Le genisteto-carlinetum macrocephalae ass. nov. De l'étage montagnard et le ligusticetum corsici ass. nov. De l'étage subalpin des massifs du cinto et du campotile orientale

Sans résuméJe tiens à remercier M. le Dr. J. Braun-Blanquet de la généreuse hospitalité qu'il m'a offerte à la S.I.G.M.A. et des précieux conseils qu'il m'a dispensés pour la définition de ces associations. C'est la raison pour laquelle il m'a paru nécessaire de l'associer à l'une des Associations originales que j'ai décrites.Je suis également reconnaissant à mes amis M. et G. Roux d'avoir permis le traitement de mes données floristiques par l'analyse factorielle des correspondances.     

Le Genisteto-Carlinetum macrocephalae ass. nov. de l'étage montagnard et le Ligusticetum corsici ass. nov. de l'étage subalpin des Massifs du Cinto et du Campotile orientale

Sans résuméJe tiens à remercier M. le Dr.J. Braun-Blanquet de la généreuse hospitalité qu'il m'a offerte à la S.I.G.M.A. et des précieux conseils qu'il m'a dispensés pour la définition de ces associations. C'est la raison pour laquelle il m'a paru nécessaire de l'associer à l'une des Associations originales que j'ai décrites.Je suis également reconnaissant à mes amisM. et G. Roux d'avoir permis le traitement de mes données floristiques par l'analyse factorielle des correspondances.     

Immunoglobulin synthesis and glucose-6-phosphate dehydrogenase as cell markers in human lymphoblastoid cell lines

Multiple lymphoblastoid cell lines were established from each of seven Burkitt lymphoma biopsies and from tonsils, removed from four patients with chronic tonsillitis. The cellular origin of the lines was studied using as markers the pattern of immunoglobulins secreted into the medium and the cells' glucose-6-phosphate dehydrogenase (G-6-PD) phenotypes.Lines from the same tonsil biopsy differed from each other by their patterns of immunoglobulin synthesis and G-6-PD phenotypes. All tonsil-derived lines secreted complete immunoglobulins. Newly established lines usually produced several heavy and light chain types, indicating multicellular origin, but the number of components produced decreased during the course of long-term cultivation. G-6-PD phenotypes of lines established from the same tonsil removed from a G-6-PD heterozygote differed—B, A and B/A phenotypes were found. The B/A lines rapidly changed to a single enzyme phenotype (B or A) when maintained in culture.The immunoglobulin and G-6-PD phenotypes in lines derived from Burkitt lymphomas differed from those of tonsil lines in several respects: (1) Some lines produced no immunoglobulins; (2) in immunoglobulin-synthesizing lines, the patterns of heavy and light chain production were more restricted than in tonsil lines; (3) after some months in culture, a uniform pattern of immunoglobulin synthesis was found in all lines derived from the same tumour; (4) lines from G-6-PD heterozygotes had the same single enzyme phenotypes as were found in the tumours.The data strongly suggest that most lines from Burkitt lymphomas are derived from the tumour clones and that most tonsil-derived lines have multicellular origin.     

THE DIFFERENTIAL SENSITIVITY OF CULTURED CHICK MESODERMAL CELLS TO ACTINOMYCIN D

Cells were isolated from the somite mesoderm and from the unsegmented (presomite) mesoderm of early chick embryos and exposed to actinomycin D in single cell culture. Actinomycin D inhibited proliferation in cell cultures derived from the unsegmented mesoderm, although the same concentrations of this antibiotic did not inhibit cultures derived from the somite mesoderm. This differential sensitivity parallels the regionally specific necrosis and degeneration observed in the unsegmented mesoderm of intact chick embryos exposed to actinomycin D. In culture, both cell types exhibited approximately the same permeability to labeled actinomycin D and showed comparable inhibition of RNA, DNA, and protein syntheses in the presence of the antibiotic. However, freshly isolated mesodermal cells from the somite region had a higher content of RNA than did cells from the unsegmented region, and the somite cells maintained a higher rate of macromolecular synthesis in untreated cultures.     

Evaluation of Factors Related to Growth of Rift Valley Fever Virus in Suspended Cell Cultures

The effect of several controlled variables on the peak titer and fold increase of Rift Valley fever virus grown in suspension culture on two variants of Earle's L cell, L-DR and L-MA clone 1-1, was studied. No significant amount of cell-associated virus was found at 24 hr, indicating a release of virus soon after its formation. Mild sonic treatment of the virus produced in serum-free medium increased the infective titer about 10x. This difference was not observed with virus produced in medium supplemented with serum. Peak titer was not affected by medium used during the infection period, by multiplicity of inoculum (MOI), or by initial cell concentration within the test range of 10(4) to 2 x 10(6) cell/ml. Cell strain employed influenced titer, because the L-DR cell did not produce virus efficiently at low MOI and low initial cell concentration. The time of peak titer and fold replication was dependent on MOI and initial cell concentration. Differences in virus propagation in monolayer and suspension systems are discussed.