title: Nitrogen excretion by the sheep abomasal parasite Teladorsagia circumcincta.
abstract: Excretion of nitrogenous substances by Teladorsagia circumcincta was investigated during incubation of L3 in phosphate buffer for up to 30h and adult worms for 4-6h. Ammonia was the main excretory product, with about 20% urea. For the first 4-6h, ammonia excretion by L3 was temperature dependent, directly proportional to the number of larvae, but independent of the pH or strength of the phosphate buffer. Later, ammonia excretion slowed markedly in L3 and adults and reversed to net uptake in L3 by 30h. An initial external ammonia concentration of 600 microM did not alter the pattern or magnitude of excretion. Re-uptake of ammonia did not occur at extremes of pH or low buffer strength and was slightly reduced at the highest external concentrations. Ammonium transporters and enzymes of glutamate metabolism, including glutamate dehydrogenase, glutamine synthetase and possibly glutamate synthase, are worthy of further investigation as anthelmintic targets.
authors.affiliation: Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand. H.V.Simpson@massey.ac.nz
authors.forename: H V
authors.initials: HV
authors.lastname: Simpson
authors.forename: N
authors.initials: N
authors.lastname: Muhamad
authors.forename: L R
authors.initials: LR
authors.lastname: Walker
authors.forename: D C
authors.initials: DC
authors.lastname: Simcock
authors.forename: S
authors.initials: S
authors.lastname: Brown
authors.forename: K C
authors.initials: KC
authors.lastname: Pedley
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D015801:Helminth Proteins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000378:metabolism; D017672:Nitrogen Compounds / Q000378:metabolism*; D012756:Sheep; D013696:Temperature; D014251:Trichostrongyloidea / Q000378:metabolism*; D014508:Urea / Q000378:metabolism; D014527:Uric Acid / Q000378:metabolism
chemical_list: D000596:Amino Acids; D015801:Helminth Proteins; D017672:Nitrogen Compounds; D014527:Uric Acid; D000641:Ammonia; D014508:Urea