来源:科学网 发布时间:2019/1/9 15:10:13
选择字号:
《科学》论文导读:2019年1月4日

 

 
 
古生物学Paleontology
 
 
 
 
An elephant-sized Late Triassic synapsid with erect limbs
 
体型和大象一样且拥有直立四肢的晚三叠世单孔亚纲动物
 
▲ 作者:Tomasz Sulej, Grzegorz Nied?wiedzki
 
▲ 链接:
 
http://science.sciencemag.org/content/363/6422/78
 
 
 
▲ 摘要:
 
这里,我们描述了来自波兰晚三叠世的二齿兽Lisowicia bojani。
 
 
 
这是一种巨型单孔亚纲动物,拥有看似直立的适于行走的四肢。据估测,其四肢长度超过4.5米,高度为2.6米,体重达9吨。
 
 
 
Lisowicia是最年轻的无可争议的二齿兽,并且是来自三叠世的最大的非恐龙陆地四足动物。停止生长线的缺失和四肢骨头被高度改造的皮质表明了永久的快速生长,并且让人想到恐龙和哺乳动物。
 
 
 
Lisowicia的发现颠覆了三叠世巨型动物群辐射局限于恐龙这一既有画面,并且证实,干群哺乳动物能达到哺乳动物进化史上直到最末期始新世才再次出现的体型。
 
 
 
▲ 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.
 
 
 
 
气候科学Climate Science
 
 
 
 
The Little Ice Age and 20th-century deep Pacific cooling
 
小冰河期和20世纪太平洋深处变冷
 
▲ 作者:G. Gebbie, P. Huybers
 
▲ 链接:
 
http://science.sciencemag.org/content/363/6422/70
 
 
 
▲ 摘要:
 
替代记录显示,在现代人为变暖开始前,全球持续的变冷一直从中世纪暖期延伸到小冰河期。海洋的长久记忆表明,这些历史上的海洋表面异常同持续进行的深海温度调整存在关联。
 
 
 
将海洋模型同现代和古海洋数据结合,产生了这样一种预测,即太平洋深处仍在适应进入小冰河期的变冷,而表面海洋和大西洋深处的温度趋势反映了现代变暖。
 
 
 
这一预测被19世纪70年代英国皇家海军“挑战者”号考察和现代水文学之间得以确认的温度变化证实。
 
 
 
▲ 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.
 
 
 
 
物理学Physics
 
 
 
 
Laser cooling of ions in a neutral plasma
 
中性等离子体中离子的激光冷却
 
▲ 作者:Thomas K. Langin, Grant M. Gorman, Thomas C. Killian
 
▲ 链接:
 
http://science.sciencemag.org/content/363/6422/61
 
 
 
▲ 摘要:
 
中性等离子体的激光冷却是一项挑战性任务,因为高温通常和等离子体状态相关。
 
 
 
通过利用超冷原子气体光化电离创建的超冷中性等离子体,我们避开了这一障碍并且展示了中性等离子体中离子的激光冷却。在135微秒的冷却后,我们观察到离子温度下降至原来的1/4,最低达到50毫开尔文。
 
 
 
这推动中性等离子体的实验室研究向强耦合领域进一步深入,并且超越计算输运性质的现有动力论的有效性限制。
 
 
 
▲ 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.
 
 
 
 
植物学Botany
 
 
 
 
Synthetic glycolate metabolism pathwaysstimulate crop growth and productivity in the field
 
合成甘醇酸代谢通路刺激田间作物生长和生产力
 
▲ 作者:Paul F. South, Amanda P. Cavanagh, Helen W. Liu, et al
 
▲ 链接:
 
http://science.sciencemag.org/content/363/6422/eaat9077
 
 
 
▲ 摘要:
 
碳三植物需要光呼吸代谢有毒甘醇酸。取决于生长温度,光呼吸可将碳三植物的产量降低20%~50%。
 
 
 
受早期工作启发,我们将烟草叶绿体安装到合成甘醇酸代谢通路中。这些通路被认为比天然途径更加高效。抑制乙醇酸从叶绿体中输出,使经过合成途径的通量实现了最大化。
 
 
 
接受测试的合成通路使光合作用量子产率提高了20%。在可重现的田间试验中,众多纯合系使生物生产力增加了40%多。
 
 
 
这些结果证明,将替代性甘醇酸代谢通路安装到作物叶绿体中同时抑制甘醇酸从天然通路的输出,可在农业田间条件下驱动碳三作物产量增加。
 
 
 
▲ 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.
 
 
 
 
生理学Physiology
 
 
 
 
Synaptotagmin-3 drives AMPA receptor endocytosis, depression of synapse strength, and forgetting
 
突触结合蛋白3驱动AMPA受体内吞、突触强度抑制和忘记
 
▲ 作者:Ankit Awasthi, Binu Ramachandran, Saheeb Ahmed, et al
 
▲ 链接:
 
http://science.sciencemag.org/content/363/6422/eaav1483
 
 
 
▲ 摘要:
 
忘记很重要。没有它,在变化环境中所获记忆的相对重要性便会失去。
 
 
 
我们发现,突触结合蛋白3(Syt3)定位于突触后内吞作用区域,并且移除来自突触等离子体膜的AMPA受体,以应对刺激。
 
 
 
AMPA受体内化、长时程抑制(LTD)以及突触强度长时程增强(LTP)的衰退需要Syt3的钙敏感,并且通过Syt3敲除而消失。
 
 
 
在空间记忆任务中,Syt3被敲除的小鼠可正常学习,但表现出忘记的缺失。扰乱野生型背景中的Syt3:GluA2结合模拟了LTP衰退和忘记的缺失,而这些效应在Syt3敲除背景中被阻止。
 
 
 
我们的发现提供了Syt3内化AMPA受体以抑制突触强度并且促进忘记的分子机制。
 
 
 
▲ 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
 
棘鱼骨盆丧失平行进化中的DNA脆弱性
 
▲ 作者:Kathleen T. Xie, Guliang Wang, Abbey C. Thompson, et al
 
▲ 链接:
 
http://science.sciencemag.org/content/363/6422/81
 
 
 
▲ 摘要:
 
进化产生了异常多样的生命形式,但很多特征重复进化,而其中的机制仍未被充分理解。
 
 
 
重复进化的一个经典例子是棘鱼骨盆后鳍的丧失。重复的骨盆丧失映射到Pitx1基因这个骨盆增强子的反复删除。
 
 
 
这里,我们确认了导致这些重复删除的分子特征。Pitx1增强子序列形成体外替代性DNA结构,并且增加了体外的双链断裂和删除。增强子突变性取决于DNA复制方向,并且由TG-二核苷酸引发。
 
 
 
模型显示,增加的突变率能影响同棘鱼和人类相关的人口统计学条件下的进化。因此,DNA脆弱性或有助于解释为何相同位点通常在平行适应性进化中被重复利用。
 
 
 
▲ 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
 
丘视觉皮层:古老中脑视觉结构的新皮层空间
 
▲ 作者:Riccardo Beltramo, Massimo Scanziani
 
▲ 链接:
 
http://science.sciencemag.org/content/363/6422/64
 
 
 
▲ 摘要:
 
大脑皮层中的视觉响应被认为依赖于向初级视皮层(V1)的膝状体输入。
 
 
 
的确,V1损伤实质性地降低了通过皮层的视觉响应。视觉信息还通过上丘(SC)进入皮层,但这一输入对于皮层中视觉响应的功能还不太清楚。
 
 
 
SC损伤对大脑皮层视觉响应的影响小于V1损伤,同时似乎没有视觉皮质区域完全依赖于SC输入。
 
 
 
我们证实,小鼠大脑侧视觉皮质区的视觉响应不依赖于V1,并且一旦SC静默,便被废除。这一区域在识别移动物体方面的表现超过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
 
尼日利亚2018年拉沙热疫情爆发中心的宏基因组测序
 
▲ 作者:L. E. Kafetzopoulou, S. T. Pullan, P. Lemey, et al
 
▲ 链接:
 
http://science.sciencemag.org/content/363/6422/74
 
 
 
▲ 摘要:
 
2018年尼日利亚拉沙热发病季经历了有史以来最大规模的病例数攀升,从而引发了关于一种传染率升高的病毒株现身的担忧。
 
 
 
为了解病例数剧增背后的分子流行病学,我们首次在疫情爆发中心开展了直接来自患者样本的宏基因组纳米孔测序。这种方法受到目标病原体高度可变的基因组影响。
 
 
 
基因组数据和系统发育重建结果被立即传送给尼日利亚当局和世界卫生组织,以便为公共卫生应急反应提供信息。
 
 
 
▲ 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.
 
 
 
(宗华)
 
 
 
 
 
 
 
 
 打印  发E-mail给: 
    
 
以下评论只代表网友个人观点,不代表科学网观点。
 
相关新闻 相关论文

图片新闻
“零饥饿”目标面临“隐性”挑战 治病救人的大科学装置,中国有了
全球首架大集成航空物探遥感调查机亮相 机构改革后,如何保护“保护地”
>>更多
 
一周新闻排行 一周新闻评论排行
 
编辑部推荐博文