《科学》（20190322出版）一周论文导读

翻译 | 宗华

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

《科学》2019年3月22日，第6433期363卷

化学Chemistry

Activation of methane to CH₃⁺: A selective industrial route to methanesulfonic acid

甲烷活化成CH₃⁺：制取甲烷磺酸的选择性工业路线

▲ 作者：Christian Díaz-Urrutia, Timo Ott

▲ 链接：

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

▲ 摘要：

由于甲烷在很多反应环境中有过氧化倾向，因此直接将甲烷功能化为增值产品仍是一大挑战。磺化已成为实现必要选择性的一种有吸引力的方法。

在此，我们报告了仅利用两种反应物——甲烷和三氧化二硫生产甲烷磺酸（MSA）的实用过程。

结果表明，该过程的选择性和MSA产率均超过99%。以磺酰过氧化物衍生物为基础的亲电引发剂在超酸性条件下被质子化，从而产生高度亲电且能激活甲烷碳—氢键的氧原子。

力学研究为CH₃⁺作为关键中间体的形成提供了支撑。这种方法很容易扩展到串联的反应器，预计每年可生产多达20吨的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

双氮的还原耦合

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

▲ 链接：

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

▲ 摘要：

两种或更多双氮（N₂）分子的耦合在电离层的辐射条件下自然发生，并且可能在超高压或等离子体条件下合成实现。

然而，相对较低的N-N单键焓通常使强三键N2双原子级联不利，并且使氮链的分解成为常见的反应模体。

这里，我们报告了在近环境条件下两个N₂分子在有机硼介导下的惊人串联反应，并且形成了由一个[N₄]^2–链连接两个硼中心的复合物。该反应需要在一个步骤中还原耦合两个低价硼结合的N₂单元。这个络合物和链两端质子化的衍生物都用晶体学方法进行了表征。

▲ 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 N₂ diatomic 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 N₂ units in a single step. Both this complexand a derivative protonated at both ends of the chain were characterized crystallographically.

 

生物学Biology

Social genes are selection hotspots in kingroups of a soil microbe

社会基因是土壤微生物亲缘群体的选择热点

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

▲ 链接：

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

▲ 摘要：

包括动物社会、有机体和微生物群在内的合作系统的构成反映了它们的过去，并塑造了未来的进化。

然而，很多多单元系统中的基因组多样性仍未得到明确描述。这限制了理解和比较其进化特征的能力。

我们对来自6个多细胞子实体的合作型黄黏球菌的120株天然分离物进行了基因组和社会表型分析。每个子实体由从一个独特的最近祖先辐射出来的多个谱系组成。基因组进化集中在与社会表型中进化变化相关的选择热点上。

同义突变表明，同一子实体内的亲缘谱系往往在100多代以前就开始从一个共同的祖先分化出来。

因此，选择似乎促进了在当地相互作用的长期历史中保持在一起的亲缘谱系的地方性多样化，从而加强了社会共同进化。

▲ 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

兔子群体对黏液瘤病毒的平行适应

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

▲ 链接：

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

▲ 摘要：

20世纪50年代，黏液瘤病毒被释放到澳大利亚和欧洲的欧洲兔子种群中，导致后者大量死亡以及抗药性的迅速进化。

我们通过比较在这场流行性疾病前后收集的兔子外显子组，研究了耐药性的遗传基础。我们发现了一个强大的平行进化模式——在澳大利亚、法国和英国，进化会选择有利于相同等位基因的固定基因变异。其中，很多变化发生在免疫相关基因中，从而支持了耐药的多基因基础。

我们通过实验验证了若干个基因在病毒复制中的作用，并且证实对干扰素蛋白的选择增加了该蛋白的抗病毒效果。

▲ 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

高果糖玉米糖浆能促进小鼠肠道肿瘤的生长

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

▲ 链接：

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

▲ 摘要：

过量饮用含高果糖玉米糖浆（HFCS）的饮料会导致肥胖，并增加患结肠直肠癌的风险。HFCS是否直接导致肿瘤发生尚不清楚。

我们研究了每日服用HFCS对易发展为肠道肿瘤的腺瘤性息肉病（APC）突变小鼠的影响。在没有肥胖和代谢综合征的情况下，服用HFCS的小鼠的肿瘤大小和肿瘤分级显著增加。HFCS分别增加了肠道腔内和血清中果糖和葡萄糖的浓度，并且肿瘤运输了这两种糖。

在肿瘤内部，果糖被转化为果糖-1-磷酸，导致糖酵解的激活和支持肿瘤生长的脂肪酸合成的增加。

这些小鼠研究支持了这样的假设，即饮食中葡萄糖和果糖的结合，即使是在中等剂量下，也能增强肿瘤的发生。

▲ 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

低温保存的青春期前恒河猴睾丸的自体移植可产生精子和后代

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

▲ 链接：

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

▲ 摘要：

睾丸组织冷冻保存是一种在青春期前患者开始针对癌症或其他疾病的性腺毒性治疗前为保持其生育能力而采用的实验方法。

这里，我们证明低温保存的青春期前睾丸组织可被自体移植到被阉割的青春期恒河猴的背部皮肤或阴囊皮肤下，发育成熟并产生功能性精子。

在8~12个月的观察期间，移植物不断生长并产生睾酮。完整的精子在恢复时的所有移植物中均得到证实。

移植产生的精子能使恒河猴的卵母细胞受精，从而促成着床前胚胎发育、怀孕和健康雌性恒河猴的诞生。

不过，只有在未阉割的受试恒河猴中也能得到类似结果后，睾丸组织移植或许才可应用于临床。

▲ 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.

 

物理学Physics

Inverse-designed metastructures that solve equations

求解方程的逆设计元结构

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

▲ 链接：

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

▲ 摘要：

元结构有可能给空间域光学模拟计算领域带来新的转折：从自由空间和庞大的系统迁移到概念上的波长大小元素。

我们介绍了一种利用单色电磁场求解积分方程的超材料平台。对于任意波作为与给定积分算子相关的方程的输入函数，该方程的解作为复值输出电磁场产生。

我们的方法是在微波频率下通过求解一个通用积分方程，并利用一组波导作为输入和输出到所设计元结构进行实验证明。

通过在超材料平台上利用亚波长尺度的光—物质相互作用，我们基于波和材料的模拟计算机可能提供了一种实现芯片尺度、快速和可集成计算元素的途径。

▲ 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.

考古学Archeology

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

清江生物群——中国南方寒武纪早期伯尔吉斯页岩型化石的化石库

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

▲ 链接：

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

▲ 摘要：

伯尔吉斯页岩型化石的化石库（Lagerstätten）为解释寒武纪大爆发的生物模式和规模提供了最好的证据。

这里，我们报告了一个来自中国南方的化石库——清江生物群（拥有约5.18亿年历史）。其主要是来自远端陆架的软体类群。

清江生物群以不稳定有机特征的原始碳质保存、新分类群的高比例（约53%）和初步的分类学多样性为特征，表明其可与澄江和伯尔吉斯页岩生物群相媲美。

清江生物群的特征包括拥有诸如水母类、息肉类等丰富的刺胞动物；新的类群类似于现存的动吻动物；拥有丰富的幼虫或幼体。这种独特的构成有望为我们提供关于寒武纪生态系统跨环境梯度演化的洞见。

▲ Abstract

Burgess Shale–type fossil Lagerstätten provide the best evidence for deciphering the biotic patterns and magnitude of the Cambrian explosion. Here, we report a Lagerstätte 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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