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Free-living ciliates as potential reservoirs for eukaryotic parasites: occurrence of a trypanosomatid in the macronucleus of Euplotes encysticus.

Fokin SI, Schrallhammer M, Chiellini C, Verni F, Petroni G - Parasit Vectors (2014)

Bottom Line: Flagellates of the family Trypanosomatidae are obligate endoparasites, which can be found in various hosts.Although the morphological characteristics were not revealing, a high similarity of the trypanosomatids 18S rRNA gene sequence to Herpetomonas ztiplika and Herpetomonas trimorpha (Kinetoplastida, Trypanosomatidae), both parasites of biting midges (Culicoides kibunensis and Culicoides truncorum, respectively) allowed the assignment to this genus.The host-parasite system described here represents a recent example of free-living protists acting as environmental reservoirs for parasitic eukaryotic microorganisms.

View Article: PubMed Central - HTML - PubMed

Affiliation: Microbiology, Institute of Biology II, University of Freiburg, Schänzlestraße 1, Freiburg 79104, Germany. martina.schrallhammer@biologie.uni-freiburg.de.

ABSTRACT

Background: Flagellates of the family Trypanosomatidae are obligate endoparasites, which can be found in various hosts. Several genera infect insects and occur as monoxenous parasites especially in representatives of Diptera and Hemiptera. These trypanosomatid flagellates probably share the worldwide distribution of their hosts, which are often infested by large numbers of endoparasites. Traditionally, their taxonomy was based on morphology, host origin, and life cycle. Here we report the characterization of a trypanosomatid infection detected in a protozoan, a ciliate collected from a polluted freshwater pond in a suburb of New Delhi (India).

Methods: Live observations and morphological studies applying light, fluorescence and transmission electron microscopy were conducted. Molecular analyses of host and parasite were performed and used for phylogenetic reconstructions and species (host) or genus level (parasite) identification.

Results: Although the morphological characteristics were not revealing, a high similarity of the trypanosomatids 18S rRNA gene sequence to Herpetomonas ztiplika and Herpetomonas trimorpha (Kinetoplastida, Trypanosomatidae), both parasites of biting midges (Culicoides kibunensis and Culicoides truncorum, respectively) allowed the assignment to this genus. The majority of the host population displayed a heavy infection that significantly affected the shape of the host macronucleus, which was the main site of parasite localization. In addition, the growth rate of host cultures, identified as Euplotes encysticus according to cell morphology and 18S rRNA gene sequence, was severely impacted by the infection.

Conclusions: The host-parasite system described here represents a recent example of free-living protists acting as environmental reservoirs for parasitic eukaryotic microorganisms.

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Related in: MedlinePlus

15–19. Ultrastructure of trypanosomatid flagellate Herpetomonas sp. Ind3 infecting Euplotes encysticus. 15–18. Flagellates harbored in the host cytoplasm. 15, 18. Longitudinal sections of flagellates. 16. Cross-sectioned flagellate through the flagellar pocket; the flagellum, which already bears a paraflagellar rod, is visible. Regularly distributed subpellicular microtubules are also well visible (diagonal arrow). 17. Cross section of two flagellate cells after fission. 19. Parasites in the macronucleus of the host. N, nucleus; horizontal arrow, kinetoplast; double arrows, flagellum. Bars = 1 μm.
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Figure 4: 15–19. Ultrastructure of trypanosomatid flagellate Herpetomonas sp. Ind3 infecting Euplotes encysticus. 15–18. Flagellates harbored in the host cytoplasm. 15, 18. Longitudinal sections of flagellates. 16. Cross-sectioned flagellate through the flagellar pocket; the flagellum, which already bears a paraflagellar rod, is visible. Regularly distributed subpellicular microtubules are also well visible (diagonal arrow). 17. Cross section of two flagellate cells after fission. 19. Parasites in the macronucleus of the host. N, nucleus; horizontal arrow, kinetoplast; double arrows, flagellum. Bars = 1 μm.

Mentions: Inside the host organelle, the flagellates were immotile. After rupture of the macronucleus several parasites started to move vigorously in the culture medium. In a few host cells, low numbers (up to 10–15) of parasites were recorded in cytoplasmatic vacuoles (Figure 4. 15-18), some of those were observed after recently completed cell division (Figure 4. 17).


Free-living ciliates as potential reservoirs for eukaryotic parasites: occurrence of a trypanosomatid in the macronucleus of Euplotes encysticus.

Fokin SI, Schrallhammer M, Chiellini C, Verni F, Petroni G - Parasit Vectors (2014)

15–19. Ultrastructure of trypanosomatid flagellate Herpetomonas sp. Ind3 infecting Euplotes encysticus. 15–18. Flagellates harbored in the host cytoplasm. 15, 18. Longitudinal sections of flagellates. 16. Cross-sectioned flagellate through the flagellar pocket; the flagellum, which already bears a paraflagellar rod, is visible. Regularly distributed subpellicular microtubules are also well visible (diagonal arrow). 17. Cross section of two flagellate cells after fission. 19. Parasites in the macronucleus of the host. N, nucleus; horizontal arrow, kinetoplast; double arrows, flagellum. Bars = 1 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4022238&req=5

Figure 4: 15–19. Ultrastructure of trypanosomatid flagellate Herpetomonas sp. Ind3 infecting Euplotes encysticus. 15–18. Flagellates harbored in the host cytoplasm. 15, 18. Longitudinal sections of flagellates. 16. Cross-sectioned flagellate through the flagellar pocket; the flagellum, which already bears a paraflagellar rod, is visible. Regularly distributed subpellicular microtubules are also well visible (diagonal arrow). 17. Cross section of two flagellate cells after fission. 19. Parasites in the macronucleus of the host. N, nucleus; horizontal arrow, kinetoplast; double arrows, flagellum. Bars = 1 μm.
Mentions: Inside the host organelle, the flagellates were immotile. After rupture of the macronucleus several parasites started to move vigorously in the culture medium. In a few host cells, low numbers (up to 10–15) of parasites were recorded in cytoplasmatic vacuoles (Figure 4. 15-18), some of those were observed after recently completed cell division (Figure 4. 17).

Bottom Line: Flagellates of the family Trypanosomatidae are obligate endoparasites, which can be found in various hosts.Although the morphological characteristics were not revealing, a high similarity of the trypanosomatids 18S rRNA gene sequence to Herpetomonas ztiplika and Herpetomonas trimorpha (Kinetoplastida, Trypanosomatidae), both parasites of biting midges (Culicoides kibunensis and Culicoides truncorum, respectively) allowed the assignment to this genus.The host-parasite system described here represents a recent example of free-living protists acting as environmental reservoirs for parasitic eukaryotic microorganisms.

View Article: PubMed Central - HTML - PubMed

Affiliation: Microbiology, Institute of Biology II, University of Freiburg, Schänzlestraße 1, Freiburg 79104, Germany. martina.schrallhammer@biologie.uni-freiburg.de.

ABSTRACT

Background: Flagellates of the family Trypanosomatidae are obligate endoparasites, which can be found in various hosts. Several genera infect insects and occur as monoxenous parasites especially in representatives of Diptera and Hemiptera. These trypanosomatid flagellates probably share the worldwide distribution of their hosts, which are often infested by large numbers of endoparasites. Traditionally, their taxonomy was based on morphology, host origin, and life cycle. Here we report the characterization of a trypanosomatid infection detected in a protozoan, a ciliate collected from a polluted freshwater pond in a suburb of New Delhi (India).

Methods: Live observations and morphological studies applying light, fluorescence and transmission electron microscopy were conducted. Molecular analyses of host and parasite were performed and used for phylogenetic reconstructions and species (host) or genus level (parasite) identification.

Results: Although the morphological characteristics were not revealing, a high similarity of the trypanosomatids 18S rRNA gene sequence to Herpetomonas ztiplika and Herpetomonas trimorpha (Kinetoplastida, Trypanosomatidae), both parasites of biting midges (Culicoides kibunensis and Culicoides truncorum, respectively) allowed the assignment to this genus. The majority of the host population displayed a heavy infection that significantly affected the shape of the host macronucleus, which was the main site of parasite localization. In addition, the growth rate of host cultures, identified as Euplotes encysticus according to cell morphology and 18S rRNA gene sequence, was severely impacted by the infection.

Conclusions: The host-parasite system described here represents a recent example of free-living protists acting as environmental reservoirs for parasitic eukaryotic microorganisms.

Show MeSH
Related in: MedlinePlus