《科學》（20200904出版）一周論文導讀

編譯 | 未玖

Science, 04 SEPTEMBER 2020, VOL 369, ISSUE 6508

《科學》2020年9月4日，第369卷，6508期

物理學Physics

Proton-electron mass ratio from laser spectroscopy of HD+ at the part-per-trillion level

質子-電子質量比HD +雷射光譜實現萬億分之一精度

▲ 作者：Sayan Patra, M. Germann, J.-Ph. Karr, M. Haidar, L. Hilico, V. I. Korobov, et al.

▲ 連結：

https://science.sciencemag.org/content/369/6508/1238

▲ 摘要

最近對潘寧阱中輕原子核的質量測量表明，密切相關的物理常數（例如質子-電子和氘核-質子質量比）可能存在不一致。這些量還會影響氘化分子氫離子（HD +）電子基態的預測振動光譜。

研究組使用無都卜勒雙光子雷射光譜儀測量了該光譜的v = 0→9泛音躍遷（v，振動量子數）的頻率，不確定度為萬億分之2.9。

通過利用高精度的從頭計算，研究組將測量轉換為嚴格約束質子-電子和氘核-質子質量比，與最近潘寧阱的測量值相符。這使得質子-電子質量比的精確度達到萬億分之21。

▲ Abstract

Recent mass measurements of light atomic nuclei in Penning traps have indicated possible inconsistencies in closely related physical constants such as the proton-electron and deuteron-proton mass ratios. These quantities also influence the predicted vibrational spectrum of the deuterated molecular hydrogen ion (HD +) in its electronic ground state. We used Doppler-free two-photon laser spectroscopy to measure the frequency of the v = 0→9 overtone transition (v, vibrational quantum number) of this spectrum with an uncertainty of 2.9 parts per trillion. By leveraging high-precision ab initio calculations, we converted our measurement to tight constraints on the proton-electron and deuteron-proton mass ratios, consistent with the most recent Penning trap determinations of these quantities. This results in a precision of 21 parts per trillion for the value of the proton-electron mass ratio.

天文學Astronomy

A triple-star system with a misaligned and warped circumstellar disk shaped by disk tearing

錯位扭曲拱星盤撕裂的三星系統

▲ 作者：Stefan Kraus, Alexander Kreplin, Alison K. Young, Matthew R. Bate, John D. Monnier, Tim J. Harries, et al.

▲ 連結：

https://science.sciencemag.org/content/369/6508/1233

▲ 摘要

年輕的恆星被一個由氣體和塵埃組成的拱星盤圍繞著，星盤內部可形成行星。多恆星系統中的引力會撕碎拱星盤。理論模型預測，如果拱星盤與恆星的軌道平面不一致，則盤將扭曲並破裂成進動環，這種現象稱為拱星盤撕裂。

研究組展示了三星系統GW Orionis的觀測結果，發現了拱星盤撕裂的證據。研究組的圖像顯示了一個偏離軌道平面和外星盤的偏心環，該環在拱星盤強烈扭曲的中間區域投下陰影。

若行星可在扭曲的拱星盤中形成，則拱星盤撕裂提供了一種在傾斜軌道上形成大間距行星的機制。

▲ Abstract

Young stars are surrounded by a circumstellar disk of gas and dust, within which planet formation can occur. Gravitational forces in multiple star systems can disrupt the disk. Theoretical models predict that if the disk is misaligned with the orbital plane of the stars, the disk should warp and break into precessing rings, a phenomenon known as disk tearing. We present observations of the triple-star system GW Orionis, finding evidence for disk tearing. Our images show an eccentric ring that is misaligned with the orbital planes and the outer disk. The ring casts shadows on a strongly warped intermediate region of the disk. If planets can form within the warped disk, disk tearing could provide a mechanism for forming wide-separation planets on oblique orbits.

生態學Ecology

Plants sustain the terrestrial silicon cycle during ecosystem retrogression

在生態系統退化過程中，植物維持著陸地矽循環

▲ 作者：F. de Tombeur, B. L. Turner, E. Laliberté, H. Lambers, G. Mahy, M.-P. Faucon, et al.

▲ 連結：

https://science.sciencemag.org/content/369/6508/1245

▲ 摘要

生物地球化學矽循環影響全球初級生產力和碳循環，但人們對陸地生態系統長期發展過程中矽資源和矽循環的變化仍知之甚少。

研究組揭示了在長期的生態系統發展過程中，沿著澳大利亞西部200萬年的土壤時間序列，陸地矽循環從土壤控制轉變為生物控制。

矽的可用性是由新生土壤中的成土矽，以及當成土池枯竭時舊土壤中植物來源矽的循環利用來決定的。不同於主要營養成分濃度在強風化土壤中顯著下降，葉面矽濃度隨著土壤年齡的增長而持續增加。

研究結果表明，在生態系統退化過程中，植物對矽的保留維持了矽在陸地上的循環。這表明在營養不良環境中，植物對保留矽元素有重要益處。

▲ Abstract

The biogeochemical silicon cycle influences global primary productivity and carbon cycling, yet changes in silicon sources and cycling during long-term development of terrestrial ecosystems remain poorly understood. Here, we show that terrestrial silicon cycling shifts from pedological to biological control during long-term ecosystem development along 2-million-year soil chronosequences in Western Australia. Silicon availability is determined by pedogenic silicon in young soils and recycling of plant-derived silicon in old soils as pedogenic pools become depleted. Unlike concentrations of major nutrients, which decline markedly in strongly weathered soils, foliar silicon concentrations increase continuously as soils age. Our findings show that the retention of silicon by plants during ecosystem retrogression sustains its terrestrial cycling, suggesting important plant benefits associated with this element in nutrient-poor environments.

Predicting temperature mortality and selection in natural Drosophila populations

氣溫對自然界果蠅種群死亡率和選擇的影響預測

▲ 作者：Enrico L. Rezende, Francisco Bozinovic, András Szilágyi, Mauro Santos

▲ 連結：

https://science.sciencemag.org/content/369/6508/1242

▲ 摘要

在不久的將來，平均氣溫和極端氣溫將上升，但這種變化將如何影響自然種群的死亡率仍不清楚。

研究組使用動態模型，根據實驗室的耐熱測量結果預測了變溫下的死亡率。在不同升溫條件下，11種果蠅的理論致死溫度與經驗結果幾乎沒有區別。

對於野外果蠅而言，根據環境溫度記錄預測的每日死亡率會在數周甚至數月後累積，這與自然界中觀察到的季節性波動和種群減少相一致。

研究組的模型量化了自然界中由溫度引起的死亡率，這對於研究全球變暖對自然種群的影響至關重要，分析強調，臨界溫度是不可靠的死亡率預測因子。

▲ Abstract

Average and extreme temperatures will increase in the near future, but how such shifts will affect mortality in natural populations is still unclear. We used a dynamic model to predict mortality under variable temperatures on the basis of heat tolerance laboratory measurements. Theoretical lethal temperatures for 11 Drosophila species under different warming conditions were virtually indistinguishable from empirical results. For Drosophila in the field, daily mortality predicted from ambient temperature records accumulate over weeks or months, consistent with observed seasonal fluctuations and population collapse in nature. Our model quantifies temperature-induced mortality in nature, which is crucial to study the effects of global warming on natural populations, and analyses highlight that critical temperatures are unreliable predictors of mortality.

醫學Medicine

Systems biological assessment of immunity to mild versus severe COVID-19 infection in humans

人類輕度與重度COVID-19感染的免疫系統生物學評估

▲ 作者：Prabhu S. Arunachalam, Florian Wimmers, Chris Ka Pun Mok, Ranawaka A. P. M. Perera, Madeleine Scott, Thomas Hagan, et al.

▲ 連結：

https://science.sciencemag.org/content/369/6508/1210

▲ 摘要

COVID-19是一場全球性危機，但人們對SARS-CoV-2的免疫力仍存在重大認知空白。研究組分析了來自中國香港和美國亞特蘭大的76名COVID-19患者和69位健康個體的免疫應答。

在COVID-19患者的外周血單核細胞（PBMCs）中，研究組觀察到髓系細胞表達的人類白細胞抗原類DR（HLA-DR）和促炎細胞因子減少，漿細胞樣樹突狀細胞表達的哺乳動物雷帕黴素（mTOR）信號靶點和幹擾素-a（IFN-a）生成受損。

相比之下，研究組檢測到血漿中炎症介質（包括EN-RAGE、TNFSF14和抑瘤素M）的水平升高，這與疾病嚴重程度和血漿中細菌產物的增加有關。單細胞轉錄組學顯示I型IFNs缺乏，嚴重COVID-19患者的髓系細胞HLA-DR降低，IFN刺激基因短暫表達。這與大量PBMC轉錄和感染期間血漿中短暫的低IFN-a水平一致。

研究結果揭示了COVID-19的機制和潛在的治療靶點。

▲ Abstract

Coronavirus disease 2019 (COVID-19) represents a global crisis, yet major knowledge gaps remain about human immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We analyzed immune responses in 76 COVID-19 patients and 69 healthy individuals from Hong Kong and Atlanta, Georgia, United States. In the peripheral blood mononuclear cells (PBMCs) of COVID-19 patients, we observed reduced expression of human leukocyte antigen class DR (HLA-DR) and proinflammatory cytokines by myeloid cells as well as impaired mammalian target of rapamycin (mTOR) signaling and interferon-α (IFN-α) production by plasmacytoid dendritic cells. By contrast, we detected enhanced plasma levels of inflammatory mediators—including EN-RAGE, TNFSF14, and oncostatin M—which correlated with disease severity and increased bacterial products in plasma. Single-cell transcriptomics revealed a lack of type I IFNs, reduced HLA-DR in the myeloid cells of patients with severe COVID-19, and transient expression of IFN-stimulated genes. This was consistent with bulk PBMC transcriptomics and transient, low IFN-α levels in plasma during infection. These results reveal mechanisms and potential therapeutic targets for COVID-19.

Deep immune profiling of COVID-19 patients reveals distinct immunotypes with therapeutic implications

COVID-19患者的深度免疫分析揭示了三種不同的免疫類型

▲ 作者：Divij Mathew, Josephine R. Giles, Amy E. Baxter, Derek A. Oldridge, Allison R. Greenplate, Jennifer E. Wu, et al.

▲ 連結：

https://science.sciencemag.org/content/369/6508/eabc8511

▲ 摘要

目前COVID-19正在全球大流行，但人們對該病毒的免疫反應知之甚少。研究組採用高維細胞計數法對125例COVID-19患者進行分析，並與康復期和健康人群進行比較。

通過綜合分析200例免疫和50例臨床特徵，研究組發現部分患者T細胞和B細胞亞群激活。其中一個亞組的患者具有急性病毒感染的T細胞活化特徵，循環B細胞的血漿抗體反應超過30% 。然而，另一個亞組的患者淋巴細胞活化與未感染個體相當。

研究組確定了穩定與動態的免疫特徵，並與病情變化的軌跡相關聯。該分析確定了三種與不良臨床軌跡和改善健康相關的免疫類型。這些免疫類型可能有助於COVID-19治療藥物和疫苗的設計。

▲ Abstract

Coronavirus disease 2019 (COVID-19) is currently a global pandemic, but human immune responses to the virus remain poorly understood. We used high-dimensional cytometry to analyze 125 COVID-19 patients and compare them with recovered and healthy individuals. Integrated analysis of ~200 immune and ~50 clinical features revealed activation of T cell and B cell subsets in a proportion of patients. A subgroup of patients had T cell activation characteristic of acute viral infection and plasmablast responses reaching >30% of circulating B cells. However, another subgroup had lymphocyte activation comparable with that in uninfected individuals. Stable versus dynamic immunological signatures were identified and linked to trajectories of disease severity change. Our analyses identified three immunotypes associated with poor clinical trajectories versus improving health. These immunotypes may have implications for the design of therapeutics and vaccines for COVID-19.