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Chromosoma

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https://www.readbyqxmd.com/read/28688040/identification-of-all-homoeologous-chromosomes-of-newly-synthetic-allotetraploid-cucumis-%C3%A3-hytivus-and-its-wild-parent-reveals-stable-subgenome-structure
#1
Yunzhu Wang, Qinzheng Zhao, Xiaodong Qin, Shuqiong Yang, Ziang Li, Ji Li, Qunfeng Lou, Jinfeng Chen
Allopolyploidy and homoeologous recombination are two important processes in reshaping genomes and generating evolutionary novelties. Newly formed allopolyploids usually display chromosomal perturbations as a result of pairing errors at meiosis. To understand mechanisms of stabilization of allopolyploid species derived from distant chromosome bases, we investigated mitotic stability of a synthetic Cucumis allotetraploid species in relation to meiosis chromosome behavior. The Cucumis × hytivus is an allotetraploid synthesized from interspecific hybridization between cucumber (Cucumis sativus, 2n = 14) and its wild relative Cucumis hystrix (2n = 24) followed by spontaneous chromosome doubling...
July 7, 2017: Chromosoma
https://www.readbyqxmd.com/read/28688039/using-human-artificial-chromosomes-to-study-centromere-assembly-and-function
#2
REVIEW
Oscar Molina, Natalay Kouprina, Hiroshi Masumoto, Vladimir Larionov, William C Earnshaw
Centromeres are the site of assembly of the kinetochore, which directs chromosome segregation during cell division. Active centromeres are characterized by the presence of nucleosomes containing CENP-A and a specific chromatin environment that resembles that of active genes. Recent work using human artificial chromosomes (HAC) sheds light on the fine balance of different histone post-translational modifications and transcription that exists at centromeres for kinetochore assembly and maintenance. Here, we review the use of HAC technology to understand centromere assembly and function...
July 7, 2017: Chromosoma
https://www.readbyqxmd.com/read/28688038/dadd1-and-dxnp-prevent-genome-instability-by-maintaining-hp1a-localization-at-drosophila-telomeres
#3
Joselyn Chavez, Juan Manuel Murillo-Maldonado, Vanessa Bahena, Ana Karina Cruz, América Castañeda-Sortibrán, Rosario Rodriguez-Arnaiz, Mario Zurita, Viviana Valadez-Graham
Telomeres are important contributors to genome stability, as they prevent linear chromosome end degradation and contribute to the avoidance of telomeric fusions. An important component of the telomeres is the heterochromatin protein 1a (HP1a). Mutations in Su(var)205, the gene encoding HP1a in Drosophila, result in telomeric fusions, retrotransposon regulation loss and larger telomeres, leading to chromosome instability. Previously, it was found that several proteins physically interact with HP1a, including dXNP and dAdd1 (orthologues to the mammalian ATRX gene)...
July 7, 2017: Chromosoma
https://www.readbyqxmd.com/read/28593374/chromatin-loops-and-causality-loops-the-influence-of-rna-upon-spatial-nuclear-architecture
#4
REVIEW
Iain A Sawyer, Miroslav Dundr
An intrinsic and essential trait exhibited by cells is the properly coordinated and integrated regulation of an astoundingly large number of simultaneous molecular decisions and reactions to maintain biochemical homeostasis. This is especially true inside the cell nucleus, where the recognition of DNA and RNA by a vast range of nucleic acid-interacting proteins organizes gene expression patterns. However, this dynamic system is not regulated by simple "on" or "off" signals. Instead, transcription factor and RNA polymerase recruitment to DNA are influenced by the local chromatin and epigenetic environment, a gene's relative position within the nucleus and the action of noncoding RNAs...
June 7, 2017: Chromosoma
https://www.readbyqxmd.com/read/28527011/the-prdm9-krab-domain-is-required-for-meiosis-and-involved-in-protein-interactions
#5
Yukiko Imai, Frédéric Baudat, Miguel Taillepierre, Marcello Stanzione, Attila Toth, Bernard de Massy
PR domain-containing protein 9 (PRDM9) is a major regulator of the localization of meiotic recombination hotspots in the human and mouse genomes. This role involves its DNA-binding domain, which is composed of a tandem array of zinc fingers, and PRDM9-dependent trimethylation of histone H3 at lysine 4. PRDM9 is a member of the PRDM family of transcription regulators, but unlike other family members, it contains a Krüppel-associated box (KRAB)-related domain that is predicted to be a potential protein interaction domain...
May 19, 2017: Chromosoma
https://www.readbyqxmd.com/read/27909815/homoeologous-recombination-in-the-presence-of-ph1-gene-in-wheat
#6
Dal-Hoe Koo, Wenxuan Liu, Bernd Friebe, Bikram S Gill
A crossover (CO) and its cytological signature, the chiasma, are major features of eukaryotic meiosis. The formation of at least one CO/chiasma between homologous chromosome pairs is essential for accurate chromosome segregation at the first meiotic division and genetic recombination. Polyploid organisms with multiple sets of homoeologous chromosomes have evolved additional mechanisms for the regulation of CO/chiasma. In hexaploid wheat (2n = 6× = 42), this is accomplished by pairing homoeologous (Ph) genes, with Ph1 having the strongest effect on suppressing homoeologous recombination and homoeologous COs...
August 2017: Chromosoma
https://www.readbyqxmd.com/read/27882407/a-novel-system-for-correcting-large-scale-chromosomal-aberrations-ring-chromosome-correction-via-reprogramming-into-induced-pluripotent-stem-cell-ipsc
#7
REVIEW
Taehyun Kim, Kathleen Plona, Anthony Wynshaw-Boris
Approximately 1 in 500 newborns are born with chromosomal abnormalities that include trisomies, translocations, large deletions, and duplications. There is currently no therapeutic approach for correcting such chromosomal aberrations in vivo or in vitro. When we attempted to produce induced pluripotent stem cell (iPSC) models from patient-derived fibroblasts that contained ring chromosomes, we found that the ring chromosomes were eliminated and replaced by duplicated normal copies of chromosomes through a mechanism of uniparental isodisomy (Bershteyn et al...
August 2017: Chromosoma
https://www.readbyqxmd.com/read/27858158/structure-of-centromere-chromatin-from-nucleosome-to-chromosomal-architecture
#8
REVIEW
Thomas Schalch, Florian A Steiner
The centromere is essential for the segregation of chromosomes, as it serves as attachment site for microtubules to mediate chromosome segregation during mitosis and meiosis. In most organisms, the centromere is restricted to one chromosomal region that appears as primary constriction on the condensed chromosome and is partitioned into two chromatin domains: The centromere core is characterized by the centromere-specific histone H3 variant CENP-A (also called cenH3) and is required for specifying the centromere and for building the kinetochore complex during mitosis...
August 2017: Chromosoma
https://www.readbyqxmd.com/read/27834006/centromere-repositioning-explains-fundamental-number-variability-in-the-new-world-monkey-genus-saimiri
#9
Giorgia Chiatante, Oronzo Capozzi, Marta Svartman, Polina Perelman, Lucy Centrone, Svetlana S Romanenko, Takafumi Ishida, Mirela Valeri, Melody E Roelke-Parker, Roscoe Stanyon
Cytogenetics has historically played a key role in research on squirrel monkey (genus Saimiri) evolutionary biology. Squirrel monkeys have a diploid number of 2n = 44, but vary in fundamental number (FN). Apparently, differences in FN have phylogenetic implications and are correlated with geographic regions. A number of hypothetical mechanisms were proposed to explain difference in FN: translocations, heterochromatin, or, most commonly, pericentric inversions. Recently, an additional mechanism, centromere repositioning, was discovered, which can alter chromosome morphology and FN...
August 2017: Chromosoma
https://www.readbyqxmd.com/read/27534416/the-effect-of-the-lamin-a-and-its-mutants-on-nuclear-structure-cell-proliferation-protein-stability-and-mobility-in-embryonic-cells
#10
Katarzyna Piekarowicz, Magdalena Machowska, Ewelina Dratkiewicz, Daria Lorek, Agnieszka Madej-Pilarczyk, Ryszard Rzepecki
LMNA gene encodes for nuclear intermediate filament proteins lamin A/C. Mutations in this gene lead to a spectrum of genetic disorders, collectively referred to as laminopathies. Lamin A/C are widely expressed in most differentiated somatic cells but not in early embryos and some undifferentiated cells. To investigate the role of lamin A/C in cell phenotype maintenance and differentiation, which could be a determinant of the pathogenesis of laminopathies, we examined the role played by exogenous lamin A and its mutants in differentiated cell lines (HeLa, NHDF) and less-differentiated HEK 293 cells...
August 2017: Chromosoma
https://www.readbyqxmd.com/read/27522227/satellite-dna-content-illuminates-the-ancestry-of-a-supernumerary-b-chromosome
#11
Francisco J Ruiz-Ruano, Josefa Cabrero, María Dolores López-León, Juan Pedro M Camacho
B chromosomes are supernumerary genomic elements most likely derived from the standard (A) chromosomes, whose dispensability has freed their DNA sequences to evolve fast, thus making it difficult to uncover their ancestry. Here, we show the ancestry of a B chromosome in the grasshopper Eumigus monticola by means of the high-throughput analysis of the satellitome, i.e., the whole collection of satellite DNA (satDNA). The satellitome found in this species consists of 27 satDNA families, with monomer length between 5 and 325 nt and A + T content between 42...
August 2017: Chromosoma
https://www.readbyqxmd.com/read/27354041/aurora-a-mcak-and-kif18b-promote-eg5-independent-spindle-formation
#12
Roy G H P van Heesbeen, Jonne A Raaijmakers, Marvin E Tanenbaum, Vincentius A Halim, Daphne Lelieveld, Cor Lieftink, Albert J R Heck, David A Egan, René H Medema
Inhibition of the microtubule (MT) motor protein Eg5 results in a mitotic arrest due to the formation of monopolar spindles, making Eg5 an attractive target for anti-cancer therapies. However, Eg5-independent pathways for bipolar spindle formation exist, which might promote resistance to treatment with Eg5 inhibitors. To identify essential components for Eg5-independent bipolar spindle formation, we performed a genome-wide siRNA screen in Eg5-independent cells (EICs). We find that the kinase Aurora A and two kinesins, MCAK and Kif18b, are essential for bipolar spindle assembly in EICs and in cells with reduced Eg5 activity...
August 2017: Chromosoma
https://www.readbyqxmd.com/read/27325172/a-replication-time-controlling-sequence-element-in-schizosaccharomyces-pombe
#13
Vishnu P Tripathi, Dharani D Dubey
Eukaryotic replication origins are highly variable in their activity and replication timing. The nature and role of cis-acting regulatory sequences that control chromosomal replication timing is not well defined. In the fission yeast, Schizosaccharomyces pombe, a 200-bp late-replication-enforcing element (LRE), has been shown to enforce late replication of ARS elements in plasmids. Here, we show that a short (133-bp) fragment of the LRE (shLRE) is required for causing late replication of adjoining origins in its native as well as in an ectopic early-replicating chromosomal location...
August 2017: Chromosoma
https://www.readbyqxmd.com/read/28213686/the-iswi-remodeler-in-plants-protein-complexes-biochemical-functions-and-developmental-roles
#14
REVIEW
Dongjie Li, Jie Liu, Wu Liu, Guang Li, Zhongnan Yang, Peng Qin, Lin Xu
Imitation Switch (ISWI) is a member of the ATP-dependent chromatin remodeling factor family, whose members move or restructure nucleosomes using energy derived from ATP hydrolysis. ISWI proteins are conserved in eukaryotes and usually form complexes with DDT (DNA-binding homeobox and different transcription factors)-domain proteins. Here, we review recent research on ISWI in the model plant Arabidopsis thaliana (AtISWI). AtISWI forms complexes with AtDDT-domain proteins, many of which have domain structures that differ from those of DDT-domain proteins in yeast and animals...
June 2017: Chromosoma
https://www.readbyqxmd.com/read/27837282/the-chromosomal-basis-of-meiotic-acentrosomal-spindle-assembly-and-function-in-oocytes
#15
REVIEW
Sarah J Radford, Alexandra L Nguyen, Karen Schindler, Kim S McKim
Several aspects of meiosis are impacted by the absence of centrosomes in oocytes. Here, we review four aspects of meiosis I that are significantly affected by the absence of centrosomes in oocyte spindles. One, microtubules tend to assemble around the chromosomes. Two, the organization of these microtubules into a bipolar spindle is directed by the chromosomes. Three, chromosome bi-orientation and attachment to microtubules from the correct pole require modification of the mechanisms used in mitotic cells. Four, chromosome movement to the poles at anaphase cannot rely on polar anchoring of spindle microtubules by centrosomes...
June 2017: Chromosoma
https://www.readbyqxmd.com/read/27638401/investigating-somatic-aneuploidy-in-the-brain-why-we-need-a-new-model
#16
REVIEW
Jimi L Rosenkrantz, Lucia Carbone
The steady occurrence of DNA mutations is a key source for evolution, generating the genomic variation in the population upon which natural selection acts. Mutations driving evolution have to occur in the oocytes and sperm in order to be transmitted to the next generation. Through similar mechanisms, mutations also accumulate in somatic cells (e.g., skin cells, neurons, lymphocytes) during development and adult life. The concept that somatic cells can collect new mutations with time suggests that we are a mosaic of cells with different genomic compositions...
June 2017: Chromosoma
https://www.readbyqxmd.com/read/27300555/transvection-in-drosophila-trans-interaction-between-yellow-enhancers-and-promoter-is-strongly-suppressed-by-a-cis-promoter-only-in-certain-genomic-regions
#17
Oksana Kravchuk, Maria Kim, Pavel Klepikov, Alexander Parshikov, Pavel Georgiev, Mikhail Savitsky
Transvection is a phenomenon of interallelic communication whereby enhancers of one allele can activate a promoter located on the homologous chromosome. It has been shown for many independent genes that enhancers preferentially act on the cis-linked promoter, but deletion of this promoter allows the enhancers to act in trans. Here, we tested whether this cis-preference in the enhancer-promoter interaction could be reconstituted outside of the natural position of a gene. The yellow gene was chosen as a model system...
June 2017: Chromosoma
https://www.readbyqxmd.com/read/27277787/coordination-of-the-recruitment-of-the-fancd2-and-palb2-fanconi-anemia-proteins-by-an-ubiquitin-signaling-network
#18
Gregory Bick, Fan Zhang, A Ruhikanta Meetei, Paul R Andreassen
Fanconi anemia (FA) is a chromosome instability syndrome and the 20 identified FA proteins are organized into two main arms which are thought to function at distinct steps in the repair of DNA interstrand crosslinks (ICLs). These two arms include the upstream FA pathway, which culminates in the monoubiquitination of FANCD2 and FANCI, and downstream breast cancer (BRCA)-associated proteins that interact in protein complexes. How, and whether, these two groups of FA proteins are integrated is unclear. Here, we show that FANCD2 and PALB2, as indicators of the upstream and downstream arms, respectively, colocalize independently of each other in response to DNA damage induced by mitomycin C (MMC)...
June 2017: Chromosoma
https://www.readbyqxmd.com/read/27165042/the-enigmatic-meiotic-dense-body-and-its-newly-discovered-component-scml1-are-dispensable-for-fertility-and-gametogenesis-in-mice
#19
Frantzeskos Papanikos, Katrin Daniel, Angelique Goercharn-Ramlal, Ji-Feng Fei, Thomas Kurth, Lukasz Wojtasz, Ihsan Dereli, Jun Fu, Josef Penninger, Bianca Habermann, Azim Surani, A Francis Stewart, Attila Toth
Meiosis is a critical phase in the life cycle of sexually reproducing organisms. Chromosome numbers are halved during meiosis, which requires meiosis-specific modification of chromosome behaviour. Furthermore, suppression of transposons is particularly important during meiosis to allow the transmission of undamaged genomic information between generations. Correspondingly, specialized genome defence mechanisms and nuclear structures characterize the germ line during meiosis. Survival of mammalian spermatocytes requires that the sex chromosomes form a distinct silenced chromatin domain, called the sex body...
June 2017: Chromosoma
https://www.readbyqxmd.com/read/27153834/chromosome-identification-for-the-carnivorous-plant-genlisea-margaretae
#20
Trung D Tran, Hana Šimková, Renate Schmidt, Jaroslav Doležel, Ingo Schubert, Jörg Fuchs
Genlisea margaretae, subgenus Genlisea, section Recurvatae (184 Mbp/1C), belongs to a plant genus with a 25-fold genome size difference and an extreme genome plasticity. Its 19 chromosome pairs could be distinguished individually by an approach combining optimized probe pooling and consecutive rounds of multicolor fluorescence in situ hybridization (mcFISH) with bacterial artificial chromosomes (BACs) selected for repeat-free inserts. Fifty-one BACs were assigned to 18 chromosome pairs. They provide a tool for future assignment of genomic sequence contigs to distinct chromosomes as well as for identification of homeologous chromosome regions in other species of the carnivorous Lentibulariaceae family, and potentially of chromosome rearrangements, in cases where more than one BAC per chromosome pair was identified...
June 2017: Chromosoma
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