Glycosylation mutants of animal cells have proved invaluable in delineating the pathways of cellular glycosylation mechanisms and in studying the biological consequences of specific changes in carbohydrate structure at the cell surface. This laboratory has previously isolated and partially-characterized eleven different glycosylation mutants from Chinese hamster ovary (CHO) cells. These mutants were selected for resistance to the toxicity of plant lectins. They have been classified into eight recessive complementation groups and one dominant class. Recent experiments from our laboratory suggest that many more mutants analagous to those previously described remain to be uncovered. The major aim of this application is to use specific selection protocols designed to obtain the entire repertoire of lectin-resistant glycosylation mutants of CHO cells. Sequential lectin selections have been devised which should eliminate known Lectin resistant mutants and thereby select for new Lectin resistant phenotypes. Lectins other than those previously used will also be examined as selective agents. Lectins which interact with terminal sugar residues of carbohydrate chains are of particular interest since they might be expected to give rise to mutants expressing subtle structural alterations in surface carbohydrate. New isolates will be characterized genetically (by complementation analysis) and biochemically to determine whether the new phenotype arises from altered glycosylation of membrane glycoproteins, glycolipids and/or proteglycans. Studies will be initiated to determine whether any of the glycosylation mutants isolated exhibit an altered ability to induce tumours in and to invade the tissues of nude mice. Such studies are aimed at determining whether surface carbohydrate plays a role in one or more of the many steps involved in the complex metastatic process.