Biochemical Studies on Tick Embryogenesis: Lipovitellin and Protease Activity in Dermacentor Andersoni (Acari: Ixodidae)12

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Abstract
Changes in concentrations of 3 hemoprotein fractions (lipovitellins A and B and a minor hemoprotein C) separated from egg homogenates of the ixodid tick Dermacentor andersoni by ion exchange chromatography were determined during embryogenesis and in the unfed larva. The acid and neutral protease activity levels were measured in the egg homogenates. Lipovitellin A disappeared between days 4 and 8 of embryogenesis; lipovitellin B, the major hemoprotein, decreased in newly hatched and unfed 15-day-old larvae. The fraction C level remained almost constant throughout embryogenesis (16–18 days) and in newly hatched and unfed 15-day-old larvae. Acid and neutral protease activities both reached maximum levels on day 4 (when lipovitellin A was reduced) and on days 8 and 10 of embryogenesis. These data suggest that specific proteases are involved in digesting egg lipovitellins (hemolipoglycoproteins) and converting them into components for nourishing the developing embryo and the unfed larva.