Performing functional studies of Xenopus laevis intermediate filament proteins through injection of macromolecules into early embryos

The small size of Xenopus laevis embryos and their external development make it easy to study early developmental stages in their systems. This chapter discusses Xenopus laevis as a vertebrate model for studying intermediate filament (IF) involvement in development, and provides procedures for obtaining, dejellying, and injecting embryos. The injection of macromolecules into Xenopus embryos has proven to be an effective method of manipulating IFs to study their function during vertebrate development. Although, IFs are generally dispensable for vertebrate development to proceed, they nonetheless enhance many of its essential processes such as gastrulation, muscle organization, and axonal outgrowth. Although IFs may not be essential for the survival of individual cells, they are arguably indispensable for the survival of the species. It is now also relatively straightforward to create transgenic Xenopus embryos by fertilizing oocytes with sperm nuclei that have been incubated with transgenes. By using Xenopus appropriately with other model systems, it is yet to explore the way this complex family of genes, with its exquisitely regulated patterns of expression, contributes to the cell and to the organism. Thus, Xenopus is likely to remain an important model system for IF studies for some time to come.