Delivery of 17 -Methyltestosterone through Tilapia Embryos by Electrical Pulse Inductions for Commercial Sex Reversal

The present study proposes an alternative technique of electrical sex reversal to enhance all-male sex reversal (MSR) of Nile tilapia using transient square pulse-electric fields for commercial benefits focusing on the study of mechanisms of electro-permibilization of 17 -Methyltestosterone (MT) androgen hormones through induced membrane of tilapia’s embryo ( Oreochromis niloticus L., Chitralada), during segmentation-pharyngula (2-3 days post fertilization). The technique were carried out for large-scale inductions of embryos suspensions with MT concentrations of 1,000 – 100,000 µg l -1 using square-pulse electric fields of amplitudes 100-500 volts (electric field intensities of 25-125 kV m -1 ), 100 µs pulse-period (50:50 mark space ratio) and 3 square pulses, respectively. It was found that the most suitable conditions of 350 V with MT concentration of 5,000 µg l -1 gave the maximum rate of male-sex reversal rate (MSR) of 89.42%±2.28%, hatching rate (HR) of 93.33%±0.58% and survival rate (SR) of 87.49%±1.71%, respectively. The off-spring rate (OSR) of male and female in the control group were 59.71%±3.00% and 46.33%%±1.53%, respectively, with hatching rate (HR) of 91.33%±1.53% and survival rate (SR) of 85.08% ± 4.16% (increasing MSR of 29.71%). Verifications of MT delivery were carried out through LC-MS/MS technique and RNA expression profiles by extraction of total RNA from induced MT embryos. Genes of male-sex development (up-regulated genes) of amh , ar , dmrt 1 , bmp 15 , gfd 9 and down-regulated genes of gsdf (where house keeping genes of rpl 13 a ) were investigated by Quantitative real-time PCR. The induced MT embryos with transient square pulse-electric fields showed expression of male-sex development genes. Keywords : tilapia; sex reversal rate; pulse electric fields; 17 -Methyltestosterone; gene