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of basal portion and cone- shaped apex (Fig. 10.2). However, the cell body can reside on a stalk of considerable length, up to 600 µm in some Oxychonina species, while the neck can be extended and quite elongated in some Filichona species (Jankowski, 1973b). Suctorians , like chonotrichs , can be attached directly to the substrate or elevated off it on a stalk (Figs. 10.4\u2013 10.6). In those species attached to the substrate, body form can be quite variable. Batisse (1994b) recognized five major morphological types (i.e., monaxon \u2013 Podophrya ; homaxon \u2013 Sphaerophrya ; radial \u2013 Cyclophrya ; bilateral \u2013 Stylophryodendron ; and irregular \u2013 Lernaeophrya , Dendrosoma ), but acknowledged it was not easy to classify a form unambiguously. This will be complicated further by any phenotypic plasticity exhibited by a species. The basic pattern for the somatic ciliature of the class is considered to be that of a free-living cyr- tophorian , such as Chilodonella or Chlamydodon 10.3 Somatic Structures 221 Fig. 10.6. Stylized drawings of representatives of the Subclass Suctoria of the Class PHYLLOPHARYNGEA . The endogenid Tokophrya and its bud . Note the so-called \u201c divergent kinety \u201d in the \u201cposterior\u201d half of the cell, which may be the homologue of the external right kinety of cyrtophorians 222 10. Subphylum 2. INTRAMACRONUCLEATA: Class 4. PHYLLOPHARYNGEA (Fig. 10.1). The somatic ciliature, which is highly thigmotactic, is ventral and divided into a right field and a left field. Typically, the right field is more developed than the left field, arching ante- riorly in front of the oral region over onto the left ventral surface (Fig. 10.1). On the right edge of the right field are the remnants of a kinety, called the external right kinety ; one kinetofragment is located at the cell equator and the other is often located on the dorsal left surface. (Deroux, 1970, 1976a, 1976b, 1977; Deroux & Dragesco, 1968). These external right kineties , and the overall pattern of the ciliature, are also present in hypocomatid rhyn- chodians , demonstrating their probable common ancestry with the cyrtophorians (Deroux, 1975). This general pattern of ciliature is also found in the buds of chonotrichs (Dobrza ska-Kaczanowska, 1963; Fahrni, 1984; Guilcher, 1951), suggesting an ontogenetic recapitulation of their common ancestry (cf. Figs. 10.1, 10.2). Finally, the somatic ciliature of the suctorian swarmer is believed to represent the right ventral ciliature of its cyrtopho- rian (?) ancestor, the left field having been lost. The remaining right field then extends in a horse-shoe around the anterior end in some species while the whole ciliature has \u201cslipped\u201d to an equato- rial position in other species, forming a girdle of ciliature (Figs. 10.3\u201310.6). Foissner and Foissner (1995) demonstrated by ultrastructural study that the \u201cpolarity\u201d of these girdle kineties is trans- verse rather than anterior-posterior in orientation. Suctorian swarmers swim with the tentacles in the \u201crear\u201d and the scopuloid , used for attachment going first! Are they swimming backwards or forwards? A glycocalyx covers the plasma membrane of phyllopharyngeans , reaching its full develop- ment in sessile forms (Fahrni, 1982; Henk, 1979; Sundermann & Paulin, 1985). This layer, which may function in prey capture, is very susceptible to fixation treatment and can be best demonstrated by either freeze-etching or ruthenium red staining, demonstrating its polysaccharide nature (Henk; Sundermann & Paulin). Underlying the plasma membrane is an alveolar layer that is typically con- spicuous in members of this class, sometimes the alveoli contain material (Grain & Batisse, 1974; Lom & Kozloff, 1968). The epiplasm is a consist- ent feature of the phyllopharyngean pellicle, vary- ing in thickness depending upon the region of the body. In some cyrtophorians , it can be somewhat thicker on the dorsal, non-ciliated surface, which is also underlain by triads of microtubules (Kurth & Bardele, 2001). The dorsal surface of rhynchodi- ans can be underlain by many layers of micro- tubules (Lom & Kozloff, 1970). The epiplasm can be more than 1 µm thick in some chonotrichs (Fahrni, 1982; Karadzhan, 1976) and suctorians (Grell & Benwitz, 1984; Grell & Meister, 1982b). Pores penetrate through the non-ciliated pellicle of chonotrichs and suctorians , and there may be over 100,000 on an average Spirochona (Fahrni, 1982). These pores are sites of active pinocytosis in suc- torians , providing the ciliate with macromolecules from the medium (Rudzinska, 1980). It was the structure of the somatic kinetid that convinced Small and Lynn (1981) to unite these four major groups into the Class PHYLLOPHARYNGEA , based on the descrip- tions of several pioneering studies (e.g., Batisse, 1973; Grain & Batisse, 1974; Lom & Corliss, 1971; Lom & Kozloff, 1970; So\u142ty ska, 1971). The characterization of the kinetid by Lynn (1981, 1991) is supported by recent descriptions (Foissner & Foissner, 1995; Kurth & Bardele, 2001). The phyllopharyngean monokinetid is as follows: a slightly convergent postciliary ribbon at triplet 9, a short, rapidly tapering and laterally directed kine- todesmal fibril at triplets 5 and 6, and a transverse fibre at triplet 3 (Fig. 10.7). Transverse micro- tubules may be associated with triplet 4 in some taxa (e.g., Chlamydodon \u2013 Kurth & Bardele, 2001; Spirochona \u2013 Fahrni, 1982; Hypocoma \u2013 Grell & Meister, 1983) (Fig. 10.7). The postciliary micro- tubules typically extend to overlap each other in a \u201ctriad\u201d arrangement, accompanying other ribbons in the right cortical ridge, while the transverse microtubules, when present, extend slightly poste- riorly and laterally to support the left cortical ridge (Fig. 10.8). Parasomal sacs typically occur on the right side of the kinetosome, but may also occur on the left (Fig. 10.7) (see Lynn, 1991). Finally, subkinetal microtubules originate as a flat ribbon from the base of the kinetosome and extend anteri- orly beneath those originating from more anterior kinetosomes (Kurth & Bardele, 2001; Lynn, 1991). Their orientation in some suctorians cannot be concluded with precision given the unusual orien- tations of their somatic kineties. Small mucocysts are distributed throughout the ciliated cortex of cyrtophorians (Kurth & Bardele, 2001) and rhynchodians (Lom & Kozloff, 1970). Some dysteriid cyrtophorians have well-developed podites that are used for attachment to substrates (Deroux, 1975; Fauré-Fremiet, André, & Ganier, 1968a). Other cyrtophorians and hypocomatids have a posterior \u201cattachment\u201d region, a portion of the somatic cortex with some associated kineties with densely spaced kinetosomes and a secretory pellicular area (Deroux, 1975). Abundant secre- tory vesicles , likely containing a mucoprotein, are found in the holdfast organelle of cyrtophorians (Lom & Corliss, 1971; Fauré-Fremiet et al., 1968a) and chonotrichs (Fahrni, 1984) where they provide substances for the temporary attachment structures and for the basal disc and stalk , respectively. The scopuloid is likely the homologous structure in the suctorians . Secretions from vesicles in the scopuloid provide material for the basal disc, non-contractile stalk , and, in some species, the lorica . A thin dense outer layer surrounds a stalk matrix, which is highly variable in appearance: it can be composed of fibres that are periodically striated (e.g., Acineta \u2013 Batisse, 1967a; Acinetopsis \u2013 Grell & Meister, 1982b; Thecacineta \u2013 Batisse, 1969) or mostly not (e.g., Tokophrya \u2013 Batisse, 1970). The stalk is a highly resistant structure com- posed of proteins and sulfate groups, possibly also polysaccharides , and it can represent up to 15% of the total protein of the cell (Hascall, 1973). In loricate forms,