Monoubiquitination of H2BK123 (H2BK123ub), catalyzed by Rad6/Bre1, is a transient histone modification with roles in transcription and is essential for establishing H3K4 and H3K79 trimethylations (H3K4me3 and H3K79me3). Here, we investigated the chromatin network around H2BK123ub by examining its localization and co-occurrence with its dependent marks as well as the transcription elongation mark H3K36me3 across the genome of Saccharomyces cerevisiae. In yeast, H2BK123ub is removed by the deubiquitinases Ubp8 and Ubp10, but their genomic target regions remain to be determined. Genome-wide maps of H2BK123ub in the absence of Ubp8 and Ubp10 revealed their distinct target loci, which were genomic sites enriched for H3K4me3 and H3K79me3, respectively. We propose an extended model of the H2BK123ub cross-talk by integrating existing relationships with the substrate specificities of Ubp8 and Ubp10 reported here.

In this paper, we describe an application, PubCloud that uses tagclouds for the summarization of results from queries over thePubMed database of biomedical literature. PubCloud responds toqueries of this database with tag clouds generated from wordsextracted from the abstracts returned by the query. The results ofa user study comparing the PubCloud tag-cloud summarization ofquery results with the standard result list provided by PubMedindicated that the tag cloud interface is advantageous in presenting descriptive information and in reducing user frustrationbut that it is less effective at the task of enabling users to discoverrelations between concepts.