Phylogeny of the American silverfish Cubacubaninae (Hexapoda: Zygentoma: Nicoletiidae): a combined approach using morphology and five molecular loci

Relationships within the subfamily Cubacubaninae, the dominant subfamily of Nicoletiidae in America, are appraised based on parsimony analysis of 20 morphological characters and sequence data from five loci (nuclear 18S and 28S rRNA, mitochondrial 16S rRNA, nuclear protein coding gene histone H3, and mitochondrial protein coding gene cytochrome c oxidase subunit I). The data, analyzed under direct optimization for a range of analytical parameter sets, indicated that species may show some biogeographical structure. It also indicated that the presence of articulated submedian appendages on urosternum IV is not a valid discriminating character in taxonomy. Species within the traditional genera Anelpistina, Cubacubana and Neonicoletia were found to belong to a group in which no clear morphological or molecular distinction was present. It is proposed that members of these three genera should be united within a single taxon. On the contrary, the genus Prosthecina is well supported by the data. © The Willi Hennig Society 2006.     

Tracing horizontal Wolbachia movements among bees (Anthophila): a combined approach using multilocus sequence typing data and host phylogeny

The endosymbiotic bacterium Wolbachia enhances its spread via vertical transmission by generating reproductive effects in its hosts, most notably cytoplasmic incompatibility (CI). Additionally, frequent interspecific horizontal transfer is evident from a lack of phylogenetic congruence between Wolbachia and its hosts. The mechanisms of this lateral transfer are largely unclear. To identify potential pathways of Wolbachia movements, we performed multilocus sequence typing of Wolbachia strains from bees (Anthophila). Using a host phylogeny and ecological data, we tested various models of horizontal endosymbiont transmission. In general, Wolbachia strains seem to be randomly distributed among bee hosts. Kleptoparasite‐host associations among bees as well as other ecological links could not be supported as sole basis for the spread of Wolbachia. However, cophylogenetic analyses and divergence time estimations suggest that Wolbachia may persist within a host lineage over considerable timescales and that strictly vertical transmission and subsequent random loss of infections across lineages may have had a greater impact on Wolbachia strain distribution than previously estimated. Although general conclusions about Wolbachia movements among arthropod hosts cannot be made, we present a framework by which precise assumptions about shared evolutionary histories of Wolbachia and a host taxon can be modelled and tested.     

Prototropic tautomerism of imidazolone in aqueous solution: a density functional approach using the combined discrete/self-consistent reaction field (SCRF) models

A systematic investigation of the proton transfer in the keto-amino/enol tautomerization of imidazolone was undertaken. Calculations in aqueous solution were performed using both combined discrete/self-consistent reaction field (SCRF) and SCRF methods. Complexes containing one to three water molecules around the hydrophilic site of imidazolone were used for the combined discrete/SCRF calculations. The DFT results predict that the barrier height for non-water-assisted intramolecular proton transfer is very high (214.8 kJmol^–1). Hydrogen bonding between imidazolone and the water molecule(s) will dramatically lower the barrier by a concerted multiple proton transfer mechanism. The proton transfer process through a eight-member ring formed by imidazolone and two water molecules is found to be more efficient and the calculated barrier height is ca. 61 kJmol^–1.Figure DFT calculations in aqueous solution predict the H-bonding between imidazolone(IZ) and the water molecule(s) will dramatically lower the tautomeric barrier by a concerted multiple proton transfer mechanism, in which an eight-member ring structure formed by IZ and 2H₂O is found to be more efficient and the barrier is 60.8 kJ mol^–1, much less than 214.8 kJ mol^–1 in the non-water-assisted mechanism.