Host specificity is predicted to shape patterns of parasite gene flow between host species; specialist parasites should have low gene flow between host species, while generalists are predicted to have high gene flow between species. However, even for generalist parasites external forces, including ecological differences between host species may sometimes intervene to limit gene flow and create ...

Gastrointestinal (GI) tract leucine metabolism was measured in 6- to 9-mo-old lambs subjected to trickle infection with Trichostrongylus colubriformis larvae and in separate animals that were not infected. Animals prepared with a jejunal catheter and with indwelling catheters into the aorta and the portal- (PDV) and mesenteric- (MDV) drained viscera were infused simultaneously with [1-13C] and ...

The anthelmintic activity of Markhamia obtusifolia Sprague (Bignoniaceae) leaf extracts was evaluated against the ruminant gastrointestinal nematode parasite Trichostrongylus colubriformis (Nematoda: Strongylida) using the in vitro egg hatch test. Also, the cytotoxic activity of aqueous extracts of M. obtusifolia was evaluated in cell line cytotoxicity assays. The results indicated that the eff...

Cyclotides are a large family of cyclic cystine knot-containing plant peptides that have anthelminthic activities against Haemonchus contortus and Trichostrongylus colubriformis, two important gastrointestinal nematodes of sheep. In this study, we investigated the interaction of the prototypic cyclotide kalata B1 with the external surface of H. contortus larvae and adult worms. We show that cyc...

Anthelmintic resistance has emerged as an important problem in animal industries. Understanding resistance mechanisms, especially against macrocyclic lactones (MLs), is the first step in developing better diagnostic tools. Effects of several MLs including ivermectins and milbemycins were tested using two well established in vitro assays: the larval development assay (LDA) and the larval migrati...

Recent epidemiological observations from field studies indicated that sheep selected for resistance to digestive nematodes were more infected than susceptible ones with the nasal bot fly, Oestrus ovis. The present study was undertaken to verify these informations and to explore the possible associated mechanisms. After a whole grazing season and an anthelmintic drench, two groups of 6 rams belo...

Goat production is widespread in the tropics. Goats are very susceptible to gastrointestinal nematode infection, but there is less evidence of their genetic resistance. Genetic resistance of Creole goats to gastrointestinal nematodes has been studied at Guadeloupe in the French West Indies since 1995. The objective of this research was to investigate genetic variation for resistance to gastroin...

Cyclotides are a family of macrocyclic peptides that combine the unique features of a head-to-tail cyclic backbone and a cystine knot motif, the combination of which imparts them with extraordinary stability. The prototypic cyclotide kalata B1 is toxic against two economically important gastrointestinal nematode parasites of sheep, Haemonchus contortus and Trichostrongylus colubriformis. A lysi...

The discovery of novel drugs against animal parasites is in high demand due to drug-resistance problems encountered around the world. Herein, the synthesis and characterization of 27 organic and organometallic derivatives of the recently launched nematocidal drug monepantel (Zolvix® ) are described. The compounds were isolated as racemates and were characterized by 1 H, 13 C, and 19 F NMR spect...

This study was carried out to evaluate the immune response in young Ile de France (IF) and Santa Ines (SI) sheep naturally infected by Oestrus ovis and gastrointestinal nematodes (GIN). Mast cells, eosinophils and globule leucocytes were enumerated in the upper respiratory tract (septum, middle meatus and ventral nasal conchae) and in the mucosa of abomasum and small intestine. Immunoglobulin G...