scholarly journals Metabolomics of Dry Versus Reanimated Antarctic Lichen-Dominated Endolithic Communities

Life ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 96
Author(s):  
Giuseppina Fanelli ◽  
Claudia Coleine ◽  
Federica Gevi ◽  
Silvano Onofri ◽  
Laura Selbmann ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Critical Role ◽  
Tca Cycle ◽  
Special Focus ◽  
Eukaryotic Diversity ◽  
The North ◽  
Dry Conditions ◽  
Ecological Importance ◽  
The Antarctic ◽  
Endolithic Communities

Cryptoendolithic communities are almost the sole life form in the ice-free areas of the Antarctic desert, encompassing among the most extreme-tolerant organisms known on Earth that still assure ecosystems functioning, regulating nutrient and biogeochemical cycles under conditions accounted as incompatible with active life. If high-throughput sequencing based studies are unravelling prokaryotic and eukaryotic diversity, they are not yet characterized in terms of stress adaptations and responses, despite their paramount ecological importance. In this study, we compared the responses of Antarctic endolithic communities, with special focus on fungi, both under dry conditions (i.e., when dormant), and after reanimation by wetting, light, and optimal temperature (15 °C). We found that several metabolites were differently expressed in reanimated opposite sun exposed communities, suggesting a critical role in their success. In particular, the saccharopine pathway was up-regulated in the north surface, while the spermine/spermidine pathway was significantly down-regulated in the shaded exposed communities. The carnitine-dependent pathway is up-regulated in south-exposed reanimated samples, indicating the preferential involvement of the B-oxidation for the functioning of TCA cycle. The role of these metabolites in the performance of the communities is discussed herein.

scholarly journals Fungi in the Antarctic cryosphere: using DNA metabarcoding to reveal fungal diversity in glacial ice from the Antarctic Peninsula region

2021 ◽  
Author(s):  
Graciéle de Menezes ◽  
Paulo Câmara ◽  
Otávio Pinto ◽  
Peter Convey ◽  
Micheline Carvalho-Silva ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Fungal Diversity ◽  
High Throughput Sequencing ◽  
South Shetland Islands ◽  
Glacial Ice ◽  
North West ◽  
The North ◽  
Animal Pathogens ◽  
Dna Metabarcoding ◽  
The Antarctic

Abstract We assessed fungal diversity present in glacial of the Antarctic Peninsula using DNA metabarcoding through high throughput sequencing (HTS). We detected a total of 353,879 fungal DNA reads, representing 94 genera and 184 taxa, in glacial ice fragments obtained from seven sites in the north-west Antarctic Peninsula and South Shetland Islands. The phylum Ascomycota dominated the sequence diversity, followed by Basidiomycota and Mortierellomycota. Penicillium sp., Cladosporium sp., Penicillium atrovenetum, Epicoccum nigrum, Pseudogymnoascus sp. 1, Pseudogymnoascus sp. 2, Phaeosphaeriaceae sp. and Xylaria grammica were the most dominant taxa, respectively. However, the majority of the fungal diversity comprised taxa of rare and intermediate relative abundance, predominately known mesophilic fungi. High indices of diversity and richness were calculated, along with moderate index of dominance, which varied among the different sampling sites. Only 26 (14%) of the total fungal taxa detected were present at all sampling sites. The identified diversity was dominated by saprophytic taxa, followed by known plant and animal pathogens and a low number of symbiotic fungi. Our data suggest that Antarctic glacial ice may represent a hotspot of previously unreported fungal diversity; however, further studies are required to integrate HTS and culture approaches to confirm viability of the taxa detected.

scholarly journals Estimating and Monitoring Land Surface Phenology in Rangelands: A Review of Progress and Challenges

2021 ◽  
Vol 13 (11) ◽  
pp. 2060
Author(s):  
Trylee Nyasha Matongera ◽  
Onisimo Mutanga ◽  
Mbulisi Sibanda ◽  
John Odindi
Keyword(s):  
Land Surface ◽  
Vegetation Index ◽  
Critical Role ◽  
Spectral Characteristics ◽  
Vegetation Indices ◽  
Machine Learning Algorithms ◽  
Special Focus ◽  
Land Surface Phenology ◽  
Spectral Vegetation Indices ◽  
Satellite Sensors

Land surface phenology (LSP) has been extensively explored from global archives of satellite observations to track and monitor the seasonality of rangeland ecosystems in response to climate change. Long term monitoring of LSP provides large potential for the evaluation of interactions and feedbacks between climate and vegetation. With a special focus on the rangeland ecosystems, the paper reviews the progress, challenges and emerging opportunities in LSP while identifying possible gaps that could be explored in future. Specifically, the paper traces the evolution of satellite sensors and interrogates their properties as well as the associated indices and algorithms in estimating and monitoring LSP in productive rangelands. Findings from the literature revealed that the spectral characteristics of the early satellite sensors such as Landsat, AVHRR and MODIS played a critical role in the development of spectral vegetation indices that have been widely used in LSP applications. The normalized difference vegetation index (NDVI) pioneered LSP investigations, and most other spectral vegetation indices were primarily developed to address the weaknesses and shortcomings of the NDVI. New indices continue to be developed based on recent sensors such as Sentinel-2 that are characterized by unique spectral signatures and fine spatial resolutions, and their successful usage is catalyzed with the development of cutting-edge algorithms for modeling the LSP profiles. In this regard, the paper has documented several LSP algorithms that are designed to provide data smoothing, gap filling and LSP metrics retrieval methods in a single environment. In the future, the development of machine learning algorithms that can effectively model and characterize the phenological cycles of vegetation would help to unlock the value of LSP information in the rangeland monitoring and management process. Precisely, deep learning presents an opportunity to further develop robust software packages such as the decomposition and analysis of time series (DATimeS) with the abundance of data processing tools and techniques that can be used to better characterize the phenological cycles of vegetation in rangeland ecosystems.

A multi-proxy reconstruction of climate during the late-Pleistocene to early Holocene transition in the northeastern, USA

2021 ◽  
pp. 1-17
Author(s):  
Laurie D. Grigg ◽  
Kevin J. Engle ◽  
Alison J. Smith ◽  
Bryan N. Shuman ◽  
Maximilian B. Mandl
Keyword(s):  
Late Pleistocene ◽  
Climatic Variability ◽  
Warming Trend ◽  
Early Holocene ◽  
Individual Species ◽  
Environmental Preferences ◽  
The North ◽  
Show Evidence ◽  
Dry Conditions ◽  
Components Analysis

Abstract A multiproxy record from Twin Ponds, VT, is used to reconstruct climatic variability during the late Pleistocene to early Holocene transition. Pollen, ostracodes, δ18O, and lithologic records from 13.5 to 9.0 cal ka BP are presented. Pollen- and ostracode-inferred climatic reconstructions are based on individual species’ environmental preferences and the modern analog technique. Principal components analysis of all proxies highlights the overall warming trend and centennial-scale climatic variability. During the Younger Dryas cooling event (YD), multiple proxies show evidence for cold winter conditions and increasing seasonality after 12.5 cal ka BP. The early Holocene shows an initial phase of rapid warming with a brief cold interval at 11.5 cal ka BP, followed by a more gradual warming; a cool, wet period from 11.2 to 10.8 cal ka BP; and cool, dry conditions from 10.8 to 10.2 cal ka BP. The record ends with steady warming and increasing moisture. Post-YD climatic variability has been observed at other sites in the northeastern United States and points to continued instability in the North Atlantic during the final phases of deglaciation.

The Role of Oscillating Southern Hemisphere Westerly Winds: Global Ocean Circulation

2020 ◽  
Vol 33 (6) ◽  
pp. 2111-2130
Author(s):  
Woo Geun Cheon ◽  
Jong-Seong Kug
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
North Pacific ◽  
Global Ocean ◽  
The North ◽  
Westerly Winds ◽  
The North Atlantic ◽  
Global Ocean Circulation ◽  
The Antarctic ◽  
The North Pacific

AbstractIn the framework of a sea ice–ocean general circulation model coupled to an energy balance atmospheric model, an intensity oscillation of Southern Hemisphere (SH) westerly winds affects the global ocean circulation via not only the buoyancy-driven teleconnection (BDT) mode but also the Ekman-driven teleconnection (EDT) mode. The BDT mode is activated by the SH air–sea ice–ocean interactions such as polynyas and oceanic convection. The ensuing variation in the Antarctic meridional overturning circulation (MOC) that is indicative of the Antarctic Bottom Water (AABW) formation exerts a significant influence on the abyssal circulation of the globe, particularly the Pacific. This controls the bipolar seesaw balance between deep and bottom waters at the equator. The EDT mode controlled by northward Ekman transport under the oscillating SH westerly winds generates a signal that propagates northward along the upper ocean and passes through the equator. The variation in the western boundary current (WBC) is much stronger in the North Atlantic than in the North Pacific, which appears to be associated with the relatively strong and persistent Mindanao Current (i.e., the southward flowing WBC of the North Pacific tropical gyre). The North Atlantic Deep Water (NADW) formation is controlled by salt advected northward by the North Atlantic WBC.

scholarly journals The Size of Diatoms II. Further Observations on Rhizosolenia styliformis (Brightwell)

1946 ◽  
Vol 26 (3) ◽  
pp. 271-284 ◽  
Author(s):  
R. S. Wimpenny
Keyword(s):  
North Sea ◽  
Indicator Species ◽  
Separate Species ◽  
Southern North Sea ◽  
Auxospore Formation ◽  
The North ◽  
The North Sea ◽  
Set Up ◽  
The Antarctic

1. Diameter measurements of Rhizosolenia styliformis from the Antarctic, the subtropical Atlantic and Pacific Oceans and from the North Sea and neighbouring waters have made it appear necessary to set up two varieties, oceanica and semispina, in addition to the type of the species R. styliformis. The type as I describe it has been called var. longispina by Hustedt, but elsewhere it has often been figured as the var. oceanica of this paper. Var. semispina is synonymous with the form represented by Karsten as R. semispina Hensen. It differs from R. semispina as drawn by Hensen and its synonym R. hebetata forma semispina Gran, but is thought likely to be linked by intermediates. If this is so R. hebetata may have to be extended to include and suppress R. styliformis, as var. semispina is linked to the type by intermediates. Var. oceanica has no intermediate forms and, if R. hebetata is to be extended, this variety should be established as a separate species.2. Var. oceanica is absent from the southern North Sea and appears to be an indicator species related to oceanic inflow.3. Auxospore formation was observed for the type in the southern North Sea in 1935 and biometric observations suggest that a period of 3-4 years elapsed between the production of auxospore generations in that area. Outside the southern North Sea for the type, measurements give no indication of auxospore generations occurring at intervals exceeding a year. While auxospore formation has been seen in var. oceanica from the Shetlands area samples of June 1935 and July 1938, this phenomenon has not been observed for var. semispina.

scholarly journals A Tocqueville For the North? André Siegfried and Canada

2005 ◽  
Vol 14 (1) ◽  
pp. 117-136 ◽  
Author(s):  
Sean Kennedy
Keyword(s):  
Critical Role ◽  
Second World War ◽  
Traditional Values ◽  
French Canada ◽  
The North ◽  
Vichy Regime ◽  
The Face ◽  
A Site ◽  
French National Identity ◽  
Second World

Abstract This paper argues that André Siegfried’s writings on Canada played a critical role in shaping his vision of French national identity. Siegfried’s studies of Canada have long been praised for their insight, but recent scholarship has emphasized his role in promoting both anti-Americanism and an exclusionary vision of what it meant to be French during the first half of the twentieth century. For Siegfried, Canada represented a site of managed contestation between British and French culture but also an early example of the deleterious effects of Americanization. His problematic view of French Canada as essentially conservative and unchanging in the face of such challenges reinforced his conviction that France itself should remain true to “traditional” values. The exclusionary implications of his ideas were most evident when Siegfried appeared to accommodate himself to the Vichy regime, but they also persisted after the Second World War.

scholarly journals Climate change in the western Antarctic Peninsula since 1945: observations and possible causes

1998 ◽  
Vol 27 ◽  
pp. 571-575 ◽  
Author(s):  
J. C. King ◽  
S. A. Harangozo
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
Antarctic Peninsula ◽  
The West ◽  
Sea Ice Extent ◽  
The North ◽  
Ultimate Cause ◽  
Temperature Records ◽  
High Level ◽  
The Antarctic

Temperature records from slations on the west roast of the Antarctic Peninsula show a very high level of interannual variability and, over the last 50 years, larger warming trends than are seen elsewhere in Antarctica. in this paper we investigate the role of atmospheric circulation variability and sea-ice extent variations in driving these changes. Owing to a lack of independent data, the reliability of Antarctic atmospheric analyses produced in the 1950s and 1960s cannot be readily established, but examination of the available data suggests that there has been an increase in the northerly component of the circulation over the Peninsula since the late 1950s. Few observations of sea-ice extent are available prior to 1973, but the limited data available indicate that the ice edge to the west of the Peninsula lay to the north of recently observed extremes during the very cold conditions prevailing in the late 1950s. The ultimate cause of the atmospheric-circulation changes remains to be determined and may lie outside the Antarctic region.

Holocene glacier history of northeastern Cordillera Darwin, southernmost South America (55°S)

2021 ◽  
pp. 1-16
Author(s):  
Scott A. Reynhout ◽  
Michael R. Kaplan ◽  
Esteban A. Sagredo ◽  
Juan Carlos Aravena ◽  
Rodrigo L. Soteres ◽  
...  
Keyword(s):  
South America ◽  
Last Millennium ◽  
Glacial History ◽  
Dry Period ◽  
The North ◽  
Southward Shift ◽  
History Of ◽  
Glacial Expansion ◽  
The Antarctic ◽  
Glacial Advance

Abstract In the Cordillera Darwin, southernmost South America, we used 10Be and 14C dating, dendrochronology, and historical observations to reconstruct the glacial history of the Dalla Vedova valley from deglacial time to the present. After deglacial recession into northeastern Darwin and Dalla Vedova, by ~16 ka, evidence indicates a glacial advance at ~13 ka coeval with the Antarctic Cold Reversal. The next robustly dated glacial expansion occurred at 870 ± 60 calendar yr ago (approximately AD 1150), followed by less-extensive dendrochronologically constrained advances from shortly before AD 1836 to the mid-twentieth century. Our record is consistent with most studies within the Cordillera Darwin that show that the Holocene glacial maximum occurred during the last millennium. This pattern contrasts with the extensive early- and mid-Holocene glacier expansions farther north in Patagonia; furthermore, an advance at 870 ± 60 yr ago may suggest out-of-phase glacial advances occurred within the Cordillera Darwin relative to Patagonia. We speculate that a southward shift of westerlies and associated climate regimes toward the southernmost tip of the continent, about 900–800 yr ago, provides a mechanism by which some glaciers advanced in the Cordillera Darwin during what is generally considered a warm and dry period to the north in Patagonia.

Sustainable Development in a Global Context: A Success or a Nuisance?

2015 ◽  
Vol 9 (1) ◽  
Author(s):  
Mohamed El-Kamel Bakari
Keyword(s):  
Sustainable Development ◽  
Trade Liberalization ◽  
Global Governance ◽  
Global Trade ◽  
Special Focus ◽  
Governance System ◽  
Global Context ◽  
The North ◽  
Similar Vein ◽  
The One

AbstractThis article argues that the evolution of, and challenges to, sustainable development cannot be understood completely outside its contemporary global context, consisting mainly of three interconnected spheres, i.e., the global governance system, the North-South debate, and global trade liberalization. As the boundaries of these three spheres get more and more blurred in a context of an intensifying globalization, the project of sustainable development is very often faced with obstacles that set back its evolution and might very well bring it to a halt. Above all, sustainable development is now caught in the crossfire between the push for exponential economic growth, on the one hand, and a compelling need to reverse catastrophic ecological threats and social exigencies, on the other. More often than not, the current structure and scope of global governance constitutes more of a hindrance than a help to the emerging paradigm of sustainable development. Accordingly, this article seeks to pinpoint the different challenges to the implementation of sustainable development in the field of global governance and to discuss to what extent these challenges are inherent in the structure and scope of this system. In a similar vein, this article examines and discusses the challenges to sustainability within two other highly interrelated spheres, namely global trade and the North-South politics. With this end in view, a special focus is placed throughout this paper on the interconnectedness of, and overlap between, these three global spheres and the determinant role played by the major actors therein.

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