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91.
92.
Weisser J Riemer S Schmidl M Suva LJ Pöschl E Bräuer R von der Mark K 《Experimental cell research》2002,279(1):1-13
Differentiation and growth of chondrocytes in fetal growth plates of vertebrate long bones and ribs appear to occur in a gradual, continuous manner between the resting zone through the proliferation zone, maturation zone, and upper and lower hypertrophic zones, with a continuous increase in cell size up to 10-fold of the volume of a resting chondrocyte. Here we provide evidence, however, that after centrifugation through a continuous Percoll gradient growth plate chondrocytes separate into four distinct cell populations (B1 to B4) which differ markedly in density, size, and gene expression. These populations collect in the absence of any phase borders in the gradient which might serve as concentration barriers. Fractions B1 and B2 contained the largest cells with the lowest buoyant density and showed the highest expression levels for type X collagen (Col X), but only the B1 population expressed high levels of matrix metalloproteinase-13 (collagenase 3). Cells in fraction B3 were significantly smaller and expressed little Col X, while cells in fraction B4 were of similar size to cells in the resting zone without significant Col X expression. The highest levels of parathyroid hormone (PTH)/PTH-related peptide (PTHrP) receptor (PTHR-1), and Indian hedgehog (Ihh) expression were also found in the hypertrophic fractions B1 and B2 and not in the prehypertrophic fraction B3, as expected from in situ hybridization data on PTHR-1 expression in fetal rodent or chicken growth plates. Incubation of fractions B1 to B3 with the amino-terminal fragments PTH (1-34) or PTHrP (1-40) suppressed the expression of Col X and PTHR-1 by more than 50% and the expression of Ihh nearly completely. In contrast, the mid-regional PTH fragment PTH (28-48) and PTH (52-84) consistently stimulated the expression of PTHR-1 by 10-20% in fractions B1 to B3. These findings confirm the existence of distinct differentiation stages within chondrocytes of the growth plate and support the hypothesis proposed by Vortkamp et al. (Science 273(1996)613) of a regulatory feedback loop of Ihh and PTH/PTHrP fragments controlling the differentiation of proliferating to prehypertrophic chondrocytes, but extend the ability to respond to PTH/PTHrP hypertrophic chondrocytes. 相似文献
93.
Rectus femoris transfer surgery is performed to convert the rectus femoris muscle from a knee extensor to a knee flexor. In this surgery, the distal tendon of the rectus femoris is detached from the patella and reattached to one of the knee flexor tendons. The outcomes of this procedure are variable, and it is not known if the surgery successfully converts the muscle to a knee flexor. We measured the motion of muscle tissue within the rectus femoris and vastus intermedius during knee extension in 10 unimpaired control subjects (10 limbs) and 6 subjects (10 limbs) after rectus femoris transfer using cine phase-contrast magnetic resonance imaging. Displacements of the vastus intermedius during knee extension were similar between control and tendon transfer subjects. In the control subjects, the rectus femoris muscle consistently moved in the direction of the knee extensors and displaced more than the vastus intermedius. The rectus femoris also moved in the direction of the knee extensors in the tendon transfer subjects; however, the transferred rectus femoris displaced less than the vastus intermedius. These results suggest that the rectus femoris is not converted to a knee flexor after its distal tendon is transferred to the posterior side of the knee, but its capacity for knee extension is diminished by the surgery. 相似文献
94.
C Ramos I Sch?dtler-Siwon L Ortiz-Ortiz 《Journal of immunology (Baltimore, Md. : 1950)》1979,122(4):1243-1247
Infection with Trypanosoma cruzi decreases the ability of spleen cells from mice to respond to either T cell, concanavalin A (Con A), or B cell, lipopolysaccharide (LPS), mitogens. The effect of infection on the mitogenic response depends on the elapsed time between the day of infection and the time of mitogen presentation. Responses early in infection are normal, whereas later responses to either mitogen are depressed. Spleen cells from late trypanosome-infected mice inhibit the ability of normal spleen cells to respond to Con A or LPS. The cell in the T. cruzi-infected spleen cells responsible for this effect is nonadherent, sensitive to treatment with anti-mouse thymus serum plus complement, but insensitive to treatment with anti-immunoglobulin plus complement. These data indicate that infection with T. cruzi elicits over time the generation of T cells suppressive to T and B cell mitogenic responses. 相似文献
95.
96.
Pesenti ME Spinelli S Bezirard V Briand L Pernollet JC Tegoni M Cambillau C 《Journal of molecular biology》2008,380(1):158-169
The behavior of insects and their perception of their surroundings are driven, in a large part, by odorants and pheromones. This is especially true for social insects, such as the honey bee, where the queen controls the development and the caste status of the other individuals. Pheromone perception is a complex phenomenon relying on a cascade of recognition events, initiated in antennae by pheromone recognition by a pheromone-binding protein and finishing with signal transduction at the axon membrane level. With to the objective of deciphering this initial step, we have determined the structures of the bee antennal pheromone-binding protein (ASP1) in the apo form and in complex with the main component of the queen mandibular pheromonal mixture, 9-keto-2(E)-decenoic acid (9-ODA) and with nonpheromonal components. In the apo protein, the C terminus obstructs the binding site. In contrast, ASP1 complexes have different open conformations, depending on the ligand shape, leading to different volumes of the binding cavity. The binding site integrity depends on the C terminus (111-119) conformation, which involves the interplay of two factors; i.e. the presence of a ligand and a low pH. Ligand binding to ASP1 is favored by low pH, opposite to what is observed with other pheromone-binding proteins, such as those of Bombyx mori and Anopheles gambiae. 相似文献
97.
Mukhran Khundadze Katrin Kollmann Nicole Koch Christoph Biskup Sandor Nietzsche Geraldine Zimmer J. Christopher Hennings Antje K. Huebner Judit Symmank Amir Jahic Elena I. Ilina Kathrin Karle Ludger Sch?ls Michael Kessels Thomas Braulke Britta Qualmann Ingo Kurth Christian Beetz Christian A. Hübner 《PLoS genetics》2013,9(12)
Hereditary spastic paraplegias (HSPs) are characterized by progressive weakness and spasticity of the legs because of the degeneration of cortical motoneuron axons. SPG15 is a recessively inherited HSP variant caused by mutations in the ZFYVE26 gene and is additionally characterized by cerebellar ataxia, mental decline, and progressive thinning of the corpus callosum. ZFYVE26 encodes the FYVE domain-containing protein ZFYVE26/SPASTIZIN, which has been suggested to be associated with the newly discovered adaptor protein 5 (AP5) complex. We show that Zfyve26 is broadly expressed in neurons, associates with intracellular vesicles immunopositive for the early endosomal marker EEA1, and co-fractionates with a component of the AP5 complex. As the function of ZFYVE26 in neurons was largely unknown, we disrupted Zfyve26 in mice. Zfyve26 knockout mice do not show developmental defects but develop late-onset spastic paraplegia with cerebellar ataxia confirming that SPG15 is caused by ZFYVE26 deficiency. The morphological analysis reveals axon degeneration and progressive loss of both cortical motoneurons and Purkinje cells in the cerebellum. Importantly, neuron loss is preceded by accumulation of large intraneuronal deposits of membrane-surrounded material, which co-stains with the lysosomal marker Lamp1. A density gradient analysis of brain lysates shows an increase of Lamp1-positive membrane compartments with higher densities in Zfyve26 knockout mice. Increased levels of lysosomal enzymes in brains of aged knockout mice further support an alteration of the lysosomal compartment upon disruption of Zfyve26. We propose that SPG15 is caused by an endolysosomal membrane trafficking defect, which results in endolysosomal dysfunction. This appears to be particularly relevant in neurons with highly specialized neurites such as cortical motoneurons and Purkinje cells. 相似文献
98.
Chiara V. Segré Silvia Senese Sara Loponte Stefano Santaguida Paolo Soffientini Gabriela Grigorean 《MABS-AUSTIN》2016,8(1):37-42
Histone deacetylases (HDACs) are modification enzymes that regulate a plethora of biological processes. HDAC1, a crucial epigenetic modifier, is deregulated in cancer and subjected to a variety of post-translational modifications. Here, we describe the generation of a new monoclonal antibody that specifically recognizes a novel highly dynamic prophase phosphorylation of serine 406-HDAC1, providing a powerful tool for detecting early mitotic cells. 相似文献
99.
Many mountain ranges have been strongly glaciated during the Quaternary ice ages, and the locations of glacial refugia of mountain plants have been debated for a long time. A series of detailed molecular studies, investigating intraspecific genetic variation of mountain plants in the European Alps, now allows for a first synopsis. A comparison of the phylogeographic patterns with geological and palaeoenvironmental data demonstrates that glacial refugia were located along the southwestern, southern, eastern and northern border of the Alps. Additional glacial refugia were present in central Alpine areas, where high-elevation plants survived the last glaciation on ice-free mountain tops. The observed intraspecific phylogeographies suggest general patterns of glacial survival, which conform to well-known centres of Alpine species diversity and endemism. This implies that evolutionary or biogeographic processes induced by climatic fluctuations act on gene and species diversity in a similar way. 相似文献
100.
Emanuele Zonaro Elena Piacenza Alessandro Presentato Francesca Monti Rossana Dell’Anna Silvia Lampis Giovanni Vallini 《Microbial cell factories》2017,16(1):215
Background
Bacteria have developed different mechanisms for the transformation of metalloid oxyanions to non-toxic chemical forms. A number of bacterial isolates so far obtained in axenic culture has shown the ability to bioreduce selenite and tellurite to the elemental state in different conditions along with the formation of nanoparticles—both inside and outside the cells—characterized by a variety of morphological features. This reductive process can be considered of major importance for two reasons: firstly, toxic and soluble (i.e. bioavailable) compounds such as selenite and tellurite are converted to a less toxic chemical forms (i.e. zero valent state); secondly, chalcogen nanoparticles have attracted great interest due to their photoelectric and semiconducting properties. In addition, their exploitation as antimicrobial agents is currently becoming an area of intensive research in medical sciences.Results
In the present study, the bacterial strain Ochrobactrum sp. MPV1, isolated from a dump of roasted arsenopyrites as residues of a formerly sulfuric acid production near Scarlino (Tuscany, Italy) was analyzed for its capability of efficaciously bioreducing the chalcogen oxyanions selenite (SeO3 2?) and tellurite (TeO3 2?) to their respective elemental forms (Se0 and Te0) in aerobic conditions, with generation of Se- and Te-nanoparticles (Se- and TeNPs). The isolate could bioconvert 2 mM SeO3 2? and 0.5 mM TeO3 2? to the corresponding Se0 and Te0 in 48 and 120 h, respectively. The intracellular accumulation of nanomaterials was demonstrated through electron microscopy. Moreover, several analyses were performed to shed light on the mechanisms involved in SeO3 2? and TeO3 2? bioreduction to their elemental states. Results obtained suggested that these oxyanions are bioconverted through two different mechanisms in Ochrobactrum sp. MPV1. Glutathione (GSH) seemed to play a key role in SeO3 2? bioreduction, while TeO3 2? bioconversion could be ascribed to the catalytic activity of intracellular NADH-dependent oxidoreductases. The organic coating surrounding biogenic Se- and TeNPs was also characterized through Fourier-transform infrared spectroscopy. This analysis revealed interesting differences among the NPs produced by Ochrobactrum sp. MPV1 and suggested a possible different role of phospholipids and proteins in both biosynthesis and stabilization of such chalcogen-NPs.Conclusions
In conclusion, Ochrobactrum sp. MPV1 has demonstrated to be an ideal candidate for the bioconversion of toxic oxyanions such as selenite and tellurite to their respective elemental forms, producing intracellular Se- and TeNPs possibly exploitable in biomedical and industrial applications.