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51.
In eukaryotes, cellular energy in the form of ATP is produced in the cytosol via glycolysis or in the mitochondria via oxidative
phosphorylation and, in photosynthetic organisms, in the chloroplast via photophosphorylation. Transport of adenine nucleotides
among cell compartments is essential and is performed mainly by members of the mitochondrial carrier family, among which the
ADP/ATP carriers are the best known. This work reviews the carriers that transport adenine nucleotides into the organelles
of eukaryotic cells together with their possible functions. We focus on novel mechanisms of adenine nucleotide transport,
including mitochondrial carriers found in organelles such as peroxisomes, plastids, or endoplasmic reticulum and also mitochondrial
carriers found in the mitochondrial remnants of many eukaryotic parasites of interest. The extensive repertoire of adenine
nucleotide carriers highlights an amazing variety of new possible functions of adenine nucleotide transport across eukaryotic
organelles. 相似文献
52.
岳崇兴 《河南师范大学学报(自然科学版)》1995,(1)
本文用TC(Technicolor)模型,解释了L3L ̄+L ̄-γγ事例,具体分析发现四个L3事例可以由过程z→ρ°ρ°→L ̄+L ̄-P°(γγ)产生。 相似文献
53.
Zusammenfassung Es wird gezeigt, dass beim Sheehan-Syndrom, trotz herabgesetzter Kalorienzufuhr, im Urin die fettmobilisierende Substanz (Chalmers)
fehlt. Bei Akromegalie, teilweise auch beim Diabetes erwies sich der Urinextrakt bei normaler Di?t als aktiv. Eine gleichzeitige
Insulinzufuhr verhinderte die fettmobilisierende Wirkung.
相似文献
54.
The novel Cer-like protein Caronte mediates the establishment of embryonic left-right asymmetry. 总被引:1,自引:0,他引:1
C Rodríguez Esteban J Capdevila A N Economides J Pascual A Ortiz J C Izpisúa Belmonte 《Nature》1999,401(6750):243-251
In the chick embryo, left-right asymmetric patterns of gene expression in the lateral plate mesoderm are initiated by signals located in and around Hensen's node. Here we show that Caronte (Car), a secreted protein encoded by a member of the Cerberus/Dan gene family, mediates the Sonic hedgehog (Shh)-dependent induction of left-specific genes in the lateral plate mesoderm. Car is induced by Shh and repressed by fibroblast growth factor-8 (FGF-8). Car activates the expression of Nodal by antagonizing a repressive activity of bone morphogenic proteins (BMPs). Our results define a complex network of antagonistic molecular interactions between Activin, FGF-8, Lefty-1, Nodal, BMPs and Car that cooperate to control left-right asymmetry in the chick embryo. 相似文献
55.
Ramsés Fuenmayor 《Systemic Practice and Action Research》1990,3(6):525-544
This paper is the first in a trilogy which intends to discuss the notion of critique within two different contexts: Modern Western Philosophy and Contemporary Systems Thinking. This first paper presents a phenomenological inquiry into the concept of “critique.” The result of the inquiry is a model of the possibilities ofcritique which is used to interpret four “moments” of critique in Modern Western Philosophy. 相似文献
56.
Pitx2 regulates lung asymmetry, cardiac positioning and pituitary and tooth morphogenesis. 总被引:27,自引:0,他引:27
C R Lin C Kioussi S O'Connell P Briata D Szeto F Liu J C Izpisúa-Belmonte M G Rosenfeld 《Nature》1999,401(6750):279-282
57.
Subthreshold Na+-dependent theta-like rhythmicity in stellate cells of entorhinal cortex layer II 总被引:13,自引:0,他引:13
The oscillation of membrane potential in mammalian central neurons is of interest because it relates to the role of oscillations in brain function. It has been proposed that the entorhinal cortex (EC), particularly the stellate cells of layer II (ECIIscs), plays an important part in the genesis of the theta rhythm. These neurons occupy a key position in the neocortex-hippocampus-neocortex circuit, a crucial crossroad in memory functions. Neuronal oscillations typically rely on the activation of voltage-dependent Ca2+ conductances and the Ca2+ -dependent K+ conductance that usually follows, as seen in other limbic subcortical structures generating theta rhythmicity. Here we report, however, that similar oscillations are generated in ECIIscs by a Na+ conductance. The finding of a subthreshold, voltage-gated, Na+ -dependent rhythmic membrane oscillation in mammalian neurons indicates that rhythmicity in heterogeneous neuronal networks may be supported by different sets of intrinsic ionic mechanisms in each of the neuronal elements involved. 相似文献
58.
Much business cycle research is based on an assumption of symmetric cycles, though it is frequently argued that the downturns are steeper and more short-lived than the upturns; implying cyclical asymmetries. A new class of nonlinear autoregressive-asymmetric moving average models is introduced. These models are able to deal with symmetric as well as asymmetric phenomena. A likelihood estimation procedure and a Wald test statistic for symmetry are presented. Evidence of asymmetry is found in US real GNP growth rates. 相似文献
59.
The ability of dog renal cortex slices to accumulate beta-methyl-glucoside or glycine is enhanced by the flavonoid (+)-catechin at a concentration of 3.5 mM. This stimulatory effect is apparently due to a decreased rate of efflux of either substrate. On the other hand, the uptake of p-amino-hippuric acid and N1-methyl-nicotinamide is inhibited by (+)-catechin. The drug at the same concentration is without action on amino-acid transport by guinea-pig intestine in vitro. 相似文献
60.
Summary The disappearance of thrombin—formed in the blood, or added to serum-follows a manomolecular reaction-type. Heparin increases the reaction-velocity of this thrombin-inactivating process.Our investigation established that toluidine blue or kinase, which, according to the literature, bind heparin, strongly reduce the speed of thrombin-inactivation too. Therefore the heparin-binding capacity of these substances is also manifested in the decrease of thrombin-inactivation. 相似文献