Transport Mechanisms for Zinc Across Gill and Intestinal Epithelia of Fish

EPA Grant Number: R826104
Title: Transport Mechanisms for Zinc Across Gill and Intestinal Epithelia of Fish
Investigators: Hogstrand, Christer
Institution: Kings College
Current Institution: Kings College , University of Kentucky
EPA Project Officer: Hahn, Intaek
Project Period: November 15, 1997 through November 14, 2000
Project Amount: $373,342
RFA: Exploratory Research - Environmental Biology (1997) RFA Text |  Recipients Lists
Research Category: Biology/Life Sciences , Ecosystems


To protect natural waters in a meaningful way there is a need to develop methods by which we can predict the effects of a toxicant in each particular environment. Such methods must be based on an understanding of how toxicants interact with organisms and the physical environment. Unfortunately, there are still large gaps in our knowledge in these areas. For example, uptake mechanisms for toxic metals by animals are largely unresolved. The main objectives of the proposed research are to delineate the molecular pathways for Zn uptake in freshwater acclimated rainbow trout and to characterize how Zn uptake is controlled. We hypothesize that there are regulated uptake pathways for Zn in fish that play important roles in toxicity and acclimation processes. Zn has been chosen as the focal substance of the project because our present knowledge about Zn uptake is farther advanced than that of most other toxic metals. Furthermore, present data suggest that Zn is a useful model substance for the more toxic metal, cadmium.


The proposed work falls into four sections: 1) Transfer of Zn across the basolateral membrane of the gill epithelium; 2) Analysis of the mechanisms regulating the apical entry of Zn in the gill epithelial cells; 3) Endocrine regulation of Zn homeostasis; and 4) Physiological characterization of intestinal Zn uptake. The studies involve detailed investigations of Zn transport across the apical and basolateral membranes of the gill epithelium including detection and characterization of Zn-transport proteins. Fish are sometimes able to acclimate to elevated concentrations of waterborne Zn and in rainbow trout this acclimation is based on an ability to reduce Zn uptake across the gills. A combination of standard cell biology and whole animal approaches will be used to elucidate the intracellular and endocrine signaling systems that may be involved in control of Zn uptake and, thus, acclimation to waterborne Zn. While uptake of Zn across the gill epithelium is of primary concern for acute Zn toxicity, intestinal Zn uptake is likely more important for the whole body Zn accumulation. Movement of Zn and other metals across the intestinal epithelium has historically been difficult to study. Thus, in one of the four sections of this project, we will take advantage of a newly developed in situ technique and produce new data on intestinal Zn uptake in freshwater fish. This preparation will allow studies on the possible modulating effects of inorganic ions, amino acids, and peptides on Zn uptake.

Expected Results:

The proposed research should greatly advance our knowledge of Zn uptake mechanisms and their homeostatic control in fish. The generated information should help us to predict toxic effects of Zn in different freshwater environments and explain why fish sometimes are able to acclimate to Zn and sometimes not.

Publications and Presentations:

Publications have been submitted on this project: View all 27 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 7 journal articles for this project

Supplemental Keywords:

water, freshwater, hardness, bioavailability, metabolism, animal, fish, organism, cellular, enzymes, heavy metals, zinc, calcium, environmental biology, cell biology, integrative biology, environmental physiology, zoology, uptake, regulation, endocrinology, acclimation., RFA, Scientific Discipline, Toxics, Waste, Ecosystem Protection/Environmental Exposure & Risk, National Recommended Water Quality, Bioavailability, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, Chemical Mixtures - Environmental Exposure & Risk, Environmental Microbiology, Zoology, Ecological Effects - Environmental Exposure & Risk, Biochemistry, Ecological Effects - Human Health, Ecology and Ecosystems, Ecological Indicators, cell transformation, transport contaminants, endocrine disrupting chemical, toxic metals, endocrine disruptors, Zinc, cellular mechanisms, aquatic ecosystems, amino acids, water quality, cadmium, fish , acclimation processes, rainbow trout

Progress and Final Reports:

  • 1998 Progress Report
  • 1999
  • Final Report