The perinuclear microtubule-organizing center and the synaptonemal complex of higher plants share a common antigen: its putative transfer and role in meiotic chromosomal ordering

Chromosoma ◽  
1996 ◽  
Vol 104 (6) ◽  
pp. 405-413 ◽  
Author(s):  
Anne-Catherine Schmit ◽  
Marie-Christine Endl� ◽  
Anne-Marie Lambert
Keyword(s):  
Synaptonemal Complex ◽  
Higher Plants ◽  
Common Antigen ◽  
Microtubule Organizing Center ◽  
Organizing Center

scholarly journals The role of the ameiotic1 gene in the initiation of meiosis and in subsequent meiotic events in maize.

Genetics ◽  
1993 ◽  
Vol 135 (4) ◽  
pp. 1151-1166 ◽  
Author(s):  
I Golubovskaya ◽  
Z K Grebennikova ◽  
N A Avalkina ◽  
W F Sheridan
Keyword(s):  
Meiotic Division ◽  
Higher Plants ◽  
Gene Interaction ◽  
Microtubule Organizing Center ◽  
Spindle Fiber ◽  
Chromosome Synapsis ◽  
Organizing Center ◽  
Relationship Of ◽  
The Relationship

Abstract Understanding the initiation of meiosis and the relationship of this event with other key cytogenetic processes are major goals in studying the genetic control of meiosis in higher plants. Our genetic and structural analysis of two mutant alleles of the ameiotic1 gene (am1 and am1-praI) suggest that this locus plays an essential role in the initiation of meiosis in maize. The product of the ameiotic1 gene affects an earlier stage in the meiotic sequence than any other known gene in maize and is important for the irreversible commitment of cells to meiosis and for crucial events marking the passage from premeiotic interphase into prophase I including chromosome synapsis. It appears that the period of ameiotic1 gene function in meiosis at a minimum covers the interval from some point during premeiotic interphase until the early zygotene stage of meiosis. To study the interaction of genes in the progression of meiosis, several double meiotic mutants were constructed. In these double mutants (i) the ameiotic1 mutant allele was brought together with the meiotic mutation (afd1) responsible for the fixation of centromeres in meiosis; and with the mutant alleles of the three meiotic genes that control homologous chromosome segregation (dv1, ms43 and ms28), which impair microtubule organizing center organization, the orientation of the spindle fiber apparatus, and the depolymerization of spindle filaments after the first meiotic division, respectively; (ii) the afd1 mutation was combined with two mutations (dsy1 and as1) affecting homologous pairing; (iii) the ms43 mutation was combined with the as1, the ms28 and the dv1 mutations; and (iv) the ms28 mutation was combined with the dv1 mutation and the ms4 (polymitotic1) mutations. An analysis of gene interaction in the double mutants led us to conclude that the ameiotic1 gene is epistatic over the afd1, the dv1, the ms43 and the ms28 genes but the significance of this relationship requires further analysis. The afd gene appears to function from premeiotic interphase throughout the first meiotic division, but it is likely that its function begins after the start of the ameiotic1 gene expression. The afd1 gene is epistatic over the two synaptic mutations dsy1 and as1 and also over the dv1 mutation. The new ameiotic*-485 and leptotene arrest*-487 mutations isolated from an active Robertson's Mutator stocks take part in the control of the initiation of meiosis.

scholarly journals Microtubule nucleating sites in higher plant cells identified by an auto-antibody against pericentriolar material.

1985 ◽  
Vol 101 (1) ◽  
pp. 319-324 ◽  
Author(s):  
L Clayton ◽  
C M Black ◽  
C W Lloyd
Keyword(s):  
Higher Plants ◽  
Plant Cells ◽  
Nuclear Surface ◽  
Microtubule Organizing Center ◽  
Higher Plant ◽  
Spindle Poles ◽  
Late Anaphase ◽  
Organizing Center ◽  
Pericentriolar Material ◽  
Auto Antibody

Human scleroderma serum 5051, which is known to recognize the amorphous pericentriolar microtubule organizing center material of a variety of vertebrate cells, was found to immunostain spindle poles of meristematic higher plants from pre-prophase to late anaphase. Subsequently, during cytokinesis, staining was redistributed around the reforming telophase nuclei, but was not evident in the cytokinetic phragmoplast. At the transition between telophase and interphase, before the typical cortical interphase microtubule array was established, short microtubules radiated from the nucleus and in such cells the material recognized by 5051 was located around the daughter nuclei and not the cortex. These observations have led us to propose that the perinuclear region, or the nuclear surface, may function as a nucleation center for both spindle and interphase microtubules in higher plant cells.

Three-Dimensional reconstruction of isolated centrosomes by automated electron tomography

1994 ◽  
Vol 52 ◽  
pp. 310-311
Author(s):  
M.B. Braunfeld ◽  
M. Moritz ◽  
B.M. Alberts ◽  
J.W. Sedat ◽  
D.A. Agard
Keyword(s):  
Electron Tomography ◽  
Three Dimensional ◽  
Vital Role ◽  
Complex Nature ◽  
Animal Cells ◽  
Microtubule Organizing Center ◽  
Nucleation Sites ◽  
Dimensional Reconstruction ◽  
Organizing Center ◽  
Resolution Model

In animal cells, the centrosome functions as the primary microtubule organizing center (MTOC). As such the centrosome plays a vital role in determining a cell's shape, migration, and perhaps most importantly, its division. Despite the obvious importance of this organelle little is known about centrosomal regulation, duplication, or how it nucleates microtubules. Furthermore, no high resolution model for centrosomal structure exists.We have used automated electron tomography, and reconstruction techniques in an attempt to better understand the complex nature of the centrosome. Additionally we hope to identify nucleation sites for microtubule growth.Centrosomes were isolated from early Drosophila embryos. Briefly, after large organelles and debris from homogenized embryos were pelleted, the resulting supernatant was separated on a sucrose velocity gradient. Fractions were collected and assayed for centrosome-mediated microtubule -nucleating activity by incubating with fluorescently-labeled tubulin subunits. The resulting microtubule asters were then spun onto coverslips and viewed by fluorescence microscopy.

Genetic interactions between CDC31 and KAR1, two genes required for duplication of the microtubule organizing center in Saccharomyces cerevisiae.

Genetics ◽  
1994 ◽  
Vol 137 (2) ◽  
pp. 407-422 ◽  
Author(s):  
E A Vallen ◽  
W Ho ◽  
M Winey ◽  
M D Rose
Keyword(s):  
Copy Number ◽  
Gene Dosage ◽  
Spindle Pole Body ◽  
Direct Interaction ◽  
Spindle Pole ◽  
High Copy Number ◽  
Temperature Sensitive ◽  
Microtubule Organizing Center ◽  
Recessive Mutations ◽  
Organizing Center

Abstract KAR1 encodes an essential component of the yeast spindle pole body (SPB) that is required for karyogamy and SPB duplication. A temperature-sensitive mutation, kar1-delta 17, mapped to a region required for SPB duplication and for localization to the SPB. To identify interacting SPB proteins, we isolated 13 dominant mutations and 3 high copy number plasmids that suppressed the temperature sensitivity of kar1-delta 17. Eleven extragenic suppressor mutations mapped to two linkage groups, DSK1 and DSK2. The extragenic suppressors were specific for SPB duplication and did not suppress karyogamy-defective alleles. The major class, DSK1, consisted of mutations in CDC31. CDC31 is required for SPB duplication and encodes a calmodulin-like protein that is most closely related to caltractin/centrin, a protein associated with the Chlamydomonas basal body. The high copy number suppressor plasmids contained the wild-type CDC31 gene. One CDC31 suppressor allele conferred a temperature-sensitive defect in SPB duplication, which was counter-suppressed by recessive mutations in KAR1. In spite of the evidence for a direct interaction, the strongest CDC31 alleles, as well as both DSK2 alleles, suppressed a complete deletion of KAR1. However, the CDC31 alleles also made the cell supersensitive to KAR1 gene dosage, arguing against a simple bypass mechanism of suppression. We propose a model in which Kar1p helps localize Cdc31p to the SPB and that Cdc31p then initiates SPB duplication via interaction with a downstream effector.

scholarly journals Evidence for rapid structural and functional changes of the melanophore microtubule-organizing center upon pigment movements

1979 ◽  
Vol 83 (3) ◽  
pp. 623-632 ◽  
Author(s):  
M Schliwa ◽  
U Euteneuer ◽  
W Herzog ◽  
K Weber
Keyword(s):  
Complete Removal ◽  
Cell System ◽  
The State ◽  
Microtubule Assembly ◽  
Microtubule Organizing Center ◽  
Functional Changes ◽  
Organizing Center ◽  
Pigment Distribution ◽  
And Function ◽  
In Cells

Melanophores of the angelfish, pterophyllum scalare, have previously been shown to display approximately 2,400 microtubules in cells wih pigment dispersed; these microtubules radiate from a presumptive organizing center, the central apparatus (CA), and their number is reduced to approximately 1,000 in the state with aggregated pigment (M. Schliwa and U. Euteneuer, 1978, J. Supramol. Struct. 8:177-190). In an attempt to elucidate the factors controlling this rapid reorganization of the microtubule apparatus, structure and function of the CA have been investigated under different physiological conditions. As a function of the state of pigment distribution, melanophores differ markedly with respect to CA organization. A complex of dense amorphous aggregates and associated fuzzy material, several micrometers in diameter, surrounds the centrioles in cells with pigment dispersed, and numerous microtubules emanate from this complex in a radial fashion. In the aggregated state, on the other hand, few microtubules are observed in the pericentiolar region, and the amount of fibrous material is greatly reduced. These changes in CA morphology as a function of the state of pigment distribution are associated with a marked difference in its capacity to initiatiate the assembly of microtubules from exogenous pure porcine brain tubulin in lysed cell preparations. After complete removal of preexisting microtubules, cells lysed in the dispersed state into a solution of 1-2 mg/ml pure tubulin have numerous microtubules associated with the CA in radial fashion, while cells lysed in the aggregated state nucleate the assembly of only a few microtubules. We conclude that it is the activity of the CA that basically regulates the expression of microtubules. This regulation is achieved through a variation in the capacity to initiate microtubule assembly. Increase or decrease in the amount of dense material, as readily observed in the cell system studied here, seems to be a morphologic expression of such a physiologic function.

scholarly journals Murine Cytomegalovirus Capsid Assembly Is Dependent on US22 Family Gene M140 in Infected Macrophages

2009 ◽  
Vol 83 (15) ◽  
pp. 7449-7456 ◽  
Author(s):  
Laura K. Hanson ◽  
Jacquelyn S. Slater ◽  
Victoria J. Cavanaugh ◽  
William W. Newcomb ◽  
Lisa L. Bolin ◽  
...  
Keyword(s):  
Dna Cleavage ◽  
Early Gene ◽  
Murine Cytomegalovirus ◽  
Genome Replication ◽  
Microtubule Organizing Center ◽  
Viral Dna ◽  
Dnase Treatment ◽  
Organizing Center ◽  
Significant Impairment ◽  
The Stability

ABSTRACT Macrophages are an important target cell for infection with cytomegalovirus (CMV). A number of viral genes that either are expressed specifically in this cell type or function to optimize CMV replication in this host cell have now been identified. Among these is the murine CMV (MCMV) US22 gene family member M140, a nonessential early gene whose deletion (RVΔ140) leads to significant impairment in virus replication in differentiated macrophages. We have now determined that the defect in replication is at the stage of viral DNA encapsidation. Although the rate of RVΔ140 genome replication and extent of DNA cleavage were comparable to those for revertant virus, deletion of M140 resulted in a significant reduction in the number of viral capsids in the nucleus, and the viral DNA remained sensitive to DNase treatment. These data are indicative of incomplete virion assembly. Steady-state levels of both the major capsid protein (M86) and tegument protein M25 were reduced in the absence of the M140 protein (pM140). This effect may be related to the localization of pM140 to an aggresome-like, microtubule organizing center-associated structure that is known to target misfolded and overexpressed proteins for degradation. It appears, therefore, that pM140 indirectly influences MCMV capsid formation in differentiated macrophages by regulating the stability of viral structural proteins.

Peroxynitrite Deteriorates Oocyte Quality through Disassembly of Microtubule Organizing Center

2015 ◽  
Vol 87 ◽  
pp. S114
Author(s):  
Sana Khan ◽  
Faten Shaeib ◽  
Mili Thakur ◽  
Roohi Jeelani ◽  
Husam M Abu-Soud
Keyword(s):  
Oocyte Quality ◽  
Microtubule Organizing Center ◽  
Organizing Center
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