The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
I F Zhimulev - One of the best experts on this subject based on the ideXlab platform.
-
Polytene Chromosomes reflect functional organization of the drosophila genome
Journal of Genetics and Breeding, 2019Co-Authors: Darya S Sidorenko, E S Belyaeva, S A Demakov, G V Pokholkova, Yu T Zykova, V A Khoroshko, Jan Larsson, I F ZhimulevAbstract:Polytene Chromosomes of Drosophila melanogaster are a convenient model for studying interphase Chromosomes of eukaryotes. They are giant in size in comparison with diploid cell Chromosomes and have a pattern of cross stripes resulting from the ordered chromatid arrangement. Each region of Polytene Chromosomes has a unique banding pattern. Using the model of four chromatin types that reveals domains of varying compaction degrees, we were able to correlate the physical and cytological maps of some Polytene chromosome regions and to show the main properties of genetic and molecular organization of bands and interbands, that we describe in this review. On the molecular map of the genome, the interbands correspond to decompacted aquamarine chromatin and 5’ ends of ubiquitously active genes. Gray bands contain lazurite and malachite chromatin, intermediate in the level of compaction, and, mainly, coding parts of genes. Dense black transcriptionally inactive bands are enriched in ruby chromatin. Localization of several dozens of interbands on the genome molecular map allowed us to study in detail their architecture according to the data of whole genome projects. The distribution of proteins and regulatory elements of the genome in the promoter regions of genes localized in the interbands shows that these parts of interbands are probably responsible for the formation of open chromatin that is visualized in Polytene Chromosomes as interbands. Thus, the permanent genetic activity of interbands and gray bands and the inactivity of genes in black bands are the basis of the universal banding pattern in the Chromosomes of all Drosophila tissues. The smallest fourth chromosome of Drosophila with an atypical protein composition of chromatin is a special case. Using the model of four chromatin states and fluorescent in situ hybridization, its cytological map was refined and the genomic coordinates of all bands and interbands were determined. It was shown that, in spite of the peculiarities of this chromosome, its band organization in general corresponds to the rest of the genome. Extremely long genes of different Drosophila Chromosomes do not fit the common scheme, since they can occupy a series of alternating bands and interbands (up to nine chromosomal structures) formed by parts of these genes.
-
border structure of intercalary heterochromatin bands of drosophila melanogaster Polytene Chromosomes
Doklady Biochemistry and Biophysics, 2018Co-Authors: V A Khoroshko, I F Zhimulev, Yu T Zykova, O O PopovaAbstract:The precise genomic localization of the borders of 62 intercalary heterochromatin bands in Drosophila Polytene Chromosomes was determined. A new type of bands containing chromatin of different states was identified. This type is a combination of the gray band and the intercalary heterochromatin band, creating a genetic structure that with a light microscope is identified as a continuous band. The border structure of such bands includes the coding regions of genes with ubiquitous activity.
-
banding patterns in drosophila melanogaster Polytene Chromosomes correlate with dna binding protein occupancy
BioEssays, 2012Co-Authors: I F Zhimulev, E S Belyaeva, Tatiana Yu Vatolina, S A DemakovAbstract:The most enigmatic feature of Polytene Chromosomes is their banding pattern, the genetic organization of which has been a very attractive puzzle for many years. Recent genome-wide protein mapping efforts have produced a wealth of data for the chromosome proteins of Drosophila cells. Based on their specific protein composition, the Chromosomes comprise two types of bands, as well as interbands. These differ in terms of time of replication and specific types of proteins. The interbands are characterized by their association with “active” chromatin proteins, nucleosome remodeling, and origin recognition complexes, and so they have three functions: acting as binding sites for RNA pol II, initiation of replication and nucleosome remodeling of short fragments of DNA. The borders and organization of the same band and interband regions are largely identical, irrespective of the cell type studied. This demonstrates that the banding pattern is a universal principle of the organization of interphase Polytene and non-Polytene Chromosomes. Editor's suggested further reading in BioEssays Caught in the act: Rapid, symbiont-driven evolutionAbstract Function and evolution of sex determination mechanisms, genes and pathways in insectsAbstract
-
identical functional organization of nonPolytene and Polytene Chromosomes in drosophila melanogaster
PLOS ONE, 2011Co-Authors: Tatyana Yu Vatolina, E S Belyaeva, S A Demakov, Olga V Demakova, Lidiya V Boldyreva, E B Kokoza, Valeriy F Semeshin, V N Babenko, Fedor P Goncharov, I F ZhimulevAbstract:Salivary gland Polytene Chromosomes demonstrate banding pattern, genetic meaning of which is an enigma for decades. Till now it is not known how to mark the band/interband borders on physical map of DNA and structures of Polytene Chromosomes are not characterized in molecular and genetic terms. It is not known either similar banding pattern exists in Chromosomes of regular diploid mitotically dividing nonPolytene cells. Using the newly developed approach permitting to identify the interband material and localization data of interband-specific proteins from modENCODE and other genome-wide projects, we identify physical limits of bands and interbands in small cytological region 9F13-10B3 of the X chromosome in D. melanogaster, as well as characterize their general molecular features. Our results suggests that the Polytene and interphase cell line Chromosomes have practically the same patterns of bands and interbands reflecting, probably, the basic principle of interphase chromosome organization. Two types of bands have been described in Chromosomes, early and late-replicating, which differ in many aspects of their protein and genetic content. As appeared, origin recognition complexes are located almost totally in the interbands of Chromosomes.
-
chromatin decompaction in the interbands of drosophila Polytene Chromosomes does not correlate with high transcription level
Russian Journal of Genetics, 2011Co-Authors: Evgeny Z Kvon, S A Demakov, I F ZhimulevAbstract:The search for correlation between structural organization of particular chromosome regions and their functions is among key directions of molecular cytogenetics. In this study, we used Polytene Chromosomes of Drosophila melanogaster as a convenient model for examining transcriptional activity of chromomeres (bands) and interchromomeres (interbands) in eukaryotic interphase Chromosomes. Using cloning of the interband DNA sequences and determination of the molecular limits for some interbands, we analyzed the transcriptional activity of these regions and compared the band and interband transcriptional activity in Polytene Chromosomes. Our results showed the absence of correlation between the decompacted state of the interbands examined and the levels of transcription observed in these regions.
E S Belyaeva - One of the best experts on this subject based on the ideXlab platform.
-
Polytene Chromosomes reflect functional organization of the drosophila genome
Journal of Genetics and Breeding, 2019Co-Authors: Darya S Sidorenko, E S Belyaeva, S A Demakov, G V Pokholkova, Yu T Zykova, V A Khoroshko, Jan Larsson, I F ZhimulevAbstract:Polytene Chromosomes of Drosophila melanogaster are a convenient model for studying interphase Chromosomes of eukaryotes. They are giant in size in comparison with diploid cell Chromosomes and have a pattern of cross stripes resulting from the ordered chromatid arrangement. Each region of Polytene Chromosomes has a unique banding pattern. Using the model of four chromatin types that reveals domains of varying compaction degrees, we were able to correlate the physical and cytological maps of some Polytene chromosome regions and to show the main properties of genetic and molecular organization of bands and interbands, that we describe in this review. On the molecular map of the genome, the interbands correspond to decompacted aquamarine chromatin and 5’ ends of ubiquitously active genes. Gray bands contain lazurite and malachite chromatin, intermediate in the level of compaction, and, mainly, coding parts of genes. Dense black transcriptionally inactive bands are enriched in ruby chromatin. Localization of several dozens of interbands on the genome molecular map allowed us to study in detail their architecture according to the data of whole genome projects. The distribution of proteins and regulatory elements of the genome in the promoter regions of genes localized in the interbands shows that these parts of interbands are probably responsible for the formation of open chromatin that is visualized in Polytene Chromosomes as interbands. Thus, the permanent genetic activity of interbands and gray bands and the inactivity of genes in black bands are the basis of the universal banding pattern in the Chromosomes of all Drosophila tissues. The smallest fourth chromosome of Drosophila with an atypical protein composition of chromatin is a special case. Using the model of four chromatin states and fluorescent in situ hybridization, its cytological map was refined and the genomic coordinates of all bands and interbands were determined. It was shown that, in spite of the peculiarities of this chromosome, its band organization in general corresponds to the rest of the genome. Extremely long genes of different Drosophila Chromosomes do not fit the common scheme, since they can occupy a series of alternating bands and interbands (up to nine chromosomal structures) formed by parts of these genes.
-
banding patterns in drosophila melanogaster Polytene Chromosomes correlate with dna binding protein occupancy
BioEssays, 2012Co-Authors: I F Zhimulev, E S Belyaeva, Tatiana Yu Vatolina, S A DemakovAbstract:The most enigmatic feature of Polytene Chromosomes is their banding pattern, the genetic organization of which has been a very attractive puzzle for many years. Recent genome-wide protein mapping efforts have produced a wealth of data for the chromosome proteins of Drosophila cells. Based on their specific protein composition, the Chromosomes comprise two types of bands, as well as interbands. These differ in terms of time of replication and specific types of proteins. The interbands are characterized by their association with “active” chromatin proteins, nucleosome remodeling, and origin recognition complexes, and so they have three functions: acting as binding sites for RNA pol II, initiation of replication and nucleosome remodeling of short fragments of DNA. The borders and organization of the same band and interband regions are largely identical, irrespective of the cell type studied. This demonstrates that the banding pattern is a universal principle of the organization of interphase Polytene and non-Polytene Chromosomes. Editor's suggested further reading in BioEssays Caught in the act: Rapid, symbiont-driven evolutionAbstract Function and evolution of sex determination mechanisms, genes and pathways in insectsAbstract
-
identical functional organization of nonPolytene and Polytene Chromosomes in drosophila melanogaster
PLOS ONE, 2011Co-Authors: Tatyana Yu Vatolina, E S Belyaeva, S A Demakov, Olga V Demakova, Lidiya V Boldyreva, E B Kokoza, Valeriy F Semeshin, V N Babenko, Fedor P Goncharov, I F ZhimulevAbstract:Salivary gland Polytene Chromosomes demonstrate banding pattern, genetic meaning of which is an enigma for decades. Till now it is not known how to mark the band/interband borders on physical map of DNA and structures of Polytene Chromosomes are not characterized in molecular and genetic terms. It is not known either similar banding pattern exists in Chromosomes of regular diploid mitotically dividing nonPolytene cells. Using the newly developed approach permitting to identify the interband material and localization data of interband-specific proteins from modENCODE and other genome-wide projects, we identify physical limits of bands and interbands in small cytological region 9F13-10B3 of the X chromosome in D. melanogaster, as well as characterize their general molecular features. Our results suggests that the Polytene and interphase cell line Chromosomes have practically the same patterns of bands and interbands reflecting, probably, the basic principle of interphase chromosome organization. Two types of bands have been described in Chromosomes, early and late-replicating, which differ in many aspects of their protein and genetic content. As appeared, origin recognition complexes are located almost totally in the interbands of Chromosomes.
-
Intercalary heterochromatin in Polytene Chromosomes of Drosophila melanogaster
Chromosoma, 2008Co-Authors: E S Belyaeva, E I Volkova, E. N. Andreyeva, S. N. Belyakin, I F ZhimulevAbstract:Intercalary heterochromatin consists of extended chromosomal domains which are interspersed throughout the euchromatin and contain silent genetic material. These domains comprise either clusters of functionally unrelated genes or tandem gene duplications and possibly stretches of noncoding sequences. Strong repression of genetic activity means that intercalary heterochromatin displays properties that are normally attributable to classic pericentric heterochromatin: high compaction, late replication and underreplication in Polytene Chromosomes, and the presence of heterochromatin-specific proteins. Late replication and underreplication occurs when the suppressor of underreplication protein is present in intercalary heterochromatic regions. Intercalary heterochromatin underreplication in Polytene Chromosomes results in free double-stranded ends of DNA molecules; ligation of these free ends is the most likely mechanism for ectopic pairing between intercalary heterochromatic and pericentric heterochromatic regions. No support has been found for the view that the frequency of chromosome aberrations is elevated in intercalary heterochromatin.
-
three distinct chromatin domains in telomere ends of Polytene Chromosomes in drosophila melanogaster tel mutants
Journal of Cell Science, 2005Co-Authors: Evgenia N Andreyeva, E S Belyaeva, G V Pokholkova, Valerii F Semeshin, I F ZhimulevAbstract:Drosophila melanogaster telomeric DNA is known to comprise two domains: the terminal tract of retrotransposons (HeT-A, TART and TAHRE) and telomere-associated sequences (TAS). Chromosome tips are capped by a protein complex, which is assembled on the chromosome ends independently of the underlying terminal DNA sequences. To investigate the properties of these domains in salivary gland Polytene Chromosomes, we made use of Tel mutants. Telomeres in this background are elongated owing to the amplification of a block of terminal retroelements. Supercompact heterochromatin is absent from the telomeres of Polytene Chromosomes: electron microscopy analysis identifies the telomeric cap and the tract of retroelements as a reticular material, having no discernible banding pattern, whereas TAS repeats appear as faint bands. According to the pattern of bound proteins, the cap, tract of retroelements and TAS constitute distinct and non-overlapping domains in telomeres. SUUR, HP2, SU(VAR)3-7 and H3Me3K27 localize to the cap region, as has been demonstrated for HP1. All these proteins are also found in pericentric heterochromatin. The tract of retroelements is associated with proteins characteristic for both heterochromatin (H3Me3K9) and euchromatin (H3Me3K4, JIL-1, Z4). The TAS region is enriched for H3Me3K27. PC and E(Z) are detected both in TAS and many intercalary heterochromatin regions. Telomeres complete replication earlier than heterochromatic regions. The frequency of telomeric associations in salivary gland Polytene Chromosomes does not depend on the SuUR gene dosage, rather it appears to be defined by the telomere length.
S A Demakov - One of the best experts on this subject based on the ideXlab platform.
-
Polytene Chromosomes reflect functional organization of the drosophila genome
Journal of Genetics and Breeding, 2019Co-Authors: Darya S Sidorenko, E S Belyaeva, S A Demakov, G V Pokholkova, Yu T Zykova, V A Khoroshko, Jan Larsson, I F ZhimulevAbstract:Polytene Chromosomes of Drosophila melanogaster are a convenient model for studying interphase Chromosomes of eukaryotes. They are giant in size in comparison with diploid cell Chromosomes and have a pattern of cross stripes resulting from the ordered chromatid arrangement. Each region of Polytene Chromosomes has a unique banding pattern. Using the model of four chromatin types that reveals domains of varying compaction degrees, we were able to correlate the physical and cytological maps of some Polytene chromosome regions and to show the main properties of genetic and molecular organization of bands and interbands, that we describe in this review. On the molecular map of the genome, the interbands correspond to decompacted aquamarine chromatin and 5’ ends of ubiquitously active genes. Gray bands contain lazurite and malachite chromatin, intermediate in the level of compaction, and, mainly, coding parts of genes. Dense black transcriptionally inactive bands are enriched in ruby chromatin. Localization of several dozens of interbands on the genome molecular map allowed us to study in detail their architecture according to the data of whole genome projects. The distribution of proteins and regulatory elements of the genome in the promoter regions of genes localized in the interbands shows that these parts of interbands are probably responsible for the formation of open chromatin that is visualized in Polytene Chromosomes as interbands. Thus, the permanent genetic activity of interbands and gray bands and the inactivity of genes in black bands are the basis of the universal banding pattern in the Chromosomes of all Drosophila tissues. The smallest fourth chromosome of Drosophila with an atypical protein composition of chromatin is a special case. Using the model of four chromatin states and fluorescent in situ hybridization, its cytological map was refined and the genomic coordinates of all bands and interbands were determined. It was shown that, in spite of the peculiarities of this chromosome, its band organization in general corresponds to the rest of the genome. Extremely long genes of different Drosophila Chromosomes do not fit the common scheme, since they can occupy a series of alternating bands and interbands (up to nine chromosomal structures) formed by parts of these genes.
-
banding patterns in drosophila melanogaster Polytene Chromosomes correlate with dna binding protein occupancy
BioEssays, 2012Co-Authors: I F Zhimulev, E S Belyaeva, Tatiana Yu Vatolina, S A DemakovAbstract:The most enigmatic feature of Polytene Chromosomes is their banding pattern, the genetic organization of which has been a very attractive puzzle for many years. Recent genome-wide protein mapping efforts have produced a wealth of data for the chromosome proteins of Drosophila cells. Based on their specific protein composition, the Chromosomes comprise two types of bands, as well as interbands. These differ in terms of time of replication and specific types of proteins. The interbands are characterized by their association with “active” chromatin proteins, nucleosome remodeling, and origin recognition complexes, and so they have three functions: acting as binding sites for RNA pol II, initiation of replication and nucleosome remodeling of short fragments of DNA. The borders and organization of the same band and interband regions are largely identical, irrespective of the cell type studied. This demonstrates that the banding pattern is a universal principle of the organization of interphase Polytene and non-Polytene Chromosomes. Editor's suggested further reading in BioEssays Caught in the act: Rapid, symbiont-driven evolutionAbstract Function and evolution of sex determination mechanisms, genes and pathways in insectsAbstract
-
identical functional organization of nonPolytene and Polytene Chromosomes in drosophila melanogaster
PLOS ONE, 2011Co-Authors: Tatyana Yu Vatolina, E S Belyaeva, S A Demakov, Olga V Demakova, Lidiya V Boldyreva, E B Kokoza, Valeriy F Semeshin, V N Babenko, Fedor P Goncharov, I F ZhimulevAbstract:Salivary gland Polytene Chromosomes demonstrate banding pattern, genetic meaning of which is an enigma for decades. Till now it is not known how to mark the band/interband borders on physical map of DNA and structures of Polytene Chromosomes are not characterized in molecular and genetic terms. It is not known either similar banding pattern exists in Chromosomes of regular diploid mitotically dividing nonPolytene cells. Using the newly developed approach permitting to identify the interband material and localization data of interband-specific proteins from modENCODE and other genome-wide projects, we identify physical limits of bands and interbands in small cytological region 9F13-10B3 of the X chromosome in D. melanogaster, as well as characterize their general molecular features. Our results suggests that the Polytene and interphase cell line Chromosomes have practically the same patterns of bands and interbands reflecting, probably, the basic principle of interphase chromosome organization. Two types of bands have been described in Chromosomes, early and late-replicating, which differ in many aspects of their protein and genetic content. As appeared, origin recognition complexes are located almost totally in the interbands of Chromosomes.
-
chromatin decompaction in the interbands of drosophila Polytene Chromosomes does not correlate with high transcription level
Russian Journal of Genetics, 2011Co-Authors: Evgeny Z Kvon, S A Demakov, I F ZhimulevAbstract:The search for correlation between structural organization of particular chromosome regions and their functions is among key directions of molecular cytogenetics. In this study, we used Polytene Chromosomes of Drosophila melanogaster as a convenient model for examining transcriptional activity of chromomeres (bands) and interchromomeres (interbands) in eukaryotic interphase Chromosomes. Using cloning of the interband DNA sequences and determination of the molecular limits for some interbands, we analyzed the transcriptional activity of these regions and compared the band and interband transcriptional activity in Polytene Chromosomes. Our results showed the absence of correlation between the decompacted state of the interbands examined and the levels of transcription observed in these regions.
-
functional organization of interbands in drosophila Polytene Chromosomes
Russian Journal of Genetics, 2010Co-Authors: S A Demakov, V F Semeshin, O V Andreenkov, M B Berkaeva, Yu T Vatolina, E I Volkova, Evgeny Z Kvon, I F ZhimulevAbstract:The functional organization of particular chromosome regions is tightly associated with their function in eukaryotic cells. Details of this association are among the most topical problems of modern genetics. The paper characterizes the results of recent research of the specifics of the genetic organization and chromatin decondensation in interbands of Drosophila Polytene Chromosomes. Data on functional heterogeneity of interbands are considered. Experimental findings point to a lack of correlation between the decondensed chromatin state and the observed transcription level in particular interbands. The DNA sequences responsible for the interband formation are principally identifiable via site-specific homologous FRT/FLP recombination between two P transposons contained in Chromosomes. The results allow a search for particular protein factors that are involved in the decondensed state of interbands and structural and functional differentiation of Polytene Chromosomes.
E I Volkova - One of the best experts on this subject based on the ideXlab platform.
-
functional organization of interbands in drosophila Polytene Chromosomes
Russian Journal of Genetics, 2010Co-Authors: S A Demakov, V F Semeshin, O V Andreenkov, M B Berkaeva, Yu T Vatolina, E I Volkova, Evgeny Z Kvon, I F ZhimulevAbstract:The functional organization of particular chromosome regions is tightly associated with their function in eukaryotic cells. Details of this association are among the most topical problems of modern genetics. The paper characterizes the results of recent research of the specifics of the genetic organization and chromatin decondensation in interbands of Drosophila Polytene Chromosomes. Data on functional heterogeneity of interbands are considered. Experimental findings point to a lack of correlation between the decondensed chromatin state and the observed transcription level in particular interbands. The DNA sequences responsible for the interband formation are principally identifiable via site-specific homologous FRT/FLP recombination between two P transposons contained in Chromosomes. The results allow a search for particular protein factors that are involved in the decondensed state of interbands and structural and functional differentiation of Polytene Chromosomes.
-
Intercalary heterochromatin in Polytene Chromosomes of Drosophila melanogaster
Chromosoma, 2008Co-Authors: E S Belyaeva, E I Volkova, E. N. Andreyeva, S. N. Belyakin, I F ZhimulevAbstract:Intercalary heterochromatin consists of extended chromosomal domains which are interspersed throughout the euchromatin and contain silent genetic material. These domains comprise either clusters of functionally unrelated genes or tandem gene duplications and possibly stretches of noncoding sequences. Strong repression of genetic activity means that intercalary heterochromatin displays properties that are normally attributable to classic pericentric heterochromatin: high compaction, late replication and underreplication in Polytene Chromosomes, and the presence of heterochromatin-specific proteins. Late replication and underreplication occurs when the suppressor of underreplication protein is present in intercalary heterochromatic regions. Intercalary heterochromatin underreplication in Polytene Chromosomes results in free double-stranded ends of DNA molecules; ligation of these free ends is the most likely mechanism for ectopic pairing between intercalary heterochromatic and pericentric heterochromatic regions. No support has been found for the view that the frequency of chromosome aberrations is elevated in intercalary heterochromatin.
-
intercalary heterochromatin in drosophila melanogaster Polytene Chromosomes and the problem of genetic silencing
Genetica, 2003Co-Authors: I F Zhimulev, E S Belyaeva, V F Semeshin, Dmitry E Koryakov, E I Volkova, S. N. Belyakin, Igor V Makunin, Vincenzo Pirrotta, Artyom A Alekseyenko, Evgeniya N AndreyevaAbstract:The morphological characteristics of intercalary heterochromatin (IH) are compared with those of other types of silenced chromatin in the Drosophila melanogaster genome: pericentric heterochromatin (PH) and regions subject to position effect variegation (PEV). We conclude that IH regions in Polytene Chromosomes are binding sites of silencing complexes such as PcG complexes and of SuUR protein. Binding of these proteins results in the appearance of condensed chromatin and late replication of DNA, which in turn may result in DNA underreplication. IH and PH as well as regions subject to PEV have in common the condensed chromatin appearance, the localization of specific proteins, late replication, underreplication in Polytene Chromosomes, and ectopic pairing.
-
the drosophila suppressor of underreplication protein binds to late replicating regions of Polytene Chromosomes
Genetics, 2002Co-Authors: Igor V Makunin, E S Belyaeva, E I Volkova, Vincenzo Pirrotta, E N Nabirochkina, I F ZhimulevAbstract:In many late-replicating euchromatic regions of salivary gland Polytene Chromosomes, DNA is underrepresented. A mutation in the SuUR gene suppresses underreplication and leads to normal levels of DNA polytenization in these regions. We identified the SuUR gene and determined its structure. In the SuUR mutant stock a 6-kb insertion was found in the fourth exon of the gene. A single SuUR transcript is present at all stages of Drosophila development and is most abundant in adult females and embryos. The SuUR gene encodes a protein of 962 amino acids whose putative sequence is similar to the N-terminal part of SNF2/SWI2 proteins. Staining of salivary gland Polytene Chromosomes with antibodies directed against the SuUR protein shows that the protein is localized mainly in late-replicating regions and in regions of intercalary and pericentric heterochromatin.
T D Kolesnikova - One of the best experts on this subject based on the ideXlab platform.
-
replication timing in drosophila and its peculiarities in Polytene Chromosomes
Journal of Genetics and Breeding, 2019Co-Authors: T D Kolesnikova, O V Antonenko, I V MakuninAbstract:Drosophila melanogaster is one of the popular model organisms in DNA replication studies. Since the 1960s, DNA replication of Polytene Chromosomes has been extensively studied by cytological methods. In the recent two decades, the progress in our understanding of DNA replication was associated with new techniques. Use of fluorescent dyes increased the resolution of cytological methods significantly. High-throughput methods allowed analysis of DNA replication on a genome scale, as well as its correlation with chromatin structure and gene activity. Precise mapping of the cytological structures of Polytene Chromosomes to the genome assembly allowed comparison of replication between Polytene Chromosomes and Chromosomes of diploid cells. New features of replication characteristic for D. melanogaster were described for both diploid and Polytene Chromosomes. Comparison of genomic replication profiles revealed a significant similarity between Drosophila and other well-studied eukaryotic species, such as human. Early replication is often confined to intensely transcribed gene-dense regions characterized by multiple replication initiation sites. Features of DNA replication in Drosophila might be explained by a compact genome. The organization of replication in Polytene Chromosomes has much in common with the organization of replication in Chromosomes in diploid cells. The most important feature of replication in Polytene Chromosomes is its low rate and the dependence of S-phase duration on many factors: external and internal, local and global. The speed of replication forks in D. melanogaster Polytene Chromosomes is affected by SUUR and Rift proteins. It is not known yet how universal the mechanisms associated with these factors are, but their study is very promising.
-
banding pattern of Polytene Chromosomes as a representation of universal principles of chromatin organization into topological domains
Biochemistry, 2018Co-Authors: T D KolesnikovaAbstract:: Drosophila Polytene Chromosomes are widely used as a model of eukaryotic interphase Chromosomes. The most noticeable feature of Polytene chromosome is transverse banding associated with alternation of dense stripes (dark or black bands) and light diffuse areas that encompass alternating less compact gray bands and interbands visible with an electron microscope. In recent years, several approaches have been developed to predict location of morphological structures of Polytene Chromosomes based on the distribution of proteins on the molecular map of Drosophila genome. Comparison of these structures with the results of analysis of the three-dimensional chromatin organization by the Hi-C method indicates that the morphology of Polytene Chromosomes represents direct visualization of the interphase nucleus spatial organization into topological domains. Compact black bands correspond to the extended topological domains of inactive chromatin, while interbands are the barriers between the adjacent domains. Here, we discuss the prospects of using Polytene Chromosomes to study mechanisms of spatial organization of interphase Chromosomes, as well as their dynamics and evolution.