The food resource of adult Heligmosomoides polygyrus in the small intestine

The aim of this study was to identify the food resources of Heligmosomoides polygyrus, a gastrointestinal nematode of mice. Gastrointestinal nematodes obtain food from 1 of 3 compartments: host ingesta, blood, or intestinal tissue. A method was developed to label these compartments differentially in the living host using 2 fluorescent marker dyes and to record in situ feeding activity of the parasite. Fluoresbrite is a yellow-green fluorescent dye bound to small-diameter beads that are membrane impermeable. Thus, it is restricted to the bloodstream when introduced there, or it remains in the ingesta when fed to the host. Rhodamine B, a red fluorescent dye, is membrane permeable and stains tissue cytoplasm. These dyes were fed to or injected into the bloodstream of the host. Following treatment, the worms were removed, and the contents of the worm intestines were examined by fluorescent microscopy. Worm intestinal contents only fluoresced with rhodamine B dye. These results suggest that H. polygyrus adults feed on tissue in the living host and not on host ingesta or blood.