Search results for "nuclear DNA"
showing 10 items of 27 documents
Base composition of DNA from glomalean fungi: high amounts of methylated cytosine.
1997
Glomales (Zygomycetes) are obligate fungal symbionts of roots of land plants and form arbuscular mycorrhiza. Sporal DNA of 10 isolates belonging to nine species was purified and the base composition was determined by RP-HPLC. Base composition fell in a narrow range between 30 and 35% G + C. A high amount of methylated cytosine (mC) accounting for 2-4% of the total nucleotides was found in all taxa. The DNA melting profile was defined for Scutellospora castanea. It corresponded to 32% G + C, and the shape of the denaturation curve suggested a heterogeneity in the GC content within the fungal genome. Knowledge of GC contents and variations between taxa are essential for evaluating nuclear DNA…
The basal levels of 8-oxoG and other oxidative modifications in intact mitochondrial DNA are low even in repair-deficient (Ogg1(-/-)/Csb(-/-)) mice.
2007
Abstract Mitochondrial DNA (mtDNA) is assumed to be highly prone to damage by reactive oxygen species (ROS) because of its location in close proximity to the mitochondrial electron transport chain. Accordingly, mitochondrial oxidative DNA damage has been hypothesized to be responsible for various neurological diseases, ageing and cancer. Since 7,8-dihydro-8-oxoguanine (8-oxoG), one of the most frequent oxidative base modifications, is removed from the mitochondrial genome by the glycosylase OGG1, the basal levels of this lesion are expected to be highly elevated in Ogg1−/− mice. To investigate this hypothesis, we have used a mtDNA relaxation assay in combination with various repair enzymes …
Mitochondrial DNA effects on fitness in Drosophila subobscura
2011
We tested different fitness components on a series of conspecific mtDNA haplotypes, detected by RFLPs in Drosophila subobscura. Additionally, haplotype VIII, endemic to the Canary Islands, was tested upon its own native nuclear DNA background and upon that of the rest of mtDNAs tested herein. We found that both nuclear and mitochondrial DNA can have a significant effect upon their hosts' fitness, and that negative selection is one of the mechanisms that can intervene in this species' mtDNA haplotype pattern. We discuss the importance of this mechanism in relation to genetic drift, in the form of periodic population bottlenecks, and how the latter can enhance the former. We also detected a s…
Mitochondrial DNA sequences are present inside nuclear DNA in rat tissues and increase with age
2009
Abstract Mitochondrial DNA (mtDNA) mutations increase with age. However, the number of cells with predominantly mutated mtDNA is small in old animals. Here a new hypothesis is proposed: mtDNA fragments may insert into nuclear DNA contributing to aging and related diseases by alterations in the nucleus. Real-time PCR quantification shows that sequences of cytochrome oxidase III and 16S rRNA from mtDNA are present in highly purified nuclei from liver and brain in young and old rats. The sequences of these insertions revealed that they contain single nucleotide polymorphisms identical to those present in mtDNA of the same animal. Interestingly, the amount of mitochondrial sequences in nuclear …
Identification and potential origin of invasive clawed frogsXenopus(Anura: Pipidae) in Sicily based on mitochondrial and nuclear DNA
2013
African clawed frogs of the widespread polytypic species Xenopus laevis Daudin, 1802 (ranging large parts of sub-Saharan Africa) have been spreading since the 1940s, and have established reproductive populations in Europe, Asia and the Americas, where they can have negative impact as competitors of native amphibians and as disease vectors for chytridomycosis or ranaviruses. Here we use two mitochondrial (cytochrome b, 16S rDNA) and one nuclear (RAG 1: Recombination Associated Gene 1) DNA markers to infer the potential origin of invasive clawed frogs from Sicily that represent the largest invasive population in Europe. Identical mtDNA haplotypes match with those of Xenopus laevis, and Sicili…
Reactive oxygen species derived from the mitochondrial respiratory chain are not responsible for the basal levels of oxidative base modifications obs…
2004
The mitochondrial electron transport chain (ETC) is the most important source of reactive oxygen species (ROS) in mammalian cells. To assess its relevance to the endogenous generation of oxidative DNA damage in the nucleus, we have compared the background (steady-state) levels of oxidative DNA base modifications sensitive to the repair glycosylase Fpg (mostly 7,8-dihydro-8-oxoguanine) in wild-type HeLa cells and HeLa rho0 cells. The latter are depleted of mitochondrial DNA and therefore are unable to produce ROS in the ETC. Although the levels of ROS measured by flow cytometry and redox-sensitive probes in rho0 cells were only 10-15% those of wild-type cells, steady-state levels of oxidativ…
Nuclear DNA content variation inHalimiumandXolantha(Cistaceae)
2008
Abstract Chromosome numbers and nuclear DNA contents were determined in several taxa of two genera of Cistaceae, Halimium and Xolantha. The diploid chromosome number 2n = 18 is stable within the genus Halimium. In Xolantha, the diploid chromosome number 2n = 14 was confirmed in X. tuberaria, and hexaploid (2n = 36) and octoploid (2n = 48) cytotypes were found in X. guttata. DNA amounts, first reported here for these genera, were determined by flow cytometry of propidium iodide-stained nuclei. Within Halimium there is a more than twofold difference in genome size between H. calycinum (7.61 pg DNA) and H. atriplicifolium (3.66 pg DNA). Within the genus Xolantha, absolute genome sizes of 7.3 a…
“Mitotic Slippage” and Extranuclear DNA in Cancer Chemoresistance: A Focus on Telomeres
2020
Mitotic slippage (MS), the incomplete mitosis that results in a doubled genome in interphase, is a typical response of TP53-mutant tumors resistant to genotoxic therapy. These polyploidized cells display premature senescence and sort the damaged DNA into the cytoplasm. In this study, we explored MS in the MDA-MB-231 cell line treated with doxorubicin (DOX). We found selective release into the cytoplasm of telomere fragments enriched in telomerase reverse transcriptase (hTERT), telomere capping protein TRF2, and DNA double-strand breaks marked by γH2AX, in association with ubiquitin-binding protein SQSTM1/p62. This occurs along with the alternative lengthening of telomeres (ALT) and DNA repa…
Hybridization within the Rana ridibunda Complex of North Africa
1980
Abstract Cellogel electrophoretic study of the plasma protein pattern, especially the albumin fractions, and microdensitometric determination of erythrocyte nuclear DNA amount in 25 frogs of the Rana ridibunda complex from different localities in Morocco and Algeria allows the conclusion that two different forms of this complex are hybridizing in North Africa, as it is found in the Rana esculenta complex in Europe or in the East Asian green frogs. These forms can be identified by their albumin alleles, but not yet by their morphology. They produce mainly triploid hybrids.
p27Kip1participates in the regulation of endoreplication in differentiating chick retinal ganglion cells
2015
Nuclear DNA duplication in the absence of cell division (i.e. endoreplication) leads to somatic polyploidy in eukaryotic cells. In contrast to some invertebrate neurons, whose nuclei may contain up to 200,000-fold the normal haploid DNA amount (C), polyploid neurons in higher vertebrates show only 4C DNA content. To explore the mechanism that prevents extra rounds of DNA synthesis in these latter cells we focused on the chick retina, where a population of tetraploid retinal ganglion cells (RGCs) has been described. We show that differentiating chick RGCs that express the neurotrophic receptors p75 and TrkB while lacking retinoblastoma protein, a feature of tetraploid RGCs, also express p27K…