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Sample records for chromosome inactivation pattern

  1. [Assessing the inactivation pattern in chromosome X among symptomatic carriers and women with haemophilia].

    Science.gov (United States)

    Mundo-Ayala, Jessica Noemi; Jaloma-Cruz, Ana Rebeca

    2008-01-01

    X chromosome inactivation is a stochastic event that occurs early in female embryo development to achieve dosage compensation with males. Certain genetic mechanisms affect the normal process causing a skewed X inactivation pattern which has clinical relevance in female carriers of X-linked recessive disorders, like haemophilia. The most commonly used assay to evaluate the X inactivation pattern is the PCR amplification of the human androgen receptor gene (HUMARA). The use of this technique in bleeding carriers and women with haemophilia allows identifying if their hemorrhagic symptoms are due to an unfavourable lyonization. Furthermore, these studies are important for understanding the X chromosome inactivation process in humans.

  2. Three new loci for determining x chromosome inactivation patterns

    DEFF Research Database (Denmark)

    Bertelsen, Birgitte; Tümer, Zeynep; Ravn, Kirstine

    2011-01-01

    on two differentially methylated restriction enzyme sites (HpaII) and a polymorphic repeat located within this locus. Although highly informative, this locus is not always sufficient to evaluate the X-inactivation status in X-linked disorders. We have identified three new loci that can be used...... to determine XCI patterns in a methylation-sensitive PCR-based assay. All three loci contain polymorphic repeats and a methylation-sensitive restriction enzyme (HpaII) site, methylation of which was shown to correlate with XCI. DNA from 60 females was used to estimate the heterozygosity of these new loci...

  3. Dynamics of X Chromosome Inactivation

    NARCIS (Netherlands)

    F. Loos (Friedemann)

    2015-01-01

    markdownabstract__Abstract__ Dosage compensation evolved to account for the difference in expression of sex chromosome-linked genes. In mammals dosage compensation is achieved by inactivation of one X chromosome during early female embryogenesis in a process called X chromosome inactivation (XCI).

  4. X-chromosome inactivation patterns in monozygotic twins and sib pairs discordant for nonsyndromic cleft lip and/or palate

    DEFF Research Database (Denmark)

    Kimani, Jane W; Shi, Min; Daack-Hirsch, Sandra

    2007-01-01

    Nonsyndromic clefts of the lip and/or palate are common birth defects with a strong genetic component. Based on unequal gender ratios for clefting phenotypes, evidence for linkage to the X chromosome and the occurrence of several X-linked clefting syndromes, we investigated the role of skewed X...... of XCI was defined as the deviation in inactivation pattern from a 50:50 ratio. Our analysis revealed no significant difference in the degree of skewing between twin pairs (P = 0.3). However, borderline significant differences were observed in the sister pairs (P = 0.02), with the cleft lip with cleft......, particularly cleft lip and palate....

  5. Meiotic sex chromosome inactivation in the marsupial Monodelphis domestica.

    Science.gov (United States)

    Hornecker, Jacey L; Samollow, Paul B; Robinson, Edward S; Vandeberg, John L; McCarrey, John R

    2007-11-01

    In eutherian mammals, the X and Y chromosomes undergo meiotic sex chromosome inactivation (MSCI) during spermatogenesis in males. However, following fertilization, both the paternally (Xp) and maternally (Xm) inherited X chromosomes are active in the inner cell mass of the female blastocyst, and then random inactivation of one X chromosome occurs in each cell, leading to a mosaic pattern of X-chromosome activity in adult female tissues. In contrast, marsupial females show a nonrandom pattern of X chromosome activity, with repression of the Xp in all somatic tissues. Here, we show that MSCI also occurs during spermatogenesis in marsupials in a manner similar to, but more stable than that in eutherians. These findings support the suggestion that MSCI may have provided the basis for an early dosage compensation mechanism in mammals based solely on gametogenic events, and that random X-chromosome inactivation during embryogenesis may have evolved subsequently in eutherian mammals.

  6. X Chromosome inactivation pattern is not associated with interindividual variations in thyroid volume: a study of euthyroid danish female twins

    DEFF Research Database (Denmark)

    Brix, Thomas Heiberg; Hansen, Pia Skov; Bennedbak, Finn Noe

    2009-01-01

    Ahigher frequency of skewed X chromosome inactivation (XCI) is found in patients with autoimmune thyroid disease (AITD) than in controls. Although goitre is often present in AITD, a recent study failed to show an association between XCI and clinically overt nontoxic goitre. However, the etiology...... of overt goitre is complex, and the mechanisms influencing thyroid volume may involve fewer factors than the mechanisms underlying overt goitre. In order to examine the impact of XCI on thyroid volume in euthyroid females, we studied whether within cohort (n = 138) and within twin pair (n = 69) differences...

  7. Female meiotic sex chromosome inactivation in chicken

    NARCIS (Netherlands)

    S. Schoenmakers (Sam); E. Wassenaar (Evelyne); J.W. Hoogerbrugge (Jos); J.S.E. Laven (Joop); J.A. Grootegoed (Anton); W.M. Baarends (Willy)

    2009-01-01

    textabstractDuring meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI) leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (Z

  8. Chromosomal rearrangement interferes with meiotic X chromosome inactivation

    OpenAIRE

    Homolka, David; Ivanek, Robert; Capkova, Jana; Jansa, Petr; Forejt, Jiri

    2007-01-01

    Heterozygosity for certain mouse and human chromosomal rearrangements is characterized by the incomplete meiotic synapsis of rearranged chromosomes, by their colocalization with the XY body in primary spermatocytes, and by male-limited sterility. Previously, we argued that such X–autosomal associations could interfere with meiotic sex chromosome inactivation. Recently, supporting evidence has reported modifications of histones in rearranged chromosomes by a process called the meiotic silencin...

  9. Activation of X Chromosome Inactivation

    NARCIS (Netherlands)

    C.M. Maduro (Cheryl)

    2016-01-01

    markdownabstractIn mammals, males are the heterogametic sex having an X chromosome and a Y chromosome whereas females have two X chromosomes. Despite originating from an ancient homologous autosomal pair, the X and Y chromosome now differ greatly in size and gene content after ~180 MY of evolution.

  10. Recent insights into the regulation of X-chromosome inactivation

    Directory of Open Access Journals (Sweden)

    Valencia K

    2015-05-01

    Full Text Available Karmele Valencia, Anton Wutz Department of Biology, Institute of Molecular Health Sciences, Swiss Federal Institute of Technology Zurich, Zurich, Switzerland Abstract: X-chromosome inactivation (XCI is the mechanism by which mammals compensate gene dosage differences between males and females. XCI is required for female development and has implications for human disease. As a result, a single X chromosome is transcriptionally active in both male and female cells. Functional hemizygosity of the X chromosomes greatly predisposes to phenotypic consequences of mutations. In females, X chromosomes are randomly chosen to become inactivated leading to a mosaic pattern of cells expressing genes from either chromosome. This facilitates the masking of phenotypic consequences of heterozygous X-linked mutations. Skewing of XCI in favor of one chromosome can result in increased severity of disease symptoms, if the X chromosome with a gene mutation remains preferentially active. In addition, phenotypic masking of X-linked mutations is not always observed. Rett syndrome represents a paradigm of this statement. Dosage compensation can also mask some aspects of sex chromosome aneuploidies. X-chromosome aneuploidies include Klinefelter, Turner, and X-trisomy syndromes. In all these cases, a single active X chromosome is present. However, in those cases with two or more X chromosomes, some genes from the inactivated X chromosome escape from XCI becoming active. Therefore, dose imbalances of escape genes cause pathologies. Defects in the structure and silencing of the inactive X chromosome are further observed in human pluripotent stem cells and in certain tumors. Taken together, these findings suggest that aspects of XCI are relevant for a large number of human diseases. Here we review basic and clinical research on XCI with the aim of illustrating connections and highlighting opportunities for future investigation. Keywords: XCI, X-linked diseases, sex chromosome

  11. Sex chromosome inactivation in the male.

    Science.gov (United States)

    Yan, Wei; McCarrey, John R

    2009-10-01

    Mammalian females have two X chromosomes, while males have only one X plus a Y chromosome. In order to balance X-linked gene dosage between the sexes, one X chromosome undergoes inactivation during development of female embryos. This process has been termed X-chromosome inactivation (XCI). Inactivation of the single X chromosome also occurs in the male, but is transient and is confined to the late stages of first meiotic prophase during spermatogenesis. This phenomenon has been termed meiotic sex chromosome inactivation (MSCI). A substantial portion ( approximately 15-25%) of X-linked mRNA-encoding genes escapes XCI in female somatic cells. While no mRNA genes are known to escape MSCI in males, approximately 80% of X-linked miRNA genes have been shown to escape this process. Recent results have led to the proposal that the RNA interference mechanism may be involved in regulating XCI in female cells. We suggest that some MSCI-escaping miRNAs may play a similar role in regulating MSCI in male germ cells.

  12. Developmental regulation of X-chromosome inactivation.

    Science.gov (United States)

    Payer, Bernhard

    2016-08-01

    With the emergence of sex-determination by sex chromosomes, which differ in composition and number between males and females, appeared the need to equalize X-chromosomal gene dosage between the sexes. Mammals have devised the strategy of X-chromosome inactivation (XCI), in which one of the two X-chromosomes is rendered transcriptionally silent in females. In the mouse, the best-studied model organism with respect to XCI, this inactivation process occurs in different forms, imprinted and random, interspersed by periods of X-chromosome reactivation (XCR), which is needed to switch between the different modes of XCI. In this review, I describe the recent advances with respect to the developmental control of XCI and XCR and in particular their link to differentiation and pluripotency. Furthermore, I review the mechanisms, which influence the timing and choice, with which one of the two X-chromosomes is chosen for inactivation during random XCI. This has an impact on how females are mosaics with regard to which X-chromosome is active in different cells, which has implications on the severity of diseases caused by X-linked mutations.

  13. Chromosomal rearrangement interferes with meiotic X chromosome inactivation.

    Science.gov (United States)

    Homolka, David; Ivanek, Robert; Capkova, Jana; Jansa, Petr; Forejt, Jiri

    2007-10-01

    Heterozygosity for certain mouse and human chromosomal rearrangements is characterized by the incomplete meiotic synapsis of rearranged chromosomes, by their colocalization with the XY body in primary spermatocytes, and by male-limited sterility. Previously, we argued that such X-autosomal associations could interfere with meiotic sex chromosome inactivation. Recently, supporting evidence has reported modifications of histones in rearranged chromosomes by a process called the meiotic silencing of unsynapsed chromatin (MSUC). Here, we report on the transcriptional down-regulation of genes within the unsynapsed region of the rearranged mouse chromosome 17, and on the subsequent disturbance of X chromosome inactivation. The partial transcriptional suppression of genes in the unsynapsed chromatin was most prominent prior to the mid-pachytene stage of primary spermatocytes. Later, during the mid-late pachytene, the rearranged autosomes colocalized with the XY body, and the X chromosome failed to undergo proper transcriptional silencing. Our findings provide direct evidence on the MSUC acting at the mRNA level, and implicate that autosomal asynapsis in meiosis may cause male sterility by interfering with meiotic sex chromosome inactivation.

  14. Female meiotic sex chromosome inactivation in chicken.

    Science.gov (United States)

    Schoenmakers, Sam; Wassenaar, Evelyne; Hoogerbrugge, Jos W; Laven, Joop S E; Grootegoed, J Anton; Baarends, Willy M

    2009-05-01

    During meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI) leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW), whereas males have the homogametic ZZ constitution. During chicken oogenesis, the heterologous ZW pair reaches a state of complete heterologous synapsis, and this might enable maintenance of transcription of Z- and W chromosomal genes during meiotic prophase. Herein, we show that the ZW pair is transiently silenced, from early pachytene to early diplotene using immunocytochemistry and gene expression analyses. We propose that ZW inactivation is most likely achieved via spreading of heterochromatin from the W on the Z chromosome. Also, persistent meiotic DNA double-strand breaks (DSBs) may contribute to silencing of Z. Surprisingly, gammaH2AX, a marker of DSBs, and also the earliest histone modification that is associated with XY body formation in mammalian and marsupial spermatocytes, does not cover the ZW during the synapsed stage. However, when the ZW pair starts to desynapse, a second wave of gammaH2AX accumulates on the unsynapsed regions of Z, which also show a reappearance of the DSB repair protein RAD51. This indicates that repair of meiotic DSBs on the heterologous part of Z is postponed until late pachytene/diplotene, possibly to avoid recombination with regions on the heterologously synapsed W chromosome. Two days after entering diplotene, the Z looses gammaH2AX and shows reactivation. This is the first report of meiotic sex chromosome inactivation in a species with female heterogamety, providing evidence that this mechanism is not specific to spermatogenesis. It also indicates the presence of an evolutionary force that drives meiotic sex chromosome inactivation independent of the final achievement of synapsis.

  15. Female meiotic sex chromosome inactivation in chicken.

    Directory of Open Access Journals (Sweden)

    Sam Schoenmakers

    2009-05-01

    Full Text Available During meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW, whereas males have the homogametic ZZ constitution. During chicken oogenesis, the heterologous ZW pair reaches a state of complete heterologous synapsis, and this might enable maintenance of transcription of Z- and W chromosomal genes during meiotic prophase. Herein, we show that the ZW pair is transiently silenced, from early pachytene to early diplotene using immunocytochemistry and gene expression analyses. We propose that ZW inactivation is most likely achieved via spreading of heterochromatin from the W on the Z chromosome. Also, persistent meiotic DNA double-strand breaks (DSBs may contribute to silencing of Z. Surprisingly, gammaH2AX, a marker of DSBs, and also the earliest histone modification that is associated with XY body formation in mammalian and marsupial spermatocytes, does not cover the ZW during the synapsed stage. However, when the ZW pair starts to desynapse, a second wave of gammaH2AX accumulates on the unsynapsed regions of Z, which also show a reappearance of the DSB repair protein RAD51. This indicates that repair of meiotic DSBs on the heterologous part of Z is postponed until late pachytene/diplotene, possibly to avoid recombination with regions on the heterologously synapsed W chromosome. Two days after entering diplotene, the Z looses gammaH2AX and shows reactivation. This is the first report of meiotic sex chromosome inactivation in a species with female heterogamety, providing evidence that this mechanism is not specific to spermatogenesis. It also indicates the presence of an evolutionary force that drives meiotic sex chromosome inactivation independent of the final achievement of synapsis.

  16. Human male meiotic sex chromosome inactivation.

    Science.gov (United States)

    de Vries, Marieke; Vosters, Sanne; Merkx, Gerard; D'Hauwers, Kathleen; Wansink, Derick G; Ramos, Liliana; de Boer, Peter

    2012-01-01

    In mammalian male gametogenesis the sex chromosomes are distinctive in both gene activity and epigenetic strategy. At first meiotic prophase the heteromorphic X and Y chromosomes are placed in a separate chromatin domain called the XY body. In this process, X,Y chromatin becomes highly phosphorylated at S139 of H2AX leading to the repression of gonosomal genes, a process known as meiotic sex chromosome inactivation (MSCI), which has been studied best in mice. Post-meiotically this repression is largely maintained. Disturbance of MSCI in mice leads to harmful X,Y gene expression, eventuating in spermatocyte death and sperm heterogeneity. Sperm heterogeneity is a characteristic of the human male. For this reason we were interested in the efficiency of MSCI in human primary spermatocytes. We investigated MSCI in pachytene spermatocytes of seven probands: four infertile men and three fertile controls, using direct and indirect in situ methods. A considerable degree of variation in the degree of MSCI was detected, both between and within probands. Moreover, in post-meiotic stages this variation was observed as well, indicating survival of spermatocytes with incompletely inactivated sex chromosomes. Furthermore, we investigated the presence of H3K9me3 posttranslational modifications on the X and Y chromatin. Contrary to constitutive centromeric heterochromatin, this heterochromatin marker did not specifically accumulate on the XY body, with the exception of the heterochromatic part of the Y chromosome. This may reflect the lower degree of MSCI in man compared to mouse. These results point at relaxation of MSCI, which can be explained by genetic changes in sex chromosome composition during evolution and candidates as a mechanism behind human sperm heterogeneity.

  17. Human male meiotic sex chromosome inactivation.

    Directory of Open Access Journals (Sweden)

    Marieke de Vries

    Full Text Available In mammalian male gametogenesis the sex chromosomes are distinctive in both gene activity and epigenetic strategy. At first meiotic prophase the heteromorphic X and Y chromosomes are placed in a separate chromatin domain called the XY body. In this process, X,Y chromatin becomes highly phosphorylated at S139 of H2AX leading to the repression of gonosomal genes, a process known as meiotic sex chromosome inactivation (MSCI, which has been studied best in mice. Post-meiotically this repression is largely maintained. Disturbance of MSCI in mice leads to harmful X,Y gene expression, eventuating in spermatocyte death and sperm heterogeneity. Sperm heterogeneity is a characteristic of the human male. For this reason we were interested in the efficiency of MSCI in human primary spermatocytes. We investigated MSCI in pachytene spermatocytes of seven probands: four infertile men and three fertile controls, using direct and indirect in situ methods. A considerable degree of variation in the degree of MSCI was detected, both between and within probands. Moreover, in post-meiotic stages this variation was observed as well, indicating survival of spermatocytes with incompletely inactivated sex chromosomes. Furthermore, we investigated the presence of H3K9me3 posttranslational modifications on the X and Y chromatin. Contrary to constitutive centromeric heterochromatin, this heterochromatin marker did not specifically accumulate on the XY body, with the exception of the heterochromatic part of the Y chromosome. This may reflect the lower degree of MSCI in man compared to mouse. These results point at relaxation of MSCI, which can be explained by genetic changes in sex chromosome composition during evolution and candidates as a mechanism behind human sperm heterogeneity.

  18. Identification of novel RFLPs in the vicinity of CpG islands in Xq28: application to the analysis of the pattern of X chromosome inactivation.

    Science.gov (United States)

    Maestrini, E; Rivella, S; Tribioli, C; Rocchi, M; Camerino, G; Santachiara-Benerecetti, S; Parolini, O; Notarangelo, L D; Toniolo, D

    1992-01-01

    Probes for CpG islands were cloned from the distal long arm of the human X chromosome; three of them were found to be polymorphic. A HindIII RFLP was identified by the probe 2-25 (DXS606), and it was mapped to the Xq27-Xq28 boundary. Probes 2-19 (DXS605) and 2-55 (DXS707), which identify EcoRI and MspI polymorphisms, respectively, have been mapped to the distal part of Xq28, in the G6PD-RCP/GCP gene region. Probe 2-19 has been further localized about 16 kb from the 3' end of the G6PD gene. The new RFLPs may be useful for the precise mapping of the many disease genes localized in this part of the human X chromosome. Probe 2-19 is highly informative, and it has been studied in greater detail. Using the methylation-sensitive rare-cutter enzyme EagI in conjunction with the polymorphic EcoRI site, we were able to demonstrate that the RFLP may be used both to study randomness of X chromosome inactivation and for carrier detection in X-linked syndromes where nonrandom X inactivation occurs. It is conceivable that the combined use of 2-19 and of the probes described so far (pSPT-PGK and M27 beta) will make analysis of X inactivation feasible in virtually every female.

  19. Identification of novel RFLPs in the vicinity of CpG islands in Xq28: Application to the analysis of the pattern of X chromosome inactivation

    Energy Technology Data Exchange (ETDEWEB)

    Camerino, G.; Santachiara-Benerecetti, S. (Univ. di Pavia (Italy)); Rocchi, M. (Univ. di Bari (Italy)); Parolini, O.; Notarangelo, L.D. (Univ. di Brecscia (Italy)); Maestrini, E.; Rivella, S.; Tribioli, C.; Toniolo, D.

    1992-01-01

    Probes of CpG islands were cloned from the distal long arm of the human X chromosome; three of them were found to be polymorphic. A HindIII RFLP was identified by the probe 2-25 (DXS606), and it was mapped to the Xq27-Xq28 boundary. Probes 2-19 (DXS605) and 2-55 (DXS707), which identify EcoRI and MspI polymorphisms, respectively, have been mapped to the distal part of Xq28, in the G6PD-RCP/GCP gene region. Probe 2-19 has been further localized about 16 kb from the 3{prime} end of the G6PD gene. The new RFLPs may be useful for the precise mapping of the many disease genes localized in this part of the human X chromosome. Using the methylation-sensitive rare-cutter enzyme EagI in conjunction with the polymorphic EcoRI site, the authors were able to demonstrate that the RFLP may be used both to study randomness of X chromosome inactivation and for carrier detection in X-linked syndromes where nonrandom X inactivation occurs. It is conceivable that the combined use of 2-19 and of the probes described so far (pSPT-PGK and M27{beta}) will make analysis of X inactivation feasible in virtually every female.

  20. Meiotic sex chromosome inactivation in Drosophila.

    Science.gov (United States)

    Vibranovski, Maria D

    2014-01-01

    In several different taxa, there is indubitable evidence of transcriptional silencing of the X and Y chromosomes in male meiotic cells of spermatogenesis. However, the so called meiotic sex chromosome inactivation (MSCI) has been recently a hot bed for debate in Drosophila melanogaster. This review covers cytological and genetic observations, data from transgenic constructs with testis-specific promoters, global expression profiles obtained from mutant, wild-type, larvae and adult testes as well as from cells of different stages of spermatogenesis. There is no dispute on that D. melanogaster spermatogenesis presents a down-regulation of X chromosome that does not result from the lack of dosage compensation. However, the issue is currently focused on the level of reduction of X-linked expression, the precise time it occurs and how many genes are affected. The deep examination of data and experiments in this review exposes the limitations intrinsic to the methods of studying MSCI in D. melanogaster. The current methods do not allow us to affirm anything else than the X chromosome down-regulation in meiosis (MSCI). Therefore, conclusion about level, degree or precise timing is inadequate until new approaches are implemented to know the details of MSCI or other processes involved for D. melanogaster model.

  1. Strong purifying selection at genes escaping X chromosome inactivation.

    Science.gov (United States)

    Park, Chungoo; Carrel, Laura; Makova, Kateryna D

    2010-11-01

    To achieve dosage balance of X-linked genes between mammalian males and females, one female X chromosome becomes inactivated. However, approximately 15% of genes on this inactivated chromosome escape X chromosome inactivation (XCI). Here, using a chromosome-wide analysis of primate X-linked orthologs, we test a hypothesis that such genes evolve under a unique selective pressure. We find that escape genes are subject to stronger purifying selection than inactivated genes and that positive selection does not significantly affect the evolution of these genes. The strength of selection does not differ between escape genes with similar versus different expression levels in males versus females. Intriguingly, escape genes possessing Y homologs evolve under the strongest purifying selection. We also found evidence of stronger conservation in gene expression levels in escape than inactivated genes. We hypothesize that divergence in function and expression between X and Y gametologs is driving such strong purifying selection for escape genes.

  2. X chromosome inactivation and X-linked mental retardation

    Energy Technology Data Exchange (ETDEWEB)

    Willard, H.F. [Case Western Reserve Univ. School of Medicine, Cleveland, OH (United States)]|[Univ. Hospitals of Cleveland, OH (United States)

    1996-07-12

    The expression of X-linked genes in females heterozygous for X-linked defects can be modulated by epigenetic control mechanisms that constitute the X chromosome inactivation pathway. At least four different effects have been found to influence, in females, the phenotypic expression of genes responsible for X-linked mental retardation (XLMR). First, non-random X inactivation, due either to stochastic or genetic factors, can result in tissues in which one cell type (for example, that in which the X chromosome carrying a mutant XLMR gene is active) dominates, instead of the normal mosaic cell population expected as a result of random X inactivation. Second, skewed inactivation of the normal X in individuals carrying a deletion of part of the X chromosome has been documented in a number of mentally retarded females. Third, functional disomy of X-linked genes that are expressed inappropriately due to the absence of X inactivation has been found in mentally retarded females with structurally abnormal X chromosomes that do not contain the X inactivation center. And fourth, dose-dependent overexpression of X-linked genes that normally {open_quotes}escape{close_quotes} X inactivation may account for the mental and developmental delay associated with increasing numbers of otherwise inactive X chromosomes in individuals with X chromosome aneuploidy. 53 refs., 1 fig.

  3. MAOA and GYG2 are submitted to X chromosome inactivation in human fibroblasts.

    Science.gov (United States)

    Stabellini, Raquel; Vasques, Luciana R; de Mello, Joana Carvalho Moreira; Hernandes, Lys Molina; Pereira, Lygia V

    2009-08-16

    X chromosome inactivation (XCI) is a comprehensively studied phenomenon that helped to highlight the heritable nature of epigenetic modifications. Although it consists of the transcriptional inactivation of a whole X chromosome in females, some genes escape this process and present bi-allelic expression. Using human fibroblasts with skewed inactivation, we determined allele-specific expression of two X-linked genes previously described to escape XCI in rodent/human somatic cell hybrids, MAOA and GYG2, and the pattern of DNA methylation of their 5' end. Results from these complementary methodologies let us to conclude that both genes are subjected to X inactivation in normal human fibroblasts, indicating that hybrid cells are not an adequate system for studying epigenotypes. We emphasize the need of an analysis of XCI in normal human cell lines, helping us to determine more precisely which X-linked genes contribute to differences among genders and to the phenotypes associated with sex chromosomes aneuploidies.

  4. X chromosome inactivation is initiated in human preimplantation embryos

    NARCIS (Netherlands)

    van den Berg, Ilse M; Laven, Joop S E; Stevens, Mary; Jonkers, Iris; Galjaard, Robert-Jan; Gribnau, Joost; van Doorninck, J Hikke

    2009-01-01

    X chromosome inactivation (XCI) is the mammalian mechanism that compensates for the difference in gene dosage between XX females and XY males. Genetic and epigenetic regulatory mechanisms induce transcriptional silencing of one X chromosome in female cells. In mouse embryos, XCI is initiated at the

  5. Unique sex chromosome systems in Ellobius: How do male XX chromosomes recombine and undergo pachytene chromatin inactivation?

    Science.gov (United States)

    Matveevsky, Sergey; Bakloushinskaya, Irina; Kolomiets, Oxana

    2016-07-18

    Most mammalian species have heteromorphic sex chromosomes in males, except for a few enigmatic groups such as the mole voles Ellobius, which do not have the Y chromosome and Sry gene. The Ellobius (XX ♀♂) system of sex chromosomes has no analogues among other animals. The structure and meiotic behaviour of the two X chromosomes were investigated for males of the sibling species Ellobius talpinus and Ellobius tancrei. Their sex chromosomes, despite their identical G-structure, demonstrate short synaptic fragments and crossover-associated MLH1 foci in both telomeric regions only. The chromatin undergoes modifications in the meiotic sex chromosomes. SUMO-1 marks a small nucleolus-like body of the meiotic XX. ATR and ubiH2A are localized in the asynaptic area and the histone γH2AFX covers the entire XX bivalent. The distribution of some markers of chromatin inactivation differentiates sex chromosomes of mole voles from those of other mammals. Sex chromosomes of both studied species have identical recombination and meiotic inactivation patterns. In Ellobius, similar chromosome morphology masks the functional heteromorphism of the male sex chromosomes, which can be seen at meiosis.

  6. Dicentric chromosomes: unique models to study centromere function and inactivation

    OpenAIRE

    Kaitlin M Stimpson; Matheny, Justyne E.; Sullivan, Beth A.

    2012-01-01

    Dicentric chromosomes are products of genome rearrangement that place two centromeres on the same chromosome. Depending on the organism, dicentric stability varies after formation. In humans, dicentrics occur naturally in a substantial portion of the population and usually segregate successfully in mitosis and meiosis. Their stability has been attributed to inactivation of one of the two centromeres, creating a functionally monocentric chromosome that can segregate normally during cell divisi...

  7. Sex chromosome-specific regulation in the Drosophila male germline but little evidence for chromosomal dosage compensation or meiotic inactivation.

    Science.gov (United States)

    Meiklejohn, Colin D; Landeen, Emily L; Cook, Jodi M; Kingan, Sarah B; Presgraves, Daven C

    2011-08-01

    The evolution of heteromorphic sex chromosomes (e.g., XY in males or ZW in females) has repeatedly elicited the evolution of two kinds of chromosome-specific regulation: dosage compensation--the equalization of X chromosome gene expression in males and females--and meiotic sex chromosome inactivation (MSCI)--the transcriptional silencing and heterochromatinization of the X during meiosis in the male (or Z in the female) germline. How the X chromosome is regulated in the Drosophila melanogaster male germline is unclear. Here we report three new findings concerning gene expression from the X in Drosophila testes. First, X chromosome-wide dosage compensation appears to be absent from most of the Drosophila male germline. Second, microarray analysis provides no evidence for X chromosome-specific inactivation during meiosis. Third, we confirm the previous discovery that the expression of transgene reporters driven by autosomal spermatogenesis-specific promoters is strongly reduced when inserted on the X chromosome versus the autosomes; but we show that this chromosomal difference in expression is established in premeiotic cells and persists in meiotic cells. The magnitude of the X-autosome difference in transgene expression cannot be explained by the absence of dosage compensation, suggesting that a previously unrecognized mechanism limits expression from the X during spermatogenesis in Drosophila. These findings help to resolve several previously conflicting reports and have implications for patterns of genome evolution and speciation in Drosophila.

  8. Sex chromosome-specific regulation in the Drosophila male germline but little evidence for chromosomal dosage compensation or meiotic inactivation.

    Directory of Open Access Journals (Sweden)

    Colin D Meiklejohn

    2011-08-01

    Full Text Available The evolution of heteromorphic sex chromosomes (e.g., XY in males or ZW in females has repeatedly elicited the evolution of two kinds of chromosome-specific regulation: dosage compensation--the equalization of X chromosome gene expression in males and females--and meiotic sex chromosome inactivation (MSCI--the transcriptional silencing and heterochromatinization of the X during meiosis in the male (or Z in the female germline. How the X chromosome is regulated in the Drosophila melanogaster male germline is unclear. Here we report three new findings concerning gene expression from the X in Drosophila testes. First, X chromosome-wide dosage compensation appears to be absent from most of the Drosophila male germline. Second, microarray analysis provides no evidence for X chromosome-specific inactivation during meiosis. Third, we confirm the previous discovery that the expression of transgene reporters driven by autosomal spermatogenesis-specific promoters is strongly reduced when inserted on the X chromosome versus the autosomes; but we show that this chromosomal difference in expression is established in premeiotic cells and persists in meiotic cells. The magnitude of the X-autosome difference in transgene expression cannot be explained by the absence of dosage compensation, suggesting that a previously unrecognized mechanism limits expression from the X during spermatogenesis in Drosophila. These findings help to resolve several previously conflicting reports and have implications for patterns of genome evolution and speciation in Drosophila.

  9. Human male meiotic sex chromosome inactivation

    NARCIS (Netherlands)

    Vries, M. de; Vosters, S.; Merkx, G.F.M.; Hauwers, K.W.M. d'; Wansink, D.G.; Ramos, L.; Boer, P. de

    2012-01-01

    In mammalian male gametogenesis the sex chromosomes are distinctive in both gene activity and epigenetic strategy. At first meiotic prophase the heteromorphic X and Y chromosomes are placed in a separate chromatin domain called the XY body. In this process, X,Y chromatin becomes highly phosphorylate

  10. Dicentric chromosomes: unique models to study centromere function and inactivation.

    Science.gov (United States)

    Stimpson, Kaitlin M; Matheny, Justyne E; Sullivan, Beth A

    2012-07-01

    Dicentric chromosomes are products of genome rearrangement that place two centromeres on the same chromosome. Depending on the organism, dicentric stability varies after formation. In humans, dicentrics occur naturally in a substantial portion of the population and usually segregate successfully in mitosis and meiosis. Their stability has been attributed to inactivation of one of the two centromeres, creating a functionally monocentric chromosome that can segregate normally during cell division. The molecular basis for centromere inactivation is not well understood, although studies in model organisms and in humans suggest that genomic and epigenetic mechanisms can be involved. Furthermore, constitutional dicentric chromosomes ascertained in patients presumably represent the most stable chromosomes, so the spectrum of dicentric fates, if it exists, is not entirely clear. Studies of engineered or induced dicentrics in budding yeast and plants have provided significant insight into the fate of dicentric chromosomes. And, more recently, studies have shown that dicentrics in humans can also undergo multiple fates after formation. Here, we discuss current experimental evidence from various organisms that has deepened our understanding of dicentric behavior and the intriguingly complex process of centromere inactivation.

  11. The mouse X chromosome is enriched for sex-biased genes not subject to selection by meiotic sex chromosome inactivation.

    Science.gov (United States)

    Khil, Pavel P; Smirnova, Natalya A; Romanienko, Peter J; Camerini-Otero, R Daniel

    2004-06-01

    Sex chromosomes are subject to sex-specific selective evolutionary forces. One model predicts that genes with sex-biased expression should be enriched on the X chromosome. In agreement with Rice's hypothesis, spermatogonial genes are over-represented on the X chromosome of mice and sex- and reproduction-related genes are over-represented on the human X chromosome. Male-biased genes are under-represented on the X chromosome in worms and flies, however. Here we show that mouse spermatogenesis genes are relatively under-represented on the X chromosome and female-biased genes are enriched on it. We used Spo11(-/-) mice blocked in spermatogenesis early in meiosis to evaluate the temporal pattern of gene expression in sperm development. Genes expressed before the Spo11 block are enriched on the X chromosome, whereas those expressed later in spermatogenesis are depleted. Inactivation of the X chromosome in male meiosis may be a universal driving force for X-chromosome demasculinization.

  12. Independent clonal origin of multiple uterine leiomyomas that was determined by X chromosome inactivation and microsatellite analysis

    DEFF Research Database (Denmark)

    Canevari, Renata A; Pontes, Anaglória; Rosa, Fabíola E;

    2005-01-01

    OBJECTIVE: In an attempt to clarify the clonality and genetic relationships that are involved in the tumorigenesis of uterine leiomyomas, we used a total of 43 multiple leiomyomas from 14 patients and analyzed the allelic status with 15 microsatellite markers and X chromosome inactivation analysis....... STUDY DESIGN: We have used a set of 15 microsatellite polymorphism markers mapped on 3q, 7p, 11, and 15q by automated analysis. The X chromosome inactivation was evaluated by the methylation status of the X-linked androgen receptor gene. RESULTS: Loss of heterozygosity analysis showed a different...... pattern in 7 of the 8 cases with allelic loss for at least 1 of 15 microsatellite markers that were analyzed. A similar loss of heterozygosity findings at 7p22-15 was detected in 3 samples from the same patient. X chromosome inactivation analysis demonstrated the same inactivated allele in all tumors...

  13. Abnormal X : autosome ratio, but normal X chromosome inactivation in human triploid cultures

    Directory of Open Access Journals (Sweden)

    Norwood Thomas H

    2006-07-01

    Full Text Available Abstract Background X chromosome inactivation (XCI is that aspect of mammalian dosage compensation that brings about equivalence of X-linked gene expression between females and males by inactivating one of the two X chromosomes (Xi in normal female cells, leaving them with a single active X (Xa as in male cells. In cells with more than two X's, but a diploid autosomal complement, all X's but one, Xa, are inactivated. This phenomenon is commonly thought to suggest 1 that normal development requires a ratio of one Xa per diploid autosomal set, and 2 that an early event in XCI is the marking of one X to be active, with remaining X's becoming inactivated by default. Results Triploids provide a test of these ideas because the ratio of one Xa per diploid autosomal set cannot be achieved, yet this abnormal ratio should not necessarily affect the one-Xa choice mechanism for XCI. Previous studies of XCI patterns in murine triploids support the single-Xa model, but human triploids mostly have two-Xa cells, whether they are XXX or XXY. The XCI patterns we observe in fibroblast cultures from different XXX human triploids suggest that the two-Xa pattern of XCI is selected for, and may have resulted from rare segregation errors or Xi reactivation. Conclusion The initial X inactivation pattern in human triploids, therefore, is likely to resemble the pattern that predominates in murine triploids, i.e., a single Xa, with the remaining X's inactive. Furthermore, our studies of XIST RNA accumulation and promoter methylation suggest that the basic features of XCI are normal in triploids despite the abnormal X:autosome ratio.

  14. Nonrandon X chromosome inactivation in B cells from carriers of X chromosome-linked severe combined immunodeficiency

    Energy Technology Data Exchange (ETDEWEB)

    Conley, M.E.; Lavoie, A.; Briggs, C.; Brown, P.; Guerra, C.; Puck, J.M.

    1988-05-01

    X chromosome-linked sever combined immunodeficiency (XSCID) is characterized by markedly reduced numbers of T cells, the absence of proliferative responses to mitogens, and hypogammaglobulinemia but normal or elevated number of B cells. To determine if the failure of the B cells to produce immunoglobulin might be due to expression of the XSCID gene defect in B-lineage cells as well as T cells, the authors analyzed patterns of X chromosome inactivation in B cells from nine obligate carriers of this disorder. A series of somatic cell hybrids that selectively retained the active X chromosome was produced from Epstein-Barr virus-stimulated B cells from each woman. To distinguish between the two X chromosome, the hybrids from each woman were analyzed using an X-linked restriction fragment length polymorphism for which the woman in question was heterozygous. In all obligate carriers of XSCID, the B-cell hybrids demonstrated preferential use of a single X chromosome, the nonmutant X, as the active X. To determine if the small number of B-cell hybrids that contained the mutant X were derived from an immature subset of B cells, lymphocytes from three carriers were separated into surface IgM positive and surface IgM negative B cells prior to exposure to Epstein-Barr virus and production of B-cell hybrids. The results demonstrated normal random X chromosome inactivation in B-cell hybrids derived from the less mature surface IgM positive B cells. These results suggest that the XSCID gene product has a direct effect on B cells as well as T cells and is required during B-cell maturation.

  15. Meiotic sex chromosome inactivation in male mice with targeted disruptions of Xist.

    Science.gov (United States)

    Turner, James M A; Mahadevaiah, Shantha K; Elliott, David J; Garchon, Henri-Jean; Pehrson, John R; Jaenisch, Rudolf; Burgoyne, Paul S

    2002-11-01

    X chromosome inactivation occurs twice during the life cycle of placental mammals. In normal females, one X chromosome in each cell is inactivated early in embryogenesis, while in the male, the X chromosome is inactivated together with the Y chromosome in spermatogenic cells shortly before or during early meiotic prophase. Inactivation of one X chromosome in somatic cells of females serves to equalise X-linked gene dosage between males and females, but the role of male meiotic sex chromosome inactivation (MSCI) is unknown. The inactive X-chromosome of somatic cells and male meiotic cells share similar properties such as late replication and enrichment for histone macroH2A1.2, suggesting a common mechanism of inactivation. This possibility is supported by the fact that Xist RNA that mediates somatic X-inactivation is expressed in the testis of male mice and humans. In the present study we show that both Xist RNA and Tsix RNA, an antisense RNA that controls Xist function in the soma, are expressed in the testis in a germ-cell-dependent manner. However, our finding that MSCI and sex-body formation are unaltered in mice with targeted mutations of Xist that prevent somatic X inactivation suggests that somatic X-inactivation and MSCI occur by fundamentally different mechanisms.

  16. Sex chromosome inactivation in germ cells: emerging roles of DNA damage response pathways

    OpenAIRE

    Ichijima, Yosuke; Sin, Ho-Su; Satoshi H Namekawa

    2012-01-01

    Sex chromosome inactivation in male germ cells is a paradigm of epigenetic programming during sexual reproduction. Recent progress has revealed the underlying mechanisms of sex chromosome inactivation in male meiosis. The trigger of chromosome-wide silencing is activation of the DNA damage response (DDR) pathway, which is centered on the mediator of DNA damage checkpoint 1 (MDC1), a binding partner of phosphorylated histone H2AX (γH2AX). This DDR pathway shares features with the somatic DDR p...

  17. Prognostic value of X-chromosome inactivation in symptomatic female carriers of dystrophinopathy

    Directory of Open Access Journals (Sweden)

    Juan-Mateu Jonàs

    2012-10-01

    Full Text Available Abstract Background Between 8% and 22% of female carriers of DMD mutations exhibit clinical symptoms of variable severity. Development of symptoms in DMD mutation carriers without chromosomal rearrangements has been attributed to skewed X-chromosome inactivation (XCI favouring predominant expression of the DMD mutant allele. However the prognostic use of XCI analysis is controversial. We aimed to evaluate the correlation between X-chromosome inactivation and development of clinical symptoms in a series of symptomatic female carriers of dystrophinopathy. Methods We reviewed the clinical, pathological and genetic features of twenty-four symptomatic carriers covering a wide spectrum of clinical phenotypes. DMD gene analysis was performed using MLPA and whole gene sequencing in blood DNA and muscle cDNA. Blood and muscle DNA was used for X-chromosome inactivation (XCI analysis thought the AR methylation assay in symptomatic carriers and their female relatives, asymptomatic carriers as well as non-carrier females. Results Symptomatic carriers exhibited 49.2% more skewed XCI profiles than asymptomatic carriers. The extent of XCI skewing in blood tended to increase in line with the severity of muscle symptoms. Skewed XCI patterns were found in at least one first-degree female relative in 78.6% of symptomatic carrier families. No mutations altering XCI in the XIST gene promoter were found. Conclusions Skewed XCI is in many cases familial inherited. The extent of XCI skewing is related to phenotype severity. However, the assessment of XCI by means of the AR methylation assay has a poor prognostic value, probably because the methylation status of the AR gene in muscle may not reflect in all cases the methylation status of the DMD gene.

  18. X-chromosomal inactivation directly influences the phenotypic manifestation of X-linked protoporphyria.

    Science.gov (United States)

    Brancaleoni, V; Balwani, M; Granata, F; Graziadei, G; Missineo, P; Fiorentino, V; Fustinoni, S; Cappellini, M D; Naik, H; Desnick, R J; Di Pierro, E

    2016-01-01

    X-linked protoporphyria (XLP), a rare erythropoietic porphyria, results from terminal exon gain-of-function mutations in the ALAS2 gene causing increased ALAS2 activity and markedly increased erythrocyte protoporphyrin levels. Patients present with severe cutaneous photosensitivity and may develop liver dysfunction. XLP was originally reported as X-linked dominant with 100% penetrance in males and females. We characterized 11 heterozygous females from six unrelated XLP families and show markedly varying phenotypic and biochemical heterogeneity, reflecting the degree of X-chromosomal inactivation of the mutant gene. ALAS2 sequencing identified the specific mutation and confirmed heterozygosity among the females. Clinical history, plasma and erythrocyte protoporphyrin levels were determined. Methylation assays of the androgen receptor and zinc-finger MYM type 3 short tandem repeat polymorphisms estimated each heterozygotes X-chromosomal inactivation pattern. Heterozygotes with equal or increased skewing, favoring expression of the wild-type allele had no clinical symptoms and only slightly increased erythrocyte protoporphyrin concentrations and/or frequency of protoporphyrin-containing peripheral blood fluorocytes. When the wild-type allele was preferentially inactivated, heterozygous females manifested the disease phenotype and had both higher erythrocyte protoporphyrin levels and circulating fluorocytes. These findings confirm that the previous dominant classification of XLP is inappropriate and genetically misleading, as the disorder is more appropriately designated XLP.

  19. Loss of DNMT1o disrupts imprinted X chromosome inactivation and accentuates placental defects in females.

    Directory of Open Access Journals (Sweden)

    Serge McGraw

    2013-11-01

    Full Text Available The maintenance of key germline derived DNA methylation patterns during preimplantation development depends on stores of DNA cytosine methyltransferase-1o (DNMT1o provided by the oocyte. Dnmt1o(mat-/- mouse embryos born to Dnmt1(Δ1o/Δ1o female mice lack DNMT1o protein and have disrupted genomic imprinting and associated phenotypic abnormalities. Here, we describe additional female-specific morphological abnormalities and DNA hypomethylation defects outside imprinted loci, restricted to extraembryonic tissue. Compared to male offspring, the placentae of female offspring of Dnmt1(Δ1o/Δ1o mothers displayed a higher incidence of genic and intergenic hypomethylation and more frequent and extreme placental dysmorphology. The majority of the affected loci were concentrated on the X chromosome and associated with aberrant biallelic expression, indicating that imprinted X-inactivation was perturbed. Hypomethylation of a key regulatory region of Xite within the X-inactivation center was present in female blastocysts shortly after the absence of methylation maintenance by DNMT1o at the 8-cell stage. The female preponderance of placental DNA hypomethylation associated with maternal DNMT1o deficiency provides evidence of additional roles beyond the maintenance of genomic imprints for DNA methylation events in the preimplantation embryo, including a role in imprinted X chromosome inactivation.

  20. Sumoylation precedes accumulation of phosphorylated H2AX on sex chromosomes during their meiotic inactivation.

    Science.gov (United States)

    Vigodner, Margarita

    2009-01-01

    During meiosis in male mammals, X and Y chromosomes undergo the process of meiotic sex chromosome inactivation (MSCI). A crucial role in MSCI has recently been reported for BRCA1, ATR kinase, and phosphorylated histone H2AX, but the exact mechanism remains to be determined. Small ubiquitin-like modifier (SUMO) proteins have recently been shown to localize to the sex body in mouse meiotic spermatocytes, but the role they play during MSCI is unknown. In this study, in order to better understand the molecular events of MSCI, we followed dynamic changes in gammaH2AX and SUMO localization patterns during MSCI. Using confocal laser scanning microscopy (CLSM) as an analytical tool for visualizing numerous spermatocytes from the same development stage and for consecutively following the meiotic progression, we were able to demonstrate a very early appearance of SUMO-1, which preceded gammaH2AX accumulation on the sex chromosomes during their meiotic inactivation. In contrast to SUMO-1, SUMO-2/3 was undetectable in zygotene spermatocytes, suggesting a possible specific role for SUMO-1 in the initiation of MSCI.

  1. Chromosome-wide nucleosome replacement and H3.3 incorporation during mammalian meiotic sex chromosome inactivation.

    NARCIS (Netherlands)

    Heijden, G.W. van der; Derijck, A.H.A.; Posfai, E.; Giele, M.M.; Pelczar, P.; Ramos, L.; Wansink, D.G.; Vlag, J. van der; Peters, A.H.; Boer, P. de

    2007-01-01

    In mammalian males, the first meiotic prophase is characterized by formation of a separate chromatin domain called the sex body. In this domain, the X and Y chromosomes are partially synapsed and transcriptionally silenced, a process termed meiotic sex-chromosome inactivation (MSCI). Likewise, unsyn

  2. Centromere inactivation on a neo-Y fusion chromosome in threespine stickleback fish.

    Science.gov (United States)

    Cech, Jennifer N; Peichel, Catherine L

    2016-12-01

    Having one and only one centromere per chromosome is essential for proper chromosome segregation during both mitosis and meiosis. Chromosomes containing two centromeres are known as dicentric and often mis-segregate during cell division, resulting in aneuploidy or chromosome breakage. Dicentric chromosome can be stabilized by centromere inactivation, a process which reestablishes monocentric chromosomes. However, little is known about this process in naturally occurring dicentric chromosomes. Using a combination of fluorescence in situ hybridization (FISH) and immunofluorescence combined with FISH (IF-FISH) on metaphase chromosome spreads, we demonstrate that centromere inactivation has evolved on a neo-Y chromosome fusion in the Japan Sea threespine stickleback fish (Gasterosteus nipponicus). We found that the centromere derived from the ancestral Y chromosome has been inactivated. Our data further suggest that there have been genetic changes to this centromere in the two million years since the formation of the neo-Y chromosome, but it remains unclear whether these genetic changes are a cause or consequence of centromere inactivation.

  3. Enlightening the contribution of the dark matter to the X chromosome inactivation process in mammals.

    Science.gov (United States)

    Casanova, Miguel; Liyakat Ali, Tharvesh Moideen; Rougeulle, Claire

    2016-08-01

    X-chromosome inactivation (XCI) in mammals represents an exceptional example of transcriptional co-regulation occurring at the level of an entire chromosome. XCI is considered as a means to compensate for gene dosage imbalance between sexes, yet the largest part of the chromosome is composed of repeated elements of different nature and origins. Here we consider XCI from a repeat point of view, interrogating the mechanisms for inactivating X chromosome-derived repeated sequences and discussing the contribution of repetitive elements to the silencing process itself and to its evolution.

  4. Nonrandom X chromosome inactivation in natural killer cells from obligate carriers of X-linked severe combined immunodeficiency

    Energy Technology Data Exchange (ETDEWEB)

    Wengler, G.S.; Parolini, O.; Conley, M.E. (Univ. of Tennessee, Memphis (United States) St. Jude Children' s Research Hospital, Memphis, TN (United States)); Allen, R.C. (Baylor College of Medicine, Houston, TX (United States)); Smith, H. (St. Jude Children' s Research Hospital, Memphis, TN (United States))

    1993-01-15

    X-linked severe combined immunodeficiency (XSCID) is characterized by hypogammaglobulinemia, markedly reduced numbers of T cells, absent mitogen responses, decreased numbers of NK cells, and normal or elevated numbers of B cells. The abnormalities in the NK cell and B cell lineages could be attributed to dependence of these cell lineages on T cells or T cell-derived factors, or to expression of the XSCID gene defect in these cell lineages. In past experiments, the authors have examined X chromosome inactivation patterns in T cells and cultured B cells from female obligate carriers of XSCID and have found that both cell lineages demonstrate nonrandom X chromosome inactivation. This indicates that the gene defect is intrinsic to both of these cell lineages. In the present experiments, a polymerase chain reaction technique was used to evaluate X chromosome inactivation patterns in highly purified populations of freshly isolated NK cells, B cells, CD4[sup +] cells, and CD8[sup +] cells from three obligate carriers of XSCID. All four lymphoid cell populations from these three women exhibited exclusive use of a single X as the active X. In contrast, both X chromosomes were used as the active X in neutrophils and monocytes. These findings indicate that the XSCID gene is expressed in the NK cell lineage as well as in T cells and B cells. This observation makes it highly unlikely that the XSCID gene is involved in Ag receptor gene rearrangements. 21 refs., 4 figs.

  5. Random monoallelic expression of genes on autosomes: Parallels with X-chromosome inactivation.

    Science.gov (United States)

    Gendrel, Anne-Valerie; Marion-Poll, Lucile; Katoh, Kimiko; Heard, Edith

    2016-08-01

    Genes are generally expressed from their two alleles, except in some particular cases such as random inactivation of one of the two X chromosomes in female mammals or imprinted genes which are expressed only from the maternal or the paternal allele. A lesser-known phenomenon is random monoallelic expression (RME) of autosomal genes, where genes can be stably expressed in a monoallelic manner, from either one of the parental alleles. Studies on autosomal RME face several challenges. First, RME that is based on epigenetic mechanisms has to be distinguished from biased expression of one allele caused by a DNA sequence polymorphism in a regulatory element. Second, RME should not be confused with transient monoallelic expression often observed in single cell analyses, and that often corresponds to dynamic bursting of expression. Thanks to analyses on clonal cell populations, the existence of RME in cultured cells is now well established. Future studies of RME in vivo will have to overcome tissue heterogeneity and certain technical limitations. Here, we discuss current knowledge on autosomal RME, as well as possible mechanisms controlling these expression patterns and potential implications for development and disease, drawing parallels with what is known for X-chromosome inactivation, a paradigm of random monoallelic expression.

  6. X-chromosomal inactivation directly influences the phenotypic manifestation of X-linked protoporphyria

    Science.gov (United States)

    Brancaleoni, V.; Balwani, M.; Granata, F.; Graziadei, G.; Missineo, P.; Fiorentino, V.; Fustinoni, S.; Cappellini, M.D.; Naik, H.; Desnick, R.J.; Di Pierro, E.

    2015-01-01

    X-linked protoporphyria (XLP), a rare erythropoietic porphyria, results from terminal exon gain-of-function mutations in the ALAS2 gene causing increased ALAS2 activity and markedly increased erythrocyte protoporphyrin levels. Patients present with severe cutaneous photosensitivity and may develop liver dysfunction. XLP was originally reported as X-linked dominant with 100% penetrance in males and females. We characterized 11 heterozygous females from six unrelated XLP families and show markedly varying phenotypic and biochemical heterogeneity, reflecting the degree of X-chromsomal inactivation of the mutant gene. ALAS2 sequencing identified the specific mutation and confirmed heterozygosity among the females. Clinical history, plasma and erythrocyte protoporphyrin levels were determined. Methylation assays of the androgen receptor and zinc-finger MYM type 3 short tandem repeat polymorphisms estimated each heterozygotes X-chromosomal inactivation pattern. Heterozygotes with equal or increased skewing, favoring expression of the wild-type allele had no clinical symptoms and only slightly increased erythrocyte protoporphyrin concentrations and/or frequency of protoporphyrin-containing peripheral blood fluorocytes. When the wild-type allele was preferentially inactivated, heterozygous females manifested the disease phenotype and had both higher erythrocyte protoporphyrin levels and circulating fluorocytes. These findings confirm that the previous dominant classification of XLP is inappropriate and genetically misleading, as the disorder is more appropriately designated XLP. PMID:25615817

  7. A Tth111I RFLP in intron 1 of the mouse Pgk-1 gene allows tracing of X chromosome inactivation

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugan, V.; Saha, B.K. [Emory Univ. School of Medicine, Atlanta, GA (United States)

    1994-09-01

    The X-linked immunodeficiency (xid) in CBA/N mice serves as a model for the X-linked agammaglobulinemia (XLA) syndrome in humans. Like the XLA carriers, the female mice heterozygous for xid (X{sup xid}/X{sup W}) are asymptomatic. The pattern of X chromosome inactivation in the F1 heterozygotes [CBA/N (X{sup xid}/X{sup xid}) X CAST/Ei (X{sup W}/Y)] was investigated by monitoring the methylation status of the two Pgk-1 alleles. Methylation of a CpG dinucleotide in the 5{prime} region of the Pgk-1 gene was previously shown to absolutely correlate with the inactivation of the corresponding X chromosome. In order to distinguish the two alleles, the proximal end of intron 1 of the Pgk-1 gene from CBA/N and CAST/Ei was sequenced. Several nucleotide polymorphisms, including a Tth111I RFLP, were detected in close proximity of the critical CpG dinucleotide. This allowed us to devise an assay based on PCR-amplification of a target DNA encompassing the CpG site as well as the Tth111I site. Results indicate that in circulating B lymphocytes of the female heterozygote only the X-chromosome carrying the normal allele is active (non-random inactivation of the X chromosome) whereas in non-B cells both the X chromosomes are active (random inactivation of the X chromosome). These results were further confirmed by direct measurement of transcription of the two alleles (X{sup xid} and X{sup W}).

  8. Identification of Intellectual Disability Genes in Female Patients with a Skewed X-Inactivation Pattern.

    Science.gov (United States)

    Fieremans, Nathalie; Van Esch, Hilde; Holvoet, Maureen; Van Goethem, Gert; Devriendt, Koenraad; Rosello, Monica; Mayo, Sonia; Martinez, Francisco; Jhangiani, Shalini; Muzny, Donna M; Gibbs, Richard A; Lupski, James R; Vermeesch, Joris R; Marynen, Peter; Froyen, Guy

    2016-08-01

    Intellectual disability (ID) is a heterogeneous disorder with an unknown molecular etiology in many cases. Previously, X-linked ID (XLID) studies focused on males because of the hemizygous state of their X chromosome. Carrier females are generally unaffected because of the presence of a second normal allele, or inactivation of the mutant X chromosome in most of their cells (skewing). However, in female ID patients, we hypothesized that the presence of skewing of X-inactivation would be an indicator for an X chromosomal ID cause. We analyzed the X-inactivation patterns of 288 females with ID, and found that 22 (7.6%) had extreme skewing (>90%), which is significantly higher than observed in the general population (3.6%; P = 0.029). Whole-exome sequencing of 19 females with extreme skewing revealed causal variants in six females in the XLID genes DDX3X, NHS, WDR45, MECP2, and SMC1A. Interestingly, variants in genes escaping X-inactivation presumably cause both XLID and skewing of X-inactivation in three of these patients. Moreover, variants likely accounting for skewing only were detected in MED12, HDAC8, and TAF9B. All tested candidate causative variants were de novo events. Hence, extreme skewing is a good indicator for the presence of X-linked variants in female patients.

  9. XY and ZW: Is Meiotic Sex Chromosome Inactivation the Rule in Evolution?

    OpenAIRE

    Sam Schoenmakers; Evelyne Wassenaar; Hoogerbrugge, Jos W.; Laven, Joop S E; J Anton Grootegoed; Baarends, Willy M.

    2009-01-01

    During meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI) leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW), whereas males have the homogametic ZZ constitution. During chicken oogenesis, the heterologous ZW pair reaches a state of complete heterologous synapsis, and this might enable maintenance of transcription ...

  10. Sex chromosome inactivation in germ cells: emerging roles of DNA damage response pathways.

    Science.gov (United States)

    Ichijima, Yosuke; Sin, Ho-Su; Namekawa, Satoshi H

    2012-08-01

    Sex chromosome inactivation in male germ cells is a paradigm of epigenetic programming during sexual reproduction. Recent progress has revealed the underlying mechanisms of sex chromosome inactivation in male meiosis. The trigger of chromosome-wide silencing is activation of the DNA damage response (DDR) pathway, which is centered on the mediator of DNA damage checkpoint 1 (MDC1), a binding partner of phosphorylated histone H2AX (γH2AX). This DDR pathway shares features with the somatic DDR pathway recognizing DNA replication stress in the S phase. Additionally, it is likely to be distinct from the DDR pathway that recognizes meiosis-specific double-strand breaks. This review article extensively discusses the underlying mechanism of sex chromosome inactivation.

  11. A cross-species comparison of escape from X inactivation in Eutheria: implications for evolution of X chromosome inactivation.

    Science.gov (United States)

    Al Nadaf, Shafagh; Deakin, Janine E; Gilbert, Clément; Robinson, Terence J; Graves, Jennifer A M; Waters, Paul D

    2012-02-01

    Sex chromosome dosage compensation in both eutherian and marsupial mammals is achieved by X chromosome inactivation (XCI)--transcriptional repression that silences one of the two X chromosomes in the somatic cells of females. We recently used RNA fluorescent in situ hybridization (FISH) to show, in individual nuclei, that marsupial X inactivation (in the absence of XIST) occurs on a gene-by-gene basis, and that escape from inactivation is stochastic and independent of gene location. In the absence of similar data from fibroblast cell lines of eutherian representatives, a meaningful comparison is lacking. We therefore used RNA-FISH to examine XCI in fibroblast cell lines obtained from three distantly related eutherian model species: African savannah elephant (Loxodonta africana), mouse (Mus musculus) and human (Homo sapiens). We show that, unlike the orthologous marsupial X, inactivation of the X conserved region (XCR) in eutherians generally is complete. Two-colour RNA-FISH on female human, mouse and elephant interphase nuclei showed that XCR loci have monoallelic expression in almost all nuclei. However, we found that many loci located in the evolutionarily distinct recently added region (XAR) displayed reproducible locus-specific frequencies of nuclei with either one or two active X alleles. We propose that marsupial XCI retains features of an ancient incomplete silencing mechanism that was augmented by the evolution of the XIST gene that progressively stabilized the eutherian XCR. In contrast, the recently added region of the eutherian X displays an incomplete inactivation profile similar to that observed on the evolutionarily distinct marsupial X and the independently evolved monotreme X chromosomes.

  12. Independent evolution of transcriptional inactivation on sex chromosomes in birds and mammals.

    Directory of Open Access Journals (Sweden)

    Alexandra M Livernois

    Full Text Available X chromosome inactivation in eutherian mammals has been thought to be tightly controlled, as expected from a mechanism that compensates for the different dosage of X-borne genes in XX females and XY males. However, many X genes escape inactivation in humans, inactivation of the X in marsupials is partial, and the unrelated sex chromosomes of monotreme mammals have incomplete and gene-specific inactivation of X-linked genes. The bird ZW sex chromosome system represents a third independently evolved amniote sex chromosome system with dosage compensation, albeit partial and gene-specific, via an unknown mechanism (i.e. upregulation of the single Z in females, down regulation of one or both Zs in males, or a combination. We used RNA-fluorescent in situ hybridization (RNA-FISH to demonstrate, on individual fibroblast cells, inactivation of 11 genes on the chicken Z and 28 genes on the X chromosomes of platypus. Each gene displayed a reproducible frequency of 1Z/1X-active and 2Z/2X-active cells in the homogametic sex. Our results indicate that the probability of inactivation is controlled on a gene-by-gene basis (or small domains on the chicken Z and platypus X chromosomes. This regulatory mechanism must have been exapted independently to the non-homologous sex chromosomes in birds and mammals in response to an over-expressed Z or X in the homogametic sex, highlighting the universal importance that (at least partial silencing plays in the evolution on amniote dosage compensation and, therefore, the differentiation of sex chromosomes.

  13. Independent evolution of transcriptional inactivation on sex chromosomes in birds and mammals.

    Science.gov (United States)

    Livernois, Alexandra M; Waters, Shafagh A; Deakin, Janine E; Marshall Graves, Jennifer A; Waters, Paul D

    2013-01-01

    X chromosome inactivation in eutherian mammals has been thought to be tightly controlled, as expected from a mechanism that compensates for the different dosage of X-borne genes in XX females and XY males. However, many X genes escape inactivation in humans, inactivation of the X in marsupials is partial, and the unrelated sex chromosomes of monotreme mammals have incomplete and gene-specific inactivation of X-linked genes. The bird ZW sex chromosome system represents a third independently evolved amniote sex chromosome system with dosage compensation, albeit partial and gene-specific, via an unknown mechanism (i.e. upregulation of the single Z in females, down regulation of one or both Zs in males, or a combination). We used RNA-fluorescent in situ hybridization (RNA-FISH) to demonstrate, on individual fibroblast cells, inactivation of 11 genes on the chicken Z and 28 genes on the X chromosomes of platypus. Each gene displayed a reproducible frequency of 1Z/1X-active and 2Z/2X-active cells in the homogametic sex. Our results indicate that the probability of inactivation is controlled on a gene-by-gene basis (or small domains) on the chicken Z and platypus X chromosomes. This regulatory mechanism must have been exapted independently to the non-homologous sex chromosomes in birds and mammals in response to an over-expressed Z or X in the homogametic sex, highlighting the universal importance that (at least partial) silencing plays in the evolution on amniote dosage compensation and, therefore, the differentiation of sex chromosomes.

  14. High frequency of centromere inactivation resulting in stable dicentric chromosomes of maize.

    Science.gov (United States)

    Han, Fangpu; Lamb, Jonathan C; Birchler, James A

    2006-02-28

    Somatic chromosome spreads from maize (Zea mays L.) plants containing B-A translocation chromosomes undergoing the chromosome type breakage-fusion-bridge cycle were examined by FISH. The size and type of extra chromosomes varied among cells of the same individual. A collection of minichromosomes derived from the chromosome type breakage-fusion-bridge cycle was examined for the presence of stable dicentric chromosomes. Six of 23 chromosomes in the collection contained two regions with DNA sequences typical of centromeres. Functional analysis and immunolabeling of CENH3, the centromere-specific histone H3 variant, revealed only one functional centromere per chromosome, despite the duplicate centromere sequences. One plant was found with an inactive B centromere that had been translocated to the short arm of chromosome 9. The translocated centromere region appeared identical to that of a normal B chromosome. The inactivation of the centromeres was stable for at least four generations. By using dicentrics from dispensable chromosomes, centromere inactivation was found to be quite common under these circumstances.

  15. Dosage compensation of X-chromosome inactivation center-linked genes in porcine preimplantation embryos: Non-chromosome-wide initiation of X-chromosome inactivation in blastocysts.

    Science.gov (United States)

    Hwang, Jae Yeon; Oh, Jong-Nam; Park, Chi-Hun; Lee, Dong-Kyung; Lee, Chang-Kyu

    2015-11-01

    X-chromosome inactivation (XCI) is an epigenetic mechanism that occurs in the eutherian embryo development to equalize the dosage of X-linked genes between males and females. This event is regulated by various factors, and the genes located in the X-chromosome inactivation center (XIC), which is known to be an evolutionary conserved region, are associated with XCI; however, a number of studies regarding this epigenetic event and genomic region are primarily performed in mouse models despite its species-specific features. Thus, in this study, the porcine XIC was identified, and we analyzed the expression of XIC-linked genes in porcine preimplantation embryos. Comparative sequence analysis revealed that the porcine XIC is synteny with that of human and the non-coding RNAs were less conserved compared with the protein coding genes in the XIC. Among the XIC-linked genes, the expression levels of CHIC1 and RLIM were decreased from morula to blastocyst development and their dosage was compensated between the male and female blastocysts. Additionally, the CpG sites of CHIC1 were approximately 50% methylated in parthenote blastocysts. Contrary to these genes, XIST and LOC102165544, an uncharacterized non-coding gene, showed dramatically increased expression levels after the morula stage and preferential female expression in blastocysts. Imprinted XIST expression was not observed, and their CpG sites were hypo-methylated in parthenogenic blastocysts. These results demonstrate that the porcine XIC consists of an evolutionary conserved structure with fewer sequences conserved non-coding RNAs. In addition, a few XIC-linked genes would likely achieve dosage compensation, but XCI would not be completed in porcine blastocysts.

  16. The probability to initiate X chromosome inactivation is determined by the X to autosomal ratio and X chromosome specific allelic properties

    NARCIS (Netherlands)

    K. Monkhorst (Kim); B. de Hoon (Bas); I.H. Jonkers (Iris); E.M. Achame; W. Monkhorst; J.W. Hoogerbrugge (Jos); E. Rentmeester (Eveline); H.V. Westerhoff (Hans); F.G. Grosveld (Frank); J.A. Grootegoed (Anton); J.H. Gribnau (Joost)

    2009-01-01

    textabstractBackground: In female mammalian cells, random X chromosome inactivation (XCI) equalizes the dosage of X-encoded gene products to that in male cells. XCI is a stochastic process, in which each X chromosome has a probability to be inactivated. To obtain more insight in the factors setting

  17. A first-generation X-inactivation profile of the human X chromosome.

    Science.gov (United States)

    Carrel, L; Cottle, A A; Goglin, K C; Willard, H F

    1999-12-01

    In females, most genes on the X chromosome are generally assumed to be transcriptionally silenced on the inactive X as a result of X inactivation. However, particularly in humans, an increasing number of genes are known to "escape" X inactivation and are expressed from both the active (Xa) and inactive (Xi) X chromosomes; such genes reflect different molecular and epigenetic responses to X inactivation and are candidates for phenotypes associated with X aneuploidy. To identify genes that escape X inactivation and to generate a first-generation X-inactivation profile of the X, we have evaluated the expression of 224 X-linked genes and expressed sequence tags by reverse-transcription-PCR analysis of a panel of multiple independent mouse/human somatic cell hybrids containing a normal human Xi but no Xa. The resulting survey yields an initial X-inactivation profile that is estimated to represent approximately 10% of all X-linked transcripts. Of the 224 transcripts tested here, 34 (three of which are pseudoautosomal) were expressed in as many as nine Xi hybrids and thus appear to escape inactivation. The genes that escape inactivation are distributed nonrandomly along the X; 31 of 34 such transcripts map to Xp, implying that the two arms of the X are epigenetically and/or evolutionarily distinct and suggesting that genetic imbalance of Xp may be more severe clinically than imbalance of Xq. A complete X-inactivation profile will provide information relevant to clinical genetics and genetic counseling and should yield insight into the genomic and epigenetic organization of the X chromosome.

  18. Self-assembly and DNA binding of the blocking factor in x chromosome inactivation.

    Directory of Open Access Journals (Sweden)

    Mario Nicodemi

    2007-11-01

    Full Text Available X chromosome inactivation (XCI is the phenomenon occurring in female mammals whereby dosage compensation of X-linked genes is obtained by transcriptional silencing of one of their two X chromosomes, randomly chosen during early embryo development. The earliest steps of random X-inactivation, involving counting of the X chromosomes and choice of the active and inactive X, are still not understood. To explain "counting and choice," the longstanding hypothesis is that a molecular complex, a "blocking factor" (BF, exists. The BF is present in a single copy and can randomly bind to just one X per cell which is protected from inactivation, as the second X is inactivated by default. In such a picture, the missing crucial step is to explain how the molecular complex is self-assembled, why only one is formed, and how it binds only one X. We answer these questions within the framework of a schematic Statistical Physics model, investigated by Monte Carlo computer simulations. We show that a single complex is assembled as a result of a thermodynamic process relying on a phase transition occurring in the system which spontaneously breaks the symmetry between the X's. We discuss, then, the BF interaction with X chromosomes. The thermodynamics of the mechanism that directs the two chromosomes to opposite fates could be, thus, clarified. The insights on the self-assembling and X binding properties of the BF are used to derive a quantitative scenario of biological implications describing current experimental evidences on "counting and choice."

  19. X-chromosome inactivation in Rett Syndrome human induced pluripotent stem cells

    Directory of Open Access Journals (Sweden)

    Aaron YL Cheung

    2012-03-01

    Full Text Available Rett Syndrome (RTT is a neurodevelopmental disorder that affects girls due primarily to heterozygous mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MECP2. Random X-chromosome inactivation (XCI results in cellular mosaicism in which some cells express wild-type MECP2 while other cells express mutant MECP2. The generation of patient-specific human induced Pluripotent Stem cells (hiPSCs facilitates the production of RTT-hiPSC-derived neurons in vitro to investigate disease mechanisms and identify novel drug treatments. The generation of RTT-hiPSCs has been reported by many laboratories, however, the XCI status of RTT-hiPSCs has been inconsistent. Some report RTT-hiPSCs retain the inactive X-chromosome (post-XCI of the founder somatic cell allowing isogenic RTT-hiPSCs that express only the wild-type or mutant MECP2 allele to be isolated from the same patient. Post-XCI RTT-hiPSCs-derived neurons retain this allele-specific expression pattern of wild-type or mutant MECP2. Conversely, others report RTT-hiPSCs in which the inactive X-chromosome of the founder somatic cell reactivates (pre-XCI upon reprogramming into RTT-hiPSCs. Pre-XCI RTT-hiPSC-derived neurons exhibit random XCI resulting in cellular mosaicism with respect to wild-type and mutant MECP2 expression. Here we review and attempt to interpret the inconsistencies in XCI status of RTT-hiPSCs generated to date by comparison to other pluripotent systems in vitro and in vivo and the methods used to analyze XCI. Finally, we discuss the relative strengths and weaknesses of post- and pre-XCI hiPSCs in the context of RTT, and other X-linked and autosomal disorders for translational medicine.

  20. X-inactivation pattern in multiple tissues from two Leber's hereditary optic neuropathy (LHON) patients.

    Science.gov (United States)

    Pegoraro, Elena; Vettori, Andrea; Valentino, Maria L; Molon, Annamaria; Mostacciuolo, Maria L; Howell, Neil; Carelli, Valerio

    2003-05-15

    The more frequent manifestation of ophthalmological abnormalities in males, relative to females, is an unexplained feature of Leber's hereditary optic neuropathy (LHON) that suggests an X-linked modifying gene acting in concert with the pathogenic LHON mitochondrial DNA (mtDNA) mutation. In addition, segregation analysis of the optic neuropathy in LHON pedigrees was compatible with the presence of a recessive-modifying gene on chromosome X. According to this two-locus model, females would be affected only if homozygous or if they were susceptible to skewed X-inactivation. Attempts both to localize the putative LHON-modifying gene by linkage analysis and to find an excess of skewed X-inactivation in affected females were unsuccessful, although the inactivation pattern was only studied in DNA isolated from blood cells. We had the opportunity to analyze a wide range of tissues at autopsy, including the optic nerves and the retina, from two LHON female patients. We found no evidence of skewed X-inactivation in the affected tissues, thus weakening further the hypothesized involvement of a specific X chromosome locus in the pathophysiological expression of LHON.

  1. Loss of Atrx affects trophoblast development and the pattern of X-inactivation in extraembryonic tissues.

    Directory of Open Access Journals (Sweden)

    2006-04-01

    Full Text Available ATRX is an X-encoded member of the SNF2 family of ATPase/helicase proteins thought to regulate gene expression by modifying chromatin at target loci. Mutations in ATRX provided the first example of a human genetic disease associated with defects in such proteins. To better understand the role of ATRX in development and the associated abnormalities in the ATR-X (alpha thalassemia mental retardation, X-linked syndrome, we conditionally inactivated the homolog in mice, Atrx, at the 8- to 16-cell stage of development. The protein, Atrx, was ubiquitously expressed, and male embryos null for Atrx implanted and gastrulated normally but did not survive beyond 9.5 days postcoitus due to a defect in formation of the extraembryonic trophoblast, one of the first terminally differentiated lineages in the developing embryo. Carrier female mice that inherit a maternal null allele should be affected, since the paternal X chromosome is normally inactivated in extraembryonic tissues. Surprisingly, however, some carrier females established a normal placenta and appeared to escape the usual pattern of imprinted X-inactivation in these tissues. Together these findings demonstrate an unexpected, specific, and essential role for Atrx in the development of the murine trophoblast and present an example of escape from imprinted X chromosome inactivation.

  2. Caenorhabditis elegans histone methyltransferase MET-2 shields the male X chromosome from checkpoint machinery and mediates meiotic sex chromosome inactivation.

    Directory of Open Access Journals (Sweden)

    Paula M Checchi

    2011-09-01

    Full Text Available Meiosis is a specialized form of cellular division that results in the precise halving of the genome to produce gametes for sexual reproduction. Checkpoints function during meiosis to detect errors and subsequently to activate a signaling cascade that prevents the formation of aneuploid gametes. Indeed, asynapsis of a homologous chromosome pair elicits a checkpoint response that can in turn trigger germline apoptosis. In a heterogametic germ line, however, sex chromosomes proceed through meiosis with unsynapsed regions and are not recognized by checkpoint machinery. We conducted a directed RNAi screen in Caenorhabditis elegans to identify regulatory factors that prevent recognition of heteromorphic sex chromosomes as unpaired and uncovered a role for the SET domain histone H3 lysine 9 histone methyltransferase (HMTase MET-2 and two additional HMTases in shielding the male X from checkpoint machinery. We found that MET-2 also mediates the transcriptional silencing program of meiotic sex chromosome inactivation (MSCI but not meiotic silencing of unsynapsed chromatin (MSUC, suggesting that these processes are distinct. Further, MSCI and checkpoint shielding can be uncoupled, as double-strand breaks targeted to an unpaired, transcriptionally silenced extra-chromosomal array induce checkpoint activation in germ lines depleted for met-2. In summary, our data uncover a mechanism by which repressive chromatin architecture enables checkpoint proteins to distinguish between the partnerless male X chromosome and asynapsed chromosomes thereby shielding the lone X from inappropriate activation of an apoptotic program.

  3. Caenorhabditis elegans histone methyltransferase MET-2 shields the male X chromosome from checkpoint machinery and mediates meiotic sex chromosome inactivation.

    Science.gov (United States)

    Checchi, Paula M; Engebrecht, JoAnne

    2011-09-01

    Meiosis is a specialized form of cellular division that results in the precise halving of the genome to produce gametes for sexual reproduction. Checkpoints function during meiosis to detect errors and subsequently to activate a signaling cascade that prevents the formation of aneuploid gametes. Indeed, asynapsis of a homologous chromosome pair elicits a checkpoint response that can in turn trigger germline apoptosis. In a heterogametic germ line, however, sex chromosomes proceed through meiosis with unsynapsed regions and are not recognized by checkpoint machinery. We conducted a directed RNAi screen in Caenorhabditis elegans to identify regulatory factors that prevent recognition of heteromorphic sex chromosomes as unpaired and uncovered a role for the SET domain histone H3 lysine 9 histone methyltransferase (HMTase) MET-2 and two additional HMTases in shielding the male X from checkpoint machinery. We found that MET-2 also mediates the transcriptional silencing program of meiotic sex chromosome inactivation (MSCI) but not meiotic silencing of unsynapsed chromatin (MSUC), suggesting that these processes are distinct. Further, MSCI and checkpoint shielding can be uncoupled, as double-strand breaks targeted to an unpaired, transcriptionally silenced extra-chromosomal array induce checkpoint activation in germ lines depleted for met-2. In summary, our data uncover a mechanism by which repressive chromatin architecture enables checkpoint proteins to distinguish between the partnerless male X chromosome and asynapsed chromosomes thereby shielding the lone X from inappropriate activation of an apoptotic program.

  4. Transcriptional changes in response to X chromosome dosage in the mouse: implications for X inactivation and the molecular basis of Turner Syndrome

    Directory of Open Access Journals (Sweden)

    Sargent Carole A

    2010-02-01

    Full Text Available Abstract Background X monosomic mice (39,XO have a remarkably mild phenotype when compared to women with Turner syndrome (45,XO. The generally accepted hypothesis to explain this discrepancy is that the number of genes on the mouse X chromosome which escape X inactivation, and thus are expressed at higher levels in females, is very small. However this hypothesis has never been tested and only a small number of genes have been assayed for their X-inactivation status in the mouse. We performed a global expression analysis in four somatic tissues (brain, liver, kidney and muscle of adult 40,XX and 39,XO mice using the Illumina Mouse WG-6 v1_1 Expression BeadChip and an extensive validation by quantitative real time PCR, in order to identify which genes are expressed from both X chromosomes. Results We identified several genes on the X chromosome which are overexpressed in XX females, including those previously reported as escaping X inactivation, as well as new candidates. However, the results obtained by microarray and qPCR were not fully concordant, illustrating the difficulty in ascertaining modest fold changes, such as those expected for genes escaping X inactivation. Remarkably, considerable variation was observed between tissues, suggesting that inactivation patterns may be tissue-dependent. Our analysis also exposed several autosomal genes involved in mitochondrial metabolism and in protein translation which are differentially expressed between XX and XO mice, revealing secondary transcriptional changes to the alteration in X chromosome dosage. Conclusions Our results support the prediction that the mouse inactive X chromosome is largely silent, while providing a list of the genes potentially escaping X inactivation in rodents. Although the lower expression of X-linked genes in XO mice may not be relevant in the particular tissues/systems which are affected in human X chromosome monosomy, genes deregulated in XO mice are good candidates for

  5. Human Naive Pluripotent Stem Cells Model X Chromosome Dampening and X Inactivation.

    Science.gov (United States)

    Sahakyan, Anna; Kim, Rachel; Chronis, Constantinos; Sabri, Shan; Bonora, Giancarlo; Theunissen, Thorold W; Kuoy, Edward; Langerman, Justin; Clark, Amander T; Jaenisch, Rudolf; Plath, Kathrin

    2017-01-05

    Naive human embryonic stem cells (hESCs) can be derived from primed hESCs or directly from blastocysts, but their X chromosome state has remained unresolved. Here, we show that the inactive X chromosome (Xi) of primed hESCs was reactivated in naive culture conditions. Like cells of the blastocyst, the resulting naive cells contained two active X chromosomes with XIST expression and chromosome-wide transcriptional dampening and initiated XIST-mediated X inactivation upon differentiation. Both establishment of and exit from the naive state (differentiation) happened via an XIST-negative XaXa intermediate. Together, these findings identify a cell culture system for functionally exploring the two X chromosome dosage compensation processes in early human development: X dampening and X inactivation. However, remaining differences between naive hESCs and embryonic cells related to mono-allelic XIST expression and non-random X inactivation highlight the need for further culture improvement. As the naive state resets Xi abnormalities seen in primed hESCs, it may provide cells better suited for downstream applications.

  6. Lack of global meiotic sex chromosome inactivation, and paucity of tissue-specific gene expression on the Drosophila X chromosome

    Directory of Open Access Journals (Sweden)

    Nurminsky Dmitry I

    2011-05-01

    Full Text Available Abstract Background Paucity of male-biased genes on the Drosophila X chromosome is a well-established phenomenon, thought to be specifically linked to the role of these genes in reproduction and/or their expression in the meiotic male germline. In particular, meiotic sex chromosome inactivation (MSCI has been widely considered a driving force behind depletion of spermatocyte-biased X-linked genes in Drosophila by analogy with mammals, even though the existence of global MCSI in Drosophila has not been proven. Results Microarray-based study and qRT-PCR analyses show that the dynamics of gene expression during testis development are very similar between X-linked and autosomal genes, with both showing transcriptional activation concomitant with meiosis. However, the genes showing at least ten-fold expression bias toward testis are significantly underrepresented on the X chromosome. Intriguingly, the genes with similar expression bias toward tissues other than testis, even those not apparently associated with reproduction, are also strongly underrepresented on the X. Bioinformatics analysis shows that while tissue-specific genes often bind silencing-associated factors in embryonic and cultured cells, this trend is less prominent for the X-linked genes. Conclusions Our data show that the global meiotic inactivation of the X chromosome does not occur in Drosophila. Paucity of testis-biased genes on the X appears not to be linked to reproduction or germline-specific events, but rather reflects a general underrepresentation of tissue-biased genes on this chromosome. Our analyses suggest that the activation/repression switch mechanisms that probably orchestrate the highly-biased expression of tissue-specific genes are generally not efficient on the X chromosome. This effect, probably caused by dosage compensation counteracting repression of the X-linked genes, may be the cause of the exodus of highly tissue-biased genes to the autosomes.

  7. Imprinted X chromosome inactivation: evolution of mechanisms in distantly related mammals

    Directory of Open Access Journals (Sweden)

    Shafagh A. Waters

    2015-03-01

    Full Text Available In females, X chromosome inactivation (XCI ensures transcriptional silencing of one of the two Xs (either in a random or imprinted fashion in somatic cells. Comparing this silencing between species has offered insight into different mechanisms of X inactivation, providing clues into the evolution of this epigenetic process in mammals. Long-noncoding RNAs have emerged as a common theme in XCI of therian mammals (eutherian and marsupial. Eutherian X inactivation is regulated by the noncoding RNA product of XIST, within a cis-acting master control region called the X inactivation center (XIC. Marsupials XCI is XIST independent. Instead, XCI is controlled by the long-noncoding RNA Rsx, which appears to be a functional analog of the eutherian XIST gene, insofar that its transcript coats the inactive X and represses activity of genes in cis. In this review we discuss XCI in eutherians, and contrast imprinted X inactivation in mouse and marsupials. We provide particular focus on the evolution of genomic elements that confer the unique epigenetic features that characterize the inactive X chromosome.

  8. Many X-linked microRNAs escape meiotic sex chromosome inactivation.

    Science.gov (United States)

    Song, Rui; Ro, Seungil; Michaels, Jason D; Park, Chanjae; McCarrey, John R; Yan, Wei

    2009-04-01

    Meiotic sex chromosome inactivation (MSCI) during spermatogenesis is characterized by transcriptional silencing of genes on both the X and Y chromosomes in mid-to-late pachytene spermatocytes. MSCI is believed to result from meiotic silencing of unpaired DNA because the X and Y chromosomes remain largely unpaired throughout first meiotic prophase. However, unlike X-chromosome inactivation in female embryonic cells, where 25-30% of X-linked structural genes have been reported to escape inactivation, previous microarray- and RT-PCR-based studies of expression of >364 X-linked mRNA-encoding genes during spermatogenesis have failed to reveal any X-linked gene that escapes the silencing effects of MSCI in primary spermatocytes. Here we show that many X-linked miRNAs are transcribed and processed in pachytene spermatocytes. This unprecedented escape from MSCI by these X-linked miRNAs suggests that they may participate in a critical function at this stage of spermatogenesis, including the possibility that they contribute to the process of MSCI itself, or that they may be essential for post-transcriptional regulation of autosomal mRNAs during the late meiotic and early postmeiotic stages of spermatogenesis.

  9. The evolution of X chromosome inactivation in mammals: the demise of Ohno's hypothesis?

    Science.gov (United States)

    Pessia, Eugénie; Engelstädter, Jan; Marais, Gabriel A B

    2014-04-01

    Ohno's hypothesis states that dosage compensation in mammals evolved in two steps: a twofold hyperactivation of the X chromosome in both sexes to compensate for gene losses on the Y chromosome, and silencing of one X (X-chromosome inactivation, XCI) in females to restore optimal dosage. Recent tests of this hypothesis have returned contradictory results. In this review, we explain this ongoing controversy and argue that a novel view on dosage compensation evolution in mammals is starting to emerge. Ohno's hypothesis may be true for a few, dosage-sensitive genes only. If so few genes are compensated, then why has XCI evolved as a chromosome-wide mechanism? This and several other questions raised by the new data in mammals are discussed, and future research directions are proposed.

  10. X-chromosome inactivation in monkey embryos and pluripotent stem cells.

    Science.gov (United States)

    Tachibana, Masahito; Ma, Hong; Sparman, Michelle L; Lee, Hyo-Sang; Ramsey, Cathy M; Woodward, Joy S; Sritanaudomchai, Hathaitip; Masterson, Keith R; Wolff, Erin E; Jia, Yibing; Mitalipov, Shoukhrat M

    2012-11-15

    Inactivation of one X chromosome in female mammals (XX) compensates for the reduced dosage of X-linked gene expression in males (XY). However, the inner cell mass (ICM) of mouse preimplantation blastocysts and their in vitro counterparts, pluripotent embryonic stem cells (ESCs), initially maintain two active X chromosomes (XaXa). Random X chromosome inactivation (XCI) takes place in the ICM lineage after implantation or upon differentiation of ESCs, resulting in mosaic tissues composed of two cell types carrying either maternal or paternal active X chromosomes. While the status of XCI in human embryos and ICMs remains unknown, majority of human female ESCs show non-random XCI. We demonstrate here that rhesus monkey ESCs also display monoallelic expression and methylation of X-linked genes in agreement with non-random XCI. However, XIST and other X-linked genes were expressed from both chromosomes in isolated female monkey ICMs indicating that ex vivo pluripotent cells retain XaXa. Intriguingly, the trophectoderm (TE) in preimplantation monkey blastocysts also expressed X-linked genes from both alleles suggesting that, unlike the mouse, primate TE lineage does not support imprinted paternal XCI. Our results provide insights into the species-specific nature of XCI in the primate system and reveal fundamental epigenetic differences between in vitro and ex vivo primate pluripotent cells.

  11. Incorporation of 5-ethynyl-2'-deoxyuridine (EdU) as a novel strategy for identification of the skewed X inactivation pattern in balanced and unbalanced X-rearrangements.

    Science.gov (United States)

    Sisdelli, Luiza; Vidi, Angela Cristina; Moysés-Oliveira, Mariana; Di Battista, Adriana; Bortolai, Adriana; Moretti-Ferreira, Danilo; da Silva, Magnus R Dias; Melaragno, Maria Isabel; Carvalheira, Gianna

    2016-02-01

    X-chromosome inactivation occurs randomly in normal female cells. However, the inactivation can be skewed in patients with alterations in X-chromosome. In balanced X-autosome translocations, normal X is preferentially inactivated, while in unbalanced X alterations, the aberrant X is usually inactivated. Here, we present a novel strategy to verify the skewed X inactivation pattern through the incorporation of 5-ethynyl-2'-deoxyuridine (EdU) into cells, in 11 patients: five carriers of balanced X-autosome translocations and six of unbalanced X-chromosome alterations. Since EdU is a labeled nucleoside analog of thymidine, its incorporation during DNA synthesis can reveal late replication regions and the inactive X-chromosome. All EdU findings were validated by the human androgen receptor gene (HUMARA) assay. The late replication regions were easily and quickly visualized in all cells, where inactive Xs are marked with strong green fluorescence. It was observed that the normal X-chromosome was preferentially inactivated in patients with balanced X-autosome translocations; while the aberrant X-chromosome was inactivated in most cells from patients with unbalanced alterations. By performing the fluorescence-based EdU assay, the differences between the active and inactive X-chromosomes are more easily recognizable than by classic cytogenetic methods. Furthermore, EdU incorporation allows the observation of the late replication regions in autosomal segments present in X derivatives from X-autosome translocations. Therefore, EdU assay permits an accurate and efficient cytogenetic evaluation of the X inactivation pattern with a low-cost, easy to perform and highly reproducible technique.

  12. Whole chromosome instability resulting from the synergistic effects of pRB and p53 inactivation.

    Science.gov (United States)

    Manning, A L; Benes, C; Dyson, N J

    2014-05-01

    Whole chromosome instability (CIN) is a common feature of cancer cells and has been linked to increased tumor evolution and metastasis. Several studies have shown that the loss of the pRB tumor suppressor causes mitotic defects and chromosome mis-segregation. pRB is inactivated in many types of cancer and this raises the possibility that the loss of pRB may be a general cause of CIN in tumors. Paradoxically, retinoblastoma tumor cells have a relatively stable karyotype and currently the circumstances in which pRB inactivation causes CIN in human cancers are unclear. Here we utilize a fluorescence in situ hybridization-based approach to score numerical heterogeneity in chromosome copy number as a readout of CIN. Using this technique, we show that high levels of CIN correlate with the combined inactivation of pRB and p53 and that this association is evident in two independent panels of cancer cell lines. Retinoblastoma cell lines characteristically retain a wild-type TP53 gene, providing an opportunity to test the relevance of this functional relationship. We show that retinoblastoma cell lines display mitotic defects similar to those seen when pRB is depleted from non-transformed cells, but that the presence of wild-type p53 suppresses the accumulation of aneuploid cells. A similar synergy between pRB and p53 inactivation was observed in HCT116 cells. These results suggest that the loss of pRB promotes segregation errors, whereas loss of p53 allows tolerance and continued proliferation of the resulting, genomically unstable cancer cells. Hence, it is the cooperative effect of inactivation of both pRB and p53 tumor suppressor pathways that promotes CIN.

  13. X Chromosome Inactivation and Breast Cancer: Epigenetic Alteration in Tumor Initiation and Progression

    Science.gov (United States)

    2007-09-01

    types of mammary tumors, but not others. For instance, X chromosomal abnormalities appear to be associated with basal-like human breast cancer (BLC...andDNA damage-repair pathways to ensure genome integrity (Deng, 2006; Venkitaraman, 2002). In addition, BRCA1 plays a role in meiotic XY inactivation...find- ing that meiotic XY silencing proceeds by a mechanism involving silencing of unsynapsed DNA (Turner et al., 2006), which is distinct from X

  14. Chromosomal gene inactivation in the green sulfur bacterium Chlorobium tepidum by natural transformation

    DEFF Research Database (Denmark)

    Frigaard, N-U; Bryant, D A

    2001-01-01

    Conditions for inactivating chromosomal genes of Chlorobium tepidum by natural transformation and homologous recombination were established. As a model, mutants unable to perform nitrogen fixation were constructed by interrupting nifD with various antibiotic resistance markers. Growth of wild...

  15. X chromosome inactivation and Xist evolution in a rodent lacking LINE-1 activity.

    Science.gov (United States)

    Cantrell, Michael A; Carstens, Bryan C; Wichman, Holly A

    2009-07-15

    Dosage compensation in eutherian mammals occurs by inactivation of one X chromosome in females. Silencing of that X chromosome is initiated by Xist, a large non-coding RNA, whose coating of the chromosome extends in cis from the X inactivation center. LINE-1 (L1) retrotransposons have been implicated as possible players for propagation of the Xist signal, but it has remained unclear whether they are essential components. We previously identified a group of South American rodents in which L1 retrotransposition ceased over 8 million years ago and have now determined that at least one species of these rodents, Oryzomys palustris, still retains X inactivation. We have also isolated and analyzed the majority of the Xist RNA from O. palustris and a sister species retaining L1 activity, Sigmodon hispidus, to determine if evolution in these sequences has left signatures that might suggest a critical role for L1 elements in Xist function. Comparison of rates of Xist evolution in the two species fails to support L1 involvement, although other explanations are possible. Similarly, comparison of known repeats and potential RNA secondary structures reveals no major differences with the exception of a new repeat in O. palustris that has potential to form new secondary structures.

  16. Mammalian X chromosome inactivation evolved as a dosage-compensation mechanism for dosage-sensitive genes on the X chromosome.

    Science.gov (United States)

    Pessia, Eugénie; Makino, Takashi; Bailly-Bechet, Marc; McLysaght, Aoife; Marais, Gabriel A B

    2012-04-03

    How and why female somatic X-chromosome inactivation (XCI) evolved in mammals remains poorly understood. It has been proposed that XCI is a dosage-compensation mechanism that evolved to equalize expression levels of X-linked genes in females (2X) and males (1X), with a prior twofold increase in expression of X-linked genes in both sexes ("Ohno's hypothesis"). Whereas the parity of X chromosome expression between the sexes has been clearly demonstrated, tests for the doubling of expression levels globally along the X chromosome have returned contradictory results. However, changes in gene dosage during sex-chromosome evolution are not expected to impact on all genes equally, and should have greater consequences for dosage-sensitive genes. We show that, for genes encoding components of large protein complexes (≥ 7 members)--a class of genes that is expected to be dosage-sensitive--expression of X-linked genes is similar to that of autosomal genes within the complex. These data support Ohno's hypothesis that XCI acts as a dosage-compensation mechanism, and allow us to refine Ohno's model of XCI evolution. We also explore the contribution of dosage-sensitive genes to X aneuploidy phenotypes in humans, such as Turner (X0) and Klinefelter (XXY) syndromes. X aneuploidy in humans is common and is known to have mild effects because most of the supernumerary X genes are inactivated and not affected by aneuploidy. Only genes escaping XCI experience dosage changes in X-aneuploidy patients. We combined data on dosage sensitivity and XCI to compute a list of candidate genes for X-aneuploidy syndromes.

  17. Detection of skewed X-chromosome inactivation in Fragile X syndrome and X chromosome aneuploidy using quantitative melt analysis.

    Science.gov (United States)

    Godler, David E; Inaba, Yoshimi; Schwartz, Charles E; Bui, Quang M; Shi, Elva Z; Li, Xin; Herlihy, Amy S; Skinner, Cindy; Hagerman, Randi J; Francis, David; Amor, David J; Metcalfe, Sylvia A; Hopper, John L; Slater, Howard R

    2015-07-01

    Methylation of the fragile X mental retardation 1 (FMR1) exon 1/intron 1 boundary positioned fragile X related epigenetic element 2 (FREE2), reveals skewed X-chromosome inactivation (XCI) in fragile X syndrome full mutation (FM: CGG > 200) females. XCI skewing has been also linked to abnormal X-linked gene expression with the broader clinical impact for sex chromosome aneuploidies (SCAs). In this study, 10 FREE2 CpG sites were targeted using methylation specific quantitative melt analysis (MS-QMA), including 3 sites that could not be analysed with previously used EpiTYPER system. The method was applied for detection of skewed XCI in FM females and in different types of SCA. We tested venous blood and saliva DNA collected from 107 controls (CGG chromosome test; (ii) locus-specific XCI skewing towards the hypomethylated state in FM females; and (iii) skewed XCI towards the hypermethylated state in SCA with 3 or more X chromosomes, and in 5% of the 47,XXY individuals. MS-QMA output also showed significant correlation with the EpiTYPER reference method in FM males and females (P < 0.0001) and SCAs (P < 0.05). In conclusion, we demonstrate use of MS-QMA to quantify skewed XCI in two applications with diagnostic utility.

  18. Evidence that meiotic sex chromosome inactivation is essential for male fertility.

    Science.gov (United States)

    Royo, Hélène; Polikiewicz, Grzegorz; Mahadevaiah, Shantha K; Prosser, Haydn; Mitchell, Mike; Bradley, Allan; de Rooij, Dirk G; Burgoyne, Paul S; Turner, James M A

    2010-12-07

    The mammalian X and Y chromosomes share little homology and are largely unsynapsed during normal meiosis. This asynapsis triggers inactivation of X- and Y-linked genes, or meiotic sex chromosome inactivation (MSCI). Whether MSCI is essential for male meiosis is unclear. Pachytene arrest and apoptosis is observed in mouse mutants in which MSCI fails, e.g., Brca1(-/-), H2afx(-/-), Sycp1(-/-), and Msh5(-/-). However, these also harbor defects in synapsis and/or recombination and as such may activate a putative pachytene checkpoint. Here we present evidence that MSCI failure is sufficient to cause pachytene arrest. XYY males exhibit Y-Y synapsis and Y chromosomal escape from MSCI without accompanying synapsis/recombination defects. We find that XYY males, like synapsis/recombination mutants, display pachytene arrest and that this can be circumvented by preventing Y-Y synapsis and associated Y gene expression. Pachytene expression of individual Y genes inserted as transgenes on autosomes shows that expression of the Zfy 1/2 paralogs in XY males is sufficient to phenocopy the pachytene arrest phenotype; insertion of Zfy 1/2 on the X chromosome where they are subject to MSCI prevents this response. Our findings show that MSCI is essential for male meiosis and, as such, provide insight into the differential severity of meiotic mutations' effects on male and female meiosis.

  19. Zfy genes are required for efficient meiotic sex chromosome inactivation (MSCI) in spermatocytes.

    Science.gov (United States)

    Vernet, Nadège; Mahadevaiah, Shantha K; de Rooij, Dirk G; Burgoyne, Paul S; Ellis, Peter J I

    2016-10-13

    During spermatogenesis, germ cells that fail to synapse their chromosomes or fail to undergo meiotic sex chromosome inactivation (MSCI) are eliminated via apoptosis during mid-pachytene. Previous work showed that Y-linked genes Zfy1 and Zfy2 act as 'executioners' for this checkpoint, and that wrongful expression of either gene during pachytene triggers germ cell death. Here, we show that in mice, Zfy genes are also necessary for efficient MSCI and the sex chromosomes are not correctly silenced in Zfy-deficient spermatocytes. This unexpectedly reveals a triple role for Zfy at the mid-pachytene checkpoint in which Zfy genes first promote MSCI, then monitor its progress (since if MSCI is achieved, Zfy genes will be silenced), and finally execute cells with MSCI failure. This potentially constitutes a negative feedback loop governing this critical checkpoint mechanism.

  20. Female chromosome X mosaicism is age-related and preferentially affects the inactivated X chromosome

    Science.gov (United States)

    Machiela, Mitchell J.; Zhou, Weiyin; Karlins, Eric; Sampson, Joshua N.; Freedman, Neal D.; Yang, Qi; Hicks, Belynda; Dagnall, Casey; Hautman, Christopher; Jacobs, Kevin B.; Abnet, Christian C.; Aldrich, Melinda C.; Amos, Christopher; Amundadottir, Laufey T.; Arslan, Alan A.; Beane-Freeman, Laura E.; Berndt, Sonja I.; Black, Amanda; Blot, William J.; Bock, Cathryn H.; Bracci, Paige M.; Brinton, Louise A.; Bueno-de-Mesquita, H Bas; Burdett, Laurie; Buring, Julie E.; Butler, Mary A.; Canzian, Federico; Carreón, Tania; Chaffee, Kari G.; Chang, I-Shou; Chatterjee, Nilanjan; Chen, Chu; Chen, Constance; Chen, Kexin; Chung, Charles C.; Cook, Linda S.; Crous Bou, Marta; Cullen, Michael; Davis, Faith G.; De Vivo, Immaculata; Ding, Ti; Doherty, Jennifer; Duell, Eric J.; Epstein, Caroline G.; Fan, Jin-Hu; Figueroa, Jonine D.; Fraumeni, Joseph F.; Friedenreich, Christine M.; Fuchs, Charles S.; Gallinger, Steven; Gao, Yu-Tang; Gapstur, Susan M.; Garcia-Closas, Montserrat; Gaudet, Mia M.; Gaziano, J. Michael; Giles, Graham G.; Gillanders, Elizabeth M.; Giovannucci, Edward L.; Goldin, Lynn; Goldstein, Alisa M.; Haiman, Christopher A.; Hallmans, Goran; Hankinson, Susan E.; Harris, Curtis C.; Henriksson, Roger; Holly, Elizabeth A.; Hong, Yun-Chul; Hoover, Robert N.; Hsiung, Chao A.; Hu, Nan; Hu, Wei; Hunter, David J.; Hutchinson, Amy; Jenab, Mazda; Johansen, Christoffer; Khaw, Kay-Tee; Kim, Hee Nam; Kim, Yeul Hong; Kim, Young Tae; Klein, Alison P.; Klein, Robert; Koh, Woon-Puay; Kolonel, Laurence N.; Kooperberg, Charles; Kraft, Peter; Krogh, Vittorio; Kurtz, Robert C.; LaCroix, Andrea; Lan, Qing; Landi, Maria Teresa; Marchand, Loic Le; Li, Donghui; Liang, Xiaolin; Liao, Linda M.; Lin, Dongxin; Liu, Jianjun; Lissowska, Jolanta; Lu, Lingeng; Magliocco, Anthony M.; Malats, Nuria; Matsuo, Keitaro; McNeill, Lorna H.; McWilliams, Robert R.; Melin, Beatrice S.; Mirabello, Lisa; Moore, Lee; Olson, Sara H.; Orlow, Irene; Park, Jae Yong; Patiño-Garcia, Ana; Peplonska, Beata; Peters, Ulrike; Petersen, Gloria M.; Pooler, Loreall; Prescott, Jennifer; Prokunina-Olsson, Ludmila; Purdue, Mark P.; Qiao, You-Lin; Rajaraman, Preetha; Real, Francisco X.; Riboli, Elio; Risch, Harvey A.; Rodriguez-Santiago, Benjamin; Ruder, Avima M.; Savage, Sharon A.; Schumacher, Fredrick; Schwartz, Ann G.; Schwartz, Kendra L.; Seow, Adeline; Wendy Setiawan, Veronica; Severi, Gianluca; Shen, Hongbing; Sheng, Xin; Shin, Min-Ho; Shu, Xiao-Ou; Silverman, Debra T.; Spitz, Margaret R.; Stevens, Victoria L.; Stolzenberg-Solomon, Rachael; Stram, Daniel; Tang, Ze-Zhong; Taylor, Philip R.; Teras, Lauren R.; Tobias, Geoffrey S.; Van Den Berg, David; Visvanathan, Kala; Wacholder, Sholom; Wang, Jiu-Cun; Wang, Zhaoming; Wentzensen, Nicolas; Wheeler, William; White, Emily; Wiencke, John K.; Wolpin, Brian M.; Wong, Maria Pik; Wu, Chen; Wu, Tangchun; Wu, Xifeng; Wu, Yi-Long; Wunder, Jay S.; Xia, Lucy; Yang, Hannah P.; Yang, Pan-Chyr; Yu, Kai; Zanetti, Krista A.; Zeleniuch-Jacquotte, Anne; Zheng, Wei; Zhou, Baosen; Ziegler, Regina G.; Perez-Jurado, Luis A.; Caporaso, Neil E.; Rothman, Nathaniel; Tucker, Margaret; Dean, Michael C.; Yeager, Meredith; Chanock, Stephen J.

    2016-01-01

    To investigate large structural clonal mosaicism of chromosome X, we analysed the SNP microarray intensity data of 38,303 women from cancer genome-wide association studies (20,878 cases and 17,425 controls) and detected 124 mosaic X events >2 Mb in 97 (0.25%) women. Here we show rates for X-chromosome mosaicism are four times higher than mean autosomal rates; X mosaic events more often include the entire chromosome and participants with X events more likely harbour autosomal mosaic events. X mosaicism frequency increases with age (0.11% in 50-year olds; 0.45% in 75-year olds), as reported for Y and autosomes. Methylation array analyses of 33 women with X mosaicism indicate events preferentially involve the inactive X chromosome. Our results provide further evidence that the sex chromosomes undergo mosaic events more frequently than autosomes, which could have implications for understanding the underlying mechanisms of mosaic events and their possible contribution to risk for chronic diseases. PMID:27291797

  1. Meiotic recombination, synapsis, meiotic inactivation and sperm aneuploidy in a chromosome 1 inversion carrier.

    Science.gov (United States)

    Kirkpatrick, Gordon; Chow, Victor; Ma, Sai

    2012-01-01

    Disrupted meiotic behaviour of inversion carriers may be responsible for suboptimal sperm parameters in these carriers. This study investigated meiotic recombination, synapsis, transcriptional silencing and chromosome segregation effects in a pericentric inv(1) carrier. Recombination (MLH1), synapsis (SYCP1, SYCP3) and transcriptional inactivation (γH2AX, BRCA1) were examined by fluorescence immunostaining. Chromosome specific rates of recombination were determined by fluorescence in-situ hybridization. Furthermore, testicular sperm was examined for aneuploidy and segregation of the inv(1). Our findings showed that global recombination rates were similar to controls. Recombination on the inv(1) and the sex chromosomes were reduced. The inv(1) associated with the XY body in 43.4% of cells, in which XY recombination was disproportionately absent, and 94.3% of cells displayed asynapsed regions which displayed meiotic silencing regardless of their association with the XY body. Furthermore, a low frequency of chromosomal imbalance was observed in spermatozoa (3.4%). Our results suggest that certain inversion carriers may display unimpaired global recombination and impaired recombination on the involved and the sex chromosomes during meiosis. Asynapsis or inversion-loop formation in the inverted region may be responsible for impaired spermatogenesis and may prevent sperm-chromosome imbalance.

  2. Re-analysis of the larval testis data on meiotic sex chromosome inactivation revealed evidence for tissue-specific gene expression related to the drosophila X chromosome

    Directory of Open Access Journals (Sweden)

    Vibranovski Maria D

    2012-06-01

    Full Text Available Abstract Background Meiotic sex chromosome inactivation (MSCI during spermatogenesis has been proposed as one of the evolutionary driving forces behind both the under-representation of male-biased genes on, and the gene movement out of, the X chromosome in Drosophila. However, the relevance of MSCI in shaping sex chromosome evolution is controversial. Here we examine two aspects of a recent study on testis gene expression (Mikhaylova and Nurminsky, BMC Biol 2011, 9:29 that failed to support the MSCI in Drosophila. First, Mikhaylova and Nurminsky found no differences between X-linked and autosomal genes based on the transcriptional profiling of the early testis development, and thus concluded that MSCI does not occur in D. melanogaster. Second, they also analyzed expression data from several D. melanogaster tissues and concluded that under-representation on the X chromosome is not an exclusive property of testis-biased genes, but instead, a general property of tissue-specific genes. Results By re-analyzing the Mikhaylova and Nurminsky's testis data and the expression data on several D. melanogaster tissues, we made two major findings that refuted their original claims. First, the developmental testis data has generally greater experimental error than conventional analyses, which reduced significantly the power to detect chromosomal differences in expression. Nevertheless, our re-analysis observed significantly lower expression of the X chromosome in the genomic transcriptomes of later development stages of the testis, which is consistent with the MSCI hypothesis. Second, tissue-specific genes are also in general enriched with genes more expressed in testes than in ovaries, that is testis-biased genes. By completely excluding from the analyses the testis-biased genes, which are known to be under-represented in the X, we found that all the other tissue-specific genes are randomly distributed between the X chromosome and the autosomes. Conclusions

  3. Female chromosome X mosaicism is age-related and preferentially affects the inactivated X chromosome

    DEFF Research Database (Denmark)

    Machiela, Mitchell J; Zhou, Weiyin; Karlins, Eric

    2016-01-01

    To investigate large structural clonal mosaicism of chromosome X, we analysed the SNP microarray intensity data of 38,303 women from cancer genome-wide association studies (20,878 cases and 17,425 controls) and detected 124 mosaic X events >2 Mb in 97 (0.25%) women. Here we show rates for X-chrom...

  4. Extensive meiotic asynapsis in mice antagonises meiotic silencing of unsynapsed chromatin and consequently disrupts meiotic sex chromosome inactivation

    OpenAIRE

    Mahadevaiah, Shantha K.; Bourc'his, Déborah; Dirk G de Rooij; Bestor, Timothy H; James M A Turner; Burgoyne, Paul S

    2008-01-01

    Chromosome synapsis during zygotene is a prerequisite for the timely homologous recombinational repair of meiotic DNA double-strand breaks (DSBs). Unrepaired DSBs are thought to trigger apoptosis during midpachytene of male meiosis if synapsis fails. An early pachytene response to asynapsis is meiotic silencing of unsynapsed chromatin (MSUC), which, in normal males, silences the X and Y chromosomes (meiotic sex chromosome inactivation [MSCI]). In this study, we show that MSUC occurs in Spo11-...

  5. No severe and global X chromosome inactivation in meiotic male germline of Drosophila

    Directory of Open Access Journals (Sweden)

    Mikhaylova Lyudmila M

    2012-06-01

    Full Text Available Abstract This article is a response to Vibranovski et al. See correspondence article http://www.biomedcentral.com/1741-7007/10/49 and the original research article http://www.biomedcentral.com/1741-7007/9/29 We have previously reported a high propensity of testis-expressed X-linked genes to activation in meiotic cells, a similarity in global gene expression between the X chromosome and autosomes in meiotic germline, and under-representation of various types of tissue-specific genes on the X chromosome. Based on our findings and a critical review of the current literature, we believe that there is no global and severe silencing of the X chromosome in the meiotic male germline of Drosophila. The term 'meiotic sex chromosome inactivation' (MSCI therefore seems misleading when used to describe the minor underexpression of the X chromosome in the testis of Drosophila, because this term erroneously implies a profound and widespread silencing of the X-linked genes, by analogy to the well-studied MSCI system in mammals, and therefore distracts from identification and analysis of the real mechanisms that orchestrate gene expression and evolution in this species.

  6. Chromosomal patterns in human malignant astrocytomas.

    Science.gov (United States)

    Rey, J A; Bello, M J; de Campos, J M; Kusak, M E; Ramos, C; Benitez, J

    1987-12-01

    Cytogenetic analysis by direct and/or in vitro preparations was performed on 34 malignant astrocytomas. Thirty tumors showed near-diploid chromosome numbers, whereas, tritetraploid chromosome complements were present in four tumors. The most frequent chromosomal changes implied numerical deviations by a gain of chromosomes #7, #19, and #20, and by losses of #10, #22, and Y. Structural rearrangements were present in stem- or side lines of 24 tumors. Although no common chromosomal rearrangement seems to exist among those tumors, chromosomes #1, #6, #7, and #9 were predominantly involved. Polysomy and structural rearrangements of chromosome #7 could be related to the overexpression of epidermal growth factor gene, previously observed in some malignant gliomas.

  7. The Pluripotency Factor-Bound Intron 1 of Xist Is Dispensable for X Chromosome Inactivation and Reactivation In Vitro and In Vivo

    NARCIS (Netherlands)

    A. Minkovsky (Alissa); T.S. Barakat (Tahsin Stefan); N. Sellami (Nadia); M. Chin (Mark Henry); N. Gunhanlar (Nilhan); J.H. Gribnau (Joost); K. Plath (Kathrin)

    2013-01-01

    textabstractX chromosome inactivation (XCI) is a dynamically regulated developmental process with inactivation and reactivation accompanying the loss and gain of pluripotency, respectively. A functional relationship between pluripotency and lack of XCI has been suggested, whereby pluripotency transc

  8. Establishment of X chromosome inactivation and epigenomic features of the inactive X depend on cellular contexts.

    Science.gov (United States)

    Vallot, Céline; Ouimette, Jean-François; Rougeulle, Claire

    2016-09-01

    X chromosome inactivation (XCI) is an essential epigenetic process that ensures X-linked gene dosage equilibrium between sexes in mammals. XCI is dynamically regulated during development in a manner that is intimately linked to differentiation. Numerous studies, which we review here, have explored the dynamics of X inactivation and reactivation in the context of development, differentiation and diseases, and the phenotypic and molecular link between the inactive status, and the cellular context. Here, we also assess whether XCI is a uniform mechanism in mammals by analyzing epigenetic signatures of the inactive X (Xi) in different species and cellular contexts. It appears that the timing of XCI and the epigenetic signature of the inactive X greatly vary between species. Surprisingly, even within a given species, various Xi configurations are found across cellular states. We discuss possible mechanisms underlying these variations, and how they might influence the fate of the Xi.

  9. A History of the Discovery of Random X Chromosome Inactivation in the Human Female and its Significance

    Directory of Open Access Journals (Sweden)

    Sophia Balderman

    2011-07-01

    Full Text Available Genetic determinants of sex in placental mammals developed by the evolution of primordial autosomes into the male and female sex chromosomes. The Y chromosome determines maleness by the action of the gene SRY, which encodes a protein that initiates a sequence of events prompting the embryonic gonads to develop into testes. The X chromosome in the absence of a Y chromosome results in a female by permitting the conversion of the embryonic gonads into ovaries. We trace the historical progress that resulted in the discovery that one X chromosome in the female is randomly inactivated in early embryogenesis, accomplishing approximate equivalency of X chromosome gene dosage in both sexes. This event results in half of the somatic cells in a tissue containing proteins encoded by the genes of the maternal X chromosome and half having proteins encoded by the genes of the paternal X chromosome, on average, accounting for the phenotype of a female heterozygote with an X chromosome mutation. The hypothesis of X chromosome inactivation as a random event early in embryogenesis was first described as a result of studies of variegated coat color in female mice. Similar results were found in women using the X chromosome-linked gene, glucose-6-phosphate dehydrogenase, studied in red cells. The random inactivation of the X chromosome-bearing genes for isoenzyme types A and B of glucose-6-phosphate dehydrogenase was used to establish the clonal origin of neoplasms in informative women with leiomyomas. Behind these discoveries are the stories of the men and women scientists whose research enlightened these aspects of X chromosome function and their implication for medicine.

  10. Exogenous phage recombinase-independent inactivation of chromosomal genes in Yersinia enterocolitica.

    Science.gov (United States)

    Dhar, Mahesh S; Kumar, Pradeep; Virdi, Jugsharan S

    2013-11-01

    Characterization of newly identified genes is necessary to understand their functions. Phenotypic characterization of isogenic mutants provides good understanding of the functions of the genes in wild type strains. In the present study, we report the use of linear dsDNA as a substrate for homologous recombination in Yersinia enterocolitica. A double-stranded linear recombinant DNA (LRD) containing an antibiotic resistance gene flanked by homologous regions to the target gene was created. Transformation of this LRD into Y. enterocolitica led to the replacement of targeted loci with antibiotic resistance gene. Using this strategy, two chromosomal genes namely urease C (ureC) and hemophore A (hasA) were disrupted in three strains of Y. enterocolitica. These recombinations were independent of the EPR functions. This is the first report of EPR-independent inactivation of chromosomal genes in Y. enterocolitica strains.

  11. Chromosome-wide nucleosome replacement and H3.3 incorporation during mammalian meiotic sex chromosome inactivation.

    Science.gov (United States)

    van der Heijden, Godfried W; Derijck, Alwin A H A; Pósfai, Eszter; Giele, Maud; Pelczar, Pawel; Ramos, Liliana; Wansink, Derick G; van der Vlag, Johan; Peters, Antoine H F M; de Boer, Peter

    2007-02-01

    In mammalian males, the first meiotic prophase is characterized by formation of a separate chromatin domain called the sex body. In this domain, the X and Y chromosomes are partially synapsed and transcriptionally silenced, a process termed meiotic sex-chromosome inactivation (MSCI). Likewise, unsynapsed autosomal chromatin present during pachytene is also silenced (meiotic silencing of unsynapsed chromatin, MSUC). Although it is known that MSCI and MSUC are both dependent on histone H2A.X phosphorylation mediated by the kinase ATR, and cause repressive H3 Lys9 dimethylation, the mechanisms underlying silencing are largely unidentified. Here, we demonstrate an extensive replacement of nucleosomes within unsynapsed chromatin, depending on and initiated shortly after induction of MSCI and MSUC. Nucleosomal eviction results in the exclusive incorporation of the H3.3 variant, which to date has primarily been associated with transcriptional activity. Nucleosomal exchange causes loss and subsequent selective reacquisition of specific histone modifications. This process therefore provides a means for epigenetic reprogramming of sex chromatin presumably required for gene silencing in the male mammalian germ line.

  12. Bacillus subtilis chromosome organization oscillates between two distinct patterns

    OpenAIRE

    Wang, Xindan; Montero Llopis, Paula; Rudner, David Z.

    2014-01-01

    In bacteria, faithful and efficient DNA segregation is intimately linked to the spatial organization of the chromosome. Two distinct organization patterns have been described for bacterial chromosomes (ori-ter and left-ori-right) that appear to arise from distinct segregation mechanisms. Here, we show that the Bacillus subtilis chromosome oscillates between them during a replication–segregation cycle. Our data further suggest that the highly conserved condensin complex and the parABS partitio...

  13. Studies of X inactivation and isodisomy in twins provide further evidence that the X chromosomes is not involved in Rett syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Migeon, B.R.; Dunn, M.A.; Schmeckpeper, B.J.; Naidu, S. [Johns Hophins Univ., Baltimore, MD (United States); Thomas, G. [Johns Hopkins Univ., Baltimore, MD (United States)]|[Kennedy-Kreiger Institute, Baltimore, MD (United States)

    1995-03-01

    Rett syndrome (RS), a progressive encephalopathy with onset in infancy, has been attributed to an X-linked mutation, mainly on the basis of its occurrence almost exclusively in females and its concordance in female MZ twins. The underlying mechanisms proposed are an X-linked dominant mutation with male lethality, uniparental disomy of the X chromosome, and/or some disturbance in the process of X inactivation leading to unequal distribution of cells expressing maternal or paternal alleles (referred to as a {open_quotes}nonrandom{close_quotes} or {open_quotes}skewed {close_quotes} inactivation). To determine if the X chromosome is in fact involved in RS, we studied a group of affected females including three pairs of MZ twins, two concordant for RS and one uniquely discordant for RS. Analysis of X-inactivation patterns confirms the frequent nonrandom X inactivation previously observed in MZ twins but indicates that this is independent of RS. Analysis of 29 RS females reveals not one instance of uniparental X disomy, extending the observations previously reported. Therefore, our findings contribute no support for the hypothesis that RS is an X-linked disorder. Furthermore, the concordant phenotype in most MZ females twins with RS, which has not been observed in female twins with known X-linked mutations, argues against an X mutation. 41 refs., 2 figs.

  14. Meiotic sex chromosome inactivation is disrupted in sterile hybrid male house mice.

    Science.gov (United States)

    Campbell, Polly; Good, Jeffrey M; Nachman, Michael W

    2013-03-01

    In male mammals, the X and Y chromosomes are transcriptionally silenced in primary spermatocytes by meiotic sex chromosome inactivation (MSCI) and remain repressed for the duration of spermatogenesis. Here, we test the longstanding hypothesis that disrupted MSCI might contribute to the preferential sterility of heterogametic hybrid males. We studied a cross between wild-derived inbred strains of Mus musculus musculus and M. m. domesticus in which sterility is asymmetric: F1 males with a M. m. musculus mother are sterile or nearly so while F1 males with a M. m. domesticus mother are normal. In previous work, we discovered widespread overexpression of X-linked genes in the testes of sterile but not fertile F1 males. Here, we ask whether this overexpression is specifically a result of disrupted MSCI. To do this, we isolated cells from different stages of spermatogenesis and measured the expression of several genes using quantitative PCR. We found that X overexpression in sterile F1 primary spermatocytes is coincident with the onset of MSCI and persists in postmeiotic spermatids. Using a series of recombinant X genotypes, we then asked whether X overexpression in hybrids is controlled by cis-acting loci across the X chromosome. We found that it is not. Instead, one large interval in the proximal portion of the M. m. musculus X chromosome is associated with both overexpression and the severity of sterility phenotypes in hybrids. These results demonstrate a strong association between X-linked hybrid male sterility and disruption of MSCI and suggest that trans-acting loci on the X are important for the transcriptional regulation of the X chromosome during spermatogenesis.

  15. Silencing of X-Linked MicroRNAs by Meiotic Sex Chromosome Inactivation.

    Directory of Open Access Journals (Sweden)

    Hélène Royo

    2015-10-01

    Full Text Available During the pachytene stage of meiosis in male mammals, the X and Y chromosomes are transcriptionally silenced by Meiotic Sex Chromosome Inactivation (MSCI. MSCI is conserved in therian mammals and is essential for normal male fertility. Transcriptomics approaches have demonstrated that in mice, most or all protein-coding genes on the X chromosome are subject to MSCI. However, it is unclear whether X-linked non-coding RNAs behave in a similar manner. The X chromosome is enriched in microRNA (miRNA genes, with many exhibiting testis-biased expression. Importantly, high expression levels of X-linked miRNAs (X-miRNAs have been reported in pachytene spermatocytes, indicating that these genes may escape MSCI, and perhaps play a role in the XY-silencing process. Here we use RNA FISH to examine X-miRNA expression in the male germ line. We find that, like protein-coding X-genes, X-miRNAs are expressed prior to prophase I and are thereafter silenced during pachynema. X-miRNA silencing does not occur in mouse models with defective MSCI. Furthermore, X-miRNAs are expressed at pachynema when present as autosomally integrated transgenes. Thus, we conclude that silencing of X-miRNAs during pachynema in wild type males is MSCI-dependent. Importantly, misexpression of X-miRNAs during pachynema causes spermatogenic defects. We propose that MSCI represents a chromosomal mechanism by which X-miRNAs, and other potential X-encoded repressors, can be silenced, thereby regulating genes with critical late spermatogenic functions.

  16. Silencing of X-Linked MicroRNAs by Meiotic Sex Chromosome Inactivation.

    Science.gov (United States)

    Royo, Hélène; Seitz, Hervé; ElInati, Elias; Peters, Antoine H F M; Stadler, Michael B; Turner, James M A

    2015-10-01

    During the pachytene stage of meiosis in male mammals, the X and Y chromosomes are transcriptionally silenced by Meiotic Sex Chromosome Inactivation (MSCI). MSCI is conserved in therian mammals and is essential for normal male fertility. Transcriptomics approaches have demonstrated that in mice, most or all protein-coding genes on the X chromosome are subject to MSCI. However, it is unclear whether X-linked non-coding RNAs behave in a similar manner. The X chromosome is enriched in microRNA (miRNA) genes, with many exhibiting testis-biased expression. Importantly, high expression levels of X-linked miRNAs (X-miRNAs) have been reported in pachytene spermatocytes, indicating that these genes may escape MSCI, and perhaps play a role in the XY-silencing process. Here we use RNA FISH to examine X-miRNA expression in the male germ line. We find that, like protein-coding X-genes, X-miRNAs are expressed prior to prophase I and are thereafter silenced during pachynema. X-miRNA silencing does not occur in mouse models with defective MSCI. Furthermore, X-miRNAs are expressed at pachynema when present as autosomally integrated transgenes. Thus, we conclude that silencing of X-miRNAs during pachynema in wild type males is MSCI-dependent. Importantly, misexpression of X-miRNAs during pachynema causes spermatogenic defects. We propose that MSCI represents a chromosomal mechanism by which X-miRNAs, and other potential X-encoded repressors, can be silenced, thereby regulating genes with critical late spermatogenic functions.

  17. Methylation of HpaII and HhaI sites near the polymorphic CAG repeat in the human androgen-receptor gene correlates with X chromosome inactivation

    Energy Technology Data Exchange (ETDEWEB)

    Allen, R.C.; Zoghbi, H.Y.; Moseley, A.B.; Rosenblatt, H.M.; Belmont, J.W. (Baylor College of Medicine, Houston (United States))

    1992-12-01

    The human androgen-receptor gene (HUMARA; GenBank) contains a highly polymorphic trinucleotide repeat in the first exon. The authors have found that the methylation of HpaII and HhaI sites less than 100 pb away from this polymorphic short tandem repeat (STR) correlates with X inactivation. The close proximity of the restriction-enzyme sites to the STR allows the development of a PCR assay that distinguishes between the maternal and paternal alleles and identifies their methylation status. The accuracy of this assay was tested on (a) DNA from hamster/human hybrid cell lines containing either an active or inactive human X chromosome; (b) DNA from normal males and females; and (c) DNA from females showing nonrandom patterns of X inactivation. Data obtained using this assay correlated substantially with those obtained using the PGK, HPRT, and M27[beta] probes, which detect X inactivation patterns by Southern blot analysis. In order to demonstrate one application of this assay, the authors examined X inactivation patterns in the B lymphocytes of potential and obligate carriers of X-linked agammaglobulinemia. 42 refs., 5 figs., 1 tab.

  18. BRCA1, histone H2AX phosphorylation, and male meiotic sex chromosome inactivation.

    Science.gov (United States)

    Turner, James M A; Aprelikova, Olga; Xu, Xiaoling; Wang, Ruihong; Kim, Sangsoo; Chandramouli, Gadisetti V R; Barrett, J Carl; Burgoyne, Paul S; Deng, Chu-Xia

    2004-12-14

    In mammalian spermatogenesis, the X and Y chromosomes are transcriptionally silenced during the pachytene stage of meiotic prophase (meiotic sex chromosome inactivation, MSCI), forming a condensed chromatin domain termed the sex or XY body. The nucleosomal core histone H2AX is phosphorylated within the XY chromatin domain just prior to MSCI, and it has been hypothesized that this triggers the chromatin condensation and transcriptional repression. Here, we show that the kinase ATR localizes to XY chromatin at the onset of MSCI and that this localization is disrupted in mice with a mutant form of the tumor suppressor protein BRCA1. In the mutant pachytene cells, ATR is usually present at nonsex chromosomal sites, where it colocalizes with aberrant sites of H2AX phosphorylation; in these cells, there is MSCI failure. In rare pachytene cells, ATR does locate to XY chromatin, H2AX is then phosphorylated, a sex body forms, and MSCI ensues. These observations highlight an important role for BRCA1 in recruiting the kinase ATR to XY chromatin at the onset of MSCI and provide compelling evidence that it is ATR that phosphorylates H2AX and triggers MSCI.

  19. The probability to initiate X chromosome inactivation is determined by the X to autosomal ratio and X chromosome specific allelic properties.

    Directory of Open Access Journals (Sweden)

    Kim Monkhorst

    Full Text Available In female mammalian cells, random X chromosome inactivation (XCI equalizes the dosage of X-encoded gene products to that in male cells. XCI is a stochastic process, in which each X chromosome has a probability to be inactivated. To obtain more insight in the factors setting up this probability, we studied the role of the X to autosome (X ratio A ratio in initiation of XCI, and have used the experimental data in a computer simulation model to study the cellular population dynamics of XCI.To obtain more insight in the role of the XratioA ratio in initiation of XCI, we generated triploid mouse ES cells by fusion of haploid round spermatids with diploid female and male ES cells. These fusion experiments resulted in only XXY triploid ES cells. XYY and XXX ES lines were absent, suggesting cell death related either to insufficient X-chromosomal gene dosage (XYY or to inheritance of an epigenetically modified X chromosome (XXX. Analysis of active (Xa and inactive (Xi X chromosomes in the obtained triploid XXY lines indicated that the initiation frequency of XCI is low, resulting in a mixed population of XaXiY and XaXaY cells, in which the XaXiY cells have a small proliferative advantage. This result, and findings on XCI in diploid and tetraploid ES cell lines with different X ratio A ratios, provides evidence that the X ratio A ratio determines the probability for a given X chromosome to be inactivated. Furthermore, we found that the kinetics of the XCI process can be simulated using a probability for an X chromosome to be inactivated that is proportional to the X ratio A ratio. These simulation studies re-emphasize our hypothesis that the probability is a function of the concentration of an X-encoded activator of XCI, and of X chromosome specific allelic properties determining the threshold for this activator.The present findings reveal that the probability for an X chromosome to be inactivated is proportional to the X ratio A ratio. This finding

  20. Bacillus subtilis chromosome organization oscillates between two distinct patterns.

    Science.gov (United States)

    Wang, Xindan; Montero Llopis, Paula; Rudner, David Z

    2014-09-02

    Bacterial chromosomes have been found to possess one of two distinct patterns of spatial organization. In the first, called "ori-ter" and exemplified by Caulobacter crescentus, the chromosome arms lie side-by-side, with the replication origin and terminus at opposite cell poles. In the second, observed in slow-growing Escherichia coli ("left-ori-right"), the two chromosome arms reside in separate cell halves, on either side of a centrally located origin. These two patterns, rotated 90° relative to each other, appear to result from different segregation mechanisms. Here, we show that the Bacillus subtilis chromosome alternates between them. For most of the cell cycle, newly replicated origins are maintained at opposite poles with chromosome arms adjacent to each other, in an ori-ter configuration. Shortly after replication initiation, the duplicated origins move as a unit to midcell and the two unreplicated arms resolve into opposite cell halves, generating a left-ori-right pattern. The origins are then actively segregated toward opposite poles, resetting the cycle. Our data suggest that the condensin complex and the parABS partitioning system are the principal driving forces underlying this oscillatory cycle. We propose that the distinct organization patterns observed for bacterial chromosomes reflect a common organization-segregation mechanism, and that simple modifications to it underlie the unique patterns observed in different species.

  1. Single-cell analyses of X Chromosome inactivation dynamics and pluripotency during differentiation

    Science.gov (United States)

    Chen, Geng; Schell, John Paul; Benitez, Julio Aguila; Petropoulos, Sophie; Yilmaz, Marlene; Reinius, Björn; Alekseenko, Zhanna; Shi, Leming; Hedlund, Eva; Lanner, Fredrik; Sandberg, Rickard; Deng, Qiaolin

    2016-01-01

    Pluripotency, differentiation, and X Chromosome inactivation (XCI) are key aspects of embryonic development. However, the underlying relationship and mechanisms among these processes remain unclear. Here, we systematically dissected these features along developmental progression using mouse embryonic stem cells (mESCs) and single-cell RNA sequencing with allelic resolution. We found that mESCs grown in a ground state 2i condition displayed transcriptomic profiles diffused from preimplantation mouse embryonic cells, whereas EpiStem cells closely resembled the post-implantation epiblast. Sex-related gene expression varied greatly across distinct developmental states. We also identified novel markers that were highly enriched in each developmental state. Moreover, we revealed that several novel pathways, including PluriNetWork and Focal Adhesion, were responsible for the delayed progression of female EpiStem cells. Importantly, we “digitalized” XCI progression using allelic expression of active and inactive X Chromosomes and surprisingly found that XCI states exhibited profound variability in each developmental state, including the 2i condition. XCI progression was not tightly synchronized with loss of pluripotency and increase of differentiation at the single-cell level, although these processes were globally correlated. In addition, highly expressed genes, including core pluripotency factors, were in general biallelically expressed. Taken together, our study sheds light on the dynamics of XCI progression and the asynchronicity between pluripotency, differentiation, and XCI. PMID:27486082

  2. A self-enhanced transport mechanism through long noncoding RNAs for X chromosome inactivation.

    Science.gov (United States)

    Li, Chunhe; Hong, Tian; Webb, Chiu-Ho; Karner, Heather; Sun, Sha; Nie, Qing

    2016-08-16

    X-chromosome inactivation (XCI) is the mammalian dosage compensation strategy for balancing sex chromosome content between females and males. While works exist on initiation of symmetric breaking, the underlying allelic choice mechanisms and dynamic regulation responsible for the asymmetric fate determination of XCI remain elusive. Here we combine mathematical modeling and experimental data to examine the mechanism of XCI fate decision by analyzing the signaling regulatory circuit associated with long noncoding RNAs (lncRNAs) involved in XCI. We describe three plausible gene network models that incorporate features of lncRNAs in their localized actions and rapid transcriptional turnovers. In particular, we show experimentally that Jpx (a lncRNA) is transcribed biallelically, escapes XCI, and is asymmetrically dispersed between two X's. Subjecting Jpx to our test of model predictions against previous experimental observations, we identify that a self-enhanced transport feedback mechanism is critical to XCI fate decision. In addition, the analysis indicates that an ultrasensitive response of Jpx signal on CTCF is important in this mechanism. Overall, our combined modeling and experimental data suggest that the self-enhanced transport regulation based on allele-specific nature of lncRNAs and their temporal dynamics provides a robust and novel mechanism for bi-directional fate decisions in critical developmental processes.

  3. Pattern of Chromosomal Aberrations in Patients from North East Iran

    Directory of Open Access Journals (Sweden)

    Saeedeh Ghazaey

    2013-01-01

    Full Text Available Objective: Chromosomal aberrations are common causes of multiple anomaly syndromes. Recurrent chromosomal aberrations have been identified by conventional cytogenetic methods used widely as one of the most important clinical diagnostic techniques.Materials and Methods: In this retrospective study, the incidences of chromosomal aberrations were evaluated in a six year period from 2005 to 2011 in Pardis Clinical and Genetics Laboratory on patients referred to from Mashhad and other cities in Khorasan province. Karyotyping was performed on 3728 patients suspected of having chromosomal abnormalities.Results: The frequencies of the different types of chromosomal abnormalities were determined, and the relative frequencies were calculated in each group. Among these patients, 83.3% had normal karyotypes with no aberrations. The overall incidences of chromosomal abnormalities were 16.7% including sex and autosomal chromosomal anomalies. Of those, 75.1 % showed autosomal chromosomal aberrations. Down syndrome (DS was the most prevalent autosomal aberration in the patients (77.1%. Pericentric inversion of chromosome 9 was seen in 5% of patients. This inversion was prevalent in patients with recurrent spontaneous abortion (RSA. Sex chromosomal aberrations were observed in 24.9% of abnormal patients of which 61% had Turner’s syndrome and 33.5% had Klinefelter’s syndrome.Conclusion: According to the current study, the pattern of chromosomal aberrations in North East of Iran demonstrates the importance of cytogenetic evaluation in patients who show clinical abnormalities. These findings provide a reason for preparing a local cytogenetic data bank to enhance genetic counseling of families who require this service.

  4. Unique sex chromosome systems in Ellobius: How do male XX chromosomes recombine and undergo pachytene chromatin inactivation?

    OpenAIRE

    Sergey Matveevsky; Irina Bakloushinskaya; Oxana Kolomiets

    2016-01-01

    Most mammalian species have heteromorphic sex chromosomes in males, except for a few enigmatic groups such as the mole voles Ellobius, which do not have the Y chromosome and Sry gene. The Ellobius (XX ♀♂ ) system of sex chromosomes has no analogues among other animals. The structure and meiotic behaviour of the two X chromosomes were investigated for males of the sibling species Ellobius talpinus and Ellobius tancrei. Their sex chromosomes, despite their identical G-structure, demonstrate sho...

  5. De novo interstitial direct duplication of Xq21.1q25 associated with skewed X-inactivation pattern.

    Science.gov (United States)

    Tachdjian, G; Aboura, A; Benkhalifa, M; Creveaux, I; Foix-Hélias, L; Gadisseux, J F; Boespflug-Tanguy, O; Mohammed, M; Labrune, P

    2004-12-15

    Genotype-phenotype correlation in women with an abnormal phenotype associated with a duplication of the long arm of the X chromosome remains unclear. We report on prenatal diagnosis and follow-up of a girl with an Xq duplication and dysmorphic features. The abnormal phenotype included growth retardation, hypotonia, and nystagmus. In order to improve the resolution of the cytogenetic analysis, we used both conventional and array-based comparative genomic hybridization to perform a global molecular cytogenetic analysis of the genome. These molecular cytogenetic analyses showed a direct duplication Xq21.1 --> q25 without other chromosomal abnormalities. This duplication was originating from the paternal X chromosome. Moreover, a skewed X-inactivation pattern was observed leading to a partial functional disomy of the chromosomal region Xq21.1q25. This report and review of the literature suggest that functional disomy for chromosome X could explain the abnormal phenotype. In prenatal diagnosis, this can have implication for patient management and genetic counseling.

  6. Nuclear mRNA degradation pathway(s are implicated in Xist regulation and X chromosome inactivation.

    Directory of Open Access Journals (Sweden)

    Constance Ciaudo

    2006-06-01

    Full Text Available A critical step in X-chromosome inactivation (XCI, which results in the dosage compensation of X-linked gene expression in mammals, is the coating of the presumptive inactive X chromosome by the large noncoding Xist RNA, which then leads to the recruitment of other factors essential for the heterochromatinisation of the inactive X and its transcriptional silencing. In an approach aimed at identifying genes implicated in the X-inactivation process by comparative transcriptional profiling of female and male mouse gastrula, we identified the Eif1 gene involved in translation initiation and RNA degradation. We show here that female embryonic stem cell lines, silenced by RNA interference for the Eif1 gene, are unable to form Xist RNA domains upon differentiation and fail to undergo X-inactivation. To probe further an effect involving RNA degradation pathways, the inhibition by RNA interference of Rent1, a factor essential for nonsense-mediated decay and Exosc10, a specific nuclear component of the exosome, was analysed and shown to similarly impair Xist upregulation and XCI. In Eif1-, Rent1-, and Exosc10-interfered clones, Xist spliced form(s are strongly downregulated, while the levels of unspliced form(s of Xist and the stability of Xist RNA remain comparable to that of the control cell lines. Our data suggests a role for mRNA nuclear degradation pathways in the critical regulation of spliced Xist mRNA levels and the onset of the X-inactivation process.

  7. X chromosome-linked and mitochondrial gene control of Leber hereditary optic neuropathy: Evidence from segregation analysis for dependence on X chromosome inactivation

    Energy Technology Data Exchange (ETDEWEB)

    Xiangdong Bu; Rotter, J.I. (Cedars-Sinai Medical Center, Los Angeles, CA (United States) Univ. of California, Los Angeles (United States))

    1991-09-15

    Leber hereditary optic neuropathy (LHON) has been shown to involve mutation(s) of mitochondrial DNA, yet there remain several confusing aspects of its inheritance not explained by mitochondrial inheritance alone, including male predominance, reduced penetrance, and a later age of onset in females. By extending segregation analysis methods to disorders that involve both a mitochondrial and a nuclear gene locus, the authors show that the available pedigree data for LHON are most consistent with a two-locus disorder, with one responsible gene being mitochondrial and the other nuclear and X chromosome-linked. Furthermore, they have been able to extend the two-locus analytic method and demonstrate that a proportion of affected females are likely heterozygous at the X chromosome-linked locus and are affected due to unfortunate X chromosome inactivation, thus providing an explanation for the later age of onset in females. The estimated penetrance for a heterozygous female is 0.11{plus minus}0.02. The calculated frequency of the X chromosome-linked gene for LHON is 0.l08. Among affected females, 60% are expected to be heterozygous, and the remainder are expected to be homozygous at the responsible X chromosome-linked locus.

  8. Escape of X-linked miRNA genes from meiotic sex chromosome inactivation.

    Science.gov (United States)

    Sosa, Enrique; Flores, Luis; Yan, Wei; McCarrey, John R

    2015-11-01

    Past studies have indicated that transcription of all X-linked genes is repressed by meiotic sex chromosome inactivation (MSCI) during the meiotic phase of spermatogenesis in mammals. However, more recent studies have shown an increase in steady-state levels of certain X-linked miRNAs in pachytene spermatocytes, suggesting that either synthesis of these miRNAs increases or that degradation of these miRNAs decreases dramatically in these cells. To distinguish between these possibilities, we performed RNA-FISH to detect nascent transcripts from multiple miRNA genes in various spermatogenic cell types. Our results show definitively that Type I X-linked miRNA genes are subject to MSCI, as are all or most X-linked mRNA genes, whereas Type II and III X-linked miRNA genes escape MSCI by continuing ongoing, active transcription in primary spermatocytes. We corroborated these results by co-localization of RNA-FISH signals with both a corresponding DNA-FISH signal and an immunofluorescence signal for RNA polymerase II. We also found that X-linked miRNA genes that escape MSCI locate non-randomly to the periphery of the XY body, whereas genes that are subject to MSCI remain located within the XY body in pachytene spermatocytes, suggesting that the mechanism of escape of X-linked miRNA genes from MSCI involves their relocation to a position outside of the repressive chromatin domain associated with the XY body. The fact that Type II and III X-linked miRNA genes escape MSCI suggests an immediacy of function of the encoded miRNAs specifically required during the meiotic stages of spermatogenesis.

  9. Variations of X chromosome inactivation occur in early passages of female human embryonic stem cells.

    Directory of Open Access Journals (Sweden)

    Tamar Dvash

    Full Text Available X chromosome inactivation (XCI is a dosage compensation mechanism essential for embryonic development and cell physiology. Human embryonic stem cells (hESCs derived from inner cell mass (ICM of blastocyst stage embryos have been used as a model system to understand XCI initiation and maintenance. Previous studies of undifferentiated female hESCs at intermediate passages have shown three possible states of XCI; 1 cells in a pre-XCI state, 2 cells that already exhibit XCI, or 3 cells that never undergo XCI even upon differentiation. In this study, XCI status was assayed in ten female hESC lines between passage 5 and 15 to determine whether XCI variations occur in early passages of hESCs. Our results show that three different states of XCI already exist in the early passages of hESC. In addition, we observe one cell line with skewed XCI and preferential expression of X-linked genes from the paternal allele, while another cell line exhibits random XCI. Skewed XCI in undifferentiated hESCs may be due to clonal selection in culture instead of non-random XCI in ICM cells. We also found that XIST promoter methylation is correlated with silencing of XIST transcripts in early passages of hESCs, even in the pre-XCI state. In conclusion, XCI variations already take place in early passages of hESCs, which may be a consequence of in vitro culture selection during the derivation process. Nevertheless, we cannot rule out the possibility that XCI variations in hESCs may reflect heterogeneous XCI states in ICM cells that stochastically give rise to hESCs.

  10. Chromosome driven spatial patterning of proteins in bacteria.

    Directory of Open Access Journals (Sweden)

    Saeed Saberi

    Full Text Available The spatial patterning of proteins in bacteria plays an important role in many processes, from cell division to chemotaxis. In the asymmetrically dividing bacteria Caulobacter crescentus, a scaffolding protein, PopZ, localizes to both poles and aids the differential patterning of proteins between mother and daughter cells during division. Polar patterning of misfolded proteins in Escherichia coli has also been shown, and likely plays an important role in cellular ageing. Recent experiments on both of the above systems suggest that the presence of chromosome free regions along with protein multimerization may be a mechanism for driving the polar localization of proteins. We have developed a simple physical model for protein localization using only these two driving mechanisms. Our model reproduces all the observed patterns of PopZ and misfolded protein localization--from diffuse, unipolar, and bipolar patterns and can also account for the observed patterns in a variety of mutants. The model also suggests new experiments to further test the role of the chromosome in driving protein patterning, and whether such a mechanism is responsible for helping to drive the differentiation of the cell poles.

  11. Caenorhabditis elegans histone methyltransferase MET-2 shields the male X chromosome from checkpoint machinery and mediates meiotic sex chromosome inactivation.

    OpenAIRE

    Checchi, Paula M.; JoAnne Engebrecht

    2011-01-01

    Meiosis is a specialized form of cellular division that results in the precise halving of the genome to produce gametes for sexual reproduction. Checkpoints function during meiosis to detect errors and subsequently to activate a signaling cascade that prevents the formation of aneuploid gametes. Indeed, asynapsis of a homologous chromosome pair elicits a checkpoint response that can in turn trigger germline apoptosis. In a heterogametic germ line, however, sex chromosomes proceed through meio...

  12. Extensive meiotic asynapsis in mice antagonises meiotic silencing of unsynapsed chromatin and consequently disrupts meiotic sex chromosome inactivation.

    Science.gov (United States)

    Mahadevaiah, Shantha K; Bourc'his, Déborah; de Rooij, Dirk G; Bestor, Timothy H; Turner, James M A; Burgoyne, Paul S

    2008-07-28

    Chromosome synapsis during zygotene is a prerequisite for the timely homologous recombinational repair of meiotic DNA double-strand breaks (DSBs). Unrepaired DSBs are thought to trigger apoptosis during midpachytene of male meiosis if synapsis fails. An early pachytene response to asynapsis is meiotic silencing of unsynapsed chromatin (MSUC), which, in normal males, silences the X and Y chromosomes (meiotic sex chromosome inactivation [MSCI]). In this study, we show that MSUC occurs in Spo11-null mouse spermatocytes with extensive asynapsis but lacking meiotic DSBs. In contrast, three mutants (Dnmt3l, Msh5, and Dmc1) with high levels of asynapsis and numerous persistent unrepaired DSBs have a severely impaired MSUC response. We suggest that MSUC-related proteins, including the MSUC initiator BRCA1, are sequestered at unrepaired DSBs. All four mutants fail to silence the X and Y chromosomes (MSCI failure), which is sufficient to explain the midpachytene apoptosis. Apoptosis does not occur in mice with a single additional asynapsed chromosome with unrepaired meiotic DSBs and no disturbance of MSCI.

  13. Inactivation or non-reactivation: what accounts better for the silence of sex chromosomes during mammalian male meiosis?

    Science.gov (United States)

    Page, Jesús; de la Fuente, Roberto; Manterola, Marcia; Parra, María Teresa; Viera, Alberto; Berríos, Soledad; Fernández-Donoso, Raúl; Rufas, Julio S

    2012-06-01

    During the first meiotic prophase in male mammals, sex chromosomes undergo a program of transcriptional silencing called meiotic sex chromosome inactivation (MSCI). MSCI is triggered by accumulation of proteins like BRCA1, ATR, and γH2AX on unsynapsed chromosomes, followed by local changes on the sex chromatin, including histone modifications, incorporation of specific histone variants, non-histone proteins, and RNAs. It is generally thought that MSCI represents the transition of unsynapsed chromatin from a transcriptionally active state to a repressed state. However, transcription is generally low in the whole nucleus during the early stages of the first meiotic prophase, when markers of MSCI first appear, and is then reactivated globally during pachytene. Thus, an alternative possibility is that MSCI represents the targeted maintenance and/or reinforcement of a prior repressed state, i.e., a failure to reactivate. Here, we present an analysis of the temporal and spatial appearance of transcriptional and MSCI markers, as well as chromatin modifications related to transcriptional regulation. We show that levels of RNA pol II and histone H3 acetylated at lysine 9 (H3K9ac) are low during leptotene, zygotene, and early pachytene, but increase strongly in mid-pachytene, indicating that reactivation occurs with some delay after synapsis. However, while transcription markers appear abundantly on the autosomes at mid-pachytene, they are not directed to the sex chromosomes. Interestingly, we found that chromatin modifications related to transcriptional silencing and/or MSCI, namely, histone H3 trimethylated at lysine 9 (H3K9me3), histone H3 monomethylated at lysine 4 (H3K4me1), γH2AX, SUMO1, and XMR, appear on the sex chromosomes before autosomes become reactivated. These results suggest that the onset of MSCI during late zygotene and early pachytene may prevent sex chromosome reactivation during mid-pachytene instead of promoting inactivation de novo. Additionally, we

  14. Pachytene asynapsis drives meiotic sex chromosome inactivation and leads to substantial postmeiotic repression in spermatids.

    Science.gov (United States)

    Turner, James M A; Mahadevaiah, Shantha K; Ellis, Peter J I; Mitchell, Michael J; Burgoyne, Paul S

    2006-04-01

    Transcriptional silencing of the sex chromosomes during male meiosis (MSCI) is conserved among organisms with limited sex chromosome synapsis, including mammals. Since the 1990s the prevailing view has been that MSCI in mammals is transient, with sex chromosome reactivation occurring as cells exit meiosis. Recently, we found that any chromosome region unsynapsed during pachytene of male and female mouse meiosis is subject to transcriptional silencing (MSUC), and we hypothesized that MSCI is an inevitable consequence of this more general meiotic silencing mechanism. Here, we provide direct evidence that asynapsis does indeed drive MSCI. We also show that a substantial degree of transcriptional repression of the sex chromosomes is retained postmeiotically, and we provide evidence that this postmeiotic repression is a downstream consequence of MSCI/MSUC. While this postmeiotic repression occurs after the loss of MSUC-related proteins at the end of prophase, other histone modifications associated with transcriptional repression have by then become established.

  15. Characterization of X chromosome inactivation using integrated analysis of whole-exome and mRNA sequencing.

    Directory of Open Access Journals (Sweden)

    Szabolcs Szelinger

    Full Text Available In females, X chromosome inactivation (XCI is an epigenetic, gene dosage compensatory mechanism by inactivation of one copy of X in cells. Random XCI of one of the parental chromosomes results in an approximately equal proportion of cells expressing alleles from either the maternally or paternally inherited active X, and is defined by the XCI ratio. Skewed XCI ratio is suggestive of non-random inactivation, which can play an important role in X-linked genetic conditions. Current methods rely on indirect, semi-quantitative DNA methylation-based assay to estimate XCI ratio. Here we report a direct approach to estimate XCI ratio by integrated, family-trio based whole-exome and mRNA sequencing using phase-by-transmission of alleles coupled with allele-specific expression analysis. We applied this method to in silico data and to a clinical patient with mild cognitive impairment but no clear diagnosis or understanding molecular mechanism underlying the phenotype. Simulation showed that phased and unphased heterozygous allele expression can be used to estimate XCI ratio. Segregation analysis of the patient's exome uncovered a de novo, interstitial, 1.7 Mb deletion on Xp22.31 that originated on the paternally inherited X and previously been associated with heterogeneous, neurological phenotype. Phased, allelic expression data suggested an 83∶20 moderately skewed XCI that favored the expression of the maternally inherited, cytogenetically normal X and suggested that the deleterious affect of the de novo event on the paternal copy may be offset by skewed XCI that favors expression of the wild-type X. This study shows the utility of integrated sequencing approach in XCI ratio estimation.

  16. Genome organization and DNA methylation patterns of B chromosomes in the red fox and Chinese raccoon dogs.

    Science.gov (United States)

    Bugno-Poniewierska, Monika; Solek, Przemysław; Wronski, Mariusz; Potocki, Leszek; Jezewska-Witkowska, Grażyna; Wnuk, Maciej

    2014-12-01

    The molecular structure of B chromosomes (Bs) is relatively well studied. Previous research demonstrates that Bs of various species usually contain two types of repetitive DNA sequences, satellite DNA and ribosomal DNA, but Bs also contain genes encoding histone proteins and many others. However, many questions remain regarding the origin and function of these chromosomes. Here, we focused on the comparative cytogenetic characteristics of the red fox and Chinese raccoon dog B chromosomes with particular attention to the distribution of repetitive DNA sequences and their methylation status. We confirmed that the small Bs of the red fox show a typical fluorescent telomeric distal signal, whereas medium-sized Bs of the Chinese raccoon dog were characterized by clusters of telomeric sequences along their length. We also found different DNA methylation patterns for the B chromosomes of both species. Therefore, we concluded that DNA methylation may maintain the transcriptional inactivation of DNA sequences localized to B chromosomes and may prevent genetic unbalancing and several negative phenotypic effects.

  17. Inactivation of ATM/ATR DNA damage checkpoint promotes androgen induced chromosomal instability in prostate epithelial cells.

    Directory of Open Access Journals (Sweden)

    Yung-Tuen Chiu

    Full Text Available The ATM/ATR DNA damage checkpoint functions in the maintenance of genetic stability and some missense variants of the ATM gene have been shown to confer a moderate increased risk of prostate cancer. However, whether inactivation of this checkpoint contributes directly to prostate specific cancer predisposition is still unknown. Here, we show that exposure of non-malignant prostate epithelial cells (HPr-1AR to androgen led to activation of the ATM/ATR DNA damage response and induction of cellular senescence. Notably, knockdown of the ATM gene expression in HPr-1AR cells can promote androgen-induced TMPRSS2: ERG rearrangement, a prostate-specific chromosome translocation frequently found in prostate cancer cells. Intriguingly, unlike the non-malignant prostate epithelial cells, the ATM/ATR DNA damage checkpoint appears to be defective in prostate cancer cells, since androgen treatment only induced a partial activation of the DNA damage response. This mechanism appears to preserve androgen induced autophosphorylation of ATM and phosphorylation of H2AX, lesion processing and repair pathway yet restrain ATM/CHK1/CHK2 and p53 signaling pathway. Our findings demonstrate that ATM/ATR inactivation is a crucial step in promoting androgen-induced genomic instability and prostate carcinogenesis.

  18. A novel Tth111I restriction fragment length polymorphism (RFLP) allows tracing of X-chromosome inactivation in the (Xid) hetrozygote

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, V.; Sell, W.; Saha, B.K. [Emory Univ. of School of Medicine, Atlanta, GA (United States)] [and others

    1996-02-01

    The X-linked immunodeficiency (Xid) in CBA/N mice serves as a model for the X-linked agammaglobulinemia (XLA) syndrome in man. X-chromosome inactivation in F{sub 1} heterozygotes derived from CBA/N (X{sup xid}/X{sup xid}) and B6.Pgk-1a (X{sup +}/Y) was investigated by monitoring the methylation status of the individual Pgk-1 alleles, Pgk-1b and Pgk-1a, respectively, using a novel Tth111I RFLP. Results indicate that in circulating B lymphocytes of female heterozygotes, only the X chromosomes carrying the normal alleles (X{sup +}) are active (nonrandom inactivation of the X chromosome), whereas in non-B cells both the X chromosomes (X{sup +} and X{sup xid}) are active (random inactivation of the X chromosome). These results were further confirmed by direct evaluation of transcription of the Btk gene, the gene mutated both in Xid and in XLA. 36 refs., 2 figs., 2 tabs.

  19. Living with two X chromosomes: of mice and women : studies on the initiation mechanisms of X chromosome inactivation in stem cells and mouse models, and the role of RNF12 herein

    NARCIS (Netherlands)

    T.S. Barakat (Tahsin Stefan)

    2012-01-01

    markdownabstract__Abstract__ In this thesis work, we have investigated mechanisms involved in regulation of the initiation of X chromosome inactivation (XCI). Starting point was our earlier hypothesis that the initiation of XCI is a stochastic process, controlled in trans by autosomally-encoded XCI

  20. Skewed X-chromosome inactivation in female carriers of dyskeratosis congenita

    Energy Technology Data Exchange (ETDEWEB)

    Devriendt, K.; Matthijs, G.; Legius, E. [Univ. Hospital Gasthuisberg, Leuven (Belgium)] [and others

    1997-03-01

    In this study, we report on a family with X-linked dyskeratosis congenita (DC). Linkage analysis with markers in the factor VIII gene at Xq28 yielded a LOD score of 2 at a recombination of 0. Clinical manifestations of DC, such as skin lesions following the Blaschko lines, were present in two obligate carrier females. Highly skewed X inactivation was observed in white blood cells, cultured skin fibroblasts, and buccal mucosa from female carriers of DC in this family. This suggests a critical role for the DC gene in bone marrow-cell and fibroblast-cell proliferation. 23 refs., 4 figs., 1 tab.

  1. Error-prone ZW pairing and no evidence for meiotic sex chromosome inactivation in the chicken germ line.

    Science.gov (United States)

    Guioli, Silvana; Lovell-Badge, Robin; Turner, James M A

    2012-01-01

    In the male mouse the X and Y chromosomes pair and recombine within the small pseudoautosomal region. Genes located on the unsynapsed segments of the X and Y are transcriptionally silenced at pachytene by Meiotic Sex Chromosome Inactivation (MSCI). The degree to which MSCI is conserved in other vertebrates is currently unclear. In the female chicken the ZW bivalent is thought to undergo a transient phase of full synapsis at pachytene, starting from the homologous ends and spreading through the heterologous regions. It has been proposed that the repair of the ZW DNA double-strand breaks (DSBs) is postponed until diplotene and that the ZW bivalent is subject to MSCI, which is independent of its synaptic status. Here we present a distinct model of meiotic pairing and silencing of the ZW pair during chicken oogenesis. We show that, in most oocytes, DNA DSB foci on the ZW are resolved by the end of pachytene and that the ZW desynapses in broad synchrony with the autosomes. We unexpectedly find that ZW pairing is highly error prone, with many oocytes failing to engage in ZW synapsis and crossover formation. Oocytes with unsynapsed Z and W chromosomes nevertheless progress to the diplotene stage, suggesting that a checkpoint does not operate during pachytene in the chicken germ line. Using a combination of epigenetic profiling and RNA-FISH analysis, we find no evidence for MSCI, associated with neither the asynaptic ZW, as described in mammals, nor the synaptic ZW. The lack of conservation of MSCI in the chicken reopens the debate about the evolution of MSCI and its driving forces.

  2. Error-prone ZW pairing and no evidence for meiotic sex chromosome inactivation in the chicken germ line.

    Directory of Open Access Journals (Sweden)

    Silvana Guioli

    Full Text Available In the male mouse the X and Y chromosomes pair and recombine within the small pseudoautosomal region. Genes located on the unsynapsed segments of the X and Y are transcriptionally silenced at pachytene by Meiotic Sex Chromosome Inactivation (MSCI. The degree to which MSCI is conserved in other vertebrates is currently unclear. In the female chicken the ZW bivalent is thought to undergo a transient phase of full synapsis at pachytene, starting from the homologous ends and spreading through the heterologous regions. It has been proposed that the repair of the ZW DNA double-strand breaks (DSBs is postponed until diplotene and that the ZW bivalent is subject to MSCI, which is independent of its synaptic status. Here we present a distinct model of meiotic pairing and silencing of the ZW pair during chicken oogenesis. We show that, in most oocytes, DNA DSB foci on the ZW are resolved by the end of pachytene and that the ZW desynapses in broad synchrony with the autosomes. We unexpectedly find that ZW pairing is highly error prone, with many oocytes failing to engage in ZW synapsis and crossover formation. Oocytes with unsynapsed Z and W chromosomes nevertheless progress to the diplotene stage, suggesting that a checkpoint does not operate during pachytene in the chicken germ line. Using a combination of epigenetic profiling and RNA-FISH analysis, we find no evidence for MSCI, associated with neither the asynaptic ZW, as described in mammals, nor the synaptic ZW. The lack of conservation of MSCI in the chicken reopens the debate about the evolution of MSCI and its driving forces.

  3. No severe and global X chromosome inactivation in meiotic male germline of Drosophila

    OpenAIRE

    Mikhaylova Lyudmila M; Nurminsky Dmitry I

    2012-01-01

    Abstract This article is a response to Vibranovski et al. See correspondence article http://www.biomedcentral.com/1741-7007/10/49 and the original research article http://www.biomedcentral.com/1741-7007/9/29 We have previously reported a high propensity of testis-expressed X-linked genes to activation in meiotic cells, a similarity in global gene expression between the X chromosome and autosomes in meiotic germline, and under-representation of various types of tissue-specific genes on the X c...

  4. Chromosome

    Science.gov (United States)

    Chromosomes are structures found in the center (nucleus) of cells that carry long pieces of DNA. DNA ... is the building block of the human body. Chromosomes also contain proteins that help DNA exist in ...

  5. The electrophoretic banding pattern of the chromosomes of Pichia stipitis and Candida shehatae.

    Science.gov (United States)

    Passoth, V; Hansen, M; Klinner, U; Emeis, C C

    1992-11-01

    The electrophoretic karyotype of fu1ur strains of P. stipitis and five strains of C. shehatae were compared by means of OFAGE and TAFE techniques. Although the number of chromosomal bands was six in all cases except one, P. stipitis revealed a clearly distinct pattern in comparison to C. shehatae. Both yeasts showed remarkable chromosome length polymorphism.

  6. Contrasting patterns of X/Y polymorphism distinguish Carica papaya from other sex chromosome systems.

    Science.gov (United States)

    Weingartner, Laura A; Moore, Richard C

    2012-12-01

    The sex chromosomes of the tropical crop papaya (Carica papaya) are evolutionarily young and consequently allow for the examination of evolutionary mechanisms that drive early sex chromosome divergence. We conducted a molecular population genetic analysis of four X/Y gene pairs from a collection of 45 wild papaya accessions. These population genetic analyses reveal striking differences in the patterns of polymorphism between the X and Y chromosomes that distinguish them from other sex chromosome systems. In most sex chromosome systems, the Y chromosome displays significantly reduced polymorphism levels, whereas the X chromosome maintains a level of polymorphism that is comparable to autosomal loci. However, the four papaya sex-linked loci that we examined display diversity patterns that are opposite this trend: the papaya X alleles exhibit significantly reduced polymorphism levels, whereas the papaya Y alleles maintain greater than expected levels of diversity. Our analyses suggest that selective sweeps in the regions of the X have contributed to this pattern while also revealing geographically restricted haplogroups on the Y. We discuss the possible role sexual selection and/or genomic conflict have played in shaping the contrasting patterns of polymorphism found for the papaya X and Y chromosomes.

  7. Changes in Nuclear Orientation Patterns of Chromosome 11 during Mouse Plasmacytoma Development

    Directory of Open Access Journals (Sweden)

    Ann-Kristin Schmälter

    2015-10-01

    Full Text Available Studying changes in nuclear architecture is a unique approach toward the understanding of nuclear remodeling during tumor development. One aspect of nuclear architecture is the orientation of chromosomes in the three-dimensional nuclear space. We studied mouse chromosome 11 in lymphocytes of [T38HxBALB/c]N mice with a reciprocal translocation between chromosome X and 11 (T38HT(X;11 exhibiting a long chromosome T(11;X and a short chromosome T(X;11 and in fast-onset plasmacytomas (PCTs induced in the same strain. We determined the three-dimensional orientation of chromosome 11 using a mouse chromosome 11 specific multicolor banding probe. We also examined the nuclear position of the small translocation chromosome T(X;11 which contains cytoband 11E2 and parts of E1. Chromosomes can point either with their centromeric or with their telomeric end toward the nuclear center or periphery, or their position is found in parallel to the nuclear border. In T38HT(X;11 nuclei, the most frequently observed orientation pattern was with both chromosomes 11 in parallel to the nuclear border (“PP”. PCT cells showed nuclei with two or more copies of chromosome 11. In PCTs, the most frequent orientation pattern was with one chromosome in parallel and the other pointing with its centromeric end toward the nuclear periphery (“CP”. There is a significant difference between the orientation patterns observed in T38HT(X;11 and in PCT nuclei (P < .0001.

  8. Stage-specific expression profiling of Drosophila spermatogenesis suggests that meiotic sex chromosome inactivation drives genomic relocation of testis-expressed genes.

    Science.gov (United States)

    Vibranovski, Maria D; Lopes, Hedibert F; Karr, Timothy L; Long, Manyuan

    2009-11-01

    In Drosophila, genes expressed in males tend to accumulate on autosomes and are underrepresented on the X chromosome. In particular, genes expressed in testis have been observed to frequently relocate from the X chromosome to the autosomes. The inactivation of X-linked genes during male meiosis (i.e., meiotic sex chromosome inactivation-MSCI) was first proposed to explain male sterility caused by X-autosomal translocation in Drosophila, and more recently it was suggested that MSCI might provide the conditions under which selection would favor the accumulation of testis-expressed genes on autosomes. In order to investigate the impact of MSCI on Drosophila testis-expressed genes, we performed a global gene expression analysis of the three major phases of D. melanogaster spermatogenesis: mitosis, meiosis, and post-meiosis. First, we found evidence supporting the existence of MSCI by comparing the expression levels of X- and autosome-linked genes, finding the former to be significantly reduced in meiosis. Second, we observed that the paucity of X-linked testis-expressed genes was restricted to those genes highly expressed in meiosis. Third, we found that autosomal genes relocated through retroposition from the X chromosome were more often highly expressed in meiosis in contrast to their X-linked parents. These results suggest MSCI as a general mechanism affecting the evolution of some testis-expressed genes.

  9. Stage-specific expression profiling of Drosophila spermatogenesis suggests that meiotic sex chromosome inactivation drives genomic relocation of testis-expressed genes.

    Directory of Open Access Journals (Sweden)

    Maria D Vibranovski

    2009-11-01

    Full Text Available In Drosophila, genes expressed in males tend to accumulate on autosomes and are underrepresented on the X chromosome. In particular, genes expressed in testis have been observed to frequently relocate from the X chromosome to the autosomes. The inactivation of X-linked genes during male meiosis (i.e., meiotic sex chromosome inactivation-MSCI was first proposed to explain male sterility caused by X-autosomal translocation in Drosophila, and more recently it was suggested that MSCI might provide the conditions under which selection would favor the accumulation of testis-expressed genes on autosomes. In order to investigate the impact of MSCI on Drosophila testis-expressed genes, we performed a global gene expression analysis of the three major phases of D. melanogaster spermatogenesis: mitosis, meiosis, and post-meiosis. First, we found evidence supporting the existence of MSCI by comparing the expression levels of X- and autosome-linked genes, finding the former to be significantly reduced in meiosis. Second, we observed that the paucity of X-linked testis-expressed genes was restricted to those genes highly expressed in meiosis. Third, we found that autosomal genes relocated through retroposition from the X chromosome were more often highly expressed in meiosis in contrast to their X-linked parents. These results suggest MSCI as a general mechanism affecting the evolution of some testis-expressed genes.

  10. Replication Banding Patterns in Human Chromosomes Detected Using 5-ethynyl-2'-deoxyuridine Incorporation.

    Science.gov (United States)

    Hoshi, Osamu; Ushiki, Tatsuo

    2011-10-26

    A novel technique using the incorporation of 5-ethynyl-2'-deoxyuridine (EdU) into replicating DNA is described for the analysis of replicating banding patterns of human metaphase chromosomes. Human lymphocytes were synchronized with excess thymidine and treated with EdU during the late S phase of the cell cycle. The incorporated EdU was then detected in metaphase chromosomes using Alexa Fluor® 488 azides, through the 1,3-dipolar cycloaddition reaction of organic azides with the terminal acetylene group of EdU. Chromosomes with incorporated EdU showed a banding pattern similar to G-banding of normal human chromosomes. Imaging by atomic force microscopy (AFM) in liquid conditions showed that the structure of the chromosomes was well preserved even after EdU treatment. Comparison between fluorescence microscopy and AFM images of the same chromosome 1 indicated the presence of ridges and grooves in the chromatid arm, features that have been previously reported in relation to G-banding. These results suggest an intimate relationship between EdU-induced replication bands and G- or R-bands in human chromosomes. This technique is thus useful for analyzing the structure of chromosomes in relation to their banding patterns following DNA replication in the S phase.

  11. Giemsa C-banding of Barley Chromosomes. I: Banding Pattern Polymorphism

    DEFF Research Database (Denmark)

    Linde-Laursen, Ib

    1978-01-01

    Twenty barley (Hordeum vulgare) lines studied had a common basic chromosome banding pattern. Most bands ranged from medium to very small in size. The most conspicuous banding occurred at or near the centromeres, in the proximal, intercalary parts of most chromosome arms and beside the secondary c...... 7. Seventeen differently banded karyotypes were found. Some banding pattern polymorphisms can be used in cytological and cytogenetic studies....

  12. Trans-inactivation: Repression in a wrong place.

    Science.gov (United States)

    Shatskikh, Aleksei S; Abramov, Yuriy A; Lavrov, Sergey A

    2016-08-19

    Trans-inactivation is the repression of genes on a normal chromosome under the influence of a rearranged homologous chromosome demonstrating the position effect variegation (PEV). This phenomenon was studied in detail on the example of brown(Dominant) allele causing the repression of wild-type brown gene on the opposite chromosome. We have investigated another trans-inactivation-inducing chromosome rearrangement, In(2)A4 inversion. In both cases, brown(Dominant) and In(2)A4, the repression seems to be the result of dragging of the euchromatic region of the normal chromosome into the heterochromatic environment. It was found that cis-inactivation (classical PEV) and trans-inactivation show different patterns of distribution along the chromosome and respond differently to PEV modifying genes. It appears that the causative mechanism of trans-inactivation is de novo heterochromatin assembly on euchromatic sequences dragged into the heterochromatic nuclear compartment. Trans-inactivation turns out to be the result of a combination of heterochromatin-induced position effect and the somatic interphase chromosome pairing that is widespread in Diptera.

  13. [Chromosome CPD(PI/DAPI)- and CMA/DAPI-banding patterns in Allium cepa L].

    Science.gov (United States)

    Kim, E S; Punina, E O; Rodionov, A V

    2002-04-01

    Chromosome banding patterns of Allium cepa L. were obtained by using fluorochrome combinations chromomycin A3 (CMA) + 4',6-diamidino-2-phenylindole (DAPI), DAPI + actinomycin D (AMD) and propidium iodide (PI) + DAPI. In A. cepa, telomeric heterochromatin displayed dull fluorescence after staining with DAPI and DAPI/AMD. After staining with the GC-specific CMA and AT-specific DAPI, the CMA-positive fluorescence of the NOR region and the telomeric bands of C-heterochromatin was observed. In combination with DAPI, PI, a dye with low AT/GC specificity, produced almost uniform fluorescence of chromosomal arms and heterochromatin, whereas the NOR-adjoining regions displayed bright fluorescence. Denaturation of chromosomal DNA (95 degrees C for 1-3 min) followed by renaturation in the 2 x SSC buffer (37 degrees C, 12 h) altered the chromosome fluorescence patterns: specific PI-positive bands appeared and the contrast of CMA-banding increased. Bright fluorescence of the NOR and adjoining regions was also observed in the case. Three-minute denaturation led also to a bright PI-positive fluorescence of telomeric heterochromatin. The denaturation of chromosomal DNA before staining results in changes of the DAPI fluorescence pattern and in the appearance of DAPI fluorescence in GR-rich NOP regions. The mechanisms underlying the effects of denaturation/renaturation procedures on chromosome banding patterns obtained with different fluorochromes are discussed.

  14. Spread of X-chromosome inactivation into chromosome 15 is associated with Prader-Willi syndrome phenotype in a boy with a t(X;15)(p21.1;q11.2) translocation.

    Science.gov (United States)

    Sakazume, Satoru; Ohashi, Hirofumi; Sasaki, Yuki; Harada, Naoki; Nakanishi, Katsumi; Sato, Hidenori; Emi, Mitsuru; Endoh, Kazushi; Sohma, Ryoichi; Kido, Yasuhiro; Nagai, Toshiro; Kubota, Takeo

    2012-01-01

    X-chromosome inactivation (XCI) is an essential mechanism in females that compensates for the genome imbalance between females and males. It is known that XCI can spread into an autosome of patients with X;autosome translocations. The subject was a 5-year-old boy with Prader-Willi syndrome (PWS)-like features including hypotonia, hypo-genitalism, hypo-pigmentation, and developmental delay. G-banding, fluorescent in situ hybridization, BrdU-incorporated replication, human androgen receptor gene locus assay, SNP microarrays, ChIP-on-chip assay, bisulfite sequencing, and real-time RT-PCR were performed. Cytogenetic analyses revealed that the karyotype was 46,XY,der(X)t(X;15)(p21.1;q11.2),-15. In the derivative chromosome, the X and half of the chromosome 15 segments showed late replication. The X segment was maternal, and the chromosome 15 region was paternal, indicating its post-zygotic origin. The two chromosome 15s had a biparental origin. The DNA methylation level was relatively high in the region proximal from the breakpoint, and the level decreased toward the middle of the chromosome 15 region; however, scattered areas of hypermethylation were found in the distal region. The promoter regions of the imprinted SNRPN and the non-imprinted OCA2 genes were completely and half methylated, respectively. However, no methylation was found in the adjacent imprinted gene UBE3A, which contained a lower density of LINE1 repeats. Our findings suggest that XCI spread into the paternal chromosome 15 led to the aberrant hypermethylation of SNRPN and OCA2 and their decreased expression, which contributes to the PWS-like features and hypo-pigmentation of the patient. To our knowledge, this is the first chromosome-wide methylation study in which the DNA methylation level is demonstrated in an autosome subject to XCI.

  15. Over-expression of XIST, the Master Gene for X Chromosome Inactivation, in Females With Major Affective Disorders

    Science.gov (United States)

    Ji, Baohu; Higa, Kerin K.; Kelsoe, John R.; Zhou, Xianjin

    2015-01-01

    Background Psychiatric disorders are common mental disorders without a pathological biomarker. Classic genetic studies found that an extra X chromosome frequently causes psychiatric symptoms in patients with either Klinefelter syndrome (XXY) or Triple X syndrome (XXX). Over-dosage of some X-linked escapee genes was suggested to cause psychiatric disorders. However, relevance of these rare genetic diseases to the pathogenesis of psychiatric disorders in the general population of psychiatric patients is unknown. Methods XIST and several X-linked genes were studied in 36 lymphoblastoid cell lines from healthy females and 60 lymphoblastoid cell lines from female patients with either bipolar disorder or recurrent major depression. XIST and KDM5C expression was also quantified in 48 RNA samples from postmortem human brains of healthy female controls and female psychiatric patients. Findings We found that the XIST gene, a master in control of X chromosome inactivation (XCI), is significantly over-expressed (p = 1 × 10− 7, corrected after multiple comparisons) in the lymphoblastoid cells of female patients with either bipolar disorder or major depression. The X-linked escapee gene KDM5C also displays significant up-regulation (p = 5.3 × 10− 7, corrected after multiple comparisons) in the patients' cells. Expression of XIST and KDM5C is highly correlated (Pearson's coefficient, r = 0.78, p = 1.3 × 10− 13). Studies on human postmortem brains supported over-expression of the XIST gene in female psychiatric patients. Interpretations We propose that over-expression of XIST may cause or result from subtle alteration of XCI, which up-regulates the expression of some X-linked escapee genes including KDM5C. Over-expression of X-linked genes could be a common mechanism for the development of psychiatric disorders between patients with those rare genetic diseases and the general population of female psychiatric patients with XIST over-expression. Our studies

  16. Chromosomal banding patterns in patients with acute nonlymphocytic leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Testa, J.R.; Rowley, J.D.

    1980-01-01

    Approximately 50% of acute nonlymphocytic leukemia (ANLL) patients studied with banding techniques have detectable clonal karyotypic abnormalities. Although there is considerable variability, certain nonrandom abnormalities are observed, including trisomy 8, monosomy 7, and the 8;21 translocation (frequently accompanied by loss of an X or Y). The 15;17 translocation is highly specific for acute promyelocytic leukemia. Clonal evolution of the karyotype can be observed in a significant number of ANLL patients for whom serial cytogenetic analyses are obtained. Gain of a No. 8 is the most frequently observed evolutionary change. Bone marrow cells from paients who develop ANLL following treatment of a previous malignancy often have hypodiploid modal numbers and frequently show loss of all or part of a chromosome No. 5 or No. 7.

  17. Chromosomal evolution and patterns of introgression in helianthus.

    Science.gov (United States)

    Barb, Jessica G; Bowers, John E; Renaut, Sebastien; Rey, Juan I; Knapp, Steven J; Rieseberg, Loren H; Burke, John M

    2014-07-01

    Knowledge of the nature and extent of karyotypic differences between species provides insight into the evolutionary history of the genomes in question and, in the case of closely related species, the potential for genetic exchange between taxa. We constructed high-density genetic maps of the silverleaf sunflower (Helianthus argophyllus) and Algodones Dune sunflower (H. niveus ssp. tephrodes) genomes and compared them to a consensus map of cultivated sunflower (H. annuus) to identify chromosomal rearrangements between species. The genetic maps of H. argophyllus and H. niveus ssp. tephrodes included 17 linkage groups each and spanned 1337 and 1478 cM, respectively. Comparative analyses revealed greater divergence between H. annuus and H. niveus ssp. tephrodes (13 inverted segments, 18 translocated segments) than between H. annuus and H. argophyllus (10 inverted segments, 8 translocated segments), consistent with their known phylogenetic relationships. Marker order was conserved across much of the genome, with 83 and 64% of the H. argophyllus and H. niveus ssp. tephrodes genomes, respectively, being syntenic with H. annuus. Population genomic analyses between H. annuus and H. argophyllus, which are sympatric across a portion of the natural range of H. annuus, revealed significantly elevated genetic structure in rearranged portions of the genome, indicating that such rearrangements are associated with restricted gene flow between these two species.

  18. No link between X chromosome inactivation pattern and simple goiter in females

    DEFF Research Database (Denmark)

    Brix, Thomas Heiberg; Hansen, Pia Skov; Knudsen, Gun Peggy S

    2009-01-01

    BACKGROUND: Simple goiter (SG) comprises diffuse (DG) and nodular (NG) benign nonautoimmune nontoxic goiter. In nonendemic goiter areas, the ratio of females to males may exceed 5:1, indicating that gender and/or sex hormones may play a role in the etiology of SG in these areas. Theoretically, as...

  19. Late-replicating X-chromosome: replication patterns in mammalian females

    Directory of Open Access Journals (Sweden)

    Tunin Karen

    2002-01-01

    Full Text Available The GTG-banding and 5-BrdU incorporation patterns of the late-replicating X-chromosome were studied in female dogs and cattle, and compared to human female patterns. The replication patterns of the short arm of the X-chromosomes did not show any difference between human, dog and cattle females. As to the long arm, some bands showed differences among the three studied species regarding the replication kinetics pattern. These differences were observed in a restricted region of the X-chromosome, delimited by Xq11 -> q25 in humans, by Xq1 -> q8 in dogs, and by Xq12 -> q32 in cattle. In an attempt to find out if these differences in the replication kinetics could be a reflection of differences in the localization of genes in that region of the X-chromosome, we used the probe for the human androgen receptor gene (AR localized at Xq12, which is in the region where we observed differences among the three studied species. We did not, however, observe hybridization signals. Our study goes on, using other human probes for genes located in the region Xq11 -> Xq25.

  20. Replication Banding Patterns in Human Chromosomes Detected Using 5-ethynyl-2'-deoxyuridine Incorporation

    OpenAIRE

    Hoshi, Osamu; Ushiki, Tatsuo

    2011-01-01

    A novel technique using the incorporation of 5-ethynyl-2'-deoxyuridine (EdU) into replicating DNA is described for the analysis of replicating banding patterns of human metaphase chromosomes. Human lymphocytes were synchronized with excess thymidine and treated with EdU during the late S phase of the cell cycle. The incorporated EdU was then detected in metaphase chromosomes using Alexa Fluor® 488 azides, through the 1,3-dipolar cycloaddition reaction of organic azides with the terminal acety...

  1. Pattern of X-Y chromosome pairing in the Taiwan vole, Microtus kikuchii.

    Science.gov (United States)

    Mekada, K; Harada, M; Lin, L K; Koyasu, K; Borodin, P M; Oda, S I

    2001-02-01

    Pairing of X and Y chromosomes at meiotic prophase and the G- and C-banding patterns and nucleolar organizer region (NOR) distribution were analyzed in Microtus kikuchii. M. kikuchii is closely related to M. oeconomus and M. montebelli, karyologically and systematically. The formation of a synaptonemal complex between the X and Y chromosomes at pachytene and end-to-end association at diakinesis--metaphase I are only observed in three species in the genus Microtus; M. kikuchii, M. oeconomus, and M. montebelli. All the other species that have been studied so far have had asynaptic X-Y chromosomes. These data confirm that M. kikuchii, M. oeconomus, and M. montebelli are very closely related, and support the separation of asynaptic and synaptic groups on the phylogenetic tree.

  2. Automatically inferred Markov network models for classification of chromosomal band pattern structures.

    Science.gov (United States)

    Granum, E; Thomason, M G

    1990-01-01

    A structural pattern recognition approach to the analysis and classification of metaphase chromosome band patterns is presented. An operational method of representing band pattern profiles as sharp edged idealized profiles is outlined. These profiles are nonlinearly scaled to a few, but fixed number of "density" levels. Previous experience has shown that profiles of six levels are appropriate and that the differences between successive bands in these profiles are suitable for classification. String representations, which focuses on the sequences of transitions between local band pattern levels, are derived from such "difference profiles." A method of syntactic analysis of the band transition sequences by dynamic programming for optimal (maximal probability) string-to-network alignments is described. It develops automatic data-driven inference of band pattern models (Markov networks) per class, and uses these models for classification. The method does not use centromere information, but assumes the p-q-orientation of the band pattern profiles to be known a priori. It is experimentally established that the method can build Markov network models, which, when used for classification, show a recognition rate of about 92% on test data. The experiments used 200 samples (chromosome profiles) for each of the 22 autosome chromosome types and are designed to also investigate various classifier design problems. It is found that the use of a priori knowledge of Denver Group assignment only improved classification by 1 or 2%. A scheme for typewise normalization of the class relationship measures prove useful, partly through improvements on average results and partly through a more evenly distributed error pattern. The choice of reference of the p-q-orientation of the band patterns is found to be unimportant, and results of timing of the execution time of the analysis show that recent and efficient implementations can process one cell in less than 1 min on current standard

  3. The Pluripotency Factor-Bound Intron 1 of Xist Is Dispensable for X Chromosome Inactivation and Reactivation In Vitro and In Vivo

    Directory of Open Access Journals (Sweden)

    Alissa Minkovsky

    2013-03-01

    Full Text Available X chromosome inactivation (XCI is a dynamically regulated developmental process with inactivation and reactivation accompanying the loss and gain of pluripotency, respectively. A functional relationship between pluripotency and lack of XCI has been suggested, whereby pluripotency transcription factors repress the master regulator of XCI, the noncoding transcript Xist, by binding to its first intron (intron 1. To test this model, we have generated intron 1 mutant embryonic stem cells (ESCs and two independent mouse models. We found that Xist’s repression in ESCs, its transcriptional upregulation upon differentiation, and its silencing upon reprogramming to pluripotency are not dependent on intron 1. Although we observed subtle effects of intron 1 deletion on the randomness of XCI and in the absence of the antisense transcript Tsix in differentiating ESCs, these have little relevance in vivo because mutant mice do not deviate from Mendelian ratios of allele transmission. Altogether, our findings demonstrate that intron 1 is dispensable for the developmental dynamics of Xist expression.

  4. Familial-skewed X-chromosome inactivation as a predisposing factor for late-onset X-linked sideroblastic anemia in carrier females.

    Science.gov (United States)

    Cazzola, M; May, A; Bergamaschi, G; Cerani, P; Rosti, V; Bishop, D F

    2000-12-15

    X-linked sideroblastic anemia (XLSA) is caused by mutations in the erythroid-specific 5-aminolevulinic acid synthase (ALAS2) gene. An elderly woman who presented with an acquired sideroblastic anemia is studied. Molecular analysis revealed that she was heterozygous for a missense mutation in the ALAS2 gene, but she expressed only the mutated gene in reticulocytes. Her 2 daughters and a granddaughter were heterozygous for this mutation, had normal hemoglobin levels, and expressed the normal ALAS2 gene in reticulocytes. A grandson with a previous diagnosis of thalassemia intermedia was found to be hemizygous for the ALAS2 mutation. Treatment with pyridoxine completely corrected the anemia both in the proband and her grandson. All women who were analyzed in this family showed skewed X-chromosome inactivation in leukocytes, which indicated a hereditary condition associated with unbalanced lyonization. Because the preferentially active X chromosome carried the mutant ALAS2 allele, acquired skewing in the elderly likely worsened the genetic condition and abolished the normal ALAS2 allele expression in the proband. (Blood. 2000;96:4363-4365)

  5. The effects of exposure to different clastogens on the pattern of chromosomal aberrations detected by FISH whole chromosome painting in occupationally exposed individuals

    Energy Technology Data Exchange (ETDEWEB)

    Beskid, O. [Institute of Experimental Medicine AS CR and Health Institute of Central Bohemia, Videnska 1083, 142 20 Prague 4 (Czech Republic); Dusek, Z. [Institute of Experimental Medicine AS CR and Health Institute of Central Bohemia, Videnska 1083, 142 20 Prague 4 (Czech Republic); Solansky, I. [Institute of Experimental Medicine AS CR and Health Institute of Central Bohemia, Videnska 1083, 142 20 Prague 4 (Czech Republic); Sram, R.J. [Institute of Experimental Medicine AS CR and Health Institute of Central Bohemia, Videnska 1083, 142 20 Prague 4 (Czech Republic)]. E-mail: sram@biomed.cas.cz

    2006-02-22

    The pattern of chromosomal aberrations (CA) was studied by fluorescence in situ hybridization (FISH) technique (whole chromosomes 1 and 4 painting) in workers occupationally exposed to any of the four following conditions: acrylonitrile (ACN), ethyl benzene (EB), carcinogenic polycyclic aromatic hydrocarbons (c-PAHs), and irradiation in nuclear power plants (NPP), respectively. Decrease in the relative frequency of translocations was observed in EB group, and an increase in reciprocal translocations in ACN and NPP-exposed groups. An increase in a relative number of insertions was registered under all four conditions (significant at ACN, EB, c-PAHs, quasisignificant at NPP-exposed groups). Significant differences in the percentage of lymphocytes with aberrations on chromosome 1 (58.8 {+-} 32.7%, versus 73.8 {+-} 33.6% in the controls, P < 0.05), and chromosome 4 (47.0 {+-} 34.1%, versus 29.4 {+-} 32.2%, P < 0.01) were found in workers exposed to ACN. Similarly, a decrease in the proportion of cells with aberration on chromosome 1 (61.0 {+-} 24.0%, versus 73.8 {+-} 33.6%, P < 0.05) and an increase on chromosome 4 (45.6 {+-} 24.6%, versus 29.4 {+-} 32.2%, P < 0.05) were observed in workers exposed to EB. Frequency of aberrant cells (%AB.C.) as well as genomic frequency of translocations (F {sub G}/100) increased with age (P < 0.001). Aging also increased the percentage of translocations and reciprocal translocations (P < 0.05), but decreased the relative number of acentric fragments (P < 0.01). Smoking led to significantly increased F {sub G}/100 (P < 0.05), but did not affect the pattern of chromosomal aberrations. Our results seem to indicate that different carcinogens may induce a different pattern of chromosomal aberrations.

  6. Pattern of chromosome involvement in childhood hyperdiploid pre-B-cell acute lymhoblastic leukemia cases from India

    Directory of Open Access Journals (Sweden)

    Lily S. Kerketta

    2014-01-01

    Conclusion: In this study, the pattern of chromosome involvement in hyperdiploid karyotype of ALL patients is same as other studies except some chromosomes like 1, 6, 11, 12, 19 and 22 have some more frequent involvement than other studies. This study also showed the occurrence of TEL/AML1 fusion is more (19.8% than other reports from India.

  7. Chromosomal organization of simple sequence repeats in the Pacific oyster (Crassostrea gigas): (GGAT)4, (GT)7 and (TA)10 chromosome patterns

    Indian Academy of Sciences (India)

    K. Bouilly; R. Chaves; A. Leitão; A. Benabdelmouna; H. Guedes-Pinto

    2008-08-01

    Chromosome identification is essential in oyster genomic research. Fluorescence in situ hybridization (FISH) offers new opportunities for the identification of oyster chromosomes. It has been used to locate satellite DNAs, telomeres or ribosomal DNA sequences. However, regarding chromosome identification, no study has been conducted with simple sequence repeats (SSRs). FISH was used to probe the physical organization of three particular SSRs, (GGAT)4, (GT)7 and (TA)10 onto metaphase chromosomes of the Pacific oyster, Crassostrea gigas. Hybridization signals were observed in all the SSR probes, but the distribution and intensity of signals varied according to the oligonucleotide repeat. The intercalary, centromeric and telomeric bands were observed along the chromosomes, and for each particular repeat every chromosome pair presented a similar pattern, allowing karyotypic analysis with all the SSRs tested. Our study is the first in mollusks to show the application of SSR in situ hybridization for chromosome identification and karyotyping. This technique can be a useful tool for oyster comparative studies and to understand genome organization in different oyster taxa.

  8. Inactivation of Cdk1/Cyclin B in metaphase-arrested mouse FT210 cells induces exit from mitosis without chromosome segregation or cytokinesis and allows passage through another cell cycle.

    Science.gov (United States)

    Paulson, James R

    2007-04-01

    It is well known that inactivation of Cdk1/Cyclin B is required for cells to exit mitosis. The work reported here tests the hypothesis that Cdk1/Cyclin B inactivation is not only necessary but also sufficient to induce mitotic exit and reestablishment of the interphase state. This hypothesis predicts that inactivation of Cdk1 in metaphase-arrested cells will induce the M to G1-phase transition. It is shown that when mouse FT210 cells (in which Cdk1 is temperature-sensitive) are arrested in metaphase and then shifted to their non-permissive temperature, they rapidly exit mitosis as evidenced by reassembly of interphase nuclei, decondensation of chromosomes, and dephosphorylation of histones H1 and H3. The resulting interphase cells are functionally normal as judged by their ability to progress through another cell cycle. However, they have double the normal number of chromosomes because they previously bypassed anaphase, chromosome segregation, and cytokinesis. These results, taken together with other observations in the literature, strongly suggest that in mammalian cells, inactivation of Cdk1/cyclin B is the trigger for mitotic exit and reestablishment of the interphase state.

  9. 5meCpG epigenetic marks neighboring a primate-conserved core promoter short tandem repeat indicate X-chromosome inactivation.

    Directory of Open Access Journals (Sweden)

    Filipe Brum Machado

    Full Text Available X-chromosome inactivation (XCI is the epigenetic transcriptional silencing of an X-chromosome during the early stages of embryonic development in female eutherian mammals. XCI assures monoallelic expression in each cell and compensation for dosage-sensitive X-linked genes between females (XX and males (XY. DNA methylation at the carbon-5 position of the cytosine pyrimidine ring in the context of a CpG dinucleotide sequence (5meCpG in promoter regions is a key epigenetic marker for transcriptional gene silencing. Using computational analysis, we revealed an extragenic tandem GAAA repeat 230-bp from the landmark CpG island of the human X-linked retinitis pigmentosa 2 RP2 promoter whose 5meCpG status correlates with XCI. We used this RP2 onshore tandem GAAA repeat to develop an allele-specific 5meCpG-based PCR assay that is highly concordant with the human androgen receptor (AR exonic tandem CAG repeat-based standard HUMARA assay in discriminating active (Xa from inactive (Xi X-chromosomes. The RP2 onshore tandem GAAA repeat contains neutral features that are lacking in the AR disease-linked tandem CAG repeat, is highly polymorphic (heterozygosity rates approximately 0.8 and shows minimal variation in the Xa/Xi ratio. The combined informativeness of RP2/AR is approximately 0.97, and this assay excels at determining the 5meCpG status of alleles at the Xp (RP2 and Xq (AR chromosome arms in a single reaction. These findings are relevant and directly translatable to nonhuman primate models of XCI in which the AR CAG-repeat is monomorphic. We conducted the RP2 onshore tandem GAAA repeat assay in the naturally occurring chimeric New World monkey marmoset (Callitrichidae and found it to be informative. The RP2 onshore tandem GAAA repeat will facilitate studies on the variable phenotypic expression of dominant and recessive X-linked diseases, epigenetic changes in twins, the physiology of aging hematopoiesis, the pathogenesis of age-related hematopoietic

  10. DNA Ploidy and Chromosome (FISH Pattern Analysis of Peripheral Nerve Sheath Tumors

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    Anett Hruska

    2004-01-01

    Full Text Available Background and methods: 44 peripheral nerve sheath tumors (PNST (27 schwannomas, 9 neurofibromas and 8 malignant peripheral nerve sheath tumors (MPNST were analyzed to determine DNA ploidy pattern and to clarify the conflicting data in the literature concerning this topic (whether benign PNSTs are aneuploid or not. For further insight we analyzed 6 schwannomas, one atypical neurofibroma and five MPNSTs by fluorescence in situ hybridization (FISH technique using centromeric chromosome probes (7, 17 and 18 and automatic image analysis station, Metafer 4. Results: Benign schwannomas (including the problematic variants as ancient, cellular, neuroblastoma like and multiplex schwannomas could be characterized by euploid‐polyploidisation and by their 4c peak height value which was usually more than 10% of total cell number measured. These characters were not found among neurofibromas and MPNST‐s. FISH analysis revealed and confirmed that the ‘normal’ euploid–polyploid cells are mainly eusomic–polysomic containing two, four, eight or sixteen signals for each chromosomes examined, but in a small proportion aneusomy was found among tumor cells of benign schwannomas (average: 2.58; range 1.33–3.44. In contrast, the atypical neurofibroma displayed marked aneusomy (18.44% but it contained normal eusomic and polysomic cells too. Two diploid MPNSTs proved to be clearly aneusomic with trisomy of chromosome 17 and monosomy of chromosome 18. Conclusions: All these data suggest that ploidy pattern determination combined with FISH analysis may be a very useful supplementary tool for making a right diagnosis (to differentiate benign versus malignant schwannomas in problematic variants and to understand better the malignant transformation in PNSTs.

  11. Genes that escape from X inactivation.

    Science.gov (United States)

    Berletch, Joel B; Yang, Fan; Xu, Jun; Carrel, Laura; Disteche, Christine M

    2011-08-01

    To achieve a balanced gene expression dosage between males (XY) and females (XX), mammals have evolved a compensatory mechanism to randomly inactivate one of the female X chromosomes. Despite this chromosome-wide silencing, a number of genes escape X inactivation: in women about 15% of X-linked genes are bi-allelically expressed and in mice, about 3%. Expression from the inactive X allele varies from a few percent of that from the active allele to near equal expression. While most genes have a stable inactivation pattern, a subset of genes exhibit tissue-specific differences in escape from X inactivation. Escape genes appear to be protected from the repressive chromatin modifications associated with X inactivation. Differences in the identity and distribution of escape genes between species and tissues suggest a role for these genes in the evolution of sex differences in specific phenotypes. The higher expression of escape genes in females than in males implies that they may have female-specific roles and may be responsible for some of the phenotypes observed in X aneuploidy.

  12. Vanadate triggers the transition from chromosome condensation to decondensation in a mitotic mutant (tsTM13) inactivation of p34cdc2/H1 kinase and dephosphorylation of mitosis-specific histone H3.

    Science.gov (United States)

    Ajiro, K; Yasuda, H; Tsuji, H

    1996-11-01

    At the nonpermissive temperature (39 degrees C), chromosomes remain condensed in a temperature-sensitive cell mutant (tsTM13) arrested in the late stage of mitosis. Highly increased activity of histone H1 kinase, hyperphosphorylation of histone H1, and mitosis-specific histone H3 phosphorylation are maintained, even in telophase. In the present study, the defect of chromosome decondensation in tsTM13 cells was found to be partially normalized by a tyrosine phosphatase inhibitor, vanadate, with induction of chromosome decondensation and the formation of multinucleated cells. In the presence of vanadate, the H1 kinase activity dropped to near normal levels and the amount of the inactive from of p34cdc2 protein phosphorylated at a tyrosine residue was increased. H1 and H3 were also extensively de- phosphorylated, the latter being tightly associated with chromosome decondensation. Serine/threonine-protein phosphatase in late mitosis of the mutant works normally at 39 degrees C. The results indicate that (a) the genetic defect in the mutant may be involved in the control mechanism of the p34cdc2/H1 kinase activity in the late M phase rather than the phosphatase, (b) normalization of the defect of the mutant by vanadate results from inactivation of H1 kinase, and (c) late mitosis-specific events (p34cdc2/H1 kinase inactivation, mitosis-specific dephosphorylation of histone H1 and H3) are closely operating with chromosome decondensation.

  13. X inactivation in Rett syndrome: A preliminary study showing partial preferential inactivation of paternal X with the M27{beta} probe

    Energy Technology Data Exchange (ETDEWEB)

    Camus, P.; Abbadi, N.; Gilgenkrantz, S. [Laboratoire de Genetique, Vandoeuvre les Nancy (France)

    1994-04-15

    Rett syndrome (RS) is a severe progressive neurological disorder occurring exclusively in females. Most cases are sporadic. The few familial cases (less than 1%) cannot be explained by a simple mode of inheritance. Several hypotheses have been proposed: X-linked male lethal mutation, maternal uniparental disomy, fresh mutation on the X chromosome, involvement of mitochondrial DNA and differential inactivation with metabolic interference of X-borne alleles. The authors have examined the pattern of X inactivation in 10 affected girls who were selected according to the clinical criteria previously described and accepted by the French Rett Scientific Committee. The X inactivation pattern was studied by analysis of methylation at the hypervariable locus DXS255 with the M27{beta} probe. The results show a more-or-less skewed inactivation of paternal X in 8 Rett females, and 2 cases of symmetrical inactivation. In control girls, inactivation was symmetrical cases and the maternal X has been preferentially inactivated in the other 2 cases. In no case was a total skewed inactivation observed. Though there was clear evidence for a preferential paternal X inactivation that was statistically significant further studies are necessary to establish a relationship between X inactivation pattern and Rett syndrome.

  14. Complexities of X chromosome inactivation status in female human induced pluripotent stem cells-a brief review and scientific update for autism research.

    Science.gov (United States)

    Dandulakis, Mary G; Meganathan, Kesavan; Kroll, Kristen L; Bonni, Azad; Constantino, John N

    2016-01-01

    Induced pluripotent stem cells (iPSCs) allow researchers to make customized patient-derived cell lines by reprogramming noninvasively retrieved somatic cells. These cell lines have the potential to faithfully represent an individual's genetic background; therefore, in the absence of available human brain tissue from a living patient, these models have a significant advantage relative to other models of neurodevelopmental disease. When using human induced pluripotent stem cells (hiPSCs) to model X-linked developmental disorders or inherited conditions that undergo sex-specific modulation of penetrance (e.g., autism spectrum disorders), there are significant complexities in the course and status of X chromosome inactivation (XCI) that are crucial to consider in establishing the validity of cellular models. There are major gaps and inconsistencies in the existing literature regarding XCI status during the derivation and maintenance of hiPSCs and their differentiation into neurons. Here, we briefly describe the importance of the problem, review the findings and inconsistencies of the existing literature, delineate options for specifying XCI status in clonal populations, and develop recommendations for future studies.

  15. Atomic force microscopy for analyzing metaphase chromosomes: comparison of AFM images with fluorescence labeling images of banding patterns.

    Science.gov (United States)

    Hoshi, Osamu; Ushiki, Tatsuo

    2014-01-01

    The combined use of fluorescence microscopy with atomic force microscopy (AFM) has been introduced to analyze the replication-banding patterns of human chromosomes. Human lymphocytes synchronized with excess thymidine are treated with 5-ethynyl-2'-deoxyuridine (EdU) during the late S phase. EdU-labeled DNA is detected in metaphase chromosomes using Alexa Fluor 488(®) azide, through the 1,3-dipolar cycloaddition reaction of organic azides with the terminal acetylene group of EdU. Chromosomes with EdU incorporated during the late S phase show a banding pattern similar to the G-banding pattern of normal human chromosomes. The comparison between the fluorescence and AFM image of the same chromosome indicates the presence of ridges and grooves in the chromatid arms, which correspond to G-positive and G-negative bands, respectively. This technique of EdU-labeled replication bands combined with AFM is useful to analyze the structure of chromosomes in relation to the banding pattern.

  16. Conserved Patterns of Sex Chromosome Dosage Compensation in the Lepidoptera (WZ/ZZ): Insights from a Moth Neo-Z Chromosome

    Science.gov (United States)

    Walters, James R.; Knipple, Douglas C.

    2017-01-01

    Where previously described, patterns of sex chromosome dosage compensation in the Lepidoptera (moths and butterflies) have several unusual characteristics. Other female-heterogametic (ZW/ZZ) species exhibit female Z-linked expression that is reduced compared with autosomal expression and male Z expression. In the Lepidoptera, however, Z expression typically appears balanced between sexes but overall reduced relative to autosomal expression, that is Z ≈ ZZ sex chromosome dosage compensation. Moreover, conflicting results linger due to discrepancies in data analyses and tissues sampled among lepidopterans. To address these issues, we performed RNA-seq to analyze sex chromosome dosage compensation in the codling moth, Cydia pomonella, which is a species from the earliest diverging lepidopteran lineage yet examined for dosage compensation and has a neo-Z chromosome resulting from an ancient Z:autosome fusion. While supported by intraspecific analyses, the Z ≈ ZZ sex chromosome dosage compensation and the emerging view of the association of dosage compensation with sexual heterogamety. PMID:28338816

  17. Molecular patterns of X chromosome-linked color vision genes among 134 menof European ancestry

    Energy Technology Data Exchange (ETDEWEB)

    Drummond-Borg, M.; Deeb, S.S.; Motulsky, A.G. (Univ. of Washington, Seattle (USA))

    1989-02-01

    The authors used Southern blot hybridization to study X chromosome-linked color vision genes encoding the apoproteins of red and green visual pigments in 134 unselected Caucasian men. One hundred and thirteen individuals (84.3%) had a normal arrangement of their color vision pigment genes. All had one red pigment gene; the number of green pigment genes ranged from one to five with a mode of two. The frequency of molecular genotypes indicative of normal color vision (84.3%) was significantly lower than had been observed in previous studies of color vision phenotypes. Color vision defects can be due to deletions of red or green pigment genes or due to formation of hybrid genes comprising portions of both red and green pigment genes. Characteristic anomalous patterns were seen in 15 (11.2%) individuals: 7 (5.2%) had patterns characteristic of deuteranomaly, 2 (1.5%) had patterns characteristic of deuteranopia, and 6 (4.5%) had protan patterns. Previously undescribed hybrid gene patterns consisting of both green and red pigment gene fragments in addition to normal red and green genes were observed in another 6 individuals (4.5%). Thus, DNA testing detected anomalous color vision pigment genes at a higher frequency than expected from phenotypic color vision tests.

  18. Complex patterns of chromosome 11 aberrations in myeloid malignancies target CBL, MLL, DDB1 and LMO2.

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    Thorsten Klampfl

    Full Text Available Exome sequencing of primary tumors identifies complex somatic mutation patterns. Assignment of relevance of individual somatic mutations is difficult and poses the next challenge for interpretation of next generation sequencing data. Here we present an approach how exome sequencing in combination with SNP microarray data may identify targets of chromosomal aberrations in myeloid malignancies. The rationale of this approach is that hotspots of chromosomal aberrations might also harbor point mutations in the target genes of deletions, gains or uniparental disomies (UPDs. Chromosome 11 is a frequent target of lesions in myeloid malignancies. Therefore, we studied chromosome 11 in a total of 813 samples from 773 individual patients with different myeloid malignancies by SNP microarrays and complemented the data with exome sequencing in selected cases exhibiting chromosome 11 defects. We found gains, losses and UPDs of chromosome 11 in 52 of the 813 samples (6.4%. Chromosome 11q UPDs frequently associated with mutations of CBL. In one patient the 11qUPD amplified somatic mutations in both CBL and the DNA repair gene DDB1. A duplication within MLL exon 3 was detected in another patient with 11qUPD. We identified several common deleted regions (CDR on chromosome 11. One of the CDRs associated with de novo acute myeloid leukemia (P=0.013. One patient with a deletion at the LMO2 locus harbored an additional point mutation on the other allele indicating that LMO2 might be a tumor suppressor frequently targeted by 11p deletions. Our chromosome-centered analysis indicates that chromosome 11 contains a number of tumor suppressor genes and that the role of this chromosome in myeloid malignancies is more complex than previously recognized.

  19. A comparative physical map reveals the pattern of chromosomal evolution between the turkey (Meleagris gallopavo and chicken (Gallus gallus genomes

    Directory of Open Access Journals (Sweden)

    Delany Mary E

    2011-09-01

    Full Text Available Abstract Background A robust bacterial artificial chromosome (BAC-based physical map is essential for many aspects of genomics research, including an understanding of chromosome evolution, high-resolution genome mapping, marker-assisted breeding, positional cloning of genes, and quantitative trait analysis. To facilitate turkey genetics research and better understand avian genome evolution, a BAC-based integrated physical, genetic, and comparative map was developed for this important agricultural species. Results The turkey genome physical map was constructed based on 74,013 BAC fingerprints (11.9 × coverage from two independent libraries, and it was integrated with the turkey genetic map and chicken genome sequence using over 41,400 BAC assignments identified by 3,499 overgo hybridization probes along with > 43,000 BAC end sequences. The physical-comparative map consists of 74 BAC contigs, with an average contig size of 13.6 Mb. All but four of the turkey chromosomes were spanned on this map by three or fewer contigs, with 14 chromosomes spanned by a single contig and nine chromosomes spanned by two contigs. This map predicts 20 to 27 major rearrangements distinguishing turkey and chicken chromosomes, despite up to 40 million years of separate evolution between the two species. These data elucidate the chromosomal evolutionary pattern within the Phasianidae that led to the modern turkey and chicken karyotypes. The predominant rearrangement mode involves intra-chromosomal inversions, and there is a clear bias for these to result in centromere locations at or near telomeres in turkey chromosomes, in comparison to interstitial centromeres in the orthologous chicken chromosomes. Conclusion The BAC-based turkey-chicken comparative map provides novel insights into the evolution of avian genomes, a framework for assembly of turkey whole genome shotgun sequencing data, and tools for enhanced genetic improvement of these important agricultural and

  20. Patterns of replication in the neo-sex chromosomes of Drosophila nasuta albomicans

    Indian Academy of Sciences (India)

    G Mahesh; N B Ramachandra; H A Ranganath

    2000-09-01

    Drosophila nasuta albomicans (with 2n = 6), contains a pair of metacentric neo-sex chromosomes. Phylogenetically these are products of centric fusion between ancestral sex (X, Y) chromosomes and an autosome (chromosome 3). The polytene chromosome complement of males with a neo-X- and neo-Y-chromosomes has revealed asynchrony in replication between the two arms of the neo-sex chromosomes. The arm which represents the ancestral X-chromosome is faster replicating than the arm which represents ancestral autosome. The latter arm of the neo-sex chromosome is synchronous with other autosomes of the complement. We conclude that one arm of the neo-X/Y is still mimicking the features of an autosome while the other arm has the features of a classical X/Y-chromosome. This X-autosome translocation differs from the other evolutionary X-autosome translocations known in certain species of Drosophila.

  1. Structure, expression pattern and chromosomal localization of the rice Osgrp-2 gene

    Institute of Scientific and Technical Information of China (English)

    LIU; Zongzhi; (刘宗旨); WANG; Jianlong; (王建龙); WANG; Qun; (王群); HUANG; Xun; (黄勋); XU; Weihui; (徐卫辉); ZHU; Lihuang; (朱立煌); HE; Ping; (何平); FANG; Rongxiang; (方荣祥)

    2003-01-01

    Glycine-rich proteins (GRPs) belong to a kind of important structural proteins of plant cell walls. The expression of GRP genes is regulated spatially and developmentally as well as by various environmental stresses, thus providing a good model for the study of plant gene expression. We obtained the genomic sequence of a new GRP gene (Osgrp-2) from a rice genomic library. The transcription start site of Osgrp-2 was determined by 5'-rapid amplification of cDNA ends (RACE) and a 2.4-kb promoter sequence was thus delimited. The spatial and developmental expression pattern as well as the wound-inducible character of Osgrp-2 in rice plants was analyzed in detail. Furthermore, the gene was mapped onto rice chromosome 10 by analysis of restriction fragment length polymorphism (RFLP).

  2. The nucleotide excision repair (NER system of Helicobacter pylori: Role in mutation prevention and chromosomal import patterns after natural transformation

    Directory of Open Access Journals (Sweden)

    Moccia Claudia

    2012-05-01

    Full Text Available Abstract Background Extensive genetic diversity and rapid allelic diversification are characteristics of the human gastric pathogen Helicobacter pylori, and are believed to contribute to its ability to cause chronic infections. Both a high mutation rate and frequent imports of short fragments of exogenous DNA during mixed infections play important roles in generating this allelic diversity. In this study, we used a genetic approach to investigate the roles of nucleotide excision repair (NER pathway components in H. pylori mutation and recombination. Results Inactivation of any of the four uvr genes strongly increased the susceptibility of H. pylori to DNA damage by ultraviolet light. Inactivation of uvrA and uvrB significantly decreased mutation frequencies whereas only the uvrA deficient mutant exhibited a significant decrease of the recombination frequency after natural transformation. A uvrC mutant did not show significant changes in mutation or recombination rates; however, inactivation of uvrC promoted the incorporation of significantly longer fragments of donor DNA (2.2-fold increase into the recipient chromosome. A deletion of uvrD induced a hyper-recombinational phenotype. Conclusions Our data suggest that the NER system has multiple functions in the genetic diversification of H. pylori, by contributing to its high mutation rate, and by controlling the incorporation of imported DNA fragments after natural transformation.

  3. A neo-W chromosome in a tropical butterfly links colour pattern, male-killing, and speciation.

    Science.gov (United States)

    Smith, David A S; Gordon, Ian J; Traut, Walther; Herren, Jeremy; Collins, Steve; Martins, Dino J; Saitoti, Kennedy; Ireri, Piera; Ffrench-Constant, Richard

    2016-07-27

    Sexually antagonistic selection can drive both the evolution of sex chromosomes and speciation itself. The tropical butterfly the African Queen, Danaus chrysippus, shows two such sexually antagonistic phenotypes, the first being sex-linked colour pattern, the second, susceptibility to a male-killing, maternally inherited mollicute, Spiroplasma ixodeti, which causes approximately 100% mortality in male eggs and first instar larvae. Importantly, this mortality is not affected by the infection status of the male parent and the horizontal transmission of Spiroplasma is unknown. In East Africa, male-killing of the Queen is prevalent in a narrow hybrid zone centred on Nairobi. This hybrid zone separates otherwise allopatric subspecies with different colour patterns. Here we show that a neo-W chromosome, a fusion between the W (female) chromosome and an autosome that controls both colour pattern and male-killing, links the two phenotypes thereby driving speciation across the hybrid zone. Studies of the population genetics of the neo-W around Nairobi show that the interaction between colour pattern and male-killer susceptibility restricts gene flow between two subspecies of D. chrysippus Our results demonstrate how a complex interplay between sex, colour pattern, male-killing, and a neo-W chromosome, has set up a genetic 'sink' that keeps the two subspecies apart. The association between the neo-W and male-killing thus provides a 'smoking gun' for an ongoing speciation process.

  4. Patterns of association in the human metaphase complement: ring analysis and estimation of associativity of specific chromosome regions.

    Science.gov (United States)

    Rodman, T C; Flehinger, B J; Squire, R D

    1978-02-23

    The pattern of metaphase chromosome association in the human complement was studied by two methods of statistical analysis of interchromosomal distances. Those methods included ring analysis in which a characteristic position of the centromere of each chromosome relative to the center of a two dimensional representation of a metaphase complement was defined, and estimation of the capacity for associativity of each of three regions of each chromosome: the centromere (c) and the ends of each arm (p, q). The following information was obtained: 1. In general, the distance from the center is directly related to chromosome size. 2. The most notable deviation from that size-related progression is displayed by the X chromosomes. The markedly peripheral position of the X is characteristic of both X's of the female and the single X of the male. 3. The relative associativity of each chromosome of the complement is, in general, inversely related to size with an additional preferential capacity of associativity displayed by the acrocentric chromosomes. Analyses of the different inter-regional classes established that the supplementary associativity factor of the acrocentric chromosomes was inherent in their pericentromeric and p-arm regions and excluded the ends of the q arms from participation in that factor. 4. Those analyses demonstrated that the specific morphology or 'geometry' of the acrocentric chromosomes contributes little to their high relative associativity. In addition to the tendency for the c/p regions of the acrocentric chromosomes to associate with each other, presumably because of their common function in nucleolar organization, those regions also displayed a propensity to associate with the distal regions of the arms of other chromosomes. A molecular basis for that propensity other than that of ribosomal DNA is postulated to be that of other fractions of highly reiterated DNA sequences. 5. Analysis of the relative associativities of each of the three regions

  5. INCIDENCE OF DOWN’S SYNDROME WITH CHROMOSOMAL PATTERN IN THE EASTERN INDIA

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    Jami Sagar

    2014-07-01

    Full Text Available BACK GROUND: To study the chromosomal pattern of the Down’s syndrome patients of the eastern Indian population coming to the MKCG Medical College, Berhampur, Odisha, India. Methodology: 0.8ml of peripheral blood was collected from all the patients and cultured in RPMI 1640 medium for 72h in CO2 incubator. Then cells were harvested with colchicines and after the hypotonic treatment the slides were prepared and stained with giemsa. After that it was observed with high power microscope and reported. RESULT: From the 50 patients, 39 patients were Primary trisomy 21 (47, XX or XY+21, 6 was Mosaic Trisomy 21 (46/47, XX or XY+21, 3 was Down’s syndrome Primary amenorrohoea (47, XX, +21 and there was 2 translocation 46, XY, t (14:21 46, XY, t (21:21. The paternal age at 26-30 years were found more whereas the maternal age at 21-25 years was found more and males were more affected as compare to the females. CONCLUSION: It is tempting to speculate that, the difference in clinical features, growth retardation, abnormal dermatoglyphic patterns etc, are related to the genetic constitution of the Down’s syndrome individuals.

  6. High-resolution recombination patterns in a region of human chromosome 21 measured by sperm typing.

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    Irene Tiemann-Boege

    2006-05-01

    Full Text Available For decades, classical crossover studies and linkage disequilibrium (LD analysis of genomic regions suggested that human meiotic crossovers may not be randomly distributed along chromosomes but are focused instead in "hot spots." Recent sperm typing studies provided data at very high resolution and accuracy that defined the physical limits of a number of hot spots. The data were also used to test whether patterns of LD can predict hot spot locations. These sperm typing studies focused on several small regions of the genome already known or suspected of containing a hot spot based on the presence of LD breakdown or previous experimental evidence of hot spot activity. Comparable data on target regions not specifically chosen using these two criteria is lacking but is needed to make an unbiased test of whether LD data alone can accurately predict active hot spots. We used sperm typing to estimate recombination in 17 almost contiguous ~5 kb intervals spanning 103 kb of human Chromosome 21. We found two intervals that contained new hot spots. The comparison of our data with recombination rates predicted by statistical analyses of LD showed that, overall, the two datasets corresponded well, except for one predicted hot spot that showed little crossing over. This study doubles the experimental data on recombination in men at the highest resolution and accuracy and supports the emerging genome-wide picture that recombination is localized in small regions separated by cold areas. Detailed study of one of the new hot spots revealed a sperm donor with a decrease in recombination intensity at the canonical recombination site but an increase in crossover activity nearby. This unique finding suggests that the position and intensity of hot spots may evolve by means of a concerted mechanism that maintains the overall recombination intensity in the region.

  7. An uncommon H3/Ser10 phosphorylation pattern in Cestrum strigilatum (Solanaceae), a species with B chromosomes.

    Science.gov (United States)

    Fernandes, Thiago; Yuyama, Priscila Mary; Moraes, Ana Paula; Vanzela, André Luís Laforga

    2008-09-01

    Cestrum strigilatum (Solanaceae) is a South American shrub with B chromosomes. Bs show a univalent behavior when a single B is present, have non-Mendelian segregation, and are poor in genes and rich in repetitive DNA. In this study, the histone H3 at serine 10 (H3/Ser10) phosphorylation pattern was investigated during mitosis and meiosis of C. strigilatum collected from the wild and was compared in A and B chromosomes. The results revealed that H3/Ser10 phosphorylation of A chromosomes occurred only in the pericentromeric region in both mitosis and meiosis, whereas in the B univalent, phosphorylation appeared in almost the whole extent of the chromosome, except in the terminal portion of the long arm. In meiosis II, the phosphorylation of A chromosomes was similar to that in the first division of meiosis, but the Bs did not show H3/Ser10 phosphorylation. Our results suggest that phosphorylation at the pericentromeric region may be associated with chromosome motility during cell divisions and with the cohesion of B chromatids in a univalent structure in meiosis I.

  8. Adjusting breast cancer patient prognosis with non-HER2-gene patterns on chromosome 17.

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    Vassiliki Kotoula

    Full Text Available BACKGROUND: HER2 and TOP2A gene status are assessed for diagnostic and research purposes in breast cancer with fluorescence in situ hybridization (FISH. However, FISH probes do not target only the annotated gene, while chromosome 17 (chr17 is among the most unstable chromosomes in breast cancer. Here we asked whether the status of specifically targeted genes on chr17 might help in refining prognosis of early high-risk breast cancer patients. METHODS: Copy numbers (CN for 14 genes on chr17, 4 of which were within and 10 outside the core HER2 amplicon (HER2- and non-HER2-genes, respectively were assessed with qPCR in 485 paraffin-embedded tumor tissue samples from breast cancer patients treated with adjuvant chemotherapy in the frame of two randomized phase III trials. PRINCIPAL FINDINGS: HER2-genes CN strongly correlated to each other (Spearman's rho >0.6 and were concordant with FISH HER2 status (Kappa 0.6697 for ERBB2 CN. TOP2A CN were not concordant with TOP2A FISH status (Kappa 0.1154. CN hierarchical clustering revealed distinct patterns of gains, losses and complex alterations in HER2- and non-HER2-genes associated with IHC4 breast cancer subtypes. Upon multivariate analysis, non-HER2-gene gains independently predicted for shorter disease-free survival (DFS and overall survival (OS in patients with triple-negative cancer, as compared to luminal and HER2-positive tumors (interaction p = 0.007 for DFS and p = 0.011 for OS. Similarly, non-HER2-gene gains were associated with worse prognosis in patients who had undergone breast-conserving surgery as compared to modified radical mastectomy (p = 0.004 for both DFS and OS. Non-HER2-gene losses were unfavorable prognosticators in patients with 1-3 metastatic nodes, as compared to those with 4 or more nodes (p = 0.017 for DFS and p = 0.001 for OS. CONCLUSIONS: TOP2A FISH and qPCR may not identify the same pathology on chr17q. Non-HER2 chr17 CN patterns may further predict outcome in breast cancer

  9. X inactivation in females with X-linked Charcot-Marie-Tooth disease.

    LENUS (Irish Health Repository)

    Murphy, Sinéad M

    2012-07-01

    X-linked Charcot-Marie-Tooth disease (CMT1X) is the second most common inherited neuropathy, caused by mutations in gap junction beta-1 (GJB1). Males have a uniformly moderately severe phenotype while females have a variable phenotype, suggested to be due to X inactivation. We aimed to assess X inactivation pattern in females with CMT1X and correlate this with phenotype using the CMT examination score to determine whether the X inactivation pattern accounted for the variable phenotype in females with CMT1X. We determined X inactivation pattern in 67 females with CMT1X and 24 controls using the androgen receptor assay. We were able to determine which X chromosome carried the GJB1 mutation in 30 females. There was no difference in X inactivation pattern between patients and controls. In addition, there was no correlation between X inactivation pattern in blood and phenotype. A possible explanation for these findings is that the X inactivation pattern in Schwann cells rather than in blood may explain the variable phenotype in females with CMT1X.

  10. Exploring Codon Usage Patterns of Alternatively Spliced Genes in Human Chromosome 1

    Institute of Scientific and Technical Information of China (English)

    马飞; 庄永龙; 黄颖; 李衍达

    2004-01-01

    In this study, 414 whole protein-coding sequences (238 004 codons) of alternatively spliced genes of human chromosome 1 have been employed to explore the patterns of codon usage bias among genes. Overall codon usage data analysis indicates that G- and C-ending codons are predominant in the genes. The base usage in all three codon positions suggests a selection-mutation balance. Multivariate statistical analysis reveals that the codon usage variation has a strong positive correlation with the expressivities of the genes (r=0.5790, P<0.0001). All 27 codons identified as optimal are G- and C-ending codons.Correlation analysis shows a strong negative correlation between the gene length and codon adaptation index value (r=-0.2252, P<0.0001), and a significantly positive correlation between the gene length and Nc values (r=0.1876, P<0.0001). These results suggest that the comparatively shorter genes in the genes have higher codon usage bias to maximize translational efficiency, and selection may also contribute to the reduction of highly expressed proteins.

  11. Early embryonic chromosome instability results in stable mosaic pattern in human tissues.

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    Hasmik Mkrtchyan

    Full Text Available The discovery of copy number variations (CNV in the human genome opened new perspectives on the study of the genetic causes of inherited disorders and the aetiology of common diseases. Here, a single-cell-level investigation of CNV in different human tissues led us to uncover the phenomenon of mitotically derived genomic mosaicism, which is stable in different cell types of one individual. The CNV mosaic ratios were different between the 10 individuals studied. However, they were stable in the T lymphocytes, immortalized B lymphoblastoid cells, and skin fibroblasts analyzed in each individual. Because these cell types have a common origin in the connective tissues, we suggest that mitotic changes in CNV regions may happen early during embryonic development and occur only once, after which the stable mosaic ratio is maintained throughout the differentiated tissues. This concept is further supported by a unique study of immortalized B lymphoblastoid cell lines obtained with 20 year difference from two subjects. We provide the first evidence of somatic mosaicism for CNV, with stable variation ratios in different cell types of one individual leading to the hypothesis of early embryonic chromosome instability resulting in stable mosaic pattern in human tissues. This concept has the potential to open new perspectives in personalized genetic diagnostics and can explain genetic phenomena like diminished penetrance in autosomal dominant diseases. We propose that further genomic studies should focus on the single-cell level, to better understand the aetiology of aging and diseases mediated by somatic mutations.

  12. The Differences Between Cis- and Trans-Gene Inactivation Caused by Heterochromatin in Drosophila.

    Science.gov (United States)

    Abramov, Yuriy A; Shatskikh, Aleksei S; Maksimenko, Oksana G; Bonaccorsi, Silvia; Gvozdev, Vladimir A; Lavrov, Sergey A

    2016-01-01

    Position-effect variegation (PEV) is the epigenetic disruption of gene expression near the de novo-formed euchromatin-heterochromatin border. Heterochromatic cis-inactivation may be accompanied by the trans-inactivation of genes on a normal homologous chromosome in trans-heterozygous combination with a PEV-inducing rearrangement. We characterize a new genetic system, inversion In(2)A4, demonstrating cis-acting PEV as well as trans-inactivation of the reporter transgenes on the homologous nonrearranged chromosome. The cis-effect of heterochromatin in the inversion results not only in repression but also in activation of genes, and it varies at different developmental stages. While cis-actions affect only a few juxtaposed genes, trans-inactivation is observed in a 500-kb region and demonstrates а nonuniform pattern of repression with intermingled regions where no transgene repression occurs. There is no repression around the histone gene cluster and in some other euchromatic sites. trans-Inactivation is accompanied by dragging of euchromatic regions into the heterochromatic compartment, but the histone gene cluster, located in the middle of the trans-inactivated region, was shown to be evicted from the heterochromatin. We demonstrate that trans-inactivation is followed by de novo HP1a accumulation in the affected transgene; trans-inactivation is specifically favored by the chromatin remodeler SAYP and prevented by Argonaute AGO2.

  13. Patterns of rDNA chromosomal localization in Palearctic Cephalota and Cylindera (Coleoptera: Carabidae: Cicindelini with different numbers of X-chromosomes

    Directory of Open Access Journals (Sweden)

    Sonia J. R. Proença

    2011-05-01

    Full Text Available The ribosomal clusters of six Paleartic taxa belonging to the tiger beetle genera Cephalota Dokhtourow, 1883 and Cylindera Westwood, 1831, with multiple sex chromosomes (XXY, XXXY and XXXXY have been localised on mitotic and meiotic cells by fluorescence in situ hybridization (FISH, using a PCR-amplified 18S rDNA fragment as a probe. Four patterns of rDNA localization in these tiger beetles were found: 1. Two clusters located in one autosomal pair; 2. Two clusters located in one autosomal pair and one in an X chromosome; 3. Three clusters located in three heterosomes (XXY; 4. Two clusters located in one autosomal pair and two in the heterosomes (one of the Xs and the Y. These results illustrate that ribosomal cistrons have changed their number and localization during the evolution of these genera, showing a dynamic rather than a conservative pattern. These changes in rDNA localization are uncoupled with changes in the number of autosomes and/or heterosomes. A mechanism that involves transposable elements that carry ribosomal cistrons appears to be the most plausible explanation for these dynamics that involve jumping from one location in the genome to another, in some cases leaving copies in the original location.

  14. Distinct nuclear orientation patterns for mouse chromosome 11 in normal B lymphocytes

    NARCIS (Netherlands)

    Schmälter, A.K.; Kuzyk, A.; Righolt, C.H.; Neusser, M.; Steinlein, O.K.; Müller, S.; Mai, S.

    2014-01-01

    Background Characterizing the nuclear orientation of chromosomes in the three-dimensional (3D) nucleus by multicolor banding (mBANDing) is a new approach towards understanding nuclear organization of chromosome territories. An mBANDing paint is composed of multiple overlapping subchromosomal probes

  15. Divergence between C. melo and African Cucumis Species Identified by Chromosome Painting and rDNA Distribution Pattern.

    Science.gov (United States)

    Li, Kunpeng; Wang, Huaisong; Wang, Jiming; Sun, Jianying; Li, Zongyun; Han, Yonghua

    2016-01-01

    The 5S and 45S rDNA sites are useful chromosome landmarks and can provide valuable information about karyotype evolution and species interrelationships. In this study, we employed fluorescence in situ hybridization (FISH) to determine the number and chromosomal location of 5S and 45S rDNA loci in 8 diploid Cucumis species. Two oligonucleotide painting probes specific for the rDNA-bearing chromosomes in C. melo were hybridized to other Cucumis species in order to investigate the homeologies among the rDNA-carrying chromosomes in Cucumis species. The analyzed diploid species showed 3 types of rDNA distribution patterns, which provided clear cytogenetic evidence on the divergence between C. melo and wild diploid African Cucumis species. The present results not only show species interrelationships in the genus Cucumis, but the rDNA FISH patterns can also be used as cytological markers for the discrimination of closely related species. The data will be helpful for breeders to choose the most suitable species from various wild species for improvement of cultivated melon.

  16. Preliminary evidence of a noncausal association between the X-chromosome inactivation pattern and thyroid autoimmunity: a twin study

    DEFF Research Database (Denmark)

    Brix, Thomas Heiberg; Hansen, Pia Skov; Kyvik, Kirsten Ohm;

    2009-01-01

    the impact of XCI on the serum concentration of TPOAb, we studied whether within-cohort and within-twin-pair differences in XCI are associated with differences in serum concentrations of TPOAb. A total of 318 euthyroid female twin individuals distributed in 159 pairs were investigated. XCI was determined...... was significant in the 77 dizygotic pairs (beta=2.17 (0.81-3.53), P=0.002). This preliminary finding of a significant association between TPOAb concentrations and XCI within cohort and within dizygotic but not within monozygotic twin pairs may indicate that XCI per se does not have a major role...

  17. Chromosomal instability in meningiomas.

    Science.gov (United States)

    van Tilborg, Angela A G; Al Allak, Bushra; Velthuizen, Sandra C J M; de Vries, Annie; Kros, Johan M; Avezaat, Cees J J; de Klein, Annelies; Beverloo, H Berna; Zwarthoff, Ellen C

    2005-04-01

    Approximately 60% of sporadic meningiomas are caused by inactivation of the NF2 tumor suppressor gene on chromosome 22. No causative gene is known for the remaining 40%. Cytogenetic analysis shows that meningiomas caused by inactivation of the NF2 gene can be divided into tumors that show monosomy 22 as the sole abnormality and tumors with a more complex karyotype. Meningiomas not caused by the NF2 gene usually have a diploid karyotype. Here we report that, besides the clonal chromosomal aberrations, the chromosome numbers in many meningiomas varied from one metaphase spread to the other, a feature that is indicative of chromosomal instability. Unexpectedly and regardless of genotype, a subgroup of tumors was observed with an average number of 44.9 chromosomes and little variation in the number of chromosomes per metaphase spread. In addition, a second subgroup was recognized with a hyperdiploid number of chromosomes (average 48.5) and considerable variation in numbers per metaphase. However, this numerical instability resulted in a clonal karyotype with chromosomal gains and losses in addition to loss of chromosome 22 only in meningiomas caused by inactivation of the NF2 gene. In cultured cells of all tumor groups, bi- and multinucleated cells were seen, as well as anaphase bridges, residual chromatid strings, multiple spindle poles, and unseparated chromatids, suggesting defects in the mitotic apparatus or kinetochore. Thus, we conclude that even a benign and slow-growing tumor like a meningioma displays chromosomal instability.

  18. Homomorphic sex chromosomes and the intriguing Y chromosome of Ctenomys rodent species (Rodentia, Ctenomyidae).

    Science.gov (United States)

    Suárez-Villota, Elkin Y; Pansonato-Alves, José C; Foresti, Fausto; Gallardo, Milton H

    2014-01-01

    Unlike the X chromosome, the mammalian Y chromosome undergoes evolutionary decay resulting in small size. This sex chromosomal heteromorphism, observed in most species of the fossorial rodent Ctenomys, contrasts with the medium-sized, homomorphic acrocentric sex chromosomes of closely related C. maulinus and C. sp. To characterize the sequence composition of these chromosomes, fluorescent banding, self-genomic in situ hybridization, and fluorescent in situ hybridization with an X painting probe were performed on mitotic and meiotic plates. High molecular homology between the sex chromosomes was detected on mitotic material as well as on meiotic plates immunodetected with anti-SYCP3 and anti-γH2AX. The Y chromosome is euchromatic, poor in repetitive sequences and differs from the X by the loss of a block of pericentromeric chromatin. Inferred from the G-banding pattern, an inversion and the concomitant prevention of recombination in a large asynaptic region seems to be crucial for meiotic X chromosome inactivation. These peculiar findings together with the homomorphism of Ctenomys sex chromosomes are discussed in the light of the regular purge that counteracts Muller's ratchet and the probable mechanisms accounting for their origin and molecular homology.

  19. Patterns of recombination activity on mouse chromosome 11 revealed by high resolution mapping.

    Directory of Open Access Journals (Sweden)

    Timothy Billings

    Full Text Available The success of high resolution genetic mapping of disease predisposition and quantitative trait loci in humans and experimental animals depends on the positions of key crossover events around the gene of interest. In mammals, the majority of recombination occurs at highly delimited 1-2 kb long sites known as recombination hotspots, whose locations and activities are distributed unevenly along the chromosomes and are tightly regulated in a sex specific manner. The factors determining the location of hotspots started to emerge with the finding of PRDM9 as a major hotspot regulator in mammals, however, additional factors modulating hotspot activity and sex specificity are yet to be defined. To address this limitation, we have collected and mapped the locations of 4829 crossover events occurring on mouse chromosome 11 in 5858 meioses of male and female reciprocal F1 hybrids of C57BL/6J and CAST/EiJ mice. This chromosome was chosen for its medium size and high gene density and provided a comparison with our previous analysis of recombination on the longest mouse chromosome 1. Crossovers were mapped to an average resolution of 127 kb, and thirteen hotspots were mapped to <8 kb. Most crossovers occurred in a small number of the most active hotspots. Females had higher recombination rate than males as a consequence of differences in crossover interference and regional variation of sex specific rates along the chromosome. Comparison with chromosome 1 showed that recombination events tend to be positioned in similar fashion along the centromere-telomere axis but independently of the local gene density. It appears that mammalian recombination is regulated on at least three levels, chromosome-wide, regional, and at individual hotspots, and these regulation levels are influenced by sex and genetic background but not by gene content.

  20. A recurrent pattern of chromosomal aberrations and immunophenotypic appearance defines anal squamous cell carcinomas.

    Science.gov (United States)

    Heselmeyer, K; du Manoir, S; Blegen, H; Friberg, B; Svensson, C; Schröck, E; Veldman, T; Shah, K; Auer, G; Ried, T

    1997-01-01

    Squamous cell carcinomas of the anus are rare neoplasias that account for about 3% of large bowel tumours. Infections with human papillomaviruses are frequently detected in these cancers, suggesting that pathogenic pathways in anal carcinomas and in carcinomas of the uterine cervix are similar. Little is known regarding recurrent chromosomal aberrations in this subgroup of squamous cell carcinomas. We have applied comparative genomic hybridization to identify chromosomal gains and losses in 23 cases of anal carcinomas. A non-random copy number increase of chromosomes 17 and 19, and chromosome arm 3q was observed. Consistent losses were mapped to chromosome arms 4p, 11q, 13q and 18q. A majority of the tumours were aneuploid, and most of them showed increased proliferative activity as determined by staining for Ki-67 antigen. p53 expression was low or undetectable, and expression of p21/WAF-1 was increased in most tumours. Sixteen cancers were satisfactorily tested for the presence of HPV by consensus L1-primer polymerase chain reaction; nine were HPV positive, of which eight were positive for HPV 16.

  1. Trehalose and sorbitol alter the kinetic pattern of inactivation of glutamate dehydrogenase during drying in levitated microdroplets.

    Science.gov (United States)

    Lorenzen, Elke; Lee, Geoffrey

    2013-12-01

    A single-droplet acoustic levitator was used to determine the drying rate and the kinetics of inactivation of glutamate dehydrogenase in the presence of added trehalose or sorbitol. The solution was also spray dried under the same process condition of drying gas temperature on a bench-top machine. Both trehalose and sorbitol delay the point of onset of enzyme inactivation which lies after the critical point of drying. Both carbohydrates also reduce the apparent rate constant of inactivation calculated during the subsequent inactivation phase. The carbohydrates stabilise, therefore, the enzyme during droplet drying and particle formation mainly during the falling rate drying period. There is no difference between the stabilising effects of the two carbohydrates when examined as levitated single droplets. This suggests the importance of water replacement as a stabilising mechanism in the levitated droplets/particles. On spray drying, the trehalose stabilises the enzyme better than does the sorbitol at a drying gas (outlet) temperature of 60°C. This suggests glass formation with the trehalose but not the sorbitol during the very rapid drying process of small-atomised droplets in the spray dryer.

  2. Patterns of Y-chromosome diversity intersect with the Trans-New Guinea hypothesis.

    Science.gov (United States)

    Mona, Stefano; Tommaseo-Ponzetta, Mila; Brauer, Silke; Sudoyo, Herawati; Marzuki, Sangkot; Kayser, Manfred

    2007-11-01

    The island of New Guinea received part of the first human expansion out of Africa (>40,000 years ago), but its human genetic history remains poorly understood. In this study, we examined Y-chromosome diversity in 162 samples from the Bird's Head region of northwest New Guinea (NWNG) and compared the results with previously obtained data from other parts of the island. NWNG harbors a high level of cultural and linguistic diversity and is inhabited by non-Austronesian (i.e., Papuan)-speaking groups as well as harboring most of West New Guinea's (WNG) Austronesian-speaking groups. However, 97.5% of its Y-chromosomes belong to 5 haplogroups that originated in Melanesia; hence, the Y-chromosome diversity of NWNG (and, according to available data, of New Guinea as a whole) essentially reflects a local history. The remaining 2.5% belong to 2 haplogroups (O-M119 and O-M122) of East Asian origin, which were brought to New Guinea by Austronesian-speaking migrants around 3,500 years ago. Thus, the Austronesian expansion had only a small impact on shaping Y-chromosome diversity in NWNG, although the linguistic impact of this expansion to this region was much higher. In contrast, the expansion of Trans-New Guinea (TNG) speakers (non-Austronesian) starting about 6,000-10,000 years ago from the central highlands of what is now Papua New Guinea, presumably in combination with the expansion of agriculture, played a more important role in determining the Y-chromosome diversity of New Guinea. In particular, we identified 2 haplogroups (M-P34 and K-M254) as suggestive markers for the TNG expansion, whereas 2 other haplogroups (C-M38 and K-M9) most likely reflect the earlier local Y-chromosome diversity. We propose that sex-biased differences in the social structure and cultural heritage of the people involved in the Austronesian and the TNG expansions played an important role (among other factors) in shaping the New Guinean Y-chromosome landscape.

  3. Contrasting patterns of Y chromosome and mtDNA variation in Africa: evidence for sex-biased demographic processes.

    Science.gov (United States)

    Wood, Elizabeth T; Stover, Daryn A; Ehret, Christopher; Destro-Bisol, Giovanni; Spedini, Gabriella; McLeod, Howard; Louie, Leslie; Bamshad, Mike; Strassmann, Beverly I; Soodyall, Himla; Hammer, Michael F

    2005-07-01

    To investigate associations between genetic, linguistic, and geographic variation in Africa, we type 50 Y chromosome SNPs in 1122 individuals from 40 populations representing African geographic and linguistic diversity. We compare these patterns of variation with those that emerge from a similar analysis of published mtDNA HVS1 sequences from 1918 individuals from 39 African populations. For the Y chromosome, Mantel tests reveal a strong partial correlation between genetic and linguistic distances (r=0.33, P=0.001) and no correlation between genetic and geographic distances (r=-0.08, P>0.10). In contrast, mtDNA variation is weakly correlated with both language (r=0.16, P=0.046) and geography (r=0.17, P=0.035). AMOVA indicates that the amount of paternal among-group variation is much higher when populations are grouped by linguistics (Phi(CT)=0.21) than by geography (Phi(CT)=0.06). Levels of maternal genetic among-group variation are low for both linguistics and geography (Phi(CT)=0.03 and 0.04, respectively). When Bantu speakers are removed from these analyses, the correlation with linguistic variation disappears for the Y chromosome and strengthens for mtDNA. These data suggest that patterns of differentiation and gene flow in Africa have differed for men and women in the recent evolutionary past. We infer that sex-biased rates of admixture and/or language borrowing between expanding Bantu farmers and local hunter-gatherers played an important role in influencing patterns of genetic variation during the spread of African agriculture in the last 4000 years.

  4. Inter-chromosomal variation in the pattern of human population genetic structure

    Directory of Open Access Journals (Sweden)

    Baye Tesfaye M

    2011-05-01

    Full Text Available Abstract Emerging technologies now make it possible to genotype hundreds of thousands of genetic variations in individuals, across the genome. The study of loci at finer scales will facilitate the understanding of genetic variation at genomic and geographic levels. We examined global and chromosomal variations across HapMap populations using 3.7 million single nucleotide polymorphisms to search for the most stratified genomic regions of human populations and linked these regions to ontological annotation and functional network analysis. To achieve this, we used five complementary statistical and genetic network procedures: principal component (PC, cluster, discriminant, fixation index (FST and network/pathway analyses. At the global level, the first two PC scores were sufficient to account for major population structure; however, chromosomal level analysis detected subtle forms of population structure within continental populations, and as many as 31 PCs were required to classify individuals into homogeneous groups. Using recommended population ancestry differentiation measures, a total of 126 regions of the genome were catalogued. Gene ontology and networks analyses revealed that these regions included the genes encoding oculocutaneous albinism II (OCA2, hect domain and RLD 2 (HERC2, ectodysplasin A receptor (EDAR and solute carrier family 45, member 2 (SLC45A2. These genes are associated with melanin production, which is involved in the development of skin and hair colour, skin cancer and eye pigmentation. We also identified the genes encoding interferon-γ (IFNG and death-associated protein kinase 1 (DAPK1, which are associated with cell death, inflammatory and immunological diseases. An in-depth understanding of these genomic regions may help to explain variations in adaptation to different environments. Our approach offers a comprehensive strategy for analysing chromosome-based population structure and differentiation, and demonstrates the

  5. Complex high-resolution linkage disequilibrium and haplotype patterns of single-nucleotide polymorphisms in 2.5 Mb of sequence on human chromosome 21.

    Science.gov (United States)

    Olivier, M; Bustos, V I; Levy, M R; Smick, G A; Moreno, I; Bushard, J M; Almendras, A A; Sheppard, K; Zierten, D L; Aggarwal, A; Carlson, C S; Foster, B D; Vo, N; Kelly, L; Liu, X; Cox, D R

    2001-11-01

    One approach to identify potentially important segments of the human genome is to search for DNA regions with nonrandom patterns of human sequence variation. Previous studies have investigated these patterns primarily in and around candidate gene regions. Here, we determined patterns of DNA sequence variation in 2.5 Mb of finished sequence from five regions on human chromosome 21. By sequencing 13 individual chromosomes, we identified 1460 single-nucleotide polymorphisms (SNPs) and obtained unambiguous haplotypes for all chromosomes. For all five chromosomal regions, we observed segments with high linkage disequilibrium (LD), extending from 1.7 to>81 kb (average 21.7 kb), disrupted by segments of similar or larger size with no significant LD between SNPs. At least 25% of the contig sequences consisted of segments with high LD between SNPs. Each of these segments was characterized by a restricted number of observed haplotypes,with the major haplotype found in over 60% of all chromosomes. In contrast, the interspersed segments with low LD showed significantly more haplotype patterns. The position and extent of the segments of high LD with restricted haplotype variability did not coincide with the location of coding sequences. Our results indicate that LD and haplotype patterns need to be investigated with closely spaced SNPs throughout the human genome, independent of the location of coding sequences, to reliably identify regions with significant LD useful for disease association studies.

  6. Genetic admixture, relatedness, and structure patterns among Mexican populations revealed by the Y-chromosome.

    Science.gov (United States)

    Rangel-Villalobos, H; Muñoz-Valle, J F; González-Martín, A; Gorostiza, A; Magaña, M T; Páez-Riberos, L A

    2008-04-01

    Y-linked markers are suitable loci to analyze genetic diversity of human populations, offering knowledge of medical, forensic, and anthropological interest. In a population sample of 206 Mestizo males from western Mexico, we analyzed two binary loci (M3 and YAP) and six Y-STRs, adding to the analysis data of Mexican Mestizos and Amerindians, and relevant worldwide populations. The paternal ancestry estimated in western Mexican-Mestizos was mainly European (60-64%), followed by Amerindian (25-21%), and African ( approximately 15%). Significant genetic heterogeneity was established between Mestizos from western (Jalisco State) and northern Mexico (Chihuahua State) compared with Mexicans from the center of the Mexican Republic (Mexico City), this attributable to higher European ancestry in western and northern than in central and southeast populations, where higher Amerindian ancestry was inferred. This genetic structure has important implications for medical and forensic purposes. Two different Pre-Hispanic evolutionary processes were evident. In Mesoamerican region, populations presented higher migration rate (N(m) = 24.76), promoting genetic homogeneity. Conversely, isolated groups from the mountains and canyons of the Western and Northern Sierra Madre (Huichols and Tarahumaras, respectively) presented a lower migration rate (N(m) = 10.27) and stronger genetic differentiation processes (founder effect and/or genetic drift), constituting a Pre-Hispanic population substructure. Additionally, Tarahumaras presented a higher frequency of Y-chromosomes without Q3 that was explained by paternal European admixture (15%) and, more interestingly, by a distinctive Native-American ancestry. In Purepechas, a special admixture process involving preferential integration of non-Purepecha women in their communities could explain contrary genetic evidences (autosomal vs. Y-chromosome) for this tribe.

  7. Cloning, tissue expression pattern, and chromosome localization of human protein kinase Bγ gene

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Protein kinase B (PKB) is a member of the second messenger-regulated subfamily of protein kinases, and plays a key role in cell-cycle regulation, glucose uptake and promotion of cell differentiation. Evidence shows that PKB undergoes activation in some human tumors and is involved in Ras pathway, which implies that PKB can trigger a pathway to induce oncogenic transformation. A nucleotide sequence of mouse Pkb? was used as a probe to screen homolog in a human liver cDNA library. A fragment of 1998 bp containing a 1440 bp ORF encoding 479 amino acid residues was obtained. Then the 3'-terminal of this fragment was extended to 2788 bp by 'electronic walking' screening, and the extended fragment was confirmed by PCR amplification. The protein deduced by the gene had a high identity of 83% and 78% to the human PKBγ and γ, respectively, and was designated as human PKB?. Northern hybridization detected two equally expressed transcripts of 8.5 and 6.5 kb in length in all 16 human tissues tested, with the highest expression level in brain, and lower levels with variation in the other tissues. By RH mapping, the PKBγ was placed on chromosome 1q43, between markers D1S304 and D1S2693. It is a valuable clue for cloning the candidate genes related to prostate cancer; Arrhythmogenic Right Ventricular Dysplasia (ARVD); Chediak-Higashi, NK cell Deficiency (CHS); and Hypoparathyrodism with Short Stature, Mental Retardation and Seizures which have already been mapped in this chromosomal region.

  8. Mating patterns amongst Siberian reindeer herders: inferences from mtDNA and Y-chromosomal analyses.

    Science.gov (United States)

    Pakendorf, Brigitte; Novgorodov, Innokentij N; Osakovskij, Vladimir L; Stoneking, Mark

    2007-07-01

    The Evenks and Evens, who speak closely related languages belonging to the Northern Tungusic branch of the Tungusic family, are nomadic reindeer herders and hunters. They are spread over an immense territory in northeastern Siberia, and consequently different subgroups are in contact with diverse peoples speaking Samoyedic, Turkic, Mongolic, Chukotka-Kamchatkan, and Yukaghir languages. Nevertheless, the languages and culture of the Evenks and Evens are similar enough for them to have been classified as a single ethnic group in the past. This linguistic and cultural similarity indicates that they may have spread over their current area of habitation relatively recently, and thus may be closely related genetically. On the other hand, the great distances that separate individual groups of Evens and Evenks from each other might have led to preferential mating with geographic neighbors rather than with linguistically related peoples. In this study, we assess the correlation between linguistic and genetic relationship in three different subgroups of Evenks and Evens, respectively, via mtDNA and Y-chromosomal analyses. The results show that there is some evidence of a common origin based on shared mtDNA lineages and relatively similar Y-haplogroup frequencies amongst most of the Evenk and Even subgroups. However, there is little sharing of Y-chromosomal STR haplotypes, indicating that males within Evenk and Even subgroups have remained relatively isolated. There is further evidence of some female admixture in different Even subgroups with their respective geographic neighbors. However, the Tungusic groups, and especially the Evenks, show signs of genetic drift, making inferences about their prehistory difficult.

  9. X-inactivation patterns in female Leber`s hereditary optic neuropathy patients do not support a strong X-linked determinant

    Energy Technology Data Exchange (ETDEWEB)

    Pegoraro, E.; Hoffman, E.P. [Univ. of Pittsburgh School of Medicine, PA (United States); Carelli, V.; Cortelli, P. [Univ. of Bologna (Italy)] [and others

    1996-02-02

    Leber`s hereditary optic neuropathy (LHON) accounts for about 3% of the cases of blindness in young adult males. The underlying mitochondrial pathogenesis of LHON has been well studied, with specific mitochondrial DNA (mtDNA) mutations of structural genes described and well characterized. However, enigmatic aspects of the disease are not explained by mutation data, such as the higher proportion of affected males, the later onset of the disease in females, and the presence of unaffected individuals with a high proportion of mutant mtDNA. A hypothesis which has been put forward to explain the unusual disease expression is a dual model of mtDNA and X-linked nuclear gene inheritance. If a nuclear X-linked modifier gene influences the expression of the mitochondrial-linked mutant gene then the affected females should be either homozygous for the nuclear determinant, or if heterozygous, lyonization should favor the mutant X. In order to determine if an X-linked gene predisposes to LHON phenotype we studied X-inactivation patterns in 35 females with known mtDNA mutations from 10 LHON pedigrees. Our results do not support a strong X-linked determinant in LHON cause: 2 of the 10 (20%) manifesting carriers showed skewing of X-inactivation, as did 3 of the 25 (12%) nonmanifesting carriers. 39 refs., 2 figs., 1 tab.

  10. [Sex chromosomes and meiosis].

    Science.gov (United States)

    Guichaoua, M-R; Geoffroy-Siraudin, C; Tassistro, V; Ghalamoun-Slaimi, R; Perrin, J; Metzler-Guillemain, C

    2009-01-01

    Sex chromosome behaviour fundamentally differs between male and female meiosis. In oocyte, X chromosomes synapse giving a XX bivalent which is not recognizable in their morphology and behaviour from autosomal bivalents. In human male, X and Y chromosomes differ from one another in their morphology and their genetic content, leading to a limited pairing and preventing genetic recombination, excepted in homologous region PAR1. During pachytene stage of the first meiotic prophase, X and Y chromosomes undergo a progressive condensation and form a transcriptionally silenced peripheral XY body. The condensation of the XY bivalent during pachytene stage led us to describe four pachytene substages and to localize the pachytene checkpoint between substages 2 and 3. We also defined the pachytene index (PI=P1+P2/P1+P2+P3+P4) which is always less than 0.50 in normal meiosis. XY body undergoes decondensation at diplotene stage, but transcriptional inactivation of the two sex chromosomes or Meiotic Sex Chromosome Inactivation (MSCI) persists through to the end of spermatogenesis. Sex chromosome inactivation involves several proteins, some of them were now identified. Two isoforms of the HP1 protein, HP1beta and HP1gamma, are involved in the facultative heterochromatinization of the XY body, but the initiation of this process involves the phosphorylation of the protein H2AX by the kinase ATR whose recruitment depends on BRCA1. Extensive researches on the inactivation of the sex chromosomes during male meiosis will allow to a better understanding of some male infertilities.

  11. Mesenchymal stem cells with high telomerase expression do not actively restore their chromosome arm specific telomere length pattern after exposure to ionizing radiation

    DEFF Research Database (Denmark)

    Graakjaer, Jesper; Christensen, Rikke; Kolvraa, Steen;

    2007-01-01

    BACKGROUND: Previous studies have demonstrated that telomeres in somatic cells are not randomly distributed at the end of the chromosomes. We hypothesize that these chromosome arm specific differences in telomere length (the telomere length pattern) may be actively maintained. In this study we...... investigate the existence and maintenance of the telomere length pattern in stem cells. For this aim we studied telomere length in primary human mesenchymal stem cells (hMSC) and their telomerase-immortalised counterpart (hMSC-telo1) during extended proliferation as well as after irradiation. Telomere lengths...... were measured using Fluorescence In Situ Hybridization (Q-FISH). RESULTS: A telomere length pattern was found to exist in primary hMSC's as well as in hMSC-telo1. This pattern is similar to what was previously found in lymphocytes and fibroblasts. The cells were then exposed to a high dose of ionizing...

  12. Physical maps and recombination frequency of six rice chromosomes.

    Science.gov (United States)

    Wu, Jianzhong; Mizuno, Hiroshi; Hayashi-Tsugane, Mika; Ito, Yukiyo; Chiden, Yoshino; Fujisawa, Masaki; Katagiri, Satoshi; Saji, Shoko; Yoshiki, Shoji; Karasawa, Wataru; Yoshihara, Rie; Hayashi, Akiko; Kobayashi, Harumi; Ito, Kazue; Hamada, Masao; Okamoto, Masako; Ikeno, Maiko; Ichikawa, Yoko; Katayose, Yuichi; Yano, Masahiro; Matsumoto, Takashi; Sasaki, Takuji

    2003-12-01

    We constructed physical maps of rice chromosomes 1, 2, and 6-9 with P1-derived artificial chromosome (PAC) and bacterial artificial chromosome (BAC) clones. These maps, with only 20 gaps, cover more than 97% of the predicted length of the six chromosomes. We submitted a total of 193 Mbp of non-overlapping sequences to public databases. We analyzed the DNA sequences of 1316 genetic markers and six centromere-specific repeats to facilitate characterization of chromosomal recombination frequency and of the genomic composition and structure of the centromeric regions. We found marked changes in the relative recombination rate along the length of each chromosome. Chromosomal recombination at the centromere core and surrounding regions on the six chromosomes was completely suppressed. These regions have a total physical length of about 23 Mbp, corresponding to 11.4% of the entire size of the six chromosomes. Chromosome 6 has the longest quiescent region, with about 5.6 Mbp, followed by chromosome 8, with quiescent region about half this size. Repetitive sequences accounted for at least 40% of the total genomic sequence on the partly sequenced centromeric region of chromosome 1. Rice CentO satellite DNA is arrayed in clusters and is closely associated with the presence of Centromeric Retrotransposon of Rice (CRR)- and RIce RetroElement 7 (RIRE7)-like retroelement sequences. We also detected relatively small coldspot regions outside the centromeric region; their repetitive content and gene density were similar to those of regions with normal recombination rates. Sequence analysis of these regions suggests that either the amount or the organization patterns of repetitive sequences may play a role in the inactivation of recombination.

  13. Orc1 Binding to Mitotic Chromosomes Precedes Spatial Patterning during G1 Phase and Assembly of the Origin Recognition Complex in Human Cells.

    Science.gov (United States)

    Kara, Nihan; Hossain, Manzar; Prasanth, Supriya G; Stillman, Bruce

    2015-05-08

    Replication of eukaryotic chromosomes occurs once every cell division cycle in normal cells and is a tightly controlled process that ensures complete genome duplication. The origin recognition complex (ORC) plays a key role during the initiation of DNA replication. In human cells, the level of Orc1, the largest subunit of ORC, is regulated during the cell division cycle, and thus ORC is a dynamic complex. Upon S phase entry, Orc1 is ubiquitinated and targeted for destruction, with subsequent dissociation of ORC from chromosomes. Time lapse and live cell images of human cells expressing fluorescently tagged Orc1 show that Orc1 re-localizes to condensing chromatin during early mitosis and then displays different nuclear localization patterns at different times during G1 phase, remaining associated with late replicating regions of the genome in late G1 phase. The initial binding of Orc1 to mitotic chromosomes requires C-terminal amino acid sequences that are similar to mitotic chromosome-binding sequences in the transcriptional pioneer protein FOXA1. Depletion of Orc1 causes concomitant loss of the mini-chromosome maintenance (Mcm2-7) helicase proteins on chromatin. The data suggest that Orc1 acts as a nucleating center for ORC assembly and then pre-replication complex assembly by binding to mitotic chromosomes, followed by gradual removal from chromatin during the G1 phase.

  14. Chromosomal redistribution of male-biased genes in mammalian evolution with two bursts of gene gain on the X chromosome.

    Science.gov (United States)

    Zhang, Yong E; Vibranovski, Maria D; Landback, Patrick; Marais, Gabriel A B; Long, Manyuan

    2010-10-05

    Mammalian X chromosomes evolved under various mechanisms including sexual antagonism, the faster-X process, and meiotic sex chromosome inactivation (MSCI). These forces may contribute to nonrandom chromosomal distribution of sex-biased genes. In order to understand the evolution of gene content on the X chromosome and autosome under these forces, we dated human and mouse protein-coding genes and miRNA genes on the vertebrate phylogenetic tree. We found that the X chromosome recently acquired a burst of young male-biased genes, which is consistent with fixation of recessive male-beneficial alleles by sexual antagonism. For genes originating earlier, however, this pattern diminishes and finally reverses with an overrepresentation of the oldest male-biased genes on autosomes. MSCI contributes to this dynamic since it silences X-linked old genes but not X-linked young genes. This demasculinization process seems to be associated with feminization of the X chromosome with more X-linked old genes expressed in ovaries. Moreover, we detected another burst of gene originations after the split of eutherian mammals and opossum, and these genes were quickly incorporated into transcriptional networks of multiple tissues. Preexisting X-linked genes also show significantly higher protein-level evolution during this period compared to autosomal genes, suggesting positive selection accompanied the early evolution of mammalian X chromosomes. These two findings cast new light on the evolutionary history of the mammalian X chromosome in terms of gene gain, sequence, and expressional evolution.

  15. Chromosomal redistribution of male-biased genes in mammalian evolution with two bursts of gene gain on the X chromosome.

    Directory of Open Access Journals (Sweden)

    Yong E Zhang

    Full Text Available Mammalian X chromosomes evolved under various mechanisms including sexual antagonism, the faster-X process, and meiotic sex chromosome inactivation (MSCI. These forces may contribute to nonrandom chromosomal distribution of sex-biased genes. In order to understand the evolution of gene content on the X chromosome and autosome under these forces, we dated human and mouse protein-coding genes and miRNA genes on the vertebrate phylogenetic tree. We found that the X chromosome recently acquired a burst of young male-biased genes, which is consistent with fixation of recessive male-beneficial alleles by sexual antagonism. For genes originating earlier, however, this pattern diminishes and finally reverses with an overrepresentation of the oldest male-biased genes on autosomes. MSCI contributes to this dynamic since it silences X-linked old genes but not X-linked young genes. This demasculinization process seems to be associated with feminization of the X chromosome with more X-linked old genes expressed in ovaries. Moreover, we detected another burst of gene originations after the split of eutherian mammals and opossum, and these genes were quickly incorporated into transcriptional networks of multiple tissues. Preexisting X-linked genes also show significantly higher protein-level evolution during this period compared to autosomal genes, suggesting positive selection accompanied the early evolution of mammalian X chromosomes. These two findings cast new light on the evolutionary history of the mammalian X chromosome in terms of gene gain, sequence, and expressional evolution.

  16. Normal X-inactivation mosaicism in corneas of heterozygous FlnaDilp2/+ female mice--a model of human Filamin A (FLNA diseases

    Directory of Open Access Journals (Sweden)

    Douvaras Panagiotis

    2012-02-01

    Full Text Available Abstract Background Some abnormalities of mouse corneal epithelial maintenance can be identified by the atypical mosaic patterns they produce in X-chromosome inactivation mosaics and chimeras. Human FLNA/+ females, heterozygous for X-linked, filamin A gene (FLNA mutations, display a range of disorders and X-inactivation mosaicism is sometimes quantitatively unbalanced. FlnaDilp2/+ mice, heterozygous for an X-linked filamin A (Flna nonsense mutation have variable eye, skeletal and other abnormalities, but X-inactivation mosaicism has not been investigated. The aim of this study was to determine whether X-inactivation mosaicism in the corneal epithelia of FlnaDilp2/+ mice was affected in any way that might predict abnormal corneal epithelial maintenance. Results X-chromosome inactivation mosaicism was studied in the corneal epithelium and a control tissue (liver of FlnaDilp2/+ and wild-type (WT female X-inactivation mosaics, hemizygous for the X-linked, LacZ reporter H253 transgene, using β-galactosidase histochemical staining. The corneal epithelia of FlnaDilp2/+ and WT X-inactivation mosaics showed similar radial, striped patterns, implying epithelial cell movement was not disrupted in FlnaDilp2/+ corneas. Corrected stripe numbers declined with age overall (but not significantly for either genotype individually, consistent with previous reports suggesting an age-related reduction in stem cell function. Corrected stripe numbers were not reduced in FlnaDilp2/+ compared with WT X-inactivation mosaics and mosaicism was not significantly more unbalanced in the corneal epithelia or livers of FlnaDilp2/+ than wild-type Flna+/+ X-inactivation mosaics. Conclusions Mosaic analysis identified no major effect of the mouse FlnaDilp2 mutation on corneal epithelial maintenance or the balance of X-inactivation mosaicism in the corneal epithelium or liver.

  17. Notes on chromosome numbers and C-banding patterns in karyotypes of some weevils from central Europe (Coleoptera, Curculionoidea: Apionidae, Nanophyidae, Curculionidae).

    Science.gov (United States)

    Lachowska, Dorota; Holecová, Milada; Rozek, Maria

    2004-01-01

    Chromosome numbers and C-banding patterns of sixteen weevil species are presented. The obtained results confirm the existence of two groups of species with either a small or large amount of heterochromatin in the karyotype. The first group comprises twelve species (Apionidae: Oxystoma cerdo, Eutrichapion melancholicum, Ceratapion penetrans, Ceratapion austriacum, Squamapion flavimanum, Rhopalapion longirostre; Nanophyidae: Nanophyes marmoratus; Curculionidae: Centricnemus (=Peritelus) leucogrammus, Sitona humeralis, Sitona lineatus, Sitona macularis, Sitona suturalis). In weevils with a small amount of heterochromatin, tiny grains on the nucleus during interphase are visible, afterwards appearing as dark dots during mitotic and meiotic prophase. The second group comprises four species from the curculionid subfamily Cryptorhynchinae (Acalles camelus, Acalles commutatus, Acalles echinatus, Ruteria hypocrita) which possess much larger heteropycnotic chromosome parts visible during all nuclear divisions. The species examined have pericentromeric C-bands on autosomes and on the X chromosome.

  18. Levels and patterns of nucleotide variation in domestication QTL regions on rice chromosome 3 suggest lineage-specific selection.

    Directory of Open Access Journals (Sweden)

    Xianfa Xie

    Full Text Available Oryza sativa or Asian cultivated rice is one of the major cereal grass species domesticated for human food use during the Neolithic. Domestication of this species from the wild grass Oryza rufipogon was accompanied by changes in several traits, including seed shattering, percent seed set, tillering, grain weight, and flowering time. Quantitative trait locus (QTL mapping has identified three genomic regions in chromosome 3 that appear to be associated with these traits. We would like to study whether these regions show signatures of selection and whether the same genetic basis underlies the domestication of different rice varieties. Fragments of 88 genes spanning these three genomic regions were sequenced from multiple accessions of two major varietal groups in O. sativa--indica and tropical japonica--as well as the ancestral wild rice species O. rufipogon. In tropical japonica, the levels of nucleotide variation in these three QTL regions are significantly lower compared to genome-wide levels, and coalescent simulations based on a complex demographic model of rice domestication indicate that these patterns are consistent with selection. In contrast, there is no significant reduction in nucleotide diversity in the homologous regions in indica rice. These results suggest that there are differences in the genetic and selective basis for domestication between these two Asian rice varietal groups.

  19. Xist RNA is confined to the nuclear territory of the silenced X chromosome throughout the cell cycle

    NARCIS (Netherlands)

    Jonkers, Iris; Monkhorst, Kim; Rentmeester, Eveline; Grootegoed, J Anton; Grosveld, Frank; Gribnau, Joost

    2008-01-01

    In mammalian female cells, one X chromosome is inactivated to prevent a dose difference in the expression of X-encoded proteins between males and females. Xist RNA, required for X chromosome inactivation, is transcribed from the future inactivated X chromosome (Xi), where it spreads in cis, to initi

  20. Inactivated vaccine with adjuvants consisting of pattern recognition receptor agonists confers protection against avian influenza viruses in chickens.

    Science.gov (United States)

    Tang, Yinghua; Lu, Jihu; Wu, Peipei; Liu, Zhenxing; Tian, Zhen; Zha, Guofei; Chen, Hui; Wang, Qiaochu; Wang, Qiaoxiu; Hou, Fengxiang; Kang, Sang-Moo; Hou, Jibo

    2014-08-01

    Use of adjuvant containing pathogen pattern recognition receptor agonists is one of the effective strategies to enhance the efficacy of licensed vaccines. In this study, we investigated the efficacy of avian influenza vaccines containing an adjuvant (CVCVA5) which was composed of polyriboinosinic polyribocytidylic, resiquimod, imiquimod, muramyl dipeptide and levomisole. Avian influenza vaccines adjuvanted with CVCVA5 were found to induce significantly higher titers of hemagglutiniton inhibition antibodies (P≤0.01) than those of commercial vaccines at 2-, 3- and 4-week post vaccination in both specific pathogen free (SPF) chickens and field application. Furthermore, virus shedding was reduced in SPF chickens immunized with H9-CVCVA5 vaccine after H9 subtype heterologous virus challenge. The ratios of both CD3(+)CD4(+) and CD3(+)CD8(+) lymphocytes were slowly elevated in chickens immunized with H9-CVCVA5 vaccine. Lymphocytes adoptive transfer study indicates that CD8(+) T lymphocyte subpopulation might have contributed to improved protection against heterologous virus challenge. Results of this study suggest that the adjuvant CVCVA5 was capable of enhancing the potency of existing avian influenza vaccines by increasing humoral and cellular immune response.

  1. Cloning, tissue expression pattern characterization and chromosome localization of human peptide methionine sulfoxide reductase cDNA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Oxidation and reduction of some amino acids are one of the molecular mechanisms for regulating the function of proteins. The oxidation of methionine (Met) to methionine sulfoxide (Met(O)) results in decreasing or loss of the biological activity of related proteins. It was found that peptide methionine sulfoxide reductase (msrA) can reduce Met(O) to Met and therefore restored the biological function of the oxidized proteins. To reveal the methionine oxidation-reduction mechanism in human body, in this study, the cDNA sequence of bovine msrA was used as an information-probe to screen the human EST database. Based on a contig assembled from homologous ESTs, a 1 256-bp human MSRA cDNA was cloned from several human cDNA libraries. The cDNA contains an open reading frame (ORF) of 705 bp in length, which encodes 235 amino acid residues. Homology comparison revealed that human MSRA shares 88% and 61% identities with bovine and Escherichia coli msrA protein respectively. Expression pattern analysis revealed a single 1.6-kb transcript of human MSRA in most human tissues and with highest expression in kidney. By radiation hybrid panel mapping, the gene was localized to human chromosome 8p22-23 between markers D8S518 and D8S550. There are 2 human inherited diseases Keratolytic Winter Erythema and Microcephaly related genes in this region, it is inferred that human MSRA might be the candidate of the two diseases.

  2. Function of the sex chromosomes in mammalian fertility.

    Science.gov (United States)

    Heard, Edith; Turner, James

    2011-10-01

    The sex chromosomes play a highly specialized role in germ cell development in mammals, being enriched in genes expressed in the testis and ovary. Sex chromosome abnormalities (e.g., Klinefelter [XXY] and Turner [XO] syndrome) constitute the largest class of chromosome abnormalities and the commonest genetic cause of infertility in humans. Understanding how sex-gene expression is regulated is therefore critical to our understanding of human reproduction. Here, we describe how the expression of sex-linked genes varies during germ cell development; in females, the inactive X chromosome is reactivated before meiosis, whereas in males the X and Y chromosomes are inactivated at this stage. We discuss the epigenetics of sex chromosome inactivation and how this process has influenced the gene content of the mammalian X and Y chromosomes. We also present working models for how perturbations in sex chromosome inactivation or reactivation result in subfertility in the major classes of sex chromosome abnormalities.

  3. A comparison of the chromosome G-banding pattern in two Sorex species, S. satunini and S. araneus (Mammalia, Insectivora

    Directory of Open Access Journals (Sweden)

    Yuri Borisov

    2012-08-01

    Full Text Available The G-banded karyotype of S. satunini was compared with the karyotype of Sorex araneus. Extensive homology was revealed. The major chromosomal rearrangements involved in the evolutionary divergence of these species have been identified as centric fusions and centromeric shifts. From the known palaeontological age of S. satunini it is obvious that the vast chromosomal polymorphism of the S. araneus group originated during the middle Pleistocene.

  4. A case of 48, XXYY syndrome with diabetes and the analysis of the parental origin of X chromosome and skewed X-inactivation%48,XXYY综合征合并糖尿病1例的X染色体来源和失活偏移分析

    Institute of Scientific and Technical Information of China (English)

    潘清蓉; 茅江峰; 范慧; 姚志; 徐援

    2013-01-01

    目的 初步探讨48,XXYY综合征合并糖尿病患者的临床特点,并分析该疾病的X染色体来源和失活偏移.方法收集患者的临床资料,抽提患者及其父母的外周血基因组DNA,应用PCR结合HpaⅡ限制性内切酶消化法分析X染色体来源和失活偏移.结果 患者临床表现及实验室检查完全符合48,XXYY综合征,使用二甲双胍和睾酮治疗后患者血糖控制平稳.患者X染色体分别来源于父亲和母亲,两条X染色体均为部分失活,偏移度为0.52.结论 48,XXYY综合征合并糖尿病的发病机制可能与睾酮水平低下、胰岛素抵抗有关.48,XXYY综合征多余X染色体来源于父亲,X染色体不一定存在失活偏移.%Objective To explore the clinical features of 48,XXYY syndrome with diabetices; to analyze parental origin of X-chromosome and skewed X-inactivation.Methods Genomic DNA was extracted from peripheral blood sample.The parental origin of X chromosome and skewed X-inactivation were analyzed using PCR combined Hpa Ⅱ restriction enzyme digestion.Results The patient was diagnosed as 48,XXYY syndrome with diabetes according to the clinical presentations and laboratory examinations.Plasma glucose level remained stable after metformin plus testosterone treatment.The X chromosome were inherited from the patient' father and mother.The degree of skew of X-inactivation was 0.52.Conclusions The pathogenesis of diabetes in 48,XXYY patient may be associated with low testosterone levels and insulin resistance.The extra X chromosome of our case and others have reported eight cases of 48,XXYY syndrome were paternal origin.Not all of 48,XXYY syndrome patients had skew X-inactivation.

  5. Analysis of ATP7A Gene in Patients with Menkes Disease and X Chromosome Inactivation in a Case with Menkes Disease%Menkes病患儿ATP7A基因突变及X染色体失活分析

    Institute of Scientific and Technical Information of China (English)

    赵程峰; 王静敏; 王菊莉; 黄琼辉; 邓艳华; 吴晔; 姜玉武

    2013-01-01

    Objective:To analyze and characterize the genetic features of a chinese family with Menkes disease. Familial cases of Menkes disease are rare and are due to X-chromosomal inheritance fron a carrier mother. To explain the pathogenic mechanism of the sex-limited expression of Menkes disease, we have analyzed the parental origin of mutations and the XCL status in cases with Menkes disease due to ATP7A molecular defects. Methods: Genomic DNAs from the patient and her parents were extracted using standard procedures from the peripheral blood leukocytes, PCR and DNA direct sequencing were employed to analyze all of the 7 exons of the DCX gene to determine the gene mutation. The degree of XCL and its direction relative to the X chromosome parent of origin were measured in DNA prepared from peripheral blood leucocytes by analyzing CAG repeat polymorphism in the androgen receptor gene (AR). Results:PCR detected a deletion of c.3045delT(p.T1016fsX1018),while her mother was a carrier for the mutation. The cases had a skewed XCL pattern and he favor expression of the maternal origin allele. Conclusion:The proband carried a deletion c.3045delT(p.T1016fsX1018),and his mother is normal, consistent with recessive inheritance. The skewed XCL pattern was the main XCL pattern in Menkes disease patients. The priority inactive X chromosome was mainly of maternal origin.%  目的:分析并确立1例Menkes病的ATP7A基因突变,并从X染色体失活角度探讨突变的亲源性和ATP7A的致病机制。方法:首先搜集该例临床典型Menkes病患儿及其父母的外周血提取基因组DNA,分别对患儿及父母的外周血DNA进行PCR扩增,通过DNA测序和琼脂糖凝胶电泳判定患儿突变的亲源性;用雄激素受体基因(AR)的三核苷酸多态性进行基因型分析判定X染色体失活是否发生偏斜。结果:基因诊断确诊1例Menkes病患儿,DNA直接测序检测结果为c.3045delT(p.T1016fsX1018)缺失突变,其母亲

  6. Chromosome Connections: Compelling Clues to Common Ancestry

    Science.gov (United States)

    Flammer, Larry

    2013-01-01

    Students compare banding patterns on hominid chromosomes and see striking evidence of their common ancestry. To test this, human chromosome no. 2 is matched with two shorter chimpanzee chromosomes, leading to the hypothesis that human chromosome 2 resulted from the fusion of the two shorter chromosomes. Students test that hypothesis by looking for…

  7. Genomic insights into hybridization in a localized region of sympatr y between pewee sister species (Contopus sordidulus × C. virens) and their chromosomal patterns of differentiation

    Institute of Scientific and Technical Information of China (English)

    Joseph D Manthey; and Mark B Robbins

    2016-01-01

    Background: The Great Plains of the United States includes a large number of hybrid and contact zones between bird species. The amount of gene lfow between sister species in these zones ranges from very rare hybridization events to widespread and prevalent introgression. Some of these avian systems have been studied extensively, while others have been indeterminate of whether hybridization exists in areas of sympatry. Using genomic-level approaches allows investigation of genomic patterns of hybridization and gene lfow between species—or lack thereof. Methods: We investigated a narrow zone of sympatry in Nebraska, USA between pewee species (Contopus sordidu-lus and C. virens), for which no hybridization has been conifrmed. We used thousands of single nucleotide polymor-phisms to identify potential hybridization and investigate genomic patterns of differentiation between these two species. Results: We found evidence of multiple hybrid individuals in the contact zone. Little genomic variation was ifxed between species, but a large proportion had differentiated allele frequencies between species. There was a positive relationship between genetic differentiation and chromosome size. Conclusions: We provided the ifrst conclusive evidence of hybridization between C. sordidulus and C. virens, in a region where secondary contact likely occurred due to human disturbance and habitat modiifcation. The genomic patterns of differentiation affrm that these species split in the relatively recent past. Finally, the relationship of chro-mosome size and genetic differentiation may have resulted from differential rates of chromosomal recombination in songbirds and genetic differentiation between species largely due to genetic drift (possibly in concert with selection).

  8. X chromosome regulation of autosomal gene expression in bovine blastocysts

    OpenAIRE

    Itoh, Yuichiro; Arnold, Arthur P.

    2014-01-01

    Although X chromosome inactivation in female mammals evolved to balance the expression of X chromosome and autosomal genes in the two sexes, female embryos pass through developmental stages in which both X chromosomes are active in somatic cells. Bovine blastocysts show higher expression of many X genes in XX than XY embryos, suggesting that X inactivation is not complete. Here we reanalyzed bovine blastocyst microarray expression data from a network perspective with a focus on interactions b...

  9. Genetic characterization in symptomatic female DMD carriers: lack of relationship between X-inactivation, transcriptional DMD allele balancing and phenotype

    Directory of Open Access Journals (Sweden)

    Brioschi Simona

    2012-08-01

    Full Text Available Abstract Background Although Duchenne and Becker muscular dystrophies, X-linked recessive myopathies, predominantly affect males, a clinically significant proportion of females manifesting symptoms have also been reported. They represent an heterogeneous group characterized by variable degrees of muscle weakness and/or cardiac involvement. Though preferential inactivation of the normal X chromosome has long been considered the principal mechanism behind disease manifestation in these females, supporting evidence is controversial. Methods Eighteen females showing a mosaic pattern of dystrophin expression on muscle biopsy were recruited and classified as symptomatic (7 or asymptomatic (11, based on the presence or absence of muscle weakness. The causative DMD gene mutations were identified in all cases, and the X-inactivation pattern was assessed in muscle DNA. Transcriptional analysis in muscles was performed in all females, and relative quantification of wild-type and mutated transcripts was also performed in 9 carriers. Dystrophin protein was quantified by immunoblotting in 2 females. Results The study highlighted a lack of relationship between dystrophic phenotype and X-inactivation pattern in females; skewed X-inactivation was found in 2 out of 6 symptomatic carriers and in 5 out of 11 asymptomatic carriers. All females were characterized by biallelic transcription, but no association was found between X-inactivation pattern and allele transcriptional balancing. Either a prevalence of wild-type transcript or equal proportions of wild-type and mutated RNAs was observed in both symptomatic and asymptomatic females. Moreover, very similar levels of total and wild-type transcripts were identified in the two groups of carriers. Conclusions This is the first study deeply exploring the DMD transcriptional behaviour in a cohort of female carriers. Notably, no relationship between X-inactivation pattern and transcriptional behaviour of DMD gene was

  10. "Chromosome": a knowledge-based system for the chromosome classification.

    Science.gov (United States)

    Ramstein, G; Bernadet, M

    1993-01-01

    Chromosome, a knowledge-based analysis system has been designed for the classification of human chromosomes. Its aim is to perform an optimal classification by driving a tool box containing the procedures of image processing, pattern recognition and classification. This paper presents the general architecture of Chromosome, based on a multiagent system generator. The image processing tool box is described from the met aphasic enhancement to the fine classification. Emphasis is then put on the knowledge base intended for the chromosome recognition. The global classification process is also presented, showing how Chromosome proceeds to classify a given chromosome. Finally, we discuss further extensions of the system for the karyotype building.

  11. Structural organization of the inactive X chromosome in the mouse.

    Science.gov (United States)

    Giorgetti, Luca; Lajoie, Bryan R; Carter, Ava C; Attia, Mikael; Zhan, Ye; Xu, Jin; Chen, Chong Jian; Kaplan, Noam; Chang, Howard Y; Heard, Edith; Dekker, Job

    2016-07-28

    X-chromosome inactivation (XCI) involves major reorganization of the X chromosome as it becomes silent and heterochromatic. During female mammalian development, XCI is triggered by upregulation of the non-coding Xist RNA from one of the two X chromosomes. Xist coats the chromosome in cis and induces silencing of almost all genes via its A-repeat region, although some genes (constitutive escapees) avoid silencing in most cell types, and others (facultative escapees) escape XCI only in specific contexts. A role for Xist in organizing the inactive X (Xi) chromosome has been proposed. Recent chromosome conformation capture approaches have revealed global loss of local structure on the Xi chromosome and formation of large mega-domains, separated by a region containing the DXZ4 macrosatellite. However, the molecular architecture of the Xi chromosome, in both the silent and expressed regions,remains unclear. Here we investigate the structure, chromatin accessibility and expression status of the mouse Xi chromosome in highly polymorphic clonal neural progenitors (NPCs) and embryonic stem cells. We demonstrate a crucial role for Xist and the DXZ4-containing boundary in shaping Xi chromosome structure using allele-specific genome-wide chromosome conformation capture (Hi-C) analysis, an assay for transposase-accessible chromatin with high throughput sequencing (ATAC-seq) and RNA sequencing. Deletion of the boundary disrupts mega-domain formation, and induction of Xist RNA initiates formation of the boundary and the loss of DNA accessibility. We also show that in NPCs, the Xi chromosome lacks active/inactive compartments and topologically associating domains (TADs), except around genes that escape XCI. Escapee gene clusters display TAD-like structures and retain DNA accessibility at promoter-proximal and CTCF-binding sites. Furthermore, altered patterns of facultative escape genes indifferent neural progenitor clones are associated with the presence of different TAD

  12. Correlation of chromosome patterns in human leukemic cells with exposure to chemicals and/or radiation. Progress report, July 1992--August 1993

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, J.D.

    1993-09-01

    Progress in identification of chromosomal transformations associated with leukemogenesis is described. In particular progress in DNA cloning of chromosomal break points in human cancer patients is described.

  13. X-inactivation and X-reactivation: epigenetic hallmarks of mammalian reproduction and pluripotent stem cells.

    Science.gov (United States)

    Payer, Bernhard; Lee, Jeannie T; Namekawa, Satoshi H

    2011-08-01

    X-chromosome inactivation is an epigenetic hallmark of mammalian development. Chromosome-wide regulation of the X-chromosome is essential in embryonic and germ cell development. In the male germline, the X-chromosome goes through meiotic sex chromosome inactivation, and the chromosome-wide silencing is maintained from meiosis into spermatids before the transmission to female embryos. In early female mouse embryos, X-inactivation is imprinted to occur on the paternal X-chromosome, representing the epigenetic programs acquired in both parental germlines. Recent advances revealed that the inactive X-chromosome in both females and males can be dissected into two elements: repeat elements versus unique coding genes. The inactive paternal X in female preimplantation embryos is reactivated in the inner cell mass of blastocysts in order to subsequently allow the random form of X-inactivation in the female embryo, by which both Xs have an equal chance of being inactivated. X-chromosome reactivation is regulated by pluripotency factors and also occurs in early female germ cells and in pluripotent stem cells, where X-reactivation is a stringent marker of naive ground state pluripotency. Here we summarize recent progress in the study of X-inactivation and X-reactivation during mammalian reproduction and development as well as in pluripotent stem cells.

  14. Plasticity in the Meiotic Epigenetic Landscape of Sex Chromosomes in Caenorhabditis Species.

    Science.gov (United States)

    Larson, Braden J; Van, Mike V; Nakayama, Taylor; Engebrecht, JoAnne

    2016-08-01

    During meiosis in the heterogametic sex in some species, sex chromosomes undergo meiotic sex chromosome inactivation (MSCI), which results in acquisition of repressive chromatin and transcriptional silencing. In Caenorhabditis elegans, MSCI is mediated by MET-2 methyltransferase deposition of histone H3 lysine 9 dimethylation. Here we examined the meiotic chromatin landscape in germ lines of four Caenorhabditis species; C. remanei and C. brenneri represent ancestral gonochorism, while C. briggsae and C. elegans are two lineages that independently evolved hermaphroditism. While MSCI is conserved across all four species, repressive chromatin modifications are distinct and do not correlate with reproductive mode. In contrast to C. elegans and C. remanei germ cells where X chromosomes are enriched for histone H3 lysine 9 dimethylation, X chromosomes in C. briggsae and C. brenneri germ cells are enriched for histone H3 lysine 9 trimethylation. Inactivation of C. briggsae MET-2 resulted in germ-line X chromosome transcription and checkpoint activation. Further, both histone H3 lysine 9 di- and trimethylation were reduced in Cbr-met-2 mutant germ lines, suggesting that in contrast to C. elegans, H3 lysine 9 di- and trimethylation are interdependent. C. briggsae H3 lysine 9 trimethylation was redistributed in the presence of asynapsed chromosomes in a sex-specific manner in the related process of meiotic silencing of unsynapsed chromatin. However, these repressive marks did not influence X chromosome replication timing. Examination of additional Caenorhabditis species revealed diverse H3 lysine 9 methylation patterns on the X, suggesting that the sex chromosome epigenome evolves rapidly.

  15. Correlation of chromosome patterns in leukemic cells of patients with exposure to chemicals and/or radiation

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, J.D.

    1989-10-01

    We have identified two new recurring translocations involving chromosome 5; one is a 3;5 translocation and the other involves a rearrangement between chromosomes 5 and 7. The first is t(3;5)(q25.1;q35). We studied five patients with AML and a t(3;5) in their leukemic cells. At diagnosis, four of the patients had a t(3;5) as their sole karyotypic anomaly; the remaining patient had additional structural and numerical abnormalities. Careful cytogenetic analysis indicated that the breakpoints of this rearrangement were 3q25.1 and 5q34, in contrast to the various breakpoints reported in earlier studies (3q21 to 3q25 and 5q31 to 5q35). The karyotypic, morphologic, and clinical characteristics of this group, as well as those of 15 previously reported patients with the t(3;5), were compared to identify any features that might warrant consideration of this anomaly as a specific syndrome. The median age of the group, 37 years, as younger than that of all patients with AML, 49 years. A preceding myelodysplastic syndrome was observed in three patients. We have no information regarding the occupation of most of these patients. Except for acute promyelocytic leukemia, each morphologic subtype occurred in these patients; however, the frequency of erythroleukemia (M6) was much greater than expected. 11 refs., 2 figs., 5 tabs.

  16. Marker chromosomes.

    Science.gov (United States)

    Rao, Kiran Prabhaker; Belogolovkin, Victoria

    2013-04-01

    Marker chromosomes are a morphologically heterogeneous group of structurally abnormal chromosomes that pose a significant challenge in prenatal diagnosis. Phenotypes associated with marker chromosomes are highly variable and range from normal to severely abnormal. Clinical outcomes are very difficult to predict when marker chromosomes are detected prenatally. In this review, we outline the classification, etiology, cytogenetic characterization, and clinical consequences of marker chromosomes, as well as practical approaches to prenatal diagnosis and genetic counseling.

  17. Neocentric X-chromosome in a girl with Turner-like syndrome

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    Hemmat Morteza

    2012-06-01

    Full Text Available Abstract Background Neocentromeres are rare human chromosomal aberrations in which a new centromere has formed in a previously non-centromeric location. We report the finding of a structurally abnormal X chromosome with a neocentromere in a 15-year-old girl with clinical features suggestive of Turner syndrome, including short stature and primary amenorrhea. Result G-banded chromosome analysis revealed a mosaic female karyotype involving two abnormal cell lines. One cell line (84% of analyzed metaphases had a structurally abnormal X chromosome (duplication of the long arm and deletion of the short arm and a normal X chromosome. The other cell line (16% of cells exhibited monosomy X. C-banding studies were negative for the abnormal X chromosome. FISH analysis revealed lack of hybridization of the abnormal X chromosome with both the X centromere-specific probe and the “all human centromeres” probe, a pattern consistent with lack of the X chromosome endogenous centromere. A FISH study using an XIST gene probe revealed the presence of two XIST genes, one on each long arm of the iso(Xq, required for inactivation of the abnormal X chromosome. R-banding also demonstrated inactivation of the abnormal X chromosome. An assay for centromeric protein C (CENP-C was positive on both the normal and the abnormal X chromosomes. The position of CENP-C in the abnormal X chromosome defined a neocentromere, which explains its mitotic stability. The karyotype is thus designated as 46,X,neo(X(qter- > q12::q12- > q21.2- > neo- > q21.2- > qter[42]/45,X[8], which is consistent with stigmata of Turner syndrome. The mother of this patient has a normal karyotype; however, the father was not available for study. Conclusion To our knowledge, this is the first case of mosaic Turner syndrome involving an analphoid iso(Xq chromosome with a proven neocentromere among 90 previously described cases with a proven neocentromere.

  18. Physical mapping and YAC contig analysis of the region surrounding Xist on the mouse X chromosome.

    Science.gov (United States)

    Heard, E; Simmler, M C; Larin, Z; Rougeulle, C; Courtier, B; Lehrach, H; Avner, P

    1993-03-01

    The Xist sequence has been proposed as a potential candidate for the X-inactivation center based both on its localization within the candidate region for the X-inactivation center in man and mouse and on its unique pattern of expression from the inactive X chromosome. We have cloned 550 kb of DNA surrounding the mouse Xist sequence in contiguously overlapping YAC clones and have developed a long-range restriction map that spans almost 1 Mb of this region and includes this YAC contig. The detailed restriction map we have established provides a framework for the identification of expressed sequences other than Xist that may equally exhibit unusual expression characteristics associated with X inactivation. The presence of possible structural or methylation differences within this region between the active and inactive X chromosomes has been investigated through comparative analysis of male and female genomic DNA, and we report here the identification of certain CpG-containing restriction sites around Xist that have an interesting differential methylation status on the inactive and active X chromosomes.

  19. X Inactivation and Progenitor Cancer Cells

    Directory of Open Access Journals (Sweden)

    Ruben Agrelo

    2011-04-01

    Full Text Available In mammals, silencing of one of the two X chromosomes is necessary to achieve dosage compensation. The 17 kb non-coding RNA called Xist triggers X inactivation. Gene silencing by Xist can only be achieved in certain contexts such as in cells of the early embryo and in certain hematopoietic progenitors where silencing factors are present. Moreover, these epigenetic contexts are maintained in cancer progenitors in which SATB1 has been identified as a factor related to Xist-mediated chromosome silencing.

  20. Genetic control of X inactivation and processes leading to X-inactivation skewing

    Energy Technology Data Exchange (ETDEWEB)

    Belmont, J.W. [Baylor College of Medicine, Houston, TX (United States)

    1996-06-01

    The chromosomal basis of sex determination (i.e., XX in females, XY in males) results in an inequality of gene copy number and content between males and females. In humans (and other mammals) the potential imbalance of gene expression from the two X chromosomes in females is resolved by inactivating one X in all the somatic tissues. Beginning in the late blastocyst stage of embryonic development, one of the two X chromosomes is globally down-regulated in each somatic cell, resulting in expression from only one allele at the vast majority of X-encoded loci. While the paternal X is selectively inactive in the extraembryonic tissues (vide infra), in the embryo proper the process of X inactivation is random between the maternal and paternal X chromosomes. The result is that most females have mosaic expression of maternal and paternal alleles of X chromosome loci. The mean contribution from each chromosome is 50%, but because the process is generally random, a normal female may vary considerably from the mean. 67 refs., 1 fig.

  1. Heteromorphic sex chromosomes: navigating meiosis without a homologous partner.

    Science.gov (United States)

    Checchi, Paula M; Engebrecht, Joanne

    2011-09-01

    Accurate chromosome segregation during meiosis relies on homology between the maternal and paternal chromosomes. Yet by definition, sex chromosomes of the heterogametic sex lack a homologous partner. Recent studies in a number of systems have shed light on the unique meiotic behavior of heteromorphic sex chromosomes, and highlight both the commonalities and differences in divergent species. During meiotic prophase, the homology-dependent processes of pairing, synapsis, and recombination have been modified in many different ways to ensure segregation of heteromorphic sex chromosomes at the first meiotic division. Additionally, an almost universal feature of heteromorphic sex chromosomes during meiosis is transcriptional silencing, or meiotic sex chromosome inactivation, an essential process proposed to prevent expression of genes deleterious to meiosis in the heterogametic sex as well as to shield unpaired sex chromosomes from recognition by meiotic checkpoints. Comparative analyses of the meiotic behavior of sex chromosomes in nematodes, mammals, and birds reveal important conserved features as well as provide insight into sex chromosome evolution.

  2. No excess gene movement is detected off the avian or lepidopteran Z chromosome.

    Science.gov (United States)

    Toups, Melissa A; Pease, James B; Hahn, Matthew W

    2011-01-01

    Most of our knowledge of sex-chromosome evolution comes from male heterogametic (XX/XY) taxa. With the genome sequencing of multiple female heterogametic (ZZ/ZW) taxa, we can now ask whether there are patterns of evolution common to both sex chromosome systems. In all XX/XY systems examined to date, there is an excess of testis-biased retrogenes moving from the X chromosome to the autosomes, which is hypothesized to result from either sexually antagonistic selection or escape from meiotic sex chromosome inactivation (MSCI). We examined RNA-mediated (retrotransposed) and DNA-mediated gene movement in two independently evolved ZZ/ZW systems, birds (chicken and zebra finch) and lepidopterans (silkworm). Even with sexually antagonistic selection likely operating in both taxa and MSCI having been identified in the chicken, we find no evidence for an excess of genes moving from the Z chromosome to the autosomes in either lineage. We detected no excess for either RNA- or DNA-mediated duplicates, across a range of approaches and methods. We offer some potential explanations for this difference between XX/XY and ZZ/ZW sex chromosome systems, but further work is needed to distinguish among these hypotheses. Regardless of the root causes, we have identified an additional, potentially inherent, difference between XX/XY and ZZ/ZW systems.

  3. Conditional inactivation of the DNA damage response gene Hus1 in mouse testis reveals separable roles for components of the RAD9-RAD1-HUS1 complex in meiotic chromosome maintenance.

    Directory of Open Access Journals (Sweden)

    Amy M Lyndaker

    Full Text Available The RAD9-RAD1-HUS1 (9-1-1 complex is a heterotrimeric PCNA-like clamp that responds to DNA damage in somatic cells by promoting DNA repair as well as ATR-dependent DNA damage checkpoint signaling. In yeast, worms, and flies, the 9-1-1 complex is also required for meiotic checkpoint function and efficient completion of meiotic recombination; however, since Rad9, Rad1, and Hus1 are essential genes in mammals, little is known about their functions in mammalian germ cells. In this study, we assessed the meiotic functions of 9-1-1 by analyzing mice with germ cell-specific deletion of Hus1 as well as by examining the localization of RAD9 and RAD1 on meiotic chromosomes during prophase I. Hus1 loss in testicular germ cells resulted in meiotic defects, germ cell depletion, and severely compromised fertility. Hus1-deficient primary spermatocytes exhibited persistent autosomal γH2AX and RAD51 staining indicative of unrepaired meiotic DSBs, synapsis defects, an extended XY body domain often encompassing partial or whole autosomes, and an increase in structural chromosome abnormalities such as end-to-end X chromosome-autosome fusions and ruptures in the synaptonemal complex. Most of these aberrations persisted in diplotene-stage spermatocytes. Consistent with a role for the 9-1-1 complex in meiotic DSB repair, RAD9 localized to punctate, RAD51-containing foci on meiotic chromosomes in a Hus1-dependent manner. Interestingly, RAD1 had a broader distribution that only partially overlapped with RAD9, and localization of both RAD1 and the ATR activator TOPBP1 to the XY body and to unsynapsed autosomes was intact in Hus1 conditional knockouts. We conclude that mammalian HUS1 acts as a component of the canonical 9-1-1 complex during meiotic prophase I to promote DSB repair and further propose that RAD1 and TOPBP1 respond to unsynapsed chromatin through an alternative mechanism that does not require RAD9 or HUS1.

  4. Conditional inactivation of the DNA damage response gene Hus1 in mouse testis reveals separable roles for components of the RAD9-RAD1-HUS1 complex in meiotic chromosome maintenance.

    Science.gov (United States)

    Lyndaker, Amy M; Lim, Pei Xin; Mleczko, Joanna M; Diggins, Catherine E; Holloway, J Kim; Holmes, Rebecca J; Kan, Rui; Schlafer, Donald H; Freire, Raimundo; Cohen, Paula E; Weiss, Robert S

    2013-01-01

    The RAD9-RAD1-HUS1 (9-1-1) complex is a heterotrimeric PCNA-like clamp that responds to DNA damage in somatic cells by promoting DNA repair as well as ATR-dependent DNA damage checkpoint signaling. In yeast, worms, and flies, the 9-1-1 complex is also required for meiotic checkpoint function and efficient completion of meiotic recombination; however, since Rad9, Rad1, and Hus1 are essential genes in mammals, little is known about their functions in mammalian germ cells. In this study, we assessed the meiotic functions of 9-1-1 by analyzing mice with germ cell-specific deletion of Hus1 as well as by examining the localization of RAD9 and RAD1 on meiotic chromosomes during prophase I. Hus1 loss in testicular germ cells resulted in meiotic defects, germ cell depletion, and severely compromised fertility. Hus1-deficient primary spermatocytes exhibited persistent autosomal γH2AX and RAD51 staining indicative of unrepaired meiotic DSBs, synapsis defects, an extended XY body domain often encompassing partial or whole autosomes, and an increase in structural chromosome abnormalities such as end-to-end X chromosome-autosome fusions and ruptures in the synaptonemal complex. Most of these aberrations persisted in diplotene-stage spermatocytes. Consistent with a role for the 9-1-1 complex in meiotic DSB repair, RAD9 localized to punctate, RAD51-containing foci on meiotic chromosomes in a Hus1-dependent manner. Interestingly, RAD1 had a broader distribution that only partially overlapped with RAD9, and localization of both RAD1 and the ATR activator TOPBP1 to the XY body and to unsynapsed autosomes was intact in Hus1 conditional knockouts. We conclude that mammalian HUS1 acts as a component of the canonical 9-1-1 complex during meiotic prophase I to promote DSB repair and further propose that RAD1 and TOPBP1 respond to unsynapsed chromatin through an alternative mechanism that does not require RAD9 or HUS1.

  5. Activators and repressors: A balancing act for X-inactivation.

    Science.gov (United States)

    Goodrich, Leeanne; Panning, Barbara; Leung, Karen Nicole

    2016-08-01

    In early female embryos X-chromosome inactivation occurs concomitant with up regulation of the non-coding RNA, Xist, on the future inactive X-chromosome. Up regulation of Xist and coating of the future inactive X is sufficient to induce silencing. Therefore unlocking the mechanisms of X-chromosome inactivation requires thorough understanding of the transcriptional regulators, both activators and repressors, which control Xist. Mouse pluripotent embryonic stem cells, which have two active X chromosomes, provide a tractable ex vivo model system for studying X-chromosome inactivation, since this process is triggered by differentiation signals in these cultured cells. Yet there are significant discrepancies found between ex vivo analyses in mouse embryonic stem cells and in vivo studies of early embryos. In this review we elaborate on potential models of how Xist is up regulated on a single X chromosome in female cells and how ex vivo and in vivo analyses enlighten our understanding of the activators and repressors that control this non-coding RNA gene.

  6. Extreme patterns of variance in small populations: placing limits on human Y-chromosome diversity through time in the Vanuatu Archipelago.

    Science.gov (United States)

    Cox, M

    2007-05-01

    Small populations are dominated by unique patterns of variance, largely characterized by rapid drift of allele frequencies. Although the variance components of genetic datasets have long been recognized, most population genetic studies still treat all sampling locations equally despite differences in sampling and effective population sizes. Because excluding the effects of variance can lead to significant biases in historical reconstruction, variance components should be incorporated explicitly into population genetic analyses. The possible magnitude of variance effects in small populations is illustrated here via a case study of Y-chromosome haplogroup diversity in the Vanuatu Archipelago. Deme-based modelling is used to simulate allele frequencies through time, and conservative confidence bounds are placed on the accumulation of stochastic variance effects, including diachronic genetic drift and contemporary sampling error. When the information content of the dataset has been ascertained, demographic models with parameters falling outside the confidence bounds of the variance components can then be accepted with some statistical confidence. Here I emphasize how aspects of the demographic history of a population can be disentangled from stochastic variance effects, and I illustrate the extreme roles of genetic drift and sampling error for many small human population datasets.

  7. Lack of sex chromosome specific meiotic silencing in platypus reveals origin of MSCI in therian mammals

    OpenAIRE

    Daish, Tasman J.; Casey, Aaron E.; Grutzner, Frank

    2015-01-01

    Background In therian mammals heteromorphic sex chromosomes are subject to meiotic sex chromosome inactivation (MSCI) during meiotic prophase I while the autosomes maintain transcriptional activity. The evolution of this sex chromosome silencing is thought to result in retroposition of genes required in spermatogenesis from the sex chromosomes to autosomes. In birds sex chromosome specific silencing appears to be absent and global transcriptional reductions occur through pachytene and sex chr...

  8. Modeling Chromosomes

    Science.gov (United States)

    Robertson, Carol

    2016-01-01

    Learning about chromosomes is standard fare in biology classrooms today. However, students may find it difficult to understand the relationships among the "genome", "chromosomes", "genes", a "gene locus", and "alleles". In the simple activity described in this article, which follows the 5E approach…

  9. Strong Constraint on Human Genes Escaping X-Inactivation Is Modulated by their Expression Level and Breadth in Both Sexes.

    Science.gov (United States)

    Slavney, Andrea; Arbiza, Leonardo; Clark, Andrew G; Keinan, Alon

    2016-02-01

    In eutherian mammals, X-linked gene expression is normalized between XX females and XY males through the process of X chromosome inactivation (XCI). XCI results in silencing of transcription from one ChrX homolog per female cell. However, approximately 25% of human ChrX genes escape XCI to some extent and exhibit biallelic expression in females. The evolutionary basis of this phenomenon is not entirely clear, but high sequence conservation of XCI escapers suggests that purifying selection may directly or indirectly drive XCI escape at these loci. One hypothesis is that this signal results from contributions to developmental and physiological sex differences, but presently there is limited evidence supporting this model in humans. Another potential driver of this signal is selection for high and/or broad gene expression in both sexes, which are strong predictors of reduced nucleotide substitution rates in mammalian genes. Here, we compared purifying selection and gene expression patterns of human XCI escapers with those of X-inactivated genes in both sexes. When we accounted for the functional status of each ChrX gene's Y-linked homolog (or "gametolog"), we observed that XCI escapers exhibit greater degrees of purifying selection in the human lineage than X-inactivated genes, as well as higher and broader gene expression than X-inactivated genes across tissues in both sexes. These results highlight a significant role for gene expression in both sexes in driving purifying selection on XCI escapers, and emphasize these genes' potential importance in human disease.

  10. Cryptic mosaicism involving a second chromosome X in patients with Turner syndrome

    Directory of Open Access Journals (Sweden)

    A. Araújo

    2008-05-01

    Full Text Available The high abortion rate of 45,X embryos indicates that patients with Turner syndrome and 45,X karyotype could be mosaics, in at least one phase of embryo development or cellular lineage, due to the need for the other sex chromosome presence for conceptus to be compatible with life. In cases of structural chromosomal aberrations or hidden mosaicism, conventional cytogenetic techniques can be ineffective and molecular investigation is indicated. Two hundred and fifty patients with Turner syndrome stigmata were studied and 36 who had female genitalia and had been cytogenetically diagnosed as having "pure" 45,X karyotype were selected after 100 metaphases were analyzed in order to exclude mosaicism and the presence of genomic Y-specific sequences (SRY, TSPY, and DAZ was excluded by PCR. Genomic DNA was extracted from peripheral blood and screened by the human androgen receptor (HUMARA assay. The HUMARA gene has a polymorphic CAG repeat and, in the presence of a second chromosome with a different HUMARA allele, a second band will be amplified by PCR. Additionally, the CAG repeats contain two methylation-sensitive HpaII enzyme restriction sites, which can be used to verify skewed inactivation. Twenty-five percent (9/36 of the cases showed a cryptic mosaicism involving a second X and approximately 14% (5/36, or 55% (5/9 of the patients with cryptic mosaicism, also presented skewed inactivation. The laboratory identification of the second X chromosome and its inactivation pattern are important for the clinical management (hormone replacement therapy, and inclusion in an oocyte donation program and prognostic counseling of patients with Turner syndrome.

  11. Key features of the X inactivation process are conserved between marsupials and eutherians.

    Science.gov (United States)

    Mahadevaiah, Shantha K; Royo, Helene; VandeBerg, John L; McCarrey, John R; Mackay, Sarah; Turner, James M A

    2009-09-15

    In female marsupials, X chromosome inactivation (XCI) is imprinted, affecting the paternal X chromosome. One model, supported by recent studies, proposes that XCI in marsupials is achieved through inheritance of an already silent X chromosome from the father, with XCI initiated by meiotic sex chromosome inactivation (MSCI). This model is appealing because marsupials have no Xist gene and the marsupial inactive X chromosome is epigenetically dissimilar to that of mice, apparently lacking repressive histone marks such as H3K27 trimethylation. A central prediction of the meiotic inactivation model of XCI is that silencing of genes on the X chromosome, initiated during male meiosis, is stably maintained during subsequent spermiogenesis. Here we characterize XCI in the male germline and female soma of the marsupial Monodelphis domestica. Contrary to the meiotic inactivation model, we find that X genes silenced by MSCI are reactivated after meiosis and are subsequently inactivated in the female. A reexamination of the female somatic inactive marsupial X chromosome reveals that it does share common properties with that of eutherians, including H3K27 trimethylation and targeting to the perinucleolar compartment. We conclude that aspects of the XCI process are more highly conserved in therian mammals than previously thought.

  12. The importance of having two X chromosomes.

    Science.gov (United States)

    Arnold, Arthur P; Reue, Karen; Eghbali, Mansoureh; Vilain, Eric; Chen, Xuqi; Ghahramani, Negar; Itoh, Yuichiro; Li, Jingyuan; Link, Jenny C; Ngun, Tuck; Williams-Burris, Shayna M

    2016-02-19

    Historically, it was thought that the number of X chromosomes plays little role in causing sex differences in traits. Recently, selected mouse models have been used increasingly to compare mice with the same type of gonad but with one versus two copies of the X chromosome. Study of these models demonstrates that mice with one X chromosome can be strikingly different from those with two X chromosomes, when the differences are not attributable to confounding group differences in gonadal hormones. The number of X chromosomes affects adiposity and metabolic disease, cardiovascular ischaemia/reperfusion injury and behaviour. The effects of X chromosome number are likely the result of inherent differences in expression of X genes that escape inactivation, and are therefore expressed from both X chromosomes in XX mice, resulting in a higher level of expression when two X chromosomes are present. The effects of X chromosome number contribute to sex differences in disease phenotypes, and may explain some features of X chromosome aneuploidies such as in Turner and Klinefelter syndromes.

  13. Genetic architecture of skewed X inactivation in the laboratory mouse.

    Directory of Open Access Journals (Sweden)

    John D Calaway

    Full Text Available X chromosome inactivation (XCI is the mammalian mechanism of dosage compensation that balances X-linked gene expression between the sexes. Early during female development, each cell of the embryo proper independently inactivates one of its two parental X-chromosomes. In mice, the choice of which X chromosome is inactivated is affected by the genotype of a cis-acting locus, the X-chromosome controlling element (Xce. Xce has been localized to a 1.9 Mb interval within the X-inactivation center (Xic, yet its molecular identity and mechanism of action remain unknown. We combined genotype and sequence data for mouse stocks with detailed phenotyping of ten inbred strains and with the development of a statistical model that incorporates phenotyping data from multiple sources to disentangle sources of XCI phenotypic variance in natural female populations on X inactivation. We have reduced the Xce candidate 10-fold to a 176 kb region located approximately 500 kb proximal to Xist. We propose that structural variation in this interval explains the presence of multiple functional Xce alleles in the genus Mus. We have identified a new allele, Xce(e present in Mus musculus and a possible sixth functional allele in Mus spicilegus. We have also confirmed a parent-of-origin effect on X inactivation choice and provide evidence that maternal inheritance magnifies the skewing associated with strong Xce alleles. Based on the phylogenetic analysis of 155 laboratory strains and wild mice we conclude that Xce(a is either a derived allele that arose concurrently with the domestication of fancy mice but prior the derivation of most classical inbred strains or a rare allele in the wild. Furthermore, we have found that despite the presence of multiple haplotypes in the wild Mus musculus domesticus has only one functional Xce allele, Xce(b. Lastly, we conclude that each mouse taxa examined has a different functional Xce allele.

  14. Engineered human dicentric chromosomes show centromere plasticity.

    Science.gov (United States)

    Higgins, Anne W; Gustashaw, Karen M; Willard, Huntington F

    2005-01-01

    The centromere is essential for the faithful distribution of a cell's genetic material to subsequent generations. Despite intense scrutiny, the precise genetic and epigenetic basis for centromere function is still unknown. Here, we have used engineered dicentric human chromosomes to investigate mammalian centromere structure and function. We describe three classes of dicentric chromosomes isolated in different cell lines: functionally monocentric chromosomes, in which one of the two genetically identical centromeres is consistently inactivated; functionally dicentric chromosomes, in which both centromeres are consistently active; and dicentric chromosomes heterogeneous with respect to centromere activity. A study of serial single cell clones from heterogeneous cell lines revealed that while centromere activity is usually clonal, the centromere state (i.e. functionally monocentric or dicentric) in some lines can switch within a growing population of cells. Because pulsed field gel analysis indicated that the DNA at the centromeres of these chromosomes did not change detectably, this switching of the centromere state is most likely due to epigenetic changes. Inactivation of one of the two active centromeres in a functionally dicentric chromosome was observed in a percentage of cells after treatment with Trichostatin A, an inhibitor of histone deacetylation. This study provides evidence that the activity of human centromeres, while largely stable, can be subject to dynamic change, most likely due to epigenetic modification.

  15. Deletion of DXZ4 on the human inactive X chromosome alters higher-order genome architecture.

    Science.gov (United States)

    Darrow, Emily M; Huntley, Miriam H; Dudchenko, Olga; Stamenova, Elena K; Durand, Neva C; Sun, Zhuo; Huang, Su-Chen; Sanborn, Adrian L; Machol, Ido; Shamim, Muhammad; Seberg, Andrew P; Lander, Eric S; Chadwick, Brian P; Aiden, Erez Lieberman

    2016-08-02

    During interphase, the inactive X chromosome (Xi) is largely transcriptionally silent and adopts an unusual 3D configuration known as the "Barr body." Despite the importance of X chromosome inactivation, little is known about this 3D conformation. We recently showed that in humans the Xi chromosome exhibits three structural features, two of which are not shared by other chromosomes. First, like the chromosomes of many species, Xi forms compartments. Second, Xi is partitioned into two huge intervals, called "superdomains," such that pairs of loci in the same superdomain tend to colocalize. The boundary between the superdomains lies near DXZ4, a macrosatellite repeat whose Xi allele extensively binds the protein CCCTC-binding factor. Third, Xi exhibits extremely large loops, up to 77 megabases long, called "superloops." DXZ4 lies at the anchor of several superloops. Here, we combine 3D mapping, microscopy, and genome editing to study the structure of Xi, focusing on the role of DXZ4 We show that superloops and superdomains are conserved across eutherian mammals. By analyzing ligation events involving three or more loci, we demonstrate that DXZ4 and other superloop anchors tend to colocate simultaneously. Finally, we show that deleting DXZ4 on Xi leads to the disappearance of superdomains and superloops, changes in compartmentalization patterns, and changes in the distribution of chromatin marks. Thus, DXZ4 is essential for proper Xi packaging.

  16. Role of ATRX in chromatin structure and function: implications for chromosome instability and human disease.

    Science.gov (United States)

    De La Fuente, Rabindranath; Baumann, Claudia; Viveiros, Maria M

    2011-08-01

    Functional differentiation of chromatin structure is essential for the control of gene expression, nuclear architecture, and chromosome stability. Compelling evidence indicates that alterations in chromatin remodeling proteins play an important role in the pathogenesis of human disease. Among these, α-thalassemia mental retardation X-linked protein (ATRX) has recently emerged as a critical factor involved in heterochromatin formation at mammalian centromeres and telomeres as well as facultative heterochromatin on the murine inactive X chromosome. Mutations in human ATRX result in an X-linked neurodevelopmental condition with various degrees of gonadal dysgenesis (ATRX syndrome). Patients with ATRX syndrome may exhibit skewed X chromosome inactivation (XCI) patterns, and ATRX-deficient mice exhibit abnormal imprinted XCI in the trophoblast cell line. Non-random or skewed XCI can potentially affect both the onset and severity of X-linked disease. Notably, failure to establish epigenetic modifications associated with the inactive X chromosome (Xi) results in several conditions that exhibit genomic and chromosome instability such as fragile X syndrome as well as cancer development. Insight into the molecular mechanisms of ATRX function and its interacting partners in different tissues will no doubt contribute to our understanding of the pathogenesis of ATRX syndrome as well as the epigenetic origins of aneuploidy. In turn, this knowledge will be essential for the identification of novel drug targets and diagnostic tools for cancer progression as well as the therapeutic management of global epigenetic changes commonly associated with malignant neoplastic transformation.

  17. Break-seq reveals hydroxyurea-induced chromosome fragility as a result of unscheduled conflict between DNA replication and transcription.

    Science.gov (United States)

    Hoffman, Elizabeth A; McCulley, Andrew; Haarer, Brian; Arnak, Remigiusz; Feng, Wenyi

    2015-03-01

    We have previously demonstrated that in Saccharomyces cerevisiae replication, checkpoint inactivation via a mec1 mutation leads to chromosome breakage at replication forks initiated from virtually all origins after transient exposure to hydroxyurea (HU), an inhibitor of ribonucleotide reductase. Here we sought to determine whether all replication forks containing single-stranded DNA gaps have equal probability of producing double-strand breaks (DSBs) when cells attempt to recover from HU exposure. We devised a new methodology, Break-seq, that combines our previously described DSB labeling with next generation sequencing to map chromosome breaks with improved sensitivity and resolution. We show that DSBs preferentially occur at genes transcriptionally induced by HU. Notably, different subsets of the HU-induced genes produced DSBs in MEC1 and mec1 cells as replication forks traversed a greater distance in MEC1 cells than in mec1 cells during recovery from HU. Specifically, while MEC1 cells exhibited chromosome breakage at stress-response transcription factors, mec1 cells predominantly suffered chromosome breakage at transporter genes, many of which are the substrates of those transcription factors. We propose that HU-induced chromosome fragility arises at higher frequency near HU-induced genes as a result of destabilized replication forks encountering transcription factor binding and/or the act of transcription. We further propose that replication inhibitors can induce unscheduled encounters between replication and transcription and give rise to distinct patterns of chromosome fragile sites.

  18. Chromosome painting of Z and W sex chromosomes in Characidium (Characiformes, Crenuchidae).

    Science.gov (United States)

    Pazian, Marlon F; Shimabukuro-Dias, Cristiane Kioko; Pansonato-Alves, José Carlos; Oliveira, Claudio; Foresti, Fausto

    2013-03-01

    Some species of the genus Characidium have heteromorphic ZZ/ZW sex chromosomes with a totally heterochromatic W chromosome. Methods for chromosome microdissection associated with chromosome painting have become important tools for cytogenetic studies in Neotropical fish. In Characidium cf. fasciatum, the Z chromosome contains a pericentromeric heterochromatin block, whereas the W chromosome is completely heterochromatic. Therefore, a probe was produced from the W chromosome through microdissection and degenerate oligonucleotide-primed polymerase chain reaction amplification. FISH was performed using the W probe on the chromosomes of specimens of this species. This revealed expressive marks in the pericentromeric region of the Z chromosome as well as a completely painted W chromosome. When applying the same probe on chromosome preparations of C. cf. gomesi and Characidium sp., a pattern similar to C. cf. fasciatum was found, while C. cf. zebra, C. cf. lagosantense and Crenuchus spilurus species showed no hybridization signals. Structural changes in the chromosomes of an ancestral sexual system in the group that includes the species C. cf. gomesi, C. cf. fasciatum and Characidium sp., could have contributed to the process of speciation and could represent a causal mechanism of chromosomal diversification in this group. The heterochromatinization process possibly began in homomorphic and homologous chromosomes of an ancestral form, and this process could have given rise to the current patterns found in the species with sex chromosome heteromorphism.

  19. MDC1 directs chromosome-wide silencing of the sex chromosomes in male germ cells.

    Science.gov (United States)

    Ichijima, Yosuke; Ichijima, Misako; Lou, Zhenkun; Nussenzweig, André; Camerini-Otero, R Daniel; Chen, Junjie; Andreassen, Paul R; Namekawa, Satoshi H

    2011-05-01

    Chromosome-wide inactivation is an epigenetic signature of sex chromosomes. The mechanism by which the chromosome-wide domain is recognized and gene silencing is induced remains unclear. Here we identify an essential mechanism underlying the recognition of the chromosome-wide domain in the male germline. We show that mediator of DNA damage checkpoint 1 (MDC1), a binding partner of phosphorylated histone H2AX (γH2AX), defines the chromosome-wide domain, initiates meiotic sex chromosome inactivation (MSCI), and leads to XY body formation. Importantly, MSCI consists of two genetically separable steps. The first step is the MDC1-independent recognition of the unsynapsed axis by DNA damage response (DDR) factors such as ataxia telangiectasia and Rad3-related (ATR), TOPBP1, and γH2AX. The second step is the MDC1-dependent chromosome-wide spreading of DDR factors to the entire chromatin. Furthermore, we demonstrate that, in somatic cells, MDC1-dependent amplification of the γH2AX signal occurs following replicative stress and is associated with transcriptional silencing. We propose that a common DDR pathway underlies both MSCI and the response of somatic cells to replicative stress. These results establish that the DDR pathway centered on MDC1 triggers epigenetic silencing of sex chromosomes in germ cells.

  20. Mammalian chromosomes contain cis-acting elements that control replication timing, mitotic condensation, and stability of entire chromosomes.

    Science.gov (United States)

    Thayer, Mathew J

    2012-09-01

    Recent studies indicate that mammalian chromosomes contain discrete cis-acting loci that control replication timing, mitotic condensation, and stability of entire chromosomes. Disruption of the large non-coding RNA gene ASAR6 results in late replication, an under-condensed appearance during mitosis, and structural instability of human chromosome 6. Similarly, disruption of the mouse Xist gene in adult somatic cells results in a late replication and instability phenotype on the X chromosome. ASAR6 shares many characteristics with Xist, including random mono-allelic expression and asynchronous replication timing. Additional "chromosome engineering" studies indicate that certain chromosome rearrangements affecting many different chromosomes display this abnormal replication and instability phenotype. These observations suggest that all mammalian chromosomes contain "inactivation/stability centers" that control proper replication, condensation, and stability of individual chromosomes. Therefore, mammalian chromosomes contain four types of cis-acting elements, origins, telomeres, centromeres, and "inactivation/stability centers", all functioning to ensure proper replication, condensation, segregation, and stability of individual chromosomes.

  1. Correlation of chromosome patterns in human leukemic cells with exposure to chemicals and/or radiation. Progress report, January 1, 1980-Dec 31, 1980. [Consequences of radiotherapy and/or chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, J. D.

    1980-09-01

    The relationship of the chromosome pattern in leukemic cells to prior disease and to the type of therapy are summarized. Although the karyotype seen in secondary ANLL is distinctly different from that seen in the primary malignancy, the nature of the primary disease may influence the pattern of karyotypic changes seen in the leukemic cell. This notion is very speculative and is based on limited observations. Two of three patients with leukemia following multiple myeloma were unique in that they were the only ones whose leukemic cells had more than 48 chromosomes, with +1, +6, +8, +21; this constellation of abnormalities was not seen in any of the other patients. Since most of the patients had received both radiotherapy and chemotherapy, it is difficult to determine whether specific chromosome changes are related more closely to one rather than the other of these types of therapy. It appears, however, that combined therapy is much more likely to result in abnormalities of both No. 5 and No. 7 (9/15 patients) than is either modality used alone (1/12). (ERB)

  2. Dicentric Chromosome Formation and Epigenetics of Centromere Formation in Plants

    Institute of Scientific and Technical Information of China (English)

    Shulan Fu; Zhi Gao; James Birchler; Fangpu Han

    2012-01-01

    Plant centromeres are generally composed of tandem arrays of simple repeats that form a complex chromosome locus where the kinetochore forms and microtubules attach during mitosis and meiosis.Each chromosome has one centromere region,which is essential for accurate division of the genetic material.Recently,chromosomes containing two centromere regions (called dicentric chromosomes)have been found in maize and wheat.Interestingly,some dicentric chromosomes are stable because only one centromere is active and the other one is inactivated.Because such arrays maintain their typical structure for both active and inactive centromeres,the specification of centromere activity has an epigenetic component independent of the DNA sequence.Under some circumstances,the inactive centromeres may recover centromere function,which is called centromere reactivation.Recent studies have highlighted the important changes,such as DNA methylation and histone modification,that occur during centromere inactivation and reactivation.

  3. Dicentric chromosome formation and epigenetics of centromere formation in plants.

    Science.gov (United States)

    Fu, Shulan; Gao, Zhi; Birchler, James; Han, Fangpu

    2012-03-20

    Plant centromeres are generally composed of tandem arrays of simple repeats that form a complex chromosome locus where the kinetochore forms and microtubules attach during mitosis and meiosis. Each chromosome has one centromere region, which is essential for accurate division of the genetic material. Recently, chromosomes containing two centromere regions (called dicentric chromosomes) have been found in maize and wheat. Interestingly, some dicentric chromosomes are stable because only one centromere is active and the other one is inactivated. Because such arrays maintain their typical structure for both active and inactive centromeres, the specification of centromere activity has an epigenetic component independent of the DNA sequence. Under some circumstances, the inactive centromeres may recover centromere function, which is called centromere reactivation. Recent studies have highlighted the important changes, such as DNA methylation and histone modification, that occur during centromere inactivation and reactivation.

  4. Higher order structure of chromosomes.

    Science.gov (United States)

    Okada, T A; Comings, D E

    1979-04-01

    Isolated Chinese hamster metaphase chromosomes were resuspended in 4 M ammonium acetate and spread on a surface of distilled water or 0.15 to 0.5 M ammonium acetate. The DNA was released in the form of a regular series of rosettes connected by interrossette DNA. The mean length of the rosette DNA was 14 micron, similar to the mean length of 10 micron for chromomere DNA of Drosophila polytene chromosomes. The mean interrosette DNA was 4.2 micron. SDS gel electrophoresis of the chromosomal nonhistone proteins showed them to be very similar to nuclear nonhistone proteins except for the presence of more actin and tubulin. Nuclear matrix proteins were present in the chromosomes and may play a role in forming the rosettes. Evidence that the rosette pattern is artifactual versus the possibility that it represents a real organizational substructure of the chromosomes is reviewed.

  5. Synthetic chromosomes.

    Science.gov (United States)

    Schindler, Daniel; Waldminghaus, Torsten

    2015-11-01

    What a living organism looks like and how it works and what are its components-all this is encoded on DNA, the genetic blueprint. Consequently, the way to change an organism is to change its genetic information. Since the first pieces of recombinant DNA have been used to transform cells in the 1970s, this approach has been enormously extended. Bigger and bigger parts of the genetic information have been exchanged or added over the years. Now we are at a point where the construction of entire chromosomes becomes a reachable goal and first examples appear. This development leads to fundamental new questions, for example, about what is possible and desirable to build or what construction rules one needs to follow when building synthetic chromosomes. Here we review the recent progress in the field, discuss current challenges and speculate on the appearance of future synthetic chromosomes.

  6. The role of epigenetic inactivation of 14-3-3σin human cancer

    Institute of Scientific and Technical Information of China (English)

    Dmitri LODYGIN; Heiko HERMEKING

    2005-01-01

    Cancer cells show characteristic alterations in DNA methylation patterns. Aberrant CpG methylation of specific promoters results in inactivation of tumor suppressor genes and therefore plays an important role in carcinogenesis. The p53-regulated gene 14-3-3σ undergoes frequent epigenetic silencing in several types of cancer, including carcinoma of the breast, prostate, and skin, suggesting that the loss of 14-3-3σ expression may be causally involved in tumor progression.Functional studies demonstrated that 14-3-3σ is involved in cell-cycle control and prevents the accumulation of chromosomal damage. The recent identification of novel 14-3-3σ-associated proteins by a targeted proteomics approach implies that 14-3-3σ regulates diverse cellular processes, which may become deregulated after silencing of 14-3-3σ expression in cancer cells.

  7. Correlation of chromosome patterns in human leukemic cells with exposure to chemicals and/or radiation. Comprehensive progress report, January 1, 1980-December 31, 1982

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, J.D.

    1982-06-01

    The observations that two particular translocations are consistently associated with specific differentiation stages of acute nonlymphocytic leukemia were confirmed. These are the translocation between chromosomes 8 and 21 in acute myeloblastic leukemia with maturation and the translocation between chromosomes 15 and 17 in acute promyelocytic leukemia. The observation of others that structural rearrangements involving the long arm of No. 11 are frequently seen in acute monoblastic leukemia was also confirmed. The chromosome aberrations that are observed in the great majority of patients with acute leukemia secondary to cytotoxic therapy were defined. Thus of 47 patients with secondary acute nonlymphocytic leukemia, an aneuploid clone was seen in 44, and 39 of the 44 had a loss of part or all of No. 5 and/or No. 7. I have been able to localize the region of chromosome No. 7, loss of which is important for the development of leukemia was localized. Patients with ANLL de novo whose occupational histories suggest exposure to potentially mutagenic agents have a higher frequency of aberrations involving Nos. 5 and/or 7, than do patients not so exposed. Thus 50% of exposed versus 10% of nonexposed patients had aberrations of Nos. 5 or 7.

  8. Mechanisms and evolutionary patterns of mammalian and avian dosage compensation.

    Directory of Open Access Journals (Sweden)

    Philippe Julien

    Full Text Available As a result of sex chromosome differentiation from ancestral autosomes, male mammalian cells only contain one X chromosome. It has long been hypothesized that X-linked gene expression levels have become doubled in males to restore the original transcriptional output, and that the resulting X overexpression in females then drove the evolution of X inactivation (XCI. However, this model has never been directly tested and patterns and mechanisms of dosage compensation across different mammals and birds generally remain little understood. Here we trace the evolution of dosage compensation using extensive transcriptome data from males and females representing all major mammalian lineages and birds. Our analyses suggest that the X has become globally upregulated in marsupials, whereas we do not detect a global upregulation of this chromosome in placental mammals. However, we find that a subset of autosomal genes interacting with X-linked genes have become downregulated in placentals upon the emergence of sex chromosomes. Thus, different driving forces may underlie the evolution of XCI and the highly efficient equilibration of X expression levels between the sexes observed for both of these lineages. In the egg-laying monotremes and birds, which have partially homologous sex chromosome systems, partial upregulation of the X (Z in birds evolved but is largely restricted to the heterogametic sex, which provides an explanation for the partially sex-biased X (Z expression and lack of global inactivation mechanisms in these lineages. Our findings suggest that dosage reductions imposed by sex chromosome differentiation events in amniotes were resolved in strikingly different ways.

  9. Age-dependent chromosomal distribution of male-biased genes in Drosophila.

    Science.gov (United States)

    Zhang, Yong E; Vibranovski, Maria D; Krinsky, Benjamin H; Long, Manyuan

    2010-11-01

    We investigated the correlation between the chromosomal location and age distribution of new male-biased genes formed by duplications via DNA intermediates (DNA-level) or by de novo origination in Drosophila. Our genome-wide analysis revealed an excess of young X-linked male-biased genes. The proportion of X-linked male-biased genes then diminishes through time, leading to an autosomal excess of male-biased genes. The switch between X-linked and autosomal enrichment of male-biased genes was also present in the distribution of both protein-coding genes on the D. pseudoobscura neo-X chromosome and microRNA genes of D. melanogaster. These observations revealed that the evolution of male-biased genes is more complicated than the previously detected one-step X→A gene traffic and the enrichment of the male-biased genes on autosomes. The pattern we detected suggests that the interaction of various evolutionary forces such as the meiotic sex chromosome inactivation (MSCI), faster-X effect, and sexual antagonism in the male germline might have shaped the chromosomal distribution of male-biased genes on different evolutionary time scales.

  10. Imbalance between the expression dosages of X-chromosome and autosomal genes in mammalian oocytes.

    Science.gov (United States)

    Fukuda, Atsushi; Tanino, Motohiko; Matoba, Ryo; Umezawa, Akihiro; Akutsu, Hidenori

    2015-09-15

    Oocytes have unique characteristics compared with other cell types. In mouse and human oocytes, two X chromosomes are maintained in the active state. Previous microarray studies have shown that the balance of the expression state is maintained in haploid oocytes. Here, we investigated transcripts using RNA-sequence technology in mouse and human oocytes. The median expression ratio between X chromosome and autosomal genes (X:A) in immature mouse oocytes increased as the gene expression levels increased, reaching a value of 1. However, the ratio in mature oocytes was under 1 for all expression categories. Moreover, we observed a markedly low ratio resulting from the bimodal expression patterns of X-linked genes. The low X:A expression ratio in mature oocyte was independent of DNA methylation. While mature human oocytes exhibited a slightly low X:A expression ratio, this was the result of the skewed high frequency of lowly expressed X-linked genes rather than the bimodal state. We propose that this imbalance between the expression dosages of X-chromosome and autosomal genes is a feature of transcripts in mammalian oocytes lacking X-chromosome inactivation.

  11. Chromosomal divergence and evolutionary inferences in Rhodniini based on the chromosomal location of ribosomal genes

    Directory of Open Access Journals (Sweden)

    Sebastian Pita

    2013-05-01

    Full Text Available In this study, we used fluorescence in situ hybridisation to determine the chromosomal location of 45S rDNA clusters in 10 species of the tribe Rhodniini (Hemiptera: Reduviidae: Triatominae. The results showed striking inter and intraspecific variability, with the location of the rDNA clusters restricted to sex chromosomes with two patterns: either on one (X chromosome or both sex chromosomes (X and Y chromosomes. This variation occurs within a genus that has an unchanging diploid chromosome number (2n = 22, including 20 autosomes and 2 sex chromosomes and a similar chromosome size and genomic DNA content, reflecting a genome dynamic not revealed by these chromosome traits. The rDNA variation in closely related species and the intraspecific polymorphism in Rhodnius ecuadoriensis suggested that the chromosomal position of rDNA clusters might be a useful marker to identify recently diverged species or populations. We discuss the ancestral position of ribosomal genes in the tribe Rhodniini and the possible mechanisms involved in the variation of the rDNA clusters, including the loss of rDNA loci on the Y chromosome, transposition and ectopic pairing. The last two processes involve chromosomal exchanges between both sex chromosomes, in contrast to the widely accepted idea that the achiasmatic sex chromosomes of Heteroptera do not interchange sequences.

  12. Chromosome Analysis

    Science.gov (United States)

    1998-01-01

    Perceptive Scientific Instruments, Inc., provides the foundation for the Powergene line of chromosome analysis and molecular genetic instrumentation. This product employs image processing technology from NASA's Jet Propulsion Laboratory and image enhancement techniques from Johnson Space Center. Originally developed to send pictures back to earth from space probes, digital imaging techniques have been developed and refined for use in a variety of medical applications, including diagnosis of disease.

  13. Assignment of human sprouty 4 gene to chromosome segment 5q32∼33 and analysis of its pattern of expression

    Indian Academy of Sciences (India)

    Hua Liu; Jin-Zhong Chen; Shao-Hua Gu; Jian-Liang Dai; En-Pang Zhao; Lu Huang; Wang-Xiang Xu; Yi Xie; Yu-Min Mao

    2003-04-01

    The human sprouty 4 (SPYR4) gene was localized to chromosome band 5q32∼33 by screening the Stanford radiation hybrid G3 panel using a SPRY4-specific primer pair for PCR. Northern blot analysis revealed two different mRNAs (5 kb and 2 kb) in liver, skeletal muscle, heart, lung, kidney, spleen, placenta and small intestine. Reverse transcriptase-PCR analysis showed that SPYR4 was expressed in all tested tissues to different levels.

  14. X-chromosome kiss and tell: how the Xs go their separate ways.

    Science.gov (United States)

    Anguera, M C; Sun, B K; Xu, N; Lee, J T

    2006-01-01

    Loci associated with noncoding RNAs have important roles in X-chromosome inactivation (XCI), the dosage compensation mechanism by which one of two X chromosomes in female cells becomes transcriptionally silenced. The Xs start out as epigenetically equivalent chromosomes, but XCI requires a cell to treat two identical X chromosomes in completely different ways: One X chromosome must remain transcriptionally active while the other becomes repressed. In the embryo of eutherian mammals, the choice to inactivate the maternal or paternal X chromosome is random. The fact that the Xs always adopt opposite fates hints at the existence of a trans-sensing mechanism to ensure the mutually exclusive silencing of one of the two Xs. This paper highlights recent evidence supporting a model for mutually exclusive choice that involves homologous chromosome pairing and the placement of asymmetric chromatin marks on the two Xs.

  15. X inactivation counting and choice is a stochastic process : evidence for involvement of an X-linked activator

    NARCIS (Netherlands)

    Monkhorst, Kim; Jonkers, Iris; Rentmeester, Eveline; Grosveld, Frank; Gribnau, Joost

    2008-01-01

    Female mammalian cells achieve dosage compensation of X-encoded genes by X chromosome inactivation (XCI). This process is thought to involve X chromosome counting and choice. To explore how this process is initiated, we analyzed XCI in tetraploid XXXX, XXXY, and XXYY embryonic stem cells and found t

  16. APC and chromosome instability in colorectal cancer

    Directory of Open Access Journals (Sweden)

    C. M. Cabrera

    Full Text Available Colon cancer is a common disease that can be sporadic or familial. An inactivated adenomatous polyposis coli (APC suppressor gene is found in over 80% of colorectal tumors, this being an early alteration in the development of adenomatous polyps. APC function is not only critical for tumor initiation and progression, and chromosome instability (CIN is another characteristic dependent at least partly on APC mutations.

  17. Expression patterns of WT-1 and Bcr-Abl measured by TaqMan quantitative real-time RT-PCR during follow-up of leukemia patients with the Ph chromosome

    Institute of Scientific and Technical Information of China (English)

    CHEN Zi-xing陈子兴; Jaspal Kaeda; Sue Saunders; John M Goldman

    2004-01-01

    Background This study was designed to quantitatively measure WT-1 expression levels in patients with chronic myelogenous leukemia (CML) and acute lymphoblastic leukemia (ALL) during follow-up and to clarify the value of WT-1 as a molecular marker in minimal residual disease monitoring.Methods The TaqMan quantitative real-time RT-PCR method was established by using cloned WT-1 cDNA or synthesized oligonucleotides resembling WT-1 cDNA fragments in limit dilution as template until a stable and reliable standard curve was obtained. In a 25-month follow-up, the transcriptional levels of WT-1, Bcr-Abl, and Abl gene, were quantitatively measured in bone marrow cells from 25 CML or acute lymphoblastic leukemia (ALL) patients with the Ph chromosome. In addition, the expression of these genes in 40 samples of normal peripheral blood was also examined using the same method. The ratios of WT-1/Abl and Bcr-Abl/Abl were both plotted, and the two expression patterns were compared as well as their clinical significance.Results The levels of WT-1 expression in normal peripheral blood were detectable. In CML and Ph positive ALL patients, WT-1 expression levels changed in parallel with the Bcr-Abl expression pattern as the disease progressed or responded to effective treatment.Conclusion WT-1 expression provides a novel molecular marker in addition to Bcr-Abl for monitoring minimal residual disease (MRD) and targeting therapy in Ph chromosome-positive leukemia patients.

  18. Hydrazine inactivates bacillus spores

    Science.gov (United States)

    Schubert, Wayne; Plett, G. A.; Yavrouian, A. H.; Barengoltz, J.

    2005-01-01

    Planetary Protection places requirements on the maximum number of viable bacterial spores that may be delivered by a spacecraft to another solar system body. Therefore, for such space missions, the spores that may be found in hydrazine are of concern. A proposed change in processing procedures that eliminated a 0.2 um filtration step propmpted this study to ensure microbial contamination issue existed, especially since no information was found in the literature to substantiate bacterial spore inactivation by hydrazine.

  19. [Dosage compensation mechanism of X chromosome].

    Science.gov (United States)

    Wang, Yan-Yun; Chen, Mei; Li, Bin

    2012-08-01

    Dosage compensation mechanism is crucial for the balance expression of X chromosome genes, which ensures the protein or enzyme encoded by the X chromosome to be equal or almost equal expression amounts between males and females. However, different organisms have evolved distinct dosage compensation strategies, and so far three kinds of dosage compensation strategies among organisms have been reported. The first strategy is that the single male X chromosome expression is doubly activated; the second one is to inactivate one female X chromosome by leaving both sexes with one active allele; and the third one is to reduce the expression to half activity in both X chromosomes of the female. The study of dosage compensation will be useful to reveal the mechanism of regulation of X-linked genes as well as the evolution and the differentiation progress of the sex chromosome, and it can also contribute to illustrate mutation and distortion of sex chromosome. Therefore, this paper briefly reviewed and discussed the progresses and prospects of the important mechanism of dosage compensation.

  20. Centromere activity in dicentric small supernumerary marker chromosomes.

    Science.gov (United States)

    Ewers, Elisabeth; Yoda, Kinya; Hamid, Ahmed B; Weise, Anja; Manvelyan, Marina; Liehr, Thomas

    2010-07-01

    Twenty-five dicentric small supernumerary marker chromosomes (sSMC) derived from #13/21, #14, #15, #18, and #22 were studied by immunohistochemistry for their centromeric activity. Centromere protein (CENP)-B was applied as marker for all centromeres and CENP-C to label the active ones. Three different 'predominant' activation patterns could be observed, i.e., centric fusion or either only one or all two centromeres were active. In one inherited case, the same activation pattern was found in mother and son. In acrocentric-derived sSMC, all three activation patterns could be present. In contrary, in chromosome 18-derived sSMC, only the fusion type was observed. In concordance with previous studies a certain centromeric plasticity was observed in up to 13% of the cells of an individual case. Surprisingly, the obtained data suggests a possible influence of the sSMC carrier's gender on the implementation of the predominant activation pattern; especially, only one active centromere was found more frequently in female than in male carriers. Also, it might be suggested that dicentric sSMC with one active centromere could be less stable than such with two active ones-centromeric plasticity might have an influence here, as well. Also, centromere activity in acrocentric-derived dicentrics could be influenced by heteromorphisms of the corresponding short arms. Finally, evidence is provided that the closer the centromeres of a dicentric are and if they are not fused, the more likely it was that both of them became active. In concordance and refinement with previous studies, a distance of 1.4 Mb up to about 13 Mb the two active centromere state was favored, while centromeric distance of over approximately 15 Mb lead to inactivation of one centromere. Overall, here, the first and largest ever undertaken study in dicentric sSMC is presented, providing evidence that the centromeric activation pattern is, and parental origin may be of interest for their biology. Influence of

  1. The demoiselle of X-inactivation: 50 years old and as trendy and mesmerising as ever.

    Directory of Open Access Journals (Sweden)

    Céline Morey

    2011-07-01

    Full Text Available In humans, sexual dimorphism is associated with the presence of two X chromosomes in the female, whereas males possess only one X and a small and largely degenerate Y chromosome. How do men cope with having only a single X chromosome given that virtually all other chromosomal monosomies are lethal? Ironically, or even typically many might say, women and more generally female mammals contribute most to the job by shutting down one of their two X chromosomes at random. This phenomenon, called X-inactivation, was originally described some 50 years ago by Mary Lyon and has captivated an increasing number of scientists ever since. The fascination arose in part from the realisation that the inactive X corresponded to a dense heterochromatin mass called the "Barr body" whose number varied with the number of Xs within the nucleus and from the many intellectual questions that this raised: How does the cell count the X chromosomes in the nucleus and inactivate all Xs except one? What kind of molecular mechanisms are able to trigger such a profound, chromosome-wide metamorphosis? When is X-inactivation initiated? How is it transmitted to daughter cells and how is it reset during gametogenesis? This review retraces some of the crucial findings, which have led to our current understanding of a biological process that was initially considered as an exception completely distinct from conventional regulatory systems but is now viewed as a paradigm "par excellence" for epigenetic regulation.

  2. The X chromosome and immune associated genes.

    Science.gov (United States)

    Bianchi, Ilaria; Lleo, Ana; Gershwin, M Eric; Invernizzi, Pietro

    2012-05-01

    The X chromosome is known to contain the largest number of immune-related genes of the whole human genome. For this reason, X chromosome has recently become subject of great interest and attention and numerous studies have been aimed at understanding the role of genes on the X chromosome in triggering and maintaining the autoimmune aggression. Autoimmune diseases are indeed a growing heath burden affecting cumulatively up to 10% of the general population. It is intriguing that most X-linked primary immune deficiencies carry significant autoimmune manifestations, thus illustrating the critical role played by products of single gene located on the X chromosome in the onset, function and homeostasis of the immune system. Again, the plethora of autoimmune stigmata observed in patients with Turner syndrome, a disease due to the lack of one X chromosome or the presence of major X chromosome deletions, indicate that X-linked genes play a unique and major role in autoimmunity. There have been several reports on a role of X chromosome gene dosage through inactivation or duplication in women with autoimmune diseases, for example through a higher rate of circulating cells with a single X chromosome (i.e. with X monosomy). Finally, a challenge for researchers in the coming years will be to dissect the role for the large number of X-linked microRNAs from the perspective of autoimmune disease development. Taken together, X chromosome might well constitute the common trait of the susceptibility to autoimmune diseases, other than to explain the female preponderance of these conditions. This review will focus on the available evidence on X chromosome changes and discuss their potential implications and limitations.

  3. Temporal genomic evolution of bird sex chromosomes

    DEFF Research Database (Denmark)

    Wang, Zongji; Zhang, Jilin; Yang, Wei;

    2014-01-01

    BACKGROUND: Sex chromosomes exhibit many unusual patterns in sequence and gene expression relative to autosomes. Birds have evolved a female heterogametic sex system (male ZZ, female ZW), through stepwise suppression of recombination between chrZ and chrW. To address the broad patterns and complex...... driving forces of Z chromosome evolution, we analyze here 45 newly available bird genomes and four species' transcriptomes, over their course of recombination loss between the sex chromosomes. RESULTS: We show Z chromosomes in general have a significantly higher substitution rate in introns and synonymous...... ('fast-Z' evolution). And species with a lower level of intronic heterozygosities tend to evolve even faster on the Z chromosome. Further analysis of fast-evolving genes' enriched functional categories and sex-biased expression patterns support that, fast-Z evolution in birds is mainly driven by genetic...

  4. Scaling Chromosomes for an Evolutionary Karyotype: A Chromosomal Tradeoff between Size and Number across Woody Species.

    Science.gov (United States)

    Liang, Guolu; Chen, Hong

    2015-01-01

    This study aims to examine the expected scaling relationships between chromosome size and number across woody species and to clarify the importance of the scaling for the maintenance of chromosome diversity by analyzing the scaling at the inter- & intra-chromosomal level. To achieve for the goals, chromosome trait data were extracted for 191 woody species (including 56 evergreen species and 135 deciduous species) from the available literature. Cross-species analyses revealed a tradeoff among chromosomes between chromosome size and number, demonstrating there is selective mechanism crossing chromosomes among woody species. And the explanations for the result were presented from intra- to inter-chromosome contexts that the scaling may be compromises among scale symmetry, mechanical requirements, and resource allocation across chromosomes. Therein, a 3/4 scaling pattern was observed between total chromosomes and m-chromosomes within nucleus which may imply total chromosomes may evolve from more to less. In addition, the primary evolutionary trend of karyotype and the role of m-chromosomes in the process of karyotype evolution were also discussed.

  5. Chromosome-specific segmentation revealed by structural analysis of individually isolated chromosomes.

    Science.gov (United States)

    Kitada, Kunio; Taima, Akira; Ogasawara, Kiyomoto; Metsugi, Shouichi; Aikawa, Satoko

    2011-04-01

    Analysis of structural rearrangements at the individual chromosomal level is still technologically challenging. Here we optimized a chromosome isolation method using fluorescent marker-assisted laser-capture and laser-beam microdissection and applied it to structural analysis of two aberrant chromosomes found in a lung cancer cell line. A high-density array-comparative genomic hybridization (array-CGH) analysis of DNA samples prepared from each of the chromosomes revealed that these two chromosomes contained 296 and 263 segments, respectively, ranging from 1.5 kb to 784.3 kb in size, derived from different portions of chromosome 8. Among these segments, 242 were common in both aberrant chromosomes, but 75 were found to be chromosome-specific. Sequences of 263 junction sites connecting the ends of segments were determined using a PCR/Sanger-sequencing procedure. Overlapping microhomologies were found at 169 junction sites. Junction partners came from various portions of chromosome 8 and no biased pattern in the positional distribution of junction partners was detected. These structural characteristics suggested the occurrence of random fragmentation of the entire chromosome 8 followed by random rejoining of these fragments. Based on that, we proposed a model to explain how these aberrant chromosomes are formed. Through these structural analyses, it was demonstrated that the optimized chromosome isolation method described here can provide high-quality chromosomal DNA for high resolution array-CGH analysis and probably for massively parallel sequencing analysis.

  6. Sex-differential selection and the evolution of X inactivation strategies.

    Directory of Open Access Journals (Sweden)

    Tim Connallon

    2013-04-01

    Full Text Available X inactivation--the transcriptional silencing of one X chromosome copy per female somatic cell--is universal among therian mammals, yet the choice of which X to silence exhibits considerable variation among species. X inactivation strategies can range from strict paternally inherited X inactivation (PXI, which renders females haploid for all maternally inherited alleles, to unbiased random X inactivation (RXI, which equalizes expression of maternally and paternally inherited alleles in each female tissue. However, the underlying evolutionary processes that might account for this observed diversity of X inactivation strategies remain unclear. We present a theoretical population genetic analysis of X inactivation evolution and specifically consider how conditions of dominance, linkage, recombination, and sex-differential selection each influence evolutionary trajectories of X inactivation. The results indicate that a single, critical interaction between allelic dominance and sex-differential selection can select for a broad and continuous range of X inactivation strategies, including unequal rates of inactivation between maternally and paternally inherited X chromosomes. RXI is favored over complete PXI as long as alleles deleterious to female fitness are sufficiently recessive, and the criteria for RXI evolution is considerably more restrictive when fitness variation is sexually antagonistic (i.e., alleles deleterious to females are beneficial to males relative to variation that is deleterious to both sexes. Evolutionary transitions from PXI to RXI also generally increase mean relative female fitness at the expense of decreased male fitness. These results provide a theoretical framework for predicting and interpreting the evolution of chromosome-wide expression of X-linked genes and lead to several useful predictions that could motivate future studies of allele-specific gene expression variation.

  7. Switching the centromeres on and off: epigenetic chromatin alterations provide plasticity in centromere activity stabilizing aberrant dicentric chromosomes.

    Science.gov (United States)

    Sato, Hiroshi; Saitoh, Shigeaki

    2013-12-01

    The kinetochore, which forms on a specific chromosomal locus called the centromere, mediates interactions between the chromosome and the spindle during mitosis and meiosis. Abnormal chromosome rearrangements and/or neocentromere formation can cause the presence of multiple centromeres on a single chromosome, which results in chromosome breakage or cell cycle arrest. Analyses of artificial dicentric chromosomes suggested that the activity of the centromere is regulated epigenetically; on some stably maintained dicentric chromosomes, one of the centromeres no longer functions as a platform for kinetochore formation, although the DNA sequence remains intact. Such epigenetic centromere inactivation occurs in cells of various eukaryotes harbouring 'regional centromeres', such as those of maize, fission yeast and humans, suggesting that the position of the active centromere is determined by epigenetic markers on a chromosome rather than the nucleotide sequence. Our recent findings in fission yeast revealed that epigenetic centromere inactivation consists of two steps: disassembly of the kinetochore initiates inactivation and subsequent heterochromatinization prevents revival of the inactivated centromere. Kinetochore disassembly followed by heterochromatinization is also observed in normal senescent human cells. Thus epigenetic centromere inactivation may not only stabilize abnormally generated dicentric chromosomes, but also be part of an intrinsic mechanism regulating cell proliferation.

  8. Increased sex chromosome expression and epigenetic abnormalities in spermatids from male mice with Y chromosome deletions.

    Science.gov (United States)

    Reynard, Louise N; Turner, James M A

    2009-11-15

    During male meiosis, the X and Y chromosomes are transcriptionally silenced, a process termed meiotic sex chromosome inactivation (MSCI). Recent studies have shown that the sex chromosomes remain substantially transcriptionally repressed after meiosis in round spermatids, but the mechanisms involved in this later repression are poorly understood. Mice with deletions of the Y chromosome long arm (MSYq-) have increased spermatid expression of multicopy X and Y genes, and so represent a model for studying post-meiotic sex chromosome repression. Here, we show that the increase in sex chromosome transcription in spermatids from MSYq- mice affects not only multicopy but also single-copy XY genes, as well as an X-linked reporter gene. This increase in transcription is accompanied by specific changes in the sex chromosome histone code, including almost complete loss of H4K8Ac and reduction of H3K9me3 and CBX1. Together, these data show that an MSYq gene regulates sex chromosome gene expression as well as chromatin remodelling in spermatids.

  9. Uniparental disomy of the entire X chromosome in Turner syndrome patient-specific induced pluripotent stem cells.

    Science.gov (United States)

    Luo, Yumei; Zhu, Detu; Du, Rong; Gong, Yu; Xie, Chun; Xu, Xiangye; Fan, Yong; Yu, Bolan; Sun, Xiaofang; Chen, Yaoyong

    2015-01-01

    The human induced pluripotent stem cell (iPSC) technique promises to provide an unlimited, reliable source of genetically matched pluripotent cells for personalized therapy and disease modeling. Recently, it is observed that cells with ring chromosomes 13 or 17 autonomously correct the defects via compensatory uniparental disomy during cellular reprogramming to iPSCs. This breakthrough finding suggests a potential therapeutic approach to repair large-scale chromosomal aberrations. However, due to the scarceness of ring chromosome samples, the reproducibility of this approach in different individuals is not carefully evaluated yet. Moreover, the underlying mechanism and the applicability to other types of chromosomal aberrations remain unknown. Here we generated iPSCs from four 45,X chorionic villous fibroblast lines and found that only one reprogrammed line acquired 46,XX karyotype via uniparental disomy of the entire X chromosome. The karyotype correction was reproducible in the same cell line by either retroviral or episomal reprogramming. The karyotype-corrected iPSCs were subject to X chromosome inactivation and obtained better colony morphology and higher proliferation rate than other uncorrected ones. Further transcriptomic comparison among the fibroblast lines identified a distinct expression pattern of cell cycle regulators in the uncorrectable ones. These findings demonstrate that the iPSC technique holds the potential to correct X monosomy, but the correction rate is very low, probably due to differential regulation of cell cycle genes between individuals. Our data strongly suggest that more systematic investigations are needed before defining the iPSC technique as a novel means of chromosome therapy.

  10. Correlation of chromosome patterns in human leukemic cells with exposure to chemicals and/or radiation. Comprehensive progress report, July 1991--June 1994

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, J.D.

    1994-06-01

    This comprehensive progress report provides a synopsis of major research accomplishments during the years of 1991-1994, including the technical aspects of the project. The objectives and accomplishments are as follows: 1. Defining the chromosome segments associated with radiation and chemically-induced leukemogenesis (treatment-related acute myeloid leukemia, t-AML); A. Continued genetic analysis of chromosomes 5 and 7, B. Correlation of treatment with balanced and unbalanced translocations. 2. Cloning the breakpoints in balanced translocations in t-AML; A. Clone the t(9;11) and t(11;19) breakpoints, B. Clone the t(3,21)(q26,q22) breakpoint, C. Determine the relationship of these translocations to prior exposure to topoisomerase II inhibitors. 3. Compare the breakpoint junctions in patients who have the same translocations in t-AML and AML de novo. 4. Map the scaffold attachment regions in the genes that are involved in balanced translocations in t-AML. Plans for the continuation of present objectives and possible new objectives in consideration of past results are also provided.

  11. Correlation of chromosome patterns in human leukemic cells with exposure to chemicals and/or radiation. Final report, January 1--December 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, J.D.

    1998-03-01

    It has been clear for the last 15 years that cloning translocation breakpoints in both AML de novo and t-AML would provide the DNA probes required to determine whether the breakpoints in cytogenetically apparently similar translocations were identical at the level of DNA. Therefore the author has pursued an analysis of rearrangements in both types of leukemia simultaneously. She has also cloned and sequenced several translocations in acute lymphoblastic leukemia and in chronic lymphatic leukemia. Recently she cloned the breakpoint in a number of translocations involving chromosome bands 11q23 and 21q22. She has cloned the gene which she called MLL, that is located in 11q23 that is involved in the 6;11, 9;11, and 11;19 translocations that are seen in AML de novo as well as in t-AML. She has evidence that the breakpoint in 11q23 and in the t(9;11) is relatively similar in de novo and secondary AML. In addition, she has cloned the gene at the breakpoint in chromosome 21 in the t(3;21). These studies have provided DNA probes that will be very important for diagnosis and for monitoring the patient`s response to treatment.

  12. Transmission Behavior of B Chromosomes in Prochilodus lineatus (Characiformes, Prochilodontidae).

    Science.gov (United States)

    Penitente, Manolo; Daniel, Sandro N; Senhorini, José A; Foresti, Fausto; Porto-Foresti, Fábio

    2015-01-01

    The population of Prochilodus lineatus found in the Mogi-Guaçu River is karyotypically polymorphic, carrying acrocentric, metacentric, and submetacentric B chromosomes. The analysis of each B chromosome frequency in this species revealed a variation in the distribution pattern, with the metacentric type having the highest frequency (73.30%), followed by submetacentric (25.22%) and acrocentric B chromosomes (1.48%). The transmission pattern of the supernumerary chromosomes was identified by controlled crosses, and it was shown that the acro- and submetacentric B chromosomes have a transmission pattern below the Mendelian rate (kB = 0.333 and kB = 0.385, respectively), but the metacentric variant has a cumulative transmission pattern (kB = 0.587). These results indicate that the acro- and submetacentric B chromosomes are undergoing an extinction process, while the metacentric B chromosomes appear to be accumulating in frequency with each generation.

  13. Evaluating the relationship between spermatogenic silencing of the X chromosome and evolution of the Y chromosome in chimpanzee and human.

    Science.gov (United States)

    Mulugeta Achame, Eskeatnaf; Baarends, Willy M; Gribnau, Joost; Grootegoed, J Anton

    2010-12-14

    Chimpanzees and humans are genetically very similar, with the striking exception of their Y chromosomes, which have diverged tremendously. The male-specific region (MSY), representing the greater part of the Y chromosome, is inherited from father to son in a clonal fashion, with natural selection acting on the MSY as a unit. Positive selection might involve the performance of the MSY in spermatogenesis. Chimpanzees have a highly polygamous mating behavior, so that sperm competition is thought to provide a strong selective force acting on the Y chromosome in the chimpanzee lineage. In consequence of evolution of the heterologous sex chromosomes in mammals, meiotic sex chromosome inactivation (MSCI) results in a transcriptionally silenced XY body in male meiotic prophase, and subsequently also in postmeiotic repression of the sex chromosomes in haploid spermatids. This has evolved to a situation where MSCI has become a prerequisite for spermatogenesis. Here, by analysis of microarray testicular expression data representing a small number of male chimpanzees and men, we obtained information indicating that meiotic and postmeiotic X chromosome silencing might be more effective in chimpanzee than in human spermatogenesis. From this, we suggest that the remarkable reorganization of the chimpanzee Y chromosome, compared to the human Y chromosome, might have an impact on its meiotic interactions with the X chromosome and thereby on X chromosome silencing in spermatogenesis. Further studies will be required to address comparative functional aspects of MSCI in chimpanzee, human, and other placental mammals.

  14. Evaluating the relationship between spermatogenic silencing of the X chromosome and evolution of the Y chromosome in chimpanzee and human.

    Directory of Open Access Journals (Sweden)

    Eskeatnaf Mulugeta Achame

    Full Text Available Chimpanzees and humans are genetically very similar, with the striking exception of their Y chromosomes, which have diverged tremendously. The male-specific region (MSY, representing the greater part of the Y chromosome, is inherited from father to son in a clonal fashion, with natural selection acting on the MSY as a unit. Positive selection might involve the performance of the MSY in spermatogenesis. Chimpanzees have a highly polygamous mating behavior, so that sperm competition is thought to provide a strong selective force acting on the Y chromosome in the chimpanzee lineage. In consequence of evolution of the heterologous sex chromosomes in mammals, meiotic sex chromosome inactivation (MSCI results in a transcriptionally silenced XY body in male meiotic prophase, and subsequently also in postmeiotic repression of the sex chromosomes in haploid spermatids. This has evolved to a situation where MSCI has become a prerequisite for spermatogenesis. Here, by analysis of microarray testicular expression data representing a small number of male chimpanzees and men, we obtained information indicating that meiotic and postmeiotic X chromosome silencing might be more effective in chimpanzee than in human spermatogenesis. From this, we suggest that the remarkable reorganization of the chimpanzee Y chromosome, compared to the human Y chromosome, might have an impact on its meiotic interactions with the X chromosome and thereby on X chromosome silencing in spermatogenesis. Further studies will be required to address comparative functional aspects of MSCI in chimpanzee, human, and other placental mammals.

  15. Chromosomal painting and ZW sex chromosomes differentiation in Characidium (Characiformes, Crenuchidae

    Directory of Open Access Journals (Sweden)

    Artoni Roberto F

    2011-07-01

    Full Text Available Abstract Background The Characidium (a Neotropical fish group have a conserved diploid number (2n = 50, but show remarkable differences among species and populations in relation to sex chromosome systems and location of nucleolus organizer regions (NOR. In this study, we isolated a W-specific probe for the Characidium and characterized six Characidium species/populations using cytogenetic procedures. We analyzed the origin and differentiation of sex and NOR-bearing chromosomes by chromosome painting in populations of Characidium to reveal their evolution, phylogeny, and biogeography. Results A W-specific probe for efficient chromosome painting was isolated by microdissection and degenerate oligonucleotide primed-polymerase chain reaction (DOP-PCR amplification of W chromosomes from C. gomesi. The W probe generated weak signals dispersed on the proto sex chromosomes in C. zebra, dispersed signals in both W and Z chromosomes in C. lauroi and, in C. gomesi populations revealed a proximal site on the long arms of the Z chromosome and the entire W chromosome. All populations showed small terminal W probe sites in some autosomes. The 18S rDNA revealed distinctive patterns for each analyzed species/population with regard to proto sex chromosome, sex chromosome pair, and autosome location. Conclusions The results from dual-color fluorescence in situ hybridization (dual-color FISH using W and 18S rDNA probes allowed us to infer the putative evolutionary pathways for the differentiation of sex chromosomes and NORs, from structural rearrangements in a sex proto-chromosome, followed by gene erosion and heterochromatin amplification, morphological differentiation of the sex chromosomal pair, and NOR transposition, giving rise to the distinctive patterns observed among species/populations of Characidium. Biogeographic isolation and differentiation of sex chromosomes seem to have played a major role in the speciation process in this group of fish.

  16. VHL loss causes spindle misorientation and chromosome instability.

    Science.gov (United States)

    Thoma, Claudio R; Toso, Alberto; Gutbrodt, Katrin L; Reggi, Sabina P; Frew, Ian J; Schraml, Peter; Hergovich, Alexander; Moch, Holger; Meraldi, Patrick; Krek, Wilhelm

    2009-08-01

    Error-free mitosis depends on fidelity-monitoring checkpoint systems that ensure correct temporal and spatial coordination of chromosome segregation by the microtubule spindle apparatus. Defects in these checkpoint systems can lead to genomic instability, an important aspect of tumorigenesis. Here we show that the von Hippel-Lindau (VHL) tumour suppressor protein, pVHL, which is inactivated in hereditary and sporadic forms of renal cell carcinoma, localizes to the mitotic spindle in mammalian cells and its functional inactivation provokes spindle misorientation, spindle checkpoint weakening and chromosomal instability. Spindle misorientation is linked to unstable astral microtubules and is supressed by the restoration of wild-type pVHL in pVHL-deficient cells, but not in naturally-occurring VHL disease mutants that are defective in microtubule stabilization. Impaired spindle checkpoint function and chromosomal instability are the result of reduced Mad2 (mitotic arrest deficient 2) levels actuated by pVHL-inactivation and are rescued by re-expression of either Mad2 or pVHL in VHL-defective cells. An association between VHL inactivation, reduced Mad2 levels and increased aneuploidy was also found in human renal cancer, implying that the newly identified functions of pVHL in promoting proper spindle orientation and chromosomal stability probably contribute to tumour suppression.

  17. Temporal genomic evolution of bird sex chromosomes

    DEFF Research Database (Denmark)

    Wang, Zongji; Zhang, Jilin; Yang, Wei;

    2014-01-01

    BACKGROUND: Sex chromosomes exhibit many unusual patterns in sequence and gene expression relative to autosomes. Birds have evolved a female heterogametic sex system (male ZZ, female ZW), through stepwise suppression of recombination between chrZ and chrW. To address the broad patterns and complex...... driving forces of Z chromosome evolution, we analyze here 45 newly available bird genomes and four species' transcriptomes, over their course of recombination loss between the sex chromosomes. RESULTS: We show Z chromosomes in general have a significantly higher substitution rate in introns and synonymous...... changes with that of introns, between chrZ and autosomes or regions with increasing ages of becoming Z-linked, therefore codon usage bias in birds is probably driven by the mutational bias. On the other hand, Z chromosomes also evolve significantly faster at nonsynonymous sites relative to autosomes...

  18. Normal histone modifications on the inactive X chromosome in ICF and Rett syndrome cells: implications for methyl-CpG binding proteins

    Directory of Open Access Journals (Sweden)

    Canfield Theresa K

    2004-09-01

    Full Text Available Abstract Background In mammals, there is evidence suggesting that methyl-CpG binding proteins may play a significant role in histone modification through their association with modification complexes that can deacetylate and/or methylate nucleosomes in the proximity of methylated DNA. We examined this idea for the X chromosome by studying histone modifications on the X chromosome in normal cells and in cells from patients with ICF syndrome (Immune deficiency, Centromeric region instability, and Facial anomalies syndrome. In normal cells the inactive X has characteristic silencing type histone modification patterns and the CpG islands of genes subject to X inactivation are hypermethylated. In ICF cells, however, genes subject to X inactivation are hypomethylated on the inactive X due to mutations in the DNA methyltransferase (DNMT3B genes. Therefore, if DNA methylation is upstream of histone modification, the histones on the inactive X in ICF cells should not be modified to a silent form. In addition, we determined whether a specific methyl-CpG binding protein, MeCP2, is necessary for the inactive X histone modification pattern by studying Rett syndrome cells which are deficient in MeCP2 function. Results We show here that the inactive X in ICF cells, which appears to be hypomethylated at all CpG islands, exhibits normal histone modification patterns. In addition, in Rett cells with no functional MeCP2 methyl-CpG binding protein, the inactive X also exhibits normal histone modification patterns. Conclusions These data suggest that DNA methylation and the associated methyl-DNA binding proteins may not play a critical role in determining histone modification patterns on the mammalian inactive X chromosome at the sites analyzed.

  19. Absence of Y chromosome in human placental site trophoblastic tumor.

    Science.gov (United States)

    Hui, Pei; Wang, Hanlin L; Chu, Peiguo; Yang, Bin; Huang, Jiaoti; Baergen, Rebecca N; Sklar, Jeffrey; Yang, Ximing J; Soslow, Robert A

    2007-10-01

    Placental site trophoblastic tumor is a neoplasm of extravillous intermediate trophoblast at the implantation site, preceded in the majority of cases by a female gestational event. Our pilot investigation suggested that the development of this tumor might require a paternally derived X chromosome and the absence of a Y chromosome. Twenty cases of placental site trophoblastic tumor were included in this study. Genotyping at 15 polymorphic loci and one sex determination locus was performed by multiplex PCR followed by capillary electrophoresis. X chromosome polymorphisms were determined by PCR amplification of exon 1 of the human androgen receptor gene using primers flanking the polymorphic CAG repeats within this region. Genotyping at 15 polymorphic loci was informative and paternal alleles were present in all tumors, confirming the trophoblastic origin of the tumors. The presence of an X chromosome and the absence of a Y chromosome were observed in all tumors. Among 13 cases in which analysis of the X chromosome polymorphism was informative, all but one demonstrated at least two X alleles and seven cases showed one identifiable paternal X allele. These results confirm a unique pathogenetic mechanism in placental site trophoblastic tumor, involving an exclusion of the Y chromosome from the genome and, therefore, a tumor arising from the trophectoderm of a female conceptus. As epigenetic regulations of imprinting during X chromosome inactivation are of significant biological implications, placental site trophoblastic tumor may provide an important model for studying the sex chromosome biology and the proliferative advantage conferred by the paternal X chromosome.

  20. Molecular cloning, genomic organization, chromosome mapping, tissues expression pattern and identification of a novel splicing variant of porcine CIDEb gene.

    Science.gov (United States)

    Li, YanHua; Li, AiHua; Yang, Z Q

    2016-09-09

    Cell death-inducing DNA fragmentation factor-α-like effector b (CIDEb) is a member of the CIDE family of apoptosis-inducing factors, CIDEa and CIDEc have been reported to be Lipid droplets (LDs)-associated proteins that promote atypical LD fusion in adipocytes, and responsible for liver steatosis under fasting and obese conditions, whereas CIDEb promotes lipid storage under normal diet conditions [1], and promotes the formation of triacylglyceride-enriched VLDL particles in hepatocytes [2]. Here, we report the gene cloning, chromosome mapping, tissue distribution, genetic expression analysis, and identification of a novel splicing variant of the porcine CIDEb gene. Sequence analysis shows that the open reading frame of the normal porcine CIDEb isoform covers 660bp and encodes a 219-amino acid polypeptide, whereas its alternative splicing variant encodes a 142-amino acid polypeptide truncated at the fourth exon and comprised of the CIDE-N domain and part of the CIDE-C domain. The deduced amino acid sequence of normal porcine CIDEb shows an 85.8% similarity to the human protein and 80.0% to the mouse protein. The CIDEb genomic sequence spans approximately 6KB comprised of five exons and four introns. Radiation hybrid mapping demonstrated that porcine CIDEb is located at chromosome 7q21 and at a distance of 57cR from the most significantly linked marker, S0334, regions that are syntenic with the corresponding region in the human genome. Tissue expression analysis indicated that normal CIDEb mRNA is ubiquitously expressed in many porcine tissues. It was highly expressed in white adipose tissue and was observed at relatively high levels in the liver, lung, small intestine, lymphatic tissue and brain. The normal version of CIDEb was the predominant form in all tested tissues, whereas the splicing variant was expressed at low levels in all examined tissues except the lymphatic tissue. Furthermore, genetic expression analysis indicated that CIDEb mRNA levels were

  1. 散发Rett综合征患儿新生MECP2突变亲源鉴定和X染色体失活15例分析%Analysis of the parental origin of de novo MECP2 mutations and X chromosome inactivation in fifteen sporadic cases with Rett syndrome

    Institute of Scientific and Technical Information of China (English)

    朱兴旺; 潘虹; 李美蓉; 包新华; 张晶晶; 吴希如

    2009-01-01

    Objective Rett syndrome (RTT) is a neurodevelopmental disorder occurring almost exclusively in females as sporadic cases due to de novo mutations in the methyl-CpG-binding protein 2 gene ( MECP2 ). Familial cases of RTT are rare and are due to X-chromosomal inheritance from a cartier mother. Recently, DNA mutations in the MECP2 have been detected in approximately 84.7% of patients with RTT in China. To explain the sex-limited expression of RTT, it has been suggested that de novo X-linked mutations oecttr exclusively in male germ cells resulting therefore only in affected daughters. To test this hypothesis, we have analyzed the parental origin of mutations and the XCI status in 15 sporadic cases with RTT due to MECP2 molecular defects. Methods Allele-specific PCR was performed to amplify a fragment including the position of the mutation. The allele-specific PCR products were sequenced to determine which haplotype contained the mutation. It was then possible to determine the parent of origin by genotyping the single nucleotide polymorphism (SNP) in the parents. The degree of XCI and its direction relative to the X chromosome parent of origin were measured in DNA prepared from peripheral blood leucocytes by analyzing CAG repeat polymorphism in the androgen receptor gene (AR). Results Except for 2 cases who had a frameshifi mutation; all the remaining 13 cases had a C→T transition mutation. Paternal origin has been determined in all cases with the C→T transition mutation. For the two frameshift mutations, paternal origin has been determined in one case and maternal origin in the other. The frequency of male germ-line transmission in mutations is 93.3%. Except for 2 cases who were homozygotic at the AR locus, of the remaining 13 cases, 8 cases had a random XCI pattern; the other five cases had a skewed XCI pattern and they favor expression of the maternal origin allele. Conclusion De novo mutations in sporadic RTr occur almost exclusively on the paternally derived X

  2. Neo-sex chromosomes in the black muntjac recapitulate incipient evolution of mammalian sex chromosomes

    DEFF Research Database (Denmark)

    Zhou, Qi; Wang, Jun; Huang, Ling

    2008-01-01

    SNX22 abolished a microRNA target site. Finally, expression analyses revealed complex patterns of expression divergence between neo-Y and neo-X alleles. CONCLUSION: The nascent neo-sex chromosome system of black muntjacs is a valuable model in which to study the evolution of sex chromosomes in mammals......BACKGROUND: The regular mammalian X and Y chromosomes diverged from each other at least 166 to 148 million years ago, leaving few traces of their early evolution, including degeneration of the Y chromosome and evolution of dosage compensation. RESULTS: We studied the intriguing case of black...... muntjac, in which a recent X-autosome fusion and a subsequent large autosomal inversion within just the past 0.5 million years have led to inheritance patterns identical to the traditional X-Y (neo-sex chromosomes). We compared patterns of genome evolution in 35-kilobase noncoding regions and 23 gene...

  3. Role of androgen receptor CAG repeat polymorphism and X-inactivation in the manifestation of recurrent spontaneous abortions in Indian women.

    Directory of Open Access Journals (Sweden)

    Meka Aruna

    Full Text Available The aim of the present study was to investigate the role of CAG repeat polymorphism and X-chromosome Inactivation (XCI pattern in Recurrent Spontaneous Abortions among Indian women which has not been hitherto explored. 117 RSA cases and 224 Controls were included in the study. Cases were recruited from two different hospitals--Lakshmi Fertility Clinic, Nellore and Fernandez Maternity Hospital, Hyderabad. Controls were roughly matched for age, ethnicity and socioeconomic status. The CAG repeats of the Androgen Receptor gene were genotyped using a PCR-based assay and were analysed using the GeneMapper software to determine the CAG repeat length. XCI analysis was also carried out to assess the inactivation percentages. RSA cases had a significantly greater frequency of allele sizes in the polymorphic range above 19 repeats (p = 0.006, which is the median value of the controls, and in the biallelic mean range above 21 repeats (p = 0.002. We found no evidence of abnormal incidence of skewed X-inactivation. We conclude that longer CAG repeat lengths are associated with increased odds for RSA with statistical power estimated to be ∼90%.

  4. ASAR15, A cis-acting locus that controls chromosome-wide replication timing and stability of human chromosome 15.

    Directory of Open Access Journals (Sweden)

    Nathan Donley

    2015-01-01

    Full Text Available DNA replication initiates at multiple sites along each mammalian chromosome at different times during each S phase, following a temporal replication program. We have used a Cre/loxP-based strategy to identify cis-acting elements that control this replication-timing program on individual human chromosomes. In this report, we show that rearrangements at a complex locus at chromosome 15q24.3 result in delayed replication and structural instability of human chromosome 15. Characterization of this locus identified long, RNA transcripts that are retained in the nucleus and form a "cloud" on one homolog of chromosome 15. We also found that this locus displays asynchronous replication that is coordinated with other random monoallelic genes on chromosome 15. We have named this locus ASynchronous replication and Autosomal RNA on chromosome 15, or ASAR15. Previously, we found that disruption of the ASAR6 lincRNA gene results in delayed replication, delayed mitotic condensation and structural instability of human chromosome 6. Previous studies in the mouse found that deletion of the Xist gene, from the X chromosome in adult somatic cells, results in a delayed replication and instability phenotype that is indistinguishable from the phenotype caused by disruption of either ASAR6 or ASAR15. In addition, delayed replication and chromosome instability were detected following structural rearrangement of many different human or mouse chromosomes. These observations suggest that all mammalian chromosomes contain similar cis-acting loci. Thus, under this scenario, all mammalian chromosomes contain four distinct types of essential cis-acting elements: origins, telomeres, centromeres and "inactivation/stability centers", all functioning to promote proper replication, segregation and structural stability of each chromosome.

  5. Genotype and phenotype in Klinefelter syndrome - impact of androgen receptor polymorphism and skewed X inactivation

    DEFF Research Database (Denmark)

    Bojesen, A; Hertz, J M; Gravholt, C H

    2011-01-01

    The phenotypic variation of Klinefelter syndrome (KS) is wide and may by caused by various genetic and epigenetic effects. Skewed inactivation of the supra-numerical X chromosome and polymorphism in the androgen receptor (AR) have been suggested as plausible causes. We wanted to describe X...

  6. Telomere disruption results in non-random formation of de novo dicentric chromosomes involving acrocentric human chromosomes.

    Directory of Open Access Journals (Sweden)

    Kaitlin M Stimpson

    2010-08-01

    Full Text Available Genome rearrangement often produces chromosomes with two centromeres (dicentrics that are inherently unstable because of bridge formation and breakage during cell division. However, mammalian dicentrics, and particularly those in humans, can be quite stable, usually because one centromere is functionally silenced. Molecular mechanisms of centromere inactivation are poorly understood since there are few systems to experimentally create dicentric human chromosomes. Here, we describe a human cell culture model that enriches for de novo dicentrics. We demonstrate that transient disruption of human telomere structure non-randomly produces dicentric fusions involving acrocentric chromosomes. The induced dicentrics vary in structure near fusion breakpoints and like naturally-occurring dicentrics, exhibit various inter-centromeric distances. Many functional dicentrics persist for months after formation. Even those with distantly spaced centromeres remain functionally dicentric for 20 cell generations. Other dicentrics within the population reflect centromere inactivation. In some cases, centromere inactivation occurs by an apparently epigenetic mechanism. In other dicentrics, the size of the alpha-satellite DNA array associated with CENP-A is reduced compared to the same array before dicentric formation. Extra-chromosomal fragments that contained CENP-A often appear in the same cells as dicentrics. Some of these fragments are derived from the same alpha-satellite DNA array as inactivated centromeres. Our results indicate that dicentric human chromosomes undergo alternative fates after formation. Many retain two active centromeres and are stable through multiple cell divisions. Others undergo centromere inactivation. This event occurs within a broad temporal window and can involve deletion of chromatin that marks the locus as a site for CENP-A maintenance/replenishment.

  7. Telomere disruption results in non-random formation of de novo dicentric chromosomes involving acrocentric human chromosomes.

    Science.gov (United States)

    Stimpson, Kaitlin M; Song, Ihn Young; Jauch, Anna; Holtgreve-Grez, Heidi; Hayden, Karen E; Bridger, Joanna M; Sullivan, Beth A

    2010-08-12

    Genome rearrangement often produces chromosomes with two centromeres (dicentrics) that are inherently unstable because of bridge formation and breakage during cell division. However, mammalian dicentrics, and particularly those in humans, can be quite stable, usually because one centromere is functionally silenced. Molecular mechanisms of centromere inactivation are poorly understood since there are few systems to experimentally create dicentric human chromosomes. Here, we describe a human cell culture model that enriches for de novo dicentrics. We demonstrate that transient disruption of human telomere structure non-randomly produces dicentric fusions involving acrocentric chromosomes. The induced dicentrics vary in structure near fusion breakpoints and like naturally-occurring dicentrics, exhibit various inter-centromeric distances. Many functional dicentrics persist for months after formation. Even those with distantly spaced centromeres remain functionally dicentric for 20 cell generations. Other dicentrics within the population reflect centromere inactivation. In some cases, centromere inactivation occurs by an apparently epigenetic mechanism. In other dicentrics, the size of the alpha-satellite DNA array associated with CENP-A is reduced compared to the same array before dicentric formation. Extra-chromosomal fragments that contained CENP-A often appear in the same cells as dicentrics. Some of these fragments are derived from the same alpha-satellite DNA array as inactivated centromeres. Our results indicate that dicentric human chromosomes undergo alternative fates after formation. Many retain two active centromeres and are stable through multiple cell divisions. Others undergo centromere inactivation. This event occurs within a broad temporal window and can involve deletion of chromatin that marks the locus as a site for CENP-A maintenance/replenishment.

  8. MAX inactivation is an early event in GIST development that regulates p16 and cell proliferation

    Science.gov (United States)

    Schaefer, Inga-Marie; Wang, Yuexiang; Liang, Cher-wei; Bahri, Nacef; Quattrone, Anna; Doyle, Leona; Mariño-Enríquez, Adrian; Lauria, Alexandra; Zhu, Meijun; Debiec-Rychter, Maria; Grunewald, Susanne; Hechtman, Jaclyn F.; Dufresne, Armelle; Antonescu, Cristina R.; Beadling, Carol; Sicinska, Ewa T.; van de Rijn, Matt; Demetri, George D.; Ladanyi, Marc; Corless, Christopher L.; Heinrich, Michael C.; Raut, Chandrajit P.; Bauer, Sebastian; Fletcher, Jonathan A.

    2017-01-01

    KIT, PDGFRA, NF1 and SDH mutations are alternate initiating events, fostering hyperplasia in gastrointestinal stromal tumours (GISTs), and additional genetic alterations are required for progression to malignancy. The most frequent secondary alteration, demonstrated in ∼70% of GISTs, is chromosome 14q deletion. Here we report hemizygous or homozygous inactivating mutations of the chromosome 14q MAX gene in 16 of 76 GISTs (21%). We find MAX mutations in 17% and 50% of sporadic and NF1-syndromic GISTs, respectively, and we find loss of MAX protein expression in 48% and 90% of sporadic and NF1-syndromic GISTs, respectively, and in three of eight micro-GISTs, which are early GISTs. MAX genomic inactivation is associated with p16 silencing in the absence of p16 coding sequence deletion and MAX induction restores p16 expression and inhibits GIST proliferation. Hence, MAX inactivation is a common event in GIST progression, fostering cell cycle activity in early GISTs. PMID:28270683

  9. A natural inactivating mutation in the CovS component of the CovRS regulatory operon in a pattern D Streptococcal pyogenes strain influences virulence-associated genes.

    Science.gov (United States)

    Liang, Zhong; Zhang, Yueling; Agrahari, Garima; Chandrahas, Vishwanatha; Glinton, Kristofor; Donahue, Deborah L; Balsara, Rashna D; Ploplis, Victoria A; Castellino, Francis J

    2013-03-01

    A skin-tropic invasive group A Streptococcus pyogenes (GAS) strain, AP53, contains a natural inactivating mutation in the covS gene (covS(M)) of the two-component responder (CovR)/sensor (CovS) gene regulatory system. The effects of this mutation on specific GAS virulence determinants have been assessed, with emphasis on expression of the extracellular protease, streptococcal pyrogenic exotoxin B (SpeB), capsular hyaluronic acid, and proteins that allow host plasmin assembly on the bacterial surface, viz. a high affinity plasminogen (Pg)/plasmin receptor, Pg-binding group A streptococcal M protein (PAM), and the human Pg activator streptokinase. To further illuminate mechanisms of the functioning of CovRS in the virulence of AP53, two AP53 isogenic strains were generated, one in which the natural covS(M) gene was mutated to WT-covS (AP53/covS(WT)) and a strain that contained an inactivated covR gene (AP53/ΔcovR). Two additional strains that do not contain PAM, viz. WT-NS931 and NS931/covS(M), were also employed. SpeB was not measurably expressed in strains containing covR(WT)/covS(M), whereas in strains with natural or engineered covR(WT)/covS(WT), SpeB expression was highly up-regulated. Alternatively, capsule synthesis via the hasABC operon was enhanced in strain AP53/covS(M), whereas streptokinase expression was only slightly affected by the covS inactivation. PAM expression was not substantially influenced by the covS mutation, suggesting that covRS had minimal effects on the mga regulon that controls PAM expression. These results demonstrate that a covS inactivation results in virulence gene alterations and also suggest that the CovR phosphorylation needed for gene up- or down-regulation can occur by alternative pathways to CovS kinase.

  10. Origin and evolution of the long non-coding genes in the X-inactivation center.

    Science.gov (United States)

    Romito, Antonio; Rougeulle, Claire

    2011-11-01

    Random X chromosome inactivation (XCI), the eutherian mechanism of X-linked gene dosage compensation, is controlled by a cis-acting locus termed the X-inactivation center (Xic). One of the striking features that characterize the Xic landscape is the abundance of loci transcribing non-coding RNAs (ncRNAs), including Xist, the master regulator of the inactivation process. Recent comparative genomic analyses have depicted the evolutionary scenario behind the origin of the X-inactivation center, revealing that this locus evolved from a region harboring protein-coding genes. During mammalian radiation, this ancestral protein-coding region was disrupted in the marsupial group, whilst it provided in eutherian lineage the starting material for the non-translated RNAs of the X-inactivation center. The emergence of non-coding genes occurred by a dual mechanism involving loss of protein-coding function of the pre-existing genes and integration of different classes of mobile elements, some of which modeled the structure and sequence of the non-coding genes in a species-specific manner. The rising genes started to produce transcripts that acquired function in regulating the epigenetic status of the X chromosome, as shown for Xist, its antisense Tsix, Jpx, and recently suggested for Ftx. Thus, the appearance of the Xic, which occurred after the divergence between eutherians and marsupials, was the basis for the evolution of random X inactivation as a strategy to achieve dosage compensation.

  11. Identification of genes escaping X inactivation by allelic expression analysis in a novel hybrid mouse model.

    Science.gov (United States)

    Berletch, Joel B; Ma, Wenxiu; Yang, Fan; Shendure, Jay; Noble, William S; Disteche, Christine M; Deng, Xinxian

    2015-12-01

    X chromosome inactivation (XCI) is a female-specific mechanism that serves to balance gene dosage between the sexes whereby one X chromosome in females is inactivated during early development. Despite this silencing, a small portion of genes escape inactivation and remain expressed from the inactive X (Xi). Little is known about the distribution of escape from XCI in different tissues in vivo and about the mechanisms that control tissue-specific differences. Using a new binomial model in conjunction with a mouse model with identifiable alleles and skewed X inactivation we are able to survey genes that escape XCI in vivo. We show that escape from X inactivation can be a common feature of some genes, whereas others escape in a tissue specific manner. Furthermore, we characterize the chromatin environment of escape genes and show that expression from the Xi correlates with factors associated with open chromatin and that CTCF co-localizes with escape genes. Here, we provide a detailed description of the experimental design and data analysis pipeline we used to assay allele-specific expression and epigenetic characteristics of genes escaping X inactivation. The data is publicly available through the GEO database under ascension numbers GSM1014171, GSE44255, and GSE59779. Interpretation and discussion of these data are included in a previously published study (Berletch et al., 2015) [1].

  12. Undetected sex chromosome aneuploidy by chromosomal microarray.

    Science.gov (United States)

    Markus-Bustani, Keren; Yaron, Yuval; Goldstein, Myriam; Orr-Urtreger, Avi; Ben-Shachar, Shay

    2012-11-01

    We report on a case of a female fetus found to be mosaic for Turner syndrome (45,X) and trisomy X (47,XXX). Chromosomal microarray analysis (CMA) failed to detect the aneuploidy because of a normal average dosage of the X chromosome. This case represents an unusual instance in which CMA may not detect chromosomal aberrations. Such a possibility should be taken into consideration in similar cases where CMA is used in a clinical setting.

  13. Karyotype evolution in apomictic Boechera and the origin of the aberrant chromosomes.

    Science.gov (United States)

    Mandáková, Terezie; Schranz, M Eric; Sharbel, Timothy F; de Jong, Hans; Lysak, Martin A

    2015-06-01

    Chromosome rearrangements may result in both decrease and increase of chromosome numbers. Here we have used comparative chromosome painting (CCP) to reconstruct the pathways of descending and ascending dysploidy in the genus Boechera (tribe Boechereae, Brassicaceae). We describe the origin and structure of three Boechera genomes and establish the origin of the previously described aberrant Het and Del chromosomes found in Boechera apomicts with euploid (2n = 14) and aneuploid (2n = 15) chromosome number. CCP analysis allowed us to reconstruct the origin of seven chromosomes in sexual B. stricta and apomictic B. divaricarpa from the ancestral karyotype (n = 8) of Brassicaceae lineage I. Whereas three chromosomes (BS4, BS6, and BS7) retained their ancestral structure, five chromosomes were reshuffled by reciprocal translocations to form chromosomes BS1-BS3 and BS5. The reduction of the chromosome number (from x = 8 to x = 7) was accomplished through the inactivation of a paleocentromere on chromosome BS5. In apomictic 2n = 14 plants, CCP identifies the largely heterochromatic chromosome (Het) being one of the BS1 homologues with the expansion of pericentromeric heterochromatin. In apomictic B. polyantha (2n = 15), the Het has undergone a centric fission resulting in two smaller chromosomes - the submetacentric Het' and telocentric Del. Here we show that new chromosomes can be formed by a centric fission and can be fixed in populations due to the apomictic mode of reproduction.

  14. Cell inactivation by diverse ions along their tracks

    CERN Document Server

    Kundrát, P; Hromcikova, H; Kundrat, Pavel; Lokajicek, Milos; Hromcikova, Hana

    2004-01-01

    Irradiation of cell monolayers by monoenergetic ions has made it possible to establish survival curves at individual values of linear energy transfer. The two-step model of radiobiological mechanism proposed recently by Judas and Lokajicek (Judas L., Lokajicek M., 2001: Cell inactivation by ionizing particles and the shapes of survival curves. J. Theor. Biol. 210 (1), 15-21., doi:10.1006/jtbi.2001.2283) has then enabled to show that some significant deviations from the generally used linear-quadratic model should exist at higher values of linear energy transfer, which has been also demonstrated experimentally. However, the new model has been expressed in the form being applicable rightfully to low-dose parts of survival curves only. It has been now reformulated to be applicable in analyses of whole survival curves. Inactivation probabilities after different numbers of particles traversing cell nuclei (chromosomal systems) may be then derived from experimental data. Analyses of published data obtained in irrad...

  15. Loss of pRB causes centromere dysfunction and chromosomal instability.

    Science.gov (United States)

    Manning, Amity L; Longworth, Michelle S; Dyson, Nicholas J

    2010-07-01

    Chromosome instability (CIN) is a common feature of tumor cells. By monitoring chromosome segregation, we show that depletion of the retinoblastoma protein (pRB) causes rates of missegregation comparable with those seen in CIN tumor cells. The retinoblastoma tumor suppressor is frequently inactivated in human cancers and is best known for its regulation of the G1/S-phase transition. Recent studies have shown that pRB inactivation also slows mitotic progression and promotes aneuploidy, but reasons for these phenotypes are not well understood. Here we describe the underlying mitotic defects of pRB-deficient cells that cause chromosome missegregation. Analysis of mitotic cells reveals that pRB depletion compromises centromeric localization of CAP-D3/condensin II and chromosome cohesion, leading to an increase in intercentromeric distance and deformation of centromeric structure. These defects promote merotelic attachment, resulting in failure of chromosome congression and an increased propensity for lagging chromosomes following mitotic delay. While complete loss of centromere function or chromosome cohesion would have catastrophic consequences, these more moderate defects allow pRB-deficient cells to proliferate but undermine the fidelity of mitosis, leading to whole-chromosome gains and losses. These observations explain an important consequence of RB1 inactivation, and suggest that subtle defects in centromere function are a frequent source of merotely and CIN in cancer.

  16. Influenza Vaccine, Inactivated or Recombinant

    Science.gov (United States)

    ... die from flu, and many more are hospitalized.Flu vaccine can:keep you from getting flu, make flu ... inactivated or recombinant influenza vaccine?A dose of flu vaccine is recommended every flu season. Children 6 months ...

  17. Jarid2 Is Implicated in the Initial Xist-Induced Targeting of PRC2 to the Inactive X Chromosome

    DEFF Research Database (Denmark)

    da Rocha, Simão Teixeira; Boeva, Valentina; Escamilla-Del-Arenal, Martin;

    2014-01-01

    During X chromosome inactivation (XCI), the Polycomb Repressive Complex 2 (PRC2) is thought to participate in the early maintenance of the inactive state. Although Xist RNA is essential for the recruitment of PRC2 to the X chromosome, the precise mechanism remains unclear. Here, we demonstrate th...

  18. Chromosome Disorder Outreach

    Science.gov (United States)

    ... BLOG Join Us Donate You are not alone. Chromosome Disorder Outreach, Inc. is a non-profit organization, ... Support For all those diagnosed with any rare chromosome disorder. Since 1992, CDO has supported the parents ...

  19. The DNA sequence of the human X chromosome.

    Science.gov (United States)

    Ross, Mark T; Grafham, Darren V; Coffey, Alison J; Scherer, Steven; McLay, Kirsten; Muzny, Donna; Platzer, Matthias; Howell, Gareth R; Burrows, Christine; Bird, Christine P; Frankish, Adam; Lovell, Frances L; Howe, Kevin L; Ashurst, Jennifer L; Fulton, Robert S; Sudbrak, Ralf; Wen, Gaiping; Jones, Matthew C; Hurles, Matthew E; Andrews, T Daniel; Scott, Carol E; Searle, Stephen; Ramser, Juliane; Whittaker, Adam; Deadman, Rebecca; Carter, Nigel P; Hunt, Sarah E; Chen, Rui; Cree, Andrew; Gunaratne, Preethi; Havlak, Paul; Hodgson, Anne; Metzker, Michael L; Richards, Stephen; Scott, Graham; Steffen, David; Sodergren, Erica; Wheeler, David A; Worley, Kim C; Ainscough, Rachael; Ambrose, Kerrie D; Ansari-Lari, M Ali; Aradhya, Swaroop; Ashwell, Robert I S; Babbage, Anne K; Bagguley, Claire L; Ballabio, Andrea; Banerjee, Ruby; Barker, Gary E; Barlow, Karen F; Barrett, Ian P; Bates, Karen N; Beare, David M; Beasley, Helen; Beasley, Oliver; Beck, Alfred; Bethel, Graeme; Blechschmidt, Karin; Brady, Nicola; Bray-Allen, Sarah; Bridgeman, Anne M; Brown, Andrew J; Brown, Mary J; Bonnin, David; Bruford, Elspeth A; Buhay, Christian; Burch, Paula; Burford, Deborah; Burgess, Joanne; Burrill, Wayne; Burton, John; Bye, Jackie M; Carder, Carol; Carrel, Laura; Chako, Joseph; Chapman, Joanne C; Chavez, Dean; Chen, Ellson; Chen, Guan; Chen, Yuan; Chen, Zhijian; Chinault, Craig; Ciccodicola, Alfredo; Clark, Sue Y; Clarke, Graham; Clee, Chris M; Clegg, Sheila; Clerc-Blankenburg, Kerstin; Clifford, Karen; Cobley, Vicky; Cole, Charlotte G; Conquer, Jen S; Corby, Nicole; Connor, Richard E; David, Robert; Davies, Joy; Davis, Clay; Davis, John; Delgado, Oliver; Deshazo, Denise; Dhami, Pawandeep; Ding, Yan; Dinh, Huyen; Dodsworth, Steve; Draper, Heather; Dugan-Rocha, Shannon; Dunham, Andrew; Dunn, Matthew; Durbin, K James; Dutta, Ireena; Eades, Tamsin; Ellwood, Matthew; Emery-Cohen, Alexandra; Errington, Helen; Evans, Kathryn L; Faulkner, Louisa; Francis, Fiona; Frankland, John; Fraser, Audrey E; Galgoczy, Petra; Gilbert, James; Gill, Rachel; Glöckner, Gernot; Gregory, Simon G; Gribble, Susan; Griffiths, Coline; Grocock, Russell; Gu, Yanghong; Gwilliam, Rhian; Hamilton, Cerissa; Hart, Elizabeth A; Hawes, Alicia; Heath, Paul D; Heitmann, Katja; Hennig, Steffen; Hernandez, Judith; Hinzmann, Bernd; Ho, Sarah; Hoffs, Michael; Howden, Phillip J; Huckle, Elizabeth J; Hume, Jennifer; Hunt, Paul J; Hunt, Adrienne R; Isherwood, Judith; Jacob, Leni; Johnson, David; Jones, Sally; de Jong, Pieter J; Joseph, Shirin S; Keenan, Stephen; Kelly, Susan; Kershaw, Joanne K; Khan, Ziad; Kioschis, Petra; Klages, Sven; Knights, Andrew J; Kosiura, Anna; Kovar-Smith, Christie; Laird, Gavin K; Langford, Cordelia; Lawlor, Stephanie; Leversha, Margaret; Lewis, Lora; Liu, Wen; Lloyd, Christine; Lloyd, David M; Loulseged, Hermela; Loveland, Jane E; Lovell, Jamieson D; Lozado, Ryan; Lu, Jing; Lyne, Rachael; Ma, Jie; Maheshwari, Manjula; Matthews, Lucy H; McDowall, Jennifer; McLaren, Stuart; McMurray, Amanda; Meidl, Patrick; Meitinger, Thomas; Milne, Sarah; Miner, George; Mistry, Shailesh L; Morgan, Margaret; Morris, Sidney; Müller, Ines; Mullikin, James C; Nguyen, Ngoc; Nordsiek, Gabriele; Nyakatura, Gerald; O'Dell, Christopher N; Okwuonu, Geoffery; Palmer, Sophie; Pandian, Richard; Parker, David; Parrish, Julia; Pasternak, Shiran; Patel, Dina; Pearce, Alex V; Pearson, Danita M; Pelan, Sarah E; Perez, Lesette; Porter, Keith M; Ramsey, Yvonne; Reichwald, Kathrin; Rhodes, Susan; Ridler, Kerry A; Schlessinger, David; Schueler, Mary G; Sehra, Harminder K; Shaw-Smith, Charles; Shen, Hua; Sheridan, Elizabeth M; Shownkeen, Ratna; Skuce, Carl D; Smith, Michelle L; Sotheran, Elizabeth C; Steingruber, Helen E; Steward, Charles A; Storey, Roy; Swann, R Mark; Swarbreck, David; Tabor, Paul E; Taudien, Stefan; Taylor, Tineace; Teague, Brian; Thomas, Karen; Thorpe, Andrea; Timms, Kirsten; Tracey, Alan; Trevanion, Steve; Tromans, Anthony C; d'Urso, Michele; Verduzco, Daniel; Villasana, Donna; Waldron, Lenee; Wall, Melanie; Wang, Qiaoyan; Warren, James; Warry, Georgina L; Wei, Xuehong; West, Anthony; Whitehead, Siobhan L; Whiteley, Mathew N; Wilkinson, Jane E; Willey, David L; Williams, Gabrielle; Williams, Leanne; Williamson, Angela; Williamson, Helen; Wilming, Laurens; Woodmansey, Rebecca L; Wray, Paul W; Yen, Jennifer; Zhang, Jingkun; Zhou, Jianling; Zoghbi, Huda; Zorilla, Sara; Buck, David; Reinhardt, Richard; Poustka, Annemarie; Rosenthal, André; Lehrach, Hans; Meindl, Alfons; Minx, Patrick J; Hillier, Ladeana W; Willard, Huntington F; Wilson, Richard K; Waterston, Robert H; Rice, Catherine M; Vaudin, Mark; Coulson, Alan; Nelson, David L; Weinstock, George; Sulston, John E; Durbin, Richard; Hubbard, Tim; Gibbs, Richard A; Beck, Stephan; Rogers, Jane; Bentley, David R

    2005-03-17

    The human X chromosome has a unique biology that was shaped by its evolution as the sex chromosome shared by males and females. We have determined 99.3% of the euchromatic sequence of the X chromosome. Our analysis illustrates the autosomal origin of the mammalian sex chromosomes, the stepwise process that led to the progressive loss of recombination between X and Y, and the extent of subsequent degradation of the Y chromosome. LINE1 repeat elements cover one-third of the X chromosome, with a distribution that is consistent with their proposed role as way stations in the process of X-chromosome inactivation. We found 1,098 genes in the sequence, of which 99 encode proteins expressed in testis and in various tumour types. A disproportionately high number of mendelian diseases are documented for the X chromosome. Of this number, 168 have been explained by mutations in 113 X-linked genes, which in many cases were characterized with the aid of the DNA sequence.

  20. Chromosome painting in plants.

    NARCIS (Netherlands)

    Schubert, I.; Fransz, P.F.; Fuchs, J.; Jong, de J.H.

    2001-01-01

    The current 'state-of-art' as to chromosome painting in plants is reviewed. We define different situations described as painting so far: i) Genomic in situ hybridisation (GISH) with total genomic DNA to distinguish alien chromosomes on the basis of divergent dispersed repeats, ii) 'Chromosomal in si

  1. ZEBRAFISH CHROMOSOME-BANDING

    NARCIS (Netherlands)

    PIJNACKER, LP; FERWERDA, MA

    1995-01-01

    Banding techniques were carried out on metaphase chromosomes of zebrafish (Danio rerio) embryos. The karyotypes with the longest chromosomes consist of 12 metacentrics, 26 submetacentrics, and 12 subtelocentrics (2n = 50). All centromeres are C-band positive. Eight chromosomes have a pericentric C-b

  2. Inactivation of bacteria in sewage sludge by gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Pandya, G.A.; Kapila, S.; Kelkar, V.B.; Negi, S.; Modi, V.V.

    1987-01-01

    The survival of certain bacterial cultures suspended in sewage sludge and exposed to gamma-radiation was studied. The inactivation patterns of most of the organisms were significantly different when irradiation was performed using sewage samples collected in the summer and monsoon seasons. The summer sample collected from the anaerobic digester afforded significant protection to both Gram negative and Gram positive organisms. This was evident by the increase in dose required to bring about a 6 log cycle reduction in viable count of the bacterial cultures, when suspended in sewage samples instead of phosphate buffer. The observations made using monsoon digester samples were quite different. This sewage sludge greatly enhanced inactivation by gamma-radiation in most cases. The effects of certain chemicals on the inactivation patterns of two organisms - Salmonella typhi and Shigella flexneri - were examined. Arsenate, mercury and lead salts sensitised S. typhi, while barium acetate and sodium sulphide protected this culture against gamma-radiation. In the case of Sh. flexneri, barium acetate and iodacetamide proved to be radioprotectors. The effects of some chemicals on the inactivation pattern of Sh. flexneri cells irradiated in sludge are also discussed.

  3. An evaluation of the performance of HapMap SNP data in a Shanghai Chinese population: Analyses of allele frequency, linkage disequilibrium pattern and tagging SNPs transferability on chromosome 1q21-q25

    Directory of Open Access Journals (Sweden)

    Wang Jie

    2008-02-01

    Full Text Available Abstract Background The HapMap project aimed to catalog millions of common single nucleotide polymorphisms (SNPs in the human genome in four major populations, in order to facilitate association studies of complex diseases. To examine the transferability of Han Chinese in Beijing HapMap data to the Southern Han Chinese in Shanghai, we performed comparative analyses between genotypes from over 4,500 SNPs in a 21 Mb region on chromosome 1q21-q25 in 80 unrelated Shanghai Chinese and 45 HapMap Chinese data. Results Three thousand and forty-two SNPs were analyzed after removal of SNPs that failed quality control and those not in the HapMap panel. We compared the allele frequency distributions, linkage disequilibrium patterns, haplotype frequency distributions and tagging SNP sets transferability between the HapMap population and Shanghai Chinese population. Among the four HapMap populations, Beijing Chinese showed the best correlation with Shanghai population on allele frequencies, linkage disequilibrium and haplotype frequencies. Tagging SNP sets selected from four HapMap populations at different thresholds were evaluated in the Shanghai sample. Under the threshold of r2 equal to 0.8 or 0.5, both HapMap Chinese and Japanese data showed better coverage and tagging efficiency than Caucasian and African data. Conclusion Our study supported the applicability of HapMap Beijing Chinese SNP data to the study of complex diseases among southern Chinese population.

  4. Chromosome Territory Modeller and Viewer.

    Science.gov (United States)

    Tkacz, Magdalena A; Chromiński, Kornel; Idziak-Helmcke, Dominika; Robaszkiewicz, Ewa; Hasterok, Robert

    2016-01-01

    This paper presents ChroTeMo, a tool for chromosome territory modelling, accompanied by ChroTeVi-a chromosome territory visualisation software that uses the data obtained by ChroTeMo. These tools have been developed in order to complement the molecular cytogenetic research of interphase nucleus structure in a model grass Brachypodium distachyon. Although the modelling tool has been initially created for one particular species, it has universal application. The proposed version of ChroTeMo allows for generating a model of chromosome territory distribution in any given plant or animal species after setting the initial, species-specific parameters. ChroTeMo has been developed as a fully probabilistic modeller. Due to this feature, the comparison between the experimental data on the structure of a nucleus and the results obtained from ChroTeMo can indicate whether the distribution of chromosomes inside a nucleus is also fully probabilistic or is subjected to certain non-random patterns. The presented tools have been written in Python, so they are multiplatform, portable and easy to read. Moreover, if necessary they can be further developed by users writing their portions of code. The source code, documentation, and wiki, as well as the issue tracker and the list of related articles that use ChroTeMo and ChroTeVi, are accessible in a public repository at Github under GPL 3.0 license.

  5. Thermal inactivation kinetics of partially purified mango pectin methylesterase

    Directory of Open Access Journals (Sweden)

    Claudio Alonso DÍAZ-CRUZ

    2016-01-01

    Full Text Available Abstract Kinetic parameters of thermal inactivation of pectin methylesterase (PME in a partially purified mango enzyme extract were determined. The PME of mango partially purified by salting out showed different patterns of thermal inactivation, indicating the presence of a thermostable fraction at 70 °C and a thermolabile fraction at lower temperatures. The inactivation of the thermostable fraction exhibited a linear behavior that yielded a z-value of 9.44 °C and an activation energy (Ea of 245.6 kJ mol-1 K-1 using the Arrhenius model. The thermostable mango PME fraction represented 17% of total crude enzyme extract, which emphasizes the importance of residual enzyme activity after heat treatment.

  6. Reconstruction of genomic rearrangements in great apes and gibbons by chromosome painting

    OpenAIRE

    Jauch, Anna; Wienberg, Johannes; Stanyon, Roscoe; Arnold, N; S. Tofanelli; ISHIDA, T.; Cremer, Thomas

    1992-01-01

    The homology between hylobatid chromosomes and other primates has long remained elusive. We used chromosomal in situ suppression hybridization of all human chromosome-specific DNA libraries to "paint" the chromosomes of primates and establish homologies between the human, great ape (chimpanzee, gorilla, and orangutan), and gibbon karyotypes (Hylobates lar species group, 2n = 44). The hybridization patterns unequivocally demonstrate the high degree of chromosomal homology and synteny of great ...

  7. The X factor: X chromosome dosage compensation in the evolutionarily divergent monotremes and marsupials.

    Science.gov (United States)

    Whitworth, Deanne J; Pask, Andrew J

    2016-08-01

    Marsupials and monotremes represent evolutionarily divergent lineages from the majority of extant mammals which are eutherian, or placental, mammals. Monotremes possess multiple X and Y chromosomes that appear to have arisen independently of eutherian and marsupial sex chromosomes. Dosage compensation of X-linked genes occurs in monotremes on a gene-by-gene basis, rather than through chromosome-wide silencing, as is the case in eutherians and marsupials. Specifically, studies in the platypus have shown that for any given X-linked gene, a specific proportion of nuclei within a cell population will silence one locus, with the percentage of cells undergoing inactivation at that locus being highly gene-specific. Hence, it is perhaps not surprising that the expression level of X-linked genes in female platypus is almost double that in males. This is in contrast to the situation in marsupials where one of the two X chromosomes is inactivated in females by the long non-coding RNA RSX, a functional analogue of the eutherian XIST. However, marsupial X chromosome inactivation differs from that seen in eutherians in that it is exclusively the paternal X chromosome that is silenced. In addition, marsupials appear to have globally upregulated X-linked gene expression in both sexes, thus balancing their expression levels with those of the autosomes, a process initially proposed by Ohno in 1967 as being a fundamental component of the X chromosome dosage compensation mechanism but which may not have evolved in eutherians.

  8. Chromosome territories, X;Y translocation and Premature Ovarian Failure: is there a relationship?

    Directory of Open Access Journals (Sweden)

    Betri Enrico

    2009-09-01

    Full Text Available Abstract Background Premature ovarian failure (POF is a secondary hypergonadotrophic amenorrhea occurring before the age of 40 and affecting 1-3% of females. Chromosome anomalies account for 6-8% of POF cases, but only few cases are associated with translocations involving X and Y chromosomes. This study shows the cytogenetic and molecular analysis of a POF patient came to our attention as she developed a left ovary choriocarcinoma at the age of 10 and at 14 years of age she presented secondary amenorrhea with elevated levels of gonadotropins. Results Breakpoint position on X and Y chromosomes was investigated using Fluorescent In Situ Hybridisation (FISH with a panel of specific BAC probes, microsatellite analysis and evaluation of copy number changes and loss of heterozigosity by Affymetrix® GeneChip platform (Santa Clara, CA, USA. Patient's karyotype resulted 46, X, der(Yt(X;Y(q13.1;q11.223. X inactivation study was assessed by RBA banding and showed preferential inactivation of derivative chromosome. The reciprocal spatial disposition of sexual chromosome territories was investigated using whole chromosome painting and centromeres probes: patient's results didn't show a significant difference in comparison to normal controls. Conclusion The peculiar clinical case come to our attention highlighted the complexity of POF aetiology and of the translocation event, even if our results seem to exclude any effect on nuclear organisation. POF phenotype could be partially explained by skewed X chromosome inactivation that influences gene expression.

  9. Resistance of bovine spongiform encephalopathy (BSE prions to inactivation.

    Directory of Open Access Journals (Sweden)

    Kurt Giles

    2008-11-01

    Full Text Available Distinct prion strains often exhibit different incubation periods and patterns of neuropathological lesions. Strain characteristics are generally retained upon intraspecies transmission, but may change on transmission to another species. We investigated the inactivation of two related prions strains: BSE prions from cattle and mouse-passaged BSE prions, termed 301V. Inactivation was manipulated by exposure to sodium dodecyl sulfate (SDS, variations in pH, and different temperatures. Infectivity was measured using transgenic mouse lines that are highly susceptible to either BSE or 301V prions. Bioassays demonstrated that BSE prions are up to 1,000-fold more resistant to inactivation than 301V prions while Western immunoblotting showed that short acidic SDS treatments reduced protease-resistant PrP(Sc from BSE prions and 301V prions at similar rates. Our findings argue that despite being derived from BSE prions, mouse 301V prions are not necessarily a reliable model for cattle BSE prions. Extending these comparisons to human sporadic Creutzfeldt-Jakob disease and hamster Sc237 prions, we found that BSE prions were 10- and 10(6-fold more resistant to inactivation, respectively. Our studies contend that any prion inactivation procedures must be validated by bioassay against the prion strain for which they are intended to be used.

  10. Resistance of bovine spongiform encephalopathy (BSE) prions to inactivation.

    Science.gov (United States)

    Giles, Kurt; Glidden, David V; Beckwith, Robyn; Seoanes, Rose; Peretz, David; DeArmond, Stephen J; Prusiner, Stanley B

    2008-11-01

    Distinct prion strains often exhibit different incubation periods and patterns of neuropathological lesions. Strain characteristics are generally retained upon intraspecies transmission, but may change on transmission to another species. We investigated the inactivation of two related prions strains: BSE prions from cattle and mouse-passaged BSE prions, termed 301V. Inactivation was manipulated by exposure to sodium dodecyl sulfate (SDS), variations in pH, and different temperatures. Infectivity was measured using transgenic mouse lines that are highly susceptible to either BSE or 301V prions. Bioassays demonstrated that BSE prions are up to 1,000-fold more resistant to inactivation than 301V prions while Western immunoblotting showed that short acidic SDS treatments reduced protease-resistant PrP(Sc) from BSE prions and 301V prions at similar rates. Our findings argue that despite being derived from BSE prions, mouse 301V prions are not necessarily a reliable model for cattle BSE prions. Extending these comparisons to human sporadic Creutzfeldt-Jakob disease and hamster Sc237 prions, we found that BSE prions were 10- and 10(6)-fold more resistant to inactivation, respectively. Our studies contend that any prion inactivation procedures must be validated by bioassay against the prion strain for which they are intended to be used.

  11. Advanced microtechnologies for detection of chromosome abnormalities by fluorescent in situ hybridization

    DEFF Research Database (Denmark)

    Kwasny, Dorota; Vedarethinam, Indumathi; Shah, Pranjul

    2012-01-01

    Cytogenetic and molecular cytogenetic analyses, which aim to detect chromosome abnormalities, are routinely performed in cytogenetic laboratories all over the world. Traditional cytogenetic studies are performed by analyzing the banding pattern of chromosomes, and are complemented by molecular cy...

  12. Major factors influencing linkage disequilibrium by analysis of different chromosome regions in distinct populations: demography, chromosome recombination frequency and selection.

    Science.gov (United States)

    Zavattari, P; Deidda, E; Whalen, M; Lampis, R; Mulargia, A; Loddo, M; Eaves, I; Mastio, G; Todd, J A; Cucca, F

    2000-12-12

    Linkage disequilibrium (LD) mapping of disease genes is complicated by population- and chromosome-region-specific factors. We have analysed demographic factors by contrasting intermarker LD results obtained in a large cosmopolitan population (UK), a large genetic isolate (Sardinia) and a subisolate (village of Gavoi) for two regions of the X chromosome. A dramatic increase of LD was found in the subisolate. Demographic history of populations therefore influences LD. Chromosome-region-specific effects, namely the pattern and frequency of homologous recombination, were next delineated by the analysis of chromosome 6p21, including the HLA region. Patterns of global LD in this region were very similar in the UK and Sardinian populations despite their entirely distinct demographies, and correlate well with the pattern of recombinations. Nevertheless, haplotypes extend across recombination hot spots indicative of selection of certain haplotypes. Subisolate aside, chromosome-region-specific differences in LD patterns appear to be more important than the differences in intermarker LD between distinct populations.

  13. Nonuniform processes of chromosome evolution in sedges (Carex: Cyperaceae).

    Science.gov (United States)

    Hipp, Andrew L

    2007-09-01

    Holocentric chromosomes-chromosomes that lack localized centromeres-occur in numerous unrelated clades of insects, flatworms, and angiosperms. Chromosome number changes in such organisms often result from fission and fusion events rather than polyploidy. In this study, I test the hypothesis that chromosome number evolves according to a uniform process in Carex section Ovales (Cyperaceae), the largest New World section of an angiosperm genus renowned for its chromosomal variability and species richness. I evaluate alternative models of chromosome evolution that allow for shifts in both stochastic and deterministic evolutionary processes and that quantify the rate of evolution and heritability/phylogenetic dependence of chromosome number. Estimates of Ornstein-Uhlenbeck model parameters and tree-scaling parameters in a generalized least squares framework demonstrate that (1) chromosome numbers evolve rapidly toward clade-specific stationary distributions that cannot be explained by constant variance (Brownian motion) evolutionary models, (2) chromosome evolution in the section is rapid and exhibits little phylogenetic inertia, and (3) explaining the phylogenetic pattern of chromosome numbers in the section entails inferring a shift in evolutionary dynamics at the root of a derived clade. The finding that chromosome evolution is not a uniform process in sedges provides a novel example of karyotypic orthoselection in an organism with holocentric chromosomes.

  14. Computerized prototypes of DAPI-stained chromosomes for FISH analysis

    Energy Technology Data Exchange (ETDEWEB)

    Baldini, A.; Smith, L.C.; Knapp, R.D. [Baylor College of Medicine, Houston, TX (United States)

    1994-09-01

    DAPI is fluorescent dye widely used in chromosome counterstaining for fluorescence in situ hybridization (FISH) experiments. It produces a Q-banding pattern that allows chromosomes to be identified and permits molecular probes to be assigned to specific cytogenetic bands. Using a statistical procedure based on eigenanalysis, we have extracted features from digital images of DAPI-stained chromosomes and constructed prototypes of each of the 24 human chromosomes. The features of prototypes are directly proportional, in intensity profile and band location, to those of real chromosomes. The prototype`s intensity profile can be translated into cytogenetic bands to provide a computer-based strategy for chromosome mapping and analysis amenable to automation. Data have been obtained using images from the 24 human chromosomes and mouse X chromosome. Moreover, the same procedure is general and can be used for the analysis of chromosomes from other species, as well as with banding techniques other than those using DAPI. Images of hybridization patterns produced by complex probes are also suitable for this analysis. The speed and flexibility of the procedure opens the way to application so far unexplored, such as computer-assisted chromosome band assignment of probe; combined analysis of multiple, geometrically distorted chromosomes; and the direct comparison of raw data from different experiments. The applications will not be limited to mapping experiments but will include analysis of chromosome structure, variability and analysis of the pattern of chromosome distribution of repetitive sequences. The results from such analysis is suitable for objective statistical evaluation and, eventually, for autonomous machine interpretation.

  15. Chromosome Imbalance as a Driver of Sex Disparity in Disease

    OpenAIRE

    2014-01-01

    It has long been recognized that men and women exhibit different risks for diverse disorders ranging from metabolic to autoimmune diseases. However, the underlying causes of these disparities remain obscure. Analysis of patients with chromosomal abnormalities, including Turner syndrome (45X) and Klinefelter syndrome (47XXY), has highlighted the importance of X-linked gene dosage as a contributing factor for disease susceptibility. Escape from X-inactivation and X-linked imprinting can result ...

  16. Analysis of plant meiotic chromosomes by chromosome painting.

    Science.gov (United States)

    Lysak, Martin A; Mandáková, Terezie

    2013-01-01

    Chromosome painting (CP) refers to visualization of large chromosome regions, entire chromosome arms, or entire chromosomes via fluorescence in situ hybridization (FISH). For CP in plants, contigs of chromosome-specific bacterial artificial chromosomes (BAC) from the target species or from a closely related species (comparative chromosome painting, CCP) are typically applied as painting probes. Extended pachytene chromosomes provide the highest resolution of CP in plants. CP enables identification and tracing of particular chromosome regions and/or entire chromosomes throughout all meiotic stages as well as corresponding chromosome territories in premeiotic interphase nuclei. Meiotic pairing and structural chromosome rearrangements (typically inversions and translocations) can be identified by CP. Here, we describe step-by-step protocols of CP and CCP in plant species including chromosome preparation, BAC DNA labeling, and multicolor FISH.

  17. Soybean chromosome painting: a strategy for somatic cytogenetics.

    Science.gov (United States)

    Shi, L; Zhu, T; Morgante, M; Rafalski, J A; Keim, P

    1996-01-01

    Cytological identification of soybean mitotic metaphase chromosomes (2n = 40) has been severely limited by their small size and uniform karyomorphology. We have developed fluorescent in situ hybridization (FISH), PCR-primed in situ labelling (PCR-PRINS) procedures, and molecular probes for routine cytological identification and for the physical mapping of soybean somatic chromosomes. Chromosome preparation has been achieved by modifications of previous protocols and through the preparation of root-tip protoplasts prior to chromosome spreading. Initially our probe selection focused on highly repeated DNAs that provide very intense localized hybridization signals. Repetitive gene probes that have proven valuable include the rDNA loci (5S and 45S) which are chromosome specific. We have also developed satellite DNA probes for two different sequence families: the SB92 and the STR120 satellites. Both of these are tandemly arranged at multiple chromosomal loci. By using different cloned examples of each family, we have been able to selectively label unique subsets of soybean chromosomes. Double hybridization with biotin and digoxigenin labeled probes has allowed us to determine the chromosomal overlap between different probes. In addition, we have joined portions of the metaphase chromosome painting patterns with the genetic map by single-copy FISH and PCR-PRINS detection of the RFLP loci G8.15, G17.3, and A199a and A199b. Total genomic DNA in situ hybridization (GISH) patterns were also used to characterize the soybean chromosomes.

  18. A conserved checkpoint monitors meiotic chromosome synapsis inCaenorhabditis elegans

    Energy Technology Data Exchange (ETDEWEB)

    Bhalla, Needhi; Dernburg, Abby F.

    2005-07-14

    We report the discovery of a checkpoint that monitorssynapsis between homologous chromosomes to ensure accurate meioticsegregation. Oocytes containing unsynapsed chromosomes selectivelyundergo apoptosis even if agermline DNA damage checkpoint is inactivated.This culling mechanism isspecifically activated by unsynapsed pairingcenters, cis-acting chromosomesites that are also required to promotesynapsis in Caenorhabditis elegans. Apoptosis due to synaptic failurealso requires the C. elegans homolog of PCH2,a budding yeast pachytenecheckpoint gene, which suggests that this surveillance mechanism iswidely conserved.

  19. The Precarious Prokaryotic Chromosome

    OpenAIRE

    Kuzminov, Andrei

    2014-01-01

    Evolutionary selection for optimal genome preservation, replication, and expression should yield similar chromosome organizations in any type of cells. And yet, the chromosome organization is surprisingly different between eukaryotes and prokaryotes. The nuclear versus cytoplasmic accommodation of genetic material accounts for the distinct eukaryotic and prokaryotic modes of genome evolution, but it falls short of explaining the differences in the chromosome organization. I propose that the t...

  20. Mechanisms for chromosome segregation.

    Science.gov (United States)

    Bouet, Jean-Yves; Stouf, Mathieu; Lebailly, Elise; Cornet, François

    2014-12-01

    Bacteria face the problem of segregating their gigantic chromosomes without a segregation period restricted in time and space, as Eukaryotes do. Segregation thus involves multiple activities, general or specific of a chromosome region and differentially controlled. Recent advances show that these various mechanisms conform to a “pair and release” rule, which appears as a general rule in DNA segregation. We describe the latest advances in segregation of bacterial chromosomes with emphasis on the different pair and release mechanisms.

  1. Epigenetics and autoimmune diseases: the X chromosome-nucleolus nexus.

    Science.gov (United States)

    Brooks, Wesley H; Renaudineau, Yves

    2015-01-01

    Autoimmune diseases occur more often in females, suggesting a key role for the X chromosome. X chromosome inactivation, a major epigenetic feature in female cells that provides dosage compensation of X-linked genes to avoid overexpression, presents special vulnerabilities that can contribute to the disease process. Disruption of X inactivation can result in loss of dosage compensation with expression from previously sequestered genes, imbalance of gene products, and altered endogenous material out of normal epigenetic context. In addition, the human X has significant differences compared to other species and these differences can contribute to the frequency and intensity of the autoimmune disease in humans as well as the types of autoantigens encountered. Here a link is demonstrated between autoimmune diseases, such as systemic lupus erythematosus, and the X chromosome by discussing cases in which typically non-autoimmune disorders complicated with X chromosome abnormalities also present lupus-like symptoms. The discussion is then extended to the reported spatial and temporal associations of the inactive X chromosome with the nucleolus. When frequent episodes of cellular stress occur, the inactive X chromosome may be disrupted and inadvertently become involved in the nucleolar stress response. Development of autoantigens, many of which are at least transiently components of the nucleolus, is then described. Polyamines, which aid in nucleoprotein complex assembly in the nucleolus, increase further during cell stress, and appear to have an important role in the autoimmune disease process. Autoantigenic endogenous material can potentially be stabilized by polyamines. This presents a new paradigm for autoimmune diseases: that many are antigen-driven and the autoantigens originate from altered endogenous material due to episodes of cellular stress that disrupt epigenetic control. This suggests that epigenetics and the X chromosome are important aspects of autoimmune

  2. Double-strand break repair on sex chromosomes: challenges during male meiotic prophase.

    Science.gov (United States)

    Lu, Lin-Yu; Yu, Xiaochun

    2015-01-01

    During meiotic prophase, DNA double-strand break (DSB) repair-mediated homologous recombination (HR) occurs for exchange of genetic information between homologous chromosomes. Unlike autosomes or female sex chromosomes, human male sex chromosomes X and Y share little homology. Although DSBs are generated throughout male sex chromosomes, homologous recombination does not occur for most regions and DSB repair process is significantly prolonged. As a result, male sex chromosomes are coated with many DNA damage response proteins and form a unique chromatin structure known as the XY body. Interestingly, associated with the prolonged DSB repair, transcription is repressed in the XY body but not in autosomes, a phenomenon known as meiotic sex chromosome inactivation (MSCI), which is critical for male meiosis. Here using mice as model organisms, we briefly summarize recent progress on DSB repair in meiotic prophase and focus on the mechanism and function of DNA damage response in the XY body.

  3. Bacterial chromosome segregation.

    Science.gov (United States)

    Possoz, Christophe; Junier, Ivan; Espeli, Olivier

    2012-01-01

    Dividing cells have mechanisms to ensure that their genomes are faithfully segregated into daughter cells. In bacteria, the description of these mechanisms has been considerably improved in the recent years. This review focuses on the different aspects of bacterial chromosome segregation that can be understood thanks to the studies performed with model organisms: Escherichia coli, Bacillus subtilis, Caulobacter crescentus and Vibrio cholerae. We describe the global positionning of the nucleoid in the cell and the specific localization and dynamics of different chromosomal loci, kinetic and biophysic aspects of chromosome segregation are presented. Finally, a presentation of the key proteins involved in the chromosome segregation is made.

  4. Chromosome oscillations in mitosis

    Science.gov (United States)

    Campas, Otger

    2008-03-01

    Successful cell division necessitates a tight regulation of chromosome movement via the activity of molecular motors. Many of the key players at the origin of the forces generating the motion have been identified, but their spatial and temporal organization remains elusive. In animal cells, chromosomes periodically switch between phases of movement towards and away from the pole. This characteristic oscillatory behaviour cannot be explained by the current models of chromosome positioning and congression. We perform a self-contained theoretical analysis in which the motion of mono-oriented chromosomes results from the competition between the activity of the kinetochore and chromokinesin motors on the chromosome arms. Our analysis, consistent with the available experimental data, proposes that the interplay between the aster-like morphology of the spindle and the collective kinetics of molecular motors is at the origin of chromosome oscillations, positioning and congression. It provides a natural explanation for the so-called chromosome directional instability and for the mechanism by which chromosomes sense their position in space. In addition, we estimate the in vivo velocity of chromokinesins at vanishing load and propose new experiments to assess the mechanism at the origin of chromosome movement in cell division.

  5. Chromosome banding and gene localizations support extensive conservation of chromosome structure between cattle and sheep.

    Science.gov (United States)

    Hediger, R; Ansari, H A; Stranzinger, G F

    1991-01-01

    By using three gene probes, one derived from the porcine major histocompatibility complex (MHC) and two from bovine cytokeratin genes, type I (KRTA) and type II (KRTB), the hypothesis of conservation of genome structure in two members of the family Bovidae was examined. Gene mapping data revealed the MHC to be in chromosome region 23q15----q23 in cattle (BOLA) and 20q15----q23 in sheep (OLA). KRTA was localized to chromosome region 19q25----q29 in cattle and 11q25----q29 in sheep and KRTB to 5q14----q22 in cattle and 3q14----q22 in sheep. The banding patterns of the chromosome arms to which the loci were assigned were identical in both species. Moreover, the resemblances of GTG- or QFQ-banding patterns between the cattle and sheep karyotypes illustrated further chromosome homologies. These studies, based on gene mapping comparisons and comparative cytogenetics, document that within bovid chromosomes, homology of banding patterns corresponds to a homologous genetic structure. Hence, we propose that gene assignments on identified chromosomal segments in one species of the Bovidae can be extrapolated, in general, to other bovid species based on the banding homologies presented here.

  6. Fetal chromosome analysis: screening for chromosome disease?

    DEFF Research Database (Denmark)

    Philip, J; Tabor, Ann; Bang, J

    1983-01-01

    The aim of the study was to investigate the rationale of the current indications for fetal chromosome analysis. 5372 women had 5423 amniocentesis performed, this group constituting a consecutive sample at the chromosome laboratory, Rigshospitalet, Copenhagen from March 1973 to September 1980 (Group...... to women having amniocentesis, although considered not to have any increased risk of fetal chromosome abnormality (1390 pregnancies, group B). They were also compared with 750 consecutive pregnancies in women 25-34 years of age, in whom all heritable diseases were excluded (group C). The risk of unbalanced...... with women without elevated risk. Spontaneous abortion rate and prematurity rate did not differ from rates expected without amniocentesis. It is concluded that current indications may be characterized as a mixture of evident high risk factors and factors with only a minor influence on risk. Indications...

  7. X chromosome inactivation patterns in patients with Rett syndrome and their mothers and the parental origin of the priority inactive X chromosome%Rett综合征X染色体失活方式及失活X染色体起源研究

    Institute of Scientific and Technical Information of China (English)

    姜胜玲; 包新华; 宋福英; 潘虹; 李美蓉; 吴希如

    2006-01-01

    目的 研究Rett综合征(RTT)患儿和其母亲X染色体失活(XCI)方式,患儿失活X染色体来源,探讨RTT XCI与基因型、表型和遗传方式之间的关系.方法 对55例RTT患儿、53例RTT患儿的母亲、48例正常女性对照,提取其周围血白细胞DNA,经甲基化敏感性限制性核酸内切酶HpaⅡ消化,对消化前后雄激素受体(AR)基因片段行PCR扩增和基因扫描分析.结果 RTT患儿、RTT患儿母亲、正常对照AR基因片段杂合率分别为82%、77%、83%.RTT患儿XCI分布方式与患儿母亲及对照组相比,差异有统计学意义(P<0.05),RTT患儿母亲与正常对照组相比,差异无统计学意义(P>0.05).与患儿母亲及对照组相比,RTT患儿在50∶50~59∶41区段内患儿人数显著减少,差异有统计学意义(P<0.05).RTT患儿非随机失活在XCI≥65∶35和≥80∶20范围与母亲及对照组相比人数增多,但差异无统计学意义(P>0.05).在21例非随机失活的患儿中,18例倾向于父源X染色体失活,占85.7%,3例倾向于母源.在同一突变位点可以观察到各种XCI方式,T158M高度非随机失活率略高,R133C无高度非随机失活.非典型RTT比典型RTT高度非随机失活率增高,其中保留语言型与先天型相比,高度非随机失活率略高.结论 RTT患儿XCI分布方式与及母亲及对照组相比,完全随机失活人数显著减少,但在非随机失活人数上差异无统计学意义.母亲作为携带者传递致病基因不是RTT主要的遗传方式.RTT患儿非随机失活的X染色体主要起源于父亲.RTT患儿的XCI方式与临床表型有一定相关性,但XCI并不能完全解释表型.

  8. XYY chromosome anomaly and schizophrenia.

    Science.gov (United States)

    Rajagopalan, M; MacBeth, R; Varma, S L

    1998-02-07

    Sex chromosome anomalies have been associated with psychoses, and most of the evidence is linked to the presence of an additional X chromosome. We report a patient with XYY chromosome anomaly who developed schizophrenia.

  9. Deficit of mitonuclear genes on the human X chromosome predates sex chromosome formation.

    Science.gov (United States)

    Dean, Rebecca; Zimmer, Fabian; Mank, Judith E

    2015-01-29

    Two taxa studied to date, the therian mammals and Caenorhabditis elegans, display underrepresentations of mitonuclear genes (mt-N genes, nuclear genes whose products are imported to and act within the mitochondria) on their X chromosomes. This pattern has been interpreted as the result of sexual conflict driving mt-N genes off of the X chromosome. However, studies in several other species have failed to detect a convergent biased distribution of sex-linked mt-N genes, leading to questions over the generality of the role of sexual conflict in shaping the distribution of mt-N genes. Here we tested whether mt-N genes moved off of the therian X chromosome following sex chromosome formation, consistent with the role of sexual conflict, or whether the paucity of mt-N genes on the therian X is a chance result of an underrepresentation on the ancestral regions that formed the X chromosome. We used a synteny-based approach to identify the ancestral regions in the platypus and chicken genomes that later formed the therian X chromosome. We then quantified the movement of mt-N genes on and off of the X chromosome and the distribution of mt-N genes on the human X and ancestral X regions. We failed to find an excess of mt-N gene movement off of the X. The bias of mt-N genes on ancestral therian X chromosomes was also not significantly different from the biases on the human X. Together our results suggest that, rather than conflict driving mt-N genes off of the mammalian X, random biases on chromosomes that formed the X chromosome could explain the paucity of mt-N genes in the therian lineage.

  10. Hydrazine vapor inactivates Bacillus spores

    Science.gov (United States)

    Schubert, Wayne W.; Engler, Diane L.; Beaudet, Robert A.

    2016-05-01

    NASA policy restricts the total number of bacterial spores that can remain on a spacecraft traveling to any planetary body which might harbor life or have evidence of past life. Hydrazine, N2H4, is commonly used as a propellant on spacecraft. Hydrazine as a liquid is known to inactivate bacterial spores. We have now verified that hydrazine vapor also inactivates bacterial spores. After Bacillus atrophaeus ATCC 9372 spores deposited on stainless steel coupons were exposed to saturated hydrazine vapor in closed containers, the spores were recovered from the coupons, serially diluted, pour plated and the surviving bacterial colonies were counted. The exposure times required to reduce the spore population by a factor of ten, known as the D-value, were 4.70 ± 0.50 h at 25 °C and 2.85 ± 0.13 h at 35 °C. These inactivation rates are short enough to ensure that the bioburden of the surfaces and volumes would be negligible after prolonged exposure to hydrazine vapor. Thus, all the propellant tubing and internal tank surfaces exposed to hydrazine vapor do not contribute to the total spore count.

  11. Behavior modification after inactivation of cerebellar dentate nuclei.

    Science.gov (United States)

    Peterson, Todd C; Villatoro, Lee; Arneson, Tom; Ahuja, Brittany; Voss, Stephanie; Swain, Rodney A

    2012-08-01

    Effort-based decision making occurs when subjects are given a choice between a reward available at a high response cost and a reward available at a low response cost and is altered in individuals with disorders such as autism or particular patterns of brain injury. The current study explored the relationship between effort-based decision making and reinforcement characteristics in the T maze. This was done using both normal animals and animals with bilateral inactivation of the cerebellar dentate nuclei. Rats chose between alternatives in which one arm contained high-density reinforcement (HR) and the other arm contained low-density reinforcement (LR). During training, the HR arm was obstructed and the point at which the animal no longer worked for reinforcement (breaking point) was determined. The cerebellar dentate nuclei were then transiently inactivated and once again breaking points were assessed. The results indicated that inactivation of the dentate nucleus disrupted effort-based decision making. Additionally, altering both the palatability and the magnitude of the reinforcement were assessed in an attempt to reestablish the original preinactivation breaking point. It was hypothesized that an increase in the strength or magnitude of the reinforcement would promote an increase in the breaking point of the animal even when the cerebellum was inactivated. The results indicated that with both strategies animals effectively reestablished original breaking points. The results of this study will inform the current literature regarding the modification of behavior after brain injury and further the understanding of the behavioral deficits associated with cerebellar dysfunction.

  12. Y chromosome microdeletions in azoospermic patients with Klinefelter's syndrome

    Institute of Scientific and Technical Information of China (English)

    Anurag Mitra; Rima Dada; Rajeev Kumar; Narmada Prasad Gupta; Kiran Kucheria; Satish Kumar Gupta

    2006-01-01

    Aim: To study the occurrence of Y chromosome microdeletions in azoospermic patients with Klinefelter's syndrome (KFS). Methods: Blood and semen samples were collected from azoospermic patients with KFS (n = 14) and a control group of men of proven fertility (n = 13). Semen analysis was done according to World Health Organization (WHO) guidelines. Blood samples were processed for karyotyping, fluorescent in situ hybridization (FISH) and measurement of plasma follicle stimulating hormone (FSH) by radioimmunoassay. To determine Y chromosome microdeletions, polymerase chain reaction (PCR) of 16 sequence tagged sites (STS) and three genes (DFFRY, XKRY and RBM1 Y) was performed on isolated genomic DNA. Testicular fine needle aspiration cytology (FNAC) was done in selected cases. Results: Y chromosome microdeletions spanning the azoospermia factor (AZF)a and AZFb loci were found in four of the 14 azoospermic patients with KFS. Karyotype and FISH analysis revealed that, of the four cases showing Y chromosome microdeletion, three cases had a 47,XXY/46,XY chromosomal pattern and one case had a 46,XY/47,XXY/48,XXXY/48,XXYY chromosomal pattern. The testicular FNAC of one sample with Y chromosome microdeletion revealed Sertoli cell-only type of morphology. However, no Y chromosome microdeletions were observed in any of the 13 fertile men. All patients with KFS had elevated plasma FSH levels. Conclusion:Patients with KFS may harbor Y chromosome microdeletions and screening for these should be a part of their diagnostic work-up, particularly in those considering assisted reproductive techniques.

  13. Meiotic silencing and fragmentation of the male germline restricted chromosome in zebra finch

    NARCIS (Netherlands)

    S. Schoenmakers (Sam); E. Wassenaar (Evelyne); J.S.E. Laven (Joop); J.A. Grootegoed (Anton); W.M. Baarends (Willy)

    2010-01-01

    textabstractDuring male meiotic prophase in mammals, X and Y are in a largely unsynapsed configuration, which is thought to trigger meiotic sex chromosome inactivation (MSCI). In avian species, females are ZW, and males ZZ. Although Z and W in chicken oocytes show complete, largely heterologous syna

  14. Meiotic behaviour of individual chromosomes in allotriploid Alstroemeria hybrids.

    Science.gov (United States)

    Kamstra, S A; de Jong, J H; Jacobsen, E; Ramanna, M S; Kuipers, A G J

    2004-07-01

    Chromosome association and chiasma formation were studied in pollen mother cells at metaphase I of four allotriplod BC1 plants (2n=3x=24) obtained from the backcross of the hybrid Alstroemeria aurea x A. inodora with its parent A. inodora. We distinguished the chromosomes of both parental species by genomic in situ hybridization (GISH), whereas the individual chromosomes were identified on the basis of their multicolour FISH banding patterns obtained after a second hybridization with two species-specific satellite repeats as probes. All the four BC1 plants possessed two genomes of A. inodora and one of A. aurea. Variable numbers of recombinant chromosomes, resulting from meiotic recombination in the interspecific hybrid, were present in these plants. The homologous A. inodora chromosomes generally formed bivalents, leaving the homoeologous A. aurea chromosomes unassociated. High frequencies of trivalents were observed for the chromosome sets that contained recombinant chromosomes, even when the recombinant segments were small. Chromosome associations in the trivalents were restricted to homologous segments. The implications of the absence of homoeologous chromosome pairing on gamete constitution and prospects for introgression in Alstroemeria are discussed.

  15. Sequential cloning of chromosomes

    Science.gov (United States)

    Lacks, S.A.

    1995-07-18

    A method for sequential cloning of chromosomal DNA of a target organism is disclosed. A first DNA segment homologous to the chromosomal DNA to be sequentially cloned is isolated. The first segment has a first restriction enzyme site on either side. A first vector product is formed by ligating the homologous segment into a suitably designed vector. The first vector product is circularly integrated into the target organism`s chromosomal DNA. The resulting integrated chromosomal DNA segment includes the homologous DNA segment at either end of the integrated vector segment. The integrated chromosomal DNA is cleaved with a second restriction enzyme and ligated to form a vector-containing plasmid, which is replicated in a host organism. The replicated plasmid is then cleaved with the first restriction enzyme. Next, a DNA segment containing the vector and a segment of DNA homologous to a distal portion of the previously isolated DNA segment is isolated. This segment is then ligated to form a plasmid which is replicated within a suitable host. This plasmid is then circularly integrated into the target chromosomal DNA. The chromosomal DNA containing the circularly integrated vector is treated with a third, retrorestriction (class IIS) enzyme. The cleaved DNA is ligated to give a plasmid that is used to transform a host permissive for replication of its vector. The sequential cloning process continues by repeated cycles of circular integration and excision. The excision is carried out alternately with the second and third enzymes. 9 figs.

  16. Chromosomal mosaicism goes global

    Directory of Open Access Journals (Sweden)

    Yurov Yuri B

    2008-11-01

    Full Text Available Intercellular differences of chromosomal content in the same individual are defined as chromosomal mosaicism (alias intercellular or somatic genomic variations or, in a number of publications, mosaic aneuploidy. It has long been suggested that this phenomenon poorly contributes both to intercellular (interindividual diversity and to human disease. However, our views have recently become to change due to a series of communications demonstrated a higher incidence of chromosomal mosaicism in diseased individuals (major psychiatric disorders and autoimmune diseases as well as depicted chromosomal mosaicism contribution to genetic diversity, the central nervous system development, and aging. The later has been produced by significant achievements in the field of molecular cytogenetics. Recently, Molecular Cytogenetics has published an article by Maj Hulten and colleagues that has provided evidences for chromosomal mosaicism to underlie formation of germline aneuploidy in human female gametes using trisomy 21 (Down syndrome as a model. Since meiotic aneuploidy is suggested to be the leading genetic cause of human prenatal mortality and postnatal morbidity, these data together with previous findings define chromosomal mosaicism not as a casual finding during cytogenetic analyses but as a more significant biological phenomenon than previously recognized. Finally, the significance of chromosomal mosaicism can be drawn from the fact, that this phenomenon is involved in genetic diversity, normal and abnormal prenatal development, human diseases, aging, and meiotic aneuploidy, the intrinsic cause of which remains, as yet, unknown.

  17. CHROMOSOMES OF AMERICAN MARSUPIALS.

    Science.gov (United States)

    BIGGERS, J D; FRITZ, H I; HARE, W C; MCFEELY, R A

    1965-06-18

    Studies of the chromosomes of four American marsupials demonstrated that Caluromys derbianus and Marmosa mexicana have a diploid number of 14 chromosomes, and that Philander opossum and Didelphis marsupialis have a diploid number of 22. The karyotypes of C. derbianus and M. mexicana are similar, whereas those of P. opossum and D. marsupialis are dissimilar. If the 14-chromosome karyotype represents a reduction from a primitive number of 22, these observations suggest that the change has occurred independently in the American and Australasian forms.

  18. Phosphorylation of CDK2 on threonine 160 influences silencing of sex chromosome during male meiosis.

    Science.gov (United States)

    Wang, Lu; Liu, Wenjing; Zhao, Weidong; Song, Gendi; Wang, Guishuan; Wang, Xiaorong; Sun, Fei

    2014-06-01

    In mammalian meiosis, the X and Y chromosomes are largely unsynapsed and transcriptionally silenced during the pachytene stage of meiotic prophase (meiotic sex chromosome inactivation), forming a specialized nuclear territory called sex or XY body. An increasing number of proteins and noncoding RNAs were found to localize to the sex body and take part in influencing expression of sex chromosome genes. Cyclin-dependent kinase 2 (Cdk2 (-/-)) spermatocytes show incomplete sex chromosome pairing. Here, we further showed that phosphorylation of CDK2 isoform 1 (p-CDK2(39) [39 kDa]) on threonine 160 localizes to the sites of asynapsis and the sex body, interacting with phosphorylated gamma-H2AX. Meanwhile, p-CDK2(39) is frequently mislocalized throughout the sex body, and meiotic sex chromosome inactivation is disrupted in PWK×C57BL/6J hybrid mice. Furthermore, pachytene spermatocytes treated with mevastatin (an inhibitor of p-CDK2) showed overexpression of sex chromosome-linked genes. Our results highlight an important role for p-CDK2(39) in influencing silencing of the sex chromosomes during male meiosis by interacting with gamma-H2AX.

  19. The contribution of female meiotic drive to the evolution of neo-sex chromosomes.

    Science.gov (United States)

    Yoshida, Kohta; Kitano, Jun

    2012-10-01

    Sex chromosomes undergo rapid turnover in certain taxonomic groups. One of the mechanisms of sex chromosome turnover involves fusions between sex chromosomes and autosomes. Sexual antagonism, heterozygote advantage, and genetic drift have been proposed as the drivers for the fixation of this evolutionary event. However, all empirical patterns of the prevalence of multiple sex chromosome systems across different taxa cannot be simply explained by these three mechanisms. In this study, we propose that female meiotic drive may contribute to the evolution of neo-sex chromosomes. The results of this study showed that in mammals, the XY(1) Y(2) sex chromosome system is more prevalent in species with karyotypes of more biarmed chromosomes, whereas the X(1) X(2) Y sex chromosome system is more prevalent in species with predominantly acrocentric chromosomes. In species where biarmed chromosomes are favored by female meiotic drive, X-autosome fusions (XY(1) Y(2) sex chromosome system) will be also favored by female meiotic drive. In contrast, in species with more acrocentric chromosomes, Y-autosome fusions (X(1) X(2) Y sex chromosome system) will be favored just because of the biased mutation rate toward chromosomal fusions. Further consideration should be given to female meiotic drive as a mechanism in the fixation of neo-sex chromosomes.

  20. Combined fluorescent-chromogenic in situ hybridization for identification and laser microdissection of interphase chromosomes.

    Directory of Open Access Journals (Sweden)

    Nerea Paz

    Full Text Available Chromosome territories constitute the most conspicuous feature of nuclear architecture, and they exhibit non-random distribution patterns in the interphase nucleus. We observed that in cell nuclei from humans with Down Syndrome two chromosomes 21 frequently localize proximal to one another and distant from the third chromosome. To systematically investigate whether the proximally positioned chromosomes were always the same in all cells, we developed an approach consisting of sequential FISH and CISH combined with laser-microdissection of chromosomes from the interphase nucleus and followed by subsequent chromosome identification by microsatellite allele genotyping. This approach identified proximally positioned chromosomes from cultured cells, and the analysis showed that the identity of the chromosomes proximally positioned varies. However, the data suggest that there may be a tendency of the same chromosomes to be positioned close to each other in the interphase nucleus of trisomic cells. The protocol described here represents a powerful new method for genome analysis.

  1. Combined Fluorescent-Chromogenic In Situ Hybridization for Identification and Laser Microdissection of Interphase Chromosomes

    OpenAIRE

    Nerea Paz; Amaia Zabala; Félix Royo; África García-Orad; Zugaza, José L.; Parada, Luis A.

    2013-01-01

    Chromosome territories constitute the most conspicuous feature of nuclear architecture, and they exhibit non-random distribution patterns in the interphase nucleus. We observed that in cell nuclei from humans with Down Syndrome two chromosomes 21 frequently localize proximal to one another and distant from the third chromosome. To systematically investigate whether the proximally positioned chromosomes were always the same in all cells, we developed an approach consisting ...

  2. Chromosome complement, C-banding, Ag-NOR and replication banding in the zebrafish Danio rerio.

    Science.gov (United States)

    Daga, R R; Thode, G; Amores, A

    1996-01-01

    The chromosome complement of Danio rerio was investigated by Giemsa staining and C-banding, Ag-NORs and replication banding. The diploid number of this species is 2n = 50 and the arm number (NF) = 100. Constitutive heterochromatin was located at the centromeric position of all chromosome pairs. Nucleolus organizer regions appeared in the terminal position of the long arms of chromosomes 1, 2 and 8. Replication banding pattern allowed the identification of each chromosome pair.

  3. Prophage induction and inactivation by uv light. [Haemophilus influenzae

    Energy Technology Data Exchange (ETDEWEB)

    Barnhart, B.J.; Cox, S.H.; Jett, J.H.

    1976-06-01

    Analysis of the induction curves for uv light-irradiated Haemophilus influenzae lysogens and the distribution of pyrimidine dimers in a repair-deficient lysogen suggests that one dimer per prophage-size segment of the host bacterial chromosome is necessary as a preinduction event. The close correlations obtained prompted a renewed consideration of the possibility that direct prophage induction occurs when one dimer is stabilized within the prophage genome. The host excision-repair system apparently functions to reduce the probability of stabilizing within the prophage those dimers that are necessary for induction and inactivation. The presence of the inducible defective prophage in strain Rd depresses the inducibility of prophage HP1c1.

  4. Chromosomal abnormalities and autism

    Directory of Open Access Journals (Sweden)

    Farida El-Baz

    2016-01-01

    Conclusion: Chromosomal abnormalities were not detected in the studied autistic children, and so the relation between the genetics and autism still needs further work up with different study methods and techniques.

  5. Chromosome doubling method

    Science.gov (United States)

    Kato, Akio

    2006-11-14

    The invention provides methods for chromosome doubling in plants. The technique overcomes the low yields of doubled progeny associated with the use of prior techniques for doubling chromosomes in plants such as grasses. The technique can be used in large scale applications and has been demonstrated to be highly effective in maize. Following treatment in accordance with the invention, plants remain amenable to self fertilization, thereby allowing the efficient isolation of doubled progeny plants.

  6. Dynamics of Escherichia coli chromosome segregation during multifork replication.

    Science.gov (United States)

    Nielsen, Henrik J; Youngren, Brenda; Hansen, Flemming G; Austin, Stuart

    2007-12-01

    Slowly growing Escherichia coli cells have a simple cell cycle, with replication and progressive segregation of the chromosome completed before cell division. In rapidly growing cells, initiation of replication occurs before the previous replication rounds are complete. At cell division, the chromosomes contain multiple replication forks and must be segregated while this complex pattern of replication is still ongoing. Here, we show that replication and segregation continue in step, starting at the origin and progressing to the replication terminus. Thus, early-replicated markers on the multiple-branched chromosomes continue to separate soon after replication to form separate protonucleoids, even though they are not segregated into different daughter cells until later generations. The segregation pattern follows the pattern of chromosome replication and does not follow the cell division cycle. No extensive cohesion of sister DNA regions was seen at any growth rate. We conclude that segregation is driven by the progression of the replication forks.

  7. Dynamics of Escherichia coli Chromosome Segregation during Multifork Replication▿

    Science.gov (United States)

    Nielsen, Henrik J.; Youngren, Brenda; Hansen, Flemming G.; Austin, Stuart

    2007-01-01

    Slowly growing Escherichia coli cells have a simple cell cycle, with replication and progressive segregation of the chromosome completed before cell division. In rapidly growing cells, initiation of replication occurs before the previous replication rounds are complete. At cell division, the chromosomes contain multiple replication forks and must be segregated while this complex pattern of replication is still ongoing. Here, we show that replication and segregation continue in step, starting at the origin and progressing to the replication terminus. Thus, early-replicated markers on the multiple-branched chromosomes continue to separate soon after replication to form separate protonucleoids, even though they are not segregated into different daughter cells until later generations. The segregation pattern follows the pattern of chromosome replication and does not follow the cell division cycle. No extensive cohesion of sister DNA regions was seen at any growth rate. We conclude that segregation is driven by the progression of the replication forks. PMID:17905986

  8. Are chromosomal imbalances important in cancer?

    Science.gov (United States)

    Stallings, Raymond L

    2007-06-01

    Tumor-specific patterns of large-scale chromosomal imbalances characterize most forms of cancer. Based on evidence primarily from neuroblastomas, it can be argued that large-scale chromosomal imbalances are crucial for tumor pathogenesis and have an impact on the global transcriptional profile of cancer cells, and that some imbalances even initiate cancer. The genes and genetic pathways that have been dysregulated by such imbalances remain surprisingly elusive. Many genes are affected by the regions of gain and loss, and there are complex interactions and relationships that occur between these genes, hindering their identification. The study of untranslated RNA sequences, such as microRNAs, is in its infancy, and it is likely that such sequences are also dysregulated by chromosomal imbalance, contributing to pathogenesis.

  9. Inactivation of Clostridium difficile spores by microwave irradiation.

    Science.gov (United States)

    Ojha, Suvash Chandra; Chankhamhaengdecha, Surang; Singhakaew, Sombat; Ounjai, Puey; Janvilisri, Tavan

    2016-04-01

    Spores are a potent agent for Clostridium difficile transmission. Therefore, factors inhibiting spores have been of continued interest. In the present study, we investigated the influence of microwave irradiation in addition to conductive heating for C. difficile spore inactivation in aqueous suspension. The spores of 15 C. difficile isolates from different host origins were exposed to conductive heating and microwave irradiation. The complete inhibition of spore viability at 10(7) CFU/ml was encountered following microwave treatment at 800 W for 60 s, but was not observed in the conductive-heated spores at the same time-temperature exposure. The distinct patterns of ultrastructural alterations following microwave and conductive heat treatment were observed and the degree of damages by microwave was in the exposure time-dependent manner. Microwave would therefore be a simple and time-efficient tool to inactivate C. difficile spores, thus reducing the risk of C. difficile transmission.

  10. Chromosomal gene movements reflect the recent origin and biology of therian sex chromosomes.

    Directory of Open Access Journals (Sweden)

    Lukasz Potrzebowski

    2008-04-01

    Full Text Available Mammalian sex chromosomes stem from ancestral autosomes and have substantially differentiated. It was shown that X-linked genes have generated duplicate intronless gene copies (retrogenes on autosomes due to this differentiation. However, the precise driving forces for this out-of-X gene "movement" and its evolutionary onset are not known. Based on expression analyses of male germ-cell populations, we here substantiate and extend the hypothesis that autosomal retrogenes functionally compensate for the silencing of their X-linked housekeeping parental genes during, but also after, male meiotic sex chromosome inactivation (MSCI. Thus, sexually antagonistic forces have not played a major role for the selective fixation of X-derived gene copies in mammals. Our dating analyses reveal that although retrogenes were produced ever since the common mammalian ancestor, selectively driven retrogene export from the X only started later, on the placental mammal (eutherian and marsupial (metatherian lineages, respectively. Together, these observations suggest that chromosome-wide MSCI emerged close to the eutherian-marsupial split approximately 180 million years ago. Given that MSCI probably reflects the spread of the recombination barrier between the X and Y, crucial for their differentiation, our data imply that these chromosomes became more widely differentiated only late in the therian ancestor, well after the divergence of the monotreme lineage. Thus, our study also provides strong independent support for the recent notion that our sex chromosomes emerged, not in the common ancestor of all mammals, but rather in the therian ancestor, and therefore are much younger than previously thought.

  11. Vibrio chromosomes share common history

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    Gevers Dirk

    2010-05-01

    Full Text Available Abstract Background While most gamma proteobacteria have a single circular chromosome, Vibrionales have two circular chromosomes. Horizontal gene transfer is common among Vibrios, and in light of this genetic mobility, it is an open question to what extent the two chromosomes themselves share a common history since their formation. Results Single copy genes from each chromosome (142 genes from chromosome I and 42 genes from chromosome II were identified from 19 sequenced Vibrionales genomes and their phylogenetic comparison suggests consistent phylogenies for each chromosome. Additionally, study of the gene organization and phylogeny of the respective origins of replication confirmed the shared history. Conclusions Thus, while elements within the chromosomes may have experienced significant genetic mobility, the backbones share a common history. This allows conclusions based on multilocus sequence analysis (MLSA for one chromosome to be applied equally to both chromosomes.

  12. The Transient Inactivation of the Master Cell Cycle Phosphatase Cdc14 Causes Genomic Instability in Diploid Cells of Saccharomyces cerevisiae

    Science.gov (United States)

    Quevedo, Oliver; Ramos-Pérez, Cristina; Petes, Thomas D.; Machín, Félix

    2015-01-01

    Genomic instability is a common feature found in cancer cells . Accordingly, many tumor suppressor genes identified in familiar cancer syndromes are involved in the maintenance of the stability of the genome during every cell division and are commonly referred to as caretakers. Inactivating mutations and epigenetic silencing of caretakers are thought to be the most important mechanisms that explain cancer-related genome instability. However, little is known of whether transient inactivation of caretaker proteins could trigger genome instability and, if so, what types of instability would occur. In this work, we show that a brief and reversible inactivation, during just one cell cycle, of the key phosphatase Cdc14 in the model organism Saccharomyces cerevisiae is enough to result in diploid cells with multiple gross chromosomal rearrangements and changes in ploidy. Interestingly, we observed that such transient loss yields a characteristic fingerprint whereby trisomies are often found in small-sized chromosomes, and gross chromosome rearrangements, often associated with concomitant loss of heterozygosity, are detected mainly on the ribosomal DNA-bearing chromosome XII. Taking into account the key role of Cdc14 in preventing anaphase bridges, resetting replication origins, and controlling spindle dynamics in a well-defined window within anaphase, we speculate that the transient loss of Cdc14 activity causes cells to go through a single mitotic catastrophe with irreversible consequences for the genome stability of the progeny. PMID:25971663

  13. Adaptive evolution of genes duplicated from the Drosophila pseudoobscura neo-X chromosome.

    Science.gov (United States)

    Meisel, Richard P; Hilldorfer, Benedict B; Koch, Jessica L; Lockton, Steven; Schaeffer, Stephen W

    2010-08-01

    Drosophila X chromosomes are disproportionate sources of duplicated genes, and these duplications are usually the result of retrotransposition of X-linked genes to the autosomes. The excess duplication is thought to be driven by natural selection for two reasons: X chromosomes are inactivated during spermatogenesis, and the derived copies of retroposed duplications tend to be testis expressed. Therefore, autosomal derived copies of retroposed genes provide a mechanism for their X-linked paralogs to "escape" X inactivation. Once these duplications have fixed, they may then be selected for male-specific functions. Throughout the evolution of the Drosophila genus, autosomes have fused with X chromosomes along multiple lineages giving rise to neo-X chromosomes. There has also been excess duplication from the two independent neo-X chromosomes that have been examined--one that occurred prior to the common ancestor of the willistoni species group and another that occurred along the lineage leading to Drosophila pseudoobscura. To determine what role natural selection plays in the evolution of genes duplicated from the D. pseudoobscura neo-X chromosome, we analyzed DNA sequence divergence between paralogs, polymorphism within each copy, and the expression profiles of these duplicated genes. We found that the derived copies of all duplicated genes have elevated nonsynonymous polymorphism, suggesting that they are under relaxed selective constraints. The derived copies also tend to have testis- or male-biased expression profiles regardless of their chromosome of origin. Genes duplicated from the neo-X chromosome appear to be under less constraints than those duplicated from other chromosome arms. We also find more evidence for historical adaptive evolution in genes duplicated from the neo-X chromosome, suggesting that they are under a unique selection regime in which elevated nonsynonymous polymorphism provides a large reservoir of functional variants, some of which are fixed

  14. Evolution and survival on eutherian sex chromosomes.

    Directory of Open Access Journals (Sweden)

    Melissa A Wilson

    2009-07-01

    Full Text Available Since the two eutherian sex chromosomes diverged from an ancestral autosomal pair, the X has remained relatively gene-rich, while the Y has lost most of its genes through the accumulation of deleterious mutations in nonrecombining regions. Presently, it is unclear what is distinctive about genes that remain on the Y chromosome, when the sex chromosomes acquired their unique evolutionary rates, and whether X-Y gene divergence paralleled that of paralogs located on autosomes. To tackle these questions, here we juxtaposed the evolution of X and Y homologous genes (gametologs in eutherian mammals with their autosomal orthologs in marsupial and monotreme mammals. We discovered that genes on the X and Y acquired distinct evolutionary rates immediately following the suppression of recombination between the two sex chromosomes. The Y-linked genes evolved at higher rates, while the X-linked genes maintained the lower evolutionary rates of the ancestral autosomal genes. These distinct rates have been maintained throughout the evolution of X and Y. Specifically, in humans, most X gametologs and, curiously, also most Y gametologs evolved under stronger purifying selection than similarly aged autosomal paralogs. Finally, after evaluating the current experimental data from the literature, we concluded that unique mRNA/protein expression patterns and functions acquired by Y (versus X gametologs likely contributed to their retention. Our results also suggest that either the boundary between sex chromosome strata 3 and 4 should be shifted or that stratum 3 should be divided into two strata.

  15. Dynamic organization of chromosomal DNA in Escherichia coli.

    Science.gov (United States)

    Niki, H; Yamaichi, Y; Hiraga, S

    2000-01-15

    We have revealed the subcellular localization of different DNA segments that are located at approximately 230-kb intervals on the Escherichia coli chromosome using fluorescence in situ hybridization (FISH). The series of chromosome segments is localized within the cell in the same order as the chromosome map. The large chromosome region including oriC shows similar localization patterns, which we call the Ori domain. In addition, the localization pattern of the large segment including dif is characteristic of the replication terminus region. The segment also shows similar localization patterns, which we call the Ter domain. In newborn cells, Ori and Ter domains of the chromosome are differentially localized near opposite cell poles. Subsequently, in the B period, the Ori domain moves toward mid-cell before the initiation of replication, and the Ter domain tends to relocate at mid-cell. An inversion mutant, in which the Ter domain is located close to oriC, shows abnormal subcellular localization of ori and dif segments, resulting in frequent production of anucleate cells. These studies thus suggest that the E. coli chromosome is organized to form a compacted ring structure with the Ori and Ter domains; these domains participate in the cell cycle-dependent localization of the chromosome.

  16. Status of dosage compensation of X chromosome in bovine genome.

    Science.gov (United States)

    Ka, Sojeong; Ahn, Hyeonju; Seo, Minseok; Kim, Heebal; Kim, Jin Nam; Lee, Hyun-Jeong

    2016-08-01

    Dosage compensation system with X chromosome upregulation and inactivation have evolved to overcome the genetic imbalance between sex chromosomes in both male and female of mammals. Although recent development of chromosome-wide technologies has allowed us to test X upregulation, discrete data processing and analysis methods draw disparate conclusions. A series of expression studies revealed status of dosage compensation in some species belonging to monotremes, marsupials, rodents and primates. However, X upregulation in the Artiodactyla order including cattle have not been studied yet. In this study, we surveyed the genome-wide transcriptional upregulation in X chromosome in cattle RNA-seq data using different gene filtration methods. Overall examination of RNA-seq data revealed that X chromosome in the pituitary gland expressed more genes than in other peripheral tissues, which was consistent with the previous results observed in human and mouse. When analyzed with globally expressed genes, a median X:A expression ratio was 0.94. The ratio of 1-to-1 ortholog genes between chicken and mammals, however, showed considerable reduction to 0.68. These results indicate that status of dosage compensation for cattle is not deviated from those found in rodents and primate, and this is consistent with the evolutionary history of cattle.

  17. Hypermethylated Chromosome Regions in Nine Fish Species with Heteromorphic Sex Chromosomes.

    Science.gov (United States)

    Schmid, Michael; Steinlein, Claus; Yano, Cassia F; Cioffi, Marcelo B

    2015-01-01

    Sites and amounts of 5-methylcytosine (5-MeC)-rich chromosome regions were detected in the karyotypes of 9 Brazilian species of Characiformes fishes by indirect immunofluorescence using a monoclonal anti-5-MeC antibody. These species, belonging to the genera Leporinus, Triportheus and Hoplias, are characterized by highly differentiated and heteromorphic ZW and XY sex chromosomes. In all species, the hypermethylated regions are confined to constitutive heterochromatin. The number and chromosome locations of hypermethylated heterochromatic regions in the karyotypes are constant and species-specific. Generally, heterochromatic regions that are darkly stained by the C-banding technique are distinctly hypermethylated, but several of the brightly fluorescing hypermethylated regions merely exhibit moderate or faint C-banding. The ZW and XY sex chromosomes of all 9 analyzed species also show species-specific heterochromatin hypermethylation patterns. The analysis of 5-MeC-rich chromosome regions contributes valuable data for comparative cytogenetics of closely related species and highlights the dynamic process of differentiation operating in the repetitive DNA fraction of sex chromosomes.

  18. Cytological alteration of cultured rat liver cells by 3'-methyl-4-dimethylaminoazobenzene with special reference to chromosome changes, changes of growth patterns at a colony level and alpha-fetoprotein production.

    Directory of Open Access Journals (Sweden)

    Tokiwa,Takayoshi

    1980-06-01

    Full Text Available A near diploid clone derived from a rat liver cell line was continuously treated with various concentrations of 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB in culture. By treatment with 2.8 micrograms/ml, cells with 41 chromosomes formed a mode and which then shifted to 39. The chromosome numbers of cells treated with 5.4 micrograms/ml were widely distributed at early stages, but later the mode shifted to hypotetraploid region. Untreated control cells were confirmed as near diploid. Increased plating efficiency by 3'-Me-DAB as well as the appearance of large sized colonies was obtained. The production of alpha-fetoprotein (AFP by the cells was slightly enhanced by treatment with 3'-Me-DAB. The cells treated with and without 3'-Me-DAB did not produce any tumor in rats 6 months after their intraperitoneal injection.

  19. Dispensability of the SAC Depends on the Time Window Required by Aurora B to Ensure Chromosome Biorientation

    Science.gov (United States)

    Monje-Casas, Fernando

    2015-01-01

    Aurora B and the spindle assembly checkpoint (SAC) collaborate to ensure the proper biorientation of chromosomes during mitosis. However, lack of Aurora B activity and inactivation of the SAC have a very different impact on chromosome segregation. This is most evident in Saccharomyces cerevisiae, since in this organism the lack of Aurora B is lethal and leads to severe aneuploidy problems, while the SAC is dispensable under normal growth conditions and mutants in this checkpoint do not show evident chromosome segregation defects. We demonstrate that the efficient repair of incorrect chromosome attachments by Aurora B during the initial stages of spindle assembly in budding yeast determines the lack of chromosome segregation defects in SAC mutants, and propose that the differential time window that Aurora B kinase requires to establish chromosome biorientation is the key factor that determines why some cells are more dependent on a functional SAC than others. PMID:26661752

  20. The Philadelphia chromosome in leukemogenesis

    Institute of Scientific and Technical Information of China (English)

    ZhiJieKang; JinSongYan; QuentinLiu; YuFeiLiu; LingZhiXu; ZiJieLong; DanHuang; YaYang; BingLiu; JiuXingFeng; YuJiaPan

    2016-01-01

    The truncated chromosome 22 that results from the reciprocal translocation t(9;22)(q34;q11) is known as the Phila‑delphia chromosome (Ph) and is a hallmark of chronic myeloid leukemia (CML). In leukemia cells, Ph not only impairs the physiological signaling pathways but also disrupts genomic stability. This aberrant fusion gene encodes the breakpoint cluster region‑proto‑oncogene tyrosine‑protein kinase (BCR‑ABL1) oncogenic protein with persistently enhanced tyrosine kinase activity. The kinase activity is responsible for maintaining proliferation, inhibiting differentia‑tion, and conferring resistance to cell death. During the progression of CML from the chronic phase to the accelerated phase and then to the blast phase, the expression patterns of different BCR‑ABL1 transcripts vary. Each BCR‑ABL1 transcript is present in a distinct leukemia phenotype, which predicts both response to therapy and clinical outcome. Besides CML, the Ph is found in acute lymphoblastic leukemia, acute myeloid leukemia, and mixed‑phenotype acute leukemia. Here, we provide an overview of the clinical presentation and cellular biology of different phenotypes of Ph‑positive leukemia and highlight key ifndings regarding leukemogenesis.

  1. Chromosomal replicons of higher plants

    Energy Technology Data Exchange (ETDEWEB)

    Van' t Hof, J.

    1987-03-16

    This brief discussion of replicons of higher plants offers a glimpse into the properties of chromosomal DNA replication. It gives evidence that the S phase of unrelated plant species is comprised of temporally ordered replicon families that increase in number with genome size. This orderly process, which assures a normal inheritance of genetic material to recipient daughter cells, is maintained at the level of replicon clusters by two mutually exclusive mechanisms, one involving the rate at which single replicons replicate their allotment of DNA, and another by means of the tempo-pause. The same two mechanisms are used by cells to alter the pattern of chromosomal DNA replication just prior to and during normal development. Both mechanisms are genetically determined and produce genetic effects when disturbed of disrupted by additional non-conforming DNAs. Further insight into how these two mechanisms operate requires more molecular information about the nature of replicons and the factors that govern when a replicon family replicates. Plant material is a rich and ideal source for this information just awaiting exploitation. 63 refs.

  2. Photodynamic Inactivation of Mammalian Viruses and Bacteriophages

    Directory of Open Access Journals (Sweden)

    Liliana Costa

    2012-06-01

    Full Text Available Photodynamic inactivation (PDI has been used to inactivate microorganisms through the use of photosensitizers. The inactivation of mammalian viruses and bacteriophages by photosensitization has been applied with success since the first decades of the last century. Due to the fact that mammalian viruses are known to pose a threat to public health and that bacteriophages are frequently used as models of mammalian viruses, it is important to know and understand the mechanisms and photodynamic procedures involved in their photoinactivation. The aim of this review is to (i summarize the main approaches developed until now for the photodynamic inactivation of bacteriophages and mammalian viruses and, (ii discuss and compare the present state of the art of mammalian viruses PDI with phage photoinactivation, with special focus on the most relevant mechanisms, molecular targets and factors affecting the viral inactivation process.

  3. Photodynamic inactivation of mammalian viruses and bacteriophages.

    Science.gov (United States)

    Costa, Liliana; Faustino, Maria Amparo F; Neves, Maria Graça P M S; Cunha, Angela; Almeida, Adelaide

    2012-07-01

    Photodynamic inactivation (PDI) has been used to inactivate microorganisms through the use of photosensitizers. The inactivation of mammalian viruses and bacteriophages by photosensitization has been applied with success since the first decades of the last century. Due to the fact that mammalian viruses are known to pose a threat to public health and that bacteriophages are frequently used as models of mammalian viruses, it is important to know and understand the mechanisms and photodynamic procedures involved in their photoinactivation. The aim of this review is to (i) summarize the main approaches developed until now for the photodynamic inactivation of bacteriophages and mammalian viruses and, (ii) discuss and compare the present state of the art of mammalian viruses PDI with phage photoinactivation, with special focus on the most relevant mechanisms, molecular targets and factors affecting the viral inactivation process.

  4. The cohesion stabilizer sororin favors DNA repair and chromosome segregation during mouse oocyte meiosis.

    Science.gov (United States)

    Huang, Chun-Jie; Yuan, Yi-Feng; Wu, Di; Khan, Faheem Ahmed; Jiao, Xiao-Fei; Huo, Li-Jun

    2017-03-01

    Maintenance and timely termination of cohesion on chromosomes ensures accurate chromosome segregation to guard against aneuploidy in mammalian oocytes and subsequent chromosomally abnormal pregnancies. Sororin, a cohesion stabilizer whose relevance in antagonizing the anti-cohesive property of Wings-apart like protein (Wapl), has been characterized in mitosis; however, the role of Sororin remains unclear during mammalian oocyte meiosis. Here, we show that Sororin is required for DNA damage repair and cohesion maintenance on chromosomes, and consequently, for mouse oocyte meiotic program. Sororin is constantly expressed throughout meiosis and accumulates on chromatins at germinal vesicle (GV) stage/G2 phase. It localizes onto centromeres from germinal vesicle breakdown (GVBD) to metaphase II stage. Inactivation of Sororin compromises the GVBD and first polar body extrusion (PBE). Furthermore, Sororin inactivation induces DNA damage indicated by positive γH2AX foci in GV oocytes and precocious chromatin segregation in MII oocytes. Finally, our data indicate that PlK1 and MPF dissociate Sororin from chromosome arms without affecting its centromeric localization. Our results define Sororin as a determinant during mouse oocyte meiotic maturation by favoring DNA damage repair and chromosome separation, and thereby, maintaining the genome stability and generating haploid gametes.

  5. Supernumerary ring chromosome: an etiology for Pallister-Killian syndrome?

    Science.gov (United States)

    Lloveras, E; Canellas, A; Cirigliano, V; Català, V; Cerdan, C; Plaja, A

    2013-01-01

    Characterization of marker chromosomes before the introduction of array CGH (aCGH) assays was only based on their banding patterns (G, C, and NOR staining) and fluorescent in situ hybridization techniques. The use of aCGH greatly improves the identification of marker chromosomes in some cases. We describe an atypical case of Pallister-Killian syndrome (PKS) detected at prenatal diagnosis with a very unusual cytogenetic presentation: a supernumerary ring chromosome including two copies of 12p. A similar anomaly described in a postnatal patient suggests ring chromosome as a possible cause of PKS. Extra ring chromosomes might be a more common etiology for PKS than previously thought, given the difficulty in their characterization before the advent of aCGH.

  6. Chromosome numbers in Bromeliaceae

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    Cotias-de-Oliveira Ana Lúcia Pires

    2000-01-01

    Full Text Available The present study reports chromosome numbers of 17 species of Bromeliaceae, belonging to the genera Encholirium, Bromelia, Orthophytum, Hohenbergia, Billbergia, Neoglaziovia, Aechmea, Cryptanthus and Ananas. Most species present 2n = 50, however, Bromelia laciniosa, Orthophytum burle-marxii and O. maracasense are polyploids with 2n = 150, 2n = 100 and 2n = 150, respectively, while for Cryptanthus bahianus, 2n = 34 + 1-4B. B chromosomes were observed in Bromelia plumieri and Hohenbergia aff. utriculosa. The chromosome number of all species was determined for the first time, except for Billbergia chlorosticta and Cryptanthus bahianus. Our data supports the hypothesis of a basic number of x = 25 for the Bromeliaceae family and decreasing aneuploidy in the genus Cryptanthus.

  7. Those amazing dinoflagellate chromosomes

    Institute of Scientific and Technical Information of China (English)

    PETER J RIZZO

    2003-01-01

    Dinoflagellates are a very large and diverse group of eukaryotic algae that play a major role in aquatic food webs of both fresh water and marine habitats. Moreover, the toxic members of this group pose a health threat in the form of red tides. Finally, dinoflagellates are of great evolutionary importance,because of their taxonomic position, and their unusual chromosome structure and composition. While the cytoplasm of dinoflagellates is typically eukaryotic, the nucleus is unique when compared to the nucleus of other eukaryotes. More specifically, while the chromosomes of all other eukaryotes contain histones,dinoflagellate chromosomes lack histones completely. There are no known exceptions to this observation: all dinoflagellates lack histones, and all other eukaryotes contain histones. Nevertheless, dinoflagellates remain a relatively unstudied group of eukaryotes.

  8. Tumor-suppressor genes that escape from X-inactivation contribute to cancer sex bias.

    Science.gov (United States)

    Dunford, Andrew; Weinstock, David M; Savova, Virginia; Schumacher, Steven E; Cleary, John P; Yoda, Akinori; Sullivan, Timothy J; Hess, Julian M; Gimelbrant, Alexander A; Beroukhim, Rameen; Lawrence, Michael S; Getz, Gad; Lane, Andrew A

    2017-01-01

    There is a striking and unexplained male predominance across many cancer types. A subset of X-chromosome genes can escape X-inactivation, which would protect females from complete functional loss by a single mutation. To identify putative 'escape from X-inactivation tumor-suppressor' (EXITS) genes, we examined somatic alterations from >4,100 cancers across 21 tumor types for sex bias. Six of 783 non-pseudoautosomal region (PAR) X-chromosome genes (ATRX, CNKSR2, DDX3X, KDM5C, KDM6A, and MAGEC3) harbored loss-of-function mutations more frequently in males (based on a false discovery rate genes (Fisher's exact P genes that escape X-inactivation were observed in combined analysis across many cancers and in several individual tumor types, suggesting a generalized phenomenon. We conclude that biallelic expression of EXITS genes in females explains a portion of the reduced cancer incidence in females as compared to males across a variety of tumor types.

  9. Behavioral inspiratory inhibition: inactivated and activated respiratory cells.

    Science.gov (United States)

    Orem, J

    1989-11-01

    1. Eleven adult cats were trained to stop inspiration in response to a conditioning stimulus. The conditioning stimuli were presented at the onset of inspiration at intervals of approximately 20-30 s. Intratracheal pressures, diaphragmatic activity, and the extracellular activity of single medullary respiratory neurons were recorded while the animals performed this response. 2. Inactivation of the diaphragm to the conditioning stimuli occurred at latencies that varied from 40 to 110 ms and averaged 74 +/- 32 (SD) ms. 3. The subjects of this report are 38 inspiratory neurons that were inactivated and 19 cells that were activated when inspiration was stopped behaviorally. These cells were located in the region of n. ambiguus and the ventrolateral n. of tractus solitarius. 4. The inspiratory cells that were inactivated behaviorally had the following characteristics: 1) Most had an augmenting inspiratory profile with (n = 14) or without (n = 9) postinspiratory activity. Other types were inspiratory throughout (n = 5), decrementing inspiratory (n = 3), tonic inspiratory (n = 4), early inspiratory (n = 2), and expiratory-inspiratory (n = 1). 2) Their mean discharge rate was 39 +/- 2.7 (SE) Hz. 3) The latency of their inactivation in response to the task averaged 81 +/- 4.9 (SE) ms, and 4) Their activity corresponded closely to breathing not only during the behavioral response but also during eupnea (eta 2 = 0.62 +/- 0.04, mean +/- SE) and respiratory acts such as sneezing, sniffing, meowing, and purring. 5. The cells that were activated when inspiration was stopped behaviorally had the following characteristics. 1) As a group, they had discharge profiles related to every phase of the respiratory cycle. 2) They were recorded in the same region as, and often simultaneously with, respiratory cells that were inactivated. 3) Their activity patterns were highly variable such that the signal strength and consistency of the respiratory component of that activity were weak (eta 2

  10. Chromosomes Progress to Metaphase in Multiple Discrete Steps via Global Compaction/Expansion Cycles.

    Science.gov (United States)

    Liang, Zhangyi; Zickler, Denise; Prentiss, Mara; Chang, Frederick S; Witz, Guillaume; Maeshima, Kazuhiro; Kleckner, Nancy

    2015-05-21

    Mammalian mitotic chromosome morphogenesis was analyzed by 4D live-cell and snapshot deconvolution fluorescence imaging. Prophase chromosomes, whose organization was previously unknown, are revealed to comprise co-oriented sister linear loop arrays displayed along a single, peripheral, regularly kinked topoisomerase II/cohesin/condensin II axis. Thereafter, rather than smooth, progressive compaction as generally envisioned, progression to metaphase is a discontinuous process involving chromosome expansion as well as compaction. At late prophase, dependent on topoisomerase II and with concomitant cohesin release, chromosomes expand, axes split and straighten, and chromatin loops transit to a radial disposition around now-central axes. Finally, chromosomes globally compact, giving the metaphase state. These patterns are consistent with the hypothesis that the molecular events of chromosome morphogenesis are governed by accumulation and release of chromosome stress, created by chromatin compaction and expansion. Chromosome state could evolve analogously throughout the cell cycle.

  11. Mental retardation and Ullrich-Turner syndrome in cases with 45,X/46,X, +mar: Additional support for the loss of the X-inactivation center hypothesis

    Energy Technology Data Exchange (ETDEWEB)

    Cole, H.; Huang, B.; Brown, J.; Howard-Peebles, P.N.; Black, S.H.; Jackson-Cook, C. [Virginia Commonwealth Univ., Richmond, VA (United States); Salbert, B.A. [Children`s Mercy Hospital, Kansas City, MO (United States); Febles, O.R. [Hialeah Hospital, FL (United States); Stevens, C.A. [Univ. of Tennessee, Chattanooga, TN (United States)

    1994-08-15

    Four cases having mosaicism for a small marker or ring [45,X/46,X,+mar or 45,X/46,X,+r] chromosome were ascertained following cytogenetic studies requested because of minor anomalies (cases 1, 3, and 4) and/or short stature (cases 2 and 4). While all 4 cases had traits typical of Ullrich-Turner syndrome (UTS), cases 1, 3, and 4 had manifestations not usually present in UTS, including unusual facial appearance, mental retardation/developmental delay (MR/DD) (cases 3 and 4), and syndactylies (case 1). Using fluorescence in situ hybridization (FISH), each of the markers in these 4 cases was identified as having been derived from an X chromosome. Replication studies demonstrated a probable early replication pattern for the mar/r(X) in cases 1, 3, and 4, while the marker in case 2 was apparently late replicating. To date, 41 individuals having mosaicism for a small mar/r(X) chromosome have been described. Interestingly, most of the 14 individuals having a presumedly active mar/r(X) demonstrated clinical findings atypical of UTS, including abnormal facial changes (11) and MR/DD (13). MR was noted most frequently in those cases having at least 50% mosaicism for the marker or ring. In contrast, atypical UTS facial appearance or MR/DD was not noted in 14 of the 16 cases with UTS who carried a probable late replicating marker or ring. In conclusion, although the phenotype of 45,S/46,X, mar/r(X) individuals appears to be influenced by the genetic content and degree of mosaicism for the mar/r(X), the most significant factor associated with MR/DD appears to be the activity status of the mar/r(X) chromosome. Thus, our 4 cases provide further support for the hypothesis that a lack of inactivation of a small mar/r(X) chromosome may be a factor leading to the MR and other phenotypic abnormalities seen in this subset of individuals having atypical UTS. 46 refs., 6 figs., 3 tabs.

  12. Chromosomal rearrangements in cattle and pigs revealed by chromosome microdissection and chromosome painting

    Directory of Open Access Journals (Sweden)

    Yerle Martine

    2003-11-01

    Full Text Available Abstract A pericentric inversion of chromosome 4 in a boar, as well as a case of (2q-;5p+ translocation mosaicism in a bull were analysed by chromosome painting using probes generated by conventional microdissection. For the porcine inversion, probes specific for p arms and q arms were produced and hybridised simultaneously on metaphases of a heterozygote carrier. In the case of the bovine translocation, two whole chromosome probes (chromosome 5, and derived chromosome 5 were elaborated and hybridised independently on chromosomal preparations of the bull who was a carrier of the mosaic translocation. The impossibility of differentiating chromosomes 2 and der(2 from other chromosomes of the metaphases did not allow the production of painting probes for these chromosomes. For all experiments, the quality of painting was comparable to that usually observed with probes obtained from flow-sorted chromosomes. The results obtained allowed confirmation of the interpretations proposed with G-banding karyotype analyses. In the bovine case, however, the reciprocity of the translocation could not be proven. The results presented in this paper show the usefulness of the microdissection technique for characterising chromosomal rearrangements in species for which commercial probes are not available. They also confirmed that the main limiting factor of the technique is the quality of the chromosomal preparations, which does not allow the identification of target chromosomes or chromosome fragments in all cases.

  13. Deficit of mito-nuclear genes on the human X chromosome predates sex chromosome formation

    OpenAIRE

    Dean, R; Zimmer, F.; Mank, J E

    2015-01-01

    Two taxa studied to date, the therian mammals and Caenorhaditis elegans, display under-representations of mito-nuclear genes (mt-N genes, nuclear genes whose products are imported to and act within the mitochondria) on their X chromosomes. This pattern has been interpreted as the result of sexual conflict driving mt-N genes off of the X chromosome. However, studies in several other species have failed to detect a convergent biased distribution of sex-linked mt-N genes, leading to questions ov...

  14. Molecular mapping of chromosomes 17 and X

    Energy Technology Data Exchange (ETDEWEB)

    Barker, D.F.

    1989-01-01

    The basic aims of this project are the construction of high density genetic maps of chromosomes 17 and X and the utilization of these maps for the subsequent isolation of a set of physically overlapping DNA segment clones. The strategy depends on the utilization of chromosome specific libraries of small (1--15 kb) segments from each of the two chromosomes. Since the time of submission of our previous progress report, we have refined the genetic map of markers which we had previously isolated for chromosome 17. We have completed our genetic mapping in CEPH reference and NF1 families of 15 markers in the pericentric region of chromosome 17. Physical mapping results with three probes, were shown be in very close genetic proximity to the NF1 gene, with respect to two translocation breakpoints which disrupt the activity of the gene. All three of the probes were found to lie between the centromere and the most proximal translocation breakpoint, providing important genetic markers proximal to the NF1 gene. Our primary focus has shifted to the X chromosome. We have isolated an additional 30 polymorphic markers, bringing the total number we have isolated to over 80. We have invested substantial effort in characterizing the polymorphisms at each of these loci and constructed plasmid subclones which reveal the polymorphisms for nearly all of the loci. These subclones are of practical value in that they produce simpler and stronger patterns on human genomic Southern blots, thus improving the efficiency of the genetic mapping experiments. These subclones may also be of value for deriving DNA sequence information at each locus, necessary for establishing polymerase chain reaction primers specific for each locus. Such information would allow the use of each locus as a sequence tagged site.

  15. Chromosomes of Protists: The crucible of evolution.

    Science.gov (United States)

    Soyer-Gobillard, Marie-Odile; Dolan, Michael F

    2015-12-01

    As early as 1925, the great protozoologist Edouard Chatton classified microorganisms into two categories, the prokaryotic and the eukaryotic microbes, based on light microscopical observation of their nuclear organization. Now, by means of transmission electron microscopy, we know that prokaryotic microbes are characterized by the absence of nuclear envelope surrounding the bacterial chromosome, which is more or less condensed and whose chromatin is deprived of histone proteins but presents specific basic proteins. Eukaryotic microbes, the protists, have nuclei surrounded by a nuclear envelope and have chromosomes more or less condensed, with chromatin-containing histone proteins organized into nucleosomes. The extraordinary diversity of mitotic systems presented by the 36 phyla of protists (according to Margulis et al., Handbook of Protoctista, 1990) is in contrast to the relative homogeneity of their chromosome structure and chromatin components. Dinoflagellates are the exception to this pattern. The phylum is composed of around 2000 species, and characterized by unique features including their nucleus (dinokaryon), dinomitosis, chromosome organization and chromatin composition. Although their DNA synthesis is typically eukaryotic, dinoflagellates are the only eukaryotes in which the chromatin, organized into quasi-permanently condensed chromosomes, is in some species devoid of histones and nucleosomes. In these cases, their chromatin contains specific DNA-binding basic proteins. The permanent compaction of their chromosomes throughout the cell cycle raises the question of the modalities of their division and their transcription. Successful in vitro reconstitution of nucleosomes using dinoflagellate DNA and heterologous corn histones raises questions about dinoflagellate evolution and phylogeny. [Int Microbiol 18(4):209-216 (2015)].

  16. Hierarchical radial and polar organisation of chromosomes in human sperm.

    Science.gov (United States)

    Millan, N M; Lau, P; Hann, M; Ioannou, D; Hoffman, D; Barrionuevo, M; Maxson, W; Ory, S; Tempest, H G

    2012-10-01

    It is well established that chromosomes occupy distinct positions within the interphase nuclei, conferring a potential functional implication to the genome. In addition, alterations in the nuclear organisation patterns have been associated with disease phenotypes (e.g. cancer or laminopathies). The human sperm is the smallest cell in the body with specific DNA packaging and the mission of delivering the paternal genome to the oocyte during fertilisation. Studies of nuclear organisation in the sperm have postulated nonrandom chromosome position and have proposed a chromocentre model with the centromeres facing toward the interior and the telomeres toward the periphery of the nucleus. Most studies have assessed the nuclear address in the sperm longitudinally predominantly using centromeric or telomeric probes and to a lesser extent with whole chromosome paints. To date, studies investigating the radial organisation of human sperm have been limited. The purpose of this study was to utilise whole chromosome paints for six clinically important chromosomes (18, 19, 21, 22, X, and Y) to investigate nuclear address by assessing their radial and longitudinal nuclear organisation. A total of 10,800 sperm were analysed in nine normozoospermic individuals. The results have shown nonrandom chromosome position for all chromosomes using both methods of analysis. We present novel radial and polar analysis of chromosome territory localization within the human sperm nucleus. Specifically, a hierarchical organisation was observed radially with chromosomes organised from the interior to the periphery (chromosomes 22, 21, Y, X, 19, and 18 respectively) and polar organisation from the sperm head to tail (chromosomes X, 19, Y, 22, 21, and 18, respectively). We provide evidence of defined nuclear organisation in the human sperm and discuss the function of organisation and potential possible clinical ramifications of these results in regards to male infertility and early human development.

  17. High-resolution analysis of epigenetic changes associated with X inactivation.

    Science.gov (United States)

    Marks, Hendrik; Chow, Jennifer C; Denissov, Sergei; Françoijs, Kees-Jan; Brockdorff, Neil; Heard, Edith; Stunnenberg, Hendrik G

    2009-08-01

    Differentiation of female murine ES cells triggers silencing of one X chromosome through X-chromosome inactivation (XCI). Immunofluorescence studies showed that soon after Xist RNA coating the inactive X (Xi) undergoes many heterochromatic changes, including the acquisition of H3K27me3. However, the mechanisms that lead to the establishment of heterochromatin remain unclear. We first analyze chromatin changes by ChIP-chip, as well as RNA expression, around the X-inactivation center (Xic) in female and male ES cells, and their day 4 and 10 differentiated derivatives. A dynamic epigenetic landscape is observed within the Xic locus. Tsix repression is accompanied by deposition of H3K27me3 at its promoter during differentiation of both female and male cells. However, only in female cells does an active epigenetic landscape emerge at the Xist locus, concomitant with high Xist expression. Several regions within and around the Xic show unsuspected chromatin changes, and we define a series of unusual loci containing highly enriched H3K27me3. Genome-wide ChIP-seq analyses show a female-specific quantitative increase of H3K27me3 across the X chromosome as XCI proceeds in differentiating female ES cells. Using female ES cells with nonrandom XCI and polymorphic X chromosomes, we demonstrate that this increase is specific to the Xi by allele-specific SNP mapping of the ChIP-seq tags. H3K27me3 becomes evenly associated with the Xi in a chromosome-wide fashion. A selective and robust increase of H3K27me3 and concomitant decrease in H3K4me3 is observed over active genes. This indicates that deposition of H3K27me3 during XCI is tightly associated with the act of silencing of individual genes across the Xi.

  18. Studies on chromosome karyotype, Ag-NORs and C-banding patterns of Lutjanus sebae%川纹笛鲷染色体核型、银染和C-带

    Institute of Scientific and Technical Information of China (English)

    郭明兰; 游欣欣; 苏永全; 丁少雄; 王军

    2011-01-01

    实验采用植物血凝素、秋水仙碱腹腔注射,肾细胞直接制片法分析了川纹笛鲷Lutjanus sebae染色体核型、Ag-NORs和C-带.结果表明:1)川纹笛鲷二倍体染色体数2n=48,核型公式为:2n=48t,NF=48;在第1对染色体靠近着丝粒部位有明显的次缢痕.2)染色体经快速银染后,Ag-NORs的数目在不同细胞中表现出多态性,数目1-4个,2个Ag-NORs的频率最高(占79%).在分裂相中,第1对t染色体近着丝粒的次缢痕区均出现2个银染位点(Ag-NORs阳性),且未见Ag-NORs的联合现象.3)大多数染色体的着丝粒区显示出1个深浅不同的C-带,在第1对染色体的随体区域分布有大量的结构异染色质,表现C-带强阳性.讨论了鱼类核型演化规律和Ag-NORs,C-带的发生机制,以及川纹笛鲷的进化地位.%Studies on karyotype, Ag-NORs, and C-banding of Lutjanus sebae were performed. The chromosomes were received from the head kidney by using a method of injecting with PHA and colchicines, air drying, and Giemsa staining. The results were as follows. 1) The karyotypic formula of L.sebae was 2n=48t, NF=48. Meanwhile, a pair of chromosomes, with secondary constriction near the centromere, was found on chromosome 1. 2) The Ag-NORs polymorphisms were individually specific in this fish. The silver staining pots were1-4, and the number of Ag-NORs was mainly 2 (79%). A pair of nucleolar organizer regions was observed on the secondary constriction of chromosome 1, and no Ag-NORs combination was found. 3) Centromeres of most chromosomes were C-bandings positive, and heterochromatin was detected at the satellite zone of chromosome 1. Thus, we discussed the evolution of karyotype, the developing mechanism of Ag-NORs, and C-bandings for fish. The phylogenetic condition of L. sebae was evaluated as well.

  19. Electochemical detection of chromosome translocation

    DEFF Research Database (Denmark)

    Kwasny, Dorota; Dimaki, Maria; Silahtaroglu, Asli;

    2014-01-01

    Cytogenetics is a study of the cell structure with a main focus on chromosomes content and their structure. Chromosome abnormalities, such as translocations may cause various genetic disorders and heametological malignancies. Chromosome translocations are structural rearrangements of two...... chromosomes that results in formation of derivative chromosomes with a mixed DNA sequence. The method currently used for their detection is Fluorescent In Situ Hybridization, which requires a use of expensive, fluorescently labeled probes that target the derivative chromosomes. We present here a double...... hybridization approach developed for label-free detection of the chromosome translocations. For specific translocation detection it is necessary to determine that the two DNA sequences forming a derivative chromosome are connected, which is achieved by two subsequent hybridization steps. The electrochemical...

  20. Chromosome Variations And Human Behavior

    Science.gov (United States)

    Soudek, D.

    1974-01-01

    Article focused on the science of cytogenetics, which studied the transmission of the units of heredity called chromosomes, and considered the advantage of proper diagnosis of genetic diseases, treated on the chromosomal level. (Author/RK)

  1. Ring chromosome 13

    DEFF Research Database (Denmark)

    Brandt, C A; Hertz, Jens Michael; Petersen, M B;

    1992-01-01

    A stillborn male child with anencephaly and multiple malformations was found to have the karyotype 46,XY,r(13) (p11q21.1). The breakpoint at 13q21.1, determined by high resolution banding, is the most proximal breakpoint ever reported in patients with ring chromosome 13. In situ hybridisation...

  2. Chromosomes, cancer and radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Samouhos, E.

    1983-08-01

    Some specific chromosomal abnormalities are associated with certain cancers. The earliest description of such a specific association is the one of the Philadelphia chromosome and myelogenous leukemia (1960). Other congenital karyotype abnormalities are associated with specific cancers. Examples of these are Down's syndrome with leukemia and Klinefelter's syndrome with male breast cancer. Genetic diseases of increased chromosome breakage, or of defective chromosome repair, are associated with greatly increased cancer incidence. Three such diseases have been recognized: 1) Fanconi's anemia, associated with leukemias and lymphomas, 2) Bloom's syndrome, associated with acute leukemias and lymphosarcoma, and 3) ataxia telangiectasia, associated with Hodgkin's disease, leukemia, and lymphosarcomas. Ten percent of individuals with ataxia telangiectasia will develop one of these neoplasms. Individuals with certain of these syndromes display an unusually high radiosensitivity. Radiation therapy for cancers has been fatal in patients who received as low as 3000 rad. This remarkable radiosensitivity has been quantitated in cell cultures from such cases. Evidence suggests that the apparent sensitivity may reflect subnormal ability to repair radiation damage. The rapid proliferation of information in this field stems from the interdigitation of many disciplines and specialties, including cytogenetics, cell biology, molecular biology, epidemiology, radiobiology, and several others. This paper is intended for clinicians; it presents a structured analytic scheme for correlating and classifying this multidisciplinary information as it becomes available.

  3. The Y Chromosome

    Science.gov (United States)

    Offner, Susan

    2010-01-01

    The Y chromosome is of great interest to students and can be used to teach about many important biological concepts in addition to sex determination. This paper discusses mutation, recombination, mammalian sex determination, sex determination in general, and the evolution of sex determination in mammals. It includes a student activity that…

  4. Why Chromosome Palindromes?

    Directory of Open Access Journals (Sweden)

    Esther Betrán

    2012-01-01

    Full Text Available We look at sex-limited chromosome (Y or W evolution with particular emphasis on the importance of palindromes. Y chromosome palindromes consist of inverted duplicates that allow for local recombination in an otherwise nonrecombining chromosome. Since palindromes enable intrachromosomal gene conversion that can help eliminate deleterious mutations, they are often highlighted as mechanisms to protect against Y degeneration. However, the adaptive significance of recombination resides in its ability to decouple the evolutionary fates of linked mutations, leading to both a decrease in degeneration rate and an increase in adaptation rate. Our paper emphasizes the latter, that palindromes may exist to accelerate adaptation by increasing the potential targets and fixation rates of incoming beneficial mutations. This hypothesis helps reconcile two enigmatic features of the “palindromes as protectors” view: (1 genes that are not located in palindromes have been retained under purifying selection for tens of millions of years, and (2 under models that only consider deleterious mutations, gene conversion benefits duplicate gene maintenance but not initial fixation. We conclude by looking at ways to test the hypothesis that palindromes enhance the rate of adaptive evolution of Y-linked genes and whether this effect can be extended to palindromes on other chromosomes.

  5. An evaluation of the performance of HapMap SNP data in a Shanghai Chinese population: Analyses of allele frequency, linkage disequilibrium pattern and tagging SNPs transferability on chromosome 1q21-q25

    OpenAIRE

    2008-01-01

    Abstract Background The HapMap project aimed to catalog millions of common single nucleotide polymorphisms (SNPs) in the human genome in four major populations, in order to facilitate association studies of complex diseases. To examine the transferability of Han Chinese in Beijing HapMap data to the Southern Han Chinese in Shanghai, we performed comparative analyses between genotypes from over 4,500 SNPs in a 21 Mb region on chromosome 1q21-q25 in 80 unrelated Shanghai Chinese and 45 HapMap C...

  6. Telomere dysfunction and chromosome instability

    Energy Technology Data Exchange (ETDEWEB)

    Murnane, John P., E-mail: jmurnane@radonc.ucsf.edu [Department of Radiation Oncology, University of California San Francisco, 2340 Sutter Street, San Francisco, CA 94143-1331 (United States)

    2012-02-01

    The ends of chromosomes are composed of a short repeat sequence and associated proteins that together form a cap, called a telomere, that keeps the ends from appearing as double-strand breaks (DSBs) and prevents chromosome fusion. The loss of telomeric repeat sequences or deficiencies in telomeric proteins can result in chromosome fusion and lead to chromosome instability. The similarity between chromosome rearrangements resulting from telomere loss and those found in cancer cells implicates telomere loss as an important mechanism for the chromosome instability contributing to human cancer. Telomere loss in cancer cells can occur through gradual shortening due to insufficient telomerase, the protein that maintains telomeres. However, cancer cells often have a high rate of spontaneous telomere loss despite the expression of telomerase, which has been proposed to result from a combination of oncogene-mediated replication stress and a deficiency in DSB repair in telomeric regions. Chromosome fusion in mammalian cells primarily involves nonhomologous end joining (NHEJ), which is the major form of DSB repair. Chromosome fusion initiates chromosome instability involving breakage-fusion-bridge (B/F/B) cycles, in which dicentric chromosomes form bridges and break as the cell attempts to divide, repeating the process in subsequent cell cycles. Fusion between sister chromatids results in large inverted repeats on the end of the chromosome, which amplify further following additional B/F/B cycles. B/F/B cycles continue until the chromosome acquires a new telomere, most often by translocation of the end of another chromosome. The instability is not confined to a chromosome that loses its telomere, because the instability is transferred to the chromosome donating a translocation. Moreover, the amplified regions are unstable and form extrachromosomal DNA that can reintegrate at new locations. Knowledge concerning the factors promoting telomere loss and its consequences is

  7. Deletion of an X-inactivation boundary disrupts adjacent gene silencing.

    Directory of Open Access Journals (Sweden)

    Lindsay M Horvath

    2013-11-01

    Full Text Available In mammalian females, genes on one X are largely silenced by X-chromosome inactivation (XCI, although some "escape" XCI and are expressed from both Xs. Escapees can closely juxtapose X-inactivated genes and provide a tractable model for assessing boundary function at epigenetically regulated loci. To delimit sequences at an XCI boundary, we examined female mouse embryonic stem cells carrying X-linked BAC transgenes derived from an endogenous escape locus. Previously we determined that large BACs carrying escapee Kdm5c and flanking X-inactivated transcripts are properly regulated. Here we identify two lines with truncated BACs that partially and completely delete the distal Kdm5c XCI boundary. This boundary is not required for escape, since despite integrating into regions that are normally X inactivated, transgenic Kdm5c escapes XCI, as determined by RNA FISH and by structurally adopting an active conformation that facilitates long-range preferential association with other escapees. Yet, XCI regulation is disrupted in the transgene fully lacking the distal boundary; integration site genes up to 350 kb downstream of the transgene now inappropriately escape XCI. Altogether, these results reveal two genetically separable XCI regulatory activities at Kdm5c. XCI escape is driven by a dominant element(s retained in the shortest transgene that therefore lies within or upstream of the Kdm5c locus. Additionally, the distal XCI boundary normally plays an essential role in preventing nearby genes from escaping XCI.

  8. Chromosome imbalance as a driver of sex disparity in disease.

    Science.gov (United States)

    Abramowitz, Lara K; Olivier-Van Stichelen, Stéphanie; Hanover, John A

    2014-01-01

    It has long been recognized that men and women exhibit different risks for diverse disorders ranging from metabolic to autoimmune diseases. However, the underlying causes of these disparities remain obscure. Analysis of patients with chromosomal abnormalities, including Turner syndrome (45X) and Klinefelter syndrome (47XXY), has highlighted the importance of X-linked gene dosage as a contributing factor for disease susceptibility. Escape from X-inactivation and X-linked imprinting can result in transcriptional differences between normal men and women as well as in patients with sex chromosome abnormalities. Animal models support a role for X-linked gene dosage in disease with O-linked N-acetylglucosamine transferase (OGT) emerging as a prime candidate for a pleiotropic effector. OGT encodes a highly regulated nutrient-sensing epigenetic modifier with established links to immunity, metabolism and development.

  9. [Dicentric Y chromosome].

    Science.gov (United States)

    Abdelmoula, N Bouayed; Amouri, A

    2005-01-01

    Dicentric Y chromosomes are the most common Y structural abnormalities and their influence on gonadal and somatic development is extremely variable. Here, we report the third comprehensive review of the literature concerning dicentric Y chromosomes reported since 1994. We find 78 new cases for which molecular studies (PCR or FISH) have been widely applied to investigate SRY (68% of cases), GBY, ZFY, RFS4Y, GCY and different genes at AZF region. For dic(Yq), all cases (n = 20) were mosaic for 45,X and 4 of them were also mosaic for a 46,XY cell line. When breakpoints were available (15/20 cases), they were in Yp11. 50% of cases were phenotypic female and 20% phenotypic male while 20% of cases were reported with gonadal dysgenesis. Gonadal histology was defined in 8 cases but only in one case, gonadal tissu was genetically investigated because of gonadoblastoma. For dic(Yp) (n = 55), mosaicism concerned only 45,X cell line and was found in 50 cases while the remainder five cases were homogeneous. When breakpoints were available, it was at Yq11 in 50 cases and at Yq12 in two cases. 54% of cases were phenotypic female, 26% were phenotypic male and 18% were associated with genitalia ambiguous. SRY was analyzed in 33 cases, sequenced in 9 cases and was muted in only one case. Gonads were histologically explored in 34 cases and genetically investigated in 8 cases. Gonadoblastoma was found in only two cases. Through this review, it seems that phenotype-genotype correlations are still not possible and that homogeneous studies of dic(Y) in more patients using molecular tools for structural characterization of the rearranged Y chromosome and assessment of mosaicism in many organs are necessary to clarify the basis of the phenotypic heterogeneity of dicentric Y chromosomes and then to help phenotypic prediction of such chromosome rearrangement.

  10. The chromosomal distribution of microsatellite repeats in the genome of the wolf fish Hoplias malabaricus, focusing on the sex chromosomes.

    Science.gov (United States)

    Cioffi, M B; Kejnovsky, E; Bertollo, L A C

    2011-01-01

    Distribution of 12 mono-, di- and tri-nucleotide microsatellites on the chromosomes of 2 karyomorphs with 2 distinct sex chromosome systems (a simple XX/XY - karyomorph B and a multiple X(1)X(1)X(2)X(2)/X(1)X(2)Y - karyomorph D) in Hoplias malabaricus, commonly referred to as wolf fish, was studied using their physical mapping with fluorescence in situ hybridization (FISH). The distribution patterns of different microsatellites along the chromosomes varied considerably. Strong hybridization signals were observed at subtelomeric and heterochromatic regions of several autosomes, with a different accumulation on the sex chromosomes. A massive accumulation was found in the heterochromatic region of the X chromosome of karyomorph B, whereas microsatellites were gathered at centromeres of both X chromosomes as well as in corresponding regions of the neo-Y chromosome in karyomorph D. Our findings are likely in agreement with models that predict the accumulation of repetitive DNA sequences in regions with very low recombination. This process is however in contrast with what was observed in multiple systems, where such a reduction might be facilitated by the chromosomal rearrangements that are directly associated with the origin of these systems.

  11. Sex Chromosome-wide Transcriptional Suppression and Compensatory Cis-Regulatory Evolution Mediate Gene Expression in the Drosophila Male Germline.

    Directory of Open Access Journals (Sweden)

    Emily L Landeen

    2016-07-01

    Full Text Available The evolution of heteromorphic sex chromosomes has repeatedly resulted in the evolution of sex chromosome-specific forms of regulation, including sex chromosome dosage compensation in the soma and meiotic sex chromosome inactivation in the germline. In the male germline of Drosophila melanogaster, a novel but poorly understood form of sex chromosome-specific transcriptional regulation occurs that is distinct from canonical sex chromosome dosage compensation or meiotic inactivation. Previous work shows that expression of reporter genes driven by testis-specific promoters is considerably lower-approximately 3-fold or more-for transgenes inserted into X chromosome versus autosome locations. Here we characterize this transcriptional suppression of X-linked genes in the male germline and its evolutionary consequences. Using transgenes and transpositions, we show that most endogenous X-linked genes, not just testis-specific ones, are transcriptionally suppressed several-fold specifically in the Drosophila male germline. In wild-type testes, this sex chromosome-wide transcriptional suppression is generally undetectable, being effectively compensated by the gene-by-gene evolutionary recruitment of strong promoters on the X chromosome. We identify and experimentally validate a promoter element sequence motif that is enriched upstream of the transcription start sites of hundreds of testis-expressed genes; evolutionarily conserved across species; associated with strong gene expression levels in testes; and overrepresented on the X chromosome. These findings show that the expression of X-linked genes in the Drosophila testes reflects a balance between chromosome-wide epigenetic transcriptional suppression and long-term compensatory adaptation by sex-linked genes. Our results have broad implications for the evolution of gene expression in the Drosophila male germline and for genome evolution.

  12. Sex Chromosome-wide Transcriptional Suppression and Compensatory Cis-Regulatory Evolution Mediate Gene Expression in the Drosophila Male Germline.

    Science.gov (United States)

    Landeen, Emily L; Muirhead, Christina A; Wright, Lori; Meiklejohn, Colin D; Presgraves, Daven C

    2016-07-01

    The evolution of heteromorphic sex chromosomes has repeatedly resulted in the evolution of sex chromosome-specific forms of regulation, including sex chromosome dosage compensation in the soma and meiotic sex chromosome inactivation in the germline. In the male germline of Drosophila melanogaster, a novel but poorly understood form of sex chromosome-specific transcriptional regulation occurs that is distinct from canonical sex chromosome dosage compensation or meiotic inactivation. Previous work shows that expression of reporter genes driven by testis-specific promoters is considerably lower-approximately 3-fold or more-for transgenes inserted into X chromosome versus autosome locations. Here we characterize this transcriptional suppression of X-linked genes in the male germline and its evolutionary consequences. Using transgenes and transpositions, we show that most endogenous X-linked genes, not just testis-specific ones, are transcriptionally suppressed several-fold specifically in the Drosophila male germline. In wild-type testes, this sex chromosome-wide transcriptional suppression is generally undetectable, being effectively compensated by the gene-by-gene evolutionary recruitment of strong promoters on the X chromosome. We identify and experimentally validate a promoter element sequence motif that is enriched upstream of the transcription start sites of hundreds of testis-expressed genes; evolutionarily conserved across species; associated with strong gene expression levels in testes; and overrepresented on the X chromosome. These findings show that the expression of X-linked genes in the Drosophila testes reflects a balance between chromosome-wide epigenetic transcriptional suppression and long-term compensatory adaptation by sex-linked genes. Our results have broad implications for the evolution of gene expression in the Drosophila male germline and for genome evolution.

  13. Chromosomal breakpoints characterization of two supernumerary ring chromosomes 20.

    Science.gov (United States)

    Guediche, N; Brisset, S; Benichou, J-J; Guérin, N; Mabboux, P; Maurin, M-L; Bas, C; Laroudie, M; Picone, O; Goldszmidt, D; Prévot, S; Labrune, P; Tachdjian, G

    2010-02-01

    The occurrence of an additional ring chromosome 20 is a rare chromosome abnormality, and no common phenotype has been yet described. We report on two new patients presenting with a supernumerary ring chromosome 20 both prenatally diagnosed. The first presented with intrauterine growth retardation and some craniofacial dysmorphism, and the second case had a normal phenotype except for obesity. Conventional cytogenetic studies showed for each patient a small supernumerary marker chromosome (SMC). Using fluorescence in situ hybridization, these SMCs corresponded to ring chromosomes 20 including a part of short and long arms of chromosome 20. Detailed molecular cytogenetic characterization showed different breakpoints (20p11.23 and 20q11.23 for Patient 1 and 20p11.21 and 20q11.21 for Patient 2) and sizes of the two ring chromosomes 20 (13.6 Mb for case 1 and 4.8 Mb for case 2). Review of the 13 case reports of an extra r(20) ascertained postnatally (8 cases) and prenatally (5 cases) showed varying degrees of phenotypic abnormalities. We document a detailed molecular cytogenetic chromosomal breakpoints characterization of two cases of supernumerary ring chromosomes 20. These results emphasize the need to characterize precisely chromosomal breakpoints of supernumerary ring chromosomes 20 in order to establish genotype-phenotype correlation. This report may be helpful for prediction of natural history and outcome, particularly in prenatal diagnosis.

  14. Alterations at chromosome 17 loci in peripheral nerve sheath tumors

    Energy Technology Data Exchange (ETDEWEB)

    Lothe, R.A.; Slettan, A.; Saeter, G. [Norwegian Radium Hospital, Oslo (Norway)] [and others

    1995-01-01

    Little is known about the molecular genetic changes in malignant peripheral nerve sheath tumors (MPNST). Inactivation of the TP53 gene in l7p has been reported in a few tumors. The MPNST is one of the manifestations of neurofibromatosis 1 (NF1), suggesting that the NF1 gene in 17q might be important. We present a study of 15 neurofibromas and MPNST from nine individuals. Seven patients had NF1 and six of these developed MPNST. Genetic alterations at nine polymorphic loci on chromosome 17 were examined. Allelic imbalance was detected only in the malignant tumors from NF1 patients (4/6). Complete loss of heterozygosity of 17q loci was found in three of these tumors, all including loci within the NF1 gene. Two of the malignant tumors also showed deletions on 17p. No mutations were detected within exon 5-8 of the TP53 in any of the MPNST, and none of them were TP53 protein-positive using immunostaining with mono- and polyclonal antibodies against TP53. The numbers of chromosome 17 present in each tumor were evaluated by use of fluorescence in situ hybridization (FISH) on interphase nuclei with a centromere-specific probe. A deviation from the disomic status of chromosome 17 was observed in two of the MPNST from NF1 patients. These results support the hypothesis of inactivation of both NF1 gene alleles during development of MPNST in patients with NF1. In contrast to other reports, we did not find evidence for a homozygous mutated condition of the TP53 gene in the same tumors. Finally, FISH analysis was in accordance with the DNA analysis in the deduction of the numbers of chromosome 17 in these tumors. 29 refs., 3 figs., 2 tabs.

  15. Ribosome Inactivating Proteins from Rosaceae

    Directory of Open Access Journals (Sweden)

    Chenjing Shang

    2016-08-01

    Full Text Available Ribosome-inactivating proteins (RIPs are widespread among higher plants of different taxonomic orders. In this study, we report on the RIP sequences found in the genome/transcriptome of several important Rosaceae species, including many economically important edible fruits such as apple, pear, peach, apricot, and strawberry. All RIP domains from Rosaceae share high sequence similarity with conserved residues in the catalytic site and the carbohydrate binding sites. The genomes of Malus domestica and Pyrus communis contain both type 1 and type 2 RIP sequences, whereas for Prunus mume, Prunus persica, Pyrus bretschneideri, and Pyrus communis a complex set of type 1 RIP sequences was retrieved. Heterologous expression and purification of the type 1 as well as the type 2 RIP from apple allowed to characterize the biological activity of the proteins. Both RIPs from Malus domestica can inhibit protein synthesis. Furthermore, molecular modelling suggests that RIPs from Rosaceae possess three-dimensional structures that are highly similar to the model proteins and can bind to RIP substrates. Screening of the recombinant type 2 RIP from apple on a glycan array revealed that this type 2 RIP interacts with terminal sialic acid residues. Our data suggest that the RIPs from Rosaceae are biologically active proteins.

  16. Population Dynamics of Viral Inactivation

    Science.gov (United States)

    Freeman, Krista; Li, Dong; Behrens, Manja; Streletzky, Kiril; Olsson, Ulf; Evilevitch, Alex

    We have investigated the population dynamics of viral inactivation in vitrousing time-resolved cryo electron microscopy combined with light and X-ray scattering techniques. Using bacteriophage λ as a model system for pressurized double-stranded DNA viruses, we found that virions incubated with their cell receptor eject their genome in a stochastic triggering process. The triggering of DNA ejection occurs in a non synchronized manner after the receptor addition, resulting in an exponential decay of the number of genome-filled viruses with time. We have explored the characteristic time constant of this triggering process at different temperatures, salt conditions, and packaged genome lengths. Furthermore, using the temperature dependence we determined an activation energy for DNA ejections. The dependences of the time constant and activation energy on internal DNA pressure, affected by salt conditions and encapsidated genome length, suggest that the triggering process is directly dependent on the conformational state of the encapsidated DNA. The results of this work provide insight into how the in vivo kinetics of the spread of viral infection are influenced by intra- and extra cellular environmental conditions. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1252522.

  17. Ribosome Inactivating Proteins from Rosaceae.

    Science.gov (United States)

    Shang, Chenjing; Rougé, Pierre; Van Damme, Els J M

    2016-08-22

    Ribosome-inactivating proteins (RIPs) are widespread among higher plants of different taxonomic orders. In this study, we report on the RIP sequences found in the genome/transcriptome of several important Rosaceae species, including many economically important edible fruits such as apple, pear, peach, apricot, and strawberry. All RIP domains from Rosaceae share high sequence similarity with conserved residues in the catalytic site and the carbohydrate binding sites. The genomes of Malus domestica and Pyrus communis contain both type 1 and type 2 RIP sequences, whereas for Prunus mume, Prunus persica, Pyrus bretschneideri, and Pyrus communis a complex set of type 1 RIP sequences was retrieved. Heterologous expression and purification of the type 1 as well as the type 2 RIP from apple allowed to characterize the biological activity of the proteins. Both RIPs from Malus domestica can inhibit protein synthesis. Furthermore, molecular modelling suggests that RIPs from Rosaceae possess three-dimensional structures that are highly similar to the model proteins and can bind to RIP substrates. Screening of the recombinant type 2 RIP from apple on a glycan array revealed that this type 2 RIP interacts with terminal sialic acid residues. Our data suggest that the RIPs from Rosaceae are biologically active proteins.

  18. Nondisjunction of chromosome 15: Origin and recombination

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, W.P.; Bernasconi, F.; Schinzel, A.A.; Mutirangura, A.; Ledbetter, D.H. (Baylor College of Medicine, Houston, TX (United States)); Langlois, S. (Univ. of Britisch Columbia, Vancouver (Canada)); Morris, M.A.; Malcolm, S.

    1993-09-01

    Thirty-two cases of uniparental disomy (UPD), ascertained from Prader-Willi syndrome patients (N=27) and Angelman syndrome patients (N-5), are used to investigate the pattern of recombination associated with nondisjunction of chromosome 15. In addition, the meiotic stage of nondisjunction is inferred by using markers mapping near the centromere. Two basic approaches to the analysis of recombination in specific pairwise intervals along the chromosome. This method shows a significant reduction in recombination for two of five intervals examined. Second, the observed frequency of each recombinant class (i.e., zero, one, two, three, or more observable crossovers) is compared with expected values. This is useful for testing whether the reduction in recombination can be attributed solely to a proportion of cases with no recombination at all (because of asynapsis), with the remaining groups showing normal recombination (or even excess recombination), or whether recombination is uniformly reduced. Analysis of maternal UPD(15) data shows a slight reduction in the multiple-recombinant classes, with a corresponding increase in both the zero- and one-recombinant classes over expected values. The majority, more than 82%, of the extra chromosomes in maternal UPD(15) cases are due to meiotic I nondisjunction events. In contrast, more paternal UPD(15) cases so far examined appear to have a postzygotic origin of the extra paternal chromosome. 33 refs., 1 fig., 7 tabs.

  19. Familial complex chromosomal rearrangement resulting in a recombinant chromosome.

    Science.gov (United States)

    Berend, Sue Ann; Bodamer, Olaf A F; Shapira, Stuart K; Shaffer, Lisa G; Bacino, Carlos A

    2002-05-15

    Familial complex chromosomal rearrangements (CCRs) are rare and tend to involve fewer breakpoints and fewer chromosomes than CCRs that are de novo in origin. We report on a CCR identified in a child with congenital heart disease and dysmorphic features. Initially, the child's karyotype was thought to involve a straightforward three-way translocation between chromosomes 3, 8, and 16. However, after analyzing the mother's chromosomes, the mother was found to have a more complex rearrangement that resulted in a recombinant chromosome in the child. The mother's karyotype included an inverted chromosome 2 and multiple translocations involving chromosomes 3, 5, 8, and 16. No evidence of deletion or duplication that could account for the clinical findings in the child was identified.

  20. Strong selective sweeps associated with ampliconic regions in great ape X chromosomes

    DEFF Research Database (Denmark)

    Nam, Kiwoong; Munch, Kasper; Hobolth, Asger

    2014-01-01

    The unique inheritance pattern of X chromosomes makes them preferential targets of adaptive evolution. We here investigate natural selection on the X chromosome in all species of great apes. We find that diversity is more strongly reduced around genes on the X compared with autosomes, and that a ......The unique inheritance pattern of X chromosomes makes them preferential targets of adaptive evolution. We here investigate natural selection on the X chromosome in all species of great apes. We find that diversity is more strongly reduced around genes on the X compared with autosomes...

  1. Comparative mapping of a gorilla-derived alpha satellite DNA clone on great ape and human chromosomes.

    Science.gov (United States)

    Baldini, A; Miller, D A; Shridhar, V; Rocchi, M; Miller, O J; Ward, D C

    1991-11-01

    We have isolated an alpha satellite DNA clone, pG3.9, from gorilla DNA. Fluorescence in situ hybridization on banded chromosomes under high stringency conditions revealed that pG3.9 identifies homologous sequences at the centromeric region of ten gorilla chromosomes, and, with few exceptions, also recognizes the homologous chromosomes in human. A pG3.9-like alphoid DNA is present on a larger number of orangutan chromosomes, but, in contrast, is present on only two chromosomes in the chimpanzee. These results show that the chromosomal subsets of related alpha satellite DNA sequences may undergo different patterns of evolution.

  2. De novo MECP2 duplications in two females with intellectual disability and unfavorable complete skewed X-inactivation.

    Science.gov (United States)

    Fieremans, Nathalie; Bauters, Marijke; Belet, Stefanie; Verbeeck, Jelle; Jansen, Anna C; Seneca, Sara; Roelens, Filip; De Baere, Elfride; Marynen, Peter; Froyen, Guy

    2014-11-01

    Xq28 microduplications of MECP2 are a prominent cause of a severe syndromic form of intellectual disability (ID) in males. Females are usually unaffected through near to complete X-inactivation of the aberrant X chromosome (skewing). In rare cases, affected females have been described due to random X-inactivation. Here, we report on two female patients carrying de novo MECP2 microduplications on their fully active X chromosomes. Both patients present with ID and additional clinical features. Mono-allelic expression confirmed complete skewing of X-inactivation. Consequently, significantly enhanced MECP2 mRNA levels were observed. We hypothesize that the cause for the complete skewing is due to a more harmful mutation on the other X chromosome, thereby forcing the MECP2 duplication to become active. However, we could not unequivocally identify such a second mutation by array-CGH or exome sequencing. Our data underline that, like in males, increased MECP2 dosage in females can contribute to ID too, which should be taken into account in diagnostics.

  3. Inactivation of jack bean urease by allicin.

    Science.gov (United States)

    Juszkiewicz, Adam; Zaborska, Wiesława; Sepioł, Janusz; Góra, Maciej; Zaborska, Anna

    2003-10-01

    Allicin--diallyl thiosulfinate--is the main biologically active component of freshly crushed garlic. Allicin was synthesized as described elsewhere and was tested for its inhibitory ability against jack bean urease in 20 mM phosphate buffer, pH 7.0 at 22 degrees C. The results indicate that allicin is an enzymatic inactivator. The loss of urease activity was irreversible, time- and concentration dependent and the kinetics of the inactivation was biphasic; each phase, obeyed pseudo-first-order kinetics. The rate constants for inactivation were measured for the fast and slow phases and for several concentrations of allicin. Thiol reagents, and competitive inhibitor (boric acid) protected the enzyme from loss of enzymatic activity. The studies demonstrate that urease inactivation results from the reaction between allicin and the SH-group, situated in the urease active site (Cys592).

  4. Photosensitizers mediated photodynamic inactivation against virus particles.

    Science.gov (United States)

    Sobotta, Lukasz; Skupin-Mrugalska, Paulina; Mielcarek, Jadwiga; Goslinski, Tomasz; Balzarini, Jan

    2015-01-01

    Viruses cause many diseases in humans from the rather innocent common cold to more serious or chronic, life-threatening infections. The long-term side effects, sometimes low effectiveness of standard pharmacotherapy and the emergence of drug resistance require a search for new alternative or complementary antiviral therapeutic approaches. One new approach to inactivate microorganisms is photodynamic antimicrobial chemotherapy (PACT). PACT has evolved as a potential method to inactivate viruses. The great challenge for PACT is to develop a methodology enabling the effective inactivation of viruses while leaving the host cells as untouched as possible. This review aims to provide some main directions of antiviral PACT, taking into account different photosensitizers, which have been widely investigated as potential antiviral agents. In addition, several aspects concerning PACT as a tool to assure viral inactivation in human blood products will be addressed.

  5. Major Chromosomal Rearrangements Distinguish Willow and Poplar After the Ancestral "Salicoid" Genome Duplication.

    Science.gov (United States)

    Hou, Jing; Ye, Ning; Dong, Zhongyuan; Lu, Mengzhu; Li, Laigeng; Yin, Tongming

    2016-06-27

    Populus (poplar) and Salix (willow) are sister genera in the Salicaceae family. In both lineages extant species are predominantly diploid. Genome analysis previously revealed that the two lineages originated from a common tetraploid ancestor. In this study, we conducted a syntenic comparison of the corresponding 19 chromosome members of the poplar and willow genomes. Our observations revealed that almost every chromosomal segment had a parallel paralogous segment elsewhere in the genomes, and the two lineages shared a similar syntenic pinwheel pattern for most of the chromosomes, which indicated that the two lineages diverged after the genome reorganization in the common progenitor. The pinwheel patterns showed distinct differences for two chromosome pairs in each lineage. Further analysis detected two major interchromosomal rearrangements that distinguished the karyotypes of willow and poplar. Chromosome I of willow was a conjunction of poplar chromosome XVI and the lower portion of poplar chromosome I, whereas willow chromosome XVI corresponded to the upper portion of poplar chromosome I. Scientists have suggested that Populus is evolutionarily more primitive than Salix. Therefore, we propose that, after the "salicoid" duplication event, fission and fusion of the ancestral chromosomes first give rise to the diploid progenitor of extant Populus species. During the evolutionary process, fission and fusion of poplar chromosomes I and XVI subsequently give rise to the progenitor of extant Salix species. This study contributes to an improved understanding of genome divergence after ancient genome duplication in closely related lineages of higher plants.

  6. Transfer of small chromosome fragments of Agropyron elongatum to wheat chromosome via asymmetric somatic hybridization

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    The chromosome constitution of hybrids and chromatin patterns of Agropyron elongatum(Host)Neviski in F5 somatic hybrid lines Ⅱ -1-3 and I-1-9 between Triticum aestivum L.and A.Elongatum were analyzed.Based on the statistic data of pollen mother cells,F5 I-1-9 and Ⅱ-1-3 had 20-21 bivalents with a frequency of 84.66% and 85.28%,of which,89.83% and 89.57% were ring bivalents.The result indicated that both hybrid lines were basically stable in the chromosome constitution and behavior.RAPD analysis showed that the two hybrids contained biparental and integrated DNA.GISH(Genome in situ hybridization)revealed that in the form of small chromosome segments,A.Elongatum chromatin was scattered on 4-6 wheat chromosomes near by the region of centromere and telomere in the two hybrid lines.SSR analysis indicated that A.Elongatum DNA segments were distributed on the 2A,5B,6B and 2D wheat chromosomes in the hybrids,which was in accordance with the GISH results that small-segments intercalated poly-site.

  7. Rapid chromosome evolution in recently formed polyploids in Tragopogon (Asteraceae.

    Directory of Open Access Journals (Sweden)

    K Yoong Lim

    Full Text Available BACKGROUND: Polyploidy, frequently termed "whole genome duplication", is a major force in the evolution of many eukaryotes. Indeed, most angiosperm species have undergone at least one round of polyploidy in their evolutionary history. Despite enormous progress in our understanding of many aspects of polyploidy, we essentially have no information about the role of chromosome divergence in the establishment of young polyploid populations. Here we investigate synthetic lines and natural populations of two recently and recurrently formed allotetraploids Tragopogon mirus and T. miscellus (formed within the past 80 years to assess the role of aberrant meiosis in generating chromosomal/genomic diversity. That diversity is likely important in the formation, establishment and survival of polyploid populations and species. METHODOLOGY/PRINCIPAL FINDINGS: Applications of fluorescence in situ hybridisation (FISH to natural populations of T. mirus and T. miscellus suggest that chromosomal rearrangements and other chromosomal changes are common in both allotetraploids. We detected extensive chromosomal polymorphism between individuals and populations, including (i plants monosomic and trisomic for particular chromosomes (perhaps indicating compensatory trisomy, (ii intergenomic translocations and (iii variable sizes and expression patterns of individual ribosomal DNA (rDNA loci. We even observed karyotypic variation among sibling plants. Significantly, translocations, chromosome loss, and meiotic irregularities, including quadrivalent formation, were observed in synthetic (S(0 and S(1 generations polyploid lines. Our results not only provide a mechanism for chromosomal variation in natural populations, but also indicate that chromosomal changes occur rapidly following polyploidisation. CONCLUSIONS/SIGNIFICANCE: These data shed new light on previous analyses of genome and transcriptome structures in de novo and establishing polyploid species. Crucially our

  8. Inactivation of Viruses by Benzalkonium Chloride

    Science.gov (United States)

    Armstrong, J. A.; Froelich, E. J.

    1964-01-01

    Benzalkonium chloride (as Roccal or Zephiran) was found to inactivate influenza, measles, canine distemper, rabies, fowl laryngotracheitis, vaccinia, Semliki Forest, feline pneumonitis, meningopneumonitis, and herpes simplex viruses after 10 min of exposure at 30 C or at room temperature. Poliovirus and encephalomyocarditis virus were not inactivated under the same conditions. It was concluded that all viruses tested were sensitive except members of the picorna group. The literature was reviewed. PMID:4288740

  9. Microbial Inactivation by Ultrasound Assisted Supercritical Fluids

    Science.gov (United States)

    Benedito, Jose; Ortuño, Carmen; Castillo-Zamudio, Rosa Isela; Mulet, Antonio

    A method combining supercritical carbon dioxide (SC-CO2) and high power ultrasound (HPU) has been developed and tested for microbial/enzyme inactivation purposes, at different process conditions for both liquid and solid matrices. In culture media, using only SC-CO2, the inactivation rate of E. coli and S. cerevisiae increased with pressure and temperature; and the total inactivation (7-8 log-cycles) was attained after 25 and 140 min of SC-CO2 (350 bar, 36 °C) treatment, respectively. Using SC-CO2+HPU, the time for the total inactivation of both microorganisms was reduced to only 1-2 min, at any condition selected. The SC-CO2+HPU inactivation of both microorganisms was slower in juices (avg. 4.9 min) than in culture media (avg. 1.5 min). In solid samples (chicken, turkey ham and dry-cured pork cured ham) treated with SC-CO2 and SC-CO2+HPU, the inactivation rate of E. coli increased with temperature. The application of HPU to the SC-CO2 treatments accelerated the inactivation rate of E. coli and that effect was more pronounced in treatments with isotonic solution surrounding the solid food samples. The application of HPU enhanced the SC-CO2 inactivation mechanisms of microorganisms, generating a vigorous agitation that facilitated the CO2 solubilization and the mass transfer process. The cavitation generated by HPU could damage the cell walls accelerating the extraction of vital constituents and the microbial death. Thus, using the combined technique, reasonable industrial processing times and mild process conditions could be used which could result into a cost reduction and lead to the minimization in the food nutritional and organoleptic changes.

  10. Inactivation of human myeloperoxidase by hydrogen peroxide.

    Science.gov (United States)

    Paumann-Page, Martina; Furtmüller, Paul G; Hofbauer, Stefan; Paton, Louise N; Obinger, Christian; Kettle, Anthony J

    2013-11-01

    Human myeloperoxidase (MPO) uses hydrogen peroxide generated by the oxidative burst of neutrophils to produce an array of antimicrobial oxidants. During this process MPO is irreversibly inactivated. This study focused on the unknown role of hydrogen peroxide in this process. When treated with low concentrations of H2O2 in the absence of reducing substrates, there was a rapid loss of up to 35% of its peroxidase activity. Inactivation is proposed to occur via oxidation reactions of Compound I with the prosthetic group or amino acid residues. At higher concentrations hydrogen peroxide acts as a suicide substrate with a rate constant of inactivation of 3.9 × 10(-3) s(-1). Treatment of MPO with high H2O2 concentrations resulted in complete inactivation, Compound III formation, destruction of the heme groups, release of their iron, and detachment of the small polypeptide chain of MPO. Ten of the protein's methionine residues were oxidized and the thermal stability of the protein decreased. Inactivation by high concentrations of H2O2 is proposed to occur via the generation of reactive oxidants when H2O2 reacts with Compound III. These mechanisms of inactivation may occur inside neutrophil phagosomes when reducing substrates for MPO become limiting and could be exploited when designing pharmacological inhibitors.

  11. HIGH GENETIC VARIATION IN Y CHROMOSOME PATTERNS OF THE MOCOVÍ POPULATION / Alta variación genética en los patrones del cromosoma Y de la población Mocoví

    Directory of Open Access Journals (Sweden)

    Laura Angela Glesmann

    2011-12-01

    Full Text Available In numerically small ethnic groups, the loss of genetic variability in the Y chromosome is frequent, because this genomic compartment is often subjected to selective sweeps. Despite its small size, the Mocoví population retains a significant amount of genetic variation in relation to other native communities, but their Y chromosome diversity is not known in depth. The aim of this study was to analyze the genetic variability of the Y chromosome in a sample of Mocoví males from Santa Fe province (Argentina. We genotyped 11 short tandem repeats (STRs and two single nucleotide polymorphisms (SNPs: M3 and M346. The diversity observed was high, and the 25 haplotypes obtained were compared to the YHRD database, with 13 of them absent of that database. A comparison with previous data reported from other Gran Chaco native groups showed significant differences between the Mocoví and other populations of different ethnic origin. This result and other studies on molecular markers of the Mocoví prove that this ethnic group retains a high genetic diversity that clearly differentiate them from other Amerindian populations.   Keywords: Haplotypes; genetic diversity; STRs; M3; Amerindians.   Resumen La pérdida de variabilidad genética en el cromosoma Y es frecuente en grupos étnicos reducidos numéricamente, debido a que este cromosoma suele estar sometido a barridos selectivos. A pesar de ser pequeña, la población Mocoví conserva una cantidad significativa de variación genética en relación con otras comunidades nativas, pero su diversidad a nivel del cromosoma Y no se conoce en profundidad. El objetivo de este trabajo fue analizar la variabilidad genética del cromosoma Y en una muestra de varones Mocoví de la provincia de Santa Fe (Argentina. Se tipificaron 11 microsatélites (STRs y dos marcadores bialélicos (SNPs: M3 y M346. La diversidad observada fue elevada, y los 25 haplotipos obtenidos se compararon con la base de datos YHRD, donde 13

  12. Chromosome 19 International Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Pericak-Vance, M.A. (Duke Univ., Durham, NC (United States). Medical Center); Ropers, H.H. (Univ. Hospital Nijmegen, (The Netherlands). Dept. of Human Genetics); Carrano, A.J. (Lawrence Livermore National Lab., CA (United States))

    1993-01-04

    The Second International Workshop on Human Chromosome 19 was hosted on January 25 and 26, 1992, by the Department of Human Genetics, University Hospital Nijmegen, The Netherlands, at the 'Meerdal Conference Center'. The workshop was supported by a grant from the European Community obtained through HUGO, the Dutch Research Organization (NWO) and the Muscular Dystrophy Association (MDA). Travel support for American participants was provided by the Department of Energy. The goals of this workshop were to produce genetic, physical and integrated maps of chromosome 19, to identify inconsistencies and gaps, and to discuss and exchange resources and techniques available for the completion of these maps. The second day of the meeting was largely devoted to region or disease specific efforts. In particular, the meeting served as a platform for assessing and discussing the recent progress made into the molecular elucidation of myotonic dystrophy.

  13. Kinetochore dynein generates a poleward pulling force to facilitate congression and full chromosome alignment

    Institute of Scientific and Technical Information of China (English)

    Yan Li; Wei Yu; Yun Liang; Xueliang Zhu

    2007-01-01

    For proper chromosome segregation, all kinetochores must achieve bipolar microtubule (MT) attachment and subsequently align at the spindle equator before anaphase onset. The MT minus end-directed motor dynein/dynactin binds kinetochores in prometaphase and has long been implicated in chromosome congression. Unfortunately, inactivation of dynein usually disturbs spindle organization, thus hampering evaluation of its kinetochore roles. Here we specifically eliminated kinetochore dynein/dynactin by RNAi-mediated depletion of ZW10, a protein essential for kinetochore localization of the motor. Time-lapse microscopy indicated markedly-reduced congression efficiency, though congressing chromosomes displayed similar velocities as in control cells. Moreover, cells frequently failed to achieve full chromosome alignment, despite their normal spindles. Confocal microcopy revealed that the misaligned kinetochores were monoori-ented or unattached and mostly lying outside the spindle, suggesting a difficulty to capture MTs from the opposite pole. Kinetochores on monoastral spindles were dispersed farther away from the pole and exhibited only mild oscillation. Furthermore, inactivating dynein by other means generated similar phenotypes. Therefore, kinetochore dynein produces on monooriented kinetochores a poleward pulling force, which may contribute to efficient bipolar attachment by facilitating their proper microtubule captures to promote congression as well as full chromosome alignment.

  14. Cytogenetics and chromosomes of tapeworms (Platyhelminthes, Cestoda).

    Science.gov (United States)

    Spakulová, Marta; Orosová, Martina; Mackiewicz, John S

    2011-01-01

    Tapeworms (Cestoda, Platyhelminthes) are a highly diversified group of parasites that can have significant veterinary importance as well as medical impact as disease agents of human alveococcosis, hydatidosis, taeniosis/cysticercosis/neurocysticercosis, hymenolepidosis or diphyllobothriasis. Because of their great diversity, there has been keen interest in their phylogenetic relationships to other obligate parasitic platyhelminthes, as well as within the group itself. Recent phylogenetic analyses of cestodes, however, have focused on morphological, molecular, life cycle, embryology and host-specificity features and conspicuously omitted inclusion of karyological data. Here we review the literature from 1907 to 2010 and the current status of knowledge of the chromosomes and cytogenetics within all of the cestode orders and place it within an evolutionary perspective. Karyological data are discussed and tabulated for 115 species from nine eucestode orders with ideograms of 46 species, and a comparison of cytogenetic patterns between acetabulate and bothriate cestode lineages is made. Attention is drawn to gaps in our knowledge for seven remaining orders and cestodarian groups Gyrocotylidea and Amphilinidea. Among the cytogenetic aspects covered are: chromosome number, triploidy, classical karyotype cytogenetics (banding patterns, karyotype asymmetry, secondary constrictions), as well as advanced karyotype techniques allowing location of genes on chromosomes by fluorescence in situ hybridization. We demonstrate that further progress in cestode karyosystematics rests with new molecular approaches and the application of advanced cytogenetic markers facilitating intimate karyotype analysis.

  15. Autoimmunity and Klinefelter’s syndrome: when men have two X chromosomes

    OpenAIRE

    2009-01-01

    Similar to other autoimmune diseases, systemic lupus erythematosus (SLE) predominately affects women. Recent reports demonstrate excess Klinefelter’s among men with SLE and a possible under-representation of Turner’s syndrome among women with SLE as well as a case report of a 46,XX boy with SLE. These data suggest that risk of SLE is related to a gene dose effect for the X chromosome. Such an effect could be mediated by abnormal inactivation of genes on the X chromosome as has been demonstrat...

  16. Control of bacterial chromosome replication by non-coding regions outside the origin

    DEFF Research Database (Denmark)

    Frimodt-Møller, Jakob; Charbon, Godefroid; Løbner-Olesen, Anders

    2016-01-01

    Chromosome replication in Eubacteria is initiated by initiator protein(s) binding to specific sites within the replication origin, oriC. Recently, initiator protein binding to chromosomal regions outside the origin has attracted renewed attention; as such binding sites contribute to control...... the frequency of initiations. These outside-oriC binding sites function in several different ways: by steric hindrances of replication fork assembly, by titration of initiator proteins away from the origin, by performing a chaperone-like activity for inactivation- or activation of initiator proteins...

  17. Chromosome homologies of the highly rearranged karyotypes of four Akodon species (Rodentia, Cricetidae) resolved by reciprocal chromosome painting: the evolution of the lowest diploid number in rodents.

    Science.gov (United States)

    Ventura, Karen; O'Brien, Patricia C M; Yonenaga-Yassuda, Yatiyo; Ferguson-Smith, Malcolm A

    2009-01-01

    Traditionally comparative cytogenetic studies are based mainly on banding patterns. Nevertheless, when dealing with species with highly rearranged genomes, as in Akodon species, or with other highly divergent species, cytogenetic comparisons of banding patterns prove inadequate. Hence, comparative chromosome painting has become the method of choice for genome comparisons at the cytogenetic level since it allows complete chromosome probes of a species to be hybridized in situ onto chromosomes of other species, detecting homologous genomic regions between them. In the present study, we have explored the highly rearranged complements of the Akodon species using reciprocal chromosome painting through species-specific chromosome probes obtained by chromosome sorting. The results revealed complete homology among the complements of Akodon sp. n. (ASP), 2n = 10; Akodon cursor (ACU), 2n = 15; Akodon montensis (AMO), 2n = 24; and Akodon paranaensis (APA), 2n = 44, and extensive chromosome rearrangements have been detected within the species with high precision. Robertsonian and tandem rearrangements, pericentric inversions and/or centromere repositioning, paracentric inversion, translocations, insertions, and breakpoints, where chromosomal rearrangements, seen to be favorable, were observed. Chromosome painting using the APA set of 21 autosomes plus X and Y revealed eight syntenic segments that are shared with A. montensis, A. cursor, and ASP, and one syntenic segment shared by A. montensis and A. cursor plus five exclusive chromosome associations for A. cursor and six for ASP chromosome X, except for the heterochromatin region of ASP X, and even chromosome Y shared complete homology among the species. These data indicate that all those closely related species have experienced a recent extensive process of autosomal rearrangement in which, except for ASP, there is still complete conservation of sex chromosomes homologies.

  18. Duplication and loss of chromosome 21 in two children with Down syndrome and acute leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Rogan, P.K.; Close, P.; Gannutz, L. [Pennsylvania State Univ., Hershey, PA (United States)] [and others

    1995-11-06

    Acute leukemia in Down syndrome (DS) is often associated with additional changes in the number of structure of chromosome 21. We present two DS patients whose leukemic karyotypes were associated with changes in chromosome 21 ploidy. Patient 1 developed acute lymphocytic leukemia (type L1); disomy for chromosome 21 was evident in all blast cells examined. Loss of the paternal chromosome in the leukemic clone produced maternal uniparental disomy with isodisomy over a 25-cM interval. The second patient had acute monoblastic leukemia (type M5) with tetrasomy 21 in all leukemic cells. DNA polymorphism analysis showed duplicate paternal chromosomes in the constitutional genotype. The maternal chromosome was subsequently duplicated in the leukemic clone. The distinct inheritance patterns of chromosome 21 in the blast cells of these patients would appear to indicate that leukemogenesis occurred by different genetic mechanisms in each individual. 57 refs., 2 figs., 3 tabs.

  19. American marsupials chromosomes: why study them?

    Directory of Open Access Journals (Sweden)

    Marta Svartman

    Full Text Available Marsupials, one of the three main groups of mammals, are only found in Australia and in the American continent. Studies performed in Australian marsupials have demonstrated the great potential provided by the group for the understanding of basic genetic mechanisms and chromosome evolution in mammals. Genetic studies in American marsupials are relatively scarce and cytogenetic data of most species are restricted to karyotype descriptions, usually without banding patterns. Nevertheless, the first marsupial genome sequenced was that of Monodelphis domestica, a South American species. The knowledge about mammalian genome evolution and function that resulted from studies on M. domestica is in sharp contrast with the lack of genetic data on most American marsupial species. Here, we present an overview of the chromosome studies performed in marsupials with emphasis on the South American species.

  20. American marsupials chromosomes: why study them?

    Directory of Open Access Journals (Sweden)

    Marta Svartman

    2009-01-01

    Full Text Available Marsupials, one of the three main groups of mammals, are only found in Australia and in the American continent. Studies performed in Australian marsupials have demonstrated the great potential provided by the group for the understanding of basic genetic mechanisms and chromosome evolution in mammals. Genetic studies in American marsupials are relatively scarce and cytogenetic data of most species are restricted to karyotype descriptions, usually without banding patterns. Nevertheless, the first marsupial genome sequenced was that of Monodelphis domestica, a South American species. The knowledge about mammalian genome evolution and function that resulted from studies on M. domestica is in sharp contrast with the lack of genetic data on most American marsupial species. Here, we present an overview of the chromosome studies performed in marsupials with emphasis on the South American species.

  1. Peripheral blood complete remission after splenic irradiation in Mantle-Cell Lymphoma with 11q22-23 deletion and ATM inactivation

    Directory of Open Access Journals (Sweden)

    Galliano Marco

    2006-09-01

    Full Text Available Abstract Mantle Cell Lymphoma (MCL is a well-known histological and clinical subtype of B-cell non-Hodgkin's Lymphomas. It is usually characterized by an aggressive disease course, presenting with advanced stage disease at diagnosis and with low response rates to therapy. However few cases of indolent course MCL have been described. We herein report a case of MCL with splenomegaly and peripheral blood involvement as main clinical features. The patient underwent moderate dose splenic radiation therapy and achieved spleen downsizing and peripheral blood complete remission. Splenic irradiation has been extensively used in the past as palliative treatment in several lymphoproliferative disorders and a systemic effect and sometimes peripheral blood complete remissions have been observed. Mainly advocated mechanisms responsible for this phenomenon are considered direct radiation-induced apoptotic cell death, immune modulation via proportional changes of lymphocyte subsets due to known differences in intrinsic radiosensitivity and a radiation-induced cytokine release. The peculiar intrinsic radiosensitivity pattern of lymphoid cells could probably be explained by well-defined individual genetic and molecular features. In this context, among NHLs, MCL subtype has the highest rate of ATM (Ataxia Teleangiectasia Mutated inactivation. While the ATM gene is thought to play a key-role in detecting radiation-induced DNA damage (expecially Double Strand Breaks, recent in vitro data support the hypothesis that ATM loss may actually contribute to the radiosensitivity of MCL cells. ATM status was retrospectively investigated in our patient, with the tool of Fluorescence In Situ Hybridization, showing a complete inactivation of a single ATM allele secondary to the deletion of chromosomal region 11q22-23. The presence of this kind of cytogenetic aberration may be regarded in the future as a potential predictive marker of radiation response.

  2. Asymmetry of chromosome Replichores renders the DNA translocase activity of FtsK essential for cell division and cell shape maintenance in Escherichia coli.

    Science.gov (United States)

    Lesterlin, Christian; Pages, Carine; Dubarry, Nelly; Dasgupta, Santanu; Cornet, François

    2008-12-01

    Bacterial chromosomes are organised as two replichores of opposite polarity that coincide with the replication arms from the ori to the ter region. Here, we investigated the effects of asymmetry in replichore organisation in Escherichia coli. We show that large chromosome inversions from the terminal junction of the replichores disturb the ongoing post-replicative events, resulting in inhibition of both cell division and cell elongation. This is accompanied by alterations of the segregation pattern of loci located at the inversion endpoints, particularly of the new replichore junction. None of these defects is suppressed by restoration of termination of replication opposite oriC, indicating that they are more likely due to the asymmetry of replichore polarity than to asymmetric replication. Strikingly, DNA translocation by FtsK, which processes the terminal junction of the replichores during cell division, becomes essential in inversion-carrying strains. Inactivation of the FtsK translocation activity leads to aberrant cell morphology, strongly suggesting that it controls membrane synthesis at the division septum. Our results reveal that FtsK mediates a reciprocal control between processing of the replichore polarity junction and cell division.

  3. Asymmetry of chromosome Replichores renders the DNA translocase activity of FtsK essential for cell division and cell shape maintenance in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Christian Lesterlin

    2008-12-01

    Full Text Available Bacterial chromosomes are organised as two replichores of opposite polarity that coincide with the replication arms from the ori to the ter region. Here, we investigated the effects of asymmetry in replichore organisation in Escherichia coli. We show that large chromosome inversions from the terminal junction of the replichores disturb the ongoing post-replicative events, resulting in inhibition of both cell division and cell elongation. This is accompanied by alterations of the segregation pattern of loci located at the inversion endpoints, particularly of the new replichore junction. None of these defects is suppressed by restoration of termination of replication opposite oriC, indicating that they are more likely due to the asymmetry of replichore polarity than to asymmetric replication. Strikingly, DNA translocation by FtsK, which processes the terminal junction of the replichores during cell division, becomes essential in inversion-carrying strains. Inactivation of the FtsK translocation activity leads to aberrant cell morphology, strongly suggesting that it controls membrane synthesis at the division septum. Our results reveal that FtsK mediates a reciprocal control between processing of the replichore polarity junction and cell division.

  4. The Role of Dicentric Chromosome Formation and Secondary Centromere Deletion in the Evolution of Myeloid Malignancy

    OpenAIRE

    MacKinnon, Ruth N.; Campbell, Lynda J.

    2011-01-01

    Dicentric chromosomes have been identified as instigators of the genome instability associated with cancer, but this instability is often resolved by one of a number of different secondary events. These include centromere inactivation, inversion, and intercentromeric deletion. Deletion or excision of one of the centromeres may be a significant occurrence in myeloid malignancy and other malignancies but has not previously been widely recognized, and our reports are the first describing centrom...

  5. The Role of Dicentric Chromosome Formation and Secondary Centromere Deletion in the Evolution of Myeloid Malignancy

    Directory of Open Access Journals (Sweden)

    Ruth N. MacKinnon

    2011-01-01

    Full Text Available Dicentric chromosomes have been identified as instigators of the genome instability associated with cancer, but this instability is often resolved by one of a number of different secondary events. These include centromere inactivation, inversion, and intercentromeric deletion. Deletion or excision of one of the centromeres may be a significant occurrence in myeloid malignancy and other malignancies but has not previously been widely recognized, and our reports are the first describing centromere deletion in cancer cells. We review what is known about dicentric chromosomes and the mechanisms by which they can undergo stabilization in both constitutional and cancer genomes. The failure to identify centromere deletion in cancer cells until recently can be partly explained by the standard approaches to routine diagnostic cancer genome analysis, which do not identify centromeres in the context of chromosome organization. This hitherto hidden group of primary dicentric, secondary monocentric chromosomes, together with other unrecognized dicentric chromosomes, points to a greater role for dicentric chromosomes in cancer initiation and progression than is generally acknowledged. We present a model that predicts and explains a significant role for dicentric chromosomes in the formation of unbalanced translocations in malignancy.

  6. The role of dicentric chromosome formation and secondary centromere deletion in the evolution of myeloid malignancy.

    Science.gov (United States)

    Mackinnon, Ruth N; Campbell, Lynda J

    2011-01-01

    Dicentric chromosomes have been identified as instigators of the genome instability associated with cancer, but this instability is often resolved by one of a number of different secondary events. These include centromere inactivation, inversion, and intercentromeric deletion. Deletion or excision of one of the centromeres may be a significant occurrence in myeloid malignancy and other malignancies but has not previously been widely recognized, and our reports are the first describing centromere deletion in cancer cells. We review what is known about dicentric chromosomes and the mechanisms by which they can undergo stabilization in both constitutional and cancer genomes. The failure to identify centromere deletion in cancer cells until recently can be partly explained by the standard approaches to routine diagnostic cancer genome analysis, which do not identify centromeres in the context of chromosome organization. This hitherto hidden group of primary dicentric, secondary monocentric chromosomes, together with other unrecognized dicentric chromosomes, points to a greater role for dicentric chromosomes in cancer initiation and progression than is generally acknowledged. We present a model that predicts and explains a significant role for dicentric chromosomes in the formation of unbalanced translocations in malignancy.

  7. Nanodissection of human chromosomes with near-infrared femtosecond laser pulses.

    Science.gov (United States)

    König, K; Riemann, I; Fritzsche, W

    2001-06-01

    Near-infrared laser pulses of a compact 80-MHz femtosecond laser source at 800 nm, a mean power of 15-100 mW, 170-fs pulse width, and millisecond beam dwell times at the target have been used for multiphoton-mediated nanoprocessing of human chromosomes. By focusing of the laser beam with high-numerical-aperture objectives of a scanning microscope to diffraction-limited spots and with light intensities of terawatts per cubic centimeter, precise submicrometer holes and cuts in human chromosomes have been processed by single-point exposure and line scans. A minimum FWHM cut size of ~100 nm during a partial dissection of chromosome 1, which is below the diffraction-limited spot size, and a minimum material removal of ~0.003mum (3) were determined by a scanning-force microscope. The plasma-induced ablated material corresponds to ~1/400 of the chromosome 1 volume and to ~65x10(3) base pairs of chromosomal DNA. A complete dissection could be performed with FWHM cut sizes below 200 nm. High-repetition-frequency femtosecond lasers at low mean power in combination with high-numerical-aperture focusing optics appear therefore as appropriate noncontact tools for nanoprocessing of bulk and (or) surfaces of transparent materials such as chromosomes. In particular, the noninvasive inactivation of certain genomic regions on single chromosomes within living cells becomes possible.

  8. LOSS OF HETEROZYGOSITY ON CHROMOSOME 13 IN SQUAMOUS CELL CARCINOMAS OF THE LARYNX

    Institute of Scientific and Technical Information of China (English)

    Bai Sujuan; Zhang Xue; Wang Jun; Sun Kailai; Fei Shengzhong

    1998-01-01

    Objective: To locate lost region of tumor suppressor gene on chromosome 13q in squamous cell carcinoma of the larynx (LSCC) and to provide clues and evidence for discovering and locating new suppressor gene.Methods: Loss of heterozygosity (LOH) on chromosome 13q was analyzed in 58 LSCC patients by microsatellite polymorphic sequences in loci D13S765 (13q13), RB1.20(13q14.2), D13S133 (13q14.3) and D13S318 (13q21) on chromosome 13 by PCR. Results: There weren't any LOH on chromosome 13q in 3 cases with preinvasive LSCC. Forty-five percentage (24/53) of the 53 invasive LSCC cases showed LOH at one or more loci on chromosome 13q region. The highest percentage of LOH on chromosome 13q was 52% (22/53) at D13S765locus. Conclusion: The deletion region on chromosome 13q was located near by D13S765 locus which is centromeric to RB1. In this region there is suppressor gene, which is related to the genesis and development of LSCC, possibly including RB1. The inactivation of these suppressor genes may be related to the genesis and development of invasive LSCC.

  9. Y-autosome translocation interferes with meiotic sex inactivation and expression of autosomal genes: a case study in the pig.

    Science.gov (United States)

    Barasc, H; Mary, N; Letron, R; Calgaro, A; Dudez, A M; Bonnet, N; Lahbib-Mansais, Y; Yerle, M; Ducos, A; Pinton, A

    2012-01-01

    Y-autosome translocations are rare in humans and pigs. In both species, these rearrangements can be responsible for meiotic arrest and subsequent infertility. Chromosome pairing abnormalities on the SSCX, SSCY and SSC1 chromatin domains were identified by analyzing pachytene spermatocytes from a boar carrying a (Y;1) translocation by immunolocalization of specific meiotic protein combined with FISH. Disturbance of the meiotic sex chromosome inactivation (MSCI) was observed by Cot-RNA-FISH and analysis of ZFY gene expression by sequential RNA- and DNA-FISH on spermatocytes. We hypothesized that the meiotic arrest observed in this boar might be due to the silencing of critical autosomal genes and/or the reactivation of some sex chromosome genes.

  10. Fetal calf serum heat inactivation and lipopolysaccharide contamination influence the human T lymphoblast proteome and phosphoproteome

    Directory of Open Access Journals (Sweden)

    Rahman Hazir

    2011-11-01

    Full Text Available Abstract Background The effects of fetal calf serum (FCS heat inactivation and bacterial lipopolysaccharide (LPS contamination on cell physiology have been studied, but their effect on the proteome of cultured cells has yet to be described. This study was undertaken to investigate the effects of heat inactivation of FCS and LPS contamination on the human T lymphoblast proteome. Human T lymphoblastic leukaemia (CCRF-CEM cells were grown in FCS, either non-heated, or heat inactivated, having low ( Results A total of four proteins (EIF3M, PRS7, PSB4, and SNAPA were up-regulated when CCRF-CEM cells were grown in media supplemented with heat inactivated FCS (HE as compared to cells grown in media with non-heated FCS (NHE. Six proteins (TCPD, ACTA, NACA, TCTP, ACTB, and ICLN displayed a differential phosphorylation pattern between the NHE and HE groups. Compared to the low concentration LPS group, regular levels of LPS resulted in the up-regulation of three proteins (SYBF, QCR1, and SUCB1. Conclusion The present study provides new information regarding the effect of FCS heat inactivation and change in FCS-LPS concentration on cellular protein expression, and post-translational modification in human T lymphoblasts. Both heat inactivation and LPS contamination of FCS were shown to modulate the expression and phosphorylation of proteins involved in basic cellular functions, such as protein synthesis, cytoskeleton stability, oxidative stress regulation and apoptosis. Hence, the study emphasizes the need to consider both heat inactivation and LPS contamination of FCS as factors that can influence the T lymphoblast proteome.

  11. Inactivation of enteroviruses in sewage with ozone

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, O.E.; Bogdanov, M.V.; Kazantseva, V.A.; Gabrilevskaia, L.N.; Kodkind, G.K.H.

    The study of ozone inactivation of enteroviruses in sewage showed the presence in sewage of suspensions of organic origin and bacterial flora to influence the rate of inactivation. The inactivation rate of poliomyelitis virus in sewage free from organic suspension and bacterial flora was significantly higher than that in sewage containing such suspension and bacterial flora. The inactivation rate of enteroviruses was found not to depend upon the protein and salt composition and pH of sewage or strain appurtenance of viruses. The inactivation rate of enteroviruses directly depended upon the dose of ozone and time of contact with it. Differences in the resistance of different types of poliomyelitis virus, ECHO and Coxsackie viruses to the effect of ozone are likely exist. These differences are manifested within the range of relatively small doses of ozone. E. coli is more resistant to ozone than entero-viruses. The results of laboratory studies were used to choose the regimen of sanitation of urban sewage to be used in technological cycles of industrial enterprises.

  12. Sexual differentiation in the developing mouse brain: contributions of sex chromosome genes.

    Science.gov (United States)

    Wolstenholme, J T; Rissman, E F; Bekiranov, S

    2013-03-01

    Neural sexual differentiation begins during embryogenesis and continues after birth for a variable amount of time depending on the species and brain region. Because gonadal hormones were the first factors identified in neural sexual differentiation, their role in this process has eclipsed investigation of other factors. Here, we use a mouse with a spontaneous translocation that produces four different unique sets of sex chromosomes. Each genotype has one normal X-chromosome and a unique second sex chromosome creating the following genotypes: XY(*x) , XX, XY(*) , XX(Y) (*) . This Y(*) mouse line is used by several laboratories to study two human aneuploid conditions: Turner and Klinefelter syndromes. As sex chromosome number affects behavior and brain morphology, we surveyed brain gene expression at embryonic days 11.5 and 18.5 to isolate X-chromosome dose effects in the developing brain as possible mechanistic changes underlying the phenotypes. We compared gene expression differences between gonadal males and females as well as individuals with one vs. two X-chromosomes. We present data showing, in addition to genes reported to escape X-inactivation, a number of autosomal genes are differentially expressed between the sexes and in mice with different numbers of X-chromosomes. Based on our results, we can now identify the genes present in the region around the chromosomal break point that produces the Y(*) model. Our results also indicate an interaction between gonadal development and sex chromosome number that could further elucidate the role of sex chromosome genes and hormones in the sexual differentiation of behavior.

  13. Intraspecific chromosome variability

    Directory of Open Access Journals (Sweden)

    N Dubinin

    2010-12-01

    Full Text Available (Editorial preface. The publication is presented in order to remind us of one of dramatic pages of the history of genetics. It re-opens for the contemporary reader a comprehensive work marking the priority change from plant cytogenetics to animal cytogenetics led by wide population studies which were conducted on Drosophila polytene chromosomes. The year of the publication (1937 became the point of irretrievable branching between the directions of Old World and New World genetics connected with the problems of chromosome variability and its significance for the evolution of the species. The famous book of T. Dobzhansky (1937 was published by Columbia University in the US under the title “Genetics and the origin of species”, and in the shadow of this American ‘skybuilding’ all other works grew dim. It is remarkable that both Dobzhansky and Dubinin come to similar conclusions about the role of chromosomes in speciation. This is not surprising given that they both might be considered as representatives of the Russian genetic school, by their birth and education. Interestingly, Dobzhansky had never referred to the full paper of Dubinin et al. (1937, though a previous short communication in Nature (1936 was included together with all former papers on the related subject. In full, the volume of the original publication printed in the Biological Journal in Moscow comprised 47 pages, in that number 41 pages of the Russian text accompanied by 16 Figs, a table and reference list, and, above all, 6 pages of the English summary. This final part in English is now reproduced in the authors’ version with the only addition being the reference list in the originally printed form.

  14. Chromosome assortment in Saccharum.

    Science.gov (United States)

    Al-Janabi, S M; Honeycutt, R J; Sobral, B W

    1994-12-01

    Recent work has revealed random chromosome pairing and assortment in Saccharum spontaneum L., the most widely distributed, and morphologically and cytologically variable of the species of Saccharum. This conclusion was based on the analysis of a segregating population from across between S. spontaneum 'SES 208' and a spontaneously-doubled haploid of itself, derived from anther culture. To determine whether polysomic inheritance is common in Saccharum and whether it is observed in a typical biparental cross, we studied chromosome pairing and assortment in 44 progeny of a cross between euploid, meiotically regular, 2n=80 forms of Saccharum officinarum 'LA Purple' and Saccharum robustum ' Mol 5829'. Papuan 2n=80 forms of S. robustum have been suggested as the immediate progenitor species for cultivated sugarcane (S. officinarum). A total of 738 loci in LA Purple and 720 loci in Mol 5829 were amplified and typed in the progeny by arbitrarily primed PCR using 45 primers. Fifty and 33 single-dose polymorphisms were identified in the S. officinarum and S. robustum genomes, respectively (χ 2 at 98%). Linkage analysis of single-dose polymorphisms in both genomes revealed linkages in repulsion and coupling phases. In the S. officinarum genome, a map hypothesis gave 7 linkage groups with 17 linked and 33 unlinked markers. Four of 13 pairwise linkages were in repulsion phase and 9 were in coupling phase. In the S. robustum genome, a map hypothesis gave 5 linkage groups, defined by 12 markers, with 21 markers unlinked, and 2 of 9 pairwise linkages were in repulsion phase. Therefore, complete polysomic inheritance was not observed in either species, suggesting that chromosomal behavior is different from that observed by linkage analysis of over 500 markers in the S. spontaneum map. Implications of this finding for evolution and breeding are discussed.

  15. Hormad1 mutation disrupts synaptonemal complex formation, recombination, and chromosome segregation in mammalian meiosis.

    Science.gov (United States)

    Shin, Yong-Hyun; Choi, Youngsok; Erdin, Serpil Uckac; Yatsenko, Svetlana A; Kloc, Malgorzata; Yang, Fang; Wang, P Jeremy; Meistrich, Marvin L; Rajkovic, Aleksandar

    2010-11-04

    Meiosis is unique to germ cells and essential for reproduction. During the first meiotic division, homologous chromosomes pair, recombine, and form chiasmata. The homologues connect via axial elements and numerous transverse filaments to form the synaptonemal complex. The synaptonemal complex is a critical component for chromosome pairing, segregation, and recombination. We previously identified a novel germ cell-specific HORMA domain encoding gene, Hormad1, a member of the synaptonemal complex and a mammalian counterpart to the yeast meiotic HORMA domain protein Hop1. Hormad1 is essential for mammalian gametogenesis as knockout male and female mice are infertile. Hormad1 deficient (Hormad1(-/) (-)) testes exhibit meiotic arrest in the early pachytene stage, and synaptonemal complexes cannot be visualized by electron microscopy. Hormad1 deficiency does not affect localization of other synaptonemal complex proteins, SYCP2 and SYCP3, but disrupts homologous chromosome pairing. Double stranded break formation and early recombination events are disrupted in Hormad1(-/) (-) testes and ovaries as shown by the drastic decrease in the γH2AX, DMC1, RAD51, and RPA foci. HORMAD1 co-localizes with γH2AX to the sex body during pachytene. BRCA1, ATR, and γH2AX co-localize to the sex body and participate in meiotic sex chromosome inactivation and transcriptional silencing. Hormad1 deficiency abolishes γH2AX, ATR, and BRCA1 localization to the sex chromosomes and causes transcriptional de-repression on the X chromosome. Unlike testes, Hormad1(-/) (-) ovaries have seemingly normal ovarian folliculogenesis after puberty. However, embryos generated from Hormad1(-/) (-) oocytes are hyper- and hypodiploid at the 2 cell and 8 cell stage, and they arrest at the blastocyst stage. HORMAD1 is therefore a critical component of the synaptonemal complex that affects synapsis, recombination, and meiotic sex chromosome inactivation and transcriptional silencing.

  16. Hormad1 mutation disrupts synaptonemal complex formation, recombination, and chromosome segregation in mammalian meiosis.

    Directory of Open Access Journals (Sweden)

    Yong-Hyun Shin

    2010-11-01

    Full Text Available Meiosis is unique to germ cells and essential for reproduction. During the first meiotic division, homologous chromosomes pair, recombine, and form chiasmata. The homologues connect via axial elements and numerous transverse filaments to form the synaptonemal complex. The synaptonemal complex is a critical component for chromosome pairing, segregation, and recombination. We previously identified a novel germ cell-specific HORMA domain encoding gene, Hormad1, a member of the synaptonemal complex and a mammalian counterpart to the yeast meiotic HORMA domain protein Hop1. Hormad1 is essential for mammalian gametogenesis as knockout male and female mice are infertile. Hormad1 deficient (Hormad1(-/ (- testes exhibit meiotic arrest in the early pachytene stage, and synaptonemal complexes cannot be visualized by electron microscopy. Hormad1 deficiency does not affect localization of other synaptonemal complex proteins, SYCP2 and SYCP3, but disrupts homologous chromosome pairing. Double stranded break formation and early recombination events are disrupted in Hormad1(-/ (- testes and ovaries as shown by the drastic decrease in the γH2AX, DMC1, RAD51, and RPA foci. HORMAD1 co-localizes with γH2AX to the sex body during pachytene. BRCA1, ATR, and γH2AX co-localize to the sex body and participate in meiotic sex chromosome inactivation and transcriptional silencing. Hormad1 deficiency abolishes γH2AX, ATR, and BRCA1 localization to the sex chromosomes and causes transcriptional de-repression on the X chromosome. Unlike testes, Hormad1(-/ (- ovaries have seemingly normal ovarian folliculogenesis after puberty. However, embryos generated from Hormad1(-/ (- oocytes are hyper- and hypodiploid at the 2 cell and 8 cell stage, and they arrest at the blastocyst stage. HORMAD1 is therefore a critical component of the synaptonemal complex that affects synapsis, recombination, and meiotic sex chromosome inactivation and transcriptional silencing.

  17. Chromosomal evolution in tortricid moths: conserved karyotypes with diverged features.

    Directory of Open Access Journals (Sweden)

    Jindra Síchová

    Full Text Available Moths of the family Tortricidae constitute one of the major microlepidopteran groups in terms of species richness and economic importance. Yet, despite their overall significance, our knowledge of their genome organization is very limited. In order to understand karyotype evolution in the family Tortricidae, we performed detailed cytogenetic analysis of Grapholita molesta, G. funebrana, Lobesia botrana, and Eupoecilia ambiguella, representatives of two main tortricid subfamilies, Olethreutinae and Tortricinae. Besides standard cytogenetic methods, we used fluorescence in situ hybridization for mapping of major rRNA and histone gene clusters and comparative genomic hybridization to determine the level of molecular differentiation of the W and Z sex chromosomes. Our results in combination with available data in the codling moth, Cydia pomonella, and other tortricids allow us a comprehensive reconstruction of chromosomal evolution across the family Tortricidae. The emerging picture is that the karyotype of a common ancestor of Tortricinae and Olethreutinae differentiated from the ancestral lepidopteran chromosome print of n = 31 by a sex chromosome-autosome fusion. This rearrangement resulted in a large neo-sex chromosome pair and a karyotype with n = 30 conserved in most Tortricinae species, which was further reduced to n = 28 observed in Olethreutinae. Comparison of the tortricid neo-W chromosomes showed differences in their structure and composition presumably reflecting stochasticity of molecular degeneration of the autosomal part of the neo-W chromosome. Our analysis also revealed conservative pattern of the histone distribution, which is in contrast with high rDNA mobility. Despite the dynamic evolution of rDNA, we can infer a single NOR-chromosome pair as an ancestral state not only in tortricids but probably in all Lepidoptera. The results greatly expand our knowledge of the genome architecture in tortricids, but also contribute

  18. Chromosomal evolution in tortricid moths: conserved karyotypes with diverged features.

    Science.gov (United States)

    Síchová, Jindra; Nguyen, Petr; Dalíková, Martina; Marec, František

    2013-01-01

    Moths of the family Tortricidae constitute one of the major microlepidopteran groups in terms of species richness and economic importance. Yet, despite their overall significance, our knowledge of their genome organization is very limited. In order to understand karyotype evolution in the family Tortricidae, we performed detailed cytogenetic analysis of Grapholita molesta, G. funebrana, Lobesia botrana, and Eupoecilia ambiguella, representatives of two main tortricid subfamilies, Olethreutinae and Tortricinae. Besides standard cytogenetic methods, we used fluorescence in situ hybridization for mapping of major rRNA and histone gene clusters and comparative genomic hybridization to determine the level of molecular differentiation of the W and Z sex chromosomes. Our results in combination with available data in the codling moth, Cydia pomonella, and other tortricids allow us a comprehensive reconstruction of chromosomal evolution across the family Tortricidae. The emerging picture is that the karyotype of a common ancestor of Tortricinae and Olethreutinae differentiated from the ancestral lepidopteran chromosome print of n = 31 by a sex chromosome-autosome fusion. This rearrangement resulted in a large neo-sex chromosome pair and a karyotype with n = 30 conserved in most Tortricinae species, which was further reduced to n = 28 observed in Olethreutinae. Comparison of the tortricid neo-W chromosomes showed differences in their structure and composition presumably reflecting stochasticity of molecular degeneration of the autosomal part of the neo-W chromosome. Our analysis also revealed conservative pattern of the histone distribution, which is in contrast with high rDNA mobility. Despite the dynamic evolution of rDNA, we can infer a single NOR-chromosome pair as an ancestral state not only in tortricids but probably in all Lepidoptera. The results greatly expand our knowledge of the genome architecture in tortricids, but also contribute to the

  19. Inactivation of infectious bovine rhinotracheitis virus by gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Nonomiya, Takashi; Yamashiro, Tomio; Tsutsumi, Takamasa (Animal Quarantine Service, Yokohama (Japan)); Ito, Hitoshi; Ishigaki, Isao

    1990-10-01

    Radiation inactivation of Infectious Boivne Rhinotracheitis (IBR) virus was investigated by suspending in a commercial preparation medium (c.p.m.) or IBR antibody free serum and irradiated at room temperature or dry ice frozen condition. Normal pooled serum was also analysed by electrophoresis with cellulose acetate membrane after irradiation at frozen and non-frozen condition. The virus inactivation was determined by MDBK cell line which 50 % tissue culture infectious dose (TCID{sub 50}) was calculated by Behrens Kaerber method. D{sub 10} value at non-frozen condition in serum was obtained as 1.1-1.2 kGy and that in c.p.m. was 1.3-1.4 kGy. On the other hand, D{sub 10} value was increased to 3.4-3.6 kGy in serum and 3.9 kGy in c.p.m. at frozen condition. On the irradiation effect of bovine serum, four peaks of albumin, {alpha}, {beta} and {gamma}-globulin fraction were obtained from non-irradiation and irradiated serum up to 2 kGy at non-frozen condition by electrophoresis. More than 4 kGy irradiation, the peaks of globulin fractions became not clear and at more than 8 kGy, changed to one large peak. On the other hand, these changes of electrophoretic patterns were not observed even at 30 kGy irradiation in frozen condition. From these results, necessary dose was decided as 20-25 kGy at frozen condition for inactivation of IBR virus in serum. (author).

  20. Aberrant E-cadherin staining patterns in invasive mammary carcinoma

    Directory of Open Access Journals (Sweden)

    Brogi Edi

    2005-11-01

    Full Text Available Abstract Background E-cadherin, a cell surface protein involved in cell adhesion, is present in normal breast epithelium, benign breast lesions, and in breast carcinoma. Alterations in the gene CDH1 on chromosome 16q22 are associated with changes in E-cadherin protein expression and function. Inactivation of E-cadherin in lobular carcinomas and certain diffuse gastric carcinomas may play a role in the dispersed, discohesive "single cell" growth patterns seen in these tumors. The molecular "signature" of mammary lobular carcinomas is the loss of E-cadherin protein expression as evidenced by immunohistochemistry, whereas ductal carcinomas are typically E-cadherin positive. Patients and methods We report on E-cadherin immunostaining patterns in five cases of invasive mammary carcinoma Results These were five exceptional instances in which the E-cadherin immunophenotype did not correspond to the apparent histologic classification of the lesion. These cases which are exceedingly rare in our experience are the subject of this report. Conclusion Findings such as those illustrated in this study occur in virtually all biologic phenomena and they do not invalidate the very high degree of correlation between the expression of E-cadherin and the classification of breast carcinomas as ductal or lobular type on the basis of conventional histologic criteria.

  1. Identification of Mitosis-Specific Phosphorylation in Mitotic Chromosome-Associated Proteins.

    Science.gov (United States)

    Ohta, Shinya; Kimura, Michiko; Takagi, Shunsuke; Toramoto, Iyo; Ishihama, Yasushi

    2016-09-01

    During mitosis, phosphorylation of chromosome-associated proteins is a key regulatory mechanism. Mass spectrometry has been successfully applied to determine the complete protein composition of mitotic chromosomes, but not to identify post-translational modifications. Here, we quantitatively compared the phosphoproteome of isolated mitotic chromosomes with that of chromosomes in nonsynchronized cells. We identified 4274 total phosphorylation sites and 350 mitosis-specific phosphorylation sites in mitotic chromosome-associated proteins. Significant mitosis-specific phosphorylation in centromere/kinetochore proteins was detected, although the chromosomal association of these proteins did not change throughout the cell cycle. This mitosis-specific phosphorylation might play a key role in regulation of mitosis. Further analysis revealed strong dependency of phosphorylation dynamics on kinase consensus patterns, thus linking the identified phosphorylation sites to known key mitotic kinases. Remarkably, chromosomal axial proteins such as non-SMC subunits of condensin, TopoIIα, and Kif4A, together with the chromosomal periphery protein Ki67 involved in the establishment of the mitotic chromosomal structure, demonstrated high phosphorylation during mitosis. These findings suggest a novel mechanism for regulation of chromosome restructuring in mitosis via protein phosphorylation. Our study generated a large quantitative database on protein phosphorylation in mitotic and nonmitotic chromosomes, thus providing insights into the dynamics of chromatin protein phosphorylation at mitosis onset.

  2. Chromosomal instability in near-diploid colorectal cancer: a link between numbers and structure.

    Directory of Open Access Journals (Sweden)

    Martine Muleris

    Full Text Available Chromosomal instability (CIN plays a crucial role in tumor development and occurs mainly as the consequence of either missegregation of normal chromosomes (MSG or structural rearrangement (SR. However, little is known about the respective chromosomal targets of MSG and SR and the way these processes combined within tumors to generate CIN. To address these questions, we karyotyped a consecutive series of 96 near-diploid colorectal cancers (CRCs and distinguished chromosomal changes generated by either MSG or SR in tumor cells. Eighty-three tumors (86% presented with chromosomal abnormalities that contained both MSGs and SRs to varying degrees whereas all 13 others (14% showed normal karyotype. Using a maximum likelihood statistical method, chromosomes affected by MSG or SR and likely to represent changes that are selected for during tumor progression were found to be different and mostly mutually exclusive. MSGs and SRs were not randomly associated within tumors, delineating two major pathways of chromosome alterations that consisted of either chromosome gains by MSG or chromosomal losses by both MSG and SR. CRCs showing microsatellite instability (MSI presented with either normal karyotype or chromosome gains whereas MSS (microsatellite stable CRCs exhibited a combination of the two pathways. Taken together, these data provide new insights into the respective involvement of MSG and SR in near-diploid colorectal cancers, showing how these processes target distinct portions of the genome and result in specific patterns of chromosomal changes according to MSI status.

  3. 35-Year Follow-Up of a Case of Ring Chromosome 2

    DEFF Research Database (Denmark)

    Sarri, Catherine; Douzgou, Sofia; Kontos, Haris;

    2015-01-01

    Côté et al. [1981] suggested that ring chromosomes with or without deletions share a common pattern of phenotypic anomalies, regardless of which chromosome is involved. The phenotype of this 'general ring syndrome' consists of growth failure without malformations, few or no minor anomalies, and m...

  4. Distal 5q trisomy resulting from an X;5 translocation detected by chromosome painting.

    Science.gov (United States)

    Abuelo, D N; Ahsanuddin, A N; Mark, H F

    2000-10-23

    We describe the case of a 13-year-old girl with an apparently de novo unbalanced translocation resulting in the presence of additional chromosomal material on the short arm of one X chromosome, which was detected by conventional G-banding studies. Fluorescence in situ hybridization (FISH) using the Chromoprobe Multiprobe-M protocol confirmed that the additional chromosomal material originated from chromosome 5. The karyotype of this patient is now established to be 46,X,der(X) t(X;5)(p22.3;q33), with a deletion of Xp22.3-pter and partial trisomy of 5q33-qter. The distal 5q trisomy genotype has been associated with clinical signs that include growth and mental retardation, eczema, craniofacial anomalies, and malformations of heart, lungs, abdomen, limbs, and genitalia. Our patient also has short stature, a prominent nasal bridge, a flat philtrum, a thin upper lip, dental caries, and limb and cardiac malformations, but she appears to be mildly affected compared with previously reported cases. This is the first case of distal 5q trisomy arising from a translocation with the X chromosome. Replication studies on this patient show that the derivative t(X;5) chromosome is late replicating in almost all cells examined, which indicates that this chromosome is preferentially inactivated. However, the translocated segment of chromosome 5 appears to be early replicating, which implies that the trisomic 5q segment is transcriptionally active. We cannot determine from these studies whether all or only some genes in this segment are expressed, but this patient's relatively mild clinical signs suggest that the critical region(s) that contribute to the distal 5q trisomy phenotype are at least partly suppressed. A review of other patients with X-chromosome translocations indicates that many but not all of them also have attenuated phenotypes. The mechanism of inactivation of autosomal material attached to the X chromosome is complex, with varying effects on the phenotype of the

  5. Dynamical characterization of inactivation path in voltage-gated Na(+) ion channel by non-equilibrium response spectroscopy.

    Science.gov (United States)

    Pal, Krishnendu; Gangopadhyay, Gautam

    2016-11-01

    Inactivation path of voltage gated sodium channel has been studied here under various voltage protocols as it is the main governing factor for the periodic occurrence and shape of the action potential. These voltage protocols actually serve as non-equilibrium response spectroscopic tools to study the ion channel in non-equilibrium environment. In contrast to a lot of effort in finding the crystal structure based molecular mechanism of closed-state(CSI) and open-state inactivation(OSI); here our approach is to understand the dynamical characterization of inactivation. The kinetic flux as well as energetic contribution of the closed and open- state inactivation path is compared here for voltage protocols, namely constant, pulsed and oscillating. The non-equilibrium thermodynamic quantities used in response to these voltage protocols serve as improved characterization tools for theoretical understanding which not only agrees with the previously known kinetic measurements but also predict the energetically optimum processes to sustain the auto-regulatory mechanism of action potential and the consequent inactivation steps needed. The time dependent voltage pattern governs the population of the conformational states which when couple with characteristic rate parameters, the CSI and OSI selectivity arise dynamically to control the inactivation path. Using constant, pulsed and continuous oscillating voltage protocols we have shown that during depolarization the OSI path is more favored path of inactivation however, in the hyper-polarized situation the CSI is favored. It is also shown that the re-factorisation of inactivated sodium channel to resting state occurs via CSI path. Here we have shown how the subtle energetic and entropic cost due to the change in the depolarization magnitude determines the optimum path of inactivation. It is shown that an efficient CSI and OSI dynamical profile in principle can characterize the open-state drug blocking phenomena.

  6. Genetic investigations on 8 patients affected by ring 20 chromosome syndrome

    Directory of Open Access Journals (Sweden)

    Giordano Lucio

    2010-10-01

    Full Text Available Abstract Background Mosaic Chromosome 20 ring [r(20] is a chromosomal disorder associated with a rare syndrome characterized by a typical seizure phenotype, a particular electroclinical pattern, cognitive impairment, behavioural problems and absence of a consistent pattern of dysmorphology. The pathogenic mechanism underlying seizures disorders in r(20 syndrome is still unknown. We performed a detailed clinical and genetic study on 8 patients with r(20 chromosome, aimed at detecting the genetic mechanism underlying r(20 syndrome. Methods We submitted 8 subjects with a previous diagnosis of ring 20 chromosome mosaicism to a clinical re-evaluation, followed by cytogenetic, FISH, array-CGH and molecular analyses. The genetic study was also extended to their available parents. Results FISH and array-CGH experiments indicate that cryptic deletions on chromosome 20 are not the cause of the r(20 chromosome associated disease. Moreover, no evidence of chromosome 20 uniparental disomy was found. Analysis of FISH signals given by variant in size alphoid tandem repeats probes on the normal chromosome 20 and the r(20 chromosome in the mosaic carriers suggests that the r(20 chromosome is the same chromosome not circularized in the "normal" cell line. Conclusions Higher percentages of r(20 chromosome cells were observed to be related with precocious age at seizure onset and with resistance to antiepileptic drug treatment. Behavioural problems also seem to be associated with higher percentages of r(20 chromosome cells. Our results suggest that an epigenetic mechanism perturbing the expression of genes close to the telomeric regions, rather than deletion of genes located at the distal 20p and/or 20q regions, may underlie the manifestation of r(20 syndrome.

  7. Emergence of male-biased genes on the chicken Z-chromosome: sex-chromosome contrasts between male and female heterogametic systems.

    Science.gov (United States)

    Ellegren, Hans

    2011-12-01

    There has been extensive traffic of male-biased genes out of the mammalian and Drosophila X-chromosomes, and there are also reports of an under-representation of male-biased genes on the X. This may reflect an adaptive process driven by natural selection where an autosomal location of male-biased genes is favored since male genes are only exposed to selection one-third of the time when X-linked. However, there are several alternative explanations to "out-of-the-X" gene movement, including mutational bias and a means for X-linked genes to escape meiotic sex chromosome inactivation (MSCI) during spermatogenesis. As a critical test of the hypothesis that genomic relocation of sex-biased genes is an adaptive process, I examined the emergence, and loss, of genes on the chicken Z-chromosome, i.e., a female heterogametic system (males ZZ, females ZW). Here, the analogous prediction would be an emergence of male-biased genes onto, not a loss from, the Z-chromosome because Z is found more often in males than autosomes are. I found that genes expressed in testis but not in ovary are highly over-represented among genes that have emerged on the Z-chromosome during avian evolution. Moreover, genes with male-biased expression are similarly over-represented among new Z-chromosomal genes. Interestingly, genes with female-biased expression have more often moved from than to the Z-chromosome. These observations show that male and female heterogametic organisms display opposing directionalities in the emergence and loss of sex-biased genes on sex chromosomes. This is consistent with theoretical models on the evolution of sexually antagonistic genes in which new mutations are at least partly dominant.

  8. Cohesin in determining chromosome architecture

    Energy Technology Data Exchange (ETDEWEB)

    Haering, Christian H., E-mail: christian.haering@embl.de [Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg (Germany); Jessberger, Rolf, E-mail: rolf.jessberger@tu-dresden.de [Institute of Physiological Chemistry, Dresden University of Technology, Dresden (Germany)

    2012-07-15

    Cells use ring-like structured protein complexes for various tasks in DNA dynamics. The tripartite cohesin ring is particularly suited to determine chromosome architecture, for it is large and dynamic, may acquire different forms, and is involved in several distinct nuclear processes. This review focuses on cohesin's role in structuring chromosomes during mitotic and meiotic cell divisions and during interphase.

  9. Characterization of Brca2-deficient plants excludes the role of NHEJ and SSA in the meiotic chromosomal defect phenotype.

    Directory of Open Access Journals (Sweden)

    Marilyn Dumont

    Full Text Available In somatic cells, three major pathways are involved in the repair of DNA double-strand breaks (DBS: Non-Homologous End Joining (NHEJ, Single-Strand Annealing (SSA and Homologous Recombination (HR. In somatic and meiotic HR, DNA DSB are 5' to 3' resected, producing long 3' single-stranded DNA extensions. Brca2 is essential to load the Rad51 recombinase onto these 3' overhangs. The resulting nucleofilament can thus invade a homologous DNA sequence to copy and restore the original genetic information. In Arabidopsis, the inactivation of Brca2 specifically during meiosis by an RNAi approach results in aberrant chromosome aggregates, chromosomal fragmentation and missegregation leading to a sterility phenotype. We had previously suggested that such chromosomal behaviour could be due to NHEJ. In this study, we show that knock-out plants affected in both BRCA2 genes show the same meiotic phenotype as the RNAi-inactivated plants. Moreover, it is demonstrated that during meiosis, neither NHEJ nor SSA compensate for HR deficiency in BRCA2-inactivated plants. The role of the plant-specific DNA Ligase6 is also excluded. The possible mechanism(s involved in the formation of these aberrant chromosomal bridges in the absence of HR during meiosis are discussed.

  10. Genetics Home Reference: Y chromosome infertility

    Science.gov (United States)

    ... Home Health Conditions Y chromosome infertility Y chromosome infertility Enable Javascript to view the expand/collapse boxes. ... PDF Open All Close All Description Y chromosome infertility is a condition that affects the production of ...

  11. Bacterial chromosome organization and segregation.

    Science.gov (United States)

    Badrinarayanan, Anjana; Le, Tung B K; Laub, Michael T

    2015-01-01

    If fully stretched out, a typical bacterial chromosome would be nearly 1 mm long, approximately 1,000 times the length of a cell. Not only must cells massively compact their genetic material, but they must also organize their DNA in a manner that is compatible with a range of cellular processes, including DNA replication, DNA repair, homologous recombination, and horizontal gene transfer. Recent work, driven in part by technological advances, has begun to reveal the general principles of chromosome organization in bacteria. Here, drawing on studies of many different organisms, we review the emerging picture of how bacterial chromosomes are structured at multiple length scales, highlighting the functions of various DNA-binding proteins and the impact of physical forces. Additionally, we discuss the spatial dynamics of chromosomes, particularly during their segregation to daughter cells. Although there has been tremendous progress, we also highlight gaps that remain in understanding chromosome organization and segregation.

  12. Chromosome choreography: the meiotic ballet.

    Science.gov (United States)

    Page, Scott L; Hawley, R Scott

    2003-08-08

    The separation of homologous chromosomes during meiosis in eukaryotes is the physical basis of Mendelian inheritance. The core of the meiotic process is a specialized nuclear division (meiosis I) in which homologs pair with each other, recombine, and then segregate from each other. The processes of chromosome alignment and pairing allow for homolog recognition. Reciprocal meiotic recombination ensures meiotic chromosome segregation by converting sister chromatid cohesion into mechanisms that hold homologous chromosomes together. Finally, the ability of sister kinetochores to orient to a single pole at metaphase I allows the separation of homologs to two different daughter cells. Failures to properly accomplish this elegant chromosome dance result in aneuploidy, a major cause of miscarriage and birth defects in human beings.

  13. The influence of sex chromosome aneuploidy on brain asymmetry.

    Science.gov (United States)

    Rezaie, Roozbeh; Daly, Eileen M; Cutter, William J; Murphy, Declan G M; Robertson, Dene M W; DeLisi, Lynn E; Mackay, Clare E; Barrick, Thomas R; Crow, Timothy J; Roberts, Neil

    2009-01-05

    The cognitive deficits present in individuals with sex chromosome aneuploidies suggest that hemispheric differentiation of function is determined by an X-Y homologous gene [Crow (1993); Lancet 342:594-598]. In particular, females with Turner's syndrome (TS) who have only one X-chromosome exhibit deficits of spatial ability whereas males with Klinefelter's syndrome (KS) who possess a supernumerary X-chromosome are delayed in acquiring words. Since spatial and verbal abilities are generally associated with right and left hemispheric function, such deficits may relate to anomalies of cerebral asymmetry. We therefore applied a novel image analysis technique to investigate the relationship between sex chromosome dosage and structural brain asymmetry. Specifically, we tested Crow's prediction that the magnitude of the brain torque (i.e., a combination of rightward frontal and leftward occipital asymmetry) would, as a function of sex chromosome dosage, be respectively decreased in TS women and increased in KS men, relative to genotypically normal controls. We found that brain torque was not significantly different in TS women and KS men, in comparison to controls. However, TS women exhibited significantly increased leftward brain asymmetry, restricted to the posterior of the brain and focused on the superior temporal and parietal-occipital association cortex, while KS men showed a trend for decreased brain asymmetry throughout the frontal lobes. The findings suggest that the number of sex chromosomes influences the development of brain asymmetry not simply to modify the torque but in a complex pattern along the antero-posterior axis.

  14. Sex Determination, Sex Chromosomes, and Karyotype Evolution in Insects.

    Science.gov (United States)

    Blackmon, Heath; Ross, Laura; Bachtrog, Doris

    2017-01-01

    Insects harbor a tremendous diversity of sex determining mechanisms both within and between groups. For example, in some orders such as Hymenoptera, all members are haplodiploid, whereas Diptera contain species with homomorphic as well as male and female heterogametic sex chromosome systems or paternal genome elimination. We have established a large database on karyotypes and sex chromosomes in insects, containing information on over 13000 species covering 29 orders of insects. This database constitutes a unique starting point to report phylogenetic patterns on the distribution of sex determination mechanisms, sex chromosomes, and karyotypes among insects and allows us to test general theories on the evolutionary dynamics of karyotypes, sex chromosomes, and sex determination systems in a comparative framework. Phylogenetic analysis reveals that male heterogamety is the ancestral mode of sex determination in insects, and transitions to female heterogamety are extremely rare. Many insect orders harbor species with complex sex chromosomes, and gains and losses of the sex-limited chromosome are frequent in some groups. Haplodiploidy originated several times within insects, and parthenogenesis is rare but evolves frequently. Providing a single source to electronically access data previously distributed among more than 500 articles and books will not only accelerate analyses of the assembled data, but also provide a unique resource to guide research on which taxa are likely to be informative to address specific questions, for example, for genome sequencing projects or large-scale comparative studies.

  15. Chromosomal abnormalities, meiotic behavior and fertility in domestic animals.

    Science.gov (United States)

    Villagómez, D A F; Pinton, A

    2008-01-01

    Since the advent of the surface microspreading technique for synaptonemal complex analysis, increasing interest in describing the synapsis patterns of chromosome abnormalities associated with fertility of domestic animals has been noticed during the past three decades. In spite of the number of scientific reports describing the occurrence of structural chromosome abnormalities, their meiotic behavior and gametic products, little is known in domestic animal species about the functional effects of such chromosome aberrations in the germ cell line of carriers. However, some interesting facts gained from recent and previous studies on the meiotic behavior of chromosome abnormalities of domestic animals permit us to discuss, in the frame of recent knowledge emerging from mouse and human investigations, the possible mechanism implicated in the well known association between meiotic disruption and chromosome pairing failure. New cytogenetic techniques, based on molecular and immunofluorescent analyses, are allowing a better description of meiotic processes, including gamete production. The present communication reviews the knowledge of the meiotic consequences of chromosome abnormalities in domestic animals.

  16. Schizophrenia and chromosomal deletions

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, E.A.; Baldini, A. [Baylor College of Medicine, Houston, TX (United States); Morris, M. A. [Univ. of Geneva School of Medicine, NY (United States)] [and others

    1995-06-01

    Recent genetic linkage analysis studies have suggested the presence of a schizophrenia locus on the chromosomal region 22q11-q13. Schizophrenia has also been frequently observed in patients affected with velo-cardio-facial syndrome (VCFS), a disorder frequently associated with deletions within 22q11.1. It has been hypothesized that psychosis in VCFS may be due to deletion of the catechol-o-methyl transferase gene. Prompted by these observations, we screened for 22q11 deletions in a population of 100 schizophrenics selected from the Maryland Epidemiological Sample. Our results show that there are schizophrenic patients carrying a deletion of 22q11.1 and a mild VCFS phenotype that might remain unrecognized. These findings should encourage a search for a schizophrenia-susceptibility gene within the deleted region and alert those in clinical practice to the possible presence of a mild VCFS phenotype associated with schizophrenia. 9 refs.

  17. Temperature Tolerance and Inactivation of Chikungunya Virus.

    Science.gov (United States)

    Huang, Yan-Jang S; Hsu, Wei-Wen; Higgs, Stephen; Vanlandingham, Dana L

    2015-11-01

    In late 2013, chikungunya virus (CHIKV) was introduced to the New World and large outbreaks occurred in the Caribbean islands causing over a million suspected and over 20,000 laboratory-confirmed cases. Serological analysis is an essential component for the diagnosis of CHIKV infection together with virus isolation and detection of viral nucleic acid. Demonstrating virus neutralizing by serum antibodies in a plaque reduction neutralization test (PRNT) is the gold standard of all serological diagnostic assays. Prior to the testing, heat inactivation of serum at 56°C for 30 min is required for the inactivation of complement activity and adventitious viruses. The presence of adventitious contaminating viruses may interfere with the results by leading to a higher number of plaques on the monolayers and subsequent false-negative results. This procedure is widely accepted for the inactivation of flaviviruses and alphaviruses. In this study, the thermostability of CHIKV was evaluated. Heat inactivation at 56°C for 30 min was demonstrated to be insufficient for the complete removal of infectious CHIKV virions present in the samples. This thermotolerance of CHIKV could compromise the accuracy of serum tests, and therefore longer treatment for greater than 120 min is recommended.

  18. Inactivation of Bacillus atrophaeus by OH radicals

    Science.gov (United States)

    Ono, Ryo; Yonetamari, Kenta; Tokumitsu, Yusuke; Yonemori, Seiya; Yasuda, Hachiro; Mizuno, Akira

    2016-08-01

    The inactivation of Bacillus atrophaeus by OH radicals is measured. This study aims to evaluate the bactericidal effects of OH radicals produced by atmospheric-pressure nonthermal plasma widely used for plasma medicine; however, in this study, OH radicals are produced by vacuum ultraviolet (VUV) photolysis of water vapor instead of plasma to allow the production of OH radicals with almost no other reactive species. A 172 nm VUV light from a Xe2 excimer lamp irradiates a He-H2O mixture flowing in a quartz tube to photodissociate H2O to produce OH, H, O, HO2, H2O2, and O3. The produced reactive oxygen species (ROS) flow out of the quartz tube nozzle to the bacteria on an agar plate and cause inactivation. The inactivation by OH radicals among the six ROS is observed by properly setting the experimental conditions with the help of simulations calculating the ROS densities. A 30 s treatment with approximately 0.1 ppm OH radicals causes visible inactivation.

  19. High Pressure Inactivation of HAV within Mussels

    Science.gov (United States)

    The potential of hepatitis A virus (HAV) to be inactivated within Mediterranean mussels (Mytilus galloprovincialis) and blue mussels (Mytilus edulis) by high pressure processing was evaluated. HAV was bioaccumulated within mussels to approximately 6-log10 PFU by exposure of mussels to HAV-contamina...

  20. Inactivation of prion infectivity by ionizing rays

    Science.gov (United States)

    Gominet, M.; Vadrot, C.; Austruy, G.; Darbord, J. C.

    2007-11-01

    Inactivation of prion deposits on medical devices or prion contamination in pharmaceutical raw materials is considered as impossible by using gamma irradiation. Early, the guideline WHO/CDS/CSR/APH/2000 has described irradiation as an ineffective process. But, in 2003, S. Miekka et al. noted radiation inactivation of prions in a particular application to purify human albumin, shown by the physical denaturation of the infectious protein (PrP). The aim of our study was to determine the inactivation of prions with a scrapie model (strain C506M3) by irradiating standardised preparations. Results: Gamma irradiation was partially effective, showing a 4-5 log reduction on exposure to 50 kGy. A characteristic effect-dose curve was not observed (25, 50 and 100 kGy), only an increase in the incubation period of the murine disease (229 days with 25 kGy to 290 days with 100 kGy) compared with 170 days without irradiation. Since the inactivation was not a total one, the observed effect is significant. It is proposed that further work be undertaken with the model to investigate the application of gamma radiation known levels of prion contamination.

  1. Inactivation of prion infectivity by ionizing rays

    Energy Technology Data Exchange (ETDEWEB)

    Gominet, M. [Ionisos, ZI les Chatinieres, F01120 Dagneux (France); Vadrot, C.; Austruy, G. [Paris V University, Central Pharmacy of Hospitals, 4 avenue de l' Observatoire, F-75006, Paris (France); Darbord, J.C. [Paris V University, Central Pharmacy of Hospitals, 4 avenue de l' Observatoire, F-75006, Paris (France)], E-mail: darbord@pharmacie.univ-paris5.fr

    2007-11-15

    Inactivation of prion deposits on medical devices or prion contamination in pharmaceutical raw materials is considered as impossible by using gamma irradiation. Early, the guideline WHO/CDS/CSR/APH/2000 has described irradiation as an ineffective process. But, in 2003, S. Miekka et al. noted radiation inactivation of prions in a particular application to purify human albumin, shown by the physical denaturation of the infectious protein (PrP). The aim of our study was to determine the inactivation of prions with a scrapie model (strain C506M3) by irradiating standardised preparations. Results: Gamma irradiation was partially effective, showing a 4-5 log reduction on exposure to 50 kGy. A characteristic effect-dose curve was not observed (25, 50 and 100 kGy), only an increase in the incubation period of the murine disease (229 days with 25 kGy to 290 days with 100 kGy) compared with 170 days without irradiation. Since the inactivation was not a total one, the observed effect is significant. It is proposed that further work be undertaken with the model to investigate the application of gamma radiation known levels of prion contamination.

  2. Pulsed electric field inactivation in a microreactor

    NARCIS (Netherlands)

    Fox, M.B.

    2006-01-01

    Pulsed electric fields (PEF) is a novel, non-thermal pasteurization method which uses short, high electric field pulses to inactivate microorganisms. The advantage of a pasteurization method like PEF compared to regular heat pasteurization is that the taste, flavour, texture and nutritional value ar

  3. Inactivation of Effector Caspases through Nondegradative Polyubiquitylation

    DEFF Research Database (Denmark)

    Ditzel, Mark; Broemer, Meike; Tenev, Tencho;

    2008-01-01

    Ubiquitin-mediated inactivation of caspases has long been postulated to contribute to the regulation of apoptosis. However, detailed mechanisms and functional consequences of caspase ubiquitylation have not been demonstrated. Here we show that the Drosophila Inhibitor of Apoptosis 1, DIAP1, block...

  4. [Tropical turtles chromosomes: Kinosternon leucostomum, Trachemys scripta and Staurotypus triporcatus (Testudines: Kinosternidae/Emydidae)].

    Science.gov (United States)

    Hernández-Guzmán, Javier; Indy, Jeane Rimber; Yasui, George Shigueki; Arias-Rodriguez, Lenin

    2014-06-01

    Mexico is a biodiverse country in several taxa as reptiles, that include several species of freshwater and marine turtles. Eventhough most of this group species are under protection, Tabasco State has nine native freshwater turtles, like Kinosternon leucostomum, Trachemys scripta and Staurotypus triporcatus that are very important in traditional dishes. This has resulted in a critical level of their populations, together with little biological knowledge for their conservation. Therefore, this study was dedicated to turtle cytogenetics. The study was conducted using the conventional methods for cytogenetics. The results showed the modal diploid and haploid number for K. leucostomum of 2n = 56 (2n = 56+3 microchromosomes "B") and 1n = 28 chromosomes in mitosis and meiosis, respectively. In T. scripta 2n = 50 chromosomes (2n = 50+2 microchromosomes "B") and 1n = 25 chromosomes were also characterized. Whereas in S. triporcatus we only report the 2 = 54 chromosomes (2n = 54+2 microchromosomes "B"). The karyological formula for K. leucostomum was integrated by 12 metacentric-submetacentric chromosomes "msm"/"A"+22 subtelocentric-telocentric chromosomes "stt"/"B"+22 telocentric chromosomes "T"/"C" with fundamental number (FN) of 90 chromosome arms. While T. scripta karyotype was integrated by 32 "msm/"A"+10 "stt"/"B"+8"T/"C" chromosomes, with FN of 92 arms. S. triporcatus karyotype formula was built up by 20 chromosomes "msm"/"A"+34 chromosomes "T"/"C" with FN of 74. The variation in chromosome classification, the fundamental number and the presence of supernumerary microchromosomes "B" in the studied species, were evidence of a particular chromosome cytotypes in Tabasco. We considered that the presence of microchromosomes "B" probably has different origins, and they may be very important as a pattern for the formation or separation of new species. This study also showed the absence of heterologous chromosomes between the females and males karyotypes from the studied

  5. Comparative Sex Chromosome Genomics in Snakes: Differentiation, Evolutionary Strata, and Lack of Global Dosage Compensation

    Science.gov (United States)

    Zektser, Yulia; Mahajan, Shivani; Bachtrog, Doris

    2013-01-01

    Snakes exhibit genetic sex determination, with female heterogametic sex chromosomes (ZZ males, ZW females). Extensive cytogenetic work has suggested that the level of sex chromosome heteromorphism varies among species, with Boidae having entirely homomorphic sex chromosomes, Viperidae having completely heteromorphic sex chromosomes, and Colubridae showing partial differentiation. Here, we take a genomic approach to compare sex chromosome differentiation in these three snake families. We identify homomorphic sex chromosomes in boas (Boidae), but completely heteromorphic sex chromosomes in both garter snakes (Colubridae) and pygmy rattlesnake (Viperidae). Detection of W-linked gametologs enables us to establish the presence of evolutionary strata on garter and pygmy rattlesnake sex chromosomes where recombination was abolished at different time points. Sequence analysis shows that all strata are shared between pygmy rattlesnake and garter snake, i.e., recombination was abolished between the sex chromosomes before the two lineages diverged. The sex-biased transmission of the Z and its hemizygosity in females can impact patterns of molecular evolution, and we show that rates of evolution for Z-linked genes are increased relative to their pseudoautosomal homologs, both at synonymous and amino acid sites (even after controlling for mutational biases). This demonstrates that mutation rates are male-biased in snakes (male-driven evolution), but also supports faster-Z evolution due to differential selective effects on the Z. Finally, we perform a transcriptome analysis in boa and pygmy rattlesnake to establish baseline levels of sex-biased expression in homomorphic sex chromosomes, and show that heteromorphic ZW chromosomes in rattlesnakes lack chromosome-wide dosage compensation. Our study provides the first full scale overview of the evolution of snake sex chromosomes at the genomic level, thus greatly expanding our knowledge of reptilian and vertebrate sex chromosomes

  6. Comparative sex chromosome genomics in snakes: differentiation, evolutionary strata, and lack of global dosage compensation.

    Directory of Open Access Journals (Sweden)

    Beatriz Vicoso

    Full Text Available Snakes exhibit genetic sex determination, with female heterogametic sex chromosomes (ZZ males, ZW females. Extensive cytogenetic work has suggested that the level of sex chromosome heteromorphism varies among species, with Boidae having entirely homomorphic sex chromosomes, Viperidae having completely heteromorphic sex chromosomes, and Colubridae showing partial differentiation. Here, we take a genomic approach to compare sex chromosome differentiation in these three snake families. We identify homomorphic sex chromosomes in boas (Boidae, but completely heteromorphic sex chromosomes in both garter snakes (Colubridae and pygmy rattlesnake (Viperidae. Detection of W-linked gametologs enables us to establish the presence of evolutionary strata on garter and pygmy rattlesnake sex chromosomes where recombination was abolished at different time points. Sequence analysis shows that all strata are shared between pygmy rattlesnake and garter snake, i.e., recombination was abolished between the sex chromosomes before the two lineages diverged. The sex-biased transmission of the Z and its hemizygosity in females can impact patterns of molecular evolution, and we show that rates of evolution for Z-linked genes are increased relative to their pseudoautosomal homologs, both at synonymous and amino acid sites (even after controlling for mutational biases. This demonstrates that mutation rates are male-biased in snakes (male-driven evolution, but also supports faster-Z evolution due to differential selective effects on the Z. Finally, we perform a transcriptome analysis in boa and pygmy rattlesnake to establish baseline levels of sex-biased expression in homomorphic sex chromosomes, and show that heteromorphic ZW chromosomes in rattlesnakes lack chromosome-wide dosage compensation. Our study provides the first full scale overview of the evolution of snake sex chromosomes at the genomic level, thus greatly expanding our knowledge of reptilian and vertebrate sex

  7. Cytomolecular discrimination of the A(m) chromosomes of Triticum monococcum and the A chromosomes of Triticum aestivum using microsatellite DNA repeats.

    Science.gov (United States)

    Megyeri, Mária; Mikó, Péter; Farkas, András; Molnár-Láng, Márta; Molnár, István

    2017-02-01

    The cytomolecular discrimination of the A(m)- and A-genome chromosomes facilitates the selection of wheat-Triticum monococcum introgression lines. Fluorescence in situ hybridisation (FISH) with the commonly used DNA probes Afa family, 18S rDNA and pSc119.2 showed that the more complex hybridisation pattern obtained in T. monococcum relative to bread wheat made it possible to differentiate the A(m) and A chromosomes within homoeologous groups 1, 4 and 5. In order to provide additional chromosomal landmarks to discriminate the A(m) and A chromosomes, the microsatellite repeats (GAA)n, (CAG)n, (CAC)n, (AAC)n, (AGG)n and (ACT)n were tested as FISH probes. These showed that T. monococcum chromosomes have fewer, generally weaker, simple sequence repeat (SSR) signals than the A-genome chromosomes of hexaploid wheat. A differential hybridisation pattern was observed on 6A(m) and 6A chromosomes with all the SSR probes tested except for the (ACT)n probe. The 2A(m) and 2A chromosomes were differentiated by the signals given by the (GAA)n, (CAG)n and (AAC)n repeats, while only (GAA)n discriminated the chromosomes 3A(m) and 3A. Chromosomes 7A(m) and 7A could be differentiated by the lack of (GAA)n and (AGG)n signals on 7A. As potential landmarks for identifying the A(m) chromosomes, SSR repeats will facilitate the introgression of T. monococcum chromatin into wheat.

  8. Binding of Multiple Rap1 Proteins Stimulates Chromosome Breakage Induction during DNA Replication.

    Directory of Open Access Journals (Sweden)

    Greicy H Goto

    2015-08-01

    Full Text Available Telomeres, the ends of linear eukaryotic chromosomes, have a specialized chromatin structure that provides a stable chromosomal terminus. In budding yeast Rap1 protein binds to telomeric TG repeat and negatively regulates telomere length. Here we show that binding of multiple Rap1 proteins stimulates DNA double-stranded break (DSB induction at both telomeric and non-telomeric regions. Consistent with the role of DSB induction, Rap1 stimulates nearby recombination events in a dosage-dependent manner. Rap1 recruits Rif1 and Rif2 to telomeres, but neither Rif1 nor Rif2 is required for DSB induction. Rap1-mediated DSB induction involves replication fork progression but inactivation of checkpoint kinase Mec1 does not affect DSB induction. Rap1 tethering shortens artificially elongated telomeres in parallel with telomerase inhibition, and this telomere shortening does not require homologous recombination. These results suggest that Rap1 contributes to telomere homeostasis by promoting chromosome breakage.

  9. Radiation-induced inactivation of enzymes - Molecular mechanism based on inactivation of dehydrogenases

    Science.gov (United States)

    Rodacka, Aleksandra; Gerszon, Joanna; Puchala, Mieczyslaw; Bartosz, Grzegorz

    2016-11-01

    Proteins, which have enzymatic activities play a fundamental role in the cell due to participation in most of biological processes. Oxidative-induced damage of enzymes often have marked effects on cellular processes, which in consequence determine cell functioning and survival. In this review, we focused on the radiation-induced inactivation of enzymes with particular emphasis on the inactivation of dehydrogenases. For a better understanding of this issue, the efficiency of products of water radiolysis (•OH, O2•- and H2O2) in enzyme inactivation has been analysed. Reactions of reactive oxygen species (ROS) with amino acids present in the active site of enzymes appear to have the greatest impact on enzyme inactivation.

  10. Recombination of an intrachromosomal paracentric insertion of chromosome 3

    Energy Technology Data Exchange (ETDEWEB)

    Best, R.G.; Burnett, W.J.; Brock, J.K. [Univ. of South Carolina School of Medicine, Columbia, SC (United States)] [and others

    1994-09-01

    Cytogenetic studies were initiated on a newborn female due to multiple congenital anomalies including microcephaly, clinodactyly, abnormal positioning of hands, left facial palsy, heart defect, sacral dimple, and facial dysmorphic features. Facial features were described as low set rotated ears, nystagmus, and a small, flattened nose. A structural rearrangement of the long arm of chromosome 3 was observed with a complex banding pattern. Study of parental chromosomes revealed a normal male pattern for the father, and an intrachromosomal insertion on the long arm of chromosome 3 for the mother described as 46,XX,dir ins(3)(q21q23q26.2). Further characterization of the proband`s structurally abnormal chromosome 3 revealed a karyotype best described as: 46,XX,rec(3),dupq23{r_arrow}q26.2::q21{r_arrow}q23,dir ins(3)(q21q23q26.2), which is a partial duplication of both the inserted segment as well as the intervening segment between the inserted segment and the insertion site. This would appear to be the result of a three-strand double cross-over within the insertion loop. Molecular cytogenetic studies are presently underway to further elucidate chromosome structure of the proband and her mother.

  11. Simulation of Na channel inactivation by thiazine dyes

    OpenAIRE

    1982-01-01

    Some dyes of the methylene blue family serve as artificial inactivators of the sodium channels when present inside squid axons at a concentration of approximately 0.1 mM. The dyes restore a semblance of inactivation after normal inactivation has been destroyed by pronase. In fibers that inactivate normally, the dyes hasten the decay of sodium current. Many dye-blocked channels conduct transiently on exit of the dye molecule after repolarization to the holding potential. In contrast, normally ...

  12. Cortical inactivation by cooling in small animals

    Directory of Open Access Journals (Sweden)

    Ben eCoomber

    2011-06-01

    Full Text Available Reversible inactivation of the cortex by surface cooling is a powerful method for studying the function of a particular area. Implanted cooling cryoloops have been used to study the role of individual cortical areas in auditory processing of awake-behaving cats. Cryoloops have also been used in rodents for reversible inactivation of the cortex, but recently there has been a concern that the cryoloop may also cool non-cortical structures either directly or via the perfusion of blood, cooled as it passed close to the cooling loop. In this study we have confirmed that the loop can inactivate most of the auditory cortex without causing a significant reduction in temperature of the auditory thalamus or other sub-cortical structures. We placed a cryoloop on the surface of the guinea pig cortex, cooled it to 2°C and measured thermal gradients across the neocortical surface. We found that the temperature dropped to 20-24°C among cells within a radius of about 2.5mm away from the loop. This temperature drop was sufficient to reduce activity of most cortical cells and led to the inactivation of almost the entire auditory region. When the temperature of thalamus, midbrain, and middle ear were measured directly during cortical cooling, there was a small drop in temperature (about 4°C but this was not sufficient to directly reduce neural activity. In an effort to visualise the extent of neural inactivation we measured the uptake of thallium ions following an intravenous injection. This confirmed that there was a large reduction of activity across much of the ipsilateral cortex and only a small reduction in subcortical structures.

  13. The Metalloprotease Neprilysin Degrades and Inactivates Apelin Peptides.

    Science.gov (United States)

    McKinnie, Shaun M K; Fischer, Conrad; Tran, Kelvin M H; Wang, Wang; Mosquera, Fabricio; Oudit, Gavin Y; Vederas, John C

    2016-08-17

    The apelinergic system is