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Maria Jose De Souza - One of the best experts on this subject based on the ideXlab platform.

  • ommexecha virens thunberg 1824 and descampsacris serrulatum serville 1831 orthoptera ommexechidae karyotypes Constitutive Heterochromatin and nucleolar organizing regions
    Comparative Cytogenetics, 2011
    Co-Authors: D B Carvalho, Vilma Loreto, Marilia De Franca Rocha, A E B Silva, Maria Jose De Souza
    Abstract:

    Chromosomes of Ommexecha virens and Descampsacris serrulatum (Ommexechidae) were analyzed through conventional staining, C-banding, base specific fluorochromes, silver nitrate impregnation (AgNO3), and fluorescent in situ hybridization (FISH) with probe for 45S rDNA. The two species presented diploid number 2n= 23,X0 in males and acrocentric autosomes, except the pair one that presented submetacentric morphology. The X chromosome has distinct morphology in the two analyzed species, being a medium acrocentric in Ommexecha virens and large submetacentric in Descampsacris serrulatum. The C-banding revealed pericentromeric blocks of Constitutive Heterochromatin (CH) in all the chromosomes of Descampsacris serrulatum. For Ommexecha virens it was evidenced that the blocks of CH are preferentially located in the pericentromeric area (however some bivalents presents additional blocks) or in different positions. The staining with CMA3/DA/DAPI showed GC rich CH blocks (CMA3+) in some chromosomes of the two species. The nucleolar organizer regions (NORs) were located in the bivalents L2, S9, S10 of Ommexecha virens and M5, M6, M7, S11 of Descampsacris serrulatum. The FISH for rDNA showed coincident results with the pattern of active NORs revealed by AgNO3. This work presents the first chromosomal data, obtained through differential cytogenetics techniques in Ommexechidae, contributing to a better characterization of karyotypic evolution for this grasshopper family.

  • cytogenetic analysis of two coprophanaeus species scarabaeidae revealing wide Constitutive Heterochromatin variability and the largest number of 45s rdna sites among coleoptera
    Micron, 2010
    Co-Authors: Rita De Cassia De Moura, Sarah Gomes De Oliveira, Ana Emilia Barros E Silva, Maria Jose De Souza
    Abstract:

    The Coleopterans of Scarabaeinae clade presents Coprophanaeus (Megaphanaeus) ensifer and C. (Coprophanaeus) cyanescens (Scarabaeidae) when they are studied cytogenetically by different techniques. The species present symmetric karyotypes, diploid number of 2n = 20, and meta-submetacentric chromosomes. C. (M.) ensifer present an XY sex-determining mechanism and C. (C.) cyanescens an XYp parachute mechanism. Analysis of Constitutive Heterochromatin (CH) in the two species revealed the presence of diphasic autosomes, with log arm heterochromatics. Moreover, an additional heterochromatic block in four autosomal bivalents were observed in C. (M.) ensifer. CMA3/DA/DAPI fluorochrome staining detected CMA3 positive heterochromatic blocks restricted to the sex chromosomes in C. (C.) cyanescens, whereas in C. (M.) ensifer CMA3 positive pericentromeric blocks were present in all autosomes, in the Y chromosome and in the four additional heterochromatic blocks. DAPI staining was neutral in both species. Silver nitrate (AgNO3) staining was inefficient for the detection of the nucleolar organizer region (NORs), but showed affinity for the heterochromatic regions. Fluorescence in situ hybridization (FISH) revealed the presence of 45S rDNA sites in the terminal region of the three autosomal bivalents of C. (C.) cyanescens and in seven bivalents and the Y chromosome of C. (M.) ensifer. These results contribute to a better understanding of chromosome evolution in the genus Coprophanaeus, and demonstrate a wide CH variability and the largest number of ribosomal sites among Coleoptera.

  • chromosome study in schistocerca orthoptera acrididae cyrtacanthacridinae karyotypes and distribution patterns of Constitutive Heterochromatin and nucleolus organizer regions nors
    Genetics and Molecular Biology, 2007
    Co-Authors: Maria Jose De Souza, Natoniel Franklin De Melo
    Abstract:

    Chromosome analyses were performed in two grasshopper species of the genus Schistocerca, S. pallens and S. flavofasciata. Both species shared the same diploid number (2n = 23, X in males; 2n = 24, XX in females);and a conserved karyotype composed exclusively of acrocentric chromosomes, but differed in their distribution patterns of Constitutive Heterochromatin and nucleolus organizer regions (NORs). Constitutive Heterochromatin was located in the pericentromeric region of all chromosomes in both species. S. flavofasciata presented an additional C-band on the distal region of the long arm of a small autosome pair (S9). Nucleolus organizer regions (NORs), revealed by silver nitrate staining (Ag-NORs), were observed on a medium autosome pair (M5) in both species. S. pallens presented an additional NOR-bearing autosome (M6). The same sites were labeled after FISH with an rDNA probe in S. pallens cells.

  • a comparative cytogenetic analysis between the grasshopper species chromacris nuptialis and c speciosa romaleidae Constitutive Heterochromatin variability and rdna sites
    Genetica, 2005
    Co-Authors: Vilma Loreto, Natoniel Franklin De Melo, Eva Stadtler, Maria Jose De Souza
    Abstract:

    The chromosomes of Chromacris nuptialis and C. speciosa were comparatively analyzed using different cytogenetic techniques, in order to determine the level of karyotypic similarities and differences between the species. The results show similarities in chromosome number (2n = 23,X0) and acrocentric morphology. In some C. nuptialis individuals meiotic irregularities were detected involving the L2 bivalent. This bivalent was delayed and presented anaphasic bridges and other aberrations. Differences in Constitutive Heterochromatin (CH) patterns and composition were observed through C-banding and fluorochromes staining. Silver nitrate staining revealed a single medium nucleolar organizer regions (NORs) pair, per species. Differences were also observed in NORs location, which was pericentromeric in C. nuptialis and proximal in C. speciosa. FISH using an rDNA probe confirmed the existence of ribosomal sites coinciding with active regions visualized by silver nitrate. The possible implications of the karyotype differences observed between both species are discussed.

  • karyotype Constitutive Heterochromatin and nucleolar organizer regions nors in belosacris coccineipes acrididae leptysminae
    Genetics and Molecular Biology, 2000
    Co-Authors: Vilma Loreto, Maria Jose De Souza
    Abstract:

    Several techniques including C-banding, fluorochromes and silver staining were used to obtain information about Heterochromatin patterns in the grasshopper B. coccineipes. Conventional staining showed a karyotype with 2n = 23 chromosomes in males and 2n = 24 in females, as well as XO:XX sex determination and acrotelocentric chromosomes. The medium-sized X chromosome was heteropycnotic positive at the beginning of prophase I and negative in metaphase I. C-banding revealed heterochromatic blocks in the pericentromeric regions of all chromosomes. Silver nitrate staining in this species showed three small bivalents (S9-S11) as nucleolar organizers with NORs located in the pericentromeric regions. CMA3-positive blocks were seen in pericentromeric regions of pairs M6, S9, S10 and S11. Sequential staining with CMA3/AgNO3 revealed homology between the CMA3-positive bands and NORs of the bivalents S9, S10 and S11. The CMA3-positive block of the bivalent M6 could represent a latent secondary NOR. The results obtained permit us to distinguish two categories of the Constitutive Heterochromatin in B. coccineipes.

Jerome Dejardin - One of the best experts on this subject based on the ideXlab platform.

  • the molecular basis of the organization of repetitive dna containing Constitutive Heterochromatin in mammals
    Chromosome Research, 2017
    Co-Authors: Gohei Nishibuchi, Jerome Dejardin
    Abstract:

    Constitutive Heterochromatin is composed mainly of repetitive elements and represents the typical inert chromatin structure in eukaryotic cells. Approximately half of the mammalian genome is made of repeat sequences, such as satellite DNA, telomeric DNA, and transposable elements. As essential genes are not present in these regions, most of these repeat sequences were considered as junk DNA in the past. However, it is now clear that these regions are essential for chromosome stability and the silencing of neighboring genes. Genetic and biochemical studies have revealed that histone methylation at H3K9 and its recognition by Heterochromatin protein 1 represent the fundamental mechanism by which Heterochromatin forms. Although this molecular mechanism is highly conserved from yeast to human cells, its detailed epigenetic regulation is more complex and dynamic for each distinct Constitutive Heterochromatin structure in higher eukaryotes. It can also vary according to the developmental stage. Chromatin immunoprecipitation followed by sequencing (ChIP-seq) analysis is a powerful tool to investigate the epigenetic regulation of eukaryote genomes, but non-unique reads are usually discarded during standard ChIP-seq data alignment to reference genome databases. Therefore, specific methods to obtain global epigenetic information concerning repetitive elements are needed. In this review, we focus on such approaches and we summarize the latest molecular models for distinct Constitutive Heterochromatin types in mammals.

  • Constitutive Heterochromatin formation and transcription in mammals
    Epigenetics & Chromatin, 2015
    Co-Authors: Nehme Saksouk, Elisabeth Simboeck, Jerome Dejardin
    Abstract:

    Constitutive Heterochromatin, mainly formed at the gene-poor regions of pericentromeres, is believed to ensure a condensed and transcriptionally inert chromatin conformation. Pericentromeres consist of repetitive tandem satellite repeats and are crucial chromosomal elements that are responsible for accurate chromosome segregation in mitosis. The repeat sequences are not conserved and can greatly vary between different organisms, suggesting that pericentromeric functions might be controlled epigenetically. In this review, we will discuss how Constitutive Heterochromatin is formed and maintained at pericentromeres in order to ensure their integrity. We will describe the biogenesis and the function of main epigenetic pathways that are involved and how they are interconnected. Interestingly, recent findings suggest that alternative pathways could substitute for well-established pathways when disrupted, suggesting that Constitutive Heterochromatin harbors much more plasticity than previously assumed. In addition, despite of the heterochromatic nature of pericentromeres, there is increasing evidence for active and regulated transcription at these loci, in a multitude of organisms and under various biological contexts. Thus, in the second part of this review, we will address this relatively new aspect and discuss putative functions of pericentromeric expression.

Nathalie Beaujean - One of the best experts on this subject based on the ideXlab platform.

  • Induced pluripotent stem-induced cells show better Constitutive Heterochromatin remodeling and developmental potential after nuclear transfer than their parental cells
    Stem Cells and Development, 2012
    Co-Authors: Zichuan Liu, Haifeng Wan, Eryao Wang, Xiaoyang Zhao, Chenhui Ding, Shuya Zhou, Ling Shuai, Chunjing Feng, Qi Zhou, Nathalie Beaujean
    Abstract:

    Recently, reprogramming of somatic cells from a differentiated to pluripotent state by overexpression of specific external transcription factors has been accomplished. It has been widely speculated that an undifferentiated state may make donor cells more efficient for nuclear transfer. To test this hypothesis, we derived induced pluripotent stem cells (iPS cells) from several somatic cell lines: mouse embryonic fibroblast (MEF), adult tail tip fibroblast (TTF), and brain neural stem cells (NSCs). Three dimensional (3D)-fluorescent in situ hybridization (FISH) and quantitative-FISH (Q-FISH) were then used to evaluate Constitutive (pericentric and telomeric) Heterochromatin organization in these iPS cells and in their parental differentiated cells. Here, we show that important nuclear remodeling and telomeres rejuvenation occur in these iPS cells regardless of their parental origin. When we used these cells as donors for nuclear transfer, we produced live-born cloned mice at much higher rates with the iPS-induced cells than with the parental cell lines. Interestingly, we noticed that developmental potential after nuclear transfer could be correlated with telomere length of the donor cells. Altogether, our findings suggest that Constitutive Heterochromatin organization from differentiated somatic cells can be reprogrammed to the pluripotent state by induction of iPS cells, which in turn support nuclear transfer procedure quite efficiently.

  • Ring-Like Distribution of Constitutive Heterochromatin in Bovine Senescent Cells
    PloS one, 2011
    Co-Authors: Andrey Pichugin, Nathalie Beaujean, Xavier Vignon, Yegor S. Vassetzky
    Abstract:

    BACKGROUND: Cells that reach "Hayflick limit" of proliferation, known as senescent cells, possess a particular type of nuclear architecture. Human senescent cells are characterized by the presence of highly condensed senescent associated Heterochromatin foci (SAHF) that can be detected both by immunostaining for histone H3 three-methylated at lysine 9 (H3K9me3) and by DAPI counterstaining. METHODS: We have studied nuclear architecture in bovine senescent cells using a combination of immunofluorescence and 3D fluorescent in-situ hybridization (FISH). RESULTS: Analysis of Heterochromatin distribution in bovine senescent cells using fluorescent in situ hybridization for pericentric chromosomal regions, immunostaining of H3K9me3, centromeric proteins CENP A/B and DNA methylation showed a lower level of Heterochromatin condensation as compared to young cells. No SAHF foci were observed. Instead, we observed fibrous ring-like or ribbon-like Heterochromatin patterns that were undetectable with DAPI counterstaining. These Heterochromatin fibers were associated with nucleoli. CONCLUSIONS: Constitutive Heterochromatin in bovine senescent cells is organized in ring-like structures.

  • Dynamics of Constitutive Heterochromatin: two contrasted kinetics of genome restructuring in early cloned bovine embryos
    Reproduction, 2010
    Co-Authors: Andrey Pichugin, Xavier Vignon, Daniel Le Bourhis, Pierre Adenot, Gaetan Lehmann, Christophe Audouard, Jean-paul Renard, Nathalie Beaujean
    Abstract:

    Efficient reprograming of the donor cell genome in nuclear transfer (NT) embryos is linked to the ability of the embryos to sustain full-term development. As the nuclear architecture has recently emerged as a key factor in the regulation of gene expression, we questioned whether early bovine embryos obtained from transfer of cultured fibroblasts into enucleated oocytes would adopt an embryo-like nuclear organization. We studied the dynamics of Constitutive Heterochromatin in the stages prior to embryonic genome activation by distribution analysis of Heterochromatin protein CBX1 (HP1), centromeric proteins CENPA and CENPB, and histone H3 three-methylated at lysine 9. Then we applied descriptive, quantitative, and co-localization analyses. A dramatic reorganization of heterochromatic blocks of somatic donor cells was first observed in the late one-cell stage NT embryos. Then at two- and four-cell stages, we found two types of NT embryos: one displaying noncondensed Heterochromatin patches similar to IVF embryos, whereas the second type displayed condensed Heterochromatin blocks, normally observed in IVF embryos only after the eight-cell stage. These analyses discriminate for the first time two contrasted types of nuclear organization in NT embryos, which may correspond to different functional states of the nuclei. The relationship with the somatic nucleus reprograming efficiency is discussed.

  • trichostatin a treatment of cloned mouse embryos improves Constitutive Heterochromatin remodeling as well as developmental potential to term
    BMC Developmental Biology, 2009
    Co-Authors: Nathalie Beaujean, Walid E Maalouf, Zichuan Liu, Vincent Brochard, J P Renard, Pascale Debey
    Abstract:

    Genome reprogramming in early mouse embryos is associated with nuclear reorganization and particular features such as the peculiar distribution of centromeric and pericentric Heterochromatin during the first developmental stage. This zygote-specific Heterochromatin organization could be observed both in maternal and paternal pronuclei after natural fertilization as well as in embryonic stem (ES) cell nuclei after nuclear transfer suggesting that this particular type of nuclear organization was essential for embryonic reprogramming and subsequent development. Here, we show that remodeling into a zygotic-like organization also occurs after somatic cell nuclear transfer (SCNT), supporting the hypothesis that reorganization of Constitutive Heterochromatin occurs regardless of the source and differentiation state of the starting material. However, abnormal nuclear remodeling was frequently observed after SCNT, in association with low developmental efficiency. When transient treatment with the histone deacetylase inhibitor trichostatin A (TSA) was tested, we observed improved nuclear remodeling in 1-cell SCNT embryos that correlated with improved rates of embryonic development at subsequent stages. Together, the results suggest that proper organization of Constitutive Heterochromatin in early embryos is involved in the initial developmental steps and might have long term consequences, especially in cloning procedures.

Natoniel Franklin De Melo - One of the best experts on this subject based on the ideXlab platform.

  • Chromosome study in Schistocerca (Orthoptera-Acrididae-Cyrtacanthacridinae): karyotypes and distribution patterns of Constitutive Heterochromatin and nucleolus organizer regions (NORs).
    Genetics and Molecular Biology Ribeirão Preto v. 30 n. 1 p. 54-59 2007., 2018
    Co-Authors: M. J. De ,souza, Natoniel Franklin De Melo
    Abstract:

    Chromosome analyses were performed in two grasshopper species of the genus Schistocerca, S. pallens and S. flavofasciata. Both species shared the same diploid number (2n = 23, X in males; 2n = 24, XX in females); and a con- served karyotype composed exclusively of acrocentric chromosomes but differed in their distribution patterns of Constitutive Heterochromatin and nucleolus organizer regions (NORs). Constitutive Heterochromatin was located in the pericentromeric region of alI chromosomes in both species. S. flavofasciata presented an additional C-band on the distal region of the long arm of a small autosome pair (S9). Nucleolus organizer regions (NORs), revealed by silver nitrate staining (Ag-NORs), were observed on a medium autosome pair (M5) in both species. S. pallens presented an additional NOR-bearing autosome (M6). The same sites were labeled after FISH with an rDNA probe in S. pallens cells.bitstream/CPATSA/35066/1/OPB1025.pd

  • chromosome study in schistocerca orthoptera acrididae cyrtacanthacridinae karyotypes and distribution patterns of Constitutive Heterochromatin and nucleolus organizer regions nors
    Genetics and Molecular Biology, 2007
    Co-Authors: Maria Jose De Souza, Natoniel Franklin De Melo
    Abstract:

    Chromosome analyses were performed in two grasshopper species of the genus Schistocerca, S. pallens and S. flavofasciata. Both species shared the same diploid number (2n = 23, X in males; 2n = 24, XX in females);and a conserved karyotype composed exclusively of acrocentric chromosomes, but differed in their distribution patterns of Constitutive Heterochromatin and nucleolus organizer regions (NORs). Constitutive Heterochromatin was located in the pericentromeric region of all chromosomes in both species. S. flavofasciata presented an additional C-band on the distal region of the long arm of a small autosome pair (S9). Nucleolus organizer regions (NORs), revealed by silver nitrate staining (Ag-NORs), were observed on a medium autosome pair (M5) in both species. S. pallens presented an additional NOR-bearing autosome (M6). The same sites were labeled after FISH with an rDNA probe in S. pallens cells.

  • a comparative cytogenetic analysis between the grasshopper species chromacris nuptialis and c speciosa romaleidae Constitutive Heterochromatin variability and rdna sites
    Genetica, 2005
    Co-Authors: Vilma Loreto, Natoniel Franklin De Melo, Eva Stadtler, Maria Jose De Souza
    Abstract:

    The chromosomes of Chromacris nuptialis and C. speciosa were comparatively analyzed using different cytogenetic techniques, in order to determine the level of karyotypic similarities and differences between the species. The results show similarities in chromosome number (2n = 23,X0) and acrocentric morphology. In some C. nuptialis individuals meiotic irregularities were detected involving the L2 bivalent. This bivalent was delayed and presented anaphasic bridges and other aberrations. Differences in Constitutive Heterochromatin (CH) patterns and composition were observed through C-banding and fluorochromes staining. Silver nitrate staining revealed a single medium nucleolar organizer regions (NORs) pair, per species. Differences were also observed in NORs location, which was pericentromeric in C. nuptialis and proximal in C. speciosa. FISH using an rDNA probe confirmed the existence of ribosomal sites coinciding with active regions visualized by silver nitrate. The possible implications of the karyotype differences observed between both species are discussed.

Gilbert Bernier - One of the best experts on this subject based on the ideXlab platform.

  • the polycomb repressive complex 1 protein bmi1 is required for Constitutive Heterochromatin formation and silencing in mammalian somatic cells
    Journal of Biological Chemistry, 2016
    Co-Authors: Mohamed Abdouh, Roy Hanna, Jida El Hajjar, Anthony Flamier, Gilbert Bernier
    Abstract:

    Abstract The polycomb repressive complex 1 (PRC1), containing the core BMI1 and RING1A/B proteins, mono-ubiquitinylates histone H2A (H2Aub) and is associated with silenced developmental genes at facultative Heterochromatin. It is, however, assumed that the PRC1 is excluded from Constitutive Heterochromatin in somatic cells based on work performed on mouse embryonic stem cells and oocytes. We show here that BMI1 is required for Constitutive Heterochromatin formation and silencing in human and mouse somatic cells. BMI1 was highly enriched at intergenic and pericentric Heterochromatin, co-immunoprecipitated with the architectural Heterochromatin proteins HP1, DEK1, and ATRx, and was required for their localization. In contrast, BRCA1 localization was BMI1-independent and partially redundant with that of BMI1 for H2Aub deposition, Constitutive Heterochromatin formation, and silencing. These observations suggest a dynamic and developmentally regulated model of PRC1 occupancy at Constitutive Heterochromatin, and where BMI1 function in somatic cells is to stabilize the repetitive genome.