DOCSLIB.ORG

Protistology Epigenetic Factors in Vital Functions of the Ciliate Dileptus Anser

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Protistology Epigenetic Factors in Vital Functions of the Ciliate Dileptus Anser Protistology 12 (2), 61–72 (2018) Protistology Epigenetic factors in vital functions of the ciliate Dileptus anser Zoya I. Uspenskaya Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia | Submitted April 17, 2018 | Accepted June 8, 2018 | Summary The article reviews data on serotypes of various clones of the ciliate Dileptus anser and results of hybridologic analysis of the mating types features obtained during the long-term studies. The current knowledge on Dileptus in terms of epigenetic variation and inheritance is summarized and discussed. Key words: ciliates, Dileptus anser, serotypes, mating types, genetics, non-Mendelian inheritance, epigenetics Introduction object not only for protistological but also for the basic biological research. Genetic studies The genetic features of ciliates define their of this ciliate have never been performed until role as useful model organisms for discovering and mid-XXth century, which undoubtedly hinders its understanding the mechanisms of heredity. Early further use as a laboratory model. In the 1970s, genetic analysis carried out by Sonneborn (1937) such studies began in the Laboratory of Cytology showed that the transmission of many heritable of Unicellular Organisms, Institute of Cytology sings cannot be fully explained by the Mendel laws. RAS, St. Petersburg, Russia. The clones of dilepti Today nobody doubts that a substantial role in the were obtained from the individuals isolated at processes of vital functions of a cell belongs to the different times from natural reservoirs in the epigenetic factors. Epigenetics develops rapidly, and Leningrad District. Dilepti were cultivated at 25° the data on epigenetic variability are continuously C in Prescott’s inorganic medium and fed with the supplemented with new important scientific infor- ciliate Tetrahymena pyriformis (Nikolaeva, 1968). mation. Modern views on epigenetic variability This species was a new one for research on genetics are largely influenced by research carried out on and epigenetics of ciliates and highly promising in ciliates. The study of ciliates allowed, thanks to their terms of comparative genetics of these protozoa. For unique biology, to discover some new examples those studies, the characters were selected which of epigenetic heredity. Epigenetics included all were typical for classical genetics of ciliates, namely, inherited changes not related to differences in DNA serotypes and mating types. base sequences (Preer, 1993; Russo et al.,1996). For ciliates, epigenesis can be determined in the Serotypes in Dileptus anser observed cases of non-Mendelian heredity. The ciliate Dileptus anser (Rhynchostomatia, Serotype of ciliates is determined by immunolo- Litostomatea) (see: Adl et al., 2012) is a common gical methods and results from the presence of a doi:10.21685/1680-0826-2018-12-2-1 © 2018 The Author(s) Protistology © 2018 Protozoological Society Affiliated with RAS 62 · Zoya I. Uspenskaya certain class of proteins distributed on the surface of (Uspenskaya, 1988). In 33 combinations, there the cilia and the outer membrane of the cell (Beale was no reaction with heterologous ISs, and it was and Mott, 1962; Doerder, 1981). These proteins are clear evidence that they had some other serotypes called immobilization antigens (i-antigens) because determined by other surface antigens. However, when ciliates are treated with homologous immune in 4 heterologous combinations with one of the serum (IS) in a certain concentration, the cells ISs and in 1 combination with the other one, weak become immobilized. The function of these surface immobilization reaction was registered, indicating proteins is still unknown. The essential features of some similarity of the serotype in reacting to the antigenic structure of ciliates are its diversity and heterologous and homologous clones. Subsequently, variability detected as early as in the 40s of the last some other clones were investigated, and cross- century (see one of the first reviews: Beale, 1954). reactions between the ISs and ciliates cultured at Under different conditions, ciliates of the same clone different temperatures were also observed. These may express different i-antigens. This genic system observations were made for clones #28 and #29, operates on the principle of mutual exclusion of the subclones of each of them being cultured at 25 and genes, i.e. only one i-antigen can be revealed on 17° C. Two ISs were prepared against two cultures the surface of cells at any given moment (Nanney, of #5D clone which were cultured at the same 1980). In some cases, this rule concerns not only temperatures (IS-5D-25 and IS-5D-17). Each IS different genes but also different alleles of the gene. immobilized only homologous (“warm” or “cold”) Exclusions are extremely rare. When changing the #5D cells. Nevertheless, at both temperatures #29 cultivation conditions or under some treatment, the subclones reacted with both of these heterologous replacement of one surface protein with another ISs obtained against 5D cells. Similarly, both IS- one and the cell serotype transformation occurs. 5D-25 and IS-5D-17 immobilized cells of the #28 Of greatest interest in the serotype system in ciliates clone cultured at 17 or 25° C. Consequently, the are mechanisms of regulation of activity of the clones #28 and #29 had the same serotype at both surface protein genes that ensure their expression temperatures. Such type of cross-reactions has been according to the principle of mutual exclusion, as described in Paramecium. well as a tendency of some established serotype to When discussing the nature of cross-reactions be inherited in a series of cell generations. These of antisera with heterologous D. anser subclones issues have been the subjects of numerous studies that were cultured at different temperatures and (see Bleyman, 1996). comparing our results with the available literature A set of D. anser clones was used in our expe- data, we suggest that the incidence of cross-reactions riments. Immune sera (ISs) were obtained by immu- can be explained in two ways. First, serotype of #28 nizing rabbits with cell homogenate prepared from and #29 clones, which is detected at both 17 and 25° mass culture of a corresponding clone. Each of such C, may be determined by a single i-antigen related to ISs was considered to be homologous to the cells “warm” and “cold” serotypes of #5D, but manifests used for immunization and heterologous to the itself in a wider range of temperatures. Another cells of all other clones. At first, ISs were obtained possibility is that, contrary to the principle of mutual against two different clones of dilepti. Like other exclusion, cells of #28 and #29 clones synthesize well-studied representatives of ciliates (Paramecium two different antigens, which are simultaneously and Tetrahymena), dilepti demonstrated good ability expressed at both temperatures (Uspenskaya and to induce the formation of specific antibodies after Yudin, 1992). Under constant conditions, serotype immunization of rabbits with cells of a certain clone of dilepti remained unchanged in a great number of ciliates. Both ISs were characterized by high of agamic cell generations. When testing the above titers and caused characteristic immobilization clones a year and a few years later, there was almost reaction when applied to the homologous cells, 100% immobilization of cells with homologous sera thus showing the association of the IS specificity and the lack of cell response to heterologous sera. with a given i-antigen. Such reactions have been Testing other clones that had further enriched the described in Paramecia and Tetrahymena many laboratory collection revealed only 2–3 additional times (reviews: Beale, 1954, 1957). Using two cases of cross-reactions. antisera, the serotypes of 20 Dileptus clones of So, the use of even a small number of ISs different origin were identified. Totally, 38 hete- revealed wide polymorphism of serotypes in natural rologous “cell-to-serum” combinations were tested populations of D. anser, and this polymorphism Protistology · 63 was maintained during long-term cultivation under the differences between B and D serotypes was constant conditions. To investigate the inheritance unknown. In the simplest case, this difference of serotypes in D. anser during sexual processes, we could be for just one locus (allelic differences) or used two clones, #B and #D, grown from individuals for two different loci. The absence of any serological independently isolated from nature. These clones cross-reactions between B and D clones indicates belonged to a complementary mating types I significant immunological differences between the and III, actively conjugated and showed no cross corresponding i-antigens. This might be an evidence reaction when tested by immobilizing cells with of nonallelic nature of the respective serotypes. antisera, i.e. showed two different, clearly distinct Phenotype in F1 clones was certainly “hybrid”. If B serotypes that were stably maintained under the and D serotypes are allelic, then we are dealing with same culture conditions. ISs were obtained against co-expression of the corresponding alleles; if they these clones. Thereafter, their crossing was made. are non-allelic, then in D. anser there is a violation Cells of one of the two clones were labeled with of the principle of mutual exclusion of different loci Indian ink for precise identification and selection of controlling surface i-antigens. This challenge could heterotypic pairs. In a paired state the cells were for be resolved by receiving F2 progeny and analyzing 20–22 h, and exconjugants were isolated and grown. the segregation of studied traits. When testing Unfortunately, it was impossible to see the label in exconjugant F1 clones for their mating types, it was the isolated exconjugants in order to identify their found that most of the survivors were fully mature “cytoplasmic” origin. and belonged to mating type II. For this reason, to Exconjugant F1 clones were tested for cell obtain further F2 progeny, the F1 clones were mated immobilization reaction using ISs raised against with each of the “parent” clones (backcrossing).
Load more

Recommended publications
  • Pusillus Poseidon's Guide to Protozoa
    Pusillus Poseidon’s guide to PROTOZOA GENERAL NOTES ABOUT PROTOZOANS Protozoa are also called protists. The word “protist” is the more general term and includes all types of single-celled eukaryotes, whereas “protozoa” is more often used to describe the protists that are animal-like (as opposed to plant-like or fungi-like). Protists are measured using units called microns. There are 1000 microns in one millimeter. A millimeter is the smallest unit on a metric ruler and can be estimated with your fingers: The traditional way of classifying protists is by the way they look (morphology), by the way they move (mo- tility), and how and what they eat. This gives us terms such as ciliates, flagellates, ameboids, and all those colors of algae. Recently, the classification system has been overhauled and has become immensely complicated. (Infor- mation about DNA is now the primary consideration for classification, rather than how a creature looks or acts.) If you research these creatures on Wikipedia, you will see this new system being used. Bear in mind, however, that the categories are constantly shifting as we learn more and more about protist DNA. Here is a visual overview that might help you understand the wide range of similarities and differences. Some organisms fit into more than one category and some don’t fit well into any category. Always remember that classification is an artificial construct made by humans. The organisms don’t know anything about it and they don’t care what we think! CILIATES Eats anything smaller than Blepharisma looks slightly pink because it Blepharisma itself, even smaller Bleph- makes a red pigment that senses light (simi- arismas.
    [Show full text]
  • A Preliminary Survey on the Planktonic Biota in a Hypersaline Pond of Messolonghi Saltworks (W
    diversity Article A Preliminary Survey on the Planktonic Biota in a Hypersaline Pond of Messolonghi Saltworks (W. Greece) George N. Hotos Plankton Culture Laboratory, Department of Animal Production, Fisheries & Aquaculture, University of Patras, 30200 Messolonghi, Greece; [email protected] Abstract: During a survey in 2015, an impressive assemblage of organisms was found in a hypersaline pond of the Messolonghi saltworks. The salinity ranged between 50 and 180 ppt, and the organisms that were found fell into the categories of Cyanobacteria (17 species), Chlorophytes (4 species), Diatoms (23 species), Dinoflagellates (1 species), Protozoa (40 species), Rotifers (8 species), Copepods (1 species), Artemia sp., one nematode and Alternaria sp. (Fungi). Fabrea salina was the most prominent protist among all samples and salinities. This ciliate has the potential to be a live food candidate for marine fish larvae. Asteromonas gracilis proved to be a sturdy microalga, performing well in a broad spectrum of culture salinities. Most of the specimens were identified to the genus level only. Based on their morphology, as there are no relevant records in Greece, there is a possibility for some to be either new species or strikingly different strains of certain species recorded elsewhere. Keywords: protists; cyanobacteria; rotifers; crustacea; hypersaline conditions; Messolonghi saltworks 1. Introduction Citation: Hotos, G.N. A Preliminary It is well known that saltwork waters support high algal densities due to the abun- Survey on the Planktonic Biota in a dance of nutrients concentrated by evaporation [1–3]. Apart from the fact that such Hypersaline Pond of Messolonghi ecosystems are of paramount ecological value, they are also a potential source for tolerant Saltworks (W.
    [Show full text]
  • Systematic Index
    Systematic Index The systematic index contains the scientific names of all taxa mentioned in the book e.g., Anisonema sp., Anopheles and the vernacular names of protists, for example, tintinnids. The index is two-sided, that is, species ap - pear both with the genus-group name first e.g., Acineria incurvata and with the species-group name first ( incurvata , Acineria ). Species and genera, valid and invalid, are in italics print. The scientific name of a subgenus, when used with a binomen or trinomen, must be interpolated in parentheses between the genus-group name and the species- group name according to the International Code of Zoological Nomenclature. In the following index, these paren - theses are omitted to simplify electronic sorting. Thus, the name Apocolpodidium (Apocolpodidium) etoschense is list - ed as Apocolpodidium Apocolpodidium etoschense . Note that this name is also listed under “ Apocolpodidium etoschense , Apocolpodidium ” and “ etoschense , Apocolpodidium Apocolpodidium ”. Suprageneric taxa, communities, and vernacular names are represented in normal type. A boldface page number indicates the beginning of a detailed description, review, or discussion of a taxon. f or ff means include the following one or two page(s), respectively. A Actinobolina vorax 84 Aegyriana paroliva 191 abberans , Euplotes 193 Actinobolina wenrichii 84 aerophila , Centropyxis 87, 191 abberans , Frontonia 193 Actinobolonidae 216 f aerophila sphagnicola , Centropyxis 87 abbrevescens , Deviata 140, 200, 212 Actinophrys sol 84 aerophila sylvatica
    [Show full text]
  • Some Observations on Regeneration in Dileptus Anser
    Proceedings of the Iowa Academy of Science Volume 63 Annual Issue Article 71 1956 Some Observations on Regeneration in Dileptus Anser Paul A. Meglitsch Drake University Thomas Johnson Drake University Let us know how access to this document benefits ouy Copyright ©1956 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Meglitsch, Paul A. and Johnson, Thomas (1956) "Some Observations on Regeneration in Dileptus Anser," Proceedings of the Iowa Academy of Science, 63(1), 634-638. Available at: https://scholarworks.uni.edu/pias/vol63/iss1/71 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact [email protected]. Meglitsch and Johnson: Some Observations on Regeneration in Dileptus Anser Some Observations on Regeneration in Dileptus Anser By PAUL A. MEGLITSCH AND THOMAS JoHNSON One of the most interesting capacities of protozoans is their ability to replace lost parts following injury. Although they are structurally the equivalent of cells they are functional organisms, and a study of their behavior makes it possible to bring together concepts usually applied in the cellular field with those applied in the analysis of whole organisms. The same factors that operate to evoke a particular form in the whole organism must act in a small regenerating piece of a protozoan. Whether these factors are nuclear genes or protoplasmic organization, they act rapidly in the regenerating animal, regulating the form of the piece.
    [Show full text]
  • Lobban & Schefter 2008
    Micronesica 40(1/2): 253–273, 2008 Freshwater biodiversity of Guam. 1. Introduction, with new records of ciliates and a heliozoan CHRISTOPHER S. LOBBAN and MARÍA SCHEFTER Division of Natural Sciences, College of Natural & Applied Sciences, University of Guam, Mangilao, GU 96923 Abstract—Inland waters are the most endangered ecosystems in the world because of complex threats and management problems, yet the freshwater microbial eukaryotes and microinvertebrates are generally not well known and from Guam are virtually unknown. Photo- documentation can provide useful information on such organisms. In this paper we document protists from mostly lentic inland waters of Guam and report twelve freshwater ciliates, especially peritrichs, which are the first records of ciliates from Guam or Micronesia. We also report a species of Raphidiophrys (Heliozoa). Undergraduate students can meaningfully contribute to knowledge of regional biodiversity through individual or class projects using photodocumentation. Introduction Biodiversity has become an important field of study since it was first recognized as a concept some 20 years ago. It includes the totality of heritable variation at all levels, including numbers of species, in an ecosystem or the world (Wilson 1997). Biodiversity encompasses our recognition of the “ecosystem services” provided by organisms, the interconnectedness of species, and the impact of human activities, including global warming, on ecosystems and biodiversity (Reaka-Kudla et al. 1997). Current interest in biodiversity has prompted global bioinformatics efforts to identify species through DNA “barcodes” (Hebert et al. 2002) and to make databases accessible through the Internet (Ratnasingham & Hebert 2007, Encyclopedia of Life 2008). Biodiversity patterns are often contrasted between terrestrial ecosystems, with high endemism, and marine ecosystems, with low endemism except in the most remote archipelagoes (e.g., Hawai‘i), but patterns in Oceania suggest that this contrast may not be so clear as it seemed (Paulay & Meyer 2002).
    [Show full text]
  • Minimal Selfhood and the Origins of Consciousness
    ness In MinimalSelfhood andthe OriginsofConsciousness, ous R.D.V. Glasgowseeks to ground thelogical rootsof ci consciousness in what he haspreviouslycalled the ns ‘minimal self’. Th eideaisthatelementary forms Co of consciousness arelogicallydependent not, as is of ns commonly assumed, on ownershipofananatomical i brainornervous system, but on theintrinsic reflexi- rig vity that definesminimal selfhood. Theaim of the eO bookistotracethe logical pathwaybywhich mini- th malselfhood givesrisetothe possible appearance of consciousness.Itisarguedthatinspecificcircum- and R.D.V. Glasgow stancesitthusmakes sensetoascribe elementary ood consciousness to certain predatorysingle-celled or- ganismssuchasamoebae anddinoflagellatesaswell elfh as to some of thesimpler animals. Such an argument lS involves establishingexactlywhatthose specific ima circumstances areand determining howelementary Min consciousness differsinnatureand scopefrom its more complex manifestations. sgow la .G R.D.V Würzburg University Press ISBN 978-3-95826-078-8 Rupert D.V. Glasgow Minimal Selfhood and the Origins of Consciousness Rupert D.V. Glasgow Minimal Selfhood and the Origins of Consciousness Impressum Julius-Maximilians-Universität Würzburg Würzburg University Press Universitätsbibliothek Würzburg Am Hubland D-97074 Würzburg www.wup.uni-wuerzburg.de ©2018 Würzburg University Press Print on Demand Coverdesign & Illustrationen: Christina Nath ISBN: 978-3-95826-078-8 (print) ISBN: 978-3-95286-079-5 (online) URN: urn:nbn:de:bvb:20-opus-157470 Except otherwise noted, this document – excluding the cover – is licensed under the Creative Commons License Attribution-ShareAlike 4.0 International (CC BY-SA 4.0): https://creativecommons.org/licenses/by-sa/4.0/ The cover page is licensed under the Creative Commons License Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0): http://creativecommons.org/licenses/by-nc-nd/4.0/ Acknowledgements The present book originally formed a rather long final chapter of a PhD dissertation entitled The Minimal Self.
    [Show full text]
  • Description of Four New Soil Dileptids (Ciliophoru) Haptoria), with Notes on Adaptations to the Soil Environment
    Acta Protozool (2008) 47: 2lI-230 AGTA PRtlltlZOtlTtlGIGA Description of Four New Soil Dileptids (Ciliophoru) Haptoria), with Notes on Adaptations to the Soil Environment Peter VüAÖNfr,2 and Wilhelm FOISSNER1 lUniversität Salzburg, FB Organismische Biologie, Salzburg, Austria; 2Comenius University, Department of Zoology, Bratislava, Slovak Republic Summary. We studied the morphology of four new dileptid ciliates, using standard methods. Dileptus microstoma, which was discovered in Benin (Africa), is outstanding in having a very small oral opening (-4 pm), an intemrpted dorsal row of contractile vacuoles, and ampul- liform extrusomes. Dileptus semiarmatus, which was discovered in Austria, possesses extrusomes only in the right posterior half of the pro- boscis and has very widely spaced circumoral and perioral kinetids. Dileptus longitrichus, which was discovered in Japan, is almost unique in having up to 15pm long brush bristles and a row of contractile vacuoles each in ventral and dorsal side of body. Pseudomonilicaryon brachyproboscrs, which was discovered in Greece, differs from the congeners by the narrowly ellipsoidal micronuclei, the dimorphic dorsal brush, the extrusomes, and the contractile vacuole pattern. Four new features are introduced for distinguishing species in dileptids: shape of micronucleus, monomorphic/dimorphic dorsal brush, shape of oral opening, and spacing of circumoral dikinetids. The terrestrial dileptids share several distinct morphological features that are probably adaptations to the soil environment: (1) the body is comparatively slender and small, what is likely related to the narrowness of the habitat; (2) the proboscis is short, which increases the relative volume of the trunk, what might be related to its fragility and,/or to the space available for prey digestion; (3) the long dorsal bristles might foster prey recognition; and (4) the pronounced body flexibility in all dileptids likely fosters their high diversity in the narrow and wrinkled soil habitat.
    [Show full text]
  • Cultivation of Marine Ciliates (Tintinnida) and Heterotrophic Flagellates:"
    Helgol~inder wiss. Meeresunters. 20, 264-271 (1970) Cultivation of marine ciliates (Tintinnida) and heterotrophic flagellates:" K. GOLD Osborn Laboratories of Marine Sciences; Brooklyn, N. Y., USA KURZFASSUNG: Kultur mariner Ciliaten (Tintinnida) und heterotropher Flagellaten. Fol- gende heterotrophe Protozoen sind mit Erfolg in Kultur genommen worden: Tintinnopsis beroidea (Tintinnida), Cryptothecodiniurn cohnii und Noctiluca scintillans (Dinoflagellata), Diaphanoeca grandis und Acanthoecopsis sp. (Choanoflagellata). Angaben fiber Isolierung, Kul- turtechnik und Erniihrung sowie einige diese Arten betreffende biologische Daten werden mitgeteilt. INTRODUCTION A challenge to ecologists during the next decade lies in cultivation of a greater variety of marine heterotrophic protozoans than is presently available for study. This group comprises both osmotrophic and holozoic organisms that are markedly affected by the content and quality of organic substances in sea water, and/or the composition of the particulate fraction. Many are known to have high metabolic rates and rapid generation times (PAvLOVSKAYA1969), thus making their roles as grazers and nutrient regenerators worthy of greater consideration. Cultivation of representative species will afford the opportunity to examine their requirements in vitro, as one way to evaluate their impact on the marine environment. This paper describes the heterotrophic Protozoa that are presently under in- vestigation in this laboratory, and outlines their nutritional status and some potential applications. MATERIALS AND METHODS The heterotrophic species presently under investigation in this laboratory are: Tintinnopsis beroidea (several strains), Cryptothecodinium cohnii, Noctiluca scin- tillans, Diaphanoeca grandis, and Acanthoecopsis sp. Other species that were cultured and which contributed to an understanding of the Tintinnida were: T. tubulosa (GOLD * Supported by a contract with the U.S.
    [Show full text]
  • Protistology Serotypes in the Ciliate Dileptus Anser: Epigenetic
    Protistology 2 (3), 142–151 (2002) Protistology Serotypes in the ciliate Dileptus anser: epigenetic phenomena Alexander L. Yudin and Zoya I. Uspenskaya Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia Summary This review presents some data obtained by the authors in their study of the serotype system in the lower ciliate Dileptus anser, a species that has not been explored previously in this aspect. These data show many features similar to those described in serotype systems of higher ciliates, Paramecium and Tetrahymena. At the same time, some of the results do not agree with conventional patterns generally accepted for these classical objects. The authors discuss the data obtained in dilepti in terms of epigenetic variation and inheritance. Key words: ciliates, Dileptus anser, serotypes, immobilization antigens, nonMendelian inheritance, serotype transformation, regulation of serotype expression, epigenetic variation and inheritance In the ciliates Paramecium and Tetrahymena, their at any one time, only one iantigen is detectable on the serotype systems have long been studied and were cell surface of all genotypically available antigens. In a revealed to have a diversity of peculiar properties. number of cases, this rule is followed not only by The ciliate serotype is principally defined through different genes, but also by different alleles of the same the use of immunological techniques and depends on a gene. Exceptional cases (in which two or more i certain class of proteins distributed all over the surface antigens are revealed simultaneously on the cell surface) of the external cell membrane and cilia (Beale and Mott, occur very seldom. When cultural conditions are 1962; Doerder, 1981).
    [Show full text]
  • Regulation of Ciliary Pattern in Dileptus (Ciliata). I. Sensory Cilia and Their Conversion Into Locomotor Cilia
    /. Embryol exp. Morph. Vol. 68, pp. 99-114, 1982 99 Printed in Great Britain © Company of Biologists Limited 1982 Regulation of ciliary pattern in Dileptus (Ciliata). I. Sensory cilia and their conversion into locomotor cilia By KRYSTYNA GOLINSKA1 From the Nencki Institute of Experimental Biology, Department of Cell Biology, Warsaw SUMMARY The surface of Dileptus contains three different regions: locomotor, oral and sensory. Each region has cilia with a specific structure and arranged in a characteristic pattern. In the morphogenetic situation when a sensory region transforms into a locomotor one, sensory cilia undergo structural changes converting them into locomotor cilia. The evidence for this is that cilia are found in the transforming region with an inner microtubular pattern inter- mediate between that of sensory and locomotor cilia. There are also changes in distribution of sensory units leading to a pattern characteristic of locomotor cilia. The conversion of sensory cilia into locomotor ones is also confirmed by a complete lack of evidence for resorption of sensory units within the transforming region, although the resorption is usually very easily observed with the transmission electron microscope. Transformation lasts about 5 h after the operation; afterwards locomotor cilia of normal appearance occupy the trans- formed region. This way of regulation of ciliary pattern has not been previously described. Its most surprising feature is the regulation of inner structure in an already differentiated ciliary unit. Some aspects of mechanisms which could control this kind of pattern regulation,! are discussed. INTRODUCTION The surface of a ciliate cell is usually subdivided into several cortical territories where ciliary structures have an organization characteristic of the region.
    [Show full text]
  • Responses of Intermittent Pond Ciliate Populations and Communities to in Situ Bottom-Up and Top-Down Manipulations
    AQUATIC MICROBIAL ECOLOGY Vol. 42: 293–310, 2006 Published March 29 Aquat Microb Ecol Responses of intermittent pond ciliate populations and communities to in situ bottom-up and top-down manipulations Oksana P. Andrushchyshyn, A. Katarina Magnusson, D. Dudley Williams* Surface and Groundwater Ecology Research Group, Department of Life Sciences, University of Toronto at Scarborough, 1265 Military Trail, Ontario M1C 1A4, Canada ABSTRACT: Pond physicochemical characteristics and bottom-up effects were more important than top-down effects in governing ciliate community structure in 2 adjacent intermittent ponds in South- ern Ontario, Canada. The ciliates showed a bimodal seasonal pattern with abundances peaking early and late in the hydroperiods, and the communities showed a strong seasonal succession of species — only 15% of the 162 ciliate species were present throughout the hydroperiods. Less than half of the species occurred in both ponds. Adding riparian leaf litter to large pond enclosures affected several physicochemical variables, increased bacterial abundance, and promoted the appearance of particu- lar species — many of which are known to be associated with nutrient- or organic matter-enriched conditions. This treatment resulted in higher ciliate abundance (mainly small-sized bacterivores) and lower ciliate diversity in mid-hydroperiod in one of the ponds. The removal of plant litter generally produced effects in the physicochemical variables that were opposite to those seen in the leaf litter addition, and resulted in a 15% decrease in the proportion of ciliate bacterivores in one pond. The effects of top-down manipulations (i.e. prevention of aerial colonization of insects) were minor. Many treatment effects were season-, and pond-specific.
    [Show full text]
  • Protistology Fine Structure of Nucleoli in the Ciliate Didinium Nasutum*
    Protistology 3 (2), 99-106 (2003) Protistology Fine structure of nucleoli in the ciliate Didinium nasutum* Bella P. Karajan1, Vladimir I. Popenko2 and Olga G. Leonova2 1 Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, 194064 St. Petersburg, Russia 2 Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, 119991 Moscow, Russia Summary The macronuclear nucleoli of vegetative non-dividing cells of Didinium nasutum display inverted position of the main parts: the granular component is inside and the dense fibrillar one, in form of discrete bands, is mainly at the periphery. Before binary fission, the nucleoli are degranulated and their fibrillar bands scatter throughout the macronucleus, to be segregated during division between the daughter cells, where they begin to re-form the granular parts. In young resting cysts small nucleoli consist of granular material only, larger nucleoli show a clear segregation of its fibrillar and granular elements. During conjugation, nucleoli of the old macronucleus or of its fragments become segregated into granular and fibrillar parts and the latter are largely eliminated. The nucleoli lose contact with the chromatin bodies. In the developing anlagen of the new macronuclei the first nucleoli appear as fibrous bodies and only later develop granular parts; simultaneously the number of nucleoli increases. Key Words: macronucleus, nucleoli, cell cycle, cysts, Didinium nasutum 1995). The organization of rDNA in gymnostomes, Introduction including Didinium, is not
    [Show full text]