H. G. Schweiger Knihy

General aspects of nucleic acid uptake by mammalian cells have been the subject of several reviews during the last few years (PAGANO, 1970; BHARGAVA and SHANMUGAM, 1971; DUBES, 1971; RYSER, 1967). These reviews covered methods used for the infection of cells by viral nucleic acids as well as interaction of mammalian cells with non-viral nucleic acids. This article is restricted to a discussion of experiments with poliovirus RNA and focuses special attention on the steps following the uptake of RNA into a cell, aspects that were not discussed in earlier review articles. The fate of input RNA once inside the cell is determined by the host cell but experimental conditions can be chosen to favor the survival of input RNA and the induction of a virus growth cycle by interfering with host-cell meta­ bolism through events that, in the case of infection with intact virus, might be controlled by viral proteins.

Several discoveries are noteworthy for allowing us to probe the recesses of the virus­ infected cell and to search for cryptic viral genomes which might provide clues in our studies of cancer etiology or developmental biology. One of the most notable was the dis­ covery of reverse transcriptase. This marked a momentous occasion in the history of molecular biology. Not only did it provide insight into the mechanism of persistence of retroviruses but it also provided us with an enzyme that could synthesize a DNA copy of any RNA. This DNA copy could then be used as a hybridization reagent to search for both complementary DNA and viral-specific RNA. Thus one could follow the course of any viral infection or probe in tumor cells for hidden viral genomes. Second, a great deal of credit must be given to the geneticists who isolated the various deletion mutants in the 'avian retrovirus system and thus provided us with the frrst means of isolating gene-spe­ cific probes. Finally, the laboratories which have mapped the genome have provided us with the framework in which to ask very specific questions with our gene-specific probes. Recently, numerous excellent reviews concerning various aspects of the retroviruses have appeared. In this review I shall not even attempt to present a comprehensive review of retroviruses.

In September, 1976, the International Federation for Cell Biology held its first congress in Boston. On this occasion Berlin was chosen as the site for the next congress. This meant an acknowledgement and at the same time a heavy burden for the still young European Cell Biology Organization, which repre sents a junction of European societies and groups for cell biology. In practical terms, this meant that the members of the young and, compared to the Ame rican Society for Cell Biology, small German Society for Cell Biology had to do a good deal of the organizing of the Cell Biology Congress. This is an op portunity for me, as Chairman of the Organizing Committee, and also on be half of the German Society for Cell Biology, to express my gratitude to all those who have actively participated in the preparations for this Cell Biology Congress. The success of the Congress in Berlin was to a significant extent due to their work. In particular, I would like to especially thank the Secretary General ofECBO Werner Franke, Heidelberg, as well as the Chairman of the Local Organizing Committee, Peter Giesbrecht, Berlin, for the excellent job they did. The Congress in Berlin proved to be significantly larger than that in Boston in 1976. The number of abstracts increased from 1200 to more than 1800. They have been published in the European Journal of Cell Biology. In a simi lar way the number of symposia and workshops expanded.