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In red blood cells, a modulation of the level of the allosteric effector of hemoglobin, 2,3-diphosphoglycerate (2,3-DPG) would have implications in the treatment of ischemia and sickle cell anemia. Its concentration is determined by the relative activities of the synthase and phosphatase reactions of the multifunctional bisphosphoglycerate mutase (BPGM). In this report we develop first a more direct...
The phylogenetic position of the platyhelminths within the metazoan tree is examined using two independent sets of molecular characters, the evolution of 18S ribosomal RNA sequences and the diversity of the genes belonging to the HOX cluster. Among the various hypotheses that have been considered by zoologists, a position of the platyhelminths within the protostomes, related to the phyla with typical...
A model coupling a 2D transport equation and a simple model of the nitrogen cycling was developed for the Thau lagoon (France). The model took into account the wind forcing on the hydrodynamism, the effect of the temperature on the biological processes, the input of the watershed area, the light dependence of the pelagic primary production and the predation of the phytoplankton by the cultivated...
Calcification of non-osseous tissues such as heart valves or vessels is a major concern in clinical practice. The exact mechanism is still unknown. Numerous studies have shown that mineral deposits of crystalline hydroxyapatite within these tissues were associated with increased non-collagenous protein content. More recently osteopontin was found to be associated with calcification in living tissues...
Seed-eating in the African colobines varies according to species and site. Because seeds are more palatable than leaves, seed-eating is considered to result from a positive choice by colobines. A year-long study of the diet ofColobus satanas in Central Gabon confirmed that this species eats a significant amount of seeds. Furthermore, despite large variations in fruit availability, this amount consistently...
The polar coumpound hexamethylenebisacetamide (HMBA) is a differentiating agent in the murine erythroleukemia cell system (MELC). It induces, like dimethylsulfoxide, the commitment to terminal differentiation leading to a recovery in the expression of several genes like the globin gene. This molecule which also induces differentiation in other cellular types is a growth agent for human, ovine and...
In order to study the role of Fos on the regulation of proliferation in the monocyte-macrophage lineage we realized a stable transfection of the murine P388D1 cell line by the murine c-fos gene under the control of the human metallothionein IIA promoter. Several clones have been selected by geneticin: they show a variable number of integrated transgene (two to ten copies). Their expression has been...
Heptanol-sensitive gap junction communication was characterized by the gap-FRAP method (fluorescence recovery after photobleaching) in confluent rat myoblasts developing in primary culture. Cell to cell dye diffusion was mainly restricted to a short period of the prefusion lag period and disappeared during fusion promotion except between some myoblasts and myotubes. This short period of occurrence...
The cytoplasm of cultured human lymphoblasts has a particular organization. A ring formed by actin and myosin delimits a region of the cell where an active membrane veil forms. Depolymerization of the microtubular cytoskeleton releases this ring, which then oscillates between the two poles of the cell. This periodic movement has been studied and described with great precision. We have used these...
The objective of this investigation was to examine the effects of 4-hydroxytamoxifen on the uterine activity. For this, we evaluated the electrical activity of the myometrium, chronically, in conscious unrestrained rats at mid-pregnancy. We also examined the tissular progesterone and 17β-estradiol concentrations in the myometrium and uterus 6 hours after administration of 4-hydroxytamoxifen. Comparison...
Phylogenetic relationships among pitvipers are inferred from a parsimony analysis using cytochrome b DNA sequences: 396 bp in the 5' end of the gene were sequenced in eight species of pitvipers (Agkistrodon blomhoffi, Agkistrodon contortrix, Bothriechis schlegelii, Bothriopsis bilineata, Bothrops atrox, Crotalus atrox, Lachesis muta and Trimeresurus stejnegeri) and in four taxa used as outgroups (Atractaspis...
Using intraradical forms of vesicular-arbuscular mycorrhizas as starting material this paper describes a reproducible in vitro method of mycelium and spore production of Glomus intraradices and Glomus versiforme. The culture and subculture of vesicular-arbuscular mycorrhizal fungi with transformed root are suitable for an in vitro collection of fungal isolates and for increasing the fungal biomass...
Adenoviruses are very attractive vectors for gene transfer into the cardiac muscle; however, their promiscuous tissue tropism, leading to an ectopic expression of the transgene, is a considerable practical limitation. To restrict expression of a reporter gene in cultured cardiomyocytes and in the heart of the rat, we have constructed a recombinant adenovirus (Ad-MLC2βgal) containing the β-galactosidase...
Cystic fibrosis is a human monogenic genetic disease caused by mutations in the cystic fibrosis (CF) gene, which encodes a membrane protein which functions as a channel: the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The most frequent mutation, a deletion of phenylalanine F508 (ΔF508), is located in the first nucleotide binding domain of CFTR: NBF1. This mutation leads to...
On sait que le complexe Gp120-Gp41 change de conformation lorsqu'il se fixe sur le CD4. On a de bonnes raisons de penser que le CD4 change alors lui aussi de conformation. Un calcul des modes normaux de vibration des deux domaines N-terminaux du CD4 a recemment montre qu'il devrait s'agir, pour cette partie du CD4, d'un mouvement dit de charniere a. On verifie ici qu'on obtient un resultat similaire...
The locomotory and ventilatory activities and the intermediary and energy metabolism modifications of the hypogean aquatic isopod crustacean Stenasellus virei were investigated in severe hypoxia (Po 2 < 0.03 kPa) and subsequent recovery. The aims of this study were i) to determine why the subterranean species displayed a greater tolerance of hypoxia than numerous other epigean crustaceans,...
Le cytochrome P450 aromatase, produit du gene CYP19, est responsable de la transformation des androgenes en oestrogenes ; sa presence au niveau testiculaire est maintenant bien etablie. L'utilisation d'une technique de RT-PCR quantitative nous a permis d'etudier le taux de transcription du cytochrome P450arom dans les cellules somatiques purifiees de rat age de 20, 40 et 70-80 jours. L'expression...
L'eutypiose est une maladie de deperissement de la vigne due a un champignon parasite, Eutypa lata. C'est actuellement la plus grave des maladies de la vigne : elle est presente dans de nombreux vignobles a travers le monde, elle a un impact economique important et il n'existe pas de moyens de lutte curatifs. Dans cette mise au point, nous decrivons les symptomes et l'epidemiologie de la maladie,...
Surveiller l'evolution de la surface terrestre est l'une des applications majeures de la teledetection. C'est aussi l'une des preoccupations essentielles de nombreuses communautes tant scientifiques qu'economiques et politiques. La synthese qui est presentee ici concerne l'ensemble du continent africain. Elle a ete realisee sur la base d'un important volume de donnees de syntheses temporelles des...
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