scholarly journals The 3D architecture and molecular foundations of de novo centriole assembly via bicentrioles

2020 ◽  
Author(s):  
Sónia Gomes Pereira ◽  
Ana Laura Sousa ◽  
Catarina Nabais ◽  
Tiago Paixão ◽  
Alexander. J. Holmes ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
De Novo ◽  
Cellular Functions ◽  
Spindle Poles ◽  
3D Architecture ◽  
Centriole Assembly ◽  
Work Supports ◽  
Wall Components

Abstract/SummaryCentrioles are structurally conserved organelles, composing both centrosomes and cilia. In animal cycling cells, centrioles often form through a highly characterized process termed canonical duplication. However, a large diversity of eukaryotes form centrioles de novo through uncharacterized pathways. This unexplored diversity is key to understanding centriole assembly mechanisms and how they evolved to assist specific cellular functions. Here, combining electron microscopy and tomography, we show that during spermatogenesis of the moss Physcomitrium patens, centrioles are born as a co-axially oriented centriole pair united by a cartwheel. We observe that microtubules emanate from those bicentrioles, which localize to the spindle poles during cell division. Thereafter, each bicentriole breaks apart, and the two resulting sister centrioles mature asymmetrically, elongating specific microtubule triplets and a naked cartwheel. Subsequently, two cilia are assembled which are capable of beating asynchronously. We further show that conserved cartwheel and centriole wall components, SAS6, BLD10 and POC1 are expressed during spermatogenesis and are required for this de novo biogenesis pathway. Our work supports a scenario where centriole biogenesis is more diverse than previously thought and that conserved molecular modules underlie diversification of this essential pathway.

scholarly journals The 3D architecture and molecular foundations of de novo centriole assembly via bicentrioles

2021 ◽  
Author(s):  
Sónia Gomes Pereira ◽  
Ana Laura Sousa ◽  
Catarina Nabais ◽  
Tiago Paixão ◽  
Alexander J. Holmes ◽  
...  
Keyword(s):  
De Novo ◽  
3D Architecture ◽  
Centriole Assembly

scholarly journals Microtubules assemble near most kinetochores during early prometaphase in human cells

2018 ◽  
Vol 217 (8) ◽  
pp. 2647-2659 ◽  
Author(s):  
Vitali Sikirzhytski ◽  
Fioranna Renda ◽  
Irina Tikhonenko ◽  
Valentin Magidson ◽  
Bruce F. McEwen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Spindle Assembly ◽  
Human Cells ◽  
Spindle Poles

For proper segregation during cell division, each chromosome must connect to the poles of the spindle via microtubule bundles termed kinetochore fibers (K-fibers). K-fibers form by two distinct mechanisms: (1) capture of astral microtubules nucleated at the centrosome by the chromosomes’ kinetochores or (2) attachment of kinetochores to noncentrosomal microtubules with subsequent transport of the minus ends of these microtubules toward the spindle poles. The relative contributions of these alternative mechanisms to normal spindle assembly remain unknown. In this study, we report that most kinetochores in human cells develop K-fibers via the second mechanism. Correlative light electron microscopy demonstrates that from the onset of spindle assembly, short randomly oriented noncentrosomal microtubules appear in the immediate vicinity of the kinetochores. Initially, these microtubules interact with the kinetochores laterally, but end-on attachments form rapidly in the first 3 min of prometaphase. Conversion from lateral to end-on interactions is impeded upon inhibition of the plus end–directed kinetochore-associated kinesin CenpE.

Morphology and morphogenesis of Strongylidium pseudocrassum Wang and Nie, 1935, with redefinition of Strongylidium Sterki, 1878  (Protista: Ciliophora: Stichotrichia)

Zootaxa ◽  
2007 ◽  
Vol 1559 (1) ◽  
pp. 31-57 ◽  
Author(s):  
THIAGO DA SILVA PAIVA ◽  
INÁCIO DOMINGOS DA SILVA-NETO
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Division ◽  
Rare Species ◽  
De Novo ◽  
Current Knowledge ◽  
Northern Region ◽  
First Time ◽  
Scanning Electron

A population of the rare species Strongylidium pseudocrassum Wang and Nie, 1935, was discovered from a lagoon in the northern region of Rio de Janeiro, Brazil, and its morphology was investigated through protargol-impregnation, scanning electron microscopy and in vivo observations. Morphogenetic events of cell division and physiological reorganization were described for the first time to this species. It was found that S. pseudocrassum has the ventral cirral rows organized in the same manner as Pseudouroleptus caudatus Hemberger, 1985. However two independent primordia VI, one for the proter and other for the opisthe, are generated intrakinetally from the rightmost ventral cirral row. In addition, dorsal kineties replicate entirely “de novo” and do not fragment. Based on the data obtained, the genus Strongylidium was redefined and the species currently assigned to it were classified into five groups according to current knowledge on their ciliature and the combination S. lentum (Biernacka, 1963) nov. comb. is proposed.

scholarly journals The 3D Architecture and Molecular Foundations of De Novo Centriole Assembly Via Bicentrioles

2021 ◽  
Author(s):  
Sónia Gomes Pereira ◽  
Ana Laura Sousa ◽  
Catarina Nabais ◽  
Tiago Paixão ◽  
Alexander J. Holmes ◽  
...  
Keyword(s):  
De Novo ◽  
3D Architecture ◽  
Centriole Assembly

Studies on the de novo formation of centrioles: aster formation in the activated eggs of sea urchin

1977 ◽  
Vol 24 (1) ◽  
pp. 203-216 ◽  
Author(s):  
T. Miki-Noumura
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Sea Urchin ◽  
De Novo ◽  
Sea Urchin Eggs ◽  
Hexylene Glycol ◽  
Mitotic Inhibitors ◽  
Glycol Solution

Aster formation was studied in sea-urchin eggs artificially activated by Loeb's double method. The number of asters found in an activated egg ranged from 15–40. Observation by electron microscopy revealed the presence of a centriole in a high percentage of isolated asters, strongly suggesting that these centrioles are formed de novo in the activated eggs. Using negatively stained specimens, which were isolated with 5% hexylene glycol solution containing buffer and EGTA, the whole aster could be examined by electron microscopy. A microtubular framework in the aster, extending radially from the astral centre was observed. The effect of mitotic inhibitors on aster formation was found to be similar to that on cell division.

Correlation Between Cellular Functions and Morphological Changes of Human Trophoblast in Vitro

1975 ◽  
Vol 33 ◽  
pp. 600-601
Author(s):  
John C. Garancis ◽  
Robert O. Hussa ◽  
Michael T. Story ◽  
Donald Yorde ◽  
Roland A. Pattillo
Keyword(s):  
Electron Microscopy ◽  
Cellular Proliferation ◽  
Morphological Changes ◽  
Culture Fluid ◽  
Cellular Functions ◽  
Human Trophoblast ◽  
Transmission Electron ◽  
Marked Activity ◽  
Malignant Trophoblast

Human malignant trophoblast cells in continuous culture were incubated for 3 days in medium containing 1 mM N6-O2'-dibutyryl cyclic adenosine 3':5'-monophosphate (dibutyryl cyclic AMP) and 1 mM theophylline. The culture fluid was replenished daily. Stimulated cultures secreted many times more chorionic gonadotropin and estrogens than did control cultures in the absence of increased cellular proliferation. Scanning electron microscopy revealed remarkable surface changes of stimulated cells. Control cells (not stimulated) were smooth or provided with varying numbers of microvilli (Fig. 1). The latter, usually, were short and thin. The surface features of stimulated cells were considerably different. There was marked increase of microvilli which appeared elongated and thick. Many cells were covered with confluent polypoid projections (Fig. 2). Transmission electron microscopy demonstrated marked activity of cytoplasmic organelles. Mitochondria were increased in number and size; some giant forms with numerous cristae were observed.

Study of Phosphocalcic Glasses from SiO2-CaO-P2O5 System with and Without Silver II. The bioactivity analysis by FTIR, SEM methods and microbiological study of silver-doped glasses

2017 ◽  
Vol 68 (6) ◽  
pp. 1188-1192
Author(s):  
Daniela Avram ◽  
Nicolae Angelescu ◽  
Dan Nicolae Ungureanu ◽  
Ionica Ionita ◽  
Iulian Bancuta ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Body Fluid ◽  
Pathogenic Bacteria ◽  
De Novo ◽  
Microbiological Examination ◽  
Doped Glasses ◽  
P2o5 System ◽  
Scanning Electron

The study in vitro of the glass powders bioactivity was performed by soaking them in simulated body fluid for 3 to 21 days at a temperature of 37�C and pH = 7.20. The synthesis de novo of hydroxyapatite, post soaking was confirmed by Fourier Transform Infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The study of the antimicrobial activity was performed by microbiological examination on two strains of pathogenic bacteria involved in postoperative nosocomial infections.

Rapid centriole assembly inNaegleriareveals conserved roles for both de novo and mentored assembly

Cytoskeleton ◽  
2016 ◽  
Vol 73 (3) ◽  
pp. 109-116 ◽  
Author(s):  
Lillian K. Fritz-Laylin ◽  
Yaron Y. Levy ◽  
Edward Levitan ◽  
Sean Chen ◽  
W. Zacheus Cande ◽  
...  
Keyword(s):  
De Novo ◽  
Centriole Assembly

Asymmetric cell division in fucoid algae: a role for cortical adhesions in alignment of the mitotic apparatus

2001 ◽  
Vol 114 (23) ◽  
pp. 4319-4328
Author(s):  
Sherryl R. Bisgrove ◽  
Darryl L. Kropf
Keyword(s):  
Cell Division ◽  
Asymmetric Cell Division ◽  
Cell Cortex ◽  
Mitotic Apparatus ◽  
Pharmacological Agents ◽  
Division Plane ◽  
Adhesion Sites ◽  
Spindle Poles ◽  
Pelvetia Compressa ◽  
Two Phases

The first cell division in zygotes of the fucoid brown alga Pelvetia compressa is asymmetric and we are interested in the mechanism controlling the alignment of this division. Since the division plane bisects the mitotic apparatus, we investigated the timing and mechanism of spindle alignments. Centrosomes, which give rise to spindle poles, aligned with the growth axis in two phases – a premetaphase rotation of the nucleus and centrosomes followed by a postmetaphase alignment that coincided with the separation of the mitotic spindle poles during anaphase and telophase. The roles of the cytoskeleton and cell cortex in the two phases of alignment were analyzed by treatment with pharmacological agents. Treatments that disrupted cytoskeleton or perturbed cortical adhesions inhibited pre-metaphase alignment and we propose that this rotational alignment is effected by microtubules anchored at cortical adhesion sites. Postmetaphase alignment was not affected by any of the treatments tested, and may be dependent on asymmetric cell morphology.

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