Stress toxique et variations de forme chez "Chironomus riparius" (insecte, diptère)

Abstract : Using traditional and geometric morphometrics, we analysed morphological variations of the mentum and the wings in Chironomus riparius (Insecta, Diptera) exposed to toxic stress. To understand both the causes and mechanisms involved in phenotypic changes, we studied: (1) the relationship between toxic stress, cellular response and shape variations, (2) the pattern of shape variations according to the type of stress: single vs toxic mixture, (3) the evolution of shape variations after metamorphosis and the transmission of the morphological defects to the next generation. To achieve this, Chironomus riparius larvae were exposed during their entire larval life cycle, first to sediment spiked with lead (from 3 to 500 mg/kg dry weight) or 4-NP (from 0 to 200 mg/kg dry weight), second to two sediments sampled in the wild. The first of the latter was characterized by light urban pollution and the other by heavy urban and industrial pollution. We measured the effects of lead on three biochemical markers (energy reserve content, concentrations of metallothionein and cellular damages). Furthermore, for all the bioassays, we assessed shape variations (phenodeviations, fluctuating asymmetry and mean shape changes) of the mentum, a mouthpart structure of the chironomid larvae. For both the sediments sampled in the wild, we also assessed the shape changes of imago wings and the shape changes of the mentum affecting the next generation. At the station where the sediment was characterized by light urban pollution, we also measured morphological variations of the mentum in the Chironomid population belonging to the genus Chironomus. Despite the adverse effects of lead observed at the biochemical level, only slight effects were observed in the mentum shape. Similarly, 4-NP exposure did not induce strong phenotypic defects. On the contrary, mentum deformities increased in Chironomid larvae exposed to slightly contaminated sediment sampled in the wild. This might have been due to the exposure to the toxic mixture. In the heavily contaminated sediment, the low levels of both deformities and fluctuating asymmetry observed might have been the result of selection acting during early developmental stages. This hypothesis could thus explain the increase of developmental instability observed in the next generation placed in a control sediment. In the imago from exposed larvae, no increases in fluctuating wing asymmetry were detected. We observed that the level of morphological variations observed in natural population was similar to that detected in the laboratory in our stock culture reared in the sediment from this station. These results underlined the weak response of the shape biomarkers studied to toxic stress, whether related to multiple toxic exposure or not. Moreover, they highlighted the importance of genetics in shape changes. Consequently, the use of these ontogenic biomarkers as indicators of toxic stress in Chironomus riparius seems to be of limited interest
Document type :
Theses
Complete list of metadatas

https://hal.univ-lorraine.fr/tel-01750091
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 12:37:38 PM
Last modification on : Wednesday, August 29, 2018 - 10:15:14 AM
Long-term archiving on : Friday, September 14, 2018 - 2:08:11 PM

File

DDOC_T_2013_0104_ARAMBOUROU.pd...
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01750091, version 1

Collections

Citation

Hélène Arambourou. Stress toxique et variations de forme chez "Chironomus riparius" (insecte, diptère). Biologie animale. Université de Lorraine, 2013. Français. ⟨NNT : 2013LORR0104⟩. ⟨tel-01750091⟩

Share

Metrics

Record views

53

Files downloads

36