Rodica Emanoil-Ravier

Purification and Characterization of the Major Envelope Glycoprotein of Simian Foamy Virus Type 1

Simian foamy virus type 1 (SFV-1), the prototype of the Spumavirinae, was subjected to disruption and serial purification procedures. Separation of SFV-1 envelope components from viral cores was verified by electron microscopy, density gradient centrifugation and polyacrylamide gel electrophoresis. After affinity chromatography of the envelope polypeptides on a concanavalin A-Sepharose column, a highly purified 70 000 mol. wt. protein was recovered. Glycosylation of this gp70 was confirmed by glucosamine labelling. Immunological studies with anti-SFV antisera confirmed the type-specificity of this envelope gp70.

Simultaneous activation by 5-azacytidine of intracisternal R particles and murine intracistemal-A particle related sequences in syrian hamster cells

5-Azacytidine treatment of Syrian hamster (Mesocricetus auratus) cells, BHK21-cl.13, and primary embryo fibroblasts, activates the production of intracisternal type R particles (IRP) as ascertained by electron microscopy scanning and counting. Efficiency of the activation is dose- and time of treatment-dependent. The transcription of mouse intracisternal A particle (IAP) related sequences, which have been described in Syrian hamster genomic DNA, is increased at the same time. This correlates with demethylation of hamster IAP related genes, as shown by restriction of high molecular weight DNA from 5-azacytidine treated cells with methylation sensitive enzymes, and subsequent electrophoresis and molecular hybridization of the fragments with specific DNA probes. In 5-azacytidine treated cells derived from other hamster species (Cricetulus griseus and C. migratorius), intracisternal R particles were not induced, nor were mouse IAP-related RNAs detected.

Amplification and rearrangement of Ki-ras oncogene in human teratocarcinoma-derived cell lines

The structure of the ras gene family was analyzed in two human teratocarcinoma-derived cell lines, Tera I and Tera II, by DNA restriction enzyme digestion and Southern blot. We report here a ten-fold amplification of the c-Ki-ras-2 gene in these cell lines, whereas no structural alterations seem to occur either in c-Ha-ras-1 or N-ras. We also provide evidence indicating that no point mutation at codon 12, specifically recognized by Sac I, was detected. Moreover, DNA rearrangement, due to the loss of a Pvu II site located in the intervening sequences between the third and the fourth exon, has been found in both Tera I and Tera II.

Studies on four cellular proto-oncogenes and their expression in PCC4 embryonal carcinoma cells: amplification of c-Ki-ras oncogene.

We examined the expression of four cellular proto-oncogenes in two teratocarcinoma cell lines, one undifferentiated and malignant (PCC4), one differentiated and non malignant (PCD1). In this paper we report that transcript levels of c-Ki-ras, c-myc and c-fos are significantly higher in PCC4 cells whereas transcripts of c-Ha-ras are unchanged. Southern blot analysis does not reveal any structural alteration of c-myc and c-fos in PCC4 cells. On the contrary, the c-Ki-ras proto-oncogene is amplified 10 to 20 fold in PCC4 cells.

Molecular cloning and characterization of retrovirus-like intracisternal type A particle genes (IAP) present in the Chinese hamster genome

Endogenous retrovirus-like sequences that are homologous to the multigenic murine and Syrian hamster intracisternal type A particle (IAP) genes can be detected in very few copies in the Chinese hamster (CH) genome. They were cloned from a CHO gene library and two recombinants, harboring the major IAP-like DNA genes characterized by Southern blot hybridization after DNA digestion with several restriction enzymes. The IAP DNA inserts of the two clones analyzed were 4.70 and 8.04 kb respectively, allowing us to construct a physical map of our Chinese hamster clone that represents an almost complete IAP element.