編譯 | 馮維維
Science , VOLUME 386,ISSUE 6718,11 OCT 2024
【科學】 第386卷，6718期，2024年10月11日
生態 Ecology
Hidden comet tails of marine snow impede ocean-based carbon sequestration
「海洋雪」中的隱藏「彗尾」有礙海洋碳封存
▲ 作者：RAHUL CHAJWA, ELIOTT FLAUM, KAY D. BIDLE, BENJAMIN VAN MOOY, AND MANU PRAKASH
▲ 連結：
https://www.science.org/doi/10.1126/science.adl5767
▲ 摘要：
下沈的海洋微粒有機物質，通常被稱為「海洋雪」，將大量的碳從海洋表面轉移到深處，構成了地球碳迴圈的主要組成部份之一。這些粒子的生物和物理復雜性，及其運動中所涉及的長度和時間尺度的廣泛範圍，使得詳細確定它們的動力學變得極其困難。
Chajwa等人使用顯微成像技術發現，這些顆粒普遍表現出尾巴狀的流動形態，這極大地影響了它們的運動以及它們在深海中封存了多少碳。
▲ Abstract：
Sinking marine particulate organic matter, commonly called 「marine snow,」 moves huge amounts of carbon from the new-surface ocean to depth, constituting one of the major components of Earth’s carbon cycle. The biological and physical complexity of these particles, together with the wide range of lengths and timescales that are involved in their motion, have made it exceedingly difficult to determine their dynamics in detail. Chajwa et al. used microscopic imaging to show that these particles universally exhibit a tail-like flow morphology that greatly influences their movement and how much carbon they sequester in the deep ocean.
Ecological speciation in Darwin’s finches: Ghosts of finches future
達爾文雀的生態物種形成：雀類未來的幽靈
▲ 作者：JEFFREY PODOS AND KATIE M. SCHROEDER
▲ 連結：
https://www.science.org/doi/10.1126/science.adj4478
▲ 摘要：
當我們想到一個物種適應環境變化時，通常會想到一個特征。然而，一個特征的改變可能會影響到其他特征。在Galapagos雀類中，已經證明幹旱會導致喙的大小和形狀發生變化，以響應種子資源的變化。
然而，鳥類不僅用喙吃飯，還用喙唱歌。Podos和Schroeder預測了鳥的大小如何隨著一系列幹旱而變化，並預測了它們會發出的歌曲。他們發現，在一系列模擬幹旱之後，這些歌曲的差異足夠大，以至於領地雄性鳥類不再辨識它們。
▲ Abstract：
When we think of a species adapting to environmental change, we mostly think about one trait. However, changes in one trait will likely affect others. In Galápagos finches, it has been shown that drought can lead to a change in bill size and shape in response to shifts in seed resources. However, birds do not just eat with their bills, they also sing with them. Podos and Schroeder predicted how bill size would change in response to a series of droughts and forecasted the songs that they would produce. They found that, after a series of simulated droughts, the songs differed enough that territorial male birds no longer recognized them.
化學 Chemistry
Catalytic asymmetric fragmentation of cyclopropanes
環丙烷催化不對稱裂解
▲ 作者：RAVINDRA KRUSHNAJI RAUT, SATOSHI MATSUTANI, FUXING SHI, SHUTA KATAOKA, MARGARETA POJE, BENJAMIN MITSCHKE, SATOSHI MAEDA, NOBUYA TSUJI , AND BENJAMIN LIST
▲ 連結：
https://www.science.org/doi/10.1126/science.adp9061
▲ 摘要：
過去半個世紀，有機化學家設計了許多催化劑，它們只能產生兩種可能的映像（對映體）產物中的一種。大多數情況下，這些催化劑依賴於氧或氮原子的結合位點。隨著反應的進行，缺乏這些位點的純碳氫化合物很難在空間上產生偏差。
研究者報道了一類手性酸，咪胺二磷酰亞胺酸，可以包裹對稱的環丙烷並催化其開環重排，以傳遞具有高對映選擇性的手性烯烴化合物。
▲ Abstract：
Over the past half-century, organic chemists have devised numerous catalysts that deliver just one of two possible mirror-image (enantiomeric) products. For the most part, these catalysts rely on binding sites with oxygen or nitrogen atoms; pure hydrocarbons lacking such sites are much harder to bias spatially as the reaction ensues. Raut et al. now report that a class of chiral acids, imidodiphosphorimidates, can envelop symmetrical cyclopropanes and catalyze their ring-opening rearrangement to deliver chiral olefinic compounds with high enantioselectivity.
Catalytic prenyl conjugate additions for synthesis of enantiomerically enriched PPAPs
催化戊烯基共軛加成物合成對映體富集PPAPs
▲ 作者：SHAWN NG, CASEY HOWSHALL, THANH NHAT HO, BINH KHANH MAI, YUEBIAO ZHOU, CAN QIN, KAI ZE TEE, PENG LIU, FILIPPO ROMITI, AND AMIR H. HOVEYDA
▲ 連結：
https://www.science.org/doi/10.1126/science.adr8612
▲ 摘要：
戊烯基是一種疏水的五碳片段，在生物化學和天然產物化學中廣泛存在。具有廣泛藥用價值的天然產品——多環聚戊烯基酰基間苯三酚（PPAPs），一直是多個合成研究的目標，但不對稱地引入戊烯基已被證明是一個持久的挑戰。
Ng等人報道了一種銅催化的方法，使不飽和酮戊酰化，從而獲得具有高對映選擇性的PPAP。該方法的關鍵是一種有機硼酸鹽試劑，硼在一個有點違反直覺的位置。
▲ Abstract：
The prenyl group is a hydrophobic five-carbon fragment common across a wide range of contexts in biochemistry and natural product chemistry. One extensive class of natural products of pharmaceutical interest, polycyclic polyprenylated acylphloroglucinols (PPAPs), has been the target of multiple synthetic studies, but the introduction of the prenyl groups asymmetrically has proven to be an enduring challenge. Ng et al. now report a copper-catalyzed method to prenylate unsaturated ketones and thereby access PPAPs with high enantioselectivity. Key to the method is an organoborate reagent with the boron in a somewhat counterintuitive position.
物理學 Physics
Direct optical measurement of intramolecular distances with angstrom precision
用埃精度直接光學測量分子內距離
▲ 作者：STEFFEN J. SAHL, JESSICA MATTHIAS, KAUSHIK INAMDAR, MICHAEL WEBER, TAUKEER A. KHAN, CHRISTIAN BRÜSER, STEFAN JAKOBS, STEFAN BECKER, CHRISTIAN GRIESINGER, AND STEFAN W. HELL
▲ 連結：
https://www.science.org/doi/10.1126/science.adj7368
▲ 摘要：
在納米尺度上直接測量距離對光學技術來說是一個挑戰，即使對那些使用亞繞射分辨率熒光顯微鏡的人來說也是如此。Sahl等人改進了一種名為MINFLUX的光學方法，可以精確測量1~10納米範圍內的分子內距離，而對於傾斜的分子，則可以測量1納米以下的分子內距離。他們使用聚脯胺酸尺，演示了具有已知個位數納米間距的熒光團的分辨率。
他們將這種方法套用於光活化染料標記的蛋白質的大分子間和大分子內測量，包括距離對目前的間接方法來說太短。成像實驗證明了該技術在研究細胞中蛋白質-蛋白質相互作用方面的潛力。
▲ Abstract：
Measuring distances directly at the nanometer scale is a challenge for optical techniques, even for those using subdiffraction-resolution fluorescence microscopy. Sahl et al. refined an optical approach called MINFLUX such that they could measure precise intramolecular distances in the 1- to 10-nanometer range and below 1 nanometer for molecules with a tilt. Using a polyproline ruler, the authors demonstrate resolution of fluorophores with known single-digit nanometer spacing. They applied this approach to inter- and intramacromolecular measurements of proteins labeled with photoactivatable dyes, including distances too short for current indirect methods. Imaging experiments demonstrated the potential of this technique to study protein-protein interactions in cells.
Polar and quasicrystal vortex observed in twisted-bilayer molybdenum disulfide
扭曲雙層二硫化鉬中觀察到極性和準晶渦旋
▲ 作者：CHI SHING TSANG, XIAODONG ZHENG, TONG YANG, ZHANGYUAN YAN, WEI HAN, LOK WING WONG, HAIJUN LIU, SHAN GAO, KA HO LEUNG, AND THUC HUE LY
▲ 連結：
https://www.science.org/doi/10.1126/science.adp7099
▲ 摘要：
對扭曲二硫化鉬（MoS2）雙分子層中電場的觀察揭示了與扭曲角有關的面內手性渦域。
Tsang等人使用四維掃描透射電子顯微鏡和第一性原理計算來確定局部極性域結構，這可能是由扭曲堆疊引起的電荷重新分配和小的平面內離子位移引起的。大扭角處可見馬賽克手性渦。一個12層的準晶體雙層具有復雜的渦旋圖案，可以透過在顯微鏡下置換層來調整。
▲ Abstract：
Observations of electric fields in twisted molybdenum disulfide bilayers have revealed in-plane chiral vortex domains that depend on the twist angle. Tsang et al. used four-dimensional scanning transmission electron microscopy (TEM) and first-principles calculations to determine local polar domain structures, which may arise from twist stacking-induced charge redistribution and small in-plane ionic displacements. Mosaic chiral vortex patterns were seen for large twist angles. A 12-fold quasicrystal bilayer had complex vortex patterns that could be tuned by displacing layers within the microscope.
