title: Ovarian cycle and embryonic development in Gammarus fossarum: application for reproductive toxicity assessment.
abstract: Among freshwater invertebrates, Gammarus fossarum is an important test organism and is currently used in ecotoxicology for acute and chronic assays; nevertheless, reproductive toxicity test methods are not yet available for these species. In the present study, the reproductive cycle in Gammarus fossarum was characterized in order to propose a reproductive toxicity test encompassing molting, follicle growth, and embryonic development that will provide a better understanding of the mode of action of chemicals disrupting these hormone-regulated processes. A detailed description of the reproductive cycle in Gammarus fossarum was obtained. As in some amphipods, molt and reproductive cycles of G. fossarum females occur concurrently, lasting 30 d at 12°C. Each molt stage is characterized by a specific marsupial embryonic development stage and the size of developing follicles visible on the ovarian membrane. Based on these results, a 21-d reproductive toxicity test is proposed for this species. This new bioassay was applied to identify the specific impact of different stressors: cadmium, methomyl, nonylphenol, and a starvation diet. Good reproducibility was obtained for different endpoints under control conditions and throughout the experiments. Preliminary robust reference values or benchmarks were proposed for these endpoints. Cadmium was found to specially inhibit secondary vitellogenesis. Nonylphenol had a specific concentration-dependent effect on embryonic development, with an increase in the percent abnormality from a concentration of 0.05 µg/L. A restricted food diet led to a significant delay in the molt cycle, which in turn induced inhibition of secondary vitellogenesis.
authors.affiliation: Cemagref, Unité de Recherche des Milieux Aquatiques (UR MALY), 3 bis quai Chauveau-CP 220, F-69336 Lyon, France. olivier.geffard@cemagref.fr
authors.forename: Olivier
authors.initials: O
authors.lastname: Geffard
authors.forename: Benoit
authors.initials: B
authors.lastname: Xuereb
authors.forename: Arnaud
authors.initials: A
authors.lastname: Chaumot
authors.forename: Alain
authors.initials: A
authors.lastname: Geffard
authors.forename: Sylvie
authors.initials: S
authors.lastname: Biagianti
authors.forename: Claire
authors.initials: C
authors.lastname: Noël
authors.forename: Khedidja
authors.initials: K
authors.lastname: Abbaci
authors.forename: Jeanne
authors.initials: J
authors.lastname: Garric
authors.forename: Guy
authors.initials: G
authors.lastname: Charmantier
authors.forename: Mireille
authors.initials: M
authors.lastname: Charmantier-Daures
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian; D005260:Female; D007448:Invertebrates / Q000196:embryology / Q000502:physiology*; D015203:Reproducibility of Results; D012098:Reproduction / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical