Metaphase and chromomere banding are distinct entities of chromosome substructure

Haapala, O. K.

doi:10.1111/j.1601-5223.1984.tb00107.x

Cited by 9 publications

(2 citation statements)

References 24 publications

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“…Lacking Mg 2+ allows chromosome structure to be stretched and induced the changes of its length, as depicted by the results of chromosomes treated with buffer containing 0 mM Mg 2+ and those treated with EDTA. The elongation indicated the unwinding chromatid that reflected different condensation of chromatin (Haapala, 1984).…”

Section: Discussionmentioning

confidence: 99%

Insight into magnesium ions effect on chromosome banding and ultrastructure

Dwiranti

Mualifah

Kartapradja

et al. 2022

Microscopy Res & Technique

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Magnesium ion (Mg2+) plays a fundamental role in chromosome condensation which is important for genetic material segregation. Studies about the effects of Mg2+ on the overall chromosome structure have been reported. Nevertheless, its effects on the distribution of heterochromatin and euchromatin region have yet to be investigated. The aim of this study was to evaluate the effects of Mg2+ on the banding pattern and ultrastructure of the chromosome. Chromosome analysis was performed using the synchronized HeLa cells. The effect of Mg2+ was evaluated by subjecting the chromosomes to three different solutions, namely XBE5 (containing 5 mM Mg2+) as a control, XBE (0 mM Mg2+), and 1 mM EDTA as cations‐chelator. Chromosome banding was carried out using the GTL‐banding technique. The ultrastructure of the chromosomes treated with and without Mg2+ was further obtained using SEM. The results showed a condensed chromosome structure with a clear banding pattern when the chromosomes were treated with a buffer containing 5 mM Mg2+. In contrast, chromosomes treated with a buffer containing no Mg2+ and those treated with a cations‐chelator showed an expanded and fibrous structure with the lower intensity of the banding pattern. Elongation of the chromosome caused by decondensation resulted in the band splitting. The different ultrastructure of the chromosomes treated with and without Mg2+ was obvious under SEM. The results of this study further emphasized the role of Mg2+ on chromosome structure and gave insights into Mg2+ effects on the banding distribution and ultrastructure of the chromosome.

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Section: Discussionmentioning

confidence: 99%

Insight into magnesium ions effect on chromosome banding and ultrastructure

Dwiranti

Mualifah

Kartapradja

et al. 2022

Microscopy Res & Technique

View full text Add to dashboard Cite

show abstract

“…Lacking Mg 2+ allows chromosome structure to be stretched and induced the changes of its length, as depicted by the results of chromosomes treated with buffer containing 0 mM Mg 2+ and those treated with EDTA. The elongation indicated the unwinding chromatid that re ected different condensation of chromatin 17 .…”

Section: Discussionmentioning

confidence: 99%

The Effect of Magnesium Ions on Chromosome Structure: Insights from G-Banding

Dwiranti¹,

Kartapradja²,

Mualifah³

2020

Preprint

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Magnesium ion (Mg2+) plays a fundamental role in the chromosome condensation which is important for genetic material segregation. Studies about the effects of Mg2+ on the overall chromosome structure have been reported. Nevertheless, its effects on the distribution of heterochromatin and euchromatin region have yet to be investigated. This study was aimed to evaluate the effects of Mg2+ on the banding pattern of the chromosome structure. Chromosome analysis was performed using the GTL-banding technique on synchronized HeLa cells. The effect of Mg2+ was evaluated by subjecting the chromosomes to three different solutions, namely XBE5 (5 mM Mg2+) as a control, XBE (0 mM Mg2+), and 1 mM EDTA as cations chelator. The results showed a condensed chromosome structure with a clear banding pattern when it was treated with a buffer containing 5 mM Mg2+. In contrast, chromosomes treated with a buffer containing no Mg2+ and those treated with an ions chelator showed an expanded and fibrous structure with the lower intensity of the banding pattern. Elongation of the chromosome caused by decondensation resulted in the band splitting. The results of this study further emphasized the role of Mg2+ on chromosome structure and gave insights into Mg2+ effects on the banding distribution.

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Electron Tomography of Chromosome Structure

Engelhardt

2000

Encyclopedia of Analytical Chemistry

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Three‐dimensional (3‐D) structures at the molecular level of chromosomes and other cell structures are far beyond the reach of ordinary or confocal (3‐D) light microscopy (LM). The electron tomography method (ETM), i.e. transmission electron microscopy (TEM) tomography, is able to provide methods of 3‐D reconstruction of macromolecular assemblies, providing insights into the qualitative and quantitative spatial comprehension of macromolecular structures. ETM is a powerful method for developing reliable immunoelectron tomography (IET) and in situ hybridization analysis at the molecular level. With ETM the data are collected with TEM by taking tilt series, i.e. projection images from different viewing angles over the object. By combining such projections taken over a sufficient angular range (from 0 to ±60° manually, e.g. in 3° increments), a wholly transparent 3‐D representation of the object is recovered with necessary details. This requires the use of suitable computational methods. Automatic single‐axis tilt‐series data registration is possible today that will not only allow the collection of data with increments as small as 1°, for high‐resolution reconstructions of bulky whole mounts, but will also protect the specimen from electron beam damage (dose reduced by a factor of 10–100). Only automation of ETM procedures makes it possible to collect tilt series of cryo‐electron microscopy (EM) preparations of unfixed and unstained preparations in vitrified ice, i.e. fully hydrated samples close to the native state. Novel methods and tools for electron tomography are available that have been developed in different laboratories. Our electron tomography programs are automated to a high degree and therefore very fast and easy to use, in comparison with other program kits that are available. Specifically, our arsenal includes advanced tomography procedures based on the maximum entropy method (MEM) (e.g. 16‐bit gray‐scale MEM). A collection of preparative methods for preserving whole‐mounted chromosomes and cells for ETM studies has been developed. Examples of 3‐D reconstructions of human chromosomes are shown at high resolution (3–15 nm). It is considered that ETM allows 3‐D reconstructions, depending on the thickness of the preparation, with a resolution in the range 2.5–8.5 nm. In this respect, some success was recently made as we were able to detect nanoprobes (1.4‐nm immunogold markers) with the IET methods developed. ETM of chromosomes involving localized genes with in situ hybridization and gold‐labeling techniques is possible and would allow chromosome mapping in a 3‐D configuration with molecular resolution much more accurately than any standard EM method which are affected by superimposing gold labels with their accompanying structures. Concerning the structure and folding of the DNA in chromosomes, it is important to note that the linear sequence of bases in DNA is accompanied by higher level organizations, composed of loops, twists and folds in the long DNA chain, and, significantly, by DNA–protein interactions, e.g. nucleosomes, supranucleosomes, together with telomerase, topoisomerases and the new scaffold proteins [structural maintenance of proteins (SMC) family] recently described. These so‐called ‘higher order structures’ are certainly very much involved in the regulation of gene expression in chromosomes. Further, it is easy to realize that genes distantly located in the linear sequence map could in fact be topologically associated when DNA is folded in chromosomes, and thus mutually regulated. Sequencing of the genomes does not include and cannot reveal higher order structures. It is only with ETM that genome maps can be brought in relation to 3‐D molecular configurations, and it can be refined by combination with in situ hybridization to localize gene sequences and with IET to identify chromosomal proteins.

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Metaphase and chromomere banding are distinct entities of chromosome substructure

Cited by 9 publications

References 24 publications

Insight into magnesium ions effect on chromosome banding and ultrastructure

Insight into magnesium ions effect on chromosome banding and ultrastructure

The Effect of Magnesium Ions on Chromosome Structure: Insights from G-Banding

Electron Tomography of Chromosome Structure

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