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2000

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Linkage of a triple helix-forming oligonucleotide to amsacrine-4-carboxamide derivatives modulates the sequence-selectivity of topoisomerase II-mediated DNA cleavage

sAmsacrine-4-carboxamide-oligonucleotide conjugates were synthesized and studied for their capacity to form DNA triple helices and to after human topoisomerase II binding and cleavage properties. The intercalating agent was attached to the 3’- or the 5’-end of a 24 nt triple helix-forming oligonucleotide via linkers of different lengths. The stability of these DNA triple helices was investigated by gel retardation and melting temperature studies using a synthetic 70 bp DNA duplex target. The effect of the conjugates on DNA cleavage by topoisomerase II was evaluated using the 70 bp duplex and a 311 bp restriction fragment containing the same triple helix site. The conjugate with the amsacrine derivative linked to the 3’ end of the TFO via a hexaethylene glycol linker modulates the extent of DNA cleavage by topoisomerase II at specific sites.

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Marek’s disease virus (MDV) homologues of herpes simplex virus type 1 UL49 (VP22) and UL48 (VP16) genes : high-level expression and characterization of MDV-1 VP22 and VP16

Genes UL49 and UL48 of Marek’s disease virus 1 (MDV-1) strain RB1B, encoding the respective homologues of herpes simplex virus type 1 (HSV-1) genes VP22 and VP16, were cloned into a baculovirus vector. Seven anti-VP22 MAbs and one anti-VP16 MAb were generated and used to identify the tegument proteins in cells infected lytically with MDV-1.

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Microfossils and paleoenvironments in deep subsurface basalt samples

Secondary minerals near and within fractures in Columbia River basalts contain objects the size and shape of bacteria. These bacteriomorphs are most commonly rods or ellipses but also include cocci and diplococci forms, vibrioids and club-shaped rods, and associated pairs of objects that suggest cellular division by binary fission. Secondary minerals associated with, enclosing, and making up bacteriomorphs include iron oxyhydroxides, sulfides, and smectites containing ferrous iron. The secondary minerals are intimately intermixed with kerogen. Moreover ; bacteriomorphs in the pyrite consist of kerogen. Careful consideration of mineral associations, the occurrence of organic carbon, and the spatial context of bacteriomorphs indicate that they are microfossils. The association of microfossils with minerals formed in reducing environments suggests an ancient ecosystem dominated at least. in part by sulfate-reducing bacteria, similar to communities within these basalts today.

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Microscopic physical biomarkers in carbonate hot springs : Implications in the search for life on Mars

Physical evidence of life (physical biomarkers) from the deposits of carbonate hot springs were documented at the scale of microorganisms-submillimeter to submicrometer. The four moderate-temperature (57 to 72 degrees C), neutral pH springs reported on in this study, support diverse communities of bacteria adapted to specific physical and chemical conditions. Some of the microbes coexist with travertine deposits in endolithic communities. In other cases, the microbes are rapidly coated and destroyed by precipitates but leave distinctive mineral fabrics. Some microbes adapted to carbonate hot springs produce an extracellular polymeric substance which forms a three-dimensional matrix with living cells and cell remains, known as a biofilm.

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Molecular cloning of a putative alpha 3-fucosyltransferase from Schistosoma mansoni

Alpha 3-fucosylation of protein or lipid substrates is an important component of the host/parasite interactions during schistosomiasis. In this process, alpha 3-fucosyltransferases (alpha 3-FucTs) are considered as key enzymes ensuring both parasite survival and :adaptation in their (in)vertebrate hosts. In this paper, we report the molecular cloning of a putative alpha 3-FucT from Schistosoma, mansoni that we termed SmFucTA. The full-length SmFucTA encodes a typical transmembrane type 11 protein with a short cytoplasmic domain, a transmembrane segment and a long C-terminal catalytic domain. In this region, the GDP-fucose binding site is well conserved whereas the putative acceptor site displays sequence divergence compared to the corresponding region from vertebrate and invertebrate alpha 3-FucTs. Southern blot analysis suggested that SmFucTA is present as several copies or has highly related counterparts in the S. mansoni genome. Northern blot revealed a single SmFucTA transcript at 2 kb in adult worms. Affinity purified antibodies directed against recombinant SmFucTA identified a 50 kDa native protein that localizes to the subtegumental and parenchymal regions of adult worms. (C) 2000 Elsevier Science B,V. All rights reserved.

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Mono- and bimetallic lanthanide(III) phenolic cryptates obtained by template reaction : solid state structure, photophysical properties and relaxivity

We report here a structural and photophysical study of lanthanide monometallic complexes with the macrobicyclic axial phenolic cryptand N[(CH2)(2)N=CH-R-CH=N(CH2)(2)](3)N (R=m-C6H2OH-2-Me-5) L as well as of bimetallic complexes with its de-protonated form (L-3H)(3-). The X-ray crystal structure of [DyL(NO3)](NO3)(2). 2CH(3)CN . 0.5H(2)O shows the metal ion being asymmetrically positioned into the macrobicyclic cavity and bonded to seven donor atoms of L and two oxygen atoms of a bidentate nitrate ion. The X-ray crystal structure of the bimetallic cryptate, [Dy-2(L-3H)(NO3)(2)](NO3). 3H(2)O . MeOH, confirms that both Dy(III) ions are held into the cavity of the cryptand at a very short distance from each other, 3.4840(4) Angstrom.

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Neutrophil polarity and locomotion are associated with surface redistribution of leukosialin (CD43), an antiadhesive membrane molecule

This study analyzed the behavior of an antiadhesive membrane molecule, CD43, in neutrophil polarization and locomotion. CD43 cross-linking by antibodies induced neutrophil locomotion, with CD43 molecules clustered at the uropod of polarized neutrophils. In contrast, CD11b/CD18 cross-linking by antibodies did not affect either cell polarization or locomotion. Stimulation of suspended or adherent neutrophils with chemotactic peptide results in cell polarization and locomotion and a concomitant redistribution of CD43 to the uropod.

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