Saliva of the soft tick, Ornithodoros moubata, contains anti-platelet and apyrase activities.
1. Pilocarpine-induced saliva of the soft tick Ornithodoros moubata inhibits platelet aggregation induced by ADP or collagen, even when diluted 2000 times into platelet rich plasma. 2. Saliva contains apyrase (ATP-diphosphohydrolase) activity, which has an optimal pH of 7.0 for ADP and of 8.0 for ATP hydrolysis, respectively. Both Ca2+ and Mg2+ activate the reactions. 3. The mean specific activities for ATP and ADP hydrolysis at pH 7.5 were 0.97 and 0.74 mumoles orthophosphate/min/mg protein. 4. These results, which demonstrate for the first time such activities in the saliva of soft ticks, support the hypothesis that the saliva of blood sucking arthropods serves an anti-hemostatic role during feeding and that large amounts of salivary apyrase activity have evolved independently in hematophagous arthropods.
Harvard School of Public Health, Department of Tropical Public Health, Boston, MA 02115.
J M
JM
Ribeiro
T M
TM
Endris
R
R
Endris
D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001081:Apyrase / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002413:Cations, Divalent; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D010975:Platelet Aggregation Inhibitors; D012463:Saliva / Q000378:metabolism*; D013045:Species Specificity; D013987:Ticks / Q000502:physiology*
D002413:Cations, Divalent; D010975:Platelet Aggregation Inhibitors; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D001081:Apyrase; D008274:Magnesium; D002118:Calcium