Development of transgenic zooplankton Artemia as a bioreactor to produce exogenous protein

Although the crustacean Artemia has been commonly used as an experimental organism and served as a live bait feed for aquaculture, gene transfer system on Artemia sp. to generate stable lines is not well developed. In this study, we optimized a condition for cyst-eletroporation and generated stable lines of transgenic A. sinica. Two expression plasmids directed by the hybrid promoters of cytomegalovirus (CMV) and medaka β-actin (Mβ) were co-electroporated on decapsulated cysts: pCMV-Mβ-GFP contained GFP reporter gene and pCMV-Mβ-ypGH contained yellowfin porgy GH (ypGH) cDNA. We examined the GFP shown in the Artemia larvae and found that the expression rate was 13.3% (3,219 out of 24,054 examined). We then chose 200 G0 founders which strongly expressed GFP to generate transgenic lines. Homozygotic strains derived from F4 generation of each transgenic line, A3 and A8, were obtained. We proved that transgenic lines A3 and A8 also harbored pCMV-Mβ-ypGH and produced recombinant ypGH with a concentration of 0.089 and 0.032 μg per 50 homozygotic nauplii, respectively. Ten live Artemia nauplii were fed daily to zebrafish larvae during 25 to 35 days of post-fertilization. The average body length gain rates of zebrafish larvae fed transgenic Artemia were 16-20% greater than those of control group, indicating the exogenous ypGH produced by transgenic Artemia is functional. Therefore, we concluded that the transgenesis on Artemia is developed, and transgenic Artemia might be highly potentially useful as a new bioreactor material for application in aquaculture and biological researches.