Release of hyaluronidase during in vitro development of Ascaris suum from the third to fourth larval stage

An enzyme that degraded glycosaminoglycan hyaluronic acid was released duri ng in vitro development of Ascaris suum L3 to L4. The enzyme did not hydrol yze glycosaminoglycan chondroitin sulfate A. One molecular form of hyaluron idase was detected, with a molecular weight estimated at 47.8 +/- 8.6 kDa b y sucrose density gradient centrifugation and at 55.0 +/- 1.3 kDa by substr ate SDS-PAGE zymography. Activity of the enzyme was optimal between pH 5.0 and 6.0, and was present at neutral pH. Hyaluronidase activity was not affe cted by 5 mM concentrations of cupric sulfate, zinc chloride, calcium chlor ide, manganese chloride or EDTA. In addition, NaCl had no effect on enzyme activity at concentrations of 0.2-1.0 M. The highest level of hyaluronidase was present in culture fluid collected between days 4 and 6 of in vitro cu lture, and this period corresponded with that of the highest rate of increa se in the percentage of L4. The presence or absence of hyaluronic acid play s a key role in basic developmental processes of vertebrates and is regulat ed, in part, by hyaluronidases. Developmental processes occurring during th e transition of A. suum L3 to L4 may likewise depend on hyaluronidase. In a ddition, the infection process of a number of organisms, including some nem atodes, depends on hyaluronidase. A. suum may likewise utilize hyaluronidas e to facilitate larval migration within the host.