Oocytes of a single individual of Phallusia mammillata (Roscoff, France) were fertilized by a mixture of sperm of two individuals and development was followed microscopically. Embryos were snapfrozen in liquid nitrogen at the appropriate stage and kept at -80°C. Samples at stage 0, 8, 12, 15, 21, 26 were collected from the same fertilzation, while sample from stage 11 was independently collected from a different individual. Total RNA was prepared with the RNA II kit of Magerey Nagel and the quality was checked with the Bioanalyzer, all 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).

Lateral view of a 8-cell stage embryo stained with Delta2 (AHC0AAA62YG24_RM1). No expression was observed.

Animal view with anterior to the left of a 32-cell stage embryo stained with Delta2 (AHC0AAA62YG24_RM1). No expression was observed.

Animal view with anterior to the left and lateral view of a 64-cell stage embryo stained with Delta2 (AHC0AAA62YG24_RM1). Expression was observed in the b7.9 and b7.10 cell pair as well as the A7.6 cell pair.

Vegetal view with anterior to the left and lateral view with anterior to the left and animal to the top of a 112-cell stage embryo stained with Delta2 (AHC0AAA62YG24_RM1). Expression was observed in the b8.18, b8.20, A8.11 and A8.12 cell pairs.

Animal view of a 10-stage embryo stained with Delta2 (AHC0AAA62YG24_RM1).

Original annotation: In Phallusia mammillata embryos, Delta2 is expressed in b6.5 derivatives