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《自然》(20181011出版)一周論文導讀

10月
13
2018

2018年10月13日15時 今日科學 科學網

科學網

Volume 562 Issue 7726, 11 October 2018

2018年10月11日,第562卷第7726期

生物科學Bio-Science

Common genetic variants contribute to risk of rare severe neurodevelopmental disorders

常見遺傳變異增加罕見嚴重神經發育障礙風險

▲ 作者:Mari E. K. Niemi, Hilary C. Martin, Daniel L. Rice, Giuseppe Gallone, et al.

▲ 導讀:

具有相同遺傳缺陷的患者可能有不同的臨床表現,一些攜帶已知致病變異基因的患者可能看起來似乎並未受到影響。

為了理解這些差異的原因,作者研究了6987名兒童構成的同生群,他們被臨床遺傳學家診斷為患有嚴重的神經發育障礙,同時經常伴有其他器官系統異常。

雖然這些神經發育障礙的遺傳原因預計幾乎完全是單基因的,但研究者發現7.7%的風險變異可歸因於繼承性的共同遺傳變異。

研究者發現,個體之間是否有一種已知蛋白編碼診斷變異,其共有變異風險並沒有顯著差異,這表明共有變異風險會影響有和沒有單基因診斷的患者。

此外,此前發表的自閉症、身高、出生體重和顱內容積的共同變異情況均與此次研究同生群的這些特徵相關,表明單基因障礙患者的表型表達受到與普通人群相同變異的影響。

研究結果表明,常見的遺傳變異既影響總體風險,也影響通常被認為是單基因的神經發育障礙的臨床表現。

▲ Abstract:Patients with the same genetic defect can have different clinical presentations, and some individuals who carry known disease-causing variants can appear unaffected.

Here, to understand what explains these differences, we study a cohort of 6,987 children assessed by clinical geneticists to have severe neurodevelopmental disorders, often in combination with

abnormalities of other organ systems. Although the genetic causes of these neurodevelopmental disorders are expected to be almost entirely monogenic, we show that 7.7% of variance in risk is

attributable to inherited common genetic variation. We found that common-variant risk was not significantly different between individuals with and without a known protein-coding diagnostic variant,

which suggests that common-variant risk affects patients both with and without a monogenic diagnosis. In addition, previously published common-variant scores for autism, height, birth weight and

intracranial volume were all correlated with these traits within our cohort, which suggests that phenotypic expression in individuals with monogenic disorders is affected by the same variants as in

the general population. Our results demonstrate that common genetic variation affects both overall risk and clinical presentation in neurodevelopmental disorders that are typically considered to be

monogenic.

Principles of nucleosome organization revealed by single-cell micrococcal nuclease sequencing

單細胞微球菌核酸酶測序揭示核小體組織原理

▲ 作者:Binbin Lai, Weiwu Gao, Kairong Cui, Wanli Xie, et al.

▲ 導讀:

即使在同源的細胞群中,細胞在響應活躍的信號時也表現出異質性,這可能與染色質可及性的異質性有關。

研究人員報告了一種叫作單細胞微球菌核酸酶測序(scmnas -seq)的技術,可用於同時測量單個細胞中的全基因組核小體定位和染色質可及性。

研究者發現了脫氧核糖核酸酶I(DNase I)超敏位點核小體間隔的雙峰分布,該分布與不可及和可及狀態相對應,並且與核小體變異和細胞間可及性的變異有關。

核小體變異在單個細胞中比跨細胞更少,在同一細胞類型中比跨細胞類型更少。

大量的原始CD4 T細胞和小鼠胚胎幹細胞顯示,在其各自分化譜系中檢測到的新生增強子中,核糖體的占用減少,這表明在未分化的細胞群中,存在著準備分化為特定譜系的細胞。

▲ Abstract:Even in a homogenous population of cells, cells exhibit heterogeneity in expression in response to active signalling that may be related to heterogeneity in chromatin

accessibility. Here we report a technique, termed single-cell micrococcal nuclease sequencing (scMNase-seq), that can be used to simultaneously measure genome-wide nucleosome positioning and

chromatin accessibility in single cells. We found a bimodal distribution of nucleosome spacing at DNase I hypersensitive sites, which corresponds to inaccessible and accessible states and is

associated with nucleosome variation and variation in accessibility across cells. Nucleosome variation is smaller within single cells than across cells, and smaller within the same cell type than

across cell types. A large fraction of naive CD4 T cells and mouse embryonic stem cells shows depleted nucleosome occupancy at the de novo enhancers detected in their respective differentiated

lineages, revealing the existence of cells primed for differentiation to specific lineages in undifferentiated cell populations.

Extended Data Fig. 3: Measuring uniformity in nucleosome spacing in single cells. 測量單個細胞內核小體間距均勻性

Electronic noise due to temperature differences in atomic-scale junctions

由原子尺度結點溫差產生的電子噪聲

▲ 導讀:

自一個世紀前發現電子熱噪聲和散射噪聲以來,這些基本噪聲形式對科學技術的研究和應用產生了巨大的影響。

研究者報告了對一種基本電子噪聲的測量,該噪聲是由納米級導體之間的溫差產生的,研究者稱之為「delta-T 噪聲」。

研究結果表明,delta-T噪聲不同於熱噪聲和電壓激活的散射噪聲。與熱噪聲一樣,delta-T噪聲也有純熱源,但它只有在不平衡的情況下才會產生。

delta-T噪聲和標準散射噪聲具有相同的劃分起源,但卻是被不同的刺激因素激活的。研究者推斷,delta-T噪聲可與熱噪聲結合,用於檢測納米導體之間的溫差,而不需要製造精密的局部探針。

因此,它可以極大地促進納米尺度的熱傳輸研究。

▲ Abstract: Since the discovery a century ago of electronic thermal noise and shot noise, these forms of fundamental noise have had an enormous impact on science and technology

research and applications. Here we report measurements of a fundamental electronic noise that is generated by temperature differences across nanoscale conductors, which we term 『delta-T noise』. Our

findings show that delta-T noise is distinct from thermal noise and voltage-activated shot noise. Like thermal noise, it has a purely thermal origin, but delta-T noise is generated only out of

equilibrium. Delta-T noise and standard shot noise have the same partition origin, but are activated by different stimuli. We infer that delta-T noise in combination with thermal noise can be used to

detect temperature differences across nanoscale conductors without the need to fabricate sophisticated local probes. Thus it can greatly facilitate the study of heat transport at the nanoscale.

Solution-processable 2D semiconductors for high-performance large-area electronics

用於高性能大面積電子產品的可溶液旋塗二維半導體

▲ 作者:Zhaoyang Lin, Yuan Liu, Udayabagya Halim, Mengning Ding, et al.

▲ 導讀:

製備高質量的可溶液旋塗二維半導體納米片仍然是一個挑戰。

研究者報告了一種製備高度均勻的、可溶液旋塗的相純半導體納米片的通用方法,該方法包括將季銨鹽分子電化學插入到二維晶體中,然後進行溫和的聲波降解和剝離過程。

通過對插層化學的精確控制,得到了薄相純半導體2H-MoS2納米片。

然後,這些納米片被進一步加工成高性能薄膜電晶體,在室溫下,其移動速度約為10平方厘米每伏特每秒,開/關比為106,大大超過以往溶液旋塗的MoS2薄膜電晶體。

大型薄膜電晶體陣列的大規模製造使得功能邏輯閘和計算電路的構建成為可能。

▲ Abstract:Preparing high-quality solution-processable 2D semiconductor nanosheets remains a challenge. We report a general approach to preparing highly uniform,

solution-processable, phase-pure semiconducting nanosheets, which involves the electrochemical intercalation of quaternary ammonium molecules into 2D crystals, followed by a mild sonication and

exfoliation process. By precisely controlling the intercalation chemistry, we obtained phase-pure, semiconducting 2H-MoS2 nanosheets with a narrow thickness distribution. These nanosheets were then

further processed into high-performance thin-film transistors, with room-temperature mobilities of about 10 square centimetres per volt per second and on/off ratios of 106 that greatly exceed those

obtained for previous solution-processed MoS2 thin-film transistors. The scalable fabrication of large-area arrays of thin-film transistors enabled the construction of functional logic gates and

computational circuits.

Extended Data Fig. 1: Molecular intercalation and exfoliation of MoS2 2

天體物理學Astrophysics

An evolving jet from a strongly magnetized accreting X-ray pulsar

來自強磁化吸積X射線脈衝星的演變性噴流

▲ 作者:J. van den Eijnden, N. Degenaar, T. D. Russell, R. Wijnands, et al.

▲ 導讀:

相對論性噴流在整個宇宙中都可以觀察到,並在從雙星系統到星系和星系團的物理尺度範圍內強烈地影響著它們周圍的環境。

研究人員報告了由強磁化中子星發射的不斷演化的噴流的觀測結果,該噴流的吸積速率超過了愛丁頓極限給出的理論最高速率。

其射電光度比其他具有類似X射線發光強度的中子星微弱兩個數量級,這意味著中子星的性質在調節射流強度方面具有重要作用。

研究結果還表明,超亮X射線脈衝星的強磁場並不能阻止這些源頭髮射噴流。

▲ Abstract: Relativistic jets are observed throughout the Universe and strongly affect their surrounding environments on a range of physical scales, from Galactic binary systems1

to galaxies and clusters of galaxies. Here we report observations of an evolving jet launched by a strongly magnetized neutron star accreting above the theoretical maximum rate given by the Eddington

limit. The radio luminosity of the jet is two orders of magnitude fainter than those seen in other neutron stars with similar X-ray luminosities9, implying an important role for the properties of the

neutron star in regulating jet power. Our result also shows that the strong magnetic fields of ultra-luminous X-ray pulsars do not prevent such sources from launching jets.

脈衝星在發出強大輻射光束的同時快速旋轉。圖片來源:Dana Berry/NASA

Fig. 1: Marginal posterior distributions for the distance to Sw J0243. 到Sw J0243距離的邊際後驗分布。

Nearly all the sky is covered by Lyman-α emission around high-redshift galaxies

幾乎所有天空覆蓋著高紅移星系周圍的萊曼-α放射

▲ 作者:L. Wisotzki, R. Bacon, J. Brinchmann, S. Cantalupo, P. Richter, et al.

▲ 導讀:

通過萊曼-α放射跟蹤宇宙中的氫是觀測天體物理學的一個長期目標,但這種廣泛延伸的發射的表面亮度卻極低,從而形成了難以逾越的障礙。

近日,來自高紅移星系周圍氫無處不在的萊曼-α放射的發現為觀察周圍的星系環境打開了一個新窗口。這種測量以前僅限於特別有利的天體系統,或是由於該放射很微弱而要使用大量統計進行平均。

此次,研究者報告在3至6等微弱星系紅移周圍觀察到低表面亮度的萊曼-α放射。他們發現,天空投射覆蓋率接近100%。

相應的入射率(由任意視線洞察的萊曼-α放射極的平均數量)遠高於整體,並且類似於高密度吸收體經常在遙遠的類星體光譜中探測到的入射率。

這種相似性表明,這些紅移星系周圍的大多數氫原子已經在發射中被探測到。

▲ Abstract: Tracing cosmic hydrogen through its Lyman-α emission has been a long-standing goal of observational astrophysics, but the extremely low surface brightness of the

spatially extended emission is a formidable obstacle. A new window into circumgalactic environments was recently opened by the discovery of ubiquitous extended Lyman-α emission from hydrogen around

high-redshift galaxies. Such measurements were previously limited to especially favourable systems or to the use of massive statistical averaging because of the faintness of this emission. Here we

report observations of low-surface-brightness Lyman-αemission surrounding faint galaxies at redshifts between 3 and 6. We find that the projected sky coverage approaches 100 per cent. The

corresponding rate of incidence (the mean number of Lyman-α emitters penetrated by any arbitrary line of sight) is well above unity and similar to the incidence rate of high-column-density absorbers

frequently detected in the spectra of distant quasars. This similarity suggests that most circumgalactic atomic hydrogen at these redshifts has now been detected in emission.

Extended Data Fig. 1: Spatial distribution and redshifts of the Lyα emitter sample.

萊曼-α放射體樣本的空間分布和紅移。

氣候Climate

Trade-offs in using European forests to meet climate objectives

對利用歐洲森林實現氣候目標的權衡

▲ 作者:Sebastiaan Luyssaert, Guillaume Marie, Aude Valade, Yi-Ying Chen,et al.

▲ 導讀:

歐洲提出的可持續森林管理的投資組合是否符合巴黎協議尚待確認,也就是說尚不能確定該組合能否降低大氣中CO2的增長速度、減少大氣層頂部輻射的失衡,以及在21世紀結束時,既不會增加近地表氣溫也不會減少降水。

這項研究展示了由管理系統組成的投資組合通過碳封存、木材使用、產品和能源替代等辦法在局部地區讓碳匯最大化,降低了局地大氣CO2的增長率,但並未滿足任何其他標準。

研究結果表明,如果目前的森林覆蓋能夠持續下去,通過森林管理獲得的額外氣候效益將是有限的、局部的,而非全球性的。

基於此,研究者認為歐洲不應該依賴森林管理緩解氣候變化。

▲ Abstract:It remains to be confirmed whether commonly proposed sustainable European forest-management portfolios would comply with the Paris Agreement—that is, whether they can

reduce the growth rate of atmospheric CO2, reduce the radiative imbalance at the top of the atmosphere, and neither increase the near-surface air temperature nor decrease precipitation by the end of

the twenty-first century. Here we show that the portfolio made up of management systems that locally maximize the carbon sink through carbon sequestration, wood use and product and energy

substitution reduces the growth rate of atmospheric CO2, but does not meet any of the other criteria. Our results demonstrate that if present-day forest cover is sustained, the additional climate

benefits achieved through forest management would be modest and local, rather than global. On the basis of these findings, we argue that Europe should not rely on forest management to mitigate

climate change.

Extended Data Table 1 Changes in surface area of European forests by 2100 for six different forest-management portfolios. 到2100年,用於6個不同的森林管理組合的歐洲森林面積的變化。

Effects of climate warming on photosynthesis in boreal tree species depend on soil moisture

氣候變暖對北方樹種光合作用的影響取決於土壤水分

▲ 作者:Peter B. Reich, Kerrie M. Sendall, Artur Stefanski, et al.

▲ 導讀:

氣候變暖會通過熱效應以及改變土壤濕度影響光合作用。這兩種效應對全球森林廣大區域來說都可能很重要。

研究展示了隨著生長季節從雨季過渡到適度乾旱期,氣候變暖對南北方樹種從積極到消極的影響。

在對11種溫帶和北方幼林的進行為期3年的露天增溫實驗中,當氣溫升高3.4℃時,最濕潤土壤中的光飽和凈光合作用和葉片擴散電導平均在1/3的時間裡增加了。

而在乾旱期,所有11種植物的葉片擴散電導以及光飽和凈光合作用均下降了,而且溫度升高的植物中的相關下降幅度比在常溫下的植物大得多。因此,在乾旱土壤中,溫度升高在2/3的時間裡減少了光飽和凈光合作用。

由此可見,低土壤濕度可能會降低,甚至逆轉氣候變暖在濕度適中、季節性寒冷環境下光合作用的潛在益處,而且在生長季節期間的乾旱期和經常發生濕度乾旱期均會如此。

▲ Abstract:Climate warming will influence photosynthesis via thermal effects and by altering soil moisture. Both effects may be important for the vast areas of global forests.

Here we show that the effects of climate warming flip from positive to negative as southern boreal forests transition from rainy to modestly dry periods during the growing season. In a three-year

open-air warming experiment with juveniles of 11 temperate and boreal tree species, an increase of 3.4 °C in temperature increased light-saturated net photosynthesis and leaf diffusive conductance on

average on the one-third of days with the wettest soils. In all 11 species, leaf diffusive conductance and, as a result, light-saturated net photosynthesis decreased during dry spells, and did so

more sharply in warmed plants than in plants at ambient temperatures. Consequently, across the 11 species, warming reduced light-saturated net photosynthesis on the two-thirds of days with driest

soils. Thus, low soil moisture may reduce, or even reverse, the potential benefits of climate warming on photosynthesis in mesic, seasonally cold environments, both during drought and in regularly

occurring, modestly dry periods during the growing season.

Fig. 1 Soil water (VWC) in relation to day of year. 土壤水分(VWC)與時間的關聯。

(晉楠)

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