The Nuclear Apparatus of the Ditransversal Ciliate Homalozoon vermiculare (Ciliophora,Rhabdophora) during Interphase and Division. I. The Macronucleus1

ABSTRACT. The nuclear apparatus of Homalozoon vermiculare consists of a single moniliform macronucleus and about 25 micronuclei. The number of macronuclear segments depends (i) on the number of divisions of individual segments during the interphase and (ii) on the number of segments that arise prior to cytokinesis from the (temporary) filiform macronucleus. Precytokinetic changes of the macronucleus involve the fusion of individual segments followed by contraction and subsequent elongation of the entire macronucleus. The chromatin bodies uncoil into fine fibrils during macronuclear contraction. At the time when the division furrow appears, the macronucleus starts to renodulate. The interphase segment contains a more or less reticulated chromatin body partly attached to the nuclear envelope and about 30 polymorphous nucleoli. The latter consist of the pars granulosa, the pars fibrosa, and an additional fibrillar component. The nucleoli undergo drastic changes prior to division and the granular component disappears completely during macronuclear condensation. On the average, the macronucleus contains a 3,400-fold amount of DNA compared with a haploid micronucleus, but the intraspecific differences in the DNA content of the entire macronucleus are extremely large. In contrast, DNA content and size of an individual segment of the macronucleus are precisely regulated during interphase.     

Mitosis of Micronuclei During Division and Regeneration in the Ciliate Stentor coeruleus1

Stages of mitosis of the micronuclei of Stentor coeruleus were described as seen by transmission electron microscopy. Cells in division and those regenerating new oral membranelles were studied. Microtubules were found in early prophase in the karyoplasm and interspersed between the condensing chromatin. A monaxial intranuclear spindle is formed by early metaphase, with kinetochore microtubule attachment sites on the chromosomes. The spindle elongates, separating the daughter nuclei at anaphase. A new nuclear envelope, consisting of two unit membranes, begins to form at late anaphase. Small segments of membrane found in the space between the newly forming and the old micronuclear envelopes appear to fuse to form the new nuclear envelope. No ultrastructural differences were found in the mitotic nuclei of cells in division or regeneration.     

Ultrastructure of Prorodon (Ciliophora, Prostomatida) Ii. Oral Cortex and Phylogenetic Conclusions

ABSTRACT. The ultrastructure of the oral region and the ultrastructural architecture of the basket of Prorodon aklitolophon and Prorodon teres are described. the oral region of Prorodon consists of: 1) A circumoral kinety at the anterior pole of the cell surrounding the typically slit-shaped cytostomial funnel. This kinety is composed of inversely oriented dikinetids in which both kinetosomes are ciliated and are associated with a very short postciliary microtubular ribbon and a few transverse microtubules; 2) Three brush rows aligned in parallel and extended meridionally in the anterior part of the cell. the individual brush rows consist of dikinetids, but in contrast to the dikinetids around the cytopharynx they are not inverted and only the anterior kinetosomes bear specialized short brush cilia and are associated with a divergent-tangential transverse microtubular ribbon. the posterior kinetosome is non-ciliated and bears a prominent convergent postciliary microtubular ribbon. Schematized dikinetid patterns of both oral regions of Prorodon are provided. In addition, a three-dimensional reconstruction of the basket of the genus Prorodon based on serial thin sections is presented. A phylogenetic tree, mainly based on stomatogenic data, is given to show the phylogenetic relationships of some prostomatid genera as well as the hypothesized sistergroup relationship of colpodid and prostomatid ciliates.     

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 .     

Phylogeny and Systematic Position of Zosterodasys (Ciliophora, Synhymeniida): A Combined Analysis of Ciliate Relationships Using Morphological and Molecular Data

ABSTRACT. The Synhymeniida is characterized both by a band of somatic dikinetids, the synhymenium, extending across the surface of the cell and by a ventral cell mouth lacking specialized feeding cilia but subtended by a well-developed cyrtos. The synhymeniids have been hypothesized to be members of the class Nassophorea but our previous ultrastructural study of the synhymeniid genus Zosterodasys did not show any clear synapomorphies that would permit definitive placement in the Nassophorea or as a sister taxon to any of the other ciliate groups possessing a cyrtos. In the present study, simultaneous analysis of morphological and small subunit rDNA molecular data indicates that the Synhymeniida are sister to the class Phyllopharyngea and that this clade is, in turn, sister to the remaining Nassophorea, although this result is sensitive to dataset inclusion and alignment parameters. While this suggests that taxa with a ventral cyrtos might be united into a named taxon (e.g. resurrecting the Hypostomata), additional data are needed to reach a definitive conclusion.     

Morphology,Conjugation, and Postconjugational Reorganization of Dileptus tirjakovae n. sp. (Ciliophora,Haptoria)

ABSTRACT. We studied the morphology, conjugation, and postconjugational reorganization of a new haptorid ciliate, Dileptus tirjakovae n. sp., using conventional methods. Dileptus tirjakovae is characterized by two abutting, globular macronuclear nodules and scattered brush kinetids. Conjugation is similar to that in congeners, that is, it is temporary, heteropolar, and the partners unite bulge‐to‐bulge with the proboscis. Some peculiarities occur in the nuclear processes: there are two synkaryon divisions producing four synkaryon derivatives, of which two become macronuclear anlagen, one becomes the micronucleus, and one degenerates. Unlike spathidiids, D. tirjakovae shows massive changes in body shape and ciliary pattern before, during, and after conjugation: early and late conjugants as well as early exconjugants resemble Spathidium, while mid‐conjugants resemble Enchelyodon. These data give support to the hypothesis that spathidiids evolved from a Dileptus‐like ancestor by reduction of the proboscis. Dileptus tirjakovae exconjugants differ from vegetative cells by their smaller size, stouter body, shorter proboscis, and by the lower number of ciliary rows, suggesting one or several postconjugation divisions. Although 83% of the exconjugants have the vegetative nuclear pattern, some strongly deviating specimens occur and might be mistaken for distinct species, especially because exconjugants are less than half as long as vegetative cells.     

Colpoda spiralis sp. n., a Colpodid Ciliate Found Inhabiting Treeholes (Colpodida,Ciliophora)*

SYNOPSIS A new species of the family Colpodidae, genus Colpoda O. F. Müller, Colpoda spiralis sp. n. is described. This organism has been found only in treehole fluid. Its species status is based on the possession of a unique and prominent preoral protuberance, multimicronuclearity, and the preference for a treehole habitat. Its range is known to include the tri-state area of Arizona, New Mexico and Utah, and the mixed-deciduous forests of Maryland. This species prefers treehole fluids with a pH > 7 and is naturally limited to tree species which possess these alkaline treeholes. It encysts as a treehole dries and excysts when the treehole is again filled by fluids from the tree, or rainwater.     

Macronuclear Events and Some Morphogenetic Details During the Excystment of Onychodromus acuminatus (Ciliophora, Hypotrichia)

Light microscopy of stained (protargol, Feulgen, aceto-orcein, methyl green-pyronin) specimens of Onychodromus acuminatus during excystment shows that the macronucleus appears during the first hour as a warped ribbon with variable density and width and with sharpened ends. One extraordinary point that reaches the cortex is frequently seen in front of a small granule where the bundle of positioning fibers arises. The macronucleus returns to its previous form, with rounded edges, at the end of cortical morphogenesis, and later divides twice. Some details of cortical morphogenesis during the excystment process are discussed.     

Corticocolpoda kaneshiroae N. G., N. Sp., a New Colpodid Ciliate (Protozoa, Ciliophora) from the Bark of Ohia Trees in Hawaii

Corticocolpoda kaneshiroae n. g., n. sp. was discovered in the bark of Ohia trees (Metrosideros polymorpha) from the Hawaiian Archipelago. Its morphology and infraciliature were studied in live cells, with the scanning electron microscope, as well as in specimens impregnated with protargol, silver nitrate, and silver carbonate. The new genus, Corticocolpoda, belongs to the family Colpodidae and is unique in having a left oral ciliary field (polykinetid) composed of 13–20 equidistantly spaced, paired rows of monokinetids. The new species, C. kaneshiroae, measures 100–300 × 60–250 μm and has a huge vestibulum used to capture large food items, mainly other ciliates. The oral ciliary fields are within the vestibulum and of equal length; the right field is a paroral membrane composed of a single row of dikinetids. Several micronuclei are attached to the ellipsoid macronucleus. The mucocysts are inconspicuous and arranged around the somatic dikinetids. The resting cyst is globular and has a 1–2 μm thin, firm, yellowish inner wall and a 20-μm-thick, fragile, hyaline outer wall. Convergent evolutionary paths and a possible polyphyly of the Colpodidae are discussed. An improved key to the genera of the family Colpodidae is provided. Twenty-three species of ciliates and one flagel***iate (Hemimastix amphikineta), which occurred together with C. kaneshiroae, are new for the fauna of Hawaii and listed in the ecology section.     

The Fine Structure of Saprodinium dentatum Lauterborn, 1908 as a Representative of the Odontostomatida (Ciliophora)

The fine structure of the sapropelic ciliate Saprodinium dentatum is described based on phase-contrast microscopy, silver-staining techniques, cryo-fracture scanning electron microscopy, and thin sections. The study concentrates on a detailed analysis of the somatic cortex and the oral ciliature of this highly asymmetric, laterally compressed ciliate. The cell shape is dominated by a number of site-specific spines and the curving course of 10 somatic kineties (SK 1–10). The SK, composed of dikinetids, show an intrakinety differentiation that seems characteristic for other odontostomes as well. The anterior segment of the SK is mostly ciliated, followed by a non-ciliated segment in which the kinetosomes lack all typical fiber systems. Except for SK 4–6, the posterior segment is ciliated again, forming the spine kinetics associated with particular caudal spines. The anterior segment of SK 3 through SK 7 form the frontal band, which together with the two frontal kineties constitutes the main locomotory organelle for a ciliate that creeps on the substratum. A short kinety with inverse polarity, not seen in earlier light microscopical studies, was observed near the oral spine. We made particular effort to find a logical explanation for the observed association of the SK with the various caudal spines. The oral ciliature consists of nine adoral organelles located in a tripartite oral cavity. The absence of a paroral ciliature together with the position of the cytostome anterior to the adoral organelles may be the result of rotational movement of the oral apparatus during the evolution of these bizarre ciliates. Results are discussed with special reference to the phylogenetic relationship of the Odontostomatida to the Heterotrichida and no conclusive answer was found in this first electron microscopical study of an odontostomatid ciliate.     

The Order Euplotida (Ciliophora): Taxonomy, with Division of Euplotes into Several Genera

ABSTRACT. The order Euplotida represents a monophyletic order of five families of hypotrich ciliates united by morphology, stomatogenesis, ultrastructure, cyst structure, and behavior. A review of variability of ciliation and nuclei among the 14 genera suggests that lines of evolution may have involved both the loss of cirri and nuclear simplification. We present a binary key to genera in the families Aspidiscidae ( Aspidisca and Euplotaspis ), Certesiidae n. fam. ( Certesia ), Gastrocirrhidae ( Cytharoides, Euplotidium , and Gas-trocirrhus ), Uronychiidae ( Diophryopsis, Diophrys, Paradiophrys , and Uronychia ), and Euplotidae. The latter family contains species formerly in the genus Euplotes. Based primarily on cortical structure, endosymbionts, data from morphometric analysis, and ecology, we recognize four different groups. The first group of species remains in Euplotes with Euplotes charon as type. We place a second group of species into the genus Moneuplotes Jankowski 1979 with Moneuplotes vannus (Müller, 1786) as type. We erect two new genera: Euplotoides n. g. and Euplotopsis n. g. with Euplotoides patella (Müller, 1773) n. comb. and Euplotopsis affinis (Dujardin, 1841) n. comb. as type species respectively. We discuss possible phylogenetic relationships within the order.     

Growth, Fine Structure and Cyst Formation of a Microbial Mat Ciliate: Pseudocohnilembus pusillus (Ciliophora, Scuticociliatida)

ABSTRACT Pseudocohnilembus species exhibit a polymorphic life cycle consisting of trophic cells, theronts, and cysts. Pseudocohnilembus pusillus isolated from the intertidal mats of Laguna Figueroa, Baja California Norte, Mexico, forms desiccation-resistant cysts in response to bacterial food depletion. This isolate is a euryhaline organism, able to grow at salinities from freshwater to 96 ppt total salinity and from pH 6–9. Electron micrographs show that oral and somatic cilia and kinetids are retained inside young cysts. Cyst walls are composed of a single layer (0.1 μm) of granular material. Under all conditions, as bacterial food was depleted, P. pusillus cells formed cysts, except for a small proportion (1–5%) that continued to swim. Changes in pH and salinity did not directly induce cyst formation. Salinity did greatly affect growth rate. Doubling times were shortest at 16 ppt salinity and at pH 7–8. Cyst formation occurred later in the growth cycle as more food bacteria were added. Additionally, ciliates grown in small culture volumes (10 ml) formed cysts sooner than cultures in larger volumes (100 ml), suggesting that crowding may influence cyst formation. Mature cysts may survive desiccation at least as long as one month at 37° C and for as long as one year at 20 ± 3° C. Although trophic cells did not survive desiccation or anoxia, encysted ciliates from liquid stationary phase cultures kept in anoxic seawater for one month excysted into swimming cells within 2.5 h after exposure to air. The adaptability of P. pusillus to extremes of salinity, pH, desiccation, and anoxia permits survival in its environmentally variable, microbial mat habitat.     

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.     

Light and Electron Microscope Observations On Presporogonic and Sporogonic Stages of Sphaerospora Epinepheli (Myxosporea) In Grouper (Epinephelus Malabaricus)

ABSTRACT. Presporogonic (blood) stages of Sphaerospora epinepheli Supamattaya, Fischer-Scherl. Hoffmann, Boonyaratpalin, 1990 were observed in the circulating blood, sinus of kidney, glomerurar capillaries and liver arteries of grouper Epinephelus malabaricus. the earliest detectable stage was a primary cell with one secondary cell. After cell divisions, nine to 16 secondary cells were found in one primary cell. Ultrastructural examination revealed electron-dense bodies (118-145 nm) in the cytoplasm of primary cells. Sporogonic stages and spores were located in Bowman's space and in kidney tubule lumens. Electron micrographs revealed a similar pattern of spore development as described from other Sphaerospora spp. Kidneys infected with S. epinepheli showed highly vacuolated tubular epithelial cells and severely affected renal corpuscles.     

Mitosis of the free-living flagellate Bodo saltans strain Ps+ (Kinetoplastidea, Bodonida)

Mitosis of the free-living flagellate Bodo saltans of the Ps+ strain characterized by the presence of prokaryotic cytobionts in the perinuclear space was studied. Division of B. saltans Ps+ nuclei occurs by the closed intranuclear type of mitosis without condensation of chromosomes. At the initial stages of nuclear division, consecutive anlage of two spatially separated microtubular spindles begins. The spindle containing about 20 microtubules appears first, then, at an angle of 30–40° to it, the second spindle containing half as many microtubules is formed. The microtubules of the first spindle are associated with 4 pairs of kinetochores, the microtubules of the second one—with 2 pairs. The kinetochores of B. saltans Ps+ have a pronounced laminar structure. Both spindles rest with their ends directly on the internal membrane of the nuclear envelope and form 4 well-pronounced poles. The equatorial phase of mitosis in B. saltans Ps+ is not revealed. The divergence of sister kinetochores towards the poles occurs independently in each spindle. At the elongation phase of mitosis, the poles of both spindles are united in pairs to form a single bipolar structure composed of two loose bundles of microtubules. At this stage of nuclear division, the kinetochores reach the poles of the subspindles and cease to be visible. At subsequent nuclear division stages the nucleus acquires a dumbbell shape. During the reorganization phase the sister nuclei are separated. In the perinuclear space of the interphase nuclei of B. saltans Ps+, 1–2 prokaryotic cytobionts are present. In the course of mitosis, these organisms divide intensively, such that their number can reach 20 and more per nucleus. During separation of sister nuclei, the “excessive” cytobionts are released into the cytoplasmic vacuoles formed by external membranes of the nuclear envelope.     

Description of the Infraciliature and Morphogenesis in the Ciliate Urotricha ondina N. Sp. (Prorodontida, Urotrichidae)

Recent works on prostomatid ciliates show that some genera of this group have a differentiated oral infraciliature and that their stomatogenesis during division involves the proliferation of only a few somatic kineties. These findings have significant implications regarding the iaxonomic status of these genera and also on the terminology used for the oral structures. In Urotricha ondina , the oral infraciliature consists of (1) a paroral kinety formed of paired kinetosomes that encircle the cytostome at the anterior pole of the cell and (2) 3 adoral organelles, each formed of 2 rows of kinetosomes, ventral in position and obliquely disposed, lying above 3 short somatic kineties that do not reach the anterior pole of the cell. This oral ciliature —formerly known as the corona and brosse, respectively—originate during stomatogenesis from the proliferation of 4 somatic kineties that lie posterior to the adoral organelles of the parental cell.     

管氏肿腿蜂毒液器官超微结构观察

应用透射电镜技术,观察了管氏肿腿蜂Scleroderma guani毒液器官的超微结构.毒腺由基膜层、分泌细胞层、导管细胞层和内膜层构成,分泌细胞内含内质网、末端附器、分泌囊泡、分泌颗粒、液泡等细胞器,其内合成的毒液由末端附器输送至毒腺的腔体.毒囊由肌肉鞘层、上皮细胞层和内膜层组成,肌肉鞘内的肌纤丝规则排列不交错,上皮细胞层内细胞器稀少,内膜层呈波浪状均匀加厚.     

On the Cytology and Fine Structure of the Neogregarine Syncystis aeshnae Tuzet and Manier, 1953 (Apicomplexa, Syncystidae)

The neogregarine Syncystis aeshnae Tuzet and Manier, 1953, was obtained from two species of dragonfly larvae, Aeshna grandis and Libellula quadrimaculata , collected in southern Sweden. Merogony, gamogony, and sporogony were observed in the adipose tissue, which was destroyed, and the haemocoele. Merozoites had a traditional apical complex. Gamonts associated in pairs did not unite conoid-to-conoid, and the border between gamonts was not found to break down. Each association produced 32 spores in bilobed gametocysts. Spores were elongate, oval, 4.0–5.8 × 8.0–10.0 μm in fixed and stained condition, each with 4+4 terminal and four equatorial thread-like projections. The thick-walled spore is considered the sporocyst. Species identification, ultrastructural cytology, and problems associated with using the terms oocyst and sporocyst are discussed.