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141.
Subventricular zone astrocytes are neural stem cells in the adult mammalian brain. 总被引:132,自引:0,他引:132
Neural stem cells reside in the subventricular zone (SVZ) of the adult mammalian brain. This germinal region, which continually generates new neurons destined for the olfactory bulb, is composed of four cell types: migrating neuroblasts, immature precursors, astrocytes, and ependymal cells. Here we show that SVZ astrocytes, and not ependymal cells, remain labeled with proliferation markers after long survivals in adult mice. After elimination of immature precursors and neuroblasts by an antimitotic treatment, SVZ astrocytes divide to generate immature precursors and neuroblasts. Furthermore, in untreated mice, SVZ astrocytes specifically infected with a retrovirus give rise to new neurons in the olfactory bulb. Finally, we show that SVZ astrocytes give rise to cells that grow into multipotent neurospheres in vitro. We conclude that SVZ astrocytes act as neural stem cells in both the normal and regenerating brain. 相似文献
142.
Jos Manuel García-Verdugo Fiona Doetsch Hynek Wichterle Daniel A. Lim Arturo Alvarez-Buylla 《Developmental neurobiology》1998,36(2):234-248
Neural stem cells are maintained in the subventricular zone (SVZ) of the adult mammalian brain. Here, we review the cellular organization of this germinal layer and propose lineage relationships of the three main cell types found in this area. The majority of cells in the adult SVZ are migrating neuroblasts (type A cells) that continue to proliferate. These cells form an extensive network of tangentially oriented pathways throughout the lateral wall of the lateral ventricle. Type A cells move long distances through this network at high speeds by means of chain migration. Cells in the SVZ network enter the rostral migratory stream (RMS) and migrate anteriorly into the olfactory bulb, where they differentiate into interneurons. The chains of type A cells are ensheathed by slowly proliferating astrocytes (type B cells), the second most common cell type in this germinal layer. The most actively proliferating cells in the SVZ, type C, form small clusters dispersed throughout the network. These foci of proliferating type C cells are in close proximity to chains of type A cells. We discuss possible lineage relationships among these cells and hypothesize which are the neural stem cells in the adult SVZ. In addition, we suggest that interactions between type A, B, and C cells may regulate proliferation and initial differentiation within this germinal layer. © 1998 John Wiley & Sons, Inc. J Neurobiol 36: 234–248, 1998 相似文献
143.
Markus Beck Erlach Joerg Koehler Edson CruscaJr. Claudia E. Munte Masatsune Kainosho Werner Kremer Hans Robert Kalbitzer 《Journal of biomolecular NMR》2017,69(2):53-67
For evaluating the pressure responses of folded as well as intrinsically unfolded proteins detectable by NMR spectroscopy the availability of data from well-defined model systems is indispensable. In this work we report the pressure dependence of 13C chemical shifts of the side chain atoms in the protected tetrapeptides Ac-Gly-Gly-Xxx-Ala-NH2 (Xxx, one of the 20 canonical amino acids). Contrary to expectation the chemical shifts of a number of nuclei have a nonlinear dependence on pressure in the range from 0.1 to 200 MPa. The size of the polynomial pressure coefficients B 1 and B 2 is dependent on the type of atom and amino acid studied. For HN, N and Cα the first order pressure coefficient B 1 is also correlated to the chemical shift at atmospheric pressure. The first and second order pressure coefficients of a given type of carbon atom show significant linear correlations suggesting that the NMR observable pressure effects in the different amino acids have at least partly the same physical cause. In line with this observation the magnitude of the second order coefficients of nuclei being direct neighbors in the chemical structure also are weakly correlated. The downfield shifts of the methyl resonances suggest that gauche conformers of the side chains are not preferred with pressure. The valine and leucine methyl groups in the model peptides were assigned using stereospecifically 13C enriched amino acids with the pro-R carbons downfield shifted relative to the pro-S carbons. 相似文献
144.
Zhifei Li Clement Bommier Zhi Sen Chong Zelang Jian Todd Wesley Surta Xingfeng Wang Zhenyu Xing Joerg C. Neuefeind William F. Stickle Michelle Dolgos P. Alex Greaney Xiulei Ji 《Liver Transplantation》2017,7(18)
Hard carbon is the leading candidate anode for commercialization of Na‐ion batteries. Hard carbon has a unique local atomic structure, which is composed of nanodomains of layered rumpled sheets that have short‐range local order resembling graphene within each layer, but complete disorder along the c‐axis between layers. A primary challenge holding back the development of Na‐ion batteries is that a complete understanding of the structure–capacity correlations of Na‐ion storage in hard carbon has remained elusive. This article presents two key discoveries: first, the characteristics of hard carbons structure can be modified systematically by heteroatom doping, and second, that these structural changes greatly affect Na‐ion storage properties, which reveals the mechanisms for Na storage in hard carbon. Specifically, via P or S doping, the interlayer spacing is dilated, which extends the low‐voltage plateau capacity, while increasing the defect concentrations with P or B doping leads to higher sloping sodiation capacity. The combined experimental studies and first principles calculations reveal that it is the Na‐ion‐defect binding that corresponds to the sloping capacity, while the Na intercalation between graphenic layers causes the low‐potential plateau capacity. The understanding suggests a new design principle of hard carbon anode: more reversibly binding defects and dilated turbostratic domains, given that the specific surface area is maintained low. 相似文献
145.
Little association of biological trait values with environmental variables in invasive alien round goby (Neogobius melanostomus)
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Alexander F. Cerwenka Alfredo Pagnotta Carolin Böker Joerg Brandner Juergen Geist Ulrich K. Schliewen 《Ecology and evolution》2017,7(12):4076-4085
The relative importance of species‐specific biological trait characteristics and environmental factors in invasions of nonindigenous species remains controversial because both have mostly been studied independently. Thus, the main objective of this study was to examine the correlation of biological traits with environmental variation in the globally invasive round goby Neogobius melanostomus from the upper Danube River. Based on a sample of 653 specimens along a continuous 200 km river pathway, links between nine environmental factors (substrate‐type, six water measurements, and the communities of fishes and macroinvertebrates) and seven biological traits (nutritional and energetic status, trade‐offs of parasite resistance and resource allocation, and three growth proxies) were analyzed. Biological trait values of N. melanostomus hardly correlated with the environment, could not explain invasion progress and imply a general low overall importance for invasion success. Instead, alternative individual life‐history trajectories appear to determine invasion success. This is in line with up to 15% of all specimens having outlying biological trait values of potential adaptive value, suggesting a considerable importance of adaptive trait variation among single individuals for the whole invasion progress. This “individual trait utility hypothesis” gives an alternative explanation for success of invasive species by single individuals carrying particular traits, and it should be specifically targeted and analyzed at currently invaded sites. 相似文献
146.
147.
Chemosensory neurons in the olfactory epithelium (OE) project axonal processes to the olfactory bulb (OB) of the brain. During
embryonic stages, on their trajectory to the OB, the outgrowing axons traverse the so-called cribriform mesenchyme, which
is located between the OE and the OB. The molecular cues guiding these axons through the cribriform mesenchyme are largely
unknown. To identify molecules influencing the axonal trajectory in the murine cribriform mesenchyme, we performed microarray
analyses focusing on extracellular matrix (ECM) proteins present in this tissue. Thereby, the ECM protein Reelin turned out
to be an interesting candidate. Reelin was found to be expressed by numerous cells in the cribriform mesenchyme during the
embryonic stages when the first axons navigate from the OE to the OB. These cells were closely associated with olfactory axons
and apparently lack glial and neuronal markers. In the mesenchyme underlying the OE, localization of the Reelin protein was
not confined to the Reelin-expressing cells, but it was also observed to be widely distributed in the ECM—most prominently
in regions traversed by olfactory axons. Importantly, these axons were found to be endowed with the Reelin receptor very-low-density
lipoprotein receptor (VLDLR). Finally, Reelin expression was also detectable in neuronal cells of the OB, which are contacted
by VLDLR-positive olfactory axons. In summary, the results of the present study suggest that a Reelin/VLDLR signaling pathway
might contribute to the formation of olfactory projections to the OB and the establishment of initial contacts between the
incoming axons and neurons in the OB.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Funding: This work was supported by the Deutsche Forschungsgemeinschaft. 相似文献
148.
Fabian Klaus Eva-Maria Gehring Agathe Zürn Joerg Laufer Ricco Lindner Nathalie Strutz-Seebohm Jeremy M. Tavaré Jeffrey D. Rothstein Christoph Boehmer Monica Palmada Ivonne Gruner Undine E. Lang Guiscard Seebohm Florian Lang 《Neurochemistry international》2009,54(5-6):372-377
The Na+,glutamate cotransporter EAAT3 is expressed in a wide variety of tissues. It accomplishes transepithelial transport and the cellular uptake of acidic amino acids. Regulation of EAAT3 activity involves a signaling cascade including the phosphatidylinositol-3 (PI3)-kinase, the phosphoinositide dependent kinase PDK1, and the serum and glucocorticoid inducible kinase SGK1. Targets of SGK1 include the mammalian phosphatidylinositol-3-phosphate-5-kinase PIKfyve (PIP5K3). The present experiments explored whether PIKfyve participates in the regulation of EAAT3 activity. To this end, EAAT3 was expressed in Xenopus oocytes with or without SGK1 and/or PIKfyve and glutamate-induced current (Iglu) determined by dual electrode voltage clamp. In Xenopus oocytes expressing EAAT3 but not in water injected oocytes glutamate induced an inwardly directed Iglu. Coexpression of either, SGK1 or PIKfyve, significantly enhanced Iglu in EAAT3 expressing oocytes. The increased Iglu was paralleled by increased EAAT3 protein abundance in the oocyte cell membrane. Iglu and EAAT3 protein abundance were significantly larger in oocytes coexpressing EAAT3, SGK1 and PIKfyve than in oocytes expressing EAAT3 and either, SGK1 or PIKfyve, alone. Coexpression of the inactive SGK1 mutant K127NSGK1 did not significantly alter Iglu in EAAT3 expressing oocytes and completely reversed the stimulating effect of PIKfyve coexpression on Iglu. The stimulating effect of PIKfyve on Iglu was abolished by replacement of the serine by alanine in the SGK consensus sequence (S318APIKfyve). Moreover, additional coexpression of S318APIKfyve significantly blunted Iglu in Xenopus oocytes coexpressing SGK1 and EAAT3. The observations demonstrate that PIKfyve participates in EAAT3 regulation likely downstream of SGK1. 相似文献
149.
Expression of cGMP signaling elements in the Grueneberg ganglion 总被引:1,自引:0,他引:1
The Grueneberg ganglion (GG) is a cluster of neurons localized to the vestibule of the anterior nasal cavity. Based on axonal
projections to the olfactory bulb of the brain, as well as expression of olfactory receptors and the olfactory marker protein,
it is considered a chemosensory subsystem. Recently, it was observed that in mice, GG neurons respond to cool ambient temperatures.
In mammals, coolness-induced responses in highly specialized neuronal cells are supposed to rely on the ion channel TRPM8,
whereas in thermosensory neurons of the nematode worm Caenorhabditis elegans, detection of environmental temperature is mainly mediated by cyclic guanosine monophosphate (cGMP) pathways, in which cGMP
is generated by transmembrane guanylyl cyclases. To unravel the molecular mechanisms underlying coolness-induced responses
in GG neurons, potential expression of TRPM8 in the murine GG was investigated; however, no evidence was found that this ion
channel is present in the GG. By contrast, a substantial number of GG neurons was observed to express the transmembrane guanylyl
cyclase subtype GC-G. In the nose, GC-G expression appears to be confined to the GG since it was not detectable in other nasal
compartments. In the GG, coolness-stimulated responses are only observed in neurons characterized by the expression of the
olfactory receptor V2r83. Interestingly, expression of GC-G in the GG was found in this V2r83-positive subpopulation but not
in other GG neurons. In addition to GC-G, V2r83-positive GG cells also co-express the phosphodiesterase PDE2A. Thus, in summary,
coolness-sensitive V2r83-expressing GG neurons are endowed with a cGMP cascade which might underlie thermosensitivity of these
cells, similar to the cGMP pathway mediating thermosensation in neurons of C. elegans.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
J. Fleischer and K. Mamasuew contributed equally to this work. 相似文献
150.
Katja Conrath Alice S. Pereira Carlos E. Martins Cristina G. Timóteo Pedro Tavares Silvia Spinelli Joerg Kinne Christophe Flaudrops Christian Cambillau Serge Muyldermans Isabel Moura Jose J. G. Moura Mariella Tegoni Aline Desmyter 《Protein science : a publication of the Protein Society》2009,18(3):619-628
Nitric Oxide Reductase (NOR) is an integral membrane protein performing the reduction of NO to N2O. NOR is composed of two subunits: the large one (NorB) is a bundle of 12 transmembrane helices (TMH). It contains a b type heme and a binuclear iron site, which is believed to be the catalytic site, comprising a heme b and a non-hemic iron. The small subunit (NorC) harbors a cytochrome c and is attached to the membrane through a unique TMH. With the aim to perform structural and functional studies of NOR, we have immunized dromedaries with NOR and produced several antibody fragments of the heavy chain (VHHs, also known as nanobodies™). These fragments have been used to develop a faster NOR purification procedure, to proceed to crystallization assays and to analyze the electron transfer of electron donors. BIAcore experiments have revealed that up to three VHHs can bind concomitantly to NOR with affinities in the nanomolar range. This is the first example of the use of VHHs with an integral membrane protein. Our results indicate that VHHs are able to recognize with high affinity distinct epitopes on this class of proteins, and can be used as versatile and valuable tool for purification, functional study and crystallization of integral membrane proteins. 相似文献