Search results for "Duplication"
showing 10 items of 216 documents
Eight million years of maintained heterozygosity in chromosome homologs of cercopithecine monkeys
2020
In the Cercopithecini ancestor two chromosomes, homologous to human chromosomes 20 and 21, fused to form the Cercopithecini specific 20/21 association. In some individuals from the genus Cercopithecus, this association was shown to be polymorphic for the position of the centromere, suggesting centromere repositioning events. We set out to test this hypothesis by defining the evolutionary history of the 20/21 association in four Cercopithecini species from three different genera. The marker order of the various 20/21 associations was established using molecular cytogenetic techniques, including an array of more than 100 BACs. We discovered that five different forms of the 20/21 association w…
Tumor cells can escape DNA-damaging cisplatin through DNA endoreduplication and reversible polyploidy
2008
Cancer chemotherapy can induce tumor regression followed, in many cases, by relapse in the long-term. Thus this study was performed to assess the determinants of such phenomenon using an in vivo cancer model and in vitro approaches. When animals bearing an established tumor are treated by cisplatin, the tumor initially undergoes a dramatic shrinkage and is characterized by giant tumor cells that do not proliferate but maintain DNA synthesis. After several weeks of latency, the tumor resumes its progression and consists of small proliferating cells. Similarly, when tumor cells are exposed in vitro to pharmacological concentrations of cisplatin, mitotic activity stops initially but cells main…
The ideal duplication
2021
AbstractIn this paper we present and study the ideal duplication, a new construction within the class of the relative ideals of a numerical semigroup S, that, under specific assumptions, produces a relative ideal of the numerical duplication $$S\bowtie ^b E$$ S ⋈ b E . We prove that every relative ideal of the numerical duplication can be uniquely written as the ideal duplication of two relative ideals of S; this allows us to better understand how the basic operations of the class of the relative ideals of $$S\bowtie ^b E$$ S ⋈ b E work. In particular, we characterize the ideals E such that $$S\bowtie ^b E$$ S ⋈ b E is nearly Gorenstein.
Missing values in deduplication of electronic patient data
2011
Data deduplication refers to the process in which records referring to the same real-world entities are detected in datasets such that duplicated records can be eliminated. The denotation ‘record linkage’ is used here for the same problem.1 A typical application is the deduplication of medical registry data.2 3 Medical registries are institutions that collect medical and personal data in a standardized and comprehensive way. The primary aims are the creation of a pool of patients eligible for clinical or epidemiological studies and the computation of certain indices such as the incidence in order to oversee the development of diseases. The latter task in particular requires a database in wh…
The DNA-binding subunit p140 of replication factor C is upregulated in cycling cells and associates with G 1 phase cell cycle regulatory proteins
1999
The DNA-binding subunit of replication factor C (RFCp140) plays an important role in both DNA replication and DNA repair. The mechanisms regulating activation of RFCp140 thereby controlling replication and cellular proliferation are largely unknown. We analyzed protein expression of RFCp140 during cell cycle progression and investigated the association of RFCp140 with cell cycle regulatory proteins in cell lines of various tissue origin and in primary hematopoietic cells. Western and Northern blot analyses of RFCp140 from synchronized cells showed downregulation of RFCp140 when cells enter a G0-like quiescent state and upregulation of RFCp140 in cycling cells. Translocation from the cytopla…
Preservation of genetic and regulatory robustness in ancient gene duplicates of Saccharomyces cerevisiae
2014
[EN] Biological systems remain robust against certain genetic and environmental challenges. Robustness allows the exploration of ecological adaptations. It is unclear what factors contribute to increasing robustness. Gene duplication has been considered to increase genetic robustness through functional redundancy, accelerating the evolution of novel functions. However, recent findings have questioned the link between duplication and robustness. In particular, it remains elusive whether ancient duplicates still bear potential for innovation through preserved redundancy and robustness. Here we have investigated this question by evolving the yeast Saccharomyces cerevisiae for 2200 generations …
The Physcomitrella genome reveals evolutionary insights into the conquest of land by plants
2008
We report the draft genome sequence of the model moss Physcomitrella patens and compare its features with those of flowering plants, from which it is separated by more than 400 million years, and unicellular aquatic algae. This comparison reveals genomic changes concomitant with the evolutionary movement to land, including a general increase in gene family complexity; loss of genes associated with aquatic environments (e.g., flagellar arms); acquisition of genes for tolerating terrestrial stresses (e.g., variation in temperature and water availability); and the development of the auxin and abscisic acid signaling pathways for coordinating multicellular growth and dehydration response. The …
The high rate of endoreduplication in the repair deficient CHO mutant EM9 parallels a reduced level of methylated deoxycytidine in DNA
2008
It has been recently proposed that hypomethylation of DNA induced by 5-azacytidine (5-azaC) leads to reduced chromatid decatenation that ends up in endoreduplication, most likely due to a failure in topo II function [S. Mateos, I. Domínguez, N. Pastor, G. Cantero, F. Cortés, The DNA demethylating 5-azaC induces endoreduplication in cultured Chinese hamster cells, Mutat. Res. 578 (2005) 33-42]. The Chinese hamster mutant cell line EM9 has a high spontaneous frequency of endoreduplication as compared to its parental line AA8. In order to see if this is related to the degree of DNA methylation, we have investigated the basal levels of both endpoints in AA8 and EM9, as well as the effect of ext…
Replication origins and pause sites in sea urchin mitochondrial DNA
1992
We have used a combination of one- and two-dimensional agarose gel electrophoresis, and solution hybridization to strand-specific probes, to map the replication origin of sea urchin mitochondrial DNA and to investigate the structure of replication intermediates. These assays are consistent with replication initiating unidirectionally from the D-loop region by D-loop expansion, as in vertebrates. A prominent site of initiation of lagging-strand synthesis lies at, or near to, the boundary between the genes for ATPase 6 and COIII, which is also close to a pause site for leading-strand synthesis. These findings suggest a role for pause sites in the regulation of mitochondrial transcription and …
Multiple roles for ISWI in transcription, chromosome organization and DNA replication.
2003
ISWI functions as the ATPase subunit of multiple chromatin-remodeling complexes. These complexes use the energy of ATP hydrolysis to slide nucleosomes and increase chromatin fluidity, thereby modulating the access of transcription factors and other regulatory proteins to DNA. Here we discuss recent progress toward understanding the biological functions of ISWI, with an emphasis on its roles in transcription, chromosome organization and DNA replication.