To see the other types of publications on this topic, follow the link: Ciliats.
Journal articles on the topic 'Ciliats'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Ciliats.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
IGLESIAS, R., A. PARAMÁ, M. F. ÁLVAREZ, J. LEIRO, F. M. UBEIRA, and M. L. SANMARTÍN. "Philasterides dicentrarchi (Ciliophora: Scuticociliatida) expresses surface immobilization antigens that probably induce protective immune responses in turbot." Parasitology 126, no. 2 (February 2003): 125–34. http://dx.doi.org/10.1017/s0031182002002688.
Full textAbstract:
Philasterides dicentrarchi is a histophagous ciliate causing systemic scuticociliatosis in cultured turbot. This study demonstrates that turbot which survive this disease have serum antibodies that recognize ciliary antigens of this ciliate in ELISA and immobilize/agglutinate the ciliate in vitro. Mouse sera raised against ciliary antigens and integral membrane proteins are likewise capable of immobilizing/agglutinating the ciliates, indicating that P. dicentrarchi, like other ciliates, expresses surface immobilization antigens. Furthermore, the antigen agglutinating reaction induces the parasite to shed its surface antigens rapidly, replacing them with others with different specific serology. This antigen shedding and variation response is similar to that detected in other protozoan parasites. Immunization of turbot with ciliate lysate plus adjuvant or with formalin-fixed ciliates induced synthesis of agglutinating antibodies and conferred a degree of protection against challenge infection, suggesting that the response to surface antigens may play an important role in defence against this pathogen, SDS–PAGE and immunoblotting studies indicated the existence of a predominant polypeptide of about 38 kDa in the ciliary antigen and membrane protein fractions, and this may be the principal surface antigen of P. dicentrarchi.
2
Ohmura, Takuya, Yukinori Nishigami, Atsushi Taniguchi, Shigenori Nonaka, Junichi Manabe, Takuji Ishikawa, and Masatoshi Ichikawa. "Simple mechanosense and response of cilia motion reveal the intrinsic habits of ciliates." Proceedings of the National Academy of Sciences 115, no. 13 (March 12, 2018): 3231–36. http://dx.doi.org/10.1073/pnas.1718294115.
Full textAbstract:
An important habit of ciliates, namely, their behavioral preference for walls, is revealed through experiments and hydrodynamic simulations. A simple mechanical response of individual ciliary beating (i.e., the beating is stalled by the cilium contacting a wall) can solely determine the sliding motion of the ciliate along the wall and result in a wall-preferring behavior. Considering ciliate ethology, this mechanosensing system is likely an advantage in the single cell’s ability to locate nutrition. In other words, ciliates can skillfully use both the sliding motion to feed on a surface and the traveling motion in bulk water to locate new surfaces according to the single “swimming” mission.
3
Ishikawa, Takuji, Tomoyuki Tanaka, Yohsuke Imai, Toshihiro Omori, and Daiki Matsunaga. "Deformation of a micro-torque swimmer." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2185 (January 2016): 20150604. http://dx.doi.org/10.1098/rspa.2015.0604.
Full textAbstract:
The membrane tension of some kinds of ciliates has been suggested to regulate upward and downward swimming velocities under gravity. Despite its biological importance, deformation and membrane tension of a ciliate have not been clarified fully. In this study, we numerically investigated the deformation of a ciliate swimming freely in a fluid otherwise at rest. The cell body was modelled as a capsule with a hyperelastic membrane enclosing a Newtonian fluid. Thrust forces due to the ciliary beat were modelled as torques distributed above the cell body. The effects of membrane elasticity, the aspect ratio of the cell's reference shape, and the density difference between the cell and the surrounding fluid were investigated. The results showed that the cell deformed like a heart shape, when the capillary number was sufficiently large. Under the influence of gravity, the membrane tension at the anterior end decreased in the upward swimming while it increased in the downward swimming. Moreover, gravity-induced deformation caused the cells to move gravitationally downwards or upwards, which resulted in a positive or negative geotaxis-like behaviour with a physical origin. These results are important in understanding the physiology of a ciliate's biological responses to mechanical stimuli.
4
Wan, Kirsty Y., Sylvia K. Hürlimann, Aidan M. Fenix, Rebecca M. McGillivary, Tatyana Makushok, Evan Burns, Janet Y. Sheung, and Wallace F. Marshall. "Reorganization of complex ciliary flows around regenerating Stentor coeruleus." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1792 (December 30, 2019): 20190167. http://dx.doi.org/10.1098/rstb.2019.0167.
Full textAbstract:
The phenomenon of ciliary coordination has garnered increasing attention in recent decades and multiple theories have been proposed to explain its occurrence in different biological systems. While hydrodynamic interactions are thought to dictate the large-scale coordinated activity of epithelial cilia for fluid transport, it is rather basal coupling that accounts for synchronous swimming gaits in model microeukaryotes such as Chlamydomonas. Unicellular ciliates present a fascinating yet understudied context in which coordination is found to persist in ciliary arrays positioned across millimetre scales on the same cell. Here, we focus on the ciliate Stentor coeruleus , chosen for its large size, complex ciliary organization, and capacity for cellular regeneration. These large protists exhibit ciliary differentiation between cortical rows of short body cilia used for swimming, and an anterior ring of longer, fused cilia called the membranellar band (MB). The oral cilia in the MB beat metachronously to produce strong feeding currents. Remarkably, upon injury, the MB can be shed and regenerated de novo. Here, we follow and track this developmental sequence in its entirety to elucidate the emergence of coordinated ciliary beating: from band formation, elongation, curling and final migration towards the cell anterior. We reveal a complex interplay between hydrodynamics and ciliary restructuring in Stentor , and highlight for the first time the importance of a ring-like topology for achieving long-range metachronism in ciliated structures. This article is part of the Theo Murphy meeting issue ‘Unity and diversity of cilia in locomotion and transport’.
5
ELLOUMI, J., Z. DRIRA, A. HAMZA, and H. AYADI. "Space-time variation of ciliates related to environmental factors in 15 nearshore stations of the Gulf of Gabes." Mediterranean Marine Science 16, no. 1 (July 22, 2014): 162. http://dx.doi.org/10.12681/mms.792.
Full textAbstract:
Diversity and structure of ciliate communities in the Gulf of Gabes (Tunisia) were investigated based on a survey of 15 nearshore stations along 237 Km, by monthly sampling over a 1-year. Ciliated protozoa were identified to genus and/or species level and enumerated. Statistic tools were used to explain the ciliates assemblage. High ciliates species richness from 133 taxa was recorded, including new records of 76 species. This study showed a longitudinal distribution of ciliate communities, which are organized in northern stations (from Tabia to Harbor of Gabes) and southern stations (from Zarrat to Jabiat Haj Ali). The number of taxa increased significantly in northern stations but decreased in the southern. This distribution was mainly influenced by the salinity and phytoplankton abundance. Ciliate taxa were grouped into fives size-classes: 15-30 µm, 30-50 µm, 50-100 µm, 100-200 µm and >200 µm. In terms of abundance, most abundant size groups were small ciliates (15-30 μm) accounted from 15 to 79 %, while the greatest biomass contribution came from the 50-100 μm size classes. We thus conclude high diversity of ciliates communities that showed a geographical distribution influenced by abiotic and biotic factors along the coast of Gulf of Gabes.
6
Decamp, O., A. Warren, and R. Sanchez. "The Role of Ciliated Protozoa in Subsurface Flow Wetlands and their Potential as Bioindicators." Water Science and Technology 40, no. 3 (August 1, 1999): 91–98. http://dx.doi.org/10.2166/wst.1999.0143.
Full textAbstract:
The role of ciliated protozoa in the root zone method of wastewater treatment was assessed by analyzing ciliate community structure in four experimental subsurface flow wetlands (planted or unplanted in either soil or gravel) and estimating Escherichia coli removal due to ciliate predation. A total of 22 different ciliate taxa were isolated from the four reed beds. The first third of each bed contained a higher abundance and diversity than the final third of the bed. There was a qualitative correlation between physicochemical conditions and ciliate community structure: microaerophilic species dominated the organic-rich and oxygen-poor environment of the unplanted soil bed; aerobic and facultative bacterivorous species dominated the better oxygenated gravel beds; a combination of these two communities was found in the planted soil bed. The average grazing rates of ciliates was around 5 times higher in the planted gravel bed (49 bacteria/ciliate/hour) than in the unplanted soil bed (9.5 bacteria/ciliate/hour). Taking into account the retention time and ciliate abundance, it was calculated that ciliates, by their predatory activities, are capable of removing up to 2.35 × 105 and 0.45 × 105E. coli in the first third of the planted gravel bed and unplanted soil bed, respectively. These results are discussed in relation to variation in E. coli removal kinetics. The potential for using ciliate communities as indicators of conditions within constructed wetlands is also assessed.
7
Mutazono, Masatoshi, Tomoko Noto, and Kazufumi Mochizuki. "Diversification of small RNA amplification mechanisms for targeting transposon-related sequences in ciliates." Proceedings of the National Academy of Sciences 116, no. 29 (July 1, 2019): 14639–44. http://dx.doi.org/10.1073/pnas.1903491116.
Full textAbstract:
The silencing of repetitive transposable elements (TEs) is ensured by signal amplification of the initial small RNA trigger, which occurs at distinct steps of TE silencing in different eukaryotes. How such a variety of secondary small RNA biogenesis mechanisms has evolved has not been thoroughly elucidated. Ciliated protozoa perform small RNA-directed programmed DNA elimination of thousands of TE-related internal eliminated sequences (IESs) in the newly developed somatic nucleus. In the ciliate Paramecium, secondary small RNAs are produced after the excision of IESs. In this study, we show that in another ciliate, Tetrahymena, secondary small RNAs accumulate at least a few hours before their derived IESs are excised. We also demonstrate that DNA excision is dispensable for their biogenesis in this ciliate. Therefore, unlike in Paramecium, small RNA amplification occurs before IES excision in Tetrahymena. This study reveals the remarkable diversity of secondary small RNA biogenesis mechanisms, even among ciliates with similar DNA elimination processes, and thus raises the possibility that the evolution of TE-targeting small RNA amplification can be traced by investigating the DNA elimination mechanisms of ciliates.
8
Ito, Hiroaki, Toshihiro Omori, and Takuji Ishikawa. "Swimming mediated by ciliary beating: comparison with a squirmer model." Journal of Fluid Mechanics 874 (July 12, 2019): 774–96. http://dx.doi.org/10.1017/jfm.2019.490.
Full textAbstract:
The squirmer model of Lighthill and Blake has been widely used to analyse swimming ciliates. However, real ciliates are covered by hair-like organelles, called cilia; the differences between the squirmer model and real ciliates remain unclear. Here, we developed a ciliate model incorporating the distinct ciliary apparatus, and analysed motion using a boundary element–slender-body coupling method. This methodology allows us to accurately calculate hydrodynamic interactions between cilia and the cell body under free-swimming conditions. Results showed that an antiplectic metachronal wave was optimal in the swimming speed with various cell-body aspect ratios, which is consistent with former theoretical studies. Exploiting oblique wave propagation, we reproduced a helical trajectory, like Paramecium, although the cell body was spherical. We confirmed that the swimming velocity of model ciliates was well represented by the squirmer model. However, squirmer modelling outside the envelope failed to estimate the energy costs of swimming; over 90 % of energy was dissipated inside the ciliary envelope. The optimal swimming efficiency was given by the antiplectic wave; the value was 6.7 times larger than in-phase beating. Our findings provide a fundamental basis for modelling swimming micro-organisms.
9
Jiang, Yong, Wei Zhang, Mingzhuang Zhu, Khaled A. S. Al-Rasheid, and Henglong Xu. "Are non-loricate ciliates a primary contributor to ecological pattern of planktonic ciliate communities? A case study in Jiaozhou Bay, northern China." Journal of the Marine Biological Association of the United Kingdom 92, no. 6 (March 28, 2012): 1301–8. http://dx.doi.org/10.1017/s0025315412000276.
Full textAbstract:
The contribution of non-loricate ciliate assemblage to the ecological pattern of a ciliated protozoan community was studied based on a 1-year (June 2007–May 2008) dataset collected from Jiaozhou Bay, northern China. Samples were collected biweekly from five sampling sites. Results showed that: (1) the non-loricate ciliate assemblages were the primary components and significantly correlated with the total ciliate communities in terms of species number, abundance and biomass; (2) the ecological pattern of non-loricate ciliate assemblages was significantly related to that of both total ciliate communities and variations in environmental variables; and (3) spatio-temporal variations in biodiversity (richness, diversity and evenness of species) indices of non-loricate ciliate assemblages were significantly correlated with those of total ciliate communities and the environmental conditions, especially nutrients nitrate nitrogen, nitrite nitrogen and soluble reactive phosphorous. These results suggest that the non-loricate ciliates are a primary contributor to the ecological pattern of total ciliate communities and might be used as a potential bioindicator for bioassessment in marine ecosystems.
10
GÜRELLİ, GÖZDE, and ASEM RAMADAN AMAR MOHAMED. "Ciliated Protozoan Fauna in the Forestomach of Dromedary Camels (Camelus dromedarius) in Libya." Zootaxa 4434, no. 3 (June 18, 2018): 429. http://dx.doi.org/10.11646/zootaxa.4434.3.2.
Full textAbstract:
Species composition and distribution of ciliated protozoa obtained from the forestomach of 20 dromedary camels living in Zawiya, Libya were examined. Nineteen species and 10 morphotypes belonging to eight genera were identified. The mean number of ciliates was 54.2 ± 32.9 × 104 cells ml−1 in the forestomach contents, and the mean number of ciliate species per host was 6.5 ± 2.9. Entodinium and Epidinium were the main genera, as these ciliates were found consistently at higher proportions than those of the other genera. In contrast, Ophryoscolex and Polyplastron were only observed at low frequencies. Diplodinium rangiferi, Entodinium ellipsoideum, E. simulans, and Polyplastron multivesiculatum were new endosymbionts recorded from camels.
11
Pinheiro, Marcel D. O., Mary E. Power, Barb J. Butler, Vivian R. Dayeh, Robin Slawson, Lucy E. J. Lee, Denis H. Lynn, and Niels C. Bols. "Inactivation of the Bacteriophage MS2 by the Ciliated Protozoan, Tetrahymena thermophila." Water Quality Research Journal 43, no. 1 (February 1, 2008): 69–76. http://dx.doi.org/10.2166/wqrj.2008.009.
Full textAbstract:
Abstract Because the range of biological mechanisms responsible for the inactivation of viruses in man-made and natural water systems is poorly understood, the involvement of the free-living ciliated protozoan, Tetrahymena thermophila, in viral inactivation was investigated. The ciliate was found to remove the bacteriophage MS2 when the phage and ciliate were co-incubated in a simple salt solution. MS2 was enumerated as plaque forming units (pfus). MS2 removal was achieved only by living and not formalin-fixed ciliates, and was blocked by treatments that impaired the formation of food vacuoles. These treatments were cytochalasin B and low temperature. When fluorescently labelled with SYBR gold prior to co-incubation, MS2 were seen inside Tetrahymena within vesicles that had the shape and size of food vacuoles. The number of pfus associated with Tetrahymena was low. This suggests that the engulfment of the phage into food vacuoles led to the inactivation of MS2, which is frequently used as a surrogate for poliovirus in environmental microbiology. In the future, a broader understanding of the capacity of ciliates to inactivate viruses could lead to methods for improving water quality through the manipulation of ciliate populations and activities.
12
CEDROLA, FRANCIANE, ROBERTO JÚNIO PEDROSO DIAS, ISABEL MARTINELE, and MARTA D’AGOSTO. "Description of Diploplastron dehorityi sp. nov. (Entodiniomorphida, Ophryoscolecidae), a new rumen ciliate from Brazilian sheep (Ovis aries)." Zootaxa 4258, no. 6 (May 3, 2017): 581. http://dx.doi.org/10.11646/zootaxa.4258.6.8.
Full textAbstract:
To date the genus Diploplastron comprised only one species of ophryoscolecid ciliate, Diploplastron affine, which is characterized by having two retractable ciliary zones in the anterior end of the body, two slender and juxtaposed skeletal plates on the right side, a rod shape macronucleus, and two contractile vacuoles. During study on the characterization of rumen ciliate community composition in Brazilian domestic sheep, we observed ciliates with atypical morphology but with diagnostic features of genus Diploplastron. This study describes Diploplastron dehorityi, a new species of ophryoscolecid ciliate, that differs from D. affine, primarily, in the morphology of skeletal plates, morphology of nuclear apparatus and body shape. In addition to the similarities between the new species and congener species, D. dehorityi has some morphological similarities to species of genus Eremoplastron.
13
Abraham, Jeeva Susan, S. Sripoorna, Swati Maurya, Seema Makhija, Renu Gupta, and Ravi Toteja. "Techniques and tools for species identification in ciliates: a review." International Journal of Systematic and Evolutionary Microbiology 69, no. 4 (April 1, 2019): 877–94. http://dx.doi.org/10.1099/ijsem.0.003176.
Full textAbstract:
Ciliates are highly divergent unicellular eukaryotic organisms with nuclear dualism and a highly specialized ciliary pattern. They inhabit all biotopes and play crucial roles in regulating microbial food webs as they prey on bacteria, protists and even on microscopic animals. Nevertheless, subtle morphological differences and tiny sizes hinder proper species identification for many ciliates. In the present review, an attempt has been made to elaborate the various approaches used by modern day ciliate taxonomists for species identification. The different approaches involved in taxonomic characterization of ciliates such as classical (using live-cell observations, staining techniques, etc.), molecular (involving various marker genes) and statistical (delimitation of cryptic species) methods have been reviewed. Ecological and behavioural aspects in species identification have also been discussed. In present-day taxonomy, it is important to use a ‘total evidence’ approach in identifying ciliates, relying on both classical and molecular information whenever possible. This integrative approach will help in the mergence of classical methods with modern-day tools for comprehensive species description in future.
14
Machemer, H. "Mechanoelectrical transduction mediated through cilia in protists." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 190–91. http://dx.doi.org/10.1017/s0424820100142578.
Full textAbstract:
Unicellular organisms respond to a variety of stimuli, such as light, touch, or chemical action. A Paramecium cell, which meets an obstacle, reverses the swimming direction and eventually resumes forward locomotion in a new direction. It has been a plausible assumption that the cilia are receptors as well as effectors. This view gains support by analogy: ciliary structures exist in various metazoan tissue specialized for stimulus sensation. A previous elegant hypothesis assumed that a ciliary mechanoreceptor employs the ciliary motile machine in reverse in that bending of the axoneme can generate a chemical signal. Recent electrophysiological studies in ciliates have contributed to a re-assessment of the role of cilia in mechanotransduction. This lecture summarizes some experimental evidence as to how the sensory function is organized in a ciliated cell.
15
Xu, Yiwei, Zhuo Shen, Eleni Gentekaki, Jiahui Xu, and Zhenzhen Yi. "Comparative Transcriptome Analyses during the Vegetative Cell Cycle in the Mono-Cellular Organism Pseudokeronopsis erythrina (Alveolata, Ciliophora)." Microorganisms 8, no. 1 (January 12, 2020): 108. http://dx.doi.org/10.3390/microorganisms8010108.
Full textAbstract:
Studies focusing on molecular mechanisms of cell cycles have been lagging in unicellular eukaryotes compared to other groups. Ciliates, a group of unicellular eukaryotes, have complex cell division cycles characterized by multiple events. During their vegetative cell cycle, ciliates undergo macronuclear amitosis, micronuclear mitosis, stomatogenesis and somatic cortex morphogenesis, and cytokinesis. Herein, we used the hypotrich ciliate Pseudokeronopsis erythrina, whose morphogenesis has been well studied, to examine molecular mechanisms of ciliate vegetative cell cycles. Single-cell transcriptomes of the growth (G) and cell division (D) stages were compared. The results showed that (i) More than 2051 significantly differentially expressed genes (DEGs) were detected, among which 1545 were up-regulated, while 256 were down-regulated at the D stage. Of these, 11 randomly picked DEGs were validated by reverse transcription quantitative polymerase chain reaction (RT-qPCR); (ii) Enriched DEGs during the D stage of the vegetative cell cycle of P. erythrina were involved in development, cortex modifications, and several organelle-related biological processes, showing correspondence of molecular evidence to morphogenetic changes for the first time; (iii) Several individual components of molecular mechanisms of ciliate vegetative division, the sexual cell cycle and cellular regeneration overlap; and (iv) The P. erythrina cell cycle and division have the same essential components as other eukaryotes, including cyclin-dependent kinases (CDKs), cyclins, and genes closely related to cell proliferation, indicating the conserved nature of this biological process. Further studies are needed focusing on detailed inventory and gene interactions that regulate specific ciliated cell-phase events.
16
Stickle, William B., Eugene N. Kozloff, and Shana Story. "Physiology of the ciliate Orchitophrya stellarum and its experimental infection of Leptasterias spp." Canadian Journal of Zoology 85, no. 2 (February 2007): 201–6. http://dx.doi.org/10.1139/z06-211.
Full textAbstract:
Orchitophrya stellarum Cépède, 1907 is a facultative ciliate that parasitizes male asteriid sea stars in the North Atlantic and Pacific oceans. The ciliate also exists in seawater where it feeds on bacteria associated with tissue or yeast. This study is designed to determine the tolerance, growth rate, contractile vacuole activity, and infectivity to Leptasterias Verrill, 1866 spp. as a function of the sea star’s reproductive cycle stage. The tolerance range of O. stellarum in seawater containing bacteria is 2 practical salinity units (PSU) at 8 °C and 12.5 PSU at 25 °C; the ciliate tolerated a temperature range of 3–27 °C at 30 PSU. Ciliate population growth is most rapid at 24 °C and is minimal at 3 and 27 °C at 30 PSU. The ciliate’s contractile vacuole cycle frequency increases at low salinity, indicating increased water volume regulation as a function of decreased salinity. Unparasitized male Leptasterias spp. can be infected experimentally by injection of a culture of O. stellarum into the rays or from a culture in ambient seawater only when the testes are at full size, but the ciliates do not invade ovarian tissue. The normal path of entry of O. stellarum into the testes of reproductively mature male sea stars probably takes place through gonopores.
17
Hojo, Fuhito, Daisuke Sato, Junji Matsuo, Masaki Miyake, Shinji Nakamura, Miyuki Kunichika, Yasuhiro Hayashi, et al. "Ciliates Expel Environmental Legionella-Laden Pellets To Stockpile Food." Applied and Environmental Microbiology 78, no. 15 (May 25, 2012): 5247–57. http://dx.doi.org/10.1128/aem.00421-12.
Full textAbstract:
ABSTRACTWhenTetrahymenaciliates are cultured withLegionella pneumophila, the ciliates expel bacteria packaged in free spherical pellets. Why the ciliates expel these pellets remains unclear. Hence, we determined the optimal conditions for pellet expulsion and assessed whether pellet expulsion contributes to the maintenance of growth and the survival of ciliates. When incubated with environmentalL. pneumophila, the ciliates expelled the pellets maximally at 2 days after infection. Heat-killed bacteria failed to produce pellets from ciliates, and there was no obvious difference in pellet production among the ciliates or bacterial strains. Morphological studies assessing lipid accumulation showed that pellets contained tightly packed bacteria with rapid lipid accumulation and were composed of the layers of membranes; bacterial culturability in the pellets rapidly decreased, in contrast to what was seen in ciliate-free culture, although the bacteria maintained membrane integrity in the pellets. Furthermore, ciliates newly cultured with pellets were maintained and grew vigorously compared with those without pellets. In contrast, a humanL. pneumophilaisolate killed ciliates 7 days postinfection in a Dot/Icm-dependent manner, and pellets harboring this strain did not support ciliate growth. Also, pellets harboring the human isolate were resuscitated by coculturing with amoebae, depending on Dot/Icm expression. Thus, while ciliates expel pellet-packaged environmentalL. pneumophilafor stockpiling food, the pellets packaging the human isolate are harmful to ciliate survival, which may be of clinical significance.
18
Stott, R., E. May, E. Matsushita, and A. Warren. "Protozoan predation as a mechanism for the removal of cryptosporidium oocysts from wastewaters in constructed wetlands." Water Science and Technology 44, no. 11-12 (December 1, 2001): 191–98. http://dx.doi.org/10.2166/wst.2001.0828.
Full textAbstract:
The removal of the protozoan parasite, Cryptosporidium parvum, from wastewaters is becoming of increasing importance in the UK, especially since contamination of raw waters by sewage effluents has been implicated in major waterborne outbreaks of cryptosporidiosis in recent years. Compared to conventional wastewater-treatment processes, constructed wetlands have demonstrated favourable removal rates for Cryptosporidium oocysts. The removal mechanisms, however, remain unknown. Predation by free-living ciliated protozoa, which are commonly found in constructed wetlands, was investigated as a possible mechanism for oocyst removal. In laboratory feeding experiments, ciliates (Euplotes patella, Stylonychia mytilus, Paramecium caudatum and an unidentified wetland ciliate species), were exposed to doses ranging from 10 to 106 oocysts/ml for between 5 and 60 minutes. Ciliate predatory activities were assessed by enumerating fluorescently labelled ingested oocysts using epifluorescence microscopy. Oocysts were found to be ingested by all species investigated. Paramecium demonstrated the highest mean ingestion rates (up to 170 oocysts/hr) followed by Stylonychia (up to 60 oocysts/hour). Euplotes and the wetland ciliate had lower mean grazing rates (4 and 10 oocysts/hr respectively). These results indicate that protozoan predation may be an important factor in the removal of Cryptosporidium oocysts from wastewaters in constructed wetlands.
19
DURÁN-RAMÍREZ, CARLOS ALBERTO, ROBERTO JÚNIO PEDROSO DIAS, and ROSAURA MAYÉN-ESTRADA. "Checklist of ciliates (Alveolata: Ciliophora) that inhabit in bromeliads from the Neotropical Region." Zootaxa 4895, no. 1 (December 14, 2020): 1–36. http://dx.doi.org/10.11646/zootaxa.4895.1.1.
Full textAbstract:
Species from almost all classes of ciliates are prone to be found inhabiting bromeliads in the Neotropics, from Mexico to Brazil, and the Antilles. Studies of ciliates recorded from bromeliads have been carried out from few bromeliad species, mainly in tropical forest. We compiled all available data of free living and sessile ciliates from bromeliads, including their geographic distribution and bromeliad identity. We provide a list of 170 ciliate species that have been recorded in 52 epiphytic and terrestrial bromeliad species, distributed in ten Neotropical countries . Most of the species belong to the Classes Oligohymenophorea, Colpodea and Spirotrichea. The largest number of ciliate species has been recorded in Brazil and Mexico. Bromeliothrix metopoides and Glaucomides bromelicola were the two species with the widest geographical distribution, 19 species have been recorded only in Mexico, 11 in the Antillean islands, and 89 only in Southamerica. Free living species prevailed over sessile species, and both represent 2% of the total ciliate species number. Sixteen ciliate species have been recorded only inhabiting in bromeliads. Although bromeliads show a high endemicity, their specificity is low in relation to ciliates.
20
Kalinowska, Krystyna, and Maciej Karpowicz. "Ice-on and ice-off dynamics of ciliates and metazooplankton in the Łuczański Canal (Poland)." Aquatic Ecology 54, no. 4 (September 1, 2020): 1121–34. http://dx.doi.org/10.1007/s10452-020-09797-3.
Full textAbstract:
Abstract The ciliate–metazooplankton trophic coupling is well documented from both laboratory and field experiments. The knowledge about these relationships during winter ice-covered periods is very scarce. The abundance and composition of planktonic ciliates, rotifers and crustaceans were studied during the ice-covered and ice-free periods in the Łuczański Canal (Masurian Lakeland, Poland). We hypothesised that in winter, rotifers play a major role in the top-down control of ciliates and that ciliate–metazooplankton relationships differ not only between the ice-covered and ice-free periods, but also between ice-covered months. Our study showed that ciliates formed a significant part of zooplankton biomass during the winter ice-covered period when crustaceans occurred in very low abundances. Despite cold water temperature and the presence of ice cover, time was probably a cue that initiates zooplankton development. The ciliate, rotifer and crustacean numbers and biomass, as well as chlorophyll a concentrations, were lower in February than in ice-free periods. In the winter month with ice cover, bottom-up control by resources was more important than top-down control by zooplankton grazing in regulating ciliates. In the spring month with ice cover, crustaceans and rotifers may include ciliates as an important part of their diets. In April, the studied groups of organisms were not related to each other in contrast to the summer, when zooplankton communities were closely related to each other. In autumn, rotifers may play an important role in controlling ciliates. The abundance, composition and ciliate–metazoan relationships can vary considerably not only across seasons, but also across ice-covered months.
21
Matsuda, Atsushi, Annie Wan-Yi Shieh, Douglas L. Chalker, and James D. Forney. "The Conjugation-Specific Die5 Protein Is Required for Development of the Somatic Nucleus in both Paramecium and Tetrahymena." Eukaryotic Cell 9, no. 7 (May 21, 2010): 1087–99. http://dx.doi.org/10.1128/ec.00379-09.
Full textAbstract:
ABSTRACTDevelopment in ciliated protozoa involves extensive genome reorganization within differentiating macronuclei, which shapes the somatic genome of the next vegetative generation. Major events of macronuclear differentiation include excision of internal eliminated sequences (IESs), chromosome fragmentation, and genome amplification. Proteins required for these events include those with homology throughout eukaryotes as well as proteins apparently unique to ciliates. In this study, we identified the ciliate-specificDefective inIESExcision 5 (DIE5) genes ofParamecium tetraurelia(PtDIE5) andTetrahymena thermophila(TtDIE5) as orthologs that encode nuclear proteins expressed exclusively during development. Abrogation of PtDie5 protein (PtDie5p) function by RNA interference (RNAi)-mediated silencing or TtDie5p by gene disruption resulted in the failure of developing macronuclei to differentiate into new somatic nuclei.TetrahymenaΔDIE5cells arrested late in development and failed to complete genome amplification, whereas RNAi-treatedParameciumcells highly amplified new macronuclear DNA before the failure in differentiation, findings that highlight clear differences in the biology of these distantly related species. Nevertheless, IES excision and chromosome fragmentation failed to occur in either ciliate, which strongly supports that Die5p is a critical player in these processes. InTetrahymena, loss of zygotic expression during development was sufficient to block nuclear differentiation. This observation, together with the finding that knockdown of Die5p inParameciumstill allows genome amplification, indicates that this protein acts late in macronuclear development. Even though DNA rearrangements in these two ciliates look to be quite distinct, analysis ofDIE5establishes the action of a conserved mechanism within the genome reorganization pathway.
22
Vlaičević, Barbara, Renata Matoničkin Kepčija, Vesna Gulin, Ivana Turković Čakalić, Mirjana Kepec, and Dubravka Čerba. "Key drivers influencing the colonization of periphytic ciliates and their functional role in hydrologically dynamic floodplain lake ecosystem." Knowledge & Management of Aquatic Ecosystems, no. 422 (2021): 33. http://dx.doi.org/10.1051/kmae/2021032.
Full textAbstract:
We investigated the colonization process and community dynamics of periphytic ciliates in a floodplain lake. To elucidate the functional role of ciliates, we investigated variations in their functional traits during colonization. Our research revealed that ciliate colonization process differs significantly between spring and summer, mainly due to differences in water temperature and hydrological regime. The most pronounced influence of temperature-initiated differences was observed during the initial phase of colonization, during which faster colonization with different pioneer species, and more diverse and abundant ciliate community characterized the summer initial phase. Hydrological changes significantly affected periphytic communities during the intermediate and late phases, resulting in different patterns of the colonization process. Mitigation of suspended food particles during flooding periods led to a decrease in ciliate abundance and the dominance of mobile benthivore ciliates (raptorial and filter feeders), whilst during more stable periods of low water, sessile planktivores (filter feeders) that consume suspended particles, dominated. They are considered to be main representatives of periphytic ciliates in floodplain lakes, playing a significant role in the pelagic-benthic coupling. The results of the present study offer new insights into the ecology and functional role of periphytic ciliates in a floodplain ecosystems of temperate regions.
23
Ulstrup, Karin E., Michael Kühl, and David G. Bourne. "Zooxanthellae Harvested by Ciliates Associated with Brown Band Syndrome of Corals Remain Photosynthetically Competent." Applied and Environmental Microbiology 73, no. 6 (January 26, 2007): 1968–75. http://dx.doi.org/10.1128/aem.02292-06.
Full textAbstract:
ABSTRACT Brown band syndrome is a new coral affliction characterized by a local accumulation of yet-unidentified ciliates migrating as a band along the branches of coral colonies. In the current study, morphologically intact zooxanthellae (= Symbiodinium) were observed in great numbers inside the ciliates (>50 dinoflagellates per ciliate). Microscale oxygen measurements and variable chlorophyll a fluorescence analysis along with microscopic observations demonstrated that zooxanthellae within the ciliates are photosynthetically competent and do not become compromised during the progression of the brown band zone. Zooxanthellae showed similar trends in light acclimation in a comparison of rapid light curve and steady-state light curve measures of variable chlorophyll a fluorescence. Extended light exposure of steady-state light curves resulted in higher quantum yields of photosystem II. The brown band tissue exhibited higher photosynthetically active radiation absorptivity, indicating more efficient light absorption due to a higher density of zooxanthellae in the ciliate-dominated zone. This caused relatively higher gross photosynthesis rates in the zone with zooxanthella-containing ciliates compared to healthy coral tissue. The observation of photosynthetically active intracellular zooxanthellae in the ciliates suggests that the latter can benefit from photosynthates produced by ingested zooxanthellae and from photosynthetic oxygen production that alleviates diffusion limitation of oxic respiration in the densely populated brown band tissue. It remains to be shown whether the zooxanthellae form a stable symbiotic association with the ciliate or are engulfed incidentally during grazing on coral tissue and then maintained as active inside the ciliate for a period before being digested and replaced by new zooxanthellae.
24
Aslan, Erhan, Nurçin Küçükoğlu, and Muhittin Arslanyolu. "A comparative in-silico analysis of autophagy proteins in ciliates." PeerJ 5 (January 17, 2017): e2878. http://dx.doi.org/10.7717/peerj.2878.
Full textAbstract:
Autophagy serves as a turnover mechanism for the recycling of redundant and/or damaged macromolecules present in eukaryotic cells to re-use them under starvation conditions via a double-membrane structure known as autophagosome. A set of eukaryotic genes called autophagy-related genes (ATGs) orchestrate this highly elaborative process. The existence of these genes and the role they play in different eukaryotes are well-characterized. However, little is known of their role in some eukaryotes such as ciliates. Here, we report the computational analyses of ATG genes in five ciliate genomes to understand their diversity. Our results show that Oxytricha trifallax is the sole ciliate which has a conserved Atg12 conjugation system (Atg5-Atg12-Atg16). Interestingly, Oxytricha Atg16 protein includes WD repeats in addition to its N-terminal Atg16 domain as is the case in multicellular organisms. Additionally, phylogenetic analyses revealed that E2-like conjugating protein Atg10 is only present in Tetrahymena thermophila. We fail to find critical autophagy components Atg5, Atg7 and Atg8 in the parasitic ciliate Ichthyophthirius multifiliis. Contrary to previous reports, we also find that ciliate genomes do not encode typical Atg1 since all the candidate sequences lack an Atg1-specific C-terminal domain which is essential for Atg1 complex formation. Consistent with the absence of Atg1, ciliates also lack other members of the Atg1 complex. However, the presence of Atg6 in all ciliates examined here may rise the possibility that autophagosome formation could be operated through Atg6 in ciliates, since Atg6 has been shown as an alternative autophagy inducer. In conclusion, our results highlight that Atg proteins are partially conserved in ciliates. This may provide a better understanding for the autophagic destruction of the parental macronucleus, a developmental process also known as programmed nuclear death in ciliates.
25
DURÁN-RAMÍREZ, CARLOS ALBERTO, and ROSAURA MAYÉN-ESTRADA. "Ciliate species from tank-less bromeliads in a dry tropical forest and their geographical distribution in the Neotropics." Zootaxa 4497, no. 2 (October 8, 2018): 241. http://dx.doi.org/10.11646/zootaxa.4497.2.5.
Full textAbstract:
The study of ciliate diversity in tropical environments remains scarce. In Neotropical forests, bromeliads are a common component of the vascular flora; bromeliads with tank morphology intercept rain water and detritus, resulting in the formation of a phytotelm, where heterotrophic protist communities like ciliates can establish. However, it is not known if ciliates inhabit tank-less bromeliads. For this reason, the goal of the present study was to investigate if ciliates can establish between the leaf axils of five terrestrial and epiphytic tank-less bromeliad species in a dry tropical forest in west Mexico. We collected samples of rain water and detritus from the leaf axils during the humid season of years 2015 and 2016. For ciliate taxonomical identification, we used optical microscopy, in vivo observation, and silver impregnation techniques. To summarize information about geographical distribution of ciliates identified at species level in the Neotropics, we provided their records from previous works, at country level with locality and georeferenciation. We recorded 27 taxa of ciliates, where the class Oligohymenophorea contained the largest richness of taxa. Drepanomonas revoluta, Leptopharynx bromeliophilus, and Tetrahymena sp. were recorded from all the species of bromeliads. Bromelia karatas was the species that hosted the largest number of ciliate taxa (22). Our results indicated that Glaucomides bromelicola, Gonostomum bromelicola, Leptopharynx bromelicola and L. bromeliophilus, species which are considered endemic to tank bromeliads, can also inhabit tank-less bromeliads. We provided previous records of 19 ciliate species from eleven countries within the Neotropical region, and Bromeliothrix metopoides was the species most frequently recorded in Neotropical countries (9). Therefore, tank-less bromeliads can constitute a temporal habitat for ciliates, and function as cysts reservoirs in environments with a pronounced seasonality like dry tropical forests.
26
Li, Jing, Qingyu Liao, Mei Li, Jinhong Zhang, Nora Fungyee Tam, and Runlin Xu. "Community Structure and Biodiversity of Soil Ciliates at Dongzhaigang Mangrove Forest in Hainan Island, China." Applied and Environmental Soil Science 2010 (2010): 1–8. http://dx.doi.org/10.1155/2010/103819.
Full textAbstract:
The distribution of soil ciliates in three different habitats within a typical mangrove forest in Dongzhaigang, Hainan, China was investigated. The abundance, biodiversity, and community similarity of ciliates in fresh and air-dried soil with different, physical/chemical properties were analyzed. Three Classes, 11 Orders, 34 Genera, and 70 species of ciliates were found with the first dominant group being Hypotrichida. Ciliate biodiversities followed Site B < Site A < Site C in both fresh and dried samples. Ciliate abundance was positively correlated with soil moisture, salinity, organic matter (OM), total nitrogen (TN), total phosphorus (TP), and sulfate (SO42−), but negatively with pH and total potassium (TK). Site A and Site B and Site B and Site C showed the highest similarity in fresh and dried samples, respectively. The ubiquitous characteristics of ciliate distribution suggested their important role in food webs and nutrient cycling. The presence of Colpodida was linked with mangrove plants.
27
Grimes, G. W., and R. H. Gavin. "Ciliary protein conservation during development in the ciliated protozoan, Oxytricha." Journal of Cell Biology 105, no. 6 (December 1, 1987): 2855–59. http://dx.doi.org/10.1083/jcb.105.6.2855.
Full textAbstract:
The ciliated protozoan Oxytricha fallax possesses multiple highly localized clusters of basal bodies and cilia, all of which are broken down and rebuilt during prefission morphogenesis-with one major exception. The adoral zone of membranelles (AZM) of the ciliate oral apparatus contains approximately 1,500-2,000 basal bodies and cilia, and it is the only compound ciliary structure that is passed morphologically intact to one daughter cell at each cell division. By labeling all proteins in cells, and then picking the one daughter cell possessing the original labeled AZM, we could then evaluate whether or not the ciliary proteins of the AZM were diluted (i.e., either by degradation to constituent amino acids or by subunit exchange) during cell division. Autoradiographic analysis demonstrated that the label was highly conserved in the AZM (i.e., we saw no evidence of turnover), and electrophoretic data illustrate that at least one of the proteins of the AZM is tubulin. We, therefore, conclude that for at least some of the ciliary and basal body proteins of Oxytricha fallax, AZM morphological conservation is essentially equivalent to molecular conservation.
28
Kittelmann, Sandra, Savannah R. Devente, Michelle R. Kirk, Henning Seedorf, Burk A. Dehority, and Peter H. Janssen. "Phylogeny of Intestinal Ciliates, Including Charonina ventriculi, and Comparison of Microscopy and 18S rRNA Gene Pyrosequencing for Rumen Ciliate Community Structure Analysis." Applied and Environmental Microbiology 81, no. 7 (January 23, 2015): 2433–44. http://dx.doi.org/10.1128/aem.03697-14.
Full textAbstract:
ABSTRACTThe development of high-throughput methods, such as the construction of 18S rRNA gene clone or pyrosequencing libraries, has allowed evaluation of ciliate community composition in hundreds of samples from the rumen and other intestinal habitats. However, several genera of mammalian intestinal ciliates have been described based only on morphological features and, to date, have not been identified using molecular methods. Here, we isolated single cells of one of the smallest but widely distributed intestinal ciliates,Charonina ventriculi, and sequenced its 18S rRNA gene. We verified the sequence in a full-cycle rRNA approach using fluorescencein situhybridization and thereby assigned an 18S rRNA gene sequence to this species previously known only by its morphology. Based on its full-length 18S rRNA gene sequence,Charonina ventriculiwas positioned within the phylogeny of intestinal ciliates in the subclass Trichostomatia. The taxonomic framework derived from this phylogeny was used for taxonomic assignment of trichostome ciliate 18S rRNA gene sequence data stemming from high-throughput amplicon pyrosequencing of rumen-derived DNA samples. The 18S rRNA gene-based ciliate community structure was compared to that obtained from microscopic counts using the same samples. Both methods allowed identification of dominant members of the ciliate communities and classification of the rumen ciliate community into one of the types first described by Eadie in 1962. Notably, each method is associated with advantages and disadvantages. Microscopy is a highly accurate method for evaluation of total numbers or relative abundances of different ciliate genera in a sample, while 18S rRNA gene pyrosequencing represents a valuable alternative for comparison of ciliate community structure in a large number of samples from different animals or treatment groups.
29
Dopheide, Andrew, Gavin Lear, Rebecca Stott, and Gillian Lewis. "Relative Diversity and Community Structure of Ciliates in Stream Biofilms According to Molecular and Microscopy Methods." Applied and Environmental Microbiology 75, no. 16 (June 26, 2009): 5261–72. http://dx.doi.org/10.1128/aem.00412-09.
Full textAbstract:
ABSTRACT Ciliates are an important component of aquatic ecosystems, acting as predators of bacteria and protozoa and providing nutrition for organisms at higher trophic levels. Understanding of the diversity and ecological role of ciliates in stream biofilms is limited, however. Ciliate diversity in biofilm samples from four streams subject to different impacts by human activity was assessed using microscopy and terminal restriction fragment length polymorphism (T-RFLP) analysis of 18S rRNA sequences. Analysis of 3′ and 5′ terminal fragments yielded very similar estimates of ciliate diversity. The diversity detected using microscopy was consistently lower than that suggested by T-RFLP analysis, indicating the existence of genetic diversity not apparent by morphological examination. Microscopy and T-RFLP analyses revealed similar relative trends in diversity between different streams, with the lowest level of biofilm-associated ciliate diversity found in samples from the least-impacted stream and the highest diversity in samples from moderately to highly impacted streams. Multivariate analysis provided evidence of significantly different ciliate communities in biofilm samples from different streams and seasons, particularly between a highly degraded urban stream and less impacted streams. Microscopy and T-RFLP data both suggested the existence of widely distributed, resilient biofilm-associated ciliates as well as ciliate taxa restricted to sites with particular environmental conditions, with cosmopolitan taxa being more abundant than those with restricted distributions. Differences between ciliate assemblages were associated with water quality characteristics typical of urban stream degradation and may be related to factors such as nutrient availability and macroinvertebrate communities. Microscopic and molecular techniques were considered to be useful complementary approaches for investigation of biofilm ciliate communities.
30
Qiu, Dajun, Liangmin Huang, Hui Huang, Jianhui Yang, and Senjie Lin. "Two Functionally Distinct Ciliates Dwelling in Acropora Corals in the South China Sea near Sanya, Hainan Province, China." Applied and Environmental Microbiology 76, no. 16 (June 25, 2010): 5639–43. http://dx.doi.org/10.1128/aem.03009-09.
Full textAbstract:
ABSTRACT We detected and characterized two distinct scuticociliate ciliates inside Acropora corals in the South China Sea. One, voraciously foraging on Symbiodinium, resembled the brown band disease of ciliates. The other, which is closely related to Paranophrys magna, grazed on detritus instead of Symbiodinium. These two ciliates may serve contrasting functions (competitor versus “cleaner”) in the coral-ciliate-Symbiodinium triangular relationship.
31
Weber, S. D., W. Ludwig, K. H. Schleifer, and J. Fried. "Microbial Composition and Structure of Aerobic Granular Sewage Biofilms." Applied and Environmental Microbiology 73, no. 19 (August 17, 2007): 6233–40. http://dx.doi.org/10.1128/aem.01002-07.
Full textAbstract:
ABSTRACT Aerobic activated sludge granules are dense, spherical biofilms which can strongly improve purification efficiency and sludge settling in wastewater treatment processes. In this study, the structure and development of different granule types were analyzed. Biofilm samples originated from lab-scale sequencing batch reactors which were operated with malthouse, brewery, and artificial wastewater. Scanning electron microscopy, light microscopy, and confocal laser scanning microscopy together with fluorescence in situ hybridization (FISH) allowed insights into the structure of these biofilms. Microscopic observation revealed that granules consist of bacteria, extracellular polymeric substances (EPS), protozoa and, in some cases, fungi. The biofilm development, starting from an activated sludge floc up to a mature granule, follows three phases. During phase 1, stalked ciliated protozoa of the subclass Peritrichia, e.g., Epistylis spp., settle on activated sludge flocs and build tree-like colonies. The stalks are subsequently colonized by bacteria. During phase 2, the ciliates become completely overgrown by bacteria and die. Thereby, the cellular remnants of ciliates act like a backbone for granule formation. During phase 3, smooth, compact granules are formed which serve as a new substratum for unstalked ciliate swarmers settling on granule surfaces. These mature granules comprise a dense core zone containing bacterial cells and EPS and a loosely structured fringe zone consisting of either ciliates and bacteria or fungi and bacteria. Since granules can grow to a size of up to several millimeters in diameter, we developed and applied a modified FISH protocol for the study of cryosectioned biofilms. This protocol allows the simultaneous detection of bacteria, ciliates, and fungi in and on granules.
32
Rychert, Krzysztof, Magdalena Wielgat-Rychert, and Łukasz Lemańczyk. "Impact of the Słupia River waters on microbial communities in the port of Ustka and adjacent Baltic Sea waters." Oceanological and Hydrobiological Studies 47, no. 4 (December 19, 2018): 429–38. http://dx.doi.org/10.1515/ohs-2018-0040.
Full textAbstract:
Abstract The distribution of bacterial and ciliate abundance, ciliate community composition and other parameters were studied during summer along a transect from the mouth of the Słupia River to offshore waters (southern Baltic Sea). Bacteria were examined under an epifluorescence microscope and ciliates were observed under an inverted microscope. Two water masses were identified along the transect. Less saline waters in the river mouth and in the surface layer in the port of Ustka were characterized by high bacterial abundance (5.51–6.16 × 106 ml−1) and low ciliate abundance (0.34–0.90 cells ml−1). More saline waters in the near-bottom zone in the port of Ustka and in the surface layer outside the port contained smaller numbers of bacteria (0.99–2.14 × 106 ml−1) and larger numbers of ciliates (2.65–5.40 cells ml−1). The differences were statistically significant. The separation of the two water masses indicated that the Słupia River exerted a minor impact on the marine waters. The ciliate community composition changed along the transect studied. The main statistically significant difference observed was the low contribution of oligotrichs and choreotrichs to ciliate biomass (3–4%) in less saline waters and their dominance (45–80% of ciliate biomass) in more saline waters.
33
Pinheiro, Marcel D. O., Mary E. Power, Barbara J. Butler, Vivian R. Dayeh, Robin Slawson, Lucy E. J. Lee, Denis H. Lynn, and Niels C. Bols. "Use of Tetrahymena thermophila To Study the Role of Protozoa in Inactivation of Viruses in Water." Applied and Environmental Microbiology 73, no. 2 (November 17, 2006): 643–49. http://dx.doi.org/10.1128/aem.02363-06.
Full textAbstract:
ABSTRACT The ability of a ciliate to inactivate bacteriophage was studied because these viruses are known to influence the size and diversity of bacterial populations, which affect nutrient cycling in natural waters and effluent quality in sewage treatment, and because ciliates are ubiquitous in aquatic environments, including sewage treatment plants. Tetrahymena thermophila was used as a representative ciliate; T4 was used as a model bacteriophage. The T4 titer was monitored on Escherichia coli B in a double-agar overlay assay. T4 and the ciliate were incubated together under different conditions and for various times, after which the mixture was centrifuged through a step gradient, producing a top layer free of ciliates. The T4 titer in this layer decreased as coincubation time increased, but no decrease was seen if phage were incubated with formalin-fixed Tetrahymena. The T4 titer associated with the pellet of living ciliates was very low, suggesting that removal of the phage by Tetrahymena inactivated T4. When Tetrahymena cells were incubated with SYBR gold-labeled phage, fluorescence was localized in structures that had the shape and position of food vacuoles. Incubation of the phage and ciliate with cytochalasin B or at 4°C impaired T4 inactivation. These results suggest the active removal of T4 bacteriophage from fluid by macropinocytosis, followed by digestion in food vacuoles. Such ciliate virophagy may be a mechanism occurring in natural waters and sewage treatment, and the methods described here could be used to study the factors influencing inactivation and possibly water quality.
34
Pauleto, GM, LFM Velho, PRB Buosi, AFS Brão, FA Lansac-Tôha, and CC Bonecker. "Spatial and temporal patterns of ciliate species composition (Protozoa: Ciliophora) in the plankton of the Upper Paraná River floodplain." Brazilian Journal of Biology 69, no. 2 suppl (June 2009): 517–27. http://dx.doi.org/10.1590/s1519-69842009000300007.
Full textAbstract:
Spatial and temporal patterns of plankton ciliates species composition in the Paraná River floodplain were investigated. Samplings were carried out in twelve environments in two distinct hydrological periods (limnophase and potamophase). A total of 61 species of ciliates were recorded, and among them 21 are classified as pelagic while 40 are considered preferentially as littoral species. The registered species belong to eleven orders, and among them, Prostomatida was the most specious followed by Hymenostomatida and Peritrichida. The ciliate species composition was significantly distinct between periods, but not among environments. In this way, typically pelagic species characterized the ciliate community during the limnophase period, while the littoral species were predominant during the potamophase period. Our results strongly support the idea of the flood pulse as the main factor driving the composition pattern of the planktonic ciliates community in the Paraná River floodplain.
35
Dias, Roberto Júnio Pedroso, Sthefane D'Ávila, and Marta D'Agosto. "First record of epibionts peritrichids and suctorians (Protozoa, Ciliophora) on Pomacea lineata (Spix, 1827)." Brazilian Archives of Biology and Technology 49, no. 5 (September 2006): 807–12. http://dx.doi.org/10.1590/s1516-89132006000600015.
Full textAbstract:
This study made a survey on the ciliate protozoans from Peritrichid and Suctorian taxa, epibionts of Pomacea lineata (Spix, 1827) (Ampullariidae). Fifty mollusks were collected in places of irrigation ditches and shell was scraped with a scalpel and the extracted material was analyzed in vivo by light microscopy. All examined mollusks presented epibiont ciliates on their shells. For the first time epibiont ciliates in P. lineata was record. Seven genera of ciliates: five peritrichids and two suctorians, were identified and classified within the subclass Peritrichia: Carchesium Ehrenberg, 1838 (Vorticellidae), Epistylis Ehrenberg, 1830 (Epistylidae), Opercularia Stein, 1854 (Operculariidae), Vaginicola Lamarck, 1816 (Vaginicolidae) and Vorticella Linnaeus, 1767 (Vorticellidae); and Suctoria: Acineta Ehrenberg,1834 (Acinetidae) and Tokophrya Bütschli,1889 (Tokophrydae). The results showed that P. lineata constitute the microenvironment of a ciliate protozoan community that presents complex trophic interactions.
36
Fonty, Gérard, Jean Senaud, Jean-Pierre Jouany, and Philippe Gouet. "Establishment of ciliate protozoa in the rumen of conventional and conventionalized lambs: influence of diet and management conditions." Canadian Journal of Microbiology 34, no. 3 (March 1, 1988): 235–41. http://dx.doi.org/10.1139/m88-044.
Full textAbstract:
The establishment of ciliate protozoa in the rumen was studied in conventional lambs reared under different conditions of management. The role of the microflora in the kinetics of this establishment was also investigated in conventionalized lambs. In lambs reared under farm conditions ciliate protozoa appeared in the following order: Entodinium (15-20 days), Polyplastron, Eudiplodinium, and Epidinium (20–25 days), and Isotricha (50 days). Entodinium was the most abundant (105–106 ciliates mL−1). During the 3rd month, ciliates disappeared spontaneously in about 60% of the lambs during a period that varied from 1 to 4 weeks. In lambs fed only cow's milk Entodinium spp. and Polyplastron multivesiculatum became established at low levels. The results obtained with the conventionalized lambs demonstrate that the establishment of the ciliates in the rumen requires that the bacterial flora be well established beforehand.
37
CHATTERJEE, TAPAS, IGOR DOVGAL, VLADIMIR PEŠIĆ, and ANDRZEJ ZAWAL. "A checklist of epibiont suctorian and peritrich ciliates (Ciliophora) on halacarid and hydrachnid mites (Acari: Halacaridae & Hydrachnidia)." Zootaxa 4457, no. 3 (August 9, 2018): 415. http://dx.doi.org/10.11646/zootaxa.4457.3.4.
Full textAbstract:
Based on published records and original data, a list of the epibiont suctorian and peritrich ciliates (Ciliophora) on halacarid and hydrachnid mites is presented. Altogether 13 suctorian and 10 peritrich species from hydrachnid and halacarid mites were listed. From this list, six suctorian and one peritrich species have been reported from halacarid mites, while four suctorian and four peritrich species were found on hydrachnid mites determined up to species level. The remaining specimens were determined upto the generic level. The halacarid and hydrachnid species do not share any suctorian and peritrich species and some of the ciliate species are specific to certain taxonomic groups of the hosts.The host specificity of both suctorian and peritrich ciliates, localization on the host body and environment are discussed. Some ciliate species specific to hydrachnid mites prefer lotic or lentic habitats. In most cases, both suctorian and peritrich ciliates prefer only marine or only fresh water bodies. It was also mentioned that both suctorian and peritrich ciliates have not distinct preferences in localization on their host body.
38
Schilde, Christina, Barbara Schönemann, Ivonne M. Sehring, and Helmut Plattner. "Distinct Subcellular Localization of a Group of Synaptobrevin-Like SNAREs in Paramecium tetraurelia and Effects of Silencing SNARE-Specific Chaperone NSF." Eukaryotic Cell 9, no. 2 (December 18, 2009): 288–305. http://dx.doi.org/10.1128/ec.00220-09.
Full textAbstract:
ABSTRACT We have identified new synaptobrevin-like SNAREs and localized the corresponding gene products with green fluorescent protein (GFP)-fusion constructs and specific antibodies at the light and electron microscope (EM) levels. These SNAREs, named Paramecium tetraurelia synaptobrevins 8 to 12 (PtSyb8 to PtSyb12), showed mostly very restricted, specific localization, as they were found predominantly on structures involved in endo- or phagocytosis. In summary, we found PtSyb8 and PtSyb9 associated with the nascent food vacuole, PtSyb10 near the cell surface, at the cytostome, and in close association with ciliary basal bodies, and PtSyb11 on early endosomes and on one side of the cytostome, while PtSyb12 was found in the cytosol. PtSyb4 and PtSyb5 (identified previously) were localized on small vesicles, PtSyb5 probably being engaged in trichocyst (dense core secretory vesicle) processing. PtSyb4 and PtSyb5 are related to each other and are the furthest deviating of all SNAREs identified so far. Because they show no similarity with any other R-SNAREs outside ciliates, they may represent a ciliate-specific adaptation. PtSyb10 forms small domains near ciliary bases, and silencing slows down cell rotation during depolarization-induced ciliary reversal. NSF silencing supports a function of cell surface SNAREs by revealing vesicles along the cell membrane at sites normally devoid of vesicles. The distinct distributions of these SNAREs emphasize the considerable differentiation of membrane trafficking, particularly along the endo-/phagocytic pathway, in this protozoan.
39
Ratsak, C. H., B. W. Kooi, and H. W. van Verseveld. "Biomass Reduction and Mineralization Increase Due to the Ciliate Tetrahymena pyriformis Grazing on the Bacterium Pseudomonas fluorescens." Water Science and Technology 29, no. 7 (April 1, 1994): 119–28. http://dx.doi.org/10.2166/wst.1994.0322.
Full textAbstract:
The currently high sludge production and increasing processing costs call for waste-water treatment plants with high purification efficiency and low biomass production. We studied the latter issue through two-stage chemostat cascades to assess the overall biomass reduction due to ciliate grazing. The bacteria were cultured in the first chemostat whereas the ciliates, grazing on the bacteria from the first chemostat, were cultured in the second chemostat. Mathematical modelling was used to describe the bacteria/ciliate dynamics and some of the growth parameters were fitted. In the second chemostat 22-44% of the carbon originating from the first chemostat was mineralized to CO2. An extra biomass reduction of 12-43% was possible due to grazing by the ciliates. At lower growth rates of the ciliates the extra biomass reduction was higher than at high growth rates. This finding is auspicious, suggesting that predator organisms indeed can reduce sludge production.
40
Taylor, William D., and Miriam L. Heynen. "Seasonal and Vertical Distribution of Ciliophora in Lake Ontario." Canadian Journal of Fisheries and Aquatic Sciences 44, no. 12 (December 1, 1987): 2185–91. http://dx.doi.org/10.1139/f87-268.
Full textAbstract:
Ciliated protozoa were sampled at discrete depths from April through October 1982 at a nearshore (38 m depth) and an offshore (178 m depth) station in Lake Ontario. Nearshore, ciliates increased from less than 1 g∙m−2 in early spring to a maximum of about 5 g∙m−2 (wet weight) inside the thermal bar in late May and early June. Summer values varied around 2 g∙m−2 and declined even further in October. Offshore ciliate biomass was relatively constant; the observed range was only 2.8–6.5 g∙m−2. Early spring biomass was much higher than nearshore, suggesting that a significant population persists through the winter, but the spring biomass increase was later. Although biomass concentration was greater in the epilimnion, on an areal basis most of the population resided in the hypolimnion. The hypolimnetic population declined during the summer period of thermal stratification. The observed number of taxa ranged from 15 to 30 per sample. Most had distinct seasonal and vertical distributions. The majority appear to be algivores, but the role of ciliates in the food web of Lake Ontario remains largely unknown. Their biomass is comparable with that of metazoan zooplankton, and with their higher metabolic rates, they probably perform much more of the total grazing.
41
Pettigrosso, Rosa E., and Cecilia A. Popovich. "Phytoplankton-aloricate ciliate community in the Bahía Blanca Estuary (Argentina): seasonal patterns and trophic groups." Brazilian Journal of Oceanography 57, no. 3 (September 2009): 215–27. http://dx.doi.org/10.1590/s1679-87592009000300005.
Full textAbstract:
The seasonal pattern of the phytoplankton-aloricate ciliate community is an adequate indicator of trophic coupling and nutrient cycling in coastal environments. The size-fractionated, abundance, biomass and composition of a phytoplankton-aloricate ciliate community were ascertained in the Bahía Blanca Estuary from February 1994 to February 1995. In addition, ciliate production and excretion rates by size class were estimated. A winter-early spring diatom bloom was the most important event in the annual cycle. To evaluate the significance of phytoplankton size in the food web, <25 µm and > 25 µm fractions of chlorophyll a were determined; the < 25 µm fraction was dominant. To classify the ciliate community in trophic groups, it was divided into volume-size classes, from <10³ µm³to > 10(5) µm³; this wide range of size indicated the potential prey. The smaller ciliates dominated abundance but the larger ones dominated biomass. Values of total ciliates, ranging from 0.2 to 5.2 x 10³ cells L-1 and 0.55 to 83.9 µg C L-1, and levels of total chlorophyll a reached 40.4 µg L-1 and were higher than those recorded for other temperate estuarine systems. The smaller ciliates were potentially important as nitrogen regenerators in summer and spring, when their estimated production was highest. The annual potential production of 3 mg C L-1 represents a reference parameter from which possible changes in the trophic status of this environment could be predicted.
42
Sua, Luz Fernanda. "Estudio de cilias respiratorias y requerimientos básicos de la muestra para microscopía electrónica de transmisión." Revista Colombiana de Neumología 29, no. 2 (May 10, 2018): 86. http://dx.doi.org/10.30789/rcneumologia.v29.n2.2017.272.
Full textAbstract:
La discinesia ciliar primaria (DCP) es una enfermedad hereditaria, principalmente autosómica recesiva, caracterizada por disfunción de las células ciliadas presentes en los tejidos respiratorio y gonadal, entre otros. La prevalencia aproximada de síndrome de Kartagener, que basa el diagnóstico en el estudio ultraestructural ciliar, es de 1/10 000 nacidos vivos (1, 2). La DCP incluye un grupo de enfermedades en la que las cilias respiratorias son inmóviles (síndrome de inmovilidad ciliar), el movimiento ciliar es discinético e ineficaz (DCP) o no hay cilias (aplasia ciliar), este último es extremadamente infrecuente (1, 3, 4). En 1976, Afzelius describió como origen del trastorno, la ausencia de brazos de dineína en los microtúbulos de las cilias bronquiales y de los flagelos de los espermatozoides (5). La célula ciliada normal se compone por unas 250 proteínas organizadas en torno a un axonema o conjunto de microtúbulos, que se extiende desde el citoplasma hasta el extremo final de la cilia. La cilia normal consiste en un par central de microtúbulos rodeados por una vaina y otros 9 dobletes externos, formando la organización característica «9+2». Los complejos de dineína se asocian con los dobletes periféricos; los puentes de nexina sostienen los dobletes periféricos entre sí; y los rayos radiales (radial spoke) unen el par central con los periféricos.
43
Purschke, Günter. "Comparative electron microscopic investigation of the nuchal organs in Protodriloides, Protodrilus, and Saccocirrus (Annelida, Polychaeta)." Canadian Journal of Zoology 68, no. 2 (February 1, 1990): 325–38. http://dx.doi.org/10.1139/z90-048.
Full textAbstract:
The nuchal organs of the interstitial polychaetes Protodriloides chaetifer, Protodriloides symbioticus, Protodrilus ciliatus, Protodrilus adhaerens, Saccocirrus krusadensis, and Saccocirrus papillocercus were investigated by scanning and transmission electron microscopy. These organs vary from spherical to elongated ciliary brushes and usually lie in shallow pits. In P. symbioticus only a reduced nuchal organ exists, whereas the other species all have well-developed nuchal organs of similar structure consisting of ciliated supportive cells and bipolar primary sensory cells. The perikarya of the sensory cells form the nuchal ganglia, which lie behind the brain. Different retractor muscle cells are attached to the ciliated cells. The number of sensory cells varies from 4 to about 90 according to the size of the nuchal organs. Each sensory cell gives rise to a distal process (dendrite), and 4–25 processes at a time unite to form bundles that penetrate between the ciliated cells. Apically the dendrites terminate in small sensory bulbs, each bearing several microvilli and a modified cilium. The sensory cilia usually branch, lose their axonemes, and extend as microvillus-like structures into the olfactory chamber representing an extracellular space below the reduced cuticle. Specific microvillar processes of the ciliated cells form a dense cover above the cuticle which is only penetrated by the motile cilia of these cells. The ciliated cells are highly pinocytic. The nuchal organs of the species investigated show striking similarities to those of spionids.
44
Coppellotti, Olimpia, and Paola Matarazzo. "Ciliate colonization of artificial substrates in the Lagoon of Venice." Journal of the Marine Biological Association of the United Kingdom 80, no. 3 (June 2000): 419–27. http://dx.doi.org/10.1017/s0025315400002113.
Full textAbstract:
In work performed during the period February–October 1996, about 47 species of ciliates were detected in the communities of Aufwuchs, or periphyton, colonizing glass substrates submerged in three sites in the Lagoon of Venice, two in the urban area of Chioggia and one at a mussel-farming site. The ciliate communities were composed of sessile forms of Peritrichia and Suctoria and of motile ciliates, belonging especially to Hypotrichia and Karyorelictea. Four species of the peritrich Zoothamnium and the suctorians Acineta tuberosa and Ephelota gemmipara are reported here for the first time in the Lagoon of Venice. The richest ciliate communities were recovered at 60 cm from the bottom. Processed by multivariate analysis, data of samplings performed up to day ten from the positioning of glass slides indicated significant differences in biotic and physico-chemical parameters, according to season. The first data did not give definite indications on the possibility of using ciliates colonizing solid surfaces to assess the quality of this peculiar environment.
45
Proshkin, Boris V., and Andrey V. Klimov. "Systematic position of Populus ciliata Wall. ex Royle on the study of shoot morphology and petiolar anatomy." SOCIALNO-ECOLOGICHESKIE TECHNOLOGII 10, no. 1 (2020): 9–23. http://dx.doi.org/10.31862/2500-2961-2020-10-1-9-23.
Full textAbstract:
Populus ciliate – ciliated poplar is distributed in the Himalayas at altitudes from 1300 to 3400 m above sea level, along river banks and wet slopes. The systematic position of the taxon remains unclear, although in most modern works it is attributed to the Tacamahaca section. The purpose of this study is to study the morphological features of crown shoots and the anatomical structure of petioles of Populus ciliata leaves to clarify its systematic position. Studies of the morphology of P. ciliata showed that it did not have specialized shortened shoots marking a section of balsamic poplars – diskoblasts. The most important signs of petiolar anatomy allowing the identification of poplar taxa at the section level are: the shape of the petiole cross section, the contours of its adaxial and abaxial sides, the shape of the rings of closed collateral bundles, the shape of the vascular system. A comparison of the obtained sections of P. ciliata with representatives of the Tacamahaca section indicates that the plants studied do not belong to balsamic poplars, since they differ in the absence of a groove pronounced on the adaxial side. The latter in the form of a small recess in the slice is fixed only at the place of its transition into the leaf blade. The contours of the abaxial and adaxial sides are round, the shape of the vascular system of the petiole is not highly arched like that of balsamic poplars, but linear, formed by elliptical rings of closed collateral bundles.
46
Ivanova, Еkaterina, Igor Dovgal, and Alice Newton. "FIRST RECORDS OF EPIBIONT CILIATES (CILIOPHORA) IN METHANE ENRICHED SEDIMENTS WITH SPECIES REDESCRIPTIONS." Ecologica Montenegrina 10 (April 7, 2017): 51–57. http://dx.doi.org/10.37828/em.2017.10.8.
Full textAbstract:
The article is dedicated to re-discovery of ciliates Loricophrya bosporica (Suctorea) and Cothurnia sp. (Peritrichia) found at nematodes from methane seep of the Ria Formosa lagoon (Southern Portugal). Based on authors’ data the lagoon sediments might be attributing to the hypoxic (periodically anoxic) methane seepage environment. The morphological characterizations of found ciliates with emphasis on poorly studied stylotheca structure in suctorian ciliate and macronucleus morphology in peritrich are presented.
47
Dias, Roberto Júnio P., and Marta D'Agosto. "Feeding behavior of Frontonia leucas (Ehrenberg) (Protozoa, Ciliophora, Hymenostomatida) under different environmental conditions in a lotic system." Revista Brasileira de Zoologia 23, no. 3 (September 2006): 758–63. http://dx.doi.org/10.1590/s0101-81752006000300021.
Full textAbstract:
The objective of this study was to record and describe the morphological changes and the ingestion mechanisms of Frontonia leucas (Ehrenberg, 1833) according to the food type and to relate the food ingested with the different environmental conditions in a lotic system, namely São Pedro stream, located in the municipality of Juiz de Fora, Minas Gerais, Brazil. We sampled three points on a monthly basis from August 2002 to June 2003, each of which receiving different levels of untreated sewage. We prepared culture media for the ciliate specimens containing filtered water from each point and the types of food observed inside F. leucas (cyanobacteria, diatoms, desmids and testate amoebas). We observed the ingestion mechanisms of F. leucas in vivo, under a phase contrast optical microscope, using instantaneous sampling and sequence sampling as behavior observation methods, noting the following parameters: dissolved oxygen concentration, pH, conductivity and water temperature. We noted the F. leucas ciliates ingesting diatoms and desmids at collection point 1 and filamentous cyanobacteria, testate amoebas (Arcella and Centropyxis) and rotifers at points 2 and 3. The present work records for the first time the ingestion of testate amoebas of the genus Centropyxis by F. leucas. We noted five ingestion mechanisms by F. leucas while feeding on cyanobacteria and testate amoebas of the genus Centropyxis, three of these related to the ciliary action and two involving physical changes in the cytoplasm. For ingestion of diatoms, desmid (Closterium) and Arcella, the mechanisms involving ciliary action alone were sufficient for ingestion, since these preys are smaller than the ciliate under study. The autecological data registered for F. leucas were 1.98-8.01 mg l-1 O2, pH 6.9-8.73, 58-390 µS/cm and 19.5-26.2ºC, confirming its ample ecological valence.
48
Babko, R., J. Fyda, T. Kuzmina, and A. Hutorowicz. "Ciliates on the Macrophytes in Industrially Heated Lakes (Kujawy Lakeland, Poland)." Vestnik Zoologii 44, no. 6 (January 1, 2010): e-1-e-11. http://dx.doi.org/10.2478/v10058-010-0032-8.
Full textAbstract:
Ciliates on the Macrophytes in Industrially Heated Lakes (Kujawy Lakeland, Poland)The ciliate assemblage on the macrophytes was examined in 2005 during the vegetation period in the Konińskie Lakes which are heating by post-cooling waters from thermal electric plants. As a result of changed temperature regimen the alien thermophilic macrophyteVallisneria spiralisis becoming increasingly common in the littoral zone. A total of 150 ciliate taxa belonging to 27 orders were found. Greater ciliate species diversity was found on architecturally complex, submerged forms such asCeratophyllum demersumandMyriophyllum spicatum. By contrast the ciliate compositions on emergent macrophytes with simple architecture in their submerged parts, such asTypha, Sparganium, orAcorus, were less species rich. Despite the simple architecture ofVallisnerialeaves, the ciliate diversity on them was high. The results show that replacement of native macrophytes by the alien formV. spiralisin heated lakes did not impoverish the ciliate diversity.
49
Omori, Toshihiro, Hiroaki Ito, and Takuji Ishikawa. "Swimming microorganisms acquire optimal efficiency with multiple cilia." Proceedings of the National Academy of Sciences 117, no. 48 (November 16, 2020): 30201–7. http://dx.doi.org/10.1073/pnas.2011146117.
Full textAbstract:
Planktonic microorganisms are ubiquitous in water, and their population dynamics are essential for forecasting the behavior of global aquatic ecosystems. Their population dynamics are strongly affected by these organisms’ motility, which is generated by their hair-like organelles, called cilia or flagella. However, because of the complexity of ciliary dynamics, the precise role of ciliary flow in microbial life remains unclear. Here, we have used ciliary hydrodynamics to show that ciliates acquire the optimal propulsion efficiency. We found that ciliary flow highly resists an organism’s propulsion and that the swimming velocity rapidly decreases with body size, proportional to the power of minus two. Accordingly, the propulsion efficiency decreases as the cube of body length. By increasing the number of cilia, however, efficiency can be significantly improved, up to 100-fold. We found that there exists an optimal number density of cilia, which provides the maximum propulsion efficiency for all ciliates. The propulsion efficiency in this case decreases inversely proportionally to body length. Our estimated optimal density of cilia corresponds to those of actual microorganisms, including species of ciliates and microalgae, which suggests that now-existing motile ciliates and microalgae have survived by acquiring the optimal propulsion efficiency. These conclusions are helpful for better understanding the ecology of microorganisms, such as the energetic costs and benefits of multicellularity in Volvocaceae, as well as for the optimal design of artificial microswimmers.
50
Ekelund, Flemming, Helle B. Frederiksen, and Regin Rønn. "Population Dynamics of Active and Total Ciliate Populations in Arable Soil Amended with Wheat." Applied and Environmental Microbiology 68, no. 3 (March 2002): 1096–101. http://dx.doi.org/10.1128/aem.68.3.1096-1101.2002.
Full textAbstract:
ABSTRACT Soil protozoa are characterized by their ability to produce cysts, which allows them to survive unfavorable conditions (e.g., desiccation) for extended periods. Under favorable conditions, they may rapidly excyst and begin feeding, but even under optimal conditions, a large proportion of the population may be encysted. The factors governing the dynamics of active and encysted cells in the soil are not well understood. Our objective was to determine the dynamics of active and encysted populations of ciliates during the decomposition of freshly added organic material. We monitored, in soil microcosms, the active and total populations of ciliates, their potential prey (bacteria and small protozoa), their potential competitors (amoebae, flagellates, and nematodes), and their potential predators (nematodes). We sampled with short time intervals (2 to 6 days) and generated a data set, suitable for mathematical modeling. Following the addition of fresh organic material, bacterial numbers increased more than 1,400-fold. There was a temporary increase in the number of active ciliates, followed by a rapid decline, although the size of the bacterial prey populations remained high. During this initial burst of ciliate growth, the population of cystic ciliates increased 100-fold. We suggest that internal population regulation is the major factor governing ciliate encystment and that the rate of encystment depends on ciliate density. This model provides a quantitative explanation of ciliatostasis and can explain why protozoan growth in soil is less than that in aquatic systems. Internally governed encystment may be an essential adaptation to an unpredictable environment in which individual protozoa cannot predict when the soil will dry out and will survive desiccation only if they have encysted in time.