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101.
Helmut Bäumlein James Pustell Ulrich Wobus Steven T. Case Fotis C. Kafatos 《Journal of molecular evolution》1986,24(1-2):72-82
Summary The 3-end sequences of two nonallelic genes derived from the Balbiani ring c (BRc) locus ofChironomus thummi are described. Only one of the genes appears to be transcribed abundantly in normal late larval salivary glands. The two sequences are highly similar, even in the 3 untranslated regions, but sharply diverge beyond the polyadenylation site. Together with evidence from the 3 ends of BR1 and BR2 genes ofC. pallidivittatus andC. tentans, independently characterized by others, this result suggests the existence of a sequence-homogenization mechanism that operates across the 3 ends of all BR genes characterized to date. The 3-terminal coding region of each BRc gene is divided into two portions by a short intron. The upstream portion is homologous to and continuous with the tandem repeats that make up the internal core of each BR gene; however, that portion is variant in sequence relative to the core, and apparently is not subject to the homogenization process that operates on the core repeats. The portion downstream of the intron encodes a unique, 111-residue polypeptide highly different from the rest of the BRc product. The evolution of the various segments of the BRc genes is discussed. 相似文献
102.
Mitochondria are essential organelles with multiple functions, especially in energy metabolism. Recently, an increasing number of data has highlighted the role of mitochondria for cellular differentiation processes. Metabolic differences between stem cells and mature derivatives require an adaptation of mitochondrial function during differentiation. In this study we investigated alterations of the mitochondrial phenotype of human mesenchymal stem cells undergoing adipogenic differentiation. Maturation of adipocytes is accompanied by mitochondrial biogenesis and an increase of oxidative metabolism. Adaptation of the mt phenotype during differentiation is reflected by changes in the distribution of the mitochondrial network as well as marked alterations of gene expression and organization of the oxidative phosphorylation system (OXPHOS). Distinct differences in the supramolecular organization forms of cytochrome c oxidase (COX) were detected using 2D blue native (BN)-PAGE analysis. Most remarkably we observed a significant increase in the abundance of OXPHOS supercomplexes in mitochondria, emphasizing the change of the mitochondrial phenotype during adipogenic differentiation. 相似文献
103.
Taube S Perry JW McGreevy E Yetming K Perkins C Henderson K Wobus CE 《Journal of virology》2012,86(10):5584-5593
Human norovirus infections are the most common cause of acute nonbacterial gastroenteritis in humans worldwide, and glycan binding plays an important role in the susceptibility to these infections. However, due to the lack of an efficient cell culture system or small animal model for human noroviruses, little is known about the biological role of glycan binding during infection. Murine noroviruses (MNV) are also enteric viruses that bind to cell surface glycans, but in contrast to their human counterparts, they can be grown in tissue culture and a small animal host. In this study, we determined glycan-binding specificities of the MNV strains MNV-1 and CR3 in vitro, identified molecular determinants of glycan binding, and analyzed infection in vivo. We showed that unlike MNV-1, CR3 binding to murine macrophages was resistant to neuraminidase treatment and glycosphingolipid depletion. Both strains depended on N-linked glycoproteins for binding, while only MNV-1 attachment to macrophages was sensitive to O-linked glycoprotein depletion. In vivo, CR3 showed differences in tissue tropism compared to MNV-1 by replicating in the large intestine. Mapping of a glycan-binding site in the MNV-1 capsid by reverse genetics identified a region topologically similar to the histo-blood group antigen (HBGA)-binding sites of the human norovirus strain VA387. The recombinant virus showed distinct changes in tissue tropism compared to wild-type virus. Taken together, our data demonstrate that MNV strains evolved multiple strategies to bind different glycan receptors on the surface of murine macrophages and that glycan binding contributes to tissue tropism in vivo. 相似文献
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105.
A pea seed mutant affected in the differentiation of the embryonic epidermis is impaired in embryo growth and seed maturation 总被引:4,自引:0,他引:4
Borisjuk L Wang TL Rolletschek H Wobus U Weber H 《Development (Cambridge, England)》2002,129(7):1595-1607
During legume seed development the epidermis of the embryos differentiates into a transfer cell layer which mediates nutrient uptake during the storage phase. This specific function of the epidermal cells is acquired at the onset of embryo maturation. We investigated this process in the pea seed mutant E2748. The epidermal cells of the mutant embryo, instead of turning into transfer cells, enlarge considerably and become vacuolated and tightly associated with adjacent seed tissues. Expression of a sucrose transporter gene that is upregulated in wild-type transfer cells decreases in the mutant and changes its spatial pattern. This indicates that the outermost cell layer of mutant cotyledons cannot acquire transfer cell morphology but loses epidermal cell identity and does not function as a sucrose uptake system. Seed coat growth as well as composition, concentration and dynamics of sugars within the endospermal vacuole are unchanged. The loss of epidermal identity has severe consequences for further embryo development and is followed by disruption of the symplast within the parenchyma, the breach of the developmental gradient, lower sucrose and starch levels and initiation of callus-like growth. It is concluded that the E2748 gene controls differentiation of the cotyledonary epidermis into transfer cells and thus is required for the regional specialisation with a function in embryo nutrition. 相似文献
106.
Huidan Zhang Shelley K. Cockrell Abimbola O. Kolawole Assaf Rotem Adrian W. R. Serohijos Connie B. Chang Ye Tao Thomas S. Mehoke Yulong Han Jeffrey S. Lin Nicholas S. Giacobbi Andrew B. Feldman Eugene Shakhnovich David A. Weitz Christiane E. Wobus James M. Pipas 《Journal of virology》2015,89(15):7722-7734
107.
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109.
Anna M. Wobus Gerd Wallukat Jürgen Hescheler 《Differentiation; research in biological diversity》1991,48(3):173-182
Abstract. A defined cultivation system was developed for the differentiation of pluripotent embryonic stem cells of the mouse into spontaneously beating cardiomyocytes, allowing investigations of chronotropic responses, as well as electrophysiological studies of different cardioactive drugs in vitro.
The β-adrenoceptor agonists (—)isoprenaline and clenbuterol, the mediators of cAMP metabolism, forsko-lin and isobutylmethylxanthine (IBMX), the α1 -adreno-ceptor agonist (—)phenylephrine, and the heart glyco-side digitoxine induced a positive, the muscarinic cholin-oceptor agonist carbachol and L-type Ca2+ channel blockers nisoldipine, gallopamil and diltiazem induced a negative chronotropic response.
In early differentiated cardiomyocytes β1 -, α1 -, but not β2 -adrenoceptors, cholinoceptors, as well as L-type Ca2+ channels participated in the chronotropic response. In terminally differentiated cardiomyocytes β2 -adrenoceptors and digitoxine responses were also functionally expressed.
The contractions of spontaneously beating cardiomyocytes were concommitant with rhythmic action potentials very similar to those described for embryonic cardiomyocytes and sinusnode cells. We conclude that cardiomyocytes differentiating from pluripotent embryonic stem cells are able to develop adrenoceptors and cholinoceptors and signal transduction pathways as well as L-type Ca2+ channels as a consequence of cell-cell interactions during embryoid body formation in vitro, independent of the development in living organisms.
The cellular system described may be useful as in vitro assay for toxicological investigations of chronotropic drugs and a model system for studying commitment and cellular differentiation in vitro. 相似文献
The β-adrenoceptor agonists (—)isoprenaline and clenbuterol, the mediators of cAMP metabolism, forsko-lin and isobutylmethylxanthine (IBMX), the α
In early differentiated cardiomyocytes β
The contractions of spontaneously beating cardiomyocytes were concommitant with rhythmic action potentials very similar to those described for embryonic cardiomyocytes and sinusnode cells. We conclude that cardiomyocytes differentiating from pluripotent embryonic stem cells are able to develop adrenoceptors and cholinoceptors and signal transduction pathways as well as L-type Ca
The cellular system described may be useful as in vitro assay for toxicological investigations of chronotropic drugs and a model system for studying commitment and cellular differentiation in vitro. 相似文献
110.