Ultrastructural changes in the third-stage, infective larvae of ruminant nematodes treated with sainfoin (Onobrychis viciifolia) extract
2011
Brunet, Séverine | Fourquaux, Isabelle | Hoste, Herve | Interactions hôtes-agents pathogènes [Toulouse] (IHAP) ; Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Vétérinaire de Toulouse (ENVT) ; Institut National Polytechnique (Toulouse) (Toulouse INP) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National Polytechnique (Toulouse) (Toulouse INP) ; Université de Toulouse (UT)-Université de Toulouse (UT) | Centre de Microscopie Électronique Appliquée à la Biologie (CMEAB) ; Toulouse Réseau Imagerie-Genotoul (TRI-Genotoul) ; Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | This work received financial support from the European Union as part of the Marie-Curie project "Healthy Hay" (Project number: MRTN_CT-2006-035805). The financial support of the Region Midi-Pyrenees (contract 030121196) is also sincerely acknowledged. Special thanks are due to Dr. I. Mueller-Harvey of the University of Reading for helpful comments on the manuscript and to Mrs D. Goodfellow to revise the English version of the article.
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Show more [+] Less [-]English. Plants rich in condensed tannins are an alternative to chemical anthelmintics to control gastrointestinal nematodes (GINs) in ruminants. Previous functional studies have shown that sainfoin extracts affect the two forms of infective larvae (L3), ensheathed and exsheathed. However, the mechanisms of action remain unknown. The aim of this study was thus to compare ultrastructural changes in ensheathed and exsheathed 13 of two GIN species after in vitro contact with sainfoin extracts using transmission electron microscopy. The main changes identified were an alteration of the hypodermis, the presence of numerous vesicles in the cytoplasm and degeneration and/or death of muscular and intestinal cells. The changes suggested similar and nonspecies-specific lesions in the two nematode species. Comparison of the modifications found in the ensheathed vs. exsheathed L3s revealed different locations of the main cellular changes depending on the larval form. It is hypothesized that these spatial differences in lesions are mainly influenced by the presence of the sheath which favors contact between the active compounds and either the cuticle or the digestive tract. Overall, our observations suggest that the functional changes observed in the biology of GIN Us after contact with sainfoin extracts are mediated through a direct mode of action, i.e. different interactions between the bioactive plant metabolites and the nematode structure depending on the route of contact.
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