Ultrastructural features of the tomont of Cryptocaryon irritans (Ciliophora: Prostomatea), a parasitic ciliate of marine fishes

Parasitology ◽  
2017 ◽  
Vol 144 (6) ◽  
pp. 720-729 ◽  
Author(s):  
RUI MA ◽  
XINPENG FAN ◽  
FEI YIN ◽  
BING NI ◽  
FUKANG GU
Keyword(s):  
Cell Division ◽  
Cyst Wall ◽  
Light And Electron Microscopy ◽  
Secretory Vesicles ◽  
Free Living ◽  
Cryptocaryon Irritans ◽  
Daughter Cells ◽  
Molecular Events ◽  
Cellular Metabolic Activity ◽  
Cellular Organelles

SUMMARYNumerous studies have been conducted on the cellular morphology of Cryptocaryon irritans. However, details regarding the tomont stage of its life cycle remain lacking. In this study, we investigated the morphology of the tomont stage throughout encystment and cell division using light and electron microscopy. Results showed that there was no secretion of encystation-specific secretory vesicles or extrusomes during formation of the cyst wall. Instead, the synthesis and construction of the C. irritans cyst wall materials may involve molecular events at the pellicle. The somatic cilia and the cytostome were present during encystment and covered by the newly formed cyst wall. New somatic cilia were continuously created between old cilia and showed various lengths during cell division, a process that was similar to morphogenesis in many free-living ciliates. During cell division inside the tomont, dividing daughter cells formed temporary cell chains with no oral primordia before separating from each other into dissociative tomite precursors. The process of cell division may not be accompanied by stomatogenesis, and new oral primordia in offspring cells likely formed before the dividing cell chains split into dissociative spherical tomites. Mitochondrial autophagy was observed in encysting C. irritans cells. Numerous endosymbionts and Golgi structures were observed in the tomont cytoplasm. Cellular metabolic activity in the C. irritans tomont was quite high, with large amounts of materials or cellular organelles potentially being synthesized and prepared for the following infective theront stage.

Ultrastructure observation on the cells at different life history stages of Cryptocaryon irritans (Ciliophora: Prostomatea), a parasitic ciliate of marine fishes

Parasitology ◽  
2016 ◽  
Vol 143 (11) ◽  
pp. 1479-1489 ◽  
Author(s):  
RUI MA ◽  
BING NI ◽  
XINPENG FAN ◽  
ALAN WARREN ◽  
FEI YIN ◽  
...  
Keyword(s):  
Life History ◽  
Light And Electron Microscopy ◽  
Fish Tissue ◽  
Ultrastructural Level ◽  
Marine Fishes ◽  
Host Fish ◽  
Free Living ◽  
Cryptocaryon Irritans ◽  
Life History Stages ◽  
First Time

SUMMARYCells of Cryptocaryon irritans at different life history stages were studied using both light and electron microscopy. The characteristics of several organelles were revealed for the first time at the ultrastructural level. It was confirmed that the cytostome of trophonts, protomonts and theronts was surrounded by cilium–palp triplets rather than ciliary triplets. The nematodesmata underlying the circumoral dikinetids were single bundles, whereas these were always paired in Prorodontids. Toxicysts were present in late-stage tomonts and theronts, but were absent in trophonts and protomonts. We posited that toxicysts might play a role in infection and invasion of host-fish tissue by theronts. The adoral brosse was unlike that of any other family of the class Prostomatea based on its location and morphology. Membranous folds were present in trophonts, protomonts and theronts. These folds were longer and more highly developed in C. irritans than in exclusively free-living prostome ciliates suggesting that they might be linked to parasitism in C. irritans. Trophonts, protomonts and theronts had multiple contractile vacuoles. The basic ultrastructure of the contractile vacuole of C. irritans was similar to that of other kinetofragminophoran ciliates. They might play different roles in different stages of the life cycle since their ultrastructure varied among trophonts, protomonts and theronts.

Stimulated Virus Production in Vinblastine and Cytochalasin-Induced Multinucleate Cells

1970 ◽  
Vol 28 ◽  
pp. 186-187
Author(s):  
Krishan Awtar
Keyword(s):  
Cell Division ◽  
Normal Cell ◽  
Virus Production ◽  
Multinucleate Cells ◽  
Daughter Cells ◽  
Cell Divisions ◽  
Nuclear Membranes ◽  
Division 2 ◽  
Vinblastine Sulfate

Exposure of cells to low sublethal but mitosis-arresting doses of vinblastine sulfate (Velban) results in the initial arrest of cells in mitosis followed by their subsequent return to an “interphase“-like stage. A large number of these cells reform their nuclear membranes and form large multimicronucleated cells, some containing as many as 25 or more micronuclei (1). Formation of large multinucleate cells is also caused by cytochalasin, by causing the fusion of daughter cells at the end of an otherwise .normal cell division (2). By the repetition of this process through subsequent cell divisions, large cells with 6 or more nuclei are formed.

Encystment and germination of the parasitic chytrid Rozella allomycis on host hyphae

1973 ◽  
Vol 51 (10) ◽  
pp. 1825-1835 ◽  
Author(s):  
Abraham A. Held
Keyword(s):  
Cyst Wall ◽  
Germ Tube ◽  
Light And Electron Microscopy ◽  
Multivesicular Bodies ◽  
Cell Periphery ◽  
General Sequence ◽  
Obligate Intracellular ◽  
Host Cytoplasm ◽  
Intracellular Parasites ◽  
Three Stages

Zoospores of the obligately parasitic chytrid Rozella allomycis which settle upon hyphae of the water mold host, Allomyces arbuscula, encyst and germinate before their protoplasts penetrate into the host cytoplasm. This process has been examined by light and electron microscopy. Three stages which follow the attachment to the host and the retraction of the zoospore's flagellum are described: (1) the early cyst lacks a wall; it is discoid, and its shape is maintained by the coil of the retracted axoneme which forms its rim; (2) a cyst wall is formed while multivesicular bodies occur at the cell periphery and eventually disappear; a germ tube starts to grow at the point of attachment; and (3) the firm-walled cyst is spheroidal; it has a fully developed germ tube with a specialized class of vesicles; it also forms a distal, flattened vacuole whose swelling eventually injects the Rozella protoplast into the host; at this stage the retracted axoneme has disappeared and the cell's organelles have undergone extensive changes. Electron-dense, "gamma-like" granules enclosed in vacuoles may play a major role in the formation of both the cyst wall and the distal vacuole. These granules appear to give rise to small vesicles, and thus to multivesicular bodies; the distal vacuole appears to form by coalescense of gamma-like vacuoles.The general sequence of encystment and germination resembles that found in other Chytridiomycetes, both saprophytic and parasitic. However, the distal vacuole and the vesicles in the germ tube appear to be parasitic adaptations and are shared by obligate intracellular parasites from several unrelated groups of zoosporic fungi.

scholarly journals A complex containing the Sm protein CAR-1 and the RNA helicase CGH-1 is required for embryonic cytokinesis in Caenorhabditis elegans

2005 ◽  
Vol 171 (2) ◽  
pp. 267-279 ◽  
Author(s):  
Anjon Audhya ◽  
Francie Hyndman ◽  
Ian X. McLeod ◽  
Amy S. Maddox ◽  
John R. Yates ◽  
...  
Keyword(s):  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Rna Binding ◽  
Rna Binding Protein ◽  
Rna Helicase ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Daughter Cells ◽  
Sm Protein ◽  
Spindle Structure

Cytokinesis completes cell division and partitions the contents of one cell to the two daughter cells. Here we characterize CAR-1, a predicted RNA binding protein that is implicated in cytokinesis. CAR-1 localizes to germline-specific RNA-containing particles and copurifies with the essential RNA helicase, CGH-1, in an RNA-dependent fashion. The atypical Sm domain of CAR-1, which directly binds RNA, is dispensable for CAR-1 localization, but is critical for its function. Inhibition of CAR-1 by RNA-mediated depletion or mutation results in a specific defect in embryonic cytokinesis. This cytokinesis failure likely results from an anaphase spindle defect in which interzonal microtubule bundles that recruit Aurora B kinase and the kinesin, ZEN-4, fail to form between the separating chromosomes. Depletion of CGH-1 results in sterility, but partially depleted worms produce embryos that exhibit the CAR-1–depletion phenotype. Cumulatively, our results suggest that CAR-1 functions with CGH-1 to regulate a specific set of maternally loaded RNAs that is required for anaphase spindle structure and cytokinesis.

Nucleologenesis in Trypanosoma cruzi

2016 ◽  
Vol 22 (3) ◽  
pp. 621-629 ◽  
Author(s):  
Tomás Nepomuceno-Mejía ◽  
Reyna Lara-Martínez ◽  
Roberto Hernández ◽  
María de Lourdes Segura-Valdez ◽  
Luis F. Jiménez-García
Keyword(s):  
Cell Division ◽  
Trypanosoma Cruzi ◽  
Ethylenediaminetetraacetic Acid ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Light And Electron Microscopy ◽  
Nucleolar Organizer ◽  
Nuclear Bodies ◽  
Nucleolar Organizer Regions ◽  
Nucleolar Material

AbstractNucleolar assembly is a cellular event that requires the synthesis and processing of ribosomal RNA, in addition to the participation of pre-nucleolar bodies (PNBs) at the end of mitosis. In mammals and plants, nucleolar biogenesis has been described in detail, but in unicellular eukaryotes it is a poorly understood process. In this study, we used light and electron microscopy cytochemical techniques to investigate the distribution of nucleolar components in the pathway of nucleolus rebuilding during closed cell division in epimastigotes of Trypanosoma cruzi, the etiologic agent of American trypanosomiasis. Silver impregnation specific for nucleolar organizer regions and an ethylenediaminetetraacetic acid regressive procedure to preferentially stain ribonucleoprotein revealed the conservation and dispersion of nucleolar material throughout the nucleoplasm during cell division. Furthermore, at the end of mitosis, the argyrophilic proteins were concentrated in the nucleolar organizer region. Unexpectedly, accumulation of nucleolar material in the form of PNBs was not visualized. We suggest that formation of the nucleolus in epimastigotes of T. cruzi occurs by a process that does not require the concentration of nucleolar material within intermediate nuclear bodies such as mammalian and plant PNBs.

scholarly journals Dem Anfang auf der Spur — die Suche nach DNA-Replikationsursprüngen

BIOspektrum ◽  
2021 ◽  
Vol 27 (3) ◽  
pp. 246-249
Author(s):  
Elisabeth Kruse ◽  
Stephan Hamperl
Keyword(s):  
Cell Division ◽  
Dna Synthesis ◽  
Genomic Dna ◽  
Genetic Material ◽  
Uniform Method ◽  
Replication Origins ◽  
Daughter Cells ◽  
Origins Of Replication ◽  
Mammalian Genomes ◽  
Comprehensive Manner

AbstractTimely and accurate duplication of DNA prior to cell division is a prerequisite for propagation of the genetic material to both daughter cells. DNA synthesis initiates at discrete sites, termed replication origins, and proceeds in a bidirectional manner until all genomic DNA is replicated. Despite the fundamental nature of these events, a uniform method that identifies origins of replication in a comprehensive manner is still missing. Here, we present currently available and discuss new approaches to map replication origins in mammalian genomes.

Effects of excess centromeres and excess telomeres on chromosome loss rates

1991 ◽  
Vol 11 (6) ◽  
pp. 2919-2928
Author(s):  
K W Runge ◽  
R J Wellinger ◽  
V A Zakian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Dna Sequences ◽  
Fluctuation Analysis ◽  
Chromosome Stability ◽  
Chromosome Loss ◽  
Division Iii ◽  
Daughter Cells ◽  
Chromosome Iii ◽  
Linear Chromosomes

The linear chromosomes of eukaryotes contain specialized structures to ensure their faithful replication and segregation to daughter cells. Two of these structures, centromeres and telomeres, are limited, respectively, to one and two copies per chromosome. It is possible that the proteins that interact with centromere and telomere DNA sequences are present in limiting amounts and could be competed away from the chromosomal copies of these elements by additional copies introduced on plasmids. We have introduced excess centromeres and telomeres into Saccharomyces cerevisiae and quantitated their effects on the rates of loss of chromosome III and chromosome VII by fluctuation analysis. We show that (i) 600 new telomeres have no effect on chromosome loss; (ii) an average of 25 extra centromere DNA sequences increase the rate of chromosome III loss from 0.4 x 10(-4) events per cell division to 1.3 x 10(-3) events per cell division; (iii) centromere DNA (CEN) sequences on circular vectors destabilize chromosomes more effectively than do CEN sequences on 15-kb linear vectors, and transcribed CEN sequences have no effect on chromosome stability. We discuss the different effects of extra centromere and telomere DNA sequences on chromosome stability in terms of how the cell recognizes these two chromosomal structures.

Cell division and morphogenesis of Limnaea eggs after treatment with heat pulses at successive stages in early division cycles

Development ◽  
1966 ◽  
Vol 16 (2) ◽  
pp. 321-337
Author(s):  
W. L. M. Geilenkirchen
Keyword(s):  
Cell Division ◽  
Produce Cell ◽  
Cleavage Cycle ◽  
Daughter Cells ◽  
Development And Differentiation ◽  
Heat Pulses

Cellular reproduction is related to a number of apparently independent processes of which the integrated results are bound to produce cell division. In eggs with determinate cleavage the results of division are daughter cells of a different prospective significance. It has been observed furthermore in Limnaea eggs that morphogenesis is related to periodically recurring cell activities in the first, second and third cleavage cycle (Geilenkirchen, 1964a, b). These activities of unknown nature are dissociable from the factors involved in cell division. Obviously in the course of one division cycle the egg discriminates between processes for the preparation of the next division and processes involved in morphogenesis and differentiation later on. The data published in this paper carry the notion that successive divisions represent well-defined steps of different significance for later development and differentiation.

scholarly journals Midbody: From the Regulator of Cytokinesis to Postmitotic Signaling Organelle

Medicina ◽  
2018 ◽  
Vol 54 (4) ◽  
pp. 53 ◽  
Author(s):  
Ieva Antanavičiūtė ◽  
Paulius Gibieža ◽  
Rytis Prekeris ◽  
Vytenis Skeberdis
Keyword(s):  
Stem Cells ◽  
Cell Division ◽  
Intercellular Bridge ◽  
Large Protein ◽  
Daughter Cells ◽  
First Case ◽  
Tumorigenic Potential ◽  
The One ◽  
And Function ◽  
Protein Rich

Faithful cell division is crucial for successful proliferation, differentiation, and development of cells, tissue homeostasis, and preservation of genomic integrity. Cytokinesis is a terminal stage of cell division, leaving two genetically identical daughter cells connected by an intercellular bridge (ICB) containing the midbody (MB), a large protein-rich organelle, in the middle. Cell division may result in asymmetric or symmetric abscission of the ICB. In the first case, the ICB is severed on the one side of the MB, and the MB is inherited by the opposite daughter cell. In the second case, the MB is cut from both sides, expelled into the extracellular space, and later it can be engulfed by surrounding cells. Cells with lower autophagic activity, such as stem cells and cancer stem cells, are inclined to accumulate MBs. Inherited MBs affect cell polarity, modulate intra- and intercellular communication, enhance pluripotency of stem cells, and increase tumorigenic potential of cancer cells. In this review, we briefly summarize the latest knowledge on MB formation, inheritance, degradation, and function, and in addition, present and discuss our recent findings on the electrical and chemical communication of cells connected through the MB-containing ICB.

Sign in / Sign up

Export Citation Format

Share Document