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Sample records for antarctic bacterium pseudoalteromonas

  1. Life in the cold: a proteomic study of cold-repressed proteins in the antarctic bacterium pseudoalteromonas haloplanktis TAC125.

    PubMed

    Piette, Florence; D'Amico, Salvino; Mazzucchelli, Gabriel; Danchin, Antoine; Leprince, Pierre; Feller, Georges

    2011-06-01

    The proteomes expressed at 4°C and 18°C by the psychrophilic Antarctic bacterium Pseudoalteromonas haloplanktis were compared using two-dimensional differential in-gel electrophoresis with special reference to proteins repressed by low temperatures. Remarkably, the major cold-repressed proteins, almost undetectable at 4°C, were heat shock proteins involved in folding assistance.

  2. Molecular characterization of a cryptic plasmid from the psychrotrophic antarctic bacterium Pseudoalteromonas sp. 643A.

    PubMed

    Cieśliński, Hubert; Werbowy, Katarzyna; Kur, Józef; Turkiewicz, Marianna

    2008-09-01

    We report the identification and nucleotide sequence analysis of pKW1, a plasmid of the psychrotrophic bacterium Pseudoalteromonas sp. 643A isolated from the stomach of Antarctic krill Euphasia superba. pKW1 consists of 4583 bp, has a G+C content of 43% and seven putative open reading frames (ORFs). The deduced amino acid sequence from ORF-1 shared significant similarity with the plasmid replicase protein of Psychrobacter cryohalolentis, strain K5. The DNA region immediately downstream of the ORF-1 showed some homology with the Rep-binding sequence of the theta-replicating ColE2-type plasmids. The ORF-3 amino acid sequence revealed amino acid sequence homology with the mobilization protein of Psychrobacter sp. PRwf-1 and Moraxella catarrhalis, with identities of 28% and 25%, respectively. The ORF-4 showed 46% amino acid sequence homology with the putative relaxase/mobilization nuclease MobA of Hafnia alvei and 44% homology with the putative mobilization protein A of Pasterulla multocida. The copy number of pKW1 in Pseudoalteromonas sp. 643A was estimated of 15 copies per chromosome.

  3. Influence of Growth Temperature on Lipid and Phosphate Contents of Surface Polysaccharides from the Antarctic Bacterium Pseudoalteromonas haloplanktis TAC 125

    PubMed Central

    Corsaro, M. Michela; Lanzetta, Rosa; Parrilli, Ermenegilda; Parrilli, Michelangelo; Tutino, M. Luisa; Ummarino, Salvatore

    2004-01-01

    The chemical structural variations induced by different growth temperatures in the lipooligosaccharide and exopolysaccharide components extracted from the Antarctic bacterium Pseudoalteromonas haloplanktis TAC 125 are described. The increase in phosphorylation with the increase in growth temperature seems to be general, because it happens not only for the lipooligosaccharide but also for the exopolysaccharide. Structural variations in the lipid components of lipid A also occur. In addition, free lipid A is found at both 25 and 4°C but not at 15°C, which is the optimal growth temperature, suggesting a incomplete biosynthesis of the lipooligosaccharide component under the first two temperature conditions. PMID:14679221

  4. Influence of growth temperature on lipid and phosphate contents of surface polysaccharides from the antarctic bacterium Pseudoalteromonas haloplanktis TAC 125.

    PubMed

    Corsaro, M Michela; Lanzetta, Rosa; Parrilli, Ermenegilda; Parrilli, Michelangelo; Tutino, M Luisa; Ummarino, Salvatore

    2004-01-01

    The chemical structural variations induced by different growth temperatures in the lipooligosaccharide and exopolysaccharide components extracted from the Antarctic bacterium Pseudoalteromonas haloplanktis TAC 125 are described. The increase in phosphorylation with the increase in growth temperature seems to be general, because it happens not only for the lipooligosaccharide but also for the exopolysaccharide. Structural variations in the lipid components of lipid A also occur. In addition, free lipid A is found at both 25 and 4 degrees C but not at 15 degrees C, which is the optimal growth temperature, suggesting a incomplete biosynthesis of the lipooligosaccharide component under the first two temperature conditions.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Engineered marine Antarctic bacterium Pseudoalteromonas haloplanktis TAC125: a promising micro-organism for the bioremediation of aromatic compounds.

    PubMed

    Papa, R; Parrilli, E; Sannia, G

    2009-01-01

    The recombinant Antarctic Pseudoalteromonas haloplanktis TAC125 (P. haloplanktis TAC/tou) expressing toluene-o-xylene monooxygenase (ToMO) can efficiently convert several aromatic compounds into their corresponding catechols in a broad range of temperature. When the genome of P. haloplanktis TAC125 was analysed in silico, the presence of a DNA sequence coding for a putative laccase-like protein was revealed. It is well known that bacterial laccases are able to oxidize dioxygenated aromatic compounds such as catechols. We analysed the catabolic features, conferred by recombinant ToMO activity and the endogenous laccase enzymatic activity, of P. haloplanktis TAC/tou engineered strain and its ability to grow on aromatic compounds as sole carbon and energy sources. Results presented highlight the broad potentiality of P. haloplanktis TAC/tou cells expressing recombinant ToMO in bioremediation and suggest the use of this engineered Antarctic bacterium in the bioremediation of chemically contaminated marine environments and/or cold effluents. This paper demonstrates the possibility to confer new and specific degradative capabilities to a bacterium isolated from an unpolluted environment (Antarctic seawater) transforming it into a bacterium able to grow on phenol as sole carbon and energy source.

  7. Large-scale biofilm cultivation of Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 for physiologic studies and drug discovery.

    PubMed

    Parrilli, Ermenegilda; Ricciardelli, Annarita; Casillo, Angela; Sannino, Filomena; Papa, Rosanna; Tilotta, Marco; Artini, Marco; Selan, Laura; Corsaro, Maria Michela; Tutino, Maria Luisa

    2016-03-01

    Microbial biofilms are mainly studied due to detrimental effects on human health but they are also well established in industrial biotechnology for the production of chemicals. Moreover, biofilm can be considered as a source of novel drugs since the conditions prevailing within biofilm can allow the production of specific metabolites. Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 when grown in biofilm condition produces an anti-biofilm molecule able to inhibit the biofilm of the opportunistic pathogen Staphylococcus epidermidis. In this paper we set up a P. haloplanktis TAC125 biofilm cultivation methodology in automatic bioreactor. The biofilm cultivation was designated to obtain two goals: (1) the scale up of cell-free supernatant production in an amount necessary for the anti-biofilm molecule/s purification; (2) the recovery of P. haloplanktis TAC125 cells grown in biofilm for physiological studies. We set up a fluidized-bed reactor fermentation in which floating polystyrene supports were homogeneously mixed, exposing an optimal air-liquid interface to let bacterium biofilm formation. The proposed methodology allowed a large-scale production of anti-biofilm molecule and paved the way to study differences between P. haloplanktis TAC125 cells grown in biofilm and in planktonic conditions. In particular, the modifications occurring in the lipopolysaccharide of cells grown in biofilm were investigated.

  8. Recombinant expression of Toluene o-Xylene Monooxygenase (ToMO) from Pseudomonas stutzeri OX1 in the marine Antarctic bacterium Pseudoalteromonas haloplanktis TAC125.

    PubMed

    Siani, Loredana; Papa, Rosanna; Di Donato, Alberto; Sannia, Giovanni

    2006-11-10

    The psychrophilic bacterium Pseudoalteromonas haloplanktis TAC125, isolated from Antarctic seawater, was used as recipient for a biodegradative gene of the mesophilic Pseudomonas stutzeri OX1. tou cluster, coding for Toluene o-Xylene Monooxygenase (ToMO), was successfully cloned and expressed into a "cold expression" vector. Apparent catalytic parameters of the recombinant microorganisms on three different substrates were determined and compared with those exhibited by Escherichia coli recombinant cells expressing ToMO. Production of a catalytically efficient TAC/tou microorganism supports the possibility of developing specific degradative capabilities for the bioremediation of chemically contaminated marine environments and of industrial effluents characterised by low temperatures.

  9. Ligand-rebinding kinetics of 2/2 hemoglobin from the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125.

    PubMed

    Russo, Roberta; Giordano, Daniela; di Prisco, Guido; Hui Bon Hoa, Gaston; Marden, Michael C; Verde, Cinzia; Kiger, Laurent

    2013-09-01

    Kinetic studies were performed on ligand rebinding to a cold-adapted globin of the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 (Ph-2/2HbO). This 2/2 hemoglobin displays a rapid spectroscopic phase that is independent of CO concentration, followed by the standard bimolecular recombination. While the geminate recombination usually occurs on a ns timescale, Ph-2/2HbO displays a component of about 1μs that accounts for half of the geminate phase at 8°C, indicative of a relatively slow internal ligand binding. The O2 binding kinetics were measured in competition with CO to allow a short-time exposure of the deoxy hemes to O2 before CO replacement. Indeed Ph-2/2HbO is readily oxidised in the presence of O2, probably due to a superoxide character of the FeO2 bond induced by of a hydrogen-bond donor amino-acid residue. Upon O2 release or iron oxidation a distal residue (probably Tyr) is able to reversibly bind to the heme and as such to compete for binding with an external ligand. The transient hexacoordinated ferrous His-Fe-Tyr conformation after O2 dissociation could initiate the electron transfer from the iron toward its final acceptor, molecular O2 under our conditions. The hexacoordination via the distal Tyr is only partial, indicating a weak interaction between Tyr and the heme under atmospheric pressure. Hydrostatic high pressure enhances the hexacoordination indicating a flexible globin that allows structural changes. The O2 binding affinity for Ph-2/2HbO, poorly affected by the competition with Tyr, is about 1Torr at 8°C, pH7.0, which is compatible for an in vivo O2 binding function; however, this globin is more likely involved in a redox reaction associating diatomic ligands and their derived oxidative species. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.

  10. Structural flexibility of the heme cavity in the cold-adapted truncated hemoglobin from the Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125.

    PubMed

    Giordano, Daniela; Pesce, Alessandra; Boechi, Leonardo; Bustamante, Juan Pablo; Caldelli, Elena; Howes, Barry D; Riccio, Alessia; di Prisco, Guido; Nardini, Marco; Estrin, Dario; Smulevich, Giulietta; Bolognesi, Martino; Verde, Cinzia

    2015-08-01

    Truncated hemoglobins build one of the three branches of the globin protein superfamily. They display a characteristic two-on-two α-helical sandwich fold and are clustered into three groups (I, II and III) based on distinct structural features. Truncated hemoglobins are present in eubacteria, cyanobacteria, protozoa and plants. Here we present a structural, spectroscopic and molecular dynamics characterization of a group-II truncated hemoglobin, encoded by the PSHAa0030 gene from Pseudoalteromonas haloplanktis TAC125 (Ph-2/2HbO), a cold-adapted Antarctic marine bacterium hosting one flavohemoglobin and three distinct truncated hemoglobins. The Ph-2/2HbO aquo-met crystal structure (at 2.21 Å resolution) shows typical features of group-II truncated hemoglobins, namely the two-on-two α-helical sandwich fold, a helix Φ preceding the proximal helix F, and a heme distal-site hydrogen-bonded network that includes water molecules and several distal-site residues, including His(58)CD1. Analysis of Ph-2/2HbO by electron paramagnetic resonance, resonance Raman and electronic absorption spectra, under varied solution conditions, shows that Ph-2/2HbO can access diverse heme ligation states. Among these, detection of a low-spin heme hexa-coordinated species suggests that residue Tyr(42)B10 can undergo large conformational changes in order to act as the sixth heme-Fe ligand. Altogether, the results show that Ph-2/2HbO maintains the general structural features of group-II truncated hemoglobins but displays enhanced conformational flexibility in the proximity of the heme cavity, a property probably related to the functional challenges, such as low temperature, high O2 concentration and low kinetic energy of molecules, experienced by organisms living in the Antarctic environment.

  11. Cloning, expression and biochemical characterization of recombinant superoxide dismutase from Antarctic psychrophilic bacterium Pseudoalteromonas sp. ANT506.

    PubMed

    Wang, Quan-Fu; Wang, Yi-Fan; Hou, Yan-Hua; Shi, Yong-Lei; Han, Han; Miao, Miao; Wu, Ying-Ying; Liu, Yuan-Ping; Yue, Xiao-Na; Li, Yu-Jin

    2016-07-01

    In this study, a superoxide dismutase gene (PsSOD) from Pseudoalteromonas sp. ANT506 was cloned and over expressed in Escherichia coli. The PsSOD has an open reading frame of 582 bp with a putative product of 193 amino acid residue and an estimated molecular size of 21.4 kDa. His-tagged PsSOD was subsequently purified 12.6-fold by Ni-affinity chromatography and the yield of 22.9%. The characterization of the purified rPsSOD exhibited maximum activity at 30 °C and pH 8.0. The enzyme exhibited 13.9% activity at 0 °C and had high-thermo lability at higher than 50 °C. rPsSOD exhibited well capability to 2.5 M NaCl (62.4%). These results indicated that rPsSOD exhibited special catalytic properties.

  12. Development of a genetic system for the deep-sea psychrophilic bacterium Pseudoalteromonas sp. SM9913

    PubMed Central

    2014-01-01

    Background Pseudoalteromonas species are a group of marine gammaproteobacteria frequently found in deep-sea sediments, which may play important roles in deep-sea sediment ecosystem. Although genome sequence analysis of Pseudoalteromonas has revealed some specific features associated with adaptation to the extreme deep-sea environment, it is still difficult to study how Pseudoalteromonas adapt to the deep-sea environment due to the lack of a genetic manipulation system. The aim of this study is to develop a genetic system in the deep-sea sedimentary bacterium Pseudoalteromonas sp. SM9913, making it possible to perform gene mutation by homologous recombination. Results The sensitivity of Pseudoalteromonas sp. SM9913 to antibiotic was investigated and the erythromycin resistance gene was chosen as the selective marker. A shuttle vector pOriT-4Em was constructed and transferred into Pseudoalteromonas sp. SM9913 through intergeneric conjugation with an efficiency of 1.8 × 10-3, which is high enough to perform the gene knockout assay. A suicide vector pMT was constructed using pOriT-4Em as the bone vector and sacB gene as the counterselective marker. The epsT gene encoding the UDP-glucose lipid carrier transferase was selected as the target gene for inactivation by in-frame deletion. The epsT was in-frame deleted using a two-step integration–segregation strategy after transferring the suicide vector pMT into Pseudoalteromonas sp. SM9913. The ΔepsT mutant showed approximately 73% decrease in the yield of exopolysaccharides, indicating that epsT is an important gene involved in the EPS production of SM9913. Conclusions A conjugal transfer system was constructed in Pseudoalteromonas sp. SM9913 with a wide temperature range for selection and a high transfer efficiency, which will lay the foundation of genetic manipulation in this strain. The epsT gene of SM9913 was successfully deleted with no selective marker left in the chromosome of the host, which thus make it

  13. Structural investigation and biological activity of the lipooligosaccharide from the psychrophilic bacterium Pseudoalteromonas haloplanktis TAB 23.

    PubMed

    Carillo, Sara; Pieretti, Giuseppina; Parrilli, Ermenegilda; Tutino, Maria L; Gemma, Sabrina; Molteni, Monica; Lanzetta, Rosa; Parrilli, Michelangelo; Corsaro, Maria M

    2011-06-14

    Pseudoalteromonas haloplanktis TAB 23 is a Gram-negative psychrophilic bacterium isolated from the Antarctic coastal sea. To survive in these conditions psychrophilic bacteria have evolved typical membrane lipids and "antifreeze" proteins to protect the inner side of the microorganism. As for Gram-negative bacteria, the outer membrane is mainly constituted by lipopoly- or lipooligosaccharides (LPS or LOS, respectively), which lean towards the external environment. Despite this, very little is known about the peculiarity of LPS from Gram-negative psychrophilic bacteria and what their role is in adaptation to cold temperature. Here we report the complete structure of the LOS from P. haloplanktis TAB 23. The lipid A was characterized by MALDI-TOF MS analysis and was tested in vitro showing a significant inhibitory effect on the LPS-induced pro-inflammatory cytokine production when added in culture with LPS from Escherichia coli. The product obtained after de-O-acylation of the LPS was analyzed by MALDI-TOF MS revealing the presence of several molecular species, differing in phosphorylation degree and oligosaccharide length. The oligosaccharide portion released after strong alkaline hydrolysis was purified by anion-exchange chromatography-pulsed amperometric detection (HPAEC-PAD) to give three main fractions, characterized by means of 2D NMR spectroscopy, which showed a very short highly phosphorylated saccharidic chain with the following general structure. α-Hepp3R,6R,4R'-(1→5)-α-Kdop4P-(2→6)-β-GlcpN4R-(1→6)-α-GlcpN1P (R=-H(2)PO(3) or -H; R'=α-Galp-(1→4)-β-Galp-(1→ or H-). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. The Haloprotease CPI Produced by the Moderately Halophilic Bacterium Pseudoalteromonas ruthenica Is Secreted by the Type II Secretion Pathway▿ †

    PubMed Central

    Sánchez-Porro, Cristina; Mellado, Encarnación; Pugsley, Anthony P.; Francetic, Olivera; Ventosa, Antonio

    2009-01-01

    The gene (cpo) encoding the extracellular protease CPI produced by the moderately halophilic bacterium Pseudoalteromonas ruthenica CP76 was cloned, and its nucleotide sequence was analyzed. The cpo gene encodes a 733-residue protein showing sequence similarity to metalloproteases of the M4 family. The type II secretion apparatus was shown to be responsible for secretion of the haloprotease CPI. PMID:19376897

  15. Inhibition of algal spore germination by the marine bacterium Pseudoalteromonas tunicata.

    PubMed

    Egan, S; James, S; Holmström, C; Kjelleberg, S

    2001-03-01

    A collection of 56 bacteria isolated from different surfaces in the marine environment were assayed for their effects on the germination of spores from the common green alga Ulva lactuca. Thirteen bacterial isolates were shown to inhibit spore germination. Of these bacteria, Pseudoalteromonas tunicata displayed the most pronounced effects against algal spores. Further characterisation of the anti-algal activity of P. tunicata was performed and it was found that this bacterium produces an extracellular component with specific activity toward algal spores that is heat-sensitive, polar and between 3 and 10 kDa in size. This biologically active compound was also found to prevent the germination of spores from the red alga Polysiphonia sp. and, given the widespread occurrence of P. tunicata in a range of marine habitats, this may suggest that it is effective against a variety of marine algae.

  16. Discovery of a novel iota carrageenan sulfatase isolated from the marine bacterium Pseudoalteromonas carrageenovora

    NASA Astrophysics Data System (ADS)

    Genicot, Sabine; Groisillier, Agnès; Rogniaux, Hélène; Meslet-Cladière, Laurence; Barbeyron, Tristan; Helbert, William

    2014-08-01

    Carrageenans are sulfated polysaccharides extracted from the cell wall of some marine red algae. These polysaccharides are widely used as gelling, stabilizing, and viscosifying agents in the food and pharmaceutical industries. Since the rheological properties of these polysaccharides depend on their sulfate content, we screened several isolated marine bacteria for carrageenan specific sulfatase activity, in the aim of developing enzymatic bioconversion of carrageenans. As a result of the screening, an iota-carrageenan sulfatase was detected in the cell-free lysate of the marine bacterium Pseudoalteromonas carrageenovora strain PscT. It was purified through Phenyl Sepharose and Diethylaminoethyl Sepharose chromatography. The pure enzyme, Psc ?-CgsA, was characterized. It had a molecular weight of 115.9 kDaltons and exhibited an optimal activity/stability at pH ~8.3 and at 40°C ± 5°C. It was inactivated by phenylmethylsulfonyl fluoride but not by ethylene diamine tetraacetic acid. Psc ?-CgsA specifically catalyzes the hydrolysis of the 4-S sulfate of iota-carrageenan. The purified enzyme could transform iota-carrageenan into hybrid iota-/alpha- or pure alpha-carrageenan under controlled conditions. The gene encoding Psc ?-CgsA, a protein of 1038 amino acids, was cloned into Escherichia coli, and the sequence analysis revealed that Psc ?-CgsA has more than 90% sequence identity with a putative uncharacterized protein Q3IKL4 from the marine strain Pseudoalteromonas haloplanktis TAC 125, but besides this did not share any homology to characterized sulfatases. Phylogenetic studies show that P. carrageenovora sulfatase thus represents the first characterized member of a new sulfatase family, with a C-terminal domain having strong similarity with the superfamily of amidohydrolases, highlighting the still unexplored diversity of marine polysaccharide modifying enzymes.

  17. Discovery of a novel iota carrageenan sulfatase isolated from the marine bacterium Pseudoalteromonas carrageenovora

    PubMed Central

    Genicot, Sabine M.; Groisillier, Agnès; Rogniaux, Hélène; Meslet-Cladière, Laurence; Barbeyron, Tristan; Helbert, William

    2014-01-01

    Carrageenans are sulfated polysaccharides extracted from the cell wall of some marine red algae. These polysaccharides are widely used as gelling, stabilizing, and viscosifying agents in the food and pharmaceutical industries. Since the rheological properties of these polysaccharides depend on their sulfate content, we screened several isolated marine bacteria for carrageenan specific sulfatase activity, in the aim of developing enzymatic bioconversion of carrageenans. As a result of the screening, an iota-carrageenan sulfatase was detected in the cell-free lysate of the marine bacterium Pseudoalteromonas carrageenovora strain PscT. It was purified through Phenyl Sepharose and Diethylaminoethyl Sepharose chromatography. The pure enzyme, Psc ι-CgsA, was characterized. It had a molecular weight of 115.9 kDaltons and exhibited an optimal activity/stability at pH ~8.3 and at 40 ± 5°C. It was inactivated by phenylmethylsulfonyl fluoride but not by ethylene diamine tetraacetic acid. Psc ι-CgsA specifically catalyzes the hydrolysis of the 4-S sulfate of iota-carrageenan. The purified enzyme could transform iota-carrageenan into hybrid iota-/alpha- or pure alpha-carrageenan under controlled conditions. The gene encoding Psc ι-CgsA, a protein of 1038 amino acids, was cloned into Escherichia coli, and the sequence analysis revealed that Psc ι-CgsA has more than 90% sequence identity with a putative uncharacterized protein Q3IKL4 from the marine strain Pseudoalteromonas haloplanktis TAC 125, but besides this did not share any homology to characterized sulfatases. Phylogenetic studies show that P. carrageenovora sulfatase thus represents the first characterized member of a new sulfatase family, with a C-terminal domain having strong similarity with the superfamily of amidohydrolases, highlighting the still unexplored diversity of marine polysaccharide modifying enzymes. PMID:25207269

  18. Draft Genome Sequence of Pseudoalteromonas tetraodonis Strain MQS005, a Bacterium with Potential Quorum-Sensing Regulation

    PubMed Central

    Pan, Yonglong; Wang, Yanbo; Yan, Xiaoqing; Mazumder, Asit

    2016-01-01

    We present here the draft genome sequence of Pseudoalteromonas tetraodonis strain MQS005, a bacterium possessing potential quorum-sensing regulatory activity. This strain was isolated from water from the South China Sea, People’s Republic of China. The assembly consists of 4,252,538 bp and contains 144 contigs, with a G+C content of 41.85%. PMID:27491986

  19. Exopolysaccharides Play a Role in the Swarming of the Benthic Bacterium Pseudoalteromonas sp. SM9913

    PubMed Central

    Liu, Ang; Mi, Zi-Hao; Zheng, Xiao-Yu; Yu, Yang; Su, Hai-Nan; Chen, Xiu-Lan; Xie, Bin-Bin; Zhou, Bai-Cheng; Zhang, Yu-Zhong; Qin, Qi-Long

    2016-01-01

    Most marine bacteria secrete exopolysaccharide (EPS), which is important for bacterial survival in the marine environment. However, it is still unclear whether the self-secreted EPS is involved in marine bacterial motility. Here we studied the role of EPS in the lateral flagella-driven swarming motility of benthic bacterium Pseudoalteromonas sp. SM9913 (SM9913) by a comparison of wild SM9913 and ΔepsT, an EPS synthesis defective mutant. Reduction of EPS production in ΔepsT did not affect the growth rate or the swimming motility, but significantly decreased the swarming motility on a swarming plate, suggesting that the EPS may play a role in SM9913 swarming. However, the expression and assembly of lateral flagella in ΔepsT were not affected. Instead, ΔepsT had a different swarming behavior from wild SM9913. The swarming of ΔepsT did not have an obvious rapid swarming period, and its rate became much lower than that of wild SM9913 after 35 h incubation. An addition of surfactin or SM9913 EPS on the surface of the swarming plate could rescue the swarming level. These results indicate that the self-secreted EPS is required for the swarming of SM9913. This study widens our understanding of the function of the EPS of benthic bacteria. PMID:27092127

  20. Biofilm Development and Cell Death in the Marine Bacterium Pseudoalteromonas tunicata

    PubMed Central

    Mai-Prochnow, Anne; Evans, Flavia; Dalisay-Saludes, Doralyn; Stelzer, Sacha; Egan, Suhelen; James, Sally; Webb, Jeremy S.; Kjelleberg, Staffan

    2004-01-01

    The newly described green-pigmented bacterium Pseudoalteromonas tunicata (D2) produces target-specific inhibitory compounds against bacteria, algae, fungi, and invertebrate larvae and is frequently found in association with living surfaces in the marine environment. As part of our studies on the ecology of P. tunicata and its interaction with marine surfaces, we examined the ability of P. tunicata to form biofilms under continuous culture conditions within the laboratory. P. tunicata biofilms exhibited a characteristic architecture consisting of differentiated microcolonies surrounded by water channels. Remarkably, we observed a repeatable pattern of cell death during biofilm development of P. tunicata, similar to that recently reported for biofilms of Pseudomonas aeruginosa (J. S. Webb et al., J. Bacteriol. 185:4585-4595, 2003). Killing and lysis occurred inside microcolonies, apparently resulting in the formation of voids within these structures. A subpopulation of viable cells was always observed within the regions of killing in the biofilm. Moreover, extensive killing in mature biofilms appeared to result in detachment of the biofilm from the substratum. A novel 190-kDa autotoxic protein produced by P. tunicata, designated AlpP, was found to be involved in this biofilm killing and detachment. A ΔalpP mutant derivative of P. tunicata was generated, and this mutant did not show cell death during biofilm development. We propose that AlpP-mediated cell death plays an important role in the multicellular biofilm development of P. tunicata and subsequent dispersal of surviving cells within the marine environment. PMID:15184116

  1. Biofilm development and cell death in the marine bacterium Pseudoalteromonas tunicata.

    PubMed

    Mai-Prochnow, Anne; Evans, Flavia; Dalisay-Saludes, Doralyn; Stelzer, Sacha; Egan, Suhelen; James, Sally; Webb, Jeremy S; Kjelleberg, Staffan

    2004-06-01

    The newly described green-pigmented bacterium Pseudoalteromonas tunicata (D2) produces target-specific inhibitory compounds against bacteria, algae, fungi, and invertebrate larvae and is frequently found in association with living surfaces in the marine environment. As part of our studies on the ecology of P. tunicata and its interaction with marine surfaces, we examined the ability of P. tunicata to form biofilms under continuous culture conditions within the laboratory. P. tunicata biofilms exhibited a characteristic architecture consisting of differentiated microcolonies surrounded by water channels. Remarkably, we observed a repeatable pattern of cell death during biofilm development of P. tunicata, similar to that recently reported for biofilms of Pseudomonas aeruginosa (J. S. Webb et al., J. Bacteriol. 185:4585-4595, 2003). Killing and lysis occurred inside microcolonies, apparently resulting in the formation of voids within these structures. A subpopulation of viable cells was always observed within the regions of killing in the biofilm. Moreover, extensive killing in mature biofilms appeared to result in detachment of the biofilm from the substratum. A novel 190-kDa autotoxic protein produced by P. tunicata, designated AlpP, was found to be involved in this biofilm killing and detachment. A Delta alpP mutant derivative of P. tunicata was generated, and this mutant did not show cell death during biofilm development. We propose that AlpP-mediated cell death plays an important role in the multicellular biofilm development of P. tunicata and subsequent dispersal of surviving cells within the marine environment.

  2. Involvement of an Extracellular Protease in Algicidal Activity of the Marine Bacterium Pseudoalteromonas sp. Strain A28

    PubMed Central

    Lee, Sun-og; Kato, Junichi; Takiguchi, Noboru; Kuroda, Akio; Ikeda, Tsukasa; Mitsutani, Atsushi; Ohtake, Hisao

    2000-01-01

    The marine bacterium Pseudoalteromonas sp. strain A28 was able to kill the diatom Skeletonema costatum strain NIES-324. The culture supernatant of strain A28 showed potent algicidal activity when it was applied to a paper disk placed on a lawn of S. costatum NIES-324. The condensed supernatant, which was prepared by subjecting the A28 culture supernatant to ultrafiltration with a 10,000-Mw-cutoff membrane, showed algicidal activity, suggesting that strain A28 produced extracellular substances capable of killing S. costatum cells. The condensed supernatant was then found to have protease and DNase activities. Two Pseudoalteromonas mutants lacking algicidal activity, designated NH1 and NH2, were selected after N-methyl-N′-nitrosoguanidine mutagenesis. The culture supernatants of NH1 and NH2 showed less than 15% of the protease activity detected with the parental strain, A28. The protease was purified to homogeneity from A28 culture supernatants by using ion-exchange chromatography followed by preparative gel electrophoresis. Paper-disk assays revealed that the purified protease had potent algicidal activity. The purified protease had a molecular mass for 50 kDa, and the N-terminal amino acid sequence was determined to be Ala-Thr-Pro-Asn-Asp-Pro. The optimum pH and temperature of the protease were found to be 8.8 and 30°C, respectively, by using succinyl-Ala-Ala-Pro-Phe-p-nitroanilide as a substrate. The protease activity was strongly inhibited by phenylmethylsulfonyl fluoride, diisopropyl fluorophosphate, antipain, chymostatin, and leupeptin. No significant inhibition was detected with EDTA, EGTA, phenanthroline or tetraethylenepentamine. These results suggest that Pseudoalteromonas sp. strain A28 produced an extracellular serine protease which was responsible for the algicidal activity of this marine bacterium. PMID:11010878

  3. Proteomic studies highlight outer-membrane proteins related to biofilm development in the marine bacterium Pseudoalteromonas sp. D41.

    PubMed

    Ritter, Andrés; Com, Emmanuelle; Bazire, Alexis; Goncalves, Marina Dos Santos; Delage, Ludovic; Le Pennec, Gaël; Pineau, Charles; Dreanno, Catherine; Compère, Chantal; Dufour, Alain

    2012-11-01

    Bacterial biofilm development is conditioned by complex processes involving bacterial attachment to surfaces, growth, mobility, and exoproduct production. The marine bacterium Pseudoalteromonas sp. strain D41 is able to attach strongly onto a wide variety of substrates, which promotes subsequent biofilm development. Study of the outer-membrane and total soluble proteomes showed ten spots with significant intensity variations when this bacterium was grown in biofilm compared to planktonic cultures. MS/MS de novo sequencing analysis allowed the identification of four outer-membrane proteins of particular interest since they were strongly induced in biofilms. These proteins are homologous to a TonB-dependent receptor (TBDR), to the OmpW and OmpA porins, and to a type IV pilus biogenesis protein (PilF). Gene expression assays by quantitative RT-PCR showed that the four corresponding genes were upregulated during biofilm development on hydrophobic and hydrophilic surfaces. The Pseudomonas aeruginosa mutants unable to produce any of the OmpW, OmpA, and PilF homologues yielded biofilms with lower biovolumes and altered architectures, confirming the involvement of these proteins in the biofilm formation process. Our results indicate that Pseudoalteromonas sp. D41 shares biofilm formation mechanisms with human pathogenic bacteria, but also relies on TBDR, which might be more specific to the marine environment. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Stereochemical course of hydrolytic reaction catalyzed by alpha-galactosidase from cold adaptable marine bacterium of genus Pseudoalteromonas

    NASA Astrophysics Data System (ADS)

    Bakunina, Irina; Balabanova, Larissa; Golotin, Vasiliy; Slepchenko, Lyubov; Isakov, Vladimir; Rasskazov, Valeriy

    2014-10-01

    The recombinant α-galactosidase of the marine bacterium (α-PsGal) was synthesized with the use of the plasmid 40Gal, consisting of plasmid pET-40b (+) (Novagen) and the gene corresponding to the open reading frame of the mature α-galactosidase of marine bacterium Pseudoalteromonas sp. KMM 701, transformed into the E. coli Rosetta(DE3) cells. In order to understand the mechanism of action, the stereochemistry of hydrolysis of 4-nitrophenyl α-D-galactopyranoside (4-NPGP) by α-PsGal was measured by 1H NMR spectroscopy. The kinetics of formation of α- and β-anomer of galactose showed that α-anomer initially formed and accumulated, and then an appreciable amount of β-anomer appeared as a result of mutarotation. The data clearly show that the enzymatic hydrolysis of 4-NPGP proceeds with the retention of anomeric configuration, probably, due to a double displacement mechanism of reaction.

  5. Draft Genome Sequence of Pseudoalteromonas sp. Strain PLSV, an Ulvan-Degrading Bacterium

    PubMed Central

    Kopel, Moran; Helbert, William; Henrissat, Bernard; Doniger, Tirza

    2014-01-01

    We present the draft genome sequence of Pseudoalteromonas sp. strain PLSV, isolated from the feces of an Aplysia sea slug. The addition of the PLSV genome to the existing genomes of three other ulvan-degrading bacterial species will enhance our understanding of ulvan utilization. PMID:25502665

  6. Complete Genome Sequence of Pseudoalteromonas piscicida Strain DE2-B, a Bacterium with Broad Inhibitory Activity toward Human and Fish Pathogens

    PubMed Central

    Needleman, David S.; Watson, Michael A.

    2017-01-01

    ABSTRACT Pseudoalteromonas piscicida strain DE2-B is a halophilic bacterium which has broad inhibitory activity toward vibrios and other human and fish pathogens. We report the first closed genome sequence for this species, which consists of two chromosomes (4,128,210 and 1,188,838 bp). Annotation revealed multiple genes encoding proteases with potential antibacterial properties. PMID:28818891

  7. Complete genome sequence of a marine bacterium with two chromosomes, Pseudoalteromonas translucida KMM 520(T).

    PubMed

    Rong, Jin-Cheng; Liu, Min; Li, Yi; Sun, Tian-Yong; Pang, Xiu-Hua; Qin, Qi-Long; Chen, Xiu-Lan; Xie, Bin-Bin

    2016-04-01

    Bacteria with multiple chromosomes provide new insights into the evolution of multipartite genome structures and bacterial survival strategies. In this study, we report the complete genome sequence of Pseudoalteromonas translucida KMM 520(T), which contains two circular chromosomes and comprises 4,147,593 bp with a mean G+C content of 40.1%. The two chromosomes have similar G+C contents and similar percentages of coding regions. Chromosome II of P. translucida possesses a plasmid-type replication initiator protein (RepA), which indicated that chromosome II is probably originated from a plasmid. COG functional categories revealed that the two chromosomes have divergent distributions of functional categories, which indicated that they bear different responsibilities for cellular functions. The complete genome sequence of P. translucida contributes to a better understanding of the origin and evolution of the additional chromosome and the physiology of Pseudoalteromonas genus. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Antibiofilm Activity of the Marine Bacterium Pseudoalteromonas sp. Strain 3J6▿

    PubMed Central

    Dheilly, Alexandra; Soum-Soutéra, Emmanuelle; Klein, Géraldine L.; Bazire, Alexis; Compère, Chantal; Haras, Dominique; Dufour, Alain

    2010-01-01

    Biofilm formation results in medical threats or economic losses and is therefore a major concern in a variety of domains. In two-species biofilms of marine bacteria grown under dynamic conditions, Pseudoalteromonas sp. strain 3J6 formed mixed biofilms with Bacillus sp. strain 4J6 but was largely predominant over Paracoccus sp. strain 4M6 and Vibrio sp. strain D01. The supernatant of Pseudoalteromonas sp. 3J6 liquid culture (SN3J6) was devoid of antibacterial activity against free-living Paracoccus sp. 4M6 and Vibrio sp. D01 cells, but it impaired their ability to grow as single-species biofilms and led to higher percentages of nonviable cells in 48-h biofilms. Antibiofilm molecules of SN3J6 were able to coat the glass surfaces used to grow biofilms and reduced bacterial attachment about 2-fold, which might partly explain the biofilm formation defect but not the loss of cell viability. SN3J6 had a wide spectrum of activity since it affected all Gram-negative marine strains tested except other Pseudoalteromonas strains. Biofilm biovolumes of the sensitive strains were reduced 3- to 530-fold, and the percentages of nonviable cells were increased 3- to 225-fold. Interestingly, SN3J6 also impaired biofilm formation by three strains belonging to the human-pathogenic species Pseudomonas aeruginosa, Salmonella enterica, and Escherichia coli. Such an antibiofilm activity is original and opens up a variety of applications for Pseudoalteromonas sp. 3J6 and/or its active exoproducts in biofilm prevention strategies. PMID:20363799

  9. Antibiofilm activity of the marine bacterium Pseudoalteromonas sp. strain 3J6.

    PubMed

    Dheilly, Alexandra; Soum-Soutéra, Emmanuelle; Klein, Géraldine L; Bazire, Alexis; Compère, Chantal; Haras, Dominique; Dufour, Alain

    2010-06-01

    Biofilm formation results in medical threats or economic losses and is therefore a major concern in a variety of domains. In two-species biofilms of marine bacteria grown under dynamic conditions, Pseudoalteromonas sp. strain 3J6 formed mixed biofilms with Bacillus sp. strain 4J6 but was largely predominant over Paracoccus sp. strain 4M6 and Vibrio sp. strain D01. The supernatant of Pseudoalteromonas sp. 3J6 liquid culture (SN(3J6)) was devoid of antibacterial activity against free-living Paracoccus sp. 4M6 and Vibrio sp. D01 cells, but it impaired their ability to grow as single-species biofilms and led to higher percentages of nonviable cells in 48-h biofilms. Antibiofilm molecules of SN(3J6) were able to coat the glass surfaces used to grow biofilms and reduced bacterial attachment about 2-fold, which might partly explain the biofilm formation defect but not the loss of cell viability. SN(3J6) had a wide spectrum of activity since it affected all Gram-negative marine strains tested except other Pseudoalteromonas strains. Biofilm biovolumes of the sensitive strains were reduced 3- to 530-fold, and the percentages of nonviable cells were increased 3- to 225-fold. Interestingly, SN(3J6) also impaired biofilm formation by three strains belonging to the human-pathogenic species Pseudomonas aeruginosa, Salmonella enterica, and Escherichia coli. Such an antibiofilm activity is original and opens up a variety of applications for Pseudoalteromonas sp. 3J6 and/or its active exoproducts in biofilm prevention strategies.

  10. Anti-Biofilm Activity of a Long-Chain Fatty Aldehyde from Antarctic Pseudoalteromonas haloplanktis TAC125 against Staphylococcus epidermidis Biofilm

    PubMed Central

    Casillo, Angela; Papa, Rosanna; Ricciardelli, Annarita; Sannino, Filomena; Ziaco, Marcello; Tilotta, Marco; Selan, Laura; Marino, Gennaro; Corsaro, Maria M.; Tutino, Maria L.; Artini, Marco; Parrilli, Ermenegilda

    2017-01-01

    Staphylococcus epidermidis is a harmless human skin colonizer responsible for ~20% of orthopedic device-related infections due to its capability to form biofilm. Nowadays there is an interest in the development of anti-biofilm molecules. Marine bacteria represent a still underexploited source of biodiversity able to synthesize a broad range of bioactive compounds, including anti-biofilm molecules. Previous results have demonstrated that the culture supernatant of Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125 impairs the formation of S. epidermidis biofilm. Further, evidence supports the hydrophobic nature of the active molecule, which has been suggested to act as a signal molecule. In this paper we describe an efficient activity-guided purification protocol which allowed us to purify this anti-biofilm molecule and structurally characterize it by NMR and mass spectrometry analyses. Our results demonstrate that the anti-biofilm molecule is pentadecanal, a long-chain fatty aldehyde, whose anti-S. epidermidis biofilm activity has been assessed using both static and dynamic biofilm assays. The specificity of its action on S. epidermidis biofilm has been demonstrated by testing chemical analogs of pentadecanal differing either in the length of the aliphatic chain or in their functional group properties. Further, indications of the mode of action of pentadecanal have been collected by studying the bioluminescence of a Vibrio harveyi reporter strain for the detection of autoinducer AI-2 like activities. The data collected suggest that pentadecanal acts as an AI-2 signal. Moreover, the aldehyde metabolic role and synthesis in the Antarctic source strain has been investigated. To the best of our knowledge, this is the first report on the identification of an anti-biofilm molecule form from cold-adapted bacteria and on the action of a long-chain fatty aldehyde acting as an anti-biofilm molecule against S. epidermidis. PMID:28280714

  11. Anti-Biofilm Activity of a Long-Chain Fatty Aldehyde from Antarctic Pseudoalteromonas haloplanktis TAC125 against Staphylococcus epidermidis Biofilm.

    PubMed

    Casillo, Angela; Papa, Rosanna; Ricciardelli, Annarita; Sannino, Filomena; Ziaco, Marcello; Tilotta, Marco; Selan, Laura; Marino, Gennaro; Corsaro, Maria M; Tutino, Maria L; Artini, Marco; Parrilli, Ermenegilda

    2017-01-01

    Staphylococcus epidermidis is a harmless human skin colonizer responsible for ~20% of orthopedic device-related infections due to its capability to form biofilm. Nowadays there is an interest in the development of anti-biofilm molecules. Marine bacteria represent a still underexploited source of biodiversity able to synthesize a broad range of bioactive compounds, including anti-biofilm molecules. Previous results have demonstrated that the culture supernatant of Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125 impairs the formation of S. epidermidis biofilm. Further, evidence supports the hydrophobic nature of the active molecule, which has been suggested to act as a signal molecule. In this paper we describe an efficient activity-guided purification protocol which allowed us to purify this anti-biofilm molecule and structurally characterize it by NMR and mass spectrometry analyses. Our results demonstrate that the anti-biofilm molecule is pentadecanal, a long-chain fatty aldehyde, whose anti-S. epidermidis biofilm activity has been assessed using both static and dynamic biofilm assays. The specificity of its action on S. epidermidis biofilm has been demonstrated by testing chemical analogs of pentadecanal differing either in the length of the aliphatic chain or in their functional group properties. Further, indications of the mode of action of pentadecanal have been collected by studying the bioluminescence of a Vibrio harveyi reporter strain for the detection of autoinducer AI-2 like activities. The data collected suggest that pentadecanal acts as an AI-2 signal. Moreover, the aldehyde metabolic role and synthesis in the Antarctic source strain has been investigated. To the best of our knowledge, this is the first report on the identification of an anti-biofilm molecule form from cold-adapted bacteria and on the action of a long-chain fatty aldehyde acting as an anti-biofilm molecule against S. epidermidis.

  12. Cytoplasmic and Periplasmic Proteomic Signatures of Exponentially Growing Cells of the Psychrophilic Bacterium Pseudoalteromonas haloplanktis TAC125 ▿ †

    PubMed Central

    Wilmes, Boris; Kock, Holger; Glagla, Susanne; Albrecht, Dirk; Voigt, Birgit; Markert, Stephanie; Gardebrecht, Antje; Bode, Rüdiger; Danchin, Antoine; Feller, Georges; Hecker, Michael; Schweder, Thomas

    2011-01-01

    The psychrophilic model bacterium Pseudoalteromonas haloplanktis is characterized by remarkably fast growth rates under low-temperature conditions in a range from 5°C to 20°C. In this study the proteome of cellular compartments, the cytoplasm and periplasm, of P. haloplanktis strain TAC125 was analyzed under exponential growth conditions at a permissive temperature of 16°C. By means of two-dimensional protein gel electrophoresis and mass spectrometry, a first inventory of the most abundant cytoplasmic and periplasmic proteins expressed in a peptone-supplemented minimal medium was established. By this approach major enzymes of the amino acid catabolism of this marine bacterium could be functionally deduced. The cytoplasmic proteome showed a predominance of amino acid degradation pathways and tricarboxylic acid (TCA) cycle enzymes but also the protein synthesis machinery. Furthermore, high levels of cold acclimation and oxidative stress proteins could be detected at this moderate growth temperature. The periplasmic proteome was characterized by a significant abundance of transporters, especially of highly expressed putative TonB-dependent receptors. This high capacity for protein synthesis, efficient amino acid utilization, and substrate transport may contribute to the fast growth rates of the copiotrophic bacterium P. haloplanktis in its natural environments. PMID:21183643

  13. Induction of larval metamorphosis of the coral Acropora millepora by tetrabromopyrrole isolated from a Pseudoalteromonas bacterium.

    PubMed

    Tebben, Jan; Tapiolas, Dianne M; Motti, Cherie A; Abrego, David; Negri, Andrew P; Blackall, Linda L; Steinberg, Peter D; Harder, Tilmann

    2011-04-29

    The induction of larval attachment and metamorphosis of benthic marine invertebrates is widely considered to rely on habitat specific cues. While microbial biofilms on marine hard substrates have received considerable attention as specific signals for a wide and phylogenetically diverse array of marine invertebrates, the presumed chemical settlement signals produced by the bacteria have to date not been characterized. Here we isolated and fully characterized the first chemical signal from bacteria that induced larval metamorphosis of acroporid coral larvae (Acropora millepora). The metamorphic cue was identified as tetrabromopyrrole (TBP) in four bacterial Pseudoalteromonas strains among a culture library of 225 isolates obtained from the crustose coralline algae Neogoniolithon fosliei and Hydrolithon onkodes. Coral planulae transformed into fully developed polyps within 6 h, but only a small proportion of these polyps attached to the substratum. The biofilm cell density of the four bacterial strains had no influence on the ratio of attached vs. non-attached polyps. Larval bioassays with ethanolic extracts of the bacterial isolates, as well as synthetic TBP resulted in consistent responses of coral planulae to various doses of TBP. The lowest bacterial density of one of the Pseudoalteromonas strains which induced metamorphosis was 7,000 cells mm(-2) in laboratory assays, which is on the order of 0.1-1% of the total numbers of bacteria typically found on such surfaces. These results, in which an actual cue from bacteria has been characterized for the first time, contribute significantly towards understanding the complex process of acroporid coral larval settlement mediated through epibiotic microbial biofilms on crustose coralline algae.

  14. Induction of Larval Metamorphosis of the Coral Acropora millepora by Tetrabromopyrrole Isolated from a Pseudoalteromonas Bacterium

    PubMed Central

    Tebben, Jan; Tapiolas, Dianne M.; Motti, Cherie A.; Abrego, David; Negri, Andrew P.; Blackall, Linda L.; Steinberg, Peter D.; Harder, Tilmann

    2011-01-01

    The induction of larval attachment and metamorphosis of benthic marine invertebrates is widely considered to rely on habitat specific cues. While microbial biofilms on marine hard substrates have received considerable attention as specific signals for a wide and phylogenetically diverse array of marine invertebrates, the presumed chemical settlement signals produced by the bacteria have to date not been characterized. Here we isolated and fully characterized the first chemical signal from bacteria that induced larval metamorphosis of acroporid coral larvae (Acropora millepora). The metamorphic cue was identified as tetrabromopyrrole (TBP) in four bacterial Pseudoalteromonas strains among a culture library of 225 isolates obtained from the crustose coralline algae Neogoniolithon fosliei and Hydrolithon onkodes. Coral planulae transformed into fully developed polyps within 6 h, but only a small proportion of these polyps attached to the substratum. The biofilm cell density of the four bacterial strains had no influence on the ratio of attached vs. non-attached polyps. Larval bioassays with ethanolic extracts of the bacterial isolates, as well as synthetic TBP resulted in consistent responses of coral planulae to various doses of TBP. The lowest bacterial density of one of the Pseudoalteromonas strains which induced metamorphosis was 7,000 cells mm−2 in laboratory assays, which is on the order of 0.1 –1% of the total numbers of bacteria typically found on such surfaces. These results, in which an actual cue from bacteria has been characterized for the first time, contribute significantly towards understanding the complex process of acroporid coral larval settlement mediated through epibiotic microbial biofilms on crustose coralline algae. PMID:21559509

  15. Cloning, expression and characterization of a lipase gene from marine bacterium Pseudoalteromonas lipolytica SCSIO 04301

    NASA Astrophysics Data System (ADS)

    Su, Hongfei; Mai, Zhimao; Zhang, Si

    2016-12-01

    A lipase gene, lip1233, isolated from Pseudoalteromonas lipolytica SCSIO 04301, was cloned and expressed in E. coli. The enzyme comprised 810 amino acid residues with a deduced molecular weight of 80 kDa. Lip1233 was grouped into the lipase family X because it contained a highly conserved motif GHSLG. The recombinant enzyme was purified with Ni-NTA affinity chromatography. The optimal temperature and pH value of Lip1233 were 45°C and 8.0, respectively. It retained more than 70% of original activity after being incubated in pH ranging from 6.0 to 9.5 for 30 min. It was stable when the temperature was below 45°C, but was unstable when the temperature was above 55°C. Most metal ions tested had no significant effect on the activity of Lip1233. Lip1233 remained more than original activity in some organic solvents at the concentration of 30% (v/v). It retained more than 30% activity after incubated in pure organic solvents for 12 h, while in hexane the activity was nearly 100%. Additionally, Lip1233 exhibited typical halotolerant characteristic as it was active under 4M NaCl. Lip1233 powder could catalyze efficiently the synthesis of fructose esters in hexane at 40°C. These characteristics demonstrated that Lip1233 is applicable to elaborate food processing and organic synthesis.

  16. Marine Bacteria from Danish Coastal Waters Show Antifouling Activity against the Marine Fouling Bacterium Pseudoalteromonas sp. Strain S91 and Zoospores of the Green Alga Ulva australis Independent of Bacteriocidal Activity▿†

    PubMed Central

    Bernbom, Nete; Ng, Yoke Yin; Kjelleberg, Staffan; Harder, Tilmann; Gram, Lone

    2011-01-01

    The aims of this study were to determine if marine bacteria from Danish coastal waters produce antifouling compounds and if antifouling bacteria could be ascribed to specific niches or seasons. We further assess if antibacterial effect is a good proxy for antifouling activity. We isolated 110 bacteria with anti-Vibrio activity from different sample types and locations during a 1-year sampling from Danish coastal waters. The strains were identified as Pseudoalteromonas, Phaeobacter, and Vibrionaceae based on phenotypic tests and partial 16S rRNA gene sequence similarity. The numbers of bioactive bacteria were significantly higher in warmer than in colder months. While some species were isolated at all sampling locations, others were niche specific. We repeatedly isolated Phaeobacter gallaeciensis at surfaces from one site and Pseudoalteromonas tunicata at two others. Twenty-two strains, representing the major taxonomic groups, different seasons, and isolation strategies, were tested for antiadhesive effect against the marine biofilm-forming bacterium Pseudoalteromonas sp. strain S91 and zoospores of the green alga Ulva australis. The antiadhesive effects were assessed by quantifying the number of strain S91 or Ulva spores attaching to a preformed biofilm of each of the 22 strains. The strongest antifouling activity was found in Pseudoalteromonas strains. Biofilms of Pseudoalteromonas piscicida, Pseudoalteromonas tunicata, and Pseudoalteromonas ulvae prevented Pseudoalteromonas S91 from attaching to steel surfaces. P. piscicida killed S91 bacteria in the suspension cultures, whereas P. tunicata and P. ulvae did not; however, they did prevent adhesion by nonbactericidal mechanism(s). Seven Pseudoalteromonas species, including P. piscicida and P. tunicata, reduced the number of settling Ulva zoospores to less than 10% of the number settling on control surfaces. The antifouling alpP gene was detected only in P. tunicata strains (with purple and yellow pigmentation), so

  17. Marine bacteria from Danish coastal waters show antifouling activity against the marine fouling bacterium Pseudoalteromonas sp. strain S91 and zoospores of the green alga Ulva australis independent of bacteriocidal activity.

    PubMed

    Bernbom, Nete; Ng, Yoke Yin; Kjelleberg, Staffan; Harder, Tilmann; Gram, Lone

    2011-12-01

    The aims of this study were to determine if marine bacteria from Danish coastal waters produce antifouling compounds and if antifouling bacteria could be ascribed to specific niches or seasons. We further assess if antibacterial effect is a good proxy for antifouling activity. We isolated 110 bacteria with anti-Vibrio activity from different sample types and locations during a 1-year sampling from Danish coastal waters. The strains were identified as Pseudoalteromonas, Phaeobacter, and Vibrionaceae based on phenotypic tests and partial 16S rRNA gene sequence similarity. The numbers of bioactive bacteria were significantly higher in warmer than in colder months. While some species were isolated at all sampling locations, others were niche specific. We repeatedly isolated Phaeobacter gallaeciensis at surfaces from one site and Pseudoalteromonas tunicata at two others. Twenty-two strains, representing the major taxonomic groups, different seasons, and isolation strategies, were tested for antiadhesive effect against the marine biofilm-forming bacterium Pseudoalteromonas sp. strain S91 and zoospores of the green alga Ulva australis. The antiadhesive effects were assessed by quantifying the number of strain S91 or Ulva spores attaching to a preformed biofilm of each of the 22 strains. The strongest antifouling activity was found in Pseudoalteromonas strains. Biofilms of Pseudoalteromonas piscicida, Pseudoalteromonas tunicata, and Pseudoalteromonas ulvae prevented Pseudoalteromonas S91 from attaching to steel surfaces. P. piscicida killed S91 bacteria in the suspension cultures, whereas P. tunicata and P. ulvae did not; however, they did prevent adhesion by nonbactericidal mechanism(s). Seven Pseudoalteromonas species, including P. piscicida and P. tunicata, reduced the number of settling Ulva zoospores to less than 10% of the number settling on control surfaces. The antifouling alpP gene was detected only in P. tunicata strains (with purple and yellow pigmentation), so

  18. Cloning, Expression, and Characterization of a Novel L-Arabinose Isomerase from the Psychrotolerant Bacterium Pseudoalteromonas haloplanktis.

    PubMed

    Xu, Wei; Fan, Chen; Zhang, Tao; Jiang, Bo; Mu, Wanmeng

    2016-11-01

    L-Arabinose isomerase (L-AI, EC 5.3.1.4) catalyzes the isomerization between L-arabinose and L-ribulose, and most of the reported ones can also catalyze D-galactose to D-tagatose, except Bacillus subtilis L-AI. In this article, the L-AI from the psychrotolerant bacterium Pseudoalteromonas haloplanktis ATCC 14393 was characterized. The enzyme showed no substrate specificity toward D-galactose, which was similar to B. subtilis L-AI but distinguished from other reported L-AIs. The araA gene encoding the P. haloplanktis L-AI was cloned and overexpressed in E. coli BL21 (DE3). The recombinant enzyme was purified by one-step nickel affinity chromatography . The enzyme displayed the maximal activity at 40 °C and pH 8.0, and showed more than 75 % of maximal activity from pH 7.5-9.0. Metal ion Mn(2+) was required as optimum metal cofactor for activity simulation, but it did not play a significant role in thermostability improvement as reported previously. The Michaelis-Menten constant (K m), turnover number (k cat), and catalytic efficiency (k cat/K m) for substrate L-arabinose were measured to be 111.68 mM, 773.30/min, and 6.92/mM/min, respectively. The molecular docking results showed that the active site residues of P. haloplanktis L-AI could only immobilize L-arabinose and recognized it as substrate for isomerization.

  19. Crystallization and preliminary X-ray crystallographic studies of a psychrophilic subtilisin-like protease Apa1 from Antarctic Pseudoalteromonas sp. strain AS-11.

    PubMed

    Dong, Danghong; Ihara, Tokuo; Motoshima, Hiroyuki; Watanabe, Keiichi

    2005-03-01

    The psychrophilic alkaline serine protease Apa1 secreted by the Antarctic psychrotroph Pseudoalteromonas sp. strain AS-11 consists of a subtilisin-like region (293 residues) and an additional insert region (148 residues) that does not show a sequence homology to any proteins in the RCSB Protein Data Bank. Apa1 inhibited with phenylmethanesulfonyl fluoride has been crystallized and X-ray diffraction data have been collected to 1.78 A resolution. The crystals belong to space group C2, with unit-cell parameters a = 122.94, b = 138.48, c = 64.77 A, alpha = gamma = 90, beta = 97.5 degrees. A molecular-replacement solution has been found using the structure of the mesophilic counterpart subtilisin DY with 38% sequence identity to the catalytic domain of Apa1 as a search model. This is the first crystallographic study of a cold-adapted subtilisin-like protease.

  20. Molecular adaptations in Antarctic fish and marine microorganisms.

    PubMed

    Giordano, Daniela; Russo, Roberta; di Prisco, Guido; Verde, Cinzia

    2012-06-01

    The Antarctic marine environment is one of the most extreme on Earth due to its stably low temperature and high oxygen content. Here we discuss various aspects of the molecular adaptations evolved by Antarctic fish and marine microorganisms living in this environment. This review will in particular focus on: (i) the genetic/genomic bases of adaptation in Antarctic notothenioid fish; (ii) the role of neuroglobin recently identified in the brain of Antarctic icefish; (iii) the structural and functional features of globins of the Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125.

  1. Cloning and characterization of a new κ-carrageenase gene from marine bacterium Pseudoalteromonas sp. QY203

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoyan; Li, Shangyong; Yang, Xuemei; Yu, Wengong; Han, Feng

    2015-12-01

    κ-carrageenan oligosaccharides exhibit various biological activities. Enzymatic degradation by κ-carrageenase is safe and controllable. Therefore, κ-carrageenases have captured more and more attentions. In this study, a κ-carrageenase encoding gene, cgkX, was cloned from Pseudoalteromonas sp. QY203 with degenerate and inverse PCR. It comprised an ORF of 1194 bp in length, encoding a protein with 397 amino acid residues. CgkX is a new member of glycoside hydrolase family 16. The deduced amino acid sequence shared a high similarity with CgkX of Pseudoalteromonas κ-carrageenase; however, the recombinant CgkX showed different biochemical characteristics. The recombinant enzyme was most active at pH 7.0 and 55°C in the presence of 300 mmol L-1 NaCl. It was stable in a broad range of acidity ranging from pH 3.0 to pH 10.0 when temperature was below 40°C. More than 80% of its activity was maintained after being incubated at pH 3.6-10.0 and 4°C for 24 h. CgkX retained more than 90% of activity after being incubated at 40°C for 1 h. EDTA and SDS (1 mmol L-1) did not inhibit its activity. CgkX hydrolyzed κ-carrageenan into disaccharide and tetrasaccharide as an endo-cleaver. All these characteristics demonstrated that CgkX is applicable to both κ-carrageenan oligosaccharide production and κ-carrageenase structure-function research.

  2. Structure and ecological roles of a novel exopolysaccharide from the arctic sea ice bacterium Pseudoalteromonas sp. Strain SM20310.

    PubMed

    Liu, Sheng-Bo; Chen, Xiu-Lan; He, Hai-Lun; Zhang, Xi-Ying; Xie, Bin-Bin; Yu, Yong; Chen, Bo; Zhou, Bai-Cheng; Zhang, Yu-Zhong

    2013-01-01

    The structure and ecological roles of the exopolysaccharides (EPSs) from sea ice microorganisms are poorly studied. Here we show that strain SM20310, with an EPS production of 567 mg liter(-1), was screened from 110 Arctic sea ice isolates and identified as a Pseudoalteromonas strain. The EPS secreted by SM20310 was purified, and its structural characteristics were studied. The predominant repeating unit of this EPS is a highly complicated α-mannan with a molecular mass greater than 2 × 10(6) Da. The backbone of the EPS consists of 2-α-, 6-α-mannosyl residues, in which a considerable part of the 6-α-mannosyl residues are branched at the 2 position with either single t-mannosyl residues or two mannosyl residues. The structure of the described EPS is different from the structures of EPSs secreted by other marine bacteria. Analysis of the ecological roles of the identified EPS showed that the EPS could significantly enhance the high-salinity tolerance of SM20310 and improve the survival of SM20310 after freeze-thaw cycles. These results suggest that the EPS secreted by strain SM20310 enables the strain to adapt to the sea ice environment, which is characterized by low temperature, high salinity, and repeated freeze-thaw cycles. In addition to its functions in strain SM20310, this EPS also significantly improved the tolerance of Escherichia coli to freeze-thaw cycles, suggesting that it may have a universal impact on microorganism cryoprotection.

  3. A Coralline Algal-Associated Bacterium, Pseudoalteromonas Strain J010, Yields Five New Korormicins and a Bromopyrrole

    PubMed Central

    Tebben, Jan; Motti, Cherie; Tapiolas, Dianne; Thomas-Hall, Peter; Harder, Tilmann

    2014-01-01

    The ethanol extract of Pseudoalteromonas strain J010, isolated from the surface of the crustose coralline alga Neogoniolithon fosliei, yielded thirteen natural products. These included a new bromopyrrole, 4′-((3,4,5-tribromo-1H-pyrrol-2-yl)methyl)phenol (1) and five new korormicins G–K (2–6). Also isolated was the known inducer of coral larval metamorphosis, tetrabromopyrrole (TBP), five known korormicins (A–E, previously named 1, 1a–c and 3) and bromoalterochromide A (BAC-A). Structures of the new compounds were elucidated through interpretation of spectra obtained after extensive NMR and MS investigations and comparison with literature values. The antibacterial, antifungal and antiprotozoal potential of 1–6, TBP and BAC-A was assessed. Compounds 1–6 showed antibacterial activity while BAC-A exhibited antiprotozoal properties against Tetrahymena pyriformis. TBP was found to have broad-spectrum activity against all bacteria, the protozoan and the fungus Candida albicans. PMID:24828288

  4. Cryoprotective properties and preliminary characterization of exopolysaccharide (P-Arcpo 15) produced by the Arctic bacterium Pseudoalteromonas elyakovii Arcpo 15.

    PubMed

    Kim, Sung Jin; Kim, Byung-Gee; Park, Ha Ju; Yim, Joung Han

    2016-01-01

    Twenty-two bacterial strains that secrete exopolysaccharides (EPS) were isolated from marine samples obtained from the Chukchi Sea in the Arctic Ocean; of these, seven strains were found to be capable of producing cryoprotective EPS. The ArcPo 15 strain was isolated based on its ability to secrete large amounts of EPS, and was identified as Pseudoalteromonas elyakovii based on 16S rDNA analysis. The EPS, P-ArcPo 15, was purified by protease treatment and gel filtration chromatography. The purified EPS (P-ArcPo 15) had a molecular mass of 1.7 × 10(7) Da, and its infrared spectrum showed absorption bands of hydroxyl and carboxyl groups. The principal sugar components of P-ArcPo 15 were determined to be mannose and galacturonic acid, in the ratio of 3.3:1.0. The cryoprotective properties of P-ArcPo 15 were characterized by an Escherichia coli viability test. In the presence of 0.5% (w/v) EPS, the survival percentage of E. coli cells was as high as 94.19 ± 7.81% over five repeated freeze-thaw cycles. These biochemical characteristics suggest that the EPS P-ArcPo 15 may be useful in the development of cryoprotectants for biotechnological purposes, and we therefore assessed the utility of this novel cryoprotective EPS.

  5. Structural and Functional Characterization of Mature Forms of Metalloprotease E495 from Arctic Sea-Ice Bacterium Pseudoalteromonas sp. SM495

    PubMed Central

    Chen, Xiu-Lan; Xie, Bin-Bin; Zhang, Xi-Ying; Yu, Yong; Chen, Bo; Zhou, Bai-Cheng; Zhang, Yu-Zhong

    2012-01-01

    E495 is the most abundant protease secreted by the Arctic sea-ice bacterium Pseudoalteromonas sp. SM495. As a thermolysin family metalloprotease, E495 was found to have multiple active forms in the culture of strain SM495. E495-M (containing only the catalytic domain) and E495-M-C1 (containing the catalytic domain and one PPC domain) were two stable mature forms, and E495-M-C1-C2 (containing the catalytic domain and two PPC domains) might be an intermediate. Compared to E495-M, E495-M-C1 had similar affinity and catalytic efficiency to oligopeptides, but higher affinity and catalytic efficiency to proteins. The PPC domains from E495 were expressed as GST-fused proteins. Both of the recombinant PPC domains were shown to have binding ability to proteins C-phycocyanin and casein, and domain PPC1 had higher affinity to C-phycocyanin than domain PPC2. These results indicated that the domain PPC1 in E495-M-C1 could be helpful in binding protein substrate, and therefore, improving the catalytic efficiency. Site-directed mutagenesis on the PPC domains showed that the conserved polar and aromatic residues, D26, D28, Y30, Y/W65, in the PPC domains played key roles in protein binding. Our study may shed light on the mechanism of organic nitrogen degradation in the Arctic sea ice. PMID:22523598

  6. Effects of incubation temperature on growth and production of exopolysaccharides by an antarctic sea ice bacterium grown in batch culture.

    PubMed

    Nichols, Carol Mancuso; Bowman, John P; Guezennec, Jean

    2005-07-01

    The sea ice microbial community plays a key role in the productivity of the Southern Ocean. Exopolysaccharide (EPS) is a major component of the exopolymer secreted by many marine bacteria to enhance survival and is abundant in sea ice brine channels, but little is known about its function there. This study investigated the effects of temperature on EPS production in batch culture by CAM025, a marine bacterium isolated from sea ice sampled from the Southern Ocean. Previous studies have shown that CAM025 is a member of the genus Pseudoalteromonas and therefore belongs to a group found to be abundant in sea ice by culture-dependent and -independent techniques. Batch cultures were grown at -2 degrees C, 10 degrees C, and 20 degrees C, and cell number, optical density, pH, glucose concentration, and viscosity were monitored. The yield of EPS at -2 degrees C and 10 degrees C was 30 times higher than at 20 degrees C, which is the optimum growth temperature for many psychrotolerant strains. EPS may have a cryoprotective role in brine channels of sea ice, where extremes of high salinity and low temperature impose pressures on microbial growth and survival. The EPS produced at -2 degrees C and 10 degrees C had a higher uronic acid content than that produced at 20 degrees C. The availability of iron as a trace metal is of critical importance in the Southern Ocean, where it is known to limit primary production. EPS from strain CAM025 is polyanionic and may bind dissolved cations such at trace metals, and therefore the presence of bacterial EPS in the Antarctic marine environment may have important ecological implications.

  7. Tolerance of an Antarctic Bacterium to Multiple Environmental Stressors.

    PubMed

    Sengupta, Dipanwita; Sangu, Kavya; Shivaji, Sisinthy; Chattopadhyay, Madhab K

    2015-10-01

    A population of cold-tolerant Antarctic bacteria was screened for their ability to tolerate other environmental stress factors. Besides low temperature, they were predominantly found to be tolerant to alkali. Attempt was also made to postulate a genetic basis of their multistress-tolerance. Transposon mutagenesis of an isolate Pseudomonas syringae Lz4W was performed, and mutants with delayed growth at low temperature were further screened for sensitivity to some other stress factors. A number of multistress-sensitive mutants were isolated. The mutated gene in one of the mutants sensitive to low temperature, acid and alkali was found to encode citrate synthase. Possible role of citrate synthase in conferring multistress-tolerance was postulated.

  8. Molybdate Reduction to Molybdenum Blue by an Antarctic Bacterium

    PubMed Central

    Ahmad, S. A.; Shukor, M. Y.; Shamaan, N. A.; Mac Cormack, W. P.; Syed, M. A.

    2013-01-01

    A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo6+ to molybdenum blue (Mo-blue). Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries. PMID:24381945

  9. A hyperactive, Ca2+-dependent antifreeze protein in an Antarctic bacterium.

    PubMed

    Gilbert, Jack A; Davies, Peter L; Laybourn-Parry, Johanna

    2005-04-01

    In cold climates, some plants and bacteria that cannot avoid freezing use antifreeze proteins (AFPs) to lessen the destructive effects of ice recrystallization. These AFPs have weak freezing point depression activity, perhaps to avoid sudden, uncontrolled growth of ice. Here, we report on an uncharacteristically powerful bacterial AFP found in an Antarctic strain of the bacterium, Marinomonas primoryensis. It is Ca(2+)-dependent, shows evidence of cooperativity, and can produce over 2 degrees C of freezing point depression. Unlike most AFPs, it does not produce obvious crystal faceting during thermal hysteresis. This AFP might be capable of imparting freezing avoidance to M. primoryensis in ice-covered Antarctic lakes. A hyperactive bacterial AFP has not previously been reported.

  10. Exopolysaccharide of Antarctic bacterium Pseudoaltermonas sp. S-5 induces apoptosis in K562 cells.

    PubMed

    Chen, Guochuang; Qian, Wen; Li, Jing; Xu, Yanghui; Chen, Kaoshan

    2015-05-05

    The aim of this study was to investigate the anticancer activity of exopolysaccharide (PEP) of Antarctic bacterium Pseudoaltermonas sp. S-5 and elucidate the underlying molecular mechanisms. PEP significantly inhibited the growth of human leukemia K562 cells. Results of morphological characterization showed that PEP-treated cells displayed typical morphological characteristics of apoptosis such as condensation of chromatin and formation of apoptotic bodies. Flow cytometry analyses and colorimetric assay demonstrated that PEP induced collapse of mitochondrial membrane potential and activation of caspase-9, which indicated that intrinsic apoptotic signaling pathway was involved in apoptosis induced by PEP in K562 cells. Western blot analysis showed that PEP increased the ratio of Bax/Bcl-2. In addition, calcium signal might contribute to the cytotoxicity of PEP against K562 cells. These findings suggest that PEP may be potentially effective drug against human leukemia.

  11. An ice-binding protein from an Antarctic sea ice bacterium.

    PubMed

    Raymond, James A; Fritsen, Christian; Shen, Kate

    2007-08-01

    An Antarctic sea ice bacterium of the Gram-negative genus Colwellia, strain SLW05, produces an extracellular substance that changes the morphology of growing ice. The active substance was identified as a approximately 25-kDa protein that was purified through its affinity for ice. The full gene sequence was determined and was found to encode a 253-amino acid protein with a calculated molecular mass of 26,350 Da. The predicted amino acid sequence is similar to predicted sequences of ice-binding proteins recently found in two species of sea ice diatoms and a species of snow mold. A recombinant ice-binding protein showed ice-binding activity and ice recrystallization inhibition activity. The protein is much smaller than bacterial ice-nucleating proteins and antifreeze proteins that have been previously described. The function of the protein is unknown but it may act as an ice recrystallization inhibitor to protect membranes in the frozen state.

  12. Ca2+-stabilized adhesin helps an Antarctic bacterium reach out and bind ice

    PubMed Central

    Vance, Tyler D. R.; Olijve, Luuk L. C.; Campbell, Robert L.; Voets, Ilja K.; Davies, Peter L.; Guo, Shuaiqi

    2014-01-01

    The large size of a 1.5-MDa ice-binding adhesin [MpAFP (Marinomonas primoryensis antifreeze protein)] from an Antarctic Gram-negative bacterium, M. primoryensis, is mainly due to its highly repetitive RII (Region II). MpAFP_RII contains roughly 120 tandem copies of an identical 104-residue repeat. We have previously determined that a single RII repeat folds as a Ca2+-dependent immunoglobulin-like domain. Here, we solved the crystal structure of RII tetra-tandemer (four tandem RII repeats) to a resolution of 1.8 Å. The RII tetra-tandemer reveals an extended (~190-Å × ~25-Å), rod-like structure with four RII-repeats aligned in series with each other. The inter-repeat regions of the RII tetra-tandemer are strengthened by Ca2+ bound to acidic residues. SAXS (small-angle X-ray scattering) profiles indicate the RII tetra-tandemer is significantly rigidified upon Ca2+ binding, and that the protein's solution structure is in excellent agreement with its crystal structure. We hypothesize that >600 Ca2+ help rigidify the chain of ~120 104-residue repeats to form a ~0.6 μm rod-like structure in order to project the ice-binding domain of MpAFP away from the bacterial cell surface. The proposed extender role of RII can help the strictly aerobic, motile bacterium bind ice in the upper reaches of the Antarctic lake where oxygen and nutrients are most abundant. Ca2+-induced rigidity of tandem Ig-like repeats in large adhesins might be a general mechanism used by bacteria to bind to their substrates and help colonize specific niches. PMID:24892750

  13. Ca2+-stabilized adhesin helps an Antarctic bacterium reach out and bind ice.

    PubMed

    Vance, Tyler D R; Olijve, Luuk L C; Campbell, Robert L; Voets, Ilja K; Davies, Peter L; Guo, Shuaiqi

    2014-07-04

    The large size of a 1.5-MDa ice-binding adhesin [MpAFP (Marinomonas primoryensis antifreeze protein)] from an Antarctic Gram-negative bacterium, M. primoryensis, is mainly due to its highly repetitive RII (Region II). MpAFP_RII contains roughly 120 tandem copies of an identical 104-residue repeat. We have previously determined that a single RII repeat folds as a Ca2+-dependent immunoglobulin-like domain. Here, we solved the crystal structure of RII tetra-tandemer (four tandem RII repeats) to a resolution of 1.8 Å. The RII tetra-tandemer reveals an extended (~190-Å × ~25-Å), rod-like structure with four RII-repeats aligned in series with each other. The inter-repeat regions of the RII tetra-tandemer are strengthened by Ca2+ bound to acidic residues. SAXS (small-angle X-ray scattering) profiles indicate the RII tetra-tandemer is significantly rigidified upon Ca2+ binding, and that the protein's solution structure is in excellent agreement with its crystal structure. We hypothesize that >600 Ca2+ help rigidify the chain of ~120 104-residue repeats to form a ~0.6 μm rod-like structure in order to project the ice-binding domain of MpAFP away from the bacterial cell surface. The proposed extender role of RII can help the strictly aerobic, motile bacterium bind ice in the upper reaches of the Antarctic lake where oxygen and nutrients are most abundant. Ca2+-induced rigidity of tandem Ig-like repeats in large adhesins might be a general mechanism used by bacteria to bind to their substrates and help colonize specific niches.

  14. Rhodoferax antarcticus sp. nov., a moderately psychrophilic purple nonsulfur bacterium isolated from an Antarctic microbial mat

    NASA Technical Reports Server (NTRS)

    Madigan, M. T.; Jung, D. O.; Woese, C. R.; Achenbach, L. A.

    2000-01-01

    A new species of purple nonsulfur bacteria isolated from an Antarctic microbial mat is described. The organism, designated strain ANT.BR, was mildly psychrophilic, growing optimally at 15-18 degrees C with a growth temperature range of 0-25 degrees C. Cells of strain ANT.BR were highly motile curved rods and spirals, contained bacteriochlorophyll a, and showed a multicomponent in vivo absorption spectrum. A specific phylogenetic relationship was observed between strain ANT.BR and the purple bacterium Rhodoferax fermentans FR2T, and the two organisms shared several physiological and other phenotypic properties, with the notable exception of growth temperature optimum. Tests of genomic DNA hybridization, however, showed Rfx. fermentans FR2T and strain ANT.BR to be genetically distinct bacteria. Because of its unique set of properties, especially its requirement for low growth temperatures, we propose to recognize strain ANT.BR as a new species of the genus Rhodoferax, Rhodoferax antarcticus, named for its known habitat, the Antarctic.

  15. Rhodoferax antarcticus sp. nov., a moderately psychrophilic purple nonsulfur bacterium isolated from an Antarctic microbial mat.

    PubMed

    Madigan, M T; Jung, D O; Woese, C R; Achenbach, L A

    2000-04-01

    A new species of purple nonsulfur bacteria isolated from an Antarctic microbial mat is described. The organism, designated strain ANT.BR, was mildly psychrophilic, growing optimally at 15-18 degrees C with a growth temperature range of 0-25 degrees C. Cells of strain ANT.BR were highly motile curved rods and spirals, contained bacteriochlorophyll a, and showed a multicomponent in vivo absorption spectrum. A specific phylogenetic relationship was observed between strain ANT.BR and the purple bacterium Rhodoferax fermentans FR2T, and the two organisms shared several physiological and other phenotypic properties, with the notable exception of growth temperature optimum. Tests of genomic DNA hybridization, however, showed Rfx. fermentans FR2T and strain ANT.BR to be genetically distinct bacteria. Because of its unique set of properties, especially its requirement for low growth temperatures, we propose to recognize strain ANT.BR as a new species of the genus Rhodoferax, Rhodoferax antarcticus, named for its known habitat, the Antarctic.

  16. Rhodoferax antarcticus sp. nov., a moderately psychrophilic purple nonsulfur bacterium isolated from an Antarctic microbial mat

    NASA Technical Reports Server (NTRS)

    Madigan, M. T.; Jung, D. O.; Woese, C. R.; Achenbach, L. A.

    2000-01-01

    A new species of purple nonsulfur bacteria isolated from an Antarctic microbial mat is described. The organism, designated strain ANT.BR, was mildly psychrophilic, growing optimally at 15-18 degrees C with a growth temperature range of 0-25 degrees C. Cells of strain ANT.BR were highly motile curved rods and spirals, contained bacteriochlorophyll a, and showed a multicomponent in vivo absorption spectrum. A specific phylogenetic relationship was observed between strain ANT.BR and the purple bacterium Rhodoferax fermentans FR2T, and the two organisms shared several physiological and other phenotypic properties, with the notable exception of growth temperature optimum. Tests of genomic DNA hybridization, however, showed Rfx. fermentans FR2T and strain ANT.BR to be genetically distinct bacteria. Because of its unique set of properties, especially its requirement for low growth temperatures, we propose to recognize strain ANT.BR as a new species of the genus Rhodoferax, Rhodoferax antarcticus, named for its known habitat, the Antarctic.

  17. Discovery and Characterization of a Distinctive Exo-1,3/1,4-β-Glucanase from the Marine Bacterium Pseudoalteromonas sp. Strain BB1▿ †

    PubMed Central

    Nakatani, Yoshio; Lamont, Iain L.; Cutfield, John F.

    2010-01-01

    Marine bacteria residing on local red, green, and brown seaweeds were screened for exo-1,3-β-glucanase (ExoP) activity. Of the 90 bacterial species isolated from 32 seaweeds, only one, a Pseudoalteromonas sp., was found to display such activity. It was isolated from a Durvillaea sp., a brown kelp known to contain significant amounts of the storage polysaccharide laminarin (1,3-β-d-glucan with some 1,6-β branching). Four chromatographic steps were utilized to purify the enzyme (ExoP). Chymotryptic digestion provided peptide sequences for primer design and subsequent gene cloning. The exoP gene coded for 840 amino acids and was located just 50 bp downstream from a putative lichenase (endo-1,3-1,4-β-glucanase) gene, suggesting possible cotranscription of these genes. Sequence comparisons revealed ExoP to be clustered within a group of bacterial glycosidases with high similarity to a group of glycoside hydrolase (GH3) plant enzymes, of which the barley exo-1,3/1,4-β-glucanase (ExoI) is the best characterized. The major difference between the bacterial and plant proteins is an extra 200- to 220-amino-acid extension at the C terminus of the former. This additional sequence does not correlate with any known functional domain, but ExoP was not active against laminarin when this region was removed. Production of recombinant ExoP allowed substrate specificity studies to be performed. The enzyme was found to possess similar levels of exoglucanase activity against both 1,4-β linkages and 1,3-β linkages, and so ExoP is designated an exo-1,3/1,4-β-exoglucanase, the first such bacterial enzyme to be characterized. This broader specificity could allow the enzyme to assist in digesting both cell wall cellulose and cytoplasmic laminarin. PMID:20729316

  18. Modulation of violacein production and phenotypes associated with biofilm by exogenous quorum sensing N-acylhomoserine lactones in the marine bacterium Pseudoalteromonas ulvae TC14.

    PubMed

    Mireille Ayé, Armande; Bonnin-Jusserand, Maryse; Brian-Jaisson, Florence; Ortalo-Magné, Annick; Culioli, Gérald; Koffi Nevry, Rose; Rabah, Nadia; Blache, Yves; Molmeret, Maëlle

    2015-10-01

    Various phenotypes ranging from biofilm formation to pigment production have been shown to be regulated by quorum sensing (QS) in many bacteria. However, studies of the regulation of pigments produced by marine bacteria in saline conditions and of biofilm-associated phenotypes are scarcer. This study focuses on the demonstration of the existence of a QS communication system involving N-acylhomoserine lactones (AHLs) in the Mediterranean Sea strain Pseudoalteromonas ulvae TC14. We have investigated whether TC14 produces the violacein pigment, and whether intrinsic or exogenous AHLs could influence its production and modulate biofilm-associated phenotypes. Here, we demonstrate that the purple pigment produced by TC14 is violacein. The study shows that in planktonic conditions, TC14 produces more pigment in the medium in which it grows less. Using different approaches, the results also show that TC14 does not produce intrinsic AHLs in our conditions. When exogenous AHLs are added in planktonic conditions, the production of violacein is upregulated by C6-, C12-, 3-oxo-C8 and 3-oxo-C12-HSLs (homoserine lactones), and downregulated by 3-oxo-C6-HSL. In sessile conditions, 3-oxo-C8-HSL upregulates the production of violacein. The study of the biofilm-associated phenotypes shows that oxo-derived-HSLs decrease adhesion, swimming and biofilm formation. While 3-oxo-C8 and 3-oxo-C12-HSLs decrease both swimming and adhesion, 3-oxo-C6-HSLs decrease not only violacein production in planktonic conditions but also swimming, adhesion and more subtly biofilm formation. Therefore, TC14 may possess a functional LuxR-type QS receptor capable of sensing extrinsic AHLs, which controls violacein production, motility, adhesion and biofilm formation.

  19. Cold adaptation of the mononuclear molybdoenzyme periplasmic nitrate reductase from the Antarctic bacterium Shewanella gelidimarina

    SciTech Connect

    Simpson, Philippa J.L.; Codd, Rachel

    2011-11-04

    Highlights: Black-Right-Pointing-Pointer Cold-adapted phenotype of NapA from the Antarctic bacterium Shewanella gelidimarina. Black-Right-Pointing-Pointer Protein homology model of NapA from S. gelidimarina and mesophilic homologue. Black-Right-Pointing-Pointer Six amino acid residues identified as lead candidates governing NapA cold adaptation. Black-Right-Pointing-Pointer Molecular-level understanding of designing cool-temperature in situ oxyanion sensors. -- Abstract: The reduction of nitrate to nitrite is catalysed in bacteria by periplasmic nitrate reductase (Nap) which describes a system of variable protein subunits encoded by the nap operon. Nitrate reduction occurs in the NapA subunit, which contains a bis-molybdopterin guanine dinucleotide (Mo-MGD) cofactor and one [4Fe-4S] iron-sulfur cluster. The activity of periplasmic nitrate reductase (Nap) isolated as native protein from the cold-adapted (psychrophilic) Antarctic bacterium Shewanella gelidimarina (Nap{sub Sgel}) and middle-temperature adapted (mesophilic) Shewanella putrefaciens (Nap{sub Sput}) was examined at varied temperature. Irreversible deactivation of Nap{sub Sgel} and Nap{sub Sput} occurred at 54.5 and 65 Degree-Sign C, respectively. When Nap{sub Sgel} was preincubated at 21-70 Degree-Sign C for 30 min, the room-temperature nitrate reductase activity was maximal and invariant between 21 and 54 Degree-Sign C, which suggested that Nap{sub Sgel} was poised for optimal catalysis at modest temperatures and, unlike Nap{sub Sput}, did not benefit from thermally-induced refolding. At 20 Degree-Sign C, Nap{sub Sgel} reduced selenate at 16% of the rate of nitrate reduction. Nap{sub Sput} did not reduce selenate. Sequence alignment showed 46 amino acid residue substitutions in Nap{sub Sgel} that were conserved in NapA from mesophilic Shewanella, Rhodobacter and Escherichia species and could be associated with the Nap{sub Sgel} cold-adapted phenotype. Protein homology modeling of Nap{sub Sgel} using a

  20. Thermodynamic stability of a cold-active alpha-amylase from the Antarctic bacterium Alteromonas haloplanctis.

    PubMed

    Feller, G; d'Amico, D; Gerday, C

    1999-04-06

    The thermal stability of the cold-active alpha-amylase (AHA) secreted by the Antarctic bacterium Alteromonas haloplanctis has been investigated by intrinsic fluorescence, circular dichroism, and differential scanning calorimetry. It was found that this heat-labile enzyme is the largest known multidomain protein exhibiting a reversible two-state unfolding, as demonstrated by the recovery of DeltaHcal values after consecutive calorimetric transitions, a DeltaHcal/DeltaHeff ratio close to unity, and the independence of unfolding thermodynamic parameters of scan rates. By contrast, the mesophilic alpha-amylases investigated here (from porcine pancreas, human salivary glands, yellow meal beetle, Bacillus amyloliquefaciens, and Bacillus licheniformis) unfold irreversibly according to a non-two-state mechanism. Unlike mesophilic alpha-amylases, the melting point of AHA is independent of calcium and chloride binding while the allosteric and structural functions of these ions are conserved. The thermostability of AHA at optimal conditions is characterized by a Tm of 43.7 degrees C, a DeltaHcal of 238 kcal mol-1, and a DeltaCp of 8.47 kcal mol-1 K-1. These values were used to calculate the Gibbs free energy of unfolding over a wide range of temperatures. This stability curve shows that (a) the specific DeltaGmax of AHA [22 cal (mol of residue)-1] is 4 times lower than that of mesophilic alpha-amylases, (b) group hydration plays a crucial role in the enzyme flexibility at low temperatures, (c) the temperature of cold unfolding closely corresponds to the lower limit of bacterial growth, and (d) the recombinant heat-labile enzyme can be expressed in mesophilic hosts at moderate temperatures. It is also argued that the cold-active alpha-amylase has evolved toward the lowest possible conformational stability of its native state.

  1. Complete genome sequence of Hymenobacter sp. strain PAMC26554, an ionizing radiation-resistant bacterium isolated from an Antarctic lichen.

    PubMed

    Oh, Tae-Jin; Han, So-Ra; Ahn, Do-Hwan; Park, Hyun; Kim, Augustine Yonghwi

    2016-06-10

    A Gram-negative, rod-shaped, red-pink in color, and UV radiation-resistant bacterium Hymenobacter sp. strain PAMC26554 was isolated from Usnea sp., an Antarctic lichen, and belongs to the class of Cytophagia and the phylum of Bacteroidetes. The complete genome of Hymenobacter sp. PAMC26554 consists of one chromosome (5,244,843bp) with two plasmids (199,990bp and 6421bp). The genomic sequence indicates that Hymenobacter sp. strain PAMC26554 possesses several genes involved in the nucleotide excision repair pathway that protects damaged DNA. This complete genome information will help us to understand its adaptation and novel survival strategy in the Antarctic extreme cold environment.

  2. Pseudoalteromonas haloplanktis produces methylamine, a volatile compound active against Burkholderia cepacia complex strains.

    PubMed

    Sannino, Filomena; Parrilli, Ermenegilda; Apuzzo, Gennaro Antonio; de Pascale, Donatella; Tedesco, Pietro; Maida, Isabel; Perrin, Elena; Fondi, Marco; Fani, Renato; Marino, Gennaro; Tutino, Maria Luisa

    2017-03-25

    The Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125 has been reported to produce several Volatile Organic Compounds (VOCs), which are able to inhibit the growth of Burkholderia cepacia complex (Bcc) strains, opportunistic pathogens responsible for the infection of immune-compromised patients. However, no specific antibacterial VOCs have been identified to date. The purpose of the present study was to identify specific VOCs that contribute to Bcc inhibition by the Antarctic strain. When grown on defined medium containing D-gluconate and L-glutamate as carbon, nitrogen and energy sources, P. haloplanktis TAC125 is unable to inhibit the growth of Bcc strains. However, single addition of several amino acids to the defined medium restores the P. haloplanktis TAC125 inhibition ability. With the aim of identifying specific volatile compound/s responsible for Bcc inhibition, we set up an apparatus for VOC capture, accumulation, and storage. P. haloplanktis TAC125 was grown in an automatic fermenter which was connected to a cooling system to condense VOCs present in the exhaust air outlet. Upon addition of methionine to the growth medium, the VOC methylamine was produced by P. haloplanktis TAC125. Methylamine was found to inhibit the growth of several Bcc strains in a dose-dependent way. Although it was reported that P. haloplanktis TAC125 produces VOCs endowed with antimicrobial activity, this is the first demonstration that methylamine probably contributes to the anti-Bcc activity of P. haloplanktis TAC125 VOCs.

  3. Genome Sequence of the Antarctic Psychrophile Bacterium Planococcus antarcticus DSM 14505

    PubMed Central

    Margolles, Abelardo; Gueimonde, Miguel

    2012-01-01

    Planococcus antarcticus DSM 14505 is a psychrophile bacterium that was isolated from cyanobacterial mat samples, originally collected from ponds in McMurdo, Antarctica. This orange-pigmented bacterium grows at 4°C and may possess interesting enzymatic activities at low temperatures. Here we report the first genomic sequence of P. antarcticus DSM 14505. PMID:22843594

  4. Genome Sequence of Rhodoferax antarcticus ANT.BRT; A Psychrophilic Purple Nonsulfur Bacterium from an Antarctic Microbial Mat

    PubMed Central

    Baker, Jennifer M.; Riester, Carli J.; Skinner, Blair M.; Newell, Austin W.; Swingley, Wesley D.; Madigan, Michael T.; Jung, Deborah O.; Asao, Marie; Chen, Min; Loughlin, Patrick C.; Pan, Hao; Lin, Yuankui; Li, Yaqiong; Shaw, Jacob; Prado, Mindy; Sherman, Chris; Tang, Joseph Kuo-Hsiang; Blankenship, Robert E.; Zhao, Tingting; Touchman, Jeffrey W.; Sattley, W. Matthew

    2017-01-01

    Rhodoferax antarcticus is an Antarctic purple nonsulfur bacterium and the only characterized anoxygenic phototroph that grows best below 20 °C. We present here a high-quality draft genome of Rfx. antarcticus strain ANT.BRT, isolated from an Antarctic microbial mat. The circular chromosome (3.8 Mbp) of Rfx. antarcticus has a 59.1% guanine + cytosine (GC) content and contains 4036 open reading frames. In addition, the bacterium contains a sizable plasmid (198.6 kbp, 48.4% GC with 226 open reading frames) that comprises about 5% of the total genetic content. Surprisingly, genes encoding light-harvesting complexes 1 and 3 (LH1 and LH3), but not light-harvesting complex 2 (LH2), were identified in the photosynthesis gene cluster of the Rfx. antarcticus genome, a feature that is unique among purple phototrophs. Consistent with physiological studies that showed a strong capacity for nitrogen fixation in Rfx. antarcticus, a nitrogen fixation gene cluster encoding a molybdenum-type nitrogenase was present, but no alternative nitrogenases were identified despite the cold-active phenotype of this phototroph. Genes encoding two forms of ribulose 1,5-bisphosphate carboxylase/oxygenase were present in the Rfx. antarcticus genome, a feature that likely provides autotrophic flexibility under varying environmental conditions. Lastly, genes for assembly of both type IV pili and flagella are present, with the latter showing an unusual degree of clustering. This report represents the first genomic analysis of a psychrophilic anoxygenic phototroph and provides a glimpse of the genetic basis for maintaining a phototrophic lifestyle in a permanently cold, yet highly variable, environment. PMID:28230808

  5. Structure of a 1.5-MDa adhesin that binds its Antarctic bacterium to diatoms and ice

    PubMed Central

    Guo, Shuaiqi; Stevens, Corey A.; Vance, Tyler D. R.; Olijve, Luuk L. C.; Graham, Laurie A.; Campbell, Robert L.; Yazdi, Saeed R.; Escobedo, Carlos; Bar-Dolev, Maya; Yashunsky, Victor; Braslavsky, Ido; Langelaan, David N.; Smith, Steven P.; Allingham, John S.; Voets, Ilja K.; Davies, Peter L.

    2017-01-01

    Bacterial adhesins are modular cell-surface proteins that mediate adherence to other cells, surfaces, and ligands. The Antarctic bacterium Marinomonas primoryensis uses a 1.5-MDa adhesin comprising over 130 domains to position it on ice at the top of the water column for better access to oxygen and nutrients. We have reconstructed this 0.6-μm-long adhesin using a “dissect and build” structural biology approach and have established complementary roles for its five distinct regions. Domains in region I (RI) tether the adhesin to the type I secretion machinery in the periplasm of the bacterium and pass it through the outer membrane. RII comprises ~120 identical immunoglobulin-like β-sandwich domains that rigidify on binding Ca2+ to project the adhesion regions RIII and RIV into the medium. RIII contains ligand-binding domains that join diatoms and bacteria together in a mixed-species community on the underside of sea ice where incident light is maximal. RIV is the ice-binding domain, and the terminal RV domain contains several “repeats-in-toxin” motifs and a noncleavable signal sequence that target proteins for export via the type I secretion system. Similar structural architecture is present in the adhesins of many pathogenic bacteria and provides a guide to finding and blocking binding domains to weaken infectivity. PMID:28808685

  6. Draft Genome Sequence of the Volatile Organic Compound-Producing Antarctic Bacterium Arthrobacter sp. Strain TB23, Able To Inhibit Cystic Fibrosis Pathogens Belonging to the Burkholderia cepacia Complex

    PubMed Central

    Fondi, Marco; Orlandini, Valerio; Maida, Isabel; Perrin, Elena; Papaleo, Maria Cristiana; Emiliani, Giovanni; de Pascale, Donatella; Parrilli, Ermenegilda; Tutino, Maria Luisa; Michaud, Luigi; Lo Giudice, Angelina

    2012-01-01

    Arthrobacter sp. strain TB23 was isolated from the Antarctic sponge Lissodendoryx nobilis. This bacterium is able to produce antimicrobial compounds and volatile organic compounds (VOCs) that inhibit the growth of other Antarctic bacteria and of cystic fibrosis opportunistic pathogens, respectively. Here we report the draft genome sequence of Arthrobacter sp. TB23. PMID:23105071

  7. Shewanella vesiculosa sp. nov., a psychrotolerant bacterium isolated from an Antarctic coastal area.

    PubMed

    Bozal, Núria; Montes, Ma Jesus; Miñana-Galbis, David; Manresa, Angeles; Mercadé, Elena

    2009-02-01

    Two strains of psychrotolerant bacteria, designated M7(T) and M5, isolated from Antarctic coastal marine environments were studied to determine their taxonomic position. The organisms comprised Gram-negative, rod-shaped, facultatively anaerobic cells that were motile by means of single polar flagella. Neither of the bacterial isolates had a requirement for Na(+). These two psychrotolerant strains grew at temperatures ranging from -4 to 30 degrees C. Both strains were capable of producing H(2)S from thiosulfate and were able to use sodium nitrate and trimethylamine N-oxide as terminal electron acceptors during anaerobic growth. 16S rRNA gene sequence analysis placed M7(T) and M5 within the genus Shewanella; the strains showed the highest similarity (99.9 and 99.2 % respectively) with respect to the type strains of Shewanella livingstonensis and Shewanella frigidimarina. However the levels of gyrB sequence similarity between strain M7(T) and the type strains of S. livingstonensis and S. frigidimarina were 87.6 and 87.4 %, respectively. DNA-DNA hybridization experiments performed between the Antarctic isolate M7(T) and S. livingstonensis LMG 19866(T) and S. frigidimarina LMG 19475(T) revealed levels of relatedness of 32 and 35 %, respectively. Strain M5 showed 100 % DNA relatedness with respect to strain M7(T). The DNA G+C content of these bacteria was 42 mol%. Several phenotypic characteristics, the cellular fatty acid compositions and the quinone content of strains M7(T) and M5 served to differentiate them from related shewanellae. On the basis of the data from this polyphasic taxonomic study, M7(T) and M5 constitute a single genospecies. They represent a novel species of the genus Shewanella, for which the name Shewanella vesiculosa sp. nov. is proposed. The type strain is M7(T) (=LMG 24424(T) =CECT 7339(T)).

  8. Characterization of a halotolerant-psychroloterant bacterium from dry valley Antarctic soil.

    PubMed

    Miller, K J; Leschine, S B; Huguenin, R L

    1983-01-01

    The saline soils of the ice free dry valleys of Victoria Land, Antarctica may provide the closest analog on Earth to Martian conditions. We have initiated a study aimed at examining microbial adaptations to the harsh environment of these dry valley soils. In this report we describe the characterization of one bacterium, strain A4a, isolated from Taylor Valley soil. Strain A4a was an obligately aerobic, orange-pigmented, Gram-positive coccus that grew over wide ranges of both temperature (0 degrees C-40 degrees C) and sodium chloride concentration (0-2.0M). The optimal temperature for growth at all NaCl concentrations was 25 degrees C. Phospholipid composition and guanine plus cytosine content of the DNA of the isolate indicate a close relation to the genus Planococcus.

  9. Comparative genomics reveals a deep-sea sediment-adapted life style of Pseudoalteromonas sp. SM9913

    PubMed Central

    Qin, Qi-Long; Li, Yang; Zhang, Yan-Jiao; Zhou, Zhe-Min; Zhang, Wei-Xin; Chen, Xiu-Lan; Zhang, Xi-Ying; Zhou, Bai-Cheng; Wang, Lei; Zhang, Yu-Zhong

    2011-01-01

    Deep-sea sediment is one of the most important microbial-driven ecosystems, yet it is not well characterized. Genome sequence analyses of deep-sea sedimentary bacteria would shed light on the understanding of this ecosystem. In this study, the complete genome of deep-sea sedimentary bacterium Pseudoalteromonas sp. SM9913 (SM9913) is described and compared with that of the closely related Antarctic surface sea-water ecotype Pseudoalteromonas haloplanktis TAC125 (TAC125). SM9913 has fewer dioxygenase genes than TAC125, indicating a possible sensitivity to reactive oxygen species. Accordingly, experimental results showed that SM9913 was less tolerant of H2O2 than TAC125. SM9913 has gene clusters related to both polar and lateral flagella biosynthesis. Lateral flagella, which are usually present in deep-sea bacteria and absent in the related surface bacteria, are important for the survival of SM9913 in deep-sea environments. With these two flagellar systems, SM9913 can swim in sea water and swarm on the sediment particle surface, favoring the acquisition of nutrients from particulate organic matter and reflecting the particle-associated alternative lifestyle of SM9913 in the deep sea. A total of 12 genomic islands were identified in the genome of SM9913 that may confer specific features unique to SM9913 and absent from TAC125, such as drug and heavy metal resistance. Many signal transduction genes and a glycogen production operon were also present in the SM9913 genome, which may help SM9913 respond to food pulses and store carbon and energy in a deep-sea environment. PMID:20703316

  10. Sporosarcina antarctica sp. nov., a psychrophilic bacterium isolated from the Antarctic.

    PubMed

    Yu, Yong; Xin, Yu-Hua; Liu, Hong-Can; Chen, Bo; Sheng, Jun; Chi, Zhen-Ming; Zhou, Pei-Jin; Zhang, De-Chao

    2008-09-01

    A Gram-positive, psychrophilic, rod-shaped bacterium, designated strain N-05(T), was isolated from soil samples collected off King George Island, west Antarctica (6 degrees 13' 31'' S 5 degrees 57' 08'' W). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain N-05(T) was related to members of the genus Sporosarcina and had highest 16S rRNA gene sequence similarity with the type strain of Sporosarcina macmurdoensis (98.0%). The temperature range for growth of strain N-05(T) was 0-23 degrees C, with optimum growth occurring at 17-18 degrees C and approximately pH 6.0-8.0. Strain N-05(T) had MK-7 as the major menaquinone and anteiso-C(15:0) and C(16:1)omega7c alcohol as major fatty acids. The genomic DNA G+C content was 39.2 mol%. On the basis of phenotypic characteristics, phylogenetic analysis and DNA-DNA relatedness data, strain N-05(T) is considered to represent a novel species of the genus Sporosarcina, for which the name Sporosarcina antarctica is proposed. The type strain is N-05(T) (=CGMCC 1.6503(T)=JCM 14646(T)).

  11. Novel Essential Role of Ethanol Oxidation Genes at Low Temperature Revealed by Transcriptome Analysis in the Antarctic Bacterium Pseudomonas extremaustralis.

    PubMed

    Tribelli, Paula M; Solar Venero, Esmeralda C; Ricardi, Martiniano M; Gómez-Lozano, Maria; Raiger Iustman, Laura J; Molin, Søren; López, Nancy I

    2015-01-01

    Temperature is one of the most important factors for bacterial growth and development. Cold environments are widely distributed on earth, and psychrotolerant and psychrophilic microorganisms have developed different adaptation strategies to cope with the stress derived from low temperatures. Pseudomonas extremaustralis is an Antarctic bacterium able to grow under low temperatures and to produce high amounts of polyhydroxyalkanoates (PHAs). In this work, we analyzed the genome-wide transcriptome by RNA deep-sequencing technology of early exponential cultures of P. extremaustralis growing in LB (Luria Broth) supplemented with sodium octanoate to favor PHA accumulation at 8°C and 30°C. We found that genes involved in primary metabolism, including tricarboxylic acid cycle (TCA) related genes, as well as cytochromes and amino acid metabolism coding genes, were repressed at low temperature. Among up-regulated genes, those coding for transcriptional regulatory and signal transduction proteins were over-represented at cold conditions. Remarkably, we found that genes involved in ethanol oxidation, exaA, exaB and exaC, encoding a pyrroloquinoline quinone (PQQ)-dependent ethanol dehydrogenase, the cytochrome c550 and an aldehyde dehydrogenase respectively, were up-regulated. Along with RNA-seq experiments, analysis of mutant strains for pqqB (PQQ biosynthesis protein B) and exaA were carried out. We found that the exaA and pqqB genes are essential for growth under low temperature in LB supplemented with sodium octanoate. Additionally, p-rosaniline assay measurements showed the presence of alcohol dehydrogenase activity at both 8°C and 30°C, while the activity was abolished in a pqqB mutant strain. These results together with the detection of ethanol by gas chromatography in P. extremaustralis cultures grown at 8°C support the conclusion that this pathway is important under cold conditions. The obtained results have led to the identification of novel components involved

  12. Novel Essential Role of Ethanol Oxidation Genes at Low Temperature Revealed by Transcriptome Analysis in the Antarctic Bacterium Pseudomonas extremaustralis

    PubMed Central

    Tribelli, Paula M.; Solar Venero, Esmeralda C.; Ricardi, Martiniano M.; Gómez-Lozano, Maria; Raiger Iustman, Laura J.; Molin, Søren; López, Nancy I.

    2015-01-01

    Temperature is one of the most important factors for bacterial growth and development. Cold environments are widely distributed on earth, and psychrotolerant and psychrophilic microorganisms have developed different adaptation strategies to cope with the stress derived from low temperatures. Pseudomonas extremaustralis is an Antarctic bacterium able to grow under low temperatures and to produce high amounts of polyhydroxyalkanoates (PHAs). In this work, we analyzed the genome-wide transcriptome by RNA deep-sequencing technology of early exponential cultures of P. extremaustralis growing in LB (Luria Broth) supplemented with sodium octanoate to favor PHA accumulation at 8°C and 30°C. We found that genes involved in primary metabolism, including tricarboxylic acid cycle (TCA) related genes, as well as cytochromes and amino acid metabolism coding genes, were repressed at low temperature. Among up-regulated genes, those coding for transcriptional regulatory and signal transduction proteins were over-represented at cold conditions. Remarkably, we found that genes involved in ethanol oxidation, exaA, exaB and exaC, encoding a pyrroloquinoline quinone (PQQ)-dependent ethanol dehydrogenase, the cytochrome c550 and an aldehyde dehydrogenase respectively, were up-regulated. Along with RNA-seq experiments, analysis of mutant strains for pqqB (PQQ biosynthesis protein B) and exaA were carried out. We found that the exaA and pqqB genes are essential for growth under low temperature in LB supplemented with sodium octanoate. Additionally, p-rosaniline assay measurements showed the presence of alcohol dehydrogenase activity at both 8°C and 30°C, while the activity was abolished in a pqqB mutant strain. These results together with the detection of ethanol by gas chromatography in P. extremaustralis cultures grown at 8°C support the conclusion that this pathway is important under cold conditions. The obtained results have led to the identification of novel components involved

  13. Ionic liquids increase the catalytic efficiency of a lipase (Lip1) from an antarctic thermophilic bacterium.

    PubMed

    Muñoz, Patricio A; Correa-Llantén, Daniela N; Blamey, Jenny M

    2015-01-01

    Lipases catalyze the hydrolysis and synthesis of triglycerides and their reactions are widely used in industry. The use of ionic liquids has been explored in order to improve their catalytic properties. However, the effect of these compounds on kinetic parameters of lipases has been poorly understood. A study of the kinetic parameters of Lip1, the most thermostable lipase from the supernatant of the strain ID17, a thermophilic bacterium isolated from Deception Island, Antarctica, and a member of the genus Geobacillus is presented. Kinetic parameters of Lip1 were modulated by the use of ionic liquids BmimPF6 and BmimBF4. The maximum reaction rate of Lip1 was improved in the presence of both salts. The highest effect was observed when BmimPF6 was added in the reaction mix, resulting in a higher hydrolytic activity and in a modulation of the catalytic efficiency of the enzyme. However, the catalytic efficiency did not change in the presence of BmimBF4. The increase of the reaction rates of Lip1 promoted by these ionic liquids could be related to possible changes in the Lip1 structure. This effect was measured by quenching of tryptophan fluorescence of the enzyme, when it was incubated with each liquid salt. In conclusion, the hydrolytic activity of Lip1 is modulated by the ionic liquids BmimBF4 and BmimPF6, improving the reaction rate and the catalytic efficiency of this enzyme when BmimPF6 was used. This effect is probably due to changes in the structure of Lip1 induced by the presence of these ionic liquids, stimulating its catalytic activity.

  14. Cloning, sequencing, and expression of the cold-inducible hutU gene from the antarctic psychrotrophic bacterium Pseudomonas syringae.

    PubMed

    Janiyani, Kamala L; Ray, M K

    2002-01-01

    A promoter-fusion study with a Tn 5-based promoter probe vector had earlier found that the hutU gene which encodes the enzyme urocanase for the histidine utilization pathway is upregulated at a lower temperature (4 degrees C) in the Antarctic psychrotrophic bacterium Pseudomonas syringae. To examine the characteristics of the urocanase gene and its promoter elements from the psychrotroph, the complete hutU and its upstream region from P. syringae were cloned, sequenced, and analyzed in the present study. Northern blot and primer extension analyses suggested that the hutU gene is inducible upon a downshift of temperature (22 to 4 degrees C) and that there is more than one transcription initiation site. One of the initiation sites was specific to the cells grown at 4 degrees C, which was different from the common initiation sites observed at both 4 and 22 degrees C. Although no typical promoter consensus sequences were observed in the flanking region of the transcription initiation sites, there was a characteristic CAAAA sequence at the -10 position of the promoters. Additionally, the location of the transcription and translation initiation sites suggested that the hutU mRNA contains a long 5'-untranslated region, a characteristic feature of many cold-inducible genes of mesophilic bacteria. A comparison of deduced amino acid sequences of urocanase from various bacteria, including the mesophilic and psychrotrophic Pseudomonas spp., suggests that there is a high degree of similarity between the enzymes. The enzyme sequence contains a signature motif (GXGX(2)GX(10)G) of the Rossmann fold for dinucleotide (NAD(+)) binding and two conserved cysteine residues in and around the active site. The psychrotrophic enzyme, however, has an extended N-terminal end.

  15. Bacillus piscis sp. nov., a novel bacterium isolated from the muscle of the antarctic fish Dissostichus mawsoni.

    PubMed

    Lee, Jae-Bong; Jeon, Seon Hwa; Choi, Seok-Gwan; Jung, Hee-Young; Kim, Myung Kyum; Srinivasan, Sathiyaraj

    2016-12-01

    In this paper, a new bacterial strain designated as 16MFT21(T) is isolated from the muscle of a fish caught in the Antarctic Ocean. Strain 16MFT21(T) is a Gram-staining-positive, catalase-oxidase-positive, rod-shaped facultative-aerobic bacterium. The phylogenetic analysis that is based on the 16S-rRNA gene sequence of strain 16MFT21(T) revealed that it belongs to the genus Bacillus in the family Bacillaceae in the class Bacilli. The highest degrees of the sequence similarity of the strain 16MFT21(T) is with Bacillus licheniformis ATCC 14580(T) (96.6%) and Bacillus sonorensis NBRC 101234(T) (96.6%). The isolate formed a pale-yellow pigment, and it grew in the presence of 0% to 10% (w/v) NaCl (optimum at 2% NaCl), a pH of 6.0 to 10.0 (optimum pH from 7.0 to 8.0), and from 4°C to 30°C (optimum at 30°C). The major polar lipids consist of diphosphatidylglycerol (DPG) and phosphatidylglycerol (PG). The predominant fatty acids are iso-C15:0, anteiso-C15:0, iso-C17:0, and anteiso-C17:0. The main respiratory quinone is menaquinone-7 (MK-7), and based on the use of the meso-diaminopimelic acid as the diagnostic diamino acid, the peptidoglycan cell-wall type is A1γ. Based on the phylogenetic, phenotypic, and chemotaxonomic data, strain 16MFT21(T) (=KCTC 18866(T) =JCM 31664(T)) for which the name Bacillus piscis sp. nov. is proposed should be classified as a new species.

  16. Polymorphobacter multimanifer gen. nov., sp. nov., a polymorphic bacterium isolated from Antarctic white rock.

    PubMed

    Fukuda, Wakao; Chino, Yohzo; Araki, Shigeo; Kondo, Yuka; Imanaka, Hiroyuki; Kanai, Tamotsu; Atomi, Haruyuki; Imanaka, Tadayuki

    2014-06-01

    A Gram-stain-negative, non-spore-forming, aerobic, oligotrophic bacterium (strain 262-7(T)) was isolated from a crack of white rock collected in the Skallen region of Antarctica. Strain 262-7(T) grew at temperatures between -4 and 30 °C, with optimal growth at 25 °C. The pH range for growth was between pH 6.0 and 9.0, with optimal growth at approximately pH 7.0. The NaCl concentration range allowing growth was between 0.0 and 1.0%, with an optimum of 0.5%. Strain 262-7(T) showed an unprecedented range of morphological diversity in response to growth conditions. Cells grown in liquid medium were circular or ovoid with smooth surfaces in the lag phase. In the exponential phase, ovoid cells with short projections were observed. Cells in the stationary phase possessed long tentacle-like projections intertwined intricately. By contrast, cells grown on agar plate medium or in liquid media containing organic compounds at low concentration exhibited short- and long-rod-shaped morphology. These projections and morphological variations clearly differ from those of previously described bacteria. Ubiquinone 10 was the major respiratory quinone. The major fatty acids were C(17 : 1)ω6c (28.2%), C(16 : 1)ω7c (22.6%), C(18 : 1)ω7c (12.9%) and C(15 : 0) 2-OH (12.3%). The G+C content of genomic DNA was 68.0 mol%. Carotenoids were detected from the cells. Comparative analyses of 16S rRNA gene sequences indicated that strain 262-7(T) belongs to the family Sphingomonadaceae, and that 262-7(T) should be distinguished from known genera in the family Sphingomonadaceae. According to the phylogenetic position, physiological characteristics and unique morphology variations, strain 262-7(T) should be classified as a representative of a novel genus of the family Sphingomonadaceae. Here, a novel genus and species with the name Polymorphobacter multimanifer gen. nov., sp. nov. is proposed (type strain 262-7(T) = JCM 18140(T) = ATCC BAA-2413(T)). The novel species was

  17. PhAP protease from Pseudoalteromonas haloplanktis TAC125: Gene cloning, recombinant production in E. coli and enzyme characterization

    NASA Astrophysics Data System (ADS)

    de Pascale, D.; Giuliani, M.; De Santi, C.; Bergamasco, N.; Amoresano, A.; Carpentieri, A.; Parrilli, E.; Tutino, M. L.

    2010-08-01

    Cold-adapted proteases have been found to be the dominant activity throughout the cold marine environment, indicating their importance in bacterial acquisition of nitrogen-rich complex organic compounds. However, few extracellular proteases from marine organisms have been characterized so far, and the mechanisms that enable their activity in situ are still largely unknown. Aside from their ecological importance and use as model enzyme for structure/function investigations, cold-active proteolytic enzymes offer great potential for biotechnological applications. Our studies on cold adapted proteases were performed on exo-enzyme produced by the Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125. By applying a proteomic approach, we identified several proteolytic activities from its culture supernatant. PhAP protease was selected for further investigations. The encoding gene was cloned and the protein was recombinantly produced in E. coli cells. The homogeneous product was biochemically characterised and it turned out that the enzyme is a Zn-dependent aminopeptidase, with an activity dependence from assay temperature typical of psychrophilic enzymes.

  18. Anti-biofilm activity of pseudoalteromonas haloplanktis tac125 against staphylococcus epidermidis biofilm: Evidence of a signal molecule involvement?

    PubMed

    Parrilli, E; Papa, R; Carillo, S; Tilotta, M; Casillo, A; Sannino, F; Cellini, A; Artini, M; Selan, L; Corsaro, M M; Tutino, M L

    2015-03-01

    Staphylococcus epidermidis is recognized as cause of biofilm-associated infections and interest in the development of new approaches for S. epidermidis biofilm treatment has increased. In a previous paper we reported that the supernatant of Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 presents an anti-biofilm activity against S. epidermidis and preliminary physico-chemical characterization of the supernatant suggested that this activity is due to a polysaccharide. In this work we further investigated the chemical nature of the anti-biofilm P. haloplanktis TAC125 molecule. The production of the molecule was evaluated in different conditions, and reported data demonstrated that it is produced in all P. haloplanktis TAC125 biofilm growth stages, also in minimal medium and at different temperatures. By using a surface coating assay, the surfactant nature of the anti-biofilm compound was excluded. Moreover, a purification procedure was set up and the analysis of an enriched fraction demonstrated that the anti-biofilm activity is not due to a polysaccharide molecule but that it is due to small hydrophobic molecules that likely work as signal. The enriched fraction was also used to evaluate the effect on S. epidermidis biofilm formation in dynamic condition by BioFlux system. © The Author(s) 2015.

  19. RecD Plays an Essential Function During Growth at Low Temperature in the Antarctic Bacterium Pseudomonas syringae Lz4W

    PubMed Central

    Regha, K.; Satapathy, Ajit K.; Ray, Malay K.

    2005-01-01

    The Antarctic psychrotrophic bacterium Pseudomonas syringae Lz4W has been used as a model system to identify genes that are required for growth at low temperature. Transposon mutagenesis was carried out to isolate mutant(s) of the bacterium that are defective for growth at 4° but normal at 22°. In one such cold-sensitive mutant (CS1), the transposon-disrupted gene was identified to be a homolog of the recD gene of several bacteria. Trans-complementation and freshly targeted gene disruption studies reconfirmed that the inactivation of the recD gene leads to a cold-sensitive phenotype. We cloned, sequenced, and analyzed ∼11.2 kbp of DNA from recD and its flanking region from the bacterium. recD was the last gene of a putative recCBD operon. The RecD ORF was 694 amino acids long and 40% identical (52% similar) to the Escherichia coli protein, and it could complement the E. coli recD mutation. The recD gene of E. coli, however, could not complement the cold-sensitive phenotype of the CS1 mutant. Interestingly, the CS1 strain showed greater sensitivity toward the DNA-damaging agents, mitomycin C and UV. The inactivation of recD in P. syringae also led to cell death and accumulation of DNA fragments of ∼25–30 kbp in size at low temperature (4°). We propose that during growth at a very low temperature the Antarctic P. syringae is subjected to DNA damage, which requires direct participation of a unique RecD function. Additional results suggest that a truncated recD encoding the N-terminal segment of (1–576) amino acids is sufficient to support growth of P. syringae at low temperature. PMID:15956672

  20. Oxygen limitation favors the production of protein with antimicrobial activity in Pseudoalteromonas sp

    PubMed Central

    López, Ruth; Monteón, Víctor; Chan, Ernesto; Montejo, Rubí; Chan, Manuel

    2012-01-01

    This study examined the effect of dissolved oxygen concentration on the production of biomass and metabolites with antimicrobial activity of Pseudoalteromonas sp cultured at 0, 150, 250, or 450 revolutions per minute (rev. min-1). Dissolved oxygen (D.O) was monitored during the fermentation process, biomass was quantified by dry weight, and antimicrobial activity was assessed using the disk diffusion method. The bacterium Pseudoalteromonas reached similar concentration of biomass under all experimental agitation conditions, whereas antimicrobial activity was detected at 0 and 150 rev. min-1 registering 0% and 12% of D.O respectively corresponding to microaerophilic conditions. Antibiotic activity was severely diminished when D.O was above 20% of saturation; this corresponded to 250 or 450 rev. min-1. SDS-PAGE electrophoresis revealed a protein with a molecular weight of approximately 80 kilodaltons (kDa) with antimicrobial activity. Pseudoalteromonas is capable of growing under oxic and microaerophilic conditions but the metabolites with antimicrobial activity are induced under microaerophilic conditions. The current opinion is that Pseudoalteromonas are aerobic organisms; we provide additional information on the amount of dissolved oxygen during the fermentation process and its effect on antimicrobial activity. PMID:24031945

  1. Psychrosinus fermentans gen. nov., sp. nov., a lactate-fermenting bacterium from near-freezing oxycline waters of a meromictic Antarctic lake.

    PubMed

    Sattley, W Matthew; Jung, Deborah O; Madigan, Michael T

    2008-10-01

    A novel, obligately anaerobic, fermentative bacterium, strain FCF9, was isolated from a 9-m water sample from permanently ice-covered, meromictic Lake Fryxell, Antarctica. A phylogenetic analysis based on 16S rRNA gene sequence identity clustered the Antarctic isolate within the Sporomusa-Pectinatus-Selenomonas phyletic group, where it was most closely related to Pelosinus fermentans (95.5% sequence identity). However, unlike species of Pelosinus, strain FCF9 was psychrophilic, with growth occurring optimally near 15 degrees C, and endospores were not produced. The metabolism of the new organism was strictly fermentative. The substrates fermented by strain FCF9 included only lactate and a few related organic acids. The major products from lactate fermentation were acetate and propionate. On the basis of phylogenetic, morphological, and physiological criteria, strain FCF9(T) is proposed as the type strain of a novel genus and species of psychrophilic-fermenting bacteria, Psychrosinus fermentans gen. nov., sp. nov.

  2. [Cloning and expression of endoglucanase of marine cold-adapted bacteria Pseudoalteromonas sp. MB-1].

    PubMed

    You, Yin-wei; Wang, Tian-hong

    2005-02-01

    The cold-adapted gram-negative rod bacterium MB-1 which could secret cellulase was screened from mud of the bottom of the Huanghai. According to the sequence of 16S rDNA, this bacterium screened was identified as one species of Pseudoalteromonas and was named as Pseudoalteromonas sp. MB-1. The gene celA encoding cold-adapted endogluanase was cloned and then jointed to pGEX-4T-1 to construct expression plasmid pGEX-celA which was expressed in E. coli BL21. Analysis to the supernatant of E. coli sonicate revealed that the concentration of GST-CelA was about 78.5 mg/L. Properties of the fusion enzyme of GST-CelA including the optimum temperature at 35 degrees C and the optimum pH about 7.2, showed that this fusion enzyme still belonged to cold-adapted enzyme and neutral enzyme. The result lays solid base for the fundamental theory and application research on cold-adapted cellulase from Pseudoalteromonas sp. MB-1.

  3. The anti-biofilm activity secreted by a marine Pseudoalteromonas strain.

    PubMed

    Klein, Géraldine L; Soum-Soutéra, Emmanuelle; Guede, Zakoua; Bazire, Alexis; Compère, Chantal; Dufour, Alain

    2011-09-01

    Bacterial biofilms occur on all submerged structures in marine environments. The authors previously reported that the marine bacterium Pseudoalteromonas sp. 3J6 secretes antibiofilm activity. Here, it was discovered that another Pseudoalteromonas sp. strain, D41, inhibited the development of strain 3J6 in mixed biofilms. Confocal laser scanning microscope observations revealed that the culture supernatant of strain D41 impaired biofilm formation of strain 3J6 and another marine bacterium. A microtiter plate assay of the antibiofilm activity was set up and validated with culture supernatants of Pseudoalteromonas sp. 3J6. This assay was used to determine the spectra of action of strains D41 and 3J6. Each culture supernatant impaired the biofilm development of 13 marine bacteria out of 18. However, differences in the spectra of action and the physical behaviours of the antibiofilm molecules suggest that the latter are not identical. They nevertheless share the originality of being devoid of antibacterial activity against planktonic bacteria.

  4. Psychrobacter proteolyticus sp. nov., a psychrotrophic, halotolerant bacterium isolated from the Antarctic krill Euphausia superba Dana, excreting a cold-adapted metalloprotease.

    PubMed

    Denner, E B; Mark, B; Busse, H J; Turkiewicz, M; Lubitz, W

    2001-04-01

    An Antarctic marine bacterium (strain 116) excreting an extracellular cold-adapted metalloprotease was subjected to a detailed polyphasic taxonomic investigation. Strain 116 was previously isolated from the stomach of a specimen of the Antarctic krill Euphasia superba Dana and tentatively characterized as Sphingomonas paucimobilis 116. The 16S rDNA sequence analysis showed that the strain is in fact related to species of the genus Psychrobacter, next to Psychrobacter glacincola (97.4% similarity). Sequence similarities between strain 116 and other Psychrobacter species ranged from 96.9% (with P. urativorans) to 95.4% (with P. immobilis). Key phenotypic characteristics as well as chemotaxonomic features of the bacterium were congruent with the description of the genus Psychrobacter i.e. cells were strictly aerobic, strongly oxidase-positive, psychrotrophic, halotolerant, gram-negative non-motile coccobacilli, with ubiquinone-8 as the main respiratory lipoquinone and 18:1 cis 9, 16:1 cis and 17:1 (omega8c being the predominant cellular fatty acids. The G+C content of the DNA was 43.6 mol%. DNA-DNA hybridization studies showed that the relatedness between strain 116 and Psychrobacter glacinola is only 62.2%. Further differences were apparent in whole-cell SDS-PAGE protein pattern, cellular fatty acid profile and in a number of physiological and biochemical characteristics as well as in enzymatic activities. Tolerance to 5% bile salts, nitrate reduction, citrate utilization, acid production from carbohydrates, alkaline phosphatase, acid phosphatase, C4 esterase, C14 lipase and valine arylamidase were found to differentiate strain 116 from Psychrobacter glacincola. On the basis of this phenotypic and molecular evidences, strain 116, previously known as Sphingomonas paucimobilis 116, was recognized as a new species of the genus Psychrobacter for which the name Psychrobacter proteolyticus is proposed. Strain 116 has been deposited in the Collection de l'Institut Pasteur

  5. Exploring the Effects of Subfreezing Temperature and Salt Concentration on Ice Growth Inhibition of Antarctic Gram-Negative Bacterium Marinomonas Primoryensis Using Coarse-Grained Simulation.

    PubMed

    Nguyen, Hung; Dac Van, Thanh; Tran, Nhut; Le, Ly

    2016-04-01

    The aim of this work is to study the freezing process of water molecules surrounding Antarctic Gram-negative bacterium Marinomonas primoryensis antifreeze protein (MpAFP) and the MpAFP interactions to the surface of ice crystals under various marine environments (at different NaCl concentrations of 0.3, 0.6, and 0.8 mol/l). Our result indicates that activating temperature region of MpAFPs reduced as NaCl concentration increased. Specifically, MpAFP was activated and functioned at 0.6 mol/l with temperatures equal or larger 278 K, and at 0.8 mol/l with temperatures equal or larger 270 K. Additionally, MpAFP was inhibited by ice crystal network from 268 to 274 K and solid-liquid hybrid from 276 to 282 K at 0.3 mol/l concentration. Our results shed lights on structural dynamics of MpAFP among different marine environments.

  6. The Stack: A New Bacterial Structure Analyzed in the Antarctic Bacterium Pseudomonas deceptionensis M1T by Transmission Electron Microscopy and Tomography

    PubMed Central

    Delgado, Lidia; Carrión, Ornella; Martínez, Gema; López-Iglesias, Carmen; Mercadé, Elena

    2013-01-01

    In recent years, improvements in transmission electron microscopy (TEM) techniques and the use of tomography have provided a more accurate view of the complexity of the ultrastructure of prokaryotic cells. Cryoimmobilization of specimens by rapid cooling followed by freeze substitution (FS) and sectioning, freeze fracture (FF) and observation of replica, or cryoelectron microscopy of vitreous sections (CEMOVIS) now allow visualization of biological samples close to their native state, enabling us to refine our knowledge of already known bacterial structures and to discover new ones. Application of these techniques to the new Antarctic cold-adapted bacterium Pseudomonasdeceptionensis M1T has demonstrated the existence of a previously undescribed cytoplasmic structure that does not correspond to known bacterial inclusion bodies or membranous formations. This structure, which we term a “stack”, was mainly visualized in slow growing cultures of P. deceptionensis M1T and can be described as a set of stacked membranous discs usually arranged perpendicularly to the cell membrane, but not continuous with it, and found in variable number in different locations within the cell. Regardless of their position, stacks were mostly observed very close to DNA fibers. Stacks are not exclusive to P. deceptionensis M1T and were also visualized in slow-growing cultures of other bacteria. This new structure deserves further study using cryoelectron tomography to refine its configuration and to establish whether its function could be related to chromosome dynamics. PMID:24039905

  7. Identification of regulatory sequences and expression analysis of OmpR gene under different stress conditions in the antarctic bacterium Psychrobacter sp. G.

    PubMed

    Song, Weizhi; Lin, Xuezheng; Che, Shuai

    2013-03-01

    An OmpR gene, named OmpR503, was cloned from the Antarctic psychrotrophic bacterium Psychrobacter sp. G according to its genomic draft. The deduced amino acid sequences of OmpR503 were highly conserved with other known protein members of OmpR family. qRT-PCR analysis showed that the expression of OmpR503 gene was significantly enhanced by high salinity (90, 120). The expression of OmpR503 gene was also significantly increased at low temperature (0, 10 °C), whereas depressed at high temperature (30 °C). When the strain was subjected to combined stress (0 °C with a salinity of 90), the expression of OmpR503 gene was increased significantly, which was up to 3.0-fold. In Antarctica, freezing tolerance of psychrotrophic bacteria is often accompanied by tolerance to osmotic stress caused by a lack of free water, thus the cold inducibility of OmpR503 gene might help the strain adapt to the harsh environment more efficiently.

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

    PubMed Central

    Li, Jiang; Hu, Qiushi; Li, Yuquan; Xu, Yuan

    2015-01-01

    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. PMID:26413048

  9. Kocuria polaris sp. nov., an orange-pigmented psychrophilic bacterium isolated from an Antarctic cyanobacterial mat sample.

    PubMed

    Reddy, Gundlapally S N; Prakash, Jogadhenu S S; Prabahar, Vadivel; Matsumoto, Genki I; Stackebrandt, Erko; Shivaji, Sisinthy

    2003-01-01

    Strain CMS 76orT, an orange-pigmented bacterium, was isolated from a cyanobacterial mat sample from a pond located in McMurdo Dry Valley, Antarctica. On the basis of chemotaxonomic and phylogenetic properties, strain CMS 76orT was identified as a member of the genus Kocuria. It exhibited a 16S rDNA similarity of 99.8% and DNA-DNA similarity of 71% with Kocuria rosea (ATCC 186T). Phenotypic traits confirmed that strain CMS 78orT and K. rosea were well differentiated. Furthermore, strain CMS 76orT could be differentiated from the other reported species of Kocuria, namely Kocuria kristinae (ATCC 27570T), Kocuria varians (ATCC 15306T), Kocuria rhizophila (DSM 11926T) and Kocuria palustris (DSM 11025T), on the basis of a number of phenotypic features. Therefore, it is proposed that strain CMS 76orT (= MTCC 3702T = DSM 14382T) be assigned to a novel species of the genus Kocuria, as Kocuria polaris.

  10. Structure-based characterization and antifreeze properties of a hyperactive ice-binding protein from the Antarctic bacterium Flavobacterium frigoris PS1.

    PubMed

    Do, Hackwon; Kim, Soon-Jong; Kim, Hak Jun; Lee, Jun Hyuck

    2014-04-01

    Ice-binding proteins (IBPs) inhibit ice growth through direct interaction with ice crystals to permit the survival of polar organisms in extremely cold environments. FfIBP is an ice-binding protein encoded by the Antarctic bacterium Flavobacterium frigoris PS1. The X-ray crystal structure of FfIBP was determined to 2.1 Å resolution to gain insight into its ice-binding mechanism. The refined structure of FfIBP shows an intramolecular disulfide bond, and analytical ultracentrifugation and analytical size-exclusion chromatography show that it behaves as a monomer in solution. Sequence alignments and structural comparisons of IBPs allowed two groups of IBPs to be defined, depending on sequence differences between the α2 and α4 loop regions and the presence of the disulfide bond. Although FfIBP closely resembles Leucosporidium (recently re-classified as Glaciozyma) IBP (LeIBP) in its amino-acid sequence, the thermal hysteresis (TH) activity of FfIBP appears to be tenfold higher than that of LeIBP. A comparison of the FfIBP and LeIBP structures reveals that FfIBP has different ice-binding residues as well as a greater surface area in the ice-binding site. Notably, the ice-binding site of FfIBP is composed of a T-A/G-X-T/N motif, which is similar to the ice-binding residues of hyperactive antifreeze proteins. Thus, it is proposed that the difference in TH activity between FfIBP and LeIBP may arise from the amino-acid composition of the ice-binding site, which correlates with differences in affinity and surface complementarity to the ice crystal. In conclusion, this study provides a molecular basis for understanding the antifreeze mechanism of FfIBP and provides new insights into the reasons for the higher TH activity of FfIBP compared with LeIBP.

  11. Hyperactive antifreeze protein from an Antarctic sea ice bacterium Colwellia sp. has a compound ice-binding site without repetitive sequences.

    PubMed

    Hanada, Yuichi; Nishimiya, Yoshiyuki; Miura, Ai; Tsuda, Sakae; Kondo, Hidemasa

    2014-08-01

    Antifreeze proteins (AFPs) are structurally diverse macromolecules that bind to ice crystals and inhibit their growth to protect the organism from injuries caused by freezing. An AFP identified from the Antarctic bacterium Colwellia sp. strain SLW05 (ColAFP) is homologous to AFPs from a wide variety of psychrophilic microorganisms. To understand the antifreeze function of ColAFP, we have characterized its antifreeze activity and determined the crystal structure of this protein. The recombinant ColAFP exhibited thermal hysteresis activity of approximately 4 °C at a concentration of 0.14 mm, and induced rapid growth of ice crystals in the hexagonal direction. Fluorescence-based ice plane affinity analysis showed that ColAFP binds to multiple planes of ice, including the basal plane. These observations show that ColAFP is a hyperactive AFP. The crystal structure of ColAFP determined at 1.6 Å resolution revealed an irregular β-helical structure, similar to known homologs. Mutational and molecular docking studies showed that ColAFP binds to ice through a compound ice-binding site (IBS) located at a flat surface of the β-helix and the adjoining loop region. The IBS of ColAFP lacks the repetitive sequences that are characteristic of hyperactive AFPs. These results suggest that ColAFP exerts antifreeze activity through a compound IBS that differs from the characteristic IBSs shared by other hyperactive AFPs. This study demonstrates a novel method for protection from freezing by AFPs in psychrophilic microorganisms. Structural data for ColAFP have been submitted to the Protein Data Bank (PDB) under accession number 3WP9. © 2014 FEBS.

  12. Structure of EstA esterase from psychrotrophic Pseudoalteromonas sp. 643A covalently inhibited by monoethylphosphonate

    SciTech Connect

    Brzuszkiewicz, Anna; Nowak, Elzbieta; Dauter, Zbigniew; Dauter, Miroslawa; Cieslinski, Hubert; Dlugolecka, Anna; Kur, Józef

    2010-10-28

    The crystal structure of the esterase EstA from the cold-adapted bacterium Pseudoalteromonas sp. 643A was determined in a covalently inhibited form at a resolution of 1.35 {angstrom}. The enzyme has a typical SGNH hydrolase structure consisting of a single domain containing a five-stranded {beta}-sheet, with three helices at the convex side and two helices at the concave side of the sheet, and is ornamented with a couple of very short helices at the domain edges. The active site is located in a groove and contains the classic catalytic triad of Ser, His and Asp. In the structure of the crystal soaked in diethyl p-nitrophenyl phosphate (DNP), the catalytic serine is covalently connected to a phosphonate moiety that clearly has only one ethyl group. This is the only example in the Protein Data Bank of a DNP-inhibited enzyme with covalently bound monoethylphosphate.

  13. Spotlight on Antimicrobial Metabolites from the Marine Bacteria Pseudoalteromonas: Chemodiversity and Ecological Significance

    PubMed Central

    Offret, Clément; Desriac, Florie; Le Chevalier, Patrick; Mounier, Jérôme; Jégou, Camille; Fleury, Yannick

    2016-01-01

    This review is dedicated to the antimicrobial metabolite-producing Pseudoalteromonas strains. The genus Pseudoalteromonas hosts 41 species, among which 16 are antimicrobial metabolite producers. To date, a total of 69 antimicrobial compounds belonging to 18 different families have been documented. They are classified into alkaloids, polyketides, and peptides. Finally as Pseudoalteromonas strains are frequently associated with macroorganisms, we can discuss the ecological significance of antimicrobial Pseudoalteromonas as part of the resident microbiota. PMID:27399731

  14. Genome sequences of six Pseudoalteromonas strains isolated from Arctic sea ice.

    PubMed

    Bian, Fei; Xie, Bin-Bin; Qin, Qi-Long; Shu, Yan-Li; Zhang, Xi-Ying; Yu, Yong; Chen, Bo; Chen, Xiu-Lan; Zhou, Bai-Cheng; Zhang, Yu-Zhong

    2012-02-01

    Yu et al. (Polar Biol. 32:1539-1547, 2009) isolated 199 Pseudoalteromonas strains from Arctic sea ice. We sequenced the genomes of six of these strains, which are affiliated to different Pseudoalteromonas species based on 16S rRNA gene sequences, facilitating the study of physiology and adaptation of Arctic sea ice Pseudoalteromonas strains.

  15. Algicidal Effects of a Novel Marine Pseudoalteromonas Isolate (Class Proteobacteria, Gamma Subdivision) on Harmful Algal Bloom Species of the Genera Chattonella, Gymnodinium, and Heterosigma

    PubMed Central

    Lovejoy, Connie; Bowman, John P.; Hallegraeff, Gustaaf M.

    1998-01-01

    During a bacterial survey of the Huon Estuary in southern Tasmania, Australia, we isolated a yellow-pigmented Pseudoalteromonas strain (class Proteobacteria, gamma subdivision), designated strain Y, that had potent algicidal effects on harmful algal bloom species. This organism was identified by 16S rRNA sequencing as a strain with close affinities to Pseudoalteromonas peptidysin. This bacterium caused rapid cell lysis and death (within 3 h) of gymnodinoids (including Gymnodinium catenatum) and raphidophytes (Chattonella marina and Heterosigma akashiwo). It caused ecdysis of armored dinoflagellates (e.g., Alexandrium catenella, Alexandrium minutum, and Prorocentrum mexicanum), but the algal cultures then recovered over the subsequent 24 h. Strain Y had no effect on a cryptomonad (Chroomonas sp.), a diatom (Skeletonema sp.), a cyanobacterium (Oscillatoria sp.), and two aplastidic protozoans. The algicidal principle of strain Y was excreted into the seawater medium and lost its efficacy after heating. Another common bacterial species, Pseudoalteromonas carrageenovora, was isolated at the same time and did not have these algicidal effects. The minimum concentrations of strain Y required to kill G. catenatum were higher than the mean concentrations found in nature under nonbloom conditions. However, the new bacterium showed a chemotactic, swarming behavior that resulted in localized high concentrations around target organisms. These observations imply that certain bacteria could play an important role in regulating the onset and development of harmful algal blooms. PMID:9687434

  16. Isolation and characterization of Pseudoalteromonas sp. from fermented Korean food, as an antagonist to Vibrio harveyi.

    PubMed

    Morya, V K; Choi, Wooyoung; Kim, Eun-Ki

    2014-02-01

    The microbial intervention for sustainable management of aquaculture, especially use of probiotics, is one of the most popular and practical approaches towards controlling pathogens. Vibrio harveyi is a well-known pathogenic bacterium, which is associated to a huge economic loss in the aquaculture system by causing vibriosis. The present study is crafted for screening and characterization of anti-Vibrio strains, which were isolated from various traditional fermented Korean foods. A total of 196 strains have been isolated from soybean paste (78 strains), red chili paste (49 strains), soy sauce (18 strains), jeotgal-a salted fish (34 strains), and the gazami crab-Portunus trituberculatus (17 strains). Fifteen strains showed an inhibitory effect on the growth of V. harveyi when subjected to coculture condition. Among the strains isolated, one has been identified as a significant anti-Vibrio strain. Further biochemical characterization and 16S rDNA sequencing revealed it as Pseudoalteromonas aliena, which had been deposited at the Korean Culture Center of Microorganisms (KCCM), Korea and designated as KCCM 11207P. The culture supernatants did not have any antimicrobial properties either in pure or in coculture condition. The culture supernatant was not toxic when supplemented to the swimming crab, Zoea, and Artemia larvae in aquaculture system. The results were very encouraging and showed a significant reduction in accumulated mortality. Here, we reported that pathogenic vibriosis can be controlled by Pseudoalteromonas sp. under in vitro and in vivo conditions. The results indicated that the biotic treatment offers a promising alternative to the use of antibiotics in crab aquaculture.

  17. Solution and crystal structure of BA42, a protein from the Antarctic bacterium Bizionia argentinensis comprised of a stand-alone TPM domain.

    PubMed

    Aran, Martin; Smal, Clara; Pellizza, Leonardo; Gallo, Mariana; Otero, Lisandro H; Klinke, Sebastián; Goldbaum, Fernando A; Ithurralde, Esteban R; Bercovich, Andrés; Mac Cormack, Walter P; Turjanski, Adrián G; Cicero, Daniel O

    2014-11-01

    The structure of the BA42 protein belonging to the Antarctic flavobacterium Bizionia argentinensis was determined by nuclear magnetic resonance and X-ray crystallography. This is the first structure of a member of the PF04536 family comprised of a stand-alone TPM domain. The structure reveals a new topological variant of the four β-strands constituting the central β-sheet of the αβα architecture and a double metal binding site stabilizing a pair of crossing loops, not observed in previous structures of proteins belonging to this family. BA42 shows differences in structure and dynamics in the presence or absence of bound metals. The affinity for divalent metal ions is close to that observed in proteins that modulate their activity as a function of metal concentration, anticipating a possible role for BA42. © 2014 Wiley Periodicals, Inc.

  18. Antarctic bacterial haemoglobin and its role in the protection against nitrogen reactive species.

    PubMed

    Coppola, Daniela; Giordano, Daniela; Tinajero-Trejo, Mariana; di Prisco, Guido; Ascenzi, Paolo; Poole, Robert K; Verde, Cinzia

    2013-09-01

    In a cold and oxygen-rich environment such as Antarctica, mechanisms for the defence against reactive oxygen and nitrogen species are needed and represent important components in the evolutionary adaptations. In the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125, the presence of multiple genes encoding 2/2 haemoglobins and a flavohaemoglobin strongly suggests that these proteins fulfil important physiological roles, perhaps associated to the peculiar features of the Antarctic habitat. In this work, the putative role of Ph-2/2HbO, encoded by the PSHAa0030 gene, was investigated by in vivo and in vitro experiments in order to highlight its involvement in NO detoxification mechanisms. The PSHAa0030 gene was cloned and then over-expressed in a flavohaemoglobin-deficient mutant of Escherichia coli, unable to metabolise NO, and the resulting strain was studied analysing its growth properties and oxygen uptake in the presence of NO. We here demonstrate that Ph-2/2HbO protects growth and cellular respiration of the heterologous host from the toxic effect of NO-donors. Unlike in Mycobacterium tuberculosis 2/2 HbN, the deletion of the N-terminal extension of Ph-2/2HbO does not seem to reduce the NO scavenging activity, showing that the N-terminal extension is not a requirement for efficient NO detoxification. Moreover, the ferric form of Ph-2/2HbO was shown to catalyse peroxynitrite isomerisation in vitro, confirming its potential role in the scavenging of reactive nitrogen species. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.

  19. Exploring Regulation Genes Involved in the Expression of L-Amino Acid Oxidase in Pseudoalteromonas sp. Rf-1

    PubMed Central

    Wang, Ju; Lin, Jianxun; Zhao, Minyan

    2015-01-01

    Bacterial L-amino acid oxidase (LAAO) is believed to play important biological and ecological roles in marine niches, thus attracting increasing attention to understand the regulation mechanisms underlying its production. In this study, we investigated genes involved in LAAO production in marine bacterium Pseudoalteromonas sp. Rf-1 using transposon mutagenesis. Of more than 4,000 mutants screened, 15 mutants showed significant changes in LAAO activity. Desired transposon insertion was confirmed in 12 mutants, in which disrupted genes and corresponding functionswere identified. Analysis of LAAO activity and lao gene expression revealed that GntR family transcriptional regulator, methylase, non-ribosomal peptide synthetase, TonB-dependent heme-receptor family, Na+/H+ antiporter and related arsenite permease, N-acetyltransferase GCN5, Ketol-acid reductoisomerase and SAM-dependent methytransferase, and their coding genes may be involved in either upregulation or downregulation pathway at transcriptional, posttranscriptional, translational and/or posttranslational level. The nhaD and sdmT genes were separately complemented into the corresponding mutants with abolished LAAO-activity. The complementation of either gene can restore LAAO activity and lao gene expression, demonstrating their regulatory role in LAAO biosynthesis. This study provides, for the first time, insights into the molecular mechanisms regulating LAAO production in Pseudoalteromonas sp. Rf-1, which is important to better understand biological and ecological roles of LAAO. PMID:25815733

  20. Purine nucleoside phosphorylase from Pseudoalteromonas sp. Bsi590: molecular cloning, gene expression and characterization of the recombinant protein.

    PubMed

    Li, Xiaohui; Jiang, Xinyin; Li, Huirong; Ren, Daming

    2008-05-01

    The gene encoding purine nucleoside phosphorylase (PNP) from the cold-adapted marine bacterium Pseudoalteromonas sp. Bsi590 was identified, cloned and expressed in Escherichia coli. The gene encodes a polypeptide of 233 amino acids with a calculated molecular weight of 25,018 Da. Pseudoalteromonas sp. Bsi590 PNP (PiPNP) shares 60% amino sequence identity and conservation of amino acid residues involved in catalysis with mesophilic Escherichia coli deoD-encoded purine nucleoside phosphorylase (EcPNP). N-terminal his-tagged PiPNP and EcPNP were purified to apparent homogeneity using Ni2+-chelating column. Compared with EcPNP, PiPNP possessed a lower temperature optimum and thermal stability. As for PNP enzymes in general, PiPNP and EcPNP displayed complicated kinetic properties; PiPNP possessed higher Km and catalytic efficiency (kcat/Km) compared to EcPNP at 37 degrees C. Substrate specificity results showed PiPNP catalyzed the phosphorolytic cleavage of 6-oxopurine and 6-aminopurine nucleosides (or 2-deoxynucleosides), and to a lesser extent purine arabinosides. PiPNP showed a better activity with inosine while no activity toward pyrimidine nucleosides. The protein conformation was analyzed by temperature perturbation difference spectrum. Results showed that PiPNP had lower conformation transition point temperature than EcPNP; phosphate buffer and KCl had significant influence on PiPNP protein conformation stability and thermostability.

  1. Proteomic and transcriptomic investigations on cold-responsive properties of the psychrophilic Antarctic bacterium Psychrobacter sp. PAMC 21119 at subzero temperatures.

    PubMed

    Koh, Hye Yeon; Park, Hyun; Lee, Jun Hyuck; Han, Se Jong; Sohn, Young Chang; Lee, Sung Gu

    2017-02-01

    Psychrobacter sp. PAMC 21119, isolated from Antarctic permafrost soil, grows and proliferates at subzero temperatures. However, its major mechanism of cold adaptation regulation remains poorly understood. We investigated the transcriptomic and proteomic responses of this species to cold temperatures by comparing profiles at -5°C and 20°C to understand how extreme microorganisms survive under subzero conditions. We found a total of 2,906 transcripts and 584 differentially expressed genes (≥ twofold, P <0.005) by RNA-seq. Genes for translation, ribosomal structure and biogenesis were upregulated, and lipid transport and metabolism was downregulated at low temperatures. A total of 60 protein spots (≥ 1.8 fold, P < 0.005) showed differential expression on two-dimensional gel electrophoresis and the proteins were identified by mass spectrometry. The most prominent upregulated proteins in response to cold were involved in metabolite transport, protein folding and membrane fluidity. Proteins involved in energy production and conversion, and heme protein synthesis were downregulated. Moreover, isoform exchange of cold-shock proteins was detected at both temperatures. Interestingly, pathways for acetyl-CoA metabolism, putrescine synthesis and amino acid metabolism were upregulated. This study highlights some of the strategies and different physiological states that Psychrobacter sp. PAMC 21119 has developed to adapt to the cold environment in Antarctica.

  2. Crystal structure of the inactive state of the receiver domain of Spo0A from Paenisporosarcina sp. TG-14, a psychrophilic bacterium isolated from an Antarctic glacier.

    PubMed

    Lee, Chang Woo; Park, Sun-Ha; Lee, Sung Gu; Shin, Seung Chul; Han, Se Jong; Kim, Han-Woo; Park, Hyun Ho; Kim, Sunghwan; Kim, Hak Jun; Park, Hyun; Park, HaJeung; Lee, Jun Hyuck

    2017-03-09

    The two-component phosphorelay system is the most prevalent mechanism for sensing and transducing environmental signals in bacteria. Spore formation, which relies on the two-component phosphorelay system, enables the longterm survival of the glacial bacterium Paenisporosarcina sp. TG-14 in the extreme cold environment. Spo0A is a key response regulator of the phosphorelay system in the early stage of spore formation. The protein is composed of a regulatory N-terminal phospho-receiver domain and a DNAbinding C-terminal activator domain. We solved the threedimensional structure of the unphosphorylated (inactive) form of the receiver domain of Spo0A (PaSpo0A-R) from Paenisporosarcina sp. TG-14. A structural comparison with phosphorylated (active form) Spo0A from Bacillus stearothermophilus (BsSpo0A) showed minor notable differences. A molecular dynamics study of a model of the active form and the crystal structures revealed significant differences in the α4 helix and the preceding loop region where phosphorylation occurs. Although an oligomerization study of PaSpo0A-R by analytical ultracentrifugation (AUC) has shown that the protein is in a monomeric state in solution, both crosslinking and crystal-packing analyses indicate the possibility of weak dimer formation by a previously undocumented mechanism. Collectively, these observations provide insight into the mechanism of phosphorylation-dependent activation unique to Spo0A.

  3. Genome Sequences of Pseudoalteromonas Strains ATCC BAA-314, ATCC 70018, and ATCC 70019.

    PubMed

    Givan, Scott A; Zhou, Ming-Yi; Bromert, Karen; Bivens, Nathan; Chapman, Linda Fleet

    2015-05-07

    The assembly and annotation of the draft genome sequences for Pseudoalteromonas strains ATCC BAA314, ATCC 700518, and ATCC 700519 reveal candidates for promoting symbiosis between Pseudoalteromonas strains and eukaryotes. Groups of genes generally associated with virulence are present in all three strains, suggesting that these bacteria may be pathogenic under specific circumstances.

  4. Inhibition of Fungal Colonization by Pseudoalteromonas tunicata Provides a Competitive Advantage during Surface Colonization†

    PubMed Central

    Franks, A.; Egan, S.; Holmström, C.; James, S.; Lappin-Scott, H.; Kjelleberg, S.

    2006-01-01

    The marine epiphytic bacterium Pseudoalteromonas tunicata produces a range of extracellular secondary metabolites that inhibit an array of common fouling organisms, including fungi. In this study, we test the hypothesis that the ability to inhibit fungi provides P. tunicata with an advantage during colonization of a surface. Studies on a transposon-generated antifungal-deficient mutant of P. tunicata, FM3, indicated that a long-chain fatty acid-coenzyme A ligase is involved in the production of a broad-range antifungal compound by P. tunicata. Flow cell experiments demonstrated that production of an antifungal compound provided P. tunicata with a competitive advantage against a marine yeast isolate during surface colonization. This compound enabled P. tunicata to disrupt an already established fungal biofilm by decreasing the number of yeast cells attached to the surface by 66% ± 9%. For in vivo experiments, the wild-type and FM3 strains of P. tunicata were used to inoculate the surface of the green alga Ulva australis. Double-gradient denaturing gradient gel electrophoresis analysis revealed that after 48 h, the wild-type P. tunicata had outcompeted the surface-associated fungal community, whereas the antifungal-deficient mutant had no effect on the fungal community. Our data suggest that P. tunicata is an effective competitor against fungal surface communities in the marine environment. PMID:16957232

  5. Correlation between pigmentation and larval settlement deterrence by Pseudoalteromonas sp. sf57.

    PubMed

    Huang, Yi-Li; Li, Mu; Yu, Zhiliang; Qian, Pei-Yuan

    2011-03-01

    The red-pigmented marine bacterium Pseudoalteromonas sp. sf57 forms a biofilm that deters larval settlement of the tube-building polychaete Hydroides elegans. To investigate the correlation between pigmentation and larval settlement deterrence, mutants of sf57 with deficient or altered pigmentation were generated by transposon mutagenesis. Five groups of pigmented mutants were obtained, viz. white, yellow, pink, dark red, and white-to-red. The white mutant WM1, which exhibited a substantial increase in bacterial density in the biofilm, became inductive to larval settlement. The other mutants that showed a lesser increase in bacterial density in their biofilms either retained their deterrence or induced higher larval settlement rates, but did not become inductive strains. Analysis of the disrupted genes in these mutants suggests that the type II secretion pathway, the LysR transcriptional regulator, NAD(P)-binding proteins, exonuclease, pyruvate metabolism, flagella assembly, and cell membrane processes may play a role in the regulation of pigmentation in sf57.

  6. Inhibition of fungal colonization by Pseudoalteromonas tunicata provides a competitive advantage during surface colonization.

    PubMed

    Franks, A; Egan, S; Holmström, C; James, S; Lappin-Scott, H; Kjelleberg, S

    2006-09-01

    The marine epiphytic bacterium Pseudoalteromonas tunicata produces a range of extracellular secondary metabolites that inhibit an array of common fouling organisms, including fungi. In this study, we test the hypothesis that the ability to inhibit fungi provides P. tunicata with an advantage during colonization of a surface. Studies on a transposon-generated antifungal-deficient mutant of P. tunicata, FM3, indicated that a long-chain fatty acid-coenzyme A ligase is involved in the production of a broad-range antifungal compound by P. tunicata. Flow cell experiments demonstrated that production of an antifungal compound provided P. tunicata with a competitive advantage against a marine yeast isolate during surface colonization. This compound enabled P. tunicata to disrupt an already established fungal biofilm by decreasing the number of yeast cells attached to the surface by 66% +/- 9%. For in vivo experiments, the wild-type and FM3 strains of P. tunicata were used to inoculate the surface of the green alga Ulva australis. Double-gradient denaturing gradient gel electrophoresis analysis revealed that after 48 h, the wild-type P. tunicata had outcompeted the surface-associated fungal community, whereas the antifungal-deficient mutant had no effect on the fungal community. Our data suggest that P. tunicata is an effective competitor against fungal surface communities in the marine environment.

  7. Ecological Advantages of Autolysis during the Development and Dispersal of Pseudoalteromonas tunicata Biofilms

    PubMed Central

    Mai-Prochnow, Anne; Webb, Jeremy S.; Ferrari, Belinda C.; Kjelleberg, Staffan

    2006-01-01

    In the ubiquitous marine bacterium Pseudoalteromonas tunicata, subpopulations of cells are killed by the production of an autocidal protein, AlpP, during biofilm development. Our data demonstrate an involvement of this process in two parameters, dispersal and phenotypic diversification, which are of importance for the ecology of this organism and for its survival within the environment. Cell death in P. tunicata wild-type biofilms led to a major reproducible dispersal event after 192 h of biofilm development. The dispersal was not observed with a ΔAlpP mutant strain. Using flow cytometry and the fluorescent dye DiBAC4(3), we also show that P. tunicata wild-type cells that disperse from biofilms have enhanced metabolic activity compared to those cells that disperse from ΔAlpP mutant biofilms, possibly due to nutrients released from dead cells. Furthermore, we report that there was considerable phenotypic variation among cells dispersing from wild-type biofilms but not from the ΔAlpP mutant. Wild-type cells that dispersed from biofilms showed significantly increased variations in growth, motility, and biofilm formation, which may be important for successful colonization of new surfaces. These findings suggest for the first time that the autocidal events mediated by an antibacterial protein can confer ecological advantages to the species by generating a metabolically active and phenotypically diverse subpopulation of dispersal cells. PMID:16885293

  8. Genome analysis of Pseudoalteromonas flavipulchra JG1 reveals various survival advantages in marine environment

    PubMed Central

    2013-01-01

    Background Competition between bacteria for habitat and resources is very common in the natural environment and is considered to be a selective force for survival. Many strains of the genus Pseudoalteromonas were confirmed to produce bioactive compounds that provide those advantages over their competitors. In our previous study, P. flavipulchra JG1 was found to synthesize a Pseudoalteromonas flavipulchra antibacterial Protein (PfaP) with L-amino acid oxidase activity and five small chemical compounds, which were the main competitive agents of the strain. In addition, the genome of this bacterium has been previously sequenced as Whole Genome Shotgun project (PMID: 22740664). In this study, more extensive genomic analysis was performed to identify specific genes or gene clusters which related to its competitive feature, and further experiments were carried out to confirm the physiological roles of these genes when competing with other microorganisms in marine environment. Results The antibacterial protein PfaP may also participate in the biosynthesis of 6-bromoindolyl-3-acetic acid, indicating a synergistic effect between the antibacterial macromolecule and small molecules. Chitinases and quorum quenching enzymes present in P. flavipulchra, which coincide with great chitinase and acyl homoserine lactones degrading activities of strain JG1, suggest other potential mechanisms contribute to antibacterial/antifungal activities. Moreover, movability and rapid response mechanisms to phosphorus starvation and other stresses, such as antibiotic, oxidative and heavy metal stress, enable JG1 to adapt to deleterious, fluctuating and oligotrophic marine environments. Conclusions The genome of P. flavipulchra JG1 exhibits significant genetic advantages against other microorganisms, encoding antimicrobial agents as well as abilities to adapt to various adverse environments. Genes involved in synthesis of various antimicrobial substances enriches the antagonistic mechanisms of P

  9. Complete genome sequence of Pseudoalteromononas piscicida strain DE2-B, a bacterium with broad inhibitory activity toward human and fish pathogens

    USDA-ARS?s Scientific Manuscript database

    Pseudoalteromonas piscicida strain DE2-B is a halophilic bacterium which has broad inhibitory activity toward vibrios and other human and fish pathogens. We report the first closed genome sequence for this species which consists of two chromosomes (4,128,210 and 1,188,838 bp). Annotation revealed ...

  10. Metalloid reducing bacteria isolated from deep ocean hydrothermal vents of the Juan de Fuca Ridge, Pseudoalteromonas telluritireducens sp. nov. and Pseudoalteromonas spiralis sp. nov.

    PubMed

    Rathgeber, Christopher; Yurkova, Natalia; Stackebrandt, Erko; Schumann, Peter; Humphrey, Elaine; Beatty, J Thomas; Yurkov, Vladimir

    2006-11-01

    Five strains of Gram-negative, rod, curved rod and spiral-shaped bacteria were isolated from the vicinity of deep ocean hydrothermal vents along the Main Endeavour Segment of the Juan de Fuca Ridge in the Pacific Ocean. All strains showed remarkable resistance to high levels of toxic metalloid oxyanions, and were capable of reducing the oxyanions tellurite and selenite to their less toxic elemental forms. Phylogenetic analysis of four strains identified these isolates as close relatives of the genus Pseudoalteromonas within the class Gammaproteobacteria. Pseudoalteromonas agarivorans was the closest relative of strains Te-1-1 and Se-1-2-redT, with, respectively, 99.5 and 99.8% 16S rDNA sequence similarity. Strain Te-2-2T was most closely related to Pseudoalteromonas paragorgicola, with 99.8% 16S rDNA sequence similarity. The DNA G+C base composition was 39.6 to 41.8 mol%, in agreement with other members of the genus Pseudoalteromonas. However, the isolates showed important morphological and physiological differences from previously described species of this genus, with one group forming rod-shaped bacteria typical of Pseudoalteromonas and the other forming vibrioid- to spiral-shaped cells. Based on these differences, and on phylogenetic data, we propose the creation of the new species Pseudoalteromonas telluritireducens sp. nov., with strain Se-1-2-redT (DSMZ = 16098T = VKM B-2382T) as the type strain, and Pseudoalteromonas spiralis sp. nov., with strain Te-2-2T (DSMZ = 16099T = VKM B-2383T) as the type strain.

  11. Influence of production process design on inclusion bodies protein: the case of an Antarctic flavohemoglobin

    PubMed Central

    2010-01-01

    Background Protein over-production in Escherichia coli often results in formation of inclusion bodies (IBs). Some recent reports have shown that the aggregation into IBs does not necessarily mean that the target protein is inactivated and that IBs may contain a high proportion of correctly folded protein. This proportion is variable depending on the protein itself, the genetic background of the producing cells and the expression temperature. In this paper we have evaluated the influence of other production process parameters on the quality of an inclusion bodies protein. Results The present paper describes the recombinant production in Escherichia coli of the flavohemoglobin from the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125. Flavohemoglobins are multidomain proteins requiring FAD and heme cofactors. The production was carried out in several different experimental setups differing in bioreactor geometry, oxygen supply and the presence of a nitrosating compound. In all production processes, the recombinant protein accumulates in IBs, from which it was solubilized in non-denaturing conditions. Comparing structural properties of the solubilized flavohemoglobins, i.e. deriving from the different process designs, our data demonstrated that the protein preparations differ significantly in the presence of cofactors (heme and FAD) and as far as their secondary and tertiary structure content is concerned. Conclusions Data reported in this paper demonstrate that other production process parameters, besides growth temperature, can influence the structure of a recombinant product that accumulates in IBs. To the best of our knowledge, this is the first reported example in which the structural properties of a protein solubilized from inclusion bodies have been correlated to the production process design. PMID:20334669

  12. Mechanisms for pseudoalteromonas piscicida-induced killing of vibrios and other bacterial pathogens

    USDA-ARS?s Scientific Manuscript database

    Pseudoalteromonas piscicida is a Gram-negative gammaproteobacterium found in the marine environment. Three strains of pigmented P. piscicida were isolated from seawater and partially characterized by inhibition studies, electron microscopy, and analysis for proteolytic enzymes. Growth inhibition and...

  13. Biotechnological Potential of Cold Adapted Pseudoalteromonas spp. Isolated from 'Deep Sea' Sponges.

    PubMed

    Borchert, Erik; Knobloch, Stephen; Dwyer, Emilie; Flynn, Sinéad; Jackson, Stephen A; Jóhannsson, Ragnar; Marteinsson, Viggó T; O'Gara, Fergal; Dobson, Alan D W

    2017-06-19

    The marine genus Pseudoalteromonas is known for its versatile biotechnological potential with respect to the production of antimicrobials and enzymes of industrial interest. We have sequenced the genomes of three Pseudoalteromonas sp. strains isolated from different deep sea sponges on the Illumina MiSeq platform. The isolates have been screened for various industrially important enzymes and comparative genomics has been applied to investigate potential relationships between the isolates and their host organisms, while comparing them to free-living Pseudoalteromonas spp. from shallow and deep sea environments. The genomes of the sponge associated Pseudoalteromonas strains contained much lower levels of potential eukaryotic-like proteins which are known to be enriched in symbiotic sponge associated microorganisms, than might be expected for true sponge symbionts. While all the Pseudoalteromonas shared a large distinct subset of genes, nonetheless the number of unique and accessory genes is quite large and defines the pan-genome as open. Enzymatic screens indicate that a vast array of enzyme activities is expressed by the isolates, including β-galactosidase, β-glucosidase, and protease activities. A β-glucosidase gene from one of the Pseudoalteromonas isolates, strain EB27 was heterologously expressed in Escherichia coli and, following biochemical characterization, the recombinant enzyme was found to be cold-adapted, thermolabile, halotolerant, and alkaline active.

  14. Biotechnological Potential of Cold Adapted Pseudoalteromonas spp. Isolated from ‘Deep Sea’ Sponges

    PubMed Central

    Borchert, Erik; Knobloch, Stephen; Dwyer, Emilie; Flynn, Sinéad; Jackson, Stephen A.; Jóhannsson, Ragnar; Marteinsson, Viggó T.; O’Gara, Fergal; Dobson, Alan D. W.

    2017-01-01

    The marine genus Pseudoalteromonas is known for its versatile biotechnological potential with respect to the production of antimicrobials and enzymes of industrial interest. We have sequenced the genomes of three Pseudoalteromonas sp. strains isolated from different deep sea sponges on the Illumina MiSeq platform. The isolates have been screened for various industrially important enzymes and comparative genomics has been applied to investigate potential relationships between the isolates and their host organisms, while comparing them to free-living Pseudoalteromonas spp. from shallow and deep sea environments. The genomes of the sponge associated Pseudoalteromonas strains contained much lower levels of potential eukaryotic-like proteins which are known to be enriched in symbiotic sponge associated microorganisms, than might be expected for true sponge symbionts. While all the Pseudoalteromonas shared a large distinct subset of genes, nonetheless the number of unique and accessory genes is quite large and defines the pan-genome as open. Enzymatic screens indicate that a vast array of enzyme activities is expressed by the isolates, including β-galactosidase, β-glucosidase, and protease activities. A β-glucosidase gene from one of the Pseudoalteromonas isolates, strain EB27 was heterologously expressed in Escherichia coli and, following biochemical characterization, the recombinant enzyme was found to be cold-adapted, thermolabile, halotolerant, and alkaline active. PMID:28629190

  15. Antarctic Fishes.

    ERIC Educational Resources Information Center

    Eastman, Joseph T.; DeVries, Arthur L.

    1986-01-01

    Explains the adaptations to Antarctic waters that Notothenioidei, a group of advanced bony fishes, have exhibited. Discusses the fishes' mechanisms of production of antifreeze properties and their capacities for neutral buoyancy in water. (ML)

  16. Antarctic Entomology.

    PubMed

    Chown, Steven L; Convey, Peter

    2016-01-01

    The Antarctic region comprises the continent, the Maritime Antarctic, the sub-Antarctic islands, and the southern cold temperate islands. Continental Antarctica is devoid of insects, but elsewhere diversity varies from 2 to more than 200 species, of which flies and beetles constitute the majority. Much is known about the drivers of this diversity at local and regional scales; current climate and glacial history play important roles. Investigations of responses to low temperatures, dry conditions, and varying salinity have spanned the ecological to the genomic, revealing new insights into how insects respond to stressful conditions. Biological invasions are common across much of the region and are expected to increase as climates become warmer. The drivers of invasion are reasonably well understood, although less is known about the impacts of invasion. Antarctic entomology has advanced considerably over the past 50 years, but key areas, such as interspecific interactions, remain underexplored.

  17. Antarctic Fishes.

    ERIC Educational Resources Information Center

    Eastman, Joseph T.; DeVries, Arthur L.

    1986-01-01

    Explains the adaptations to Antarctic waters that Notothenioidei, a group of advanced bony fishes, have exhibited. Discusses the fishes' mechanisms of production of antifreeze properties and their capacities for neutral buoyancy in water. (ML)

  18. Lipid A structure of Pseudoalteromonas haloplanktis TAC 125: use of electrospray ionization tandem mass spectrometry for the determination of fatty acid distribution.

    PubMed

    Corsaro, Maria Michela; Piaz, Fabrizio Dal; Lanzetta, Rosa; Parrilli, Michelangelo

    2002-05-01

    The use of electrospray Ionization (ESI) tandem mass spectrometry (MS/MS) for the structural determination of the lipid A components of the psychrophilic bacterium Pseudoalteromonas haloplanktis TAC 125 is reported. The lipid A contains the classical bisphosphorylated beta-(1' --> 6)-linked D-glucosamine disaccharide with 3-hydroxydodecanoyl residues (12 : 0 (3-OH)) linked both as esters and amides to 2', 3' (distal glucosamine) and 2, 3 positions (proximal glucosamine) of the sugar backbone. The hydroxyl of 12 : 0 (3-OH) fatty acid linked at the 3' position is esterified by a dodecanoyl residue (12 : 0). In addition to the pentaacyl component, a minor tetraacyl lipid A, lacking the acyl residue at position 3, was also found in the lipid A fraction. The advantage of this MS technique for the investigation of the intra-ring fragmentation, which is useful for the determination of fatty acyl residue distribution on each glucosamine unit, is emphasized.

  19. Antarctic meteorites

    NASA Astrophysics Data System (ADS)

    Cassidy, W. A.; Rancitelli, L. A.

    1982-04-01

    An abundance of meteorites has been discovered on two sites in the Antarctic which may assist in the study of the origins of meteorites and the history of the solar system. Characteristics particular to those meteorites discovered in this region are explained. These specimens, being well preserved due to the climate, have implications in the study of the cosmic ray flux through time, the meteoroid complex in space, and cosmic ray exposure ages. Implications for the study of the Antarctic, particularly the ice flow, are also discussed. Further discoveries of meteorites in this region are anticipated.

  20. Effects of Pseudoalteromonas sp. BC228 on digestive enzyme activity and immune response of juvenile sea cucumber ( Apostichopus japonicus)

    NASA Astrophysics Data System (ADS)

    Ma, Yuexin; Sun, Feixue; Zhang, Congyao; Bao, Pengyun; Cao, Shuqing; Zhang, Meiyan

    2014-12-01

    A marine bacterium, Pseudoalteromonas sp. BC228 was supplemented to feed in a feeding experiment aiming to determine its ability of enhancing the digestive enzyme activity and immune response of juvenile Apostichopus japonicus. Sea cucumber individuals were fed with the diets containing 0 (control), 105, 107 and 109 CFU g-1 diet of BC228 for 45 days. Results showed that intestinal trypsin and lipase activities were significantly enhanced by 107 and 109 CFU g-1 diet of BC228 in comparison with control ( P < 0.01). The phagocytic activity in the coelomocytes of sea cucumber fed the diet supplemented with 107 CFU g-1 diet of BC228 was significantly higher than that of those fed control diet ( P < 0.05). In addition, 105 and 107 CFU g-1 diet of BC228 significantly enhanced lysozyme and phenoloxidase activities in the coelomic fluid of sea cucumber, respectively, in comparison with other diets ( P < 0.01). Sea cucumbers, 10 each diet, were challenged with Vibrio splendidus NB13 after 45 days of feeding. It was found that the cumulative incidence and mortality of sea cucumber fed with BC228 containing diets were lower than those of animals fed control diet. Our findings evidenced that BC228 supplemented in diets improved the digestive enzyme activity of juvenile sea cucumber, stimulated its immune response and enhanced its resistance to the infection of V. splendidus.

  1. The peculiar heme pocket of the 2/2 hemoglobin of cold-adapted Pseudoalteromonas haloplanktis TAC125.

    PubMed

    Howes, Barry D; Giordano, Daniela; Boechi, Leonardo; Russo, Roberta; Mucciacciaro, Simona; Ciaccio, Chiara; Sinibaldi, Federica; Fittipaldi, Maria; Martí, Marcelo A; Estrin, Darío A; di Prisco, Guido; Coletta, Massimo; Verde, Cinzia; Smulevich, Giulietta

    2011-02-01

    The genome of the cold-adapted bacterium Pseudoalteromonas haloplanktis TAC125 contains multiple genes encoding three distinct monomeric hemoglobins exhibiting a 2/2 α-helical fold. In the present work, one of these hemoglobins is studied by resonance Raman, electronic absorption and electronic paramagnetic resonance spectroscopies, kinetic measurements, and different bioinformatic approaches. It is the first cold-adapted bacterial hemoglobin to be characterized. The results indicate that this protein belongs to the 2/2 hemoglobin family, Group II, characterized by the presence of a tryptophanyl residue on the bottom of the heme distal pocket in position G8 and two tyrosyl residues (TyrCD1 and TyrB10). However, unlike other bacterial hemoglobins, the ferric state, in addition to the aquo hexacoordinated high-spin form, shows multiple hexacoordinated low-spin forms, where either TyrCD1 or TyrB10 can likely coordinate the iron. This is the first example in which both TyrCD1 and TyrB10 are proposed to be the residues that are alternatively involved in heme hexacoordination by endogenous ligands.

  2. Draft Genome Sequence of Pseudoalteromonas sp. Strain ECSMB14103, Isolated from the East China Sea.

    PubMed

    Guo, Xing-Pan; Ding, De-Wen; Bao, Wei-Yang; Yang, Jin-Long

    2015-04-23

    Pseudoalteromonas sp. strain ECSMB14103 was isolated from marine biofilms formed on the East China Sea. The draft genome sequence comprises 4.11 Mp with a G+C content of 39.7%. The information from the draft genome will contribute to an understanding of bacteria-animal interaction. Copyright © 2015 Guo et al.

  3. Six Pseudoalteromonas Strains Isolated from Surface Waters of Kabeltonne, Offshore Helgoland, North Sea

    PubMed Central

    Wichels, Antje; Sullivan, Matthew B.

    2016-01-01

    Draft genomes are presented for 6 Pseudoalteromonas sp. strains isolated from surface waters at Kabeltonne, Helgoland, a long-term ecological research station in the North Sea. These strains contribute knowledge of the genomic underpinnings of a developing model system to study phage-host dynamics of a particle-associated ocean copiotroph. PMID:26868390

  4. Draft Genome Sequence of Marine Sponge Symbiont Pseudoalteromonas luteoviolacea IPB1, Isolated from Hilo, Hawaii.

    PubMed

    Sakai-Kawada, Francis E; Yakym, Christopher J; Helmkampf, Martin; Hagiwara, Kehau; Ip, Courtney G; Antonio, Brandi J; Armstrong, Ellie; Ulloa, Wesley J; Awaya, Jonathan D

    2016-09-22

    We report here the 6.0-Mb draft genome assembly of Pseudoalteromonas luteoviolacea strain IPB1 that was isolated from the Hawaiian marine sponge Iotrochota protea Genome mining complemented with bioassay studies will elucidate secondary metabolite biosynthetic pathways and will help explain the ecological interaction between host sponge and microorganism.

  5. MALDI-TOF Mass Spectrometry Discriminates Known Species and Marine Environmental Isolates of Pseudoalteromonas.

    PubMed

    Emami, Kaveh; Nelson, Andrew; Hack, Ethan; Zhang, Jinwei; Green, David H; Caldwell, Gary S; Mesbahi, Ehsan

    2016-01-01

    The genus Pseudoalteromonas constitutes an ecologically significant group of marine Gammaproteobacteria with potential biotechnological value as producers of bioactive compounds and of enzymes. Understanding their roles in the environment and bioprospecting for novel products depend on efficient ways of identifying environmental isolates. Matrix Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) biotyping has promise as a rapid and reliable method of identifying and distinguishing between different types of bacteria, but has had relatively limited application to marine bacteria and has not been applied systematically to Pseudoalteromonas. Therefore, we constructed a MALDI-TOF MS database of 31 known Pseudoalteromonas species, to which new isolates can be compared by MALDI-TOF biotyping. The ability of MALDI-TOF MS to distinguish between species was scrutinized by comparison with 16S rRNA gene sequencing. The patterns of similarity given by the two approaches were broadly but not completely consistent. In general, the resolution of MALDI-TOF MS was greater than that of 16S rRNA gene sequencing. The database was tested with 13 environmental Pseudoalteromonas isolates from UK waters. All of the test strains could be identified to genus level by MALDI-TOF MS biotyping, but most could not be definitely identified to species level. We conclude that several of these isolates, and possibly most, represent new species. Thus, further taxonomic investigation of Pseudoalteromonas is needed before MALDI-TOF MS biotyping can be used reliably for species identification. It is, however, a powerful tool for characterizing and distinguishing among environmental isolates and can make an important contribution to taxonomic studies.

  6. Improving Production of Protease from Pseudoalteromonas sp. CSN423 by Random Mutagenesis.

    PubMed

    Wu, Cuiling; Liu, Dan; Yang, Xinghao; Wu, Ribang; Zhang, Jiang; Huang, Jiafeng; He, Hailun

    2016-10-01

    Pseudoalteromonas sp. CSN423, a marine strain, can express a major protease designated as E423 and it was secreted into the supernatant. To improve the protease E423 yield, Pseudoalteromonas sp. CSN423 was subjected to mutagenesis using UV irradiation. Mutant strain with 5.1-fold higher protease yield was isolated and named as Pseudoalteromonas sp. CSN423-M. Three protease bands were detected by zymography with casein as substrate, and results of mass spectrometry (MS) showed that two lower molecular weight protein bands were the same protease but with different mature forms. The entire protease operon was sequenced and no mutation was found. Mutant strain-associated changes of expression levels of protease synthesis and secretion-related genes were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Mutant strain had higher expression of e423 than wild-type strain. Such result was consistent with protease activity profiles. Moreover, the mutant strain had higher transcriptional levels of citrate synthase (cs), α-ketoglutarate decarboxylase (kgd), cytochrome c oxidase subunit I (coxI), tolC, hlyD (membrane protein), luxR3, luxO, and luxT (transcriptional regulator). However, hexokinase (hk), pyruvate dehydrogenase E1 (pd-e1), epsD (membrane protein), and luxR1 remained unchanged, and luxR2 decreased sharply in the mutant. These results suggested that the redox pathway was promoted in the mutant strain, and LuxR family transcriptional regulators in Pseudoalteromonas spp. may play some role in regulating protease expression. Meanwhile, the secretion of extracellular protease was closely related to ABC transport system. These results may shed some light on the molecular mechanism underlying higher yield of protease E423 from Pseudoalteromonas sp. CSN423-M.

  7. Antarctic Genomics

    PubMed Central

    Clarke, Andrew; Cockell, Charles S.; Convey, Peter; Detrich III, H. William; Fraser, Keiron P. P.; Johnston, Ian A.; Methe, Barbara A.; Murray, Alison E.; Peck, Lloyd S.; Römisch, Karin; Rogers, Alex D.

    2004-01-01

    With the development of genomic science and its battery of technologies, polar biology stands on the threshold of a revolution, one that will enable the investigation of important questions of unprecedented scope and with extraordinary depth and precision. The exotic organisms of polar ecosystems are ideal candidates for genomic analysis. Through such analyses, it will be possible to learn not only the novel features that enable polar organisms to survive, and indeed thrive, in their extreme environments, but also fundamental biological principles that are common to most, if not all, organisms. This article aims to review recent developments in Antarctic genomics and to demonstrate the global context of such studies. PMID:18629155

  8. Antarctic science

    NASA Astrophysics Data System (ADS)

    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.

  9. Antarctic micrometeorites

    NASA Technical Reports Server (NTRS)

    Kurat, G.; Koeberl, C.; Presper, T.; Brandstaetter, F.; Maurette, Michel

    1994-01-01

    Micrometeoroids in the size range 50-500 micron dominate the flux onto the Earth. Contrary to theoretical predictions, many of them survive atmospheric entry almost unchanged. Such micrometeorites can be collected from the Antarctic ice sheet where they account for a surprisingly large proportion of the total dust content of the ice. Early studies of this important class of extraterrestrial material have revealed that some Antarctic micrometeorites are similar to CM chondrites in chemical bulk composition and mineral composition, and a few seem to resemble CI chondrites. However, none of the micrometeorites investigated so far match CM or CI chondrites exactly, nor is there a match between average bulk micrometeorite composition and that of any other chondrite class. Also, the micrometeorite mineral chemistry is different from that of carbonaceous chondrites. Several elements are depleted in micrometeorites as compared to carbonaceous chondrites and some are enriched. The question arises whether these differences are pristine or if some of them are of secondary origin. On the basis of our data we will attempt to answer these questions, some of which have been addressed by us before.

  10. A cold-adapted esterase of a novel marine isolate, Pseudoalteromonas arctica: gene cloning, enzyme purification and characterization.

    PubMed

    Al Khudary, Rami; Venkatachalam, Ramprasath; Katzer, Moritz; Elleuche, Skander; Antranikian, Garabed

    2010-05-01

    A gene encoding an esterase (estO) was identified and sequenced from a gene library screen of the psychrotolerant bacterium Pseudoalteromonas arctica. Analysis of the 1,203 bp coding region revealed that the deduced peptide sequence is composed of 400 amino acids with a predicted molecular mass of 44.1 kDa. EstO contains a N-terminal esterase domain and an additional OsmC domain at the C-terminus (osmotically induced family of proteins). The highly conserved five-residue motif typical for all alpha/beta hydrolases (G x S x G) was detected from position 104 to 108 together with a putative catalytic triad consisting of Ser(106), Asp(196), and His(225). Sequence comparison showed that EstO exhibits 90% amino acid identity with hypothetical proteins containing similar esterase and OsmC domains but only around 10% identity to the amino acid sequences of known esterases. EstO variants with and without the OsmC domain were produced and purified as His-tag fusion proteins in E. coli. EstO displayed an optimum pH of 7.5 and optimum temperature of 25 degrees C with more than 50% retained activity at the freezing point of water. The thermostability of EstO (50% activity after 5 h at 40 degrees C) dramatically increased in the truncated variant (50% activity after 2.5 h at 90 degrees C). Furthermore, the esterase displays broad substrate specificity for esters of short-chain fatty acids (C(2)-C(8)).

  11. [Antibiotic properties of the Pseudoalteromonas genus bacteria isolated from the Black Sea water and molluscs].

    PubMed

    Onyshchenko, O M; Kiprianova, O A; Lysenko, T H; Smirnov, V V

    2002-01-01

    Antagonistic properties of 41 strains of Alteromonas-like bacteria isolated from the Black Sea water and molluscs have been studied. Being grown on the rich medium "B" for marine bacteria, 21% of strains have shown high antagonistic activity against phytopathogenic fungi; 6% of strains inhibited the growth of Bacillus subtilis, Proteus vulgaris and Candida albicans. Spectrum of antagonistic activity was essentially changed on synthetic "BM" medium with acetate, glutamate, alpha-alanine as a single source of carbon and was directed against Pseudomonas aeruginosa. Culture liquids and acetone extracts of microbial biomass of 34% of the studied strains have shown activity against bacteria, fungi and cyanobacteria. Strains producing the wide spectrum of antimicrobial substances (Alteromonas macleodii, Pseudoalteromonas citrea, P. haloplanktis, P. aurantia, Pseudoalteromonas sp.), fungicidal and algocidal substances have been found. Both extra- and intracellular metabolities of marine bacteria (including the pigments) were active.

  12. Draft Genome Sequence of Pseudoalteromonas sp. Strain PAB 2.2 Isolated from Abrolhos Bank (Brazil).

    PubMed

    Silva, Bruno S O; Nobrega, Maria S; Leomil, Luciana; Tschoeke, Diogo A; Garcia, Gizele D; Dias, Graciela; Thompson, Cristiane C; Thompson, Fabiano L

    2017-03-09

    We present here the draft genome sequence of Pseudoalteromonas sp. strain PAB 2.2, isolated from water of Parcel de Abrolhos coral reef (17°57'32.7″; 38°30'20.3″), on Abrolhos Bank, at a depth of 12 m. The assembly consists of 4,434,635 bp and contains 40 contigs, with a G+C content of 41.60%.

  13. Draft Genome Sequence of Pseudoalteromonas sp. Strain PAB 2.2 Isolated from Abrolhos Bank (Brazil)

    PubMed Central

    Silva, Bruno S. O.; Nobrega, Maria S.; Leomil, Luciana; Tschoeke, Diogo A.; Garcia, Gizele D.; Dias, Graciela; Thompson, Cristiane C.

    2017-01-01

    ABSTRACT We present here the draft genome sequence of Pseudoalteromonas sp. strain PAB 2.2, isolated from water of Parcel de Abrolhos coral reef (17°57′32.7″; 38°30′20.3″), on Abrolhos Bank, at a depth of 12 m. The assembly consists of 4,434,635 bp and contains 40 contigs, with a G+C content of 41.60%. PMID:28280012

  14. Biofilm formation and proteolytic activities of Pseudoalteromonas bacteria that were isolated from fish farm sediments

    PubMed Central

    Iijima, Saori; Washio, Kenji; Okahara, Ryota; Morikawa, Masaaki

    2009-01-01

    Summary In order to save natural resources and supply good fishes, it is important to improve fish‐farming techniques. The survival rate of fish fry appears to become higher when powders of foraminifer limestone are submerged at the bottom of fish‐farming fields, where bacterial biofilms often grow. The observations suggest that forming biofilms can benefit to keep health status of breeding fishes. We employed culture‐based methods for the identification and characterization of biofilm‐forming bacteria and assessed the application of their properties for fish farming. Fifteen bacterial strains were isolated from the biofilm samples collected from fish farm sediments. The 16S rRNA gene sequences indicated that these bacteria belonged to the genera, Pseudoalteromonas (seven strains), Vibrio (seven strains) and Halomonas (one strain). It was found that Pseudoalteromonas strains generally formed robust biofilms in a laboratory condition and produced extracellular proteases in a biofilm‐dependent manner. The results suggest that Pseudoalteromonas bacteria, living in the biofilm community, contribute in part to remove excess proteineous matters from the sediment sludge of fish farms. PMID:21261930

  15. Ecogenomics and genome landscapes of marine Pseudoalteromonas phage H105/1

    PubMed Central

    Duhaime, Melissa Beth; Wichels, Antje; Waldmann, Jost; Teeling, Hanno; Glöckner, Frank Oliver

    2011-01-01

    Marine phages have an astounding global abundance and ecological impact. However, little knowledge is derived from phage genomes, as most of the open reading frames in their small genomes are unknown, novel proteins. To infer potential functional and ecological relevance of sequenced marine Pseudoalteromonas phage H105/1, two strategies were used. First, similarity searches were extended to include six viral and bacterial metagenomes paired with their respective environmental contextual data. This approach revealed ‘ecogenomic' patterns of Pseudoalteromonas phage H105/1, such as its estuarine origin. Second, intrinsic genome signatures (phylogenetic, codon adaptation and tetranucleotide (tetra) frequencies) were evaluated on a resolved intra-genomic level to shed light on the evolution of phage functional modules. On the basis of differential codon adaptation of Phage H105/1 proteins to the sequenced Pseudoalteromonas spp., regions of the phage genome with the most ‘host'-adapted proteins also have the strongest bacterial tetra signature, whereas the least ‘host'-adapted proteins have the strongest phage tetra signature. Such a pattern may reflect the evolutionary history of the respective phage proteins and functional modules. Finally, analysis of the structural proteome identified seven proteins that make up the mature virion, four of which were previously unknown. This integrated approach combines both novel and classical strategies and serves as a model to elucidate ecological inferences and evolutionary relationships from phage genomes that typically abound with unknown gene content. PMID:20613791

  16. Biofilm formation and proteolytic activities of Pseudoalteromonas bacteria that were isolated from fish farm sediments.

    PubMed

    Iijima, Saori; Washio, Kenji; Okahara, Ryota; Morikawa, Masaaki

    2009-05-01

    In order to save natural resources and supply good fishes, it is important to improve fish-farming techniques. The survival rate of fish fry appears to become higher when powders of foraminifer limestone are submerged at the bottom of fish-farming fields, where bacterial biofilms often grow. The observations suggest that forming biofilms can benefit to keep health status of breeding fishes. We employed culture-based methods for the identification and characterization of biofilm-forming bacteria and assessed the application of their properties for fish farming. Fifteen bacterial strains were isolated from the biofilm samples collected from fish farm sediments. The 16S rRNA gene sequences indicated that these bacteria belonged to the genera, Pseudoalteromonas (seven strains), Vibrio (seven strains) and Halomonas (one strain). It was found that Pseudoalteromonas strains generally formed robust biofilms in a laboratory condition and produced extracellular proteases in a biofilm-dependent manner. The results suggest that Pseudoalteromonas bacteria, living in the biofilm community, contribute in part to remove excess proteineous matters from the sediment sludge of fish farms. © 2009 The Authors. Journal compilation © 2009 Society for Applied Microbiology and Blackwell Publishing Ltd.

  17. Comparative Omics and Trait Analyses of Marine Pseudoalteromonas Phages Advance the Phage OTU Concept

    PubMed Central

    Duhaime, Melissa B.; Solonenko, Natalie; Roux, Simon; Verberkmoes, Nathan C.; Wichels, Antje; Sullivan, Matthew B.

    2017-01-01

    Viruses influence the ecology and evolutionary trajectory of microbial communities. Yet our understanding of their roles in ecosystems is limited by the paucity of model systems available for hypothesis generation and testing. Further, virology is limited by the lack of a broadly accepted conceptual framework to classify viral diversity into evolutionary and ecologically cohesive units. Here, we introduce genomes, structural proteomes, and quantitative host range data for eight Pseudoalteromonas phages isolated from Helgoland (North Sea, Germany) and use these data to advance a genome-based viral operational taxonomic unit (OTU) definition. These viruses represent five new genera and inform 498 unaffiliated or unannotated protein clusters (PCs) from global virus metagenomes. In a comparison of previously sequenced Pseudoalteromonas phage isolates (n = 7) and predicted prophages (n = 31), the eight phages are unique. They share a genus with only one other isolate, Pseudoalteromonas podophage RIO-1 (East Sea, South Korea) and two Pseudoalteromonas prophages. Mass-spectrometry of purified viral particles identified 12–20 structural proteins per phage. When combined with 3-D structural predictions, these data led to the functional characterization of five previously unidentified major capsid proteins. Protein functional predictions revealed mechanisms for hijacking host metabolism and resources. Further, they uncovered a hybrid sipho-myovirus that encodes genes for Mu-like infection rarely described in ocean systems. Finally, we used these data to evaluate a recently introduced definition for virus populations that requires members of the same population to have >95% average nucleotide identity across at least 80% of their genes. Using physiological traits and genomics, we proposed a conceptual model for a viral OTU definition that captures evolutionarily cohesive and ecologically distinct units. In this trait-based framework, sensitive hosts are considered viral

  18. Physiological and genetic analyses reveal a mechanistic insight into the multifaceted lifestyles of Pseudoalteromonas sp. SM9913 adapted to the deep-sea sediment.

    PubMed

    Mi, Zi-Hao; Yu, Zi-Chao; Su, Hai-Nan; Wang, Lei; Chen, Xiu-Lan; Pang, Xiuhua; Qin, Qi-Long; Xie, Bin-Bin; Zhang, Xi-Ying; Zhou, Bai-Cheng; Zhang, Yu-Zhong

    2015-10-01

    Although bacteriobenthos play a major role in the degradation of particulate organic matter in marine sediment, knowledge of the sediment-adapted lifestyles of bacteriobenthos is still scarce. Here, the particle-associated, swimming and swarming lifestyles of the benthonic bacterium Pseudoalteromonas sp. SM9913 (SM9913) were illustrated. SM9913 had a clay particle-associated lifestyle, and its exopolysaccharide played an important role in this lifestyle. SM9913 also had swimming and swarming motilities, indicating that it may have swimming and swarming lifestyles in the sediment. The lateral flagella were responsible for the swarming motility, and the polar flagella were responsible for the swimming motility. Iron limitation was an indispensable inductive signal of the swarming motility. An analysis of the motilities of SM9913 and its mutants in clay demonstrated that SM9913 moved in clay by both swimming and swarming motilities. Genomic analysis suggests that having two flagella systems is most likely a common adaptation of some bacteriobenthos to the sediment environment. Our results reveal the lifestyles of benthonic SM9913, providing a better understanding of the environmental adaptation of benthonic bacteria.

  19. Fusion of the OsmC domain from esterase EstO confers thermolability to the cold-active xylanase Xyn8 from Pseudoalteromonas arctica.

    PubMed

    Elleuche, Skander; Piascheck, Henning; Antranikian, Garabed

    2011-03-01

    The OsmC-region (osmotically induced protein family) of the two-domain esterase EstO from the psychrotolerant bacterium Pseudoalteromonas arctica has been shown to increase thermolability. In an attempt to test if these properties can be conferred to another enzyme, we genetically fused osmC to the 3'-region of the family 8 xylanase encoding gene xyn8 from P. arctica. The chimeric open reading frame xyn8-OsmC was cloned and the chimeric protein was purified after heterologous expression in Escherichia coli. Xyn8 and Xyn8-OsmC showed cold-adapted properties (more than 60% activity at 0°C) using birchwood xylan as the preferred substrate. Maximal catalytic activity is slightly shifted from 15°C (Xyn8) to 20°C for Xyn8-OsmC. Thermostability of Xyn8-OsmC is significantly changed in comparison to wild-type Xyn8. The OsmC-fusion variant showed an apparent decrease in thermostability between 40 and 45°C, while both proteins are highly instable at 50°C.

  20. Histopathology of Antarctic krill, Euphausia superba, bearing black spots.

    PubMed

    Miwa, S; Kamaishi, T; Matsuyama, T; Hayashi, T; Naganobu, M

    2008-07-01

    Small black spots have been noticed on the cephalothorax of Antarctic krill, Euphausia superba, since January, 2001. To study the nature of the black spots, the krill were sampled in the winter of 2003, 2006, and 2007 in the South Georgia region, the Antarctic Ocean. Histological observations revealed that the black spots were melanized nodules that were composed of hemocytes surrounding either bacteria or amorphous material. In the 2007 samples, 42% of the krill had melanized nodules. Most of the nodules had an opening on the body surface of the krill. A single melanized nodule often contained more than one type of morphologically distinct bacterial cell. Three bacteria were isolated from these black spots, and classified into either Psychrobacter or Pseudoalteromonas based on the sequences of 16S rRNA genes. More than three bacterial species or strains were also confirmed by in situ hybridization for 16S rRNA. The melanized nodules were almost always accompanied by a mass of atypical, large heteromorphic cells, which were not observed in apparently healthy krill. Unidentified parasites were observed in some of the krill that had melanized nodules. These parasites were directly surrounded by the large heteromorphic cells. Histological observations suggested that these heteromorphic cells were attacking the parasites. These results suggest the possibility that the krill had been initially affected by parasite infections, and the parasitized spots were secondary infected by environmental bacteria after the parasites had escaped from the host body.

  1. Microbial mercury methylation in Antarctic sea ice.

    PubMed

    Gionfriddo, Caitlin M; Tate, Michael T; Wick, Ryan R; Schultz, Mark B; Zemla, Adam; Thelen, Michael P; Schofield, Robyn; Krabbenhoft, David P; Holt, Kathryn E; Moreau, John W

    2016-08-01

    Atmospheric deposition of mercury onto sea ice and circumpolar sea water provides mercury for microbial methylation, and contributes to the bioaccumulation of the potent neurotoxin methylmercury in the marine food web. Little is known about the abiotic and biotic controls on microbial mercury methylation in polar marine systems. However, mercury methylation is known to occur alongside photochemical and microbial mercury reduction and subsequent volatilization. Here, we combine mercury speciation measurements of total and methylated mercury with metagenomic analysis of whole-community microbial DNA from Antarctic snow, brine, sea ice and sea water to elucidate potential microbially mediated mercury methylation and volatilization pathways in polar marine environments. Our results identify the marine microaerophilic bacterium Nitrospina as a potential mercury methylator within sea ice. Anaerobic bacteria known to methylate mercury were notably absent from sea-ice metagenomes. We propose that Antarctic sea ice can harbour a microbial source of methylmercury in the Southern Ocean.

  2. Analysis of the Pseudoalteromonas tunicata Genome Reveals Properties of a Surface-Associated Life Style in the Marine Environment

    PubMed Central

    Thomas, Torsten; Evans, Flavia F.; Schleheck, David; Mai-Prochnow, Anne; Burke, Catherine; Penesyan, Anahit; Dalisay, Doralyn S.; Stelzer-Braid, Sacha; Saunders, Neil; Johnson, Justin; Ferriera, Steve; Kjelleberg, Staffan; Egan, Suhelen

    2008-01-01

    Background Colonisation of sessile eukaryotic host surfaces (e.g. invertebrates and seaweeds) by bacteria is common in the marine environment and is expected to create significant inter-species competition and other interactions. The bacterium Pseudoalteromonas tunicata is a successful competitor on marine surfaces owing primarily to its ability to produce a number of inhibitory molecules. As such P. tunicata has become a model organism for the studies into processes of surface colonisation and eukaryotic host-bacteria interactions. Methodology/Principal Findings To gain a broader understanding into the adaptation to a surface-associated life-style, we have sequenced and analysed the genome of P. tunicata and compared it to the genomes of closely related strains. We found that the P. tunicata genome contains several genes and gene clusters that are involved in the production of inhibitory compounds against surface competitors and secondary colonisers. Features of P. tunicata's oxidative stress response, iron scavenging and nutrient acquisition show that the organism is well adapted to high-density communities on surfaces. Variation of the P. tunicata genome is suggested by several landmarks of genetic rearrangements and mobile genetic elements (e.g. transposons, CRISPRs, phage). Surface attachment is likely to be mediated by curli, novel pili, a number of extracellular polymers and potentially other unexpected cell surface proteins. The P. tunicata genome also shows a utilisation pattern of extracellular polymers that would avoid a degradation of its recognised hosts, while potentially causing detrimental effects on other host types. In addition, the prevalence of recognised virulence genes suggests that P. tunicata has the potential for pathogenic interactions. Conclusions/Significance The genome analysis has revealed several physiological features that would provide P. tunciata with competitive advantage against other members of the surface-associated community

  3. Antarctic culture: 50 years of Antarctic expeditions.

    PubMed

    Sarris, Aspa

    2007-09-01

    Analyses of data collected on returned Australian Antarctic personnel were conducted to examine links between personality traits, perceptions of Antarctic station culture, and perceptions of subjective fit with Antarctic station life and culture. Participants were 103 men who participated in Australian National Antarctic Research Expeditions (ANARE) over a 50-yr period from 1950 to 2000 representing the first 50 yr of ANARE and all positions and occupations included in Australian Antarctic expeditions. Participants completed self-report measures of personality, organizational culture, and subjective fit. Results showed that those who described the culture as satisfaction-oriented (more friendly and participatory) reported better fit, increased satisfaction with their group membership, and less role conflict in terms of their work role. Results also showed a relationship between personality, perceptions of behavioral norms and expectations, and perceived fit. Specifically, openness and perceptions of station culture as satisfaction-oriented were identified as predictors of good fit with station life and culture. The implications of the results for Antarctic personnel selection and recruitment are discussed and the importance of further research in other analogous isolated, confined, and extreme settings is highlighted.

  4. The Antarctic ozone hole

    NASA Astrophysics Data System (ADS)

    Molina, Mario J.

    Observations of Antarctic ozone levels and the discovery of a hole in the Antarctic region are examined. The effects of chlorofluorocarbons (CFCs) on the level of stratospheric ozone are analyzed. Three cycles explaining the cause of ozone depletion in the poles are proposed. A comparison of field data and proposed depletion cycles reveals that the chemical origin of the ozone hole is due to CFCs. The potential global effects of the Antarctic ozone hole are discussed.

  5. Exopolysaccharide production by a marine Pseudoalteromonas sp. strain isolated from Madeira Archipelago ocean sediments.

    PubMed

    Roca, Christophe; Lehmann, Mareen; Torres, Cristiana A V; Baptista, Sílvia; Gaudêncio, Susana P; Freitas, Filomena; Reis, Maria A M

    2016-06-25

    Exopolysaccharides (EPS) are polymers excreted by some microorganisms with interesting properties and used in many industrial applications. A new Pseudoalteromonas sp. strain, MD12-642, was isolated from marine sediments and cultivated in bioreactor in saline culture medium containing glucose as carbon source. Its ability to produce EPS under saline conditions was demonstrated reaching an EPS production of 4.4g/L within 17hours of cultivation, corresponding to a volumetric productivity of 0.25g/Lh, the highest value so far obtained for Pseudoalteromonas sp. strains. The compositional analysis of the EPS revealed the presence of galacturonic acid (41-42mol%), glucuronic acid (25-26mol%), rhamnose (16-22mol%) and glucosamine (12-16mol%) sugar residues. The polymer presents a high molecular weight (above 1000kDa). These results encourage the biotechnological exploitation of strain MD12-642 for the production of valuable EPS with unique composition, using saline by-products/wastes as feedstocks. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Purification and characterization of antibacterial compounds of Pseudoalteromonas flavipulchra JG1.

    PubMed

    Yu, Min; Wang, Junfeng; Tang, Kaihao; Shi, Xiaochong; Wang, Shushan; Zhu, Wei-Ming; Zhang, Xiao-Hua

    2012-03-01

    Pseudoalteromonas flavipulchra JG1 produces a protein PfaP and a range of small-molecule compounds with inhibitory activities against Vibrio anguillarum. The PfaP protein was purified from the extracellular products of JG1 by electroelution, and antibacterial activity was observed by an in-gel antibacterial assay. The complete amino acid sequence (694 aa) of PfaP was determined by de novo peptide sequencing and subsequent alignment with the proteome sequence of strain JG1. The calculated molecular mass of PfaP was 77.0 kDa. PfaP was 58 % identical to l-lysine oxidase AlpP of Pseudoalteromonas tunicata D2, and 54 % identical to the marinocine antimicrobial protein of Marinomonas mediterranea MMB-1. Five small molecules (compounds 1-5) with antibacterial activity, which were identified as p-hydroxybenzoic acid (1), trans-cinnamic acid (2), 6-bromoindolyl-3-acetic acid (3), N-hydroxybenzoisoxazolone (4) and 2'-deoxyadenosine (5), were purified by sequential column chromatography over silica gel, Sephadex LH-20 and RP-18 from ethyl acetate extract of strain JG1, and their structures were determined by NMR and MS. Brown compound 3, the only brominated compound, showed antibacterial activity against both Gram-positive and Gram-negative bacteria.

  7. Identification, cloning, and expression of L-amino acid oxidase from marine Pseudoalteromonas sp. B3.

    PubMed

    Yu, Zhiliang; Zhou, Ning; Qiao, Hua; Qiu, Juanping

    2014-01-01

    L-amino acid oxidase (LAAO) is attracting more attentions due to its broad and important biological functions. Recently, an LAAO-producing marine microorganism (strain B3) was isolated from the intertidal zone of Dinghai sea area, China. Physiological, biochemical, and molecular identifications together with phylogenetic analysis congruously suggested that it belonged to the genus Pseudoalteromonas. Therefore, it was designated as Pseudoalteromonas sp. B3. Its capability of LAAO production was crossly confirmed by measuring the products of H2O2, a-keto acids, and NH4+ in oxidization reaction. Two rounds of PCR were performed to gain the entire B3-LAAO gene sequence of 1608 bps in length encoding for 535 amino acid residues. This deduced amino acid sequence showed 60 kDa of the calculated molecular mass, supporting the SDS-PAGE result. Like most of flavoproteins, B3-LAAO also contained two conserved typical motifs, GG-motif and βαβ-dinucleotide-binding domain motif. On the other hand, its unique substrate spectra and sequence information suggested that B3-LAAO was a novel LAAO. Our results revealed that it could be functionally expressed in E. coli BL21(DE3) using vectors, pET28b(+) and pET20b(+). However, compared with the native LAAO, the expression level of the recombinant one was relatively low, most probably due to the formation of inclusion bodies. Several solutions are currently being conducted in our lab to increase its expression level.

  8. Bioactive compound synthetic capacity and ecological significance of marine bacterial genus pseudoalteromonas.

    PubMed

    Bowman, John P

    2007-12-18

    The genus Pseudoalteromonas is a marine group of bacteria belonging to the class Gammaproteobacteria that has come to attention in the natural product and microbial ecology science fields in the last decade. Pigmented species of the genus have been shown to produce an array of low and high molecular weight compounds with antimicrobial, anti-fouling, algicidal and various pharmaceutically-relevant activities. Compounds formed include toxic proteins, polyanionic exopolymers, substituted phenolic and pyrolle-containing alkaloids, cyclic peptides and a range of bromine-substituted compounds. Ecologically, Pseudoalteromonas appears significant and to date has been shown to influence biofilm formation in various marine econiches; involved in predator-like interactions within the microbial loop; influence settlement, germination and metamorphosis of various invertebrate and algal species; and may also be adopted by marine flora and fauna as defensive agents. Studies have been so far limited to a relatively small subset of strains compared to the known diversity of the genus suggesting that many more discoveries of novel natural products as well as ecological connections these may have in the marine ecosystem remain to be made.

  9. The Antarctic Ozone Hole.

    ERIC Educational Resources Information Center

    Stolarski, Richard S.

    1988-01-01

    Discusses the Airborne Antarctic Ozone Experiment (1987) and the findings of the British Antarctic Survey (1985). Proposes two theories for the appearance of the hole in the ozone layer over Antarctica which appears each spring; air pollution and natural atmospheric shifts. Illustrates the mechanics of both. Supports worldwide chlorofluorocarbon…

  10. The Antarctic Ozone Hole.

    ERIC Educational Resources Information Center

    Stolarski, Richard S.

    1988-01-01

    Discusses the Airborne Antarctic Ozone Experiment (1987) and the findings of the British Antarctic Survey (1985). Proposes two theories for the appearance of the hole in the ozone layer over Antarctica which appears each spring; air pollution and natural atmospheric shifts. Illustrates the mechanics of both. Supports worldwide chlorofluorocarbon…

  11. Antarctic news clips, 1991

    NASA Astrophysics Data System (ADS)

    1991-08-01

    Published stories are presented that sample a year's news coverage of Antarctica. The intent is to provide the U.S. Antarctic Program participants with a digest of current issues as presented by a variety of writers and popular publications. The subject areas covered include the following: earth science; ice studies; stratospheric ozone; astrophysics; life science; operations; education; antarctic treaty issues; and tourism

  12. The Antarctic Ice.

    ERIC Educational Resources Information Center

    Radok, Uwe

    1985-01-01

    The International Antarctic Glaciological Project has collected information on the East Antarctic ice sheet since 1969. Analysis of ice cores revealed climatic history, and radar soundings helped map bedrock of the continent. Computer models of the ice sheet and its changes over time will aid in predicting the future. (DH)

  13. The Antarctic Ice.

    ERIC Educational Resources Information Center

    Radok, Uwe

    1985-01-01

    The International Antarctic Glaciological Project has collected information on the East Antarctic ice sheet since 1969. Analysis of ice cores revealed climatic history, and radar soundings helped map bedrock of the continent. Computer models of the ice sheet and its changes over time will aid in predicting the future. (DH)

  14. Antarctic Meteorology and Climatology

    NASA Astrophysics Data System (ADS)

    King, J. C.; Turner, J.

    1997-07-01

    This book is a comprehensive survey of the climatology and meteorology of Antarctica. The first section of the book reviews the methods by which we can observe the Antarctic atmosphere and presents a synthesis of climatological measurements. In the second section, the authors consider the processes that maintain the observed climate, from large-scale atmospheric circulation to small-scale processes. The final section reviews our current knowledge of the variability of Antarctic climate and the possible effects of "greenhouse" warming. The authors stress links among the Antarctic atmosphere, other elements of the Antarctic climate system (oceans, sea ice and ice sheets), and the global climate system. This volume will be of greatest interest to meteorologists and climatologists with a specialized interest in Antarctica, but it will also appeal to researchers in Antarctic glaciology, oceanography and biology. Graduates and undergraduates studying physical geography, and the earth, atmospheric and environmental sciences will find much useful background material in the book.

  15. Promoters from a cold-adapted bacterium: definition of a consensus motif and molecular characterization of UP regulative elements.

    PubMed

    Duilio, Angela; Madonna, Stefania; Tutino, Maria Luisa; Pirozzi, Marinella; Sannia, Giovanni; Marino, Gennaro

    2004-04-01

    Although low-temperature tolerant micro-organisms were discovered long ago, limited information is still available on the transcription machinery in cold-adapted bacteria. This knowledge represents a necessary background for the investigation of the adaptation of gene-expression mechanisms at low temperatures. The recent development of a shuttle genetic system for the transformation of the cold-adapted Gram-negative bacterium Pseudoalteromonas haloplanktis strain TAC125 has made possible the isolation of the psychrophilic promoters described in this paper. TAC125 genomic DNA fragments were cloned in the shuttle vector and the promoter-containing recombinant clones were selected for their ability to express a promoter-less lacZ gene. The nucleotide sequence of several selected inserts and the transcription start points of the transcribed m-RNAs were determined. A promoter consensus sequence for Pseudoalteromonas haloplanktis TAC125 was proposed on the basis of a sequence comparison between the various active promoters. Furthermore, the identification and the functional characterization of two UP elements from this cold-adapted bacterium are also reported.

  16. The chemical cue tetrabromopyrrole from a biofilm bacterium induces settlement of multiple Caribbean corals

    PubMed Central

    Sneed, Jennifer M.; Sharp, Koty H.; Ritchie, Kimberly B.; Paul, Valerie J.

    2014-01-01

    Microbial biofilms induce larval settlement for some invertebrates, including corals; however, the chemical cues involved have rarely been identified. Here, we demonstrate the role of microbial biofilms in inducing larval settlement with the Caribbean coral Porites astreoides and report the first instance of a chemical cue isolated from a marine biofilm bacterium that induces complete settlement (attachment and metamorphosis) of Caribbean coral larvae. Larvae settled in response to natural biofilms, and the response was eliminated when biofilms were treated with antibiotics. A similar settlement response was elicited by monospecific biofilms of a single bacterial strain, Pseudoalteromonas sp. PS5, isolated from the surface biofilm of a crustose coralline alga. The activity of Pseudoalteromonas sp. PS5 was attributed to the production of a single compound, tetrabromopyrrole (TBP), which has been shown previously to induce metamorphosis without attachment in Pacific acroporid corals. In addition to inducing settlement of brooded larvae (P. astreoides), TBP also induced larval settlement for two broadcast-spawning species, Orbicella (formerly Montastraea) franksi and Acropora palmata, indicating that this compound may have widespread importance among Caribbean coral species. PMID:24850918

  17. The meroperon of a mercury-resistant Pseudoalteromonas haloplanktis strain isolated from Minamata Bay, Japan.

    PubMed

    Iohara, K; Iiyama, R; Nakamura, K; Silver, S; Sakai, M; Takeshita, M; Furukawa, K

    2001-09-01

    A mer operon of mercury-resistant Pseudoalteromonas haloplanktis strain M1, isolated from sea water of Minamata Bay, was cloned and analyzed. The mer genes were located in the chromosome and organized as merR-merT-merP-merC-merA-merD, the same order as that in Tn21. However, the orientation of the merR gene is the same as that of other mer genes (opposite direction to Tn21), and merR was cotranscribed with other mer genes, a pattern that has not been previously seen with mer determinants from other Gram-negative bacteria. Furthermore, the amino acid similarities of the corresponding mer gene products between those from strain M1 and Tn21 were unusually low.

  18. Production of the Bioactive Compounds Violacein and Indolmycin Is Conditional in a maeA Mutant of Pseudoalteromonas luteoviolacea S4054 Lacking the Malic Enzyme

    PubMed Central

    Thøgersen, Mariane S.; Delpin, Marina W.; Melchiorsen, Jette; Kilstrup, Mogens; Månsson, Maria; Bunk, Boyke; Spröer, Cathrin; Overmann, Jörg; Nielsen, Kristian F.; Gram, Lone

    2016-01-01

    It has previously been reported that some strains of the marine bacterium Pseudoalteromonas luteoviolacea produce the purple bioactive pigment violacein as well as the antibiotic compound indolmycin, hitherto only found in Streptomyces. The purpose of the present study was to determine the relative role of each of these two compounds as antibacterial compounds in P. luteoviolacea S4054. Using Tn10 transposon mutagenesis, a mutant strain that was significantly reduced in violacein production in mannose-containing substrates was created. Full genome analyses revealed that the vio-biosynthetic gene cluster was not interrupted by the transposon; instead the insertion was located to the maeA gene encoding the malic enzyme. Supernatant of the mutant strain inhibited Vibrio anguillarum and Staphylococcus aureus in well diffusion assays and in MIC assays at the same level as the wild type strain. The mutant strain killed V. anguillarum in co-culture experiments as efficiently as the wild type. Using UHPLC-UV/Vis analyses, we quantified violacein and indolmycin, and the mutant strain only produced 7–10% the amount of violacein compared to the wild type strain. In contrast, the amount of indolmycin produced by the mutant strain was about 300% that of the wild type. Since inhibition of V. anguillarum and S. aureus by the mutant strain was similar to that of the wild type, it is concluded that violacein is not the major antibacterial compound in P. luteoviolacea. We furthermore propose that production of violacein and indolmycin may be metabolically linked and that yet unidentified antibacterial compound(s) may be play a role in the antibacterial activity of P. luteoviolacea. PMID:27695447

  19. Purification and characterization of a bifunctional alginate lyase from Pseudoalteromonas sp. SM0524.

    PubMed

    Li, Jian-Wei; Dong, Sheng; Song, Jie; Li, Chun-Bo; Chen, Xiu-Lan; Xie, Bin-Bin; Zhang, Yu-Zhong

    2011-01-21

    An alginate lyase-producing bacterial strain, Pseudoalteromonas sp. SM0524, was screened from marine rotten kelp. In an optimized condition, the production of alginate lyase from Pseudoalteromonas sp. SM0524 reached 62.6 U/mL, suggesting that strain SM0524 is a good producer of alginate lyases. The bifunctional alginate lyase aly-SJ02 secreted by strain SM0524 was purified. Aly-SJ02 had an apparent molecular mass of 32 kDa. The optimal temperature and pH of aly-SJ02 toward sodium alginate was 50 °C and 8.5, respectively. The half life period of aly-SJ02 was 41 min at 40 °C and 20 min at 50 °C. Aly-SJ02 was most stable at pH 8.0. N-terminal sequence analysis suggested that aly-SJ02 may be an alginate lyase of polysaccharide lyase family 18. Aly-SJ02 showed activities toward both polyG (α-l-guluronic acid) and polyM (β-D-mannuronic acid), indicating that it is a bifunctional alginate lyase. Aly-SJ02 had lower K(m) toward polyG than toward polyM and sodium alginate. Thin layer chromatography and ESI-MS analyses showed that aly-SJ02 mainly released dimers and trimers from polyM and alginate, and trimers and tetramers from polyG, which suggests that aly-SJ02 may be a good tool to produce dimers and trimers from alginate.

  20. Antarctic accumulation seasonality.

    PubMed

    Sime, Louise C; Wolff, Eric W

    2011-11-09

    The resemblance of the orbitally filtered isotope signal from the past 340 kyr in Antarctic ice cores to Northern Hemisphere summer insolation intensity has been used to suggest that the northern hemisphere may drive orbital-scale global climate changes. A recent Letter by Laepple et al. suggests that, contrary to this interpretation, this semblance may instead be explained by weighting the orbitally controlled Antarctic seasonal insolation cycle with a static (present-day) estimate of the seasonal cycle of accumulation. We suggest, however, that both time variability in accumulation seasonality and alternative stable seasonality can markedly alter the weighted insolation signal. This indicates that, if the last 340 kyr of Antarctic accumulation has not always looked like the estimate of precipitation and accumulation seasonality made by Laepple et al., this particular accumulation weighting explanation of the Antarctic orbital-scale isotopic signal might not be robust.

  1. Screening of microorganisms from Antarctic surface water and cytotoxicity metabolites from Antarctic microorganisms.

    PubMed

    Zheng, Lanhong; Yang, Kangli; Liu, Jia; Sun, Mi; Zhu, Jiancheng; Lv, Mei; Kang, Daole; Wang, Wei; Xing, Mengxin; Li, Zhao

    2016-03-01

    The Antarctic is a potentially important library of microbial resources and new bioactive substances. In this study, microorganisms were isolated from surface water samples collected from different sites of the Antarctic. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay-based cytotoxicity-tracking method was used to identify Antarctic marine microorganism resources for antitumor lead compounds. The results showed that a total of 129 Antarctic microorganism strains were isolated. Twelve strains showed potent cytotoxic activities, among which a Gram-negative, rod-shaped bacterium, designated as N11-8 was further studied. Phylogenetic analysis based on 16S rRNA gene sequence showed that N11-8 belongs to the genus Bacillus. Fermented active products of N11-8 with molecular weights of 1-30 kDa had higher inhibitory effects on different cancaer cells, such as BEL-7402 human hepatocellular carcinoma cells, U251 human glioma cells, RKO human colon carcinoma cells, A549 human lung carcinoma cells, and MCF-7 human breast carcinoma cells. However, they displayed lower cytotoxicity against HFL1 human normal fibroblast lung cells. However, they displayed lower cytotoxicity against HFL1 human normal fibroblast lung cells. Microscopic observations showed that the fermented active products have inhibitory activity on BEL-7402 cells similar to that of mitomycin C. Further studies indicated that the fermented active products have high pH and high thermal stability. In conclusion, most strains isolated in this study may be developed as promising sources for the discovery of antitumor bioactive substances. The fermented active products of Antarctic marine Bacillus sp. N11- 8 are expected to be applied in the prevention and treatment of cancer.

  2. Complete Genome Sequence of Psychrobacter alimentarius PAMC 27889, a Psychrophile Isolated from an Antarctic Rock Sample

    PubMed Central

    Lee, Jaejin; Kwon, Miye; Yang, Jae Young; Woo, Jusun; Lee, Hong Kum; Hong, Soon Gyu

    2016-01-01

    Psychrobacter alimentarius PAMC 27889, a Gram-negative, psychrophilic bacterium, was isolated from an Antarctic rock sample. Here, we report the complete genome of P. alimentarius PAMC 27889, which has the nonmevalonate methylerythritol phosphate pathway of terpenoid biosynthesis and a complete gene cluster for benzoate degradation. PMID:27445386

  3. Genetic characterization of plasmid-mediated quinolone resistance gene qnrS2 in Pseudoalteromonas and Shewanella isolates from seawater.

    PubMed

    Zhao, Jing-Yi; Zhao, Shu-Mei; Mu, Xiao-Dong; Xiao, Zijun

    2016-12-23

    Three qnrS2-containing isolates of Pseudoalteromonas and Shewanella were collected from the seawater samples of Qingdao in China during 2014. They displayed resistance to ampicillin, ciprofloxacin, kanamycin, nalidixic acid and sulfamethoxazole. The qnrS2 genes were identified in the chromosomes of Pseudoalteromonas strain E8 and S16, and in a 140-kb plasmid in Shewanella strain S14, respectively. In addition, two copies of qnrS2 were identified in the strain E8. Sequence analyses revealed that there was an identical DNA segment located in the downstream of qnrS2 in strain S14 and E8, coding for a TetR transcriptional regulator, two putative integrases and a hypothetical protein. However, different genetic structures were identified in the upstream sequences: the terB gene associated with tellurite resistance in the strain S14, and a putative integron with dfrA6 and aadA13 gene cassettes or the Tn7-related gene complex tnsABC in the strain E8. In Pseudoalteromonas strain S16, qnrS2 was bracketed by the endonuclease I and III genes, and the electron transport complex rsxCDGE was located in the upstream sequences. This is the first report of two copies of the qnrS2 gene existing in one bacterial chromosome, and also the first identification of qnrS2 in Shewanella.

  4. Sugars in Antarctic aerosol

    NASA Astrophysics Data System (ADS)

    Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

    2015-10-01

    The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the "Mario Zucchelli" coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

  5. Genomic Analysis of a Marine Bacterium: Bioinformatics for Comparison, Evaluation, and Interpretation of DNA Sequences.

    PubMed

    Rekadwad, Bhagwan N; Gonzalez, Juan M; Khobragade, Chandrahasya N

    2016-01-01

    A total of five highly related strains of an unidentified marine bacterium were analyzed through their short genome sequences (AM260709-AM260713). Genome-to-Genome Distance (GGDC) showed high similarity to Pseudoalteromonas haloplanktis (X67024). The generated unique Quick Response (QR) codes indicated no identity to other microbial species or gene sequences. Chaos Game Representation (CGR) showed the number of bases concentrated in the area. Guanine residues were highest in number followed by cytosine. Frequency of Chaos Game Representation (FCGR) indicated that CC and GG blocks have higher frequency in the sequence from the evaluated marine bacterium strains. Maximum GC content for the marine bacterium strains ranged 53-54%. The use of QR codes, CGR, FCGR, and GC dataset helped in identifying and interpreting short genome sequences from specific isolates. A phylogenetic tree was constructed with the bootstrap test (1000 replicates) using MEGA6 software. Principal Component Analysis (PCA) was carried out using EMBL-EBI MUSCLE program. Thus, generated genomic data are of great assistance for hierarchical classification in Bacterial Systematics which combined with phenotypic features represents a basic procedure for a polyphasic approach on unambiguous bacterial isolate taxonomic classification.

  6. Genomic Analysis of a Marine Bacterium: Bioinformatics for Comparison, Evaluation, and Interpretation of DNA Sequences

    PubMed Central

    Khobragade, Chandrahasya N.

    2016-01-01

    A total of five highly related strains of an unidentified marine bacterium were analyzed through their short genome sequences (AM260709–AM260713). Genome-to-Genome Distance (GGDC) showed high similarity to Pseudoalteromonas haloplanktis (X67024). The generated unique Quick Response (QR) codes indicated no identity to other microbial species or gene sequences. Chaos Game Representation (CGR) showed the number of bases concentrated in the area. Guanine residues were highest in number followed by cytosine. Frequency of Chaos Game Representation (FCGR) indicated that CC and GG blocks have higher frequency in the sequence from the evaluated marine bacterium strains. Maximum GC content for the marine bacterium strains ranged 53-54%. The use of QR codes, CGR, FCGR, and GC dataset helped in identifying and interpreting short genome sequences from specific isolates. A phylogenetic tree was constructed with the bootstrap test (1000 replicates) using MEGA6 software. Principal Component Analysis (PCA) was carried out using EMBL-EBI MUSCLE program. Thus, generated genomic data are of great assistance for hierarchical classification in Bacterial Systematics which combined with phenotypic features represents a basic procedure for a polyphasic approach on unambiguous bacterial isolate taxonomic classification. PMID:27882328

  7. Antarctic Geoscience Initiative

    NASA Astrophysics Data System (ADS)

    Dalziel, Ian W. D.; Zimmerman, Herman B.

    Antarctia has recently been described as a continent surrounded by advice. The advice stems from growing realization of the Antarctic's importance in many aspects of globalscale Earth science. This article outlines a U.S. and international initiative to move solid-Earth scientists from an advisory role to one of acquiring new data bearing on the structure and evolution of the ice-covered Antarctic lithosphere.The initiative has marine, airborne, and terrestrial components; plans for all three are underway. Platforms exist for undertaking the work at sea and in the air, but land geophysical techniques need to be adapted to the Antarctic environment. An international workshop to plan modern over-ice geoscience transects will be convened in Washington, D.C., July 19-22 in conjunction with the 28th International Geological Congress (IGC).

  8. Antarctic terrestrial ecosystems

    SciTech Connect

    Walton, D.W.H.

    1987-01-01

    The Maritime and Continental Antarctic terrestrial ecosystems are considered in the context of environmental impacts - habitat destruction, alien introductions, and pollution. Four types of pollution are considered: nutrients, radionuclides, inert materials, and noxious chemicals. Their ability to recover from perturbation is discussed in the light of present scientific knowledge, and the methods used to control impacts are reviewed. It is concluded that techniques of waste disposal are still inadequate, adequate training in environmental and conservation principles for Antarctic personnel in many countries is lacking, and scientific investigations may be a much more serious threat than tourism to the integrity of these ecosystems. Some priorities crucial to future management are suggested.

  9. Draft Genome Sequence of Pseudoalteromonas sp. Strain ND6B, an Oil-Degrading Isolate from Eastern Mediterranean Sea Water Collected at a Depth of 1,210 Meters

    SciTech Connect

    Harris, Austin P.; Techtmann, Stephen M.; Stelling, Savannah C.; Utturkar, Sagar M.; Alshibli, Noor K.; Brown, Steven D.; Hazen, Terry C.

    2014-11-26

    We report the draft genome of Pseudoalteromonas sp. strain ND6B, which is able to grow with crude oil as a carbon source. Strain ND6B was isolated from eastern Mediterranean Sea deep water at a depth of 1,210 m. The genome of strain ND6B provides insight into the oil-degrading ability of the Pseudoalteromonas species.

  10. Filamentous phages prevalent in Pseudoalteromonas spp. confer properties advantageous to host survival in Arctic sea ice

    PubMed Central

    Yu, Zi-Chao; Chen, Xiu-Lan; Shen, Qing-Tao; Zhao, Dian-Li; Tang, Bai-Lu; Su, Hai-Nan; Wu, Zhao-Yu; Qin, Qi-Long; Xie, Bin-Bin; Zhang, Xi-Ying; Yu, Yong; Zhou, Bai-Cheng; Chen, Bo; Zhang, Yu-Zhong

    2015-01-01

    Sea ice is one of the most frigid environments for marine microbes. In contrast to other ocean ecosystems, microbes in permanent sea ice are space confined and subject to many extreme conditions, which change on a seasonal basis. How these microbial communities are regulated to survive the extreme sea ice environment is largely unknown. Here, we show that filamentous phages regulate the host bacterial community to improve survival of the host in permanent Arctic sea ice. We isolated a filamentous phage, f327, from an Arctic sea ice Pseudoalteromonas strain, and we demonstrated that this type of phage is widely distributed in Arctic sea ice. Growth experiments and transcriptome analysis indicated that this phage decreases the host growth rate, cell density and tolerance to NaCl and H2O2, but enhances its motility and chemotaxis. Our results suggest that the presence of the filamentous phage may be beneficial for survival of the host community in sea ice in winter, which is characterized by polar night, nutrient deficiency and high salinity, and that the filamentous phage may help avoid over blooming of the host in sea ice in summer, which is characterized by polar day, rich nutrient availability, intense radiation and high concentration of H2O2. Thus, while they cannot kill the host cells by lysing them, filamentous phages confer properties advantageous to host survival in the Arctic sea ice environment. Our study provides a foremost insight into the ecological role of filamentous phages in the Arctic sea ice ecosystem. PMID:25303713

  11. Filamentous phages prevalent in Pseudoalteromonas spp. confer properties advantageous to host survival in Arctic sea ice.

    PubMed

    Yu, Zi-Chao; Chen, Xiu-Lan; Shen, Qing-Tao; Zhao, Dian-Li; Tang, Bai-Lu; Su, Hai-Nan; Wu, Zhao-Yu; Qin, Qi-Long; Xie, Bin-Bin; Zhang, Xi-Ying; Yu, Yong; Zhou, Bai-Cheng; Chen, Bo; Zhang, Yu-Zhong

    2015-03-17

    Sea ice is one of the most frigid environments for marine microbes. In contrast to other ocean ecosystems, microbes in permanent sea ice are space confined and subject to many extreme conditions, which change on a seasonal basis. How these microbial communities are regulated to survive the extreme sea ice environment is largely unknown. Here, we show that filamentous phages regulate the host bacterial community to improve survival of the host in permanent Arctic sea ice. We isolated a filamentous phage, f327, from an Arctic sea ice Pseudoalteromonas strain, and we demonstrated that this type of phage is widely distributed in Arctic sea ice. Growth experiments and transcriptome analysis indicated that this phage decreases the host growth rate, cell density and tolerance to NaCl and H2O2, but enhances its motility and chemotaxis. Our results suggest that the presence of the filamentous phage may be beneficial for survival of the host community in sea ice in winter, which is characterized by polar night, nutrient deficiency and high salinity, and that the filamentous phage may help avoid over blooming of the host in sea ice in summer, which is characterized by polar day, rich nutrient availability, intense radiation and high concentration of H2O2. Thus, while they cannot kill the host cells by lysing them, filamentous phages confer properties advantageous to host survival in the Arctic sea ice environment. Our study provides a foremost insight into the ecological role of filamentous phages in the Arctic sea ice ecosystem.

  12. D-Phenylalanine inhibits biofilm development of a marine microbe, Pseudoalteromonas sp. SC2014.

    PubMed

    Li, Ee; Wu, Jiajia; Wang, Peng; Zhang, Dun

    2016-09-01

    D-Amino acids have been reported to be able to inhibit biofilm formation or disperse existing biofilms of many microbes; in some cases this is due to growth inhibition as an unspecific effect. In this work, six different D-amino acids were tested for their inhibitory effects on biofilm development and bacterial growth of Pseudoalteromonas sp. SC2014, a marine microbe involved in microbiologically influenced corrosion (MIC). Experimental results indicated that D-phenylalanine (D-Phe) inhibited biofilm formation effectively at concentrations that did not affect cell growth, whereas the other D-amino acids either showed little effect or inhibited biofilm formation while inhibiting bacterial growth. Further studies found that D-Phe could inhibit bacterial accumulation on the surface of 316L stainless steel, and prevent bacteria from forming a multilayer biofilm. It was also suggested that D-Phe could promote the disassembly of an established multilayer biofilm but have little effect on the remaining monolayer adherent cells. For the first time, it was found that a D-amino acid could effectively inhibit biofilm formation of an MIC-involved microbe. This might supply a new insight into how MIC could be mitigated. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Glutathionylation of the iron superoxide dismutase from the psychrophilic eubacterium Pseudoalteromonas haloplanktis.

    PubMed

    Castellano, Immacolata; Ruocco, Maria Rosaria; Cecere, Francesca; Di Maro, Antimo; Chambery, Angela; Michniewicz, Andzelika; Parlato, Giuseppe; Masullo, Mariorosario; De Vendittis, Emmanuele

    2008-05-01

    Our previous work showed that the adduct between beta-mercaptoethanol and the single cysteine residue (Cys57) in superoxide dismutase from the psychrophilic eubacterium Pseudoalteromonas haloplanktis (PhSOD) reduces the enzyme inactivation by peroxynitrite. In this work, immunoblotting experiments prove that peroxynitrite inactivation of PhSOD involves formation of nitrotyrosine residue(s). In order to study the role of Cys57 as a redox-sensor residue modifiable by cellular thiols, a recombinant PhSOD and two Cys57 mutants were produced and characterized. Recombinant and mutant enzymes share similar activity and peroxynitrite inactivation, but different reactivity towards three glutathione forms. Indeed, oxidized glutathione and S-nitrosoglutathione, but reduced glutathione, lead to S-glutathionylation of recombinant PhSOD. This new covalent modification for a Fe-SOD does not occur in both Cys57 mutants, thus indicating that its target is Cys57. Moreover, mass spectrometry analysis confirmed that S-glutathionylation of Cys57 takes place also with endogenous PhSOD. Formation of this mixed disulfide in PhSOD protects the enzyme from tyrosine nitration and peroxynitrite inactivation. PhSOD undergoes S-glutathionylation during its overproduction in E. coli cells and in a growing culture of P. haloplanktis. In both cases the extent of glutathionylated PhSOD is enhanced upon cell exposure to oxidative agents. We suggest that S-glutathionylation of PhSOD could represent a further cold-adaptation strategy to improve the antioxidant cellular defence mechanism.

  14. Identification of a Marine Agarolytic Pseudoalteromonas Isolate and Characterization of Its Extracellular Agarase

    PubMed Central

    Vera, Jorge; Alvarez, Raul; Murano, Erminio; Slebe, Juan Carlos; Leon, Oscar

    1998-01-01

    The phenotypic and agarolytic features of an unidentified marine bacteria that was isolated from the southern Pacific coast was investigated. The strain was gram negative, obligately aerobic, and polarly flagellated. On the basis of several phenotypic characters and a phylogenetic analysis of the genes coding for the 16S rRNA, this strain was identified as Pseudoalteromonas antarctica strain N-1. In solid agar, this isolate produced a diffusible agarase that caused agar softening around the colonies. An extracellular agarase was purified by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography on DEAE-cellulose. The purified protein was determined to be homogeneous on the basis of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it had a molecular mass of 33 kDa. The enzyme hydrolyzed the β-1,4-glycosydic linkages of agar, yielding neoagarotetraose and neoagarohexaose as the main products, and exhibited maximal activity at pH 7. The enzyme was stable at temperatures up to 30°C, and its activity was not affected by salt concentrations up to 0.5 M NaCl. PMID:9797294

  15. Anti-biofilm activity of Pseudoalteromonas flavipulchra SktPp1 against Serratia marcescens SMJ-11

    NASA Astrophysics Data System (ADS)

    Iqbal, Faiq; Usup, Gires; Ahmad, Asmat

    2015-09-01

    This study aimed to examine the anti-biofilm activity of Pseudoalteromonas flavipulchra SktPp1 crude extract against the biofilm producer, Serratia marcescens. The crude extract of P. flavipulchra SktPp1 was extracted with ethyl acetate. The sub-minimum inhibitory concentration (MIC), 0.1 mg/ml, has been used in this study. The anti-biofilm activity of P. flavipulchra SktPp1 crude extract was assessed against the biofilm of S. marcescens using the crystal violet assay. The growth curve has been used as the indicator of the effect of crude extracts to bacterial growth. The sub-MIC crude extract was tested against two of S. marcescens virulence factors, including the swarming ability and production of prodigiosin using the swarming assay and prodigiosin assay. The growth curves of S. marcescens indicated that the sub-MIC concentration of crude extract did not affect the growth of S. marcescens. The production of prodigiosin was reduced by 44%. The diameter of the swarming area was reduced from 8.7 cm to 0.8 cm. The sub-MIC crude extract inhibits 26.9% of the biofilm production in S. marcescens. This crude extract lost its activity at 50°C and above. In conclusion, crude extract of P. flavipulchra SktPp1 has the ability to inhibit S. marcescens SMJ-11 biofilm formation.

  16. Purification and biochemical characterization of an alkaline protease from marine bacteria Pseudoalteromonas sp. 129-1.

    PubMed

    Wu, Shimei; Liu, Ge; Zhang, Dechao; Li, Chaoxu; Sun, Chaomin

    2015-12-01

    An extracellular alkaline protease produced by marine bacteria strain Pseudoalteromonas sp. 129-1 was purified by ammonium sulphate precipitation, anion exchange chromatography, and gel filtration. The purity of the protease was confirmed by SDS-PAGE and molecular mass was estimated to be 35 kDa. The protease maintained considerable activity and stability at a wide temperature range of 10-60 °C and pH range of 6-11, and optimum activity was detected at temperature of 50 °C and pH of 8. Metallo-protease inhibitor, EDTA, had no inhibitory effect on protease activity even at concentration up to 15 mM, whereas 15 mM PMSF, a common serine protease inhibitor, greatly inactivated the protease. The high stability of the protease in the presence of surfactants (SDS, Tween 80, and Triton X-100), oxidizing agent H(2)O(2), and commercial detergents was observed. Moreover, the protease was tolerant to most of the tested organic solvents, and saline tolerant up to 30%. Interestingly, biofilm of Pseudomonas aeruginosa PAO1 was greatly reduced by 0.01 mg ml(-1) of the protease, and nearly completely abolished with the concentration of 1 mg ml(-1). Collectively, the protease showed valuable feathers as an additive in laundry detergent and non-toxic anti-biofilm agent.

  17. Cellulase production from Pseudoalteromonas sp. NO3 isolated from the sea squirt Halocynthia rorentzi.

    PubMed

    Kim, Duwoon; Baik, Keun Sik; Park, Seong Chan; Kim, Seon-Jun; Shin, Tai-Sun; Jung, Sung-Joo; Oh, Myung-Joo; Seong, Chi Nam

    2009-11-01

    Pseudoalteromonas sp. NO3 was isolated from the hemolymph of diseased sea squirts (Halocynthia rorentzi) with symptoms of soft tunic syndrome. The strain was found to produce an extracellular cellulase (CelY) that consisted of a 1,476 bp open reading frame encoding 491 amino acid residues with an approximate molecular mass of 52 kDa. Homologies of the deduced amino acid sequence of celY with the products of the celA, celX, celG and cel5Z genes were 92.6, 93.3, 92.6, and 59.1%, respectively. Additionally, CelY had 50-80% remnant catalytic activity at temperatures of 10-20 degrees C. Highest carboxymethyl cellulose (CMC) hydrolysis was observed at pH 8.0 and 40 degrees C. CMC activity was determined by zymogram active staining and different degraded product profiles for CelY were obtained when cellotetraose, cellopentaose, and CMC were used as substrates. This study identified a transglycosylation activity in CelY that allows the enzyme to digest G4 to G2 and G3 without the production of G1.

  18. Characterization of an arylsulfatase from a mutant library of Pseudoalteromonas carrageenovora arylsulfatase.

    PubMed

    Zhu, Yanbing; Liu, Han; Qiao, Chaochao; Li, Lijun; Jiang, Zedong; Xiao, Anfeng; Ni, Hui

    2017-03-01

    A library of Pseudoalteromonas carrageenovora arylsulfatase mutants was constructed by introducing random mutagenesis using error-prone PCR. After screening, one mutant strain was obtained whose arylsulfatase had improved thermal stability. Protein sequence analysis revealed one amino acid substitution of H260L. The mutant arylsulfatase (named H260L) retained higher residual activity than wild-type enzyme (named WT) after incubation at 45, 50, 55 and 60°C for 60min. Thermal inactivation analysis showed that the half-life (t1/2) value at 55°C for H260L was 40.6min, while that of WT was 9.1min. When p-nitrophenyl sulfate was used as a substrate, the optimal reaction temperature and pH for the mutant enzyme were 55°C and pH 8.0, respectively. H260L was stable over the pH range of 6.0-9.0. Inhibition assay with EDTA indicated that metal ions play an important role during the catalytic process of the mutant enzyme. The desulfation ratio against agar of Gracilaria lemaneiformis was 82%.

  19. Accelerator analysis of tributyltin adsorbed onto the surface of a tributyltin resistant marine Pseudoalteromonas sp. cell.

    PubMed

    Mimura, Haruo; Sato, Ryusei; Sasaki, Yu; Furuyama, Yuichi; Taniike, Akira; Yoshida, Kazutoshi; Kitamura, Akira

    2008-10-01

    Tributyltin (TBT) released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship's ballast water. The isolate (10(9.3 +/- 0.2) colony-forming units mL(-1)) adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 10(8.2). The value was reduced to about one-fifth when the lysozyme-treated cells were used. The surface of ethanol treated cells became rough, but the capacity of TBT adsorption was the same as that for native cells. These results indicate that the function of the cell surface, rather than that structure, plays an important role to the adsorption of TBT. The adsorption state of TBT seems to be multi-layer when the number of more than 10(6.8) TBT molecules is adsorbed by a single cell.

  20. Accelerator Analysis of Tributyltin Adsorbed onto the Surface of a Tributyltin Resistant Marine Pseudoalteromonas sp. Cell

    PubMed Central

    Mimura, Haruo; Sato, Ryusei; Sasaki, Yu; Furuyama, Yuichi; Taniike, Akira; Yoshida, Kazutoshi; Kitamura, Akira

    2008-01-01

    Tributyltin (TBT) released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship’s ballast water. The isolate (109.3 ± 0.2 colony-forming units mL−1) adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 108.2. The value was reduced to about one-fifth when the lysozyme-treated cells were used. The surface of ethanol treated cells became rough, but the capacity of TBT adsorption was the same as that for native cells. These results indicate that the function of the cell surface, rather than that structure, plays an important role to the adsorption of TBT. The adsorption state of TBT seems to be multi-layer when the number of more than 106.8 TBT molecules is adsorbed by a single cell. PMID:19325731

  1. Isolation and identification of a bacterium from marine shrimp digestive tract: A new degrader of starch and protein

    NASA Astrophysics Data System (ADS)

    Li, Jiqiu; Tan, Beiping; Mai, Kangsen

    2011-09-01

    It is a practical approach to select candidate probiotic bacterial stains on the basis of their special traits. Production of digestive enzyme was used as a trait to select a candidate probiotic bacterial strain in this study. In order to select a bacterium with the ability to degrade both starch and protein, an ideal bacterial strain STE was isolated from marine shrimp ( Litopenaeus vannamei) intestines by using multiple selective media. The selected isolate STE was identified on the basis of its morphological, physiological, and biochemical characteristics as well as molecular analyses. Results of degradation experiments confirmed the ability of the selected isolate to degrade both starch and casein. The isolate STE was aerobic, Gram-negative, rod-shaped, motile and non-spore-forming, and had catalase and oxidase activities but no glucose fermentation activity. Among the tested carbon/nitrogen sources, only Tween40, alanyl-glycine, aspartyl-glycine, and glycyl-l-glutamic acid were utilized by the isolate STE. Results of homology comparison analyses of the 16S rDNA sequences showed that the isolate STE had a high similarity to several Pseudoalteromonas species and, in the phylogenetic tree, grouped with P. ruthenica with maximum bootstrap support (100%). In conclusion, the isolate STE was characterized as a novel strain belonging to the genus Pseudoalteromonas. This study provides a further example of a probiotic bacterial strain with specific characteristics isolated from the host gastrointestinal tract.

  2. Influence of subtilisin on the adhesion of a marine bacterium which produces mainly proteins as extracellular polymers.

    PubMed

    Leroy, C; Delbarre, C; Ghillebaert, F; Compere, C; Combes, D

    2008-09-01

    The nature of exopolymers involved in the adhesion of a marine biofilm-forming bacterium Pseudoalteromonas sp. D41 was investigated to evaluate and understand the antifouling potential of subtilisin. The exopolymers of D41 produced by fermentation were analysed by FTIR and SDS-PAGE showing the presence of polysaccharides, glycoproteins and proteins. A high content of proteins was detected both in soluble and capsular fractions. The microscopic observations of fluorescamine and calcofluor stained adhered D41 indicated mainly the presence of proteins in exopolymers produced during adhesion. Subtilisin, the broad spectrum protease, tested in natural sea water and in polystyrene microplates showed that antifouling activity was higher in the prevention of bacterial adhesion than in the detachment of adhered D41 cells. Overall, these results demonstrate the involvement of proteins in Pseudoalteromonas sp. D41 adhesion and confirm the high antifouling potential of subtilisin. This study emphasizes the major role of proteins instead of polysaccharides, thus extending our knowledge regarding the nature of extracellular polymers involved in bacterial adhesion. Furthermore, the high antifouling potential of subtilisin evaluated in the very first stages of fouling, bacterial adhesion, could lead to less toxic compounds than organometallic compounds in antifouling paint.

  3. Diagnosing Antarctic Fog

    NASA Astrophysics Data System (ADS)

    Lazzara, M. A.

    2010-07-01

    Fog affects aviation and other logistical operations in the Antarctic; nevertheless limited studies have been conducted to understand fog behavior in this part of the world. A study has been conducted in the Ross Island region of Antarctica, the location of McMurdo Station and Scott Base - the main stations of the United States and New Zealand Antarctic programs, respectively. Using tools such as multi-channel satellites observations and supported by in situ radiosonde and ground-based automatic weather station observations, combined with back trajectory and mesoscale numerical models, discover that austral summer fog events are "advective" in temperament. The diagnosis finds a primary source region from the southeast over the Ross Ice Shelf (over 72% of the cases studied) while a minority of cases point toward a secondary fog source region to the north along the Scott Coast of the Ross Sea with influences from the East Antarctic Plateau. Part of this examination confirms existing anecdotes from forecasters and weather observers, while refuting others about fog and its behavior in this environment. This effort marks the beginning of our understanding of Antarctic fog behavior.

  4. Antarctic Atmospheric Infrasound.

    DTIC Science & Technology

    1981-11-30

    A summary is given of the project chronology and the reports describing our research in Antarctic Atmospheric infrasound. Analysis of selected infrasonic signals is discussed and a list is given of all infrasonic waves received on the digital system with correlation coefficient greater than 0.6. (Author)

  5. Life-Style and Genome Structure of Marine Pseudoalteromonas Siphovirus B8b Isolated from the Northwestern Mediterranean Sea

    SciTech Connect

    Lara, Elena; Holmfeldt, Karin; Solonenko, Natalie; Sà, Elisabet Laia; Ignacio-Espinoza, J. Cesar; Cornejo-Castillo, Francisco M.; Verberkmoes, Nathan C.; Vaqué, Dolors; Sullivan, Matthew B.; Acinas, Silvia G.; Kellogg, Christina A.

    2015-01-14

    Marine viruses (phages) alter bacterial diversity and evolution with impacts on marine biogeochemical cycles, and yet few well-developed model systems limit opportunities for hypothesis testing. We isolate phage B8b from the Mediterranean Sea using Pseudoalteromonas sp. QC-44 as a host and characterize it using myriad techniques. Morphologically, phage B8b was classified as a member of the Siphoviridae family. One-step growth analyses showed that this siphovirus had a latent period of 70 min and released 172 new viral particles per cell. In the host range analysis against 89 bacterial host strains revealed that phage B8b infected 3 Pseudoalteromonas strains (52 tested, >99.9% 16S rRNA gene nucleotide identity) and 1 non-Pseudoaltermonas strain belonging to Alteromonas sp. (37 strains from 6 genera tested), which helps bound the phylogenetic distance possible in a phage-mediated horizontal gene transfer event. The Pseudoalteromonas phage B8b genome size was 42.7 kb, with clear structural and replication modules where the former were delineated leveraging identification of 16 structural genes by virion structural proteomics, only 4 of which had any similarity to known structural proteins. In nature, this phage was common in coastal marine environments in both photic and aphotic layers (found in 26.5% of available viral metagenomes), but not abundant in any sample (average per sample abundance was 0.65% of the reads). Together these data improve our understanding of siphoviruses in nature, and provide foundational information for a new 'rare virosphere' phage-host model system.

  6. Life-Style and Genome Structure of Marine Pseudoalteromonas Siphovirus B8b Isolated from the Northwestern Mediterranean Sea

    DOE PAGES

    Lara, Elena; Holmfeldt, Karin; Solonenko, Natalie; ...

    2015-01-14

    Marine viruses (phages) alter bacterial diversity and evolution with impacts on marine biogeochemical cycles, and yet few well-developed model systems limit opportunities for hypothesis testing. We isolate phage B8b from the Mediterranean Sea using Pseudoalteromonas sp. QC-44 as a host and characterize it using myriad techniques. Morphologically, phage B8b was classified as a member of the Siphoviridae family. One-step growth analyses showed that this siphovirus had a latent period of 70 min and released 172 new viral particles per cell. In the host range analysis against 89 bacterial host strains revealed that phage B8b infected 3 Pseudoalteromonas strains (52 tested,more » >99.9% 16S rRNA gene nucleotide identity) and 1 non-Pseudoaltermonas strain belonging to Alteromonas sp. (37 strains from 6 genera tested), which helps bound the phylogenetic distance possible in a phage-mediated horizontal gene transfer event. The Pseudoalteromonas phage B8b genome size was 42.7 kb, with clear structural and replication modules where the former were delineated leveraging identification of 16 structural genes by virion structural proteomics, only 4 of which had any similarity to known structural proteins. In nature, this phage was common in coastal marine environments in both photic and aphotic layers (found in 26.5% of available viral metagenomes), but not abundant in any sample (average per sample abundance was 0.65% of the reads). Together these data improve our understanding of siphoviruses in nature, and provide foundational information for a new 'rare virosphere' phage-host model system.« less

  7. Emulsifying and Metal Ion Binding Activity of a Glycoprotein Exopolymer Produced by Pseudoalteromonas sp. Strain TG12▿

    PubMed Central

    Gutierrez, Tony; Shimmield, Tracy; Haidon, Cheryl; Black, Kenny; Green, David H.

    2008-01-01

    In this study, we describe the isolation and characterization of a new exopolymer that exhibits high emulsifying activities against a range of oil substrates and demonstrates a differential capacity to desorb various mono-, di-, and trivalent metal species from marine sediment under nonionic and seawater ionic-strength conditions. This polymer, PE12, was produced by a new isolate, Pseudoalteromonas sp. strain TG12 (accession number EF685033), during growth in a modified Zobell's 2216 medium amended with 1% glucose. Chemical and chromatographic analysis showed it to be a high-molecular-mass (>2,000 kDa) glycoprotein composed of carbohydrate (32.3%) and protein (8.2%). PE12 was notable in that it contained xylose as the major sugar component at unusually high levels (27.7%) not previously reported for a Pseudoalteromonas exopolymer. The polymer was shown to desorb various metal species from marine sediment—a function putatively conferred by its high content of uronic acids (28.7%). Seawater ionic strength (simulated using 0.6 M NaCl), however, caused a significant reduction in PE12's ability to desorb the sediment-adsorbed metals. These results demonstrate the importance of electrolytes, a physical parameter intrinsic of seawater, in influencing the interaction of microbial exopolymers with metal ions. In summary, PE12 may represent a new class of Pseudoalteromonas exopolymer with a potential for use in biotechnological applications as an emulsifying or metal-chelating agent. In addition to the biotechnological potential of these findings, the ecological aspects of this and related bacterial exopolymers in marine environments are also discussed. PMID:18552188

  8. Life-style and genome structure of marine Pseudoalteromonas siphovirus B8b isolated from the northwestern Mediterranean Sea.

    PubMed

    Lara, Elena; Holmfeldt, Karin; Solonenko, Natalie; Sà, Elisabet Laia; Ignacio-Espinoza, J Cesar; Cornejo-Castillo, Francisco M; Verberkmoes, Nathan C; Vaqué, Dolors; Sullivan, Matthew B; Acinas, Silvia G

    2015-01-01

    Marine viruses (phages) alter bacterial diversity and evolution with impacts on marine biogeochemical cycles, and yet few well-developed model systems limit opportunities for hypothesis testing. Here we isolate phage B8b from the Mediterranean Sea using Pseudoalteromonas sp. QC-44 as a host and characterize it using myriad techniques. Morphologically, phage B8b was classified as a member of the Siphoviridae family. One-step growth analyses showed that this siphovirus had a latent period of 70 min and released 172 new viral particles per cell. Host range analysis against 89 bacterial host strains revealed that phage B8b infected 3 Pseudoalteromonas strains (52 tested, >99.9% 16S rRNA gene nucleotide identity) and 1 non-Pseudoaltermonas strain belonging to Alteromonas sp. (37 strains from 6 genera tested), which helps bound the phylogenetic distance possible in a phage-mediated horizontal gene transfer event. The Pseudoalteromonas phage B8b genome size was 42.7 kb, with clear structural and replication modules where the former were delineated leveraging identification of 16 structural genes by virion structural proteomics, only 4 of which had any similarity to known structural proteins. In nature, this phage was common in coastal marine environments in both photic and aphotic layers (found in 26.5% of available viral metagenomes), but not abundant in any sample (average per sample abundance was 0.65% of the reads). Together these data improve our understanding of siphoviruses in nature, and provide foundational information for a new 'rare virosphere' phage-host model system.

  9. Life-Style and Genome Structure of Marine Pseudoalteromonas Siphovirus B8b Isolated from the Northwestern Mediterranean Sea

    PubMed Central

    Lara, Elena; Holmfeldt, Karin; Solonenko, Natalie; Sà, Elisabet Laia; Ignacio-Espinoza, J. Cesar; Cornejo-Castillo, Francisco M.; Verberkmoes, Nathan C.; Vaqué, Dolors; Sullivan, Matthew B.; Acinas, Silvia G.

    2015-01-01

    Marine viruses (phages) alter bacterial diversity and evolution with impacts on marine biogeochemical cycles, and yet few well-developed model systems limit opportunities for hypothesis testing. Here we isolate phage B8b from the Mediterranean Sea using Pseudoalteromonas sp. QC-44 as a host and characterize it using myriad techniques. Morphologically, phage B8b was classified as a member of the Siphoviridae family. One-step growth analyses showed that this siphovirus had a latent period of 70 min and released 172 new viral particles per cell. Host range analysis against 89 bacterial host strains revealed that phage B8b infected 3 Pseudoalteromonas strains (52 tested, >99.9% 16S rRNA gene nucleotide identity) and 1 non-Pseudoaltermonas strain belonging to Alteromonas sp. (37 strains from 6 genera tested), which helps bound the phylogenetic distance possible in a phage-mediated horizontal gene transfer event. The Pseudoalteromonas phage B8b genome size was 42.7 kb, with clear structural and replication modules where the former were delineated leveraging identification of 16 structural genes by virion structural proteomics, only 4 of which had any similarity to known structural proteins. In nature, this phage was common in coastal marine environments in both photic and aphotic layers (found in 26.5% of available viral metagenomes), but not abundant in any sample (average per sample abundance was 0.65% of the reads). Together these data improve our understanding of siphoviruses in nature, and provide foundational information for a new ‘rare virosphere’ phage–host model system. PMID:25587991

  10. Draft Genome Sequence of Pseudomonas sp. Strain Ant30-3, a Psychrotolerant Bacterium with Biodegradative Attribute Isolated from Antarctica

    PubMed Central

    Basu, Malay K.; Crowley, Michael; Aislabie, Jackie; Bej, Asim K.

    2014-01-01

    Pseudomonas sp. strain Ant30-3, isolated from fuel-contaminated Antarctic soil, exhibited distinctive psychrotolerant attributes and the potential for degrading aromatic hydrocarbon compounds at cold temperatures. We report here the 6.14-Mb draft genome of Ant30-3, which will provide insights into the genomic basis for the psychrotolerant and biodegradative properties of this bacterium. PMID:24903870

  11. Differences between Antarctic and non-Antarctic meteorites: An assessment

    SciTech Connect

    Koeberl, C. ); Cassidy, W.A. )

    1991-01-01

    The discovery of a statistically significant number of meteorites in Antarctica over the past 20 years has posed many questions. One of the most intriguing suggestions that came up during the study of the Antarctic samples was that there might be a difference between the parent populations of Antarctic and non-Antarctic samples was that there might be a difference between the parent populations of Antarctic and non-Antarctic meteorites. This interpretation was put forward after the detection of a significant difference in the abundances of volatile and mobile trace elements in H, L, and C chondrites and achondrites. Other major differences include the occurrence of previously rare or unknown meteorites, different meteorite-type frequencies, petrographic characteristics, oxygen isotopic compositions, and smaller average masses. Not all differences between the Antarctic and non-Antarctic meteorite populations can be explained by weathering, pairing, or different collection procedures. Variable trace element abundances and distinct differences in the thermal history and thermoluminescence characteristics have to be interpreted as being pre-terrestrial in origin. Such differences imply the existence of meteoroid streams, whose existence poses problems in the framework of our current knowledge of celestial mechanics. In this paper we summarize the contributions in this series and provide a review of the current state of the question for the reality and cause of differences between Antarctic and non-Antarctic meteorites.

  12. The Antarctic Planet Interferometer

    NASA Technical Reports Server (NTRS)

    Swain, Mark R.; Walker, Christopher K.; Traub, Wesley A.; Storey, John W.; CoudeduForesto, Vincent; Fossat, Eric; Vakili, Farrok; Stark, Anthony A.; Lloyd, James P.; Lawson, Peter R.; hide

    2004-01-01

    The Antarctic Planet Interferometer is an instrument concept designed to detect and characterize extrasolar planets by exploiting the unique potential of the best accessible site on earth for thermal infrared interferometry. High-precision interferometric techniques under development for extrasolar planet detection and characterization (differential phase, nulling and astrometry) all benefit substantially from the slow, low-altitude turbulence, low water vapor content, and low temperature found on the Antarctic plateau. At the best of these locations, such as the Concordia base being developed at Dome C, an interferometer with two-meter diameter class apertures has the potential to deliver unique science for a variety of topics, including extrasolar planets, active galactic nuclei, young stellar objects, and protoplanetary disks.

  13. Antarctic science preserve polluted

    NASA Astrophysics Data System (ADS)

    Simarski, Lynn Teo

    Geophysicists are alarmed at the electromagnetic pollution of a research site in the Antarctic specifically set aside to study the ionosphere and magnetosphere. A private New Zealand communications company called Telecom recently constructed a satellite ground station within the boundaries of this Site of Special Scientific Interest (SSSI), protected since the mid-1970s. The placement of a commercial facility within this site sets an ominous precedent not only for the sanctity of other SSSIs, but also for Specially Protected Areas—preserves not even open to scientific research, such as certain penguin rookeries.The roughly rectangular, one-by-one-half mile site, located at Arrival Heights not far from McMurdo Station, is one of a number of areas protected under the Antarctic treaty for designated scientific activities. Many sites are set aside for geological or biological research, but this is the only one specifically for physical science.

  14. Viruses in Antarctic lakes

    NASA Technical Reports Server (NTRS)

    Kepner, R. L. Jr; Wharton, R. A. Jr; Suttle, C. A.; Wharton RA, J. r. (Principal Investigator)

    1998-01-01

    Water samples collected from four perennially ice-covered Antarctic lakes during the austral summer of 1996-1997 contained high densities of extracellular viruses. Many of these viruses were found to be morphologically similar to double-stranded DNA viruses that are known to infect algae and protozoa. These constitute the first observations of viruses in perennially ice-covered polar lakes. The abundance of planktonic viruses and data suggesting substantial production potential (relative to bacteria] secondary and photosynthetic primary production) indicate that viral lysis may be a major factor in the regulation of microbial populations in these extreme environments. Furthermore, we suggest that Antarctic lakes may be a reservoir of previously undescribed viruses that possess novel biological and biochemical characteristics.

  15. Viruses in Antarctic lakes

    NASA Technical Reports Server (NTRS)

    Kepner, R. L. Jr; Wharton, R. A. Jr; Suttle, C. A.; Wharton RA, J. r. (Principal Investigator)

    1998-01-01

    Water samples collected from four perennially ice-covered Antarctic lakes during the austral summer of 1996-1997 contained high densities of extracellular viruses. Many of these viruses were found to be morphologically similar to double-stranded DNA viruses that are known to infect algae and protozoa. These constitute the first observations of viruses in perennially ice-covered polar lakes. The abundance of planktonic viruses and data suggesting substantial production potential (relative to bacteria] secondary and photosynthetic primary production) indicate that viral lysis may be a major factor in the regulation of microbial populations in these extreme environments. Furthermore, we suggest that Antarctic lakes may be a reservoir of previously undescribed viruses that possess novel biological and biochemical characteristics.

  16. Antarctic Meteorite Newsletter

    NASA Technical Reports Server (NTRS)

    Lindstrom, Marilyn

    2000-01-01

    This newsletter contains something for everyone! It lists classifications of about 440 meteorites mostly from the 1997 and 1998 ANSMET (Antarctic Search for Meteorites) seasons. It also gives descriptions of about 45 meteorites of special petrologic type. These include 1 iron, 17 chondrites (7 CC, 1 EC, 9 OC) and 27 achondrites (25 HED, UR). Most notable are an acapoloite (GRA98028) and an olivine diogenite (GRA98108).

  17. Thermoluminescence and Antarctic meteorites

    NASA Technical Reports Server (NTRS)

    Sears, D. W. G.; Hasan, F. A.

    1986-01-01

    The level of natural thermoluminescence (TL) in meteorites is the result of competition between build-up, due to exposure to cosmic radiation, and thermal decay. Antarctic meteorites tend to have lower natural TL than non-Antarctic meteorites because of their generally larger terrestrial ages. However, since a few observed falls have low TL due to a recent heating event, such as passage within approximately 0.7 astronomical units of the Sun, this could also be the case for some Antarctic meteorites. Dose rate variations due to shielding, heating during atmospheric passage, and anomalous fading also cause natural TL variations, but the effects are either relatively small, occur infrequently, or can be experimentally circumvented. The TL sensitivity of meteorites reflects the abundance and nature of the feldspar. Thus intense shock, which destroys feldspar, causes the TL sensitivity to decrease by 1 to 2 orders of magnitude, while metamorphism, which generates feldspar through the devitrification of glass, causes TL sensitivity to increase by a factor of approximately 10000. The TL-metamorphism relationship is particularly strong for the lowest levels of metamorphism. The order-disorder transformation in feldspar also affect the TL emission characteristics and thus TL provides a means of paleothermometry.

  18. Antarctic Photochemistry: Uncertainty Analysis

    NASA Technical Reports Server (NTRS)

    Stewart, Richard W.; McConnell, Joseph R.

    1999-01-01

    Understanding the photochemistry of the Antarctic region is important for several reasons. Analysis of ice cores provides historical information on several species such as hydrogen peroxide and sulfur-bearing compounds. The former can potentially provide information on the history of oxidants in the troposphere and the latter may shed light on DMS-climate relationships. Extracting such information requires that we be able to model the photochemistry of the Antarctic troposphere and relate atmospheric concentrations to deposition rates and sequestration in the polar ice. This paper deals with one aspect of the uncertainty inherent in photochemical models of the high latitude troposphere: that arising from imprecision in the kinetic data used in the calculations. Such uncertainties in Antarctic models tend to be larger than those in models of mid to low latitude clean air. One reason is the lower temperatures which result in increased imprecision in kinetic data, assumed to be best characterized at 298K. Another is the inclusion of a DMS oxidation scheme in the present model. Many of the rates in this scheme are less precisely known than are rates in the standard chemistry used in many stratospheric and tropospheric models.

  19. [Helminths of Antarctic fishes].

    PubMed

    Rocka, Anna

    2008-01-01

    Antarctic fishes are represented by sharks, skates (Chondrichthyes) and bony fishes (Teleostei). Teleosts play an important role in the completion of life cycles of many helminth species. They serve as either definitive or intermediate and paratenic hosts. Chondrichthyes are definitive hosts only. Seventy three helminth species occur as the adult stage in fishes: Digenea (45), Cestoda (14), Nematoda (6), Acanthocephala (8), Also, 11 larval stages of Cestoda (7) and Nematoda (4) are known, together with 7 species of Acanthocephala in the cystacanth stage. One digenean species, Otodistomum cestoides, matures in skates. Among cestodes maturing in fishes only one, Parabothriocephalus johnstoni, occurs in a bony fish, Macrourus whitsoni. Antarctic Chondrichthyes are not infected with nematodes and acanthocephalans. Cestode larvae from teleosts belong to Tetraphyllidea (parasites of skates), and Tetrabothriidae and Diphyllobothriidae (parasites of birds and mammals). Larval nematodes represent Anisakidae, parasites of fishes, birds and mammals. Acanthocephalan cystacanths mature in pinnipeds and birds. The majority of parasites maturing in Antarctic fishes are endemics. Only 4 digenean and one nematode species, Hysterothylacium aduncum, are cosmopolitan. All acanthocephalans, almost all digeneans, the majority of cestodes and some nematodes occur mainly or exclusively in benthic fishes. Specificity of the majority of helminths utilizing teleosts as intermediate and/or paratenic hosts is low. Among parasites using fishes as definitive hosts, all Cestoda, most Digenea and Nematoda, and almost all Acanthocephala have a range of hosts restricted to one order or even to 1-2 host species.

  20. Polaromonas vacuolata gen. nov., sp. nov., a psychrophilic, marine, gas vacuolate bacterium from Antarctica.

    PubMed

    Irgens, R L; Gosink, J J; Staley, J T

    1996-07-01

    Several strains of a novel heterotrophic gas vacuolate bacterium were isolated from antarctic marine waters. The results of phylogenetic analyses in which 16S ribosomal DAN sequencing was used, coupled with phenotypic tests, indicated that strain 34-P(T) (T = type strain) belongs to a new genus and species of the beta subgroup of the Proteobacteria, for which the name Polaromonas vacuolata is proposed. Although the other four strains studied probably belong to this new species, DNA-DNA hybridization tests were not conducted. The closest phylogenetic relatives of P. vacuolata are the photosynthetic nonsulfur purple bacterium Rhodoferax fermentans and the hydrogen autotroph Variovorax paradoxus.

  1. Liquid Chromatography-Mass Spectrometry-Based Rapid Secondary-Metabolite Profiling of Marine Pseudoalteromonas sp. M2

    PubMed Central

    Kim, Woo Jung; Kim, Young Ok; Kim, Jin Hee; Nam, Bo-Hye; Kim, Dong-Gyun; An, Cheul Min; Lee, Jun Sik; Kim, Pan Soo; Lee, Hye Min; Oh, Joa-Sup; Lee, Jong Suk

    2016-01-01

    The ocean is a rich resource of flora, fauna, and food. A wild-type bacterial strain showing confluent growth on marine agar with antibacterial activity was isolated from marine water, identified using 16S rDNA sequence analysis as Pseudoalteromonas sp., and designated as strain M2. This strain was found to produce various secondary metabolites including quinolone alkaloids. Using high-resolution mass spectrometry (MS) and nuclear magnetic resonance (NMR) analysis, we identified nine secondary metabolites of 4-hydroxy-2-alkylquinoline (pseudane-III, IV, V, VI, VII, VIII, IX, X, and XI). Additionally, this strain produced two novel, closely related compounds, 2-isopentylqunoline-4-one and 2-(2,3-dimetylbutyl)qunoline-4-(1H)-one, which have not been previously reported from marine bacteria. From the metabolites produced by Pseudoalteromonas sp. M2, 2-(2,3-dimethylbutyl)quinolin-4-one, pseudane-VI, and pseudane-VII inhibited melanin synthesis in Melan-A cells by 23.0%, 28.2%, and 42.7%, respectively, wherein pseudane-VII showed the highest inhibition at 8 µg/mL. The results of this study suggest that liquid chromatography (LC)-MS/MS-based metabolite screening effectively improves the efficiency of novel metabolite discovery. Additionally, these compounds are promising candidates for further bioactivity development. PMID:26805856

  2. Liquid Chromatography-Mass Spectrometry-Based Rapid Secondary-Metabolite Profiling of Marine Pseudoalteromonas sp. M2.

    PubMed

    Kim, Woo Jung; Kim, Young Ok; Kim, Jin Hee; Nam, Bo-Hye; Kim, Dong-Gyun; An, Cheul Min; Lee, Jun Sik; Kim, Pan Soo; Lee, Hye Min; Oh, Joa-Sup; Lee, Jong Suk

    2016-01-20

    The ocean is a rich resource of flora, fauna, and food. A wild-type bacterial strain showing confluent growth on marine agar with antibacterial activity was isolated from marine water, identified using 16S rDNA sequence analysis as Pseudoalteromonas sp., and designated as strain M2. This strain was found to produce various secondary metabolites including quinolone alkaloids. Using high-resolution mass spectrometry (MS) and nuclear magnetic resonance (NMR) analysis, we identified nine secondary metabolites of 4-hydroxy-2-alkylquinoline (pseudane-III, IV, V, VI, VII, VIII, IX, X, and XI). Additionally, this strain produced two novel, closely related compounds, 2-isopentylqunoline-4-one and 2-(2,3-dimetylbutyl)qunoline-4-(1H)-one, which have not been previously reported from marine bacteria. From the metabolites produced by Pseudoalteromonas sp. M2, 2-(2,3-dimethylbutyl)quinolin-4-one, pseudane-VI, and pseudane-VII inhibited melanin synthesis in Melan-A cells by 23.0%, 28.2%, and 42.7%, respectively, wherein pseudane-VII showed the highest inhibition at 8 µg/mL. The results of this study suggest that liquid chromatography (LC)-MS/MS-based metabolite screening effectively improves the efficiency of novel metabolite discovery. Additionally, these compounds are promising candidates for further bioactivity development.

  3. International Workshop on Antarctic Meteorites

    NASA Technical Reports Server (NTRS)

    Annexstad, J. O.; Schultz, L.; Waenke, H.

    1986-01-01

    Topics addressed include: meteorite concentration mechanisms; meteorites and the Antarctic ice sheet; iron meteorites; iodine overabundance in meteorites; entrainment, transport, and concentration of meteorites in polar ice sheets; weathering of stony meteorites; cosmic ray records; radiocarbon dating; element distribution and noble gas isotopic abundances in lunar meteorites; thermoanalytical characterization; trace elements; thermoluminescence; parent sources; and meteorite ablation and fusion spherules in Antarctic ice.

  4. Antarctic Mapping Tools for MATLAB

    NASA Astrophysics Data System (ADS)

    Greene, Chad A.; Gwyther, David E.; Blankenship, Donald D.

    2017-07-01

    We present the Antarctic Mapping Tools package, an open-source MATLAB toolbox for analysis and plotting of Antarctic geospatial datasets. This toolbox is designed to streamline scientific workflow and maximize repeatability through functions which allow fully scripted data analysis and mapping. Data access is facilitated by several dataset-specific plugins which are freely available online. An open architecture has been chosen to encourage users to develop and share plugins for future Antarctic geospatial datasets. This toolbox includes functions for coordinate transformations, flight line or ship track analysis, and data mapping in georeferenced or projected coordinates. Each function is thoroughly documented with clear descriptions of function syntax alongside examples of data analysis or display using Antarctic geospatial data. The Antarctic Mapping Tools package is designed for ease of use and allows users to perform each step of data processing including raw data import, data analysis, and creation of publication-quality maps, wholly within the numerical environment of MATLAB.

  5. Pseudoalteromonas spp. serve as initial bacterial attractants in mesocosms of coastal waters but have subsequent antifouling capacity in mesocosms and when embedded in paint.

    PubMed

    Bernbom, Nete; Ng, Yoke Yin; Olsen, Stefan Møller; Gram, Lone

    2013-11-01

    The purpose of the present study was to determine if the monoculture antifouling effect of several pigmented pseudoalteromonads was retained in in vitro mesocosm systems using natural coastal seawater and when the bacteria were embedded in paint used on surfaces submerged in coastal waters. Pseudoalteromonas piscicida survived on a steel surface and retained antifouling activity for at least 53 days in sterile seawater, whereas P. tunicata survived and had antifouling activity for only 1 week. However, during the first week, all Pseudoalteromonas strains facilitated rather than prevented bacterial attachment when used to coat stainless steel surfaces and submerged in mesocosms with natural seawater. The bacterial density on surfaces coated with sterile growth medium was 10(5) cells/cm(2) after 7 days, whereas counts on surfaces precoated with Pseudoalteromonas were significantly higher, at 10(6) to 10(8) cells/cm(2). However, after 53 days, seven of eight Pseudoalteromonas strains had reduced total bacterial adhesion compared to the control. P. piscicida, P. antarctica, and P. ulvae remained on the surface, at levels similar to those in the initial coating, whereas P. tunicata could not be detected. Larger fouling organisms were observed on all plates precoated with Pseudoalteromonas; however, plates coated only with sterile growth medium were dominated by a bacterial biofilm. Suspensions of a P. piscicida strain and a P. tunicata strain were incorporated into ship paints (Hempasil x3 87500 and Hempasil 77500) used on plates that were placed at the Hempel A/S test site in Jyllinge Harbor. For the first 4 months, no differences were observed between control plates and treated plates, but after 5 to 6 months, the control plates were more fouled than the plates with pseudoalteromonad-based paint. Our study demonstrates that no single laboratory assay can predict antifouling effects and that a combination of laboratory and real-life methods must be used to determine

  6. Pseudoalteromonas spp. Serve as Initial Bacterial Attractants in Mesocosms of Coastal Waters but Have Subsequent Antifouling Capacity in Mesocosms and when Embedded in Paint

    PubMed Central

    Bernbom, Nete; Ng, Yoke Yin; Olsen, Stefan Møller

    2013-01-01

    The purpose of the present study was to determine if the monoculture antifouling effect of several pigmented pseudoalteromonads was retained in in vitro mesocosm systems using natural coastal seawater and when the bacteria were embedded in paint used on surfaces submerged in coastal waters. Pseudoalteromonas piscicida survived on a steel surface and retained antifouling activity for at least 53 days in sterile seawater, whereas P. tunicata survived and had antifouling activity for only 1 week. However, during the first week, all Pseudoalteromonas strains facilitated rather than prevented bacterial attachment when used to coat stainless steel surfaces and submerged in mesocosms with natural seawater. The bacterial density on surfaces coated with sterile growth medium was 105 cells/cm2 after 7 days, whereas counts on surfaces precoated with Pseudoalteromonas were significantly higher, at 106 to 108 cells/cm2. However, after 53 days, seven of eight Pseudoalteromonas strains had reduced total bacterial adhesion compared to the control. P. piscicida, P. antarctica, and P. ulvae remained on the surface, at levels similar to those in the initial coating, whereas P. tunicata could not be detected. Larger fouling organisms were observed on all plates precoated with Pseudoalteromonas; however, plates coated only with sterile growth medium were dominated by a bacterial biofilm. Suspensions of a P. piscicida strain and a P. tunicata strain were incorporated into ship paints (Hempasil x3 87500 and Hempasil 77500) used on plates that were placed at the Hempel A/S test site in Jyllinge Harbor. For the first 4 months, no differences were observed between control plates and treated plates, but after 5 to 6 months, the control plates were more fouled than the plates with pseudoalteromonad-based paint. Our study demonstrates that no single laboratory assay can predict antifouling effects and that a combination of laboratory and real-life methods must be used to determine the

  7. Improving Antarctic infrastructure

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-07-01

    Noting that U.S. activities in Antarctica “are very well managed but suffer from an aging infrastructure, lack of a capital budget, and the effects of operating in an extremely unforgiving environment,” a 23 July report from the U.S. Antarctic Program Blue Ribbon Panel recommends a number of measures to improve the infrastructure, logistics, and other concerns. The panel's recommendations include continued use of the McMurdo, South Pole, and Palmer stations as the primary U.S. science and logistics hubs in Antarctica—because there are no reasonable alternatives, according to the panel—while upgrading or replacing some facilities, restoring the U.S. polar ocean feet, implementing state of-the-art logistics and transportation support, and establishing a long-term facilities capital plan and budget for the U.S. Antarctic Program. “The essence of our findings is that the lack of capital budgeting has placed operations at McMurdo, and to a somewhat lesser extent at Palmer Station, in unnecessary jeopardy—at least in terms of prolonged inefficiency due to deteriorating or otherwise inadequate physical assets,” the panel wrote in the cover letter accompanying the report entitled, More and Better Science in Antarctica Through Increased Logistical Effectiveness. “The Antarctica Blue Ribbon Panel encourages us to take a hard look at how we support Antarctic science and to make the structural changes, however difficult in the current fiscal environment, that will allow us to do more science in the future,” said U.S. National Science Foundation (NSF) Director Subra Suresh.

  8. Notes on Antarctic Aviation

    DTIC Science & Technology

    1993-08-01

    being made around the coast of East operated a DH Fox Moth on floats in the Antarctic Antarctica by Mawson’s expedition (DH Gypsy Peninsula. In late...Wright Condors (modified AT-32s desig- Little America station and were located by an RAAF nated R4C-1 by the U.S. Navy) and a Staggerwing DH Gypsy Moth ...British use DH Fox Moth in Peninsula. 1930 Byrd uses Ford 4T, Fokker Universal and Fairchild, all on skis. Ford 4T flies to South Pole. Coastal flights

  9. Biodiversity and biogeography of Antarctic and sub-Antarctic mollusca

    NASA Astrophysics Data System (ADS)

    Linse, Katrin; Griffiths, Huw J.; Barnes, David K. A.; Clarke, Andrew

    2006-04-01

    For many decades molluscan data have been critical to the establishment of the concept of a global-scale increase in species richness from the poles to the equator. Low polar diversity is key to this latitudinal cline in diversity. Here we investigate richness patterns in the two largest classes of molluscs at both local and regional scales throughout the Southern Ocean. We show that biodiversity is very patchy in the Southern Ocean (at the 1000-km scale) and test the validity of historical biogeographic sub-regions and provinces. We used multivariate analysis of biodiversity patterns at species, genus and family levels to define richness hotspots within the Southern Ocean and transition areas. This process identified the following distinct sub-regions in the Southern Ocean: Antarctic Peninsula, Weddell Sea, East Antarctic—Dronning Maud Land, East Antarctic—Enderby Land, East Antarctic—Wilkes Land, Ross Sea, and the independent Scotia arc and sub Antarctic islands. Patterns of endemism were very different between the bivalves and gastropods. On the basis of distributional ranges and radiation centres of evolutionarily successful families and genera we define three biogeographic provinces in the Southern Ocean: (1) the continental high Antarctic province excluding the Antarctic Peninsula, (2) the Scotia Sea province including the Antarctic Peninsula, and (3) the sub Antarctic province comprising the islands in the vicinity of the Antarctic Circumpolar Current.

  10. Stardust in Antarctic Micrometeorites

    SciTech Connect

    Yada, Toru; Floss, Christine; Stadermann, Frank J.; Zinner, E.; Nakamura, T.; Noguchi, T.; Lea, Alan S.

    2008-03-07

    We report the discovery of presolar silicate, oxide (hibonite) and (possibly) SiC grains from four Antarctic micrometeorites. The oxygen isotopic compositions of the eighteen presolar silicate (and one oxide) grains found are consistent with those observed previously in primitive meteorites and interplanetary dust particles, and indicate origins in oxygen-rich red giant or asymptotic giant branch stars. Four grains with anomalous C isotopic compositions were also detected. 12C/13C as well as Si ratios are similar to those of mainstream SiC grains; the N isotopic composition of one grain is also consistent with a mainstream SiC classification. Presolar silicate grains were found in three of the seven AMMs studied, and are heterogeneously distributed within these micrometeorites. Fourteen of the 18 presolar silicate grains and 3 of the 4 C-anomalous grains were found within one AMM, T98G8. The presence of magnesiowüstite, which forms mainly through the decomposition of carbonates, in AMMs without presolar silicates, and its absence in the presolar silicate-bearing micrometeorites, suggests that parent body processes (specifically aqueous alteration) may determine the presence or absence of presolar silicates in Antarctic micrometeorites.

  11. Metazoan Parasites of Antarctic Fishes.

    PubMed

    Oğuz, Mehmet Cemal; Tepe, Yahya; Belk, Mark C; Heckmann, Richard A; Aslan, Burçak; Gürgen, Meryem; Bray, Rodney A; Akgül, Ülker

    2015-06-01

    To date, there have been nearly 100 papers published on metazoan parasites of Antarctic fishes, but there has not yet been any compilation of a species list of fish parasites for this large geographic area. Herein, we provide a list of all documented occurrences of monogenean, cestode, digenean, acanthocephalan, nematode, and hirudinean parasites of Antarctic fishes. The list includes nearly 250 parasite species found in 142 species of host fishes. It is likely that there are more species of fish parasites, which are yet to be documented from Antarctic waters.

  12. RADARSAT: The Antarctic Mapping Project

    NASA Technical Reports Server (NTRS)

    Jezek, Kenneth C.; Lindstrom, E. (Technical Monitor)

    2002-01-01

    The first Antarctic Imaging Campaign (AIC) occurred during the period September 9, 1997 through October 20, 1997. The AIC utilized the unique attributes of the Canadian RADARSAT-1 to acquire the first, high-resolution, synthetic aperture imagery covering the entire Antarctic Continent. Although the primary goal of the mission was the acquisition of image data, the nearly flawless execution of the mission enabled additional collections of exact repeat orbit data. These data, covering an extensive portion of the interior Antarctic, potentially are suitable for interferometric analysis of topography and surface velocity. This document summarizes the Project through completion with delivery of products to the NASA DAACs.

  13. Antarctic and non-Antarctic meteorites form different populations

    NASA Technical Reports Server (NTRS)

    Dennison, J. E.; Lingner, D. W.; Lipschutz, M. E.

    1986-01-01

    The trace element differences between Victoria Land H5 chondrites and non-Antarctic H5 chondrites are studied. The focus on common meteorites was stimulated by Antarctic and non-Antarctic differences in meteorite types and in the trace element contents of congeners of rare type. Thirteen elements were analyzed by neutron activation analysis with radiochemical separation, and eight differed significantly. Eliminating test biasing and the possibility of compositional difference due to Antarctic weathering of the 300,000 year-old (on the average) Victoria Land falls, it is concluded that the two sets of chondrites differ due to extraterrestrial causes. The three possibilities discussed, differences in sample population, physical properties, orbital characteristics, and meteoroid flux with time, are all seen as problematic.

  14. Antarctic Meteorite Location Map Series

    NASA Technical Reports Server (NTRS)

    Schutt, John (Editor); Fessler, Brian (Editor); Cassidy, William (Editor)

    1989-01-01

    Antarctica has been a prolific source of meteorites since meteorite concentrations were discovered in 1969. The Antarctic Search For Meteorites (ANSMET) project has been active over much of the Trans-Antarctic Mountain Range. The first ANSMET expedition (a joint U.S.-Japanese effort) discovered what turned out to be a significant concentration of meteorites at the Allan Hills in Victoria Land. Later reconnaissance in this region resulted in the discovery of meteorite concentrations on icefields to the west of the Allan Hills, at Reckling Moraine, and Elephant Moraine. Antarctic meteorite location maps (reduced versions) of the Allan Hills main, near western, middle western, and far western icefields and the Elephant Moraine icefield are presented. Other Antarctic meteorite location maps for the specimens found by the ANSMET project are being prepared.

  15. Antarctic stratospheric ice crystals

    NASA Technical Reports Server (NTRS)

    Goodman, J.; Toon, O. B.; Pueschel, R. F.; Snetsinger, K. G.; Verma, S.

    1989-01-01

    Ice crystals were replicated over the Palmer Peninsula at approximately 72 deg S on six occasions during the 1987 Airboirne Antarctic Ozone Experiment. The sampling altitude was between 12.5 and 18.5 km (45-65 thousand ft pressure altitude) with the temperature between 190 and 201 K. The atmosphere was subsaturated with respect to ice in all cases. The collected crystals were predominantly solid and hollow columns. The largest crystals were sampled at lower altitudes where the potential temperature was below 400 K. While the crystals were larger than anticipated, their low concentration results in a total surface area that is less than one tenth of the total aerosol surface area. The large ice crystals may play an important role in the observed stratospheric dehydration processes through sedimentation. Evidence of scavenging of submicron particles further suggests that the ice crystals may be effective in the removal of stratospheric chemicals.

  16. Seeking the True Antarctic Ocean

    NASA Astrophysics Data System (ADS)

    Miller, R. G.

    2007-12-01

    With World Ocean warming a corrected name use is recommend with a universal adoption of the name, "Antarctic Ocean. This one large body of circumpolar water lies adjacent to - and south of - the Antarctic Convergence, on its northern perimeter, and is bordered to the south by the shoreline of the Antarctic continent. The Antarctic Ocean has a distinct water mass, with a true perimeter, and with a homogeneity, comprizing a unique environment for a specialized flora and fauna. It is recognized generally by its surface waters, ranging from 3.5 - 4.5 degrees Celsius (summer) and one degree C (winter).While its northern boundary, ' The Antarctic Convergence', has a water quality and thermal difference, this polar front is continuous and circumpolar, and it abuts -- and streams along with -- the ultimate southern extremities of the Atlantic, Pacific and Indian Ocean waters. Parameters, characteristics and dynamics of water exchange are considered, here, with some water exchanges, with Intermediate and Antarctic Bottom water noted. It maintains its own forceful 'West Wind Drift', a current driven and emboldened by Earth's Geostrophic West Wind. Features defining the Antarctic Ocean: (1)Washing all shores of the continent named Antarctica; it is .the only ocean reaching this Antarctic Continent.; (2) it is one of Earth's two Polar (and coldest) oceans, the other, named Arctic Ocean, of which it is the opposite (the Anti); (3) its distinctive cold waters of the Antarctic Ocean and its peripheral seas, floating ice tongues, the frigid stamp of Antarctica's continental glaciers and ice fields; (4) the Antarctic Continent is the source of continual replenishment from her ice cap and melt-water derived from the great mountains, valleys and the massive polar dome of ice. Further, in the literature the present usage, 'Southern Ocean', by some authors, confuses the true Antarctic environmental waters (i.e. south of - and within the South Polar Front - Convergence) with southern

  17. Antarctic subglacial lake discharges

    NASA Astrophysics Data System (ADS)

    Pattyn, Frank

    Antarctic subglacial lakes were long time supposed to be relatively closed and stable environments with long residence times and slow circulations. This view has recently been challenged with evidence of active subglacial lake discharge underneath the Antarctic ice sheet. Satellite altimetry observations witnessed rapid changes in surface elevation across subglacial lakes over periods ranging from several months to more than a year, which were interpreted as subglacial lake discharge and subsequent lake filling, and which seem to be a common and widespread feature. Such discharges are comparable to jökulhlaups and can be modeled that way using the Nye-Röthlisberger theory. Considering the ice at the base of the ice sheet at pressure melting point, subglacial conduits are sustainable over periods of more than a year and over distances of several hundreds of kilometers. Coupling of an ice sheet model to a subglacial lake system demonstrated that small changes in surface slope are sufficient to start and sustain episodic subglacial drainage events on decadal time scales. Therefore, lake discharge may well be a common feature of the subglacial hydrological system, influencing the behavior of large ice sheets, especially when subglacial lakes are perched at or near the onset of large outlet glaciers and ice streams. While most of the observed discharge events are relatively small (101-102 m3 s-1), evidence for larger subglacial discharges is found in ice free areas bordering Antarctica, and witnessing subglacial floods of more than 106 m3 s-1 that occurred during the middle Miocene.

  18. Antarctic Crabs: Invasion or Endurance?

    PubMed Central

    Griffiths, Huw J.; Whittle, Rowan J.; Roberts, Stephen J.; Belchier, Mark; Linse, Katrin

    2013-01-01

    Recent scientific interest following the “discovery” of lithodid crabs around Antarctica has centred on a hypothesis that these crabs might be poised to invade the Antarctic shelf if the recent warming trend continues, potentially decimating its native fauna. This “invasion hypothesis” suggests that decapod crabs were driven out of Antarctica 40–15 million years ago and are only now returning as “warm” enough habitats become available. The hypothesis is based on a geographically and spatially poor fossil record of a different group of crabs (Brachyura), and examination of relatively few Recent lithodid samples from the Antarctic slope. In this paper, we examine the existing lithodid fossil record and present the distribution and biogeographic patterns derived from over 16,000 records of Recent Southern Hemisphere crabs and lobsters. Globally, the lithodid fossil record consists of only two known specimens, neither of which comes from the Antarctic. Recent records show that 22 species of crabs and lobsters have been reported from the Southern Ocean, with 12 species found south of 60°S. All are restricted to waters warmer than 0°C, with their Antarctic distribution limited to the areas of seafloor dominated by Circumpolar Deep Water (CDW). Currently, CDW extends further and shallower onto the West Antarctic shelf than the known distribution ranges of most lithodid species examined. Geological evidence suggests that West Antarctic shelf could have been available for colonisation during the last 9,000 years. Distribution patterns, species richness, and levels of endemism all suggest that, rather than becoming extinct and recently re-invading from outside Antarctica, the lithodid crabs have likely persisted, and even radiated, on or near to Antarctic slope. We conclude there is no evidence for a modern-day “crab invasion”. We recommend a repeated targeted lithodid sampling program along the West Antarctic shelf to fully test the validity of the

  19. Antarctic crabs: invasion or endurance?

    PubMed

    Griffiths, Huw J; Whittle, Rowan J; Roberts, Stephen J; Belchier, Mark; Linse, Katrin

    2013-01-01

    Recent scientific interest following the "discovery" of lithodid crabs around Antarctica has centred on a hypothesis that these crabs might be poised to invade the Antarctic shelf if the recent warming trend continues, potentially decimating its native fauna. This "invasion hypothesis" suggests that decapod crabs were driven out of Antarctica 40-15 million years ago and are only now returning as "warm" enough habitats become available. The hypothesis is based on a geographically and spatially poor fossil record of a different group of crabs (Brachyura), and examination of relatively few Recent lithodid samples from the Antarctic slope. In this paper, we examine the existing lithodid fossil record and present the distribution and biogeographic patterns derived from over 16,000 records of Recent Southern Hemisphere crabs and lobsters. Globally, the lithodid fossil record consists of only two known specimens, neither of which comes from the Antarctic. Recent records show that 22 species of crabs and lobsters have been reported from the Southern Ocean, with 12 species found south of 60 °S. All are restricted to waters warmer than 0 °C, with their Antarctic distribution limited to the areas of seafloor dominated by Circumpolar Deep Water (CDW). Currently, CDW extends further and shallower onto the West Antarctic shelf than the known distribution ranges of most lithodid species examined. Geological evidence suggests that West Antarctic shelf could have been available for colonisation during the last 9,000 years. Distribution patterns, species richness, and levels of endemism all suggest that, rather than becoming extinct and recently re-invading from outside Antarctica, the lithodid crabs have likely persisted, and even radiated, on or near to Antarctic slope. We conclude there is no evidence for a modern-day "crab invasion". We recommend a repeated targeted lithodid sampling program along the West Antarctic shelf to fully test the validity of the "invasion hypothesis".

  20. The Antarctic Master Directory -- a resource for Antarctic Scientists

    NASA Astrophysics Data System (ADS)

    Scharfen, G.; Bauer, R.

    2002-12-01

    Under the auspices of the Antarctic Treaty, a group of nations conducting Antarctic scientific research have created the Antarctic Master Directory (AMD), a resource for Antarctic scientists. The AMD is a Web-based, searchable directory containing data descriptions (metadata in the form of DIF entries) of Antarctic scientific data, and is a node of the International Directory Network/Global Change Master Directory (IDN/GCMD). The data descriptions in the AMD, essentially a data catalog of Antarctic scientific data, include information about what data were collected, where they were collected, when they were collected, who the scientists are, who the point of contact is, and information about the format of the data and what documentation and bibliographic information exists. As part of the AMD effort, the National Science Foundation Office of Polar Programs (OPP) funds the National Snow and Ice Data Center to operate the U.S. Antarctic Data Coordination Center (USADCC), the US focal point for the AMD. The USADCC assists PIs as they meet the requirements of the OPP "Guidelines and Award Conditions for Scientific Data", which identify the conditions for awards and responsibilities of PIs regarding the archival of data, and submission of metadata, resulting from their NSF OPP grants. The USADCC offers access to free, easy-to-use online tools that PIs can use to create the data descriptions that the NSF policy data requires. We provide advice to PIs on how to meet the data policy requirements, and can answer specific questions on related issues. Scientists can access data set descriptions submitted to the AMD, by thousands of scientists around the world, from the USADCC web pages.

  1. Draft Genome Sequences of Pseudoalteromonas telluritireducens DSM 16098 and P. spiralis DSM 16099 Isolated from the Hydrothermal Vents of the Juan de Fuca Ridge

    PubMed Central

    Liu, Rui; Wang, Mengqiang; Wang, Hao; Gao, Qiang; Hou, Zhanhui; Zhou, Zhi; Gao, Dahai

    2016-01-01

    This report describes the draft genome sequences of two strains, Pseudoalteromonas telluritireducens DSM 16098 and P. spiralis DSM 16099, which were isolated from hydrothermal vents of the Juan de Fuca Ridge. The reads generated by an Ion Torrent PGM were assembled into contigs with total sizes of 4.4 Mb and 4.1 Mb for DSM 16098 and DSM 16099, respectively. PMID:27563045

  2. Draft Genome Sequences of Pseudoalteromonas telluritireducens DSM 16098 and P. spiralis DSM 16099 Isolated from the Hydrothermal Vents of the Juan de Fuca Ridge.

    PubMed

    Zhang, Huan; Liu, Rui; Wang, Mengqiang; Wang, Hao; Gao, Qiang; Hou, Zhanhui; Zhou, Zhi; Gao, Dahai; Wang, Lingling

    2016-08-25

    This report describes the draft genome sequences of two strains, Pseudoalteromonas telluritireducens DSM 16098 and P. spiralis DSM 16099, which were isolated from hydrothermal vents of the Juan de Fuca Ridge. The reads generated by an Ion Torrent PGM were assembled into contigs with total sizes of 4.4 Mb and 4.1 Mb for DSM 16098 and DSM 16099, respectively. Copyright © 2016 Zhang et al.

  3. Antarctic Miocene Climate

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Lewis, A. R.

    2013-12-01

    Fossils from Antarctic Miocene terrestrial deposits, coupled with stratigraphic, geochemical and paleontological data from marine boreholes, provide new insights into the climatic history of the continent. During the Miocene, ice caps coalesced to form ice sheets and vegetated surfaces gave way to barren expanses. The cryospheric changes especially have global climatic implications. The fossil data consists of diatoms, pollen and spores, and macroscopic remains of plants, ostracods, insects, molluscs and a fish. Plant fossils include wood and leaves of Nothofagus (southern beech), seeds of several vascular plants, including Ranunculus (buttercup), Hippuris (mare's-tail) and Myriophyllum (watermilfoil), megaspores of Isoetes (quillwort), and moss species. The insect chitin consists of larval head capsules of Chironomidae (midges) and exoskeletal parts of Coleoptera (beetles). The molluscs include freshwater gastropods and bivalves. The majority of these taxa are likely descendants of taxa that had survived on the continent from the Paleogene or earlier. Even though early Miocene glaciations may have been large, the climate was never cold enough to cause the extinction of the biota, which probably survived in coastal refugia. Early Miocene (c. 20 Ma) macrofossils from the McMurdo Dry Valleys (77°S) support palynological interpretations from the Cape Roberts and ANDRILL marine records that the upland vegetation was a shrub tundra. Mean summer temperature (MST) in the uplands was c. 6°C and possibly higher at the coast. The climate was wet, supporting mires and lakes. By the mid-Miocene, even though the climate continued to be wet. MST was c. 4°C which was too cold to support Nothofagus and most vascular plant species. Stratigraphic evidence indicates that the time between the Early and Mid-Miocene was a time of repeated ice advances and retreats of small glaciers originating from ice caps. At c. 14 Ma there appears to have been a modal shift in climate to

  4. Environmental contamination in Antarctic ecosystems.

    PubMed

    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

  5. Towers for Antarctic Telescopes

    NASA Astrophysics Data System (ADS)

    Hammerschlag, R. H.; Bettonvil, F. C. M.; Jägers, A. P. L.; Nielsen, G.

    To take advantage of the exceptional seeing above the boundary layer on Antarctic sites, a high-resolution telescope must be mounted on a support tower. An open transparent tower of framework minimizes the upward temperature-disturbed airflow. A typical minimum height is 30m. The tower platform has to be extremely stable against wind-induced rotational motions, which have to be less than fractions of an arc second, unusually small from a mechanical engineering viewpoint. In a traditional structure, structural deflections result in angular deflections of the telescope platform, which introduce tip and tilt motions in the telescope. However, a structure that is designed to deflect with parallel motion relative to the horizontal plane will undergo solely translation deflections in the telescope platform and thus will not degrade the image. The use of a parallel motion structure has been effectively demonstrated in the design of the 15-m tower for the Dutch Open Telescope (DOT) on La Palma. Special framework geometries are developed, which make it possible to construct high towers in stories having platforms with extreme stability against wind-induced tilt. These geometric solutions lead to constructions, being no more massive than a normal steel framework carrying the same load. Consequently, these lightweight towers are well suited to difficult sites as on Antarctica. A geometry with 4 stories has been worked out.

  6. Antarctic radiation exposure doubles

    NASA Astrophysics Data System (ADS)

    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.

  7. Multidecadal warming of Antarctic waters.

    PubMed

    Schmidtko, Sunke; Heywood, Karen J; Thompson, Andrew F; Aoki, Shigeru

    2014-12-05

    Decadal trends in the properties of seawater adjacent to Antarctica are poorly known, and the mechanisms responsible for such changes are uncertain. Antarctic ice sheet mass loss is largely driven by ice shelf basal melt, which is influenced by ocean-ice interactions and has been correlated with Antarctic Continental Shelf Bottom Water (ASBW) temperature. We document the spatial distribution of long-term large-scale trends in temperature, salinity, and core depth over the Antarctic continental shelf and slope. Warming at the seabed in the Bellingshausen and Amundsen seas is linked to increased heat content and to a shoaling of the mid-depth temperature maximum over the continental slope, allowing warmer, saltier water greater access to the shelf in recent years. Regions of ASBW warming are those exhibiting increased ice shelf melt. Copyright © 2014, American Association for the Advancement of Science.

  8. Antarctic Peninsula and Weddell Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Numerous icebergs are breaking out of the sea ice in the Southern Ocean surrounding the Antarctic Peninsula. This true-color MODIS image from November 13, 2001, shows several icebergs drifting out of the Weddell Sea. The Antarctic Peninsula (left) reaches out into the Drake Passage, which separates the southern tip of South America from Antarctica. Warmer temperatures have cleared a tiny patch of bare ground at the Peninsula's tip. The predominant ocean current in the area is the Antarctic Circumpolar Current ('circum' meaning 'around'), which is also the 'West Wind Drift.' The current is the largest permanent current in the world, and water is moved eastward by westerly winds. Icebergs leaving the Weddell Sea are likely to be moved north and east by the current. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  9. Antarctic Ozone Hole, 2000

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Each spring the ozone layer over Antarctica nearly disappears, forming a 'hole' over the entire continent. The hole is created by the interaction of some man-made chemicals-freon, for example-with Antarctica's unique weather patterns and extremely cold temperatures. Ozone in the stratosphere absorbs ultraviolet radiation from the sun, thereby protecting living things. Since the ozone hole was discovered many of the chemicals that destroy ozone have been banned, but they will remain in the atmosphere for decades. In 2000, the ozone hole grew quicker than usual and exceptionally large. By the first week in September the hole was the largest ever-11.4 million square miles. The top image shows the average total column ozone values over Antarctica for September 2000. (Total column ozone is the amount of ozone from the ground to the top of the atmosphere. A relatively typical measurement of 300 Dobson Units is equivalent to a layer of ozone 0.12 inches thick on the Earth's surface. Levels below 220 Dobson Units are considered to be significant ozone depletion.) The record-breaking hole is likely the result of lower than average ozone levels during the Antarctic fall and winter, and exceptionally cold temperatures. In October, however (bottom image), the hole shrank dramatically, much more quickly than usual. By the end of October, the hole was only one-third of it's previous size. In a typical year, the ozone hole does not collapse until the end of November. NASA scientists were surprised by this early shrinking and speculate it is related to the region's weather. Global ozone levels are measured by the Total Ozone Mapping Spectrometer (TOMS). For more information about ozone, read the Earth Observatory's ozone fact sheet, view global ozone data and see these ozone images. Images by Greg Shirah, NASA GSFC Scientific Visualization Studio.

  10. Antarctic analogs for Enceladus

    NASA Astrophysics Data System (ADS)

    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.

  11. Cloning, expression, purification, and characterization of cold-adapted α-amylase from Pseudoalteromonas arctica GS230.

    PubMed

    Lu, Mingsheng; Wang, Shujun; Fang, Yaowei; Li, Huangzhong; Liu, Shu; Liu, Hongfei

    2010-11-01

    A cold-adapted α-amylase (ParAmy) gene from Pseudoalteromonas arctica GS230 was cloned, sequenced, and expressed as an N-terminus His-tag fusion protein in E. coli. A recombinant protein was produced and purified with DEAE-sepherose ion exchange chromatography and Ni affinity chromatography. The molecular weight of ParAmy was estimated to be 55 KDa with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). With an optimum temperature for activity 30 °C, ParAmy showed 34.5% of maximum activity at 0 °C and its activity decreased sharply at above 40 °C. ParAmy was stable in the range of pH 7-8.5 at 30 °C for 1 h. ParAmy was activated by Mn(2+), K(+) and Na(+), and inhibited by Hg(2+), Cu(2+), and Fe(3+). N-Bromosuccinimid showed a significant repressive effect on enzyme activity. The K (m) and V (max) values of the α-amylase for soluble starch were 7.28 mg/mL and 13.07 mg/mL min, respectively. This research suggests that Paramy has a good potential to be a cold-stable and alkalitolerant amylase in detergent industry.

  12. Molecular cloning and characterization of a novel beta-agarase, AgaB, from marine Pseudoalteromonas sp. CY24.

    PubMed

    Ma, Cuiping; Lu, Xinzhi; Shi, Chao; Li, Jingbao; Gu, Yuchao; Ma, Yiming; Chu, Yan; Han, Feng; Gong, Qianhong; Yu, Wengong

    2007-02-09

    Agarases are generally classified into glycoside hydrolase families 16, 50, and 86 and are found to degrade agarose to frequently generate neoagarobiose, neoagarotetraose, or neoagarohexaose as the main products. In this study we have cloned a novel endo-type beta-agarase gene, agaB, from marine Pseudoalteromonas sp. CY24. The novel agarase encoded by agaB gene has no significant sequence similarity with any known proteins including all glycoside hydrolases. It degrades agarose to generate neoagarooctaose and neoagarodecaose as the main end products. Based on the analyses of enzymatic kinetics and degradation patterns of different oligosaccharides, the agarase AgaB appears to have a large substrate binding cleft that accommodates 12 sugar units, with 8 sugar units toward the reducing end spanning subsites +1 to +8 and 4 sugar units toward the non-reducing end spanning subsites -4 to -1, and enzymatic cleavage taking place between subsites -1 and +1. In addition, 1H NMR analysis shows that this enzyme hydrolyzes the glycosidic bond with inversion of anomeric configuration, in contrast to other known agarases that are retaining. Altogether, AgaB is structurally and functionally different from other known agarases and appears to represent a new family of glycoside hydrolase.

  13. Single Bacterium Detection Using Sers

    NASA Astrophysics Data System (ADS)

    Gonchukov, S. A.; Baikova, T. V.; Alushin, M. V.; Svistunova, T. S.; Minaeva, S. A.; Ionin, A. A.; Kudryashov, S. I.; Saraeva, I. N.; Zayarny, D. A.

    2016-02-01

    This work is devoted to the study of a single Staphylococcus aureus bacterium detection using surface-enhanced Raman spectroscopy (SERS) and resonant Raman spectroscopy (RS). It was shown that SERS allows increasing sensitivity of predominantly low frequency lines connected with the vibrations of Amide, Proteins and DNA. At the same time the lines of carotenoids inherent to this kind of bacterium are well-detected due to the resonance Raman scattering mechanism. The reproducibility and stability of Raman spectra strongly depend on the characteristics of nanostructured substrate, and molecular structure and size of the tested biological object.

  14. Sanguibacter antarcticus sp. nov., isolated from Antarctic sea sand.

    PubMed

    Hong, Soon Gyu; Lee, Yoo Kyung; Yim, Joung Han; Chun, Jongsik; Lee, Hong Kum

    2008-01-01

    A Gram-positive, yellow-pigmented bacterium, strain KOPRI 21702(T), was isolated from sea sand on King George Island, Antarctica. Cells were irregular rods with peritrichous flagella; their optimum growth temperature was 23-26 degrees C. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the Antarctic isolate formed a distinct phyletic line in a clade of the genus Sanguibacter and showed highest sequence similarity (97.7%) to the type strain of Sanguibacter keddieii. The major isoprenoid quinone, predominant cellular fatty acids and DNA G+C content were consistent with placement of the Antarctic isolate in the genus Sanguibacter. Phylogenetic analysis and differences in physiological and biochemical characteristics between strain KOPRI 21702(T) and the four recognized Sanguibacter species indicate that the isolate represents a novel species of this genus. The name Sanguibacter antarcticus sp. nov. (type strain KOPRI 21702(T) =KCTC 13143(T) =JCM 14623(T) =DSM 18966(T)) is proposed for this isolate.

  15. Principles of the Antarctic Treaty

    NASA Astrophysics Data System (ADS)

    Candidi, M.

    The operation of any base or expedition to Antarctica is regulated by the mutual agreement among nations in the “Antarctic Treaty”. This treaty deals with the major aspects of life in Antarctica and its main principles and provisions are described in what follows.

  16. Feeding repellence in Antarctic bryozoans

    NASA Astrophysics Data System (ADS)

    Figuerola, Blanca; Núñez-Pons, Laura; Moles, Juan; Avila, Conxita

    2013-11-01

    The Antarctic sea star Odontaster validus and the amphipod Cheirimedon femoratus are important predators in benthic communities. Some bryozoans are part of the diet of the asteroid and represent both potential host biosubstrata and prey for this omnivorous lysianassid amphipod. In response to such ecological pressure, bryozoans are expected to develop strategies to deter potential predators, ranging from physical to chemical mechanisms. However, the chemical ecology of Antarctic bryozoans has been scarcely studied. In this study we evaluated the presence of defenses against predation in selected species of Antarctic bryozoans. The sympatric omnivorous consumers O. validus and C. femoratus were selected to perform feeding assays with 16 ether extracts (EE) and 16 butanol extracts (BE) obtained from 16 samples that belonged to 13 different bryozoan species. Most species (9) were active (12 EE and 1 BE) in sea star bioassays. Only 1 BE displayed repellence, indicating that repellents against the sea star are mainly lipophilic. Repellence toward C. femoratus was found in all species in different extracts (10 EE and 12 BE), suggesting that defenses against the amphipod might be both lipophilic and hydrophilic. Interspecific and intraspecific variability of bioactivity was occasionally detected, suggesting possible environmental inductive responses, symbiotic associations, and/or genetic variability. Multivariate analysis revealed similarities among species in relation to bioactivities of EE and/or BE. These findings support the hypothesis that, while in some cases alternative chemical or physical mechanisms may also provide protection, repellent compounds play an important role in Antarctic bryozoans as defenses against predators.

  17. Extent of the Antarctic Continent.

    PubMed

    Press, F; Dewart, G

    1959-02-20

    Group velocities of eartquake-generated Love and Rayleigh waves for certain transantarctic paths are abnormally high when compared with data from other continents. For these paths, the data indicate that at most only three-fourths of the antarctic ice sheet is underlain by continent, the remaining area being oceanic in structure.

  18. Glaciology: Vulnerable Antarctic ice shelves

    NASA Astrophysics Data System (ADS)

    Siegert, Martin

    2017-01-01

    The decay of floating ice shelves around Antarctica speeds up ice flow from the continent and contributes to increased sea-level rise. Now, meltwater attributed to warm winds has been discovered on an East Antarctic ice shelf, suggesting greater vulnerability than previously thought.

  19. Radarsat Antarctic Mapping Project: Antarctic Imaging Campaign 2

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Radarsat Antarctic Mapping Project is a collaboration between NASA and the Canadian Space Agency to map Antarctica using synthetic aperture radar (SAR). The first Antarctic Mapping Mission (AMM-1) was successfully completed in October 1997. Data from the acquisition phase of the 1997 campaign have been used to achieve the primary goal of producing the first, high-resolution SAR image map of Antarctica. The limited amount of data suitable for interferometric analysis have also been used to produce remarkably detailed maps of surface velocity for a few selected regions. Most importantly, the results from AMM-1 are now available to the general science community in the form of various resolution, radiometrically calibrated and geometrically accurate image mosaics. The second Antarctic imaging campaign occurred during the fall of 2000. Modified from AMM-1, the satellite remained in north looking mode during AMM-2 restricting coverage to regions north of about -80 degrees latitude. But AMM-2 utilized for the first time RADARSAT-1 fine beams providing an unprecedented opportunity to image many of Antarctica's fast glaciers whose extent was revealed through AMM-1 data. AMM-2 also captured extensive data suitable for interferometric analysis of the surface velocity field. This report summarizes the science goals, mission objectives, and project status through the acquisition phase and the start of the processing phase. The reports describes the efforts of team members including Alaska SAR Facility, Jet Propulsion Laboratory, Vexcel Corporation, Goddard Space Flight Center, Wallops Flight Facility, Ohio State University, Environmental Research Institute of Michigan, White Sands Facility, Canadian Space Agency Mission Planning and Operations Groups, and the Antarctic Mapping Planning Group.

  20. Chemical studies of differentiated meteorites. I - Labile trace elements in Antarctic and non-Antarctic eucrites

    NASA Technical Reports Server (NTRS)

    Paul, Rick L.; Lipschutz, Michael E.

    1990-01-01

    Element contents of Ag, Au, Bi, Cd, Co, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U, and Zn were analyzed, using RNAA, in 25 Antarctic and nine non-Antarctic eucrites to determine whether these two populations differ significantly in thermal history and derive from the same or different eucrite parent body. Data for these 15 elements indicate that basaltic Antarctic and non-Antarctic eucrite populations reflect the same genetic processes and, hence, come from the same parent asteroid.

  1. Chemical studies of differentiated meteorites. I - Labile trace elements in Antarctic and non-Antarctic eucrites

    NASA Technical Reports Server (NTRS)

    Paul, Rick L.; Lipschutz, Michael E.

    1990-01-01

    Element contents of Ag, Au, Bi, Cd, Co, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U, and Zn were analyzed, using RNAA, in 25 Antarctic and nine non-Antarctic eucrites to determine whether these two populations differ significantly in thermal history and derive from the same or different eucrite parent body. Data for these 15 elements indicate that basaltic Antarctic and non-Antarctic eucrite populations reflect the same genetic processes and, hence, come from the same parent asteroid.

  2. Multibranch Antarctic Seismic Data Library facilitates research

    NASA Astrophysics Data System (ADS)

    Cooper, Alan K.

    In 1991, investigators from 11 nations involved in Antarctic multichannel seismic (MCS) reflection research sought a way to keep the Antarctic Treaty's promise of open access to data, and in the process to encourage Earth-science research using seismic data. The Antarctic Seismic Data Library System for Cooperative Research (SDLS) was the solution, and is now a recommendation of the Antarctic Treaty Consultative Parties (ATCP). Today—at 12 branches spanning the world—researchers can access over 68,000 km of marine MCS data to use for cooperative research.More than 150,000 km of MCS data have been accumulated since 1976 by 13 countries on nearly 70 cruises. The majority of data now in the library cover the Ross Sea, Wilkes Land, and Prydz Bay sectors of the Antarctic margin, with smaller amounts from the Weddell Sea and the Antarctic Peninsula.

  3. United States Antarctic Resource Center (USARC)

    USGS Publications Warehouse

    ,

    2001-01-01

    The U.S. Antarctic Resource Center (USARC) is our Nation?s depository for Antarctic maps, charts, geodetic ground control, satellite images, aerial photographs, publications, slides, and video tapes. These resources are items produced by Antarctic Treaty nations in support of their activities in Antarctica and provided to the USARC in compliance with a standing resolution of the treaty providing for exchange of information. The U.S. Geological Survey (USGS) maintains these materials through an interagency cooperative agreement with the National Science Foundation (NSF), which also supports the USGS Antarctic Mapping Program. The USARC develops and maintains the Antarctic Web site (usarc.usgs.gov) and its supporting data bases, as well as providing access to other online digital data bases, such as the Atlas of Antarctic Resources.

  4. Breakup of Pack Ice, Antarctic Ice Shelf

    NASA Image and Video Library

    1991-09-18

    STS048-152-007 (12-18 Sept 1991) --- The periphery of the Antarctic ice shelf and the Antarctic Peninsula were photographed by the STS 48 crew members. Strong offshore winds, probably associated with katabatic winds from the interior of the continent, are peeling off the edges of the ice shelf into ribbons of sea ice, icebergs, bergy bits and growlers into the cold waters of the circum-Antarctic southern ocean.

  5. Introduction to the Antarctic plateau

    NASA Astrophysics Data System (ADS)

    Storey, J. W. V.

    2006-10-01

    Over the past decade there has been remarkable progress in the exploration of the Antarctic plateau for astronomy. Already, major astronomical facilities are in operation at the Amundsen-Scott Station at South Pole, and even more ambitious telescopes are planned or under construction there. However, for a number of important reasons the high plateau sites of Dome A and Dome C appear to offer even more favorable conditions than South Pole for many kinds of astronomy. The success of the Chinese expedition to Dome A in January 2005, plus the opening of the French/Italian Concordia Station at Dome C for year-round operation in 2005, have now created exciting new opportunities for Antarctic astronomy.

  6. Introduction to the Antarctic Plateau

    NASA Astrophysics Data System (ADS)

    Storey, J. W. V.

    2007-01-01

    Over the past decade there has been remarkable progress in the exploration of the Antarctic plateau for astronomy. Already, major astronomical facilities are in operation at the Amundsen-Scott Station at South Pole, and even more ambitious telescopes are planned or under construction there. However, for a number of important reasons the high plateau sites of Dome A and Dome C appear to offer even more favourable conditions than South Pole for many kinds of astronomy. The success of the Chinese expedition to Dome A in January 2005, plus the opening of the French/Italian Concordia Station at Dome C for year-round operation in 2005, have now created exciting new opportunities for Antarctic astronomy.

  7. Ice Bridge Antarctic Sea Ice

    NASA Image and Video Library

    2009-10-21

    An iceberg is seen out the window of NASA's DC-8 research aircraft as it flies 2,000 feet above the Amundsen Sea in West Antarctica on Wednesday, Oct., 21, 2009. This was the fourth science flight of NASA’s Operation Ice Bridge airborne Earth science mission to study Antarctic ice sheets, sea ice, and ice shelves. Photo Credit: (NASA/Jane Peterson)

  8. Ice Bridge Antarctic Sea Ice

    NASA Image and Video Library

    2009-10-21

    Sea ice is seen out the window of NASA's DC-8 research aircraft as it flies 2,000 feet above the Bellingshausen Sea in West Antarctica on Wednesday, Oct., 21, 2009. This was the fourth science flight of NASA’s Operation Ice Bridge airborne Earth science mission to study Antarctic ice sheets, sea ice, and ice shelves. Photo Credit: (NASA/Jane Peterson)

  9. Geographic names of the Antarctic

    USGS Publications Warehouse

    ,; ,; ,; ,; Alberts, Fred G.

    1995-01-01

    This gazetteer contains 12,710 names approved by the United States Board on Geographic Names and the Secretary of the Interior for features in Antarctica and the area extending northward to the Antarctic Convergence. Included in this geographic area, the Antarctic region, are the off-lying South Shetland Islands, the South Orkney Islands, the South Sandwich Islands, South Georgia, Bouvetøya, Heard Island, and the Balleny Islands. These names have been approved for use by U.S. Government agencies. Their use by the Antarctic specialist and the public is highly recommended for the sake of accuracy and uniformity. This publication, which supersedes previous Board gazetteers or lists for the area, contains names approved as recently as December 1994. The basic name coverage of this gazetteer corresponds to that of maps at the scale of 1:250,000 or larger for coastal Antarctica, the off-lying islands, and isolated mountains and ranges of the continent. Much of the interior of Antarctica is a featureless ice plateau. That area has been mapped at a smaller scale and is nearly devoid of toponyms. All of the names are for natural features, such as mountains, glaciers, peninsulas, capes, bays, islands, and subglacial entities. The names of scientific stations have not been listed alphabetically, but they may appear in the texts of some decisions. For the names of submarine features, reference should be made to the Gazetteer of Undersea Features, 4th edition, U.S. Board on Geographic Names, 1990.

  10. Snow on Antarctic sea ice

    NASA Astrophysics Data System (ADS)

    Massom, Robert A.; Eicken, Hajo; Hass, Christian; Jeffries, Martin O.; Drinkwater, Mark R.; Sturm, Matthew; Worby, Anthony P.; Wu, Xingren; Lytle, Victoria I.; Ushio, Shuki; Morris, Kim; Reid, Phillip A.; Warren, Stephen G.; Allison, Ian

    2001-08-01

    Snow on Antarctic sea ice plays a complex and highly variable role in air-sea-ice interaction processes and the Earth's climate system. Using data collected mostly during the past 10 years, this paper reviews the following topics: snow thickness and snow type and their geographical and seasonal variations; snow grain size, density, and salinity; frequency of occurrence of slush; thermal conductivity, snow surface temperature, and temperature gradients within snow; and the effect of snow thickness on albedo. Major findings include large regional and seasonal differences in snow properties and thicknesses; the consequences of thicker snow and thinner ice in the Antarctic relative to the Arctic (e.g., the importance of flooding and snow-ice formation); the potential impact of increasing snowfall resulting from global climate change; lower observed values of snow thermal conductivity than those typically used in models; periodic large-scale melt in winter; and the contrast in summer melt processes between the Arctic and the Antarctic. Both climate modeling and remote sensing would benefit by taking account of the differences between the two polar regions.

  11. Heavy metals in Antarctic organisms

    SciTech Connect

    Moreno, J.E.A. de; Moreno, V.J.; Gerpe, M.S.; Vodopivez, C.

    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.

  12. Biofilm lifestyle enhances diesel bioremediation and biosurfactant production in the Antarctic polyhydroxyalkanoate producer Pseudomonas extremaustralis.

    PubMed

    Tribelli, Paula M; Di Martino, Carla; López, Nancy I; Raiger Iustman, Laura J

    2012-09-01

    Diesel is a widely distributed pollutant. Bioremediation of this kind of compounds requires the use of microorganisms able to survive and adapt to contaminated environments. Pseudomonas extremaustralis is an Antarctic bacterium with a remarkable survival capability associated to polyhydroxyalkanoates (PHAs) production. This strain was used to investigate the effect of cell growth conditions--in biofilm versus shaken flask cultures--as well as the inocula characteristics associated with PHAs accumulation, on diesel degradation. Biofilms showed increased cell growth, biosurfactant production and diesel degradation compared with that obtained in shaken flask cultures. PHA accumulation decreased biofilm cell attachment and enhanced biosurfactant production. Degradation of long-chain and branched alkanes was observed in biofilms, while in shaken flasks only medium-chain length alkanes were degraded. This work shows that the PHA accumulating bacterium P. extremaustralis can be a good candidate to be used as hydrocarbon bioremediation agent, especially in extreme environments.

  13. Characterization and Genome Sequencing of a Novel Bacteriophage PH101 Infecting Pseudoalteromonas marina BH101 from the Yellow Sea of China.

    PubMed

    Wang, Duo-bing; Sun, Meng-qi; Shao, Hong-bing; Li, Yan; Meng, Xue; Liu, Zhao-yang; Wang, Min

    2015-11-01

    A novel Pseudoalteromonas marina bacteriophage, PH101, specifically infecting Pseudoalteromonas BH101 was isolated from the water sample of the Yellow Sea of China using the agar overlay method. 16S rDNA sequence identification was used to identify the host bacteria. Efficiency of infection, multiplicity of infection value, morphological characterization, one-step growth curve, and host range of the bacteriophage were determined. Purified PH101 genomic DNA was extracted and its genome was completely sequenced and analyzed. The phage morphology showed that PH101 belongs to the Myoviridae family with a head of 60 nm in diameter and a tail of 40 nm with a tail fiber of 10-20 nm. Microbiological characterization demonstrated that phage PH101 is stable at a wide range of temperatures (0-70 °C) and showed acid and alkaline resistance (pH 3-12). The one-step growth curve showed a latent period of about 20 min, a rise period of 20 min, and a burst size of about 31.6 virions. The genome sequencing and bioinformatic analysis shows that phage PH101 was a novel bacteriophage which was found to consist of a linear, double-stranded 131,903-bp DNA molecule with a GC content of 37.36 % and 228 putative open reading frames without RNA, which were classified into seven functional groups, including phage structure, adsorption, packaging, gene transfer protease, terminase, DNA binding, and regulation.

  14. JCADM, new directions in Antarctic data management

    NASA Astrophysics Data System (ADS)

    Campbell, H.; de Bruin, T. F.

    2008-12-01

    The Joint Committee on Antarctic Data Management (JCADM) was established by the Scientific Committee on Antarctic Research (SCAR) and the Council of Managers of National Antarctic Programs (COMNAP), to assist in the fulfilment of the data management obligations imposed by the Antarctic Treaty (section III.1.c): "Scientific observations and results from Antarctica shall be exchanged and made freely available." JCADM comprises representatives of the National Antarctic Data Centres or national points of contact. Currently 31 nations around the world are represented in JCADM. So far, JCADM has been focussing on the coordination of the Antarctic Master Directory (AMD), the internationally accessible, web-based, searchable record of Antarctic and Southern Ocean data set descriptions. The AMD is directly integrated into the international Global Change Master Directory (GCMD) to help further merge Antarctic science into global science. The AMD is a resource for scientists to advertise the data they have collected and to search for data they may need. Currently, JCADM is in a transition phase, moving forward to provide data access. Existing systems and web services technology will be used as much as possible, to increase efficiency and prevent 're-inventing the wheel' This poster will give an overview of this process, the current status and the expected results.

  15. Antarctic Meteorite Newsletter, Volume 28, Number 2

    NASA Technical Reports Server (NTRS)

    Righter, Kevin (Editor); Satterwhite, Cecilia (Editor)

    2005-01-01

    This newsletter contains classifications for 274 new meteorites from the 2003 and 2004 ANtarctic Search for METeorites (ANSMET) collections. They include samples from the Cumulus Hills, Larkman Nunatak, LaPaz Ice Field, MacAlpine Hills, Dominion Range, Miller Range, Roberts Massif, and Sandford Cliffs. Tables are provided of the newly classified Antarctic meteorites, meteorites classified by type, and tentative pairings petrographic descriptions.

  16. Differentiation of Chitinase-Active and Non-Chitinase-Active Subpopulations of a Marine Bacterium during Chitin Degradation

    PubMed Central

    Baty, Ace M.; Eastburn, Callie C.; Diwu, Zhenjun; Techkarnjanaruk, Somkiet; Goodman, Amanda E.; Geesey, Gill G.

    2000-01-01

    The ability of marine bacteria to adhere to detrital particulate organic matter and rapidly switch on metabolic genes in an effort to reproduce is an important response for bacterial survival in the pelagic marine environment. The goal of this investigation was to evaluate the relationship between chitinolytic gene expression and extracellular chitinase activity in individual cells of the marine bacterium Pseudoalteromonas sp. strain S91 attached to solid chitin. A green fluorescent protein reporter gene under the control of the chiA promoter was used to evaluate chiA gene expression, and a precipitating enzyme-linked fluorescent probe, ELF-97–N-acetyl-β-d-glucosaminide, was used to evaluate extracellular chitinase activity among cells in the bacterial population. Evaluation of chiA expression and ELF-97 crystal location at the single-cell level revealed two physiologically distinct subpopulations of S91 on the chitin surface: one that was chitinase active and remained associated with the surface and another that was non-chitinase active and released daughter cells into the bulk aqueous phase. It is hypothesized that the surface-associated, non-chitinase-active population is utilizing chitin degradation products that were released by the adjacent chitinase-active population for cell replication and dissemination into the bulk aqueous phase. PMID:10919822

  17. Differential cold-adaptation among protein components of the thioredoxin system in the psychrophilic eubacterium Pseudoalteromonas haloplanktis TAC 125.

    PubMed

    Cotugno, Roberta; Rosaria Ruocco, Maria; Marco, Salvatore; Falasca, Patrizia; Evangelista, Giovanna; Raimo, Gennaro; Chambery, Angela; Di Maro, Antimo; Masullo, Mariorosario; De Vendittis, Emmanuele

    2009-05-01

    Thioredoxin and thioredoxin reductase from the psychrophilic eubacterium Pseudoalteromonas haloplanktis were obtained as recombinant His-tagged proteins (rPhTrx and rPhTrxR, respectively). rPhTrxR is organised as a homodimeric flavoenzyme, whereas rPhTrx is a small monomeric protein, both containing a functional disulfide bridge. However, three additional cysteines are present as free thiols in purified rPhTrxR. When individually tested in specific assays, rPhTrxR and rPhTrx display a full activity at low temperatures, an indispensable requirement for cold-adapted proteins. In particular, rPhTrxR catalyses the NADPH dependent reduction of DTNB and rPhTrx provokes the insulin precipitation in the presence of DTT. The analysis of the effect of temperature on these reactions indicates that rPhTrxR is more cold-adapted than rPhTrx, having a higher psychrophilicity. The combined activity of rPhTrxR and rPhTrx, tested in a reconstituted assay containing NADPH as electrons donor and human insulin as the thioredoxin substrate, demonstrates a direct functional interaction between the purified recombinant components of the thioredoxin system of P. haloplanktis. Furthermore, the NADPH-dependent reduction of rPhTrx catalysed by rPhTrxR is fully reversible and allows the determination of its redox potential, whose value is in the range of other bacterial and archaeal thioredoxins. The analysis of the thermostability of rPhTrxR points to its discrete heat resistance. However, rPhTrx is much more heat resistant, with a half inactivation time of about 4 h at 95 degrees C. This exceptional heat resistance for a psychrophilic protein is significantly decreased by the reduction of the disulfide bridge of rPhTrx. Functionality, thermodependence and thermostability of the P. haloplanktis thioredoxin system point to the relevance of this key mechanism for the preservation of the reduced state of cytoplasmic proteins even in a cold-adapted source.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Crystallization and preliminary X-ray diffraction studies of tetrameric malate dehydrogenase from the novel Antarctic psychrophile Flavobacterium frigidimaris KUC-1

    SciTech Connect

    Fujii, Tomomi; Oikawa, Tadao; Muraoka, Ikuo; Soda, Kenji; Hata, Yasuo

    2007-11-01

    A psychrophilic malate dehydrogenase from the novel Antarctic bacterium F. frigidimaris KUC-1 was crystallized using the hanging-drop vapour-diffusion method. The crystals contained one tetrameric molecule per asymmetric unit. The best crystal diffracted to 1.8 Å resolution. Flavobacterium frigidimaris KUC-1 is a novel psychrotolerant bacterium isolated from Antarctic seawater. Malate dehydrogenase (MDH) is an essential metabolic enzyme in the citric acid cycle and has been cloned, overexpressed and purified from F. frigidimaris KUC-1. In contrast to the already known dimeric form of MDH from the psychrophile Aquaspirillium arcticum, F. frigidimaris MDH exists as a tetramer. It was crystallized at 288 K by the hanging-drop vapour-diffusion method using ammonium sulfate as the precipitating agent. The crystal diffracted to a maximum resolution of 1.80 Å. It contains one tetrameric molecule in the asymmetric unit.

  20. Characterization of water-soluble dark-brown pigment from Antarctic bacterium, Lysobacter oligotrophicus.

    PubMed

    Kimura, Tomomi; Fukuda, Wakao; Sanada, Tomoe; Imanaka, Tadayuki

    2015-07-01

    Lysobacter oligotrophicus strain 107-E2(T) isolated from Antarctica produces dark-brown colored water-soluble pigment, in addition to hydrolases and lytic enzymes. The production of pigment is a common characteristic among members of the genus Lysobacter, but the identity of the pigments has been unknown. In this study, we identified the pigment from L. oligotrophicus as melanin pigment (Lo-melanin) by chemical and spectroscopic analyses. Although melanin is generally insoluble in both aqueous and organic solvents, the results in this study revealed that Lo-melanin shows water-solubility by means of the added polysaccharide chain. Lo-melanin production of L. oligotrophicus was increased by ultraviolet (UV) exposure, and survival rate of Escherichia coli under UV-irradiated condition was increased by the addition of Lo-melanin to the medium.

  1. Hydrocarbon degradation by antarctic bacteria

    SciTech Connect

    Cavanagh, J.A.E.; Nichols, P.D.; McMeekin, T.A.; Franzmann, P.D.

    1996-12-31

    Bacterial cultures obtained from sediment samples collected during a trial oil spill experiment conducted at Airport beach, Eastern Antarctica were selectively enriched for n-alkane-degrading and phenanthrenedegrading bacteria. Samples were collected from a control site and sites treated with different hydrocarbon mixtures - Special Antarctic blend (SAB), BP-Visco and orange roughy oils. One set of replicate sites was also treated with water from Organic Lake which had previously been shown to contain hydrocarbon-degrading bacteria. No viable bacteria were obtained from samples collected from sites treated with orange roughy oil. Extensive degradation of n-alkanes by enrichment cultures obtained from sites treated with SAB and BP-Visco occurred at both 25{degrees}C and 10{degrees}C. Extensive degradation of phenanthrene also occurred in enrichment cultures from these sites grown at 25{degrees}C. Concurrent increases of polar lipid in these cultures were also observed. The presence of 1,4-naphthaquinone and 1-naphthol during the growth of the cultures on phenanthrene is unusual and warrants further investigation of the mechanism of phenanthrene-degradation by these Antarctic bacteria.

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

    PubMed

    Huovinen, Pirjo; Ramírez, Jaime; Gómez, Iván

    2016-01-01

    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 further

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

    PubMed Central

    Huovinen, Pirjo; Ramírez, Jaime; Gómez, Iván

    2016-01-01

    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

  4. The changing form of Antarctic biodiversity.

    PubMed

    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.

  5. A "MICROTUBULE" IN A BACTERIUM

    PubMed Central

    van Iterson, Woutera; Hoeniger, Judith F. M.; van Zanten, Eva Nijman

    1967-01-01

    A study of the anchorage of the flagella in swarmers of Proteus mirabilis led to the incidental observation of microtubules. These microtubules were found in thin sections and in whole mount preparations of cells from which most of the content had been released by osmotic shock before staining negatively with potassium phosphotungstate (PTA). The microtubules are in negatively stained preparations about 200 A wide, i.e. somewhat thicker than the flagella (approximately 130 A). They are thus somewhat thinner than most microtubules recorded for other cells. They are referred to as microtubules because of their smooth cylindrical wall, or cortex, surrounding a hollow core which is readily filled with PTA when stained negatively. Since this is probably the first time that such a structure is described inside a bacterium, we do not know for certain whether it represents a normal cell constituent or an abnormality, for instance of the type of "polysheaths" (16). PMID:10976198

  6. Carbonate Deposition on Antarctic Shelves

    NASA Astrophysics Data System (ADS)

    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

  7. 77 FR 60677 - Proposed Information Collection; Comment Request; Antarctic Marine Living Resources Conservation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-04

    ... National Oceanic and Atmospheric Administration Proposed Information Collection; Comment Request; Antarctic... Antarctic Marine Living Resources (Convention) established the Commission for the Conservation of Antarctic... Convention and a member of CCAMLR and its Scientific Committee. The Antarctic Marine Living...

  8. Telemedicine in the British Antarctic survey.

    PubMed

    Grant, Iain C

    2004-12-01

    Medicine in the Antarctic is probably the most isolated situation in which a doctor can practise, differing in degree of severity even from that of the Arctic region. The increasing use of Telemedicine has helped to reduce this isolation and to improve access to secondary healthcare for those who live in the most remote bases in the world. The article describes the way in which Antarctic Telemedicine has evolved in the British Antarctic survey, outlining the use of low cost and low technology systems to improve the availability of emergency advice, both to the doctor and to isolated field parties, specialist consultation, medical education, and healthcare records. The Antarctic is a useful proving ground for technologies which may have applications in space and other extreme and isolated environments.

  9. Formation of the 1988 Antarctic ozone hole

    SciTech Connect

    Krueger, A.J.; Stolarski, R.S.; Schoeberl, M.R. )

    1989-05-01

    The 1988 Antarctic ozone hole, as observed with the Nimbus 7 TOMS instrument, formed in August but failed to deepen significantly during September. The structure of the surrounding total ozone maxima also differed from the prior year. The 1987 total ozone pattern was pole centered and symmetrical. During 1988 a persistent strong wavenumber 1 perturbation in total ozone developed in August which resulted in displacement of the polar ozone minimum to the base of the Antarctic Peninsula. Subsequently, a series of transient events diminished and a larger scale decrease in polar total ozone began. The decrease lasted less than two weeks, resulting in a net change of only 25 DU compared with the nearly 100 DU decline observed during the same period in 1987. The minimum values remained roughly constant until October 19, 1988 and then increased rapidly. The 1988 Antarctic ozone hole subsequently drifted off the Antarctic continent in late October and dissipated in mid-November.

  10. Update on Terrestrial Ages of Antarctic Meteorites

    NASA Technical Reports Server (NTRS)

    Welten, K. C.; Nishiizumi, K.; Caffee, M. W.

    2000-01-01

    Terrestial ages are presented for 70 Antarctic meteorites, based on cosmogenic Be-10, Al-26 and Cl-36 in the metal phase. Also, results of leaching experiments are discussed to study possible contamination of stony meteorites with atmospheric Be-10

  11. Update on terrestrial ages of Antarctic meteorites

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Elmore, D.; Kubik, P. W.

    1989-01-01

    Cosmic-ray produced Cl-36 (half-life = 3.01 x 10 to the 5th years) has been measured in 90 Antarctic meteorites by accelerator mass spectrometry. The terrestrial ages of the meteorites were calculated from the results. After excluding possible paired objects, 138 terrestrial ages from 18 different locations are available from C-14, Kr-81, and Cl-36 measurements for application to Antarctic meteorite and glaciological studies. The terrestrial ages of Allan Hills meteorites vary from 2000 years to 1 million years and are clearly longer than those of Yamato meteorites and other Antarctic meteorites. The oldest Allan Hills meteorites were found close to the eastern edge and in the southeast of the main icefield. Among all Antarctic meteorites measured to date, only L and LL chondrites have terrestrial ages older than 370,000 years.

  12. The Antarctic dipole and its predictability

    NASA Astrophysics Data System (ADS)

    Yuan, Xiaojun; Martinson, Douglas G.

    This study investigates the nature of interannual variability of Antarctic sea ice and its relationship with the tropical climate. We find that the dominant interannual variance structure in the sea ice edge and surface air temperature fields is organized as a quasi-stationary wave which we call the “Antarctic Dipole” (ADP). It is characterized by an out-of-phase relationship between the ice and temperature anomalies in the central/eastern Pacific and Atlantic sectors of the Antarctic. The dipole consists of a strong standing mode and a weaker propagating motion within each basin's ice field. It has the same wavelength as the Antarctic Circumpolar Wave (ACW) and dominates the ACW variance. The dipole is clearly associated with tropical ENSO events; it can be predicted with moderate skill using linear regression involving surface temperature two to four months ahead. The prediction performs better in extreme warm/cold years, and best in La Niña years.

  13. Denitrification in the Antarctic stratosphere

    NASA Technical Reports Server (NTRS)

    Salawitch, R. J.; Gobbi, G. P.; Wofsy, S. C.; Mcelroy, M. B.

    1989-01-01

    Rapid loss of ozone over Antarctica in spring requires that the abundance of gaseous nitric acid be very low. Precipitation of particulate nitric acid has been assumed to occur in association with large ice crystals, requiring significant removal of H2O and temperatures well below the frost point. However, stratospheric clouds exhibit a bimodal size distribution in the Antarctic atmosphere, with most of the nitrate concentrated in particles with radii of 1 micron or greater. It is argued here that the bimodal size distribution sets the stage for efficient denitrification, with nitrate particles either falling on their own or serving as nuclei for the condensation of ice. Denitrification can therefore occur without significant dehydration, and it is unnecessary for temperatures to drop significantly below the frost point.

  14. Unveiling the Antarctic subglacial landscape.

    NASA Astrophysics Data System (ADS)

    Warner, Roland; Roberts, Jason

    2010-05-01

    Better knowledge of the subglacial landscape of Antarctica is vital to reducing uncertainties regarding prediction of the evolution of the ice sheet. These uncertainties are associated with bedrock geometry for ice sheet dynamics, including possible marine ice sheet instabilities and subglacial hydrological pathways (e.g. Wright et al., 2008). Major collaborative aerogeophysics surveys motivated by the International Polar Year (e.g. ICECAP and AGAP), and continuing large scale radar echo sounding campaigns (ICECAP and NASA Ice Bridge) are significantly improving the coverage. However, the vast size of Antarctica and logistic difficulties mean that data gaps persist, and ice thickness data remains spatially inhomogeneous. The physics governing large scale ice sheet flow enables ice thickness, and hence bedrock topography, to be inferred from knowledge of ice sheet surface topography and considerations of ice sheet mass balance, even in areas with sparse ice thickness measurements (Warner and Budd, 2000). We have developed a robust physically motivated interpolation scheme, based on these methods, and used it to generate a comprehensive map of Antarctic bedrock topography, using along-track ice thickness data assembled for the BEDMAP project (Lythe et al., 2001). This approach reduces ice thickness biases, compared to traditional inverse distance interpolation schemes which ignore the information available from considerations of ice sheet flow. In addition, the use of improved balance fluxes, calculated using a Lagrangian scheme, eliminates the grid orientation biases in ice fluxes associated with finite difference methods (Budd and Warner, 1996, Le Brocq et al., 2006). The present map was generated using a recent surface DEM (Bamber et al., 2009, Griggs and Bamber, 2009) and accumulation distribution (van de Berg et al., 2006). Comparing our results with recent high resolution regional surveys gives confidence that all major subglacial topographic features are

  15. Trace element contamination in Antarctic ecosystems.

    PubMed

    Sanchez-Hernandez, J C

    2000-01-01

    Data concerning trace element concentrations in both abiotic and biotic components of the Antarctic ecosystems are summarized here to be used as a first background database for pollution detection. Antarctic ancient ice and snow cores have been used to assess past and present-day changes in global atmospheric levels of certain trace elements. Concentrations of Pb, Cd, and Hg in the Antarctic tropospheric cell have varied according to glacial and interglacial periods before humans began to contaminate the atmosphere with these metals. Based on data of Pb concentrations in the Antarctic ancient ice cores and samples of recent snow, most of the Pb in Antarctica is anthropogenic. Moreover, this metal has decreased in recent years as a consequence of the reduced use of leaded gasoline in countries of the Southern Hemisphere. Reliable experimental and field data have indicated, however, that human activity in Antarctica contributes significantly to increasing atmospheric Pb levels in this continent, whereas the environmental impact of other metals such as Cd, Zn, or Hg is restricted to the area a few hundreds of meters about the anthropogenic source. Trace element concentrations in Antarctic abiotic matrixes are generally at ultratrace levels, challenging analytical detection limits and increasing the risk of unwanted contamination. Pb and Hg concentrations in Antarctic snow, surficial soil, air, and marine sediment have been considered as the lowest concentrations ever reported. Conversely, concentrations in Antarctic biota, are comparable to those from polar and temperate areas of the Northern Hemisphere, in particular Cd and Hg. Environmental and biological factors favoring a greater metal accumulation by Antarctic biota are discussed. Growth rate of the organisms and detoxification mechanisms (e.g., metallothioneins, molting cycles) are largely affected by the extreme environmental conditions in Antarctica (water supply, temperature regimen, light availability) that

  16. Satellites reveal Antarctic mass imbalance

    NASA Astrophysics Data System (ADS)

    Shepherd, A.

    2004-05-01

    Satellite radar observations have revealed a widespread mass imbalance in western Antarctica and rapid thinning of ice shelves at the Antarctic Peninsula. The former shows grounded ice retreat in a region previously considered unstable to such events, and the latter illuminates an ongoing debate as to the mechanism through which ice shelves have disintegrated over the past decade. Both measurements inform us as to the present state of balance of the cryosphere and its interactions with the southern oceans. Since 1992, the Amundsen Sea sector of the West Antarctic Ice Sheet has lost 39 cubic kilometers of its volume each year due to an imbalance between snow accumulation and ice discharge. A flow disturbance is responsible for removing the majority of that ice from the trunks of the Pine Island, Thwaites and Smith glacier drainage systems, raising global sea level by over 1 mm during the past decade alone. The coincidence of rapid ice thinning at the Amundsen Coast and warm circumpolar deep water intrusion in Pine Island Bay, coupled with a ~ 50 cubic kilometre annual freshening of the Ross Sea Gyre downstream, makes ocean melting an attractive proposition for the origin of the regional disturbance. At the same time, the Larsen Ice Shelf surface has lowered by up to 0.27 m per year, in tandem with a period of atmospheric warming and ice shelf collapse. The lowering cannot be explained by increased summer melt-water production alone, and must reflect a loss of basal ice through melting. Ocean temperature measurements close to the ice shelf barrier support this conclusion, making enhanced basal ice melting a likely factor linking the regional climate warming and the successive disintegration of sections of the Larsen Ice Shelf.

  17. Survival mechanisms in Antarctic lakes.

    PubMed Central

    Laybourn-Parry, Johanna

    2002-01-01

    In Antarctic lakes, organisms are confronted by continuous low temperatures as well as a poor light climate and nutrient limitation. Such extreme environments support truncated food webs with no fish, few metazoans and a dominance of microbial plankton. The key to success lies in entering the short Antarctic summer with actively growing populations. In many cases, the most successful organisms continue to function throughout the year. The few crustacean zooplankton remain active in the winter months, surviving on endogenous energy reserves and, in some cases, continuing development. Among the Protozoa, mixotrophy is an important nutritional strategy. In the extreme lakes of the McMurdo Dry Valleys, planktonic cryptophytes are forced to sustain a mixotrophic strategy and cannot survive by photosynthesis alone. The dependence on ingesting bacteria varies seasonally and with depth in the water column. In the Vestfold Hills, Pyramimonas, which dominates the plankton of some of the saline lakes, also resorts to mixotrophy, but does become entirely photosynthetic at mid-summer. Mixotrophic ciliates are also common and the entirely photosynthetic ciliate Mesodinium rubrum has a widespread distribution in the saline lakes of the Vestfold Hills, where it attains high concentrations. Bacteria continue to grow all year, showing cycles that appear to be related to the availability of dissolved organic carbon. In saline lakes, bacteria experience sub-zero temperatures for long periods of the year and have developed biochemical adaptations that include anti-freeze proteins, changes in the concentrations of polyunsaturated fatty acids in their membranes and suites of low-temperature enzymes. PMID:12171649

  18. Ross Ice Shelf, Antarctic Ice and Clouds

    NASA Technical Reports Server (NTRS)

    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.

  19. Breakup of Pack Ice, Antarctic Ice Shelf

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Breakup of Pack Ice along the periphery of the Antarctic Ice Shelf (53.5S, 3.0E) produced this mosaic of ice floes off the Antarctic Ice Shelf. Strong offshore winds, probably associated with strong katabatic downdrafts from the interior of the continent, are seen peeling off the edges of the ice shelf into long filamets of sea ice, icebergs, bergy bits and growlers to flow northward into the South Atlantic Ocean. 53.5S, 3.0E

  20. Volcanic deposits in Antarctic snow and ice

    NASA Astrophysics Data System (ADS)

    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.

  1. Differences in the degree of weathering between Antarctic and non-Antarctic meteorites inferred from infrared diffuse reflectance spectra

    NASA Astrophysics Data System (ADS)

    Miyamoto, M.

    1991-01-01

    Differences in the degree of weathering between Antarctic and non-Antarctic meteorites were evaluated on the basis of measurements of the 3-micron and 7.4-micron bands in the IR diffuse reflectance spectra of 42 Antarctic and 29 non-Antarctic meteorites. Results show that non-Antarctic ordinary chondrites exhibit significantly larger values of the integrated intensity of the 3-micron band (indicating high degree of weathering) than do Antarctic ordinary chondrite falls. The spectra of all the Antarctic ordinary chondrites, on the other hand, show the presence of the 7.4-micron bands, suggesting that weathering-produced hydrous carbonates are ubiquitous in Antarctic ordinary chondrites. The non-Antarctic ordinary chondrite falls showed very weak 7.4 micron bands, indicating only few weathering-produced hydrous carbonates.

  2. The SCAR Standing Committee on Antarctic Data Management - new directions in access to Antarctic research data

    NASA Astrophysics Data System (ADS)

    de Bruin, T.

    2009-04-01

    The SCAR Standing Committee on Antarctic Data Management (SC-ADM) was established by the Scientific Committee on Antarctic Research (SCAR) and the Council of Managers of National Antarctic Programs (COMNAP), to assist in the fulfillment of the data management obligations imposed by the Antarctic Treaty (section III.1.c): "Scientific observations and results from Antarctica shall be exchanged and made freely available." SC-ADM comprises representatives of the National Antarctic Data Centres or national points of contact. Currently 31 nations around the world are represented in SC-ADM. So far, SC-ADM has been focussing on the coordination of the Antarctic Master Directory (AMD), the internationally accessible, web-based, searchable record of Antarctic and Southern Ocean data set descriptions. The AMD is directly integrated into the international Global Change Master Directory (GCMD) to help further merge Antarctic science into global science. The AMD is a resource for scientists to advertise the data they have collected and to search for data they may need. Currently, SC-ADM is in a transition phase, moving forward to provide data access. Existing systems and web services technology will be used as much as possible, to increase efficiency and prevent 're-inventing the wheel' This poster will give an overview of this process, the current status and the expected results.

  3. Unstable Space: Mapping the Antarctic for Children in "Heroic Era" Antarctic Literature

    ERIC Educational Resources Information Center

    Moriarty, Sinead

    2017-01-01

    This article examines the Antarctic landscape as one of the last places in the world to be explored and mapped, and as one of the most changeable landscapes in the world. The mapping exercises involved in the early, heroic-era Antarctic expeditions, helped to reduce a once mysterious and unknown landscape into a known entity, something that could…

  4. The Antarctic Geospatial Information Center: Three Years of Supporting Antarctic Science and Operations

    NASA Astrophysics Data System (ADS)

    Herried, B.; Morin, P. J.; Larue, M.; Porter, C.; Niebuhr, S.; Antarctic Geospatial Information Center

    2010-12-01

    Founded in 2007, the Antarctic Geospatial Information Center (AGIC) is dedicated to supporting and promoting the United States Antarctic Program (USAP) by providing geospatial information to Antarctic science, operations, and education communities. Since its inception, AGIC contributes to Antarctic science in four significant ways: 1) by direct geospatial support of research groups to advance science, 2) by authoring maps and creating applications to facilitate better logistical support, 3) by serving as a data repository and clearinghouse for Antarctic geospatial data, 4) by providing expertise, analysis, and education to researchers, support staff, and students. This poster will showcase several products, tools, and services developed by AGIC in the past three years, including a collection of 150 ground control points in the McMurdo Dry Valleys and Ross Island, highly accurate maps in the McMurdo Sound region using satellite imagery, and an archive of historical USGS aerial photography accessed through a web-based search application.

  5. Health aspects of Antarctic tourism.

    PubMed

    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

  6. Controls and variability of solute and sedimentary fluxes in Antarctic and sub-Antarctic Environments

    NASA Astrophysics Data System (ADS)

    Zwolinski, Zbigniew

    2015-04-01

    The currently prepared SEDIBUD Book on "Source-to-Sink Fluxes in Undisturbed Cold Environments" (edited by Achim A. Beylich, John C. Dixon and Zbigniew Zwolinski and published by Cambridge University Press) is summarizing and synthesizing the achievements of the International Association of Geomorphologists` (I.A.G./A.I.G.) Working Group SEDIBUD (Sediment Budgets in Cold Environments), which has been active since 2005 (http://www.geomorph.org/wg/wgsb.html). The book comprises five parts. One of them is part about sub-Antarctic and Antarctic Environments. This part "Sub-Antarctic and Antarctic Environments" describes two different environments, namely oceanic and continental ones. Each part contains results of research on environmental drivers and rates of contemporary solute and sedimentary fluxes in selected sites. Apart from describing the environmental conditions of the whole continent of Antarctica and sub-Antarctic islands (Zb.Zwolinski, M.Kejna, A.N.Lastochkin, A.Zhirov, S.Boltramovich) this part of the book characterizes terrestrial polar oases free from multi-year ice and snow covers (Zb.Zwolinski). The detailed results of geoecological and sedimentological research come from different parts of Antarctica. Antarctic continental shelf (E.Isla) is an example of sub-Antarctic oceanic environment. South Shetlands, especially King George Island (Zb.Zwolinski, M.Kejna, G.Rachlewicz, I.Sobota, J.Szpikowski), is an example of sub-Antarctic terrestrial environment. Antarctic Peninsula (G.Vieira, M.Francelino, J.C.Fernandes) and surroundings of McMurdo Dry Valleys (W.B.Lyons, K.A.Welch, J.Levy, A.Fountain, D.McKnight) are examples of Antarctic continental environments. The key goals of the Antarctic and sub-Antarctic book chapters are following: (i) identify the main environmental drivers and rates of contemporary solute and sedimentary fluxes, and (ii) model possible effects of projected climate change on solute and sedimentary fluxes in cold climate environments

  7. 76 FR 60933 - Antarctic Conservation Act Permit Applications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-30

    ... From the Federal Register Online via the Government Publishing Office ] NATIONAL SCIENCE FOUNDATION Antarctic Conservation Act Permit Applications AGENCY: National Science Foundation. ACTION: Notice... to NSF pursuant to regulations issued under the Antarctic Conservation Act of 1978. DATES:...

  8. Cardiovascular control in Antarctic fish

    NASA Astrophysics Data System (ADS)

    Egginton, Stuart; Campbell, Hamish; Davison, William

    2006-04-01

    The capacity for synthesis and plasma levels of stress hormones in species with a range of activity patterns suggest that depressed catecholamine synthesis is typical of notothenioid fishes regardless of life style, although they are able to release extensive stores under conditions of extreme trauma. Cortisol does not appear to be an important primary stress hormone in these species. In general, vascular reactivity shows a modest α and β adrenergic tonus, but with greater potency for cholinergic and serotonergic vasoconstrictor agonists, although a dominance of vasodilatation over vasoconstriction is observed in one species. Vasomotor control mechanisms appear to be primarily a consequence of evolutionary lineage rather than low environmental temperature, but the pattern may be modified according to functional demand. These and other data confirm the cardiovascular system is dominated by cholinergic control: the heart apparently lacks adrenergic innervation, but receives inhibitory parasympathetic input that regulates heart rate (HR) by setting a resting vagal tonus. Oxygen consumption (MO 2) determined at rest and varied via specific dynamic action, in intact fish and fish that had undergone bilateral sectioning of the vagus nerve, show that HR is a good predictor of MO 2, and that the major influence on HR is the degree of vagal tone—these fish work by removing the brake rather than applying the accelerator. However, whether these traits actually represent adaptation to the Antarctic environment or merely represent ancestral characteristics and their relative phylogenetic position is at present unclear.

  9. Modelling the Antarctic lower stratosphere

    NASA Technical Reports Server (NTRS)

    Chipperfield, M. P.; Pyle, J. A.

    1988-01-01

    Results form modeling studies of the Antarctic lower stratosphere which have attempted to simulate the large springtime ozone losses and corresponding changes in other trace constituents are given. These studies were carried out in a photochemical box model, a one-dimensional model without transport and in a two-dimensional photochemical-dynamical-radiation model. The photochemical studies have investigated inter alia the sensitivity of ozone to inclusion in the model of heterogeneous chemistry, and to the inclusion of the ClO dimer. When both of these are incorporated in the model, ozone depletions resembling whose found in Halley Bay in 1987 (J.C. Farman, Nature, 329, 1987) can be reproduced. The temporal variations (both diurnal and during the August to October period) of a number of important tracers including HCl, ClONO2, OClO and BrO are discussed. The two-dimensional study concentrated on the difficulty of establishing in the model the dynamical preconditioning of the lower polar stratosphere - low temperatures, low N2O, etc., high ClOx. Calculations are presented to show: (1) the depletion of ozone during the springtime season, (2) the effect of large ozone losses on lower latitudes, and (3) the longer term (multi-year) variations of ozone in Antarctica, assuming realistic increases in the atmospheric halogen burden.

  10. Antarctic radio Askaryan neutrino telescopes

    NASA Astrophysics Data System (ADS)

    Connolly, Amy

    2012-03-01

    There are strong motivations for a detectable flux of ultra-high energy (UHE) cosmic neutrinos above 10^17-18 eV. Neutrinos in this regime are expected from interactions between the highest energy cosmic rays and cosmic microwave background photons, and can also originate from the UHE sources themselves. Radio Cerenkov technique is the most promising technique for instrumenting a detection volume large enough to detect the low expected fluxes. The RICE experiment pioneered the radio Cerenkov technique with antennas deployed along strings of the AMANDA experiment deep in the South Pole ice. New radio arrays being deployed in the Antarctic ice are designed to measure dozens of these unique cosmic messengers to exploit the rich particle physics and astrophysical information that they carry. I will discuss the status and results from initial deployments of the Askaryan Radio Array (ARA) near the South Pole, and the ARIANNA array on the Ross Ice Shelf. I will also describe how these experiments could measure neutrino-nucleon cross sections at energies that exceed those probed by the LHC.

  11. Adult antarctic krill feeding at abyssal depths.

    PubMed

    Clarke, Andrew; Tyler, Paul A

    2008-02-26

    Antarctic krill (Euphausia superba) is a large euphausiid, widely distributed within the Southern Ocean [1], and a key species in the Antarctic food web [2]. The Discovery Investigations in the early 20(th) century, coupled with subsequent work with both nets and echosounders, indicated that the bulk of the population of postlarval krill is typically confined to the top 150 m of the water column [1, 3, 4]. Here, we report for the first time the existence of significant numbers of Antarctic krill feeding actively at abyssal depths in the Southern Ocean. Biological observations from the deep-water remotely operated vehicle Isis in the austral summer of 2006/07 have revealed the presence of adult krill (Euphausia superba Dana), including gravid females, at unprecedented depths in Marguerite Bay, western Antarctic Peninsula. Adult krill were found close to the seabed at all depths but were absent from fjords close inshore. At all locations where krill were detected they were seen to be actively feeding, and at many locations there were exuviae (cast molts). These observations revise significantly our understanding of the depth distribution and ecology of Antarctic krill, a central organism in the Southern Ocean ecosystem.

  12. Antarctic teleost immunoglobulins: more extreme, more interesting.

    PubMed

    Coscia, Maria Rosaria; Varriale, Sonia; Giacomelli, Stefano; Oreste, Umberto

    2011-11-01

    We have investigated the immunoglobulin molecule and the genes encoding it in teleosts living in the Antarctic seas at the constant temperature of -1.86 °C. The majority of Antarctic teleosts belong to the suborder Notothenioidei (Perciformes), which includes only a few non-Antarctic species. Twenty-one Antarctic and two non-Antarctic Notothenioid species were included in our studies. We sequenced immunoglobulin light chains in two species and μ heavy chains, partially or totally, in twenty species. In the case of heavy chain, genomic DNA and the cDNA encoding the secreted and the membrane form were analyzed. From one species, Trematomus bernacchii, a spleen cDNA library was constructed to evaluate the diversity of VH gene segments. T. bernacchii IgM, purified from the serum and bile, was characterized. Homology Modelling and Molecular Dynamics were used to determine the molecular structure of T. bernacchii and Chionodraco hamatus immunoglobulin domains. This paper sums up the previous results and broadens them with the addition of unpublished data.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. 45 CFR 670.9 - Antarctic Conservation Act enforcement exception.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 3 2013-10-01 2013-10-01 false Antarctic Conservation Act enforcement exception... FOUNDATION CONSERVATION OF ANTARCTIC ANIMALS AND PLANTS Prohibited Acts, Exceptions § 670.9 Antarctic Conservation Act enforcement exception. Paragraphs (a) through (d) of § 670.4 shall not apply to acts...

  15. 45 CFR 670.9 - Antarctic Conservation Act enforcement exception.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Antarctic Conservation Act enforcement exception... FOUNDATION CONSERVATION OF ANTARCTIC ANIMALS AND PLANTS Prohibited Acts, Exceptions § 670.9 Antarctic Conservation Act enforcement exception. Paragraphs (a) through (d) of § 670.4 shall not apply to acts...

  16. 45 CFR 670.9 - Antarctic Conservation Act enforcement exception.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 3 2011-10-01 2011-10-01 false Antarctic Conservation Act enforcement exception... FOUNDATION CONSERVATION OF ANTARCTIC ANIMALS AND PLANTS Prohibited Acts, Exceptions § 670.9 Antarctic Conservation Act enforcement exception. Paragraphs (a) through (d) of § 670.4 shall not apply to acts...

  17. 45 CFR 670.9 - Antarctic Conservation Act enforcement exception.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 3 2014-10-01 2014-10-01 false Antarctic Conservation Act enforcement exception... FOUNDATION CONSERVATION OF ANTARCTIC ANIMALS AND PLANTS Prohibited Acts, Exceptions § 670.9 Antarctic Conservation Act enforcement exception. Paragraphs (a) through (d) of § 670.4 shall not apply to acts...

  18. 45 CFR 670.9 - Antarctic Conservation Act enforcement exception.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 3 2012-10-01 2012-10-01 false Antarctic Conservation Act enforcement exception... FOUNDATION CONSERVATION OF ANTARCTIC ANIMALS AND PLANTS Prohibited Acts, Exceptions § 670.9 Antarctic Conservation Act enforcement exception. Paragraphs (a) through (d) of § 670.4 shall not apply to acts...

  19. The Antarctic cryptoendolithic ecosystem: relevance to exobiology.

    PubMed

    Friedmann, E I; Ocampo-Friedmann, R

    1984-01-01

    Cryptoendolithic microorganisms in the Antarctic desert live inside porous sandstone rocks, protected by a thin rock crust. While the rock surface is abiotic, the microclimate inside the rock is comparatively mild. These organisms may have descended from early, pre-glaciation Antarctic life forms and thus may represent the last outpost of life in a gradually deteriorating environment. Assuming that life once arose on Mars, it is conceivable that, following the loss of water, the last of surviving organisms withdrew to similar insulated microenvironments. Because such microscopic pockets have little connection with the outside environment, their detection may be difficult. The chances that the Viking lander could sample cryptoendolithic microorganisms in the Antarctic desert would be infinitesimal.

  20. NSF's role in Antarctic environment scrutinized

    NASA Astrophysics Data System (ADS)

    Bush, Susan

    In the last few years, the National Science Foundation has come under criticism by environmental groups for inadequate stewardship in the U.S. Antarctic Program's environmental issues. Since 1978, NSF was given full responsibility, by Executive Order, for budgeting and managing the entire U.S. national program in Antarctica, including logistics support. NSF has also been responsible for the compliance of the U.S. Antarctic Program with environmental protection measures agreed to by the Antarctic Treaty nations. Specifically under fire by environmentalists have been NSF's maintenance of a land-fill, open-air burning of solid waste, and the removal of toxic substances. According to Peter E. Wilkniss, director of the Division of Polar Programs at NSF, open burning is no longer taking place and will not be allowed in the future.

  1. Antarctic “quiet” site stirs debate

    NASA Astrophysics Data System (ADS)

    Simarski, Lynn Teo

    Geophysicists from the United States and New Zealand plan to meet in the coming months to assess the electromagnetic pollution of an Antarctic site especially designated for research. U.S. scientists charge that a satellite Earth station erected apparently inside the preserve by New Zealand's Telecom company could interfere with experiments on the ionosphere and magnetosphere (Eos, April 28, 1992). The Site of Special Scientific Interest at Arrival Heights, the only Antarctic preserve specifically for physical science, is located near the U.S. McMurdo and New Zealand Scott bases.Debate over the Telecom facility inter-twines diplomatic and scientific issues. One question is whether the station violates the Antarctic treaty. Secondly, does it actually impair research at the site—or could it harm future experiments? To deepen the imbroglio, those involved from both nations say that transmissions from sources off-site also interfere with research—raising doubts about how pristine the site really is.

  2. Solar flare irradiation records in Antarctic meteorites

    NASA Technical Reports Server (NTRS)

    Goswami, J. N.

    1981-01-01

    The observation of tracks from solar flare heavy nuclei in Antarctic meteorite samples is reported. In an analysis of nuclear track densities in eight L and H chondrites of low metamorphic grade, it was found that two interior specimens of sample 77216, an L-3 chondrite, contain olivine grains with track densities much higher than the average track densities, indicating precompaction irradiation by solar flares in different shielding conditions. Preliminary data from mass spectroscopic analyses show a large excess of noble gases, with a Ne-20/Ne-22 ratio of greater than or equal to 10, indicating the presence of solar-type noble gas. Results of track density measurements in the other Antarctic meteorites range from 10,000 to 4,000,000/sq cm, which is within the range observed in non-Antarctic L-group meteorites

  3. Radar sensor for an autonomous Antarctic explorer

    NASA Astrophysics Data System (ADS)

    Foessel, Alex; Apostolopoulos, Dimi; Whittaker, William L.

    1999-01-01

    The localization and identification of antarctic meteorites is a task of great scientific interest and with implications to planetary exploration. Autonomous search for antarctic meteorites presents a profound technical challenge. Ground Penetrating Radar (GPR) holds the prospect to safeguard antarctic robot from terrain dangers and detect subsurface objects. In January 1998, we validated a 500 MHz GPR sensor as part of a field robotic technology demonstration at Patriot Hills, Antarctica. We deployed the sensor from a sled and integrate with position and attitude instruments to perform field measurements. Data was acquired under different conditions and in multiple locations. The radar detected hidden crevasses from 50 cm. distance, thus showing its merit as a rover safeguarding device. It also localized 5 cm. rocks ins now and ice. Moreover, the radar data was used to characterize snow/ice/bedrock stratigraphy. GPR position measurements enabled ground truth and mapping of the location of hazards and interesting subsurface objects and features.

  4. When Will the Antarctic Ozone Hole Recover?

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.

    2006-01-01

    The Antarctic ozone hole demonstrates large-scale, man-made affects on our atmosphere. Surface observations now show that human produced ozone depleting substances (ODSs) are declining. The ozone hole should soon start to diminish because of this decline. In this talk we will demonstrate an ozone hole parametric model. This model is based upon: 1) a new algorithm for estimating 61 and Br levels over Antarctica and 2) late-spring Antarctic stratospheric temperatures. This parametric model explains 95% of the ozone hole area's variance. We use future ODS levels to predict ozone hole recovery. Full recovery to 1980 levels will occur in approximately 2068. The ozone hole area will very slowly decline over the next 2 decades. Detection of a statistically significant decrease of area will not occur until approximately 2024. We further show that nominal Antarctic stratospheric greenhouse gas forced temperature change should have a small impact on the ozone hole.

  5. When will the Antarctic ozone hole recover?

    NASA Astrophysics Data System (ADS)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Stephen A.; Schauffler, Sue M.

    2006-06-01

    The Antarctic ozone hole demonstrates large-scale, man-made affects on our atmosphere. Surface observations now show that human produced ozone-depleting substances (ODSs) are declining. The ozone hole should soon start to diminish because of this decline. We demonstrate a parametric model of ozone hole area that is based upon a new algorithm for estimating chlorine and bromine levels over Antarctica and late spring Antarctic stratospheric temperatures. This model explains 95% of the ozone hole area's variance. We then use future ODS levels to predict ozone hole recovery. Full recovery to 1980 levels will occur around 2068 and the area will very slowly decline between 2001 and 2017. Detection of a statistically significant decrease of area will not occur until about 2024. We further show that nominal Antarctic stratospheric greenhouse gas forced temperature change should have a small impact on the ozone hole.

  6. When Will the Antarctic Ozone Hole Recover?

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Stephen A.; Schauffler, Sue

    2006-01-01

    The Antarctic ozone hole demonstrates large-scale, man-made affects on our atmosphere. Surface observations now show that human produced ozone depleting substances (ODSs) are declining. The ozone hole should soon start to diminish because of this decline. Herein we demonstrate an ozone hole parametric model. This model is based upon: 1) a new algorithm for estimating C1 and Br levels over Antarctica and 2) late-spring Antarctic stratospheric temperatures. This parametric model explains 95% of the ozone hole area s variance. We use future ODS levels to predict ozone hole recovery. Full recovery to 1980 levels will occur in approximately 2068. The ozone hole area will very slowly decline over the next 2 decades. Detection of a statistically significant decrease of area will not occur until approximately 2024. We further show that nominal Antarctic stratospheric greenhouse gas forced temperature change should have a small impact on the ozone hole.

  7. Reconsidering connectivity in the sub-Antarctic.

    PubMed

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

    2017-03-29

    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.

  8. Sublgacial Antarctic Lake Environments (SALE)

    NASA Astrophysics Data System (ADS)

    Kennicutt, M. C.; Bell, R. E.; Priscu, J. C.

    2004-12-01

    Subglacial Antarctic lake environments are emerging as one of the new frontiers targeted for exploration during the IPY 2007-2009. Several campaigns by various nations are in the early stages of planning and implementation with timelines that will coincide with the IPY. The ambitious interdisciplinary objectives will best be realized by multiple exploration programs investigating diverse subglacial environments continent-wide over the next decade or more. A concerted, multi-target approach wil be taken to advance our understanding of the range of possible lake evolutionary histories; the character of the physical, chemical, and biological niches; the interconnectivity of subglacial lake environments; the coupling of the ice sheet, climate and the evolution of life under the ice; the tectonic settings; and the interplay of biogeochemical cycles. Research and exploration programs spanning the continent will investigate subglacial lake environments of differing ages, evolutionary histories, and biogeochemical settings. The combined efforts will provide a holistic view of these environments over millions of years and under changing climatic conditions. The IPY will provide an opportunity for an intense period of initial exploration that will advance scientific discoveries in glaciology, biogeochemistry, paleoclimate, biology, geology and tectonics, and ecology. While early discoveries and exciting findings are expected during the IPY 2007-2009, a long term sustained program of research and exploration will continue far beyond the IPY. Within the five year period that spans the IPY, specific accomplishments will be targeted, accelerating the research agenda and setting a framework for follow-on studies. Four phases of exploration and discovery are envisioned.

  9. Primary Production in Antarctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Arrigo, Kevin R.; Worthen, Denise L.; Lizotte, Michael P.; Dixon, Paul; Dieckmann, Gerhard

    1997-01-01

    A numerical model shows that in Antarctic sea ice, increased flooding in regions with thick snow cover enhances primary production in the infiltration (surface) layer. Productivity in the freeboard (sea level) layer is also determined by sea ice porosity, which varies with temperature. Spatial and temporal variation in snow thickness and the proportion of first-year ice thus determine regional differences in sea ice primary production. Model results show that of the 40 tera-grams of carbon produced annually in the Antarctic ice pack, 75 percent was associated with first-year ice and nearly 50 percent was produced in the Weddell Sea.

  10. Antarctic Meteorite Newsletter, Volume 8, Number 2

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Requests for samples are welcomed from research scientists of all countries, regardless of their current state of funding for meteorite studies. All sample requests will be reviewed by the Meteorite Working Group (MWG), a peer-review committee that guides the collection, curation, allocation, and distribution of the U.S. Antarctic meteorites. Issurance of samples does not imply a commitment by any agency to fund the proposed research. Requests for financial support must be submitted separately to the appropriate funding agencies. As a matter of policy, U.S. Antarctic meteorites are the property of the National Science Foundation and all allocations are subject to recall.

  11. Environmental change and Antarctic seabird populations.

    PubMed

    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.

  12. First geomagnetic measurements in the Antarctic region

    NASA Astrophysics Data System (ADS)

    Raspopov, O. M.; Demina, I. M.; Meshcheryakov, V. V.

    2014-05-01

    Based on data from literature and archival sources, we have further processed and analyzed the results of geomagnetic measurements made during the 1772-1775 Second World Expedition by James Cook and the 1819-1821 overseas Antarctic Expedition by Russian mariners Bellingshausen and Lazarev. Comparison with the GUFM historical model showed that there are systematic differences in the spatial structure of both the declination and its secular variation. The results obtained can serve as a basis for the construction of regional models of the geomagnetic field for the Antarctic region.

  13. Mysterious iodine-overabundance in Antarctic meteorites

    NASA Technical Reports Server (NTRS)

    Dreibus, G.; Waenke, H.; Schultz, L.

    1986-01-01

    Halogen as well as other trace element concentrations in meteorite finds can be influenced by alteration processes on the Earth's surface. The discovery of Antarctic meteorites offered the opportunity to study meteorites which were kept in one of the most sterile environment of the Earth. Halogen determination in Antartic meteorites was compared with non-Antarctic meteorites. No correlation was found between iodine concentration and the weathering index, or terrestrial age. The halogen measurements indicate a contaminating phase rich in iodine and also containing chlorine. Possible sources for this contamination are discussed.

  14. Antarctic ozone - Meteoric control of HNO3

    NASA Technical Reports Server (NTRS)

    Prather, Michael J.; Rodriguez, Jose M.

    1988-01-01

    Atmospheric circulation leads to an accumulation of debris from meteors in the Antarctic stratosphere at the beginning of austral spring. The major component of meteoric material is alkaline, comprised predominantly of the oxides of magnesium and iron. These metals may neutralize the natural acidity of stratospheric aerosols, remove nitric acid from the gas phase, and bond it as metal nitrates in the aerosol phase. Removal of nitric acid vapor has been previously shown to be a critical link in the photochemical depletion of ozone in the Antarctic spring, by allowing for increased catalytic loss from chlorine and bromine.

  15. Climate Change Influences on Antarctic Bird Populations

    NASA Astrophysics Data System (ADS)

    Korczak-Abshire, Małgorzata

    2010-01-01

    Rapid changes in the major environmental variables like: temperature, wind and precipitation have occurred in the Antarctic region during the last 50 years. In this very sensitive region, even small changes can potentially lead to major environmental perturbations. Then the climate change poses a new challenge to the survival of Antarctic wildlife. As important bioindicators of changes in the ecosystem seabirds and their response to the climate perturbations have been recorded. Atmospheric warming and consequent changes in sea ice conditions have been hypothesized to differentially affect predator populations due to different predator life-history strategies and substantially altered krill recruitment dynamics.

  16. Primary Production in Antarctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Arrigo, Kevin R.; Worthen, Denise L.; Lizotte, Michael P.; Dixon, Paul; Dieckmann, Gerhard

    1997-01-01

    A numerical model shows that in Antarctic sea ice, increased flooding in regions with thick snow cover enhances primary production in the infiltration (surface) layer. Productivity in the freeboard (sea level) layer is also determined by sea ice porosity, which varies with temperature. Spatial and temporal variation in snow thickness and the proportion of first-year ice thus determine regional differences in sea ice primary production. Model results show that of the 40 tera-grams of carbon produced annually in the Antarctic ice pack, 75 percent was associated with first-year ice and nearly 50 percent was produced in the Weddell Sea.

  17. Significant warming of the Antarctic winter troposphere.

    PubMed

    Turner, J; Lachlan-Cope, T A; Colwell, S; Marshall, G J; Connolley, W M

    2006-03-31

    We report an undocumented major warming of the Antarctic winter troposphere that is larger than any previously identified regional tropospheric warming on Earth. This result has come to light through an analysis of recently digitized and rigorously quality controlled Antarctic radiosonde observations. The data show that regional midtropospheric temperatures have increased at a statistically significant rate of 0.5 degrees to 0.7 degrees Celsius per decade over the past 30 years. Analysis of the time series of radiosonde temperatures indicates that the data are temporally homogeneous. The available data do not allow us to unambiguously assign a cause to the tropospheric warming at this stage.

  18. Trace elements in Antarctic meteorites: Weathering and genetic information

    NASA Technical Reports Server (NTRS)

    Lipschutz, M. E.

    1986-01-01

    Antarctic meteorite discoveries have created great scientific interest due to the large number of specimens recovered (approximately 7000) and because included are representatives of hitherto rare or unknown types. Antarctic meteorites are abundant because they have fallen over long periods and were preserved, transported, and concentrated by the ice sheets. The weathering effects on the Antarctic meteorites are described. Weathering effects of trace element contents of H5 chondrites were studied in detail. The results are examined. The properties of Antarctic finds and non-Antarctic falls are discussed.

  19. Activation of macrophages by an exopolysaccharide isolated from Antarctic Psychrobacter sp. B-3

    NASA Astrophysics Data System (ADS)

    Yu, Leiye; Sun, Guojie; Wei, Jingfang; Wang, Yingze; Du, Chao; Li, Jiang

    2016-09-01

    An exopolysaccharide (EPS) was isolated and purified from an Antarctic psychrophilic bacterium B-3, identified as Psychrobacter sp., and the activation of RAW264.7 cells by B-3 EPS was investigated. The results show that B-3 EPS, over a certain concentration range, promoted cell viability, nitric oxide production, tumor necrosis factor (TNF)α secretion, and phagocytic ability. Furthermore, TAK-242, an inhibitor of the toll-like receptor 4 (TLR4) significantly reduced nitric oxide production by these cells after stimulation with B-3 EPS. Moreover, B-3 EPS induced p65 phosphorylation and IκBα degradation in these cells. In conclusion, B-3 EPS might have activated RAW264.7 cells by combining with TLR4 on cell surface and triggering activation of NF-κB signaling pathways, implying that this EPS could activate macrophages and regulate initial immune response.

  20. Proceedings of a workshop on Differences Between Antarctic and Non-Antarctic Meteorites

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian (Editor); Cassidy, William A. (Editor)

    1989-01-01

    The known facts, together with new research results are reviewed, in order to examine apparent differences between the Antarctic and non-Antarctic populations. In view of the statistically significant number of Antarctic meteorites, and the existence of rare or previously unknown types of meteorites among the Antarctic meteorite collection, the question was really not so much whether there are differences, but to define which ones are significant and what their origin is. Two main causes for the possible differences have been suggested previously, namely differences in the meteorite parent populations and secondary effects (e.g., weathering). The workshop was structured to contain sessions on chemical, isotopic, petrological, and mineralogical studies of meteorites from the two collections; terrestrial age determinations; discussions on mass frequency distributions; relative abundances of meteorite types; and terrestrial meteorite flux rates and their possible changes with time.

  1. Identification of structural and morphogenesis genes of Pseudoalteromonas phage φRIO-1 and placement within the evolutionary history of Podoviridae.

    PubMed

    Hardies, Stephen C; Thomas, Julie A; Black, Lindsay; Weintraub, Susan T; Hwang, Chung Y; Cho, Byung C

    2016-02-01

    The virion proteins of Pseudoalteromonas phage φRIO-1 were identified and quantitated by mass spectrometry and gel densitometry. Bioinformatic methods customized to deal with extreme divergence defined a φRIO-1 tail structure homology group of phages, which was further related to T7 tail and internal virion proteins (IVPs). Similarly, homologs of tubular tail components and internal virion proteins were identified in essentially all completely sequenced podoviruses other than those in the subfamily Picovirinae. The podoviruses were subdivided into several tail structure homology groups, in addition to the RIO-1 and T7 groups. Molecular phylogeny indicated that these groups all arose about the same ancient time as the φRIO-1/T7 split. Hence, the T7-like infection mechanism involving the IVPs was an ancestral property of most podoviruses. The IVPs were found to variably host both tail lysozyme domains and domains destined for the cytoplasm, including the N4 virion RNA polymerase embedded within an IVP-D homolog.

  2. Targeted Capture and Heterologous Expression of the Pseudoalteromonas Alterochromide Gene Cluster in Escherichia coli Represents a Promising Natural Product Exploratory Platform

    PubMed Central

    2015-01-01

    Marine pseudoalteromonads represent a very promising source of biologically important natural product molecules. To access and exploit the full chemical capacity of these cosmopolitan Gram-(−) bacteria, we sought to apply universal synthetic biology tools to capture, refactor, and express biosynthetic gene clusters for the production of complex organic compounds in reliable host organisms. Here, we report a platform for the capture of proteobacterial gene clusters using a transformation-associated recombination (TAR) strategy coupled with direct pathway manipulation and expression in Escherichia coli. The ∼34 kb pathway for production of alterochromide lipopeptides by Pseudoalteromonas piscicida JCM 20779 was captured and heterologously expressed in E. coli utilizing native and E. coli-based T7 promoter sequences. Our approach enabled both facile production of the alterochromides and in vivo interrogation of gene function associated with alterochromide’s unusual brominated lipid side chain. This platform represents a simple but effective strategy for the discovery and biosynthetic characterization of natural products from marine proteobacteria. PMID:25140825

  3. Identification of structural and morphogenesis genes of Pseudoalteromonas phage φRIO-1 and placement within the evolutionary history of Podoviridae

    PubMed Central

    Hardies, Stephen C.; Thomas, Julie A.; Black, Lindsay; Weintraub, Susan T.; Hwang, Chung Y.; Cho, Byung C.

    2016-01-01

    The virion proteins of Pseudoalteromonas phage φRIO-1 were identified and quantitated by mass spectrometry and gel densitometry. Bioinformatic methods customized to deal with extreme divergence defined a φRIO-1 tail structure homology group of phages, which was further related to T7 tail and internal virion proteins (IVPs). Similarly, homologs of tubular tail components and internal virion proteins were identified in essentially all completely sequenced podoviruses other than those in the subfamily Picovirinae. The podoviruses were subdivided into several tail structure homology groups, in addition to the RIO-1 and T7 groups. Molecular phylogeny indicated that these groups all arose about the same ancient time as the φRIO-1/T7 split. Hence, the T7-like infection mechanism involving the IVPs was an ancestral property of most podoviruses. The IVPs were found to variably host both tail lysozyme domains and domains destined for the cytoplasm, including the N4 virion RNA polymerase embedded within an IVP-D homolog. PMID:26748333

  4. Overexpression and secretion of AgaA7 from Pseudoalteromonas hodoensis sp. nov in Bacillus subtilis for the depolymerization of agarose.

    PubMed

    Ramos, Kristine Rose M; Valdehuesa, Kris Niño G; Cabulong, Rhudith B; Moron, Llewelyn S; Nisola, Grace M; Hong, Soon-Kwang; Lee, Won-Keun; Chung, Wook-Jin

    2016-08-01

    Interest in agar or agarose-based pharmaceutical products has driven the search for potent agarolytic enzymes. An extracellular β-agarase (AgaA7) recently isolated from Pseudoalteromonas hodoensis sp. nov was expressed in Bacillus subtilis, which was chosen due to its capability to overproduce and secrete functional enzymes. Phenotypic analysis showed that the engineered B. subtilis secreted a functional AgaA7 when fused with the aprE signal peptide (SP) at the amino-terminus. The maximum agarolytic activity was observed during the late logarithmic phase. To further improve the secretion of AgaA7, an expression library of AgaA7 fused to different naturally occurring B. subtilis SPs was created. The amount of AgaA7 secreted by the clones was compared through activity assay, immuno-blot, and purification via affinity chromatography. Although the aprE SP can readily facilitate the secretion of AgaA7, other SPs such as yqgA, pel, and lipA were relatively more efficient. Among these SPs, lipA was the most efficient in improving the secretion of AgaA7.The use of B. subtilis as host for the expression and secretion of agarolytic and other hydrolytic enzymes can be a useful tool in the field of white biotechnology.

  5. Biogeography of Antarctic sea anemones (Anthozoa, Actiniaria): What do they tell us about the origin of the Antarctic benthic fauna?

    NASA Astrophysics Data System (ADS)

    Rodríguez, E.; López-González, P. J.; Gili, J. M.

    2007-08-01

    The present study of the biogeography of the Antarctic sea anemone fauna is based on new records and redescriptions of material collected from the Weddell Sea and Peninsula Antarctica, and on an update of the bibliographic data of the Antarctic and sub-Antarctic regions. The faunal compositions at different levels, the geographic and bathymetric distributions of the sea anemone fauna, and the affinities within the continent and with the sub-Antarctic fauna have been studied. Furthermore, the relationships of the sea anemone fauna, of the Southern Ocean, the Mediterranean Sea and Hawaii have been analysed. In this context, the origin of the Antarctic benthic fauna is discussed.

  6. Antarctic Data Management as Part of the IPY Legacy

    NASA Astrophysics Data System (ADS)

    de Bruin, T.

    2006-12-01

    The Antarctic Treaty states that "scientific observations and results from Antarctica shall be exchanged and made freely available". Antarctica includes the Southern Ocean. In support of this, National Antarctic Data Centres (NADC) are being established to catalogue data sets and to provide information on data sets to scientists and others with interest in Antarctic science. The Joint Committee on Antarctic Data Management (JCADM) was established by the Scientific Committee on Antarctic Research (SCAR) and the Council of Managers of National Antarctic Programs (COMNAP). JCADM comprises representatives of the National Antarctic Data Centres. Currently 30 nations around the world are represented in JCADM. JCADM is responsible for the Antarctic Master Directory (AMD), the internationally accessible, web-based, searchable record of Antarctic and Southern Ocean data set descriptions. The AMD is directly integrated into the international Global Change Master Directory (GCMD) to help further merge Antarctic science into global science. The AMD is a resource for scientists to advertise the data they have collected and to search for data they may need. JCADM is the Antarctic component of the IPY Data Infrastructure, which is presently being developed. This presentation will give an overview of the organization of Antarctic and Southern Ocean data management with sections on the organizational structure of JCADM, contents of the Antarctic Master Directory, relationships to the SCAR Scientific Research Programmes (SRP) and IPY, international embedding and connections with discipline-based peer organizations like the International Oceanographic Data and Information Exchange Committee (IODE). It will focus primarily on the role that an existing infrastructure as JCADM, may play in the development of the IPY Data Infrastructure and will provide considerations for IPY data management, based on the experiences in Antarctic and oceanographic data management.

  7. Natural Products from Antarctic Colonial Ascidians of the Genera Aplidium and Synoicum: Variability and Defensive Role

    PubMed Central

    Núñez-Pons, Laura; Carbone, Marianna; Vázquez, Jennifer; Rodríguez, Jaime; Nieto, Rosa María; Varela, María Mercedes; Gavagnin, Margherita; Avila, Conxita

    2012-01-01

    Ascidians have developed multiple defensive strategies mostly related to physical, nutritional or chemical properties of the tunic. One of such is chemical defense based on secondary metabolites. We analyzed a series of colonial Antarctic ascidians from deep-water collections belonging to the genera Aplidium and Synoicum to evaluate the incidence of organic deterrents and their variability. The ether fractions from 15 samples including specimens of the species A. falklandicum, A. fuegiense, A. meridianum, A. millari and S. adareanum were subjected to feeding assays towards two relevant sympatric predators: the starfish Odontaster validus, and the amphipod Cheirimedon femoratus. All samples revealed repellency. Nonetheless, some colonies concentrated defensive chemicals in internal body-regions rather than in the tunic. Four ascidian-derived meroterpenoids, rossinones B and the three derivatives 2,3-epoxy-rossinone B, 3-epi-rossinone B, 5,6-epoxy-rossinone B, and the indole alkaloids meridianins A–G, along with other minoritary meridianin compounds were isolated from several samples. Some purified metabolites were tested in feeding assays exhibiting potent unpalatabilities, thus revealing their role in predation avoidance. Ascidian extracts and purified compound-fractions were further assessed in antibacterial tests against a marine Antarctic bacterium. Only the meridianins showed inhibition activity, demonstrating a multifunctional defensive role. According to their occurrence in nature and within our colonial specimens, the possible origin of both types of metabolites is discussed. PMID:23015772

  8. Immune response of the Antarctic teleost Trematomus bernacchii to immunization with Psychrobacter sp. (TAD1).

    PubMed

    Buonocore, Francesco; Bernini, Chiara; Coscia, Maria Rosaria; Giacomelli, Stefano; de Pascale, Donatella; Randelli, Elisa; Stocchi, Valentina; Scapigliati, Giuseppe

    2016-09-01

    Adult Trematomus bernacchii have been immunized intraperitoneally with heat-killed cells of the Antarctic marine bacterium Psychrobacter sp. (TAD1) up to 60 days. After immunizations and sampling at various times, fish sera were tested for specific IgM by ELISA, and different tissues (head kidney and spleen) were investigated for transcription of master genes of the acquired immune response (IgM, IgT, TRβ, TRγ). Results from ELISA assays showed a time-dependent induction of specific serum anti-TAD1 IgM, and western blot analysis of TAD1 lysates probed with fish sera revealed enhanced immunoreactivity in immunized animals compared to controls. Quantitative PCR analysis of transcripts coding for IgM, IgT, TRβ, TRγ was performed in T. bernacchii tissues to assess basal expression, and then on cDNAs of cells from head kidney and spleen of fish injected for 8, 24, and 72 h with inactivated TAD1. The results showed a differential basal expression of transcripts in the examined tissues, and a time-dependent strong up-regulation of IgT, TRβ, TRγ genes upon in vivo stimulation with TAD1. These results represent a first in vivo study on the mounting of a specific immune response in an Antarctic teleost species. Copyright © 2016. Published by Elsevier Ltd.

  9. Relevance of antarctic microbial ecosystems to exobiology

    NASA Technical Reports Server (NTRS)

    Mckay, Christopher P.

    1993-01-01

    Antarctic microbial ecosystems which provide biological and physical analogs that can be used in exobiology are studied. Since the access to extraterrestrial habitats is extremely difficult, terrestrial analogs represent the best opportunity for both formulation and preliminary testing of hypothesis about life. Antarctica, as one of few suitable environments on earth is considered to be a major locus of progress in exobiology.

  10. Climate sensitivity of the Antarctic ventilation

    NASA Astrophysics Data System (ADS)

    Ito, T.; Lynch-Stieglitz, J.

    2014-12-01

    Simple box models of ocean-atmosphere carbon cycle predict that Antarctic ventilation can regulate the steady-state atmospheric CO2 through its control over the biological carbon storage in the deep ocean. A weakened upwelling would lead to a more complete nutrient utilization at the surface and an increased retention of biogenic carbon in the deep ocean. We perform a suite of numerical sensitivity experiments using a coupled seaice and global ocean circulation model to better understand what regulates the Antarctic ventilation and its link to glacial climate. The model is first spun up with a modern climatological surface forcing, which exhibits a multi-decadal oscillation, where the Southern Ocean is heated from below through the influx of warm and salty North Atlantic Deep Water, and the accumulation of heat induces intermittent convective overturning. Through the sensitivity experiments, we explore and illustrate the rich and complex behavior of the Antarctic ventilation and its response to the northern sinking, the surface wind stress, and the global mean temperature. When the northern sinking is weakened by a freshwater perturbation, the intermittent convection events are suppressed as the heat source is reduced. When the atmospheric temperature is lowered uniformly, the Antarctic seaice extent increases and the southern overturning weakens on centennial timescales. However, the convective overturning rebounds on the millennial timescale if the northern sinking is active. We will discuss implications of our results to the deep ventilation of the Southern Ocean and its impact on the ocean carbon storage.

  11. The Seasonality of Antarctic Sea Ice Trends

    NASA Astrophysics Data System (ADS)

    Holland, P.

    2014-12-01

    Unlike the strong decline in Arctic sea ice, Antarctic sea ice is experiencing a weak overall increase in area that is the residual of opposing regional trends. This study considers the seasonal pattern of these trends. In addition to traditional ice concentration and ice area, temporal rates of change of these quantities are investigated ("intensification" and "expansion," respectively). This is crucial to the attribution of the Antarctic sea ice trends, since changes in wind or thermal forcing directly affect ice areal change, rather than ice area itself. The study shows that diverse regional trends all contribute significantly to the overall Antarctic sea-ice increase. In contrast to the widely-held view of a 'south Pacific dipole', trends in the Weddell and Amundsen-Bellingshausen regions are found to best compensate in magnitude and seasonality. Perhaps most importantly, the largest concentration trends, in autumn, are actually caused by intensification trends during spring. Autumn intensification trends directly oppose autumn concentration trends in most places, seemingly as a result of ice and ocean feedbacks. Further study of changes during the spring melting season is therefore required to unravel the Antarctic sea ice increase.

  12. Development of the Circum-Antarctic Current

    USGS Publications Warehouse

    Kennett, J.P.; Houtz, R.E.; Andrews, P.B.; Edwards, A.R.; Gostin, V.A.; Hajos, M.; Hampton, M.A.; Jenkins, D.G.; Margolis, S.V.; Ovenshine, A.T.; Perch-Nielsen, K.

    1974-01-01

    Deep-sea drilling in the Southern Ocean south of Australia and New Zealand shows that the Circum-Antarctic Current developed about 30 million years ago in the middle to late Oligocene when final separation occurred between Antarctica and the continental Soulth Tasman Rise. Australia had commenced drifting northward from Antarctica 20 million years before this.

  13. Development of the circum-antarctic current.

    PubMed

    Kennett, J P; Houtz, R E; Andrews, P B; Edwards, A R; Gostin, V A; Hajos, M; Hampton, M A; Jenkins, D G; Margolis, S V; Ovenshine, A T; Perch-Nielsen, K

    1974-10-11

    Deep-sea drilling in the Southern Ocean south of Australia and New Zealand shows that the Circum-Antarctic Current developed about 30 million years ago in the middle to late Oligocene when final separation occurred between Antarctica and the continental South Tasman Rise. Australia had commenced drifting northward from Antarctica 20 million years before this.

  14. Sampling Interplanetary Dust Particles from Antarctic Air

    NASA Astrophysics Data System (ADS)

    Taylor, S.; Lever, J. H.; Alexander, C. M. O'D.; Brownlee, D. E.; Messenger, S.; Littler, L. R.; Stroud, R. M.; Wozniakiewicz, P.; Clement, S.

    2016-08-01

    We are undertaking a NASA and NSF supported project to filter large volumes of clean Antarctic air to collect a broad range of cosmic dust, including CP-IDPs, rare ultra-carbonaceous particles and particles derived from specific meteor streams.

  15. Antarctic climate cooling and terrestrial ecosystem response.

    PubMed

    Doran, Peter T; Priscu, John C; Lyons, W Berry; Walsh, John E; Fountain, Andrew G; McKnight, Diane M; Moorhead, Daryl L; Virginia, Ross A; Wall, Diana H; Clow, Gary D; Fritsen, Christian H; McKay, Christopher P; Parsons, Andrew N

    2002-01-31

    The average air temperature at the Earth's surface has increased by 0.06 degrees C per decade during the 20th century, and by 0.19 degrees C per decade from 1979 to 1998. Climate models generally predict amplified warming in polar regions, as observed in Antarctica's peninsula region over the second half of the 20th century. Although previous reports suggest slight recent continental warming, our spatial analysis of Antarctic meteorological data demonstrates a net cooling on the Antarctic continent between 1966 and 2000, particularly during summer and autumn. The McMurdo Dry Valleys have cooled by 0.7 degrees C per decade between 1986 and 2000, with similar pronounced seasonal trends. Summer cooling is particularly important to Antarctic terrestrial ecosystems that are poised at the interface of ice and water. Here we present data from the dry valleys representing evidence of rapid terrestrial ecosystem response to climate cooling in Antarctica, including decreased primary productivity of lakes (6-9% per year) and declining numbers of soil invertebrates (more than 10% per year). Continental Antarctic cooling, especially the seasonality of cooling, poses challenges to models of climate and ecosystem change.

  16. Contrasts between Antarctic and Arctic ozone depletion.

    PubMed

    Solomon, Susan; Portmann, Robert W; Thompson, David W J

    2007-01-09

    This work surveys the depth and character of ozone depletion in the Antarctic and Arctic using available long balloon-borne and ground-based records that cover multiple decades from ground-based sites. Such data reveal changes in the range of ozone values including the extremes observed as polar air passes over the stations. Antarctic ozone observations reveal widespread and massive local depletion in the heart of the ozone "hole" region near 18 km, frequently exceeding 90%. Although some ozone losses are apparent in the Arctic during particular years, the depth of the ozone losses in the Arctic are considerably smaller, and their occurrence is far less frequent. Many Antarctic total integrated column ozone observations in spring since approximately the 1980s show values considerably below those ever observed in earlier decades. For the Arctic, there is evidence of some spring season depletion of total ozone at particular stations, but the changes are much less pronounced compared with the range of past data. Thus, the observations demonstrate that the widespread and deep ozone depletion that characterizes the Antarctic ozone hole is a unique feature on the planet.

  17. Nitrous Oxide In The Antarctic Stratosphere

    NASA Technical Reports Server (NTRS)

    Podolske, J. R.; Loewenstein, M.; Strahan, S. E.; Chan, K. R.

    1991-01-01

    Paper reports on measurements of nitrous oxide (N2O) in upper atmosphere of Southern Hemisphere, made by tunable-laser absorption spectrometer on airplane. Measurements fill gap in information about distribution of N2O over Antarctic while ozone hole forming.

  18. Antarctic Tephra Database (AntT)

    NASA Astrophysics Data System (ADS)

    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.

  19. Antarctic Peninsula Tidewater Glacier Dynamics

    NASA Astrophysics Data System (ADS)

    Pettit, E. C.; Scambos, T. A.; Haran, T. M.; Wellner, J. S.; Domack, E. W.; Vernet, M.

    2015-12-01

    The northern Antarctic Peninsula (nAP, north of 66°S) is a north-south trending mountain range extending transverse across the prevailing westerly winds of the Southern Ocean resulting in an extreme west-to-east precipitation gradient. Snowfall on the west side of the AP is one to two orders of magnitude higher than the east side. This gradient drives short, steep, fast-flowing glaciers into narrow fjords on the west side, while longer lower-sloping glaciers flow down the east side into broader fjord valleys. This pattern in ice dynamics affects ice-ocean interaction on timescales of decades to centuries, and shapes the subglacial topography and submarine bathymetry on timescales of glacial cycles. In our study, we calculate ice flux for the western and eastern nAP using a drainage model that incorporates the modern ice surface topography, the RACMO-2 precipitation estimate, and recent estimates of ice thinning. Our results, coupled with observed rates of ice velocity from InSAR (I. Joughin, personal communication) and Landsat 8 -derived flow rates (this study), provide an estimate of ice thickness and fjord depth in grounded-ice areas for the largest outlet glaciers. East-side glaciers either still terminate in or have recently terminated in ice shelves. Sedimentary evidence from the inner fjords of the western glaciers indicates they had ice shelves during LIA time, and may still have transient floating ice tongues (tabular berg calvings are observed). Although direct oceanographic evidence is limited, the high accumulation rate and rapid ice flux implies cold basal ice for the western nAP glaciers and therefore weak subglacial discharge relative to eastern nAP glaciers and or other tidewater fjord systems such as in Alaska. Finally, despite lower accumulation rates on the east side, the large elongate drainage basins result in a greater ice flux funneled through fewer deeper glaciers. Due to the relation between ice flux and erosion, these east-side glaciers

  20. Separate Origins of Ice-Binding Proteins in Antarctic Chlamydomonas Species

    PubMed Central

    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. PMID:23536869

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

    PubMed

    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.

  2. Kordia antarctica sp. nov., isolated from Antarctic seawater.

    PubMed

    Baek, Kiwoon; Choi, Ahyoung; Kang, Ilnam; Lee, Kiyoung; Cho, Jang-Cheon

    2013-10-01

    A Gram-staining-negative, chemoheterotrophic, yellow-pigmented, non-motile, flexirubin-negative, facultatively anaerobic bacterium, designated strain IMCC3317(T), was isolated from a coastal seawater sample from the Antarctic Penninsula. Optimal growth of strain IMCC3317(T) was observed at 20 °C, pH 8.0 and in the presence of 2-3 % NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain IMCC3317(T) belonged to the genus Kordia and was closely related to Kordia algicida OT-1(T) (96.7 % sequence similarity) and Kordia periserrulae IMCC1412(T) (96.1 % sequence similarity). The major fatty acids were 10-methyl C16 : 0 and/or iso-C16 : 1ω9c, iso-C17 : 0 3-OH, iso-C15 : 0 and anteiso-C15 : 0. The G+C content of the genomic DNA was 35.1 mol%. The strain contained menaquinone-6 (MK-6) as the respiratory quinone. The polar lipids detected in the strain were phosphatidylethanolamine and unknown aminophospholipids, aminolipids and polar lipids. On the basis of phylogenetic distinction and differential phenotypic characteristics, it is suggested that strain IMCC3317(T) ( = KCTC 32292(T) = NBRC 109401(T)) be assigned to the genus Kordia as the type strain of a novel species, for which the name Kordia antarctica sp. nov. is proposed.

  3. The Antarctic Master Directory -- the Electronic Card Catalog of Antarctic Data

    NASA Astrophysics Data System (ADS)

    Scharfen, G.; Bauer, R.

    2003-12-01

    The Antarctic Master Directory (AMD) is a Web-based, searchable record of thousands of Antarctic data descriptions. These data descriptions contain information about what data were collected, where they were collected, when they were collected, who the scientists are, who the point of contact is, how to get the data, and information about the format of the data and what documentation and bibliographic information exists. With this basic descriptive information about content and access for thousands of Antarctic scientific data sets, the AMD is a resource for scientists to advertise the data they have collected and to search for data they need. The AMD has been created by more than twenty nations which conduct research in the Antarctic under the auspices of the Antarctic Treaty. It is a part of the International Directory Network/Global Change Master Directory (IDN/GCMD). Using the AMD is easy. Users can search on subject matter key words, data types, geographic place-names, temporal or spatial ranges, or conduct free-text searches. To search the AMD go to: http://gcmd.nasa.gov/Data/portals/amd/. Contributing your own data descriptions for Antarctic data that you have collected is also easy. Scientists can start by submitting a short data description first (as a placeholder in the AMD, and to satisfy National Science Foundation (NSF) reporting requirements), and then add to, modify or update their record whenever it is appropriate. An easy to use on-line tool and a simple tutorial are available at: http://nsidc.org/usadcc. With NSF Office of Polar Programs (OPP) funding, the National Snow and Ice Data Center (NSIDC) operates the U.S. Antarctic Data Coordination Center (USADCC), partly to assist scientists in using and contributing to the AMD. The USADCC website is at http://nsidc.org/usadcc.

  4. Characterization of a sodium dodecyl sulphate-degrading Pseudomonas sp. strain DRY15 from Antarctic soil.

    PubMed

    Halmi, M I E; Hussin, W S W; Aqlima, A; Syed, M A; Ruberto, L; MacCormack, W P; Shukor, M Y

    2013-11-01

    A bacterium capable of biodegrading surfactant sodium dodecyl sulphate (SDS) was isolated from Antarctic soil. The isolate was tentatively identified as Pseudomonas sp. strain DRY15 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny. Growth characteristic studies showed that the bacterium grew optimally at 10 degrees C, 7.25 pH, 1 g l(-1) SDS as a sole carbon source and 2 g l(-1) ammonium sulphate as nitrogen source. Growth was completely inhibited at 5 g l(-1) SDS. At a tolerable initial concentration of 2 g l(-1), approximately 90% of SDS was degraded after an incubation period of eight days. The best growth kinetic model to fit experimental data was the Haldane model of substrate inhibition with a correlation coefficient value of 0.97. The maximum growth rate was 0.372 hr(-1) while the saturation constant or half velocity constant (Ks) and inhibition constant (Ki), were 0.094% and 11.212 % SDS, respectively. Other detergent tested as carbon sources at 1 g l(-1) was Tergitol NP9, Tergitol 15S9, Witconol 2301 (methyl oleate), sodium dodecylbenzene sulfonate (SDBS), benzethonium chloride, and benzalkonium chloride showed Tergitol NP9, Tergitol 15S9, Witconol 2301 and the anionic SDBS supported growth with the highest growth exhibited by SDBS.

  5. Novel Waddlia Intracellular Bacterium in Artibeus intermedius Fruit Bats, Mexico

    PubMed Central

    Pierlé, Sebastián Aguilar; Morales, Cirani Obregón; Martínez, Leonardo Perea; Ceballos, Nidia Aréchiga; Rivero, Juan José Pérez; Díaz, Osvaldo López; Brayton, Kelly A.

    2015-01-01

    An intracellular bacterium was isolated from fruit bats (Artibeus intermedius) in Cocoyoc, Mexico. The bacterium caused severe lesions in the lungs and spleens of bats and intracytoplasmic vacuoles in cell cultures. Sequence analyses showed it is related to Waddlia spp. (order Chlamydiales). We propose to call this bacterium Waddlia cocoyoc. PMID:26583968

  6. Marine pelagic ecosystems: the west Antarctic Peninsula.

    PubMed

    Ducklow, Hugh W; Baker, Karen; Martinson, Douglas G; Quetin, Langdon B; Ross, Robin M; Smith, Raymond C; Stammerjohn, Sharon E; Vernet, Maria; Fraser, William

    2007-01-29

    The marine ecosystem of the West Antarctic Peninsula (WAP) extends from the Bellingshausen Sea to the northern tip of the peninsula and from the mostly glaciated coast across the continental shelf to the shelf break in the west. The glacially sculpted coastline along the peninsula is highly convoluted and characterized by deep embayments that are often interconnected by channels that facilitate transport of heat and nutrients into the shelf domain. The ecosystem is divided into three subregions, the continental slope, shelf and coastal regions, each with unique ocean dynamics, water mass and biological distributions. The WAP shelf lies within the Antarctic Sea Ice Zone (SIZ) and like other SIZs, the WAP system is very productive, supporting large stocks of marine mammals, birds and the Antarctic krill, Euphausia superba. Ecosystem dynamics is dominated by the seasonal and interannual variation in sea ice extent and retreat. The Antarctic Peninsula is one among the most rapidly warming regions on Earth, having experienced a 2 degrees C increase in the annual mean temperature and a 6 degrees C rise in the mean winter temperature since 1950. Delivery of heat from the Antarctic Circumpolar Current has increased significantly in the past decade, sufficient to drive to a 0.6 degrees C warming of the upper 300 m of shelf water. In the past 50 years and continuing in the twenty-first century, the warm, moist maritime climate of the northern WAP has been migrating south, displacing the once dominant cold, dry continental Antarctic climate and causing multi-level responses in the marine ecosystem. Ecosystem responses to the regional warming include increased heat transport, decreased sea ice extent and duration, local declines in icedependent Adélie penguins, increase in ice-tolerant gentoo and chinstrap penguins, alterations in phytoplankton and zooplankton community composition and changes in krill recruitment, abundance and availability to predators. The climate

  7. Marine pelagic ecosystems: the West Antarctic Peninsula

    PubMed Central

    Ducklow, Hugh W; Baker, Karen; Martinson, Douglas G; Quetin, Langdon B; Ross, Robin M; Smith, Raymond C; Stammerjohn, Sharon E; Vernet, Maria; Fraser, William

    2006-01-01

    The marine ecosystem of the West Antarctic Peninsula (WAP) extends from the Bellingshausen Sea to the northern tip of the peninsula and from the mostly glaciated coast across the continental shelf to the shelf break in the west. The glacially sculpted coastline along the peninsula is highly convoluted and characterized by deep embayments that are often interconnected by channels that facilitate transport of heat and nutrients into the shelf domain. The ecosystem is divided into three subregions, the continental slope, shelf and coastal regions, each with unique ocean dynamics, water mass and biological distributions. The WAP shelf lies within the Antarctic Sea Ice Zone (SIZ) and like other SIZs, the WAP system is very productive, supporting large stocks of marine mammals, birds and the Antarctic krill, Euphausia superba. Ecosystem dynamics is dominated by the seasonal and interannual variation in sea ice extent and retreat. The Antarctic Peninsula is one among the most rapidly warming regions on Earth, having experienced a 2°C increase in the annual mean temperature and a 6°C rise in the mean winter temperature since 1950. Delivery of heat from the Antarctic Circumpolar Current has increased significantly in the past decade, sufficient to drive to a 0.6°C warming of the upper 300 m of shelf water. In the past 50 years and continuing in the twenty-first century, the warm, moist maritime climate of the northern WAP has been migrating south, displacing the once dominant cold, dry continental Antarctic climate and causing multi-level responses in the marine ecosystem. Ecosystem responses to the regional warming include increased heat transport, decreased sea ice extent and duration, local declines in ice-dependent Adélie penguins, increase in ice-tolerant gentoo and chinstrap penguins, alterations in phytoplankton and zooplankton community composition and changes in krill recruitment, abundance and availability to predators. The climate/ecological gradients

  8. Emerging spatial patterns in Antarctic prokaryotes

    PubMed Central

    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

  9. Chemical studies of H chondrites. 6: Antarctic/non-Antarctic compositional differences revisited

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen F.; Lipschutz, Michael E.

    1995-01-01

    We report data for the trace elements Au, Co, Sb, Ga, Rb, Ag, Se, Cs, Te, Zn, Cd, Bi, T1, and In (ordered by putative volatility during nebular condensation and accretion) determined by radiochemical neutron activation analysis of 14 additional H5 and H6 chondrite falls. Data for the 10 most volatile elements (Rb to In) treated by the multivariate techniques of linear discriminant analysis and logistic regression in these and 44 other falls are compared with those of 59 H4-6 chondrites from Antarctica. Various populations are tested by the multivariate techniques, using the previously developed method of randomization-simulation to assess significance levels. An earlier conclusion, based on fewer examples, that H4-6 chondrite falls are compositionally distinguishable from the Antarctic suite is verified by the additional data. This distinctiveness is highly significant because of the presence of samples from Victoria Land in the Antarctic population, which differ compositionally from falls beyond any reasonable doubt. However, it cannot be proven unequivocally that falls and Antarctic samples from Queen Maud Land are compositionally distinguishable. Trivial causes (e.g., analyst bias, weathering) cannot explain the Victoria Land (Antarctic)/non-Antarctic compositional difference for paradigmatic H4-6 chondrites. This seems to reflect a time-dependent variation of near-Earth meteoroid source regions differing in average thermal history.

  10. Degradation of lambda-carrageenan by Pseudoalteromonas carrageenovora lambda-carrageenase: a new family of glycoside hydrolases unrelated to kappa- and iota-carrageenases.

    PubMed

    Guibet, Marion; Colin, Sébastien; Barbeyron, Tristan; Genicot, Sabine; Kloareg, Bernard; Michel, Gurvan; Helbert, William

    2007-05-15

    Carrageenans are sulfated galactans found in the cell walls of red seaweeds. They are classified according to the number and the position of sulfate ester groups. lambda-Carrageenan is the most sulfated carrageenan and carries at least three sulfates per disaccharide unit. The sole known depolymerizing enzyme of lambda-carrageenan, the lambda-carrageenase from Pseudoalteromonas carrageenovora, has been purified, cloned and sequenced. Sequence analyses have revealed that the lambda-carrageenase, referred to as CglA, is the first member of a new family of GHs (glycoside hydrolases), which is unrelated to families GH16, that contains kappa-carrageenases, and GH82, that contains iota-carrageenases. This large enzyme (105 kDa) features a low-complexity region, suggesting the presence of a linker connecting at least two independent modules. The N-terminal region is predicted to fold as a beta-propeller. The main degradation products have been purified and characterized as neo-lambda-carratetraose [DP (degree of polymerization) 4] and neo-lambda-carrahexaose (DP6), indicating that CglA hydrolyses the beta-(1-->4) linkage of lambda-carrageenan. LC-MALLS (liquid chromatography-multi-angle laser light scattering) and (1)H-NMR monitoring of the enzymatic degradation of lambda-carrageenan indicate that CglA proceeds according to an endolytic mode of action and a mechanism of inversion of the anomeric configuration. Using 2-aminoacridone-labelled neo-lambda-carrabiose oligosaccharides, in the present study we demonstrate that the active site of CglA comprises at least 8 subsites (-4 to +4) and that a DP6 oligosaccharide binds in the subsites -4 to +2 and can be hydrolysed into DP4 and DP2.

  11. Characterization of a New Cold-Adapted and Salt-Activated Polysaccharide Lyase Family 7 Alginate Lyase from Pseudoalteromonas sp. SM0524

    PubMed Central

    Chen, Xiu-Lan; Dong, Sheng; Xu, Fei; Dong, Fang; Li, Ping-Yi; Zhang, Xi-Ying; Zhou, Bai-Cheng; Zhang, Yu-Zhong; Xie, Bin-Bin

    2016-01-01

    Marine bacterial alginate lyases play a role in marine alginate degradation and carbon cycling. Although a large number of alginate lyases have been characterized, reports on alginate lyases with special characteristics are still rather less. Here, a gene alyPM encoding an alginate lyase of polysaccharide lyase family 7 (PL7) was cloned from marine Pseudoalteromonas sp. SM0524 and expressed in Escherichia coli. AlyPM shows 41% sequence identity to characterized alginate lyases, indicating that AlyPM is a new PL7 enzyme. The optimal pH for AlyPM activity was 8.5. AlyPM showed the highest activity at 30°C and remained 19% of the highest activity at 5°C. AlyPM was unstable at temperatures above 30°C and had a low Tm of 37°C. These data indicate that AlyPM is a cold-adapted enzyme. Moreover, AlyPM is a salt-activated enzyme. AlyPM activity in 0.5–1.2 M NaCl was sixfolds higher than that in 0 M NaCl, probably caused by a significant increase in substrate affinity, because the Km of AlyPM in 0.5 M NaCl decreased more than 20-folds than that in 0 M NaCl. AlyPM preferably degraded polymannuronate and mainly released dimers and trimers. These data indicate that AlyPM is a new PL7 endo-alginate lyase with special characteristics. PMID:27486451

  12. The signs of Antarctic ozone hole recovery.

    PubMed

    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.

  13. Subsurface Salts in Antarctic Dry Valley Soils

    NASA Technical Reports Server (NTRS)

    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.

  14. The history of Antarctic Peninsula glaciation

    USGS Publications Warehouse

    Barker, Peter F.

    2007-01-01

    As Co-Chief Scientist on DSDP Leg 35 in 1974, Cam Craddock (1930-2006) produced the first useful information on Cenozoic Antarctic Peninsula glaciation - an early middle Miocene (15-17 Ma) apparent glacial onset. Subsequent work, onshore and offshore, has greatly extended our knowledge but that early conclusion stands today. Cenozoic Antarctic Peninsula palaeoclimate as presently known is broadly consistent with global palaeoclimate proxies. Initial glacial onset was within the Eocene-Oligocene boundary interval (although earlier, short-lived glaciations have been proposed, from indirect measurements) and the peninsula probably became deglaciated in the earliest Miocene (ca. 24 Ma). The renewed middle Miocene glaciation probably continued to the present and, for the last 9 Myr at least, has persisted through glacial (orbital) cycles, with grounded ice advance to the shelf edge during maxima. Although orbital cyclicity affected earlier AP palaeoclimate also, the level of glaciation through a complete cycle is uncertain.

  15. Antarctic Meteorite Classification and Petrographic Database

    NASA Technical Reports Server (NTRS)

    Todd, Nancy S.; Satterwhite, C. E.; Righter, Kevin

    2011-01-01

    The Antarctic Meteorite collection, which is comprised of over 18,700 meteorites, is one of the largest collections of meteorites in the world. These meteorites have been collected since the late 1970's as part of a three-agency agreement between NASA, the National Science Foundation, and the Smithsonian Institution [1]. Samples collected each season are analyzed at NASA s Meteorite Lab and the Smithsonian Institution and results are published twice a year in the Antarctic Meteorite Newsletter, which has been in publication since 1978. Each newsletter lists the samples collected and processed and provides more in-depth details on selected samples of importance to the scientific community. Data about these meteorites is also published on the NASA Curation website [2] and made available through the Meteorite Classification Database allowing scientists to search by a variety of parameters

  16. A simulated Antarctic fast ice ecosystem

    NASA Technical Reports Server (NTRS)

    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.

  17. Meteoritic event recorded in Antarctic ice

    SciTech Connect

    Harvey, R.P.; Dunbar, N.W.; McIntosh, W.C.; Esser, R.P.; Nishiizumi, Kuni; Taylor, S.; Caffee, M.W.

    1998-07-01

    During systematic sampling of volcanic ash (tephra) layers at a well-known Antarctic meteorite collection site (the Allan Hills main ice field), a band of unusually dark and rounded (many spheroidal) particles was discovered. This debris layer (BIT-58) extends parallel to the stratigraphy of the ice established from the tephra bands, apparently marking a single depositional event. The shapes, internal texture, major element composition, and levels of cosmogenic nuclides of particles from within BIT-58 all strongly suggest that this material represents ablation debris from the passage of a large H-group ordinary chondrite. Preliminary cosmogenic isotope dating suggests an age of 2.8 Ma, implying that the East Antarctic ice sheet has been stable since that time. The relationship of the Bit-58 layer to known impact events is not clear.

  18. Total Mercury in Six Antarctic Notothenioid Fishes.

    PubMed

    Wintle, Nathan J P; Sleadd, Isaac M; Gundersen, Deke T; Kohl, Kristina; Buckley, Bradley A

    2015-11-01

    We analyzed white muscle samples from six species of Antarctic fish (suborder Notothenioidei) collected in 2011 from McMurdo Sound, Ross Sea, Antarctica, to assess levels of total mercury (THg). Gymnodraco acuticeps and Trematomus bernacchii exhibited the highest concentrations of THg followed by Trematomus pennellii, Trematomus nicolai, Trematomus newnesi and Pagothenia borchgrevinki, (71.3, 53.9±32.1, 45.8±27.3, 37.2±18.6, 35.7±23.6, and 21.9±2.8 ng/g wet weight, respectively). The results from this study suggest that THg has the potential to bioaccumulate from various marine Antarctic ecosystems into biota.

  19. A simulated Antarctic fast ice ecosystem

    NASA Technical Reports Server (NTRS)

    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.

  20. Antarctic microfungi as models for exobiology

    NASA Astrophysics Data System (ADS)

    Onofri, S.; Selbmann, L.; Zucconi, L.; Pagano, S.

    2004-01-01

    Microfungi living in different Antarctic environments are generally well adapted to high stress conditions such as low temperatures, wide thermal fluctuations, high UV irradiance, and low water and nutrients availability; for this reason they could be investigated in order to explore limits of microbial life. Microfungi living in simple cryptoendolithic microbial communities inside the porosity of rocks in the Antarctic Dry Valleys, the closest terrestrial analogue of Mars, are particularly suitable for exobiological studies. Until now studies on exobiology focused mainly on prokaryotes; since cryptoendolithic black meristematic fungi are able to tolerate hard desiccation, high UV exposure, extremely low temperatures and wide thermal fluctuations, they are proposed as the best eukaryotic models for the biological exploration of Mars. Indeed, their adaptive strategies could be crucial as predictive tools in investigating the limits of life.

  1. Structural Uncertainty in Antarctic sea ice simulations

    NASA Astrophysics Data System (ADS)

    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

  2. Freezing resistance in some Antarctic fishes.

    PubMed

    DeVries, A L; Wohlschlag, D E

    1969-03-07

    Measurements of serum freezing points in three Antarctic marine fishes indicated that they do not freeze in the -1.87 degrees C seawater because their blood is isosmotic to seawater. Concentrations of sodium chloride, urea, and free amino acids in the serum accounted for only half of the freezing-point depression of the serum. A protein containing carbohydrate was isolated which accounted for 30 percent of the freezing-point depression of the serum.

  3. Evolution of the early Antarctic ice ages

    NASA Astrophysics Data System (ADS)

    Liebrand, Diederik; de Bakker, Anouk T. M.; Beddow, Helen M.; Wilson, Paul A.; Bohaty, Steven M.; Ruessink, Gerben; Pälike, Heiko; Batenburg, Sietske J.; Hilgen, Frederik J.; Hodell, David A.; Huck, Claire E.; Kroon, Dick; Raffi, Isabella; Saes, Mischa J. M.; van Dijk, Arnold E.; Lourens, Lucas J.

    2017-04-01

    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 deep-sea oxygen isotope (δ18O) record from the South Atlantic Ocean spanning an interval between 30.1 My and 17.1 My ago. The record displays major oscillations in deep-sea temperature and Antarctic ice volume in response to the ˜110-ky eccentricity modulation of precession. Conservative minimum ice volume estimates show that waxing and waning of at least ˜85 to 110% of the volume of the present East Antarctic Ice Sheet is required to explain many of the ˜110-ky cycles. Antarctic ice sheets were typically largest during repeated glacial cycles of the mid-Oligocene (˜28.0 My to ˜26.3 My ago) and across the Oligocene-Miocene Transition (˜23.0 My ago). However, the high-amplitude glacial-interglacial cycles of the mid-Oligocene are highly symmetrical, indicating a more direct response to eccentricity modulation of precession than their Early Miocene counterparts, which are distinctly asymmetrical—indicative of prolonged ice buildup and delayed, but rapid, glacial terminations. We hypothesize that the long-term transition to a warmer climate state with sawtooth-shaped glacial cycles in the Early Miocene was brought about by subsidence and glacial erosion in West Antarctica during the Late Oligocene and/or a change in the variability of atmospheric CO2 levels on astronomical time scales that is not yet captured in existing proxy reconstructions.

  4. Evolution of the early Antarctic ice ages

    PubMed Central

    de Bakker, Anouk T. M.; Beddow, Helen M.; Wilson, Paul A.; Bohaty, Steven M.; Pälike, Heiko; Batenburg, Sietske J.; Hilgen, Frederik J.; Hodell, David A.; Huck, Claire E.; Kroon, Dick; Raffi, Isabella; Saes, Mischa J. M.; van Dijk, Arnold E.; Lourens, Lucas J.

    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 deep-sea oxygen isotope (δ18O) record from the South Atlantic Ocean spanning an interval between 30.1 My and 17.1 My ago. The record displays major oscillations in deep-sea temperature and Antarctic ice volume in response to the ∼110-ky eccentricity modulation of precession. Conservative minimum ice volume estimates show that waxing and waning of at least ∼85 to 110% of the volume of the present East Antarctic Ice Sheet is required to explain many of the ∼110-ky cycles. Antarctic ice sheets were typically largest during repeated glacial cycles of the mid-Oligocene (∼28.0 My to ∼26.3 My ago) and across the Oligocene−Miocene Transition (∼23.0 My ago). However, the high-amplitude glacial−interglacial cycles of the mid-Oligocene are highly symmetrical, indicating a more direct response to eccentricity modulation of precession than their Early Miocene counterparts, which are distinctly asymmetrical—indicative of prolonged ice buildup and delayed, but rapid, glacial terminations. We hypothesize that the long-term transition to a warmer climate state with sawtooth-shaped glacial cycles in the Early Miocene was brought about by subsidence and glacial erosion in West Antarctica during the Late Oligocene and/or a change in the variability of atmospheric CO2 levels on astronomical time scales that is not yet captured in existing proxy reconstructions. PMID:28348211

  5. Evolution of the early Antarctic ice ages.

    PubMed

    Liebrand, Diederik; de Bakker, Anouk T M; Beddow, Helen M; Wilson, Paul A; Bohaty, Steven M; Ruessink, Gerben; Pälike, Heiko; Batenburg, Sietske J; Hilgen, Frederik J; Hodell, David A; Huck, Claire E; Kroon, Dick; Raffi, Isabella; Saes, Mischa J M; van Dijk, Arnold E; Lourens, Lucas J

    2017-04-11

    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 deep-sea oxygen isotope (δ(18)O) record from the South Atlantic Ocean spanning an interval between 30.1 My and 17.1 My ago. The record displays major oscillations in deep-sea temperature and Antarctic ice volume in response to the ∼110-ky eccentricity modulation of precession. Conservative minimum ice volume estimates show that waxing and waning of at least ∼85 to 110% of the volume of the present East Antarctic Ice Sheet is required to explain many of the ∼110-ky cycles. Antarctic ice sheets were typically largest during repeated glacial cycles of the mid-Oligocene (∼28.0 My to ∼26.3 My ago) and across the Oligocene-Miocene Transition (∼23.0 My ago). However, the high-amplitude glacial-interglacial cycles of the mid-Oligocene are highly symmetrical, indicating a more direct response to eccentricity modulation of precession than their Early Miocene counterparts, which are distinctly asymmetrical-indicative of prolonged ice buildup and delayed, but rapid, glacial terminations. We hypothesize that the long-term transition to a warmer climate state with sawtooth-shaped glacial cycles in the Early Miocene was brought about by subsidence and glacial erosion in West Antarctica during the Late Oligocene and/or a change in the variability of atmospheric CO2 levels on astronomical time scales that is not yet captured in existing proxy reconstructions.

  6. Antarctic Ice Charts, 1987-1988

    DTIC Science & Technology

    1988-01-01

    U.S. Navy has a long and eventful history of polar exploration from Robert E. Peary in the Arctic to Richard E. Byrd in the Antarctic. In recent...environmental information. Since 1976, the National Oceanic and Atmospheric Administration (NOAA) and the Navy have worked together at the Joint Ice Center...to provide the user with reliable weekly hemispheric ice analyses. Both Navy and NOAA personnel with considerable experience in sea ice analysis

  7. America on the Ice. Antarctic Policy Issues

    DTIC Science & Technology

    1990-01-01

    South Pole Station 166 McMurdo Station . logistics hub of US Antarctic program 170 Amundsen - Scott Station establishes US presence 172 Paul Siple. American...additi onal stations . inc I tding, the Amundsen - Scott station at the South Pole , %kere conm- pleted.1t While the polar site \\\\as important for tdin...porarily, there-Roald Amundsen and Robert Falcon SCott . The United States first built a station at the

  8. A diagnostic study of Antarctic fog

    NASA Astrophysics Data System (ADS)

    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.

  9. Adaptive-optics performance of Antarctic telescopes.

    PubMed

    Lawrence, Jon S

    2004-02-20

    The performance of natural guide star adaptive-optics systems for telescopes located on the Antarctic plateau is evaluated and compared with adaptive-optics systems operated with the characteristic mid-latitude atmosphere found at Mauna Kea. A 2-m telescope with tip-tilt correction and an 8-m telescope equipped with a high-order adaptive-optics system are considered. Because of the large isoplanatic angle of the South Pole atmosphere, the anisoplanatic error associated with an adaptive-optics correction is negligible, and the achievable resolution is determined only by the fitting error associated with the number of corrected wave-front modes, which depends on the number of actuators on the deformable mirror. The usable field of view of an adaptive-optics equipped Antarctic telescope is thus orders of magnitude larger than for a similar telescope located at a mid-latitude site; this large field of view obviates the necessity for multiconjugate adaptive-optics systems that use multiple laser guide stars. These results, combined with the low infrared sky backgrounds, indicate that the Antarctic plateau is the best site on Earth at which to perform high-resolution imaging with large telescopes, either over large fields of view or with appreciable sky coverage. Preliminary site-testing results obtained recently from the Dome Concordia station indicate that this site is far superior to even the South Pole.

  10. Balance of the West Antarctic Ice Sheet

    NASA Technical Reports Server (NTRS)

    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

  11. Bacteria beneath the West Antarctic ice sheet.

    PubMed

    Lanoil, Brian; Skidmore, Mark; Priscu, John C; Han, Sukkyun; Foo, Wilson; Vogel, Stefan W; Tulaczyk, Slawek; Engelhardt, Hermann

    2009-03-01

    Subglacial environments, particularly those that lie beneath polar ice sheets, are beginning to be recognized as an important part of Earth's biosphere. However, except for indirect indications of microbial assemblages in subglacial Lake Vostok, Antarctica, no sub-ice sheet environments have been shown to support microbial ecosystems. Here we report 16S rRNA gene and isolate diversity in sediments collected from beneath the Kamb Ice Stream, West Antarctic Ice Sheet and stored for 15 months at 4 degrees C. This is the first report of microbes in samples from the sediment environment beneath the Antarctic Ice Sheet. The cells were abundant ( approximately 10(7) cells g(-1)) but displayed low diversity (only five phylotypes), likely as a result of enrichment during storage. Isolates were cold tolerant and the 16S rRNA gene diversity was a simplified version of that found in subglacial alpine and Arctic sediments and water. Although in situ cell abundance and the extent of wet sediments beneath the Antarctic ice sheet can only be roughly extrapolated on the basis of this sample, it is clear that the subglacial ecosystem contains a significant and previously unrecognized pool of microbial cells and associated organic carbon that could potentially have significant implications for global geochemical processes.

  12. Antarctic Meteorite Classification and Petrographic Database Enhancements

    NASA Technical Reports Server (NTRS)

    Todd, N. S.; Satterwhite, C. E.; Righter, K.

    2012-01-01

    The Antarctic Meteorite collection, which is comprised of over 18,700 meteorites, is one of the largest collections of meteorites in the world. These meteorites have been collected since the late 1970 s as part of a three-agency agreement between NASA, the National Science Foundation, and the Smithsonian Institution [1]. Samples collected each season are analyzed at NASA s Meteorite Lab and the Smithsonian Institution and results are published twice a year in the Antarctic Meteorite Newsletter, which has been in publication since 1978. Each newsletter lists the samples collected and processed and provides more in-depth details on selected samples of importance to the scientific community. Data about these meteorites is also published on the NASA Curation website [2] and made available through the Meteorite Classification Database allowing scientists to search by a variety of parameters. This paper describes enhancements that have been made to the database and to the data and photo acquisition process to provide the meteorite community with faster access to meteorite data concurrent with the publication of the Antarctic Meteorite Newsletter twice a year.

  13. Antarctic Treaty Summit: Washington, DC (2009)

    NASA Astrophysics Data System (ADS)

    Berkman, P. A.; Young, O. R.

    2005-12-01

    Advancement in Earth system science and international cooperation have been intertwined with the International Polar Years since 1882. In particular, the 3rd International Polar Year (which was convened as the International Geophysical Year from 1 July 1957 through 31 December 1958) specifically demonstrates the role of science in international policy: Acknowledging the substantial contributions to scientific knowledge resulting from international cooperation in scientific investigation in Antarctica; Convinced that the establishment of a firm foundation for the continuation and development of such cooperation on the basis of freedom of scientific investigation in Antarctica as applied during the International Geophysical Year accords with the interests of science and the progress of all mankind; Preamble, 1959 Antarctic Treaty To commemorate the 50th anniversary of the 1959 Antarctic Treaty and to explore the complexities of the science-policy relationship through the lens of a well-constrained case study, an international and interdisciplinary Antarctic Treaty Summit is being planned for 2009 in Washington, DC in conjunction with the International Polar Year 2007-08 (http://www.ipy.org).

  14. EVA: Evryscopes for the Arctic and Antarctic

    NASA Astrophysics Data System (ADS)

    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.

  15. Update on terrestrial ages of Antarctic meteorites

    SciTech Connect

    Welten, K C; Nishiizumi, K; Caffee, M W

    2000-01-14

    Terrestrial ages of Antarctic meteorites are one of the few parameters that will help us to understand the meteorite concentration mechanism on blue-ice fields. Traditionally, terrestrial ages were determined on the basis of {sup 36}Cl in the metal phase, which has an uncertainty of about 70 ky. For young meteorites (< 40 ky), the terrestrial age is usually and most accurately determined using {sup 14}C in the stone phase. In recent years two methods have been developed which are independent of shielding effects, the {sup 10}Be-{sup 36}Cl/{sup 10}Be method and the {sup 41}Ca/{sup 36}Cl method. These methods have reduced the typical uncertainties in terrestrial ages by a factor of 2, to about 30 ky. The {sup 10}Be-{sup 36}Cl/{sup 10}Be method is quite dependent on the exposure age, which is unknown for most Antarctic meteorites. The authors therefore also attempt to use the relation between {sup 26}Al and {sup 36}Cl/{sup 26}Al to derive a terrestrial age less dependent on the exposure age. The authors have measured the concentrations of cosmogenic {sup 10}Be, {sup 26}Al and {sup 36}Cl in the metal phase of {approximately} 70 Antarctic meteorites, from more than 10 different ice-fields, including many new ones. They then discuss the trends in terrestrial ages of meteorites from different ice-fields.

  16. Technology for a remote automated Antarctic observatory

    NASA Astrophysics Data System (ADS)

    Ashley, M. C. B.; Lawrence, J.; Storey, J. W. V.; Burton, M. G.; Hengst, S.; Luong-van, D.

    2006-08-01

    Encouraged by recent data from Dome C station demonstrating the unique potential of the high Antarctic plateau for astronomy, a number of international groups intend to deploy telescopes and site testing instrumentation to various unmanned locations on the Antarctic plateau within the next few years. These instruments will require a reliable completely autonomous observatory to provide power, heat, control, and communications throughout the Antarctic winter. The AASTINO (Automated Astrophysical Site Testing International Observatory), which was designed with these goals, was deployed to Dome C in January 2003. It has successfully demonstrated many of the concepts essential for such operation. The second generation AASTINO, currently in development, has an extremely flexible power generation system that can consist of solar, battery, diesel, and stirling cycle systems. Power and Control Area Network (CAN) data is available to all scientific instruments via a universal connector system, simplifying the integration of instruments developed by diverse research teams and ensuring a more straightforward deployment process. System monitoring, commands, and low bandwidth experimental data transfer, is performed via a redundant Iridium satellite network up-link. Bulk data storage is achieved via a redundant array of mechanical hard disk drives in an atmospherically modified enclosure, preventing damage by low pressure and temperature. A dual redundant supervisor system controls all aspects of communication and control, and can handle individual system failures as well as many catastrophic computer failures. In the event of total communication loss, the supervisor system is designed to control all experiments autonomously including the rationing of electrical power.

  17. Antarctic isolation: immune and viral studies

    NASA Technical Reports Server (NTRS)

    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.

  18. Antarctic isolation: immune and viral studies

    NASA Technical Reports Server (NTRS)

    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.

  19. A paleomagnetic study of the Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Poblete, F.; Arriagada, C.; Roperch, P.

    2009-05-01

    In the Paleozoic, South America, South Africa and Antarctica were part of Gondwana. The Weddell Sea began to form at about 146 Ma, after rifting between the Antarctic Peninsula and southernmost South America. Much uncertainty still exists about the geometrical fit and subsequent drift history between Patagonia and Antarctica. Geophysical and geological data which describe the tectonic history are sparsely distributed and often of poor quality. During the last two years we have collected more than 1000 paleomagnetic samples from 70 sites at several localities (King George Island, Robert Island, Yankee Bay, Half Moon Island, Byers Peninsula and Snow Island) from the South Shetland Islands and Anderson Island in the northern tip of Antarctic Peninsula. Our main objective was to provide first-order constraints on latitudinal displacements and the amount of tectonic rotations as an essential test of published tectonic models. Paleomagnetic results were obtained from 50 sites. All samples from sites in volcanic and intrusive rocks have well-defined univectorial magnetizations. Unfortunately, all sites in late Paleozoic sediments have been remagnetized and the magnetizations are often unstable upon thermal demagnetization. Cretaceous and Cenozoic units display very little apparent polar wander. Results from intrusive rocks of expected Jurassic age do not confirm the expected relative rotation betwen the Antarctic Peninsula and East Antarctica. Further radiometric dating are needed to confirm the age of these units.

  20. New spiral bacterium in gastric mucosa.

    PubMed

    McNulty, C A; Dent, J C; Curry, A; Uff, J S; Ford, G A; Gear, M W; Wilkinson, S P

    1989-06-01

    A new spiral bacterium, distinct from Campylobacter pylori, was found in the gastric mucosa of six patients with gastrointestinal symptoms. All patients had chronic active type B gastritis and four had oesophagitis. Culture and microscopy for C pylori infection was negative. These unculturable spiral organisms were probably an incidental finding in patients presenting for upper gastrointestinal endoscopy, but it is not possible to say from this small series whether these organisms cause chronic active gastritis. The organism is helical, 3.5-7.5 microns long and 0.9 micron in diameter with truncated ends flattened at the tips, and up to 12 sheathed flagella 28 nm in diameter at each pole. It is proposed that this spiral bacterium should be called "Gastrospirillum hominis Gen.nov., Sp.nov."

  1. New spiral bacterium in gastric mucosa.

    PubMed Central

    McNulty, C A; Dent, J C; Curry, A; Uff, J S; Ford, G A; Gear, M W; Wilkinson, S P

    1989-01-01

    A new spiral bacterium, distinct from Campylobacter pylori, was found in the gastric mucosa of six patients with gastrointestinal symptoms. All patients had chronic active type B gastritis and four had oesophagitis. Culture and microscopy for C pylori infection was negative. These unculturable spiral organisms were probably an incidental finding in patients presenting for upper gastrointestinal endoscopy, but it is not possible to say from this small series whether these organisms cause chronic active gastritis. The organism is helical, 3.5-7.5 microns long and 0.9 micron in diameter with truncated ends flattened at the tips, and up to 12 sheathed flagella 28 nm in diameter at each pole. It is proposed that this spiral bacterium should be called "Gastrospirillum hominis Gen.nov., Sp.nov." Images Fig 1 Fig 2 Fig 3 Fig 4 PMID:2738164

  2. Characterization of a novel extremely alkalophilic bacterium

    NASA Technical Reports Server (NTRS)

    Souza, K. A.; Deal, P. H.

    1977-01-01

    A new alkalophilic bacterium, isolated from a natural spring of high pH is characterized. It is a Gram-positive, non-sporulating, motile rod requiring aerobic and alkaline conditions for growth. The characteristics of this organism resemble those of the coryneform group of bacteria; however, there are no accepted genera within this group with which this organism can be closely matched. Therefore, a new genus may be warranted.

  3. Pneumonia caused by a previously undescribed bacterium.

    PubMed Central

    Hopfer, R L; Mills, K; Fainstein, V; Fischer, H E; Luna, M P

    1982-01-01

    A new and as yet unidentified bacterium was isolated from the lung tissue of a cancer patient with bilateral pneumonia. Clinically, the pneumonia was consistent with legionellosis; the organism cultured from the lung grew only on the charcoal-yeast extract agar routinely used for Legionella isolation. Subsequent testing, however, showed the organism to be quite distinct from the known Legionella species in its biochemical, antigenic, and growth characteristics. Images PMID:7130363

  4. Paradigms: examples from the bacterium Xylella fastidiosa.

    PubMed

    Purcell, Alexander

    2013-01-01

    The history of advances in research on Xylella fastidiosa provides excellent examples of how paradigms both advance and limit our scientific understanding of plant pathogens and the plant diseases they cause. I describe this from a personal perspective, having been directly involved with many persons who made paradigm-changing discoveries, beginning with the discovery that a bacterium, not a virus, causes Pierce's disease of grape and other plant diseases in numerous plant species, including important crop and forest species.

  5. Modelling Antarctic sea-level data to explore the possibility of a dominant Antarctic contribution to meltwater pulse IA

    NASA Astrophysics Data System (ADS)

    Bassett, S. E.; Milne, G. A.; Bentley, M. J.; Huybrechts, P.

    2007-09-01

    We compare numerical predictions of glaciation-induced sea-level change to data from 8 locations around the Antarctic coast in order to test if the available data preclude the possibility of a dominant Antarctic contribution to meltwater pulse IA (mwp-IA). Results based on a subset of 7 spherically symmetric earth viscosity models and 6 different Antarctic deglaciation histories indicate that the sea-level data do not rule out a large Antarctic source for this event. Our preliminary analysis indicates that the Weddell Sea is the most likely source region for a large (˜9 m) Antarctic contribution to mwp-IA. The Ross Sea is also plausible as a significant contributor (˜5 m) from a sea-level perspective, but glacio-geological field observations are not compatible with such a large and rapid melt from this region. Our results suggest that the Lambert Glacier component of the East Antarctic ice sheet experienced significant retreat at the time of mwp-IA, but only contributed ˜0.15 m (eustatic sea-level change). All of the ice models considered under-predicted the isostatic component of the sea-level response in the Antarctic Peninsula and the Sôya Coast region of the East Antarctic ice sheet, indicating that the maximum ice thickness in these regions is underestimated. It is therefore plausible that ice melt from these areas, the Antarctic Peninsula in particular, could have made a significant contribution to mwp-IA.

  6. Terrestrial Ages of Antarctic Meteorites- Update 1999

    NASA Technical Reports Server (NTRS)

    Nishiizumi, Kunihiko; Welten, K. C.; Caffee, Marc W.

    1999-01-01

    We are continuing our ongoing study of cosmogenic nuclides in Antarctic meteorites. In addition to the studies of exposure histories of meteorites, we study terrestrial ages and pairing of Antarctic meteorites and desert meteorites. Terrestrial ages of Antarctic meteorites provide information on meteorite accumulation mechanisms, mean weathering lifetimes, and influx rates. The determination of Cl-36(half-life=3.01 x 10(exp 5) y) terrestrial ages is one of our long-term on-going projects, however, in many instances neither Cl-36 or C-14 (5,730 y) yields an accurate terrestrial age. Using Ca-14 (1.04 x 10(exp 5) y) for terrestrial age determinations solves this problem by filling the c,ap in half-life between 14-C and Cl-36 ages. We are now applying the new Ca-41- Cl-36 terrestrial age method as well as the Cl-36-Be-10 method to Antarctic meteorites. Our measurements and C-14 terrestrial age determinations by the University of Arizona group are always complementary. We have measured Cl-36 in over 270 Antarctic meteorites since our previous compilation of terrestrial ages. Since a large number of meteorites have been recovered from many different icefields in Antarctica, we continue to survey the trends of terrestrial ages for different icefields. We have also measured detailed terrestrial ages vs. sample locations for Allan Hills, Elephant Moraine, and Lewis Cliff Icefields, where meteorites have been found with very long ages. The updated histograms of terrestrial ages of meteorites from the Allan Hills Main Icefield and Lewis Cliff Icefield are shown. These figures include C-14 ages obtained by the University of Arizona group. Pairs of meteorites are shown as one object for which the age is the average of all members of the same fall. The width of the bars represents 70,000 years, which was a typical uncertainty for Cl-36 ages. We reduced the uncertainty of terrestrial age determinations to approx. 40,000 years by using pairs of nuclides such as Ca-41-Cl-36 or Cl

  7. The ARM West Antarctic Radiation Experiment (AWARE)

    NASA Astrophysics Data System (ADS)

    Lubin, Dan; Bromwich, David; Vogelmann, Andrew; Verlinde, Johannes; Russell, Lynn

    2016-04-01

    West Antarctica is one of the most rapidly warming regions on Earth, and its changing climate in both atmosphere and ocean is linked to loss of Antarctic ice mass and global sea level rise. The specific mechanisms for West Antarctic Ice Sheet (WAIS) warming are not fully understood, but are hypothesized to involve linkage between moisture from Southern Ocean storm tracks and the surface energy balance over the WAIS, and related teleconnections with subtropical and tropical meteorology. This present lack of understanding has motivated a climate science and cloud physics campaign jointly supported by the US National Science Foundation (NSF) and Department of Energy (DOE), called the Atmospheric Radiation Measurement Program (ARM) West Antarctic Radiation Experiment (AWARE). The DOE's second ARM Mobile Facility (AMF2) was deployed to McMurdo Station on Ross Island in November 2015 and will operate through December 2016. The AMF2 includes (1) cloud research radars, both scanning and zenith, operating in the Ka- and X-bands, (2) high spectral resolution and polarized micropulse lidars, and (3) a suite of shortwave and longwave broadband and spectral radiometers. A second suite of instruments is deployed at the WAIS Divide Ice Camp on the West Antarctic plateau during December 2015 and January 2016. The WAIS instrument suite provides (1) measurement of all surface energy balance components, (2) a polarized micropulse lidar and shortwave spectroradiometer, (3) microwave total water column measurement, and (4) four times daily rawinsonde launches which are the first from West Antarctica since 1967. There is a direct linkage between the WAIS instrument suite and the AMF2 at McMurdo, in that air masses originating in Southern Ocean storm tracks that are driven up over the WAIS often subsequently descend over the Ross Ice Shelf and arrive at Ross Island. Preliminary data are already illustrating the prevalence of mixed-phase clouds and their role in the surface energy balance

  8. Unveiling the pan-genome of the SXT/R391 family of ICEs: molecular characterisation of new variable regions of SXT/R391-like ICEs detected in Pseudoalteromonas sp. and Vibrio scophthalmi.

    PubMed

    Rodríguez-Blanco, Arturo; Lemos, Manuel L; Osorio, Carlos R

    2016-08-01

    Integrating conjugative elements (ICEs) of the SXT/R391 family have been identified in fish-isolated bacterial strains collected from marine aquaculture environments of the northwestern Iberian Peninsula. Here we analysed the variable regions of two ICEs, one preliminarily characterised in a previous study (ICEVscSpa3) and one newly identified (ICEPspSpa1). Bacterial strains harboring these ICEs were phylogenetically assigned to Vibrio scophthalmi and Pseudoalteromonas sp., thus constituting the first evidence of SXT/R391-like ICEs in the genus Pseudoalteromonas to date. Variable DNA regions, which confer element-specific properties to ICEs of this family, were characterised. Interestingly, the two ICEs contained 29 genes not found in variable DNA insertions of previously described ICEs. Most notably, variable gene content for ICEVscSpa3 showed similarity to genes potentially involved in housekeeping functions of replication, nucleotide metabolism and transcription. For these genes, closest homologues were found clustered in the genome of Pseudomonas psychrotolerans L19, suggesting a transfer as a block to ICEVscSpa3. Genes encoding antibiotic resistance, restriction modification systems and toxin/antitoxin systems were absent from hotspots of ICEVscSpa3. In contrast, the variable gene content of ICEPspSpa1 included genes involved in restriction/modification functions in two different hotspots and genes related to ICE maintenance. The present study unveils a relatively large number of novel genes in SXT/R391-ICEs, and demonstrates the major role of ICE elements as contributors to horizontal gene transfer.

  9. Geoethical Approach to Antarctic Subglacial Lakes Exploration

    NASA Astrophysics Data System (ADS)

    Talalay, Pavel; Markov, Alexey; Sysoev, Mikhail

    2014-05-01

    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 anticipated direct access down to the lakes Ellsworth and Whillans, respectively, in the 2012/2013 Antarctic season. A team of British scientists and engineers engaged 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. Hot water is considered by the world science community as the most clean drilling fluid medium from the present point of view but it cannot solve environmental problems in total because hot-water even when heated to 90 °C, filtered to 0.2 μm, and UV treated at the surface could pick up microorganisms from near-surface snow and circulate them in great volume through the borehole. Another negative impact of hot-water circulation medium is thermal pollution of subglacial water. The new approach to Antarctic subglacial lakes exploration is presented by sampling technology with recoverable autonomous sonde which is equipped by two hot-points with heating elements located on the bottom and top sides of the sonde. All down-hole sonde components will be sterilized by combination of chemical wash, HPV and UV sterilization prior using. At the beginning of the summer season sonde is installed on the surface of the

  10. 77 FR 31044 - Permits Issued Under the Antarctic Conservation Act

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

    ... No: 2012-12616] NATIONAL SCIENCE FOUNDATION Permits Issued Under the Antarctic Conservation Act AGENCY: National Science Foundation. ACTION: Notice of permits issued under the Antarctic Conservation of 1978, Public Law 95-541. SUMMARY: The National Science Foundation (NSF) is required to publish...

  11. 76 FR 9849 - Comprehensive Environmental Evaluations for Antarctic Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-22

    ... Comprehensive Environmental Evaluations for Antarctic Activities SUMMARY: The Department of State gives notice of the availability of two draft Comprehensive Environmental Evaluations (CEEs) for activities.... SUPPLEMENTARY INFORMATION: Article 3 of Annex I to the Protocol on Environmental Protection to the Antarctic...

  12. Transcriptome of the Antarctic brooding gastropod mollusc Margarella antarctica.

    PubMed

    Clark, Melody S; Thorne, Michael A S

    2015-12-01

    454 RNA-Seq transcriptome data were generated from foot tissue of the Antarctic brooding gastropod mollusc Margarella antarctica. A total of 6195 contigs were assembled de novo, providing a useful resource for researchers with an interest in Antarctic marine species, phylogenetics and mollusc biology, especially shell production.

  13. Cross-disciplinarity in the advance of Antarctic ecosystem research.

    PubMed

    Gutt, J; Isla, E; Bertler, A N; Bodeker, G E; Bracegirdle, T J; Cavanagh, R D; Comiso, J C; Convey, P; Cummings, V; De Conto, R; De Master, D; di Prisco, G; d'Ovidio, F; Griffiths, H J; Khan, A L; López-Martínez, J; Murray, A E; Nielsen, U N; Ott, S; Post, A; Ropert-Coudert, Y; Saucède, T; Scherer, R; Schiaparelli, S; Schloss, I R; Smith, C R; Stefels, J; Stevens, C; Strugnell, J M; Trimborn, S; Verde, C; Verleyen, E; Wall, D H; Wilson, N G; Xavier, J C

    2017-09-29

    The biodiversity, ecosystem services and climate variability of the Antarctic continent and the Southern Ocean are major components of the whole Earth system. Antarctic ecosystems are driven more strongly by the physical environment than many other marine and terrestrial ecosystems. As a consequence, to understand ecological functioning, cross-disciplinary studies are especially important in Antarctic research. The conceptual study presented here is based on a workshop initiated by the Research Programme Antarctic Thresholds - Ecosystem Resilience and Adaptation of the Scientific Committee on Antarctic Research, which focussed on challenges in identifying and applying cross-disciplinary approaches in the Antarctic. Novel ideas and first steps in their implementation were clustered into eight themes. These ranged from scale problems, through risk maps, and organism/ecosystem responses to multiple environmental changes and evolutionary processes. Scaling models and data across different spatial and temporal scales were identified as an overarching challenge. Approaches to bridge gaps in Antarctic research programmes included multi-disciplinary monitoring, linking biomolecular findings and simulated physical environments, as well as integrative ecological modelling. The results of advanced cross-disciplinary approaches can contribute significantly to our knowledge of Antarctic and global ecosystem functioning, the consequences of climate change, and to global assessments that ultimately benefit humankind. Copyright © 2017. Published by Elsevier B.V.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Revision of Eocene Antarctic carpet sharks (Elasmobranchii, Orectolobiformes) from Seymour Island, Antarctic Peninsula.

    PubMed

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

    2017-01-01

    Seymour Island, Antarctic Peninsula, was once called the 'Rosetta Stone' of Southern Hemisphere palaeobiology, because this small island provides the most complete and richly fossiliferous Palaeogene sequence in Antarctica. Among fossil marine vertebrate remains, chondrichthyans seemingly were dominant elements in the Eocene Antarctic fish fauna. The fossiliferous sediments on Seymour Island are from the La Meseta Formation, which was originally divided into seven stratigraphical levels, TELMs 1-7 (acronym for Tertiary Eocene La Meseta) ranging from the upper Ypresian (early Eocene) to the late Priabonian (late Eocene). Bulk sampling of unconsolidated sediments from TELMs 5 and 6, which are Ypresian (early Eocene) and Lutetian (middle Eocene) in age, respectively, yielded very rich and diverse chondrichthyan assemblages including over 40 teeth of carpet sharks representing two new taxa, Notoramphoscyllium woodwardi gen. et sp. nov. and Ceolometlaouia pannucae gen. et sp. nov. Two additional teeth from TELM 5 represent two different taxa that cannot be assigned to any specific taxon and thus are left in open nomenclature. The new material not only increases the diversity of Eocene Antarctic selachian faunas but also allows two previous orectolobiform records to be re-evaluated. Accordingly, Stegostoma cf. faciatum is synonymized with Notoramphoscyllium woodwardi gen. et sp. nov., whereas Pseudoginglymostoma cf. brevicaudatum represents a nomen dubium. The two new taxa, and probably the additional two unidentified taxa, are interpreted as permanent residents, which most likely were endemic to Antarctic waters during the Eocene and adapted to shallow and estuarine environments.

  16. The ANGWIN Antarctic Research Program: First Results on Coordinated Trans-Antarctic Gravity Wave Measurements

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Pautet, P. D.; Zhao, Y.; Nakamura, T.; Ejiri, M. K.; Murphy, D. J.; Moffat-Griffin, T.; Kavanagh, A. J.; Takahashi, H.; Wrasse, C. M.

    2014-12-01

    ANGWIN (ANrctic Gravity Wave Instrument Network) is a new "scientist driven" research program designed to develop and utilize a network of Antarctic atmospheric gravity wave observatories, operated by different nations working together in a spirit of close scientific collaboration. Our research plan has brought together colleagues from several international institutions, all with a common goal to better understand the large "continental-scale" characteristics and impacts of gravity waves on the Mesosphere and Lower Thermosphere (MLT) environment over Antarctica. ANGWIN combines complementary measurements obtained using new and existing aeronomy instrumentation with new modeling capabilities. To date, our activities have focused on developing coordinated airglow image data of gravity waves in the MLT region at the following sites: McMurdo (US), Syowa (Japan), Davis (Australia), Halley (UK), Rothera (UK), and Comandante Ferraz (Brazil). These are all well-established international research stations that are uniformly distributed around the continental perimeter, and together with ongoing measurements at South Pole Station they provide unprecedented coverage of the Antarctic gravity wave field and its variability during the extended polar winter season. This presentation introduces the ANGWIN program and research goals, and presents first results on trans-Antarctic wave propagation using coordinated measurements during the winter season 2011. We also discuss future plans for the development of this exciting program for Antarctic research.

  17. QsdH, a Novel AHL Lactonase in the RND-Type Inner Membrane of Marine Pseudoalteromonas byunsanensis Strain 1A01261

    PubMed Central

    Huang, Wei; Lin, Yongjun; Yi, Shuyuan; Liu, Pengfu; Shen, Jie; Shao, Zongze; Liu, Ziduo

    2012-01-01

    N-acyl-homoserine lactones (AHLs) are the main quorum-sensing (QS) signals in gram-negative bacteria. AHLs trigger the expression of genes for particular biological functions when their density reaches a threshold. In this study, we identified and cloned the qsdH gene by screening a genomic library of Pseudoalteromonas byunsanensis strain 1A01261, which has AHL-degrading activity. The qsdH gene encoded a GDSL hydrolase found to be located in the N-terminus of a multidrug efflux transporter protein of the resistance-nodulation-cell division (RND) family. We further confirmed that the GDSL hydrolase, QsdH, exhibited similar AHL-degrading activity to the full-length ORF protein. QsdH was expressed and purified to process the N-terminal signal peptide yielding a 27-kDa mature protein. QsdH was capable of inactivating AHLs with an acyl chain ranging from C4 to C14 with or without 3-oxo substitution. High-performance liquid chromatography (HPLC) and electrospray ionization-mass spectrometry (ESI-MS) analyses showed that QsdH functioned as an AHL lactonase to hydrolyze the ester bond of the homoserine lactone ring of AHLs. In addition, site-directed mutagenesis demonstrated that QsdH contained oxyanion holes (Ser-Gly-Asn) in conserved blocks (I, II, and III), which had important roles in its AHL-degrading activity. Furthermore, the lactonase activity of QsdH was slightly promoted by several divalent ions. Using in silico prediction, we concluded that QsdH was located at the first periplasmic loop of the multidrug efflux transporter protein, which is essential to substrate selectivity for these efflux pumps. These findings led us to assume that the QsdH lactonase and C-terminal efflux pump might be effective in quenching QS of the P. byunsanensis strain 1A01261. Moreover, it was observed that recombinant Escherichia coli producing QsdH proteins attenuated the plant pathogenicity of Erwinia carotovora, which might have potential to control of gram-negative pathogenic

  18. Solutions to problems of weathering in Antarctic eucrites

    NASA Technical Reports Server (NTRS)

    Strait, Melissa M.

    1990-01-01

    Neutron activation analysis was performed for major and trace elements on a suite of eucrites from both Antarctic and non-Antarctic sources. The chemistry was examined to see if there was an easy way to distinguish Antarctic eucrites that had been disturbed in their trace elements systematics from those that had normal abundances relative to non-Antarctic eucrites. There was no simple correlation found, and identifying the disturbed meteorites still remains a problem. In addition, a set of mineral separates from an eucrite were analyzed. The results showed no abnormalities in the chemistry and provides a possible way to use Antarctic eucrites that were disturbed in modelling of the eucrite parent body.

  19. Mapping Antarctic Megadunes and Other Accumulation-related Features on the East Antarctic Plateau

    NASA Astrophysics Data System (ADS)

    Fahnestock, M. A.; Shuman, C.; Scambos, T.; Albert, M.; Haran, T.; Courville, Z.; Bauer, R.

    2005-12-01

    Using both field observations and continent-wide remote sensing data sets, we characterize accumulation-related features on the Plateau, including the extent, variability, and likely formation processes of megadunes. A new 125-meter MODIS-based Mosaic of Antarctica (MOA), coupled with SAR imagery from the Radarsat Antarctic Mapping Mission (RAMP; Jezek,1999) elevation profiles from ICESat, and compilations of mean accumulation (e.g., Vaughan et al., 1999; Davis et al., 2005) form the basis for the remote sensing analysis. Field measurements from ground penetrating radar, automatic weather stations, surface photos, snowpits, and shallow cores in two field seasons (November-December 2002 and January 2004) provide in situ and subsurface information on dune structure and a context for interpretation of fused remote sensing measurements. Antarctic megadunes are linear stripe accumulations of fine-grained, wind-packed snow, forming 2 - 8 meter high, 1-2km wide ridges separated by 2-6 km of near-zero-accumulation `glaze' regions. Glaze surfaces overlie extremely metamorphosed firn, characterized by very coarse recrystallized grains and poorly expressed layering; remote sensing indicates that this type of firn is spatially dominant in a number of areas on the Plateau. Megadunes occur in high-altitude (2000-3500m ASL) low-accumulation (<5cm water-equivalent/year) regions of the East Antarctic plateau, away from ridge crests and dome summits. They comprise a total area of 1.2 million km2, or roughly 20% of the East Antarctic surface (higher than earlier estimates) but are absent (in the present climate) from the West Antarctic or Greeland Ice Sheet surfaces. Ground-penetrating radar profiles coupled with simple models of snow accumulation reveal that the accumulation rate and the surface profile shape in the windward direction are intimately related for megadunes; this relationship is extended to all megadune areas by a comparison of ICESat profiles, the RAMP backscatter

  20. Examining Differences in Arctic and Antarctic Sea Ice Change

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.; Rigor, I. G.; Clemente-Colon, P.; Neumann, G.; Li, P.

    2015-12-01

    The paradox of the rapid reduction of Arctic sea ice versus the stability (or slight increase) of Antarctic sea ice remains a challenge in the cryospheric science research community. Here we start by reviewing a number of explanations that have been suggested by different researchers and authors. One suggestion is that stratospheric ozone depletion may affect atmospheric circulation and wind patterns such as the Southern Annular Mode, and thereby sustaining the Antarctic sea ice cover. The reduction of salinity and density in the near-surface layer may weaken the convective mixing of cold and warmer waters, and thus maintaining regions of no warming around the Antarctic. A decrease in sea ice growth may reduce salt rejection and upper-ocean density to enhance thermohalocline stratification, and thus supporting Antarctic sea ice production. Melt water from Antarctic ice shelves collects in a cool and fresh surface layer to shield the surface ocean from the warmer deeper waters, and thus leading to an expansion of Antarctic sea ice. Also, wind effects may positively contribute to Antarctic sea ice growth. Moreover, Antarctica lacks of additional heat sources such as warm river discharge to melt sea ice as opposed to the case in the Arctic. Despite of these suggested explanations, factors that can consistently and persistently maintains the stability of sea ice still need to be identified for the Antarctic, which are opposed to factors that help accelerate sea ice loss in the Arctic. In this respect, using decadal observations from multiple satellite datasets, we examine differences in sea ice properties and distributions, together with dynamic and thermodynamic processes and interactions with land, ocean, and atmosphere, causing differences in Arctic and Antarctic sea ice change to contribute to resolving the Arctic-Antarctic sea ice paradox.

  1. STUDIES ON THE FILTRABILITY OF BACTERIUM GRANULOSIS

    PubMed Central

    Olitsky, P. K.; Knutti, R. E.; Tyler, J. R.

    1931-01-01

    The evidence hitherto reported concerning the filtration of trachomatous material, and inoculation of man and monkeys with the filtrates points to the conclusion that the incitant of trachoma is not, as a rule, filtrable. Our findings confirm this view and indicate further that no virus causing the disease is adsorbed to Bacterium granulosis. On the other hand, Bacterium granulosis itself in heavy suspensions is irregularly filtrable through Berkefeld V candles, like some other bacteria (14), but it is present in the filtrates in only small numbers. When suspensions were used of trachomatous human and monkey tissues, which contain much fewer organisms than do actual cultures, Bacterium granulosis was never recovered from the filtrates. The conception that trachoma is a disease caused by an ultramicroscopic virus is based on (a) the positive results of filtration in two animals, as reported by Nicolle and his coworkers, and (b) the presence of so called "inclusion bodies" in some of the cells of the lesions. One can state definitely that the evidence is now greatly against the filtrability of the etiological agent of trachoma. Furthermore, filtrability does not in itself suffice for the classification of an agent as an ultramicroscopic virus. Concerning (b), a vast literature has accumulated which indicates that the "inclusion bodies" of trachoma are not specific for the disease and that the bodies themselves may be bacterial in origin (15). We have not as yet found bodies of the kind characteristic of many filtrable viruses in the tissues of man or of monkeys with the experimental disease. PMID:19869939

  2. Ocean processes at the Antarctic continental slope.

    PubMed

    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.

  3. Numerical model of circumpolar Antarctic ice shelves

    SciTech Connect

    Johnson, R.C.

    1985-01-01

    Extensive floating ice shelves in the Antarctic have been proposed to explain the discrepancies between Pleistocene high sea levels shown by dated coral reefs and coeval low sea levels inferred from glacial ice volumes calculated from oxygen isotope ratios in deep sea cores. A numerical model using the floating shelf creep analysis of Weertman (1957) has provided a plausible basis for the acceptance of such shelves. Shelf outer limits were set at 55/sup 0/S in East Antarctica and 58/sup 0/S in West Antarctica, based in part on diatom-deficient deep sea sediments deposited prior to the Holocene. Precipitation varied from 10 gm cm/sup -2/yr/sup -1/ at 75/sup 0/S to 80 gm cm/sup -2/yr/sup -1/ at 55/sup 0/S. Mean air temperatures varied from -35/sup 0/C at the 75/sup 0/S coast to -17/sup 0/C at the outer limits. Isotope ratios were those of present Antarctic precipitation at corresponding model shelf temperatures. In the calculation, a steady state is assumed. Integration begins at the coast with summation over successive years as creep and continental ice discharge move the integration element to the outer limits. The oceanic oxygen isotope ratio change required by the discrepancies in the record is 0.40 to 0.50 ppmil. Using the flow law constant of 4.2 and a creep activation energy of 134 kjoules mol/sup -1/, the resulting change is 0.44 ppmil. Difference results reflect the uncertainties associated with the critical creep constants used in the modeling. Nevertheless, the results suggest that a quantity of Antarctic shelf ice comparable to ice volumes in major Northern glacial areas existed at times during the Pleistocene.

  4. Following the trail of antarctic winds

    SciTech Connect

    Mroz, E.J.; Alei, M.; Cappis, J.H.; Guthals, P.R.; Mason, A.S.; Rokop, D.J.

    1986-01-01

    The transport of tropospheric air masses from the north to the south (longitudinal transport) is responsible for bringing aerosols and trace gases to Antarctica from the lower latitudes. The atmospheric materials and pollutants from both natural and anthropogenic sources may then become part of the geological climatic record if they are trapped in the southern polar ice sheet. If one is to use this record to evaluate the potential greenhouse and albedo effects of air pollutants on global climate, one needs to understand the transport mechanisms involved. The antarctic tracer experiment was designed to improve the scientific comprehension of these north-south transport processes by the use of unique atmospheric tracers. Heavy methanes were chosen to track the antarctic winds. These are the heavy isotopic analogues of methane - so named because they are composed of the heavy isotopes of carbon and hydrogen, namely carbon-13 and deuterium. The authors released specific amount of /sup 13/CD/sub 4/ and /sup 12/CD/sub 4/ gas into the antarctic atmosphere and subsequently conducted air and surface sampling in search of the tracer gas. Sampling and mass spectrometric analysis techniques developed by Los Alamos National Laboratory's Isotope and Nuclear Chemistry Division can detect these tracers in quantities as small as a few parts in 10/sup 17/ in air. Because of their extremely low natural abundance, their long atmospheric lifetime, and the high sensitivity for their detection, these isotopically unique methanes are ideal for experimentally tracking air masses in Antarctica over long periods of time and more than 4000 kilometers from the release point. Results are discussed.

  5. Ocean processes at the Antarctic continental slope

    PubMed Central

    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

    2014-01-01

    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. PMID:24891389

  6. The Antarctic Ozone Hole: An Update

    NASA Technical Reports Server (NTRS)

    Douglass, Anne R.; Newman, Paul A.; Solomon, Susan

    2014-01-01

    The stratospheric ozone hole, an annual occurrence during austral spring, is caused by heterogeneous conversion of hydrogen chloride and chlorine nitrate to chlorine radicals. These reactions take place of polar stratospheric cloud particles in the cold, isolate Antarctic winter vortex. The chlorine radicals participate in chemical reactions that rapidly deplete ozone when sunlight returns at the end of polar night. International agreements eliminated production of the culprit anthropogenic chlorofluorocarbons in the late 1990s, but due to their long stratospheric lifetime (50-100 years), the ozone hole will continue its annual appearance for years to come.

  7. Ultraviolet radiation levels during the Antarctic spring

    NASA Technical Reports Server (NTRS)

    Frederick, John E.; Snell, Hilary E.

    1988-01-01

    The decrease in atmospheric ozone over Antarctica during spring implies enhanced levels of ultraviolet (UV) radiation received at the earth's surface. Model calculations show that UV irradiances encountered during the occurrence of an Antarctic 'ozone hole' remain less than those typical of a summer solstice at low to middle latitudes. However, the low ozone amounts observed in October 1987 imply biologically effective irradiances for McMurdo Station, Antarctica, that are comparable to or greater than those for the same location at December solstice. Life indigenous to Antarctica thereby experiences a greatly extended period of summerlike UV radiation levels.

  8. Portable Habitat for Antarctic Scientific Research (PHASR)

    NASA Technical Reports Server (NTRS)

    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.

  9. Measurements of ethane in Antarctic ice cores

    NASA Astrophysics Data System (ADS)

    Verhulst, K. R.; Fosse, E. K.; Aydin, K. M.; Saltzman, E. S.

    2011-12-01

    Ethane is one of the most abundant hydrocarbons in the atmosphere. The major ethane sources are fossil fuel production and use, biofuel combustion, and biomass-burning emissions and the primary loss pathway is via reaction with OH. A paleoatmospheric ethane record would be useful as a tracer of biomass-burning emissions, providing a constraint on past changes in atmospheric methane and methane isotopes. An independent biomass-burning tracer would improve our understanding of the relationship between biomass burning and climate. The mean annual atmospheric ethane level at high southern latitudes is about 230 parts per trillion (ppt), and Antarctic firn air measurements suggest that atmospheric ethane levels in the early 20th century were considerably lower (Aydin et al., 2011). In this study, we present preliminary measurements of ethane (C2H6) in Antarctic ice core samples with gas ages ranging from 0-1900 C.E. Samples were obtained from dry-drilled ice cores from South Pole and Vostok in East Antarctica, and from the West Antarctic Ice Sheet Divide (WAIS-D). Gases were extracted from the ice by melting under vacuum in a glass vessel sealed by indium wire and were analyzed using high resolution GC/MS with isotope dilution. Ethane levels measured in ice core samples were in the range 100-220 ppt, with a mean of 157 ± 45 ppt (n=12). System blanks contribute roughly half the amount of ethane extracted from a 300 g ice core sample. These preliminary data exhibit a temporal trend, with higher ethane levels from 0-900 C.E., followed by a decline, reaching a minimum between 1600-1700 C.E. These trends are consistent with variations in ice core methane isotopes and carbon monoxide isotopes (Ferretti et al., 2005, Wang et al., 2010), which indicate changes in biomass burning emissions over this time period. These preliminary data suggest that Antarctic ice core bubbles contain paleoatmospheric ethane levels. With further improvement of laboratory techniques it appears

  10. Temperature response of Antarctic cryptoendolithic photosynthetic microorganisms

    NASA Technical Reports Server (NTRS)

    Ocampo-Friedmann, R.; Meyer, M. A.; Chen, M.; Friedmann, E. I.

    1988-01-01

    Growth responses to temperatures between 12.5 [degrees] C and 25 degrees C were determined for five photosynthetic microorganisms isolated from the Ross Desert cryptoendolithic community. Among eukaryotic algae, two strains of Trebouxia sp. have an upper temperature limit of 20 degrees C, and two strains of Hemichloris antarctica of 25 degrees C. The cyanobacterium Chroococcidiopsis sp., in contrast, grows at temperatures above 25 degrees C. These and earlier studies suggest that the eukaryotic algae of the Antarctic cryptoendolithic community have an upper temperature limit near 25 degrees C.

  11. Temperature response of Antarctic cryptoendolithic photosynthetic microorganisms

    NASA Technical Reports Server (NTRS)

    Ocampo-Friedmann, R.; Meyer, M. A.; Chen, M.; Friedmann, E. I.

    1988-01-01

    Growth responses to temperatures between 12.5 [degrees] C and 25 degrees C were determined for five photosynthetic microorganisms isolated from the Ross Desert cryptoendolithic community. Among eukaryotic algae, two strains of Trebouxia sp. have an upper temperature limit of 20 degrees C, and two strains of Hemichloris antarctica of 25 degrees C. The cyanobacterium Chroococcidiopsis sp., in contrast, grows at temperatures above 25 degrees C. These and earlier studies suggest that the eukaryotic algae of the Antarctic cryptoendolithic community have an upper temperature limit near 25 degrees C.

  12. The ARM West Antarctic Radiation Experiment (AWARE)

    NASA Astrophysics Data System (ADS)

    Scott, R. C.; Lubin, D.; Bromwich, D. H.; Vogelmann, A. M.; Verlinde, J.; Russell, L. M.

    2016-12-01

    West Antarctica is one of the most rapidly warming regions on Earth, and its changing climate in both atmosphere and ocean is linked to loss of Antarctic ice mass and global sea level rise. The specific mechanisms for West Antarctic Ice Sheet (WAIS) warming are not fully understood, but are hypothesized to involve linkage between moisture from Southern Ocean storm tracks and the surface energy balance over the WAIS, and related teleconnections with subtropical and tropical meteorology. This present lack of understanding has motivated a climate science and cloud physics campaign jointly supported by the US National Science Foundation (NSF) and Department of Energy (DOE), called the Atmospheric Radiation Measurement Program (ARM) West Antarctic Radiation Experiment (AWARE). The DOE's second ARM Mobile Facility (AMF2) was deployed to McMurdo Station on Ross Island in November 2015 and will operate through December 2016. The AMF2 includes (1) cloud research radars, both scanning and zenith, operating in the Ka- and X-bands, (2) high spectral resolution and polarized micropulse lidars, and (3) a suite of shortwave and longwave broadband and spectral radiometers. A second suite of instruments is deployed at the WAIS Divide Ice Camp on the West Antarctic plateau during December 2015 and January 2016. The WAIS instrument suite provides (1) measurement of all surface energy balance components, (2) a polarized micropulse lidar and shortwave spectroradiometer, (3) microwave total water column measurement, and (4) four times daily rawinsonde launches which are the first from West Antarctica since 1967. There is a direct linkage between the WAIS instrument suite and the AMF2 at McMurdo, in that air masses originating in Southern Ocean storm tracks that are driven up over the WAIS often subsequently descend over the Ross Ice Shelf and arrive at Ross Island. Preliminary data are already illustrating (1) the prevalence of single- versus mixed-phase clouds and their role in the

  13. Terrestrial and exposure histories of Antarctic meteorites

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.

    1986-01-01

    Records of cosmogenic effects were studied in a large suite of Antarctic meteorites. The cosmogenic nuclide measurements together with cosmic ray track measurements on Antartic meteorites provide information such as exposure age, terrestrial age, size and depth in meteoroid or parent body, influx rate in the past, and pairing. The terrestrail age is the time period between the fall of the meteorite on the Earth and the present. To define terrestrial age, two or more nuclides with different half-lives and possibly noble gases are required. The cosmogenic radionuclides used are C-14, Kr-81, Cl-36, Al-26, Be-10, Mn-53, and K-40.

  14. Automatic focusing system of BSST in Antarctic

    NASA Astrophysics Data System (ADS)

    Tang, Peng-Yi; Liu, Jia-Jing; Zhang, Guang-yu; Wang, Jian

    2015-10-01

    Automatic focusing (AF) technology plays an important role in modern astronomical telescopes. Based on the focusing requirement of BSST (Bright Star Survey Telescope) in Antarctic, an AF system is set up. In this design, functions in OpenCV is used to find stars, the algorithm of area, HFD or FWHM are used to degree the focus metric by choosing. Curve fitting method is used to find focus position as the method of camera moving. All these design are suitable for unattended small telescope.

  15. NASA finds Shrimp Under Antarctic Ice [Video

    NASA Image and Video Library

    2017-09-27

    At a depth of 600 feet beneath the West Antarctic ice sheet, a small shrimp-like creature managed to brighten up an otherwise gray polar day in late November 2009. This critter is a three-inch long Lyssianasid amphipod found beneath the Ross Ice Shelf, about 12.5 miles away from open water. NASA scientists were using a borehole camera to look back up towards the ice surface when they spotted this pinkish-orange creature swimming beneath the ice. Credit: NASA

  16. Ultraviolet radiation levels during the Antarctic spring

    NASA Technical Reports Server (NTRS)

    Frederick, John E.; Snell, Hilary E.

    1988-01-01

    The decrease in atmospheric ozone over Antarctica during spring implies enhanced levels of ultraviolet (UV) radiation received at the earth's surface. Model calculations show that UV irradiances encountered during the occurrence of an Antarctic 'ozone hole' remain less than those typical of a summer solstice at low to middle latitudes. However, the low ozone amounts observed in October 1987 imply biologically effective irradiances for McMurdo Station, Antarctica, that are comparable to or greater than those for the same location at December solstice. Life indigenous to Antarctica thereby experiences a greatly extended period of summerlike UV radiation levels.

  17. New records of Antarctic and Sub-Antarctic sea anemones (Cnidaria, Anthozoa, Actiniaria and Corallimorpharia) from the Weddell Sea, Antarctic Peninsula, and Scotia Arc.

    PubMed

    Rodríguez, Estefanía

    2013-01-01

    Herein we provide new records for 22 Antarctic species of sea anemone sensu lato (Anthozoa: Actiniaria and Corallimorpharia) from the Weddell Sea, Antarctic Peninsula, and the Scotia Sea. We provided short descriptions, images of the external morphology of preserved specimens (but also of living specimens in most cases), cnida data, and distribution maps for each studied species. New records are presented for nine species in the Weddell Sea and the geographic or bathymetric distributions for 19 of the 22 studied species are extended.

  18. Detection of Salmonella bacterium in drinking water using microring resonator.

    PubMed

    Bahadoran, Mahdi; Noorden, Ahmad Fakhrurrazi Ahmad; Mohajer, Faeze Sadat; Abd Mubin, Mohamad Helmi; Chaudhary, Kashif; Jalil, Muhammad Arif; Ali, Jalil; Yupapin, Preecha

    2016-01-01

    A new microring resonator system is proposed for the detection of the Salmonella bacterium in drinking water, which is made up of SiO2-TiO2 waveguide embedded inside thin film layer of the flagellin. The change in refractive index due to the binding of the Salmonella bacterium with flagellin layer causes a shift in the output signal wavelength and the variation in through and drop port's intensities, which leads to the detection of Salmonella bacterium in drinking water. The sensitivity of proposed sensor for detecting of Salmonella bacterium in water solution is 149 nm/RIU and the limit of detection is 7 × 10(-4)RIU.

  19. Drag coefficients for winter Antarctic pack ice

    NASA Technical Reports Server (NTRS)

    Wamser, Christian; Martinson, Douglas G.

    1993-01-01

    Air-ice and ice-water drag coefficients referenced to 10-m-height winds for winter Antarctic pack ice based on measurements made from R/V Polarstern during the Winter Weddell Sea Project, 1986 (WWSP-86), and from R/V Akademik Fedorov during the Winter Weddell Gyre Study, 1989 (WWGS-89), are presented. The optimal values of the air-ice drag coefficients, made from turbulent flux measurements, are (1.79 +/- 0.06) x 10 exp -3 for WWSP-86 and (1.45 +/- 0.09) x 10 exp -3 for WWGS-89. A single ice-water drag coefficient for both WWSP-86 and WWGS-89, estimated from periods of ice drift throught to represent free-drift conditions, is (1.13 +/- 0.26) x 10 exp -3, and the ice-water turning angle is 18 +/- 18 deg. It is suggested that for a typical Antarctic winter pack ice cover, the ice cover reduces the momentum flux from the atmosphere to the ocean by about 33 percent.

  20. CHAMP Magnetic Anomalies of the Antarctic Crust

    NASA Technical Reports Server (NTRS)

    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.

  1. Widespread Antarctic glaciation during the Late Eocene

    NASA Astrophysics Data System (ADS)

    Carter, Andrew; Riley, Teal R.; Hillenbrand, Claus-Dieter; Rittner, Martin

    2017-01-01

    Marine sedimentary rocks drilled on the southeastern margin of the South Orkney microcontinent in Antarctica (Ocean Drilling Program Leg 113 Site 696) were deposited between ∼36.5 Ma to 33.6 Ma, across the Eocene-Oligocene climate transition. The recovered rocks contain abundant grains exhibiting mechanical features diagnostic of iceberg-rafted debris. Sand provenance based on a multi-proxy approach that included petrographic analysis of over 275,000 grains, detrital zircon geochronology and apatite thermochronometry rule out local sources (Antarctic Peninsula or the South Orkney Islands) for the material. Instead the ice-transported grains show a clear provenance from the southern Weddell Sea region, extending from the Ellsworth-Whitmore Mountains of West Antarctica to the coastal region of Dronning Maud Land in East Antarctica. This study provides the first evidence for a continuity of widespread glacier calving along the coastline of the southern Weddell Sea embayment at least 2.5 million yrs before the prominent oxygen isotope event at 34-33.5 Ma that is considered to mark the onset of widespread glaciation of the Antarctic continent.

  2. Mass balance of the Antarctic ice sheet.

    PubMed

    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.

  3. Extremophiles in an Antarctic Marine Ecosystem

    PubMed Central

    Dickinson, Iain; Goodall-Copestake, William; Thorne, Michael A.S.; Schlitt, Thomas; Ávila-Jiménez, Maria L.; Pearce, David A.

    2016-01-01

    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. PMID:27681902

  4. Matrix-bound phosphine in Antarctic biosphere.

    PubMed

    Zhu, Renbin; Sun, Liguang; Kong, Deming; Geng, Jinju; Wang, Ning; Wang, Qiang; Wang, Xiaorong

    2006-08-01

    Phosphine (PH(3)) is a natural gaseous carrier of phosphorus in its geochemical cycles, and it might be of importance to the phosphorus balance of natural ecosystem. For the first time phosphine levels were investigated in the Earth's coldest, driest, and most southerly Antarctic biosphere. Matrix-bound phosphine (MBP) was found in sea animal guanos, ornithogenic sediments and soils. Phosphine concentrations varied with different sea animal guanos. Average phosphine concentrations in empire penguin, gentoo penguin, sea lion, skua and gull guanos were 2.54+/-1.28 ng kg(-1), 6.21+/-2.15 ng kg(-1), 9.12+/-4.66 ng kg(-1), 11.90+/-1.29 ng kg(-1) and 14.55+/-6.74 ng kg(-1), respectively. The contents of phosphorus in these various matrixes have an important effect on MBP concentrations. The levels of phosphine appeared an increasing tendency with the content of TP, IP and OP in sea animal guanos, ornithogenic sediments or soils. The correlation between PH(3) and Fe, Mn, Al in these matrixes was also analyzed and discussed. Phosphine showed an obviously positive correlation with Fe in sea animal guanos. However, excessively high Fe, Al and Mn may inhibit the formation of PH(3) in the ornithogenic soils or sediments in the Antarctic biosphere.

  5. Formation of HCl in the Antarctic atmosphere

    NASA Astrophysics Data System (ADS)

    Legrand, Michel R.; Delmas, Robert J.

    1988-06-01

    The spatiotemporal variations of the Cl/Na ratio and other major chemical parameters are reported for several hundred samples collected in snow pits or from firn and ice cores at several locations on the Antarctic coast and plateau. The Cl/Na weight ratio in snow is generally very close to that of bulk sea water near the coast and begins to increase at the edge of the Antarctic plateau. In central areas, both relatively high and very low values are observed, depending on the time period. Excess chloride and excess sodium are explained by the presence in snow of HCl or Na2SO4, respectively, formed by the reaction of excess sulfate with sea-salt particles in the aerosol phase. This reaction results in the release of gaseous HCl into the atmosphere. This reaction probably occurs more completely when weather conditions are calm and marine aerosol is aged. In central areas, this alteration of marine aerosol can lead to excess chloride of up to 50 percent of total chloride deposition, and Na2SO4 can be equivalent to the sulfuric acid deposition.

  6. A Standard Atmosphere of the Antarctic Plateau

    NASA Technical Reports Server (NTRS)

    Mahesh, Ashwin; Lubin, Dan

    2004-01-01

    Climate models often rely on standard atmospheres to represent various regions; these broadly capture the important physical and radiative characteristics of regional atmospheres, and become benchmarks for simulations by researchers. The high Antarctic plateau is a significant region of the earth for which such standard atmospheres are as yet unavailable. Moreover, representative profiles from atmospheres over other regions of the planet, including &om the northern high latitudes, are not comparable to the atmosphere over the Antarctic plateau, and are therefore only of limited value as substitutes in climate models. Using data from radiosondes, ozonesondes and satellites along with other observations from South Pole station, typical seasonal atmospheric profiles for the high plateau are compiled. Proper representations of rapidly changing ozone concentrations (during the ozone hole) and the effect of surface elevation on tropospheric temperatures are discussed. The differences between standard profiles developed here and the most similar standard atmosphere that already exists - namely, the Arctic Winter profile - suggest that these new profiles will be extremely useful to make accurate representations of the atmosphere over the high plateau.

  7. Extracellular proteases from eight psychrotolerant Antarctic strains.

    PubMed

    Vazquez, Susana C; Coria, Silvia H; MacCormack, Walter P

    2004-01-01

    Extracellular proteases from 8 Antarctic psychrotolerant Pseudomonas sp. strains were purified and characterised. All of them are neutral metalloproteases, have an apparent molecular mass of 45kDa, optimal activity at 40 degrees C and pH 7-9, retaining significant activity at pH 5-11. With the exception of P96-18, which is less stable, all retain more than 50% activity after 3 h of incubation at pH 5-9 and show low thermal stability (their half-life times range from 20 to 60 min at 40 degrees C and less than 5 min at 50 degrees C). These proteases can be used in commercial processes carried out at neutral pH and moderate temperatures, and are of special interest for their application in mixtures of enzymes where final thermal selective inactivation is needed. Results also highlight the relevance of Antarctic biotopes for the isolation of protease-producing enzymes active at low temperatures.

  8. Quantitative characterization of the Antarctic ozone hole

    NASA Technical Reports Server (NTRS)

    Ito, T.; Sakoda, Y.; Matsubara, K.; Takao, T.; Akagi, K.; Watanabe, Y.; Shibata, S.; Naganuma, H.

    1994-01-01

    The long-term evolution of the Antarctic ozone hole is studied based on the TOMS data and the JMA data-set of stratospheric temperature in relation with the possible role of polar stratospheric clouds (PSC's). The effective mass of depleted ozone in the ozone hole at its annual mature stage reached a historical maximum of 55 Mt in 1991, 4.3 times larger than in 1981. The ozone depletion rate during 30 days before the mature ozone hole does not show any appreciable long-term trend but the interannual fluctuations do, ranging from 0.169 to 0.689 Mt/day with the average of 0.419 Mt/day for the period of 1979 - 1991. The depleted ozone mass has the highest correlation with the region below 195 K on the 30 mb surface in June, whereas the ozone depletion rate correlates most strongly with that in August. The present result strongly suggests that the long-term evolution of the mature ozone hole is caused both by the interannual change of the latitudinal coverage of the early PSC's, which may control the latitude and date of initiation of ozone decrease, and by that of the spatial coverage of the mature PSC's which may control the ozone depletion rate in the Antarctic spring.

  9. Mapping Antarctic grounding lines from Cryosat-2

    NASA Astrophysics Data System (ADS)

    Wouters, B.; Bamber, J. L.

    2014-12-01

    The grounding zone (GZ) of the Antarctic ice sheet is a critical boundary for assessing the mass of ice leaving the continent and the stability (or lack thereof) of the inland, grounded ice sheet. It marks the transition between ice that can contribute to sea level and that which already has. Ice shelf basal melt rates are a maximum close the GZ and can have an important influence on inland flow. Changes in the position of the GZ for an ice stream resting on a bed with a retrograde slope (deepening inland) can provide an early warning of an instability in flow or state transition. Several methods exists to monitor the GZ, however, to date, there has been no method for routinely and regularly monitoring the GZ, nor any method that can be applied unambiguously across its entirety around Antarctica. The CryoSat-2 mission provides year-round coverage of the ice sheets, at a high spatial resolution. On the Antarctic ice shelves, the 369 day repeat period of the observations leads to aliasing of tidal motion induced by ocean tides, resulting in distinct patterns in the CryoSat-2 elevation measurements. Here, we focus on the Filchner-Ronne ice shelf to demonstrate the potential of the Cryosat-2 observations to map the GZ, and compare our results with existing GZ estimates.

  10. Total and inorganic arsenic in Antarctic macroalgae.

    PubMed

    Farías, Silvia; Smichowski, Patricia; Vélez, Dinoraz; Montoro, Rosa; Curtosi, Antonio; Vodopívez, Cristian

    2007-10-01

    The Antarctic region offers unparalleled possibilities of investigating the natural distribution of metals and metalloids, such as arsenic. Total and inorganic As were analysed in nine species of Antarctic macroalgae collected during the 2002 summer season in the Potter Cove area at Jubany-Dallmann Station (South Shetland Islands, Argentinian Base). Total As was determined by inductively coupled plasma-optical emission spectrometry after microwave-assisted acid digestion. Inorganic As was determined by acid digestion, solvent extraction, flow injection-hydride generation-atomic absorption spectrometry. Total As ranged from 5.8 microg g(-1) dry weight (dw) (Myriogramme sp.) to 152 microg g(-1)dw (Himantothallus grandifolius). Total As concentrations were higher in Phaeophytes (mean+/-SD: 71+/-44 microg g(-1)dw) than in Rhodophytes (mean+/-SD: 15+/-11 microg g(-1)dw). Inorganic As ranged from 0.12 microg g(-1) (Myriogramme sp.) to 0.84 microg g(-1)dw (Phaeurus antarcticus). The percentage of inorganic As with respect to total As was 0.7 for Phaeophytes, but almost 4 times higher for Rhodophytes (2.6). The work discusses possible causes for the presence of As in marine organisms in that pristine environment.

  11. Drag coefficients for winter Antarctic pack ice

    NASA Technical Reports Server (NTRS)

    Wamser, Christian; Martinson, Douglas G.

    1993-01-01

    Air-ice and ice-water drag coefficients referenced to 10-m-height winds for winter Antarctic pack ice based on measurements made from R/V Polarstern during the Winter Weddell Sea Project, 1986 (WWSP-86), and from R/V Akademik Fedorov during the Winter Weddell Gyre Study, 1989 (WWGS-89), are presented. The optimal values of the air-ice drag coefficients, made from turbulent flux measurements, are (1.79 +/- 0.06) x 10 exp -3 for WWSP-86 and (1.45 +/- 0.09) x 10 exp -3 for WWGS-89. A single ice-water drag coefficient for both WWSP-86 and WWGS-89, estimated from periods of ice drift throught to represent free-drift conditions, is (1.13 +/- 0.26) x 10 exp -3, and the ice-water turning angle is 18 +/- 18 deg. It is suggested that for a typical Antarctic winter pack ice cover, the ice cover reduces the momentum flux from the atmosphere to the ocean by about 33 percent.

  12. When will the Antarctic Ozone Hole Recover?

    NASA Technical Reports Server (NTRS)

    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.

  13. Recovery of the Antarctic Ozone Hole

    NASA Technical Reports Server (NTRS)

    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.

  14. When Will the Antarctic Ozone Hole Recover?

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  15. Extremophiles in an Antarctic Marine Ecosystem.

    PubMed

    Dickinson, Iain; Goodall-Copestake, William; Thorne, Michael A S; Schlitt, Thomas; Ávila-Jiménez, Maria L; Pearce, David A

    2016-01-11

    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.

  16. Eukaryotes in Arctic and Antarctic cyanobacterial mats.

    PubMed

    Jungblut, Anne D; Vincent, Warwick F; Lovejoy, Connie

    2012-11-01

    Cyanobacterial mats are commonly found in freshwater ecosystems throughout the polar regions. Most mats are multilayered three-dimensional structures with the filamentous cyanobacteria embedded in a gel-like matrix. Although early descriptions mentioned the presence of larger organisms including metazoans living in the mats, there have been few studies specifically focused on the microbial eukaryotes, which are often small cells with few morphological features suitable for identification by microscopy. Here, we applied 18S rRNA gene clone library analysis to identify eukaryotes in cyanobacterial mat communities from both the Antarctic and the extreme High Arctic. We identified 39 ribotypes at the level of 99% sequence similarity. These consisted of taxa within algal and other protist groups including Chlorophyceae, Prasinophyceae, Ulvophyceae, Trebouxiophyceae, Bacillariophyceae, Chrysophyceae, Ciliophora, and Cercozoa. Fungi were also recovered, as were 21 metazoan ribotypes. The eukaryotic taxa appeared habitat-specific with little overlap between lake, pond, and ice shelf communities. Some ribotypes were common to both Arctic and Antarctic mats, suggesting global dispersal of these taxa and similarity in the environmental filters acting on protist communities. Many of these eukaryotic taxa likely benefit from protected, nutrient-rich microhabitats within the cyanobacterial mat environment.

  17. Distribution and abundance of Antarctic krill (Euphausia superba) along the Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Siegel, Volker; Reiss, Christian S.; Dietrich, Kimberly S.; Haraldsson, Matilda; Rohardt, Gerhard

    2013-07-01

    Net-based data on the abundance, distribution, and demographic patterns of Antarctic krill are quantified from a contemporaneous two ship survey of the Antarctic Peninsula during austral summer 2011. Two survey areas were sampled focussed on Marguerite Bay in the south, and the tip of the Antarctic Peninsula in the north. Data from 177 stations showed that the highest concentrations of krill were found in the southern sampling area. Differences between areas were associated with a few large catches of one year old krill found in anomalously warm and productive waters in Marguerite Bay, and small krill catches in the less-productive, offshore waters in the north. Estimated krill density across the survey area was 3.4 krill m-2, and was low compared to the long-term average of 45 krill m-2 for the Elephant Island area. Overall recruitment between the two survey regions was similar, but per capita recruitment was about 60% lower than historical mean recruitment levels measured at Elephant Island since the late 1970s. Demographic patterns showed small krill concentrated near the coast, and large krill concentrated offshore on the shelf and slope all along the survey area. The offshore distribution of adult krill was delineated by the warm (˜1 °C), low salinity (33.8) water at 30 m, suggesting that most krill were present shoreward of the southern boundary of Antarctic Circumpolar Current Front. Distributions of larvae indicated that three hotspot areas were important for the production of krill: slope areas outside Marguerite Bay and north of the South Shetland Islands, and near the coast around Antarctic Sound. Successful spawning, as inferred from larval abundance, was roughly coincident with the shelf break and not with inshore waters. Given the rapid changes in climate along the Antarctic Peninsula and the lower per capita recruitment observed in recent years, studies comparing and contrasting production, growth, and recruitment across the Peninsula will be

  18. Russian deep-sea investigations of Antarctic fauna

    NASA Astrophysics Data System (ADS)

    Malyutina, Marina

    2004-07-01

    A review of the Russian deep-sea investigation of Antarctic fauna beginning from the first scientific collection of Soviet whaling fleet expeditions 1946-1952 is presented. The paper deals with the following expeditions, their main tasks and results. These expeditions include three cruises of research vessel (R.V.) Ob in the Indian sector of the Antarctic and in the Southern Pacific (1955-1958); 11 cruises of the R.V. Akademik Kurchatov in the southern Atlantic (November-December 1971); 16 cruises of the R.V. Dmitriy Mendeleev in the Australia-New Zealand area and adjacent water of the Antarctic (December 1975-March 1976); 43 cruises of the R.V. Akademik Kurchatov in the southern Atlantic (October 1985-February 1986); and 43 cruises of the R.V. Dmitriy Mendeleev in the Atlantic sector of the South Ocean (January-May 1989). A list of the main publications on the benthic taxa collected during these expeditions with data of their distribution is presented. The results of Russian explorations of the Antarctic fauna are presented as theoretical conclusions in the following topics: (1) Vertical zonation in the distribution of the Antarctic deep-sea fauna; (2) Biogeographic division of the abyssal and hadal zones; (3) Origin of the Antarctic deep-sea fauna; (4) Distributional pathways of the Antarctic abyssal fauna through the World Ocean.

  19. Antarctic Crustal Thickness from Gravity Inversion

    NASA Astrophysics Data System (ADS)

    Vaughan, A. P.; Kusznir, N. J.; Ferraccioli, F.; Jordan, T. A.

    2013-12-01

    Using gravity anomaly inversion, we have produced the first comprehensive regional maps of crustal thickness and oceanic lithosphere distribution for Antarctica and the Southern Ocean. We determine Moho depth, crustal basement thickness, continental lithosphere thinning (1-1/β) and ocean-continent transition location using a 3D spectral domain gravity inversion method, which incorporates a lithosphere thermal gravity anomaly correction. The continental lithosphere thinning distribution, used to define the initial thermal model temperature perturbation is derived from the gravity inversion and uses no a priori isochron information; as a consequence the gravity inversion method provides a prediction of ocean-continent transition location, which is independent of ocean isochron information. The gravity anomaly contribution from ice thickness is included in the gravity inversion, as is the contribution from sediments which assumes a compaction controlled sediment density increase with depth. Data used in the gravity inversion are elevation and bathymetry, free-air gravity anomaly, the most recent Bedmap2 ice thickness and bedrock topography compilation south of 60 degrees south (Fretwell et al., 2013) and relatively sparse constraints on sediment thickness. Our gravity inversion study predicts thick crust (> 45 km) under interior East Antarctica penetrated by narrow continental rifts that feature relatively thinner crust. The East Antarctic Rift System (EARS) is a major Permian to Cretaceous age rift system that appears to extend from the continental margin at the Lambert Rift to the South Pole region, a distance of 2500 km. This is comparable in scale to the well-studied East African rift system. Intermediate crustal thickness with an inferred linear rift fabric is predicted under Coates Land. An extensive region of either thick oceanic crust or highly thinned continental crust is predicted offshore Oates Land and north Victoria Land, and also off West Antarctica

  20. Distinct molecular features facilitating ice-binding mechanisms in hyperactive antifreeze proteins closely related to an Antarctic sea ice bacterium.

    PubMed

    Banerjee, Rachana; Chakraborti, Pratim; Bhowmick, Rupa; Mukhopadhyay, Subhasish

    2015-01-01

    Antifreeze proteins or ice-binding proteins (IBPs) facilitate the survival of certain cellular organisms in freezing environment by inhibiting the growth of ice crystals in solution. Present study identifies orthologs of the IBP of Colwellia sp. SLW05, which were obtained from a wide range of taxa. Phylogenetic analysis on the basis of conserved regions (predicted as the 'ice-binding domain' [IBD]) present in all the orthologs, separates the bacterial and archaeal orthologs from that of the eukaryotes'. Correspondence analysis pointed out that the bacterial and archaeal IBDs have relatively higher average hydrophobicity than the eukaryotic members. IBDs belonging to bacterial as well as archaeal AFPs contain comparatively more strands, and therefore are revealed to be under higher evolutionary selection pressure. Molecular docking studies prove that the ice crystals form more stable complex with the bacterial as well as archaeal proteins than the eukaryotic orthologs. Analysis of the docked structures have traced out the ice-binding sites (IBSs) in all the orthologs which continue to facilitate ice-binding activity even after getting mutated with respect to the well-studied IBSs of Typhula ishikariensis and notably, all these mutations performing ice-binding using 'anchored clathrate mechanism' have been found to prefer polar and hydrophilic amino acids. Horizontal gene transfer studies point toward a strong selection pressure favoring independent evolution of the IBPs in some polar organisms including prokaryotes as well as eukaryotes because these proteins facilitate the polar organisms to acclimatize to the adversities in their niche, thus safeguarding their existence.

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

    NASA Astrophysics Data System (ADS)

    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

  2. Structural characterization of the core region from the lipopolysaccharide of the haloalkaliphilic bacterium Halomonas alkaliantarctica strain CRSS.

    PubMed

    Pieretti, Giuseppina; Carillo, Sara; Nicolaus, Barbara; Poli, Annarita; Lanzetta, Rosa; Parrilli, Michelangelo; Corsaro, Maria Michela

    2010-12-07

    Halophilic and halotolerant Gram-negative bacteria are microorganisms which thrive in high salt environments. LPS are the major components of their outer leaflet, nevertheless very little is known about the role of this molecules in the adaptation mechanisms of extremophiles. Recently we determined the O-chain repeating unit structure of the LPS from Halomonas alkaliantarctica strain CRSS, an haloalkaliphilic Gram-negative bacterium isolated from salt sediments of a saline lake in Cape Russell in Antarctic continent. The polysaccharide is constituted of the trisaccharidic repeating unit: →3)-β-l-Rhap-(1→4)-α-l-Rhap-(1→3)-α-l-Rhap-(1→. In this paper we report the complete core LPS structure from this bacterium. The LPS was hydrolyzed both under mild acid and strong alkaline conditions. The MALDI spectra showed the presence of two glycoforms. The most abundant was recovered after HPAEC purification of the alkaline hydrolyzed product and was characterized by means of 2D-NMR spectroscopy. A comparison of the MALDI-PSD spectra of the two glycoforms suggested that the branched heptose was not stoichiometrically substituted.

  3. The impacts of local human activities on the Antarctic environment

    NASA Astrophysics Data System (ADS)

    Tin, T.; Fleming, Z. L.; Hughes, K. A.; Ainley, D. G.; Convey, P.; Moreno, C. A.; Pfeiffer, S.; Scott, J.; Snape, I.

    2009-04-01

    An overview of a recently published review of the scientific literature from the past decade on the impacts of human activities on the Antarctic environment is presented. An assessment of the cumulative effects of scientists and accompanying base construction, tourists and fishery activities in Antarctica is timely given a decade since the Protocol on Environmental Protection to the Antarctic Treaty came into force in 1998 and the increasing attention given to and human presence in Antarctica during this 2007-2009 IPY. A range of impacts has been identified at a variety of spatial and temporal scales. Chemical contamination and sewage disposal on the continent have been found to be long-lived, with contemporary sewage management practices at many coastal stations insufficient to prevent local contamination. Human activities, particularly construction and transport, have affected Antarctic flora and fauna and a small number of non-indigenous plant and animal species has become established on some of the Antarctic Peninsula and sub Antarctic islands. There is little indication of recovery of overexploited fish stocks, and ramifications of fishing activity on bycatch species and the ecosystem could also be far-reaching. The Antarctic Treaty System and its instruments, in particular the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) and the Environmental Protocol, provide a framework within which management of human activities take place. In order to ensure comprehensive protection of the Antarctic environment, including its intrinsic, wilderness and scientific values in the face of the continuing expansion of human activities in Antarctica, a more effective implementation of a wide range of measures is essential. These include effective environmental impact assessments, long-term monitoring, mitigation measures for non-indigenous species, ecosystem-based management of living resources, and increased regulation of National Antarctic

  4. Bioactive volatile organic compounds from Antarctic (sponges) bacteria.

    PubMed

    Papaleo, Maria Cristiana; Romoli, Riccardo; Bartolucci, Gianluca; Maida, Isabel; Perrin, Elena; Fondi, Marco; Orlandini, Valerio; Mengoni, Alessio; Emiliani, Giovanni; Tutino, Maria Luisa; Parrilli, Ermenegilda; de Pascale, Donatella; Michaud, Luigi; Lo Giudice, Angelina; Fani, Renato

    2013-09-25

    Antarctic bacteria represent a reservoir of unexplored biodiversity, which, in turn, might be correlated to the synthesis of still undescribed bioactive molecules, such as antibiotics. In this work we have further characterized a panel of four marine Antarctic bacteria able to inhibit the growth of human opportunistic multiresistant pathogenic bacteria belonging to the Burkholderia cepacia complex (responsible for the 'cepacia' syndrome in Cystic Fibrosis patients) through the production of a set of microbial Volatile Organic Compounds (mVOCs). A list of 30 different mVOCs synthesized under aerobic conditions by Antarctic bacteria was identified by GC-SPME analysis. Cross-streaking experiments suggested that Antarctic bacteria might also synthesize non-volatile molecules able to enhance the anti-Burkholderia activity. The biosynthesis of such a mixture of mVOCs was very probably influenced by both the presence/absence of oxygen and the composition of media used to grow the Antarctic strains. The antimicrobial activity exhibited by Antarctic strains also appeared to be more related to their taxonomical position rather than to the sampling site. Different Bcc bacteria were differently sensitive to the 'Antarctic' mVOCs and this was apparently related neither to the taxonomical position of the different strains nor to their source. The genome sequence of three new Antarctic strains was determined revealing that only P. atlantica TB41 possesses some genes belonging to the nrps-pks cluster. The comparative genomic analysis performed on the genome of the four strains also revealed the presence of a few genes belonging to the core genome and involved in the secondary metabolites biosynthesis. Data obtained suggest that the antimicrobial activity exhibited by Antarctic bacteria might rely on a (complex) mixture of mVOCs whose relative concentration may vary depending on the growth conditions. Besides, it is also possible that the biosynthesis of these compounds might occur

  5. Antarctic Treaty Summit to Focus on Global Science Policy Lessons

    NASA Astrophysics Data System (ADS)

    Berkman, Paul Arthur; Walton, David W. H.; Weiler, C. Susan

    2008-10-01

    The Antarctic Treaty Summit, which will coincide with the fiftieth anniversary of the treaty's signing, will be held at the Smithsonian Institution's National Museum of Natural History, in Washington, D. C., from 30 November to 3 December 2009. The summit will provide an open international forum for scientists, legislators, lawyers, administrators, educators, students, corporate executives, historians, and other members of global civil society to explore science policy achievements from the first 50 years of the Antarctic Treaty. In addition, the summit will complement official government celebrations of the Antarctic Treaty anniversary that do not include public participation.

  6. Niche-dependent genetic diversity in Antarctic metaviromes

    PubMed Central

    Zablocki, Olivier; van Zyl, Lonnie; Adriaenssens, Evelien M; Rubagotti, Enrico; Tuffin, Marla; Cary, Stephen C; Cowan, Don

    2014-01-01

    The metaviromes from 2 different Antarctic terrestrial soil niches have been analyzed. Both hypoliths (microbial assemblages beneath transluscent rocks) and surrounding open soils showed a high level diversity of tailed phages, viruses of algae and amoeba, and virophage sequences. Comparisons of other global metaviromes with the Antarctic libraries showed a niche-dependent clustering pattern, unrelated to the geographical origin of a given metavirome. Within the Antarctic open soil metavirome, a putative circularly permuted, ∼42kb dsDNA virus genome was annotated, showing features of a temperate phage possessing a variety of conserved protein domains with no significant taxonomic affiliations in current databases. PMID:26458512

  7. Terrestrial ages of Antarctic meteorites: Implications for concentration mechanisms

    NASA Technical Reports Server (NTRS)

    Schultz, L.

    1986-01-01

    Antarctic meteorites differ from meteorites fallen in other places in their mean terrestrial ages. Boeckl estimated the terrestrial half-life for the disintegration of stone meteorites by weathering under the climatic conditions of the Western United States to be about 3600 years. Antarctic meteorites, however, have terrestrial ages up to 70000 years, indicating larger weathering half-lives. The terrestrial ages of meteorites are determined by their concentration of cosmic-ray-produced radionuclides with suitable half-lives (C-14, Al-26, and Cl-36). These radionuclides have yielded reliable ages for the Antarctic meteorites. The distribution of terrestrial ages of Allan Hills and Yamato meteorites are examined.

  8. Niche-dependent genetic diversity in Antarctic metaviromes.

    PubMed

    Zablocki, Olivier; van Zyl, Lonnie; Adriaenssens, Evelien M; Rubagotti, Enrico; Tuffin, Marla; Cary, Stephen C; Cowan, Don

    The metaviromes from 2 different Antarctic terrestrial soil niches have been analyzed. Both hypoliths (microbial assemblages beneath transluscent rocks) and surrounding open soils showed a high level diversity of tailed phages, viruses of algae and amoeba, and virophage sequences. Comparisons of other global metaviromes with the Antarctic libraries showed a niche-dependent clustering pattern, unrelated to the geographical origin of a given metavirome. Within the Antarctic open soil metavirome, a putative circularly permuted, ∼42kb dsDNA virus genome was annotated, showing features of a temperate phage possessing a variety of conserved protein domains with no significant taxonomic affiliations in current databases.

  9. Measurements of Cl-36 in Antarctic meteorites and Antarctic ice using a Van de Graaff accelerator

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Arnold, J. R.; Finkel, R. C.; Elmore, D.; Ferraro, R. D.; Gove, H. E.; Beukens, R. P.; Chang, K. H.; Kilius, L. R.

    1979-01-01

    The paper presents measurements of cosmic-ray produced (Cl-36) in Antarctic meteorites and ice using a Van de Graaff accelerator as an ultrasensitive mass spectrometer. Results from this ion counting technique are used to support a two-stage irradiation model for the Yamato-7301 and Allan Hills-76008 meteorites and to show a long terrestrial age for Allan Hills-77002. Yamato-7304 has a terrestrial age of less than 0.1 m.y., and the (Cl-36) content of the Antarctic ice sample from the Yamato mountain is consistent with levels expected in currently depositing snow implying that the age of the ice cap at this site is less than on (Cl-36) half-life.

  10. Influence of West Antarctic Ice Sheet collapse on Antarctic surface climate

    NASA Astrophysics Data System (ADS)

    Steig, Eric J.; Huybers, Kathleen; Singh, Hansi A.; Steiger, Nathan J.; Ding, Qinghua; Frierson, Dargan M. W.; Popp, Trevor; White, James W. C.

    2015-06-01

    Climate model simulations are used to examine the impact of a collapse of the West Antarctic Ice Sheet (WAIS) on the surface climate of Antarctica. The lowered topography following WAIS collapse produces anomalous cyclonic circulation with increased flow of warm, maritime air toward the South Pole and cold-air advection from the East Antarctic plateau toward the Ross Sea and Marie Byrd Land, West Antarctica. Relative to the background climate, areas in East Antarctica that are adjacent to the WAIS warm, while substantial cooling (several °C) occurs over parts of West Antarctica. Anomalously low isotope-paleotemperature values at Mount Moulton, West Antarctica, compared with ice core records in East Antarctica, are consistent with collapse of the WAIS during the last interglacial period, Marine Isotope Stage 5e. More definitive evidence might be recoverable from an ice core record at Hercules Dome, East Antarctica, which would experience significant warming and positive oxygen isotope anomalies if the WAIS collapsed.

  11. Draft Genome Sequence of the Suttonella ornithocola Bacterium

    PubMed Central

    Waldman Ben-Asher, Hiba; Yerushalmi, Rebecca; Wachtel, Chaim; Barbiro-Michaely, Efrat

    2017-01-01

    ABSTRACT   We report here the draft genome sequence of the Suttonella ornithocola bacterium. To date, this bacterium, found in birds, passed only phylogenetic and phenotypic analyses. To our knowledge, this is the first publication of the Suttonella ornithocola genome sequence. The genetic profile provides a basis for further analysis of its infection pathways. PMID:28209820

  12. Catechol siderophore excretion by magnetotactic bacterium Magnetospirillum magneticum AMB-1.

    PubMed

    Calugay, Ronie J; Takeyama, Haruko; Mukoyama, Daikichi; Fukuda, Yorikane; Suzuki, Takeyuki; Kanoh, Kaneo; Matsunaga, Tadashi

    2006-05-01

    Siderophore activity was detected in the culture supernatant of the magnetotactic bacterium Magnetospirillum magneticum AMB-1. Here we report the first structural elucidation of a siderophore produced by a magnetotactic bacterium. The structure of the purified compound was 3,4-dihydroxybenzoic acid as determined by nuclear magnetic resonance (NMR) and electro-spray ionization mass spectroscopy (ESI-MS).

  13. Different adaptations of Chinese winter-over expeditioners during prolonged Antarctic and sub-Antarctic residence

    NASA Astrophysics Data System (ADS)

    Chen, Nan; Wu, Quan; Li, Hao; Zhang, Tao; Xu, Chengli

    2016-05-01

    Prolonged residence in Antarctica is characterized by exposure to isolated, confined, and extreme (ICE) environment. Winter-over expeditioners at research stations often exhibit a complex of psychophysiological symptoms, which varied by stations and sociocultural backgrounds. To understand the different patterns of psychophysiological responses provoked by environmental stress, we conducted a longitudinal assessment of mood and endocrine function in two groups of Chinese expeditioners who were deployed to sub-Antarctic (Great Wall Station, 62°S, N = 12) and Antarctic (Zhongshan Station, 66°S, N = 16) from December 2003 to 2005. Measures of mood, thyroid function, the levels of plasma catecholamine, and circulating interleukins were obtained at departure from China, mid-winter (Antarctica), end of winter (Antarctica), and return to China, respectively. The Zhongshan Station crew experienced significant increases in fatigue, anger, tension, confusion, and decrease in free thyroxine (FT4), norepinephrine (NE), and epinephrine (E) during the winter, increase in thyrotropin (TSH) and total triiodothyronine (TT3) when returning, whereas their counterparts at Great Wall Station only experienced increased TT3 after deployment. Moreover, compared with the Great Wall Station crew, the Zhongshan Station crew exhibited greater increase in anger, greater decrease in FT4, total thyroxine (TT4), NE and E over the winter, and greater increase in TSH when returning. Chinese expeditioners who lived and worked at the Antarctic station and the sub-Antarctic station for over a year showed different change patterns in mood and endocrine hormones. Negative mood and endocrine dysfunction were positively associated with the severity of environment. The study is a supplement to scientific knowledge on psychophysiological variation under ICE environment, which has certain applied value for the development of preventive countermeasures or interventions.

  14. Antarctic meteorite newsletter. Volume 4: Number 1, February 1981: Antarctic meteorite descriptions, 1976, 1977, 1978, 1979

    NASA Technical Reports Server (NTRS)

    Stone, R.; Schwarz, C. M.; King, T. V. V.; Mason, B.; Bogard, D. D.; Gabel, E. M.

    1981-01-01

    This issue of the Newsletter is essentially a catalog of all antarctic meteorites in the collections of the Johnson Space Center Curation Facility and the Smithsonian except for 288 pebbles now being classed. It includes listings of all previously distributed data sheets plus a number of new ones for 1979. Indexes of samples include meteorite name/number, classification, and weathering category. Separate indexes list type 3 and 4 chondrites, all irons, all achondrites, and all carbonaceous chondrites.

  15. Different adaptations of Chinese winter-over expeditioners during prolonged Antarctic and sub-Antarctic residence.

    PubMed

    Chen, Nan; Wu, Quan; Li, Hao; Zhang, Tao; Xu, Chengli

    2016-05-01

    Prolonged residence in Antarctica is characterized by exposure to isolated, confined, and extreme (ICE) environment. Winter-over expeditioners at research stations often exhibit a complex of psychophysiological symptoms, which varied by stations and sociocultural backgrounds. To understand the different patterns of psychophysiological responses provoked by environmental stress, we conducted a longitudinal assessment of mood and endocrine function in two groups of Chinese expeditioners who were deployed to sub-Antarctic (Great Wall Station, 62°S, N = 12) and Antarctic (Zhongshan Station, 66°S, N = 16) from December 2003 to 2005. Measures of mood, thyroid function, the levels of plasma catecholamine, and circulating interleukins were obtained at departure from China, mid-winter (Antarctica), end of winter (Antarctica), and return to China, respectively. The Zhongshan Station crew experienced significant increases in fatigue, anger, tension, confusion, and decrease in free thyroxine (FT4), norepinephrine (NE), and epinephrine (E) during the winter, increase in thyrotropin (TSH) and total triiodothyronine (TT3) when returning, whereas their counterparts at Great Wall Station only experienced increased TT3 after deployment. Moreover, compared with the Great Wall Station crew, the Zhongshan Station crew exhibited greater increase in anger, greater decrease in FT4, total thyroxine (TT4), NE and E over the winter, and greater increase in TSH when returning. Chinese expeditioners who lived and worked at the Antarctic station and the sub-Antarctic station for over a year showed different change patterns in mood and endocrine hormones. Negative mood and endocrine dysfunction were positively associated with the severity of environment. The study is a supplement to scientific knowledge on psychophysiological variation under ICE environment, which has certain applied value for the development of preventive countermeasures or interventions.

  16. The influence of Antarctic ice sheet topography change on Antarctic climate -- a positive feedback.

    NASA Astrophysics Data System (ADS)

    Steig, E. J.

    2015-12-01

    The potential for climate change to result in changes to the Antarctic ice sheet -- including the possibility of a full collapse of the West Antarctic Ice Shet (WAIS) is well known. Less well known is that the collapse of the ice sheet, if it occured, would have significant impcts on regional climate. We use climate model simulations to quantify the impact of topographic changes on the surface climate of Antarctica. As a general rule, lowered topography produces anomalous cyclonic circulation owing to fundamental atmospheric dynamical constraints. In the case of WAIS collapse, this causes increased flow of warm, maritime air toward the South Pole and cold-air advection from the East Antarctic plateau toward the Ross Sea and Marie Byrd Land, West Antarctica. This resulting pattern The result is cooling in some areas and warming in others, a pattern that is similar to that observed from ice core paleotemperature data for the last interglacial period, suggesting that WAIS collapse occurred at that time. We find that magnitude of the response is roughly linear with the magnitude of the imposed elevation change. The regional response over West Antarctica is large enough that it probably needs to be taken into account in modeling future changes to the ice sheet. Of particular interest is that lowering of the WAIS topography results in anomalous westerlies along the Amundsen Sea coastline. Anomalous westerlies in this region today are in large part responsible for the for intrusion of circumpolar deepwater onto the continental shelf, and the observed rapid thinning of West Antarctic ice shelves. A positive feedback may thus exist in which lowering of the WAIS surface from climate forcing may enhance that forcing, leading to further elevation lowering and ice sheet mass loss.

  17. Tropical pacing of Antarctic sea ice increase

    NASA Astrophysics Data System (ADS)

    Schneider, D. P.

    2015-12-01

    One reason why coupled climate model simulations generally do not reproduce the observed increase in Antarctic sea ice extent may be that their internally generated climate variability does not sync with the observed phases of phenomena like the Pacific Decadal Oscillation (PDO) and ENSO. For example, it is unlikely for a free-running coupled model simulation to capture the shift of the PDO from its positive to negative phase during 1998, and the subsequent ~15 year duration of the negative PDO phase. In previously presented work based on atmospheric models forced by observed tropical SSTs and stratospheric ozone, we demonstrated that tropical variability is key to explaining the wind trends over the Southern Ocean during the past ~35 years, particularly in the Ross, Amundsen and Bellingshausen Seas, the regions of the largest trends in sea ice extent and ice season duration. Here, we extend this idea to coupled model simulations with the Community Earth System Model (CESM) in which the evolution of SST anomalies in the central and eastern tropical Pacific is constrained to match the observations. This ensemble of 10 "tropical pacemaker" simulations shows a more realistic evolution of Antarctic sea ice anomalies than does its unconstrained counterpart, the CESM Large Ensemble (both sets of runs include stratospheric ozone depletion and other time-dependent radiative forcings). In particular, the pacemaker runs show that increased sea ice in the eastern Ross Sea is associated with a deeper Amundsen Sea Low (ASL) and stronger westerlies over the south Pacific. These circulation patterns in turn are linked with the negative phase of the PDO, characterized by negative SST anomalies in the central and eastern Pacific. The timing of tropical decadal variability with respect to ozone depletion further suggests a strong role for tropical variability in the recent acceleration of the Antarctic sea ice trend, as ozone depletion stabilized by late 1990s, prior to the most

  18. Antarctic Ice Sheet fertilises the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Wadham, J. L.; Death, R.; Monteiro, F. M.; Le Brocq, A. M.; Tranter, M.; Ridgwell, A. J.; Raiswell, R.; Hawkings, J.

    2012-12-01

    Southern Ocean (SO) marine primary productivity (PP) is limited by the availability of iron in surface waters, such that variations in iron supply to the SO are thought to exert a major control upon atmospheric CO2 concentrations on glacial/interglacial timescales. The zone bordering the Antarctic Ice Sheet exhibits high PP, exhibiting seasonal plankton blooms in response to elevated dissolved iron concentrations. The source of iron stimulating these PP increases is in debate, traditionally ascribed contributors being aeolian dust, coastal sediments/upwelling and sea ice. More recently, icebergs and glacial meltwater have been suggested as sources. Data from glacial meltwaters worldwide indicate that sub-Antarctic meltwaters are likely to be anoxic, as a result of long flow paths and little surface input of oxygenated meltwaters. Hence, it is probable that they are rich in dissolved iron (as Fe(II)), acquired via the oxidation of sulphide minerals in sediments. In contrast, iron in iceberg rafted debris is dominated by iron oxyhydroxides, generated in oxic sectors of the ice sheet bed by regelation processes or entrained in icebergs as they pass over shelf sediments. The potential for iron from both these ice sheet sources to impact PP has not yet been quantified. Here we apply the MIT marine ecosystem model to determine the potential impact of ice sheet iron export on SO PP. Fluxes of iceberg and meltwater-derived iron are focused along major ice stream corridors, and enhance iron concentrations in surface ocean waters. The impact on SO PP is greatest in coastal regions, including the Ross Sea, Weddell Sea and Amundsen Sea, all of which are areas of high observed marine PP. Inclusion of ice sheet iron sources in modelled scenarios raises SO PP by 10-30%, and provides a plausible explanation for very high seasonally observed PP around the coastal zone. These results highlight Antarctic runoff and icebergs as previously neglected sources of bioavailable iron to the

  19. Agrobacterium tumefaciens is a diazotrophic bacterium

    SciTech Connect

    Kanvinde, L.; Sastry, G.R.K. )

    1990-07-01

    This is the first report that Agrobacterium tumefaciens can fix nitrogen in a free-living condition as shown by its abilities to grown on nitrogen-free medium, reduce acetylene to ethylene, and incorporate {sup 15}N supplied as {sup 15}N{sub 2}. As with most other well-characterized diazotrophic bacteria, the presence of NH{sub 4}{sup +} in the medium and aerobic conditions repress nitrogen fixation by A. tumefaciens. The system requires molybdenum. No evidence for nodulation was found with pea, peanut, or soybean plants. Further understanding of the nitrogen-fixing ability of this bacterium, which has always been considered a pathogen, should cast new light on the evolution of a pathogenic versus symbiotic relationship.

  20. The chemical formula of a magnetotactic bacterium.

    PubMed

    Naresh, Mohit; Das, Sayoni; Mishra, Prashant; Mittal, Aditya

    2012-05-01

    Elucidation of the chemical logic of life is one of the grand challenges in biology, and essential to the progress of the upcoming field of synthetic biology. Treatment of microbial cells explicitly as a "chemical" species in controlled reaction (growth) environments has allowed fascinating discoveries of elemental formulae of a few species that have guided the modern views on compositions of a living cell. Application of mass and energy balances on living cells has proved to be useful in modeling of bioengineering systems, particularly in deriving optimized media compositions for growing microorganisms to maximize yields of desired bio-derived products by regulating intra-cellular metabolic networks. In this work, application of elemental mass balance during growth of Magnetospirillum gryphiswaldense in bioreactors has resulted in the discovery of the chemical formula of the magnetotactic bacterium. By developing a stoichiometric equation characterizing the formation of a magnetotactic bacterial cell, coupled with rigorous experimental measurements and robust calculations, we report the elemental formula of M. gryphiswaldense cell as CH(2.06)O(0.13)N(0.28)Fe(1.74×10(-3)). Remarkably, we find that iron metabolism during growth of this magnetotactic bacterium is much more correlated individually with carbon and nitrogen, compared to carbon and nitrogen with each other, indicating that iron serves more as a nutrient during bacterial growth rather than just a mineral. Magnetotactic bacteria have not only invoked some interest in the field of astrobiology for the last two decades, but are also prokaryotes having the unique ability of synthesizing membrane bound intracellular organelles. Our findings on these unique prokaryotes are a strong addition to the limited repertoire, of elemental compositions of living cells, aimed at exploring the chemical logic of life. Copyright © 2011 Wiley Periodicals, Inc.

  1. Depletion in Antarctic Ozone and Associated Climatic Change,

    DTIC Science & Technology

    ANTARCTIC REGIONS, *CLIMATE, *DEPLETION, *OZONE, AGREEMENTS, ATMOSPHERES, ATMOSPHERICS, CARBON, CARBON DIOXIDE, COMPUTATIONS, DIOXIDES, GREENHOUSE ... EFFECT , GREENHOUSES, HIGH LATITUDES, LATITUDE, LOSSES, MEAN, METHANE, MODELS, NETS, NITROUS OXIDE, OBSERVATION, OXIDES, PERTURBATIONS, REGIONS, STEADY

  2. Ice sheets. Volume loss from Antarctic ice shelves is accelerating.

    PubMed

    Paolo, Fernando S; Fricker, Helen A; Padman, Laurie

    2015-04-17

    The floating ice shelves surrounding the Antarctic Ice Sheet restrain the grounded ice-sheet flow. Thinning of an ice shelf reduces this effect, leading to an increase in ice discharge to the ocean. Using 18 years of continuous satellite radar altimeter observations, we have computed decadal-scale changes in ice-shelf thickness around the Antarctic continent. Overall, average ice-shelf volume change accelerated from negligible loss at 25 ± 64 cubic kilometers per year for 1994-2003 to rapid loss of 310 ± 74 cubic kilometers per year for 2003-2012. West Antarctic losses increased by ~70% in the past decade, and earlier volume gain by East Antarctic ice shelves ceased. In the Amundsen and Bellingshausen regions, some ice shelves have lost up to 18% of their thickness in less than two decades.

  3. Amino Acids in the Antarctic Martian Meteorite MIL03346

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Aubrey, A.; Dworkin, J. P.; Botta, O.; Bada, J. L.

    2005-01-01

    The report by McKay et al. that the Martian meteorite ALH84001 contains evidence for life on Mars remains controversial. Of central importance is whether ALH84001 and other Antarctic Martian meteorites contain endogenous organic compounds. In any investigation of organic compounds possibly derived from Mars it is important to focus on compounds that play an essential role in biochemistry as we know it and that have properties such as chirality which can be used to distinguish between biotic versus abiotic origins. Amino acids are one of the few compounds that fulfill these requirements. Previous analyses of the Antarctic Martian meteorites ALH84001 and EETA79001 have shown that these meteorites contain low levels of terrestrial amino acid contamination derived from Antarctic ice meltwater. Here we report preliminary amino acid investigations of a third Antarctic Martian meteorite MIL03346 which was discovered in Antarctica during the 2003-04 ANSMET season. Additional information is included in the original extended abstract

  4. West antarctic ice sheet collapse: Chimera or clear danger

    SciTech Connect

    Alley, R.B. ); MacAyeal, D.R. )

    1993-01-01

    The specter of a west antarctic collapse has been with us for 25 years. Recently, certain official assessments concerned primarily with the future response to projected global warming have concluded that Antarctica will not cause much sea-level rise within the planning horizon of a century or so. At the same time startling new results on ice sheet (in)stability have been emerging, pointing to less stability then previously believed. Some recent results are reviewed briefly: Heinrich layers in the North Atlantic show basally lubricated surges of the Laurentide ice sheet; the west antarctic ice sheet collapsed recently; the modern west antarctic ice sheet is changing rapidly locally; the bed of ice stream B is exceptionally well lubricated by water and water-saturated soft sediments; the modern ice sheet is thinning slowly on average; a model west antarctic ice sheet undergoes rapid collapses long after forcing and probably related to penetration of warmth to the bed. 23 refs.

  5. Rayleigh-wave group velocity distribution in the Antarctic region

    NASA Astrophysics Data System (ADS)

    Kobayashi, Reiji; Zhao, Dapeng

    2004-03-01

    We determined 2D group velocity distribution of Rayleigh waves at periods of 20-150 s in the Antarctic region using a tomographic inversion technique. The data are recorded by both permanent networks and temporary arrays. In East Antarctica the velocities are high at periods of 90-150 s, suggesting that the root of East Antarctica is very deep. The velocities in West Antarctica are low at all periods, which may be related to the volcanic activity and the West Antarctic Rift System. Low velocity anomalies appear at periods of 40-140 s along the Southeastern Indian Ridge and the western part of the Pacific Antarctic Ridge. The velocities are only slightly low around the Atlantic Indian Ridge, Southwestern Indian Ridge, and the eastern part of the Pacific Antarctic Ridge, where the spreading rates are small. Around two hotspots, the Mount Erebus and Balleny Islands, the velocity is low at periods of 50-150 s.

  6. The Microphysics of Antarctic Clouds - Part one Observations.

    NASA Astrophysics Data System (ADS)

    Lachlan-Cope, Tom; Listowski, Constantino; O'Shea, Sebastian; Bower, Keith

    2016-04-01

    During the Antarctic summer of 2010 and 2011 in-situ measurements of clouds were made over the Antarctic Peninsula and in 2015 similar measurements were made over the eastern Weddell Sea using the British Antarctic Surveys instrumented Twin Otter aircraft. This paper contrasts the clouds found on either side of the Antarctic Peninsula with the clouds over the eastern Weddell Sea, paying particular attention to the total number of ice and water particles found in the clouds. The differences found between the clouds are considered in relation to the sources of cloud condensation nuclei and ice nuclei that are expected to be active in the different cases. In particular it was found that the number of ice nuclei was very low over the Weddell Sea when compared to other regions.

  7. IceBridge Kicks off Antarctic 2010 Campaign

    NASA Image and Video Library

    On October 18th, NASA's Operation IceBridge scientists and the DC-8 crew departed for Punta Arenas, Chile, where they will begin the Antarctic 2010 phase of the mission. For the next five weeks, in...

  8. German Antarctic Receiving Station (GARS) O'Higgins

    NASA Technical Reports Server (NTRS)

    Neidhardt, Alexander; Ploetz, Christian; Kluegel, Thomas

    2013-01-01

    In 2012, the German Antarctic Receiving Station (GARS) O'Higgins contributed to the IVS observing program with four observation sessions. Maintenance and upgrades were made, and a new replacement dewar is under construction in the observatory at Yebes, Spain.

  9. Reassessing the Organic Content of Antarctic Ice and Meteorites

    NASA Astrophysics Data System (ADS)

    Botta, O.; Martins, Z.; Emmenegger, C.; Dworkin, J. P.; Glavin, D. P.; Harvey, R. P.; Zenobi, R.; Bada, J. L.; Ehrenfreund, P.

    2006-03-01

    Meteorites and Antarctic ice samples collected at the same time and location were analyzed for their PAH and amino acid composition using L2MS and HPLC, respectively. Very low levels of these compounds were found.

  10. Amino Acids in the Antarctic CM Meteorite LEW 90500

    NASA Astrophysics Data System (ADS)

    Botta, O.; Bada, J. L.

    2002-03-01

    The amino acid composition of the Antarctic CM meteorite LEW90500 was determined and compared to that of the CMs Murchison and Murray. The compositional similarity suggest that these meteorites probably originated from the same parent body.

  11. An Antarctic molluscan biomineralisation tool-kit

    NASA Astrophysics Data System (ADS)

    Sleight, Victoria A.; Marie, Benjamin; Jackson, Daniel J.; Dyrynda, Elisabeth A.; Marie, Arul; Clark, Melody S.

    2016-11-01

    The Antarctic clam Laternula elliptica lives almost permanently below 0 °C and therefore is a valuable and tractable model to study the mechanisms of biomineralisation in cold water. The present study employed a multidisciplinary approach using histology, immunohistochemistry, electron microscopy, proteomics and gene expression to investigate this process. Thirty seven proteins were identified via proteomic extraction of the nacreous shell layer, including two not previously found in nacre; a novel T-rich Mucin-like protein and a Zinc-dependent metalloprotease. In situ hybridisation of seven candidate biomineralisation genes revealed discrete spatial expression patterns within the mantle tissue, hinting at modular organisation, which is also observed in the mantle tissues of other molluscs. All seven of these biomineralisation candidates displayed evidence of multifunctionality and strong association with vesicles, which are potentially involved in shell secretion in this species.

  12. Halogenating activities detected in Antarctic macroalgae

    SciTech Connect

    Laturnus, F.; Adams, F.C.; Gomez, I.; Mehrtens, G.

    1997-03-01

    Halogenating activities were determined in samples of 18 cultivated species of brown, red and green macroalgae from the Antarctic. Activities for the halogenating organic compounds with bromide, iodide and chloride were found. Investigated red algae (rhodophytes) showed higher brominating and iodinating activities compared to brown (phaeophytes) and green (chlorophytes) algae. The highest brominating and iodinating activities were measured in the red algae Plocamium cartilagineum (1.11 {+-} 0.01 U g{sup -1} wet algal weight and 0.18 U g{sup -1} wet algal weight, respectively) and Myriogramme mangini (3.62 {+-} 0.17 U g{sup -1} wet algal weight and 4.5 U g{sup -1} wet algal weight, respectively). Chlorinating activities were detected in the red alga Plocamium cartilagineum only (0.086 U g{sup -1} wet algal weight). 30 refs., 2 figs., 1 tab.

  13. AVHRR imagery reveals Antarctic ice dynamics

    NASA Technical Reports Server (NTRS)

    Bindschadler, Robert A.; Vornberger, Patricia L.

    1990-01-01

    A portion of AVHRR data taken on December 5, 1987 at 06:15 GMT over a part of Antarctica is used here to show that many of the most significant dynamic features of ice sheets can be identified by a careful examination of AVHRR imagery. The relatively low resolution of this instrument makes it ideal for obtaining a broad view of the ice sheets, while its wide swath allows coverage of areas beyond the reach of high-resolution imagers either currently in orbit or planned. An interpretation is given of the present data, which cover the area of ice streams that drain the interior of the West Antarctic ice sheet into the Ross Ice Shelf.

  14. AVHRR imagery reveals Antarctic ice dynamics

    SciTech Connect

    Bindschadler, R.A.; Vornberger, P.L. STX Corp., Lanham, MD )

    1990-06-01

    A portion of AVHRR data taken on December 5, 1987 at 06:15 GMT over a part of Antarctica is used here to show that many of the most significant dynamic features of ice sheets can be identified by a careful examination of AVHRR imagery. The relatively low resolution of this instrument makes it ideal for obtaining a broad view of the ice sheets, while its wide swath allows coverage of areas beyond the reach of high-resolution imagers either currently in orbit or planned. An interpretation is given of the present data, which cover the area of ice streams that drain the interior of the West Antarctic ice sheet into the Ross Ice Shelf. 21 refs.

  15. Antarctic Meteorite Newsletter, Volume 29, Number 1

    NASA Technical Reports Server (NTRS)

    Satterwhite, Cecilia (Editor); Righter, Kevin (Editor)

    2006-01-01

    This newsletter contains classifications for 597 new meteorites from the 2003 and 2004 ANtarctic Search for METeorites (ANSMET) seasons. They include samples from the Cumulus Hills, Dominion Range, Grosvenor Mountains, LaPaz Icefield, MacAlpine Hills, and the Miller Range. Macroscopic and petrographic descriptions are given for 25 of the new meteorites: 1 acapulcoite/Iodranite, 1 howardite, 1 diogenite, 2 eucrites, 1 enstatite chondrite, four L3 and two H3 chondrites, 2 CM, 3 CK and 1 CV chondrites, three R chondrites, and four impact melt breccias (with affinities for H and L). Likely the most interesting sample announced in this newsletter is LAP04840, with affinity to R chondrites. This meteorite contains approximately 15% horneblende, and has mineral compositional ranges and oxygen isotopic values similar to those of R chondrites. The presence of an apparently hydrous phase in this petrologic grade 6 chondrite is very unusual, and should be of great interest to many meteoriticists.

  16. Bromoalkane production by Antarctic ice algae

    NASA Technical Reports Server (NTRS)

    Sturges, W. T.; Sullivan, C. W.; Schnell, R. C.; Heidt, L. E.; Pollock, W. H.

    1993-01-01

    Ice microalgae, collected from the underside of annual sea ice in McMurdo Sound, Antarctica, were found to contain and release to seawater a number of brominated hydrocarbons. These included bromoform, dibromomethane, mixed bromochloromethanes, and methyl bromide. Atmospheric measurements in the McMurdo Sound vicinity revealed the presence of bromoform and methyl bromide in the lower atmosphere, with lowest concentrations inland, further indicating that biogenic activity in the Sound is a source of organic bromine gases to the Antarctic atmosphere. This may have important implications for boundary layer chemistry in Antarctica. In the Arctic, the presence of bromoform has been linked to loss of surface ozone in the spring. We report here preliminary evidence for similar surface ozone loss at McMurdo Station.

  17. Submesoscale Wrinkles in the Antarctic Circumpolar Current

    NASA Astrophysics Data System (ADS)

    Taylor, J. R.; Adams, K.; Bachman, S.; Hosegood, P. J.; Sallee, J. B.; Stamper, M. A.

    2016-02-01

    Here, we will present new observations and high-resolution numerical simulations of submesoscale features in the Antarctic Circumpolar Current (ACC). Observations were made as part of the SMILES project from April-May 2015 in the Scotia Sea. During the cruise, a northward mesoscale meander of the ACC was sampled at high resolution using towed bodies, surface drifters, microstructure, and dye release. Satellite imagery indicated the presence of submesoscale `wrinkles' along the sharp temperature gradient associated with the ACC. Observations using a moving vessel profiler (MVP) will be shown which reveal rich three-dimensional structure associated with these features. Numerical simulations, initialized with an idealized version of the observed front qualitatively reproduce these features. The numerical simulations allow us to quantify the vertical velocity associated with the submesoscale features, and their interaction with the strong barotropic jet associated with the ACC.

  18. Changes in the West Antarctic ice sheet

    SciTech Connect

    Alley, R.B. ); Whillans, I.M. )

    1991-11-15

    The portion of the West Antarctic ice sheet that flows into the Ross Sea is thinning in some places and thickening in others. These changes are not caused by any current climatic change, but by the combination of a delayed response to the end of the last global glacial cycle and an internal instability. The near-future impact of the ice sheet on global sea level is largely due to processes internal to the movement of the ice sheet, and not so much to the threat of a possible greenhouse warming. Thus the near-term future of the ice sheet is already determined. However, too little of the ice sheet has been surveyed to predict its overall future behavior.

  19. An Antarctic molluscan biomineralisation tool-kit

    PubMed Central

    Sleight, Victoria A.; Marie, Benjamin; Jackson, Daniel J.; Dyrynda, Elisabeth A.; Marie, Arul; Clark, Melody S.

    2016-01-01

    The Antarctic clam Laternula elliptica lives almost permanently below 0 °C and therefore is a valuable and tractable model to study the mechanisms of biomineralisation in cold water. The present study employed a multidisciplinary approach using histology, immunohistochemistry, electron microscopy, proteomics and gene expression to investigate this process. Thirty seven proteins were identified via proteomic extraction of the nacreous shell layer, including two not previously found in nacre; a novel T-rich Mucin-like protein and a Zinc-dependent metalloprotease. In situ hybridisation of seven candidate biomineralisation genes revealed discrete spatial expression patterns within the mantle tissue, hinting at modular organisation, which is also observed in the mantle tissues of other molluscs. All seven of these biomineralisation candidates displayed evidence of multifunctionality and strong association with vesicles, which are potentially involved in shell secretion in this species. PMID:27833129

  20. VIABILITY OF COLIFORM BACTERIA IN ANTARCTIC SOIL

    PubMed Central

    Boyd, William L.; Boyd, Josephine W.

    1963-01-01

    Boyd, William L. (Ohio State University, Columbus) and Josephine W. Boyd. Viability of coliform bacteria in antarctic soil. J. Bacteriol. 85:1121–1123. 1963.—The distribution of coliform bacteria in soils of Ross Island and the nearby mainland was studied. None was found in almost all of the samples collected, including some from the Adelie penguin rookeries at Cape Royds and Cape Crozier and in soil at the McMurdo Base which had been recently contaminated by human sewage. Samples of pony manure left from previous expeditions were also negative, with one exception where Escherichia coli were present. Studies carried out with two freshly isolated human strains of E. coli and the isolate from pony manure showed that the death rate was extremely rapid, although the animal strain was much more resistant to the various factors of the environment causing death. PMID:14044003

  1. Ecdysteroids from the Antarctic tunicate Synoicum adareanum.

    PubMed

    Miyata, Yoshinari; Diyabalanage, Thushara; Amsler, Charles D; McClintock, James B; Valeriote, Frederick A; Baker, Bill J

    2007-12-01

    Five new ecdysteroids, hyousterones A-D (2-5) and abeohyousterone (6), have been isolated from the Antarctic tunicate Synoicum adareanum along with the known ecdysteroid diaulusterol B (1). Hyousterones B (3) and D (5) are unusual ecdysteroids in bearing the 14beta-hydroxyl group, and abeohyousterone incorporates the 13(14-->8) abeo steroid skeleton, reflecting a rearrangement of the steroid C/D ring system. Abeohyousterone has moderate cytotoxicity toward several cancer cell lines. Hyousterones bearing the 14alpha-hydroxy group (2 and 4) were weakly cytotoxic, while the 14beta-hydroxy hyousterones (3 and 5) were devoid of cytotoxicity. The 14beta-hydroxy function may be a thermodynamic pathway to the 13(14-->8) abeo steroid skeleton. Hyousterones, abeohyousterone, and diaulusterol B are the first ecdysteroids reported from tunicates.

  2. Paleoclimate perspectives on Antarctic ice sheet sensitivity

    NASA Astrophysics Data System (ADS)

    Naish, Timothy

    2015-04-01

    Near- and long-term future projections of global mean sea level rise (SLR) are hampered by a lack of understanding of the potential dynamic contribution of the polar ice sheets, and in particular the Antarctic ice sheets. With the completion of the Intergovernmental Panel on Climate Change's Assessment Report a major challenge continues to be placing an upper bound in sea-level projections for 2100 and beyond. The so-called "deterministic" approach which sums observed- and model-projected trends in the known contributions (e.g. ice sheet and glacier surface mass balance, ocean thermal expansion and ground water storage changes) implies a "likely" upper bound of +100cm by 2080-2100. The "semi-empirical" approach which scales past observed sea-level change to mean surface temperature, and uses this relationship to scale future temperature scenarios, predicts a significantly higher upper bound of up to ~2m by 2100. The discrepancy between the two approaches may in part reflect the poorly understood contribution of ice dynamics - that is the rate of flow of ice sheets into the ocean. An ensemble of Antarctic ice sheet models produces highly divergent results for future sea-level projections, primarily because of uncertainties around the mass changes in the East Antarctic Ice Sheet with some models showing increased precipitation driving a positive mass balance overall, even with loss of the marine-based West Antarctic Ice Sheet (WAIS). Current best estimates suggest a 10-20cm dynamic ice sheet contribution by 2100 to global SLR. Of concern is that marine based ice sheets are highly sensitive to increases in ocean temperature at their margins and rapid disintegration may ensue if the ice sheets grounding lines retreat into deep sub-glacial basins. Recent studies show the highest rates of ice sheet thinning and retreat are occurring at locations around the WAIS where the surface ocean has warmed, and that some WAIS loss may now be irreversible. Geological records allow

  3. ELF/VLF Antarctic Research (Invited)

    NASA Astrophysics Data System (ADS)

    Moore, R. C.

    2013-12-01

    The University of Florida presently performs ELF/VLF measurements at Palmer Station, McMurdo Station, and South Pole Station, Antarctica. Research efforts focus on detecting and analyzing lightning-generated ELF/VLF sferics and on the remote sensing of ionospheric disturbances in the Southern hemisphere. The Antarctic ELF/VLF receivers complement a Northern hemisphere ELF/VLF monitoring array. In this paper, we present our latest observational results, including conjugate observations of lightning-induced electron precipitation, solar X-ray flares, and proton injection events. We also present a statistical analysis of lightning-generated Q-bursts and our ongoing efforts to analyze sferics generated by rocket-triggered lightning at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida. An analysis of man-made electromagnetic noise at Arrival Heights, Antarctica is also considered.

  4. Ecology and energetics of two Antarctic sponges.

    PubMed

    Kowalke

    2000-04-26

    Retention efficiencies, pumping and respiration rates of the two Antarctic sponge species Mycale acerata and Isodictya kerguelensis from Potter Cove, King George Island, were measured. None of the species reached a 100% retention efficiency at any given particle size. This is probably due to the sediment-laden environment in which the animals were dwelling. A less efficient retention decreases the risk of the filtering structures being clogged. Both species filter down into the bacterial size range. Pumping rates of the species were 180 ml h(-1) (M. acerata) and 220 ml h(-1) (I. kerguelensis) per g ash free dry mass (T=1 degrees C), being lower than measured in temperate water species. Oxygen consumption was 0.088 ml O(2) h(-1) (M. acerata; T=1.8 degrees C) and 0.035 ml O(2) h(-1) (I. kerguelensis; T=1 degrees C) per g ash free dry mass.

  5. VIABILITY OF COLIFORM BACTERIA IN ANTARCTIC SOIL.

    PubMed

    BOYD, W L; BOYD, J W

    1963-05-01

    Boyd, William L. (Ohio State University, Columbus) and Josephine W. Boyd. Viability of coliform bacteria in antarctic soil. J. Bacteriol. 85:1121-1123. 1963.-The distribution of coliform bacteria in soils of Ross Island and the nearby mainland was studied. None was found in almost all of the samples collected, including some from the Adelie penguin rookeries at Cape Royds and Cape Crozier and in soil at the McMurdo Base which had been recently contaminated by human sewage. Samples of pony manure left from previous expeditions were also negative, with one exception where Escherichia coli were present. Studies carried out with two freshly isolated human strains of E. coli and the isolate from pony manure showed that the death rate was extremely rapid, although the animal strain was much more resistant to the various factors of the environment causing death.

  6. Organic analysis of the Antarctic carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Kotra, R. K.; Shimoyama, A.; Ponnamperuma, C.; Hare, P. E.; Yanai, K.

    1981-01-01

    Thus far, organic analysis of carbonaceous chondrites has proven the only fruitful means of examining complex organic matter of extraterrestrial origin. The present paper presents the results of organic analysis of two Antarctic meteorites, Allan Hills (77306) and Yamato (74662), which may be considered free from terrestrial contamination. Ion-exchange chromatography, gas chromatography and mass spectrometery of meteorite samples reveal the presence in Yamato of 15 and in Allan Hills of 20 protein and nonprotein amino acids, the most abundant of which are glycine and alanine. Abundances of the D and L enantiomers of each amino acid are also found to be nearly equal. Data thus indicate an abiotic extraterrestrial origin for the matter, and confirm a lack of terrestrial contamination.

  7. Joint Antarctic School Expedition - An International Collaboration for High School Students and Teachers on Antarctic Science

    NASA Astrophysics Data System (ADS)

    Botella, J.; Warburton, J.; Bartholow, S.; Reed, L. F.

    2014-12-01

    The Joint Antarctic School Expedition (JASE) is an international collaboration program between high school students and teachers from the United States and Chile aimed at providing the skills required for establishing the scientific international collaborations that our globalized world demands, and to develop a new approach for science education. The National Antarctic Programs of Chile and the United States worked together on a pilot program that brought high school students and teachers from both countries to Punta Arenas, Chile, in February 2014. The goals of this project included strengthening the partnership between the two countries, and building relationships between future generations of scientists, while developing the students' awareness of global scientific issues and expanding their knowledge and interest in Antarctica and polar science. A big component of the project involved the sharing by students of the acquired knowledge and experiences with the general public. JASE is based on the successful Chilean Antarctic Science Fair developed by Chile´s Antarctic Research Institute. For 10 years, small groups of Chilean students, each mentored by a teacher, perform experimental or bibliographical Antarctic research. Winning teams are awarded an expedition to the Chilean research station on King George Island. In 2014, the Chileans invited US participation in this program in order to strengthen science ties for upcoming generations. On King George Island, students have hands-on experiences conducting experiments and learning about field research. While the total number of students directly involved in the program is relatively small, the sharing of the experience by students with the general public is a novel approach to science education. Research experiences for students, like JASE, are important as they influence new direction for students in science learning, science interest, and help increase science knowledge. We will share experiences with the

  8. Functional ecology of an Antarctic Dry Valley

    PubMed Central

    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

  9. Arctic and Antarctic sea ice and climate

    NASA Astrophysics Data System (ADS)

    Barreira, S.

    2014-12-01

    Principal Components Analysis in T-Mode Varimax rotated was performed on Antarctic and Arctic monthly sea ice concentration anomalies (SICA) fields for the period 1979-2014, in order to investigate which are the main spatial characteristics of sea ice and its relationship with atmospheric circulation. This analysis provides 5 patterns of sea ice for inter-spring period and 3 patterns for summer-autumn for Antarctica (69,2% of the total variance) and 3 different patterns for summer-autumn and 3 for winter-spring season for the Arctic Ocean (67,8% of the total variance).Each of these patterns has a positive and negative phase. We used the Monthly Polar Gridded Sea Ice Concentrations database derived from satellite information generated by NASA Team algorithm. To understand the links between the SICA and climate trends, we extracted the mean pressure and, temperature field patterns for the months with high loadings (positive or negative) of the sea ice patterns that gave distinct atmospheric structures associated with each one. For Antarctica, the first SICA spatial winter-spring pattern in positive phase shows a negative SICA centre over the Drake Passage and north region of Bellingshausen and Weddell Seas together with another negative SICA centre over the East Indian Ocean. Strong positive centres over the rest of the Atlantic and Indian Oceans basins and the Amundsen Sea are also presented. A strong negative pressure anomaly covers most of the Antarctic Continent centered over the Bellingshausen Sea accompanied by three positive pressure anomalies in middle-latitudes. During recent years, the Arctic showed persistent associations of sea-ice and climate patterns principally during summer. Our strongest summer-autumn pattern in negative phase showed a marked reduction on SICA over western Arctic, primarily linked to an overall increase in Arctic atmospheric temperature most pronounced over the Beaufort, Chukchi and East Siberian Seas, and a positive anomaly of

  10. Morphogenesis of Antarctic Paleosols: Martian Analogue

    NASA Astrophysics Data System (ADS)

    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

  11. Functional ecology of an Antarctic Dry Valley.

    PubMed

    Chan, Yuki; Van Nostrand, Joy D; Zhou, Jizhong; Pointing, Stephen B; Farrell, Roberta L

    2013-05-28

    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.

  12. Microtubule-associated proteins from Antarctic fishes.

    PubMed

    Detrich, H W; Neighbors, B W; Sloboda, R D; Williams, R C

    1990-01-01

    Microtubules and presumptive microtubule-associated proteins (MAPs) were isolated from the brain tissues of four Antarctic fishes (Notothenia gibberifrons, N. coriiceps neglecta, Chaenocephalus aceratus, and a Chionodraco sp.) by means of a taxol-dependent, microtubule-affinity procedure (cf. Vallee: Journal of Cell Biology 92:435-442, 1982). MAPs from these fishes were similar to each other in electrophoretic pattern. Prominent in each preparation were proteins in the molecular weight ranges 410,000-430,000, 220,000-280,000, 140,000-155,000, 85,000-95,000, 40,000-45,000, and 32,000-34,000. The surfaces of MAP-rich microtubules were decorated by numerous filamentous projections. Exposure to elevated ionic strength released the MAPs from the microtubules and also removed the filamentous projections. Addition of fish MAPs to subcritical concentrations of fish tubulins at 0-5 degrees C induced the assembly of microtubules. Both the rate and the extent of this assembly increased with increasing concentrations of the MAPs. Sedimentation revealed that approximately six proteins, with apparent molecular weights between 60,000 and 300,000, became incorporated into the microtubule polymer. Bovine MAPs promoted microtubule formation by fish tubulin at 2-5 degrees C, and proteins corresponding to MAPs 1 and 2 co-sedimented with the polymer. MAPs from C. aceratus also enhanced the polymerization of bovine tubulin at 33 degrees C, but the microtubules depolymerized at 0 degrees C. We conclude that MAPs are part of the microtubules of Antarctic fishes, that these proteins promote microtubule assembly in much the same way as mammalian MAPs, and that they do not possess special capacities to promote microtubule assembly at low temperatures or to prevent cold-induced microtubule depolymerization.

  13. Active margin processes along the Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Henriet, J. P.; Meissner, R.; Miller, H.; The Grape Team

    1992-01-01

    The Antarctic Peninsula has a remarkable record of active margin processes, which include subduction with progressive ridge-trench collisions, margin segmentation by major fracture zones, rifting in a hybrid back-arc and sheared plate margin context, fore-arc basin development and glacial-marine controlled trench fill processes. Several facets of these active margin processes both of internal (crustal dynamic) and external origin (climate-controlled) have been documented by a geophysical survey during the Antarktis VI/2 cruise of R.V. Polarstem(October-December 1987). Reflection seismic profiles have been shot over the rift basin of Bransfield Strait, over an elongated sediment-filled trough interpreted as a fore-arc basin, over accretional and progradational slopes, over recent and ancient trench environments and over the facing oceanic domain. In this oceanic domain, different fracture zones have highly contrasting morphological and geophysical expressions. The subduction of a fracture zone like Hero F.Z., characterized by a significant relief possibly related to the presence of buoyant (serpentinite) ridges, may have been a factor of subduction termination for the last segment of the Aluk (Drake) plate; it may also have played a role in the separation of a blueschist-bearing fragment (Smith Island) from the base of the accretionary plate margin and in its lift to the surface. The magnetic anomaly pattern of the oceanic slabs facing the northwestern Peninsula margin shows evidence of an intriguing spreading acceleration, which apparently preceded ridge-trench collision. The same anomaly pattern provides a clue to the stratigraphie interpretation of the oceanic sediment cover and of the frontal part of the prograding, now passive margin south of the South Shetland Island Arc. An apparently broken and tilted oceanic plate fragment, squeezed between the South Shetland Trench and Shackleton Fracture Zone, may argue for the role of transpression associated with the

  14. Antarctic mass balance changes from GRACE

    NASA Astrophysics Data System (ADS)

    Kallenberg, B.; Tregoning, P.

    2012-04-01

    The Antarctic ice sheet contains ~30 million km3 of ice and constitutes a significant component of the global water balance with enough freshwater to raise global sea level by ~60 m. Altimetry measurements and climate models suggest variable behaviour across the Antarctic ice sheet, with thickening occurring in a vast area of East Antarctica and substantial thinning in West Antarctica caused by increased temperature gradients in the surrounding ocean. However, the rate at which the polar ice cap is melting is still poorly constrained. To calculate the mass loss of an ice sheet it is necessary to separate present day mass balance changes from glacial isostatic adjustment (GIA), the response of the Earth's crust to mass loss, wherefore it is essential to undertake sufficient geological and geomorphological sampling. As there is only a limited possibility for this in Antarctica, all models (i.e. geological, hydrological as well as atmospheric) are very poorly constrained. Therefore, space-geodetic observations play an important role in detecting changes in mass and spatial variations in the Earth's gravity field. The Gravity Recovery And Climate Experiment (GRACE) observed spatial variations in the Earth's gravity field over the past ten years. The satellite detects mass variations in the Earth system including geophysical, hydrological and atmospheric shifts. GRACE itself is not able to separate the GIA from mass balance changes and, due to the insufficient geological and geomorphological database, it is not possible to model the GIA effect accurately for Antarctica. However, the results from GRACE can be compared with other scientific results, coming from other geodetic observations such as satellite altimetry and GPS or by the use of geological observations. In our contribution we compare the GRACE data with recorded precipitation patterns and mass anomalies over East Antarctica to separate the observed GRACE signal into its two components: GIA as a result of mass

  15. AMICA (Antarctic Multiband Infrared CAmera) project

    NASA Astrophysics Data System (ADS)

    Dolci, Mauro; Straniero, Oscar; Valentini, Gaetano; Di Rico, Gianluca; Ragni, Maurizio; Pelusi, Danilo; Di Varano, Igor; Giuliani, Croce; Di Cianno, Amico; Valentini, Angelo; Corcione, Leonardo; Bortoletto, Favio; D'Alessandro, Maurizio; Bonoli, Carlotta; Giro, Enrico; Fantinel, Daniela; Magrin, Demetrio; Zerbi, Filippo M.; Riva, Alberto; Molinari, Emilio; Conconi, Paolo; De Caprio, Vincenzo; Busso, Maurizio; Tosti, Gino; Nucciarelli, Giuliano; Roncella, Fabio; Abia, Carlos

    2006-06-01

    The Antarctic Plateau offers unique opportunities for ground-based Infrared Astronomy. AMICA (Antarctic Multiband Infrared CAmera) is an instrument designed to perform astronomical imaging from Dome-C in the near- (1 - 5 μm) and mid- (5 - 27 μm) infrared wavelength regions. The camera consists of two channels, equipped with a Raytheon InSb 256 array detector and a DRS MF-128 Si:As IBC array detector, cryocooled at 35 and 7 K respectively. Cryogenic devices will move a filter wheel and a sliding mirror, used to feed alternatively the two detectors. Fast control and readout, synchronized with the chopping secondary mirror of the telescope, will be required because of the large background expected at these wavelengths, especially beyond 10 μm. An environmental control system is needed to ensure the correct start-up, shut-down and housekeeping of the camera. The main technical challenge is represented by the extreme environmental conditions of Dome C (T about -90 °C, p around 640 mbar) and the need for a complete automatization of the overall system. AMICA will be mounted at the Nasmyth focus of the 80 cm IRAIT telescope and will perform survey-mode automatic observations of selected regions of the Southern sky. The first goal will be a direct estimate of the observational quality of this new highly promising site for Infrared Astronomy. In addition, IRAIT, equipped with AMICA, is expected to provide a significant improvement in the knowledge of fundamental astrophysical processes, such as the late stages of stellar evolution (especially AGB and post-AGB stars) and the star formation.

  16. [Temperature range for growth of the Antarctic microorganisms].

    PubMed

    Romanovaskaia, V A; Tashirev, A B; Gladka, G B; Tashireva, A A

    2012-01-01

    The assessment of a temperature range for growth of microorganisms isolated at various temperatures (1-5 degrees C or 30 degrees C) from biotopes of the Antarctic region (soil, grass Deschampcia antarctica, grass Colobanthus, a green moss, crustose black lichens and encrustation biofilm on vertical rocks) is made. From 40 to 70% of the investigated Antarctic microorganisms, irrespective of temperature conditions of their isolation, were capable of growing in a wide temperature range (from 1 degrees C to 30 degrees C), i.e. they are psychrotolerant. In selective conditions (1 degrees C or 5 degrees C) the psychrophilic Antarctic bacteria and yeast are isolated which grew in the range from 1 degrees C to 20 degrees C and did not grow at 30 degrees C. At the same time, among the Antarctic microorganisms isolated in nonselective conditions (at 30 degrees C), almost 50% are capable of growing at the lowest temperature (5 degrees C), and a smaller number of strains--at 1 degrees C. However with a decrease of cultivation temperature the growth lag-phase of the Antarctic bacteria increased. Thus the level of the final biomass of the investigated strains did not depend on cultivation temperature. When comparing the temperature range of growth of the mesophilic Antarctic bacteria and collection strains of the same species isolated more than 10 years ago from the region with a temperate climate, the psychrotolerant forms were also revealed among the latter. So, it is shown that the investigated Antarctic bacteria can exist in the temperature range characteristic of terrestrial biotopes of the Antarctic Region (from 1 degrees C to 10 degrees C).

  17. Antarctic marine biodiversity and deep-sea hydrothermal vents.

    PubMed

    Chown, Steven L

    2012-01-01

    The diversity of many marine benthic groups is unlike that of most other taxa. Rather than declining from the tropics to the poles, much of the benthos shows high diversity in the Southern Ocean. Moreover, many species are unique to the Antarctic region. Recent work has shown that this is also true of the communities of Antarctic deep-sea hydrothermal vents. Vent ecosystems have been documented from many sites across the globe, associated with the thermally and chemically variable habitats found around these, typically high temperature, streams that are rich in reduced compounds and polymetallic sulphides. The animal communities of the East Scotia Ridge vent ecosystems are very different to those elsewhere, though the microbiota, which form the basis of vent food webs, show less differentiation. Much of the biological significance of deep-sea hydrothermal vents lies in their biodiversity, the diverse biochemistry of their bacteria, the remarkable symbioses among many of the marine animals and these bacteria, and the prospects that investigations of these systems hold for understanding the conditions that may have led to the first appearance of life. The discovery of diverse and unusual Antarctic hydrothermal vent ecosystems provides opportunities for new understanding in these fields. Moreover, the Antarctic vents south of 60°S benefit from automatic conservation under the Convention on the Conservation of Antarctic Marine Living Resources and the Antarctic Treaty. Other deep-sea hydrothermal vents located in international waters are not protected and may be threatened by growing interests in deep-sea mining.

  18. The genome of the Antarctic-endemic copepod, Tigriopus kingsejongensis.

    PubMed

    Kang, Seunghyun; Ahn, Do-Hwan; Lee, Jun Hyuck; Lee, Sung Gu; Shin, Seung Chul; Lee, Jungeun; Min, Gi-Sik; Lee, Hyoungseok; Kim, Hyun-Woo; Kim, Sanghee; Park, Hyun

    2017-01-01

    The Antarctic intertidal zone is continuously subjected to extremely fluctuating biotic and abiotic stressors. The West Antarctic Peninsula is the most rapidly warming region on Earth. Organisms living in Antarctic intertidal pools are therefore interesting for research into evolutionary adaptation to extreme environments and the effects of climate change. We report the whole genome sequence of the Antarctic-endemic harpacticoid copepod Tigriopus kingsejongensi . The 37 Gb raw DNA sequence was generated using the Illumina Miseq platform. Libraries were prepared with 65-fold coverage and a total length of 295 Mb. The final assembly consists of 48 368 contigs with an N50 contig length of 17.5 kb, and 27 823 scaffolds with an N50 contig length of 159.2 kb. A total of 12 772 coding genes were inferred using the MAKER annotation pipeline. Comparative genome analysis revealed that T. kingsejongensis -specific genes are enriched in transport and metabolism processes. Furthermore, rapidly evolving genes related to energy metabolism showed positive selection signatures. The T. kingsejongensis genome provides an interesting example of an evolutionary strategy for Antarctic cold adaptation, and offers new genetic insights into Antarctic intertidal biota.

  19. The genome of the Antarctic-endemic copepod, Tigriopus kingsejongensis

    PubMed Central

    Kang, Seunghyun; Ahn, Do-Hwan; Lee, Jun Hyuck; Lee, Sung Gu; Shin, Seung Chul; Lee, Jungeun; Min, Gi-Sik; Lee, Hyoungseok

    2017-01-01

    Abstract Background: The Antarctic intertidal zone is continuously subjected to extremely fluctuating biotic and abiotic stressors. The West Antarctic Peninsula is the most rapidly warming region on Earth. Organisms living in Antarctic intertidal pools are therefore interesting for research into evolutionary adaptation to extreme environments and the effects of climate change. Findings: We report the whole genome sequence of the Antarctic-endemic harpacticoid copepod Tigriopus kingsejongensi. The 37 Gb raw DNA sequence was generated using the Illumina Miseq platform. Libraries were prepared with 65-fold coverage and a total length of 295 Mb. The final assembly consists of 48 368 contigs with an N50 contig length of 17.5 kb, and 27 823 scaffolds with an N50 contig length of 159.2 kb. A total of 12 772 coding genes were inferred using the MAKER annotation pipeline. Comparative genome analysis revealed that T. kingsejongensis-specific genes are enriched in transport and metabolism processes. Furthermore, rapidly evolving genes related to energy metabolism showed positive selection signatures. Conclusions: The T. kingsejongensis genome provides an interesting example of an evolutionary strategy for Antarctic cold adaptation, and offers new genetic insights into Antarctic intertidal biota. PMID:28369352

  20. Development of a Regional Glycerol Dialkyl Glycerol Tetraether (GDGT) - Temperature Calibration for Antarctic and sub-Antarctic Lakes

    NASA Astrophysics Data System (ADS)

    Roberts, S. J.; Foster, L. C.; Pearson, E. J.; Steve, J.; Hodgson, D.; Saunders, K. M.; Verleyen, E.

    2016-12-01

    Temperature calibration models based on the relative abundances of sedimentary glycerol dialkyl glycerol tetraethers (GDGTs) have been used to reconstruct past temperatures in both marine and terrestrial environments, but have not been widely applied in high latitude environments. This is mainly because the performance of GDGT-temperature calibrations at lower temperatures and GDGT provenance in many lacustrine settings remains uncertain. To address these issues, we examined surface sediments from 32 Antarctic, sub-Antarctic and Southern Chilean lakes. First, we quantified GDGT compositions present and then investigated modern-day environmental controls on GDGT composition. GDGTs were found in all 32 lakes studied. Branched GDGTs (brGDGTs) were dominant in 31 lakes and statistical analyses showed that their composition was strongly correlated with mean summer air temperature (MSAT) rather than pH, conductivity or water depth. Second, we developed the first regional brGDGT-temperature calibration for Antarctic and sub-Antarctic lakes based on four brGDGT compounds (GDGT-Ib, GDGT-II, GDGT-III and GDGT-IIIb). Of these, GDGT-IIIb proved particularly important in cold lacustrine environments. Our brGDGT-Antarctic temperature calibration dataset has an improved statistical performance at low temperatures compared to previous global calibrations (r2=0.83, RMSE=1.45°C, RMSEP-LOO=1.68°C, n=36 samples), highlighting the importance of basing palaeotemperature reconstructions on regional GDGT-temperature calibrations, especially if specific compounds lead to improved model performance. Finally, we applied the new Antarctic brGDGT-temperature calibration to two key lake records from the Antarctic Peninsula and South Georgia. In both, downcore temperature reconstructions show similarities to known Holocene warm periods, providing proof of concept for the new Antarctic calibration model.