Induction of endogenous murine C-type viruses. Attempt at discrimination by the pI of polypeptide p30 and the aspect of cellular transformation]

Endogenous ecotropic and xenotropic murine C-type viruses induced in K-Balb-3T3 cells treated with iododeoxyuridine (IdU) were selected by infection of appropriate indicator cells. The isoelectric point (p1) of the major viral polypeptide (p30) was found to be 6.1 for the ecotropic virus (class I), and 5.7 for the xenotropic virus (class II). An isoelectric form (iso p30) of pl 6.5 was observed in the initial induction peak. In addition, the pattern of cellular alteration in NRK cells at its onset varied according to the pseudotype, the class I pseudotype inducing round cell foci while the foci associated with the class II pseudotype consisted of fusiform cells.     

Attempt to alter antigenic structure of normal tissues by treatment with dimethyl-triazeno-imidazole-carboxamide in vivo

Summary The antigenic structure of normal skin and spleen cells has been investigated following in vivo treatment with the compound DIC. In experiments involving skin grafting in the normal and sensitized host, cross sensitization with a DIC-antigenic lymphoma and³H-thymidine incorporation by lymphocytes cultured with DIC-treated spleen cells, new antigens on DIC-treated tissues were not demonstrated.Research supported in part by Contract No. 74.00237.04 from C.N.R., Rome.We wish to thank Mr.C. R. Reeder of the Mammalian Genetics and Animal Production Section of NCI, NIH, Bethesda, Maryland, USA, for breeding and providing the animals, and Serpero Foundation, Milan, for support. The proficient technical assistance of Ms.C. Cattoi andD. Peroni is also acknowledged.     

Interconversion of T-2636 antibiotics produced byStreptomyces rochei var.volubilis

Zusammenfassung Mit angereicherten Enzympräparaten vonStreptomyces rochei var.volbulis sowie einigen Pilzen Hessen sich die Antibiotica T-2636 A (I) und D (III) zu C (II) beziehungsweise F (IV) reversibel desacetylieren. Die Antibiotica (III) und (IV) wurden auch mit dem EnzymS. rochei var.volubilis dehydriert.     

Flow microcalorimetric bioassay of polyene antibiotics: Interaction with growingSaccharomyces cerevisiae

Summary Microcalorimetric investigation of the interaction of polyene antibiotics with mid-exponential cells of a growing culture ofSaccharomyces cerevisiae has been used as the basis of a bioassay procedure. The assay is rapid, sensitive and reproducible. The results are compared to classical assays and potency ranking orders.This work was supported by the Science Research Council. (Studentship for B.Z. Chowdhry). We are grateful to the Central Research Fund of London University for funds to purchase the flow nephelometer used to support this study.