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Ice cores are drilled from polar glaciers because they are useful for studying past climate and
environment that change through time. We here report on the progress of the first shallow ice-core drilling program
of Korea Polar Research Institute since the establishment of the Antarctic Jang Bogo station, the second Antarctic
research station of Korea. The drilling was performed on the Styx glacier about 85 km north of the Jang Bogo station
in the 2014-2015 summer season, and a 210.5 m long ice core was taken in 300 runs, in 20 days. The age at the
bottom of the ice core was estimated to be 1.36 ka based on the depth-density profile and on the temperature at
15 m depth. The drill was stuck at a depth of 104 m but was recovered by using ethanol. The tephra ash layers
were observed at depths of 97.01, 99.18 and 165.37 m, whose ages were tentatively estimated to be 0.56, 0.57 and
1.04 ka, respectively. Further study should include in-depth work for the tephra layer ages.
Ice krill is the keystone species in the neritic ecosystem in the Southern Ocean, where it replaces the more oceanic Antarctic krill. It is essential to understand the variation of target strength (TS in dB re
1 m 2 ) with the different body size to accurately estimate ice krill stocks. However, there is comparatively little knowledge of the acoustic backscatter of ice krill. The TS of individual, formalin-preserved, tethered
ice krill was measured in a freshwater test tank at 38, 120, and 200 kHz with a calibrated split-beam echo sounder system. Mean TS was obtained from 21 individual ice krill with a broad range of body lengths ( L :
13-36 mm). The length ( L , mm) to wet weight ( W ; mg) relationship for ice krill was W =0.001 218×103 × L 3.53 ( R2 =0.96). The mean TS-to-length relationship were TS 38 kHz =-177.4+57log10 ( L ), ( R2 = 0.86); TS 120 kHz =
-129.9+31.56log 10 ( L ), ( R 2 =0.87); and TS 200 kHz =-117.6+24.66log 10 ( L ), ( R 2 =0.84). Empirical estimates of the relationship between the TS and body length of ice krill were established at 38, 120, and 200 kHz and
compared with predictions obtained from both the linear regression model of Greene et al. (1991) and the Stochastic Distorted Wave Born Approximation (SDWBA) model. This result might be applied to improve
acoustic detection and density estimation of ice krill in the Southern Ocean. Further comparative studies are needed with in situ target strength including various body lengths of ice krill.
Ice-binding proteins (IBPs) inhibit ice growth through direct interaction with ice crystals that permit the survival of polar organisms in extremely cold environments. FfIBP is an ice-binding protein encoded by the Antarctic bacterium Flavobacteriumfrigoris PS1. The X-ray crystal structure of FfIBP was determined to 2.1-A resolution to gain insight into its ice-binding mechanism. The refined structure of FfIBP shows an intramolecular disulfide bond, and analytical ultra-centrifugation and analytical size exclusion chromatography show that it behaves as a monomer in solution. Sequence alignments and structural comparisons of IBPs allowed us to define two groups within IBPs, depending on sequence differences between the α2 and α4 loop regions and the presence of the disulfide bond. Although FfIBP closely resembles Leucosporidium IBP (LeIBP) in its amino acid sequence, the thermal hysteresis (TH) activity of FfIBP appears to be 10-fold higher than that of LeIBP. A comparison of the FfIBP and LeIBP structures reveals that FfIBP has different ice-binding residues as well as greater surface area in the ice-binding site. Notably, the ice-binding site of FfIBP is composed of the T-A/G-X-T/N motif, which is similar to the ice-binding residues of hyperactive antifreeze proteins. Thus, we propose that the TH activity difference between FfIBP and LeIBP may come from the amino acid composition of the ice-binding site, which correlates with differences in affinity and surface complementarity with the ice crystal. In conclusion, this study provides the 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 that of LeIBP.
Ice-binding proteins (IBPs) inhibit ice growth through direct interaction with ice crystals that permit the survival of polar organisms in extremely cold environments. FfIBP is an ice-binding protein encoded by the Antarctic bacterium FlavobacteriumfrigorisPS1. The refined structure of FfIBP shows an intramolecular disulfide bond, and analytical ultra-centrifugation and analytical size exclusion chromatography show that it behaves as a monomer in solution. Sequence alignments and structural comparisons of IBPs allowed us to define two groups within IBPs, depending on sequence differences between the α2 and α4 loop regions and the presence of the disulfide bond. Although FfIBP closely resembles Leucosporidium IBP (LeIBP) in its amino acid sequence, the thermal hysteresis (TH) activity of FfIBP appears to be 10-fold higher than that of LeIBP. A comparison of the FfIBP and LeIBP structures reveals that FfIBP has different ice-binding residues as well as greater surface area in the ice-binding site. Notably, the ice-binding site of FfIBP is composed of the T-X-A/G-T/N motif, which is similar to the ice-binding residues of hyperactive antifreeze proteins. Thus, we propose that the TH activity difference between FfIBP and LeIBP may come from the amino acid composition of the ice-binding site, which correlates with differences in affinity and surface complementarity with the ice crystal.
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 β2 and β4 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 ten-fold 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.
Identifying marine features that support high foraging performance of predators is useful to determine
areas of ecological importance. This study aimed to identify marine features that are important for
foraging of chinstrap penguins (Pygoscelis antarcticus), an abundant upper-trophic level predator in the
Antarctic Peninsula region. We investigated the foraging locations of penguins breeding on King George
Island using GPS-depth loggers. Tracking data from 18 birds (4232 dives), 11 birds (2095 dives), and 19
birds (3947 dives) were obtained in 2007, 2010, and 2015, respectively. In all three years, penguins
frequently visited an area near a seamount (Orca Seamount) in Bransfield Strait. The percentage of dives
(27.8% in 2007, 36.1% in 2010, and 19.1% in 2015) and depth wiggles (27.1% in 2007, 37.2% in 2010, and
22.3% in 2015) performed in this area was higher than that expected from the size of the area and
distance from the colony (8.4% for 2007, 14.7% for 2010, and 6.3% for 2015). Stomach content analysis
showed that the penguins fed mainly on Antarctic krill. These results suggest that the seamount provided
a favorable foraging area for breeding chinstrap penguins, with high availability of Antarctic krill,
possibly related to local upwelling.
In 2013, strong wind was observed more frequently than before at the King Sejong Station located on King George Island, Antarctic Peninsula. We investigated strong blizzard case observed in January 2013 to understand underlying conditions and to tell if it is linked with changing climate in Antarctica. For that purpose, we ran Polar WRF V3.3.1 to simulate weather condition. Polar WRF has reasonably well reproduced the strong wind case. Besides, we found that a blocking system was existed east of south-America. Blocking system in southern hemisphere seems to affect the variation of Antarctic low pressure systems. We speculate that interannual variation of sea ice extent around the Antarctica would be one of important factors influencing pressure systems and blocking system. We will present our model results and linkage with blocking index.
In 2D full waveform inversions of acoustic-elastic coupled media, wave propagation is described by the acoustic and isotropic elastic wave equations. To consider the irregular topography of the seafloor in full waveform inversions, the interface between the acoustic and elastic media in wave propagation modeling by the finite element method is represented using both square and isosceles triangular elements. However, numerical artifacts are generated near the seafloor, and widespread abnormal gradient directions are generated in the high velocity area in the target model, when the gradient direction is calculated during full waveform inversion in the Laplace domain. This issue generates unsuitable inversion results near the seafloor. We propose a scaling function that minimizes numerical artifacts in the gradient direction for Laplace domain full waveform inversion of acoustic-elastic coupled media. Based on a heuristic approach, we describe a gradient scaling method of Laplace-domain waveform inversion in acoustic-elastic coupled media that can be used to construct more accurate P- and S-wave velocity models of geological targets beneath the seafloor than previous methods. The technique scales the gradient direction using an accumulated gradient that is generated from the accumulated sum of the squares of the conventional gradient with respect to depth. This approach is designed to improve the imaging of large anomalies with high-velocity structures and to attenuate artifacts that are related to an irregular seafloor. We perform numerical tests using the synthetic SEG/EAGE salt model and field data. The numerical results demonstrate the validity of Laplace-domain waveform inversions that are calculated with the new scaling method for acoustic-elastic coupled media. The proposed gradient scaling method reduces artifacts more with field data than in the synthetic case. In particular, the abnormal high velocity areas near the seafloor in the inverted P- and S-wave velocity models are effectively removed by the gradient scaling method. We also conduct frequency-domain waveform inversion using the Laplace-domain inversion results as an initial model to confirm the accuracy of the inverted model of field data from our proposed inversion algorithm. The reverse time migration images and synthetic seismograms that were obtained from the field data indicate that this gradient scaling method is a useful tool for building accurate long-wavelength inverted P-and S-wave velocity models of field data from the Laplace domain full waveform inversion.
In Antarctica, the geochemical properties of meltwater and pondwater are very sensitive to global warming. Therefore, understanding the geochemical properties of the meltwater and pondwater is crucial to evaluating global climate
change. This study was performed to examine the chemical and isotopic compositions of the meltwater and pondwater at the Barton and Weaver Peninsulas of King George Island, Antarctica, to understand their spatial variation and to evaluate factors controlling the surface water chemistry. The meltwater, pondwater and seawater were sampled at 50 sites of the Barton and Weaver Peninsulas during the period from 23 December 2010 to 5 January 2011. The chemical compositions of the meltwater and pondwater were mainly influenced by sea salt. Additionally, the influence of water-rock interaction was observed in some meltwater and pondwater. The LREE/HREE ratios of some of the pondwater in the Barton Peninsula showed a decreasing trend by influence of water-rock interaction. The influences of sea salt and water-rock interaction were more dominant at the Barton Peninsula than the Weaver Peninsula. The δ<sup>18</sup>O and δD of the meltwater and
pondwater showed a wide range. Little evaporation losses were observed at the Barton Peninsula but evaporation losses
did not occurred at the Weaver Peninsula.
In December 2011 a new international collaboration was initiated to undertake geoscience and oceanographic studies in the Canadian Arctic. The first of the research which would take place
from 2011 to 2015. We hope to conduct new geological, geophysical and oceanographic investigations of the Beaufort Sea shelf to study the stability of decomposing permafrost and gas
hydrate and the mechanisms for gas migration and release at the sea floor. Our hypothesis is that shelf areas of the Arctic less than 100m water depth, which make up ~32% of the area of the Arctic
Ocean, are underlain by permafrost and gas hydrate stability conditions that formed during past glacial periods and are only now being altered by the thermal effects of marine transgression
which may promote their degradation. Our research will allow assessment of the importance of Arctic shelves as past and present sources of methane for the atmosphere and will quantify a range
of geohazard/environmental processes associated with gas migration and release that have not been documented to date.
The Beaufort Shelf is an ideal study area because:(1) significant amounts of thermally disturbed permafrost gas hydrate are known to exist in the subsurface, (2) gas venting has been documented in association with unique physical features on the sea floor (i.e. active submarine pingo like features, pockmarks, sub-marine slope failures and permafrost taliks), suggesting there are unique point sources and transitional pathways for fluid and gas movements from decomposing gas hydrates, and (3) the surface sediments in this area are predominantly fine-grained, permitting collection of good sediment cores to enable stratigraphic, biostratigraphic and geochemical studies. We believe that research in the Beaufort Sea will contribute to our understanding of other larger Arctic shelves (e.g. the Siberian shelf) and will be greatly valued by the international research community. Both the Integrated Ocean Drilling Program (IODP) and the Integrated Continental Scientific Drilling Program (ICDP) are also considering research in the Beaufort Sea and our research would provide site survey data in support of active drilling proposals.
In December 2015, we have installed neutron monitor at the Jang Bogo station in Antarctica. The Jang Bogo station is the second science station which is located at the coast (74° 37.4'S, 164° 13.7'E) of Terra Nova Bay in Northern Victoria Land of Antarctica. A neutron monitor is an instrument to detect neutrons from secondary cosmic rays collided by the atmosphere. The installation of neutron monitor at Jang Bogo station is a part of transferred mission for neutron monitor at McMurdo station of USA. Among 18 tubes of 18-NM64 neutron monitor, we have completed relocation of 6 tubes and the rest will be transferred in December 2017. Currently, comparison of data from both neutron monitors is under way and there is a good agreement between the data. The neutron monitor at Jang Bogo station will be quite useful to study the space weather when the installation is completed.
In extreme environments, such as the Arctic, endolithic communities are most of the extant life. The endolithic environment is thought to buffer microbial com-munities from intense solar radiation, temperature fluctuations, wind, and desiccation in environments where such environmental factors inhibit epilithic growth. Therefore, the endolithic environment is a critical habitat to explore in exobiological research.
The abundance of endolithic life in the high Arctic, combined with the potential for biosignature preserva-tion, suggests that rocks associated with endolithic ecosystems may be the best hope for finding fossil evidence of past life on the Martian surface.
The goal of this study is to assess the activity and community composition of the endolithic community inhabiting rocks in the Norwegian high Arctic. To achieve this goal, we combined techniques of DNA sequencing, microscopy and spectroscopy. This work provides an overview of the polar microbial communi-ty and a new recognition of how environmental stresses such as prevailing polar desert conditions may affect the biogeochemical dynamics of high Arctic endolithic microorganisms.
In general, most chemical reactions are slowed down when temperature decreases. However, several chemical processes can be enhanced in frozen state. The bioavailability, mobility, toxicity, and environmental fate of metals or inorganic elements are controlled by their redox speciation. Although the chemical processes in ice play an critical role on various environmental system, they have rarely studied. Firstly, we investigated the dissolution of bioavailable trace elements (Fe(II)aq and Mn(II)aq) from their oxide particles in water and ice. The dissolution of metal (iron and manganese) oxides particles in ice phase was significantly enhanced compared to those in aqueous solution both in the presence and absence of light although the dissolution rate was enhanced under UV irradiation. The dissolution rate depends on crystallinity, BET surface areas, kinds of present organics or inorganics, pH, light sources, presence of oxygen, and etc. We also investigated the reduction of Cr(VI) in the presence of organic/inorganic compounds and the simultaneous transformation of Cr(VI) and As(III) in ice in comparison with those in aqueous solution. The reduction of Cr(VI) by various organic acids (electron donors) or H<sub>2</sub>O<sub>2</sub> was negligible in ambient aqueous solution but was significantly accelerated in ice. The reduction of Cr(VI) in the presence of H<sub>2</sub>O<sub>2</sub> in ice shows different reaction pathway compared to those in aqueous solution. The simultaneous reduction of Cr(VI) and oxidation of As(III) in ice phase proceeded stoichiometrically, whereas their mutual conversion was insignificant in aqueous solution. The enhanced redox transformation in ice phase is ascribed to the freeze concentration effect (when solution is solidified the existed organic and inorganic compounds are highly concentrated in unfrozen liquid-like regions) in ice crystal grain boundaries. These results imply that understanding the redox conversion of various inorganic/organic compounds in ice phase may provide newer views and insights on the environmental chemical processes in the icy environments (e.g., upper troposphere, permafrost, polar/high latitude environment and mid-latitudes during winter season) where the freeze-thaw cycles repeat. We also found that the oxidation of iodide to form I3- and I<sub>2</sub> is greatly accelerated in frozen solution, which is even more enhanced under natural solar irradiation. The release of gaseous I<sub>2</sub> upon thawing the irradiated ice was detected by using cavity ring down spectroscopy. The ice-enhanced generation of I<sub>3</sub><sup>-</sup> and I<sub>2</sub> is ascribed to the freeze concentration of iodide and dissolved O<sub>2</sub> trapped in polycrystalline ice grain boundaries. This finding proposes a previously unrecognized source of gaseous I<sub>2</sub> through abiotic process in polar region. Here, we introduce our previous studies on intrinsic chemical processes of inorganic species in ice phase and its environmental implications.
In high-latitude regions, temperature has risen (0.6°C per decade) and this leads to the increase in microbial degradability against soil organic carbon (SOC). Furthermore, the decomposed SOC is converted into green-house gases (CO2 and CH4) and their release could further increase the rate of climate change. Thus, understanding the microbial diversity and their functions linked with SOC degradation in soil-thawing model is necessary. In this study, we divided tundra soil from Council, Alaska into two depth regions (30-40 cm and 50-60 cm of depth, designated as SPF and PF, respectively) and incubated that for 108 days at 0°C. A total of 111,804 reads were obtained through a pyrosequencing-based metagenomic study during the microcosm experiments, and 574-1,128 of bacterial operational taxonomic units (OTUs) and 30-57 of archaeal OTUs were observed. Taxonomic analysis showed that the distribution of bacterial taxa was significantly different between two samples. In detail, the relative abundance of phyla Actinobacteria and Firmicutes largely increased in SPF and PF soil, respectively, while phyla Crenarchaeota was increased in both soil samples. Weight measurement and gel permeation chromatography of the SOC extracts demonstrated that polymerization of humic acids, main component of SOC,
occurred during the microcosm experiments. Taken together our results indicate that these bacterial and archaeal phyla could play a key function in SOC degradation and utilization in cold tundra soil.
In high-latitude regions, temperature has risen twice as fast as the global average (0.3°C per decade) and this leads to the increase in microbial degradability against soil organic carbon (SOC). Furthermore, the decomposed SOC is converted into green-house gases(CO<sub>2 </sub>and CH<sub>4</sub>) and their release could further increase the rate of climate change. Thus, understanding the microbial diversity and their functions linked with SOC degradation in soil-thawing model is necessary. In this study, we divided SOC-rich tundra soil from Council, Alaska into two depth regions (30-40 cm and 50-60 cm of depth) and incubated that for 108 days at 0°C. A total of 111,804 reads were obtained through a pyrosequencing-based metagenomic study during the microcosm experiments, and 574-1,128 of bacterial operational taxonomic units (OTUs) and 30-57 of archaeal OTUs were observed. Taxonomic analysis showed that the distribution of bacterial taxa was significantly different between two samples, while archaea was similar. In detail, the relative abundance of phyla Actinobacteria and Firmicutes largely increased in 30-40 cm and 50-60 cm of soil depths, respectively. Genera Oryzihumus (30-40 cm) and Desulfosporosinus (50-60 cm) were predominant in Actinobacteria and Firmicutes, respectively. Weight measurement and gel permeation chromatography of the SOC extracts demonstrated that polymerization of humic acids, main component of SOC, occurred during the microcosm experiments. Taken together our results indicate that these two bacterial phyla could play a key function in SOC degradation and utilization in cold tundra soil.
In high-latitude regions, temperature has risen twice as fast as the global average (0.3°C per decade) and this leads to the increase in microbial degradability against soil organic carbon (SOC). Furthermore, the decomposed SOC is converted into green-house gases(CO<sub>2</sub> and CH<sub>4</sub>) and their release could further increase the rate of climate change. Thus, understanding the microbial diversity and their functions linked with SOC degradation in soil-thawing model is necessary. In this study, we divided SOC-rich tundra soil from Council, Alaska into two depth regions (30-40 cm and 50-60 cm of depth) and incubated that for 108 days at 0°C. A total of 111,804 reads were obtained through a pyrosequencing-based metagenomic study during the microcosm experiments, and 574-1,128 of bacterial operational taxonomic units (OTUs) and 30-57 of archaeal OTUs were observed. Taxonomic analysis showed that the distribution of bacterial taxa was significantly different between two samples, while archaea was similar. In detail, the relative abundance of phyla Actinobacteria and Firmicutes largely increased in 30-40 cm and 50-60 cm of soil depths, respectively. Genera Oryzihumus (30-40 cm) and Desulfosporosinus (50-60 cm) were predominant in Actinobacteria and Firmicutes, respectively. Weight measurement and gel permeation chromatography of the SOC extracts demonstrated that polymerization of humic acids, main component of SOC, occurred during the microcosm experiments. Taken together our results indicate that these two bacterial phyla could play a key function in SOC degradation and utilization in cold tundra soil.
In order to understand terrestrial ecosystem in Barton Peninsula, we have evolved a multidisciplinary project. There are six main components which sustain terrestrial ecosystem. As biotic factors, we considered microflora, flora and fauna, whereas climate, geomorphology and geochemistry can be considered as abiotic factors. Each component also has several sub-factors. For example, geomorphology has such altitude, aspect and slope. Components are related to each other. Climate can affect the composition of microbial flora, flora, fauna and geochemistry, while climate can be affected by geomophology.
Over the last few decades, terrestrial environments in Antarctica had been believed as sterilized habitats without any life forms because of the extreme conditions. In recent years, expansions of molecular biological methods to study microbial communitieshave detected unexpectedly high diversity and complexity of bacteria community in this harsh environment. Actinobacteria, Bacteroidetes, Gemmatimonadetesand Alphaproteobacteriawere dominant in McMurdo Dry Valleys of Antarctic continent (Lee, et al., 2011). Then, how about maritime Antarctica? Which bacterial phyla are dominant and how similar are bacterial community structures between soilhabitats in this region? We conducted a comprehensive analysis of bacterial communities in soil samples from Barton Peninsular in Antarctica. In total 258 soil samples from 51 sites were collected during the period from December 2010 to February 2012. Among these samples, we here present preliminary results with 85 samples in 15 sites.
In order to understand the carbon cycle in the Amundsen Sea o f the Southem Ocean, the export t1uxes o f particulate organic carbon from the euphotic zone to deep water estimated using <sup>234</sup>Th<sup>238</sup>U disequilibrium method. Seawaters in 14 water columns were collected during February and March 2012, and analyzed for total and dis- solved and organic carbon. Total <sup>234</sup>Th activities in the water column showed deficiency and excess relative to those of <sup>238</sup>U depending on the water depth. Deficiency of total in the euphotic zone showed mirror images both with chlorophyll-a and f1uorescence, and was consistent with the loss of nitrate, which indicated the effect ofbiological activity. In addition,deficiency of total <sup>234</sup>Th from deep water was associated with the increase oftotal dissolvable Fe/Mn concentration. Excess total <sup>234</sup>Th activity below the euphotic zone might be related to <sup>234</sup>Th concentrated in this water depth. Mean export flux of <sup>234</sup>Th estimated using the steady state model was 867 ± 246 dpm m<sup>-2</sup>day<sup>-1</sup> Mean export flux of particulate organic carbon, which were estimated by the product of total <sup>234</sup>Th flux and ratio of POC/<sup>234</sup>Th (7.08 ± 4.27 umol C dpm<sup>-1</sup>)in the sinking particles, was 5.9 ± 3.9 mmol C m<sup>-2</sup>day<sup>-1</sup>. These fluxes were similar levels to those in the Weddell Sea during February and March 2008. Export ratios (ThE) relative to the primary production in the euphotic zone were in the range o f3-54% (av. 28%).
In summer 2015, two ocean mooring systems were recovered in the Chukchi Plateau (CP), which had been deployed over the northern CP in 2013 (nCP13) and the southern CP in 2014 (sCP14), respectively. Yearlong temperature and water velocity data show spatial and temporal variations of the Pacific summer water (PSW) over the CP. During the autumn 2014, especially, the period that PSW was weakened in nCP13 coincides with the period that PSW appeared in sCP14. Northeasterly winds and sea ice covering appear to play an important role in initiating substantial heat release/storage within the PSW layer from October and mid-winter of 2014. This study will focus on understanding how winds and sea ice have an influence on the distribution of PSW over the CP through the intensive analysis of the mooring data.
In the Arctic the impact of contemporary global warming accelerates the melting of glaciers since the end of the Little Ice Age (LIA). Alongside great glaciers and ice caps that give the key trends and regional rhythms of contemporary dynamics it is interesting to focus the research on small systems foothills. These provide information on the dynamics paraglacial who help shape the landscape while the glacier is no longer while releasing surfaces for gas exchange with the atmosphere - especially soil organic carbon - previously blocked by ice. Moraines are so privileged place where spend most of the dynamics, while runoff is increasing because of the melting and remobilised chaotic shapes of glacial deposits, vegetation - if scattered is it - tends to contrary to stabilize the substrate while providing a diversity that is not found in the oldest areas equilibrium, such as the open tundra installed since the last major glaciation of the Weichselian (110 000 - 10 000 years) at the beginning Holocene. Spitsbergen (Svalbard) in the Bay of Roy on the western coast of the island, the site of glaciers Loven (79 ° N, 12 ° E) is the subject since the early 60's environmental research that diversified since the creation of the international base of Ny-Alesund in 2000. This research is based inter alia on geographic data that can keep pace with the melting since 1936 (topographic maps and aerial photographs). An integrated approach to the dynamics of the processes involved in the moraines also requires detailed knowledge of the terrain and its remobilization by runoff. The Digital Elevation Models (DEM) derived from ancient documents did not provide sufficient spatial resolution and accuracy to integrate survey data into the modeling of the phenomena studied. Since the early 90s we used to survey campaigns DGPS (Differential Global Positioning System) to obtain very sharp images of terrain but the approach is limited by the small surface that can be covered with a density sufficient points for honor details awaited. Stereoscopic data ASTER GDEM (Global Digitized Elevation Model) or SPOT 5 HRG (High Resolution Geometric) do not meet either of these requirements. Airborne LIDAR turns out very accurate but if it is only the cost of an airborne mission to Spitsbergen is unacceptable. The Pleiades data therefore seem ideal to meet our expectations, spatial resolutions and elevation details announced meet our requirements. We intend to demonstrate here the relevance of MNE Pleiades (tri-stereoscopic stereoscopic April 2013 and August 2013) to integrate the parameters of relief (elevation, slope, orientation, roughness, fractal dimension, watershed drains, niches ...) in the analysis of environmental phenomena involved in the moraines of the LIA.
In the austral summer of 2012/2013 and 2014/2015, Korea Polar Research Institute (KOPRI) has conducted multichannel seismic (MCS) survey in the Central Basin of the Ross Sea, Antarctica. One of the objectives of the survey is to support for the IODP 751 proposal by providing site survey data for drilling safety. In addition, new seismic profiles are expected to provide unknown sedimentary features in the slope of the Central Basin. The aim of the study is to reconstruct the paleo-depositional environment, based on the seismic stratigraphy from the outer shelf to lower slope of the Central Basin (west of the Iselin Bank), from mid Miocene to the present. Because the Ross Sea is one of the main glacial drainage outlets of the Antarctic Ice Sheet (AIS), the reconstruction will help a better understanding of the evolution of the Antarctic Ice Sheet (AIS). For extensive interpretation, we combined MCS data collected by KOPRI and the Italian Antarctic research program (PNRA). We also included MCS data stored in the Antarctic Seismic Data Library System (SDLS).
For the interpretation, major ANTOSTRAT seismic horizons in the inner shelf of the Ross Sea were extended to the continental slope and rise. The seismic grid was used for seismic sequence mapping (1) to reconstruct paleo-bathymetry at RSU4 (mid-late Miocene) and RSU2 (late Pliocene-early Pleistocene) times and (2) to calculate sedimentation rates since RSU4 time. The seismic profiles in the slope of the Central Basin show well-stratified aggradational sedimentary sequence from the outer shelf to the lower slope between RSU4 and RSU2 horizons. Above RSU2 horizon, prograding wedges developed in the outer shelf and upper slope. Sediment drift features are well developed along the slope of the Central Basin. The paleo-bathymetry at RSU4 and RSU2 appears to be similar to present-day topography. Paleo-shelf break and depocenter at the mouth of Joides Basin migrated basinward throughout the mid-late Cenozoic time. The preliminary results of this study document the advance of the AIS over the shelf edge of the Central Basin region after RSU2 time. Abrupt change of seismic facies above RSU2 at the mouth of Joides Basin may imply that the depositional environment changed due to a variation of ice regime in the Ross Sea after late Pliocene-early Pleistocene. Bottom water activities since mid Cenozoic (above RSU4) time formed the sediment drift features in the Central Basin. Bottom current pathway seems to be similar to modern general circulation.
In the course of a bioassay-guided study of metabolites from the marine fungus
Eurotium sp. SF-5989, two diketopiperazine type indole alkaloids, neoechinulins A and B,
were isolated. In this study, we investigated the anti-inflammatory effects of neoechinulins
A (1) and B (2) on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages.
Neoechinulin A (1) markedly suppressed the production of nitric oxide (NO) and
Molecules 2013, 18 13246
prostaglandin E2 (PGE2) and the expression of inducible nitric oxide synthase (iNOS) and
cyclooxygenase-2 (COX-2) in a dose dependent manner ranging from 12.5 μM to 100 μM
without affecting the cell viability. On the other hand, neoechinulin B (2) affected the cell
viability at 25 μM although the compound displayed similar inhibitory effect of NO
production to neoechinulin A (1) at lower doses. Furthermore, neoechinulin A (1)
decreased the secretion of pro-inflammatory cytokines, such as tumor necrosis factor-α
(TNF-α) and interleukin-1β (IL-1β). We also confirmed that neoechinulin A (1) blocked
the activation of nuclear factor-kappaB (NF-κB) in LPS-stimulated RAW264.7
macrophages by inhibiting the phosphorylation and degradation of inhibitor kappa B (IκB)-α.
Moreover, neoechinulin A (1) decreased p38 mitogen-activated protein kinase (MAPK)
phosphorylation. Therefore, these data showed that the anti-inflammatory effects of
neoechinulin A (1) in LPS-stimulated RAW264.7 macrophages were due to the inhibition
of the NF-κB and p38 MAPK pathways, suggesting that neoechinulin A (1) might be a
potential therapeutic agent for the treatment of various inflammatory diseases.
In the course of a search for anti-inflammatory metabolites from marine-derived
fungi, methylpenicinoline (1) was isolated from a marine isolate of Penicillin sp. Compound
1 inhibited lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production by suppressing the expression of inducible NO synthase (iNOS) in RAW264.7 macrophages and BV2 microglia. It also attenuated prostaglandin E<sub>2</sub> (PGE<sub>2</sub>) production by suppressing
cyclooxygenase-2 (COX-2) expression in a concentration-dependent manner (from 10 μM to 80 μM) without affecting cell viability. In addition, compound 1 reduced the production of the pro-inflammatory cytokine interleukin-1β (IL-1β). In a further study designed to elucidate the mechanism of its anti-inflammatory effects, compound 1 was shown to block nuclear factor-kappa B (NF-κB) activation in LPS-induced RAW264.7 macrophages and
BV2 microglia by inhibiting the phosphorylation of inhibitor kappa B-α (IκB-α), thereby suppressing the nuclear translocation of NF-κB dimers, namely p50 and p65, that are known to be crucial molecules associated with iNOS and COX-2 expression. In addition, compound 1 inhibited the activation of mitogen-activated protein kinase (MAPK) pathways.Taken together, the results suggest that compound 1 might be a valuable therapeutic agent for the treatment of anti-inflammatory and anti-neuroinflammatory diseases.
In the course of a search for anti-neuroinflammatory metabolites from marine fungi, aurantiamide acetate (1)
was isolated from marine-derived Aspergillus sp. as an anti-neuroinflammatory component. Compound 1 dosedependently
inhibited the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in BV2 microglial cells.
It also attenuated inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), and other pro-inflammatory
cytokines, such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). In a further study designed to
elucidate the mechanism of its anti-neuroinflammatory effect, compound 1 was shown to block the activation
of nuclear factor-kappa B (NF-κB) in lipopolysaccharide (LPS)-induced BV2 microglial cells by inhibiting the
phosphorylation of the inhibitor kappa B-α (IκB)-α. In addition, compound 1 decreased the phosphorylation
levels of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPKs). These results
suggest that compound 1 has an anti-neuroinflammatory effect on LPS stimulation through its inhibition of the
NF-κB, JNK and p38 pathways.
In the course of searching for bioactive secondary metabolites from marine fungi,
TMC-256C1 was isolated from an ethyl acetate extract of the marine-derived fungus Aspergillus sp.
SF6354. TMC-256C1 displayed anti-neuroinflammatory effect in BV2 microglial cells induced by
lipopolysaccharides (LPS) as well as neuroprotective effect against glutamate-stimulated neurotoxicity
in mouse hippocampal HT22 cells. TMC-256C1 was shown to develop a cellular resistance to
oxidative damage caused by glutamate-induced cytotoxicity and reactive oxygen species (ROS)
generation in HT22 cells, and suppress the inflammation process in LPS-stimulated BV2 cells.
Furthermore, the neuroprotective and anti-neuroinflammatory activities of TMC-256C1 were
associated with upregulated expression of heme oxygenase (HO)-1 and nuclear translocation of
nuclear factor-E2-related factor 2 (Nrf2) in HT22 and BV2 cells. We also found that TMC-256C1
activated p38 mitogen-activated protein kinases (MAPK) and phosphatidylinositol 3-kinase
(PI3K)/Akt signaling pathways in HT22 and BV2 cells. These results demonstrated that TMC-256C1
activates HO-1 protein expression, probably by increasing nuclear Nrf2 levels via the activation of
the p38 MAPK and PI3K/Akt pathways.
In the current study, the community composition of bacteria were investigated the perennial ice-covered lakes in the fine scale using 454-pyrosequencing; Fryxell (FRX), Hoare (HOR) and Miers (MIE). Based on 16S rRNA gene, total 124,803 sequences were quality filtered using 97% similarity cutoff, and 55 phyla were recovered containing the major phyla Actinobacteria (29%), Bacteroidetes (24.4%) and Proteobacteria (14%). In the phylum level, the bacterial taxonomy were highly shown the heterogeneous communities. Overall, microbial community composition varies not only between lakes, but also along the depth gradients within lake. Taken together, the diversity of microbial communities in lakes of MDVs provided a crucial evidence to understand the impact of microbial ecological roles in these ecosystems.
In the late 2000s, the dominant sea ice type
in the Arctic Ocean changed from multi-year ice to firstyear
ice. In this condition, winter growth of first-year ice
and resultant ice thickness at the melt onset are key preconditions
on whether sea ice can survive or will disappear
during the following summer. The growth rate
strongly depends on upper ocean thermal conditions. In
the Pacific sector of the Arctic Ocean, the warm Pacific
Summer Water, which is a major heat source affecting the
sea ice growth, is transported toward the basin by the oceanic
Beaufort Gyre, driven by winds and sea ice motions,
but the response time scale of the oceanic Beaufort Gyre
to surface forcing has been unclear until now. In the present
study, we examine the relationship between the ocean
dynamic height near the Northwind Ridge as a proxy of
the northward volume transport and curls of winds and sea
ice velocities, using multiple regression models that evaluate
relative contributions of past surface forcing to the current
state of the oceanic Beaufort Gyre. As a result, the
time scale of the delayed oceanic response in 2006？2012
was estimated to be about 3 years. Taking into account the
response time scale, the multiple regression model using
the satellite-derived sea ice motion data successfully reconstructed
the observed variations of ocean dynamic heights within an accuracy of 0.2 dynamic cm, which corresponded
to about 2 % of the amplitude of the observed variations.
In the recent seafloor mapping surveys in the western Arctic, the Quaternary glacigenic bedforms have been ubiquitously recognized including iceberg scours, till deposits, mega-scale glacial lineations and moraines. This study focuses on the Chukchi Sea, a part of the glacier-influenced western Arctic margins, where the high-resolution stratigraphic and echo facies analyses were carried out using the sub-bottom profiles (SBP). The SBP data were obtained during the Arctic expeditions of R/V Araon (operated by KOPRI) in 2011 and 2012. Echo facies is classified on the basis of seafloor geometry and characters of sub-bottom reflection within the high-resolution stratigraphic framework. On the SBP data, two stratigraphic units (units I and II in descending order) are recognized by two distinctive sub-bottom reflectors of which lateral continuity is more or less variable. Stratigraphic unit I consists of parallel to sub-parallel stratified (A) and transparent reflections (C) with flat or undulating topography (I). Echo facies IA is frequently observed in the Chukchi continental shelf while it is absent or very thin toward deeper water. Echo facies IC is found below ~360 m water depth. Instead, sediment infills on top of iceberg-ploughed seafloor are locally recognized in the Chukchi continental shelf. Echo facies IA and IC as well as this sediment infill are interpreted as Holocene sediments by marine transgression and hemipelagic settling. Unit II is quite variable in thickness and generally consists of echo facies IIIB and IIB that show overlapping hyperbolae and hummocks (III) and highly dissected topography (II) with random or fuzzy sub-bottom reflection (B). Echo facies IIIB and IIB dominantly occur between 150 m to 360 m in water depth. Acoustically fuzzy and unstratified reflection can be generated from subglacial tills beneath the grounded glacier. Echo facies IIIB or IIB shows distinct or erosive lower boundaries in some places, which indicates that stratigraphic unit II formed during the glacial retreat. Highly dissected topography of echo facies IIB suggests that glacial tills were reworked by iceberg scouring. Distribution of these echo facies and stratigraphic units in the Chukchi continental margin suggests that Chukchi shelf and rise areas were effected by the retreating grounded ice during last deglaciation.
In the western Ross Sea it has generally been considered that a thick ice sheet was grounded to the sea floor during the last glacial maximum (LGM) and the retreat of the ice sheet did not begin until ~13 ky BP. A gravity core (DG12-GC06) from the southern Drygalski Trough in the southwestern Ross Sea, however, raises a question about the stability of the Ross Ice Sheet during the last glacial period. ‘Typical’ Ross Sea sequence of LGM to Holocene age is composed of diatomaceous mud and underlying diamicton. The core sediment from the southern Drygalski Trough also contains post-glacial diatomaceous mud (‘upper’ mud) and glacial stratified diamicton, but the diamicton layers are overlain by another, ‘lower’ diatomaceous mud layers. The presence of ‘lower’ mud beneath diamicton indicates a seasonally open marine environment prior to/during the last glacial event in the southwestern Ross Sea. Radiocarbon dates of acid-insoluble organic matter (AIO) from the ‘lower’ mud range from ~32 to 39 ky BP. AIO radiocarbon age of surface sediment is ~4ky BP and corrected age based on surface sediment age is ~28 to 35 ky BP. However, this kind of age correction is ratified only when composition of organic matter of surface sediment is similar to that of the ‘lower’ mud. We applied ramped pyrolysis technique for radiocarbon dating of the ‘lower’ mud to date younger organic matter fraction, which produced ages of 22~23 ky BP. It seems that ice sheet on the western Ross Sea retreated at ~24 ky BP and advanced at ~21 ky BP. In order to preserve the ‘lower’ mud, we infer that the second advance featured a thinner ice sheet than the initial advance.
In this study, a high lipid-accumulating mutant strain of the microalgae Scenedesmus dimorphus was developed via radiation breeding. To induce mutant strain, S. dimorphus was gamma-irradiated at doses from 100 to
800 Gy, and then a mutant (Sd-Pm210) with 25 % increased lipid content was selected using Nile red staining methodology. Sd-Pm210 showed morphological changes and had higher growth rate compared to the wild type.
From random amplified polymorphic DNA analysis, partial genetic modifications were also observed in Sd-Pm210. In comparisons of lipid content between wild type and Sd- Pm210 using thin-layer chromatography, the content of
triacylglycerol was markedly higher in the Sd-Pm210 strain. The total peak area of fatty acid methyl ester was shown to have about 1.4-fold increase in Sd-Pm210, and major fatty acids were identified as palmitic acid, oleic
acid, linoleic acid, and linolenic acid. To define the metabolic changes in the mutant strain, 2-dimensional electrophoresis was conducted. Several proteins related to lipid synthesis and energy metabolisms were overexpressed in
the mutant strain. These results showed that radiation breeding can be utilized for the development of efficient microalgae strains for biofuel production.