Zinc Acquisition and Handling in the Pacific Hagfish (Eptatretus stoutii)

  • Author / Creator
    Wall, Carley Jeanne
  • Acting as a co-factor for hundreds of enzymes, zinc (Zn) is an essential trace metal required for organismal success across all phyla. When aquatic organisms such as fish are Zn deficient, growth, metabolism, and health are all negatively impacted. However, Zn in excess may also impair overall piscine survival. The early diverging Pacific hagfish (Eptatretus stoutii) was used as a research organism in this thesis.
    Similar to other fish, hagfish may acquire environmental nutrients across their hindgut and gills. However, they have also demonstrated a capacity for nutrient uptake across their skin. I investigated where hagfish accumulate Zn, how they acquire Zn2+ across epithelia, and what potential cellular mechanisms may be present.
    Hagfish exposed to 2 µM and 100 µM Zn for 6, 24, and 48 hours demonstrated significant Zn accumulation in the gills, as well as within the blood plasma and the foregut. In a separate experiment, uptake kinetics for the hindgut, gill, and skin were biphasic. At higher concentrations of Zn, uptake was dominated by diffusive pathways, whereas saturable, sigmoidal uptake was observed at lower Zn concentrations. Measured affinity constants revealed the hindgut to have the lowest affinity for Zn, with the highest affinity occurring in the gill.
    The sigmoidal nature of the uptake curves led me to test Zn2+ uptake in the presence of putative metal competitors in an attempt to elucidate which protein transporters are used for Zn2+ transport in the hagfish. Within the hindgut and skin, no significant effect on Zn2+ uptake occurred when metals were in concentrations 2X and 5X that of Zn. Zn2+ uptake significantly increased within the gill in the presence of lanthanum, a known calcium channel inhibitor.
    Metallothionein (MT) levels within hagfish exposed to 38 µM Zn for a period of 0, 1, 3, 5, and 7 days were quantified, with the liver and intestine having the highest concentrations of MT, however, an induction of MT production was not demonstrated.

  • Subjects / Keywords
  • Graduation date
    Fall 2019
  • Type of Item
  • Degree
    Master of Science
  • DOI
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