Excystation of Eimeria Species: Composition and Removal of the Stieda Body, Activation of Sporozoites, And Alteration in Permeability of the Micropyle

Author

Larry E. Hibbert, Utah State University

Date of Award:

5-1-1969

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Zoology

Committee Chair(s)

Datus M. Hammond

Committee

Datus M. Hammond

Abstract

Freed sporocysts of Eimeria bovis for permanent preparations were smeared on coverslips, fixed, and stained with various stains. The Stieda body had an anterior crescent-shaped cap and a posterior portion; both of these were protein as indicated by their reactions to the mercuricbromphenol-blue, Millon, and ninhydrin-Schiff methods. Freed sporocysts and intact pretreated oocysts of E. bovis and E. auburnensis were observed under a phase-contrast microscope with a warm stage at 39 C for sporozoite activation and Stieda body removal during exposure to 1% taurocholic acid/0.25% trypsin. Sporozoite activation occurred before Stieda body removal; sporozoites started moving, the sporocyst wall became indented at its interface with the Stieda body, a rupture occurred along this indentation, then the Stieda body became detached, and soon underwent disintegration. Non-pretreated oocysts of E. bovis were incubated for 2, 4 , and 6 hr at 39 C in supernatants of oocysts pretreated with 50% CO₂ for 30 hr at 39 C, of ground oocysts which had or had not been so pretreated with CO₂, and of completely excysted intact oocysts; after this incubation, the non-pretreated oocysts were treated with 1% taurocholic acid/0.25% trypsin buffered at pH 7.5 for 9 hr at 39 C. Relatively high levels of excystation were obtained in oocysts of E. bovis and E. auburnensis incubated in supernatants of pretreated oocysts and in distilled water exposed to CO₂. Low levels of excystation were obtained in non-pretreated oocysts that had been incubated in the supernatant of ground oocysts whether or not these had been pretreated with CO₂. Non-pretreated oocysts of E. bovis excysted after incubation in the supernatant of excysted oocysts with or without trypsin inhibitor; heating the supernatant resulted in no excystation. This indicates the presence of a substance which alters the permeability of the micropyle; this substance evidently comes from within the oocysts during excystation, probably as a result of stimulation of CO₂. The micropyles of E. bovis and E. auburnensis oocysts were visibly altered after pretreatment with CO₂. They were permeable to 1% acid fuchsin, and a 0.25% trypsin solution only after such pretreatment. Intact oocysts exposed to trypsin for 5 min, then washed and resuspended in a 1% taurocholic acid solution underwent excystation.

Recommended Citation

Hibbert, Larry E., "Excystation of Eimeria Species: Composition and Removal of the Stieda Body, Activation of Sporozoites, And Alteration in Permeability of the Micropyle" (1969). Biology. 358.
https://digitalcommons.usu.edu/etd_biology/358