To serve the metabolic needs of the developing embryo , Oviparous animals, such as decapod crustaceans and the prawn Macrobrachium rosenbergii in specific, are characterized by an elaborated vitel logenesis process . The process is designated by enhanced production and accumulation of v itellogenin (Vg), the major yolk protein component of the oocyte. Yolk accumulation is commenced by receptor-mediated endocytosis . The specific interaction between Vg and its receptor and the immense accumulation of the Vg in the oocyte during vitellogenesis is utilized herein to develop a sophisticated oocytes-specific delivery tool .
A specific peptide conserved among crustaceans vitellogenin was derived from M. rosenbergii Vg, synthesized, and labeled with a fluorescent fluorophore. The fluorophore-labeled Vg-peptide was found to enter into M. rosenbergii and Litopeneous vannamei oocytes both in vitro and in vivo . However, a peptide with the same amino acid composition but scrambled order (scVg ) could not enter the oocytes. Additionally, in vitro and in vivo experiments demonstrated that dsRNA electrostatically connected to the Vg-peptide is internalized into M. rosenbergii oocyte . PAX6 dsRNA connected to the Vg-peptide and injected into vitellogenic females was found functional and capable of inducing gene silencing, which led to the interruption of the eye development in the embryos of the treated mothers. More than 90% of the embryos of treated mothers were affected.
The high efficiency of the delivery tool and the fact that it is conserved throughout crustaceans would benefit the fast-growing crustacean aquaculture. Specifically, when a single treated female would produce thousands of affected embryos with the desired trait. The tool could be utilized for silencing aquaculture-relevant genes to develop a sustainable fast-growing and vaccinated population.