In an effort to establish a suitable alternative to the widely used 18S rRNA system for molecular systematics of fungi, we examined the nuclear gene RPB2, encoding the second largest subunit of RNA polymerase II. Because RPB2 is a single-copy gene of large size with a modest rate of evolutionary change, it provides good phylogenetic resolution of Ascomycota. While the RPB2 and 18S rDNA phylogenies were highly congruent, the RPB2 phylogeny did result in much higher bootstrap support for all the deeper branches within the orders and for several branches between orders of the Ascomycota. There are several strongly supported phylogenetic conclusions. The Ascomycota is composed of three major lineages: Archiascomycetes, Saccharomycetales, and Euascomycetes. Within the Euascomycetes, plectomycetes, and pyrenomycetes are monophyletic groups, and the Pleosporales and Dothideales are distinct sister groups within the Loculoascomycetes. We confirm the placement of Neolecta within the Archiascomycetes, suggesting that fruiting body formation and forcible discharge of ascospores were characters gained early in the evolution of the Ascomycota. These findings show that a slowly evolving protein-coding gene such as RPB2 is useful for diagnosing phylogenetic relationships among fungi.

The surface antigens of hepatitis B virus (HBsAg) has been synthesized in the yeast Saccharomyces cerevisiae by using an expression vector that employs the 5'-flanking region of yeast alcohol dehydrogenase I as a promotor to transcribe surface antigen coding sequences. The protein synthesized in yeast is assembled into particles having properties similar to the 22-nm particles secreted by human cells.

An investigation of mushroom phylogeny using the largest subunit of RNA polymerase II gene sequences (RPB1) was conducted in comparison with nuclear ribosomal large subunit RNA gene sequences (nLSU) for the same set of taxa in the genus Inocybe (Agaricales, Basidiomycota). The two data sets, though not significantly incongruent, exhibit conflict among the placement of two taxa that exhibit long branches in the nLSU data set. In contrast, RPB1 terminal branch lengths are rather uniform. Bootstrap support is increased for clades in RPB1. Combined data sets increase the degree of confidence for several relationships. Overall, nLSU data do not yield a robust phylogeny when independently assessed by RPB1 sequences. This multigene study indicates that Inocybe is a monophyletic group composed of at least four distinct lineages-subgenus Mallocybe, section Cervicolores, section Rimosae, and subgenus Inocybe sensu Kühner, Kuyper, non Singer. Within subgenus Inocybe, two additional lineages, one composed of species with smooth basidiospores (clade I) and a second characterized by nodulose-spored species (clade II), are recovered by RPB1 and combined data. The nLSU data recover only clade I. The genera Astrosporina and Inocybella cannot be recognized phylogenetically. "Supersections" Cortinatae and Marginatae are not monophyletic groups.

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