MSc Student
Advisor: Tim Wollesen

Unit for Integrative Zoology, Department of Evolutionary Biology
University of Vienna

Abstract

Chaetognaths are marine predators that are part of the zooplankton in oceans. After hatching they develop directly into their adult form without a prior larval stage, with some organs such as the brain still developing, while other portions of the nervous system, like the ventral nerve centre are already almost matured. Their phylogenetic position is still highly debated and they have been hypothesized to be either deuterostomes, a basal offshoot of protostomes, belonging to a sister group to Lophotrochozoans or being the sister taxon to Gnathiferans. So far the role of micro RNAs (miRNAs) has not been studied in detail in spiralians, so we took the chance to investigate.

But what exactly is a miRNA? Mature miRNAs are ~22 nucleotide long non-coding RNAs that sculpt the transcriptome by posttranscriptional repression. Many miRNAs are highly conserved and their sequences are similar in all metazoans. MiRNAs also readily emerge and are linked to the evolution of body plan complexity in animals. This conservation and emergence make them a great tool for phylogenetic analysis.

By looking at the miRNA repertoire of the chaetognath Spadella cephaloptera, we hope to find out more about their role during early body plan formation and by comparing expression patterns of certain highly conserved miRNAs with animals from lophotrochozoan taxa such as polyplacophoran mollusks and entoprocts, we help to elucidate which role these miRNAs played during the body plan formation of the last common bilaterian ancestor.