Copper uptake in adult rainbow trout irradiated during early life stages and in non-irradiated bystander trout which swam with the irradiated fish

Abstract

Purpose

This investigation forms part of a wider study into the legacy effects of exposure of rainbow trout eggs 38 h after fertilization, eyed eggs, yolk sac larvae (YSL) or first feeders to a single 0.5 Gy X-ray dose, including the induction of a bystander effect, by the irradiated fish, to non-irradiated fish. Fish may be exposed to multiple environmental stressors, including waterborne metals, during their lifespan and, while there are data on how the legacy of early life stage irradiation and bystander effect induction is affected by waterborne aluminum and cadmium, there are no studies into the effects radiation or the radiation induced bystander effect on metal uptake. Therefore the aim of this investigation was to determine if the legacy of early life stage irradiation included an effect on copper uptake by adult fish and by non-irradiated bystander adult trout which swam with the irradiated fish.

Methods

The four early life stages mentioned above were exposed to a single 0.5 Gy X-ray dose and then maintained, for two years with no further irradiation. At two years old the irradiated fish were allowed to swim, for 2 h with non-irradiated bystander trout (also two years old). After this time copper uptake was determined using ⁶⁴Cu.

Results

Copper uptake was increased in adult trout irradiated as eggs at 48 h after fertilization and as first feeders but eyed egg or YSL irradiation had no effect. Copper uptake was also increased in the bystander trout which swam with trout irradiated as eggs at 48 h after fertilization and as eyed eggs but there was no effect on non-irradiated adult trout which swam with trout irradiated as YSL or first feeders.

Conclusions

When put in context with the proteomic changes observed in these fish we propose the increased copper uptake in adult trout irradiated as eggs at 48 h after fertilization could be part of an anti-tumorigenic response and the increase in copper uptake in adult trout irradiated as first feeders could be part of a potentially protective pro-apoptotic response. Similarly we propose the increase in copper uptake in non-irradiated adult trout, induced by trout irradiated as eggs at 48 h after fertilization or as eyed eggs, was part of the universally anti-tumorigenic nature of the X-ray induced bystander effect in fish. However this was exclusive to embryonic irradiation.

Keywords:

• Bystander effect
• copper uptake
• early life stage irradiation
• rainbow trout

Acknowledgements

The authors express our grateful thanks to Michael Burke, David Bevan, Michael Kirk and Neil MacBeth, Alma Aquaculture Research Station, University of Guelph, for the initial breeding, rearing and husbandry of all the fish used in this investigation.

Disclosure statement

The authors report no conflict of interest. The authors alone are responsible for the content and writing of this paper.

Additional information

Funding

Funding for this investigation was provided by; Natural Sciences and Engineering Research Council (NSERC) (RGPIN06223-17 and RPGIN05542-14), Industrial Chairs Programme, Canada Deuterium Uranium (CANDU) Owners Group, Bruce Power and The Canada Chairs Programme. All procedures used in this investigation were carried out in accordance with the animal care protocols and regulatory guidelines imposed by McMaster University Central Animal Care Facility and by the University of Guelph, and were specifically covered by McMaster Animal Utilisation Protocol (AUP) 06-12-65.

Notes on contributors

Richard Smith

Richard Smith is a fish physiologist with a particular interest in proteomics.

Sunita Nadella

Sunita Nadella is an experimental education coordinator but her research interests include environmental physiology and toxicology.

Richard Moccia

Richard Moccia is a retired professor of aquatic and fisheries science. He held both senior faculty and executive cross-appointments as the Associate Vice President, Research at the University of Guelph over a 34 year career, and published widely in the fields of physiology, pathology, nutrition, environmental and welfare sciences.

Colin Seymour

Colin Seymour is a Professor at McMaster University. His interests include low dose radiobiology, non-targeted effects and environmental effects of radiation.

Carmel Mothersill

Carmel Mothersill is a Professor and Canada Research Chair in radiation biology at McMaster University. Her research interests include multiple stressor research and low dose radiation effects.