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

During pseudopregnancy in the Rabbit the DNA synthesis in the uterine epithelium is very reduced. These results conjoined with the decrease of the mitotic index and previous ultrastructural observations allow to think that multinucleated cells proceed mainly by cell fusion.

Induction of synthesis of the viral antigens T and V during polyoma virus infection was studied in primary Mouse and Hamster kidney and brain cultures, as well as in various types of human cells. The results show that: (1) Despite a very low percentage of positive cells by immunofluorescence, Hamster brain cells produced more viral antigen than kidney cells, as opposed to what was found in Mouse brain cells. (2) Most human cells produced neither T nor V antigens. Conversely, a large number of brain cells synthesized the T antigen very early after infection.

In cadmium exposed Rats correlation analysis of calcium deep bone assessed by compartimental analysis and results of bone calcium determination by neutron activation shows a significative relationship between both values.

alpha MSH from the neuro-intermediate lobe of the pituitary gland of the goldfish displays a competitive behaviour in an RIA for synthetic alpha MSH. The inhibition curves from neuro-intermediate homogenates parallel the standard curve (P < 0,01) but two major pools of immunoreactive peptides have been separated by Sephadex gel chromatography. The neuro-intermediate lobe contains 480 +/- 56 ng (S.E.M.) of immunoreactive alpha MSH.

Mallory bodies (MB) are characteristic features of human and experimental hepatitis they exhibit, by electron microscope, an heterogeneous structure. We propose a mode of formation of such MB, which would take place un a progressive way from simple form (bundles of microfilaments) to complex form (typical MB).

The time course of the responses of primary endings to periodic small changes of length (de-efferented spindles of Cat soleus muscles) is progressively modified during slow muscle stretch. Alterations observed at the end of stretch suggest that they are due to the same mechanism which is responsible for the "initial burst".

Appearance of "suppressor cells" is induced by in vitro hyperimmunization of lymphocytes against allogeneic cells, incompatible for one HLA-DR antigen. These "suppressor cells under certain conditions, release in the culture medium, "suppressor factors" of the in vitro allogeneic proliferative response in Man. They are not immunoglobulins and act in a non specific way towards the stimulators. Only one of them is restricted to some individuals. This is shown when either responders or stimulators are incubated for different periods, with the "suppressor factors" prior to the primary mixed lymphocyte reaction (MLRI). The beneficial effect of transfusions on kidney graft survival, could be, in part, explained by a suppressor mechanism, analogous to the one described in vitro.

The 3' à 5' exonuclease activity of E. coli DNA-polymerase I is inhibited by nucleotides and deoxynucleotides at concentrations (< 1 mM) where polymerase activity is not affected. This inhibitory effect depends on the nature of the excised deoxynucleotide, excision of purines being much less inhibited than that of pyrimidines. It does not depend on the purine or pyrimidine nature of the inhibitor.

In victims of Sudden Infant Death Syndrome, the activity of phenylethanolamine-N-methyltransferase was found to decrease in the nucleus retroambigu, the Kolliker-Fuse nucleus and the C 2 area of medulla, whereas a decrease in the dopamine-beta-hydroxylase activity was found only in the C 2 area. These results suggest a hypoactivity of adrenergic neurons in respiratory and cardiac centres in the Sudden Infant Death Syndrome.

The DNA sequences of three bacteriophages are analysed in order to localise those parts coding for a protein. A weak stability on the DNA molecule allows us to characterize the beginning and the end of genes. A survey of the codons used shows that the cause for this weak stability is the systematic use of A-T bases in third position, which is made possible by the degeneracy of the genetic code.