Developmental changes of Artemia ribonuclease.

Encysted gastrulae of Artemia contain a particulate ribonuclease functionally analogous to that present in larvae. This activity is 1/200 times lower than that found in developed larvae and remains constant during embryonic development. Concomitant with the hatching of the larvae, there is a burst in enzyme activity (25-30-fold) and a change in its cellular location from the particulate fraction to the cell cytosol. The larval enzyme increases as development progresses (10-fold) and appears as two distinct peaks of activity after gel filtration. The heavy peak greatly decreases with the time of development. The results are discussed in relation to the control of the expression of this enzyme.