55 research outputs found

    Synthesis and Properties of a Dicationic π‑Extended Dithieno[3,2‑<i>c</i>:2′,3′‑<i>e</i>]‑2,7-diketophosphepin

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    Methylation of the triazole units of a π-extended, fluorescent dithieno­[3,2-<i>c</i>:2′,3′-<i>e</i>]-2,7-diketophosphepin gives rise to a N,N-dimethylated species that shows considerably blue-shifted absorption and emission wavelengths, as well as two reversible and remarkably low reduction steps at <i>E</i><sub>red</sub> = −1.12 and −1.39 V that underline its improved electron-acceptor features. The observed properties are the result of considerably altered electronic as well as structural features triggered by simple methylation of the scaffold

    Morphology of <i>in vitro</i> fertilized (IVF) deer mice oocytes at various stages of development <i>in vitro</i>.

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    <p>Typical phase contrast micrographs of developing embryos derived from IVF of MII oocytes retrieved from superovulation (A-C) and IVM (D-G). Fertilized oocytes with first and secondary polar bodies are clearly visible as indicated by arrows in panels (A) and (D), which was followed by the appearance of two pronuclei (one from oocytes before fertilization and one from sperm) as indicated by arrows in panels (B) and (E) and further development to 2-cell (C and F), and 4-cell (G) stages <i>in vitro</i>. Scale bar: 30 µm.</p

    Morphology of deer mice ovary aftersuperovulation treatment and cumulus-oocyte complexes (COC).

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    <p>(A) A typical deer mice ovary collected after superovulation treatment showing many antral follicles (arrows) containing COC in the ovarian cortex. (B) A typical COC isolated from antral follicles by follicular puncture. Scale bar: 500 and 80 µm in (A) and (B), respectively.</p

    Comparison of oocyte retrieval by superovulation from deer mice using different methods and hormone doses (the total number of animals n = 5 for each condition): GVBD, germinal vesicle breakdown; MII, metaphase II; hCG<b>, </b><b><i>human chorionic gonadotropin; and PMSG,</i></b> pregnant mare serum gonadotropin.

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    a<p>Percentage of MII oocytes out of total oocytes retrieved.</p>b<p>The 2-PMSG method includes a second administration of PMSG 24 h after the first one at the same dose, and hCG at the same dose was applied 48 h after the 2<sup>nd</sup> PMSG administration. Oocytes were isolated from the oviduct 18 h after hCG.</p>c<p>The 1-PMSG method consist one PMSG administration at the given dose and hCG at the same dose was applied 56 h later. Oocytes were isolated from the oviduct 15 h after hCG administration.</p

    Development of embryos derived from IVF (<i>in vitro</i> fertilization) of metaphase II (MII) deer mice oocytes obtained by superovulation vs. IVM (<i>in vitro</i> maturation): The total number of animals used n = 23.

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    a<p>Fertilized oocytes were judged by the appearance of secondary polar body as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0056158#pone-0056158-g003" target="_blank">Fig. 3A and D</a>.</p>b<p>Percentage of fertilized oocytes.</p>c<p>A total of 15 fertilized oocytes was monitored for the formation of two pronuclei.</p

    Morphology of deer mice oocytes isolated by superovulation and <i>in vitro</i> maturation (IVM).

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    <p>Typical phase contrast micrographs of oocytes derived by superovulation (A) and IVM (B, 19 h maturation) of antral follicles from deer mice hormone-primed using 5 IU PMSG and hCG using the 1-PMSG method. The first polar bodies are observable in MII oocytes in both panels. Scale bars: 70 µm.</p

    Quantification of PIF in HeLa cells during freezing.

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    <p>(A) calculated normalized cell volume of HeLa cells during freezing using model parameters determined from the water transport studies where arrows indicate the starting points of the critical volumes <i>V<sub>f</sub><sup>XCN</sup></i>, (B) probability of ice formation in HeLa cells appeared as darkening (square), twitching (triangle), and both (circle) at cooling rates together with model fit assuming SCN only (dotted line) and both SCN and VCN (solid line), and (C) the dependence on cooling rate of maximum PIF appeared as darkening (square), twitching (triangle), and both (circle) in HeLa cells.</p

    An Improved Model for Nucleation-Limited Ice Formation in Living Cells during Freezing

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    <div><p>Ice formation in living cells is a lethal event during freezing and its characterization is important to the development of optimal protocols for not only cryopreservation but also cryotherapy applications. Although the model for probability of ice formation (PIF) in cells developed by Toner et al. has been widely used to predict nucleation-limited intracellular ice formation (IIF), our data of freezing Hela cells suggest that this model could give misleading prediction of PIF when the maximum PIF in cells during freezing is less than 1 (PIF ranges from 0 to 1). We introduce a new model to overcome this problem by incorporating a critical cell volume to modify the Toner's original model. We further reveal that this critical cell volume is dependent on the mechanisms of ice nucleation in cells during freezing, <i>i.e.</i>, surface-catalyzed nucleation (SCN) and volume-catalyzed nucleation (VCN). Taken together, the improved PIF model may be valuable for better understanding of the mechanisms of ice nucleation in cells during freezing and more accurate prediction of PIF for cryopreservation and cryotherapy applications.</p></div

    The cryomicroscopy system used for experimental studies.

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    <p>(A) an overview of the whole setup including the computer, Olympus BX53 microscope, CCD camera, and FDCS196 cryostage assembly, (B) a close-up view of the cryostage assembly, and (C) an inside view of the silver cryostage for cooling/warming together with the copper wire for seeding extracellular ice.</p
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