Astonishing 35S rDNA diversity in the gymnosperm species Cycas revoluta Thunb

17 p., tablas, gráficos.In all eukaryotes, the highly repeated 35S ribosomal DNA (rDNA) sequences encoding 18S-5.8S-26S ribosomal RNA (rRNA) typically show high levels of intragenomic uniformity due to homogenisation processes, leading to concerted evolution of 35S rDNA repeats. Here, we compared 35S rDNA divergence in several seed plants using next generation sequencing and a range of molecular and cytogenetic approaches. Most species showed similar 35S rDNA homogeneity indicating concerted evolution. However, Cycas revoluta exhibits an extraordinary diversity of rDNA repeats (nucleotide sequence divergence of different copies averaging 12 %), influencing both the coding and non-coding rDNA regions nearly equally. In contrast, its rRNA transcriptome was highly homogeneous suggesting that only a minority of genes ( T substitutions located in symmetrical CG and CHG contexts which were also highly methylated. Both functional genes and pseudogenes appear to cluster on chromosomes. The extraordinary high levels of 35S rDNA diversity in C. revoluta, and probably other species of cycads, indicate that the frequency of repeat homogenisation has been much lower in this lineage, compared with all other land plant lineages studied. This has led to the accumulation of methylation-driven mutations and pseudogenisation. Potentially, the reduced homology between paralogs prevented their elimination by homologous recombination, resulting in long-term retention of rDNA pseudogenes in the genome.The work was supported by the Czech Science Foundation (P501/13/10057S and P501/12/G090) and NERC (UK).Peer reviewe

Genetic and epigenetic features of gymnosperm genomes

Trabajo presentado en el 23rd Symposium on Biodiversity and Evolutionary Biology of the German Botanical Societ, celebrado en Munich (Alemania), del 8 al 11 de septiembre 2016Peer reviewe

Supplementary Material for: High Penetrance of a Pan-<b><i>Canina</i></b> Type rDNA Family in Intersection <b><i>Rosa</i></b> Hybrids Suggests Strong Selection of Bivalent Chromosomes in the Section <b><i>Caninae</i></b>

All dogroses <i>(Rosa</i> sect. <i>Caninae)</i> are characterized by the peculiar <i>canina</i> meiosis in which genetic material is unevenly distributed between female and male gametes. The pan-<i>canina</i> rDNA family (termed beta) appears to be conserved in all dogroses analyzed so far. Here, we have studied rDNAs in experimental hybrids obtained from open pollination of F1 plants derived from 2 independent intersectional crosses between the pentaploid dogrose species (2n = 5x = 35) <i>Rosa rubiginosa</i> as female parent (producing 4x egg cells due to the unique asymmetrical <i>canina</i> meiosis) and the tetraploid (2n = 4x = 28) garden rose <i>R. hybrida</i> ‘André Brichet' as male parent (producing 2x pollen after normal meiosis). We analyzed the structure of rDNA units by molecular methods [CAPS and extensive sequencing of internal transcribed spacers (ITS)] and determined the number of loci on chromosomes by FISH. FISH showed that <i>R. rubiginosa</i> and ‘André Brichet' harbored 5 and 4 highly heteromorphic rDNA loci, respectively. In the second generation of hybrid lines, we observed a reduced number of loci (4 and 5 instead of the expected 6). In <i>R. rubiginosa</i> and ‘André Brichet', 2-3 major ITS types were found which is consistent with a weak homogenization pressure maintaining high diversity of ITS types in this genus. In contrast to expectation (the null hypothesis of Mendelian inheritance of ITS families), we observed reduced ITS diversity in some individuals of the second generation which might derive from self-fertilization or from a backcross to <i>R. rubiginosa</i>. In these individuals, the pan-<i>canina</i> beta family appeared to be markedly enriched, while the paternal families were lost or diminished in copies. Although the mechanism of biased meiotic transmission of certain rDNA types is currently unknown, we speculate that the bivalent-forming chromosomes carrying the beta rDNA family exhibit extraordinary pairing efficiency and/or are subjected to strong selection in <i>Caninae</i> polyploids

A Contribution to the Glimepiride Dissociation Constant Determination

Knowledge of druglike properties, such as dissociation constants (pK(a)), is of great importance in drug development and analysis. However, poor aqueous Solubility often Causes serious limitations ill accurate determination of a drug's pK(a). In this Study, the apparent dissociation constant (pK(a)') of the poorly soluble drug, glimepiride, has been determined by application of the spectrophotometric and Solubility methods. Compared to the literature reported glimepiride pK(a)' values of 4.99 +/- 0.50 and 6.2 +/- 0.1, the values obtained in the present study were 8.07 +/- 0.02 and 7.26 +/- 0.01 determined by the spectrophotometric and Solubility method, respectively. In addition, the advantages of these two methods in pK(a)' determination of glimepiride are discussed

Hvordan kan minner skape relasjoner mellom fortid, nåtid og fremtid hos barn/unge som har mottatt oppfølging fra barnevernet?

I denne masteroppgaven i familieterapi og systemisk praksis, har jeg ønsket å finne svar på følgende problemstilling: Hvordan kan minner skape relasjoner mellom fortid, nåtid og fremtid hos barn/unge som har mottatt oppfølging fra barnevernet? Dette er en kvalitativt studie, hvor data er samlet inn gjennom bruk av metoden memory-work (minnearbeid). Gjennom et kollektivt intervju snakket jeg med tre informanter over 18 år, som har mottatt oppfølging fra barnevernet. Før dette intervjuet, ble informantene bedt om å oversende et skriftlig minne med følgende trigger: «En julefeiring fra barndommen jeg aldri vil glemme». Dette minnet dannet utgangspunkt for det kollektive intervjuet. Datamaterialet er transkribert og utgjør materialet i analyse