《科學》（20181221出版）一周論文導讀

Science, 21 DECEMBER 2018, VOL 362, ISSUE 6421

《科學》2018年12月21日第6421期362卷

植物學Botany

A hidden cradle of plant evolution in Permian tropical lowlands

二疊紀赤道低地植物進化的隱藏搖籃

作者：Patrick Blomenkemper, Hans Kerp, Abdalla Abu Hamad, et al

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摘要：

今天的緯度方向生物多樣性梯度，深深植根於整個地質時期地球生物區系的進化歷史。

在海相環境中，低緯度地區出現的最早化石揭示了熱帶是很多動物群的搖籃。

不過，陸地化石記錄，尤其是來自被認為驅動進化創新的較乾旱環境的化石很稀少。

這裡，我們展示了形形色色的植物化石集合。它們來自今天的約旦二疊紀赤道低地，蘊藏著在中生代均佔據主導地位的3大種子植物譜系的早期發育記錄，包括任何現存針葉樹家族的最古老代表。

這些發現展示了在易受干擾地區通常不被觀察到的現代植物群的早期進化起源。

Abstract

The latitudinal biodiversity gradient today has deep roots in the evolutionary history of Earth』s biota over geologic time. In the marine realm, earliest fossil occurrences at low latitudes reveal a tropical cradle for many animal groups. However, the terrestrial fossil record—especially from drier environments that are thought to drive evolutionary innovation—is sparse. We present mixed plant-fossil assemblages from Permian equatorial lowlands in present-day Jordan that harbor precocious records of three major seed-plant lineages that all became dominant during the Mesozoic, including the oldest representative of any living conifer family. These finds offer a glimpse of the early evolutionary origins of modern plant groups in disturbance-prone tropical habitats that are usually hidden from observation.

Root branching toward water involves posttranslational modification of transcription factor ARF7

根系向水分支涉及轉錄因子ARF7翻譯後修飾

作者：Beatriz Orosa-Puente, Nicola Leftley, Daniel von Wangenheim, et al

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摘要：

植物通過改變根系構型適應不同種類的土壤條件。比如，根在同水接觸時通過利用水力模式響應產生分支。

我們報告稱，水力模式依賴於生長素響應因子ARF7。該轉錄因子誘導其靶向基因LBD16在側根生成細胞中的不對稱表達。

這種有差別的表達模式受到擁有小分子泛素樣修飾體（SUMO）蛋白質的ARF7翻譯後修飾的調控。SUMO化負向調節ARF7的DNA結合活性。

同時，「招募」Aux/IAA（吲哚-3-醋酸）阻遏蛋白IAA3需要ARF7的SUMO化。阻止ARF7的SUMO化擾亂了IAA3的招募和水力模式形成。

Abstract

Plants adapt to heterogeneous soil conditions by altering their root architecture. For example, roots branch when in contact with water by using the hydropatterning response. We report that hydropatterning is dependent on auxin response factor ARF7. This transcription factor induces asymmetric expression of its target gene LBD16 in lateral root founder cells. This differential expression pattern is regulated by posttranslational modification of ARF7 with the small ubiquitin-like modifier (SUMO) protein. SUMOylation negatively regulates ARF7 DNA binding activity. ARF7 SUMOylation is required to recruit the Aux/IAA (indole-3-acetic acid) repressor protein IAA3. Blocking ARF7 SUMOylation disrupts IAA3 recruitment and hydropatterning.

物理學 Physics

Single-component quasicrystalline nanocrystal superlattices through flexible polygon tiling rule

遵循柔性多邊形平鋪規則的單組分准晶體納米晶超晶格

作者：Yasutaka Nagaoka, Hua Zhu, Dennis Eggert, Ou Chen

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摘要：

產生自單組分膠體構建塊的准晶體超晶格（QC-SLs）已被計算機模擬預測出來，但在試驗中再現一直面臨挑戰。

我們發現，10倍QC-SLs能從擁有各向異性分布的截尾四面體量子點自我組織形成。

透射電鏡和斷層掃描測量使QC-SL實現了從納米尺度填充到原子尺度定向排列的結構重建。

獨特的准晶體順序帶來了「貼瓷磚」概念，即柔性多邊形平鋪規則。這再現了試驗觀測。

Abstract

Quasicrystalline superlattices (QC-SLs) generated from single-component colloidal building blocks have been predicted by computer simulations but are challenging to reproduce experimentally. We discovered that 10-fold QC-SLs could self-organize from truncated tetrahedral quantum dots with anisotropic patchiness. Transmission electron microscopy and tomography measurements allow structural reconstruction of the QC-SL from the nanoscale packing to the atomic-scale orientation alignments. The unique QC order leads to a tiling concept, the 「flexible polygon tiling rule,」 that replicates the experimental observations.

Magnetic hysteresis up to 80 kelvin in a dysprosium metallocene single-molecule magnet

鏑茂金屬單分子磁體中磁滯現象達到80開爾文

作者：Fu-Sheng Guo, Benjamin M. Day, Yan-Cong Chen, et al

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摘要：

僅含有一個金屬中心的單分子磁體（SMMs）可能代表了基於分子的磁性信息儲存材料的尺寸下限。

其現有短板是所有SMMs需要液態氦冷卻，才能表現出磁記憶效應。

我們現在報告了一種化學策略來獲取鏑茂金屬陽離子。其在液氮溫度以上展現出磁滯現象。

U_eff = 1541波數的磁化反轉的有效能壘也得到測量。

針對這種陽離子的T_B =80開爾文的磁屏蔽溫度克服了研製在實際溫度下發揮作用的納米磁體設備的重要障礙。

Abstract

Single-molecule magnets (SMMs) containingonly one metal center may represent the lower size limit for molecule-basedmagnetic information storage materials. Their current drawback is that all SMMsrequire liquid-helium cooling to show magnetic memory effects. We now report achemical strategy to access the dysprosium metallocene cation, which displaysmagnetic hysteresis above liquid-nitrogen temperatures. An effective energybarrier to reversal of the magnetization of U_eff = 1541 wave number is alsomeasured. The magnetic blocking temperature of T_B = 80 kelvin for this cationovercomes an essential barrier toward the development of nanomagnet devicesthat function at practical temperatures.

天體物理學 Astrophysics

Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b

對質量和木星相當的系外行星WASP-69b擴展氦大氣層的地基觀測

作者：Lisa Nortmann, Enric Pallé, Michael Salz, et al

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摘要：

由於強烈的恆星輻射，巨大的熱氣體系外行星會失去部分大氣，而這會影響它們的物理和化學演化。

對來自系外行星的大氣逃逸進行研究，大部分依靠基於太空的遠紫外線區氫賴曼—阿爾法線觀測。這受到星際吸收的強烈影響。

利用地基高解析度光譜，我們探測到質量和木星相當的系外行星WASP-69b凌日期間，在信噪比為18的情況下1083納米氦三聯體的過度吸收。

我們測量了每秒鐘若干公里的線藍移和凌日後吸收，並將其解讀為以類似於彗星的形式拖在該行星後面的部分大氣的逃逸。

Abstract

Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, and these losses can affect their physical and chemical evolution. Studies of atmospheric escape from exoplanets have mostly relied on space-based observations of the hydrogen Lyman-α line in the far ultraviolet region, which is strongly affected by interstellar absorption. Using ground-based high-resolution spectroscopy, we detected excess absorption in the helium triplet at 1083 nanometers during the transit of the Saturn-mass exoplanet WASP-69b, at a signal-to-noise ratio of 18. We measured line blueshifts of several kilometers per second and posttransit absorption, which we interpret as the escape of part of the atmosphere trailing behind the planet in comet-like form.

Spectrally resolved helium absorption from the extended atmosphere of a warm Neptune-mass exoplanet

來自質量和海王星相當的溫暖地外行星擴展大氣層的光譜分辨氦吸收

作者：R. Allart1, V. Bourrier, C. Lovis, D. Ehrenreich, et al

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摘要：

恆星加熱導致附近地外行星大氣層擴展和逃逸。

這些擴展的大氣層很難被觀測到，因為它們的主要光譜特徵——紫外波段的中性氫被星際介質大量吸收。

我們利用地基高解析度觀測結果，探測了正在凌日的質量和海王星相當的溫暖地外行星HAT-P-11b中性氦的近紅外三聯體。

氦特徵在兩次獨立的凌日過程中是可重複的，平均吸收深度為1.08 ± 0.05%。

利用對該行星上層大氣的三維模擬對吸收光譜進行的解讀表明，它擴展到5個行星半徑之外，大尺度高度和氦質量損失率為每秒?3×10⁵克。

Abstract

Stellar heating causes atmospheres of close-in exoplanets to expand and escape. These extended atmospheres are difficult to observe because their main spectral signature—neutral hydrogen at ultraviolet wavelengths—is strongly absorbed by interstellar medium. We report the detection of the near-infrared triplet of neutral helium in the transiting warm Neptune-mass exoplanet HAT-P-11b by using ground-based, high-resolution observations. The helium feature is repeatable over two independent transits, with an average absorption depth of 1.08 ± 0.05%. Interpreting absorption spectra with three-dimensional simulations of the planet』s upper atmosphere suggests that it extends beyond 5 planetary radii, with a large-scale height and a helium mass loss rate of ?3 × 10⁵grams per second.

生態學Ecology

Elevated trawling inside protected areas undermines conservation outcomes in a global fishing hot spot

保護區內拖網捕魚增多逐漸破壞生態保護結果

作者：Manuel Dureuil, Kristina Boerder, Kirsti A. Burnett, et al

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摘要：

海洋保護區（MPAs）正日益被用作保護生物多樣性的重要工具。這在歐洲等得到極度開發利用的漁業熱點地區尤其重要。

在歐洲，MPAs目前覆蓋29%的領海，且對漁獲壓力和保護結果的影響未知。我們研究了歐盟指定的727個MPAs及其附近的工業拖網捕魚和敏感指示物種的情況。

研究發現，59%的MPAs出現了商業化的拖網捕魚，同時平均拖網捕撈強度至少比非保護區高1.4倍。鯊魚、鰩魚等敏感物種的丰度在拖網捕魚情況嚴重地區下降了69%。

Abstract

Marine protected areas (MPAs) are increasingly used as a primary tool to conserve biodiversity. This is particularly relevant in heavily exploited fisheries hot spots such as Europe, where MPAs now cover 29% of territorial waters, with unknown effects on fishing pressure and conservation outcomes. We investigated industrial trawl fishing and sensitive indicator species in and around 727 MPAs designated by the European Union. We found that 59% of MPAs are commercially trawled, and average trawling intensity across MPAs is at least 1.4-fold higher as compared with nonprotected areas. Abundance of sensitive species (sharks, rays, and skates) decreased by 69% in heavily trawled areas.

生物學Biology

NK cell–mediated cytotoxicity contributes to tumor control by a cytostatic drug combination

自然殺傷細胞介導細胞毒性促成抑制細胞生長組合藥物的腫瘤控制

作者：Marcus Ruscetti, Josef Leibold, Matthew J. Bott1, et al

鏈接：

摘要：

分子靶向治療旨在阻礙腫瘤生長所需的細胞自主程序。

我們證實，促分裂原活化蛋白激酶（MAPK）和周期蛋白依賴性激酶4/6抑製劑共同作用，抑制KRAS突變型肺癌細胞擴散，並且同時啟動導致腫瘤細胞死亡的自然殺傷（NK）細胞監視程序。

這種藥物組合促進了成視網膜細胞瘤（RB）蛋白質介導細胞衰老和免疫調節衰老相關分泌表型的激活（SASP）。

SASP組件腫瘤壞死因子-α和細胞間黏附分子-1是藥物治療腫瘤細胞的NK細胞監視所必需的。

這導致了腫瘤退化以及KRAS突變型肺癌小鼠模型的延長生存。

Abstract

Molecularly targeted therapies aim to obstruct cell autonomous programs required for tumor growth. We show that mitogen-activated protein kinase (MAPK) and cyclin-dependent kinase 4/6 inhibitors act in combination to suppress the proliferation of KRAS-mutant lung cancer cells while simultaneously provoking a natural killer (NK) cell surveillance program leading to tumor cell death. The drug combination, but neither agent alone, promotes retinoblastoma (RB) protein-mediated cellular senescence and activation of the immunomodulatory senescence-associated secretory phenotype (SASP). SASP components tumor necrosis factor–α and intercellular adhesion molecule–1 are required for NK cell surveillance of drug-treated tumor cells, which contributes to tumor regressions and prolonged survival in a KRAS-mutant lung cancer mouse model.

（宗華）

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