Whole-body regeneration in the colonial tunicate Botrylloides leachii

The colonial marine invertebrate Botrylloides leachii belongs to the Tunicata subphylum, the closest invertebrate relatives to the vertebrate group and the only known class of chordates that can undergo whole-body regeneration (WBR). This dramatic developmental process allows a minute isolated fragment of B. leachii’s vascular system, or a colony excised of all adults, to restore a functional animal in as little as 10 days. In addition to this exceptional regenerative capacity, B. leachii can reproduce both sexually, through a tadpole larval stage, and asexually, through palleal budding. Thus, three alternative developmental strategies lead to the establishment of filter-feeding adults. Consequently, B. leachii is particularly well suited for comparative studies on regeneration and should provide novel insights into regenerative processes in chordates.Here, after a short introduction on regeneration, we overview the biology of B. leachii as well as the current state of knowledge on WBR in this species and in related species of tunicates. Finally, we highlight the possible future directions that research might take in the study of WBR, including thoughts on technological approaches that appear most promising in this context. Overall, we provide a synthesis of the current knowledge on WBR in B. leachii to support research in this chordate species

Ampa (aminomethyl-phosphonic acid) multiple origins in surface water : a new laboratory test

The purpose of this study is to provide information about possible aminomethylphosphonic acid (AMPA) origins. The AMPA found in surface waters is generally considered to be mainly a metabolite of herbicide glyphosate but recent studies indicated other origins in urban areas [1]. In the PIREN Seine programme, the fate of urban pesticides is studied in the Orge River basin, where AMPA is frequently detected in higher concentrations than glyphosate. However, in the literature, it is well documented that AMPA might be also a degradation product of other phosphonates, particularly ethylene-diamine-tetra-methylenephosphonic acid (EDTMPA) and diethylene-triamine-penta-methylene-phosphonic acid (DTMTPA), essentially used in domestic detergents

Atmospheric deposition of PAHs to an urban site, Paris, France

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Ampa (aminomethyl-phosphonic acid) multiple origins in surface water : a new laboratory test

The purpose of this study is to provide information about possible aminomethylphosphonic acid (AMPA) origins. The AMPA found in surface waters is generally considered to be mainly a metabolite of herbicide glyphosate but recent studies indicated other origins in urban areas [1]. In the PIREN Seine programme, the fate of urban pesticides is studied in the Orge River basin, where AMPA is frequently detected in higher concentrations than glyphosate. However, in the literature, it is well documented that AMPA might be also a degradation product of other phosphonates, particularly ethylene-diamine-tetra-methylenephosphonic acid (EDTMPA) and diethylene-triamine-penta-methylene-phosphonic acid (DTMTPA), essentially used in domestic detergents

A Single Law to Describe Atmospheric Nitrogen Bulk Deposition versus Rainfall Amount: Inputs at the Seine River Watershed Scale

International audienceAtmospheric nitrogen species (NH 4-N and (NO 3 +NO 2)-N) were determined in weekly samples of atmospheric bulk deposition (dry plus wet), collected in France at seven sites over the course of a year. Rural, semi-rural and industrialised-urban sites were chosen in the Seine river watershed from the Seine estuary to upstream from Paris. Mean NH 4-N concentrations varied from 0.7 to 1.7 mg L −1. Mean (NO 3 +NO 2)-N concentrations were approximately 0.5 mg L −1 for all sites except Paris (0.7 mg L −1), which has a local impact on the fallout contamination from urban emissions. The relation between concentration and rainfall amount obeys a power law, in the form of y = ax b. When the nitrogen sources are very local, this relationship turns into a dilution law. Annual atmospheric nitrogen deposition (NH 4-N+(NO 3 +NO 2)-N) was calculated and varied from 7.8 kg ha −1 yr −1 in the neighbourhood of a rural town to 17.3 kg ha −1 yr −1 in a very industrialised harbour. 58% of the atmospheric nitrogen deposition occurred during 'spring + summer' period. The total nitrogen atmospheric input to the Seine estuary, via direct deposition + indirect input via the watershed, was estimated to about 5% of the total nitrogen load within the Seine river basin

Atmospheric bulk deposition of PAHs onto France: trends from urban to remote sites

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La contamination de l’Orgeval par les pesticides, une préoccupation de longue date

National audienceLe suivi de la contamination par les pesticides n’est pas aussi simple à mettre en place que pour les nitrates. Pourtant, dès 1975, les premiers travaux ont été menés sur l’Orgeval car la Seine-et-Marne était déjà identifiée comme le département le plus utilisateur de pesticides de tout le bassin de la Seine par l’AFBSN, avec 955 tonnes par an en 1972 (d’après Coyne et Bellier, 1972, cité par Chevreuil, 1978). Les premières analyses montraient une contamination récurrente des eaux par le lindane et dans une moindre mesure par l’heptachlore et l’heptachlore époxyde. Le ru du fossé Rognon à Mélarchez a atteint 0.77 μg/l de lindane en novembre 1976, alors que l’atrazine, dont la présence est essentiellement printanière, atteignait 0,3 μg/l au maximum (Chevreuil, 1978). Cette étude exploratoire a permis de mettre en évidence l’importance de connaître les usages agricoles ainsi que de mieux définir le rôle du drainage agricole dans le transfert des pesticides. Pour cela, il était nécessaire de poursuivre plus en détail des recherches sur ce bassin. De nombreuses études ont donc été réalisées notamment dans le cadre du programme Piren-Seine, alliant des suivis dans le cours d’eau, mais aussi à l’échelle de la parcelle ou de la colonne de sol, en prenant soin de préciser les apports et les processus de transfert mis en jeu

Study of the toxicity of pesticides in the atmosphere of Paris by means of a bioluminescence method.

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