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Physarum polycephalum is a well-studied microbial eukaryote with unique experimental attributes relative to other experimental\ud model organisms. It has a sophisticated life cycle with several distinct stages including amoebal, flagellated, and plasmodial cells. It is\ud unusual in switching between open and closed mitosis according to specific life-cycle stages. Here we present the analysis of the\ud genome of this enigmatic and important model organism and compare it with closely related species. The genome is littered with\ud simple and complex repeats and the coding regions are frequently interrupted by introns with a mean size of 100 bases.\ud Complemented with extensive transcriptome data, we define approximately 31,000 gene loci, providing unexpected insights into\ud earlyeukaryoteevolution.Wedescribeextensiveuseofhistidinekinase-basedtwo-componentsystemsandtyrosinekinasesignaling,\ud the presence of bacterial and plant type photoreceptors (phytochromes, cryptochrome, and phototropin) and of plant-type pentatricopeptide\ud repeat proteins, as well as metabolic pathways, and a cell cycle control system typically found in more complex eukaryotes.\ud Our analysis characterizes P. polycephalum as a prototypical eukaryote with features attributed to the last common ancestor of\ud Amorphea, that is, the Amoebozoa and Opisthokonts. Specifically, the presence of tyrosine kinases inAcanthamoeba and Physarum\ud as representatives of two distantly related subdivisions ofAmoebozoa argues against the later emergence of tyrosine kinase signaling\ud in the opisthokont lineage and also against the acquisition by horizontal gene transfer

The laboratory rat is one of the most extensively studied model organisms. Inbred laboratory rat strains originated from limited Rattus norvegicus founder populations, and the inherited genetic variation provides an excellent resource for the correlation of genotype to phenotype. Here, we report a survey of genetic variation based on almost 3 million newly identified SNPs. We obtained accurate and complete genotypes for a subset of 20,238 SNPs across 167 distinct inbred rat strains, two rat recombinant inbred panels and an F2 intercross. Using 81% of these SNPs, we constructed high-density genetic maps, creating a large dataset of fully characterized SNPs for disease gene mapping. Our data characterize the population structure and illustrate the degree of linkage disequilibrium. We provide a detailed SNP map and demonstrate its utility for mapping of quantitative trait loci. This community resource is openly available and augments the genetic tools for this workhorse of physiological studies. This work was supported by European Union grants LSGH-2004-005235 and LSHG-CT-2005-019015. D.G. is supported by a Wellcome Trust Senior Fellowship in Basic Biomedical Science (057733/Z/99/A). M.-T.B. and D.G. acknowledge support from the Wellcome Cardiovascular Functional Genomics Initiative (066780/Z/01/Z)

Background Subtle alternative splicing events involving tandem splice sites separated by a short (2-12 nucleotides) distance are frequent and evolutionarily widespread in eukaryotes, and a major contributor to the complexity of transcriptomes and proteomes. However, these events have been either omitted altogether in databases on alternative splicing, or only the cases of experimentally confirmed alternative splicing have been reported. Thus, a database which covers all confirmed cases of subtle alternative splicing as well as the numerous putative tandem splice sites (which might be confirmed once more transcript data becomes available), and allows to search for tandem splice sites with specific features and download the results, is a valuable resource for targeted experimental studies and large-scale bioinformatics analyses of tandem splice sites. Towards this goal we recently set up TassDB (Tandem Splice Site DataBase, version 1), which stores data about alternative splicing events at tandem splice sites separated by 3 nt in eight species. Description We have substantially revised and extended TassDB. The currently available version 2 contains extensive information about tandem splice sites separated by 2-12 nt for the human and mouse transcriptomes including data on the conservation of the tandem motifs in five vertebrates. TassDB2 offers a user-friendly interface to search for specific genes or for genes containing tandem splice sites with specific features as well as the possibility to download result datasets. For example, users can search for cases of alternative splicing where the proportion of EST/mRNA evidence supporting the minor isoform exceeds a specific threshold, or where the difference in splice site scores is specified by the user. The predicted impact of each event on the protein is also reported, along with information about being a putative target for the nonsense-mediated decay (NMD) pathway. Links are provided to the UCSC genome browser and other external resources. Conclusion TassDB2, available via http://www.tassdb.info, provides comprehensive resources for researchers interested in both targeted experimental studies and large-scale bioinformatics analyses of short distance tandem splice sites.

TG dinucleotides functioning as alternative 3' splice sites were identified and experimentally verified in 36 human genes., Background Despite some degeneracy of sequence signals that govern splicing of eukaryotic pre-mRNAs, it is an accepted rule that U2-dependent introns exhibit the 3' terminal dinucleotide AG. Intrigued by anecdotal evidence for functional non-AG 3' splice sites, we carried out a human genome-wide screen. Results We identified TG dinucleotides functioning as alternative 3' splice sites in 36 human genes. The TG-derived splice variants were experimentally validated with a success rate of 92%. Interestingly, ratios of alternative splice variants are tissue-specific for several introns. TG splice sites and their flanking intron sequences are substantially conserved between orthologous vertebrate genes, even between human and frog, indicating functional relevance. Remarkably, TG splice sites are exclusively found as alternative 3' splice sites, never as the sole 3' splice site for an intron, and we observed a distance constraint for TG-AG splice site tandems. Conclusion Since TGs splice sites are exclusively found as alternative 3' splice sites, the U2 spliceosome apparently accomplishes perfect specificity for 3' AGs at an early splicing step, but may choose 3' TGs during later steps. Given the tiny fraction of TG 3' splice sites compared to the vast amount of non-viable TGs, cis-acting sequence signals must significantly contribute to splice site definition. Thus, we consider TG-AG 3' splice site tandems as promising subjects for studies on the mechanisms of 3' splice site selection.