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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
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
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
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
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
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
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
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
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
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
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
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
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
Andrea Enguita-Marruedo, Wiggert A Van Cappellen, Jos W Hoogerbrugge, Fabrizia Carofiglio, Evelyne Wassenaar, Johan A Slotman, Adriaan Houtsmuller, Willy M Baarends
During mammalian meiotic prophase, homologous chromosomes connect through the formation of the synaptonemal complex (SC). SYCP3 is a component of the lateral elements of the SC. We have generated transgenic mice expressing N- or C-terminal fluorescent-tagged SYCP3 (mCherry-SYCP3 (CSYCP) and SYCP3-mCherry (SYCPC)) to study SC dynamics and chromosome movements in vivo. Neither transgene rescued meiotic aberrations in Sycp3 knockouts, but CSYCP could form short axial element-like structures in the absence of endogenous SYCP3...
September 2018: Chromosoma
Shashank Srivastava, Daniel R Foltz
Centromeres are specialized chromosome domain that serve as the site for kinetochore assembly and microtubule attachment during cell division, to ensure proper segregation of chromosomes. In higher eukaryotes, the identity of active centromeres is marked by the presence of CENP-A (centromeric protein-A), a histone H3 variant. CENP-A forms a centromere-specific nucleosome that acts as a foundation for centromere assembly and function. The posttranslational modification (PTM) of histone proteins is a major mechanism regulating the function of chromatin...
September 2018: Chromosoma
Francisco J Ruiz-Ruano, Jesús Castillo-Martínez, Josefa Cabrero, Ricardo Gómez, Juan Pedro M Camacho, María Dolores López-León
Satellite DNA (satDNA) constitutes an important fraction of repetitive DNA in eukaryotic genomes, but it is barely known in most species. The high-throughput analysis of satDNA in the grasshopper Pyrgomorpha conica revealed 87 satDNA variants grouped into 76 different families, representing 9.4% of the genome. Fluorescent in situ hybridization (FISH) analysis of the 38 most abundant satDNA families revealed four different patterns of chromosome distribution. Homology search between the 76 satDNA families showed the existence of 15 superfamilies, each including two or more families, with the most abundant superfamily representing more than 80% of all satDNA found in this species...
September 2018: Chromosoma
Haoyang Xin, Tao Zhang, Yonghua Han, Yufeng Wu, Jisen Shi, Mengli Xi, Jiming Jiang
Dioecious species accounted for 6% of all plant species, including a number of crops and economically important species, such as poplar. However, sex determination and sex chromosome evolution have been studied only in few dioecious species. In poplar, the sex-determining locus was mapped to chromosome 19. Interestingly, this locus was mapped to either a peritelomeric or a centromeric region among different poplar species. We developed an oligonucleotide (oligo)-based chromosome painting probe based on the sequence of chromosome 19 from Populus trichocarpa...
September 2018: Chromosoma
Alexey I Makunin, Marija Rajičić, Tatyana V Karamysheva, Svetlana A Romanenko, Anna S Druzhkova, Jelena Blagojević, Mladen Vujošević, Nikolay B Rubtsov, Alexander S Graphodatsky, Vladimir A Trifonov
Supernumerary chromosomes sporadically arise in many eukaryotic species as a result of genomic rearrangements. If present in a substantial part of species population, those are called B chromosomes, or Bs. This is the case for 70 mammalian species, most of which are rodents. In humans, the most common types of extra chromosomes, sSMCs (small supernumerary marker chromosomes), are diagnosed in approximately 1 of 2000 postnatal cases. Due to low frequency in population, human sSMCs are not considered B chromosomes...
September 2018: Chromosoma
Franck Pellestor, Vincent Gatinois
The recent discovery of a new class of massive chromosomal rearrangements, occurring during one unique cellular event and baptized "chromothripsis," deeply modifies our perception on the genesis of complex genomic rearrangements, but also, it raises the question of the potential driving role of chromothripsis in species evolution. Analyses of the etiology of chromothripsis have led to the identification of various cellular processes capable of generating chromothripsis, such as premature chromosome condensation, telomere dysfunction, abortive apoptosis, and micronucleus formation...
August 7, 2018: Chromosoma
Yutaka Yamamoto, Susan A Gerbi
Targeted insertion of large pieces of DNA is an important goal of genetic engineering. However, this goal has been elusive since classical methods for homology-directed repair are inefficient and often not feasible in many systems. Recent advances are described here that enable site-specific genomic insertion of relatively large DNA with much improved efficiency. Using the preferred repair pathway in the cell of nonhomologous end-joining, DNA of up to several kb could be introduced with remarkably good precision by the methods of HITI and ObLiGaRe with an efficiency up to 30-40%...
July 12, 2018: Chromosoma
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