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.     

Andalusian astronomy: al-Zîj al-Muqtabis of Ibn al-Kammâd

Communicated by J. North     

The value of good Biozzi antibody-producing strains of mice for the production of monoclonal antibodies]

We report here that using Biozzi's high and low responder strains of Mice in the preparation of monoclonal antibodies against human T lymphocytes, we observed with the high responder strain 1) a higher number of hybrids; 2) a huge increase in the proportion of hybrids secreting on antibody directed against human lymphocytes.     

Suppressor effects and cyclic AMP accumulation by the CD29 molecule of CD4+ lymphocytes

Integrins are a superfamily of related molecules whose function, where known, is to mediate adhesion. The so-called very-late-activation antigen (VLA) family includes at least five distinct heterodimers, each composed of a unique alpha-subunit non-covalently associated with a common beta-subunit. Several members of the family have been shown to bind extracellular matrix proteins, but the function of VLA-4 is so far unknown. VLA-4 is the only member of the family detected on thymocytes and resting T cells. We show here that an antibody which recognizes the beta-subunit of VLA-4 (CD29) on T cells can inhibit CD4+ cell proliferation triggered by CD2 or CD3, and that binding of this antibody to activated T cells leads to an increase in cyclic AMP levels which is comparable to that elicited by forskolin. These negative signalling effects are unique to this antibody: other CD29 antibodies do not affect the growth of activated CD4 cells but enhance the proliferation of whole T cell populations and abrogate the suppressive effects of mitomycin-treated CD8 cells on CD4-cell growth. Taken together, our results indicate that VLA-4 functions in cell-cell interactions and that it is the target for the suppressive effects of CD8 cells on CD4 cells.     

Genome-wide atlas of gene expression in the adult mouse brain

Molecular approaches to understanding the functional circuitry of the nervous system promise new insights into the relationship between genes, brain and behaviour. The cellular diversity of the brain necessitates a cellular resolution approach towards understanding the functional genomics of the nervous system. We describe here an anatomically comprehensive digital atlas containing the expression patterns of approximately 20,000 genes in the adult mouse brain. Data were generated using automated high-throughput procedures for in situ hybridization and data acquisition, and are publicly accessible online. Newly developed image-based informatics tools allow global genome-scale structural analysis and cross-correlation, as well as identification of regionally enriched genes. Unbiased fine-resolution analysis has identified highly specific cellular markers as well as extensive evidence of cellular heterogeneity not evident in classical neuroanatomical atlases. This highly standardized atlas provides an open, primary data resource for a wide variety of further studies concerning brain organization and function.