SURFACE PROPERTIES OF BLOOD-STREAM TRYPANOSOMES (TRYPANOSOMA-BRUCEI BRUCEI)

Abstract

The African trypanosome (T. brucei brucei) in its bloodstream phase possessed rather unique surface properties. Results of lectin and Fe colloid binding studies indicated that the parasite''s surface coat is devoid of many types of exposed carbohydrate residues commonly expressed on a variety of mammalian cell types. These include: glucose, mannose, galactose, n-acetylglucosamine, n-acetylgalactosamine and neuraminic acid. A number of these carbohydrates (e.g., glucose, mannose, galactose and n-acetylgalactosamine) are buried within the surface coat as evidenced by lectin binding to trypsinized parasites. The surface of well preserved parasites lack exposed sialic acid and phospholipid moieties. Moribund parasites (or trypsinized organisms) with altered surface coats possess well defined phospholipid regions, but not negatively charged sialyl residues. Carbohydrates and phospholipids are not present in the outermost portion of the glycocalyx, exerting little or no influence on surface-mediated biological activities. The presence of such components on the plasmalemma is presumed to be structurally significant; especially during those developmental phases where the glycocalyx is absent, i.e., fly midgut phase.