312 research outputs found

    Fabrication of Molecular Devices

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    This project focuses on the synthesis and attachment of metal nanoparticles to Au and GaAs surfaces using a combination of chemical self-assembly and scanned probe lithography. In this project self-assembled monolayers (SAMs) of alkanethiols and dithiols were prepared on Au and GaAs surfaces. There chemical assembly was investigated using a combination of Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The surface morphology and nanopatterning of these SAMs was investigated using atomic force microscopy. Lastly, as the final goal of the project was to create single electron tunneling devices by attaching metal nanoparticles to these surfaces, Au nanoparticles of varying sizes ranging from ca 2 ā€“ 12 nm were synthesized

    Identification, Isolation, and Characterization of Developmental Toxins from the Cyanobacterium Fischerella 52-1 Using the Zebrafish (Danio rerio) Embryo Model

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    Cyanobacteria, also known as blue-green algae, are known to produce a number of biologically active compounds. Extracts of cultured cyanobacteria isolated from South Florida sources were screened for possible developmental toxins using the zebrafish (Danio rerio) embryo as a model of vertebrate development. A strain of cyanobacteria, Fischerella 52-1, isolated from the Florida Everglades, was found to produce metabolites that caused a consistent developmental dysfunction in embryos exposed to lipophilic extract. Initial chemical characterization of the bioactive fraction identified a series of eight apparent indole-containing compounds. The two main components were purified using the zebrafish embryo model to guide the fractionation. Chemical characterization using 1- and 2-dimensional NMR, HESIMS, HRHESIMS, and IR determined that the two main compounds were the previously identified 12-epi-Hapalindole H Isonitrile, and a novel compound 12-epi-Ambiugine B Nitrile. The major contributor of the developmental defects detected in the zebrafish embryos was 12-epi-Hapalindole H Isonitrile

    Conditional deletion of the bcl-x gene from mouse mammary epithelium results in accelerated apoptosis during involution but does not compromise cell function during lactation

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    In the mammary gland Bcl-x is the most abundant cell survival factor from the Bcl-2 family. Since Bcl-x null mice die around day 12 of embryogenesis, the relevance of this protein in organ development and function is poorly understood. In erythroid cells bcl-x gene expression is controlled by cytokines and the transcription factor Stat5 (signal transducer and activator of transcription). However, we identified that bcl-x RNA levels in mammary tissue from prolactin receptor- and Stat5-null mice were indistinguishable from wild type mice. We have proposed that Bcl-x might control the survival of mammary epithelial cells throughout pregnancy, lactation, and the early stages of involution, and we have now tested this hypothesis through the conditional deletion of the bcl-x gene from mouse mammary epithelium. Conditional (floxed) bcl-x alleles were excised from alveolar cells during pregnancy using a Cre transgene under the control of the whey acidic protein gene promoter. Deletion of the bcl-x gene from the entire epithelial compartment (ducts and alveoli) was achieved by expressing Cre-recombinase under control of the mouse mammary tumor virus long terminal repeat. The absence of Bcl-x did not compromise proliferation and differentiation of mammary ductal and alveolar epithelial cells in virgin mice and during pregnancy and lactation. However, epithelial cell death and tissue remodeling were accelerated in the bcl-x conditional knockout mice during the first stage of involution. Concomitant deletion of the bax gene did not significantly modify the Bcl-x phenotype. Our results suggest that Bcl-x is not essential during mammopoiesis, but is critical for controlled apoptosis during the first phase of involution. Published by Elsevier Science Ireland Ltd

    A YY1-dependent increase in aerobic metabolism is indispensable for intestinal organogenesis

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    During late gestation, villi extend into the intestinal lumen to dramatically increase the surface area of the intestinal epithelium, preparing the gut for the neonatal diet. Incomplete development of the intestine is the most common gastrointestinal complication in neonates, but the causes are unclear. We provide evidence in mice that Yin Yang 1 (Yy1) is crucial for intestinal villus development. YY1 loss in the developing endoderm had no apparent consequences until late gestation, after which the intestine differentiated poorly and exhibited severely stunted villi. Transcriptome analysis revealed that YY1 is required for mitochondrial gene expression, and ultrastructural analysis confirmed compromised mitochondrial integrity in the mutant intestine. We found increased oxidative phosphorylation gene expression at the onset of villus elongation, suggesting that aerobic respiration might function as a regulator of villus growth. Mitochondrial inhibitors blocked villus growth in a fashion similar to Yy1 loss, thus further linking oxidative phosphorylation with late-gestation intestinal development. Interestingly, we find that necrotizing enterocolitis patients also exhibit decreased expression of oxidative phosphorylation genes. Our study highlights the still unappreciated role of metabolic regulation during organogenesis, and suggests that it might contribute to neonatal gastrointestinal disorders

    WNT5a in Tongue and Fungiform Papilla Development

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71558/1/j.1749-6632.2009.04369.x.pd
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