The identification of the stumpf (stp) mutation in zebrafish as the mutationof UDP-N-Acetylglucosamin-
phosphate-transferase, will give the possibility to perform in vivo studies of the first step of N-glycosylation
pathway in a whole animal model. Up to now only in vitro assays with cell cultures or extracts were available.
Glycosylated proteins are used in eukaryotic cells for many purposes, like providing structural integrity and
creating cell identity. proper glycosylation is needed for correct folding and functioning of proteins like Rhodopsin
and is also involved in more complex events like neovascularization and angiogenesis. Zebrafish as a model
organism is used in various functional studies. The GPT is specifically inhibited by the antibiotic tunicamycin
(TU). This project will study the effect of mutated GPT (and/or application of TU) on cellular structures of
cartilage, eye and vascular system of wild type, stp-heterozygote and stp-homozygote embryos by using electron
microscopy and whole mount staining methods. Injection experiments will show effects of overexpression of
functional, wild type GPT in stp mutants and mutant GPT in wild type embryos. Both the development of wild
type and of stp mutant vascular system will be monitored. This work will further elucidate the effects of GPT on
cellular and vascular structures and could help to understand the role of protein glycosylation and GPT in tumor
neo-vascularization.