Enzyme activity of the cytochrome system of the egg and larva of the cattle tick (boophilus microplus)

Abstract

The enzymatic activities of the succinate-ytochrome c reductase system, the NADH--cytochrome c reductase system, the NADH oxidase system, and cytochrome c oxidase were determined spectrophotometrically in particulate preparations of eggs and larvae of B. micro plus. All enzyme systems were detectable in the eggs of the tick and the activities remained relatively constant. At day 0, the day of hatching, an 80% increase inNADHcytochrome c reductase was recorded. No other appreciable change occurred until about day 5 when there was a sharp increase in cytochrome c oxidase activity. This was followed by an increase in succinate-hytochrome c reductase on day 7. NADH oxidase did not increase until about day 9. The reductases accounted for about 70% of the total oxidoreductase activity during the early larval phase but from day 9 the reductases declined, concomitant with an increase in oxidase activity. The oxidases reached a maximum of 66% of the total oxidoreductase activity about day 36. These changes in the cytochrome system are indicative of the increasing metabolic activity of the larvae with age. The increased respiratory activity also reflects the increasing demand for energy at a time when the larvae are seeking a host. Preliminary studies of the respiratory system in day 8 larvae of four strains (Yeerongpilly, Biarra, Ridgelands, and Mackay) of varying acaricide susceptibilities indicated some interstrain difference. The Mackay strain exhibited enzyme activities 2.5-3 times greater than the Biarra strain. © 1973 CSIRO.