Van Dyke – Applied animal physiology
We are broadly interested in how animals, including humans, “work”. Animals must balance demands of competing physiological functions to maintain homeostasis. An example we study is the placenta in live-bearing vertebrates. The placenta connects a mother to embryos that are not genetically identical to her (half of their genes are from their father), and there is a risk that her immune system might kill them. How placentas provide nutrition to embryos, despite this immune challenge, has major implications for understanding how reproduction, development, and immune function are regulated so that both mother and baby survive.
More broadly, all animals deal with similar immune and environmental challenges, and use many of the same molecular and physiological mechanisms to survive. Hence, animals are excellent models for discovering novel therapies for humans. We use a range of molecular and physiological techniques to study these mechanisms to improve human health and environmental outcomes.
Evolution and function of vertebrate placentas
The placenta is necessary for development in all eutherian mammals, including humans. It provides nutrition, oxygen, and water to developing offspring, and removes carbon dioxide and other wastes. It provides a mechanism through which the embryo and mother can communicate, via molecular signals, and protects the embryo from the mother’s own immune system. The complex dynamic between placental and immune function may even explain why men and women suffer different rates of autoimmune diseases and cancer.
Perhaps surprisingly, the placenta has independently evolved many times in animals that give birth to live young, including at least 5 times in lizards and many times in fish and sharks (compared to once in all mammals, including marsupials). The morphological structure and general function of the placenta are similar across all of these groups. Few organs have evolved repeatedly like the placenta, which makes the placenta uniquely suited for understanding how complex organs evolve.
We study this question at multiple scales. At the molecular scale, we compare how nutrient transport molecules like solute carriers (SLCs) have been selectively recruited at genomic and proteomic levels to transport nutrients to embryos in different species. At the whole-organism scale, we study how environmental conditions, like food abundance and immune challenges, interact with these molecular mechanisms to impact reproductive success. We also study how these interactions lead to evolutionary differences in placental function within widespread species.
Environmental impacts on reproduction, development, and immune function
Animals must successfully deal with a number of environmental challenges in order to survive and reproduce the next generation. Humans are no different, and our medical industry exists to help us meet these same kinds of challenges. In comparison to us, animals’ abilities to deal with environmental challenges without the medical industry is remarkable, and explains why many of our medical advancements come from novel molecular discoveries in animals. Animal venoms, hormones, and immune factors have all been developed into human medical therapies.
Our research aims to discover the novel mechanisms animals use to deal with environmental impacts on reproduction, development, and immune function. We are particularly interested in nutritional and pollution impacts. The nutrients animals eat provide both the energy and chemical building blocks animals need to produce new molecules, cells, and tissues. Pollutants, including heavy metals, interact with molecular processes and cause breakdowns in reproduction, development, and immunity.
Two examples of our research focus on freshwater turtles, which have remarkable immune systems. Adults use a powerful innate immune response to prevent systemic bacterial infections after injuries. Eggs resist fungal infections despite not having an immune system aside from the immune factors provided by their mother during egg production. We use molecular and physiological approaches to determine how these functions work, and how they are maintained despite food restrictions and pollution. We collaborate with A/Prof Ricky Spencer (Western Sydney University) to link this research to conservation of endangered turtles.