《自然》（20240919出版）一周論文導讀

編譯|李言

Nature,19 September 2024, Volume 633 Issue 8030

《自然》，2024年9月19日，第633卷，8030期

化學Chemistry

Growth of complete ammonia oxidizers on guanidine

完全氨氧化劑在胍上的生長

▲ 作者：Marton Palatinszky, Craig W. Herbold et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-07832-z

▲摘要：

在此，我們證明了完全氨氧化劑硝化螺旋菌和大多數其他comammox微生物可以以胍為唯一的能量、還原劑和氮源生長。蛋白質組學、酶動力學和晶體結構的研究表明，它是一種真正的胍酶。含comammox的農業土壤和污水處理廠微生物組的培養實驗表明，胍是環境中硝化作用的底物。胍作為comammox生長底物的鑒定顯示了這些全球重要硝化菌的出乎意料的生態位，并為它們的分離提供了機會。

▲ Abstract：

Here we show that the complete ammonia oxidizer (comammox) Nitrospira inopinata and probably most other comammox microorganisms can grow on guanidine as the sole source of energy, reductant and nitrogen. Proteomics, enzyme kinetics and the crystal structure of a N. inopinata guanidinase homologue demonstrated that it is a bona fide guanidinase. Incubation experiments with comammox-containing agricultural soil and wastewater treatment plant microbiomes suggested that guanidine serves as substrate for nitrification in the environment. The identification of guanidine as a growth substrate for comammox shows an unexpected niche of these globally important nitrifiers and offers opportunities for their isolation.

物理學Physics

Dynamic transition and Galilean relativity of current-driven skyrmions

電流驅動斯格明子的動態躍遷和伽利略相對性

▲ 作者：Max T. Birch, Ilya Belopolski et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-07859-2

▲摘要：

在這里，我們報告了Gd₂PdSi₃中由其顯著的拓撲霍爾效應（THE）所促進的斯格明子晶格（SkL）運動引發的新興電動力學現象。隨著電流激勵的增加，我們觀察到SkL運動從釘住狀態到蠕變狀態，最后到流動狀態的動態轉變，其中THE完全被抑制。

我們認為，即使在如目前的化合物的復雜多帶系統中，也可以在流動狀態中恢復完全抵消所需要的伽利略相對性。此外，我們觀察到的電壓足夠大，可以實時測量SkL的速度—電流曲線。該曲線顯示SkL在蠕變狀態下的慣性運動，表現為斯格明子速度的電流滯后現象。

▲ Abstract：

Here we report the emergent electrodynamics induced by SkL motion in Gd₂PdSi₃, facilitated by its giant THE. With increasing current excitation, we observe the dynamic transition of the SkL motion from the pinned to creep regime and finally to the flow regime, in which the THE is totally suppressed. We argue that the Galilean relativity required for the total cancellation of the THE may be generically recovered in the flow regime, even in complex multiband systems such as the present compound. Moreover, the observed THE voltages are large enough to enable real-time measurement of the SkL velocity–current profile, which shows the inertial-like motion of the SkL in the creep regime, appearing as the current hysteresis of the skyrmion velocity.

醫學Medicine

Frontostriatal salience network expansion in individuals in depression

抑郁癥患者的額紋狀體顯著網絡擴展

▲ 作者：Charles J. Lynch, Immanuel G. Elbau et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-07805-2

▲摘要：

在此，使用精確的函數映射和幾個深度采樣的個體樣本，我們發現大多數抑郁癥患者的額紋狀體顯著性網絡在皮質中擴展了近兩倍。這種效應在幾個樣本中是可復制的，主要是由網絡邊界移動引起的，在不同的個體中發生了三種不同的入侵模式。

隨著時間的推移，顯著性網絡擴展是穩定的，不受情緒狀態的影響，在青春期后期抑郁發作前的兒童中可以檢測到。在1.5年的時間里，我們對患者進行了多達62次的縱向分析，發現了額紋狀體回路的連通性變化，追蹤了特定癥狀的波動，并預測了未來的快感缺乏癥狀。

總之，這些發現確定了一種特征樣的大腦網絡拓撲結構。它可能帶來抑郁癥的風險，以及額紋狀體回路中情緒狀態依賴性連接的變化，這些變化可以預測抑郁癥狀隨時間的出現和緩解。

▲ Abstract：

Here, using precision functional mapping and several samples of deeply sampled individuals, we found that the frontostriatal salience network is expanded nearly twofold in the cortex of most individuals with depression. This effect was replicable in several samples and caused primarily by network border shifts, with three distinct modes of encroachment occurring in different individuals. Salience network expansion was stable over time, unaffected by mood state and detectable in children before the onset of depression later in adolescence. Longitudinal analyses of individuals scanned up to 62 times over 1.5 years identified connectivity changes in frontostriatal circuits that tracked fluctuations in specific symptoms and predicted future anhedonia symptoms. Together, these findings identify a trait-like brain network topology that may confer risk for depression and mood-state-dependent connectivity changes in frontostriatal circuits that predict the emergence and remission of depressive symptoms over time.

地球科學Earth Science

Decoding drivers of carbon flux attenuation in the oceanic biological pump

解碼海洋生物泵中碳通量衰減的驅動因素

▲ 作者：M. Bressac, E. C. Laurenceau-Cornec et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-07850-x

▲摘要：

在此，我們展示了C-RESPIRE的原位實驗結果。C-RESPIRE是一種部署在多個中層深度的雙粒子攔截器和培養箱，用于測量微生物介導的顆粒有機碳（POC）通量衰減。

我們發現，在6個不同的海洋體系中，即POC通量的30倍范圍內，顆粒附著微生物的降解為通量衰減的7%—29%，這意味著浮游動物在通量衰減中發揮了更大的影響作用。微生物再礦化，標準化到POC通量，在不同的地點和深度范圍20倍，在高POC通量下速率最低。

高達三倍變化的垂直趨勢與低緯度地區強烈的溫度梯度有關。與之相反，在中高緯度地區，溫度的影響較小，而垂直趨勢可能由顆粒生物化學、破碎化和微生物生態生理共同決定。馬丁曲線的解構揭示了驅動微生物介導的POC通量衰減的基本機制。

▲ Abstract：

Here we present in situ experimental findings from C-RESPIRE, a dual particle interceptor and incubator deployed at multiple mesopelagic depths, measuring microbially mediated POC flux attenuation. We find that across six contrasting oceanic regimes, representing a 30-fold range in POC flux, degradation by particle-attached microbes comprised 7–29 per cent of flux attenuation, implying a more influential role for zooplankton in flux attenuation. Microbial remineralization, normalized to POC flux, ranged by 20-fold across sites and depths, with the lowest rates at high POC fluxes. Vertical trends, of up to threefold changes, were linked to strong temperature gradients at low-latitude sites. In contrast, temperature played a lesser role at mid- and high-latitude sites, where vertical trends may be set jointly by particle biochemistry, fragmentation and microbial ecophysiology. This deconstruction of the Martin curve reveals the underpinning mechanisms that drive microbially mediated POC flux attenuation across oceanic provinces.

Observation-constrained projections reveal longer-than-expected dry spells

預測顯示干旱期將長于預期

▲ 作者：Irina Y. Petrova, Diego G. Miralles et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-07887-y

▲摘要：

在此，我們表明使用新提出的緊急約束（EC）來約束模型預測，可以在全球范圍內將核心干旱指標——最長年度干旱期（LAD）——預測的不確定性降低10%—26%。經EC校正后的預測結果顯示，與目前預測的未來作用力情景相比，LAD的平均增幅將高出42%—44%。這些結果表明，到本世紀末，全球平均僅陸地的LAD可能比目前預計的要長10天。

利用兩代氣候模式，我們進一步揭示了歷史LAD偏差影響預估LAD增加幅度的全球區域，并探討了陸地—大氣反饋在其中的作用。我們的研究結果揭示了一些地區的社會和生態系統可能面臨比預期更高、更早的干旱風險，并指出了當前一代氣候模型中存在偏差的可能機制。

▲ Abstract：

Here we show that constraining model projections with observations using a newly proposed emergent constraint (EC) reduces the uncertainty in predictions of a core drought indicator, the longest annual dry spell (LAD), by 10–26% globally. Our EC-corrected projections reveal that the increase in LAD will be 42–44% greater, on average, than ‘mid-range’ or ‘high-end’ future forcing scenarios currently indicate. These results imply that by the end of this century, the global mean land-only LAD could be 10 days longer than currently expected. Using two generations of climate models, we further uncover global regions for which historical LAD biases affect the magnitude of projected LAD increases, and we explore the role of land–atmosphere feedbacks therein. Our findings reveal regions with potentially higher- and earlier-than-expected drought risks for societies and ecosystems, and they point to possible mechanisms underlying the biases in the current generation of climate models.

A climate threshold for ocean deoxygenation during the Early Cretaceous

白堊紀早期海洋脫氧的氣候閾值

▲ 作者：Kohen W. Bauer, N. Ryan McKenzie et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-07876-1

▲摘要：

在此，我們的研究顯示，在白堊紀大洋缺氧事件（OAE1a）期間海洋快速脫氧與火山二氧化碳排放和相關氣候閾值的跨越有關。此后，硅酸鹽風化反饋和氣候恢復的緩慢步伐將再氧化的延遲事件大于1百萬年。在OAE1a結束時，重新越過這個閾值并使得海洋再氧化。

然而，在OAE1a之后，地球系統保持足夠的溫暖，以至于軌道驅動的氣候動力學導致海洋在大約10億年的時間尺度上繼續循環脫氧，并持續了1百萬年。因此，我們的結果暗示了火山作用、風化作用和海洋氧含量之間的緊密耦合，這種耦合以氣候閾值為特征。

▲ Abstract：

Here we show that rapid ocean deoxygenation during OAE1a is linked to volcanic CO₂emissions and the crossing of an associated climate threshold, after which the sluggish pace of the silicate-weathering feedback and climate recovery delayed reoxygenation for >1 Myr. At the end of OAE1a, recrossing this threshold allowed for ocean reoxygenation. Following OAE1a, however, the Earth system remained sufficiently warm such that orbitally forced climate dynamics led to continued cyclic ocean deoxygenation on approximately 100-kyr timescales for another 1 Myr. Our results thus imply a tight coupling between volcanism, weathering and ocean oxygen content that is characterized by a climate threshold.