Ultrastructure of the marine predatory flagellate <Emphasis Type="Italic">Metromonas simplex</Emphasis> Larsen et Patterson, 1990 (Cercozoa) |
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Authors: | A A Myl’nikova A P Myl’nikov |
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Institution: | (1) Molecular and Microbial Ecology Laboratory, School of Earth and Environmental Sciences, Seoul National University, Seoul, 151-742, Korea;(2) Program in Evolutionary Biology, Department of Biology, Canadian Institute for Advanced Research, Dalhousie University, Halifax, B3H 4J1, Canada; |
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Abstract: | The ultrastructure of the marine predatory flagellate Metromonas simplex Larsen et Patterson was studied. The cell is surrounded by a low-contrast fibrous layer composed of thin hairs covered by
a thin bilayer membrane and an outer layer of thin short fibers. The plasmalemma lies under these layers. The predator captures
whole cells of the prey, usually bodonids or chrysomonads. The cytostome as a cell pocket is undetectable. The long flagellum
bears very thin mastigonemes (hairs) with lengths of 0.8–1.0 μm; the short flagellum is naked and reduced in length. The transitional
zone lacks spirals or other additional elements. The transversal plate is elevated on the cell surface. The flagellar root
system is very simple and has one microtubular band which originates near the kinetosomes. The latter are parallel to each
other and interconnected by fibrous bridges. The vesicular nucleus, Golgi apparatus, and endoplasmic reticulum are of typical
structures. The oval mitochondria of 0.6–2.5 μm contain lamellar cristae. The cylindrical extrusomes (trichocysts) found in
the cytoplasm have lengths of 1.0–1.4 μm and diameters of 0.12–0.08 μm. The trichocysts have a wheel-shaped structure with
13 spokes visible in cross-sections. The contractile vacuole is absent. The similarity that M. simplex shares with Metopion fluens Larsen et Patterson, cryothecomonads, and other predatory flagellates is discussed. |
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