Peritrich Ciliate Research Articles

High-Level Genetic Diversity but No Population Structure Inferred from Nuclear and Mitochondrial Markers of the Peritrichous CiliateCarchesium polypinumin the Grand River Basin (North America)

Studies that assess intraspecific genetic variation in ciliates are few and quite recent. Consequently, knowledge of the subject and understanding of the processes that underlie it are limited. We sought to assess the degree of intraspecific genetic variation in Carchesium polypinum (Ciliophora: Peritrichia), a cosmopolitan, freshwater ciliate. We isolated colonies of C. polypinum from locations in the Grand River basin in Southwestern Ontario, Canada. We then used the nuclear markers--ITS1, ITS2, and the hypervariable regions of the large subunit rRNA--and an 819-bp fragment of the mitochondrial cytochrome c oxidase I gene (cox-1) to investigate the intraspecific genetic variation of C. polypinum and the degree of resolution of the above-mentioned markers at the population level. We also sought to determine whether the organism demonstrated any population structure that mapped onto the geography of the region. Our study shows that there is a high degree of genetic diversity at the isolate level, revealed by the mitochondrial markers but not the nuclear markers. Furthermore, our results indicate that C. polypinum is likely not a single morphospecies as previously thought.

Sulfide assimilation by ectosymbionts of the sessile ciliate, Zoothamnium niveum.

We investigated the constraints on sulfide uptake by bacterial ectosymbionts on the marine peritrich ciliate Zoothamnium niveum by a combination of experimental and numerical methods. Protists with symbionts were collected on large blocks of mangrove-peat. The blocks were placed in a flow cell with flow adjusted to in situ velocity. The water motion around the colonies was then characterized by particle tracking velocimetry. This shows that the feather-shaped colony of Z. niveum generates a unidirectional flow of seawater through the colony with no recirculation. The source of the feeding current was the free-flowing water although the size of the colonies suggests that they live partly submerged in the diffusive boundary layer. We showed that the filtered volume allows Z. niveum to assimilate sufficient sulfide to sustain the symbiosis at a few micromoles per liter in ambient concentration. Numerical modeling shows that sulfide oxidizing bacteria on the surfaces of Z. niveum can sustain 100-times higher sulfide uptake than bacteria on flat surfaces, such as microbial mats. The study demonstrates that the filter feeding zooids of Z. niveum are preadapted to be prime habitats for sulfide oxidizing bacteria due to Z. niveum’s habitat preference and due to the feeding current. Z. niveum is capable of exploiting low concentrations of sulfide in near norm-oxic seawater. This links its otherwise dissimilar habitats and makes it functionally similar to invertebrates with thiotrophic symbionts in filtering organs.Electronic supplementary materialThe online version of this article (doi:10.1007/s00227-008-1117-6) contains supplementary material, which is available to authorized users.

A new freshwater peritrichous ciliate from Harbin, China, Epistylis lalinensis n. sp. (Sessilida: Epistylididae)

A freshwater peritrich ciliate, Epistylis lalinensis n. sp., was collected from Lalin River, Harbin, China, and its morphology, infraciliature and silverline system were investigated based on living and silver-impregnated specimens. The new species measured 125-187 × 31-47 μ m in vivo and is characterized by having green-coloured endoplasm containing symbiotic algae, single apically located contractile vacuole, one-layer peristomial collar and slender body shape. The Cshaped macronucleus is transversely located. Three equally kineties in polykinety 3 parallel to each other. Number of silverlines between peristome and aboral trochal band, 117-145; between aboral trochal band and scopula, 50-68. Comparing most other congeners, circular fibers of this species composed of internal and external layers.

Occurrence of peritrich ciliates on the limnic oligochaete Limnodrilus hoffmeisteri (Oligochaeta, Tubificidae) in the neotropics

Site preference and spatial and temporal occurrence of the peritrich ciliate Rhabdostyla sp. colonizing oligochaetes of the species Limnodrilus hoffmeisteri were investigated along a polluted stream in Brazil. Three patterns of site preference of the ciliates on the oligochaetes were observed, with the location of Rhabdostyla sp. predominantly on the posterior region of L. hoffmeisteri. The occurrence of the epibionts on the oligochaetes was spatially and temporally heterogeneous. The results are discussed in terms of the possible causes of the ciliates' preference for the posterior region of the tubificids, and the factors related to the heterogeneous spatial and temporal patterns.

Attachment of the peritrich epibiont Zoothamnium intermedium Precht, 1935 (Ciliophora, Peritrichia) to artificial substrates in a natural environment

Peritrich ciliates are commonly found as epibionts, colonizing living organisms, or attached to non-living substrates in freshwater, estuarine and marine environments. Several species of peritrich epibionts are obligate, which means that they are able to only colonize other organisms, while others are facultative attaching to living or non-living substrates. The peritrich Zoothamnium intermedium is commonly found as epibiont on the copepod species Acartia tonsa and Eurytemora affinis in Chesapeake Bay, USA. Previous studies demonstrated that Z. intermedium is not able to attach to non-living substrates in the laboratory; with free-swimming stages (telotrochs) dying when living substrates are not available for colonization. The present study investigated the ability of Z. intermdium to colonize artificial substrates in the field. Observations were carried out while the peritrich ciliate was colonizing copepods in Rhode River, a tributary of Chesapeake Bay. Results demonstrated that four species of Zoothamnium were recovered from artificial substrates, but none of them was Z. intermedium. At the same time, Z. intermedium was colonizing adults and copepodites of E. affinis and A. tonsa during the whole study period. These results, in addition to laboratory observations, suggest that Z. intermedium is an obligate epibiont.

A description of Apocarchesium rosettum n. gen., n. sp. and a redescription of Ophrydium eichornii , two freshwater peritrichous ciliates from Japan

This paper includes the proposal of a new genus for a new species of peritrichous ciliate, Apocarchesium rosettum n. gen., n. sp., as well as the first description by modern techniques of another peritrich, Ophrydium eichornii Ehrenberg, 1838. The genus Apocarchesium is separated from the related genus Carchesium by the appearance of the stalk and the arrangement of zooids, and diagnosed as follows: colonial vorticellid, with all zooids attached in rosette fashion to the tip of their common stalk, which is unbranched and contracts spirally; pellicle with parallel silverlines. The morphology, infraciliature, and silverline system of both species were investigated by observation in vivo and silver-staining methods.

Reconsideration of the Phylogenetic Positions of Five Peritrich Genera, Vorticella, Pseudovorticella, Zoothamnopsis, Zoothamnium, and Epicarchesium (Ciliophora, Peritrichia, Sessilida), Based on Small Subunit rRNA Gene Sequences

In order to re-evaluate the systematics of sessilid peritrich ciliates, small subunit (SSU) rRNA gene sequences were determined for 12 species belonging to five genera: Vorticella, Pseudovorticella, Epicarchesium, Zoothamnium, and Zoothamnopsis. Phylogenetic trees were deduced using Bayesian inference, maximum parsimony, and maximum likelihood methods. The phylogenetic analyses suggest that (1) sessilids which have stalks with continuous myonemes that contract in a zig-zag fashion form a separate clade from those which have stalks that contract independently and in a spiral fashion, supporting the separation of the family Zoothamniidae from the family Vorticellidae and (2) Epicarchesium and Pseudovorticella, both of which have reticulate silverline systems, are more closely related to each other than to other vorticellids, suggesting that differences in the silverline system (i.e. transverse vs. reticulate) may be the result of genuine evolutionary divergence among sessilid peritrichs. However, the newly sequenced Zoothamnopsis sinica, which has a reticulate silverline pattern, nests within the unresolved Zoothamnium species that have transverse silverline patterns. Thus, there were at least two evolutions of the reticulate silverline pattern character state from a plesiomorphic transverse state in the peritrichid ciliates. The molecular work demonstrates the genus Zoothamnium to be paraphyletic in relation to morphological studies, and suggests that Astylozoon, Opisthonecta, and Vorticella microstoma possibly share a SSU rRNA secondary structure in the helix E10-1 region.

Telotroch formation, survival, and attachment in the epibiotic peritrich Zoothamnium intermedium (Ciliophora, Oligohymenophorea)

Abstract. Aspects of the life cycle of the peritrich ciliate Zoothamnium intermedium, an epibiont on calanoid copepods in the Chesapeake Bay, were investigated using host and epibiont cultures. Experiments were designed to characterize the formation, survival, and attachment of free‐swimming stages (telotrochs) and to assess whether telotrochs preferentially attach to primary (Acartia tonsa and Eurytemora affinis) or alternate hosts from the zooplankton community (the rotifer Brachionus plicatilis, barnacle nauplii, polychaete larvae, and a harpacticoid copepod). The results showed that telotroch formation started 2 h after the death of the host, with >90% of the zooids leaving the host carapace within 7 h. Formation of telotrochs was triggered only by the death of the host, failing to occur when the host was injured or unable to swim. Telotrochs failed to attach to non‐living substrates and survived for only 14 h in the absence of host organisms, suggesting that members of Z. intermedium are obligate epibionts. Attachment success decreased with telotroch age, indicating that colonization success in nature may strongly depend on the ability to find a suitable host in a short period of time. Individuals exhibited no preferences in colonizing juvenile or adult stages of A. tonsa or E. affinis. While telotrochs were able to colonize barnacle nauplii and the harpacticoid copepod in the absence of individuals of A. tonsa or E. affinis, they did not attach to the rotifers or polychaete larvae. Telotrochs preferentially colonized individuals of A. tonsa when in the presence of other non‐calanoid host species.

Growth of the peritrich epibiont Zoothamnium intermedium Precht, 1935 (Ciliophora, Peritrichia) estimated from laboratory experiments

Peritrich ciliates are commonly found colonizing living substrates. Although this a well known phenomenon, biological aspects of this relationship need to be studied in more detail. Assessment of growth rates in peritrichs has been the subject of very few studies. Only species in the genera Carchesium Ehrenberg, 1830 and Vorticella Linnaeus, 1767 had their growth rates evaluated in the field and in the laboratory. In the present study, growth, colonization (colonies/host), and proliferation (zooids/colony) rates of the peritrich epibiont Zoothamnium intermedium Precht, 1935 attached to the calanoid copepod Acartia tonsa Dana 1848 were evaluated in the laboratory in two food regimes: bacteria only, and algal based diet. Results showed that growth, colonization, and proliferation rates were similar for both diets. Maximum growth rates obtained for Z. intermedium was 0.85 and 0.83 per day, for bacteria and algae respectively. Maximum colonization rates were 0.5 per day for both diets, and the maximum proliferation rates were 0.44 and 0.42 per day for bacteria and algae respectively. These results demonstrate that Z. intermedium is able to grow at the same rate of other peritrichs on bacterial and algal based diets.

Classification of the peritrich ciliate Opisthonecta matiensis (Martín-Cereceda et al. 1999) as Telotrochidium matiense nov. comb., based on new observations and SSU rDNA phylogeny

New observations on Opisthonecta matiensis Martín-Cereceda et al. [1999. Description of Opisthonecta matiensis n. sp. (Protozoa, Ciliophora), a new peritrich ciliate from wastewater. J. Eukaryot. Microbiol. 46, 283–289] especially the lack of an epistomial membrane, reveal that the species does not belong to the genus Opisthonecta, but to Telotrochidium, the other genus within the family Opisthonectidae Foissner, 1975. The contractile vacuole and the cytopyge are on the dorsal wall of the vestibulum and the trochal band is limited distally and proximally by rows of narrowly spaced pellicular pores. Thus the species is redefined as Telotrochidium matiense nov. comb. The morphological, cortical and nuclear events occurring during conjugation are illustrated, compared with those in other species, and phylogenetically discussed. Invariably, the microconjugants attach to and penetrate the lateral side of the macroconjugants. Nuclear processes are very similar to those reported from other peritrichs. The small subunit rRNA gene (SSU rDNA) is sequenced and the phylogeny within Opisthonectidae and peritrichs examined. T. matiense is more closely related to Epistylis (63% Maximum Parsimony (MP), 85% Maximum Likelihood (ML)) than to any other genus, while another representative of the family, viz., Opisthonecta henneguyi, is closely related to Vorticella microstoma, Astylozoon enriquesi and clone RT3n18 (100% MP, 100% ML). Morphology and gene sequences suggest that Telotrochidium and Opisthonecta have derived from different lineages of stalked peritrichs: Opisthonecta could have arisen from peritrichs with stalk myonemes, while Telotrochidium probably evolved from peritrichs without stalk myonemes.

Molecular Phylogenetics of Subclass Peritrichia (Ciliophora: Oligohymenophorea) Based on Expanded Analyses of 18S rRNA Sequences

Phylogenetic relationships among peritrich ciliates remain unclear in spite of recent progress. To expand the analyses performed in previous studies, and to statistically test hypotheses of monophyly, we analyzed a broad sample of 18s rRNA sequences (including 15 peritrich genera), applying a conservative alignment strategy and several phylogenetic approaches. The main results are that: (i) the monophyly of Peritrichia cannot be rejected; (ii) the two main clades of Sessilida do not correspond to formally recognized taxa; (iii) the monophyly of genera Vorticella and Epistylis is significantly rejected; and (iv) morphological structures commonly used in peritrich taxonomy may be evolutionarily labile.

Detrimental effect of peritrich ciliates (Epistylis sp.) as epibionts on the survival of the copepod Acartia bifilosa

Detrimental effect of peritrich ciliates (Epistylis sp.) as epibionts on the survival of the copepod Acartia bifilosa

Pseudovorticella zhengae n. sp., P. difficilis (Kahl, 1933) Jankowski, 1976, and P. punctata (Dons, 1918) Warren, 1987, three marine peritrichous ciliates from north China

The morphology, infraciliature and silverline system of three marine peritrichous ciliates, Pseudovorticella zhengae n. sp., P. difficilis (Kahl, 1933) Jankowski, 1976 and P. punctata (Dons, 1918) Warren, 1987, were investigated by observation in vivo and silver-staining methods. The new species is characterized by its body shape, the appearance of the peristomial lip, the number of transverse silverlines, and the configuration of infundibular polykinety 3; P. difficilis by its body shape, the configuration of infundibular polykinety 3, and unusual annular swellings on the stalk; and P. punctata by the appearance of the pellicle, the configuration of infundibular polykinety 3, and the number of transverse silverlines.

Taxonomic characterization of two marine peritrichous ciliates, Epicarchesium corlissi n. sp. and Pseudovorticella jiangi n. sp. (Ciliophora: Peritrichia), from northern China

Two new marine peritrich ciliates, Epicarchesium corlissi n. sp. and Pseudovorticella jiangi n. sp., were discovered in mariculture waters on the coast of northern China near Qingdao. Their morphology, infraciliature and silverline system were investigated based on both living and silver-impregnated specimens. E. corlissi is characterized as follows: marine Epicarchesium with dichotomously branched stalk; zooids elongate, approximately 60–70×25–35 μm in vivo; peristomial collar double-folded; macronucleus J-shaped; single, small contractile vacuole ventrally positioned; more than 60 striations between peristome and aboral trochal band, 13–18 from aboral trochal band to scopula; abstomal end of row 1 of infundibular polykinety 3 terminating at same level as rows 2 and 3 of infundibular polykinety 3; rows 2 and 3 of infundibular polykinety 3 much longer than row 1 and converging adstomally with infundibular polykinety 1. The new species P. jiangi is diagnosed as follows: marine Pseudovorticella; zooid inverted bell-shaped, approximately 80×60 μm in vivo and with a broad, flat, thin peristomial collar that measures approximately 90 μm across; pellicle with transparent cortical vesicles; macronucleus J-shaped; number of silverlines between peristome and aboral trochal band 20–24, from aboral trochal band to scopula 9–11; abstomal end of row 1 of infundibular polykinety 3 diverges from the other two rows of this polykinety and ends alongside row 3 of infundibular polykinety 2.

The effect of peritrich ciliates on some freshwater leeches from Assiut, Egypt

During October 2004 to April 2005, when water temperature ranged between 18 and 22 °C, over than 500 specimens of leeches namely Alboglossiphonia polypompholyx, Batracobdelloides tricarinata, Helobdella conifera (Rhynchobdellida), Barbronia assiuti, and Salifa delicata (Arhynchobdellida) were collected from Al-Sont canal near Assiut city. About 80% of these specimens were infected with the peritrich ciliate Epistylis sp. The infection occurred in the field, both rhynchobdellid and arhynchobdellid leeches were infected, but Epistylis can infect rhynchobdellids more than arhynchobdellids. Both light and scanning electron microscopy showed the morphology of this parasite which attached to the surface of the leech body by a stalk. Histopathological studies revealed the damage of cuticle, epidermis, and dermis of the leech body wall at the area of attachment and the leech body seemed to be sloughy. Presence of this parasite in high numbers covering large areas of the body can impede gas exchange leading to leech suffocation and finally its death. Like the other sessile single-celled ciliates Epistylis spp. feed on bacteria and suspended organic debris, which are prevalent in nutrient-rich water, hence, Epistylis is a good indicator of poor water quality (pollution). The present study represents the first report of the effect of Epistylis on leeches collected from Egypt.

Reevaluation of the Phylogenetic Relationship between Mobilid and Sessilid Peritrichs (Ciliophora, Oligohymenophorea) Based on Small Subunit rRNA Genes Sequences

Based on morphological characters, peritrich ciliates (Class Olygohymenophorea, Subclass Peritrichia) have been subdivided into the Orders Sessilida and Mobilida. Molecular phylogenetic studies on peritrichs have been restricted to members of the Order Sessilida. In order to shed more light into the evolutionary relationships within peritrichs, the complete small subunit rRNA (SSU rRNA) sequences of four mobilid species, Trichodina nobilis, Trichodina heterodentata, Trichodina reticulata, and Trichodinella myakkae were used to construct phylogenetic trees using maximum parsimony, neighbor joining, and Bayesian analyses. Whatever phylogenetic method used, the peritrichs did not constitute a monophyletic group: mobilid and sessilid species did not cluster together. Similarity in morphology but difference in molecular data led us to suggest that the oral structures of peritrichs are the result of evolutionary convergence. In addition, Trichodina reticulata, a Trichodina species with granules in the center of the adhesive disc, branched separately from its congeners, Trichodina nobilis and Trichodina heterodentata, trichodinids without such granules. This indicates that granules in the adhesive disc might be a phylogenetic character of high importance within the Family Trichodinidae.

Taxonomic Characterization of Vorticella fuscaPrecht, 1935 and Vorticella parapulchella n. sp., Two Marine Peritrichs (Ciliophora, Oligohymenophorea) from China

Two marine peritrich ciliates, Vorticella fuscaPrecht (1935) and Vorticella parapulchella n. sp. were discovered in the littoral zone of Qingdao, northern China. Their morphology, infraciliature, and silverline system were described using live observation and silver impregnation. The poorly known species V. fusca is redescribed, adding information about the oral infraciliature and pellicular morphology. Vorticella parapulchella n. sp. is superficially similar to Vorticella pulchellaSommer (1951) but is distinguished from it by being markedly smaller and having much more widely spaced pellicular ridges. The infundibular infraciliature of V. parapulchella is extremely unusual in having infundibular polykinety 3 reduced to two rows, one of which has almost disappeared.

Protozoan Epibionts and Their Distribution on the Arctic Ice-amphipod Gammarus wilkitzkii from Spitsbergen, Norway

Specimens of the Arctic sympagic amphipod Gammarus wilkitzkii, which were collected in the ice-covered areas near Spitsbergen, Norway, were infested with protozoan epibionts in densities of 499 to 3346 individuals per amphipod. The epibionts belong to the five ciliate genera: Ephelota, Cryptacineta, Acineta and Podophrya (suctorian ciliates), and Epistylis (peritrich ciliate). In this study we present the first observations of epibionts on ice-associated crustaceans and provide a detailed description of morphological and taxonomical aspects of the different ciliate genera. Cryptacineta has not been found earlier in the marine environment. This ciliate showed the highest density values (215–2571 individuals per amphipod), followed by Ephelota (2–1302 ind./amphipod). The number of individuals of Acineta, Podophrya, and Epistylis did not surpass 240 ind./amphipod. Epibionts colonized all appendages and the entire body surface, but were most numerous on the anterior body part of G. wilkitzkii. The body length of the gammarid and the number of epibionts of Ephelota, Podophrya, and Epistylis were positively correlated. The highest density of epibionts was found on the anterior body parts with the antennae bearing up to 613 individuals. In contrast, the posterior body showed only little burden. The number of epibionts along the caput-telson axis of the amphipod body shows a decrease towards the posterior end of the amphipod. The highest degree of infestation was found on females, followed by juveniles and eventually, males. When grouping the 37 anatomical units (including left and right appendages) to 8 body “regions,” the pereiopods, as a whole, showed the highest density (39.25%), followed by the gnathopods (22.29%), and antennulae and antennae. Basibiont got infested with the sessile ciliates in the benthic and pelagic environment during the ice-free season and carried them along back to the sympagic ecosystem when colonizing the newly formed ice. Epibionts are therefore considered as indicators for bentho-sympagic coupling processes.

Population Genetic Structure of Carchesium polypinum (Ciliophora: Peritrichia) in Four Chinese Lakes Inferred from ISSR Fingerprinting: High Diversity but Low Differentiation

Although the peritrichous ciliate Carchesium polypinum is common in freshwater, its population genetic structure is largely unknown. We used inter-simple sequence repeat (ISSR) fingerprinting to analyze the genetic structure of 48 different isolates of the species from four lakes in Wuhan, central China. Using eight polymorphic primers, 81 discernible DNA fragments were detected, among which 76 (93.83%) were polymorphic, indicating high genetic diversity at the isolate level. Further, Nei's gene diversity (h) and Shannon's Information index (I) between the different isolates both revealed a remarkable genetic diversity, higher than previously indicated by their morphology. At the same time, substantial gene flow was found. So the main factors responsible for the high level of diversity within populations are probably due to conjugation (sexual reproduction) and wide distribution of swarmers. Analysis of molecular variance (AMOVA) showed that there was low genetic differentiation among the four populations probably due to common ancestry and flooding events. The cluster analysis and principal component analysis (PCA) suggested that genotypes isolated from the same lake displayed a higher genetic similarity than those from different lakes. Both analyses separated C. polypinum isolates into subgroups according to the geographical locations. However, there is only a weak positive correlation between the genetic distance and geographical distance, suggesting a minor effect of geographical distance on the distribution of genetic diversity between populations of C. polypinum at the local level. In conclusion, our studies clearly demonstrated that a single morphospecies may harbor high levels of genetic diversity, and that the degree of resolution offered by morphology as a marker for measuring distribution patterns of genetically distinct entities is too low.

The pink shrimp Farfantepenaeus duorarum, its symbionts and helminths as bioindicators of chemical pollution in Campeche Sound, Mexico

The pink shrimp Farfantepenaeus duorarum may acquire pollutants, helminths and symbionts from their environment. Statistical associations were studied between the symbionts and helminths of F. duorarum and pollutants in sediments, water and shrimps in Campeche Sound, Mexico. The study area spatially overlapped between offshore oil platforms and natural shrimp mating grounds. Spatial autocorrelation of data was controlled with spatial analysis using distance indices (SADIE) which identifies parasite or pollutant patches (high levels) and gaps (low levels), expressing them as clustering indices compared at each point to produce a measure of spatial association. Symbionts included the peritrich ciliates Epistylis sp. and Zoothamnium penaei and all symbionts were pooled. Helminths included Hysterothylacium sp., Opecoeloides fimbriatus, Prochristianella penaei and an unidentified cestode. Thirty-five pollutants were identified, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides and heavy metals. The PAHs (2-3 ring) in water, unresolved complex mixture (UCM), Ni and V in sediments, and Zn, Cr and heptachlor in shrimps were significantly clustered. The remaining pollutants were randomly distributed in the study area. Juvenile shrimps acquired pesticides, PAHs (2-3 rings) and Zn, while adults acquired PAHs (4-5 rings), Cu and V. Results suggest natural PAH spillovers, and continental runoff of dichlorodiphenyltrichloroethane (DDT), PCBs and PAHs (2-3 ring). There were no significant associations between pollutants and helminths. However, there were significant negative associations of pesticides, UCM and PCBs with symbiont numbers after controlling shrimp size and spatial autocorrelation. Shrimps and their symbionts appear to be promising bioindicators of organic chemical pollution in Campeche Sound.