DEVELOPMENTAL PATTERN OF PLASMINOGEN-ACTIVATOR ACTIVITY IN CHICK BRAIN HEMISPHERES

Plasminogen activators play key roles in several developmental events. Ln previous works we demonstrated the existence of typical developmen tal patterns of protease activity in the chick optic lobe and cerebell um. The aim of this work is to study the temporal pattern of developme nt of plasminogen activator activity in the brain hemispheres. Plasmin ogen activator activity was assayed in soluble fractions derived by ul tracentrifugation from Triton X-100 treated membrane fractions by usin g a radial fibrinolytic assay. Employing different inhibitors and anti -plasminogen activators antibodies we showed that developing brain hem ispheres express only one type of enzyme which corresponds to the urok inase-type. Other results indicate that the protease activity displays a temporal pattern which completely differs from those of general par ameters of development. This suggests that the plasminogen activator a ctivity is developmentally regulated and could display specific functi ons during particular stages of development.