Search results for "polyploidy"
showing 10 items of 40 documents
Genomic instability in an interspecific hybrid of the genus Saccharomyces: a matter of adaptability
2020
Ancient events of polyploidy have been linked to huge evolutionary leaps in the tree of life, while increasing evidence shows that newly established polyploids have adaptive advantages in certain stress conditions compared to their relatives with a lower ploidy. The genus Saccharomyces is a good model for studying such events, as it contains an ancient whole-genome duplication event and many sequenced Saccharomyces cerevisiae are, evolutionary speaking, newly formed polyploids. Many polyploids have unstable genomes and go through large genome erosions; however, it is still unknown what mechanisms govern this reduction. Here, we sequenced and studied the natural S. cerevisiae × Saccharomyces…
Topoisomerase II inhibition and high yield of endoreduplication induced by the flavonoids luteolin and quercetin
2006
Luteolin and quercetin are widely distributed plant flavonoids that possess a variety of chemical and biological activities, including free-radical scavenging and antioxidant activity. Recently, both flavonoids have been reported to inhibit DNA topoisomerases I and II (topo I and topo II), a property that, together with their ability to induce DNA and chromosome damage, has made them candidate anticancer compounds. In the present study, we confirmed that both compounds are topo II inhibitors by conducting a comparative study of their effect on topo II activity from Chinese hamster ovary AA8 cells. Because interference with the function of topo II to resolve DNA entanglement at the end of re…
Taxonomic complexity in the halophyte Limonium vulgare and related taxa (Plumbaginaceae): insights from analysis of morphological, reproductive and k…
2014
Part of a special issue on halophytes and saline adaptations Background and Aims Limonium is awell-known example of a group of plants that is taxonomically complex due to certain biological characteristics that hamper species’ delineation. The closely related polyploid species Limonium vulgare Mill., L. humile Mill. and L. narbonense Mill. are defined species and can be used for studying patterns of morphological and reproductive variation. The first two taxa are usually found in Atlantic Europe and the third in the Mediterranean region, but a numberof intermediate morphological formsmay be present alongside typical examples of these species. This study attempts to elucidate morphological, …
Incomplete sequence homogenization in 45S rDNA multigene families: intermixed IGS heterogeneity within the single NOR locus of the polyploid species …
2014
† Background and Aims Ribosomal sequences have become the classical example of the genomic homogenization of nuclear multigene families. Despite theoretical advantages and modelling predictions that support concerted evolution of the 45S rDNA, several reports have found intragenomic polymorphisms. However, the origins and causes of these rDNA polymorphisms are difficult to assess because seed plants show a wide range of 45S rDNA loci number variation, especially in polyploids. Medicago arborea is a tetraploid species that has a single 45S rDNA locus. This feature makes this species a suitable case study to assess the fate of ribosomal IGS homogenization in polyploid species showing nucleolu…
Factors influencing survival after resection of pancreatic cancer. A DNA analysis and a histomorphologic study
1994
BACKGROUND The influence of DNA content on prognosis in stomach cancer has been investigated rarely, and the results are controversial. METHOD The prognostic relevance of the DNA content and histomorphologic parameters was evaluated in 41 patients after resection of pancreatic cancer. RESULTS In the univariate analysis, the DNA content, tumor size, lymph node status, tumor stage, nuclear grade, and type of resection had a statistically significant influence on the prognosis. No association was found between the DNA content and the histomorphologic features. Apart from the operative procedure, the DNA content was the strongest indicator of prognosis in the multivariate analysis. CONCLUSIONS …
Origin and ploidy of multipronuclear zygotes
2000
Recently, several authors have proposed strategies for correction of triploidy based on the removal of the extra pronucleus at the zygote stage. In the present bioassay, the following were analysed: (1) the different factors that can induce the formation of multipronuclear zygotes in mammals; (2) the different morphological patterns established according to the number of pronuclei and polar bodies that can be observed at the zygote stage and used to distinguish the origin of multipronuclear zygotes; and (3) the pattern of chromosomal segregation during the first mitotic division and ploidy status of the resulting preim-plantation embryos. Such an analysis shows that the morphological crite…
Chromosomal rearrangements in childhood acute myeloid leukemia and myelodysplastic syndromes.
1999
Recurrent chromosomal abnormalities present in the malignant cells of children with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) often correlate closely with specific clinical and biologic characteristics of the disease. Certain unique cytogenetic rearrangements are associated with distinct morphologic leukemic subtypes. These rearrangements should be detectable in most children with AML and MDS with the use of complementary molecular techniques such as fluorescence in situ hybridization (FISH), Southern blotting, and polymerase chain reaction. Apart from the diagnostic assessment, cytogenetic findings sometimes predict clinical outcome and thus also serve as prognostic …
Relationships of the Woody Medicago Species (Section Dendrotelis) Assessed by Molecular Cytogenetic Analyses
2008
†Background and Aims The organization of rDNA genes in the woody medic species from the agronomically important Medicago section Dendrotelis was analysed to gain insight into their taxonomic relationships, to assess the levels of infraspecific variation concerning ribosomal loci in a restricted and fragmented insular species (M. citrina) and to assess the nature of its polyploidy. †Methods Fluorescence in situ hybridization (FISH) was used for physical mapping of 5S and 45S ribosomal DNA genes in the three species of section Dendrotelis (M. arborea, M. citrina, M. strasseri) and the related M. marina from section Medicago. Genomic in situ hybridization (GISH) was used to assess the genomic …
Activation of self-renewal and meiotic genes in tumour cell lines resistant to genotoxic treatment
2014
Pašatjaunošanās un meijotisko gēnu aktivācija pēc genotoksiskas apstrādes rezistentās audzēju šūnu līnijās Šajā darbā tika pētīta iespējamā saistība starp poliploīdijas un dzimumšūnu līnijai raksturīgo gēnu indukciju pēc pretvēža apstrādes atkarībā no TP53 statusa un audzēju šūnu rezistence pret DNS bojājumu. Pirmo reizi tika atrasta un citoloģiski raksturota galveno cilmestības transkripcijas faktoru OCT4, NANOG un SOX2 ekspresijas aktivācija, kas izraisīta pārkāpjot tetraploīdo barjeru pēc DNS bojājuma TP53 mutantās, bet ne funkcionālās audzēja šūnas, kā arī galvenā mejotiskā kohezīna REC8 ekspresija somatisko audzēja šūnu līnijās, kas apstrādātas ar jonizējošo starojumu vai topoizomeraze…
ENDOPOLYPLOIDY OF ENDANGERED PLANT SPECIES LIGULARIA SIBIRICA IN DIFFERENT ENVIRONMENTS
2017
The goal of this study was to detect endopolyploidy of Ligularia sibirica from populations existed in different ecological conditions. This is important step to elaborate the appropriate protection measures of rare and endangered species, which should be based on understanding of ongoing processes in populations. From this point of view the knowledge of genetic diversity, including endopolyploidy level between and within populations, is crucial. L. sibirica is endangered and protected plant species in Latvia which is included in the protected plants list of EU Habitat directive 92/43/EEK Annexes 2 and 4. Perennial herbaceous plant L. sibirica is one of two species of genus Ligularia in Euro…