In recent years, it has become clear that, in addition to the regulation of the expression of specific genes, there are global regulatory systems that control the simultaneous expression of a large number of genes in response to a variety of environmental stresses. The first of these global control systems, and of substantial importance, is the heat-shock response. The heat-shock response is ch...

An infectious virus isolated from the cultured Drosophila melanogster cell line, Schneider 2-L, appears to be a member of a new group of animal viruses. The virus, HPS-1 has a genome composed of a single segment of double-stranded RNA approximately 6 kb in length. Virions are particles approximately 36 nm in diameter. They contain only two proteins and no lipid coat. The major protein, presumab...