world of amoeboid organisms

Mayorella with fungus

Mayorella infected by the fungus Amoebophilus simplex

The photomicrograph above shows a Mayorella-species infected by a fungus, probably Amoebophilus simplex. This fungus is specialized in parasitizing mayorellid amoebae, maybe even exclusively Mayorella penardi. Unfortunately, infected amoebae are very rare. I have seen them occasionally and once abundant in a culture.
Infection by a fungus has been occasionally recorded on naked amoebae by several observers. Early researchers erroneously recorded conidia protruding from the posterior end of infected amoeba as uroidal filaments, and a new amoeba genus Ouramoeba Leidy, 1874 was established on this basis. Later, Penard (1902) correctly pointed out that these filaments are of parasitic origin. In spite of Penard’s opinion, Cash and Hopkinson (1905) recorded Leidy’s species Ouramoeba vorax Leidy, 1874 in British fresh water. Further records were identified correctly as fungal infections (Mrva, 2008).

Mayorella with fungus
Globular haustorium
Mayorella with fungus
This amoeba is infected by two fungi; each fungus consists of a chain of some rod-like or cylindrical conidia, rooted in  the hosts cytoplasm by a globular or kidney-shaped haustorium. The arrow indicates a haustorium.
Mayorella with fungus
The same amoeba as above, but now in normal transmitted light.
Mayorella with fungus
This haustorium is attached to the side of a conidium.
Mayorella fungus
Infected Mayorella spec., fungus with a globular haustorium – Voorst
Mayorella fungus Yana Eglit
Infected Mayorella spec., fungus with a globular haustorium – Photomicrograph Yana Eglit
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