Serum-stimulated feeding in vitro by third-stage infective larvae of the canine hookworm Ancylostoma caninum.
Developmentally arrested nonfeeding infective larvae of hookworms resume development after entry into the host, presumably in response to a signal encountered during invasion. Logically, an initial step in the resumption of development might be the resumption of feeding. An in vitro assay for feeding is described for the third-stage larvae of the canine hookworm Ancylostoma caninum. Populations of larvae incubated under hostlike conditions in the presence of 10% canine serum resume feeding within 6 hr, as evidenced by the uptake of fluorescein-labeled bovine serum albumin. Feeding is dependent on the presence of canine serum, and peaks by 24 hr incubation. Maximal feeding levels occur at temperatures above 34 C with a gas phase of 5% CO2/95% air, whereas culture medium and pH are unimportant for feeding. Serum concentrations between 0.1% and 1.0% (v/v) initiate feeding, and the response peaks at approximately 8.0% serum. Serum triggers feeding within 6 hr and is not required for feeding to continue once initiated. The saturation effect and the trigger phenomenon suggest that the initiation of feeding is a receptor-mediated response.
Hawdon
J M
JM
Department of Pathobiology, University of Pennsylvania, Philadelphia 19104.
Schad
G A
GA
D000722:Ancylostoma / Q000502:physiology*; D000818:Animals; D001769:Blood; D002245:Carbon Dioxide / Q000378:metabolism; D003470:Culture Media; D004285:Dogs; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D013696:Temperature
D003470:Culture Media; D002245:Carbon Dioxide; D010100:Oxygen