Communication of Radiation-Induced Stress or Bystander Signals between Fish in Vivo

Abstract

We report data in this paper suggesting that fish irradiated to 0.5 Gy total body dose can release factors into the water that signal other unexposed fish and cause induction of bystander effects expressed as increased cell death in a reporter system. Radiation-induced bystander effects, resulting in the appearance of radiation damage or induction of typical radiation responses in unirradiated cells and tissues are now an established consequence of exposure to low doses of ionizing radiation, however little work has been done in vivo or in species other than humans or mice. In these experiments rainbow trout were irradiated and then paired with unirradiated fish for two hours. Additionally, unirradiated fish were placed in water which had previously been used to hold irradiated fish for 2 h. Sham-irradiated fish and absolute control fish were also examined all using blind protocols. Following a two h incubation period, at these various exposure regimes, the fish were killed by a blow to the head and dissected. Five organs were removed from each fish and tissue explants were cultured using an established technique. After 2 days, the culture medium was harvested and used in a reporter assay to determine whether a bystander effect had been induced. The explants were cultured on in Clonetics growth medium for a further 14 days then fixed for assay of radiation response proteins. The responses varied according to the cell type in the original explants, with the gill and fin showing the most pronounced response. The results suggest that communication signals leading to a typical radiation response can be passed between fish and seem to involve secretion of a chemical messenger into the water.

Radiation Induced Bystander effects in Mice given Low Doses of Radiation in vivo

“…These findings have been previously reported by various groups such as Mothersill et al (2005Mothersill et al ( , 2006Mothersill et al ( , 2007 and O 'Dowd et al (2006) which have shown the production of bystander factor(s) after in vivo and in vitro irradiation of various species of mice and fish.…”

A preclinical microbeam facility with a conventional x‐ray tube

“…Manifold evidence indicates that blood vessels and their different repair efficiencies in malignant and healthy tissue are essential to explain the differential effect of microbeams 2 , 4 , 5 , 13 . Apart from that experiments demonstrate that bystander signals, 14 , 15 changes in the immune response, DNA repair, and variations in the cell cycle 16 are important for the biological response to MRT.…”

Short and long term bystander effect induction by fathead minnows (Pimephales promelas, Rafinesque, 1820) injected with environmentally relevant whole body doses of 226Ra

“…a tissue in direct contact with any radiation induced bystander signal present in the water) was then removed at the peduncle and placed in ice cold L15 tissue culture medium. Explant cultures of these fin samples were made by firstly incubating segments of tissue (approximately 1 mm 2 ) in 0.25% w/v trypsin (Gibco, Biocult, Irvine, Scotland) for 30 min at 19 C. After trypsin treatments the tissue segments were placed in the centre of T25 cell culture flasks (NUNC, Uden, Denmark) in 2 ml RPMI-1640, supplemented as described (Mothersill et al, 2006). These explants were then incubated for 48 h at 19 C. After 48 h the explant media was collected, filtered and transferred to cultures of the HPV-G reporter cells.…”

“…There is now an increasing amount of data to show that fish, when irradiated with low doses of radiation, are able to induce a bystander effect in non-irradiated fish. Predominantly this research has been carried out using 0.5 Gy X-ray irradiation (Mothersill et al, 2012(Mothersill et al, , 2009(Mothersill et al, , 2007(Mothersill et al, , 2006Saroya et al, 2010;Smith et al, 2013Smith et al, , 2011. X-rays have the advantage of not making the irradiated fish radioactive.…”