Chromosome rotation and formation of synapsis

Parvinen, Martti; Söderström, Karl‐Ove

doi:10.1038/260534a0

Cited by 102 publications

(84 citation statements)

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“…Rotational movements of the entire chromatin have not been reported in yeast. In contrast, in rat, only rotational movements were reported and only during zygonema (13). Compared with yeasts, rat, and mouse, meiotic prophase chromosome motility patterns in maize seem more complex, exhibiting both concerted rotational movements of the entire chromatin as well as dynamic movements of individual chromosome segments.…”

Section: Diversity Of Meiotic Chromosome Dynamics Patterns Among Specmentioning

confidence: 93%

“…The detailed analyses of nuclear motility in early meiotic prophase in yeasts (8)(9)(10)(11)(12)20) and maize (this study), and the more fragmentary studies in mouse (14) and rat (13), have shown that patterns of meiotic chromosome movements exhibit immense diversity among species. In fission yeast, nuclear motility was highly dynamic throughout prophase and movements of all chromosomes were coordinated (11).…”

Section: Diversity Of Meiotic Chromosome Dynamics Patterns Among Specmentioning

confidence: 99%

“…Until now, in-depth examinations of meiotic prophase dynamics in live meiocytes have not been performed in multicellular eukaryotes. Only fragmentary observations have been conducted in mouse and rats, and they have shown only limited extent of chromosome motility (13,14).In maize, efforts to culture isolated meiocytes to observe chromosome motility have been largely unsuccessful. Although metaphase I and later meiocytes develop properly in culture (15), attempts to culture isolated meiocytes in early stages of meiotic prophase have failed (16).…”

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Live imaging of rapid chromosome movements in meiotic prophase I in maize

Sheehan

Pawlowski

2009

Proc. Natl. Acad. Sci. U.S.A.

110

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The ability of chromosomes to move across the nuclear space is essential for the reorganization of the nucleus that takes place in early meiotic prophase. Chromosome dynamics of prophase I have been studied in budding and fission yeasts, but little is known about this process in higher eukaryotes, where genomes and chromosomes are much larger and meiosis takes a longer time to complete. This knowledge gap has been mainly caused by difficulties in culturing isolated live meiocytes of multicellular eukaryotes. To study the nuclear dynamics during meiotic prophase in maize, we established a system to observe live meiocytes inside intact anthers. We found that maize chromosomes exhibited extremely dynamic and complex motility in zygonema and pachynema. The movement patterns differed dramatically between the two stages. Chromosome movements included rotations of the entire chromatin and movements of individual chromosome segments, which were mostly telomere-led. Chromosome motility was coincident with dynamic deformations of the nuclear envelope. Both, chromosome and nuclear envelope motility depended on actin microfilaments as well as tubulin. The complexity of the nuclear movements implies that several different mechanisms affect chromosome motility in early meiotic prophase in maize. We propose that the vigorous nuclear motility provides a mechanism for homologous loci to find each other during zygonema.chromosome dynamics ͉ cytogenetics ͉ meiosis ͉ cell biology I n early meiotic prophase, the nucleus undergoes a major spatial reorganization, which includes a general repositioning of chromatin and juxtaposition of homologous chromosomes (1). In many species, including maize, the nucleolus is located in the center of the nucleus during leptonema, and at the onset of zygonema, moves to a peripheral position (1, 2). Concurrently with the nucleus migration, all chromosome ends attach to the nuclear envelope (NE) and cluster on a single site forming the ''telomere bouquet'' (3, 4), which has been observed in most plants, animals, and fungi, including budding and fission yeasts, mouse, and maize. The telomeres remain clustered throughout zygonema. When the telomeres are clustered, centromeres are oriented in the opposite direction than the telomeres, resulting in a telomere-centromere polarization of the meiocyte nucleus. The presence of the bouquet coincides with pairing of homologous chromosomes (3, 5). In plants, mammals, and fungi, chromosome pairing depends upon the progression of meiotic recombination (5-7). However, a recombination-driven homology recognition mechanism can only operate across a relatively short distance, probably Ϸ1.2 m (6). In large-genome species, such as maize, where the zygotene nucleus is Ϸ20 m in diameter, this mechanism may not be sufficient to reach across the chromatin mass in the nucleus, even when the chromosomes are brought together by the bouquet (6). These constraints suggest that homologous chromosome segments must first be positioned close to each other, before the homology search...

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Section: Diversity Of Meiotic Chromosome Dynamics Patterns Among Specmentioning

confidence: 93%

Section: Diversity Of Meiotic Chromosome Dynamics Patterns Among Specmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Live imaging of rapid chromosome movements in meiotic prophase I in maize

Sheehan

Pawlowski

2009

Proc. Natl. Acad. Sci. U.S.A.

110

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“…Indeed, the extremely huge oscillatory motions of the horsetail motion of the nucleus are a specific phenomenon of S. pombe. However, recent studies in several eukaryotes have revealed several rotational and oscillatory motions of the nucleus during meiotic prophase, including in the rat, budding yeast Saccharomyces cerevisiae, and nematode Caenorhabditis elegans [11,[21][22][23]. We expect that such active motions of the nucleus might play important roles in the pairing between homologous loci generally, and plan to extend our arguments to these organisms in the future.…”

Section: Summary and Perspectivesmentioning

confidence: 99%

Excluded volume effect enhances the homology pairing of model chromosomes

Takamiya

Yamamoto

Isami

et al. 2016

NOLTA

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Abstract:To investigate the structural dynamics of the homology pairing of polymers, we modeled the scenario of homologous chromosome pairings during meiosis in Schizosaccharomyces pombe, one of the simplest model organisms of eukaryotes. We consider a simple model consisting of pairs of homologous polymers with the same structures that are confined in a cylindrical container, which represents the local parts of chromosomes contained in an elongated nucleus of S. pombe. Brownian dynamics simulations of this model showed that the excluded volume effects among non-homological chromosomes and the transitional dynamics of nuclear shape serve to enhance the pairing of homologous chromosomes.

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Nucleolar structure and synthetic activity during meiotic prophase and spermiogenesis in the rat

Schultz

Leblond

1990

Am. J. Anat.

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The ultrastructure of nucleoli was examined in developing rat spermatocytes and spermatids, with the help of serial sections. In addition, the radioautographic reaction of nucleoli as examined in rats sacrificed 1 hr after intratesticular injection of 3H(5')-uridine and taken as an index of the rate of synthesis of ribosomal RNA (rRNA). Primary spermatocytes from preleptotene to zygotene have small nucleoli typically composed of fibrillar centers, a fibrillar component, and a granular component, within which are narrow interstitial spaces. During early and mid-pachytene, nucleoli enlarge to about nine times their initial size, with the fibrillar and granular components forming an extensive network of cords--a nucleolonema--within which are wide interstitial spaces. Meanwhile, there appear structures identical to the granular component but distinct from nucleoli; they are referred to as extranucleolar granular elements. Finally, from late pachytene to the first maturation division, nucleoli undergo condensation, as shown by contraction of fibrillar centers into small clumps, while fibrillar and granular components condense and segregate from each other, with a gradual decrease in interstitial spaces. In secondary spermatocytes, nucleoli are compact and rather small, while in young spermatids they are also compact and even smaller. Nucleoli disappear in elongating spermatids. In 3H-uridine radioautographs, nucleolar label is weak in young primary spermatocytes, increases progressively during early pachytene, is strong by the end of mid pachytene, but gradually decreases during late pachytene up to the first maturation division. In secondary spermatocytes and spermatids, there is no significant nucleolar label. In conclusion, rRNA synthesis by nucleoli is low in young spermatocytes. During pachytene, while nucleoli enlarge and form a lacy nucleolonema, rRNA synthesis increases gradually to a high level by the end of mid pachytene. However, during the condensation and segregation of nucleolar components occurring from late pachytene onward, the synthesis gradually decreases and disappears. The small, compact spermatids arising from the second maturation division do not synthesize rRNA.

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Chromosome rotation and formation of synapsis

Cited by 102 publications

References 6 publications

Live imaging of rapid chromosome movements in meiotic prophase I in maize

Live imaging of rapid chromosome movements in meiotic prophase I in maize

Excluded volume effect enhances the homology pairing of model chromosomes

Nucleolar structure and synthetic activity during meiotic prophase and spermiogenesis in the rat

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