title: Biological effects of α-radiation exposure by (241)Am in Arabidopsis thaliana seedlings are determined both by dose rate and (241)Am distribution.
abstract: Human activity has led to an increasing amount of radionuclides in the environment and subsequently to an increased risk of exposure of the biosphere to ionising radiation. Due to their high linear energy transfer, α-emitters form a threat to biota when absorbed or integrated in living tissue. Among these, (241)Am is of major concern due to high affinity for organic matter and high specific activity. This study examines the dose-dependent biological effects of α-radiation delivered by (241)Am at the morphological, physiological and molecular level in 14-day old seedlings of Arabidopsis thaliana after hydroponic exposure for 4 or 7 days. Our results show that (241)Am has high transfer to the roots but low translocation to the shoots. In the roots, we observed a transcriptional response of reactive oxygen species scavenging and DNA repair pathways. At the physiological and morphological level this resulted in a response which evolved from redox balance control and stable biomass at low dose rates to growth reduction, reduced transfer and redox balance decline at higher dose rates. This situation was also reflected in the shoots where, despite the absence of a transcriptional response, the control of photosynthesis performance and redox balance declined with increasing dose rate. The data further suggest that the effects in both organs were initiated in the roots, where the highest dose rates occurred, ultimately affecting photosynthesis performance and carbon assimilation. Though further detailed study of nutrient balance and (241)Am localisation is necessary, it is clear that radionuclide uptake and distribution is a major parameter in the global exposure effects on plant performance and health.
authors.affiliation: SCK⋅CEN, Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium; Centre for Environmental Research, Universiteitslaan 1, 3590 Diepenbeek, Belgium. Electronic address: geert.biermans@fanc.fgov.be.
authors.forename: Geert
authors.initials: G
authors.lastname: Biermans
authors.affiliation: SCK⋅CEN, Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium.
authors.forename: Nele
authors.initials: N
authors.lastname: Horemans
authors.affiliation: SCK⋅CEN, Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vanhoudt
authors.affiliation: SCK⋅CEN, Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium.
authors.forename: Hildegarde
authors.initials: H
authors.lastname: Vandenhove
authors.affiliation: SCK⋅CEN, Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium; Centre for Environmental Research, Universiteitslaan 1, 3590 Diepenbeek, Belgium.
authors.forename: Eline
authors.initials: E
authors.lastname: Saenen
authors.affiliation: SCK⋅CEN, Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium.
authors.forename: May
authors.initials: M
authors.lastname: Van Hees
authors.affiliation: SCK⋅CEN, Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium.
authors.forename: Jean
authors.initials: J
authors.lastname: Wannijn
authors.affiliation: Centre for Environmental Research, Universiteitslaan 1, 3590 Diepenbeek, Belgium.
authors.forename: Jaco
authors.initials: J
authors.lastname: Vangronsveld
authors.affiliation: Centre for Environmental Research, Universiteitslaan 1, 3590 Diepenbeek, Belgium.
authors.forename: Ann
authors.initials: A
authors.lastname: Cuypers
mesh_terms: D000512:Alpha Particles / Q000009:adverse effects*; D000576:Americium / Q000633:toxicity*; D000975:Antioxidants / Q000378:metabolism / Q000528:radiation effects*; D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D018384:Oxidative Stress / Q000528:radiation effects; D010788:Photosynthesis / Q000528:radiation effects; D018517:Plant Roots / Q000378:metabolism / Q000528:radiation effects; D018520:Plant Shoots / Q000378:metabolism / Q000528:radiation effects; D014158:Transcription, Genetic / Q000528:radiation effects*
chemical_list: D000975:Antioxidants; D000576:Americium
keywords: Abiotic stress; Americium-241; Arabidopsis thaliana; Biological effects; Gene expression