NA 22598A1

The maintenance of ionic homeostasis in the cytoplasm is an essential and crucial physiological process for all living beings. At cellular level, Na+ concentrations are maintained by specialized Na+ transporting molecular machines, which operate in the cell or plasma membrane. In eukaryotes Na+ transporting P-type ATPase play an important role in Na+ homeostasis that is known as Na+/K+-ATPase in animal cells in which K+ acts as a counter ion for the exchange of sodium. Na+/K+-ATPase is not found in plants. In plants and fungi, proton gradients are maintained by plasma membrane H+-ATPase while in animal cells Na+ and K+ gradient is maintained by Na+/K+-ATPase. However, in case of algae, a few reports of Na+/K+-ATPase are available, that maintains optimum concentration gradients in the cytoplasm and is used by Na+/H+ antiporter to exchange of Na+ and H+ ions. The membrane potential derived as a result of ion gradients across the membrane is base for a variety of cellular processes. An active Na+ dependent cycle (P-type ATPase) is scarcely reported in algae as compared to marine bacteria/cyanobacteria and animals. The characterization of these transporter gene-encoding membrane transports in seaweed would contribute to the understanding of abiotic stress tolerance in these organisms. This review highlights the detailed account of algal along with animal type Na+-ATPase i.e. occurrence, properties, significance and their recent progress.

The influx of sodium (Na+ ) ions into a resting cell is regulated by Na+ channels and by Na+ /H+ and Na+ /Ca2+ exchangers, whereas Na+ ion efflux is mediated by the activity of Na+ /K+ -ATPase to maintain a high transmembrane Na+ ion gradient. Dysfunction of this system leads to changes in the intracellular sodium concentration that promotes cancer metastasis by mediating invasion and migration. In addition, the accumulation of extracellular Na+ ions in cancer due to inflammation contributes to tumor immunogenicity. Thus, alterations in the Na+ ion concentration may potentially be used as a biomarker for malignant tumor diagnosis and prognosis. However, current limitations in detection technology and a complex tumor microenvironment present significant challenges for the in vivo assessment of Na+ concentration in tumor. 23 Na-magnetic resonance imaging (23 Na-MRI) offers a unique opportunity to study the effects of Na+ ion concentration changes in cancer. Although challenged by a low signal-to-noise ratio, the development of ultrahigh magnetic field scanners and specialized sodium acquisition sequences has significantly advanced 23 Na-MRI. 23 Na-MRI provides biochemical information that reflects cell viability, structural integrity, and energy metabolism, and has been shown to reveal rapid treatment response at the molecular level before morphological changes occur. Here we review the basis of 23 Na-MRI technology and discuss its potential as a direct noninvasive in vivo diagnostic and prognostic biomarker for cancer therapy, particularly in cancer immunotherapy. We propose that 23 Na-MRI is a promising method with a wide range of applications in the tumor immuno-microenvironment research field and in cancer immunotherapy monitoring. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Na superionic conductor-structured phosphates have attracted wide interest due to their high working voltage and fast Na+ migration facilitated by the robust 3D open framework. However, they usually suffer from low-rate capability and inferior cycling stability due to the low intrinsic electronic conductivity and limited activated Na+ ions. Herein, a doping protocol with Na+ in the V3+ site is developed to activate extra electrochemical Na+ ions and expand the migration path of Na+, leading to the improvement of the electronic conductivity and diffusion kinetics. It is also disclosed that the generated stronger Na-O bonds with high ionicity significantly conduce to the enhanced structural stability in the Na+-substituted Na3.05V1.975Na0.025(PO4)3/C cathode. The obtained composite can deliver an excellent rate capacity of 83.8 mA h g-1 at 20 C and a moderate cycling persistence of 91.3% over 1500 cycles at 10 C with great fast-charging properties. The reversible structure evolution is confirmed by the ex situ XRD, XPS, and ICP characterization. This work sheds light on awakening electroactive Na+ ions and designing phosphates with superior electrochemical stability for practical Na-ion batteries.