raffinose and turanose

A behavioural study on the ant Lasius niger was performed by observing its feeding responses to 85 compounds presented in a two-choice situation (tested compound versus water control or sucrose solution). Among these compounds, only 21 were phagostimulating: six monosaccharides (D-glucose, 6-deoxy-D-glucose, L-galactose, L-fucose, D-fructose, L-sorbose), four derivatives of D-glucose (methyl alpha-D-glucoside, D-gluconolactone and 6-chloro- and 6-fluoro-deoxy-D-glucose), five disaccharides (sucrose, maltose, palatinose, turanose and isomaltose), one polyol glycoside (maltitol), three trisaccharides (melezitose, raffinose and maltotriose) and two polyols (sorbitol and L-iditol). None of the 16 non-carbohydrate non-polyol compounds tested, although perceived as sweet in humans, was found to be active in ants. The molar order of effectiveness of the major naturally occuring compounds (melezitose > sucrose = raffinose > D-glucose > D-fructose = maltose = sorbitol) is basically different from the molar order of their sweetness potency in humans (sucrose > D-fructose > melezitose > maltose > D-glucose = raffinose = sorbitol). On a molar basis melezitose is in L. niger about twice as effective as sucrose or raffinose, while D-glucose and D-fructose are three and four times less effective, respectively, than sucrose or raffinose. From a structure-activity relationship study it was inferred that the active monosaccharides and polyols should interact with the ant receptor through only one type of receptor, through the same binding pocket and the same binding residues, via a six-point interaction. The high effectiveness of melezitose in L. niger mirrors the feeding habits of these ants, which attend homopterans and are heavy feeders on their honeydew, which is very rich in this carbohydrate.

Topics: Animals; Ants; Deoxyglucose; Disaccharides; Fructose; Fucose; Galactose; Glucose; Humans; Isomaltose; Maltose; Models, Chemical; Raffinose; Sorbitol; Sorbose; Structure-Activity Relationship; Sugar Alcohols; Taste; Trisaccharides

We have previously described the presence of haemagglutinins in tissues of the tick, Rhipicephalus appendiculatus and determined their sugar specificities by inhibition experiments. In this study, haemagglutination inhibitory sugars are shown to have an effect in vivo on the abundance of Theileria parva infected salivary gland acini in Rhipicephalus appendiculatus. A significant increase (P < 0.05) was observed in T. parva acinar infection rates in the salivary glands of R. appendiculatus fed on ears of rabbits infused with melibiose and raffinose. In contrast, mannose and turanose (non-haemagglutination inhibitory sugars) did not cause elevation of T. parva acinar infection rates. The effect of melibiose in elevating acinar infections was observed when used only during T. parva maturation in the salivary glands but not during parasite pick-up from an infected bovine host. Stabilates produced from ticks with elevated acinar infections did not differ from control stabilates in infectivity to cattle, by comparison of prepatent periods to pyrexia, or parasitosis, or in the severity of reactions.

Topics: Animals; Carbohydrates; Cattle; Disaccharides; Female; Hemagglutination; Male; Mannose; Melibiose; Rabbits; Raffinose; Salivary Glands; Theileria parva; Theileriasis; Ticks