翻译 | 唐一尘
Nature, 31 January 2019, Volume 565 Issue 7741
《自然》2019年1月31日第7741期565卷
古人类Paleoanthropology
Timing of archaic hominin occupation of Denisova Cave in southern Siberia
古人类占领南西伯利亚丹尼索瓦洞穴的时间
▲ 作者：ZenobiaJacobs、Bo Li、MichaelV. Shunkov、KieranO’Gorman、AnatolyP. Derevianko、RichardG. Roberts，etal
▲ 链接：
https://www.nature.com/articles/s41586-018-0843-2
▲ 摘要：
丹尼索瓦人属于古人类的一种，其唯一已知的化石来源是在西伯利亚丹尼索瓦洞发现的一些骨骼和牙齿碎片。
但限于丹尼索瓦洞的大小和复杂性，想要可靠地破解古人类占据丹尼索瓦洞的完整历史具有一定难度。
本研究对丹尼索瓦洞的沉积物展开了光释光测年研究，通过估算特定的矿物颗粒（如石英）从末次曝露在阳光下至今所经历的时间进行年代测定。在此基础上，研究人员为洞内化石和人工制品的沉积物建立了年表，时间跨度约为30万～2万年前。
根据作者的保守估计，丹尼索瓦人大约在28.7万～5.5万年前占据了洞穴，而尼安德特人也在约19.3万～9.7万年前出现在洞穴中。
▲ Abstract
The Altai region of Siberia was inhabited for parts of the Pleistocene by at least two groups of archaic hominins—Denisovans and Neanderthals. Denisova Cave, uniquely, contains stratified deposits that preserve skeletal and genetic evidence of both hominins, artefacts made from stone and other materials, and a range of animal and plant remains. The previous site chronology is based largely on radio carbonages for fragments of bone and charcoal that are up to 50,000 years old; older ages of equivocal reliability have been estimated from thermoluminescence and palaeomagnetic analyses of sediments, and genetic analyses of hominin DNA. Here we describe the stratigraphic sequences in Denisova Cave, establish achronology for the Pleistocene deposits and associated remains from opticaldating of the cave sediments, and reconstruct the environmental context of hominin occupation of the site from around 300,000 to 20,000 years ago.
Age estimates for hominin fossils and the onset of the Upper Palaeolithic at Denisova Cave
古人类化石的年代估计和旧石器时代丹尼索瓦洞穴“生活”的开始
▲ 作者：KaterinaDouka、VivianeSlon、ZenobiaJacobs、MichaelV. Shunkov、AnatolyP. Derevianko、SamanthaBrown、JanetKelso、TomHigham，etal
▲ 链接：
https://www.nature.com/articles/s41586-018-0870-z
▲ 摘要：
位于西伯利亚阿尔泰（俄罗斯）的丹尼索瓦洞穴是理解更新世中晚期欧亚大陆古人类群体之间复杂关系的关键地点。
从该遗址发现的人类遗骸中提取的DNA序列揭示了一个迄今未知的古人类群体——丹尼索瓦人的存在，而化石证据也显示尼安德特人和丹尼索瓦人曾出现混合。
本研究对该遗址进行了50次放射性碳测年的最新结果，并描述了3个全新丹尼索瓦人化石碎片。
通过对所有已知丹尼索瓦人化石进行分析，研究人员认为最古老的化石显示丹尼索瓦人可能早在19.5万年前就出现在该遗址，而最新的化石则可追溯至7.6万～5.2万年前。对骨尖状器和牙齿吊坠的放射性碳测年表明，这些人工制品的制作时间为距今4.9万～4.3万年，这使其成为欧亚大陆北部出土的最古老人工制品，并可能由丹尼索瓦人制作。
▲ Abstract
Denisova Cave in the Siberian Altai (Russia) is a key site for understanding the complex relationships between hominin groups that inhabited Eurasia in the Middle and Late Pleistocene epoch. DNA sequenced from human remains found at this site has revealed the presence of a hitherto unknown hominin group, the Denisovans, and high-coverage genomes from both Neanderthal and Denisovan fossils provide evidence for admixture between these two populations. Determining the age of these fossils is important if we are to understand the nature of hominin interaction, and aspects of their cultural and subsistence adaptations. Here we present 50 radiocarbon determinations from the late Middle and Upper Palaeolithic layers of the site. We also report three direct dates for hominin fragments and obtain a mitochondrial DNA sequence for one of them. We apply a Bayesian age modelling approach that combines chronometric (radiocarbon, uranium series and optical ages), stratigraphic and genetic data to calculate probabilistically the age of the human fossils at the site. Our modelled estimate for the age of the oldest Denisovan fossil suggests that this group was present at the site as early as 195,000 years ago (at 95.4% probability). All Neanderthal fossils—as well as Denisova 11, the daughter of a Neanderthal and a Denisovan—date to between 80,000 and 140,000 yearsago. The youngest Denisovan dates to 52,000–76,000 years ago. Direct radiocarbon dating of Upper Palaeolithic tooth pendants and bone points yielded the earliest evidence for the production of these artefacts in northern Eurasia, between 43,000 and 49,000 calibrated years before present (taken as AD 1950). On the basis of current archaeological evidence, it may be assumed that these artefacts are associated with the Denisovan population. It is not currently possible to determine whether anatomically modern humans were involved in their production, as modern-human fossil and genetic evidence of such antiquity has not yet been identified in the Altai region.
物理Physics
Tripled yield indirect-drive laser fusion through statistical modelling
统计模型助力直接驱动激光核聚变产率提高两倍
▲ 作者：V.Gopalaswamy、R.Betti、J. A.Frenje，etal
▲ 链接：
https://www.nature.com/articles/s41586-019-0877-0
▲ 摘要：
将激光聚焦在一个非常小的目标上，可以为实验室规模的氢同位素核聚变创造条件。缺乏精确的预测模型是实现热核点火的主要障碍，而精确的预测模型对高性能激光聚变实验设计至关重要。
本研究报告了一种统计方法，用于设计和定量预测固体氘氚靶内爆结果，结果在30千焦欧米茄激光系统中产生3倍的融合产量是迄今为止直接驱动激光融合的最高值。当放大到国家点火装置的激光能量时，预计将产生约500千兆焦耳的聚变能量输出——比目前实现的聚变能量高出数倍。
该方法可以指导人们对热核点火条件参数空间的探索，提高对激光聚变物理的认识。
▲ Abstract
Focusing laser light onto a very small target can produce the conditions for laboratory-scale nuclear fusion of hydrogen isotopes. The lack of accurate predictive models, which are essential for the design of high-performance laser-fusion experiments, is a major obstacle to achieving thermonuclear ignition. Here we report a statistical approach that was used to design and quantitatively predict the results of implosions of solid deuterium–tritium targets carried out with the 30-kilojoule OMEGA laser system, leading to tripling of the fusion yield to its highest value so far for direct-drive laser fusion. When scaled tothe laser energies of the National Ignition Facility (1.9 megajoules), these targets are predicted to produce a fusion energy output of about 500 kilojoules—several times larger than the fusion yields currently achieved at that facility. This approach could guide the exploration of the vast parameter space of thermonuclear ignition conditions and enhance our understanding of laser-fusion physics.
化学Chemistry
Secondary organic aerosol reduced by mixture of atmospheric vapours
大气蒸汽混合物减少次生有机气溶胶
▲ 作者：GordonMcFiggans、ThomasF. Mentel、AstridKiendler-Scharr，etal
▲ 链接：
https://www.nature.com/articles/s41586-018-0871-y
▲ 摘要：
次生有机气溶胶是大气颗粒物的重要组成部分，对大气质量和气候有重要影响。
植物释放的萜类等生物源挥发性有机化合物是重要的次生有机气溶胶前体，而异戊二烯支配着全球生物挥发性有机化合物的排放。
本研究发现异戊二烯、一氧化碳和甲烷都能抑制大气中单萜化合物在混合气体中的瞬时质量和总质量产额。
研究人员发现异戊二烯能“清除”羟基自由基，阻止它们与单萜烯反应，降低了原本会形成次生有机气溶胶的低挥发性产品的产量。因此，产生少量气溶胶的高度反应性化合物（如异戊二烯）不一定是次生有机颗粒质量的净产生者，它们在大气蒸汽混合物中的氧化作用可以抑制次生有机气溶胶的颗粒数和质量。
研究人员认为，大气中次生有机气溶胶的形成机制需要考虑氧化前体分子产物之间的机械相互作用。
▲ Abstract
Secondary organic aerosol contributes to the atmospheric particle burden with implications for air quality and climate. Biogenic volatile organic compounds such as terpenoids emitted from plants are important secondary organic aerosol precursors with isoprene dominating the emissions of biogenic volatile organic compounds globally. However, the particle mass from isoprene oxidation is generally modest compared to that of other terpenoids. Here we show that isoprene, carbon monoxide and methane can each suppress the instantaneous mass and the overall mass yield derived from monoterpenes in mixtures of atmospheric vapours. We find that isoprene ‘scavenges’ hydroxyl radicals, preventing their reaction with monoterpenes, and the resulting isoprene peroxy radicals scavenge highly oxygenated monoterpene products. These effects reduce the yield of low-volatility products that would otherwise form secondary organic aerosol. Global model calculations indicatethat oxidant and product scavenging can operate effectively in the realatmosphere. Thus highly reactive compounds (such as isoprene) that produce a modest amount of aerosol are not necessarily net producers of secondary organic particle mass and their oxidation in mixtures of atmospheric vapours cansuppress both particle number and mass of secondary organic aerosol. We suggest that formation mechanisms of secondary organic aerosol in the atmosphere need to be considered more realistically, accounting for mechanistic interactions between the products of oxidizing precursor molecules (as is recognized to be necessary when modelling ozone production).
生物Biology
A defined commensal consortium elicits CD8 T cells and anti-cancer immunity
共生体可诱导CD8 T细胞和抗癌免疫
▲ 作者：TakeshiTanoue、SatoruMorita、KenyaHonda，etal
▲ 链接：
https://www.nature.com/articles/s41586-019-0878-z
▲ 摘要：
人们越来越认识到肠道微生物群作为各种疾病的治疗靶点的重要性。然而，只有少数已知的共生体菌株有可能被用来操纵宿主的生理功能。
这里研究人员报道了一种新发现的抗肿瘤免疫机制，这种机制涉及人体肠道菌群诱导产生干扰素γ（IFNγ）的CD8+ T细胞在肠道和肿瘤中积累。
相关细菌菌株混合物利用这种抗肿瘤机制，并协同性地加强对免疫检查点抑制剂和免疫挑战作出的反应。
在模型中，混合物定植小鼠不仅增强了对单核增生李斯特菌感染的抵抗力，而且增强了免疫检查点抑制剂的治疗效果。而且，这项研究首次证实协同增强免疫检查点抑制剂反应的源自人类微生物组的细菌混合物是能够被确定出来的。
▲ Abstract
There is a growing appreciation for the importance of the gut microbiota as a therapeutic targetin various diseases. However, there are only a handful of known commensal strains that can potentially be used to manipulate host physiological functions. Here we isolate a consortium of 11 bacterial strains from healthy human donor faeces that is capable of robustly inducing interferon-γ-producing CD8 T cells in the intestine. These 11 strains act together to mediate the induction without causing inflammation in a manner that is dependent on CD103+dendritic cells and major histocompatibility (MHC) class Ia molecules. Colonization of mice with the 11-strain mixture enhances both host resistance against Listeria monocytogenes infection and the therapeutic efficacy of immune checkpoint inhibitors in syngeneic tumour models. The 11 strains primarily represent rare, low-abundance components of the human microbiome, and thus have great potential as broadly effective biotherapeutics.
Excised linear introns regulate growth in yeast
内含子调节酵母生长
▲ 作者：JeffreyT. Morgan、GeraldR. Fink、DavidP. Bartel，etal
▲ 链接：
https://www.nature.com/articles/s41586-018-0828-1
▲ 摘要：
内含子是真核生物体内普遍存在的非编码RNA，它在新生mRNA中被剪接去除以产生功能性蛋白质，但其生物学功能至今仍未被阐释清楚。
本研究对酿酒酵母的34个内含子进行了删除，发现虽然线性RNA在饱和生长条件或其他应激条件下进行积累，但在对数期生长期中迅速降解，从而长期抑制生长信号TORC1。
这些内含子的删除对饱和生长条件下的酵母是不利的，并且在TORC1抑制剂雷帕霉素作用下，酵母生长速率异常升高。回补相应的天然或人工内含子可以有效抑制雷帕霉素导致的异常作用。
此外，内含子的稳定与剪接体的组分相关，较近的套索分支点和3'端剪接位点间距是内含子稳定的必要条件。该研究揭示了内含子在酿酒酵母TOR生长信号传导网络内的作用及剪接体内含子的生物学功能。
▲ Abstract
Spliceosomal introns are ubiquitous non-coding RNAs that are typically destined for rapid debranching and degradation. Here we describe 34 excised introns in Saccharomyces cerevisiae that—despite being rapidly degraded inlog-phase growth—accumulate as linear RNAs under either saturated-growth conditions or other stresses that cause prolonged inhibition of TORC1, which is a key integrator of growth signalling. Introns that become stabilized remain associated with components of the spliceosome and differ from other spliceosomal introns in having a short distance between their lariat branch point and 3′ splice site, which is necessary and sufficient for their stabilization. Deletion of these unusual introns is disadvantageous in saturated conditions and causes aberrantly high growth rates in yeast that arechronically challenged with the TORC1 inhibitor rapamycin. The reintroduction of native or engineered stable introns suppresses this aberrant rapamycin response. Thus, excised introns function within the TOR growth-signalling network of S. cerevisiae and, more generally, excised spliceosomal introns can have biological functions.
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