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ring chromosome

Liangyu Zhang, Simone Köhler, Regina Rillo-Bohn, Abby F Dernburg
During meiosis, each pair of homologous chromosomes typically undergoes at least one crossover (crossover assurance), but these exchanges are strictly limited in number and widely spaced along chromosomes (crossover interference). The molecular basis for this chromosome-wide regulation remains mysterious. A family of meiotic RING finger proteins has been implicated in crossover regulation across eukaryotes. Caenorhabditis elegans expresses four such proteins, of which one (ZHP-3) is known to be required for crossovers...
March 9, 2018: ELife
Seda Çakmaklı, Tufan Çankaya, Semra Gürsoy, Altuğ Koç, Özgür Kırbıyık, Özge A Kılıçarslan, Erdener Özer, Derya Erçal, Özlem G Bozkaya
Ring chromosome 13 is a rare genetic condition with an incidence of 1/58,000 in live births. Major clinical features of patients with ring chromosome 13 include growth and developmental retardation, microcephaly, facial dysmorphism, ambiguous genitalia, anal atresia, eye malformations, retinoblastoma, and hand, foot, and toe abnormalities. The severity of the phenotype depends on the amount of genetic material lost during ring chromosome formation. Here, we report 2 cases with ring chromosome 13 at either end of the phenotypic spectrum...
March 9, 2018: Cytogenetic and Genome Research
Dorian Farache, Laurent Emorine, Laurence Haren, Andreas Merdes
Microtubules are major constituents of the cytoskeleton in all eukaryotic cells. They are essential for chromosome segregation during cell division, for directional intracellular transport and for building specialized cellular structures such as cilia or flagella. Their assembly has to be controlled spatially and temporally. For this, the cell uses multiprotein complexes containing γ-tubulin. γ-Tubulin has been found in two different types of complexes, γ-tubulin small complexes and γ-tubulin ring complexes...
March 2018: Open Biology
Arunika Das, Jeffry Cesario, Anna Maria Hinman, Janet K Jang, Kim S McKim
Bipolar spindle assembly occurs in the absence of centrosomes in the oocytes of most organisms. In the absence of centrosomes in Drosophila oocytes, we have proposed that the kinesin 6 Subito, a MKLP-2 homolog, is required for establishing spindle bipolarity and chromosome biorientation by assembling a robust central spindle during prometaphase I. Although the functions of the conserved motor domains of kinesins is well studied, less is known about the contribution of the poorly conserved N- and C- terminal domains to motor function...
March 7, 2018: G3: Genes—Genomes—Genetics
Ninning Liu, Gheorghe Chistol, Yuanbo Cui, Carlos Bustamante
Multi-subunit ring-shaped ATPases are molecular motors that harness chemical free energy to perform vital mechanical tasks such as polypeptide translocation, DNA unwinding, and chromosome segregation. Previously we reported the intersubunit coordination and stepping behavior of the hexameric ring-shaped ATPase SpoIIIE (Liu et al., 2015). Here we use optical tweezers to characterize the motor's mechanochemistry. Analysis of the motor response to external force at various nucleotide concentrations identifies phosphate release as the likely force-generating step...
March 5, 2018: ELife
Zhi Chen, Wei Zhang, Kaibiao Jiang, Bin Chen, Kun Wang, Lifeng Lao, Canglong Hou, Fei Wang, Caiguo Zhang, Hongxing Shen
Cullins, critical members of the cullin-RING ubiquitin ligases (CRLs), are often aberrantly expressed in different cancers. However, the underlying mechanisms regarding aberrant expression of these cullins and the specific substrates of CRLs in different cancers are mostly unknown. Here, we demonstrate that overexpressed CUL4B in human osteosarcoma cells forms an E3 complex with DNA damage binding protein 1 (DDB1) and DDB1- and CUL4-associated factor 13 (DCAF13). In vitro and in vivo analyses indicated that the CRL4BDCAF13 E3 ligase specifically recognized the tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10) for degradation, and disruption of this E3 ligase resulted in PTEN accumulation...
March 2, 2018: Molecular Therapy. Nucleic Acids
John James Tello Cajiao, Mario Pietro Carante, Mario Antonio Bernal Rodriguez, Francesca Ballarini
It is widely accepted that, in chromosome-aberration induction, the (mis-)rejoining probability of two chromosome fragments depends on their initial distance, r. However, several aspects of these "proximity effects" need to be clarified, also considering that they can vary with radiation quality, cell type and dose. A previous work performed by the BIANCA (BIophysical ANalysis of Cell death and chromosome Aberrations) biophysical model has suggested that, in human lymphocytes and fibroblasts exposed to low-LET radiation, an exponential function of the form exp(-r/r0 ), which is consistent with free-end (confined) diffusion, describes proximity effects better than a Gaussian function...
February 22, 2018: DNA Repair
Qiping Hu, Hongyan Chai, Wei Shu, Peining Li
Background: Constitutional ring chromosomes are rare orphan chromosomal disorders. Ring chromosome syndrome featuring growth retardation and mild to intermediate intellectual disability is likely caused by the dynamic behavior of ring chromosome through cell cycles. Chromosomal and regional specific phenotypes likely result from segmental losses and gains during the ring formation. Although recent applications of genomic copy number and sequencing analyses revealed various ring chromosome structures from an increasing number of case studies, there was no organized effort for compilating and curating cytogenomic and clinical finding for ring chromosomes...
2018: Molecular Cytogenetics
Tatiana V Danilova, Bernd Friebe, Bikram S Gill, Jesse Poland, Eric Jackson
Interspecific or introgressive hybridization is one of the driving forces in plant speciation, producing allopolyploids or diploids with rearranged genomes. The process of karyotype reshaping following homoploid interspecific hybridization has not been studied experimentally. Interspecific hybridization is widely used in plant breeding to increase genetic diversity and introgress new traits. Numerous introgression stocks were developed for hexaploid wheat Triticum aestivum L. (2n = 6x = 42, genome AABBDD). Double monosomic lines, containing one alien chromosome from the tertiary gene pool of wheat and one homoeologous wheat chromosome, represent a simplified model for studying chromosome rearrangements caused by interspecific hybridization...
February 28, 2018: Cytogenetic and Genome Research
Maria Chiara Fontana, Giovanni Marconi, Jelena D Milosevic Feenstra, Eugenio Fonzi, Cristina Papayannidis, Andrea Ghelli Luserna di Rorá, Antonella Padella, Vincenza Solli, Eugenia Franchini, Emanuela Ottaviani, Anna Ferrari, Carmen Baldazzi, Nicoletta Testoni, Ilaria Iacobucci, Simona Soverini, Torsten Haferlach, Viviana Guadagnuolo, Lukas Semerad, Michael Doubek, Michael Steurer, Zdenek Racil, Stefania Paolini, Marco Manfrini, Michele Cavo, Giorgia Simonetti, Robert Kralovics, Giovanni Martinelli
Chromothripsis is a one-step genome-shattering catastrophe resulting from disruption of one or few chromosomes in multiple fragments and consequent random rejoining and repair. This study defines incidence of chromothripsis in 395 newly diagnosed adult acute myeloid leukemia (AML) patients from three institutions, its impact on survival and its genomic background. SNP 6.0 or CytoscanHD Array (Affymetrix® ) were performed on all samples. We detected chromothripsis with a custom algorithm in 26/395 patients...
February 23, 2018: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Alberto L Abbate, Doron Tolomeo, Ingrid Cifola, Marco Severgnini, Antonella Turchiano, Bartolomeo Augello, Gabriella Squeo, Pietro D Addabbo, Debora Traversa, Giulia Daniele, Angelo Lonoce, Mariella Pafundi, Massimo Carella, Orazio Palumbo, Anna Dolnik, Dominique Muehlematter, Jacqueline Schoumans, Nadine Van Roy, Gianluca De Bellis, Giovanni Martinelli, Giuseppe Merla, Lars Bullinger, Claudia Haferlach, Clelia Tiziana Storlazzi
Double minutes (dmin), homogeneously staining regions, and ring chromosomes are vehicles of gene amplification in cancer. The underlying mechanism leading to their formation as well as their structure and function in acute myeloid leukemia (AML) remain mysterious. We combined a range of high-resolution genomic methods to investigate the architecture and expression pattern of amplicons involving chromosome band 8q24 in 23 cases of AML (AML-amp). This revealed that different MYC-dmin architectures can coexist within the same leukemic cell population, indicating a step-wise evolution rather than a single event origin, such as through chromothripsis...
February 22, 2018: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Antonietta Coppola, Deborah Morrogh, Fiona Farrell, Simona Balestrini, Laura Hernandez-Hernandez, S Krithika, Josemir W Sander, Jonathan J Waters, Sanjay M Sisodiya
Chromosomal abnormalities are often identified in people with neurodevelopmental disorders including intellectual disability, autism, and epilepsy. Ring chromosomes, which usually involve gene copy number loss, are formed by fusion of subtelomeric or telomeric chromosomal regions. Some ring chromosomes, including ring 14, 17, and 20, are strongly associated with seizure disorders. We report an individual with a ring chromosome 17, r(17)(p13.3q25.3), with a terminal 17q25.3 deletion and no short arm copy number loss, and with a phenotype characterized by intellectual disability and drug-resistant epilepsy, including a propensity for nonconvulsive status epilepticus...
December 2017: Molecular Syndromology
Shukun Luo, Liang Tong
The cysteine protease separase opens the cohesin ring by cleaving its kleisin subunit and is a pivotal cell cycle factor for the transition from metaphase to anaphase. It is inhibited by forming a complex with the chaperone securin, and in vertebrates, also by the Cdk1-cyclin B1 complex. Separase is activated upon the destruction of securin or cyclin B1 by the proteasome, after ubiquitination by the anaphase-promoting complex/cyclosome (APC/C). Here we review recent structures of the active protease segment of Chaetomium thermophilum separase in complex with a substrate-mimic inhibitor and full-length Saccharomyces cerevisiae and Caenorhabditis elegans separase in complex with securin...
February 13, 2018: Current Opinion in Structural Biology
Yogitha Thattikota, Sylvain Tollis, Roger Palou, Justine Vinet, Mike Tyers, Damien D'Amours
The morphological transformation of amorphous chromatin into distinct chromosomes is a hallmark of mitosis. To achieve this, chromatin must be compacted and remodeled by a ring-shaped enzyme complex known as condensin. However, the mechanistic basis underpinning condensin's role in chromosome remodeling has remained elusive. Here we show that condensin has a strong tendency to trap itself in its own reaction product during chromatin compaction and yet is capable of interacting with chromatin in a highly dynamic manner in vivo...
February 15, 2018: Molecular Cell
Nan Liu, Tong Tong, Yue Chen, Yanling Chen, Chunquan Cai
OBJECTIVE To explore the origin and morphological features of small supernumerary marker chromosomes (sSMCs) in Turner syndrome. METHODS For 5 cases of Turner syndrome with a sSMC identified by conventional G-banding, dual-color fluorescence in situ hybridization (FISH) was applied to explore their origin and morphological features. RESULTS Among the 5 cases, 3 have derived from the X chromosome, which included 2 ring chromosomes and 1 centric minute. For the 2 sSMCs derived from the Y chromosome, 1 was ring or isodicentric chromosome, while the other was an isodicentric chromosome...
February 10, 2018: Zhonghua Yi Xue Yi Chuan Xue za Zhi, Zhonghua Yixue Yichuanxue Zazhi, Chinese Journal of Medical Genetics
A B Gago-Veiga, R Toledano, I García-Morales, M A Pérez-Jiménez, J Bernar, A Gil-Nagel
BACKGROUND: Ring chromosome 20 (R20) syndrome is a chromosomal disorder characterized mainly by drug-resistant frontal lobe seizures, recurrent nonconvulsive status epilepticus (NCSE), and typical EEG features. The aim of this study was to investigate if this triad is common and specific to all patients with R20. METHODS: In this cross-sectional study (from 2000 to 2011), we selected patients who fulfilled at least two out of three criteria: drug-resistant frontal lobe seizures, recurrent NCSE, and characteristic electroencephalography (EEG) features...
February 2, 2018: Epilepsy & Behavior: E&B
Fayza M Aly, Ahmed M Kotb, Seddik Hammad
Todays, bioactive compounds extracted from Spirulina platensis have been intensively studied for their therapeutical values. Therefore, in the present study, we aimed to evaluate the effects of S. platensis extract on DNA damage and chromosomal aberrations induced by cadmium in rats. Four groups of male albino rats (n = 7 rats) were used. The first group served as a control group and received distilled water. The second group was exposed intraperitoneally to cadmium chloride (CdCl2) (3.5 mg/kg body weight dissolved in 2 ml distilled water)...
February 3, 2018: Environmental Science and Pollution Research International
Katsuya Yamamoto, Shinichiro Kawamoto, Keiji Kurata, Akihito Kitao, Yu Mizutani, Hiroya Ichikawa, Kimikazu Yakushijin, Kazuyoshi Kajimoto, Yoshitake Hayashi, Hiroshi Matsuoka, Hironobu Minami
Oncogene amplification is uncommon in acute myeloid leukemia (AML). Cytogenetically, it is primarily found as double minute chromosomes (dmin) or homogeneously staining regions (hsr). A 62-year-old woman was admitted to our hospital because of anemia and thrombocytopenia. Her bone marrow was hypercellular with 78.6% myeloperoxidase- positive blasts. Some had micronuclei. The patient was diagnosed with AML M2 and remains in complete remission (CR) after induction therapy. G-banding at diagnosis showed 51,XX,t(11;16)(q13;p11...
January 24, 2018: Cytogenetic and Genome Research
Nehir Kurtas, Filippo Arrigoni, Edoardo Errichiello, Claudio Zucca, Cristina Maghini, Maria Grazia D'Angelo, Silvana Beri, Roberto Giorda, Sara Bertuzzo, Massimo Delledonne, Luciano Xumerle, Marzia Rossato, Orsetta Zuffardi, Maria Clara Bonaglia
INTRODUCTION: Phelan-McDermid syndrome (PMS) is caused by SHANK3 haploinsufficiency. Its wide phenotypic variation is attributed partly to the type and size of 22q13 genomic lesion (deletion, unbalanced translocation, ring chromosome), partly to additional undefined factors. We investigated a child with severe global neurodevelopmental delay (NDD) compatible with her distal 22q13 deletion, complicated by bilateral perisylvian polymicrogyria (BPP) and urticarial rashes, unreported in PMS...
January 29, 2018: Journal of Medical Genetics
T Gazoni, C F B Haddad, H Narimatsu, D C Cabral-de-Mello, M L Lyra, P P Parise-Maltempi
Heteromorphic sex chromosomes are common in eukaryotes and largely ubiquitous in birds and mammals. The largest number of multiple sex chromosomes in vertebrates known today is found in the monotreme platypus (Ornithorhynchus anatinus, 2n = 52) which exhibits precisely 10 sex chromosomes. Interestingly, fish, amphibians, and reptiles have sex determination mechanisms that do or do not involve morphologically differentiated sex chromosomes. Relatively few amphibian species carry heteromorphic sex chromosomes, and when present, they are frequently represented by only one pair, either XX:XY or ZZ:ZW types...
January 26, 2018: Chromosoma
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