The intricate currents of the Northwest Pacific Ocean, with strong manifestations along the westside rim, connect tropical and subtropical gyres and significantly influence East Asian and global climates. The El Niño/Southern Oscillation (ENSO) originates in the tropical Pacific Ocean and disrupts this ocean circulation system. However, the spatiotemporal dependence of the impact of ENSO events has yet to be elucidated because of the complexities of both ENSO events and circulation systems, as well as the increased availability of observational data. We thus combined altimeter and drifter observations to demonstrate the distinct tropical and subtropical influences of the circulation system on ENSO diversity. During El Niño years, the North Equatorial Current, North Equatorial Countercurrent, Mindanao Current, Indonesian Throughflow, and the subtropical Kuroshio Current and its Extension region exhibit strengthening, while the tropical Kuroshio Current weakens. The tropical impact is characterized by sea level changes in the warm pool, whereas the subtropical influence is driven by variations in the wind stress curl. The tropical and subtropical influences are amplified during the Centra Pacific El Niño years compared to the Eastern Pacific El Niño years. As the globe warms, these impacts are anticipated to intensify. Thus, strengthening observation systems and refining climate models are essential for understanding and projecting the enhancing influences of ENSO on the Northwest Pacific Oceanic circulation.
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Protein farnesylation is a post-translational modification where a 15-carbon farnesyl isoprenoid is appended to the C-terminal end of a protein by farnesyltransferase (FTase). This process often causes proteins to associate with the membrane and participate in signal transduction pathways. The most common substrates of FTase are proteins that have C-terminal tetrapeptide CaaX box sequences where the cysteine is the site of modification. However, recent work has shown that five amino acid sequences can also be recognized, including the pentapeptides CMIIM and CSLMQ. In this work, peptide libraries were initially used to systematically vary the residues in those two parental sequences using an assay based on Matrix Assisted Laser Desorption Ionization–Mass Spectrometry (MALDI-MS). In addition, 192 pentapeptide sequences from the human proteome were screened using that assay to discover additional extended CaaaX-box motifs. Selected hits from that screening effort were rescreened using an in vivo yeast reporter protein assay. The X-ray crystal structure of CMIIM bound to FTase was also solved, showing that the C-terminal tripeptide of that sequence interacted with the enzyme in a similar manner as the C-terminal tripeptide of CVVM, suggesting that the tripeptide comprises a common structural element for substrate recognition in both tetrapeptide and pentapeptide sequences. Molecular dynamics simulation of CMIIM bound to FTase further shed light on the molecular interactions involved, showing that a putative catalytically competent Zn(II)-thiolate species was able to form. Bioinformatic predictions of tetrapeptide (CaaX-box) reactivity correlated well with the reactivity of pentapeptides obtained from in vivo analysis, reinforcing the importance of the C-terminal tripeptide motif. This analysis provides a structural framework for understanding the reactivity of extended CaaaX-box motifs and a method that may be useful for predicting the reactivity of additional FTase substrates bearing CaaaX-box sequences.
Free, publicly-accessible full text available May 1, 2025 -
Cation‐disordered rock salts (DRXs) are well known for their potential to realize the goal of achieving scalable Ni‐ and Co‐free high‐energy‐density Li‐ion batteries. Unlike in most cathode materials, the disordered cation distribution may lead to more factors that control the electrochemistry of DRXs. An important variable that is not emphasized by research community is regarding whether a DRX exists in a more thermodynamically stable form or a more metastable form. Moreover, within the scope of metastable DRXs, over‐stoichiometric DRXs, which allow relaxation of the site balance constraint of a rock salt structure, are particularly underexplored. In this work, these findings are reported in locating a generally applicable approach to “metastabilize” thermodynamically stable Mn‐based DRXs to metastable ones by introducing Li over‐stoichiometry. The over‐stoichiometric metastabilization greatly stimulates more redox activities, enables better reversibility of Li deintercalation/intercalation, and changes the energy storage mechanism. The metastabilized DRXs can be transformed back to the thermodynamically stable form, which also reverts the electrochemical properties, further contrasting the two categories of DRXs. This work enriches the structural and compositional space of DRX families and adds new pathways for rationally tuning the properties of DRX cathodes.more » « lessFree, publicly-accessible full text available December 1, 2024
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Abstract The wind-driven meridional overturning circulation between the tropical and subtropical oceans is important for regulating decadal-scale temperature fluctuations in the Pacific Ocean and globally. An acceleration of the overturning circulation can act to reduce global surface temperature as ocean stores more heat. The equatorward low-latitude western boundary current represents a key component of the meridional circulation cell in the Pacific and a major source of water mass for the Equatorial Undercurrent, yet long-term observations of its transport are scarce. Here we demonstrate that the15N/14N ratio recorded by
Porites spp. corals in the western tropical South Pacific is sensitive to the exchanges of water masses driven by the western boundary transport. Using a 94-year coral record from the Solomon Sea, we report that the15N/14N ratio declined as the global surface temperature rose. The record suggests that the South Pacific western boundary current has strengthened in the past century, and it may have contributed to the reported strengthening of the Equatorial Undercurrent. In addition, the15N/14N record shows strong decadal variability, indicative of weaker equatorial Pacific upwelling and stronger western boundary transport when the eastern equatorial Pacific is in the warm stage of the Pacific Decadal Oscillation. -
Abstract Developing low‐voltage carboxylate anode materials is critical for achieving low‐cost, high‐performance, and sustainable Na‐ion batteries (NIBs). However, the structure design rationale and structure‐performance correlation for organic carboxylates in NIBs remains elusive. Herein, the spatial effect on the performance of carboxylate anode materials is studied by introducing heteroatoms in the conjugation structure and manipulating the positions of carboxylate groups in the aromatic rings. Planar and twisted organic carboxylates are designed and synthesized to gain insight into the impact of geometric structures to the electrochemical performance of carboxylate anodes in NIBs. Among the carboxylates, disodium 2,2’‐bipyridine‐5,5’‐dicarboxylate (2255‐Na) with a planar structure outperforms the others in terms of highest specific capacity (210 mAh g−1), longest cycle life (2000 cycles), and best rate capability (up to 5 A g−1). The cyclic stability and redox mechanism of 2255‐Na in NIBs are exploited by various characterization techniques. Moreover, high‐temperature (up to 100 °C) and all‐organic batteries based on a 2255‐Na anode, a polyaniline (PANI) cathode, and an ether‐based electrolyte are achieved and exhibited exceptional electrochemical performance. Therefore, this work demonstrates that designing organic carboxylates with extended planar conjugation structures is an effective strategy to achieve high‐performance and sustainable NIBs.
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Abstract Introduction A large amount of literature has indicated that excitatory synaptic transmission plays a crucial role in epilepsy, but the detailed pathogenesis still needs to be clarified.
Methods In the present study, we used samples from patients with temporal lobe epilepsy, pentylenetetrazole‐kindled mice, and Mg2+‐free‐induced epileptic cultured hippocampal neurons to detect the expression pattern of STK24. Then, the whole‐cell recording was carried out after STK24 overexpression in the Mg2+‐free‐induced epileptic cultured hippocampal neurons. In addition, coimmunoprecipitation was performed to detect the association between endogenous STK24 and main subunits of NMDARs and AMPARs in the hippocampus of PTZ‐kindled mice.
Results Here, we reported that STK24 was specifically located in epileptic neurons of human and pentylenetetrazole‐kindled mice. Meanwhile, the expression of STK24 was significantly down‐regulated in these samples which are mentioned above. Besides, we found that the amplitude of miniature excitatory postsynaptic currents was increased in STK24 overexpressed epileptic hippocampal cultured neurons, which means the excitatory synaptic transmission was changed. Moreover, the coimmunoprecipitation, which further supported the previous experiment, indicated an association between STK24 and the subunits of the NMDA receptor.
Conclusion These findings expand our understanding of how STK24 involved in the excitatory synaptic transmission in epilepsy and lay a foundation for exploring the possibility of STK24 as a drug target.