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.

Evaluation of qPCR reference genes in GH-overexpressing transgenic zebrafish (Danio rerio).

Reference genes (RGs) must have a stable expression in tissues in all experimental conditions to normalize real-time quantitative reverse transcription PCR (qRT-PCR) data. F0104 is a highly studied lineage of zebrafish developed to overexpress the growth hormone (GH). It is assumed that the transgenic process may influence the expression levels of commonly used RGs. The objective of the present study was to make a comprehensive analysis of stability of canditade RGs actb1, actb2, b2m, eif2s2, eef1a1, gapdh, rplp2, rpl7, rpl13α, tuba1, and rps18, in gh-transgenic and non-transgenic zebrafish. Liver, brain, intestine and muscle samples from both groups had qRT-PCR results analyzed by dCt, geNorm, NormFinder, BestKeeper, and RefFinder softwares. Consensus analyses among software concluded that rpl13α, rpl7, and eef1a1 are the most stable genes for zebrafish, considering the studied groups and tissues. Gapdh, rps18, and tuba1 suffered variations in stability among different tissues of both groups, and so, they were listed as the genes with lowest stability. Results from an average pairwise variations test indicated that the use of two RGs would generate reliable results for gene expression analysis in the studied tissues. We conclude that genes that are commonly used in mammals for qRT-PCR assays have low stability in both non-transgenic and gh-transgenic zebrafish reinforcing the importance of using species-specific RGs.