Administration of bioactive compounds to fish broodstock in captivity usually involves handling that results in undue stress. This is particularly true in late maturing species, which are considerable in size at sexual maturity. We are therefore exploring non-invasive methods of delivery to address this issue. For this talk, I will present our on-going work on the recombinant Southern Bluefin tuna luteinizing hormone (tuna LH), which we aim to deliver through the diet. LH regulates the final stages of maturation as well as the release of eggs in fish. These reproductive events are compromised in tuna broodstock held in captivity. Using molecular methods, we designed and created a recombinant DNA construct that encodes for the tuna LH. The construct can be converted into the functional hormone once introduced in live fish. We are collaborating with the laboratory of Prof Ming-Wei Lu, from National Taiwan Ocean University, who developed the technology to package DNA constructs in liposomes, which have been shown to protect DNA from stomach acids as well as facilitate the entry of DNA through the intestinal wall. We are currently evaluating the biological activity of the introduced recombinant tuna LH in tilapia, which belongs to the same phylogenetic order as tuna. As one of the indicators of the effect of the recombinant tuna LH, we are determining the expression level of the aromatase gene, which is one of the genes in the gonad that is directly regulated by LH. Preliminary results have shown an increase of aromatase expression in treated fish. In the long term, we aim to test the system in Southern Bluefin tuna broodstock.
2015 University Research Conference: Integrate, Innovate, Inspire, Sunshine Coast, Australia 13-16 July 2015