scholarly journals Kinetochores and chromatin diminution in early embryos of Parascaris univalens.

1992 ◽  
Vol 118 (1) ◽  
pp. 23-32 ◽  
Author(s):  
C Goday ◽  
J M González-García ◽  
M R Esteban ◽  
G Giovinazzo ◽  
S Pimpinelli
Keyword(s):  
Mitotic Spindle ◽  
Cell Types ◽  
Entire Length ◽  
Mitotic Chromosomes ◽  
Chromatin Diminution ◽  
Kinetic Activity ◽  
Early Embryos ◽  
Spindle Microtubules ◽  
Egg Shell ◽  
Different Cell Types

In Parascaris the mitotic chromosomes of gonial germline cells are holocentric and possess a continuous kinetochore along their entire length. By contrast, in meiotic cells, the centromeric activity is restricted to the heterochromatic tips where direct insertion of spindle microtubules into chromatin without any kinetochore plate is seen. In the presomatic cells of early embryos, which undergo heterochromatin elimination, only euchromatin shows kinetic activity. After developing a technique to separate the very resistant egg shell from the embryos, we studied the cell divisions during early embryogenesis by immunochemical and EM approaches. The results reported here show that in presomatic cells microtubules bind only the euchromatin where a continuous kinetochore plate is present. We also report observations suggesting that the binding of the long kinetochores to the mitotic spindle initiates to a limited number of sites and extends along the entire length, during chromosome condensation. The existence of different centromere stages in different cell types, rends Parascaris chromosomes a very good model to study centromere organization.

scholarly journals Chromosomal attachments set length and microtubule number in the Saccharomyces cerevisiae mitotic spindle

2014 ◽  
Vol 25 (25) ◽  
pp. 4034-4048 ◽  
Author(s):  
Natalie J. Nannas ◽  
Eileen T. O’Toole ◽  
Mark Winey ◽  
Andrew W. Murray
Keyword(s):  
Electron Microscopy ◽  
Saccharomyces Cerevisiae ◽  
Simple Model ◽  
Mitotic Spindle ◽  
Cell Types ◽  
Yeast Saccharomyces Cerevisiae ◽  
Spindle Poles ◽  
Length Regulation ◽  
Spindle Microtubules ◽  
Different Cell Types

The length of the mitotic spindle varies among different cell types. A simple model for spindle length regulation requires balancing two forces: pulling, due to micro­tubules that attach to the chromosomes at their kinetochores, and pushing, due to interactions between microtubules that emanate from opposite spindle poles. In the budding yeast Saccharomyces cerevisiae, we show that spindle length scales with kinetochore number, increasing when kinetochores are inactivated and shortening on addition of synthetic or natural kinetochores, showing that kinetochore–microtubule interactions generate an inward force to balance forces that elongate the spindle. Electron microscopy shows that manipulating kinetochore number alters the number of spindle microtubules: adding extra kinetochores increases the number of spindle microtubules, suggesting kinetochore-based regulation of microtubule number.

Calcitonin effects on myoblasts: an ultrastructural study

1995 ◽  
Vol 53 ◽  
pp. 910-911
Author(s):  
R. González Santander ◽  
M.V. Toledo Lobo ◽  
F.J. Martínez Alonso ◽  
G. Martínez Cuadrado ◽  
M. González-Santander Martínez ◽  
...  
Keyword(s):  
Saline Solution ◽  
Cell Types ◽  
Giant Cells ◽  
Main Role ◽  
Sterile Saline ◽  
Trophoblastic Cells ◽  
Intracellular Ca ◽  
Egg Shell ◽  
Different Cell Types ◽  
Multinucleate Giant Cells

Several studies have provided detailed descriptions about the effects of calcitonin (CT) on different cell types such as osteoclasts, multinucleate giant cells and trophoblastic cells. CT main role is associated with the maintenance of peripheral Ca2+ homeostasis and it may also modulate free intracellular Ca2+. Myoblasts are particularly sensitive to changes in extra and intracellular Ca2+ concentration, so we have studied CT effects on myotome myoblasts differentiation.Chick embryos from 56-59 h. of incubation (Hamburger and Hamilton stages 16-17) were injected with 0,25 IU of CT dissolved in 125 ul of 0,9 % sterile saline solution (CALSYNAR-50, from Rorer Labs.- synthetic lyophilized salmon CT made by Armour Pharmaceutical Co., Kankakee, Illinois, USA). CT was injected into the ammniotic cavity through a window in the egg shell. Afterwards, the window was closed and the eggs returned into the incubator, until embryos had incubated for 103 h., to reach H.H. stage 24. Some embryos were only injected with saline solution (controls).

Microtubule motors associated with kinetochores in mitotic cells

1993 ◽  
Vol 51 ◽  
pp. 76-77
Author(s):  
Linda Wordeman
Keyword(s):  
Mitotic Spindle ◽  
Centromere Region ◽  
Mitotic Chromosomes ◽  
Directed Movement ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Microtubule Motors ◽  
Double Label ◽  
Spindle Microtubules ◽  
Kinetochore Region

Chromosomes in dividing tissue culture cells exhibit three types of movement along mitotic spindle microtubules: l)Fast minus-end directed movement (prometaphase), 2)Plus-end directed movement, and 3) Slow minus-end directed movement (anaphase) . In all cases these movements are mediated by the kinetochore region of the centromere of mitotic chromosomes. This region consists of three domains based on both immunocytochemistry and electron microscopy. The outermost or kinetochore domain is composed of the distal fibrous corona and trilamminar plate. The central and pairing domains are located in the chromatin beneath the kinetochore. Both plus- and minus-end directed microtubule motors have been localized to the kinetochore region of mitotic CHO chromosomes. I have used double-label immunocytochemistry to map the location of these motors within the centromere region at the level of the light microscope. Furthermore, I have cloned and expressed a number of novel kinesin-related motors, two of which (Clone 26 and Clone 14) are localized to kinetochores and kinetochore microtubules, respectively.

Centrosomes and mitotic spindle poles: a recent liaison?

2015 ◽  
Vol 43 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Pavithra L. Chavali ◽  
Isabel Peset ◽  
Fanni Gergely
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Potential Benefit ◽  
Cell Types ◽  
Daughter Cells ◽  
Spindle Poles ◽  
Pericentriolar Material ◽  
Mitotic Spindle Assembly ◽  
Spindle Microtubules ◽  
Ordered Assembly

Centrosomes comprise two cylindrical centrioles embedded in the pericentriolar material (PCM). The PCM is an ordered assembly of large scaffolding molecules, providing an interaction platform for proteins involved in signalling, trafficking and most importantly microtubule nucleation and organization. In mitotic cells, centrosomes are located at the spindle poles, sites where spindle microtubules converge. However, certain cell types and organisms lack centrosomes, yet contain focused spindle poles, highlighting that despite their juxtaposition in cells, centrosomes and mitotic spindle poles are distinct physical entities. In the present paper, we discuss the origin of centrosomes and summarize their contribution to mitotic spindle assembly and cell division. We then describe the key molecular players that mediate centrosome attachment to mitotic spindle poles and explore why co-segregation of centrosomes and spindle poles into daughter cells is of potential benefit to organisms.

scholarly journals Volumetric morphometry reveals mitotic spindle width as the best predictor of spindle scaling

2021 ◽  
Author(s):  
Tobias Kletter ◽  
Sebastian Reusch ◽  
Nils Dempewolf ◽  
Christian Tischer ◽  
Simone Reber
Keyword(s):  
Cell Volume ◽  
Mitotic Spindle ◽  
Imaging Techniques ◽  
Automated Analysis ◽  
Cell Types ◽  
Cellular Structures ◽  
Scaling Relations ◽  
Quantitative Understanding ◽  
Intracellular Organelles ◽  
Different Cell Types

The function of cellular structures at the mesoscale is dependent on their geometry and proportionality to cell size. The mitotic spindle is a good example why length and shape of intracellular organelles matter. Spindle length determines the distance over which chromosomes will segregate and spindle shape ensures bipolarity. While we still lack a systematic and quantitative understanding of subcellular morphometrics, new imaging techniques and volumetric data analysis promise novel insights into scaling relations across different species. Here, we introduce Spindle3D, an open-source plug-in that allows for the quantitative, unbiased, and automated analysis of 3D fluorescent data of spindles and chromatin. We systematically analyse different cell types, including somatic cells, stem cells and one-cell embryos across different phyla to derive volumetric relations of spindle, chromatin, and cell volume. Taken together, our data indicate that mitotic spindle width is a robust indicator of spindle volume, which correlates linearly with chromatin and cell volume both within single cell types and across metazoan phyla.

Correlative Video Light, Immunofluorescence, and Electron Microscopy of Chromosome Attachment to the Forming Vertebrate Spindle: Implications for Force Production During Mitosis

1990 ◽  
Vol 48 (3) ◽  
pp. 192-193
Author(s):  
Conly L. Rieder ◽  
Stephen P. Alexander ◽  
John Hayden ◽  
Samuel S. Bowser
Keyword(s):  
Mitotic Spindle ◽  
Force Production ◽  
Cell Types ◽  
Chromosome Movement ◽  
Nuclear Envelope Breakdown ◽  
Molecular Force ◽  
Keratin Filaments ◽  
Chromosome Attachment ◽  
Spindle Microtubules ◽  
Chromosome Motion

This abstract summarizes a number of recently published observations from this laboratory on the formation of the mitotic spindle (1-3), and on the dynamic behavior of spindle microtubules (4).Since chromosome movement during mitosis is, for the most part, directed towards a pole the emphasis of most mitosis research is to elucidate the molecular force-producing mechanism(s) behind this movement. Past studies reveal that poleward chromosome motion is dependent on the attachment of spindle microtubules (MTs) to the kinetochore of the chromosome. However, the origin of these MTs and their role in force production remain controversial. It is similarly unclear whether prometaphase and anaphase chromosomes are moved by the same, or a different, force-producing mechanism(s).The mitotic spindle of cultured newt (T. granulosa) pneumocytes forms in an optically clear region of cytoplasm defined by a cage of keratin filaments (1). As in other cell types possessing an astral spindle, chromosomes in newt pneumocytes that are positioned closer to one pole at nuclear envelope breakdown initially form a monopolar attachment to, and move towards, that pole.

Temporal and spatial control of gene expression in early embryos of farm animals

2007 ◽  
Vol 19 (1) ◽  
pp. 35 ◽  
Author(s):  
Tiziana A. L. Brevini ◽  
Fabiana Cillo ◽  
Stefania Antonini ◽  
Valentina Tosetti ◽  
Fulvio Gandolfi
Keyword(s):  
Gene Expression ◽  
Embryonic Development ◽  
Cell Types ◽  
Farm Animals ◽  
Gradual Transition ◽  
Messenger Rnas ◽  
Control Of Gene Expression ◽  
Domestic Species ◽  
Early Embryos ◽  
Different Cell Types

A gradual transition from oocyte-derived mRNA and proteins to full embryonic transcription characterises early embryonic development. Messenger RNAs and proteins of maternal origin are accumulated into the oocyte throughout its growth in the ovary. Upon fertilisation, several mechanisms are activated that control the appropriate use of such material and prepare for the synthesis of new products. The present review will describe some of the mechanisms active in early embryos of domestic species. Data will be presented on the control of gene expression by the 3′ untranslated regions and their interaction with specialised sequences at the 5′ cap end. The process of RNA sorting and localisation, initially described in different cell types and in oocytes of lower species, will also be discussed, particularly in relation to its possible role in regulating early pig development. Finally, specific genes involved in the activation of cattle embryonic transcription will be described. This brief overview will provide some suggestions on how these different mechanisms may be integrated and cooperate to ensure the correct initiation of embryonic development.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

Processing and Characterization of Recombinant von Willebrand Factor Expressed in Different Cell Types Using a Vaccinia Virus Vector

1992 ◽  
Vol 67 (01) ◽  
pp. 154-160 ◽  
Author(s):  
P Meulien ◽  
M Nishino ◽  
C Mazurier ◽  
K Dott ◽  
G Piétu ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Von Willebrand Factor ◽  
Human Fibroblasts ◽  
Active Form ◽  
Cell Types ◽  
Biologically Active ◽  
L Cells ◽  
Von Willebrand ◽  
Different Cell Types ◽  
Willebrand Factor

SummaryThe cloning of the cDNA encoding von Willebrand factor (vWF) has revealed that it is synthesized as a large precursor (pre-pro-vWF) molecule and it is now clear that the prosequence or vWAgll is responsible for the intracellular multimerization of vWF. We have cloned the complete vWF cDNA and expressed it using a recombinant vaccinia virus as vector. We have characterized the structure and function of the recombinant vWF (rvWF) secreted from five different cell types: baby hamster kidney (BHK), Chinese hamster ovary (CHO), human fibroblasts (143B), mouse fibroblasts (L) and primary embryonic chicken cells. Forty-eight hours after infection, the quantity of vWF antigen found in the cell supernatant varied from 3 to 12 U/dl depending on the cell type. By SDS-agarose gel electrophoresis, the percentage of high molecular weight forms of vWF varied from 39 to 49% relative to normal plasma for BHK, CHO, 143B and chicken cells but was less than 10% for L cells. In all cell types, the two anodic subbands of each multimer were missing. The two cathodic subbands were easily detected only in BHK and L cells. By SDS-PAGE of reduced samples, pro-vWF was present in similar quantity to the fully processed vWF subunit in L cells, present in moderate amounts in BHK and CHO and in very low amounts in 143B and chicken cells. rvWF from all cells bound to collagen and to platelets in the presence of ristocetin, the latter showing a high correlation between binding efficiency and degree of multimerization. rvWF from all cells was also shown to bind to purified FVIII and in this case binding appeared to be independent of the degree of multimerization. We conclude that whereas vWF is naturally synthesized only by endothelial cells and megakaryocytes, it can be expressed in a biologically active form from various other cell types.

Role of Transcriptional Read-Through in PRE Activity in Drosophila melanogaster

Acta Naturae ◽  
2016 ◽  
Vol 8 (2) ◽  
pp. 79-86 ◽  
Author(s):  
P. V. Elizar’ev ◽  
D. V. Lomaev ◽  
D. A. Chetverina ◽  
P. G. Georgiev ◽  
M. M. Erokhin
Keyword(s):  
Dna Sequences ◽  
Cell Types ◽  
Transcription Terminator ◽  
Response Elements ◽  
Polycomb Response Elements ◽  
The Individual ◽  
Multicellular Organisms ◽  
Different Cell Types ◽  
Main Factor

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesnt prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.

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