scholarly journals Host-associated phages disperse across the extraterrestrial analogue Antarctica

2021 ◽  
Author(s):  
Janina Rahlff ◽  
Till L.V. Bornemann ◽  
Anna Lopatina ◽  
Konstantin Severinov ◽  
Alexander J Probst
Keyword(s):  
Polymorphism Analysis ◽  
Polar Regions ◽  
Biological Contaminants ◽  
Complete Alignment ◽  
Antarctic Snow ◽  
Antarctic Continent ◽  
Biological Entities ◽  
Genetic Signatures ◽  
The Antarctic ◽  
Harsh Conditions

Extreme Antarctic conditions provide one of the closest analogues of extraterrestrial environments. Since air and snow samples especially from polar regions yield DNA amounts in the lower picogram range, binning of prokaryotic genomes is challenging and renders studying the dispersal of biological entities across these environments difficult. Here, we hypothesized that dispersal of host-associated bacteriophages (adsorbed, replicating or prophages) across the Antarctic continent can be tracked via their genetic signatures and benefits our understanding of virus and host dispersal across long distances. Phage genome fragments (PGFs) reconstructed from surface snow metagenomes of three Antarctic stations were assigned to four host genomes, mainly Betaproteobacteria including Ralstonia spp. Betaproteobacteria of this genus have been found in Antarctic snow as well as on space-related equipment. We reconstructed the complete genome of a temperate phage with near-complete alignment to a prophage in the reference genome of Ralstonia pickettii 12D. PGFs from different stations were related to each other at the genus level and matched similar hosts. Metagenomic read mapping and nucleotide polymorphism analysis revealed a wide dispersal of highly identical PGFs, 13 of which appeared in seawater from the Western Antarctic Peninsula with up to 5538 km to the snow sampling stations. Our results suggest that host-associated phages, especially of Ralstonia sp. disperse over long distances despite harsh conditions of the Antarctic continent. Due to the additional identification of 14 phages associated with two R. pickettii draft genomes isolated from space equipment, we conclude implications for the spread of biological contaminants in extraterrestrial settings.

scholarly journals Temporal Distribution of Arsenic and Metals in Soil From King George Island, Antarctica

2022 ◽  
Vol 8 ◽  
Author(s):  
Tailisi H. Trevizani ◽  
Rosalinda C. Montone ◽  
Rubens C. L. Figueira
Keyword(s):  
Human Activities ◽  
Temporal Distribution ◽  
Polar Regions ◽  
Control Points ◽  
King George Island ◽  
Admiralty Bay ◽  
Direct Exposure ◽  
Antarctic Continent ◽  
The Antarctic ◽  
Continue Monitoring

The polar regions are vulnerable to impacts caused by local and global pollution. The Antarctic continent has been considered an environment that has remained little affected by human activities. Direct exposure to contaminants may occur in areas continuously occupied by research stations for several decades. Admiralty Bay on the southeast coast of King George Island, has potential for being affected by human activities due research stations operating in the area, including the Brazilian Commandant Ferraz Antarctic Station (CFAS). The levels of metals and arsenic were determined in soils collected near CFAS (points 5, 6, 7, and 9), Base G and at two points distant from the CFAS: Refuge II and Hennequin. Samples were collected after the fire in CFAS occurred in February 2012, up to December 2018 to assess the environmental impacts in the area. Al and As were related with Base G. Refuge II and Hennequin can be considered as control points for this region. As a consequence of the accident, the increased levels for Cd, Cu, Pb, and Zn, especially at point 9 (inside the CFAS) and in the soil surrounding the CFAS in 2013. The results from 2016 to 2018 demonstrated a reduction in levels of all studied metals near CFAS, which may be related to the leaching of metals into Admiralty Bay; it is thus, being important the continue monitoring soil, sediments, and Antarctic biota.

scholarly journals Weather Observations of Remote Polar Areas Using an AWS Onboard a Unique Zero-Emissions Polar Vehicle

2019 ◽  
Vol 100 (10) ◽  
pp. 1891-1895 ◽  
Author(s):  
Sergi Gonzalez ◽  
Manuel Bañon ◽  
José V. Albero ◽  
Ramón Larramendi ◽  
Hermenegildo Moreno ◽  
...  
Keyword(s):  
Climate Models ◽  
Weather Forecasting ◽  
Meteorological Data ◽  
Polar Regions ◽  
Large Set ◽  
Antarctic Plateau ◽  
Weather Observations ◽  
Unique Zero ◽  
The Antarctic ◽  
Harsh Conditions

AbstractThe Antarctic Plateau is one of the land areas with the largest gaps in surface weather observations on Earth, gaps that are usually filled with simulations provided by climate models. However, these simulated values must be ground-validated, which is particularly difficult and costly in remote polar regions. We designed and developed a Mobile Automatic Weather Station (M-AWS) which, on board a zero-emissions polar vehicle, recorded a large set of ground measurements that could be used to evaluate numerical weather simulations in an inexpensive way during the Year of Polar Prediction Southern Hemisphere Special Observing Period (YOPP). The M-AWS registered several weather variables over a transect of 2538 km in the East Antarctic Plateau. These meteorological data were also used by other scientific projects that were part of the expedition and for improving weather forecasting during the mission. The innovative design of the M-AWS overcame the main challenges imposed by the harsh conditions of a voyage in one of the world’s most extreme regions.

Lichens of the Oasis Molodyozhnyi and adjacent areas (Enderby Land, Antarctic)

2013 ◽  
Vol 47 ◽  
pp. 167-178 ◽  
Author(s):  
M. P. Andreev
Keyword(s):  
Liquid Water ◽  
Climate Conditions ◽  
Water Ice ◽  
Buellia Frigida ◽  
Antarctic Continent ◽  
Harsh Climate ◽  
The Antarctic ◽  
First Time ◽  
Lichen Flora

Lichen flora and vegetation in the vicinity of the Russian base «Molodyozhnaya» (Enderby Land, Antarctica) were investigated in 2010–2011 in details for the first time. About 500 specimens were collected in 100 localities in all available ecotopes. The lichen flora is the richest in the region and numbers 39 species (21 genera, 11 families). The studied vegetation is very poor and sparse, but typical for coastal oases of the Antarctic continent. The poorness is caused by the extremely harsh climate conditions, insufficient availability of liquid water, ice-free land, and high insolation levels. The dominant and most common lichens are Rinodina olivaceobrunnea, Amandinea punctata, Candelariella flava, Physcia caesia, Caloplaca tominii, Lecanora expectans, Caloplaca ammiospila, Lecidea cancriformis, Pseudephebe minuscula, Lecidella siplei, Umbilicaria decussata, Buellia frigida, Lecanora fuscobrunnea, Usnea sphacelata, Lepraria and Buellia spp.

scholarly journals Accuracy Analysis of International Reference Ionosphere 2016 and NeQuick2 in the Antarctic

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1551
Author(s):  
Zihuai Guo ◽  
Yibin Yao ◽  
Jian Kong ◽  
Gang Chen ◽  
Chen Zhou ◽  
...  
Keyword(s):  
Solar Radiation ◽  
International Reference Ionosphere ◽  
Electron Content ◽  
Observation Data ◽  
Dual Frequency ◽  
Total Electron ◽  
International Reference ◽  
Antarctic Continent ◽  
The Antarctic ◽  
Frequency Observation

Global navigation satellite system (GNSS) can provide dual-frequency observation data, which can be used to effectively calculate total electron content (TEC). Numerical studies have utilized GNSS-derived TEC to evaluate the accuracy of ionospheric empirical models, such as the International Reference Ionosphere model (IRI) and the NeQuick model. However, most studies have evaluated vertical TEC rather than slant TEC (STEC), which resulted in the introduction of projection error. Furthermore, since there are few GNSS observation stations available in the Antarctic region and most are concentrated in the Antarctic continent edge, it is difficult to evaluate modeling accuracy within the entire Antarctic range. Considering these problems, in this study, GNSS STEC was calculated using dual-frequency observation data from stations that almost covered the Antarctic continent. By comparison with GNSS STEC, the accuracy of IRI-2016 and NeQuick2 at different latitudes and different solar radiation was evaluated during 2016–2017. The numerical results showed the following. (1) Both IRI-2016 and NeQuick2 underestimated the STEC. Since IRI-2016 utilizes new models to represent the F2-peak height (hmF2) directly, the IRI-2016 STEC is closer to GNSS STEC than NeQuick2. This conclusion was also confirmed by the Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) occultation data. (2) The differences in STEC of the two models are both normally distributed, and the NeQuick2 STEC is systematically biased as solar radiation increases. (3) The root mean square error (RMSE) of the IRI-2016 STEC is smaller than that of the NeQuick2 model, and the RMSE of the two modeling STEC increases with solar radiation intensity. Since IRI-2016 relies on new hmF2 models, it is more stable than NeQuick2.

Dimethysulfide concentrations in the ocean close to the antarctic continent

1988 ◽  
Vol 6 (3-4) ◽  
pp. 179-184 ◽  
Author(s):  
John A.E. Gibson ◽  
Russell C. Garrick ◽  
Harry R. Burton ◽  
Andrew R. McTaggart
Keyword(s):  
Antarctic Continent ◽  
The Antarctic

Soil tardigrades from the Antarctic Peninsula with a description of a new species and some remarks on the genusRamajendas(Eutardigrada: Isohypsibiidae)

Polar Record ◽  
2013 ◽  
Vol 50 (2) ◽  
pp. 176-182 ◽  
Author(s):  
Łukasz Kaczmarek ◽  
Karel Janko ◽  
Jerzy Smykla ◽  
Łukasz Michalczyk
Keyword(s):  
New Species ◽  
Antarctic Peninsula ◽  
Morphometric Characters ◽  
Antarctic Continent ◽  
Fourth Species ◽  
The Antarctic ◽  
A New Species ◽  
Mixed Samples ◽  
Hypsibius Dujardini

ABSTRACTIn thirteen (mostly soil) mixed samples, collected from nine localities on the Antarctic continent and some of the neighbouring islands, 788 specimens and 32 eggs of tardigrades were found. In total, five species were identified:Acutuncus antarcticus, Echiniscus jenningsi,Diphascon(D.)victoriae,Hypsibius dujardiniandRamajendas dastychisp. nov.A. antarcticuswas the most abundant (nearly 90% of all specimens) and was the prevailing taxon found in the majority of locations.R. dastychisp. nov. is the fourth species described in the exclusively Antarctic/sub-Antarctic genus. The new species differs from all other congeners by the presence of four gibbosities on the caudo-dorsal cuticle (configuration II:2–2) and also by some morphometric characters. In this paper we also briefly discuss the taxonomy and zoogeography of the genusRamajendas.

Life history strategy of Lepraria borealis at an Antarctic inland site, Coal Nunatak

2010 ◽  
Vol 42 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Andreas ENGELEN ◽  
Peter CONVEY ◽  
Sieglinde OTT
Keyword(s):  
Life History ◽  
Environmental Conditions ◽  
Life History Strategy ◽  
Sequence Polymorphism ◽  
Internal Transcribed Spacer Region ◽  
The West ◽  
Distinctive Features ◽  
Dna Sequence Polymorphism ◽  
Antarctic Continent ◽  
The Antarctic

AbstractCoal Nunatak is an ice-free inland nunatak located on southern Alexander Island, adjacent to the west coast of the Antarctic Peninsula. Situated close to the Antarctic continent, it is characterized by harsh environmental conditions. Macroscopic colonization is restricted to micro-niches offering suitable conditions for a small number of lichens and mosses. The extreme environmental conditions place particular pressures on colonizers. Lepraria borealis is the dominant crustose lichen species present on Coal Nunatak, and shows distinctive features in its life history strategy, in particular expressing unusually low selectivity of the mycobiont towards potential photobionts. To assess selectivity, we measured algal DNA sequence polymorphism in a region of 480–660 bp of the nuclear internal transcribed spacer region of ribosomal DNA. We identified three different photobiont species, belonging to two different genera. We interpret this strategy as being advantageous in facilitating the colonization and community dominance of L. borealis under the isolation and extreme environmental conditions of Coal Nunatak.

On the thickness of the Antarctic ice, and its relations to that of the glacial epoch

2021 ◽  
pp. 1-8
Author(s):  
James CROLL ◽  
David SUGDEN
Keyword(s):  
Thermal Regime ◽  
Freezing Point ◽  
Ice Sheet ◽  
Heat Sources ◽  
Mean Velocity ◽  
Point Estimates ◽  
Glacial Epoch ◽  
Antarctic Continent ◽  
Global Sea Level ◽  
The Antarctic

ABSTRACT At a time when nobody has yet landed on the Antarctic continent (1879), this presentation and accompanying paper predicts the morphology, dynamics and thermal regime of the Antarctic ice sheet. Mathematical modelling of the ice sheet is based on the assumptions that the thickness of tabular icebergs reflects the average thickness of the ice at the margin and that the surface gradients are comparable to those of reconstructed former ice sheets in the Northern Hemisphere. The modelling shows that (a) ice is thickest near the centre at the South Pole and thins towards the margin; (b) the thickness at the pole is independent of the amount of snowfall at that place; and (c) the mean velocity at the margin, assuming a mean annual snowfall of two inches per year, is 400–500 feet per year. The thermal regime of the ice sheet is influenced by three heat sources – namely, the bed, the internal friction of ice flow and the atmosphere. The latter is the most significant and, since ice has a downwards as well as horizontal motion, this carries cold ice down into the ice sheet. Since the temperature at which ice melts is lowered by pressure at a rate of 0.0137 °F for every atmosphere of pressure (something known since 1784), much of the ice sheet and its base must be below the freezing point. Estimates of the thickness of ice at the centre depend closely on the surface gradients assumed and range between 3 and 24 miles. Such uncertainty is of concern since both the volume and gravitational attraction of the ice mass have an effect on global sea level. In order to improve our estimate of the volume of ice, we will have to wait 76 years for John Glen to develop a realistic flow law for ice.

Pathways and timescales of connectivity around the Antarctic continental shelf 

2021 ◽  
Author(s):  
Hannah Dawson ◽  
Adele Morrison ◽  
Veronica Tamsitt ◽  
Matthew England
Keyword(s):  
Continental Shelf ◽  
Ross Sea ◽  
Coastal Current ◽  
West Antarctica ◽  
Source Regions ◽  
Freshwater Forcing ◽  
Antarctic Continental Shelf ◽  
Antarctic Continent ◽  
Antarctic Slope Current ◽  
The Antarctic

<p><span xml:lang="EN-US" data-contrast="auto"><span>The Antarctic margin is surrounded by two westward flowing currents: the Antarctic Slope Current and the Antarctic Coastal Current. The former influences key processes near the Antarctic margin by regulating the flow of heat and nutrients onto and off the continental shelf, while together they </span></span><span xml:lang="EN-US" data-contrast="auto"><span>advect</span></span><span xml:lang="EN-US" data-contrast="auto"><span> nutrients, biological organisms, and temperature and salinity anomalies around the coastline, providing a connective link between different shelf regions. However, the extent to which these currents transport water from one sector of the continental shelf to another, and the timescales over which this occurs, remain poorly understood. Concern that crucial water formation sites around the Antarctic coastline could respond to non-local freshwater forcing </span></span><span><span xml:lang="EN-US" data-contrast="auto"><span>from ice shel</span></span></span><span><span xml:lang="EN-US" data-contrast="auto"><span>f meltwater</span></span></span> <span xml:lang="EN-US" data-contrast="auto"><span>motivates a more thorough understanding of zonal connectivity around Antarctica. In this study, we use daily velocity fields from a global high-resolution ocean-sea ice model, combined with the <span>Lagrangian</span> tracking software Parcels, to investigate the pathways and timescales connecting different regions of the Antarctic continental shelf<span> with a view to understanding</span><span> the timescales of meltwater transport around the continent</span>. Virtual particles are released over the continental shelf, poleward of the 1000 <span>metre</span> isobath, and are tracked for 20 years. Our results show a strong seasonal cycle connecting different sectors of the Antarctic continent, with more particles arriving further downstream during winter than during summer months. Strong advective links exist between West Antarctica and the Ross Sea while shelf geometry in some other regions acts as barriers to transport. We also highlight the varying importance of the Antarctic Slope Current and Antarctic Coastal Current in connecting different sectors of the coastline. Our results help to improve our understanding of circum-Antarctic connectivity <span>and the timescales </span><span>of meltwater transport from source regions to downstream </span><span>shelf locations. </span><span>Further</span><span>more, t</span><span>he timescales and pathways we </span><span>present </span><span>p</span>rovide a baseline from which to assess long-term changes in Antarctic coastal circulation due to local and remote forcing.<br></span></span></p>

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