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Summary . We propose a fully inferential model-based approach to the problem of comparing the firing patterns of a neuron recorded under two distinct experimental conditions. The methodology is based on nonhomogeneous Poisson process models for the firing times of each condition with flexible nonparametric mixture prior models for the corresponding intensity functions. We demonstrate posterior inferences from a global analysis, which may be used to compare the two conditions over the entire experimental time window, as well as from a pointwise analysis at selected time points to detect local deviations of firing patterns from one condition to another. We apply our method on two neurons recorded from the primary motor cortex area of a monkey's brain while performing a sequence of reaching tasks. 相似文献
3.
Symeon M. Kyriakidis Theodore G. Sotiroudis Athanasios E. Evangelopoulos 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1988,972(3)
The interaction of rabbit muscle phosphorylase kinase (EC 2.7.1.38) with human erythrocyte membranes was investigated. It was found that at pH 7.0 the kinase binds to the inner face of the erythrocyte membrane (inside-out vesicles) and that this binding is Ca2+- and Mg2+-dependent. The sharpest increase in the binding reaction occurs at concentrations between 70 and 550 nM free Ca2+. Erythrocyte ghost or right-side out erythrocyte vesicles showed a significantly lower capacity to interact with phosphorylase kinase. Autophosphorylated phosphorylase kinase shows a similar Ca2+-dependent binding profile, while trypsin activation of the kinase and calmodulin decrease the original binding capacity by about 50%. Heparin (200 μg/ml) and high ionic strength (50 mM NaCl) almost completely blocks enzyme-membrane interaction; glycogen does not affect the interaction. 相似文献
4.
Basile Michaelidis Athanasios Papadopoulos Isidoros Beis 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,160(2):201-206
Summary The kinetic properties of PK and PFK were studied in aerobic versus 12-hours anoxic marine worms Hedistae(=Nereis) diversicolor and Diopatra neapolitana and earth worms Allolobophora calliginosa and Eisenia foetida. The total glycogen phosphorylase (a+b) activity and the percentage of active a form were also measured in the marine and earth worms under the same conditions. Anoxia exposure did not result in any significant changes of kinetic parameters of PK and total activities of glycogen phosphorylase from marine worms, but it altered the kinetic characteristics of PFK from H. diversicolor. Chromatographical studies showed that PK from both aerobic and anoxic marine worms is eluted from DEAE-cellulose as a single peak at 50 mM KCl. In contrast to marine worms, however, anoxia caused a marked change in kinetic properties of PK from both earth worms, resulting in a reduction of enzyme affinity for its substrate PEP. In addition, the enzyme existed in both earth worms in two distinct variants eluted from DEAE-cellulose column as peak I and peak II at 50 mM and 150 mM KCl, respectively. The ratio of enzyme units (peak I/peak II) was reduced significantly after 12 h of anoxia, indicating that these two peaks are interconvertible. Anoxia also caused a reduction of total glycogen phosphorylase activity in E. foetida and lowered the percentage of active a form of the enzyme by approximately 50% in both earth worms. Kinetic properties of PFK from both earth worms were not significantly affected by anoxia. However, their low Ka values for F-2,6-P2 imply that this effector may play an important role in PFK control in earth worms under anoxia.Abbreviations
F6P
fructose-6-phosphate
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FBP
fructose-1,6-bisphosphate
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F-2,6-P
fructose-2,6-bisphosphate
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PEP
phosphoenoylpruvate
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PFK
6-phosphofructo-1-kinase (E.C.2.7.1.11)
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PK
pyruvate kinase (E.C.2.7.1.40)
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Pi
inorganic phosphate
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PMSF
phenyl methylsulfonyl fluoride 相似文献
5.
Ilias Tirodimos Inge-M. Pretorius-Güth Ursula Priefer Athanasios Tsaftaris Asterios S. Tsiftsoglou 《Applied microbiology and biotechnology》1993,38(4):526-530
In order to assess the risk associated with the deliberate release of genetically engineered microorganisms (GEMs) into the agricultural environment, the transfer of plasmids between bacterial strains was investigated under laboratory conditions. Genetically modified Rhizobium leguminosarum and Agrobacterium tumefaciens strains carrying the gentamycin acetyltransferase resistance gene (aacC1) on various plasmids were investigated for their ability to transfer the aacC1 gene to their wild-type (w.t.) counterparts, as well as to Pseudomonas syringae. Conjugation experiments between the various strains, were carried out after the relevant characteristics and conditions for selective growth of each bacterial strain had been ascertained. After conjugations on filters had been completed, the putative transconjugants were grown in media containing antibiotics and assessed for the presence of aacC1 gene by: (a) DNA plasmid profile; (b) expression of AAC(3)-I enzyme activity; (c) colony hybridization using a 32P-labelled DNA probe complementary to the aacC1 gene. The results obtained indicate that transfer of the aacC1 gene from genetically modified strains of R. leguminosarum into a plasmid-free strain of A. tumefaciens occurred via self-transmissible plasmids. Alternatively, genetically modified A. tumefaciens bearing the aacC1 gene on plasmids acquired from R. leguminosarum strains, transferred it ineffectively to a hardly detectable frequency. No transfer of the aacC1 gene from genetically modified R. leguminosarum or A. tumefaciens strains into P. syringae has been observed. These data indicate that in the absence of the RP4 element, genetically modified A. tumefaciens is not able to efficiently transfer aacC1 into w.t. R. leguminosarum and P. syringae.
Correspondence to: A. S. Tsiftsoglou 相似文献
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Male and female D. oleae have similar powers of acclimation when exposed to low temperatures. Their torpor thresholds depend upon the temperature to which they have been acclimatised. During slow cooling (i.e. less than 1°C per min) they are capable of some rapid acclimation which enables them to lower their torpor threshold by almost 1°C degree, as compared with when they are chilled quickly. After abrupt transfer from 25°C to a different temperature, acclimation takes some time to be accomplished. At 15°C and above it occurs within 10 days but at temperatures below this, progressive acclimation lowers the torpor thresholds to the very low levels typical of flies overwintering under natural conditions. During this long term acclimation torpor thresholds may change by almost 0.5°C per 1°C change of acclimation temperature.No differences were observed in the ability of either flies from northern and southern Greece, or normal and γ-irradiated laboratory reared flies to acclimate to winter conditions in the field. In all cases, torpor thresholds were progressively lowered in advance of the decline in weekly minimum temperatures. 相似文献
8.
The hypothermia that follows induction of cerebral infraction in gerbils can be attenuated by drugs which reduce the interactions between endogenous brain catecholamines and postsynaptic receptors. This observation is compatible with the hypothesis that stroke-induced hypothermia is mediated, in part, by the release of catecholamines from ischemic neurons. 相似文献
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10.
The oleaginous yeast Yarrowia lipolytica is known to inhabit various lipid-containing environments. One of the most striking features in this yeast is the presence of several multigene families involved in the metabolic pathways of hydrophobic substrate utilization. The complexity and the multiplicity of these genes give Y. lipolytica a wide capability range towards hydrophobic substrate (HS) utilization and storage. The combination of the increasing knowledge of this yeast's metabolism and the development of more efficient genetic tools is offering new perspectives in using Y. lipolytica as a model organism to study the mechanisms involved in lipid metabolism associated to fat uptake, storage, deposition, mobilization and regulation. Nutrient status and culture conditions seem to play a major role in obesity. 相似文献