37 research outputs found

    Maternal Genistein Alters Coat Color and Protects A(vy) Mouse Offspring from Obesity by Modifying the Fetal Epigenome

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    Genistein, the major phytoestrogen in soy, is linked to diminished female reproductive performance and to cancer chemoprevention and decreased adipose deposition. Dietary genistein may also play a role in the decreased incidence of cancer in Asians compared with Westerners, as well as increased cancer incidence in Asians immigrating to the United States. Here, we report that maternal dietary genistein supplementation of mice during gestation, at levels comparable with humans consuming high-soy diets, shifted the coat color of heterozygous viable yellow agouti (A(vy)/a) offspring toward pseudoagouti. This marked phenotypic change was significantly associated with increased methylation of six cytosine–guanine sites in a retrotransposon upstream of the transcription start site of the Agouti gene. The extent of this DNA methylation was similar in endodermal, mesodermal, and ectodermal tissues, indicating that genistein acts during early embryonic development. Moreover, this genistein-induced hypermethylation persisted into adulthood, decreasing ectopic Agouti expression and protecting offspring from obesity. Thus, we provide the first evidence that in utero dietary genistein affects gene expression and alters susceptibility to obesity in adulthood by permanently altering the epigenome

    Genes flanking Xist in mouse and human are separated on the X chromosome in American marsupials

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    X inactivation, the transcriptional silencing of one of the two X chromosomes in female mammals, achieves dosage compensation of X-linked genes relative to XY males. In eutherian mammals X inactivation is regulated by the X-inactive specific transcript (Xist), a cis-acting non-coding RNA that triggers silencing of the chromosome from which it is transcribed. Marsupial mammals also undergo X inactivation but the mechanism is relatively poorly understood. We set out to analyse the X chromosome in Monodelphis domestica and Didelphis virginiana, focusing on characterizing the interval defined by the Chic1 and Slc16a2 genes that in eutherians flank the Xist locus. The synteny of this region is retained on chicken chromosome 4 where other loci belonging to the evolutionarily ancient stratum of the human X chromosome, the so-called X conserved region (XCR), are also located. We show that in both M. domestica and D. virginiana an evolutionary breakpoint has separated the Chic1 and Slc16a2 loci. Detailed analysis of opossum genomic sequences revealed linkage of Chic1 with the Lnx3 gene, recently proposed to be the evolutionary precursor of Xist, and Fip1, the evolutionary precursor of Tsx, a gene located immediately downstream of Xist in eutherians. We discuss these findings in relation to the evolution of Xist and X inactivation in mammals

    Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy

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    Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications

    The Use of Iptycenes in Rational Macromolecular Design for Gas Separation Membrane Applications

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    Iptycene molecules, featuring three-dimensional [2,2,2]-ring configurations with 120° contortion sites and unique internal free volume (IFV) elements, have recently been identified for their great potential in the design of polymers for gas separation membranes. Some of these novel iptycene-containing polymers have already displayed unprecedented separation performance. This review summarizes the progression of the gas separation membranes, utilizing iptycene structures over the past five years by dividing the polymers into three categories: nonladder polymers, semiladder polymers, and ladder polymers. The focus lies on examining macromolecular design strategies of these novel polymers and consequential effects on chain packing, free volume architecture, and gas transport properties to provide useful guidance on the design of new membrane materials. Finally, we provide some perspectives and future research directions for designing and utilizing iptycene-containing polymers for gas separation membranes

    Structure Manipulation in Triptycene-Based Polyimides through Main Chain Geometry Variation and Its Effect on Gas Transport Properties

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    Two new triptycene-based polyimides, 6FDA-1,4-trip_<i>ortho</i> and 6FDA-2,6-trip_<i>para</i>, were synthesized to investigate the effect of varying polymer backbone geometry on chain packing and gas transport properties. Changing the imide linkage geometry from <i>para</i> to <i>ortho</i> reduced gas permeabilities by ∼48% due to more efficient chain packing of the asymmetric <i>ortho</i> structure, which is demonstrated by decreased <i>d</i>-spacing and fractional free volume. Varying the triptycene orientation from the 1,4- to 2,6-connection also caused a decrease in permeability (e.g., 29% decrease for <i>P</i><sub>CO2</sub>). This is likely the result of reduced chain mobility, as evidenced by increased <i>T</i><sub>g</sub>, and a shift in free volume distribution toward smaller cavities, as supported by smaller <i>d</i>-spacing. Physical aging studies show that the equilibrium specific volume of these isomeric polymers is similar, as evidenced by nearly identical gas transport properties exhibited by all aged samples