Carbohydrate-binding specificities and physico-chemical properties of lectins in various tissue of phlebotominae sandflies
Abstract
Physico-chemical properties and carbohydrate-binding specificity of hemagglutination activity (HA) were compared in tissue lysates and haemolymph of unfed and bloodfed females of five sandfly species. Sandfly gut lectins were found to be heat-labile, sensitive to dithiotreitol treatment, freezing/thawing procedures and were affected by divalent cations.
The pH optimum of HA ranged between 7.0-7.5. Specificity of gut HA of all species studied was directed towards aminosugars and some glycoconjugates, mainly lipopolysaccharide from Escherichia coli K-235, heparin and fetuin.
Gut HA of Phlebotomus papatasi (Scopoli, 1786) was strongly inhibited by lipophosphoglycan (LPG) from Leishmania major promastigotes. In females, that took blood, the HA was higher but the carbohydrate-binding specificity remained the same; this suggests that the same lectin molecule was present, at different levels, both in unfed and fed flies.
High HA was found in ovaries of fed females of Lutzomyia longipalpis (Lutz et Nieva, 1912), P. papatasi and P. duboscqi Neveu-Lemaire, 1906. In P. papatasi and P. duboscqi the HA was present also in the haemolymph and head lysates of both fed and unfed females.
Carbohydrate-binding specificity of HA present in these tissues was similar with the gut lectin.