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141.
Patterned spontaneous activity in the developing retina is necessary to drive synaptic refinement in the lateral geniculate nucleus (LGN). Using perforated patch recordings from neurons in LGN slices during the period of eye segregation, we examine how such burst-based activity can instruct this refinement. Retinogeniculate synapses have a novel learning rule that depends on the latencies between pre- and postsynaptic bursts on the order of one second: coincident bursts produce long-lasting synaptic enhancement, whereas non-overlapping bursts produce mild synaptic weakening. It is consistent with “Hebbian” development thought to exist at this synapse, and we demonstrate computationally that such a rule can robustly use retinal waves to drive eye segregation and retinotopic refinement. Thus, by measuring plasticity induced by natural activity patterns, synaptic learning rules can be linked directly to their larger role in instructing the patterning of neural connectivity. 相似文献
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143.
Human global ischaemia was simulated in adult rats by inducing 20 min brain ischaemia and 60 min post-ischaemic recirculation.
Immunohistochemical expression of MMP-9, TIMP-3, Bax and Bcl-2, and DNA fragmentation (with the TUNEL reaction) were investigated.
The morphological data showed different neuronal responses in the hippocampus compared with the cerebral and cerebellar cortices.
MMP-9 immunoreactivity was different in the hippocampus, particularly in dentate gyrus and the CA1 region, compared with these
cortices. Negative TIMP-3 staining in ischaemic hippocampal neurons may indicate a loss of its inhibitory activity on MMP-9
that could enhance cell death. Bcl-2 down regulation, Bax positivity and TUNEL+ type II cells in the dentate gyrus granular
layer could be responsible for induction of apoptotic death in CA1 hippocampal pyramidal cells via loss of fibre input. Results
suggest differential behaviours of neural cells after 60 min reperfusion. 相似文献
144.
Lucarini Elena Micheli Laura Di Cesare Mannelli Lorenzo Ghelardini Carla 《Phytochemistry Reviews》2022,21(2):647-665
Phytochemistry Reviews - Investigation into glucosinolates (GLs) therapeutic effects boasts a long history, which began with the evidence that their hydrolysis-derived isothiocyanates (ITCs) could... 相似文献
145.
Clementine Lasne Belinda Van Heerwaarden Carla M. Sgr Tim Connallon 《Evolution; international journal of organic evolution》2019,73(2):262-277
During local adaptation with gene flow, some regions of the genome are inherently more responsive to selection than others. Recent theory predicts that X‐linked genes should disproportionately contribute to local adaptation relative to other genomic regions, yet this prediction remains to be tested. We carried out a multigeneration crossing scheme, using two cline‐end populations of Drosophila melanogaster, to estimate the relative contributions of the X chromosome, autosomes, and mitochondrial genome to divergence in four traits involved in local adaptation (wing size, resistance to heat, desiccation, and starvation stresses). We found that the mitochondrial genome and autosomes contributed significantly to clinal divergence in three of the four traits. In contrast, the X made no significant contribution to divergence in these traits. Given the small size of the mitochondrial genome, our results indicate that it plays a surprisingly large role in clinal adaptation. In contrast, the X, which represents roughly 20% of the Drosophila genome, contributes negligibly—a pattern that conflicts with theoretical predictions. These patterns reinforce recent work implying a central role of mitochondria in climatic adaptation, and suggest that different genomic regions may play fundamentally different roles in processes of divergence with gene flow. 相似文献
146.
Atkinson Carla L. Alexiades Alexander V. MacNeill Keeley L. Encalada Andrea C. Thomas Steve A. Flecker Alexander S. 《Hydrobiologia》2019,838(1):13-28
Hydrobiologia - High- to mid-elevation streams are often oligotrophic, but harbor diverse groups of aquatic animals that can satisfy a substantial proportion of nutrient demand. Therefore, we... 相似文献
147.
Carla Frare Mackenzie E. Jenkins Kelsey M. McClure Kelly L. Drew 《Journal of neurochemistry》2019,151(3):316-335
148.
149.
Angela Lombardi Michele Saviano Flavia Nastri Ornella Maglio Marco Mazzeo Carla Isernia Livio Paolillo Vincenzo Pavone 《Biopolymers》1996,38(6):693-703
In the present paper we describe the solution nmr structural analysis and restrained molecular dynamic simulation of the cyclic pentapeptide cyclo-(Pro-Phe-Phe-β-Ala-β-Ala). The conformational analysis carried out in CD3CN and dimethylsulfoxide (DMSO) solutions by nmr spectroscopy was based on interproton distances derived from rotating frame nuclear Overhauser effect spectroscopy spectra and homonuclear coupling constants. A restrained molecular dynamic simulation in vacuo was also performed to build refined molecular models. The molecule is present in both solvent systems as two slowly interconverting conformers, characterized by a cis-trans isomerism around the β-Ala5-Pro1 peptide bond. In CD3CN solution, the conformer with a cis peptide bond is quite similar to that observed in the solid state, while the conformer containing all trans peptide bonds is characterized by an intramolecular hydrogen bond stabilizing a C10- and a C13-ring structure. In DMSO solution, the trans isomer is partly similar to that observed in CD3CN solution while the cis isomer is different from that observed in the solid state. The effect of the solvent in stabilizing different conformations was also investigated in DMSO-CD3CN solvent mixtures. © 1996 John Wiley & Sons, Inc. 相似文献
150.
M. Novella Romanelli Alessandro Bartolini Carlo Bertucci Silvia Dei Carla Ghelardini M. Grazia Giovannini Fulvio Gualtieri Giancarlo Pepeu Serena Scapecchi Elisabetta Teodori 《Chirality》1996,8(3):225-233
The enantiomers of two α-tropanyl esters, SM21 (1) and PG9 (2), derived from (+)-R-hyoscyamine, that act by increasing the central cholinergic tone, were obtained by esterification after resolution of the corresponding racemic acids [(−)-S-1, (−)-R-2 and (+)-S-2] and by stereospecific synthesis [(+)-R-1]. Their analgesic and cognition-enhancing activities were tested in mice and their ACh-releasing properties determined on rat parietal cortex. These compounds show enantioselectivity in analgesic and cognition-enhancing tests on mice, the eutomers being the isomers which possess the same spatial arrangement of the groups on the chiral atom as (+)-R hyoscyamine [(+)-R-SM21, (+)-S-PG9]. The ACh-releasing effect of the enantiomers of SM21 in rats is in agreement with the results in mice, while PG9 enantiomers do not show any appreciable enantioselectivity in this test. On the basis of the different effects of the 5-HT4 antagonist SDZ 205557 on analgesia induced by the enantiomers of 1 and 2 and by (+)-R-hyoscyamine and the α-tropanyl ester of 2-phenylpropionic acid 3, a mechanism of action is proposed for this class of compounds. © 1996 Wiley-Liss, Inc. 相似文献