Genome size evolution of the extant lycophytes and ferns

Ferns and lycophytes have remarkably large genomes. However, little is known about how their genome size evolved in fern lineages. To explore the origins and evolution of chromosome numbers and genome size in ferns, we used flow cytometry to measure the genomes of 240 species (255 samples) of extant ferns and lycophytes comprising 27 families and 72 genera, of which 228 species (242 samples) represent new reports. We analyzed correlations among genome size, spore size, chromosomal features, phylogeny, and habitat type preference within a phylogenetic framework. We also applied ANOVA and multinomial logistic regression analysis to preference of habitat type and genome size. Using the phylogeny, we conducted ancestral character reconstruction for habitat types and tested whether genome size changes simultaneously with shifts in habitat preference. We found that 2C values had weak phylogenetic signal, whereas the base number of chromosomes (x) had a strong phylogenetic signal. Furthermore, our analyses revealed a positive correlation between genome size and chromosome traits, indicating that the base number of chromosomes (x), chromosome size, and polyploidization may be primary contributors to genome expansion in ferns and lycophytes. Genome sizes in different habitat types varied significantly and were significantly correlated with habitat types; specifically, multinomial logistic regression indicated that species with larger 2C values were more likely to be epiphytes. Terrestrial habitat is inferred to be ancestral for both extant ferns and lycophytes, whereas transitions to other habitat types occurred as the major clades emerged. Shifts in habitat types appear be followed by periods of genomic stability. Based on these results, we inferred that habitat type changes and multiple whole-genome duplications have contributed to the formation of large genomes of ferns and their allies during their evolutionary history.     

尊重斯德哥尔摩的历史中心—骑士岛的激活改造

瑞典国家财产委员会拥有骑士岛的所有权与管理权，并计划对该岛上所有的公共空间进行更新和开发，以提高其可达性与吸引力。该项目的核心是找到一种更新和修复岛屿的方法，从而在尊重历史价值的同时满足现代功能需求。对骑士岛南部的改造是岛上公共空间更新的第一部分。设计的关键条件是沿滨水区域创造可以供人步行与停坐的大面积空间，并在保持开放海港氛围的同时，对旧的道路铺装进行管理。设计者设计了一套灵活使用公共空间的综合解决方案，将开放空间与之前的码头一样，沿着水滨的形态进行布局。     

Microbial hydroxylation of non-activated carbon atoms in racemic 2-dodeceno-1-yl-succinic anhydride by <Emphasis Type="Italic">Mortierella isabellina 212</Emphasis>

Microbial hydroxylation of 2-dodecen-1-yl-succinic anhydride at non-activated carbon atoms has been described. A screening with fourteen fungi strains was carried out. Most of the microorganisms transformed the substrate into new products. Biotransformation conditions with Mortierella isabellina 212 were optimized. Optically active products of hydroxylation at C–10 and C–11 were isolated. Chemical structures of the unreacted optically active substrate and the products were determined by spectroscopic methods (¹H NMR, ¹³C NMR, GCMS, IR). Non-enzymatic hydrolysis of the anhydride at different pH was studied and methods of detection of the anhydride and the forming acid were discussed.     

The effect of growth regulators on sodium azide induced genetic damage in barley

The influence of growth regulators (GA and IAA) on the genetic effects of sodium azide was studied. Treatments with growth regulators were administered either prior to or after the mutagen. Post-treatments were found to be more effective against mutagen-induced plant growth injury and gave a slightly higher frequency of mutations. M₁ spike sterility however showed a rise following treatments with growth regulators.     

Does 29-mer RNA hairpin of the HIV-1 TAR RNA sequence bind magnesium? 19F-NMR and modelling studies.

5-Fluorouridine residues have been introduced into functionally important bulge and loop regions of 29-mer HIV-1 TAR RNA hairpins I and II to study Mg2+ and Ca2+ binding using 19F-NMR spectroscopy. There was no substantial binding detected up to 20-molar excess in case of both cations, whereas association of argininamide, used as a reference ligand, could be detected at less than 1-molar excess. The deltadelta 19F value of 1.93 ppm observed for (F)U23 upon argininamide binding is in agreement with former NMR studies of TAR RNA/argininamide complex. However, obtained results do not confirm U38 x A27 x U23 base-triple formation. The unmodified HIV-1 TAR RNA hairpin resulted from 600 ps in aqua molecular dynamics simulation was subjected to a molecular mechanics modelling of Mg+ binding.