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51.
52.
53.
Short- and Long-Term Alterations of Gene Expression in Limbic Structures by Repeated Electroconvulsive-Induced Seizures 总被引:4,自引:2,他引:2
Vincent Leviel Catherine Fayada Bernard Guibert Michel Chaminade Georges Machek Jacques Mallet Nicole Faucon Biguet† 《Journal of neurochemistry》1990,54(3):899-904
Rats were submitted to a series of 10 daily electroconvulsive shocks (ECS). A first group of animals was killed 1 day after the last seizure and a second group 30 days later. Tyrosine hydroxylase (TH) activity was measured using an in vitro assay in the nucleus caudatus, anterior cortex, amygdala, substantia nigra, ventral tegmental area, and locus ceruleus. The mRNA corresponding to this enzyme (TH-mRNA) was evaluated using a cDNA probe at the cellular level in the ventral tegmental area, substantia nigra, and locus ceruleus. Met-enkephalin (MET)-immunoreactivity and the mRNA coding for the preproenkephalin (PPE-mRNA) were assayed in striatum and the central nucleus of the amygdala. The day after the last ECS an increase of TH activity was observed in the ventral tegmental area, locus ceruleus, and substantia nigra in parallel with a similar increase in the amygdala and striatum; in the anterior cortex TH activity remained unchanged. TH-mRNA was increased in the locus ceruleus, evidencing the presence in this structure of a genomic activation. The amounts of MET and PPE-mRNA were unaffected in the striatum but increased in the amygdala. Thirty days after the last ECS we observed a decrease of TH activity in the amygdala and of TH-mRNA amount in the ventral tegmental area. In the locus ceruleus TH-mRNA remained higher in treated animals than in controls whereas TH activity returned to control levels. These results demonstrate that a series of ECS induces an initial increase of the activity of mesoamygdaloid catecholaminergic neurons followed by a sustained decrease through alterations of TH gene expression which could mediate the clinical effect of the treatment. 相似文献
54.
Freeze fracturing of Myxosporidian spores reveals the occurrence of a continuous layer of transmembrane particles all over the surface area of the valve cells which form the spore envelope. These particles are densely packed all over the P face membrane. Due to their polygonal outline, their diameter (6-7 nm) and their central core, they resemble the particles forming the connections of gap junctions which metabolically couple the neighboring cells in animal tissues. In the present report, the role of the transmembrane particles is still hypothetical. However, they might represent a membrane structural specialization of the spores which are submitted to osmotic variations of the fluid external medium. Furthermore similar transmembrane particles are observed at the level of the septate junction which seals the valve cells. In this occurrence, they are arranged in a series of 40 double rows parallel to the suture of the spore envelope. These findings support the view that Myxosporidia are Metazoa and raise the problem of their origin. 相似文献
55.
We have isolated from the ovine rumen eight bacterial strains belonging to the speciesButyrivibrio fibrisolvens. DNA hybridization studies showed that the eight strains could be divided into four homology groups, of which none was closely related to the type strain ATCC 19171. Measurement of cross-hybridization between selected pairs of bacterial strains showed that DNA types which produced low, but significant, cross-hybridization on dot-blots were able to form heteroduplexes with between 8.4% and 32.9% of the efficiency of homoduplex formation. Thermal denaturation of the same heteroduplexes resulted in Tm values 6.4–7.5°C lower than those of the homologous duplexes formed under the same conditions. In some cases, hybridization between strains was below the level of reliable measurement. Similar experiments with ten recently isolated strains ofBacteroides ruminicola sub-sp.brevis revealed a similar degree of genetic divergence between isolates. 相似文献
56.
E Boukhzer A Ennya F Felden A Gérard E Nexo J P Nicolas H Gérard J L Guéant 《Biochimica et biophysica acta》1992,1175(1):128-131
Specific binding sites for rabbit transcobalamin II have been found on isolated adult rabbit germ cells. Scatchard analysis revealed a single class of binding sites for [57Co]cyanocobalamin-transcobalamin II with an association constant (Ka) of 1.3 x 10(10) M-1 and 700 sites per cell. Binding was reversible, saturable and calcium dependent. Electron microscope radioautography following incubation with iodinated transcobalamin II at 4 degrees C led to a detectable labeling mainly restricted to the plasma membrane. 相似文献
57.
Véronique Guellec Chantal David Michel Branchard Jacques Tempé 《Plant Cell, Tissue and Organ Culture》1990,20(3):211-215
Genetically transformed grapevine (Vitis vinifera L.) roots were obtained after inocultation of in vitro grown whole plants (cv. Grenache) with Agrobacterium rhizogenes. The strain used contains two plasmids: the wild-type Ri plasmid pRi 15834 and a Ti-derived plasmid which carries a chimaeric neomycin phosphotrans-ferase gene (NPT II) and the nopaline synthase gene. Expression of the NPT II gene can confer kanamycin resistance to transformed plant cells. Slowly growing axenic root cultures derived from single root tips were obtained. Opine analysis indicated the presence of agropine and/or nopaline in established root cultures. For one culture, the presence of T-DNA was confirmed by dot-blot hybridization with pRi 15834 TL-DNA. Callogenesis was induced by subculturing root fragments on medium supplemented with benzylaminopurine and indoleacetic acid.Transformation of in vitro cultured grapevine cells has recently been reported (baribault T.J. et al., Plant Cell Rep (1989) 8: 137–140). In contrast with the results presented here, expession of the NPT II gene Conferred kanamycin resistance to Vitis vinifera calli that was sufficient for selection of trasformed cells.Abbreviations BAP
benzylaminopurine
- IAA
indoleacetic acid
- NAA
naphtaleneacetic acid
- NPT II
neomycin phosphostransferase II
- EDTA
ethylenediaminetetraacetic acid 相似文献
58.
Cor Glas Jolanda C. Kamp Coby Jongsma H. John J. Nijkamp Jacques Hille 《Plant science》1990,70(2):231-241
Lincomycin-resistant calli were induced from both Lycopersicon esculentum and Lycopersicon peruvianum using N-mitroso-N-methylurea (NMU) mutagenesis. From these calli lincomycin-resistant plants were regenerated. For L. peruvianum it was shown that the resistant plants could be divided in two classes with respect to their resistance to lincomycin and its derivative clindamycin. The first class comprised plants which were resistant to 500 mg/l lincomycin and showed no shoot or root formation in the presence of clindamycin; the second class consisted of plants resistant to 2000 mg/l lincomycin and these plants were able to form shoots and roots on clindamycin containing media. Lincomycin is an inhibitor of peptidyltransferase; chloroplast encoded parts of this enzymatic function are sensitive for this antibiotic. Reciprocal crosses between our lincomycin resistant and wild type L. peruvianum plants indicated a maternal inheritance of the mutation. 相似文献
59.
Jacques Ricard Jacques Vergne Jean-Luc Decout Marie-Christine Maurell 《Journal of molecular evolution》1996,43(4):315-325
A polyallylamine carrying long hydrophobic dodecyl groups and adenine residues as side chains (PALAD C12) may be able to catalyze the hydrolysis ofN-carbobenzoxy-l-alaninep-nitrophenyl ester (N-Cbz-Ala) as well asp-nitrophenyl acetate (pNPA). The progress curve of hydrolysis of the former displays a long lag and apparently no steady state.
After this transient the rate falls off due to the accumulation of the products. Conversely, the hydrolysis ofp-nitrophenyl acetate displays classical burst kinetics followed by a slow decline of the reaction rate.
Theoretical considerations show that a steady state may be expected to occur only if the concentration of the free catalyst
is very small during the reaction. This condition is sufficient to allow the rate of disappearance of the substrate to be
equal to the rate of appearance of the products, which is precisely a condition for the existence of a steady state. If the
catalyst is poorly active and has a loose affinity for its substrate and product, the measurement of a significant reaction
rate will require a much larger concentration of the catalyst. Therefore, under these conditions, one cannot expect a steady
state to occur. The mathematical expression of the error made in the steady-state assumption has been derived. This error
increases with the catalyst concentration and decreases if the affinity of the substrate for the catalyst is high. Therefore
the lack of steady state is associated with the affinity (or the dissociation) of the substrate and the product for the catalyst.
When this affinity is low, the free concentration of the catalyst during the reaction is high and one cannot expect a steady
state to occur. This is precisely what takes place with N-Cbz-Ala.
A mathematical expression of the rate of hydrolysis of N-Cbz-Ala and of any reactant that displays this type of kinetics may
be derived at the end of the transient when the rate is close to its maximum value. Under these conditions the rate cannot
follow classical Michaelis-Menten kinetics and displays positive cooperativity.
It may therefore be speculated that primordial template-like catalysts that were displaying a poor affinity for their substrates
and products were already exhibiting apparent positive cooperativity in the kinetic reactions they were able to catalyze.
Correspondence to: J. Ricard 相似文献
60.
Cyclothiazide Unmasks an AMPA-Evoked Release of Arachidonic Acid from Cultured Striatal Neurones 总被引:2,自引:2,他引:0
Abstract: The joint, but not independent, activation of α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) and metabotropic glutamate receptors induces liberation of arachidonic acid from cultured mouse striatal neurones. We examined whether blocking AMPA receptor desensitisation with cyclothiazide would modify this response. Cyclothiazide strongly potentiated the combined AMPA/(1 S ,3 R )-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD)-evoked release of arachidonic acid (EC50 of ∼7 µ M ) but did not modulate the basal, ACPD, or NMDA response. The enhanced liberation of arachidonic acid, observed in the presence of cyclothiazide, was due to the appearance of a genuine AMPA response that was independent of an associative activation of metabotropic receptors. The potentiated and nonpotentiated AMPA responses were inhibited by both competitive [2,3-dihydroxy-6-nitro-7-sulphamoylbenzo( f )quinoxaline] and 2,3-benzodiazepine noncompetitive (GYKI 53655 and GYKI 52466) receptor antagonists. Cyclothiazide was equally effective at potentiating the AMPA response in either the presence or absence of glucose, suggesting that the increased glutamate-evoked arachidonic acid release observed in these cells under conditions of glucose deprivation is not due to reduced AMPA receptor desensitisation. The enhanced liberation of arachidonic acid measured in the presence of cyclothiazide appeared to result from a large (fourfold) elevation of the AMPA-induced increase in intracellular calcium level. Therefore, an AMPA-evoked mobilisation of arachidonic acid could potentially contribute to non-NMDA receptor-mediated neurotoxicity, which has been observed in neuronal cells in the presence of cyclothiazide. 相似文献