stress none of the examined cultures formed cysts. Single cell PCR appeared to be an appropriate method to investigate species not available as monoclonal cultures. As a prerequisite for barcoding, acanthoecid choanoflagellate species have a very low intraspecific variability regarding SSU rDNA. There was a clear correlation between autecological, morphological and molecular data sets, which may help interpreting molecular data from clone libraries or next generation sequencing. Copyright © 2014 Elsevier GmbH. All rights reserved.

  17. Cultivable fungi present in Antarctic soils: taxonomy, phylogeny, diversity, and bioprospecting of antiparasitic and herbicidal metabolites.

    Science.gov (United States)

    Gomes, Eldon C Q; Godinho, Valéria M; Silva, Débora A S; de Paula, Maria T R; Vitoreli, Gislaine A; Zani, Carlos L; Alves, Tânia M A; Junior, Policarpo A S; Murta, Silvane M F; Barbosa, Emerson C; Oliveira, Jaquelline G; Oliveira, Fabio S; Carvalho, Camila R; Ferreira, Mariana C; Rosa, Carlos A; Rosa, Luiz H

    2018-05-01

    Molecular biology techniques were used to identify 218 fungi from soil samples collected from four islands of Antarctica. These consisted of 22 taxa of 15 different genera belonging to the Zygomycota, Ascomycota, and Basidiomycota. Mortierella, Antarctomyces, Pseudogymnoascus, and Penicillium were the most frequently isolated genera and Penicillium tardochrysogenum, Penicillium verrucosus, Goffeauzyma gilvescens, and Mortierella sp. 2 the most abundant taxa. All fungal isolates were cultivated using solid-state fermentation to obtain their crude extracts. Pseudogymnoascus destructans, Mortierella parvispora, and Penicillium chrysogenum displayed antiparasitic activities, whilst extracts of P. destructans, Mortierella amoeboidea, Mortierella sp. 3, and P. tardochrysogenum showed herbicidal activities. Reported as pathogenic for bats, different isolates of P. destructans exhibited trypanocidal activities and herbicidal activity, and may be a source of bioactive molecules to be considered for chemotherapy against neglected tropical diseases. The abundant presence of P. destructans in soils of the four islands gives evidence supporting that soils in the Antarctic Peninsula constitute a natural source of strains of this genus, including some P. destructans strains that are phylogenetically close to those that infect bats in North America and Europe/Palearctic Asia.

  18. Pigments from UV-resistant Antarctic bacteria as photosensitizers in Dye Sensitized Solar Cells.

    Science.gov (United States)

    Órdenes-Aenishanslins, N; Anziani-Ostuni, G; Vargas-Reyes, M; Alarcón, J; Tello, A; Pérez-Donoso, J M

    2016-09-01

    Here we report the use of pigments produced by UV-resistant Antarctic bacteria as photosensitizers in Dye Sensitized Solar Cells (DSSCs). Pigments were obtained from red and yellow colored psychrotolerant bacteria isolated from soils of King George Island, Antarctica. Based on metabolic characteristics and 16s DNA sequence, pigmented bacteria were identified as Hymenobacter sp. (red) and Chryseobacterium sp. (yellow). Pigments produced by these microorganisms were extracted and classified as carotenoids based on their spectroscopic and structural characteristics, determined by UV-Vis spectrophotometry and infrared spectroscopy (FTIR), respectively. With the purpose of develop green solar cells based on bacterial pigments, the photostability and capacity of these molecules as light harvesters in DSSCs were determined. Absorbance decay assays determined that bacterial carotenoids present high photostability. In addition, solar cells based on these photosensitizers exhibit an open circuit voltage (VOC) of 435.0 [mV] and a short circuit current density (ISC) of 0.2 [mA·cm(-2)] for the red pigment, and a VOC of 548.8 [mV] and a ISC of 0.13 [mA·cm(-2)] for the yellow pigment. This work constitutes the first approximation of the use of pigments produced by non-photosynthetic bacteria as photosensitizers in DSSCs. Determined photochemical characteristics of bacterial pigments, summed to their easy obtention and low costs, validates its application as photosensitizers in next-generation biological solar cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. An unusual giant pycnogonid (Pycnogonida-Colossendeidae) Decolopoda qasimi sp. nov. from Antarctic waters

    Digital Repository Service at National Institute of Oceanography (India)

    Jayasree, V.; Sreepada, R.A; Parulekar, A

    Five specimens of benthic pycnogonids collected from the Southern Ocean are described. Of these, two are identified as Nymphon australis (Hodgson) and two as Ecleipsotherma spinosa (Hodgson). One specimen under the class Colossendeidae, is described...

  20. Some oceanographic observations in the polynya and along a section in the southwest Indian/ Antarctic Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    , silicate, pH and alkalinity through Antarctic, subantarctic and subtropical zones are presented and discussed. The Antarctic Divergence is observed appreciably to the south of its previously reported positions around 20~'E longitude, indicating some...

  1. Temperature adaptation of soil bacterial communities along an Antarctic climate gradient: predicting responses to climate warming.

    NARCIS (Netherlands)

    Rinnan, R.; Rousk, J.; Yergeau, E.; Kowalchuk, G.A.; Baath, E.

    2009-01-01

    Soil microorganisms, the central drivers of terrestrial Antarctic ecosystems, are being confronted with increasing temperatures as parts of the continent experience considerable warming. Here we determined short-term temperature dependencies of Antarctic soil bacterial community growth rates, using

  2. US International Trans-Antarctic Scientific Expedition (US ITASE) Glaciochemical Data, Version 2

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains sub-annually resolved ice core chemistry data from various sites on the Antarctic Ice Sheet during the US International Trans-Antarctic...

  3. Temperature adaptation of soil bacterial communities along an Antarctic climate gradient: predicting responses to climate warming

    NARCIS (Netherlands)

    Rinnan, R.; Rousk, J.; Yergeau, E.; Kowalchuk, G.A.; Baath, E.

    2009-01-01

    Soil microorganisms, the central drivers of terrestrial Antarctic ecosystems, are being confronted with increasing temperatures as parts of the continent experience considerable warming. Here we determined short-term temperature dependencies of Antarctic soil bacterial community growth rates, using

  4. Fuzzy SP-irresolute functions

    International Nuclear Information System (INIS)

    Abbas, S.E.

    2004-01-01

    In this paper, fuzzy SP-irresolute, fuzzy SP-irresolute open and fuzzy SP-irresolute closed functions between fuzzy topological spaces in Sostak sense are defined. Their properties and the relationships between these functions and other functions introduced previously are investigated. Next fuzzy SP-connectedness is introduced and studied with the help of r-fuzzy strongly preopen sets

  5. Investigation of the biosynthesis of acetyl-CoA and oxaloacetic acid from pyruvic acid and the quantitative evaluation of incorporated 13C-labeled l-alanine in Arthrobacter hyalinus

    International Nuclear Information System (INIS)

    Katsumi Iida

    2014-01-01

    Studies on the contribution to acetyl-CoA and oxaloacetic acid from the pyruvic acid transformation from l-alanine in Arthrobacter hyalinus were conducted by means of feeding experiments with l-[1- 13 C]alanine and l-[3- 13 C]alanine, followed by an analysis of the labeling patterns of coproporphyrinogen III using 13 C NMR spectroscopy. The results demonstrated that l-alanine was transformed via pyruvic acid to both acetyl-CoA and oxaloacetic acid. Additionally, the quantitative analysis indicated that pyruvic acid was transformed to acetyl-CoA and oxaloacetic acid in the ratio of 1:0.8. (author)

  6. Skip spawning as a reproductive strategy in Antarctic fish species: the Antarctic silverfish (Pleuragramma antarctica case study

    Directory of Open Access Journals (Sweden)

    Eva Pisano

    2015-11-01

    Full Text Available The Antarctic silverfish Pleuragramma antarctica (Notothenioidei, Nototheniidae is the most abundant pelagic fish inhabiting the frigid Antarctic coastal waters. It plays relevant roles in the local ecosystems, where it is often considered a keystone species connecting lower and upper trophic levels within the coastal marine food web. Despite its ecological relevance, and although many aspects of the Antarctic silverfish biology have already been elucidated, knowledge on important components of its life cycle, including the reproductive features, is still poor. The available data on the reproduction of the Antarctic silverfish remains fragmentary and, in particular, information on the silverfish from the Ross Sea is lacking, in spite of the intensive ecological studies on this unique region and the fact that the only known nursery ground for this species is located in Terra Nova Bay (Ross Sea where hatching occurs under the sea-ice. We present the here first description of the reproductive features of Antarctic silverfish from fish sampled in late Summer (mid February 2008 in the Ross Sea. The gross reproductive traits are consistent with those reported from other Antarctic sectors but, interestingly, widespread follicular atresia has been detected in the fish examined. The intensity and prevalence of such a follicular degenerative process suggest that skip spawning (not all adults spawn every year could be a reproductive strategy of this Antarctic species. Such an hypothesis is discussed both on the short-term and on the evolutionary time-scale. Overall, the data presented also contribute to support the acknowledgment that skip-spawning is a diffuse phenomenon in fishes.

  7. Prospects for surviving climate change in Antarctic aquatic species

    Directory of Open Access Journals (Sweden)

    Peck Lloyd S

    2005-06-01

    Full Text Available Abstract Maritime Antarctic freshwater habitats are amongst the fastest changing environments on Earth. Temperatures have risen around 1°C and ice cover has dramatically decreased in 15 years. Few animal species inhabit these sites, but the fairy shrimp Branchinecta gaini typifies those that do. This species survives up to 25°C daily temperature fluctuations in summer and passes winter as eggs at temperatures down to -25°C. Its annual temperature envelope is, therefore around 50°C. This is typical of Antarctic terrestrial species, which exhibit great physiological flexibility in coping with temperature fluctuations. The rapidly changing conditions in the Maritime Antarctic are enhancing fitness in these species by increasing the time available for feeding, growth and reproduction, as well as increasing productivity in lakes. The future problem these animals face is via displacement by alien species from lower latitudes. Such invasions are now well documented from sub-Antarctic sites. In contrast the marine Antarctic environment has very stable temperatures. However, seasonality is intense with very short summers and long winter periods of low to no algal productivity. Marine animals grow slowly, have long generation times, low metabolic rates and low levels of activity. They also die at temperatures between +5°C and +10°C. Failure of oxygen supply mechanisms and loss of aerobic scope defines upper temperature limits. As temperature rises, their ability to perform work declines rapidly before lethal limits are reached, such that 50% of populations of clams and limpets cannot perform essential activities at 2–3°C, and all scallops are incapable of swimming at 2°C. Currently there is little evidence of temperature change in Antarctic marine sites. Models predict average global sea temperatures will rise by around 2°C by 2100. Such a rise would take many Antarctic marine animals beyond their survival limits. Animals have 3 mechanisms for

  8. Responses of Antarctic Oscillation to global warming

    Science.gov (United States)

    Feng, S.

    2015-12-01

    The Antarctic Oscillation (AAO) is the major annular mode dominates the spatiotemporal variability of the atmospheric circulation in the Southern Hemisphere. This study examined the sensitivity of AAO to future warming by analyzing the outputs of 34 state-of-the-art climate models participating in phase 5 of the Coupled Model Intercomparion Project (CMIP5). The model simulations include the stabilized (RCP4.5) and business as usual (RCP8.5) scenarios as well as the idealized 1% per year increase in atmospheric CO2 to quadrupling (1pctCO2) and an instantaneous quadrupling of CO2 (abrupt4xCO2). We show that the CMIP5 models on average simulate increases in the AAO in every season by 2100 under the RCP4.5 and RCP8.5 scenarios. However, due to the impacts of ozone, aerosol and land use changes, the amplitudes of the projected changes in AAO to future climate scenarios are quit different on different seasons. After the impact of ozone, aerosol and land use changes were removed; it was found that the impact of greenhouse gases (GHGs) on AAO is similar on all seasons. The increases of AAO are accelerating following the increase of GHGs. Our results are also consistent with the simulations of 1pctCO2 and abrupt4xCO2.

  9. Summer diet of the Salvin's prion at sub-Antarctic Marion Island

    African Journals Online (AJOL)

    1988-02-14

    Feb 14, 1988 ... Thirty-nine food samples were collected from Salvin's prions Pachyptila salvini at sub-Antarctic Marion Island,. Prince Edward Islands. ..... guide to foraging methods used by marine birds in. Antarctic and sub-Antarctic seas. BIOMASS Handbook. 24: 1-22. GRINDLEY, J.R. & LANE, S.B. 1979. Zooplankton.

  10. Isolation and characterization of a Pseudomonas sp. strain IITR01 capable of degrading α-endosulfan and endosulfan sulfate.

    Science.gov (United States)

    Bajaj, A; Pathak, A; Mudiam, M R; Mayilraj, S; Manickam, N

    2010-12-01

    To isolate bacteria capable of degrading endosulfan (ES) and the more toxic ES sulfate and to characterize their metabolites. A Pseudomonas sp. strain IITR01 capable of degrading α-ES and toxic ES sulfate was isolated using technical-ES through enrichment culture techniques. No growth and no degradation were observed using β-ES. Thin-layer chromatography and gas chromatography-mass spectrum analysis revealed the disappearance of both α-ES and ES sulfate and the formation of hydroxylated products ES diol, ether and lactone. We show here for the first time the formation of aforementioned metabolites in contrast to ES hemisulfate yielded by an Arthrobacter sp. Metabolism of α-ES and endosulfate was also observed using the crude cell extract of IITR01. The molecular mass of protein induced during the degradation of α-ES and sulfate as substrate was found to be approximately 150 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). We describe characterization of bacterium capable of degrading α-ES and ES sulfate but not β-ES. Genetic investigation suggests that a gene nonhomologous to the reported esd may be present in the strain IITR01. This study describes toxic ES degradation by a Pseudomonas species that may be utilized for the bioremediation of the industrial soils contaminated with ES residues. © 2010 The Authors. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology.

  11. Monitoring Antarctic ice sheet surface melting with TIMESAT algorithm

    Science.gov (United States)

    Ye, Y.; Cheng, X.; Li, X.; Liang, L.

    2011-12-01

    Antarctic ice sheet contributes significantly to the global heat budget by controlling the exchange of heat, moisture, and momentum at the surface-atmosphere interface, which directly influence the global atmospheric circulation and climate change. Ice sheet melting will cause snow humidity increase, which will accelerate the disintegration and movement of ice sheet. As a result, detecting Antarctic ice sheet melting is essential for global climate change research. In the past decades, various methods have been proposed for extracting snowmelt information from multi-channel satellite passive microwave data. Some methods are based on brightness temperature values or a composite index of them, and others are based on edge detection. TIMESAT (Time-series of Satellite sensor data) is an algorithm for extracting seasonality information from time-series of satellite sensor data. With TIMESAT long-time series brightness temperature (SSM/I 19H) is simulated by Double Logistic function. Snow is classified to wet and dry snow with generalized Gaussian model. The results were compared with those from a wavelet algorithm. On this basis, Antarctic automatic weather station data were used for ground verification. It shows that this algorithm is effective in ice sheet melting detection. The spatial distribution of melting areas(Fig.1) shows that, the majority of melting areas are located on the edge of Antarctic ice shelf region. It is affected by land cover type, surface elevation and geographic location (latitude). In addition, the Antarctic ice sheet melting varies with seasons. It is particularly acute in summer, peaking at December and January, staying low in March. In summary, from 1988 to 2008, Ross Ice Shelf and Ronnie Ice Shelf have the greatest interannual variability in amount of melting, which largely determines the overall interannual variability in Antarctica. Other regions, especially Larsen Ice Shelf and Wilkins Ice Shelf, which is in the Antarctic Peninsula

  12. Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea ice

    Directory of Open Access Journals (Sweden)

    R. S. Humphries

    2016-02-01

    Full Text Available Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the Antarctic region is currently based on measurements that are often limited to boundary layer air masses at spatially sparse coastal and continental research stations, with only a handful of studies in the vast sea-ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the icebreaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3 concentrations exhibited a five-fold increase moving across the polar front, with mean polar cell concentrations of 1130 cm−3 – higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low-pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air masses quickly from the free troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea-ice boundary layer air masses travelled equatorward into the low-albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei which, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between

  13. Antarctic volcanoes: A remote but significant hazard

    Science.gov (United States)

    Geyer, Adelina; Martí, Alex; Folch, Arnau; Giralt, Santiago

    2017-04-01

    Ash emitted during explosive volcanic eruptions can be dispersed over massive areas of the globe, posing a threat to both human health and infrastructures, such as the air traffic. Some of the last eruptions occurred during this decade (e.g. 14/04/2010 - Eyjafjallajökull, Iceland; 24/05/2011-Grímsvötn, Iceland; 05/06/2011-Puyehue-Cordón Caulle, Chile) have strongly affected the air traffic in different areas of the world, leading to economic losses of billions of euros. From the tens of volcanoes located in Antarctica, at least nine are known to be active and five of them have reported volcanic activity in historical times. However, until now, no attention has been paid to the possible social, economical and environmental consequences of an eruption that would occur on high southern latitudes, perhaps because it is considered that its impacts would be minor or local, and mainly restricted to the practically inhabited Antarctic continent. We show here, as a case study and using climate models, how volcanic ash emitted during a regular eruption of one of the most active volcanoes in Antarctica, Deception Island (South Shetland Islands), could reach the African continent as well as Australia and South America. The volcanic cloud could strongly affect the air traffic not only in the region and at high southern latitudes, but also the flights connecting Africa, South America and Oceania. Results obtained are crucial to understand the patterns of volcanic ash distribution at high southern latitudes with obvious implications for tephrostratigraphical and chronological studies that provide valuable isochrones with which to synchronize palaeoclimate records. This research was partially funded by the MINECO grants VOLCLIMA (CGL2015-72629-EXP)and POSVOLDEC(CTM2016-79617-P)(AEI/FEDER, UE), the Ramón y Cajal research program (RYC-2012-11024) and the NEMOH European project (REA grant 34 agreement n° 289976).

  14. Diversity of cultivable fungi associated with Antarctic marine sponges and screening for their antimicrobial, antitumoral and antioxidant potential.

    Science.gov (United States)

    Henríquez, Marlene; Vergara, Karen; Norambuena, Javiera; Beiza, Andrea; Maza, Felipe; Ubilla, Pamela; Araya, Ivanna; Chávez, Renato; San-Martín, Aurelio; Darias, José; Darias, María J; Vaca, Inmaculada

    2014-01-01

    The diversity of sponge-associated fungi has been poorly investigated in remote geographical areas like Antarctica. In this study, 101 phenotypically different fungal isolates were obtained from 11 sponge samples collected in King George Island, Antarctica. The analysis of ITS sequences revealed that they belong to the phylum Ascomycota. Sixty-five isolates belong to the genera Geomyces, Penicillium, Epicoccum, Pseudeurotium, Thelebolus, Cladosporium, Aspergillus, Aureobasidium, Phoma, and Trichocladium but 36 isolates could not be identified at genus level. In order to estimate the potential of these isolates as producers of interesting bioactivities, antimicrobial, antitumoral and antioxidant activities of fungal culture extracts were assayed. Around 51% of the extracts, mainly from the genus Geomyces and non identified relatives, showed antimicrobial activity against some of the bacteria tested. On the other hand, around 42% of the extracts showed potent antitumoral activity, Geomyces sp. having the best performance. Finally, the potential of the isolated fungi as producers of antioxidant activity seems to be moderate. Our results suggest that fungi associated with Antarctic sponges, particularly Geomyces, would be valuable sources of antimicrobial and antitumoral compounds. To our knowledge, this is the first report describing the biodiversity and the metabolic potential of fungi associated with Antarctic marine sponges.

  15. Pogonophryne neyelovi, a new species of Antarctic short-barbeled plunderfish (Perciformes, Notothenioidei, Artedidraconidae from the deep Ross Sea

    Directory of Open Access Journals (Sweden)

    Gennadiy Shandikov

    2013-04-01

    Full Text Available This paper continues descriptions of new deep-water Antarctic barbeled plunderfishes of the poorly known and the most speciose notothenioid genus Pogonophryne. It is based on a comprehensive collection obtained by the authors in 2009–2010 during an Antarctic toothfish (Dissostichus mawsoni fishing trip. A new species, the hopbeard plunderfish P. neyelovi, the twenty-second species of the genus, is described. The new species belongs to dorsally-spotted short-barbeled species forming the “P. mentella” group. Pogonophryne neyelovi sp.n. is characterized by the following combination of characters: a very short and small mental barbel with an ovaloid and short terminal expansion covered by flattened scale-like processes that are mostly bluntly palmate; a moderately protruding lower jaw; a high second dorsal fin almost uniformly black and lacking a sharply elevated anterior lobe; pectoral fins striped anteriorly and uniformly light posteriorly; the anal and pelvic fins light; the dorsal surface of the head and the area anterior to the first dorsal fin covered with large, irregular dark brown blotches and spots; the ventral surface of the head, breast and belly without sharp dark markings. The new species is compared to the closest species P. brevibarbata, P. tronio, and P. ventrimaculata. English vernacular names are proposed for all species of the genus.

  16. {sup 137}Cs concentrations in Atlantic and western Antarctic surface waters: results of the 7th Ukrainian Antarctic Expedition, 2002

    Energy Technology Data Exchange (ETDEWEB)

    Gulin, S.B. [Institute of Biology of the Southern Seas (IBSS), 2, Nakhimov Av., Sevastopol, 99011 (Ukraine)]. E-mail: sergei@gulin.sebastopol.ua; Stokozov, N.A. [Institute of Biology of the Southern Seas (IBSS), 2, Nakhimov Av., Sevastopol, 99011 (Ukraine)

    2005-07-01

    The latitudinal distribution of {sup 137}Cs in the Atlantic-western Antarctic surface waters was studied during the 7th Ukrainian Antarctic Expedition in January-May 2002. The {sup 137}Cs concentrations have also been measured in the upper ice of the coastal glacier Woozle Hill located near the Ukrainian Antarctic station 'Akademik Vernadsky' (western Antarctica, 65 deg 15' S-64 deg 16' W). Comparison of these data with results of previous same-route expeditions SWEDARP (Swedish Antarctic Research Expedition, 1988/1989) and the French R/V 'Jeanne d'Arc' (1992/1993), has shown practically parallel changes of {sup 137}Cs surface concentrations between 40 deg N and 20 deg S, pointing to decrease of {sup 137}Cs radioactivity at these latitudes with an apparent half-life of 10-15 years (12.5{+-}2.1 years on average). This suggests that decrease of {sup 137}Cs surface concentration within this latitude band is controlled, besides the radioactive decay of {sup 137}Cs (half-life=30 years), by vertical mixing of the upper water masses. South of 20 deg S, the {sup 137}Cs concentrations in surface water have decreased more rapidly because of the influence of the less contaminated Antarctic waters. At 50-60 deg S and near the Antarctic coast, the {sup 137}Cs activity in 2002 was similar to those measured during the SWEDARP and 'Jeanne d'Arc' expeditions, suggesting an additional input of {sup 137}Cs to these waters from the melted ice from the adjacent glaciers.

  17. Environmental Factors Influencing Antarctic Krill Recruitment along the Western Antarctic Peninsula

    Science.gov (United States)

    Cope, J. S.; Steinberg, D. K.; Thanassekos, S.

    2016-02-01

    Climate warming in the Western Antarctic Peninsula (WAP) is impacting pelagic food web structure. Antarctic krill, Euphausia superba, are a critical food-web link between primary producers and higher trophic levels such as penguins, seals, and whales. Climate-induced changes in krill recruitment are thus an important consideration when evaluating future WAP ecosystem trends. We examined long-term (1993 to 2015) and spatial (north/south) changes in summer krill recruitment. Krill were collected within the epipelagic zone during the Palmer Antarctica Long-Term Ecological Research (PAL LTER) cruises within a 700 x 260 km sampling grid along the WAP. Krill from each tow were enumerated and their lengths were measured. A simple recruitment index based on the proportion of krill smaller than 40 mm (F40) was used in our analyses. There was a significant 5-6-year cyclical trend in F40. In the last 5 years, the southern population has begun to deviate from this cycle. To investigate potential environmental factors leading to this pattern in recruitment success, F40 was regressed with environmental factors and climatological indices for both the whole PAL LTER grid and north/south sub-regions. Over the whole grid, F40 was positively correlated with chlorophyll a and primary production, both with a 1-year lag. Spatially, these trends were strongest for chlorophyll in the north, and primary production in the south. Krill recruitment in the south was also correlated to climatological indices such as the Multivariate El Niño/Southern Oscillation Index (MEI). These correlations could be used to forecast future krill population changes.

  18. A method for the production of D-tagatose using a recombinant Pichia pastoris strain secreting β-D-galactosidase from Arthrobacter chlorophenolicus and a recombinant L-arabinose isomerase from Arthrobacter sp. 22c

    OpenAIRE

    Wanarska Marta; Kur Józef

    2012-01-01

    Abstract Background D-Tagatose is a natural monosaccharide which can be used as a low-calorie sugar substitute in food, beverages and pharmaceutical products. It is also currently being tested as an anti-diabetic and obesity control drug. D-Tagatose is a rare sugar, but it can be manufactured by the chemical or enzymatic isomerization of D-galactose obtained by a β-D-galactosidase-catalyzed hydrolysis of milk sugar lactose and the separation of D-glucose and D-galactose. L-Arabinose isomerase...

  19. Cryptosporidium sp. in lizards

    Czech Academy of Sciences Publication Activity Database

    Koudela, Břetislav; Modrý, D.

    1998-01-01

    Roč. 45, č. 1 (1998), s. 8 ISSN 1066-5234. [ Cryptosporidium sp. in lazards. 01.01.1998-02.01.1998, Praha] R&D Projects: GA ČR GA508/95/0273; GA AV ČR IPP2020702 Subject RIV: fp - Other Medical Disciplines

  20. A multivariate analysis of Antarctic sea ice since 1979

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes Neto, Newton de; Evangelista, Heitor [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Tanizaki-Fonseca, Kenny [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Universidade Federal Fluminense (UFF), Dept. Analise Geoambiental, Inst. de Geociencias, Niteroi, RJ (Brazil); Penello Meirelles, Margareth Simoes [Universidade do Estado do Rio de Janeiro (UERJ)/Geomatica, Maracana, Rio de Janeiro, RJ (Brazil); Garcia, Carlos Eiras [Universidade Federal do Rio Grande (FURG), Laboratorio de Oceanografia Fisica, Rio Grande, RS (Brazil)

    2012-03-15

    Recent satellite observations have shown an increase in the total extent of Antarctic sea ice, during periods when the atmosphere and oceans tend to be warmer surrounding a significant part of the continent. Despite an increase in total sea ice, regional analyses depict negative trends in the Bellingshausen-Amundsen Sea and positive trends in the Ross Sea. Although several climate parameters are believed to drive the formation of Antarctic sea ice and the local atmosphere, a descriptive mechanism that could trigger such differences in trends are still unknown. In this study we employed a multivariate analysis in order to identify the response of the Antarctic sea ice with respect to commonly utilized climate forcings/parameters, as follows: (1) The global air surface temperature, (2) The global sea surface temperature, (3) The atmospheric CO{sub 2} concentration, (4) The South Annular Mode, (5) The Nino 3, (6) The Nino (3 + 4, 7) The Nino 4, (8) The Southern Oscillation Index, (9) The Multivariate ENSO Index, (10) the Total Solar Irradiance, (11) The maximum O{sub 3} depletion area, and (12) The minimum O{sub 3} concentration over Antarctica. Our results indicate that western Antarctic sea ice is simultaneously impacted by several parameters; and that the minimum, mean, and maximum sea ice extent may respond to a separate set of climatic/geochemical parameters. (orig.)

  1. Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

    NARCIS (Netherlands)

    Rugenstein, Maria; Stocchi, Paolo; von der Heydt, Anna; Dijkstra, Hendrik; Brinkhuis, Henk

    2014-01-01

    During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~34 Myr) by combining solid Earth and ocean dynamic

  2. Metagenomic analysis of a Southern Maritime Antarctic soil

    Directory of Open Access Journals (Sweden)

    David Anthony Pearce

    2012-12-01

    Full Text Available Our current understanding of Antarctic soils is derived from direct culture on selective media, biodiversity studies based on clone library construction and analysis, quantitative PCR amplification of specific gene sequences and the application of generic microarrays for microbial community analysis. Here, we investigated the biodiversity and functional potential of a soil community at Mars Oasis on Alexander Island in the southern Maritime Antarctic, by applying 454 pyrosequencing technology to a metagenomic library constructed from soil genomic DNA. The results suggest that the commonly cited range of phylotypes used in clone library construction and analysis of 78-730 OTUs (de-replicated to 30-140 provides low coverage of the major groups present (~5%. The vast majority of functional genes (>77% were for structure, carbohydrate metabolism and DNA/RNA processing and modification. This study suggests that prokaryotic diversity in Antarctic terrestrial environments appears to be limited at the generic level, with Proteobacteria, Actinobacteria being common. Cyanobacteria were surprisingly under-represented at 2.6% of sequences, although ~1% of the genes identified were involved in CO2 fixation. At the sequence level there appeared to be much greater heterogeneity, and this might be due to high divergence within the relatively restricted lineages which have successfully colonized Antarctic terrestrial environments.

  3. Evaluating Wind Power Potential in the Spanish Antarctic Base (BAE)

    International Nuclear Information System (INIS)

    Arribas, L.M.; Garcia Barquero, C; Navarro, J.; Cuerva, A.; Cruz, I.; Roque, V.; Marti, I.

    2000-01-01

    The objective of the work is to model wind field in the surroundings of the Spanish Antarctic Base (BAE in the following). The need of such a work comes from the necessity of an energy source able to supply the energy demand in the BAE during the Antarctic winter. When the BAE is in operation (in the Antarctic summer) the energy supply comes from a diesel engine. In the Antarctic winter the base is closed, but the demand of energy supply is growing up every year because of the increase in the number of technical and scientific machines that remain in the BAE taking different measurements. For this purpose the top of a closed hill called Pico Radio, not perturbed by close obstacles, has been chosen as the better site for the measurements. The measurement station is made up with a sonic anemometer and a small wind generator to supply the energy needed by the sensors head heating of the anemometer. This way, it will be also used as a proof for the suitability of a wind generator in the new chosen site, under those special climatic conditions.(Author) 3 refs

  4. During the British Antarctic Survey's Offshore Biological Programme ...

    African Journals Online (AJOL)

    spamer

    bearing distal portion. The. Antarctic material has tentacular club suckers which possess, on the distal half of the ring, a prominent central recurved median tooth flanked by two triangular teeth on each side. The proximal half of the ring is smooth.

  5. 77 FR 5403 - Conservation of Antarctic Animals and Plants

    Science.gov (United States)

    2012-02-03

    ... NATIONAL SCIENCE FOUNDATION 45 CFR Part 670 Conservation of Antarctic Animals and Plants AGENCY... practice and procedure, Antarctica, Exports, Imports, Plants, Reporting and recordkeeping requirements... Plaque Commemorating the PM-3A Nuclear Power Plant at McMurdo Station. HSM 86 No.1 Building Commemorating...

  6. Genetics differentiation between Arctic and Antarctic monothalamous foraminiferans

    DEFF Research Database (Denmark)

    Pawlowski, Jan; Majewski, Wojciech; Longet, David

    2008-01-01

    distinct genetically. As expected, Arctic specimens were usually more closely related to those from Northern Europe than to their Antarctic representatives. The deep-sea specimens from Weddell Sea branched as a sister to the McMurdo Sound population, while those from the Arctic Ocean clustered with ones...

  7. Distribution of dissolved and particulate metals in Antarctic sea ice

    NARCIS (Netherlands)

    Lannuzel, D.; Bowie, A.R.; van der Merwe, P.C.; Townsend, A.T.; Schoemann, V.

    2011-01-01

    Samples were collected in East Antarctic sea ice in late winter/early austral spring 2007 to assess the distributions of Al, Cr, Mn, Cu, Zn, Mo. Cd and Ba. Total dissolved (<02 mu m) and particulate (>0.2 mu m) concentrations were measured by Inductively Coupled Plasma-Sector Field Mass Spectrometry

  8. Estimates of numbers of kelp gulls and Kerguelen and Antarctic ...

    African Journals Online (AJOL)

    Four species are regular breeders at the islands: Subantarctic skua Catharacta antarctica, kelp gull Larus dominicanus, Antarctic tern Sterna vittata and Kerguelen tern S. virgata. The latter three species currently each have populations of below 150 breeding pairs at the islands. Kelp gull numbers appear to be relatively ...

  9. Present and future variations in Antarctic firn air content

    NARCIS (Netherlands)

    Ligtenberg, S. R M; Kuipers Munneke, P.; Van Den Broeke, M. R.

    2014-01-01

    A firn densification model (FDM) is used to assess spatial and temporal (1979-2200) variations in the depth, density and temperature of the firn layer covering the Antarctic ice sheet (AIS). A time-dependent version of the FDM is compared to more commonly used steady-state FDM results. Although the

  10. South African Antarctic research programme 1978-1982

    CSIR Research Space (South Africa)

    SASCAR

    1978-12-01

    Full Text Available This document provides a comprehensive review of the planned South African scientific activities in Antarctica and on the sub-Antarctic islands in the five year period starting in 1978. The scientific programmes are classified under five headings...

  11. Dating Antarctic ice sheet collapse: Proposing a molecular genetic approach

    Science.gov (United States)

    Strugnell, Jan M.; Pedro, Joel B.; Wilson, Nerida G.

    2018-01-01

    Sea levels at the end of this century are projected to be 0.26-0.98 m higher than today. The upper end of this range, and even higher estimates, cannot be ruled out because of major uncertainties in the dynamic response of polar ice sheets to a warming climate. Here, we propose an ecological genetics approach that can provide insight into the past stability and configuration of the West Antarctic Ice Sheet (WAIS). We propose independent testing of the hypothesis that a trans-Antarctic seaway occurred at the last interglacial. Examination of the genomic signatures of bottom-dwelling marine species using the latest methods can provide an independent window into the integrity of the WAIS more than 100,000 years ago. Periods of connectivity facilitated by trans-Antarctic seaways could be revealed by dating coalescent events recorded in DNA. These methods allow alternative scenarios to be tested against a fit to genomic data. Ideal candidate taxa for this work would need to possess a circumpolar distribution, a benthic habitat, and some level of genetic structure indicated by phylogeographical investigation. The purpose of this perspective piece is to set out an ecological genetics method to help resolve when the West Antarctic Ice Shelf last collapsed.

  12. Petrology of Antarctic Eucrites PCA 91078 and PCA 91245

    Science.gov (United States)

    Howard, L. M.; Domanik, K. J.; Drake, M. J.; Mittlefehldt, D. W.

    2002-01-01

    Antarctic eucrites PCA 91078 and PCA 91245, are petrographically characterized and found to be unpaired, type 6, basaltic eucrites. Observed textures that provide insight into the petrogenesis of these meteorites are also discussed. Additional information is contained in the original extended abstract.

  13. Molecular evolution of hemoglobins of Antarctic fishes (Notothenioidei)

    NARCIS (Netherlands)

    Stam, W.T.; Beintema, J.J; D Avino, R.; Tamburrini, M.; di Prisco, G.

    1997-01-01

    Amino acid sequences of alpha- and beta-chains of human hemoglobin and of hemoglobins of coelacanth and 24 teleost fish species, including 11 antarctic and two temperate Notothenioidei, were analyzed using maximum parsimony. Trees were derived for the alpha- and beta-chains separately and for

  14. Maneuver simulation model of an experimental hovercraft for the Antarctic

    Science.gov (United States)

    Murao, Rinichi

    Results of an investigation of a hovercraft model designed for Antarctic conditions are presented. The buoyancy characteristics, the propellant control system, and simulation model control are examined. An ACV (air cushion vehicle) model of the hovercraft is used to examine the flexibility and friction of the skirt. Simulation results are presented which show the performance of the hovercraft.

  15. Is vertical migration in Antarctic krill (Euphausia superba) influenced ...

    Indian Academy of Sciences (India)

    Antarctic krill (Euphausia superba) is a keystone species in the southern ocean ecosystem where it is the main consumer of phytoplankton and constitutes the main food item of many higher predators. Both food and predators are most abundant at the surface, thus krill hide in the depth of the ocean during the day and ...

  16. Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

    NARCIS (Netherlands)

    Rugenstein, M.; Stocchi, P.; van der Heydt, A.; Brinkhuis, H.

    2014-01-01

    During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~ 34 Myr) by combining solid Earth and ocean

  17. Microbial ecology and biogeochemistry of continental Antarctic soils

    Directory of Open Access Journals (Sweden)

    Don A Cowan

    2014-04-01

    Full Text Available The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbour microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths possess a genetic capacity for nitrogen and carbon cycling, polymer degradation and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities.

  18. Modeling the Thermal Interactions of Meteorites Below the Antarctic Ice

    Science.gov (United States)

    Oldroyd, William Jared; Radebaugh, Jani; Stephens, Denise C.; Lorenz, Ralph; Harvey, Ralph; Karner, James

    2017-10-01

    Meteorites with high specific gravities, such as irons, appear to be underrepresented in Antarctic collections over the last 40 years. This underrepresentation is in comparison with observed meteorite falls, which are believed to represent the actual population of meteorites striking Earth. Meteorites on the Antarctic ice sheet absorb solar flux, possibly leading to downward tunneling into the ice, though observations of this in action are very limited. This descent is counteracted by ice sheet flow supporting the meteorites coupled with ablation near mountain margins, which helps to force meteorites towards the surface. Meteorites that both absorb adequate thermal energy and are sufficiently dense may instead reach a shallow equilibrium depth as downward melting overcomes upward forces during the Antarctic summer. Using a pyronometer, we have measured the incoming solar flux at multiple depths in two deep field sites in Antarctica, the Miller Range and Elephant Moraine. We compare these data with laboratory analogues and model the thermal and physical interactions between a variety of meteorites and their surroundings. Our Matlab code model will account for a wide range of parameters used to characterize meteorites in an Antarctic environment. We will present the results of our model along with depth estimates for several types of meteorites. The recovery of an additional population of heavy meteorites would increase our knowledge of the formation and composition of the solar system.

  19. Antarctic meteorology, a study with automatic weather stations

    NARCIS (Netherlands)

    Reijmer, C.H.

    2001-01-01

    This thesis chiefly addresses a) the use of Automatic Weather Stations (AWS) in determining the near-surface climate and heat budget of Antarctica and, specifically, Dronning Maud Land (DML), and b) the determination of source regions of Antarctic moisture with the aid of a trajectory model and an

  20. Sector of West Antarctic Ice Sheet in "Irreversible Retreat"

    Science.gov (United States)

    Showstack, Randy

    2014-05-01

    A large sector of the West Antarctic Ice Sheet "has gone into a state of irreversible retreat," according to glaciologist Eric Rignot, lead author of the paper "Widespread rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler Glaciers in West Antarctica from 1992 to 2011," which has been accepted for publication in Geophysical Research Letters (GRL).

  1. Calving fluxes and basal melt rates of Antarctic ice shelves

    NARCIS (Netherlands)

    Depoorter, M.A.; Bamber, J.L.; Griggs, J.A.; Lenaerts, J.T.M.|info:eu-repo/dai/nl/314850163; Ligtenberg, S.R.M.|info:eu-repo/dai/nl/32821177X; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; Moholdt, G.

    2013-01-01

    Iceberg calving has been assumed to be the dominant cause of mass loss for the Antarctic ice sheet, with previous estimates of the calving flux exceeding 2,000 gigatonnes per year1, 2. More recently, the importance of melting by the ocean has been demonstrated close to the grounding line and near

  2. Dynamic thinning of glaciers on the Southern Antarctic Peninsula

    NARCIS (Netherlands)

    Wouters, B.; Martin-Espanol, A.; Helm, V.; Flament, T.; van Wessem, J. M.; Ligtenberg, S. R. M.; van den Broeke, M. R.; Bamber, J. L.

    2015-01-01

    Growing evidence has demonstrated the importance of ice shelf buttressing on the inland grounded ice, especially if it is resting on bedrock below sea level. Much of the Southern Antarctic Peninsula satisfies this condition and also possesses a bed slope that deepens inland. Such ice sheet geometry

  3. TEMPERATURE REQUIREMENTS AND BIOGEOGRAPHY OF ANTARCTIC, ARCTIC AND AMPHIEQUATORIAL SEAWEEDS

    NARCIS (Netherlands)

    WIENCKE, C; BARTSCH, [No Value; BISCHOFF, B; PETERS, AF; BREEMAN, AM

    The temperature requirements for growth and survival of cold water seaweeds from both Hemispheres are compared and discussed in relation to the climatic history of the various regions and in relation to the origin of amphiequatorial distribution patterns. Endemic Antarctic species are most strongly

  4. Recent Rapid Regional Climate Warming on the Antarctic Peninsula

    Science.gov (United States)

    Vaughan, D. G.; Marshall, G. J.; Connolley, W. M.; Parkinson, C.; Mulvaney, R.; Hodgson, D. A.; King, J. C.; Pudsey, C. J.; Turner, J.

    2002-12-01

    The Intergovernmental Panel on Climate Change (IPCC) confirmed that global warming was 0.6 ñ 0.2 degrees C during the 20th Century and cited increases in greenhouse gases as a likely contributor. But this average conceals the complexity of observed climate change, which is seasonally biased, decadally variable and geographically patchy. In particular, over the last 50 years three high-latitude areas have undergone recent rapid regional (RRR) warming ? substantially more rapid than the global mean. We discuss the spatial and temporal significance of RRR warming in one area, the Antarctic Peninsula. New analyses of station records show no ubiquitous polar amplification of global warming but significant RRR warming on the Antarctic Peninsula. We investigate the likelihood that this could be amplification of a global warming, and use climate-proxy data to indicate that this RRR warming on the Antarctic Peninsula is unprecedented over the last two millennia and unlikely to be a natural mode of variability. We can show a strong connection between RRR warming and reduced sea-ice duration in an area on the west of the Antarctic Peninsula, but here we cannot yet distinguish cause and effect. Thus for the present we cannot determine which process causes the RRR warming, and until the mechanism initiating and sustaining it is understood, and is convincingly reproduced in climate models, we lack a sound basis for predicting climate change in this region over the coming century.

  5. Holocene subsurface temperature variability in the eastern Antarctic continental margin

    NARCIS (Netherlands)

    Kim, J.H.; Crosta, X.; Willmott, V.; Renssen, H.; Bonnin, J.; Helmke, P.; Schouten, S.; Sinninghe Damsté, J.S.

    2012-01-01

    We reconstructed subsurface (similar to 45-200 m water depth) temperature variability in the eastern Antarctic continental margin during the late Holocene, using an archaeal lipid-based temperature proxy (TEX86 L). Our results reveal that subsurface temperature changes were probably positively

  6. Eight glacial cycles from an Antarctic ice core

    NARCIS (Netherlands)

    Oerlemans, J.

    2004-01-01

    The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not

  7. UV radiation and primary production in the Antarctic waters

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Krishnakumari, L.; Bhattathiri, P.M.A.; Chandramohan, D.

    of depth from 21/1/94 to 6/3/94. Fifteen stations in the Antarctic waters (69 degrees 53 minutes to 70 degrees 02 second S) and 6 en route (64 degrees 53 minutes 30 degrees 01 minutes S) were analysed. The average values for surface chlorophyll a and pp...

  8. Freshwater invertebrates of sub-Antarctic Marion Island | Dartnall ...

    African Journals Online (AJOL)

    Antarctic Marion Island were examined for invertebrates. Sixty-eight species were found, including 45 new records for the Island. Of these 56 were bona fide aquatic invertebrates, the rest being terrestrial or brackish interlopers that had fallen or been ...

  9. EBSD in Antarctic and Greenland Ice

    Science.gov (United States)

    Weikusat, Ilka; Kuiper, Ernst-Jan; Pennock, Gill; Sepp, Kipfstuhl; Drury, Martyn

    2017-04-01

    boundaries. However, an almost equal number of tilt subgrain boundaries were measured, involving dislocations gliding on non-basal planes (prism or prism slip). A few subgrain boundaries involving prism edge dislocation glide, as well as boundaries involving basal twist dislocation slip, were also identified. The finding that subgrain boundaries built up by dislocations gliding on non-basal planes are as frequent as those originating from basal plane slip is surprising and has impact on the discussion on rate-controlling processes for the ice flow descriptions of large ice masses with respect to sea-level evolution. Weikusat, I.; Miyamoto, A.; Faria, S. H.; Kipfstuhl, S.; Azuma, N. & Hondoh, T.: Subgrain boundaries in Antarctic ice quantified by X-ray Laue diffraction J. Glaciol., 2011, 57, 85-94

  10. Is there a distinct continental slope fauna in the Antarctic?

    Science.gov (United States)

    Kaiser, Stefanie; Griffiths, Huw J.; Barnes, David K. A.; Brandão, Simone N.; Brandt, Angelika; O'Brien, Philip E.

    2011-02-01

    The Antarctic continental slope spans the depths from the shelf break (usually between 500 and 1000 m) to ˜3000 m, is very steep, overlain by 'warm' (2-2.5 °C) Circumpolar Deep Water (CDW), and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the abyssal fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell Sea and Scotia Sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III, BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ (Ecology of the Antarctic Sea Ice Zone) II cruises as well as current databases (SOMBASE, SCAR-MarBIN), four different taxa were selected (i.e. cheilostome bryozoans, isopod and ostracod crustaceans and echinoid echinoderms) and two areas, the Weddell Sea and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations. Benthic samples were collected using Agassiz trawl, epibenthic sledge and Rauschert sled. By bathymetric definition, these data suggest that despite eurybathy in some of the groups examined and apparent similarity of physical conditions in the Antarctic, the shelf, slope and abyssal faunas were clearly separated in the Weddell Sea. However, no such separation of faunas was apparent in the Scotia Sea (except in echinoids). Using a geomorphological definition of the slope, shelf-slope-abyss similarity only changed significantly in the bryozoans. Our results did not support the presence of a homogenous and unique Antarctic slope fauna despite a high number of species being restricted to the slope. However, it remains the case that there may be

  11. On the origin and evolution of Antarctic Peracarida (Crustacea, Malacostraca

    Directory of Open Access Journals (Sweden)

    Angelika Brandt

    1999-12-01

    Full Text Available The early separation of Gondwana and the subsequent isolation of Antarctica caused a long evolutionary history of its fauna. Both, long environmental stability over millions of years and habitat heterogeneity, due to an abundance of sessile suspension feeders on the continental shelf, favoured evolutionary processes of preadapted taxa, like for example the Peracarida. This taxon performs brood protection and this might be one of the most important reasons why it is very successful (i.e. abundant and diverse in most terrestrial and aquatic environments, with some species even occupying deserts. The extinction of many decapod crustaceans in the Cenozoic might have allowed the Peracarida to find and use free ecological niches. Therefore the palaeogeographic, palaeoclimatologic, and palaeo-hydrographic changes since the Palaeocene (at least since about 60 Ma ago and the evolutionary success of some peracarid taxa (e.g. Amphipoda, Isopoda led to the evolution of many endemic species in the Antarctic. Based on a phylogenetic analysis of the Antarctic Tanaidacea, Sieg (1988 demonstrated that the tanaid fauna of the Antarctic is mainly represented by phylogenetically younger taxa, and data from other crustacean taxa led Sieg (1988 to conclude that the recent Antarctic crustacean fauna must be comparatively young. His arguments are scrutinized on the basis of more recent data on the phylogeny and biodiversity of crustacean taxa, namely the Ostracoda, Decapoda, Mysidacea, Cumacea, Amphipoda, and Isopoda. This analysis demonstrates that the origin of the Antarctic fauna probably has different roots: an adaptive radiation of descendants from old Gondwanian ancestors was hypothesized for the isopod families Serolidae and Arcturidae, an evolution and radiation of phylogenetically old taxa in Antarctica could also be shown for the Ostracoda and the amphipod family Iphimediidae. A recolonization via the Scotia Arc appears possible for some species, though it is

  12. Microbial biomass and basal respiration of selected Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

    Science.gov (United States)

    Abakumov, E.; Mukhametova, N.

    2014-07-01

    Antarctica is a unique place for soil, biological, and ecological investigations. Soils of Antarctica have been studied intensively during the last century, when different national Antarctic expeditions visited the sixth continent with the aim of investigating nature and the environment. Antarctic investigations are comprised of field surveys mainly in the terrestrial landscapes, where the polar stations of different countries are situated. That is why the main and most detailed soil surveys were conducted in the McMurdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann Hills and the Schirmacher Oasis. Our investigations were conducted during the 53rd and 55th Russian Antarctic expeditions in the base of soil pits, and samples were collected in Sub-Antarctic and Antarctic regions. Sub-Antarctic or maritime landscapes are considered to be very different from Antarctic landscapes due to differing climatic and geogenic conditions. Soils of diverse zonal landscapes were studied with the aim of assessing the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. This investigation shows that Antarctic soils are quite diverse in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod) organo-mineral horizons as well as by an upper organic layer. The most developed organic layers were revealed in peat soils of King George Island, where its thickness reach, in some cases, was 80 cm. These soils as well as soils formed under guano are characterized by the highest amount of total organic carbon (TOC), between 7.22 and 33.70%. Coastal and continental Antarctic soils exhibit less developed Leptosols, Gleysols, Regolith and rare Ornhitosol, with TOC levels between 0.37 and 4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones, which can be interpreted as a result of higher amounts of fresh organic

  13. Climate change and trophic response of the Antarctic bottom fauna.

    Directory of Open Access Journals (Sweden)

    Richard B Aronson

    Full Text Available BACKGROUND: As Earth warms, temperate and subpolar marine species will increasingly shift their geographic ranges poleward. The endemic shelf fauna of Antarctica is especially vulnerable to climate-mediated biological invasions because cold temperatures currently exclude the durophagous (shell-breaking predators that structure shallow-benthic communities elsewhere. METHODOLOGY/PRINCIPAL FINDINGS: We used the Eocene fossil record from Seymour Island, Antarctic Peninsula, to project specifically how global warming will reorganize the nearshore benthos of Antarctica. A long-term cooling trend, which began with a sharp temperature drop approximately 41 Ma (million years ago, eliminated durophagous predators-teleosts (modern bony fish, decapod crustaceans (crabs and lobsters and almost all neoselachian elasmobranchs (modern sharks and rays-from Antarctic nearshore waters after the Eocene. Even prior to those extinctions, durophagous predators became less active as coastal sea temperatures declined from 41 Ma to the end of the Eocene, approximately 33.5 Ma. In response, dense populations of suspension-feeding ophiuroids and crinoids abruptly appeared. Dense aggregations of brachiopods transcended the cooling event with no apparent change in predation pressure, nor were there changes in the frequency of shell-drilling predation on venerid bivalves. CONCLUSIONS/SIGNIFICANCE: Rapid warming in the Southern Ocean is now removing the physiological barriers to shell-breaking predators, and crabs are returning to the Antarctic Peninsula. Over the coming decades to centuries, we predict a rapid reversal of the Eocene trends. Increasing predation will reduce or eliminate extant dense populations of suspension-feeding echinoderms from nearshore habitats along the Peninsula while brachiopods will continue to form large populations, and the intensity of shell-drilling predation on infaunal bivalves will not change appreciably. In time the ecological effects of

  14. Climate change and trophic response of the Antarctic bottom fauna.

    Science.gov (United States)

    Aronson, Richard B; Moody, Ryan M; Ivany, Linda C; Blake, Daniel B; Werner, John E; Glass, Alexander

    2009-01-01

    As Earth warms, temperate and subpolar marine species will increasingly shift their geographic ranges poleward. The endemic shelf fauna of Antarctica is especially vulnerable to climate-mediated biological invasions because cold temperatures currently exclude the durophagous (shell-breaking) predators that structure shallow-benthic communities elsewhere. We used the Eocene fossil record from Seymour Island, Antarctic Peninsula, to project specifically how global warming will reorganize the nearshore benthos of Antarctica. A long-term cooling trend, which began with a sharp temperature drop approximately 41 Ma (million years ago), eliminated durophagous predators-teleosts (modern bony fish), decapod crustaceans (crabs and lobsters) and almost all neoselachian elasmobranchs (modern sharks and rays)-from Antarctic nearshore waters after the Eocene. Even prior to those extinctions, durophagous predators became less active as coastal sea temperatures declined from 41 Ma to the end of the Eocene, approximately 33.5 Ma. In response, dense populations of suspension-feeding ophiuroids and crinoids abruptly appeared. Dense aggregations of brachiopods transcended the cooling event with no apparent change in predation pressure, nor were there changes in the frequency of shell-drilling predation on venerid bivalves. Rapid warming in the Southern Ocean is now removing the physiological barriers to shell-breaking predators, and crabs are returning to the Antarctic Peninsula. Over the coming decades to centuries, we predict a rapid reversal of the Eocene trends. Increasing predation will reduce or eliminate extant dense populations of suspension-feeding echinoderms from nearshore habitats along the Peninsula while brachiopods will continue to form large populations, and the intensity of shell-drilling predation on infaunal bivalves will not change appreciably. In time the ecological effects of global warming could spread to other portions of the Antarctic coast. The differential

  15. Regional Antarctic snow accumulation over the past 1000 years

    Science.gov (United States)

    Thomas, Elizabeth R.; Melchior van Wessem, J.; Roberts, Jason; Isaksson, Elisabeth; Schlosser, Elisabeth; Fudge, Tyler J.; Vallelonga, Paul; Medley, Brooke; Lenaerts, Jan; Bertler, Nancy; van den Broeke, Michiel R.; Dixon, Daniel A.; Frezzotti, Massimo; Stenni, Barbara; Curran, Mark; Ekaykin, Alexey A.

    2017-11-01

    Here we present Antarctic snow accumulation variability at the regional scale over the past 1000 years. A total of 79 ice core snow accumulation records were gathered and assigned to seven geographical regions, separating the high-accumulation coastal zones below 2000 m of elevation from the dry central Antarctic Plateau. The regional composites of annual snow accumulation were evaluated against modelled surface mass balance (SMB) from RACMO2.3p2 and precipitation from ERA-Interim reanalysis. With the exception of the Weddell Sea coast, the low-elevation composites capture the regional precipitation and SMB variability as defined by the models. The central Antarctic sites lack coherency and either do not represent regional precipitation or indicate the model inability to capture relevant precipitation processes in the cold, dry central plateau. Our results show that SMB for the total Antarctic Ice Sheet (including ice shelves) has increased at a rate of 7 ± 0.13 Gt decade-1 since 1800 AD, representing a net reduction in sea level of ˜ 0.02 mm decade-1 since 1800 and ˜ 0.04 mm decade-1 since 1900 AD. The largest contribution is from the Antarctic Peninsula (˜ 75 %) where the annual average SMB during the most recent decade (2001-2010) is 123 ± 44 Gt yr-1 higher than the annual average during the first decade of the 19th century. Only four ice core records cover the full 1000 years, and they suggest a decrease in snow accumulation during this period. However, our study emphasizes the importance of low-elevation coastal zones, which have been under-represented in previous investigations of temporal snow accumulation.

  16. Regional Antarctic snow accumulation over the past 1000 years

    Directory of Open Access Journals (Sweden)

    E. R. Thomas

    2017-11-01

    Full Text Available Here we present Antarctic snow accumulation variability at the regional scale over the past 1000 years. A total of 79 ice core snow accumulation records were gathered and assigned to seven geographical regions, separating the high-accumulation coastal zones below 2000 m of elevation from the dry central Antarctic Plateau. The regional composites of annual snow accumulation were evaluated against modelled surface mass balance (SMB from RACMO2.3p2 and precipitation from ERA-Interim reanalysis. With the exception of the Weddell Sea coast, the low-elevation composites capture the regional precipitation and SMB variability as defined by the models. The central Antarctic sites lack coherency and either do not represent regional precipitation or indicate the model inability to capture relevant precipitation processes in the cold, dry central plateau. Our results show that SMB for the total Antarctic Ice Sheet (including ice shelves has increased at a rate of 7 ± 0.13 Gt decade−1 since 1800 AD, representing a net reduction in sea level of ∼ 0.02 mm decade−1 since 1800 and ∼ 0.04 mm decade−1 since 1900 AD. The largest contribution is from the Antarctic Peninsula (∼ 75 % where the annual average SMB during the most recent decade (2001–2010 is 123 ± 44 Gt yr−1 higher than the annual average during the first decade of the 19th century. Only four ice core records cover the full 1000 years, and they suggest a decrease in snow accumulation during this period. However, our study emphasizes the importance of low-elevation coastal zones, which have been under-represented in previous investigations of temporal snow accumulation.

  17. At-Sea Distribution and Prey Selection of Antarctic Petrels and Commercial Krill Fisheries.

    Directory of Open Access Journals (Sweden)

    Sébastien Descamps

    Full Text Available Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the Southern Ocean, there is an extensive fishery for Antarctic krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the Antarctic krill fisheries and the distribution of a krill dependent seabird, the Antarctic petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest Antarctic petrel colony (Svarthamaren, Dronning Maud Land, located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and Antarctic petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of Antarctic krill consumed by Antarctic petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by Antarctic petrels did not differ in size from that taken by trawls or from krill taken by most Antarctic krill predators. Selectivity for specific Antarctic krill stages seems generally low in Antarctic predators. Overall, our results show that competition between Antarctic petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the Antarctic petrel may occur, even with birds breeding thousands of kilometers away.

  18. Spectroscopic characterization of Antarctic marine aerosol

    Science.gov (United States)

    Paglione, Marco; Zanca, Nicola; Rinaldi, Matteo; Dall'osto, Manuel; Simo, Rafel; Facchini, Maria Cristina; Decesari, Stefano

    2017-04-01

    Marine aerosol constitutes an important and not thoroughly investigated natural aerosol system. In particular, the poor knowledge of the physical-chemical properties of primary (sea-spray) and secondary particles, especially over biologically active seawaters, affects the current capability of modeling the effect of marine aerosol on climate (O'Dowd et al., 2004). In polar regions, surface seawater composition and its exchanges with the atmosphere is complicated also by the presence of sea-ice and of the variety of micro-organisms (viruses, prokaryotes and microalgae) living within it (Levasseur,2013). In the framework of the Spanish project PEGASO (Plankton-derived Emission of Gases and Aerosols in the Southern Ocean) submicron aerosol samples were collected during a 6 weeks long oceanographic cruise (2nd January 2015 - 11th February 2015) conducted in the regions of Antarctic Peninsula, South Orkney and South Georgia Islands, an area of the Southern Ocean characterized every summer by both large patches of productive waters (phytoplankton blooms) and sea-ice cover. The collected samples were analyzed by means of proton-Nuclear Magnetic Resonance (H-NMR) spectroscopy with aim of organic compounds characterization in terms of functional groups and specific molecular tracers identification (Decesari et al., 2011). H-NMR spectral features resulted quite variable among the different samples both in terms of relative abundance of main functional groups and in terms of presence of specific compounds. In all the samples were found biogenic markers, like low-molecular-weight alkyl-amines and methanesulphonate (MSA), of secondary origin (formed by the condensation of vapors onto particles). Resonance signals of other aliphatic compounds of possible primary origin, like lipids, aminoacids (e.g. alanine) and sugars (e.g. sucrose) are present in variable concentrations in the samples. A hierarchical cluster analysis applied on the NMR spectra allowed to identify similarities

  19. Molecular ecophysiology of Antarctic notothenioid fishes.

    Science.gov (United States)

    Cheng, C-H Christina; Detrich, H William

    2007-12-29

    The notothenioid fishes of the Southern Ocean surrounding Antarctica are remarkable examples of organismal adaptation to extreme cold. Their evolution since the mid-Miocene in geographical isolation and a chronically cold marine environment has resulted in extreme stenothermality of the extant species. Given the unique thermal history of the notothenioids, one may ask what traits have been gained, and conversely, what characters have been lost through change in the information content of their genomes. Two dramatic changes that epitomize such evolutionary transformations are the gain of novel antifreeze proteins, which are obligatory for survival in icy seawater, by most notothenioids and the paradoxical loss of respiratory haemoproteins and red blood cells, normally deemed indispensable for vertebrate life, by the species of a highly derived notothenioid family, the icefishes. Here, we review recent advances in our understanding of these traits and their evolution and suggest future avenues of investigation. The formerly coherent paradigm of notothenioid freeze avoidance, developed from three decades of study of antifreeze glycoprotein (AFGP) based cold adaptation, now faces challenges stemming from the recent discovery of antifreeze-deficient, yet freeze-resistant, early notothenioid life stages and from definitive evidence that the liver is not the physiological source of AFGPs in notothenioid blood. The resolution of these intriguing observations is likely to reveal new physiological traits that are unique to the notothenioids. Similarly, the model of AFGP gene evolution from a notothenioid pancreatic trypsinogen-like gene precursor is being expanded and refined based on genome-level analyses of the linked AFGP loci and their ancestral precursors. Finally, the application of comparative genomics to study evolutionary change in the AFGP genotypes of cool-temperate notothenioids from sub-Antarctic habitats, where these genes are not necessary, will contribute to

  20. Tsukamurella inchonensis sp. nov.

    Science.gov (United States)

    Yassin, A F; Rainey, F A; Brzezinka, H; Burghardt, J; Lee, H J; Schaal, K P

    1995-07-01

    Chemotaxonomic and genomic 16S ribosomal DNA sequence analyses of two isolates obtained from two different clinical materials clearly delineated a new species of the genus Tsukamurella. This new species can be identified by its 16S ribosomal DNA similarity values, as well as its physiological characteristics. The name Tsukamurella inchonensis sp. nov. is proposed for these isolates, which are represented by strain IMMIB D-771T (= DSM 44067T) (T = type strain). This strain exhibits only 45% DNA relatedness to Tsukamurella paurometabola.

  1. SP-100 surety evaluation

    International Nuclear Information System (INIS)

    1985-06-01

    This report describes surety evaluations conducted during GFY 1985 in support of the General Electric design for a Space Nuclear Power System - SP-100. Those surety evaluations address both safety and safeguards requirements, which are derived from OSNP-1 and supporting documents. The report includes results of neutronics (criticality) calculations performed by Los Alamos. The results have been benchmarked against independent calculations performed by General Electric with different codes. These comparisons show close agreement, and are summarized. Los Alamos has also provided specifications of explosion and fire environments, which have been used in evaluation of the GE SP-100 concept. Following the summary of key results, surety requirements are given and recommendations toward specification of requirements for later SP-100 project phases are presented. A conceptual design summary is presented. To establish a comprehensive background for surety evaluations, a reference mission profile and potential accidents for each phase of the mission are identified. The main body of the report addresses surety of the General Electric Thermoelectric Conversion design. GE has also developed a Stirling Engine concept, and performed comprehensive surety evaluations for it. These evaluations are reported

  2. Unmanned aerial optical systems for spatial monitoring of Antarctic mosses

    Science.gov (United States)

    Lucieer, Arko; Turner, Darren; Veness, Tony; Malenovsky, Zbynek; Harwin, Stephen; Wallace, Luke; Kelcey, Josh; Robinson, Sharon

    2013-04-01

    The Antarctic continent has experienced major changes in temperature, wind speed and stratospheric ozone levels during the last 50 years. In a manner similar to tree rings, old growth shoots of Antarctic mosses, the only plants on the continent, also preserve a climate record of their surrounding environment. This makes them an ideal bio-indicator of the Antarctic climate change. Spatially extensive ground sampling of mosses is laborious and time limited due to the short Antarctic growing season. Obviously, there is a need for an efficient method to monitor spatially climate change induced stress of the Antarctic moss flora. Cloudy weather and high spatial fragmentation of the moss turfs makes satellite imagery unsuitable for this task. Unmanned aerial systems (UAS), flying at low altitudes and collecting image data even under a full overcast, can, however, overcome the insufficiency of satellite remote sensing. We, therefore, developed scientific UAS, consisting of a remote-controlled micro-copter carrying on-board different remote sensing optical sensors, tailored to perform fast and cost-effective mapping of Antarctic flora at ultra-high spatial resolution (1-10 cm depending on flight altitude). A single lens reflex (SLR) camera carried by UAS acquires multi-view aerial photography, which processed by the Structure from Motion computer vision algorithm provides an accurate three-dimensional digital surface model (DSM) at ultra-high spatial resolution. DSM is the key input parameter for modelling a local seasonal snowmelt run-off, which provides mosses with the vital water supply. A lightweight multispectral camera on-board of UVS is collecting images of six selected spectral wavebands with the full-width-half-maximum (FWHM) of 10 nm. The spectral bands can be used to compute various vegetation optical indices, e.g. Difference Vegetation Index (NDVI) or Photochemical Reflectance Index (PRI), assessing the actual physiological state of polar vegetation. Recently

  3. Treatment and prevention of infection following bites of the Antarctic fur seal (Arctocephalus gazella).

    Science.gov (United States)

    Kouliev, Timur; Cui, Victoria

    2015-01-01

    In recent decades, an increasing number of people have traveled to sub-Antarctic and Antarctic regions each year for research, tourism, and resource exploitation. Hunting of Antarctic fur seals (Arctocephalus gazella) almost pushed the species to extinction in the early 1900s, but populations have since shown rapid and substantial recovery. The species' range has re-expanded to include several islands south of the Antarctic Convergence, most notably South Georgia, and now overlaps with many popular Antarctic travel destinations. Both male and female fur seals can become extremely aggressive when provoked, and their bites, if not properly treated, pose a significant risk of infection by microorganisms not usually encountered in cases of animal bites. In this report, we present the case of a patient treated for a fur seal bite during an Antarctic expedition cruise, review the literature concerning seal bites, and suggest the use of antibiotic prophylaxis to prevent complications.

  4. Metabolic rates of the antarctic amphipod Gondogeneia antarctica at different temperatures and salinities

    OpenAIRE

    Gomes, Vicente; Passos, Maria José de Arruda Campos Rocha; Rocha, Arthur José da Silva; Santos, Thais da Cruz Alves dos; Machado, Alex Sander Dias; Ngan, Phan Van

    2013-01-01

    Changes in environmental factors may deeply affect the energy budget of Antarctic organisms as many of them are stenothermal and/or stenohaline ectotherms. In this context, the aim of this study is to contribute to knowledge on variations in the energy demand of the Antarctic amphipod, Gondogeneia antarctica as a function of temperature and salinity. Experiments were held at the Brazilian Antarctic Station "Comandante Ferraz", under controlled conditions. Animals collected at Admiralty Bay we...

  5. A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond

    OpenAIRE

    Kennicutt, M.C.; Chown, S.L.; Cassano, J.J.; Liggett, D.; Peck, L.S.; Massom, R.; Rintoul, S.R.; Storey, J.; Vaughan, D.G.; Wilson, T.J.; Allison, I.; Ayton, J.; Badhe, R.; Baeseman, J.; Barrett, P.J.

    2015-01-01

    Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to ‘scan the horizon’ to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consu...

  6. Antarctic Holocene climate change: A benthic foraminiferal stable isotope record from Palmer Deep

    OpenAIRE

    Shevenell, A. E.; Kennett, J. P.

    2002-01-01

    The first moderate- to high-resolution Holocene marine stable isotope record from the nearshore Antarctic continental shelf (Ocean Drilling Program (ODP) Hole 1098B) suggests sensitivity of the western Antarctic Peninsula hydrography to westerly wind strength and El Nino-Southern Oscillation (ENSO)-like climate variability. Despite proximity to corrosive Antarctic water masses, sufficient CaCO3 in Palmer Deep sediments exists to provide a high-quality stable isotopic record (especially in the...

  7. Are Antarctic ozone variations a manifestation of dynamics or chemistry?

    Science.gov (United States)

    Tung, K.-K.; Ko, M. K. W.; Rodriguez, J. M.; Sze, N. D.

    1986-01-01

    The existence of a reverse circulation cell with rising motion in the polar lower stratosphere is suggested as an explanation for the temporal behavior of the ozone column density in the Antarctic region. The upwelling brings ozone-poor air from below 100 mbar to the stratosphere, possibly contributing to the observed ozone decline in early spring. At the same time, the Antarctic stratosphere might contain a very low concentration of NO(x), a condition that could favor a greatly enhanced catalytic removal of O3 by halogen species. It is argued that heterogeneous processes and formation of OClO by the reaction BrO+ClO - OClO+Br before and after the polar night might help to suppress the NO(x) levels during the early spring period.

  8. The delta18O composition of Antarctic coastal current waters

    International Nuclear Information System (INIS)

    Frew, R.; Heywood, K.; Dennis, P.

    1997-01-01

    The varying proportions of 18 O to 16 O in sea water provide an oceanographic trace like salinity, but with an extra degree of freedom: salt is a tracer for the oceanic fluid, whereas the isotopic composition is a tracer specifically for the water component of that fluid. Hydrogen and oxygen isotopes are the variables most intimately related to the water component in the sea, therefore thay furnish a direct link to the water in the atmosphere and on continents and to the precipitation cycle which caused the salinity changes. The ratio of 18 O to 16 O (delta 18 O) ot waters is a powerful tracer in polar regions where sea and glacial ice processes decouple delta 18 O from salinity. Here we present observations from a significant but relatively unexplored component of the Southern Ocean current system, the Antarctic Coastal Current, and its associated Antarctic Slope Front. (author)

  9. On the manoeuvering simulation of an Antarctic hovercraft

    Science.gov (United States)

    Murao, R.; Nojiri, T.

    Since 1981 an experimental hovercraft for the Antarctic has been tested in Japan's Antarctic station Syowa. During tests on the ice field near Syowa station, it was experienced that the yaw response of this craft is very sensitive to certain ice conditions. In this report, we deal with course keeping of the craft in relative crosswinds and with the maneuvering simulation while turning. Maneuvering at large yaw angle is required to generate the effective centripetal force in turning. The trajectories based on pulse steering are obtained. The course stability is very dependent upon the friction between skirts and ground, and generally not good on smooth flat ice. It is shown, however, that the rudder automatic control provides good course stability independent of ice conditions. The trajectories obtained from the simulation show that the use of a combination of rudder control and puff ports produces quick turning.

  10. Natural and anthropogenic hydrocarbons in the Antarctic pack ice

    International Nuclear Information System (INIS)

    Nemirovskaya, I.A.; Novigatsky, A.N.

    2004-01-01

    A field experiment was conducted near the Russian Antarctic stations in May, 2001 in the Pridz Bay and coastal part of the Davies Sea to examine the content of dissolved and suspended forms of aliphatic hydrocarbons in melted snow samples, pack ice and ice cores. The site included clean control areas and polluted test areas. A spill was performed by covering the bare ice surface with marine diesel fuel. The different physical characteristics of clean and polluted ice were measured. This included radiation balance, reflected solar radiation, integral albedo radiation, surface temperature, seawater temperature, salinity at depth, and ice salinity. The study showed that accumulation of natural and anthropogenic hydrocarbon took place in the ice-water barrier zone, mostly in suspended form. It was concluded that for oil spills in pack Antarctic ice, the mechanism of filtration due to convection-diffusion plays an important role in the transformation of diesel fuel. 14 refs., 2 tabs., 2 figs

  11. Turning microplastics into nanoplastics through digestive fragmentation by Antarctic krill.

    Science.gov (United States)

    Dawson, Amanda L; Kawaguchi, So; King, Catherine K; Townsend, Kathy A; King, Robert; Huston, Wilhelmina M; Bengtson Nash, Susan M

    2018-03-08

    Microplastics (plastics microplastics through ingestion. Here, by exposing Antarctic krill (Euphausia superba) to microplastics under acute static renewal conditions, we present evidence of physical size alteration of microplastics ingested by a planktonic crustacean. Ingested microplastics (31.5 µm) are fragmented into pieces less than 1 µm in diameter. Previous feeding studies have shown spherical microplastics either; pass unaffected through an organism and are excreted, or are sufficiently small for translocation to occur. We identify a new pathway; microplastics are fragmented into sizes small enough to cross physical barriers, or are egested as a mixture of triturated particles. These findings suggest that current laboratory-based feeding studies may be oversimplifying interactions between zooplankton and microplastics but also introduces a new role of Antarctic krill, and potentially other species, in the biogeochemical cycling and fate of plastic.

  12. Control of Branchionus sp. and Amoeba sp. in cultures of Arthrospira sp. Control de Branchionus sp. y Amoeba sp. en cultivos de Arthrospira sp.

    Directory of Open Access Journals (Sweden)

    Carlos Méndez

    2012-09-01

    Full Text Available Cultivation of cyanobacterium Arthrospira sp. has been developed in many countries for the production of proteins, pigments and other compounds. Outdoor mass cultures are often affected by biological contamination, drastically reducing productivity as far as bringing death. This study evaluates the control of Branchionus sp. and Amoeba sp. with two chemical compounds: urea (U and ammonium bicarbonate (AB, in laboratory conditions and outdoor mass culture of Arthrospira sp. The lethal concentration 100 (LC100 at 24 h for Branchionus sp. and Amoeba sp. determined was of 60-80 mg L-1 (U and 100-150 mg L-1 (AB. The average effective inhibition concentration for 50% of the population (IC50 in Arthrospira sp., after 72 h, was 80 mg L-1 (U and 150 mg L-1 (AB. The application of doses of 60 mg L-1 (U or 100 mg L-1 (AB in the outdoor mass culture of this contaminated microalga, completely inhibited grazing and did not affect the growth of Arthrospira sp. but rather promoted rapid recovery of algal density at levels prior to infestation. These compounds provided an economical and effective control of predators in cultures of Arthrospira sp.El cultivo de la cianobacteria Arthrospira sp. ha sido desarrollado en muchos países para la obtención de proteínas, pigmentos y otros compuestos. Cultivo que a nivel industrial se ve afectado frecuentemente por contaminación biológica, reduciendo drásticamente la productividad hasta causar la muerte. Este estudio evalúa el control de Branchionus sp. y de Amoeba sp. con dos compuestos químicos, la urea (U y bicarbonato de amonio (AB en cultivos de Arthrospira sp. La concentración letal 100 (LC100 determinada a las 24 h para Branchionus sp. y Amoeba sp. fue de 60-80 mg L-1 (U y 100-150 mg L-1 (AB. La concentración media de inhibición efectiva, después de 72 h, para el 50% de la población (IC50 en Arthrospira fue de 80 mg L-1 (U y 150 mg L-1 (AB. La aplicación de dosis de 60 mg L-1 (U ó 100 mg L-1 (AB en

  13. Study of the Microbial Diversity of a Newly Discovered East Antarctic Freshwater Lake, L27C, and of a Perennially Ice-Covered Lake Untersee

    Science.gov (United States)

    Huang, Jonathan P.; Hoover, Richard B.; Andersen, Dale; Bej, Asim K.

    2010-01-01

    The microbial communities that reside within freshwater lakes of Schirmacher and Untersee Oases in East Antarctica must cope with extreme conditions that may include cold temperature, annual freeze-thaw cycles, exposure to UV radiation, especially during the austral summer months, low light beneath thick ice-cover, followed by seasonal darkness. The objective of this study was to assess the microbial biodiversity and distribution from samples taken from two freshwater lakes (L27C and Lake Untersee) that were collected during the Tawani 2008 International Antarctic Expedition that conducted research in this region of Antarctica. L27C is a small, previously unreported lake residing 2 km WNW of Maitri Station at Schirmacher Oasis. Biodiversity and distribution of microorganisms within the lake were studied using both culture-independent and culture-dependent methodologies based upon the analysis of eubacterial 16S rRNA gene sequences. Lake Untersee, a perennially ice-covered, ultra-oligotrophic, lake in the Otto-von-Gruber-Gebirge (Gruber Mountains) of central Dronning Maud Land was also sampled and the microbial diversity was analyzed by eubacterial 16S rRNA gene sequences derived from pure cultures. Direct culturing of water samples from each lake on separate R2A growth medium exhibited a variety of microorganisms including: Janthinobacterium, Hymenobacter, Sphingamonas, Subtercola, Deinococcus, Arthrobacter, Flavobacterium, Polaromonas, Rhodoferax and Duganella. The evaluation of samples from L27C through culture-independent methodology identified a rich microbial diversity consisting of six different phyla of bacteria. The culture-independent analysis also displayed the majority of bacteria (56%) belonged to the Class gamma-proteobacteria within the phylum Proteobacteria. Within the Class gamma-proteobacteria, Acinetobacter dominated (48%) the total microbial load. Overall, L27C exhibited 7 different phyla of bacteria and 20 different genera. Statistical analysis

  14. Basin-scale heterogeneity in Antarctic precipitation and its impact on surface mass variability

    Directory of Open Access Journals (Sweden)

    J. Fyke

    2017-11-01

    Full Text Available Annually averaged precipitation in the form of snow, the dominant term of the Antarctic Ice Sheet surface mass balance, displays large spatial and temporal variability. Here we present an analysis of spatial patterns of regional Antarctic precipitation variability and their impact on integrated Antarctic surface mass balance variability simulated as part of a preindustrial 1800-year global, fully coupled Community Earth System Model simulation. Correlation and composite analyses based on this output allow for a robust exploration of Antarctic precipitation variability. We identify statistically significant relationships between precipitation patterns across Antarctica that are corroborated by climate reanalyses, regional modeling and ice core records. These patterns are driven by variability in large-scale atmospheric moisture transport, which itself is characterized by decadal- to centennial-scale oscillations around the long-term mean. We suggest that this heterogeneity in Antarctic precipitation variability has a dampening effect on overall Antarctic surface mass balance variability, with implications for regulation of Antarctic-sourced sea level variability, detection of an emergent anthropogenic signal in Antarctic mass trends and identification of Antarctic mass loss accelerations.

  15. Introduction. Antarctic ecology: from genes to ecosystems. Part 2. Evolution, diversity and functional ecology.

    Science.gov (United States)

    Rogers, Alex D; Murphy, Eugene J; Johnston, Nadine M; Clarke, Andrew

    2007-12-29

    The Antarctic biota has evolved over the last 100 million years in increasingly isolated and cold conditions. As a result, Antarctic species, from micro-organisms to vertebrates, have adapted to life at extremely low temperatures, including changes in the genome, physiology and ecological traits such as life history. Coupled with cycles of glaciation that have promoted speciation in the Antarctic, this has led to a unique biota in terms of biogeography, patterns of species distribution and endemism. Specialization in the Antarctic biota has led to trade-offs in many ecologically important functions and Antarctic species may have a limited capacity to adapt to present climate change. These include the direct effects of changes in environmental parameters and indirect effects of increased competition and predation resulting from altered life histories of Antarctic species and the impacts of invasive species. Ultimately, climate change may alter the responses of Antarctic ecosystems to harvesting from humans. The unique adaptations of Antarctic species mean that they provide unique models of molecular evolution in natural populations. The simplicity of Antarctic communities, especially from terrestrial systems, makes them ideal to investigate the ecological implications of climate change, which are difficult to identify in more complex systems.

  16. Molluscan systematics and biostratigraphy: lower tertiary, La Meseta formation, Seymour Island, Antarctic Peninsula

    National Research Council Canada - National Science Library

    Stilwell, Jeffrey D; Zinsmeister, William J

    1992-01-01

    Contents: The Antarctic research series: statement of objectives - Acknowledgements - Abstract - Introduction - Previous investigations - Stratigraphy - Age of the La Meseta Formation - Biostratigraphy - Depositional environments...

  17. Anti-inflammatory activity in selected Antarctic benthic organisms

    OpenAIRE

    Moles, Juan; Torrent, Anna; Alcaraz, M. José; Ruhí, Ramon; Avila, Conxita

    2014-01-01

    Antarctic benthos was prospected in search for anti-inflammatory activity in polar benthic invertebrates, in two different geographical areas: deep-bottoms of the Eastern Weddell Sea and shallow-waters of the South Shetland Islands. A total of 36 benthic algae and invertebrate species were selected to perform solubility tests in order to obtain extracts that were soluble at an innocuous ethanol concentration (0.2%) for cell culture, and further test them for anti-inflammatory activity. From t...

  18. WHY ARE THERE SO MANY SPECIES OF BROODING ANTARCTIC ECHINOIDS?

    Science.gov (United States)

    Poulin, Élie; Féral, Jean-Pierre

    1996-04-01

    Marine invertebrates display a great variety of life-history traits and reproductive strategies. In echinoids, four patterns of larval development are generally recognized: planktotrophy, pelagic lecithotrophy, bottom dwelling, and brood protecting. Each broad type of free and protected development is found in all the oceans, but comparisons of the principal reproductive modes between different geographic regions have shown that they are not equally distributed. Frequency of pelagic development (planktotrophic and lecithotrophic) decreases from equator to Antarctic, where brood protecting becomes dominant. Numerous theories have been proposed to explain the richness of nonpelagic development in most marine invertebrates within the Southern Ocean. These theories can be grouped into three categories: (1) larval survival, where selection acts on larval; (2) energy allocation; and (3) dispersal. All of them consider the adaptative significance of brood protecting as the key to the success of this strategy in the Antarctic. However, the adaptative significance of brooding and the evolutionary success of this strategy in the Antarctic must be considered as two separate questions. To consider the problem at an evolutionary level, we have examined the consequences of different reproductive strategies on the genetic structure of species and on the long-term evolution of the clade. We examine this problem in the case of echinoids, a clade particularly well suited to addressing this question. In echinoids, the reduction of larval-stage duration is associated with a decrease in gene flow and consequently in the geographical scale of genetic differentiation. This allows us to reconsider the high-speciation-rate model, which leads to an increase in the number of low-dispersal species (isolation by distance). This model, previously tested by means of fossils is not satisfactory in living echinoids. Thus, the model is rebuilt with the addition of differential extinction rate

  19. Tracking the El Nino events from Antarctic ice core records

    International Nuclear Information System (INIS)

    Keskin, S.S.; Oelmez, I.

    2004-01-01

    Sodium and chlorine measurements were made by instrumental neutron activation analysis (INAA) on stratigraphically dated ice core samples from Byrd Station, Antarctica, for the last three centuries. The time period between 1969 and 1989 showed an enhanced impact on the Antarctic ice sheets from oceans in the form of marine aerosols. A disturbed ocean-atmosphere interface due to El Ni Southern Oscillation (ENSO) events seems to be a candidate for this observation in Antarctica. (author)

  20. Can Antarctic lichens acclimatize to changes in temperature?

    Science.gov (United States)

    Colesie, Claudia; Büdel, Burkhard; Hurry, Vaughan; Green, Thomas George Allan

    2018-03-01

    The Antarctic Peninsula, a tundra biome dominated by lichens and bryophytes, is an ecozone undergoing rapid temperature shifts. Such changes may demand a high physiological plasticity of the local lichen species to maintain their role as key drivers in this pristine habitat. This study examines the response of net photosynthesis and respiration to increasing temperatures for three Antarctic lichen species with different ecological response amplitudes. We hypothesize that negative effects caused by increased temperatures can be mitigated by thermal acclimation of respiration and/or photosynthesis. The fully controlled growth chamber experiment simulated intermediate and extreme temperature increases over the time course of 6 weeks. Results showed that, in contrast to our hypothesis, none of the species was able to down-regulate temperature-driven respiratory losses through thermal acclimation of respiration. Instead, severe effects on photobiont vitality demonstrated that temperatures around 15°C mark the upper limit for the two species restricted to the Antarctic, and when mycobiont demands exceeded the photobiont capacity they could not survive within the lichen thallus. In contrast, the widespread lichen species was able to recover its homoeostasis by rapidly increasing net photosynthesis. We conclude that to understand the complete lichen response, acclimation processes of both symbionts, the photo- and the mycobiont, have to be evaluated separately. As a result, we postulate that any acclimation processes in lichen are species-specific. This, together with the high degree of response variability and sensitivity to temperature in different species that co-occur spatially close, complicates any predictions regarding future community composition in the Antarctic. Nevertheless, our results suggest that species with a broad ecological amplitude may be favoured with on-going changes in temperature. © 2017 John Wiley & Sons Ltd.

  1. Ultraviolet radiation response of two heterotropy Antarctic marine bacterial

    International Nuclear Information System (INIS)

    Hernandez, Edgardo A.; Ferreyra, Gustavo A.; Mac Cormack, Walter P.

    2004-01-01

    Two Antarctic marine bacterial strains, were exposed to different irradiance of ultraviolet (UV) solar radiation using several experimental protocols and interferential filters. Results showed that both, UV-A and UV-B radiation produce deleterious effects on two tested bacterial strains. The mortality values under UVB treatments were higher than those observed under UVA treatments. UVvi strain proved to be more resistant to UV radiation than the UVps strain. (author) [es

  2. Antarctic krill 454 pyrosequencing reveals chaperone and stress transcriptome.

    Directory of Open Access Journals (Sweden)

    Melody S Clark

    Full Text Available BACKGROUND: The Antarctic krill Euphausia superba is a keystone species in the Antarctic food chain. Not only is it a significant grazer of phytoplankton, but it is also a major food item for charismatic megafauna such as whales and seals and an important Southern Ocean fisheries crop. Ecological data suggest that this species is being affected by climate change and this will have considerable consequences for the balance of the Southern Ocean ecosystem. Hence, understanding how this organism functions is a priority area and will provide fundamental data for life history studies, energy budget calculations and food web models. METHODOLOGY/PRINCIPAL FINDINGS: The assembly of the 454 transcriptome of E. superba resulted in 22,177 contigs with an average size of 492bp (ranging between 137 and 8515bp. In depth analysis of the data revealed an extensive catalogue of the cellular chaperone systems and the major antioxidant proteins. Full length sequences were characterised for the chaperones HSP70, HSP90 and the super-oxide dismutase antioxidants, with the discovery of potentially novel duplications of these genes. The sequence data contained 41,470 microsatellites and 17,776 Single Nucleotide Polymorphisms (SNPs/INDELS, providing a resource for population and also gene function studies. CONCLUSIONS: This paper details the first 454 generated data for a pelagic Antarctic species or any pelagic crustacean globally. The classical "stress proteins", such as HSP70, HSP90, ferritin and GST were all highly expressed. These genes were shown to be over expressed in the transcriptomes of Antarctic notothenioid fish and hypothesized as adaptations to living in the cold, with the associated problems of decreased protein folding efficiency and increased vulnerability to damage by reactive oxygen species. Hence, these data will provide a major resource for future physiological work on krill, but in particular a suite of "stress" genes for studies understanding

  3. Antarctic sea ice losses drive gains in benthic carbon drawdown.

    Science.gov (United States)

    Barnes, D K A

    2015-09-21

    Climate forcing of sea-ice losses from the Arctic and West Antarctic are blueing the poles. These losses are accelerating, reducing Earth's albedo and increasing heat absorption. Subarctic forest (area expansion and increased growth) and ice-shelf losses (resulting in new phytoplankton blooms which are eaten by benthos) are the only significant described negative feedbacks acting to counteract the effects of increasing CO2 on a warming planet, together accounting for uptake of ∼10(7) tonnes of carbon per year. Most sea-ice loss to date has occurred over polar continental shelves, which are richly, but patchily, colonised by benthic animals. Most polar benthos feeds on microscopic algae (phytoplankton), which has shown increased blooms coincident with sea-ice losses. Here, growth responses of Antarctic shelf benthos to sea-ice losses and phytoplankton increases were investigated. Analysis of two decades of benthic collections showed strong increases in annual production of shelf seabed carbon in West Antarctic bryozoans. These were calculated to have nearly doubled to >2x10(5) tonnes of carbon per year since the 1980s. Annual production of bryozoans is median within wider Antarctic benthos, so upscaling to include other benthos (combined study species typically constitute ∼3% benthic biomass) suggests an increased drawdown of ∼2.9x10(6) tonnes of carbon per year. This drawdown could become sequestration because polar continental shelves are typically deeper than most modern iceberg scouring, bacterial breakdown rates are slow, and benthos is easily buried. To date, most sea-ice losses have been Arctic, so, if hyperboreal benthos shows a similar increase in drawdown, polar continental shelves would represent Earth's largest negative feedback to climate change. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Maritime antarctic lakes as sentinels of climate change

    OpenAIRE

    Camacho, A.; Rochera, C.; Villaescusa, J. A.; Velázquez, D.; Toro, M.; Rico, E.; Fernández-Valiente, E.; Justel, Ana; Bañón García, Manuel; Quesada, Antonio

    2012-01-01

    Remote lakes, such as lakes from the Maritime Antarctica, can be used as sentinels of climate change, because they are mostly free of direct anthropogenic pressures, and they experience climate change as a main stressor capable of modifying the ecosystem structure and function. In this paper, the content of a lecture that has been presented at the First Conference of Lake Sustainability, which has been centred in our studies on lakes from Byers Peninsula (Maritime Antarctic...

  5. Natural thermoluminescence of Antarctic meteorites and related studies

    Science.gov (United States)

    Benoit, Paul H.; Sears, Derek W. G.

    1998-01-01

    The natural thermoluminescence (TL) laboratory's primary purpose is to provide data on newly recovered Antarctic meteorites that can be included in discovery announcements and to investigate the scientific implications of the data. Natural TL levels of meteorites are indicators of recent thermal history and terrestrial history, and the data can be used to study the orbital/radiation history of groups of meteorites (e.g., H chondrites) or to study the processes leading to the concentration of meteorites at certain sites in Antarctica. An important application of these data is the identification of fragments, or "pairs" of meteorites produced during atmospheric passage or during terrestrial weathering. Thermoluminescence data are particularly useful for pairing within the most common meteorite classes, which typically exhibit very limited petrographic and chemical diversity. Although not originally part of the laboratory's objectives, TL data are also useful in the identification and classification of petrographically or mineralogically unusual meteorites, including unequilibrated ordinary chondrites and some basaltic achondrites. In support of its primary mission, the laboratory also engages in TL studies of modern falls, finds from hot deserts, and terrestrial analogs and conducts detailed studies of the TL properties of certain classes of meteorites. These studies include the measurement of TL profiles in meteorites, the determination of TL levels of finds from the Sahara and the Nullarbor region of Australia, and comparison of TL data to other indicators of irradiation or terrestrial history, such as cosmogenic noble gas and radionuclide abundances. Our current work can be divided into five subcategories, (a) TL survey of Antarctic meteorites, (b) pairing and field relations of Antarctic meteorites, (c) characterization of TL systematics of meteorites, (d) comparison of natural TL and other terrestrial age indicators for Antarctic meteorites, and for meteorites

  6. Temperature effects on hemocyanin oxygen binding in an antarctic cephalopod.

    Science.gov (United States)

    Zielinski, S; Sartoris, F J; Pörtner, H O

    2001-02-01

    The functional relevance of oxygen transport by hemocyanin of the Antarctic octopod Megaleledone senoi and of the eurythermal cuttlefish Sepia officinalis was analyzed by continuous and simultaneous recordings of changes in pH and hemocyanin oxygen saturation in whole blood at various temperatures. These data were compared to literature data on other temperate and cold-water cephalopods (octopods and giant squid). In S. officinalis, the oxygen affinity of hemocyanin changed at deltaP50/degrees C = 0.12 kPa (pH 7.4) with increasing temperatures; this is similar to observations in temperate octopods. In M. senoi, thermal sensitivity was much smaller (delta log P50/delta pH) increased with increasing temperature in both the cuttlefish and the Antarctic octopod. At low PO2 (1.0 kPa) and pH (7.2), the presence of a large venous oxygen reserve (43% saturation) insensitive to pH reflects reduced pH sensitivity and high oxygen affinity in M. senoi hemocyanin at 0 degrees C. In S. officinalis, this reserve was 19% at pH 7.4, 20 degrees C, and 1.7 kPa O2, a level still higher than in squid. These findings suggest that the lower metabolic rate of octopods and cuttlefish compared to squid is reflected in less pH-dependent oxygen transport. Results of the hemocyanin analysis for the Antarctic octopod were similar to those reported for Vampyroteuthis--an extremely high oxygen affinity supporting a very low metabolic rate. In contrast to findings in cold-adapted giant squid, the minimized thermal sensitivity of oxygen transport in Antarctic octopods will reduce metabolic scope and thereby contribute to their stenothermality.

  7. Atmospheric Influences on the Anomalous 2016 Antarctic Sea Ice Decay

    Science.gov (United States)

    Raphael, M. N.; Schlosser, E.; Haumann, A.

    2017-12-01

    Over the past three decades, a small but significant increase in sea ice extent (SIE) has been observed in the Antarctic. However, in 2016 there was a surprisingly early onset of the melt season. The maximum Antarctic SIE was reached in August rather than end of September, and was followed by a rapid decrease. The decline of the sea ice area (SIA) started even earlier, in July. The retreat of the ice was particularly large in November where Antarctic SIE exhibited a negative anomaly (compared to the 1981-2010 average) of almost 2 Mio. km2, which, combined with reduced Arctic SIE, led to a distinct minimum in global SIE. And, satellite observations show that from November 2016 to February 2017, the daily Antarctic SIE has been at record low levels. We use sea level pressure and geopotential height data from the ECMWF- Interim reanalysis, in conjunction with sea ice data obtained from the National Snow and Ice Data Centre (NSIDC), to investigate possible atmospheric influences on the observed phenomena. Indications are that both the onset of the melt in July and the rapid decrease in SIA and SIE in November were triggered by atmospheric flow patterns related to a positive Zonal Wave 3 index, i.e. synoptic situations leading to strong meridional flow. Additionally the Southern Annular Mode (SAM) index reached its second lowest November value since the beginning of the satellite observations. It is likely that the SIE decrease was preconditioned by SIA decrease. Positive feedback effects led to accelerated melt and consequently to the extraordinary low November SIE.

  8. Measurement of the electrostatic field in aurora by antarctic rocket

    International Nuclear Information System (INIS)

    Takeya, Yoshio; Minami, Shigeyuki

    1974-01-01

    The direct measurement of the electrostatic field produced by the flow of charged particles and geomagnetic field in aurora has been carried out by means of rockets or satellites. The construction of an electric field meter and its characteristics are described, which measures the vectors of electric field with antarctic rockets. New scheme is presented: three components of an electric field are directly obtained through the probes set in three directions. (Mori, K.)

  9. Human impacts on Antarctic ecosystems: do not forget the microorganisms!

    OpenAIRE

    Hughes, Kevin; Verleyen, Elie; Vyverman, Wim; Obbels, Dagmar; Willems, Anne; Stelmach Pessi, Igor; Laughinghouse IV, Haywood; Wilmotte, Annick

    2013-01-01

    The tiny and microscopic creatures that are the permanent inhabitants of the Antarctic continent are often overlooked in environmental impact assessments and when new management and protection strategies are designed. This lack of consideration is probably due to their small size and the need of sophisticated molecular methods to study their diversity, evolution and geographic distribution. However, considerable progress has been made in the field of molecular diversity in the last two dec...

  10. First results from imaging riometer installed at Indian Antarctic ...

    Indian Academy of Sciences (India)

    Cosmic noise absorption (CNA) measurred by imaging riometer, is an excellent tool to passively study the high latitude D-region ionospheric conditions and dynamics. An imaging riometer has been installed at Indian Antarctic station Maitri (geographic 70.75°S, 11.75°E; corrected geomagnetic 63.11°S, 53.59°E) in ...

  11. Observation of very low frequency emissions at Indian Antarctic ...

    Indian Academy of Sciences (India)

    Recently, we have succeeded in recording VLF emissions at the Indian Antarctic station, Maitri (geom. lat. 62° S, geom. long. 57.23°E, =4.5) using a T-type antenna, pre/main amplifiers and digital audio tape recorder. VLF hiss in the frequency ranges 11–13 kHz and 13–14.5 kHz and some riser-type emissions in the ...

  12. Geochemical signatures of tephras from Quaternary Antarctic Peninsula volcanoes

    OpenAIRE

    Kraus,Stefan; Kurbatov,Andrei; Yates,Martin

    2013-01-01

    In the northern Antarctic Peninsula area, at least 12 Late Plelstocene-Holocene volcanic centers could be potential sources of tephra layers in the region. We present unique geochemical fingerprints for ten of these volcanoes using major, trace, rare earth element, and isotope data from 95 samples of tephra and other eruption products. The volcanoes have predominantly basaltic and basaltic andesitic compositions. The Nb/Y ratio proves useful to distinguish between volcanic centers located on ...

  13. Antarctic krill 454 pyrosequencing reveals chaperone and stress transcriptome.

    Science.gov (United States)

    Clark, Melody S; Thorne, Michael A S; Toullec, Jean-Yves; Meng, Yan; Guan, Le Luo; Peck, Lloyd S; Moore, Stephen

    2011-01-06

    The Antarctic krill Euphausia superba is a keystone species in the Antarctic food chain. Not only is it a significant grazer of phytoplankton, but it is also a major food item for charismatic megafauna such as whales and seals and an important Southern Ocean fisheries crop. Ecological data suggest that this species is being affected by climate change and this will have considerable consequences for the balance of the Southern Ocean ecosystem. Hence, understanding how this organism functions is a priority area and will provide fundamental data for life history studies, energy budget calculations and food web models. The assembly of the 454 transcriptome of E. superba resulted in 22,177 contigs with an average size of 492bp (ranging between 137 and 8515bp). In depth analysis of the data revealed an extensive catalogue of the cellular chaperone systems and the major antioxidant proteins. Full length sequences were characterised for the chaperones HSP70, HSP90 and the super-oxide dismutase antioxidants, with the discovery of potentially novel duplications of these genes. The sequence data contained 41,470 microsatellites and 17,776 Single Nucleotide Polymorphisms (SNPs/INDELS), providing a resource for population and also gene function studies. This paper details the first 454 generated data for a pelagic Antarctic species or any pelagic crustacean globally. The classical "stress proteins", such as HSP70, HSP90, ferritin and GST were all highly expressed. These genes were shown to be over expressed in the transcriptomes of Antarctic notothenioid fish and hypothesized as adaptations to living in the cold, with the associated problems of decreased protein folding efficiency and increased vulnerability to damage by reactive oxygen species. Hence, these data will provide a major resource for future physiological work on krill, but in particular a suite of "stress" genes for studies understanding marine ectotherms' capacities to cope with environmental change.

  14. Extracellular protease from the antarctic yeast Candida humicola.

    OpenAIRE

    Ray, M K; Devi, K U; Kumar, G S; Shivaji, S

    1992-01-01

    The psychrotrophic, dimorphic yeast Candida humicola, isolated from Antarctic soil, secretes an acidic protease into the medium. The secretion of this protease by C. humicola was found to be dependent on the composition of the medium. In YPD or yeast nitrogen base medium containing either amino acids or ammonium sulfate as the nitrogen source, the activity of the protease in the medium was low (basal level). However, when yeast nitrogen base medium was depleted of amino acids or ammonium sulf...

  15. Renal conservation of antifreeze peptide in Antarctic eelpout, Rhigophila dearborni.

    Science.gov (United States)

    Eastman, J T; De Vries, A L; Coalson, R E; Nordquist, R E; Boyd, R B

    1979-11-08

    In Antarctic notothenioid fishes large amounts (3% w/v) of small molecular weights of 2,600-23,500 and would be expected to be filtered into the urine, they remain in the blood because the kidneys of these fishes contain only aglomerular nephrons. Unlike the situation in most fishes, urine formation is the result of secretion rather than filtration and reabsorption. On the other hand, the peptide antifreezes in Northern Hemisphere fishes such as the winter flounder. Pseudopleuronectes americanus, are retained by the glomerular kidney even though inulin, of comparable weight, is rapidly filtered from the blood into the urine. The Antarctic eelpout (zoarcid), Rhigophila dearborni, which is unrelated to either the Antarctic notothenioids or P. americanus, also uses a peptide antifreeze (molecular weight 6,000) which is maintained at a concentration of 3% (w/v) in the blood plasma. We report here that the lack of antifreeze in the urine of R. dearborni probably reflects the fact that the glomeruli are not functional and cannot filter. We support this conclusion with morphological and physiological evidence and relate our findings to the conservation of biological antifreeze necessary for life in ice-laden polar waters.

  16. Glacial isostatic stress shadowing by the Antarctic ice sheet

    Science.gov (United States)

    Ivins, E. R.; James, T. S.; Klemann, V.

    2005-01-01

    Numerous examples of fault slip that offset late Quaternary glacial deposits and bedrock polish support the idea that the glacial loading cycle causes earthquakes in the upper crust. A semianalytical scheme is presented for quantifying glacial and postglacial lithospheric fault reactivation using contemporary rock fracture prediction methods. It extends previous studies by considering differential Mogi-von Mises stresses, in addition to those resulting from a Coulomb analysis. The approach utilizes gravitational viscoelastodynamic theory and explores the relationships between ice mass history and regional seismicity and faulting in a segment of East Antarctica containing the great Antarctic Plate (Balleny Island) earthquake of 25 March 1998 (Mw 8.1). Predictions of the failure stress fields within the seismogenic crust are generated for differing assumptions about background stress orientation, mantle viscosity, lithospheric thickness, and possible late Holocene deglaciation for the D91 Antarctic ice sheet history. Similar stress fracture fields are predicted by Mogi-von Mises and Coulomb theory, thus validating previous rebound Coulomb analysis. A thick lithosphere, of the order of 150-240 km, augments stress shadowing by a late melting (middle-late Holocene) coastal East Antarctic ice complex and could cause present-day earthquakes many hundreds of kilometers seaward of the former Last Glacial Maximum grounding line.

  17. Sudden increase in Antarctic sea ice: Fact or artifact?

    Science.gov (United States)

    Screen, J. A.

    2011-07-01

    Three sea ice data sets commonly used for climate research display a large and abrupt increase in Antarctic sea ice area (SIA) in recent years. This unprecedented change of SIA is diagnosed to be primarily caused by an apparent sudden increase in sea ice concentrations within the ice pack, especially in the area of the most-concentrated ice (greater than 95% concentration). A series of alternative satellite-derived records do not display any abnormal sudden SIA changes, but do reveal substantial discrepancies between different satellite sensors and sea ice algorithms. Sea ice concentrations in the central ice pack and SIA values derived from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSRE) are consistently greater than those derived from the Special Sensor Microwave Imager (SSMI). A switch in source data from the SSMI to AMSRE in mid-2009 explains most of the SIA increase in all three affected data sets. If uncorrected for, the discontinuity artificially exaggerates the winter Antarctic SIA increase (1979-2010) by more than a factor of 2 and the spring trend by almost a factor of 4. The discontinuity has a weaker influence on the summer and autumn SIA trends, on calculations of Antarctic sea ice extent, and in the Arctic.

  18. On the Atmospheric Correction of Antarctic Airborne Hyperspectral Data

    Directory of Open Access Journals (Sweden)

    Martin Black

    2014-05-01

    Full Text Available The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4 package reveal absolute reflectance values somewhat in line with laboratory measured spectra, with Root Mean Square Error (RMSE values of 5% in the visible near infrared (0.4–1 µm and 8% in the shortwave infrared (1–2.5 µm. Residual noise remains present due to the absorption by atmospheric gases and aerosols, but certain parts of the spectrum match laboratory measured features very well. This study demonstrates that commercially available packages for carrying out atmospheric correction are capable of correcting airborne hyperspectral data in the challenging environment present in Antarctica. However, it is anticipated that future results from atmospheric correction could be improved by measuring in situ atmospheric data to generate atmospheric profiles and aerosol models, or with the use of multiple ground targets for calibration and validation.

  19. Task-dependent cold stress during expeditions in Antarctic environments.

    Science.gov (United States)

    Morris, Drew M; Pilcher, June J; Powell, Robert B

    2017-01-01

    This study seeks to understand the degree of body cooling, cold perception and physical discomfort during Antarctic tour excursions. Eight experienced expedition leaders across three Antarctic cruise voyages were monitored during occupational tasks: kayaking, snorkelling and zodiac outings. Subjective cold perception and discomfort were recorded using a thermal comfort assessment and skin temperature was recorded using a portable data logger. Indoor cabin temperature and outdoor temperature with wind velocity were used as measures of environmental stress. Physical activity level and clothing insulation were estimated using previous literature. Tour leaders experienced a 6°C (2°C wind chill) environment for an average of 6 hours each day. Leaders involved in kayaking reported feeling colder and more uncomfortable than other leaders, but zodiac leaders showed greater skin temperature cooling. Occupational experience did not predict body cooling or cold stress perception. These findings indicate that occupational cold stress varies by activity and measurement methodology. The current study effectively used objective and subjective measures of cold-stress to identify factors which can contribute to risk in the Antarctic tourism industry. Results suggest that the type of activity may moderate risk of hypothermia, but not discomfort, potentially putting individuals at risk for cognitive related mistakes and cold injuries.

  20. Expanding Antarctic Sea Ice: Anthropogenic or Natural Variability?

    Science.gov (United States)

    Bitz, C. M.

    2016-12-01

    Antarctic sea ice extent has increased over the last 36 years according to the satellite record. Concurrent with Antarctic sea-ice expansion has been broad cooling of the Southern Ocean sea-surface temperature. Not only are Southern Ocean sea ice and SST trends at odds with expectations from greenhouse gas-induced warming, the trend patterns are not reproduced in historical simulations with comprehensive global climate models. While a variety of different factors may have contributed to the observed trends in recent decades, we propose that it is atmospheric circulation changes - and the changes in ocean circulation they induce - that have emerged as the most likely cause of the observed Southern Ocean sea ice and SST trends. I will discuss deficiencies in models that could explain their incorrect response. In addition, I will present results from a series of experiments where the Antarctic sea ice and ocean are forced by atmospheric perturbations imposed within a coupled climate model. Figure caption: Linear trends of annual-mean SST (left) and annual-mean sea-ice concentration (right) over 1980-2014. SST is from NOAA's Optimum Interpolation SST dataset (version 2; Reynolds et al. 2002). Sea-ice concentration is from passive microwave observations using the NASA Team algorithm. Only the annual means are shown here for brevity and because the signal to noise is greater than in the seasonal means. Figure from Armour and Bitz (2015).

  1. Velocities of antarctic outlet glaciers determined from sequential Landsat images

    Science.gov (United States)

    MacDonald, Thomas R.; Ferrigno, Jane G.; Williams, Richard S.; Lucchitta, Baerbel K.

    1989-01-01

    Approximately 91.0 percent of the volume of present-day glacier ice on Earth is in Antarctica; Greenland contains about another 8.3 percent of the volume. Thus, together, these two great ice sheets account for an estimated 99.3 percent of the total. Long-term changes in the volume of glacier ice on our planet are the result of global climate change. Because of the relationship of global ice volume to sea level (± 330 cubic kilometers of glacier ice equals ± 1 millimeter sea level), changes in the mass balance of the antarctic ice sheet are of particular importance.Whether the mass balance of the east and west antarctic ice sheets is positive or negative is not known. Estimates of mass input by total annual precipitation for the continent have been made from scattered meteorological observations (Swithinbank 1985). The magnitude of annual ablation of the ice sheet from calving of outlet glaciers and ice shelves is also not well known. Although the velocities of outlet glaciers can be determined from field measurements during the austral summer,the technique is costly, does not cover a complete annual cycle,and has been applied to just a few glaciers. To increase the number of outlet glaciers in Antarctica for which velocities have been determined and to provide additional data for under-standing the dynamics of the antarctic ice sheets and their response to global climate change, sequential Landsat image of several outlet glaciers were measured.

  2. Searching for novel photolyases in UVC-resistant Antarctic bacteria.

    Science.gov (United States)

    Marizcurrena, Juan José; Morel, María A; Braña, Victoria; Morales, Danilo; Martinez-López, Wilner; Castro-Sowinski, Susana

    2017-03-01

    Ultraviolet (UV) light irradiation has serious consequences for cell survival, including DNA damage by formation of cyclobutane pyrimidine dimers (CPD) and pyrimidine (6,4) pyrimidone photoproducts. In general, the Nucleotide Excision Repair pathway repairs these lesions; however, all living forms, except placental mammals and some marsupials, produce a flavoprotein known as photolyase that directly reverses these lesions. The aim of this work was the isolation and identification of Antarctic UVC-resistant bacteria, and the search for novel photolyases. Two Antarctic water samples were UVC-irradiated (254 nm; 50-200 J m - 2 ) and 12 UVC-resistant bacteria were isolated and identified by 16S rDNA amplification/analysis as members of the genera Pseudomonas, Janthinobacterium, Flavobacterium, Hymenobacter and Sphingomonas. The UVC 50% lethal dose and the photo-repair ability of isolates were analyzed. The occurrence of photolyase coding sequences in Pseudomonas, Hymenobacter and Sphingomonas isolates were searched by PCR or by searching in the draft DNA genome. Results suggest that Pseudomonas and Hymenobacter isolates produce CDP-photolyases, and Sphingomonas produces two CPD-photolyases and a 6,4-photolyase. Results suggest that the Antarctic environment is an important source of genetic material for the identification of novel photolyase genes with potential biotechnological applications.

  3. Preferenční selekce izomeru D-galaktono-1,5-laktonu enzymem .beta.-galaktosidasou z Arthrobacter sp. C2-2 pro vazbu do aktivního místa

    Czech Academy of Sciences Publication Activity Database

    Štěpánková, Andrea; Skálová, Tereza; Dohnálek, Jan; Dušková, Jarmila; Kolenko, Petr; Hašek, Jindřich; Lipovová, P.

    2009-01-01

    Roč. 103, č. 5 (2009), s. 450 ISSN 0009-2770. [Mezioborové setkání mladých biologů, biochemiků a chemiků. Konference Sigma-Aldrich /9./. 26.05.2009-29.05.2009, Devět skal - Žďárské vrchy] R&D Projects: GA ČR GA305/07/1073; GA AV ČR KJB500500512 Institutional research plan: CEZ:AV0Z40500505 Keywords : . beta .- galactosidase Subject RIV: EB - Genetics ; Molecular Biology

  4. Crystallization and preliminary crystallographic analysis of maganese(II)-dependent 2,3-dihydroxybiphenyl 1,2-dioxygenase from Bacillus sp. JF8

    International Nuclear Information System (INIS)

    Senda, Miki; Hatta, Takashi; Kimbara, Kazuhide; Senda, Toshiya

    2010-01-01

    A thermostable manganese(II)-dependent 2,3-dihydroxybiphenyl-1,2-dioxygenase derived from Bacillus sp. JF8 was crystallized in two forms using the sitting-drop vapour-diffusion method. Both crystals diffracted to approximately 1.3 Å resolution. A thermostable manganese(II)-dependent 2,3-dihydroxybiphenyl-1,2-dioxygenase derived from Bacillus sp. JF8 was crystallized. The initial screening for crystallization was performed by the sitting-drop vapour-diffusion method using a crystallization robot, resulting in the growth of two crystal forms. The first crystal belonged to space group P1, with unit-cell parameters a = 62.7, b = 71.4, c = 93.6 Å, α = 71.2, β = 81.0, γ = 64.0°, and diffracted to 1.3 Å resolution. The second crystal belonged to space group I222, with unit-cell parameters a = 74.2, b = 90.8, c = 104.3 Å, and diffracted to 1.3 Å resolution. Molecular-replacement trials using homoprotocatechuate 2,3-dioxygenase from Arthrobacter globiformis (28% amino-acid sequence identity) as a search model provided a satisfactory solution for both crystal forms

  5. Tsukamurella pulmonis sp. nov.

    Science.gov (United States)

    Yassin, A F; Rainey, F A; Brzezinka, H; Burghardt, J; Rifai, M; Seifert, P; Feldmann, K; Schaal, K P

    1996-04-01

    Chemotaxonomic and 16S ribosomal DNA sequence analyses of an isolate from the sputum of a patient with a mycobacterial lung infection clearly delineated a new species of the genus Tsukamurella. This new species can be defined on the basis of genotypic and phenotypic data. The name Tsukamurella pulmonis sp. nov. is proposed for this organism; the type strain is IMMIB D-1321T (= DSM 44142T). This isolate shows 44.2 and 36.2% DNA relatedness to Tsukamurella paurometabola DSM 20162T (T = type strain) and Tsukamurella inchonensis DSM 44067T, respectively.

  6. Parasite fauna of the Antarctic dragonfish Parachaenichthys charcoti (Perciformes: Bathydraconidae) and closely related Bathydraconidae from the Antarctic Peninsula, Southern Ocean.

    Science.gov (United States)

    Münster, Julian; Kochmann, Judith; Grigat, Juline; Klimpel, Sven; Kuhn, Thomas

    2017-05-12

    As members of the Notothenioidei - the dominant fish taxon in Antarctic waters - the family Bathydraconidae includes 12 genera and 17 species. The knowledge of these species inhabiting an isolated environment is rather fragmentary, including their parasite fauna. Studies on fish hosts and their associated parasites can help gain insights into even remote ecosystems and be used to infer ecological roles in food webs; however, ecological studies on the Bathydraconidae are scarce. In this study, stomach contents and parasite fauna of the Antarctic dragonfish species Parachaenichthys charcoti (n = 47 specimens) as well as of Gerlachea australis (n = 5), Gymnodraco acuticeps (n = 9) and Racovitzia glacialis (n = 6) were examined. The parasite fauna of P. charcoti consisted of eight genera represented by 11 species, with three of them being new host records. Overall, 24 parasite genera and 26 species were found in the sampled fish, including eleven new host records. Analyses revealed that the majority of the parasite species found in the different fish hosts are endemic to Antarctic waters and are characterized by a broad host range. These findings are evidence for the current lack of knowledge and the need for further parasitological studies of fish species in this unique habitat.

  7. 76 FR 39905 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-07-07

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and..., Switzerland, and the USA) project examining the effects of climate warming on seasonal thawing, permafrost...

  8. 75 FR 68830 - Notice of permit applications received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-11-09

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... the Ross Sea. Once experiments are concluded, the lysates will be placed in the radioactive waste...

  9. 78 FR 76862 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2013-12-19

    ... the Antarctic Science, Tourism and Conservation Act of 1996, has developed regulations for the... in Antarctic waters. Likewise, the sex of individual whales can be determined from genetic markers...

  10. 75 FR 57299 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-09-20

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... spatial scales of various types of disturbances in and around McMurdo Station, Antarctica. The sampling...

  11. 76 FR 61117 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-10-03

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... and spatial scales of various types of disturbances in and around McMurdo Station. The sampling...

  12. 75 FR 42462 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-07-21

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... accurate maps of areas of important scientific and environmental importance within the Ross Sea region...

  13. 75 FR 57298 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-09-20

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and..., Coulman Island and Cape Roget, and photo/counting census at Cape Washington, including abandoned egg and...

  14. 77 FR 32701 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2012-06-01

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... overriding incentives is to know how best to conserve this great natural resource of the bird, the food...

  15. 78 FR 33115 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2013-06-03

    ... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... pregnancy and future parturition rates; and (3) To what extent might changes in food availability during the...

  16. Law 16.518 Antarctic Treaty: approve the protocols about Environment protection and annex s

    International Nuclear Information System (INIS)

    1994-01-01

    The treaty Antarctic in their appendix C in its articles is about the elimination of residuals by means of its removal of the area of having Treated Antarctic among them radioactive materials, planning of the wastes, communication treatment and exam of the plans of treatment of wastes, treatment proceeding prevention of sea contamination ,discharge of hydrocarbons petroliferous, discharge of liquid noxious substances [es

  17. Food choice of Antarctic soil arthropods clarified by stable isotope signatures

    NARCIS (Netherlands)

    Bokhorst, S.F.; Ronfort, C.; Huiskes, A.H.L.; Convey, P.; Aerts, R.A.M.

    2007-01-01

    Antarctic soil ecosystems are amongst the most simplified on Earth and include only few soil arthropod species, generally believed to be opportunistic omnivorous feeders. Using stable isotopic analyses, we investigated the food choice of two common and widely distributed Antarctic soil arthropod

  18. Standing crop and growth rates of net phytoplankton and nanoplankton in Antarctic waters

    Digital Repository Service at National Institute of Oceanography (India)

    Goes, J.I.; Fondekar, S.P.; Parulekar, A.H.

    stream_size 16 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_419.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_419.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  19. Living resources of Antarctic India's contribution to exploration and future plans for exploration

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.

    stream_size 7 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_459.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_459.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  20. Meltwater produced by wind–albedo interaction stored in an East Antarctic ice shelf

    NARCIS (Netherlands)

    Lenaerts, JTM; Lhermitte, S.L.M.; Drews, R.; Ligtenberg, SRM; Berger, S.; Helm, V.; Smeets, C.J.P.P.; van den Broeke, MR; van de Berg, W.J.; van Meijgaard, E; Eijkelboom, M.; Eisen, O.; Pattyn, F.

    2017-01-01

    Surface melt and subsequent firn air depletion can ultimately lead to disintegration of Antarctic ice shelves1, 2 causing grounded glaciers to accelerate3 and sea level to rise. In the Antarctic Peninsula, foehn winds enhance melting near the grounding line4, which in the recent past has led to the

  1. Contrasting Arctic and Antarctic atmospheric responses to future sea-ice loss

    Science.gov (United States)

    England, M.; Polvani, L. M.; Sun, L.

    2017-12-01

    By the end of this century, the annual mean Antarctic sea ice area is projected to decline by over a third, an amount similar to that in the Arctic, but the effect of Antarctic sea ice loss on the atmosphere remains largely unexplored. Using the Community Earth Systems Model (CESM) Whole Atmosphere Coupled Climate Model (WACCM), we investigate the effect of future Antarctic sea ice loss, and contrast it with its Arctic counterpart. This is accomplished by analyzing integrations of the model with historic and future sea ice levels, using the RCP8.5 scenario. This allows us to disentangle the effect of future sea ice loss on the atmosphere from other aspects of the coupled system. We find that both Antarctic and Arctic sea ice loss act to shift the tropospheric jet equatorwards, counteracting the poleward shift due to increases in greenhouse gases. Although the total forcing to the atmosphere is similar in both hemispheres, the response to Arctic sea ice loss is larger in amplitude and but more seasonally varying, while the response in the Antarctic persists throughout the year but with a smaller amplitude. Furthermore, the atmospheric temperature response over the Antarctic is trapped closer to the surface than in the Arctic, and perhaps surprisingly, we find that the surface temperature response to Antarctic sea ice loss is unable to penetrate the Antarctic continent.

  2. A high-end sea level rise probabilistic projection including rapid Antarctic ice sheet mass loss

    NARCIS (Netherlands)

    Le Bars, D.M.; Drijfhout, S.S.; de Vries, Hylke

    2017-01-01

    The potential for break-up of Antarctic ice shelves by hydrofracturing and following ice cliff instability might be important for future ice dynamics. One recent study suggests that the Antarctic ice sheet could lose a lot more mass during the 21st century than previously thought. This increased

  3. Acetobacter intermedius, sp. nov.

    Science.gov (United States)

    Boesch, C; Trcek, J; Sievers, M; Teuber, M

    1998-03-01

    Strains of a new species in the genus Acetobacter, for which we propose the name A. intermedius sp. nov., were isolated and characterized in pure culture from different sources (Kombucha beverage, cider vinegar, spirit vinegar) and different countries (Switzerland, Slovenia). The isolated strains grow in media with 3% acetic acid and 3% ethanol as does A. europaeus, do, however, not require acetic acid for growth. These characteristics phenotypically position A. intermedius between A. europaeus and A. xylinus, DNA-DNA hybridizations of A. intermedius-DNA with DNA of the type strains of Acetobacter europaeus, A. xylinus, A. aceti, A. hansenii, A. liquefaciens, A. methanolicus, A. pasteurianus, A. diazotrophicus, Gluconobacter oxydans and Escherichia coli HB 101 indicated less than 60% DNA similarity. The important features of the new species are described. Acetobacter intermedius strain TF2 (DSM11804) isolated from the liquid phase of a tea fungus beverage (Kombucha) is the type strain.

  4. Tsukamurella tyrosinosolvens sp. nov.

    Science.gov (United States)

    Yassin, A F; Rainey, F A; Burghardt, J; Brzezinka, H; Schmitt, S; Seifert, P; Zimmermann, O; Mauch, H; Gierth, D; Lux, I; Schaal, K P

    1997-07-01

    Chemotaxonomic and 16S ribosomal DNA sequence analyses of four bacterial isolates from blood cultures from patients with cardiac pacemaker implants and sputa of patients with chronic lung infections clearly demonstrated that these bacteria belong to the genus Tsukamurella. DNA-DNA hybridization data, as well as the physiological characteristics of the isolates, indicate that they are closely related and belong to a single species that differs from previously described members of the genus Tsukamurella. The name Tsukamurella tyrosinosolvens sp. nov. is proposed for these isolates, and the new species is represented by strain IMMIB D-1397T (= DSM 44234T). Strain IMMIB D-1397T exhibits 53.4, 53.5, and 54.7% DNA-DNA relatedness to Tsukamurella paurometabola DSM 20162T, Tsukamurella inchonensis DSM 44067T, and Tsukamurella pulmonis DSM 44142T, respectively.

  5. Zooplankton biomass data collected from net tows from the Eltanin in the Antarctic in support of the US Antarctic Research Program (USARP) from 1963 - 1967 (NODC Accession 0068171)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton biomass data (displacement volume, settled volume) sampled aboard the R/V ELTANIN during the U.S. Antarctic Research Program (USARP) from Apr 5 1963 to...

  6. Climate Change Impacts in the sub-Antarctic Islands Technical Report N.2 of ONERC

    International Nuclear Information System (INIS)

    2009-01-01

    Difficult to apprehend as a whole, the polar regions constitute the Arctic to the North, an ocean surrounded by emerged lands, and the Antarctic to the South, a continent bordered by the Austral Ocean where a belt of sub Antarctic islands lies. Climate change impacts on sub Antarctic islands are varied, direct and indirect: glacier retreat, more favourable conditions for introduced species, marine biodiversity modification, etc. This report discusses the French, British, Australian, South African and New Zealand sub Antarctic islands, the climatic evolutions and the resulting impacts, focused especially on biodiversity. The Observatoire National sur les Effets du Rechauffement Climatique and the International Polar Foundation have been joined in this endeavour by the French polar institute Paul-Emile Victor, the administration of the French Southern and Antarctic Lands (TAAF in French) and the International Union for the Conservation of Nature. (authors)

  7. Climate-dependent evolution of Antarctic ectotherms: An integrative analysis

    Science.gov (United States)

    Pörtner, Hans O.

    2006-04-01

    The paper explores the climate-dependent evolution of marine Antarctic fauna and tries to identify key mechanisms involved as well as the driving forces that have caused the physiological and life history characteristics observed today. In an integrative approach it uses the recent concept of oxygen and capacity limited thermal tolerance to identify potential links between molecular, cellular, whole-organism, and ecological characteristics of marine animal life in the Antarctic. As a generalized pattern, minimization of baseline energy costs, for the sake of maximized growth in the cold, appears as one over-arching principle shaping the evolution and functioning of Antarctic marine ectotherms. This conclusion is supported by recent comparisons with (sub-) Arctic ectotherms, where elevated levels of energy turnover result at unstable, including cold temperatures, and are related to wide windows of thermal tolerance and associated metabolic features. At biochemical levels, metabolic regulation at low temperatures in general, is supported by the cold compensation of enzyme kinetic parameters like substrate affinities and turnover numbers, through minute structural modifications of the enzyme molecule. These involve a shift in protein folding, sometimes supported by the replacement of individual amino acids. The hypothesis is developed that efficient metabolic regulation at low rates in Antarctic marine stenotherms occurs through high mitochondrial densities at low capacities and possibly enhanced levels of Arrhenius activation energies or activation enthalpies. This contrasts the more costly patterns of metabolic regulation at elevated rates in cold-adapted eurytherms. Energy savings in Antarctic ectotherms, largely exemplified in fish, typically involve low-cost, diffusive oxygen distribution due to high density of lipid membranes, loss of haemoglobin, myoglobin and the heat shock response, reduced anaerobic capacity, large myocytes with low ion exchange activities

  8. Atmospheric influences on the anomalous 2016 Antarctic sea ice decay

    Science.gov (United States)

    Schlosser, Elisabeth; Haumann, F. Alexander; Raphael, Marilyn N.

    2018-03-01

    In contrast to the Arctic, where total sea ice extent (SIE) has been decreasing for the last three decades, Antarctic SIE has shown a small, but significant, increase during the same time period. However, in 2016, an unusually early onset of the melt season was observed; the maximum Antarctic SIE was already reached as early as August rather than the end of September, and was followed by a rapid decrease. The decay was particularly strong in November, when Antarctic SIE exhibited a negative anomaly (compared to the 1979-2015 average) of approximately 2 million km2. ECMWF Interim reanalysis data showed that the early onset of the melt and the rapid decrease in sea ice area (SIA) and SIE were associated with atmospheric flow patterns related to a positive zonal wave number three (ZW3) index, i.e., synoptic situations leading to strong meridional flow and anomalously strong southward heat advection in the regions of strongest sea ice decline. A persistently positive ZW3 index from May to August suggests that SIE decrease was preconditioned by SIA decrease. In particular, in the first third of November northerly flow conditions in the Weddell Sea and the Western Pacific triggered accelerated sea ice decay, which was continued in the following weeks due to positive feedback effects, leading to the unusually low November SIE. In 2016, the monthly mean Southern Annular Mode (SAM) index reached its second lowest November value since the beginning of the satellite observations. A better spatial and temporal coverage of reliable ice thickness data is needed to assess the change in ice mass rather than ice area.

  9. [Microbiological analysis of terrestrial biotopes of the Antarctic region].

    Science.gov (United States)

    Tashirev, A B; Romanovskaia, V A; Rokitko, P V; Shilin, S O; Chernaia, N A; Tashireva, A A

    2010-01-01

    Microbiological analysis has been made of 120 samples from biotopes of the western coast of the Antarctic peninsula (Rasmussen cope, Tuxen cope, Waugh mountain), Argentine archipelago islands (Galindez, Skua, Corner, Barchans, Irizar, Uruguay, Cluls, Three Little Pigs, King-George), as well as neighbouring islands (Petermann--on the north, a group of Jalour islands--on the east, Berthelot--on the south-east); and more remote islands (Darboux, Lippmann, Booth). It was found out that the total number of chemoorganotrophic aerobic microorganisms was 10(6) - 10(8) cells/g of soil, that was by 2-3 orders lower than in the regions with temperate climate. One can observe a tendency of decreasing the quantity of chemoorganotrophic microorganisms in the Antartic biotopes (cells/g of a sample) in the following order: soil (1 x 10(7) - 8 x 10(8)), underground part of moss (1 x 10(6) - 5 x 10(7)), grass Deschampsia antarctica (10(6) - 10(8), slit of fresh-water reservoir (10(5) - 10(7)), ground part of moss (10(3) - 10(6)), lichens (10(3) - 10(6)). Representatives of several phylogenetic lines: Proteobacteria (genera Pseudomonas, Methylobacterium, Enterobacter), Firmicutes (genera Bacillus, Staphylococcus), Actinobacteria (genera Brevibacterium, Actinomyces, Streptomyces) have been found in the Antarctic samples. As a rule, genera of bacteria found in the Antarctic Region are widely distributed in different regions of the Earth with temperate climate. Microorganisms similar to the species Exophiala nigra (Issatsch.) Haats et de Hoog 1999, which was first detected 100 years ago by Academician B.L. Isachenko in the Arctic region water, were also isolated from biofilms on vertical rocks of the Galindez Island as well as from the soil of the Irizar Island.

  10. The Last Interglacial History of the Antarctic Ice sheet

    Science.gov (United States)

    Bradley, Sarah; Siddall, Mark; Milne, Glenn A.; Masson-Delmotte, Valerie; Wolff, Eric; Hindmarsh, Richard C. A.

    2014-05-01

    In this paper we present a summary of the work which was conducted as part of the 'PAST4FUTURE -WP4.1: Sea Level and Ice sheets' project. The overall aim of this study was to understand the response of the Antarctic Ice sheet (AIS) to climate forcing during the Last interglacial (LIG) and its contribution to the observed higher than present sea level during this period. The study involved the application and development of a novel technique which combined East Antarctic stable isotope ice core data with the output from a Glacial Isostatic Adjustment (GIA) model [Bradley et al., 2012]. We investigated if the stable isotope ice core data are sensitive to detecting isostatically driven changes in the surface elevation driven by changes in the ice-loading history of the AIS and if so, could we address some key questions relating to the LIG history of the AIS. Although it is believed that the West Antarctic Ice sheet (WAIS) reduced in size during the LIG compared to the Holocene, major uncertainties and unknowns remain unresolved: Did the WAIS collapse? What would the contribution of such a collapse be the higher than present LIG eustatic sea level (ESL)? We will show that a simulated collapse of the WAIS does not generate a significant elevation driven signal at the EAIS LIG ice core sites, and as such, these ice core records cannot be used to assess WAIS stability over this period. However, we will present 'treasure maps' [Bradley et al., 2012] to identify regions of the AIS where results from geological studies and/or new paleoclimate data may be sensitive to detecting a WAIS collapse. These maps can act as a useful tool for the wider science community/field scientists as a guide to highlight sites suitable to constrain the evolution of the WAIS during the LIG. Studies have proposed that the surface temperature across the East Antarctic Ice Sheet (EAIS) was significantly warmer, 2-5°C during the LIG compared to present [Lang and Wolff, 2011]. These higher

  11. Spreading of Antarctic Bottom Water in the Atlantic Ocean

    OpenAIRE

    Morozov, E.; Tarakanov, R. Y.; Zenk, Walter

    2012-01-01

    This paper describes the transport of bottom water from its source region in the Weddell Sea through the abyssal channels of the Atlantic Ocean. The research brings together the recent observations and historical data. A strong flow of Antarctic Bottom Water through the Vema Channel is analyzed. The mean speed of the flow is 30 cm/s. A temperature increase was found in the deep Vema Channel, which has been observed for 30 years already. The flow of bottom water in the northern part of the Bra...

  12. Regeneration of nutrients and biological productivity in Antarctic waters

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.; Somasundar, K.; Qasim, S.Z.

    structure and productivity of Antarctic waters (El-Sayed 1967, Gordon & Goldberg 1970, Deacon 1982). However, detailed studies on the physico-chemical and biological characteristics have been conducted only in a few areas such as the Weddell Sea, Drake... Passage and Scotia Sea (Deacon 1977, El-Sayed &, Taguchi. 1981, Ronner et al. 1983), Ross Sea (Biggs 1982, Smith & Nelson 1985) and some regions of the Indian Ocean SC!ctor (Gambaroni et al. 1982, Le Jahan & Treguer 1985). From these studies it has been...

  13. Full Waveform Adjoint Seismic Tomography of the Antarctic Plate

    Science.gov (United States)

    Lloyd, A. J.; Wiens, D.; Zhu, H.; Tromp, J.; Nyblade, A.; Anandakrishnan, S.; Aster, R. C.; Huerta, A. D.; Winberry, J. P.; Wilson, T. J.; Dalziel, I. W. D.; Hansen, S. E.; Shore, P.

    2017-12-01

    Recent studies investigating the response and influence of the solid Earth on the evolution of the cryosphere demonstrate the need to account for 3D rheological structure to better predict ice sheet dynamics, stability, and future sea level impact, as well as to improve glacial isostatic adjustment models and more accurately measure ice mass loss. Critical rheological properties like mantle viscosity and lithospheric thickness may be estimated from shear wave velocity models that, for Antarctica, would ideally possess regional-scale resolution extending down to at least the base of the transition zone (i.e. 670 km depth). However, current global- and continental-scale seismic velocity models are unable to obtain both the resolution and spatial coverage necessary, do not take advantage of the full set of available Antarctic data, and, in most instance, employ traditional seismic imaging techniques that utilize limited seismogram information. We utilize 3-component earthquake waveforms from almost 300 Antarctic broadband seismic stations and 26 southern mid-latitude stations from 270 earthquakes (5.5 ≤ Mw ≤ 7.0) between 2001-2003 and 2007-2016 to conduct a full-waveform adjoint inversion for Antarctica and surrounding regions of the Antarctic plate. Necessary forward and adjoint wavefield simulations are performed utilizing SPECFEM3D_GLOBE with the aid of the Texas Advanced Computing Center. We utilize phase observations from seismogram segments containing P, S, Rayleigh, and Love waves, including reflections and overtones, which are autonomously identified using FLEXWIN. The FLEXWIN analysis is carried out over a short (15-50 s) and long (initially 50-150 s) period band that target body waves, or body and surface waves, respectively. As our model is iteratively refined, the short-period corner of the long period band is gradually reduced to 25 s as the model converges over 20 linearized inversion iterations. We will briefly present this new high

  14. Program of the Antarctic Syowa MST/IS radar (PANSY)

    Science.gov (United States)

    Sato, Kaoru; Tsutsumi, Masaki; Sato, Toru; Nakamura, Takuji; Saito, Akinori; Tomikawa, Yoshihiro; Nishimura, Koji; Kohma, Masashi; Yamagishi, Hisao; Yamanouchi, Takashi

    2014-10-01

    The PANSY radar is the first Mesosphere-Stratosphere-Troposphere/Incoherent Scatter (MST/IS) radar in the Antarctic region. It is a large VHF monostatic pulse Doppler radar operating at 47 MHz, consisting of an active phased array of 1045 Yagi antennas and an equivalent number of transmit-receive (TR) modules with a total peak output power of 500 kW. The first stage of the radar was installed at Syowa Station (69°00‧S, 39°35‧E) in early 2011, and is currently operating with 228 antennas and modules. This paper reports the project's scientific objectives, technical descriptions, and the preliminary results of observations made to date. The radar is designed to clarify the role of atmospheric gravity waves at high latitudes in the momentum budget of the global circulation in the troposphere, stratosphere and mesosphere, and to explore the dynamical aspects of unique polar phenomena such as polar mesospheric clouds (PMC) and polar stratospheric clouds (PSC). The katabatic winds as a branch of Antarctic tropospheric circulation and as an important source of gravity waves are also of special interest. Moreover, strong and sporadic energy inputs from the magnetosphere by energetic particles and field-aligned currents can be quantitatively assessed by the broad height coverage of the radar which extends from the lower troposphere to the upper ionosphere. From engineering points of view, the radar had to overcome restrictions related to the severe environments of Antarctic research, such as very strong winds, limited power availability, short construction periods, and limited manpower availability. We resolved these problems through the adoption of specially designed class-E amplifiers, light weight and tough antenna elements, and versatile antenna arrangements. Although the radar is currently operating with only about a quarter of its full designed system components, we have already obtained interesting results on the Antarctic troposphere, stratosphere and

  15. The use of Antarctic analogs for the Space Exploration Initiative

    Science.gov (United States)

    Roberts, Barney; Lynch, John T.

    1991-01-01

    Potential approaches to the use of the Antarctic as an analog to the lunar and Mars planetary surface segments of the SEI are reviewed. It is concluded that a well-planned and sustained program of ground-based research and testing in environments analogous to the moon and Mars is a rational method for reducing the risks associated with human space missions. Antarctica may provide an ideal setting for testing critical technologies (habitat design, life support, and advanced scientific instrumentation), studying human factors and physiology, and conducting basic scientific research similar to and directly relevant to that planned for the SEI.

  16. ARM West Antarctic Radiation Experiment (AWARE) Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Lubin, D [National Science Foundation; Bromwich, DH [Ohio State University; Russell, LM [Scripps Institution of Oceanography; Verlinde, J [The Pennsylvania State University; Vogelmann, AM [Brookhaven National Laboratory

    2015-10-01

    West Antarctica is one of the most rapidly warming regions on Earth, and this warming is closely connected with global sea level rise. The discovery of rapid climate change on the West Antarctic Ice Sheet (WAIS) has challenged previous explanations of Antarctic climate change that focused on strengthening of circumpolar westerlies in response to the positive polarity trend in the Southern Annular Mode. West Antarctic warming does not yet have a comprehensive explanation: dynamical mechanisms may vary from one season to the next, and these mechanisms very likely involve complex teleconnections with subtropical and tropical latitudes. The prime motivation for this proposal is that there has been no substantial atmospheric science or climatological field work on West Antarctica since the 1957 International Geophysical Year and that research continued for only a few years. Direct meteorological information on the WAIS has been limited to a few automatic weather stations for several decades, yet satellite imagery and meteorological reanalyses indicate that West Antarctica is highly susceptible to advection of warm and moist maritime air with related cloud cover, depending on the location and strength of low pressure cells in the Amundsen, Ross, and Bellingshausen Seas. There is a need to quantify the role of these changing air masses on the surface energy balance, including all surface energy components and cloud-radiative forcing. More generally, global climate model simulations are known to perform poorly over the Antarctic and Southern Oceans, and the marked scarcity of cloud information at southern high latitudes has so far inhibited significant progress. Fortunately, McMurdo Station, where the Atmospheric Radiation Measurement Facility’s (ARM’s) most advanced cloud and aerosol instrumentation is situated, has a meteorological relationship with the WAIS via circulation patterns in the Ross and Amundsen Seas. We can therefore gather sophisticated data with cloud

  17. Structure and application of antifreeze proteins from Antarctic bacteria.

    Science.gov (United States)

    Muñoz, Patricio A; Márquez, Sebastián L; González-Nilo, Fernando D; Márquez-Miranda, Valeria; Blamey, Jenny M

    2017-08-07

    Antifreeze proteins (AFPs) production is a survival strategy of psychrophiles in ice. These proteins have potential in frozen food industry avoiding the damage in the structure of animal or vegetal foods. Moreover, there is not much information regarding the interaction of Antarctic bacterial AFPs with ice, and new determinations are needed to understand the behaviour of these proteins at the water/ice interface. Different Antarctic places were screened for antifreeze activity and microorganisms were selected for the presence of thermal hysteresis in their crude extracts. Isolates GU1.7.1, GU3.1.1, and AFP5.1 showed higher thermal hysteresis and were characterized using a polyphasic approach. Studies using cucumber and zucchini samples showed cellular protection when samples were treated with partially purified AFPs or a commercial AFP as was determined using toluidine blue O and neutral red staining. Additionally, genome analysis of these isolates revealed the presence of genes that encode for putative AFPs. Deduced amino acids sequences from GU3.1.1 (gu3A and gu3B) and AFP5.1 (afp5A) showed high similarity to reported AFPs which crystal structures are solved, allowing then generating homology models. Modelled proteins showed a triangular prism form similar to β-helix AFPs with a linear distribution of threonine residues at one side of the prism that could correspond to the putative ice binding side. The statistically best models were used to build a protein-water system. Molecular dynamics simulations were then performed to compare the antifreezing behaviour of these AFPs at the ice/water interface. Docking and molecular dynamics simulations revealed that gu3B could have the most efficient antifreezing behavior, but gu3A could have a higher affinity for ice. AFPs from Antarctic microorganisms GU1.7.1, GU3.1.1 and AFP5.1 protect cellular structures of frozen food showing a potential for frozen food industry. Modeled proteins possess a β-helix structure, and

  18. Obliquity-paced Pliocene West Antarctic ice sheet oscillations

    Science.gov (United States)

    Naish, T.; Powell, R.; Levy, R.; Wilson, G.; Scherer, R.; Talarico, F.; Krissek, L.; Niessen, F.; Pompilio, M.; Wilson, T.; Carter, L.; DeConto, R.; Huybers, P.; McKay, R.; Pollard, D.; Ross, J.; Winter, D.; Barrett, P.; Browne, G.; Cody, R.; Cowan, E.; Crampton, J.; Dunbar, G.; Dunbar, N.; Florindo, F.; Gebhardt, C.; Graham, I.; Hannah, M.; Hansaraj, D.; Harwood, D.; Helling, D.; Henrys, S.; Hinnov, L.; Kuhn, G.; Kyle, P.; Laufer, A.; Maffioli, P.; Magens, D.; Mandernack, K.; McIntosh, W.; Millan, C.; Morin, R.; Ohneiser, C.; Paulsen, T.; Persico, D.; Raine, I.; Reed, J.; Riesselman, C.; Sagnotti, L.; Schmitt, D.; Sjunneskog, C.; Strong, P.; Taviani, M.; Vogel, S.; Wilch, T.; Williams, T.

    2009-01-01

    Thirty years after oxygen isotope records from microfossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth's orbital geometry control the ice ages1, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles2. Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the 'warmer-than-present' early-Pliocene epoch (5–3 Myr ago) is needed to better constrain the possible range of ice-sheet behaviour in the context of future global warming3. Here we present a marine glacial record from the upper 600 m of the AND-1B sediment core recovered from beneath the northwest part of the Ross ice shelf by the ANDRILL programme and demonstrate well-dated, 40-kyr cyclic variations in ice-sheet extent linked to cycles in insolation influenced by changes in the Earth's axial tilt (obliquity) during the Pliocene. Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to 3 °C warmer than today4 and atmospheric CO2 concentration was as high as 400 p.p.m.v. (refs 5, 6). The evidence is consistent with a new ice-sheet/ice-shelf model7 that simulates fluctuations in Antarctic ice volume of up to +7 m in equivalent sea level associated with the loss of the WAIS and up to +3 m in equivalent sea level from the East Antarctic ice sheet, in response to ocean-induced melting paced by obliquity. During interglacial times, diatomaceous sediments indicate high surface-water productivity, minimal summer sea ice and air temperatures above freezing, suggesting an additional influence of surface melt8 under conditions of elevated CO2.

  19. Organic carbon in Antarctic snow: spatial trends and possible sources

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, R.; Mahalinganathan, K.; Thamban, M.; Nair, S.

    ,J.;vonGlasgow,R.;Weller,R.;Wolff,E.;Zhu,T.Anoverviewof snow photochemistry: Evidence, mechanisms and impacts. Atmos. Chem. Phys. 2007, 7, 4329–4373. (6) Priscu, J. C.; et al. Antarctic subglacial water: Origin, evolution, and ecology. In Polar Lakes and Rivers; Vincent, W. F., Laybourn-Parry, J., Eds...) Jaenicke, R. Atmospheric aerosols and global climate. J. Aerosol Sci. 1980, 11, 577–588. (26) Hodson, A.; Anesio, A. M.; Tranter, M.; Fountain, A.; Osborn, M.; Priscu, J.; Laybourn-Parry, J.; Sattler, B. Glacial ecosystems. Ecol. Monogr. 2008, 78 (1), 41...

  20. Arctic, Antarctic, and temperate green algae Zygnema spp. under UV-B stress: vegetative cells perform better than pre-akinetes.

    Science.gov (United States)

    Holzinger, Andreas; Albert, Andreas; Aigner, Siegfried; Uhl, Jenny; Schmitt-Kopplin, Philippe; Trumhová, Kateřina; Pichrtová, Martina

    2018-02-22

    Species of Zygnema form macroscopically visible mats in polar and temperate terrestrial habitats, where they are exposed to environmental stresses. Three previously characterized isolates (Arctic Zygnema sp. B, Antarctic Zygnema sp. C, and temperate Zygnema sp. S) were tested for their tolerance to experimental UV radiation. Samples of young vegetative cells (1 month old) and pre-akinetes (6 months old) were exposed to photosynthetically active radiation (PAR, 400-700 nm, 400 μmol photons m -2  s -1 ) in combination with experimental UV-A (315-400 nm, 5.7 W m -2 , no UV-B), designated as PA, or UV-A (10.1 W m -2 ) + UV-B (280-315 nm, 1.0 W m -2 ), designated as PAB. The experimental period lasted for 74 h; the radiation period was 16 h PAR/UV-A per day, or with additional UV-B for 14 h per day. The effective quantum yield, generally lower in pre-akinetes, was mostly reduced during the UV treatment, and recovery was significantly higher in young vegetative cells vs. pre-akinetes during the experiment. Analysis of the deepoxidation state of the xanthophyll-cycle pigments revealed a statistically significant (p UV-absorbing phenolic compounds was significantly higher (p UV-B stress than pre-akinetes.

  1. Bradysia sp. em morangueiro Bradysia sp. in strawberry

    Directory of Open Access Journals (Sweden)

    Bernadete Radin

    2009-04-01

    Full Text Available No trabalho, relatam-se os primeiros registros de Bradysia sp. (Insecta: Diptera: Sciaridae em morangueiro (Fragaria x ananassa Duch., cultivado no Município de Eldorado do Sul, RS. O cultivo foi realizado em sacolas com três metros de comprimento, preenchidas com substrato composto de casca de arroz e turfa, dispostas horizontalmente sobre bancadas de madeira, em ambiente protegido. A presença de Bradysia sp. foi observada na segunda quinzena de agosto de 2005. Neste trabalho, estão descritos os sintomas apresentados no morangueiro pela praga, prováveis conseqüências sobre o aparecimento de doenças e uma breve descrição morfológica da Bradysia sp., adulto e fase larval.This paper describes the first record of Bradysia sp. (Insecta; Diptera; Sciaridae in strawberry (Fragaria x ananassa, cultivated in the city of Eldorado do Sul, RS, Brazil. Strawberry was planted in plastic bags filled with a mixture of burnt rice hulls and peat and cultivated in a greenhouse. The presence of Bradysia sp was noticed in the second fortnight of August, 2005. The symptoms in strawberry and the probable consequences in terms of disease arising were described in the present study, as well as the morphological characterization of Bradysia sp. and its illustrations.

  2. SP-100 reactor design

    International Nuclear Information System (INIS)

    Armijo, J.S.; Atwell, J.; Pluta, P.R.; Smith, M.A.; Solorzano, E.R.

    1987-01-01

    The SP-100 space reactor power system is being designed and developed as part of the Ground Engineering System (GES) contract between General Electric Company as the system developer and the Department of Energy. Other key participants in the GES program include Westinghouse Hanford Company (site operator), Los Alamos National Laboratory (fuel development and production), Oak Ridge National Laboratory (materials), and Westinghouse, Advanced Energy Systems Division (shield, HTS equipment). The GES Program includes two major elements. First, the development of a Reference Flight System design at 100 kWe output to the user, and second the validation of the Reference Flight System design by analysis and by testing. Development of key technologies along with component and system testing is an essential part of the validation program. The nuclear subsystem validation includes the design, manufacture, assembly and operational testing of a Ground Reactor Test Assembly. The subject of this paper is the reactor design for the Reference Flight System. The reference flight design is in the preliminary design stage and will evolve over the next year

  3. On the Size of the Antarctic Ozone Hole

    Science.gov (United States)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph

    2002-01-01

    The Antarctic ozone hole is a region of extremely large ozone depletion that is roughly centered over the South Pole. Since 1979, the area coverage of the ozone hole has grown from near zero size to over 24 Million sq km. In the 8-year period from 1981 to 1989, the area expanded by 18 Million sq km. During the last 5 years, the hole has been observed to exceed 25 Million sq km over brief periods. In the spring of 2002, the size of the ozone hole barely reached 20 Million sq km for only a couple of days. We will review these size observations, the size trends, and the interannual variability of the size. The area is derived from the area enclosed by the 220 DU total ozone contour. We will discuss the rationale for the choice of 220 DU: 1) it is located near the steep gradient between southern mid-latitudes and the polar region, and 2) 220 DU is a value that is lower than the pre-1979 ozone observations over Antarctica during the spring period. The phenomenal growth of the ozone hole was directly caused by the increases of chlorine and bromine compounds in the stratosphere. In this talk, we will show the relationship of the ozone hole's size to the interannual variability of Antarctic spring temperatures. In addition, we will show the relationship of these same temperatures to planetary-scale wave forcings.

  4. Detecting the Recovery of the Antarctic Ozone Hole

    Science.gov (United States)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Steve

    2004-01-01

    The Antarctic ozone hole develops each year and culminates by early Spring. Antarctic ozone values have been monitored since 1979 using satellite observations from the TOMS instrument. The severity of the hole has been assessed from TOMS using the minimum total ozone value from the October monthly mean (depth of the hole) and by calculating the average size during the September-October period. Ozone is mainly destroyed by halogen catalytic cycles, and these losses are modulated by temperature variations in the collar of the polar lower stratospheric vortex. In this presentation, we show the relationships of halogens and temperature to both the size and depth of the hole. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Using projections of halogen levels combined with age-of-air estimates, we find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. We will show estimates of both when the ozone hole will begin to show first signs of recovery, and when the hole will fully recover to pre-1980 levels.

  5. What Controls the Size of the Antarctic Ozone Hole?

    Science.gov (United States)

    Bhartia, P. K. (Technical Monitor); Newman, Paul A.; Kawa, S. Randolph; Nash, Eric R.

    2002-01-01

    The Antarctic ozone hole is a region of extremely large ozone depletion that is roughly centered over the South Pole. Since 1979, the area coverage of the ozone hole has grown from near zero size to over 24 Million square kilometers. In the 8-year period from 1981 to 1989, the area expanded by 18 Million square kilometers. During the last 5 years, the hole has been observed to exceed 25 Million square kilometers over brief periods. We will review these size observations, the size trends, and the interannual variability of the size. The area is derived from the area enclosed by the 220 DU total ozone contour. We will discuss the rationale for the choice of 220 DU: 1) it is located near the steep gradient between southern mid-latitudes and the polar region, and 2) 220 DU is a value that is lower than the pre- 1979 ozone observations over Antarctica during the spring period. The phenomenal growth of the ozone hole was directly caused by the increases of chlorine and bromine compounds in the stratosphere. In this talk, we will show the relationship of the ozone hole's size to the interannual variability of Antarctic spring temperatures. In addition, we will show the relationship of these same temperatures to planetary-scale wave forcings.

  6. ARM West Antarctic Radiation Experiment (AWARE) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Lubin, Daniel [Univ. of California, San Diego, CA (United States). Scripps Inst. of Oceanography; Bromwich, David H [Ohio State University; Vogelmann, Andrew M [Brookhaven National Lab. (BNL), Upton, NY (United States); Verlinde, Johannes [Pennsylvania State Univ., University Park, PA (United States); Russell, Lynn M [Univ. of California, San Diego, CA (United States). Scripps Inst. of Oceanography

    2017-09-15

    The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE) is the most technologically advanced atmospheric and climate science campaign yet fielded in Antarctica. AWARE was motivated be recent concern about the impact of cryospheric mass loss on global sea level rise. Specifically, the West Antarctic Ice Sheet (WAIS) is now the second largest contributor to rising sea level, after the Greenland Ice Sheet. As steadily warming ocean water erodes the grounding lines of WAIS components where they meet the Amundsen and Bellingshausen Seas, the retreating grounding lines moving inland and downslope on the underlying terrain imply mechanical instability of the entire WAIS. There is evidence that this point of instability may have already been reached, perhaps signifying more rapid loss of WAIS ice mass. At the same time, the mechanical support provided by adjacent ice shelves, and also the fundamental stability of exposed ice cliffs at the ice sheet grounding lines, will be adversely impacted by a warming atmosphere that causes more frequent episodes of surface melting. The surface meltwater damages the ice shelves and ice cliffs through hydrofracturing. With the increasing concern regarding these rapid cryospheric changes, AWARE was motivated by the need to (a) diagnose the surface energy balance in West Antarctica as related to both summer season climatology and potential surface melting, and (b) improve global climate model (GCM) performance over Antarctica, such that future cryospheric projections can be more reliable.

  7. Climate change drives expansion of Antarctic ice-free habitat.

    Science.gov (United States)

    Lee, Jasmine R; Raymond, Ben; Bracegirdle, Thomas J; Chadès, Iadine; Fuller, Richard A; Shaw, Justine D; Terauds, Aleks

    2017-07-06

    Antarctic terrestrial biodiversity occurs almost exclusively in ice-free areas that cover less than 1% of the continent. Climate change will alter the extent and configuration of ice-free areas, yet the distribution and severity of these effects remain unclear. Here we quantify the impact of twenty-first century climate change on ice-free areas under two Intergovernmental Panel on Climate Change (IPCC) climate forcing scenarios using temperature-index melt modelling. Under the strongest forcing scenario, ice-free areas could expand by over 17,000 km 2 by the end of the century, close to a 25% increase. Most of this expansion will occur in the Antarctic Peninsula, where a threefold increase in ice-free area could drastically change the availability and connectivity of biodiversity habitat. Isolated ice-free areas will coalesce, and while the effects on biodiversity are uncertain, we hypothesize that they could eventually lead to increasing regional-scale biotic homogenization, the extinction of less-competitive species and the spread of invasive species.

  8. Impact of Antarctic mixed-phase clouds on climate.

    Science.gov (United States)

    Lawson, R Paul; Gettelman, Andrew

    2014-12-23

    Precious little is known about the composition of low-level clouds over the Antarctic Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. We modify the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm(-2), and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the Antarctic continent. The simulations show significant net CRE over the Southern Ocean storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. These sensitivity tests confirm that Southern Ocean CREs are strongly sensitive to mixed-phase clouds colder than -20 °C.

  9. Proteorhodopsin-bearing bacteria in Antarctic sea ice.

    Science.gov (United States)

    Koh, Eileen Y; Atamna-Ismaeel, Nof; Martin, Andrew; Cowie, Rebecca O M; Beja, Oded; Davy, Simon K; Maas, Elizabeth W; Ryan, Ken G

    2010-09-01

    Proteorhodopsins (PRs) are widespread bacterial integral membrane proteins that function as light-driven proton pumps. Antarctic sea ice supports a complex community of autotrophic algae, heterotrophic bacteria, viruses, and protists that are an important food source for higher trophic levels in ice-covered regions of the Southern Ocean. Here, we present the first report of PR-bearing bacteria, both dormant and active, in Antarctic sea ice from a series of sites in the Ross Sea using gene-specific primers. Positive PR sequences were generated from genomic DNA at all depths in sea ice, and these sequences aligned with the classes Alphaproteobacteria, Gammaproteobacteria, and Flavobacteria. The sequences showed some similarity to previously reported PR sequences, although most of the sequences were generally distinct. Positive PR sequences were also observed from cDNA reverse transcribed from RNA isolated from sea ice samples. This finding indicates that these sequences were generated from metabolically active cells and suggests that the PR gene is functional within sea ice. Both blue-absorbing and green-absorbing forms of PRs were detected, and only a limited number of blue-absorbing forms were found and were in the midsection of the sea ice profile in this study. Questions still remain regarding the protein's ecological functions, and ultimately, field experiments will be needed to establish the ecological and functional role of PRs in the sea ice ecosystem.

  10. Leadership in politics and science within the Antarctic Treaty

    Directory of Open Access Journals (Sweden)

    John R. Dudeney

    2012-04-01

    Full Text Available For over 50 years the Antarctic has been governed through the Antarctic Treaty, an international agreement now between 49 nations of whom 28 Consultative Parties (CPs undertake the management role. Ostensibly, these Parties have qualified for their position on scientific grounds, though diplomacy also plays a major role. This paper uses counts of policy papers and science publications to assess the political and scientific outputs of all CPs over the last 18 years. We show that a subset of the original 12 Treaty signatories, consisting of the seven claimant nations, the USA and Russia, not only set the political agenda for the continent but also provide most of the science, with those CPs producing the most science generally having the greatest political influence. None of the later signatories to the Treaty appear to play a major role in managing Antarctica compared with this group, with half of all CPs collectively producing only 7% of the policy papers. Although acceptance as a CP requires demonstration of a substantial scientific programme, the Treaty has no formal mechanism to review whether a CP continues to meet this criterion. As a first step to addressing this deficiency, we encourage the CPs collectively to resolve to hold regular international peer reviews of their individual science programmes and to make the results available to the other CPs.

  11. Use of antarctic analogs to support the space exploration initiative

    Science.gov (United States)

    Wharton, Robert; Roberts, Barney; Chiang, Erick; Lynch, John; Roberts, Carol; Buoni, Corinne; Andersen, Dale

    1990-01-01

    This report has discussed the Space Exploration Initiative (SEI) and the U.S. Antarctic Program (USAP) in the context of assessing the potential rationale and strategy for conducting a cooperative NASA/NSF (National Science Foundation) effort. Specifically, such an effort would address shared research and data on living and conducting scientific research in isolated, confined, hostile, and remote environments. A review of the respective goals and requirements of NASA and the NSF indicates that numerous opportunities exist to mutually benefit from sharing relevant technologies, data, and systems. Two major conclusions can be drawn: (1) The technologies, experience, and capabilities existing and developing in the aerospace community would enhance scientific research capabilities and the efficiency and effectiveness of operations in Antarctica. The transfer and application of critical technologies (e.g., power, waste management, life support) and collaboration on crew research needs (e.g., human behavior and medical support needs) would streamline the USAP operations and provide the scientific community with advancements in facilities and tools for Antarctic research. (2) Antarctica is the most appropriate earth analog for the environments of the the Moon and Mars. Using Antarctica in this way would contribute substantially to near- and long-term needs and plans for the SEI. Antarctica is one of the few ground-based analogs that would permit comprehensive and integrated studies of three areas deemed critical to productive and safe operations on the Moon and Mars: human health and productivity; innovative scientific research techniques; and reliable, efficient technologies and facilities.

  12. Testing a Mars science outpost in the Antarctic dry valleys

    Science.gov (United States)

    Andersen, D. T.; Mckay, C. P.; Wharton, R. A.; Rummel, J. D.

    1992-01-01

    Field research conducted in the Antarctic has been providing insights about the nature of Mars in the science disciplines of exobiology and geology. Located in the McMurdo Dry Valleys of southern Victoria Land (160 deg and 164 deg E longitude and 76 deg 30 min and 78 deg 30 min S latitude), research outposts are inhabited by teams of 4-6 scientists. It is proposed that the design of these outposts be expanded to enable meaningful tests of many of the systems that will be needed for the successful conduct of exploration activities on Mars. Although there are some important differences between the environment in the Antarctic dry valleys and on Mars, the many similarities and particularly the field science activities, make the dry valleys a useful terrestrial analog to conditions on Mars. Three areas have been identified for testing at a small science outpost in the dry valleys: (1) studying human factors and physiology in an isolated environment; (2) testing emerging technologies (e.g. innovative power management systems, advanced life support facilities including partial bioregenerative life support systems for water recycling and food growth, telerobotics, etc.); and (3) conducting basic scientific research that will enhance understanding of Mars while contributing to the planning for human exploration. It is suggested that an important early result of a Mars habitat program will be the experience gained by interfacing humans and their supporting technology in a remote and stressful environment.

  13. Climate change drives expansion of Antarctic ice-free habitat

    Science.gov (United States)

    Lee, Jasmine R.; Raymond, Ben; Bracegirdle, Thomas J.; Chadès, Iadine; Fuller, Richard A.; Shaw, Justine D.; Terauds, Aleks

    2017-07-01

    Antarctic terrestrial biodiversity occurs almost exclusively in ice-free areas that cover less than 1% of the continent. Climate change will alter the extent and configuration of ice-free areas, yet the distribution and severity of these effects remain unclear. Here we quantify the impact of twenty-first century climate change on ice-free areas under two Intergovernmental Panel on Climate Change (IPCC) climate forcing scenarios using temperature-index melt modelling. Under the strongest forcing scenario, ice-free areas could expand by over 17,000 km2 by the end of the century, close to a 25% increase. Most of this expansion will occur in the Antarctic Peninsula, where a threefold increase in ice-free area could drastically change the availability and connectivity of biodiversity habitat. Isolated ice-free areas will coalesce, and while the effects on biodiversity are uncertain, we hypothesize that they could eventually lead to increasing regional-scale biotic homogenization, the extinction of less-competitive species and the spread of invasive species.

  14. Observation Impact over the Antarctic During the Concordiasi Field Campaign

    Science.gov (United States)

    Boullot, Nathalie; Rabier, Florence; Langland, Rolf; Gelaro, Ron; Cardinali, Carla; Guidard, Vincent; Bauer, Peter; Doerenbecher, Alexis

    2014-01-01

    The impact of observations on analysis uncertainty and forecast performance was investigated for Austral Spring 2010 over the Southern polar area for four different systems (NRL, GMAO, ECMWF and Meteo-France), at the time of the Concordiasi field experiment. The largest multi model variance in 500 hPa height analyses is found in the southern sub-Antarctic oceanic region, where there are strong atmospheric dynamics, rapid forecast error growth, and fewer upper air wind observation data to constrain the analyses. In terms of data impact the most important observation components are shown to be AMSU, IASI, AIRS, GPS-RO, radiosonde, surface and atmospheric motion vector observations. For sounding data, radiosondes and dropsondes, one can note a large impact of temperature at low levels and a large impact of wind at high levels. Observing system experiments using the Concordiasi dropsondes show a large impact of the observations over the Antarctic plateau extending to lower latitudes with the forecast range, with a large impact around 50 to 70deg South. These experiments indicate there is a potential benefit of better using radiance data over land and sea-ice and innovative atmospheric motion vectors obtained from a combination of various satellites to fill the current data gaps and improve NWP in this region.

  15. Antarctic marine sediments as fingerprints of pollution migration

    International Nuclear Information System (INIS)

    Waheed, S.; Ahmad, S.; Rahman, A.; Qureshi, I.H.

    2001-01-01

    Forty elements in 21 coastal marine sediment samples collected during the second Antarctic scientific expedition from 18 different sites of Brekilen area located at the coast of Antarctica were analysed by instrumental neutron activation analysis (INAA) to detect eventual pollution. Radio-assay schemes for three sets of elements after neutron irradiation and cooling were evolved to avoid matrix effects. Data have been compared with those for sediments of various stations at Antarctica and two other regions in different continents. Lower concentration of certain elements in the Antarctic sediments reflects less environmental exposition. Enrichment factors (EF) were calculated for all the elements using the earth crust as reference matrix, based on elemental values by MASON, TAYLOR and WEDEPOHL which show a normal pattern near to unity expect for Ag and Br. The data obtained could also serve as a reference point from which changes in the global environment can be studied. The quality assurance of data was performed using standard reference materials (SRMs) of a similar matrix (IAEA Marine Sediment SD-M/TM and Chinese Marine Sediment GBW 07313). (author)

  16. Genetic signature of Last Glacial Maximum regional refugia in a circum-Antarctic sea spider

    Science.gov (United States)

    Soler-Membrives, Anna; Linse, Katrin; Miller, Karen J.; Arango, Claudia P.

    2017-10-01

    The evolutionary history of Antarctic organisms is becoming increasingly important to understand and manage population trajectories under rapid environmental change. The Antarctic sea spider Nymphon australe, with an apparently large population size compared with other sea spider species, is an ideal target to look for molecular signatures of past climatic events. We analysed mitochondrial DNA of specimens collected from the Antarctic continent and two Antarctic islands (AI) to infer past population processes and understand current genetic structure. Demographic history analyses suggest populations survived in refugia during the Last Glacial Maximum. The high genetic diversity found in the Antarctic Peninsula and East Antarctic (EA) seems related to multiple demographic contraction-expansion events associated with deep-sea refugia, while the low genetic diversity in the Weddell Sea points to a more recent expansion from a shelf refugium. We suggest the genetic structure of N. australe from AI reflects recent colonization from the continent. At a local level, EA populations reveal generally low genetic differentiation, geographically and bathymetrically, suggesting limited restrictions to dispersal. Results highlight regional differences in demographic histories and how these relate to the variation in intensity of glaciation-deglaciation events around Antarctica, critical for the study of local evolutionary processes. These are valuable data for understanding the remarkable success of Antarctic pycnogonids, and how environmental changes have shaped the evolution and diversification of Southern Ocean benthic biodiversity.

  17. Contrasting time trends of organic contaminants in Antarctic pelagic and benthic food webs.

    Science.gov (United States)

    van den Brink, Nico W; Riddle, Martin J; van den Heuvel-Greve, Martine; van Franeker, Jan Andries

    2011-01-01

    We demonstrate that pelagic Antarctic seabirds show significant decreases in concentrations of some persistent organic pollutants. Trends in Adélie penguins and Southern fulmars fit in a general pattern revealed by a broad literature review. Downward trends are also visible in pelagic fish, contrasting sharply with steady or increasing concentrations in Antarctic benthic organisms. Transfer of contaminants between Antarctic pelagic and benthic food webs is associated with seasonal sea-ice dynamics which may influence the balance between the final receptors of contaminants under different climatic conditions. This complicates the predictability of future trends of emerging compounds in the Antarctic ecosystem, such as of the brominated compounds that we detected in Antarctic petrels. The discrepancy in trends between pelagic and benthic organisms shows that Antarctic biota are still final receptors of globally released organic contaminants and it remains questionable whether the total environmental burden of contaminants in the Antarctic ecosystem is declining. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Antarctic glaciation caused ocean circulation changes at the Eocene-Oligocene transition.

    Science.gov (United States)

    Goldner, A; Herold, N; Huber, M

    2014-07-31

    Two main hypotheses compete to explain global cooling and the abrupt growth of the Antarctic ice sheet across the Eocene-Oligocene transition about 34 million years ago: thermal isolation of Antarctica due to southern ocean gateway opening, and declining atmospheric CO2 (refs 5, 6). Increases in ocean thermal stratification and circulation in proxies across the Eocene-Oligocene transition have been interpreted as a unique signature of gateway opening, but at present both mechanisms remain possible. Here, using a coupled ocean-atmosphere model, we show that the rise of Antarctic glaciation, rather than altered palaeogeography, is best able to explain the observed oceanographic changes. We find that growth of the Antarctic ice sheet caused enhanced northward transport of Antarctic intermediate water and invigorated the formation of Antarctic bottom water, fundamentally reorganizing ocean circulation. Conversely, gateway openings had much less impact on ocean thermal stratification and circulation. Our results support available evidence that CO2 drawdown--not gateway opening--caused Antarctic ice sheet growth, and further show that these feedbacks in turn altered ocean circulation. The precise timing and rate of glaciation, and thus its impacts on ocean circulation, reflect the balance between potentially positive feedbacks (increases in sea ice extent and enhanced primary productivity) and negative feedbacks (stronger southward heat transport and localized high-latitude warming). The Antarctic ice sheet had a complex, dynamic role in ocean circulation and heat fluxes during its initiation, and these processes are likely to operate in the future.

  19. Are Antarctic minke whales unusually abundant because of 20th century whaling?

    Science.gov (United States)

    Ruegg, Kristen C; Anderson, Eric C; Scott Baker, C; Vant, Murdoch; Jackson, Jennifer A; Palumbi, Stephen R

    2010-01-01

    Severe declines in megafauna worldwide illuminate the role of top predators in ecosystem structure. In the Antarctic, the Krill Surplus Hypothesis posits that the killing of more than 2 million large whales led to competitive release for smaller krill-eating species like the Antarctic minke whale. If true, the current size of the Antarctic minke whale population may be unusually high as an indirect result of whaling. Here, we estimate the long-term population size of the Antarctic minke whale prior to whaling by sequencing 11 nuclear genetic markers from 52 modern samples purchased in Japanese meat markets. We use coalescent simulations to explore the potential influence of population substructure and find that even though our samples are drawn from a limited geographic area, our estimate reflects ocean-wide genetic diversity. Using Bayesian estimates of the mutation rate and coalescent-based analyses of genetic diversity across loci, we calculate the long-term population size of the Antarctic minke whale to be 670,000 individuals (95% confidence interval: 374,000-1,150,000). Our estimate of long-term abundance is similar to, or greater than, contemporary abundance estimates, suggesting that managing Antarctic ecosystems under the assumption that Antarctic minke whales are unusually abundant is not warranted.

  20. Air-sea interaction regimes in the sub-Antarctic Southern Ocean and Antarctic marginal ice zone revealed by icebreaker measurements

    Science.gov (United States)

    Yu, Lisan; Jin, Xiangze; Schulz, Eric W.; Josey, Simon A.

    2017-08-01

    This study analyzed shipboard air-sea measurements acquired by the icebreaker Aurora Australis during its off-winter operation in December 2010 to May 2012. Mean conditions over 7 months (October-April) were compiled from a total of 22 ship tracks. The icebreaker traversed the water between Hobart, Tasmania, and the Antarctic continent, providing valuable in situ insight into two dynamically important, yet poorly sampled, regimes: the sub-Antarctic Southern Ocean and the Antarctic marginal ice zone (MIZ) in the Indian Ocean sector. The transition from the open water to the ice-covered surface creates sharp changes in albedo, surface roughness, and air temperature, leading to consequential effects on air-sea variables and fluxes. Major effort was made to estimate the air-sea fluxes in the MIZ using the bulk flux algorithms that are tuned specifically for the sea-ice effects, while computing the fluxes over the sub-Antarctic section using the COARE3.0 algorithm. The study evidenced strong sea-ice modulations on winds, with the southerly airflow showing deceleration (convergence) in the MIZ and acceleration (divergence) when moving away from the MIZ. Marked seasonal variations in heat exchanges between the atmosphere and the ice margin were noted. The monotonic increase in turbulent latent and sensible heat fluxes after summer turned the MIZ quickly into a heat loss regime, while at the same time the sub-Antarctic surface water continued to receive heat from the atmosphere. The drastic increase in turbulent heat loss in the MIZ contrasted sharply to the nonsignificant and seasonally invariant turbulent heat loss over the sub-Antarctic open water.Plain Language SummaryThe icebreaker Aurora Australis is a research and supply vessel that is regularly chartered by the Australian Antarctic Division during the southern summer to operate in waters between Hobart, Tasmania, and Antarctica. The vessel serves as the main lifeline to three permanent research stations on the

  1. Two Antarctic penguin genomes reveal insights into their evolutionary history and molecular changes related to the Antarctic environment.

    Science.gov (United States)

    Li, Cai; Zhang, Yong; Li, Jianwen; Kong, Lesheng; Hu, Haofu; Pan, Hailin; Xu, Luohao; Deng, Yuan; Li, Qiye; Jin, Lijun; Yu, Hao; Chen, Yan; Liu, Binghang; Yang, Linfeng; Liu, Shiping; Zhang, Yan; Lang, Yongshan; Xia, Jinquan; He, Weiming; Shi, Qiong; Subramanian, Sankar; Millar, Craig D; Meader, Stephen; Rands, Chris M; Fujita, Matthew K; Greenwold, Matthew J; Castoe, Todd A; Pollock, David D; Gu, Wanjun; Nam, Kiwoong; Ellegren, Hans; Ho, Simon Yw; Burt, David W; Ponting, Chris P; Jarvis, Erich D; Gilbert, M Thomas P; Yang, Huanming; Wang, Jian; Lambert, David M; Wang, Jun; Zhang, Guojie

    2014-01-01

    Penguins are flightless aquatic birds widely distributed in the Southern Hemisphere. The distinctive morphological and physiological features of penguins allow them to live an aquatic life, and some of them have successfully adapted to the hostile environments in Antarctica. To study the phylogenetic and population history of penguins and the molecular basis of their adaptations to Antarctica, we sequenced the genomes of the two Antarctic dwelling penguin species, the Adélie penguin [Pygoscelis adeliae] and emperor penguin [Aptenodytes forsteri]. Phylogenetic dating suggests that early penguins arose ~60 million years ago, coinciding with a period of global warming. Analysis of effective population sizes reveals that the two penguin species experienced population expansions from ~1 million years ago to ~100 thousand years ago, but responded differently to the climatic cooling of the last glacial period. Comparative genomic analyses with other available avian genomes identified molecular changes in genes related to epidermal structure, phototransduction, lipid metabolism, and forelimb morphology. Our sequencing and initial analyses of the first two penguin genomes provide insights into the timing of penguin origin, fluctuations in effective population sizes of the two penguin species over the past 10 million years, and the potential associations between these biological patterns and global climate change. The molecular changes compared with other avian genomes reflect both shared and diverse adaptations of the two penguin species to the Antarctic environment.

  2. The experience of the Antarctic Seismic Data Library System (SDLS) as a hub for researchers in antarctic crustal studies.

    Science.gov (United States)

    Diviacco, Paolo; Wardell, Nigel

    2010-05-01

    The SDLS was created in April 1991 under the auspices of the Scientific Committee on Antarctic Research to provide open access to Antarctic multichannel seismic-reflection data (MCS) for use in cooperative research projects. The SDLS operates under the mandates of the Antarctic Treaty System, by which all institutions that collect MCS data in Antarctica must submit their MCS data to the SDLS. The SDLS has library branches worldwide at which researchers may view and study the MCS data. MCS data are submitted to the SDLS within 4 years of collection and remain in the library under SDLS guidelines until 8 years after collection. Thereafter, the data go to World Data Centers or equivalents for unrestricted use. The SDLS offers a clearing house, based at Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS) where data are processed when needed and georeferenced, so that the end user can be provided with usable, although basic, post-stack seismic sections. Re-processing of data is beyond the scope of the SDLS, so that if a researcher is interested in reviewing pre-stack data he/she must resort to the data owner. So far 228,000 km of seismic data have been made public in all sectors of the Antarctic region. To augment the concept of physical repositories where data can be accessed by researchers travelling to one of the branches or from where data could be copied to digital media and sent to users, in 2003 it was decided to develop a web interface where data could be searched for and accessed directly. At that moment no previous non-commercial experience was available in this data field, so that the system was designed from scratch. Several technologies were introduced, tested, and after a period of use, reviewed and tuned. Particular attention was devoted to the seismic data viewing facility, which was tailored to the needs of a community with specific practices and legacies. Seismic data are sensitive data that are very important for the E&P industry, so

  3. Penicillium araracuarense sp. nov., Penicillium elleniae sp. nov., Penicillium penarojense sp. nov., Penicillium vanderhammenii sp. nov. and Penicillium wotroi sp. nov., isolated from leaf litter

    DEFF Research Database (Denmark)

    Houbraken, Jos; López-Quintero, Carlos A.; Frisvad, Jens Christian

    2011-01-01

    Several species of the genus Penicillium were isolated during a survey of the mycobiota of leaf litter and soil in Colombian Amazon forest. Five species, Penicillium penarojense sp. nov. (type strain CBS 113178T = IBT 23262T), Penicillium wotroi sp. nov. (type strain CBS 118171T = IBT 23253T......), Penicillium araracuarense sp. nov. (type strain CBS 113149T = IBT 23247T), Penicillium elleniae sp. nov. (type strain CBS 118135T = IBT 23229T) and Penicillium vanderhammenii sp. nov. (type strain CBS 126216T = IBT 23203T) are described here as novel species. Their taxonomic novelty was determined using......, andrastin A, pulvilloric acid, paxillin, paspaline and janthitrem, were commonly produced by these phylogenetically related species. The novel species had a high growth rate on agar media, but could be distinguished from each other by several macro- and microscopical characteristics....

  4. Uji Fitokimia, Kandungan Total Fenol dan Aktivitas Antioksidan Mikroalga Spirulina sp., Chlorella sp., dan Nannochloropsis sp.

    Directory of Open Access Journals (Sweden)

    Diini Fithriani

    2015-12-01

    Full Text Available Penelitian ini bertujuan untuk mengetahui kandungan fitokimia, total fenol, dan aktivitas antioksidan dari mikroalga Spirulina sp., Nannochloropsis sp., dan Chlorella sp. Mikroalga diekstrak dengan ekstraksi tunggal menggunakan etanol. Skrining fitokimia dilakukan secara kualitatif. Analisis total fenol dilakukan secara spektrofotometri dengan metode Folin-Ciocalteu. Analisis antioksidan dilakukan dengan metode 2,2-diphenyl-1-picrylhydrazyl (DPPH dan Ferric Reducing Antioxidant Power (FRAP. Skrining fitokimia menunjukkan keberadaan tanin, flavonoid, steroid, glikosida, dan alkaloid pada ekstrak etanol ketiga jenis mikroalga, sedangkan saponin hanya terdeteksi pada ekstrak etanol Spirulina sp. dan Chlorella sp., adapun triterpenoid tidak terdeteksi pada ekstrak etanol ketiga jenis mikroalga. Hasil penelitian menunjukkan bahwa kandungan total fenol, aktivitas antioksidan (IC50, dan kapasitas antioksidan (FRAP tertinggi diperoleh pada ekstrak etanol Spirulina sp. dengan nilai berturut turut sebesar 0,32 ± 0,025 mg GAE g-1D.W., 518,94 ppm, dan  49,95 ± 2,02 (mmol Fe2+ eq.g-1D.W. Dalam penelitian ini diketahui bahwa kandungan fenol total memiliki korelasi  yang kuat  dengan kapasitas antioksidan metode FRAP (R2= 0,84, dan aktivitas antioksidan metode DPPH (R2= 0,79.

  5. Uji Fitokimia, Kandungan Total Fenol Dan Aktivitas Antioksidan Mikroalga Spirulina Sp., Chlorella Sp., dan Nannochloropsis Sp.

    Directory of Open Access Journals (Sweden)

    Diini Fithriani

    2015-12-01

    Full Text Available Penelitian ini bertujuan untuk mengetahui kandungan fitokimia, total fenol, dan aktivitas antioksidan dari mikroalga Spirulina sp., Nannochloropsis sp., dan Chlorella sp. Mikroalga diekstrak dengan ekstraksi tunggal menggunakan etanol. Skrining fitokimia dilakukan secara kualitatif. Analisis total fenol dilakukan secara spektrofotometri dengan metode Folin-Ciocalteu. Analisis antioksidan dilakukan dengan metode 2,2-diphenyl-1-picrylhydrazyl (DPPH dan Ferric Reducing Antioxidant Power (FRAP. Skrining fitokimia menunjukkan keberadaan tanin, flavonoid, steroid, glikosida, dan alkaloid pada ekstrak etanol ketiga jenis mikroalga, sedangkan saponin hanya terdeteksi pada ekstrak etanol Spirulina sp. dan Chlorella sp., adapun triterpenoid tidak terdeteksi pada ekstrak etanol ketiga jenis mikroalga. Hasil penelitian menunjukkan bahwa kandungan total fenol, aktivitas antioksidan (IC50, dan kapasitas antioksidan (FRAP tertinggi diperoleh pada ekstrak etanol Spirulina sp. dengan nilai berturut turut sebesar 0,32 ± 0,025 mg GAE g-1D.W., 518,94 ppm, dan  49,95 ± 2,02 (mmol Fe2+ eq.g-1D.W. Dalam penelitian ini diketahui bahwa kandungan fenol total memiliki korelasi  yang kuat  dengan kapasitas antioksidan metode FRAP (R2= 0,84, dan aktivitas antioksidan metode DPPH (R2= 0,79.

  6. Intraplate Earthquakes and Deformation within the East Antarctic Craton

    Science.gov (United States)

    Lough, A. C.; Wiens, D.; Nyblade, A.

    2017-12-01

    The apparent lack of tectonic seismicity within Antarctica has long been discussed. Explanations have ranged from a lack of intraplate stress due to the surrounding spreading ridges and low absolute plate velocity (Sykes, 1978), to the weight of ice sheets increasing the vertical normal stress (Johnston, 1987). The 26 station GAMSEIS/AGAP array deployed in East Antarctica from late 2008 to early 2010 provides the first opportunity to study the intraplate seismicity of the Antarctic interior using regional data. Here we report 27 intraplate tectonic earthquakes that occurred during 2009. Depth determination together with their corresponding uncertainty estimates, show that most events originate in the shallow to middle crust, indicating a tectonic and not a cryoseismic origin. The earthquakes are primarily located beneath linear alignments of basins adjacent to the Gamburtsev Subglacial Mountains (GSM) that have been denoted as the East Antarctic rift system (Ferraccioli et al, 2011). The geophysical properties of the `rift' system contrast sharply with those of the GSM and Vostok Subglacial Highlands on either side. Crustal thickness, seismic velocity, and gravity anomalies all indicate large lateral variation in lithospheric properties. We propose the events outline an ancient continental rift, a terrain boundary feature, or a combination of the two where rifting exploited pre-existing weakness. It is natural to draw parallels between East Antarctica and the St. Lawrence depression where rifting and a collisional suture focus intraplate earthquakes within a craton (Schulte and Mooney, 2005). We quantify the East Antarctic seismicity by developing a frequency-magnitude relation, constraining the lower magnitudes with the 2009 results and the larger magnitudes with 1982-2012 teleseismic seismicity. East Antarctica and the Canadian Shield show statistically indistinguishable b-values (near 1) and seismicity rates as expressed as the number of events with mb > 4 per

  7. Partial Characterization of α-Galactosidic Activity from the Antarctic Bacterial Isolate, . LX-20 as a Potential Feed Enzyme Source

    Directory of Open Access Journals (Sweden)

    Inkyung Park

    2012-06-01

    Full Text Available An Antarctic bacterial isolate displaying extracellular α-galactosidic activity was named Paenibacillus sp. LX-20 based on 16S rRNA gene sequence analysis. Optimal activity for the LX-20 α-galactosidase occurred at pH 6.0–6.5 and 45°C. The enzyme immobilized on the smart polymer Eudragit L-100 retained 70% of its original activity after incubation for 30 min at 50°C, while the free enzyme retained 58% of activity. The enzyme had relatively high specificity for α-D-galactosides such as p-nitrophenyl-α-galactopyranoside, melibiose, raffinose and stachyose, and was resistant to some proteases such as trypsin, pancreatin and pronase. Enzyme activity was almost completely inhibited by Ag+, Hg2+, Cu2+, and sodium dodecyl sulfate, but activity was not affected by β-mercaptoethanol or EDTA. LX-20 α-galactosidase may be potentially useful as an additive for soybean processing in the feed industry.

  8. Oxidative stress responses in the marine antarctic diatom Chaetoceros brevis (Bacillariophyceae) during photoacclimation

    NARCIS (Netherlands)

    Janknegt, Paul J.; van de Poll, Willem H.; Visser, Ronald J. W.; Rijstenbil, Jan W.; Buma, Anita G. J.

    The enzyme superoxide dismutase (SOD) holds a key position in the microalgal antioxidant network. The present research focused on oxidative stress responses in the Antarctic diatom Chaetoceros brevis F. Schutt during transition to excess (including ultraviolet radiation [UVR]) and limiting

  9. Water characteristics and transport of the Antarctic circumpolar current in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; Mathew, B.

    Geostrophic velocities are computed across meridians 37 degrees E and 105 degrees E using hydrographic data. The estimated mass transport is represented on a temperature - salinity diagram. The characteristics of the water within the Antarctic...

  10. Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula - 1988-1989, SDLS CD-ROM vol 25

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1988-89 in the Antarctic Peninsula, Antarctica, by the Japan National Oil...

  11. Temperature Profile of the West Antarctic Ice Sheet Divide Deep Borehole, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports depth versus temperatures in the fluid-filled portion of the West Antarctic Ice Sheet Divide (WAIS–D) deep borehole (70 to 3328 meters depth)....

  12. 77 FR 50720 - Notice of Permit Modification Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-08-22

    ... 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has..., experience and physiology on individual foraging efficiency, breeding success and survival, and develop a...

  13. Polybrominated diphenyl ether contamination levels in fish from the Antarctic and the Mediterranean Sea

    NARCIS (Netherlands)

    Borghesi, N.; Corsolini, S.; Leonards, P.E.G.; Brandsma, S.H.; de Boer, J.

    2009-01-01

    Polybrominated diphenyl ethers (PBDEs) concentrations and congener profiles were evaluated in four species of Antarctic fish (Chionodraco hamatus, Chaempsocephalus gunnari, Gymnoscopelus nicholsi, Trematomus eulepidotes) and in one Mediterranean species (Tuna, Thunnus thynnus). The GC/MS-ECNI

  14. Developing a 1:3,000,000 Arctic and Antarctic Regions Shoreline Using the WVS Plus

    National Research Council Canada - National Science Library

    Doody, Martin

    1998-01-01

    .... The Naval Research Laboratory Geographic Information Systems (GIS) Lab has been tasked to assist in the EWG project by creating a shoreline for the Arctic and Antarctic Areas of Interest (AOI) defined by NIC...

  15. 77 FR 60477 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-10-03

    ... 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has... study of temporal and spatial scales of various types of disturbances in and around McMurdo Station. The...

  16. Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula - 1985, SDLS CD-ROM vol 16

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1985 field season along the north side of the Antarctic-Peninsula by the British...

  17. NASA SCP Arctic and Antarctic Ice Extent from QuikSCAT, 1999-2009, Version 2

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides sea ice extent for the Arctic (60-90 degrees North) and Antarctic (52-90 degrees South) in Scatterometer Image Reconstruction (SIR) binary...

  18. MEaSUREs Annual Antarctic Ice Velocity Maps 2005-2017 V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, provides 12 annual maps of Antarctic ice...

  19. MEaSUREs Antarctic Boundaries for IPY 2007-2009 from Satellite Radar V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, and provides maps of Antarctic ice shelves,...

  20. MEaSUREs Annual Antarctic Ice Velocity Maps 2005-2017, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, provides 12 annual maps of Antarctic ice...

  1. MEaSUREs Antarctic Boundaries for IPY 2007-2009 from Satellite Radar, Version 2

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, and provides maps of Antarctic ice shelves,...

  2. MEaSUREs Annual Antarctic Ice Velocity Maps 2005-2016, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, provides 11 annual maps of Antarctic ice...

  3. Atmospheric Mixing Ratios of Hydroperoxides above the West Antarctic Ice Sheet, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains atmospheric mixing ratios of hydrogen peroxide and methylhydroperoxide at 21 sites on the West Antarctic Ice Sheet (WAIS) were obtained from...

  4. Multiple Isotope Analysis of Sulfate in the West Antarctic Ice Sheet Divide Ice Core, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains measurements of multiple sulfur and oxygen isotopes from sulfates, from an ice core drilled at the West Antarctic Ice Sheet (WAIS) Divide site...

  5. Age, growth and distribution of the Antarctic fish Chaenocephalus aceratus based on otoliths

    Directory of Open Access Journals (Sweden)

    Ryszard Jacek Traczyk

    2015-10-01

    Żabrowski, M. 2000. The osteology and ossification variability of the skull of antarctic white-blooded fish Chaenodraco wilsoni Regan, 1914 (Channichthyidae, Notothenioidei. W-wa : Acta Icht. Piscat. 30 (2: 111-126.

  6. New and interesting small-celled naviculoid diatoms (Bacillariophyta) from the Maritime Antarctic Region

    Czech Academy of Sciences Publication Activity Database

    Van de Vijver, B.; Kopalová, Kateřina; Zidarova, R.; Cox, E. J.

    2013-01-01

    Roč. 97, 1-2 (2013), s. 189-208 ISSN 0029-5035 Institutional support: RVO:67985939 Keywords : Bacillariophyta * Diatoms * Maritime Antarctic Region Subject RIV: EF - Botanics Impact factor: 0.989, year: 2013

  7. Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula 1987-88, SDLS CD-ROM vol 24

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1987-88 in the Antarctic Peninsula, Antarctica, by the Japan National Oil...

  8. ICESat-Derived Grounding Zone for Antarctic Ice Shelves, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes estimates of the location of the grounding zone of Antarctic ice shelves based on laser altimeter data acquired during the Ice, Cloud, and...

  9. 77 FR 23766 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-04-20

    ... 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has... importance within the Ross Sea region. The collected imagery will used for further scientific analysis...

  10. NASA SCP Arctic and Antarctic Ice Extent from QuikSCAT, 1999-2004

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides sea ice extent for the Arctic (60-90 degrees North) and Antarctic (52-90 degrees South) in Scatterometer Image Reconstruction (SIR) binary...

  11. 78 FR 51213 - Notice of Permits Issued Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-08-20

    ... 2401 et seq.), and Article 7 of the Protocol on Environmental Protection to the Antarctic Treaty done... September 4, 2013. Nadene G. Kennedy, Polar Coordination Specialist, Division of Polar Programs. [FR Doc...

  12. TRACKING DISPERSAL ROUTES - PHYLOGEOGRAPHY OF THE ARCTIC ANTARCTIC DISJUNCT SEAWEED ACROSIPHONIA-ARCTA (CHLOROPHYTA)

    NARCIS (Netherlands)

    VANOPPEN, MJH; DIEKMANN, OE; WIENCKE, C; STAM, WT; OLSEN, JL

    Phylogenetic relationships in the Arctic-Antarctic disjunct seaweed species Acrosiphonia arcta (Dillwyn) J. G. Agardh (Acrosiphoniales, Chlorophyta) were examined using restriction fragment-length polymorphism analysis of the fast-evolving nuclear ribosomal intergenic spacer (IGS) region and random

  13. Mean Antarctic Circumpolar Current transport measured in Drake Passage

    Science.gov (United States)

    Donohue, K. A.; Tracey, K. L.; Watts, D. R.; Chidichimo, M. P.; Chereskin, T. K.

    2016-11-01

    The Antarctic Circumpolar Current is an important component of the global climate system connecting the major ocean basins as it flows eastward around Antarctica, yet due to the paucity of data, it remains unclear how much water is transported by the current. Between 2007 and 2011 flow through Drake Passage was continuously monitored with a line of moored instrumentation with unprecedented horizontal and temporal resolution. Annual mean near-bottom currents are remarkably stable from year to year. The mean depth-independent or barotropic transport, determined from the near-bottom current meter records, was 45.6 sverdrup (Sv) with an uncertainty of 8.9 Sv. Summing the mean barotropic transport with the mean baroclinic transport relative to zero at the seafloor of 127.7 Sv gives a total transport through Drake Passage of 173.3 Sv. This new measurement is 30% larger than the canonical value often used as the benchmark for global circulation and climate models.

  14. Antarctic Wave Dynamics Mystery Discovered by Lidar, Radar and Imager

    Directory of Open Access Journals (Sweden)

    Chen Cao

    2016-01-01

    Full Text Available Since the start of the McMurdo Fe lidar campaign, largeamplitude (~±30 K, long-period (4 to 9 h waves with upward energy propagating signatures are frequently observed in the MLT temperatures. Despite its frequent appearance, such type of wave was neither widely observed nor well understood in the past. At McMurdo (77.8°S, 166.7°E, the simultaneous observations of such waves using lidar, radar and airglow imager can provide 3-D intrinsic wave-propagation properties, which are greatly needed for understanding their sources and potential impacts. This study presents the first coincident observation of these 4–9 h waves by lidar, radar and airglow imager in the Antarctic mesopause region.

  15. Curation and Allocation of the New Antarctic Nakhlite, MIL03346

    Science.gov (United States)

    McBride, K. M.; Righter, K.; Satterwhite, C. E.; Schwarz, C.; Robinson, P.

    2005-01-01

    In January 2004, the ANSMET reconnaissance field team (Fig. 1) working in the Miller Range of the Transantarctic Mountains discovered a 715 g achondrite that was instantly recognized as unique. Named MIL03346, initial processing (NASA Johnson Space Center or JSC) and classification (Smithsonian Institution or SI) revealed this achondrite to be a nakhlite (Fig. 2). MIL03346 is the seventh nakhlite recognized in world collections [2], the third nakhlite returned from Antartica, and the first nakhlite in the US Antarctic collection (Table 1). The following is a summary of the steps taken in the processing and allocating of MIL 03346 and some comparisons to some other lunar and martian meteorites processed and allocated at JSC.

  16. Atmospheric ozone and colors of the Antarctic twilight sky.

    Science.gov (United States)

    Lee, Raymond L; Meyer, Wolfgang; Hoeppe, Götz

    2011-10-01

    Zenith skylight is often distinctly blue during clear civil twilights, and much of this color is due to preferential absorption at longer wavelengths by ozone's Chappuis bands. Because stratospheric ozone is greatly depleted in the austral spring, such decreases could plausibly make Antarctic twilight colors less blue then, including at the zenith. So for several months in 2005, we took digital images of twilight zenith and antisolar skies at Antarctica's Georg von Neumayer Station. Our colorimetric analysis of these images shows only weak correlations between ozone concentration and twilight colors. We also used a spectroradiometer at a midlatitude site to measure zenith twilight spectra and colors. At both locations, spectral extinction by aerosols seems as important as ozone absorption in explaining colors seen throughout the twilight sky.

  17. Quality changes of Antarctic krill powder during long term storage

    DEFF Research Database (Denmark)

    Nielsen, Nina Skall; Lu, Henna Fung Sieng; Bruheim, Inge

    2017-01-01

    of packaging in vacuum was observed. The stability was assessed by changes in concentrations of lipid classes, antioxidants, pyrroles and lipid, and Strecker-derived volatiles. Some degradation occurred during storage at room temperature. Thus, a minor increase in volatiles, an increase in free fatty acids...... and a concomitant decrease in antioxidants, tocopherol, and astaxanthin was observed. In addition, there was a minor decrease in phospholipids and n-3 fatty acids; however, storage at vacuum improved the oxidative stability of krill powder. Practical applications: For the use of krill powder in human nutrition......, it is important, that the quality and stability is sufficiently high to retain the nutritional value during storage. This study contributes with information about the stability during storage up to 12 months at room temperature and the effect of packaging the powder in vacuum. Antarctic krill (Euphausia superba...

  18. Emergence of healing in the Antarctic ozone layer.

    Science.gov (United States)

    Solomon, Susan; Ivy, Diane J; Kinnison, Doug; Mills, Michael J; Neely, Ryan R; Schmidt, Anja

    2016-07-15

    Industrial chlorofluorocarbons that cause ozone depletion have been phased out under the Montreal Protocol. A chemically driven increase in polar ozone (or "healing") is expected in response to this historic agreement. Observations and model calculations together indicate that healing of the Antarctic ozone layer has now begun to occur during the month of September. Fingerprints of September healing since 2000 include (i) increases in ozone column amounts, (ii) changes in the vertical profile of ozone concentration, and (iii) decreases in the areal extent of the ozone hole. Along with chemistry, dynamical and temperature changes have contributed to the healing but could represent feedbacks to chemistry. Volcanic eruptions have episodically interfered with healing, particularly during 2015, when a record October ozone hole occurred after the Calbuco eruption. Copyright © 2016, American Association for the Advancement of Science.

  19. SPREADING OF ANTARCTIC BOTTOM WATER IN THE ATLANTIC OCEAN

    Directory of Open Access Journals (Sweden)

    Eugene Morozov

    2012-01-01

    Full Text Available This paper describes the transport of bottom water from its source region in the Weddell Sea through the abyssal channels of the Atlantic Ocean. The research brings together the recent observations and historical data. A strong flow of Antarctic Bottom Water through the Vema Channel is analyzed. The mean speed of the flow is 30 cm/s. A temperature increase was found in the deep Vema Channel, which has been observed for 30 years already. The flow of bottom water in the northern part of the Brazil Basin splits. Part of the water flows through the Romanche and Chain fracture zones. The other part flows to the North American Basin. Part of the latter flow propagates through the Vema Fracture Zone into the Northeast Atlantic. The properties of bottom water in the Kane Gap and Discovery Gap are also analyzed.

  20. Emergence of healing in the Antarctic ozone layer

    Science.gov (United States)

    Solomon, Susan; Ivy, Diane J.; Kinnison, Doug; Mills, Michael J.; Neely, Ryan R.; Schmidt, Anja

    2016-07-01

    Industrial chlorofluorocarbons that cause ozone depletion have been phased out under the Montreal Protocol. A chemically driven increase in polar ozone (or “healing”) is expected in response to this historic agreement. Observations and model calculations together indicate that healing of the Antarctic ozone layer has now begun to occur during the month of September. Fingerprints of September healing since 2000 include (i) increases in ozone column amounts, (ii) changes in the vertical profile of ozone concentration, and (iii) decreases in the areal extent of the ozone hole. Along with chemistry, dynamical and temperature changes have contributed to the healing but could represent feedbacks to chemistry. Volcanic eruptions have episodically interfered with healing, particularly during 2015, when a record October ozone hole occurred after the Calbuco eruption.

  1. Migration of Antarctic minke whales to the Arctic.

    Directory of Open Access Journals (Sweden)

    Kevin A Glover

    2010-12-01

    Full Text Available The Antarctic minke whale (Balaenoptera bonaerensis, and the common minke whale found in the North Atlantic (Balaenoptera acutorostrata acutorostrata, undertake synchronized seasonal migrations to feeding areas at their respective poles during spring, and to the tropics in the autumn where they overwinter. Differences in the timing of seasons between hemispheres prevent these species from mixing. Here, based upon analysis of mitochondrial and microsatellite DNA profiles, we report the observation of a single B. bonaerensis in 1996, and a hybrid with maternal contribution from B. bonaerensis in 2007, in the Arctic Northeast Atlantic. Paternal contribution was not conclusively resolved. This is the first documentation of B. bonaerensis north of the tropics, and, the first documentation of hybridization between minke whale species.

  2. Life style and biochemical adaptation in Antarctic fishes

    Science.gov (United States)

    di Prisco, Guido

    2000-12-01

    Respiration and metabolism are under investigation in Antarctic fish, in an effort to understand the interplay between ecology and biochemical and physiological processes. Fish of the dominant suborder Notothenioidei are red-blooded, except Channichthyidae (the most phyletically derived family), whose genomes retain transcriptionally inactive DNA sequences closely related to the α-globin gene of red-blooded notothenioids and have lost the β-globin locus. Our structure/function studies on 38 of the 80 red-blooded species are aimed at correlating sequence, multiplicity and oxygen binding with ecological constraints and at obtaining phylogenetic information on evolution. For comparative purposes, this work has been extended to non-Antarctic notothenioids. All sluggish bottom dwellers have a single major hemoglobin (Hb) and often a minor, functionally similar one. Three species of the family Nototheniidae have different life styles. They have uniquely specialised oxygen-transport systems, adjusted to the mode of life of each species. Artedidraconidae have a single Hb, lacking oxygen-binding cooperativity, similar to the ancestral hemoproteins of primitive organisms. The amino acid sequences are currently used in the molecular modelling approach. The study of several enzymes with key roles in metabolism (e.g. glucose-6-phosphate dehydrogenase, L-glutamate dehydrogenase, phosphorylase b, carbonic anhydrase) indicate that some aspects of the molecular structure (e.g. molecular mass, number of subunits, amino acid sequence, temperature of irreversible heat inactivation) have been conserved during development of cold adaptation. However, high catalytic efficiency, possibly due to subtle molecular changes, is observed at low temperature.

  3. Development of a multi-parameter system for Antarctic researching

    Science.gov (United States)

    Garcia, Alicia; Peci, Luis Miguel; Berrocoso, Manuel; Fernandez-Ros, Alberto; Marrero, Jose Manuel; Ortiz, Ramon

    2014-05-01

    This work describes the development of a multi-parameter system for antarctic researching. The system permits the remote access and the connection of several modules in a network. An embedded ARM processor has been used, allowing a great flexibility in hardware configuration.The advantage of the system presented in this work is that it allows the rapid development of a monitoring network that uses the latest technologies of embedded systems. These embedded systems offer the possibility of developing the software necessary for managing the sensors and instruments available. Data can be transmitted in near real time or on demand to a Data Reception Center (DRC). The local storage allows retrieving data when the transmission fails and uses only short transmission periods rather than continuous transmission. The price of both hardware and software is very low. The use of a complete Linux solution (Debian) as Operating System permits a quick, easy application development to control sensors and communications. This provides all the capabilities required and great stability with relatively low energy consumption. The cost of the components and applications development is low since they are widely used in different fields. Sensors and commercial modules have been combined with other self-developed modules. The Modular System described has been deployed at Deception Island (Antarctica), within the Spanish Antarctic Program, and has proved successful for monitoring and researching the geodinamical activity, with proven reliability and efficient operation under extreme conditions. Deception Islan is an active volcano with some geothermal areas, this fact has allowed to develop a power system using Peltier cells. In another context, i.e., the recent volcanic activity on El Hierro Island (Canary Islands) in 2011, this technology has been used for the seismic equipment and GPS systems deployed, thus showing its efficiency in the monitoring of a volcanic crisis.

  4. Assessing environmental conditions of Antarctic footpaths to support management decisions.

    Science.gov (United States)

    Tejedo, Pablo; Benayas, Javier; Cajiao, Daniela; Albertos, Belén; Lara, Francisco; Pertierra, Luis R; Andrés-Abellán, Manuela; Wic, Consuelo; Luciáñez, Maria José; Enríquez, Natalia; Justel, Ana; Reck, Günther K

    2016-07-15

    Thousands of tourists visit certain Antarctic sites each year, generating a wide variety of environmental impacts. Scientific knowledge of human activities and their impacts can help in the effective design of management measures and impact mitigation. We present a case study from Barrientos Island in which a management measure was originally put in place with the goal of minimizing environmental impacts but resulted in new undesired impacts. Two alternative footpaths used by tourist groups were compared. Both affected extensive moss carpets that cover the middle part of the island and that are very vulnerable to trampling. The first path has been used by tourists and scientists since over a decade and is a marked route that is clearly visible. The second one was created more recently. Several physical and biological indicators were measured in order to assess the environmental conditions for both paths. Some physical variables related to human impact were lower for the first path (e.g. soil penetration resistance and secondary treads), while other biochemical and microbiological variables were higher for the second path (e.g. β-glucosidase and phosphatase activities, soil respiration). Moss communities located along the new path were also more diverse and sensitive to trampling. Soil biota (Collembola) was also more abundant and richer. These data indicate that the decision to adopt the second path did not lead to the reduction of environmental impacts as this path runs over a more vulnerable area with more outstanding biological features (e.g. microbiota activity, flora and soil fauna diversity). In addition, the adoption of a new route effectively doubles the human footprint on the island. We propose using only the original path that is less vulnerable to the impacts of trampling. Finally from this process, we identify several key issues that may be taken into account when carrying out impact assessment and environmental management decision-making in the

  5. Microbial mineralization processes in Antarctic soils and on plant material

    International Nuclear Information System (INIS)

    Boelter, M.

    1991-01-01

    Soil samples and different plant material from the maritime and continental Antarctic were analyzed for their actual and potential respiration by different methods: total CO 2 -evolution, biological oxygen demand and use of 14C-labeled glucose which may serve as a model for dissolved organic carbohydrates. Since these methods are argued to indicate the mineralization of different fractions of the total organic material by different actual populations, a comparison between the data from these techniques is carried out with regard to their contributions of the total organic matter debris in these environments. The part of respired material calculated from 14C-studies may contribute to nearly 90% of the metabolized material. Results show that the individual fractions differ significantly with respect to the parent material. There are several aspects which have to be taken into account when looking at these data: the original content of water; the contents of dissolved and particulate carbohydrates; and, other edaphic factors. Of special interest is the overall respiration of plant material (mainly lichens) which is strongly influenced by the bacterial respiration of dissolved carbohydrates, probably by ongrowing organisms due to their efficiency in using dissolved organic matter. In terms of respiratory activity, the (bacterial) respiration of glucose may contribute to more than 50% of the total CO 2 -evolution. This influences considerably the modeling of overall respiration of plant material in those environments where close interactions between different parts of the system are very important for their life strategy. Further, the bacterial part may be an overlooked part of metabolic rates in Antarctic lichens

  6. Controls on turbulent mixing on the West Antarctic Peninsula shelf

    Science.gov (United States)

    Brearley, J. Alexander; Meredith, Michael P.; Naveira Garabato, Alberto C.; Venables, Hugh J.; Inall, Mark E.

    2017-05-01

    The ocean-to-atmosphere heat budget of the West Antarctic Peninsula is controlled in part by the upward flux of heat from the warm Circumpolar Deep Water (CDW) layer that resides below 200 m to the Antarctic Surface Water (AASW), a water mass which varies strongly on a seasonal basis. Upwelling and mixing of CDW influence the formation of sea ice in the region and affect biological productivity and functioning of the ecosystem through their delivery of nutrients. In this study, 2.5-year time series of both Acoustic Doppler Current Profiler (ADCP) and conductivity-temperature-depth (CTD) data are used to quantify both the diapycnal diffusivity κ and the vertical heat flux Q at the interface between CDW and AASW. Over the period of the study, a mean upward heat flux of 1 W m-2 is estimated, with the largest heat fluxes occurring shortly after the loss of winter fast ice when the water column is first exposed to wind stress without being strongly stratified by salinity. Differences in mixing mechanisms between winter and summer seasons are investigated. Whilst tidally-driven mixing at the study site occurs year-round, but is likely to be relatively weak, a strong increase in counterclockwise-polarized near-inertial energy (and shear) is observed during the fast-ice-free season, suggesting that the direct impact of storms on the ocean surface is responsible for much of the observed mixing at the site. Given the rapid reduction in sea-ice duration in this region in the last 30 years, a shift towards an increasingly wind-dominated mixing regime may be taking place.

  7. Effects of iron and light stress on the biochemical composition of Antarctic Phaeocystis sp. (Prymnesiophyceae). I. Intracellular DMSP concentrations

    NARCIS (Netherlands)

    Stefels, J; van Leeuwe, MA

    Iron is essential for phytoplankton growth, as it is involved in many metabolic processes. It controls photosynthesis as well as many enzymatic processes. As such, iron affects the cell's energy supply and contributes to the assimilation of carbon and nitrogen. To determine whether iron limitation

  8. Environmental effects of the US Antarctic Program`s use of balloons in Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    McCold, L.N.; Eddlemon, G.K.; Blasing, T.J.

    1995-06-01

    The USAP uses balloons in Antarctica to conduct scientific research, to facilitate safe air transport, and to provide data for global weather predictions. However, there is the possibility that balloons or their payloads may adversely affect Antarctic fauna or flora. The purpose of this study is to provide background information upon which the USAP may draw when complying with its responsibilities under the National Environmental Policy Act of 1969, the Antarctic Treaty, and the Madrid Protocol.

  9. Differential pulse anodic stripping voltametry for ultratrace determination of cadmium and lead in Antarctic snow

    International Nuclear Information System (INIS)

    Scarponi, G.; Barbante, C.; Cescon, P.

    1994-01-01

    Differential pulse anodic stripping voltametry has sufficient sensitivity to be used for direct determination of heavy metals in Antarctic snow, thus avoiding long and contamination-prone enrichment procedures. A result of particular concern to global change studies can be drawn from these preliminary data: lead concentration in Antarctic snow decreased rapidly during the 1980s from about 10-15 pg/g to 2-4 pg/g in 1991. (authors). 16 refs., 3 figs., 1 tab

  10. Shifts in soil microorganisms in response to warming are consistent across a range of Antarctic environments

    OpenAIRE

    Yergeau, Etienne; Bokhorst, Stef; Kang, Sanghoon; Zhou, Jizhong; Greer, Charles W; Aerts, Rien; Kowalchuk, George A

    2011-01-01

    Because of severe abiotic limitations, Antarctic soils represent simplified systems, where microorganisms are the principal drivers of nutrient cycling. This relative simplicity makes these ecosystems particularly vulnerable to perturbations, like global warming, and the Antarctic Peninsula is among the most rapidly warming regions on the planet. However, the consequences of the ongoing warming of Antarctica on microorganisms and the processes they mediate are unknown. Here, using 16S rRNA ge...

  11. Report on field research of the Spanish Antarctic Campaign 2014/15: a cooperative international research project with the 56th Japanese Antarctic Research Expedition

    Directory of Open Access Journals (Sweden)

    Sakae Kudoh

    2015-07-01

    Full Text Available A study on the limnological and ecological characteristics of maritime Antarctic lakes on Byers Peninsula, Livingstone Island, South Shetland Islands, West Antarctica, was conducted by the Spanish Antarctic Research Campaign during the 2014/15 season, in cooperation with the research program of the 56th Japanese Antarctic Research Expedition. Limnological surveys of three hillside lakes and three lagoons near beaches were conducted under conditions of heavy snow cover. Soils and biological samples in the catchment areas of the lakes and lagoons were also collected and analyzed. The hillside lakes were covered by thick ice and snow, which maintained winter water conditions in the lakes, such as irreversible stratification, oxygen depletion of bottom water, very weak underwater light conditions, etc., even in mid-January, although swimming zooplankton were abundant. Water samples were also collected in coastal lagoons and streams, an environment in which birds and marine mammals transport materials through the aquatic system.

  12. Treatment and prevention of infection following bites of the Antarctic fur seal (Arctocephalus gazella

    Directory of Open Access Journals (Sweden)

    Kouliev T

    2015-04-01

    Full Text Available Timur Kouliev,1 Victoria Cui2 1Beijing United Family Hospital, Beijing, People's Republic of China; 2Department of Biological Sciences, Columbia University, New York, NY, USA Abstract: In recent decades, an increasing number of people have traveled to sub-Antarctic and Antarctic regions each year for research, tourism, and resource exploitation. Hunting of Antarctic fur seals (Arctocephalus gazella almost pushed the species to extinction in the early 1900s, but populations have since shown rapid and substantial recovery. The species' range has re-expanded to include several islands south of the Antarctic Convergence, most notably South Georgia, and now overlaps with many popular Antarctic travel destinations. Both male and female fur seals can become extremely aggressive when provoked, and their bites, if not properly treated, pose a significant risk of infection by microorganisms not usually encountered in cases of animal bites. In this report, we present the case of a patient treated for a fur seal bite during an Antarctic expedition cruise, review the literature concerning seal bites, and suggest the use of antibiotic prophylaxis to prevent complications. Keywords: zoonotic, polar tourism, prophylaxis, seal finger, expedition medicine

  13. OXYGEN CONSUMPTION AND AMMONIA EXCRETION OF THE ANTARCTIC AMPHIPOD Bovallia gigantea PFEFFER, 1888, AT DIFFERENT TEMPERATURES AND SALINITIES

    OpenAIRE

    Gomes, Vicente; Passos, Maria José de Arruda Campos Rocha; Rocha, Arthur José da Silva; Santos, Thais da Cruz Alves dos; Hasue, Fabio Matsu; Ngan, Phan Van

    2014-01-01

    The energy budget of Antarctic stenothermic and/or stenohaline ectotherms is modulated by variations of temperature and salinity. The joint effects of these latter on polar organisms have been but little studied. Data on this subject are of great importance for an understanding of the energy demand of Antarctic animals such as amphipods, especially when considering their ecological importance and the possible impacts of global changes. Experiments were carried out at the Brazilian Antarctic S...

  14. New tentacled leech Ceratobdella quadricornuta n. g., n. sp. (Hirudinida: Piscicolidae) parasitic on the starry skate Raja georgiana Norman from the Scotia Sea, Antarctica.

    Science.gov (United States)

    Utevsky, Andrei; Gordeev, Ilya

    2015-07-01

    A new fish leech Ceratobdella quadricornuta n. g., n. sp. (Hirudinida: Piscicolidae), a parasite of the Antarctic skate Raja georgiana Norman (Rajiformes: Rajidae) collected between the Falkland Islands and South Georgia Island in the Scotia Sea, is described and compared with related genera. Ceratobdella quadricornuta is characterised by an uncommon appearance of its anterior sucker bearing four well-developed tentacles and a unique combination of features of the reproductive and digestive systems: crop and intestine equally developed, posterior crop caeca separated; accessory glands, conductive tissue and external copulatory area lacking; common part of ejaculatory ducts (common atrium) voluminous and muscular, male copulatory bursa short, small ovisacs opening into female copulatory bursa (vagina).

  15. Lactobacillus apinorum sp. nov., Lactobacillus mellifer sp. nov., Lactobacillus mellis sp. nov., Lactobacillus melliventris sp. nov., Lactobacillus kimbladii sp. nov., Lactobacillus helsingborgensis sp. nov. and Lactobacillus kullabergensis sp. nov., isolated from the honey stomach of the honeybee Apis mellifera

    Science.gov (United States)

    Alsterfjord, Magnus; Nilson, Bo; Butler, Èile; Vásquez, Alejandra

    2014-01-01

    We previously discovered a symbiotic lactic acid bacterial (LAB) microbiota in the honey stomach of the honeybee Apis mellifera. The microbiota was composed of several phylotypes of Bifidobacterium and Lactobacillus. 16S rRNA gene sequence analyses and phenotypic and genetic characteristics revealed that the phylotypes isolated represent seven novel species. One grouped with Lactobacillus kunkeei and the others belong to the Lactobacillus buchneri and Lactobacillus delbrueckiisubgroups of Lactobacillus. We propose the names Lactobacillus apinorum sp. nov., Lactobacillus mellifer sp. nov., Lactobacillus mellis sp. nov., Lactobacillus melliventris sp. nov., Lactobacillus kimbladii sp. nov., Lactobacillus helsingborgensis sp. nov. and Lactobacillus kullabergensis sp. nov. for these novel species, with the respective type strains being Fhon13NT ( = DSM 26257T = CCUG 63287T), Bin4NT ( = DSM 26254T = CCUG 63291T), Hon2NT ( = DSM 26255T = CCUG 63289T), Hma8NT ( = DSM 26256T = CCUG 63629T), Hma2NT ( = DSM 26263T = CCUG 63633T), Bma5NT ( = DSM 26265T = CCUG 63301T) and Biut2NT ( = DSM 26262T = CCUG 63631T). PMID:24944337

  16. LIFE experiment: isolation of cryptoendolithic organisms from Antarctic colonized sandstone exposed to space and simulated Mars conditions on the international space station.

    Science.gov (United States)

    Scalzi, Giuliano; Selbmann, Laura; Zucconi, Laura; Rabbow, Elke; Horneck, Gerda; Albertano, Patrizia; Onofri, Silvano

    2012-06-01

    Desiccated Antarctic rocks colonized by cryptoendolithic communities were exposed on the International Space Station (ISS) to space and simulated Mars conditions (LiFE-Lichens and Fungi Experiment). After 1.5 years in space samples were retrieved, rehydrated and spread on different culture media. Colonies of a green alga and a pink-coloured fungus developed on Malt-Agar medium; they were isolated from a sample exposed to simulated Mars conditions beneath a 0.1 % T Suprasil neutral density filter and from a sample exposed to space vacuum without solar radiation exposure, respectively. None of the other flight samples showed any growth after incubation. The two organisms able to grow were identified at genus level by Small SubUnit (SSU) and Internal Transcribed Spacer (ITS) rDNA sequencing as Stichococcus sp. (green alga) and Acarospora sp. (lichenized fungal genus) respectively. The data in the present study provide experimental information on the possibility of eukaryotic life transfer from one planet to another by means of rocks and of survival in Mars environment.

  17. 75 FR 22433 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-04-28

    ...-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has developed..., experience and physiology on individual foraging efficiency and breeding performance, and develop a...

  18. The last ice-sheet advance and retreat across the Antarctic continental shelf: Synchrony or diachrony?

    Science.gov (United States)

    Hillenbrand, C.; Livingstone, S. J.; O'Cofaigh, C.; Stokes, C. R.; Vieli, A.; Jamieson, S.; Smith, J.; Kuhn, G.; Melles, M.; Graham, A. G.; Larter, R. D.

    2012-12-01

    Over the last few decades, numerous studies from various sectors of the Antarctic continental shelf have reconstructed the spatial extent of grounded ice-sheet advance during the last glacial period and the timing of its retreat. Most reconstructions were based on the bathymetric mapping of subglacial bedforms on the seabed and the palaeoenvironmental interpretation and dating of sub-seafloor sediments in cores. In addition, surface exposure age dating on rocks from the hinterland using cosmogenic isotopes and ice-sheet models were used to constrain the last ice-sheet advance and retreat. Different regional reconstructions provided consistent results for several study areas. In contrast, recent circum-Antarctic reviews that compiled the spatial and temporal information about maximum ice-sheet advance and retreat from these regional studies came to conflicting conclusions regarding i) the maximum extent of grounded ice, and ii) the synchronous/diachronous behaviour of the northern and southern hemispheric ice sheets and the individual drainage sectors within the Antarctic Ice Sheet, respectively. Resolving these conflicts is essential for identifying the main drivers of Antarctic ice-sheet retreat, evaluating the contribution of Antarctic ice-sheet melting to global sea-level rise over the last ~20 ka, understanding the dynamics of individual drainage sectors within the Antarctic Ice Sheet, and locating possible glacial refuges for benthic organisms on the Antarctic shelf. Here we will present examples of circum-Antarctic reconstructions and discuss possible reasons for conflicting conclusions. In some cases, apparent discrepancies can simply be explained by the ambiguity of terms such as "Last Glacial Maximum", which can refer either to a particular time slice (e.g. 23-19 ka BP) or to the time when grounded ice reached its last maximum extent in a particular sector of the Antarctic continental shelf, and "deglaciation", which can refer either to the time of

  19. Ecdysteroids from a Zoanthus sp.

    Science.gov (United States)

    Suksamrarn, Apichart; Jankam, Aroon; Tarnchompoo, Bongkoch; Putchakarn, Sumaitt

    2002-08-01

    A new ecdysteroid, zoanthusterone, has been isolated from a marine zoanthid, Zoanthus sp. Ten known ecdysteroids, ponasterone A, 20-hydroxyecdysone 2-acetate, viticosterone E, integristerone A 25-acetate, 2-deoxy-20-hydroxyecdysone, ecdysone, ajugasterone C, dacryhainansterone, inokosterone, and 20-hydroxyecdysone, have also been isolated. This is the first report of ecdysteroids in a Zoanthus species.

  20. Sporulation of Cyclospora sp. oocysts.

    OpenAIRE

    Smith, H V; Paton, C A; Mitambo, M M; Girdwood, R W

    1997-01-01

    Cyclospora sp. oocysts sporulated maximally at 22 and 30 degrees C for 14 days retarded sporulation. Up to 12% of human- and baboon-derived oocysts previously stored at 4 degrees C for 1 to 2 months sporulated when stored for 6 to 7 days at 30 degrees C.

  1. Geodetic antenna calibration test in the Antarctic environment

    Science.gov (United States)

    Grejner-Brzezinska, A.; Vazquez, E.; Hothem, L.

    2006-01-01

    TransAntarctic Mountain DEFormation (TAMDEF) Monitoring Network is the NSF-sponsored OSU and USGS project, aimed at measuring crustal motion in the Transantarctic Mountains of Victoria Land using GPS carrier phase measurements. Station monumentation, antenna mounts, antenna types, and data processing strategies were optimized to achieve mm-level estimates for the rates of motion. These data contributes also to regional Antarctic frame definition. Significant amount of data collected over several years allow the investigation of unique aspects of GPS geodesy in Antarctica, to determine how the error spectrum compares to the mid-latitude regions, and to identify the optimum measurement and data processing schemes for Antarctic conditions, in order to test the predicted rates of motion (mm-level w.r.t. time). The data collection for the TAMDEF project was initiated in 1996. The primary antenna used has been the Ashtech L1/L2 Dorne Margolin (D/M) choke ring. A few occupations involved the use of a Trimble D/M choke ring. The data were processed using the antenna calibration data available from the National Geodetic Survey (NGS). The recent developments in new antenna designs that are lighter in weight and lower in cost are being considered as a possible alternative to the bulkier and more expensive D/M choke ring design. In November 2003, in situ testing of three alternative models of L1/L2 antennas was conducted at a site located in the vicinity of McMurdo Station, Antarctica (S77.87, E166.56). The antenna models used in this test were: Ashtech D/M choke ring, Trimble D/M choke ring, Trimble Zephyr, and the NovAtel GPS-702. Two stations, spaced within 30 meters, were used in the test. Both had the characteristics similar to the stations of the TAMDEF network, i.e., the UNAVCO fixed-height, force-centered level mounts with a constant antenna offset were used, ensuring extreme stability of the antenna/ mount/pin set up. During each of the four 3-day test data collection

  2. Integrated Science and Logistical Planning to Support Big Questions in Antarctic Science

    Science.gov (United States)

    Vaughan, D. G.; Stockings, T. M.

    2015-12-01

    Each year, British Antarctic Survey (BAS) supports an extensive programme of science at five Antarctic and sub-Antarctic stations, ranging from the tiny Bird Island Research Station at 54°S in the South Atlantic, to the massive, and fully re-locatable, Halley Research Station on Brunt Ice Shelf at 75°S. The BAS logistics hub, Rothera Research Station on the Antarctic Peninsula supports deployment of deep-field and airborne field campaigns through much of the Antarctic continent, and an innovative new UK polar research vessel is under design, and planned to enter service in the Southern Ocean in 2019. BAS's core science programme covering all aspects of physical, biological and geological science is delivered by our own science teams, but every year many other UK scientists and overseas collaborators also access BAS's Antarctic logistics to support their own programmes. As an integrated science and logistics provider, BAS is continuously reviewing its capabilities and operational procedures to ensure that the future long-term requirements of science are optimally supported. Current trends are towards providing the capacity for heavier remote operations and larger-scale field camps, increasing use of autonomous ocean and airborne platforms, and increasing opportunities to provide turnkey solutions for low-cost experimental deployments. This talk will review of expected trends in Antarctic science and the opportunities to conduct science in Antarctica. It will outline the anticipated logistic developments required to support future stakeholder-led and strategically-directed science programmes, and the long-term ambitions of our science communities indentified in several recent horizon-scanning activities.

  3. The Effects of Interactive Stratospheric Chemistry on Antarctic and Southern Ocean Climate Change in an AOGCM

    Science.gov (United States)

    Li, Feng; Newman, Paul; Pawson, Steven; Waugh, Darryn

    2014-01-01

    Stratospheric ozone depletion has played a dominant role in driving Antarctic climate change in the last decades. In order to capture the stratospheric ozone forcing, many coupled atmosphere-ocean general circulation models (AOGCMs) prescribe the Antarctic ozone hole using monthly and zonally averaged ozone field. However, the prescribed ozone hole has a high ozone bias and lacks zonal asymmetry. The impacts of these biases on model simulations, particularly on Southern Ocean and the Antarctic sea ice, are not well understood. The purpose of this study is to determine the effects of using interactive stratospheric chemistry instead of prescribed ozone on Antarctic and Southern Ocean climate change in an AOGCM. We compare two sets of ensemble simulations for the 1960-2010 period using different versions of the Goddard Earth Observing System 5 - AOGCM: one with interactive stratospheric chemistry, and the other with prescribed monthly and zonally averaged ozone and 6 other stratospheric radiative species calculated from the interactive chemistry simulations. Consistent with previous studies using prescribed sea surface temperatures and sea ice concentrations, the interactive chemistry runs simulate a deeper Antarctic ozone hole and consistently larger changes in surface pressure and winds than the prescribed ozone runs. The use of a coupled atmosphere-ocean model in this study enables us to determine the impact of these surface changes on Southern Ocean circulation and Antarctic sea ice. The larger surface wind trends in the interactive chemistry case lead to larger Southern Ocean circulation trends with stronger changes in northerly and westerly surface flow near the Antarctica continent and stronger upwelling near 60S. Using interactive chemistry also simulates a larger decrease of sea ice concentrations. Our results highlight the importance of using interactive chemistry in order to correctly capture the influences of stratospheric ozone depletion on climate

  4. Demonstration of “substantial research activity” to acquire consultative status under the Antarctic Treaty

    Directory of Open Access Journals (Sweden)

    Andrew D. Gray

    2016-12-01

    Full Text Available Antarctic Treaty Consultative Parties are entitled to participate in consensus-based governance of the continent through the annual Antarctic Treaty Consultative Meetings. To acquire consultative status, an interested Party must demonstrate “substantial research activity,” but no agreed mechanism exists to determine whether a Party has fulfilled this criterion. Parties have generally demonstrated substantial research activity with the construction of a research station, as suggested within the Treaty itself. However, this largely demonstrates logistical capacity, rather than research activity, and often results in major and persistent impacts on Antarctic terrestrial environments. Our study found that national investment in Antarctic infrastructure, estimated by the number of bed spaces at stations, was not a reliable indicator of scientific output. Therefore, we investigated metrics to evaluate research activity directly, and identified both the overall number of Antarctic papers and the proportion of national scientific output these represented as meaningful metrics. Such metrics could (1 demonstrate a nation's level of research activity in Antarctica or (2 help Consultative Parties assess the level of research activity undertaken by a Party seeking to acquire consultative status. Our data showed that, even without land-based Antarctic infrastructure, Canada, Denmark and Switzerland may have reasonable grounds to demonstrate “substantial research activity” on a level comparable with existing Consultative Parties. The use of these metrics may help dispel any perceived requirement for the establishment of a research station to reach consultative status, by putting a greater emphasis on generation of scientific research outputs rather than construction of Antarctic infrastructure.

  5. The use of drilling by the U.S. Antarctic program

    Energy Technology Data Exchange (ETDEWEB)

    Wade, M.C.; Webb, J.W.; Hedberg, W.H.

    1994-08-01

    This report on drilling in the Antarctic has been prepared by the U.S. National Science Foundation (NSF) to assist principal investigators and others in complying with the National Environmental Policy Act (NEPA) and the Antarctic Treaty of 1961. Implementing regulations for NEPA are spelled out in 40 CFR 1500-1508. Environmental protection under the Antarctic Treaty is addressed in the Protocol on Environmental Protection to the Antarctic Treaty (hereafter referred to as the Protocol), which was adopted by 26 countries in 1991. In the United States, responsibility for compliance with these requirements rests with the NSF Office of Polar Programs (OPP), which manages the U.S. Antarctic Program (USAP). The USAP recognizes the potentially profound impacts that its presence and activities can have on the antarctic environment. In its extensive support of operations and research in Antarctica, the USAP uses all practical means to foster and maintain natural conditions while supporting scientific endeavors in a safe and healthful manner. Reducing human impacts on the antarctic environment is a major goal of the USAP. The USAP`s operating philosophy is based on broad yet reasonable and practical assumptions concerning environmental protection. The USAP maintains three year-round stations on the continent to support scientific research. Research and associated support operations at these stations and camps sometimes involve drilling into ice, soil, or ocean sediments. In order to comply with NEPA and the Protocol, it is necessary for principal investigators and others to assess the environmental effects of drilling. This report has been prepared to assist in this process by describing various drilling technologies currently available for use in Antarctica, generally characterizing the potential environmental impacts associated with these drilling techniques, and identifying possible mitigation measures to reduce impacts.

  6. Modelling the effects of environmental conditions on the acoustic occurrence and behaviour of Antarctic blue whales.

    Science.gov (United States)

    Shabangu, Fannie W; Yemane, Dawit; Stafford, Kathleen M; Ensor, Paul; Findlay, Ken P

    2017-01-01

    Harvested to perilously low numbers by commercial whaling during the past century, the large scale response of Antarctic blue whales Balaenoptera musculus intermedia to environmental variability is poorly understood. This study uses acoustic data collected from 586 sonobuoys deployed in the austral summers of 1997 through 2009, south of 38°S, coupled with visual observations of blue whales during the IWC SOWER line-transect surveys. The characteristic Z-call and D-call of Antarctic blue whales were detected using an automated detection template and visual verification method. Using a random forest model, we showed the environmental preferences pattern, spatial occurrence and acoustic behaviour of Antarctic blue whales. Distance to the southern boundary of the Antarctic Circumpolar Current (SBACC), latitude and distance from the nearest Antarctic shores were the main geographic predictors of blue whale call occurrence. Satellite-derived sea surface height, sea surface temperature, and productivity (chlorophyll-a) were the most important environmental predictors of blue whale call occurrence. Call rates of D-calls were strongly predicted by the location of the SBACC, latitude and visually detected number of whales in an area while call rates of Z-call were predicted by the SBACC, latitude and longitude. Satellite-derived sea surface height, wind stress, wind direction, water depth, sea surface temperatures, chlorophyll-a and wind speed were important environmental predictors of blue whale call rates in the Southern Ocean. Blue whale call occurrence and call rates varied significantly in response to inter-annual and long term variability of those environmental predictors. Our results identify the response of Antarctic blue whales to inter-annual variability in environmental conditions and highlighted potential suitable habitats for this population. Such emerging knowledge about the acoustic behaviour, environmental and habitat preferences of Antarctic blue whales is

  7. Penguin eggshell membranes reflect homogeneity of mercury in the marine food web surrounding the Antarctic Peninsula

    Energy Technology Data Exchange (ETDEWEB)

    Brasso, Rebecka L., E-mail: rlb1196@uncw.edu [University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 South College Road, Wilmington, NC 28403 (United States); Polito, Michael J. [University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 South College Road, Wilmington, NC 28403 (United States); Lynch, Heather J. [Ecology and Evolution Department, 640 Life Sciences Bldg., Stony Brook University, Stony Brook, NY 11794 (United States); Naveen, R. [Oceanites Inc., PO Box 15259, Chevy Chase, MD 20825 (United States); Emslie, Steven D. [University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 South College Road, Wilmington, NC 28403 (United States)

    2012-11-15

    Remote regions such as the Antarctic have become increasingly important for investigations into far-reaching anthropogenic impacts on the environment, most recently in regard to the global mercury cycle. Spatial patterns of mercury availability in four regions of the Antarctic Peninsula were investigated using three species of sympatrically breeding Pygoscelis penguins as biomonitors. Eggshells with intact membranes from Adelie, Gentoo, and Chinstrap penguins were collected at 24 breeding colonies in the South Orkney Islands, South Shetland Islands, eastern Antarctic Peninsula, and western Antarctic Peninsula during the 2006/2007 austral summer. In addition, we compared eggshell membrane mercury concentrations with eggshell stable isotope values ({delta}{sup 15}N and {delta}{sup 13}C) to determine if species-specific trophic or foraging habitat preferences influenced female mercury exposure prior to breeding. With few exceptions, mercury concentrations were found to be fairly homogeneous throughout the Antarctic Peninsula suggesting little spatial variation in the risk of exposure to dietary mercury in this food web. Mercury concentrations in Gentoo and Adelie penguins were similar while Chinstrap penguins tended to have higher eggshell membrane mercury concentrations than their congeners. However, inter and intra-specific differences in eggshell membrane mercury concentration were not related to eggshell {delta}{sup 15}N or {delta}{sup 13}C values, a likely result of all three species foraging at similar trophic positions. The lack of regional-scale differences in mercury availability in this marine ecosystem may be a reflection of generally uniform atmospheric deposition and upwelling of regionally homogeneous deep water rather than from geographically distinct point sources. -- Highlights: Black-Right-Pointing-Pointer We examined regional patterns of mercury availability in the Antarctic Peninsula. Black-Right-Pointing-Pointer Three species of Pygoscelis

  8. Penguin eggshell membranes reflect homogeneity of mercury in the marine food web surrounding the Antarctic Peninsula

    International Nuclear Information System (INIS)

    Brasso, Rebecka L.; Polito, Michael J.; Lynch, Heather J.; Naveen, R.; Emslie, Steven D.

    2012-01-01

    Remote regions such as the Antarctic have become increasingly important for investigations into far-reaching anthropogenic impacts on the environment, most recently in regard to the global mercury cycle. Spatial patterns of mercury availability in four regions of the Antarctic Peninsula were investigated using three species of sympatrically breeding Pygoscelis penguins as biomonitors. Eggshells with intact membranes from Adélie, Gentoo, and Chinstrap penguins were collected at 24 breeding colonies in the South Orkney Islands, South Shetland Islands, eastern Antarctic Peninsula, and western Antarctic Peninsula during the 2006/2007 austral summer. In addition, we compared eggshell membrane mercury concentrations with eggshell stable isotope values (δ 15 N and δ 13 C) to determine if species-specific trophic or foraging habitat preferences influenced female mercury exposure prior to breeding. With few exceptions, mercury concentrations were found to be fairly homogeneous throughout the Antarctic Peninsula suggesting little spatial variation in the risk of exposure to dietary mercury in this food web. Mercury concentrations in Gentoo and Adélie penguins were similar while Chinstrap penguins tended to have higher eggshell membrane mercury concentrations than their congeners. However, inter and intra-specific differences in eggshell membrane mercury concentration were not related to eggshell δ 15 N or δ 13 C values, a likely result of all three species foraging at similar trophic positions. The lack of regional-scale differences in mercury availability in this marine ecosystem may be a reflection of generally uniform atmospheric deposition and upwelling of regionally homogeneous deep water rather than from geographically distinct point sources. -- Highlights: ► We examined regional patterns of mercury availability in the Antarctic Peninsula. ► Three species of Pygoscelis penguins were used as biomonitors. ► Chinstrap penguins tended to have higher mercury

  9. Modelling the effects of environmental conditions on the acoustic occurrence and behaviour of Antarctic blue whales.

    Directory of Open Access Journals (Sweden)

    Fannie W Shabangu

    Full Text Available Harvested to perilously low numbers by commercial whaling during the past century, the large scale response of Antarctic blue whales Balaenoptera musculus intermedia to environmental variability is poorly understood. This study uses acoustic data collected from 586 sonobuoys deployed in the austral summers of 1997 through 2009, south of 38°S, coupled with visual observations of blue whales during the IWC SOWER line-transect surveys. The characteristic Z-call and D-call of Antarctic blue whales were detected using an automated detection template and visual verification method. Using a random forest model, we showed the environmental preferences pattern, spatial occurrence and acoustic behaviour of Antarctic blue whales. Distance to the southern boundary of the Antarctic Circumpolar Current (SBACC, latitude and distance from the nearest Antarctic shores were the main geographic predictors of blue whale call occurrence. Satellite-derived sea surface height, sea surface temperature, and productivity (chlorophyll-a were the most important environmental predictors of blue whale call occurrence. Call rates of D-calls were strongly predicted by the location of the SBACC, latitude and visually detected number of whales in an area while call rates of Z-call were predicted by the SBACC, latitude and longitude. Satellite-derived sea surface height, wind stress, wind direction, water depth, sea surface temperatures, chlorophyll-a and wind speed were important environmental predictors of blue whale call rates in the Southern Ocean. Blue whale call occurrence and call rates varied significantly in response to inter-annual and long term variability of those environmental predictors. Our results identify the response of Antarctic blue whales to inter-annual variability in environmental conditions and highlighted potential suitable habitats for this population. Such emerging knowledge about the acoustic behaviour, environmental and habitat preferences of

  10. Designing an effective mark-recapture study of Antarctic blue whales.

    Science.gov (United States)

    Peel, David; Bravington, Mark; Kelly, Natalie; Double, Michael C

    2015-06-01

    To properly conserve and manage wild populations, it is important to have information on abundance and population dynamics. In the case of rare and cryptic species, especially in remote locations, surveys can be difficult and expensive, and run the risk of not producing sample sizes large enough to produce precise estimates. Therefore, it is crucial to conduct preliminary analysis to determine if the study will produce useable estimates. The focus of this paper is a proposed mark-recapture study of Antarctic blue whales (Balaenoptera musculus intermedia). Antarctic blue whales were hunted to near extinction up until the mid- 1960s, when commercial exploitation of this species ended. Current abundance estimates are a decade old. Furthermore, at present, there are no formal circumpolar-level cetacean surveys operating in Antarctic waters and, specifically, there is no strategy to monitor the potential recovery of Antarctic blue whales. Hence the work in this paper was motivated by the need to inform decisions on strategies for future monitoring of Antarctic blue whale population. The paper describes a model to predict the precision and bias of estimates from a proposed survey program. The analysis showed that mark-recapture is indeed a suitable method to provide a circumpolar abundance estimate of Antarctic blue whales, with precision of the abundance, at the midpoint of the program, predicted to be between 0.2 and 0.3. However, this was only if passive acoustic tracking was utilized to increase the encounter rate. The analysis also provided guidance on general design for an Antarctic blue whale program, showing that it requires a 12-year duration; although surveys do not necessarily need to be run every year if multiple vessels are available to clump effort. Mark-recapture is based on a number of assumptions; it was evident from the analysis that ongoing analysis and monitoring of the data would be required to check such assumptions hold (e.g., test for

  11. Three dimensional Lagrangian structures in the Antarctic Polar Vortex.

    Science.gov (United States)

    Mancho, Ana M.; Garcia-Garrido, Victor J.; Curbelo, Jezabel; Niang, Coumba; Mechoso, Carlos R.; Wiggins, Stephen

    2017-04-01

    Dynamical systems theory has supported the description of transport processes in fluid dynamics. For understanding trajectory patterns in chaotic advection the geometrical approach by Poincaré seeks for spatial structures that separate regions corresponding to qualitatively different types of trajectories. These structures have been referred to as Lagrangian Coherent Structures (LCS), which typically in geophysical flows are well described under the approach of incompressible 2D flows. Different tools have been used to visualize LCS. In this presentation we use Lagrangian Descriptors [1,2,3,4] (function M) for visualizing 3D Lagrangian structures in the atmosphere, in particular in the Antarctic Polar Vortex. The function M is computed in a fully 3D incompressible flow obtained from data provided by the European Centre for Medium-Range Weather Forecast and it is represented in 2D surfaces. We discuss the findings during the final warming that took place in the spring of 1979 [5]. This research is supported by MINECO grant MTM2014-56392-R. Support is acknowledged also from CSIC grant COOPB20265, U.S. NSF grant AGS-1245069 and ONR grant No. N00014- 01-1-0769. C. Niang acknowledges Fundacion Mujeres por Africa and ICMAT Severo Ochoa project SEV-2011-0087 for financial support. [1] C. Mendoza, A. M. Mancho. The hidden geometry of ocean flows. Physical Review Letters 105 (2010), 3, 038501-1-038501-4. [2] A. M. Mancho, S. Wiggins, J. Curbelo, C. Mendoza. Lagrangian Descriptors: A Method for Revealing Phase Space Structures of General Time Dependent Dynamical Systems. Communications in Nonlinear Science and Numerical Simulation. 18 (2013) 3530-3557. [3] C. Lopesino, F. Balibrea-Iniesta, S. Wiggins and A. M. Mancho. Lagrangian descriptors for two dimensional, area preserving autonomous and nonautonomous maps. Communications in Nonlinear Science and Numerical Simulations, 27 (2015) (1-3), 40-51. [4] C. Lopesino, F. Balibrea-Iniesta, V. J. García-Garrido, S. Wiggins, and A

  12. Overview of mercury measurements in the Antarctic troposphere

    Directory of Open Access Journals (Sweden)

    A. Dommergue

    2010-04-01

    may be recycled. Therefore, the contribution of this unique reactivity occurring in polar atmospheres to the global budget of atmospheric mercury, and the role played by snow and ice surfaces of these regions, are important issues. This paper presents a review of atmospheric mercury studies conducted in the Antarctic troposphere, both at coastal locations and on the Antarctic Plateau since 1985. Our current understanding of atmospheric reactivity in this region is also presented.

  13. Antarctic Intermediate Water Formation in a High-Resolution OGCM

    Science.gov (United States)

    Fetter, Antonio; Schodlok, Michael; Zlotnicki, Victor

    2010-05-01

    The importance of the Antarctic Circumpolar Current (ACC), and the Southern Ocean, in the Climate System, has become apparent in the last decades. Water masses formed at these high latitudes are linked to the shallow and deep branches of the meridional overturning circulation. The Antarctic Intermediate Water (AAIW), as the main water mass ventilating the base of the worlds ocean thermocline, plays a central role not only in the climate system dynamics, but also in the global cycles of carbon dioxide and other bio-geochemical tracers. The mechanisms AAIW formation, as well as, the relationship among the rate of formation of the AAIW, the ACC frontal locations and mesoscale activity at the fronts are investigated in this study. Thus, in this research the output of the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project is used. It is a global high-resolution data synthesis in space and time, that is obtained through an orthogonal projection of the Massachusetts Institute of Technology general circulation model (MITgcm) onto available satellite and in-situ data. During winter, deep mixed layers (ML) of up to 600 m are formed as a result of deep convection. In turn, the deep ML are the nursery grounds for the Subantarctic Mode Water (SAMW), the lighter precursor of the AAIW. Diapycnal transformation of AAIW, due to internal mixing and air-sea interactions, is found to occur mainly in the South Pacific Ocean, which is known to be one of the most important regions for AAIW transformation. However, significant AAIW transformation is also observed in the South Indian Ocean. In ECCO2, AAIW is represented for by the water masses within the 27-27.8 kg m-3 neutral density range. While the heaviest AAIW (27.4-27.8 kg.m-3) is formed in the South Indian Ocean, reaching a peak production of about 40Sv during late July, the lighter version of the AAIW (27-27.4 kg.m-3) is mainly produced in the South Pacific Ocean. We found that eddy fluxes efficiently

  14. On two Antarctic species of Oswaldella Stechow, 1919: O. shetlandica Stepan'yants, 1979 and O. elongata spec. nov. (Cnidaria Hydrozoa) (Notes on Antarctic hydroids, II)

    NARCIS (Netherlands)

    Peña Cantero, A.L.; García Carrascosa, A.M.; Vervoort, W.

    1995-01-01

    Two species of the antarctic hydroid genus Oswaldella Stechow, 1919, are considered. The first, described by Stepan'yants (1979) as a subspecies, O. billardi shetlandica, has been raised to specific level and will henceforth be indicated as Oswaldella shetlandica Stepan'yants, 1979. A second species

  15. An Sp1/Sp3 binding polymorphism confers methylation protection.

    Directory of Open Access Journals (Sweden)

    Yanis A Boumber

    2008-08-01

    Full Text Available Hundreds of genes show aberrant DNA hypermethylation in cancer, yet little is known about the causes of this hypermethylation. We identified RIL as a frequent methylation target in cancer. In search for factors that influence RIL hypermethylation, we found a 12-bp polymorphic sequence around its transcription start site that creates a long allele. Pyrosequencing of homozygous tumors revealed a 2.1-fold higher methylation for the short alleles (P<0.001. Bisulfite sequencing of cancers heterozygous for RIL showed that the short alleles are 3.1-fold more methylated than the long (P<0.001. The comparison of expression levels between unmethylated long and short EBV-transformed cell lines showed no difference in expression in vivo. Electrophorectic mobility shift assay showed that the inserted region of the long allele binds Sp1 and Sp3 transcription factors, a binding that is absent in the short allele. Transient transfection of RIL allele-specific transgenes showed no effects of the additional Sp1 site on transcription early on. However, stable transfection of methylation-seeded constructs showed gradually decreasing transcription levels from the short allele with eventual spreading of de novo methylation. In contrast, the long allele showed stable levels of expression over time as measured by luciferase and approximately 2-3-fold lower levels of methylation by bisulfite sequencing (P<0.001, suggesting that the polymorphic Sp1 site protects against time-dependent silencing. Our finding demonstrates that, in some genes, hypermethylation in cancer is dictated by protein-DNA interactions at the promoters and provides a novel mechanism by which genetic polymorphisms can influence an epigenetic state.

  16. Revised Macquarie-Antarctic plate motion during the last 6 Ma using magnetic anomalies of Australian-Antarctic Ridge near 156°-161°E

    Science.gov (United States)

    Choi, H.; Kim, S. S.; Park, S. H.

    2015-12-01

    The longest segment of Australian-Antarctic Ridge (AAR), located near 156°-161°E, is the tectonic boundary between the Australian and the Antarctic plates, and meets the Macquarie Triple Junction of Australian-Antarctic-Pacific plates at the eastern end of the segment. In 2011 and 2013, the multidisciplinary mid-ocean ridge program of Korea Polar Research Institute (KOPRI) conducted a series of geological, geochemical, geophysical, and hydrothermal studies at the segment. Especially, in order to determine the detailed location of the ridge axis, a number of short magnetic cross lines were observed in 2013. In 2015, we additionally collected the magnetic data and the high-resolution shipboard bathymetric data for two 400-km long lines across the ridge segment. Here we utilize the observed magnetic data to estimate spreading rates and its temporal changes along the ridge segment. The half-spreading rates computed using MODMAG with our magnetic data range mostly between 28~34 mm/yr. The southern flank of this ridge segment, which has been added to the Antarctic plate as a trailing side between the Australian and the Antarctic plate, tends to have faster spreading rates compared to the northern flank. According to the previous studies, the Macquarie plate, which is regarded as the intra-plate inside the Australian plate and bounded by the northern flank of the ridge segment in this study, has been rotated relative to the Antarctic plate since about 6 Ma. We revised rotation poles between the Macquarie-Antarctic plates for the chron C2Ay (2.58 Ma), chron C3Ay (6.04 Ma) and the other ages additionally, using Hellinger. In this study, we employed the observed magnetic data with additional constraints from the available shipboard measurements. The synthetic flow-line of Balleny Fracture Zone is used as an input to Hellinger, because the region between the Tasman Fracture Zone and the Macquarie Triple Junction is supposed to be included to the Macquarie plate. We examine

  17. Antarctic Circumpolar Current Dynamics and Their Relation to Antarctic Ice Sheet and Perennial Sea-Ice Variability in the Central Drake Passage During the Last Climate Cycle

    Science.gov (United States)

    Kuhn, G.; Wu, S.; Hass, H. C.; Klages, J. P.; Zheng, X.; Arz, H. W.; Esper, O.; Hillenbrand, C. D.; Lange, C.; Lamy, F.; Lohmann, G.; Müller, J.; McCave, I. N. N.; Nürnberg, D.; Roberts, J.; Tiedemann, R.; Timmermann, A.; Titschack, J.; Zhang, X.

    2017-12-01

    The evolution of the Antarctic Ice Sheet during the last climate cycle and the interrelation to global atmospheric and ocean circulation remains controversial and plays an important role for our understanding of ice sheet response to modern global warming. The timing and sequence of deglacial warming is relevant for understanding the variability and sensitivity of the Antarctic Ice Sheet to climatic changes, and the continuing rise of atmospheric greenhouse gas concentrations. The Antarctic Ice Sheet is a pivotal component of the global water budget. Freshwater fluxes from the ice sheet may affect the Antarctic Circumpolar Current (ACC), which is strongly impacted by the westerly wind belt in the Southern Hemisphere (SHWW) and constricted to its narrowest extent in the Drake Passage. The flow of ACC water masses through Drake Passage is, therefore, crucial for advancing our understanding of the Southern Ocean's role in global meridional overturning circulation and global climate change. In order to address orbital and millennial-scale variability of the Antarctic ice sheet and the ACC, we applied a multi-proxy approach on a sediment core from the central Drake Passage including grain size, iceberg-rafted debris, mineral dust, bulk chemical and mineralogical composition, and physical properties. In combination with already published and new sediment records from the Drake Passage and Scotia Sea, as well as high-resolution data from Antarctic ice cores (WDC, EDML), we now have evidence that during glacial times a more northerly extent of the perennial sea-ice zone decreased ACC current velocities in the central Drake Passage. During deglaciation the SHWW shifted southwards due to a decreasing temperature gradient between subtropical and polar latitudes caused by sea ice and ice sheet decline. This in turn caused Southern Hemisphere warming, a more vigorous ACC, stronger Southern Ocean ventilation, and warm Circumpolar Deep Water (CDW) upwelling on Antarctic shelves

  18. Antioxidant capacity, polyphenol content and iron bioavailability from algae (Ulva sp., Sargassum sp. and Porphyra sp.) in human subjects.

    Science.gov (United States)

    García-Casal, Maria N; Ramírez, José; Leets, Irene; Pereira, Ana C; Quiroga, Maria F

    2009-01-01

    Marine algae are easily produced and are good sources of Fe. If this Fe is bioavailable, algae consumption could help to combat Fe deficiency and anaemia worldwide. The objective of the present study was to evaluate Fe bioavailability, polyphenol content and antioxidant capacity from three species of marine algae distributed worldwide. A total of eighty-three subjects received maize- or wheat-based meals containing marine algae (Ulva sp., Sargassum sp. and Porphyra sp.) in different proportions (2.5, 5.0 and 7.5 g) added to the water to prepare the dough. All meals administered contained radioactive Fe. Absorption was evaluated calculating radioactive Fe incorporation in subjects' blood. The three species of marine algae were analysed for polyphenol content and reducing power. Algae significantly increased Fe absorption in maize- or wheat-based meals, especially Sargassum sp., due to its high Fe content. Increases in absorption were dose-dependent and higher in wheat- than in maize-based meals. Total polyphenol content was 10.84, 18.43 and 80.39 gallic acid equivalents/g for Ulva sp., Porphyra sp. and Sargassum sp., respectively. The antioxidant capacity was also significantly higher in Sargassum sp. compared with the other two species analysed. Ulva sp., Sargassum sp. and Porphyra sp. are good sources of bioavailable Fe. Sargassum sp. resulted in the highest Fe intake due to its high Fe content, and a bread containing 7.5 g Sargassum sp. covers daily Fe needs. The high polyphenol content found in Sargassum sp. could be partly responsible for the antioxidant power reported here, and apparently did not affect Fe absorption.

  19. Antarctic climate variability on regional and continental scales over the last 2000 years

    Science.gov (United States)

    Stenni, Barbara; Curran, Mark A. J.; Abram, Nerilie J.; Orsi, Anais; Goursaud, Sentia; Masson-Delmotte, Valerie; Neukom, Raphael; Goosse, Hugues; Divine, Dmitry; van Ommen, Tas; Steig, Eric J.; Dixon, Daniel A.; Thomas, Elizabeth R.; Bertler, Nancy A. N.; Isaksson, Elisabeth; Ekaykin, Alexey; Werner, Martin; Frezzotti, Massimo

    2017-11-01

    Climate trends in the Antarctic region remain poorly characterized, owing to the brevity and scarcity of direct climate observations and the large magnitude of interannual to decadal-scale climate variability. Here, within the framework of the PAGES Antarctica2k working group, we build an enlarged database of ice core water stable isotope records from Antarctica, consisting of 112 records. We produce both unweighted and weighted isotopic (δ18O) composites and temperature reconstructions since 0 CE, binned at 5- and 10-year resolution, for seven climatically distinct regions covering the Antarctic continent. Following earlier work of the Antarctica2k working group, we also produce composites and reconstructions for the broader regions of East Antarctica, West Antarctica and the whole continent. We use three methods for our temperature reconstructions: (i) a temperature scaling based on the δ18O-temperature relationship output from an ECHAM5-wiso model simulation nudged to ERA-Interim atmospheric reanalyses from 1979 to 2013, and adjusted for the West Antarctic Ice Sheet region to borehole temperature data, (ii) a temperature scaling of the isotopic normalized anomalies to the variance of the regional reanalysis temperature and (iii) a composite-plus-scaling approach used in a previous continent-scale reconstruction of Antarctic temperature since 1 CE but applied to the new Antarctic ice core database. Our new reconstructions confirm a significant cooling trend from 0 to 1900 CE across all Antarctic regions where records extend back into the 1st millennium, with the exception of the Wilkes Land coast and Weddell Sea coast regions. Within this long-term cooling trend from 0 to 1900 CE, we find that the warmest period occurs between 300 and 1000 CE, and the coldest interval occurs from 1200 to 1900 CE. Since 1900 CE, significant warming trends are identified for the West Antarctic Ice Sheet, the Dronning Maud Land coast and the Antarctic Peninsula regions, and these

  20. Antarctic climate variability on regional and continental scales over the last 2000 years

    Directory of Open Access Journals (Sweden)

    B. Stenni

    2017-11-01

    Full Text Available Climate trends in the Antarctic region remain poorly characterized, owing to the brevity and scarcity of direct climate observations and the large magnitude of interannual to decadal-scale climate variability. Here, within the framework of the PAGES Antarctica2k working group, we build an enlarged database of ice core water stable isotope records from Antarctica, consisting of 112 records. We produce both unweighted and weighted isotopic (δ18O composites and temperature reconstructions since 0 CE, binned at 5- and 10-year resolution, for seven climatically distinct regions covering the Antarctic continent. Following earlier work of the Antarctica2k working group, we also produce composites and reconstructions for the broader regions of East Antarctica, West Antarctica and the whole continent. We use three methods for our temperature reconstructions: (i a temperature scaling based on the δ18O–temperature relationship output from an ECHAM5-wiso model simulation nudged to ERA-Interim atmospheric reanalyses from 1979 to 2013, and adjusted for the West Antarctic Ice Sheet region to borehole temperature data, (ii a temperature scaling of the isotopic normalized anomalies to the variance of the regional reanalysis temperature and (iii a composite-plus-scaling approach used in a previous continent-scale reconstruction of Antarctic temperature since 1 CE but applied to the new Antarctic ice core database. Our new reconstructions confirm a significant cooling trend from 0 to 1900 CE across all Antarctic regions where records extend back into the 1st millennium, with the exception of the Wilkes Land coast and Weddell Sea coast regions. Within this long-term cooling trend from 0 to 1900 CE, we find that the warmest period occurs between 300 and 1000 CE, and the coldest interval occurs from 1200 to 1900 CE. Since 1900 CE, significant warming trends are identified for the West Antarctic Ice Sheet, the Dronning Maud Land coast and the

  1. Quantarctica: A Unique, Open, Standalone GIS Package for Antarctic Research and Education

    Science.gov (United States)

    Roth, George; Matsuoka, Kenichi; Skoglund, Anders; Melvær, Yngve; Tronstad, Stein

    2017-04-01

    The Norwegian Polar Institute has developed Quantarctica (http://quantarctica.npolar.no), an open GIS package for use by the international Antarctic community. Quantarctica includes a wide range of cartographic basemap layers, geophysical and glaciological datasets, and satellite imagery in standardized open file formats with a consistent Antarctic map projection and customized layer and labeling styles for quick, effective cartography. Quantarctica's strengths as an open science platform lie in 1) The complete, ready-to-use data package which includes full-resolution, original-quality vector and raster data, 2) A policy for freely-redistributable and modifiable data including all metadata and citations, and 3) QGIS, a free, full-featured, modular, offline-capable open-source GIS suite with a rapid and active development and support community. The Quantarctica team is actively incorporating more up-to-date, peer-reviewed, freely distributable pan-Antarctic geospatial datasets for the next version release in 2017. As part of this ongoing development, we are investigating the best approaches for quickly and seamlessly distributing new and updated data to users, storing datasets in efficient, open file formats while maintaining full data integrity, and coexisting with numerous online data portals in a way that most actively benefits the Antarctic community. A recent survey of Quantarctica users showed broad geographical adoption among Antarctic Treaty countries, including those outside the large US and UK Antarctic programs. Maps and figures produced by Quantarctica have also appeared in open-access journals and outside of the formal scientific community on popular science and GIS blogs. Our experience with the Quantarctica project has shown the tremendous value of education and outreach, not only in promoting open software, data formats, and practices, but in empowering Antarctic science groups to more effectively use GIS and geospatial data. Open practices are

  2. A New Thermophilic Nitrilase from an Antarctic Hyperthermophilic Microorganism

    OpenAIRE

    Dennett, Geraldine V.; Blamey, Jenny M.

    2016-01-01

    Several environmental samples from Antarctica were collected and enriched to search for microorganisms with nitrilase activity. A new thermostable nitrilase from a novel hyperthermophilic archaea Pyrococcus sp. M24D13 was purified and characterized. The activity of this enzyme increased as the temperatures rise from 70 up to 85?C. Its optimal activity occurred at 85?C and pH 7.5. This new enzyme shows a remarkable resistance to thermal inactivation retaining more than 50% of its activity even...

  3. Antarctic air over New Zealand following vortex breakdown in 1998

    Directory of Open Access Journals (Sweden)

    J. Ajtic

    2003-11-01

    Full Text Available An ozonesonde profile over the Network for Detection of Stratospheric Change (NDSC site at Lauder (45.0° S, 169.7° E, New Zealand, for 24 December 1998 showed atypically low ozone centered around 24 km altitude (600 K potential temperature. The origin of the anomaly is explained using reverse domain filling (RDF calculations combined with a PV/O3 fitting technique applied to ozone measurements from the Polar Ozone and Aerosol Measurement (POAM III instrument. The RDF calculations for two isentropic surfaces, 550 and 600 K, show that ozone-poor air from the Antarctic polar vortex reached New Zealand on 24–26 December 1998. The vortex air on the 550 K isentrope originated in the ozone hole region, unlike the air on 600 K where low ozone values were caused by dynamical effects. High-resolution ozone maps were generated, and their examination shows that a vortex remnant situated above New Zealand was the cause of the altered ozone profile on 24 December. The maps also illustrate mixing of the vortex filaments into southern midlatitudes, whereby the overall mid-latitude ozone levels were decreased.Key words. Atmospheric composition and structure (middle atmosphere composition and chemistry – Meteorology and atmospheric dynamics (middle atmosphere dynamics

  4. Antarctic air over New Zealand following vortex breakdown in 1998

    Directory of Open Access Journals (Sweden)

    J. Ajtic

    Full Text Available An ozonesonde profile over the Network for Detection of Stratospheric Change (NDSC site at Lauder (45.0° S, 169.7° E, New Zealand, for 24 December 1998 showed atypically low ozone centered around 24 km altitude (600 K potential temperature. The origin of the anomaly is explained using reverse domain filling (RDF calculations combined with a PV/O3 fitting technique applied to ozone measurements from the Polar Ozone and Aerosol Measurement (POAM III instrument. The RDF calculations for two isentropic surfaces, 550 and 600 K, show that ozone-poor air from the Antarctic polar vortex reached New Zealand on 24–26 December 1998. The vortex air on the 550 K isentrope originated in the ozone hole region, unlike the air on 600 K where low ozone values were caused by dynamical effects. High-resolution ozone maps were generated, and their examination shows that a vortex remnant situated above New Zealand was the cause of the altered ozone profile on 24 December. The maps also illustrate mixing of the vortex filaments into southern midlatitudes, whereby the overall mid-latitude ozone levels were decreased.

    Key words. Atmospheric composition and structure (middle atmosphere composition and chemistry – Meteorology and atmospheric dynamics (middle atmosphere dynamics

  5. Intermittency on simultaneous observations of riometer at several Antarctic locations

    Science.gov (United States)

    Ovalle, E. M.; Foppiano, A. J.; Stepanova, M. V.; Weatherwax, A. T.

    2016-03-01

    It is well known that auroral radio wave absorption, as measured by riometers, consists of periods of relative quiescence which are interrupted by short bursts of activity. Such patterns in activity are observed in systems ranging from the stock market to turbulence, i.e. they exhibit intermittency. In the case of the auroral absorption it has also been found that intermittency strongly depends on the magnetic local time, being largest in the night-time sector. This can be interpreted as indicating that the precipitating particles responsible of the absorption exhibit intermittency, especially near the substorm eye, where the level of turbulence increases. Here, we analyse simultaneous observations of riometer absorption at seven Antarctic locations, to determine whether they exhibit intermittency. We determine the Probability Distribution Functions of the fluctuations of riometer absorption for absorption events larger than 0.1 dB, as well as those for the time-intervals between absorption events. Observations are for locations within the austral auroral absorption zone and on the polar cap. It is found that the parameters of a power law used to describe the calculated PDFs are consistent with the formation of coherent structures being more frequent within the auroral zone, as a manifestation of intermittency.

  6. Modeling Antarctic Subglacial Lake Filling and Drainage Cycles

    Science.gov (United States)

    Dow, Christine F.; Werder, Mauro A.; Nowicki, Sophie; Walker, Ryan T.

    2016-01-01

    The growth and drainage of active subglacial lakes in Antarctica has previously been inferred from analysis of ice surface altimetry data. We use a subglacial hydrology model applied to a synthetic Antarctic ice stream to examine internal controls on the filling and drainage of subglacial lakes. Our model outputs suggest that the highly constricted subglacial environment of our idealized ice stream, combined with relatively high rates of water flow funneled from a large catchment, can combine to create a system exhibiting slow-moving pressure waves. Over a period of years, the accumulation of water in the ice stream onset region results in a buildup of pressure creating temporary channels, which then evacuate the excess water. This increased flux of water beneath the ice stream drives lake growth. As the water body builds up, it steepens the hydraulic gradient out of the overdeepened lake basin and allows greater flux. Eventually this flux is large enough to melt channels that cause the lake to drain. Lake drainage also depends on the internal hydrological development in the wider system and therefore does not directly correspond to a particular water volume or depth. This creates a highly temporally and spatially variable system, which is of interest for assessing the importance of subglacial lakes in ice stream hydrology and dynamics.

  7. A geoelectrical survey above an Antarctic ice shelf

    Directory of Open Access Journals (Sweden)

    M. Pavan

    1998-06-01

    Full Text Available A geoelectrical survey was performed on the Hells Gate ice shelf (Victoria Land-Antarctic within the framework of an integrated geophysical and glaciological research program. The resistivity profiles show a similar trend, with resistivity values ranging from about 25000 W · m to 500000 W · m. These results have been interpreted as the effect of a sharp transition from "marine ice" to "continental" ice an interpretation that is consistent with the results of surface mapping. Interpreting the Vertical Electrical Soundings (VES is a complex process. In fact, the alternating layers of ice with different compositions and salt content generate great uncertainty relative to the corresponding electric stratigraphies. To solve these problems of equivalency, all the available constraints were used including the drilling thickness, seismic reflection profiles as well as radar profiles. The results were used to provide what is mainly a qualitative overview that is coherent with the glaciological hypotheses relative to the evolution and structure proposed by some researchers for this ice shelf.

  8. Molecular and morphological analysis of an Antarctic tardigrade, Acutuncus antarcticus

    Directory of Open Access Journals (Sweden)

    Hiroshi Kagoshima

    2013-03-01

    Full Text Available We isolated a species of tardigrade from moss samples collected from Langhovde and Skarvsnes, near Syowa station, East Antarctic, from which we cultured a parthenogenetic strain in Petri dishes with co-occurring cyanobacteria or green algae. This culture was maintained at both 4 and 10ºC, though the latter proved more suitable for growth. Eggs were laid free, rather than in exuviae. We isolated the 18S rRNA sequences from this tardigrade, identical to that of Acutuncus antarcticus from King George island, South Shetland islands. Morphological analyses via both light and scanning electron microscopy also show general agreement with characteristics of A. antarcticus: dorsal and ventral apophyses for the insertion of stylet muscles and dorsal longitudinal thickening on the anterior part of buccal tube; presence of pharyngeal apophyses, two macroplacoids and absence of a microplacoid; the surface structure of egg; and claw shape. Peribuccal lamellae were absent, but six oval swellings surrounded the mouth opening. An additional study of moss pillars from lake Hotoke-ike, Skarvsnes, proved the existence of the same tardigrade taxon living at the bottom of the lake.

  9. Pop-like halogenated natural products in antarctic sponges

    Energy Technology Data Exchange (ETDEWEB)

    Vetter, W. [Hohenheim Univ., Stuttgart (Germany); Janussen, D. [Senckenbergische Naturforschende Gesellschaft (Natur-Museum und Forschungs-Institut), Frankfurt am Main (Germany)

    2004-09-15

    Persistent organic pollutants (POPs) are major contaminants of our days. This group of chemicals comprises a number of halogenated compounds used as pesticides (DDT, lindane, chlordane, toxaphene and others) as well as industrial chemicals (PCBs, PCNs, CPs, and brominated flameretardants). Although the list of known POPs including isomers and metabolites is long, there are frequent reports on the detection of unknown organohalogen compounds in the literature. Recent work demonstrated that some of these unknown peaks in gas chromatograms originate from halogenated natural products (HNPs). Sometimes, HNPs have been found at remarkably high concentrations in marine birds, mammals and fish. Due to the structural similarities with anthropogenic POPs, these substances may possess a potential risk for wildlife and man. HNPs are known to be produced with an overwhelming variety by marine organisms such as algae, sponges, microorganisms and others. In this study we have screened different species of Antarctic sponges on the occurrence of halogenated compounds which may be of environmental concern. Thus, we were only interested in lipophilic and persistent HNPs. Following that, we applied our standard sample clean-up procedure for the analysis of nonpolar POPs. Two steps on deactivated and activated silica yielded compounds with similar polarity as PCBs, chloropesticides and brominated analogues in the sample extracts. Additionally, all samples were treated with concentrated sulphuric acid in order to eliminate labile (non-presistent) HNPs.

  10. The role of feedbacks in Antarctic sea ice change

    Science.gov (United States)

    Feltham, D. L.; Frew, R. C.; Holland, P.

    2017-12-01

    The changes in Antarctic sea ice over the last thirty years have a strong seasonal dependence, and the way these changes grow in spring and decay in autumn suggests that feedbacks are strongly involved. The changes may ultimately be caused by atmospheric warming, the winds, snowfall changes, etc., but we cannot understand these forcings without first untangling the feedbacks. A highly simplified coupled sea ice -mixed layer model has been developed to investigate the importance of feedbacks on the evolution of sea ice in two contrasting regions in the Southern Ocean; the Amundsen Sea where sea ice extent has been decreasing, and the Weddell Sea where it has been expanding. The change in mixed layer depth in response to changes in the atmosphere to ocean energy flux is implicit in a strong negative feedback on ice cover changes in the Amundsen Sea, with atmospheric cooling leading to a deeper mixed layer resulting in greater entrainment of warm Circumpolar Deep Water, causing increased basal melting of sea ice. This strong negative feedback produces counter intuitive responses to changes in forcings in the Amundsen Sea. This feedback is absent in the Weddell due to the complete destratification and strong water column cooling that occurs each winter in simulations. The impact of other feedbacks, including the albedo feedback, changes in insulation due to ice thickness and changes in the freezing temperature of the mixed layer, were found to be of secondary importance compared to changes in the mixed layer depth.

  11. Microfossils in the Antarctic cold desert: Possible implications for Mars

    Science.gov (United States)

    Friedmann, E. I.; Ocampo-Friedmann, R.

    1986-01-01

    In the Ross Desert of Antarctica, the principal life form is the cryptoendolithic microbial community in the near-surface layers of porous sandstone rocks. Biological, geological, and climatic factors interact in a complex and precarious balance, making life possible in an otherwise hostile environment. Once this balance is tipped, fossilization sets in. In the reverse case, new colonization of the rock surface may be initiated. As a result, fossilization is contemporary with modern life and both may be simultaneously present in a mosaic pattern. Also, different stages of fossilization are present. The process of fossilization takes place in a nonaquatic environment. If primitive life ever appeared on Mars, it is possible that with increasing aridity, life withdrew into an endolithic niche similar to that in the Antarctic desert. Fossilization in a nonaquatic environment may have set in with the result that traces of past life could be preserved. If such was the case, the study of the fossilization process in Antarctica may hold useful information for the analysis of Martian samples for microfossils.

  12. Shutter heating system of Antarctic bright star survey telescope

    Science.gov (United States)

    Chen, Jie; Dong, Shucheng; Jiang, Fengxin; Zhang, Hongfei; Wang, Jian

    2016-07-01

    A heat preservation system for mechanical shutter in Antarctic is introduced in the paper. The system consists of the heat preservation chamber, the host controller STM32F103C8T6 with peripheral circuit and the control algorithm. The whole design is carried out on the basis of the low temperature requirement, including the cavity structure and thermal insulation. The heat preservation chamber is used to keep the shutter warm and support the weight of the camera. Using PT100 as the temperature sensor, the signal processing circuit converts the temperature to the voltage which is then digitized by the 12 bit ADC in the STM32. The host controller transforms the voltage data into temperature, and through the tuning of the Fussy PID algorithm which controls the duty cycle of the MOSFET, the temperature control of chamber is realized. The System has been tested in the cryogenic environment for a long time, with characteristic of low temperature resistance, small volume, high accuracy of temperature control as well as remote control and detection.

  13. Visual physiology of the Antarctic amphipod Abyssorchomene plebs.

    Science.gov (United States)

    Cohen, Jonathan H; Frank, Tamara M

    2006-10-01

    Although the visual systems of animals living in the cold, dark water of the deep sea have been investigated for some time, little is known about vision in animals inhabiting polar oceans, where temperatures are even colder and irradiance fluctuates dramatically with ice cover and season. Physiology of the compound eye of the amphipod Abyssorchomene plebs (Gammaridea: Lysianassoidea), a common Antarctic benthic scavenger, was studied electrophysiologically by electroretinography. A. plebs has a monochromatic visual system with a spectral sensitivity maximum at 487 nm, and higher sensitivity at ultraviolet wavelengths than predicted by a visual pigment template. While irradiance sensitivity determined from V/log I curves is comparable to that of mesopelagic crustaceans, temporal resolution calculated from response waveform dynamics and as determined by critical flicker fusion frequency suggest that the A. plebs eye is slower than that of crustaceans from the deep sea. A. plebs photoreceptors are physiologically adapted for a slow lifestyle in a low-light environment, where maximizing photon capture occurs at the expense of detecting fast events in the visual scene.

  14. Greenhouse gas emissions from the Brazilian Antarctic Station "Comandante Ferraz".

    Science.gov (United States)

    Leripio, Alexandre de Avila; Torres, João Paulo Machado; Viana, Mariana de Sá; Echelmeier, Gustavo Rohden

    2012-12-01

    Climate change is a natural phenomenon that has been intensified due to increased emissions of greenhouse gases (GHG). It has become an indispensable issue in international negotiations related to global sustainability and is deeply related to the overall status of environmental health in our planet. We compiled an inventory of GHG emissions that resulted from human activities at the Brazilian Antarctic Scientific Station "Comandante Ferraz" (EACF) and collected emissions data relating to these activities from January to March 2011. The present work aims to identify the sources of GHG emissions, their characteristics, and composition, using as methodology and framework basis the international ISO 14,064:07 and the GHG Protocol. We addressed emissions of CO(2), CH(4), and N(2)O arising from the use of vehicles, diesel-electric generators, boilers, and wastewater treatment for the sewage treatment plant. We identified that the main GHG emissions derived from the activities of power generation using diesel and boilers (more than 80% of the emissions), adding more than 772 t of CO(2) equivalents. We identified that the diesel generators and boilers are the most important sources of emission by Expedition XXIX (2010-2011). In that CO(2) is principally emitted in relation to electrical energy generation from diesel generators, we emphasize the need for fuel burning reduction through energy consumption reduction. Copyright © 2012 Wiley Periodicals, Inc.

  15. Freeze concentration of proteins in Antarctic krill wash water

    Science.gov (United States)

    Qi, Xiangming; Xu, Jing; Zhao, Kuo; Guo, Hui; Ma, Lei

    2017-12-01

    Water-washing removes fluoride from Antarctic krill but produces large volumes of wash water containing water- soluble proteins and fluoride. The freeze concentration method was tested to determine if it could be used to recover water-soluble proteins while leaving the fluoride in solution. After freezing and thawing the wash water, protein and fluoride contents of the thawed fractions were determined to explore the melting regularity of components in the wash water. The highest concentration factors of protein and fluoride were obtained after 80 min of thawing, such as 1.48 ± 0.06 and 1.35 ± 0.04 times, respectively. The free amino-nitrogen (FAN) content and sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern results revealed that the highest concentrations of all ingredients were obtained after 80 min of the process. The degree of hydrolysis of all fractions from the thawing process fluctuated in a narrow range around 12% during the entire process, indicating that the thawing order did not change with various proteins or time during the entire thawing course. These results demonstrate that the freeze concentration method can be used to concentrate protein solutions, even those with fluoride. It was concluded that condensation was achieved and no ingredient could be separated, regardless of fluoride, amino acids, or different proteins in the water.

  16. Bayesian Inversion for Large Scale Antarctic Ice Sheet Flow

    KAUST Repository

    Ghattas, Omar

    2015-01-07

    The flow of ice from the interior of polar ice sheets is the primary contributor to projected sea level rise. One of the main difficulties faced in modeling ice sheet flow is the uncertain spatially-varying Robin boundary condition that describes the resistance to sliding at the base of the ice. Satellite observations of the surface ice flow velocity, along with a model of ice as a creeping incompressible shear-thinning fluid, can be used to infer this uncertain basal boundary condition. We cast this ill-posed inverse problem in the framework of Bayesian inference, which allows us to infer not only the basal sliding parameters, but also the associated uncertainty. To overcome the prohibitive nature of Bayesian methods for large-scale inverse problems, we exploit the fact that, despite the large size of observational data, they typically provide only sparse information on model parameters. We show results for Bayesian inversion of the basal sliding parameter field for the full Antarctic continent, and demonstrate that the work required to solve the inverse problem, measured in number of forward (and adjoint) ice sheet model solves, is independent of the parameter and data dimensions

  17. Modeling Antarctic subglacial lake filling and drainage cycles

    Science.gov (United States)

    Dow, Christine F.; Werder, Mauro A.; Nowicki, Sophie; Walker, Ryan T.

    2016-07-01

    The growth and drainage of active subglacial lakes in Antarctica has previously been inferred from analysis of ice surface altimetry data. We use a subglacial hydrology model applied to a synthetic Antarctic ice stream to examine internal controls on the filling and drainage of subglacial lakes. Our model outputs suggest that the highly constricted subglacial environment of our idealized ice stream, combined with relatively high rates of water flow funneled from a large catchment, can combine to create a system exhibiting slow-moving pressure waves. Over a period of years, the accumulation of water in the ice stream onset region results in a buildup of pressure creating temporary channels, which then evacuate the excess water. This increased flux of water beneath the ice stream drives lake growth. As the water body builds up, it steepens the hydraulic gradient out of the overdeepened lake basin and allows greater flux. Eventually this flux is large enough to melt channels that cause the lake to drain. Lake drainage also depends on the internal hydrological development in the wider system and therefore does not directly correspond to a particular water volume or depth. This creates a highly temporally and spatially variable system, which is of interest for assessing the importance of subglacial lakes in ice stream hydrology and dynamics.

  18. Extracellular protease from the antarctic yeast Candida humicola.

    Science.gov (United States)

    Ray, M K; Devi, K U; Kumar, G S; Shivaji, S

    1992-06-01

    The psychrotrophic, dimorphic yeast Candida humicola, isolated from Antarctic soil, secretes an acidic protease into the medium. The secretion of this protease by C. humicola was found to be dependent on the composition of the medium. In YPD or yeast nitrogen base medium containing either amino acids or ammonium sulfate as the nitrogen source, the activity of the protease in the medium was low (basal level). However, when yeast nitrogen base medium was depleted of amino acids or ammonium sulfate and supplemented with proteins, the activity of the enzyme increased. The secretion of the enzyme was greater during exponential growth at low temperatures than during growth at higher temperatures. The purified protease had a molecular mass of 36,000 Da and was inhibited by pepstatin, iodoacetamide, and sodium dodecyl sulfate. Despite the prevalent cold temperatures in Antarctica, this extracellular protease of the psychrotrophic yeast C. humicola was active at temperatures ranging from 0 to 45 degrees C, with an optimum activity at 37 degrees C.

  19. Monitoring trace elements in Antarctic penguin chicks from South Shetland Islands, Antarctica.

    Science.gov (United States)

    Jerez, Silvia; Motas, Miguel; Benzal, Jesús; Diaz, Julia; Barbosa, Andrés

    2013-04-15

    The concentration of human activities in the near-shore ecosystems from the northern Antarctic Peninsula area can cause an increasing bioavailability of pollutants for the vulnerable Antarctic biota. Penguin chicks can reflect this potential impact in the rookeries during the breeding season. They also can reflect biomagnification phenomena since they are on the top of the Antarctic food chain. The concentrations of Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Cd and Pb were measured by ICP-MS in samples of liver, kidney, muscle, bone, feather and stomach content of gentoo, chinstrap and Adélie penguin chicks (n=15 individuals) collected opportunistically in the Islands of King George and Deception (South Shetland Islands, Antarctica). The detected levels of some trace elements were not as low as it could be expected in the isolated Antarctic region. Penguin chicks can be useful indicators of trace elements abundance in the study areas. Carcasses of Antarctic penguin chicks were used to evaluate the bioavailability of trace elements in the Islands of King George and Deception. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Mercury accumulation in sediments and seabird feathers from the Antarctic Peninsula

    International Nuclear Information System (INIS)

    Calle, Paola; Alvarado, Omar; Monserrate, Lorena; Cevallos, Juan Manuel; Calle, Nastenka; Alava, Juan José

    2015-01-01

    Highlights: • We assessed mercury bioaccumulation in seabirds in the Antarctic Peninsula. • Levels of Hg were higher in gentoo penguins & brown skuas than chinstrap penguins. • Mercury BMF in the brown skua/penguins relationship was higher than 1. • Long-range environmental transport is the likely mercury route in Antarctic. - Abstract: In an effort to assess the impact of mercury in the Antarctic Peninsula, we conducted ecotoxicological research in this region during the summer of 2012 and 2013. The objectives were to assess: (a) mercury levels in sediment samples; (b) mercury accumulation in Antarctic seabird feathers: Catharacta lonnbergi (brown skua), Pygoscelis papua (gentoo penguin) and Pygoscelis antarctica (chinstrap penguin); and (c) biomagnification (BMF predator/prey) and biota sediment accumulation (BSAF skuas/sediment) factors. Mercury concentrations in sediment were relatively low. Mercury concentrations were significantly higher in brown skuas and gentoo penguins than in chinstrap penguins (2012), and significantly higher in brown skuas than in both penguins (2013). BMF indicated 2–7.5 times greater mercury levels in brown skuas than in penguins. BSAF values suggested an apparent temporal decrease of 18.2% of this ratio from 2012 to 2013. Long-range environmental transport is the likely route of entry of mercury into the Antarctic Peninsula