Elucidation of the liquid-liquid distribution behavior of ion associates of metal-halogeno complex anions with quaternary ammonium counter cations and its application to separation and analysis

第四級アンモニウムイオンを対イオンとする一価, 二価金属ハロゲノ錯陰イオンのイオン会合抽出挙動を把握し, 分離・分析的応用を図るために, 炭素数及び形状の異なる第四級アンモニウム陽イオンを用いて, 水-各種抽出溶媒 {1,2-ジクロロエタン, クロロホルム (CF), クロロベンゼン (Cl-B), ベンゼン (B), トルエン (T) 及び四塩化炭素 (CTC)} 系での抽出定数を求めた. 得られた抽出定数から次の知見を得た. (1) 配位子の抽出性に及ぼす影響 : 配位子がCl-, Br-, I-と変わるにつれ, この順に抽出性は良くなる. (2) 配位子数の影響 : 配位子数が多くなるに従い, 抽出性も良くなる. (3) 中心金属の影響 : 配位子数が同じ場合には, 抽出性はほぼ中心金属イオンの大きさの順となる. (4) 金属錯陰イオンの電荷の影響 : 一般に二価陰イオンよりも一価陰イオンのほうが抽出されやすい. (5) 対陽イオンのアルキル鎖のメチレン基の寄与 : メチレン基一つ当たり, 大体0.4～0.8の抽出定数 (log K(ex)) の増大となる. (6) 抽出溶媒の影響 : 抽出溶媒の抽出能は次の順となる : CTC<T<B<Cl-B<CF. (7) 金属ハロゲノ錯陰イオンの配位子の違いによる抽出定数の差 (Δlog K(ex)) は溶媒によらず, ほぼ一定である. これらの知見を基に, 金属ハロゲノ錯陰イオンと疎水性陽イオンとのイオン会合抽出を利用する幾つかの金属の分離・定量法を開発した.The distribution behavior of ion associates of both monovalent and divalent metal-halogeno complex anions with various quaternary ammonium cations between the aqueous phase and several organic phases {1,2-dichloroethane, chloroform (CF), chlorobenzene (Cl-B), benzene (B), toluene (T) and carbon tetrachloride (CTC)} was examined, and the extraction constants (log Kex) were determined. The larger is the size of the ligand (Cl-<Br-<I-) and the coordination number, the greater is the ion associability. For the same coordination number, in general, the larger is the size of the metal ion, the greater is the ion associability. In general, the extractability of monovalent metal-halogeno complex anions is larger than that of divalent metal-halogeno complex anions. A linear relationship was obtained between log Kex and the number of carbon atoms in quaternary ammonium ion, and the contribution of a methylene group to the extraction constant (Δlog K(ex)/-CH(2-)) was found to be about 0.4∼0.8. Among the ion associates examined, the order of the extractability of the extracting solvent was generally CTC<T<B<Cl-B<CF. Also, the order of the extractability of the ion associates for dihalogenocuprate (I), tetrahalogenoaurate (III) and tetrahalogenothallate (III) complex ions was as follows, respectively : CuCl(2)-<CuBr(2)-<CuI(2)- ; AuCl(4)-<AuBr(4)- ; TlCl(4)-<TlBr(4)-<TlI(4-). The values of Δlog K(ex) between the complex anions were almost equal, even though the extracting solvents were changed. From these results, several extraction-spectrophotometric methods for the determination of metal based on the formation of an ion associate of metal-halogeno complex anion with hydrophobic cations were developed

Role of the RNA-Binding Protein Nrd1 in Stress Granule Formation and Its Implication in the Stress Response in Fission Yeast

We have previously identified the RNA recognition motif (RRM)-type RNA-binding protein Nrd1 as an important regulator of the posttranscriptional expression of myosin in fission yeast. Pmk1 MAPK-dependent phosphorylation negatively regulates the RNA-binding activity of Nrd1. Here, we report the role of Nrd1 in stress-induced RNA granules. Nrd1 can localize to poly(A)-binding protein (Pabp)-positive RNA granules in response to various stress stimuli, including heat shock, arsenite treatment, and oxidative stress. Interestingly, compared with the unphosphorylatable Nrd1, Nrd1DD (phosphorylation-mimic version of Nrd1) translocates more quickly from the cytoplasm to the stress granules in response to various stimuli; this suggests that the phosphorylation of Nrd1 by MAPK enhances its localization to stress-induced cytoplasmic granules. Nrd1 binds to Cpc2 (fission yeast RACK) in a phosphorylation-dependent manner and deletion of Cpc2 affects the formation of Nrd1-positive granules upon arsenite treatment. Moreover, the depletion of Nrd1 leads to a delay in Pabp-positive RNA granule formation, and overexpression of Nrd1 results in an increased size and number of Pabp-positive granules. Interestingly, Nrd1 deletion induced resistance to sustained stresses and enhanced sensitivity to transient stresses. In conclusion, our results indicate that Nrd1 plays a role in stress-induced granule formation, which affects stress resistance in fission yeast

Distinct functions of HTLV-1 Tax1 from HTLV-2 Tax2 contribute key roles to viral pathogenesis

While the human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia/lymphoma (ATL), to date, its close relative HTLV-2 is not associated with ATL or other types of malignancies. Accumulating evidence shows that HTLV-1 Tax1 and HTLV-2 Tax2 have many shared activities, but the two proteins have a limited number of significantly distinct activities, and these distinctions appear to play key roles in HTLV-1 specific pathogenesis. In this review, we summarize the functions of Tax1 associated with cell survival, cell proliferation, persistent infection as well as pathogenesis. We emphasize special attention to distinctions between Tax1 and Tax2

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Mammalian Rcd1 is a novel transcriptional cofactor that mediates retinoic acid-induced cell differentiation

Rcd1, initially identified as a factor essential for the commitment to nitrogen starvation-invoked differentiation in fission yeast, is one of the most conserved proteins found across eukaryotes, and its mammalian homolog is expressed in a variety of differentiating tissues. Here we show that mammalian Rcd1 is a novel transcriptional cofactor and is critically involved in the commitment step in the retinoic acid-induced differentiation of F9 mouse teratocarcinoma cells, at least in part, via forming complexes with retinoic acid receptor and activation transcription factor-2 (ATF-2). In addition, antisense oligonucleotide treatment of embryonic mouse lung explants suggests that Rcd1 also plays a role in retinoic acid-controlled lung development