Antonia Grausgruber
PhD Student(Advisor: Andreas Wanninger)
at the Department of Evolutionary Biology, Unit for Integrative Zoology 

Investigating transcriptomic foundations of developmental arrest in a vermetid gastropod
Antonia Grausgruber, Department of Evolutionary Biology, University of Vienna
Andreas Wanninger, Department of Evolutionary Biology, University of Vienna 

Abstract

Despite its curious adult appearance, early development of the caenogastropod worm snail Thylaeodus rugulosus (Vermetidae) follows a conserved, gastropod-typical indirect development including trochophore and veliger larval stages.  However, what appears common on a morphogenetic level, is controlled by a complex mechanism of brood regulation in early development. Until the late veliger stage Thylaeodus develops inside of maternal brooding capsules. Several capsules are attached inside the mother’s shell, each containing a multitude of embryos. But only a rather small percentage of the embryos within one capsule develops until the larval phase. Most embryos remain in a multicellular pre-blastula stage and serve as nutritive resource for their viable siblings which develop into early larvae. The production of such nutritive embryos or eggs is not uncommon in marine gastropods. In Thylaeodus rugulosus, however, developmental arrest can also happen later in larval development. Only a maximum of two to three animals per brooding capsule complete their development until hatching, while remaining siblings appear to get arrested in a stage that morphologically corresponds to the early veliger larva  . All these particularities make the development of Thylaeodus multilayered and complex, the underlying molecular and developmental mechanisms defining this developmental arrest remaining not understood to date. The current project aims at unravelling transcriptomic differences that shape the distinction between viable and arrested animals in Thylaeodus rugulosus by applying differential gene expression analysis on stage-specific transcriptomes. Comparing these differential expression data will allow for insights into the genetic toolkit that determines developmental arrest versus regular embryonic and larval development in these elusive gastropod mollusks.