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https://www.readbyqxmd.com/read/28108587/meiotic-crossing-over-in-maize-knob-heterochromatin
#1
Stephen M Stack, Lindsay A Shearer, Leslie Lohmiller, Lorinda K Anderson
There is ample evidence that crossing over is suppressed in heterochromatin associated with centromeres and nucleolus organizers (NORs). This characteristic has been attributed to all heterochromatin, but the generalization may not be justified. To investigate the relation of crossing over to heterochromatin that is not associated with centromeres or NORs, we used a combination of fluorescence in situ hybridization of the maize 180 bp knob repeat to show the locations of knob heterochromatin and fluorescent immunolocalization of MLH1 protein and AFD1 protein to show the locations of MLH1 foci on maize synaptonemal complexes (SCs ~ pachytene chromosomes)...
January 20, 2017: Genetics
https://www.readbyqxmd.com/read/28106789/centromere-stability-the-replication-connection
#2
REVIEW
Susan L Forsburg, Kuo-Fang Shen
The fission yeast centromere, which is similar to metazoan centromeres, contains highly repetitive pericentromere sequences that are assembled into heterochromatin. This is required for the recruitment of cohesin and proper chromosome segregation. Surprisingly, the pericentromere replicates early in the S phase. Loss of heterochromatin causes this domain to become very sensitive to replication fork defects, leading to gross chromosome rearrangements. This review examines the interplay between components of DNA replication, heterochromatin assembly, and cohesin dynamics that ensures maintenance of genome stability and proper chromosome segregation...
January 18, 2017: Genes
https://www.readbyqxmd.com/read/28101375/aurora-a-promotes-the-establishment-of-spindle-assembly-checkpoint-by-priming-the-haspin-aurora-b-feedback-loop-in-late-g2-phase
#3
Fazhi Yu, Ya Jiang, Lucy Lu, Mimi Cao, Yulong Qiao, Xing Liu, Dan Liu, Terry Van Dyke, Fangwei Wang, Xuebiao Yao, Jing Guo, Zhenye Yang
Aurora-A kinase functions mainly in centrosome maturation, separation and spindle formation. It has also been found to be amplified or overexpressed in a range of solid tumors, which is linked with tumor progression and poor prognosis. Importantly, Aurora-A inhibitors are being studied in a number of ongoing clinical trials. However, whether and how Aurora-A has a role in the regulation of the mitotic checkpoint is controversial. Additionally, the function of nuclear-accumulated Aurora-A in late G2 phase is not clear...
2017: Cell Discovery
https://www.readbyqxmd.com/read/28094382/the-supercoiling-state-of-dna-determines-the-handedness-of-both-h3-and-cenp-a-nucleosomes
#4
R Vlijm, S H Kim, P L De Zwart, Y Dalal, C Dekker
Nucleosomes form the unit structure of the genome in eukaryotes, thereby constituting a fundamental tenet of chromatin biology. In canonical nucleosomes, DNA wraps around the histone octamer in a left-handed toroidal ramp. Here, in single-molecule magnetic tweezers studies of chaperone-assisted nucleosome assembly, we show that the handedness of the DNA wrapping around the nucleosome core is intrinsically ambidextrous, and depends on the pre-assembly supercoiling state of the DNA, i.e., it is not uniquely determined by the octameric histone core...
January 17, 2017: Nanoscale
https://www.readbyqxmd.com/read/28088192/nucleotide-diversity-inflation-as-a-genome-wide-response-to-experimental-lifespan-extension-in-drosophila-melanogaster
#5
Pawel Michalak, Lin Kang, Pernille M Sarup, Mads F Schou, Volker Loeschcke
BACKGROUND: Evolutionary theory predicts that antagonistically selected alleles, such as those with divergent pleiotropic effects in early and late life, may often reach intermediate population frequencies due to balancing selection, an elusive process when sought out empirically. Alternatively, genetic diversity may increase as a result of positive frequency-dependent selection and genetic purging in bottlenecked populations. RESULTS: While experimental evolution systems with directional phenotypic selection typically result in at least local heterozygosity loss, we report that selection for increased lifespan in Drosophila melanogaster leads to an extensive genome-wide increase of nucleotide diversity in the selected lines compared to replicate control lines, pronounced in regions with no or low recombination, such as chromosome 4 and centromere neighborhoods...
January 14, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28087838/does-the-assessment-of-non-disjunction-provide-a-more-sensitive-assay-for-detection-of-aneugens
#6
Joanne M Elloway, Alexandra K Davies, Julie Hayes, Ann T Doherty
The detection of aneugenic chemicals is important due to the implications of aneuploidy for human health. Aneuploidy can result from chromosome loss or non-disjunction due to chromosome mis-segregation at anaphase. Frequently, aneugens are detected using the in vitro micronucleus assay (IVM), with either centromere or kinetochore labelling. However, this method does not consider non-disjunction, the suggested predominant mechanism of spindle poison induced aneugenicity in primary human lymphocytes. Therefore, the IVM may be relatively insensitive in detecting aneuploidy...
January 13, 2017: Toxicological Sciences: An Official Journal of the Society of Toxicology
https://www.readbyqxmd.com/read/28087831/a-tale-of-two-cenpcs-centromere-localization-of-kinetochore-null-2-and-cenp-c
#7
Jennifer Mach
No abstract text is available yet for this article.
January 13, 2017: Plant Cell
https://www.readbyqxmd.com/read/28081279/karyotype-analysis-and-ribosomal-gene-localization-of-spotted-knifejaw-oplegnathus-punctatus
#8
P Z Li, D D Cao, X B Liu, Y J Wang, H Y Yu, X J Li, Q Q Zhang, X B Wang
The spotted knifejaw, Oplegnathus punctatus, is an important aquaculture fish species in China. To better understand the chromosomal microstructure and the karyotypic origin of this species, cytogenetic analysis was performed using Giemsa staining to identify metaphase chromosomes, C-banding to detect C-positive heterochromatin, silver staining to identify the nucleolus organizer regions (Ag-NORs), and fluorescence in situ hybridization (FISH) for physical mapping of the major (18S rDNA) and minor (5S rDNA) ribosomal genes...
December 23, 2016: Genetics and Molecular Research: GMR
https://www.readbyqxmd.com/read/28081238/genomic-organization-of-repetitive-dna-in-woodpeckers-aves-piciformes-implications-for-karyotype-and-zw-sex-chromosome-differentiation
#9
Thays Duarte de Oliveira, Rafael Kretschmer, Natasha Avila Bertocchi, Tiago Marafiga Degrandi, Edivaldo Herculano Corrêa de Oliveira, Marcelo de Bello Cioffi, Analía Del Valle Garnero, Ricardo José Gunski
Birds are characterized by a low proportion of repetitive DNA in their genome when compared to other vertebrates. Among birds, species belonging to Piciformes order, such as woodpeckers, show a relatively higher amount of these sequences. The aim of this study was to analyze the distribution of different classes of repetitive DNA-including microsatellites, telomere sequences and 18S rDNA-in the karyotype of three Picidae species (Aves, Piciformes)-Colaptes melanochloros (2n = 84), Colaptes campestris (2n = 84) and Melanerpes candidus (2n = 64)-by means of fluorescence in situ hybridization...
2017: PloS One
https://www.readbyqxmd.com/read/28079247/dynamic-location-changes-of-bub1-phosphorylated-h2athr133-with-cenh3-nucleosome-in-maize-centromeric-regions
#10
Handong Su, Yalin Liu, Qianhua Dong, Chao Feng, Jing Zhang, Yang Liu, James A Birchler, Fangpu Han
The genomic stability of all organisms requires precise cell division with proper chromosome orientation. The Bub1-H2Aph-Sgo1 pathway and spindle assembly checkpoint (SAC) components have been identified in yeast and mammals that are important for sister centromere orientation and chromosome segregation. However, their roles in plants are not clear. Maize meiotic mutants and minichromosomes were used to study the role of H2AThr133 phosphorylation and SAC components in sister centromere orientation and chromosome segregation...
January 12, 2017: New Phytologist
https://www.readbyqxmd.com/read/28074901/live-visualization-of-genomic-loci-with-bifc-tale
#11
Huan Hu, Hongmin Zhang, Sheng Wang, Miao Ding, Hui An, Yingping Hou, Xiaojing Yang, Wensheng Wei, Yujie Sun, Chao Tang
Tracking the dynamics of genomic loci is important for understanding the mechanisms of fundamental intracellular processes. However, fluorescent labeling and imaging of such loci in live cells have been challenging. One of the major reasons is the low signal-to-background ratio (SBR) of images mainly caused by the background fluorescence from diffuse full-length fluorescent proteins (FPs) in the living nucleus, hampering the application of live cell genomic labeling methods. Here, combining bimolecular fluorescence complementation (BiFC) and transcription activator-like effector (TALE) technologies, we developed a novel method for labeling genomic loci (BiFC-TALE), which largely reduces the background fluorescence level...
January 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28073008/cenp-a-modifications-on-ser68-and-lys124-are-dispensable-for-establishment-maintenance-and-long-term-function-of-human-centromeres
#12
Daniele Fachinetti, Glennis A Logsdon, Amira Abdullah, Evan B Selzer, Don W Cleveland, Ben E Black
CENP-A is a histone H3 variant key to epigenetic specification of mammalian centromeres. Using transient overexpression of CENP-A mutants, two recent reports in Developmental Cell proposed essential centromere functions for post-translational modifications of human CENP-A. Phosphorylation at Ser68 was proposed to have an essential role in CENP-A deposition at centromeres. Blockage of ubiquitination at Lys124 was proposed to abrogate localization of CENP-A to the centromere. Following gene inactivation and replacement in human cells, we demonstrate that CENP-A mutants that cannot be phosphorylated at Ser68 or ubiquitinated at Lys124 assemble efficiently at centromeres during G1, mediate early events in centromere establishment at an ectopic chromosomal locus, and maintain centromere function indefinitely...
January 9, 2017: Developmental Cell
https://www.readbyqxmd.com/read/28072975/-molecular-features-of-metanephric-adenoma-and-their-values-in-differential-diagnosis
#13
X Wang, S S Shi, W R Yang, S B Ye, R Li, H H Ma, R S Zhang, Z F Lu, X J Zhou, Q Rao
Objective: To study the molecular features of metanephric adenoma (MA) and discuss their values in differential diagnosis. Methods: BRAF V600E immunohistochemistry (IHC) using the mutation-specific VE1 monoclonal antibody and Sanger sequencing of BRAF mutations were performed on 21 MAs, 16 epithelial-predominant Wilms tumors (e-WT) and 20 the solid variant of papillary renal cell carcinomas (s-PRCC) respectively. p16 protein was detected by IHC also. Fluorescence in situ hybridization (FISH) analyses using centromeric probes for chromosome 7 and 17 were performed on the three renal tumors in parallel...
January 8, 2017: Zhonghua Bing Li Xue za Zhi Chinese Journal of Pathology
https://www.readbyqxmd.com/read/28072905/saccharomyces-cerevisiae-shuttle-vectors
#14
REVIEW
Robert Gnügge, Fabian Rudolf
Yeast shuttle vectors are indispensable tools in yeast research. They enable cloning of defined DNA sequences in Escherichia coli and their direct transfer into Saccharomyces cerevisiae cells. There are three types of commonly used yeast shuttle vectors: centromeric plasmids, episomal plasmids and integrating plasmids. In this review, we discuss the different plasmid systems and their characteristic features. We focus on their segregational stability and copy number and indicate how to modify these properties...
January 10, 2017: Yeast
https://www.readbyqxmd.com/read/28069312/centromeres-drive-a-hard-bargain
#15
REVIEW
Leah F Rosin, Barbara G Mellone
Centromeres are essential chromosomal structures that mediate the accurate distribution of genetic material during meiotic and mitotic cell divisions. In most organisms, centromeres are epigenetically specified and propagated by nucleosomes containing the centromere-specific H3 variant, centromere protein A (CENP-A). Although centromeres perform a critical and conserved function, CENP-A and the underlying centromeric DNA are rapidly evolving. This paradox has been explained by the centromere drive hypothesis, which proposes that CENP-A is undergoing an evolutionary tug-of-war with selfish centromeric DNA...
January 6, 2017: Trends in Genetics: TIG
https://www.readbyqxmd.com/read/28067606/chromosomal-mapping-of-repetitive-sequences-rex3-rex6-and-rdna-genes-in-hybrids-between-colossoma-macropomum-cuvier-1818-and-piaractus-mesopotamicus-holmberg-1887
#16
Leila Braga Ribeiro, Americo Moraes Neto, Roberto Ferreira Artoni, Daniele Aparecida Matoso, Eliana Feldberg
Some species of Characiformes are known for their high economic value, such as Colossoma macropomum and Piaractus mesopotamicus, and are used in aquaculture programs to generate hybrid tambacu (interbreeding of C. macropomum females and P. mesopotamicus males). The present work aimed to investigate the location of the Rex3 and Rex6 transposable elements in the hybrid and in the species, in addition to checking the genomic organization of the 18S and 5S rDNA in tambacu. The diploid number found for the hybrid was equal to 54 chromosomes, with heterochromatic blocks distributed mainly in the centromeric portions...
January 9, 2017: Zebrafish
https://www.readbyqxmd.com/read/28062749/targeting-of-a-thaliana-knl2-to-centromeres-depends-on-the-conserved-cenpc-k-motif-in-its-c-terminus
#17
Michael Sandmann, Paul Talbert, Dmitri Demidov, Markus Kuhlmann, Twan Rutten, Udo Conrad, Inna Lermontova
KNL2 (KINETOCHORE NULL 2) is involved in recognition of centromeres and in centromeric localization of the centromere-specific histone cenH3. Our study revealed a cenH3 nucleosome-binding CENPC-k motif at the C-terminus of Arabidopsis thaliana KNL2, which is conserved among a wide spectrum of eukaryotes. Centromeric localization of KNL2 is abolished by deletion of the CENPC-k motif and by mutating single conserved amino acids, but can be restored by insertion of the corresponding motif of A. thaliana CENP-C...
January 6, 2017: Plant Cell
https://www.readbyqxmd.com/read/28061478/mitotic-control-of-human-papillomavirus-genome-containing-cells-is-regulated-by-the-function-of-the-pdz-binding-motif-of-the-e6-oncoprotein
#18
Elizabeth K Marsh, Craig P Delury, Nicholas J Davies, Christopher J Weston, Mohammed A L Miah, Lawrence Banks, Joanna L Parish, Martin R Higgs, Sally Roberts
The function of a conserved PDS95/DLG1/ZO1 (PDZ) binding motif (E6 PBM) at the C-termini of E6 oncoproteins of high-risk human papillomavirus (HPV) types contributes to the development of HPV-associated malignancies. Here, using a primary human keratinocyte-based model of the high-risk HPV18 life cycle, we identify a novel link between the E6 PBM and mitotic stability. In cultures containing a mutant genome in which the E6 PBM was deleted there was an increase in the frequency of abnormal mitoses, including multinucleation, compared to cells harboring the wild type HPV18 genome...
January 3, 2017: Oncotarget
https://www.readbyqxmd.com/read/28059702/cdk-regulated-dimerization-of-m18bp1-on-a-mis18-hexamer-is-necessary-for-cenp-a-loading
#19
Dongqing Pan, Kerstin Klare, Arsen Petrovic, Annika Take, Kai Walstein, Priyanka Singh, Arnaud Rondelet, Alexander W Bird, Andrea Musacchio
Centromeres are unique chromosomal loci that promote the assembly of kinetochores, macromolecular complexes that bind spindle microtubules during mitosis. In most organisms, centromeres lack defined genetic features. Rather, they are specified epigenetically by a centromere-specific histone H3 variant, CENP-A. The Mis18 complex, comprising the Mis18α:Mis18β subcomplex and M18BP1, is crucial for CENP-A homeostasis. It recruits the CENP-A-specific chaperone HJURP to centromeres and primes it for CENP-A loading...
January 6, 2017: ELife
https://www.readbyqxmd.com/read/28058701/correlation-between-chromosome-9p21-locus-deletion-and-prognosis-in-clinically-localized-prostate-cancer
#20
Érika Aparecida Felix de Barros, José Pontes-Junior, Sabrina Thalita Reis, Amanda Eunice Ramos Lima, Isida C Souza, Jose Lucas Salgueiro, Douglas Fontes, Humberto Dellê, Rafael Ferreira Coelho, Nayara Izabel Viana, Kátia Ramos Moreira Leite, William C Nahas, Miguel Srougi
BACKGROUND: Some studies have reported that deletions at chromosome arm 9p occur frequently and represent a critical step in carcinogenesis of some neoplasms. Our aim was to evaluate the deletion of locus 9p21 and chromosomes 3, 7 and 17 in localized prostate cancer (PC) and correlate these alterations with prognostic factors and biochemical recurrence after surgery. METHODS: We retrospectively evaluated surgical specimens from 111 patients with localized PC who underwent radical prostatectomy...
January 5, 2017: International Journal of Biological Markers
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