Deciphering the Code of the Cancer Genome: Mechanisms of Chromosome Rearrangement

Science.gov (United States)

Willis, Nicholas A.; Rass, Emilie; Scully, Ralph

2015-01-01

Chromosome rearrangement plays a causal role in tumorigenesis by contributing to the inactivation of tumor suppressor genes, the dysregulated expression or amplification of oncogenes and the generation of novel gene fusions. Chromosome breaks are important intermediates in this process. How, when and where these breaks arise and the specific mechanisms engaged in their repair strongly influence the resulting patterns of chromosome rearrangement. Here, we review recent progress in understanding how certain distinctive features of the cancer genome, including clustered mutagenesis, tandem segmental duplications, complex breakpoints, chromothripsis, chromoplexy and chromoanasynthesis may arise. PMID:26726318

Mixed Phenotype Acute Leukemia with Two Immunophenotypically Distinct B and T Blasts Populations, Double Chromosome and Complex Karyotype: Report of an Unusual Case

Directory of Open Access Journals (Sweden)

Samah A. Kohla

2015-01-01

Full Text Available Mixed phenotype acute leukemia (MPAL is considered as a rare type of leukemia with an incidence of less than 4% of all acute leukemia based on the most recent 2008 WHO classification. Common subtypes are the B/myeloid and T/myeloid; B/T and trilineage MPAL being extremely rare. We present a case of a male in his 20s, whose peripheral blood smears showed 34% blast cells and bone marrow with 70% blasts. Immunophenotyping by multiparametric flow cytometry showed two populations of blasts, the major one with B-lineage and the minor one with T-lineage. Conventional karyotyping revealed complex karyotype with the presence of double Philadelphia chromosome ( Ph + . BCR/ABL1 rearrangement was confirmed by fluorescent in situ hybridization (FISH analysis. The BCR/ABL1 ES probe on interphase cells indicated pl90 minor m-BCR/ABL fusion in 46% and a second abnormal clone with double Ph + in 16% of the cells analyzed confirmed by reverse transcription-PCR (RT-PCR. The case was diagnosed as MPAL with double Philadelphia chromosome Ph + . The patient was treated with dasatinib, four cycle hyper CVAD/methotrexate cytarabin protocol, and allogeneic transplant. He is still alive in complete hematological, cytogenetic, and molecular remission. Mixed phenotype B/T acute leukemia is an extremely rare disease, particularly those with double Philadelphia chromosomes and clinically presents challenges in diagnosis and treatment.

Distinct roles of ATM and ATR in the regulation of ARP8 phosphorylation to prevent chromosome translocations.

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Sun, Jiying; Shi, Lin; Kinomura, Aiko; Fukuto, Atsuhiko; Horikoshi, Yasunori; Oma, Yukako; Harata, Masahiko; Ikura, Masae; Ikura, Tsuyoshi; Kanaar, Roland; Tashiro, Satoshi

2018-05-08

Chromosomal translocations are hallmarks of various types of cancers and leukemias. However, the molecular mechanisms of chromosome translocations remain largely unknown. The ataxia-telangiectasia mutated (ATM) protein, a DNA damage signaling regulator, facilitates DNA repair to prevent chromosome abnormalities. Previously, we showed that ATM deficiency led to the 11q23 chromosome translocation, the most frequent chromosome abnormalities in secondary leukemia. Here, we show that ARP8, a subunit of the INO80 chromatin remodeling complex, is phosphorylated after etoposide treatment. The etoposide-induced phosphorylation of ARP8 is regulated by ATM and ATR, and attenuates its interaction with INO80. The ATM-regulated phosphorylation of ARP8 reduces the excessive loading of INO80 and RAD51 onto the breakpoint cluster region. These findings suggest that the phosphorylation of ARP8, regulated by ATM, plays an important role in maintaining the fidelity of DNA repair to prevent the etoposide-induced 11q23 abnormalities. © 2018, Sun et al.

Influence of dose rate on the induction of simple and complex chromosome exchanges by gamma rays.

Science.gov (United States)

Loucas, Bradford D; Eberle, Richard; Bailey, Susan M; Cornforth, Michael N

2004-10-01

Single-color painting of whole chromosomes, or protocols in which only a few chromosomes are distinctively painted, will always fail to detect a proportion of complex exchanges because they frequently produce pseudosimple painting patterns that are indistinguishable from those produced by bona fide simple exchanges. When 24-color multi-fluor FISH (mFISH) was employed for the purpose of distinguishing (truly) simple from pseudosimple exchanges, it was confirmed that the acute low-LET radiation dose-response relationship for simple exchanges lacked significant upward curvature. This result has been interpreted to indicate that the formation of simple exchanges requires only one chromosome locus be damaged (e.g. broken) by radiation to initiate an exchange-not two, as classical cytogenetic theory maintains. Because a one-lesion mechanism implies single-track action, it follows that the production of simple exchanges should not be influenced by changes in dose rate. To examine this prediction, we irradiated noncycling primary human fibroblasts with graded doses of (137)Cs gamma rays at an acute dose rate of 1.10 Gy/min and compared, using mFISH, the yield of simple exchanges to that observed after exposure to the same radiation delivered at a chronic dose rate of 0.08 cGy/min. The shape of the dose response was found to be quasi-linear for both dose rates, but, counter to providing support for a one-lesion mechanism, the yield of simple aberrations was greatly reduced by protracted exposure. Although chronic doses were delivered at rates low enough to produce damage exclusively by single-track action, this did not altogether eliminate the formation of complex aberrations, an analysis of which leads to the conclusion that a single track of low-LET radiation is capable of inducing complex exchanges requiring up to four proximate breaks for their formation. For acute exposures, the ratio of simple reciprocal translocations to simple dicentrics was near unity.

Superresolution imaging reveals structurally distinct periodic patterns of chromatin along pachytene chromosomes

Science.gov (United States)

Fournier, David; Redl, Stefan; Best, Gerrit; Borsos, Máté; Tiwari, Vijay K.; Tachibana-Konwalski, Kikuë; Ketting, René F.; Parekh, Sapun H.; Cremer, Christoph; Birk, Udo J.

2015-01-01

During meiosis, homologous chromosomes associate to form the synaptonemal complex (SC), a structure essential for fertility. Information about the epigenetic features of chromatin within this structure at the level of superresolution microscopy is largely lacking. We combined single-molecule localization microscopy (SMLM) with quantitative analytical methods to describe the epigenetic landscape of meiotic chromosomes at the pachytene stage in mouse oocytes. DNA is found to be nonrandomly distributed along the length of the SC in condensed clusters. Periodic clusters of repressive chromatin [trimethylation of histone H3 at lysine (Lys) 27 (H3K27me3)] are found at 500-nm intervals along the SC, whereas one of the ends of the SC displays a large and dense cluster of centromeric histone mark [trimethylation of histone H3 at Lys 9 (H3K9me3)]. Chromatin associated with active transcription [trimethylation of histone H3 at Lys 4 (H3K4me3)] is arranged in a radial hair-like loop pattern emerging laterally from the SC. These loops seem to be punctuated with small clusters of H3K4me3 with an average spread larger than their periodicity. Our findings indicate that the nanoscale structure of the pachytene chromosomes is constrained by periodic patterns of chromatin marks, whose function in recombination and higher order genome organization is yet to be elucidated. PMID:26561583

Cloning of human basic A1, a distinct 59-kDa dystrophin-associated protein encoded on chromosome 8q23-24

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Ahn, A.H. [Harvard Medical School, Boston, MA (United States); Yoshida, Mikiharu; Hagiwara, Yasuko; Ozawa, Eijiro [National Institute of Neuroscience, Ogawa Higashi, Kodaira (Japan); Anderson, M.S.; Feener, C.A.; Selig, S. [Howard Hughes Medical Institute at Children`s Hospital, Boston, MA (United States); Kunkel, L.M. [Harvard Medical School, Boston, MA (United States)]|[Howard Hughes Medical Institute at Children`s Hosptial, Boston, MA (United States)

1994-05-10

Duchenne and Becker muscular dystrophies are caused by defects of dystrophin, which forms a part of the membrane cytoskeleton of specialized cells such as muscle. It has been previously shown that the dystrophin-associated protein A1 (59-kDa DAP) is actually a heterogeneous group of phosphorylated proteins consisting of an acidic ({alpha}-A1) and a distinct basic ({beta}-A1) component. Partial peptide sequence of the A1 complex purified from rabbit muscle permitted the design of oligonucleotide probes that were used to isolate a cDNA for one human isoform of A1. This cDNA encodes a basic A1 isoform that is distinct from the recently described syntrophins in Torpedo and mouse and is expressed in many tissues with at least five distinct mRNA species of 5.9, 4.8, 4.3, 3.1, and 1.5 kb. A comparison of the human cDNA sequence with the GenBank expressed sequence tag (EST) data base has identified a relative from human skeletal muscle, EST25263, which is probably a human homologue of the published mouse syntrophin 2. The authors have mapped the human basic component of A1 and EST25263 genes to chromosomes 8q23-24 and 16, respectively.

Chromosomal Replication Complexity: A Novel DNA Metrics and Genome Instability Factor.

Directory of Open Access Journals (Sweden)

Andrei Kuzminov

2016-10-01

Full Text Available As the ratio of the copy number of the most replicated to the unreplicated regions in the same chromosome, the definition of chromosomal replication complexity (CRC appears to leave little room for variation, being either two during S-phase or one otherwise. However, bacteria dividing faster than they replicate their chromosome spike CRC to four and even eight. A recent experimental inquiry about the limits of CRC in Escherichia coli revealed two major reasons to avoid elevating it further: (i increased chromosomal fragmentation and (ii complications with subsequent double-strand break repair. Remarkably, examples of stable elevated CRC in eukaryotic chromosomes are well known under various terms like "differential replication," "underreplication," "DNA puffs," "onion-skin replication," or "re-replication" and highlight the phenomenon of static replication fork (sRF. To accurately describe the resulting "amplification by overinitiation," I propose a new term: "replification" (subchromosomal overreplication. In both prokaryotes and eukaryotes, replification, via sRF processing, causes double-strand DNA breaks and, with their repair elevating chromosomal rearrangements, represents a novel genome instability factor. I suggest how static replication bubbles could be stabilized and speculate that some tandem duplications represent such persistent static bubbles. Moreover, I propose how static replication bubbles could be transformed into tandem duplications, double minutes, or inverted triplications. Possible experimental tests of these models are discussed.

A role for Aurora C in the chromosomal passenger complex during human preimplantation embryo development

NARCIS (Netherlands)

Santos, Margarida Avo; van de Werken, Christine; de Vries, Marieke; Jahr, Holger; Vromans, Martijn J. M.; Laven, Joop S. E.; Fauser, Bart C.; Kops, Geert J.; Lens, Susanne M.; Baart, Esther B.

BACKGROUND: Human embryos generated by IVF demonstrate a high incidence of chromosomal segregation errors during the cleavage divisions. To analyse underlying molecular mechanisms, we investigated the behaviour of the chromosomal passenger complex (CPC) in human oocytes and embryos. This important

Resolving complex chromosome structures during meiosis: versatile deployment of Smc5/6

NARCIS (Netherlands)

Verver, Dideke E.; Hwang, Grace H.; Jordan, Philip W.; Hamer, Geert

2016-01-01

The Smc5/6 complex, along with cohesin and condensin, is a member of the structural maintenance of chromosome (SMC) family, large ring-like protein complexes that are essential for chromatin structure and function. Thanks to numerous studies of the mitotic cell cycle, Smc5/6 has been implicated to

Resolving complex chromosome structures during meiosis: versatile deployment of Smc5/6.

Science.gov (United States)

Verver, Dideke E; Hwang, Grace H; Jordan, Philip W; Hamer, Geert

2016-03-01

The Smc5/6 complex, along with cohesin and condensin, is a member of the structural maintenance of chromosome (SMC) family, large ring-like protein complexes that are essential for chromatin structure and function. Thanks to numerous studies of the mitotic cell cycle, Smc5/6 has been implicated to have roles in homologous recombination, restart of stalled replication forks, maintenance of ribosomal DNA (rDNA) and heterochromatin, telomerase-independent telomere elongation, and regulation of chromosome topology. The nature of these functions implies that the Smc5/6 complex also contributes to the profound chromatin changes, including meiotic recombination, that characterize meiosis. Only recently, studies in diverse model organisms have focused on the potential meiotic roles of the Smc5/6 complex. Indeed, Smc5/6 appears to be essential for meiotic recombination. However, due to both the complexity of the process of meiosis and the versatility of the Smc5/6 complex, many additional meiotic functions have been described. In this review, we provide a clear overview of the multiple functions found so far for the Smc5/6 complex in meiosis. Additionally, we compare these meiotic functions with the known mitotic functions in an attempt to find a common denominator and thereby create clarity in the field of Smc5/6 research.

Chromosome segregation regulation in human zygotes : Altered mitotic histone phosphorylation dynamics underlying centromeric targeting of the chromosomal passenger complex

NARCIS (Netherlands)

Van De Werken, C.; Avo Santos, M.; Laven, J. S E; Eleveld, C.; Fauser, B. C J M; Lens, S. M A; Baart, E. B.

2015-01-01

STUDY QUESTION Are the kinase feedback loops that regulate activation and centromeric targeting of the chromosomal passenger complex (CPC), functional during mitosis in human embryos? SUMMARY ANSWER Investigation of the regulatory kinase pathways involved in centromeric CPC targeting revealed normal

Partial 2p deletion in a girl with a complex chromosome rearrangement involving chromosomes 2, 6, 11, and 21.

OpenAIRE

Young, R S; Medrano, M A; Hansen, K L

1985-01-01

We describe the clinical and cytogenetic findings of a 9 1/2 month old girl with a complex chromosome rearrangement resulting in a probable deletion of band 2p14. She does not resemble other reported cases of del(2p).

Chromosomes as well as chromosomal subdomains constitute distinct units in interphase nuclei

NARCIS (Netherlands)

Visser, A. E.; Aten, J. A.

1999-01-01

Fluorescence in situ hybridization has demonstrated that chromosomes form individual territories in interphase nuclei. However, this technique is not suitable to determine whether territories are mutually exclusive or interwoven. This notion, however, is essential for understanding functional

Centralspindlin and Chromosomal Passenger Complex Behavior During Normal and Rappaport Furrow Specification in Echinoderm Embryos

Science.gov (United States)

Argiros, Haroula; Henson, Lauren; Holguin, Christiana; Foe, Victoria; Shuster, Charles Bradley

2014-01-01

The chromosomal passenger (CPC) and Centralspindlin complexes are essential for organizing the anaphase central spindle and providing cues that position the cytokinetic furrow between daughter nuclei. However, echinoderm zygotes are also capable of forming “Rappaport furrows” between asters positioned back-to-back without intervening chromosomes. To understand how these complexes contribute to normal and Rappaport furrow formation, we studied the localization patterns of Survivin and mitotic-kinesin-like-protein1 (MKLP1), members respectively of the CPC and the Centralspindlin complex, and the effect of CPC inhibition on cleavage in mono- and binucleate echinoderm zygotes. In zygotes, Survivin initially localized to metaphase chromosomes, upon anaphase onset relocalized to the central spindle and then, together with MKLP1 spread towards the equatorial cortex in an Aurora-dependent manner. Inhibition of Aurora kinase activity resulted in disruption of central spindle organization and furrow regression, although astral microtubule elongation and furrow initiation were normal. In binucleate cells containing two parallel spindles MKLP1 and Survivin localized to the plane of the former metaphase plate, but were not observed in the secondary cleavage plane formed between unrelated spindle poles, except when chromosomes were abnormally present there. However, the secondary furrow was sensitive to Aurora inhibition, indicating that Aurora kinase may still contribute to furrow ingression without chromosomes nearby. Our results provide insights that reconcile classic micromanipulation studies with current molecular understanding of furrow specification in animal cells. PMID:22887753

Tyrosine kinase chromosomal translocations mediate distinct and overlapping gene regulation events

International Nuclear Information System (INIS)

Kim, Hani; Gillis, Lisa C; Jarvis, Jordan D; Yang, Stuart; Huang, Kai; Der, Sandy; Barber, Dwayne L

2011-01-01

Leukemia is a heterogeneous disease commonly associated with recurrent chromosomal translocations that involve tyrosine kinases including BCR-ABL, TEL-PDGFRB and TEL-JAK2. Most studies on the activated tyrosine kinases have focused on proximal signaling events, but little is known about gene transcription regulated by these fusions. Oligonucleotide microarray was performed to compare mRNA changes attributable to BCR-ABL, TEL-PDGFRB and TEL-JAK2 after 1 week of activation of each fusion in Ba/F3 cell lines. Imatinib was used to control the activation of BCR-ABL and TEL-PDGFRB, and TEL-JAK2-mediated gene expression was examined 1 week after Ba/F3-TEL-JAK2 cells were switched to factor-independent conditions. Microarray analysis revealed between 800 to 2000 genes induced or suppressed by two-fold or greater by each tyrosine kinase, with a subset of these genes commonly induced or suppressed among the three fusions. Validation by Quantitative PCR confirmed that eight genes (Dok2, Mrvi1, Isg20, Id1, gp49b, Cxcl10, Scinderin, and collagen Vα1(Col5a1)) displayed an overlapping regulation among the three tested fusion proteins. Stat1 and Gbp1 were induced uniquely by TEL-PDGFRB. Our results suggest that BCR-ABL, TEL-PDGFRB and TEL-JAK2 regulate distinct and overlapping gene transcription profiles. Many of the genes identified are known to be involved in processes associated with leukemogenesis, including cell migration, proliferation and differentiation. This study offers the basis for further work that could lead to an understanding of the specificity of diseases caused by these three chromosomal translocations

Hyperacetylation and differential deacetylation of histones H4 and H3 define two distinct classes of acetylated SV40 chromosomes early in infection

International Nuclear Information System (INIS)

Milavetz, Barry

2004-01-01

SV40 chromosomes undergoing encapsidation late in infection and SV40 chromatin in virions are hyperacetylated on histones H4 and H3. However, the fate of the SV40 chromosomes containing hyperacetylated histones in a subsequent round of infection has not been determined. In order to determine if SV40 chromosomes undergo changes in the extent of histone acetylation during early infection, we have analyzed SV40 chromosomes isolated 30 min and 3 h postinfection by quantitative ChIP assays, depletion ChIP assays, competitive ChIP assays, and ChIP assays combined with restriction endonuclease sensitivity using antibodies to hyperacetylated histones H4 and H3. We have shown that at 30 min postinfection, the hyperacetylated histones are associated with two distinct classes of SV40 chromosomes. One form is hyperacetylated specifically on histone H4 while a second form is hyperacetylated on both H4 and H3. Both forms of chromosomes appear to contain a nucleosome-free promoter region. Over the course of the next few hours of infection, the class of SV40 chromosomes hyperacetylated on only H4 is reduced or completely eliminated through deacetylation

Sensitive detection of chromosomal segments of distinct ancestry in admixed populations.

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Alkes L Price

2009-06-01

Full Text Available Identifying the ancestry of chromosomal segments of distinct ancestry has a wide range of applications from disease mapping to learning about history. Most methods require the use of unlinked markers; but, using all markers from genome-wide scanning arrays, it should in principle be possible to infer the ancestry of even very small segments with exquisite accuracy. We describe a method, HAPMIX, which employs an explicit population genetic model to perform such local ancestry inference based on fine-scale variation data. We show that HAPMIX outperforms other methods, and we explore its utility for inferring ancestry, learning about ancestral populations, and inferring dates of admixture. We validate the method empirically by applying it to populations that have experienced recent and ancient admixture: 935 African Americans from the United States and 29 Mozabites from North Africa. HAPMIX will be of particular utility for mapping disease genes in recently admixed populations, as its accurate estimates of local ancestry permit admixture and case-control association signals to be combined, enabling more powerful tests of association than with either signal alone.

Detection of expression quantitative trait Loci in complex mouse crosses: impact and alleviation of data quality and complex population substructure.

Science.gov (United States)

Iancu, Ovidiu D; Darakjian, Priscila; Kawane, Sunita; Bottomly, Daniel; Hitzemann, Robert; McWeeney, Shannon

2012-01-01

Complex Mus musculus crosses, e.g., heterogeneous stock (HS), provide increased resolution for quantitative trait loci detection. However, increased genetic complexity challenges detection methods, with discordant results due to low data quality or complex genetic architecture. We quantified the impact of theses factors across three mouse crosses and two different detection methods, identifying procedures that greatly improve detection quality. Importantly, HS populations have complex genetic architectures not fully captured by the whole genome kinship matrix, calling for incorporating chromosome specific relatedness information. We analyze three increasingly complex crosses, using gene expression levels as quantitative traits. The three crosses were an F(2) intercross, a HS formed by crossing four inbred strains (HS4), and a HS (HS-CC) derived from the eight lines found in the collaborative cross. Brain (striatum) gene expression and genotype data were obtained using the Illumina platform. We found large disparities between methods, with concordance varying as genetic complexity increased; this problem was more acute for probes with distant regulatory elements (trans). A suite of data filtering steps resulted in substantial increases in reproducibility. Genetic relatedness between samples generated overabundance of detected eQTLs; an adjustment procedure that includes the kinship matrix attenuates this problem. However, we find that relatedness between individuals is not evenly distributed across the genome; information from distinct chromosomes results in relatedness structure different from the whole genome kinship matrix. Shared polymorphisms from distinct chromosomes collectively affect expression levels, confounding eQTL detection. We suggest that considering chromosome specific relatedness can result in improved eQTL detection.

Analysis of complex-type chromosome exchanges in astronauts' lymphocytes after space flight as a biomarker of high-LET exposure

International Nuclear Information System (INIS)

George, K.; Wu, H.; Willingham, V.; Cucinotta, F.A.

2002-01-01

High-linear energy transfer (LET) radiation is moreefficient in producing complex-type chromosome exchanges than sparsely ionizing radiation, and this can potentially be used as a biomarker of radiation quality. To investigate if complex chromosome exchanges are induced by the high-LET component of space radiation exposure, damage was assessed in astronauts' blood lymphocytes before and after longduration missions of 3-4 months. The frequency of simple translocations increased significantly for most of the crewmembers studied. However, there were few complex exchanges detected and only one crewmember had a significant increase after flight. It has been suggested that the yield of complex chromosome damage could be underestimated when analyzing metaphase cellscollected at one time point after irradiation, andanalysis of chemically-induced premature chromosomecondensation (PCC) may be more accurate since problems with complicated cell-cycle delays are avoided.However, in this case the yields of chromosome damage were similar for metaphase and PCC analysis of astronauts' lymphocytes. It appears that the use of complex-type exchanges as biomarkerof radiation quality in vivo after low-dose chronicexposure in mixed radiation fields is hampered by statistical uncertainties. (author)

The X chromosome in space.

Science.gov (United States)

Jégu, Teddy; Aeby, Eric; Lee, Jeannie T

2017-06-01

Extensive 3D folding is required to package a genome into the tiny nuclear space, and this packaging must be compatible with proper gene expression. Thus, in the well-hierarchized nucleus, chromosomes occupy discrete territories and adopt specific 3D organizational structures that facilitate interactions between regulatory elements for gene expression. The mammalian X chromosome exemplifies this structure-function relationship. Recent studies have shown that, upon X-chromosome inactivation, active and inactive X chromosomes localize to different subnuclear positions and adopt distinct chromosomal architectures that reflect their activity states. Here, we review the roles of long non-coding RNAs, chromosomal organizational structures and the subnuclear localization of chromosomes as they relate to X-linked gene expression.

Chromosome segregation regulation in human zygotes: altered mitotic histone phosphorylation dynamics underlying centromeric targeting of the chromosomal passenger complex.

Science.gov (United States)

van de Werken, C; Avo Santos, M; Laven, J S E; Eleveld, C; Fauser, B C J M; Lens, S M A; Baart, E B

2015-10-01

Are the kinase feedback loops that regulate activation and centromeric targeting of the chromosomal passenger complex (CPC), functional during mitosis in human embryos? Investigation of the regulatory kinase pathways involved in centromeric CPC targeting revealed normal phosphorylation dynamics of histone H2A at T120 (H2ApT120) by Bub1 kinase and subsequent recruitment of Shugoshin, but phosphorylation of histone H3 at threonine 3 (H3pT3) by Haspin failed to show the expected centromeric enrichment on metaphase chromosomes in the zygote. Human cleavage stage embryos show high levels of chromosomal instability. What causes this high error rate is unknown, as mechanisms used to ensure proper chromosome segregation in mammalian embryos are poorly described. In this study, we investigated the pathways regulating CPC targeting to the inner centromere in human embryos. We characterized the distribution of the CPC in relation to activity of its two main centromeric targeting pathways: the Bub1-H2ApT120-Sgo-CPC and Haspin-H3pT3-CPC pathways. The study was conducted between May 2012 and March 2014 on human surplus embryos resulting from in vitro fertilization treatment and donated for research. In zygotes, nuclear envelope breakdown was monitored by time-lapse imaging to allow timed incubations with specific inhibitors to arrest at prometaphase and metaphase, and to interfere with Haspin and Aurora B/C kinase activity. Functionality of the targeting pathways was assessed through characterization of histone phosphorylation dynamics by immunofluorescent analysis, combined with gene expression by RT-qPCR and immunofluorescent localization of key pathway proteins. Immunofluorescent analysis of the CPC subunit Inner Centromere Protein revealed the pool of stably bound CPC proteins was not strictly confined to the inner centromere of prometaphase chromosomes in human zygotes, as observed in later stages of preimplantation development and somatic cells. Investigation of the

Complex distal 10q rearrangement in a girl with mild intellectual disability: follow up of the patient and review of the literature of non-acrocentric satellited chromosomes.

Science.gov (United States)

Sarri, Catherine; Douzgou, Sofia; Gyftodimou, Yolanda; Tümer, Zeynep; Ravn, Kirstine; Pasparaki, Angela; Sarafidou, Theologia; Kontos, Harry; Kokotas, Haris; Karadima, Georgia; Grigoriadou, Maria; Pandelia, Effie; Theodorou, Virginia; Moschonas, Nicholas K; Petersen, Michael B

2011-11-01

We report on an intellectually disabled girl with a de novo satellited chromosome 10 (10qs) and performed a review of the literature of the non-acrocentric satellited chromosomes (NASC). Satellites and stalks normally occur on the short arms of acrocentric chromosomes; however, the literature cites several reports of satellited non-acrocentric chromosomes, which presumably result from a translocation with an acrocentric chromosome. This is, to our knowledge, the third report of a 10qs chromosome. The phenotype observed in the proband prompted a search for a structural rearrangement of chromosome 10q. By microsatellite analysis we observed a 4 Mb deletion on the long arm of chromosome 10, approximately 145 kb from the telomere. FISH and array CGH analyses revealed a complex rearrangement involving in range from the centromere to the telomere: A 9.64 Mb 10q26.11-q26.2 duplication, a 1.3 Mb region with no copy number change, followed by a 5.62 Mb 10q26.2-q26.3 deletion and a translocation of satellite material. The homology between the repeat sequences at 10q subtelomere region and the sequences on the acrocentric short arms may explain the origin of the rearrangement and it is likely that the submicroscopic microdeletion and microduplication are responsible for the abnormal phenotype in our patient. The patient presented here, with a 15-year follow-up, manifests a distinct phenotype different from the 10q26 pure distal monosomy and trisomy syndromes. Copyright © 2011 Wiley Periodicals, Inc.

Analysis of chromosome rearrangements on the basis of synaptonemal complexes in the offspring of mice exposed to γ-rays

International Nuclear Information System (INIS)

Kalikinskaya, E.I.; Bogdanov, Yu.F.; Kolomiets, O.L.; Shevchenko, V.A.

1986-01-01

Electron-microscopic analysis of synaptonemic complexes (SC), spread on the hypophase surface, was conducted to investigate chromosome rearrangements in sterile and semisterile F 1 malemause offsprings, exposed to 5 Gy γ-rays Paralelly Chromosome rearrangement account in diakinesis-metaphase 1 was conducted using light microscope, in the same animals. During SC analysis in pachytene chromosome rearrangements were found in 63% of spermatocytes. Under chromosome analysis in diakinesis-metaphase 1 in the same animals chromosome rearrangements were found only in 32% of cells. SC analysis allows one to reveal chromosome rearrangements, which can not be revealed in diakinesis-metaphase 1

Cytological maps of lampbrush chromosomes of European water frogs (Pelophylax esculentus complex) from the Eastern Ukraine

Science.gov (United States)

2013-01-01

Background Hybridogenesis (hemiclonal inheritance) is a kind of clonal reproduction in which hybrids between parental species are reproduced by crossing with one of the parental species. European water frogs (Pelophylax esculentus complex) represent an appropriate model for studying interspecies hybridization, processes of hemiclonal inheritance and polyploidization. P. esculentus complex consists of two parental species, P. ridibundus (the lake frog) and P. lessonae (the pool frog), and their hybridogenetic hybrid – P. esculentus (the edible frog). Parental and hybrid frogs can reproduce syntopically and form hemiclonal population systems. For studying mechanisms underlying the maintenance of water frog population systems it is required to characterize the karyotypes transmitted in gametes of parental and different hybrid animals of both sexes. Results In order to obtain an instrument for characterization of oocyte karyotypes in hybrid female frogs, we constructed cytological maps of lampbrush chromosomes from oocytes of both parental species originating in Eastern Ukraine. We further identified certain molecular components of chromosomal marker structures and mapped coilin-rich spheres and granules, chromosome associated nucleoli and special loops accumulating splicing factors. We recorded the dissimilarities between P. ridibundus and P. lessonae lampbrush chromosomes in the length of orthologous chromosomes, number and location of marker structures and interstitial (TTAGGG)n-repeat sites as well as activity of nucleolus organizer. Satellite repeat RrS1 was mapped in centromere regions of lampbrush chromosomes of the both species. Additionally, we discovered transcripts of RrS1 repeat in oocytes of P. ridibundus and P. lessonae. Moreover, G-rich transcripts of telomere repeat were revealed in association with terminal regions of P. ridibundus and P. lessonae lampbrush chromosomes. Conclusions The constructed cytological maps of lampbrush chromosomes of P

Isolation of a cosmid sublibrary for a region of chromosome 12 frequently amplified in human cancers using a complex chromosome microdissection probe

Energy Technology Data Exchange (ETDEWEB)

Elkahloun, A.G.; Meltzer, P.S.; Guan, Xin-Yuan [National Institutes of Health, Bethesda, MD (United States)] [and others

1996-02-01

Chromosome-specific cosmid libraries are in extremely useful resource for positional cloning projects. Once a particular region of interest has been identified, it would be of value to have an approach for isolating chromosome band-specific cosmids that could be assembled into a sublibrary for rapid screening. We constructed a region-specific sublibrary of 700 cosmids by screening a chromosome 12-specific cosmid library with a complex probe generated by degenerate oligonucleotide-primed PCR of a microdissected homogeneously staining region containing sequences amplified from chromosome 12q13-q15. Based on fluorescence in situ hybridization, approximately 60% of the cosmids in the sublibrary were derived from the microdissected region. To demonstrate further the utility of the sublibrary, a 150-kb contig containing the SAS and CDK4 genes was constructed, as well as several additional contigs between CDK4 and MDM2. This study demonstrates the possibility of utilizing probes generated by microdissection for assembling band-specific libraries that are amendable to rapid screening with multiple markers.

Primary myelodysplastic syndrome with complex chromosomal rearrangements in a patient with Klinefelter's syndrome.

OpenAIRE

Abidi, S M; Griffiths, M; Oscier, D G; Mufti, G J; Hamblin, T J

1986-01-01

A patient with Klinefelter's syndrome and diabetes mellitus was diagnosed as having myelodysplasia. Cytogenetic analysis of the peripheral blood and the bone marrow cells confirmed the presence of a constitutional 47,XXY chromosome complement. In addition, complex karyotypic abnormalities were present.

Rise, fall and resurrection of chromosome territories: a historical perspective. Part I. The rise of chromosome territories

OpenAIRE

T Cremer; C Cremer

2009-01-01

It is now generally accepted that chromosomes in the cell nucleus are organized in distinct domains, first called chromosome territories in 1909 by the great cytologist Theodor Boveri. Yet, even today chromosomes have remained enigmatic individuals, whose structures, arrangements and functions in cycling and post-mitotic cells still need to be explored in full detail. Whereas numerous recent reviews describe present evidence for a dynamic architecture of chromosome territories and discuss the...

Chromosomal Evolution in Chiroptera.

Science.gov (United States)

Sotero-Caio, Cibele G; Baker, Robert J; Volleth, Marianne

2017-10-13

Chiroptera is the second largest order among mammals, with over 1300 species in 21 extant families. The group is extremely diverse in several aspects of its natural history, including dietary strategies, ecology, behavior and morphology. Bat genomes show ample chromosome diversity (from 2n = 14 to 62). As with other mammalian orders, Chiroptera is characterized by clades with low, moderate and extreme chromosomal change. In this article, we will discuss trends of karyotypic evolution within distinct bat lineages (especially Phyllostomidae, Hipposideridae and Rhinolophidae), focusing on two perspectives: evolution of genome architecture, modes of chromosomal evolution, and the use of chromosome data to resolve taxonomic problems.

Chromosomal Evolution in Chiroptera

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Cibele G. Sotero-Caio

2017-10-01

Full Text Available Chiroptera is the second largest order among mammals, with over 1300 species in 21 extant families. The group is extremely diverse in several aspects of its natural history, including dietary strategies, ecology, behavior and morphology. Bat genomes show ample chromosome diversity (from 2n = 14 to 62. As with other mammalian orders, Chiroptera is characterized by clades with low, moderate and extreme chromosomal change. In this article, we will discuss trends of karyotypic evolution within distinct bat lineages (especially Phyllostomidae, Hipposideridae and Rhinolophidae, focusing on two perspectives: evolution of genome architecture, modes of chromosomal evolution, and the use of chromosome data to resolve taxonomic problems.

Phylogenetic Distinctiveness of Middle Eastern and Southeast Asian Village Dog Y Chromosomes Illuminates Dog Origins

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Brown, Sarah K.; Pedersen, Niels C.; Jafarishorijeh, Sardar; Bannasch, Danika L.; Ahrens, Kristen D.; Wu, Jui-Te; Okon, Michaella; Sacks, Benjamin N.

2011-01-01

Modern genetic samples are commonly used to trace dog origins, which entails untested assumptions that village dogs reflect indigenous ancestry or that breed origins can be reliably traced to particular regions. We used high-resolution Y chromosome markers (SNP and STR) and mitochondrial DNA to analyze 495 village dogs/dingoes from the Middle East and Southeast Asia, along with 138 dogs from >35 modern breeds to 1) assess genetic divergence between Middle Eastern and Southeast Asian village dogs and their phylogenetic affinities to Australian dingoes and gray wolves (Canis lupus) and 2) compare the genetic affinities of modern breeds to regional indigenous village dog populations. The Y chromosome markers indicated that village dogs in the two regions corresponded to reciprocally monophyletic clades, reflecting several to many thousand years divergence, predating the Neolithic ages, and indicating long-indigenous roots to those regions. As expected, breeds of the Middle East and East Asia clustered within the respective regional village dog clade. Australian dingoes also clustered in the Southeast Asian clade. However, the European and American breeds clustered almost entirely within the Southeast Asian clade, even sharing many haplotypes, suggesting a substantial and recent influence of East Asian dogs in the creation of European breeds. Comparison to 818 published breed dog Y STR haplotypes confirmed this conclusion and indicated that some African breeds reflect another distinct patrilineal origin. The lower-resolution mtDNA marker consistently supported Y-chromosome results. Both marker types confirmed previous findings of higher genetic diversity in dogs from Southeast Asia than the Middle East. Our findings demonstrate the importance of village dogs as windows into the past and provide a reference against which ancient DNA can be used to further elucidate origins and spread of the domestic dog. PMID:22194840

Naturally occurring minichromosome platforms in chromosome engineering: an overview.

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Raimondi, Elena

2011-01-01

Artificially modified chromosome vectors are non-integrating gene delivery platforms that can shuttle very large DNA fragments in various recipient cells: theoretically, no size limit exists for the chromosome segments that an engineered minichromosome can accommodate. Therefore, genetically manipulated chromosomes might be potentially ideal vector systems, especially when the complexity of higher eukaryotic genes is concerned. This review focuses on those chromosome vectors generated using spontaneously occurring small markers as starting material. The definition and manipulation of the centromere domain is one of the main obstacles in chromosome engineering: naturally occurring minichromosomes, due to their inherent small size, were helpful in defining some aspects of centromere function. In addition, several distinctive features of small marker chromosomes, like their appearance as supernumerary elements in otherwise normal karyotypes, have been successfully exploited to use them as gene delivery vectors. The key technologies employed for minichromosome engineering are: size reduction, gene targeting, and vector delivery in various recipient cells. In spite of the significant advances that have been recently achieved in all these fields, several unsolved problems limit the potential of artificially modified chromosomes. Still, these vector systems have been exploited in a number of applications where the investigation of the controlled expression of large DNA segments is needed. A typical example is the analysis of genes whose expression strictly depends on the chromosomal environment in which they are positioned, where engineered chromosomes can be envisaged as epigenetically regulated expression systems. A novel and exciting advance concerns the use of engineered minichromosomes to study the organization and dynamics of local chromatin structures.

Complex Variant t(9;22 Chromosome Translocations in Five Cases of Chronic Myeloid Leukemia

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Ana Valencia

2009-01-01

Full Text Available The Philadelphia (Ph1 chromosome arising from the reciprocal t(9;22 translocation is found in more than 90% of chronic myeloid leukemia (CML patients and results in the formation of the chimeric fusion gene BCR-ABL. However, a small proportion of patients with CML have simple or complex variants of this translocation, involving various breakpoints in addition to 9q34 and 22q11. We report five CML cases carrying variant Ph translocations involving both chromosomes 9 and 22 as well as chromosomes 3, 5, 7, 8, or 10. G-banding showed a reciprocal three-way translocation involving 3q21, 5q31, 7q32, 8q24, and 10q22 bands. BCR-ABL fusion signal on der(22 was found in all of the cases by FISH.

Analysis of Staphylococcal cassette chromosome mec in Staphylococcus haemolyticus and Staphylococcus sciuri: identification of a novel ccr gene complex with a newly identified ccrA allotype (ccrA7).

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Urushibara, Noriko; Paul, Shyamal Kumar; Hossain, Mohammad Akram; Kawaguchiya, Mitsuyo; Kobayashi, Nobumichi

2011-06-01

Methicillin resistance in staphylococci is conferred by the acquisition in its chromosome of the mecA gene, which is located on a mobile genetic element called staphylococcal cassette chromosome mec (SCCmec). Genetic type of SCCmec is defined by combination of mec gene complex class and cassette chromosome recombinase gene (ccr) allotype. In this study, we analyzed genetic diversity of the SCCmec in 11 Staphylococcus haemolyticus strains and a Staphylococcus sciuri strain, which were recently isolated from clinical specimens in Bangladesh. Among these strains, only two S. haemolyticus strains were proved to have the known types of SCCmec, that is, SCCmec V (class C2 mec-ccrC) and VII (class C1 mec-ccrC). Five S. haemolyticus strains were assigned two unique mec-ccr gene complexes combination; that is, class C1 mec-ccrA4B4 (four isolates) and class A mec-ccrC (one isolate). In the remaining four S. haemolyticus strains with class C1 mec, no known ccr allotypes could be detected. A single S. sciuri strain with class A mec complex carried a ccrA gene belonging to a novel allotype designated ccrA7, together with ccrB3. The ccrA7 gene in the S. sciuri strain showed 61.7%-82.7% sequence identity to the ccrA gene sequences published so far, and 75.3% identity to ccrA3, which is a component of the type 3 ccr complex (ccrA3-ccrB3) in methicillin-resistant Staphylococcus aureus. The results of the present study indicated that mec gene complex and ccr genes in coagulase-negative staphylococci are highly divergent, and distinct from those of common methicillin-resistant S. aureus. Identification of the novel ccrA7 allotype combined with ccrB3 suggested an occurrence of recombination between different ccr complexes in nature.

Interphase Chromosome Profiling: A Method for Conventional Banded Chromosome Analysis Using Interphase Nuclei.

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Babu, Ramesh; Van Dyke, Daniel L; Dev, Vaithilingam G; Koduru, Prasad; Rao, Nagesh; Mitter, Navnit S; Liu, Mingya; Fuentes, Ernesto; Fuentes, Sarah; Papa, Stephen

2018-02-01

- Chromosome analysis on bone marrow or peripheral blood samples fails in a small proportion of attempts. A method that is more reliable, with similar or better resolution, would be a welcome addition to the armamentarium of the cytogenetics laboratory. - To develop a method similar to banded metaphase chromosome analysis that relies only on interphase nuclei. - To label multiple targets in an equidistant fashion along the entire length of each chromosome, including landmark subtelomere and centromere regions. Each label so generated by using cloned bacterial artificial chromosome probes is molecularly distinct with unique spectral characteristics, so the number and position of the labels can be tracked to identify chromosome abnormalities. - Interphase chromosome profiling (ICP) demonstrated results similar to conventional chromosome analysis and fluorescence in situ hybridization in 55 previously studied cases and obtained useful ICP chromosome analysis results on another 29 cases in which conventional methods failed. - ICP is a new and powerful method to karyotype peripheral blood and bone marrow aspirate preparations without reliance on metaphase chromosome preparations. It will be of particular value for cases with a failed conventional analysis or when a fast turnaround time is required.

Low grade mosaic for a complex supernumerary ring chromosome 18 in an adult patient with multiple congenital anomalies

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Hoogeboom A Jeannette M

2010-07-01

Full Text Available Abstract Background Several cases have been reported of patients with a ring chromosome 18 replacing one of the normal chromosomes 18. Less common are patients with a supernumerary ring chromosomes 18. High resolution whole genome examination in patients with multiple congenital abnormalities might reveal cytogenetic abnormalities of an unexpected complexity. Results We report a 24 years old male patient with lower spinal anomalies, hypospadia, bifid scrotum, cryptorchism, anal atresia, kidney stones, urethra anomalies, radial dysplasia, and a hypoplastic thumb. Some of the anomalies overlap with the VACTERL association. Chromosome analysis of cultured peripheral blood lymphocytes revealed an additional ring chromosome in 13% of the metaphases. Both parents had a normal karyotype, demonstrating the de novo origin of this ring chromosome. FISH analysis using whole chromosome paints showed that the additional chromosomal material was derived from chromosome 18. Chromosome analysis of cultured fibroblasts revealed only one cell with the supernumerary ring chromosome in the 400 analyzed. To characterize the ring chromosome in more detail peripheral blood derived DNA was analyzed using SNP-arrays. The array results indicated a 5 Mb gain of the pericentromeric region of chromosome 18q10-q11.2. FISH analysis using BAC-probes located in the region indicated the presence of 6 signals on the r(18 chromosome. In addition, microsatellite analysis demonstrated that the unique supernumerary ring chromosome was paternally derived and both normal copies showed biparental disomy. Conclusions We report on an adult patient with multiple congenital abnormalities who had in 13% of his cells a unique supernumerary ring chromosome 18 that was composed of 6 copies of the 5 Mb gene rich region of 18q11.

De novo complex intra chromosomal rearrangement after ICSI: characterisation by BACs micro array-CGH

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Quimsiyeh Mazin

2008-12-01

Full Text Available Abstract Background In routine Assisted Reproductive Technology (ART men with severe oligozoospermia or azoospermia should be informed about the risk of de novo congenital or chromosomal abnormalities in ICSI program. Also the benefits of preimplantation or prenatal genetic diagnosis practice need to be explained to the couple. Methods From a routine ICSI attempt, using ejaculated sperm from male with severe oligozoospermia and having normal karyotype, a 30 years old pregnant woman was referred to prenatal diagnosis in the 17th week for bichorionic biamniotic twin gestation. Amniocentesis was performed because of the detection of an increased foetal nuchal translucency for one of the fetus by the sonographic examination during the 12th week of gestation (WG. Chromosome and DNA studies of the fetus were realized on cultured amniocytes Results Conventional, molecular cytogenetic and microarray CGH experiments allowed us to conclude that the fetus had a de novo pericentromeric inversion associated with a duplication of the 9p22.1-p24 chromosomal region, 46,XY,invdup(9(p22.1p24 [arrCGH 9p22.1p24 (RP11-130C19 → RP11-87O1x3]. As containing the critical 9p22 region, our case is in coincidence with the general phenotype features of the partial trisomy 9p syndrome with major growth retardation, microcephaly and microretrognathia. Conclusion This de novo complex chromosome rearrangement illustrates the possible risk of chromosome or gene defects in ICSI program and the contribution of array-CGH for mapping rapidly de novo chromosomal imbalance.

Stage-specific damage to synaptonemal complexes and metaphase chromosomes induced by X rays in male mouse germ cells

International Nuclear Information System (INIS)

Backer, L.C.; Sontag, M.R.; Allen, J.W.

1991-01-01

Synaptonemal complexes (SCs) reveal mutagen-induced effects in germ cell meiotic chromosomes. The study was aimed at characterizing relationships between SC and metaphase I chromosome damage following radiation exposure at various stages of spermatogenesis. Male mice were irradiated with doses of 0, 2, or 4 Gy, and spermatocytes were harvested at times consistent with earlier exposures as spermatogonial stem cells, preleptotene cells (premeiotic DNA synthesis), or meiotic prophase cells. After stem-cell exposure, twice as many rearrangements were observed in SCs as in metaphase I chromosomes. Irradiation during premeiotic DNA synthesis resulted in dose-related increases in SC breakage and rearrangements (including novel forms) and in metaphase chromosomal aberrations. Following prophase exposure, various types and levels of SC and metaphase damage were observed. Irradiation of zygotene cells led to high frequencies of chromosome multivalents in metaphase I without a correspondingly high level of damage in preceding prophase SCs. Thus, irradiation of premeiotic and meiotic cells results in variable relationships between SC and metaphase chromosome damage

Complex chromosome rearrangements related 15q14 microdeletion plays a relevant role in phenotype expression and delineates a novel recurrent syndrome

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Tomaiuolo Anna

2011-04-01

Full Text Available Abstract Complex chromosome rearrangements are constitutional structural rearrangements involving three or more chromosomes or having more than two breakpoints. These are rarely seen in the general population but their frequency should be much higher due to balanced states with no phenotypic presentation. These abnormalities preferentially occur de novo during spermatogenesis and are transmitted in families through oogenesis. Here, we report a de novo complex chromosome rearrangement that interests eight chromosomes in eighteen-year-old boy with an abnormal phenotype consisting in moderate developmental delay, cleft palate, and facial dysmorphisms. Standard G-banding revealed four apparently balanced traslocations involving the chromosomes 1;13, 3;19, 9;15 and 14;18 that appeared to be reciprocal. Array-based comparative genomic hybridization analysis showed no imbalances at all the breakpoints observed except for an interstitial microdeletion on chromosome 15. This deletion is 1.6 Mb in size and is located at chromosome band 15q14, distal to the Prader-Willi/Angelman region. Comparing the features of our patient with published reports of patients with 15q14 deletion this finding corresponds to the smallest genomic region of overlap. The deleted segment at 15q14 was investigated for gene content.

Application of molecular cytogenetic techniques to clarify apparently balanced complex chromosomal rearrangements in two patients with an abnormal phenotype: case report

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Rongen Michel A

2009-07-01

Full Text Available Abstract Background Complex chromosomal rearrangements (CCR are rare cytogenetic findings that are difficult to karyotype by conventional cytogenetic analysis partially because of the relative low resolution of this technique. High resolution genotyping is necessary in order to identify cryptic imbalances, for instance near the multiple breakpoints, to explain the abnormal phenotype in these patients. We applied several molecular techniques to elucidate the complexity of the CCRs of two adult patients with abnormal phenotypes. Results Multicolour fluorescence in situ hybridization (M-FISH showed that in patient 1 the chromosomes 1, 10, 15 and 18 were involved in the rearrangement whereas for patient 2 the chromosomes 5, 9, 11 and 13 were involved. A 250 k Nsp1 SNP-array analysis uncovered a deletion in chromosome region 10p13 for patient 1, harbouring 17 genes, while patient 2 showed no pathogenic gains or losses. Additional FISH analysis with locus specific BAC-probes was performed, leading to the identification of cryptic interstitial structural rearrangements in both patients. Conclusion Application of M-FISH and SNP-array analysis to apparently balanced CCRs is useful to delineate the complex chromosomal rearrangement in detail. However, it does not always identify cryptic imbalances as an explanation for the abnormal phenotype in patients with a CCR.

Submicroscopic interstitial deletion of the X chromosome explains a complex genetic syndrome dominated by Norrie disease.

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Gal, A; Wieringa, B; Smeets, D F; Bleeker-Wagemakers, L; Ropers, H H

1986-01-01

Norrie disease (ND), an X-linked recessive disorder, is characterized by congenital blindness followed by bulbar atrophy. We have examined a three-generation family in which ND is part of a complex X-linked syndrome with severe mental retardation, hypogonadism, growth disturbances, and increased susceptibility to infections as additional features. This syndrome is apparently due to an interstitial deletion, as evidenced by the failure of the L1.28 DNA probe (DXS7 locus, Xp11.3) to detect complementary DNA sequences on the defective X chromosome of an affected male and of several obligatory heterozygotes. Attempts to further define this deletion with other DNA probes from the proximal short arm of the X chromosome or by prometaphase chromosome analysis were unsuccessful.

Non-SMC condensin I complex proteins control chromosome segregation and survival of proliferating cells in the zebrafish neural retina

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Harris William A

2009-07-01

Full Text Available Abstract Background The condensation of chromosomes and correct sister chromatid segregation during cell division is an essential feature of all proliferative cells. Structural maintenance of chromosomes (SMC and non-SMC proteins form the condensin I complex and regulate chromosome condensation and segregation during mitosis. However, due to the lack of appropriate mutants, the function of the condensin I complex during vertebrate development has not been described. Results Here, we report the positional cloning and detailed characterization of retinal phenotypes of a zebrafish mutation at the cap-g locus. High resolution live imaging reveals that the progression of mitosis between prometa- to telophase is delayed and that sister chromatid segregation is impaired upon loss of CAP-G. CAP-G associates with chromosomes between prometa- and telophase of the cell cycle. Loss of the interaction partners CAP-H and CAP-D2 causes cytoplasmic mislocalization of CAP-G throughout mitosis. DNA content analysis reveals increased genomic imbalances upon loss of non-SMC condensin I subunits. Within the retina, loss of condensin I function causes increased rates of apoptosis among cells within the proliferative ciliary marginal zone (CMZ whereas postmitotic retinal cells are viable. Inhibition of p53-mediated apoptosis partially rescues cell numbers in cap-g mutant retinae and allows normal layering of retinal cell types without alleviating their aberrant nuclear sizes. Conclusion Our findings indicate that the condensin I complex is particularly important within rapidly amplifying progenitor cell populations to ensure faithful chromosome segregation. In contrast, differentiation of postmitotic retinal cells is not impaired upon polyploidization.

Clinical array-based karyotyping of breast cancer with equivocal HER2 status resolves gene copy number and reveals chromosome 17 complexity

International Nuclear Information System (INIS)

Gunn, Shelly; Gorre, Mercedes; Mohammed, Mansoor; Yeh, I-Tien; Lytvak, Irina; Tirtorahardjo, Budi; Dzidic, Natasha; Zadeh, Soheila; Kim, Jaeweon; McCaskill, Chris; Lim, Lony

2010-01-01

HER2 gene copy status, and concomitant administration of trastuzumab (Herceptin), remains one of the best examples of targeted cancer therapy based on understanding the genomic etiology of disease. However, newly diagnosed breast cancer cases with equivocal HER2 results present a challenge for the oncologist who must make treatment decisions despite the patient's unresolved HER2 status. In some cases both immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) are reported as equivocal, whereas in other cases IHC results and FISH are discordant for positive versus negative results. The recent validation of array-based, molecular karyotyping for clinical oncology testing provides an alternative method for determination of HER2 gene copy number status in cases remaining unresolved by traditional methods. In the current study, DNA extracted from 20 formalin fixed paraffin embedded (FFPE) tissue samples from newly diagnosed cases of invasive ductal carcinoma referred to our laboratory with unresolved HER2 status, were analyzed using a clinically validated genomic array containing 127 probes covering the HER2 amplicon, the pericentromeric regions, and both chromosome 17 arms. Array-based comparative genomic hybridization (array CGH) analysis of chromosome 17 resolved HER2 gene status in [20/20] (100%) of cases and revealed additional chromosome 17 copy number changes in [18/20] (90%) of cases. Array CGH analysis also revealed two false positives and one false negative by FISH due to 'ratio skewing' caused by chromosomal gains and losses in the centromeric region. All cases with complex rearrangements of chromosome 17 showed genome-wide chromosomal instability. These results illustrate the analytical power of array-based genomic analysis as a clinical laboratory technique for resolution of HER2 status in breast cancer cases with equivocal results. The frequency of complex chromosome 17 abnormalities in these cases suggests that the two

The SMC-5/6 Complex and the HIM-6 (BLM Helicase Synergistically Promote Meiotic Recombination Intermediate Processing and Chromosome Maturation during Caenorhabditis elegans Meiosis.

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Ye Hong

2016-03-01

Full Text Available Meiotic recombination is essential for the repair of programmed double strand breaks (DSBs to generate crossovers (COs during meiosis. The efficient processing of meiotic recombination intermediates not only needs various resolvases but also requires proper meiotic chromosome structure. The Smc5/6 complex belongs to the structural maintenance of chromosome (SMC family and is closely related to cohesin and condensin. Although the Smc5/6 complex has been implicated in the processing of recombination intermediates during meiosis, it is not known how Smc5/6 controls meiotic DSB repair. Here, using Caenorhabditis elegans we show that the SMC-5/6 complex acts synergistically with HIM-6, an ortholog of the human Bloom syndrome helicase (BLM during meiotic recombination. The concerted action of the SMC-5/6 complex and HIM-6 is important for processing recombination intermediates, CO regulation and bivalent maturation. Careful examination of meiotic chromosomal morphology reveals an accumulation of inter-chromosomal bridges in smc-5; him-6 double mutants, leading to compromised chromosome segregation during meiotic cell divisions. Interestingly, we found that the lethality of smc-5; him-6 can be rescued by loss of the conserved BRCA1 ortholog BRC-1. Furthermore, the combined deletion of smc-5 and him-6 leads to an irregular distribution of condensin and to chromosome decondensation defects reminiscent of condensin depletion. Lethality conferred by condensin depletion can also be rescued by BRC-1 depletion. Our results suggest that SMC-5/6 and HIM-6 can synergistically regulate recombination intermediate metabolism and suppress ectopic recombination by controlling chromosome architecture during meiosis.

The SMC-5/6 Complex and the HIM-6 (BLM) Helicase Synergistically Promote Meiotic Recombination Intermediate Processing and Chromosome Maturation during Caenorhabditis elegans Meiosis.

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Hong, Ye; Sonneville, Remi; Agostinho, Ana; Meier, Bettina; Wang, Bin; Blow, J Julian; Gartner, Anton

2016-03-01

Meiotic recombination is essential for the repair of programmed double strand breaks (DSBs) to generate crossovers (COs) during meiosis. The efficient processing of meiotic recombination intermediates not only needs various resolvases but also requires proper meiotic chromosome structure. The Smc5/6 complex belongs to the structural maintenance of chromosome (SMC) family and is closely related to cohesin and condensin. Although the Smc5/6 complex has been implicated in the processing of recombination intermediates during meiosis, it is not known how Smc5/6 controls meiotic DSB repair. Here, using Caenorhabditis elegans we show that the SMC-5/6 complex acts synergistically with HIM-6, an ortholog of the human Bloom syndrome helicase (BLM) during meiotic recombination. The concerted action of the SMC-5/6 complex and HIM-6 is important for processing recombination intermediates, CO regulation and bivalent maturation. Careful examination of meiotic chromosomal morphology reveals an accumulation of inter-chromosomal bridges in smc-5; him-6 double mutants, leading to compromised chromosome segregation during meiotic cell divisions. Interestingly, we found that the lethality of smc-5; him-6 can be rescued by loss of the conserved BRCA1 ortholog BRC-1. Furthermore, the combined deletion of smc-5 and him-6 leads to an irregular distribution of condensin and to chromosome decondensation defects reminiscent of condensin depletion. Lethality conferred by condensin depletion can also be rescued by BRC-1 depletion. Our results suggest that SMC-5/6 and HIM-6 can synergistically regulate recombination intermediate metabolism and suppress ectopic recombination by controlling chromosome architecture during meiosis.

Cloning and chromosomal localization of the three human syntrophin genes

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Feener, C.A.; Anderson, M.D.S.; Selig, S. [Children`s Hospital, Boston, MA (United States)] [and others

1994-09-01

Dystrophin, the protein product the Duchenne muscular dystrophy locus, is normally found to be associated with a complex of proteins. Among these dystrophin-associated proteins are the syntrophins, a group of 59 kDa membrane-associated proteins. When the syntrophins are purified based upon their association with dystrophin, they have been shown previously to form two distinct groups, the acidic ({alpha}) and basic ({beta}) forms. Based on peptide and rodent cDNA sequences, three separate syntrophin genes have been cloned and characterized from human tissues. The predicted amino acid sequences from these cDNA reveal that these proteins are related but are distinct with respect to charge, as predicted from their biochemistry. The family consists of one acidic ({alpha}-syntrophin, analogous to mouse syntrophin-1) and two basic ({beta}{sub 1}-syntrophin; and {beta}{sub 2}-syntrophin, analogous to mouse syntrophin-2) genes. Each of the three genes are widely expressed in a variety of human tissues, but the relative abundance of the three are unique with respect to each other. {alpha}-syntrophin is expressed primarily in skeletal muscle and heart as a single transcript. {beta}{sub 1}-syntrophin is expressed widely in up to five distinct transcript sizes, and is most abundant in brain. The human chromosomal locations of the three syntrophins are currently being mapped. {beta}{sub 1}-syntrophin maps to chromosome 8q23-24 and {beta}{sub 2}-syntrophin to chromosome 16. The {alpha}-syntrophin gene will be mapped accordingly. Although all three genes are candidates for neuromuscular diseases, the predominant expression of {alpha}-syntrophin in skeletal muscle and heart makes it a strong candidate to be involved in a neuromuscular disease.

cis-Acting Complex-Trait-Associated lincRNA Expression Correlates with Modulation of Chromosomal Architecture

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Jennifer Yihong Tan

2017-02-01

Full Text Available Summary: Intergenic long noncoding RNAs (lincRNAs are the largest class of transcripts in the human genome. Although many have recently been linked to complex human traits, the underlying mechanisms for most of these transcripts remain undetermined. We investigated the regulatory roles of a high-confidence and reproducible set of 69 trait-relevant lincRNAs (TR-lincRNAs in human lymphoblastoid cells whose biological relevance is supported by their evolutionary conservation during recent human history and genetic interactions with other trait-associated loci. Their enrichment in enhancer-like chromatin signatures, interactions with nearby trait-relevant protein-coding loci, and preferential location at topologically associated domain (TAD boundaries provide evidence that TR-lincRNAs likely regulate proximal trait-relevant gene expression in cis by modulating local chromosomal architecture. This is consistent with the positive and significant correlation found between TR-lincRNA abundance and intra-TAD DNA-DNA contacts. Our results provide insights into the molecular mode of action by which TR-lincRNAs contribute to complex human traits. : Tan et al. identify and characterize 69 human complex trait/disease-associated lincRNAs in LCLs. They show that these loci are often associated with cis-regulation of gene expression and tend to be localized at TAD boundaries, suggesting that these lincRNAs may influence chromosomal architecture. Keywords: intergenic long noncoding RNA, lincRNA, GWAS, expression quantitative trait loci, eQTL, complex trait and disease, enhancer, cis-regulation, topologically associated domains, TAD

Modeling and experimental methods to probe the link between global transcription and spatial organization of chromosomes.

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K Venkatesan Iyer

Full Text Available Genomes are spatially assembled into chromosome territories (CT within the nucleus of living cells. Recent evidences have suggested associations between three-dimensional organization of CTs and the active gene clusters within neighboring CTs. These gene clusters are part of signaling networks sharing similar transcription factor or other downstream transcription machineries. Hence, presence of such gene clusters of active signaling networks in a cell type may regulate the spatial organization of chromosomes in the nucleus. However, given the probabilistic nature of chromosome positions and complex transcription factor networks (TFNs, quantitative methods to establish their correlation is lacking. In this paper, we use chromosome positions and gene expression profiles in interphase fibroblasts and describe methods to capture the correspondence between their spatial position and expression. In addition, numerical simulations designed to incorporate the interacting TFNs, reveal that the chromosome positions are also optimized for the activity of these networks. These methods were validated for specific chromosome pairs mapped in two distinct transcriptional states of T-Cells (naïve and activated. Taken together, our methods highlight the functional coupling between topology of chromosomes and their respective gene expression patterns.

A paternally transmitted complex chromosomal rearrangement (CCR) involving chromosomes 2, 6, and 18 includes eight breakpoints and five insertional translocations (ITs) through three generations.

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Gruchy, Nicolas; Barreau, Morgane; Kessler, Ketty; Gourdier, Dominique; Leporrier, Nathalie

2010-01-01

Complex chromosomal rearrangements (CCRs) are uncommon and mainly occur de novo. We report here on a familial CCR involving chromosomes 2, 6, and 18. The propositus is a boy first referred because of growth delays, hypotonia, and facial anomalies, suggestive of deletion 18q syndrome. However, a cytogenetic family study disclosed a balanced CCR in three generations, which was detailed by FISH using BAC clones, and consisted of eight breakpoints with five insertional translocations (ITs). The propositus had a cryptic 18q deletion and a 6p duplication. Paternal transmission of this CCR was observed through three generations without meiotic recombination. Our investigation allowed us to provide porosities counseling and management of prenatal diagnosis for propositus cousin who carries this particular CCR.

Genome-wide detection of chromosomal rearrangements, indels, and mutations in circular chromosomes by short read sequencing

DEFF Research Database (Denmark)

Skovgaard, Ole; Bak, Mads; Løbner-Olesen, Anders

2011-01-01

a combination of WGS and genome copy number analysis, for the identification of mutations that suppress the growth deficiency imposed by excessive initiations from the Escherichia coli origin of replication, oriC. The E. coli chromosome, like the majority of bacterial chromosomes, is circular, and DNA...... replication is initiated by assembling two replication complexes at the origin, oriC. These complexes then replicate the chromosome bidirectionally toward the terminus, ter. In a population of growing cells, this results in a copy number gradient, so that origin-proximal sequences are more frequent than...... origin-distal sequences. Major rearrangements in the chromosome are, therefore, readily identified by changes in copy number, i.e., certain sequences become over- or under-represented. Of the eight mutations analyzed in detail here, six were found to affect a single gene only, one was a large chromosomal...

Mapping of four distinct BCR-related loci to chromosome region 22q11: order of BCR loci relative to chronic myelogenous leukemia and acute lymphoblastic leukemia breakpoints

International Nuclear Information System (INIS)

Croce, C.M.; Huebner, K.; Isobe, M.; Fainstain, E.; Lifshitz, B.; Shtivelman, E.; Canaani, E.

1987-01-01

A probe derived from the 3' region of the BCR gene (breakpoint cluster region gene) detects four distinct loci in the human genome. One of the loci corresponds to the complete BCR gene, whereas the other contain a 3' segment of the gene. After HindIII cleavage of human DNA, these four loci are detected as 23-, 19-, 13-, and 9-kikobase-pair fragments, designated BCR4, BCR3, BCR2, and BCR1, respectively, with BCR1 deriving from the original complete BCR gene. All four BCR loci segregate 100% concordantly with human chromosome 22 in a rodent-human somatic cell hybrid panel and are located at chromosome region 22q11.2 by chromosomal in situ hybridization. The BCR2 and BCR4 loci are amplified in leukemia cell line K562 cells, indicating that they fall within the amplification unit that includes immunoglobulin λ light chain locus (IGL) and ABL locus on the K562 Philadelphia chromosome (Ph 1 ). Similarly, in mouse-human hybrids retaining a Ph 1 chromosome derived from an acute lymphoblastic leukemia-in the absence of the 9q + and 22, only BCR2 and BCR4 loci are retained. Thus, the order of loci on chromosome 22 is centromere → BCR2, BCR4, and IGL → BCR1 → BCR3 → SIS, possibly eliminating BCR2 and BCR4 loci as candidate targets for juxtaposition to the ABL gene in the acute lymphoblastic leukemia Ph 1 chromosome

BioNano genome mapping of individual chromosomes supports physical mapping and sequence assembly in complex plant genomes.

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Staňková, Helena; Hastie, Alex R; Chan, Saki; Vrána, Jan; Tulpová, Zuzana; Kubaláková, Marie; Visendi, Paul; Hayashi, Satomi; Luo, Mingcheng; Batley, Jacqueline; Edwards, David; Doležel, Jaroslav; Šimková, Hana

2016-07-01

The assembly of a reference genome sequence of bread wheat is challenging due to its specific features such as the genome size of 17 Gbp, polyploid nature and prevalence of repetitive sequences. BAC-by-BAC sequencing based on chromosomal physical maps, adopted by the International Wheat Genome Sequencing Consortium as the key strategy, reduces problems caused by the genome complexity and polyploidy, but the repeat content still hampers the sequence assembly. Availability of a high-resolution genomic map to guide sequence scaffolding and validate physical map and sequence assemblies would be highly beneficial to obtaining an accurate and complete genome sequence. Here, we chose the short arm of chromosome 7D (7DS) as a model to demonstrate for the first time that it is possible to couple chromosome flow sorting with genome mapping in nanochannel arrays and create a de novo genome map of a wheat chromosome. We constructed a high-resolution chromosome map composed of 371 contigs with an N50 of 1.3 Mb. Long DNA molecules achieved by our approach facilitated chromosome-scale analysis of repetitive sequences and revealed a ~800-kb array of tandem repeats intractable to current DNA sequencing technologies. Anchoring 7DS sequence assemblies obtained by clone-by-clone sequencing to the 7DS genome map provided a valuable tool to improve the BAC-contig physical map and validate sequence assembly on a chromosome-arm scale. Our results indicate that creating genome maps for the whole wheat genome in a chromosome-by-chromosome manner is feasible and that they will be an affordable tool to support the production of improved pseudomolecules. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Comparative Chromosome Map and Heterochromatin Features of the Gray Whale Karyotype (Cetacea).

Science.gov (United States)

Kulemzina, Anastasia I; Proskuryakova, Anastasia A; Beklemisheva, Violetta R; Lemskaya, Natalia A; Perelman, Polina L; Graphodatsky, Alexander S

2016-01-01

Cetacean karyotypes possess exceptionally stable diploid numbers and highly conserved chromosomes. To date, only toothed whales (Odontoceti) have been analyzed by comparative chromosome painting. Here, we studied the karyotype of a representative of baleen whales, the gray whale (Eschrichtius robustus, Mysticeti), by Zoo-FISH with dromedary camel and human chromosome-specific probes. We confirmed a high degree of karyotype conservation and found an identical order of syntenic segments in both branches of cetaceans. Yet, whale chromosomes harbor variable heterochromatic regions constituting up to a third of the genome due to the presence of several types of repeats. To investigate the cause of this variability, several classes of repeated DNA sequences were mapped onto chromosomes of whale species from both Mysticeti and Odontoceti. We uncovered extensive intrapopulation variability in the size of heterochromatic blocks present in homologous chromosomes among 3 individuals of the gray whale by 2-step differential chromosome staining. We show that some of the heteromorphisms observed in the gray whale karyotype are due to distinct amplification of a complex of common cetacean repeat and heavy satellite repeat on homologous autosomes. Furthermore, we demonstrate localization of the telomeric repeat in the heterochromatin of both gray and pilot whale (Globicephala melas, Odontoceti). Heterochromatic blocks in the pilot whale represent a composite of telomeric and common repeats, while heavy satellite repeat is lacking in the toothed whale consistent with previous studies. © 2016 S. Karger AG, Basel.

Analysis of the Ceratitis capitata y chromosome using in situ hybridization to mitotic chromosomes

International Nuclear Information System (INIS)

Willhoeft, U.; Franz, G.

1998-01-01

In Ceratitis capitata the Y chromosome is responsible for sex-determination. We used fluorescence in situ hybridization (FISH) for cytogenetic analysis of mitotic chromosomes. FISH with the wild-type strain EgyptII and two repetitive DNA probes enabled us to differentiate between the short and the long arm of the Y chromosome and gives a much better resolution than C-banding of mitotic chromosomes. We identified the Y-chromosomal breakpoints in Y-autosome translocations using FISH. Even more complex rearrangements i.e. deletions and insertions in some translocation strains were detected by this method. A strategy for mapping the primary sex determination factor in Ceratitis capitata by FISH is presented. (author)

Rise, fall and resurrection of chromosome territories: a historical perspective. Part I. The rise of chromosome territories

Directory of Open Access Journals (Sweden)

T Cremer

2009-06-01

Full Text Available It is now generally accepted that chromosomes in the cell nucleus are organized in distinct domains, first called chromosome territories in 1909 by the great cytologist Theodor Boveri. Yet, even today chromosomes have remained enigmatic individuals, whose structures, arrangements and functions in cycling and post-mitotic cells still need to be explored in full detail. Whereas numerous recent reviews describe present evidence for a dynamic architecture of chromosome territories and discuss the potential significance within the functional compartmentalization of the nucleus, a comprehensive historical account of this important concept of nuclear organization was lacking so far. Here, we describe the early rise of chromosome territories within the context of the discovery of chromosomes and their fundamental role in heredity, covering a period from the 1870th to the early 20th century (part I, this volume. In part II (next volume we review the abandonment of the chromosome territory concept during the 1950th to 1980th and the compelling evidence, which led to its resurrection during the 1970th to 1980th.

No increase in radiation-induced chromosome aberration complexity detected by m-FISH after culture in the presence of 5'-bromodeoxyuridine

International Nuclear Information System (INIS)

Sumption, Natalia D.; Goodhead, Dudley T.; Anderson, Rhona M.

2006-01-01

The thymidine analogue, 5'-bromodeoxyuridine (BrdU), is a known mutagen that is routinely introduced into culture media for subsequent Harlequin stain analysis and determination of cell cycle status. Previously, we examined the induction of chromosome aberrations in human peripheral blood lymphocytes (PBL) known to be in their 1st cell division following exposure to a low dose (0.5 Gy, average one α-particle per cell) of high-LET α-particles. We found complex chromosome aberrations to be characteristic of exposure to high-LET radiation and suggested the features of complex exchange to reflect qualitatively the spatial deposition of this densely ionising radiation. To exclude the possibility that BrdU addition post-irradiation influenced the complexity of chromosomal damage observed by m-FISH, the effect of increasing BrdU concentration on aberration complexity was investigated. Comparisons between BrdU concentration (0, 10 and 40 μM) and between sham- and α-particle-irradiated PBL, were made both independently and in combination to enable discrimination between BrdU and high-LET radiation effects. Aberration type, size, complexity and completeness were assessed by m-FISH, and the relative progression through cell division was evaluated. We found no evidence of any qualitative difference in the complexity of damage as visualised by m-FISH but did observe an increase in the frequency of complex exchanges with increasing BrdU concentration indicative of altered cell cycle kinetics. The parameters measured here are consistent with findings from previous in vitro and in vivo work, indicating that each complex aberration visualised by m-FISH is characteristic of the structure of the high-LET α-particle track and the geometry of cell irradiated

Telomere dysfunction and cell survival: Roles for distinct TIN2-containing complexes

Energy Technology Data Exchange (ETDEWEB)

Kim, Sahn-ho; Davalos, Albert R.; Heo, Seok-Jin; Rodier, Francis; Zou, Ying; Beausejour, Christian; Kaminker, Patrick; Yannone, Steven M.; Campisi, Judith

2007-10-02

Telomeres are maintained by three DNA binding proteins (TRF1, TRF2 and POT1), and several associated factors. One factor, TIN2, binds TRF1 and TRF2 directly and POT1 indirectly. Along with two other proteins, TPP1 and hRap1, these form a soluble complex that may be the core telomere maintenance complex. It is not clear whether sub-complexes also exist in vivo. We provide evidence for two TIN2 sub-complexes with distinct functions in human cells. We isolated these two TIN2 sub-complexes from nuclear lysates of unperturbed cells and cells expressing TIN2 mutants TIN2-13, TIN2-15C, which cannot bind TRF2 or TRF1, respectively. In cells with wild-type p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere uncapping and eventual growth arrest. In cells lacking p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere dysfunction and cell death. Our findings suggest that distinct TIN2 complexes exist, and that TIN2-15C-sensitive subcomplexes are particularly important for cell survival in the absence of functional p53.

The impact of complex chromosomal rearrangements on the detection of radiosensitivity in cancer patients

International Nuclear Information System (INIS)

Neubauer, Susann; Dunst, Juergen; Gebhart, Erich

1997-01-01

Background and purpose: Lymphocytes of a small fraction of cancer patients responded to in vitro irradiation with an extreme chromosomal reaction. A large portion of the observed chromosome aberrations were complex chromosomal rearrangements (CCR). The present study is an attempt to define the impact of CCR on the predictive detection of an intrinsic clinical radiosensitivity in cancer patients in more detail. Materials and methods: A three-colour 'FISH-painting' technique (chromosome in situ suppression (CISS) hybridization) was used for the detection of chromosomal rearrangements, induced by in vitro irradiation, in 81 samples of peripheral blood lymphocytes from 66 cancer patients. Thirty-three of those were assigned for radiation therapy, the others having just undergone radiation therapy. Seven healthy individuals served as controls. Results: CCRs are a very rare event in non-irradiated cells. Lymphocytes of patients who had just undergone therapeutic irradiation, however, not only exhibited high basic frequencies of CCR but also responded to in vitro irradiation with a more drastic increase of CCR than did the lymphocytes of non-exposed patients. A high inter-individual variability of the reaction to in vitro irradiation could be generally stated. The lymphocytes of patients with clinical signs of an outstanding radiosensitivity responded with an unusually high frequency of CCR. The total number of CCRs detected by CISS was found to be dependent on the interval from a previous radiation therapy and was slightly influenced by previous cytostatic therapy. Irrespective of these influences, patients with clinically defined radiation hypersensitivity were those with the highest radiosensitivity also in cytogenetic terms (including CCR). Conclusion: The successful use of FISH-painting for the detection of CCR, in addition to the general breakage frequency, highlights its suitability in the identification of individual hypersensitivity to ionizing radiation. The

A familial Cri-du-Chat/5p deletion syndrome resulted from rare maternal complex chromosomal rearrangements (CCRs and/or possible chromosome 5p chromothripsis.

Directory of Open Access Journals (Sweden)

Heng Gu

Full Text Available Cri-du-Chat syndrome (MIM 123450 is a chromosomal syndrome characterized by the characteristic features, including cat-like cry and chromosome 5p deletions. We report a family with five individuals showing chromosomal rearrangements involving 5p, resulting from rare maternal complex chromosomal rearrangements (CCRs, diagnosed post- and pre-natally by comprehensive molecular and cytogenetic analyses. Two probands, including a 4½-year-old brother and his 2½-year- old sister, showed no diagnostic cat cry during infancy, but presented with developmental delay, dysmorphic and autistic features. Both patients had an interstitial deletion del(5(p13.3p15.33 spanning ≈ 26.22 Mb. The phenotypically normal mother had de novo CCRs involving 11 breakpoints and three chromosomes: ins(11;5 (q23;p14.1p15.31,ins(21;5(q21;p13.3p14.1,ins(21;5(q21;p15.31p15.33,inv(7(p22q32dn. In addition to these two children, she had three first-trimester miscarriages, two terminations due to the identification of the 5p deletion and one delivery of a phenotypically normal daughter. The unaffected daughter had the maternal ins(11;5 identified prenatally and an identical maternal allele haplotype of 5p. Array CGH did not detect any copy number changes in the mother, and revealed three interstitial deletions within 5p15.33-p13.3, in the unaffected daughter, likely products of the maternal insertions ins(21;5. Chromothripsis has been recently reported as a mechanism drives germline CCRs in pediatric patients with congenital defects. We postulate that the unique CCRs in the phenotypically normal mother could resulted from chromosome 5p chromothripsis, that further resulted in the interstitial 5p deletions in the unaffected daughter. Further high resolution sequencing based analysis is needed to determine whether chromothripsis is also present as a germline structural variation in phenotypically normal individuals in this family.

Memory Synapses Are Defined by Distinct Molecular Complexes: A Proposal.

Science.gov (United States)

Sossin, Wayne S

2018-01-01

Synapses are diverse in form and function. While there are strong evidential and theoretical reasons for believing that memories are stored at synapses, the concept of a specialized "memory synapse" is rarely discussed. Here, we review the evidence that memories are stored at the synapse and consider the opposing possibilities. We argue that if memories are stored in an active fashion at synapses, then these memory synapses must have distinct molecular complexes that distinguish them from other synapses. In particular, examples from Aplysia sensory-motor neuron synapses and synapses on defined engram neurons in rodent models are discussed. Specific hypotheses for molecular complexes that define memory synapses are presented, including persistently active kinases, transmitter receptor complexes and trans-synaptic adhesion proteins.

MLL/WDR5 Complex Regulates Kif2A Localization to Ensure Chromosome Congression and Proper Spindle Assembly during Mitosis.

Science.gov (United States)

Ali, Aamir; Veeranki, Sailaja Naga; Chinchole, Akash; Tyagi, Shweta

2017-06-19

Mixed-lineage leukemia (MLL), along with multisubunit (WDR5, RbBP5, ASH2L, and DPY30) complex catalyzes the trimethylation of H3K4, leading to gene activation. Here, we characterize a chromatin-independent role for MLL during mitosis. MLL and WDR5 localize to the mitotic spindle apparatus, and loss of function of MLL complex by RNAi results in defects in chromosome congression and compromised spindle formation. We report interaction of MLL complex with several kinesin and dynein motors. We further show that the MLL complex associates with Kif2A, a member of the Kinesin-13 family of microtubule depolymerase, and regulates the spindle localization of Kif2A during mitosis. We have identified a conserved WDR5 interaction (Win) motif, so far unique to the MLL family, in Kif2A. The Win motif of Kif2A engages in direct interactions with WDR5 for its spindle localization. Our findings highlight a non-canonical mitotic function of MLL complex, which may have a direct impact on chromosomal stability, frequently compromised in cancer. Copyright © 2017 Elsevier Inc. All rights reserved.

Shaping meiotic chromosomes with SUMO: a feedback loop controls the assembly of the synaptonemal complex in budding yeast

Directory of Open Access Journals (Sweden)

Hideo Tsubouchi

2016-02-01

Full Text Available The synaptonemal complex (SC is a meiosis-specific chromosomal structure in which homologous chromosomes are intimately linked through arrays of specialized proteins called transverse filaments (TF. Widely conserved in eukaryote meiosis, the SC forms during prophase I and is essential for accurate segregation of homologous chromosomes at meiosis I. However, the basic mechanism overlooking formation and regulation of the SC has been poorly understood. By using the budding yeast Saccharomyces cerevisiae, we recently showed that SC formation is controlled through the attachment of multiple molecules of small ubiquitin-like modifier (SUMO to a regulator of TF assembly. Intriguingly, this SUMOylation is activated by TF, implicating the involvement of a positive feedback loop in the control of SC assembly. We discuss the implication of this finding and possible involvement of a similar mechanism in regulating other processes.

Conserved chromosomal positions of dual domains of the ets protooncogene in cats, mice, and humans

International Nuclear Information System (INIS)

Watson, D.K.; McWilliams-Smith, M.J.; Kozak, C.

1986-01-01

The mammalian protooncogene homologue of the avian v-ets sequence from the E26 retrovirus consists of two sequentially distinct domains located on different chromosomes. Using somatic cell hybrid panels, the authors have mapped the mammalian homologue of the 5' v-ets-domain to chromosome 11 (ETS1) in man, to chromosome 9 (ets-1) in mouse, and to chromosome D1 (ETS1) in the domestic cat. The mammalian homologue of the 3' v-ets domain was similarly mapped to human chromosome 21 (ETS2), to mouse chromosome 16 (Ets-2), and to feline chromosome C2 (ETS2). Both protooncogenes fell in syntenic groups of homologous linked loci that were conserved among the three species. The occurrence of two distinct functional protooncogenes and their conservation of linkage positions in the three mammalian orders indicate that these two genes have been separate since before the evolutionary divergence of mammals

Novel types of staphylococcal cassette chromosome mec elements identified in clonal complex 398 methicillin-resistant Staphylococcus aureus strains.

NARCIS (Netherlands)

Li, S.; Skov, R.L.; Han, X.; Larsen, A.R.; Larsen, J.; Sorum, M.; Wulf, M.; Voss, A.; Hiramatsu, K.; Ito, T.

2011-01-01

The structures of staphylococcal cassette chromosome mec (SCCmec) elements carried by 31 clonal complex 398 (CC398) methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from the participants at a conference were analyzed. The SCCmecs were classified into novel types, namely, IX, X,

Synaptonemal complex aberrations in the pseudoautosomal region of X, Y chromosomes in irradiated hamsters

Energy Technology Data Exchange (ETDEWEB)

Allen, J.W.; Collins, B.W. [Environmental Protection Agency, Research Triangle Park, NC (United States); Poorman-Allen, P. [Wellcome Research Lab., Research Triangle Park, N.C. (United States); Sontag, M.R. [Duke Univ., Durham, NC (United States). Medical Center

1994-05-01

The effects of X-radiation, bleomycin and amsacrine (m-AMSA) on the meiotic chromosomes of male Armenian hamsters were determined by electron microscopic analysis of synaptonemal complex (SC) damage. Pachytene stage cells were analyzed 5 or 6 days following their treatment at putative preleptotene-leptotene stages of meiosis. Of the multiple types of SC aberrations observed to be significantly increased over control levels, lateral element breakage and synaptic anomalies were most prevalent. The focus of these studies was on the sex chromosomes which, in the Armenian hamster, reveal an unusally well-defined pseudoautosomal region. In the XY pair, radiation and chemical treatments caused certain forms of structural and synaptic anomalies which appeared to be preferentially localized to telomeric and/or crossover regions. The nature of these specific aberrations, involving breakage, bridge formation and asynapsis, is not well understood; however, their distributions are suggestive of possible relationships with sites and processes of crossing over. (author).

High-copy sequences reveal distinct evolution of the rye B chromosome

Czech Academy of Sciences Publication Activity Database

Klemme, S.; Banaei-Moghaddam, A.M.; Macas, Jiří; Wicker, T.; Novák, Petr; Houben, A.

2013-01-01

Roč. 199, č. 2 (2013), s. 550-558 ISSN 0028-646X R&D Projects: GA ČR GBP501/12/G090 Institutional support: RVO:60077344 Keywords : satellite DNA * nondisjunction control region * B chromosome * Secale cereale (rye) Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.545, year: 2013

The theory–practice distinction and the complexity of practical knowledge

Directory of Open Access Journals (Sweden)

Bonnie Miller-McLemore

2016-08-01

Full Text Available Over the past few decades, theologians have recognised the value of practice but have been optimistic about the ease with which practice is incorporated into theology. People use all sorts of adjectives to characterise the complex relationship – ‘integrally related’, a ‘deeper reciprocity’, ‘bound up in thickly intertwined ways’ – but connecting the two is not as easy as these words suggest. This article returns to the age-old question about the relationship between theory and practice. But it studies this question from the angle of practice. Although many scholars have analysed the distinction between theory and practice as it functions conceptually, few have examined challenges in relating the two as they emerge in practice. The article argues that there is an inevitable distinction between theory and practice that receives considerably less attention and needs more understanding and even respect. It also argues that the discipline of practical theology adds a distinctive angle on this discussion because it considers how the concepts function practically.

Understanding Chromosome Disorders and their Implications for Special Educators

Directory of Open Access Journals (Sweden)

Linda Gilmore

2014-03-01

Full Text Available More children are now being diagnosed with chromosome abnormalities. Some chromosome disorder syndromes are relatively well known; while others are so rare that there is only limited evidence about their likely impact on learning and development. For educators, a basic level of knowledge about chromosome abnormalities is important for understanding the literature and communicating with families and professionals. This paper describes chromosomes, and the numerical and structural anomalies that can occur, usually spontaneously during early cell division. Distinctive features of various chromosome syndromes are summarised before a discussion of the rare chromosome disorders that are labelled, not with a syndrome name, but simply by a description of the chromosome number, size and shape. Because of the potential within-group variability that characterises syndromes, and the scarcity of literature about the rare chromosome disorders, expectations for learning and development of individual students need to be based on the range of possible outcomes that may be achievable.

Mitotic chromosome condensation in vertebrates

International Nuclear Information System (INIS)

Vagnarelli, Paola

2012-01-01

Work from several laboratories over the past 10–15 years has revealed that, within the interphase nucleus, chromosomes are organized into spatially distinct territories [T. Cremer, C. Cremer, Chromosome territories, nuclear architecture and gene regulation in mammalian cells, Nat. Rev. Genet. 2 (2001) 292–301 and T. Cremer, M. Cremer, S. Dietzel, S. Muller, I. Solovei, S. Fakan, Chromosome territories—a functional nuclear landscape, Curr. Opin. Cell Biol. 18 (2006) 307–316]. The overall compaction level and intranuclear location varies as a function of gene density for both entire chromosomes [J.A. Croft, J.M. Bridger, S. Boyle, P. Perry, P. Teague,W.A. Bickmore, Differences in the localization and morphology of chromosomes in the human nucleus, J. Cell Biol. 145 (1999) 1119–1131] and specific chromosomal regions [N.L. Mahy, P.E. Perry, S. Gilchrist, R.A. Baldock, W.A. Bickmore, Spatial organization of active and inactive genes and noncoding DNA within chromosome territories, J. Cell Biol. 157 (2002) 579–589] (Fig. 1A, A'). In prophase, when cyclin B activity reaches a high threshold, chromosome condensation occurs followed by Nuclear Envelope Breakdown (NEB) [1]. At this point vertebrate chromosomes appear as compact structures harboring an attachment point for the spindle microtubules physically recognizable as a primary constriction where the two sister chromatids are held together. The transition from an unshaped interphase chromosome to the highly structured mitotic chromosome (compare Figs. 1A and B) has fascinated researchers for several decades now; however a definite picture of how this process is achieved and regulated is not yet in our hands and it will require more investigation to comprehend the complete process. From a biochemical point of view a vertebrate mitotic chromosomes is composed of DNA, histone proteins (60%) and non-histone proteins (40%) [6]. I will discuss below what is known to date on the contribution of these two different

Mitotic chromosome condensation in vertebrates

Energy Technology Data Exchange (ETDEWEB)

Vagnarelli, Paola, E-mail: P.Vagnarelli@ed.ac.uk

2012-07-15

Work from several laboratories over the past 10-15 years has revealed that, within the interphase nucleus, chromosomes are organized into spatially distinct territories [T. Cremer, C. Cremer, Chromosome territories, nuclear architecture and gene regulation in mammalian cells, Nat. Rev. Genet. 2 (2001) 292-301 and T. Cremer, M. Cremer, S. Dietzel, S. Muller, I. Solovei, S. Fakan, Chromosome territories-a functional nuclear landscape, Curr. Opin. Cell Biol. 18 (2006) 307-316]. The overall compaction level and intranuclear location varies as a function of gene density for both entire chromosomes [J.A. Croft, J.M. Bridger, S. Boyle, P. Perry, P. Teague,W.A. Bickmore, Differences in the localization and morphology of chromosomes in the human nucleus, J. Cell Biol. 145 (1999) 1119-1131] and specific chromosomal regions [N.L. Mahy, P.E. Perry, S. Gilchrist, R.A. Baldock, W.A. Bickmore, Spatial organization of active and inactive genes and noncoding DNA within chromosome territories, J. Cell Biol. 157 (2002) 579-589] (Fig. 1A, A'). In prophase, when cyclin B activity reaches a high threshold, chromosome condensation occurs followed by Nuclear Envelope Breakdown (NEB) [1]. At this point vertebrate chromosomes appear as compact structures harboring an attachment point for the spindle microtubules physically recognizable as a primary constriction where the two sister chromatids are held together. The transition from an unshaped interphase chromosome to the highly structured mitotic chromosome (compare Figs. 1A and B) has fascinated researchers for several decades now; however a definite picture of how this process is achieved and regulated is not yet in our hands and it will require more investigation to comprehend the complete process. From a biochemical point of view a vertebrate mitotic chromosomes is composed of DNA, histone proteins (60%) and non-histone proteins (40%) [6]. I will discuss below what is known to date on the contribution of these two different classes

Abnormal sex chromosome constitution and longitudinal growth

DEFF Research Database (Denmark)

Aksglaede, Lise; Skakkebaek, Niels E; Juul, Anders

2008-01-01

Growth is a highly complex process regulated by the interaction between sex steroids and the GH IGF-axis. However, other factors such as sex chromosome-related genes play independent roles.......Growth is a highly complex process regulated by the interaction between sex steroids and the GH IGF-axis. However, other factors such as sex chromosome-related genes play independent roles....

Chromosome painting reveals asynaptic full alignment of homologs and HIM-8-dependent remodeling of X chromosome territories during Caenorhabditis elegans meiosis.

Science.gov (United States)

Nabeshima, Kentaro; Mlynarczyk-Evans, Susanna; Villeneuve, Anne M

2011-08-01

During early meiotic prophase, a nucleus-wide reorganization leads to sorting of chromosomes into homologous pairs and to establishing associations between homologous chromosomes along their entire lengths. Here, we investigate global features of chromosome organization during this process, using a chromosome painting method in whole-mount Caenorhabditis elegans gonads that enables visualization of whole chromosomes along their entire lengths in the context of preserved 3D nuclear architecture. First, we show that neither spatial proximity of premeiotic chromosome territories nor chromosome-specific timing is a major factor driving homolog pairing. Second, we show that synaptonemal complex-independent associations can support full lengthwise juxtaposition of homologous chromosomes. Third, we reveal a prominent elongation of chromosome territories during meiotic prophase that initiates prior to homolog association and alignment. Mutant analysis indicates that chromosome movement mediated by association of chromosome pairing centers (PCs) with mobile patches of the nuclear envelope (NE)-spanning SUN-1/ZYG-12 protein complexes is not the primary driver of territory elongation. Moreover, we identify new roles for the X chromosome PC (X-PC) and X-PC binding protein HIM-8 in promoting elongation of X chromosome territories, separable from their role(s) in mediating local stabilization of pairing and association of X chromosomes with mobile SUN-1/ZYG-12 patches. Further, we present evidence that HIM-8 functions both at and outside of PCs to mediate chromosome territory elongation. These and other data support a model in which synapsis-independent elongation of chromosome territories, driven by PC binding proteins, enables lengthwise juxtaposition of chromosomes, thereby facilitating assessment of their suitability as potential pairing partners.

Growth Conditions Regulate the Requirements for Caulobacter Chromosome Segregation

DEFF Research Database (Denmark)

Shebelut, Conrad W.; Jensen, Rasmus Bugge; Gitai, Zemer

2009-01-01

Growth environments are important metabolic and developmental regulators. Here we demonstrate a growth environment-dependent effect on Caulobacter chromosome segregation of a small-molecule inhibitor of the MreB bacterial actin cytoskeleton. Our results also implicate ParAB as important segregation...... determinants, suggesting that multiple distinct mechanisms can mediate Caulobacter chromosome segregation and that their relative contributions can be environmentally regulated....

Localization to Chromosomes of Structural Genes for the Major Protease Inhibitors of Barley Grains

DEFF Research Database (Denmark)

Hejgaard, Jørn; Bjørn, S.E.; Nielsen, Gunnar Gissel

1984-01-01

Wheat-barley chromosome addition lines were compared by isoelectric focusing of protein extracts to identify chromosomes carrying loci for the major immunochemically distinct protease inhibitors of barley grains. Structural genes for the following inhibitors were localized: an inhibitor of both...... endogenous α-amylase 2 and subtilisin (ASI) on chromosome 2, two chymotrypsin/subtilisin inhibitors (CI-1 and CI-2) on chromosome 5 (long arm) and the major trypsin inhibitor (TI-1) on chromosome 3....

Condensins: universal organizers of chromosomes with diverse functions.

Science.gov (United States)

Hirano, Tatsuya

2012-08-01

Condensins are multisubunit protein complexes that play a fundamental role in the structural and functional organization of chromosomes in the three domains of life. Most eukaryotic species have two different types of condensin complexes, known as condensins I and II, that fulfill nonoverlapping functions and are subjected to differential regulation during mitosis and meiosis. Recent studies revealed that the two complexes contribute to a wide variety of interphase chromosome functions, such as gene regulation, recombination, and repair. Also emerging are their cell type- and tissue-specific functions and relevance to human disease. Biochemical and structural analyses of eukaryotic and bacterial condensins steadily uncover the mechanisms of action of this class of highly sophisticated molecular machines. Future studies on condensins will not only enhance our understanding of chromosome architecture and dynamics, but also help address a previously underappreciated yet profound set of questions in chromosome biology.

Telomere dysfunction and cell survival: roles for distinctTIN2-containing complexes

Energy Technology Data Exchange (ETDEWEB)

Kim, Sahn-Ho; Davalos, Albert R.; Heo, Seok-Jin; Rodier, Francis; Beausejour, Christian; Kaminker, Patrick; Campisi, Judith

2006-11-07

Telomeres are maintained by three DNA binding proteins, TRF1, TRF2 and POT1, and several associated factors. One factor, TIN2, binds TRF1 and TRF2 directly and POT1 indirectly. These and two other proteins form a soluble complex that may be the core telomere-maintenance complex. It is not clear whether subcomplexes exist or function in vivo. Here, we provide evidence for two TIN2 subcomplexes with distinct functions in human cells. TIN2 ablation by RNA interference caused telomere uncapping and p53-independent cell death in all cells tested. However, we isolated two TIN2 complexes from cell lysates, each selectively sensitive to a TIN2 mutant (TIN2-13, TIN2-15C). In cells with wild-type p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere uncapping and eventual growth arrest. In cells lacking p53 function, TIN215C more than TIN2-13 caused genomic instability and cell death. Thus, TIN2 subcomplexes likely have distinct functions in telomere maintenance, and may provide selective targets for eliminating cells with mutant p53.

Cephalosporium maydis is a distinct species in the Gaeumannomyces-Harpophora species complex.

Science.gov (United States)

Saleh, Amgad A; Leslie, John F

2004-01-01

Cephalosporium maydis is an important plant pathogen whose phylogenetic position relative to other fungi has not been established clearly. We compared strains of C. maydis, strains from several other plant-pathogenic Cephalosporium spp. and several possible relatives within the Gaeumannomyces-Harpophora species complex, to which C. maydis has been suggested to belong based on previous preliminary DNA sequence analyses. DNA sequences of the nuclear genes encoding the rDNA ITS region, β-tubulin, histone H3, and MAT-2 support the hypothesis that C. maydis is a distinct taxon within the Gaeumannomyces-Harpophora species complex. Based on amplified fragment length polymorphism (AFLP) profiles, C. maydis also is distinct from the other tested species of Cephalosporium, Phialophora sensu lato and members of Gaeumannomyces-Harpophora species complex, which supports its classification as Harpophora maydis. Oligonucleotide primers for H. maydis were developed that can be used in a PCR diagnostic protocol to rapidly and reliably detect and identify this pathogen. These diagnostic PCR primers will aid the detection of H. maydis in diseased maize because this fungus can be difficult to detect and isolate, and the movement of authentic cultures may be limited by quarantine restrictions.

Chromosome Painting Reveals Asynaptic Full Alignment of Homologs and HIM-8–Dependent Remodeling of X Chromosome Territories during Caenorhabditis elegans Meiosis

Science.gov (United States)

Nabeshima, Kentaro; Mlynarczyk-Evans, Susanna; Villeneuve, Anne M.

2011-01-01

During early meiotic prophase, a nucleus-wide reorganization leads to sorting of chromosomes into homologous pairs and to establishing associations between homologous chromosomes along their entire lengths. Here, we investigate global features of chromosome organization during this process, using a chromosome painting method in whole-mount Caenorhabditis elegans gonads that enables visualization of whole chromosomes along their entire lengths in the context of preserved 3D nuclear architecture. First, we show that neither spatial proximity of premeiotic chromosome territories nor chromosome-specific timing is a major factor driving homolog pairing. Second, we show that synaptonemal complex-independent associations can support full lengthwise juxtaposition of homologous chromosomes. Third, we reveal a prominent elongation of chromosome territories during meiotic prophase that initiates prior to homolog association and alignment. Mutant analysis indicates that chromosome movement mediated by association of chromosome pairing centers (PCs) with mobile patches of the nuclear envelope (NE)–spanning SUN-1/ZYG-12 protein complexes is not the primary driver of territory elongation. Moreover, we identify new roles for the X chromosome PC (X-PC) and X-PC binding protein HIM-8 in promoting elongation of X chromosome territories, separable from their role(s) in mediating local stabilization of pairing and association of X chromosomes with mobile SUN-1/ZYG-12 patches. Further, we present evidence that HIM-8 functions both at and outside of PCs to mediate chromosome territory elongation. These and other data support a model in which synapsis-independent elongation of chromosome territories, driven by PC binding proteins, enables lengthwise juxtaposition of chromosomes, thereby facilitating assessment of their suitability as potential pairing partners. PMID:21876678

Assignment of adenosine deaminase complexing protein (ADCP) gene(s) to human chromosome 2 in rodent-human somatic cell hybrids.

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Herbschleb-Voogt, E; Grzeschik, K H; Pearson, P L; Meera Khan, P

1981-01-01

The experiments reported in this paper indicate that the expression of human adenosine deaminase complexing protein (ADCP) in the human-rodent somatic cell hybrids is influenced by the state of confluency of the cells and the background rodent genome. Thus, the complement of the L-cell derived A9 or B82 mouse parent apparently prevents the expression of human ADCP in the interspecific somatic cell hybrids. In the a3, E36, or RAG hybrids the human ADCP expression was not prevented by the rodent genome and was found to be proportional to the degree of confluency of the cell in the culture as in the case of primary human fibroblasts. An analysis of human chromosomes, chromosome specific enzyme markers, and ADCP in a panel of rodent-human somatic cell hybrids optimally maintained and harvested at full confluency has shown that the expression of human ADCP in the mouse (RAG)-human as well as in the hamster (E36 or a3)-human hybrids is determined by a gene(s) in human chromosome 2 and that neither chromosome 6 nor any other of the chromosomes of man carry any gene(s) involved in the formation of human ADCP at least in the Chinese hamster-human hybrids. A series of rodent-human hybrid clones exhibiting a mitotic separation of IDH1 and MDH1 indicated that ADCP is most probably situated between corresponding loci in human chromosome 2.

DNA Repair Defects and Chromosomal Aberrations

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Hada, Megumi; George, K. A.; Huff, J. L.; Pluth, J. M.; Cucinotta, F. A.

2009-01-01

Yields of chromosome aberrations were assessed in cells deficient in DNA doublestrand break (DSB) repair, after exposure to acute or to low-dose-rate (0.018 Gy/hr) gamma rays or acute high LET iron nuclei. We studied several cell lines including fibroblasts deficient in ATM (ataxia telangiectasia mutated; product of the gene that is mutated in ataxia telangiectasia patients) or NBS (nibrin; product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase (DNA-PK) activity. Chromosomes were analyzed using the fluorescence in situ hybridization (FISH) chromosome painting method in cells at the first division post irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma irradiation induced greater yields of both simple and complex exchanges in the DSB repair-defective cells than in the normal cells. The quadratic dose-response terms for both simple and complex chromosome exchanges were significantly higher for the ATM- and NBS-deficient lines than for normal fibroblasts. However, in the NBS cells the linear dose-response term was significantly higher only for simple exchanges. The large increases in the quadratic dose-response terms in these repair-defective cell lines points the importance of the functions of ATM and NBS in chromatin modifications to facilitate correct DSB repair and minimize the formation of aberrations. The differences found between ATM- and NBS-deficient cells at low doses suggest that important questions should with regard to applying observations of radiation sensitivity at high dose to low-dose exposures. For aberrations induced by iron nuclei, regression models preferred purely linear dose responses for simple exchanges and quadratic dose responses for complex exchanges. Relative biological effectiveness (RBE) factors of all of

The Emerging Role of the Cytoskeleton in Chromosome Dynamics

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Maya Spichal

2017-05-01

Full Text Available Chromosomes underlie a dynamic organization that fulfills functional roles in processes like transcription, DNA repair, nuclear envelope stability, and cell division. Chromosome dynamics depend on chromosome structure and cannot freely diffuse. Furthermore, chromosomes interact closely with their surrounding nuclear environment, which further constrains chromosome dynamics. Recently, several studies enlighten that cytoskeletal proteins regulate dynamic chromosome organization. Cytoskeletal polymers that include actin filaments, microtubules and intermediate filaments can connect to the nuclear envelope via Linker of the Nucleoskeleton and Cytoskeleton (LINC complexes and transfer forces onto chromosomes inside the nucleus. Monomers of these cytoplasmic polymers and related proteins can also enter the nucleus and play different roles in the interior of the nucleus than they do in the cytoplasm. Nuclear cytoskeletal proteins can act as chromatin remodelers alone or in complexes with other nuclear proteins. They can also act as transcription factors. Many of these mechanisms have been conserved during evolution, indicating that the cytoskeletal regulation of chromosome dynamics is an essential process. In this review, we discuss the different influences of cytoskeletal proteins on chromosome dynamics by focusing on the well-studied model organism budding yeast.

Chromosomal characterization of the three subgenomes in the polyploids of Hordeum murinum L.: new insight into the evolution of this complex.

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Ángeles Cuadrado

Full Text Available Hordeum murinum L. is a species complex composed of related taxa, including the subspecies glaucum, murinum and leporinum. However, the phylogenetic relationships between the different taxa and their cytotypes, and the origin of the polyploid forms, remain points of controversy. The present work reports a comparative karyotype analysis of seven accessions of the H. murinum complex representing all subspecies and cytotypes. The karyotypes were determined by examining the distribution of the repetitive Triticeae DNA sequences pTa71, pTa794, pSc119.2, pAs1 and pHch950, the simple sequence repeats (SSRs (AG10, (AAC5, (AAG5, (ACT5, (ATC5, and (CCCTAAA3 via in situ hybridization. The chromosomes of the three subgenomes involved in the polyploids were identified. All tetraploids of all subspecies shared the same two subgenomes (thus suggesting them to in fact belong to the same taxon, the result of hybridization between two diploid ancestors. One of the subgenomes present in all tetraploids of all subspecies was found to be very similar (though not identical to the chromosome complement of the diploid glaucum. The hexaploid form of leporinum came about through a cross between a tetraploid and a third diploid form. Exclusively bivalent associations among homologous chromosomes were observed when analyzing pollen mother cells of tetraploid taxa. In conclusion, the present results identify all the individual chromosomes within the H. murinum complex, reveal its genome structure and phylogeny, and explain the appearance of the different cytotypes. Three cryptic species are proposed according to ploidy level that may deserve full taxonomic recognition.

Destabilized SMC5/6 complex leads to chromosome breakage syndrome with severe lung disease

NARCIS (Netherlands)

van der Crabben, Saskia N; Hennus, Marije P; McGregor, Grant A; Ritter, Deborah I; Nagamani, Sandesh C S; Wells, Owen S; Harakalova, Magdalena; Chinn, Ivan K; Alt, Aaron; Vondrova, Lucie; Hochstenbach, Ron; van Montfrans, Joris M; Terheggen-Lagro, Suzanne W; van Lieshout, Stef; van Roosmalen, Markus J; Renkens, Ivo; Duran, Karen; Nijman, Isaäc J.; Kloosterman, Wigard P; Hennekam, Eric; Orange, Jordan S; van Hasselt, Peter M; Wheeler, David A; Palecek, Jan J; Lehmann, Alan R; Oliver, Antony W; Pearl, Laurence H; Plon, Sharon E; Murray, Johanne M; van Haaften, Gijs

The structural maintenance of chromosomes (SMC) family of proteins supports mitotic proliferation, meiosis, and DNA repair to control genomic stability. Impairments in chromosome maintenance are linked to rare chromosome breakage disorders. Here, we have identified a chromosome breakage syndrome

Painting of fourth and chromosome-wide regulation of the 4th chromosome in Drosophila melanogaster.

Science.gov (United States)

Johansson, Anna-Mia; Stenberg, Per; Bernhardsson, Carolina; Larsson, Jan

2007-05-02

Drosophila melanogaster exhibits two expression-regulating systems that target whole, specific chromosomes: the dosage compensation system whereby the male-specific lethal complex doubles transcription of genes on the male X-chromosome and the chromosome 4-specific protein Painting of fourth, POF. POF is the first example of an autosome-specific protein and its presence raises the question of the universality of chromosome-specific regulation. Here we show that POF and heterochromatin protein 1 (HP1) are involved in the global regulation of the 4th chromosome. Contrary to previous conclusions, Pof is not essential for survival of diplo-4th karyotype flies. However, Pof is essential for survival of haplo-4th individuals and expression of chromosome 4 genes in diplo-4th individuals is decreased in the absence of Pof. Mapping of POF using chromatin immunoprecipitation suggested that it binds within genes. Furthermore, we show that POF binding is dependent on heterochromatin and that POF and HP1 bind interdependently to the 4th chromosome. We propose a balancing mechanism involving POF and HP1 that provides a feedback system for fine-tuning expression status of genes on the 4th chromosome.

Transposable elements in fish chromosomes: a study in the marine cobia species.

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Costa, G W W F; Cioffi, M B; Bertollo, L A C; Molina, W F

2013-01-01

Rachycentron canadum, a unique representative of the Rachycentridae family, has been the subject of considerable biotechnological interest due to its potential use in marine fish farming. This species has undergone extensive research concerning the location of genes and multigene families on its chromosomes. Although most of the genome of some organisms is composed of repeated DNA sequences, aspects of the origin and dispersion of these elements are still largely unknown. The physical mapping of repetitive sequences on the chromosomes of R. canadum proved to be relevant for evolutionary and applied purposes. Therefore, here, we present the mapping by fluorescence in situ hybridization of the transposable element (TE) Tol2, the non-LTR retrotransposons Rex1 and Rex3, together with the 18S and 5S rRNA genes in the chromosome of this species. The Tol2 TE, belonging to the family of hAT transposons, is homogeneously distributed in the euchromatic regions of the chromosomes but with huge colocalization with the 18S rDNA sites. The hybridization signals for Rex1 and Rex3 revealed a semi-arbitrary distribution pattern, presenting differentiated dispersion in euchromatic and heterochromatic regions. Rex1 elements are associated preferentially in heterochromatic regions, while Rex3 shows a scarce distribution in the euchromatic regions of the chromosomes. The colocalization of TEs with 18S and 5S rDNA revealed complex chromosomal regions of repetitive sequences. In addition, the nonpreferential distribution of Rex1 and Rex3 in all heterochromatic regions, as well as the preferential distribution of the Tol2 transposon associated with 18S rDNA sequences, reveals a distinct pattern of organization of TEs in the genome of this species. A heterogeneous chromosomal colonization of TEs may confer different evolutionary rates to the heterochromatic regions of this species.

Rapid molecular cytogenetic analysis of X-chromosomal microdeletions: Fluorescence in situ hybridization (FISH) for complex glycerol kinase deficiency

Energy Technology Data Exchange (ETDEWEB)

Worley, K.C.; Lindsay, E.A.; McCabe, E.R.B. [Baylor College of Medicine, Houston, TX (United States)] [and others

1995-07-17

Diagnosis of X-chromosomal microdeletions has relied upon the traditional methods of Southern blotting and DNA amplification, with carrier identification requiring time-consuming and unreliable dosage calculations. In this report, we describe rapid molecular cytogenetic identification of deleted DNA in affected males with the Xp21 contiguous gene syndrome (complex glycerol kinase deficiency, CGKD) and female carriers for this disorder. CGKD deletions involve the genes for glycerol kinase, Duchenne muscular dystrophy, and/or adrenal hypoplasia congenita. We report an improved method for diagnosis of deletions in individuals with CGKD and for identification of female carriers within their families using fluorescence in situ hybridization (FISH) with a cosmid marker (cosmid 35) within the glycerol kinase gene. When used in combination with an Xq control probe, affected males demonstrate a single signal from the control probe, while female carriers demonstrate a normal chromosome with two signals, as well as a deleted chromosome with a single signal from the control probe. FISH analysis for CGKD provides the advantages of speed and accuracy for evaluation of submicroscopic X-chromosome deletions, particularly in identification of female carriers. In addition to improving carrier evaluation, FISH will make prenatal diagnosis of CGKD more readily available. 17 refs., 2 figs.

Synaptonemal complex analysis of interracial hybrids between the Moscow and Neroosa chromosomal races of the common shrew Sorex araneus showing regular formation of a complex meiotic configuration (ring-of-four).

Science.gov (United States)

Matveevsky, Sergey N; Pavlova, Svetlana V; Maret M Acaeva; Oxana L Kolomiets

2012-01-01

Immunocytochemical and electron microscopic analysis of synaptonemal complexes (SCs) was carried out for the first time in homozygotes and complex Robertsonian heterozygotes (hybrids) of the common shrew, Sorex araneus Linnaeus, 1758, from a newly discovered hybrid zone between the Moscow and the Neroosa chromosomal races. These races differ in four monobrachial homologous metacentrics, and closed SC tetravalent is expected to be formed in meiosis of a hybrid. Indeed, such a multivalent was found at meiotic prophase I in hybrids. Interactions between multivalent and both autosomes and/or the sex chromosomes were observed. For the first time we have used immunocytochemical techniques to analyse asynapsis in Sorex araneus and show that the multivalent pairs in an orderly fashion with complete synapsis. Despite some signs of spermatocytes arrested in the meiotic prophase I, hybrids had large number of active sperm. Thus, Moscow - Neroosa hybrid males that form a ring-of-four meiotic configuration are most likely not sterile. Our results support previous demonstrations that monobrachial homology of metacentrics of the common shrew does not lead to complete reproductive isolation between parapatric chromosomal races of the species.

Synaptonemal complex analysis of interracial hybrids between the Moscow and Neroosa chromosomal races of the common shrew Sorex araneus showing regular formation of a complex meiotic configuration (ring-of-four

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Sergey Matveevsky

2012-09-01

Full Text Available Immunocytochemical and electron microscopic analysis of synaptonemal complexes (SCs was carried out for the first time in homozygotes and complex Robertsonian heterozygotes (hybrids of the common shrew, Sorex araneus Linnaeus, 1758, from a newly discovered hybrid zone between the Moscow and the Neroosa chromosomal races. These races differ in four monobrachial homologous metacentrics, and closed SC tetravalent is expected to be formed in meiosis of a hybrid. Indeed, such a multivalent was found at meiotic prophase I in hybrids. Interactions between multivalent and both autosomes and/or the sex chromosomes were observed. For the first time we have used immunocytochemical techniques to analyse asynapsis in S. araneus and show that the multivalent pairs in an orderly fashion with complete synapsis. Despite some signs of spermatocytes arrested in the meiotic prophase I, hybrids had large number of active sperm. Thus, Moscow – Neroosa hybrid males that form a ring-of-four meiotic configuration are most likely not sterile. Our results support previous demonstrations that monobrachial homology of metacentrics of the common shrew does not lead to complete reproductive isolation between parapatric chromosomal races of the species.

Chromosomal Mapping of Repetitive DNAs in the Grasshopper Abracris flavolineata Reveal Possible Ancestry of the B Chromosome and H3 Histone Spreading

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Bueno, Danilo; Palacios-Gimenez, Octavio Manuel; Cabral-de-Mello, Diogo Cavalcanti

2013-01-01

Supernumerary chromosomes (B chromosomes) occur in approximately 15% of eukaryote species. Although these chromosomes have been extensively studied, knowledge concerning their specific molecular composition is lacking in most cases. The accumulation of repetitive DNAs is one remarkable characteristic of B chromosomes, and the occurrence of distinct types of multigene families, satellite DNAs and some transposable elements have been reported. Here, we describe the organization of repetitive DNAs in the A complement and B chromosome system in the grasshopper species Abracris flavolineata using classical cytogenetic techniques and FISH analysis using probes for five multigene families, telomeric repeats and repetitive C0t-1 DNA fractions. The 18S rRNA and H3 histone multigene families are highly variable and well distributed in A. flavolineata chromosomes, which contrasts with the conservation of U snRNA genes and less variable distribution of 5S rDNA sequences. The H3 histone gene was an extensively distributed with clusters occurring in all chromosomes. Repetitive DNAs were concentrated in C-positive regions, including the pericentromeric region and small chromosomal arms, with some occurrence in C-negative regions, but abundance was low in the B chromosome. Finally, the first demonstration of the U2 snRNA gene in B chromosomes in A. flavolineata may shed light on its possible origin. These results provide new information regarding chromosomal variability for repetitive DNAs in grasshoppers and the specific molecular composition of B chromosomes. PMID:23826099

Different regions of the immunoglobulin heavy-chain locus are involved in chromosomal translocations in distinct pathogenic forms of Burkitt lymphoma

Energy Technology Data Exchange (ETDEWEB)

Neri, A.; Barriga, F.; Knowles, D.M.; Magrath, I.T.; Dalla-Favera, R.

1988-04-01

The authors show that endemic (eBL), sporadic (sBL), and acquired immunodeficiency syndrome-associated (AIDS-BL) forms of Burkitt lymphoma (BL) carrying t(8; 14) chromosomal translocations display different breakpoints within the immunoglobulin heavy-chain locus (IGH) on chromosome 14. In sBL (7 out of 11) and AIDS-BL (5 out of 6), the breakpoints occurred within or near the IGH ..mu.. switch (S/sub mu/) region on chromosome 14 and within the c-myc locus (MYC) on chromosome 8. In most eBL (13 out of 16) the breakpoints were mapped within or 5' to the IGH joining J/sub H/ region on chromosome 14 and outside the MYC locus on chromosome 8. Cloning and sequencing of the (8; 14) chromosomal junctions from two eBL cell lines and one eBL biopsy sample show that the recombination do not involve IGH-specific recombination signals on chromosome 14 or homologous sequences on chromosome 8, suggesting that these events are not likely to be mediated by the same mechanisms or enzymes as in IGH rearrangements. In general, these data have implications for the timing of occurrence of chromosomal translocations during B-cell differentiation in different BL types.

Hominoid chromosomal rearrangements on 17q map to complex regions of segmental duplication.

Science.gov (United States)

Cardone, Maria Francesca; Jiang, Zhaoshi; D'Addabbo, Pietro; Archidiacono, Nicoletta; Rocchi, Mariano; Eichler, Evan E; Ventura, Mario

2008-01-01

Chromosomal rearrangements, such as translocations and inversions, are recurrent phenomena during evolution, and both of them are involved in reproductive isolation and speciation. To better understand the molecular basis of chromosome rearrangements and their part in karyotype evolution, we have investigated the history of human chromosome 17 by comparative fluorescence in situ hybridization (FISH) and sequence analysis. Human bacterial artificial chromosome/p1 artificial chromosome probes spanning the length of chromosome 17 were used in FISH experiments on great apes, Old World monkeys and New World monkeys to study the evolutionary history of this chromosome. We observed that the macaque marker order represents the ancestral organization. Human, chimpanzee and gorilla homologous chromosomes differ by a paracentric inversion that occurred specifically in the Homo sapiens/Pan troglodytes/Gorilla gorilla ancestor. Detailed analyses of the paracentric inversion revealed that the breakpoints mapped to two regions syntenic to human 17q12/21 and 17q23, both rich in segmental duplications. Sequence analyses of the human and macaque organization suggest that the duplication events occurred in the catarrhine ancestor with the duplication blocks continuing to duplicate or undergo gene conversion during evolution of the hominoid lineage. We propose that the presence of these duplicons has mediated the inversion in the H. sapiens/P. troglodytes/G. gorilla ancestor. Recently, the same duplication blocks have been shown to be polymorphic in the human population and to be involved in triggering microdeletion and duplication in human. These results further support a model where genomic architecture has a direct role in both rearrangement involved in karyotype evolution and genomic instability in human.

Application of molecular cytogenetic techniques to clarify apparently balanced complex chromosomal rearrangements in two patients with an abnormal phenotype: Case report

NARCIS (Netherlands)

P.J.P. de Vree (Paula); M.E.H. Simon (Marleen); M.F. van Dooren (Marieke); G.H.T. Stoevelaar (Gerda); J.T.W. Hilkmann (José); M.A. Rongen (Michel); G.C.M. Huijbregts (Gido); A.J.H.M. Verkerk (Annemieke); P. Poddighe (Pino)

2009-01-01

textabstractBackground. Complex chromosomal rearrangements (CCR) are rare cytogenetic findings that are difficult to karyotype by conventional cytogenetic analysis partially because of the relative low resolution of this technique. High resolution genotyping is necessary in order to identify cryptic

Fission yeast strains with circular chromosomes require the 9-1-1 checkpoint complex for the viability in response to the anti-cancer drug 5-fluorodeoxyuridine.

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Hossain Mohammad Shamim

Full Text Available Thymidine kinase converts 5-fluorodeoxyuridine to 5-fluorodeoxyuridine monophosphate, which causes disruption of deoxynucleotide triphosphate ratios. The fission yeast Schizosaccharomyces pombe does not express endogenous thymidine kinase but 5-fluorodeoxyuridine inhibits growth when exogenous thymidine kinase is expressed. Unexpectedly, we found that 5-fluorodeoxyuridine causes S phase arrest even without thymidine kinase expression. DNA damage checkpoint proteins such as the 9-1-1 complex were required for viability in the presence of 5-fluorodeoxyuridine. We also found that strains with circular chromosomes, due to loss of pot1+, which have higher levels of replication stress, were more sensitive to loss of the 9-1-1 complex in the presence of 5-fluorodeoxyuridine. Thus, our results suggest that strains carrying circular chromosomes exhibit a greater dependence on DNA damage checkpoints to ensure viability in the presence of 5-fluorodeoxyuridine compared to stains that have linear chromosomes.

Fission yeast strains with circular chromosomes require the 9-1-1 checkpoint complex for the viability in response to the anti-cancer drug 5-fluorodeoxyuridine.

Science.gov (United States)

Shamim, Hossain Mohammad; Minami, Yukako; Tanaka, Daiki; Ukimori, Shinobu; Murray, Johanne M; Ueno, Masaru

2017-01-01

Thymidine kinase converts 5-fluorodeoxyuridine to 5-fluorodeoxyuridine monophosphate, which causes disruption of deoxynucleotide triphosphate ratios. The fission yeast Schizosaccharomyces pombe does not express endogenous thymidine kinase but 5-fluorodeoxyuridine inhibits growth when exogenous thymidine kinase is expressed. Unexpectedly, we found that 5-fluorodeoxyuridine causes S phase arrest even without thymidine kinase expression. DNA damage checkpoint proteins such as the 9-1-1 complex were required for viability in the presence of 5-fluorodeoxyuridine. We also found that strains with circular chromosomes, due to loss of pot1+, which have higher levels of replication stress, were more sensitive to loss of the 9-1-1 complex in the presence of 5-fluorodeoxyuridine. Thus, our results suggest that strains carrying circular chromosomes exhibit a greater dependence on DNA damage checkpoints to ensure viability in the presence of 5-fluorodeoxyuridine compared to stains that have linear chromosomes.

Meiotic recombination analyses of individual chromosomes in male domestic pigs (Sus scrofa domestica.

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Nicolas Mary

Full Text Available For the first time in the domestic pig, meiotic recombination along the 18 porcine autosomes was directly studied by immunolocalization of MLH1 protein. In total, 7,848 synaptonemal complexes from 436 spermatocytes were analyzed, and 13,969 recombination sites were mapped. Individual chromosomes for 113 of the 436 cells (representing 2,034 synaptonemal complexes were identified by immunostaining and fluorescence in situ hybridization (FISH. The average total length of autosomal synaptonemal complexes per cell was 190.3 µm, with 32.0 recombination sites (crossovers, on average, per cell. The number of crossovers and the lengths of the autosomal synaptonemal complexes showed significant intra- (i.e. between cells and inter-individual variations. The distributions of recombination sites within each chromosomal category were similar: crossovers in metacentric and submetacentric chromosomes were concentrated in the telomeric regions of the p- and q-arms, whereas two hotspots were located near the centromere and in the telomeric region of acrocentrics. Lack of MLH1 foci was mainly observed in the smaller chromosomes, particularly chromosome 18 (SSC18 and the sex chromosomes. All autosomes displayed positive interference, with a large variability between the chromosomes.

BAC-FISH assays delineate complex chromosomal rearrangements in a case of post-Chernobyl childhood thyroid cancer.

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Horst F Zitzelsberger

2009-12-01

Full Text Available Structural chromosome aberrations are known hallmarks of many solid tumors. In the papillary form of thyroid cancer (PTC, for example, activation of the receptor tyrosine kinase (RTK genes, RET and neurotrophic tyrosine kinase receptor type I (NTRK1 by intra- and interchromosomal rearrangements has been suggested as a cause of the disease. However, many phenotypically similar tumors do not carry an activated RET or NTRK-1 gene or express abnormal ret or NTRK-1 transcripts. Thus, we hypothesize that other cellular RTK-type genes are aberrantly expressed in these tumors. Using fluorescence in situ hybridization-based methods, we are studying karyotype changes in a relatively rare subgroup of PTCs, i.e., tumors that arose in children following the 1986 nuclear accident in Chernobyl, Ukraine. Here, we report our technical developments and progress in deciphering complex chromosome aberrations in case S48TK, an aggressively growing PTC cell line, which shows an unusual high number of unbalanced translocations.

BAC-FISH assays delineate complex chromosomal rearrangements in a case of post-Chernobyl childhood thyroid cancer

Energy Technology Data Exchange (ETDEWEB)

Kwan, Johnson; Baumgartner, Adolf; Lu, Chun-Mei; Wang, Mei; Weier, Jingly F.; Zitzelsberger, Horst F.; Weier, Heinz-Ulrich G.

2009-03-09

Structural chromosome aberrations are known hallmarks of many solid tumors. In the papillary form of thyroid cancer (PTC), for example, activation of the receptor tyrosine kinase (RTK) genes, RET and neurotrophic tyrosine kinase receptor type I (NTRK1) by intra- and interchromosomal rearrangements has been suggested as a cause of the disease. However, many phenotypically similar tumors do not carry an activated RET or NTRK-1 gene or express abnormal ret or NTRK-1 transcripts. Thus, we hypothesize that other cellular RTK-type genes are aberrantly expressed in these tumors. Using fluorescence in situ hybridization-based methods, we are studying karyotype changes in a relatively rare subgroup of PTCs, i.e., tumors that arose in children following the 1986 nuclear accident in Chernobyl, Ukraine. Here, we report our technical developments and progress in deciphering complex chromosome aberrations in case S48TK, an aggressively growing PTC cell line, which shows an unusual high number of unbalanced translocations.

Chromosomal organization of adrenergic receptor genes

International Nuclear Information System (INIS)

Yang-Feng, T.L.; Xue, Feiyu; Zhong, Wuwei; Cotecchia, S.; Frielle, T.; Caron, M.G.; Lefkowitz, R.J.; Francke, U.

1990-01-01

The adrenergic receptors (ARs) (subtypes α 1 , α 2 , β 1 , and β 2 ) are a prototypic family of guanine nucleotide binding regulatory protein-coupled receptors that mediate the physiological effects of the hormone epinephrine and the neurotransmitter norepinephrine. The authors have previously assigned the genes for β 2 -and α 2 -AR to human chromosomes 5 and 10, respectively. By Southern analysis of somatic cell hybrids and in situ chromosomal hybridization, they have now mapped the α 1 -AR gene to chromosome 5q32→q34, the same position as β 2 -AR, and the β 1 -AR gene to chromosome 10q24→q26, the region where α 2 -AR, is located. In mouse, both α 2 -and β 1 -AR genes were assigned to chromosome 19, and the α 1 -AR locus was localized to chromosome 11. Pulsed field gel electrophoresis has shown that the α 1 -and β 2 -AR genes in humans are within 300 kilobases (kb) and the distance between the α 2 - and β 1 -AR genes is <225 kb. The proximity of these two pairs of AR genes and the sequence similarity that exists among all the ARs strongly suggest that they are evolutionarily related. Moreover, they likely arose from a common ancestral receptor gene and subsequently diverged through gene duplication and chromosomal duplication to perform their distinctive roles in mediation the physiological effects of catecholamines. The AR genes thus provide a paradigm for understanding the evolution of such structurally conserved yet functionally divergent families off receptor molecules

The Mini-Chromosome Maintenance (Mcm) Complexes Interact with DNA Polymerase α-Primase and Stimulate Its Ability to Synthesize RNA Primers

Science.gov (United States)

You, Zhiying; De Falco, Mariarosaria; Kamada, Katsuhiko; Pisani, Francesca M.; Masai, Hisao

2013-01-01

The Mini-chromosome maintenance (Mcm) proteins are essential as central components for the DNA unwinding machinery during eukaryotic DNA replication. DNA primase activity is required at the DNA replication fork to synthesize short RNA primers for DNA chain elongation on the lagging strand. Although direct physical and functional interactions between helicase and primase have been known in many prokaryotic and viral systems, potential interactions between helicase and primase have not been explored in eukaryotes. Using purified Mcm and DNA primase complexes, a direct physical interaction is detected in pull-down assays between the Mcm2∼7 complex and the hetero-dimeric DNA primase composed of the p48 and p58 subunits. The Mcm4/6/7 complex co-sediments with the primase and the DNA polymerase α-primase complex in glycerol gradient centrifugation and forms a Mcm4/6/7-primase-DNA ternary complex in gel-shift assays. Both the Mcm4/6/7 and Mcm2∼7 complexes stimulate RNA primer synthesis by DNA primase in vitro. However, primase inhibits the Mcm4/6/7 helicase activity and this inhibition is abolished by the addition of competitor DNA. In contrast, the ATP hydrolysis activity of Mcm4/6/7 complex is not affected by primase. Mcm and primase proteins mutually stimulate their DNA-binding activities. Our findings indicate that a direct physical interaction between primase and Mcm proteins may facilitate priming reaction by the former protein, suggesting that efficient DNA synthesis through helicase-primase interactions may be conserved in eukaryotic chromosomes. PMID:23977294

The mini-chromosome maintenance (Mcm complexes interact with DNA polymerase α-primase and stimulate its ability to synthesize RNA primers.

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Zhiying You

Full Text Available The Mini-chromosome maintenance (Mcm proteins are essential as central components for the DNA unwinding machinery during eukaryotic DNA replication. DNA primase activity is required at the DNA replication fork to synthesize short RNA primers for DNA chain elongation on the lagging strand. Although direct physical and functional interactions between helicase and primase have been known in many prokaryotic and viral systems, potential interactions between helicase and primase have not been explored in eukaryotes. Using purified Mcm and DNA primase complexes, a direct physical interaction is detected in pull-down assays between the Mcm2~7 complex and the hetero-dimeric DNA primase composed of the p48 and p58 subunits. The Mcm4/6/7 complex co-sediments with the primase and the DNA polymerase α-primase complex in glycerol gradient centrifugation and forms a Mcm4/6/7-primase-DNA ternary complex in gel-shift assays. Both the Mcm4/6/7 and Mcm2~7 complexes stimulate RNA primer synthesis by DNA primase in vitro. However, primase inhibits the Mcm4/6/7 helicase activity and this inhibition is abolished by the addition of competitor DNA. In contrast, the ATP hydrolysis activity of Mcm4/6/7 complex is not affected by primase. Mcm and primase proteins mutually stimulate their DNA-binding activities. Our findings indicate that a direct physical interaction between primase and Mcm proteins may facilitate priming reaction by the former protein, suggesting that efficient DNA synthesis through helicase-primase interactions may be conserved in eukaryotic chromosomes.

Chromosome Synapsis and Recombination in Male Hybrids between Two Chromosome Races of the Common Shrew (Sorex araneus L., Soricidae, Eulipotyphla

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Nadezhda M. Belonogova

2017-10-01

Full Text Available Hybrid zones between chromosome races of the common shrew (Sorex araneus provide exceptional models to study the potential role of chromosome rearrangements in the initial steps of speciation. The Novosibirsk and Tomsk races differ by a series of Robertsonian fusions with monobrachial homology. They form a narrow hybrid zone and generate hybrids with both simple (chain of three chromosomes and complex (chain of eight or nine synaptic configurations. Using immunolocalisation of the meiotic proteins, we examined chromosome pairing and recombination in males from the hybrid zone. Homozygotes and simple heterozygotes for Robertsonian fusions showed a low frequency of synaptic aberrations (<10%. The carriers of complex synaptic configurations showed multiple pairing abnormalities, which might lead to reduced fertility. The recombination frequency in the proximal regions of most chromosomes of all karyotypes was much lower than in the other regions. The strong suppression of recombination in the pericentromeric regions and co-segregation of race specific chromosomes involved in the long chains would be expected to lead to linkage disequilibrium between genes located there. Genic differentiation, together with the high frequency of pairing aberrations in male carriers of the long chains, might contribute to maintenance of the narrow hybrid zone.

To Break or Not To Break: Sex Chromosome Hemizygosity During Meiosis in Caenorhabditis.

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

2016-11-01

Meiotic recombination establishes connections between homologous chromosomes to promote segregation. Hemizygous regions of sex chromosomes have no homologous chromosome to recombine with, yet must be transmitted through meiosis. An extreme case of hemizygosity exists in the genus Caenorhabditis, where males have a single X chromosome that completely lacks a homologous partner. To determine whether similar strategies have evolved to accommodate hemizygosity of the X during male meiosis in Caenorhabditis with distinct modes of sexual reproduction, we examined induction and processing of meiotic double strand breaks (DSBs) in androdioecious (hermaphrodite/male) Caenorhabditis elegans and C. briggsae, and gonochoristic (female/male) C. remanei and C. brenneri Analysis of the recombinase RAD-51 suggests more meiotic DSBs are induced in gonochoristic vs. androdioecious species. However, in late prophase in all species, chromosome pairs are restructured into bivalents around a single axis, suggesting that the holocentric nature of Caenorhabditis chromosomes dictates a single crossover per bivalent regardless of the number of DSBs induced. Interestingly, RAD-51 foci were readily observed on the X chromosome of androdioecious male germ cells, while very few were detected in gonochoristic male germ cells. As in C. elegans, the X chromosome in C. briggsae male germ cells undergoes transient pseudosynapsis and flexibility in DSB repair pathway choice. In contrast, in C. remanei and C. brenneri male germ cells, the X chromosome does not undergo pseudosynapsis and appears refractory to SPO-11-induced breaks. Together our results suggest that distinct strategies have evolved to accommodate sex chromosome hemizygosity during meiosis in closely related Caenorhabditis species. Copyright © 2016 by the Genetics Society of America.

Structure of the human chromosome interaction network.

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Sergio Sarnataro

Full Text Available New Hi-C technologies have revealed that chromosomes have a complex network of spatial contacts in the cell nucleus of higher organisms, whose organisation is only partially understood. Here, we investigate the structure of such a network in human GM12878 cells, to derive a large scale picture of nuclear architecture. We find that the intensity of intra-chromosomal interactions is power-law distributed. Inter-chromosomal interactions are two orders of magnitude weaker and exponentially distributed, yet they are not randomly arranged along the genomic sequence. Intra-chromosomal contacts broadly occur between epigenomically homologous regions, whereas inter-chromosomal contacts are especially associated with regions rich in highly expressed genes. Overall, genomic contacts in the nucleus appear to be structured as a network of networks where a set of strongly individual chromosomal units, as envisaged in the 'chromosomal territory' scenario derived from microscopy, interact with each other via on average weaker, yet far from random and functionally important interactions.

Distinct genetic alterations in colorectal cancer.

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Hassan Ashktorab

Full Text Available BACKGROUND: Colon cancer (CRC development often includes chromosomal instability (CIN leading to amplifications and deletions of large DNA segments. Epidemiological, clinical, and cytogenetic studies showed that there are considerable differences between CRC tumors from African Americans (AAs and Caucasian patients. In this study, we determined genomic copy number aberrations in sporadic CRC tumors from AAs, in order to investigate possible explanations for the observed disparities. METHODOLOGY/PRINCIPAL FINDINGS: We applied genome-wide array comparative genome hybridization (aCGH using a 105k chip to identify copy number aberrations in samples from 15 AAs. In addition, we did a population comparative analysis with aCGH data in Caucasians as well as with a widely publicized list of colon cancer genes (CAN genes. There was an average of 20 aberrations per patient with more amplifications than deletions. Analysis of DNA copy number of frequently altered chromosomes revealed that deletions occurred primarily in chromosomes 4, 8 and 18. Chromosomal duplications occurred in more than 50% of cases on chromosomes 7, 8, 13, 20 and X. The CIN profile showed some differences when compared to Caucasian alterations. CONCLUSIONS/SIGNIFICANCE: Chromosome X amplification in male patients and chromosomes 4, 8 and 18 deletions were prominent aberrations in AAs. Some CAN genes were altered at high frequencies in AAs with EXOC4, EPHB6, GNAS, MLL3 and TBX22 as the most frequently deleted genes and HAPLN1, ADAM29, SMAD2 and SMAD4 as the most frequently amplified genes. The observed CIN may play a distinctive role in CRC in AAs.

Chromosomal organization and segregation in Pseudomonas aeruginosa.

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Isabelle Vallet-Gely

2013-05-01

Full Text Available The study of chromosomal organization and segregation in a handful of bacteria has revealed surprising variety in the mechanisms mediating such fundamental processes. In this study, we further emphasized this diversity by revealing an original organization of the Pseudomonas aeruginosa chromosome. We analyzed the localization of 20 chromosomal markers and several components of the replication machinery in this important opportunistic γ-proteobacteria pathogen. This technique allowed us to show that the 6.3 Mb unique circular chromosome of P. aeruginosa is globally oriented from the old pole of the cell to the division plane/new pole along the oriC-dif axis. The replication machinery is positioned at mid-cell, and the chromosomal loci from oriC to dif are moved sequentially to mid-cell prior to replication. The two chromosomal copies are subsequently segregated at their final subcellular destination in the two halves of the cell. We identified two regions in which markers localize at similar positions, suggesting a bias in the distribution of chromosomal regions in the cell. The first region encompasses 1.4 Mb surrounding oriC, where loci are positioned around the 0.2/0.8 relative cell length upon segregation. The second region contains at least 800 kb surrounding dif, where loci show an extensive colocalization step following replication. We also showed that disrupting the ParABS system is very detrimental in P. aeruginosa. Possible mechanisms responsible for the coordinated chromosomal segregation process and for the presence of large distinctive regions are discussed.

Direct kinetochore-spindle pole connections are not required for chromosome segregation.

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Sikirzhytski, Vitali; Magidson, Valentin; Steinman, Jonathan B; He, Jie; Le Berre, Maël; Tikhonenko, Irina; Ault, Jeffrey G; McEwen, Bruce F; Chen, James K; Sui, Haixin; Piel, Matthieu; Kapoor, Tarun M; Khodjakov, Alexey

2014-07-21

Segregation of genetic material occurs when chromosomes move to opposite spindle poles during mitosis. This movement depends on K-fibers, specialized microtubule (MT) bundles attached to the chromosomes' kinetochores. A long-standing assumption is that continuous K-fibers connect every kinetochore to a spindle pole and the force for chromosome movement is produced at the kinetochore and coupled with MT depolymerization. However, we found that chromosomes still maintained their position at the spindle equator during metaphase and segregated properly during anaphase when one of their K-fibers was severed near the kinetochore with a laser microbeam. We also found that, in normal fully assembled spindles, K-fibers of some chromosomes did not extend to the spindle pole. These K-fibers connected to adjacent K-fibers and/or nonkinetochore MTs. Poleward movement of chromosomes with short K-fibers was uncoupled from MT depolymerization at the kinetochore. Instead, these chromosomes moved by dynein-mediated transport of the entire K-fiber/kinetochore assembly. Thus, at least two distinct parallel mechanisms drive chromosome segregation in mammalian cells.

X chromosome dosage compensation via enhanced transcriptional elongation in Drosophila.

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Larschan, Erica; Bishop, Eric P; Kharchenko, Peter V; Core, Leighton J; Lis, John T; Park, Peter J; Kuroda, Mitzi I

2011-03-03

The evolution of sex chromosomes has resulted in numerous species in which females inherit two X chromosomes but males have a single X, thus requiring dosage compensation. MSL (Male-specific lethal) complex increases transcription on the single X chromosome of Drosophila males to equalize expression of X-linked genes between the sexes. The biochemical mechanisms used for dosage compensation must function over a wide dynamic range of transcription levels and differential expression patterns. It has been proposed that the MSL complex regulates transcriptional elongation to control dosage compensation, a model subsequently supported by mapping of the MSL complex and MSL-dependent histone 4 lysine 16 acetylation to the bodies of X-linked genes in males, with a bias towards 3' ends. However, experimental analysis of MSL function at the mechanistic level has been challenging owing to the small magnitude of the chromosome-wide effect and the lack of an in vitro system for biochemical analysis. Here we use global run-on sequencing (GRO-seq) to examine the specific effect of the MSL complex on RNA Polymerase II (RNAP II) on a genome-wide level. Results indicate that the MSL complex enhances transcription by facilitating the progression of RNAP II across the bodies of active X-linked genes. Improving transcriptional output downstream of typical gene-specific controls may explain how dosage compensation can be imposed on the diverse set of genes along an entire chromosome.

A sexy spin on nonrandom chromosome segregation.

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Charville, Gregory W; Rando, Thomas A

2013-06-06

Nonrandom chromosome segregation is an intriguing phenomenon linked to certain asymmetric stem cell divisions. In a recent report in Nature, Yadlapalli and Yamashita (2013) observe nonrandom segregation of X and Y chromosomes in Drosophila germline stem cells and shed light on the complex mechanisms of this fascinating process. Copyright © 2013 Elsevier Inc. All rights reserved.

High degree of sex chromosome differentiation in stickleback fishes

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Shimada Yukinori

2011-09-01

Full Text Available Abstract Background Studies of closely related species with different sex chromosome systems can provide insights into the processes of sex chromosome differentiation and evolution. To investigate the potential utility of molecular markers in studying sex chromosome differentiation at early stages of their divergence, we examined the levels and patterns of genetic differentiation between sex chromosomes in nine-spined (Pungitius pungitius and three-spined sticklebacks (Gasterosteus aculeatus using microsatellite markers. Results A set of novel microsatellite markers spanning the entire length of the sex chromosomes were developed for nine-spined sticklebacks using the sequenced genomes of other fish species. Sex-specific patterns of genetic variability and male-specific alleles were identified at most of these loci, indicating a high degree of differentiation between the X and Y chromosomes in nine-spined sticklebacks. In three-spined sticklebacks, male-specific alleles were detected at some loci confined to two chromosomal regions. In addition, male-specific null alleles were identified at several other loci, implying the absence of Y chromosomal alleles at these loci. Overall, male-specific alleles and null alleles were found over a region spanning 81% of the sex chromosomes in three-spined sticklebacks. Conclusions High levels but distinct patterns of sex chromosome differentiation were uncovered in the stickleback species that diverged 13 million years ago. Our results suggest that the Y chromosome is highly degenerate in three-spined sticklebacks, but not in nine-spined sticklebacks. In general, the results demonstrate that microsatellites can be useful in identifying the degree and patterns of sex chromosome differentiation in species at initial stages of sex chromosome evolution.

Chromosomal rearrangements in Tourette syndrome

DEFF Research Database (Denmark)

Bertelsen, Birgitte; Debes, Nanette Mol; Hjermind, Lena E

2013-01-01

, and identification of susceptibility genes through linkage and association studies has been complicated due to inherent difficulties such as no clear mode of inheritance, genetic heterogeneity, and apparently incomplete penetrance. Positional cloning through mapping of disease-related chromosome rearrangements has...... been an efficient tool for the cloning of disease genes in several Mendelian disorders and in a number of complex disorders. Through cytogenetic investigation of 205 TS patients, we identified three possibly disease-associated chromosome rearrangements rendering this approach relevant in chasing TS...

Six-Coordinate Ln(III Complexes with Various Coordination Geometries Showing Distinct Magnetic Properties

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Mei Guo

2018-01-01

Full Text Available The syntheses, structural characterization, and magnetic properties of three lanthanide complexes with formulas [Ln(L13] (Ln = Dy (1Dy; Er (1Er; and [Dy(L22] (2Dy were reported. Complexes 1Dy and 1Er are isostructural with the metal ion in distorted trigonal-prismatic coordination geometry, but exhibit distinct magnetic properties due to the different shapes of electron density for DyIII (oblate and ErIII (prolate ions. Complex 1Dy shows obvious SMM behavior under a zero direct current (dc field with an effective energy barrier of 31.4 K, while complex 1Er only features SMM behavior under a 400 Oe external field with an effective energy barrier of 23.96 K. In stark contrast, complex 2Dy with the octahedral geometry only exhibits the frequency dependence of alternating current (ac susceptibility signals without χ″ peaks under a zero dc field.

Diagnostic radiation and chromosome aberrations

International Nuclear Information System (INIS)

Patil, S.R.; Hecht, F.; Lubs, H.A.; Kimberling, W.; Brown, J.; Gerald, P.S.; Summitt, R.L.

1977-01-01

Some evidence is presented suggesting that diagnostic X-rays may be important in the origin of a new chromosomal abnormality other than Down syndrome. Chromosome analyses have been carried out on 4342 children, seven or eight years old. Maternal diagnostic irradiation in the year before conception and up to third lunar month of the index pregnancy was recorded, before the chromosome study began, together with a large amount of family and clinical data. Information on X-ray exposure was supplied by the mothers, s o radiation dosage could not be estimated. 21 children (including a pair of twins and a pair of siblings) born to 19 mothers had chromosomal aberrations. The mothers of six children with inherited translocations, rearrangements and XYY karyotypes were excluded, and 3 (23%) of the remaining 13 mothers had received abdominal and pelvic X-ray exposures. In the whole sample, however, only 6% of the mothers had diagnostic irradiation. Two of these mothers, aged sixteen and twenty, gave birth to a child each with de-novo autosomal translocations, and the third mother, aged thirty-two, had a child with a complex mosaicism involving one X chromosome. Although the sample size of the mothers with chromosomally abnormal children is small, the results are significant. (U.K.)

Diagnostic radiation and chromosome aberrations

Energy Technology Data Exchange (ETDEWEB)

Patil, S R; Hecht, F [Dept. of Pediatrics, Child Development and Rehabilitation Center, Univ. of Oregon Health Sciences Center, Portland, Oregon (USA); Lubs, H A; Kimberling, W; Brown, J; Gerald, P S; Summitt, R L

1977-01-15

Some evidence is presented suggesting that diagnostic X-rays may be important in the origin of a new chromosomal abnormality other than Down syndrome. Chromosome analyses have been carried out on 4342 children, seven or eight years old. Maternal diagnostic irradiation in the year before conception and up to third lunar month of the index pregnancy was recorded, before the chromosome study began, together with a large amount of family and clinical data. Information on X-ray exposure was supplied by the mothers, so radiation dosage could not be estimated. 21 children (including a pair of twins and a pair of siblings) born to 19 mothers had chromosomal aberrations. The mothers of six children with inherited translocations, rearrangements and XYY karyotypes were excluded, and 3 (23%) of the remaining 13 mothers had received abdominal and pelvic X-ray exposures. In the whole sample, however, only 6% of the mothers had diagnostic irradiation. Two of these mothers, aged sixteen and twenty, gave birth to a child each with de-novo autosomal translocations, and the third mother, aged thirty-two, had a child with a complex mosaicism involving one X chromosome. Although the sample size of the mothers with chromosomally abnormal children is small, the results are significant.

Chromosomal abnormality in patients with secondary amenorrhea.

Science.gov (United States)

Safai, Akbar; Vasei, Mohammad; Attaranzadeh, Armin; Azad, Fariborz; Tabibi, Narjes

2012-04-01

Secondary amenorrhea is a condition in which there is cessation of menses after at least one menstruation. It is a symptom of different diseases, such as hormonal disturbances which range from pituitary to ovarian origin, as well as chromosomal abnormalities. Knowledge of the distinct cause of secondary amenorrhea is of tremendous benefit for the management and monitoring of patients. In this study, we determine the chromosomal abnormalities in patients with secondary amenorrhea in Southwest Iran. We selected 94 patients with secondary amenorrhea who referred to our Cytogenetic Ward from 2004 until 2009. For karyotyping, peripheral blood lymphocyte cultures were set up by conventional technique. In this study, 5.3% (n=5) of patients with secondary amenorrhea presented with chromosomal abnormalities, of which all contained an X element. The chromosomal abnormalities were: i) 45, X (n=1); ii) 47, XXX (n=1); iii) 45, X [13]/ 45, Xi(X)q[17] (n=1);  iv) 45, X[12]/46,X,+mar[12] (n=1); and v) 46,X,del(Xq)(q23q28) (n=1). Our study revealed that some causes of secondary amenorrhea could be due to chromosomal abnormalities. Therefore, cytogenetic studies should be important tests in the evaluation of patients with secondary amenorrhea.

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...

Direct kinetochore–spindle pole connections are not required for chromosome segregation

Science.gov (United States)

Sikirzhytski, Vitali; Magidson, Valentin; Steinman, Jonathan B.; He, Jie; Le Berre, Maël; Tikhonenko, Irina; Ault, Jeffrey G.; McEwen, Bruce F.; Chen, James K.; Sui, Haixin; Piel, Matthieu; Kapoor, Tarun M.

2014-01-01

Segregation of genetic material occurs when chromosomes move to opposite spindle poles during mitosis. This movement depends on K-fibers, specialized microtubule (MT) bundles attached to the chromosomes′ kinetochores. A long-standing assumption is that continuous K-fibers connect every kinetochore to a spindle pole and the force for chromosome movement is produced at the kinetochore and coupled with MT depolymerization. However, we found that chromosomes still maintained their position at the spindle equator during metaphase and segregated properly during anaphase when one of their K-fibers was severed near the kinetochore with a laser microbeam. We also found that, in normal fully assembled spindles, K-fibers of some chromosomes did not extend to the spindle pole. These K-fibers connected to adjacent K-fibers and/or nonkinetochore MTs. Poleward movement of chromosomes with short K-fibers was uncoupled from MT depolymerization at the kinetochore. Instead, these chromosomes moved by dynein-mediated transport of the entire K-fiber/kinetochore assembly. Thus, at least two distinct parallel mechanisms drive chromosome segregation in mammalian cells. PMID:25023516

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

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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.

Looking for Broken TAD Boundaries and Changes on DNA Interactions: Clinical Guide to 3D Chromatin Change Analysis in Complex Chromosomal Rearrangements and Chromothripsis.

Science.gov (United States)

Yauy, Kevin; Gatinois, Vincent; Guignard, Thomas; Sati, Satish; Puechberty, Jacques; Gaillard, Jean Baptiste; Schneider, Anouck; Pellestor, Franck

2018-01-01

Apparition of next-generation sequencing (NGS) was a breakthrough on knowledge of genome structure. Bioinformatic tools are a key point to analyze this huge amount of data from NGS and characterize the three-dimensional organization of chromosomes. This chapter describes usage of different browsers to explore publicly available online data and to search for possible 3D chromatin changes involved during complex chromosomal rearrangements as chromothripsis. Their pathogenic impact on clinical phenotype and gene misexpression can also be evaluated with annotated databases.

Social chromosome variants differentially affect queen determination and the survival of workers in the fire ant Solenopsis invicta.

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Buechel, Séverine D; Wurm, Yanick; Keller, Laurent

2014-10-01

Intraspecific variation in social organization is common, yet the underlying causes are rarely known. An exception is the fire ant Solenopsis invicta in which the existence of two distinct forms of social colony organization is under the control of the two variants of a pair of social chromosomes, SB and Sb. Colonies containing exclusively SB/SB workers accept only one single queen and she must be SB/SB. By contrast, when colonies contain more than 10% of SB/Sb workers, they accept several queens but only SB/Sb queens. The variants of the social chromosome are associated with several additional important phenotypic differences, including the size, fecundity and dispersal strategies of queens, aggressiveness of workers, and sperm count in males. However, little is known about whether social chromosome variants affect fitness in other life stages. Here, we perform experiments to determine whether differential selection occurs during development and in adult workers. We find evidence that the Sb variant of the social chromosome increases the likelihood of female brood to develop into queens and that adult SB/Sb workers, the workers that cull SB/SB queens, are overrepresented in comparison to SB/SB workers. This demonstrates that supergenes such as the social chromosome can have complex effects on phenotypes at various stages of development. © 2014 John Wiley & Sons Ltd.

A physical map of Brassica oleracea shows complexity of chromosomal changes following recursive paleopolyploidizations

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Giattina Emily

2011-09-01

Full Text Available Abstract Background Evolution of the Brassica species has been recursively affected by polyploidy events, and comparison to their relative, Arabidopsis thaliana, provides means to explore their genomic complexity. Results A genome-wide physical map of a rapid-cycling strain of B. oleracea was constructed by integrating high-information-content fingerprinting (HICF of Bacterial Artificial Chromosome (BAC clones with hybridization to sequence-tagged probes. Using 2907 contigs of two or more BACs, we performed several lines of comparative genomic analysis. Interspecific DNA synteny is much better preserved in euchromatin than heterochromatin, showing the qualitative difference in evolution of these respective genomic domains. About 67% of contigs can be aligned to the Arabidopsis genome, with 96.5% corresponding to euchromatic regions, and 3.5% (shown to contain repetitive sequences to pericentromeric regions. Overgo probe hybridization data showed that contigs aligned to Arabidopsis euchromatin contain ~80% of low-copy-number genes, while genes with high copy number are much more frequently associated with pericentromeric regions. We identified 39 interchromosomal breakpoints during the diversification of B. oleracea and Arabidopsis thaliana, a relatively high level of genomic change since their divergence. Comparison of the B. oleracea physical map with Arabidopsis and other available eudicot genomes showed appreciable 'shadowing' produced by more ancient polyploidies, resulting in a web of relatedness among contigs which increased genomic complexity. Conclusions A high-resolution genetically-anchored physical map sheds light on Brassica genome organization and advances positional cloning of specific genes, and may help to validate genome sequence assembly and alignment to chromosomes. All the physical mapping data is freely shared at a WebFPC site (http://lulu.pgml.uga.edu/fpc/WebAGCoL/brassica/WebFPC/; Temporarily password-protected: account

A physical map of Brassica oleracea shows complexity of chromosomal changes following recursive paleopolyploidizations

Science.gov (United States)

2011-01-01

Background Evolution of the Brassica species has been recursively affected by polyploidy events, and comparison to their relative, Arabidopsis thaliana, provides means to explore their genomic complexity. Results A genome-wide physical map of a rapid-cycling strain of B. oleracea was constructed by integrating high-information-content fingerprinting (HICF) of Bacterial Artificial Chromosome (BAC) clones with hybridization to sequence-tagged probes. Using 2907 contigs of two or more BACs, we performed several lines of comparative genomic analysis. Interspecific DNA synteny is much better preserved in euchromatin than heterochromatin, showing the qualitative difference in evolution of these respective genomic domains. About 67% of contigs can be aligned to the Arabidopsis genome, with 96.5% corresponding to euchromatic regions, and 3.5% (shown to contain repetitive sequences) to pericentromeric regions. Overgo probe hybridization data showed that contigs aligned to Arabidopsis euchromatin contain ~80% of low-copy-number genes, while genes with high copy number are much more frequently associated with pericentromeric regions. We identified 39 interchromosomal breakpoints during the diversification of B. oleracea and Arabidopsis thaliana, a relatively high level of genomic change since their divergence. Comparison of the B. oleracea physical map with Arabidopsis and other available eudicot genomes showed appreciable 'shadowing' produced by more ancient polyploidies, resulting in a web of relatedness among contigs which increased genomic complexity. Conclusions A high-resolution genetically-anchored physical map sheds light on Brassica genome organization and advances positional cloning of specific genes, and may help to validate genome sequence assembly and alignment to chromosomes. All the physical mapping data is freely shared at a WebFPC site (http://lulu.pgml.uga.edu/fpc/WebAGCoL/brassica/WebFPC/; Temporarily password-protected: account: pgml; password: 123qwe123

Neocentromeres Provide Chromosome Segregation Accuracy and Centromere Clustering to Multiple Loci along a Candida albicans Chromosome.

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Laura S Burrack

2016-09-01

Full Text Available Assembly of kinetochore complexes, involving greater than one hundred proteins, is essential for chromosome segregation and genome stability. Neocentromeres, or new centromeres, occur when kinetochores assemble de novo, at DNA loci not previously associated with kinetochore proteins, and they restore chromosome segregation to chromosomes lacking a functional centromere. Neocentromeres have been observed in a number of diseases and may play an evolutionary role in adaptation or speciation. However, the consequences of neocentromere formation on chromosome missegregation rates, gene expression, and three-dimensional (3D nuclear structure are not well understood. Here, we used Candida albicans, an organism with small, epigenetically-inherited centromeres, as a model system to study the functions of twenty different neocentromere loci along a single chromosome, chromosome 5. Comparison of neocentromere properties relative to native centromere functions revealed that all twenty neocentromeres mediated chromosome segregation, albeit to different degrees. Some neocentromeres also caused reduced levels of transcription from genes found within the neocentromere region. Furthermore, like native centromeres, neocentromeres clustered in 3D with active/functional centromeres, indicating that formation of a new centromere mediates the reorganization of 3D nuclear architecture. This demonstrates that centromere clustering depends on epigenetically defined function and not on the primary DNA sequence, and that neocentromere function is independent of its distance from the native centromere position. Together, the results show that a neocentromere can form at many loci along a chromosome and can support the assembly of a functional kinetochore that exhibits native centromere functions including chromosome segregation accuracy and centromere clustering within the nucleus.

Chromosomal contact permits transcription between coregulated genes

CSIR Research Space (South Africa)

Fanucchi, Stephanie

2013-10-01

Full Text Available . To ask whether chromosomal contacts are required for cotranscription in multigene complexes, we devised a strategy using TALENs to cleave and disrupt gene loops in a well-characterized multigene complex. Monitoring this disruption using RNA FISH...

Distinctive phenotype in 9 patients with deletion of chromosome 1q24-q25.

Science.gov (United States)

Burkardt, Deepika D'Cunha; Rosenfeld, Jill A; Helgeson, Maria L; Angle, Brad; Banks, Valerie; Smith, Wendy E; Gripp, Karen W; Moline, Jessica; Moran, Rocio T; Niyazov, Dmitriy M; Stevens, Cathy A; Zackai, Elaine; Lebel, Robert Roger; Ashley, Douglas G; Kramer, Nancy; Lachman, Ralph S; Graham, John M

2011-06-01

Reports of individuals with deletions of 1q24→q25 share common features of prenatal onset growth deficiency, microcephaly, small hands and feet, dysmorphic face and severe cognitive deficits. We report nine individuals with 1q24q25 deletions, who show distinctive features of a clinically recognizable 1q24q25 microdeletion syndrome: prenatal-onset microcephaly and proportionate growth deficiency, severe cognitive disability, small hands and feet with distinctive brachydactyly, single transverse palmar flexion creases, fifth finger clinodactyly and distinctive facial features: upper eyelid fullness, small ears, short nose with bulbous nasal tip, tented upper lip, and micrognathia. Radiographs demonstrate disharmonic osseous maturation with markedly delayed bone age. Occasional features include cleft lip and/or palate, cryptorchidism, brain and spinal cord defects, and seizures. Using oligonucleotide-based array comparative genomic hybridization, we defined the critical deletion region as 1.9 Mb at 1q24.3q25.1 (chr1: 170,135,865-172,099,327, hg18 coordinates), containing 13 genes and including CENPL, which encodes centromeric protein L, a protein essential for proper kinetochore function and mitotic progression. The growth deficiency in this syndrome is similar to what is seen in other types of primordial short stature with microcephaly, such as Majewski osteodysplastic primordial dwarfism, type II (MOPD2) and Seckel syndrome, which result from loss-of-function mutations in genes coding for centrosomal proteins. DNM3 is also in the deleted region and expressed in the brain, where it participates in the Shank-Homer complex and increases synaptic strength. Therefore, DNM3 is a candidate for the cognitive disability, and CENPL is a candidate for growth deficiency in this 1q24q25 microdeletion syndrome. Copyright © 2011 Wiley-Liss, Inc.

Inherited variants in the inner centromere protein (INCENP) gene of the chromosomal passenger complex contribute to the susceptibility of ER-negative breast cancer

NARCIS (Netherlands)

M. Kabisch (Maria); J.L. Bermejo (Justo Lorenzo); T. Dun̈nebier (Thomas); S. Ying (Shibo); K. Michailidou (Kyriaki); M.K. Bolla (Manjeet); Q. Wang (Qing); J. Dennis (Joe); M. Shah (Mitul); B. Perkins (Barbara); K. Czene (Kamila); H. Darabi (Hatef); M. Eriksson (Mikael); S.E. Bojesen (Stig); B.G. Nordestgaard (Børge); S.F. Nielsen (Sune); H. Flyger (Henrik); D. Lambrechts (Diether); P. Neven (Patrick); S.T.H. Peeters (Stephanie); C. Weltens (Caroline); F.J. Couch (Fergus); J.E. Olson (Janet); X. Wang (Xianshu); K. Purrington (Kristen); J. Chang-Claude (Jenny); A. Rudolph (Anja); P. Seibold (Petra); D. Flesch-Janys (Dieter); J. Peto (Julian); I. dos Santos Silva (Isabel); N. Johnson (Nichola); O. Fletcher (Olivia); H. Nevanlinna (Heli); T.A. Muranen (Taru); K. Aittomäki (Kristiina); C. Blomqvist (Carl); M.K. Schmidt (Marjanka); A. Broeks (Annegien); S. Cornelissen (Sten); F.B.L. Hogervorst (Frans); J. Li (Jingmei); J.S. Brand (Judith S.); M.K. Humphreys (Manjeet); P. Guénel (Pascal); T. Truong (Thérèse); F. Menegaux (Florence); M. Sanchez (Marie); B. Burwinkel (Barbara); F. Marme (Federick); R. Yang (Rongxi); P. Bugert (Peter); A. González-Neira (Anna); J. Benítez (Javier); M.P. Zamora (Pilar); J.I. Arias Pérez (José Ignacio); A. Cox (Angela); S.S. Cross (Simon); M.W.R. Reed (Malcolm); I.L. Andrulis (Irene); J.A. Knight (Julia); G. Glendon (Gord); S. Tchatchou (Sandrine); E.J. Sawyer (Elinor); I.P. Tomlinson (Ian); M. Kerin (Michael); N. Miller (Nicola); C.A. Haiman (Christopher); F.R. Schumacher (Fredrick); B.E. Henderson (Brian); L. Le Marchand (Loic); A. Lindblom (Annika); S. Margolin (Sara); M.J. Hooning (Maartje); A. Hollestelle (Antoinette); M. Kriege (Mieke); L.B. Koppert (Lisa); J. Hopper (John); M.C. Southey (Melissa); H. Tsimiklis (Helen); C. Apicella (Carmel); S. Slettedahl (Seth); A.E. Toland (Amanda); C. Vachon (Celine); D. Yannoukakos (Drakoulis); G.G. Giles (Graham); R.L. Milne (Roger); C.A. McLean (Catriona Ann); P.A. Fasching (Peter); M. Ruebner (Matthias); A.B. Ekici (Arif); M.W. Beckmann (Matthias); H. Brenner (Hermann); A.K. Dieffenbach (Aida Karina); V. Arndt (Volker); C. Stegmaier (Christa); A. Ashworth (Alan); N. Orr (Nick); M. Schoemaker (Minouk); A.J. Swerdlow (Anthony ); M. García-Closas (Montserrat); J.D. Figueroa (Jonine); S.J. Chanock (Stephen); J. Lissowska (Jolanta); M.S. Goldberg (Mark); F. Labrèche (France); M. Dumont (Martine); R. Winqvist (Robert); K. Pykäs (Katri); A. Jukkola-Vuorinen (Arja); M. Grip (Mervi); H. Brauch (Hiltrud); T. Brüning (Thomas); Y-D. Ko (Yon-Dschun); P. Radice (Paolo); P. Peterlongo (Paolo); G. Scuvera (Giulietta); S. Fortuzzi (S.); N.V. Bogdanova (Natalia); T. Dörk (Thilo); A. Mannermaa (Arto); V. Kataja (Vesa); V-M. Kosma (Veli-Matti); J.M. Hartikainen (J.); P. Devilee (Peter); R.A.M. Tollenaar (Robert A.M.); C.M. Seynaeve (Caroline); C.J. van Asperen (Christi); A. Jakubowska (Anna); J. Lubinski (Jan); K. Jaworska-Bieniek (Katarzyna); K. Durda (Katarzyna); W. Zheng (Wei); M. Shrubsole (Martha); Q. Cai (Qiuyin); D. Torres (Diana); H. Anton-Culver (Hoda); V. Kristensen (Vessela); F. Bacot (Francois); D.C. Tessier (Daniel C.); D. Vincent (Daniel); C. Luccarini (Craig); C. Baynes (Caroline); S. Ahmed (Shahana); M. Maranian (Melanie); J. Simard (Jacques); G. Chenevix-Trench (Georgia); P. Hall (Per); P.D.P. Pharoah (Paul); A.M. Dunning (Alison); D.F. Easton (Douglas); U. Hamann (Ute)

2014-01-01

textabstractThe chromosomal passenger complex (CPC) plays a pivotal role in the regulation of cell division. Therefore, inherited CPC variability could influence tumor development. The present candidate gene approach investigates the relationship between single nucleotide polymorphisms (SNPs) in

Chromosome Mis-segregation Generates Cell-Cycle-Arrested Cells with Complex Karyotypes that Are Eliminated by the Immune System.

Science.gov (United States)

Santaguida, Stefano; Richardson, Amelia; Iyer, Divya Ramalingam; M'Saad, Ons; Zasadil, Lauren; Knouse, Kristin A; Wong, Yao Liang; Rhind, Nicholas; Desai, Arshad; Amon, Angelika

2017-06-19

Aneuploidy, a state of karyotype imbalance, is a hallmark of cancer. Changes in chromosome copy number have been proposed to drive disease by modulating the dosage of cancer driver genes and by promoting cancer genome evolution. Given the potential of cells with abnormal karyotypes to become cancerous, do pathways that limit the prevalence of such cells exist? By investigating the immediate consequences of aneuploidy on cell physiology, we identified mechanisms that eliminate aneuploid cells. We find that chromosome mis-segregation leads to further genomic instability that ultimately causes cell-cycle arrest. We further show that cells with complex karyotypes exhibit features of senescence and produce pro-inflammatory signals that promote their clearance by the immune system. We propose that cells with abnormal karyotypes generate a signal for their own elimination that may serve as a means for cancer cell immunosurveillance. Copyright © 2017 Elsevier Inc. All rights reserved.

New chromosome characteristics of the monozoic tapeworm Caryophyllaeus laticeps (Cestoda, Caryophyllidea

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Bombarová M.

2015-12-01

Full Text Available The karyotype of a caryophyllidean tapeworm Caryophyllaeus laticeps (Pallas, 1781 from the freshwater bream Abramis brama (L. caught in the Slovak part of the River Tisa, was described and originally inspected for amount of heterochromatin and its chromosome localization. The chromosome set comprised nine metacentric and one submetacentric (No. 3 pairs (2n = 20. The chromosomes were up to 12.0 ± 2.5 μm long and the mean total length of haploid genome (TLC reached 80.6 μm that represents one of the highest yet recorded values among tapeworms. C-banding and staining with fl uorescent dyes DAPI and YOYO1 revealed a distinct banding pattern explicitly on chromosomes with centromeric bright heterochromatin bands present on all 10 chromosome pairs; no pair showed any interstitial heterochromatin. A complete course of spermatocyte meiosis and dynamics of nucleolus formation and degradation during meiotic division was described.

TRF2 Protein Interacts with Core Histones to Stabilize Chromosome Ends.

Science.gov (United States)

Konishi, Akimitsu; Izumi, Takashi; Shimizu, Shigeomi

2016-09-23

Mammalian chromosome ends are protected by a specialized nucleoprotein complex called telomeres. Both shelterin, a telomere-specific multi-protein complex, and higher order telomeric chromatin structures combine to stabilize the chromosome ends. Here, we showed that TRF2, a component of shelterin, binds to core histones to protect chromosome ends from inappropriate DNA damage response and loss of telomeric DNA. The N-terminal Gly/Arg-rich domain (GAR domain) of TRF2 directly binds to the globular domain of core histones. The conserved arginine residues in the GAR domain of TRF2 are required for this interaction. A TRF2 mutant with these arginine residues substituted by alanine lost the ability to protect telomeres and induced rapid telomere shortening caused by the cleavage of a loop structure of the telomeric chromatin. These findings showed a previously unnoticed interaction between the shelterin complex and nucleosomal histones to stabilize the chromosome ends. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

TRF2 Protein Interacts with Core Histones to Stabilize Chromosome Ends*

Science.gov (United States)

Izumi, Takashi; Shimizu, Shigeomi

2016-01-01

Mammalian chromosome ends are protected by a specialized nucleoprotein complex called telomeres. Both shelterin, a telomere-specific multi-protein complex, and higher order telomeric chromatin structures combine to stabilize the chromosome ends. Here, we showed that TRF2, a component of shelterin, binds to core histones to protect chromosome ends from inappropriate DNA damage response and loss of telomeric DNA. The N-terminal Gly/Arg-rich domain (GAR domain) of TRF2 directly binds to the globular domain of core histones. The conserved arginine residues in the GAR domain of TRF2 are required for this interaction. A TRF2 mutant with these arginine residues substituted by alanine lost the ability to protect telomeres and induced rapid telomere shortening caused by the cleavage of a loop structure of the telomeric chromatin. These findings showed a previously unnoticed interaction between the shelterin complex and nucleosomal histones to stabilize the chromosome ends. PMID:27514743

Specific gene expression profiles and chromosomal abnormalities are associated with infant disseminated neuroblastoma

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Kushner Brian

2009-02-01

Full Text Available Abstract Background Neuroblastoma (NB tumours have the highest incidence of spontaneous remission, especially among the stage 4s NB subgroup affecting infants. Clinical distinction of stage 4s from lethal stage 4 can be difficult, but critical for therapeutic decisions. The aim of this study was to investigate chromosomal alterations and differential gene expression amongst infant disseminated NB subgroups. Methods Thirty-five NB tumours from patients diagnosed at Results All stage 4s patients underwent spontaneous remission, only 48% stage 4 patients survived despite combined modality therapy. Stage 4 tumours were 90% near-diploid/tetraploid, 44% MYCN amplified, 77% had 1p LOH (50% 1p36, 23% 11q and/or 14q LOH (27% and 47% had 17q gain. Stage 4s were 90% near-triploid, none MYCN amplified and LOH was restricted to 11q. Initial comparison analyses between stage 4s and 4 P P = 0.0054, 91% with higher expression in stage 4. Less definite expression profiles were observed between stage 4s and 4 P P = 0.005 was maintained. Distinct gene expression profiles but no significant association with specific chromosomal region localization was observed between stage 4s and stage 4 Conclusion Specific chromosomal aberrations are associated with distinct gene expression profiles which characterize spontaneously regressing or aggressive infant NB, providing the biological basis for the distinct clinical behaviour.

Genomic regulatory landscapes and chromosomal rearrangements

DEFF Research Database (Denmark)

Ladegaard, Elisabete L Engenheiro

2008-01-01

The main objectives of the PhD study are to identify and characterise chromosomal rearrangements within evolutionarily conserved regulatory landscapes around genes involved in the regulation of transcription and/or development (trans-dev genes). A frequent feature of trans-dev genes is that they ......The main objectives of the PhD study are to identify and characterise chromosomal rearrangements within evolutionarily conserved regulatory landscapes around genes involved in the regulation of transcription and/or development (trans-dev genes). A frequent feature of trans-dev genes...... the complex spatio-temporal expression of the associated trans-dev gene. Rare chromosomal breakpoints that disrupt the integrity of these regulatory landscapes may be used as a tool, not only to make genotype-phenotype associations, but also to link the associated phenotype with the position and tissue...... specificity of the individual CNEs. In this PhD study I have studied several chromosomal rearrangements with breakpoints in the vicinity of trans-dev genes. This included chromosomal rearrangements compatible with known phenotype-genotype associations (Rieger syndrome-PITX2, Mowat-Wilson syndrome-ZEB2...

Congressing kinetochores progressively load Ska complexes to prevent force-dependent detachment.

Science.gov (United States)

Auckland, Philip; Clarke, Nicholas I; Royle, Stephen J; McAinsh, Andrew D

2017-06-05

Kinetochores mediate chromosome congression by either sliding along the lattice of spindle microtubules or forming end-on attachments to their depolymerizing plus-ends. By following the fates of individual kinetochores as they congress in live cells, we reveal that the Ska complex is required for a distinct substep of the depolymerization-coupled pulling mechanism. Ska depletion increases the frequency of naturally occurring, force-dependent P kinetochore detachment events, while being dispensable for the initial biorientation and movement of chromosomes. In unperturbed cells, these release events are followed by reattachment and successful congression, whereas in Ska-depleted cells, detached kinetochores remain in a futile reattachment/detachment cycle that prevents congression. We further find that Ska is progressively loaded onto bioriented kinetochore pairs as they congress. We thus propose a model in which kinetochores mature through Ska complex recruitment and that this is required for improved load-bearing capacity and silencing of the spindle assembly checkpoint. © 2017 Auckland et al.

Distinct growth of the nasomaxillary complex in Au. sediba.

Science.gov (United States)

Lacruz, Rodrigo S; Bromage, Timothy G; O'Higgins, Paul; Toro-Ibacache, Viviana; Warshaw, Johanna; Berger, Lee R

2015-10-15

Studies of facial ontogeny in immature hominins have contributed significantly to understanding the evolution of human growth and development. The recently discovered hominin species Autralopithecus sediba is represented by a well-preserved and nearly complete facial skeleton of a juvenile (MH1) which shows a derived facial anatomy. We examined MH1 using high radiation synchrotron to interpret features of the oronasal complex pertinent to facial growth. We also analyzed bone surface microanatomy to identify and map fields of bone deposition and bone resorption, which affect the development of the facial skeleton. The oronasal anatomy (premaxilla-palate-vomer architecture) is similar to other Australopithecus species. However surface growth remodeling of the midface (nasomaxillary complex) differs markedly from Australopithecus, Paranthropus, early Homo and from KNM-WT 15000 (H. erectus/ergaster) showing a distinct distribution of vertically disposed alternating depository and resorptive fields in relation to anterior dental roots and the subnasal region. The ontogeny of the MH1 midface superficially resembles some H. sapiens in the distribution of remodeling fields. The facial growth of MH1 appears unique among early hominins representing an evolutionary modification in facial ontogeny at 1.9 my, or to changes in masticatory system loading associated with diet.

[Tripartite motif-containing protein 34 (TRIM34) colocalized with micronuclei chromosome and hampers its movement to equatorial plate during the metaphase stage of mitosis].

Science.gov (United States)

Sun, Dakang; An, Xinye; Ji, Bing; Cheng, Yanli; Gao, Honglian; Tian, Mingming

2016-06-01

Objective To examine whether tripartite motif-containing protein 34 (TRIM34) is colocalized with micronuclei and investigate the influence on the movement of micronuclei chromosome in mitosis. Methods The eukaryotic expression vector TRIM34-pEGFP-N3 was constructed, identified and then transfected into HEK293T cells. With 4', 6-diamidino-2-phenylindole 2HCI (DAPI) staining, the colocalization between TRIM34 and micronuclei was observed under a fluorescence microscope. Moreover, MitoTracker(R)Deep Red was used to identify the colocalization between the complex of TRIM34-micronulei and mitochondria under a confocal microscope. Finally, the effect of TRIM34 on the movement of micronuclei chromosome in mitosis was examined. Results DNA sequencing confirmed that the vector TRIM34-pEGFP-N3 was constructed successfully. A fluorescence microscope revealed that TRIM34 could be colocalized with micronuclei in HEK293T cells transfected with TRIM34-pEGFP-N3. In the same manner, a confocal microscope distinctly showed that TRIM34 was colocalized with micronuclei similarly in appearance. However, there was no distinguished colocalization relationship between the complex of TRIM34-micronulei and mitochondria. Interestingly, the micronuclei chromosome conjugated with TRIM34 was hardly transferred to equatorial plate during the metaphase stage of mitosis. Conclusion TRIM34 is colocalized with micronuclei chromosome and hampers its movement to equatorial plate in mitosis.

Constitutional abnormalities of chromosome 21 predispose to iAMP21-acute lymphoblastic leukaemia.

Science.gov (United States)

Harrison, Christine J; Schwab, Claire

2016-03-01

In addition to Down syndrome, individuals with other constitutional abnormalities of chromosome 21 have an increased risk of developing childhood acute lymphoblastic leukaemia (ALL). Specifically, carriers of the Robertsonian translocation between chromosomes 15 and 21, rob(15;21) (q10; q10)c, have ∼2,700 increased risk of developing ALL with iAMP21 (intrachromosomal amplification of chromosome 21). In these patients, chromosome 15 as well as chromosome 21 is involved in the formation of iAMP21, referred to here as der(21)(15;21). Individuals with constitutional ring chromosomes involving chromosome 21, r(21)c, are also predisposed to iAMP21-ALL, involving the same series of mutational processes as seen in sporadic- and der(21)(15;21)-iAMP21 ALL. Evidence is accumulating that the dicentric nature of the Robertsonian and ring chromosome is the initiating factor in the formation of the complex iAMP21 structure. Unravelling these intriguing predispositions to iAMP21-ALL may provide insight into how other complex rearrangements arise in cancer. Copyright © 2016. Published by Elsevier Masson SAS.

Localization of latency-associated nuclear antigen (LANA) on mitotic chromosomes

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Rahayu, Retno; Ohsaki, Eriko [Division of Virology, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871 (Japan); Omori, Hiroko [Central Instrumentation Laboratory Research Institute for Microbial Diseases (BIKEN), Osaka University, Osaka 565-0871 (Japan); Ueda, Keiji, E-mail: kueda@virus.med.osaka-u.ac.jp [Division of Virology, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2016-09-15

In latent infection of Kaposi's sarcoma-associated herpesvirus (KSHV), viral gene expression is extremely limited and copy numbers of viral genomes remain constant. Latency-associated nuclear antigen (LANA) is known to have a role in maintaining viral genome copy numbers in growing cells. Several studies have shown that LANA is localized in particular regions on mitotic chromosomes, such as centromeres/pericentromeres. We independently examined the distinct localization of LANA on mitotic chromosomes during mitosis, using super-resolution laser confocal microscopy and correlative fluorescence microscopy–electron microscopy (FM-EM) analyses. We found that the majority of LANA were not localized at particular regions such as telomeres/peritelomeres, centromeres/pericentromeres, and cohesion sites, but at the bodies of condensed chromosomes. Thus, LANA may undergo various interactions with the host factors on the condensed chromosomes in order to tether the viral genome to mitotic chromosomes and realize faithful viral genome segregation during cell division. - Highlights: • This is the first report showing LANA dots on mitotic chromosomes by fluorescent microscopy followed by electron microscopy. • LANA dots localized randomly on condensed chromosomes other than centromere/pericentromere and telomere/peritelomre. • Cellular mitotic checkpoint should not be always involved in the segregation of KSHV genomes in the latency.

Localization of latency-associated nuclear antigen (LANA) on mitotic chromosomes

International Nuclear Information System (INIS)

Rahayu, Retno; Ohsaki, Eriko; Omori, Hiroko; Ueda, Keiji

2016-01-01

In latent infection of Kaposi's sarcoma-associated herpesvirus (KSHV), viral gene expression is extremely limited and copy numbers of viral genomes remain constant. Latency-associated nuclear antigen (LANA) is known to have a role in maintaining viral genome copy numbers in growing cells. Several studies have shown that LANA is localized in particular regions on mitotic chromosomes, such as centromeres/pericentromeres. We independently examined the distinct localization of LANA on mitotic chromosomes during mitosis, using super-resolution laser confocal microscopy and correlative fluorescence microscopy–electron microscopy (FM-EM) analyses. We found that the majority of LANA were not localized at particular regions such as telomeres/peritelomeres, centromeres/pericentromeres, and cohesion sites, but at the bodies of condensed chromosomes. Thus, LANA may undergo various interactions with the host factors on the condensed chromosomes in order to tether the viral genome to mitotic chromosomes and realize faithful viral genome segregation during cell division. - Highlights: • This is the first report showing LANA dots on mitotic chromosomes by fluorescent microscopy followed by electron microscopy. • LANA dots localized randomly on condensed chromosomes other than centromere/pericentromere and telomere/peritelomre. • Cellular mitotic checkpoint should not be always involved in the segregation of KSHV genomes in the latency.

Chromosome aberrations in pesticide-exposed greenhouse workers

DEFF Research Database (Denmark)

Lander, B F; Knudsen, Lisbeth E.; Gamborg, M O

2000-01-01

OBJECTIVES: The aim of this study was to investigate the possibility of subtoxic exposure to pesticides causing chromosome aberrations in greenhouse workers. METHODS: In a cross-sectional and prospective study design chromosome aberration frequencies in cultured lymphocytes were examined for 116...... greenhouse workers exposed to a complex mixture of almost 50 insecticides, fungicides, and growth regulators and also for 29 nonsmoking, nonpesticide-exposed referents. RESULTS: The preseason frequencies of chromosome aberrations were slightly but not statistically significantly elevated for the greenhouse...... workers when they were compared with the referents. After a summer season of pesticide spraying in the greenhouses, the total frequencies of cells with chromosome aberrations were significantly higher than in the preseason samples (P=0.02) and also higher than for the referents (P=0.05). This finding...

Chromosome homogeneity in populations of Triatoma brasiliensis Neiva 1911 (Hemiptera - Reduviidae - Triatominae

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Panzera Francisco

2000-01-01

Full Text Available Triatoma brasiliensis is the most important vector of Chagas disease in the semiarid zone of the Northeast of Brazil. Several authors have reported the occurrence of four chromatic patterns with morphological, ecological, and genetic differences. In order to determine the existence of cytogenetic differentiation between these chromatic forms, we analyzed their karyotypes and the chromosome behavior during the male meiotic process. Triatoma brasiliensis shows distinct and specific chromosome characteristics, which differ from those observed in all other triatomine species. However, no cytogenetic differences were observed between the four chromatic forms of T. brasiliensis. The lack of chromosome differentiation among them could indicate that the populations of this species are in a process of differentiation that does not involve their chromosomal organization.

Chromosomal Abnormalities Associated With Omphalocele

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Chih-Ping Chen

2007-03-01

Full Text Available Fetuses with omphalocele have an increased risk for chromosomal abnormalities. The risk varies with maternal age, gestational age at diagnosis, association with umbilical cord cysts, complexity of associated anomalies, and the contents of omphalocele. There is considerable evidence that genetics contributes to the etiology of omphalocele. This article provides an overview of chromosomal abnormalities associated with omphalocele and a comprehensive review of associated full aneuploidy such as trisomy 18, trisomy 13, triploidy, trisomy 21, 45,X, 47,XXY, and 47,XXX, partial aneuploidy such as dup(3q, dup(11p, inv(11, dup(1q, del(1q, dup(4q, dup(5p, dup(6q, del(9p, dup(15q, dup(17q, Pallister-Killian syndrome with mosaic tetrasomy 12p and Miller-Dieker lissencephaly syndrome with deletion of 17p13.3, and uniparental disomy (UPD such as UPD 11 and UPD 14. Omphalocele is a prominent marker for chromosomal abnormalities. Perinatal identification of omphalocele should alert chromosomal abnormalities and familial unbalanced translocations, and prompt thorough cytogenetic investigations and genetic counseling.

Identification of two distinct chromosome 12-derived amplification units in neuroblastoma cell line NGP

NARCIS (Netherlands)

van Roy, N.; Forus, A.; Myklebost, O.; Cheng, N. C.; Versteeg, R.; Speleman, F.

1995-01-01

The neuroblastoma cell line NGP contains two homogeneously staining regions (hsr). One of these hsrs contains MYCN sequences. Reverse painting experiments demonstrated that the second HSR consisted of two chromosome 12-derived amplification units, located at 12q14-15 and 12q24. Southern blot and

Complex evolutionary trajectories of sex chromosomes across bird taxa

DEFF Research Database (Denmark)

Zhou, Qi; Zhang, Jilin; Bachtrog, Doris

2014-01-01

Sex-specific chromosomes, like the W of most female birds and the Y of male mammals, usually have lost most genes owing to a lack of recombination.We analyze newly available genomes of 17 bird species representing the avian phylogenetic range, and find that more than half of them do not have...

Mapping Breakpoints of Complex Chromosome Rearrangements Involving a Partial Trisomy 15q23.1-q26.2 Revealed by Next Generation Sequencing and Conventional Techniques.

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Qiong Pan

Full Text Available Complex chromosome rearrangements (CCRs, which are rather rare in the whole population, may be associated with aberrant phenotypes. Next-generation sequencing (NGS and conventional techniques, could be used to reveal specific CCRs for better genetic counseling. We report the CCRs of a girl and her mother, which were identified using a combination of NGS and conventional techniques including G-banding, fluorescence in situ hybridization (FISH and PCR. The girl demonstrated CCRs involving chromosomes 3 and 8, while the CCRs of her mother involved chromosomes 3, 5, 8, 11 and 15. HumanCytoSNP-12 Chip analysis identified a 35.4 Mb duplication on chromosome 15q21.3-q26.2 in the proband and a 1.6 Mb microdeletion at chromosome 15q21.3 in her mother. The proband inherited the rearranged chromosomes 3 and 8 from her mother, and the duplicated region on chromosome 15 of the proband was inherited from the mother. Approximately one hundred genes were identified in the 15q21.3-q26.2 duplicated region of the proband. In particular, TPM1, SMAD6, SMAD3, and HCN4 may be associated with her heart defects, and HEXA, KIF7, and IDH2 are responsible for her developmental and mental retardation. In addition, we suggest that a microdeletion on the 15q21.3 region of the mother, which involved TCF2, TCF12, ADMA10 and AQP9, might be associated with mental retardation. We delineate the precise structures of the derivative chromosomes, chromosome duplication origin and possible molecular mechanisms for aberrant phenotypes by combining NGS data with conventional techniques.

Aberrations of chromosome 8 in myelodysplastic syndromes: Clinical and biological significance

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Marisavljević Dragomir

2006-01-01

Full Text Available Introduction: Rearrangements of any single chromosome in human karyotype have been reported in patients with pMDS. Objective: To examine the role of aberrations of chromosome 8 in pathogenesis, clinical presentation and progression of myelodysplastic syndromes. Method: Cytogenetic analysis of bone marrow cells was carried out by direct method and by means of 24- and/or 48-hour unstimulated cell culture. Chromosomes were obtained by modified method of HG-bands. Results: On presentation, 109 out of 271 successfully karyotyped patients (40,2% had abnormal karyotypes. Among them, 22 patients (10.9% had aberrations of chromosome 8. Ten patients had trisomy 8 as "simple" aberration whilst additional three cases had trisomy 8 included in "complex" karyotypes (≥3 chromosomes. Cases with constitutional trisomy 8 mosaicism (CT8M were excluded using the chromosome analyses of PHA-stimulated blood cultures. On the contrary, monosomy (seven patients or deletion of chromosome 8 (two patients were exclusively found in "complex" karyotypes. During prolonged cytogenetic follow-up, trisomy 8 was not recorded in evolving karyotypes. In contrast, trisomy 8 disappeared in two cases during subsequent cytogenetic studies, i.e. 23 and 72 months from diagnosis, accompanied in one patient with complete hematological remission. No difference regarding age, sex, cytopenia, blood and marrow blast count or response to treatment was found between patients with trisomy 8 as the sole aberration compared to those with normal cytogenetics. Median survival of patients with trisomy 8 as the sole aberration was 27 months, as compared to 32 months in patients with normal cytogenetics (p=0.468, whilst median survival of patients with aberrations of chromosome 8 included in "complex" karyotypes was only 4 months. Conclusion: Aberrations of chromosome 8 are common in patients with pMDS. The presence of a clone with trisomy 8 is not always the sign of disease progression or poor

SCAI promotes DNA double-strand break repair in distinct chromosomal contexts

DEFF Research Database (Denmark)

Hansen, Rebecca Kring; Mund, Andreas; Poulsen, Sara Lund

2016-01-01

cell invasion) as a 53BP1-interacting chromatin-associated protein that promotes the functionality of several DSB repair pathways in mammalian cells. SCAI undergoes prominent enrichment at DSB sites through dual mechanisms involving 53BP1-dependent recruitment to DSB-surrounding chromatin and 53BP1...... in repressive chromatin environments. Moreover, we establish an important role of SCAI in meiotic recombination, as SCAI deficiency in mice leads to germ cell loss and subfertility associated with impaired retention of the DMC1 recombinase on meiotic chromosomes. Collectively, our findings uncover SCAI...... as a physiologically important component of both NHEJ- and HR-mediated pathways that potentiates DSB repair efficiency in specific chromatin contexts....

X chromosome control of meiotic chromosome synapsis in mouse inter-subspecific hybrids.

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Tanmoy Bhattacharyya

2014-02-01

Full Text Available Hybrid sterility (HS belongs to reproductive isolation barriers that safeguard the integrity of species in statu nascendi. Although hybrid sterility occurs almost universally among animal and plant species, most of our current knowledge comes from the classical genetic studies on Drosophila interspecific crosses or introgressions. With the house mouse subspecies Mus m. musculus and Mus m. domesticus as a model, new research tools have become available for studies of the molecular mechanisms and genetic networks underlying HS. Here we used QTL analysis and intersubspecific chromosome substitution strains to identify a 4.7 Mb critical region on Chromosome X (Chr X harboring the Hstx2 HS locus, which causes asymmetrical spermatogenic arrest in reciprocal intersubspecific F1 hybrids. Subsequently, we mapped autosomal loci on Chrs 3, 9 and 13 that can abolish this asymmetry. Combination of immunofluorescent visualization of the proteins of synaptonemal complexes with whole-chromosome DNA FISH on pachytene spreads revealed that heterosubspecific, unlike consubspecific, homologous chromosomes are predisposed to asynapsis in F1 hybrid male and female meiosis. The asynapsis is under the trans- control of Hstx2 and Hst1/Prdm9 hybrid sterility genes in pachynemas of male but not female hybrids. The finding concurred with the fertility of intersubpecific F1 hybrid females homozygous for the Hstx2(Mmm allele and resolved the apparent conflict with the dominance theory of Haldane's rule. We propose that meiotic asynapsis in intersubspecific hybrids is a consequence of cis-acting mismatch between homologous chromosomes modulated by the trans-acting Hstx2 and Prdm9 hybrid male sterility genes.

X chromosome control of meiotic chromosome synapsis in mouse inter-subspecific hybrids.

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Bhattacharyya, Tanmoy; Reifova, Radka; Gregorova, Sona; Simecek, Petr; Gergelits, Vaclav; Mistrik, Martin; Martincova, Iva; Pialek, Jaroslav; Forejt, Jiri

2014-02-01

Hybrid sterility (HS) belongs to reproductive isolation barriers that safeguard the integrity of species in statu nascendi. Although hybrid sterility occurs almost universally among animal and plant species, most of our current knowledge comes from the classical genetic studies on Drosophila interspecific crosses or introgressions. With the house mouse subspecies Mus m. musculus and Mus m. domesticus as a model, new research tools have become available for studies of the molecular mechanisms and genetic networks underlying HS. Here we used QTL analysis and intersubspecific chromosome substitution strains to identify a 4.7 Mb critical region on Chromosome X (Chr X) harboring the Hstx2 HS locus, which causes asymmetrical spermatogenic arrest in reciprocal intersubspecific F1 hybrids. Subsequently, we mapped autosomal loci on Chrs 3, 9 and 13 that can abolish this asymmetry. Combination of immunofluorescent visualization of the proteins of synaptonemal complexes with whole-chromosome DNA FISH on pachytene spreads revealed that heterosubspecific, unlike consubspecific, homologous chromosomes are predisposed to asynapsis in F1 hybrid male and female meiosis. The asynapsis is under the trans- control of Hstx2 and Hst1/Prdm9 hybrid sterility genes in pachynemas of male but not female hybrids. The finding concurred with the fertility of intersubpecific F1 hybrid females homozygous for the Hstx2(Mmm) allele and resolved the apparent conflict with the dominance theory of Haldane's rule. We propose that meiotic asynapsis in intersubspecific hybrids is a consequence of cis-acting mismatch between homologous chromosomes modulated by the trans-acting Hstx2 and Prdm9 hybrid male sterility genes.

X Chromosome Control of Meiotic Chromosome Synapsis in Mouse Inter-Subspecific Hybrids

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Bhattacharyya, Tanmoy; Reifova, Radka; Gregorova, Sona; Simecek, Petr; Gergelits, Vaclav; Mistrik, Martin; Martincova, Iva; Pialek, Jaroslav; Forejt, Jiri

2014-01-01

Hybrid sterility (HS) belongs to reproductive isolation barriers that safeguard the integrity of species in statu nascendi. Although hybrid sterility occurs almost universally among animal and plant species, most of our current knowledge comes from the classical genetic studies on Drosophila interspecific crosses or introgressions. With the house mouse subspecies Mus m. musculus and Mus m. domesticus as a model, new research tools have become available for studies of the molecular mechanisms and genetic networks underlying HS. Here we used QTL analysis and intersubspecific chromosome substitution strains to identify a 4.7 Mb critical region on Chromosome X (Chr X) harboring the Hstx2 HS locus, which causes asymmetrical spermatogenic arrest in reciprocal intersubspecific F1 hybrids. Subsequently, we mapped autosomal loci on Chrs 3, 9 and 13 that can abolish this asymmetry. Combination of immunofluorescent visualization of the proteins of synaptonemal complexes with whole-chromosome DNA FISH on pachytene spreads revealed that heterosubspecific, unlike consubspecific, homologous chromosomes are predisposed to asynapsis in F1 hybrid male and female meiosis. The asynapsis is under the trans- control of Hstx2 and Hst1/Prdm9 hybrid sterility genes in pachynemas of male but not female hybrids. The finding concurred with the fertility of intersubpecific F1 hybrid females homozygous for the Hstx2Mmm allele and resolved the apparent conflict with the dominance theory of Haldane's rule. We propose that meiotic asynapsis in intersubspecific hybrids is a consequence of cis-acting mismatch between homologous chromosomes modulated by the trans-acting Hstx2 and Prdm9 hybrid male sterility genes. PMID:24516397

Chromosome

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... St Louis, MO: Elsevier; 2017:chap 69. Taber's Medical Dictionary Online. Chromosome. www.tabers.com/tabersonline/view/Tabers-Dictionary/753321/all/chromosome?q=Chromosome&ti=0 . Accessed June 11, 2017.

Isodicentric chromosome 21: a novel aberration in acute myeloid leukemia.

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Sankar, M; Tanaka, K; Arif, M; Shintani, T; Kumaravel, T S; Kyo, T; Dohy, H; Kamada, N

1998-11-01

We present here a 78-year-old female patient with acute myeloid leukemia (AML), French-American-British classification M2, exhibiting isodicentric chromosome 21, idic(21)(q22), at the time of diagnosis. The patient had three idic(21)(q22), besides the del(5)(q13q32), add(21)(q22), dic(21;22) (q22;q13), and +22. Fluorescence in situ hybridization studies with whole-chromosome painting and centromere-specific probes for chromosome 21 verified the diagnosis of idic(21)(q22). There were no distinct clinicohematological characteristics of AML with isodicentric 21. The patient was treated with remission-induction therapy followed by consolidation therapy. Two years later, the patient showed the disappearance of isodicentric 21 but retained del(5)(q13q32) and gained other chromosomal abnormalities, +add(17)(p11) and -16. To our knowledge, this is the first report of AML with acquired idic(21)(q22).

Molecular mechanism in the formation of a human ring chromosome 21

International Nuclear Information System (INIS)

Wong, C.; Kazazian, H.H. Jr.; Stetten, G.; Earnshaw, W.C.; Antonarakis, S.E.; Van Keuren, M.L.

1989-01-01

The authors have characterized the structural rearrangements of a chromosome 21 that led to the de novo formation of a human ring chromosome 21 [r(21)]. Molecular cloning and chromosomal localization of the DNA regions flanking the ring junction provide evidence for a long arm to long arm fusion in formation of the r(21). In addition, the centromere and proximal long arm region of a maternal chromosome 21 are duplicated in the r(21). Therefore, the mechanism in formation of the r(21) was complex involving two sequential chromosomal rearrangements. (i) Duplication of the centromere and long arm of one maternal chromosome 21 occurred forming a rearranged intermediate. (ii) Chromosomal breaks in both the proximal and telomeric long arm regions on opposite arms of this rearranged chromosome occurred with subsequent reunion producing the r(21)

Rac1 GTPase activates the WAVE regulatory complex through two distinct binding sites

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Brautigam, Chad A; Xing, Wenmin; Yang, Sheng; Henry, Lisa; Doolittle, Lynda K; Walz, Thomas

2017-01-01

The Rho GTPase Rac1 activates the WAVE regulatory complex (WRC) to drive Arp2/3 complex-mediated actin polymerization, which underpins diverse cellular processes. Here we report the structure of a WRC-Rac1 complex determined by cryo-electron microscopy. Surprisingly, Rac1 is not located at the binding site on the Sra1 subunit of the WRC previously identified by mutagenesis and biochemical data. Rather, it binds to a distinct, conserved site on the opposite end of Sra1. Biophysical and biochemical data on WRC mutants confirm that Rac1 binds to both sites, with the newly identified site having higher affinity and both sites required for WRC activation. Our data reveal that the WRC is activated by simultaneous engagement of two Rac1 molecules, suggesting a mechanism by which cells may sense the density of active Rac1 at membranes to precisely control actin assembly. PMID:28949297

The Monopolin Complex Crosslinks Kinetochore Components to Regulate Chromosome-Microtubule Attachments

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Corbett, Kevin D.; Yip, Calvin K.; Ee, Ly-Sha; Walz, Thomas; Amon, Angelika; Harrison, Stephen C. (Harvard-Med); (MIT)

2010-09-27

The monopolin complex regulates different types of kinetochore-microtubule attachments in fungi, ensuring sister chromatid co-orientation in Saccharomyces cerevisiae meiosis I and inhibiting merotelic attachment in Schizosaccharomyces pombe mitosis. In addition, the monopolin complex maintains the integrity and silencing of ribosomal DNA (rDNA) repeats in the nucleolus. We show here that the S. cerevisiae Csm1/Lrs4 monopolin subcomplex has a distinctive V-shaped structure, with two pairs of protein-protein interaction domains positioned {approx}10 nm apart. Csm1 presents a conserved hydrophobic surface patch that binds two kinetochore proteins: Dsn1, a subunit of the outer-kinetochore MIND/Mis12 complex, and Mif2/CENP-C. Csm1 point-mutations that disrupt kinetochore-subunit binding also disrupt sister chromatid co-orientation in S. cerevisiae meiosis I. We further show that the same Csm1 point-mutations affect rDNA silencing, probably by disrupting binding to the rDNA-associated protein Tof2. We propose that Csm1/Lrs4 functions as a molecular clamp, crosslinking kinetochore components to enforce sister chromatid co-orientation in S. cerevisiae meiosis I and to suppress merotelic attachment in S. pombe mitosis, and crosslinking rDNA repeats to aid rDNA silencing.

Can molecular cell biology explain chromosome motions?

Directory of Open Access Journals (Sweden)

Gagliardi L

2011-05-01

Full Text Available Abstract Background Mitotic chromosome motions have recently been correlated with electrostatic forces, but a lingering "molecular cell biology" paradigm persists, proposing binding and release proteins or molecular geometries for force generation. Results Pole-facing kinetochore plates manifest positive charges and interact with negatively charged microtubule ends providing the motive force for poleward chromosome motions by classical electrostatics. This conceptual scheme explains dynamic tracking/coupling of kinetochores to microtubules and the simultaneous depolymerization of kinetochore microtubules as poleward force is generated. Conclusion We question here why cells would prefer complex molecular mechanisms to move chromosomes when direct electrostatic interactions between known bound charge distributions can accomplish the same task much more simply.

Major Histocompatibility Complex Genes Map to Two Chromosomes in an Evolutionarily Ancient Reptile, the Tuatara Sphenodon punctatus.

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Miller, Hilary C; O'Meally, Denis; Ezaz, Tariq; Amemiya, Chris; Marshall-Graves, Jennifer A; Edwards, Scott

2015-05-07

Major histocompatibility complex (MHC) genes are a central component of the vertebrate immune system and usually exist in a single genomic region. However, considerable differences in MHC organization and size exist between different vertebrate lineages. Reptiles occupy a key evolutionary position for understanding how variation in MHC structure evolved in vertebrates, but information on the structure of the MHC region in reptiles is limited. In this study, we investigate the organization and cytogenetic location of MHC genes in the tuatara (Sphenodon punctatus), the sole extant representative of the early-diverging reptilian order Rhynchocephalia. Sequencing and mapping of 12 clones containing class I and II MHC genes from a bacterial artificial chromosome library indicated that the core MHC region is located on chromosome 13q. However, duplication and translocation of MHC genes outside of the core region was evident, because additional class I MHC genes were located on chromosome 4p. We found a total of seven class I sequences and 11 class II β sequences, with evidence for duplication and pseudogenization of genes within the tuatara lineage. The tuatara MHC is characterized by high repeat content and low gene density compared with other species and we found no antigen processing or MHC framework genes on the MHC gene-containing clones. Our findings indicate substantial differences in MHC organization in tuatara compared with mammalian and avian MHCs and highlight the dynamic nature of the MHC. Further sequencing and annotation of tuatara and other reptile MHCs will determine if the tuatara MHC is representative of nonavian reptiles in general. Copyright © 2015 Miller et al.

Presence of three distinct genotypes within the Paragonimus westermani complex in northeastern India.

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Rekha Devi, K; Narain, Kanwar; Mahanta, Jagadish; Nirmolia, Tulika; Blair, David; Saikia, Sidhartha P; Agatsuma, Takeshi

2013-01-01

The name Paragonimus westermani (Kerbert, 1878) is commonly applied to members of a species complex that includes the well-known Asian lung fluke of medical and veterinary importance. Unambiguous molecular and morphological evidence showing the presence of a member of the complex in India has recently been published. In the present study we report the occurrence of 2 more members of the P. westermani complex in northeastern (NE) India. Surveys of the freshwater crabs Maydelliatelphusa lugubris in NE India revealed 2 morphologically distinct types of lung fluke metacercariae. Phylogenetic analyses, using DNA sequences from ITS2, 28S and cox1 gene regions indicate that these lung metacercariae belong to P. westermani complex. Type 1 metacercariae have a more basal position within the complex whereas type 2 metacercariae are closely related to the relatively derived forms of P. westermani from NE Asia (Japan, Korea, China) and Vietnam. A third type of metacercaria (type 3), detected in another crab host, Sartoriana spinigera in Assam, was phylogenetically close to P. siamensis, also a member of the P. westermani group. Molecular evidence has demonstrated the existence of 3 genotypes of lung flukes within the Paragonimus westermani complex in NE India. Two of these were previously unknown.

Origin and domestication of papaya Yh chromosome

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VanBuren, Robert; Zeng, Fanchang; Chen, Cuixia; Zhang, Jisen; Wai, Ching Man; Han, Jennifer; Aryal, Rishi; Gschwend, Andrea R.; Wang, Jianping; Na, Jong-Kuk; Huang, Lixian; Zhang, Lingmao; Miao, Wenjing; Gou, Jiqing; Arro, Jie; Guyot, Romain; Moore, Richard C.; Wang, Ming-Li; Zee, Francis; Charlesworth, Deborah; Moore, Paul H.; Yu, Qingyi; Ming, Ray

2015-01-01

Sex in papaya is controlled by a pair of nascent sex chromosomes. Females are XX, and two slightly different Y chromosomes distinguish males (XY) and hermaphrodites (XYh). The hermaphrodite-specific region of the Yh chromosome (HSY) and its X chromosome counterpart were sequenced and analyzed previously. We now report the sequence of the entire male-specific region of the Y (MSY). We used a BAC-by-BAC approach to sequence the MSY and resequence the Y regions of 24 wild males and the Yh regions of 12 cultivated hermaphrodites. The MSY and HSY regions have highly similar gene content and structure, and only 0.4% sequence divergence. The MSY sequences from wild males include three distinct haplotypes, associated with the populations’ geographic locations, but gene flow is detected for other genomic regions. The Yh sequence is highly similar to one Y haplotype (MSY3) found only in wild dioecious populations from the north Pacific region of Costa Rica. The low MSY3-Yh divergence supports the hypothesis that hermaphrodite papaya is a product of human domestication. We estimate that Yh arose only ∼4000 yr ago, well after crop plant domestication in Mesoamerica >6200 yr ago but coinciding with the rise of the Maya civilization. The Yh chromosome has lower nucleotide diversity than the Y, or the genome regions that are not fully sex-linked, consistent with a domestication bottleneck. The identification of the ancestral MSY3 haplotype will expedite investigation of the mutation leading to the domestication of the hermaphrodite Yh chromosome. In turn, this mutation should identify the gene that was affected by the carpel-suppressing mutation that was involved in the evolution of males. PMID:25762551

Meiotic double-strand breaks at the interface of chromosome movement, chromosome remodeling, and reductional division

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Storlazzi, Aurora; Tessé, Sophie; Gargano, Silvana; James, Françoise; Kleckner, Nancy; Zickler, Denise

2003-01-01

Chromosomal processes related to formation and function of meiotic chiasmata have been analyzed in Sordaria macrospora. Double-strand breaks (DSBs), programmed or γ-rays-induced, are found to promote four major events beyond recombination and accompanying synaptonemal complex formation: (1) juxtaposition of homologs from long-distance interactions to close presynaptic coalignment at midleptotene; (2) structural destabilization of chromosomes at leptotene/zygotene, including sister axis separation and fracturing, as revealed in a mutant altered in the conserved, axis-associated cohesin-related protein Spo76/Pds5p; (3) exit from the bouquet stage, with accompanying global chromosome movements, at zygotene/pachytene (bouquet stage exit is further found to be a cell-wide regulatory transition and DSB transesterase Spo11p is suggested to have a new noncatalytic role in this transition); (4) normal occurrence of both meiotic divisions, including normal sister separation. Functional interactions between DSBs and the spo76-1 mutation suggest that Spo76/Pds5p opposes local destabilization of axes at developing chiasma sites and raise the possibility of a regulatory mechanism that directly monitors the presence of chiasmata at metaphase I. Local chromosome remodeling at DSB sites appears to trigger an entire cascade of chromosome movements, morphogenetic changes, and regulatory effects that are superimposed upon a foundation of DSB-independent processes. PMID:14563680

Norrie disease as part of a complex syndrome explained by a submicroscopic deletion of the X chromosome.

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Bleeker-Wagemakers, E M; Zweije-Hofman, I; Gal, A

1988-11-01

A 15-year-old male patient with the typical ocular symptoms of Norrie disease is described. Additionally, he presents severe mental retardation, growth disturbances, hypogonadism, and increased susceptibility to infections. This complex syndrome is apparently segregating through three generations: four other male relatives of the patient were blind from birth and died from recurrent infections between the ages of three to 15 months. The DNA sequence of the DXS7 locus (L1.28 probe), known to be closely linked to the Norrie gene, was not found in the patient's DNA. This result suggests that the more complex clinical picture seen is the result of a deletion of the X chromosome spanning DXS7, the Norrie gene, and several neighbouring loci. A detailed clinical description of the patient is given and compared to that of similar cases.

X-ray induction of mitotic and meiotic chromosome aberrations

International Nuclear Information System (INIS)

Yao, K.T.S.

1980-01-01

In 1964 six pairs of rat kangaroo (Potorous tridactylis) were obtained from Australia. The tissues of these animals were used to initiate cell lines. Since this species has a low chromosome number of six pairs, each pair with its own distinctive morphology, it is particularly favorable for cytogenetic research. In cell cultures derived from the corneal endothelial tissues of one animal there emerged a number of haploid cells. The number of haploid cells in the cultures reached as high as 20% of the total mitotic configurations. The in vitro diploid and haploid mixture cell cultures could be a resemblance or a coincidence to the mixture existence of the diploid primary spermatocytes and the haploid secondary spermatocytes (gametes) in the in vivo testicular tissues of the male animals. It would be interesting to compare reactions of the haploid and diploid cell mixture, either in the cultures or in the testes, to x-ray exposure. Two other studies involving x-ray effects on Chinese hamster oocyte maturation and meiotic chromosomes and the x-ray induction of Chinese hamster spermatocyte meiotic chromosome aberrations have been done in this laboratory. A review of these three studies involving diploid and haploid chromosomes may lead to further research in the x-ray induction of chromosome aberrations

Persistence of radiation-induced chromosome aberrations in a long-term cell culture.

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Duran, Assumpta; Barquinero, Joan Francesc; Caballín, María Rosa; Ribas, Montserrat; Barrios, Leonardo

2009-04-01

The aim of the present study was to evaluate the persistence of chromosome aberrations induced by X rays. FISH painting and mFISH techniques were applied to long-term cultures of irradiated cells. With painting, at 2 Gy the frequency of apparently simple translocations remained almost invariable during all the culture, whereas at 4 Gy a rapid decline was observed between the first and the second samples, followed by a slight decrease until the end of the culture. Apparently simple dicentrics and complex aberrations disappeared after the first sample at 2 and 4 Gy. By mFISH, at 2 Gy the frequency of complete plus one-way translocations remained invariable between the first and last sample, but at 4 Gy a 60% decline was observed. True incomplete simple translocations disappeared at 2 and 4 Gy, indicating that incompleteness could be a factor to consider when the persistence of translocations is analyzed. The analysis by mFISH showed that the frequency of complex aberrations and their complexity increased with dose and tended to disappear in the last sample. Our results indicate that the influence of dose on the decrease in the frequency of simple translocations with time postirradiation cannot be fully explained by the disappearance of true incomplete translocations and complex aberrations. The chromosome involvement was random for radiation-induced exchange aberrations and non-random for total aberrations. Chromosome 7 showed the highest deviations from expected, being less and more involved than expected in the first and last samples, respectively. Some preferential chromosome-chromosome associations were observed, including a coincidence with a cluster from radiogenic chromosome aberrations described in other studies.

Sexual dimorphism in white campion: complex control of carpel number is revealed by Y chromosome deletions

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Lardon, A.; Georgiev, S.; Aghmir, A.; Le Merrer, G.; Negrutiu, I.

1999-01-01

Sexual dimorphism in the dioecious plant white campion (Silene latifolia = Melandrium album) is under the control of two main regions on the Y chromosome. One such region, encoding the gynoecium-suppressing function (GSF), is responsible for the arrest of carpel initiation in male flowers. To generate chromosomal deletions, we used pollen irradiation in male plants to produce hermaphroditic mutants (bsx mutants) in which carpel development was restored. The mutants resulted from alterations in at least two GSF chromosomal regions, one autosomal and one located on the distal half of the (p)-arm of the Y chromosome. The two mutations affected carpel development independently, each mutation showing incomplete penetrance and variegation, albeit at significantly different levels. During successive meiotic generations, a progressive increase in penetrance and a reduction in variegation levels were observed and quantified at the level of the Y-linked GSF (GSF-Y). Possible mechanisms are proposed to explain the behavior of the bsx mutations: epigenetic regulation or/and second-site mutation of modifier genes. In addition, studies on the inheritance of the hermaphroditic trait showed that, unlike wild-type Y chromosomes, deleted Y chromosomes can be transmitted through both the male and the female lines. Altogether, these findings bring experimental support, on the one hand, to the existence on the Y chromosome of genic meiotic drive function(s) and, on the other hand, to models that consider that dioecy evolved through multiple mutation events. As such, the GSF is actually a system containing more than one locus and whose primary component is located on the Y chromosome

Interspecific Y chromosome variation is sufficient to rescue hybrid male sterility and is influenced by the grandparental origin of the chromosomes.

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Araripe, L O; Tao, Y; Lemos, B

2016-06-01

Y chromosomes display population variation within and between species. Co-evolution within populations is expected to produce adaptive interactions between Y chromosomes and the rest of the genome. One consequence is that Y chromosomes from disparate populations could disrupt harmonious interactions between co-evolved genetic elements and result in reduced male fertility, sterility or inviability. Here we address the contribution of 'heterospecific Y chromosomes' to fertility in hybrid males carrying a homozygous region of Drosophila mauritiana introgressed in the Drosophila simulans background. In order to detect Y chromosome-autosome interactions, which may go unnoticed in a single-species background of autosomes, we constructed hybrid genotypes involving three sister species: Drosophila simulans, D. mauritiana, and D. sechellia. These engineered strains varied due to: (i) species origin of the Y chromosome (D. simulans or D. sechellia); (ii) location of the introgressed D. mauritiana segment on the D. simulans third chromosome, and (iii) grandparental genomic background (three genotypes of D. simulans). We find complex interactions between the species origin of the Y chromosome, the identity of the D. mauritiana segment and the grandparental genetic background donating the chromosomes. Unexpectedly, the interaction of the Y chromosome and one segment of D. mauritiana drastically reduced fertility in the presence of Ysim, whereas the fertility is partially rescued by the Y chromosome of D. sechellia when it descends from a specific grandparental genotype. The restoration of fertility occurs in spite of an autosomal and X-linked genome that is mostly of D. simulans origin. These results illustrate the multifactorial basis of genetic interactions involving the Y chromosome. Our study supports the hypothesis that the Y chromosome can contribute significantly to the evolution of reproductive isolation and highlights the conditional manifestation of infertility in

Structure, organization, and sequence of alpha satellite DNA from human chromosome 17: evidence for evolution by unequal crossing-over and an ancestral pentamer repeat shared with the human X chromosome.

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Waye, J S; Willard, H F

1986-09-01

The centromeric regions of all human chromosomes are characterized by distinct subsets of a diverse tandemly repeated DNA family, alpha satellite. On human chromosome 17, the predominant form of alpha satellite is a 2.7-kilobase-pair higher-order repeat unit consisting of 16 alphoid monomers. We present the complete nucleotide sequence of the 16-monomer repeat, which is present in 500 to 1,000 copies per chromosome 17, as well as that of a less abundant 15-monomer repeat, also from chromosome 17. These repeat units were approximately 98% identical in sequence, differing by the exclusion of precisely 1 monomer from the 15-monomer repeat. Homologous unequal crossing-over is suggested as a probable mechanism by which the different repeat lengths on chromosome 17 were generated, and the putative site of such a recombination event is identified. The monomer organization of the chromosome 17 higher-order repeat unit is based, in part, on tandemly repeated pentamers. A similar pentameric suborganization has been previously demonstrated for alpha satellite of the human X chromosome. Despite the organizational similarities, substantial sequence divergence distinguishes these subsets. Hybridization experiments indicate that the chromosome 17 and X subsets are more similar to each other than to the subsets found on several other human chromosomes. We suggest that the chromosome 17 and X alpha satellite subsets may be related components of a larger alphoid subfamily which have evolved from a common ancestral repeat into the contemporary chromosome-specific subsets.

Cloning and comparative mapping of a human chromosome 4-specific alpha satellite DNA sequence

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D' Aiuto, L.; Marzella, R.; Archidiacono, N.; Rocchi, M. (Universita di Bari (Italy)); Antonacci, R. (Instituto Anatomia Umana Normale, Modena (Italy))

1993-11-01

The authors have isolated and characterized two human alphoid DNA clones: p4n1/4 and pZ4.1. Clone p4n1/4 identifies specifically the centromeric region of chromosome 4; pZ4.1 recognizes a subset of alphoid DNA shared by chromosomes 4 and 9. The specificity was determined using fluorescence in situ hybridization experiments on metaphase spreads and Southern blotting analysis of human-hamster somatic cell hybrids. The genomic organization of both subsets was also investigated. Comparative mapping on chimpanzee and gorilla chromosomes was performed. p4n1/4 hybridizes to chimpanzee chromosomes 11 and 13, homologs of human chromosomes 9 and 2q, respectively. On gorilla metaphase spreads, p4n1/4 hybridizes exclusively to the centromeric region of chromosome 19, partially homologous to human chromosome 17. No hybridization signal was detected on chromosome 3 of both chimpanzee and gorilla, in both species homolog of human chromosome 4. Identical comparative mapping results were obtained using pZ4.1 probe, although the latter recognizes an alphoid subset distinct from the one recognized by p4n1/4. The implications of these results in the evolution of centromeric regions of primate chromosomes are discussed. 33 refs., 4 figs.

Suppression of gross chromosomal rearrangements by a new alternative replication factor C complex

International Nuclear Information System (INIS)

Banerjee, Soma; Sikdar, Nilabja; Myung, Kyungjae

2007-01-01

Defects in DNA replication fidelity lead to genomic instability. Gross chromosomal rearrangement (GCR), a type of genomic instability, is highly enhanced by various initial mutations affecting DNA replication. Frequent observations of GCRs in many cancers strongly argue the importance of maintaining high fidelity of DNA replication to suppress carcinogenesis. Recent genome wide screens in Saccharomyces cerevisiae identified a new GCR suppressor gene, ELG1, enhanced level of genome instability gene 1. Its physical interaction with proliferating cell nuclear antigen (PCNA) and complex formation with Rfc2-5p proteins suggest that Elg1 functions to load/unload PCNA onto DNA during a certain DNA metabolism. High level of DNA damage accumulation and enhanced phenotypes with mutations in genes involved in cell cycle checkpoints, homologous recombination (HR), or chromatin assembly in the elg1 strain suggest that Elg1p-Rfc2-5p functions in a fundamental DNA metabolism to suppress genomic instability

Replication termination and chromosome dimer resolution in the archaeon Sulfolobus solfataricus.

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Duggin, Iain G; Dubarry, Nelly; Bell, Stephen D

2011-01-05

Archaea of the genus Sulfolobus have a single-circular chromosome with three replication origins. All three origins fire in every cell in every cell cycle. Thus, three pairs of replication forks converge and terminate in each replication cycle. Here, we report 2D gel analyses of the replication fork fusion zones located between origins. These indicate that replication termination involves stochastic fork collision. In bacteria, replication termination is linked to chromosome dimer resolution, a process that requires the XerC and D recombinases, FtsK and the chromosomal dif site. Sulfolobus encodes a single-Xer homologue and its deletion gave rise to cells with aberrant DNA contents and increased volumes. Identification of the chromosomal dif site that binds Xer in vivo, and biochemical characterization of Xer/dif recombination revealed that, in contrast to bacteria, dif is located outside the fork fusion zones. Therefore, it appears that replication termination and dimer resolution are temporally and spatially distinct processes in Sulfolobus.

Radiation-induced chromosome aberrations and cell killing in normal human fibroblasts and ataxia telangiectasia fibroblasts

International Nuclear Information System (INIS)

Kawata, T.; Saito, M.; Uno, T.; Ito, H.; Shigematsu, N.

2003-01-01

Full text: When cells are held in a non-dividing state (G0) after irradiation, an enhanced survival can be observed compared to that of immediate plating. A change of survival depending on post irradiation condition is known to be repair of potentially lethal damage (RPLD). The effects of confluent holding recovery (24-h incubation following irradiation) on chromosome aberrations in normal human fibroblasts (AG1522) and ataxia telangiectasia fibroblasts (GM02052C) were examined. A chemical-induced premature chromosome condensation (PCC) technique with fluorescent in situ hybridization (FISH) was applied to study chromosome aberrations in G2 and M-phase. Results from cell survival showed that the capacity for potentially lethal damage repair was normal in AG1522 cells but very little in GM02052C cells. The frequency of chromosome aberrations in AG1522 cells decreased when cells were allowed to repair for 24-h. Especially complex type exchanges were found to decrease markedly at high doses (4Gy and 6Gy). However, the frequency of chromosome aberrations including complex type exchanges showed little decrease in GM02052C cells. Confluent holding can effectively reduce chromosome aberrations, especially complex type exchanges in normal cells

Repression of hTERT transcription by the introduction of chromosome 3 into human oral squamous cell carcinoma

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Nishio, Sachiyo [Division of Oral and Maxillofacial Biopathological Surgery, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori, 683-8503 (Japan); Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Yonago, Tottori, 683-8503 (Japan); Ohira, Takahito; Sunamura, Naohiro [Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Yonago, Tottori, 683-8503 (Japan); Oshimura, Mitsuo [Chromosome Engineering Research Center, Tottori University, Yonago, Tottori, 683-8503 (Japan); Ryoke, Kazuo [Division of Oral and Maxillofacial Biopathological Surgery, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori, 683-8503 (Japan); Kugoh, Hiroyuki, E-mail: kugoh@med.tottori-u.ac.jp [Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Yonago, Tottori, 683-8503 (Japan); Chromosome Engineering Research Center, Tottori University, Yonago, Tottori, 683-8503 (Japan)

2015-10-30

Telomerase is a ribonucleoprotein enzyme that maintains telomere length. Telomerase activity is primarily attributed to the expression of telomerase reverse transcriptase (TERT). It has been reported that introduction of an intact human chromosome 3 into the human oral squamous cell carcinoma cell line HSC3 suppresses the tumorigenicity of these cells. However, the mechanisms that regulate tumorigenicity have not been elucidated. To determine whether this reduction in tumorigenicity was accompanied by a reduction in telomerase activity, we investigated the transcriptional activation of TERT in HSC3 microcell hybrid clones with an introduced human chromosome 3 (HSC3#3). HSC#3 cells showed inhibition of hTERT transcription compared to that of the parental HSC3 cells. Furthermore, cell fusion experiments showed that hybrids of HSC3 cells and cells of the RCC23 renal carcinoma cell line, which also exhibits suppression of TERT transcription by the introduction of human chromosome 3, also displayed suppressed TERT transcription. These results suggested that human chromosome 3 may carry functionally distinct, additional TERT repressor genes. - Highlights: • hTERT mRNA expression level decreased in the chromosome 3 introduced HSC3 clones. • hTERT mRNA expression level was tend to suppressed in HSC3 and RCC23 hybrid cells. • We provide evidence that human chromosome 3 carries at least two distinct hTERT regulatory factors.

Repression of hTERT transcription by the introduction of chromosome 3 into human oral squamous cell carcinoma

International Nuclear Information System (INIS)

Nishio, Sachiyo; Ohira, Takahito; Sunamura, Naohiro; Oshimura, Mitsuo; Ryoke, Kazuo; Kugoh, Hiroyuki

2015-01-01

Telomerase is a ribonucleoprotein enzyme that maintains telomere length. Telomerase activity is primarily attributed to the expression of telomerase reverse transcriptase (TERT). It has been reported that introduction of an intact human chromosome 3 into the human oral squamous cell carcinoma cell line HSC3 suppresses the tumorigenicity of these cells. However, the mechanisms that regulate tumorigenicity have not been elucidated. To determine whether this reduction in tumorigenicity was accompanied by a reduction in telomerase activity, we investigated the transcriptional activation of TERT in HSC3 microcell hybrid clones with an introduced human chromosome 3 (HSC3#3). HSC#3 cells showed inhibition of hTERT transcription compared to that of the parental HSC3 cells. Furthermore, cell fusion experiments showed that hybrids of HSC3 cells and cells of the RCC23 renal carcinoma cell line, which also exhibits suppression of TERT transcription by the introduction of human chromosome 3, also displayed suppressed TERT transcription. These results suggested that human chromosome 3 may carry functionally distinct, additional TERT repressor genes. - Highlights: • hTERT mRNA expression level decreased in the chromosome 3 introduced HSC3 clones. • hTERT mRNA expression level was tend to suppressed in HSC3 and RCC23 hybrid cells. • We provide evidence that human chromosome 3 carries at least two distinct hTERT regulatory factors.

A minimal number of MELT repeats supports all functions of KNL1 in chromosome segregation

DEFF Research Database (Denmark)

Zhang, Gang; Lischetti, Tiziana; Nilsson, Jakob

2013-01-01

The Bub1-Bub3 and BubR1-Bub3 checkpoint complexes, or the Bubs, contribute to the accurate segregation of chromosomes during mitosis by promoting chromosome bi-orientation and halting exit from mitosis if this fails. The complexes associate with kinetochores during mitosis, which is required...

The genome of Nectria haematococca: contribution of supernumerary chromosomes to gene expansion.

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Jeffrey J Coleman

2009-08-01

Full Text Available The ascomycetous fungus Nectria haematococca, (asexual name Fusarium solani, is a member of a group of >50 species known as the "Fusarium solani species complex". Members of this complex have diverse biological properties including the ability to cause disease on >100 genera of plants and opportunistic infections in humans. The current research analyzed the most extensively studied member of this complex, N. haematococca mating population VI (MPVI. Several genes controlling the ability of individual isolates of this species to colonize specific habitats are located on supernumerary chromosomes. Optical mapping revealed that the sequenced isolate has 17 chromosomes ranging from 530 kb to 6.52 Mb and that the physical size of the genome, 54.43 Mb, and the number of predicted genes, 15,707, are among the largest reported for ascomycetes. Two classes of genes have contributed to gene expansion: specific genes that are not found in other fungi including its closest sequenced relative, Fusarium graminearum; and genes that commonly occur as single copies in other fungi but are present as multiple copies in N. haematococca MPVI. Some of these additional genes appear to have resulted from gene duplication events, while others may have been acquired through horizontal gene transfer. The supernumerary nature of three chromosomes, 14, 15, and 17, was confirmed by their absence in pulsed field gel electrophoresis experiments of some isolates and by demonstrating that these isolates lacked chromosome-specific sequences found on the ends of these chromosomes. These supernumerary chromosomes contain more repeat sequences, are enriched in unique and duplicated genes, and have a lower G+C content in comparison to the other chromosomes. Although the origin(s of the extra genes and the supernumerary chromosomes is not known, the gene expansion and its large genome size are consistent with this species' diverse range of habitats. Furthermore, the presence of unique

The genome of Nectria haematococca: contribution of supernumerary chromosomes to gene expansion

Energy Technology Data Exchange (ETDEWEB)

Coleman, J.J.; Rounsley, S.D.; Rodriguez-Carres, M.; Kuo, A.; Wasmann, C.c.; Grimwood, J.; Schmutz, J.; Taga, M.; White, G.J.; Zhuo, S.; Schwartz, D.C.; Freitag, M.; Ma, L.-J.; Danchin, E.G.J.; Henrissat, B.; Cutinho, P.M.; Nelson, D.R.; Straney, D.; Napoli, C.A.; Baker, B.M.; Gribskov, M.; Rep, M.; Kroken, S.; Molnar, I.; Rensing, C.; Kennell, J.C.; Zamora, J.; Farman, M.L.; Selker, E.U.; Salamov, A.; Shapiro, H.; Pangilinan, J.; Lindquist, E.; Lamers, C.; Grigoriev, I.V.; Geiser, D.M.; Covert, S.F.; Temporini, S.; VanEtten, H.D.

2009-04-20

The ascomycetous fungus Nectria haematococca, (asexual name Fusarium solani), is a member of a group of .50 species known as the"Fusarium solani species complex". Members of this complex have diverse biological properties including the ability to cause disease on .100 genera of plants and opportunistic infections in humans. The current research analyzed the most extensively studied member of this complex, N. haematococca mating population VI (MPVI). Several genes controlling the ability of individual isolates of this species to colonize specific habitats are located on supernumerary chromosomes. Optical mapping revealed that the sequenced isolate has 17 chromosomes ranging from 530 kb to 6.52 Mb and that the physical size of the genome, 54.43 Mb, and the number of predicted genes, 15,707, are among the largest reported for ascomycetes. Two classes of genes have contributed to gene expansion: specific genes that are not found in other fungi including its closest sequenced relative, Fusarium graminearum; and genes that commonly occur as single copies in other fungi but are present as multiple copies in N. haematococca MPVI. Some of these additional genes appear to have resulted from gene duplication events, while others may have been acquired through horizontal gene transfer. The supernumerary nature of three chromosomes, 14, 15, and 17, was confirmed by their absence in pulsed field gel electrophoresis experiments of some isolates and by demonstrating that these isolates lacked chromosome-specific sequences found on the ends of these chromosomes. These supernumerary chromosomes contain more repeat sequences, are enriched in unique and duplicated genes, and have a lower G+C content in comparison to the other chromosomes. Although the origin(s) of the extra genes and the supernumerary chromosomes is not known, the gene expansion and its large genome size are consistent with this species' diverse range of habitats. Furthermore, the presence of unique genes on

Structural rearrangements of chromosome 15 satellites resulting in Prader-Willi syndrome suggest a complex mechanism for uniparental disomy

Energy Technology Data Exchange (ETDEWEB)

Toth-Fijel, S.; Gunter, K.; Olson, S. [Oregon Health Sciences Univ., Portland, OR (United States)] [and others

1994-09-01

We report two cases of PWS in which there was abnormal meiosis I segregation of chromosome 15 following a rare translocation event between the heteromorphic satellite regions of chromosomes 14 and 15 and an apparent meiotic recombination in the unstable region of 15q11.2. PWS and normal appearing chromosomes in case one prompted a chromosome 15 origin analysis. PCR analysis indicated maternal isodisomy for the long arm of chromosome. However, only one chromosome 15 had short arm heteromorphisms consistent with either paternal or maternal inheritance. VNTR DNA analysis and heteromorphism data suggest that a maternal de novo translocation between chromosome 14 and 15 occurred prior to meiosis I. This was followed by recombination between D15Z1 and D15S11 and subsequent meiosis I nondisjunction. Proband and maternal karyotype display a distamycin A-DAPI positive region on the chromosome 14 homolog involved in the translocation. Fluorescent in situ hybridization (FISH) analyses of ONCOR probes D15S11, SNRPN, D15S11 and GABRB 3 were normal, consistent with the molecular data. Case two received a Robertsonian translocation t(14;15)(p13;p13) of maternal origin. Chromosome analysis revealed a meiosis I error producing UPD. FISH analysis of the proband and parents showed normal hybridization of ONCOR probes D15Z1, D15S11, SNRPN, D15S10 and GABRB3. In both cases the PWS probands received a structurally altered chromosome 15 that had rearranged with chromosome 14 prior to meiosis. If proper meiotic segregation is dependent on the resolution of chiasmata and/or the binding to chromosome-specific spindle fibers, then it may be possible that rearrangements of pericentric or unstable regions of the genome disrupt normal disjunction and lead to uniparental disomy.

The Aurora B kinase in chromosome biorientation and spindle checkpoint signalling

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Veronica eKrenn

2015-10-01

Full Text Available Aurora B, a member of the Aurora family of serine/threonine protein kinases, is a key player in chromosome segregation. As part of a macromolecular complex known as the chromosome passenger complex, Aurora B concentrates early during mitosis in the proximity of centromeres and kinetochores, the sites of attachment of chromosomes to spindle microtubules. There, it contributes to a number of processes that impart fidelity to cell division, including kinetochore stabilization, kinetochore-microtubule attachment, and the regulation of a surveillance mechanism named the spindle assembly checkpoint. In the regulation of these processes, Aurora B is the fulcrum of a remarkably complex network of interactions that feed back on its localization and activation state. In this review we discuss the multiple roles of Aurora B during mitosis, focusing in particular on its role at centromeres and kinetochores. Many details of the network of interactions at these locations remain poorly understood, and we focus here on several crucial outstanding questions.

Three-dimensional super-resolution microscopy of the inactive X chromosome territory reveals a collapse of its active nuclear compartment harboring distinct Xist RNA foci.

Science.gov (United States)

Smeets, Daniel; Markaki, Yolanda; Schmid, Volker J; Kraus, Felix; Tattermusch, Anna; Cerase, Andrea; Sterr, Michael; Fiedler, Susanne; Demmerle, Justin; Popken, Jens; Leonhardt, Heinrich; Brockdorff, Neil; Cremer, Thomas; Schermelleh, Lothar; Cremer, Marion

2014-01-01

A Xist RNA decorated Barr body is the structural hallmark of the compacted inactive X territory in female mammals. Using super-resolution three-dimensional structured illumination microscopy (3D-SIM) and quantitative image analysis, we compared its ultrastructure with active chromosome territories (CTs) in human and mouse somatic cells, and explored the spatio-temporal process of Barr body formation at onset of inactivation in early differentiating mouse embryonic stem cells (ESCs). We demonstrate that all CTs are composed of structurally linked chromatin domain clusters (CDCs). In active CTs the periphery of CDCs harbors low-density chromatin enriched with transcriptionally competent markers, called the perichromatin region (PR). The PR borders on a contiguous channel system, the interchromatin compartment (IC), which starts at nuclear pores and pervades CTs. We propose that the PR and macromolecular complexes in IC channels together form the transcriptionally permissive active nuclear compartment (ANC). The Barr body differs from active CTs by a partially collapsed ANC with CDCs coming significantly closer together, although a rudimentary IC channel system connected to nuclear pores is maintained. Distinct Xist RNA foci, closely adjacent to the nuclear matrix scaffold attachment factor-A (SAF-A) localize throughout Xi along the rudimentary ANC. In early differentiating ESCs initial Xist RNA spreading precedes Barr body formation, which occurs concurrent with the subsequent exclusion of RNA polymerase II (RNAP II). Induction of a transgenic autosomal Xist RNA in a male ESC triggers the formation of an 'autosomal Barr body' with less compacted chromatin and incomplete RNAP II exclusion. 3D-SIM provides experimental evidence for profound differences between the functional architecture of transcriptionally active CTs and the Barr body. Basic structural features of CT organization such as CDCs and IC channels are however still recognized, arguing against a uniform

[Mechanistic modelling allows to assess pathways of DNA lesion interactions underlying chromosome aberration formation].

Science.gov (United States)

Eĭdel'man, Iu A; Slanina, S V; Sal'nikov, I V; Andreev, S G

2012-12-01

The knowledge of radiation-induced chromosomal aberration (CA) mechanisms is required in many fields of radiation genetics, radiation biology, biodosimetry, etc. However, these mechanisms are yet to be quantitatively characterised. One of the reasons is that the relationships between primary lesions of DNA/chromatin/chromosomes and dose-response curves for CA are unknown because the pathways of lesion interactions in an interphase nucleus are currently inaccessible for direct experimental observation. This article aims for the comparative analysis of two principally different scenarios of formation of simple and complex interchromosomal exchange aberrations: by lesion interactions at chromosome territories' surface vs. in the whole space of the nucleus. The analysis was based on quantitative mechanistic modelling of different levels of structures and processes involved in CA formation: chromosome structure in an interphase nucleus, induction, repair and interactions of DNA lesions. It was shown that the restricted diffusion of chromosomal loci, predicted by computational modelling of chromosome organization, results in lesion interactions in the whole space of the nucleus being impossible. At the same time, predicted features of subchromosomal dynamics agrees well with in vivo observations and does not contradict the mechanism of CA formation at the surface of chromosome territories. On the other hand, the "surface mechanism" of CA formation, despite having certain qualities, proved to be insufficient to explain high frequency of complex exchange aberrations observed by mFISH technique. The alternative mechanism, CA formation on nuclear centres is expected to be sufficient to explain frequent complex exchanges.

Human SGT interacts with Bag-6/Bat-3/Scythe and cells with reduced levels of either protein display persistence of few misaligned chromosomes and mitotic arrest

International Nuclear Information System (INIS)

Winnefeld, Marc; Grewenig, Annabel; Schnoelzer, Martina; Spring, Herbert; Knoch, Tobias A.; Gan, Eugene C.; Rommelaere, Jean; Cziepluch, Celina

2006-01-01

The human small glutamine-rich TPR-containing protein (hSGT) is essential for cell division since RNA-interference-mediated strong reduction of hSGT protein levels causes mitotic arrest (M. Winnefeld, J. Rommelaere, and C. Cziepluch, The human small glutamine-rich TPR-containing protein is required for progress through cell division, Exp. Cell Res. 293 (2004), 43-57). Analysis of HeLa cells expressing a histone 2A-YFP fusion protein revealed the continuous presence of few mislocalized chromosomes close to the spindle poles as possible cause for hSGT depletion-dependent prometaphase arrest. Cells unable to rescue these mislocalized chromosomes into the metaphase plate died at this stage through apoptosis. In order to address hSGT function at the molecular level, mass spectrometry analysis of proteins which co-immunoprecipitated with Flag-tagged hSGT was performed. Thereby, Hsp70 and Bag-6/Bat-3/Scythe were identified as novel hSGT interaction partners while interaction with Hsc70 was confirmed. Results obtained with truncated versions of the hSGT protein revealed that Bag-6/Bat-3/Scythe and Hsp70 or Hsc70 were independently able to form complexes with hSGT. Interaction of hSGT with Hsc70, Hsp70 or Bag-6/Bat-3/Scythe was demonstrated in prometaphase, thereby suggesting a possible role for complexes containing hSGT and distinct (co)-chaperones during mitosis. Finally, cells from populations with reduced levels of Bag-6/Bat-3/Scythe also displayed persistence of mislocalized chromosomes and mitotic arrest, which strongly indicated that hSGT-Bag-6/Bat-3/Scythe complexes could be directly or indirectly required for complete chromosome congression

Gametocidal chromosomes enhancing chromosome aberration in common wheat induced by 5-azacytidine.

Science.gov (United States)

Su, W-Y; Cong, W-W; Shu, Y-J; Wang, D; Xu, G-H; Guo, C-H

2013-07-08

The gametocidal (Gc) chromosome from Aegilops spp induces chromosome mutation, which is introduced into common wheat as a tool of chromosome manipulation for genetic improvement. The Gc chromosome functions similar to a restriction-modification system in bacteria, in which DNA methylation is an important regulator. We treated root tips of wheat carrying Gc chromosomes with the hypomethylation agent 5-azacytidine; chromosome breakage and micronuclei were observed in these root tips. The frequency of aberrations differed in wheat containing different Gc chromosomes, suggesting different functions inducing chromosome breakage. Gc chromosome 3C caused the greatest degree of chromosome aberration, while Gc chromosome 3C(SAT) and 2C caused only slight chromosome aberration. Gc chromosome 3C induced different degrees of chromosome aberration in wheat varieties Triticum aestivum var. Chinese Spring and Norin 26, demonstrating an inhibition function in common wheat.

Chromosomes and their meiotic behaviour in two species of Dieuches Dohrn, 1860 (Heteroptera: Lygaeidae: Rhyparochromini

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Harbhajan Kaur

2009-08-01

Full Text Available The Lygaeidae (Heteroptera are a large and diverse family in which the male diploid chromosomal complement ranges from 10 to 30. Diploid numbers of 14 and 16 are taken as two modal numbers of the family. The Rhyparochrominae, one of the largest subfamilies of the Lygaeidae, are known to be heterogeneous both cytologically and morphologically. Available data on the tribe Rhyparochromini reveal that all species are characterized by the presence of a pair of microchromosomes (m-chromosomes and have an XY/XX (♂/♀ sex chromosome determining system. Dieuches coloratus (Distant, 1909 and D. insignis (Distant, 1918 belonging to Rhyparochromini, have 2n=14=10A+2m+XY and 2n=12=8A+2m+XY respectively. Both the species are similar inone pair of distinctly large autosomes in their chromosome complements. The metaphase plate arrangement of autosomes, sex chromosomes and m-chromosomes in D. coloratus is similar to the common condition observed in the tribe Rhyparochromini. In D. insignis, however, the arrangement is different. Here, metaphase I is usual in showing peripheral position of autosomes and central position of sex chromosomes and m-chromosomes. At metaphase II, however, autosomes, sex chromosomes and m-chromosomes are peripherally placed, an arrangement, which is not reported earlier in the tribe Rhyparochromini.

Common and distinctive localization patterns of Crumbs polarity complex proteins in the mammalian eye.

Science.gov (United States)

Kim, Jin Young; Song, Ji Yun; Karnam, Santi; Park, Jun Young; Lee, Jamie J H; Kim, Seonhee; Cho, Seo-Hee

2015-01-01

Crumbs polarity complex proteins are essential for cellular and tissue polarity, and for adhesion of epithelial cells. In epithelial tissues deletion of any of three core proteins disrupts localization of the other proteins, indicating structural and functional interdependence among core components. Despite previous studies of function and co-localization that illustrated the properties that these proteins share, it is not known whether an individual component of the complex plays a distinct role in a unique cellular and developmental context. In order to investigate this question, we primarily used confocal imaging to determine the expression and subcellular localization of the core Crumbs polarity complex proteins during ocular development. Here we show that in developing ocular tissues core Crumbs polarity complex proteins, Crb, Pals1 and Patj, generally appear in an overlapping pattern with some exceptions. All three core complex proteins localize to the apical junction of the retinal and lens epithelia. Pals1 is also localized in the Golgi of the retinal cells and Patj localizes to the nuclei of the apically located subset of progenitor cells. These findings suggest that core Crumbs polarity complex proteins exert common and independent functions depending on cellular context. Copyright © 2015 Elsevier B.V. All rights reserved.

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...... A + B). Pregnant women 35 years of age, women who previously had a chromosomally abnormal child, families with translocation carriers or other heritable chromosomal disease, families where the father was 50 years or more and women in families with a history of Down's syndrome (group A), were compared...... 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...

fMRI Reveals Distinct CNS Processing during Symptomatic and Recovered Complex Regional Pain Syndrome in Children

Science.gov (United States)

Lebel, A.; Becerra, L.; Wallin, D.; Moulton, E. A.; Morris, S.; Pendse, G.; Jasciewicz, J.; Stein, M.; Aiello-Lammens, M.; Grant, E.; Berde, C.; Borsook, D.

2008-01-01

Complex regional pain syndrome (CRPS) in paediatric patients is clinically distinct from the adult condition in which there is often complete resolution of its signs and symptoms within several months to a few years. The ability to compare the symptomatic and asymptomatic condition in the same individuals makes this population interesting for the…

Microsatellite organization in the grasshopper Abracris flavolineata (Orthoptera: Acrididae revealed by FISH mapping: remarkable spreading in the A and B chromosomes.

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Diogo Milani

Full Text Available With the aim of acquiring deeper knowledge about repetitive DNAs chromosomal organization in grasshoppers, we used fluorescent in situ hybridization (FISH to map the distribution of 16 microsatellite repeats, including mono-, di-, tri- and tetra-nucleotides, in the chromosomes of the species Abracris flavolineata (Acrididae, which harbors B chromosome. FISH revealed two main patterns: (i exclusively scattered signals, and (ii scattered and specific signals, forming evident blocks. The enrichment was observed in both euchromatic and heterochromatic areas and only the motif (C30 was absent in heterochromatin. The A and B chromosomes were enriched with all the elements that were mapped, being observed in the B chromosome more distinctive blocks for (GA15 and (GAG10. For A complement distinctive blocks were noticed for (A30, (CA15, (CG15, (GA15, (CAC10, (CAA10, (CGG10, (GAA10, (GAC10 and (GATA8. These results revealed an intense spreading of microsatellites in the A. flavolineata genome that was independent of the A+T or G+C enrichment in the repeats. The data indicate that the microsatellites compose the B chromosome and could be involved in the evolution of this element in this species, although no specific relationship with any A chromosome was observed to discuss about its origin. The systematic analysis presented here contributes to the knowledge of repetitive DNA chromosomal organization among grasshoppers including the B chromosomes.

Classic theory for chromosome rearrangements with spatially restricted volume for broken ends interaction

International Nuclear Information System (INIS)

Omel'yanchuk, L.V.

1997-01-01

D. Lea classic theory for chromosomal rearrangements formation was modified to account for local interaction of broken chromosome ends. This assumption makes it possible to drastically improve coincidence of the theory and experiment in the case of complex rearrangements

Construction of BAC Libraries from Flow-Sorted Chromosomes.

Science.gov (United States)

Šafář, Jan; Šimková, Hana; Doležel, Jaroslav

2016-01-01

Cloned DNA libraries in bacterial artificial chromosome (BAC) are the most widely used form of large-insert DNA libraries. BAC libraries are typically represented by ordered clones derived from genomic DNA of a particular organism. In the case of large eukaryotic genomes, whole-genome libraries consist of a hundred thousand to a million clones, which make their handling and screening a daunting task. The labor and cost of working with whole-genome libraries can be greatly reduced by constructing a library derived from a smaller part of the genome. Here we describe construction of BAC libraries from mitotic chromosomes purified by flow cytometric sorting. Chromosome-specific BAC libraries facilitate positional gene cloning, physical mapping, and sequencing in complex plant genomes.

FISHIS: fluorescence in situ hybridization in suspension and chromosome flow sorting made easy.

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Debora Giorgi

Full Text Available The large size and complex polyploid nature of many genomes has often hampered genomics development, as is the case for several plants of high agronomic value. Isolating single chromosomes or chromosome arms via flow sorting offers a clue to resolve such complexity by focusing sequencing to a discrete and self-consistent part of the whole genome. The occurrence of sufficient differences in the size and or base-pair composition of the individual chromosomes, which is uncommon in plants, is critical for the success of flow sorting. We overcome this limitation by developing a robust method for labeling isolated chromosomes, named Fluorescent In situ Hybridization In suspension (FISHIS. FISHIS employs fluorescently labeled synthetic repetitive DNA probes, which are hybridized, in a wash-less procedure, to chromosomes in suspension following DNA alkaline denaturation. All typical A, B and D genomes of wheat, as well as individual chromosomes from pasta (T. durum L. and bread (T. aestivum L. wheat, were flow-sorted, after FISHIS, at high purity. For the first time in eukaryotes, each individual chromosome of a diploid organism, Dasypyrum villosum (L. Candargy, was flow-sorted regardless of its size or base-pair related content. FISHIS-based chromosome sorting is a powerful and innovative flow cytogenetic tool which can develop new genomic resources from each plant species, where microsatellite DNA probes are available and high quality chromosome suspensions could be produced. The joining of FISHIS labeling and flow sorting with the Next Generation Sequencing methodology will enforce genomics for more species, and by this mightier chromosome approach it will be possible to increase our knowledge about structure, evolution and function of plant genome to be used for crop improvement. It is also anticipated that this technique could contribute to analyze and sort animal chromosomes with peculiar cytogenetic abnormalities, such as copy number variations

FISHIS: fluorescence in situ hybridization in suspension and chromosome flow sorting made easy.

Science.gov (United States)

Giorgi, Debora; Farina, Anna; Grosso, Valentina; Gennaro, Andrea; Ceoloni, Carla; Lucretti, Sergio

2013-01-01

The large size and complex polyploid nature of many genomes has often hampered genomics development, as is the case for several plants of high agronomic value. Isolating single chromosomes or chromosome arms via flow sorting offers a clue to resolve such complexity by focusing sequencing to a discrete and self-consistent part of the whole genome. The occurrence of sufficient differences in the size and or base-pair composition of the individual chromosomes, which is uncommon in plants, is critical for the success of flow sorting. We overcome this limitation by developing a robust method for labeling isolated chromosomes, named Fluorescent In situ Hybridization In suspension (FISHIS). FISHIS employs fluorescently labeled synthetic repetitive DNA probes, which are hybridized, in a wash-less procedure, to chromosomes in suspension following DNA alkaline denaturation. All typical A, B and D genomes of wheat, as well as individual chromosomes from pasta (T. durum L.) and bread (T. aestivum L.) wheat, were flow-sorted, after FISHIS, at high purity. For the first time in eukaryotes, each individual chromosome of a diploid organism, Dasypyrum villosum (L.) Candargy, was flow-sorted regardless of its size or base-pair related content. FISHIS-based chromosome sorting is a powerful and innovative flow cytogenetic tool which can develop new genomic resources from each plant species, where microsatellite DNA probes are available and high quality chromosome suspensions could be produced. The joining of FISHIS labeling and flow sorting with the Next Generation Sequencing methodology will enforce genomics for more species, and by this mightier chromosome approach it will be possible to increase our knowledge about structure, evolution and function of plant genome to be used for crop improvement. It is also anticipated that this technique could contribute to analyze and sort animal chromosomes with peculiar cytogenetic abnormalities, such as copy number variations or cytogenetic

Karyotype Evolution in Birds: from Conventional Staining to Chromosome Painting

OpenAIRE

Ferguson-Smith, Malcolm

2018-01-01

In this work we performed comparative chromosome painting using probes from Gallus gallus (GGA) Linnaeus, 1758 and Leucopternis albicollis (LAL) Latham, 1790 in Synallaxis frontalis Pelzeln, 1859 (Passeriformes, Furnariidae), an exclusively Neotropical species, in order to analyze whether the complex pattern of intrachromosomal rearrangements (paracentric and pericentric inversions) proposed for Oscines and Suboscines is shared with more basal species. S. frontalis has 82 chromosomes, similar...

Chronic lymphocytic leukemia-associated chromosomal abnormalities and miRNA deregulation

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Kiefer Y

2012-03-01

Full Text Available Yvonne Kiefer1, Christoph Schulte2, Markus Tiemann2, Joern Bullerdiek11Center for Human Genetics, University of Bremen, Bremen, Germany; 2Hematopathology Hamburg, Hamburg, GermanyAbstract: Chronic lymphocytic leukemia is the most common leukemia in adults. By cytogenetic investigations major subgroups of the disease can be identified that reflect different routes of tumor development. Of these chromosomal deviations, trisomy 12 and deletions of parts of either the long arm of chromosome 13, the long arm of chromosome 11, or the short arm of chromosome 17 are most commonly detected. In some of these aberrations the molecular target has been identified as eg, ataxia telangiectasia mutated (ATM in case of deletions of chromosomal region 11q22~23 and the genes encoding microRNAs miR-15a/16-1 as likely targets of deletions of chromosomal band 13q14.3. Of note, these aberrations do not characterize independent subgroups but often coexist within the metaphases of one tumor. Generally, complex aberrations are associated with a worse prognosis than simple karyotypic alterations. Due to smaller sizes of the missing segment the detection of recurrent deletions is not always possible by means of classical cytogenetics but requires more advanced techniques as in particular fluorescence in situ hybridization (FISH. Nevertheless, at this time it is not recommended to replace classical cytogenetics by FISH because this would miss additional information given by complex or secondary karyotypic alterations. However, the results of cytogenetic analyses allow the stratification of prognostic and predictive groups of the disease. Of these, the group characterized by deletions involving TP53 is clinically most relevant. In the future refined methods as eg, array-based comparative genomic hybridization will supplement the existing techniques to characterize CLL. Keywords: chronic lymphocytic leukemia, chromosomal abnormality, miRNA deregulation

Inter-chromosomal heterogeneity in the formation of radiation induced chromosomal aberrations

International Nuclear Information System (INIS)

Natarajan, A.T.; Vermeulen, S.; Boei, J.J.W.A.

1997-01-01

It is generally assumed that radiation induced chromosomal lesions are distributed randomly and repaired randomly among the genome. Recent studies using fluorescent in situ hybridization (FISH) and chromosome specific DNA libraries indicate that some chromosomes are more sensitive for radiation induced aberration formation than others. Chromosome No. 4 in human and chromosome No. 8 in Chinese hamster have been found to involve more in exchange aberrations than others, when calculated on the basis of their DNA content. Painting with arm specific chromosome libraries indicate that the frequencies of radiation induced intra-chromosome exchanges (i.e., between the arms of a chromosome, such as centric rings and inversions) are far in excess than one would expect on the basis of the frequencies of observed inter-chromosomal exchanges. The possible factors leading to the observed heterogeneity will be discussed

Stable X chromosome inactivation involves the PRC1 Polycomb complex and requires histone MACROH2A1 and the CULLIN3/SPOP ubiquitin E3 ligase

DEFF Research Database (Denmark)

Hernández-Muñoz, Inmaculada; Lund, Anders H; van der Stoop, Petra

2005-01-01

X inactivation involves the stable silencing of one of the two X chromosomes in XX female mammals. Initiation of this process occurs during early development and involves Xist (X-inactive-specific transcript) RNA coating and the recruitment of Polycomb repressive complex (PRC) 2 and PRC1 proteins...

Chromosome aberrations in F1 from irradiated male mice studied by their synaptonemal complexes

International Nuclear Information System (INIS)

Kalikinskaya, E.I.; Kolomiets, O.L.; Shevchenko, V.A.; Bogdanov, Yu.F.

1986-01-01

Possible implications of surface-spread synaptonemal complex (SC) karyotyping in analysing the causes of sterility of F 1 from irradiated male mice are demonstrated in this work. After irradiation by 137 Cs γ-rays at a dose of 5 Gy the males were mated to unirradiated females and genetic analysis of fertility in the F 1 progeny was carried out. Males with abnormal fertility were examined for the presence of chromosome aberrations in diakinesis-metaphase I and in pachytene by the method of surface-spread SC karyotyping. In most cases, SC karyotyping provides additional information and permits the detection and analysis of aberrations that are not revealed in diakinesis. Two reciprocal translocations, one X autosomal and one nonreciprocal translocation were discovered in five F 1 males studied. It is concluded that the method is efficient in detecting translocations in pachytene in partially fertile F 1 hybrids of irradiated and normal mice. (orig.)

Transmission of chromosomal and instability via a chromosome irradiated with ionizing radiation

International Nuclear Information System (INIS)

Kodama, Seiji; Tanabe, Masateru; Shiraishi, Kazunori; Oshimura, Mitsuo

2010-01-01

We examined the stability of the transferred chromosome in 5 and 12 microcell hybrids including unirradiated human chromosomes 6 and 8, respectively, and 6 and 19 microcell hybrids including 4 Gy-irradiated human chromosomes 6 and 8, respectively. The transferred chromosome was structurally stable in most microcell hybrids transferred with the unirradiated chromosomes 6 and 8. In contrast, the 4 Gy-irradiated human chromosomes were unstable in 3 out of 6 hybrids (50%) with chromosome 6 and 3 out of 19 hybrids (16%) with chromosome 8, showing multiple aberrations in high frequencies (35∼98%). To know the cause of delayed chromosomal instability, intrachromosomal rearrangements of the human chromosome is investigated by subtelomere FISH in 17 microcell hybrids transferred with chromosomes 6 and 8. We found frequent intrachromosomal in 7 microcell hybrids (41%). However, no clear correlation was observed between the intrachromosomal rearrangements and the induction of delayed chromosomal instability by ionizing radiation

Introducing the Algerian mitochondrial DNA and Y-chromosome profiles into the North African landscape.

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Asmahan Bekada

Full Text Available North Africa is considered a distinct geographic and ethnic entity within Africa. Although modern humans originated in this Continent, studies of mitochondrial DNA (mtDNA and Y-chromosome genealogical markers provide evidence that the North African gene pool has been shaped by the back-migration of several Eurasian lineages in Paleolithic and Neolithic times. More recent influences from sub-Saharan Africa and Mediterranean Europe are also evident. The presence of East-West and North-South haplogroup frequency gradients strongly reinforces the genetic complexity of this region. However, this genetic scenario is beset with a notable gap, which is the lack of consistent information for Algeria, the largest country in the Maghreb. To fill this gap, we analyzed a sample of 240 unrelated subjects from a northwest Algeria cosmopolitan population using mtDNA sequences and Y-chromosome biallelic polymorphisms, focusing on the fine dissection of haplogroups E and R, which are the most prevalent in North Africa and Europe respectively. The Eurasian component in Algeria reached 80% for mtDNA and 90% for Y-chromosome. However, within them, the North African genetic component for mtDNA (U6 and M1; 20% is significantly smaller than the paternal (E-M81 and E-V65; 70%. The unexpected presence of the European-derived Y-chromosome lineages R-M412, R-S116, R-U152 and R-M529 in Algeria and the rest of the Maghreb could be the counterparts of the mtDNA H1, H3 and V subgroups, pointing to direct maritime contacts between the European and North African sides of the western Mediterranean. Female influx of sub-Saharan Africans into Algeria (20% is also significantly greater than the male (10%. In spite of these sexual asymmetries, the Algerian uniparental profiles faithfully correlate between each other and with the geography.

Mitotic chromosome structure

International Nuclear Information System (INIS)

Heermann, Dieter W.

2012-01-01

Mounting evidence is compiling linking the physical organizational structure of chromosomes and the nuclear structure to biological function. At the base of the physical organizational structure of both is the concept of loop formation. This implies that physical proximity within chromosomes is provided for otherwise distal genomic regions and thus hierarchically organizing the chromosomes. Together with entropy many experimental observations can be explained with these two concepts. Among the observations that can be explained are the measured physical extent of the chromosomes, their shape, mechanical behavior, the segregation into territories (chromosomal and territories within chromosomes), the results from chromosome conformation capture experiments, as well as linking gene expression to structural organization.

Mitotic chromosome structure

Energy Technology Data Exchange (ETDEWEB)

Heermann, Dieter W., E-mail: heermann@tphys.uni-heidelberg.de

2012-07-15

Mounting evidence is compiling linking the physical organizational structure of chromosomes and the nuclear structure to biological function. At the base of the physical organizational structure of both is the concept of loop formation. This implies that physical proximity within chromosomes is provided for otherwise distal genomic regions and thus hierarchically organizing the chromosomes. Together with entropy many experimental observations can be explained with these two concepts. Among the observations that can be explained are the measured physical extent of the chromosomes, their shape, mechanical behavior, the segregation into territories (chromosomal and territories within chromosomes), the results from chromosome conformation capture experiments, as well as linking gene expression to structural organization.

Purifying Selection Maintains Dosage-Sensitive Genes during Degeneration of the Threespine Stickleback Y Chromosome

Science.gov (United States)

White, Michael A.; Kitano, Jun; Peichel, Catherine L.

2015-01-01

Sex chromosomes are subject to unique evolutionary forces that cause suppression of recombination, leading to sequence degeneration and the formation of heteromorphic chromosome pairs (i.e., XY or ZW). Although progress has been made in characterizing the outcomes of these evolutionary processes on vertebrate sex chromosomes, it is still unclear how recombination suppression and sequence divergence typically occur and how gene dosage imbalances are resolved in the heterogametic sex. The threespine stickleback fish (Gasterosteus aculeatus) is a powerful model system to explore vertebrate sex chromosome evolution, as it possesses an XY sex chromosome pair at relatively early stages of differentiation. Using a combination of whole-genome and transcriptome sequencing, we characterized sequence evolution and gene expression across the sex chromosomes. We uncovered two distinct evolutionary strata that correspond with known structural rearrangements on the Y chromosome. In the oldest stratum, only a handful of genes remain, and these genes are under strong purifying selection. By comparing sex-linked gene expression with expression of autosomal orthologs in an outgroup, we show that dosage compensation has not evolved in threespine sticklebacks through upregulation of the X chromosome in males. Instead, in the oldest stratum, the genes that still possess a Y chromosome allele are enriched for genes predicted to be dosage sensitive in mammals and yeast. Our results suggest that dosage imbalances may have been avoided at haploinsufficient genes by retaining function of the Y chromosome allele through strong purifying selection. PMID:25818858

YBR/EiJ mice: a new model of glaucoma caused by genes on chromosomes 4 and 17

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K. Saidas Nair

2016-08-01

Full Text Available A variety of inherited animal models with different genetic causes and distinct genetic backgrounds are needed to help dissect the complex genetic etiology of glaucoma. The scarcity of such animal models has hampered progress in glaucoma research. Here, we introduce a new inherited glaucoma model: the inbred mouse strain YBR/EiJ (YBR. YBR mice develop a form of pigmentary glaucoma. They exhibit a progressive age-related pigment-dispersing iris disease characterized by iris stromal atrophy. Subsequently, these mice develop elevated intraocular pressure (IOP and glaucoma. Genetic mapping studies utilizing YBR as a glaucoma-susceptible strain and C57BL/6J as a glaucoma-resistant strain were performed to identify genetic loci responsible for the iris disease and high IOP. A recessive locus linked to Tyrp1b on chromosome 4 contributes to iris stromal atrophy and high IOP. However, this is not the only important locus. A recessive locus on YBR chromosome 17 causes high IOP independent of the iris stromal atrophy. In specific eyes with high IOP caused by YBR chromosome 17, the drainage angle (through which ocular fluid leaves the eye is largely open. The YBR alleles of genes on chromosomes 4 and 17 underlie the development of high IOP and glaucoma but do so through independent mechanisms. Together, these two loci act in an additive manner to increase the susceptibility of YBR mice to the development of high IOP. The chromosome 17 locus is important not only because it causes IOP elevation in mice with largely open drainage angles but also because it exacerbates IOP elevation and glaucoma induced by pigment dispersion. Therefore, YBR mice are a valuable resource for studying the genetic etiology of IOP elevation and glaucoma, as well as for testing new treatments.

Cytogenetic analysis of quinoa chromosomes using nanoscale imaging and spectroscopy techniques

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Yangquanwei, Zhong; Neethirajan, Suresh; Karunakaran, Chithra

2013-11-01

Here we present a high-resolution chromosomal spectral map derived from synchrotron-based soft X-ray spectromicroscopy applied to quinoa species. The label-free characterization of quinoa metaphase chromosomes shows that it consists of organized substructures of DNA-protein complex. The analysis of spectra of chromosomes using the scanning transmission X-ray microscope (STXM) and its superposition of the pattern with the atomic force microscopy (AFM) and scanning electron microscopy (SEM) images proves that it is possible to precisely locate the gene loci and the DNA packaging inside the chromosomes. STXM has been successfully used to distinguish and quantify the DNA and protein components inside the quinoa chromosomes by visualizing the interphase at up to 30-nm spatial resolution. Our study represents the successful attempt of non-intrusive interrogation and integrating imaging techniques of chromosomes using synchrotron STXM and AFM techniques. The methodology developed for 3-D imaging of chromosomes with chemical specificity and temporal resolution will allow the nanoscale imaging tools to emerge from scientific research and development into broad practical applications such as gene loci tools and biomarker libraries.

Structurally Complex Organization of Repetitive DNAs in the Genome of Cobia (Rachycentron canadum).

Science.gov (United States)

Costa, Gideão W W F; Cioffi, Marcelo de B; Bertollo, Luiz A C; Molina, Wagner F

2015-06-01

Repetitive DNAs comprise the largest fraction of the eukaryotic genome. They include microsatellites or simple sequence repeats (SSRs), which play an important role in the chromosome differentiation among fishes. Rachycentron canadum is the only representative of the family Rachycentridae. This species has been focused on several multidisciplinary studies in view of its important potential for marine fish farming. In the present study, distinct classes of repetitive DNAs, with emphasis on SSRs, were mapped in the chromosomes of this species to improve the knowledge of its genome organization. Microsatellites exhibited a diversified distribution, both dispersed in euchromatin and clustered in the heterochromatin. The multilocus location of SSRs strengthened the heterochromatin heterogeneity in this species, as suggested by some previous studies. The colocalization of SSRs with retrotransposons and transposons pointed to a close evolutionary relationship between these repetitive sequences. A number of heterochromatic regions highlighted a greater complex organization than previously supposed, harboring a diversity of repetitive elements. In this sense, there was also evidence of colocalization of active genetic regions and different classes of repetitive DNAs in a common heterochromatic region, which offers a potential opportunity for further researches regarding the interaction of these distinct fractions in fish genomes.

Meiotic events in Oenothera - a non-standard pattern of chromosome behaviour.

Science.gov (United States)

Golczyk, Hieronim; Musiał, Krystyna; Rauwolf, Uwe; Meurer, Jörg; Herrmann, Reinhold G; Greiner, Stephan

2008-11-01

The genus Oenothera shows an intriguing extent of permanent translocation heterozygosity. Reciprocal translocations of chromosome arms in species or populations result in various kinds of chromosome multivalents in diakinesis. Early meiotic events conditioning such chromosome behaviour are poorly understood. We found a surprising uniformity of the leptotene-diplotene period, regardless of the chromosome configuration at diakinesis (ring of 14, 7 bivalents, mixture of bivalents and multivalents). It appears that the earliest chromosome interactions at Oenothera meiosis are untypical, since they involve pericentromeric regions. During early leptotene, proximal chromosome parts cluster and form a highly polarized Rabl configuration. Telomeres associated in pairs were seen at zygotene. The high degree of polarization of meiotic nuclei continues for an exceptionally long period, i.e., during zygotene-pachytene into the diplotene contraction stage. The Rabl-polarized meiotic architecture and clustering of pericentromeres suggest a high complexity of karyotypes, not only in structural heterozygotes but also in bivalent-forming homozygous species.

Genomic binding profiles of functionally distinct RNA polymerase III transcription complexes in human cells.

Science.gov (United States)

Moqtaderi, Zarmik; Wang, Jie; Raha, Debasish; White, Robert J; Snyder, Michael; Weng, Zhiping; Struhl, Kevin

2010-05-01

Genome-wide occupancy profiles of five components of the RNA polymerase III (Pol III) machinery in human cells identified the expected tRNA and noncoding RNA targets and revealed many additional Pol III-associated loci, mostly near short interspersed elements (SINEs). Several genes are targets of an alternative transcription factor IIIB (TFIIIB) containing Brf2 instead of Brf1 and have extremely low levels of TFIIIC. Strikingly, expressed Pol III genes, unlike nonexpressed Pol III genes, are situated in regions with a pattern of histone modifications associated with functional Pol II promoters. TFIIIC alone associates with numerous ETC loci, via the B box or a novel motif. ETCs are often near CTCF binding sites, suggesting a potential role in chromosome organization. Our results suggest that human Pol III complexes associate preferentially with regions near functional Pol II promoters and that TFIIIC-mediated recruitment of TFIIIB is regulated in a locus-specific manner.

Impact of various parameters in detecting chromosomal aberrations by FISH to describe radiosensitivity

International Nuclear Information System (INIS)

Keller, U.; Mueller, E.; Grabenbauer, G.; Sauer, R.; Distel, L.; Kuechler, A.; Liehr, T.

2004-01-01

Background and purpose: analysis of radiation-induced chromosomal aberrations is regarded as the ''gold standard'' for classifying individual radiosensitivity. A variety of different parameters can be used. The crucial question, however, is to explore which parameter is suited best to describe the differences between patients with increased radiosensitivity and healthy individuals. Patients and methods: in this study, five patients with severe radiation-induced late effects of at least grade 3, classified according to the Radiation Therapy Oncology Group (RTOG), and eleven healthy individuals were examined retrospectively. Peripheral blood lymphocytes were irradiated in vitro with 0.7 Gy and 2.0 Gy prior to cultivation and stained by means of three-color fluorescence in situ hybridization (FISH). The detailed analysis was focused on the number of breaks per metaphase, on breaks from complex chromosomal rearrangements per metaphase, as well as on the percentage of translocations, dicentric chromosomes, breaks, and excess acentric fragments - each in comparison with the total number of mitoses analyzed. Results: using the number of breaks from complex chromosomal rearrangements after 2.0 Gy, radiosensitive patients as endpoint were clearly to be distinguished (p = 0.001) from healthy individuals. Translocations (p = 0.001) as well as breaks per metaphase (p = 0.002) were also suitable indicators for detecting differences between patients and healthy individuals. The parameters ''percentage of dicentric chromosomes'', ''breaks'', and ''excess acentric fragments'' in comparison to the total number of mitoses analyzed could neither serve as meaningful nor as significant criteria, since they showed a strong interindividual variability. Conclusion: to detect a difference in chromosomal aberrations between healthy and radiosensitive individuals, the parameters ''frequency of breaks per metaphase'', ''complex chromosomal rearrangements'', and ''translocations'' are most

Identical functional organization of nonpolytene and polytene chromosomes in Drosophila melanogaster.

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Tatyana Yu Vatolina

Full Text Available Salivary gland polytene chromosomes demonstrate banding pattern, genetic meaning of which is an enigma for decades. Till now it is not known how to mark the band/interband borders on physical map of DNA and structures of polytene chromosomes are not characterized in molecular and genetic terms. It is not known either similar banding pattern exists in chromosomes of regular diploid mitotically dividing nonpolytene cells. Using the newly developed approach permitting to identify the interband material and localization data of interband-specific proteins from modENCODE and other genome-wide projects, we identify physical limits of bands and interbands in small cytological region 9F13-10B3 of the X chromosome in D. melanogaster, as well as characterize their general molecular features. Our results suggests that the polytene and interphase cell line chromosomes have practically the same patterns of bands and interbands reflecting, probably, the basic principle of interphase chromosome organization. Two types of bands have been described in chromosomes, early and late-replicating, which differ in many aspects of their protein and genetic content. As appeared, origin recognition complexes are located almost totally in the interbands of chromosomes.

Intercontinental spread of a genetically distinctive complex of clones of Neisseria meningitidis causing epidemic disease.

Science.gov (United States)

Caugant, D A; Frøholm, L O; Bøvre, K; Holten, E; Frasch, C E; Mocca, L F; Zollinger, W D; Selander, R K

1986-07-01

Strains of Neisseria meningitidis responsible for an epidemic of meningococcal disease occurring in Norway since the mid-1970s and for recent increases in the incidence of disease in several other parts of Europe have been identified by multilocus enzyme electrophoresis as members of a distinctive group of 22 closely related clones (the ET-5 complex). Clones of this complex have also colonized South Africa, Chile, Cuba, and Florida, where they have been identified as the causative agents of recent outbreaks of meningococcal disease. There is strong circumstantial evidence that outbreaks of disease occurring in Miami in 1981 and 1982 were caused in large part by bacteria that reached Florida via human immigrants from Cuba.

Dynamics of Escherichia coli Chromosome Segregation during Multifork Replication

DEFF Research Database (Denmark)

Nielsen, Henrik Jørck; Youngren, Brenda; Hansen, Flemming G.

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 chro......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...

Comparison of C. elegans and C. briggsae genome sequences reveals extensive conservation of chromosome organization and synteny.

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LaDeana W Hillier

2007-07-01

Full Text Available To determine whether the distinctive features of Caenorhabditis elegans chromosomal organization are shared with the C. briggsae genome, we constructed a single nucleotide polymorphism-based genetic map to order and orient the whole genome shotgun assembly along the six C. briggsae chromosomes. Although these species are of the same genus, their most recent common ancestor existed 80-110 million years ago, and thus they are more evolutionarily distant than, for example, human and mouse. We found that, like C. elegans chromosomes, C. briggsae chromosomes exhibit high levels of recombination on the arms along with higher repeat density, a higher fraction of intronic sequence, and a lower fraction of exonic sequence compared with chromosome centers. Despite extensive intrachromosomal rearrangements, 1:1 orthologs tend to remain in the same region of the chromosome, and colinear blocks of orthologs tend to be longer in chromosome centers compared with arms. More strikingly, the two species show an almost complete conservation of synteny, with 1:1 orthologs present on a single chromosome in one species also found on a single chromosome in the other. The conservation of both chromosomal organization and synteny between these two distantly related species suggests roles for chromosome organization in the fitness of an organism that are only poorly understood presently.

Managing today's complex healthcare business enterprise: reflections on distinctive requirements of healthcare management education.

Science.gov (United States)

Welton, William E

2004-01-01

In early 2001, the community of educational programs offering master's-level education in healthcare management began an odyssey to modernize its approach to the organization and delivery of healthcare management education. The community recognized that cumulative long-term changes within healthcare management practice required a careful examination of healthcare management context and manpower requirements. This article suggests an evidence-based rationale for defining the distinctive elements of healthcare management, thus suggesting a basis for review and transformation of master's-level healthcare management curricula. It also suggests ways to modernize these curricula in a manner that recognizes the distinctiveness of the healthcare business enterprise as well as the changing management roles and careers within these complex organizations and systems. Through such efforts, the healthcare management master's-level education community would be better prepared to meet current and future challenges, to increase its relevance to the management practice community, and to allocate scarce faculty and program resources more effectively.

Fishing for radiation quality: chromosome aberrations and the role of radiation track structure

International Nuclear Information System (INIS)

Hill, M.A.

2015-01-01

The yield of chromosome aberrations is not only dependent on dose but also on radiation quality, with high linear energy transfer (LET) typically having a greater biological effectiveness per unit dose than those of low-LET radiation. Differences in radiation track structure and cell morphology can also lead to quantitative differences in the spectra of the resulting chromosomal rearrangements, especially at low doses associated with typical human exposures. The development of combinatorial fluorescent labelling techniques (such as mFISH and mBAND) has helped to reveal the complexity of rearrangements, showing increasing complexity of observed rearrangements with increasing LET but has a resolution limited to ∼10 MBp. High-LET particles have not only been shown to produce clustered sites of DNA damage but also produce multiple correlated breaks along its path resulting in DNA fragments smaller than the resolution of these techniques. Additionally, studies have shown that the vast majority of radiation-induced HPRT mutations were also not detectable using fluorescent in situ hybridisation (FISH) techniques, with correlation of breaks along the track being reflected in the complexity of mutations, with intra- and inter-chromosomal insertions, and inversions occurring at the sites of some of the deletions. Therefore, the analysis of visible chromosomal rearrangements observed using current FISH techniques is likely to represent just the tip of the iceberg, considerably underestimating the extent and complexity of radiation induced rearrangements. (author)

Absence of Non-histone Protein Complexes at Natural Chromosomal Pause Sites Results in Reduced Replication Pausing in Aging Yeast Cells

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Marleny Cabral

2016-11-01

Full Text Available There is substantial evidence that genomic instability increases during aging. Replication pausing (and stalling at difficult-to-replicate chromosomal sites may induce genomic instability. Interestingly, in aging yeast cells, we observed reduced replication pausing at various natural replication pause sites (RPSs in ribosomal DNA (rDNA and non-rDNA locations (e.g., silent replication origins and tRNA genes. The reduced pausing occurs independent of the DNA helicase Rrm3p, which facilitates replication past these non-histone protein-complex-bound RPSs, and is independent of the deacetylase Sir2p. Conditions of caloric restriction (CR, which extend life span, also cause reduced replication pausing at the 5S rDNA and at tRNA genes. In aged and CR cells, the RPSs are less occupied by their specific non-histone protein complexes (e.g., the preinitiation complex TFIIIC, likely because members of these complexes have primarily cytosolic localization. These conditions may lead to reduced replication pausing and may lower replication stress at these sites during aging.

Mechanisms and consequences of paternally transmitted chromosomal abnormalities

Energy Technology Data Exchange (ETDEWEB)

Marchetti, F; Wyrobek, A J

2005-04-05

Paternally transmitted chromosomal damage has been associated with pregnancy loss, developmental and morphological defects, infant mortality, infertility, and genetic diseases in the offspring including cancer. There is epidemiological evidence linking paternal exposure to occupational or environmental agents with an increased risk of abnormal reproductive outcomes. There is also a large body of literature on germ cell mutagenesis in rodents showing that treatment of male germ cells with mutagens has dramatic consequences on reproduction producing effects such as those observed in human epidemiological studies. However, we know very little about the etiology, transmission and early embryonic consequences of paternally-derived chromosomal abnormalities. The available evidence suggests that: (1) there are distinct patterns of germ cell-stage differences in the sensitivity of induction of transmissible genetic damage with male postmeiotic cells being the most sensitive; (2) cytogenetic abnormalities at first metaphase after fertilization are critical intermediates between paternal exposure and abnormal reproductive outcomes; and, (3) there are maternally susceptibility factors that may have profound effects on the amount of sperm DNA damage that is converted into chromosomal aberrations in the zygote and directly affect the risk for abnormal reproductive outcomes.

Chromosomal aberration

International Nuclear Information System (INIS)

Ishii, Yutaka

1988-01-01

Chromosomal aberrations are classified into two types, chromosome-type and chromatid-type. Chromosom-type aberrations include terminal deletion, dicentric, ring and interstitial deletion, and chromatid-type aberrations include achromatic lesion, chromatid deletion, isochromatid deletion and chromatid exchange. Clastogens which induce chromosomal aberration are divided into ''S-dependent'' agents and ''S-independent''. It might mean whether they can induce double strand breaks independent of the S phase or not. Double strand breaks may be the ultimate lesions to induce chromosomal aberrations. Caffeine added even in the G 2 phase appeared to modify the frequency of chromatid aberrations induced by X-rays and mitomycin C. Those might suggest that the G 2 phase involves in the chromatid aberration formation. The double strand breaks might be repaired by ''G 2 repair system'', the error of which might yield breakage types of chromatid aberrations and the by-pass of which might yield chromatid exchanges. Chromosome-type aberrations might be formed in the G 1 phase. (author)

Chromosomal structures and repetitive sequences divergence in Cucumis species revealed by comparative cytogenetic mapping.

Science.gov (United States)

Zhang, Yunxia; Cheng, Chunyan; Li, Ji; Yang, Shuqiong; Wang, Yunzhu; Li, Ziang; Chen, Jinfeng; Lou, Qunfeng

2015-09-25

Differentiation and copy number of repetitive sequences affect directly chromosome structure which contributes to reproductive isolation and speciation. Comparative cytogenetic mapping has been verified an efficient tool to elucidate the differentiation and distribution of repetitive sequences in genome. In present study, the distinct chromosomal structures of five Cucumis species were revealed through genomic in situ hybridization (GISH) technique and comparative cytogenetic mapping of major satellite repeats. Chromosome structures of five Cucumis species were investigated using GISH and comparative mapping of specific satellites. Southern hybridization was employed to study the proliferation of satellites, whose structural characteristics were helpful for analyzing chromosome evolution. Preferential distribution of repetitive DNAs at the subtelomeric regions was found in C. sativus, C hystrix and C. metuliferus, while majority was positioned at the pericentromeric heterochromatin regions in C. melo and C. anguria. Further, comparative GISH (cGISH) through using genomic DNA of other species as probes revealed high homology of repeats between C. sativus and C. hystrix. Specific satellites including 45S rDNA, Type I/II, Type III, Type IV, CentM and telomeric repeat were then comparatively mapped in these species. Type I/II and Type IV produced bright signals at the subtelomeric regions of C. sativus and C. hystrix simultaneously, which might explain the significance of their amplification in the divergence of Cucumis subgenus from the ancient ancestor. Unique positioning of Type III and CentM only at the centromeric domains of C. sativus and C. melo, respectively, combining with unique southern bands, revealed rapid evolutionary patterns of centromeric DNA in Cucumis. Obvious interstitial telomeric repeats were observed in chromosomes 1 and 2 of C. sativus, which might provide evidence of the fusion hypothesis of chromosome evolution from x = 12 to x = 7 in

G-banding analysis of radiation-induced chromosome damage in lymphocytes of Hiroshima atomic-bomb survivors

International Nuclear Information System (INIS)

Ohtaki, Kazuo; Nakashima, Eiji.

1994-06-01

This report describes the G-banding analysis of somatic chromosomes in lymphocytes from 63 atomic-bomb survivors in Hiroshima to determine the type and frequency of radiation-induced chromosome aberrations. Summary findings are as follows: (1) The cells with stable-type chromosome aberrations (Cs cells) predominated among the aberrant cells and showed a dose-dependent increase. All stable chromosome aberrations were classified into 9 types: reciprocal translocations (t), translocations of complex type (t-cx), insertions (ins), complex exchanges (e-cx), peri- and paracentric inversions (inv-peri, inv-para), terminal and interstitial deletions (del-ter, del-int), and unidentified rearrangements. Aberration frequencies increased with increasing dose for all aberration categories. Among the chromosome aberrations classified, reciprocal translocations predominated in all dose ranges. The frequencies of complex aberrations were low at the low-dose level but increased sharply as dose increased. (2) The linear model was fitted to test the dose-response relationship for Cs-cell frequencies. With a constant neutron relative biological effectiveness of 10, an estimated linear slope of 15.2%/Sv was obtained for Dosimetry System 1986 bone-marrow dose with an intercept of 2.9% at dose 0. The present observation confirmed a wide variability of Cs-cell frequencies among individual survivors in every dose category.(3) Statistical analysis of data on 3370 break sites showed good correlations between relative DNA content and the distribution of chromosome breaks involved in translocations, although the involvement of chromosome 1 is significantly higher, for as-yet-unknown reasons. (J.P.N.)

Y-chromosome evolution: emerging insights into processes of Y-chromosome degeneration.

Science.gov (United States)

Bachtrog, Doris

2013-02-01

The human Y chromosome is intriguing not only because it harbours the master-switch gene that determines gender but also because of its unusual evolutionary history. The Y chromosome evolved from an autosome, and its evolution has been characterized by massive gene decay. Recent whole-genome and transcriptome analyses of Y chromosomes in humans and other primates, in Drosophila species and in plants have shed light on the current gene content of the Y chromosome, its origins and its long-term fate. Furthermore, comparative analysis of young and old Y chromosomes has given further insights into the evolutionary and molecular forces triggering Y-chromosome degeneration and into the evolutionary destiny of the Y chromosome.

Chromosomal abnormalities in human glioblastomas: gain in chromosome 7p correlating with loss in chromosome 10q.

Science.gov (United States)

Inda, María del Mar; Fan, Xing; Muñoz, Jorge; Perot, Christine; Fauvet, Didier; Danglot, Giselle; Palacio, Ana; Madero, Pilar; Zazpe, Idoya; Portillo, Eduardo; Tuñón, Teresa; Martínez-Peñuela, José María; Alfaro, Jorge; Eiras, José; Bernheim, Alain; Castresana, Javier S

2003-01-01

Various genomic alterations have been detected in glioblastoma. Chromosome 7p, with the epidermal growth factor receptor locus, together with chromosome 10q, with the phosphatase and tensin homologue deleted in chromosome 10 and deleted in malignant brain tumors-1 loci, and chromosome 9p, with the cyclin-dependent kinase inhibitor 2A locus, are among the most frequently damaged chromosomal regions in glioblastoma. In this study, we evaluated the genetic status of 32 glioblastomas by comparative genomic hybridization; the sensitivity of comparative genomic hybridization versus differential polymerase chain reaction to detect deletions at the phosphatase and tensin homologue deleted in chromosome 10, deleted in malignant brain tumors-1, and cyclin-dependent kinase inhibitor 2A loci and amplifications at the cyclin-dependent kinase 4 locus; the frequency of genetic lesions (gain or loss) at 16 different selected loci (including oncogenes, tumor-suppressor genes, and proliferation markers) mapping on 13 different chromosomes; and the possible existence of a statistical association between any pair of molecular markers studied, to subdivide the glioblastoma entity molecularly. Comparative genomic hybridization showed that the most frequent region of gain was chromosome 7p, whereas the most frequent losses occurred on chromosomes 10q and 13q. The only statistically significant association was found for 7p gain and 10q loss. Copyright 2002 Wiley-Liss, Inc.

A Simple Key for Identifying the Sibling Species of the Malaria Vector Anopheles gambiae (Giles Complex by Polytene Chromosome Cytogenetics

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Music Temitope OBEMBE

2018-03-01

Full Text Available It has been established that Anopheles gambiae complex sibling species are the major Plasmodium malaria vectors in Africa; however, not all the sibling species transmit the infection. Easier molecular methods, PCR-based assays, have been developed to distinguish the several members of the A. gambiae complex. However, malaria vector research in less developed countries, particularly sub-Saharan Africa, is being hampered by the lack of PCR facilities in laboratories and the cost of carrying out the assay within lack of funding. Hence, the present study was designed to develop a simple identification key, based on an affordable method of polytene chromosome cytotaxonomy, for identifying the major P. falciparum vectors. The Identification Key was successfully used to identify two members of the A. gambiae complex, A. gambiae sensu stricto and A. arabiensis, which are the most potent malaria vectors in Africa; even so, it could not be used to establish the infective and the refractory strains.

The effect of track structure on the induction of chromosomal aberrations in murine cells

Science.gov (United States)

Durante, M.; Cella, L.; Furusawa, Y.; George, K.; Gialanella, G.; Grossi, G.; Pugliese, M.; Saito, M.; Yang, T. C.

1998-01-01

PURPOSE: To measure chromosome aberrations in C3H 10T1/2 mouse fibroblasts using FISH painting at the first mitosis following exposure to 30 keV/microm hydrogen or neon ions. MATERIALS AND METHODS: Cells in plateau-phase were irradiated with 0.86 MeV protons at the TTT-3 Tandem accelerator in Naples (Italy), or with 400 MeV/n Ne ions at the HIMAC accelerator in Chiba (Japan). Colcemid-blocked cells were harvested at the first mitosis following exposure, and chromosome spreads were hybridized in situ with a fluorescein-labelled composite mouse DNA probe specific for chromosomes 2 and 8. RESULTS: Protons were more efficient than neon ions at the same LET in the induction of chromosome interchanges and breaks. Yields of complex exchanges were similar for both particles at the same dose, but protons produced mostly insertions, while with Ne exposure non-reciprocal exchanges were the most frequent complex-type exchange. CONCLUSIONS: Charged particles with the same LET produce different yields of chromosome aberrations, and some observed differences can be explained based on the available track-structure models.

Chromosome aberrations of bone marrow cells in heavily exposed atomic bomb survivors

International Nuclear Information System (INIS)

Tanaka, Kimio; Kamada, Nanao; Kuramoto, Atsushi; Ohkita, Takeshi

1986-01-01

Seven hundred and ten bone marrow cells from 13 A-bomb survivors, who were heavily exposed to atomic radiation, were examined using chromosome banding method. An average frequency of chromosome aberrations was 17 %. The most common structural abnormality was translocation (47 %), followed by complex aberrations involving three or more chromosomes (32 %). These abnormalities were frequently seen in A-bomb survivors exposed to estimated doses of 3.5 - 4.0 Gy. Eighty two percent of the structural aberrations were stable. Diploid cells were seen in 0.4 % and tetraploid cells were seen in 0.7 %. The frequency of breakpoint sites was high in chromosomes 1 and 17; while it was low in chromosomes 3, 6, 9, and 11. Abnormal clones were seen in one of the 13 survivors. Chromosome aberrations common to the bone marrow cells and peripheral lymphocytes were not seen in the same individual. (Namekawa, K.)

ParABS system in chromosome partitioning in the bacterium Myxococcus xanthus.

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Antonio A Iniesta

Full Text Available Chromosome segregation is an essential cellular function in eukaryotic and prokaryotic cells. The ParABS system is a fundamental player for a mitosis-like process in chromosome partitioning in many bacterial species. This work shows that the social bacterium Myxococcus xanthus also uses the ParABS system for chromosome segregation. Its large prokaryotic genome of 9.1 Mb contains 22 parS sequences near the origin of replication, and it is shown here that M. xanthus ParB binds preferentially to a consensus parS sequence in vitro. ParB and ParA are essential for cell viability in M. xanthus as in Caulobacter crescentus, but unlike in many other bacteria. Absence of ParB results in anucleate cells, chromosome segregation defects and loss of viability. Analysis of ParA subcellular localization shows that it clusters at the poles in all cells, and in some, in the DNA-free cell division plane between two chromosomal DNA masses. This ParA localization pattern depends on ParB but not on FtsZ. ParB inhibits the nonspecific interaction of ParA with DNA, and ParA colocalizes with chromosomal DNA only when ParB is depleted. The subcellular localization of ParB suggests a single ParB-parS complex localized at the edge of the nucleoid, next to a polar ParA cluster, with a second ParB-parS complex migrating after the replication of parS takes place to the opposite nucleoid edge, next to the other polar ParA cluster.

Enterobacter cloacae Complex Isolates Harboring blaNMC-A or blaIMI-Type Class A Carbapenemase Genes on Novel Chromosomal Integrative Elements and Plasmids.

Science.gov (United States)

Boyd, David A; Mataseje, Laura F; Davidson, Ross; Delport, Johannes A; Fuller, Jeff; Hoang, Linda; Lefebvre, Brigitte; Levett, Paul N; Roscoe, Diane L; Willey, Barbara M; Mulvey, Michael R

2017-05-01

Carbapenem-resistant Enterobacter cloacae complex isolates submitted to a reference laboratory from 2010 to 2015 were screened by PCR for seven common carbapenemase gene groups, namely, KPC, NDM, OXA-48, VIM, IMP, GES, and NMC-A/IMI. Nineteen of the submitted isolates (1.7%) were found to harbor Ambler class A bla NMC-A or bla IMI -type carbapenemases. All 19 isolates were resistant to at least one carbapenem but susceptible to aminoglycosides, trimethoprim-sulfamethoxazole, tigecycline, and ciprofloxacin. Most isolates (17/19) gave positive results with the Carba-NP test for phenotypic carbapenemase detection. Isolates were genetically diverse by pulsed-field gel electrophoresis macrorestriction analysis, multilocus sequence typing, and hsp60 gene analysis. The genes were found in various Enterobacter cloacae complex species; however, bla NMC-A was highly associated with Enterobacter ludwigii Whole-genome sequencing and bioinformatics analysis revealed that all NMC-A ( n = 10), IMI-1 ( n = 5), and IMI-9 ( n = 2) producers harbored the carbapenemase gene on EludIMEX-1-like integrative mobile elements (EcloIMEXs) located in the identical chromosomal locus. Two novel genes, bla IMI-5 and bla IMI-6 , were harbored on different IncFII-type plasmids. Enterobacter cloacae complex isolates harboring bla NMC-A/IMI -type carbapenemases are relatively rare in Canada. Though mostly found integrated into the chromosome, some variants are located on plasmids that may enhance their mobility potential. © Crown copyright 2017.

Slit scan flow cytometry of isolated chromosomes following fluorescence hybridization: an approach of online screening for specific chromosomes and chromosome translocations

NARCIS (Netherlands)

Hausmann, M.; Dudin, G.; Aten, J. A.; Heilig, R.; Diaz, E.; Cremer, C.

1991-01-01

The recently developed methods of non radioactive in situ hybridization of chromosomes offer new aspects for chromosome analysis. Fluorescent labelling of hybridized chromosomes or chromosomal subregions allows to facilitate considerably the detection of specific chromosomal abnormalities. For many

DistAMo: A web-based tool to characterize DNA-motif distribution on bacterial chromosomes

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Patrick eSobetzko

2016-03-01

Full Text Available Short DNA motifs are involved in a multitude of functions such as for example chromosome segregation, DNA replication or mismatch repair. Distribution of such motifs is often not random and the specific chromosomal pattern relates to the respective motif function. Computational approaches which quantitatively assess such chromosomal motif patterns are necessary. Here we present a new computer tool DistAMo (Distribution Analysis of DNA Motifs. The algorithm uses codon redundancy to calculate the relative abundance of short DNA motifs from single genes to entire chromosomes. Comparative genomics analyses of the GATC-motif distribution in γ-proteobacterial genomes using DistAMo revealed that (i genes beside the replication origin are enriched in GATCs, (ii genome-wide GATC distribution follows a distinct pattern and (iii genes involved in DNA replication and repair are enriched in GATCs. These features are specific for bacterial chromosomes encoding a Dam methyltransferase. The new software is available as a stand-alone or as an easy-to-use web-based server version at http://www.computational.bio.uni-giessen.de/distamo.

Copy number neutral loss of heterozygosity at 17p and homozygous mutations of TP53 are associated with complex chromosomal aberrations in patients newly diagnosed with myelodysplastic syndromes.

Science.gov (United States)

Svobodova, Karla; Zemanova, Zuzana; Lhotska, Halka; Novakova, Milena; Podskalska, Lucie; Belickova, Monika; Brezinova, Jana; Sarova, Iveta; Izakova, Silvia; Lizcova, Libuse; Berkova, Adela; Siskova, Magda; Jonasova, Anna; Cermak, Jaroslav; Michalova, Kyra

2016-03-01

Complex karyotypes are seen in approximately 20% of patients with myelodysplastic syndromes (MDS) and are associated with a high risk of transformation to acute myeloid leukemia and poor outcomes in patients. Copy number neutral loss of heterozygosity (CN-LOH, i.e., both copies of a chromosomal pair or their parts originate from one parent) might contribute to increased genomic instability in the bone-marrow cells of patients with MDS. The pathological potential of CN-LOH, which arises as a clonal aberration in a proportion of somatic cells, consists of tumor suppressor gene and oncogene homozygous mutations. The aim of our study was to evaluate the frequency of CN-LOH at 17p in bone-marrow cells of newly diagnosed MDS patients with complex chromosomal aberrations and to assess its correlation with mutations in the TP53 gene (17p13.1). CN-LOH was detected in 40 chromosomal regions in 21 (29%) of 72 patients analyzed. The changes in 27 of the 40 regions identified were sporadic. The most common finding was CN-LOH of the short arm of chromosome 17, which was detected in 13 (18%) of 72 patients. A mutational analysis confirmed the homozygous mutation of TP53 in all CN-LOH 17p patients, among which two frameshift mutations are not registered in the International Agency for Research on Cancer TP53 Database. CN-LOH 17p correlated with aggressive disease (median overall survival 4 months) and was strongly associated with a complex karyotype in the cohort studied, which might cause rapid disease progression in high-risk MDS. No other CN-LOH region previously recorded in MDS or AML patients (1p, 4q, 7q, 11q, 13q, 19q, 21q) was detected in our cohort of patients with complex karyotype examined at the diagnosis of MDS. The LOH region appeared to be balanced (i.e., with no DNA copy number change) when examined with conventional and molecular cytogenetic methods. Therefore, a microarray that detects single-nucleotide polymorphisms is an ideal method with which to identify and

A genome-wide map of aberrantly expressed chromosomal islands in colorectal cancer

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Castanos-Velez Esmeralda

2006-09-01

Full Text Available Abstract Background Cancer development is accompanied by genetic phenomena like deletion and amplification of chromosome parts or alterations of chromatin structure. It is expected that these mechanisms have a strong effect on regional gene expression. Results We investigated genome-wide gene expression in colorectal carcinoma (CRC and normal epithelial tissues from 25 patients using oligonucleotide arrays. This allowed us to identify 81 distinct chromosomal islands with aberrant gene expression. Of these, 38 islands show a gain in expression and 43 a loss of expression. In total, 7.892 genes (25.3% of all human genes are located in aberrantly expressed islands. Many chromosomal regions that are linked to hereditary colorectal cancer show deregulated expression. Also, many known tumor genes localize to chromosomal islands of misregulated expression in CRC. Conclusion An extensive comparison with published CGH data suggests that chromosomal regions known for frequent deletions in colon cancer tend to show reduced expression. In contrast, regions that are often amplified in colorectal tumors exhibit heterogeneous expression patterns: even show a decrease of mRNA expression. Because for several islands of deregulated expression chromosomal aberrations have never been observed, we speculate that additional mechanisms (like abnormal states of regional chromatin also have a substantial impact on the formation of co-expression islands in colorectal carcinoma.

Cytogenetic and molecular analysis of inv dup(15) chromosomes observed in two patients with autistic disorder and mental retardation

Energy Technology Data Exchange (ETDEWEB)

Flejter, W.L. [Univ. of Utah, Salt Lake City, UT (United States); Bennett-Baker, P.E.; Gorski, J.L. [Univ. of Michigan, Ann Arbor, MI (United States)] [and other

1996-01-11

A variety of distinct phenotypes has been associated with supernumerary inv dup(15) chromosomes. Although different cytogenetic rearrangements have been associated with distinguishable clinical syndromes, precise genotype-phenotype correlations have not been determined. However, the availability of chromosome 15 DNA markers provides a means to characterize inv dup(15) chromosomes in detail to facilitate the determination of specific genotype-phenotype associations. We describe 2 patients with an autistic disorder, mental retardation, developmental delay, seizures, and supernumerary inv dup(15) chromosomes. Conventional and molecular cytogenetic studies confirmed the chromosomal origin of the supernumerary chromosomes and showed that the duplicated region extended to at least band 15q13. An analysis of chromosome 15 microsatellite CA polymorphisms suggested a maternal origin of the inv dup(15) chromosomes and biparental inheritance of the two intact chromosome 15 homologs. The results of this study add to the existing literature which suggests that the clinical phenotype of patients with a supernumerary inv dup(15) chromosome is determined not only by the extent of the duplicated region, but by the dosage of genes located within band 15q13 and the origin of the normal chromosomes 15. 21 refs., 2 figs., 1 tab.

Increased high-density lipoprotein cholesterol levels in mice with XX versus XY sex chromosomes.

Science.gov (United States)

Link, Jenny C; Chen, Xuqi; Prien, Christopher; Borja, Mark S; Hammerson, Bradley; Oda, Michael N; Arnold, Arthur P; Reue, Karen

2015-08-01

The molecular mechanisms underlying sex differences in dyslipidemia are poorly understood. We aimed to distinguish genetic and hormonal regulators of sex differences in plasma lipid levels. We assessed the role of gonadal hormones and sex chromosome complement on lipid levels using the four core genotypes mouse model (XX females, XX males, XY females, and XY males). In gonadally intact mice fed a chow diet, lipid levels were influenced by both male-female gonadal sex and XX-XY chromosome complement. Gonadectomy of adult mice revealed that the male-female differences are dependent on acute effects of gonadal hormones. In both intact and gonadectomized animals, XX mice had higher HDL cholesterol (HDL-C) levels than XY mice, regardless of male-female sex. Feeding a cholesterol-enriched diet produced distinct patterns of sex differences in lipid levels compared with a chow diet, revealing the interaction of gonadal and chromosomal sex with diet. Notably, under all dietary and gonadal conditions, HDL-C levels were higher in mice with 2 X chromosomes compared with mice with an X and Y chromosome. By generating mice with XX, XY, and XXY chromosome complements, we determined that the presence of 2 X chromosomes, and not the absence of the Y chromosome, influences HDL-C concentration. We demonstrate that having 2 X chromosomes versus an X and Y chromosome complement drives sex differences in HDL-C. It is conceivable that increased expression of genes escaping X-inactivation in XX mice regulates downstream processes to establish sexual dimorphism in plasma lipid levels. © 2015 American Heart Association, Inc.

A distinct alleles and genetic recombination of pmrCAB operon in species of Acinetobacter baumannii complex isolates.

Science.gov (United States)

Kim, Dae Hun; Ko, Kwan Soo

2015-07-01

To investigate pmrCAB sequence divergence in 5 species of Acinetobacter baumannii complex, a total of 80 isolates from a Korean hospital were explored. We evaluated nucleotide and amino acid polymorphisms of pmrCAB operon, and phylogenetic trees were constructed for each gene of prmCAB operon. Colistin and polymyxin B susceptibility was determined for all isolates, and multilocus sequence typing was also performed for A. baumannii isolates. Our results showed that each species of A. baumannii complex has divergent pmrCAB operon sequences. We identified a distinct pmrCAB allele allied with Acinetobacter nosocomialis in gene trees. Different grouping in each gene tree suggests sporadic recombination or emergence of pmrCAB genes among Acinetobacter species. Sequence polymorphisms among Acinetobacter species might not be associated with colistin resistance. We revealed that a distinct pmrCAB allele may be widespread across the continents such as North America and Asia and that sporadic genetic recombination or emergence of pmrCAB genes might occur. Copyright © 2015 Elsevier Inc. All rights reserved.

The two chromosomes of Vibrio cholerae are initiated at different time points in the cell cycle

DEFF Research Database (Denmark)

Rasmussen, Tue; Jensen, Rasmus Bugge; Skovgaard, Ole

2007-01-01

for analysing flow cytometry data and marker frequency analysis, we show that the small chromosome II is replicated late in the C period of the cell cycle, where most of chromosome I has been replicated. Owing to the delay in initiation of chromosome II, the two chromosomes terminate replication...... at approximately the same time and the average number of replication origins per cell is higher for chromosome I than for chromosome II. Analysis of cell-cycle parameters shows that chromosome replication and segregation is exceptionally fast in V. cholerae. The divided genome and delayed replication of chromosome...... II may reduce the metabolic burden and complexity of chromosome replication by postponing DNA synthesis to the last part of the cell cycle and reducing the need for overlapping replication cycles during rapid proliferation...

Effect of 2,4-D and isoproturon on chromosomal disturbances during mitotic division in root tip cells of Triticum aestivum L.

Science.gov (United States)

Kumar, Sanjay

2010-01-01

The widespread use of the herbicides for weed control and crop productivity in modern agriculture exert a threat on economically important crops by way of cytological damage to the cells of the crop plant or side effects, if any, induced by the herbicides. In the present communication, author describes the effects of 2,4-D and Isoproturon on chromosomal morphology in mitotic cells of Triticum aestivum L. The wheat seedlings were treated with range of concentrations (50-1200 ppm) of 2,4-D and Isoproturon for 72 h at room temperature. In the mitotic cells, twelve distinct chromosome structure abnormalities were observed over control. The observed irregularities were stickiness, c-mitosis, multipolar chromosomes with or without spindles, fragments and bridges, lagging chromosomes, unequal distribution of chromosomes, over contracted chromosomes, unoriented chromosomes, star shaped arrangement of the chromosomes, increased cell size and failure of cell plate formation. The abnormalities like stickiness, fragments, bridges, lagging or dysjunction, unequal distribution and over contracted chromosomes meet frequently.

SV40 large T-p53 complex: evidence for the presence of two immunologically distinct forms of p53

International Nuclear Information System (INIS)

Milner, J.; Gamble, J.

1985-01-01

The transforming protein of SV40 is the large T antigen. Large T binds a cellular protein, p53, which is potentially oncogenic by virtue of its functional involvement in the control of cell proliferation. This raises the possibility that p53 may mediate, in part, the transforming function of SV40 large T. Two immunologically distinct forms of p53 have been identified in normal cells: the forms are cell-cycle dependent, one being restricted to nondividing cells (p53-Go) and the second to dividing cells (p53-G divided by). The authors have now dissociated and probed the multimeric complex of SV40 large T-p53 for the presence of immunologically distinct forms of p53. Here they present evidence for the presence of p53-Go and p53-G divided by complexed with SV40 large T

Mapping of the bovine spinal muscular atrophy locus to Chromosome 24.

Science.gov (United States)

Medugorac, Ivica; Kemter, Juliane; Russ, Ingolf; Pietrowski, Detlef; Nüske, Stefan; Reichenbach, Horst-Dieter; Schmahl, Wolfgang; Förster, Martin

2003-06-01

A hereditary form of spinal muscular atrophy (SMA) caused by an autosomal recessive gene has been reported for American Brown-Swiss cattle and in advanced backcrosses between American Brown-Swiss and many European brown cattle breeds. Bovine SMA (bovSMA) bears remarkable resemblance to the human SMA (SMA1). Affected homozygous calves also show progressive symmetric weakness and neurogenic atrophy of proximal muscles. The condition is characterized by severe muscle atrophy, quadriparesis, and sternal recumbency as result of neurogenic atrophy. We report on the localization of the gene causing bovSMA within a genomic interval between the microsatellite marker URB031 and the telomeric end of bovine Chromosome (Chr) 24 (BTA24). Linkage analysis of a complex pedigree of German Braunvieh cattle revealed a recombination fraction of 0.06 and a three-point lod score of 11.82. The results of linkage and haplotyping analysis enable a marker-assisted selection against bovSMA based on four microsatellite markers most telomeric on BTA24 to a moderate accuracy of 89-94%. So far, this region is not orthologous to any human chromosome segments responsible for twelve distinct disease phenotypes of autosomal neuropathies. Our results indicate the apoptosis-inhibiting protein BCL2 as the most promising positional candidate gene causing bovSMA. Our findings offer an attractive animal model for a better understanding of human forms of SMA and for a probable anti-apoptotic synergy of SMN-BCL2 aggregates in mammals.

Clonal evolution through loss of chromosomes and subsequent polyploidization in chondrosarcoma.

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Linda Olsson

Full Text Available Near-haploid chromosome numbers have been found in less than 1% of cytogenetically reported tumors, but seem to be more common in certain neoplasms including the malignant cartilage-producing tumor chondrosarcoma. By a literature survey of published karyotypes from chondrosarcomas we could confirm that loss of chromosomes resulting in hyperhaploid-hypodiploid cells is common and that these cells may polyploidize. Sixteen chondrosarcomas were investigated by single nucleotide polymorphism (SNP array and the majority displayed SNP patterns indicative of a hyperhaploid-hypodiploid origin, with or without subsequent polyploidization. Except for chromosomes 5, 7, 19, 20 and 21, autosomal loss of heterozygosity was commonly found, resulting from chromosome loss and subsequent duplication of monosomic chromosomes giving rise to uniparental disomy. Additional gains, losses and rearrangements of genetic material, and even repeated rounds of polyploidization, may affect chondrosarcoma cells resulting in highly complex karyotypes. Loss of chromosomes and subsequent polyploidization was not restricted to a particular chondrosarcoma subtype and, although commonly found in chondrosarcoma, binucleated cells did not seem to be involved in these events.

Clonal evolution through loss of chromosomes and subsequent polyploidization in chondrosarcoma.

Science.gov (United States)

Olsson, Linda; Paulsson, Kajsa; Bovée, Judith V M G; Nord, Karolin H

2011-01-01

Near-haploid chromosome numbers have been found in less than 1% of cytogenetically reported tumors, but seem to be more common in certain neoplasms including the malignant cartilage-producing tumor chondrosarcoma. By a literature survey of published karyotypes from chondrosarcomas we could confirm that loss of chromosomes resulting in hyperhaploid-hypodiploid cells is common and that these cells may polyploidize. Sixteen chondrosarcomas were investigated by single nucleotide polymorphism (SNP) array and the majority displayed SNP patterns indicative of a hyperhaploid-hypodiploid origin, with or without subsequent polyploidization. Except for chromosomes 5, 7, 19, 20 and 21, autosomal loss of heterozygosity was commonly found, resulting from chromosome loss and subsequent duplication of monosomic chromosomes giving rise to uniparental disomy. Additional gains, losses and rearrangements of genetic material, and even repeated rounds of polyploidization, may affect chondrosarcoma cells resulting in highly complex karyotypes. Loss of chromosomes and subsequent polyploidization was not restricted to a particular chondrosarcoma subtype and, although commonly found in chondrosarcoma, binucleated cells did not seem to be involved in these events.

Imaging of Chromosome Dynamics in Mouse Testis Tissue by Immuno-FISH.

Science.gov (United States)

Scherthan, Harry

2017-01-01

The mouse (Mus musculus) represents the central mammalian genetic model system for biomedical and developmental research. Mutant mouse models have provided important insights into chromosome dynamics during the complex meiotic differentiation program that compensates for the genome doubling at fertilization. Homologous chromosomes (homologues) undergo dynamic pairing and recombine during first meiotic prophase before they become partitioned into four haploid sets by two consecutive meiotic divisions that lack an intervening S-phase. Fluorescence in situ hybridization (FISH) has been instrumental in the visualization and imaging of the dynamic reshaping of chromosome territories and mobility during prophase I, in which meiotic telomeres were found to act as pacemakers for the chromosome pairing dance. FISH combined with immunofluorescence (IF) co-staining of nuclear proteins has been instrumental for the visualization and imaging of mammalian meiotic chromosome behavior. This chapter describes FISH and IF methods for the analysis of chromosome dynamics in nuclei of paraffin-embedded mouse testes. The techniques have proven useful for fresh and archived paraffin testis material of several mammalian species.

Novel method to load multiple genes onto a mammalian artificial chromosome.

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Anna Tóth

Full Text Available Mammalian artificial chromosomes are natural chromosome-based vectors that may carry a vast amount of genetic material in terms of both size and number. They are reasonably stable and segregate well in both mitosis and meiosis. A platform artificial chromosome expression system (ACEs was earlier described with multiple loading sites for a modified lambda-integrase enzyme. It has been shown that this ACEs is suitable for high-level industrial protein production and the treatment of a mouse model for a devastating human disorder, Krabbe's disease. ACEs-treated mutant mice carrying a therapeutic gene lived more than four times longer than untreated counterparts. This novel gene therapy method is called combined mammalian artificial chromosome-stem cell therapy. At present, this method suffers from the limitation that a new selection marker gene should be present for each therapeutic gene loaded onto the ACEs. Complex diseases require the cooperative action of several genes for treatment, but only a limited number of selection marker genes are available and there is also a risk of serious side-effects caused by the unwanted expression of these marker genes in mammalian cells, organs and organisms. We describe here a novel method to load multiple genes onto the ACEs by using only two selectable marker genes. These markers may be removed from the ACEs before therapeutic application. This novel technology could revolutionize gene therapeutic applications targeting the treatment of complex disorders and cancers. It could also speed up cell therapy by allowing researchers to engineer a chromosome with a predetermined set of genetic factors to differentiate adult stem cells, embryonic stem cells and induced pluripotent stem (iPS cells into cell types of therapeutic value. It is also a suitable tool for the investigation of complex biochemical pathways in basic science by producing an ACEs with several genes from a signal transduction pathway of interest.

Novel method to load multiple genes onto a mammalian artificial chromosome.

Science.gov (United States)

Tóth, Anna; Fodor, Katalin; Praznovszky, Tünde; Tubak, Vilmos; Udvardy, Andor; Hadlaczky, Gyula; Katona, Robert L

2014-01-01

Mammalian artificial chromosomes are natural chromosome-based vectors that may carry a vast amount of genetic material in terms of both size and number. They are reasonably stable and segregate well in both mitosis and meiosis. A platform artificial chromosome expression system (ACEs) was earlier described with multiple loading sites for a modified lambda-integrase enzyme. It has been shown that this ACEs is suitable for high-level industrial protein production and the treatment of a mouse model for a devastating human disorder, Krabbe's disease. ACEs-treated mutant mice carrying a therapeutic gene lived more than four times longer than untreated counterparts. This novel gene therapy method is called combined mammalian artificial chromosome-stem cell therapy. At present, this method suffers from the limitation that a new selection marker gene should be present for each therapeutic gene loaded onto the ACEs. Complex diseases require the cooperative action of several genes for treatment, but only a limited number of selection marker genes are available and there is also a risk of serious side-effects caused by the unwanted expression of these marker genes in mammalian cells, organs and organisms. We describe here a novel method to load multiple genes onto the ACEs by using only two selectable marker genes. These markers may be removed from the ACEs before therapeutic application. This novel technology could revolutionize gene therapeutic applications targeting the treatment of complex disorders and cancers. It could also speed up cell therapy by allowing researchers to engineer a chromosome with a predetermined set of genetic factors to differentiate adult stem cells, embryonic stem cells and induced pluripotent stem (iPS) cells into cell types of therapeutic value. It is also a suitable tool for the investigation of complex biochemical pathways in basic science by producing an ACEs with several genes from a signal transduction pathway of interest.

Development of a biological dosimeter for translocation scoring based on two-color fluorescence in situ hybridization of chromosome subsets

Energy Technology Data Exchange (ETDEWEB)

Popp, S; Cremer, T [Heidelberg Univ. (Germany). Inst. of Human Genetics and Anthropology

1992-03-01

Recently fluorescence in situ hybridization protocols have been developed which allow the paining of individual chromosomes using DNA-libraries from sorted human chromosomes. This approach has the particular advantage that radiation induced chromosome translocations can be easily detected, if chromosomes of distinctly different colors take part in the translocation event. To enhance the sensitivity of this approach two metaphase chromosome subsets A and B (A: chromosome 1, 2, 4, 8, 16; B: 3, 5, 9, 10, 13) were simultaneously painted in green and red color. Counterstaining of the chromosomes with DAPI resulted in a third subset which exhibited blue fluorescence only. Green-red, green-blue and red-blue translocation chromosomes could be easily detected after irradiation of lymphocyte cultures with {sup 137}Cs-{gamma}-rays. Analyses of painted chromosomes can be combined with conventional GTG-banding analyses. This new biological dosimeter should become useful to monitor both long term effects of single irradiation events and the cumulative effects of multiple or chronic irradiation exposure. In contrast to translocation scoring based on the analysis of banded chromosomes, this new approach has the particular advantage that a rapid, automated scoring of translocations can now be envisaged. (author).

Comparative Chromosome Painting and NOR Distribution Suggest a Complex Hybrid Origin of Triploid Lepidodactylus lugubris (Gekkonidae.

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Vladimir A Trifonov

Full Text Available Parthenogenesis, unisexuality and triploidy are interesting but poorly studied phenomena occurring in some reptile species. The mourning gecko (Lepidodactylus lugubris represents a complex of diploid and triploid parthenogenetic mostly all-female populations (males occur quite rarely widely distributed in coastal areas of the Indian and Pacific Oceans. Here, we study karyotypes of a male and two female L. lugubris (LLU triploid individuals (3n = 66 using comparative painting with Gekko japonicus, Hemidactylus turcicus and H. platyurus chromosome specific probes to visualize the homologous regions and to reveal genus specific rearrangements. Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs. Our results suggest that the karyotype of L. lugubris underwent a chromosome fission and a fusion after its divergence from a common ancestor of the Gekko-Hemidactylus group. The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals. It seems that three different bisexual populations might have contributed to the origin of this triploid parthenogenetic population. We postulate that the heterozygosity in NOR localization is maintained in the triploid clone studied by the absence of recombination as described in whiptail lizards. The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.

Yleaf: Software for Human Y-Chromosomal Haplogroup Inference from Next-Generation Sequencing Data.

Science.gov (United States)

Ralf, Arwin; Montiel González, Diego; Zhong, Kaiyin; Kayser, Manfred

2018-05-01

Next-generation sequencing (NGS) technologies offer immense possibilities given the large genomic data they simultaneously deliver. The human Y-chromosome serves as good example how NGS benefits various applications in evolution, anthropology, genealogy, and forensics. Prior to NGS, the Y-chromosome phylogenetic tree consisted of a few hundred branches, based on NGS data, it now contains many thousands. The complexity of both, Y tree and NGS data provide challenges for haplogroup assignment. For effective analysis and interpretation of Y-chromosome NGS data, we present Yleaf, a publically available, automated, user-friendly software for high-resolution Y-chromosome haplogroup inference independently of library and sequencing methods.

Chromosome 10q tetrasomy: First reported case

Energy Technology Data Exchange (ETDEWEB)

Blackston, R.D.; May, K.M.; Jones, F.D. [Emory Univ., Atlanta, GA (United States)] [and others

1994-09-01

While there are several reports of trisomy 10q (at least 35), we are not aware of previous cases of 10q tetrasomy. We present what we believe to be the initial report of such a case. R.J. is a 6 1/2 year old white male who presented with multiple dysmorphic features, marked articulation problems, hyperactivity, and developmental delays. He is the product of a term uncomplicated pregnancy. There was a normal spontaneous vaginal delivery with a birth weight of 6 lbs. 4oz. and length was 19 1/2 inch. Dysmorphic features include small size, an asymmetrically small head, low set ears with overfolded helixes, bilateral ptosis, downslanting eyes, right eye esotropia, prominent nose, asymmetric facies, high palate, mild pectus excavatum deformity of chest, and hyperextensible elbow joints. The patient is in special needs classes for mildly mentally handicapped students. Chromosome analysis at a resolution of 800 bands revealed a complex rearrangement of chromosomes 10 and 11. The segment 10q25.3 to q16.3 appears to be inverted and duplicated within the long arm of chromosome 10 at band q25.3 and the same segment of chromosome 10 is present on the terminal end of the short arm of chromosome 11. There is no visible loss of material from chromosome 11. Fluorescence in situ hybridization was performed with a chromosome 10 specific {open_quotes}paint{close_quotes} to confirm that all of the material on the abnormal 10 and the material on the terminal short arm of 11 was from chromosome 10. Thus, it appears that the segment 10q25.3 to q26.3 is present in four copies. Parental chromosome studies are normal. We compared findings which differ in that the case of 10q tetrasomy did not have prenatal growth deficiency, microphthalmia, cleft palate, digital anomalies, heart, or renal defects. Whereas most cases of 10q trisomy are said to have severe mental deficiency, our case of 10q tetrasomy was only mildly delayed. We report this first apparent cited case of 10q tetrasomy.

An international study of intrachromosomal amplification of chromosome 21 (iAMP21): cytogenetic characterization and outcome

Science.gov (United States)

Harrison, CJ; Moorman, AV; Schwab, C; Carroll, AJ; Raetz, EA; Devidas, M; Strehl, S; Nebral, K; Harbott, J; Teigler-Schlegel, A; Zimmerman, M; Dastuge, N; Baruchel, A; Soulier, J; Auclerc, M-F; Attarbaschi, A; Mann, G; Stark, B; Cazzaniga, G; Chilton, L; Vandenberghe, P; Forestier, E; Haltrich, I; Raimondi, SC; Parihar, M; Bourquin, J-P; Tchinda, J; Haferlach, C; Vora, A; Hunger, SP; Heerema, NA; Haas, OA

2014-01-01

Intrachromosomal amplification of chromosome 21 (iAMP21) defines a distinct cytogenetic subgroup of childhood B-cell precursor acute lymphoblastic leukaemia (BCP-ALL). To date, fluorescence in situ hybridisation (FISH), with probes specific for the RUNX1 gene, provides the only reliable detection method (five or more RUNX1 signals per cell). Patients with iAMP21 are older (median age 9 years) with a low white cell count. Previously, we demonstrated a high relapse risk when these patients were treated as standard risk. Recent studies have shown improved outcome on intensive therapy. In view of these treatment implications, accurate identification is essential. Here we have studied the cytogenetics and outcome of 530 iAMP21 patients that highlighted the association of specific secondary chromosomal and genetic changes with iAMP21 to assist in diagnosis, including the gain of chromosome X, loss or deletion of chromosome 7, ETV6 and RB1 deletions. These iAMP21 patients when treated as high risk showed the same improved outcome as those in trial-based studies regardless of the backbone chemotherapy regimen given. This study reinforces the importance of intensified treatment to reduce the risk of relapse in iAMP21 patients. This now well-defined patient subgroup should be recognised by World Health Organisation (WHO) as a distinct entity of BCP-ALL. PMID:24166298

Sperm FISH analysis of a 44,X,der(Y),t(Y;15)(q12;q10)pat,rob(13;14)(q10;q10)mat complex chromosome rearrangement.

Science.gov (United States)

Ferfouri, F; Boitrelle, F; Clement, P; Molina Gomes, D; Selva, J; Vialard, F

2014-06-01

Complex chromosome rearrangements (CCR) with two independent chromosome rearrangements are rare. Although CCRs lead to high unbalanced gamete rates, data on meiotic segregation in this context are scarce. A male patient was referred to our clinic as part of a family screening programme prompted by the observation of a 44,X,der(Y),t(Y;15)(q12;q10)pat,rob(13;14)(q10;q10)mat karyotype in his brother. Karyotyping identified the same CCR. Sperm FISH (with locus-specific probes for the segments involved in the translocations and nine chromosomes not involved in both rearrangements) was used to investigate the rearrangements meiotic segregation products and establish whether or not an inter-chromosomal effect was present. Sperm nuclear DNA fragmentation was also evaluated. For rob(13;14) and der(Y), the proportions of unbalanced products were, respectively, 26.4% and 60.6%. Overall, 70.3% of the meiotic segregation products were unbalanced. No evidence of an inter-chromosomal effect was found, and the sperm nuclear DNA fragmentation rate was similar to our laboratory's normal cut-off value. In view of previously published sperm FISH analyses of Robertsonian translocations (and even though the mechanism is still unknown), we hypothesise that cosegregation of der(Y) and rob(13;14) could modify rob(13;14) meiotic segregation. © 2013 Blackwell Verlag GmbH.

Complex chromosomal rearrangement in a girl with psychomotor-retardation and a de novo inversion: inv(2)(p15;q24.2).

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Granot-Hershkovitz, Einat; Raas-Rothschild, Annick; Frumkin, Ayala; Granot, David; Silverstein, Shira; Abeliovich, Dvorah

2011-08-01

Cytogenetic analysis of DNA from a girl with severe psychomotor retardation revealed a de novo pericentric inversion of chromosome 2: 46,XX,inv(2)(p15q24.2). In order to elucidate the possible role of the inversion in the girl's abnormal phenotype, we analyzed the inversion breakpoints. FISH analysis revealed BAC clones spanning the breakpoints at 2p and 2q of the inversion. Southern blot hybridization with DNA probes from the BAC regions was used to refine the localization of the breakpoints, followed by inverse-PCR which enabled us to sequence the inversion breakpoints. We found a complex chromosomal rearrangement, including five breakpoints, four at 2q and one at 2p joined with minor insertions/deletions of a few bases. The breakpoint at 2p was within the NRXN1 gene that has previously been associated with autism, intellectual disabilities, and psychiatric disorders. In 2q, the breakpoints disrupted two genes, TANC1 and RBMS1; the phenotypic effect of these genes is not currently known. Copyright © 2011 Wiley-Liss, Inc.

Distinct modes of recruitment of the CCR4-NOT complex by Drosophila and vertebrate Nanos.

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Raisch, Tobias; Bhandari, Dipankar; Sabath, Kevin; Helms, Sigrun; Valkov, Eugene; Weichenrieder, Oliver; Izaurralde, Elisa

2016-05-02

Nanos proteins repress the expression of target mRNAs by recruiting effector complexes through non-conserved N-terminal regions. In vertebrates, Nanos proteins interact with the NOT1 subunit of the CCR4-NOT effector complex through a NOT1 interacting motif (NIM), which is absent in Nanos orthologs from several invertebrate species. Therefore, it has remained unclear whether the Nanos repressive mechanism is conserved and whether it also involves direct interactions with the CCR4-NOT deadenylase complex in invertebrates. Here, we identify an effector domain (NED) that is necessary for the Drosophila melanogaster (Dm) Nanos to repress mRNA targets. The NED recruits the CCR4-NOT complex through multiple and redundant binding sites, including a central region that interacts with the NOT module, which comprises the C-terminal domains of NOT1-3. The crystal structure of the NED central region bound to the NOT module reveals an unanticipated bipartite binding interface that contacts NOT1 and NOT3 and is distinct from the NIM of vertebrate Nanos. Thus, despite the absence of sequence conservation, the N-terminal regions of Nanos proteins recruit CCR4-NOT to assemble analogous repressive complexes. © 2016 The Authors. Published under the terms of the CC BY NC ND 4.0 license.

The Biological Effectiveness of Four Energies of Neon Ions for the Induction of Chromosome Damage in Human Lymphocytes

Science.gov (United States)

George, Kerry; Hada, Megumi; Cucinotta, F. A.

2011-01-01

Chromosomal aberrations were measured in human peripheral blood lymphocytes after in vitro exposure to neon ions at energies of 64, 89, 142, or 267. The corresponding LET values for these energies of neon ranged from 38-103 keV/micrometers and doses delivered were in the 10 to 80 cGy range. Chromosome exchanges were assessed in metaphase and G2 phase cells at first division after exposure using fluorescence in situ hybridization (FISH) with whole chromosome probes and dose response curves were generated for different types of chromosomal exchanges. The yields of total chromosome exchanges were similar for the 64, 89, and 142 MeV exposures, whereas the 267 MeV/u neon with LET of 38 keV/micrometers produced about half as many exchanges per unit dose. The induction of complex type chromosome exchanges (exchanges involving three or more breaks and two or more chromosomes) showed a clear LET dependence for all energies. The ratio of simple to complex type exchanges increased with LET from 18 to 51%. The relative biological effectiveness (RBE) was estimated from the initial slope of the dose response curve for chromosome damage with respect to gamma-rays. The RBE(sub max) values for total chromosome exchanges for the 64 MeV/u was around 30.

The functional role for condensin in the regulation of chromosomal organization during the cell cycle.

Science.gov (United States)

Kagami, Yuya; Yoshida, Kiyotsugu

2016-12-01

In all organisms, the control of cell cycle progression is a fundamental process that is essential for cell growth, development, and survival. Through each cell cycle phase, the regulation of chromatin organization is essential for natural cell proliferation and maintaining cellular homeostasis. During mitosis, the chromatin morphology is dramatically changed to have a "thread-like" shape and the condensed chromosomes are segregated equally into two daughter cells. Disruption of the mitotic chromosome architecture physically impedes chromosomal behaviors, such as chromosome alignment and chromosome segregation; therefore, the proper mitotic chromosome structure is required to maintain chromosomal stability. Accumulating evidence has demonstrated that mitotic chromosome condensation is induced by condensin complexes. Moreover, recent studies have shown that condensin also modulates interphase chromatin and regulates gene expression. This review mainly focuses on the molecular mechanisms that condensin uses to exert its functions during the cell cycle progression. Moreover, we discuss the condensin-mediated chromosomal organization in cancer cells.

Vibrio chromosome-specific families

DEFF Research Database (Denmark)

Lukjancenko, Oksana; Ussery, David

2014-01-01

We have compared chromosome-specific genes in a set of 18 finished Vibrio genomes, and, in addition, also calculated the pan- and core-genomes from a data set of more than 250 draft Vibrio genome sequences. These genomes come from 9 known species and 2 unknown species. Within the finished...... chromosomes, we find a core set of 1269 encoded protein families for chromosome 1, and a core of 252 encoded protein families for chromosome 2. Many of these core proteins are also found in the draft genomes (although which chromosome they are located on is unknown.) Of the chromosome specific core protein...... families, 1169 and 153 are uniquely found in chromosomes 1 and 2, respectively. Gene ontology (GO) terms for each of the protein families were determined, and the different sets for each chromosome were compared. A total of 363 different "Molecular Function" GO categories were found for chromosome 1...

Dynamic chromosomal rearrangements in Hodgkin's lymphoma are due to ongoing three-dimensional nuclear remodeling and breakage-bridge-fusion cycles.

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Guffei, Amanda; Sarkar, Rahul; Klewes, Ludger; Righolt, Christiaan; Knecht, Hans; Mai, Sabine

2010-12-01

Hodgkin's lymphoma is characterized by the presence of mono-nucleated Hodgkin cells and bi- to multi-nucleated Reed-Sternberg cells. We have recently shown telomere dysfunction and aberrant synchronous/asynchronous cell divisions during the transition of Hodgkin cells to Reed-Sternberg cells.1 To determine whether overall changes in nuclear architecture affect genomic instability during the transition of Hodgkin cells to Reed-Sternberg cells, we investigated the nuclear organization of chromosomes in these cells. Three-dimensional fluorescent in situ hybridization revealed irregular nuclear positioning of individual chromosomes in Hodgkin cells and, more so, in Reed-Sternberg cells. We characterized an increasingly unequal distribution of chromosomes as mono-nucleated cells became multi-nucleated cells, some of which also contained chromosome-poor 'ghost' cell nuclei. Measurements of nuclear chromosome positions suggested chromosome overlaps in both types of cells. Spectral karyotyping then revealed both aneuploidy and complex chromosomal rearrangements: multiple breakage-bridge-fusion cycles were at the origin of the multiple rearranged chromosomes. This conclusion was challenged by super resolution three-dimensional structured illumination imaging of Hodgkin and Reed-Sternberg nuclei. Three-dimensional super resolution microscopy data documented inter-nuclear DNA bridges in multi-nucleated cells but not in mono-nucleated cells. These bridges consisted of chromatids and chromosomes shared by two Reed-Sternberg nuclei. The complexity of chromosomal rearrangements increased as Hodgkin cells developed into multi-nucleated cells, thus indicating tumor progression and evolution in Hodgkin's lymphoma, with Reed-Sternberg cells representing the highest complexity in chromosomal rearrangements in this disease. This is the first study to demonstrate nuclear remodeling and associated genomic instability leading to the generation of Reed-Sternberg cells of Hodgkin's lymphoma

Spatial positioning of all 24 chromosomes in the lymphocytes of six subjects: evidence of reproducible positioning and spatial repositioning following DNA damage with hydrogen peroxide and ultraviolet B.

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Dimitrios Ioannou

Full Text Available The higher-order organization of chromatin is well-established, with chromosomes occupying distinct positions within the interphase nucleus. Chromatin is susceptible to, and constantly assaulted by both endogenous and exogenous threats. However, the effects of DNA damage on the spatial topology of chromosomes are hitherto, poorly understood. This study investigates the organization of all 24 human chromosomes in lymphocytes from six individuals prior to- and following in-vitro exposure to genotoxic agents: hydrogen peroxide and ultraviolet B. This study is the first to report reproducible distinct hierarchical radial organization of chromosomes with little inter-individual differences between subjects. Perturbed nuclear organization was observed following genotoxic exposure for both agents; however a greater effect was observed for hydrogen peroxide including: 1 More peripheral radial organization; 2 Alterations in the global distribution of chromosomes; and 3 More events of chromosome repositioning (18 events involving 10 chromosomes vs. 11 events involving 9 chromosomes for hydrogen peroxide and ultraviolet B respectively. Evidence is provided of chromosome repositioning and altered nuclear organization following in-vitro exposure to genotoxic agents, with notable differences observed between the two investigated agents. Repositioning of chromosomes following genotoxicity involved recurrent chromosomes and is most likely part of the genomes inherent response to DNA damage. The variances in nuclear organization observed between the two agents likely reflects differences in mobility and/or decondensation of chromatin as a result of differences in the type of DNA damage induced, chromatin regions targeted, and DNA repair mechanisms.

RAD21L, a novel cohesin subunit implicated in linking homologous chromosomes in mammalian meiosis.

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Lee, Jibak; Hirano, Tatsuya

2011-01-24

Cohesins are multi-subunit protein complexes that regulate sister chromatid cohesion during mitosis and meiosis. Here we identified a novel kleisin subunit of cohesins, RAD21L, which is conserved among vertebrates. In mice, RAD21L is expressed exclusively in early meiosis: it apparently replaces RAD21 in premeiotic S phase, becomes detectable on the axial elements in leptotene, and stays on the axial/lateral elements until mid pachytene. RAD21L then disappears, and is replaced with RAD21. This behavior of RAD21L is unique and distinct from that of REC8, another meiosis-specific kleisin subunit. Remarkably, the disappearance of RAD21L at mid pachytene correlates with the completion of DNA double-strand break repair and the formation of crossovers as judged by colabeling with molecular markers, γ-H2AX, MSH4, and MLH1. RAD21L associates with SMC3, STAG3, and either SMC1α or SMC1β. Our results suggest that cohesin complexes containing RAD21L may be involved in synapsis initiation and crossover recombination between homologous chromosomes.

Giemsa C-banding of Barley Chromosomes. IV. Chromosomal Constitution of Autotetraploid Barley

DEFF Research Database (Denmark)

Linde-Laursen, Ib

1984-01-01

The progeny of an autotetraploid barley plant (C1) consisted of 45 tetraploids and 33 aneuploids. Giemsa C-banding was used to identify each of the chromosomes in 20 euploid and 31 aneuploid C2--seedlings, and in 11 C3--offspring of aneuploid C2--plants. The euploid C2--seedlings all had four...... homologues of each of the chromosomes. The aneuploid C2--seedlings were fairly equally distributed on hypo-and hyperploids, and on the seven chromosome groups. This suggests that a particular chromosome is lost or gained at random in gametes and embryos. The 11 C3--seedlings comprised seven true euploids......, one seedling with 2n=28 having an extra chromosome 6 and missing one chromosome 3, and three seedlings with 2n=29. The chromosomal composition of aneuploid C3--seedlings did not reflect that of their aneuploid C2--parents with respect to missing or extra chromosomes. Two hypohexaploid C2--seedlings...

Is 24-color FISH detection of in-vitro radiation-induced chromosomal aberrations suited to determine individual intrinsic radiosensitivity?

International Nuclear Information System (INIS)

Kuechler, A.; Wendt, T.G.; Neubauer, S.; Grabenbauer, G.G.; Sauer, R.; Claussen, U.; Liehr, T.

2002-01-01

Background: Reliable determination of intrinsic radiosensitivity in individual patients is a serious need in radiation oncology. Chromosomal aberrations are sensitive indicators of a previous exposure to ionizing irradiation. Former molecular cytogenetic studies showed that such aberrations as an equivalent of intrinsic radiosensitivity can be detected by fluorescence in-situ hybridization (FISH) techniques using whole chromosome painting (wcp) probes. However, only one up to three randomly chosen wcp probes have been applied for such approaches until now. As a random distribution of chromosomal rearrangements along the chromosomes is up to now still controversial, the power of the 24-color FISH approach should be elucidated in the present study. Methods and Material: Lymphocytes derived from lymphoblastoid cell lines of one patient with Nijmegen breakage syndrome (NBS homozygote) and of two NBS heterozygotes and peripheral blood lymphocytes of two controls were analyzed. Samples of each patient/control were irradiated in vitro with 0.0 Gy, 0.7 Gy or 2.0 Gy prior to cultivation. Chromosomal aberrations were analyzed in detail and quantified by means of 24-color FISH as an expression of the individual intrinsic radiosensitivity. Results: 24-color FISH analyses were done in a total of 1,674 metaphases. After in-vitro irradiation, 21% (0.7 Gy) or 57% (2.0 Gy) of the controls' cells, 15% (0.7 Gy) or 53% (2.0 Gy) of the heterozygotes' cells and 54% (0.7 Gy) or 79% (2.0 Gy) of the homozygote's cells contained aberrations. The highest average rates of breaks per mitosis [B/M] (0.7 Gy: 1.80 B/M, 2.0 Gy: 4.03 B/M) and complex chromosomal rearrangements [CCR] (0.7 Gy: 0.20 CCR/M, 2.0 Gy: 0.47 CCR/M) were observed in the NBS patient. Moreover, the proportion of different aberration types after irradiation showed a distinct increase in the rate of CCR combined with a decrease in dicentrics in the NBS homozygote. Conclusion: To come to a more complete picture of radiation

Deletions at chromosome regions 7q11.23 and 7q36 in a patient with Williams syndrome

NARCIS (Netherlands)

Wouters, C. H.; Meijers-Heijboer, H. J.; Eussen, B. J.; van der Heide, A. A.; van Luijk, R. B.; van Drunen, E.; Beverloo, B. B.; Visscher, F.; van Hemel, J. O.

2001-01-01

We report on a patient with Williams syndrome and a complex de novo chromosome rearrangement, including microdeletions at 7q11.23 and 7q36 and additional chromosomal material at 7q36. The nature of this additional material was elucidated by spectral karyotyping and first assigned to chromosome 22.

On Hobbes’s distinction of accidents

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Lupoli Agostino

2012-06-01

Full Text Available An interpolation introduced by K. Schuhmann in his critical edition of "De corpore" (chap. VI, § 13 diametrically overturns the meaning of Hobbes’s doctrine of distinction of accidents in comparison with all previous editions. The article focuses on the complexity of this crucial juncture in "De corpore" argument on which depends the interpretation of Hobbes’s whole conception of science. It discusses the reasons pro and contra Schuhmann’s interpolation and concludes against it, because it is not compatible with the rationale underlying the complex architecture of "De corpore", which involves a symmetry between the ‘logical’ distinction of accidents and the ‘metaphysical’ distinction of phantasms.

Automatic aberration scoring using whole chromosome F.I.S.H

International Nuclear Information System (INIS)

Piper, J.; Bayley, R.; Boyle, S.; Fantes, J.A.; Green, D.K.; Gordon, J.; Hill, W.; Ji, L.; Malloy, P.; Perry, P.; Rutovitz, D.; Stark, M.; Whale, D.

1993-01-01

A radiation-induced rearrangement involving a painted and a non-painted chromosome will usually result in two partly-painted chromosomes, typically either a dicentric chromosome and associated fragment, or a reciprocal translocation pair. A consequence of such a rearrangement is that the number of painted image regions in the metaphase is increased by one, and their size distribution is altered. More complex rearrangements are uncommon, particularly at low doses. A high proportion of damaged cells can therefore be registered simply by detecting when the distribution of painted components differs from the expected number and size. A system has been constructed to pre-screen for damaged cells. It comprises automatic fluorescence metaphase finding followed by relocation and digitization of probe and counterstain channels at high resolution. Fully automatic segmentation in counterstain discriminates chromosomes from interphase nuclei and determines whether a metaphase is approximately diploid. The painted regions are segmented and their relative sizes estimated. Rules are applied which reduce the false positives due to artifacts such as overlapped painted chromosomes. More than 70% of cells with radiation damage involving painted and unpainted chromosomes were detected in a preliminary experiment using a small data set, with a low false positive rate. Results from a larger experiment in progress are presented

Sister chromosome pairing maintains heterozygosity in parthenogenetic lizards.

Science.gov (United States)

Lutes, Aracely A; Neaves, William B; Baumann, Diana P; Wiegraebe, Winfried; Baumann, Peter

2010-03-11

Although bisexual reproduction has proven to be highly successful, parthenogenetic all-female populations occur frequently in certain taxa, including the whiptail lizards of the genus Aspidoscelis. Allozyme analysis revealed a high degree of fixed heterozygosity in these parthenogenetic species, supporting the view that they originated from hybridization events between related sexual species. It has remained unclear how the meiotic program is altered to produce diploid eggs while maintaining heterozygosity. Here we show that meiosis commences with twice the number of chromosomes in parthenogenetic versus sexual species, a mechanism that provides the basis for generating gametes with unreduced chromosome content without fundamental deviation from the classic meiotic program. Our observation of synaptonemal complexes and chiasmata demonstrate that a typical meiotic program occurs and that heterozygosity is not maintained by bypassing recombination. Instead, fluorescent in situ hybridization probes that distinguish between homologues reveal that bivalents form between sister chromosomes, the genetically identical products of the first of two premeiotic replication cycles. Sister chromosome pairing provides a mechanism for the maintenance of heterozygosity, which is critical for offsetting the reduced fitness associated with the lack of genetic diversity in parthenogenetic species.

Distamycin A/DAPI bands and the effects of 5-azacytidine on the chromosomes of the chimpanzee, Pan troglodytes.

Science.gov (United States)

Schmid, M; Haaf, T

1984-01-01

The chromosomes of the chimpanzee were stained with distamycin A/DAPI, which labels specific C-bands. Bright distamycin A/DAPI fluorescence was found in the heterochromatic regions of chromosomes 6, 11, 14 to 16, 18 to 20, and 23 and the Y. Lymphocyte cultures from chimpanzees were treated with low doses of 5-azacytidine during the last hours of culture. This cytosine analog induces highly distinct undercondensations in 28 heterochromatic regions of 19 chromosomes. These 5-azacytidine-sensitive regions are predominantly located in the terminal C-bands of the chromosomes. In vitro treatment with 5-azacytidine also preserves into the metaphase stage somatic pairings between the 5-azacytidine-sensitive heterochromatic regions in interphase nuclei. The homologies and differences regarding the chromosomal localization of distamycin A/DAPI-bright C-bands, 5-azacytidine-sensitive heterochromatin, 5-methylcytosine-rich DNA sequences, and satellite DNAs in the chimpanzee and man are discussed.

SMC Progressively Aligns Chromosomal Arms in Caulobacter crescentus but Is Antagonized by Convergent Transcription

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Ngat T. Tran

2017-08-01

Full Text Available The structural maintenance of chromosomes (SMC complex plays an important role in chromosome organization and segregation in most living organisms. In Caulobacter crescentus, SMC is required to align the left and the right arms of the chromosome that run in parallel down the long axis of the cell. However, the mechanism of SMC-mediated alignment of chromosomal arms remains elusive. Here, using genome-wide methods and microscopy of single cells, we show that Caulobacter SMC is recruited to the centromeric parS site and that SMC-mediated arm alignment depends on the chromosome-partitioning protein ParB. We provide evidence that SMC likely tethers the parS-proximal regions of the chromosomal arms together, promoting arm alignment. Furthermore, we show that highly transcribed genes near parS that are oriented against SMC translocation disrupt arm alignment, suggesting that head-on transcription interferes with SMC translocation. Our results demonstrate a tight interdependence of bacterial chromosome organization and global patterns of transcription.

Shelterin Protects Chromosome Ends by Compacting Telomeric Chromatin

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Bandaria, Jigar N.; Qin, Peiwu; Berk, Veysel; Chu, Steven; Yildiz, Ahmet

2016-01-01

SUMMARY Telomeres, repetitive DNA sequences at chromosome ends, are shielded against the DNA damage response (DDR) by the shelterin complex. To understand how shelterin protects telomere ends, we investigated the structural organization of telomeric chromatin in human cells using super-resolution microscopy. We found that telomeres form compact globular structures through a complex network of interactions between shelterin subunits and telomeric DNA, and not by DNA methylation, histone deacetylation or histone trimethylation at telomeres and subtelomeric regions. Mutations that abrogate shelterin assembly or removal of individual subunits from telomeres cause up to a 10-fold increase in telomere volume. Decompacted telomeres become more accessible to telomere-associated proteins and accumulate DDR signals. Recompaction of telomeric chromatin using an orthogonal method displaces DDR signals from telomeres. These results reveal the chromatin remodeling activity of shelterin and demonstrate that shelterin-mediated compaction of telomeric chromatin provides robust protection of chromosome ends against the DDR machinery. PMID:26871633

Recombination Proteins Mediate Meiotic Spatial Chromosome Organization and Pairing

Science.gov (United States)

Storlazzi, Aurora; Gargano, Silvana; Ruprich-Robert, Gwenael; Falque, Matthieu; David, Michelle; Kleckner, Nancy; Zickler, Denise

2010-01-01

SUMMARY Meiotic chromosome pairing involves not only recognition of homology but also juxtaposition of entire chromosomes in a topologically regular way. Analysis of filamentous fungus Sordaria macrospora reveals that recombination proteins Mer3, Msh4 and Mlh1 play direct roles in all of these aspects, in advance of their known roles in recombination. Absence of Mer3 helicase results in interwoven chromosomes, thereby revealing the existence of features that specifically ensure “entanglement avoidance”. Entanglements that remain at zygotene, i.e. “interlockings”, require Mlh1 for resolution, likely to eliminate constraining recombinational connections. Patterns of Mer3 and Msh4 foci along aligned chromosomes show that the double-strand breaks mediating homologous alignment have spatially separated ends, one localized to each partner axis, and that pairing involves interference among developing interhomolog interactions. We propose that Mer3, Msh4 and Mlh1 execute all of these roles during pairing by modulating the state of nascent double-strand break/partner DNA contacts within axis-associated recombination complexes. PMID:20371348

Accelerated pseudogenization on the neo-X chromosome in Drosophila miranda

KAUST Repository

Nozawa, Masafumi

2016-11-29

Y chromosomes often degenerate via the accumulation of pseudogenes and transposable elements. By contrast, little is known about X-chromosome degeneration. Here we compare the pseudogenization process between genes on the neo-sex chromosomes in Drosophila miranda and their autosomal orthologues in closely related species. The pseudogenization rate on the neo-X is much lower than the rate on the neo-Y, but appears to be higher than the rate on the orthologous autosome in D. pseudoobscura. Genes under less functional constraint and/or genes with male-biased expression tend to become pseudogenes on the neo-X, indicating the accumulation of slightly deleterious mutations and the feminization of the neo-X. We also find a weak trend that the genes with female-benefit/male-detriment effects identified in D. melanogaster are pseudogenized on the neo-X, implying the masculinization of the neo-X. These observations suggest that both X and Y chromosomes can degenerate due to a complex suite of evolutionary forces.

X chromosome and suicide.

Science.gov (United States)

Fiori, L M; Zouk, H; Himmelman, C; Turecki, G

2011-02-01

Suicide completion rates are significantly higher in males than females in most societies. Although gender differences in suicide rates have been partially explained by environmental and behavioral factors, it is possible that genetic factors, through differential expression between genders, may also help explain gender moderation of suicide risk. This study investigated X-linked genes in suicide completers using a two-step strategy. We first took advantage of the genetic structure of the French-Canadian population and genotyped 722 unrelated French-Canadian male subjects, of whom 333 were suicide completers and 389 were non-suicide controls, using a panel of 37 microsatellite markers spanning the entire X chromosome. Nine haplotype windows and several individual markers were associated with suicide. Significant results aggregated primarily in two regions, one in the long arm and another in the short arm of chromosome X, limited by markers DXS8051 and DXS8102, and DXS1001 and DXS8106, respectively. The second stage of the study investigated differential brain expression of genes mapping to associated regions in Brodmann areas 8/9, 11, 44 and 46, in an independent sample of suicide completers and controls. Six genes within these regions, Rho GTPase-activating protein 6, adaptor-related protein complex 1 sigma 2 subunit, glycoprotein M6B, ribosomal protein S6 kinase 90  kDa polypeptide 3, spermidine/spermine N(1)-acetyltransferase 1 and THO complex 2, were found to be differentially expressed in suicide completers.

Discrimination of chromosome by autoradiography

International Nuclear Information System (INIS)

Masubuchi, Masanori

1975-01-01

This paper describes discrimination of chromosome by autoradiography. In this method, the difference in DNA synthetic phase between each chromosome was used as a standard, and the used chromosome was in metaphase, as morphological characteristics were markedly in this phase. Cell cycle and autoradiography with 3 H-thymidine were also examined. In order to discriminate chromosome by autoradiography, it was effective to utilize the labelled pattern in late DNA synthetic phase, where asynchronous replication of chromosome appeared most obviously. DNA synthesis in chromosome was examined in each DNA synthetic phase by culturing the chromosome after the treatment with 3 H-thymidine and altering the time to prepare chromosome specimen. Discrimination of chromosome in plants and animals by autoradiography was also mentioned. It was noticed as a structural and functional discrimination of chromosome to observe amino acid uptake into chromosome protein and to utilize the difference in labelled pattern between the sites of chromosome. (K. Serizawa)

Interdependency and phosphorylation of KIF4 and condensin I are essential for organization of chromosome scaffold.

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Rawin Poonperm

Full Text Available Kinesin family member 4 (KIF4 and condensins I and II are essential chromosomal proteins for chromosome organization by locating primarily to the chromosome scaffold. However, the mechanism of how KIF4 and condensins localize to the chromosome scaffold is poorly understood. Here, we demonstrate a close relationship between the chromosome localization of KIF4 and condensin I, but not condensin II, and show that KIF4 and condensin I assist each other for stable scaffold formation by forming a stable complex. Moreover, phosphorylation of KIF4 and condensin I by Aurora B and polo-like kinase 1 (Plk1 is important for KIF4 and condensin I localization to the chromosome. Aurora B activity facilitates the targeting of KIF4 and condensin I to the chromosome, whereas Plk1 activity promotes the dissociation of these proteins from the chromosome. Thus, the interdependency between KIF4 and condensin I, and their phosphorylation states play important roles in chromosome scaffold organization during mitosis.

Interdependency and phosphorylation of KIF4 and condensin I are essential for organization of chromosome scaffold.

Science.gov (United States)

Poonperm, Rawin; Takata, Hideaki; Uchiyama, Susumu; Fukui, Kiichi

2017-01-01

Kinesin family member 4 (KIF4) and condensins I and II are essential chromosomal proteins for chromosome organization by locating primarily to the chromosome scaffold. However, the mechanism of how KIF4 and condensins localize to the chromosome scaffold is poorly understood. Here, we demonstrate a close relationship between the chromosome localization of KIF4 and condensin I, but not condensin II, and show that KIF4 and condensin I assist each other for stable scaffold formation by forming a stable complex. Moreover, phosphorylation of KIF4 and condensin I by Aurora B and polo-like kinase 1 (Plk1) is important for KIF4 and condensin I localization to the chromosome. Aurora B activity facilitates the targeting of KIF4 and condensin I to the chromosome, whereas Plk1 activity promotes the dissociation of these proteins from the chromosome. Thus, the interdependency between KIF4 and condensin I, and their phosphorylation states play important roles in chromosome scaffold organization during mitosis.

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

complex, unlike at other parts of the genome, such as CG-rich regions, where Jarid2 and PRC2 binding are interdependent. Conversely, we show that Jarid2 loss prevents efficient PRC2 and H3K27me3 enrichment to Xist-coated chromatin. Jarid2 thus represents an important intermediate between PRC2 and Xist RNA......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...... for the initial targeting of the PRC2 complex to the X chromosome during onset of XCI....

The Y chromosome of the Atelidae family (Platyrrhini): study by chromosome microdissection.

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Gifalli-Iughetti, C; Koiffmann, C P

2009-01-01

In order to study the intergeneric variability of the Y chromosome, we describe the hybridization of the Y chromosome of Brachytelesarachnoides, obtained by microdissection, to metaphases of Atelesbelzebuthmarginatus, Lagothrixlagothricha, and Alouatta male specimens. Brachytelesarachnoides (Atelinae) has 62 chromosomes and a very small Y chromosome. Our results showed that the Brachytelesarachnoides Y chromosome probe hybridized to Lagothrixlagothricha metaphases yielding one hybridization signal on only the tiny Y chromosome, and when hybridized with Atelesbelzebuthmarginatus metaphases it yielded one hybridization signal on two thirds of the small acrocentric Y chromosome. However, no hybridization signal was observed in Alouatta metaphases (subfamily Alouattinae), a closely related genus in the Atelidae family. Furthermore, our data support a close phylogenetic relationship among Brachyteles, Ateles, and Lagothrix and their placement in the Atelinae subfamily, but exclude Alouatta from this group indicating its placement as basal to this group. Copyright 2009 S. Karger AG, Basel.

The terminal region of the E. coli chromosome localises at the periphery of the nucleoid

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Stouf Mathieu

2011-02-01

Full Text Available Abstract Background Bacterial chromosomes are organised into a compact and dynamic structures termed nucleoids. Cytological studies in model rod-shaped bacteria show that the different regions of the chromosome display distinct and specific sub-cellular positioning and choreographies during the course of the cell cycle. The localisation of chromosome loci along the length of the cell has been described. However, positioning of loci across the width of the cell has not been determined. Results Here, we show that it is possible to assess the mean positioning of chromosomal loci across the width of the cell using two-dimension images from wide-field fluorescence microscopy. Observed apparent distributions of fluorescent-tagged loci of the E. coli chromosome along the cell diameter were compared with simulated distributions calculated using a range of cell width positioning models. Using this method, we detected the migration of chromosome loci towards the cell periphery induced by production of the bacteriophage T4 Ndd protein. In the absence of Ndd production, loci outside the replication terminus were located either randomly along the nucleoid width or towards the cell centre whereas loci inside the replication terminus were located at the periphery of the nucleoid in contrast to other loci. Conclusions Our approach allows to reliably observing the positioning of chromosome loci along the width of E. coli cells. The terminal region of the chromosome is preferentially located at the periphery of the nucleoid consistent with its specific roles in chromosome organisation and dynamics.

Sequential actin-based pushing forces drive meiosis I chromosome migration and symmetry breaking in oocytes

Science.gov (United States)

Yi, Kexi; Rubinstein, Boris; Unruh, Jay R.; Guo, Fengli; Slaughter, Brian D.

2013-01-01

Polar body extrusion during oocyte maturation is critically dependent on asymmetric positioning of the meiotic spindle, which is established through migration of the meiosis I (MI) spindle/chromosomes from the oocyte interior to a subcortical location. In this study, we show that MI chromosome migration is biphasic and driven by consecutive actin-based pushing forces regulated by two actin nucleators, Fmn2, a formin family protein, and the Arp2/3 complex. Fmn2 was recruited to endoplasmic reticulum structures surrounding the MI spindle, where it nucleated actin filaments to initiate an initially slow and poorly directed motion of the spindle away from the cell center. A fast and highly directed second migration phase was driven by actin-mediated cytoplasmic streaming and occurred as the chromosomes reach a sufficient proximity to the cortex to activate the Arp2/3 complex. We propose that decisive symmetry breaking in mouse oocytes results from Fmn2-mediated perturbation of spindle position and the positive feedback loop between chromosome signal-induced Arp2/3 activation and Arp2/3-orchestrated cytoplasmic streaming that transports the chromosomes. PMID:23439682

Chromosomal instability can be induced by the formation of breakage-prone chromosome rearrangement junctions

International Nuclear Information System (INIS)

Allen, R.N.; Ritter, L.; Moore, S.R.; Grosovsky, A.J.

2003-01-01

Full text: Studies in our lab have led to the hypothesis that chromosomal rearrangements can generate novel breakage-prone sites, resulting in chromosomal instability acting predominantly in cis. For example, specific breakage of large blocks of centromeric region heterochromatin on chromosome 16q by treatment with 2,6-diaminopurine (DAP) is associated with repeated rearrangement of chromosome 16q during outgrowth of DAP-treated clones, thereby establishing a link between the initial site of damage and the occurrence of persistent chromosomal instability. Similarly, karyotypic analysis of gamma ray induced instability demonstrated that chromosomal rearrangements in sub-clones were significantly clustered near the site of previously identified chromosomal rearrangement junctions in unstable parental clones. This study investigates the hypothesis that integration of transfected sequences into host chromosomes could create breakage-prone junction regions and persistent genomic instability without exposure to DNA-damage agents. These junctions may mimic the unstable chromosomal rearrangements induced by DAP or radiation, and thus provide a test of the broader hypothesis that instability can to some extent be attributed to the formation of novel chromosomal breakage hot spots. These experiments were performed using human-hamster hybrid AL cells containing a single human chromosome 11, which was used to monitor instability in a chromosomal painting assay. AL cells were transfected with a 2.5 Kb fragment containing multiple copies of the 180 bp human alpha heterochromatic repeat, which resulted in chromosomal instability in 41% of the transfected clones. Parallel exposure to gamma-radiation resulted in a similar level of chromosomal instability, although control transfections with plasmid alone did not lead to karyotypic instability. Chromosomal instability induced by integration of alpha heterochromatic repeats was also frequently associated with delayed reproductive

Transcription-based model for the induction of chromosomal exchange events by ionising radiation

International Nuclear Information System (INIS)

Radford, I.A.

2003-01-01

The mechanistic basis for chromosomal aberration formation, following exposure of mammalian cells to ionising radiation, has long been debated. Although chromosomal aberrations are probably initiated by DNA double-strand breaks (DSB), little is understood about the mechanisms that generate and modulate DNA rearrangement. Based on results from our laboratory and data from the literature, a novel model of chromosomal aberration formation has been suggested (Radford 2002). The basic postulates of this model are that: (1) DSB, primarily those involving multiple individual damage sites (i.e. complex DSB), are the critical initiating lesion; (2) only those DSB occurring in transcription units that are associated with transcription 'factories' (complexes containing multiple transcription units) induce chromosomal exchange events; (3) such DSB are brought into contact with a DNA topoisomerase I molecule through RNA polymerase II catalysed transcription and give rise to trapped DNA-topo I cleavage complexes; and (4) trapped complexes interact with another topo I molecule on a temporarily inactive transcription unit at the same transcription factory leading to DNA cleavage and subsequent strand exchange between the cleavage complexes. We have developed a method using inverse PCR that allows the detection and sequencing of putative ionising radiation-induced DNA rearrangements involving different regions of the human genome (Forrester and Radford 1998). The sequences detected by inverse PCR can provide a test of the prediction of the transcription-based model that ionising radiation-induced DNA rearrangements occur between sequences in active transcription units. Accordingly, reverse transcriptase PCR was used to determine if sequences involved in rearrangements were transcribed in the test cells. Consistent with the transcription-based model, nearly all of the sequences examined gave a positive result to reverse transcriptase PCR (Forrester and Radford unpublished)

ParABS Systems of the Four Replicons of Burkholderia cenocepacia: New Chromosome Centromeres Confer Partition Specificity†

Science.gov (United States)

Dubarry, Nelly; Pasta, Franck; Lane, David

2006-01-01

Most bacterial chromosomes carry an analogue of the parABS systems that govern plasmid partition, but their role in chromosome partition is ambiguous. parABS systems might be particularly important for orderly segregation of multipartite genomes, where their role may thus be easier to evaluate. We have characterized parABS systems in Burkholderia cenocepacia, whose genome comprises three chromosomes and one low-copy-number plasmid. A single parAB locus and a set of ParB-binding (parS) centromere sites are located near the origin of each replicon. ParA and ParB of the longest chromosome are phylogenetically similar to analogues in other multichromosome and monochromosome bacteria but are distinct from those of smaller chromosomes. The latter form subgroups that correspond to the taxa of their hosts, indicating evolution from plasmids. The parS sites on the smaller chromosomes and the plasmid are similar to the “universal” parS of the main chromosome but with a sequence specific to their replicon. In an Escherichia coli plasmid stabilization test, each parAB exhibits partition activity only with the parS of its own replicon. Hence, parABS function is based on the independent partition of individual chromosomes rather than on a single communal system or network of interacting systems. Stabilization by the smaller chromosome and plasmid systems was enhanced by mutation of parS sites and a promoter internal to their parAB operons, suggesting autoregulatory mechanisms. The small chromosome ParBs were found to silence transcription, a property relevant to autoregulation. PMID:16452432

SMC5/6 is required for the formation of segregation-competent bivalent chromosomes during meiosis I in mouse oocytes.

Science.gov (United States)

Hwang, Grace; Sun, Fengyun; O'Brien, Marilyn; Eppig, John J; Handel, Mary Ann; Jordan, Philip W

2017-05-01

SMC complexes include three major classes: cohesin, condensin and SMC5/6. However, the localization pattern and genetic requirements for the SMC5/6 complex during mammalian oogenesis have not previously been examined. In mouse oocytes, the SMC5/6 complex is enriched at the pericentromeric heterochromatin, and also localizes along chromosome arms during meiosis. The infertility phenotypes of females with a Zp3-Cre -driven conditional knockout (cKO) of Smc5 demonstrated that maternally expressed SMC5 protein is essential for early embryogenesis. Interestingly, protein levels of SMC5/6 complex components in oocytes decline as wild-type females age. When SMC5/6 complexes were completely absent in oocytes during meiotic resumption, homologous chromosomes failed to segregate accurately during meiosis I. Despite what appears to be an inability to resolve concatenation between chromosomes during meiosis, localization of topoisomerase IIα to bivalents was not affected; however, localization of condensin along the chromosome axes was perturbed. Taken together, these data demonstrate that the SMC5/6 complex is essential for the formation of segregation-competent bivalents during meiosis I, and findings suggest that age-dependent depletion of the SMC5/6 complex in oocytes could contribute to increased incidence of oocyte aneuploidy and spontaneous abortion in aging females. © 2017. Published by The Company of Biologists Ltd.

Micromechanics of human mitotic chromosomes

International Nuclear Information System (INIS)

Sun, Mingxuan; Kawamura, Ryo; Marko, John F

2011-01-01

Eukaryote cells dramatically reorganize their long chromosomal DNAs to facilitate their physical segregation during mitosis. The internal organization of folded mitotic chromosomes remains a basic mystery of cell biology; its understanding would likely shed light on how chromosomes are separated from one another as well as into chromosome structure between cell divisions. We report biophysical experiments on single mitotic chromosomes from human cells, where we combine micromanipulation, nano-Newton-scale force measurement and biochemical treatments to study chromosome connectivity and topology. Results are in accord with previous experiments on amphibian chromosomes and support the 'chromatin network' model of mitotic chromosome structure. Prospects for studies of chromosome-organizing proteins using siRNA expression knockdowns, as well as for differential studies of chromosomes with and without mutations associated with genetic diseases, are also discussed

Importance of No. 21 chromosome in translocation t(8:21) in acute myelocytic leukemia (AML) to the genesis of the disease

Energy Technology Data Exchange (ETDEWEB)

Ishihara, T; Minamihisamatsu, M

1986-05-01

The results are reported of the chromosome analysis of 17 cases of acute myelocytic leukemia (AML), mostly belonging to M2 of the FAB classification, especially on the translocation t(8:21) and its variant translocations. The presence of two cases with simple variant translocation not involving No. 8 chromosome seems to suggest that No. 21 chromosome is more important to the genesis of AML than the No. 8 chromosome. This assumption appears to be supported by findings on cases with complex translocation: In two cases with complex translocation, the portion translocated from No. 21 chromosome onto No. 8 was firmly maintained in the specific site (q21) on No. 8 whereas the portion translocated from No. 8 chromosome onto No. 21 was involved in further translocation with another chromosome, onto which it was re-translocated. The results of the present cytogenetic study indicate that the analysis of variant translocations in various specific chromosome translocations in leukemia and other malignant disorders is very useful to elucidate the problem as to whether the genesis of such disorders lies in either one or both of the pair of chromosomes involved in the specific translocations of the respective diseases.

Structural Chromosomal Alterations Induced by Dietary Bioflavonoids in Fanconi Anemia Lymphocytes

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Gonzalo Guevara

2007-06-01

Full Text Available IntroductionFanconi anemia is an autosomal recessive diseasecharacterized by a variety of congenital abnormalities,progressive bone marrow failure,increased chromosomal instability and higherrisk to acute myeloid leukemia, solid tumors. Thisentity can be considered an appropriate biologicalmodel to analyze natural substances with possiblegenotoxic effect. The aims of this study wereto describe and quantify structural chromosomalaberrations induced by 5 flavones, 2 isoflavonesand a topoisomerase II chemotherapeutic inhibitorin Fanconi anemia lymphocytes in order todetermine chromosomal numbers changes and/or type of chromosomal damage.Materials and methodsChromosomes stimulated by phytohaemagglutininM, from Fanconi anemia lymphocytes,were analysed by conventional cytogenetic culture.For each chemical substance and controls,one hundred metaphases were evaluated. Chromosomalalterations were documented by photographyand imaging analyzer. To statisticalanalysis was used chi square test to identify significantdifferences between frequencies of chromosomaldamage of basal and exposed cellcultured a P value less than 0.05.ResultsThere were 431 chromosomal alterations in1000 metaphases analysed; genistein was themore genotoxic bioflavonoid, followed in descendentorder by genistin, fisetin, kaempferol,quercetin, baicalein and miricetin. Chromosomalaberrations observed were: chromatidbreaks, chromosomal breaks, cromatid andchromosomal gaps, quadriratials exchanges,dicentrics chromosome and complex rearrangements.ConclusionBioflavonoids as genistein, genistin and fisetin,which are commonly present in the human diet,showed statistical significance in the number ofchromosomal aberrations in Fanconi anemialymphocytes, regarding the basal damage.

Is early-onset microsatellite and chromosomally stable colorectal cancer a hallmark of a genetic susceptibility syndrome?

NARCIS (Netherlands)

Kets, C.M.; Krieken, J.H.J.M. van; Erp, P.E.J. van; Feuth, T.; Jacobs, Y.H.A.; Brunner, H.G.; Ligtenberg, M.J.L.; Hoogerbrugge, N.

2008-01-01

Most colorectal cancers show either microsatellite or chromosomal instability. A subset of colorectal cancers, especially those diagnosed at young age, is known to show neither of these forms of genetic instability and thus might have a distinct pathogenesis. Colorectal cancers diagnosed at young

Mlh1 deficiency in normal mouse colon mucosa associates with chromosomally unstable colon cancer

Science.gov (United States)

Pussila, Marjaana; Törönen, Petri; Einarsdottir, Elisabet; Katayama, Shintaro; Krjutškov, Kaarel; Holm, Liisa; Kere, Juha; Peltomäki, Päivi; Mäkinen, Markus J; Linden, Jere; Nyström, Minna

2018-01-01

Abstract Colorectal cancer (CRC) genome is unstable and different types of instabilities, such as chromosomal instability (CIN) and microsatellite instability (MSI) are thought to reflect distinct cancer initiating mechanisms. Although 85% of sporadic CRC reveal CIN, 15% reveal mismatch repair (MMR) malfunction and MSI, the hallmarks of Lynch syndrome with inherited heterozygous germline mutations in MMR genes. Our study was designed to comprehensively follow genome-wide expression changes and their implications during colon tumorigenesis. We conducted a long-term feeding experiment in the mouse to address expression changes arising in histologically normal colonic mucosa as putative cancer preceding events, and the effect of inherited predisposition (Mlh1+/−) and Western-style diet (WD) on those. During the 21-month experiment, carcinomas developed mainly in WD-fed mice and were evenly distributed between genotypes. Unexpectedly, the heterozygote (B6.129-Mlh1tm1Rak) mice did not show MSI in their CRCs. Instead, both wildtype and heterozygote CRC mice showed a distinct mRNA expression profile and shortage of several chromosomal segregation gene-specific transcripts (Mlh1, Bub1, Mis18a, Tpx2, Rad9a, Pms2, Cenpe, Ncapd3, Odf2 and Dclre1b) in their colon mucosa, as well as an increased mitotic activity and abundant numbers of unbalanced/atypical mitoses in tumours. Our genome-wide expression profiling experiment demonstrates that cancer preceding changes are already seen in histologically normal colon mucosa and that decreased expressions of Mlh1 and other chromosomal segregation genes may form a field-defect in mucosa, which trigger MMR-proficient, chromosomally unstable CRC. PMID:29701748

Y-chromosome and mtDNA genetics reveal significant contrasts in affinities of modern Middle Eastern populations with European and African populations.

Science.gov (United States)

Badro, Danielle A; Douaihy, Bouchra; Haber, Marc; Youhanna, Sonia C; Salloum, Angélique; Ghassibe-Sabbagh, Michella; Johnsrud, Brian; Khazen, Georges; Matisoo-Smith, Elizabeth; Soria-Hernanz, David F; Wells, R Spencer; Tyler-Smith, Chris; Platt, Daniel E; Zalloua, Pierre A

2013-01-01

The Middle East was a funnel of human expansion out of Africa, a staging area for the Neolithic Agricultural Revolution, and the home to some of the earliest world empires. Post LGM expansions into the region and subsequent population movements created a striking genetic mosaic with distinct sex-based genetic differentiation. While prior studies have examined the mtDNA and Y-chromosome contrast in focal populations in the Middle East, none have undertaken a broad-spectrum survey including North and sub-Saharan Africa, Europe, and Middle Eastern populations. In this study 5,174 mtDNA and 4,658 Y-chromosome samples were investigated using PCA, MDS, mean-linkage clustering, AMOVA, and Fisher exact tests of F(ST)'s, R(ST)'s, and haplogroup frequencies. Geographic differentiation in affinities of Middle Eastern populations with Africa and Europe showed distinct contrasts between mtDNA and Y-chromosome data. Specifically, Lebanon's mtDNA shows a very strong association to Europe, while Yemen shows very strong affinity with Egypt and North and East Africa. Previous Y-chromosome results showed a Levantine coastal-inland contrast marked by J1 and J2, and a very strong North African component was evident throughout the Middle East. Neither of these patterns were observed in the mtDNA. While J2 has penetrated into Europe, the pattern of Y-chromosome diversity in Lebanon does not show the widespread affinities with Europe indicated by the mtDNA data. Lastly, while each population shows evidence of connections with expansions that now define the Middle East, Africa, and Europe, many of the populations in the Middle East show distinctive mtDNA and Y-haplogroup characteristics that indicate long standing settlement with relatively little impact from and movement into other populations.

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

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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.

A new derived and highly polymorphic chromosomal race of Liolaemus monticola (Iguanidae) from the 'Norte Chico' of Chile.

Science.gov (United States)

Lamborot, M

1998-06-01

A multiple Robertsonian fission chromosomal race of the Liolaemus monticola complex in Chile is described and is shown to be the most derived and the most complex among the Liolaemus examined thus far. The 29 karyotyped lizards analysed from the locality of Mina Hierro Viejo, Petorca, Provincia de Valparaiso, Chile, exhibited a diploid chromosomal number ranging from 42 to 44, and several polymorphisms. The polymorphisms included: a pair 1 fission; a pair 2 fission plus a pericentric inversion in one of the fission products, which moved the NOR and satellite from the tip of the long arm of the metacentric 2 to the short arm of the fission product; a fission in pair 3; a polymorphism for an enlarged chromosome pair 6; and a polymorphism for a pericentric inversion in pair 7. This population is fixed for a fission of chromosome pair 4. A total of 76% of the lizards analysed were polymorphic for one or more pairs of chromosomes. We have compared these data with other Liolaemus monticola chromosomal races and calculated the Hardy-Weinberg ratios for the polymorphic chromosome pairs in this Multiple-Fission race. Karyotypic differences between the Northern (2n = 38-40) and the Multiple-Fission (2n = 42-44) races were attributed mainly to Robertsonian fissions, an enlarged chromosome and pericentric inversions involving the macrochromosomes and one microchromosome pair.

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

The murine ufo receptor: molecular cloning, chromosomal localization and in situ expression analysis.

Science.gov (United States)

Faust, M; Ebensperger, C; Schulz, A S; Schleithoff, L; Hameister, H; Bartram, C R; Janssen, J W

1992-07-01

We have cloned the mouse homologue of the ufo oncogene. It encodes a novel tyrosine kinase receptor characterized by a unique extracellular domain containing two immunoglobulin-like and two fibronectin type III repeats. Comparison of the predicted ufo amino acid sequences of mouse and man revealed an overall identity of 87.6%. The ufo locus maps to mouse chromosome 7A3-B1 and thereby extends the known conserved linkage group between mouse chromosome 7 and human chromosome 19. RNA in situ hybridization analysis established the onset of specific ufo expression in the late embryogenesis at day 12.5 post coitum (p.c.) and localized ufo transcription to distinct substructures of a broad spectrum of developing tissues (e.g. subepidermal cells of the skin, mesenchymal cells of the periosteum). In adult animals ufo is expressed in cells forming organ capsules as well as in connective tissue structures. ufo may function as a signal transducer between specific cell types of mesodermal origin.

Fetal chromosome analysis

DEFF Research Database (Denmark)

Philip, J; Tabor, A; 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...... A + B). Pregnant women 35 years of age, women who previously had a chromosomally abnormal child, families with translocation carriers or other heritable chromosomal disease, families where the father was 50 years or more and women in families with a history of Down's syndrome (group A), were compared...... 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...

Is early-onset microsatellite and chromosomally stable colorectal cancer a hallmark of a genetic susceptibility syndrome?

Science.gov (United States)

Kets, C M; van Krieken, J H J M; van Erp, P E J; Feuth, T; Jacobs, Y H A; Brunner, H G; Ligtenberg, M J L; Hoogerbrugge, N

2008-02-15

Most colorectal cancers show either microsatellite or chromosomal instability. A subset of colorectal cancers, especially those diagnosed at young age, is known to show neither of these forms of genetic instability and thus might have a distinct pathogenesis. Colorectal cancers diagnosed at young age are suggestive for hereditary predisposition. We investigate whether such early-onset microsatellite and chromosomally stable colorectal cancers are a hallmark of a genetic susceptibility syndrome. The ploidy status of microsatellite stable (familial) colorectal cancers of patients diagnosed before age 50 (n = 127) was analyzed in relation to the histopathological characteristics and family history. As a control the ploidy status of sporadic colorectal cancer, with normal staining of mismatch repair proteins, diagnosed at the age of 69 years or above (n = 70) was determined. A diploid DNA content was used as a marker for chromosomal stability. Within the group of patients with (familial) early onset microsatellite stable colorectal cancer the chromosomally stable tumors did not differ from chromosomally unstable tumors with respect to mean age at diagnosis, fulfillment of Amsterdam criteria or pathological characteristics. Segregation analysis did not reveal any family with microsatellite and chromosomally stable colorectal cancer in 2 relatives. The prevalence of microsatellite and chromosomally stable colorectal cancer was not significantly different for the early and late onset group (28 and 21%, respectively). We find no evidence that early-onset microsatellite and chromosomally stable colorectal cancer is a hallmark of a hereditary colorectal cancer syndrome. (c) 2007 Wiley-Liss, Inc.

Microdissection and chromosome painting of the alien chromosome in an addition line of wheat-Thinopyrum intermedium

Science.gov (United States)

The chromosome painting is an efficient tool for chromosome research. However, plant chromosome painting is relatively underdeveloped. In this study, chromosome painting was developed and used to identify alien chromosomes in TAi-27, a wheat-Thinopyrum intermedium addition line, and chromosomes of...

The first sequenced carnivore genome shows complex host-endogenous retrovirus relationships.

Directory of Open Access Journals (Sweden)

Álvaro Martínez Barrio

Full Text Available Host-retrovirus interactions influence the genomic landscape and have contributed substantially to mammalian genome evolution. To gain further insights, we analyzed a female boxer (Canis familiaris genome for complexity and integration pattern of canine endogenous retroviruses (CfERV. Intriguingly, the first such in-depth analysis of a carnivore species identified 407 CfERV proviruses that represent only 0.15% of the dog genome. In comparison, the same detection criteria identified about six times more HERV proviruses in the human genome that has been estimated to contain a total of 8% retroviral DNA including solitary LTRs. These observed differences in man and dog are likely due to different mechanisms to purge, restrict and protect their genomes against retroviruses. A novel group of gammaretrovirus-like CfERV with high similarity to HERV-Fc1 was found to have potential for active retrotransposition and possibly lateral transmissions between dog and human as a result of close interactions during at least 10.000 years. The CfERV integration landscape showed a non-uniform intra- and inter-chromosomal distribution. Like in other species, different densities of ERVs were observed. Some chromosomal regions were essentially devoid of CfERVs whereas other regions had large numbers of integrations in agreement with distinct selective pressures at different loci. Most CfERVs were integrated in antisense orientation within 100 kb from annotated protein-coding genes. This integration pattern provides evidence for selection against CfERVs in sense orientation relative to chromosomal genes. In conclusion, this ERV analysis of the first carnivorous species supports the notion that different mammals interact distinctively with endogenous retroviruses and suggests that retroviral lateral transmissions between dog and human may have occurred.

Microdissection and chromosome painting of the alien chromosome in an addition line of wheat--Thinopyrum intermedium.

Science.gov (United States)

Deng, Chuanliang; Bai, Lili; Fu, Shulan; Yin, Weibo; Zhang, Yingxin; Chen, Yuhong; Wang, Richard R-C; Zhang, Xiangqi; Han, Fangpu; Hu, Zanmin

2013-01-01

In this study, chromosome painting was developed and used to identify alien chromosomes in TAi-27, a wheat--Thinopyrum intermedium addition line, and the chromosomes of the three different genomes of Th. Intermedium. The smallest alien chromosome of TAi-27 was microdissected and its DNA amplified by DOP-PCR was used as a probe to hybridize with metaphase chromosomes of TAi-27 and Th. intermedium. Results showed that hybridization signals were observed in all regions of a pair of the smallest alien chromosomes and the pericentromeric area of another pair of alien chromosomes in TAi-27, indicating that the probe from microdissected chromosome is species specific. In Th. intermedium, 14 chromosomes had wide and strong hybridization signals distributed mainly on the pericentromere area and 9 chromosomes with narrow and weak signals on the pericentromere area. The remaining chromosomes displayed a very weak or no signal. Sequential FISH/GISH on Th. intermedium chromosomes using the DNAs of microdissected chromosome, Pseudoroegneria spicata (St genome) and pDbH12 (a J(s) genome specific probe) as the probes indicated that the microdissected chromosome belonged to the St genome, three genomes (J(s) , J and St) in Th. intermedium could be distinguished, in which there is no hybridization signal on J genome that is similar to the genome of Th. bessarabicum. Our results showed that the smallest alien chromosomes may represent a truncated chromosome and the repetitive sequence distribution might be similar in different chromosomes within the St genome. However, the repetitive sequence distributions are different within the J(s) genome, within a single chromosome, and among different genomes in Th. intermedium. Our results suggested that chromosome painting could be feasible in some plants and useful in detecting chromosome variation and repetitive sequence distribution in different genomes of polyploidy plants, which is helpful for understanding the evolution of different

Microdissection and Chromosome Painting of the Alien Chromosome in an Addition Line of Wheat - Thinopyrum intermedium

Science.gov (United States)

Yin, Weibo; Zhang, Yingxin; Chen, Yuhong; Wang, Richard R.-C.; Zhang, Xiangqi; Han, Fangpu; Hu, Zanmin

2013-01-01

In this study, chromosome painting was developed and used to identify alien chromosomes in TAi-27, a wheat - Thinopyrum intermedium addition line, and the chromosomes of the three different genomes of Th. Intermedium. The smallest alien chromosome of TAi-27 was microdissected and its DNA amplified by DOP-PCR was used as a probe to hybridize with metaphase chromosomes of TAi-27 and Th . intermedium . Results showed that hybridization signals were observed in all regions of a pair of the smallest alien chromosomes and the pericentromeric area of another pair of alien chromosomes in TAi-27, indicating that the probe from microdissected chromosome is species specific. In Th . intermedium , 14 chromosomes had wide and strong hybridization signals distributed mainly on the pericentromere area and 9 chromosomes with narrow and weak signals on the pericentromere area. The remaining chromosomes displayed a very weak or no signal. Sequential FISH/GISH on Th . intermedium chromosomes using the DNAs of microdissected chromosome, Pseudoroegneria spicata (St genome) and pDbH12 (a Js genome specific probe) as the probes indicated that the microdissected chromosome belonged to the St genome, three genomes (Js, J and St) in Th . intermedium could be distinguished, in which there is no hybridization signal on J genome that is similar to the genome of Th . bessarabicum . Our results showed that the smallest alien chromosomes may represent a truncated chromosome and the repetitive sequence distribution might be similar in different chromosomes within the St genome. However, the repetitive sequence distributions are different within the Js genome, within a single chromosome, and among different genomes in Th . intermedium . Our results suggested that chromosome painting could be feasible in some plants and useful in detecting chromosome variation and repetitive sequence distribution in different genomes of polyploidy plants, which is helpful for understanding the evolution of different

Complexity analyses show two distinct types of nonlinear dynamics in short heart period variability recordings

Science.gov (United States)

Porta, Alberto; Bari, Vlasta; Marchi, Andrea; De Maria, Beatrice; Cysarz, Dirk; Van Leeuwen, Peter; Takahashi, Anielle C. M.; Catai, Aparecida M.; Gnecchi-Ruscone, Tomaso

2015-01-01

Two diverse complexity metrics quantifying time irreversibility and local prediction, in connection with a surrogate data approach, were utilized to detect nonlinear dynamics in short heart period (HP) variability series recorded in fetuses, as a function of the gestational period, and in healthy humans, as a function of the magnitude of the orthostatic challenge. The metrics indicated the presence of two distinct types of nonlinear HP dynamics characterized by diverse ranges of time scales. These findings stress the need to render more specific the analysis of nonlinear components of HP dynamics by accounting for different temporal scales. PMID:25806002

Sex chromosomes and speciation in birds and other ZW systems.

Science.gov (United States)

Irwin, Darren E

2018-02-14

Theory and empirical patterns suggest a disproportionate role for sex chromosomes in evolution and speciation. Focusing on ZW sex determination (females ZW, males ZZ; the system in birds, many snakes, and lepidopterans), I review how evolutionary dynamics are expected to differ between the Z, W and the autosomes, discuss how these differences may lead to a greater role of the sex chromosomes in speciation and use data from birds to compare relative evolutionary rates of sex chromosomes and autosomes. Neutral mutations, partially or completely recessive beneficial mutations, and deleterious mutations under many conditions are expected to accumulate faster on the Z than on autosomes. Sexually antagonistic polymorphisms are expected to arise on the Z, raising the possibility of the spread of preference alleles. The faster accumulation of many types of mutations and the potential for complex evolutionary dynamics of sexually antagonistic traits and preferences contribute to a role for the Z chromosome in speciation. A quantitative comparison among a wide variety of bird species shows that the Z tends to have less within-population diversity and greater between-species differentiation than the autosomes, likely due to both adaptive evolution and a greater rate of fixation of deleterious alleles. The W chromosome also shows strong potential to be involved in speciation, in part because of its co-inheritance with the mitochondrial genome. While theory and empirical evidence suggest a disproportionate role for sex chromosomes in speciation, the importance of sex chromosomes is moderated by their small size compared to the whole genome. © 2018 John Wiley & Sons Ltd.

Designing of plant artificial chromosome (PAC) by using the Chlorella smallest chromosome as a model system.

Science.gov (United States)

Noutoshi, Y; Arai, R; Fujie, M; Yamada, T

1997-01-01

As a model for plant-type chromosomes, we have been characterizing molecular organization of the Chlorella vulgaris C-169 chromosome I. To identify chromosome structural elements including the centromeric region and replication origins, we constructed a chromosome I specific cosmid library and aligned each cosmid clones to generate contigs. So far, more than 80% of the entire chromosome I has been covered. A complete clonal physical reconstitution of chromosome I provides information on the structure and genomic organization of plant genome. We propose our strategy to construct an artificial chromosome by assembling the functional chromosome structural elements identified on Chrorella chromosome I.

The Fanconi anemia protein FANCF forms a nuclear complex with FANCA, FANCC and FANCG.

Science.gov (United States)

de Winter, J P; van der Weel, L; de Groot, J; Stone, S; Waisfisz, Q; Arwert, F; Scheper, R J; Kruyt, F A; Hoatlin, M E; Joenje, H

2000-11-01

Fanconi anemia (FA) is a chromosomal instability syndrome associated with a strong predisposition to cancer, particularly acute myeloid leukemia and squamous cell carcinoma. At the cellular level, FA is characterized by spontaneous chromosomal breakage and a unique hypersensitivity to DNA cross-linking agents. Complementation analysis has indicated that at least seven distinct genes are involved in the pathogenesis of FA. Despite the identification of four of these genes (FANCA, FANCC, FANCF and FANCG), the nature of the 'FA pathway' has remained enigmatic, as the FA proteins lack sequence homologies or motifs that could point to a molecular function. To further define this pathway, we studied the subcellular localizations and mutual interactions of the FA proteins, including the recently identified FANCF protein, in human lymphoblasts. FANCF was found predominantly in the nucleus, where it complexes with FANCA, FANCC and FANCG. These interactions were detected in wild-type and FA-D lymphoblasts, but not in lymphoblasts of other FA complementation groups. This implies that each of the FA proteins, except FANCD, is required for these complexes to form. Similarly, we show that the interaction between FANCA and FANCC is restricted to wild-type and FA-D cells. Furthermore, we document the subcellular localization of FANCA and the FANCA/FANCG complex in all FA complementation groups. Our results, along with published data, culminate in a model in which a multi-protein FA complex serves a nuclear function to maintain genomic integrity.

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. © The American Genetic Association 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

X-Chromosome Control of Genome-Scale Recombination Rates in House Mice.

Science.gov (United States)

Dumont, Beth L

2017-04-01

Sex differences in recombination are widespread in mammals, but the causes of this pattern are poorly understood. Previously, males from two interfertile subspecies of house mice, Mus musculus musculus and M. m. castaneus , were shown to exhibit a ∼30% difference in their global crossover frequencies. Much of this crossover rate divergence is explained by six autosomal loci and a large-effect locus on the X chromosome. Intriguingly, the allelic effects at this X-linked locus are transgressive, with the allele conferring increased crossover rate being transmitted by the low crossover rate M. m. castaneus parent. Despite the pronounced divergence between males, females from these subspecies exhibit similar crossover rates, raising the question of how recombination is genetically controlled in this sex. Here, I analyze publicly available genotype data from early generations of the Collaborative Cross, an eight-way panel of recombinant inbred strains, to estimate crossover frequencies in female mice with sex-chromosome genotypes of diverse subspecific origins. Consistent with the transgressive influence of the X chromosome in males, I show that females inheriting an M. m. castaneus X possess higher average crossover rates than females lacking the M. m. castaneus X chromosome. The differential inheritance of the X chromosome in males and females provides a simple genetic explanation for sex-limited evolution of this trait. Further, the presence of X-linked and autosomal crossover rate modifiers with antagonistic effects hints at an underlying genetic conflict fueled by selection for distinct crossover rate optima in males and females. Copyright © 2017 by the Genetics Society of America.

Sex-chromosome anaphase movements in crane-fly spermatocytes are coordinated: ultraviolet microbeam irradiation of one kinetochore of one sex chromosome blocks the movements of both sex chromosomes

International Nuclear Information System (INIS)

Swedak, J.A.M.; Forer, A.

1987-01-01

Sex chromosomes in crane-fly spermatocytes move polewards at anaphase after the autosomes have reached the poles. We irradiated one kinetochore of one sex chromosome using an ultraviolet microbeam. When both sex chromosomes were normally oriented, irradiation of a single kinetochore permanently blocked movement of both sex chromosomes. Irradiation of non-kinetochore chromosomal regions or of spindle fibres did not block movement, or blocked movement only temporarily. We argue that ultraviolet irradiation of one kinetochore blocks movement of both sex chromosomes because of effects on a 'signal' system. Irradiation of one kinetochore of a maloriented sex chromosome did not block motion of either sex chromosome. However, irradiation of one kinetochore of a normally oriented sex chromosome permanently blocked motion of both that sex chromosome and the maloriented sex chromosome. Thus for the signal system to allow the sex chromosomes to move to the pole each sex chromosome must have one spindle fibre to each pole. (author)

Reassessment of genome size in turtle and crocodile based on chromosome measurement by flow karyotyping: close similarity to chicken

Science.gov (United States)

Kasai, Fumio; O'Brien, Patricia C. M.; Ferguson-Smith, Malcolm A.

2012-01-01

The genome size in turtles and crocodiles is thought to be much larger than the 1.2 Gb of the chicken (Gallus gallus domesticus, GGA), according to the animal genome size database. However, GGA macrochromosomes show extensive homology in the karyotypes of the red eared slider (Trachemys scripta elegans, TSC) and the Nile crocodile (Crocodylus niloticus, CNI), and bird and reptile genomes have been highly conserved during evolution. In this study, size and GC content of all chromosomes are measured from the flow karyotypes of GGA, TSC and CNI. Genome sizes estimated from the total chromosome size demonstrate that TSC and CNI are 1.21 Gb and 1.29 Gb, respectively. This refines previous overestimations and reveals similar genome sizes in chicken, turtle and crocodile. Analysis of chromosome GC content in each of these three species shows a higher GC content in smaller chromosomes than in larger chromosomes. This contrasts with mammals and squamates in which GC content does not correlate with chromosome size. These data suggest that a common ancestor of birds, turtles and crocodiles had a small genome size and a chromosomal size-dependent GC bias, distinct from the squamate lineage. PMID:22491763

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…

Chromosomal Conditions

Science.gov (United States)

... and more. Stony Point, NY 10980 Close X Home > Complications & Loss > Birth defects & other health conditions > Chromosomal conditions Chromosomal conditions ... Disorders See also: Genetic counseling , Your family health history Last reviewed: February, 2013 ... labor & premature birth The newborn intensive care unit (NICU) Birth defects & ...

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...

Dynamic organization of genetic recombination proteins and chromosomes

International Nuclear Information System (INIS)

Essers, J.; Van Cappellen, G.; Van Drunen, E.; Theil, A.; Jaspers, N.N.G.J.; Houtsmuller, A.B.; Vermeulen, W.; Kanaar, R.

2003-01-01

Homologous recombination requires the co-ordinated action of the RAD52 group proteins, including Rad51, Rad52 and Rad54. Upon treatment of mammalian cells with ionizing radiation, these proteins accumulate into foci at sites of DSB induction. We probed the nature of the DNA damage-induced foci in living cells with the use of photobleaching techniques. These foci are not static assemblies of DNA repair proteins. Instead, they are dynamic structures of which Rad51 is a stable core component, while Rad52 and Rad54 reversibly interact with the structure. Furthermore, even though the RAD52 group proteins colocalize in the DNA damage-induced foci, the majority of the proteins are not part of the same multi-protein complex in the absence of DNA damage. Executing DNA transactions through dynamic multi-protein complexes, rather than stable holo-complexes, allows greater flexibility during the transaction. In case of DNA repair, for example, it allows cross talk between different DNA repair pathways and coupling to other DNA transactions, such as replication. In addition to the behavior of proteins in living cells, we have tracked chromosomes during cell division. Our results suggest that the relative position of chromosomes in the mother cell is conserved in its daughter cells

Nuclear Architecture of Mouse Spermatocytes: Chromosome Topology, Heterochromatin, and Nucleolus.

Science.gov (United States)

Berrios, Soledad

2017-01-01

The nuclear organization of spermatocytes in meiotic prophase I is primarily determined by the synaptic organization of the bivalents that are bound by their telomeres to the nuclear envelope and described as arc-shaped trajectories through the 3D nuclear space. However, over this basic meiotic organization, a spermatocyte nuclear architecture arises that is based on higher-ordered patterns of spatial associations among chromosomal domains from different bivalents that are conditioned by the individual characteristics of chromosomes and the opportunity for interactions between their domains. Consequently, the nuclear architecture is species-specific and prone to modification by chromosomal rearrangements. This model is valid for the localization of any chromosomal domain in the meiotic prophase nucleus. However, constitutive heterochromatin plays a leading role in shaping nuclear territories. Thus, the nuclear localization of nucleoli depends on the position of NORs in nucleolar bivalents, but the association among nucleolar chromosomes mainly depends on the presence of constitutive heterochromatin that does not affect the expression of the ribosomal genes. Constitutive heterochromatin and nucleoli form complex nuclear territories whose distribution in the nuclear space is nonrandom, supporting the hypothesis regarding the existence of a species-specific nuclear architecture in first meiotic prophase spermatocytes. © 2017 S. Karger AG, Basel.

The 5S rDNA in two Abracris grasshoppers (Ommatolampidinae: Acrididae): molecular and chromosomal organization.

Science.gov (United States)

Bueno, Danilo; Palacios-Gimenez, Octavio Manuel; Martí, Dardo Andrea; Mariguela, Tatiane Casagrande; Cabral-de-Mello, Diogo Cavalcanti

2016-08-01

The 5S ribosomal DNA (rDNA) sequences are subject of dynamic evolution at chromosomal and molecular levels, evolving through concerted and/or birth-and-death fashion. Among grasshoppers, the chromosomal location for this sequence was established for some species, but little molecular information was obtained to infer evolutionary patterns. Here, we integrated data from chromosomal and nucleotide sequence analysis for 5S rDNA in two Abracris species aiming to identify evolutionary dynamics. For both species, two arrays were identified, a larger sequence (named type-I) that consisted of the entire 5S rDNA gene plus NTS (non-transcribed spacer) and a smaller (named type-II) with truncated 5S rDNA gene plus short NTS that was considered a pseudogene. For type-I sequences, the gene corresponding region contained the internal control region and poly-T motif and the NTS presented partial transposable elements. Between the species, nucleotide differences for type-I were noticed, while type-II was identical, suggesting pseudogenization in a common ancestor. At chromosomal point to view, the type-II was placed in one bivalent, while type-I occurred in multiple copies in distinct chromosomes. In Abracris, the evolution of 5S rDNA was apparently influenced by the chromosomal distribution of clusters (single or multiple location), resulting in a mixed mechanism integrating concerted and birth-and-death evolution depending on the unit.

Microdissection and chromosome painting of the alien chromosome in an addition line of wheat--Thinopyrum intermedium.

Directory of Open Access Journals (Sweden)

Chuanliang Deng

Full Text Available In this study, chromosome painting was developed and used to identify alien chromosomes in TAi-27, a wheat--Thinopyrum intermedium addition line, and the chromosomes of the three different genomes of Th. Intermedium. The smallest alien chromosome of TAi-27 was microdissected and its DNA amplified by DOP-PCR was used as a probe to hybridize with metaphase chromosomes of TAi-27 and Th. intermedium. Results showed that hybridization signals were observed in all regions of a pair of the smallest alien chromosomes and the pericentromeric area of another pair of alien chromosomes in TAi-27, indicating that the probe from microdissected chromosome is species specific. In Th. intermedium, 14 chromosomes had wide and strong hybridization signals distributed mainly on the pericentromere area and 9 chromosomes with narrow and weak signals on the pericentromere area. The remaining chromosomes displayed a very weak or no signal. Sequential FISH/GISH on Th. intermedium chromosomes using the DNAs of microdissected chromosome, Pseudoroegneria spicata (St genome and pDbH12 (a J(s genome specific probe as the probes indicated that the microdissected chromosome belonged to the St genome, three genomes (J(s , J and St in Th. intermedium could be distinguished, in which there is no hybridization signal on J genome that is similar to the genome of Th. bessarabicum. Our results showed that the smallest alien chromosomes may represent a truncated chromosome and the repetitive sequence distribution might be similar in different chromosomes within the St genome. However, the repetitive sequence distributions are different within the J(s genome, within a single chromosome, and among different genomes in Th. intermedium. Our results suggested that chromosome painting could be feasible in some plants and useful in detecting chromosome variation and repetitive sequence distribution in different genomes of polyploidy plants, which is helpful for understanding the evolution of

The Aurora Kinase in Trypanosoma brucei plays distinctive roles in metaphase-anaphase transition and cytokinetic initiation.

Directory of Open Access Journals (Sweden)

Ziyin Li

2009-09-01

Full Text Available Aurora B kinase is an essential regulator of chromosome segregation with the action well characterized in eukaryotes. It is also implicated in cytokinesis, but the detailed mechanism remains less clear, partly due to the difficulty in separating the latter from the former function in a growing cell. A chemical genetic approach with an inhibitor of the enzyme added to a synchronized cell population at different stages of the cell cycle would probably solve this problem. In the deeply branched parasitic protozoan Trypanosoma brucei, an Aurora B homolog, TbAUK1, was found to control both chromosome segregation and cytokinetic initiation by evidence from RNAi and dominant negative mutation. To clearly separate these two functions, VX-680, an inhibitor of TbAUK1, was added to a synchronized T. brucei procyclic cell population at different cell cycle stages. The unique trans-localization pattern of the chromosomal passenger complex (CPC, consisting of TbAUK1 and two novel proteins TbCPC1 and TbCPC2, was monitored during mitosis and cytokinesis by following the migration of the proteins tagged with enhanced yellow fluorescence protein in live cells with time-lapse video microscopy. Inhibition of TbAUK1 function in S-phase, prophase or metaphase invariably arrests the cells in the metaphase, suggesting an action of TbAUK1 in promoting metaphase-anaphase transition. TbAUK1 inhibition in anaphase does not affect mitotic exit, but prevents trans-localization of the CPC from the spindle midzone to the anterior tip of the new flagellum attachment zone for cytokinetic initiation. The CPC in the midzone is dispersed back to the two segregated nuclei, while cytokinesis is inhibited. In and beyond telophase, TbAUK1 inhibition has no effect on the progression of cytokinesis or the subsequent G1, S and G2 phases until a new metaphase is attained. There are thus two clearly distinct points of TbAUK1 action in T. brucei: the metaphase-anaphase transition and

Pure chromosome-specific PCR libraries from single sorted chromosomes

NARCIS (Netherlands)

VanDevanter, D. R.; Choongkittaworn, N. M.; Dyer, K. A.; Aten, J. A.; Otto, P.; Behler, C.; Bryant, E. M.; Rabinovitch, P. S.

1994-01-01

Chromosome-specific DNA libraries can be very useful in molecular and cytogenetic genome mapping studies. We have developed a rapid and simple method for the generation of chromosome-specific DNA sequences that relies on polymerase chain reaction (PCR) amplification of a single flow-sorted

Mechanisms of telomere loss and their consequences for chromosome instability

International Nuclear Information System (INIS)

Muraki, Keiko; Nyhan, Kristine; Han, Limei; Murnane, John P.

2012-01-01

The ends of chromosomes in mammals, called telomeres, are composed of a 6-bp repeat sequence, TTAGGG, which is added on by the enzyme telomerase. In combination with a protein complex called shelterin, these telomeric repeat sequences form a cap that protects the ends of chromosomes. Due to insufficient telomerase expression, telomeres shorten gradually with each cell division in human somatic cells, which limits the number of times they can divide. The extensive cell division involved in cancer cell progression therefore requires that cancer cells must acquire the ability to maintain telomeres, either through expression of telomerase, or through an alternative mechanism involving recombination. It is commonly thought that the source of many chromosome rearrangements in cancer cells is a result of the extensive telomere shortening that occurs prior to the expression of telomerase. However, despite the expression of telomerase, tumor cells can continue to show chromosome instability due to telomere loss. Dysfunctional telomeres in cancer cells can result from oncogene-induced replication stress, which results in double-strand breaks (DSBs) at fragile sites, including telomeres. DSBs near telomeres are especially prone to chromosome rearrangements, because telomeric regions are deficient in DSB repair. The deficiency in DSB repair near telomeres is also an important mechanism for ionizing radiation-induced replicative senescence in normal human cells. In addition, DSBs near telomeres can result in chromosome instability in mouse embryonic stem cells, suggesting that telomere loss can contribute to heritable chromosome rearrangements. Consistent with this possibility, telomeric regions in humans are highly heterogeneous, and chromosome rearrangements near telomeres are commonly involved in human genetic disease. Understanding the mechanisms of telomere loss will therefore provide important insights into both human cancer and genetic disease.

Mechanisms of telomere loss and their consequences for chromosome instability

Directory of Open Access Journals (Sweden)

Keiko eMuraki

2012-10-01

Full Text Available The ends of chromosomes in mammals, called telomeres, are composed of a 6 base pair repeat sequence, TTAGGG, which is added on by the enzyme telomerase. In combination with a protein complex called shelterin, these telomeric repeat sequences form a cap that protects the ends of chromosomes. Due to insufficient telomerase expression, telomeres shorten gradually with each cell division in human somatic cells, which limits the number of times they can divide. The extensive cell division involved in cancer cell progression therefore requires that cancer cells must acquire the ability to maintain telomeres, either through expression of telomerase, or through an alternative mechanism involving recombination. It is commonly thought that the source of many chromosome rearrangements in cancer cells is a result of the extensive telomere shortening that occurs prior to the expression of telomerase. However, despite the expression of telomerase, tumor cells can continue to show chromosome instability due to telomere loss. Dysfunctional telomeres in cancer cells can result from oncogene-induced replication stress, which results in double-strand breaks (DSBs at fragile sites, including telomeres. DSBs near telomeres are especially prone to chromosome rearrangements, because telomeric regions are deficient in DSB repair. The deficiency in DSB repair near telomeres is also an important mechanism for ionizing radiation-induced replicative senescence in normal human cells. In addition, DSBs near telomeres can result in chromosome instability in mouse embryonic stem cells, suggesting that telomere loss can contribute to heritable chromosome rearrangements. Consistent with this possibility, telomeric regions in humans are highly heterogeneous, and chromosome rearrangements near telomeres are commonly involved in human genetic disease. Understanding the mechanisms of telomere loss will therefore provide important insights into both human cancer and genetic disease.

Mechanisms of telomere loss and their consequences for chromosome instability

Energy Technology Data Exchange (ETDEWEB)

Muraki, Keiko; Nyhan, Kristine; Han, Limei; Murnane, John P., E-mail: jmurnane@radonc.ucsf.edu [Department of Radiation Oncology, University of California at San Francisco, San Francisco, CA (United States)

2012-10-04

The ends of chromosomes in mammals, called telomeres, are composed of a 6-bp repeat sequence, TTAGGG, which is added on by the enzyme telomerase. In combination with a protein complex called shelterin, these telomeric repeat sequences form a cap that protects the ends of chromosomes. Due to insufficient telomerase expression, telomeres shorten gradually with each cell division in human somatic cells, which limits the number of times they can divide. The extensive cell division involved in cancer cell progression therefore requires that cancer cells must acquire the ability to maintain telomeres, either through expression of telomerase, or through an alternative mechanism involving recombination. It is commonly thought that the source of many chromosome rearrangements in cancer cells is a result of the extensive telomere shortening that occurs prior to the expression of telomerase. However, despite the expression of telomerase, tumor cells can continue to show chromosome instability due to telomere loss. Dysfunctional telomeres in cancer cells can result from oncogene-induced replication stress, which results in double-strand breaks (DSBs) at fragile sites, including telomeres. DSBs near telomeres are especially prone to chromosome rearrangements, because telomeric regions are deficient in DSB repair. The deficiency in DSB repair near telomeres is also an important mechanism for ionizing radiation-induced replicative senescence in normal human cells. In addition, DSBs near telomeres can result in chromosome instability in mouse embryonic stem cells, suggesting that telomere loss can contribute to heritable chromosome rearrangements. Consistent with this possibility, telomeric regions in humans are highly heterogeneous, and chromosome rearrangements near telomeres are commonly involved in human genetic disease. Understanding the mechanisms of telomere loss will therefore provide important insights into both human cancer and genetic disease.

Y-Chromosomal Diversity in Europe Is Clinal and Influenced Primarily by Geography, Rather than by Language

Science.gov (United States)

Rosser, Zoë H.; Zerjal, Tatiana; Hurles, Matthew E.; Adojaan, Maarja; Alavantic, Dragan; Amorim, António; Amos, William; Armenteros, Manuel; Arroyo, Eduardo; Barbujani, Guido; Beckman, Gunhild; Beckman, Lars; Bertranpetit, Jaume; Bosch, Elena; Bradley, Daniel G.; Brede, Gaute; Cooper, Gillian; Côrte-Real, Helena B. S. M.; de Knijff, Peter; Decorte, Ronny; Dubrova, Yuri E.; Evgrafov, Oleg; Gilissen, Anja; Glisic, Sanja; Gölge, Mukaddes; Hill, Emmeline W.; Jeziorowska, Anna; Kalaydjieva, Luba; Kayser, Manfred; Kivisild, Toomas; Kravchenko, Sergey A.; Krumina, Astrida; Kučinskas, Vaidutis; Lavinha, João; Livshits, Ludmila A.; Malaspina, Patrizia; Maria, Syrrou; McElreavey, Ken; Meitinger, Thomas A.; Mikelsaar, Aavo-Valdur; Mitchell, R. John; Nafa, Khedoudja; Nicholson, Jayne; Nørby, Søren; Pandya, Arpita; Parik, Jüri; Patsalis, Philippos C.; Pereira, Luísa; Peterlin, Borut; Pielberg, Gerli; Prata, Maria João; Previderé, Carlo; Roewer, Lutz; Rootsi, Siiri; Rubinsztein, D. C.; Saillard, Juliette; Santos, Fabrício R.; Stefanescu, Gheorghe; Sykes, Bryan C.; Tolun, Aslihan; Villems, Richard; Tyler-Smith, Chris; Jobling, Mark A.

2000-01-01

Clinal patterns of autosomal genetic diversity within Europe have been interpreted in previous studies in terms of a Neolithic demic diffusion model for the spread of agriculture; in contrast, studies using mtDNA have traced many founding lineages to the Paleolithic and have not shown strongly clinal variation. We have used 11 human Y-chromosomal biallelic polymorphisms, defining 10 haplogroups, to analyze a sample of 3,616 Y chromosomes belonging to 47 European and circum-European populations. Patterns of geographic differentiation are highly nonrandom, and, when they are assessed using spatial autocorrelation analysis, they show significant clines for five of six haplogroups analyzed. Clines for two haplogroups, representing 45% of the chromosomes, are continentwide and consistent with the demic diffusion hypothesis. Clines for three other haplogroups each have different foci and are more regionally restricted and are likely to reflect distinct population movements, including one from north of the Black Sea. Principal-components analysis suggests that populations are related primarily on the basis of geography, rather than on the basis of linguistic affinity. This is confirmed in Mantel tests, which show a strong and highly significant partial correlation between genetics and geography but a low, nonsignificant partial correlation between genetics and language. Genetic-barrier analysis also indicates the primacy of geography in the shaping of patterns of variation. These patterns retain a strong signal of expansion from the Near East but also suggest that the demographic history of Europe has been complex and influenced by other major population movements, as well as by linguistic and geographic heterogeneities and the effects of drift. PMID:11078479

Chromosomal homologies among vampire bats revealed by chromosome painting (phyllostomidae, chiroptera).

Science.gov (United States)

Sotero-Caio, C G; Pieczarka, J C; Nagamachi, C Y; Gomes, A J B; Lira, T C; O'Brien, P C M; Ferguson-Smith, M A; Souza, M J; Santos, N

2011-01-01

Substantial effort has been made to elucidate karyotypic evolution of phyllostomid bats, mostly through comparisons of G-banding patterns. However, due to the limited number of G-bands in respective karyotypes and to the similarity of non-homologous bands, an accurate evolutionary history of chromosome segments remains questionable. This is the case for vampire bats (Desmodontinae). Despite several proposed homologies, banding data have not yet provided a detailed understanding of the chromosomal changes within vampire genera. We examined karyotype differentiation of the 3 species within this subfamily using whole chromosomal probes from Phyllostomus hastatus (Phyllostominae) and Carollia brevicauda (Carolliinae). Painting probes of P. hastatus respectively detected 22, 21 and 23 conserved segments in Diphylla ecaudata, Diaemus youngi, and Desmodus rotundus karyotypes, whereas 27, 27 and 28 were respectively detectedwith C. brevicauda paints. Based on the evolutionary relationships proposed by morphological and molecular data, we present probable chromosomal synapomorphies for vampire bats and propose chromosomes that were present in the common ancestor of the 5 genera analyzed. Karyotype comparisons allowed us to relate a number of conserved chromosomal segments among the 5 species, providing a broader database for understanding karyotype evolution in the family. 2010 S. Karger AG, Basel.

Cytogeography and chromosome evolution of subgenus Tridentatae of Artemisia (Asteraceae)

Science.gov (United States)

E. Durant McArthur; Stewart C. Sanderson

1999-01-01

The subgenus Tridentatae of Artemisia (Asteraceae: Anthemideae) is composed of 11 species of various taxonomic and geographic complexities. It is centered on Artemisia tridentata with its three widespread common subspecies and two more geographically confined ones. Meiotic chromosome counts on pollen mother cells...

Human artificial chromosomes with alpha satellite-based de novo centromeres show increased frequency of nondisjunction and anaphase lag.

Science.gov (United States)

Rudd, M Katharine; Mays, Robert W; Schwartz, Stuart; Willard, Huntington F

2003-11-01

Human artificial chromosomes have been used to model requirements for human chromosome segregation and to explore the nature of sequences competent for centromere function. Normal human centromeres require specialized chromatin that consists of alpha satellite DNA complexed with epigenetically modified histones and centromere-specific proteins. While several types of alpha satellite DNA have been used to assemble de novo centromeres in artificial chromosome assays, the extent to which they fully recapitulate normal centromere function has not been explored. Here, we have used two kinds of alpha satellite DNA, DXZ1 (from the X chromosome) and D17Z1 (from chromosome 17), to generate human artificial chromosomes. Although artificial chromosomes are mitotically stable over many months in culture, when we examined their segregation in individual cell divisions using an anaphase assay, artificial chromosomes exhibited more segregation errors than natural human chromosomes (P artificial chromosomes missegregate over a fivefold range, the data suggest that variable centromeric DNA content and/or epigenetic assembly can influence the mitotic behavior of artificial chromosomes.

New Y chromosomes and early stages of sex chromosome ...

Indian Academy of Sciences (India)

2010-09-06

Sep 6, 2010 ... chromosomes are evolutionary consequences of that func- tion. Given sufficient ... (for a review, see Charlesworth et al. 2005). ... In the present paper, I review sex deter- mination .... part had apparently been exchanged against the homologous ... age group III-Y chromosomes were successful while in well-.

Using 3-color chromosome painting to decide between chromosome aberration models

International Nuclear Information System (INIS)

Lucas, J.N.; Sachs, R.K.

1993-01-01

Ionizing radiation produces chromosome aberrations when DNA double strand breaks (DSB) interact pairwise. For more than 30 years there have been two main, competing theories of such binary DSB interactions. The classical theory asserts that an unrepaired DSB makes two ends which separate, with each end subsequently able to join any similar (non-telomeric) end. The exchange theory asserts that the two DSB ends remain associated until repair or a reciprocal chromosome exchange involving a second DSB occurs. The authors conducted an experiment to test these models, using 3-color chromosome painting. After in vitro irradiation of resting human lymphocytes, they observed cells with three-color triplets at first metaphase: three derivative chromosomes having permuted colors, as if three broken chromosomes had played musical chairs. On the exchange model in its standard form such 3-color triplets cannot occur. On the classical model the expected frequency can be calculated. They report data and computer calculations which exclude the exchange model and favor the classical model

Human Artificial Chromosomes with Alpha Satellite-Based De Novo Centromeres Show Increased Frequency of Nondisjunction and Anaphase Lag

OpenAIRE

Rudd, M. Katharine; Mays, Robert W.; Schwartz, Stuart; Willard, Huntington F.

2003-01-01

Human artificial chromosomes have been used to model requirements for human chromosome segregation and to explore the nature of sequences competent for centromere function. Normal human centromeres require specialized chromatin that consists of alpha satellite DNA complexed with epigenetically modified histones and centromere-specific proteins. While several types of alpha satellite DNA have been used to assemble de novo centromeres in artificial chromosome assays, the extent to which they fu...

Persistence of chromosomal abnormalities additional to the Philadelphia chromosome after Philadelphia chromosome disappearance during imatinib therapy for chronic myeloid leukemia.

Science.gov (United States)

Zaccaria, Alfonso; Valenti, Anna Maria; Donti, Emilio; Gozzetti, Alessandro; Ronconi, Sonia; Spedicato, Francesco

2007-04-01

Five Philadelphia chromosome positive (Ph+) chronic myeloid leukemia (CML) patients with additional chromosome abnormalities at diagnosis have been followed during Imatinib therapy. In all, the Ph chromosome disappeared, while the 5 cases, additional abnormalities [dup(1); del(5), +8 (2 patients) and +14] persisted in the subsequent studies, performed over a period of 11 to 49 months, either alone or together with a karyotypically normal cell population. This finding is consistent with a secondary origin of the Ph chromosome in these patients. It is still to early to evaluate the possible prognostic value of these additional abnormalities.

Chromosomal instability and double minute chromosomes in a breast cancer patient

International Nuclear Information System (INIS)

Lalic, H.; Radosevic-Stasic, B.

2004-01-01

Cytogenetic analysis was performed in peripheral blood lymphocytes (PBL) of a woman with ductal breast carcinoma, who as a hospital employee was exposed professionally for 15 years to low doses of ionizing radiation. The most important finding after the chemotherapy in combination with radiotherapy was the presence of double minutes (DM) chromosomes, in combination with other chromosomal abnormalities (on 200 scored metaphases were found 2 chromatid breaks, 10 dicentrics, 11 acentric fragments, 2 gaps, and 3 double min chromosomes). In a repeated analysis (after 6 months), DM chromosomes were still present. To rule out the possibility that the patient was overexposed to ionizing radiation at work, her blood test was compared with a group of coworkers as well as with a group of professionally unexposed people. The data rejected this possibility, but the retroactive analysis showed that the patient even at the time of employment had a moderately increased number of chromosomal aberrations (3.5%) consisting of 3 isochromatids and 4 gaps, suggesting that her initial genomic instability enhanced the later development. The finding of a continuous presence of rare DM chromosomes in her PBL (4 and 10 months after radio-chemotherapy) was considered as an indicator of additional risk, which might have some prognostic significance. (author)

Distinct white matter integrity in glutamic acid decarboxylase and voltage-gated potassium channel-complex antibody-associated limbic encephalitis.

Science.gov (United States)

Wagner, Jan; Schoene-Bake, Jan-Christoph; Witt, Juri-Alexander; Helmstaedter, Christoph; Malter, Michael P; Stoecker, Winfried; Probst, Christian; Weber, Bernd; Elger, Christian E

2016-03-01

Autoantibodies against glutamic acid decarboxylase (GAD) and the voltage-gated potassium channel (VGKC) complex are associated with distinct subtypes of limbic encephalitis regarding clinical presentation, response to therapy, and outcome. The aim of this study was to investigate white matter changes in these two limbic encephalitis subtypes by means of diffusion tensor imaging (DTI). Diffusion data were obtained in 14 patients with GAD antibodies and 16 patients with VGKC-complex antibodies and compared with age- and gender-matched control groups. Voxelwise statistical analysis was carried out using tract-based spatial statistics. The results were furthermore compared with those of 15 patients with unilateral histologically confirmed hippocampal sclerosis and correlated with verbal and figural memory performance. We found widespread changes of fractional anisotropy and all diffusivity parameters in GAD-associated limbic encephalitis, whereas no changes were found in VGKC-complex-associated limbic encephalitis. The changes observed in the GAD group were even more extensive when compared against those of the hippocampal sclerosis group, although the disease duration was markedly shorter in patients with GAD antibodies. Correlation analysis revealed areas with a trend toward a negative correlation of diffusivity parameters with figural memory performance located mainly in the right temporal lobe in the GAD group as well. The present study provides further evidence that, depending on the associated antibody, limbic encephalitis features clearly distinct imaging characteristics by showing widespread white matter changes in GAD-associated limbic encephalitis and preserved white matter integrity in VGKC-complex-associated limbic encephalitis. Furthermore, our results contribute to a better understanding of the specific pathophysiologic properties in these two subforms of limbic encephalitis by revealing that patients with GAD antibodies show widespread affections of

Complex posttraumatic stress disorder: The need to consolidate a distinct clinical syndrome or to reevaluate features of psychiatric disorders following interpersonal trauma?

Science.gov (United States)

Giourou, Evangelia; Skokou, Maria; Andrew, Stuart P; Alexopoulou, Konstantina; Gourzis, Philippos; Jelastopulu, Eleni

2018-03-22

Complex posttraumatic stress disorder (Complex PTSD) has been recently proposed as a distinct clinical entity in the WHO International Classification of Diseases, 11 th version, due to be published, two decades after its first initiation. It is described as an enhanced version of the current definition of PTSD, with clinical features of PTSD plus three additional clusters of symptoms namely emotional dysregulation, negative self-cognitions and interpersonal hardship, thus resembling the clinical features commonly encountered in borderline personality disorder (BPD). Complex PTSD is related to complex trauma which is defined by its threatening and entrapping context, generally interpersonal in nature. In this manuscript, we review the current findings related to traumatic events predisposing the above-mentioned disorders as well as the biological correlates surrounding them, along with their clinical features. Furthermore, we suggest that besides the present distinct clinical diagnoses (PTSD; Complex PTSD; BPD), there is a cluster of these comorbid disorders, that follow a continuum of trauma and biological severity on a spectrum of common or similar clinical features and should be treated as such. More studies are needed to confirm or reject this hypothesis, particularly in clinical terms and how they correlate to clinical entities' biological background, endorsing a shift from the phenomenologically only classification of psychiatric disorders towards a more biologically validated classification.

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

Noninvolvement of the X chromosome in radiation-induced chromosome translocations in the human lymphoblastoid cell line TK6

International Nuclear Information System (INIS)

Jordan, R.; Schwartz, J.L.

1994-01-01

Fluorescence in situ hybridization procedures were used to examine the influence of chromosome locus on the frequency and type of chromosome aberrations induced by 60 Co γ rays in the human lymphoblastoid cell line TK6. Aberrations involving the X chromosome were compared to those involving the similarly sized autosome chromosome 7. When corrected for DNA content, acentric fragments were induced with equal frequency in the X and 7 chromosomes. Dose-dependent increases in chromosomal interchanges involving chromosome 7 were noted, and the frequencies of balanced translocations and dicentrics produced were approximately equal. Chromosome interchanges involving the X chromosome were rare and showed no apparent dose dependence. Thus, while chromosomes 7 and X are equally sensitive to the induction of chromosome breaks, the X chromosome is much less likely to interact with autosomes than chromosome 7. The noninvolvement of the X chromosome in translocations with autosomes may reflect a more peripheral and separate location for the X chromosome in the mammalian nucleus. 20 refs., 2 figs., 1 tab

Students Fail to Transfer Knowledge of Chromosome Structure to Topics Pertaining to Cell Division

Science.gov (United States)

Newman, Dina L.; Catavero, Christina M.; Wright, L. Kate

2012-01-01

Cellular processes that rely on knowledge of molecular behavior are difficult for students to comprehend. For example, thorough understanding of meiosis requires students to integrate several complex concepts related to chromosome structure and function. Using a grounded theory approach, we have unified classroom observations, assessment data, and in-depth interviews under the theory of knowledge transfer to explain student difficulties with concepts related to chromosomal behavior. In this paper, we show that students typically understand basic chromosome structure but do not activate cognitive resources that would allow them to explain macromolecular phenomena (e.g., homologous pairing during meiosis). To improve understanding of topics related to genetic information flow, we suggest that instructors use pedagogies and activities that prime students for making connections between chromosome structure and cellular processes. PMID:23222838

Entropic effects in formation of chromosome territories: towards understanding of radiation-induced gene translocation frequency

Science.gov (United States)

Gudowska-Nowak, Ewa; Ritter, Sylvia; Durante, Marco; Deperas-Standylo, Joanna; Ciesla, Michal

2012-07-01

A detailed understanding of structural organization of biological target, such as geometry of an inter-phase chromosome, is an essential prerequisite for gaining deeper insight into relationship between radiation track structure and radiation-induced biological damage [1]. In particular, coupling of biophysical models aimed to describe architecture of chromosomes and their positioning in a cell nucleus [2-4] with models of local distribution of ionizations caused by passing projectiles, are expected to result in more accurate estimates of aberration induction caused by radiation. There is abundant experimental evidence indicating that arrangements of chromosomes in eukaryotic cell nucleus is non-random and has been evolutionary conserved in specific cell types. Moreover, the radial position of a given chromosome territory (CT) within the cell nucleus has been shown to correlate with its size and gene density. Usually it is assumed that chromosomal geometry and positioning result from the action of specific forces acting locally, such as hydrogen bonds, electrostatic, Van der Waals or hydrophobic interactions operating between nucleosomes and within their interiors. However, it is both desirable and instructive to learn to what extend organization of inter-phase chromosomes is affected by nonspecific entropic forces. In this study we report results of a coarse-grained analysis of a chromatin structure modeled by two distinct approaches. In the first method, we adhere to purely statistical analysis of chromatin packing within a chromosome territory. On the basis of the polymer theory, the chromatin fiber of diameter 30nm is approximated by a chain of spheres, each corresponding to about 30 kbp. Random positioning of the center of the domain is repeated for 1000 spherical nuclei. Configuration of the domain is determined by a random packing of a polymer (a string of identical beads) in estimated fraction of space occupied by a chromosome of a given length and mass

Chromosome painting in biological dosimetry: Semi-automatic system to score stable chromosome aberrations

International Nuclear Information System (INIS)

Garcia-Sagredo, J.M.; Vallcorba, I.; Sanchez-Hombre, M.C.; Ferro, M.T.; San Roman Cos-Gayon, C.; Santos, A.; Malpica, N.; Ortiz, C.

1997-01-01

From the beginning of the description of the procedure of chromosome painting by fluorescence in situ hybridization (FISH), it was thought its possible application to score induced chromosomal aberrations in radiation exposition. With chromosome painting it is possible to detect changes between chromosomes that has been validated in radiation exposition. Translocation scoring by FISH, contrarily to the unstable dicentrics, mainly detect stable chromosome aberrations that do not disappear, it allows the capability of quantify delayed acute expositions or chronic cumulative expositions. The large number of cells that have to be analyzed for high accuracy, specially when dealing with low radiation doses, makes it almost imperative to use an automatic analysis system. After validate translocation scoring by FISH in our, we have evaluated the ability and sensitivity to detect chromosomal aberrations by chromosome using different paint probes used, showing that any combination of paint probes can be used to score induced chromosomal aberrations. Our group has developed a FISH analysis that is currently being adapted for translocation scoring analysis. It includes systematic error correction and internal control probes. The performance tests carried out show that 9,000 cells can be analyzed in 10 hr. using a Sparc 4/370. Although with a faster computer, a higher throughput is expected, for large population screening or very low radiation doses, this performance still has to be improved. (author)

Molecular diagnostic testing for Klinefelter syndrome and other male sex chromosome aneuploidies

Directory of Open Access Journals (Sweden)

Hager Karl

2012-04-01

Full Text Available Abstract Background Male sex chromosome aneuploidies are underdiagnosed despite concomitant physical and behavioral manifestations. Objective To develop a non-invasive, rapid and high-throughput molecular diagnostic assay for detection of male sex chromosome aneuploidies, including 47,XXY (Klinefelter, 47,XYY, 48,XXYY and 48,XXXY syndromes. Methods The assay utilizes three XYM and four XA markers to interrogate Y:X and X:autosome ratios, respectively. The seven markers were PCR amplified using genomic DNA isolated from a cohort of 323 males with aneuploid (n = 117 and 46,XY (n = 206 karyotypes. The resulting PCR products were subjected to Pyrosequencing, a quantitative DNA sequencing method. Results Receiver operator characteristic (ROC curves were used to establish thresholds for the discrimination of aneuploid from normal samples. The XYM markers permitted the identification of 47,XXY, 48,XXXY and 47,XYY syndromes with 100% sensitivity and specificity in both purified DNA and buccal swab samples. The 48,XXYY karyotype was delineated by XA marker data from 46,XY; an X allele threshold of 43% also permitted detection of 48,XXYY with 100% sensitivity and specificity. Analysis of X chromosome-specific biallelic SNPs demonstrated that 43 of 45 individuals (96% with 48,XXYY karyotype had two distinct X chromosomes, while 2 (4% had a duplicate X, providing evidence that 48,XXYY may result from nondisjunction during early mitotic divisions of a 46,XY embryo. Conclusions Quantitative Pyrosequencing, with high-throughput potential, can detect male sex chromosome aneuploidies with 100% sensitivity.

Revisiting Meiosis in Sugarcane: Chromosomal Irregularities and the Prevalence of Bivalent Configurations

Directory of Open Access Journals (Sweden)

Maria Lucia C. Vieira

2018-06-01

Full Text Available Traditional sugarcane cultivars (Saccharum officinarum proved highly susceptible to diseases, and this led breeders to progress to interspecific crosses resulting in disease resistance. A backcrossing program to S. officinarum was then required to boost sucrose content. Clonal selection across generations and incorporation of other germplasm into cultivated backgrounds established the (narrow genetic base of modern cultivars (Saccharum spp., which have a man-made genome. The genome complexity has inspired several molecular studies that have elucidated aspects of sugarcane genome constitution, architecture, and cytogenetics. However, there is a critical shortage of information on chromosome behavior throughout meiosis in modern cultivars. In this study, we examined the microsporogenesis of a contemporary variety, providing a detailed analysis of the meiotic process and chromosome association at diakinesis, using FISH with centromeric probes. Chromosomal abnormalities were documented by examining high quality preparations of pollen mother cells (700 in total. Approximately 70% of the cells showed abnormalities, such as metaphase chromosomes not lined up at the plate, lagging chromosomes and chromosomal bridges, and tetrad cells with micronuclei. Some dyads with asynchronous behavior were also observed. Due to the hybrid composition of the sugarcane genome, we suggest that bivalent incomplete pairing may occur in the first prophase leading to univalency. The presence of rod bivalents showing the lagging tendency is consistent with a reduction in chiasma frequency. Finally, the presence of chromatin bridges indicates the indirect occurrence of chromosomal inversions, although chromosome fragments were not clearly recognized. Possible reasons for such meiotic abnormalities and the large prevalence of bivalent formation are discussed.

Appearance and evolution of the specific chromosomal rearrangements associated with malignant transformation of mouse m5S cells

International Nuclear Information System (INIS)

Kodama, S.; Okumura, Y.; Komatsu, K.; Sasaki, M.S.

1991-01-01

Chromosomal alterations were studied during the acquisition of malignant phenotypes in two karyotypically distinct cells isolated from transformed foci induced by x-irradiation in mouse m5S cells. Because the transformants, despite foci origin, showed low ability to grow in agar, they were cultured in vitro with serial transfer schedules to allow further cell generations and assayed for anchorage independence (AI) at each passage level. The AI frequency increased with the cell doubling numbers. Chromosome analysis showed that a focus was one cell origin, but the transformants showed karyotypic instability during cell proliferation, giving rise to the rearrangements clustered in the distal region of the specific chromosomes. These rearrangements appeared to be directed toward the acquisition of malignant phenotypes. Analysis of the types and sites of rearrangements indicated that a mechanism exists that induces frequent rearrangements of the specific region of a chromosome during the process of transformation into the malignant state

Drug-induced premature chromosome condensation (PCC) protocols: cytogenetic approaches in mitotic chromosome and interphase chromatin.

Science.gov (United States)

Gotoh, Eisuke

2015-01-01

Chromosome analysis is a fundamental technique which is used in wide areas of cytogenetic study including karyotyping species, hereditary diseases diagnosis, or chromosome biology study. Chromosomes are usually prepared from mitotic cells arrested by colcemid block protocol. However, obtaining mitotic chromosomes is often hampered under several circumstances. As a result, cytogenetic analysis will be sometimes difficult or even impossible in such cases. Premature chromosome condensation (PCC) (see Note 1) is an alternative method that has proved to be a unique and useful way in chromosome analysis. Former, PCC has been achieved following cell fusion method (cell-fusion PCC) mediated either by fusogenic viruses (e.g., Sendai virus) or cell fusion chemicals (e.g., polyethylene glycol), but the cell fusion PCC has several drawbacks. The novel drug-induced PCC using protein phosphatase inhibitors was introduced about 20 years ago. This method is much simpler and easier even than the conventional mitotic chromosome preparation protocol use with colcemid block and furthermore obtained PCC index (equivalent to mitotic index for metaphase chromosome) is usually much higher than colcemid block method. Moreover, this method allows the interphase chromatin to be condensed to visualize like mitotic chromosomes. Therefore drug-induced PCC has opened the way for chromosome analysis not only in metaphase chromosomes but also in interphase chromatin. The drug-induced PCC has thus proven the usefulness in cytogenetics and other cell biology fields. For this second edition version, updated modifications/changes are supplemented in Subheadings 2, 3, and 4, and a new section describing the application of PCC in chromosome science fields is added with citation of updated references.

Arabidopsis PCH2 Mediates Meiotic Chromosome Remodeling and Maturation of Crossovers.

Directory of Open Access Journals (Sweden)

Christophe Lambing

2015-07-01

Full Text Available Meiotic chromosomes are organized into linear looped chromatin arrays by a protein axis localized along the loop-bases. Programmed remodelling of the axis occurs during prophase I of meiosis. Structured illumination microscopy (SIM has revealed dynamic changes in the chromosome axis in Arabidopsis thaliana and Brassica oleracea. We show that the axis associated protein ASY1 is depleted during zygotene concomitant with synaptonemal complex (SC formation. Study of an Atpch2 mutant demonstrates this requires the conserved AAA+ ATPase, PCH2, which localizes to the sites of axis remodelling. Loss of PCH2 leads to a failure to deplete ASY1 from the axes and compromizes SC polymerisation. Immunolocalization of recombination proteins in Atpch2 indicates that recombination initiation and CO designation during early prophase I occur normally. Evidence suggests that CO interference is initially functional in the mutant but there is a defect in CO maturation following designation. This leads to a reduction in COs and a failure to form COs between some homologous chromosome pairs leading to univalent chromosomes at metaphase I. Genetic analysis reveals that CO distribution is also affected in some chromosome regions. Together these data indicate that the axis remodelling defect in Atpch2 disrupts normal patterned formation of COs.

APC/C Dysfunction Limits Excessive Cancer Chromosomal Instability.

Science.gov (United States)

Sansregret, Laurent; Patterson, James O; Dewhurst, Sally; López-García, Carlos; Koch, André; McGranahan, Nicholas; Chao, William Chong Hang; Barry, David J; Rowan, Andrew; Instrell, Rachael; Horswell, Stuart; Way, Michael; Howell, Michael; Singleton, Martin R; Medema, René H; Nurse, Paul; Petronczki, Mark; Swanton, Charles

2017-02-01

Intercellular heterogeneity, exacerbated by chromosomal instability (CIN), fosters tumor heterogeneity and drug resistance. However, extreme CIN correlates with improved cancer outcome, suggesting that karyotypic diversity required to adapt to selection pressures might be balanced in tumors against the risk of excessive instability. Here, we used a functional genomics screen, genome editing, and pharmacologic approaches to identify CIN-survival factors in diploid cells. We find partial anaphase-promoting complex/cyclosome (APC/C) dysfunction lengthens mitosis, suppresses pharmacologically induced chromosome segregation errors, and reduces naturally occurring lagging chromosomes in cancer cell lines or following tetraploidization. APC/C impairment caused adaptation to MPS1 inhibitors, revealing a likely resistance mechanism to therapies targeting the spindle assembly checkpoint. Finally, CRISPR-mediated introduction of cancer somatic mutations in the APC/C subunit cancer driver gene CDC27 reduces chromosome segregation errors, whereas reversal of an APC/C subunit nonsense mutation increases CIN. Subtle variations in mitotic duration, determined by APC/C activity, influence the extent of CIN, allowing cancer cells to dynamically optimize fitness during tumor evolution. We report a mechanism whereby cancers balance the evolutionary advantages associated with CIN against the fitness costs caused by excessive genome instability, providing insight into the consequence of CDC27 APC/C subunit driver mutations in cancer. Lengthening of mitosis through APC/C modulation may be a common mechanism of resistance to cancer therapeutics that increase chromosome segregation errors. Cancer Discov; 7(2); 218-33. ©2017 AACR.See related commentary by Burkard and Weaver, p. 134This article is highlighted in the In This Issue feature, p. 115. ©2017 American Association for Cancer Research.

A Newborn with Genital Ambiguity, 45,X/46,XY Mosaicism, a Jumping Chromosome Y, and Congenital Adrenal Hyperplasia

Directory of Open Access Journals (Sweden)

Lei Zhang

2013-01-01

Full Text Available Disorders of sex development (DSD, formerly termed “intersex” conditions, arise from numerous causes. CAH secondary to 21-hydroxylase deficiency is the most common cause of DSD. Sex chromosome disorders, including sex chromosome mosaicism, are the second most common cause of DSD. We discuss a medically complex neonate with DSD presenting with ambiguous genitalia. Hormone levels suggested 21-hydroxylase deficiency. Molecular analysis revealed compound heterozygous mutations in the 21-hydroxylase gene (CYP21A2, confirming the diagnosis of CAH. Chromosome analysis revealed sex chromosome mosaicism with three cell lines: 45,X[8]/45,X,tas(Y;16(p11.32;p13.3[8]/45,X,t(Y;8(p11.32;p23.3[4] with the Y chromosome in telomere association with chromosomes 8p and 16p in different cell lines, a “jumping translocation.” Histologically, the right gonad had irregular, distended seminiferous tubules with hyperplastic germ cells contiguous with ovarian stroma and primordial follicles. The left gonad had scant ovarian stroma and embryonic remnants. Chromosome analyses showed mosaicism in both gonads: 45,X[17]/45,X,tas(Y;8(p11.32;p23.3[3]. This is the first case of coexisting CAH and 45,X/46,XY mosaicism reported in the English literature and the third case of a constitutional chromosome Y “jumping translocation.” Our report documents the medical and genetic complexity of children such as this one with ambiguous genitalia and discusses the need for a multidisciplinary team approach.

Multiple mouse chromosomal loci for dynein-based motility

Energy Technology Data Exchange (ETDEWEB)

Vaughan, K.T.; Mikami, Atsushi; Paschal, B.M. [Worcester Foundation for Biomedical Research, Shrewsbury, MA (United States)] [and others

1996-08-15

Dyneins are multisubunit mechanochemical enzymes capable of interacting with microtubules to generate force. Axonemal dyneins produce the motive force for ciliary and flagellar beating by inducing sliding between adjacent microtubules within the axoneme. Cytoplasmic dyneins translocate membranous organelles and chromosomes toward the minus ends of cytoplasmic microtubules. Dynactin is an accessory complex implicated in tethering cytoplasmic dynein to membranous organelles and mitotic kinetochores. In the studies described here, we have identified a number of new dynein genes and determined their mouse chromosomal locations by interspecific backcross analysis. We have also mapped several dynein and dynactin genes cloned previously. Our studies provide the first comprehensive attempt to map dynein and dynactin genes in mammals and provide a basis for the further analysis of dynein function in development and disease. 65 refs., 6 figs., 1 tab.

Meiosis-specific cohesin component, Stag3 is essential for maintaining centromere chromatid cohesion, and required for DNA repair and synapsis between homologous chromosomes.

Science.gov (United States)

Hopkins, Jessica; Hwang, Grace; Jacob, Justin; Sapp, Nicklas; Bedigian, Rick; Oka, Kazuhiro; Overbeek, Paul; Murray, Steve; Jordan, Philip W

2014-07-01

Cohesins are important for chromosome structure and chromosome segregation during mitosis and meiosis. Cohesins are composed of two structural maintenance of chromosomes (SMC1-SMC3) proteins that form a V-shaped heterodimer structure, which is bridged by a α-kleisin protein and a stromal antigen (STAG) protein. Previous studies in mouse have shown that there is one SMC1 protein (SMC1β), two α-kleisins (RAD21L and REC8) and one STAG protein (STAG3) that are meiosis-specific. During meiosis, homologous chromosomes must recombine with one another in the context of a tripartite structure known as the synaptonemal complex (SC). From interaction studies, it has been shown that there are at least four meiosis-specific forms of cohesin, which together with the mitotic cohesin complex, are lateral components of the SC. STAG3 is the only meiosis-specific subunit that is represented within all four meiosis-specific cohesin complexes. In Stag3 mutant germ cells, the protein level of other meiosis-specific cohesin subunits (SMC1β, RAD21L and REC8) is reduced, and their localization to chromosome axes is disrupted. In contrast, the mitotic cohesin complex remains intact and localizes robustly to the meiotic chromosome axes. The instability of meiosis-specific cohesins observed in Stag3 mutants results in aberrant DNA repair processes, and disruption of synapsis between homologous chromosomes. Furthermore, mutation of Stag3 results in perturbation of pericentromeric heterochromatin clustering, and disruption of centromere cohesion between sister chromatids during meiotic prophase. These defects result in early prophase I arrest and apoptosis in both male and female germ cells. The meiotic defects observed in Stag3 mutants are more severe when compared to single mutants for Smc1β, Rec8 and Rad21l, however they are not as severe as the Rec8, Rad21l double mutants. Taken together, our study demonstrates that STAG3 is required for the stability of all meiosis-specific cohesin

Meiosis-specific cohesin component, Stag3 is essential for maintaining centromere chromatid cohesion, and required for DNA repair and synapsis between homologous chromosomes.

Directory of Open Access Journals (Sweden)

Jessica Hopkins

2014-07-01

Full Text Available Cohesins are important for chromosome structure and chromosome segregation during mitosis and meiosis. Cohesins are composed of two structural maintenance of chromosomes (SMC1-SMC3 proteins that form a V-shaped heterodimer structure, which is bridged by a α-kleisin protein and a stromal antigen (STAG protein. Previous studies in mouse have shown that there is one SMC1 protein (SMC1β, two α-kleisins (RAD21L and REC8 and one STAG protein (STAG3 that are meiosis-specific. During meiosis, homologous chromosomes must recombine with one another in the context of a tripartite structure known as the synaptonemal complex (SC. From interaction studies, it has been shown that there are at least four meiosis-specific forms of cohesin, which together with the mitotic cohesin complex, are lateral components of the SC. STAG3 is the only meiosis-specific subunit that is represented within all four meiosis-specific cohesin complexes. In Stag3 mutant germ cells, the protein level of other meiosis-specific cohesin subunits (SMC1β, RAD21L and REC8 is reduced, and their localization to chromosome axes is disrupted. In contrast, the mitotic cohesin complex remains intact and localizes robustly to the meiotic chromosome axes. The instability of meiosis-specific cohesins observed in Stag3 mutants results in aberrant DNA repair processes, and disruption of synapsis between homologous chromosomes. Furthermore, mutation of Stag3 results in perturbation of pericentromeric heterochromatin clustering, and disruption of centromere cohesion between sister chromatids during meiotic prophase. These defects result in early prophase I arrest and apoptosis in both male and female germ cells. The meiotic defects observed in Stag3 mutants are more severe when compared to single mutants for Smc1β, Rec8 and Rad21l, however they are not as severe as the Rec8, Rad21l double mutants. Taken together, our study demonstrates that STAG3 is required for the stability of all meiosis

Structural variations of staphylococcal cassette chromosome mec Type IVa in Staphylococcus aureus clonal complex 8 and unrelated lineages

DEFF Research Database (Denmark)

Damborg, Peter Panduro; Bartels, Mette Damkjær; Boye, Kit

2011-01-01

PCR mapping of staphylococcal cassette chromosome mec type IVa and adjacent mobile elements in 94 methicillin-resistant Staphylococcus aureus (MRSA) strains identified two primary structures (A and B) that could be further classified into two (A1 and A2) and five (B1 to B5) variants, primarily...... based on structural differences in the orfX-J3 region. While spa type t008 (USA300) invariably contained the A variants, other spa types belonging to clonal complex 8 and unrelated lineages generally contained B variants. These findings have important implications for the typing and identification...

Global chromosomal structural instability in a subpopulation of starving Escherichia coli cells.

Directory of Open Access Journals (Sweden)

Dongxu Lin

2011-08-01

Full Text Available Copy-number variations (CNVs constitute very common differences between individual humans and possibly all genomes and may therefore be important fuel for evolution, yet how they form remains elusive. In starving Escherichia coli, gene amplification is induced by stress, controlled by the general stress response. Amplification has been detected only encompassing genes that confer a growth advantage when amplified. We studied the structure of stress-induced gene amplification in starving cells in the Lac assay in Escherichia coli by array comparative genomic hybridization (aCGH, with polymerase chain reaction (pcr and DNA sequencing to establish the structures generated. About 10% of 300 amplified isolates carried other chromosomal structural change in addition to amplification. Most of these were inversions and duplications associated with the amplification event. This complexity supports a mechanism similar to that seen in human non-recurrent copy number variants. We interpret these complex events in terms of repeated template switching during DNA replication. Importantly, we found a significant occurrence (6 out of 300 of chromosomal structural changes that were apparently not involved in the amplification event. These secondary changes were absent from 240 samples derived from starved cells not carrying amplification, suggesting that amplification happens in a differentiated subpopulation of stressed cells licensed for global chromosomal structural change and genomic instability. These data imply that chromosomal structural changes occur in bursts or showers of instability that may have the potential to drive rapid evolution.

Chromosomal rearrangement interferes with meiotic X chromosome inactivation

Czech Academy of Sciences Publication Activity Database

Homolka, David; Ivánek, Robert; Čapková, Jana; Jansa, Petr; Forejt, Jiří

2007-01-01

Roč. 17, č. 10 (2007), s. 1431-1437 ISSN 1088-9051 R&D Projects: GA MŠk(CZ) 1M0520; GA ČR GA301/06/1334; GA ČR GA301/07/1383 Grant - others:Howard Hughes Medical Institute(US) HHMI 55000306 Institutional research plan: CEZ:AV0Z50520514 Keywords : chromosomal translocations * meiotic X chromosome inactivation * spermatogenesis Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 11.224, year: 2007

Paternal isodisomy of chromosome 6 in association with a maternal supernumerary marker chromosome (6)

Energy Technology Data Exchange (ETDEWEB)

James, R.S.; Crolla, J.A.; Sitch, F.L. [Salisbury District Hospital, Wiltshire (United Kingdom)] [and others

1994-09-01

Uniparental disomy may arise by a number of different mechanisms of aneuploidy correction. A population that has been identified as being at increased risk of aneuploidy are those individuals bearing supernumerary marker chromosomes (SMCs). There have been a number of cases reported of trisomy 21 in association with bi-satellited marker chromosomes have described two individuals with small inv dup (15) markers. One had paternal isodisomy of chromosome 15 and Angelman syndrome. The other had maternal heterodisomy (15) and Prader-Willi syndrome. At the Wessex Regional Genetics Laboratory we have conducted a search for uniparental disomy of the normal homologues of the chromosomes from which SMCs originated. Our study population consists of 39 probands with SMCs originating from a number of different autosomes, including 17 with SMCs of chromosome 15 origin. Using PCR amplification of microsatellite repeat sequences located distal to the regions included in the SMCs we have determined the parental origin of the two normal homologues in each case. We have identified paternal isodisomy of chromosome 6 in a female child with a supernumerary marker ring chromosome 6 in approximately 70% of peripheral blood lymphocytes. The marker was found to be of maternal origin. This is the second case of paternal isodisomy of chromosome 6 to be reported, and the first in association with a SMC resulting in a partial trisomy for a portion of the short arm of chromosome 6. In spite of this, the patient appears to be functioning appropriately for her age.

Complex genetic architecture of cardiac disease in a wild type inbred strain of Drosophila melanogaster.

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Zhi Zhang

Full Text Available Natural populations of the fruit fly, Drosophila melanogaster, segregate genetic variation that leads to cardiac disease phenotypes. One nearly isogenic line from a North Carolina peach orchard, WE70, is shown to harbor two genetically distinct heart phenotypes: elevated incidence of arrhythmias, and a dramatically constricted heart diameter in both diastole and systole, with resemblance to restrictive cardiomyopathy in humans. Assuming the source to be rare variants of large effect, we performed Bulked Segregant Analysis using genomic DNA hybridization to Affymetrix chips to detect single feature polymorphisms, but found that the mutant phenotypes are more likely to have a polygenic basis. Further mapping efforts revealed a complex architecture wherein the constricted cardiomyopathy phenotype was observed in individual whole chromosome substitution lines, implying that variants on both major autosomes are sufficient to produce the phenotype. A panel of 170 Recombinant Inbred Lines (RIL was generated, and a small subset of mutant lines selected, but these each complemented both whole chromosome substitutions, implying a non-additive (epistatic contribution to the "disease" phenotype. Low coverage whole genome sequencing was also used to attempt to map chromosomal regions contributing to both the cardiomyopathy and arrhythmia, but a polygenic architecture had to be again inferred to be most likely. These results show that an apparently simple rare phenotype can have a complex genetic basis that would be refractory to mapping by deep sequencing in pedigrees. We present this as a cautionary tale regarding assumptions related to attempts to map new disease mutations on the assumption that probands carry a single causal mutation.

Gonadal sex chromosome complement in individuals with sex chromosomal and/or gonadal disorders

Energy Technology Data Exchange (ETDEWEB)

Bridge, J.A.; Sanger, W.G.; Seemayer, T. [Univ. of Nebraska Medical Center, Omaha, NE (United States)] [and others

1994-09-01

Gonadal abnormalities are characteristically seen in patients with sex chromosomal aneuploidy. Morphologically these abnormalities can be variable and are hypothesized to be dependent on the sex chromosomal consititution of the gonad (independent of the chromosomal complement of other tissues, such as peripheral blood lymphocytes). In this study, the gonadal sex chromosome complement was evaluated for potential mosaicism and correlated with the histopathology from 5 patients with known sex chromosomal and/or gonadal disorders. FISH techniques using X and Y chromosome specific probes were performed on nuclei extracted from paraffin embedded tissue. Gonadal tissue obtained from case 1 (a true hemaphroditic newborn) consisted of ovotestes and epididymis (left side) and ovary with fallopian tube (right side). Cytogenetic and FISH studies performed on blood, ovotestes and ovary revealed an XX complement. Cytogenetic analysis of blood from case 2, a 4-year-old with suspected Turner syndrome revealed 45,X/46,X,del(Y)(q11.21). FISH analysis of the resected gonads (histologically = immature testes) confirmed an X/XY mosaic complement. Histologically, the gonadal tissue was testicular. Severe autolysis prohibited successful analysis in the 2 remaining cases. In summary, molecular cytogenetic evaluation of gonadal tissue from individuals with sex chromosomal and/or gonadal disorders did not reveal tissue-specific anomalies which could account for differences observed pathologically.

The distribution of chromosome aberrations among chromosomes of karyotype in exposed human lymphocyte

International Nuclear Information System (INIS)

Que Tran; Tien Hoang Hung

1997-01-01

Induced chromosome aberrations (ch. ab.) in exposed Human peripheral blood lymphocyte have been used to assay radio.bio.doses, because of their characters such as: the maintaining Go phase in cell cycle in body, the distribution of cell in blood system and the distribution of ch. ab. in exposed cells of body and among chromosomes of karyotype. The frequency of ch. ab. reflected the quantity of radiation dose, dose rate and radiation energy. The dependence between radiation dose and frequency of ch. ab. was illustrated by the mathematic equations. The distribution of induced ch. ab. among the cells exposed to uniform radiation fields was Poisson's, but the distribution of ch. ab. among chromosomes in karyotype depended on radiation field and mononucleotid sequence of DNA molecular of each chromosome. The minimum influence of mononucleotid sequence of DNA molecular in inform ch. ab. will be advantageous state for dose-assessments. The location of induced ch. ab. in exposed Human lymphocyte had been determined by karyotype analyses. The data of statistic analyse had improved that the number of ch. ab. depended on the size of chromosomes in karyotype. The equal distribution of ch. ab.among chromosomes in karyotype provided the objectiveness and the accuracy of using the chromosomal aberrant analysis technique on bio-dosimetry. (author)

Genomic profiling using array comparative genomic hybridization define distinct subtypes of diffuse large b-cell lymphoma: a review of the literature

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Tirado Carlos A

2012-09-01

Full Text Available Abstract Diffuse large B-cell lymphoma (DLBCL is the most common type of non-Hodgkin Lymphoma comprising of greater than 30% of adult non-Hodgkin Lymphomas. DLBCL represents a diverse set of lymphomas, defined as diffuse proliferation of large B lymphoid cells. Numerous cytogenetic studies including karyotypes and fluorescent in situ hybridization (FISH, as well as morphological, biological, clinical, microarray and sequencing technologies have attempted to categorize DLBCL into morphological variants, molecular and immunophenotypic subgroups, as well as distinct disease entities. Despite such efforts, most lymphoma remains undistinguishable and falls into DLBCL, not otherwise specified (DLBCL-NOS. The advent of microarray-based studies (chromosome, RNA, gene expression, etc has provided a plethora of high-resolution data that could potentially facilitate the finer classification of DLBCL. This review covers the microarray data currently published for DLBCL. We will focus on these types of data; 1 array based CGH; 2 classical CGH; and 3 gene expression profiling studies. The aims of this review were three-fold: (1 to catalog chromosome loci that are present in at least 20% or more of distinct DLBCL subtypes; a detailed list of gains and losses for different subtypes was generated in a table form to illustrate specific chromosome loci affected in selected subtypes; (2 to determine common and distinct copy number alterations among the different subtypes and based on this information, characteristic and similar chromosome loci for the different subtypes were depicted in two separate chromosome ideograms; and, (3 to list re-classified subtypes and those that remained indistinguishable after review of the microarray data. To the best of our knowledge, this is the first effort to compile and review available literatures on microarray analysis data and their practical utility in classifying DLBCL subtypes. Although conventional cytogenetic methods such

Numerically abnormal chromosome constitutions in humans

Energy Technology Data Exchange (ETDEWEB)

NONE

1993-12-31

Chapter 24, discusses numerically abnormal chromosome constitutions in humans. This involves abnormalities of human chromosome number, including polyploidy (when the number of sets of chromosomes increases) and aneuploidy (when the number of individual normal chromosomes changes). Chapter sections discuss the following chromosomal abnormalities: human triploids, imprinting and uniparental disomy, human tetraploids, hydatidiform moles, anomalies caused by chromosomal imbalance, 13 trisomy (D{sub 1} trisomy, Patau syndrome), 21 trisomy (Down syndrome), 18 trisomy syndrome (Edwards syndrome), other autosomal aneuploidy syndromes, and spontaneous abortions. The chapter concludes with remarks on the nonrandom participation of chromosomes in trisomy. 69 refs., 3 figs., 4 tabs.

Study of male–mediated gene flow across a hybrid zone in the common shrew (Sorex araneus using Y chromosome

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Andrei V. Polyakov

2017-06-01

Full Text Available Despite many studies, the impact of chromosome rearrangements on gene flow between chromosome races of the common shrew (Sorex araneus Linnaeus, 1758 remains unclear. Interracial hybrids form meiotic chromosome complexes that are associated with reduced fertility. Nevertheless comprehensive investigations of autosomal and mitochondrial markers revealed weak or no barrier to gene flow between chromosomally divergent populations. In a narrow zone of contact between the Novosibirsk and Tomsk races hybrids are produced with extraordinarily complex configurations at meiosis I. Microsatellite markers have not revealed any barrier to gene flow, but the phenotypic differentiation between races is greater than may be expected if gene flow was unrestricted. To explore this contradiction we analyzed the distribution of the Y chromosome SNP markers within this hybrid zone. The Y chromosome variants in combination with race specific autosome complements allow backcrosses to be distinguished and their proportion among individuals within the hybrid zone to be evaluated. The balanced ratio of the Y variants observed among the pure race individuals as well as backcrosses reveals no male mediated barrier to gene flow. The impact of reproductive unfitness of backcrosses on gene flow is discussed as a possible mechanism of the preservation of race-specific morphology within the hybrid zone.

Genetic Analysis of Eight X-Chromosomal Short Tandem Repeat ...

African Journals Online (AJOL)

X-Chromosome short tandem repeat (STR) typing can complement existing DNA profiling protocols and can also offer useful information in cases of complex kinship analysis. This is the first population study of 8 X-linked STRs in Iraq. The purpose of this work was to provide a basic data of allele and haplotype frequency for ...

Novel transcripts discovered by mining genomic DNA from defined regions of bovine chromosome 6

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Eberlein Annett

2009-04-01

Full Text Available Abstract Background Linkage analyses strongly suggest a number of QTL for production, health and conformation traits in the middle part of bovine chromosome 6 (BTA6. The identification of the molecular background underlying the genetic variation at the QTL and subsequent functional studies require a well-annotated gene sequence map of the critical QTL intervals. To complete the sequence map of the defined subchromosomal regions on BTA6 poorly covered with comparative gene information, we focused on targeted isolation of transcribed sequences from bovine bacterial artificial chromosome (BAC clones mapped to the QTL intervals. Results Using the method of exon trapping, 92 unique exon trapping sequences (ETS were discovered in a chromosomal region of poor gene coverage. Sequence identity to the current NCBI sequence assembly for BTA6 was detected for 91% of unique ETS. Comparative sequence similarity search revealed that 11% of the isolated ETS displayed high similarity to genomic sequences located on the syntenic chromosomes of the human and mouse reference genome assemblies. Nearly a third of the ETS identified similar equivalent sequences in genomic sequence scaffolds from the alternative Celera-based sequence assembly of the human genome. Screening gene, EST, and protein databases detected 17% of ETS with identity to known transcribed sequences. Expression analysis of a subset of the ETS showed that most ETS (84% displayed a distinctive expression pattern in a multi-tissue panel of a lactating cow verifying their existence in the bovine transcriptome. Conclusion The results of our study demonstrate that the exon trapping method based on region-specific BAC clones is very useful for targeted screening for novel transcripts located within a defined chromosomal region being deficiently endowed with annotated gene information. The majority of identified ETS represents unknown noncoding sequences in intergenic regions on BTA6 displaying a

The synaptinemal complex in Rhoeo spathacea.

Science.gov (United States)

McQuade, H A; Wells, B

1975-03-01

The synaptinemal complex in meiocytes of Rhoeo spathacea is described. Unpaired zygotene chromosomes do not exhibit well defined axial cores under the ordinary fixations of electron microscopy and appear diffuse. However, the axial core is defined by ethanolic phosphotungstic acid (PTA) although it does not respond to uranyl-EDTA-lead. Thus the core appears to contain histone but not RNA and presents a condition which is modified later in pairing when lateral elements of the synaptinemal complex respond positively to both tests. The total number of attachments of synaptinemal complexes to the nuclear envelope was determined in several nuclei from serial sections. Eleven of the twelve possible attachments were found in one nucleus. It thus seems certain that all must be so attached. In the same manner all chromosomes can be seen to have an attachment to a chromocentre. Chromocentres are often very large and compound in that two kinds of heterochromatin can be distinguished. These states of chromatin within the chromocentre are considered to be a function of the degree of condensation. Segments of synaptinemal complexes are distributed randomly through sections of pachytene nuclei and long uncoiled segments of complexes are frequently found in or near the centres of median nuclear sections. Synaptinemal complexes are also found in chromocentres. Our findings suggest that on completion of pairing, which begins distally, homologous chromosomes in Rhoeo are paired throughout their entire lengths, rather than in small terminal segments only.

MHF1-2/CENP-S-X performs distinct roles in centromere metabolism and genetic recombination.

Science.gov (United States)

Bhattacharjee, Sonali; Osman, Fekret; Feeney, Laura; Lorenz, Alexander; Bryer, Claire; Whitby, Matthew C

2013-09-11

The histone-fold proteins Mhf1/CENP-S and Mhf2/CENP-X perform two important functions in vertebrate cells. First, they are components of the constitutive centromere-associated network, aiding kinetochore assembly and function. Second, they work with the FANCM DNA translocase to promote DNA repair. However, it has been unclear whether there is crosstalk between these roles. We show that Mhf1 and Mhf2 in fission yeast, as in vertebrates, serve a dual function, aiding DNA repair/recombination and localizing to centromeres to promote chromosome segregation. Importantly, these functions are distinct, with the former being dependent on their interaction with the FANCM orthologue Fml1 and the latter not. Together with Fml1, they play a second role in aiding chromosome segregation by processing sister chromatid junctions. However, a failure of this activity does not manifest dramatically increased levels of chromosome missegregation due to the Mus81-Eme1 endonuclease, which acts as a failsafe to resolve DNA junctions before the end of mitosis.

Wrestling with Chromosomes: The Roles of SUMO During Meiosis.

Science.gov (United States)

Nottke, Amanda C; Kim, Hyun-Min; Colaiácovo, Monica P

2017-01-01

Meiosis is a specialized form of cell division required for the formation of haploid gametes and therefore is essential for successful sexual reproduction. Various steps are exquisitely coordinated to ensure accurate chromosome segregation during meiosis, thereby promoting the formation of haploid gametes from diploid cells. Recent studies are demonstrating that an important form of regulation during meiosis is exerted by the post-translational protein modification known as sumoylation. Here, we review and discuss the various critical steps of meiosis in which SUMO-mediated regulation has been implicated thus far. These include the maintenance of meiotic centromeric heterochromatin , meiotic DNA double-strand break repair and homologous recombination, centromeric coupling, and the assembly of a proteinaceous scaffold between homologous chromosomes known as the synaptonemal complex.

Origin of amphibian and avian chromosomes by fission, fusion, and retention of ancestral chromosomes

Science.gov (United States)

Voss, Stephen R.; Kump, D. Kevin; Putta, Srikrishna; Pauly, Nathan; Reynolds, Anna; Henry, Rema J.; Basa, Saritha; Walker, John A.; Smith, Jeramiah J.

2011-01-01

Amphibian genomes differ greatly in DNA content and chromosome size, morphology, and number. Investigations of this diversity are needed to identify mechanisms that have shaped the evolution of vertebrate genomes. We used comparative mapping to investigate the organization of genes in the Mexican axolotl (Ambystoma mexicanum), a species that presents relatively few chromosomes (n = 14) and a gigantic genome (>20 pg/N). We show extensive conservation of synteny between Ambystoma, chicken, and human, and a positive correlation between the length of conserved segments and genome size. Ambystoma segments are estimated to be four to 51 times longer than homologous human and chicken segments. Strikingly, genes demarking the structures of 28 chicken chromosomes are ordered among linkage groups defining the Ambystoma genome, and we show that these same chromosomal segments are also conserved in a distantly related anuran amphibian (Xenopus tropicalis). Using linkage relationships from the amphibian maps, we predict that three chicken chromosomes originated by fusion, nine to 14 originated by fission, and 12–17 evolved directly from ancestral tetrapod chromosomes. We further show that some ancestral segments were fused prior to the divergence of salamanders and anurans, while others fused independently and randomly as chromosome numbers were reduced in lineages leading to Ambystoma and Xenopus. The maintenance of gene order relationships between chromosomal segments that have greatly expanded and contracted in salamander and chicken genomes, respectively, suggests selection to maintain synteny relationships and/or extremely low rates of chromosomal rearrangement. Overall, the results demonstrate the value of data from diverse, amphibian genomes in studies of vertebrate genome evolution. PMID:21482624

Molecular fundamentals of chromosomal mutagenesis

International Nuclear Information System (INIS)

Ganassi, E.Eh.; Zaichkina, S.I.; Malakhova, L.V.

1987-01-01

Precise quantitative correlation between the yield of chromosome structure damages and the yield of DNA damages is shown when comparing data on molecular and cytogenetic investigations carried out in cultural Mammalia cells. As the chromosome structure damage is to be connected with the damage of its carcass structure, then it is natural that DNA damage in loop regions is not to affect considerably the structure, while DNA damage lying on the loop base and connected with the chromosome carcass is to play a determining role in chromosomal mutagenesis. This DNA constitutes 1-2% from the total quantity of nuclear DNA. If one accepts that damages of these regions of DNA are ''hot'' points of chromosomal mutagenesis, then it becomes clear why 1-2% of preparation damages in a cell are realized in chromosome structural damages

Exchange of core chromosomes and horizontal transfer of lineage-specific chromosomes in Fusarium oxysporum

NARCIS (Netherlands)

Vlaardingerbroek, I.; Beerens, B.; Rose, L.; Fokkens, L.; Cornelissen, B.J.C.; Rep, M.

2016-01-01

Horizontal transfer of supernumerary or lineage-specific (LS) chromosomes has been described in a number of plant pathogenic filamentous fungi. So far it was not known whether transfer is restricted to chromosomes of certain size or properties, or whether 'core' chromosomes can also undergo

Chromosomal geometry in the interface from the frequency of the radiation induced chromosome aberrations

International Nuclear Information System (INIS)

Nasazzi, N.; Otero, D.; Di Giorgio, M.

1996-01-01

Ionizing radiation induces DNA double-strand breaks (DSBs) and their interaction and illegitimate recombination produces chromosomal aberrations. Stable chromosomal aberrations comprise inter-chromosomal events (translocations) and intra-chromosomal events (inversions). When DSBs induction and interaction is done at random, and the proximity effects are neglected, the expected relation between translocations and inversions is F=86, based on chromosome arm length. The number of translocations and inversions is analyzed by using G-banding in 16 lymphocytes cultures from blood samples acutely irradiated with γ-rays (dose range: 0,5 Gy - 3 Gy). The result obtained was: F=13,5, significantly smaller than F=86. Literature data show similar small F values, but strongly spread. The excess of inversions could be explained by a 'proximity effect', it means that more proximate DSBs have more interaction probability. Therefore, it is possible to postulate a special chromosome arrangement during irradiation and the subsequent interval. We propose a model where individual chromosomes show spherical confinement with some degree of overlapping and DSBs induction proportional to cross section. A DSBs interaction probability function with cut-off length= 1μ is assumed. According to our results, the confinement volume is ≅ 6.4% of the nuclear volume. Nevertheless, we presume that large spread in F data could be due to temporal variation in overlapping and spatial chromosomal confinement. (authors). 14 refs

mFISH analysis of chromosome aberrations in workers occupationally exposed to mixed radiation

Energy Technology Data Exchange (ETDEWEB)

Sotnik, Natalia V.; Osovets, Sergey V.; Azizova, Tamara V. [Southern Urals Biophysics Institute (SUBI), Ozyorsk, Chelyabinsk Region (Russian Federation); Scherthan, Harry [Bundeswehr Institute of Radiobiology Affiliated to the University of Ulm, Munich (Germany)

2014-05-15

We performed a study on the presence of chromosome aberrations in a cohort of plutonium workers of the Mayak production association (PA) with a mean age of 73.3 ± 7.2 years to see whether by multi-color fluorescence in situ hybridization (mFISH) translocation analysis can discriminate individuals who underwent occupational exposure with internal and/or external exposure to ionizing radiation 40 years ago. All Mayak PA workers were occupationally exposed to chronic internal alpha-radiation due to incorporated plutonium-239 and/or to external gamma-rays. First, we obtained the translocation yield in control individuals by mFISH to chromosome spreads of age-matched individuals and obtained background values that are similar to previously published values of an international study (Sigurdson et al. in Mutat Res 652:112-121, 2008). Workers who had absorbed a total dose of >0.5 Gy external gamma-rays to the red bone marrow (RBM) displayed a significantly higher frequency of stable chromosome aberrations relative to a group of workers exposed to <0.5 Gy gamma-rays total absorbed RBM dose. Thus, the translocation frequency may be considered to be a biological marker of external radiation exposure even years after the exposure. In a group of workers who were internally exposed and had incorporated plutonium-239 at a body burden >1.48 kBq, mFISH revealed a considerable number of cells with complex chromosomal rearrangements. Linear associations were observed for translocation yield with the absorbed RBM dose from external gamma-rays as well as for complex chromosomal rearrangements with the plutonium-239 body burden. (orig.)

Analysis of Chromosomal Aberrations after Low and High Dose Rate Gamma Irradiation in ATM or NBS Suppressed Human Fibroblast Cells

Science.gov (United States)

Hada, M.; Huff, J. L.; Patel, Z.; Pluth, J. M.; George, K. A.; Cucinotta, F. A.

2009-01-01

A detailed understanding of the biological effects of heavy nuclei is needed for space radiation protection and for cancer therapy. High-LET radiation produces more complex DNA lesions that may be non-repairable or that may require additional processing steps compared to endogenous DSBs, increasing the possibility of misrepair. Interplay between radiation sensitivity, dose, and radiation quality has not been studied extensively. Previously we studied chromosome aberrations induced by low- and high- LET radiation in several cell lines deficient in ATM (ataxia telangactasia mutated; product of the gene that is mutated in ataxia telangiectasia patients) or NBS (nibrin; product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase (DNA-PK) activity. We found that the yields of both simple and complex chromosomal aberrations were significantly increased in the DSB repair defective cells compared to normal cells. The increased aberrations observed for the ATM and NBS defective lines was due to a significantly larger quadratic dose-response term compared to normal fibroblasts for both simple and complex aberrations, while the linear dose-response term was significantly higher in NBS cells only for simple exchanges. These results point to the importance of the functions of ATM and NBS in chromatin modifications that function to facilitate correct DSB repair and minimize aberration formation. To further understand the sensitivity differences that were observed in ATM and NBS deficient cells, in this study, chromosomal aberration analysis was performed in normal lung fibroblast cells treated with KU-55933, a specific ATM kinase inhibitor, or Mirin, an MRN complex inhibitor involved in activation of ATM. We are also testing siRNA knockdown of these proteins. Normal and ATM or NBS suppressed cells were irradiated with gamma-rays and chromosomes were collected with a premature chromosome

Chromosome Territories

OpenAIRE

Cremer, Thomas; Cremer, Marion

2010-01-01

Chromosome territories (CTs) constitute a major feature of nuclear architecture. In a brief statement, the possible contribution of nuclear architecture studies to the field of epigenomics is considered, followed by a historical account of the CT concept and the final compelling experimental evidence of a territorial organization of chromosomes in all eukaryotes studied to date. Present knowledge of nonrandom CT arrangements, of the internal CT architecture, and of structural interactions wit...

Characterization and prognostic implication of 17 chromosome abnormalities in myelodysplastic syndrome.

Science.gov (United States)

Sánchez-Castro, Judit; Marco-Betés, Víctor; Gómez-Arbonés, Xavier; Arenillas, Leonor; Valcarcel, David; Vallespí, Teresa; Costa, Dolors; Nomdedeu, Benet; Jimenez, María José; Granada, Isabel; Grau, Javier; Ardanaz, María T; de la Serna, Javier; Carbonell, Félix; Cervera, José; Sierra, Adriana; Luño, Elisa; Cervero, Carlos J; Falantes, José; Calasanz, María J; González-Porrás, José R; Bailén, Alicia; Amigo, M Luz; Sanz, Guillermo; Solé, Francesc

2013-07-01

The prognosis of chromosome 17 (chr17) abnormalities in patients with primary myelodysplastic syndrome (MDS) remains unclear. The revised International Prognostic Scoring System (IPSS-R) includes these abnormalities within the intermediate cytogenetic risk group. This study assessed the impact on overall survival (OS) and risk of acute myeloid leukemia transformation (AMLt) of chr17 abnormalities in 88 patients with primary MDS. We have compared this group with 1346 patients with primary MDS and abnormal karyotype without chr17 involved. The alterations of chr17 should be considered within group of poor prognosis. The different types of alterations of chromosome 17 behave different prognosis. The study confirms the intermediate prognostic impact of the i(17q), as stated in IPSS-R. The results of the study, however, provide valuable new information on the prognostic impact of alterations of chromosome 17 in complex karyotypes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Chromosome-wise Protein Interaction Patterns and Their Impact on Functional Implications of Large-Scale Genomic Aberrations

DEFF Research Database (Denmark)

Kirk, Isa Kristina; Weinhold, Nils; Belling, Kirstine González-Izarzugaza

2017-01-01

Gene copy-number changes influence phenotypes through gene-dosage alteration and subsequent changes of protein complex stoichiometry. Human trisomies where gene copy numbers are increased uniformly over entire chromosomes provide generic cases for studying these relationships. In most trisomies......, gene and protein level alterations have fatal consequences. We used genome-wide protein-protein interaction data to identify chromosome-specific patterns of protein interactions. We found that some chromosomes encode proteins that interact infrequently with each other, chromosome 21 in particular. We...... combined the protein interaction data with transcriptome data from human brain tissue to investigate how this pattern of global interactions may affect cellular function. We identified highly connected proteins that also had coordinated gene expression. These proteins were associated with important...

High-Affinity Sites Form an Interaction Network to Facilitate Spreading of the MSL Complex across the X Chromosome in Drosophila

NARCIS (Netherlands)

Ramírez, Fidel; Lingg, Thomas; Toscano, Sarah; Lam, Kin Chung; Georgiev, Plamen; Chung, Ho-Ryun; Lajoie, Bryan R; de Wit, Elzo; Zhan, Ye; de Laat, Wouter; Dekker, Job; Manke, Thomas; Akhtar, Asifa

2015-01-01

Dosage compensation mechanisms provide a paradigm to study the contribution of chromosomal conformation toward targeting and spreading of epigenetic regulators over a specific chromosome. By using Hi-C and 4C analyses, we show that high-affinity sites (HAS), landing platforms of the male-specific

GSK-3 inhibitors induce chromosome instability

Directory of Open Access Journals (Sweden)

Staples Oliver D

2007-08-01

Full Text Available Abstract Background Several mechanisms operate during mitosis to ensure accurate chromosome segregation. However, during tumour evolution these mechanisms go awry resulting in chromosome instability. While several lines of evidence suggest that mutations in adenomatous polyposis coli (APC may promote chromosome instability, at least in colon cancer, the underlying mechanisms remain unclear. Here, we turn our attention to GSK-3 – a protein kinase, which in concert with APC, targets β-catenin for proteolysis – and ask whether GSK-3 is required for accurate chromosome segregation. Results To probe the role of GSK-3 in mitosis, we inhibited GSK-3 kinase activity in cells using a panel of small molecule inhibitors, including SB-415286, AR-A014418, 1-Azakenpaullone and CHIR99021. Analysis of synchronised HeLa cells shows that GSK-3 inhibitors do not prevent G1/S progression or cell division. They do, however, significantly delay mitotic exit, largely because inhibitor-treated cells have difficulty aligning all their chromosomes. Although bipolar spindles form and the majority of chromosomes biorient, one or more chromosomes often remain mono-oriented near the spindle poles. Despite a prolonged mitotic delay, anaphase frequently initiates without the last chromosome aligning, resulting in chromosome non-disjunction. To rule out the possibility of "off-target" effects, we also used RNA interference to selectively repress GSK-3β. Cells deficient for GSK-3β exhibit a similar chromosome alignment defect, with chromosomes clustered near the spindle poles. GSK-3β repression also results in cells accumulating micronuclei, a hallmark of chromosome missegregation. Conclusion Thus, not only do our observations indicate a role for GSK-3 in accurate chromosome segregation, but they also raise the possibility that, if used as therapeutic agents, GSK-3 inhibitors may induce unwanted side effects by inducing chromosome instability.

Dielectrophoretic manipulation of human chromosomes in microfluidic channels: extracting chromosome dielectric properties

DEFF Research Database (Denmark)

Clausen, Casper Hyttel; Dimaki, Maria; Buckley, Sonia

2011-01-01

An investigation of the dielectric properties of polyamine buffer prepared human chromosomes is presented in this paper. Chromosomes prepared in this buffer are only a few micrometers in size and shaped roughly like spherical discs. Dielectrophoresis was therefore chosen as the method...... of manipulation combined with a custom designed microfluidic system containing the required electrodes for dielectrophoresis experiments. Our results show that although this system is presently not able to distinguish between the different chromosomes, it can provide average data for the dielectric properties...... of human chromosomes in polyamine buffer. These can then be used to optimize system designs for further characterization and even sorting. The experimental data from the dielectrophoretic manipulation were combined with theoretical calculations to extract a range of values for the permittivity...

Evolutionary and dispersal history of Triatoma infestans, main vector of Chagas disease, by chromosomal markers.

Science.gov (United States)

Panzera, Francisco; Ferreiro, María J; Pita, Sebastián; Calleros, Lucía; Pérez, Ruben; Basmadjián, Yester; Guevara, Yenny; Brenière, Simone Frédérique; Panzera, Yanina

2014-10-01

Chagas disease, one of the most important vector-borne diseases in the Americas, is caused by Trypanosoma cruzi and transmitted to humans by insects of the subfamily Triatominae. An effective control of this disease depends on elimination of vectors through spraying with insecticides. Genetic research can help insect control programs by identifying and characterizing vector populations. In southern Latin America, Triatoma infestans is the main vector and presents two distinct lineages, known as Andean and non-Andean chromosomal groups, that are highly differentiated by the amount of heterochromatin and genome size. Analyses with nuclear and mitochondrial sequences are not conclusive about resolving the origin and spread of T. infestans. The present paper includes the analyses of karyotypes, heterochromatin distribution and chromosomal mapping of the major ribosomal cluster (45S rDNA) to specimens throughout the distribution range of this species, including pyrethroid-resistant populations. A total of 417 specimens from seven different countries were analyzed. We show an unusual wide rDNA variability related to number and chromosomal position of the ribosomal genes, never before reported in species with holocentric chromosomes. Considering the chromosomal groups previously described, the ribosomal patterns are associated with a particular geographic distribution. Our results reveal that the differentiation process between both T. infestans chromosomal groups has involved significant genomic reorganization of essential coding sequences, besides the changes in heterochromatin and genomic size previously reported. The chromosomal markers also allowed us to detect the existence of a hybrid zone occupied by individuals derived from crosses between both chromosomal groups. Our genetic studies support the hypothesis of an Andean origin for T. infestans, and suggest that pyrethroid-resistant populations from the Argentinean-Bolivian border are most likely the result of

Evaluation of an automated karyotyping system for chromosome aberration analysis

International Nuclear Information System (INIS)

Prichard, H.M.

1987-01-01

Chromosome aberration analysis is a promising complement to conventional radiation dosimetry, particularly in the complex radiation fields encountered in the space environment. The capabilities of a recently developed automated karyotyping system were evaluated both to determine current capabilities and limitations and to suggest areas where future development should be emphasized. Cells exposed to radiometric chemicals and to photon and particulate radiation were evaluated by manual inspection and by automated karyotyping. It was demonstrated that the evaluated programs were appropriate for image digitization, storage, and transmission. However, automated and semi-automated scoring techniques must be advanced significantly if in-flight chromosome aberration analysis is to be practical. A degree of artificial intelligence may be necessary to realize this goal

The relationships among lemons, limes and citron: a chromosomal comparison.

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Carvalho, R; Soares Filho, W S; Brasileiro-Vidal, A C; Guerra, M

2005-01-01

Lemons, limes and citron constitute a group of closely related Citrus species, whose species delimitations and taxonomic relationships are unclear. In order to identify karyotypic similarities and species relationships within this group, the CMA+/DAPI- banding pattern and the distribution of the 5S and 45S rDNA sites of 10 accessions of lime, lemon, and citron were investigated. The four cultivars of C. limon analyzed showed the same pattern of CMA+ bands and rDNA sites, suggesting that they originated from a single germplasm, later differentiated by distinct somatic mutations. The lemons C. jambhiri, C. limonia and C. volkameriana displayed karyotypes very similar to each other, but they differed from C. limon by the absence of a single chromosome with one band in each telomere. The limes, C. aurantifolia and C. limettioides, seemed less related to each other and exhibited different heteromorphic chromosome pairs. In C. aurantifolia, the presence of a chromosome type unknown in all other Citrus species cytologically known so far supports the assumption that this accession may be derived from a hybrid with a species from the subgenus Papeda or from another genus. Citrus medica was the only homozygous accession of this group and all of its chromosome types were clearly represented in limes and lemons, some of them forming heteromorphic pairs. The analysis of the distribution of rDNA sites allowed a further refinement of the comparison among accessions. The lemons and limes were heterozygous for all rDNA sites, whereas C. medica was entirely homozygous. These data support the hypothesis that C. medica is a true species while the other nine accessions are hybrids. Copyright 2005 S. Karger AG, Basel.

Mapping the pericentric heterochromatin by comparative genomic hybridization analysis and chromosome deletions in Drosophila melanogaster.

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He, Bing; Caudy, Amy; Parsons, Lance; Rosebrock, Adam; Pane, Attilio; Raj, Sandeep; Wieschaus, Eric

2012-12-01

Heterochromatin represents a significant portion of eukaryotic genomes and has essential structural and regulatory functions. Its molecular organization is largely unknown due to difficulties in sequencing through and assembling repetitive sequences enriched in the heterochromatin. Here we developed a novel strategy using chromosomal rearrangements and embryonic phenotypes to position unmapped Drosophila melanogaster heterochromatic sequence to specific chromosomal regions. By excluding sequences that can be mapped to the assembled euchromatic arms, we identified sequences that are specific to heterochromatin and used them to design heterochromatin specific probes ("H-probes") for microarray. By comparative genomic hybridization (CGH) analyses of embryos deficient for each chromosome or chromosome arm, we were able to map most of our H-probes to specific chromosome arms. We also positioned sequences mapped to the second and X chromosomes to finer intervals by analyzing smaller deletions with breakpoints in heterochromatin. Using this approach, we were able to map >40% (13.9 Mb) of the previously unmapped heterochromatin sequences assembled by the whole-genome sequencing effort on arm U and arm Uextra to specific locations. We also identified and mapped 110 kb of novel heterochromatic sequences. Subsequent analyses revealed that sequences located within different heterochromatic regions have distinct properties, such as sequence composition, degree of repetitiveness, and level of underreplication in polytenized tissues. Surprisingly, although heterochromatin is generally considered to be transcriptionally silent, we detected region-specific temporal patterns of transcription in heterochromatin during oogenesis and early embryonic development. Our study provides a useful approach to elucidate the molecular organization and function of heterochromatin and reveals region-specific variation of heterochromatin.

Mechanisms of ring chromosome formation in 11 cases of human ring chromosome 21

DEFF Research Database (Denmark)

McGinniss, M J; Kazazian, H H; Stetten, G

1992-01-01

We studied the mechanism of ring chromosome 21 (r(21)) formation in 13 patients (11 unique r(21)s), consisting of 7 from five families with familial r(21) and 6 with de novo r(21). The copy number of chromosome 21 sequences in the rings of these patients was determined by quantitative dosage......), resulting in deletion of varying amounts of 21q22.1 to 21qter. The data from one individual who had a Down syndrome phenotype were consistent with asymmetric breakage and reunion of 21q sequences from an intermediate isochromosome or Robertsonian translocation chromosome as reported by Wong et al. Another......). The phenotype of patients correlated well with the extent of deletion or duplication of chromosome 21 sequences. These data demonstrate three mechanisms of r(21) formation and show that the phenotype of r(21) patients varies with the extent of chromosome 21 monosomy or trisomy....

Distinct evolutionary mechanisms for genomic imbalances in high-risk and low-risk neuroblastomas

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Gisselsson David

2007-09-01

Full Text Available Abstract Background Neuroblastoma (NB is the most common extracranial solid tumour of childhood. Several genomic imbalances correlate to prognosis in NB, with structural rearrangements, including gene amplification, in a near-diploid setting typically signifying high-risk tumours and numerical changes in a near-triploid setting signifying low-risk tumours. Little is known about the temporal sequence in which these imbalances occur during the carcinogenic process. Methods We have reconstructed the appearance of cytogenetic imbalances in 270 NBs by first grouping tumours and imbalances through principal component analysis and then using the number of imbalances in each tumour as an indicator of evolutionary progression. Results Tumours clustered in four sub-groups, dominated respectively by (1 gene amplification in double minute chromosomes and few other aberrations, (2 gene amplification and loss of 1p sequences, (3 loss of 1p and other structural aberrations including gain of 17q, and (4 whole-chromosome gains and losses. Temporal analysis showed that the structural changes in groups 1–3 were acquired in a step-wise fashion, with loss of 1p sequences and the emergence of double minute chromosomes as the earliest cytogenetic events. In contrast, the gains and losses of whole chromosomes in group 4 occurred through multiple simultaneous events leading to a near-triploid chromosome number. Conclusion The finding of different temporal patterns for the acquisition of genomic imbalances in high-risk and low-risk NBs lends strong support to the hypothesis that these tumours are biologically diverse entities, evolving through distinct genetic mechanisms.

Tumor-specific chromosome mis-segregation controls cancer plasticity by maintaining tumor heterogeneity.

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Yuanjie Hu

Full Text Available Aneuploidy with chromosome instability is a cancer hallmark. We studied chromosome 7 (Chr7 copy number variation (CNV in gliomas and in primary cultures derived from them. We found tumor heterogeneity with cells having Chr7-CNV commonly occurs in gliomas, with a higher percentage of cells in high-grade gliomas carrying more than 2 copies of Chr7, as compared to low-grade gliomas. Interestingly, all Chr7-aneuploid cell types in the parental culture of established glioma cell lines reappeared in single-cell-derived subcultures. We then characterized the biology of three syngeneic glioma cultures dominated by different Chr7-aneuploid cell types. We found phenotypic divergence for cells following Chr7 mis-segregation, which benefited overall tumor growth in vitro and in vivo. Mathematical modeling suggested the involvement of chromosome instability and interactions among cell subpopulations in restoring the optimal equilibrium of tumor cell types. Both our experimental data and mathematical modeling demonstrated that the complexity of tumor heterogeneity could be enhanced by the existence of chromosomes with structural abnormality, in addition to their mis-segregations. Overall, our findings show, for the first time, the involvement of chromosome instability in maintaining tumor heterogeneity, which underlies the enhanced growth, persistence and treatment resistance of cancers.

Discovery-based protein expression profiling identifies distinct subgroups and pathways in leiomyosarcomas

DEFF Research Database (Denmark)

Kirik, Ufuk; Hansson, Karin; Krogh, Morten

2014-01-01

UNLABELLED: Soft tissue sarcomas (STS) are malignant tumors of mesenchymal origin. A substantial portion of these tumors exhibits complex karyotypes and lack characterized chromosomal aberrations. Owing to such properties, both histopathologic and molecular classification of these tumors has been...

Simultaneous regression of Philadelphia chromosome and multiple nonrecurrent clonal chromosomal abnormalities with imatinib mesylate in a patient autografted 22 years before for chronic myelogenous leukemia.

Science.gov (United States)

Van Den Akker, J; Coppo, P; Portnoï, M F; Barbu, V; Bories, D; Gorin, N C

2007-09-01

A 31-year-old patient developed chronic myelogenous leukemia (CML) in November, 1983. In November 1984, following a diagnosis of acceleration, he received an autologous hemopoietic transplant after conditioning with cyclophosphamide and total body irradiation. The autologous marrow was purged with mafosfamide. Over 20 years, the patient remained in chronic phase of CML. Multiple nonrecurrent clonal chromosomal abnormalities appeared leading to a very complex karyotype, including among others involvement of chromosomes 1, 7, 9, 13, 19, and X. Fluorescent in situ hybridization showed that the two chromosomes 9 were involved. Acute myeloid crisis was diagnosed in February, 2004. Treatment with imatinib mesylate resulted within 6 months in a total disappearance of all chromosomal abnormalities with a complete cytogenetic and molecular response, which persists 3 years later. We question whether the ex vivo purging procedure with mafosfamide has favored the occurrence of these particular cytogenetic abnormalities (with no independent oncogenic potential) within the original leukemic stem cell pool. It remains unclear whether the autologous transplantation has indeed resulted into some prolongation of the duration of the chronic phase, which lasted for 20 years. At time of acute crisis, the dramatic response to imatinib mesylate leading to a complete cytogenetic and molecular response is noteworthy.

Chromosome analysis of arsenic affected cattle

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S. Shekhar

2014-10-01

Full Text Available Aim: The aim was to study the chromosome analysis of arsenic affected cattle. Materials and Methods: 27 female cattle (21 arsenic affected and 6 normal were selected for cytogenetical study. The blood samples were collected, incubated, and cultured using appropriate media and specific methods. The samples were analyzed for chromosome number and morphology, relative length of the chromosome, arm ratio, and centromere index of X chromosome and chromosomal abnormalities in arsenic affected cattle to that of normal ones. Results: The diploid number of metaphase chromosomes in arsenic affected cattle as well as in normal cattle were all 2n=60, 58 being autosomes and 2 being sex chromosomes. From the centromeric position, karyotyping studies revealed that all the 29 pair of autosomes was found to be acrocentric or telocentric, and the sex chromosomes (XX were submetacentric in both normal and arsenic affected cattle. The relative length of all the autosome pairs and sex chrosomosome pair was found to be higher in normal than that of arsenic affected cattle. The mean arm ratio of X-chromosome was higher in normal than that of arsenic affected cattle, but it is reverse in case of centromere index value of X-chromosome. There was no significant difference of arm ratio and centromere index of X-chromosomes between arsenic affected and normal cattle. No chromosomal abnormalities were found in arsenic affected cattle. Conclusion: The chromosome analysis of arsenic affected cattle in West Bengal reported for the first time in this present study which may serve as a guideline for future studies in other species. These reference values will also help in comparison of cytological studies of arsenic affected cattle to that of various toxicants.

High chromosomal instability in workers occupationally exposed to solvents and paint removers.

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Villalba-Campos, Mónica; Chuaire-Noack, Lilian; Sánchez-Corredor, Magda Carolina; Rondón-Lagos, Milena

2016-01-01

Painters are exposed to an extensive variety of harmful substances like aromatic hydrocarbons used as solvents and paint removers, some of which have shown clastogenic activity. These substances constitute a complex mixture of chemicals which contain well-known genotoxicants, such as Benzene, Toluene and Xylene. Thus, chronic occupational exposure to such substances may be considered to possess genotoxic risk. In Colombia the information available around the genotoxic damage (Chromosomal and DNA damage) in car paint shop workers is limited and the knowledge of this damage could contribute not only to a better understanding of the carcinogenic effect of this kind of substances but also could be used as biomarkers of occupational exposure to genotoxic agents. In this study, the genotoxic effect of aromatic hydrocarbons was assessed in peripheral blood lymphocytes of 24 workers occupationally exposed and 24 unexposed donors, by using Cytogenetic analysis and comet assay. A high frequency of Chromosomal alterations was found in the exposed group in comparison with those observed in the unexposed group. Among the total of CAs observed in the exposed group, fragilities were most frequently found (100 %), followed by chromosomal breaks (58 %), structural (41.2 %) and numerical chromosomal alterations (21 %). Numerical chromosomal alterations, fragilities and chromosomal breaks showed significant differences between exposed and unexposed groups. Among the fragilities, fra(9)(q12) was the most frequently observed. DNA damage index was also significantly higher in the exposed group compared to the unexposed group (p car paint shops workers and are also indicative of high chromosomal instability. The high frequency of both Chromosomal Alterations and DNA Damage Index observed in this study indicates an urgent need of intervention not only to prevent the increased risk of developing cancer but also to the application of strict health control and motivation to the use of

Meiotic transmission of Drosophila pseudoobscura chromosomal arrangements.

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Richard P Meisel

Full Text Available Drosophila pseudoobscura harbors a rich gene arrangement polymorphism on the third chromosome generated by a series of overlapping paracentric inversions. The arrangements suppress recombination in heterokaryotypic individuals, which allows for the selective maintenance of coadapted gene complexes. Previous mapping experiments used to determine the degree to which recombination is suppressed in gene arrangement heterozygotes produced non-recombinant progeny in non-Mendelian ratios. The deviations from Mendelian expectations could be the result of viability differences between wild and mutant chromosomes, meiotic drive because of achiasmate pairing of homologues in heterokaryotypic females during meiosis, or a combination of both mechanisms. The possibility that the frequencies of the chromosomal arrangements in natural populations are affected by mechanisms other than adaptive selection led us to consider these hypotheses. We performed reciprocal crosses involving both heterozygous males and females to determine if the frequency of the non-recombinant progeny deviates significantly from Mendelian expectations and if the frequencies deviate between reciprocal crosses. We failed to observe non-Mendelian ratios in multiple crosses, and the frequency of the non-recombinant classes differed in only one of five pairs of reciprocal crosses despite sufficient power to detect these differences in all crosses. Our results indicate that deviations from Mendelian expectations in recombination experiments involving the D. pseudoobscura inversion system are most likely due to fitness differences of gene arrangement karyotypes in different environments.

Chromosomal Aberrations in DNA Repair Defective Cell Lines: Comparisons of Dose Rate and Radiation Quality

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George, K. A.; Hada, M.; Patel, Z.; Huff, J.; Pluth, J. M.; Cucinotta, F. A.

2009-01-01

Chromosome aberration yields were assessed in DNA double-strand break repair (DSB) deficient cells after acute doses of gamma-rays or high-LET iron nuclei, or low dose-rate (0.018 Gy/hr) gamma-rays. We studied several cell lines including fibroblasts deficient in ATM (product of the gene that is mutated in ataxia telangiectasia patients) or NBS (product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase, DNA-PK activity. Chromosomes were analyzed using the fluorescence in-situ hybridization (FISH) chromosome painting method in cells at the first division post-irradiation and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma radiation induced higher yields of both simple and complex exchanges in the DSB repair defective cells than in the normal cells. The quadratic dose-response terms for both chromosome exchange types were significantly higher for the ATM and NBS defective lines than for normal fibroblasts. However, the linear dose-response term was significantly higher only for simple exchanges in the NBS cells. Large increases in the quadratic dose response terms indicate the important roles of ATM and NBS in chromatin modifications that facilitate correct DSB repair and minimize aberration formation. Differences in the response of AT and NBS deficient cells at lower doses suggests important questions about the applicability of observations of radiation sensitivity at high dose to low dose exposures. For all iron nuclei irradiated cells, regression models preferred purely linear and quadratic dose responses for simple and complex exchanges, respectively. All the DNA repair defective cell lines had lower Relative biological effectiveness (RBE) values than normal cells, the lowest being for the DNA-PK-deficient cells, which was near unity. To further

Moderate repetitions (mobile elements) and hot points of chromosomal mutagenesis in Drozophila melanogaster

International Nuclear Information System (INIS)

Aleksandrova, M.V.; Sevan'kaev, A.V.; Aleksandrov, I.D.

1989-01-01

The results of experimental examination of hypothesis on mobile elements (ME) as target for radiation-induced chromosomal mutagenesis do not confirm it in this direct variant though indicate on the presence of nonincidental connection between sites of ME localization of certain type and points of chromosomal mutagenesis are presented. The presented regularity is explained by assumption that settling of the ME by genome is going along postulated static chromomer-binding-DNA complexes, playing an important role in space organization of interphase chromatin. 11 refs.; 2 figs.; 2 tabs

Horse domestication and conservation genetics of Przewalski's horse inferred from sex chromosomal and autosomal sequences.

Science.gov (United States)

Lau, Allison N; Peng, Lei; Goto, Hiroki; Chemnick, Leona; Ryder, Oliver A; Makova, Kateryna D

2009-01-01

Despite their ability to interbreed and produce fertile offspring, there is continued disagreement about the genetic relationship of the domestic horse (Equus caballus) to its endangered wild relative, Przewalski's horse (Equus przewalskii). Analyses have differed as to whether or not Przewalski's horse is placed phylogenetically as a separate sister group to domestic horses. Because Przewalski's horse and domestic horse are so closely related, genetic data can also be used to infer domestication-specific differences between the two. To investigate the genetic relationship of Przewalski's horse to the domestic horse and to address whether evolution of the domestic horse is driven by males or females, five homologous introns (a total of approximately 3 kb) were sequenced on the X and Y chromosomes in two Przewalski's horses and three breeds of domestic horses: Arabian horse, Mongolian domestic horse, and Dartmoor pony. Five autosomal introns (a total of approximately 6 kb) were sequenced for these horses as well. The sequences of sex chromosomal and autosomal introns were used to determine nucleotide diversity and the forces driving evolution in these species. As a result, X chromosomal and autosomal data do not place Przewalski's horses in a separate clade within phylogenetic trees for horses, suggesting a close relationship between domestic and Przewalski's horses. It was also found that there was a lack of nucleotide diversity on the Y chromosome and higher nucleotide diversity than expected on the X chromosome in domestic horses as compared with the Y chromosome and autosomes. This supports the hypothesis that very few male horses along with numerous female horses founded the various domestic horse breeds. Patterns of nucleotide diversity among different types of chromosomes were distinct for Przewalski's in contrast to domestic horses, supporting unique evolutionary histories of the two species.

The Biological Effectiveness of Accelerated Particles for the Induction of Chromosome Damage: Track Structure Effects and Cytogenetic Signatures of High-LET Exposure

Science.gov (United States)

George, K.; Hada, M.; Chappell, L.; Cucinotta, F. A.

2012-01-01

Track structure models predict that at a fixed value of LET, particles with lower charge number, Z will have a higher biological effectiveness compared to particles with a higher Z. In this report we investigated how track structure effects induction of chromosomal aberration in human cells. Human lymphocytes were irradiated in vitro with various energies of accelerated iron, silicon, neon, or titanium ions and chromosome damage was assessed in using three color FISH chromosome painting in chemically induced PCC samples collected a first cell division post irradiation. The LET values for these ions ranged from 30 to 195 keV/micrometers. Of the particles studied, Neon ions have the highest biological effectiveness for induction of total chromosome damage, which is consistent with track structure model predictions. For complex-type exchanges 64 MeV/ u Neon and 450 MeV/u Iron were equally effective and induced the most complex damage. In addition we present data on chromosomes exchanges induced by six different energies of protons (5 MeV/u to 2.5 GeV/u). The linear dose response term was similar for all energies of protons suggesting that the effect of the higher LET at low proton energies is balanced by the production of nuclear secondaries from the high energy protons. All energies of protons have a much higher percentage of complex-type chromosome exchanges than gamma rays, signifying a cytogenetic signature for proton exposures.

Chromosome heteromorphisms in the Japanese, 3

International Nuclear Information System (INIS)

Sofuni, Toshio; Awa, A.A.

1982-12-01

The type and frequency of chromosome variants detected by the C-staining method were ascertained in 1,857 individuals residing in Hiroshima. The most frequent heteromorphic variant was the total inversion of the C-band in chromosome 9 found in 27 individuals (1.45%). The total inversion of the C-band in chromosome 1 was not seen in this sample, but the partial inversion of the C-band in chromosome 1 was found in 18 persons (0.97%). Partial inversion was also detected in the C-band in chromosome 9 in 22 individuals (1.18%). In chromosome 16, neither total nor partial inversion of the C-band was observed in the present study. The frequencies of chromosomes 1, 9, and 16 with a very large C-band were 0.70%, 0.22%, and 0.54%, respectively. Aside from these (1, 9, and 16) a very large C-band was found occasionally in chromosomes 4, 5, 6, 11, 12, 14, and 15, and an unusual insertion of the Y chromosome was observed. A total of 128 C-band variants (6.89%) was found in the 1,857 Hiroshima residents. (author)

Diversity and chromosomal evolution in the genus Ancistrus Kner, 1854 (Loricariidae: Ancistrini from three hydrographic basins of Mato Grosso State, Brazil

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Sandra Mariotto

Full Text Available Cytogenetic analyses were carried out in 117 specimens of seven species of the genus Ancistrus from three hydrographic in Mato Grosso State: Paraguay, Araguaia-Tocantins and Amazon basins. Conventional cytogenetic techniques were used to obtain mitotic chromosomes. C-banding was performed to detect heterochromatic regions and silver nitrate staining was used to identify nucleolar organizer regions (Ag-NORs. The counted and paired chromosomes revealed diploid numbers ranging from 2n = 40 to 2n = 54 with karyotype formulae varying from FN = 80 to FN = 86. Single marks in distinct chromosomes identified the nucleolar organizer regions. The constitutive heterochromatin was scarce in the diploid number from 2n = 50 to 2n = 54 and conspicuous blocks were observed in a single species with 2n = 40 chromosomes. These data corroborate the hypotheses of reduction of diploid number in species with derived features such as presence of sex chromosomes and polymorphisms, besides allowing inferences about the evolutionary mechanisms and the ancestor karyotype that favored the diversification of this important genus in the tribe Ancistrini.

Semi-automatic laser beam microdissection of the Y chromosome and analysis of Y chromosome DNA in a dioecious plant, Silene latifolia

International Nuclear Information System (INIS)

Matsunaga, S.; Kawano, S.; Michimoto, T.; Higashiyama, T.; Nakao, S.; Sakai, A.; Kuroiwa, T.

1999-01-01

Silene latifolia has heteromorphic sex chromosomes, the X and Y chromosomes. The Y chromosome, which is thought to carry the male determining gene, was isolated by UV laser microdissection and amplified by degenerate oligonucleotide-primed PCR. In situ chromosome suppression of the amplified Y chromosome DNA in the presence of female genomic DNA as a competitor showed that the microdissected Y chromosome DNA did not specifically hybridize to the Y chromosome, but-hybridized to all chromosomes. This result suggests that the Y chromosome does not contain Y chromosome-enriched repetitive sequences. A repetitive sequence in the microdissected Y chromosome, RMY1, was isolated while screening repetitive sequences in the amplified Y chromosome. Part of the nucleotide sequence shared a similarity to that of X-43.1, which was isolated from microdissected X chromosomes. Since fluorescence in situ hybridization analysis with RMY1 demonstrated that RMY1 was localized at the ends of the chromosome, RMY1 may be a subtelomeric repetitive sequence. Regarding the sex chromosomes, RMY1 was detected at both ends of the X chromosome and at one end near the pseudoautosomal region of the Y chromosome. The different localization of RMY1 on the sex chromosomes provides a clue to the problem of how the sex chromosomes arose from autosomes

The Argonaute CSR-1 and its 22G-RNA cofactors are required for holocentric chromosome segregation.

Science.gov (United States)

Claycomb, Julie M; Batista, Pedro J; Pang, Ka Ming; Gu, Weifeng; Vasale, Jessica J; van Wolfswinkel, Josien C; Chaves, Daniel A; Shirayama, Masaki; Mitani, Shohei; Ketting, René F; Conte, Darryl; Mello, Craig C

2009-10-02

RNAi-related pathways regulate diverse processes, from developmental timing to transposon silencing. Here, we show that in C. elegans the Argonaute CSR-1, the RNA-dependent RNA polymerase EGO-1, the Dicer-related helicase DRH-3, and the Tudor-domain protein EKL-1 localize to chromosomes and are required for proper chromosome segregation. In the absence of these factors chromosomes fail to align at the metaphase plate and kinetochores do not orient to opposing spindle poles. Surprisingly, the CSR-1-interacting small RNAs (22G-RNAs) are antisense to thousands of germline-expressed protein-coding genes. Nematodes assemble holocentric chromosomes in which continuous kinetochores must span the expressed domains of the genome. We show that CSR-1 interacts with chromatin at target loci but does not downregulate target mRNA or protein levels. Instead, our findings support a model in which CSR-1 complexes target protein-coding domains to promote their proper organization within the holocentric chromosomes of C. elegans.

An Atomic Force Microscopical Study of the Synaptonemal Complex

NARCIS (Netherlands)

Putman, C.A.J.; Putman, C.A.J.; Dietrich, A.J.J.; de Grooth, B.G.; van Marle, J.; Heyting, C.; van Hulst, N.F.; Greve, Jan

1993-01-01

The chromosomal structure which is specific for meiosis, the synaptonemal complex (SC), plays a major role in chromosome pairing and the recombination of genetic material. The SC was studied using atomic force microscopy (AFM). The results of this study confirm the results of light and electron

Chromosomal instability induced by ionizing radiation

International Nuclear Information System (INIS)

Morgan, W.F.; Marder, B.A.; Day, J.P.

1995-01-01

There is accumulating evidence indicating genomic instability can manifest multiple generations after cellular exposure to DNA damaging agents. For instance, some cells surviving exposure to ionizing radiations show delayed reproductive cell death, delayed mutation and / or delayed chromosomal instability. Such instability, especially chromosome destabilization has been implicated in mutation, gene amplification, cellular transformation, and cell killing. To investigate chromosomal instability following DNA damage, we have used fluorescence in situ hybridization to detect chromosomal rearrangements in a human/hamster somatic hybrid cell line following exposure to ionizing radiation. Delayed chromosomal instability was detected when multiple populations of uniquely arranged metaphases were observed in clonal isolates raised from single cells. The relationship between delayed chromosomal destabilization and other endpoints of genomic instability, namely; delayed mutation and gene amplification will be discussed, as will the potential cytogenetic and molecular mechanisms contributing to delayed chromosomal instability

The two different isoforms of the RSC chromatin remodeling complex play distinct roles in DNA damage responses.

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Anna L Chambers

Full Text Available The RSC chromatin remodeling complex has been implicated in contributing to DNA double-strand break (DSB repair in a number of studies. Both survival and levels of H2A phosphorylation in response to damage are reduced in the absence of RSC. Importantly, there is evidence for two isoforms of this complex, defined by the presence of either Rsc1 or Rsc2. Here, we investigated whether the two isoforms of RSC provide distinct contributions to DNA damage responses. First, we established that the two isoforms of RSC differ in the presence of Rsc1 or Rsc2 but otherwise have the same subunit composition. We found that both rsc1 and rsc2 mutant strains have intact DNA damage-induced checkpoint activity and transcriptional induction. In addition, both strains show reduced non-homologous end joining activity and have a similar spectrum of DSB repair junctions, suggesting perhaps that the two complexes provide the same functions. However, the hypersensitivity of a rsc1 strain cannot be complemented with an extra copy of RSC2, and likewise, the hypersensitivity of the rsc2 strain remains unchanged when an additional copy of RSC1 is present, indicating that the two proteins are unable to functionally compensate for one another in DNA damage responses. Rsc1, but not Rsc2, is required for nucleosome sliding flanking a DNA DSB. Interestingly, while swapping the domains from Rsc1 into the Rsc2 protein does not compromise hypersensitivity to DNA damage suggesting they are functionally interchangeable, the BAH domain from Rsc1 confers upon Rsc2 the ability to remodel chromatin at a DNA break. These data demonstrate that, despite the similarity between Rsc1 and Rsc2, the two different isoforms of RSC provide distinct functions in DNA damage responses, and that at least part of the functional specificity is dictated by the BAH domains.

Unique mosaicism of structural chromosomal rearrangement: is chromosome 18 preferentially involved?

NARCIS (Netherlands)

Pater, J.M. de; Smeets, D.F.C.M.; Scheres, J.M.J.C.

2003-01-01

The mentally normal mother of a 4-year-old boy with del(18)(q21.3) syndrome was tested cytogenetically to study the possibility of an inherited structural rearrangement of chromosome 18. She was found to carry an unusual mosaicism involving chromosomes 18 and 21. Two unbalanced cell lines were seen

B chromosomes are associated with redistribution of genetic recombination towards lower recombination chromosomal regions in perennial ryegrass.

Science.gov (United States)

Harper, John; Phillips, Dylan; Thomas, Ann; Gasior, Dagmara; Evans, Caron; Powell, Wayne; King, Julie; King, Ian; Jenkins, Glyn; Armstead, Ian

2018-04-09

Supernumerary 'B' chromosomes are non-essential components of the genome present in a range of plant and animal species-including many grasses. Within diploid and polyploid ryegrass and fescue species, including the forage grass perennial ryegrass (Lolium perenne L.), the presence of B chromosomes has been reported as influencing both chromosome pairing and chiasma frequencies. In this study, the effects of the presence/absence of B chromosomes on genetic recombination has been investigated through generating DArT (Diversity Arrays Technology) marker genetic maps for six perennial ryegrass diploid populations, the pollen parents of which contained either two B or zero B chromosomes. Through genetic and cytological analyses of these progeny and their parents, we have identified that, while overall cytological estimates of chiasma frequencies were significantly lower in pollen mother cells with two B chromosomes as compared with zero B chromosomes, the recombination frequencies within some marker intervals were actually increased, particularly for marker intervals in lower recombination regions of chromosomes, namely pericentromeric regions. Thus, in perennial ryegrass, the presence of two B chromosomes redistributed patterns of meiotic recombination in pollen mother cells in ways which could increase the range of allelic variation available to plant breeders.

Telomere healing following DNA polymerase arrest-induced breakages is likely the main mechanism generating chromosome 4p terminal deletions.

Science.gov (United States)

Hannes, Femke; Van Houdt, Jeroen; Quarrell, Oliver W; Poot, Martin; Hochstenbach, Ron; Fryns, Jean-Pierre; Vermeesch, Joris R

2010-12-01

Constitutional developmental disorders are frequently caused by terminal chromosomal deletions. The mechanisms and/or architectural features that might underlie those chromosome breakages remain largely unexplored. Because telomeres are the vital DNA protein complexes stabilizing linear chromosomes against chromosome degradation, fusion, and incomplete replication, those terminal-deleted chromosomes acquired new telomeres either by telomere healing or by telomere capture. To unravel the mechanisms leading to chromosomal breakage and healing, we sequenced nine chromosome 4p terminal deletion boundaries. A computational analysis of the breakpoint flanking region, including 12 previously published pure terminal breakage sites, was performed in order to identify architectural features that might be involved in this process. All terminal 4p truncations were likely stabilized by telomerase-mediated telomere healing. In the majority of breakpoints multiple genetic elements have a potential to induce secondary structures and an enrichment in replication stalling site motifs were identified. These findings suggest DNA replication stalling-induced chromosome breakage during early development is the first mechanistic step leading toward terminal deletion syndromes. © 2010 Wiley-Liss, Inc.