Fast and efficient molecule delivery into Euglena gracilis mediated by cell-penetrating peptide or dimethyl sulfoxide

This study describes the development of two methods for delivering exogenous materials into Euglena gracilis, a unicellular flagellate organism. We report that the use of Pep-1, a short cell-penetrating peptide (CPP), or dimethyl sulfoxide (DMSO) can mediate fast and efficient intracellular delivery of exogenous materials into E. gracilis, achieving cellular entry efficiency as high as 70-80%. However, compared with human cells, the penetration of this algal cell with CPP requires a much higher concentration of purified proteins. In addition, upon convenient treatment with DMSO, E. gracilis cells can efficiently adsorb exogenous proteins and DNA with 10% DMSO as the optimal concentration for Euglena cells. Our results provide more options for the E. gracilis transformation 'toolkit box' and will facilitate future molecular manipulations of this microalgal organism.