Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 14, 1998
Publication Date: N/A
Interpretive Summary: The stomach worm, Haemonchus contortus is an economically important parasite of grazing animals. The adult parasite is blood-feeding and often causes death on the host. The current experiment is part of ongoing studies of the basic adaptation of the parasite to the host and the use of this knowledge to design new controls. A globin-like protein that is different from host hemoglobin was purified and characterized from H. contortus adults. This globin is synthesized by the adult parasite and is present in the fourth larval stage but is absent in earlier developmental stages. The globin may not serve primarily as an oxygen transport molecule but may serve as an oxygen storage protein, as an iron reservoir. The results suggest that H. contortus globin is similar to globins from other nematode parasites but different from those of the mammalian host. Interference with synthesis or function of globin in nematodes may be an attractive target for development of novel controls.
A protein with characteristics of globin was purified from supernatants of Haemonchus contortus extracts by high pressure liquid chromatography. The purified protein had a Mr of 33 kDa under nondenaturing conditions and a Mr of 19 kDa by reducing SDS-PAGE suggesting the globin may exist as a dimer. Three peptides resulting from proteolytic digest of the purified globin were sequenced and had strong homology to other nematode globins particularly to that from Trichostrongylus colubriformis. The L3-stage lacked globin but the L4-stage contained a globin with Mr of 19.6 kDa. Adult H. contortus incubated overnight in 3H-leucine, incorporated radioactivity into a peak that coeluted with globin indicating the adults synthesize globin in vitro.