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81.
The neurotrophin brain-derived neurotrophic factor (BDNF) has been implicated in the generation and differentiation of new olfactory sensory neurons (OSNs) and in the regulation of branching of OSN axons in their target glomeruli. However, previous reports of BDNF mRNA and protein expression in olfactory epithelium and olfactory bulb (OB) have been inconsistent, raising questions on the proposed roles for BDNF. Here, we report on beta-galactosidase (beta-gal) expression in adult gene-targeted mice where the BDNF promoter drives expression of the Escherichia coli lacZ gene (BDNF(lacZneo) mice). We find that beta-gal is expressed in a small subset of OSNs with axons that reach the olfactory nerve layers throughout the OB. In the OB, we find expression of beta-gal in gamma-aminobutyric acidergic but not dopaminergic periglomerular cells and external tufted cells and in interneurons located in the mitral cell layer. Our results are inconsistent with the regulation of generation and differentiation of new OSNs elicited by the release of BDNF from horizontal basal cells. The results are consistent with a role for BDNF in competitive branching of OSN axons within the glomeruli of the OB. 相似文献
82.
Víctor Faundes William G. Newman Laura Bernardini Natalie Canham Jill Clayton-Smith Bruno Dallapiccola Sally J. Davies Michelle K. Demos Amy Goldman Harinder Gill Rachel Horton Bronwyn Kerr Dhavendra Kumar Anna Lehman Shane McKee Jenny Morton Michael J. Parker Julia Rankin Siddharth Banka 《American journal of human genetics》2018,102(1):175-187
83.
Albright Craig D. Tsai Amy Y. Mar Mei-Heng Zeisel Steven H. 《Neurochemical research》1998,23(5):751-758
Choline availability influences long-term memory in concert with changes in the spatial organization and morphology of septal neurons, however little is known concerning the effects of choline on the hippocampus, a region of the brain also important for memory performance. Pregnant rats on gestational day 12 were fed a choline control (CT), choline supplemented (CS), or choline deficient (CD) diet for 6 days and fetal brain slices were prepared on embryonic day 18 (El8). The hippocampus in these brain slices was studied for the immunohistochemical localization of the growth-related proteins transforming growth factor beta type 1 (TGF1) and GAP43, the cytoskeletal proteins vimentin and microtubule associated protein type 1 (MAP1), and the neuronal cell marker neuron specific enolase (NSE). In control hippocampus, there was weak expression of TGF1 and vimentin proteins, but moderately intense expression of MAP1 protein. These proteins were not homogeneously distributed, but were preferentially localized to cells with large cell bodies located in the central (CA1–CA3) region of the hippocampus, and to the filamentous processes of small cells in the fimbria region. Feeding a choline-supplemented diet decreased, whereas a choline-deficient diet increased the intensity of immunohistochemical labeling for these proteins in El8 hippocampus. GAP43 and NSE were localized to peripheral nervous tissue but not hippocampus, indicating that the maturation of axons and neurite outgrowth in embryonic hippocampus were unaffected by the availability of choline in the diet. These data suggest that the availability of choline affects the differentiation of specific regions of developing hippocampus. 相似文献
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Effects of electrically induced fatigue on the twitch and tetanus of paralyzed soleus muscle in humans 总被引:1,自引:0,他引:1
Shields Richard K.; Law Laura Frey; Reiling Brenda; Sass Kelly; Wilwert Jason 《Journal of applied physiology》1997,82(5):1499-1507
Shields, Richard K., Laura Frey Law, Brenda Reiling, KellySass, and Jason Wilwert. Effects of electrically induced fatigueon the twitch and tetanus of paralyzed soleus muscle in humans.J. Appl. Physiol. 82(5):1499-1507, 1997.We analyzed the twitch and summated torque(tetanus) during repetitive activation and recovery of the human soleusmuscle in individuals with spinal cord injury. Thirteen individualswith complete paralysis (9 chronic, 4 acute) had the tibial nerveactivated every 1,500 ms with a 20-Hz train (7 stimuli) for 300 ms anda single pulse at 1,100 ms. The stimulation protocol lasted 3 min andincluded 120 twitches and 120 tetani. Minimal changes were found forthe acute group. The chronic group showed a significant reduction inthe torque and a significant slowing of the contractile speeds of boththe twitch and tetanus. The decrease in the peak twitch torque was significantly greater than the decrease in the peak tetanus torque early during the fatigue protocol for the chronic group. The twitch time to peak and half relaxation time were prolonged during fatigue, which was associated with improved fusion of the tetanus torque. At theend of the fatigue protocol, the decrease in the peak twitch torque wasnot significantly different from the decrease in the peak tetanustorque. After 5 min of rest, the contractile speeds recovered causingthe tetanus to become unfused, but the tetanus torque became lessdepressed than the twitch torque. The differential responses for thetwitch and the tetanus suggest an interplay between optimal fusioncreated from contractile speed slowing and excitation contractioncoupling compromise. These issues make the optimal design of functionalelectrical stimulation systems a formidable task. 相似文献
87.
Bates PJ Reddoch JF Hansakul P Arrow A Dale R Miller DM 《Analytical biochemistry》2002,307(2):235-243
Due to the instability of DNA oligonucleotides in biological solutions, antisense or antigene therapies aimed at modulation of specific gene expression will most likely require the use of oligonucleotides with modified backbones. Here, we examine the use of a surface plasmon resonance biosensor (BIAcore) to compare triplex-directed binding of modified oligonucleotides targeted to a region of the murine c-myc promoter. We describe optimization of experimental conditions to minimize nonspecific interactions between the oligonucleotides and the sensor chip surface, and the limitations imposed by certain backbones and sequence types. The abilities of pyrimidine oligonucleotides with various modified backbones to form specific triple helices with an immobilized hairpin duplex were readily determined using the biosensor. Modification of the third-strand oligonucleotide with RNA or 2(')-O-methyl RNA was found to enhance triplex formation, whereas phosphorothioate or phosphotriester substitutions abrogated it. A comparison of these results to DNase I footprinting experiments using the same oligonucleotides showed complete agreement between the two sets of data. 相似文献
88.
Javier Rasero Amy Isabella Sentis Fang-Cheng Yeh Timothy Verstynen 《PLoS computational biology》2021,17(3)
Variation in cognitive ability arises from subtle differences in underlying neural architecture. Understanding and predicting individual variability in cognition from the differences in brain networks requires harnessing the unique variance captured by different neuroimaging modalities. Here we adopted a multi-level machine learning approach that combines diffusion, functional, and structural MRI data from the Human Connectome Project (N = 1050) to provide unitary prediction models of various cognitive abilities: global cognitive function, fluid intelligence, crystallized intelligence, impulsivity, spatial orientation, verbal episodic memory and sustained attention. Out-of-sample predictions of each cognitive score were first generated using a sparsity-constrained principal component regression on individual neuroimaging modalities. These individual predictions were then aggregated and submitted to a LASSO estimator that removed redundant variability across channels. This stacked prediction led to a significant improvement in accuracy, relative to the best single modality predictions (approximately 1% to more than 3% boost in variance explained), across a majority of the cognitive abilities tested. Further analysis found that diffusion and brain surface properties contribute the most to the predictive power. Our findings establish a lower bound to predict individual differences in cognition using multiple neuroimaging measures of brain architecture, both structural and functional, quantify the relative predictive power of the different imaging modalities, and reveal how each modality provides unique and complementary information about individual differences in cognitive function. 相似文献
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90.
POL32 encodes a non-essential subunit of Polδ and plays a role in Polδ processivity and DNA repair. In order to understand how Pol32 is involved in these processes, we performed extensive genetic analysis and demonstrated that POL32 is required for Polζ-mediated translesion synthesis, but not for Polη-mediated activity. Unlike Polζ, inactivation of Pol32 does not result in decreased spontaneous mutagenesis, nor does it limit genome instability in the absence of the error-free postreplication repair pathway. In contrast, inactivation of Pol32 results in an increased rate of replication slippage and recombination. A genome-wide synthetic lethal screen revealed that in the absence of Pol32, homologous recombination repair and cell cycle checkpoints play crucial roles in maintaining cell survival and growth. These results are consistent with a model in which Pol32 functions as a coupling factor to facilitate a switch from replication to translesion synthesis when Polδ encounters replication-blocking lesions. When Pol32 is absent, the S-phase checkpoint complex Mrc1–Tof1 becomes crucial to stabilize the stalled replication fork and recruit Top3 and Sgs1. Lack of any of the above activities will cause double strand breaks at or near the replication fork that require recombination as well as Rad9 for cell survival. 相似文献