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131.
Gagiannis D Orthmann A Danssmann I Schwarzkopf M Weidemann W Horstkorte R 《Glycoconjugate journal》2007,24(2-3):125-130
Sialic acids are widely expressed as terminal carbohydrates on glycoconjugates of eukaryotic cells. They are involved in a
variety of cellular functions, such as cell adhesion or signal recognition. The key enzyme of sialic acid biosynthesis is
the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (GNE), which catalyzes the first two steps of sialic acid biosynthesis in the cytosol. Previously,
we have shown that inactivation of the GNE by gene targeting causes early embryonic lethality in mice, whereas heterozygous
GNE-deficient mice are vital. In this study we compared the amount of membrane-bound sialic acids of wildtype mice with those
of heterozygous GNE-deficient mice. For that we quantified membrane-bound sialic acid concentration in various organs of wildtype-
and heterozygous GNE-deficient mice. We found an organ-specific reduction of membrane-bound sialic acids in heterozygous GNE-deficient
mice. The overall reduction was 25%. Additionally, we analyzed transferrin and polysialylated neural cell adhesion molecule
(NCAM) by one- or two-dimensional gel electrophoresis. Transferrin-expression was unchanged in heterozygous GNE-deficient
mice; however the isoelectric point of transferrin was shifted towards basic pH, indicating a reduced sialylation. Furthermore,
the expression of polysialic acids on NCAM was reduced in GNE-deficient mice.
Daniel Gagiannis and André Orthmann have contributed equally to this work. 相似文献
132.
Kim SJ Lee BH Lee YS Kang KS 《Biochemical and biophysical research communications》2007,360(3):593-599
Niemann-Pick type C disease (NPC) is a neurodegenerative and lipid storage disorder for which no effective treatment is known. We previously reported that neural stem cells derived from NPC1 mice showed impaired self-renewal and differentiation. We examined whether valproic acid (VPA), a histone deacetylase inhibitor, could enhance neuronal differentiation and recover defective cholesterol metabolism in neural stem cells (NSCs) from NPC1-deficient mice (NPC1(-/-)). VPA could induce neuronal differentiation and restore impaired astrocytes in NSCs from NPC1(-/-) mice. Importantly, an increasing level of cholesterol within NSCs from NPC1(-/-) mice could be reduced by VPA. Moreover, essential neurotrophic genes (TrkB, BDNF, MnSoD, and NeuroD) were up-regulated through the repression of the REST/NRSF and HDAC complex by the VPA treatment. Up-regulated neurotrophic genes were able to enhance neural differentiation and cholesterol homeostasis in neural stem cells from NPC1(-/-) mice. In this study, we suggested that, along with cholesterol homeostasis, impaired neuronal differentiation and abnormal morphology of astrocytes could be rescued by the inhibition of HDAC and REST/NRSF activity induced by VPA treatment. 相似文献
133.
G. Marsat G. S. Pollack 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(6):625-633
In crickets, auditory information about ultrasound is carried bilaterally to the brain by the AN2 neurons. The ON1 neuron
provides contralateral inhibitory input to AN2, thereby enhancing bilateral contrast between the left and right AN2s, an important
cue for sound localization. We examine how the structures of the spike trains of these neurons affect this inhibitory interaction.
As previously shown for AN2, ON1 responds to salient peaks in stimulus amplitude with bursts of spikes. Spike bursts, but
not isolated spikes, reliably signal the occurrence of specific features of the stimulus. ON1 and AN2 burst at similar times
relative to the amplitude envelope of the stimulus, and bursts are more tightly time-locked to stimulus feature than the isolated
spikes. As a consequence, spikes that, in the absence of contralateral inhibition, would occur within AN2 bursts are more
likely to be preceded by spikes in ON1 (mainly also in bursts) than are isolated AN2 spikes. This leads to a large decrease
in the burst rate of the inhibited AN2. We conclude that the match in coding properties of ON1 and AN2 allows contralateral
inhibition to be most efficient for those portions of the response that carry the behaviourally relevant information, i.e.
for bursts.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
134.
135.
136.
Culture and neural differentiation of rat bone marrow mesenchymal stem cells in vitro 总被引:23,自引:0,他引:23
Lei Z Yongda L Jun M Yingyu S Shaoju Z Xinwen Z Mingxue Z 《Cell biology international》2007,31(9):916-923
Adult bone marrow mesenchymal stem cells (MSCs) can differentiate into several types of mesenchymal cells, including osteocytes, chondrocytes, and adipocytes, but can also differentiate into non-mesenchymal cells, such as neural cells, under appropriate experimental conditions. Until now, many protocols for inducing neuro-differentiation in MSCs in vitro have been reported. But due to the differences in MSCs' isolation and culture conditions, the results of previous studies lacked consistency and comparability. In this study, we induced differentiation into neural phenotype in the same MSCs population by three different treatments: beta-mercaptoethanol, serum-free medium and co-cultivation with fetal mouse brain astrocytes. In all of the three treatments, MSCs could express neural markers such as NeuN or GFAP, associating with remarkable morphological modifications. But these treatments led to neural phenotype in a non-identical manner. In serum-free medium, MSCs mainly differentiated into neuron-like cells, expressing neuronal marker NeuN, and BME can promote this process. Differently, after co-culturing with astrocytes, MSCs leaned to differentiate into GFAP(+) cells. These data confirmed that MSCs can exhibit plastic neuro-differentiational potential in vitro, depending on the protocols of inducement. 相似文献
137.
Increasing worldwide resistance to acaricides necessitates greater research on the identification of potential acaricide targets
in ticks to aid in the control of these serious pests of medical and veterinary importance. Historically, and most likely
in the future, acaricide targets are largely of neural origin, but our knowledge of tick neurobiology is surprisingly limited.
The tick central nervous system is a fused nerve mass, termed the synganglion. Tick synganglion material is relatively easily
accessible to most researchers and employing modern amplification methods of complementary-DNA construction is readily amenable
for gene cloning investigations. The various tick neurotransmitter systems are described with emphasis on our current knowledge
of both existing and potential acaricide targets at the molecular level. We describe the impact of mass gene sequencing (expressed
sequence tag and genome projects), advances in bioinformatics and RNA-interference on target identification and validation. 相似文献
138.
Catania MV D'Antoni S Bonaccorso CM Aronica E Bear MF Nicoletti F 《Molecular neurobiology》2007,35(3):298-307
Group I metabotropic glutamate receptors (mGlu1 and mGlu5) are coupled to polyphosphoinositide hydrolysis and are involved
in activity-dependent forms of synaptic plasticity, both during development and in the adult life. Group I mGlu receptors
can also regulate proliferation, differentiation, and survival of neural stem/progenitor cells, which further support their
role in brain development. An exaggerated response to activation of mGlu5 receptors may underlie synaptic dysfunction in Fragile
X syndrome, the most common inherited form of mental retardation. In addition, group I mGlu receptors are overexpressed in
dysplastic neurons of focal cortical dysplasia and hemimegaloencephaly, which are disorders of cortical development associated
with chronic epilepsy. Drugs that block the activity of group I mGlu receptors (in particular, mGlu5 receptors) are potentially
helpful for the treatment of Fragile X syndrome and perhaps other neurodevelopmental disorders. 相似文献
139.
Adaptive resonance theory (ART) demonstrates how the brain learns to recognize and categorize vast amounts of information
by using top–down expectations and attentional focusing. ART 3, one member of the ART family, embeds the computational properties
of the chemical synapse in its search process, but it converges slowly and is lack of stability when being applied in pattern
recognition and analysis. To overcome these problems, Nitric Oxide (NO), which serves as a newly discovered retrograde messenger
in Long-Term Potentiation (LTP), is introduced in retrograde adaptive resonance theory (ReART) model presented in this paper.
In the presented model a novel search hypothesis is proposed to incorporate angle and amplitude information of an external
input vector to decide whether the input matches the long-term memory (LTM) weights of an active node or not, and the embedded
NO retrograde mechanism makes the search procedure a closed loop, which improves the stability and convergence speed of the
transmitter releasing mechanism in a synapse. To make the model more adaptive and practical, a forgetting mechanism is built
to improve the weights updating process. Experimental results indicate that the proposed ReART model achieves low error rate,
fast convergence and self-organizing weights regulation.
Action Editor: Christiane Linster 相似文献
140.
Due to its intermediate complexity and its sophisticated genetic tools, the larval brain of Drosophila is a useful experimental system to study the mechanisms that control the generation of cell diversity in the CNS. In order to gain insight into the neuronal and glial lineage specificity of neural progenitor cells during postembryonic brain development, we have carried an extensive mosaic analysis throughout larval brain development. In contrast to embryonic CNS development, we have found that most postembryonic neurons and glial cells of the optic lobe and central brain originate from segregated progenitors. Our analysis also provides relevant information about the origin and proliferation patterns of several postembryonic lineages such as the superficial glia and the medial-anterior Medulla neuropile glia. Additionally, we have studied the spatio-temporal relationship between gcm expression and gliogenesis. We found that gcm expression is restricted to the post-mitotic cells of a few neuronal and glial lineages and it is mostly absent from postembryonic progenitors. Thus, in contrast to its major gliogenic role in the embryo, the function of gcm during postembryonic brain development seems to have evolved to the specification and differentiation of certain neuronal and glial lineages. 相似文献