A Self-Associating Protein Critical for Chromosome Attachment, Division, and Polar Organization in Caulobacter

Abstract Males carrying different X chromosomes were tested for the ability to produce daughters with attached-X chromosomes. This ability is characteristic of males carrying an X chromosome derived from 59b-z, a multiply marked X chromosome, and is especially pronounced in males carrying the unstable 59b-z chromosomes Uc and Uc-lr. Recombination experiments with one of the Uc-lr chromosomes showed that the formation of compound chromosomes depends on two widely separated segments. One of these is proximal to the forked locus and is probably proximal to the carnation locus. This segment may contain the actual site of chromosome attachment. The other essential segment lies between the crossveinless and vermilion loci and may contain multiple factors that influence the attachment process.

Download Full-text

Janus-Type Dendromesogens: A Tool to Control the Nanosegregation and Polar Organization of Bent-Core Structures

Chemistry of Materials ◽

10.1021/cm302144f ◽

2013 ◽

Vol 25 (3) ◽

pp. 286-296 ◽

Cited By ~ 19

Author(s):

Nélida Gimeno ◽

Jorge Vergara ◽

Miguel Cano ◽

José Luis Serrano ◽

M. Blanca Ros ◽

...

Keyword(s):

Polar Organization

Download Full-text

The EBNA1 Protein of Epstein-Barr Virus Functionally Interacts with Brd4

Journal of Virology ◽

10.1128/jvi.01680-08 ◽

2008 ◽

Vol 82 (24) ◽

pp. 12009-12019 ◽

Cited By ~ 68

Author(s):

Ammy Lin ◽

Shan Wang ◽

Tin Nguyen ◽

Kathy Shire ◽

Lori Frappier

Keyword(s):

Transcriptional Activation ◽

Epstein Barr Virus ◽

Mitotic Chromosome ◽

Human Cells ◽

Host Proteins ◽

Enhancer Element ◽

Barr Virus ◽

Chromosome Attachment ◽

Infected Cells ◽

Epstein Barr

ABSTRACT The EBNA1 protein of Epstein-Barr virus (EBV) is essential for EBV latent infection in ensuring the replication and stable segregation of the EBV genomes and in activating the transcription of other EBV latency genes. We have tested the ability of four host proteins (Brd2, Brd4, DEK, and MeCP2) implicated in the segregation of papillomavirus and Kaposi's sarcoma-associated herpesvirus to support EBNA1-mediated segregation of EBV-based plasmids in Saccharomyces cerevisiae. We found that Brd4 enabled EBNA1-mediated segregation while Brd2 and MeCP2 had a general stimulatory effect on plasmid maintenance. EBNA1 interacted with Brd4 in both yeast and human cells through N-terminal sequences previously shown to mediate transcriptional activation but not segregation. In keeping with this interaction site, silencing of Brd4 in human cells decreased transcriptional activation by EBNA1 but not the mitotic chromosome attachment of EBNA1 that is required for segregation. In addition, Brd4 was found to be preferentially localized to the FR enhancer element regulated by EBNA1, over other EBV sequences, in latently EBV-infected cells. The results indicate that EBNA1 can functionally interact with Brd4 in native and heterologous systems and that this interaction facilitates transcriptional activation by EBNA1 from the FR element.

Download Full-text

The Instituto Antarctico Argentino

ARCTIC ◽

10.14430/arctic3524 ◽

1963 ◽

Vol 16 (2) ◽

pp. 82 ◽

Cited By ~ 1

Author(s):

Leonard A. LeSchack

Keyword(s):

Scientific Work ◽

Easy Access ◽

Administrative Staff ◽

Scientific Investigations ◽

International Geophysical Year ◽

Active Interest ◽

Polar Organization ◽

Work Done ◽

The Antarctic ◽

International Geophysical

... In view of the number of organizations annually participating in these expeditions, the Argentine Government decided to establish one central organization to be responsible for the scientific work done by Argentina in the Antarctic. In addition, this organization was to be the common repository for information gathered on previous Argentine expeditions, as well as for that of future endeavours. The Instituto Antartico Argentino was therefore established in Buenos Aires. It is a scientific and technical organization whose mission is to study the nature of the antarctic region. From its inception, it has steadily grown to occupy a prominent position in antarctic affairs and become the leading organization influential in all Argentine antarctic problems. By Presidential Order the organization entitled "Instituto Antartico Argentino 'Coronel Hernan Pujato' " was established on 17 April 1951 under the administration of the Minister of Technical Affairs. The name honored Coronel Hernan Pujato, who commanded the first Argentine Army antarctic expedition. He became the Institute's first Director. With the preparations for the International Geophysical Year underway, the Institute's activities expanded and Captain Rodolfo N. Panzarini, now a retired rear admiral, was named Director. He still retains this position and is the main driving force behind the organization (see Fig. 1). At the time of his nomination, the organization officially took the name "Instituto Antartico Argentino" (I.A.A.). The Institute is an in-house polar organization, containing in one building the entire administrative staff, scientists, technicians, laboratories, shops, and equipment storage facilities necessary to carry out scientific investigations in the Antarctic. There is an advantage in keeping under one roof the majority of persons with an active interest in antarctic work so that they can confer easily with one another, exchange data, and have easy access to a polar library. Such a closely knit organization constitutes a potentially powerful voice in antarctic affairs. This voice perhaps is not as great a consideration in the present thinking of other polar organizations as it is with the Argentines, whose interest in Antarctica, and in particular the Palmer Peninsula area, is very strong. ...

Download Full-text

Kinetochores are transported poleward along a single astral microtubule during chromosome attachment to the spindle in newt lung cells.

The Journal of Cell Biology ◽

10.1083/jcb.110.1.81 ◽

1990 ◽

Vol 110 (1) ◽

pp. 81-95 ◽

Cited By ~ 291

Author(s):

C L Rieder ◽

S P Alexander

Keyword(s):

Spatial Separation ◽

Time Lapse ◽

Spindle Pole ◽

Variable Number ◽

Fiber Formation ◽

Polar Regions ◽

Microtubule Depolymerization ◽

Chromosome Attachment ◽

Kinetochore Region ◽

Tubulin Immunofluorescence

During mitosis in cultured newt pneumocytes, one or more chromosomes may become positioned well removed (greater than 50 microns) from the polar regions during early prometaphase. As a result, these chromosomes are delayed for up to 5 h in forming an attachment to the spindle. The spatial separation of these chromosomes from the polar microtubule-nucleating centers provides a unique opportunity to study the initial stages of kinetochore fiber formation in living cells. Time-lapse Nomarski-differential interference contrast videomicroscopic observations reveal that late-attaching chromosomes always move, upon attachment, into a single polar region (usually the one closest to the chromosome). During this attachment, the kinetochore region of the chromosome undergoes a variable number of transient poleward tugs that are followed, shortly thereafter, by rapid movement of the chromosome towards the pole. Anti-tubulin immunofluorescence and serial section EM reveal that the kinetochores and kinetochore regions of nonattached chromosomes lack associated microtubules. By contrast, these methods reveal that the attachment and subsequent poleward movement of a chromosome correlates with the association of a single long microtubule with one of the kinetochores of the chromosome. This microtubule traverses the entire distance between the spindle pole and the kinetochore and often extends well past the kinetochore. From these results, we conclude that the initial attachment of a chromosome to the newt pneumocyte spindle results from an interaction between a single polar-nucleated microtubule and one of the kinetochores on the chromosome. Once this association is established, the kinetochore is rapidly transported poleward along the surface of the microtubule by a mechanism that is not dependent on microtubule depolymerization. Our results further demonstrate that the motors for prometaphase chromosome movement must be either on the surface of the kinetochore (i.e., within the corona but not the plate), distributed along the surface of the kinetochore microtubules, or both.

Download Full-text

Comparative analysis of DNA sequences of regions of X-chromosome attachment to the nuclear envelope of nurse cells Anopheles messeae Fall.

Russian Journal of Genetics ◽

10.1134/s1022795415060022 ◽

2015 ◽

Vol 51 (7) ◽

pp. 702-706

Author(s):

G. N. Artemov ◽

O. Yu. Vasil’eva ◽

V. N. Stegniy

Keyword(s):

Comparative Analysis ◽

Nuclear Envelope ◽

X Chromosome ◽

Dna Sequences ◽

Nurse Cells ◽

Chromosome Attachment

Download Full-text

Evidence that the spindle assembly checkpoint does not regulate APCFzy activity in Drosophila female meiosis

Genome ◽

10.1139/g11-079 ◽

2012 ◽

Vol 55 (1) ◽

pp. 63-67 ◽

Cited By ~ 6

Author(s):

Osamah Batiha ◽

Andrew Swan

Keyword(s):

Chromosome Segregation ◽

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Cyclin B ◽

Meiotic Spindle ◽

Loss Of Function ◽

Female Meiosis ◽

Chromosome Attachment ◽

Spindle Microtubules ◽

Made In

The spindle assembly checkpoint (SAC) plays an important role in mitotic cells to sense improper chromosome attachment to spindle microtubules and to inhibit APCFzy-dependent destruction of cyclin B and Securin; consequent initiation of anaphase until correct attachments are made. In Drosophila , SAC genes have been found to play a role in ensuring proper chromosome segregation in meiosis, possibly reflecting a similar role for the SAC in APCFzy inhibition during meiosis. We found that loss of function mutations in SAC genes, Mad2, zwilch, and mps1, do not lead to the predicted rise in APCFzy-dependent degradation of cyclin B either globally throughout the egg or locally on the meiotic spindle. Further, the SAC is not responsible for the inability of APCFzy to target cyclin B and promote anaphase in metaphase II arrested eggs from cort mutant females. Our findings support the argument that SAC proteins play checkpoint independent roles in Drosophila female meiosis and that other mechanisms must function to control APC activity.

Download Full-text

Micropatterned Macrophage Analysis Reveals Global Cytoskeleton Constraints Induced by Bacillus anthracis Edema Toxin

Infection and Immunity ◽

10.1128/iai.00479-15 ◽

2015 ◽

Vol 83 (8) ◽

pp. 3114-3125 ◽

Cited By ~ 10

Author(s):

Yannick Trescos ◽

Emilie Tessier ◽

Clémence Rougeaux ◽

Pierre L. Goossens ◽

Jean-Nicolas Tournier

Keyword(s):

Bacillus Anthracis ◽

Immune Cells ◽

Adherens Junction ◽

Peritoneal Macrophages ◽

Cell Physiology ◽

Actin Reorganization ◽

Content Type ◽

Cellular Physiology ◽

Edema Toxin ◽

Polar Organization

Bacillus anthracissecretes the edema toxin (ET) that disrupts the cellular physiology of endothelial and immune cells, ultimately affecting the adherens junction integrity of blood vessels that in turn leads to edema. The effects of ET on the cytoskeleton, which is critical in cell physiology, have not been described thus far on macrophages. In this study, we have developed different adhesive micropatterned surfaces (L and crossbow) to control the shape of bone marrow-derived macrophages (BMDMs) and primary peritoneal macrophages. We found that macrophage F-actin cytoskeleton adopts a specific polar organization slightly different from classical human HeLa cells on the micropatterns. Moreover, ET induced a major quantitative reorganization of F-actin within 16 h with a collapse at the nonadhesive side of BMDMs along the nucleus. There was an increase in size and deformation into a kidney-like shape, followed by a decrease in size that correlates with a global cellular collapse. The collapse of F-actin was correlated with a release of focal adhesion on the patterns and decreased cell size. Finally, the cell nucleus was affected by actin reorganization. By using this technology, we could describe many previously unknown macrophage cellular dysfunctions induced by ET. This novel tool could be used to analyze more broadly the effects of toxins and other virulence factors that target the cytoskeleton.

Download Full-text

Kinetochores capture astral microtubules during chromosome attachment to the mitotic spindle: direct visualization in live newt lung cells.

The Journal of Cell Biology ◽

10.1083/jcb.111.3.1039 ◽

1990 ◽

Vol 111 (3) ◽

pp. 1039-1045 ◽

Cited By ~ 171

Author(s):

J H Hayden ◽

S S Bowser ◽

C L Rieder

Keyword(s):

Light Microscopy ◽

Mitotic Spindle ◽

Dynamic Instability ◽

Lung Cells ◽

Polar Regions ◽

Clear Area ◽

Chromosome Attachment ◽

Initial Interaction ◽

Favorable Conditions ◽

First Time

When viewed by light microscopy the mitotic spindle in newt pneumocytes assembles in an optically clear area of cytoplasm, virtually devoid of mitochondria and other organelles, which can be much larger than the forming spindle. This unique optical property has allowed us to examine the behavior of individual microtubules, at the periphery of asters in highly flattened living prometaphase cells, by video-enhanced differential interference-contrast light microscopy and digital image processing. As in interphase newt pneumocytes (Cassimeris, L., N. K. Pryer, and E. D. Salmon. 1988. J. Cell Biol. 107:2223-2231), centrosomal (i.e., astral) microtubules in prometaphase cells appear to exhibit dynamic instability, elongating at a mean rate of 14.3 +/- 5.1 microns/min (N = 19) and shortening at approximately 16 microns/min. Under favorable conditions the initial interaction between a kinetochore and the forming spindle can be directly observed. During this process the unattached chromosome is repeatedly probed by microtubules projecting from one of the polar regions. When one of these microtubules contacts the primary constriction the chromosome rapidly undergoes poleward translocation. Our observations on living mitotic cells directly demonstrate, for the first time, that chromosome attachment results from an interaction between astral microtubules and the kinetochore.

Download Full-text