Cyrtolophosis elongata (colpodea ciliophora): Some aspects of ciliary pattern, division, cortical and nuclear changes during encystment and resting cyst ultrastructure (original) (raw)
Related papers
Cortical and Nuclear Events During Cell Division and Resting Cyst Formation in Colpoda inflata
The Journal of Protozoology, 1991
Nuclear and cortical phenomena during dividing and resting cyst formation of Colpoda inflata are described. Cell division forms a cyst and produces two or four tomites. In each tomite, the right oral field results from the proliferation of the anterior extreme of a single kinety, and the left oral field results from the proliferation of four, five, or six somatic kineties. After macronuclear division, each macronuclear mass undergoes a chromatinic extrusion process. During resting cyst formation, the oral infraciliature of the vegetative cell is resorbed. The somatic kineties dispose in a radial way and some pairs of kinetosomes disappear. As in cell division, there is an extrusion process. From these results we conclude that the resting cysts of Colpoda inflata cannot be included in any group of the previous classifications for hypotrich resting cysts. Thus, we propose a new additional group to Walker and Maugel's classification called PKR (partial-kinetosome-resorbing) cysts.
Morphological study on the encystment of the ciliated protozoan Colpoda cucullus
Morphological changes during resting cyst formation (encystment) of Colpoda cucullus were examined. At 1 hr after encystment induction, a number of vesicles containing the electron-dense and toluidine blue (TB) positive materials were fused with large vacuoles to excrete the contents, and the vacuoles opened to the extracellular space to excrete. In this stage, the rounded precystic cells were surrounded by the first-synthesized cyst wall layer (L1 layer), and the cilia were resorbed inside the L1 layer. Thereafter (1-2 hr), a secondary layer (L2 layer) was formed and subsequently a deeply TB stained substance was diffused into the space between the plasma membrane and L2 layer. At 3-6 hr, numerous endoplasmic reticula (ER) associated with ribosomes occupied the cytoplasm, indicating that cyst wall precursors such as glycoconjugates were being synthesized. By a week after encystment induction, the cyst wall composed of three distinct layers covered with a fibrous (mucous) coat was completed. The kinetosomes were still observed in 3-day old cysts.
Archiv für Protistenkunde, 1990
The variability of 2 Austrian populations (Gn, Bn), one Turkish (Tn) , and one Japanese population (In) of the hypotrich ciliate Engelmanniella mobilis (ENGELMANN, 1862) FOISSNER, 1982 is compared by morphological and morphogenetic analyses. These populations were isolated from soils and represent 2 groups (Gn, Bn, Tn; In) concerning some quantitative characters of the infraciliature, the morphology of the resting cyst, and some nuclear features during division. However, in cultures maintained for 3 months the variability of the Turkish population (Tc) increased markedly closing this gap. This demonstrates that morphological differences originating during cultivation might be greater than those observed in natural populations. The variability of our populations embraces E. halseyi (CALKINS, 1929) and E. mobilis americanus (KAHL, 1932), which thus fall as junior synonyms of E. mobilis. During division and physiological reorganization the cortical events are identical in all populations, while the micronuclear processes may be slightly modified. Divisional and reorganizational morphogenesis differ in the origin of the frontal anlagen. The characterization of Engelmanniella FOISSNER, 1982 is improved. Young resting cysts of Bn, Tn, and Tc are characterized by a mucus layer originating from the extruded subpellicular granules. This layer is absent in older cysts and in the resting cyst of the Japanese population, although the subpellicular granules are released too. Oxytrichid (4-layered cyst wall, fused macronuc1ear segments) and urostylid (cortical microtubules) characters are mixed up in the resting cyst of E. mobilis, Kahliella simplex, and Paraurosryla weissei suggesting that the proposed classification of hypotrich resting cysts is premature.
INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2009
The ciliate family Cyrtolophosididae Stokes, 1888 contains species that are poorly known from both the morphological and molecular perspectives. To further our understanding of this family, one species, Aristerostoma marinum Kahl, 1931, was redescribed. Cells in our population had a mean in vivo size of 15¾8 mm. There were six rows of somatic kineties, as well as six dorsal kinetids belonging to sparsely ciliated somatic kineties. The oral apparatus comprised a bipartite paroral membrane and four adoral organelles. The optimal ecological tolerances for pH and O 2 matched those of the environment in which the specimens were collected, but were different for salinity and temperature. To further test the phylogenetic placement of the family Cyrtolophosididae with increased taxon sampling, the small subunit rDNA of three morphospecies was characterized: A. marinum, Aristerostoma sp. ATCC 50986 and Pseudocyrtolophopsis alpestris. Unconstrained and constrained molecular analyses supported the non-monophyly of the order Cyrtolophosidida. The family Cyrtolophosididae fell out separately from the rest of its order. Haplotypes from previous environmental studies were also placed in a phylogenetic context within the class Colpodea.
Resting cysts: A survival strategy in Protozoa Ciliophora
Italian Journal of Zoology, 2011
Encystment is a reversible cell differentiation process that also requires an antagonistic process, i.e. excystment. Both processes are genetically encoded. Encystment is of common occurrence among free-living ciliates and may serve several different purposes. In some ciliates, this process is part of the regular life cycle (reproductive cyst), while many other ciliates undergo encystment when environmental conditions become adverse (resting cyst). In this review, the different phases and aspects of the encystment process in ciliates, such as the ecological role, the cyst formation, the morphological characteristics of the cysts and their dynamic state during the time and the excysting process are reviewed on the basis on our own results and literature data.
The Journal of Protozoology, 1987
The morphology and the morphogenesis of the freshwater hypotrich ciliate Onychodromus quadricornutus n. sp. have been investigated using living organisms, protargol impregnation, and scanning electron microscopy. Some preliminary and supplementary results about the morphogenesis of 0. grandis and Laurentiella acuminata are included. The new species is unique among all described hypotrichs in having four dorsal horns, whose function is unknown. In addition, 0. quadricornutus is probably the most voluminous hypotrich ciliate known (2 x 10b-5 x lo6 pm3). Its morphogenetic pattern resembles the oxytrichids 0. grandis and L. acuminata. The strongest apomorphic character, which unites these three species, is probably the multiple fragmentation of the dorsal primordia during morphogenesis. This fragmentation causes the characteristic high number and more or Iess irregular distribution of the dorsal kineties in the non-dividing individuals. YPOTRICHOUS ciliates have been well known for a long H time and were carefully studied by many authors; however, their classification remains controversial to date (5). The new species described is unique among all known hypotrichous ciliates in having horns and presents new data that may contribute to a deeper understanding of systematics and evolution of the family Oxytrichidae in the order Hypotrichida.
European Journal of Protistology, 2010
The survival of ciliate resting cysts, in the presence and absence of soil, was studied under two environmental stresses: desiccation and freezing. Laboratory strains of the common species Colpoda inflata and the rare species Meseres corlissi were used in these experiments, which yielded the following results: 1) Freezing of cysts in soil with a residual moisture level exceeding $30% was destructive for both species. 2) Survival of Meseres corlissi cysts depended largely on the presence of soil. 3) In the absence of soil, Colpoda inflata cysts had greater tolerance to desiccation and freezing than Meseres corlissi cysts. Possible consequences for the distribution of natural populations are discussed.
European Journal of Protistology, 2001
The macronucleus of Colpoda inflata was studied by image analysis to determine variations that occur in chromatin structure during excystment from resting cysts. Morphometric and densitometric parameters, 22 Markovian chromatin texture variables, and the presence of chromatin extrusion bodies were examined in 1-, 5-, and 10-day-old excysting cells. Marked variations in densitometric values and Markovian variables were found only in 1-day-old excysting cells, thus suggesting that the chromatin extrusion process, where not already accomplished in early encystment, is triggered by excystment. Comparative study of the mean light absorption histograms computed on optical microscopic images of excysting cells, derived from 2-and 25-day-old cysts of a standard culture and from 1-year-old cysts of a senescent culture, showed three and two classes of histograms, respectively, characterised by differently condensed chromatin. Moreover, as excystment progresses, the percentage of macronuclei with decondensed chromatin that also show an extrusion body of condensed chromatin increases, thus suggesting that the macronucleus is somehow renewed by extruding chromatin that is unable to decondense. This event appears as a possible mechanism responsable for the 'rejuvenescence' of senescent cell lines.