BOTRYLLUS SCHLOSSERI BLASTOGENETIC CYCLE: GENE EXPRESSION ANALYSIS USING SOLID SEQUENCING TECHNOLOGY

BOTRYLLUS SCHLOSSERI BLASTOGENETIC CYCLE: GENE EXPRESSION ANALYSIS USING SOLID SEQUENCING TECHNOLOGY Fabio Gasparini, Davide Campagna, Nicola Franchi, Giorgio Valle, Lucia Manni, Loriano Ballarin Diparlimento di Biologia, Universita degli Studi di Padova. fabio.gasparini@unipd.it Colonies of the cosmopolitan ascidian Botryllus schlosseri are formed by zooids arranged in star-shaped systems, of 6-12 individuals around a common cloacal opening. They undergo cyclical generation change or take-over, during which tissues of adult zooids undergo massive apoptosis, are progressively resorbed and replaced by their buds which reach functional maturity and start filtering. The interest towards the Botryllus blastogenetic cycle has recently increased as it represents a reliable model for the study of natural apoptosis during the generation change and asexual reproduction by continuous budding. The recent development of high-throughput sequencing technologies allow the expanding of the range of the studied organisms and was applied to many model organisms for the discovery of splice variants, RNA editing sites and new microRNA. The production of a de novo transcriptome assembly is often the preferred method for the study of non-model organisms, since it is cheaper and easier than constructing a genome. We have sequenced several SOLID RNA-seq libraries coming from 3 stages of the colonial blastogenetic cycle: i) the phase immediately preceding the take-over, when the colony is preparing to the generation change; ii) the take-over, when adult zooids are resorbed and replaced by new ones, and iii), the mid-cycle phase, when buds and zooids coexist together and no generation change occurs. RNA-seq data has allowed the production of a de nova transcriptome assembly for B. schlosseri and all information has been included in an ad hoc database which interacts with a Web based interface. As resulting by gene expression analysis we have found several differentially expressed genes putatively responsible of the morphological and biochemical changes during blastogenesis. This result opens new research perspectives for the study of the interplay between death and life during the generation change as well as the regulation of asexual reproduction in B. schlosseri.