Irradiation of rainbow trout at early life stages results in legacy effects in adults.
OBJECTIVE
Communication of signals from irradiated to non-irradiated fish has been demonstrated by our group for adults. Major questions are however, whether the effects persist for significant lengths of time (meaning there are memories or legacies of the exposure) and whether they are induced in young animals or very early stages in the life cycle.


METHODS
To address these questions we used a reporter cell clonogenic bioassay to detect the effects of radiation exposure and of 'bystander' signals, emitted from irradiated fish, on non-irradiated fish. The legacy of radiation exposure or receipt of bystander signals was investigated in rainbow trout irradiated as eggs at 48 h, eyed eggs at one month, yolk sac larvae (YSL) at two months and juveniles at three months after fertilisation. The irradiated and bystander fish together with shams and unhandled husbandry controls were grown on in a hatchery and examined as they reached each of the remaining life stages. They were also re-examined as one-year-olds with and without further irradiation and finally examined as sexually mature two-year-olds.


RESULTS
The data indicate a clear legacy effect of irradiation at any early life stage in the adult fish.


CONCLUSIONS
The data suggest that bystander signals can be transmitted in vivo and once induced are persistent during the animals' lifespan.
Mothersill
Carmel
C
Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada. mothers@mcmaster.ca
Smith
Richard W
RW
Saroya
Rohin
R
Denbeigh
Janet
J
Rowe
Britni
B
Banevicius
Laura
L
Timmins
Rachel
R
Moccia
Richard
R
Seymour
Colin B
CB
D000818:Animals; D024201:Bystander Effect / Q000528:radiation effects*; D008018:Life Cycle Stages / Q000528:radiation effects*; D017686:Oncorhynchus mykiss / Q000254:growth & development*; D013997:Time Factors