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來源:科學網 發布時間:2019/1/9 15:10:13
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《科學》論文導讀:2019年1月4日

 

 
 
古生物學Paleontology
 
 
 
 
An elephant-sized Late Triassic synapsid with erect limbs
 
體型和大象一樣且擁有直立四肢的晚三疊世單孔亞綱動物
 
▲ 作者:Tomasz Sulej, Grzegorz Nied?wiedzki
 
▲ 鏈接:
 
http://science.sciencemag.org/content/363/6422/78
 
 
 
▲ 摘要:
 
這里,我們描述了來自波蘭晚三疊世的二齒獸Lisowicia bojani。
 
 
 
這是一種巨型單孔亞綱動物,擁有看似直立的適于行走的四肢。據估測,其四肢長度超過4.5米,高度為2.6米,體重達9噸。
 
 
 
Lisowicia是最年輕的無可爭議的二齒獸,并且是來自三疊世的最大的非恐龍陸地四足動物。停止生長線的缺失和四肢骨頭被高度改造的皮質表明了永久的快速生長,并且讓人想到恐龍和哺乳動物。
 
 
 
Lisowicia的發現顛覆了三疊世巨型動物群輻射局限于恐龍這一既有畫面,并且證實,干群哺乳動物能達到哺乳動物進化史上直到最末期始新世才再次出現的體型。
 
 
 
▲ Abstract
 
Here, we describe the dicynodont Lisowicia bojani, from the Late Triassic of Poland, a gigantic synapsid with seemingly upright subcursorial limbs that reached an estimated length of more than 4.5 meters, height of 2.6 meters, and body mass of 9 tons. Lisowicia is the youngest undisputed dicynodont and the largest nondinosaurian terrestrial tetrapod from the Triassic. The lack of lines of arrested growth and the highly remodeled cortex of its limb bones suggest permanently rapid growth and recalls that of dinosaurs and mammals. The discovery of Lisowicia overturns the established picture of the Triassic megaherbivore radiation as a phenomenon restricted to dinosaurs and shows that stem-group mammals were capable of reaching body sizes that were not attained again in mammalian evolution untilthe latest Eocene.
 
 
 
 
氣候科學Climate Science
 
 
 
 
The Little Ice Age and 20th-century deep Pacific cooling
 
小冰河期和20世紀太平洋深處變冷
 
▲ 作者:G. Gebbie, P. Huybers
 
▲ 鏈接:
 
http://science.sciencemag.org/content/363/6422/70
 
 
 
▲ 摘要:
 
替代記錄顯示,在現代人為變暖開始前,全球持續的變冷一直從中世紀暖期延伸到小冰河期。海洋的長久記憶表明,這些歷史上的海洋表面異常同持續進行的深海溫度調整存在關聯。
 
 
 
將海洋模型同現代和古海洋數據結合,產生了這樣一種預測,即太平洋深處仍在適應進入小冰河期的變冷,而表面海洋和大西洋深處的溫度趨勢反映了現代變暖。
 
 
 
這一預測被19世紀70年代英國皇家海軍“挑戰者”號考察和現代水文學之間得以確認的溫度變化證實。
 
 
 
▲ Abstract
 
Proxy records show that before the onset of modern anthropogenic warming, globally coherent cooling occurred from the Medieval Warm Period to the Little Ice Age. The long memory of the ocean suggests that these historical surface anomalies are associated with ongoing deep-ocean temperature adjustments. Combining an ocean model with modern and paleoceanographic data leads to a prediction that the deep Pacific is still adjusting to the cooling going into the Little Ice Age, whereas temperature trends in the surface ocean and deep Atlantic reflect modern warming. This prediction is corroborated by temperature changes identified between the HMS Challenger expedition of the 1870s and modern hydrography.
 
 
 
 
物理學Physics
 
 
 
 
Laser cooling of ions in a neutral plasma
 
中性等離子體中離子的激光冷卻
 
▲ 作者:Thomas K. Langin, Grant M. Gorman, Thomas C. Killian
 
▲ 鏈接:
 
http://science.sciencemag.org/content/363/6422/61
 
 
 
▲ 摘要:
 
中性等離子體的激光冷卻是一項挑戰性任務,因為高溫通常和等離子體狀態相關。
 
 
 
通過利用超冷原子氣體光化電離創建的超冷中性等離子體,我們避開了這一障礙并且展示了中性等離子體中離子的激光冷卻。在135微秒的冷卻后,我們觀察到離子溫度下降至原來的1/4,最低達到50毫開爾文。
 
 
 
這推動中性等離子體的實驗室研究向強耦合領域進一步深入,并且超越計算輸運性質的現有動力論的有效性限制。
 
 
 
▲ Abstract
 
Laser cooling ofa neutral plasma is a challenging task because of the high temperatures typically associated with the plasma state. By using an ultra cold neutral plasma created by photoionization of an ultracold atomic gas, we avoid this obstacle and demonstrate laser cooling of ions in a neutral plasma. After 135 microseconds of cooling, we observed a reduction in ion temperature by up to a factor of four, with the temperature reaching as low as 50 millikelvin. This pushes laboratory studies of neutral plasmas deeper into the strongly coupled regime, beyond the limits of validity of current kinetic theories forcalculating transport properties.
 
 
 
 
植物學Botany
 
 
 
 
Synthetic glycolate metabolism pathwaysstimulate crop growth and productivity in the field
 
合成甘醇酸代謝通路刺激田間作物生長和生產力
 
▲ 作者:Paul F. South, Amanda P. Cavanagh, Helen W. Liu, et al
 
▲ 鏈接:
 
http://science.sciencemag.org/content/363/6422/eaat9077
 
 
 
▲ 摘要:
 
碳三植物需要光呼吸代謝有毒甘醇酸。取決于生長溫度,光呼吸可將碳三植物的產量降低20%~50%。
 
 
 
受早期工作啟發,我們將煙草葉綠體安裝到合成甘醇酸代謝通路中。這些通路被認為比天然途徑更加高效。抑制乙醇酸從葉綠體中輸出,使經過合成途徑的通量實現了最大化。
 
 
 
接受測試的合成通路使光合作用量子產率提高了20%。在可重現的田間試驗中,眾多純合系使生物生產力增加了40%多。
 
 
 
這些結果證明,將替代性甘醇酸代謝通路安裝到作物葉綠體中同時抑制甘醇酸從天然通路的輸出,可在農業田間條件下驅動碳三作物產量增加。
 
 
 
▲ Abstract
 
Photorespiration is required in C3 plants to metabolize toxic glycolate. Depending on growing temperatures, photorespiration can reduce yields by 20 to 50% in C3 crops. Inspired by earlier work, we installed into tobacco chloroplasts synthetic glycolate metabolic pathways that are thought to be more efficient than the native pathway. Flux through the synthetic pathways was maximized by inhibiting glycolate export from the chloroplast. The synthetic pathways tested improved photo synthetic quantum yield by 20%. Numerous homozygous transgenic lines increased biomass productivity by >40% in replicated field trials. These results show that engineering alternative glycolate metabolic pathways into crop chloroplasts while inhibiting glycolate export into the native pathway candrive increases in C3 crop yield under agricultural field conditions.
 
 
 
 
生理學Physiology
 
 
 
 
Synaptotagmin-3 drives AMPA receptor endocytosis, depression of synapse strength, and forgetting
 
突觸結合蛋白3驅動AMPA受體內吞、突觸強度抑制和忘記
 
▲ 作者:Ankit Awasthi, Binu Ramachandran, Saheeb Ahmed, et al
 
▲ 鏈接:
 
http://science.sciencemag.org/content/363/6422/eaav1483
 
 
 
▲ 摘要:
 
忘記很重要。沒有它,在變化環境中所獲記憶的相對重要性便會失去。
 
 
 
我們發現,突觸結合蛋白3(Syt3)定位于突觸后內吞作用區域,并且移除來自突觸等離子體膜的AMPA受體,以應對刺激。
 
 
 
AMPA受體內化、長時程抑制(LTD)以及突觸強度長時程增強(LTP)的衰退需要Syt3的鈣敏感,并且通過Syt3敲除而消失。
 
 
 
在空間記憶任務中,Syt3被敲除的小鼠可正常學習,但表現出忘記的缺失。擾亂野生型背景中的Syt3:GluA2結合模擬了LTP衰退和忘記的缺失,而這些效應在Syt3敲除背景中被阻止。
 
 
 
我們的發現提供了Syt3內化AMPA受體以抑制突觸強度并且促進忘記的分子機制。
 
 
 
▲ Abstract
 
Forgetting is important. Without it, the relative importance of acquired memories in a changing environment is lost. We discovered that synaptotagmin-3 (Syt3) localizes to postsynaptic endocytic zones and removes AMPA receptors from synaptic plasma membranes in response to stimulation. AMPA receptor internalization, long-term depression (LTD), and decay of long-termpotentiation (LTP) of synaptic strength required calcium-sensing by Syt3 andwere abolished through Syt3 knockout. In spatial memory tasks, mice in which Syt3 was knocked out learned normally but exhibited a lack of forgetting. Disrupting Syt3:GluA2 binding in a wild-type background mimicked the lack ofLTP decay and lack of forgetting, and these effects were occluded in the Syt3 knockout background. Our findings provide evidence for a molecular mechanism in which Syt3 internalizes AMPA receptors to depress synaptic strength and promote forgetting.
 
 
 
DNA fragility in the parallel evolution of pelvic reduction in stickleback fish
 
棘魚骨盆喪失平行進化中的DNA脆弱性
 
▲ 作者:Kathleen T. Xie, Guliang Wang, Abbey C. Thompson, et al
 
▲ 鏈接:
 
http://science.sciencemag.org/content/363/6422/81
 
 
 
▲ 摘要:
 
進化產生了異常多樣的生命形式,但很多特征重復進化,而其中的機制仍未被充分理解。
 
 
 
重復進化的一個經典例子是棘魚骨盆后鰭的喪失。重復的骨盆喪失映射到Pitx1基因這個骨盆增強子的反復刪除。
 
 
 
這里,我們確認了導致這些重復刪除的分子特征。Pitx1增強子序列形成體外替代性DNA結構,并且增加了體外的雙鏈斷裂和刪除。增強子突變性取決于DNA復制方向,并且由TG-二核苷酸引發。
 
 
 
模型顯示,增加的突變率能影響同棘魚和人類相關的人口統計學條件下的進化。因此,DNA脆弱性或有助于解釋為何相同位點通常在平行適應性進化中被重復利用。
 
 
 
▲ Abstract
 
Evolution generates a remarkable breadth of living forms, but many traits evolve repeatedly, by mechanisms that are still poorly understood. A classic exampleof repeated evolution is the loss of pelvic hindfins in stickleback fish (Gasterosteus aculeatus). Repeated pelvic loss maps to recurrent deletions of apelvic enhancer of the Pitx1 gene. Here, we identify molecular features contributing to these recurrent deletions. Pitx1 enhancer sequences form alternative DNA structures in vitro and increase double-strand breaks anddeletions in vivo. Enhancer mutability depends on DNA replication direction and is caused by TG-dinucleotide repeats. Modeling shows that elevated mutation rates can influence evolution under demographic conditions relevant for sticklebacks and humans. DNA fragility may thus help explain why the same lociare often used repeatedly during parallel adaptive evolution.
 
 
 
A collicular visual cortex: Neocortical space for an ancient midbrain visual structure
 
丘視覺皮層:古老中腦視覺結構的新皮層空間
 
▲ 作者:Riccardo Beltramo, Massimo Scanziani
 
▲ 鏈接:
 
http://science.sciencemag.org/content/363/6422/64
 
 
 
▲ 摘要:
 
大腦皮層中的視覺響應被認為依賴于向初級視皮層(V1)的膝狀體輸入。
 
 
 
的確,V1損傷實質性地降低了通過皮層的視覺響應。視覺信息還通過上丘(SC)進入皮層,但這一輸入對于皮層中視覺響應的功能還不太清楚。
 
 
 
SC損傷對大腦皮層視覺響應的影響小于V1損傷,同時似乎沒有視覺皮質區域完全依賴于SC輸入。
 
 
 
我們證實,小鼠大腦側視覺皮質區的視覺響應不依賴于V1,并且一旦SC靜默,便被廢除。這一區域在識別移動物體方面的表現超過V1。
 
 
 
▲ Abstract
 
Visual responses in the cerebral cortex are believed to rely on the geniculate input to the primary visual cortex (V1). Indeed, V1 lesions substantially reduce visual responses through out the cortex. Visual information enters the cortex also through the superior colliculus (SC), but the function of this input on visual responses in the cortex is less clear. SC lesions affect cortical visual responses less than V1 lesions, and no visual cortical area appears to entirely rely on SC inputs. We show that visual responses in a mouse lateral visual cortical area called the postrhinal cortex are independent of V1 and are abolished upon silencing of the SC. This area out performs V1 in discriminating moving objects.
 
 
 
 
健康Health
 
 
 
 
Metagenomic sequencing at the epicenter of the Nigeria 2018 Lassa fever outbreak
 
尼日利亞2018年拉沙熱疫情爆發中心的宏基因組測序
 
▲ 作者:L. E. Kafetzopoulou, S. T. Pullan, P. Lemey, et al
 
▲ 鏈接:
 
http://science.sciencemag.org/content/363/6422/74
 
 
 
▲ 摘要:
 
2018年尼日利亞拉沙熱發病季經歷了有史以來最大規模的病例數攀升,從而引發了關于一種傳染率升高的病毒株現身的擔憂。
 
 
 
為了解病例數劇增背后的分子流行病學,我們首次在疫情爆發中心開展了直接來自患者樣本的宏基因組納米孔測序。這種方法受到目標病原體高度可變的基因組影響。
 
 
 
基因組數據和系統發育重建結果被立即傳送給尼日利亞當局和世界衛生組織,以便為公共衛生應急反應提供信息。
 
 
 
▲ Abstract
 
The 2018 Nigerian Lassa fever season saw the largest ever recorded upsurge of cases, raising concerns over the emergence of a strain with increased transmission rate. To understand the molecular epidemiology of this upsurge, we performed, for the first time at the epicenter of an unfolding outbreak, metagenomic nanopore sequencing directly from patient samples, an approach dictated by the highly variable genome of the target pathogen. Genomic data and phylogenetic reconstructions were communicated immediately to Nigerian authorities and the World Health Organization to inform the public health response.
 
 
 
(宗華)
 
 
 
 
 
 
 
 
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