Arne Christensen

Associate Professor of Biology

Joined Westfield State University in 2019

Research Foci:

Fish osmoregulatory physiology: Fish in freshwater or seawater face different physiological challenges. In freshwater, diffusive ion loss and water gain must be counteracted by active ion uptake and retention, and dilute urine production. Conversely, in seawater, diffusive ion gain and water loss must be countered by active ion extrusion and increased water consumption. For fishes that remain in freshwater or seawater, the mechanisms that maintain ion homeostasis may be relatively static. On the other hand, fish which can adapt to freshwater and seawater, termed euryhaline, must do so by regulating the expression of proteins important for ion-transport and trans-epithelial resistance in tissues that are critical for maintaining ion-homeostasis, such as the gill. Gill ionocytes are a class of highly specialized cells that mediate ion transport between a fish and the aqueous environment. We are interested in how the morphology, and protein expression profiles, of these cells are related to the ability of euryhaline fish to move between freshwater and seawater environments.

Cytoskeleton: Cell morphology and function is dependent on the cytoskeleton, a network of protein filaments that are composed of actin (filamentous actin), tubulin (microtubules), or intermediate filaments. We recently described a unique arrangement of filamentous actin structures (white and red, image below) in the carapace integument of a small freshwater crustacean, Daphnia magna. Our current work aims to shed light on the form and function of these filamentous actin structures. What we learn about these structures in Daphnia stands to contribute to a broader understanding of actin dynamics, as actin is one of the most highly-conserved eukaryotic proteins. 

• B.S., University of Massachusetts Amherst
• Ph.D., University of Massachusetts Amherst
• Postdoctoral Appt., Conte Anadromous Fish Research Center