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

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.

Characterization of an ecto-5'-nucleotidase (EC 3.1.3.5) activity in intact trophozoites of Trichomonas gallinae

This study describes the enzymatic properties of an ecto-5'-nucleotidase in Trichomonas gallinae. The enzyme hydrolyzes nucleoside monophosphates at pH 7.2 and is activated by divalent cations, such as magnesium. Ecto-5'-nucleotidase activity was insensitive to levamisole, tetramisole (alkaline phosphatase inhibitors), and AMPCP (adenosine 5'-[alpha,beta-methylene]diphosphate), an ecto-5'-nucleotidase inhibitor, whereas 0.1mM ammonium molybdate (considered a potent inhibitor of 5'-nucleotidase activity) completely inhibited the enzyme activity. The apparent K(M) (Michaelis constant) and Vmax (maximum velocity) values for Mg2+-AMP were 466+/-57 microM and 3.7+/-0.59 nmolPi/min/10(6) trichomonads, respectively. Considering that trichomonads lack the ability to synthesize purines and pyrimidines de novo, the presence of an ecto-5'-nucleotidase in intact trophozoites of T. gallinae could be important in regulating the extracellular nucleotide levels and generating adenosine, essential for the survival strategies of the parasite.