Motility affected by cyclotides
The effects of cyclotides on the adult stages of H. contortus were assessed by observing the degree of motility shown by worms over a period of exposure to the peptides in vitro. The cyclotides were added at various concentrations to assay tubes containing adult worms and the tubes were kept at 37 °C. Each compound was tested in triplicate. At 24 h intervals, the worms were observed and their degree of motility was scored. The assay tubes were placed onto a warm tray, and tubes were held individually near a light for assessment of motility. Each tube was swirled to thoroughly disturb the nematodes and was scored according to the degree of motility shown by the worms using the scoring system described by OGrady and Kotze. Briefly, the worms were scored as: 3: most individuals showing significant smooth sinusoidal motion, similar to motion at the start of the culture period; 2: significant movement shown by a small number of individuals, at least one individual able to move in a normal sinusoidal fashion; 1: only very limited movement in a small number of individuals, no sinusoidal motion; 0: no movement.
Although the limited number of concentrations and the subjective step-wise nature of the scoring system does not allow ready quantification of differences between the activities of the peptides, it was apparent that after 48 h a motility score of 1 was associated with <4, 4 and approximately 20 M for cO2, cO14 and kB1, respectively.