Comptes rendus hebdomadaires des seances de l'Academie des sciences. Serie D: Sciences naturelles最新文献

The iodide-peroxidase activity of the thyroid gland remains, in hypophysectomized Rats maintained on a low iodine diet, below normal value. This result suggests that the early increase of peroxidase activity observed in control Rats maintained on a low iodine diet is TSH dependent.

Synthetic reticulated polysaccharides grafted with linear amino-acids or amines have been submitted to the test of localized hemolysis in gel (Jerne). Some of them show a statistically highly significant immuno-stimulating power in Mice.

The whole genome of the hepatitis B virus (Dane particles) was inserted in vitro in the genome of the bacteriophage lambda gtWES . LAMBDA B. The recombinant DNA molecule was cloned in E. coli. Amplification of the hybrid bacteriophage enables the preparation of large amounts of hepatitis B virus DNA. The possibilities offered by the utilization of this recombinant bacteriophage are discussed.

The presence of a protein that binds specifically and with high affinity to progesterone is found in the plasma of fetal guinea Pig. Progesterone and 5 alpha-dihydroxyprogesterone strongly compete for the 3H-progesterone-protein complex. 5 beta-dihydroxy progesterone, 20 beta-dihydroxyprogesterone, testosterone and synthetic progestagen, R-5020 (17,21-dimethyl-19-norpregna-4, 9-diene-3,20 dione), also compete but less intensely. 17-hydroxyprogesterone, aldosterone, cortisol, oestradiol and oestrone have no effect. The 3H-progesterone-protein, complex has an affinity of Kd = 8.8 +/- 3.5 x 10(-10) M and in sucrose density gradient the sedimentation coefficient is 4.6 S.

After a treatment of early embryos by AMPc, only 40% of the primordial germ cells are found in the gonads; the others are found in the dorsal mesentery and especially in the intestinal wall.

The nucleolus organizer regions can be selectively stained in metaphase chromosome preparations by the Goodpasture and Bloom's technique which was adapted to electron microscopy analysis of cells during interphase. Using this technique, a selective accumulation of silver grains was observed over nucleolus light areas. This selective accumulation allows the identification of the interphase fibrillar centers as the nucleolus organizer regions. Ultrastructural relationships between fibrillar centers and dense fibrillar component are discussed.

In the Frog, after unilateral optic nerve and tract section, contralateral visual responses were recorded in the tectum ipsilateral to the section. These responses were elicited by stimulation of a unique spatial region located near the projection of the contralateral eye optic axis and could be randomly recorded on the tectal surface. The possible pathways and the role of such retino-tectal afferences are discussed.

Male and female silver eels, in fresh water or sea water, have few gonadotrophs (GTH) poorly differentiated. An oestradiol (E2) treatment induces their development: a well developed Golgi area, abundant secretory granules (200-500 nm), dilated cisterna and large globules 1.2-2.2 micron) are observed. A positive feedback may control gonadotropin synthesis in immature eels. No macroscopic effect is discernible on the gonad.

The centriole could constitute a system of inertia in the cell, providing the system of references controlling the movement of the cell. It would ensure equally the coherence of cell metabolism and its stability. The origin and functioning of the centriole would be linked to a singel physical phenomenon.

Endopolygalacturonase has been purified by binding on Sepharose 6 B gel; studies on interactions between agarose and the enzymes have shown that endopolygalacturonase chromatography on Sepharose 6 B was on ion-exchange chromatography and did not involve biospecific interactions.