lack the critical sperm factor PLCζ.

Fertilization of eggs from the African clawed frog is characterized by an increase in cytosolic calcium, a phenomenon that is also observed in other vertebrates such as mammals and birds. During fertilization in mammals and birds, the transfer of the soluble PLCζ from sperm into the egg is thought to trigger the release of calcium from the endoplasmic reticulum (ER). Injecting sperm extracts into eggs reproduces this effect, reinforcing the hypothesis that a sperm factor is responsible for calcium release and egg activation. Remarkably, this occurs even when sperm extracts from are injected into mouse eggs, suggesting that mammals and share a sperm factor. However, lacks an annotated gene, which encodes the PLCζ enzyme. In this study, we attempted to determine whether sperm from express an unannotated ortholog. We identified orthologs in 11 amphibian species, including 5 that had not been previously characterized, but did not find any in either or the closely related . Additionally, we performed RNA sequencing on testes obtained from adult males and did not identify potential PLCZ1 orthologs in our dataset or in previously collected ones. These findings suggest that PLCZ1 may have been lost in the lineage and raise the question of how fertilization triggers calcium release and egg activation in these species.