Diabetes-Related Ankyrin Repeat Protein (DARP/Ankrd23) Modifies Glucose Homeostasis by Modulating AMPK Activity in Skeletal Muscle.

Skeletal muscle is the major site for glucose disposal, the impairment of which closely associates with the glucose intolerance in diabetic patients. Diabetes-related ankyrin repeat protein (DARP/Ankrd23) is a member of muscle ankyrin repeat proteins, whose expression is enhanced in the skeletal muscle under diabetic conditions; however, its role in energy metabolism remains poorly understood. Here we report a novel role of DARP in the regulation of glucose homeostasis through modulating AMP-activated protein kinase (AMPK) activity. DARP is highly preferentially expressed in skeletal muscle, and its expression was substantially upregulated during myotube differentiation of C2C12 myoblasts. Interestingly, DARP-/- mice demonstrated better glucose tolerance despite similar body weight, while their insulin sensitivity did not differ from that in wildtype mice. We found that phosphorylation of AMPK, which mediates insulin-independent glucose uptake, in skeletal muscle was significantly enhanced in DARP-/- mice compared to that in wildtype mice. Gene silencing of DARP in C2C12 myotubes enhanced AMPK phosphorylation, whereas overexpression of DARP in C2C12 myoblasts reduced it. Moreover, DARP-silencing increased glucose uptake and oxidation in myotubes, which was abrogated by the treatment with AICAR, an AMPK activator. Of note, improved glucose tolerance in DARP-/- mice was abolished when mice were treated with AICAR. Mechanistically, gene silencing of DARP enhanced protein expression of LKB1 that is a major upstream kinase for AMPK in myotubes in vitro and the skeletal muscle in vivo. Together with the altered expression under diabetic conditions, our data strongly suggest that DARP plays an important role in the regulation of glucose homeostasis under physiological and pathological conditions, and thus DARP is a new therapeutic target for the treatment of diabetes mellitus

Chemical characteristics in a 22-m ice core on the Belukha Glacier, Russia

To better understand how the chemical composition of a glacier in an inland continental region relates to the local climate, we collected ice core samples from the Belukha Glacier, Russia, in July 2001. We analyzed the samples for pH, anions, and cations. The primary soluble ions were SO42-, NO3-, NH4+, Ca2+, and HCOO-. Moreover, we argue the following. 1) Ca2+ and its equivalent SO42-+ NO3- likely originated from terrestrial dust such as soil. 2) HCOO- and its equivalent NH4+ likely originated from vegetation and/or biomass burning. 3) The remaining SO42-+NO3- and NH4+ likely originated from livestock, commercial fertilizers, and natural fertilizers. 4) The NH4+ concentration was low when there was no contribution from vegetation and/or biomass burning

Satellite-derived snow grain size over the Greenland Ice Sheet and its relationships with climate indices

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / 2F Auditorium, National Institute of Polar Researc

Amorphous Aluminosilicate Nanosheets as Universal Precursors for the Synthesis of Diverse Zeolite Nanosheets for Polymer‐Cracking Reactions

Zeolites catalyze some reactions in their molecular-sized pores, but large molecules can react only on their external surface. Zeolite-nanosheets (NSs) have been developed as catalysts for large molecules. The previously reported methods to synthesize zeolite-NSs are specialized for each zeolite type. Here we propose a new method to synthesize various zeolite-NSs from the same amorphous aluminosilicate NSs (AAS-NSs) as a universal precursor. We successfully synthesized the unprecedented AAS-NSs in the hydrophilic space of the stable hyperswollen lyotropic lamellar (HL) phase. The four zeolite types could be obtained from the single-species AAS-NSs. These results imply that this method enables us to synthesize almost all types of zeolite-NSs. Moreover, the synthesized CHA-NSs have great potential for various applications because of their thickness and large external surface area.Sasaki Koki, Gaitan Jose A. Hernandez, Okue Tsuyoshi, et al. Amorphous Aluminosilicate Nanosheets as Universal Precursors for the Synthesis of Diverse Zeolite Nanosheets for Polymer‐Cracking Reactions. Angewandte Chemie 134, (2022); https://doi.org/10.1002/ange.202213773

Isotopic evidence for acidity-driven enhancement of sulfate formation after SO2 emission control

After the 1980s, atmospheric sulfate reduction is slower than the dramatic reductions in sulfur dioxide (SO2) emissions. However, a lack of observational evidence has hindered the identification of causal feedback mechanisms. Here, we report an increase in the oxygen isotopic composition of sulfate (Δ17OSO42-) in a Greenland ice core, implying an enhanced role of acidity-dependent in-cloud oxidation by ozone (up to 17 to 27 in sulfate production since the 1960s. A global chemical transport model reproduces the magnitude of the increase in observed Δ17OSO42- with a 10 to 15 to sulfate in Eastern North America and Western Europe. With an expected continued decrease in atmospheric acidity, this feedback will continue in the future and partially hinder air quality improvements

グリーンランド北西氷床（SIGMA-D）アイスコアを用いた過去157年間の気候復元

第6回極域科学シンポジウム[OM] 極域気水圏11月16日（月）　統計数理研究所 セミナー室2（D304

Increased oceanic dimethyl sulfide emissions in areas of sea ice retreat inferred from a Greenland ice core

Summer sea ice retreat in the high latitude North Atlantic since 2000 is associated with increases in oceanic emissions of dimethyl sulfide, according to a record of methane sulfonic acid fluxes from an ice core in southeast Greenland