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https://www.readbyqxmd.com/read/28723680/meiotic-recombination-in-the-giraffe-g-reticulata
#1
Miluse Vozdova, Jan Fröhlich, Svatava Kubickova, Hana Sebestova, Jiri Rubes
Recently, the reticulated giraffe (G. reticulata) was identified as a distinct species, which emphasized the need for intensive research in this interesting animal. To shed light on the meiotic process as a source of biodiversity, we analysed the frequency and distribution of meiotic recombination in 2 reticulated giraffe males. We used immunofluorescence detection of synaptonemal complex protein (SYCP3), meiotic double strand breaks (DSB, marked as RAD51 foci) in leptonema, and crossovers (COs, as MLH1 foci) in pachynema...
July 20, 2017: Cytogenetic and Genome Research
https://www.readbyqxmd.com/read/28718829/aspirin-prevention-of-colorectal-cancer-focus-on-nf-%C3%AE%C2%BAb-signalling-and-the-nucleolus
#2
REVIEW
Jingyu Chen, Lesley A Stark
Overwhelming evidence indicates that aspirin and related non-steroidal anti-inflammatory drugs (NSAIDs) have anti-tumour activity and the potential to prevent cancer, particularly colorectal cancer. However, the mechanisms underlying this effect remain hypothetical. Dysregulation of the nuclear factor-kappaB (NF-κB) transcription factor is a common event in many cancer types which contributes to tumour initiation and progression by driving expression of pro-proliferative/anti-apoptotic genes. In this review, we will focus on the current knowledge regarding NSAID effects on the NF-κB signalling pathway in pre-cancerous and cancerous lesions, and the evidence that these effects contribute to the anti-tumour activity of the agents...
July 18, 2017: Biomedicines
https://www.readbyqxmd.com/read/28706212/epigenetics-of-the-preferential-silencing-of-brachypodium-stacei-originated-35s-rdna-loci-in-the-allotetraploid-grass-brachypodium-hybridum
#3
Natalia Borowska-Zuchowska, Robert Hasterok
Nucleolar dominance (ND), initially described as 'differential amphiplasty', is a phenomenon observed in some plant and animal allopolyploids and hybrids in which the selective suppression of the activity of 35S rRNA gene loci that have been inherited from one of the two or more ancestral genomes occurs. Although more than 80 years have passed since the discovery of ND, there is still a significant lack in our understanding of the mechanisms that determine this phenomenon. Here, we aimed to investigate the epigenetic status of 35S rRNA gene loci in the monocotyledonous Brachypodium hybridum, which is an allotetraploid that has resulted from a cross between B...
July 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28704696/the-function-of-dna-binding-protein-nucleophosmin-in-aav-replication
#4
Stifani Satkunanathan, Robin Thorpe, Yuan Zhao
Adeno-associated viruses (AAV) contain minimal viral proteins necessary for their replication. During virus assembly, AAV acquire, inherently and submissively, various cellular proteins. Our previous studies identified the association of AAV vectors with the DNA binding protein nucleophosmin (NPM1). Nucleophosmin has been reported to enhance AAV infection by mobilizing AAV capsids into and out of the nucleolus, indicating the importance of NPM1 in the AAV life cycle; however the role of NPM1 in AAV production remains unknown...
July 10, 2017: Virology
https://www.readbyqxmd.com/read/28692326/deletion-of-eif2%C3%AE-lysine-stretches-creates-a-dominant-negative-that-affects-the-translation-and-proliferation-in-human-cell-line-a-tool-for-arresting-the-cell-growth
#5
Gabrielle Dias Salton, Claudia Cilene Fernandes Correia Laurino, Nicolás Oliveira Mega, Andrés Delgado-Cañedo, Niclas Setterblad, Maryvonnick Carmagnat, Ricardo Machado Xavier, Elizabeth Cirne-Lima, Guido Lenz, João Antonio Pêgas Henriques, Jomar Pereira Laurino
BACKGROUND: Eukaryote initiation factor 2 subunit β (eIF2β) plays a crucial role in regulation protein synthesis, which mediates the interaction of eIF2 with mRNA. eIF2β contains evolutionarily conserved polylysine stretches in amino-terminal region and a zinc finger motif in the carboxy-terminus. METHODS: The gene eIF2β was cloned under tetracycline transcription control and the polylysine stretches were deleted by site-directed mutagenesis (eIF2βΔ3K). The plasmid was transfected into HEK 293 TetR cells...
July 10, 2017: Cancer Biology & Therapy
https://www.readbyqxmd.com/read/28685141/placeholder-factors-in-ribosome-biogenesis-please-pave-my-way
#6
REVIEW
Francisco J Espinar-Marchena, Reyes Babiano, Jesús Cruz
The synthesis of cytoplasmic eukaryotic ribosomes is an extraordinarily energy-demanding cellular activity that occurs progressively from the nucleolus to the cytoplasm. In the nucleolus, precursor rRNAs associate with a myriad of trans-acting factors and some ribosomal proteins to form pre-ribosomal particles. These factors include snoRNPs, nucleases, ATPases, GTPases, RNA helicases, and a vast list of proteins with no predicted enzymatic activity. Their coordinate activity orchestrates in a spatiotemporal manner the modification and processing of precursor rRNAs, the rearrangement reactions required for the formation of productive RNA folding intermediates, the ordered assembly of the ribosomal proteins, and the export of pre-ribosomal particles to the cytoplasm; thus, providing speed, directionality and accuracy to the overall process of formation of translation-competent ribosomes...
April 27, 2017: Microbial Cell
https://www.readbyqxmd.com/read/28671574/the-nucleolus-in-genome-maintenance-and-repair
#7
REVIEW
Maria Tsekrekou, Kalliopi Stratigi, Georgia Chatzinikolaou
The nucleolus is the subnuclear membrane-less organelle where rRNA is transcribed and processed and ribosomal assembly occurs. During the last 20 years, however, the nucleolus has emerged as a multifunctional organelle, regulating processes that go well beyond its traditional role. Moreover, the unique organization of rDNA in tandem arrays and its unusually high transcription rates make it prone to unscheduled DNA recombination events and frequent RNA:DNA hybrids leading to DNA double strand breaks (DSBs). If not properly repaired, rDNA damage may contribute to premature disease onset and aging...
July 1, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28657087/halides-tuning-the-subcellular-targeting-in-two-photon-emissive-complexes-via-different-uptake-mechanisms
#8
Xiaohe Tian, Yingzhong Zhu, Qiong Zhang, Ruilong Zhang, Jieying Wu, Yupeng Tian
We reported a simple and universal strategy by tuning halides (Cl, Br and I) in terpyridine-Zn(ii) complexes to achieve different subcellular organelle targeting (nucleolus, nucleus and intracellular membrane systems, respectively) via different cellular uptake mechanisms, resulting from halide triggering different polymorphs of these complexes.
June 28, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28656213/bmh-21-inhibits-viability-and-induces-apoptosis-by-p53-dependent-nucleolar-stress-responses-in-skov3-ovarian-cancer-cells
#9
Xinxu Fu, Lu Xu, Ling Qi, Hongyan Tian, Dan Yi, Yang Yu, Shibing Liu, Songyan Li, Ye Xu, Chunyan Wang
The nucleolus is a stress sensor associated with cell cycle progression and apoptosis. Studies have shown that nucleolar stress is positively correlated with apoptosis in breast, prostate and lung cancer cells. However, the role and function of nucleolar stress in ovarian cancer has not been reported. In this study, we found that the nucleolar stress inducer BMH-21 inhibited viability of SKOV3 ovarian cancer cells in a dose-dependent manner. Furthermore, BMH-21 induced the expression of nucleolar stress marker proteins (nucleolin, nucleophosmin and fibrillarin) and promoted the nuclear export of these proteins...
June 23, 2017: Oncology Reports
https://www.readbyqxmd.com/read/28654369/gymnotus-coatesi-gymnotiformes-a-case-of-colocation-of-multiple-sites-of-18s-rdna-with-telomeric-sequences
#10
Milla de Andrade Machado, Adauto Lima Cardoso, Susana Suely Rodrigues Milhomem-Paixão, Julio Cesar Pieczarka, Cleusa Yoshiko Nagamachi
Gymnotus coatesi is a small and rare species of banded knife fish that was originally described by LaMonte in 1935, found along the main stretch of the Amazon River. There is no described cytogenetic data on this species. We analyzed the karyotype of five specimens of G. coatesi collected from Cururutuia Stream in Bragança, Pará, Brazil. The obtained diploid number is 50 and the karyotypic formula is 24 m/sm +26 st/a. The constitutive heterochromatin is DAPI positive and distributed mainly in the centromeric and pericentromeric regions of the chromosomes...
June 27, 2017: Zebrafish
https://www.readbyqxmd.com/read/28654351/zz-z0-the-new-system-of-sex-chromosomes-in-eigenmannia-aff-trilineata-teleostei-gymnotiformes-sternopygidae-characterized-by-molecular-cytogenetics-and-dna-barcoding
#11
Cristian Araya-Jaime, Nadayca T Bonani Mateussi, Ricardo Utsunomia, Guilherme J Costa-Silva, Claudio Oliveira, Fausto Foresti
The cytogenetic characteristics of Eigenmannia aff. trilineata were analyzed by basic and molecular cytogenetics, applying fluorescent in situ hybridization, with 18S and 5S rDNA and U2 snRNA probes. The species revealed a kind of polymorphism associated to ZZ/Z0 type sex chromosomes, with 2n = 32 (8m+2sm+22a, NF = 42) in all males under analysis, whereas females evidenced 2n = 31 (8m+1sm+22a, NF = 40). C-banding showed constitutive heterochromatin restricted to the pericentromeric region of all chromosomes and single-nucleolus organized regions on pair 11...
June 27, 2017: Zebrafish
https://www.readbyqxmd.com/read/28652370/small-mitochondrial-arf-smarf-protein-corrects-p53-independent-developmental-defects-of-arf-tumor-suppressor-deficient-mice
#12
Jolieke G van Oosterwijk, Chunliang Li, Xue Yang, Joseph T Opferman, Charles J Sherr
The mouse p19(Arf) (human p14(ARF)) tumor suppressor protein, encoded in part from an alternative reading frame of the Ink4a (Cdkn2a) gene, inhibits the Mdm2 E3 ubiquitin ligase to activate p53. Arf is not expressed in most normal tissues of young mice but is induced by high thresholds of aberrant hyperproliferative signals, thereby activating p53 in incipient tumor cells that have experienced oncogene activation. The single Arf mRNA encodes two distinct polypeptides, including full-length p19(Arf) and N-terminally truncated and unstable p15(smArf) ("small mitochondrial Arf") initiated from an internal in-frame AUG codon specifying methionine-45...
July 11, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28640690/a-new-layer-of-rrna-regulation-by-small-interference-rnas-and-the-nuclear-rnai-pathway
#13
Xufei Zhou, Xiangyang Chen, Yun Wang, Xuezhu Feng, Shouhong Guang
Ribosome biogenesis drives cell growth and proliferation, but mechanisms that modulate this process remain poorly understood. For a long time, small ribosomal RNA sequences have been widely treated as non-specific degradation products and neglected as garbage sequences. Recently, we identified a new class of antisense ribosomal siRNAs (risiRNAs) that downregulate pre-rRNA through the nuclear RNAi pathway in C. elegans. risiRNAs exhibit sequence characteristics similar to 22G RNA while complement to 18S and 26S rRNA...
June 22, 2017: RNA Biology
https://www.readbyqxmd.com/read/28637749/cell-cycle-dependent-spatial-segregation-of-telomerase-from-sites-of-dna-damage
#14
Faissal Ouenzar, Maxime Lalonde, Hadrien Laprade, Geneviève Morin, Franck Gallardo, Samuel Tremblay-Belzile, Pascal Chartrand
Telomerase can generate a novel telomere at DNA double-strand breaks (DSBs), an event called de novo telomere addition. How this activity is suppressed remains unclear. Combining single-molecule imaging and deep sequencing, we show that the budding yeast telomerase RNA (TLC1 RNA) is spatially segregated to the nucleolus and excluded from sites of DNA repair in a cell cycle-dependent manner. Although TLC1 RNA accumulates in the nucleoplasm in G1/S, Pif1 activity promotes TLC1 RNA localization in the nucleolus in G2/M...
June 21, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28636660/cellular-sensitivity-to-uv-irradiation-is-mediated-by-rna-polymerase-i-transcription
#15
Robin Assfalg, Marius Costel Alupei, Maximilian Wagner, Sylvia Koch, Omar Garcia Gonzalez, Adrian Schelling, Karin Scharffetter-Kochanek, Sebastian Iben
The nucleolus has long been considered to be a pure ribosome factory. However, over the last two decades it became clear that the nucleolus is involved in numerous other functions besides ribosome biogenesis. Our experiments indicate that the activity of RNA polymerase I (Pol I) transcription monitors the integrity of the DNA and influences the response to nucleolar stress as well as the rate of survival. Cells with a repressed ribosomal DNA (rDNA) transcription activity showed an increased and prolonged p53 stabilisation after UVC-irradiation...
2017: PloS One
https://www.readbyqxmd.com/read/28634865/dynamics-of-tobacco-dna-topoisomerases-ii-in-cell-cycle-regulation-to-manage-topological-constrains-during-replication-transcription-and-mitotic-chromosome-condensation-and-segregation
#16
Badri Nath Singh, V Mohan Murali Achary, Varakumar Panditi, Sudhir K Sopory, Malireddy K Reddy
The topoisomerase II expression varies as a function of cell proliferation. Maximal topoisomerase II expression was tightly coupled to S phase and G2/M phase via both transcriptional and post-transcriptional regulation. Investigation in meiosis using pollen mother cells also revealed that it is not the major component of meiotic chromosomes, it seems to diffuse out once meiotic chromosomal condensation is completed. Synchronized tobacco BY-2 cell cultures were used to study the role of topoisomerase II in various stages of the cell cycle...
June 20, 2017: Plant Molecular Biology
https://www.readbyqxmd.com/read/28629776/unveiling-the-non-repair-face-of-the-base-excision-repair-pathway-in-rna-processing-a-missing-link-between-dna-repair-and-gene-expression
#17
REVIEW
Giulia Antoniali, Matilde Clarissa Malfatti, Gianluca Tell
The Base Excision Repair (BER) pathway, initially studied as a mere DNA repair pathway, has been later found to be implicated in the expression of cancer related genes in human. For several years, this intricate involvement in apparently different processes represented a mystery, which we now are starting to unveil. The BER handles simple alkylation and oxidative lesions arising from both endogenous and exogenous sources, including cancer therapy agents. Surprisingly, BER pathway involvement in transcriptional regulation, immunoglobulin variability and switch recombination, RNA metabolism and nucleolar function is astonishingly consolidating...
June 9, 2017: DNA Repair
https://www.readbyqxmd.com/read/28623274/reduction-in-chromosome-mobility-accompanies-nuclear-organization-during-early-embryogenesis-in-caenorhabditis-elegans
#18
Ritsuko Arai, Takeshi Sugawara, Yuko Sato, Yohei Minakuchi, Atsushi Toyoda, Kentaro Nabeshima, Hiroshi Kimura, Akatsuki Kimura
In differentiated cells, chromosomes are packed inside the cell nucleus in an organised fashion. In contrast, little is known about how chromosomes are packed in undifferentiated cells and how nuclear organization changes during development. To assess changes in nuclear organization during the earliest stages of development, we quantified the mobility of a pair of homologous chromosomal loci in the interphase nuclei of Caenorhabditis elegans embryos. The distribution of distances between homologous loci was consistent with a random distribution up to the 8-cell stage but not at later stages...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28622108/fluctuations-of-pol-i-and-fibrillarin-contents-of-the-nucleoli
#19
M Hornáček, L Kováčik, T Mazel, D Cmarko, E Bártová, I Raška, E Smirnov
Nucleoli are formed on the basis of ribosomal DNA (rDNA) clusters called Nucleolus Organizer Regions (NORs). Each NOR contains multiple genes coding for RNAs of the ribosomal particles. The prominent components of the nucleolar ultrastructure, fibrillar centers (FC) and dense fibrillar components (DFC), together compose FC/DFC units. These units are centers of rDNA transcription by RNA polymerase I (pol I), as well as the early processing events, in which an essential role belongs to fibrillarin. Each FC/DFC unit probably corresponds to a single transcriptionally active gene...
June 16, 2017: Nucleus
https://www.readbyqxmd.com/read/28611663/epigenetic-modifications-to-h3k9-in-renal-tubulointerstitial-cells-after-unilateral-ureteric-obstruction-and-tgf-%C3%AE-1-stimulation
#20
Timothy D Hewitson, Stephen G Holt, Sven-Jean Tan, Belinda Wigg, Chrishan S Samuel, Edward R Smith
Introduction: Epigenetic regulation of fibrogenesis through post-translational histone modifications (marks) may be a key determinant of progression in renal disease. In this study, we examined the distribution and acquisition of histone 3 Lysine 9 (H3K9) marks after injury and stimulation with the pro-fibrotic cytokine TGF-β1. Our focus was on their presence in activated fibroblasts (myofibroblasts) and epithelial cells (epithelial-mesenchymal transition). Methods and Results: Immunofluorescent microscopy was used to examine global H3K9 acetylation (H3K9Ac) and tri-methylation (H3K9Me3) after unilateral ureteric obstruction (UUO) in mice...
2017: Frontiers in Pharmacology
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