Regulation of trance metal uptake and metabolism in freshwater fish

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The long-term objective of my research program is to study the molecular and physiological processes that govern essential and non-essential trace metal uptake and handling in freshwater animals, particularly fish. Over the next five years, I have proposed to study the three following topics. (1) Iron is an essential metal that is critical for all vertebrates including fish, and both iron deficiency and abundance in the body can cause adverse effects. However, very little is known about the mechanisms by which fish regulate iron uptake and metabolism. Fish are unique among the vertebrates, since they can absorb metals both via the gill and gut. I will examine the responses of key molecular and physiological processes involved in iron uptake and metabolism in fish during iron deficiency and overload. This is expected to enhance our understanding of how fish regulate their physiology to cope with the variable iron status in the environment. (2) Cadmium is a non-essential metal, which is very toxic to organisms. It is a ubiquitous aquatic contaminant, and recent evidence demonstrates that fish accumulate cadmium through calcium and iron uptake pathways both from water and diet. Hence, cadmium may cause toxicity by influencing the calcium and/or iron balance in fish. I will investigate how calcium and iron status in the water and diet affect cadmium uptake and metabolism in fish. This study could help in identifying sensitive physiological endpoints for assessing cadmium exposure and/or effects in fish living in metal-contaminated aquatic environments. (3) Iron nanoparticles are increasingly being used for environmental remediation, with the potential risk of adverse consequences to aquatic life. I will investigate how waterborne iron nanoparticle exposure affects physiological functions in fish. At present, there is a great paucity of knowledge on the impacts of nano-iron contamination in aquatic ecosystems, and my research is expected to provide important information in this regard.