The total number of bases in all the chromosomes of a human cell is approximately six billion and individual chromosomes range from 50 to million bases. The DNA sequence for a single trait is called a gene. Each chromosome contains a few thousand genes, which range in size from a few thousand bases up to 2 million bases. During most of the cell cycle, interphase, the chromosomes are somewhat less condensed and are not visible as individual objects under the light microscope. Figure 4. Human Chr4 territories are less stable if the energy barrier against chain crossing is switched off.
Results Since there are no attractive interactions in our model of the chromatin fiber, the bent and kinked initial state is unstable and unfolds rapidly.
Figure 5. Discussion We have studied the decondensation, structure and dynamics of interphase chromosomes using Molecular Dynamics simulations of a bead-spring model of the 30 nm chromatin fiber. Figure 6. Three dimensional spatial trajectories of the centers of mass of the 4 simulated human Chr4. Design of the Initial Configuration Experimental evidence suggests that metaphase chromosomes are folded into loops 30— kbp long rosettes , arranged radially along the axis of the chromatid see [9] and references therein.
Details of the Simulations The simulations have been performed in a constant isotropic pressure ensemble. Acknowledgments AR thanks C. Svaneborg for stimulating discussions. References 1. Alberts B, et al. New York: Garland Science. Morph Jb — View Article Google Scholar 3.
Cremer T, Cremer C Rise, fall and resurrection of chromosome territories: a hystorical perspective. Part I. The rise of chromosome territories. Eur J Histochem — View Article Google Scholar 4. Nature — View Article Google Scholar 5. View Article Google Scholar 6. Part II.
Fall and resurrection of chromosome territories during the s to s. Part III. Chromosome territories and the functional nuclear architecture: experiments and models from the s to the present. View Article Google Scholar 7. New York: Oxford University Press.
Science — View Article Google Scholar 9. Sikorav JL, Jannink G Kinetics of chromosome condensation in the presence of topoisomerases—a phantom chain model. Biophys J — View Article Google Scholar Influence of persistence length. Phys Rev E — Cremer T, Cremer C Chromosome territories, nuclear architecture and gene regulation in mammalian cells. Nat Rev Genet 2: — Kreth G, Finsterle J, von Hase J, Cremer M, Cremer C Radial arrangement of chromosome territories in human cell nuclei: a computer model approach based on gene density indicates a probabilistic global positioning code.
Hum Mol Genet — PLoS Biol 3: e Marshall WF Order and disorder in the nucleus. Curr Biol R—R Lowenstein MG, Goddard TD, Sedat JW Long-range interphase chromosome organization in Drosophila: a study using color barcoded fluorescence in-situ hybridization and structural clustering analysis.
Mol Biol Cell — J Cell Biol 5— Trends Cell Biol — Macromolecules — J Chem Phys Jun S, Mulder B Entropy-driven spatial organization of highly confined polymers: lessons for the bacterial chromosome.
Phys Rev E J Mol Biol — J Chem Phys — Cook P Molecular biology: The organization of replication and transcription. Phys Rev Lett — Annu Rev Genet — Mol Cell Biol 4: — Nat Mater 4: — Cell — Ohnuki Y Structure of chromosomes. Morphological studies of spiral structure of human somatic chromosomes.
Chromosoma — New York: Academic Press. Chromosomes are copied replicated and dispersed as chromatin. The chromosomes number is 8 in an onion root cell during interphase. They have uncoiled to form long, thin strands.
Chromosomes are not visible during interphase. The chromosomes replicate during interphase in meiosis. Because the chromosomes are uncoiled.
Chromosomes replicate during interphase. Specifically it occurs during S-phase which is one of three phases in interphase.
The chromosomes are replicated during interphase. The S phase in the interphase. Chromosomes are copied in the interphase part of the cell cycleS phase would be the answer. It is during Interphase G1, S, G2 that they are copied.
SO dependant on your answers it's either interphase or S. The stage chromosomes duplicate is during interphase. Interphase is the first stage of the cell cycle when chromosomes become visible and are replicated. Chromosomes are copied in the interphase part of the cell cycle. The replication of the chromosomes occurs during interphase. Chromatin turn into chromosomes during interphase. Log in. Study now. See Answer. Best Answer. Study guides. Genetics 20 cards. Classically, I-FISH was suggested to be limited to analyses of specific genomic loci [ 2 , 3 , 7 , 13 ].
However, some modifications such as ICS-MCB allow to get a view of interphase chromosomes in their integrity [ 23 , 24 , 26 — 29 , 31 , 33 — 35 , 74 ].
As mentioned before, ICS-MCB still have a limitation that is referred to the possibility of studying only one homologous chromosome pair per analysis metaphase chromosomal analysis allows to visualize all chromosomes of a cell , being, however, the unique way to visualize the whole banded chromosome in a nucleus [ 23 , 33 ]. Therefore, no additional drawbacks can be attributed to these procedures during interphase molecular cytogenetic studies.
However, there are numerous possibilities to apply digital analysis for studying interphase chromosomes. These include, but are not restricted to, QFISH, analysis of signal co-localization oncocytogenetic studies of gene fusions because of translocations in interphase nuclei , ICS-MCB visualization of chromosomal structures , increasing of FISH result visibility, automatic signal detection [ 79 ]. The type of FISH result evaluation i. Table 2 gives such overview.
I-FISH with centromeric probes is highly applicable for different areas of biomedical research and diagnosis [ 7 , 10 , 13 , 20 — 22 , 30 , 35 , 41 , 58 — 60 , 81 , 82 ]. The most frequent application of the method is the identification of numerical chromosome abnormalities aneuploidy and polyploidy in interphase nuclei Figure 1.
Fortunately, such extreme heteromorphisms centromeric DNA variations are rare in the general population [ 32 , 35 , 59 , 84 — 86 ]. A normal diploid nucleus with two signals for chromosome 1 and chromosome 15; B monosomic nucleus with two signals for chromosome 1 and one signal for chromosome 15; C trisomic nucleus with two signals for chromosome 1 and three signals for chromosome 15; D normal diploid nucleus with two signals for chromosome 1, chromosome 9 and chromosome 16; E monosomic nucleus with two signals for chromosome 1 and chrosmome 9 and one signal for chromosome 16; F trisomic nucleus with two signals for chromosome 1 and chromosome 16 and three signals for chromosome 9; G triploid nucleus with three signals for chromosome 16 and chromosome 18; H tetraploid nucleus with two signals for chromosome X and chromosome Y; I tetraploid nucleus with two signals for chromosome X and chromosome Y, and four signals for chromosome 1.
Interphase molecular cytogenetic studies by I-FISH with site-specific probes are commonly applied in preimplantation, prenatal and postnatal diagnosis as well as in cancer cytogenetics Figure 2 [ 2 , 3 , 13 , 36 , 47 — 50 ].
Although repeatedly noted to be of significant importance for detecting gene fusions resulting from interchromosomal translocations cancer biomarkers [ 49 , 87 — 89 ] and to be useful for preimplantation diagnosis [ 48 — 50 ], such I-FISH modifications has considerable disadvantages. This has the potential to produce false-positive or false-negative data [ 7 , 28 ]. Additionally, it requires to use probes for "well-characterized" genomic DNA sequences i.
Simultaneous use of centromeric and site-specific probes in an mFISH assay Figure 3 is sometimes useful for diagnostics and survey of intercellular somatic genomic variations [ 7 , 20 , 28 , 46 , 48 ]. It is generally recognized that FISH chromosomal painting using wcp is completely useless for identification of number and structure of interphase chromosomes Figure 4 [ 3 , 7 , 10 , 13 , 33 , 35 , 80 ].
However, basic research of chromosome architecture in interphase is usually performed using I-FISH with wcp. These probes allows to visualize chromosome territories and their positioning relative to nuclear compartments Figure 4B [ 57 , 70 — 72 , 85 , 93 ]. For the last two decades, I-FISH-wcp approaches were almost the unique way to study genomic organization in interphase [ 72 ].
Nonetheless, these techniques are all limited in their abilities to paint chromosome territories volumes only Table 2 [ 33 ]. I-FISH with two wcp for chromosomes 7 and A ambiguous chromosome territories provide information neither about number of chromosomes nor about structure of chromosomes chromosome 7 -- green signal; chromosome 21 -- red signals , whereas this individual presented with regular unbalanced t 7;21 ; more details are given in Vorsanova et al.
To visualize a homologous pair of interphase chromosomes in their integrity, one has to generate MCB. Therefore, this I-FISH approach solves the long-standing limitation of cytogenetics that refers to obtaining metaphase chromosomes [ 23 , 31 — 35 ]. Figure 5 gives an example of aneuploidy detection in an intephase nucleus isolated from the Alzheimer's disease brain [ 28 ].
ICS-MCB can be widely applied for basic research of somatic genomic variations, chromosome structural and functional organization in interphase, supramolecular disease mechanisms [ 3 , 7 , 10 , 12 , 13 , 19 , 23 , 24 , 26 — 29 , 31 , 33 — 36 , 73 — 75 , 79 — 81 ]. Apparently, the sole disadvantage of this technique is the impossibility to analyze more than one homologous chromosome pair at once [ 23 , 33 ].
Monosomy loss of chromosome 21 in a nucleus isolated from the Alzheimer's disease brain. As we have already mentioned, differences of hybridization efficiency complicate simultaneous applications of different probe sets [ 7 ]. For instance, signals of site-specific probes can be missed because of high brightness of wcp or centromeric probe signals.
However, some interphase protocols, mostly associated with molecular oncocytogenetics, are proven to be valid for diagnostic purposes [ 1 , 13 , 36 , 87 , 88 ]. Additional source of numerous artifacts that can be considered as false-positive chromosome abnormalities in interphase is nuclear organization.
In this context, the most problematic pattern of chromosome arrangement in the nucleus is related to chromosomal loci associations [ 94 , 95 ]. Regardless frequent occurrence of related difficulties, the problem is easily solved by QFISH Figure 6E [ 23 , 24 , 28 , 32 , 35 , 95 ]. Figure 7 demonstrates Immuno-FISH used for studying interphase chromosomes in neuronal cells of the adult human brain [ 28 , 29 ]. After listing the most known methods of interphase molecular cytogenetics, it is to focus on their specific applications.
Currently, there are there main biomedical areas requiring the use of I-FISH: analysis of intranuclear chromosome genome organization; identification of somatic intercellular and intertissular genomic variations; molecular cytogenetic diagnosis.
Below, a brief description of these applications is given. Spatial chromosome organization in interphase has been repeatedly shown to be a driving force for numerous crucial intracellular processes. To get an integrated view of genome organization in interphase, numerous approaches should be applied.
There could be several applications of I-FISH approaches for interphase chromosome analysis on this occasion: i identification of chromosome positioning and its relation to other nuclear compartments nucleolus, Cajal bodies, nuclear speckles etc.
Additional complication of I-FISH analysis of spatial chromosome organization is associated with structural preservation of nuclei. It is to note, that some researchers report about dependence of fixation type on I-FISH results [ 72 , 93 ], whereas others do not [ 71 ]. The advantage of this approach is related to possibility of studying three-dimensional 3D preserved nuclei from any human tissue, whereas other 3D preservation techniques require specific conditions of cell cultivation.
Together, it is to conclude that comprehensive description of functional significance of nuclear organization requires application of almost all known interphase molecular cytogenetic techniques. During the last half decade, genomic variations -- a source of human healthy and pathological diversity -- have become a major focus of current biomedical research. Being involved in evolutionary and disease pathways, variations of the human genome are considered the main target of researches aimed to uncover disease mechanisms and species origins [ ].
Soon after description of high rate of interindividual genomic diversification, it has been hypothesized that related processes-- somatic genomic variations -- lie at the origin of intercellular genomic differences. Moreover, somatic variability of cellular genomes was proposed as a mechanism for complex human diseases [ 7 , 10 , 12 ].
The latter has been partially confirmed by high-resolution interphase molecular cytogenetic molecular neurocytogenetic studies of neurological and psychiatric diseases [ 7 , 20 — 29 ]. Altogether, this forms a basis for forthcoming researches in the field of single-cell biology.
All these achievements were the result of numerous developments in interphase molecular cytogenetics. To prove it, we would like to refer to determination of stochastic sporadic or background aneuploidy level in human tissues Table 3 [ 20 — 24 , 59 , 28 , 29 , 35 , 81 , — ].
Looking through these data, it is hard to avoid the conclusion that aneuploidy rates become more reasonable if high-resolution I-FISH approaches are applied.
Together, I-FISH can be proposed as a required addition for studying genomic variations at microscopic and submicroscopic levels. Molecular cytogenetic identification of chromosomal aberrations by I-FISH has been already mentioned in this review. Here, we would like to make some additional comments related to more specific problems of medical cytogenetics and to show again that studying chromosomes in interphase nuclei has profound effects on molecular cancer and prenatal diagnosis [ , ].
Here, we have preferred to describe several difficulties encountered during I-FISH introduction and usage for diagnostic purposes. Newly introduced interphase techniques i. ICS-MCB were used for research purposes only and, therefore, have not been tested for diagnostic validity. Despite of limiting practical application of these I-FISH protocols, related drawbacks can be easily eliminated by forthcoming studies. Another problem comes from the diagnosis of chromosomal mosaicism. There do not exist commonly accepted guidelines or criteria for mosaicism definition [ 7 , 10 , 35 ].
Regardless some attempts for details see [ 35 ] , there is still no consensus concerning this topic. The solution would be a large-scale study aimed to uncover somatic genomic variations in unaffected human tissues. Hopefully, similar studies have been already launched [ 20 — 24 , 59 , 28 , 29 , 35 , 81 ]. Finally, there are still no data or recommendations concerning correlation between metaphase and interphase diagnostic analysis of the same individual.
In other words, it is still poorly understood what data is more valid. The structural point of view insists that metaphase analysis of chromosomes is more precise. From the other hand, mosaics require large cell populations to be analyzed.
It becomes even more difficult to solve this problem when cases of complex, hidden cryptic or dynamic mosaicism are attempted to be described. Metaphase analysis in these case is indispensable for thorough definition of all cell lines, because simple I-FISH analyses are unable to precise a percentage of each cell line [ , ].
Moreover, some studies require additional data to obtain, i. It is widely accepted that molecular cytogenetic diagnosis should be performed using a panel of techniques [ 1 — 10 ]. It could be either a combination of molecular cytogenetic techniques that use different platforms i. Thus, regardless significant developments in the field of molecular interphase cytogenetics, I-FISH techniques remain an addition to metaphase cytogenetics or whole genome screening approaches based on array CGH.
The exception is few targeted assays for identification of known caner-associated translocations in interphase and preimplantation genetic diagnosis.
0コメント