Kogure, Y. S.; Hotta, K.

The invasive ascidian Ascidiella aspersa is known to be globally distributed (Muller, 1776) and characterized by its ultra-transparent embryos (Shito et al., 2021), which are ideal for studies of developmental biology and bioimaging. However, its use as a model organism has been limited due to the exceptionally low fertilization rate of dechorionated eggs. In this study, we present a new fertilization protocol that drastically increases the fertilization rate from below 10% to 80%, allowing for synchronously developing embryos without polyspermy. This protocol promotes the adoption of ascidian Ascidiella aspersa as a new chordate model in developmental biology.