Doctoral defence: Ciara Baines “Adaptation to oncogenic pollution and natural cancer defences in the aquatic environment”

On 9 June at 10:15 Ciara Baines will defend her doctoral thesis “Adaptation to oncogenic pollution and natural cancer defences in the aquatic environment” for obtaining the degree of Doctor of Philosophy (in Zoology and Ecology).

Supervisors:
Associate Professor Tuul Sepp, University of Tartu
Associate Professor Lauri Saks, University of Tartu
Research Fellow Mathieu Giraudeau, La Rochelle University (France)

Opponent:
Professor Joachim Sturve, University of Gothenburg (Sweden)

Summary
All multicellular organisms can get cancer, but species differ in their ability to resist this disease. Since large body size and longer lifespan increase the likelyhood of cancer, larger and longer living species have evolved stronger cancer defence mechanisms to protect themselves. For example, when the risk of dying because of cancer is 17% in humans, it is less than 5% in elephants. The likelihood that an animal develops cancer does not only depend on their lifespan and body size, but also of their environment. Pollution has increased cancer risk in both humans and other animals. Animals that live in aquatic environment are especially vulnerable to oncogenic pollution, since pollution spreads quickly in the water and accumulates for long time in the sediments. In my PhD thesis, I studied the links between pollution and cancer in aquatic species. This link has been so far demonstrated in 30 aquatic animal species, with most studies on fish. I have also found that fish who live longer and grow larger have to compensate the number of copies of genes allowing them to grow large with additional copies of genes suppressing cancer. My comparative study allowes also to predict which fish species have the strongest and which have the weakest genetic defences against cancer. By studying two species living in the bottom of the sea, flounder and dab, I asked why one of them is more vulnerable to cancer than the other. I found that for cancer to occur in flounder, many genes need to be suppressed. The same is not seen in dabs. This suggests that flounders have defence mechanisms against cancer that are not present in dab. Currently, understanding natural cancer defence mechanisms has become crucial, as human induced environmental change has increased cancer prevalence in both humans and wild species. Understanding the differences between species in cancer defences can help to predict the effect of pollution on wild species, and contribute to the development of better regulatory mechanisms for protecting wild species.

The defence will be also held in Zoom: https://ut-ee.zoom.us/j/97192497358?pwd=WjRyQ1d5WnVGa3IxMUZqV21pUkRndz09 (Meeting ID: 971 9249 7358, Passcode: 434375).

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