《科學》（20231201出版）一周論文導讀

原文地址：http://news.sciencenet.cn/htmlnews/2023/12/513525.shtm

編譯 | 李言

Science, 1 DEC 2023, Volume 382 Issue 6674

《科學》2023年12月1日，第382卷，6674期

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生物學Biology

Two teosintes made modern maize

兩種大芻草為現代玉米的祖先

▲ 作者：NING YANG, YUEBIN WANG et al.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adg8940

▲ 摘要：

玉米的起源是近一個世紀以來激烈爭論的話題，但目前的遺傳模型和早期的考古模型都不能解釋現有的全部數據，近期的一些研究強調了野生近親墨西哥高原大芻草亞種的潛在貢獻。

我們的群體遺傳分析表明，現代玉米的起源可以追溯到古代玉米和大芻草亞種之間的混合，這一過程始于馴化開始4000年后的墨西哥高地。我們發現，無論是在個體位點還是在農藝性狀基礎上的加性遺傳變異上，基因滲透都是玉米多樣性的關鍵組成部分。

我們的研究結果澄清了現代玉米的起源，并提出了關于在玉米在整個美洲擴散的人為機制的新問題。

▲ Abstract：

The origins of maize were the topic of vigorous debate for nearly a century, but neither the current genetic model nor earlier archaeological models account for the totality of available data, and recent work has highlighted the potential contribution of a wild relative, Zea mays ssp. mexicana. Our population genetic analysis reveals that the origin of modern maize can be traced to an admixture between ancient maize and Zea mays ssp. mexicana in the highlands of Mexico some 4000 years after domestication began. We show that variation in admixture is a key component of maize diversity, both at individual loci and for additive genetic variation underlying agronomic traits. Our results clarify the origin of modern maize and raise new questions about the anthropogenic mechanisms underlying dispersal throughout the Americas.

Nesting chinstrap penguins accrue large quantities of sleep through seconds-long microsleeps

筑巢的帽帶企鵝能通過幾秒鐘的微睡眠積累大量的睡眠

▲ 作者：P.-A. LIBOUREL, W. Y. LEE et al.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adh0771

▲ 摘要：

我們研究了野生帽帶企鵝在海上和在南極洲筑巢時，不斷暴露于蛋捕食者和其他企鵝的攻擊下的腦電圖顯示的睡眠情況。這些企鵝每天打盹超過1萬次，雙腦和單腦慢波睡眠都有，平均持續時間僅為4秒，但累積的睡眠時間超過11小時。

成功繁殖的企鵝在微睡眠的表現表明，睡眠的好處是可以逐漸積累的。

▲ Abstract：

We investigated electroencephalographically defined sleep in wild chinstrap penguins, at sea and while nesting in Antarctica, constantly exposed to an egg predator and aggression from other penguins. The penguins nodded off >10,000 times per day, engaging in bouts of bihemispheric and unihemispheric slow-wave sleep lasting on average only 4 seconds, but resulting in the accumulation of >11 hours of sleep for each hemisphere. The investment in microsleeps by successfully breeding penguins suggests that the benefits of sleep can accrue incrementally.

天文學Astronomy

A Neptune-mass exoplanet in close orbit around a very low-mass star challenges formation models

一顆海王星大小的系外行星在一顆質量極低的恒星的近軌道上運行，挑戰了形成模型

▲ 作者：GUDMUNDUR STEFáNSSON, SUVRATH MAHADEVAN et al.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.abo0233

▲ 摘要：

我們利用徑向速度觀測發現了一顆海王星質量的系外行星，它圍繞著LHS 3154運行，這顆恒星的質量比太陽小9倍。這顆系外行星的軌道周期為3.7天，其最小質量是地球質量的13.2倍。

我們通過模擬表明，高行星—恒星質量比（>3.5 × 10?3）不是核心吸積理論或行星形成引力不穩定性理論的預期結果。在核心吸積模擬中，我們表明，只有當原行星盤的塵埃質量比通常在非常低質量的恒星周圍觀察到的大一個數量級時，才會形成海王星質量等級的近距離行星。

▲ Abstract：

We used radial velocity observations to detect a Neptune-mass exoplanet orbiting LHS 3154, a star that is nine times less massive than the Sun. The exoplanet’s orbital period is 3.7 days, and its minimum mass is 13.2 Earth masses. We used simulations to show that the high planet-to-star mass ratio (>3.5 × 10?3) is not an expected outcome of either the core accretion or gravitational instability theories of planet formation. In the core-accretion simulations, we show that close-in Neptune-mass planets are only formed if the dust mass of the protoplanetary disk is an order of magnitude greater than typically observed around very low-mass stars.

環境科學Environmental Science

State dependence of CO2 forcing and its implications for climate sensitivity

二氧化碳作用力的狀態依賴性及其對氣候敏感性的影響

▲ 作者：HAOZHE HE, RYAN J. KRAMER et al.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.abq6872

▲ 摘要：

在此，我們表明IRF2×CO2不是常數，而是取決于氣候基礎狀態，二氧化碳每增加一倍，IRF2×CO2就增加約25%。并且，由于平流層上部的冷卻，IRF2×CO2自工業化前時代以來增加了約10%，這意味著氣候敏感性的比例增加。

這種對基本狀態的依賴也解釋了IRF2×CO2中大約一半的模式間傳播問題，這一問題在氣候模型中持續爭論了近30年。

▲ Abstract：

Here, we show that the IRF2×CO2 is not constant, but rather depends on the climatological base state, increasing by about 25% for every doubling of CO2, and has increased by about 10% since the preindustrial era primarily due to the cooling within the upper stratosphere, implying a proportionate increase in climate sensitivity. This base-state dependence also explains about half of the intermodel spread in IRF2×CO2, a problem that has persisted among climate models for nearly three decades.

化學Chemistry

Boryl radical catalysis enables asymmetric radical cycloisomerization reactions

硼自由基催化使不對稱環異構化反應成為可能

▲ 作者：CHANG-LING WANG, JIE WANG et al.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adg1322

▲ 摘要：

在這項研究中，我們報告了一個手性氮雜環卡賓（NHC）連接的硼基自由基家族作為催化劑，可以催化不對稱自由基環異構化反應。自由基催化劑可以由易于制備的手性硼烷配合物生成，并且手性NHC組分的廣泛可用性為立體化學控制提供了幫助。

該機理研究支持一個由硼基自由基加成、氫原子轉移、環化和消除硼基自由基催化劑組成的催化循環，其中手性NHC亞基決定了自由基環化的對映選擇性。這種催化作用允許從簡單的起始材料不對稱構造有價值的手性雜環產物。

▲ Abstract：

In this work, we report a family of chiral N-heterocyclic carbene (NHC)–ligated boryl radicals as catalysts that enable catalytic asymmetric radical cycloisomerization reactions. The radical catalysts can be generated from easily prepared NHC-borane complexes, and the broad availability of the chiral NHC component provides substantial benefits for stereochemical control. Mechanistic studies support a catalytic cycle comprising a sequence of boryl radical addition, hydrogen atom transfer, cyclization, and elimination of the boryl radical catalyst, wherein the chiral NHC subunit determines the enantioselectivity of the radical cyclization. This catalysis allows asymmetric construction of valuable chiral heterocyclic products from simple starting materials.

材料科學Materials Science

3D microscopy at the nanoscale reveals unexpected lattice rotations in deformed nickel

納米級三維顯微鏡揭示了變形鎳中意外的晶格旋轉

▲ 作者：QIONGYAO HE, S?REN SCHMIDT et al.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adj2522

▲ 摘要：

在原位納米力學測試之前和之后，我們都通過透射電子顯微鏡的三維定向映射來跟蹤納米鎳中單個晶粒的旋轉。許多較大尺寸的顆粒經歷了意外的晶格旋轉，我們認為這是由于卸載過程中的旋轉逆轉。

這種固有的可逆旋轉源于背應力驅動的位錯滑移過程，較大的晶粒在其中更為活躍。研究結果為納米顆粒金屬的基本變形機制提供了見解，并將有助于指導材料設計和工程應用策略。

▲ Abstract：