Several phylogenetic methods based on whole genome sequence data were evaluated using data from nine complete baculovirus genomes. The utility of three independent character sets was assessed. The first data set comprised the sequences of the 63 genes common to these viruses. The second set of characters was based on gene order, and phylogenies were inferred using both breakpoint distance analysis and a novel method developed here, termed neighbor pair analysis. The third set recorded gene content by scoring gene presence or absence in each genome. All three data sets yielded phylogenies supporting the separation of the Nucleopolyhedrovirus (NPV) and Granulovirus (GV) genera, the division of the NPVs into groups I and II, and species relationships within group I NPVs. Generation of phylogenies based on the combined sequences of all 63 shared genes proved to be the most effective approach to resolving the relationships among the group II NPVs and the GVs. The history of gene acquisitions and losses that have accompanied baculovirus diversification was visualized by mapping the gene content data onto the phylogenetic tree. This analysis highlighted the fluid nature of baculovirus genomes, with evidence of frequent genome rearrangements and multiple gene content changes during their evolution. Of more than 416 genes identified in the genomes analyzed, only 63 are present in all nine genomes, and 200 genes are found only in a single genome. Despite this fluidity, the whole genome-based methods we describe are sufficiently powerful to recover the underlying phylogeny of the viruses.

The nucleotide sequence of the DNA genome of Cydia pomonella granulovirus (CpGV) was determined and analysed. The genome is composed of 123 500 bp and has a GMC content of 45n2 %. It contains 143 ORFs of 150 nucleotides or more that show minimal overlap. Onehundred-and-eighteen (82n5 %) of these putative genes are homologous to genes previously identified in other baculoviruses. Among them, 73 are homologous to genes of Autographa californica nucleopolyhedrovirus (AcMNPV), whereas 108 and 98 are homologous to genes of Xestia c-nigrum GV (XcGV) and Plutella xylostella GV (PxGV), respectively. These homologues show on average 37n4 % overall amino acid sequence identity to those from AcMNPV and 45 % to those from XcGV and PxGV. The CpGV gene content was compared to that of other baculoviruses. Several genes reported to have major roles in baculovirus biology were not found in the CpGV genome, such as gp64, the major budded virus glycoprotein gene in some nucleopolyhedroviruses, and lef-7, involved in DNA replication. However, the CpGV genome encodes the large and small subunits of ribonucleotide reductase, three inhibitor of apoptosis (iap) homologues and two protein tyrosine phosphatases. The CpGV, PxGV and XcGV genomes present a noticeably high level of conservation of gene order and orientation. A striking feature of the CpGV genome is the absence of typical homologous repeat sequences. However, it contains one major repeat region and 13 copies of a single 73-77 bp imperfect palindrome.

Two types of alcohol dehydrogenase in separate protein families are the "medium-chain" zinc enzymes (including the classical liver and yeast forms) and the "shortchain" enzymes (including the insect form). Although the medium-chain family has been characterized in prokaryotes and many eukaryotes (fungi, plants, cephalopods, and verte-brates), insects have seemed to possess only the short-chain enzyme. We have now also characterized a medium-chain alcohol dehydrogenase in Drosophila. The developmental stages of the fly, compatible with the constitutive nature of the vertebrate enzyme. Taken together, the results bridge a previously apparent gap in the distribution of medium-chain alcohol dehydrogenases and establish a strictly conserved class m enzyme, consistent with an important role for this enzyme in cellular metabolism.The "classical" alcohol dehydrogenase is part of a widespread system of zinc-containing enzymes (1). In mammalian tissues, at least six classes of this enzyme occur. They differ considerably and represent stages between separate enzymes and ordinary isozymes. Class I is the well-known liver enzyme with ethanol dehydrogenase activity (2), class III is identical with glutathione-dependent formaldehyde dehydrogenase (3), class IV is a form preferentially expressed in stomach (4, 5), while classes II, V, and VI, although little studied, are known also to exhibit distinct properties (6, 7, 44). The class origins have been traced to gene duplications early in vertebrate evolution [the I/III duplication (8)] or during that evolution [the IV/I duplication (5)], with emerging activities toward ethanol (9); class III corresponds to an ancestral form. These properties and the different evolutionary patterns, with class III being "constant" and class I "variable" (10), result in a consistent picture of the enzyme system and place the classes of medium-chain alcohol dehydrogenases as separate enzymes in the cellular metabolism.Similarly, another protein family, short-chain dehydrogenases, has also evolved into a family comprising many different enzyme activities, including an alcohol dehydrogenase (11). This form operates by means of a completely different catalytic mechanism and is related to mammalian prostaglandin dehydrogenases/carbonyl reductase (12). Thus far, this alcohol dehydrogenase has been found in insects, the Drosophila enzyme being recognized early to differ from the zinc-containing alcohol dehydrogenases (13,14). Its properties in various Drosophila species are well established (15).These two alcohol dehydrogenase types demonstrate that ethanol dehydrogenase activity has evolved in different manners, with many organisms now employing a medium-chain enzyme, while others depend on a short-chain enzyme. The medium-chain family has not been identified in insects, although it is of ancient origin and has been characterized in other eukaryotes and in prokaryotes. We now show that the family is indeed present also in insects and that its major representative is the typical class III t...

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Sugar conjugation is a major pathway for the inactivation and excretion of both endogenous and exogenous compounds. We report here the molecular cloning and functional characterization of a phenol UDP-glucosyltransferase (UGT) from the silkworm, Bombyx mori, which was named BmUGT1. The complete cDNA clone is 1.6 kb, and the gene is expressed in several tissues of fifth-instar larvae, including fat body, midgut, integument, testis, silk gland and haemocytes. The predicted protein comprises 520 amino acids and has 30% overall amino-acid identity with other members of the UGT family. The most conserved region of the protein is the C-terminal half, which has been implicated in binding the UDP-sugar. BmUGT1 was expressed in insect cells using the baculovirus expression system, and a range of compounds belonging to diverse chemical groups were assessed as potential substrates for the enzyme. The expressed enzyme had a wide substrate specificity, showing activity with flavonoids, coumarins, terpenoids and simple phenols. These results support a role for the enzyme in detoxication processes, such as minimizing the harmful effects of ingested plant allelochemicals. This work represents the first instance where an insect ugt gene has been associated with a specific enzyme activity.

Several groups of large DNA viruses successfully utilise the rich resource provided by insect hosts. Defining the mechanisms that enable these pathogens to optimise their relationships with their hosts is of considerable scientific and practical importance, but our understanding of the processes involved is, as yet, rudimentary. Here we describe an informatics-based approach that uses comparison of viral genomic sequences to identify candidate genes likely to be specifically involved in this process. We hypothesise that such genes should satisfy two essential criteria, namely, that they should be (i) present in those members of a virus family that infect insects, but absent from those that infect other hosts, and (ii) found in at least two unrelated taxa of insect viruses. These criteria currently identify six groups of viral genes, including one that encodes the fusolin/gp37 proteins. Demonstration that the fusolin/gp37 proteins can enhance oral infectivity of insect viruses provides a primary validation of this approach to the examination of insect-virus relationships.

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The glutathione-dependent formaldehyde dehydrogenase gene (gfd) of Drosophila melanogaster encodes an enzyme that is active toward S-hydroxymethylglutathione, an adduct of formaldehyde with glutathione, and also with long-chain primary alcohols, both properties typical of class I11 alcohol dehydrogenases. gfd hybridizes at the 86D division of the third chromosome, in agreement with the known location of the Drosophila octanol dehydrogenase gene (odh). gfdlodh was isolated from a AEMBL-4 genomic library and consists of three exons (with coding segments of 21, 90 and 1029 bp) and two introns (69 bp and 70 bp, respectively). The introns are small in size like the Drosophila interrupting sequences and are located at the 5' end of the coding region. Comparisons with the homologous genes of Saccharomyces, Candida and humans provide information on the evolution of the class I11 alcohol dehydrogenases. Moreover, results from analysis of exodintron distributions in eleven dehydrogenases are compatible with the hypothesis of intron loss accounting for aspects of the present structure of these genes.Drosophila ethanol-active alcohol dehydrogenase (ADH) is a member of the short-chain dehydrogenaselreductase family (SDR), a group of enzymes which utilize a variety of substrates, such as alcohols, steroids, prostaglandins and ribito1 (Persson et al., 1991). Since these enzymes were first described (Ursprung and Leone, 1965), the Drosophila ADH has provided much information widely used by molecular biologists, geneticists and biochemists to answer fundamental questions concerning gene structure and enzyme evolution (Sullivan et a]., 1990;Heinstra, 1993). The ADH enzymes that are widespread in eukaryotic lineages that belong to another large family of medium-chain, zinc-containing enCorrespondence to R.