Yuko Hasegawa

Competition between a noncoding exon and introns: Gomafu contains tandem UACUAAC repeats and associates with splicing factor-1.

Gomafu (also referred to as RNCR2/MIAT) was originally identified as a noncoding RNA expressed in a particular set of neurons. Unlike protein‐coding mRNAs, the Gomafu RNA escapes nuclear export and stably accumulates in the nucleus, making a unique nuclear compartment. Although recent studies have revealed the functional relevance of Gomafu in a series of physiological processes, the underlying molecular mechanism remains largely uncharacterized. In this report, we identified a chicken homologue of Gomafu using a comparative genomic approach to search for functionally important and conserved sequence motifs among evolutionarily distant species. Unexpectedly, we found that all Gomafu RNA examined shared a distinctive feature: tandem repeats of UACUAAC, a sequence that has been identified as a conserved intron branch point in the yeast Saccharomyces cerevisiae. The tandem UACUAAC Gomafu RNA repeats bind to the SF1 splicing factor with a higher affinity than the divergent branch point sequence in mammals, which affects the kinetics of the splicing reaction in vitro. We propose that the Gomafu RNA regulates splicing efficiency by changing the local concentration of splicing factors within the nucleus.

Solvent extraction of 3B group metal ions from hydrochloric acid with trioctylphosphine oxide

Abstract The extraction of tervalent gallium, indium, and thallium has been studied with trioctylphosphine oxide (TOPO) in n-hexane from hydrochloric acid solutions in which the ionic concentration was kept at 4.0 mol dm−3 by replacing hydrogen ions with sodium ions. From the results it is concluded that the extracted species are GaCl3(TOPO)2, HGaCl4(TOPO)3 and also most probably H2GaCl5(TOPO)3 for Ga(III), InCl3 (TOPO)2 for In(III), and HTlCl4(TOPO)3 for Tl(III). The extraction constants were calculated as, Kex0,3 = [MCl3(TOPO)2]org[MCl3]−1 [TOPO]org−2 are >104.4 for Ga(III), 104.9 for In(III), and Kex1,4 = [HTlCl4(TOPO)3]org[H+]−1[Cl−]−1 × [TlCl3]−1[TOPO]org−3, is 109.7.

Solvent extraction of lead(II) and strontium(II) as dibenzo-18-crown-6 complexes with picrate ion

Abstract The solvent extraction of lead(II) and strontium(II) from aqueous lithium picrate solutions with dibenzo-18-crown-6 (DBC) in chloroform or benzene has been measured. From slope analysis, the extracted species are found to be Pb(DBC)(Pic)2 and Sr(DBC)(Pic)2. The distribution ratio of lead(II) is about forty to fifty times that of strontium(II). This is ascribed to the higher stability of the lead(II) DBC complex, and to weaker hydration of the lead(II) DBC complex. The extraction of both metals is stronger into a benzene than into a chloroform solution of DBC.

Selective separation of samarium(III) by synergistic extraction with β-diketone and methylphenylphenanthroline carboxamide.

Synergistic extraction of trivalent lanthanides (Lns(III)) with pivaloyltrifluoroacetone (HA) and N-methyl-N-phenyl-1,10-phenanthroline-2-carboxamide (MePhPTA) was evaluated across the Ln series. The distribution ratio (D) of Sm(III) under an identical condition was the largest among all Lns(III). The separation factor (SF) between Sm(III) and Nd(III) (SF=D(Sm)/D(Nd)) was 2.0 and SF between Sm(III) and Eu(III), (D(Sm)/D(Eu)) was 1.4. Upon analyzing the extraction data in detail on the basis of mass balance, it was found that the dominant extracted species of light Lns(III) was a stable ternary complex consisting of Ln(III), HA, and MePhPTA (B), namely, LnA(3)B, while the dominant extracted species of heavy Lns(III) was the ion pair, [LnA(2)B](+)ClO(4)(-). The complex for Pr(III) was very stable (the stability constant, β¯, denoted as [LnA(3)B](o)[LnA(3)](o)(-1)[B](o)(-1), was 10(8.3)). It suggests that LnA(3) can form two 5-membered rings with MePhPTA, and the size of Pr(III) matches to the distance between the donor atoms in MePhPTA. Although the stability constant decreased with increasing Ln atomic number, the synergistic extraction constant (K(ex31)=[LnA(3)B](o)[H(+)](3)[Ln(3+)](-1)[HA](o)(-3)[B](o)(-1)) was the largest for Sm(III). Since the constant, K(ex31,) is given by K(ex31)=K(ex30)×β¯ where K(ex30)=[LnA(3)](o)[H(+)](3)[Ln(3+)](-1)[HA](o)(-3), the largest K(ex31) of Sm(III) is attributable to the difference of the degree of the variation of K(ex30) between the light and the heavy Lns(III); the increment of extraction constant of LnA(3) (logK(ex30)) for light Lns is larger than the decrement of the stability constant of LnA(3)B (logβ¯), while the increment of logK(ex30) of post-Sm lessens than the decrement of logβ¯. From these results, it is concluded that selective separation of a particular Ln(III) among all Lns(III) is possible using synergistic extraction with a suitable combination of a multidentate β-diketone and a Lewis base.

Formation of nuclear bodies by the lncRNA Gomafu‐associating proteins Celf3 and SF1

Gomafu/MIAT/Rncr2 is a long noncoding RNA that has been proposed to control retinal cell specification, stem cell differentiation and alternative splicing of schizophrenia‐related genes. However, how Gomafu controls these biological processes at the molecular level has remained largely unknown. In this study, we identified the RNA‐binding protein Celf3 as a novel Gomafu‐associating protein. Knockdown of Celf3 led to the down‐regulation of Gomafu, and cross‐link RNA precipitation analysis confirmed specific binding between Celf3 and Gomafu. In the neuroblastoma cell line Neuro2A, Celf3 formed novel nuclear bodies (named CS bodies) that colocalized with SF1, another Gomafu‐binding protein. Gomafu, however, was not enriched in the CS bodies; instead, it formed distinct nuclear bodies in separate regions in the nucleus. These observations suggest that Gomafu indirectly modulates the function of the splicing factors SF1 and Celf3 by sequestering these proteins into separate nuclear bodies.

ION-PAIR EXTRACTION OF LANTHANOID(III) WITH CROWN ETHERS AND PICRATE ION

Abstract ABSTRACT The extraction of lanthanoid(III) with 15-crown-5, 18-crown-6, or dibenzo-18-crown-6, and picrate ions into chloroform was measured at 25°C. The stoichiometry of the dominant species extracted was found to be 1:2:3 with respect to lanthanbid(III), crown ether, and picrate ions. The extraction constants decrease through the lanthanoid series (except lanthanum). The constants for praseodymium or neodymium are larger than that for ytterbium or lutetium by an order of magnitude. The pattern of the plot of the extraction constants for the crown ethers vs. the lanthanoid atomic number is similar for all crown ethers tested, although the sizes of all the cations are close to the cavity size of 15C5. The present result suggests that lanthanoid(III) would not be trapped in the center of the cavity of the crown ether.

Xist Exon 7 Contributes to the Stable Localization of Xist RNA on the Inactive X-Chromosome

To equalize X-linked gene dosage between the sexes in mammalian females, Xist RNA inactivates one of the two X-chromosomes. Here, we report the crucial function of Xist exon 7 in X-inactivation. Xist exon 7 is the second-largest exon with a well-conserved repeat E in eutherian mammals, but its role is often overlooked in X-inactivation. Although female ES cells with a targeted truncation of the Xist exon 7 showed no significant differences in their Xist expression levels and RNA stability from control cells expressing wild-type Xist, compromised localization of Xist RNA and incomplete silencing of X-linked genes on the inactive X-chromosome (Xi) were observed in the exon 7-truncated mutant cells. Furthermore, the interaction between the mutant Xist RNA and hnRNP U required for localization of Xist RNA to the Xi was impaired in the Xist exon 7 truncation mutant cells. Our results suggest that exon 7 of Xist RNA plays an important role for stable Xist RNA localization and silencing of the X-linked genes on the Xi, possibly acting through an interaction with hnRNP U.

Synergistic extraction of lanthanoids(III) with 2-thenoyltrifluoroacetone and benzoic acid: thermodynamic parameters in the complexation in organic phases and the hydration.

In order to examine the reason why the magnitude of the synergistic effect observed in the extraction of lanthanoids(III) with a beta-diketone and a monodentate Lewis base generally decreases along with increasing atomic number, the hydration number of the extracted species when lanthanoids(III) are extracted with TTA (2-thenoyltrifluoroacetone, HA) and benzoic acid (HB) into chloroform by Karl Fischer titration and the enthalpy change in complexation between LnA(3) and HB by calorimetric titration were determined across the lanthanoid series at 25 degrees C. It has been concluded that since the decrement of entropy change caused by the change in the number of released water molecules and in the coordination number of lanthanoids(III) upon complexation is larger than the increment of the enthalpy change, the values of the second formation constants of the complexes decrease with increasing the atomic number across lanthanoid series so that the magnitude of the synergistic extraction decreases with increasing the atomic number.

Solvent extraction of europium(III) with crown ethers and picrate ions

The extraction of europium(III) with 15-crown-5 (15C5), benzo-15-crown-5 (B15C5), 18-crown-6 (18C6) or dibenzo-18-crown-6(DB18C6) and picrate anion into chloroform was measured at 25/sup 0/C. The stoichiometry in the species extracted was determined to be 1:2:3 with respect to europium(III), each crown ether employed and picrate ion. The extraction constants defined as K/sub ex/ = ((EuE/sub 2/A/sub 3/)/sub o//(Eu/sup 3 +/)/sub a/ x(E)/sub a//sup -2/ (A/sup -/)/sub a//sup -3/ were measured to be 10/sup 8.2/, 10/sup 11.1/, 10/sup 8.5/, and 10/sup 13.3/ for 15C5, B15C5, 18C6, and DB18C6, successively. 11 references, 2 figures, 1 table.

Dehydration from tris[β-diketonato]lanthanoids(III) on the 1,10-phenanthroline adduct formation across lanthanoid series

Abstract The residual hydration number of the metal ion in the 1,10-phenanthroline adducts of tris[1,1,1-trifluoro-5,5′-dimethyl-2,4-hexanedionato]lanthanoids in chloroform has been determined by coulometric Karl–Fischer titration and also by the luminescence lifetime of europium(III) in the complex. The residual hydration number was essentially zero for all lanthanoids across the series. This data and the hydration number of the lanthanoids(III) complexed with the β-diketone can be used to explain the trend of the variation of the formation constants of the adducts across the lanthanoid series.