Ultrastructure of the amoebo-flagellate Protonaegleria westphali

Abstract

Investigation of the ultrastructure of Protonaegleria westphali has been carried out by means of scanning electron microscopy (SEM) and transmission electronmicroscopy (TEM). SEM investigation demonstrated much enlarged trophozoites, flagellates and cysts corresponding to those under light microscopical observation. In situ fixation of moving trophozoites revealed attachment to the substratum by many uroidal and lateral filopodia. The typical flagellate stage has four flagella inserted two by two at the anterior pole of the cell. The smooth wall of cysts had prominent pores sealed by a mucous plug. Apart from their greater size, trophozoites and cysts resemble those of the genus Naegleria. Mitochondria are not as elongated as in the case of Naegleria; rather, they are round. The cyst is surrounded by a thick, layered endocyst (0.2-0.5 micron) and a delicate ecotcyst loosely apposed to the endocyst. Both walls join at the region of the prominent pores, forming a characteristically thick collar. This, together with the pore structure (up to 1.0 micron in diameter) places the amoeba in group I of N. gruberi, according to Pussard and Pons (1979). The flagellate state usually has four flagella which are anchored firmly by a prominent flagellar apparatus or mastigont at the anterior pole of the cell, comparable to that of the genus Tetramitus. The flagella show a typical 9 + 2 arrangement of microtubules (MT) and are surrounded by a sheath which is continuous with the cell membrane. Main elements of the mastigont could be demonstrated as typical kinetosomes of 0.75 micron length. Each is closely associated with the cross-striated rhizoplast located perpendicular to it.(ABSTRACT TRUNCATED AT 250 WORDS)

Dactylomonas gen. nov., a Novel Lineage of Heterolobosean Flagellates with Unique Ultrastructure, Closely Related to the Amoeba Selenaion koniopes Park, De Jonckheere & Simpson, 2012

“…The flagellates that lack the feeding groove (species of Naegleria , Willaertia , and Euplaesiobystra ) are mostly ephemeral (Michel et al. ; Park et al. ; Patterson et al.…”

“…Within Hererolobosea, a microtubular corset was reported only from Willaertia and Pleurostomum (Michel et al. ; Park et al. ).…”

“…Heterolobosean flagellates typically feed on bacteria, using a well-developed feeding groove or cytostome (Brugerolle and Simpson 2004;Park and Simpson 2011;Park et al 2007). The flagellates that lack the feeding groove (species of Naegleria, Willaertia, and Euplaesiobystra) are mostly ephemeral (Michel et al 1987;Park et al 2009;Patterson et al 1981), except for the highly derived Creneis (P anek et al 2014a). In Dactylomonas, we have not identified any feeding structure or observed the process of phagocytosis.…”

“…The cells are spindle-shaped and possess a complete microtubular corset, which could prevent phagocytosis. Within Hererolobosea, a microtubular corset was reported only from Willaertia and Pleurostomum (Michel et al 1987;Park et al 2007). In addition, a microtubular corset is possibly present also in Pharyngomonas (see Fig.…”

Characterization of Selenaion koniopes n. gen., n. sp., an Amoeba that Represents a New Major Lineage within Heterolobosea, Isolated from the Wieliczka Salt Mine

“…Nonetheless some unusual features were observed. The fact that the cyst pores seem to penetrate only through the endocyst is a significant difference from operculate taxa that have been studied by electron microscopy, such as Naegleria, Willaertia, Pernina, Tulamoeba, and Monopylocystis (Kadiri et al 1992;Michel et al 1987;O'Kelly et al 2003;Park et al 2009;Schuster 1975). The overall dense nature of the plug contrasts with the plugs in Naegleria, Willaertia, and Pernina, which are diffuse, except, usually, for a relatively narrow basal plate of high density (Cha´vez-Munguı´a et al 2009;Kadiri et al 1992;Michel et al 1987;Schuster 1975;Visvesvara et al 2005).…”