Morphological aspects of Monocercomonas sp. and investigation on probable pseudocysts occurrence

Abstract

Monocercomonas sp. is a flagellate protozoan found in the large intestine of snakes and in insects. Light microscopy revealed the measurements of morphological features of the trophozoites. Scanning electron microscopy showed in detail the emergence of the three anterior flagella, the recurrent flagellum, the axostyle, and the absence of undulating membrane. In addition, we described spherical forms which are probably pseudocysts. The investigation on the occurrence of this process was carried out through the incubation of Monocercomonas sp. trophozoites in several stressful conditions, such as pH change, nutrient depletion and different temperatures. Results revealed high pseudocyst formation at acidic pH values (4.0, 5.0, and 6.0), in absence of serum and in incubation at 37 degrees C. The occurrence of these pseudocystic forms in trichomonads life cycle is under investigation. This study describes the external structure of Monocercomonas sp., as demonstrated by light and scanning electron microscopy. Moreover, to our knowledge, this is the first time that formation of probable pseudocysts is shown in Monocercomonas sp., contributing to the research field on termite protozoa biology.

Long-term in vitro cultivation of Histomonas meleagridis coincides with the dominance of a very distinct phenotype of the parasite exhibiting increased tenacity and improved cell yields

“…In related parasites such as Monocercomonas sp. or T. foetus , changes in incubation temperature can be used to induce pseudo-cyst formation (Granger et al 2000; Borges et al 2007). Hence, it could be assumed that lowering the temperature to 4 °C in the culture medium also triggered a sort of survival mechanism in H. meleagridis .…”

The ambiguous life ofDientamoeba fragilis: the need to investigate current hypotheses on transmission

“…In cultures of Monocercomonas, the largest number of pseudocyts were produced when cultures were incubated for 4-5 days at pH levels between 5 and 6 (Borges et al 2007). In cultures of Monocercomonas, the largest number of pseudocyts were produced when cultures were incubated for 4-5 days at pH levels between 5 and 6 (Borges et al 2007).…”

“…Furthermore, another feature of pseudocysts in trichomonads is that they are multinucleated (Pereira-Neves et al 2003;Borges et al 2007). Pseudocyst formation as observed in some trichomonads is easily noted by the invagination of the flagella.…”

Dientamoeba fragilis, the Neglected Trichomonad of the Human Bowel

“…Literature on trichomonads such as Tritrichomonas foetus and free-living Monocercomonas species (166)(167)(168), all of which are parabasalids that share an ancestor with D. fragilis (169), shows that these species produce pseudocysts under unfavorable environmental conditions. Pseudocysts are nonmotile, multinucleated, typically spherical forms without a true cyst wall.…”