Cytokinesis of Thuricola folliculata (Ciliophora,Peritrichida)1

Thuricola folliculata is a sessiline, loricate peritrich ciliate. Its somatic pellicle consists of annular transverse crests and includes the plasma membrane, the alveolus, the electron-dense epiplasm, and the subepiplasmic layer. Cytokinesis occurs along an oral-aboral median plane where two fissures develop, one at the oral and one at the aboral end of the peritrich. Each fissure results from simultaneous formation of two furrows on opposite sides of the cell. At the end of cytokinesis, both trophozoites remain joined to each other by an intercellular bridge. During cytokinesis, microfilament bundles appear at the level of the subepiplasmic layer in the fission plane; they are distributed in two arcs, one oral and one aboral, and may be responsible for the formation of the four furrows. The cross-sectioned microfilament arc is 1 pm wide and about 0.1-0.2 pm thick at first and later can be more than 1 pm in diameter; it shows many microfilaments, 3-10 nm in diameter and oriented parallel to the fission plane, and also many dense corpuscles 25-55 nm in diameter. Then both arcs join each other to form a microfilament ring. This ring is delimited by discontinuous dense borders and a boundary layer. The microfilament ring seems structurally analogous to the contractile ring of various dividing cells, where it works like a sphincter. The dense corpuscles, the discontinuous dense borders, and the boundary layer of T. folliculata have not been reported in any other ciliates.     

The Stomatogenic Process in Opercularia coarctata (Ciliophora, Peritrichida)

ABSTRACT. Stomatogenesis in Opercularia coarctata has been studied in specimens treated with Fernández-Galiano's silver impregnation method. The new buccal structures originate from the germinal row and from the parental haplokinety.     

Fine Structure of Pseudokeronopsis carnea (Ciliophora,Hypotrichida)1

ABSTRACT Two kinds of pigment structures, pigment vacuoles and pigmentocysts, cause the orange-red color of Pseudokeronopsis carnea (Cohn, 1866). The pigment vacuoles are undischargeable and two to five layers of them form a characteristic ectoplasmic zone. The pigmentocysts mainly surround the infraciliature and show a unique channel which is probably used for extrusion. Previous data on the fine structure of subpellicular granules and extrusomes of hypotrich ciliates are summarized. Their obviously diverse organization argues for a great value of these structures in species identification. The basic structural features of the infraciliature and the cytoplasmic organelles of P. carnea are similar to those found in other hypotrichs; however, a special kind of linear microtubular array borders the longer sides of the cirral bases and the margins of the adoral membranelles and those of the membranes in the right buccal area. To the left of the endoral membrane, these microtubular arrays result in a highly ordered structure reminiscent of oral ribs. This peculiar arrangement of microtubules in cirri and paramembranelles has also been found in the related form, Thigmokeronopsis jahodai, probably indicating a homogeneity of the fine structure of urostylid hypotrichs. In P. carnea, the basal bodies of the paroral membrane are proximally connected like a polykinetid. Its cilia are unlinked, whereas those of the endoral membrane are fused by microfibrillar material. The terms diplostichomonad and polystichomonad only refer to quantitative aspects and omit the evident, high diversity of microtubular and microfibrillar associates occurring in the membranes in the right buccal area. These terms need to be redefined on the basis of more material that is better described.     

Effect of Cytochalasin B on the Cytokinesis of Thuricola folliculata (Ciliophora,Peritrichida)1

ABSTRACT. Binary fission of the sessiline loricate peritrich Thuricola folliculata was examined by light microscopy. Cytokinesis, which occurs in the oral-aboral median plane, is 35-40 min in duration. Cytochalasin B (CB) was used at final concentrations of 50–100 μg/ml in dimethyl sulfoxide (DMSO). A transition point occurs at about 20 min after the beginning of binary fission and about 10 min before cytokinesis. In most cases, 50 μg/ml and 100 μg/ml CB added to cells before the transition point resulted in delays of cytokinesis which were significant compared to DMSO controls; sometimes, cytokinesis was blocked completely. If added after the transition point, CB had no effect on cells.     

Trichodinid Protozoa (Ciliophora: Peritrichida) from Freshwater Fishes of Rybinsk Reservoir,USSR1

During the spring of 1981, trichodinid protozoa were collected from the gills or urinary bladder of the following species of fishes of Rybinsk Reservoir, USSR, located on the upper reaches of the Volga River system: Esox lucius, Rutilus rutilus, Leuciscus idus, Blicca bjoerkna, Abramis ballerus, Pelecus cultratus, Lota lota, and Perca fluviatilis. A total of 13 species of Trichodinidae was recovered from Rybinsk fishes, among which are three new species of the genus Trichodina: T. izyumovae n. sp. from the gills of L. idus, T. borokensis n. sp. from the gills of P. cultratus, and T. kupermani n. sp. from the gills of A. ballerus. Other species of trichodinids reported are T. modesta Lom, 1980; T. nigra Lom, 1969; T. pediculus (O. F. Müller, 1786); T. prowazeki Grupcheva & Lom, 1980; T. rostrata Kulemina, 1968; T. urinaria Dogiel, 1940; T. ophiocephalus Kostenko & Karaev, 1976; Paratrichodina incisa (Lom, 1959); Trichodinella epizootica (Raabe, 1950); and Tripartiella copiosa Lom, 1959. Photomicrographs and morphometric data are presented for each species and aspects of their host and geographic distribution discussed. Trichodina algonquinensis Li & Desser, 1983 is considered a synonym of T. urinaria Dogiel, 1940.     

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.     

The Fine Structure of the Cinctum of Ellobiophrya conviva (Ciliophora: Peritricha)

Ellobiophrya conviva clasps tentacles of the bryozoan Bugula neritina with a ring-like structure formed from aboral extensions of its body that taper into two slender arms. The tips of the arms overlap and join to form a unique organelle, the bouton. Each arm contains a massive myoneme that splays out at the bouton. The bouton consists of the cupped tips of the arms and a cavity, which is filled with dense homogeneous material. Long digitations containing longitudinal microtubules at their periphery project from the inner surface of the tip of each arm into the cavity. Deep folds of pellicle with pores opening into their depths line the wall of the cavity. Conventional kinetosomes are not visible in the bouton, but circular or elliptical arrays of microtubules are found at the bases of digitations. The nonfunctional scopula of the adult is in a depression enclosed by pellicular folds. The bouton is distant from the scopula, but its fine structure somewhat resembles it, supporting Chatton and Lwoff's hypothesis that the cinctal arms carry parts of the scopula at their tips. The fine structure of the cinctum supports their suggestion that the cinctal arms are homologous to the spasmonemes of vorticellid peritrichs.     

Trichodinid ectoparasites (Ciliophora: Peritrichida) of some River Nile fish, Egypt

Four species of trichodinid ectoparasites (Ciliophora: Peritrichida) were collected from the gills of the following River Nile fish in Egypt: Hydrocynus forskalii, Mormyrus kannume, Schilbe mystus. These species are: Trichodina heterodentata Duncan, 1977, Trichodina fahaka sp. n., Trichodinella epizootica Raabe, 1950, Tripartiella dactylodentata sp. n. Photomicrographs and morphometric data are presented for each species.     

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.     

Species Structure in Euplotes crassus (Ciliophora, Hypotrichida)

ABSTRACT. We observed different low salinity tolerances between two groups of populations of Euplotes crassus. After mating analysis, the less tolerant populations could be assigned to three mating groups. Two of them were separated by preconjugative barriers but both conjugated with a third one. A breeding test showed evidence of (potential) introgression mediated by this bridging group. On the other hand, the more tolerant populations formed a fourth mating group unable to conjugate with the others and characterized by distinct zymogram patterns. We conclude that natural introgression among the studied populations is not complete and that the species structure of E. crassus comprises intrafertile sets of populations among which gene flow may be difficult or virtually absent.     

Trichodinid ectoparasites (Ciliophora: Peritrichida) of wild and cultured freshwater fishes in Taiwan,with notes on their origin

During 1988 parasitological surveys were carried out on the freshwater fish fauna on the island of Taiwan in 12 localities that included fishery stations, reservoirs, fish markets as well as natural rivers and swamps. A total of 28 fish species were examined, representing 14 families. This paper reports on the parasites of the genus Trichodina (Ciliophora, Peritrichida) of Taiwan. Fourteen trichodinid species were recorded of which five are new. Trichodinids collected in this study can be divided into four categories, based on their host association and possible region of origin. The first category includes trichodinids with an African origin, T. centrostrigeata Basson, Van As & Paperna, 1983, T. heterodentata Duncan, 1977, T. compacta Van As & Basson, 1989 and possibly T. canton n. sp. The second category is species with an Eurasian origin and includes T. acuta Lom, 1961, T. modesta Lom, 1970, T. mutabilis Hirschmann & Partsch, 1955, T. nigra Lom, 1961 and T. nobilis Chan, 1963. The third category comprises one species, T. maritinkae Basson & Van As, 1990, with an Afro-Asian distribution. The last category is composed of new species that are most likely native to Asia: these are T. matsu n. sp., T. mandarin n. sp., T. wulai n. sp. and T. pagoda n. sp.     

Two new species of Epistylis (Ciliophora: Peritrichida) on the blue crab (Callinectes sapidus) in the Gulf of Mexico

Two epibiotic peritrichs infested the blue crab, Callinectes sapidus, from the Gulf of Mexico, Mississippi, USA. Epistylis callinectes n. sp. was isolated from the epipods of maxillipeds, bases of gill-cleaning setae, and gills, and Epistylis clampi n. sp. was isolated from the exterior surfaces of the exoskeleton. Epistylis callinectes has short, symmetrically and dichotomously branched stalks; its zooid is elongate ovoid and conspicuously longer than the individual stalk branches, measuring 40-57 (49) x 18-33 (26) microm in vivo and containing a thick, undivided peristomial lip (PL). It has a single contractile vacuole and a transverse horseshoe-shaped macronucleus. Its haplokinety (H) and polykinety (Po) complete one and one-half circuits on the peristome before entering the infundibulum. There is a distal kinetal fragment present at the distal end of both the H and Po. Epistylis callinectes has 48-70 transverse silverlines from the oral area to the trochal band (TB) and 19-26 from the TB to the scopula. Epistylis clampi has long, asymmetrically, and dichotomously branched stalks. Its zooid is elongate vase-shaped, measuring 35-64 (48) x 21-30 (27) microm in vivo and with a thick, transversely folded PL. The stalks supporting zooids are unequal in length. Its zooid has a single contractile vacuole and a transverse horseshoe-shaped macronucleus occurs in the upper half of the body. Its H and Po complete approximately one circuit around the peristome before entering the infundibulum. There is a distal kinetal fragment present at the distal end of both the H and Po. This species has 71-112 transverse silverlines from the peristome to the scopula.     

A New Flagship Peritrich (Ciliophora,Peritrichida) from the River Rhine,Germany: Apocarchesium arndti n. sp.

ABSTRACT. We discovered a free‐living peritrich ciliate with outstanding features in the River Rhine. Its morphology and 18S rRNA gene sequence were studied with standard methods. Apocarchesium arndti n. sp. has several peculiarities. (i) There are ordinary zooids, macrozooids, and microzooids, which form a hemispherical rosette on a discoidal base, the stalk dish, locking the ～18 μm wide and up to 2 mm long, spirally contracting colony stalk. (ii) The stalk myoneme is connected only to the microzooids. (iii) A rosette contains up to 50 zooids not connected to each other but individually attached to the stalk dish with the scopula. (iv) The ordinary zooids are epistylidid, trumpet‐shaped (～6:1 length:width), about 180 × 30 μm in size, and have an ellipsoidal macronucleus subapically between oral cavity and dorsal side. (v) The myoneme system of the zooids, which can contract individually, forms a tube‐like structure in the narrow posterior half of the cell. (vi) The silverline pattern belongs to the transverse‐striate type. (vii) The oral apparatus is of usual structure, with kinety 1 of peniculus 3 distinctly shortened proximally. (viii) The 18S rRNA places A. arndti n. sp. as a distinct lineage near Vorticella and Carchesium. These data are used to provide an improved diagnosis of the genus Apocarchesium. Features (i)–(iii) and the molecular data indicate that Apocarchesium could be the type genus of a new peritrich family.     

Trichodinid ectoparasites (Ciliophora: Peritrichida) of freshwater fishes of the Zambesi River System,with a reappraisal of host specificity

Over a period of five years parasitological surveys were carried out on the freshwater fish fauna in the eastern Caprivi which included the upper Zambesi River, a section of the Chobe and Kwando Rivers, and vast swampy areas. This area is well known for its wide variety of indigenous fish and has so far not been influenced in any way by introduced alien fish species. In these surveys 45 different fish species of 12 families were examined. This paper reports on the parasites of the generaTrichodina andHemitrichodina of the eastern Caprivi. A total of 15 species of parasites were recorded of which nine are new species described here-in. The list of host records of known species are expanded and an evaluation of host specificity based on information recorded in this survey as well as previously published data from southern Africa is provided.     

小球藻绿钟虫--中国东北淡水生缘毛类纤毛虫的形态学重述

小球藻绿钟虫 (VorticellachlorellataStiller ,194 0 )采自哈尔滨附近水域。本文在活体观察基础上 ,利用蛋白银染色技术对其形态学进行了研究 ,给出了该种染色后的特征。小球藻绿钟虫因其细胞内充满共生小球藻呈鲜绿色而得名。该种自然伸展时呈稳定的矮钟状 ,体长 5 3- 6 3× 4 1- 6 2 μm ;大核“J”型 ,两端明显盘绕 ,纵贯于体内。细胞表面具横纹 ,蛋白银制片后可见从口围唇到反口纤毛环之间有 33- 36条纹 ,从反口纤毛环到帚胚有条纹 15 - 18条 ;第三咽膜 (P3)由三列毛基列组成 ,最内侧一列长度仅是另外两列的一半 ,并显著分离 ;口围盘纤维斜向并呈轮辐式放射状排列 ,纤维末端分叉。通过对本文描述的绿色钟虫—小球藻绿钟虫的研究 ,发现对绿色钟虫的描述与归属问题仍存在一些混淆。本文认同将小球藻绿钟虫与绿钟虫严格分立的观点     

Fine Structure of the Sporogonic Stages of Nosema parkeri

SYNOPSIS The fine structure of sporogonic stages of Nosema parkeri Krinsky, a microsporidan from the argasid tick, Ornithodoros parkeri Cooley, is described. Developmental changes in the spore coat and cytoplasmic organelles are discussed. As a sporoblast transforms into a spore, the organelles become more compact and the membranes surrounding them appear to become more taut. It is suggested that the polaroplast complex is involved in fluid transport during development of the spore. Organelles in the mature spore include 2 contiguous nuclei enveloped in a lattice containing ribosome-like particles, a polaroplast complex composed of laminar and saccular regions, and a coiled tubular polar filament attached to a polar sac. Sporogonic stages do not appear to have mitochondria, Golgi apparatus, or a posterior vacuole. The fine structure of the spore of N. parkeri is very similar to that of species of Nosema found in insects, crustaceans, and trematodes.     

Trichodina sp. (Ciliophora: Peritrichida) in eel Anguilla anguilla in recirculation systems in denmark: host-parasite relations

Farmed eel cultured in recirculation systems in Denmark were found infected by Trichodina jadranica Raabe, 1958. Associations between parasite abundance and fish size was examined in 2 different production systems. In one system, stocked with relatively well-nourished eels (3 to 31 g), most of the parasites (66%) were found on the dorsal part on the skin and relatively few were found on the gills (approx. 8%). The infection level was significantly positively correlated both with fish weight and length. In the other system, stocked with relatively malnourished small eels (0.5 to 4 g), significantly more parasites (0.06 +/- 0.02 [SD]) were present on fish with a low condition factor than on fish with a higher condition factor (0.13 +/- 0.01 [SD]). In this eel stock the vast majority of the trichodines were found on the gills.     

Morphological and Molecular Characterization of Some Peritrichs (Ciliophora: Peritrichida) from Tank Bromeliads, Including Two New Genera: Orborhabdostyla and Vorticellides

Using standard methods, we studied the morphology and 18S rDNA sequence of some peritrich ciliates from tank bromeliads of Costa Rica, Jamaica, and Ecuador. The new genus Orborhabdostyla differs from Rhabdostyla by the discoidal macronucleus. Two species from the literature and a new species from Ecuadoran tank bromeliads are combined with the new genus: O. previpes (Claparède and Lachmann, 1857) nov. comb., O. kahli (Nenninger, 1948) nov. comb., and O. bromelicola nov. spec. Orborhabdostyla bromelicola is a slender species with stalk-like narrowed posterior half and operculariid/epistylidid oral apparatus. An epistylidid relationship is also suggested by the gene sequence. Vorticella gracilis, described by Dujardin (1841) from French freshwater, belongs to the V. convallaria complex but differs by the yellowish colour and the number of silverlines. The classification as a distinct species is supported by the 18S rDNA, which differs nearly 10% from that of V. convallaria s. str. Based on the new data, especially the very stable yellowish colour, we neotypify V. gracilis with the Austrian population studied by Foissner (1979). Vorticella gracilis forms a strongly supported phyloclade together with V. campanula, V. fusca and V. convallaria, while Vorticellides astyliformis and Vorticella microstoma branch in a separate, fully-supported clade that includes Astylozoon and Opisthonecta. The new genus Vorticellides comprises five small (usually < 60 μm), barrel-shaped species with two epistomial membranes: V. aquadulcis (Stokes, 1887) nov. comb., V. astyliformis (Foissner, 1981) nov. comb., V. platysoma (Stokes, 1887) nov. comb., V. infusionum (Dujardin, 1841) nov. comb., and V. (Spinivorticellides) echini (King, 1931) nov. comb. Two of these species are redescribed in the present study: V. astyliformis and V. aquadulcis, which is neotypified with a Costa Rican population. Pseudovorticella bromelicola nov. spec. differs from the congeners by the location of the two contractile vacuoles and the number of silverlines.     

Five New Species of Lagenophrys (Ciliophora,Peritricha, Lagenophryidae) from the United States with Observations on Their Developmental Stages1

Five species of the loricate genus Lagenophrys were found on freshwater hosts and are described for the first time. Lagenophrys dennisi n. sp., L. incompta n. sp., and L. oregonensis n. sp. are ectosymbionts of astacid crayfish. Lagenophrys foxi n. sp and L. missouriensis n. sp. are ectosymbionts of gammarid amphipods. All five species appear to occur only m North America. Protargol preparations of the five species reveal that the peristomial myoneme is much broader and more extensive in telotrochs and metamorphosing individuals than in adults. Darkly staining bands appearing to be somatic myonemes were also seen underneath the surface of the body and in the center of the body of telotrochs and metamorphosing individuals. The telotroch of Lagenophrys is so different from the adult that it constitutes a true larval form rather than a simple dispersal stage. Structural parallels between the telotroch of Lagenophrys and mobiline peritrichs suggest the hypothesis that mobilines evolved from the telotroch of a sessiline pentrich which had first evolved into a true larval form.