The immediate-early (IE) protein Vmw175 (ICP4) of HSV-1 is required for the transcription of later classes of viral genes and the repression of IE gene expression. We have previously constructed a panel of plasmid-borne insertion and deletion mutants of the gene encoding Vmw175 and assayed their ability to regulate transcription in transient transfection assays. By this approach we have mapped the regions of the Vmw175 amino acid sequence that are required for transcriptional activation and repression of herpes virus promoters. This paper describes the use of nuclear extracts, made from cells transfected with these mutant plasmids, in gel retardation DNA binding assays in order to define the regions of Vmw175 involved in binding to a specific Vmw175 DNA binding site. The results show that amino acid residues 275-495 (a region which is highly conserved between Vmw175 and the varicella-zoster virus "IE" 140K protein) include structures which are critically required for specific DNA binding, transactivation and repression. This raises the interesting paradox that although the specific DNA sequence recognized by Vmw175 is not commonly found in its target promoters, the protein domain required for recognition of this sequence is required for promoter activation.

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Abstract.Biologists use scientific names to label the organisms described in their data; however, these names are not unique identifiers for taxonomic entities. Alternative taxonomic classifications may apply the same name, associated with alternative definition or circumscription. Consequently, labelling data with scientific names alone does not unambiguously distinguish between taxon concepts. Accurate integration and comparison of biological data is required on taxon concepts, as defined in alternative taxonomic classifications. We have derived an abstract, inclusive model for the diverse representations of taxonomic concepts used by taxonomists and in taxonomic databases. This model has been implemented as a proposed standard XML schema for the exchange and comparison of taxonomic concepts between data providers and users. The representation and exchange of taxon definitions conformant with this schema will facilitate the development of taxonomic name/concept resolution services, allowing the meaningful integration and comparison of biological datasets, with greater accuracy than on the basis of name alone.

like elements have two open reading frames. In each Edinburgh EH9 3JR, UK case the second of these appears to encode a reverse 1 Corresponding author transcriptase Mathias et al., 1991). et al., 1984;Fawcett et al., 1986) sequence encoded by the first of these, ORF1, includes that was identified because it is responsible for a form the motif CX 2 CX 4 HX 4 C that is characteristic of the of hybrid dysgenesis (Finnegan, 1989; Bucheton, 1990) nucleocapsid domain of retroviral gag polypeptides Strains of D.melanogaster can be classified as being either followed by a copy of the slightly different sequences inducer or reactive depending on whether or not they CX 2 CX 4 HX 6 C and CX 2 CX 9 HX 6 C. The function of this contain active I factors in their chromosomes. The female protein is unknown. We have expressed this protein in progeny from crosses between inducer males and reactive Escherichia coli and Spodoptera frugiperda cells and females are abnormal, showing reduced fertility and have shown that it binds both DNA and RNA but increased frequencies of germ-line mutations, a phenomwithout any evidence for sequence specificity. The enon know as I-R hybrid dysgenesis. This is associated properties of deletion derivatives of the protein indicate with a greatly increased frequency of I factor transposition. that more than one region is responsible for DNA The male progeny from such a cross are normal, as are binding and that the CCHC motif is not essential for the progeny of crosses between reactive males and inducer this. The ORF1 protein expressed in either E.coli or females (Finnegan, 1989; Bucheton, 1990). Spodoptera cells forms high molecular weight structuresThe open reading frames of the I factor are 1287 bp that require the region of the protein including the (ORF1) and 3675 bp (ORF2) long and are separated by CCHC motif for their formation. This protein can 53 bp. The amino acid sequence encoded by ORF2 also accelerate the annealing of complementary singlecontains reverse transcriptase and RNaseH domains similar stranded oligonucleotides. These results suggest that to those found in retroviral pol genes (Fawcett et al., this protein may associate with the RNA transposition 1986) and other LINE-like transposable elements, while intermediates of the I factor to form particles that that of ORF1 has a copy of the motif CX 2 CX 4 HX 4 C enter the nucleus during transposition and that it may (CCHC) similar to those in the basic nucleocapsid portion stimulate both the priming of reverse transcription of retroviral gag polyproteins (Berg, 1990) and the coat and integration. This may be generally true for the protein of cauliflower mosaic virus (Franck et al., 1980

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