Tools for gene-regulatory analyses in the marine annelid Platynereis dumerilii.

The advent of high-throughput sequencing technology facilitates the exploration of a variety of reference species outside the few established molecular genetic model systems. Bioinformatic and gene expression analyses provide new ways for comparative analyses between species, for instance, in the field of evolution and development. Despite these advances, a critical bottleneck for the exploration of new model species remains the establishment of functional tools, such as the ability to experimentally express genes in specific cells of an organism. We recently established a first transgenic strain of the annelid Platynereis, using a Tc1/mariner-type Mos1 transposon vector. Here, we compare Mos1 with Tol2, a member of the hAT family of transposons. In Platynereis, Tol2-based constructs showed a higher frequency of nuclear genome insertion and sustained gene expression in the G0 generation. However, in contrast to Mos1-mediated transgenes, Tol2-mediated insertions failed to retain fluorescence in the G1 generation, suggesting a germ line-based silencing mechanism. Furthermore, we present three novel expression constructs that were generated by a simple fusion-PCR approach and allow either ubiquitous or cell-specific expression of a reporter gene. Our study indicates the versatility of Tol2 for transient transgenesis, and provides a template for transgenesis work in other emerging reference species.