Efficiency and cell viability implications using tip type electroporation in zebrafish sperm cells.

Sperm-mediated gene transfer (SMGT) has a potential use for zebrafish transgenesis. However, transfection into fish sperm cells still needs to be improved. The objective was to demonstrate the feasibility of tip type electroporation in zebrafish sperm, showing a protocol that provide high transfection efficiency, with minimal side-effects. Sperm was transfected with a Cy3-labelled DNA using tip type electroporation with voltages ranging from 500 to 1500 V. Sperm kinetics parameters were assessed using Computer Assisted Semen Analysis (CASA) and cell integrity, reactive oxygen species (ROS), mitochondrial functionality and transfection rate were evaluated by flow cytometry. The transfection rates were positively affected by tip type electroporation, reaching 64.9% ± 3.6 in the lowest voltage used (500 V) and 86.6% ± 1.9 in the highest (1500 V). The percentage of overall motile sperm in the electrotransfected samples was found to decrease with increasing field strength (P < 0.05). Increase in the sperm damaged plasma membrane was observed with increasing field strength (P < 0.05). ROS and sperm mitochondrial functionality did not present a negative response after the electroporation (P > 0.05). Overall results indicate that tip type electroporation enhances the internalization of exogenous DNA into zebrafish sperm cells with minimal harmful effects to sperm cells.