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, A rtemia franciscana embryos were bombarded with high velocity gold micr oparticles coated with a circular plasmid containing a luciferase repo rter gene placed under the control of the Drosophila melanogaster hsp 70 promoter (3000 to 10000 embryos per shot). Even for the most drasti c ballistic parameters investigated on dechorionated cysts (rupture di sk, 1800 psi; distance D between the stopping screen and the embryos, 35 mm), no significant luciferase activity was detected after heat sho ck (30 min, 41 degrees C). After bombarding protruding embryos obtaine d 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 lucifer ase activity was observed 12 and 24 h after bombardment, but not at 48 h. In this particular model, the data suggest transient luciferase ex pression, with a peak of luciferase activity within the 12 h following bombardment. These results indicate that the ballistic technique is u seful for studying transgene promoter efficiency in crustaceans and su ggest its utility for attempting the production of transgenic animals.