Soil is the origin for the presence of Naegleria fowleri in the thermal recreational waters

International audienceNaegleria fowleri is found in most geothermal baths of Guadeloupe and has been responsible for the death of a 9-year-old boy who swam in one of these baths in 2008. We wanted to determine the origin for the presence of this amoeba in the water.Water samples were taken at the origin of the geothermal sources and at the arrival in the baths. After filtration, cultures were made and the number of Naegleria present was determined using the most probable number method. Soil samples collected in the proximity of the baths were also tested for the presence of thermophilic amoebae. The species identification was obtained by PCR. During three consecutivemonths, no Naegleria could be found at the origin of any geothermal source tested. In contrast, N. fowleri was isolated at least once in all baths at the arrival of the water, except one. Thermophilic amoebae could be found in each soil sample, especially near the baths located at a lower altitude, but N. fowleri was only isolated near two baths, which were also the baths most often contaminated with this species. So it appears that the contamination of the water with N. fowleri occurs after emerging from the geothermal source when the water runs over the soil. Therefore, it should be possible to reduce the concentration of N. fowleri in thegeothermal baths of Guadeloupe to for example less than 1 N. fowleri/10 L by installing a pipeline between the geothermal sources and the baths and by preventing flooding water from entering the baths after rainfall. By taking these measures, we were able to eliminate N. fowleri from a poollocated inside a reeducation clinic

Can UV radiation and cadmium exposures induce tumors in freshwater invertebrates ?

International audienceBecause ecosystems on our planet are now polluted by mutagenic substances to a greater extent than ever before, it is increasingly suggested that human activities are oncogenic for wildlife species. To improve our knowledge on these timely issues, experimental evidence should however complete correlative field studies. Hydras and Planarians are freshwater invertebrates which sometimes develop tumors. Hydras tumors are able to be vertically transmitted during asexual reproduction. Because the etiology of these atypical tumors is unknown, our objective is to explore the extent to which they could be, at least partially, linked to human activities. Specifically, this project aims at testing if UV radiation (both UV-A and UV-B) and/or cadmium exposure can promote tumorigenesis, and to evaluate how transmissible these inducible tumors are. A second objective is to explore the extent to which UV & cadmium exposures induce tumors in planarians. This project not only represents an original contribution to the field of ecology in human-altered habitats, but also improves our knowledge on the evolutionary ecology of transmissible malignant cell lines, and host-tumor interactions

A review of the methods used to induce cancer in invertebrates to study its effects on the evolution of species and ecosystem functioning

International audience1. Cancer is an understudied but important process in wildlife that is predicted to have a significant effect on the evolution of metazoan species due to negative effects on host fitness. However, gaining understanding of the impact of cancer on species and ecosystems is currently relatively slow as the development of both animal models in which cancer can be induced and experiments that can be performed in an ecological setting are required. Invertebrates, because they are widely available and relatively easy to manipulate, are promising animal models. In this review we examine how tumours can be induced in invertebrates to use them as experimental models to study the effects of cancer on the ecology and evolution of species. We identified four main groups of invertebrates (planarian, bivalves, hydra and drosophila) in which such inductions are performed. We then reviewed the types and effectiveness of the methods employed to induce tumours in those groups. Cancer alters the phenotype of the host. We review how experiments using invertebrate models can be used to investigate the impact of cancer on tumour-bearing individuals for their movement, reproduction, feeding behaviours, social interactions, holobiont and predation risk.We provide recommendations to facilitate the development of new invertebrate models. We also highlight a series of key questions on the ecology and evolution of cancer that could be answered with the use of invertebrate models