Contrasting the development of larval and adult body plans during the evolution of biphasic lifecycles in sea urchins.

Biphasic lifecycles are widespread among animals, but little is known about how the developmental transition between larvae and adults is regulated. Sea urchins are a unique system for studying this phenomenon because of the stark differences between their bilateral larval and pentaradial adult body plans. Here, we use single-cell RNA sequencing to analyze the development of Heliocidaris erythrogramma (He), a sea urchin species with an accelerated, non-feeding mode of larval development.

Diverse somatic Transformer and sex chromosome karyotype pathways regulate gene expression in Drosophila gonad development.

The somatic sex determination gene () is required for the highly sexually dimorphic development of most somatic cells, including those of the gonads. In addition, somatic is required for the germline development even though it is not required for sex determination within germ cells. Germ cell autonomous gene expression is also necessary for their sex determination.