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121.
Turner JM Körtner G Warnecke L Geiser F 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2012,162(3):274-280
Torpor is usually associated with low ambient temperatures (T(a)) in winter, but in some species it is also used in summer, often in response to limited food availability. Since the seasonal expression of torpor of both placental and marsupial hibernators in the wild is poorly documented by quantitative data, we investigated torpor and activity patterns of the eastern pygmy-possum Cercartetus nanus (17.4 g) over two seasons. We used radio telemetry to track animals during winter (n=4) and summer (n=5) in a warm-temperate habitat and found that torpor was used in both seasons. In winter all animals entered periods of short-term hibernation (from 5 to 20 days) containing individual torpor bouts of up to 5.9 days. In summer, torpor bouts were always <1 day in duration, only used by males and were not related to daily mean T(a). Pygmy-possums entered torpor at night as T(a) cooled, and rewarmed during the afternoon as T(a) increased. Individuals interspersed torpor bouts with nocturnal activity and the percentage of the night animals were active was the same in summer and winter. Our study provides the first information on torpor patterns in free-ranging C. nanus, and shows that the use of torpor throughout the year is important for energy management in this species. 相似文献
122.
The electrophysiological characteristics of frequency potentiation and habituation were investigated in two afferent systems of the in vitro hippocampal slice preparation. Low frequency stimulation (1 Hz) of the Schaffer collateral - commissural (Sch-comm) fibers results in a short-term potentiation of the amplitude and rate of rise of the EPSP and population spike responses recorded in the CA1 region. In contrast, 1-Hz stimulation of the perforant path (PP) evokes a short-term, habituation-like depression of the dentate granule cell EPSP and population spike. An inverse relationship was observed between stimulus intensity and the magnitude of frequency potentiation or habituation. Changes in afferent fiber volleys or general excitability of postsynaptic membranes did not contribute significantly to the development of either of these forms of short-term plasticity. Perfusion with a medium containing a high calcium - low magnesium concentration (4 mM Ca+2 and 1 mM Mg+2) produced a differential effect on CA1 and dentate evoked potentials. Following a 20-min exposure to this medium, the amplitude of CA1 potentials was increased while dentate responses were decreased. Frequency potentiation of CA1 responses and habituation of dentate responses were depressed or eliminated by the high calcium medium. The opposing influence of extracellular calcium on CA1 and dentate evoked potentials indicates a fundamental difference in the process of transmitter release in these systems, a characteristic that may contribute to the production of frequency potentiation and habituation. 相似文献
123.
Young In Sohn Nathanael J. Lee Andrew Chung Juan M. Saavedra R. Scott Turner Daniel T.S. Pak Hyang-Sook Hoe 《Biochemical and biophysical research communications》2013
Recent studies demonstrated that the antihypertensive drug Valsartan improved spatial and episodic memory in mouse models of Alzheimer’s Disease (AD) and human subjects with hypertension. However, the molecular mechanism by which Valsartan can regulate cognitive function is still unknown. Here, we investigated the effect of Valsartan on dendritic spine formation in primary hippocampal neurons, which is correlated with learning and memory. Interestingly, we found that Valsartan promotes spinogenesis in developing and mature neurons. In addition, we found that Valsartan increases the puncta number of PSD-95 and trends toward an increase in the puncta number of synaptophysin. Moreover, Valsartan increased the cell surface levels of AMPA receptors and selectively altered the levels of spinogenesis-related proteins, including CaMKIIα and phospho-CDK5. These data suggest that Valsartan may promote spinogenesis by enhancing AMPA receptor trafficking and synaptic plasticity signaling. 相似文献
124.
The Impact of Adult Vitamin D Deficiency on Behaviour and Brain Function in Male Sprague-Dawley Rats
Jacqueline H. Byrne Meggie Voogt Karly M. Turner Darryl W. Eyles John J. McGrath Thomas H. J. Burne 《PloS one》2013,8(8)
Background
Vitamin D deficiency is common in the adult population, and this has been linked to depression and cognitive outcomes in clinical populations. The aim of this study was to investigate the effects of adult vitamin D (AVD) deficiency on behavioural tasks of relevance to neuropsychiatric disorders in male Sprague-Dawley rats.Methods
Ten-week old male Sprague-Dawley rats were fed a control or vitamin D deficient diet for 6 weeks prior to, and during behavioural testing. We first examined a range of behavioural domains including locomotion, exploration, anxiety, social behaviour, learned helplessness, sensorimotor gating, and nociception. We then assessed locomotor response to the psychomimetic drugs, amphetamine and MK-801. Attention and vigilance were assessed using the 5 choice serial reaction time task (5C-SRT) and the 5 choice continuous performance task (5C-CPT) and, in a separate cohort, working memory was assessed using the delay match to sample (DMTS) task. We also examined excitatory and inhibitory neurotransmitters in prefrontal cortex and striatum.Results
AVD-deficient rats were deficient in vitamin D3 (<10 nM) and had normal calcium and phosphate levels after 8–10 weeks on the diet. Overall, AVD deficiency was not associated with an altered phenotype across the range of behavioural domains tested. On the 5C-SRT AVD-deficient rats made more premature responses and more head entries during longer inter-trial intervals (ITI) than control rats. On the 5C-CPT AVD-deficient rats took longer to make false alarm (FA) responses than control rats. AVD-deficient rats had increases in baseline GABA levels and the ratio of DOPAC/HVA within the striatum.Conclusions
AVD-deficient rats exhibited no major impairments in any of the behavioural domains tested. Impairments in premature responses in AVD-deficient rats may indicate that these animals have specific alterations in striatal systems governing compulsive or reward-seeking behaviour. 相似文献125.
Olivier Maurin Artemis Anest Sidonie Bellot Edward Biffin Grace Brewer Tristan Charles-Dominique Robyn S. Cowan Steven Dodsworth Niroshini Epitawalage Berta Gallego Augusto Giaretta Renato Goldenberg Deise J.P. Gonçalves Shirley Graham Peter Hoch Fiorella Mazine Yee Wen Low Catherine McGinnie Fabián A. Michelangeli Sarah Morris Darin S. Penneys Oscar Alejandro Pérez Escobar Yohan Pillon Lisa Pokorny Gustavo Shimizu Vanessa G. Staggemeier Andrew H. Thornhill Kyle W. Tomlinson Ian M. Turner Thais Vasconcelos Peter G. Wilson Alexandre R. Zuntini William J. Baker Félix Forest Eve Lucas 《American journal of botany》2021,108(7):1087-1111
126.
The frequency and form of the middle trigonid crest (MTC) in lower permanent molars is reported for 1,131 dental casts of Bushman (San), Bantu, Solomons, Hawaiians, Pima, Eskimo, Navajo, Chinese, and American whites. The MTC occurs most often on the first molar. We found very little intra-trait variation, so observations were scored on a present-absent basis. The MTC is most frequent in the African samples and rare in those of the other populations. Two reference plaques can be obtained to add to the existing series in the ASU dental anthropology system. © 1993 Wiley-Liss, Inc. 相似文献
127.
Induction of ethanolamine ammonia-lyase formation in Escherichia coli required both the ethanolamine and vitamin B12, and was gratuitous during growth on glycerol. Ethanolamine analogues inhibited enzyme activity and inhibited growth with ethanolamine as the the nitrogen source, but did not act as inducers. Enzyme formation was more rapid when ethanolamine was added to cultures containing vitamin B12 rather than the reverse. Enzyme formation was subject to catabolic repression, glucose and acetate being particularly effective. Chloramphenicol, I-aminopropan 2-01 and 1,3-diaminopropan-2-01 prevented enzyme induction. Ethanolamine ammonia-lyase, resolved from its cobamide coenzyme, was purified 35-fold. The apoenzyme was stable for several days in the presence of ethanolamine, dithiothreitol, glycerol and K+ ions. Enzyme formation therefore requires both substrate and cobamide coenzyme to be present simultaneously as inducers. 相似文献
128.
The membrane-bound form of mammalian aminopeptidase P (AP-P; EC 3.4. 11.9) is a mono-zinc-containing enzyme that lacks any of the typical metal binding motifs found in other zinc metalloproteases. To identify residues involved in metal binding and catalysis, sequence and structural information was used to align the sequence of porcine membrane-bound AP-P with other members of the peptidase clan MG, including Escherichia coli AP-P and methionyl aminopeptidases. Residues predicted to be critical for activity were mutated and the resultant proteins were expressed in COS-1 cells. Immunoelectrophoretic blot analysis was used to compare the levels of expression of the mutant proteins, and their ability to hydrolyze bradykinin and Gly-Pro-hydroxyPro was assessed. Asp449, Asp460, His523, Glu554, and Glu568 are predicted to serve as metal ion ligands in the active site, and mutagenesis of these residues resulted in fully glycosylated proteins that were catalytically inactive. Mutation of His429 and His532 also resulted in catalytically inactive proteins, and these residues, by analogy with E. coli AP-P, are likely to play a role in shuttling protons during catalysis. These studies indicate that mammalian membrane-bound AP-P has an active-site configuration similar to that of other members of the peptidase clan MG, which is compatible with either a dual metal ion model or a single metal ion in the active site. The latter model is consistent, however, with the known metal stoichiometry of both the membrane-bound and cytosolic forms of AP-P and with a recently proposed model for methionyl aminopeptidase. 相似文献
129.
The NC1 domain of type IV collagen promotes axonal growth in sympathetic neurons through interaction with the alpha 1 beta 1 integrin 总被引:3,自引:2,他引:3 下载免费PDF全文
P J Lein D Higgins D C Turner L A Flier V P Terranova 《The Journal of cell biology》1991,113(2):417-428
We have examined the effects of collagen IV on the morphological development of embryonic rat sympathetic neurons in vitro. In short-term (less than or equal to 24 h) culture, collagen IV accelerated process outgrowth, causing increases in the number of neurites and total neuritic length. Analysis of proteolytic fragments of collagen IV indicated that the NC1 domain was nearly as active as the intact molecule in stimulating process outgrowth; in contrast, the 7S domain and triple helix-rich fragments of collagen IV were inactive. Moreover, anti-NC1 antiserum inhibited neuritic outgrowth on collagen IV by 79%. In long-term (up to 28 d) cultures, neurons chronically exposed to collagen IV maintained a single axon but failed to form dendrites. Thus, the NC1 domain of collagen IV can alter neuronal development by selectively stimulating axonal growth. Comparison of collagen IV's effects to those of laminin revealed that these molecules exert quantitatively different effects on the rate of initial axon growth and the number of axons extended by sympathetic neurons. Moreover, neuritic outgrowth on collagen IV, but not laminin, was blocked by cycloheximide. We also observed differences in the receptors mediating the neurite-promoting activity of these proteins. Two different antisera that recognize beta 1 integrins each blocked neuritic outgrowth on both collagen IV and laminin; however, an mAb (3A3) specific for the alpha 1 beta 1 integrin inhibited collagen IV but not laminin-induced process growth in cultures of both sympathetic and dorsal root neurons. These data suggest that immunologically distinct integrins mediate the response of peripheral neurons to collagen IV and laminin. 相似文献
130.
A set of nearest neighbor parameters for predicting the enthalpy change of RNA secondary structure formation 总被引:2,自引:1,他引:2 下载免费PDF全文
A complete set of nearest neighbor parameters to predict the enthalpy change of RNA secondary structure formation was derived. These parameters can be used with available free energy nearest neighbor parameters to extend the secondary structure prediction of RNA sequences to temperatures other than 37°C. The parameters were tested by predicting the secondary structures of sequences with known secondary structure that are from organisms with known optimal growth temperatures. Compared with the previous set of enthalpy nearest neighbor parameters, the sensitivity of base pair prediction improved from 65.2 to 68.9% at optimal growth temperatures ranging from 10 to 60°C. Base pair probabilities were predicted with a partition function and the positive predictive value of structure prediction is 90.4% when considering the base pairs in the lowest free energy structure with pairing probability of 0.99 or above. Moreover, a strong correlation is found between the predicted melting temperatures of RNA sequences and the optimal growth temperatures of the host organism. This indicates that organisms that live at higher temperatures have evolved RNA sequences with higher melting temperatures. 相似文献