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Ice retreat in Wilkes Basin of East Antarctica during a warm interglacial 期刊论文
NATURE, 2020, 583 (7817) : 554-+
作者:  T. Blackburn;  G. H. Edwards;  S. Tulaczyk;  M. Scudder;  G. Piccione;  B. Hallet;  N. McLean;  J. C. Zachos;  B. Cheney;  J. T. Babbe
收藏  |  浏览/下载：59/0  |  提交时间：2020/08/09

Uranium isotopes in subglacial precipitates from the Wilkes Basin of the East Antarctic Ice Sheet reveal ice retreat during a warm Pleistocene interglacial period about 400,000 years ago.


Efforts to improve sea level forecasting on a warming planet have focused on determining the temperature, sea level and extent of polar ice sheets during Earth'  s past interglacial warm periods(1-3). About 400,000 years ago, during the interglacial period known as Marine Isotopic Stage 11 (MIS11), the global temperature was 1 to 2 degrees Celsius greater(2)and sea level was 6 to 13 metres higher(1,3). Sea level estimates in excess of about 10 metres, however, have been discounted because these require a contribution from the East Antarctic Ice Sheet(3), which has been argued to have remained stable for millions of years before and includes MIS11(4,5). Here we show how the evolution of(234)U enrichment within the subglacial waters of East Antarctica recorded the ice sheet'  s response to MIS11 warming. Within the Wilkes Basin, subglacial chemical precipitates of opal and calcite record accumulation of(234)U (the product of rock-water contact within an isolated subglacial reservoir) up to 20 times higher than that found in marine waters. The timescales of(234)U enrichment place the inception of this reservoir at MIS11. Informed by the(234)U cycling observed in the Laurentide Ice Sheet, where(234)U accumulated during periods of ice stability(6)and was flushed to global oceans in response to deglaciation(7), we interpret our East Antarctic dataset to represent ice loss within the Wilkes Basin at MIS11. The(234)U accumulation within the Wilkes Basin is also observed in the McMurdo Dry Valleys brines(8-10), indicating(11)that the brine originated beneath the adjacent East Antarctic Ice Sheet. The marine origin of brine salts(10)and bacteria(12)implies that MIS11 ice loss was coupled with marine flooding. Collectively, these data indicate that during one of the warmest Pleistocene interglacials, the ice sheet margin at the Wilkes Basin retreated to near the precipitate location, about 700 kilometres inland from the current position of the ice margin, which-assuming current ice volumes-would have contributed about 3 to 4 metres(13)to global sea levels.


  
Isolation of an archaeon at the prokaryote-eukaryote interface 期刊论文
NATURE, 2020, 577 (7791) : 519-+
作者:  Imachi, Hiroyuki;  Nobu, Masaru K.;  Nakahara, Nozomi;  Morono, Yuki;  Ogawara, Miyuki;  Takaki, Yoshihiro;  Takano, Yoshinori;  Uematsu, Katsuyuki;  Ikuta, Tetsuro;  Ito, Motoo;  Matsui, Yohei;  Miyazaki, Masayuki;  Murata, Kazuyoshi;  Saito, Yumi;  Sakai, Sanae;  Song, Chihong;  Tasumi, Eiji;  Yamanaka, Yuko;  Yamaguchi, Takashi;  Kamagata, Yoichi;  Tamaki, Hideyuki;  Takai, Ken
收藏  |  浏览/下载：23/0  |  提交时间：2020/07/03

The origin of eukaryotes remains unclear(1-4). Current data suggest that eukaryotes may have emerged from an archaeal lineage known as '  Asgard'  archaea(5,6). Despite the eukaryote-like genomic features that are found in these archaea, the evolutionary transition from archaea to eukaryotes remains unclear, owing to the lack of cultured representatives and corresponding physiological insights. Here we report the decade-long isolation of an Asgard archaeon related to Lokiarchaeota from deep marine sediment. The archaeon-'  Candidatus Prometheoarchaeum syntrophicum'  strain MK-D1-is an anaerobic, extremely slow-growing, small coccus (around 550 nm in diameter) that degrades amino acids through syntrophy. Although eukaryote-like intracellular complexes have been proposed for Asgard archaea(6), the isolate has no visible organelle-like structure. Instead, Ca. P. syntrophicum is morphologically complex and has unique protrusions that are long and often branching. On the basis of the available data obtained from cultivation and genomics, and reasoned interpretations of the existing literature, we propose a hypothetical model for eukaryogenesis, termed the entangle-engulf-endogenize (also known as E-3) model.


Isolation and characterization of an archaeon that is most closely related to eukaryotes reveals insights into how eukaryotes may have evolved from prokaryotes.


  
Is salinity an obstacle for biological invasions? 期刊论文
GLOBAL CHANGE BIOLOGY, 2018, 24 (6) : 2708-2720
作者:  Paiva, Filipa;  Barco, Andrea;  Chen, Yiyong;  Mirzajani, Alireza;  Chan, Farrah T.;  Lauringson, Velda;  Baltazar-Soares, Miguel;  Zhan, Aibin;  Bailey, Sarah A.;  Javidpour, Jamileh;  Briski, Elizabeta
收藏  |  浏览/下载：21/0  |  提交时间：2019/04/09
freshwater origin  Gammaroidea  marine origin  nonindigenous species  Ponto-Caspian species  salinity tolerance