Project description:Recent ChIP experiments indicate that spliceosome assembly and splicing can occur cotranscriptionally in S. cerevisiae. However, only a few genes have been examined, and all have long second exons. To extend these studies, we analyzed intron-containing genes with different second exon lengths, by ChIP as well as by whole-genome tiling arrays (ChIP-CHIP). The data indicate that U1 snRNP recruitment is independent of exon length. Recursive splicing constructs, which uncouple U1 recruitment from transcription, suggest that cotranscriptional U1 recruitment contributes to optimal splicing efficiency. In contrast, U2 snRNP recruitment as well as cotranscriptional splicing is deficient on short second exon-genes. We estimate that approximately 90% of endogenous yeast splicing is post-transcriptional, consistent with an analysis of post-transcriptional snRNP-associated pre-mRNA. Keywords: ChIP-CHIP
Project description:Species within nearly all extant animal lineages are capable of regenerating body parts. However, it remains unclear whether the gene expression programme controlling regeneration is evolutionarily conserved. Brittle stars are a species-rich class of echinoderms with outstanding regenerative abilities, but investigations into the genetic bases of regeneration in this group have been hindered by the limited available genomic resources. Here, we report a chromosome-scale genome assembly for the brittle star Amphiura filiformis. We show that the brittle star displays the most rearranged genome amongst echinoderms sequenced to date, featuring a reorganised Hox cluster reminiscent of the rearrangements observed in sea urchins. In addition, we performed an extensive profiling of gene expression throughout brittle star adult arm regeneration and identified sequential waves of gene expression governing wound healing, proliferation and differentiation. We conducted comparative transcriptomic analyses with other invertebrate and vertebrate models for appendage regeneration and uncovered hundreds of genes with conserved expression dynamics, notably during the proliferative phase of regeneration. Our findings emphasise the crucial importance of echinoderms to detect long-range expression conservation between vertebrates and classical invertebrate regeneration model systems.