MK-801 Prevents 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Induced Parkinsonism in Primates

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.     

The R1 gene conferring race-specific resistance to Phytophthora infestans in potato is located on potato chromosome V.

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.     

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

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.     

The autonomic innervation of rat jugular vein

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.     

The effect of aphidicolin on the rate of DNA replication and unscheduled DNA synthesis of Bloom syndrome and normal fibroblasts

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.     

Etude de la dynamique des populations de cilies d'un torrent experimental pendant deux annees

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

     

Photosensory transduction in Euglena gracilis: Effect of some metabolic drugs on the photophobic response

We have investigated the effect of some metabolic drugs, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 2,4-dinitrophenol (DNP), sodium azide (NaN₃), on the photobehavior of single cells of Euglena gracilis, in order to clarify the relevance of different metabolic pathways in the process of photoperception and sensory transduction in this alga. The results obtained show that the photophobic response of Euglena is not affected by the action of these drugs. This suggests that neither the photosynthetic process nor oxidative phosphorylation play a significant role in the phenomenon of photosensory transduction in Euglena.List of Abbreviations DNP 2,4-dinitrophenol - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - PSI Photosystem I - PSII Photosystem II     

Nuclear protein synthesis in regenerating rat liver : Selective histone inhibition by α-amanitin

Nuclear protein synthesis has been studied in regenerating rat hepatocytes after partial hepatectomy and α-amanitin treatment. The toxin induced a marked and precocious inhibition of histone synthesis without affecting the acidic nuclear proteins. This inhibition preceded the inhibition of DNA synthesis. The modification of polyribosome profile and of [¹⁴C]lysine incorporation on synthesized polypeptides were consistent with a reduction of specific mRNAs.