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1.
Glutamate is the main excitatory amino acid, but its presence in the extracellular milieu has deleterious consequences. It
may induce excitotoxicity and also compete with cystine for the use of the cystine–glutamate exchanger, blocking glutathione
neosynthesis and inducing an oxidative stress-induced cell death. Both mechanisms are critical in the brain where up to 20%
of total body oxygen consumption occurs. In normal conditions, the astrocytes ensure that extracellular concentration of glutamate
is kept in the micromolar range, thanks to their coexpression of high-affinity glutamate transporters (EAATs) and glutamine
synthetase (GS). Their protective function is nevertheless sensitive to situations such as oxidative stress or inflammatory
processes. On the other hand, macrophages and microglia do not express EAATs and GS in physiological conditions and are the
principal effector cells of brain inflammation. Since the late 1990s, a number of studies have now shown that both microglia
and macrophages display inducible EAAT and GS expression, but the precise significance of this still remains poorly understood.
Brain macrophages and microglia are sister cells but yet display differences. Both are highly sensitive to their microenvironment
and can perform a variety of functions that may oppose each other. However, in the very particular environment of the healthy
brain, they are maintained in a repressed state. The aim of this review is to present the current state of knowledge on brain
macrophages and microglial cells activation, in order to help clarify their role in the regulation of glutamate under pathological
conditions as well as its outcome. 相似文献
2.
Soil and climate are major constituents of the French notion of Terroir. This concept implies that there is a strong relationship
between the composition of the grape, the characteristics of the wine and the territory of production. To study this link,
a new method of characterization of the Terroir, including geological and pedological factors, was investigated. It uses a
field model based on depth and clay content of soil, together with the degree of weathering of the parent rock. Consequently,
for every type of parent rock belonging to a given geologic stage, there are a series of soils that show different stages
of pedological evolution. According to the model, three kinds of soils are distinguished with regards to the weathering intensity
of the parent rock, that are named weakly weathered rock (WWR), moderately weathered rock (MWR) and strongly weathered rock
(SWR). By hypothesis, each soil type is considered as a homogeneous unit for vine production from the viewpoint of ecophysiological
factors. Each terroir unit defined by this method is called a Basic Terroir Unit (BTU). To validate this hypothesis, experimental
plots planted with Chenin and Cabernet Franc vines were studied over three consecutive seasons (2000–2002), in the Anjou vineyard
(Loire Valley – France). The major BTUs developed on the two most important geological systems of Anjou (Brioverian and Ordovician–Devonian),
were studied. Results showed that the berries of vines cultivated in WWR were significantly smaller, richer in sugars and
anthocyanins and had a Total Phenolic Index higher than those of the vines cultivated in SWR. They also had a lower titratable
acidity. Cabernet Franc vines cultivated in MWR had berries with sugar and anthocyanin contents but also total phenolics very
close to those of WWR. With Chenin vines there was a good relationship between the global pool of free aromas of berries and
the BTU type. The study showed significant relationships between the quality of grapes and the measured values of several
ecophysiological variables such as the water supply regime or the timing of budburst. 相似文献
3.
4.
Marie-Hélène Avelange Jean M. Thiéry Frédéric Sarrey Pierre Gans Fabrice Rébeillé 《Planta》1991,183(2):150-157
In order to estimate photosynthetic and respiratory rates in illuminated photoautotrophic cells of carnation (Dianthus caryophyllus L.), simultaneous measurements of CO2 and O2 gas exchange were performed using 18O2, 13CO2 and a mass-spectrometry technique. This method allowed the determination, and thus the comparison, of unidirectional fluxes of O2 and CO2. In optimum photosynthetic conditions (i.e. in the presence of high light and a saturating level of CO2), the rate of CO2 influx represented 75±5% of the rate of gross O2 evolution. After a dark-to-light transition, the rate of CO2 efflux was inhibited by 50% whereas the O2-uptake rate was little affected. The effect of a recycling of respiratory CO2 through photosynthesis on the exchange of CO2 gas was investigated using a mathematical model. The confliction of the experimental data with the simulated gas-exchange rates strongly supported the view that CO2 recycling was a minor event in these cells and could not be responsible for the observed inhibition of CO2 efflux. On the basis of this assumption it was concluded that illumination of carnation cells resulted in a decrease of substrate decarboxylations, and that CO2 efflux and O2 uptake were not as tightly coupled in the light as in the dark. Furthermore, it could be calculated from the rate of gross photosynthesis that the chloroplastic electron-transport chain produced enough ATP in the light to account for the measured CO2-uptake rate without involving cyclic transfer of electrons around PS I or mitochondrial supplementation.Abbreviations Chl
chlorophyll
- Kd
permeability coefficient
The authors thank Drs A. Vermeglio and P. Thibault, Dépt. de Biologie, CEN-Cadarache, St. Paul Lez Durance, France, for helpful discussions. 相似文献
5.
6.
Use of Genetic and Physical Mapping to Locate the Spinal Muscular Atrophy Locus between Two New Highly Polymorphic DNA Markers 总被引:9,自引:2,他引:7 下载免费PDF全文
Olivier Clermont Philippe Burlet Lydie Burglen Suzie Lefebvre Fabrice Pascal John McPherson John J. Wasmuth Daniel Cohen Denis Le Paslier Jean Weissenbach Mark Lathrop Arnold Munnich Judith Melki 《American journal of human genetics》1994,54(4):687-694
The gene for autosomal recessive forms of spinal muscular atrophy (SMA) has recently been mapped to chromosome 5ql3, within a 4-cM region between the blocks D5S465/D5S125 and MAP-1B/D5S112. We identified two new highly polymorphic microsatellite DNA markers—namely, AFM265wf5 (D5S629) and AFM281yh9 (D5S637)—which are the closest markers to the SMA locus. Multilocus analysis by the location-score method was used to establish the best estimate of the SMA gene location. Our data suggest that the most likely location for SMA is between locus D5S629 and the block D5S637/D5S351/MAP-1B/D5S112/D5S357. Genetic analysis of inbred SMA families, based on homozygosity by descent and physical mapping using mega-YACs, gave additional information for the loci order as follows: cen–D5S6–D5S125/D5S465–D5S435–D5S629–SMA–D5S637–D5S351–MAP–1B/D5S112–D5S357–D5S39–tel. These data give the direction for bidirectional walking in order to clone this interval and isolate the SMA gene. 相似文献
7.
Stimulation of the Cyclic GMP Pathway by NO Induces Expression of the Immediate Early Genes c-fos and junB in PC12 Cells 总被引:7,自引:2,他引:5
Christelle Haby Fabrice Lisovoski Dominique Aunis Jean Zwiller 《Journal of neurochemistry》1994,62(2):496-501
Abstract: Stimulation of several second messenger pathways induces the expression of immediate early genes such as c- fos , c- jun , junB , and junD , but little is known about their induction via the stimulation of the cyclic GMP pathway. Here we looked at the expression of early genes in pheochromocytoma PC12 cells after activation of cytosolic guanylate cyclase by sodium nitroprusside. This compound spontaneously releases NO, a molecule known to be involved in cell communication. We found that expression of c- fos and junB but not of c- jun or junD is increased upon activation of cyclic GMP pathway. c- fos mRNA expression was the most activated (fourfold at 30 min), whereas junB response was more modest (2.2-fold activation at 60 min). Nuclear extracts of stimulated cells show increased binding capacity to the AP1 binding site consistent with the dose-response curve. The activating effect of nitroprusside could be reproduced by dipyridamole, a selective cyclic GMP phosphodiesterase inhibitor and by 8- p -chlorophenylthio-cyclic GMP, a permeant selective cyclic GMP-dependent protein kinase activator, and abolished by KT5823, an inhibitor of that kinase. The results show that NO promotes early gene activation and AP1 binding enhancement through the stimulation of the cyclic GMP pathway. 相似文献
8.
Jérémy Gauthier Joana Meier Fabrice Legeai Melanie McClure Annabel Whibley Anthony Bretaudeau Hélène Boulain Hugues Parrinello Sam T. Mugford Richard Durbin Chenxi Zhou Shane McCarthy Christopher W. Wheat Florence Piron-Prunier Christelle Monsempes Marie-Christine François Paul Jay Camille Noûs Emma Persyn Emmanuelle Jacquin-Joly Camille Meslin Nicolas Montagné Claire Lemaitre Marianne Elias 《Molecular ecology resources》2023,23(4):872-885
The ithomiine butterflies (Nymphalidae: Danainae) represent the largest known radiation of Müllerian mimetic butterflies. They dominate by number the mimetic butterfly communities, which include species such as the iconic neotropical Heliconius genus. Recent studies on the ecology and genetics of speciation in Ithomiini have suggested that sexual pheromones, colour pattern and perhaps hostplant could drive reproductive isolation. However, no reference genome was available for Ithomiini, which has hindered further exploration on the genetic architecture of these candidate traits, and more generally on the genomic patterns of divergence. Here, we generated high-quality, chromosome-scale genome assemblies for two Melinaea species, M. marsaeus and M. menophilus, and a draft genome of the species Ithomia salapia. We obtained genomes with a size ranging from 396 to 503 Mb across the three species and scaffold N50 of 40.5 and 23.2 Mb for the two chromosome-scale assemblies. Using collinearity analyses we identified massive rearrangements between the two closely related Melinaea species. An annotation of transposable elements and gene content was performed, as well as a specialist annotation to target chemosensory genes, which is crucial for host plant detection and mate recognition in mimetic species. A comparative genomic approach revealed independent gene expansions in ithomiines and particularly in gustatory receptor genes. These first three genomes of ithomiine mimetic butterflies constitute a valuable addition and a welcome comparison to existing biological models such as Heliconius, and will enable further understanding of the mechanisms of adaptation in butterflies. 相似文献
9.
Patrick Forterre Fabrice Confalonier Franck Charbonnier Michel Duguet 《Origins of life and evolution of the biosphere》1995,25(1-3):235-249
All present-day hyperthermophiles studied so far (eitherBacteria orArchaea) contain a unique DNA topoisomerase, reverse gyrase, which probably helps to stabilize genomic DNA at high temperature. Herein the data relating this enzyme is reviewed and discussed from the perspective of the nature of the last detectable common ancestor and the origin of life. The sequence of the gene encoding reverse gyrase from an archaeon,Sulfolobus acidocaldarius, suggests that this enzyme contains both a helicase and a topoisomerase domains (Confalonieriet al.,Proc. Natl. Acad. Sci., 1993, 90, 4735). Accordingly, it has been proposed that reverse gyrase originated by the fusion of DNA helicase and DNA topoisomerase genes. If reverse gyrase is essential for life at high temperature, its composite structure suggests that DNA helicases and topoisomerases appeared independently and first evolved in a mesophilic world. Such scenario contradicts the hypothesis that a direct link connects present day hyperthermophiles to a hot origin of life. We discuss different patterns for the early cellular evolution in which reverse gyrase appeared either before the emergence of the last common ancestor ofArchaea, Bacteria andEucarya, or in a lineage common to the two procaryotic domains. The latter scenario could explain why all today hyperthermophiles are procaryotes. 相似文献
10.
Fabrice Cornille Loïc Martin Christine Lenoir Didier Cussac Bernard P. Roques Marie-Claude Fournié-Zaluski 《Letters in Peptide Science》1997,4(4-6):207-212
The light chain of tetanus neurotoxin (TeNT L chain)has been shown to be endowed with zinc endopeptidaseactivity, selectively directed towards theGln76–Phe77 bond of synaptobrevin, avesicle-associated membrane protein criticallyinvolved in neuroexocytosis. In previous reports,truncations at the NH2- and COOH-terminus ofsynaptobrevin have shown that the sequence 39–88 ofsynaptobrevin is the minimum substrate of TeNT,suggesting either the requirement of a well-definedthree-dimensional structure of synaptobrevin or a rolein the mechanism of substrate hydrolysis for residuesdistal from the cleavage site. In this study, theaddition of NH2- and COOH-terminal peptides ofsynaptobrevin, S 27–55 (S1) and S 82–93(S2), to the synaptobrevin fragment S 56–81allowed the cleavage of this latter peptide by TeNT tooccur. This appears to result from an activationprocess mediated by the simultaneous binding ofS1 and S2 with complementary sites presenton TeNT as shown by surface plasmon resonanceexperiments. All these results favor anexosite-controlled hydrolysis of synaptobrevin by TeNTprobably involving a conformational change of thetoxin. This could account for the high degree ofsubstrate specificity of TeNT and, probably, botulinumneurotoxins. 相似文献