TRANSIENT EXPRESSION OF A LUCIFERASE REPORTER GENE AFTER BALLISTIC INTRODUCTION INTO ARTEMIA-FRANCISCANA (CRUSTACEA) EMBRYOS

Using the PDS 1000/He ballistic gene transfer apparatus from BioRad, Artemia franciscana embryos were bombarded with high velocity gold microparticles coated with a circular plasmid containing a luciferase reporter gene placed under the control of the Drosophila melanogaster hsp 70 promoter (3000 to 10000 embryos per shot). Even for the most drastic ballistic parameters investigated on dechorionated cysts (rupture disk, 1800 psi; distance D between the stopping screen and the embryos, 35 mm), no significant luciferase activity was detected after heat shock (30 min, 41 degrees C). After bombarding protruding embryos obtained 20 h after dechorionated cyst rehydration, the best result in terms of embryo survival and luciferase activity was obtained for D = 35 mm with a 450-psi rupture disk. For these parameters, significant luciferase activity was observed 12 and 24 h after bombardment, but not at 48 h. In this particular model, the data suggest transient luciferase expression, with a peak of luciferase activity within the 12 h following bombardment. These results indicate that the ballistic technique is useful for studying transgene promoter efficiency in crustaceans and suggest its utility for attempting the production of transgenic animals.