1,720,997 research outputs found
Die soziale Dimension des Klimaschutzes und der Energieeffizienz im Kontext von Bau- und Wohnungswirtschaft
Full text linkDIE SOZIALE DIMENSION DES KLIMASCHUTZES UND DER ENERGIEEFFIZIENZ IM KONTEXT VON BAU- UND WOHNUNGSWIRTSCHAFT
Die soziale Dimension des Klimaschutzes und der Energieeffizienz im Kontext von Bau- und Wohnungswirtschaft / Gerth, Michael [Bearb.] (Rights reserved) (-
A multilocus sequence typing (MLST) approach to diminish the problems that are associated with DNA barcoding: A reply to Stahlhutet al. (2012)
No full textComparative genomics provides a timeframe for Wolbachia evolution and exposes a recent biotin synthesis operon transfer
No full textThe genus Wolbachia (Alphaproteobacteria) comprises the most abundant inherited intracellular bacteria1. Despite their relevance as manipulators of human pathogen transmission2 and arthropod reproduction3, many aspects of their evolutionary history are not well understood4. In arthropods, Wolbachia infections are typically transient on evolutionary timescales5,6 and co-divergence between hosts and Wolbachia is supposedly rare. Consequently, much of our knowledge of Wolbachia genome evolution derives from very recently diverged strains, and a timescale for Wolbachia is lacking. Here, we investigated the genomes of four Wolbachia strains that have persisted within and co-diverged with their host lineage for ∼2 million years. Although the genomes showed very little evolutionary change on a nucleotide level, we found evidence for a recent lateral transfer of a complete biotin synthesis operon that has the potential to transform Wolbachia-host relationships7. Furthermore, this evolutionary snapshot enabled us to calibrate the divergence times of the supergroup A and B Wolbachia lineages using genome-wide data sets and relaxed molecular clock models. We estimated the origin of Wolbachia supergroups A and B to be ∼200 million years ago (Ma), which is considerably older than previously appreciated. This age coincides with the diversification of many insect lineages8 that represent most of Wolbachia's host spectrum
A critical re-evaluation of multilocus sequence typing (MLST) efforts in<i>Wolbachia</i>
No full textAbstractWolbachia(Alphaproteobacteria, Rickettsiales) is the most common, and arguably one of the most important inherited symbionts. Molecular differentiation ofWolbachiastrains is routinely performed with a set of five multilocus sequence typing (MLST) markers. However, since its inception in 2006, the performance of MLST inWolbachiastrain typing has not been assessed objectively. Here, we evaluate the properties ofWolbachiaMLST markers and compare it to 252 other single copy loci present in the genome of mostWolbachiastrains. Specifically, we investigated how well MLST performs at strain differentiation, at reflecting genetic diversity of strains, and as phylogenetic marker. We find that MLST loci are outperformed by other loci at all tasks they are currently employed for, and thus that they do not reflect the properties of aWolbachiastrain very well. We argue that whole genome typing approaches should be used forWolbachiatyping in the future. Alternatively, if few-loci-approaches are necessary, we provide a characterization of 252 single copy loci for a number a criteria, which may assist in designing specific typing systems or phylogenetic studies.</jats:p
Extensive screen for bacterial endosymbionts reveals taxon-specific distribution patterns among bees (Hymenoptera, Anthophila)
No full textBacterial endosymbionts play key roles in arthropod biology, ranging from beneficial mutualists to parasitic sex ratio manipulators. The number of described endosymbiotic bacterial taxa has accumulated continuously in recent years. While the understanding of arthropod-microbe interactions has advanced significantly, especially in model organisms, relatively little is known about symbiont distribution and effects in non-model organisms. As a first step to alleviate this gap in understanding, we performed an endosymbiont survey in bees (Anthophila), an ecologically and economically important group of hymenopterans. To this end, we sampled 170 bee species and screened by PCR for the presence of Wolbachia, Rickettsia, Arsenophonus and Cardinium. Detected strains were then further diagnosed by additional markers. Additionally, we tested if certain ecological traits, bee phylogeny or geographic origin of bees explain endosymbiont distribution. Our results indicate that supergroup A Wolbachia are very common in bees and that their distribution can be significantly correlated to both host ecology and phylogeny, although a distinction of these factors is not possible. Furthermore, bees from the same region (Old World or New World) are more likely to harbour identical Wolbachia strains than expected by chance. Other endosymbionts (Rickettsia, Arsenophonus) were less common, and specific to particular host taxa, suggesting that host phylogeny is a major predictor for endosymbiont distribution in bees
Data from: Tracing horizontal Wolbachia movements among bees (Anthophila): a combined approach using multilocus sequence typing data and host phylogeny
No full textThe 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
<i>Wolbachia</i>infections in bees (Anthophila) and possible implications for DNA barcoding
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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