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81.
Alessandro Zuddas Germano Oberto Francesca Vaglini Flavia Fascetti Francesco Fornai Giovanni U. Corsini 《Journal of neurochemistry》1992,59(2):733-739
In cynomologus monkeys, systemic administration of MK-801, a noncompetitive antagonist for the N-methyl-D-aspartate receptor, prevented the development of the parkinsonian syndrome induced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). MK-801 also attenuated dopamine depletion in the caudate and putamen and protected dopaminergic neurons in the substantia nigra from the degeneration induced by the neurotoxin. Nevertheless, 7 days after MPTP administration in the caudate and putamen of monkeys also receiving MK-801, the levels of toxic 1-methyl-4-phenylpyridinium were even higher than those measured in monkeys receiving MPTP alone. This indicates that the protective action of MK-801 is not related to MPTP metabolism and strongly suggests that, in primates, the excitatory amino acids could play a crucial role in the mechanism of the selective neuronal death induced by MPTP. 相似文献
82.
The R1 gene conferring race-specific resistance to Phytophthora infestans in potato is located on potato chromosome V. 总被引:5,自引:0,他引:5
Christiane Leonards-Schippers Werner Gieffers Francesco Salamini Christiane Gebhardt 《Molecular & general genetics : MGG》1992,233(1-2):278-283
Summary Late blight in potato is caused by the fungusPhytophthora infestans and can inflict severe damage on the potato crop. Resistance toP. infestans is either based on major dominantR genes conferring vertical, race-specific resistance or on minor genes inducing horizontal, unspecific resistance. A dihaploid potato line was identified which carried theR1 gene, conferring vertical resistance to allP. infestans races, with the exception of those homozygous for the recessive virulence allele of the locusV1. The F1 progeny of a cross between this resistant parent P(R1) and P(r), a line susceptible to all races, was analysed for segregation ofR1 and of restriction fragment length polymorphism (RFLP) markers distributed on the potato RFLP map comprising more than 300 loci. TheR1 locus was mapped to chromosome V in the interval between RFLP markers GP21 and GP179. The map position ofR1 was found to be very similar to the one ofRx2, a dominant locus inducing extreme resistance to potato virus X. 相似文献
83.
Purification and further characterization of the second nitrate reductase of Escherichia coli K12 总被引:6,自引:0,他引:6
Two nitrate reductases, nitrate reductase A and nitrate reductase Z, exist in Escherichia coli. The nitrate reductase Z enzyme has been purified from the membrane fraction of a strain which is deleted for the operon encoding the nitrate reductase A enzyme and which harbours a multicopy plasmid carrying the nitrate reductase Z structural genes; it was purified 219 times with a yield of about 11%. It is an Mr-230,000 complex containing 13 atoms iron and 12 atoms labile sulfur/molecule. The presence of a molybdopterin cofactor in the nitrate reductase Z complex was demonstrated by reconstitution experiments of the molybdenum-cofactor-deficient NADPH-dependent nitrate reductase activity from a Neurospora crassa nit-1 mutant and by fluorescence emission and excitation spectra of stable derivatives of molybdoterin extracted from the purified enzyme. Both nitrate reductases share common properties such as relative molecular mass, subunit composition and electron donors and acceptors. Nevertheless, they diverge by two properties: their electrophoretic migrations are very different (RF of 0.38 for nitrate reductase Z versus 0.23 for nitrate reductase A), as are their susceptibilities to trypsin. An immunological study performed with a serum raised against nitrate reductase Z confirmed the existence of common epitopes in both complexes but unambiguously demonstrated the presence of specific determinants in nitrate reductase Z. Furthermore, it revealed a peculiar aspect of the regulation of both nitrate reductases: the nitrate reductase A enzyme is repressed by oxygen, strongly inducible by nitrate and positively controlled by the fnr gene product; on the contrary, the nitrate reductase Z enzyme is produced aerobically, barely induced by nitrate and repressed by the fnr gene product in anaerobiosis. 相似文献
84.
85.
The human ryanodine receptor gene: Its mapping to 19q13.1, placement in a chromosome 19 linkage group, and exclusion as the gene causing myotonic dystrophy 总被引:10,自引:1,他引:9 下载免费PDF全文
Alex E. MacKenzie Robert G. Korneluk Francesco Zorzato Junichi Fujii Michael Phillips David Iles B Wieringa Suzanne Leblond Jane Bailly Huntington F. Willard Catherine Duff Ronald G. Worton David H. MacLennan 《American journal of human genetics》1990,46(6):1082-1089
The recent cloning of cDNA encoding the Ca++ release channel (ryanodine receptor) of human sarcoplasmic reticulum has enabled us to use somatic cell hybrids to localize the ryanodine receptor gene (RYR) to the proximal long arm of human chromosome 19. Studies with additional hybrids containing deletions or translocations in chromosome 19 enabled us to localize RYR to 19q13.1 in a region distal to GPI/MAG and proximal to D19S18/DNF11. On the basis that the myotonic dystrophy (DM) locus maps near this region and that myotonia could result from a defect in the ryanodine receptor, we examined the linkage between the DM locus and RYR. Our results, showing several DM-RYR recombinants, rule out an RYR defect as the cause of DM. However, localization of RYR to a region of human chromosome 19 which is syntenic to an area of pig chromosome 6 containing the HAL gene responsible for porcine malignant hyperthermia supports the candidacy of RYR for this disorder. 相似文献
86.
Giuseppe Sancesario Carlo Cavallotti Dr. Francesco Amenta 《Cell and tissue research》1982,227(3):691-693
Summary The autonomic innervation of rat jugular vein was studied using glyoxylic acid fluorescence and acetylcholinesterase histochemical methods. The rat jugular vein is provided with both adrenergic and cholinergic nerve fibers organized in plexuses located at the adventitial-medial border. The existence of these nerve plexuses does not seem to support biochemical findings that suggest a lack of innervation in the rat jugular vein and which propose this blood vessel as a model for the analysis of drug-smooth muscle cell interaction without the interference of neuronal uptake mechanisms. 相似文献
87.
Summary Ultraviolet radiation induced more unscheduled DNA synthesis (UDS) in ten Bloom syndrome (BS) fibroblast strains than in control cells, but this difference could be suppressed by aphidicolin treatment in at least nine BS strains. Aphidicolin, 1 and 5 g/ml, were required to inhibit by 30% the UDS of BS and control cells respectively, but the DNA replication of BS cells did not prove abnormally sensitive to such an inhibitor. These findings are discussed in relation to current knowledge of the action of aphidicolin and hypotheses of the metabolic defect in BS. 相似文献
88.
The sampling of Ciliates performed in a little experimental torrent through two years, showed a great similarity of the two annual cycles. This similarity concerns both the species composition as well as the dynamics of the Ciliates populations. The basic species which affect the community structure are as follows: Ctedoctema acanthocrypta, Mesodinium acarus, Cyclidium glaucoma, Cinetochilum margaritaceum, Pleuronema coronatum, Lacrymaria pupula, Aspidisca costata and Holosticha vernalis. The dynamics of the ciliated Protozoa living in this environment seem to be influenced by the speed of the current, the temperature and the amount of dissolved organic matter in the water.
Etude de la dynamique des populations de cilies d'un torrent experimental pendant deux annees相似文献
89.
90.
Lack of Spontaneous Sister Chromatid Exchanges in Somatic Cells of DROSOPHILA MELANOGASTER 下载免费PDF全文
Neural ganglia of wild type third-instar larvae of Drosophila melanogaster were incubated for 13 hours at various concentrations of BUdR (1, 3, 9, 27 micrograms/ml). Metaphases were collected with colchicine, stained with Hoechst 33258, and scored under a fluorescence microscope. Metaphases in which the sister chromatids were clearly differentiated were scored for the presence of sister-chromatid exchanges (SCEs). At the lowest concentration of BUdR (1 microgram/ml), no SCEs were observed in either male or female neuroblasts. The SCEs were found at the higher concentrations of BUdR (3, 9, And 27 micrograms/ml) and with a greater frequency in females than in males. Therefore SCEs are not a spontaneous phenomenon in D. melanogaster, but are induced by BUdR incorporated in the DNA. A striking nonrandomness was found in the distribution of SCEs along the chromosomes. More than a third of the SCEs were clustered in the junctions between euchromatin and heterochromatin. The remaining SCEs were preferentially localized within the heterochromatic regions of the X chromosome and the autosomes and primarily on the entirely heterochromatic Y chromosome.--In order to find an alternative way of measuring the frequency of SCEs in the Drosophila neuroblasts, the occurrence of double dicentric rings was studied in two stocks carrying monocentric ring-X chromosomes. One ring chromosome, C(1)TR94--2, shows a rate of dicentric ring formation corresponding to the frequency of SCEs observed in the BUdR-labelled rod chromosomes. The other ring studied, R(1)2, exhibits a frequency of SCEs higher than that observed with both C(1) TR94--2 and rod chromosomes. 相似文献