Expression patterns of Ubiquitin and ubiquitin-conjugated proteins in the early development of Xenopus laevis

By RT-PCR analysis, we confirmed that Xenopus ubiquitin (Xub) is constitutively expressed at a high basal level during all stages of embryogenesis, In situ hybridization was performed to study in more detail the spatial expression pattern on Xub. The first attractable signals were observed in the neural fold and in the anteriormost region of early neurula. At the tailbud stage, the signals concentrated in cells of the developing brain, otic vesicle, branchial arches, pronephros and somites, As development progressed Xub transcript gradually localized to abdominal region. We also have examined immunohistochemically the distribution of ubiquitin-conjugated proteins using a monoclonal antibody raised against polyubiquitin of Amoeba proteus, The immunostaining patterns coincided largely with the expression patterns of Xub, Furthermore, we compared the expression patterns of Xub with TUNEL staining to identify a relationship between ubiquitin and programmed cell death during the development of Xenopus.