The effect of irradiance and temperature on the role of photolysis in the removal of organic micropollutants under Antarctic conditions

Environmental context Antarctica has several scientific research stations located along its coast, where they discharge often untreated sewage containing organic micropollutants. Although degradation of these pollutants by microorganisms is limited by the cold conditions, other pathways such as photodegradation may be significant. Our results indicate that, during the summer, photolysis is a potentially significant degradation pathway for organic micropollutants in Antarctic surface waters, although the rate of loss would depend on ice cover and water depth. Abstract Knowledge of the environmental fate of organic micropollutants in Antarctica is limited, especially with respect to photolysis. The Antarctic is characterised by extreme light conditions of either continuous sunshine or darkness depending on the season. The photolytic degradation of benzophenone-3 (BP-3), bisphenol A (BPA), 17α-ethinylestradiol (EE2), methyl paraben (mParaben), 4-t-octylphenol (4-t-OP) and triclosan in MilliQ and seawater was investigated over a range of irradiance levels and temperatures. Photodegradation was compound specific. Up to 20% of BPA, BP-3 and EE2 was degraded over a 7-h irradiance period. Triclosan and 4-t-OP degraded to below the limit of detection in all experiments whereas mParaben was not degraded. The degradation of triclosan increased with irradiance in both MilliQ (P=2.2×10–16) and seawater (P=2.2×10–16). The degradation of 4-t-OP increased with irradiance in MilliQ (P=8.5×10–9) and seawater (P=1.1×10–5), and with temperature in MilliQ (P=8.5×10–9) and seawater (P=1.0×10–5). Similar relationships could not be established for BPA, BP-3, EE2 and mParaben due to the limited extent of degradation observed. The photolysis of triclosan was enhanced 4-fold in seawater compared to MilliQ water. Results from this study indicate that micropollutants may persist for extended periods of time in Antarctic coastal waters, particularly with ice cover, above and beyond that exhibited in temperate seawater.

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Correction to: Environmental fate of tetracycline antibiotics: degradation pathway mechanisms, challenges, and perspectives

Environmental Sciences Europe ◽

10.1186/s12302-021-00511-0 ◽

2021 ◽

Vol 33 (1) ◽

Author(s):

Fiaz Ahmad ◽

Daochen Zhu ◽

Jianzhong Sun

Keyword(s):

Environmental Fate ◽

Degradation Pathway ◽

Tetracycline Antibiotics

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Influence of the Electrolyte Salt Concentration on DNA Detection with Graphene Transistors

Biosensors ◽

10.3390/bios11010024 ◽

2021 ◽

Vol 11 (1) ◽

pp. 24

Author(s):

Agnes Purwidyantri ◽

Telma Domingues ◽

Jérôme Borme ◽

Joana Rafaela Guerreiro ◽

Andrey Ipatov ◽

...

Keyword(s):

Phosphate Buffer ◽

Species Interactions ◽

Field Effect ◽

Field Effect Transistors ◽

Limit Of Detection ◽

Debye Length ◽

Intermolecular Forces ◽

Single Layer Graphene ◽

Dna Adsorption

Liquid-gated Graphene Field-Effect Transistors (GFET) are ultrasensitive bio-detection platforms carrying out the graphene’s exceptional intrinsic functionalities. Buffer and dilution factor are prevalent strategies towards the optimum performance of the GFETs. However, beyond the Debye length (λD), the role of the graphene-electrolytes’ ionic species interactions on the DNA behavior at the nanoscale interface is complicated. We studied the characteristics of the GFETs under different ionic strength, pH, and electrolyte type, e.g., phosphate buffer (PB), and phosphate buffer saline (PBS), in an automatic portable built-in system. The electrostatic gating and charge transfer phenomena were inferred from the field-effect measurements of the Dirac point position in single-layer graphene (SLG) transistors transfer curves. Results denote that λD is not the main factor governing the effective nanoscale screening environment. We observed that the longer λD was not the determining characteristic for sensitivity increment and limit of detection (LoD) as demonstrated by different types and ionic strengths of measuring buffers. In the DNA hybridization study, our findings show the role of the additional salts present in PBS, as compared to PB, in increasing graphene electron mobility, electrostatic shielding, intermolecular forces and DNA adsorption kinetics leading to an improved sensitivity.

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An international hierarchy of science: conquest, cooperation, and the 1959 Antarctic Treaty System

European Journal of International Relations ◽

10.1177/13540661211033889 ◽

2021 ◽

pp. 135406612110338

Author(s):

Joanne Yao

Keyword(s):

International Relations ◽

20Th Century ◽

International Institutions ◽

Social Performance ◽

Early 20Th Century ◽

Antarctic Treaty ◽

The Antarctic ◽

International Status ◽

Antarctic Treaty System

The Antarctic Treaty System (ATS), created in 1959 to govern the southern continent, is often lauded as an illustration of science’s potential to inspire peaceful and rational International Relations. This article critically examines this optimistic view of science’s role in international politics by focusing on how science as a global hierarchical structure operated as a gatekeeper to an exclusive Antarctic club. I argue that in the early 20th century, the conduct of science in Antarctica was entwined with global and imperial hierarchies. As what Mattern and Zarakol call a broad hierarchy, science worked both as a civilized marker of international status as well as a social performance that legitimated actors’ imperial interests in Antarctica. The 1959 ATS relied on science as an existing broad hierarchy to enable competing states to achieve a functional bargain and ‘freeze’ sovereignty claims, whilst at the same time institutionalizing and reinforcing the legitimacy of science in maintaining international inequalities. In making this argument, I stress the role of formal international institutions in bridging our analysis of broad and functional hierarchies while also highlighting the importance of scientific hierarchies in constituting the current international order.

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Remote sensing of multiyear ice in the Antarctic

10.5194/dach2022-284 ◽

2021 ◽

Author(s):

Christian Melsheimer ◽

Gunnar Spreen

Keyword(s):

Time Series ◽

Sea Ice ◽

Global Climate ◽

Ice Cover ◽

Cold Season ◽

Arctic Sea Ice ◽

Weddell Sea ◽

Detailed Knowledge ◽

The Antarctic ◽

Multiyear Ice

The changing sea ice cover of polar seas is of key importance for the exchange of heat and moisture between atmosphere and ocean and hence for weather and climate, and in addition, the sea ice and its long-term changes are &#160;an indicator for global change. &#160;In order to properly understand and model the evolution of the sea ice cover and its interaction with the global climate system, we need detailed knowledge about sea ice, i.e., not only its extent, but also, e.g., its thickness and its type. We can broadly distinguish a few different sea ice types that have different dynamic and thermodynamic properties, namely: young ice (YI, thin/smooth new ice), first-year ice (FYI, formed during one cold season), and multiyear ice (MYI, which has survived at least one melt season). The&#160; latter is of particular interest as it is usually thicker than other ice types (thus, takes more time to melt), much less saline, and may accommodate a unique ecosystem. Sea ice types in the Antarctic, until recently, have not been monitored much because of the lack of appropriate remote&#160; sensing methods. While the Antarctic sea ice is greatly dominated by FYI, there are, nevertheless, considerable amounts of MYI, in particular in the Weddell Sea. We have recently adapted an algorithm for the detection of Arctic sea ice types for application in the Antarctic. The algorithm uses data from space-borne microwave radiometers and scatterometers as input. So far we have compiled a time series of daily Antarctic MYI data (and also an estimate of YI and FYI) data at a spatial resolution of 12.5 km, starting in 2013, but excluding the melt seasons when the algorithm does not work. Here give an overview of the data, showing, e.g., the quite large interannual variability of MYI and its evolution in the Weddell Sea, and discuss shortcomings of the algorithm and possible ways forward. The time series of daily Antarctic MYI data can in principle be extended backwards to the year 2000, when the used satellite data first became available, and with planned future satellite missions, it can be continued for years to come.

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Maintenance Role of a Glutathionyl-Hydroquinone Lyase (PcpF) in Pentachlorophenol Degradation by Sphingobium chlorophenolicum ATCC 39723

Journal of Bacteriology ◽

10.1128/jb.00489-08 ◽

2008 ◽

Vol 190 (23) ◽

pp. 7595-7600 ◽

Cited By ~ 21

Author(s):

Yan Huang ◽

Randy Xun ◽

Guanjun Chen ◽

Luying Xun

Keyword(s):

Degradation Rate ◽

Tricarboxylic Acid Cycle ◽

Degradation Pathway ◽

Tricarboxylic Acid ◽

Metabolic Intermediate ◽

Reductive Dehalogenase ◽

Cell Extracts ◽

Toxic Pollutant ◽

Sphingobium Chlorophenolicum

ABSTRACT Pentachlorophenol (PCP) is a toxic pollutant. Its biodegradation has been extensively studied in Sphingobium chlorophenolicum ATCC 39723. All enzymes required to convert PCP to a common metabolic intermediate before entering the tricarboxylic acid cycle have been characterized. One of the enzymes is tetrachloro-p-hydroquinone (TeCH) reductive dehalogenase (PcpC), which is a glutathione (GSH) S-transferase (GST). PcpC catalyzes the GSH-dependent conversion of TeCH to trichloro-p-hydroquinone (TriCH) and then to dichloro-p-hydroquinone (DiCH) in the PCP degradation pathway. PcpC is susceptible to oxidative damage, and the damaged PcpC produces glutathionyl (GS) conjugates, GS-TriCH and GS-DiCH, which cannot be further metabolized by PcpC. The fate and effect of GS-hydroquinone conjugates were unknown. A putative GST gene (pcpF) is located next to pcpC on the bacterial chromosome. The pcpF gene was cloned, and the recombinant PcpF was purified. The purified PcpF was able to convert GS-TriCH and GS-DiCH conjugates to TriCH and DiCH, respectively. The GS-hydroquinone lyase reactions catalyzed by PcpF are rather unusual for a GST. The disruption of pcpF in S. chlorophenolicum made the mutant lose the GS-hydroquinone lyase activities in the cell extracts. The mutant became more sensitive to PCP toxicity and had a significantly decreased PCP degradation rate, likely due to the accumulation of the GS-hydroquinone conjugates inside the cell. Thus, PcpF played a maintenance role in PCP degradation and converted the GS-hydroquinone conjugates back to the intermediates of the PCP degradation pathway.

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Evolution in the cold

Antarctic Science ◽

10.1017/s0954102000000316 ◽

2000 ◽

Vol 12 (3) ◽

pp. 257-257 ◽

Cited By ~ 6

Author(s):

Andrew Clarke

Keyword(s):

Evolutionary Biology ◽

Antarctic Fish ◽

The Arctic ◽

Polar Regions ◽

Evolutionary Studies ◽

Adaptive Radiations ◽

The Antarctic ◽

The Impact ◽

Insight Into

Theodosius Dobzhansky once remarked that nothing in biology makes sense other than in the light of evolution, thereby emphasising the central role of evolutionary studies in providing the theoretical context for all of biology. It is perhaps surprising then that evolutionary biology has played such a small role to date in Antarctic science. This is particularly so when it is recognised that the polar regions provide us with an unrivalled laboratory within which to undertake evolutionary studies. The Antarctic exhibits one of the classic examples of a resistance adaptation (antifreeze peptides and glycopeptides, first described from Antarctic fish), and provides textbook examples of adaptive radiations (for example amphipod crustaceans and notothenioid fish). The land is still largely in the grip of major glaciation, and the once rich terrestrial floras and faunas of Cenozoic Gondwana are now highly depauperate and confined to relatively small patches of habitat, often extremely isolated from other such patches. Unlike the Arctic, where organisms are returning to newly deglaciated land from refugia on the continental landmasses to the south, recolonization of Antarctica has had to take place by the dispersal of propagules over vast distances. Antarctica thus offers an insight into the evolutionary responses of terrestrial floras and faunas to extreme climatic change unrivalled in the world. The sea forms a strong contrast to the land in that here the impact of climate appears to have been less severe, at least in as much as few elements of the fauna show convincing signs of having been completely eradicated.

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The Role of Chaperone-Mediated Autophagy in Hepatitis C Virus-Induced Pathogenesis

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.796664 ◽

2021 ◽

Vol 11 ◽

Author(s):

Chieko Matsui ◽

Putu Yuliandari ◽

Lin Deng ◽

Takayuki Abe ◽

Ikuo Shoji

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Degradation Process ◽

Degradation Pathway ◽

Hepatocyte Nuclear Factor ◽

Selective Degradation ◽

Substrate Protein ◽

Hepatocyte Nuclear Factor 1Α ◽

Chaperone Mediated Autophagy

Lysosome incorporate and degrade proteins in a process known as autophagy. There are three types of autophagy; macroautophagy, microautophagy, and chaperone-mediated autophagy (CMA). Although autophagy is considered a nonselective degradation process, CMA is known as a selective degradation pathway. All proteins internalized in the lysosome via CMA contain a pentapeptide KFERQ-motif, also known as a CMA-targeting motif, which is necessary for selectivity. CMA directly delivers a substrate protein into the lysosome lumen using the cytosolic chaperone HSC70 and the lysosomal receptor LAMP-2A for degradation. Hepatitis C virus (HCV) NS5A protein interacts with hepatocyte-nuclear factor 1α (HNF-1α) together with HSC70 and promotes the lysosomal degradation of HNF-1α via CMA, resulting in HCV-induced pathogenesis. HCV NS5A promotes recruitment of HSC70 to the substrate protein HNF-1α. HCV NS5A plays a crucial role in HCV-induced CMA. Further investigations of HCV NS5A-interacting proteins containing CMA-targeting motifs may help to elucidate HCV-induced pathogenesis.

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The Plio-Pleistocene climatic evolution as a consequence of orbital forcing on the carbon cycle

10.5194/cp-2017-3 ◽

2017 ◽

Author(s):

Didier Paillard

Keyword(s):

Carbon Cycle ◽

Ice Core ◽

Climate Science ◽

Atmospheric Concentration ◽

Sources And Sinks ◽

Climatic Evolution ◽

Astronomical Forcing ◽

The Antarctic ◽

Simple Dynamical Model

Abstract. Since the discovery of ice ages in the XIXth century, a central question of climate science has been to understand the respective role of the astronomical forcing and of greenhouse gases, in particular changes in the atmospheric concentration of carbon dioxide. Glacial-interglacial cycles have been shown to be paced by the astronomy with a dominant periodicity of 100 ka over the last million years, and a periodicity of 41 ka between roughly 1 and 3 million years before present (MyrBP). But the role and dynamics of the carbon cycle over the last 4 million years remain poorly understood. In particular, the transition into the Pleistocene about 2.8 MyrBP or the transition towards larger glaciations about 0.8 MyrBP (sometimes refered as the mid-pleistocene transition, or MPT) are not easily explained as direct consequences of the astronomical forcing. Some recent atmospheric CO2 reconstructions suggest slightly higher pCO2 levels before 1 MyrBP and a slow decrease over the last few million years (Bartoli et al., 2011; Seki et al., 2010). But the dynamics and the climatic role of the carbon cycle during the Plio-Pleistocene period remain unclear. Interestingly, the d13C marine records provide some critical information on the evolution of sources and sinks of carbon. In particular, a clear 400-kyr oscillation has been found at many different time periods and appears to be a robust feature of the carbon cycle throughout at least the last 100 Myr (eg. Paillard and Donnadieu, 2014). This oscillation is also visible over the last 4 Myr but its relationship with the eccentricity appears less obvious, with the occurrence of longer cycles at the end of the record, and a periodicity which therefore appears shifted towards 500-kyr (cf. Wang et al., 2004). In the following we present a simple dynamical model that provides an explanation for these carbon cycle variations, and how they relate to the climatic evolution over the last 4 Myr. It also gives an explanation for the lowest pCO2 values observed in the Antarctic ice core around 600–700 kyrBP. More generally, the model predicts a two-step decrease in pCO2 levels associated with the 2.4 Myr modulation of the eccentricity forcing. These two steps occur respectively at the Plio-Pleistocene transition and at the MPT, which strongly suggests that these transitions are astronomicaly forced through the dynamics of the carbon cycle.

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The role of fish in the Antarctic marine food web: differences between inshore and offshore waters in the southern Scotia Arc and west Antarctic Peninsula

Antarctic Science ◽

10.1017/s0954102002000111 ◽

2002 ◽

Vol 14 (4) ◽

pp. 293-309 ◽

Cited By ~ 90

Author(s):

ESTEBAN BARRERA-ORO

Keyword(s):

Food Web ◽

Antarctic Peninsula ◽

Demersal Fish ◽

Pelagic Fish ◽

West Antarctic ◽

Antarctic Marine ◽

Scotia Arc ◽

West Antarctic Peninsula ◽

The Antarctic

The role of fish in the Antarctic food web in inshore and offshore waters is analysed, taking as an example the coastal marine communities of the southern Scotia Arc (South Orkney Islands and South Shetland Islands) and the west Antarctic Peninsula. Inshore, the ecological role of demersal fish is more important than that of krill. There, demersal fish are major consumers of benthos and also feed on zooplankton (mainly krill in summer). They are links between lower and upper levels of the food web and are common prey of other fish, birds and seals. Offshore, demersal fish depend less on benthos and feed more on zooplankton (mainly krill) and nekton, and are less accessible as prey of birds and seals. There, pelagic fish (especially lantern fish) are more abundant than inshore and play an important role in the energy flow from macrozooplankton to higher trophic levels (seabirds and seals). Through the higher fish predators, energy is transferred to land in the form of fish remains, pellets (birds), regurgitation and faeces (birds and seals). However, in the general context of the Antarctic marine ecosystem, krill (Euphausia superba) plays the central role in the food web because it is the main food source in terms of biomass for most of the high level predators from demersal fish up to whales. This has no obvious equivalent in other marine ecosystems. In Antarctic offshore coastal and oceanic waters the greatest proportion of energy from the ecosystem is transferred to land directly through krill consumers, such as flying birds, penguins, and seals. Beside krill, the populations of fish in the Antarctic Ocean are the second most important element for higher predators, in particular the energy-rich pelagic Myctophidae in open waters and the pelagic Antarctic silver fish (Pleuragramma antarcticum) in the high Antarctic zone. Although the occurrence of these pelagic fish inshore has been poorly documented, their abundance in neritic waters could be higher than previously believed.

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