Comptes rendus des seances de l'Academie des sciences. Serie III, Sciences de la vie最新文献

Xanthine oxidase activity: NAD+-dependent form (D) and O2-dependent form (O) were carried out in cytosol supernatants of connective tissue growth (T.C.N.F.), skin tail, liver and plasma of carrageenan induced granuloma in the Rat. The specific activities of skin, liver and plasma were normal in animals with a granuloma. The total specific activity (D + O): 7.53 +/- 0.98 mU/mg protein, and the percentage of form O: 51.6 +/- 5.1 of the granulomatous tissue as compared to the tail are significantly increased. These results suggest the likely function of xanthine oxidase during the inflammatory response.

Streptococcus pneumoniae can be transformed by DNA. Transformation occurs in a transitory physiological state called competence. We observed a modulation of the Vi of aminoacid uptakes which seems selectively related to the energy coupling of the corresponding transports.

The treatment of human polymorphonuclear cells by neuraminidase "type-X" removes about 15% of cell sialic acid without modifications of NADPH oxidase activity of granulocytes before and after stimulation by opsonized zymosan. A mild periodate treatment oxidizes only the poly-hydroxilic chain of sialic acid with formation of aldehyde groups. This treatment increases cellular NADPH oxidase activity and also largely prevents the stimulation of polymorphonuclear cells by opsonized zymosan.

Ultrastructural immunocytochemistry with anti-insulin antiserum allowed the detection of insulin antigenic sites localized at the inner aspect of the cisternae of the Golgi apparatus in pancreatic B-cells. By contrast, in secretory granules released from the Golgi apparatus, insulin antigenic sites were localized over the granule content but not on the membrane. The demonstration of insulin antigenic sites at the level of the Golgi membranes is compatible with the presence of specific insulin receptors and/or charge interactions between the insulin and the membrane. Binding at this level could in turn be involved in the sorting out of insulin polypeptides destined to be concentrated in secretory granules.

The adenylate cyclase activity of Rat brain synaptosomal membranes is strongly activated by forskolin. This study demonstrates: 1. That GTP or its analogs, when added to forskolin, decrease the enzyme stimulation by a factor of 40 to 60%; 2. That Pertussis toxin (TP), in the presence of NAD, ADP-ribosylates a single membrane protein of 40,000 dalton apparent molecular weight in a strictly concomitant manner. This Lubrol-soluble protein has a sedimentation coefficient of 3.6 and a Stokes radius of 6 nm. An immune serum against TP blocks the NAD-glycohydrolase activity of the toxin.

We have studied the in vitro malignant progression of human lymphoid cells by the combined effect of genetic, viral and mutagenic factors. A lymphoblastoid cell line immortalized by Epstein-Barr virus was used; it was derived from a patient suffering from ataxia-telangiectasia, a genetic disease linked to a deficiency in DNA repair. Cells were treated by sub-toxic doses of two potent mutagens (carcinogens), NQO (4-nitroquinolein-oxid) and R 7 000 (2-nitro-7-methoxy-naphto-furan). The treated cells showed an increased ability to form colonies in soft agarose, among which some compact colonies appeared, different from the diffuse colonies formed by untreated control cells. Sub-clones derived from these compact colonies differ also from the original cells by their behavior in liquid culture medium, by their increased tumorigenicity in Nude Mice and by their capacity to form nodules on Chicken chorioallantoic membrane. Some of the sub-clones produce non-regressing large tumors in Nude Mice with a cell inoculum lower than that required for Burkitt lymphoma cells while being less invasive than the latter. However, by their morphology, the malignant cells of the sub-clones remain similar to the original lymphoblastoid cells. Thus, such a malignant progression obtained in vitro cannot be considered as identical to that which leads to Burkitt lymphoma in African children.

A 431 nucleotide sequence from the central break region of Drosophila 26S rRNA precursor has been established by sequencing the corresponding region of the 26S gene. The analysis of rDNA-mature 26S rRNA hybrids submitted to S1 nuclease digestion has allowed us to show that a 75 +/- 3 nucleotide A-U rich RNA fragment is excised during the processing of the precursor.

A molecular model is proposed for Angiotensin II which could be close to an active form. This model corresponds to a complexed conformation and agrees with many experimental results. Its conformational energy ranges around the conformations already proposed, so that complexation must highly favour it.

Effect of injection of Arachis hypogea (PNA) and Soybean (SBA) lectins on the migration of Xenopus primordial germ cells (PGCs) were investigated. PNA inhibited almost entirely the PGCs migration, more than SBA. Our results indicated that the inhibition of the migration could be a consequence of the lectin-induced alterations of cell surface properties.

19 antibodies specific for 11 different drugs were extensively tested in the presence of the drug against a panel of red cells including common and public minus phenotypes. High incidence blood group antigens were shown to be specific receptors for several drug-antibody complexes proving thereby that red blood cells play more than an "innocent bystander" role in drug induced immune hemolytic anemias.