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Chromosoma

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https://read.qxmd.com/read/30739171/immediate-visualization-of-recombination-events-and-chromosome-segregation-defects-in-fission-yeast-meiosis
#1
Dmitriy Li, Marianne Roca, Raif Yuecel, Alexander Lorenz
Schizosaccharomyces pombe, also known as fission yeast, is an established model for studying chromosome biological processes. Over the years, research employing fission yeast has made important contributions to our knowledge about chromosome segregation during meiosis, as well as meiotic recombination and its regulation. Quantification of meiotic recombination frequency is not a straightforward undertaking, either requiring viable progeny for a genetic plating assay, or relying on laborious Southern blot analysis of recombination intermediates...
February 9, 2019: Chromosoma
https://read.qxmd.com/read/30719566/maternal-regulation-of-chromosomal-imprinting-in-animals
#2
REVIEW
Prim B Singh, Victor V Shloma, Stepan N Belyakin
Chromosomal imprinting requires an epigenetic system that "imprints" one of the two parental chromosomes such that it results in a heritable (cell-to-cell) change in behavior of the "imprinted" chromosome. Imprinting takes place when the parental genomes are separate, which occurs during gamete formation in the respective germ-lines and post-fertilization during the period when the parental pro-nuclei lie separately within the ooplasm of the zygote. In the mouse, chromosomal imprinting is regulated by germ-line specific DNA methylation...
February 5, 2019: Chromosoma
https://read.qxmd.com/read/30617552/gene-expression-changes-elicited-by-a-parasitic-b-chromosome-in-the-grasshopper-eyprepocnemis-plorans-are-consistent-with-its-phenotypic-effects
#3
Beatriz Navarro-Domínguez, María Martín-Peciña, Francisco J Ruiz-Ruano, Josefa Cabrero, José María Corral, María Dolores López-León, Timothy F Sharbel, Juan Pedro M Camacho
Parasitism evokes adaptive physiological changes in the host, many of which take place through gene expression changes. This response can be more or less local, depending on the organ or tissue affected by the parasite, or else systemic when the parasite affects the entire host body. The most extreme of the latter cases is intragenomic parasitism, where the parasite is present in all host nuclei as any other genomic element. Here, we show the molecular crosstalk between a parasitic chromosome (also named B chromosome) and the host genome, manifested through gene expression changes...
January 7, 2019: Chromosoma
https://read.qxmd.com/read/30612150/a-new-role-for-drosophila-aurora-a-in-maintaining-chromosome-integrity
#4
Chiara Merigliano, Elisa Mascolo, Anthony Cesta, Isabella Saggio, Fiammetta Vernì
Aurora-A is a conserved mitotic kinase overexpressed in many types of cancer. Growing evidence shows that Aurora-A plays a crucial role in DNA damage response (DDR) although this aspect has been less characterized. We isolated a new aur-A mutation, named aur-A949 , in Drosophila, and we showed that it causes chromosome aberrations (CABs). In addition, aur-A949 mutants were sensitive to X-ray treatment and showed impaired γ-H2Av foci dissolution kinetics. To identify the pathway in which Aur-A works, we conducted an epistasis analysis by evaluating CAB frequencies in double mutants carrying aur-A949 mutation combined to mutations in genes related to DNA damage response (DDR)...
January 5, 2019: Chromosoma
https://read.qxmd.com/read/30607510/molecular-structure-of-human-synaptonemal-complex-protein-syce1
#5
Orla M Dunne, Owen R Davies
The reduction in chromosome number during meiosis is essential for the production of haploid germ cells and thereby fertility. To achieve this, homologous chromosomes are first synapsed together by a protein assembly, the synaptonemal complex (SC), which permits genetic exchange by crossing over and the subsequent accurate segregation of homologues. The mammalian SC is formed of a zipper-like array of SYCP1 molecules that bind together homologous chromosomes through self-assembly in the midline that is structurally supported by the central element...
January 3, 2019: Chromosoma
https://read.qxmd.com/read/30483879/out-of-position-telomeres-in-meiotic-leptotene-appear-responsible-for-chiasmate-pairing-in-an-inversion-heterozygote-in-wheat-triticum-aestivum-l
#6
Katerina Pernickova, Gabriella Linc, Eszter Gaal, David Kopecky, Olga Samajova, Adam J Lukaszewski
Chromosome pairing in meiosis usually starts in the vicinity of the telomere attachment to the nuclear membrane and congregation of telomeres in the leptotene bouquet is believed responsible for bringing homologue pairs together. In a heterozygote for an inversion of a rye (Secale cereale L.) chromosome arm in wheat, a distal segment of the normal homologue is capable of chiasmate pairing with its counterpart in the inverted arm, located near the centromere. Using 3D imaging confocal microscopy, we observed that some telomeres failed to be incorporated into the bouquet and occupied various positions throughout the entire volume of the nucleus, including the centromere pole...
November 27, 2018: Chromosoma
https://read.qxmd.com/read/30291421/heterochromatin-restricts-the-mobility-of-nuclear-bodies
#7
Eugene A Arifulin, Dmitry V Sorokin, Anna V Tvorogova, Margarita A Kurnaeva, Yana R Musinova, Oxana A Zhironkina, Sergey A Golyshev, Sergey S Abramchuk, Yegor S Vassetzky, Eugene V Sheval
Nuclear bodies are relatively immobile organelles. Here, we investigated the mechanisms underlying their movement using experimentally induced interphase prenucleolar bodies (iPNBs). Most iPNBs demonstrated constrained diffusion, exhibiting infrequent fusions with other iPNBs and nucleoli. Fusion events were actin-independent and appeared to be the consequence of stochastic collisions between iPNBs. Most iPNBs were surrounded by condensed chromatin, while fusing iPNBs were usually found in a single heterochromatin-delimited compartment ("cage")...
December 2018: Chromosoma
https://read.qxmd.com/read/30276463/transcriptional-repression-of-cdc6-and-sld2-during-meiosis-is-associated-with-production-of-short-heterogeneous-rna-isoforms
#8
David V Phizicky, Stephen P Bell
Execution of the meiotic and mitotic cell division programs requires distinct gene expression patterns. Unlike mitotic cells, meiotic cells reduce ploidy by following one round of DNA replication with two rounds of chromosome segregation (meiosis I and meiosis II). However, the mechanisms by which cells prevent DNA replication between meiosis I and meiosis II are not fully understood. Here, we show that transcriptional repression of two essential DNA replication genes, CDC6 and SLD2, is associated with production of shorter meiosis-specific RNAs containing the 3' end of both genes...
December 2018: Chromosoma
https://read.qxmd.com/read/30242479/chromosome-painting-in-meiosis-reveals-pairing-of-specific-chromosomes-in-polyploid-solanum-species
#9
Li He, Guilherme T Braz, Giovana A Torres, Jiming Jiang
Analysis of chromosome pairing has been an important tool to assess the genetic similarity of homologous and homoeologous chromosomes in polyploids. However, it is technically challenging to monitor the pairing of specific chromosomes in polyploid species, especially for plant species with a large number of small chromosomes. We developed oligonucleotide-based painting probes for four different potato chromosomes. We demonstrate that these probes are robust enough to monitor a single chromosome throughout the prophase I of meiosis in polyploid Solanum species...
December 2018: Chromosoma
https://read.qxmd.com/read/30120539/phenotypic-characterization-of-diamond-dind-a-drosophila-gene-required-for-multiple-aspects-of-cell-division
#10
Lucia Graziadio, Valeria Palumbo, Francesca Cipressa, Byron C Williams, Giovanni Cenci, Maurizio Gatti, Michael L Goldberg, Silvia Bonaccorsi
Many genes are required for the assembly of the mitotic apparatus and for proper chromosome behavior during mitosis and meiosis. A fruitful approach to elucidate the mechanisms underlying cell division is the accurate phenotypic characterization of mutations in these genes. Here, we report the identification and characterization of diamond (dind), an essential Drosophila gene required both for mitosis of larval brain cells and for male meiosis. Larvae homozygous for any of the five EMS-induced mutations die in the third-instar stage and exhibit multiple mitotic defects...
December 2018: Chromosoma
https://read.qxmd.com/read/30030602/new-slbo-gal4-driver-lines-for-the-analysis-of-border-cell-migration-during-drosophila-oogenesis
#11
Anna A Ogienko, Lyubov A Yarinich, Elena V Fedorova, Mikhail O Lebedev, Evgeniya N Andreyeva, Alexey V Pindyurin, Elina M Baricheva
Border cell (BC) migration during Drosophila oogenesis is an excellent model for the analysis of the migratory and invasive cell behavior. Most studies on BC migration have exploited a slbo-Gal4 driver to regulate gene expression in these cells or to mark them. Here, we report that the slbo-Gal4 transgene present in the line #6458 from the Bloomington Stock Center is inserted within chickadee (chic), a gene encoding the actin-binding protein Profilin, which promotes actin polymerization and is known to be involved in cell migration...
December 2018: Chromosoma
https://read.qxmd.com/read/29968190/chmp4c-is-required-for-stable-kinetochore-microtubule-attachments
#12
Eleni Petsalaki, Maria Dandoulaki, George Zachos
Formation of stable kinetochore-microtubule attachments is essential for accurate chromosome segregation in human cells and depends on the NDC80 complex. We recently showed that Chmp4c, an endosomal sorting complex required for transport protein involved in membrane remodelling, localises to prometaphase kinetochores and promotes cold-stable kinetochore microtubules, faithful chromosome alignment and segregation. In the present study, we show that Chmp4c associates with the NDC80 components Hec1 and Nuf2 and is required for optimal NDC80 stability and Hec1-Nuf2 localisation to kinetochores in prometaphase...
December 2018: Chromosoma
https://read.qxmd.com/read/29948142/a-streamlined-cohesin-apparatus-is-sufficient-for-mitosis-and-meiosis-in-the-protist-tetrahymena
#13
Emine I Ali, Josef Loidl, Rachel A Howard-Till
In order to understand its diverse functions, we have studied cohesin in the evolutionarily distant ciliate model organism Tetrahymena thermophila. In this binucleate cell, the heritable germline genome is maintained separately from the transcriptionally active somatic genome. In a previous study, we showed that a minimal cohesin complex in Tetrahymena consisted of homologs of Smc1, Smc3, and Rec8, which are present only in the germline nucleus, where they are needed for normal chromosome segregation as well as meiotic DNA repair...
December 2018: Chromosoma
https://read.qxmd.com/read/30448925/patterns-of-microchromosome-organization-remain-highly-conserved-throughout-avian-evolution
#14
Rebecca E O'Connor, Lucas Kiazim, Ben Skinner, Gothami Fonseka, Sunitha Joseph, Rebecca Jennings, Denis M Larkin, Darren K Griffin
The structure and organization of a species genome at a karyotypic level, and in interphase nuclei, have broad functional significance. Although regular sized chromosomes are studied extensively in this regard, microchromosomes, which are present in many terrestrial vertebrates, remain poorly explored. Birds have more cytologically indistinguishable microchromosomes (~ 30 pairs) than other vertebrates; however, the degree to which genome organization patterns at a karyotypic and interphase level differ between species is unknown...
November 17, 2018: Chromosoma
https://read.qxmd.com/read/30357462/genomic-3d-compartments-emerge-from-unfolding-mitotic-chromosomes
#15
Rajendra Kumar, Ludvig Lizana, Per Stenberg
The 3D organisation of the genome in interphase cells is not a randomly folded polymer. Rather, experiments show that chromosomes arrange into a network of 3D compartments that correlate with biological processes, such as transcription, chromatin modifications and protein binding. However, these compartments do not exist during cell division when the DNA is condensed, and it is unclear how and when they emerge. In this paper, we focus on the early stages after cell division as the chromosomes start to decondense...
October 24, 2018: Chromosoma
https://read.qxmd.com/read/30175387/use-of-3d-imaging-for-providing-insights-into-high-order-structure-of-mitotic-chromosomes
#16
REVIEW
Mohammed Yusuf, Kohei Kaneyoshi, Kiichi Fukui, Ian Robinson
The high-order structure of metaphase chromosomes remains still under investigation, especially the 30-nm structure that is still controversial. Advanced 3D imaging has provided useful information for our understanding of this detailed structure. It is evident that new technologies together with improved sample preparations and image analyses should be adequately combined. This mini review highlights 3D imaging used for chromosome analysis so far with future imaging directions also highlighted.
September 3, 2018: Chromosoma
https://read.qxmd.com/read/29666907/three-dimensional-analysis-of-nuclear-heterochromatin-distribution-during-early-development-in-the-rabbit
#17
Amélie Bonnet-Garnier, Kiên Kiêu, Tiphaine Aguirre-Lavin, Krisztina Tar, Pierre Flores, Zichuan Liu, Nathalie Peynot, Martine Chebrout, András Dinnyés, Véronique Duranthon, Nathalie Beaujean
Changes to the spatial organization of specific chromatin domains such as constitutive heterochromatin have been studied extensively in somatic cells. During early embryonic development, drastic epigenetic reprogramming of both the maternal and paternal genomes, followed by chromatin remodeling at the time of embryonic genome activation (EGA), have been observed in the mouse. Very few studies have been performed in other mammalian species (human, bovine, or rabbit) and the data are far from complete. During this work, we studied the three-dimensional organization of pericentromeric regions during the preimplantation period in the rabbit using specific techniques (3D-FISH) and tools (semi-automated image analysis)...
September 2018: Chromosoma
https://read.qxmd.com/read/29656322/p190rhogap-prevents-mitotic-spindle-fragmentation-and-is-required-to-activate-aurora-a-kinase-at-acentriolar-poles
#18
Arkadi Manukyan, Lilit Sargsyan, Sarah J Parsons, P Todd Stukenberg
Assembly of the mitotic spindle is essential for proper chromosome segregation during mitosis. Maintenance of spindle poles requires precise regulation of kinesin- and dynein-generated forces, and improper regulation of these forces disrupts pole integrity leading to pole fragmentation. The formation and function of the mitotic spindle are regulated by many proteins, including Aurora A kinase and the motor proteins Kif2a and Eg5. Here, we characterize a surprising role for the RhoA GTPase-activating protein, p190RhoGAP, in regulating the mitotic spindle...
September 2018: Chromosoma
https://read.qxmd.com/read/29610944/imaging-the-dynamics-of-transcription-loops-in-living-chromosomes
#19
Garry T Morgan
When in the lampbrush configuration, chromosomes display thousands of visible DNA loops that are transcribed at exceptionally high rates by RNA polymerase II (pol II). These transcription loops provide unique opportunities to investigate not only the detailed architecture of pol II transcription sites but also the structural dynamics of chromosome looping, which is receiving fresh attention as the organizational principle underpinning the higher-order structure of all chromosome states. The approach described here allows for extended imaging of individual transcription loops and transcription units under conditions in which loop RNA synthesis continues...
September 2018: Chromosoma
https://read.qxmd.com/read/29594515/the-response-to-dna-damage-in-heterochromatin-domains
#20
REVIEW
Anna Fortuny, Sophie E Polo
Eukaryotic genomes are organized into chromatin, divided into structurally and functionally distinct euchromatin and heterochromatin compartments. The high level of compaction and the abundance of repeated sequences in heterochromatin pose multiple challenges for the maintenance of genome stability. Cells have evolved sophisticated and highly controlled mechanisms to overcome these constraints. Here, we summarize recent findings on how the heterochromatic state influences DNA damage formation, signaling, and repair...
September 2018: Chromosoma
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