The Ultrastructure of Chaenea teres and an Analysis of the Phylogeny of the Haptorid Ciliates

Chaenea teres has typical haptorid ultrastructure. The somatic monokinetid has two transverse microtubular ribbons, an overlapping postciliary microtubular ribbon, and a laterally directed kinetodesmal fiber. The evered cytopharynx forms a dome at the apical end of the cell. The base of the dome is surrounded by oral dikinetids. The left, anterior kinetosome of the oral pair is not ciliated and has a transverse microtubular ribbon, a nematodesmata and a single postciliary microtubule. The right, posterior kinetosome is ciliated and has only postciliary microtubules. The kinetosomes at the anterior ends of the somatic kinetics are close together and their transverse microtubules and nematodesmata contribute to the support of the cytopharynx. The transverse microtubules of these oralized somatic kinetosomes, together with those from the oral dikinetids, line the cytopharynx. Accessory or bulge microtubules arise perpendicular to the transverse microtubules. A dorsal brush of three kineties of clavate cilia is found on the cell surface just posterior to the oral region. Mucocysts and a single type of toxicyst are present. The toxicysts are confined to the oral region. There are multiple ovoid macronuclei that stain weakly. Micronuclei were not observed. Cladistic analysis indicates the Chaenea may be most closely related to Fuscheria and Acropisthium. The cladistic analysis also suggests that existing taxonomies of the subclass Haptoria need to be revised. We propose some modifications to Foissner & Foissner's classification that include transferring Helicoprorodon, Actinobolina, the buetschiliids, and the balantidiids to the order Haptorida and recognizing the close relationship between pleurostomes and spathidiids.     

Somatic Infraciliature in the Haptorid Ciliate Homalozoon vermiculare (Kinetophragminophora, Gymnostomata) Ditransversalia N. Subcl. and Phylogenetic Implications

The ultrastructure of the cortex of Homalozoon vermiculare is described. The ventral side bears 13–15 iongitudinal kineties composed of monokinetids. On the dorsal surface, there are 3 kineties, 2 of which are composed of dikinetids in the anteriormost part of the cell. Consequently there exist 3 different kinds of kinetids within the somatic cortex: 1) The monokinetids on the ventral side are associated with a kinctodesmal fibril, 2 transverse microtubular ribbons and 7 postciliary microtubules in a double-row configuration; 2) The monokinetids on the dorsal side are very similar but they are associated with just 3 very 'short postciliary microtubules; 3) The posterior kinetosome of the dorsal dikinetids bears the same fibrillar associates as the dorsal monokinetid, but it lacks the second transverse ribbon. The anterior kinetosome of each pair is associated with a single postciliary' microtubule. The kinetid organization of Homalozoon is compared to that of other members of the Haptorida. Their phylogeny is discussed. A monophyleiic taxon within the litostomate ciliates is characterized by data on the somatic kinetids, and the new subclass Ditransversalia n. subcl. is constituted. The new subclass comprises the genera Balantidium, Bryophyllum, Enchelydium, Homalozoon, Isotricha, Lacrymaria, Lepidolrachelophyllum, Spathidium and Vestibulongum .     

Morphology and Ecology of Siroloxophyllum utriculariae (Penard, 1922) N. G., N. Comb. (Ciliophora, Pleurostomatida) and an Improved Classification of Pleurostomatid Ciliates

ABSTRACT. The morphology and infraciliature of Siroloxophyllum utriculariae (Penard, 1922) n. g., n. comb. were studied in live cells, with the scanning and transmission electron microscope, as well as in specimens impregnated with protargol and silver carbonate. The new genus, Siroloxophyllum , belongs to the Loxophyllidae and has a specific combination of characters, viz. an oral bulge surrounding almost the entire cell, three perioral kineties, a single brush kinety, and a single right dorsolateral kinety. The ecology and faunistics of S. utriculariae are reviewed. It is a rare and infrequent predator preferring clean freshwaters. The somatic monokinetid of S. utriculariae has typical haptorid ultrastructure, including two transverse microtubular ribbons. The oral bulge is patterned string-like with riffles containing the transverse microtubular ribbons originating from the oral kinetids. Perioral kineties 1 and 2 consist of dikinetids having one basal body each ciliated; the nonciliated basal body is associated with a nematodesmal and a transverse microtubular ribbon. Perioral kinety 3 consists of ciliated monokinetids having a fine structure similar to the somatic kinetids; they form triads with the dikinetids from perioral kinety 2. The classification of pleurostomatid ciliates is reviewed. Two suborders (Amphileptina, Litonotina) and three families (Amphileptidae, Litonotidae, Loxophyllidae n. fam.) are recognized and defined.     

THE ORGANIZATION AND EVOLUTION OF MICROTUBULAR ORGANELLES IN CILIATED PROTOZOA

(1) Ciliated protozoa are viewed as unicellular organisms structured in a hierarchy of organizational levels that include the macromolecular, suborganellar, unit organellar, organellar complex, and organellar system. (2) The ciliate cortex is divided into two major functional regions, the somatic region and the oral region. The fundamental component of the cortex is an organellar complex, the kinetid, whose organizing centre is the kinetosome with which are associated three fibrillar associates diagnostic of ciliates. These three fibrillar associates are the periodically striated kinetodesmal fibril and two microtubular ribbons, the transverse and postciliary ribbons. (3) Somatic and oral kinetids are found to be of three major types: monokinetids are composed of one kinetosome and its fibrillar associates; dikinetids are composed of two kinetosomes and their fibrillar associates; polykinetids are composed of more than two kinetosomes and their fibrillar associptes. (4) The mechanisms underlying kinetid function and development remain largely unexplored. Research into the molecular biology and ultrastructure, especially of mutant forms, should provide basic insights in the near future. (5) The conservation of kinetid structure across major phyla of organisms suggests that this subcellular structure should be useful in phylogenetic analysis despite the concepts of ‘chemical identity’ and ‘organic design’. (6) The evolutionary rate of change of oral features is greater than that of somatic features, probably due to developmental and ecological factors. Nevertheless both cortical regions are constrained by the phenomenon of structural conservatism; that is, the conservation of structure through time is inversely related to the level of biological organization. (7) Eight major groupings of ciliate species are recognized, based on ultrastruc-tural features of the cortex. Several examples of differences between these eight groups and the groups presently recognized are discussed.     

The Cytology of Sheep Rumen Ciliates. III. Ultrastructure of the Genus Entodinium (Stein)1

This study examines previously undescribed general and cytopharyngeal features of the genus Entodinium. The cytopharynx contains three types of microtubular ribbons underlying the cytostomal membrane as well as a loose palisade of nematodesmata. A protoesophagus composed of microtubular bundles associated with a fibrous wall lies internally to one side of an extrusible peristome on which the adoral zone of syncilia (AZS) is mounted. Macronuclear structures are very similar to those of other ophryoscolecids. The micronucleus has chromatin bodies forming a compact mass but lacks the thick wall found in other species. A tubular spongiome surrounds the contractile vacuole and the cytoproct is relatively undifferentiated. Cortical structure follows the usual five-layered ophryoscolecid pattern with subcortical barren kinetosomes arranged into indistinct kineties. The infraciliature of the AZS has kinetosomes set upon a subkinetal rod and with associated bifurcated kinetodesmata and transverse microtubules, some of which extend into the cytopharynx. Components newly described for Entodinium are the one to three postciliary microtubules and the interkinetosomal centro-lateral strand, all of which are present in other species of ophryoscolecid ciliates. The infraciliature of the paralabial ciliary tuft shows similar components to that of the main AZS, but lacks the subkinetal rod. The microtubular components of the cytopharynx are discussed in relation to the “alimentary” structures in other ophryoscolecids, and a relationship of these structures to dietary differences is suggested.     

The Cytology of Sheep Rumen Ciliates. II. Ultrastructure of Eudiplodinium maggii1

The anterior adoral zone of syncilia (AZS) of Eudiplodinium maggii is mounted on an extrusible peristome within a vestibulum. The peristome contains cytopharyngeal components derived from the infraciliature. These components include a crescent-shaped palisade of nematodesmata, two types of sub-membrane cytopharyngeal ribbons, and an ensheathing fibrous layer enclosing a phagoplasmic zone containing the other components. A convoluted esophagus is continuous with and extends from the posterior of the cytopharynx adjacent to the macronucleus. A posterior cytoproct has specialized cytoplasm around it and associated myoneme-like elements. The skeletal plate is composed of finely granular platelets and lies under the cortex ventral to the macronucleus. The endoplasm is separated from the ectoplasm by a fibrous boundary layer. The cortex has an external glycocalyx, a membranous layer, epiplasm, and microtubular and microfilament layers. The AZS infraciliature is of the usual cntodiniomorph type, kinetosomes linked by a sub-kinetosomal rod and with associated bifurcated kinetodesma, postciliary and transverse microtubules-the latter extending into the cytopharynx—nematodesmata, and a fibrous reticulum. A possible vestigial, somatic infraciliature consisting of short, barren kinetosomes with associated basal and cortex-directed microtubules and a periodic incomplete fiber, is found subcortically throughout the cell.     

The Ultrastructure of Zosterodasys agamalievi (Ciliophora: Synhymeniida)

ABSTRACT. The cell surface of the synhymeniid ciliate, Zosterodasys agamalievi , consists of shallow kinetal grooves separated by low cortical ridges. Numerous electron-opaque bodies are located in the cortical ridges, inside the kinetal grooves, and are distributed in parallel rows between adjacent kineties. Well-developed alveoli are present beneath the cell surface membrane. Zosterodasys agamalievi has a single micronucleus and a homomerous macronucleus. The infraciliature of the somatic monokinetid consists of an anteriorly-directed kinetodesmal fiber, a well-developed divergent postciliary microtubular ribbon, radially-oriented transverse microtubules, and a short striated rootlet, which extends anteriorly from the base of the kinetosome into the cell. Zosterodasys agamalievi has a perioral band of paired cilia, the synhymenium, that winds obliquely across the ventral surface of the body, just posterior to the cytostome. The infraciliature of the anterior kinetosome of the synhymenium consists of two postciliary microtubules; a well-developed, divergent post-ciliary ribbon of microtubules and a short kinetodesmal fiber are associated with the posterior kinetosome. The cytopharynx is supported by 14-16 nematodesmata which are capped distally by a capitulum. The cytopharynx is bound proximally by a fibrous sheath and is lined by radially-arranged microtubular ribbons. No obvious oral ciliature is present.     

The Cytology of Sheep Rumen Ciliates. I. Ultrastructure of Epidinium caudatum Crawley1

Epidinium caudatum has an anterior vestibulum containing the adoral zone syncilia (AZS) on an extrusible peristome. The cytopharyngeal structures include a funnel-shaped arrangement of nematodesmata, longitudinal and transversely oriented microtubular ribbons all of which are located in the peristome, a structure which also contains filamentous phagoplasm. The origins of the microtubular ribbons indicate affinities to the rhabdos type of cytopharynx. The peristomal base is continuous with the tubular esophagus, the region connecting the two being ensheathed by a fibrous layer and low density cytoplasm. The esophagus has a microtubular/microfilamentous wall. A distinct cytoproct with associated myonemal structures occurs posteriorly. The skeletal plates consist of a large number of interconnected, variably shaped platelets and may have dual skeletal and storage functions. The endoplasm is more vesicular than the ectoplasm, the two separated by a fibrous boundary layer. The five-layered cortex has an external glycocalyx, a plasma membrane with two subtending membranes, homogeneous, microtubular, and microfilamentous layers. The syncilia of the AZS are mounted in a U-shaped band on the peristome with transversely oriented kinetics consisting of kinetosomes linked by a sub-kinetosomal rod. There is a bifurcated kinetodesma, dense support material forming a lateral spur with associated transverse microtubules, and postciliary, interkinetal, and occasional basal microtubules, nematodesmata, and a subciliary reticulum. A barren, possibly vestigial, somatic infraciliature consists of non-ciliated kinetosomes and a basal striated fiber with associated basal and perpendicular (cortical) microtubules.     

Ultrastructure of the Somatic Cortex of the Gymnostome Ciliate Spathidium spathula (O. F. M.)1

The somatic cortex of Spathidium spathula is described ultrastructurally. The pellicle consists of an outer membrane and an underlying alveolar system. Numerous membrane-bound mucocysts and spherical electron-opaque bodies have similar circular sites of attachment to the outer membrane. Below these are a microfibrillar zone and an underlying region of rough ER. Mitochondria are lined up under the rough ER in longitudinal cortical ridges. Parasomal sacs are found near the basal bodies and are associated with cytoplasmic membranous sacs. Various microtubular and fiber systems are associated with single basal bodies: (1) a short kinetodesmal fiber; (2) two transverse microtubular ribbons and a transverse fiber; (3) a postciliary microtubular ribbon, initially sandwiched by two fibers, which gives rise to longitudinal subpellicular microtubules extending posteriorly for a distance of some four or five basal bodies; and (4) a system of overlapping subkinetal microtubules. A three-dimensional reconstruction is included. The somatic cortex of S spathula is similar to that reported for other Haptorida of the ciliate subclass Gymnostomata.     

Ultrastructure of the Oral Apparatus of Mesodinium rubrum from Korea

Mesodinium rubrum Lohmann is a photosynthetic marine ciliate that has functional chloroplasts of cryptophyte origin. Little is known about the oral ultrastructure of M. rubrum compared with several reports on the sequestration of nuclei and plastids from prey organisms, such as Geminigera cryophila and Teleaulax species. Here, we describe the fine structure of the oral apparatus of a M. rubrum strain from Gomso Bay, Korea. The cytopharynx was cone‐shaped and supported by 20–22 ribbons of triplet microtubules. At the anterior end of the cytopharynx, an annulus anchored small cylinders composed of 11 microtubules. The small cylinders were spaced at regular intervals, each reinforced by one set of the triplet microtubules. At the opening of the cytostome, larger 14‐membered microtubular cylinders were set adjacent to the small, 11‐membered microtubular cylinders, each pair surrounded by separate membranes, however, only the large cylinders extended into the oral tentacles. There were 20–22 oral tentacles each having one to five extrusomes at its tip. At the anterior end of the oral apparatus, microtubular bands supporting the cytostome curved posteriad, extending beneath the cell cortex to the kinetosomes of the somatic cirri. The microtubular bands were connected by striated fibers and originated from kinetosomes anchored by fibers. Each cirrus consisted of eight cilia associated with 16 kinetosomes. The ultrastructure of M. rubrum from Korea provides information useful for taxonomic characterization of the genus Mesodinium and relevant to developing a better understanding of the acquisition of foreign organelles through phagocytosis by M. rubrum.     

FOOD VACUOLE MEMBRANE GROWTH WITH MICROTUBULE-ASSOCIATED MEMBRANE TRANSPORT IN PARAMECIUM

Evidence from a morphological study of the oral apparatus of Paramecium caudatum using electron microscope techniques have shown the existence of an elaborate structural system which is apparently designed to recycle digestive-vacuole membrane. Disk-shaped vesicles are filtered out of the cytoplasm by a group of microtubular ribbons. The vesicles, after being transported to the cytostome-cytopharynx region in association with these ribbons, accumulate next to the cytopharynx before they become fused with the cytopharyngeal membrane. This fusion allows the nascent food vacuole to grow and increase its membrane surface area. The morphology of this cytostome-cytopharynx region is described in detail and illustrated with a three-dimensional drawing of a portion of this region and a clay sculpture of the oral apparatus of Paramecium. Evidence from the literature for the transformation of food vacuole membrane into disk-shaped vesicles both from condensing food vacuoles in the endoplasm and from egested food vacuoles at the cytoproct is presented. This transformation would complete a system of digestive vacuole membrane recycling.     

Ultrastructural aspects of the somatic and buccal infraciliature ofColeps amphacanthus Ehrenberg 1833

Summary Somatic and buccal infraciliature ofColeps amphacanthus Ehrenberg 1833 were studied by light and electron microscopy. The somatic kineties are composed of monokinetids and 2 dikinetids at the anterior end of each kinety. The monokinetids are associated with postciliary microtubules at triplet 9, a kinetodesmal fiber at triplet 5 and 7 and nearly radially arranged transverse microtubules at triplet 4. The associated fibrillar systems of the posterior kinetosome of the dikinetids are like those of the monokinetids. The anterior kinetosome is associated with transverse microtubules at triplet 4 and one or few postciliary microtubules at triplet 9. The anterior kinetosome bears only a short cilium.The oral ciliature is composed of a kinety of nearly circumorally arranged paroral dikinetids and 3 adoral organelles at the ventral left side of the oral opening. Nematodesmata arising from the oral ciliature form the major component of the cytopharyngeal apparatus which is lined by microtubular ribbons of postciliary origin. The buccal cavity is surrounded by oral papillae which often contain toxicysts.     

New Aspects of the Morphology of Pleurotricha lanceolata (Ciliophora, Hypotrichida): Cirral and Membranellar Patterns and Fibrillar Systems

In Pleurotricha lanceolata, the ventral somatic infraciliature presents 13 frontoventral cirri, 5 transverse cirri, one row with 18–19 left marginal cirri and two rows of right marginal cirri of different length. On the dorsal side there are six longitudinal rows of dorsal bristles, four of them bipolar and the other two less than half body length. The oral infraciliature includes the adoral zone of membranelles, with 45–55 membranelles of three or four rows of kinetosomes each, and two undulating membranes (paroral and endoral membranes), each with two rows of kinetosomes. Some structures of the oral and somatic fibrillar systems have also been examined and are similar to those described in other species of hypotrichous ciliates.     

Etude Ultrastructurale du CiliéKuklikophrya dragescoi gen. n., sp. n.*

SYNOPSIS The cortical infraciliature of Kuklikophrya dragescoi gen. n., sp. n. is composed of double kinetosomes. Each kinetosome has transverse fibers. The anterior transverse fibers are associated with a sheet of dense material and the posterior transverse fibers are directed toward the posterior part of the body. The posterior kinetosome of a pair has only a short protuberance in the position of the kinetosomal fiber. The cortex has a well developed alveolar layer and a thick ecto-endoplasmic boundary. A distinctive characteristic of the buccal ciliature is the circumoral ciliature whose infraciliature is made up of pairs of cilia-bearing kinetosomes. The antero-posterior polarity of the paroral segment is in inverse relationship to that of the remaining ciliature of the organism. The adoral and preoral ciliary organelles consist of 2 rows of kinetosomes, each of which bears postciliary fibers. A frame of nematodesmata surrounds the cytopharynx which is supported by microtubular bands which impart to it a very specific laminated appearance. The “phagoplasm” is formed by “vermicelli”-like vesicles. The micronucleus is found in the perinuclear area of the macronucleus.     

The Functional and Evolutionary Significance of the Ultrastructure of the Ophryoscolecidae (Order Entodiniomorphida)1

ABSTRACT. Ophryoscolecid ciliates from the order Entodiniomorphida show a series of morphological types which have been interpreted as an evolutionary lineage. In this study, ultrastructural information from three species—the ancestral Entodinium, intermediate Eudiplodinium maggii, and the advanced Epidinium—has been evaluated in terms of ophryoscolecid evolution. The infraciliature, nuclei, contractile vacuoles, cortex, and cytoplasm are all very similar and sometimes indistinguishable among the three species, suggesting a close relationship. The cytoalimentary system, however, shows considerable interspecific variation. The cytopharynx differs in position and extent of microtubules and microfilaments, varying in appearance from a microtubular to a microfilament-based mechanism while retaining similar component structures. The esophagus, a zone of cytoplasm extending from the cytopharynx and delimited by a microtubular/fibrillar wall, is rudimentary in Entodinium, sac-like in Eudiplodinium, and tube-like in Epidinium, where it also has convoluted walls and a sheath of fibrous material that suggest an expansible-contractile structure. These variations have been related to type of food particle ingested. The capability of the cytoalimentary systems seems to be increased so that the more advanced forms can exploit a food resource, in the form of large plant fragments in the ruminal fluid, not available to the simpler, ancestral forms, which tend to ingest small particles such as bacteria and starch grains. The original evolutionary lineage based on morphological studies using light microscopy is supported by our observations, in these three forms, of ultrastructural variations in the cytopharynx and in their relationship with diet via possible ingestion mechanisms. Additional support for this evolutionary analysis comes from preliminary studies of other ophryoscolecids in which the cytoalimentary organization is consistent with their positions relative to one another in the evolutionary scheme.     

The Kinetid Structures of the Choreotrichous Ciliate Strobilidium velox and an Assessment of Its Evolutionary Lineage1

The ciliary (kinetid) structures of the ciliate Strobilidium velox have been examined with scanning and transmission electron microscopes. Somatic kineties consist of a linear row of kinetosomes (monokinetids) and short cilia lying partially beneath a thin fold of cytoplasm. The only fibrillar kinetid structure extending from the kinetosomes is a transverse ribbon of microtubules. The paroral membrane is a single-file polykinetid possessing a possible transverse ribbon of microtubules and a nematodesma. The oral polykinetids or membranelles are complex, with microtubules extending from both anterior and posterior rows of cilia. While the kinetid structures do not satisfy the criteria for the order Choreotrichida, they are similar to the tintinnids in several other relevant ways. Strobilidium velox is proposed to be an unusual ciliate that is an exception to the concept that somatic kinetids are conservative and reliable phylogenetic indicator structures.     

Morphogenesis of infraciliature in the entodiniomorphid ciliate Eudiplodinium maggii

The morphogenesis of ciliary zones has been studied in the ciliate Eudiplodinium maggi which has a vestigial somatic infraciliature consisting of subcortical barren kinetosomes. These replicate and migrate into the subequatorial ciliary anlagen of the dividing cells. The kinetid pattern of the barren kinetosomes changes sequentially to that of the ciliary zones. Postciliary and transverse microtubules are derived from basal and cortically directed microtubules while a dense spur coincides with the origin of the kinetodesma. All kinetics produce potential cytopharyngeal components. Nematodesmata originate in granular subkinetosomal dense plates, while two of the three types of cytopharyngeal ribbon are formed from tansverse microtubules. A spatial selectivity ensures that these components extend only from specific kinetids. It is concluded that 91) morphogenesis of the intricate cytoskeletal network of infraciliature involves a “pattern generator” in the vestigial somatic kinetids; and 92) entodiniomorph stomatogenesis in not truly apokinetal but is more like the telokinetal process of related ciliates.     

钩刺目纤毛虫--多核前裂虫的超微结构研究

对钩刺目－土壤纤毛虫－多核前裂虫的超微结构做了透射电镜观察。该种表现了与其他钩刺目种类相似的特征,包括体表分布的粘泡以及扁平的表膜泡,其主要细胞结构特征为：（１）－一层连续的支状内质网将虫体细胞质分成内外两部分;（２）线粒体仅密集于内层细胞质;（３）平行唇突表面的特殊的前列横微管敕纱由胞口发出,沿唇突表层向体后发出并纵行环绕于胞咽外侧,此前列横微管束明显地呈片层状构造;（４）射出体包括位于口区的两     

Calmodulin Localization and its Effects on Endocytic and Phagocytic Membrane Trafficking in Paramecium multimicronucleatum

ABSTRACT. In ciliates, calmodulin (CaM), as in other cells, has multiple functions, such as activation of regulatory enzymes and modulating calcium‐dependent cellular processes. By immunogold localization, CaM is concentrated at multiple sites in Paramecium. It is seen scattered over the cytosol, but bound to its matrix, and is concentrated at the pores of the contractile vacuole complexes and with at least three microtubular arrays. It was localized peripheral to the nine‐doublet microtubules of the ciliary axonemes. The most striking localization was on the akinetic side only of the cytopharyngeal microtubular ribbons opposite the side where the discoidal vesicles, acidosomes and the 100‐nm carrier vesicles bind and move. CaM was also present at the periphery of the postoral microtubular bundles along which the early vacuole moves and was associated with the cytoproct microtubules that guide the spent digestive vacuoles to the cytoproct. It was not found on the membranes of, or in the interior of nuclei, mitochondria, phagosomes, and trichocysts, and was only sparsely scattered over the cytosolic sides of discoidal vesicles, acidosomes, lysosomes, and digestive vacuoles. Together the associations with specific microtubular arrays and the effects of trifluoperazine and calmidazolium indicate that CaM is involved (i) in vesicle transport to the cytopharynx area for vacuole formation and subsequent vacuole acidification, (ii) in early vacuole transport along the postoral fiber, and (iii) in transporting the spent vacuole to the cytoproct. Higher CaM concentrations subjacent to the cell's pellicle and close to the decorated tubules of the contractile vacuole complex may support a role for CaM in ion traffic.