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Cell coat formation in Crithidia fasciculata depends on environmental conditions. This surface material is present in hindgut-dwelling parasites but absent in foregut or cultured haptomonads.
Area of Science:
- Parasitology
- Cell Biology
- Insect-Microbe Interactions
Background:
- Haptomonads of Crithidia fasciculata inhabit the Anopheles gambiae mosquito.
- Distinct morphological differences, specifically cell coat presence, are observed between haptomonads from different mosquito gut regions and in culture.
Purpose of the Study:
- To investigate the environmental influence on cell coat formation in Crithidia fasciculata.
- To characterize the composition and potential origin of the cell coat and associated cytoplasmic structures.
Main Methods:
- Comparative morphological analysis of haptomonads from Anopheles gambiae hindgut, foregut, and in vitro culture.
- Cytochemical staining techniques to detect carbohydrates in cell structures.
Main Results:
- A prominent filamentous and granular cell coat is associated with haptomonads in the mosquito hindgut.
- This cell coat is absent in haptomonads from the mosquito foregut and in cultured forms.
- Carbohydrates are present in the cell coat, plasma membrane, and cytoplasmic vesicles, suggesting pinocytosis rather than surface coat formation for these organelles.
Conclusions:
- Cell coat formation in Crithidia fasciculata is environmentally regulated.
- Cytoplasmic vesicles and multivesicular bodies are likely involved in pinocytosis, not surface coat synthesis.
Abstract:
A prominent filamentous and granular cell coat is associated with the plasma membrane of haptomonads of Crithidia fasciculata attached to the cuticular lining of the hindgut of Anopheles gambiae. This surface material is completely absent from morphologically identical haptomonads from the mosquito foregut and from rosettes in culture. On the basis of these observations, it is suggested that cell coat formation is dependent on suitable environmental conditions. A cytochemical staining technique indicates the presence of carbohydrates in (a) the cell coat, (b) the outer leaflet of the plasma membrane of haptomonads from all locations and (c) small cytoplasmic vesicles and multivesicular bodies in all haptomonads. It is suggested that these cytoplasmic organelles represent stages in the intracellular pathway for material ingested by pinocytosis rather than elements involved in surface coat formation.