Determination of Giardia muris Cyst Viability by Differential Interference Contrast, Phase, or Brightfield Microscopy
- 31 July 1987
- journal article
- research article
- Published by JSTOR in Journal of Parasitology
- Vol. 73 (4), 723-729
- https://doi.org/10.2307/3282401
Abstract
Examination of Giardia muris cysts stained with the fluorogenic dyes, fluorescein diacetate (FDA) or propidium iodide (PI), by either Nomarski differential interference contrast (DIC), phase, or brightfield (BF) microscopy revealed a direct correlation between morphologic appearance and uptake of FDA or PI. Cysts incorporating FDA were all morphologically identical and exhibited (1) a clearly delineated cyst wall, (2) the presence of a distinct space between cyst wall and cytoplasm, and (3) flagella recognizable at one pole of the cyst. FDA-positive cysts also had a hyaline appearance of the cytoplasm (examined at multiple focal planes with DIC) that made it very difficult to detect the presence of nuclei, intracellular axonemes of flagella, or curved elements of the adhesive disc. However, PI-stained cysts possessed a distinct morphology that was clearly different from that of FDA-stained cysts. Examination of PI-stained cysts demonstrated that presence of well-defined nuclei, intracellular axonemes, and curved elements of the adhesive disc. The cytoplasm of PI-stained cysts contained a fine granular texture as opposed to the hyaline appearance of FDA-stained cysts, and no space was observed separating the cyst wall from the underlying cytoplasm in the PI cyst. This light microscopic comparison of viable FDA- and nonviable PI-stained cysts of G. muris demonstrates that 2 types of cysts can be distinguished and implies that structural differences can be used to identify these subpopulations of cysts. The correlation of fluorogenic dye uptake by cysts and their morphologic appearance provide a simple, direct, and inexpensive method for determining the viability of G. muris cysts, which should have wide applicability in studies using environmental factors or chemical agents that may affect Giardia cyst viability.This publication has 6 references indexed in Scilit:
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