《科學》（20190322出版）一周論文導讀

翻譯 | 宗華

Science, 22 MARCH 2019, Vol. 363, No. 6433

《科學》2019年3月22日，第6433期363卷

化學Chemistry

Activation of methane toCH₃⁺: A selective industrial route to methanesulfonic acid

甲烷活化成CH₃⁺：製取甲烷磺酸的選擇性工業路線

作者：Christian Díaz-Urrutia, Timo Ott

鏈接：

http://science.sciencemag.org/content/363/6433/1326

摘要：

由於甲烷在很多反應環境中有過氧化傾向，因此直接將甲烷功能化為增值產品仍是一大挑戰。磺化已成為實現必要選擇性的一種有吸引力的方法。

在此，我們報告了僅利用兩種反應物——甲烷和三氧化二硫生產甲烷磺酸（MSA）的實用過程。

結果表明，該過程的選擇性和MSA產率均超過99%。以磺醯過氧化物衍生物為基礎的親電引發劑在超酸性條件下被質子化，從而產生高度親電且能激活甲烷碳—氫鍵的氧原子。

力學研究為CH₃⁺作為關鍵中間體的形成提供了支撐。這種方法很容易擴展到串聯的反應器，預計每年可生產多達20噸的MSA。

Abstract

Direct methane functionalization to value-added products remains a challenge because of the propensity for overoxidation in many reaction environments. Sulfonation has emerged as an attractive approach for achieving the necessary selectivity. Here, we report a practical process for the production of methanesulfonic acid (MSA) from only two reactants: methane and sulfur trioxide. We have achieved >99% selectivity and yield of MSA. The electrophilic initiator based on a sulfonyl peroxide derivative is protonated under superacidic conditions, producing a highly electrophilic oxygen atom capable of activating a C–H bond of methane. Mechanistic studies support the formation of CH₃⁺as akey intermediate. This method is readily scalable with reactors connected in series for prospective production of up to 20 metric tons per year of MSA.

The reductive coupling of dinitrogen

雙氮的還原耦合

作者：Marc-André Légaré, Maximilian Rang, Guillaume Bélanger-Chabot, et al

鏈接：

http://science.sciencemag.org/content/363/6433/1329

摘要：

兩種或更多雙氮（N₂）分子的耦合在電離層的輻射條件下自然發生，並且可能在超高壓或等離子體條件下合成實現。

然而，相對較低的N-N單鍵焓通常使強三鍵N2雙原子級聯不利，並且使氮鏈的分解成為常見的反應模體。

這裡，我們報告了在近環境條件下兩個N₂分子在有機硼介導下的驚人串聯反應，並且形成了由一個[N₄]^2–鏈連接兩個硼中心的複合物。該反應需要在一個步驟中還原耦合兩個低價硼結合的N₂單元。這個絡合物和鏈兩端質子化的衍生物都用晶體學方法進行了表徵。

Abstract

The coupling of two or more molecules of dinitrogen (N₂) occurs naturally under the radiative conditionspresent in the ionosphere and may be achieved synthetically under ultrahigh pressure or plasma conditions. However, the comparatively low N–N single-bondenthalpy generally renders the catenation of the strongly triple-bonded N₂diatomic unfavorable and the decomposition of nitrogen chains a common reaction motif. Here, we report the surprising organoboron-mediated catenation of two N₂ molecules under near-ambient conditions to form a complex in which a [N₄]^2– chain bridges two boron centers. The reaction entails reductive coupling of two hypovalent-boron-bound N₂units in a single step. Both this complexand a derivative protonated at both ends of the chain were characterized crystallographically.

生物學Biology

Social genes are selection hotspots in kingroups of a soil microbe

社會基因是土壤微生物親緣群體的選擇熱點

作者：Sébastien Wielgoss*, Rebekka Wolfensberger, Lei Sun,

鏈接：

http://science.sciencemag.org/content/363/6433/1342

摘要：

包括動物社會、有機體和微生物群在內的合作系統的構成反映了它們的過去，並塑造了未來的進化。

然而，很多多單元系統中的基因組多樣性仍未得到明確描述。這限制了理解和比較其進化特徵的能力。

我們對來自6個多細胞子實體的合作型黃黏球菌的120株天然分離物進行了基因組和社會表型分析。每個子實體由從一個獨特的最近祖先輻射出來的多個譜系組成。基因組進化集中在與社會表型中進化變化相關的選擇熱點上。

同義突變表明，同一子實體內的親緣譜系往往在100多代以前就開始從一個共同的祖先分化出來。

因此，選擇似乎促進了在當地相互作用的長期歷史中保持在一起的親緣譜系的地方性多樣化，從而加強了社會共同進化。

Abstract

The composition of cooperative systems, including animal societies, organismal bodies, and microbial groups, reflects their past and shapes their future evolution. However, genomic diversity within many multiunit systems remains uncharacterized, limiting our ability to understand and compare their evolutionary character. We have analyzed genomicand social-phenotype variation among 120 natural isolates of the cooperative bacterium Myxococcus xanthus derived from six multicellular fruiting bodies. Eachfruiting body was composed of multiple lineages radiating from a unique recent ancestor. Genomic evolution was concentrated in selection hotspots associated with evolutionary change in social phenotypes. Synonymous mutations indicated that kin lineages within the same fruiting body often first diverged from a common ancestor more than 100 generations ago. Thus, selection appears to promote endemic diversification of kin lineages that remain together over long histories of local interaction, thereby potentiating social coevolution.

Parallel adaptation of rabbit populations to myxoma virus

兔子群體對黏液瘤病毒的平行適應

作者：Joel M. Alves, Miguel Carneiro, Jade Y. Cheng, et al

鏈接：

http://science.sciencemag.org/content/363/6433/1319

摘要：

20世紀50年代，黏液瘤病毒被釋放到澳大利亞和歐洲的歐洲兔子種群中，導致後者大量死亡以及抗藥性的迅速進化。

我們通過比較在這場流行性疾病前後收集的兔子外顯子組，研究了耐藥性的遺傳基礎。我們發現了一個強大的平行進化模式——在澳大利亞、法國和英國，進化會選擇有利於相同等位基因的固定基因變異。其中，很多變化發生在免疫相關基因中，從而支持了耐葯的多基因基礎。

我們通過實驗驗證了若干個基因在病毒複製中的作用，並且證實對干擾素蛋白的選擇增加了該蛋白的抗病毒效果。

Abstract

In the 1950s the myxoma virus was released into European rabbit populations in Australia and Europe, decimating populations and resulting in the rapid evolution of resistance. We investigated the genetic basis of resistance by comparing the exomes of rabbits collected before and after the pandemic. We found a strong pattern of parallel evolution, with selection on standing genetic variation favoring the same alleles inAustralia, France, and the United Kingdom. Many of these changes occurred inimmunity-related genes, supporting a polygenic basis of resistance. We experimentally validated the role of several genes in viral replication and showed that selection acting on an interfer on protein has increased the protein』s antiviral effect.

健康Health

High-fructose corn syrup enhances intestinal tumor growth in mice

高果糖玉米糖漿能促進小鼠腸道腫瘤的生長

作者：Marcus D. Goncalves, Changyuan Lu, Jordan Tutnauer, et al

鏈接：

http://science.sciencemag.org/content/363/6433/1345

摘要：

過量飲用含高果糖玉米糖漿（HFCS）的飲料會導致肥胖，並增加患結腸直腸癌的風險。HFCS是否直接導致腫瘤發生尚不清楚。

我們研究了每日服用HFCS對易發展為腸道腫瘤的腺瘤性息肉病（APC）突變小鼠的影響。在沒有肥胖和代謝綜合征的情況下，服用HFCS的小鼠的腫瘤大小和腫瘤分級顯著增加。HFCS分別增加了腸道腔內和血清中果糖和葡萄糖的濃度，並且腫瘤運輸了這兩種糖。

在腫瘤內部，果糖被轉化為果糖-1-磷酸，導致糖酵解的激活和支持腫瘤生長的脂肪酸合成的增加。

這些小鼠研究支持了這樣的假設，即飲食中葡萄糖和果糖的結合，即使是在中等劑量下，也能增強腫瘤的發生。

Abstract

Excessive consumption of beverages sweetened with high-fructose corn syrup (HFCS) is associated with obesity and with an increased risk of colorectal cancer. Whether HFCS contributes directly to tumorigenesis is unclear. We investigated the effects of daily oral administration of HFCS in adenomatous polyposis coli (APC) mutant mice, which are predisposed to develop intestinal tumors. The HFCS-treated mice showed a substantial increase in tumor size and tumor grade in the absence of obesityand metabolic syndrome. HFCS increased the concentrations of fructose and glucose in the intestinal lumen and serum, respectively, and the tumors transported both sugars. Within the tumors, fructose was converted tofructose-1-phosphate, leading to activation of glycolysis and increased synthesis of fatty acids that support tumor growth. These mouse studies supportthe hypothesis that the combination of dietary glucose and fructose, even at amoderate dose, can enhance tumorigenesis.

Autologous grafting of cryopreserved prepubertal rhesus testis produces sperm and offspring

低溫保存的青春期前恆河猴睾丸的自體移植可產生精子和後代

作者：Adetunji P. Fayomi, Karen Peters, Meena Sukhwani, et al

鏈接：

http://science.sciencemag.org/content/363/6433/1314

摘要：

睾丸組織冷凍保存是一種在青春期前患者開始針對癌症或其他疾病的性腺毒性治療前為保持其生育能力而採用的實驗方法。

這裡，我們證明低溫保存的青春期前睾丸組織可被自體移植到被閹割的青春期恆河猴的背部皮膚或陰囊皮膚下，發育成熟併產生功能性精子。

在8~12個月的觀察期間，移植物不斷生長併產生睾酮。完整的精子在恢復時的所有移植物中均得到證實。

移植產生的精子能使恆河猴的卵母細胞受精，從而促成著床前胚胎髮育、懷孕和健康雌性恆河猴的誕生。

不過，只有在未閹割的受試恆河猴中也能得到類似結果後，睾丸組織移植或許才可應用於臨床。

Abstract

Testicular tissue cryopreservation is an experimental method to preserve the fertility of prepubertal patients before they initiate gonadotoxic therapies for cancer or other conditions. Here we provide the proof of principle that cryopreserved prepubertal testicular tissues can be autologously grafted under the back skin or scrotal skin of castrated pubertal rhesus macaques and matured to produce functional sperm. During the 8- to 12-month observation period, grafts grew and produced testosterone. Complete spermatogenesis was confirmed in all grafts at the time of recovery. Graft-derived sperm were competent to fertilize rhesus oocytes, leading to preimplantation embryo development, pregnancy, and the birth of a healthy female baby. Pending the demonstration that similar results are obtained in noncastrated recipients, testicular tissue grafting may be appliedin the clinic.

物理學Physics

Inverse-designed metastructures that solve equations

求解方程的逆設計元結構

作者：Nasim Mohammadi Estakhri, Brian Edwards, Nader Engheta, et al

鏈接：

http://science.sciencemag.org/content/363/6433/1333

摘要：

元結構有可能給空間域光學模擬計算領域帶來新的轉折：從自由空間和龐大的系統遷移到概念上的波長大小元素。

我們介紹了一種利用單色電磁場求解積分方程的超材料平台。對於任意波作為與給定積分運算元相關的方程的輸入函數，該方程的解作為復值輸出電磁場產生。

我們的方法是在微波頻率下通過求解一個通用積分方程，並利用一組波導作為輸入和輸出到所設計元結構進行實驗證明。

通過在超材料平台上利用亞波長尺度的光—物質相互作用，我們基於波和材料的模擬計算機可能提供了一種實現晶元尺度、快速和可集成計算元素的途徑。

Abstract

Metastructures hold the potential to bring a new twist to the field of spatial-domain optical analog computing: migratingfrom free-space and bulky systems into conceptually wavelength-sized elements.We introduce a metamaterial platform capable of solving integral equations using monochromatic electromagnetic fields. For an arbitrary wave as the input function to an equation associated with a prescribed integral operator, the solution of such an equation is generated as a complex-valued output electromagnetic field. Our approach is experimentally demonstrated at microwave frequencies through solving a generic integral equation and using a set of waveguides as the input and output to the designed metastructures. By exploiting subwavelength-scale light-matter interactions in a metamaterial platform, our wave-based, material-based analog computer may provide a route to achieve chip-scale, fast, and integrable computing elements.

考古學Archeology

The Qingjiang biota—A Burgess Shale–type fossil Lagerst?tte from the early Cambrian of South China

清江生物群——中國南方寒武紀早期伯爾吉斯頁岩型化石的化石庫

作者：Dongjing Fu, Guanghui Tong, Tao Dai, Wei Liu, et al

鏈接：

http://science.sciencemag.org/content/363/6433/1338

摘要：

伯爾吉斯頁岩型化石的化石庫（Lagerst?tten）為解釋寒武紀大爆發的生物模式和規模提供了最好的證據。

這裡，我們報告了一個來自中國南方的化石庫——清江生物群（擁有約5.18億年歷史）。其主要是來自遠端陸架的軟體類群。

清江生物群以不穩定有機特徵的原始碳質保存、新分類群的高比例（約53%）和初步的分類學多樣性為特徵，表明其可與澄江和伯爾吉斯頁岩生物群相媲美。

清江生物群的特徵包括擁有諸如水母類、息肉類等豐富的刺胞動物；新的類群類似於現存的動吻動物；擁有豐富的幼蟲或幼體。這種獨特的構成有望為我們提供關於寒武紀生態系統跨環境梯度演化的洞見。

Abstract

Burgess Shale–type fossil Lagerst?tten provide the best evidence for deciphering the biotic patterns and magnitude of the Cambrian explosion. Here, we report a Lagerst?tte from South China, the Qingjiang biota (~518 million years old), which is dominated by soft-bodied taxa from a distal shelf setting. The Qingjiang biota is distinguished by pristine carbonaceous preservation of labile organic features, a very high proportion of new taxa (~53%), and preliminary taxonomic diversity that suggests it could rival the Chengjiang and Burgess Shale biotas. Defining aspects of the Qingjiang biota include a high abundance of cnidarians, including both medusoid and polypoid forms; new taxa resembling extant kinorhynchs; and abundant larval or juvenile forms. This distinctive composition holds promisefor providing insights into the evolution of Cambrian ecosystems across environmental gradients.

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