scholarly journals Reorganization and polarization of the meiotic bouquet-stage cell can be uncoupled from telomere clustering

2002 ◽  
Vol 115 (19) ◽  
pp. 3757-3766 ◽  
Author(s):  
C. R. Cowan
Keyword(s):  
Bouquet Stage

THE EFFECT OF COLCHICINE ON CHROMOSOME PAIRING

1977 ◽  
Vol 19 (2) ◽  
pp. 231-249 ◽  
Author(s):  
J. B. Thomas ◽  
P. J. Kaltsikes
Keyword(s):  
Aqueous Solution ◽  
Chromosome Pairing ◽  
Close Association ◽  
Tetraploid Wheat ◽  
Continuous Illumination ◽  
Hexaploid Triticale ◽  
Homologous Chromosomes ◽  
Wheat Hybrids ◽  
Bouquet Stage

Beginning at 120 hours prior to first metaphase of meiosis (MI) a 0.03% aqueous solution of colchicine was injected into the boot of pentaploid (hexaploid triticale × tetraploid wheat) hybrids developing at 20 °C ± 1° under continuous illumination. Colchicine applied 40 h or less prior to MI had no effect on chromosome pairing, while its application 40 h or more prior to MI induced a steady decline, culminating in a 40% reduction in chromosome pairing at about 80 h from MI. Between 48 and 35 h before MI (late premeiotic interphase to early zygotene) meiocytes underwent a period of active nucleolar fusion. The time, therefore, at which the colchicine sensitive aspects of chromosome pairing were completed coincided with the completion of nucleolar fusion. From comparison with other findings it was concluded that there is a colchicine sensitive bouquet stage which appears in leptotene and early zygotene; this bouquet is responsible for active nucleolar fusion and final close association between homologous chromosomes.

3.—The Cytology of the Parthenogenetic Australian Weevil Listroderes costirostris Schönh

1973 ◽  
Vol 69 (3) ◽  
pp. 71-89 ◽  
Author(s):  
Ann R. Sanderson
Keyword(s):  
Body Size ◽  
Chromosome Number ◽  
Polar Nucleus ◽  
Low Fertility ◽  
Arrested Development ◽  
Relationship Of ◽  
Bouquet Stage ◽  
The Relationship

SynopsisKaryograms prepared from ovarian and blastoderm cells of the parthenogenetic Australian Brown Vegetable Weevil demonstrate a consistent triploid condition with 30 chromosomes which can be grouped into 10 sets of homologues. Meiosis is replaced by a single mitotic-like division in which 30 univalent chromosomes, each composed of two chromatids, divide equationally between an ootid nucleus and a single polar nucleus. Prior to the differentiation of the oocytes a peculiar bouquet stage occurs in the cells of the end chamber of each ovariole, but the significance of this phase is not known. Arrested development in eggs from individuals of low fertility is investigated and the relationship of body size and chromosome number is discussed.

scholarly journals Chromosome 18 pairing behavior in human trisomic oocytes. Presence of an extra chromosome extends bouquet stage

Reproduction ◽  
2005 ◽  
Vol 129 (5) ◽  
pp. 565-575 ◽  
Author(s):  
I Roig ◽  
P Robles ◽  
R Garcia ◽  
I Martínez-Flores ◽  
Ll Cabero ◽  
...  
Keyword(s):  
Meiotic Prophase ◽  
Extra Chromosome ◽  
Fetal Life ◽  
Chromosome 18 ◽  
Synaptic Process ◽  
Complete Study ◽  
Pairing Behavior ◽  
Bouquet Stage ◽  
Axial Element ◽  
Made In

Little is known about the first meiotic prophase stages in the human female because these occur during fetal life, and only a few studies have addressed aneuploid human oocytes. In this paper, the synaptic process in the meiotic prophase in three 47, XX + 18 cases is analyzed. A complete study of the dynamics of centromeres and telomeres, cohesin core and synapsis development in aneuploid female meiosis was performed. Investigation of chromosome dynamics in prophase of trisomy 18 oocytes show that these events follow the major patterns seen earlier in euploid oocytes. However, there is a significant delay in the resolution of bouquet topology which could relate to the presence of a surplus chromosome 18 axial element in zygotene oocytes. Pachytene oocytes displayed normal synapsis among the three chromosome 18s. However, in some oocytes the surplus chromosome 18 core was aligned to the bivalent 18. As ataxia telangiectasia and Rad3 related kinase (ATR) has been described as a marker for late-pairing chromosomes in mice, ATR distribution was analyzed in human meiocytes –spermatocytes, euploid oocytes and trisomic oocytes. In contrast to the observations made in mice, no preferential staining for late-pairing chromosomes was observed in humans. In the cases studied, bivalent synapses progressed as in a normal ovary, contrasting with the hypothesis that a surplus chromosome can modify pairing of other chromosomes.

scholarly journals Telomeres act autonomously in maize to organize the meiotic bouquet from a semipolarized chromosome orientation

2002 ◽  
Vol 157 (2) ◽  
pp. 231-242 ◽  
Author(s):  
Peter M. Carlton ◽  
W. Zacheus Cande
Keyword(s):  
Large Scale ◽  
Nuclear Periphery ◽  
Small Region ◽  
Homologous Chromosomes ◽  
Cis Acting ◽  
Chromosome Architecture ◽  
Meiotic Chromosomes ◽  
Ring Chromosomes ◽  
Bouquet Stage ◽  
Chromosome Regions

During meiosis, chromosomes undergo large-scale reorganization to allow pairing between homologues, which is necessary for recombination and segregation. In many organisms, pairing of homologous chromosomes is accompanied, and possibly facilitated, by the bouquet, the clustering of telomeres in a small region of the nuclear periphery. Taking advantage of the cytological accessibility of meiosis in maize, we have characterized the organization of centromeres and telomeres throughout meiotic prophase. Our results demonstrate that meiotic centromeres are polarized prior to the bouquet stage, but that this polarization does not contribute to bouquet formation. By examining telocentric and ring chromosomes, we have tested the cis-acting requirements for participation in the bouquet. We find that: (a) the healed ends of broken chromosomes, which contain telomere repeats, can enter the bouquet; (b) ring chromosomes enter the bouquet, indicating that terminal position on a chromosome is not necessary for telomere sequences to localize to the bouquet; and (c) beginning at zygotene, the behavior of telomeres is dominant over any centromere-mediated chromosome behavior. The results of this study indicate that specific chromosome regions are acted upon to determine the organization of meiotic chromosomes, enabling the bouquet to form despite large-scale changes in chromosome architecture.

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