Incomplete Inhibition of Synchronized Cell Division by Hydroxyurea and its Relevance to the Normal Cellular Life Cycle

Nature ◽  
1967 ◽  
Vol 216 (5119) ◽  
pp. 1017-1018 ◽  
Author(s):  
J. E. BYFIELD ◽  
O. H. SCHERBAUM
Keyword(s):  
Life Cycle ◽  
Cell Division ◽  
Cellular Life

The logic of cell division in the life cycle of yeast

Science ◽  
1992 ◽  
Vol 257 (5070) ◽  
pp. 626-626 ◽  
Author(s):  
C. Gimeno ◽  
G. Fink
Keyword(s):  
Life Cycle ◽  
Cell Division

scholarly journals Plasmodium Kinesin-8X associates with mitotic spindles and is essential for oocyst development during parasite proliferation and transmission

2019 ◽  
Author(s):  
Mohammad Zeeshan ◽  
Fiona Shilliday ◽  
Tianyang Liu ◽  
Steven Abel ◽  
Tobias Mourier ◽  
...  
Keyword(s):  
Life Cycle ◽  
Cell Division ◽  
Gene Targeting ◽  
Intracellular Transport ◽  
Regulation Of Gene Expression ◽  
Microtubule Depolymerization ◽  
Expression Of Genes ◽  
Genome Wide ◽  
Spindle Dynamics ◽  
Chromosome Alignment

AbstractKinesin-8 proteins are microtubule motors that are often involved in regulation of mitotic spindle length and chromosome alignment. They move towards the ends of spindle microtubules and regulate the dynamics of these ends due, at least in some species, to their microtubule depolymerization activity. Plasmodium spp. exhibit an atypical endomitotic cell division in which chromosome condensation and spindle dynamics are not well understood in the different proliferative stages. Genome-wide homology analysis of Plasmodium spp. revealed the presence of two Kinesin-8 motor proteins (Kinesin-8X and Kinesin-8B). Here we have studied the biochemical properties of Kinesin-8X and its role in parasite proliferation. In vitro, Kinesin-8X showed motile and depolymerization activities like other Kinesin-8 motors. To understand its role in cell division, we have used protein tagging and live cell imaging to define the location of Plasmodium Kinesin-8X during all proliferative stages of the P berghei life cycle. Furthermore, we have used gene targeting to analyse the function of Kinesin-8X. The results reveal a spatio-temporal involvement of Kinesin-8X in spindle dynamics and its association with both mitotic and meiotic spindles and the putative microtubule organising centre (MTOC). Deletion of the Kinesin-8X gene showed that this protein is required for endomitotic division during oocyst development and is therefore necessary for parasite replication within the mosquito gut, and for transmission to the vertebrate host. Consistently, transcriptome analysis of Δkinesin-8X parasites reveals modulated expression of genes involved mainly in microtubule-based processes, chromosome organisation and the regulation of gene expression supporting a role in cell division.Author SummaryKinesins are microtubule-based motors that play key roles in intracellular transport, cell division and motility. Members of the Kinesin-8 family contribute to chromosome alignment during cell division in many eukaryotes. However, the roles of kinesins in the atypical cell division in Plasmodium, the causative agent of malaria, is not known. In contrast to many other eukaryotes, Plasmodium proliferates by endomitosis, in which genome replication and division occur within a nucleus bounded by a persistent nuclear envelope. We show that the Plasmodium genome encodes only nine kinesins and we further investigate the role of Kinesin-8X throughout the Plasmodium life cycle using biochemical and gene targeting approaches. We show that Plasmodium Kinesin-8X has microtubule-based motility and depolymerization activity. We also show that Kinesin-8X is probably localized on putative MTOCs and spindles during cell division in most of the stages of P. berghei life cycle. By gene deletion we demonstrate that Kinesin-8X is essential for normal oocyst development and sporozoite formation. Genome-wide RNA analysis of Δkinesin-8X parasites reveals modulated expression of genes involved in microtubule-based processes. Overall, the data suggest that Kinesin-8X is a molecular motor that plays essential roles during endomitosis in oocyst development in the mosquito, contributing to parasite transmission.

scholarly journals Glassy dynamics in models of confluent tissue with mitosis and apoptosis

Soft Matter ◽  
2019 ◽  
Vol 15 (44) ◽  
pp. 9133-9149 ◽  
Author(s):  
Michael Czajkowski ◽  
Daniel M. Sussman ◽  
M. Cristina Marchetti ◽  
M. Lisa Manning
Keyword(s):  
Cell Death ◽  
Life Cycle ◽  
Cell Division ◽  
Epithelial Tissue ◽  
Vertex Model ◽  
Glassy Dynamics ◽  
Cell Life ◽  
Active Vertex

Using a new Active Vertex Model of confluent epithelial tissue, we investigate the effect of cell division and cell death on previously identified glassy dynamics and establish how fast the cell life cycle must be in order to disrupt the observed dynamical signatures of glass-like behavior.

Ultrastructural changes of the plasmalemma and the cell wall during the life cycle of Cyanidium caldarium

1968 ◽  
Vol 171 (1023) ◽  
pp. 249-259 ◽  
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Life Cycle ◽  
Cell Division ◽  
Surface Pattern ◽  
Ultrastructural Changes ◽  
Adjacent Cell ◽  
Cyanidium Caldarium ◽  
Stage Of Development ◽  
Dominant Feature

During the life cycle of the unicellular alga Cyanidium caldarium the surfaces of the plasmalemma and the adjacent cell wall develop a number of differentiated structures which can be demonstrated with the freeze-etching technique. While cell division takes place, the plasma membrane is undifferentiated and covered with randomly distributed 55 and 80 Å particles as well as small holes from torn out particles that can be found adhering to the adjacent cell wall. The 80 Å particles possess a substructure and sometimes 40 Å fibrils can be seen leading from these particles into the cell wall. Just after cell division, shallow depressions showing a hexagonal surface pattern with a spacing of 105 Å and arrays of approximately hexagonally packed 55 Å particles are formed on the plasmalemma. The corresponding structures found on the cell wall are particle-studded humps, which fit into the shallow depressions, and faintly striated regions, which match the 55 Å particle arrays. During the next stage of development, the hexagonally patterned shallow depressions on the plasma membrane are transformed into regularly striated 300 to 350 Å wide and approximately 250 Å deep folds, while the arrays of 55 Å particles increase in size. On the adjacent cell wall we can follow the development of the particle-studded humps into ridges covered with 70 Å particles. The plasmalemma of old mature cells is characterized by long striated folds that replace nearly all network structured depressions, and a few small arrays of 55 Å particles. Long ridges covered with particles are the corresponding dominant feature on the inside of the cell wall. Prior to cell division, the striated folds and the other differentiations of the plasmalemma are broken down and eventually disappear so that the cell has again an undifferentiated ‘embryonic’ plasma membrane for cell division. Simultaneously the differentiated structures on the cell wall disappear. All the described particles and units forming plasma membrane differentiations seem to be confined to the surface layer of the plasmalemma. The outlined development cycle of the plasmalemma of Cyanidium shows that biological membranes have the potential to differentiate in time and space.

scholarly journals Identification of a gene that shortens clonal life span of Paramecium tetraurelia.

Genetics ◽  
1989 ◽  
Vol 123 (4) ◽  
pp. 749-754 ◽  
Author(s):  
Y Takagi ◽  
K Izumi ◽  
H Kinoshita ◽  
T Yamada ◽  
K Kaji ◽  
...  
Keyword(s):  
Cell Division ◽  
Life Span ◽  
Recessive Mutation ◽  
Supporting Evidence ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Fission Rate ◽  
Cellular Life ◽  
Controlling Mechanism ◽  
Pleiotropic Gene

Abstract We have isolated a Paramecium tetraurelia mutant that divides slowly in daily reisolation cultures and repeats short clonal life spans after successive autogamies. Here we show, using breeding analysis, that a recessive mutation is responsible for the low fission rate and that this low rate is closely related to the short clonal life span. We conclude that a single pleiotropic gene controls these traits and have named it jumyo. In an attempt to further characterize the jumyo mutant, we have revealed that it has a culture life span similar to that of the wild-type cells and that, when mass cultured, it can divide as rapidly as wild-type cells. There was strong evidence that the mutant cells excreted into culture medium some substance that promotes their cell division. These findings may not only present supporting evidence for the hypothesis that the cellular life span is genetically programmed but also give a material basis for the study of the controlling mechanism of cell division in relation to the clonal life span.

scholarly journals Fussing about fission: defining variety among mainstream and exotic apicomplexan cell division modes

2020 ◽  
Author(s):  
Marc-Jan Gubbels ◽  
Caroline D. Keroack ◽  
Sriveny Dangoudoubiyam ◽  
Hanna L. Worliczek ◽  
Aditya S. Paul ◽  
...  
Keyword(s):  
Life Cycle ◽  
Cell Division ◽  
Opportunistic Infections ◽  
Historical Context ◽  
Binary Fission ◽  
Model Organisms ◽  
Babesia Bigemina ◽  
Offspring Number ◽  
Biological Studies ◽  
Unique Cell

AbstractCellular reproduction defines life, yet our textbook-level understanding of cell division is limited to a small number of model organisms centered around humans. The horizon on cell division variants is expanded here by advancing insights on the fascinating cell division modes found in the Apicomplexa, a key group of protozoan parasites. The Apicomplexa display remarkable variation in offspring number, whether karyokinesis follows each S/M-phase or not, and whether daughter cells bud in the cytoplasm or bud from the cortex. We find that the terminology used to describe the various manifestations of asexual apicomplexan cell division emphasizes either the number of offspring or site of budding, which are not directly comparable features and has led to confusion in the literature. Division modes have been primarily studied in two human pathogenic Apicomplexa, malaria-causing Plasmodium spp. and Toxoplasma gondii, a major cause of opportunistic infections. Plasmodium spp. divide asexually by schizogony, producing multiple daughters per division round through a cortical budding process, though at several life-cycle nuclear amplifications are not followed by karyokinesis. T. gondii divides by endodyogeny producing two internally budding daughters per division round. Here we add to this diversity in replication mechanisms by considering the cattle parasite Babesia bigemina and the pig parasite Cystoisospora suis. B. bigemina produces two daughters per division round by a ‘binary fission’ mechanism whereas C. suis produces daughters through both endodyogeny and multiple internal budding known as endopolygeny. In addition, we provide new data from the causative agent of equine protozoal myeloencephalitis (EPM), Sarcocystis neurona, which also undergoes endopolygeny but differs from C. suis by maintaining a single multiploid nucleus. Overall, we operationally define two principally different division modes: internal budding found in cyst-forming Coccidia (comprising endodyogeny and two forms of endopolygeny) and external budding found in the other parasites studied (comprising the two forms of schizogony, binary fission and multiple fission). Progressive insights into the principles defining the molecular and cellular requirements for internal versus external budding, as well as variations encountered in sexual stages are discussed. The evolutionary pressures and mechanisms underlying apicomplexan cell division diversification carries relevance across Eukaryota.Contribution to the FieldMechanisms of cell division vary dramatically across the Tree of Life, but the mechanistic basis has only been mapped for several model organisms. Here we present cell division strategies across Apicomplexa, a group of obligate intracellular parasites with significant impact on humans and domesticated animals. Asexual apicomplexan cell division is organized around assembly of daughter buds, but division forms differ in the cellular site of budding, number of offspring per division round, whether each S-phase follows karyokinesis and if mitotic rounds progress synchronously. This varies not just between parasites, but also between different life-cycle stages of a given species. We discuss the historical context of terminology describing division modes, which has led to confusion on how different modes relate to each other. Innovations in cell culture and genetics together with light microscopy advances have opened up cell biological studies that can shed light on this puzzle. We present new data for three division modes barely studied before. Together with existing data, we show how division modes are organized along phylogenetic lines and differentiate along external and internal budding mechanisms. We also discuss new insights into how the variations in division mode are regulated at the molecular level, and possess unique cell biological requirements.

scholarly journals Cellulosome Localization Patterns Vary across Life Stages of Anaerobic Fungi

mBio ◽  
2021 ◽  
Author(s):  
Stephen P. Lillington ◽  
William Chrisler ◽  
Charles H. Haitjema ◽  
Sean P. Gilmore ◽  
Chuck R. Smallwood ◽  
...  
Keyword(s):  
Life Cycle ◽  
Attractive Potential ◽  
Anaerobic Fungi ◽  
Life Stages ◽  
Waste Biomass ◽  
Knowledge Gaps ◽  
Plant Matter ◽  
Cellular Life

Anaerobic fungi ( Neocallimastigomycota ) isolated from the guts of herbivores excel at degrading ingested plant matter, making them attractive potential platform organisms for converting waste biomass into valuable products, such as chemicals and fuels. Major contributors to their biomass-hydrolyzing power are the multienzyme cellulosome complexes that anaerobic fungi produce, but knowledge gaps in how cellulosome production is controlled by the cellular life cycle and how cells spatially deploy cellulosomes complicate the use of anaerobic fungi and their cellulosomes in industrial bioprocesses.

scholarly journals Stable transfection in the protist Corallochytrium limacisporum allows identification of novel cellular features among unicellular relatives of animals

2020 ◽  
Author(s):  
Aleksandra Kożyczkowska ◽  
Sebastián R. Najle ◽  
Eduard Ocaña-Pallarès ◽  
Cristina Aresté ◽  
Iñaki Ruiz-Trillo ◽  
...  
Keyword(s):  
Life Cycle ◽  
Cell Division ◽  
Recent Work ◽  
Complex Life Cycle ◽  
Stable Transfection ◽  
Genetic Changes ◽  
Genetic Tools ◽  
Biological Features ◽  
Cellular Modifications ◽  
Cellular Components

ABSTRACTThe evolutionary path from protists to multicellular animals remains a mystery. Recent work on the genomes of several unicellular relatives of animals has shaped our understanding of the genetic changes that may have occurred in this transition. However, the specific cellular modifications that took place to accommodate these changes remain unclear. Functional approaches are now needed to unravel how different cell biological features evolved. Recent work has already established genetic tools in three of the four unicellular lineages closely related to animals (choanoflagellates, filastereans, and ichthyosporeans). However, there are no genetic tools available for Corallochytrea, the lineage that seems to have the widest mix of fungal and metazoan features, as well as a complex life cycle. Here, we describe the development of stable transfection in the corallochytrean Corallochytrium limacisporum. Using a battery of cassettes to tag key cellular components, such as nucleus, plasma membrane, cytoplasm and actin filaments, we employ live imaging to discern previously unknown biological features of C. limacisporum. In particular, we identify two different paths for cell division—binary fission and coenocytic growth—that reveal a non-linear life cycle in C. limacisporum. Additionally, we found that C. limacisporum is binucleate for most of its life cycle, and that, contrary to what happens in most eukaryotes, nuclear division is decoupled from cell division. The establishment of these tools in C. limacisporum fills an important gap in the unicellular relatives of animals, opening up new avenues of research with broad taxon sampling to elucidate the specific cellular changes that occurred in the evolution of animals.

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