Multilevel Selection in Models of Prebiotic Evolution II: A Direct Comparison of Compartmentalization and Spatial Self-Organization

Multilevel selection has been indicated as an essential factor for the evolution of complexity in interacting RNA-like replicator systems. There are two types of multilevel selection mechanisms: implicit and explicit. For implicit multilevel selection, spatial self-organization of replicator populations has been suggested, which leads to higher level selection among emergent mesoscopic spatial patterns (traveling waves). For explicit multilevel selection, compartmentalization of replicators by vesicles has been suggested, which leads to higher level evolutionary dynamics among explicitly imposed mesoscopic entities (protocells). Historically, these mechanisms have been given separate consideration for the interests on its own. Here, we make a direct comparison between spatial self-organization and compartmentalization in simulated RNA-like replicator systems. Firstly, we show that both mechanisms achieve the macroscopic stability of a replicator system through the evolutionary dynamics on mesoscopic entities that counteract that of microscopic entities. Secondly, we show that a striking difference exists between the two mechanisms regarding their possible influence on the long-term evolutionary dynamics, which happens under an emergent trade-off situation arising from the multilevel selection. The difference is explained in terms of the difference in the stability between self-organized mesoscopic entities and externally imposed mesoscopic entities. Thirdly, we show that a sharp transition happens in the long-term evolutionary dynamics of the compartmentalized system as a function of replicator mutation rate. Fourthly, the results imply that spatial self-organization can allow the evolution of stable folding in parasitic replicators without any specific functionality in the folding itself. Finally, the results are discussed in relation to the experimental synthesis of chemical Darwinian systems and to the multilevel selection theory of evolutionary biology in general. To conclude, novel evolutionary directions can emerge through interactions between the evolutionary dynamics on multiple levels of organization. Different multilevel selection mechanisms can produce a difference in the long-term evolutionary trend of identical microscopic entities

Endophytic fungi from the roots of horseradish (Armoracia rusticana) and their interactions with the defensive metabolites of the glucosinolate myrosinase – isothiocyanate system

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In vitro and in vivo activity and cross resistance profiles of novel ruthenium (II) organometallic arene complexes in human ovarian cancer.

Ruthenium complexes offer the potential of reduced toxicity, a novel mechanism of action, non-cross resistance and a different spectrum of activity compared to platinum containing compounds. Thirteen novel ruthenium(II) organometallic arene complexes have been evaluated for activity (in vitro and in vivo) in models of human ovarian cancer, and cross-resistance profiles established in cisplatin and multi-drug-resistant variants. A broad range of IC50 values was obtained (0.5 to >100 microM) in A2780 parental cells with two compounds (RM175 and HC29) equipotent to carboplatin (6 microM), and the most active compound (HC11) equipotent to cisplatin (0.6 microM). Stable bi-dentate chelating ligands (ethylenediamine), a more hydrophobic arene ligand (tetrahydroanthracene) and a single ligand exchange centre (chloride) were associated with increased activity. None of the six active ruthenium(II) compounds were cross-resistant in the A2780cis cell line, demonstrated to be 10-fold resistant to cisplatin/carboplatin by a mechanism involving, at least in part, silencing of MLH1 protein expression via methylation. Varying degrees of cross-resistance were observed in the P-170 glycoprotein overexpressing multi-drug-resistant cell line 2780AD that could be reversed by co-treatment with verapamil. In vivo activity was established with RM175 in the A2780 xenograft together with non-cross-resistance in the A2780cis xenograft and a lack of activity in the 2780AD xenograft. High activity coupled to non cross-resistance in cisplatin resistant models merit further development of this novel group of anticancer compounds

Chemical composition of some traditional herbal drug preparations: essential oil and aromatic water of costmary (Balsamita suaveolens Pers.)

The compositions of the essential oil and the aromatic water of costmary (Balsamita suaveolens Pers.) cultivated in Tuscany were investigated. They represent the main ingredients of some traditional preparations sold commercially. The essential oil as such and the n-hexane extract of the aromatic water were analyzed by GC and GC-MS. Both samples were found to be rich in monoterpenes. Eighty-five compounds were identified, accounting for 95.1 and 95.4% of the essential oil and n-hexane extract of aromatic water, respectively. Carvone was the main compound (43.5% in the essential oil and 74.9% in the n-hexane extract of aromatic water). In addition, solid phase microextraction was used to sample the volatile organic compounds emitted from the fresh plant and from the aromatic water, and carvone was again the main component, amounting to 46.2 and 41.3%, respectively

Phylogeny of the genus Azospirillum based on 16S rDNA sequence

The 16S rDNA of 17 strains of Azospirillum, 14 assigned to one of the known species A. amazonense A. brasilense A. halopraeferens A. irakense and A. lipoferum, and the other three of uncertain taxonomic position, was sequenced after polymerase chain reaction amplification and analysed in order to investigate the phylogenetic relationships at the intra-generic and super-generic level. The phylogenetic analysis confirms that the genus Azospirillum constitutes a phylogenetically separate entity within the a subclass of Proteobacteria and that the five species are well defined. A. brasilense and A. lipoferum are closely related species and form one cluster together with A. halopraeferens; the pair of species A. amazonense and A. irakense forms a second cluster in which Rhodospirillum centenum is also placed

Phylogenetic studies of the genus Azospirillum

The 16S rDNA of seventeen Azospirillum strains, fourteen of which assigned to one of known A. amazonense, A. brasilense, A. halopraeferens, A. irakense and A. lipoferum species, and other three of uncertain taxonomic collocation, was sequenced and analysed after polymerase chain reaction amplification, in order to investigate the phylogenetic relationships at the intra-generic and super-generic level. Moreover the use of histidine biosynthetic genes and of anonymous sequences generated by RAPD technique to infer phylogenetic relationships among Azospirillum strains is also described. The relationships among the five species, as revealed by DNA sequence data, appeared to be congruent with other molecular and phenotypic results, showing that the genus Azospirillum constitutes a phylogenetically separate entity in which A. brasilense and A. lipoferum are very close species, whereas the species A. amazonense is the most divergent