Primordial germ cell (PGC) specification occurs early in development.PGC specifiers have been identified in Drosophila, mouse, and human but remained elusive in most animals.Here we identify the RNA-binding protein Dnd as a critical PGC specifier in the medaka fish (Oryzias latipes).Dnd depletion specifically abolished PGCs, and its butter silk sarees pothys overexpression boosted PGCs.We established a single-cell culture procedure enabling lineage tracing in vitro.
We show that individual blastomeres from cleavage embryos at the 32- and 64-cell stages are capable of PGC production in culture.Importantly, Dnd overexpression increases PGCs via increasing PGC precursors.Strikingly, dnd RNA forms prominent particles that segregate asymmetrically.Dnd concentrates in germ plasm and stabilizes germ plasm RNA.Therefore, Dnd is a critical specifier of fish PGCs and utilizes particle partition as a previously unidentified mechanism for asymmetric segregation.
These findings offer insights into PGC specification and manipulation in chewmax pet products chicken feet natural chew dog treats medaka as a lower vertebrate model.