Oocytes of a single individual of Halocynthia roretzi (Aomori, Japan) were fertilized by sperms of an another single individual and development was followed microscopically. Embryos were snapfrozen in liquid nitrogen at the appropriate stage and kept at -80°C. Total RNA was prepared with the AGPC method and the quality was checked with the Bioanalyzer, most samples had a RIN value of higher than 9. Strand specific libraries were constructed and the sequencing (50PE) was performed with Illumina HiSeq 2000 technology (BGI, Hong Kong, China).

Halocynthia roretzi 8-cell stage embryo probed for SoxB1 expression.
Zygotic transcription is detected in the somatic, but not in the germline lineage. SoxB1 mRNA is stained Dark blue or brown. Anterior is to the left. Lateral view.

Halocynthia roretzi 32-cell stage embryo probed for SoxB1 expression.
Zygotic transcription is detected in the somatic, but not in the germline lineage. SoxB1 mRNA is stained Dark blue or brown. Anterior is to the top. Lateral view.

SoxB1 zygotic transcription is detected in the somatic, but not in the germline lineage. SoxB1 mRNA is stained Dark blue or brown. PEM mRNA is stained red for identification of germline cells. Anterior is to the top. Vegetal view.

Vegetal view of a Halocynthia roretzi 32-cell stage embryo probed for SoxB1 expression and injected with control YFP mRNA. SoxB1 is observed in the A-line.

SoxB1 zygotic transcription is detected in the somatic, but not in the germline lineage. SoxB1 mRNA is stained Dark blue or brown. PEM mRNA is stained red for identification of germline cells. Anterior is to the top. Vegetal view.

Vegetal view of a Halocynthia roretzi 32-cell stage embryo probed for SoxB1 expression and injected with control YFP mRNA. SoxB1 is observed in the A-line.