It has been long recognized that glycans play a wide spectrum of essential roles in metazoan organisms, while defects in glycosylation are involved in numerous human diseases and abnormalities, from cancer to brain malformation and defects of immune system. However, the complexity of glycosylation pathways and limitations of genetic and in vivo approaches available for studying glycosylation in higher animals significantly impede the research in mammals. We are using the advantages of Drosophila model system, including its decreased genetic redundancy, powerful arsenal of molecular genetic approaches, and comprehensively characterized development, to elucidate mechanisms underlying the function of glycosylation in development and physiology. We employ a multidisciplinary approach to study the roles of several novel glycosyltransferase genes at molecular, cellular, and organismal levels. Currently, our laboratory is involved in two main projects: one project focuses on studying the function of sialylation in the central nervous system, while another project is aimed at elucidation of molecular mechanisms of protein O-mannosylation.