1,721,042 research outputs found
Different fates of metabolites and small variation in chemical composition characterise frass chemistry in a specialist caterpillar
No full textAbstract
Specialist and generalist insect herbivores evolved different strategies to process host‐plant metabolites. We explored frass composition in
Laothoe populi
(L.) caterpillars (Lepidoptera: Sphingidae), a specialist moth species that is closely associated with plants of the Salicaceae (Mirb.) family. We fed the caterpillars with leaves from three willow species (
Salix caprea
L.,
S. purpurea
L. and
S. viminalis
L.), one willow hybrid (
S.
x
rubens
Schrank) and one poplar species (
Populus tremula
L.). Using untargeted metabolomics, we compared the chemical composition and variation among leaf and frass samples. We quantified the chemical variation using either a simple index based on the presence and concentration of metabolites (i.e., Bray‐Curtis) or an index that additionally accounts for chemical structural‐compositional similarity (CSCS) among metabolites. Due to the high degree of dietary specialisation, we expected low host‐specific variation in frass composition among the caterpillars. Based on literature, we further hypothesised that ingested salicinoids will be largely modified in the caterpillar gut while flavonoids will be often passively excreted. Finally, we compared chemical variation among the samples when quantified with Bray‐Curtis or CSCS metrics. As expected, we found relatively low host‐specific variation in the chemical composition of caterpillar frass. Our results further suggest that flavonoids were largely passively excreted by the caterpillars, while salicinoids were metabolised in the gut. Finally, we found that chemical composition measures based on Bray‐Curtis overestimated the differences in chemical composition between frass and leaves, suggesting that for these type of samples CSCS measures are better suited to reflect metabolic changes more realistically.Grantová Agentura České Republiky https://doi.org/10.13039/50110000182
Highly Diverse Shrub Willows (Salix L.) Share Highly Similar Plastomes
Full text linkPlastome phylogenomics is used in a broad range of studies where single markers do not bear enough information. Phylogenetic reconstruction in the genus Salix is difficult due to the lack of informative characters and reticulate evolution. Here, we use a genome skimming approach to reconstruct 41 complete plastomes of 32 Eurasian and North American Salix species representing different lineages, different ploidy levels, and separate geographic regions. We combined our plastomes with published data from Genbank to build a comprehensive phylogeny of 61 samples (50 species) using RAxML (Randomized Axelerated Maximum Likelihood). Additionally, haplotype networks for two observed subclades were calculated, and 72 genes were tested to be under selection. The results revealed a highly conserved structure of the observed plastomes. Within the genus, we observed a variation of 1.68%, most of which separated subg. Salix from the subgeneric Chamaetia/Vetrix clade. Our data generally confirm previous plastid phylogenies, however, within Chamaetia/Vetrix phylogenetic results represented neither taxonomical classifications nor geographical regions. Non-coding DNA regions were responsible for most of the observed variation within subclades and 5.6% of the analyzed genes showed signals of diversifying selection. A comparison of nuclear restriction site associated DNA (RAD) sequencing and plastome data on a subset of 10 species showed discrepancies in topology and resolution. We assume that a combination of (i) a very low mutation rate due to efficient mechanisms preventing mutagenesis, (ii) reticulate evolution, including ancient and ongoing hybridization, and (iii) homoplasy has shaped plastome evolution in willows
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
SBToolCZ new version: An analysis of a few updated environmental parameters on a case study
No full textIn the past decade, the world has faced many challenges, including the effects resulting from human-induced greenhouse gas emissions. In the construction industry, efforts are being made to combat climate change and protect the environment by developing rating systems aimed at designing sustainable buildings. One of these tools is SBToolCZ, the Czech national certification used to assess the sustainability of various building typologies. Still, as buildings are becoming more energy-efficient, which should ensure low carbon emissions, the environmental impacts of building components should be methodically examined. This paper compares two versions of the tool specifically addressed to office buildings – the one developed in 2011 and the recently updated version developed in accordance with the new priorities indicated by the European Green Deal. The comparative analysis investigates what has been changed, focusing on six environmental impacts calculated for the A1-A3, B4 and B6 LCA stages applied to an office building. On this basis, the paper aims to assess two different SBToolCZ versions and understand how the Methodology has been modified considering a case study and six environmental parameters
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
