Speaker
Description
In order to achieve electrical sex reversal technique of tilapia’s egg (O.niloticus) with androgen hormone delivery, the induced transmembrane potential (TMP) for electropermeabilization of the egg’s membrane is the first priority to evaluate through theoretical analysis. Previously, the closest available model to calculate TMP of tilapia’s egg was a shelled symmetrical prolate-spheroid. However, such model gave the large error to calculate the volume and surface of the egg then was improved to complete with our novel model as “hen-egg model” to analyze the implicit value of TMP. In practical, the values of TMP of the model has to be determined through experiments to confirm that there has no any impact on hatching and survival rates after electrical inductions with high-intensity electric fields. In principle, membrane thicknesses in real biological systems are very uniform because they are made up of lipid bilayers. This affects TMP directly and nonuniform thickness of the membrane leads to anomaly of its electrical capacitance, the thicker membrane at the equatorial plane than the two poles of the tilapia egg results in decreasing the membrane capacitance. For this case, our model revealed that the value of TMP depends on dielectric properties of the shell, directly correlated with the external electric field strengths and inversely affected by the depolarization factor. The latter term varied with the egg geometry depending on the values of semi-axes which depends on egg geometry. Both the characteristic capacitance and conductivity of each compartment of the egg are the main factors which determine TMP with the non-linear relation. However, variations of TMP depend on the given position of the egg surface dealing with the local position where the external field could induce a large value of TMP at the polar pore of the egg. At the polar, TMP has the maximum. This case is only applicable to the spheroid oriented in the field direction with one of its principal axes (the longest semi-major axis). When TMP reaches the critical value it causes electroporation. Experimental results showed that tilapia’s eggs suspended in EPM with the induced voltages ranged of 300-330-350-380-400-450 VDC had hatching rates of 92.00%±2.15%, 90.43%±3.11%, 94.73%±4.08%, 96.73%±3.25%, 60.58%±5.11%, and 68.16%±3.22% (±SD), respectively. Increasing the induced voltages affected survival rated as 89.33%±3.06%, 87.20%±7.00%, 88.52%±4.35%, 92.52%±4.35%, 68.20%±7.00% and 63.33%±3.06%, respectively. The critical limit of the induced voltages was at 350-380 VDC (threshold) which was the maximum value used to prevent cell damage with 5 square wave pulses, 50 µs pulse durations and 1:1 mark-space ratio.
