- The nicotinic acetylcholine alpha-subunit gene tar-1 is located on the X chromosome but its coding sequence is not involved in levamisole resistance in an isolate of Trichostrongylus colubriformis. Wiley, L.J., Ferrara, D.R., Sangster, N.C., Weiss, A.S. Mol. Biochem. Parasitol. (1997)









