Fatty acids, especially those from phospholipids (PLFA), are essential membrane components that are present in relatively constant proportions in biological membranes under natural conditions. However, under harmful growth conditions, such as diseases, environmental changes, and chemical exposure, the fatty acid proportions might vary. If such changes could be identified and revealed to be specific for adverse situations, they could be used as biomarkers. Such biomarkers could facilitate the identification of virulence and resistance mechanisms to particular chemotherapeutic agents. Therefore, specific biomarkers could lead to better therapeutic decisions that would, in turn, enhance treatment effectiveness. The objective of this study was to compare the fatty acid profiles of trivalent antimony and nitric oxide (NO)-resistant and -sensitive Leishmania chagasi and Leishmania amazonensis isolates. Fatty acid methyl esters (FAMEs) were obtained from total lipids (MIDI), ester-linked lipids (ELFA), and ester-linked phospholipids (PLFA). FAMEs were analyzed by chromatography and mass spectrometry. Species- or resistance-associated differences in FAME profiles were assessed by nonmetric multidimensional scaling, multiresponse permutation procedures, and indicator species analyses. The isolate groups had different MIDI-FAME profiles. However, neither the ELFA nor PLFA profiles differed between the sensitive and resistant isolates. Levels of the fatty acid 18:1 Δ9c were increased in sensitive isolates (p < 0,001), whereas the fatty acid 20:4 Δ5,8,11,14 showed the opposite trend (p < 0.01). We conclude that these two fatty acids are potential biomarkers for NO and antimony resistance in L. chagasi and L. amazonensis and that they could be helpful in therapeutic diagnoses.

Trois groupes de brebis sont inséminées artificiellement à l’aide de doses de semence (congelées au printemps) contenant 100 x 106 spermatozoïdes dans un volume de 0,5 ml, après synchronisation de l’oestrus et d'injections de P.M.S.G. Les 28 brebis du 1er groupe (T1) sont inséminées par voie intracervicale profonde (une seule intervention réalisée 55 h après le retrait de l'éponge vaginale). Les 32 brebis du 2e groupe (T2) sont inséminées également par voie intracervicale profonde (2 interventions réalisées respectivement 48 et 60 h après le retrait de l’éponge vaginale). Les 28 brebis du 3e groupe (T3) sont inséminées par voie cervicale superficielle (2 interventions réalisées respectivement 48 et 60 h après le retrait de l’éponge vaginale). Les résultats de non-retour en chaleurs à 21 Jours, fertilité, fécondité et prolificité sont les suivants : T1 (60,7 % ; 60,7 % ; 92,8 % ; 152,9*%) -T2 (56,6 % ; 46,6 % ; 83,3 % ; 178,5 %) -T3 (32,1 % ; 25,0 % ; 25,0 % ; 100,0 %).