title: DNA alterations and effects on growth and reproduction in Daphnia magna during chronic exposure to gamma radiation over three successive generations.
abstract: This study examined chronic effects of external Cs-137 gamma radiation on Daphnia magna exposed over three successive generations (F0, F1 and F2) to environmentally relevant dose rates (ranging from 0.007 to 35.4 mGy h(-1)). Investigated endpoints included survival, growth, reproduction and DNA alterations quantified using random-amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). Results demonstrated that radiation effects on survival, growth and reproduction increased in severity from generation F0 to generation F2. Mortality after 21 days at 35.4 mGy h(-1) increased from 20% in F0 to 30% in F2. Growth was affected by a slight reduction in maximum length at 35.4 mGy h(-1) in F0 and by reductions of 5 and 13% in growth rate, respectively, at 4.70 and 35.4 mGy h(-1) in F2. Reproduction was affected by a reduction of 19% in 21 day-fecundity at 35.4 mGy h(-1) in F0 and by a delay of 1.9 days in brood release as low as 0.070 mGy h(-1) in F2. In parallel, DNA alterations became significant at decreasing dose rates over the course of F0 (from 4.70 mGy h(-1) at hatching to 0.007 mGy h(-1) after ∼21 days) and from F0 to F2 (0.070 mGy h(-1) at hatching to 0.007 mGy h(-1) after ∼21 days), demonstrating their rapid accumulation in F0 daphnids and their transmission to offspring generations. Transiently more efficient DNA repair leading to some recovery at the organism level was suggested in F1, with no effect on survival, a slight reduction of 12% in 21 day-fecundity at 35.4 mGy h(-1) and DNA alterations significant at highest dose rates only. The study improved our understanding of long term responses to low doses of radiation at the molecular and organismic levels in a non-human species for a better radioprotection of aquatic ecosystems.
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Parisot
authors.affiliation: UMR 5805 EPOC - OASU, Station marine d'Arcachon, Université Bordeaux 1, Arcachon 33120, France.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Bourdineaud
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Plaire
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Adam-Guillermin
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115, France. Electronic address: frederic.alonzo@irsn.fr.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Alonzo
mesh_terms: D000818:Animals; D049628:Body Size / Q000528:radiation effects; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects*; D003621:Daphnia / Q000254:growth & development / Q000528:radiation effects*; D005720:Gamma Rays; D012098:Reproduction / Q000528:radiation effects*
chemical_list: D004247:DNA
keywords: DNA alterations; Daphnia magna; Gamma radiation; Growth; Reproduction; Transgenerational effects