Eggs and sperm are made by special cells called germ cells. Germ cells are critical not only to organismal survival but also to species survival and evolution, because they are the only cell type capable of producing the next generation. It is therefore critical to understand the genetic and molecular mechanisms that make sure germ cells are specified in embryos. Studies using traditional model organisms such as mice and fruit flies have suggested that some animals use an 'inheritance' mechanism to specify germ cells, whereby germ cell-determining substances are placed into developing eggs before embryonic development begins. In other animals, an 'inductive' mechanism operates, whereby cells exchange signals to determine which cells should become germ cells. For decades it was thought that most animals used the inheritance mechanism, and that mammals were exceptional in using the inductive mechanism. Prior research by the PI challenged this assumption by discovering the first example of a non-mammalian animal that uses the inheritance mechanism. To make this discovery, they studied germ cells in a cricket called Gryllus bimaculatus. The current project will extend this novel finding by determining whether the signals used to specify germ cells are actually the same in both mammals and crickets. If this proves to be the case, it could mean that the same signaling mechanism was used to specify germ cells in a last common ancestor of all animals. This work has high transformative potential, as it will have a radical impact on our understanding of how germ cells are specified in diverse animals, and how the mechanisms used to specify germ cells evolved. The current project will also develop new educational tools that use science fiction films to engage both the general public and university undergraduates in the study of developmental biology and genetics.
