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

Fluid obtained from Rat uteri during the uterine state of non-receptivity refractory for nidation, contains a substance of about 700 dalton (blastocidin) which exerts a lethal effect on Rat blastocysts in vitro.

We present a model for the secondary structure of 16S ribosomal RNA from E. coli. This model has been deduced by restricting the total number of theoretical base pairings using the following criteria: (1) susceptibility of residues towards enzymatic probes that are specific for either paired or single stranded regions; (2) reactivity of certain residues to chemical modification; (3) evidence for medium and long range interactions; (4) comparative analysis of ribosomal RNA sequences from other organisms.

The inhibiting effect of Cytembena on HeLa cell kinetics has been demonstrated and analyzed. The percentage of cycling cells decreases, according to the concentration, between 7.5 and 2.5 x 10(-5) M. Estimation of DNA by cell flow cytophotometry shows an important shift in the distribution of cycling cells with a relative decrease of G1 cells and a very important accumulation of G2 cells. According to our experimental conditions, the blocking up in G2 is irreversible only at 7.5 x 10(-5) M.

OEnanthotoxin applied locally onto the Cat cortex produced a long-lasting epileptic focus. The basic cortical level of extracellular calcium concentration ([Ca2+]e) was decreased before the actual onset of paroxysmal discharges. In the active focus the [Ca2+]e decrease induced by a cortical or a thalamic stimulation was larger than in normal cortex. Maximal decreases were found at a depth of 300 micrometer below cortical surface. It is suggested that at this cortical level calcium conductances are increased by oenanthotoxin. This increase may be one of the mechanisms of onset of epileptic seizures.

Local hyperthermia--insufflation in the upper respiratory paths of humidified air at 43 degrees C, three 30 min sessions at 2-3 hrs. interval--cures a high percentage of infective Coryza and exerts a prolonged beneficial effect on an important fraction of persistent allergic rhinitis.

A frozen strain of Plasmodium yoelii nigeriensis is inoculated at 4 pm, midnight and 9 am onto inbred Mice. In all instances young gametocytes (type 0) appear in the blood only between 10 am and 6 pm. Although the erythrocytic schizogony occurs regularly during the whole circadian period, the latency increases progressively when the infective subinoculations are made at midnight, 4 pm and 9 am. Possibly, the infective merozoite can only enter the red blood cell around midnight.

In the Baboon, two regions could be distinguished within the dentate nucleus according to the complexity of motor effects induced through localised electrical stimulation. (a) A rostromedial region, from which synergistic effects were elicited. This part mainly controls proximal muscles. (b) A caudolateral region from which simple movements were induced. A separate area for hand control could be identified within this part of the nucleus.

Casein is submitted to a severe alkaline treatment (NaOH 0,2 or 0,5 N, 1 hr., 80 degrees C). The hydrolysis by pancreatic enzymes (trypsin or chymotrypsin) is reduced in vitro and, in the case of the more severe treatment, stopped. After an extended (24 hrs.) trypsin and pronase hydrolysis, it is shown, by affinity chromatography, that peptides, which are not hydrolysable, can bind to trypsin and inactivate this enzyme in vitro.

H-flavocytochrome b2, a tetramer enzyme, is inactivated, at low ionic strength and can be reactivated, increasing the ionic strength of the medium. The inactivation-reactivation process was structurally manifested by a dissociation-association phenomenon between subunits. It was clearly shown that the inactivation-dissociation process appeared independent of enzyme concentration whereas the reactivation-association phenomenon was enzyme concentration dependent. However, proteins protect H-flavocytochrome b2 from inactivation-dissociation, only when electrostatic interactions are possible between the two proteins: Horse heart cytochrome c was a good protector whereas serum albumin had no protector effect.

A "fraction P" analogue possessing immunosuppressive properties during pregnancy in the Salamandra, can be induced by treating males and females with oestradiol. Both fractions possess the same physiochemical characteristics, and equally react against a Rabbit immune serum anti "fraction P" of pregnant Salamandra. But the proteic fraction induced by hormonal treatment does immunosuppressive properties.