Invertébré | EPFL Graph Search

Un invertébré est un animal dépourvu de colonne vertébrale et d'os en général. Définis jadis comme un embranchement par opposition aux Vertébrés, les Invertébrés forment en réalité un groupe paraphylétique et, de ce fait et au regard des critères actuels de classification, ne sont plus considérés comme un taxon admis au sein de la classification du vivant. Un ancien terme de classification, aujourd’hui remis en cause Quelques invertébrés. La distinction entre les Invertébrés (Invertebrata) et les Vertébrés (Vertebrata, auxquels appartient Homo sapiens) est due au naturaliste français Jean-Baptiste de Lamarck dans son Discours d'ouverture du cours des animaux sans vertèbres en 1806 et dans son Histoire naturelle des animaux sans vertèbres (1815-1822). Si les vertébrés forment un ensemble cohérent issus d'un ancêtre commun, les « invertébrés » sont au contraire un ensemble hétéroclite d'espèces dont certaines (comme les échinodermes ou l'amphioxus) sont plus ou moins

Imaging neural activity in the ventral nerve cord of behaving adult Drosophila

Florian Aymanns, Chin-Lin Chen, Denis Fortun, Laura Joan Hermans, Pavan P Ramdya, Michaël Unser

To understand neural circuits that control limbs, one must measure their activity during behavior. Until now this goal has been challenging, because limb premotor and motor circuits have been largely inaccessible for large-scale recordings in intact, moving animals-a constraint that is true for both vertebrate and invertebrate models. Here, we introduce a method for 2-photon functional imaging from the ventral nerve cord (VNC) of behaving adult Drosophila melanogaster. We use this method to reveal patterns of activity across nerve cord populations during grooming and walking and to uncover the functional encoding of moonwalker ascending neurons (MANs), moonwalker descending neurons (MDNs), and a previously uncharacterized class of locomotion-associated A1 descending neurons. Finally, we develop a genetic reagent to destroy the indirect flight muscles and to facilitate experimental access to the VNC. Taken together, these approaches enable the direct investigation of circuits associated with complex limb movements.

2018

Endocrine disruption in soil invertebrates

Sophie Campiche

In the past years, it has been observed that some compounds present in our environment can disturb the reproduction and development of animals like fishes, birds, or reptiles by interfering with their endocrine system. Indeed, these endocrine disrupting compounds (EDC) can mimic or antagonize the effects of hormones, alter the pattern of synthesis and metabolism of hormones or modify hormone receptor levels. These substances represent a risk for wildlife, and possibly for humans. Up to now, endocrine disruption was mainly evaluated for vertebrates and aquatic organisms and for oestrogeniclike substances. However, soil invertebrates, which play an important role in soil functioning, have rarely been considered. Moreover, as their endocrine system differs substantially from those of vertebrates (estrogens do not seem to regulate endocrine functions in invertebrates), other substances than can mimic invertebrate hormones should be taken into account. In this sense, insect growth regulators (IGR), which are third generation insecticides specially developed to interfere with insect endocrine system, are interesting compounds. These substances are supposed to have a high specificity for insect pest and a low toxicity for non-target organisms. In the first part of this study, the sublethal effects of six IGR (methoprene, fenoxycarb, precocene II, tebufenozide, hexaflumuron and teflubenzuron) were evaluated on the non-target soil arthropod Folsomia candida. The collembola F. candida represents an integral and beneficial part of the soil ecosystem. It is an euedaphic (subsurface) species which plays an important role in soil respiration and decomposition processes and is therefore vulnerable to the effects of soil contamination. This ecologically relevant organism is one of the most appropriate invertebrate test species for the assessment of environmental quality. It is recommended as test organism by the international standard ISO 11267. The 28-days reproduction tests conducted according to this protocol show that F. candida is affected by the chosen IGR. The most toxic compounds were the two chitin synthesis inhibitors, teflubenzuron and hexaflumuron, with an EC50 of 0.05 mg/kg (dw) for teflubenzuron and an EC50 of 0.6 mg/kg for hexaflumuron. These concentrations are probably environmentally relevant (toxicity/exposure ratios

EPFL2006

Bioaccumulation of antibiotics in wild freshwater invertebrates

Marc Chevreuil, Luiz Felippe De Alencastro

Occurrence and bioaccumulation of 20 antibiotics, including fluoroquinolones (FQs), sulfonamids (SAs), macrolids (MLs), tetracyclins (TCs),diaminopyrimidins (DPs) and nitro-imidazols (NIs) in an amphipod crustacean (Gammarus pulex) inhabiting in the small river, downstream of effluent from a wastewater treatment plants in Ile-de-France (France) and in shrimps (Lipopenaeus vannamei) inhabiting in the rivers surrounding of intensive shrimp farmingsfarming in the Delta Mekong - Vietnam were investigated. Surface water, sediment and invertebrates samples were analyzed by HPLC-MS/MS. Sulfamethoxazole, ciprofloxacine, ofloxacine and norfloxacine, were found in all surface water samples in both research studied areas. However, in France, SAs were the predominant antibiotics in surface water with the maximum concentration of 2780 ng/l for sulfamethoxazole, while, in Vietnam, FQs were the predominant antibiotics with the maximum concentration of 200 ng/l for ciprofloxacin. In sediment samples of both research areas, FQs were the most frequently detected with concentrations from a few to several hundreds µg/kg. The high concentrations and detection frequencies of FQs in sediments indicate that sediments are an important reservoir for FQs as they are strongly adsorbed on to sedimentsit. In the Gammarus pulex, six antibiotics (nalidixic acid, ciprofloxacin, ofloxacin, norfloxacin, flumequin and trimethoprim) were detected with the concentration rangedge from 2 - to 106 µg/kg (dry weight). Concentration in juvenile were higher than in adult and a seasonal effect was observed during the study period, this variation is however of lower amplitude in juvenile. In the shrimps Lipopenaeus vannamei, ciprofloxacin, norfloxacin, erythromycin and sulfamethoxazole were detected with the concentrations ranged from 4 - to 160 µg/kg. These results shown that antibiotics are weakly bioaccumulated with respect to environmental contamination and that , there is a correlation between the adsorption of antibiotics in sediments and their accumulation in wild freshwater invertebrates. The molecular profiles and the concentrations in the invertebrates were depending on species and habitat.

2017