Vaccination Against Sexual Maturation in Farmed Cod10 July 2013
NORWAY - Early onset of sexual maturity is a great problem in cod aquaculture because of negative effects on growth, feed conversion and health.
Farmed cod that escape can also affect the genes of wild fish. Research fellow Adrijana Skugor of the food research institute Nofima has examined biological mechanisms that control the development of the sex organs in cod for her doctorate.
She has studied both individual genes and the whole cod genome to obtain more information about how the germ cells of the embryo develop into eggs and sperm.
A "dead end" shows the way
Ms Skugor has previously studied zebrafish and has made use of the knowledge she gained then. In zebrafish, the dead end gene (DnD) is necessary for sexual maturity, and Adrijana has now been studying the significance of this gene in Atlantic cod.
She injected cod embryos with a molecule that blocks DnD and found that inactivation of the gene affected the development of germ cells also in cod. In addition, Adrijana used micro array screening to study the effects of DnD inactivation in a wider context.
Transferring knowledge to salmon research
"We now know that DnD is a good candidate for preventing the onset of sexual maturity, so that fish become sterile," said Ms Skugor. "But the method used is costly and complicated and cannot be used commercially. It has however been important in the work of developing tools that make it easier to obtain information about how cells develop."
As a commercial method, it may be better to block the dead end proteins in the mother fish, rather than blocking the dead end gene in the embryo. As post doc fellow Adrijana will establish this strategy in salmon, because early sexual maturation is a problem also in salmon farming. In this way, much of what has been learned from studying cod can be brought into the work on salmon, in the same way as Adrijana previously made use of knowledge from zebrafish studies.
"Adrijana's research has improved our knowledge about the differentiation of germ cells and about the embryonic development of Atlantic cod", said supervisor Øivind Andersen, Senior Scientist at Nofima.
Ms Skugor's disputation was on 17 June at UMB’s Dept. of Animal and Aquacultural Sciences (IHA). Her main supervisor has been Øivind Andersen, Senior Scientist at Nofima and Professor at IHA.
The English title of the thesis is Transcriptional profiling of maternally deposited factors in Atlantic cod (Gadus morhua) embryos and the role of Dead end in primordial germ cell development.
Ms Skugor was educated at UMB (the Norwegian University of Life Sciences) and took her master degree at Nofima. The PhD fellowship has been funded by the Research Council of Norway.
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