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Pantropical climate interactions
Cai, Wenju,Wu, Lixin,Lengaigne, Matthieu,Li, Tim,McGregor, Shayne,Kug, Jong-Seong,Yu, Jin-Yi,Stuecker, Malte F.,Santoso, Agus,Li, Xichen,Ham, Yoo-Geun,Chikamoto, Yoshimitsu,Ng, Benjamin,McPhaden, Mich American Association for the Advancement of Scienc 2019 Science Vol.363 No.6430
<P><B>Tropical interconnections</B></P><P>The El Niño–Southern Oscillation, which originates in the tropical Pacific, affects the rest of the world's tropics by perturbing global atmospheric circulation. Less appreciated than this influence is how the tropical Atlantic and Indian Oceans affect the Pacific. Cai <I>et al.</I> review what we know about these pantropical interactions, discuss possible ways of improving predictions of current climate variability, and consider how projecting future climate under different anthropogenic forcing scenarios may be improved. They argue that making progress in this field will require sustained global climate observations, climate model improvements, and theoretical advances.</P><P><I>Science</I>, this issue p. eaav4236</P><P>The El Niño–Southern Oscillation (ENSO), which originates in the Pacific, is the strongest and most well-known mode of tropical climate variability. Its reach is global, and it can force climate variations of the tropical Atlantic and Indian Oceans by perturbing the global atmospheric circulation. Less appreciated is how the tropical Atlantic and Indian Oceans affect the Pacific. Especially noteworthy is the multidecadal Atlantic warming that began in the late 1990s, because recent research suggests that it has influenced Indo-Pacific climate, the character of the ENSO cycle, and the hiatus in global surface warming. Discovery of these pantropical interactions provides a pathway forward for improving predictions of climate variability in the current climate and for refining projections of future climate under different anthropogenic forcing scenarios.</P>
Seasonal to multiannual marine ecosystem prediction with a global Earth system model
Park, Jong-Yeon,Stock, Charles A.,Dunne, John P.,Yang, Xiaosong,Rosati, Anthony American Association for the Advancement of Scienc 2019 Science Vol.365 No.6450
<P><B>Predicting marine futures</B></P><P>The ability to predict how climate variations will affect marine ecosystems would allow better economic and ecosystem planning and management. Park <I>et al.</I> found that a global Earth system model skillfully predicted seasonal to multiannual ocean chlorophyll fluctuations in many regions. This could allow annual fish catches in some regions to be forecast 2 to 3 years in advance.</P><P><I>Science</I>, this issue p. 284</P><P>Climate variations have a profound impact on marine ecosystems and the communities that depend upon them. Anticipating ecosystem shifts using global Earth system models (ESMs) could enable communities to adapt to climate fluctuations and contribute to long-term ecosystem resilience. We show that newly developed ESM-based marine biogeochemical predictions can skillfully predict satellite-derived seasonal to multiannual chlorophyll fluctuations in many regions. Prediction skill arises primarily from successfully simulating the chlorophyll response to the El Niño–Southern Oscillation and capturing the winter reemergence of subsurface nutrient anomalies in the extratropics, which subsequently affect spring and summer chlorophyll concentrations. Further investigations suggest that interannual fish-catch variations in selected large marine ecosystems can be anticipated from predicted chlorophyll and sea surface temperature anomalies. This result, together with high predictability for other marine-resource–relevant biogeochemical properties (e.g., oxygen, primary production), suggests a role for ESM-based marine biogeochemical predictions in dynamic marine resource management efforts.</P>
Turbulence and Magnetic Fields in the Large-Scale Structure of the Universe
Ryu, D.,Kang, H.,Cho, J.,Das, S. American Association for the Advancement of Scienc 2008 Science Vol.320 No.5878
<P>The nature and origin of turbulence and magnetic fields in the intergalactic space are important problems that are yet to be understood. We propose a scenario in which turbulent-flow motions are induced via the cascade of the vorticity generated at cosmological shocks during the formation of the large-scale structure. The turbulence in turn amplifies weak seed magnetic fields of any origin. Supercomputer simulations show that the turbulence is subsonic inside clusters and groups of galaxies, whereas it is transonic or mildly supersonic in filaments. Based on a turbulence dynamo model, we then estimated that the average magnetic field strength would be a few microgauss (microG) inside clusters and groups, approximately 0.1 muG around clusters and groups, and approximately 10 nanogauss in filaments. Our model presents a physical mechanism that transfers the gravitational energy to the turbulence and magnetic field energies in the large-scale structure of the universe.</P>
PA-824 Kills Nonreplicating Mycobacterium tuberculosis by Intracellular NO Release
Singh, R.,Manjunatha, U.,Boshoff, H. I. M.,Ha, Y. H.,Niyomrattanakit, P.,Ledwidge, R.,Dowd, C. S.,Lee, I. Y.,Kim, P.,Zhang, L.,Kang, S.,Keller, T. H.,Jiricek, J.,Barry, C. E. American Association for the Advancement of Scienc 2008 Science Vol.322 No.5906
<P>Bicyclic nitroimidazoles, including PA-824, are exciting candidates for the treatment of tuberculosis. These prodrugs require intracellular activation for their biological function. We found that Rv3547 is a deazaflavin-dependent nitroreductase (Ddn) that converts PA-824 into three primary metabolites; the major one is the corresponding des-nitroimidazole (des-nitro). When derivatives of PA-824 were used, the amount of des-nitro metabolite formed was highly correlated with anaerobic killing of Mycobacterium tuberculosis (Mtb). Des-nitro metabolite formation generated reactive nitrogen species, including nitric oxide (NO), which are the major effectors of the anaerobic activity of these compounds. Furthermore, NO scavengers protected the bacilli from the lethal effects of the drug. Thus, these compounds may act as intracellular NO donors and could augment a killing mechanism intrinsic to the innate immune system.</P>
Rewiring of Genetic Networks in Response to DNA Damage
Bandyopadhyay, S.,Mehta, M.,Kuo, D.,Sung, M.-K.,Chuang, R.,Jaehnig, E. J.,Bodenmiller, B.,Licon, K.,Copeland, W.,Shales, M.,Fiedler, D.,Dutkowski, J.,Guenole, A.,van Attikum, H.,Shokat, K. M.,Kolodner American Association for the Advancement of Scienc 2010 Science Vol.330 No.6009
<P>Although cellular behaviors are dynamic, the networks that govern these behaviors have been mapped primarily as static snapshots. Using an approach called differential epistasis mapping, we have discovered widespread changes in genetic interaction among yeast kinases, phosphatases, and transcription factors as the cell responds to DNA damage. Differential interactions uncover many gene functions that go undetected in static conditions. They are very effective at identifying DNA repair pathways, highlighting new damage-dependent roles for the Slt2 kinase, Pph3 phosphatase, and histone variant Htz1. The data also reveal that protein complexes are generally stable in response to perturbation, but the functional relations between these complexes are substantially reorganized. Differential networks chart a new type of genetic landscape that is invaluable for mapping cellular responses to stimuli.</P>